Textile products having selectively applied sealant or coating with visual indicator and method of detecting the same
11577003 · 2023-02-14
Assignee
Inventors
- David Granville Stevenson (Strathclyde, GB)
- Timothy Rawden Ashton (Strathclyde, GB)
- Lindsey Calcutt (Pinebluff, NC, US)
- Paul Van Hulle (Pinebluff, NC, US)
- James Wade Curlee (Pinebluff, NC, US)
Cpc classification
C08L39/06
CHEMISTRY; METALLURGY
C08L39/06
CHEMISTRY; METALLURGY
International classification
A61L27/50
HUMAN NECESSITIES
A61L31/14
HUMAN NECESSITIES
A61L31/12
HUMAN NECESSITIES
Abstract
A method of detecting the presence or absence of a sealant applied to a textile graft includes the steps of: providing a textile graft having a first surface and an opposed second surface; providing a water soluble masking agent; applying the water soluble masking agent to at least a portion of the first surface of the textile graft; providing a sealant solution; providing a visual indicator; applying the water insoluble sealing agent and the visual indicator to the second surface of the textile graft; and removing the water soluble masking agent after the step of applying sealing solution. The second surface has visual indication of the visual indicator and the first surface is substantially free of visual indication of the visual indicator. An implantable textile graft includes the selectively applied visual indicator.
Claims
1. An implantable textile graft comprising: a first surface having a textile pattern of inter-engaging yarns and interstices between or in the yarns, wherein a portion of the first surface comprises a removable coating, which comprises at least one substantially water-soluble material, disposed thereon, which removable coating is substantially removed prior to implantation; a second surface opposed to, and spaced apart from, the first surface, wherein at least a portion of the second surface comprises a visually discernable colored sealant coating disposed thereon, the visually discernable colored sealant coating comprising (a) a water insoluble sealing agent selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof, and (b) a visually discernable colorant; wherein the removable coating substantially prevents migrating of the visually discernable colored sealant coating onto the first surface; and wherein the visually discernable colored sealant coating is configured to be visually distinguishable by the colorant and identifiable by the vision of a practitioner during a surgical procedure comprising the implantable textile graft, and based solely on the presence or absence of the visually discernable colorant to enable the practitioner to determine whether the implantable graft does comprise the water insoluble sealing agent.
2. The graft of claim 1, wherein the first surface is at least 70% free of the visually discernable colorant.
3. The graft of claim 1, wherein the water insoluble sealing agent is disposed over the interstices between and in the yarns.
4. The graft of claim 1, wherein the textile graft is substantially impermeable to liquid.
5. The graft of claim 1, wherein the textile graft has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
6. The graft of claim 1, wherein the visually discernable colorant is biocompatible.
7. The graft of claim 1, wherein the visually discernable colorant has a non-white color.
8. The graft of claim 7, wherein the non-white color is selected from the group consisting of blue, green, red, orange, and combinations thereof.
9. The graft of claim 1 wherein the textile pattern of inter-engaging yarns defines a tubular textile wall, wherein the first surface is an inner surface of the tubular textile wall, and wherein the second surface is an outer surface of the tubular textile wall.
10. The graft of claim 9, further comprising a support member disposed about the tubular textile wall.
11. The graft of claim 10, wherein the support member is disposed about the outer surface of the tubular textile wall.
12. The graft of claim 11, wherein the support member is wrapped around the outer surface of the tubular textile wall.
13. The graft of claim 12, wherein the tubular textile wall comprises a plurality of crimps, and the support member is arranged to nest among the plurality of crimps.
14. The graft of claim 10, wherein the support member is a flexible, polymer member.
15. The graft of claim 10, wherein the support member is a metallic member.
16. The graft of claim 1, wherein the sealant coating comprises a solution of a solvent, the water insoluble sealing agent and the visually discernable colorant.
17. The graft of claim 16, wherein the textile pattern of inter-engaging yarns defines a tubular textile wall, wherein the first surface is an inner surface of the tubular textile wall, and wherein the second surface is an outer surface of the tubular textile wall; and wherein, when viewed in a cross-section of the tubular textile wall, at least a portion of the tubular textile wall proximal to the second surface has the visual indication of the visually discernable colorant and at least a portion of the tubular textile wall proximal to the first surface is substantially free of the visually discernable colorant.
18. The graft of claim 1, wherein, after the removable coating is removed, the first surface is observable, whereby observation of the first surface is substantially free of visual indication of the visually discernable colorant.
19. The implantable textile graft of claim 1, wherein the visually discernable colored sealant coating is configured to be non-white and readily visually distinguishable from blood and tissue by the vision of a practitioner during a surgical procedure comprising the implantable textile graft.
20. The implantable textile graft of claim 1, wherein the visually discernable colored sealant coating is configured to inform the practitioner of the presence of the colored sealant coating.
21. The graft of claim 11, wherein the support member is encapsulated or embedded in the visually discernable colored sealant coating.
22. A method for determining whether an implantable graft comprises a water insoluble sealing agent using the unaided vision of a medical practitioner comprising: providing the implantable graft of claim 1 to a medical practitioner for implantation in a patient; visually inspecting the second surface of the implantable graft, and determining that the second surface at least a portion of the implantable graft comprises the visually discernable colorant of the visually discernable colored sealant coating; and thereby concluding that the implantable graft does comprise the water insoluble sealing agent.
23. An implantable textile graft comprising an initial removable coating on a first surface which is removed prior to implanting the implantable textile graft, the implantable textile graft comprising after removal of the removable coating: a first surface comprising a textile of inter-engaging yarns; a second surface that is opposed to, and spaced apart from, the first surface, the second surface comprising a visually discernable colored sealant coating comprising a water insoluble sealing agent selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof, and a visually discernable colorant, wherein the visually discernable colored sealant coating at least partially covers the textile, wherein the first surface is substantially free of the visually discernable colorant, and wherein the colored sealant coating is configured to enable a practitioner to visually determine, based solely on the presence of the visually discernable colorant of the visually discernable colored sealing coating, that the implantable textile graft comprises the water insoluble sealing agent.
24. The implantable textile graft of claim 23, wherein the colored sealant coating is configured to visually determine that the implantable graft comprises the water insoluble sealing agent by the practitioner's vision before or during a surgical procedure.
25. The implantable textile graft of claim 23, wherein the colored sealant coating comprises a colorant having a color that differs from blood and/or tissue.
26. The implantable textile graft of claim 23, wherein the first surface comprises at least 70% free of the visually discernable colorant.
27. The graft of claim 23, wherein the textile graft is substantially impermeable to liquid.
28. The graft of claim 23, wherein the textile graft has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
29. A method for determining whether an implantable graft comprises a water insoluble sealing agent using the unaided vision of a medical practitioner comprising: providing the implantable graft of claim 23 to a medical practitioner for implantation in a patient; visually inspecting the second surface of the implantable graft, and determining that the second surface at least a portion of the implantable graft comprises the visually discernable colorant of the visually discernable colored sealant coating; and thereby concluding that the implantable graft does comprise the water insoluble sealing agent.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Embodiments of the invention will now be described, by way of example, with reference to the drawings, in which:
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DETAILED DESCRIPTION OF THE INVENTION
(30) As used herein the term “substantially” and its equivalents refer to being at least 70% of a stated value, desirably within at least 80% of a stated value, and more desirably within 90% or 95% of a stated value.
(31) As used herein the terms “about” or “approximate” and their equivalents refer to being within (plus and/or minus) at least 20% of a stated value, desirably within at least 10% of a stated value, and more desirably within 5% of a stated value.
(32) As used herein the terms “layer” and “coating” may be used interchangeably to refer to a deposition of material over, underneath, or within a substrate, such as a textile substrate.
(33) As used herein masking agent shall refer to any suitable non-biological, e.g., synthetic, hydrophilic polymer and any suitable biological hydrophilic polymer. However, it should be understood that other masking agents may be used.
(34) With reference to
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(36) The conduit 10 comprises polyethylene terephthalate (PET). However, it should be understood that the conduit 10 could comprise other materials, such as polytetrafluoroethylene (PTFE). Other suitable polymers for medical textile applications may include, but are not limited to polyolefin, polyester, poly(ether amide), poly(ether ester), poly(ether urethane), poly(ester urethane), poly(ethylene-styrene/butylene-styrene), and other block copolymers.
(37) In the embodiment illustrated and described here, the weft yarn pick-rate of the conduit 10 is approximately 45 ppcm. However, it should be understood that the weft yarn pick-rate of the conduit 10 could be between approximately 25 ppcm and approximately 50 ppcm.
(38) The conduit 10 is moveable between a contracted state and an extended state.
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(40) The conduit 10 depicted in
(41) In the embodiment illustrated here, the conduit 10 has a substantially uniform cross section throughout. However, it should be understood that the conduit 10 could have an irregular cross section throughout. For example, if the conduit 10 is to be connected between a further prosthesis, such as a heart valve, and an end of a severed blood vessel, the conduit 10 could have an irregular cross section throughout. As described in more detail below, in some embodiments the conduit 10 could be configured to have differing degrees of flexibility, either by selectively adding sealant 14 to different sections of the conduit 10, or in other ways.
(42) As described above, it is desirable for the inner surface 10a of the wall 10f of the conduit 10 to remain free from, or substantially devoid of, the material used to seal the conduit 10. The reason for this is to ensure that the inner surface 10a of the wall 10f of the conduit 10, remains of a porous 10e, woven nature, to ensure that when the vascular prosthesis 16 is implanted in the human or animal body, biological tissue will grow into the inner surface 10a of the wall 10f of the conduit 10. This is important to ensure that ingrowing biological tissue forms a pseudointima (an example of an inner biological tissue layer within a vascular prosthesis). Furthermore, in addition to the promotion of biological tissue growth on the inner surface 10a of the wall 10f of the conduit 10, it is also advantageous if the biological tissue layer growing on the inner surface 10a of the wall 10f of the conduit 10 has good adhesion to the inner surface 10a. If the adhesion between the biological tissue layer and the inner surface 10a is insufficient, complications can arise such as haemorrhagic dissection.
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(44) Prior to the addition of the masking agent 12 to the conduit 10, the conduit 10 is weighed. The weight of the conduit 10 is then used, at least in part, to determine the amount of masking agent 12 to add to the conduit 10.
(45) In this embodiment, the masking agent 12 is applied from a masking agent solution. The masking agent solution is a polymer solution. In the embodiment illustrated and described here, the polymer solution comprises approximately 7% w/v PVP (an example of a water-soluble polymer) in water (an example of a solvent). However, it should be understood that other polymers, such as glycerol, methyl cellulose and/or PEG could be used. Furthermore, it will be understood that the polymer solution could comprise between approximately 5% w/v PVP in solution and approximately 30% w/v PVP in solution. Moreover, the polymer solution could comprise between approximately 5% w/v polymer in solution and approximately 30% w/v polymer in solution. It should be understood that the masking agent 12 could comprise approximately 1% w/v of glycerol in solution. Without wishing to be bound by theory, it is thought that an advantage of adding glycerol to the masking agent 12 is that it mitigates cracking of the masking agent 12 when the masking agent 12 is added to the conduit 10.
(46) In the embodiment described here, the masking agent 12 comprises PVP with a molecular weight of approximately 10,000 g/mol. However, it should be understood that the masking agent 12 could comprise PVP with a molecular weight of between approximately 6,000 g/mol and approximately 15,000 g/mol.
(47) While in the embodiment described here the masking agent 12 comprises PVP, it should be understood that the masking agent 12 could comprise glycerol, methyl cellulose, PEG, PEO, and/or PEG hydrogel.
(48) In the embodiment illustrated and described here, the masking agent 12 is biocompatible. However, it should be understood that, in some embodiments the masking agent 12 need not be biocompatible. For example, as described in more detail below, if substantially all of the masking agent 12 is to be removed from the conduit 10, then the masking agent 12 need not be biocompatible. In some embodiments, the masking agent 12 need not be removed, and in some embodiments only a part of the masking agent 12 is removed. In these arrangements, it is advantageous that the masking agent 12 is biocompatible, which allows the conduit 10 to be implanted in the human or animal body.
(49) In this embodiment, the masking agent 12 is biodegradable. Therefore, any residual masking agent 12 present on the conduit 10 will biodegrade when the conduit 10 is implanted in the human or animal body. However, the masking agent 12 could be non-biodegradable. In this embodiment, substantially all of the masking agent 12 is removed from the conduit 10 prior to implantation, and therefore it is not necessary for the masking agent 12 to be biodegradable. In some embodiments, it may be advantageous for the masking agent 12 to be biodegradable.
(50) With reference to
(51) In this embodiment, the masking agent solution is applied to the conduit 10 by immersing the conduit 10 in the masking agent solution for approximately 1 minute, while agitating the conduit 10. However, it should be understood that the masking agent solution could be added to the conduit 10 in other ways, such as by dipping, spray coating, or by brushing. Furthermore, it should be understood that the masking agent 12 could be added to the conduit 10 without agitating the conduit 10. During the step of immersing the conduit 10 in the masking agent solution, the conduit 10 is moved between the contracted state and the extended state. However, it should be understood that the conduit 10 could be immersed in the masking agent solution while the conduit 10 is in the contracted state and/or the extended state.
(52) In this embodiment, when the masking agent solution is added to the conduit 10, solvent is then evaporated from the masking agent solution. Solvent is therefore removed from the masking agent solution, and the masking agent 12 remains on the conduit 10.
(53) In this embodiment, during the addition of the masking agent 12 to the conduit 10, a directed flow of air (an example of a gas) is provided to the conduit 10. The directed flow of air is directed towards the outer surface 10b of the wall 10f of the conduit 10, such that the masking agent 12 is preferentially formed on the inner surface 10a of the wall 10f of the conduit 10. It should be understood that while directed air flow is used here, other gases could be used.
(54) In this embodiment, the masking agent 12 is formed, or added, substantially on the inner surface 10a of the wall 10f of the conduit 10. However, it should be understood that the masking agent 12 could be added to the outer surface 10b of the wall 10f of the conduit 10. The masking agent 12 is added to the porous section 10e of the conduit 10, although in other embodiments the masking agent 12 could be added to at least a part of the porous section 10e of the conduit 10. In this embodiment, the masking agent 12 forms a masking agent layer substantially on the inner surface 10a of the wall 10f of the conduit 10. However, it should be understood that the masking agent 12 could be added to other parts of the conduit 10, and that the masking agent 12 could form a masking agent layer on other parts of the conduit 10.
(55) In the manufacturing process illustrated and described here, the residual masking agent 12 on the outer surface 10b of the wall 10f of the conduit 10 is removed prior to the addition of the sealant 14, in order to improve the adhesion between the sealant 14 (when applied to the conduit 10) and the outer surface 10b of the wall 10f of the conduit 10. In this embodiment, the residual masking agent 12 on the outer surface 10b is removed by ablating (an example of a first masking agent removal step). However, it should be understood that the masking agent 12 could be removed by applying a solvent, by heating, by etching, by plasma etching, by abrading, and/or by other techniques.
(56) In the embodiment shown in
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(58) When the sealant solution is applied to the conduit 10, solvent is evaporated from the sealant solution, which results in the formation of the sealant 14.
(59) While in the embodiment illustrated and described here the sealant 14 is added to the conduit 10 from a sealant solution, it will be understood that the sealant 14 could be added to the conduit 10 in other ways and need not be added from a sealant solution.
(60) The sealant 14 is added to the porous section 10e of the conduit 10. Therefore, in this embodiment, the sealant 14 is added to substantially all of the conduit 10, as in this embodiment the conduit 10 is entirely porous 10e. In other embodiments, the sealant 14 could be added to a part of the porous section 10e.
(61) The presence of the masking agent 12 prevents the sealant 14 from adhering, or forming on, the inner surface 10a of the wall 10f of the conduit 10. The sealant 14 is applied to the conduit 10 by spraying the sealant 14 onto the outer section 10b of the conduit 10. However, it should be understood that other techniques for adding the sealant 14 to the conduit 10 could be used, such as brushing, wiping, immersing, dipping, vapour depositing, such as chemical vapour depositing, electrostatic spinning, and/or by casting.
(62) In this embodiment, the sealant 14 is applied to the conduit 10, while the conduit 10 is in the extended state. However, it should be understood that the sealant 14 could be applied to the conduit 10 while the conduit 10 is in the contracted state or when the conduit 10 is moved between the contracted state and the extended state.
(63) In this embodiment, the sealant 14 is added to the conduit 10 while the conduit 10 is rotated about its longitudinal axis at approximately 60 rpm. However, it should be understood that the conduit 10 could be rotated about its longitudinal axis at up to approximately 2,000 rpm.
(64) In the embodiment described here, the sealant 14 comprises approximately 8 mg/cm.sup.2 of silicone. However, it should be understood that the sealant could comprise between approximately 4 mg/cm.sup.2 of silicone and approximately 19 mg/cm.sup.2 of silicone.
(65) Spraying and/or brushing the sealant 14 onto the outer surface 10b of the wall 10f of the conduit 10 is advantageous over some sealant application techniques because the sealant 14 is applied substantially only to the outer surface 10b of the conduit 10 and is not substantially applied to the inner surface 10a of the conduit 10. In this arrangement, the masking agent 12, and the addition of the sealant 14 to the conduit 10 by way of spraying, and/or brushing, the sealant 14 onto the conduit 10, mitigate presence of the sealant 14 on the inner surface 10a of the wall 10f of the conduit 10. However, it should be understood that other sealant 14 application techniques, such as wiping the sealant 14 onto the conduit 10, could be used.
(66) In the embodiment illustrated and described here, it is advantageous if, when the sealant 14 is applied to the conduit 10, the masking agent 12 is not substantially covered, or blocked, by the sealant 14. The reason for this is that, if at least a part of the masking agent 12 is to be removed from the conduit 10, it is easier to remove the masking agent 12 if at least some of the masking agent 12 is exposed. For example, when removing at least a part of the masking agent 12 from the conduit 10 by applying a solvent, it is easier to do so if at least some of the masking agent 12 is exposed. In the embodiments described here, a significant amount of the masking agent 12 is exposed, and it is therefore relatively straightforward to use a variety of masking agent 12 removal techniques.
(67) In this embodiment, the addition of the sealant 14 to the porous section 10e of the conduit 10 forms a sealing layer on the outer surface 10b of the wall 10f of the conduit 10. In this embodiment, the sealant 14 is biocompatible.
(68) In this embodiment, the sealant 14, when applied to the conduit 10, is configured to mitigate against environmental stress cracking.
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(70) In the embodiment described here and shown in
(71) In the embodiment depicted in
(72) In the embodiment illustrated and described here, the step of removing substantially all of the masking agent 12 from the conduit 10 does not result in the removal of the sealant 14 from the conduit 10.
(73) As described in detail above, the manufacturing process comprises a first masking agent removal step, designed to improve the adhesion of the sealant 14 to the conduit 10, and a second masking agent removal step, designed primarily to remove the masking agent 12 from the inner surface 10a of the wall 10f of the conduit 10. However, it will be understood that multiple masking agent removal steps could be carried out. It should also be understood that for some embodiments of the invention it may not be necessary to carry out a masking agent removal step.
(74) In the embodiment illustrated and described here, the vascular prosthesis 16 is reversibly sealable. That is, the sealant 14 could be removed from the conduit 10 and the sealant 14 could be applied to the conduit 10. For example, this could be necessary in the event of a manufacturing error. Similarly, the masking agent 12 may be added, and removed from, and subsequently added to the conduit 10. This could be necessary when carrying out more than one masking agent addition step.
(75) In the embodiment illustrated and described here, the vascular prosthesis 16 can be sterilised by way of a gamma sterilisation process. However, it should be understood that the vascular prosthesis 16 could be sterilised by way of an electron beam sterilisation process. Another option for sterilising the vascular prosthesis 16 is to carry out ethylene oxide sterilisation. It will be appreciated that other sterilisation techniques could be applied to the vascular graft 16, either as an alternative to, or in addition to those described here.
(76) The vascular prosthesis 16 depicted in
(77) The vascular prosthesis 16 illustrated in
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(79) The woven nature of the conduit 10 means that it is flexible. After applying the masking agent 12 and the sealing layer 14, the vascular graft 16 remains flexible, which helps to make the vascular graft 16 easier to manipulate and handle by, for example, a medical practitioner.
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(81) In the embodiment shown in
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(87) In the embodiment shown in
(88) One desirable feature for a sealed graft is that it may have sufficiently low levels of permeability to remain predominantly leak proof during the implant procedure. The applicable test method, as prescribed in ISO 7198, Whole Graft Permeability recommends testing using reverse osmosis (RO) filtered water at a test pressure of 120 mmHg. This parameter was based on a de facto standard established by the manufacturers of biologically sealed grafts (gelatin and collagen). A limit of 0.16 ml/min/cm.sup.2 may be used to ensure that the graft meets and exceeds sealing capability of aforementioned grafts. Different applications, however, may have different permeability requirements, and such different permeability requirements are within the scope of the present invention.
(89) Further embodiments were prepared according to the manufacturing process illustrated in
(90) Commercial textile vascular grafts were used for the tests described hereinafter. Details for commercial graft samples are described below:
(91) First Commercial Samples of Woven Graft Fabrics:
(92) (a) Warp yarn: twisted, texturized, PET, 2 ply/44 denier per ply (or bundle)/27 filaments per ply or bundle.
(93) (b) Weft yarn: twisted, texturized, PET, 2 ply/44 denier per ply (or bundle)/27 filaments per ply or bundle.
(94) (c) Picks per cm, about 40 to 46.
(95) Second Commercial Samples of Woven Graft Fabrics:
(96) (a) Warp yarn: 80 Denier, 2 ply/40 denier per ply (or bundle)/27 filaments per ply (or bundle), PET, Spun Draw, texturized, 7.5 Twists per inch, Z twist.
(97) (b) Weft yarn: 2 ply/40 Denier per ply (or bundle), 2 ply/40 denier per ply (or bundle)/27 filaments per ply or bundle, PET, TXT, S & Z Twist.
(98) (c) Picks per inch, about 155.
(99) The tests done below in Table 1 were performed on the first commercial samples of woven graft fabrics.
(100) TABLE-US-00001 TABLE 1 Sealant Sealant Leak Rate Masking Agent Sealant Coating Coverage Leak Rate ≤0.16 Polymer Solvent Polymer Solvent Method (mg/cm.sup.2) (ml/min/cm.sup.2) ml/min/cm.sup.2 7% w/v Water 30% w/v Xylene Brush x 1 11.33 0.19 No PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 1 8.30 0.19 No PVP Silicone 4% w/v Water TPU and THF Brush x 1 2.00 5.79 No PVP Silicone 4% w/v Water TPU and THF Brush x 2 3.70 0.46 No PVP Silicone 30% w/v Water 30% w/v Xylene Brush x 1 5.3 1.78 No PVP Silicone 30% w/v Water 30% w/v Xylene Brush x 1 5.2 3.49 No PVP Silicone 30% w/v Water 30% w/v Xylene Brush x 1 7.6 >12.24 No PVP Silicone 25% w/v Water 30% w/v Xylene Brush x 1 — — No PVP and Silicone 18% w/v Glycerol 7% w/v Water 30% w/v Xylene Brush x 1 4.8 0 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 8.9 0 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 3 8.3 0 Yes PVP Silicone 7% w/v Water 30% w/v Heptane Brush x 1 7.6 0.69 No PVP Silicone 7% w/v Water 30% w/v Heptane Brush x 2 13.8 0.02 Yes PVP Silicone 7% w/v Water 30% w/v Heptane Brush x 3 18.6 0 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 1 8.0 0.09 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 11.5 0.14 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 11.5 0.05 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 3 15.6 0 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 1 7.1 0.01 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 9.7 0.03 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 9.1 0.03 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 3 12.6 0.02 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 1 6.0 0.22 No PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 14.3 0.03 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 2 9.8 0.10 Yes PVP Silicone 7% w/v Water 30% w/v Xylene Brush x 3 13.8 0.06 Yes PVP Silicone 12% w/v Water 30% w/v Xylene Brush x 2 11.0 6.25 No PVP Silicone 12% w/v Water 30% w/v Xylene Brush x 2 11.3 1.81 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 3.5 7.24 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 2 5.6 0.07 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 3 5.3 0.57 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 6.7 5.11 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 8.7 0.01 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 6.4 0.02 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 4 8.41 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 6.3 8.99 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 3.8 5.05 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 8.1 1.17 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 7.9 0.14 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 8.2 5.94 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 8.8 1.08 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 11.4 0.01 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 6.8 5.93 No PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 7.4 0.16 Yes PVP Silicone 7% w/v Water 15% w/v Xylene Spray x 1 11.9 0 Yes PVP Silicone 6% w/v Water 15% w/v Xylene Spray x 1 7.8 0.04 Yes PVP and Silicone 1% w/v Glycerol
(101) A hobby spray gun was used for all spray application tests where sealants were sprayed onto graft samples. The spray distance from the graft samples was approximately 50 mm. Grafts were held horizontally on mandrel and rotated in a rotisserie. Spray rates were not measured but were controlled by a combination of the nozzle traverse rate (estimated at 2 seconds/cm), graft rotation speed (estimated between one and three revolutions per second) and overall spray volume rate. Craft bristle brushes were used for all brush application tests where sealants were brushed onto graft samples.
(102) As indicated in Table 1, if the wall 10f has a Leak Rate ≤0.16 ml/min/cm.sup.2 then the conduit 10 is considered suitable for implantation and is considered substantially impermeable. In some further embodiments, the masking agent 12 comprises glycerol. Without wishing to be bound by theory, the presence of glycerol in the masking agent 12 is thought to mitigate cracking of the masking agent 12 when applied to the conduit 10.
(103) Masking agents described herein prevent sealants, such as the liquid silicone elastomer dispersion, from penetrating throughout the thickness of the graft wall and reaching the lumen or blood contacting surface of the graft. Sealants, such as silicone, are believed to adhere to graft fibres on the external surface of the graft through two mechanisms: a. Where graft fibres have had the mask agent ablated or otherwise free of the masking agents, the liquid silicone elastomer dispersion adheres to the surface of the graft fibres, such as PET fibres. b. Where surface fibres are individually sheathed by the masking agent, these fibres are encapsulated and a mechanical interlocking takes place rather than surface adhesion.
(104) Silicone will adhere to the PET fibre surface where there is no masking agent, but will also encapsulate PET fibres which are sheathed in masking agent.
(105) The masking agent is believed to act like a slurry when applied to a textile and can flow and cover gaps between the yarn bundles and also seep between the yarn fibers. It acts as a viscous mixture moving through the fabric and settling and collecting at areas of low energy. Rather than attaching to individual fibers it continues to move and pool until a masking agent drying process initiates and through the evaporation of its solvent, such as water, the masking agent then solidifies wherever it has gathered.
(106) The elastomeric sealant (e.g., silicone) may not adequately attach to the textile surface where excessive concentrations of masking agent are present. If the masking agent is too viscous and has fully encapsulated an area of fabric and then dried, there may be no exposed yarn filaments for the silicone to mechanically encapsulate and lock onto. Without this mechanical encapsulation of the yarn by the silicone, then the adhesion may be poor and possibly non-existent once the masking agent is removed.
(107) While the masking agent may appear to thinly coat the individual filaments as it moves or washes through the textile, the concentrations remaining in these washed through areas after drying are not sufficient to prevent subsequent encapsulation and adhesion of the silicone adhesive to the yarn bundles.
(108) Any synthetic hydrophilic polymer and any biological hydrophilic polymer, e.g., gelatin, partially hydrolysed collagen, dextran, hyaluronic acid, alginates and starches (e.g., hydroxyethyl starch) and chitosan may be used as masking agents. Pluronic F127 PEG, which is soluble in cold water but insoluble in warm water, may also be used as a masking agent. Desirably, masking agents derived from animal products may are removed prior to vascular applications. As such, the masking agents, including animal derived masking agents, if any, are removed from the final product, such grafts may suitable be used in vascular applications. Furthermore, as the masking agents are removed from the textile graft prior to any applications with a patient, including vascular applications, the masking agents need not be biocompatible.
(109) Desirably, the masking agent is highly soluble in water. It can be any polymer which can swell in a liquid which has a Hildebrand Solubility Parameter (Delta SI units) of 24 or higher.
(110) Masking agents useful with the present invention may have molecular weights from about 400 or 1,000 to about 1,000,000. Desirably, the molecular weight may vary from about 3,000 to about 30,000, and more desirably from about 6,000 to about 15,000
(111) One useful sealant may be a dispersion of silicone in a nonpolar ‘solvent’ or carrier medium. Useful cross linking is through acetoxy ‘room temp vulcanisation’ chemistry but two part platinum cure chemistry could also be used as well as ultraviolet (UV) curing.
(112) For samples employing a polymer supplied as a dispersion, for example NuSil MED 6605 and Med 6606, discrete amounts of polymer dispersion were decanted by weight into individual pots for either direct coating onto the graft or further addition of solvent, by weight.
