Polymeric stent polishing method and apparatus

• US 8,580,180 B2
• Filed: 12/21/2009
• Issued: 11/12/2013
• Est. Priority Date: 07/29/2005
• Status: Active Grant

• Current Assignee: Advanced Cardiovascular Systems Incorporated
• Original Assignee: Advanced Cardiovascular Systems Incorporated
• Inventors: Wu, Patrick P.
• Primary Examiner(s): Johnson, Christina
• Assistant Examiner(s): HUDA, SAEED M
• Application Number:
  US12/643,679
• Publication Number:
  US 20100109204A1
• Time in Patent Office: 1,422 Days
• Field of Search: 264/345, 264/162, 264/491, 264/405, 264/476, 264/492, 623/1.1
• US Class Current: 264/345
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• 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: B29C 59/00 Surface shaping of articles, e.g. embossing; Apparatus therefor in-mould printing B29C37/0025; by using liquids B29C71/0009; by using gases without chemical reaction B29C71/009; for decorating in general B44; abrasive blasting B24C; chemical aspects C08J7/00
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29C 71/04 by wave energy or particle radiation , e.g. for curing or vulcanising preformed articles during moulding, e.g. in a mould B29C35/08
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses

Abstract

A method and apparatus for simultaneously polishing the inner and outer surfaces of an unpolished polymeric stent using a heat process. The unpolished stent can be mounted, for example, on a “spiral-mandrel,” a tubular helical structure with gaps in between a series of coils of the structure. Heat from a heat source can then applied to the spiral-mandrel at a range between the glass transition temperature and melting temperature of the polymer of the stent.

Claims

1. A method of polishing a polymeric stent, comprising:

mounting an unpolished polymeric stent on a spiral mandrel,

wherein an outer diameter of the spiral mandrel is such that an abluminal surface of the spiral mandrel matches the luminal surface of the polymeric stent; and

subsequent to mounting the unpolished polymeric stent on the spiral mandrel, directing heat into an interior space of the unpolished polymeric stent and against a luminal surface of the stent to thereby polish the luminal surface, wherein the temperature of a polymer of the stent is increased to equal to or greater than a glass transition temperature and less than a melting temperature of the polymer.

2. The method of claim 1, wherein the heat is radiation heat.

3. The method of claim 1, wherein the heat is convection heat.

4. The method of claim 1, wherein the heat is hot gas.

5. The method of claim 1, wherein the directing includes directing the heat from the exterior of the stent through at least one interstitial gap in the wall of the stent and thereby to the interior space.

6. The method of claim 1, wherein the directing includes directing the heat axially into the interior space of the stent.

7. The method of claim 1, further comprising forming the spiral mandrel by wrapping a wire in a coiled manner around a mandrel and then separating the mandrel and the coiled wire.

8. The method of claim 1, wherein the heat is from a heater coil, radio frequency heater or gas blower.

9. The method of claim 1, wherein the heat is from an element capable of being inserted into a hollow longitudinal bore of the stent.

10. The method of claim 1, wherein the directing includes the luminal surface being subjected to the heat for three to eight seconds at a selected temperature of about 40°

C. to about 175°

C.

11. The method of claim 1, wherein the heat polishes an abluminal surface of the stent.

12. The method of claim 1, wherein the directing is at a heating station, and further comprises conveying the unpolished stent by the station.

13. The method of claim 12, wherein the conveying includes the stent being stopped during the directing at the heating station.

14. The method of claim 1, wherein the heat is from a heater which radially encircles the stent.

15. The method of claim 1, wherein the directing includes radially directing heat from multiple spaced sources encircling the stent.

16. The method of claim 1, additionally including rotating the stent during the directing of heat.

17. The method of claim 16, additionally including rotating the stent during the polishing process, wherein the directing of heat is terminated before the rotation of the stent and wherein the rotation of the stent is terminated prior to the directing of the heat.

28. The method of claim 1, wherein the directing includes directing the heat between adjacent spaced coils of the spiral mandrel.

18. A method of polishing a polymeric stent, comprising:

mounting a stent made from a material including a polymer onto a structure having a series of gaps comprising openings between an abluminal and luminal surface of the structure; and

after the mounting, subjecting the stent to heat from a heat source so as to modify a surface morphometry of at least a section of the stent from an angular configuration to a non-angular configuration, wherein the heat passes through the gaps between the abluminal and the luminal surface of the structure to reach a luminal surface of the stent, wherein the temperature of the polymer of the stent is increased to less than a melting temperature of the polymer.

19. The method of claim 18, wherein the structure includes a tubular coiled wire, a tubular braided structure, a porous sheath, a porous hypotube or a series of interconnecting cylindrical rings.

20. The method of claim 18, wherein the structure is made from a material including a heat conductive material.

21. The method of claim 18, wherein the structure comprises a metallic material.

22. The method of claim 18, wherein the structure is made from a non-heat conductive material.

23. The method of claim 18, wherein the heat is at a temperature equal to or greater than a glass transition temperature of a polymer of the stent.

24. The method of claim 18, wherein the heat is at a temperature equal to or greater than a melting temperature of a polymer of the stent.

25. The method of claim 18, wherein the heat source is positioned external to the structure.

26. The method of claim 18, wherein the heat source encircles the stent.

27. A method of polishing a polymeric stent comprising:

directing heat into an interior space of an unpolished polymeric stent and against a luminal surface of the stent to thereby polish the luminal surface;

wherein the duration of the heating is between two and ten seconds followed by termination of the heat,

wherein the temperature of a polymer of the stent is increased to equal to or greater than a glass transition temperature and less than a melting temperature of the polymer.

29. The method of claim 27, wherein the polymer is poly(L-lactide) and the temperature of the heat is from about 40°

C. to about 175°

C.

30. The method of claim 29, wherein the temperature of the heat is from about 55°

C. to about 65°

C.