Radially expandable stent

• US 6,231,598 B1
• Filed: 09/24/1998
• Issued: 05/15/2001
• Est. Priority Date: 09/24/1997
• Status: Expired due to Term

• Current Assignee: Cook Medical Incorporated (Cook Group Incorporated)
• Original Assignee: Cook Incorporated (Cook Group Incorporated), MED Institute, Inc. (Cook Group Incorporated)
• Inventors: Boatman, Scott E., Bates, Brian L., Hoffa, Michael C., Fearnot, Neal E., Voorhees, William D. III, Herald, Coy M., Berry, Dale T.
• Primary Examiner(s): Willse, David H.
• Assistant Examiner(s): GHERBI, SUZETTE JAIME J
• Application Number:
  US09/160,122
• Time in Patent Office: 964 Days
• Field of Search: 623/1.15, 623/1.16, 623/1.2
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/88 the wire-like elements formed as helical or spiral coils forming a net-like or mesh-like structure A61F2/90
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91508 the meander having a difference in amplitude along the band
• CPC Class Codes: A61F 2002/91516 the meander having a change in frequency along the band
• CPC Class Codes: A61F 2002/91525 within the whole structure different bands showing different meander characteristics, e.g. frequency or amplitude
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2002/91566 connected trough to trough
• CPC Class Codes: A61F 2002/91575 connected peak to trough
• CPC Class Codes: A61F 2002/91583 by a bridge, whereby at least one of its ends is connected along the length of a strut between two consecutive apices within a band
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2250/0036 differing in thickness
• CPC Class Codes: A61F 2250/0098 radio-opaque, e.g. radio-opaque markers
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61L 31/18 Materials at least partially X-ray or laser opaque

Abstract

A radially expandable stent (10) made from a cannula or sheet of biocompatible material that includes at least one longitudinal segment (14) comprised of a series of laterally interconnected closed cells (13). Each closed cell of a longitudinal segment is defined laterally by a pair of longitudinal struts (15, 16) that are interconnected at each end by a circumferentially adjustable member (19, 20). When the stent is expanded using a balloon (47), the opposing circumferentially adjustable members deform to allow circumferential expansion of the longitudinal segment, while the length of the segment, as defined by the longitudinal struts, is maintained. Self-expanding versions of the stent utilize a nickel-titanium alloy. Adjacent longitudinal segments are joined by flexible interconnection segments (21) that permit the stent to bend laterally. The flexible interconnection segment is comprised of curvilinear struts (22, 23) that form a series of serpentine bends (81) that distribute lateral bending forces. In a preferred embodiment, a short strut interconnects longitudinal segments and an adjacent interconnection segment. Each interconnection strut attaches to the longitudinal segment within a region (27) at the end (17) of a longitudinal strut (15) dividing two adjacent closed cells.

Claims

1. A radially expandable stent (10) comprising:

an elongated member (11) having a passage (12) extending longitudinally therein and a first longitudinal segment (14) including a plurality of cells (13), selected of said cells (13) each including a first and a second longitudinal strut (15, 16), said first longitudinal segment (14) having a first expanded radial stiffness greater than 4.87×

10<sup>−

3</sup> lbs (force) per millimeter (length); and

said elongated member (11) also having an interconnection segment (21) connected to said first longitudinal segment (14) and having a second expanded radial stiffness less than said first expanded radial stiffness.

2. The stent of claim 1, wherein said first longitudinal segment (14) and said interconnection segment (21) have a combined lateral bending stiffness less than 5.3×

10<sup>−

5</sup> in-lb (force) per degree per millimeter (length).

3. The stent of claim 1, wherein said interconnection segment (21) includes a plurality of interconnected curvilinear struts (22, 23) forming an approximately serpentine pattern.

4. The stent of claim 1, further comprising a connecting strut (36) interconnecting said first longitudinal segment (14) and said interconnection segment (21).

5. The stent of claim 1 further comprising a plurality of said longitudinal segments (11) adjacent ones being interconnected by a said interconnection segment (21).

6. The stent of claim 1, wherein said interconnection segment (21) includes a plurality of interconnected linear struts (22, 23) forming a zig-zag pattern.

7. The stent of claim 1, wherein said stent is self-expanding and wherein said elongated member comprises a nickel-titanium alloy material.

8. The stent of claim 1, wherein selected of said cells are closed cells (13) having opposed longitudinal struts (15 or 16) and opposed circumferentially adjustable members (19,20).

9. The stent of claim 1, wherein at least one end of said stent includes a radiopaque marker (48).

18. The stent of claim 1, wherein said interconnection segment (21) includes a plurality of struts each interconnected to adjacent other ones of said plurality of said struts of said interconnection segment to define a pattern of struts extending circumferentially around said passage (12).

19. The stent of claim 1, wherein the elongated member is defined from a single cannula.

23. The stent of claim 8, wherein said circumferentially adjustable members (19,20) protrude into said closed cells (13) when said stent is unexpanded.

