Stent-graft having flexible geometries and methods of producing the same

• US 20070208421A1
• Filed: 03/01/2006
• Published: 09/06/2007
• Est. Priority Date: 03/01/2006
• Status: Active Grant

• Current Assignee: Lifeshield Sciences LLC (Acacia Research Corporation)
• Original Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Inventors: Quigley, Fergus
• Granted Patent: US 8,025,693 B2
• Time in Patent Office: Days
• US Class Current: 623/1.440
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/89 the wire-like elements comprising two or more adjacent rings flexibly connected by separate members
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2250/0028 differing in fibre orientations
• CPC Class Codes: A61F 2250/0029 differing in bending or flexure capacity

Abstract

A stent-graft or prosthesis (10) with enhanced flexibility, in particular enhanced bending flexibility, includes a radially distensible stent (24) and at least one continuously uninterrupted ePTFE tubular graft or covering (18) having a node and fibril structure. The tubular stent (24) includes opposed open ends (12′, 14′) and a stent wall structure (26) having opposed exterior (28) and luminal surfaces (30). The ePTFE covering (18) is securably disposed to at least one of the stent surfaces (28, 30). The ePTFE graft or covering (18) includes a tubular wall (16) that is continuously uninterrupted and desirably substantially free of slits, apertures and folds. The ePTFE graft (18) further includes a first region (20) and a second region (22), where the first region (20) has a different bending flexibility from the second region (22).

Claims

1. An endoprosthesis comprising:

a radially distensible, tubular stent comprising opposed open ends and a stent wall structure having opposed exterior and luminal surfaces; and

a continuous and seamless ePTFE tubular covering having a node and fibril structure securably disposed to at least one of said stent surfaces, said covering comprising an uninterrupted tubular wall comprising a first region and a second region, said first region having a different bending flexibility from said second region.

2. The endoprosthesis of claim 1, wherein said stent further comprises a longitudinal length, wherein said longitudinal length remains substantially constant upon radial expansion or radial contraction of said stent.

3. The endoprosthesis of claim 1, wherein said stent is a self-expanding stent, a balloon-expandable stent or combinations thereof.

4. The endoprosthesis of claim 1, wherein said stent comprises a biocompatible material selected from the group consisting of metallic materials, polymeric materials, bioabsorbable materials, biodegradable materials, and combinations thereof.

5. The endoprosthesis of claim 1, wherein said stent comprises a plurality of undulating stent segments.

6. The endoprosthesis of claim 1, wherein said stent comprises an undulating wire helically wound into a plurality of circumferential adjacent windings to define said stent wall structure.

7. The endoprosthesis of claim 6, wherein said first region of said ePTFE covering is securably attached to at least one of said circumferential windings of said undulating wire and said second region of said ePTFE covering is disposed between at least two adjacent windings of said circumferential windings of said undulating wire, wherein said second region has a greater bending flexibility that said first region.

8. The endoprosthesis of claim 7, wherein said second region of said covering comprises at least one circumferential recess.

9. The endoprosthesis of claim 8, wherein said first region of said covering is free of circumferential recesses.

10. The endoprosthesis of claim 9, wherein said second region preferentially deforms when subjected to a bending stress as compared to said first region.

11. The endoprosthesis of claim 7, wherein the node and fibril structure of said first region is different from the node and fibril structure of said second region.

12. The endoprosthesis of claim 8, wherein the fibril structure at said first region is more circumferentially orientated than the fibril structure at said second region.

13. The endoprosthesis of claim 12, wherein the fibril structure at said first region was formed by axially stretching said first region by a first amount and the fibril structure at said second region was formed by axially stretching said second region by a second amount, said first amount being greater than said second amount.

14. The endoprosthesis of claim 13, wherein said first amount of axial stretching is from about 1,000% to about 2,000% and said second amount of axial stretching is from about 200% to about 800%.

15. The endoprosthesis of claim 14, wherein said second region preferentially deforms when subjected to a bending stress as compared to said first region.

16. The endoprosthesis of claim 1, further comprising a second ePTFE tubular graft securably disposed to the other of one said stent surfaces.

17. An implantable prosthesis comprising:

a non-textile polymeric tubular graft comprising a continuously uninterrupted tubular wall comprising a first region and a second region, wherein said first region has a different bending flexibility than said second region.

18. The prosthesis of claim 17, wherein said first region has a different plastic deformation rate than said second region.

