Longitudinally flexible stent

• US 20060178724A1
• Filed: 03/31/2006
• Published: 08/10/2006
• Est. Priority Date: 03/01/2000
• Status: Active Grant

• Current Assignee: Medinol Limited (Medinol USA Incorporated)
• Original Assignee: Medinol Limited (Medinol USA Incorporated)
• Inventors: Richter, Jacob, Pinchasik, Gregory
• Granted Patent: US 8,317,851 B2
• Time in Patent Office: Days
• US Class Current: 623/1.150
• 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 2230/0054 V-shaped

Abstract

An intravascular stent especially suited for implanting in curved arterial portions. The stent retains longitudinal flexibility after expansion. The stent is formed of intertwined meander patterns forming triangular cells. The triangular cells are adapted to provide radial support, and also to provide longitudinal flexibility after expansion. The triangular cells provide increased coverage of a vessel wall. The stent can have different portions adapted to optimize radial support or to optimize longitudinal flexibility. The stent can be adapted to prevent flaring of portions of the stent during insertion.

Claims

1. A stent consisting of essentially triangular cells, each triangular cell comprising:

a first loop containing section, the first loop containing section arranged generally in the circumferential direction,

a second loop containing section, the second loop containing section arranged generally in the circumferential direction and joined to the first loop containing section at a first junction; and

a third loop containing section joined to the first loop containing section at a second junction and joined to the second loop containing section at a third junction;

wherein a plurality of first loop containing sections form a first band of loops and a plurality of second and third loop containing sections form a second band of loops, the first and second bands alternating along the longitudinal axis of the stent; and

wherein the first, second, and third loop containing sections include legs that are oriented along the longitudinal axis, and at least one of the legs in any one of the loop containing sections is shorter than at least one other leg in the same loop containing section within the triangular cell; and

wherein the first loop containing section has wider legs than the second and third loop containing sections.

2. A stent according to claim 1, wherein the first loop containing section is relatively adapted to enable radial support, and the second and third loop containing sections are relatively adapted to enable longitudinal flexibility.

3. A stent according to claim 1, wherein the second and third loop containing sections are adapted to compensate for foreshortening of the first loop containing section when the stent is expanded.

4. A stent according to claim 3, wherein the first loop containing section has three loops.

5. A stent according to claim 4, wherein the second loop containing section has two loops.

6. A stent according to claim 5, wherein the third loop containing section has two loops.

7. A stent according to claims 1, wherein the second and first junctions are circumferentially aligned.

8. A stent according to claims 1, wherein each cell in the stent encompasses the same area.

9. A stent according to claims 1, wherein the cell is arranged so that when expanded a length of the cell along a circumference of the stent is longer than a length of a cell along the longitudinal axis of the stent.

10. A stent according to claims 1, wherein the stent is made from NiTi.

11. A stent according to claim 12, wherein a cell of the stent is symmetrical about a line parallel to a longitudinal axis of the stent.

12. A stent according to claims 1, wherein at least one cell with a larger size is provided to allow access to a side branch lumen.

13. A stent according to claims 1, wherein the cells are arranged into a plurality of bands, and the cells in one band are larger than the cells in the remaining band so as to provide access to a side branch in a vessel.

14. A stent according to claims 1, wherein the cells are arranged into a plurality of bands and the cells in at least one band are adapted to have a different radial force than the cells in the remaining bands.

15. A stent according to claims 1, wherein the cells are arranged into a plurality of bands and the cells in at least one band are adapted to have a different longitudinal flexibility than the cells in the remaining bands.

16. A stent according to claims 1, wherein the cells are arranged into a plurality of bands and the cells in at least one band are adapted so that upon expansion of the stent the band expands to a diameter which is different than the diameter of the remaining portions of the stent.

17. A stent according to claims 1, wherein the cells are arranged into a plurality of bands, and the number of cells in at least one band is different than the number of cells in another band.

18. A stent according to claims 1, wherein the stent is finished in one of the following ways:

plating with a radiopaque material, plating with a protective material, embedding with medicine, or covering with a material.