(113) All silicone dispersions used were acetoxy curing. Curing schedules are recommended at 72 hours, however due to the extremely thin cross section/large surface area of the graft, full cures have been observed apparent within 24 hours. Subsequent washing of the device in water may speed up the curing and ensure full cross linking. These times are, however, non-limiting, and other cure times and conditions may suitably be used.
(114) The preferred polymers for coating, in order to achieve a soft and flexible graft with handling characteristics similar to that of a gelatin sealed graft, are those with very low Shore hardness values. The preferred silicone elastomers, MED 6605 and MED 6605 have Durometer Type A values of 25 and 20 respectively. Both of these grades can provide grafts with suitable flexibility and handling characteristics, when thin coatings are applied. As multiple coatings are applied, stiffness may increase and flexibility may reduce.
(115) Harder grades can be used as an alternative to thicker coatings in order to create stiffer grafts if required.
(116) Alternative coatings, such as TPU-Silicones (Advansource Chronosil 75A or Aor-Tech Elast-Eon E5-130) can be used however, these have Durometer Hardness of 75A and 77A respectively, therefore may create grafts which may be stiffer, if desired, than current gelatin sealed grafts. Such stiffer grafts may have some benefits for specific applications, however, may not meet expectations for conventional surgeon handling.
(117) Additional useful sealant materials include, but are not limited to:
(118) (a) Applied Silicone Corporation, PN 40021, Implant grade high strength RTV Silicone Elastomer Dispersion in Xylene. This material is suitable for use in fabricating high strength, elastic membranes of any shape and thickness using processes such as dipping, casting, spraying or brushing. After evaporating the solvent, the silicone is room temperature vulcanized (RTV) by exposure to ambient air. The key features of this material are high strength, low durometer, (Shore A 24) and is supported by ISO 10993 testing and compendium to support regulatory submissions.
(b) AdvanSource Biomaterials Corporation, ChronoFlex AR, polycarbonate based thermoplastic urethanes. These materials may be used for moulding, casting and dip-coating and are fully synthesized in liquid providing high strength & elongation while maintaining the inherent polycarbonate advantage of long-term permanent durability and resistance to environmental stress cracking (ESC). Additionally, they may be electrospun or used in water emulsion processes. Examples of specific useful materials include, but are not limited to, ChronoFlex C80A 5% and ChronoFlex AR 23%.
(119) Suitable sealants are low durometer elastomers (desirably less than or equal to about 40A durometer or shore hardness 40A, more desirably less than or equal to about 30A durometer or shore hardness 30A, even more desirably less than or equal to about 20A durometer or shore harness 20A) and have good biostability.
(120) One parameter which may be considered in the choice of sealant is the stiffness or elastic modulus. Usually with elastomers the modulus is not linear thus at each elongation the stress (or force) is measured. A material with lower stress @ % strain will provide less resistance to extension and will therefore feel more flexible and closer to matching the handling of a gelatin sealed graft.
(121) Preferred materials are low stress silicone rubbers, such as NuSil MED 6605 and MED 6606, with Stress @ Strain values <180 @ 200%.
(122) Useful Polyurethane and Silicone-polyurethane grades, include, but are not limited to:
(123) TABLE-US-00002 TABLE 2 Stress (psi) at % Material Manufacturer Grade elongation Silicone NuSil MED 6606 50 @ 100% Rubber Silicone NuSil MED 6605 160 @ 300% Rubber Silicone Applied Dispersion PN 170 @ 300% Rubber Silicone 40021 TPU-Silicone Advansource ChronoSil 570 @ 200% adjusted TPU-silicone Biomerics Quadrasil Elast- 725 @ 200% EON E5-130 TPU-aliphatic Advansource Chronoflex AL 800 @ 200% polycarbonate 75A TPU-10% Advansource ChronoSil 75A 834 @ 200% silicone 10% Si
(124) The present invention is not limited to the use of silicone as the polymeric sealant. Other useful coating materials for both medical and non-medical textiles may include, for example, polytetrafluoroethylene, polyethylene, poly(hydroxyethly methacrylate), poly(vinyl alcohol), polycaprolactone, poly(D, L-lactic acid), poly(L-lactic acid), poly(lactide-co-glycolide), poly(hydroxybutyrate), poly(hydroxybutyrate-co-valerate), polydioxanone, polyorthoester, polyanhydride, poly(glycolic acid), poly(glycolic acid-cotrimethylene carbonate), polyphosphoester, polyphosphoester urethane, poly(amino acids), cyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate), copoly(ether-esters), polyalkylene oxalates, polyphosphazenes, polyiminocarbonates, aliphatic polycarbonate, polyethylene oxide, polyethylene gylcol, poly(propylene oxide), polyacrylamide, polyacrylic acid (30-60% solution), polymethacrylic acid, poly(N-vinyl-2-pyrollidone), polyurethane, poly(aminoacid), cellulosic polymer (e.g. sodium carboxymethyl cellulose, hydroxyethyl celluslose), collagen, carrageenan, alginate, starch, dextrin, gelatin, poly(lactide), poly(glycolide), polydioxanone, polycaprolactone, polyhydroxybutyrate, poly(phospazazene), poly(phosphate ester), poly(lactide-co-glycolide), poly(glycolide-co-trimethylene carbonate), poly(glycolide-co-caprolactone), polyanhydride, polyamide, polyesters, polyether, polyketone, polyether elastomer, parylene, polyether amide elastomers, polyacrylate-based elastomer, polyethylene, polypropylene, and/or and derivatives thereof. Other useful coating materials, in particular for but not limited to non-medical textiles, may include natural rubbers, natural gums, acrylic polymers, polybutadienes, styrene-butadiene copolymers or rubbers, butadiene-acrylonitrile copolymers, polyisobutylenes, isoprene-isobutylene copolymers, polysulfide rubbers, chloroprene rubbers (neoprene), chlorosulfonated polyethylene, fluorinated polymers, vinyl resins, and the like. Further, coating materials may include metallic materials and powdered materials.
(125)
(126) The support member 18 is a flexible, polymer wire, which in this embodiment is wrapped around the outer surface 10b of the wall 10f of the conduit 10 and is arranged to nest between the crimps 10g of the conduit 10. One of the advantages of adding the support member 18 to the conduit 10, as illustrated and described here, is that the conduit 10 is made more robust while retaining much of its flexible characteristics. As stated above, the conduit 10 is able to be manipulated by a medical practitioner in a more efficient way because the conduit 10 is flexible.
(127) In the embodiment illustrated in
(128)
(129) An example of how the vascular graft 16 may be used will now be provided.
(130) The vascular graft 16 described in
(131) The masking agent 12 is configured to biodegrade in the body. Therefore, any residual masking agent 12 present on the conduit 10 will biodegrade in the body. However, as described in more detail above, the masking agent 12 need not be biodegradable, as in some embodiments the masking agent 12 will be removed substantially entirely from the conduit 10. In other embodiments, the masking agent 12 need not be removed from the conduit 10.
(132) The vascular graft 16 can be used to bypass a region, or a section of a blood vessel. For example, if a medical practitioner identifies a blocked, a diseased region or partially blocked region of a blood vessel, they may decide to bypass that region by using the vascular graft 16. In this example, the inlet 10c of the vascular graft 16 may be attached to one point of the blood vessel, and the outlet 10d of the vascular graft 16 may be attached to another point of the blood vessel. In another example, the blood vessel could be diseased, or have been severed or bisected in order to connect the vascular graft 16 to two ends of the severed blood vessel. Because the vascular graft 16 is sealed, blood may flow through the vascular graft 16 in order to bypass the blocked, diseased, or partially blocked region of the blood vessel, and the leaking of blood through the walls 10f of the conduit 10 is mitigated by the presence of the sealant 14.
(133) Once the vascular graft 16 is in place, biological tissue will grow into the inner section 10a of the vascular graft 16 in order to form a pseudointima. Over time, the psuedointima will form, adhering to the inner section 10a of the vascular graft 16. During this time, the vascular graft 16 prevents leakage of blood through the wall 10f and acts as a scaffold for the ingrowing biological tissue.
(134) The vascular graft 16 may also be used to connect a further prosthesis, such as a heart assist device, a biological heart valve or a synthetic heart valve, to a blood vessel. For example, the inlet 10c of the vascular graft 16 may be connected to an outlet of a synthetic heart valve, and the outlet 10d of the vascular graft 16 may be connected to an end of a blood vessel. The advantage of this use of the vascular graft 16 is that a heart assist component can be used with a wide variety of shapes and sizes of blood vessels, as the vascular graft 16 can be provided in a range of sizes. The medical practitioner is then able to select which particular vascular graft 16 will interface well with the synthetic heart valve and the blood vessel. This avoids the need for a range of different configurations of heart assist device to be used, as a standard part can be used and customised by adding different types and sizes of vascular graft 16. It will be appreciated that, depending on the nature of the heart assist device, multiple vascular grafts 16 could be used with the heart assist device.
(135) While the embodiments illustrated and described here show a cylindrical conduit 10 with an inlet 10c and an outlet 10d, other shapes of conduit 10 could be used. For example, a Y shaped, T-shaped, or a multi-channel conduit 10 could be used.
(136)
(137) The mandrel 20 may be used for a variety of purposes. For example, the mandrel 20 could be used to deliver the masking agent or the water-soluble material to a tubular textile, such as a graft. In such a use, a tubular textile (not shown) may be disposed over the outer surface 22 of the mandrel 20. The masking agent or the water-soluble material may be delivered into the open lumen 24 of the mandrel 20, for example into the open lumen 24 via an open end 25. The opposed end may be closed or open, such as in the case of a circulating system for the fluid masking agent or water-soluble material. The fluid masking agent or water-soluble material would flow through the perforations or holes 23 and onto and into the graft (not shown) disposed over the mandrel 20.
(138) The mandrel 20 may have a controlled amount of fluid masking agent or water-soluble material within the lumen 24 to control the amount of fluid masking agent or water-soluble material exposed to the graft (not shown). The fluid masking agent or water-soluble material contained within the mandrel 20 may be forced onto the graft through the use of a pressure differential (higher pressure within the lumen 24 than outside the lumen 24) or through rotational forces when the mandrel 20 is disposed on or within a rotating or spinning device.
(139) A mandrel not having the perforations 20 (not shown) may be used to dispose a layer of fluid masking agent or water-soluble material over the outer surface of the mandrel. The masking layer may be viscous enough or partially cured to remain on the mandrel until a graft is disposed over the mandrel. The masking layer may then be releasably disposed over the inner surface of the graft.
(140) The mandrel 20 may also be used for control of fluid migration. For example, the pressure within the lumen 24 may be lower than the pressure outside of the lumen 24. Such a negative pressure or vacuum may be used to migrate the masking agent or water-soluble material away from the outer surface of a graft (not shown).
(141) The mandrel 20 may also be used for drying the fluid masking agent or water-soluble material. A warm gas, such as air, may be introduced into the lumen 24, flow through the perforations or holes 23, and dry the fluid masking agent or water-soluble material. Alternatively, a heat source may be disposed outside of the mandrel 20, and the flow of heat, such as heated air, may be controlled through the application of a negative pressure at the lumen 24.
(142) A mandrel, either the same or different, may be used throughout different applications and techniques described herein, such as, but not limited to, masking agent application and/or dispersion, masking agent drying, sealant application and/or dispersion, sealant drying and/or curing, textile washing, and the like. A tubular textile may be substantially disposed over a mandrel or only a portion of the tubular textile may be disposed over a mandrel. For example, one end of a tubular textile may be supported by a mandrel and the other end of the tubular textile may be supported by a different mandrel, and the like.
(143) The substantially water-insoluble sealant may also be applied to the graft while the graft is on a solid or non-perforated mandrel or on a perforated mandrel 20. The substantially water-insoluble sealant may be applied to the graft by any suitable means, such as by brushing, spraying, roller coating, spinning the substantially water-insoluble sealant thereon.
(144) Furthermore, if desired the substantially water-insoluble sealant may be cured with the graft disposed over a mandrel.
(145) Further, other materials, such as colorants, therapeutic agents, dyes, fluorescent indicators, and the like maybe applied to the graft.
(146) Therapeutic agents may include, but are not limited to: anti-thrombogenic agents (such as heparin, heparin derivatives, urokinase, and PPack (dextrophenylalanine proline arginine chloromethylketone); anti-proliferative agents (such as enoxaprin, angiopeptin, or monoclonal antibodies capable of blocking smooth muscle cell proliferation, hirudin, and acetylsalicylic acid); anti-inflammatory agents (such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine); antineoplastic/antiproliferative/anti-miotic agents (such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones, endostatin, angiostatin and thymidine kinase inhibitors); anesthetic agents (such as lidocaine, bupivacaine, and ropivacaine); anti-coagulants (such as D-Phe-Pro-Arg chloromethyl keton, an RGD peptide-containing compound, heparin, antithrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors and tick antiplatelet peptides); vascular cell growth promoters (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional activators, and translational promotors); vascular cell growth inhibitors (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of an antibody and a cytotoxin); cholesterol-lowering agents; vasodilating agents; agents which interfere with endogenous or vascoactive mechanisms; and combinations thereof.
(147) Masking Agent Drying and Uniformity Tests
(148) Tests were performed to determine how long it took for a standard woven graft immersed in PVP to dry at different concentrations, and if PVP dried in a homogeneous fashion throughout the textile. A series of tests at different concentrations of PVP were done to determine if the concentration made a difference on the drying nature of the substance.
(149) The tests used 15%, 10% & 5% PVP solution profiles. First, a 15% solution of PVP was made with 15 g of PVP and 100 mL of water. This was agitated until PVP was fully dissolved into solution. Graft samples were prepared by cutting approximately 50 mm of a commercial tubular graft. The graft samples were, if necessary, dried and were weighed. Graft samples were then soaked in the 15% PVP solution. The wet grafts were weighed to provide initial weights. The samples were placed vertically near a running fan. The graft samples were weighed at 5-minute intervals until there was a constant weight being displayed. The graft samples were cut into 4 labelled pieces. Each quarter piece was weighed. The quarter pieces were then washed, dried, re-weighed when fully dry. The lengths of the dry-washed graft were measured.
(150) Next, 50 mL of water was added to the 15% PVP solution in order to make a 10% PVP solution. The above textile processing steps were repeated for the 10% PVP solution
(151) Next 150 mL of water was added to the 10% PVP solution to make a 5% PVP solution. The above textile processing steps were repeated for the 5% PVP solution.
(152) Results: 15% PVP Profile
(153) TABLE-US-00003 TABLE 3 Time Weight (min) (g) Dry 1.709 0 4.817 5 4.229 10 3.81 15 3.399 20 3.056 25 2.775 30 2.543 35 2.36 40 2.235 45 2.152 50 2.122 55 2.117 60 2.113 65 2.113 Length Length measured (mm) Initial 51 Final 52 Quarter With PVP Without PVP wt % PVP in piece 1 0.507 0.418 17.6 2 0.519 0.421 18.9 3 0.569 0.461 19.0 4 0.516 0.427 17.2 Total 2.111 1.727 18.2 Total expected 2.113 1.709
(154) Table 3 showed that the 15% PVP coated graft took over an hour to dry fully in ambient air, it also showed that there was a slight increase in the length of the graft after being coated, washed and dried. After drying, the samples averaged 18.2 weight percent PVP. Further, the distribution of PVP among the samples was substantially consistent. Graft samples or pieces 2 and 3 had slightly higher PVP levels. These pieces had a seam of the graft on them, so it appeared that the seam was probably absorbing more PVP. Thus, about 15 to about 21 weight percent PVP was deposited onto the graft when immersed in the 15% PVP solution.
(155) Results: 10% PVP Profile
(156) TABLE-US-00004 TABLE 4 Time Weight (min) (g) Dry 1.699 0 4.891 5 4.292 10 3.881 15 3.491 20 3.159 25 2.849 30 2.580 35 2.124 40 2.040 45 2.000 50 1.994 55 1.994 Length Length measured (mm) Initial 48 Final 51 Quarter With PVP Without PVP wt % PVP in piece 1 0.543 0.469 13.6 2 0.598 0.51 14.7 3 0.394 0.334 15.2 4 0.459 0.394 14.2 Total 1.994 1.707 14.4 Total expected 1.994 1.699
(157) Table 4 showed that the 10% PVP covered graft took just under an hour to dry completely, and that the 10% PVP solution covering, washing and drying had also caused a slight increase in the length of the graft. The slightly higher weight % of PVP in pieces 2 and 3 also suggested that the seam of the graft absorbed more of the PVP than the rest of the graft. After drying, the samples averaged 14.4 weight percent PVP. Thus, about 10 to about 18 weight percent PVP was deposited onto the graft when immersed in the 10% PVP solution.
(158) Results: 5% PVP Profile
(159) TABLE-US-00005 TABLE 5 Time Weight (min) (g) Dry 1.514 0 3.197 5 2.735 10 2.385 15 2.070 20 1.820 25 1.650 30 1.590 35 1.588 40 1.588 Length Length measured (mm) Initial 47 Final 47 Quarter With PVP Without PVP wt % PVP in piece 1 0.357 0.348 2.5 2 0.423 0.406 4.0 3 0.432 0.412 4.6 4 0.371 0.354 4.6 Total 1.583 1.52 4.0 Total expected 1.588 1.514
(160) Table 5 showed that the 5% PVP covered graft took the least time to dry completely, and that its length did not seem to alter after coating, washing and drying, the PVP did to a minor degree to ‘sink’ to the bottom of this graft. Thus, about 2 to about 8 weight percent PVP was deposited onto the graft when immersed in the 5% PVP solution.
(161) Conclusions
(162) The 15% PVP covered graft took the most time to dry by approximately 25 minutes. In terms of drying evenly anyone of these concentrations was acceptable.
(163) Various drying techniques are suitable for use with the present invention. For example, textile grafts and/or textile substrates may be dried at room temperature to remove the solvent(s) from the deposited masking agent solution and/or from the sealant solution. Forced air, such as use of a fan or fans or other sources of air movement and/or sources of pressurized air, may be used to facilitate drying. The forced air, if any, may be applied at any suitable angle or combination of angles. The air may or may not flow into the interior lumen of the graft. For example, forced air may be directed towards outer surface of a tubular graft, either perpendicularly, substantially perpendicularly, at an acute angle, and/or at an obtuse angle. Moreover, forced air may be directed towards the interior lumen of the tubular graft, such as towards one open end of the tubular graft, or even from within the interior lumen of the tubular graft. The direction of air flow and the amount of extend of the air flow may be varied to control drying times and even to control resultant physical properties of the graft. Forced air flow may also be useful in aiding migration of the masking agent towards the interior portions of the graft and away from exterior portions of the graft. In other words the masking agent desirably retracts when drying. This would aid in the securement of the sealant material at the exterior portions of the textile graft while also aiding in the blocking of sealant migration towards the interior portions of the graft. The present invention, however, is not limited to the use of air as a drying medium, and other suitable media, including gaseous media, may be used. Further, the present invention is not limited to room temperature drying, and elevated drying temperatures above room temperature may suitably be used.
(164) Moreover, a fluid, such as water, including heated water, may be used with the present invention as described below. The use of heated water aids in the removal of the water-soluble masking agent from the textile product. Further, the use of heated water may also aid in curing of the sealant or sealing agent.
(165) Furthermore, drying and/or curing the sealant material may also be controlled using forced air or other medium, ambient forced air or other medium, heated forced air or other medium, non-forced ambient air or other medium, non-forced heated air or other medium, and the like. Not only may curing times of the sealant material be controlled, but also, to some extent, the properties of the sealant layer may be controlled. The sealant material may be selected, dried or cured, and or selectively deposited, such that the sealant material, as is cures, shrinks about the textile substrate, e.g., the outer surface of the textile graft.
(166) Masking Agent Removal Tests
(167) Different washing methods for the grafts were performed to determine which method would extract the highest levels of PVP and if the chosen method has any effect on the length and crimp of the graft.
(168) Two wash processes were considered, an Ultrawave ultrasonic bath and a domestic washing machine.
(169) Procedures
(170) Part 1: No Sealant Coating
(171) This trial was first done on 6 grafts that were not coated with silicone in order to establish if 100% of the PVP could be removed with the chosen washing methods.
(172) Grafts were prepared by cutting approximately 6×60 mm lengths of commercial woven grafts. All 6 grafts were measured, weighed, and labelled with notches cut into the side. A 15% PVP solution was made with 15 g of PVP and 100 mL of water. All 6 samples were submerged in the 15% PVP in solution. All 6 samples were dried vertically near a running fan. All dried samples were weighed.
(173) An ultrasonic bath was set to 40 degrees Celsius. Samples 1, 2, and 3 were submerged into the ultrasonic bath. Samples 1-3 were left in the ultrasonic bath for 15 minutes. These samples were removed from the ultrasonic bath and were dried vertically near a fan. The dried 1-3 samples were weighed and their lengths were measured and recorded.
(174) Samples 4, 5, and 6 were placed in a washing bag and then into a washing machine. The washing machine was set to a 40 degrees Celsius, 800 RPM, 51 minute wool wash setting. Samples 4-6 were removed from the washing machine and were allowed to dry. Samples 4-6 were weighed and their lengths were recorded.
(175) Part 2: Silicone in Heptane Sprayed Sealant Coating
(176) Samples 1-3 were re-washed, dried, measured and weighed. Samples 1-3 were then submerged in the 15% PVP solution. All 6 samples were dried vertically near a running fan. The dried samples were weighed.
(177) All 6 samples were stretched out and sprayed with silicone in heptane coating. The 6 samples were then allowed to return to their relaxed states under a fume hood and were allowed to dry. An ultrasonic water bath was set to 40 degrees Celsius. Once dry, samples 1-3 were submerged in the ultrasonic bath for 15 minutes. These samples were removed from the bath and were dried vertically near a fan. The dried samples 1-3 were weighed, and their lengths were measured and recorded.
(178) Once dry, samples 4-6 were placed in a washing bag and then into a washing machine. The washing machine was set to a 40 degree Celsius, 800 RPM, 51 minute wool wash setting. The samples were removed from the washing machine and were allowed to dry. Once dry, the samples 4-6 were weighed, and their lengths were measured and recorded.
(179) Results
(180) TABLE-US-00006 TABLE 6 No Sealant Coating Ultrasonic Bath Washing Machine at 40 Degrees Wool Setting Sample Sample Sample Sample Sample Sample Measurement 1 2 3 4 5 6 Initial 2.747 3.177 2.456 2.641 2.772 2.846 Weight (g) Dried PVP 3.508 4.048 3.179 3.445 3.568 3.658 weight (g) Washed 2.779 3.212 2.467 2.641 2.772 2.847 Weight (g) PVP 0.032 0.035 0.011 0.000 0.000 0.001 left (g) Initial 62.5 61 57 57 56 63.5 Length (mm) Final 62.5 62 57 57 56 63.5 Length (mm)
(181) The majority of the samples that were put in the washing machine were cleared of PVP while the samples that were put in the ultrasonic bath all still had some minor PVP on them after washing.
(182) TABLE-US-00007 TABLE 7 Silicone in Heptane Sprayed Sealant Coating Ultrasonic Bath at 40 Degrees Washing Machine Wool Setting Measurement Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Initial Weight 2.747 3.177 2.456 2.641 2.772 2.847 (g) Dried PVP 3.510 3.911 3.123 3.389 3.538 3.57 weight (g) Dried PVP + 3.737 4.08 3.323 3.583 3.843 3.825 Coating weight (g) Washed 2.779 3.212 2.467 2.641 2.772 2.847 Weight (g) Silicone 0.227 0.169 0.200 0.194 0.305 0.255 applied (g) PVP + silicone 0.252 0.186 0.214 0.206 0.312 0.266 left on graft (g) PVP left (g) 0.025 0.017 0.014 0.012 0.007 0.011 Initial Length 62.5 61 57 57 56 63.5 (mm) Length after 81 79 73 79 79 79 coating (mm) Final Length 70 66 62 61 64 65 (mm) Ratio of PVP 3.4 4.3 3.3 3.9 2.5 2.8 Applied to Silicone Applied, wt./wt. Ratio of 0.29 0.23 0.30 0.26 0.40 0.36 Silicone Applied to PVP Applied, wt./wt. Percent PVP 96.7 97.7 97.9 98.4 99.1 98.5 Removed, wt. %
(183) Although there was some PVP left on the grafts that went in the washing machine, there is significantly less PVP left on them as opposed to the grafts washed in the ultrasonic bath. In all cases, greater than about 90 weight percent of the PVP was removed. Indeed, in all cases greater than about 95 weight percent of the PVP was removed.
(184) In Table 7, the weight ratio of PVP to silicone applied varied from about 2.5:1.0 to about 4.3:1.0. Conversely, the weight ratio of silicone to PVP applied varied from about 0.40:1.0 to about 0.23:1.0.
(185) Further, ratios are described in Table 11 below.
(186) The ratios described in Tables 7 and 11 are non-limiting.
(187) The weight ratio of PVP (or other masking agents) to silicone (or other sealant agents) may vary from about 10:1 wt. PVP (or other masking agents)/wt. silicone (or other sealant agents) to about 0.01:1 wt. PVP (or other masking agents)/wt. silicone (or other sealant agents), desirably from about 1:1 wt. PVP (or other masking agents)/wt. silicone (or other sealant agents) to about 0.05:1 wt. PVP (or other masking agents)/wt. silicone (or other sealant agents), more desirably from about 0.5:1 wt. PVP (or other masking agents)/wt. silicone (or other sealant agents) to about 0.1:1 wt. PVP/wt. silicone.
(188) Conversely, the weight ratio of silicone (or other sealant agents) to PVP (or other masking agents) may vary from about 0.1:1.0 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents) to about 100:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents, desirably from about 1:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents to about 20:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents, more desirably from about 2:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents to about 10:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents.
(189) Mask and Dye Tests
(190) Materials
(191) Fabric—Diameter 22 mm, flat tube twill weave and Diameter 10 mm. Crimped twill weave.
(192) Silicone—NuSil Med16-6606 (Temporary implant grade).
(193) Solvent—n-Heptane, 50:50 with silicone dispersion.
(194) Dye—Easy Composites Royal blue pigment for RTV silicone, mixed to approx. 10% of silicone solid content.
(195) Sample Description
(196) For Flat 22 mm fabric samples, the following masking agent formulations were used:
(197) #71 A—Bare Fabric
(198) #71B—6% PVP
(199) #71C—6% PVP+1.5% Glycerol (by volume of Mask solution)
(200) #71D—6% PVP+1.5% Glycerol+4% PVP (Total 10% PVP)
(201) The #71B-D flat fabric samples were immersed into the PVP solution and then removed. All #71 samples were mounted on suspended mandrels (Post masking, Pre-coating).
(202) For Crimped Diameter 10 mm fabric samples, the following masking agent formulations were used:
(203) #70 A—Bare Fabric
(204) #70B—6% PVP
(205) #70C—6% PVP+1.5% Glycerol (by volume of Mask solution)
(206) #70D—6% PVP+1.5% Glycerol+4% PVP (Total 10% PVP)
(207) The #70B-D crimped fabric samples were immersed into the PVP solution and then removed. All #70 samples were mounted on suspended mandrels (Post masking, Pre-coating).
(208) Masking Agent Preparation
(209) Masking agents were prepared using the same method as described above, with the additional steps to add glycerol for samples B and C (both #70 and #71) and then additional PVP for samples D (both #70 and #71).
(210) Measured the target weight of PVP into plastic beaker on scale balance. A 100 ml masking agent solution was prepared therefore target mass of 4 g PVP required (4% concentration). Measured the target volume of de-ionised water into a 100 ml plastic measuring cylinder. A 100 ml Mask solution to be prepared therefore target volume of 96 ml required. Added de-ionised water into the PVP in plastic beaker. Placed magnetic stirrer in the water and place the beaker on the magnetic stirrer. Turned the magnetic stirrer on at a speed of 350-450 RPM, ensuring the stirrer is centred in the beaker. The stirring was done at room temperature. Stirring was continued until there was no visible PVP solute, or for a minimum of at least 2 minutes. After stirring the masking agent solution was removed from stirrer and used for graft preparation, samples B.
(211) Additional steps were used for samples C, i.e. added glycerol. Returned the plastic beaker to scale balance, tared, and added required quantity of glycerol to the mask agent solution. The target glycerol content was 1.5% by volume of masking agent solution. This corresponded to a target weight of 1.5 g. (Note this corresponded to 25% Glycerol to PVP). Set beaker on stirrer and stirred for at least 2 minutes. This masking agent solution used for samples C.
(212) Additional steps were used for samples D, i.e., additional PVP. Returned the plastic beaker to scale balance, tared, and added the required quantity of PVP to the masking agent solution. The target PVP content was 10% by volume of Mask solution. This corresponded to an additional 4 g PVP added. (Note this effectively reduced the glycerol to PVP ratio from 25% to 15%). This masking agent solution was used for samples D.
(213) Sealant Preparation
(214) The silicone sealant dispersion as-supplied had a 30% solid content, the dispersion was diluted by an additional 100% of solvent. This reduced the solid content to 15%. Additionally, a blue dye was added to the silicone dispersion to provide a visual indication of the coverage and depth of penetration of silicone into the fabric structure.
