Methods for the manufacture of radially expansible stents

• US 5,907,893 A
• Filed: 01/31/1997
• Issued: 06/01/1999
• Est. Priority Date: 01/30/1996
• Status: Expired due to Term

• Current Assignee: Medtronic Ave Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Turovskiy, Roman, Gittings, Darin C., Cox, Brian J., Shiu, Brian, Zadno-Azizi, Gholam-Reza, Luehrs, Kirsten F., Hayes, Michael B., Coombs, Craig J.
• Primary Examiner(s): Bryant, David P.
• Application Number:
  US08/791,921
• Time in Patent Office: 851 Days
• Field of Search: 29/6.1, 29/6.2, 29/412, 29/418, 72/379.2, 623/1, 623/12, 623/900, 623/901, 606/194
• US Class Current: 29/6.1
• 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 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2230/0017 Angular shapes
• CPC Class Codes: A61F 2230/005 Rosette-shaped, e.g. star-shaped
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2230/0067 conical
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: B21D 51/10 conically or cylindrically shaped objects
• CPC Class Codes: Y10S 623/901 Method of manufacturing prosthetic device
• CPC Class Codes: Y10T 29/18 Expanded metal making
• CPC Class Codes: Y10T 29/49789 Obtaining plural product pieces from unitary workpiece
• CPC Class Codes: Y10T 29/49799 Providing transitory integral holding or handling portion
• CPC Class Codes: Y10T 29/49995 Shaping one-piece blank by removing material

Abstract

Methods and articles for fabricating expansive stents having generally cylindrical configurations with a pattern therein include interconnecting portions from a generally planar sheet of material with a central portion. A pattern is formed in the sheet of material around said central portion corresponding to said pattern having interconnecting portions. The pattern has a generally circular outer margin. The pattern is separated from the sheet of material and causes relative movement between the central portion of the pattern and the outer circular margin in a direction perpendicular to the plane of the central portion. The pattern is transformed from one sheet form into one in cylindrical form to provide an expansible stent having a generally cylindrical configuration.

Claims

1. A method for fabricating a cylindrical stent, said method comprising:

providing a planar network of interconnected elements comprising an annular lattice; and

reforming the planar network into a cylindrical wall.

2. A method as in claim 1, wherein the interconnected elements of the planar network are joined in at least one continuous annular path.

3. A method as in claim 2, wherein the interconnected elements comprise an annular serpentine ring.

4. A method as in claim 1, wherein the interconnected elements comprise a plurality of closed peripheral structures.

5. A method as in claim 4, wherein the closed peripheral structures are polygonal.

6. A method as in claim 5, wherein the polygonal structures are lozenge-shaped.

7. A method as in claim 1, wherein the planar network comprises a spiral with a radially inward end and a radially outward end.

8. A method as in claim 7, wherein the spiral has a superimposed serpentine pattern.

9. A method as in claim 7, wherein the spiral has a rectilinear geometry.

10. A method as in claim 1, wherein the providing step comprises patterning a planar sheet of material.

11. A method as in claim 10, wherein the patterning step comprises photochemical etching of the planar sheet of material.

12. A method as in claim 10, wherein the patterning step comprises cutting the sheet of material.

13. A method as in claim 12, wherein the cutting step comprises electrical discharge machining.

14. A method as in claim 12, wherein the cutting step comprises laser cutting.

15. A method as in claim 12, wherein the cutting step comprises providing a plurality of planar sheets arranged in a stack and cutting the stack to provide a plurality of planar networks.

16. A method as in claim 10, wherein the patterning step comprises stamping the planar sheet of material.

17. A method as in claim 1, wherein the providing step comprises folding a continuous filament into the planar network or joining multiple discrete elements together.

18. A method as in claim 1, wherein the providing step comprises joining a plurality of discrete elements into the planar network.

19. A method a s in claim 1, wherein the planar network of interconnected elements is composed of a metal.

20. A method as in claim 19, wherein the metal is a shape memory alloy.

21. A method as in claim 20, wherein the metal is a nickel titanium alloy.

22. A method as in claim 19, wherein the metal is selected from the group consisting of stainless steel, titanium, tantalum, platinum, and elgiloy.

23. A method as in claim 1, further comprising treating the reformed cylindrical wall to change at least one physical property.

24. A method as in claim 23, wherein the treating step comprises heat treating.

25. A method for fabricating a cylindrical stent, said method comprising;

providing an annular lattice of interconnected elements, said lattice being eversible; and

everting the annular lattice to form a cylindrical wall of the cylindrical stent, wherein the resulting everted structure is radially expansible.

26. A method as in claim 25, wherein the interconnected elements of the planar network are joined in at least one continuous annular path.

27. A method as in claim 26, wherein the interconnected elements comprise an annular serpentine ring.

28. A method as in claim 25, wherein the annular lattice comprises an annular serpentine ring which becomes a cylindrical serpentine ring after eversion.