61. A stent according to claim 1, wherein the stent is made of super elastic Nitinol.

62. A stent according to claim 1, wherein the stent is made of a radiopaque material, comprising an alloy of Chromium and Cobalt.

19. A stent for widening a vessel in the human body consisting of:

a plurality of first meander patterns having loops;

a plurality of second meander patterns having loops intertwined with the first meander patterns to form triangular cells, each of said triangular cells having at least one loop containing section arranged generally in the circumferential direction, the loop containing section having legs that are oriented along the longitudinal axis of the stent, wherein at least one of the legs of the loop containing section is shorter than at least one other leg in the same loop containing section within the triangular cell and the first meander patterns are joined together through the second meander patterns; and

wherein the legs of the first meander pattern are wider than at least one of the legs of the second meander pattern.

20. A stent according to claim 19 wherein the first meander patterns are comprised of:

even first meander patterns; and

odd first meander patterns which are 180°

out of phase with the even first meander patterns, the odd first meander patterns occurring between every two even first meander patterns.

21. A stent according to claims 19 wherein the second meander patterns are comprised of:

even second meander patterns; and

odd second meander patterns occurring between every two even second meander patterns.

22. A stent according to claim 19, wherein each of the triangular cells is comprised of a first loop containing section, a second loop containing section, and a third loop containing section.

23. A stent according to claim 22, wherein the first loop containing section is formed by a portion of a first meander pattern and the second and third loop containing sections are formed by portions of one or more second meander patterns.

24. A stent according to claim 22, wherein the first meander pattern has three loops per cell.

25. A stent according to claim 22, wherein the second meander patterns comprise at least four loops per cell.

26. A stent according to claim 22 wherein the first and second meander patterns have center lines that are substantially orthogonal.

27. A stent according to claim 22, wherein the first loop containing section has two loops facing toward the interior of the cell.

28. A stent according to claim 22, wherein the second and third loop containing sections each have two loops.

29. A stent according to claims 22, wherein the loops of the second and third loop containing sections are adapted to compensate for the tendency of the loops of the first loop containing section to foreshorten when the stent is expanded.

30. A stent according to claims 22, wherein the odd and even second meander portions have portions in common wherein said meanders run in the same direction.

57. A stent according to claims 21, wherein the second meander patterns consist essentially of even second meander patterns.

63. A stent according to claim 19, wherein said stent is made of super elastic Nitinol.

64. A stent according to claim 19, wherein, said stent is made of a radiopaque material, comprising an alloy of Chromium and Cobalt.

31. A multicellular stent comprising;

a plurality of bands of first cells, each first cell including a first loop disposed generally longitudinally opposite a second loop and a first pair of flexible compensating members joined to the cell sections containing the first and second loop;

a plurality of bands of second cells, each second cell including a third loop disposed generally longitudinally opposite a fourth loop and a second pair of flexible members joined to the cell sections containing the third and fourth loops to form a cell, the bands of second cells interspersed with the bands of first cells,

wherein the first loop and the second loop are substantially aligned along a longitudinal axis of the stent, and wherein the third loop and the fourth loop are offset along the longitudinal axis.

32. A multicellular stent according to claim 31 wherein the loops of the cell are wider that the flexible members of the cell so that the loops provide more radial support.

33. A multicellular stent according to claim 31 wherein each flexible member of the second pair of flexible members includes:

a first portion with a first end and a second end;

a second portion with a first end and a second end;

a third portion with a first end and a second end;

a curved portion with a first area of inflection disposed between the second end of the first portion and the second end of the second portion; and

a curved portion with a second area of inflection disposed between the first end of the second portion and the first end of the third portion.

34. A multicellular stent according to claim 33 wherein each flexible member of the first pair of flexible members includes a flexible arcuate compensating member.

35. A multicellular stent according to claim 31, wherein the bands of cells alternate with the bands of the second cells.