(215) In particular, 20 ml of silicone dispersion was measured out from its container, in the as-supplied state, and placed into a plastic beaker. An additional 20 ml of n-Heptane solvent was added. The mixture was beaked and was set on scales, tared, and drops of dye were added using dropper. The recommended dye concentration range was 0.3% to 5%, depending of section thickness, therefore a target of 5% was set in order to provide a strong blue colour for visualization. A deviation from this target was due to a calculation of the solid content being at 30% rather than 15%, therefore the actual concentration of dye to silicone was 10% rather than 5%.
(216) Sample Preparation
(217) The individual samples were prepared with masking agent formulations according to the following table.
(218) TABLE-US-00008 TABLE 8 6% PVP + 10% PVP + No 6% Glycerol Glycerol Mask PVP (@25% of PVP) (@15% of PVP) Flat Fabric 71A 71B 71C 71D Crimped 70A 70B 70C 70D Fabric
(219) Samples B-D were immersed in the mask agent solution, as per the above table. The samples were assembled onto mandrel such that each fabric was held at diameter by sized end bungs, but remained unsupported on the inner surface. The inner surface of each fabric was not in contact with the mandrel to avoid affecting mask performance, location and concentrations.
(220) Dispersion drop assessment was undertaken as described below.
(221) Each sample was fully coated with at least 2 coats of silicone dispersion. The intention was to ensure sufficient silicone was present on the outer surface to effect a suitable coverage without concerns for lack of silicone during visual evaluations. Brush coating was done onto a rotating graft on rotisserie at approximately one revolution per second. Grafts were left overnight for solvent evaporation. Grafts were left to fully cure for recommended 72 hrs before being removed from mandrel for washing. The grafts were then placed in a delicate bag and put on 95° C. Tumble Machine Wash cycle for approximately 2 hours 30 mins.
(222) Samples were masked, coated, washed and cut opened flat.
(223) Dispersion Drop Assessment
(224) Prior to full coating, a single drop of polymer dispersion was applied to each sample, and video recorded in order to visually assess if there were noticeable differences in the behaviour of the dispersion on the masked fabric.
(225) Sample A—No Mask. Slow spread of the single drop of polymer dispersion across fabric. Appeared to be soaking into and through fabric
(226) Sample B—6% PVP Mask. Rapid spread of the single drop of polymer dispersion across fabric. Appeared to spread more readily than soaking into and through fabric
(227) Sample C—6% PVP+1.5% Glycerol Mask. First drop of the single drop of polymer dispersion had rapid spread across fabric. The second drop of the single drop of polymer dispersion was inconclusive, possibly due to sagging fabric holding the pool.
(228) Sample D—10% PVP+1.5% Glycerol Mask. Inconclusive-possibly due to sagging fabric holding the pool
(229) Dispersion Drop Assessment across face of the graft:
(230) Sample A—No Mask. Slower spread of the single drop of polymer dispersion across fabric. Appeared to soak into fabric.
(231) Sample B—6% PVP Mask. Rapid spread of the single drop of polymer dispersion across fabric. Coverage was more uneven with pooling of dispersion in valleys.
(232) Sample C—6% PVP+1.5% Glycerol Mask. Fabric clearly resisted dispersion soaking in.
(233) Sample D—10% PVP+1.5% Glycerol Mask. Fabric clearly resisted dispersion soaking in.
(234) In summary, this Dispersion Droplet Assessment showed that even the lower concentration of masking agent, (Samples B, 6% PVP), appeared to initiate a significantly different response when compared to a non-masked fabric.
(235) A “pooling” effect was seen on the flat fabrics, samples 71C, 71D, was most likely a result of the excess dispersion being unable to run off the fabric or through the fabric. This effect was perhaps also evident in the crimped fabric, particularly Samples 70B, 70D, where there was pooling of the dispersion in the valleys, highlighted by the darker colour, unlike the non-masked sample 70A, which appears far more uniform in colour/coverage.
(236) Assessment of Sealant Coverage and Penetration
(237) Following the wash cycle to remove the masking agent the grafts were cut lengthways to provide visualization of inner and outer surfaces. Each graft was visualized under optical microscopy on: (a) the outer surface—to confirm presence and uniformity of sealant coating; (b) the inner surface—to confirm presence or ingress of blue silicone, either through the fabric or between the yarn filaments; and (c) sectional view—to assess the level of penetration through the yarn bundles.
(238) Results
(239) Both samples without mask appeared to have permitted the dyed blue silicone dispersion into the yarn bundles and penetrate to the inner surface while the application of the mask appears to have prevented this ingress on all samples.
(240) TABLE-US-00009 TABLE 9 Penetration of Polymer to Mask Applied Inner Surface Flat Fabric Samples 71A None Yes 71B 6% PVP No 71C 6% PVP + Glycerol No 71D 10% PVP + Glycerol No Crimped Fabric Samples 70A None Yes 70B 6% PVP No 70C 6% PVP + Glycerol No 70D 10% PVP + Glycerol No
(241) Photographs of crimped fabric sample 70D are provided in
(242)
(243) The masking agent solution may encapsulate whole yarn bundles and individual yarn fibers, depending on the concentration of the masking agent solution. The higher concentrated masking agent solution (i.e. >30% w/w PVP, >20% w/w of PVP glycerol in water) seems to be too thick to flow into the yarn bundles and coat individual fibers, as seen in
(244) The overall mechanism of masking agent may include two main concepts, depending on the size of the void or gap: (1) a physical effect for macro pathways (i.e. voids between yarn bundles) and (2) chemical effect for micro pathways (i.e. voids between fibers and voids in micro cracks within the masking layer).
(245) (1) Physical Effect: Filling macro pathways is based on the physical ability for the masking agent solution to penetrate and flow into large voids between the yarn bundles. When the yarn bundles are completely encapsulated with a masking agent layer, the masking agent layer fills the voids between each yarn bundle and blocks entry into the yarn bundle. In turn, the sealant would not be able to penetrate within the macro pathways between each yarn or micro pathways between each fiber due to the presence of masking to fill these voids.
(246) (2) Chemical Effect: For micro pathways throughout the textile, whether micro pathways refer to micro cracks within the masking layer, micro voids between the yarn bundles or micro voids between individual fibers, the chemical mechanism of the masking solution's repulsion effect or ability to repel away from the sealant causes the sealant not to fill the micro voids. The repelling mechanism occurs when the oleophobic sealant tries to come into contact or close proximity with the highly hydrophilic masking layer. This is proven using solution solubility theory and solubility parameters developed by Joel H. Hildebrand. SI Hildebrand values (∂[SI]) demonstrate the masking solution and sealant solubility parameters indicating the solvency behavior of their specific solvents when they come into contact with one another. As noted in the Handbook of Solubility Parameters, CRC Press, 1983, the solvents in the masking solution (water and glycerol) are on the hydrophilic end of the solubility parameter range, whereas the solvent of the sealant (Heptane) is on the opposite end of the solubility parameter range. The ∂[SI] of water is 48.0, ∂[SI] of glycerol is 36.2, and ∂[SI] n-Heptane is 15.3.
(247) Thus, the masking agents of the present invention hinder undesirable migration of the sealant through, physical (e.g., blocking) and repulsion mechanisms. Thus, it may be desirable to use a sealant(s) whose solvent(s) has a solubility parameter of less than about 20 ∂[SI], for example from about 10 ∂[SI] to about 20 ∂[SI] and a masking agent solution(s) whose solvent(s) has a solubility parameter of greater than about 30 ∂[SI], for example from about 30 ∂[SI] to about 50 ∂[SI].
(248) Conclusions
(249) The use of blue dye in the silicone dispersion provided an excellent visual assessment of silicone penetration into the fabric. Both samples coated without prior mask application demonstrated substantial ingress of blue silicone sealant through the fabric to the inner surface. All three masking agent formulations appeared to substantially prevent ingress of silicone to the inner surface.
(250) Silicone Sealing Tests for Commercial Vascular Grafts
(251) The following equipment and materials were used to test sealing commercial grafts according to the present invention.
(252) 8 mm crimped polyester fabric commercial graft
(253) 14 mm crimped polyester fabric commercial graft
(254) Polyvinylpyrrolidone (PVP) Powder
(255) NuSil MED-6606 RTV Silicone
(256) N-Heptane
(257) Royal Blue Pigment
(258) De-ionised water
(259) Magnetic Stirrer
(260) Coating Variable Ranges
(261) The following values were used for the testing of the inventive sealing techniques of the present invention. PVP concentration in de-ionised water was varied on a weight basis at 1%, 2%, 4%, 6%, 8%, 10%, 15%, 20%, 25%, and 30%. Glycerol and silicone dispersion concentration was tested at PVP concentrations of 4%, 8%, 15%, and 30%. Glycerol concentrations were used on PVP concentrations of 5%, 15%, and 30%. These concentrations were percentage of glycerol to PVP.
(262) The variations of PVP, glycerol, and silicone tested were as follows:
(263) TABLE-US-00010 TABLE 10 Glycerol Silicone Concentration Concentration PVP Concentration (%) (% of PVP) (%) Sample 1 2 4 6 8 10 15 20 25 30 5 15 30 15 30 1 X X 2 X X 3 X X *4 X X 5 X X 6 X X *7 X X 8 X X 9 X X *10 X X *11 X X X 12 X X X 13 X X X 14 X X X 15 X X X *16 X X X 17 X X X 18 X X X *19 X X X 20 X X X 21 X X X 22 X X X 23 X X X 24 X X X 25 X X X *26 X X X *Denotes samples to be applied to both types of grafts, i.e., First and Second graft samples.
(264) Sample Preparation
(265) Each sample was made from of a section of the commercial grafts. The grafts were first cut to length by first fully stretching the graft to remove the crimps, and then a section of 180 mm length was cut with a single edge razor blade. Each sample was weighed.
(266) Mask Preparation
(267) A measured amount of de-ionised water was placed into a 100 ml plastic beaker. A magnetic stirrer was placed into the de-ionised water. While stirring, PVP and glycerol (if any) were added. Stirring continued until there was no solute visible.
(268) Masking Agent Application
(269) The graft samples were coated by immersing the graft samples within the mask solution and agitating the graft by gloved hands, so the samples were fully coated inside and out.
(270) Once the grafts were fully coated, excess mask solution, if any, was removed. Next, each graft was attached to a mandrel by using cable ties. One end of the graft was secured to the mandrel by a cable tie, then the graft was extended to 60% of its overall extended length (108 mm), and the other end of the graft was secured to the mandrel by another cable tie. The mandrel was then placed horizontally on a rotating mount and allowed to air dry. Once dry, the masked grafts were weighed.
(271) Sealant Preparation
(272) The silicone dispersion was supplied as a 30% solid content. Additional amounts of n-Heptane were added to reduce that solid content to 22.5% then 15. A blue dye was added to the silicone dispersion.
(273) Sealant Application
(274) The mandrel with the graft mounted was be placed on the rotary motor to slowly spin the graft. The sealant was applied with a paint brush starting at one end and working to the other end. This was repeated until there was an excess of sealant dispersion on the graft. Once the targeted level of silicone was applied onto the graft, the graft was transferred to a rotating mount and allowed to air dry. Once dry, the sealed graft was weighed.
(275) Masking Agent Removal
(276) Once the grafts were fully dried, the masking agents were removed. This was done by washing the grafts in a washing machine on a 90° C. wash (with no detergent). This caused the PVP to dissolve in the water and thus be removed from the graft. The 90° C. temperature also aided in complete curing of the silicone. When the wash was complete, the grafts were hung up to air dry. After drying, the finished grafts were weighed.
(277) Silicone Adherence
(278) A good coating adhesion can also be demonstrated if the graft coating maintains its integrity in a high pressurised state. Pressure can be used as a measure over all sizes of grafts because most of the overall hoop stress is borne by the stiffer fabric material of the graft. Furthermore, most of the forces acting on the silicone coating for delaminating it happen in the gaps between bundles of fibres as the weave structure does not change for different diameters of graft, then this area and consequently the force acting on that area will be consistent. Therefore, irrespective of the size of graft the same pressure will produce the same force to delaminate the silicone coating.
(279) To ensure the position of the bundles within the fabric are as uniform as possible over all diameters, the fabric was crimp removed so the graft is in its fully extended shape. In accomplishing this, the pressure applied was above the pressure that it takes to fully extend the graft. Since this pressure will be different for each size of graft, the graft that needs the highest pressure to fully extend itself (i.e., the one of smallest diameter) will be used as a worst-case scenario. Once this worst-case pressure is determined, a factor of safety (FOS) is applied and it is this FOS corrected pressure that is used as a minimum requirement for all grafts. If the graft can be pressurised to this FOS corrected pressure with no visual signs of the coating delaminating (bubbles forming), then it can be deduced that the coating has sufficient and acceptable adhesion/integrity.
(280) One method of testing for delamination is as follows:
(281) Connect the graft to a pressure rig, ensuring one end is plugged;
(282) Slowly apply pressure to the graft;
(283) Stop at 120 mmHg (clinical pressure) and look for signs of delamination (bubbles);
(284) Measure the leak rate and record it in mm/cm.sup.2/min;
(285) Increase the pressure in increments up to the FOS corrected figure is reached;
(286) If any signs of delamination are visible at any point stop the test, mark as failed;
(287) Hold at the FOS corrected pressure for 1 min; and
(288) If no signs of delamination are present, mark graft as pass.
(289) The following pressure tests were conducted:
(290) The grafts were pressurised with water to observe if there were any signs of the silicone losing its bond from the graft. The pressure was to be increased slowly to a maximum pressure of 600 mmHg. The adherence was noted as follows:
(291) 0—Silicone is well adhered to graft and showing no signs of failure;
(292) 1—Graft reached the maximum pressure, but the leak rate has visibly increased;
(293) 2—Silicone coating has started to fail, showing jets of water coming from the graft; and
(294) 3—Silicone coating has failed, and a bubble has appeared on the surface.
(295) Penetration Depth
(296) The effectiveness of the mask was determined by how far the silicone wicked through the fabric. Desirably, the silicone will sit on the outside surface of the graft and not unduly penetrate the graft structure. If the masking agent was not effective, then the silicone was visible within the fabrics and on the inside edge. To visualise this, the grafts were cut lengthways and a cross section was examined under high magnification.
(297) The degree of penetration was noted as follows;
(298) 0—Silicone only visible on the outer surface of the graft;
(299) 1—Silicone is visible between fibres of the graft but only up to 50% of the thickness;
(300) 2—Silicone is visible penetrating to the inside surface; and
(301) 3—Silicone visible everywhere, the entire graft structure is blue.
(302) Test Results Summaries
(303) TABLE-US-00011 TABLE 11 WEIGHT SUMMARIES Weight of Graft Segment After After After Amount of Amount Ratio of Masking Sealant Washing Masking of Sealant to and and and Agent Sealant Masking Sample Drying Curing Drying Applied Applied Agent Name Initial (g) (g) (g) (g) (g) (g) (g/g) 1 0.703 0.714 1.496 1.485 0.011 0.782 71.1 2 0.714 0.739 1.484 1.46 0.025 0.745 29.8 3 0.741 0.779 1.436 1.392 0.038 0.657 17.3 4 0.673 0.721 1.239 1.182 0.048 0.518 10.8 A4 1.089 1.159 2.31 2.229 0.07 1.151 16.4 5 0.689 0.778 1.199 1.1 0.089 0.421 4.7 6 0.698 0.778 1.216 1.129 0.08 0.438 5.5 7 0.694 0.813 1.454 1.319 0.119 0.641 5.4 A7 1.026 1.198 2.047 1.86 0.172 0.849 4.9 8 0.695 0.864 1.492 1.31 0.169 0.628 3.7 9 0.688 0.939 1.541 1.276 0.251 0.602 2.4 10 0.663 0.969 1.537 1.207 0.306 0.568 1.9 11 0.739 0.778 1.382 1.339 0.039 0.604 15.5 A11.sup. 1.08 1.119 2.086 2.041 0.039 0.967 24.8 12 0.658 0.712 1.262 1.201 0.054 0.55 10.2 13 0.717 0.83 1.486 1.368 0.113 0.656 5.8 14 0.719 0.816 1.463 1.357 0.097 0.647 3.7 15 0.717 0.853 1.513 1.367 0.136 0.66 4.9 16 0.701 0.888 1.502 1.298 0.187 0.614 3.3 A16.sup. 0.896 1.103 1.731 1.503 0.207 0.628 3.0 17 0.738 1.067 1.879 1.531 0.329 0.812 2.5 18 0.719 1.183 1.881 1.395 0.464 0.698 1.5 19 0.705 0.754 1.502 1.446 0.049 0.748 15.3 A19.sup. 0.878 0.924 1.682 1.632 0.046 0.758 16.5 20 0.717 0.759 2.063 2.016 0.042 1.304 31.0 21 0.709 0.809 1.46 1.355 0.1 0.651 6.5 22 0.741 0.844 2.121 2.007 0.103 1.277 12.4 23 0.715 0.855 1.487 1.333 0.14 0.632 4.5 24 0.688 0.867 2.03 1.846 0.179 1.163 6.5 25 0.711 1.057 1.818 1.451 0.346 0.761 2.2 26 0.699 1.038 2.464 2.115 0.339 1.426 4.2 A26.sup. 1.356 2.058 4.448 3.689 0.702 2.39 3.4
(304) The ratio of sealant to masking agent on a gram to gram or weight dry basis varied from about 1:1 to about 70:1. Useful ratios also include ratios of sealant to masking agent from about 2:1 to about 20:1, including from about 2:1 to about 10:1, on a dry weight basis. These ratios, however are non-limiting. The weight ratio of silicone (or other sealant agents) to PVP (or other masking agents) may vary from about 0.1:1.0 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents) to about 100:1 wt. silicon (or other sealant agents)/wt. PVP (or other masking agents, desirably from about 1:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents to about 20:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents, more desirably from about 2:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents to about 10:1 wt. silicone (or other sealant agents)/wt. PVP (or other masking agents.
(305) TABLE-US-00012 TABLE 12 PENETRATION TEST RESULTS Glycerol Penetration Sample PVP as % of Grading Scale Number % PVP 0-3 Comment 1 1 0 3 2 2 0 3 3 4 0 2 4 6 0 2 A4 6 0 2 5 8 0 2 6 10 0 1 7 15 0 2 A7 15 0 2 8 20 0 2 9 25 0 0 Delaminated 10 30 0 0 Delaminated A10 30 0 Not Made 11 4 5 2 A11 4 5 2 12 4 30 2 13 8 5 2 14 8 30 2 15 15 5 1 16 15 30 0 A16 15 30 1 17 30 5 0 Delaminated 18 30 30 0 Delaminated 19 4 15 2 A19 4 15 2 20 4 15 2 21 8 15 2 22 8 15 1 23 15 15 1 24 15 15 1 25 30 15 0 Delaminated 26 30 15 0 Delaminated A26 30 15 0 Delaminated
(306) The results, which are tabulated in order of PVP masking agent concentrations, showed a clear correlation between higher levels of PVP and reduced penetration of the silicone sealant into the inner lumen of the graft samples.
(307) In general, PVP mask concentration of 10% or greater prevented the bulk penetration of silicone to more than 50% into the fabric thickness. In some samples, they were small “fingers” or “slivers” of silicone evident between the yarn bundles at the interstices created by warp and weft yarn bundles. Such interstitial silicone represented a very small percentage of the overall inner surface area of the fabric.
Adhesion Test Results
(308) TABLE-US-00013 TABLE 13 Measured Measured Leakage Leakage (ml/min) (ml/min) Adhesion Glycerol @120 @600 grading Sample PVP as % of mmHg mmHg Scale Number (g) PVP Result 1 Result 3 0-3 1 1 0 0 0 0 2 2 0 0 0 0 3 4 0 0 0 0 4 6 0 0 4 0 A4 6 0 33 3 5 8 0 19 1 6 10 0 40 1 7 15 0 4 14 0 A7 15 0 31 1 8 20 0 12 46 1 9 25 0 Delaminated 3 10 30 0 >500 3 A10 30 0 11 4 5 0 1 0 A11 4 5 0 5 0 12 4 30 0 0 0 13 8 5 9 86 2 14 8 30 1 22 1 15 15 5 3 22 1 16 15 30 1.5 1 A16 15 30 34 190 1 17 30 5 >1000 3 18 30 30 >1001 3 19 4 15 0 0 0 A19 4 15 4 27 0 20 4 15 0 0 0 21 8 15 0.5 5 0 22 8 15 0 3 23 15 15 1.5 11 0 24 15 15 0 3 25 30 15 Delaminated 3 26 30 15 Delaminated 3 A26 30 15 Delaminated 3
(309) The above results, which are tabulated in order of PVP masking agent concentrations, show a clear correlation between higher levels of PVP and reduced adhesion of the silicone sealant to the fabric. Two mechanisms by which silicone penetrated into the inner surface of the fabric were observed, i.e., either through the yarn bundle fibers or by passing between the gaps in the yarn bundles. The lower concentrations of mask agent (>4% PVP) appeared to inhibit the flow of polymer through the yarn fibers, however it was not in all cases sufficient to substantially prevent the ingress of small “fingers” or “slivers” of silicone polymer between the gaps in the bundles, i.e., interstitial spaces between proximately juxtaposed yarns within the textile pattern. It appeared that slightly larger concentrations of mask agent (>15%) was required to completely block the passage of silicone polymer through between the gaps in the fiber bundles.
(310) Assessment of Handling
(311) The handling characteristics of grafts are the result of a series of complex interactions between the fabric structure, the graft diameter, the crimp pitch and form, the thickness profile of the polymer sealant and the amount of penetration of the sealant into the yarn bundles.
(312) The below assessment parameters, although subjective, aim to consider all of the following: bend radius at kink formation, flexibility, hoop stiffness (ability to remain fully open) and stretching.
(313) A grading score (1-4) was be used to assess handling characteristics;
(314) 1—Graft judged more flexible than reference sample.
(315) 2—Graft judged comparable to reference sample.
(316) 3—Graft judged to be stiffer than reference sample but with useable characteristics.
(317) 4—Graft judged too stiff for comparable use.
(318) The reference sample was considered to have excellent overall handling and at least comparable to currently commercially available gelatin sealed grafts.
(319) Polymer Sealant Coverage
(320) The amount of polymer sealant coverage on each sample was reported in mg/cm.sup.2 and was calculated by dividing the overall mass of polymer applied to each individual graft by the surface area of the graft. Previous crimped prototypes have demonstrated both effective sealing and suitable handling characteristics with polymer coverages of at least about 8 mg/cm.sup.2 ranging up to about 14 mg/cm.sup.2. Coverage levels above 14 mg/cm.sup.2 increased the overall stiffness of the handling characteristics beyond that of a standard gelatin sealed graft, however increase stiffness and therefore increased amount of polymer coverage may be advantageous for some graft applications.
(321) Tensile Extension Force
(322) Samples were mounted between jaws of Lloyd Tensile Test machine with jaws spacing of 80 mm. The machine was zeroed and the jaws extended by 20% (16 mm) and the maximum measured force was recorded.
(323) The results recorded are tabulated below, ranked in order from low to high for force-to-extend by 20%.
(324) These results demonstrated a strong correlation between handling assessment and force-to-extend, with lower extension forces corresponding to improved handling characteristics.
(325) A review of the polymer coverage values indicated that coverage levels of up to 40 mg/cm.sup.2 might be considered in order to achieve comparable handling characteristics to the reference sample (grading 2), as indicated by graft sample #15.
(326) All grafts which demonstrated delamination of the polymer sealant during pressurized adhesion tests are by a note (1) highlighted in italics. This list indicates that poor adhesion can result in low Extension Forces and improved handling characteristics. This result supports the theory that acceptable handling characteristics rely on lower levels of penetration of sealant into the yarn bundles.
(327) TABLE-US-00014 TABLE 14 Handling Force to Extended Surface Polymer Assessment Extend Sample Dia, Length, Area, Coverage, Grading, by 20% No. mm mm cm.sup.2 mg/cm.sup.2 1 to 4 (N) 18 (1) 8 130 32.7 43 1 0.29986 10 (1) 8 125 31.4 38 1 0.37938 5 8 120 30.1 36 1 0.4067 25 (1) 8 130 32.7 44 1 0.41064 6 8 135 33.9 33 2 0.48247 16 8 130 32.7 40 2 0.48938 17 (1) 8 140 35.2 44 1 0.52805 8 8 130 32.7 40 2 0.53074 7 8 132 33.2 40 2 0.54057 9 (1) 8 125 31.4 41 1 0.57061 13 8 140 35.2 39 2 0.58817 4 8 125 31.4 38 2 0.60156 12 8 135 33.9 35 3 0.69369 15 8 135 33.9 40 2 0.71933 14 8 130 32.7 42 3 0.76625 3 8 135 33.9 41 3 0.78701 11 8 130 32.7 41 3 0.90773 1 8 135 33.9 44 3 1.0072 19 8 135 33.9 43 3 1.0302 23 8 140 35.2 38 3 1.0372 2 8 140 35.2 41 3 1.1116 21 8 125 31.4 43 3 1.1234 26 (1) 8 134 33.7 63 4 1.1571 22 8 125 31.4 64 4 1.8936 24 (1) 8 111 27.9 66 4 2.1711 20 8 115 28.9 70 4 3.0235 .sup. 64B 10 620 194.7 12.1 Reference Sample Note: (1) demonstrated delamination of the polymer sealant during pressurized adhesion tests
(328) Conclusions
(329) Acceptable handling characteristics were achieved with lower levels of penetration of sealant into the yarn bundles. The use of the masking agents to limit the amount of polymer penetration into textile fabric can be utilized for improved handling characteristics. Polymer coverage levels of up to 40 mg/cm.sup.2 were demonstrated to achieve comparable handling characteristics to the reference sample as assessed by surgeon users.
(330) Photographs of select samples from Tables 10-14 are reproduced in
(331)
(332)
(333)
(334)
(335)
(336)
(337)
(338)
(339) Glycerol Hydration of Masking Agents
(340) The use of glycerol within different masking agent formulations has been demonstrated on multiple formulations with the aim of hydrating or plasticizing the (PVP) masking agent and improving its ability to cover and fill the yarn structure and prevent the sealant dispersion from ingress to the inner surface.
(341) Masking Agent Sample Preparation
(342) Masking agents were prepared using following method:
(343) A target weight of PVP (MW 10,000) was introduced in a plastic beaker on a scale balance. A 100 ml masking agent solution was prepared at a target mass of 10 g PVP (10% concentration). The target volume of de-ionised water was introduced into a 100 ml plastic measuring cylinder. A target volume of 90 ml was required. The de-ionised water was added into the PVP in plastic beaker. A magnetic stirrer rod was placed in the water, and the beaker was placed on the magnetic stirrer. The magnetic stirrer was turned on at a speed of 350-450 RPM, the stirrer was centered in the beaker. The stirring was done at room temperature. Stirring continued until there was no visible PVP solute, but for at least 2 minutes. After stirring the masking agent solution, it can be removed from stirrer and used for control sample preparation.
(344) Additional steps were used for subsequent samples with added glycerol. The plastic beaker was returned to scale balance, tared, and the required quantity of glycerol was added to the masking agent solution. The target glycerol content was calculated as a percentage by mass of the PVP. The target weight of Glycerol added at each stage was 1 g, corresponding to cumulative weights of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 g. Each beaker was stirred for at least 2 minutes after each added quantity of Glycerol.
(345) A summary of the samples prepared are shown below.
(346) TABLE-US-00015 TABLE 15 Volume PVP PVP % Glycerol Glycerol Sample Ref. of water Weight w/v Weight as % of PVP Control 90 ml 10 g 10% 0 0 A) 10% Glycerol 90 ml 10 g 9.9% 1 g 10% B) 20% Glycerol 90 ml 10 g 9.8% 2 g 20% C) 30% Glycerol 90 ml 10 g 9.7% 3 g 30% D) 40% Glycerol 90 ml 10 g 9.6% 4 g 40% E) 50% Glycerol 90 ml 10 g 9.5% 5 g 50% F) 60% Glycerol 90 ml 10 g 9.4% 6 g 60% G) 70% Glycerol 90 ml 10 g 9.3% 7 g 70% H) 80% Glycerol 90 ml 10 g 9.3% 8 g 80% I) 90% Glycerol 90 ml 10 g 9.2% 9 g 90% J) 100% Glycerol 90 ml 10 g .sup. 9% 10 g 100%
(347) Dispersion Drop Castings
(348) Three individual drops of each masking agent formulation were cast onto a dark coloured sheet to allow visual observation during the drying process. The drying was accelerated by using a desk fan at room temperature
(349) Assessments of the masking agents after drying were as follows:
(350) TABLE-US-00016 TABLE 16 Assessment Assessment Sample Ref. after 12 hours after 96 hours Control Looked white, Dry, Brittle Dry to touch A) 10% Glycerol Looked hydrated, Looked hydrated, Dry to touch Dry to touch B) 20% Glycerol Hydrated, Soft, Hydrated, Soft, Tacky to touch Tacky to touch C) 30% Glycerol Very Sticky to Sticky to touch touch D) 40% Glycerol Sticky, still wet Sticky, still wet E) 50% Glycerol Wet to touch Wet to touch F) 60% Glycerol Wet to touch Wet to touch G) 70% Glycerol Wet to touch Wet to touch H) 80% Glycerol Wet to touch Wet to touch I) 90% Glycerol Wet to touch Wet to touch J) 100% Glycerol Wet to touch Wet to touch
(351) Conclusions
(352) The control masking agent formulation (e.g., PVP-only) dried out fully within a few hours and became brittle. Use of this PVP-only masking agent may result in a stiff graft structure once mask is applied and dried. The use of 10% glycerol helped to hydrate the PVP masking agent solution, and appeared dry after 12 hours. A masking agent solution consisting of 20% glycerol retains some hydration at 12 hours and is soft/deformable to touch. A range of between about 1% and about 30% glycerol to PVP, by weight, provides appropriate ranges for use with the present invention.