29. A method as in claim 25, wherein the interconnected elements comprise a plurality of closed peripheral structures.

30. A method as in claim 29, wherein the closed peripheral structures are polygonal.

31. A method as in claim 30, wherein the polygonal structures are lozenge-shaped.

32. A method as in claim 31, wherein the annular lattice comprises a plurality of lozenge-shaped elements having axes which are aligned radially within the annular network, wherein adjacent lozenge-shaped elements are connected to each other.

33. A method as in claim 32, wherein the adjacent lozenge-shaped elements are connected to each other by tabs located along a common diametric line within the annular lattice.

34. A method as in claim 33, wherein the annular lattice comprises at least two radially successive annular rows of lozenge-shaped elements.

35. A method as in claim 25, wherein the providing step comprises patterning a planar sheet of material.

36. A method as in claim 35, wherein the patterning step comprises photochemical etching of the planar sheet of material.

37. A method as in claim 35, wherein the patterning step comprises cutting the sheet of material.

38. A method as in claim 37, wherein the cutting step comprises electrical discharge machining.

39. A method as in claim 37, wherein the cutting step comprises laser cutting.

40. A method as in claim 37, wherein the cutting step comprises providing a plurality of planar sheets arranged in a stack and cutting the stack to provide a plurality of planar networks.

41. A method as in claim 35, wherein the patterning step comprises stamping the planar sheet of material.

42. A method as in claim 25, wherein the providing step comprises folding a continuous filament into the annular lattice.

43. A method as in claim 25, wherein the providing step comprises joining a plurality of discrete elements into the annular lattice.

44. A method as in claim 25, wherein the annular lattice of interconnected elements is composed of a metal.

45. A method as in claim 44, wherein the metal is a shape memory alloy.

46. A method as in claim 45, wherein the metal is a nickel titanium alloy.

47. A method as in claim 44, wherein the metal is selected from the group consisting of stainless steel, titanium, tantalum, platinum, and elgiloy.

48. A method as in claim 25, further comprising treating the everted cylindrical wall to change at least one physical property.

49. A method as in claim 48, wherein the treating step comprises heat treating.

50. A method for fabricating a cylindrical stent, said method comprising:

providing an eversible structure which has been patterned in a planar sheet of material, said eversible structure comprising a central portion and an outer margin; and

everting the eversible structure to form a cylindrical wall of the cylindrical stent, wherein the everting step comprises relative movement between the central portion and the outer margin and wherein the resulting cylindrical wall is radially expansible.

51. A method as in claim 50, wherein the eversible structure comprises an annular lattice.

52. A method as in claim 51, wherein the eversible structure comprises interconnected elements which are joined in at least one continuous annular path.

53. A method as in claim 52, wherein the interconnected elements comprise an annular serpentine ring.

54. A method as in claim 50, wherein the eversible structure is an annular serpentine ring which becomes a cylindrical serpentine ring after eversion.

55. A method as in claim 50, wherein the interconnected elements comprise a plurality of closed peripheral structures.

56. A method as in claim 55, wherein the closed peripheral structures are polygonal.

57. A method as in claim 56, wherein the polygonale structures are lozenge-shaped.

58. A method as in claim 57, wherein the eversible structure comprises a plurality of lozenge-shaped elements having axes which are aligned radially, wherein adjacent lozenge-shaped elements are connected to each other.

59. A method as in claim 58, wherein the adjacent lozenge-shaped elements are connected to each other by tabs located along a common diametric line.

60. A method as in claim 59, wherein the eversible structure comprises at least two radially spaced-apart annular rows of diamond-shaped elements.

61. A method as in claim 50, wherein the eversible structure comprises a spiral with a radially inward end and a radially outward end, wherein the spiral becomes a radially expansible helical coil after eversion.

62. A method as in claim 61, wherein the spiral has a superimposed serpentine pattern.

63. A method as in claim 61, wherein the spiral has a rectilinear geometry.

64. A method as in claim 50, wherein the providing step comprises patterning a planar sheet of material.

65. A method as in claim 64, wherein the patterning step comprises photochemical etching of the planar sheet of material.

66. A method as in claim 64, wherein the patterning step comprises cutting the sheet of material.

67. A method as in claim 66, wherein the cutting step comprises electrical discharge machining.

68. A method as in claim 66, wherein the cutting step comprises laser cuttings.

69. A method as in claim 66, wherein the cutting step comprises providing a plurality of planar sheets arranged in a stack and cutting the stack to provide a plurality of planar networks.

70. A method as in claim 50, wherein the patterning step comprises stamping the planar sheet of material.

71. A method as in claim 50, wherein the planar network of interconnected elements is composed of a metal.

72. A method as in claim 71, wherein the metal is a shape memory alloy.

73. A method as in claim 72, wherein the metal is a nickel titanium alloy.

74. A method as in claim 71, wherein the metal is selected from the group consisting of stainless steel, titanium, tantalum, platinum, and elgiloy.

75. A method as in claim 50, further comprising treating the everted cylindrical wall to change at least one physical property.