36. A multicellular stent according to claim 31, wherein the bands of the cells are chosen so as to produce sections of the stent with increased radial rigidity.

37. A multicellular stent according to claim 31, wherein the bands of cells at the ends of the stents are adapted to be more longitudinally flexible than the bands of cells in the remainder of the stent.

38. A multicellular stent according to claim 31, wherein the stent is made from either stainless steel or NiTi.

58. A multicellular stent according to claims 31, wherein the stent is made of super elastic Nitinol.

59. A multicellular stent according to claims 31, wherein the stent is made of a radiopaque material, comprising an alloy of Chromium and Cobalt.

60. A stent according to claim 31, wherein the stent is exposed to repeated flexing of a vessel caused by the systolic cycle in a coronary artery.

39. A multicellular stent comprising:

a plurality of bands of square cells, each square cell including a first loop disposed generally longitudinally opposite a second loop, and a first pair of flexible compensating members joined to the legs of the first and second loop;

a plurality of bands of triangular cells, each triangular cell comprising a first loop containing section arranged generally in the circumferential direction, a second loop containing section connected to the first loop containing section, and a third loop containing section connected to the first loop containing section and the second loop containing section,

wherein the bands of triangular cells are interspersed with the bands of square cells to form the stent.

40. A multicellular stent according to claim 39, wherein the bands of the square cells alternate with the bands of the triangular cells.

41. A multicellular stent according to claim 39, wherein the bands of cells at the ends of the stents are adapted to be more longitudinally flexible than the bands of cells in the remainder of the stent.

42. A multicellular stent according to claim 39, wherein the first loop containing section has two loops facing the interior of the cell.

43. A multicellular stent according to claim 39, wherein the second and third loop containing sections each have at least one loop facing the interior of the cell.

44. A multicellular stent according to claim 39, wherein the first and second loop are formed of members which are wider than the pair of flexible compensating members.

45. A multicellular stent according to claim 39, wherein the first loop is formed of members which are wider than members forming the second and third loop.

46. A multicellular stent according to claim 39, wherein the first loop containing section has some legs of loops which are shorter than other legs of loops.

47. A stent according to claims 39, wherein the stent is made from NiTi.

48. A stent according to claim 47, wherein a cell of the stent is symmetrical about a line parallel to a longitudinal axis of the stent.

49. A stent for widening a vessel in the human body formed of a plurality of essentially triangular cells comprising:

a plurality of first circumferential bands consisting essentially of a basically sinusoidal pattern of loops at a first frequency,

a plurality of second circumferential bands consisting essentially of a basically sinusoidal pattern of loops at a second frequency higher than said first frequency, alternating with said first circumferential bands and periodically coupled thereto to form the triangular cells;

wherein the circumferential bands have legs that are oriented along the longitudinal axis of the stent and at least one leg of one of the circumferential band is shorter than another leg of the same circumferential band; and

wherein the first circumferential bands have wider legs than the second circumferential bands.

50. A stent according to claim 49 wherein the first circumferential bands containing a pattern of loops comprise:

even first circumferential bands containing a pattern of loops; and

odd first circumferential bands containing a pattern of loops which are 180□

out of phase with the loops of the even first circumferential bands, an odd first circumferential band occurring between every two even first circumferential bands.

51. A stent according to claim 49, wherein each cell includes two loops of one of said plurality of first circumferential bands and three loops of one of said plurality of second circumferential bands.

52. A stent according to claim 49, wherein each cell includes a number of loops of said first circumferential band corresponding to two cycles of said first frequency and a number of loops of said second circumferential band corresponding to three cycles of said second frequency.

53. A stent according to claim 52, wherein the higher frequency of the loops in said second circumferential bands provide improved flexibility.

54. A stent according to claim 53, wherein, while flexing, elements in the higher frequency loops have maximal strain that is lower than the elastic limit of the material of the stent.

55. A stent according to claim 49, wherein the first circumferential bands have loops forming two cycles per cell.

56. A stent according to claim 49, wherein the second circumferential bands have loops forming three cycles per cell.