Compliant blood vessel graft

• US 20070293932A1
• Filed: 05/04/2007
• Published: 12/20/2007
• Est. Priority Date: 04/28/2003
• Status: Active Grant

• Current Assignee: Vascular Graft Solutions Ltd.
• Original Assignee: Kips Bay Medical, Inc.
• Inventors: Wolf, Michael, Douk, Nareak, Rafiee, Nasser, Bezuidenhout, Deon, Yeoman, Mark, Bowles, Hellmut, Zilla, Peter, Franz, Thomas, Human, Paul
• Granted Patent: US 7,998,188 B2
• Time in Patent Office: Days
• US Class Current: 623/1.11
• CPC Class Codes: A61B 17/11 for performing anastomosis; Buttons for anastomosis
• CPC Class Codes: A61B 2017/1107 for blood vessels
• CPC Class Codes: A61B 2017/1132 End-to-end connections
• CPC Class Codes: A61B 2017/1135 End-to-side connections, e.g. T- or Y-connections Y-shaped blood vessel prostheses A61F2002/065
• CPC Class Codes: A61B 2017/1139 Side-to-side connections, e.g. shunt or X-connections
• CPC Class Codes: A61B 5/1076 for measuring dimensions inside body cavities, e.g. using catheters A61B3/1005 takes precedence
• CPC Class Codes: A61F 2/06 Blood vessels
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: A61F 2/856 Single tubular stent with a side portal passage
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/95 Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61F 2240/002 Designing or making customized prostheses

Abstract

Stents and methods of using stents are provided. Stents of the invention provide external support structure for a blood vessel segment disposed within, wherein the stents are capable of resilient radial expansion in a manner mimicking the compliance properties of an artery. The stent may be formed of a knitted or braided mesh formed so as to provide the needed compliance properties. A venous graft with the stent and a vein segment disposed within is provided, wherein graft is capable of mimicking the compliance properties of an artery. Methods of selecting stents for downsizing and methods of using the stents of the invention in downsizing and smoothening are provided. Methods of replacing a section of an artery with a venous graft including a stent of the invention are provided. Methods of reducing intimal hyperplasia in implanted vein segment in a venous graft using stents of the invention are provided.

Claims

1. A flexible, resilient, generally tubular external support within which may be supported a vein segment to form a venous graft mimicking the compliance properties of a healthy artery, the tubular support being capable of resilient radial expansion in a manner providing compliance in the range of 3 to 30%/100 mm Hg.

2. The tubular external support of claim 1, wherein said support comprises a knit wire mesh.

3. The tubular external support of claim 2, wherein the knit wire mesh comprising loops that alternate in size circumferentially of the support

4. The tubular external support of claim 1, wherein said support comprises a braided wire mesh including an element for controlling the degree of axial extension of the support.

5. The tubular external support of claim 4, wherein said element comprises a thread attached to and carried internally of the support.

6. The tubular external support of claim 1, including a vein segment carried within the support, the vein segment having an ablumenal surface in contact with, and supported by, said tubular support.

7. A venous graft for replacement of a section of an artery, the graft comprising a flexible, resilient, generally tubular external support and a vein segment carried within and having an ablumenal surface in contact with and supported by the tubular support, the venous graft being capable of resilient radial expansion in a manner mimicking the compliance properties of an artery.

8. The venous graft of claim 7, wherein said tubular support is capable of said resilient radial expansion without significant axial dimensional changes.

9. The venous graft of claim 7, wherein the compliance of the graft ranges from 3 to 30%/100 mm Hg.

10. The venous graft of claim 7, wherein the external support comprises a generally tubular fiber mesh capable of expanding in diameter through resilient movement of wires of the mesh to accommodate radial expansion of the vein segment supported in it sufficient to provide the graft with said compliance.

11. The venous graft of claim 7, wherein said external support comprises a knit, tubular mesh capable of expanding radially to accommodate radial expansion of the vein segment supported in it within said compliance range.

12. The venous graft of claim 7, wherein said external support comprises a braided fiber mesh so configured as to exhibit radial expansion in said compliance range without significant reduction in the axial length of the support.