(353) Moreover, the present invention is not limited to vascular prostheses in conduit-type shapes. The methods, coatings, and masking agents of the present invention may suitably be used with other textile products, including medical and non-medical (e.g., non-implantable) textile products. Other medical products may include ventricular assist devices, artificial heart conduits, medical sheets, patches, meshes, and the like. Non-medical textiles may include, but are not limited to, clothing, geotextiles, transportation textiles, military and/or defense textiles, safety and/or protective textiles, sports and/or recreation textiles, and the like. Further, textile products are not limited to tubular conduits, but may be of any shape including, but not limited to for example, sheets and/or tapes (e.g., two-dimensional products), or even three-dimensional shaped products other than conduit-shaped products.
(354) Useful polymeric materials and/or for fibers for non-medical or non-implantable textiles may include, but are not limited to, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePFTE), polyolefins, polyesters, poly(ether amides), poly(ether esters), poly(ether urethanes), poly(ester urethanes), poly(ethylene-styrene/butylene-styrenes), and other block copolymers. Useful animal fibers for the non-medical or non-implantable textiles of the present invention may include, but are not limited to, wool, alpaca, angora, mohair, llama, cashmere, and silk. Useful natural fibers may include, but are not limited to, linen, cotton bamboo, hemp, corn, nettle, soy fiber, and the like.
(355) The masking agents and/or the sealants may be applied by brushing, spray-coating, dipping or immersing, and the like. The present invention, however is not limited to such techniques, and other techniques, such as chemical deposition, vapor deposition, chemical vapor deposition, physical vapor deposition, printing and the like, may suitably be used. These techniques are generally suitable for medical textiles. However, for large commercial scale textile production, including non-medical textiles, other techniques may also be used. For example, coating and/or masking materials for textile sheets or substrates may be applied by squeegee type coating, roller coating, knife coating, nip coating, dip coating, cast coating, chemical deposition, vapor deposition, and the like. Moreover, printing techniques, such as roller printing, stencil printing, screen printing, inkjet printing, lithographic printing, 3D printing, and the like may be used with the present invention for applying the masking agents and/or the sealing agents. Furthermore, mechanical devices may be employed to control the depth of penetration of the masking agent and/or sealing agent into the wall of the textile substrate of graft. For example, with a tubular graft an expandable balloon may be to control the depth of penetration of the masking agent into the graft wall.
(356) Selective Mask Agent Removal Techniques:
(357) If desired, masking agent may be selectively removed, either in total or partially, from portions and/or surfaces of textile material of the present invention. One technique for selectively removing the masking agent is through the use of a particulate solid flowing against a portion or a surface of the textile. The particulate solid may ablate the masking agent to remove it from the portion and/or surface of the textile. Such flow of a particular solid is typically performed with a flow media, such as air, but other flow media, including gasses, vapors, or liquids, may be used.
(358) Desirably, the particulate solid has physical properties that will not unduly harm or adversely affect the textile graft or substrate of the present invention. One useful particulate solid is sodium bicarbonate. Other useful particulate solids include, but are not limited to, sodium chloride, sugar, magnesium sulphate, potassium chloride, calcium carbonate (including calcite), and talc. Sodium bicarbonate has a Moh's hardness of about 2.5. Other materials having a Moh's hardness from about 1 to about 5 may be used, more desirably a Moh's hardness from about 3 to about 4 may be used.
(359) When the particulate solid is being used to remove the water soluble masking agent of the present invention, it may be desirable to use a water soluble particulate solid, such a sodium bicarbonate. Use of a water soluble particulate solid may be useful in the removal of the solid particulate from the textile after ablation, for example by washing or spraying with water and/or a solvent, either before or after the application of the sealing agent or sealant. Any suitable organic or inorganic solvent may be used to wash or spray the textile.
(360) The particulate solid may have any useful particle size. In general, the larger the particle size or the coarser the material may offer greater ablating potentials. Useful particle sizes may vary from an average particle size from about 10 microns to about 1,000 microns, including from about 50 microns to about 350 microns, in particular an average particle size from about 100 microns to about 300 microns. Average particle sizes from about 250 microns to about 300 microns have been used to ablate masking agents from textiles substrates of the present invention. Such average particle sizes may be on a weight basis or a volume basis depending upon the test method for measuring particle size.
(361) Preferably the particulate solid or ablating material should have a crystalline structure and geometry with a particle size of greater than about 10 microns. A wide variety of substances could be used to abrade the mask. Any granular material which is capable of being pressure blasted when entrained in a pressurised flow of gas may be used. The granular material may have a hardness which exceeds that of the masking agent. Preferably the blasting material should be water soluble and non toxic. Examples of particularly useful materials include, but are not limited to, sodium bicarbonate, sodium chloride, sugar, magnesium sulphate, potassium chloride, and combinations thereof.
(362) Force of the ablating materials striking a surface also effects the ablating of the masking agent. Higher ablating pressures offer greater masking agent removal potentials, but may present higher potentials for damage of the textile pattern or yarns within the textile patterns. Desirably, solid particulates for ablating the textile substrates of the present invention are sprayed at a pressure from about 10 pounds per square inch force (psig) (or about 70 kilopascal gauge or kPa gauge) to about 50 psig (or about 340 kPa gauge). Useful spraying pressures include from about 20 psig (or about 140 kPa gauge) to about 50 psig (or about 340 kPa gauge), more desirably from about 20 psig (or about 140 kPa gauge) to about 30 psig (or about 210 kPa gauge).
(363) High ablating pressures, such as substantially greater than 50 psig (or 340 kPa gauge) may create multiple fibre breakages on the outer surface of the textile graft. While it may not be desirable to overly weaken the textile graft, textile grafts are typically over-engineered and are much stronger than required, so some yarn surface damage may be tolerates. Indeed, such broken outer yarn filaments, if present, may create a texturized effect on the outer surface of the coated graft, which may improve, for example, the general handling of the graft and adhesion of the sealant coating.
(364) The present invention, however, is not limited to the use of solid particulate matter for ablating the masking agent from textile substrates, and other techniques may suitably be used. For example, a brush, such as a bristle brush, may be used to selectively remove masking agent.
(365) Details of selective masking agent removal are further described below in Table 17.
(366) TABLE-US-00017 TABLE 17 Abrading Rotating Bristle Technique Soda Blasting Static Brushing Brushing Methods Sodium bicarbonate A hand held, bristle A counter rotating (Ecostrip) with an brush (0.5 mm brush (0.4 mm bristle average particle size bristle diameter, 15 diameter, 30 mm of 285 microns was mm bristle length) bristle length) was sprayed at 20-50 was held static brushed alongside the psig (140-340 kPa against a rotating rotating graft. gauge) onto a graft. rotating graft. Graft (A) PET woven graft, (A) PET woven graft, (A) PET woven graft, Samples crimped, straight (10 crimped, straight (14 crimped, straight (14 mm ID) with 35% mm ID) with 20% mm ID) with 20% PVP + 15% Glycerol PVP + 15% Glycerol PVP + 15% Glycerol Mask Mask Mask (B) PET woven graft, crimped, straight (14 mm ID) with 20% PVP + 15% Glycerol Mask
(367) Conclusions
(368) Soda blasting (sodium bicarbonate) abrading methods for removing masking off the outer surface worked well, while leaving the inner masking agent surface intact. Soda blasting is compatible with complex textile or graft geometry, including being particularly suitable for use on a crimped graft. Some non-limiting parameters in soda or particulate blasting are grain particle size and blast pressure. The use of soda or particulate blasting to improve adhesion levels of the silicone to PET yarn has been demonstrated. A crimped graft using a 20% PVP mask may, under certain conditions show delamination, however, this graft had improved levels of silicone adhesion when ablated with sodium bicarbonate under the same conditions. Graft inner surfaces appeared fully intact after blast abrasion. The sealing agent or sealant, however, is not limited to the use of silicone, and other sealing agent or sealant formulations may include, but not limited to, silicone, room temperature vulcanizing silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, polycarbonate, and combinations thereof with or without solvent; and the masking agent, however, is not limited to the use of polyvinylpyrrolidone, and masking agent formulations may include, but not limited to, polyvinylpyrrolidone glycerol, methyl cellulose, poly(ethylene glycol), polyethylene oxide, poly(ethylene glycol) hydrogel, and combinations thereof with or without water or other solvent.
(369) Bristle brushing showed some disruption to the outer mask surface. Static bristle brush and rotating bristle brush abrading methods with rotating graft may have a disadvantage with respect to controlling the level of force applied to the graft. For crimped grafts, larger brush contact surfaces may tend to focus the brushing action at the graft peaks, leaving valleys with limited abrasion.
(370) Further details of the sodium bicarbonate abrasion tests are described below in Table 18.
(371) TABLE-US-00018 TABLE 18 PVP Mask Concentration Soda Blast 20% PVP + 50% PVP Broken Yarns Yarn Damage Pressure 15% (No Identified Ranking (psig) Glycerol Glycerol) (Yes/No) (0-3)* 20 X No 0 25 X No 0 30 X Yes 1 35 X Yes 1 40 X Yes 2 45 X Yes 2 50 X Yes 3 *Yarn Damage Ranking 0 - No broken yarns identified 1 - Localized single yarn breakages, 2 - Localized multiple yarn breakages 3 - Broken yarn filaments over majority of surface.
(372) The utility of abrading the outer surface layer of masking agent to control masking coverage on a graft's exterior has been demonstrated. Such abrading may be used in preparation for subsequent coating and to increase silicone adhesion to PET graft. Ablating and other removal techniques allow for heavier application of masking agents, thereby providing greater assurance levels that the inner surface of the graft is free, including substantially free and completely free, of any silicone ingress during the application thereof. Abrading methods tested included soda blasting, static brushing, and rotating bristle brushing, but other techniques may be used. The ablation techniques may be used with any suitable masking agent, such as polyvinylpyrrolidone glycerol, methyl cellulose, poly(ethylene glycol), polyethylene oxide, poly(ethylene glycol) hydrogel, and combinations thereof with or without water or other solvent, and with any suitable The sealing agent or sealant, such as silicone, room temperature vulcanizing silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, polycarbonate, and combinations thereof with or without solvent.
(373) Sealant or Silicone Application by Spraying Using Forced Air:
(374) Target silicone coverage on the PET woven grafts for these examples was 14 mg/cm.sup.2. The dispersion mass of silicone based on the target coverage was calculated and loaded into an application syringe. Each sample graft was sprayed using a one-way pass (right to left) method with approximately 45 second delay between each spray pass to allow initial flash-off of excess solvent from the sealant composition. For silicone spraying, spray pressure was 11 pounds per square inch (psig) (or about 76 kPa gauge), traverse speed was 20 mm per second, and rotation speed of graft was typically from about 100 revolutions-per-minute or RPM to about 150 RPM. Higher rotations speeds, for example 300 RPM, were also tested. The spray passes were repeated until sealant volume in the syringe was used or applied.
(375) PET Graft Sample Descriptions:
(376) Graft Samples:
(377) (A) Samples #111-119: Straight woven PET crimped graft (14 mm ID),
(378) (B) Samples #120-121: Valsalva PET graft (22×20 mm ID)
(379) Masking Agent Composition:
(380) Mask Formulation: 12% PVP with 15% Glycerol (as % of PVP) (Sample #114 dyed blue).
(381) The masking agent solution was applied via immersion dipping of above graft samples 111 to 120 with rigorous manual manipulation. Excess masking was removed via manual squeezing between fingers for the straight grafts and between a roller press for the Valsalva grafts.
(382) Sealant Agent Composition:
(383) MED6-6606 (NuSil) silicone dispersion in heptane, 15% solid content, was used. Samples Nos. 111 and 115 further contained blue dye.
(384) Spray Results:
(385) Results of applying an even silicone coating across the length of the graft using forced air spraying are described below in Table 19.
(386) TABLE-US-00019 TABLE 19 Position of Sample 6 5 4 3 2 1 Average SD #111 Length (mm) 71 68.5 67.5 68.5 68.5 57 Weight (g) 0.77 0.733 0.717 0.716 0.717 0.632 Weight/Length 10.85 10.70 10.62 10.45 10.47 11.09 10.70 0.22 (mg/mm) #112 Length (mm) 71.5 71.5 71.5 71.5 72.5 73 Weight (g) 0.784 0.772 0.77 0.777 0.779 0.775 Weight/Length 10.97 10.80 10.77 10.87 10.74 10.62 10.79 0.11 (mg/mm) #113 Length (mm) 73.7 71.5 70.7 72.7 71.5 72.5 Weight (g) 0.778 0.759 0.78 0.815 0.799 0.826 Weight/Length 10.56 10.62 11.03 11.21 11.17 11.39 11.00 0.31 (mg/mm) Note: SD is an abbreviation for standard deviation
(387) Silicone Coated PET Graft Leak Tests (ISO 7198—Whole Graft Leak Testing) are described below in Table 20.
(388) TABLE-US-00020 TABLE 20 Silicone Comments on Delami- Sample Coverage Permeability Leakage nation at # (mg/cm.sup.2) (ml/min/cm.sup.2) at 120 mmHg 600 mmHg # 111 10.3 0.00 Near water tight Yes # 112 10.5 0.04 Heavy Beading No from Peaks # 113 10.5 0.06 Heavy Beading No from Peaks # 114 10.9 0.02 Beading No # 116 14.2 0.01 Bubble Yes delamination at seams # 117 14.0 0.49 Heavy Beading No from Peaks # 118 14.2 0.02 Beading at Peaks Yes # 119 15.3 n/a Full n/a Delamination # 120 13.4 0.58 Heavy Beading n/a from Peaks & Delamination at Bulge # 121 12.1 0.34 Delamination n/a at Bulge
(389) Silicone coated sample #111 demonstrated no leakage at 120 mmHg, but had bubble delamination at the peaks of the crimps and along the graft seam at 250 mmHg. Silicone coated sample #112 demonstrated heavy beading from peaks at 120 mmHg and no delamination at 600 mmHg. Silicone coated sample #114 demonstrated beading from peaks at 120 mmHg and no delamination at 600 mmHg. Silicone coated sample #116 demonstrated bubble delamination along both graft seams at 120 mmHg and expanded bubble delamination along the seams at pressures >120 mmHg. Silicone coated sample #117 and #118 demonstrated heavy beading and leakage at the peaks of the crimps during leak testing at 120 mmHg. Silicone coated sample #119 demonstrated initial delamination at graft seams then quickly migrated to cover the full circumference of the graft during leak testing at 120 mmHg. Silicone coated Valsalva samples #120 and #121 demonstrated heavy beading and leakage at the peaks of the crimps during leak testing at 120 mmHg. Bubble delamination on the Valsalva graft occurred near the transition of the bulge and the crimped body of the graft.
(390) Observations and Conclusions:
(391) Spray coating methods using forced air provided a consistent and an even coverage of silicone deposition throughout the length of the woven PET crimped graft.
(392) For Samples #111-114, spray parameters had a 25% dispersion loss during the spraying process, where actual silicone coverage (10.5 mg/cm.sup.2) was less than targeted coverage (14 mg/cm.sup.2). This dispersion loss is believed to be due to the forced air flow from the fume hood. It may be beneficial to shield the graft and nozzle from the high extraction flow to reduce direct dispersion loss during spraying. This dispersion loss was accounted for during preparation of Samples #116-121. For Samples #116-121, actual silicone coverage was between 12.1 and 15.3 mg/cm.sup.2. These results show that the process has a reasonably good level of control and repeatability.
(393) Average water permeability of silicone sprayed grafts was 0.03 ml/min/cm.sup.2. All silicone coated graft samples demonstrated water beading from the crimped graft peaks during the leak testing at 120 mmHg. Under these test conditions, 12% masking agent concentration may be too high to permit full and reliable adhesion of the silicone to the graft without potential delamination.
(394) During pressure leak testing, the weakest attachment strength of silicone to the textile or fabric appeared consistently to be at the seams of the woven PET graft. Samples #111, 116, and 118 demonstrated a bubble delamination on opposing graft seams. These observations suggest that the masking coverage may be affected by the localized variation in the weave structure on the seams of the graft. While not being bound by any particular theory, it is proposed this is due to the locally tight weave structure of the graft seam which presumably retains a higher mask concentration and/or offers a less texturized surface for the silicone attachment.
(395) As used herein a seam may refer to a discontinuity or a controlled change in a textile pattern along a portion of a textile graft, such as for example an edge of a flat woven tubular graft. The seam may be caused by a change in yarn density. The change in yarn density may be influenced by adding or dropping yarn ends during weaving or the like. The change in yarn density may also be influenced by changing relative spacing of the yarns within the textile pattern.
(396) For the Valsalva samples #120 and 121, the predominant area for delamination was on the Valsalva bulge adjacent to the transition to the crimped body. Although only hypothesis and not being bound by such hypothesis, it is believed that the masking agent wiping process employed was less effective at removing excess masking agent from this localized area, as the non-crimped bulge passed through the rollers and transitioned to the crimped body. The process to remove excess masking may therefore, if desired, be modified to accommodate any transitions between graft structure, e.g. crimped to non-crimped or additional branches, etc. For example, selective application of masking agent may be used where such portions of the graft may have lower level of applied masking agent as compared to the other portions of the graft. Alternately, or in addition to, selective removal of excess agent may be applied, including selective removal at just desired portion of the graft.
(397) Thus, the spraying of the textiles of the present invention with the use of forced air has been demonstrated as an effective method of controllably adding sealant or sealing agent. Any suitable agent or sealant, such as, but not limited to, silicone, room temperature vulcanizing silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, polycarbonate, and combinations thereof with or without solvent may be used.
(398) Silicone Spraying Trials Using Ultrasonic Application Techniques:
(399) The spraying silicone using ultrasonic on the exterior surface of a woven PET graft was investigated. Woven PET straight grafts were spray coated using a target silicone coverage. The ability for the sprayer to apply an even silicone coating across the length of the graft using ultrasonic techniques was investigated. The silicone coated grafts were tested for leakage.
(400) Spray Equipment and Methods:
(401) Automatic spraying system that utilized ultrasonic nozzles to atomize solutions to spray coat various substrates was used. Three benchtop models of the system included: (1) 400 (400×400 mm stage), (2) prism 500 (500×500 mm stage), and (3) prism 800 (800×800 mm stage). Listed below were the variables for the spraying experiments. 1. Silicone MED6-6606 (NuSil) Percent Solids Concentration: a. Original Percent Solids: 30%. b. Diluted Percent Solids: 24% (4:1 MED6-6606: Additional Heptane). c. 2 mL of MED51-4900-7 COLOR MASTER BATCH FOR LIQUID SILICONE ELASTOMERS was added to approximately 90 mL of diluted solution. 2. Head Type—Frequency of ultrasonics: ILDS Ultrasonic head from Ultrasonic Systems, Inc., Haverhill, Mass., USA. 3. Flow Rate—Syringe pump driven: 2.1 mL/min. 4. Head speed: 7-21 mm/sec. 5. Head Height: 10-20 mm. 6. Air Direction Pressure: 10-15 psig (or about 70-105 kPa gauge). 7. PM: 500. 8. Stroke Length: 110 mm. 9. # of Passes: 4-16 (Dependent of flowrate, and amount needed to deposit). 10. Time (Dependent on number of passes and head speed).
(402) Methods:
(403) For samples 64, non-crimped PET grafts (about 14 mm ID) were cut into about 8 to 10 cm segments. Each segment was loaded onto the spindle mandrel and secured with tape. The recipes with parameters listed below in the test matrix were completed for each sample.
(404) For samples 45, crimped PET grafts (about 14 mm ID) were stretched out to 28 cm and cut into 4 equal parts, approximately 110 mm total when fully stretched. Each sample was placed on the spindle mandrel and coated with the below parameter listed in the test matrix above. Each sample was evaluated for its ability to seal according to ISO 7198: Whole graft permeability.
(405) Results:
(406) TABLE-US-00021 TABLE 21 PET Graft Sample Silicone Spray Coating Parameters Air # Sample Flow Head Head Dir Pass- Time Oven Number Rate Speed Height Press RPM es Top Temp 64-7A 2.1 21 20 10 500 12 0:01:07 RT 64-7B 2.1 21 20 10 500 12 0:01:07 RT 64-7C 2.1 21 20 10 500 8 0:00:45 RT 64-11A 2.1 21 20 10 500 8 0:00:45 RT 64-11B 2.1 21 10 10 500 8 0:00:45 RT 64-11-C 2.1 21 10 15 500 8 0:00:44 RT 64-12A 2.1 21 10 15 500 12 0:01:07 RT 64-12B 2.1 10.5 10 15 500 12 0:02:10 RT 64-12-C 2.1 10.5 10 15 500 6 0:01:05 RT 64-8A 2.1 21 20 10 500 8 0:00:45 55 64-8B 2.1 21 20 10 500 4 0:00:22 RT 64-8C 2.1 21 20 10 500 4 0:00:22 55 45-17A 2.1 21 20 10 500 12 0:01:07 RT 45-17B 2.1 21 20 10 500 8 0:00:44 RT 45-17C 2.1 21 20 10 500 16 0:01:29 RT 45-17D 2.1 21 10 10 500 12 0:01:07 RT 45-18A 2.1 21 10 10 500 8 0:00:45 RT 45-18B 2.1 21 10 10 500 16 0:01:29 RT 45-18C 2.1 21 20 10 500 4 0:00:22 RT 45-18D 2.1 14 20 10 500 8 0:01:05 RT 45-21A 2.1 7 20 10 500 4 0:01:04 RT 45-21B 2.1 10.5 20 10 500 12 0:02:10 RT 45-21C 2.1 21 20 10 500 8 0:00:45 RT 45-21D 2.1 21 20 10 500 16 0:01:29 RT 45-14 2.1 21 20 10 500 15 0:03:13 RT Note: “RT” is room temperature
(407) TABLE-US-00022 TABLE 22 Digital Measuring Microscope Cross- Sectional Penetration Depth Chart Si Thick- Pene- Pene- Coating ness - Fabric Fabric tration tration Graft Amount Surface Thick Depth Depth Number Target (μm) (μm) (μm) (%) 45-17C 10.8 mg/cm.sup.2 10 192 0 231 146 0 233 199 0 150 252 78 31% 45-18D 8 mg/cm.sup.2 45 95 0 0% 13 108 0 0% 65 130 0 0% 20 171.65 60.112 35% 24 164 62 38% 39 60 0 0% 13 169 69 41% 38 184 57 31% 37 73 0 0% 45-21B 16 mg/cm.sup.2 85 127.3 170 146 214.1 54.1 25% 190 38.7 20% 64-11A 5.4 mg/cm.sup.2 24 166 51.5 31% 0 194 101 52% 97.8 29 64-12B 16 mg/cm.sup.2 110 0 130 130 0 151 173 0 160 166 95 57% 125 131 0 64-12C 8 mg/cm.sup.2 63 220 0 42 164 0 91 60 0 10 226 0 29 189 75 40% 93 85 0 16 190 118 62% 91145 Unknown 23 123 45 37% sample 45 207 0 14 32 159 0 0 174 75 43% 28 96 0 65 109 0 11 96 0 18 182 63 35% Noanix Unknown No Coating Visible
(408) TABLE-US-00023 TABLE 23 Permeability and Delamination Testing (ISO 7198 - Whole Graft Leak Test) Pressure (psig) 2.4 Ran for 30 secs Coat Crimp/ Amount leaked Number (mg/cm{circumflex over ( )}2) Straight Leak? (mL) Delamination 45-18C 2.7 Crimp Yes 440 No 45-17B 5.4 Crimp Yes 256 No 45-21A 8 Crimp Yes ~15 No 45-17C 10.8 Crimp No 45-21B 16 Crimp No 64-8B 2.7 Straight Yes 467 No 64-11A 5.4 Straight Yes 470 No 64-12C 8 Straight No 0 No 64-12B 16 Straight No 0 No
(409) Observations and Conclusions:
(410) Spray coating using Ultrasonic and force air shaping with a spinning substrate on 14 mm inner diameter non-crimped and crimped woven PET grafts provided an even coverage when assessed visually, a 24% solids silicone content was used with Ultrasonic. No masking agent was used before silicone was applied.
(411) Using ultrasonic spraying methods, silicone coverage levels are directly correlated to speed of head, ultrasonic frequency, rotational speed of graft, height of spray nozzle away from substrate, and flow rate of dispersion.
(412) Leak testing demonstrated that silicone did not delaminate, however, grafts did see varying levels of permeability based on the amount and thickness of silicone applied. Blue dye aids in cross-sectional imaging and penetration depth. The depth varies depending on the large intestacies of the base fabric. PVP masking agent does affect penetration depth.
(413) Masking Agent Deposition Examples:
(414) Various Masking Agent compositions, application methods, drying methods and washing methods on PET graft material were explored. Testing included Polyvinylpyrrolidone (PVP) in water, PVP/Glycerol in water, and PVP in Glycerol as masking agents.
(415) Methods:
(416) Masking Solution a (PVP/Glycerol in Water) Preparation:
(417) PVP Masking solutions found in Table 1 and 2 were created. Each solution was made by mixing water and PVP in a small collection container, then adding glycerol, if any, and dye.
(418) TABLE-US-00024 TABLE 24 Solution Concentrations for Round 1 of Masking Agent Deposition Testing Mass (g) Total Solution Mass of Sample Mass Water Glycerol Mass (g) PVP Mass (g) No. (g) (g) 0% 10% 25% 40% 50% 5% 10% 25% 40% 50% 1 30 28.5 0.0 1.5 2 30 27.0 0.0 3.0 3 30 22.5 0.0 7.5 4 30 18.0 0.0 12.0 5 30 15.0 0.0 15.0 6 30 25.5 3.0 1.5 7 30 24.0 3.0 3.0 8 30 19.5 3.0 7.5 9 30 15.0 3.0 12.0 10 30 12.0 3.0 15.0 11 30 21.0 7.5 1.5 12 30 19.5 7.5 3.0 13 30 15.0 7.5 7.5 14 30 105 7.5 12.0 15 30 7.5 7.5 15.0 16 30 16.5 12.0 1.5 17 30 15.0 12.0 3.0 18 30 10.5 12.0 7.5 19 30 6.0 12.0 12.0 20 30 3.0 12.0 15.0 21 30 13.5 15.0 1.5 22 30 12.0 15.0 3.0 23 30 7.5 15.0 7.5 24 30 3.0 15.0 12.0 25 30 0.0 15.0 15.0
(419) TABLE-US-00025 TABLE 25 Application Methods for Round 1 of Masking Agent Deposition Testing Sample # (refer to Test Matrix) Application Method Sample No. 1A 1B 1C 1D 2 1 1 6 11 16 21 2 2 7 12 17 22 3 3 8 13 18 23 4 4 9 14 19 24 5 5 10 15 20 25 6 26 31 36 10 46 7 27 32 37 42 47 8 28 33 38 43 48 9 29 34 39 44 49 10 30 35 40 45 50 11 51 56 61 66 71 12 52 57 62 67 72 13 53 58 63 68 73 14 54 59 64 69 74 15 55 60 65 70 75 16 76 81 86 91 96 17 77 82 87 92 97 18 78 83 88 93 98 19 79 84 89 94 99 20 80 85 90 95 100 21 101 106 111 116 121 22 102 107 112 117 122 23 103 108 113 118 123 24 104 109 114 119 124 25 105 110 115 120 125
(420) TABLE-US-00026 TABLE 26 Solution Concentrations for Round 2 of Masking Agent Deposition Testing Mass (g) Total Solution Mass of Sample Mass Water Glycerol Mass (g) PVP Mass (g) No. (g) (g) 0% 2% 6% 8% 10% 15% 20% 1 20 18.0 0.0 2.0 2 20 17.0 0.0 3.0 3 20 16.0 0.0 4.0 4 20 17.6 0.4 2.0 5 20 16.6 0.4 3.0 6 20 15.6 0.4 4.0 7 20 16.8 1.2 2.0 8 20 15.8 1.2 3.0 9 20 14.8 1.2 4.0 10 20 16.4 1.6 2.0 11 20 15.4 1.6 3.0 12 20 14.4 1.6 4.0
(421) TABLE-US-00027 TABLE 27 Application Methods for Round 2 of Masking Agent Deposition Testing Sample # (refer to Test Matrix) Application Method Sample No. 1A 1B 1C 1D 2 1 1 2 3 4 5 2 6 7 8 9 10 3 11 12 13 14 15 4 16 17 18 19 20 5 21 22 23 24 25 6 26 27 28 29 30 7 31 32 33 34 35 8 36 37 38 39 40 9 41 42 43 44 45 10 46 47 48 49 50 11 51 52 53 54 55 12 56 57 58 59 60
(422) Masking Solution B (PVP in Glycerol) Preparation:
(423) Four PVP solutions for deposition were created: (1) 25% w/w PVP in water, (2) 50% w/w PVP in water, (3) 25% w/w PVP in glycerol and (4) 50% w/w PVP in glycerol. Each solution was made by mixing PVP with glycerol in a small collection container and heated for 10 minutes.
