Implantable medical devices

• US 20050216074A1
• Filed: 10/05/2004
• Published: 09/29/2005
• Est. Priority Date: 10/11/2002
• Status: Active Grant

• Current Assignee: University of Connecticut (State of Connecticut)
• Original Assignee: University of Connecticut (State of Connecticut)
• Inventors: Sahatjian, Ronald A., Mather, Patrick T., Tan, Francisca, Liu, Changdeng, Campo, Cheryl J.
• Granted Patent: US 7,794,494 B2
• Time in Patent Office: Days
• US Class Current: 623/1.110
• 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 2002/8483 Barbs
• CPC Class Codes: A61F 2002/91541 Adjacent bands are arranged out of phase
• CPC Class Codes: A61F 2002/9528 for retrieval of stents
• CPC Class Codes: A61F 2220/0016 with sharp anchoring protrusions, e.g. barbs, pins, spikes
• CPC Class Codes: A61F 2250/0039 differing in diameter
• CPC Class Codes: A61F 2250/0068 the pharmaceutical product being in a reservoir
• CPC Class Codes: A61L 29/14 Materials characterised by their function or physical properties , e.g. lubricating compositions
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61M 25/1027 Making of balloon catheters
• CPC Class Codes: C08G 18/3893 containing silicon
• CPC Class Codes: C08G 18/4277 Caprolactone and/or substituted caprolactone
• CPC Class Codes: C08G 18/4833 Polyethers containing oxyethylene units
• CPC Class Codes: C08G 2230/00 Compositions for preparing biodegradable polymers
• CPC Class Codes: C08G 61/08 of carbocyclic compounds containing one or more carbon-to-carbon double bonds in the ring
• CPC Class Codes: C08L 65/00 Compositions of macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain C08L7/00 - C08L57/00, C08L61/00 take precedence; Compositions of derivatives of such polymers

Abstract

A medical device includes a balloon catheter having an expandable member, e.g., an inflatable balloon, at its distal end and a stent or other endoprosthesis. The stent is, for example, an apertured tubular member formed of a polymer and is assembled about the balloon. The stent has an initial diameter for delivery into the body and can be expanded to a larger diameter by inflating the balloon.

Claims

1. A product comprising a balloon catheter having an expandable member and a stent mounted on the expandable member, the stent comprising an apertured tubular member formed of a polymer, the stent having an initial diameter for delivery into a body lumen and which can be expanded to a second diameter in the lumen by expanding the expandable member, wherein during expansion the polymer does not substantially flow and substantial stress relaxation or creep does not occur so that the geometry of the tubular member is maintained.

2. The product of claim 1, wherein the polymer exhibits a plateau in its plot of storage modulus as a function of temperature.

3. The product of claim 1, wherein the polymer has a melt temperature from about 40°

C. to about 50°

C.

4. The product of claim 1, wherein the polymer has a melt temperature range of less than about 5°

C.

5. The product of claim 1, wherein the polymer has a glass transition temperature from about 40°

C. to about 50°

C.

6. The product of claim 1, wherein the polymer has a glass transition temperature range of less than about 5°

C.

7. The product of claim 1, wherein the polymer is elastomeric at room temperature.

8. The product of claim 1, wherein the polymer is bioabsorbable.

9. The product of claim 1, wherein the polymer is crosslinked.

10. The product of claim 9, wherein the polymer is radiation crosslinked.

11. The product of claim 9, wherein the polymer is chemically crosslinked.

12. The product of claim 1, wherein the polymer is a shape memory polymer.

13. The product of claim 1, wherein the polymer is selected from the group consisting of polynorbomene, polycaprolactone, polyenes, nylons, polycyclooctene (PCO), blends of PCO and styrene-butadiene rubber, polyvinyl acetate/polyvinylidinefluoride (PVAc/PVDF), blends of PVAc/PVDF/polymethylmethacrylate (PMMA), polyurethanes, styrene-butadiene copolymers, polyethylene, trans-isoprene, blends of polycaprolactone and n-butylacrylate, POSS polyurethane polymers and blends thereof.

14. The polymer of claim 1, wherein the wherein the polymer includes an additive selected from the group consisting of drugs, radiopaque agents and magnetic heating agents.