24. The stent of claim 8, wherein a said circumferentially adjustable member (19 or 20) protrudes into a said closed cell and a said circumferentially adjustable member (20 or 19) protrudes outwardly from said closed cell.

25. The stent of claim 8, wherein said circumferentially adjustable members (19,20) protrude outwardly from said closed cells (13) when said stent is unexpanded.

26. The stent of claim 8, wherein said interconnection segment (21) includes zig-zag struts (81) that are interconnected to each other, and interconnections thus formed are disposed between protrusions of said circumferentially adjustable members (19,20) of adjacent cells of adjacent longitudinal segments (14,25) when said stent is unexpanded.

27. The stent of claim 26, wherein closed cells (13) of adjacent ones of said longitudinal segments are radially offset from each other by half a cell width.

28. The stent of claim 25, wherein closed cells (13) of adjacent ones of said longitudinal segments are axially aligned with each other.

29. The stent of claim 1, wherein said interconnection segment (21) is connected to said longitudinal segment (14) by at least one serpentine-shaped interconnection strut (80).

30. The stent of claim 9, wherein said radiopaque marker (167) is “

T”

-shaped.

31. The stent of claim 1, wherein said stent (10) spaced inwardly from ends thereof includes an opening (160), and said stent further includes a plurality of radiopaque markers (161, 161′

,161″

,161′

″

) affixed to said stent about said opening to assist alignment of the opening with a side branch (166) of a main vessel (168).

10. A radially expandable stent (10) comprising:

an elongated member (11) having a passage (12) extending longitudinally therein and a first longitudinal segment (14), said first longitudinal segment (14) including a plurality of cells (13) and having a first expanded radial stiffness; and

said elongated member (11) also having an interconnection segment (21) connected to said first longitudinal segment (14) and having a second expanded radial stiffness less than said first expanded radial stiffness, wherein said first longitudinal segment (14) and said interconnection segment (21) have a combined lateral bending stiffness less than 3.33×

10<sup>−

6</sup> in-lb (force) per degree per millimeter (length).

11. The stent of claim 10, wherein selected of said cells each includes a first and a second longitudinal strut (15, 16).

12. The stent of claim 10, wherein first expanded radial stiffness is greater than 4.87×

10<sup>−

3</sup> lbs (force) per millimeter (length).

20. The stent of claim 10, wherein said interconnection segment (21) includes a plurality of struts each interconnected to adjacent other ones of said plurality of said struts of said interconnection segment to define a pattern of struts extending circumferentially around said passage (12).

21. The stent of claim 10, wherein the elongated member is defined from a single cannula.

13. A radially expandable stent (10) comprising:

an elongated member (11) having a passage (12) extending longitudinally therein, said elongated member (11) having a first longitudinal segment (14) including a plurality of laterally interconnected cells (13), selected of said cells (13) each including a first and a second longitudinal strut (15,16), said longitudinal struts of said selected cells (13) being interconnected by at least one pair of circumferentially adjustable members (19, 20), said circumferentially adjustable members (19, 20) permitting the circumferential expansion of the longitudinal segment (14) with minimal change in axial length of said longitudinal struts (15,16) when said longitudinal segment (14) is radially expanded;

said longitudinal struts remaining substantially parallel with the longitudinal axis of said stent, and

said stent further comprising a second longitudinal segment (25) like said first longitudinal segment and an interconnection segment (21) comprised of a plurality of interconnected curvilinear or linear struts (22,23) forming an approximately serpentine or zig-zag pattern, said interconnection segment being radially expandable, and said interconnection segment joined to at least one said first longitudinal strut (15) of the first longitudinal segment (14) and to at least one longitudinal strut (32) of said second longitudinal segment (25).

14. The stent of claim 13, wherein adjacent cells of said selected cells (13) share a common said first longitudinal strut (15) and common said second longitudinal strut (16) with respective laterally adjacent second cells (29, 29′

).

15. The stent of claim 13, wherein said stent further includes at least one radiopaque marker (48) at an end thereof.

16. The stent of claim 13, wherein said stent is self-expanding and comprises a nickel-titanium alloy material.

17. The stent of claim 13, wherein said stent has a recoil of less than 3.3%.

22. A radially expandable stent (10) comprising:

an elongated member (11) having a passage (12) extending longitudinally therein, said elongated member (11) having a first longitudinal segment (14) including a plurality of laterally interconnected cells (13), selected of said cells (13) each including a first and a second longitudinal strut (15,16), said longitudinal struts of said selected cells (13) being interconnected by at least one pair of circumferentially adjustable members (19, 20), said circumferentially adjustable members (19, 20) permitting the circumferential expansion of the longitudinal segment (14) with minimal change in axial length of said longitudinal struts (15,16) when said longitudinal segment (14) is radially expanded;

said longitudinal struts remaining substantially parallel with the longitudinal axis of said stent, and

said first longitudinal segment (14) having a first expanded radial stiffness, and said elongated member (11) also having an interconnection segment (21) connected to said first longitudinal segment (14) and having a second expanded radial stiffness less than said first expanded radial stiffness.