Electrospun Suture Ring

Abstract

A medical implant is provided defined as an electrospun hollow-cored porous suture ring. The suture ring is a continuous ring made by rolling up circular sheet of electrospun material, which was electrospun over a cylindrical target. The suture ring, upon implantation, is capable of being absorbed and replaced by natural tissue due to ingrowth of cells and nutrients into pores of the electrospun hollow-cored biodegradable suture ring. The suture ring addresses at least some of the existing problems with suture or sewing rings.

Claims

1. A medical implant, comprising: an electrospun hollow-cored porous suture ring defining a hollow-core diameter, a wall thickness and an overall ring diameter, wherein the electrospun hollow-cored porous suture ring is a continuous ring being a rolled-up circular sheet of electrospun material rolled up over the longitudinal axis of the circular sheet.

2. The medical implant as set forth in claim 1, wherein the electrospun hollow-cored porous suture ring having a pore size distribution of 5 to 50 micrometers.

3. The medical implant as set forth in claim 1, wherein the electrospun hollow-cored porous suture ring is bioabsorbable and therewith capable of being absorbed and replaced by natural tissue due to ingrowth of cells and nutrients into pores of the electrospun hollow-cored biodegradable suture ring.

4. The medical implant as set forth in claim 1, further comprising a heart valve leaflet and wherein the electrospun hollow-cored porous suture ring is attached to the heart leaflet.

5. The medical implant as set forth in claim 1, wherein the hollow core diameter is between 0.1-3 millimeters.

6. The medical implant as set forth in claim 1, wherein the wall thickness is between 100-1000 micrometers.

7. The medical implant as set forth in claim 1, wherein the overall inner ring diameter is between 10-22 millimeters.

8. The medical implant as set forth in claim 1, wherein the overall inner ring diameter is between 18-28 millimeters.

9. The medical implant as set forth in claim 1, wherein the overall inner ring diameter is between 25-40 millimeters.

10. A method of making a medical implant, comprising: (a) electrospinning a polymer coating on a cylindrical target forming a cylindrical electrospun sheet, whereby the cylindrical target defines a longitudinal axis; (b) rolling up the cylindrical electrospun sheet over the longitudinal axis into a ring; and (c) removing the rolled-up ring from the cylindrical target resulting in an electrospun hollow-cored suture ring defining a hollow-core diameter, a wall thickness and an overall ring diameter.

11. The method as set forth in claim 10, further comprising forming a sacrificial electrospun circular sheet, wherein the hollow-core is formed by the step of rolling up the sacrificial electrospun circular sheet and then removing the sacrificial electrospun circular sheet.

12. The method as set forth in claim 11, wherein the removing is by using a solvent resulting in the hollow core.

13. A method of making a medical implant, comprising: (a) rolling up a first polymer sheet on a cylindrical target; (b) rolling up a second polymer sheet on the cylindrical target over the rolled up first polymer sheet; and (c) dissolving the first polymer sheet from the second polymer sheet resulting in a hollow-cored ring defining a hollow-core diameter, a wall thickness and an overall ring diameter.

14. The method as set forth in claim 13, wherein the dissolving is by using water.

15. The method as set forth in claim 13, wherein the first polymer sheet is an electrospun polymer sheet.

16. The method as set forth in claim 13, wherein the second polymer sheet is an electrospun polymer sheet.

17. The method as set forth in claim 13, wherein the medical implant is a suture ring.

18. The method as set forth in claim 13, wherein the medical implant further comprises a heart valve leaflet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 shows 100 according to an exemplary embodiment of an existing sewing ring 120 being a silicon ring covered with synthetic fabric.

[0023] FIG. 2 shows according to an exemplary embodiment of the invention a production method for making a hollow-cored porous suture ring using electrospinning. A longitudinal axis is defined in aspect D which defines the longitudinal axis. When the method is completed, the electrospun hollow-cored porous suture ring is a continuous ring being a rolled-up circular sheet of electrospun material rolled up over the longitudinal axis of the circular sheet.

[0024] FIG. 3 shows 300 according to an exemplary embodiment of the invention a hollow-cored porous suture ring 310 with thickness of hollow core and wall of the ring—half a ring cut crosswise.

[0025] FIG. 4 shows 400 according to an exemplary embodiment of the invention a surgical valve with the leaflet material 410 and the hollow-cored porous suture ring 420.

DETAILED DESCRIPTION

[0026] Pure polymer valves may overcome the problems in the art related to the use of animal-derived tissue. In this context, pure is defined or understood as free of animal derived tissue. Besides improving manufacturability and solving current issues with animal tissue sourcing, pure polymer valves also avoid the need for glutaraldehyde treatment and rinsing, potentially reducing calcification and improving long term durability. Therefore, one embodiment of the invention is a heart valve where the leaflets are composed of a polymer material, preferably that enable ETR. In addition, this invention provides heart valves where the leaflets are made of bioabsorbable supramolecular polymers, preferably that enable ETR.