(424) Masking Application Methods:
(425) For each Masking solution A and B, the following five application methods were used to deposit the masking solution onto a petri dish or straight onto a PET sample. Application Method 1A: Coated the petri dish with 0.5 mL of solution and laid woven PET coupon sample on top of the spread solution. The sample was air dried. Application Method 1B: Coated the petri dish with 0.5 mL of solution and laid woven PET coupon sample on top of spread solution. Place deposition weight on top of the sample. The sample was air dried. Application Method 1C: Coated the petri dish with 4 mL of solution and allowed the solution to air dry on the bottom of the dish. Application Method 1D: Coated petri dish with 4 mL of solution and placed in 50° C. oven to dry. Checked sample after 30 minutes in the oven and made visual observations. If all water appears to have evaporated, sample was removed from oven and make observations described below. If water had not evaporated, continued to check samples every 15 minutes until samples were dry and can be removed from the oven. When removed, proceed with observations described below. Application Method 2: Placed the woven PET coupon sample in the petri dish and used transfer pipet to coat the sample with 0.5 mL of solution. Dropped the solution in an evenly distributed manner to the top face of the sample. The sample was air dried. Application Method 3: Immersion of woven PET crimped graft in the Mask solution.
(426) Masking Drying Techniques:
(427) Used heat during the drying process to assess the influence of the masking agent during the drying process. Investigated the influence of (1) ambient air flow with rotation after Mask application method 3, (2) heat using an oven after Mask application method 1D, (3) irradiated heat using heated internal mandrel after Mask application method 3, (4) forced hot air 33 mm away from the sample after Mask application method 3, and (5) hot air flow through the inner diameter of the PET graft sample after Mask application method 3.
(428) Masking agent drying techniques of forced hot air on exterior (A), heated internal mandrel (B), and hot air flow through the inner diameter of the PET graft sample.
(429) Masking Agent Observations:
(430) After deposition of Masking solution, the samples were allowed to dry. Round 1 samples were dried for 90 hours, and Round 2 samples were dried for 21 hours. After drying, results were documented based on the following parameters: 1. Visual Inspection: Noted any visual abnormalities in the deposition or dissemination of the solution on the test sample. Took photograph of each dried sample from the top and bottom of each dried sample to note the drying pattern and wicking penetration of each sample. 2. Brittleness/Stiffness: Manually manipulated each sample to test its brittleness. Rated the brittleness on a 0-5 scale where 0 is indistinguishable and 5 is glazed icing. Used 18 g blunt tip needle to puncture sample and make observations on whether the sample is sticky, tacky, or brittle. 3. Drying Time; Note the time allowed for the sample to dry and/or time points at which observations were made on the sample.
(431) Results:
(432) PVP/Glycerol in Water Mask:
(433) PVP concentration 10% and 15% produced the most “fabric like” samples. PVP concentration >25% were too hard and brittle without having glycerol present. Glycerol concentrations of 0% and 6% produced the most “fabric like” samples. Glycerol concentration >10% tended not to dry.
(434) Generally, an even material distribution and 100% penetration for method 1 (pipetting masking agent solution onto the woven PET coupon sample) and method 2 (placing the woven PET coupon sample on top of the masking agent solution) was obtained; therefore, no major differences between the two methods were observed. Added weight or force on a coupon sample laying on top of the masking agent solution created a drying pattern gradient, where less masking agent concentrated in the center of the PET sample (PET sample under the weight), and less or no masking agent present around the edges of PET sample, where there was no added weight.
(435) There was no major difference in visual inspection, brittleness, or drying time for PVP in water masking agent solutions deposited with heat when compared to samples of the same concentration with no heat.
(436) PVP in Glycerol Mask:
(437) Solutions of PVP in glycerol (no water) may be used as a masking agent.
(438) Concentrations of 50% w/w PVP fully dissolves in glycerol with heat and stirring. An even masking agent distribution and controlled wick of masking agent was observed for 25% w/w and 50% w/w PVP in glycerol solution. The PVP/glycerol masking agent solution tends to perform like a heavy syrup or molasses during wicking. The PVP/glycerol masking agent solution may have a viscosity from about 2,000 to about 100,000 centipoise at room temperature, more desirably a viscosity from about 50,000 to about 100,000 centipoise at room temperature. Viscosity ranges of from about 5,000 to about 100,000 centipoise at room temperature; from about 10,000 to about 100,000 centipoise at room temperature; from about 15,000 to about 100,000 centipoise at room temperature; from about 20,000 to about 100,000 centipoise at room temperature; from about 25,000 to about 100,000 centipoise at room temperature; from about 30,000 to about 100,000 centipoise at room temperature; from about 35,000 to about 100,000 centipoise at room temperature; from about 40,000 to about 100,000 centipoise at room temperature; from about 50,000 to about 100,000 centipoise at room temperature; from about 55,000 to about 100,000 centipoise at room temperature; from about 60,000 to about 100,000 centipoise at room temperature; from about 65,000 to about 100,000 centipoise at room temperature; from about 70,000 to about 100,000 centipoise at room temperature; from about 75,000 to about 100,000 centipoise at room temperature; from about 80,000 to about 100,000 centipoise at room temperature; from about 70,000 to about 90,000 centipoise at room temperature; are also useful. Masking agent solutions of 12% and 20% PVP in water had viscosities of less than about 20 centipoise at room temperature. Glycerol was tested to have a viscosity of about 210 centipoise at room temperature. A 50% PVP in glycerol has a viscosity of greater than 80,000 centipoise at room temperature. Surface tension (pendant drop method) was measured at about 70 mN/m for water, about 65 mN/m for glycerol, 64 mN/m for 20% PVP in water; and about 68 mN/m for 12% PVP in water. These tests were all done within about twenty minutes. The PVP in glycerol samples were so viscous that results could not be measured within the normal twenty minute time period. The use or application of the PVP/glycerol masking agent solution has the advantage of controlling or minimizing wicking of the agent solution through the textile fibers, thereby possibly minimizing or eliminating the need for selective removal of the PVP/glycerol masking agent solution from undesired portion of the textile graft.
(439) Mask Drying Techniques:
(440) TABLE-US-00028 TABLE 28 Fabric & Mask Weights For Drying Trials Sample No. #109 A #109 B #109 C #109 D #109 A2 #110 #114 Fabric PET PET PET PET PET PET PET Extended length (cm) 24.5 25 25 24.7 24.7 23.5 34.5 Surface Area (cmsq) 169 173 173 171 171 162 152 Mass fabric (mg) 2311 2370 2363 2292 2309 2320 2124 Drying Method Flow Flow Hot Air Heated Hot Hot Hot Cabinet Cabinet Dryer Mandrel Internal Internal Internal air air air Mass, Wet mask (mg) 5553 5729 5417 5501 5529 5110 Mass, Dry mask (mg) 2760 2817 2788 2706 2757 2720 2403 Mass Mask added (mg) 449 447 425 414 448 400 279 Mass Mask/Fabric SA 2.65 2.59 2.46 2.43 2.63 2.46 1.84 (mg/cmsq) % Wt gain 19.4% 18.9% 18.0% 18.1% 19.4% 17.2% 13.1% Mass (post washing) 2307 (mg)
(441) Masking agent coverage on woven PET crimped grafts varied based on masking agent drying techniques. Ambient air dried samples (#109 A and 109B) looked identical and had a uniform blue color. Hot air dried sample (#109C) appeared significantly darker blue than all other samples, although it had a paler ‘watermarked’ area adjacent to the hairdryer fan and was additionally slightly bowed, presumably due to the air force from the fan. Heated manual sample (#109D) was very uniformly colored in the region directly adjacent to the heated mandrel. The crimp had also extended out in length in this region. In the zone above the heated mandrel the color was not as uniform and more closely resembled samples #109 A & #109B. Also, in this zone, the crimps had not elongated in length, suggesting a differential in the drying sequence between the area directly heated and cooler area above.
(442) Heat via oven did not appear to improve or hinder masking drying quality or decrease time of drying on woven PET coupon samples. However, heat increased PVP dissolvability in water and glycerol. Temperature and time are considerations for PVP and glycerol combinations with and without added water. Increased temperatures and/or increased rates of temperature increases may effect the final masking formulation. If heated too fast or too high, milky solutions may appear. Further, care should be taken not to “burn” the glycerol. Moderate temperatures and slow temperature increases are preferred. Heating conditions, including temperature, time and rate, should be selected so as not to degrade the masking agent components to a point where the function of the components are adversely effected. Some degradation, however, for example discoloration, may be acceptable or even desirable. For masking agent drying, a lid or cover over the masking agent coated woven PET coupon sample increased drying time. Woven PET samples with masking agent are desirably but not necessarily open to ambient air during drying. The drying techniques are not limited to PVP or polyvinylpyrrolidone, and the drying techniques may be used on any suitable masking agent formulations, such as but not limited to, polyvinylpyrrolidone glycerol, methyl cellulose, poly(ethylene glycol), polyethylene oxide, poly(ethylene glycol) hydrogel, and combinations thereof with or without water or other solvent.
(443) Additional Observations of Mask on Woven PET crimped grafts were as follows: Ambient Dried Masking Agent With Rotation: Samples #109 A and #109B demonstrated exterior graft body a uniform color, seam appears slightly darker blue, and color of inner surface appears identical to outer surface. Hot Air Dried Mask on Exterior Surface of PET Graft: Sample #109C demonstrate exterior graft body a darker blue color compared to other samples and the color of inner surface appears a lighter blue compared to the outer surface. Heated Mandrel Drying of Masking Agent From Interior Surface of PET Graft: Sample #109D demonstrated a uniformed exterior graft body color with inner and outer surfaces showing uniform depth of color. Hot Air Flow Drying of Masking Agent Through Interior Surface of PET Graft: Sample #110 demonstrated a uniformed exterior color between the peaks and valleys of the crimped graft with a paler blue top surface compared to its bottom surface of the graft.
(444) Visual assessment results of the inner and outer surface of each graft sample after masking agent are described below.
(445) TABLE-US-00029 TABLE 29 Outer and Inner Unifor- Surface Overall mity Masking Different Unifor- between Agent Colour mity Peak/ Sample Drying Intensity of Mask Valley # Fabric Method Y/N Coverage of Crimp #109 A PET Ambient N Y N #109 B PET Ambient N Y N #109 C PET Hot Air Y Y N External #109 D PET Hot Mandrel N Y Y #109 A2 PET Hot Air Y Y N Internal #110 PET Hot Air Y N Y Internal #114 PET Hot Air Y Y N Internal
(446) These results indicated that hot airflow around the outer graft surface may promote conglomeration of the masking agent on the outer surface (#109 C) and hot airflow through the internal lumen may promote conglomeration of masking agent on the inner surface (#109 A2, #110, #114).
(447) There was notable overall uniformity on graft sample #109 A2 on both outside and inside surfaces, however this graft showed some variation between peaks and valleys of the crimps.
(448) Graft sample #110, however, demonstrated some variation between the top and bottom faces, yet both faces showed considerable uniformity between peaks and valleys of the crimps.
(449) For graft sample #109 A2 (A) and #110 (B) after masking agent drying, there were inconsistencies between the funnelling of heated air through the inside of grafts #109 A2, #110, #114 and this may have resulted in significant variation in the resultant airflow acting on the inner surface.
(450) Mask Washing Process:
(451) A blue water-soluble dye was added to the masking agent solution used for all samples in order to provide a visual indication of both location of masking agent and concentration of masking agent on the dried graft. Sample #109 A was applied with masking agent in an identical manner to #109 B and then subjected to a 90C ‘Cotton Wash’ to assess the viability of removal of the blue dye from the woven PET graft. It was unclear if the dye stained only the PVP Mask or if it can permanently stain the PET yarn and therefore dye cannot be fully removed during the wash cycle.
(452) The mass of the graft was measured at each stage with the graft mass, post-wash returning to 2307 mg vs 2311 mg pre-mask application. This indicated that all PVP mask had been removed by the wash process, however after washing and drying #109 A appeared to have a very pale blue color, as compared below alongside a fresh graft sample. The presence of this blue tone suggests that traces of blue dye can stain the PET graft permanently and is therefore may not be a good tool by itself for assessing or confirming the presence of PVP masking agent in the finished sealed graft post-washing.
(453) Observations and Conclusions:
(454) For PVP/Glycerol in water masks: Masking agent concentrations were most “fabric like” with PVP concentration <25% w/w (most preferred 10-15% w/w) and glycerol concentrations <10% w/w (most preferred 0-6% w/w). Glycerol concentrations >10% w/w did not completely dry. PVP concentrations >25% w/w (at low glycerol concentrations) seemed hard and brittle. Heat increased the ability for PVP to dissolve in water.
(455) For PVP in glycerol (no water) masks: PVP/glycerol may be used as a masking agent without any added water. Concentrations of 50% w/w PVP were fully dissolved in glycerol with heat and stirring. An even masking agent distribution during application and controlled wicking of making agent was observed while using 50% w/w PVP in glycerol. The PVP/glycerol masking agent solution tended to perform like molasses during wicking, whereas the PVP/glycerol/water masking agent solution tended to perform like water during wicking. Excess masking agent on the outside of the graft can be removed or washed off with water.
(456) PVP/Glycerol without added water may contain trace amounts of moisture from exposure, for example, from atmospheric conditions. As used herein PVP/Glycerol without added water may be substantially free of water, for example less than 0.5 weight percent water, more desirably less than 0.1 weight percent water, including less that 0.01 weight percent water. For PVP/Glycerol formulations with purposely added water, it is believed that the added water may wick to some degree through the fibers of the yarn. Having PVP/Glycerol without added water does not present such a wicking problem.
(457) Masking agent solutions of PEG in Water were also prepared. In particular, nine PEG solutions for deposition were created as follows: (1) 10% w/w PEG (MW 600) in water, (2) 25% w/w PEG (MW 600) in water, (3) 50% w/w PEG (MW 600) in water, (4) 10% w/w PEG (MW 4000) in water, (5) 25% w/w PEG (MW 4000) in water, (6) 50% w/w PEG (MW 4000) in water, (7) 10% w/w PEG (MW 8000) in water, (8) 25% w/w PEG (MW 8000) in water and (9) 50% w/w PEG (MW 8000) in water. Each solution was made by mixing PEG with water in a small collection container. The PEG masking samples tested at 10% w/w concentration did not dry completely. PEG (MW 600) masking samples remained liquid at all concentrations tested. PEG (MW 4000, MW 8000) masking samples were almost completely solid at 50%. PEG masking samples at 50% w/w concentration did not completely dissolve. PEG (MW 600, 4000, and 8000) dissolved into water <50% w/w concentration and demonstrated to be a good potential polymer for the masking agent. PEG MW 600 remained liquid (i.e. never fully dried) for all concentrations (10%, 25%, 50%), PEG MW 4000 and 8000 were essentially a solid at 50%. PEG at 50% concentration did not completely dissolve, but PEG masking agent solutions at 45% w/w or less will likely dissolve. All PEG masking solutions cracked after the drying process. PEG samples crack similar to “desert cracks” (large, protruded cracks), whereas PVP samples crack similar to “window glass cracks” (small, micro channel cracking). The use of a plasticizer, such as glycerol may eliminate or minimize the presence of cracks.
(458) Removing excess masking agent from the outside of the graft surface may be accomplished by subjecting the outside of the graft to a wash or mist of water or other wash solvent. The step of removing excess masking agent may include having the graft disposed over a mandrel, such as mandrel 20. As described herein, the mandrel 20 may offer a solid exterior surface for which may act as a barrier from water washing the masking agent from the interior portions of the graft. Alternatively, or in addition to, mandrel 20 may have holes or perforations through which a medium, such as air or nitrogen, may flow to act as a further barrier against water from washing the masking agent from the interior portion of the graft.
(459) Masking Agent Application Methods: No masking agent deposition differences between pipetting masking agent directly onto the graft and graft placed on top of masking agent solution. Added weight (a nickel) dispersed the wicking of the masking agent and created an obvious gradient in the masking agent drying pattern. More masking agent was present on the graft where weight was not applied. The masking agent mass applied per unit surface area for PET samples was relatively consistent which indicates that the immersion dipping process is reasonably consistent. An even masking agent distribution and 100% penetration for all application methods: (a) Graft material placed on top of masking agent solution for wicking, (b) pipet masking agent solution on top of the graft material and (c) immersion dipping of graft.
(460) Mask Drying Methods: Oven drying did not affect masking agent drying compared to ambient air. Covered drying at room temperature or using heat increases masking agent drying time. Warm airflow around the graft surface appeared to have a significant effect on the masking agent drying mechanism and can be used to influence the final location and conglomeration of masking agent. The application of hot airflow through the inside of the graft appeared to promote the conglomeration of masking agent on the inner surface which provides an attractive process feature in ensuring the inner graft surface is free of silicone dispersion whilst minimizing masking agent presence on the outer surface that could reduce Silicone to fabric adhesion levels. The horizontal rotation of the graft during the masking agent drying process remained a valuable process aid to provide a perfectly straight (co-axial) graft for subsequent spray coating process, otherwise the graft dries in a bow shape. The horizontal rotation during drying process may be included when considering methods to apply warm airflow.
(461) Mask Washing Process: Blue dye added to masking agent solution provides a useful indication of both the dried masking agent location and concentration/conglomeration, however the dye may stain the PET graft permanently and is therefore may not a good tool for assessing or confirming the presence of PVP Mask in the finished sealed graft post-washing.
(462) The PET graft edges and seam appeared to hold or absorb different amounts of Mask when compared to the main body of the graft due to the localized differences in weave structure and density.
(463) Additional Testing on Textile Grafts:
(464) Graft Tested: ATEX Technologies Polyester Vascular Graft; 14 mm Diameter, 28.5 crimps per inch (CPI)
(465) Equipment and Materials:
(466) I. 14 mm crimped polyester fabric (Atex Technologies)
(467) II. Hothouse (HH) Spray Rig
(468) III. Bespoke Mandrels
(469) IV. Polyvinylpyrrolidone (PVP) Powder
(470) V. NuSil MED-6606 RTV Silicone
(471) VI N-Heptane
(472) VII. Easy Composites Royal Blue Pigment
(473) VIII. De-ionized water
(474) IX. Magnetic Stirrer (VFT Asset ID:22)
(475) X. Plastic Beakers
(476) XI. Cable ties
(477) XII. Single edge Razor Blades
(478) XIII Scales (VFT Asset ID:84)
(479) Coating Variables:
(480) The formulation of the masking agent and sealant composition are variables for consideration in controlling the effectiveness of the coating for the graft. Other factors that have been identified as being important include, but not limited to, masking agent drying method. The drying method was not varied in the below examples, and all grafts were dried in ambient air whilst being rotated.
(481) In examples described earlier herein above, silicone was brushed on to ensure a large coverage was achieved, this was to ensure there was enough silicone on the graft to show penetration but also a good coverage to ensure delamination was demonstrated. There was also blue dye added to the silicone to help assess the penetration visually. The below examples were carried out on two sets of 26 samples. The first set had blue dye added to the silicone and the coverage was set at 14 mg/cm.sup.2, these samples were used to assess penetration. The second set had silicone with no dye and the coverage was set at 20 mg/cm.sup.2, these samples were used to test adhesion.
(482) In addition to the above-described 52 samples, there was also be two control grafts C1 and C2. These were coated with silicone only with no mask application, C1 had the blue dye added to the silicone also.
(483) Coating Variable Ranges:
(484) The following values were used for the testing: PVP Concentration in DI water: 1%, 2%, 4%, 6%, 8%, 10%, 12% 15%, 17%, and 20%. Silicone dispersion concentration: 15% and 30% Glycerol Concentrations used on each PVP concentrations: 5%, 10%, and 15%. These concentrations are percentage of Glycerol to PVP concentration.
(485) The various samples prepared are shown in Table 30 below with target masking agent and sealant components as listed below.
(486) TABLE-US-00030 TABLE 30 Test Matrix HH Glycerol Silicone Sample ID Sample ID Conc. Conc. Blue No Blue No PVP Concentration (%) (% of PVP) (%) Dye Dye Dye Dye 1 2 4 6 8 10 12 15 17 20 5 10 15 15 30 C1 C2 136A 136B X 1 27 137A 137B X X 2 28 138A 138B X X 3 29 139A 139B X X 4 30 142A 142B X X 5 31 141A 141B X X 6 32 140A 140B X X 7 33 143A 143B X X 8 34 144A 144B X X 9 35 145A 145B X X 10 36 146A 146B X X 11 37 147A 147B X X X 12 38 148A 148B X X X 13 39 149A 149B X X X 14 40 150A 150B X X X 15 41 151A 151B X X X 16 42 152A 152B X X X 17 43 153A 153B X X X 18 44 154A 154B X X X 19 45 155A 155B X X X 20 46 156A 156B X X X 21 47 157A 157B X X X 22 48 158A 158B X X X 23 49 159A 159B X X X 24 50 160A 160B X X X 25 51 161A 161B X X X 26 52 162A 162B X X X Note: Samples C1 and 1-26 had a coverage of about 14 mg/cm.sup.2. Samples C2 and 27-52 had a coverage of about 20 mg/cm.sup.2.
(487) Preparation Method:
(488) Sample Preparation:
(489) Each sample was removed from the store and assigned a HH sample ID number. Each sample was to be made up of a section of graft. Firstly, the graft was cut to length. The graft was fully stretched removing the crimp, and a section of 225 mm length was cut with a single edge razor blade, once cut the end was cauterized to prevent fraying. The sample was clean and free of any debris, if it is not then it is to be discarded or washed and allowed to dry. Weighed the cut graft and noted the weight on the test sheet. Marked each sample with the HH sample ID number using black ink.
(490) Masking Agent Preparation:
(491) To prepare the masking agent formulation, the quantities of the components needed were calculated. This was done by calculating the percentage of each based on the test matrix. The amount of each component was noted on the test sheet for each sample. The following steps were followed to make the masking agent formulation. Placed the correct amount of de-ionized water into a 100 ml plastic beaker. Placed magnetic stirrer in the water and place the beaker on the magnetic stirrer. Turned the magnetic stirrer on at a speed of approximately 400 RPM at room temperature. Measured the correct weight of PVP and glycerol onto weighing boats. Added the PVP and Glycerol to the water. Stirred till there is no solute visible.
(492) Masking Agent Application:
(493) After the mask was fully prepared, the graft was coated. This was done by immersing the graft within the masking agent solution and agitating the graft by gloved hands, so it was fully coated inside and out.
(494) Once the graft was saturated, the excess masking agent solution was removed by running the graft between a thumb and index finger. Next the graft was attached to a mandrel, this was done using cable ties. Cable tied one end of the graft to the mandrel, extended the graft to 60% of its overall extended length (135 mm), and cable tied the other end of the graft to the mandrel. The mandrel was then be placed horizontally on the rotisserie and allowed to air dry for 12 hours. Once dry, weighed the masked graft and noted the weight on the test sheet.
(495) Sealant Preparation:
(496) The sealant came supplied as a 30% solid content. For the samples requiring the 30% the sealant was used straight from the container. For the remainder of the samples the sealant was diluted. The correct amount of n-Heptane was added to reduce that solid content to 15%.
(497) To allow for visualization of where the sealant is on grafts C1 and 1-26, blue dye was added to the silicone dispersion. The blue dye was to be added so that it amounted to 5% concentration with the solid content, i.e. at 15% solid content 15 g of dispersion has 2.25 g of solid content therefore you would add 0.11 g of dye.
(498) The appropriate amount of silicone was measured out to give the target coverage of either 14 mg/cm.sup.2 or 20 mg/cm.sup.2 coverage, and it was loaded into one of the disposable syringe barrels. This amount accounted for a 25% loss when spraying, therefore the actual target spray levels were 17.5 mg/cm.sup.2 and 25 mg/cm.sup.2 respectively.
(499) Sealant Application:
(500) The spray head was flushed with n-Heptane to ensure correct flow. The mandrel with the graft was then mounted in the spray rig. The spray rig was set up to spray the entire length of graft. The syringe barrel with silicone was mounted onto the spray head. The graft was rotated at 150 RPM, and the rate of traverse was set to 20 mm/s. The spray head was started and traversed over the entire length of the graft, once it reached the opposite end the spray head was stopped and allowed to return to the start of the graft. The solvent was allowed to flash off before making another pass, the time taken for the solvent to flash off increased with the amount applied. After the first pass a time of 10 seconds was waited, after each additional pass another 10 seconds was added to the wait time up to a maximum of 40 seconds between each pass. This continued till there was no dispersion left in the syringe barrel or there was an insufficient amount to make another full pass. Once the graft was removed from the spray rig the spray head was flushed with n-Heptane again.
(501) After application the graft was transferred to the rotisserie for a period of 12 hours then transferred to a stationary mount and allowed to air dry for a further 60 hours. Once dry, the sealed graft was weighed and the weight recorded.
(502) Masking Agent Removal:
(503) Once the graft was fully dried the mask was removed. This was done by washing the grafts in a washing machine on a “cotton cycle” at 90° C. (with no detergent). This caused the PVP to be dissolved in the water and removed, and also the high temperatures aided the curing of the silicone. When the wash was complete, the graft was hung up to air dry. Once the masking agent was removed and the graft was dry, the finished graft weight was recorded.
(504) Testing Method:
(505) Silicone Adherence:
(506) Silicone adherence may be difficult to measure in that the force to peel the silicone and the force to break the very thin silicone are both extremely low. Therefore, one method to demonstrate if the graft has good adherence is to pressurize the sample and see if there are any signs of the silicone losing its bond from the graft. The pressure was to be increased slowly to a maximum pressure of 600 mmHg. The adherence was to be noted as follows:
(507) 0—Silicone is well adhered to graft and showing no signs of failure.
(508) 1—Graft reached the maximum pressure, but the leak rate has visibly increased.
(509) 2—Silicone coating has started to fail, showing jets of water coming from the graft.
(510) 3—Silicone coating has failed, and a bubble has appeared on the surface.
(511) The adherence test was to be completed for all samples.
(512) Penetration Depth:
(513) The effectiveness of the masking agent was determined by how far the silicone wicked through the fabric. Ideally the silicone will sit on the outside surface of the graft and not penetrate the graft structure. If the masking agent was not effective, then the silicone may be visible within the fabric and on the inside edge. To visualize this, each graft was cut lengthways so that a cross section could be examined under high magnification. Particular attention was given to where this cut was made as the penetration may vary between the main body of the graft and at the seams. For comparative purposes a cross section was made at each position and the penetration noted at each.
(514) As the depth cannot be measured the penetration was noted as follows:
(515) 0—Silicone only visible on the outer surface of the graft.
(516) 1—Silicone is visible between fibers of the graft but only up to 50% of the thickness.
(517) 2—Silicone is visible penetrating to the inside surface.
(518) 3—Silicone visible everywhere, the entire graft structure is blue.
(519) The penetration depth test was completed for grafts C1 and 1-26 only.
(520) Results & Analysis:
(521) Table 31 below lists the measured weights of the masking agent and sealant formulations after the noted processing steps. Masking agent and sealant coverages are noted in the table.
