Stents incorporating a plurality of strain-distribution locations

• US 8,574,287 B2
• Filed: 06/14/2012
• Issued: 11/05/2013
• Est. Priority Date: 06/14/2011
• Status: Active Grant

• Current Assignee: Endospan Ltd.
• Original Assignee: Endospan Ltd.
• Inventors: Benary, Raphael, Shalev, Alon
• Primary Examiner(s): Sweet, Thomas J
• Assistant Examiner(s): SCHALL, MATTHEW WAYNE
• Application Number:
  US13/523,296
• Publication Number:
  US 20120323305A1
• Time in Patent Office: 509 Days
• Field of Search: 623/1.13, 623/1.15
• US Class Current: 623/1.15
• 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 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching

Abstract

A stent (120) has proximal and distal ends (140, 142), and is configured to assume radially-compressed and radially-expanded states. The stent (120) comprises a plurality of circumferential bands (122) disposed about a longitudinal axis (123) of the stent (120), each of which bands (122) comprises a plurality of struts (124) connected to one another. At least one of the bands (122) is shaped so as to define a plurality of distally-directed peaks (126) alternating with a plurality of proximally-directed troughs (128), and one or more strain-concentration modules (132). Each of the modules (132) has a central axis (156) parallel to the longitudinal axis (123) of the stent (120), and comprises: (a) an open loop section (150), which comprises one of the distally-directed peaks (126); (b) a primary neck section (152); and (c) a secondary section (154). Other embodiments are also described.

Claims

1. Apparatus comprising a stent (120) having proximal and distal ends (140, 142), which is configured to assume radially-compressed and radially-expanded states, and which comprises a plurality of circumferential bands (122) disposed about a longitudinal axis (123) of the stent (120), each of which bands (122) comprises a plurality of struts (124) connected to one another,

wherein at least one of the bands (122) is shaped so as to define a plurality of distally-directed peaks (126) alternating with a plurality of proximally-directed troughs (128), and one or more strain-concentration modules (132), each of which modules (132) has a central axis (156) parallel to the longitudinal axis (123) of the stent (120), and comprises:

an open loop section (150), which (a) comprises one of the distally-directed peaks (126), and (b) is shaped so as to define first and second proximal open loop ends (160A, 160B) disposed on opposite sides of the central axis (156), wherein, when the stent (120) is in its radially-compressed state, the open loop section (150) has a greatest outer width (W) measured perpendicular to the central axis (156), and a first distance (D1) between the first and the second proximal open loop ends (160A, 160B) is less than 20% of the greatest outer width (W);

a primary neck section (152), which comprises first and second primary segments (162A, 162B) of first and second ones of the struts (164A, 164B), respectively, disposed on opposite sides of the central axis (156), wherein first and second distal ends (166A, 166B) of the first and the second primary segments (162A, 162B) are connected to the first and the second proximal open loop ends (160A, 160B) at first and second primary junctions (168A, 168B), respectively, and wherein each of the first and the second primary segments (162A, 162B) has a length (L1) equal to at least 33% of the greatest outer width (W) of the open loop section (150); and

a secondary section (154), which comprises first and second secondary segments (170A, 170B) of the first and the second struts (164A, 164B), respectively, disposed on opposite sides of the central axis (156), wherein first and second distal ends (172A, 172B) of the first and the second secondary segments (170A, 170B), respectively, are connected to first and second proximal ends (174A, 174B) of the first and the second primary segments (170A, 170B) at first and second secondary junctions (176A, 176B), respectively,

wherein the first primary segment (162A) defines a first primary straight line (180A), which passes through the first distal end (166A) and the first proximal end (174A) of the first primary segment (162A), and the second primary segment (162B) defines a second primary straight line (180B), which passes through the second distal end (166B) and the second proximal end (174B) of the second primary segment (162B),

wherein the first primary line (180A) defines a distal-facing primary angle (α

) with the second primary line (180B) which (i) has a compressed value of between 0 and 5 degrees, when the stent (120) is in its radially-compressed state, and (ii) has an expanded value that is between (x) 5 degrees greater than the compressed value of the primary angle (α

) and (y) 60 degrees, when the stent (120) is in its radially-expanded state,

wherein the first secondary segment (170A) defines a first secondary straight line (182A), which passes through (i) the first distal end (172A) of the first secondary segment (170A) and (ii) a first point (184A) on the first secondary segment (170A) at a second distance (D2) from the first distal end (172A) of the first secondary segment (170A), and the second secondary segment (170B) defines a second secondary straight line (182B), which passes through (i) the second distal end (172B) of the second secondary segment (170B) and (ii) a second point (184B) on the second secondary segment (170B) at the second distance (D2) from the second distal end (172B) of the second secondary segment (170B), which second distance (D2) equals 25% of the greatest outer width (W), and

wherein the first secondary line (182A) defines a distal-facing secondary angle (β

) with the second secondary line (182B) which (i) has a compressed value of between 0 and 5 degrees, when the stent (120) is in its radially-compressed state, and (ii) has an expanded value that is greater than the expanded value of the primary angle (α

), when the stent (120) is in its radially-expanded state.

2. The apparatus according to claim 1, wherein the expanded value of the secondary angle (β

) is between (x) 5 degrees greater than the expanded value of the primary angle (α

) and (y) 90 degrees.