15. The product of claim 1, wherein the initial diameter is from about 1 mm to about 5 mm.

16. The product of claim 1, wherein the expanded diameter is from about 1 mm to about 20 mm.

17. The product of claim 1, wherein the expanded diameter is from about 100% to about 400% the initial diameter.

18. The product of claim 1, wherein the apertured tubular member is formed from a plurality of filaments, the plurality of filaments forming a tubular structure.

19. The product of claim 1, wherein the ratio of apertured open area to total area of the tubular member is greater than about 0.5.

20. The product of claim 1, wherein the apertures are diamond-like openings.

21. A product comprising a tubular endoprosthesis having a body formed of a polymer, the endoprosthesis being designed for delivery into a body lumen, wherein when the endoprosthesis is expanded in the lumen under conditions of expanding pressure and temperature, the wall thickness of the body is substantially maintained.

22. The product of claim 21, wherein a change in the wall thickness is less than about 1%.

23. The implantable medical device of claim 21, wherein the wall thickness is from about 0.005 mm to about 5 mm.

24. The product of claim 21, wherein the polymer is selected from the group consisting of polynorbomene, polycaprolactone, polyenes, nylons, polycyclooctene (PCO), blends of PCO and styrene-butadiene rubber, polyvinyl acetate/polyvinylidinefluoride (PVAc/PVDF), blends of PVAc/PVDF/polymethylmethacrylate (PMMA), polyurethanes, styrene-butadiene copolymers, polyethylene, trans-isoprene, blends of polycaprolactone and n-butylacrylate, POSS polyurethanes and blends thereof.

25. The product of claim 21, wherein the polymer has a melt temperature from about 40°

C. to about 50°

C.

26. The product of claim 21, wherein the polymer has a glass transition temperature from about 40°

C. to about 60°

C.

27. The product of claim 21, wherein the polymer is bioabsorbable.

28. The product of claim 21, wherein the polymer is crosslinked.

29. The product of claim 28, wherein the polymer is radiation crosslinked.

30. The product of claim 28, wherein the polymer is chemically crosslinked.

31. The product of claim 21, wherein the polymer is a shape memory polymer.

32. The product of claim 21, wherein the polymer exhibits a plateau in its plot of storage modulus as a function of temperature.

33. The polymer of claim 21, wherein the wherein the polymer includes an additive selected from the group consisting of drugs, radiopaque agents and magnetic heating agents.

34. A method of delivering a stent into a lumen using a catheter, the method comprising:

delivering an apertured stent formed of a polymer and mounted on an expandable member of a catheter into a lumen,

expanding the expandable member to also expand the stent within the lumen so that the polymer does not substantially flow and substantial stress relaxation or creep does not occur so that the geometry of the tubular member is maintained; and

unexpanding the expandable member.

35. The method of claim 34, wherein the expandable member is a balloon at the distal tip of a catheter.

36. The method of claim 34, wherein the polymer has a melt temperature from about 40°

C. to about 60°

C.

37. The method of claim 34, wherein the polymer has a glass transition temperature is from about 40°

C. to about 60°

C.

38. The method of claim 34, wherein the lumen is a vascular lumen.

39. The method of claim 34, wherein the lumen is a non-vascular lumen.

40. A method of delivering a tubular prosthesis formed of a polymer into a body lumen, comprising

delivering the tubular prosthesis into the lumen, and

expanding the endoprosthesis under conditions of expanding pressure and rising temperature, wherein during expansion the wall thickness of the prosthesis is substantially maintained.

41. A method of making an implantable medical device comprising:

forming a tube from a polymer, the tube having a first diameter and including a wall;

cutting an aperture pattern into the wall of the tube while the tube has the first diameter;

crosslinking the polymer while the tube has the first diameter; and

deforming the tube to a second diameter, the second diameter smaller than the first diameter.

42. A method of delivering an implantable medical device comprising:

providing a catheter having an expandable member at its distal end;

placing a device made by the method of claim 41 onto the expandable member;

delivering the device to a body lumen;

expanding the device under conditions of expanding pressure and temperature to cause expansion of the device to the larger diameter; and

cooling the stent so that the device remains in the expanded larger diameter in the body lumen; and

removing the catheter from the body, thereby leaving behind the device within the body.

43. A method of making an implantable medical device comprising:

forming a tube from a polymer, the tube having a first diameter and including a wall;

cutting an aperture pattern into the wall while the tube has the first diameter; and

crosslinking the polymer while the tube has the first diameter.