(522) TABLE-US-00031 TABLE 31 Weight Summary After After After Sealant and Washing Mask Sealant Sample Initial Masking and Curing and Drying Coverage Coverage No. HH ID (mg) Drying (mg) (mg) (mg) (mg/cm.sup.2) (mg/cm.sup.2) C1 136A 1459 1459 3045 3041 0.000 15.2 1 137A 1440 1451 2927 2918 0.107 14.4 2 138A 1469 1495 2867 2839 0.246 13.0 3 139A 1475 1532 2815 2756 0.540 12.1 4 142A 1440 1590 3071 2915 1.439 14.2 5 141A 1187 1307 2584 2468 1.428 15.2 6 140A 1487 1578 3085 2993 0.855 14.1 7 143A 1575 1799 3214 2995 2.005 12.7 8 144A 1564 1867 3279 2973 2.681 12.5 9 145A 1534 1862 3161 2835 3.044 12.1 10 146A 1318 1645 3000 2677 3.474 14.4 11 147A 1619 1690 3139 3074 0.621 12.7 12 148A 1485 1557 2911 2841 0.679 12.8 13 149A 1311 1422 2605 2493 1.190 12.7 14 150A 1580 1723 3043 2899 1.270 11.7 15 151A 1588 1810 2870 2650 1.979 9.5 16 152A 1561 1805 3078 2834 2.219 11.6 17 153A 1510 1901 3011 2625 3.599 10.3 18 154A 1558 2029 3205 2745 4.216 10.6 19 155A 1374 1426 2405 2350 0.537 10.1 20 156A 1342 1395 2948 2901 0.560 16.5 21 157A 1333 1452 2706 2589 1.247 13.2 22 158A 1393 1503 2962 2852 1.107 14.7 23 159A 1390 1600 2844 2633 2.132 12.6 24 160A 1344 1525 3023 2842 1.905 15.8 25 161A 1398 1776 3273 2904 3.737 14.9 26 162A 1344 1722 3231 2857 3.979 15.9 C2 136B 1520 1520 3860 3857 0.000 21.6 27 137B 1432 1444 3474 3470 0.117 19.8 28 138B 1396 1428 3460 3439 0.321 20.5 29 139B 1493 1556 3625 3573 0.602 19.9 30 142B 1430 1582 3846 3711 1.509 22.6 31 141B 1428 1543 3695 3604 1.147 21.7 32 140B 1468 1570 3758 3571 1.004 20.7 33 143B 1533 1723 3758 3571 1.714 18.4 34 144B 1539 1868 4044 3720 2.992 19.8 35 145B 1523 1818 4034 3742 2.749 20.7 36 146B 1350 1704 3743 3393 3.709 21.4 37 147B 1459 1519 3649 3595 0.581 20.7 38 148B 1578 1636 3618 3547 0.517 17.6 39 149B 1266 1366 3074 2966 1.109 18.9 40 150B 1495 1638 3172 3030 1.344 14.4 41 151B 1556 1806 3289 3040 2.265 13.4 42 152B 1482 1700 3108 2890 2.065 13.3 43 153B 1560 2014 3509 3068 4.096 13.6 44 154B 1578 2132 4480 3944 4.979 21.3 45 155B 1263 1316 3473 3427 0.594 24.2 46 156B 1321 1375 3489 3434 0.571 22.3 47 157B 1324 1454 3681 3551 1.368 23.4 48 158B 1286 1407 3524 3407 1.316 23.1 49 159B 1287 1487 3644 3447 2.155 23.3 50 160B 1294 1488 3508 3317 2.052 21.4 51 161B 1270 1675 3802 3409 4.470 23.6 52 162B 1305 1684 3781 3406 4.065 22.5
(523) The above-described penetration grading of the sealant is listed in Table 32 below.
(524) TABLE-US-00032 TABLE 32 Penetration Glycerol Polymer Pene- Sample HH PVP as % of Concentration tration No. ID (g) PVP (%) Grading C1 136A 0 0 15 3 1 137A 1 0 15 3 2 138A 2 0 15 3 3 139A 4 0 15 3 4 142A 6 0 15 3 5 141A 8 0 15 3 6 140A 10 0 15 3 7 143A 12 0 15 3 8 144A 15 0 15 3 9 145A 17 0 15 3 10 146A 20 0 15 2 11 147A 4 5 15 3 12 148A 4 15 15 2 13 149A 8 5 15 3 14 150A 8 15 15 3 15 151A 12 5 15 2 16 152A 12 15 15 2 17 153A 20 5 15 2 18 154A 20 15 15 2 19 155A 4 10 15 2 20 156A 4 10 30 2 21 157A 8 10 15 2 22 158A 8 10 30 2 23 159A 12 10 15 1 24 160A 12 10 30 2 25 161A 20 10 15 2 26 162A 20 10 30 1
(525) Permeability data at 120 mmHg and leakage data are 600 mmHg are shown below in Table 33.
(526) TABLE-US-00033 TABLE 33 Adhesion Measured Measured Glycerol Leakage Leakage Permeability at Adhesion Sample as % of (ml/min) @ (ml/min) @ 120 mmHg Grading No. HH ID PVP (g) PVP 120 mmHg 600 mmHg (ml/min/cm.sup.2) Scale 0-3 C1 136A 0 0 1 137A 1 0 2 138A 2 0 3 139A 4 0 4 140A 6 0 5 141A 8 0 6 142A 10 0 7 143A 12 0 0 4.8 0 1 8 144A 15 0 2.8 27 0.05 1 9 145A 17 0 2.8 21 0.05 1 10 146A 20 0 7 43 0.14 1 11 147A 4 5 0 0 0 0 12 148A 4 15 0 0 0 0 13 149A 8 5 0 0 0 0 14 150A 8 15 0 4.6 0 1 15 151A 12 5 0 8.8 0 1 16 152A 12 15 2.5 16 0.05 1 17 153A 20 5 15 100 0.32 2 18 154A 20 15 Delaminated Delaminated 0 3 circumferentially circumferentially 19 155A 4 10 0 0 0 0 20 156A 4 10 0 0 0 0 21 157A 8 10 0 Delaminated 0 3 at the seam 22 158A 8 10 0 Delaminated 0 3 at the seam 23 159A 12 10 0 Delaminated 0 at the seam 24 160A 12 10 0 Delaminated 0 3 at the seam 25 161A 20 10 Delaminated Delaminated 0 3 26 162A 20 10 Delaminated Delaminated 0 3 C2 136B 0 0 0 0 0 0 27 137B 1 0 0 0 0 0 28 138B 2 0 0 0 0 0 29 139B 4 0 0 0 0 0 30 142B 6 0 0 0 0 0 31 141B 8 0 0 Delaminated 0 3 at the seam 32 140B 10 0 0 Delaminated 0 3 at the seam 33 143B 12 0 0 Delaminated 0 3 at the seam 34 144B 15 0 Delaminated Delaminated 0 3 circumferentially circumferentially 35 145B 17 0 0 Delaminated 3 circumferentially 36 146B 20 0 Delaminated Delaminated 0 3 circumferentially circumferentially 37 147B 4 5 0 0 0 0 38 148B 4 15 0.5 5.2 0.01 1 39 149B 8 5 0 0 0 0 40 150B 8 15 0 0 0 0 41 151B 12 5 0 Delaminated 0 3 42 152B 12 15 0 Delaminated 0 3 at the seam 43 153B 20 5 Delaminated Delaminated 0 3 circumferentially 44 154B 20 15 Delaminated Delaminated 0 3 45 155B 4 10 0 0 0 0 46 156B 4 10 0 0 0 0 47 157B 8 10 0 0 0 0 48 158B 8 10 0 0 0 0 49 159B 12 10 0 Delaminated 0 3 at the seam 50 160B 12 10 0 Delaminated 0 3 at the seam 51 161B 20 10 Delaminated Delaminated 0 3 52 162B 20 10 Delaminated Delaminated 0 3
(527) Glycerol Concentration:
(528) All samples in the above tables were considered for penetration and adhesion respectively, for each glycerol concentration and averaged. The addition of glycerol generally appeared to decrease penetration on 4-12% PVP, but had little effect in higher concentrations of 20%. With respect to adhesion the addition of glycerol appeared to have less effect at lower concentrations of PVP and tended to decrease adhesion at higher PVP concentrations.
(529) Silicone Dispersion Concentration:
(530) Looking at silicone concentrations showed no real significant difference between 15% or 30%. The penetration grading was so close when grading that they could be assumed to be the same for each PVP concentration. Therefore, there was no real difference in either case. One notable difference when spraying was that, the 30% silicone dispersion required much less time between coats and required less dispersion to be put on the graft, therefore the total time to coat these grafts was reduced.
(531) Table 34 lists forces-to-extend values for the various samples tested.
(532) TABLE-US-00034 TABLE 34 Handling PVP Force to Extend HH Mask Glycerol Polymer Silicone (Normalized with Sample Conc. Conc. Conc. Coverage Circumference) ID (%) (% of PVP) (%) (mg/cm.sup.2) (N/mm) 136(A) 0 0 15 15.24111 0.052 137(A) 1 0 15 14.4225 0.046 138(A) 2 0 15 12.97871 0.041 139(A) 4 0 15 12.13556 0.029 140(A) 10 0 15 14.1503 0.025 141(A) 8 0 15 15.24888 0.031 142(A) 6 0 15 14.14919 0.035 143(A) 12 0 15 12.71091 0.024 144(A) 15 0 15 12.46522 0.019 145(A) 17 0 15 12.0735 0.020 146(A) 20 0 15 14.43869 0.023 147(A) 4 5 15 12.72365 0.038 148(A) 4 15 15 12.79277 0.037 149(A) 8 5 15 12.67663 0.029 150(A) 8 15 15 11.71459 0.026 151(A) 12 5 15 9.46905 0.019 152(A) 12 15 15 11.57739 0.023 153(A) 20 5 15 10.26361 0.015 154(A) 20 15 15 10.62525 0.014 155(A) 4 10 15 10.0867 0.029 156(A) 4 10 30 16.48655 0.032 157(A) 8 10 15 13.15988 0.029 158(A) 8 10 30 14.67807 0.027 159(A) 12 10 15 12.61668 0.020 160(A) 12 10 30 15.76813 0.023 161(A) 20 10 15 14.88741 0.020 162(A) 20 10 30 15.92602 0.020
(533) Handling was assessed using the same procedure as described herein above. The above table shows average force values against PVP concentrations. PVP concentrations of above 10% gave better handling than the reference sample describe earlier herein. This supports the conclusions that the higher PVP concentrations lower penetration into yarn bundles which results in more favorable handling characteristics.
(534) Also, to be noted from the results was that although generally a higher silicone coverage resulted in poorer handling, it was not the only factor. For example, sample 162(A) had a high coverage of 15.9 mg/cm.sup.2, but had a better handling result than the reference sample. Alternatively, sample 147(A) had a lower coverage of 12.7 mg/cm.sup.2 and had worse handling than the reference sample. This suggests that it is in fact penetration that more greatly impacts handling rather than coverage as sample 162(A) had a penetration score of 1 compared to sample 147(A) that had a penetration score of 3. The increase in silicone coverage may have a smaller impact on handling than the change in PVP concentrations.
(535) Seam Delamination:
(536) During the adhesion testing, seam delamination was observed at higher pressures. The bubbles formed were diametrically opposed, running along the seam. The fabric was examined under microscope and the seam region was visibly more tightly weaved compared to the main body of the graft. Therefore, it was only logical to ask if the delamination at the seam is solely due to the protocol followed and should be considered a “fail”, or the tight seam hinders the silicone to adhere.
(537) In the initial analysis, any type of delamination was given an adhesion grade 3. However, after consideration, it was decided to examine the data again. The delamination at the seam was, this time, not considered a grade 3. So, this section will compare two cases: (1) seam delamination is considered as a fail criterion, (2) seam delamination is not considered as a fail criterion.
(538) Seam delamination was observed in the 8-12% range. An improvement of adhesion is evident in case 2, which only reinforces previous conclusions that the seam can have a negative effect on silicone adhesion. Similarly, a comparison between silicone content and adhesion in the two cases in question shows there is increased adhesion in case 2, specifically for 30% silicone. In case 1, 15% silicone content yields more favorable results, while in case 2, this is true for 30% silicone content.
(539) Conclusions:
(540) A consistent silicone coverage was achieved with a spray rig with a small standard deviation of the spraying results. The use of blue dyed silicone for penetration assessment and clear for adhesion assessment appeared to work very well. A repeatable mask coverage is achievable with standard deviation at 10% of the average value. The fabric has a large impact on the success of the coating, in particular the presence of a seam. Adhesion results of seamed grafts were not as comparable to seamless grafts, but if the grafts had not delaminated at the seams, the results would have been much closer. Both glycerol concentration and silicone dispersion concentration appeared to have less effect than previous, this may be a result of the points above. Glycerol appears to lower penetration at low PVP concentrations and has less effect at higher PVP concentrations. Glycerol has less effect on adhesion at lower PVP concentrations and at higher PVP concentrations lowers adhesion. Silicone dispersion had no clear influence on the success of the coating with respect to adhesion and penetration. Grafts coated with the 30% dispersion appeared to have a more uniform coating of silicone. Coating time was greatly reduced when using 30% dispersion compared to 15%. The reduced coating time with 30% dispersion lead to less blockages within the spray head. Handling was more sensitive to penetration rather than silicone coverage.
(541) The use of glycerol is, however, not limited to just as an additive to the masking agent formulation. Glycerol may be applied to the graft, in particular, to select portions of the graft, prior to the application of the masking agent. Such added glycerol may act as a plasticizer to the masking agent applied at the portion of the graft having the added glycerol. Portions of grafts that have, for example, different densities, such as but not limited to seams, may benefit with the application of glycerol prior to the application of the masking agent.
(542) Handling comparable to reference sample 64B was achievable with PVP concentrations greater than 10%. Handling is also effected by the uniformity of the silicone coating from peaks to valleys. Excluding seam delamination from the fail criteria, yields more positive results for a range of concentrations that were previously thought to be favorable.
(543) In summary, adhesion was higher in 8-12% PVP concentration. Higher silicone content offered better adhesion.
(544) Visual Indicators:
(545) As described herein, the masking agent formulation and/or the sealant composition may contain a colorant or dye. The colorant or dye may be any useful and medically suitable, e.g., biocompatible, dye. The dye may be biostable or may degrade over time after implantation in the body. Any useful color, such as blue, green, red, orange, and the like may be used. Further, the masking agent and/or sealant compositions may have an inherent color or tint which is distinguishable from medical grade textile yarns.
(546) Such a visually distinguishable masking agent and/or sealant compositions may be useful with the methods and products of the present invention. For example, visually distinguishable masking agent may be useful in ascertaining that the interior portions of a graft have sufficient masking agent coverage to inhibit sealant migration thereto. Such a visually distinguishable masking agent may also be useful in ascertaining that the exterior portions of the graft are free or substantially free of masking agent coverage so that the sealant composition may adequately cover the exterior of the graft, including securably covering the exterior of the graft to achieve substantially fluid impermeable sealing.
(547) A visually distinguishable sealant composition may be useful in ascertaining that exterior portions of the grant have sealant coverage. For example, a practitioner could differentiate between a non-sealed graft having the color, such as white, typical of medical textiles and a sealed graft of the present invention having a non-white color, such as blue, green, etc. Thus, a practitioner could readily distinguish between a permeable non-sealed graft and a substantially impermeable sealed graft of the present invention.
(548) If colorants or dyes are added to the masking agent and/or sealant compositions, then the levels of the colorants or dyes should not be at a level which interferes with the intended purpose of the masking agent and/or sealant compositions.
(549) Homogeneous Sealant Application and Coverage:
(550) Tests were performed to investigate the theory that the addition of the mask allows a thinner coating of silicone to be applied to the graft before a sufficient seal is obtained. This was done by applying silicone coatings at various target coverage levels and carrying out whole graft porosity on them to determine the level of seal. While the tests were performed with particular sealing and masking agents, any of the above-described sealing and masking agents may suitably be used.
(551) Tests were carried out on ATEX crimped and non-crimped polyester fabric as described below:
(552) ATEX Technologies Polyester Vascular Graft—14 mm Dia.—28.5 CPI
(553) ATEX Technologies Polyester Vascular Graft—14 mm Dia.—Uncrimped
(554) Equipment and Materials:
(555) 14 mm crimped polyester fabric (Atex Technologies)
(556) 14 mm non-crimped polyester fabric (ATEX Technologies)
(557) Polyvinylpyrrolidone (PVP) Powder
(558) De-ionised water
(559) MED6-6606 Silicone Dispersion
(560) n-Heptane
(561) Easy composite royal blue pigment
(562) Mandrels and mounts
(563) Hothouse (HH) Rotisserie
(564) Magnetic Stirrer
(565) Measuring jug
(566) Scales
(567) Blasting Cabinet
(568) Coating Variables:
(569) The presence of the masking agent has been shown to limit the penetration of the silicone through the graft structure as described earlier herein. The masking agent also appears to cause the silicone left on the surface to be more homogenous, resulting in a thinner coverage required to get a complete seal than with bare or non-masked fabric. Therefore, a range of silicone coverages was tested on a control of bare fabric and on grafts prepared with an optimised mask process. This was carried out on both crimped and non-crimped fabric to determine any differences.
(570) Control Graft Samples Preparation:
(571) Woven graft samples were coated with a 30% silicone dispersion in heptane (no mask). The silicone coverages targeted were 4, 6, 8, 10, and 12 mg/cm.sup.2.
(572) Optimized Mask Samples Preparation:
(573) Woven graft samples were prepared with mask (20% w/w PVP and 5% w/w Glycerol (to PVP) in water) applied using an immersion method. Once the mask was dried via rotation at room temperature, excess mask on the outer graft surface was soda blasted via sodium bicarbonate at 25-30 psig, while rotating the graft at 100 RPM. Blast particles were removed using a vacuum and heptane wash, then dried. Masked coated graft samples were sprayed coated with a 30% silicone/heptane dispersion. The silicone coverages targeted were 4, 6, 8, 10, 12 mg/cm.sup.2.
(574) Silicone Dispersion:
(575) Flushed spray head with n-heptane. Mounted graft and silicone/heptane dispersion syringe barrel in the spray rig. Sprayed silicone onto graft during rotation at 150 RPM and traverse 20 mm/s. Sprayed whole length of graft, then allowed heptane to flash off before making another pass (about 10 seconds). Repeated until no dispersion left in the syringe barrel. Dried for 6 hours with rotation and 66 hours stationary. Graft sample were dried if there was no vinegar odour.
(576) Removed mask via water wash at 90 degrees C. Warm water wash dissolved the PVP for removal and aided the silicone curing. Dried via ambient air.
(577) The most desirable mask process used a 20% PVP masking agent with 5% Glycerol (to PVP). The masking agent once dried was abraded with sodium bicarbonate soda at pressure of 25 to 30 psig. Details of the abrading process are described previously herein. The grafts were also coated with a 30% silicone dispersion. The decision for this process was taken from results presented earlier herein, where a 20% PVP masking agent performed well after abrasion and that at higher PVP concentrations a lower glycerol concentration was beneficial.
(578) Details for preparing (1) control graft samples and (2) masked graft samples for silicone coverage trials are listed below in Table 35.
(579) TABLE-US-00035 TABLE 35 Test Matrix HH Controls Optimised Mask Sam- Sam- Silicone Coverage Silicone Coverage ple ple (mg/cm.sup.2) (mg/cm.sup.2) ID ID 4 6 8 10 12 4 6 8 10 12 Crimped 1 220 X 2 221 X 3 222 X 4 223 X 5 224 X 6 225 X 7 226 X 8 227 X 9 228 X 10 229 X Un- 11 230 X Crimped 12 231 X 13 232 X 14 233 X 15 234 X 16 235 X 17 236 X 18 237 X 19 238 X 20 239 X
(580) Method:
(581) Sample Preparation:
(582) Each sample was removed from the store and assigned a HH sample ID number. Each sample was to be made up of half a graft. Firstly, the graft was cut in half. The graft was fully stretched removing the crimp, if applicable, and cut at the midpoint with a single edge razor blade, once cut the end was cauterized to prevent fraying. The samples were clean and free of any debris. The weights of Cut graft sections were recorded. Each sample was marked with sample IDs.
(583) The control samples were put to the side ready for mounting.
(584) Masking Agent Preparation:
(585) To aid the abrasion of the mask it was beneficial to have some sort of dye in the masking agent. The reason for this is that it gives a visual aid into how much is being removed.
(586) To prepare the masking agent formulation, the following steps were followed:
(587) Placed 200 ml of de-ionised water into a 100 ml plastic beaker.
(588) Placed Magnetic stirrer in the water and place the beaker on the magnetic stirrer.
(589) Turned the magnetic stirrer on at a speed of approx. 400 RPM at room temperature.
(590) Measured 40 g of PVP and 4 g of glycerol onto weighing boats.
(591) Added the PVP and Glycerol to the water.
(592) Added 2 drops of yellow dye.
(593) Stirred till there was no solute visible.
(594) Masking Agent Application and Drying:
(595) After the mask was fully prepared, the graft was coated. This was done by immersing the graft within the masking agent solution and agitating the graft by gloved hands, so it is fully coated inside and out.
(596) Once the graft was saturated, the excess mask solution was removed by running the graft between a thumb and index finger. Next the graft was to be attached to a mandrel, this was done using cable ties. Cable tied one end of the graft to the mandrel, in the case of the crimped grafts, extended the graft to 60% of its overall extended length, and cable tied the other end of the graft to the mandrel. The mandrel was then be placed horizontally on the rotisserie and allowed to air dry for 12 hours. Once dried, the weight of the masked graft was recorded.
(597) The dry masked graft were then mounted on a solid mandrel and cable tied in place. The mandrel was mounted within the blasting cabinet attached to the rotating chuck and set to a speed of approximately 100 RPM. The soda blaster (or sodium bicarbonate abrader) was filled with bicarbonate of soda and set to a pressure of 25 to 30 psig. The graft was then be rotated and the soda blast gun traversed over the surface at a sufficient speed to not miss any of the surface, once one full pass was made, repeated the traverse for a second time. It should be noted that the pressure of the abrader for the present invention may be as high as 50 psig, which in some cases will affect the integrity of the underlying textile but may be acceptable depending on the remaining structural integrity, of the textile.
(598) After the blasted grafts have been ablated, they were washed to remove any particulates of mask or bicarbonate of soda that was still on the surface. This was done by first passing a vacuum over the surface then pouring heptane over the outside of the graft.
(599) After washing the graft, the graft was allowed to dry then be weighed again, and the weight noted on the test sheet.
(600) Once the masked graft was dried and weighed it was mounted back onto the suspended mandrel. At this point the control samples were also mounted onto the appropriate mandrel to match the target silicone coverage as per the test matrix.
(601) Sealant Preparation:
(602) The sealant came supplied as a 30 wt % silicone in heptane and was used as is.
(603) The appropriate amount of silicone was measured out to give the target coverage as per the test matrix and it was loaded into one of the disposable syringe barrels. These amounts were set to account for a 25% loss when spraying.
(604) Sealant Application:
(605) The spray head was flushed with n-Heptane to ensure correct flow. The mandrel with the graft was then mounted in the spray rig. The spray rig was set up to spray the entire length of graft. Mounted the syringe barrel with silicone onto the spray head. The graft was rotated at 150 RPM and the rate of traverse was set to 20 mm/s. The spray head was started and traversed over the entire length of the graft, once it reached the opposite end the spray head was stopped and allowed to return to the start of the graft. The solvent was allowed to flash off before making another pass, after each pass a delay of 10 seconds was observed. This was continued till there was no dispersion left in the syringe barrel or there was an insufficient amount to make another full pass. Once the graft was removed from the spray rig the spray head was again flushed with n-heptane.
(606) After application the graft was transferred to the rotisserie for a period of 6 hours then transferred to a stationary mount and allowed to air dry for a further 66 hours, the graft was confirmed dry if it did not have a perceptible vinegar odour coming from it. Once dry, the sealed graft was weighed and the weight recorded.
(607) Mask Removal:
(608) Once the graft has been fully dried the mask was removed. This was done by washing the grafts in a washing machine on a ‘cotton cycle’ at 90° C. (with no detergent). This caused the PVP to be dissolved in the water and removed and also the high temperatures aided the curing of the silicone. When the wash was complete, the graft was hung up to air dry. Once the mask had been removed and the graft was dry, the finished graft was weighed and the weight recorded.
(609) Assessment of Handling:
(610) The handling of crimped grafts was assessed using tensile extension force testing. Mounted crimped graft samples between jaws of Lloyd Tensile Test machine. Extend jaws by 20% (16 mm) and measure maximum force.
(611) Permeability Testing (ISO 7198—Whole Graft Leak Testing):
(612) Permeability was assessed via a whole graft porosity test (ISO 7198). Connected the graft to the pressure rig and ensure there are no leaks. Slowly increased pressure to 120 mmHg, once at that pressure the leakage, if any, from the graft surface was measured over the period of 1 minute and recorded on the test sheet. Once the leak rate was obtained, this was divided by the test surface area to obtain the permeability reading.
(613) Delamination Testing:
(614) Delamination was assessed via a whole graft porosity test. Connected the graft to the pressure rig and ensured there are no leaks. Slowly increased pressure to 600 mmHg, once at that pressure the leakage, if any, from the graft surface was measured over the period of 1 minute and recorded on the test sheet. Once the leak rate was obtained, this was divided by the test surface area to obtain the permeability reading.
(615) Results & Analysis:
(616) The data in the table below demonstrated the ability to get a consistent mask coverage over a range of samples and obtain the target coverage levels of silicone.
(617) Table 36 below lists the measured weights of the masking agent and sealant formulations after the noted processing steps. Masking agent and sealant coverages are noted in the table.
(618) TABLE-US-00036 TABLE 36 Weight Summary After After After Masking Sealant Washing and and and Mask Silicone Target Sample Initial Drying Curing Drying Coverage Coverage Silicone ID HH ID (mg) (mg) (mg) (mg) (mg/cm.sup.2) (mg/cm.sup.2) Coverage 1 220 2699 2699 3417 3412 0.00 3.64 4 2 221 2665 2665 3881 3878 0.00 6.23 6 3 222 2729 2729 4398 4396 0.00 8.44 8 4 223 2679 2679 4569 4564 0.00 9.81 10 5 224 2683 2683 4872 4868 0.00 11.27 12 6 225 2646 3393 4127 3374 3.90 3.81 4 7 226 2641 3382 4382 3651 3.86 5.27 6 8 227 2674 3367 4910 4205 3.59 7.93 8 9 228 2692 3385 5538 4840 3.56 11.02 10 10 229 2700 3314 6083 5454 3.12 14.01 12 11 230 1756 1756 2101 2093 0.00 2.39 4 12 231 1767 1767 2576 2574 0.00 5.73 6 13 232 1745 1745 2757 2747 0.00 7.12 8 14 233 1700 1700 3199 3200 0.00 10.66 10 15 234 1699 1699 3432 3438 0.00 12.36 12 16 235 1716 2020 2611 2294 2.16 4.11 4 17 236 1735 2027 2918 2597 2.07 6.12 6 18 237 1711 1998 3215 2892 2.04 8.39 8 19 238 1712 2005 3487 3167 2.08 10.34 10 20 239 1728 2035 3773 3437 2.18 12.14 12
(619) Results from the table above demonstrate all woven PET graft samples had a consistent mask coverage. Crimped graft samples (samples 6-10) generally held more mass of mask compared to uncrimped graft samples (samples 17-20). This may be caused from the topography of the crimped graft. The above table demonstrated the ability to get a consistent mask coverage over a range of samples and also to be able to target the coverage levels of silicone. As the masked samples were blasted the following table shows the weight data for that also.
(620) Additionally, all woven PET graft sample achieved actual silicone coverage levels close to the target silicone coverage levels. Crimped grafts tended to have slightly less actual silicone coverage compared to its target silicone coverage. On the other hand, uncrimped grafts tended to have slightly more actual silicone coverage compared to its target silicone coverage. This observation may be related to the mask coverage. Less mask coverage, as seen in the uncrimped samples, allowed for higher silicone attachment to the PET graft.
(621) As the masked graft samples were soda blasted, the following table shows the weight before and after ablation.
(622) Results for graft sample mass measurements before and after ablation are listed below in Table 37.
(623) TABLE-US-00037 TABLE 37 After Weight Masking After difference Sample HH Initial and Drying Ablation after ablation ID ID (mg) (mg) (mg) (mg) 6 225 2699 3393 3424 −31 7 226 2665 3382 3407 −25 8 227 2729 3367 3402 −35 9 228 2679 3385 3416 −31 10 229 2683 3314 3351 −37 16 235 2646 2020 2054 −34 17 236 2641 2027 2073 −46 18 237 2674 1998 2043 −45 19 238 2692 2005 2044 −39 20 239 2700 2035 2081 −46
(624) The ablation weight data table above, shows that there was consistent weight gain for each of the 10 ablated samples. This suggested that although the mask is being ablated that there is also bicarbonate being deposited on the surface.
(625) Handling:
(626) The handling of the crimped grafts was assessed using the same technique as described above, although for this report the whole graft was considered and not a section of 80 mm. The same 20% extension was used; therefore, the results are comparable. The table below shows the results of this testing.
(627) The results showed that for both sets of grafts, with increasing silicone coverages an increased in the force to extend was measured. Also evident was the increase in the force to extend between the controls and the grafts with an optimized mask. The controls required roughly double the force for the same 20% extension, strengthening the theory that higher levels of penetration result in a higher force to extend, and furthermore worse handling.
(628) Table 38 lists forces-to-extend values for the various samples tested.
