Method for reducing stent weld profiles and a stent having reduced weldprofiles and a closed-end wire configuration

• US 20050256563A1
• Filed: 05/14/2004
• Published: 11/17/2005
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Leanna, Gary J., Norton, Paul K., Clerc, Claude O., Roberts, George Tom, Zupkofska, Michael
• Granted Patent: US 7,993,387 B2
• Time in Patent Office: Days
• US Class Current: 623/1.160
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2220/0058 soldered or brazed or welded
• CPC Class Codes: A61F 2230/001 Figure-8-shaped, e.g. hourglass-shaped
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: B23H 9/02 Trimming or deburring B23H9/003 takes precedence
• CPC Class Codes: B23K 11/008 Manufacturing of metallic grids or mats by spot welding
• CPC Class Codes: B23K 15/008 Spot welding
• CPC Class Codes: B23K 2101/06 Tubes
• CPC Class Codes: B23K 2101/22 Nets, wire fabrics or the like
• CPC Class Codes: B23K 2101/32 Wires
• CPC Class Codes: B23K 26/12 in a special atmosphere, e.g. in an enclosure
• CPC Class Codes: B23K 26/123 in an atmosphere of particular gases
• CPC Class Codes: B23K 26/211 with interposition of special material to facilitate connection of the parts
• CPC Class Codes: B23K 37/08 for flash removal
• CPC Class Codes: B23K 9/0026 specially adapted for particular articles or work
• CPC Class Codes: C23F 3/04 Heavy metals
• CPC Class Codes: C25F 3/16 Polishing
• CPC Class Codes: D04C 1/06 Braid or lace serving particular purposes
• CPC Class Codes: D04C 3/48 Auxiliary devices
• CPC Class Codes: D10B 2403/0112 : One smooth surface, e.g. laminated or coated
• CPC Class Codes: D10B 2509/06 : Vascular grafts; stents

Abstract

A method for making an implantable stent includes the steps of (i) providing a plurality of elongate stent wires; (ii) forming said wires into a hollow tubular structure having opposed first and second open ends; (iii) terminating said wires at the second end; (iv) aligning the wires at the second end into a plurality of mated adjacent wires to define a plurality of abutting regions; (v) welding the mated adjacent wires to one and the other at the abutting regions to define a plurality of welds; and optionally (vi) chemically or electro-chemically removing a portion of the welds. The method may further include the steps of (a) extending at least one of the mated stent wires to provide an extended stent wire; (b) looping the extended stent wire so the extended end abuts a proximal pair of stent wires; and (c) welding the extended and looped wire to the proximal pair of wires. The step of looping may include the forming of the wire into a equilaterally arched loop having an apex, but not having other sharp bends.

Claims

1. A method for making an implantable stent comprising:

providing a plurality of elongate stent wires;

forming said wires into a hollow tubular structure having opposed first and second open ends;

terminating said wires at said second end;

aligning said wires at said second end into a plurality of mated adjacent wires to define a plurality of abutting regions; and

welding said mated adjacent wires to one and the other at said abutting regions to define a plurality of welds.

2. The method of claim 1, further comprising:

chemically or electro-chemically removing a portion of said welds.

3. The method of claim 2, further comprising:

chemically or electro-chemically removing a portion of said mated adjacent wires, wherein said portion is proximal to said welds.

4. The method of claim 2, wherein said step of chemically or electro-chemically removing includes chemical or electro-chemical polishing.

5. The method of claim 3, wherein said step of chemically or electro-chemically removing includes chemical or electro-chemical polishing.

6. The method of claim 1, wherein said mated adjacent wires are substantially parallel to one and the other at said abutting regions.

7. The method of claim 1, wherein the step of welding comprises the step of providing an inert gas proximal to the weld areas.

8. The method of claim 1, wherein the step of welding includes welding selected from the group consisting of laser welding, electron beam welding resistance welding, tungsten inert gas welding, metal inert gas welding and combinations thereof.

9. The method of claim 1, wherein the step of forming said tubular structure comprises braiding said wires, winding said wires, knitting said wires, and combinations thereof.

10. The method of claim 1, wherein said wires comprise a wire material and further wherein said welding step further comprises providing a filling material, wherein said wire material and said filling material are the same type of material.

11. The method of claim 1, wherein said wires have a diameter and further wherein said welds have a thickness less the diameter of one of the mated adjacent wires

12. The method of claim 1, wherein said wire comprises a radiopaque material.

13. The method of claim 2, wherein the step of chemically or electro-chemically removing said portion of said welds includes chemical polishing or etching, electro-chemical polishing or etching, jet-electrochemical polishing and combinations thereof.

14. The method of claim 13, wherein the step of electrochemical polishing or jet-electrochemical polishing further includes the step of providing an electrolyte, wherein the electrolyte is selected from the group consisting of NaClO₃ electrolyte, NaNO₃ electrolyte, NaCl electrolyte, Na₂Cr₂O₇ electrolyte, HOCH₂CH₂OH electrolyte, and combinations thereof.

15. The method of claim 13, wherein the step of chemical polishing or chemical etching further includes the step of providing an oxidizing acid.

16. The method of claim 2, wherein the step of electro-chemically removing said portion of said welds further includes the step of

providing an electrolyte;

placing a cathode into said electrolyte;

placing a portion of said stent having said welds into said electrolyte; and

providing an electrical voltage or current so that a portion of said welds dissolves into the electrolyte.

17. The method of claim 1, further comprising the steps of:

extending at least one of the mated stent wires to provide an extended stent wire;

looping said extended stent wire so the extended end abuts a proximal pair of stent wires; and

welding the extended and looped wire to said proximal pair of wires.

