Heat treatment for cold worked nitinol to impart a shape setting capability without eventually developing stress-induced martensite

• US 7,976,648 B1
• Filed: 11/02/2000
• Issued: 07/12/2011
• Est. Priority Date: 11/02/2000
• Status: Expired due to Fees

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Boylan, John Francis, Lin, Zhi Cheng
• Primary Examiner(s): Manahan; Todd E
• Assistant Examiner(s): Lang; Amy
• Application Number:
  US09/705,422
• Time in Patent Office: 3,904 Days
• Field of Search: 604104-106, 604/93.1, 604/93.01, 623/1.14, 623/1.21, 623/1.29, 623/1.32, 623/1.44, 623/1.46, 623/1.11, 623/1.18, 623/1.15, 623/1.2, 623/1.12, 606169-171, 606/200, 606/194, 606/127, 606/159, 606/191, 606/198, 606/108, 606/114, 29 172- 179, 29/61, 294/47, 294/58, 295/57, 420/446, 420/441, 420/451, 148/676, 148/563, 723/701.3, 723/702.5, 723/702.7, 72274-276
• US Class Current: 148/563
• CPC Class Codes: A61F 2002/018 made from tubes or sheets of material, e.g. by etching or laser-cutting
• CPC Class Codes: A61F 2210/0023 operated at different temperatures whilst inside or touching the human body, heated or cooled by external energy source or cold supply
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2230/0067 conical
• CPC Class Codes: A61L 2400/16 Materials with shape-memory or superelastic properties
• CPC Class Codes: A61L 31/022 Metals or alloys
• CPC Class Codes: A61M 2025/09141 made of shape memory alloys which take a particular shape at a certain temperature
• CPC Class Codes: C22C 19/03 based on nickel
• CPC Class Codes: C22F 1/006 Resulting in heat recoverable alloys with a memory effect
• CPC Class Codes: C22F 1/10 of nickel or cobalt or alloys based thereon

Abstract

Cold worked nickel-titanium alloys that have linear pseudoelastic behavior without a phase transformation or onset of stress-induced martensite as applied to a medical device having a strut formed body deployed from a sheath. In one application, an embolic protection device that employs a linear pseudoelastic nitinol self-expanding strut assembly with a small profile delivery system for use with interventional procedures. The expandable strut assembly is covered with a filter element and both are compressed into a restraining sheath for delivery to a deployment site downstream and distal to an interventional procedure. Once at the desired site, the restraining sheath is retracted to deploy the embolic protection device, which captures flowing emboli generated during the interventional procedure. Linear pseudoelastic nitinol is used in the medical device as distinct from non-linear pseudoelastic (i.e., superelastic) nitinol.

Claims

1. A method of making an intralumen device, comprising:

receiving tubing made from a nickel-titanium alloy that is in a substantially fully martensitic state;

forming a plurality of struts in the received tubing to form a body;

cold working the body at least about 38 percent as measured by reduction in cross-sectional area, the nickel-titanium alloy remaining in the substantially fully martensitic state following the cold working;

heat treating the cold-work body under conditions so that the cold-work body remains in the substantially fully martensitic state; and

incorporating the heat-treated cold-worked body into the intralumen device.

2. The method of claim 1 wherein forming a plurality of struts in the received tubing to form a body comprises laser cutting the received tubing to form the plurality of struts.

3. The method of claim 1 wherein forming a plurality of struts in the received tubing to form a body comprises etching the received tubing to form the plurality of struts.

4. The method of claim 1 wherein the nickel-titanium comprises at least one additional alloying element selected from the group consisting of palladium, platinum, tungsten, and tantalum.

5. The method of claim 1 wherein incorporating the heat-treated cold-worked body into the intralumen device comprises incorporating the heat-treated cold-worked body into an embolic filter.

6. A method of making an intralumen device, comprising:

receiving tubing made from a nickel-titanium alloy that is in a substantially fully martensitic state;

forming a plurality of struts in the received tubing to form a body;

cold working the body at least about 38 percent as measured by reduction in cross-sectional area, the nickel-titanium alloy remaining in the substantially fully martensitic state following the cold working;

incorporating the cold-worked body into the intralumen device; and

wherein an accumulated heat treatment that the received tubing and the cold-worked body receives is up to 300°

C. for up to 5 minutes.

7. The method of claim 6 wherein forming a plurality of struts in the received tubing to form a body comprises laser cutting the received tubing to form the plurality of struts.

8. The method of claim 6 wherein forming a plurality of struts in the received tubing to form a body comprises etching the received tubing to form the plurality of struts.

9. The method of claim 6 wherein the nickel-titanium comprises at least one additional alloying element selected from the group consisting of palladium, platinum, tungsten, and tantalum.

10. The method of claim 6 wherein incorporating the cold-worked body into the intralumen device comprises incorporating the cold-worked body into an embolic filter.