Hollow Tubular Drug Eluting Medical Devices

• US 20110008405A1
• Filed: 07/09/2009
• Published: 01/13/2011
• Est. Priority Date: 07/09/2009
• Status: Active Grant

• Current Assignee: Medtronic Vascular, Inc. (Medtronic Plc)
• Original Assignee: Medtronic Vascular, Inc. (Medtronic Plc)
• Inventors: Birdsall, Matthew J., Storment, Christopher, Perkins, D.H., Thompson, Dustin
• Granted Patent: US 9,283,305 B2
• Time in Patent Office: Days
• US Class Current: 424/423
• CPC Class Codes: A61B 2017/00526 Methods of manufacturing
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61L 31/16 Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: A61M 25/0012 with embedded structures, e.g. coils, braids, meshes, strands or radiopaque coils
• CPC Class Codes: A61M 25/0015 Making lateral openings in a catheter tube, e.g. holes, slits, ports, piercings of guidewire ports; Methods for processing the holes, e.g. smoothing the edges
• CPC Class Codes: A61N 1/0587 Epicardial electrode systems; Endocardial electrodes piercing the pericardium

Abstract

A method of a forming a hollow, drug-eluting medical device includes providing composite member having an outer member and a core member disposed within a lumen of the outer member. The composite member is shaped into a pattern. Openings are formed through the outer member of the composite member. The composite member is processed to remove the core member from the lumen of the outer member without harming the outer member, leaving a hollow tubular member already formed into the desired pattern. The lumen of the outer member is filled with a therapeutic substance.

Claims

1. A method of forming a medical device comprising the steps of:

providing composite member including an outer member and a core member disposed within a lumen of the outer member;

shaping the composite member into a pattern;

forming openings through the outer member; and

after the step of shaping the composite member into the pattern, processing the composite member such that the core member is removed from the core member without adversely affecting the outer member.

2. The method of claim 1, further comprising the step of filling the lumen of the outer member with a therapeutic substance after the core member has been removed.

3. The method of claim 2, wherein the therapeutic substance is selected from the group consisting of antineoplastic, antimitotic, antiinflammatory, antiplatelet, anticoagulant, anti fibrin, antithrombin, antiproliferative, antibiotic, antioxidant, and antiallergic substances as well as combinations thereof.

4. The method of claim 2, wherein the medical device is a stent.

5. The method of claim 2, wherein the medical device is a surgical staple

7. The method of claim 2, wherein the medical device is a bone screw.

8. The method of claim 2, wherein the medical device is an electrode of an implantable cardioverter defibrillator.

9. The method of claim 1, wherein the step of processing the composite member comprises exposing the composite member to an etchant that reacts with the core member to remove the core member, wherein the etchant does not react with the outer member.

10. The method of claim 9, wherein the etchant is a liquid chemical that dissolves the core member.

11. The method of claim 10, wherein the outer member is formed from MP35N, the core member is formed from molybdenum, and the etchant is hydrogen peroxide.

12. The method of claim 10, wherein the outer member is formed from a nickel titanium alloy or stainless steel, the core member is formed from gold, and the etchant is potassium triiodide.

13. The method of claim 10, wherein the outer member is formed from an aluminum alloy or stainless steel, the core member is formed from copper, and the etchant is nitric acid.

14. The method of claim 9, wherein the etchant is a gas.

15. The method of claim 14, wherein the outer member is formed from MP35N, the core member is formed from one of tantalum, tungsten, molybdenum, niobium, rhenium, carbon, germanium, and silicon, and the etchant is xenon difluoride.

16. The method of claim 14, wherein the outer member is formed from MP35N, the core member is formed from one of tantalum, tungsten, molybdenum, niobium, rhenium, carbon, germanium, and silicon, and the etchant is bromine trifluoride.

17. The method of claim 14, wherein the outer member is formed from the group consisting of platinum, iridium, titanium, and tantalum, the core member is formed from nickel, and the etchant is carbon monoxide.

18. The method of claim 14, wherein the outer member is formed from stainless steel or nickel-based alloys, the core member is formed from titanium or zirconium, and the etchant is iodine.

19. The method of claim 9, wherein the core member is soluble in the etchant and the outer member is not soluble in the etchant.

20. The method of claim 19, wherein the outer member comprises platinum, the core member is selected from the group consisting of silver, gold, and copper, and the etchant comprises mercury.

21. The method of claim 19, wherein the outer member comprises tungsten, the core member comprises aluminum, and the etchant comprises liquid gallium.

22. The method of claim 1, wherein the step of processing the composite member comprises heating the composite member to a temperature to sublimate the core member.