(629) TABLE-US-00038 TABLE 38 Force Glyc- to Extend PVP erol Force (Normalised HH Mask Conc. Silicone to with Sample Sample Conc. (% of Coverage Extend Circumference) ID ID (%) PVP) (mg/cm.sup.2) (N) (N/mm) 1 220 0 0 3.64 0.47739 0.011 2 221 0 0 6.23 0.66692 0.015 3 222 0 0 8.44 0.72483 0.016 4 223 0 0 9.81 0.67862 0.015 5 224 0 0 11.27 0.69653 0.016 6 225 20 5 3.81 0.17895 0.004 7 226 20 5 5.27 0.20019 0.005 8 227 20 5 7.93 0.21045 0.005 9 228 20 5 11.02 0.34497 0.008 10 229 20 5 14.01 0.39559 0.009
(630) The force-to-extend results show that all crimped graft samples tested increase the amount of force to extend with increasing silicone coverages. Additionally, the crimped graft samples with mask (samples 1-5) decreased the amount of force to extend compared to the crimped graft samples without mask (samples 6-10). The controls (crimp grafts with no mask) require roughly double the force for the same 20% extension compared to crimp grafts with mask. This testing strengthens the theory that higher levels of silicone penetration results in a higher force to extend, and furthermore worse handling properties.
(631) As depicted in
(632) Permeability Testing (ISO 7198—Whole Graft Leak Testing):
(633) The below table shows the results of the permeability testing carried out on all 20 samples. As expected the low coverages on the unmasked grafts gave high permeability reading compared to the masked equivalents. On higher silicone coverage levels the permeability was more comparable.
(634) Results for permeability testing (ISO 7198) are listed below in Table 39.
(635) TABLE-US-00039 TABLE 39 PVP Mask Glycerol HH Concen- Concen- Silicone Sample Sample tration tration Coverage Permeability ID ID (%) (% of PVP) (mg/cm.sup.2) (ml/min/cm.sup.2) 1 220 — — 3.64 12.82 2 221 — — 6.23 0.97 3 222 — — 8.44 0.48 4 223 — — 9.81 0.76 5 224 — — 11.27 0.16 6 225 20 5 3.81 2.05 7 226 20 5 5.27 0.42 8 227 20 5 7.93 5.37 9 228 20 5 11.02 0.04 10 229 20 5 14.01 0.00 11 230 — — 2.39 22.08 12 231 — — 5.73 10.25 13 232 — — 7.12 0.55 14 233 — — 10.66 0.00 15 234 — — 12.36 0.00 16 235 20 5 4.11 1.36 17 236 20 5 6.12 0.38 18 237 20 5 8.39 0.05 19 238 20 5 10.34 0.02 20 239 20 5 12.14 0.05
(636) Crimped graft and uncrimped grafts with no mask and low silicone coverage (3-6 mg/cm.sup.2) demonstrated high permeability reading compared to the masked graft equivalents. Therefore, it is observed that the application of masking agent lowers the amount of silicone needed to seal the graft.
(637) Silicone coverage seals the graft with mask or without mask at about 8 mg/cm.sup.2. With higher silicone coverage (>7 mg/cm.sup.2), the permeability is more comparable for masked and non-masked graft samples.
(638) Sample 8 (crimped graft with mask) gave an unexpected result. The permeability for this sample is higher than any other graft at that concentration. Sample 8 was expected to be one of the lowest permeability results. This permeability result does not follow the pattern of other grafts with similar silicone coverage (6 mg/cm.sup.2 and 10 mg/cm.sup.2). No obvious pattern of leakage was observed. It is suggested there was an issue with the silicone itself or the application method used. A hypothesis is that the silicone sat too long in air whilst spraying or there was a blockage during spraying that has caused the coating to fail.
(639) Delamination Testing:
(640) The table below shows the results of the delamination testing carried out on select crimped graft samples.
(641) Results for delamination testing detailed below in Table 40.
(642) TABLE-US-00040 TABLE 40 Silicone Test Hothouse Soda Coverage Leakage @ Sample ID Sample ID Mask blast mg/cmsq 600 mmHg 2 221 No No 6 395 ml 5 224 No No 12 43 ml 7 226 20% 30 psi 6 1800 ml 133 20% 50 psi 7 95
(643) Conclusions:
(644) All silicone coated samples with masking agent and without masking agent did not delaminate at 600 mmHg. In other words, all samples passed the delamination test. The silicone coated samples with masking agent and without masking agent may have had very minor, for example 1 to six, fine micro-jets of leakage at 600 mmHg. Nevertheless, all samples still passed the delamination test. Masking agent application and blasting or ablating processes did not compromise the silicone attachment to the grafts. Higher blasting pressures provided an increased amount of non-masked fibres on the outer surface of the graft for a stronger silicone attachment and significantly less leakage at 600 mmHg. Soda blasting at 50 psi caused minor breakage of fibres which improved silicone attachment (decreased leakage amount) and provided better handleability of the graft.
(645) Immersion of the textile graft into the masking agent showed a consistent method of applying PVP to crimped and uncrimped graft samples. Spray method using force air showed an accurate way of achieving target coverage levels of silicone. Decreasing silicone coverage improved handling slightly. The addition of the mask improved handling by reducing penetration of the silicone. Crimped and uncrimped fabric have similar permeability levels at corresponding silicone coverages. The addition of masking agent results in lower permeability values at lower silicone coverages. At higher silicone coverages the addition of masking agent has less effect.
(646) In summary, the water soluble masking agent may have a viscosity from about 2,000 centipoise at room temperature to about 100,000 centipoise at room temperature, including from about 50,000 centipoise at room temperature to about 100,000 centipoise at room temperature. The water soluble masking agent may comprise from about 25% w/w of the polyvinylpyrrolidone in the glycerol to about 75% w/w of the polyvinylpyrrolidone in glycerol, including from about 30% w/w of the polyvinylpyrrolidone in the glycerol to about 70% w/w of the polyvinylpyrrolidone in glycerol, including from about 40% w/w of the polyvinylpyrrolidone in the glycerol to about 60% w/w of the polyvinylpyrrolidone in glycerol, more desirably including from about 45% w/w of the polyvinylpyrrolidone in the glycerol to about 55% w/w of the polyvinylpyrrolidone in glycerol, in particular about 50% w/w of the polyvinylpyrrolidone in the glycerol. The polyvinylpyrrolidone may have a molecular weight of from about 2,500 g/mol to about 55,000 g/mol, including from about 3,500 g/mol to about 50,000 g/mol, from about 5,000 g/mol to about 40,000 g/mol, from about 5,000 g/mol to about 30,000 g/mol, from about 5,000 g/mol to about 20,000 g/mol, and desirably from about 8,000 g/mol to about 10,000 g/mol.
(647) Modifications may be made to the foregoing embodiments within the scope of the present invention.
(648) The following embodiments or aspects of the invention may be combined in any fashion and combination and be within the scope of the present invention, as follows:
(649) Embodiment 1. A method of manufacturing a tubular graft comprising the steps of:
(650) providing a textile comprising a tubular wall disposed between a first open end and an opposed second open end, an inner surface and an opposed outer surface defining an interior wall portion therein between, the tubular wall comprising a textile construction of one or more filaments or yarns, the textile construction by itself being permeable to liquid;
(651) applying a substantially water-soluble material to at least a portion of the tubular wall; and
(652) applying a substantially water-insoluble sealant to at least a part of the outer surface of the tubular wall, the substantially water-insoluble sealant being configured to mitigate movement of fluid through the wall of the conduit;
(653) wherein the water-soluble material is configured to mitigate penetration of the sealant to the inner surface of the conduit.
(654) Embodiment 2. The method of embodiment 1, wherein the step of applying the water-soluble material to at least a portion of the tubular wall comprises applying the water-soluble material to at least a portion of the inner surface and a portion of the interior portion of the tubular wall.
(655) Embodiment 3. The method of embodiment 1 or 2, wherein the step of applying the water-soluble material to at least a portion of the tubular wall comprises applying the water-soluble material to at least a portion of the outer surface of the tubular wall.
(656) Embodiment 4. The method of any preceding embodiment, wherein the water-soluble material is a solution of the water-soluble material and a solvent.
(657) Embodiment 5. The method of any preceding embodiment, wherein the solvent is selected form the group consisting of water, lower alcohols, and combinations thereof.
(658) Embodiment 6. The method of any preceding embodiment, wherein the solvent is at least partially removed prior to applying the substantially water-insoluble sealant.
(659) Embodiment 7. The method of any preceding embodiment, further comprising removal of at least a portion of the water-soluble material is by dissolution, abrading, peeling, degrading, and combinations thereof.
(660) Embodiment 8. The method of any preceding embodiment, wherein the water-soluble material is selected from the group consisting of polyvinylpyrrolidone, glycerol, methyl cellulose, poly(ethylene glycol), poly(ethylene glycol) hydrogel, polyethylene oxide, and combinations thereof.
(661) Embodiment 9. The method of any preceding embodiment, wherein the substantially water-insoluble sealant is an elastomeric material selected from the group consisting of moisture curing, light curing, thermo-curing, platinum catalyzed, anaerobic curing materials or a combination of these curing mechanisms.
(662) Embodiment 10. The method of embodiment 9, wherein the elastomeric material is selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof.
(663) Embodiment 11. The method of any preceding embodiment, wherein one of more of the substantially water-soluble coating or the substantially water-insoluble coating further comprises a component selected from the group consisting of a colorant, a therapeutic agent, a dye, and a fluorescent indicator.
(664) Embodiment 12. The method of any preceding embodiment, wherein the water-soluble material comprises polyvinylpyrrolidone having a molecular weight of between approximately 6,000 g/mol and approximately 15,000 g/mol.
(665) Embodiment 13. The method of any preceding embodiment, wherein applying the water-soluble material forms layer on substantially all of the inner surface of the tubular wall.
(666) Embodiment 14. The method of any preceding embodiment, further comprising curing the substantially water-insoluble sealant.
(667) Embodiment 15. The method of any preceding embodiment, further comprising curing the substantially water-insoluble sealant; and thereafter removing at least a portion of the water-soluble material.
(668) Embodiment 16. The method of embodiment 14, further comprising removing substantially all of the water-soluble material from the inner surface of the tubular wall.
(669) Embodiment 17. The method of any preceding embodiment, further comprising:
(670) removing at least a part of the water-soluble material from at least a part of the outer surface of the tubular wall prior to the applying the substantially water-insoluble sealant.
(671) Embodiment 18. The method of any one of embodiments 15 to 17, wherein the removing at least the portion of the water-soluble material is carried out at a temperature of between approximately 15° C. and approximately 140° C.
(672) Embodiment 19. The method of any one of embodiments 15 to 18, wherein the removing at least the portion of the water-soluble material further comprises the step of applying a solvent thereto.
(673) Embodiment 20. The method of embodiment 19, wherein the solvent comprises water, lower alcohols, and combinations thereof.
(674) Embodiment 21. The method of any one of embodiments 15 to 20, wherein the tubular textile is agitated, rotated, spun, and shaken, or the like, during the removal of the water-soluble material.
(675) Embodiment 22. The method of any one of embodiments 15 to 21, wherein the removal of the water-soluble material comprises dissolving, etching, plasma etching, ablating, abrading and combinations thereof of the water-soluble material.
(676) Embodiment 23. The method of any preceding embodiment, wherein the step of applying the water-soluble material further comprises spraying the water-soluble material, brushing the water-soluble material, immersing at least a portion of the tubular wall into a solution of the water-soluble material, and combinations thereof.
(677) Embodiment 24. The method of any preceding embodiment, wherein the substantially water-insoluble sealant is a polymer solution.
(678) Embodiment 25. The method of embodiment 24, wherein the polymer solution comprises an organic solvent.
(679) Embodiment 26. The method of embodiment 25, wherein the organic solvent comprises at least one of heptane and xylene.
(680) Embodiment 27. The method of any preceding embodiment, wherein the substantially water-insoluble sealant is applied by brushing, spraying, roller coating the substantially water-insoluble sealant thereon.
(681) Embodiment 28. The method of any preceding embodiment, wherein the method comprises one or more steps of selectively applying the substantially water-insoluble sealant to one or more portions of the tubular wall, such that the tubular wall comprises at least two sections having substantially different amounts of the substantially water-insoluble sealant thereon.
(682) Embodiment 29. The method of any one of embodiments 14 to 28, wherein the tubular wall having the coating of the substantially water-insoluble sealant is, after curing thereof, substantially impermeable to liquid.
(683) Embodiment 30. The method of any preceding embodiment, wherein, after curing of the substantially water-insoluble sealant, the tubular wall has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(684) Embodiment 31. A textile comprising:
(685) a tubular wall disposed between a first open end and an opposed second open end and having an inner surface and an opposed outer surface, the tubular wall comprising a textile construction of one or more filaments or yarns, the textile construction by itself being permeable to liquid;
(686) wherein a portion of the inner surface comprises a coating of a substantially water-soluble material thereon;
(687) wherein the outer surface further comprises a coating of a substantially water-insoluble sealant disposed thereon; and
(688) wherein the tubular wall having the coating of the substantially water-insoluble sealant is, after curing thereof, substantially impermeable to liquid.
(689) Embodiment 32. The textile of embodiment 31, wherein the water-soluble material is selected from the group consisting of polyvinylpyrrolidone, glycerol, methyl cellulose, poly(ethylene glycol), poly(ethylene glycol) hydrogel, polyethylene oxide, and combinations thereof.
(690) Embodiment 33. The textile of embodiment 31 or 32, wherein the coating of the water-soluble material comprises an oleophobic layer.
(691) Embodiment 34. The textile of any one of embodiments 31 to 33, wherein the water-soluble material comprises polyvinylpyrrolidone having a molecular weight of between approximately 6,000 g/mol and approximately 15,000 g/mol.
(692) Embodiment 35. The textile of any one of embodiments 31 to 34, the water-soluble material comprises polyvinylpyrrolidone and glycerol.
(693) Embodiment 36. The textile of any one of embodiments 31 to 35, wherein the substantially water-insoluble sealant is an elastomeric material selected from the group consisting of moisture curing, light curing, thermo-curing, platinum catalyzed, anaerobic curing materials or a combination of these curing mechanisms.
(694) Embodiment 37. The textile of embodiment 36, wherein the elastomeric material is selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof.
(695) Embodiment 38. The textile of any one of embodiments 31 to 37, wherein one of more of the substantially water-soluble coating or the substantially water-insoluble coating comprises a component selected from the group consisting of a colorant, a therapeutic agent, a dye, and a fluorescent indicator.
(696) Embodiment 39. The textile of any one of embodiments 31 to 38, wherein, after curing of the substantially water-insoluble sealant, the tubular wall has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(697) Embodiment 40. The textile of any one of embodiments 31 to 39, wherein the textile construction is selected from the group consisting of a weave of the one or more filaments or yarns, a knit of the one or more filaments or yarns, a braid of the one or more filaments or yarns, and a web of the one or more filaments or yarns.
(698) Embodiment 41. The textile of any one of embodiments 31 to 40, wherein the tubular wall is a crimped wall having a series of peaks and valleys.
(699) Embodiment 42. The textile of embodiment 41, wherein the substantially water-insoluble sealant is disposed at about 8 mg/cm.sup.2 of area of the tubular wall or greater than 8 mg/cm.sup.2 of area of the tubular wall.
(700) Embodiment 43. The textile of any one of embodiments 31 to 40, wherein the tubular wall is a non-crimped wall being substantially free of peaks and valleys.
(701) Embodiment 44. The textile of embodiment 43, wherein the substantially water-insoluble sealant is disposed at about 4 mg/cm.sup.2 of area of the tubular wall or greater than 4 mg/cm.sup.2 of area of the tubular wall.
(702) Embodiment 45. The textile of any one of embodiments 31 to 44, wherein the substantially water-insoluble sealant is disposed at about 14 mg/cm.sup.2 of area of the tubular wall or less than 14 mg/cm.sup.2 of area of the tubular wall.
(703) Embodiment 46. The textile of any one of embodiments 31 to 45,
(704) wherein one portion of the tubular wall has a first level of the substantially water-insoluble sealant to provide a first soft, flexible zone;
(705) wherein another portion of the tubular wall has a second level of the substantially water-insoluble sealant to provide a second zone having a stiffness greater than the first zone; and
(706) wherein the second level the substantially water-insoluble sealant is greater than the first level of the substantially water-insoluble sealant.
(707) Embodiment 47. The textile of any one of embodiments 31 to 46, wherein at least a portion of the coating of the substantially water-insoluble sealant engages at least a portion of the one or more filaments or yarns.
(708) Embodiment 48. The textile of any one of embodiments 31 to 47, where in the textile is an implantable medical device.
(709) Embodiment 49. The textile of embodiment 48, wherein the implantable medical device is selected from the group consisting of surgical vascular grafts, and endovascular graphs, meshes, patches, hernia plugs, vascular wraps, heart valves, filters, and the like.
(710) Embodiment 50. The textile of any one of embodiments 31 to 49, wherein the textile is a delivery medical device.
(711) Embodiment 51. The textile of embodiment 50, wherein the delivery medical device is a catheter.
(712) Embodiment 52. A textile structure comprising:
(713) a fluid permeable polymeric textile layer having opposing first and second surfaces and a length;
(714) a cross-linkable water-insoluble elastomeric layer on the first textile surface configured to render the liquid permeable polymeric textile layer substantially impermeable to fluid when cured; and
(715) a substantially dried water-soluble polymer layer on the second textile surface;
(716) wherein water-soluble polymer layer substantially inhibits migration of the water-insoluble elastomeric layer onto the second surface; and
(717) wherein the water-soluble polymer layer is substantially removable by exposure to water.
(718) Embodiment 53. The textile structure of embodiment 52, wherein the weight ratio of the cross-linkable water-insoluble elastomeric polymer to the water-soluble polymer is from about 0.1:1 to about 100:1.
(719) Embodiment 54. The textile structure of embodiment 53, wherein the weight ratio of the cross-linkable water-insoluble elastomeric polymer to the water-soluble polymer is from about 1:1 to about 20:1.
(720) Embodiment 55. A textile structure comprising:
(721) a fluid permeable polymeric textile layer having opposing first and second surfaces and a length;
(722) a crosslinked water-insoluble elastomeric polymer layer on the first textile surface forming a substantially fluid impermeable barrier, wherein the crosslinked water-insoluble elastomeric layer is adhered to the first textile surface by elastomeric shrinkage; and
(723) a water dissolvable polymer layer dried on the second textile surface;
(724) wherein the weight ratio of the crosslinked water-insoluble elastomeric polymer to the water dissolvable polymer is from about 0.1:1 to about 100:1.
(725) Embodiment 56. The textile construction of embodiment 55, wherein the weight ratio of the crosslinked water-insoluble elastomeric polymer to the water dissolvable polymer is from about 1:1 to about 20:1.
(726) Embodiment 57. A graft comprising:
(727) a tubular wall disposed between a first open end and an opposed second open end and having an inner surface and an opposed outer surface, the tubular wall comprising a textile construction of one or more filaments or yarns;
(728) wherein the outer surface comprises a coating of a substantially water-insoluble sealant disposed thereon;
(729) wherein the inner surface is substantially free of the substantially water-insoluble sealant; and
(730) wherein the tubular wall has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(731) Embodiment 58. The graft of embodiment 57, wherein the textile construction is selected from the group consisting of a weave of the one or more filaments or yarns, a knit of the one or more filaments or yarns, a braid of the one or more filaments or yarns, and a web of the one or more filaments or yarns.
(732) Embodiment 59. The graft of embodiment 57 or 58, wherein the coating is disposed within an intermediate portion of the tubular wall between the inner surface and the opposed outer surface.
(733) Embodiment 60. The graft of any one of embodiments 57 to 59, wherein the tubular wall is a crimped wall having a series of peaks and valleys.
(734) Embodiment 61. The graft of any one of embodiments 57 to 60, wherein the substantially water-insoluble sealant is disposed at about 8 mg/cm.sup.2 of area of the tubular wall or greater than 8 mg/cm.sup.2 of area of the tubular wall.
(735) Embodiment 62. The graft of any one of embodiments 57 to 59, wherein the tubular wall is a non-crimped wall being substantially free of peaks and valleys.
(736) Embodiment 63. The graft of any one of embodiments 57 to 62, wherein the substantially water-insoluble sealant is disposed at about 4 mg/cm.sup.2 of area of the tubular wall or greater than 4 mg/cm.sup.2 of area of the tubular wall.
(737) Embodiment 64. The graft of any one of embodiments 57 to 63, wherein the substantially water-insoluble sealant is disposed at about 14 mg/cm.sup.2 of area of the tubular wall or less than 14 mg/cm.sup.2 of area of the tubular wall.
(738) Embodiment 65. The graft of any one of embodiments 57 to 64, wherein the substantially water-insoluble sealant is an elastomeric material selected from the group consisting of moisture curing, light curing, thermo-curing, platinum catalyzed, anaerobic curing materials or a combination of these curing mechanisms.
(739) Embodiment 66. The graft of embodiment 65, wherein the elastomeric material is selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof.
(740) Embodiment 67. The graft of any one of embodiments 57 to 66, wherein one of more of the substantially water-soluble coating or the substantially water-insoluble coating comprises a component selected from the group consisting of a colorant, a therapeutic agent, a dye, and a fluorescent indicator.
(741) Embodiment 68. The graft of any one of embodiments 57 to 67, wherein the substantially water-insoluble sealant is selected from the group consisting of silicone, room temperature vulcanizing silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, polycarbonate, and combinations thereof.
(742) Embodiment 69. The graft of any one of embodiments 57 to 69, wherein one portion of the tubular wall has a first level of the substantially water-insoluble sealant to provide a first soft, flexible zone;
(743) wherein another portion of the tubular wall has a second level of the substantially water-insoluble sealant to provide a second zone having a stiffness greater than the first zone; and
(744) wherein the second level the substantially water-insoluble sealant is greater than the first level of the substantially water-insoluble sealant.
(745) Embodiment 70. An implantable or deliverable medical textile comprising:
(746) a wall having a textile construction and having a first surface and an opposed second surface;
(747) wherein the second surface comprises a coating of a substantially water-insoluble sealant disposed thereon;
(748) wherein the first surface is substantially free of the substantially water-insoluble sealant; and
(749) wherein the wall has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(750) Embodiment 71. An assembly for producing an implantable or deliverable medical textile having a selectively applied water-insoluble sealant layer, comprising:
(751) a mandrel having a length, a hollow lumen disposed within a portion of the length, at least one open end, and a plurality of perforations through a wall of the mandrel;
(752) a reservoir in fluid communication with the open lumen of the mandrel; and
(753) a water-soluble polymer disposed within the reservoir.
(754) Embodiment 72. The assembly of embodiment 71, further comprising a tubular graft securably disposed over a portion of the mandrel having the plurality of perforations.
(755) Embodiment 73. The assembly of embodiment 71 or 72, further comprising a vacuum source in fluid communication with the hollow lumen of the mandrel.
(756) Embodiment 74. The assembly of embodiment 73, further comprising a manifold configured to provide selective fluid communication between the hollow lumen of the mandrel and the reservoir and/or the vacuum source.
(757) Embodiment 75. The assembly of any one of embodiments 71 to 74, further comprising a source of pressurized and/or blown air.
(758) Embodiment 76. The assembly of embodiment 75, wherein the pressurized and/or blown air is in fluid communication with the hollow lumen of the mandrel.
(759) Embodiment 77. The method, textile, graft, device or assembly of any preceding embodiment, further including a support member.
(760) Embodiment 78. The method of any one of embodiments 1 to 30, wherein the support member is added to the outer surface of the wall of the conduit.
(761) Embodiment 79. The method of embodiment 78, wherein the support member is wrapped around the outer surface of the wall of the conduit.
(762) Embodiment 80. The method of embodiment 79, wherein the conduit comprises a plurality of crimps, and the support member is arranged to nest between the plurality of crimps.
(763) Embodiment 81. The method of any one of embodiments 78 to 80, wherein a step of adding the support member to the conduit is carried out prior to the step of adding the sealant to the conduit.
(764) Embodiment 82. The method of any one of embodiments 78 to 81, wherein a step of adding the sealant to the conduit is used, at least in part, to attach the support member to the conduit.
(765) Embodiment 83. The method of any one of embodiments 78 to 82, wherein the support member is a flexible, polymer member.
(766) Embodiment 84. The method of any one of embodiments 78 to 83, wherein the flexible support member is present on a portion of the length of the graft.
(767) Embodiment 85. A method of manufacturing a vascular prosthesis, the method comprising the steps of:
(768) (i) providing a conduit comprising a wall, the wall of the conduit comprising an inner surface and an outer surface, at least a section of the conduit being porous;
(769) (ii) adding a masking agent to at least a part of the porous section of the conduit; and
(770) (iii) adding a sealant to at least a part of the porous section of the conduit, the sealant being configured to mitigate movement of fluid through the wall of the conduit;
(771) wherein the masking agent is configured to mitigate presence of the sealant on the inner surface of the conduit.
(772) Embodiment 86. The method of embodiment 85, wherein the sealant forms a sealing layer on at least a part of the outer surface of the wall of the conduit.
(773) Embodiment 87. The method of embodiment 85 or embodiment 86, wherein the sealant forms a sealing layer on substantially all of the outer surface of the wall of the conduit.
(774) Embodiment 88. The method of any preceding embodiments 85 to 87, wherein the masking agent forms a masking agent layer on at least a part of the inner surface of the wall of the conduit.
(775) Embodiment 89. The method of any preceding embodiments 85 to 88, wherein the masking agent forms a masking agent layer on substantially all of the inner surface of the wall of the conduit.
(776) Embodiment 90. The method of any preceding embodiments 85 to 89, wherein substantially all of the conduit is porous.
(777) Embodiment 91. The method of any preceding embodiments 85 to 90, wherein the method comprises one or more masking agent removal steps, the, or each, masking agent removal step comprising the step of removing at least a part of the masking agent from the conduit.
(778) Embodiment 92. The method of embodiment 91, wherein the method comprises the step of removing at least a part of the masking agent from at least a part of the outer surface of the wall of the conduit prior to the step of adding the sealant to the porous section of the conduit.
(779) Embodiment 93. The method of embodiment 91 or embodiment 92, wherein the method comprises the step of removing at least a part of the masking agent from the inner surface of the wall of the conduit subsequent to the step of adding the sealant to at least a part of the porous section of the conduit.
(780) Embodiment 94. The method of any one of embodiments 91 to 93, wherein the method comprises the step of removing substantially all of the masking agent from the conduit subsequent to the step of adding the sealant to at least a part of the porous section of the conduit.
(781) Embodiment 95. The method of any one of embodiments 91 to 94, wherein at least one of the masking agent removal steps is carried out at a temperature of between approximately 15° C. and approximately 140° C.
(782) Embodiment 96. The method of any one of embodiments 91 to 95, wherein at least one of the masking agent removal steps comprises the step of removing at least a part of the masking agent by applying a solvent thereto.
(783) Embodiment 97. The method of embodiment 96, wherein the solvent comprises water.
(784) Embodiment 98. The method of any one of embodiments 91 to 97, wherein the conduit is at least one of: agitated, rotated, spun, and shaken, or the like, during at least one of the masking agent removal steps.
(785) Embodiment 99. The method of any one of embodiments 91 to 98, wherein at least one of the masking agent removal steps is carried out by etching, plasma etching, ablating and/or abrading the masking agent.
(786) Embodiment 100. The method of any preceding embodiments 85 to 99, wherein the inner surface of the wall of the conduit is configured to promote the growth of biological tissue thereon.
(787) Embodiment 101. The method of any preceding embodiments 85 to 100, wherein the masking agent comprises a polymer.
(788) Embodiment 102. The method of embodiment 101, wherein the masking agent comprises a water-soluble polymer.
(789) Embodiment 103. The method of embodiment 101 or embodiment 102, wherein the masking agent comprises at least one of: polyvinylpyrrolidone, glycerol, methyl cellulose, poly(ethylene glycol), and poly(ethylene glycol) hydrogel.
(790) Embodiment 104. The method of any preceding embodiments 85 to 103, wherein the masking agent is biocompatible.
(791) Embodiment 105. The method of any preceding embodiments 85 to 104, wherein the masking agent forms a biocompatible masking agent layer when added to the conduit.
(792) Embodiment 106. The method of any preceding embodiments 85 to 105, wherein the masking agent is added to at least a part of the porous section of the conduit from a masking agent solution.
(793) Embodiment 107. The method of embodiment 106, wherein the masking agent solution is a polymer solution.
(794) Embodiment 108. The method of embodiment 106 or embodiment 107, wherein the step of adding the masking agent to at least a part of the porous section of the conduit is performed by spraying the masking agent solution onto at least a part of the porous section of the conduit.
(795) Embodiment 109. The method of embodiment 108, wherein the masking agent solution is added to the conduit by spraying the masking agent onto at least a part of the inner surface of the wall of the conduit.
(796) Embodiment 110. The method of any one of embodiments 106 to embodiment 109, wherein the step of adding the masking agent to at least a part of the porous section of the conduit is performed by immersing at least a part of the porous section of the conduit in the masking agent solution.
(797) Embodiment 111. The method of embodiment 110, wherein substantially all of the conduit is immersed in the masking agent solution.