18. The method of claim 17, wherein the step of looping includes forming the wire into an equilaterally arched loop having an apex, but not having other sharp bends.

19. The method of claim 17, the step of looping includes forming the wire into an equilaterally arched loop having one vertex having similar curvatures on either side of said one vertex, wherein said equilaterally arched loop does not contain a second vertex having dissimilar curvatures on either side of the second vertex.

20. The method of claim 1, further comprising the steps of:

extending at least one of the mated stent wires past the abutting regions to provide an extended stent wire; and

looping said extended stent wire at its extended end to form a coil thereat.

21. The method of claim 20, wherein a plurality of extended wires are formed into one coil.

22. The method of claim 1, wherein the elongate wires comprise biocompatible materials selected from the group consisting of nitinol, cobalt-based alloy, stainless steel, platinum, gold, titanium, tantalum, niobium, and combinations thereof.

23. The method of claim 22, wherein the elongate wires comprise nitinol.

24. The method of claim 1, wherein the elongate wires are composite wires for improved radiopacity.

25. The method of claim 24, wherein the elongate wires have an inner core of tantalum, gold, platinum, iridium or combination of thereof and an outer portion of nitinol.

26. An implantable stent comprising:

a plurality of wires arranged to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends, wherein the wires terminate at said second open end ends and adjacently abutting wires are welded at said second open end with a welding material to provide welds, and further wherein at least a portion of the welded material has been removed to reduce the profile of the welds.

27. The stent of claim 26, wherein said welding material formed from said adjacently abutting wires.

28. The stent of claim 26, wherein said welding material is a filling material.

29. The stent of claim 26, where the portion of welded material has been removed by chemical or electrochemical polishing.

30. The stent of claim 26, wherein a portion of the adjacently abutting wires proximal to said welds has been removed by chemical or electrochemical polishing.

31. The stent of claim 29, wherein a portion of the adjacently abutting wires proximal to said welds has been removed by chemical or electrochemical polishing.

32. The stent of claim 31, where at least about 25% to about 50% by weight of the stent and weld material at the weld location has been removed.

33. The stent of claim 26, wherein the reduced profile of the welds are from about 5 to about 50 linear percent of a diameter of the stent wires.

34. The stent of claim 26, wherein the wires comprise a biocompatible material selected from the group consisting of nitinol, stainless steel, cobalt-based alloy, platinum, gold, titanium, tantalum, niobium, and combinations thereof.

35. The stent of claim 34, wherein the weld material and the wire material are the same.

36. The stent of claim 34, wherein the weld material and the wire material are nitinol.

37. The stent of claim 34, wherein the elongate wires have an inner core of tantalum gold, platinum, iridium or combination of thereof and an outer portion of nitinol.

38. The stent of claim 26, wherein at least one some of the adjacently abutting stent wires are extended past the welds and looped into an equilaterally arched loop having an apex, but not having other sharp bends.

39. The stent of claim 26, wherein at least some of the adjacently abutting stent wires are extended past the welds and looped into an equilaterally arched loop having one vertex having similar curvatures on either side of said one vertex, wherein said equilaterally arched loop does not contain a second vertex having dissimilar curvatures on either side of the second vertex.

40. The stent of claim 26, wherein at least some of the adjacently abutting stent wires are extended past the welds and looped to form a coil thereat.

41. The stent of claim 26, wherein at least some of the adjacently abutting stent wires are extended past the welds and looped to form one coil thereat.

42. The stent of claim 26, wherein the stent is coated with silicone.

43. The stent of claim 26, wherein the stent is partially or fully covered with silicone.

44. The stent of claim 26, further comprising a hollow tubular graft disposed over the interior or the exterior surface.

47. The stent of claim 26, wherein the stent is a braided stent.

48. The stent of claim 26, further including a polymeric ring disposed over the exterior surface at said second open end.

49. The stent of claim 26, further including a metal or suture loop secured to one of said open ends.

45. The stent of claim 45, wherein the graft is a polymeric material.

46. The stent of claim 46, wherein the polymeric material is selected from the group consisting of polyester, polypropylene, polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, and combinations thereof.

50. A method for making an implantable stent comprising:

providing a plurality of elongate stent wires;

forming said wires into a hollow tubular structure having opposed first and second open ends;

terminating said wires at said second end;

aligning said wires at said second end into a plurality of mated adjacent wires to define a plurality of abutting regions;

welding said mated adjacent wires to one and the other at said abutting regions to define a plurality of welds; and

chemically or electro-chemically removing a portion of said welds and chemically or electro-chemically removing a portion of said mated adjacent wires, wherein said portion of said mated adjacent wires is proximal to said welds.

51. A method for making an implantable stent comprising:

providing a plurality of elongate stent wires;

forming said wires into a hollow tubular structure having opposed first and second open ends;

terminating said wires at said second end;

aligning said wires at said second end into a plurality of mated adjacent wires to define a plurality of abutting regions; and

extending at least one of the mated stent wires to provide an extended stent wire;

looping said extended stent wire so the extended end abuts a proximal pair of stent wires, wherein the step of looping includes forming the wire into an equilaterally arched loop having an apex, but not having other sharp bends; and

welding said mated adjacent wires to one and the other at said abutting regions and

welding extended and looped wire to said proximal pair of wires.

52. An implantable stent comprising:

a plurality of wires arranged to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends, wherein the wires terminate at said second open end ends and adjacently abutting wires are welded at said second open end with a welding material to provide welds, and further wherein at least one some of the adjacently abutting stent wires are extended past the welds and looped into an equilaterally arched loop having an apex, but not having other sharp bends.