13. The venous graft of claim 10, wherein said mesh is made of metal wire.

14. The venous graft of claim 13, wherein said metal wire is of stainless steel or of a cobalt chrome alloy.

15. The venous graft of claim 13, wherein said metal wire is a shape memory alloy.

16. The venous graft of claim 10, wherein said mesh is polymeric.

17. The venous graft of claim 7, wherein the ablumenal surface of the vein segment is bonded to said tubular support.

18. The venous graft of claim 7, wherein the vein segment and the tubular support are axially coextensive.

19. The venous graft of claim 11, wherein said knitted tubular fiber mesh is made from crimped fibers.

20. The venous graft of claim 10, wherein said tubular fiber mesh is made from fibers that are crimped after having been formed into said tubular mesh.

21. A venous graft for replacement of a section of an artery, the graft comprising a flexible, resilient, knit wire mesh configured as a generally tubular external support and a vein segment carried within and having an ablumenal surface in contact with and supported by the tubular support, the support having resilient radial expansion and contraction characteristics that provide the venous graft with compliance properties mimicking those of an artery.

22. The venous graft of claim 21, wherein the compliance of the venous graft ranges from 3 to 30%/100 mm Hg.

23. A method of producing a venous graft for use in replacing a section of an artery, comprising providing a segment of a vein and sheathing the segment in a generally tubular support in supportive contact with the ablumenal surface of the vein segment, the support being sufficiently flexible and radially resilient as to provide the graft with compliance properties mimicking the compliance properties of an artery.

24. The method of claim 23, further comprising cutting said venous graft from a longer section of vein sheathed in said tubular support, the ends of the vein and tubular support of the venous graft being coextensive.

25. The method of claim 23, further comprising supporting said generally tubular support upon an exterior surface of an applicator having an internal passage within which is positioned the vein segment, and removing the applicator to permit the tubular support to come into supportive contact with the ablumenal surface of the vein segment.

26. The method of claim 23, further comprising supporting said generally tubular support upon an exterior surface of an applicator having an internal passage, and, while passing the vein segment from within the applicator passage, drawing the tubular support onto the surface of the vein segment.

27. The method of claim 23, wherein said generally tubular support is chosen to be sufficiently radially resilient as to provide the venous graft with a compliance ranging from 3 to 30%/100 mm Hg.

28. The method of claim 25, wherein said tubular support is axially resilient, the method including the step of controlling axial dimension changes of the tubular support as the support comes into supportive contact with the vein segment to provide the venous graft with said compliance properties.

29. The method of claim 28, further comprising including the step of providing the tubular support with an axially extending, relatively inextensible element that restrains the tubular support from unwanted axial extension.

30. The method of claim 29, wherein said inextensible element comprises a flexible fiber positioned within the tubular support and between the tubular support and the ablumenal surface of the vein segment.

31. The method of claim 29, wherein the flexible fiber is a wire joined to the interior of the tubular support.

32. The method of claim 23, further comprising bonding the ablumenal surface of the vein segment to the tubular support.

33. The method of claim 23, further comprising forming said tubular support from a knit wire mesh, wherein said mesh is formed with loops that alternate in size circumferentially of the support.

34. A method of producing a blood vessel graft comprising providing a segment of a blood vessel and sheathing the segment in a generally tubular support in supportive contact with the ablumenal surface of the vessel segment, the support being sufficiently flexible and radially resilient as to contribute to the compliance properties of the graft.

35. The method of claim 34, further comprising supporting the generally tubular support on the exterior surface of an introducer tube, sliding the introducer tube over the vessel segment, and removing the introducer tube to enable the tubular support to contact the ablumenal surface of the vessel.

36. The method of claim 34, further comprising affixing a cord to one end of the vessel segment, and maintaining tension on the vessel segment during sheathing of the vessel segment within the tubular support.

37. The method of claim 36, wherein the cord comprises a plug frictionally received within the introducer tube, the method including withdrawing the introducer tube from the vessel segment and tubular support, friction between the tube and plug maintaining the vessel in tension during such withdrawal.

38. A blood vessel graft comprising a flexible, mesh configured as a generally tubular external support and a blood vessel segment carried within and having an ablumenal surface in contact with and supported by the tubular support, the support having resilient radial expansion and contraction characteristics contributing to the compliance properties of the graft.

39. The graft of claim 38, further comprising an adhesive adhering the tubular support to the ablumenal surface of the vessel to resist collapse of the vessel within the support.

40. The graft of claim 38, further comprising an adhesive tape positioned around a portion of the tubular support, the tape including an adhesive that extends through the fiber mesh support and into adhesive contact with the ablumenal surface of the vessel.

41. The graft of claim 39, wherein said adhesive at least partially embeds said fiber mesh and adhesively contacts the ablumenal surface of the vessel.

