BRAIDED SUPPORT STRUCTURE

Abstract

A braided support structure that folds upon release from a delivery device wherein said fold is at least partially effected by varying the pic angle of the braids at locations where the folding is desired.

Claims

1. A braided tubular medical implant comprising: a braided tubular structure having a first configuration and a second configuration wherein the first configuration is an elongated, unfolded configuration and the second configuration is a deployed, folded configuration; wherein said braided tubular structure includes: at least one circumferential preformed fold area having a first braid angle measured against a longitudinal axis; at least one body area adjacent said circumferential preformed fold area having a second braid angle measured against a longitudinal axis; wherein said first braid angle is not equal to said second braid angle.

2. The braided tubular medical implant of claim 1 wherein said second braid angle is greater than said first braid angle.

3. The braided tubular medical implant of claim 1 wherein said second braid angle is greater than 45 degrees and said first braid angle is less than 45 degrees.

4. A braided tubular support structure comprising: a first end; a second end; a first portion having a first braid angle; a second portion having a second braid angle; wherein locations of said first portion and said second portion are selected to effect a folding of said braided tubular support structure along a desired fold line when released from a delivery catheter.

5. The braided tubular medical implant of claim 4 wherein said second braid angle is greater than said first braid angle.

6. The braided tubular medical implant of claim 4 wherein said second braid angle is greater than 45 degrees and said first braid angle is less than 45 degrees.

7. A method of creating a braided tubular structure comprising: braiding at least one wire to form a tubular structure; heat setting the tubular structure such that braids resulting from said braiding are deformed to have peaks and valleys that correspond to the intersections of the braids; changing a pic angle of a section of said tubular structure by moving said peaks from an existing valley on which the peaks were formed during the heat setting to an adjacent valley.

8. The method of claim 7 wherein changing a pic angle of a section of said tubular structure by moving said peaks from an existing valley on which the peaks were formed during the heat setting to an adjacent valley results in the formation of a first section having a first braid angle and at least a second section having a second braid angle.

9. The method of claim 8 wherein said second braid angle is greater than said first braid angle.

10. The method of claim 8 wherein said second braid angle is greater than 45 degrees and said first braid angle is less than 45 degrees.

11. The method of claim 7 further comprising creating a fold line by folding said tubular structure circumferentially.

12. The method of claim 11 further comprising heat setting said fold line.

13. The method of claim 11 wherein creating a fold line comprises creating a fold line located at a location that corresponds to a pic angle that promotes ease of folding.

14. The method of claim 7 wherein braiding at least one wire to form a tubular structure comprises braiding at least one Nitinol wire to form a tubular structure.

15. The method of claim 7 wherein braiding at least one wire to form a tubular structure comprises braiding a plurality of wires to form a tubular structure.

16. A method of creating a braided tubular structure comprising: braiding at least one wire around a first length of a mandrel at a first pic angle; braiding said at least one wire around a second length of said mandrel at a second pic angle; wherein said first length of said mandrel is adjacent to said second length of said mandrel.

17. The method of claim 16 wherein said first length and said second length of said mandrel are separated by a feature usable to change the pic angle.

18. The method of claim 17 wherein said feature comprises pins radiating from said mandrel.

19. The method of claim 16 wherein said second braid angle is greater than said first braid angle.

20. The method of claim 16 wherein said second braid angle is greater than 45 degrees and said first braid angle is less than 45 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which:

[0015] FIG. 1A is a braid that has a pic angle that is larger than 45;

[0016] FIG. 1B is a braid that has a pic angle that is less than 45 degrees;

[0017] FIG. 1C is a braid that has a pic angle that is 45 degrees;

[0018] FIG. 2 is an embodiment of the invention in a folded configuration;

[0019] FIG. 3 is an embodiment of the invention exiting a delivery device;

[0020] FIG. 4 is a close-up view of an embodiment of an intersection of two filaments of a braid of the invention; and

[0021] FIG. 5 is a plan view of a braided device having regions of varying pic angles.

DESCRIPTION OF EMBODIMENTS

[0022] Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.

[0023] FIG. 1A, FIG. 1B and FIG. 1C comprise a chart showing braids with three general categories of pic angles and is shown for purposes of convention. Pic angle is being measured against a longitudinal axis of the braided device, which is shown as a horizontal axis line in FIG. 1A, FIG. 1B and FIG. 1C. The pic angle in FIG. 1A (“pic angle A”) is larger than 45 degrees. A braid having pic angle A exhibits radial stiffness and axial compliance.