19. The prosthesis of claim 17, wherein said graft comprises polymeric graft material selected from the group consisting of polyesters, polypropylenes, polyethylenes, polyurethanes, polynaphthalenes, polytetrafluoroethylenes, expanded polytetrafluoroethylenes, silicones, and combinations and copolymers thereof.

20. The prosthesis of claim 17, wherein said graft comprises expanded polytetrafluoroethylene.

21. The prosthesis of claim 20, wherein said ePTFE graft comprises a node and fibril structure, and further wherein the node and fibril structure of said first region is different from the node and fibril structure of said second region.

22. The prosthesis of claim 21, wherein the fibril structure at said first region is more circumferentially orientated than the fibril structure at said second region.

23. The prosthesis of claim 22, wherein the fibril structure at said first region was formed by axially stretching said first region by a first amount and the fibril structure at said second region was formed by axially stretching said second region by a second amount, said first amount being greater than said second amount.

24. The prosthesis of claim 23, wherein said first amount of axial stretching is from about 1,000% to about 2,000% and said second amount of axial stretching is from about 200% to about 800%.

25. The prosthesis of claim 23, wherein said second region preferentially deforms when subjected to a bending stress as compared to said first region.

26. The prosthesis of claim 23, further comprising a radially distensible, tubular stent, said stent comprising an undulating wire helically wound into a plurality of circumferential windings to define a stent wall structure, wherein said first region of said ePTFE graft is securably attached to at least one of said circumferential windings of said undulating wire and said second region of said ePTFE graft is disposed between at least two adjacent windings of said circumferential windings of said undulating wire.

27. The prosthesis of claim 17, wherein said tubular wall is substantially free of folds, crimps and pleats.

28. The prosthesis of claim 17, further comprising a radially distensible, tubular stent.

29. The prosthesis of claim 28, wherein said stent comprises a plurality of undulating stent segments.

30. The prosthesis of claim 28, wherein said stent comprises an undulating wire helically wound into a plurality of circumferential windings to define a stent wall structure.

31. The prosthesis of claim 30, wherein said first region of said graft is securably attached to at least one of said circumferential windings of said undulating wire and said second region of said graft is disposed between at least two adjacent windings of said circumferential windings of said undulating wire.

32. The prosthesis of claim 17, wherein said second region comprises at least one circumferential recess.

33. The prosthesis of claim 32, wherein said first region is free of circumferential recesses.

34. The prosthesis of claim 33, further comprising a radially distensible, tubular stent, said stent comprising an undulating wire helically wound into a plurality of circumferential windings to define a stent wall structure, wherein said first region of said graft is securably attached to at least one of said circumferential windings of said undulating wire and said second region of said graft is disposed between at least two adjacent windings of said circumferential windings of said undulating wire.

35. The prosthesis of claim 34, wherein said graft comprises expanded polytetrafluoroethylene.

36. A method of making a stent-graft comprising:

providing a radially distensible, tubular stent comprising opposed open ends and a stent wall structure having opposed exterior and luminal surfaces;

providing a continuously uninterrupted ePTFE tubular graft having a node and fibril structure, said graft securably disposed to one of said stent surfaces, said graft comprising a continuously uninterrupted tubular wall comprising a first region and a second region; and

providing said first region with a different bending flexibility from said second region.

37. The method of claim 36, wherein the step of providing said first region with a different bending flexibility from said second region comprises:

providing at least one circumferential recess at said second region of said graft.

38. The method of claim 37, wherein said first region of said graft is free of circumferential recesses.

39. The method of claim 36, wherein the step of providing said first region with a different bending flexibility from said second region comprises:

axially stretching said first region by a first amount; and

axially stretching said second region by a second amount,

wherein said first amount being greater than said second amount.

40. The method of claim 39, wherein said first amount of axial stretching is from about 1,000% to about 2,000% and said second amount of axial stretching is from about 200% to about 800%.

41. A method of supporting a stent-graft deployed within a bodily lumen, comprising:

providing a endoprosthesis comprising a radially distensible, tubular stent comprising opposed open ends and a stent wall structure having opposed exterior and luminal surfaces; and

a continuous and seamless ePTFE tubular covering having a node and fibril structure securably disposed to at least one of said stent surfaces, said covering comprising an uninterrupted tubular wall comprising a first region and a second region, said first region having a different bending flexibility from said second region;

deploying the endoprosthesis within the stent-graft; and

expanding the endoprosthesis to support the stent-graft.