42. The graft of claim 39, wherein said adhesive is formed as a coating on the fibers of the fiber mesh.

43. The graft of claim 38, wherein said vessel segment is of porcine or bovine origin.

44. A method of attachment of the graft of claim 40 to another blood vessel, the method comprising cutting said portion of the graft bearing said adhesive tape to conform to the wall of the other blood vessel, the adhesive tape maintaining the cut end of the graft open and preventing fraying of the cut end.

45. The method of claim 44, wherein the graft is cut on the bias.

46. A method of applying an adhesive tape to the exterior surface of a vessel graft that includes a vessel segment supported within a flexible, elastic fiber mesh tubular support, the method comprising compressing the graft between lengths of adhesive tape having an adhesive that penetrates the mesh to adhesively contact the ablumenal surface of the vessel, and allowing the graft to resume its tubular configuration.

47. The method of claim 46, further comprising positioning the tape lengths in a deformable clip, inserting a segment of the stent in the clip between the tape lengths, deforming the clip to compress and flatten the stent, and removing the clip.

48. A graft for replacement of a section of an artery, the graft comprising a flexible, resilient, knit wire mesh configured as a generally tubular external support and a blood vessel segment carried within and having an ablumenal surface in contact with and supported by the tubular support, the support having resilient radial expansion and contraction characteristics that provide the graft with compliance properties mimicking those of an artery.

49. A method for selecting a stent for a venous graft, the method comprising:

measuring a minimum diameter and a maximum diameter of a vein;

selecting a maximum amount of downsizing for the vein and a minimum amount of downsizing for the vein;

calculating a range of diameters of stents that provide the an amount of downsizing between the selected maximum amount and the selected minimum amount;

selecting a single stent having a diameter that falls within the calculated range.

50. The method according to claim 49, further comprising calculating a degree of downsizing for smoothening the vein.

51. The method according to claim 50, wherein said smoothening comprises altering an outside diameter of at least one part of the vein to be substantially the same as another part of the vein.

52. The method according to claim 49, wherein the single stent is the smallest possible stent within the range, resulting in maximum downsizing.

53. The method according to claim 49, wherein the single stent is the largest possible stent within the range, resulting in minimum downsizing.

54. The method according to claim 49, wherein the stent has a diameter of between about 2.7 mm and about 4.0 mm.

55. The method according to claim 53, wherein the stent has a diameter of between about 3.0 mm and 4.0 mm.

56. The method according to claim 49, wherein the maximum amount of downsizing for the vein is the degree of downsizing for substantially smoothening the vein.

57. The method according to claim 56, wherein said substantially smoothening the vein includes smoothening irregularities in the vein.

58. A stent comprising:

a generally tubular member constructed and arranged to receive a harvested vein, the generally tubular member being compliant so as to contract and expand with the vein, the tubular member having an inner diameter between about 2.7 mm and about 4.0 mm.

59. The stent according to claim 58, wherein the inner diameter is between about 3.0 mm and about 4.0 mm.

60. The stent according to claim 58, wherein the generally tubular member comprises a knitted structure.

61. The stent according to claim 60, wherein the knitted structure comprises a metal wire.

62. The stent according to claim 60, wherein the knitted structure comprises a polymeric material.

63. The stent according to claim 62, wherein the polymeric material comprises an elastomeric polymer.

64. The stent according to claim 60, wherein the knitted structure is configured to be shrinkable after receiving the harvested vein.

65. The stent according to claim 58, wherein the generally tubular member comprises a plurality of connected rings.

66. The stent according to claim 65, wherein the rings are interconnected.

67. The stent according to claim 66, wherein the rings are connected on outside surfaces of the rings.

68. A stent delivery device comprising:

a stent constructed and arranged to receive a vein segment, the stent being compliant so as to contract and expand with the vein; and

a delivery tube comprising a coating configured to impart slip properties to the tube to reduce traumatic introduction of the stent to an outside surface of the vein.

69. A method of stabilizing a vein segment in a venous graft, the method comprising:

providing the vein segment;

disposing the vein segment within a lumen of a stent constructed and arranged to contract and expand with the vein segment, the stent having an inner diameter between about 2.7 mm and about 4.0 mm.

70. The method according to claim 69, wherein the stent comprises a knitted structure.

71. The method according to claim 70, wherein the knitted structure comprises a metal wire.

72. The method according to claim 69, wherein the knitted structure comprises a polymeric material.

73. The method according to claim 69, further comprising shrinking the stent after said disposing the vein segment within the lumen of the stent to smoothen irregularities in the vein segment.

