Method of Making a Highly Flexible Stent Graft and Stent Graft

Abstract

The present invention relates to a method of making a highly flexible stent graft (100), the method comprising: providing a stent graft having a first and a second longitudinal end and a lumen extending longitudinally therethrough, the stent graft comprising a base stent (10), the base stent having a first covering material (14) provided on the inside of the base stent so as to line the lumen and a second covering material (12) provided on the outside of the base stent, locally ablating the second covering material without puncturing the first covering material to thereby increase the flexibility of the stent graft.

Claims

1. A method of making a highly flexible stent graft, the method comprising: providing a stent graft having a first and a second longitudinal end and a lumen extending longitudinally therethrough, the stent graft comprising a base stent, the base stent having a first covering material provided on the inside of the base stent so as to line the lumen and a second covering material provided on the outside of the base stent, locally ablating the second covering material without puncturing the first covering material to thereby increase the flexibility of the stent graft, wherein the local ablation optionally occurs by means of applying heat to the second covering material.

2. The method according to claim 1, wherein the second covering material is ablated so as to locally uncover the base stent.

3. Method The method according to claim 1, wherein the second covering material is ablated so as to be locally thinned without locally uncovering the base stent.

4. The method according to claim 1, wherein the second covering material has, prior to the ablation, a thickness within the range of 0.02 to 0.15 mm.

5. The method according to claim 3, wherein the second covering material is locally thinned by at least 50% of the maximum thickness of the second covering material.

6. The method according to claim 1, wherein the heat is applied by means of a laser.

7. The method according to claim 6, wherein the laser is applied so as to graze the stent graft.

8. The method according to claim 6, wherein the laser is applied so as to impinge perpendicularly onto the second covering material.

9. The method according to claim 6, wherein the laser is applied so as to impinge at an angle between 30° and 60° onto the second covering material.

10. The method according to claim 1, the second covering material being ablated so as to cut a helical pattern into the second covering material, with the helix extending along the axial direction of the stent graft.

11. A stent graft for use in endovascular surgery, comprising: a base stent, the base stent having a proximal and a distal end and having a lumen extending longitudinally therethrough, a first covering material provided on the inside of the base stent so as to line the lumen, a second covering material provided on the outside of the base stent, the second covering material provided only on parts of the outside of the base stent so as to form a helical structure, the stent graft preferably having been manufactured using the method of one of the preceding claims.

12. The stent graft according to claim 11, further comprising an uncovered ring portion at one or both longitudinal ends of the base stent.

13. The stent graft according to claim 12, wherein the uncovered ring portion is positioned at both longitudinal ends of the base stent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a manufactured stent graft according to one embodiment of the present invention.

[0035] FIG. 2 shows a method of manufacturing a stent graft according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0036] A method of manufacturing a stent graft according to the present invention will now be described with reference to FIGS. 1 and 2.

[0037] In a first step (Step S100), an assembly mandrel 16 is provided. On that assembly mandrel 16, a first covering material 14, which could be ePTFE, is arranged. This ePTFE material can be provided in a sheet form. A sheet form, rather than a strip form, is advantageous in that no winding process is required: a winding process would require a great degree of precision since one has to ensure that adjacent windings abut against each other on the mandrel without overlapping in the radial direction. It is also possible to use a prefabricated tubular material instead of a sheet or a strip material.

[0038] Subsequently (Step S102), a base stent 10 is arranged on the first covering material 14. In that step, it is important to ensure that the base stent 10 retains its shape and is thus not stretched or otherwise deformed. The base stent 10 can be made of self-expanding material, such as nitinol, such that the base stent self-expands at around body temperature after being navigated to the desired location and deployed from the delivery catheter.

[0039] Subsequently, in step S104, a second covering material 12 is arranged on the base stent 10. The second covering material 12 could also be ePTFE that is provided in a sheet form. It would also be possible to use a single layered tubing for the second covering material 12. The thickness of the first and/or second covering material 14, 12 falls within the range of from 0.02-0.15 mm.

[0040] Afterwards, in step S106, the arrangement is packed and then sintered so that the first and second covering materials 12, 14 and the base stent 10 are integrated so as to adhere to one another. Afterwards, the stent graft is unpacked.

[0041] After that step S106, in the next step S108, the second covering material 12 is locally ablated so that a discrete portion of the base stent is uncovered by the second covering material. It is also envisaged that the second covering material 12 is only made thinner, without being entirely ablated. The ablation of the second covering material can be accomplished by using a laser, such as a carbon dioxide polymer evaporating laser 22. The carbon dioxide polymer evaporating laser 22 is applied to the outside layer of the stent graft 100 in a controlled manner so as to locally remove by vaporizing the second covering material 12. In the configuration that is shown in FIG. 1, the laser 22 is applied in a grazing manner so that it would, in the context of that drawing, be propagating along a direction that is perpendicular to the sheet on which the drawing is printed. Of course, this is just exemplary, and other angles of propagation are possible as discussed above. Afterwards, the stent graft 100 is removed from the mandrel 16 and is trimmed if necessary.

[0042] By this ablation, gaps 20 in the second covering material 12 are provided that have the form of a spiral 21. The spiral 21 ends in two ring-shaped gaps 18 at either longitudinal end of the stent graft 100.