44. A method of delivering an implantable medical device comprising:

providing a catheter having an expandable member at its distal end;

placing a device made by the method of claim 43 onto the expandable member;

delivering the device to a body lumen;

expanding the device under conditions of expanding pressure and temperature to cause expansion of the device to the larger diameter; and

cooling the stent so that the device remains in the expanded larger diameter in the body lumen; and

removing the catheter from the body, thereby leaving behind the device within the body.

45. An implantable medical apparatus, comprising:

an element operable for movement within the body by mechanical force applied to the element, said element including a polymer having a melt or glass transition temperature in the range above body temperature to about 60°

C. and exhibiting a plateau in a plot of storage modulus as a function of temperature at melt or glass transition.

46. The apparatus of claim 45, wherein the element is a stent.

47. The apparatus of claim 46, wherein the stent is a generally tubular body including an apertured wall.

48. The apparatus of claim 47, wherein the stent is operable for expansion from a first, smaller diameter to a second larger diameter for implantation in a lumen, wherein the thickness of the stent wall varies by about 1% or less between the first and second diameter.

49. The apparatus of claim 47, wherein the stent can be bent around a mandrel of about 0.75 cm radius without kinking.

50. A medical device comprising a polymer having a melt or glass transition temperature above body temperature and exhibiting an approximate plateau in a plot of storage modulus as a function of temperature at melt or glass transition.

51. The medical device of claim 50, wherein the melt or glass transition temperature is above about 37°

C.

52. The medical device of claim 50, wherein the melt or glass transition temperature is above about 50°

C.

53. The medical device of claim 50, wherein the melt or glass transition temperature is between about 37°

C. and about 50°

C.

54. The medical device of claim 50, wherein the element undergoes a triggerable event at about the plateau.

55. The medical device of claim 54, wherein the triggerable event is a change in the flexibility.

56. The medical device of claim 54, wherein the triggerable event is a change in the porosity.

57. The medical device of claim 54, wherein the triggerable event is a change in the coefficient of friction.

58. The medical device of claim 54, wherein the triggerable event is a change in the surface roughness.

59. The medical device of claim 54, wherein the medical device is a stent and has a portion that has a collapsed position that can be reverted to an expanded position by a trigger subsequent to insertion into the body.

60. A polymeric stent having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen.

61. The stent of claim 60, wherein the stent is in the form of a coiled elongated element.

62. The stent of claim 61, wherein when the stent is heated to a second temperature higher than the first temperature, the modulus of the element lowers sufficiently that the stent can be removed from a cavity or lumen as a substantially uncoiled element.

63. The stent of claim 60, wherein the portion is at an end of the stent.

64. The stent of claim 63, wherein the portion of the stent is flared.

65. The stent of claim 60, wherein at least two portions of the stent have a collapsed position that can be reverted to an expanded position following insertion into a cavity or lumen.

66. The stent of claim 61, wherein the elongated element comprises a strand.

67. The stent of claim 61, wherein the elongated element comprises a tape.

68. The stent of claim 61, wherein the elongated element comprises a flattened tube.

69. The stent of claim 68, wherein the flattened tube has a generally central opening that includes a medicament that can be released by the inserted stent.

70. The stent of claim 60, wherein the first temperature is greater than about 37°

C.

71. The stent of claim 62, wherein the second temperature is greater than about 37°

C.

72. The stent of claim 60, wherein the stent comprises a polymer selected from a group consisting of polynorbornene and copolymers of polynorbornene, polyethylene, styrenic block copolymer elastomers, polymethylmethacrylate, polyurethane, polyisoprene, polycaprolactone and copolymers of polycaprolactone, polylactic acid (PLA) and copolymers of polylactic acid, polyglycolic acid and copolymers of polyglycolic acid, copolymers of PLA and PGA, polyenes, nylons, polycyclooctene, polyvinyl acetate, polyvinylidene fluoride polyvinylchloride (PVC) and blends thereof.

73. The stent of claim 60, wherein the stent has a length and the portion comprises less than 50% of the length of the stent.

74. A polymeric stent in the form of a coiled elongated element, and having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen, and wherein when the stent is heated to a second temperature higher than the first temperature, the modulus of the element lowers sufficiently that the stent can be removed from a cavity or lumen as a substantially uncoiled element.