[0027] In another embodiment, the invention is a suture ring for the heart valve. The suture ring is electrospun from a polymer material defined infra, and preferably bioabsorbable. A new production method has been developed to create this electrospun sewing ring according to steps A-E and G (FIG. 2): [0028] A. A solvable polymer coating 210 is spun on a cylindrical target 220. [0029] B. The solvable polymer coating is rolled-up 230 on the target until it forms a ring. [0030] C. Polymer 250 is spun as a coating over the solvable polymer ring 240 and over the cylindrical target 220. [0031] D. The polymer scaffold is rolled-up over the solvable polymer ring as shown by 260 and over the longitudinal axis (straight arrow), thus forming a ring with an inner solvable polymer and an outer shell of the polymer. [0032] E. The ring is removed from the target by rolling of as shown by 270. [0033] F. Cross section of ring before dissolving solvable polymer in water. [0034] G. The inner solvable polymer ring is dissolved in water overnight as shown by 280. [0035] H. Cross section of the hollow polymer ring (290 indicates hollow space).

[0036] Based on this method, a suture ring is produced that has the form of a hollow closed ring made out of electrospun fibers from the polymer (FIG. 3). The hollow feature is the crux of the invention and makes the ring flexible. Surgeons would be easily able to place sutures in the electrospun sewing ring. FIG. 4 shows a workable example of a surgical valve with an electrospun polymer hollow sewing ring attached to it.

Exemplary Technical Specifications of Hollow Polymer Sewing Ring

[0037] 1. Wall thickness: 100-1000 micrometers (in particular 200-500 micrometers), but not limited to this range (FIG. 3). [0038] 2. Hollow core diameter: 0.1-3 millimeters (in particular 1-3 mm) (FIG. 3). [0039] 3. Typical sizes for suture rings can be spun using different diameter in targets are application dependent and can range from 10-22 millimeters, 18-23 millimeters, or 25-40 millimeters (in particular 23 mm, 24 mm, 25 mm and 26 mm are preferred). Note this is the overall inner diameter of the suture ring. [0040] 4. The porous suture ring has a pore size distribution of 5 to 50 micrometers.

[0041] The hollow-cored porous suture ring should be flexible enough and not too rigid so that surgeons can easily go through with a needle and suture. It is desirable to have a stiffness in the same range or superior to state-of-the-art suture rings. Leakage volume and regurgitate fraction in hydrodynamic tests should be in the same range or superior to competitive surgical valves on the market.

[0042] Based on a touch and feel test of surgeons in the field, a wall thickness of 350 micrometers and a hollow core of 2 millimeters diameter was experienced positive on stiffness and flexibility. Thus, the wall thickness of the hollow polymer ring should not be too thick, but also not too thin. As an assumption, a minimum of 100 micrometers and a maximum of 1000 micrometers on wall thickness will give the correct stiffness and a hollow core of 0.1-3 millimeters diameter will contribute to the flexibility.

Definition of Polymer for the Embodiments in this Invention

[0043] The supramolecular polymer referenced herein may include:

the ureido-pyrimidinone (UPy) quadruple hydrogen-bonding motif (pioneered by Sijbesma (1997), Science 278, 1601-1604) and a polymer backbone, for example selected from the group of biodegradable polyesters, polyurethanes, polycarbonates, poly(orthoesters), polyphosphoesters, polyanhydrides, polyphosphazenes, polyhydroxyalkanoates, polyvinylalcohol, polypropylenefumarate. Examples of polyesters are polycaprolactone, poly(L-lactide), poly(DL-lactide), poly(valerolactone), polyglycolide, polydioxanone, and their copolyesters. Examples of polycarbonates are poly(trimethylenecarbonate), poly(dimethyltrimethylenecarbonate), poly(hexamethylene carbonate).

[0044] The same result may be obtained with alternative, non-supramolecular polymers, if properties are carefully selected and material processed to ensure required characteristics. These polymers may comprise biodegradable or non-biodegradable polyesters, polyurethanes, polycarbonates, poly(orthoesters), polyphosphoesters, polyanhydrides, polyphosphazenes, polyhydroxyalkanoates, polyvinylalcohol, polypropylenefumarate. Examples of polyesters are polycaprolactone, poly(L-lactide), poly(DL-lactide), poly(valerolactone), polyglycolide, polydioxanone, and their copolyesters. Examples of polycarbonates are poly(trimethylenecarbonate), poly(dimethyltrimethylenecarbonate), poly(hexamethylene carbonate).