(798) Embodiment 112. The method of any one of embodiments 106 to 111, wherein the masking agent solution comprises between approximately 5% weight/volume (w/v) of polymer in solution and approximately 30% w/v of polymer in solution.
(799) Embodiment 113. The method of any preceding embodiments 85 to 112, wherein the step of adding the sealant to at least a part of the porous section of the conduit does not result in the removal of the masking agent from the porous section of the conduit.
(800) Embodiment 114. The method of any preceding embodiments 85 to 113, wherein the masking agent is configured to biodegrade when the vascular prosthesis is implanted inside the human or animal body.
(801) Embodiment 115. The method of any preceding embodiments 85 to 114, wherein the conduit is a woven fibrous polymer conduit.
(802) Embodiment 116. The method of any preceding embodiments 85 to 115, wherein the sealant comprises a polymer.
(803) Embodiment 117. The method of embodiment 116, wherein the sealant is a water-insoluble polymer.
(804) Embodiment 118. The method of any preceding embodiments 85 to 117, wherein the sealant forms a sealing layer when added to the conduit, the sealing layer being a polymer layer.
(805) Embodiment 119. The method of any one of embodiments 116 to 118, wherein the sealant comprises at least one of: silicone, room temperature vulcanising silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, and polycarbonate.
(806) Embodiment 120. The method of any preceding embodiments 85 to 119, wherein the sealant is added to the conduit from a sealant solution.
(807) Embodiment 121. The method of embodiment 120 wherein the sealant solution is a polymer solution.
(808) Embodiment 122. The method of embodiment 120 or embodiment 121, wherein the sealant solution comprises an organic solvent.
(809) Embodiment 123. The method of embodiment 122, wherein the sealant solution comprises at least one of heptane and xylene.
(810) Embodiment 124. The method of any preceding embodiments 85 to 123, wherein the sealant is added to at least a part of the porous section of the conduit by brushing and/or spraying the sealant thereon.
(811) Embodiment 125. The method of any preceding embodiments 85 to 124, wherein the sealant is configured to mitigate movement of blood through the wall of the conduit.
(812) Embodiment 126. The method of any preceding embodiments 85 to 125, comprising the further step of sterilising the vascular prosthesis.
(813) Embodiment 127. The method of embodiment 126, wherein the vascular prosthesis is sterilised by way of at least one of: a gamma sterilisation process, an electron beam sterilisation process, and an ethylene oxide sterilisation process.
(814) Embodiment 128. The method of any preceding embodiments 85 to 127, wherein the conduit is moveable between a contracted state and an extended state.
(815) Embodiment 129. The method of embodiment 128, wherein the step of adding the masking agent to at least a part of the porous section of the conduit is carried out, at least in part, while the conduit is in the contracted state, in the extended state, and/or when moved between the contracted state and the extended state.
(816) Embodiment 130. The method of embodiment 128 or embodiment 129, wherein the step of adding the sealant to at least a part of the porous section of the conduit is carried out, at least in part, while the conduit is in the contracted state, in the extended state, and/or when moved between the contracted state and the extended state.
(817) Embodiment 131. The method of any preceding embodiments 85 to 130, the method comprising one or more steps of weighing the conduit and/or measuring the length of the conduit, to determine, at least in part, the amount of masking agent, and/or or the amount of sealant, to add to at least a part of the porous section of the conduit.
(818) Embodiment 132. The method of any preceding embodiments 85 to 131, wherein the step of adding the masking agent to at least a part of the porous section of the conduit comprises the step of providing gas to the conduit.
(819) Embodiment 133. The method of embodiment 132, wherein the gas is directed towards the outer surface of the wall of the conduit.
(820) Embodiment 134. The method of embodiment 132 or embodiment 133, wherein the gas is air.
(821) Embodiment 135. The method of any preceding embodiments 85 to 134, wherein the method comprises the step of adding a support member to the conduit.
(822) Embodiment 136. The method of embodiment 135, wherein the support member is added to the outer surface of the wall of the conduit.
(823) Embodiment 137. The method of embodiment 136, wherein the support member is wrapped around the outer surface of the wall of the conduit.
(824) Embodiment 138. The method of embodiment 137, wherein the conduit comprises a plurality of crimps, and the support member is arranged to nest between the plurality of crimps.
(825) Embodiment 139. The method of any one of embodiments 135 to 138, wherein the step of adding the support member to the conduit is carried out prior to the step of adding the sealant to the conduit.
(826) Embodiment 140. The method of any one of embodiments 135 to 139, wherein the step of adding the sealant to the conduit is used, at least in part, to attach the support member to the conduit.
(827) Embodiment 141. The method of any one of embodiments 135 to 140, wherein the support member is a flexible, polymer member.
(828) Embodiment 142. The method of any preceding embodiments 85 to 141, wherein the method comprises one or more steps of selectively adding sealant to one or more sections of the conduit, such that the conduit comprises at least two sections comprising substantially different amounts of sealant thereon.
(829) Embodiment 143. A vascular prosthesis comprising:
(830) a conduit comprising a wall, the wall of the conduit comprising an inner surface and an outer surface, at least a section of the conduit being porous;
(831) wherein at least a part of the porous section comprises a sealant configured to mitigate movement of fluid through the wall of the conduit; and
(832) wherein the inner surface of the wall of the conduit is substantially devoid of the sealant.
(833) Embodiment 144. The vascular prosthesis of embodiment 143, wherein the sealant forms a sealing layer on at least a part of the outer surface of the wall of the conduit.
(834) Embodiment 145. The vascular prosthesis of embodiment 143 or embodiment 144, wherein the sealant forms a sealing layer on substantially all of the outer surface of the wall of the conduit.
(835) Embodiment 146. The vascular prosthesis of any one of embodiments 143 to 145, wherein substantially all of the conduit is porous.
(836) Embodiment 147. The vascular prosthesis of any one of embodiments 143 to 146, wherein the inner surface of the wall of the conduit is configured to promote the ingrowth of biological tissue thereon.
(837) Embodiment 148. The vascular prosthesis of any one of embodiments 143 to 147, wherein the conduit is a woven fibrous polymer conduit.
(838) Embodiment 149. The vascular prosthesis of any one of embodiments 143 to 148, wherein the sealant forms a sealing layer, the sealing layer being a polymer layer.
(839) Embodiment 150. The vascular prosthesis of any one of embodiments 143 to 149, wherein the sealant comprises at least one of: silicone, room temperature vulcanising silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, and polycarbonate.
(840) Embodiment 151. The vascular prosthesis of any one of embodiments 143 to 150, wherein the sealant is configured to mitigate movement of blood through the wall of the conduit.
(841) Embodiment 152. The vascular prosthesis of any one of embodiments 143 to 151, wherein the vascular prosthesis is sterilised.
(842) Embodiment 153. The vascular prosthesis of embodiment 152, wherein the vascular prosthesis is sterilised by way of at least one of the following: a gamma sterilisation process, an ethylene oxide sterilisation process, and an electron beam sterilisation process.
(843) Embodiment 154. The vascular prosthesis of any one of embodiments 143 to 153, wherein the conduit is moveable between a contracted state and an extended state.
(844) Embodiment 155. The vascular prosthesis of any one of embodiments 143 to 154, wherein the conduit comprises a support member.
(845) Embodiment 156. The vascular prosthesis of embodiment 155, wherein the support member is located substantially adjacent to the outer surface of the wall of the conduit.
(846) Embodiment 157. The vascular prosthesis of embodiment 156, wherein the support member is wrapped around the outer surface of the wall of the conduit.
(847) Embodiment 158. The vascular prosthesis of embodiment 157, wherein the conduit comprises a plurality of crimps, the support member being arranged to nest between the plurality of crimps.
(848) Embodiment 159. The vascular prosthesis of any one of embodiments 155 to 158, wherein the sealant is arranged to, at least in part, attach the support member to the conduit.
(849) Embodiment 160. The vascular prosthesis of any one of embodiments 155 to 159, wherein the support member is a flexible, polymer member.
(850) Embodiment 161. The vascular prosthesis of any one of embodiments 143 to 160, wherein the conduit is configured to have at least two sections having substantially different amounts of sealant thereon.
(851) Embodiment 162. A kit of parts for manufacturing a vascular prosthesis, the kit of parts comprising:
(852) (i) a conduit comprising a wall, the wall of the conduit comprising an inner surface and an outer surface, at least a section of the conduit being porous;
(853) (ii) a masking agent; and
(854) (iii) a sealant;
(855) when applied to at least a part of the porous section of the conduit, the masking agent being configured to mitigate presence of the sealant on the inner surface of the conduit; and when applied to at least a part of the porous section of the conduit, the sealant being configured to mitigate movement of fluid through the wall of the conduit.
(856) Embodiment 163. The kit of parts of embodiment 162, wherein addition of the sealant to at least a part of the porous section of the conduit forms a sealing layer on at least a part of the outer surface of the wall of the conduit.
(857) Embodiment 164. The kit of parts of embodiment 162 or embodiment 163, wherein addition of the masking agent to at least a part of the porous section of the conduit forms a masking agent layer on at least part of the inner surface of the wall of the conduit.
(858) Embodiment 165. The kit of parts of any one of embodiments 162 to 164, wherein substantially all of the conduit is porous.
(859) Embodiment 166. The kit of parts of any one of embodiments 162 to 165, the kit of parts comprising a masking agent remover, the masking agent remover being operable to remove applied masking agent from the conduit.
(860) Embodiment 167. The kit of parts of embodiment 166, wherein the masking agent remover comprises a solvent.
(861) Embodiment 168. The kit of parts of embodiment 167, wherein the solvent comprises water.
(862) Embodiment 169. The kit of parts of any one of embodiments 166 to 168, wherein the masking agent remover is operable to remove applied masking agent from the conduit at a temperature of between approximately 15° C. and approximately 140° C.
(863) Embodiment 170. The kit of parts of any one of embodiments 162 to 169, the kit of parts comprising an abrading tool, the abrading tool being operable to remove applied masking agent from the conduit.
(864) Embodiment 171. The kit of parts of any one of embodiments 162 to 170, wherein the inner surface of the wall of the conduit is configured to promote the ingrowth of biological tissue thereon.
(865) Embodiment 172. The kit of parts of any one of embodiments 162 to 171, wherein the masking agent comprises a polymer.
(866) Embodiment 173. The kit of parts of embodiment 172, wherein the masking agent comprises a water-soluble polymer.
(867) Embodiment 174. The kit of parts of any one of embodiments 162 to 173, wherein masking agent applied to the conduit forms a masking agent layer, the masking agent layer being a polymer layer.
(868) Embodiment 175. The kit of parts of any one of embodiments 172 to 174, wherein the masking agent comprises at least one of: polyvinylpyrrolidone, glycerol, methyl cellulose, and poly(ethylene glycol) hydrogel.
(869) Embodiment 176. The kit of parts of any one of embodiments 162 to 175, wherein the masking agent is biocompatible.
(870) Embodiment 177. The kit of parts of any one of embodiments 162 to 176, wherein masking agent applied to the conduit forms a biocompatible masking agent layer.
(871) Embodiment 178. The kit of parts of any one of embodiments 162 to 177, wherein the kit of parts comprises a masking agent solution, the masking agent solution being operable to apply masking agent to the conduit.
(872) Embodiment 179. The kit of parts of embodiment 178, wherein the masking agent solution is a polymer solution.
(873) Embodiment 180. The kit of parts of embodiment 178 or embodiment 179, wherein the conduit is immersible in the masking agent solution.
(874) Embodiment 181. The kit of parts of any one of embodiments 178 to 180, wherein the masking agent solution comprises between approximately 5% w/v of polymer in solution and approximately 30% w/v of polymer in solution.
(875) Embodiment 182. The kit of parts of any one of embodiments 162 to 181, wherein when the masking agent and the sealant are applied to the conduit, the sealant is configured such that addition of the sealant to the conduit does not result in the removal of the applied masking agent from the conduit.
(876) Embodiment 183. The kit of parts of any one of embodiments 162 to 182, wherein the masking agent is configured to biodegrade when implanted inside the human or animal body.
(877) Embodiment 184. The kit of parts of any one of embodiments 162 to 183, wherein the conduit is a woven fibrous polymer conduit.
(878) Embodiment 185. The kit of parts of any one of embodiments 162 to 184, wherein the sealant comprises a polymer, optionally a water-insoluble polymer.
(879) Embodiment 186. The kit of parts of any one of embodiments 162 to 185, wherein the sealant, when applied to the conduit, forms a sealing layer, the sealing layer being a polymer layer.
(880) Embodiment 187. The kit of parts of embodiment 185 or embodiment 186, wherein the sealant comprises at least one of: silicone, room temperature vulcanising silicone, thermoplastic polyurethane, aliphatic polycarbonate, one or more thermoplastic elastomers, and polycarbonate.
(881) Embodiment 188. The kit of parts of any one of embodiments 162 to 187, wherein the kit of parts comprises a sealant solution operable to apply sealant to the conduit.
(882) Embodiment 189. The kit of parts of embodiment 188, wherein the sealant solution is a polymer solution.
(883) Embodiment 190. The kit of parts of embodiment 188 or embodiment 189, wherein the sealant solution comprises an organic solvent.
(884) Embodiment 191. The kit of parts of embodiment 190, wherein the sealant solution comprises at least one of heptane and xylene.
(885) Embodiment 192. The kit of parts of any one of embodiments 162 to 191, the kit of parts comprising a sealant applicator operable to apply sealant to the conduit, and/or a masking agent applicator operable to apply masking agent to the conduit.
(886) Embodiment 193. The kit of parts of embodiment 192, wherein the sealant applicator is an apparatus for spray coating the sealant, and/or a brush, or the like.
(887) Embodiment 194. The kit of parts of embodiment 192 or embodiment 193, wherein the masking agent applicator is a brush, an apparatus for spray-coating the masking agent, an apparatus for dipping or immersing the conduit in the masking agent, and/or an apparatus for wiping the masking agent onto the conduit.
(888) Embodiment 195. The kit of parts of any one of embodiments 162 to 194, wherein the sealant, when applied to at least a part of the porous section of the conduit, is configured to mitigate movement of blood through the wall of the conduit.
(889) Embodiment 196. The kit of parts of any one of embodiments 162 to 195, wherein the conduit is moveable between a contracted state and an extended state.
(890) Embodiment 197. The kit of parts of any one of embodiments 162 to 196, the kit of parts comprising a further prosthesis.
(891) Embodiment 198. The kit of parts of embodiment 197, wherein the further prosthesis is at least one of: a biological heart valve, a synthetic heart valve, a cardiac assist device, and a ventricular assist device, or the like.
(892) Embodiment 199. The kit of parts of any one of embodiments 162 to 198, the kit of parts comprising a weighing device and/or a device for measuring the length of the conduit.
(893) Embodiment 200. The kit of parts of any one of embodiments 162 to 199, the kit of parts comprising a gas flow apparatus operable to provide gas flow to the conduit.
(894) Embodiment 201. The kit of parts of embodiment 200, wherein the gas is air.
(895) Embodiment 202. A vascular system, the vascular system comprising:
(896) a vascular prosthesis manufactured according to any one of embodiments 85 to 142; and
(897) a further prosthesis;
(898) wherein the vascular prosthesis is connected to the further prosthesis, such that fluid can flow between the vascular prosthesis and the further prosthesis.
(899) Embodiment 203. The vascular system of embodiment 202, wherein the further prosthesis is at least one of: a biological heart valve, a synthetic heart valve, a cardiac assist device, and a ventricular assist device, or the like.
(900) Embodiment 204. A method of implanting a vascular prosthesis, the method comprising the steps of:
(901) providing a vascular prosthesis manufactured using the method of any one of embodiments 85 to 142;
(902) connecting an inlet of the vascular prosthesis to a first blood vessel; and
(903) connecting an outlet of the vascular prosthesis to a second blood vessel;
(904) such that blood can flow between the first and second blood vessels through the vascular prosthesis.
(905) Embodiment 205. The method of embodiment 204, wherein the first and second blood vessels are formed from a blood vessel which is diseased, or has been severed, bisected, or the like.
(906) Embodiment 206. A method of implanting a vascular prosthesis, the method comprising the steps of:
(907) providing a vascular prosthesis according to any one of embodiments 143 to 161;
(908) connecting the vascular prosthesis to a first blood vessel; and
(909) connecting the vascular prosthesis to a second blood vessel;
(910) such that blood can flow between the first and second blood vessels through the vascular prosthesis.
(911) Embodiment 207. The method of embodiment 206, wherein the first and second blood vessels are formed from a blood vessel which is diseased, or has been severed, bisected, or the like.
(912) Embodiment 207. A method of implanting a vascular system, the method comprising the steps of:
(913) providing a vascular system, the vascular system comprising:
(914) a vascular prosthesis manufactured according to any one of embodiments 85 to 142; and
(915) a further prosthesis;
(916) wherein the vascular prosthesis is connectable to the further prosthesis;
(917) connecting the vascular prosthesis to the further prosthesis, such that blood can flow therebetween;
(918) connecting an end of a blood vessel to the vascular prosthesis; and
(919) connecting the further prosthesis to the heart;
(920) such that blood can flow between the blood vessel and the heart through the vascular system.
(921) Embodiment 209. The method of embodiment 208, wherein the further prosthesis is at least one of: a biological heart valve, a synthetic heart valve, a cardiac assist device, and a ventricular assist device, or the like.
(922) Embodiment 210. A method for manufacturing a substantially impermeable textile graft comprising:
(923) providing a textile graft having a first surface and an opposed second surface;
(924) providing a water soluble masking agent comprising polyvinylpyrrolidone and glycerol without mixing or combining the polyvinylpyrrolidone and the glycerol with added water;
(925) applying the water soluble masking agent to a portion of the first surface of the textile graft;
(926) providing a water insoluble sealing agent;
(927) maintaining the second surface of the textile graft receptive for receiving the water insoluble sealing agent; and
(928) applying the water insoluble sealing agent to the second surface of the textile graft.
(929) Embodiment 211. The method of embodiment 210, wherein the water soluble masking agent consists essentially of polyvinylpyrrolidone and glycerol.
(930) Embodiment 212. The method of any previous embodiments starting with 210, wherein the water soluble masking agent comprises from about 25% w/w of the polyvinylpyrrolidone in the glycerol to about 75% w/w of the polyvinylpyrrolidone in glycerol.
(931) Embodiment 213. The method of any previous embodiments starting with 210, wherein the water soluble masking agent is flowable.
(932) Embodiment 214. The method of any previous embodiments starting with 210, wherein the water soluble masking agent is prepared by dissolving the polyvinylpyrrolidone in the glycerol.
(933) Embodiment 215. The method of any previous embodiments starting with 210, wherein the polyvinylpyrrolidone is dissolved into the glycerol with one or more of stirring and application of heat.
(934) Embodiment 216. The method of any previous embodiments starting with 210, wherein the step of maintaining the second surface of the textile graft receptive for receiving the water insoluble sealing agent comprises preventing egress of the water soluble masking agent from the first surface to the second surface.
(935) Embodiment 217. The method of any previous embodiments starting with 210, wherein the step of preventing the egress of the water soluble masking agent from the first surface to the second surface comprises substantially prohibiting wicking of the water soluble masking agent from the first surface to the second surface.
(936) Embodiment 218. The method of any previous embodiments starting with 210, wherein the step of maintaining the second surface of the textile graft receptive for receiving the water insoluble sealing agent comprises removal of the water soluble masking agent from the second surface.
(937) Embodiment 219. The method of any previous embodiments starting with 210, wherein the step of removal of the water soluble masking agent from the second surface comprises dissolving the water soluble masking agent from the second surface.
(938) Embodiment 220. The method of any previous embodiments starting with 210, wherein the step of removal of the water soluble masking agent from the second surface comprises ablating the water soluble masking agent from the second surface.
(939) Embodiment 221. The method of any previous embodiments starting with 210, wherein the polyvinylpyrrolidone has a molecular weight of from about 2,500 g/mol to about 55,000 g/mol.
(940) Embodiment 222. The method of any previous embodiments starting with 210, wherein the water insoluble sealing agent comprises a material selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof.
(941) Embodiment 223 The method of any previous embodiments starting with 210, wherein the step of applying the water insoluble sealing agent to the second surface of the textile graft comprises spraying water insoluble sealing agent onto the second surface of the textile graft.
(942) Embodiment 224. The method of any previous embodiments starting with 210, wherein the spraying is forced air spraying or ultrasonic spraying.
(943) Embodiment 225. The method of any previous embodiments starting with 210, further comprising removing the water soluble masking agent after the step of applying the water insoluble sealing agent.
(944) Embodiment 226. The method of any previous embodiments starting with 210, further comprising curing the water insoluble sealing agent.
(945) Embodiment 227 The method of any previous embodiments starting with 210, wherein, after curing of the water insoluble sealing agent, the textile graft is substantially impermeable to liquid.
(946) Embodiment 228. The method of any previous embodiments starting with 210, wherein, after curing of the water insoluble sealing agent, the textile graft has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(947) Embodiment 229. The method of any previous embodiments starting with 210, wherein the textile graft is a tubular textile graft.
(948) Embodiment 230. The method of any previous embodiments starting with 210, wherein the water soluble masking agent has a viscosity from about 2,000 centipoise at room temperature to about 100,000 centipoise at room temperature.
(949) Embodiment 231. The method of any previous embodiments starting with 210, wherein the water soluble masking agent has a viscosity from about 50,000 centipoise at room temperature to about 100,000 centipoise at room temperature.
(950) Embodiment 232. A method for manufacturing a substantially impermeable textile graft comprising:
(951) providing a textile graft having a first surface and an opposed second surface;
(952) providing a water soluble masking agent selected from the group consisting of polyvinylpyrrolidone, glycerol, methyl cellulose, poly(ethylene glycol), poly(ethylene glycol) hydrogel, polyethylene oxide, and combinations thereof;
(953) applying the water soluble masking agent to a portion of the first surface of the textile graft, wherein a portion of the water insoluble sealing agent is optionally disposed on the second surface of the textile graft;
(954) ablating a portion of the water soluble masking agent from the second surface of the textile graft;
(955) providing a water insoluble sealing agent selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof; and
(956) applying the water insoluble sealing agent to the second surface of the textile graft.
(957) Embodiment 233. The method of embodiment 232, wherein the step of ablating further comprises providing a flow of solid particulates against the second surface of the textile graft.
(958) Embodiment 234. The method of any previous embodiments starting with 232, wherein the solid particulates are a material selected from the group consisting of sodium bicarbonate, sodium chloride, sugar, magnesium sulphate, potassium chloride, and combinations thereof.
(959) Embodiment 235. The method of any previous embodiments starting with 232, wherein the solid particulates have an average particle size across their largest dimension from about 50 microns to about 300 microns.
(960) Embodiment 236. The method of any previous embodiments starting with 232, wherein the solid particulates have a Moh's hardness from about 1 to about 4.
(961) Embodiment 237. The method of any previous embodiments starting with 232, wherein the solid particulates are sprayed at a pressure from about 10 psig to about 50 psig.
(962) Embodiment 238. The method of any previous embodiments starting with 232, further comprising curing the water insoluble sealing agent.
(963) Embodiment 239. The method of any previous embodiments starting with 232, wherein, after curing of the water insoluble sealing agent, the textile graft is substantially impermeable to liquid.
(964) Embodiment 240. The method of any previous embodiments starting with 232, wherein, after curing of the water insoluble sealing agent, the textile graft has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(965) Embodiment 241. The method of any previous embodiments starting with 232, further comprising removing the water soluble masking agent after the step of applying the water insoluble sealing agent.
(966) Embodiment 240. The method of any previous embodiments starting with 232, further comprising adding a dye to the water insoluble sealing agent.
(967) Embodiment 241. The method of any previous embodiments starting with 232, further comprising adding a dye to the water soluble masking agent.
(968) Embodiment 242. A textile graft made by the method of any of the embodiments 210-231.
(969) Embodiment 243. A textile graft made by the method of any of the embodiments 232-241.
(970) Embodiment 244. A method of providing a sealant to a textile graft comprising:
(971) providing a textile graft having a first surface and an opposed second surface and having a textile pattern of yarns inter-engaging yarns and interstices between or in the yarns;
(972) providing a water soluble masking agent selected from the group consisting of polyvinylpyrrolidone, glycerol, methyl cellulose, poly(ethylene glycol), poly(ethylene glycol) hydrogel, polyethylene oxide, and combinations thereof;
(973) applying the water soluble masking agent to at least a portion of the first surface of the textile graft, wherein a portion of the water soluble masking agent is further disposed at a plurality of the interstices;
(974) providing a water insoluble sealing agent selected from the group consisting of silicones, polyurethanes, polycarbonates, thermoplastic elastomers, and combinations thereof; and
(975) applying the water insoluble sealing agent to the second surface of the textile graft and over the portion of the water soluble masking agent being disposed at a plurality of the interstices;
(976) whereby the water insoluble sealing agent spreads over the water soluble masking agent to provide one or more of the following: a substantially homogenous layer of the water insoluble sealing agent; a substantially uniform and uninterrupted coating of the water insoluble sealing agent; a layer of water insoluble sealing agent having a substantially uniform weight per given area of application; a substantially liquid impermeable barrier to the underlying textile graft surface; a substantially lower force to extend a graft coated with the water insoluble sealing agent as compared to comparable grafts which have not used a masking agent; a substantially less amount of water insoluble sealing agent to provide a substantially liquid impermeable barrier to the underlying textile graft surface as compared to comparable grafts which have not used a masking agent; and combinations thereof.
(977) Embodiment 245. The method of embodiment 244, further comprising removing the water soluble masking agent after the step of applying the water insoluble sealing agent.
(978) Embodiment 246. The method of any previous embodiments starting with 244, further comprising curing the water insoluble sealing agent.
(979) Embodiment 247. The method of any previous embodiments starting with 244, wherein, after curing of the water insoluble sealing agent, the water insoluble sealing agent is disposed over the interstices between and in the yarns.
(980) Embodiment 248. The method of any previous embodiments starting with 244, wherein, the textile graft is substantially impermeable to liquid.
(981) Embodiment 249. The method of any previous embodiments starting with 244, wherein, after curing of the water insoluble sealing agent, the textile graft has a water permeability of about 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure or less than 0.16 ml/min/cm.sup.2 at 120 mm Hg pressure.
(982) Embodiment 250. A textile graft made by the method of any of the embodiments 244-249.
(983) Embodiment 251. A method of sealing a textile graft comprising:
(984) applying a coating of a substantially water soluble masking agent, having a viscosity of from about 2,000 centipoise at room temperature to about 100,000 centipoise at room temperature, to at least a portion of a luminal surface of the textile graft, wherein a portion of the water soluble masking agent is further disposed at a plurality of interstices in the graft; and
(985) applying a water insoluble sealing agent to an outer graft surface opposing the luminal surface of the graft;
(986) wherein the water soluble masking agent causes one or more of the following to occur:
(987) a substantially homogenous layer of the water insoluble sealing agent is formed; a substantially uniform and uninterrupted coating of the water insoluble sealing agent is formed; a layer of water insoluble sealing agent having a substantially uniform weight per given area of application; a substantially liquid impermeable barrier to the underlying textile graft surface; a substantially lower force to extend a graft coated with the water insoluble sealing agent as compared to comparable grafts which have not used a masking agent; a substantially less amount of water insoluble sealing agent to provide a substantially liquid impermeable barrier to the underlying textile graft surface as compared to comparable grafts which have not used a masking agent; and combinations thereof.
(988) Embodiment 252. The method of any of the embodiments claims 210 to 231, wherein the steps of applying the water soluble masking agent and applying the water insoluble sealing agent are performed substantially concurrently.
(989) Embodiment 253. The method of embodiment 252, wherein the step of applying the water soluble masking agent further comprises applying heat, directly or indirectly, to the water soluble masking agent.
(990) Embodiment 254. The method of embodiment 253, wherein the step of applying water insoluble sealing agent further comprises applying cooling, directly or indirectly, to the second surface of the textile graft.
(991) Embodiment 255. The method of any of the embodiments claims 210 to 231, further comprising:
(992) controlling temperature of the water soluble masking agent while apply the water soluble masking agent to the first surface of the textile graft to control flow of the water soluble masking agent at the first surface of the textile graft; and
(993) controlling temperature at or near the second surface of the textile graft while apply the water soluble masking agent to the first surface of the textile graft to control the flow of the water soluble masking agent towards the second surface of the textile graft.
(994) Embodiment 256. The method of claim 255, wherein the step of controlling the temperature at or near the second textile surface is performed prior to the step of applying the water insoluble sealing agent to the second surface of the textile graft.
(995) Embodiment 257. The method of claim 255, wherein the step of controlling the temperature at or near the second textile surface is performed during the step of applying the water insoluble sealing agent to the second surface of the textile graft.
(996) Embodiment 258. The method of claim 255, wherein the step of controlling the temperature at or near the second textile surface is performed prior the step of applying the water insoluble sealing agent to the second surface of the textile graft and during the step of applying the water insoluble sealing agent to the second surface of the textile graft.