75. A method of treating a non-vascular cavity or lumen in a mammal, the method comprising:

inserting, into the non-vascular lumen or cavity of the mammal, a polymeric stent having a portion in a collapsed position that can be reverted to an expanded position by heating following insertion; and

heating the inserted stent sufficiently to revert the portion in the collapsed position to the expanded position.

76. The method of claim 75, further comprising:

heating the stent having the portion in the expanded position sufficiently to soften the stent; and

removing the softened stent from the cavity or lumen.

77. The method of claim 75, wherein the portion is at an end of the stent.

78. The method of claim 77, wherein the portion of the stent is flared.

79. The method of claim 75, wherein at least two portions of the stent have a collapsed position that can be reverted to an expanded position following insertion, and wherein during the heating both portions revert to expanded positions.

80. The method of claim 75, wherein the stent is in the form of a coiled elongated element.

81. The method of claim 75, wherein the collapsed position that can be reverted to an expanded position following insertion is not an end of the stent.

82. The method of claim 80, further comprising:

heating the stent sufficiently to soften the stent; and

removing the softened stent from the cavity or lumen as a substantially uncoiled strand.

83. The method of claim 75, wherein the heating is performed with a liquid.

84. The method of claim 75, wherein the heating is performed so that the temperature is less than about 55°

C.

85. The method of claim 75, wherein the heating is performed by a delivery tube including a warmed liquid.

86. The method of claim 75, wherein the delivery tube is a balloon catheter.

87. The method of claim 75, wherein the heating is performed using RF energy.

88. The method of claim 75, wherein the heating is performed using IR energy.

89. The method of claim 75, wherein the heating is performed using inductive heating.

90. The method of claim 89, wherein the stent further comprises metal particles.

91. The method of claim 75, wherein the lumen is a urethra.

92. The method of claim 75, wherein the lumen is a biliary duct.

93. The method of claim 75, wherein the lumen is a cystic duct.

94. The method of claim 75, wherein the lumen is in the gastrointestinal system.

95. The method of claim 75, wherein the lumen is in the pulmonary system.

96. The method of claim 75, wherein the lumen is in the hepatic system.

97. The method of claim 75, wherein the stent comprises a polymer selected from the group consisting of polynorbomene and copolymers of polynorbomene, polyethylene, styrenic block copolymer elastomers, polymethylmethacrylate, polyurethane, polyisoprene, polycaprolactone and copolymers of polycaprolactone, polylactic acid (PLA) and copolymers of polylactic acid, polyglycolic acid and copolymers of polyglycolic acid, copolymers of PLA and PGA, polyenes, nylons, polycyclooctene, polyvinyl acetate, polyvinylidene fluoride polyvinylchloride (PVC) and blends thereof.

98. A polymeric stent comprising metal particles, wherein a portion of the stent has a collapsed position that can be reverted to an expanded position by heating after insertion of the stent.

99. The stent of claim 98, wherein the stent can be heated by inductive heating to revert the portion in the collapsed position to the expanded position.

100. A stent having an exterior surface that includes a plurality of protruding elements that extend outwardly from the surface, the stent also having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen.

101. The stent of claim 100, wherein the protruding elements are formed of monofilament.

102. The stent of claim 101, wherein the monofilament includes a plurality of constrictions along its length.

103. The stent of claim 100, wherein the protruding elements are integral with and formed from the exterior surface.

104. A method of treating a cavity or lumen in a mammal, the method comprising:

inserting, into the lumen or cavity of the mammal, a polymeric stent having an exterior surface that includes a plurality of protruding elements that extend outwardly from the surface, the stent also having a portion that has a collapsed position that can be reverted to an expanded position by heating above a first temperature subsequent to insertion of the stent into a cavity or lumen; and

heating the inserted stent sufficiently to revert the portion in the collapsed position to the expanded position.

105. The method of claim 104, further comprising:

heating the stent sufficiently to soften the stent; and

removing the softened stent from the cavity or lumen as a substantially uncoiled strand.

