Method of forming a tubular membrane on a structural frame

• US 20030209835A1
• Filed: 03/28/2003
• Published: 11/13/2003
• Est. Priority Date: 05/10/2002
• Status: Active Grant

• Current Assignee: Cardinal Health Switzerland 515 GmbH (Cardinal Health, Inc.)
• Original Assignee: Cordis Corporation (Cardinal Health, Inc.)
• Inventors: Majercak, David Christopher, Chun, Iksoo, Roller, Mark B.
• Granted Patent: US 7,270,675 B2
• Time in Patent Office: Days
• US Class Current: 264/339
• CPC Class Codes: A61F 2/2412 with soft flexible valve members, e.g. tissue valves shaped like natural valves check valves with flexible valve members in general F16K15/14
• CPC Class Codes: A61F 2/2415 Manufacturing methods
• CPC Class Codes: A61F 2/2418 Scaffolds therefor, e.g. support stents
• CPC Class Codes: A61F 2/2475 Venous valves
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/825 having longitudinal struts
• 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 2002/91575 connected peak to trough
• CPC Class Codes: A61F 2002/91583 by a bridge, whereby at least one of its ends is connected along the length of a strut between two consecutive apices within a band
• CPC Class Codes: A61F 2220/0058 soldered or brazed or welded
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61L 2300/00 Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
• CPC Class Codes: A61L 27/18 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/34 Macromolecular materials
• CPC Class Codes: A61L 27/54 Biologically active materials, e.g. therapeutic substances A61L27/227 takes precedence
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: D01D 5/0084 Coating by electro-spinning, i.e. the electro-spun fibres are not removed from the collecting device but remain integral with it, e.g. coating of prostheses
• CPC Class Codes: D01F 6/32 comprising halogenated hydrocarbons as the major constituent
• CPC Class Codes: D01F 6/84 from copolyesters
• CPC Class Codes: D04H 3/07 : otherwise than in a plane, e.g. in a tubular way

Abstract

The present invention relates to a medical device and method of forming the medical device. In particular, the present invention relates to a medical device having a tubular membrane structure over a radially expandable structural frame, and to a method of forming the tubular membrane on the radially expandable structural frame. In one aspect, a structural frame is placed over a spinning mandrel and a fiber is electro-statically spun over at least a portion of the structural frame forming a membrane. A transfer sheath may be used between the mandrel and structural frame to prevent the electro-statically spun fiber from adhering to the mandrel. In another aspect, a first membrane is spun over the mandrel before the structural frame is placed over the mandrel. In this aspect, at least a portion of the structural frame is sandwiched between the membranes. The membrane or membranes and structural frame form a fiber spun frame assembly. The fiber spun frame assembly may be coated with an elastic polymer. In addition, the membrane or membranes may go through some post processing to achieve desired characteristics or configurations.

Claims

1. A method of forming a tubular membrane on a radially expandable structural frame, the method comprising the steps of:

placing a transfer sheath over a spinning mandrel;

placing the radially expandable structural frame over the transfer sheath;

electro-statically spinning a fiber directly onto at least a portion of the structural frame to form a tubular membrane, the structural frame and tubular membrane forming a fiber spun frame assembly; and

removing the fiber spun frame assembly from the spinning mandrel.

2. The method of claim 1 wherein the step of electro-statically spinning a fiber directly onto the structural frame comprises the steps of:

creating an electrical potential between a fiber forming liquid and a downstream component, whereby the fiber forming liquid is caused to produce a charged fiber;

hardening the fiber; and

collecting the hardened fiber on the structural frame.

3. The method of claim 2 wherein the step of creating the electrical potential comprises electrically charging the fiber forming liquid and grounding the downstream component.

4. The method of claim 3 wherein the step of electrically charging the fiber forming liquid comprises introducing the fiber forming liquid into an electric field.

5. The method of claim 3 wherein the step of electrically charging the fiber forming liquid comprises electrically charging an introducer device, thus causing the fiber forming liquid to assume the same charge as the introducer device.