[0024] The braid shown in FIG. 1B has a pic angle that is less than 45 degrees. A braid having pic angle B exhibits radial compliance and is axially stiff. Axial stiffness results in a resistance to folding due to the increased spacing density of the wires circumferentially. Additionally, as the pic angle decreases, folds involve bending the wires rather than rolling the wires over each other in the braid. This can be easily envisioned if one pictures a tube of longitudinally-aligned wires, thus having a pic angle of 0. To fold this tube, each wire would have to bend 180 degrees. Conversely, a tube formed of wires that are nearly circumferentially oriented, or having a pic angle close to 90 degrees, would fold easily as the wires would have to bend very little.

[0025] The braid of FIG. 1C has a pic angle that is 45 degrees. It is provided as an example of braid that is axially and radially neutral.

[0026] FIG. 2 shows an embodiment of a device 1 of the invention in a folded state. The device 1 has two folds, fold 10 and fold 11. The folds are separated by unfolded areas, such as area 12.

[0027] During loading into a delivery catheter, the device 1 is collapsed into an unfolded, elongated cylinder. Elongating the device 1 stretches the braids such that the wires move relative to each other and the pic angles all tend toward a shallower state. This change in pic angle is referred to herein as “compressive deformation.” Compressive deformation during loading will cause a pic angle A to tend toward a neutral pic angle C, and a pic angle C toward a pic angle B.

[0028] For example, if in a relaxed state the tubular structure 1 has a pic angle C of 45 degrees, then as the tubular structure is compressed, the pic angle will decrease to less than 45 degrees and will thus fall into the category of pic angle B. Conversely, if the tubular structure is expanded, the pic angle will increase to greater than 45 degrees and will thus fall into the category of pic angle A.

[0029] If this compression did not occur, the structure's wires within the braid would undergo a significant amount of bending to accommodate the folding process, which would take more force. Thus, to promote the folding process the area adjacent to the folds 10 and 11, such as area 13 in FIG. 3, would preferably have a pic angle A.

[0030] In locations that encounter axial loads once deployed, such as those placed on the device by blood flow, or in areas where minimal deformation is desired, a shallow pic angle B is used to promote axial stiffness. For example, referring to FIG. 2, location 12 would benefit from a pic angle B such that interactions and pressures from blood flow do not cause compressive motion within the layer. Similarly, location 14 in FIG. 3 would benefit from pic angle B in order to promote a ridged axial reference during the folding process of the implant.

[0031] For purposes of folding, such as at locations 10 and 11 of FIG. 2, it has been found that a pic angle of about 60 degrees or greater will effect the fold. Recall that, as stated above, increasing the radius of the tubular structure will increase the pic angle. It follows that as the tubular structure expands, areas of the tubular structure that achieve a pic angle of about 60 degrees first, will begin to invert or fold in on themselves.

[0032] Variances in pic angle are not simply a result of selective expansion and compression of the tubular structure. The variances are specifically woven into the braid. The process of acute braid angle change can be applied during the braiding process by providing features, such as pins, on the braiding mandrels used to create the braid that the wire being braided can be bent around to change the pic angle. Alternatively, the variances in pic angle can be achieved by manually moving the individual wires within the braid after the braid has been heat set.

[0033] For example, heat setting the braid causes deformation of the wires against each other, which forms peaks and valleys to form in the wires. In other words, if the wires are woven together and then unwoven, the wires will remain relatively straight. However, during the process of heat setting, each wire is deformed against the intersecting wires to form peaks and valleys that correspond to the intersections.

[0034] Referring to FIG. 4, it has been found that these peaks 22 and valleys 24 can be used to change pic angle. By manually moving a peak 22a from a corresponding valley 24a to an adjacent valley 24b, as shown by the arrow 26, the interference between the peaks and valleys will prevent the displaced peak 22a from returning to the original valley 24a. This results in a change of pic angle.

[0035] FIG. 5 shows a device 1 having regions 30, 32 and 34 having different pic angles. These regions may be formed by either providing features in the braiding mandrels during the original weaving process, or by using the peak and valley displacement method discussed above.

[0036] Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.