3. The apparatus according to claim 1, wherein radii of curvature of the first and the second struts (164A, 164B) at the first and the second secondary junctions (176A, 176B), respectively, are less than 50% of a length of the first primary segment (162A) and 50% of a length of the second primary segment (162B), respectively, when the stent (120) is in its radially-expanded state.

4. The apparatus according to claim 1, wherein the stent (120) is configured to assume a plurality of partially radially-compressed states between its radially-compressed and its radially-expanded states, and wherein, when the stent (120) is in at least one of its partially radially-compressed states, the primary angle (α

) has a partially-compressed value of between 0 and 10 degrees, and the secondary angle (β

) has a partially-compressed value that is greater than the partially-compressed value of the primary angle (α

).

5. The apparatus according to claim 1, wherein none of the struts (124), other than the first and the second struts (164A, 164B), is connected to the first primary junction (168A) or the second primary junction (168B).

6. The apparatus according to claim 1, wherein none of the struts (124), other than the first and the second struts (164A, 164B), is connected to the first secondary junction (176A) or the second secondary junction (176B).

7. The apparatus according to claim 1, wherein the first and the second primary segments (162A, 162B) of the primary neck section (152) are straight when the stent (120) is in its radially-compressed state.

8. The apparatus according to claim 1, wherein the first and the second primary segments (162A, 162B) of the primary neck section (152) are straight when the stent (120) is in its radially-expanded state.

9. The apparatus according to claim 1, wherein the first and the second primary segments (162A, 162B) of the primary neck section (152) are curved when the stent (120) is in its radially-expanded state, and are straight when the stent (120) is in its radially-compressed state.

10. The apparatus according to claim 1, wherein the stent (120) is shaped so as to generally define a cylinder when in its radially-expanded state, and wherein the struts (124) of the strain-concentration modules (132) coincide with a surface of the cylinder.

11. The apparatus according to claim 1, wherein the at least one of the bands (122) is serpentine at least when the stent (120) is in its radially-expanded state.

12. The apparatus according to claim 1, wherein the at least one of the bands (122) extends around an entire circumference of the stent (120).

13. The apparatus according to claim 1, wherein a length of the open loop section, measured along a perimeter thereof, is at least 0.7 mm.

14. The apparatus according to claim 1, wherein first and second proximal ends (174A, 174B) of the first and second secondary segments (170A, 170B), respectively, are directly or indirectly connected to another one of the bands (122).

15. The apparatus according to claim 1,

wherein the secondary section (154) is a secondary neck section (154),

wherein each of the first and second secondary segments (170A, 170B) has a length equal to at least 66% of the greatest outer width (W) of the open loop section (150),

wherein each of the one or more strain concentration modules (132) further comprises a tertiary section (200), which comprises first and second tertiary segments (202A, 202B) of the first and the second struts (164A, 164B), respectively, disposed on opposite sides of the central axis (156), wherein first and second distal ends (204A, 204B) of the first and the second tertiary segments (202A, 202B), respectively, are connected to first and second proximal ends (206A, 206B) of the first and the second secondary segments (170A, 170B) at first and second tertiary junctions (208A, 208B), respectively,

wherein the first tertiary segment (202A) defines a first tertiary straight line (210A), which passes through (i) the first distal end (204A) of the first tertiary segment (202A) and (ii) a third point (212A) on the first tertiary segment (202A) at the second distance (D2) from the first distal end (204A) of the first tertiary segment (202A), and the second tertiary segment (202B) defines a second tertiary straight line (210B), which passes through (i) the second distal end (204B) of the second tertiary segment (202B) and (ii) a fourth point (212B) on the second tertiary segment (202B) at the second distance (D2) from the second distal end (204B) of the second tertiary segment (202B), and

wherein the first tertiary line (210A) defines a tertiary angle (θ

) with the second tertiary line (210B) which (i) has a compressed value of at least 105% of the compressed value of angle β

(beta), when the stent is in its radially-compressed state, and (ii) has an expanded value that is between (x) 120% of the expanded value of the secondary angle (β

) and (y) 135 degrees, when the stent (120) is in its radially-expanded state.

16. The apparatus according to claim 15, wherein the first and the second secondary segments (170A, 170B) of the secondary neck section (154) are straight when the stent (120) is in its radially-compressed state.

17. The apparatus according to claim 15, wherein the first and the second secondary segments (170A, 170B) of the secondary neck section (154) are straight when the stent (120) is in its radially-expanded state.

18. The apparatus according to claim 1, wherein the stent (120) comprises a metal.

19. The apparatus according to claim 18, wherein the metal comprises a superelastic alloy.

20. The apparatus according to claim 19, wherein the superelastic alloy comprises Nitinol.

21. The apparatus according to claim 1, wherein the stent (120) is self-expanding from the radially-compressed state to the radially-expanded state.

22. The apparatus according to claim 1, wherein the radially-expanded relaxed state of the stent (120) is achieved by heat-setting of the stent (120) in the radially-expanded state that is more radially expanded than an initial as-cut state of the stent (120).

23. The apparatus according to claim 1, wherein the circumferential bands (122) comprise a plurality of substantially M-shaped segments.

24. The apparatus according to claim 1, wherein the circumferential bands (122) are adjacently connected therebetween.

25. The apparatus according to claim 1, further comprising a graft member (30), which covers at least a portion of the stent (120) and is securely connected thereto.