6. The method of claim 5 wherein the introducer device is a spray nozzle.

7. The method of claim 5 wherein the introducer device is an injection orifice.

8. The method of claim 5 wherein the introducer device is an extruder.

9. The method of claim 2 wherein the fiber forming liquid is a polymer.

10. The method of claim 9 wherein the polymer is a fluoropolymer.

11. The method of claim 10 wherein the fluropolymer is vinylidene fluoride/hexofluoropropylene having a weight to weight ratio of between 75%/25% and 100%/0%.

12. The method of claim 9 wherein the polymer is a bioabsorbable polymer.

13. The method of claim 12 wherein the bioabsorbable polymer is a polylactic acid/polycaprolactone having a weight to weight ratio of between 50%/50% and 70%/30%.

14. The method of claim 12 wherein the bioabsorbable polymer is a polyglycolic acid/polycaprolactone having a weight to weight ratio of between 50%/50% and 70%/30%.

15. The method of claim 9 wherein the polymer comprises a bioabsorbable polymer from the group consisting of homopolymers and copolymers.

16. The method of claim 9 wherein the polymer comprises a polymer from the group consisting of nonabsorbable siliconized polyurethane, non-siliconized polyurethane, siliconized polyureaurethane and natural polymers.

17. The method of claim 2 wherein the fiber forming liquid comprises a therapeutic agent.

18. The method of claim 2 wherein the fiber forming liquid comprises a pharmaceutic agent.

19. The method of claim 2 wherein the step of hardening the fiber comprises cooling the fiber forming liquid until the fiber forming liquid will not lose its fibrous shape.

20. The method of claim 2 wherein the step of hardening the fiber comprises directing an air stream over the fiber forming liquid.

21. The method of claim 2 wherein the step of hardening the fiber comprises introducing a chemical hardener into the fiber forming liquid.

22. The method of claim 2 wherein the step of hardening the fiber comprises:

placing a polymer into solution with a solvent to form the fiber forming liquid; and

evaporating the solvent from the fiber forming liquid.

23. The method of claim 2 wherein the step of collecting the hardened fiber on the structural frame comprises:

electrically attracting the fiber forming liquid to a downstream component; and

rotating the structural frame about its longitudinal axis by spinning the spinning mandrel.

24. The method of claim 1 wherein the tubular membrane has a wall thickness in the range from about 5 μ

m to about 100 μ

m.

25. The method of claim 1 further comprising coating the fiber spun frame assembly with a polymer solution.

26. The method of claim 25 wherein the step of coating comprises spraying the polymer over the fiber spun frame assembly.

27. The method of claim 25 wherein the step of coating comprises dipping the fiber spun frame assembly in the solution of polymer.

28. The method of claim 25 wherein the step of coating comprises:

dipping the fiber spun frame assembly in the solution of polymer; and

spinning the dip coated fiber spun frame assembly to evenly distribute the coating.

29. The method of claim 25 wherein the polymer solution is a fluoropolymer.

30. The method of claim 29 wherein the fluoropolymer is a vinylidene fluoride/hexofluoropropylene having a weight to weight radio of between 50%/50% to 70%/30%.

31. The method of claim 25 wherein the polymer solution is siliconized polyurethane.

32. The method of claim 25 wherein the polymer solution is non-siliconized polyurethane.

33. The method of claim 25 wherein the polymer solution comprises a therapeutic agent.

34. The method of claim 25 wherein the polymer solution comprises a pharmaceutic agent.

35. The method of claim 1 further comprising performing post processing of the tubular membrane.

36. The method of claim 35 wherein the step of post processing includes reshaping the tubular membrane.

37. The method of claim 35 wherein the step of post processing includes thinning at least a portion of the tubular membrane.

38. The method of claim 35 wherein the step of post processing includes thickening at least a portion of the tubular membrane.