23. The method of claim 22, wherein the outer member comprises molybdenum or tungsten, the core member comprises chromium, and the composite member is heated in a vacuum to a temperature above which chromium sublimates.

24. The method of claim 1, wherein the step of processing the composite member comprises heating the composite member to a temperature to melt the core member.

25. The method of claim 24, wherein the outer member is selected from the group consisting of MP35N, titanium, tantalum, and tungsten, the core member is selected from the group consisting of magnesium, aluminum, zinc, gold, and silver, and the composite member is heated to above a melting point temperature of the core member and below a melting point temperature of the outer member.

26. A method for forming a stent with hollow struts comprising the steps of:

providing a first tube made from a first material, the first tube having a wall defining an inner surface defining a first inner diameter and an outer surface defining a first outer diameter;

removing portions of the wall of the first tube such that the material remaining forms a first pattern;

after the removing step, placing a second tube made from a second material over the first tube, the second tube having a wall with an inner surface defining a second inner diameter that is larger than the first outer diameter;

after the removing step, placing a third tube made from the second material inside the first tube, the third tube having a wall with an outer surface defining a third outer diameter that is smaller than the first inner diameter;

pressing the first, second, and third tubes together such that the second and third tubes surround the remaining material of the first tube;

removing portions of the walls of the second tube and the third tube in a second pattern that captures the remaining material of the first tube and the material of the second and third tubes surrounding the remaining material of the first tube;

forming openings through at least one of the first tube and the second tube to access the remaining material of the first tube;

processing the remaining material such that the remaining material of the first tube is removed without damaging the remaining material of the second and third tubes, thereby leaving the remaining material of the second and third tubes as the hollow struts of the stent and an area where the remaining material of the first tube was removed as a cavity in the hollow struts.

27. The method of claim 26, further comprising the step of filling the cavity with a therapeutic substance.

28. The method of claim 27, wherein the therapeutic substance is selected from the group consisting of antineoplastic, antimitotic, antiinflammatory, antiplatelet, anticoagulant, anti fibrin, antithrombin, antiproliferative, antibiotic, antioxidant, and antiallergic substances as well as combinations thereof.

29. The method of claim 26, wherein the step of processing the remaining material comprises exposing the remaining material to an etchant that reacts with the first material to remove the first material, wherein the etchant does not react with the second material.

30. The method of claim 29, wherein the etchant is a liquid chemical that dissolves the first material.

31. The method of claim 30, wherein the second material is MP35N, the first material is molybdenum, and the etchant is hydrogen peroxide.

32. The method of claim 30, wherein the second material is a nickel titanium alloy or stainless steel, the first material is gold, and the etchant is potassium triiodide.

33. The method of claim 30, wherein the second material is an aluminum alloy or stainless steel, the first material is copper, and the etchant is nitric acid.

34. The method of claim 29, wherein the etchant is a gas.

35. The method of claim 34, wherein the second material is MP35N, the first material is selected from the group consisting of tantalum, tungsten, molybdenum, niobium, rhenium, carbon, germanium, and silicon, and the etchant is xenon difluoride.

36. The method of claim 34, wherein the second material is MP35N, the first material is selected from the group consisting of tantalum, tungsten, molybdenum, niobium, rhenium, carbon, germanium, and silicon, and the etchant is bromine trifluoride.

37. The method of claim 34, wherein the second material is selected from the group consisting of platinum, iridium, titanium, and tantalum, the first material is nickel, and the etchant is carbon monoxide.

38. The method of claim 34, wherein the second material is stainless steel or nickel-based alloys, the first material is titanium or zirconium, and the etchant is iodine.

39. The method of claim 29, wherein the first material is soluble in the etchant and the second material is not soluble in the etchant.

40. The method of claim 39, wherein the second material is platinum, the first material is selected from the group consisting of silver, gold, and copper, and the etchant comprises mercury.

41. The method of claim 39, wherein the second material is tungsten, the first material is aluminum, and the etchant comprises liquid gallium.

42. The method of claim 26, wherein the step of processing the remaining material comprises heating the remaining material to a temperature to sublimate the first material.

43. The method of claim 42, wherein the second material comprises molybdenum or tungsten, the first material comprises chromium, and the processing step comprises heating the remaining material in a vacuum to a temperature above which chromium sublimates.

44. The method of claim 26, wherein the step of processing the remaining material comprises heating the remaining material to a temperature to melt the first material.

45. The method of claim 44, wherein the second material is selected from the group consisting of MP35N, titanium, tantalum, and tungsten, the first material is selected from the group consisting of magnesium, aluminum, zinc, gold, and silver, and the processing step comprises heating the remaining material to above a melting point temperature of the first material and below a melting point temperature of the second material.