76. A method as in claim 75, wherein the treating step comprises heat treating.

77. A method for making an expansible stent having a generally cylindrical configuration with a pattern therein having interconnecting portions from a generally planar sheet of material having a central portion comprising forming around said central portion a pattern in the sheet of material corresponding to said pattern having interconnecting portions, the pattern having a generally circular outer margin, separating the pattern from the sheet of material and causing relative movement between the central portion of the pattern and the outer circular margin in a direction perpendicular to the plane of the central portion to transform the pattern from one in sheet form into one in cylindrical form to provide the expansible stent having a generally cylindrical configuration.

78. A method as in claim 77, wherein said pattern is a first pattern, and further comprising forming a second pattern in said sheet of material adjacent said first pattern, said first and second patterns having an interconnecting portion therebetween to provide, upon transformation of said first and second patterns from sheet form to cylindrical form, a pair of axially aligned stents interconnected by said interconnecting portion.

79. A method as in claim 77, wherein the pattern has a central opening in the central portion, the transformation from sheet form to cylindrical form being accomplished by causing relative movement between a tapered mandrel and the pattern and causing the tapered portion of the mandrel to extend through the central opening to progressively cause the pattern to be transformed from a planar sheet into a substantially conical shape and thereafter into a cylindrical shape to provide a stent having a diameter generally corresponding to the diameter of the mandrel.

80. A method as in claim 79, further comprising heat treating the stent after it has been formed into a cylindrical shape on the mandrel.

81. A method as in claim 80, further comprising positioning a sleeve over the mandrel to hold the stent in place and to provide a maximum diameter for the stent during the time it is being heat treated.

82. A method as in claim 80, wherein the sheet of material is formed of a nickel titanium alloy and wherein heat treating is carried out at a temperature ranging from 350°

C. to 500°

C. for a period of time ranging from a few seconds to 60 minutes.

83. A method as in claim 80, further comprising compressing the stent to a smaller diameter after the stent has been heat treated to create a stent having a length which is greater than the diameter of the stent.

84. A method as in claim 77, wherein said central portion of the pattern has a solid central portion and wherein causing relative movement between the central portion and the outer circular margin comprises engaging a punch against said central portion to cause a transformation of material from a planar sheet by deep drawing into a cylindrical cup.

85. A method as in claim 84, together with the step of severing the central portion of the pattern from the cylindrical cup after it has been formed and separating the cylindrical cup from the sheet.

86. A method for making an expansible stent having a generally cylindrical configuration from a sheet of material, said method comprising forming a cylindrical cup having a bottom from the sheet of material, severing the bottom from the cylindrical cup and severing the cup from the sheet.

87. A method as in claim 86, together with the step of forming a pattern having interconnecting portions therein in the material forming the cup.

88. A method as in claim 87, wherein the pattern is formed in the sheet prior to the formation of the cup.

89. A method as in claim 87, wherein the pattern is formed in the cup after formation of the cup.

90. A method for fabricating a cylindrical stent, said method comprising:

providing a planar network of interconnected elements having a central portion and an outer margin; and

everting the planar network into a cylindrical wall by moving the central portion relative to the outer margin.

91. A method as in claim 90, wherein the planar network comprises an annular lattice.

92. A method as in claim 91, wherein the interconnected elements of the planar network are joined in at least one continuous annular path.

93. A method as in claim 92, wherein the interconnected elements comprise an annular serpentine ring.

94. A method as in claim 91, wherein the interconnected elements comprise a plurality of closed peripheral structures.

95. A method as in claim 94, wherein the closed peripheral structures are polygonal.

96. A method as in claim 95, wherein the polygonal structures are lozenge-shaped.

97. A method as in claim 90, wherein the planar network comprises a spiral with a radially inward end and a radially outward end.

98. A method as in claim 97, wherein the spiral has a superimposed serpentine pattern.

99. A method as in claim 97, wherein the spiral has a rectilinear geometry.

100. A method as in claim 90, wherein the providing step comprises patterning a planar sheet of material.

101. A method as in claim 100, wherein the patterning step comprises photochemical etching of the planar sheet of material.

102. A method as in claim 100, wherein the patterning step comprises cutting the sheet of material.

103. A method as in claim 102, wherein the cutting step comprises electrical discharge machining.

104. A method as in claim 102, wherein the cutting step comprises laser cutting.

105. A method as in claim 102, wherein the cutting step comprises providing a plurality of planar sheets arranged in a stack and cutting the stack to provide a plurality of planar networks.

106. A method as in claim 90, wherein the patterning step comprises stamping the planar sheet of material.

107. A method as in claim 90, wherein the providing step comprises folding a continuous filament into the planar network or joining multiple discrete elements together.

108. A method as in claim 90, wherein the providing step comprises joining a plurality of discrete elements into the planar network.

109. A method as in claim 90, wherein the planar network of interconnected elements is composed of a metal.

110. A method as in claim 109, wherein the metal is a shape memory alloy.

111. A method as in claim 110, wherein the metal is a nickel titanium alloy.

112. A method as in claim 109, wherein the metal is selected from the group consisting of stainless steel, titanium, tantalum, platinum, and elgiloy.

113. A method as in claim 90, further comprising treating the reformed cylindrical wall to change at least one physical property.

114. A method as in claim 113, wherein the treating step comprises heat treating.