106. An implantable endoprosthesis, comprising:

a tubular member comprising a polymeric material, the tubular member including a wall and having a first transverse dimension and a first longitudinal length, measured when at the first transverse dimension, sized for delivery into a lumen and which, on exposure to an elevated temperature, can be expanded to a second transverse dimension that is at least about fifty percent larger than the first transverse dimension within the lumen, the first and second transverse dimensions being measured from an outer surface of the wall of the tubular member, the tubular member also having a second longitudinal length, measured when at the second transverse dimension, wherein after expansion from the first transverse dimension to the second transverse dimension, the second longitudinal length decreases by less than about fifty percent, measured relative to the first longitudinal length.

107. The implantable endoprosthesis of claim 106, wherein the tubular member has a wall thickness, measured from an inner surface of the wall to the outer surface of the wall, and wherein the wall thickness decreases by greater than about fifty percent after expansion from the first transverse dimension to the second transverse dimension.

108. The implantable endoprosthesis of claim 107, wherein the wall thickness decreases by greater than about seventy-five percent after expansion from the first transverse dimension to the second transverse dimension.

109. The implantable endoprosthesis of claim 106, wherein after expansion from the first transverse dimension to the second transverse dimension that is at least about seventy-five percent larger than the first transverse dimension, the second longitudinal length decreases by less than about thirty percent, measured relative to the first longitudinal length.

110. The implantable endoprosthesis of claim 106, wherein the tubular member is approximately circular in transverse cross-section.

111. The implantable endoprosthesis of claim 106, wherein the polymeric material has a softening temperature from about 40°

C. to about 60°

C.

112. The implantable endoprosthesis of claim 106, wherein the polymeric material is cross-linked.

113. The implantable endoprosthesis of claim 106, wherein the polymeric material is selected from the group consisting of polycyclooctene (PCO), styrenic elastomers, styrenic block copolymers, styrene-butadiene rubber, polyolefins, trans-isoprene, and blends thereof.

114. The implantable endoprosthesis of claim 106, wherein the polymeric material includes a radio-opaque agent.

115. The implantable endoprosthesis of claim 114, wherein the radio-opaque agent is selected from the group consisting of bismuth carbonate, barium sulfate, and mixtures thereof.

116. The implantable endoprosthesis of claim 106, wherein the polymeric material includes a thermal conductor.

117. The implantable endoprosthesis of claim 116, wherein the thermal conductor is a boron nitride.

118. The implantable endoprosthesis of claim 106, wherein the tubular member is substantially straight before it is expanded.

119. The implantable endoprosthesis of claim 106, wherein the tubular member is curved after it is expanded.

120. The implantable endoprosthesis of claim 106, wherein the outer surface of the wall of the tubular member includes a protruding element that extends outwardly from the outer surface after the tubular member is expanded.

121. The implantable endoprosthesis of claim 106, wherein the wall includes at least one aperture defined therein.

122. The implantable endoprosthesis of claim 106, wherein the plastic has a elastic modulus of greater than about 50,000 psi.

123. A method of treating a patient, comprising:

placing the tubular endoprosthesis of claim 106 on a delivery system;

inserting the endoprosthesis on the delivery system into a lumen selected from the group consisting of a pulmonary lumen, an esophageal lumen, a biliary lumen, an enteral lumen, a ureteral lumen, a bronchial lumen, a tracheal lumen, and a urethral lumen; and

expanding the tubular endoprosthesis within the lumen.

124. The method of claim 123, wherein the delivery system includes a balloon catheter.

125. The method of claim 124, wherein the ballon is a heated balloon.

126. A product comprising a balloon catheter having an expandable member and a stent mounted on the expandable member, the stent comprising a tubular member formed of a polymer, the stent having an initial diameter for delivery into a body lumen and which can be expanded to a second diameter in the lumen by expanding the expandable member, wherein during expansion the polymer does not substantially flow and substantial stress relaxation or creep does not occur so that the geometry of the tubular member is maintained.

127. The product of claim 126, wherein the polymer is selected from the group consisting of polynorbomene, polycaprolactone, polyenes, nylons, polycyclooctene (PCO), blends of PCO and styrene-butadiene rubber, polyvinyl acetate/polyvinylidinefluoride (PVAc/PVDF), blends of PVAc/PVDF/polymethylmethacrylate (PMMA), polyurethanes, styrene-butadiene copolymers, polyethylene, trans-isoprene, blends of polycaprolactone and n-butylacrylate, POSS polyurethane polymers, PVC, plasticized PVC, and blends thereof.