39. The method of claim 35 wherein the step of post processing includes forming cusps in the tubular membrane.

40. A method of forming a tubular membrane on a radially expandable structural frame, the method comprising the steps of:

placing the radially expandable structural frame over a spinning mandrel;

electro-statically spinning a first fiber directly onto at least a portion of the structural frame to form a tubular membrane, the structural frame and tubular membrane forming a fiber spun frame assembly; and

removing the fiber spun frame assembly from the spinning mandrel.

41. A method of forming a tubular membrane on a radially expandable structural frame, the method comprising the steps of:

placing a transfer sheath over a spinning mandrel;

electro-statically spinning a first fiber directly onto at least a portion of the transfer sheath to form a first tubular membrane;

placing the radially expandable structural frame over the first tubular membrane;

electro-statically spinning a second fiber directly onto at least a portion of the structural frame to form a second tubular membrane, the combination of the first tubular membrane, structural frame and second tubular membrane forming a fiber spun frame assembly; and

removing the fiber spun frame assembly from the spinning mandrel.

42. The method of claim 41 further comprising coating the fiber spun frame assembly with a polymer solution.

43. The method of claim 41 further comprising performing post processing of the tubular membrane.

44. A medical device having a tubular membrane structure comprising:

a radially expandable structural frame;

a polymer fiber membrane electrostatically spun over the structural frame; and

an outer membrane coated over the fiber membrane, the outer membrane and fiber membrane combining to form the tubular membrane structure.

45. The medical device of claim 44 wherein the polymer fiber membrane comprises a fluoropolymer.

46. The medical deice of claim 45 wherein the fluoropolymer is a vinylidene fluoride/hexofluoropropylene having a weight to weight ratio in the range from about 75%/25% to about 100%/0%.

47. The medical device of claim 44 wherein the polymer fiber membrane is a bioabsorbable polymer.

48. The medical device of claim 47 wherein the bioabsorbable polymer is a polylactic acid/polycaprolactone having a weight to weight ratio of between 50%/50% and 70%/30%.

49. The medical device of claim 47 wherein the bioabsorbable polymer is a polyglycolic acid/polycaprolactone having a weight to weight ratio of between 50%/50% and 70%/30%.

50. The medical device of claim 44 wherein the polymer fiber membrane comprises a bioabsorbable polymer from the group consisting of homopolymers and copolymers.

51. The medical device of claim 44 wherein the polymer fiber membrane comprises a polymer from the group consisting of nonabsorbable siliconized polyurethane, non-siliconized polyurethane, siliconized polyureaurethane and natural polymers.

52. The medical device of claim 44 wherein the polymer fiber membrane comprises a therapeutic agent.

53. The medical device of claim 44 wherein the polymer fiber membrane comprises a pharmaceutic agent.

54. The medical device of claim 44 wherein the polymer fiber membrane has a wall thickness in the range from about 5 μ

m to about 100 μ

m.

55. The medical device of claim 44 wherein the outer membrane comprises a polymer.

56. The medical device of claim 55 wherein the polymer is a fluoropolymer.

57. The medical deice of claim 56 wherein the fluoropolymer is a vinylidene fluoride/hexofluoropropylene having a weight to weight ratio in the range from about 50%/50% to about 70%/30%.

58. The medical device of claim 55 wherein the polymer is siliconized polyurethane.

59. The medical device of claim 55 wherein the polymer is non-siliconized polyurethane.

60. The medical device of claim 55 wherein the polymer comprises a therapeutic agent.

61. The medical device of claim 55 wherein the polymer comprises a pharmaceutic agent.

62. The medical device of claim 44 wherein the tubular membrane structure has a wall thickness in the range from about 5 μ

m to about 100 μ

m.

63. A medical device having a tubular membrane structure comprising:

an inner membrane formed from an electrostatically spun polymer fiber;

a radially expandable structural frame contracted over the inner membrane; and

an outer membrane formed from a polymer fiber membrane electrostatically spun over the structural frame, the inner membrane and outer membrane combining to form the tubular membrane structure.

64. The medical device of claim 63 wherein the outer membrane further comprises a polymer membrane coating.