74. A method for replacing a section of an artery in a patient with a venous graft capable of resilient radial expansion in a manner mimicking the compliance properties of a healthy artery in a patient comprising:

restricting blood flow through said section of artery to be replaced;

excising said section of said artery to be replaced, leaving a first available artery end and a second available artery end in the patient;

providing a vein segment having a first vein segment end and a second vein segment end;

joining said first vein segment end to said first available artery end;

providing a flexible, resilient, generally tubular external support stent capable of resilient radial expansion in a manner providing compliance in the range of 3 to 30%/100 mm Hg;

sheathing said vein segment with said stent by introducing said second vein segment end into said stent and sliding said stent over the ablumenal surface of said vein segment until substantially all of said vein segment is carried within said stent; and

joining the second vein segment end to the second available artery end provide said venous graft,

wherein said venous graft is capable of resilient radial expansion in a manner mimicking the compliance properties of a healthy artery when blood flow is restored to said artery.

75. The method of claim 74, wherein said stent is capable of said resilient radial expansion without significant axial dimensional changes.

76. The method of claim 74, wherein said stent comprises a generally tubular fiber mesh capable of expanding in diameter through resilient movement of fibers of the mesh to accommodate radial expansion of the vein segment supported in it sufficient to provide the venous graft with said compliance.

77. The method of claim 76, wherein said stent comprises a knit, tubular mesh capable of expanding radially to accommodate radial expansion of the vein segment supported in it, within said compliance range.

78. The method of claim 76, wherein said stent comprises a braided fiber mesh so configured as to exhibit radial expansion in said compliance range without significant reduction in the axial length of the stent.

79. The method of claim 76, wherein said fiber mesh is made of metal wire.

80. The method of claim 79, wherein said metal wire is a shape memory alloy.

81. The method of claim 76, wherein said fiber mesh is polymeric.

82. The method of claim 74, wherein said ablumenal surface of said vein segment is bonded to said stent.

83. A method for reducing intimal hyperplasia in an implanted vein segment following replacement of a section of an artery with a implantation of a venous graft comprising a providing venous graft comprising a flexible, resilient, generally tubular external support stent and said vein segment carried within said stent, said vein segment having an ablumenal surface in contact with and supported by said stent, wherein said venous graft is capable of resilient radial expansion in a manner mimicking the compliance properties of a healthy artery when blood flows through the venous graft under physiological conditions.

84. The method of claim 83, said stent support being capable of resilient radial expansion in a manner providing compliance in the range of 3 to 30%/100 mm Hg.

85. The method of claim 84, wherein said stent is capable of said resilient radial expansion without significant axial dimensional changes.

86. The method of claim 84, wherein said stent comprises a generally tubular fiber mesh capable of expanding in diameter through resilient movement of fibers of the mesh to accommodate radial expansion of the vein segment supported in it sufficient to provide the venous graft with said compliance range.

87. The method of claim 86, wherein said stent comprises a knit, tubular mesh capable of expanding radially to accommodate radial expansion of the vein segment supported in it, within said compliance range.

88. The method of claim 86, wherein said stent comprises a braided fiber mesh so configured as to exhibit radial expansion in said compliance range without significant reduction in the axial length of the stent.

89. The method of claim 88, wherein the lumen diameter of said implanted vein segment does not increase significantly over time.

90. The method of claim 86, wherein said fiber mesh is made of metal wire.

91. The method of claim 90, wherein said metal wire is a shape memory alloy.

92. The method of claim 86, wherein said fiber mesh is polymeric.

93. The method according to claim 83, further comprising shrinking the stent after said disposing the vein segment within the lumen of the stent to smoothen irregularities in the vein segment.

94. The method of claim 83, further comprising selecting a stent for the venous graft, the method further comprising:

measuring a minimum diameter and a maximum diameter of a vein from which said vein segment will harvested;

selecting a maximum amount of downsizing for said vein and a minimum amount downsizing for said vein;

calculating a range of diameters of stents that provide the amount of downsizing between said selected maximum amount and the selected minimum amount;

selecting a single stent having a diameter that falls within said calculated range.

95. The method according to claim 94, wherein the stent has a diameter of between about 2.7 mm and about 4.0 mm.

96. The method according to claim 95, wherein the stent has a diameter of between about 3.0 mm and 4.0 mm.