Devices configured from strain hardened Ni Ti tubing

• US 6,551,341 B2
• Filed: 06/14/2001
• Issued: 04/22/2003
• Est. Priority Date: 06/14/2001
• Status: Expired due to Term

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Advanced Cardiovascular Systems Incorporated
• Inventors: Papp, John E., Patel, Anuja H., Boyle, William J., Boylan, John F.
• Primary Examiner(s): Izaguirre, Ismael
• Application Number:
  US09/882,930
• Publication Number:
  US 20020193824A1
• Time in Patent Office: 677 Days
• Field of Search: 606/200, 606/108, 606/194, 420/446, 420/441, 420/451
• US Class Current: 606/200
• CPC Class Codes: A61F 2002/018 made from tubes or sheets of material, e.g. by etching or laser-cutting
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2230/0067 conical
• CPC Class Codes: A61L 31/022 Metals or alloys

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 is disclosed. 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 is disclosed. Linear pseudoelastic nitinol is used in the medical device as distinct from non-linear pseudoelastic (i.e., superelastic) nitinol. The expandable strut assembly is made from a small diameter tubing of cold worked nickel-titanium alloys. The self-expanding struts that deploy the filter element is laser cut from a large diameter cold worked nickel-titanium alloy, then joined to the small diameter tubing.

Claims

1. A medical device for use in a body lumen, comprising:

a tubular body formed from small diameter tubing;

a plurality of struts formed from a large diameter tubing and disposed on the tubular body such that the struts project radially outward in an unconstrained state;

wherein the large diameter tubing includes a cold formed nickel-titanium alloy, and the nickel-titanium alloy is in a martensitic phase only regardless of stress applied to the alloy, and wherein the tubular body has been heat treated and a hysteresis curve of the nickel-titanium alloy does not include a stress plateau; and

a sheath at least partially enveloping the body and restraining the struts in a compressed state for delivery and retrieval of the device to and from the body lumen.

2. The medical device of claim 1, wherein the strut includes a long beam extending from a wide base, and the tubular body includes apertures formed therein, and wherein each aperture receives the wide base of the strut therein.

3. The medical device of claim 2, wherein the long beam of the strut includes a sloped profile.

4. The medical device of claim 2, wherein the aperture has a beveled interior edge and the wide base has a matching beveled edge.

5. The medical device of claim 2, wherein the medical device includes a sleeve that slidably engages the tubular body and covers the wide bases of the struts thereby retaining the struts to the body.

6. The medical device of claim 1, wherein the struts assume a shape imparted by cold forming.

7. The medical device of claim 6, wherein the cold forming occurs below the recrystallization temperature of the nickel-titanium alloy.

8. The medical device of claim 1, wherein the ingot transformation temperature of the nickel-titanium alloy is set above 37 degrees C.

9. The medical device of claim 1, wherein the small diameter tubing includes a nickel-titanium alloy.

10. A medical device for delivery to, deployment within, and removal from a lumen of a mammalian body, comprising:

a tubular body derived from small diameter tubing having a plurality of apertures formed therein;

a plurality of struts derived from a large diameter tubing;

wherein the apertures receive the struts therein and in an unstressed state bend away from the tubular body;

wherein the small and large diameter tubing include a cold formed nickel-titanium alloy, and the nickel-titanium alloy is in a martensitic phase only regardless of stress applied to the alloy; and

a sheath at least partially enveloping the body and restraining the struts in a compressed state for delivery and retrieval of the device to and from the lumen.

11. The medical device of claim 10, wherein the strut is cold formed to provide a curvature in a profile thereof.

12. The medical device of claim 10, wherein the strut includes a long beam extending from a wide base, and the wide base includes a radius of curvature matching a radius of curvature of the tubular body.

13. The medical device of claim 12, wherein some of the apertures have a first shape and the wide bases of the struts have a second shape complementary to the first shape so that at least a portion of the struts is recessed into the tubular body when attached thereto.

14. The medical device of claim 10, wherein the strut includes a long beam extending from a wide base, and the wide base includes a beveled periphery that wedges against a beveled periphery of the aperture.

15. The medical device of claim 10, wherein the strut has been heat treated and a hysteresis curve of the nickel-titanium alloy does not include a stress plateau.

16. The medical device of claim 10, wherein the nickel-titanium alloy has received low temperature heat treating and does not undergo a phase transformation when stressed.

17. The medical device of claim 10, wherein the struts are bonded to the tubular body.

18. A method for providing a medical device for use in a body lumen, comprising:

providing a small diameter tubing;

forming the small diameter tubing into a tubular body;

providing a large diameter tubing wherein the large diameter tubing includes a cold formed nickel-titanium alloy wherein the nickel-titanium alloy is in a martensitic phase only regardless of stress applied to the alloy;

heat treating the nickel-titanium alloy at a low temperature;

fashioning a plurality of struts from the large diameter tubing;

disposing the struts on the tubular body such that the struts project radially outward in an unconstrained state; and

providing a sheath that at least partially envelopes the body and restrains the struts in a compressed state for delivery and retrieval of the device to and from the body lumen.

19. The method for providing a medical device of claim 18, wherein the method further comprises providing a small tubing including a cold formed nickel-titanium alloy wherein the nickel-titanium alloy is in a martensitic phase only regardless of stress applied to the alloy.

20. The method for providing a medical device of claim 18, wherein the strut is cold formed to achieve a curved profile.

21. A medical device for use in a body lumen, comprising:

a tubular body formed from small diameter tubing;

a plurality of struts formed from a large diameter tubing and disposed on the tubular body such that the struts project radially outward in an unconstrained state;

wherein the large diameter tubing includes a cold formed nickel-titanium alloy that includes heat treating and wherein a hysteresis curve of the nickel-titanium alloy does not include a stress plateau, and the nickel-titanium alloy is in a martensitic phase only regardless of stress applied to the alloy; and

a sheath at least partially enveloping the body and restraining the struts in a compressed state for delivery and retrieval of the device to and from the body lumen.