Method of loading a medical device into a delivery system

• US 8,888,835 B2
• Filed: 04/23/2009
• Issued: 11/18/2014
• Est. Priority Date: 04/23/2008
• Status: Active Grant

• Current Assignee: Cook Medical Technologies, LLC (Cook Group Incorporated)
• Original Assignee: Cook Medical Technologies, LLC (Cook Group Incorporated)
• Inventors: Magnuson, Mark A., Carlson, James M.
• Primary Examiner(s): Erezo, Darwin
• Assistant Examiner(s): TON, MARTIN TRUYEN
• Application Number:
  US12/989,025
• Publication Number:
  US 20110137398A1
• Time in Patent Office: 2,035 Days
• Field of Search: 623/1.11
• US Class Current: 623/1.11
• CPC Class Codes: A61F 2/95 Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61F 2/9522 Means for mounting a stent or stent-graft onto or into a placement instrument
• CPC Class Codes: A61F 2/9524 Iris-type crimpers
• CPC Class Codes: A61F 2210/0014 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2250/0042 differing in shape-memory transition temperatures, e.g. in martensitic transition temperature, in austenitic transition temperature
• CPC Class Codes: C22F 1/00 Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working apparatus for mechanical working of metal B21, B23, B24
• 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
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A method of loading a medical device into a delivery system includes providing a two-stage shape memory alloy at a temperature at which at least a portion of the alloy includes austenite. A stress which is sufficient to form R-phase from at least a portion of the austenite is applied to the medical device at the temperature. A delivery configuration of the medical device is obtained, and the medical device is loaded into a restraining member. Preferably, the delivery configuration of the medical device includes stress-induced R-phase.

Claims

1. A method of loading a medical device into a delivery system, the method comprising:

providing a medical device comprising a two-stage shape memory alloy at a temperature at which at least a portion of the alloy is austenite;

applying a stress to the medical device at the temperature, the stress being sufficient to form R-phase from at least a portion of the austenite and not exceeding 200 MPa;

obtaining a delivery configuration of the medical device; and

loading the medical device in the delivery configuration into a restraining member, wherein the delivery configuration comprises stress-induced R-phase.

2. The method of claim 1 wherein the stress applied to the medical device is not sufficient to form martensite from the R-phase.

3. The method of claim 2 wherein the delivery configuration does not include stress-induced martensite.

4. The method of claim 1 wherein the stress-induced R-phase is present in the delivery configuration of the medical device in regions of maximum strain.

5. The method of claim 1 wherein the stress applied to the medical device is sufficient to form martensite from at least a portion of the R-phase.

6. The method of claim 5 wherein the delivery configuration of the medical device further comprises stress-induced martensite.

7. The method of claim 1 wherein the temperature is between about A_s and A_s+10°

C. of the shape memory alloy.

8. The method of claim 1 wherein the temperature is at or above A_f of the shape memory alloy, the alloy being fully austenitic at the temperature.

9. The method of claim 1 further comprising, prior to applying the stress to the medical device, processing the shape memory alloy to maximize a difference between a martensite start temperature and an R-phase start temperature of the alloy.

10. The method of claim 1 wherein applying the stress to the medical device comprises radially compressing the medical device and wherein the medical device is a self-expanding stent.

11. A method of loading a medical device into a delivery system, the method comprising:

providing a medical device comprising a two-stage shape memory alloy, the alloy being at a temperature at which the alloy includes a parent phase, the parent phase not being R-phase;

applying a stress of no more than 200 MPa to stress-induce the R-phase from the parent phase in at least a portion of the alloy at the temperature;

obtaining a delivery configuration of the medical device; and

loading the medical device in the delivery configuration into a restraining member, wherein the delivery configuration comprises stress-induced R-phase.

12. The method of claim 11, wherein the parent phase is austenite.

13. The method of claim 11, wherein the parent phase is martensite.

14. The method of claim 11, further comprising stress-inducing martensite from at least a portion of the stress-induced R-phase.

15. The method of claim 11, wherein the delivery configuration of the medical device further comprises stress-induced martensite.

16. The method of claim 11 further comprising, prior to applying the stress to the medical device, processing the shape memory alloy to maximize a difference between a martensite start temperature and an R-phase start temperature of the alloy.

17. A method of loading a medical device into a delivery system, the method comprising:

providing a medical device comprising a two-stage shape memory alloy at a temperature at which at least a portion of the alloy is austenite;

applying a stress to the medical device at the temperature, the stress being sufficient to form R-phase from at least a portion of the austenite;

obtaining a delivery configuration of the medical device; and

loading the medical device in the delivery configuration into a restraining member, wherein the delivery configuration comprises stress-induced R-phase,

wherein, prior to applying the stress to the medical device, the shape memory alloy is processed to maximize a difference between a martensite start temperature and an R-phase start temperature of the shape memory alloy.

18. A method of loading a medical device into a delivery system, the method comprising:

providing a medical device comprising a two-stage shape memory alloy, the alloy being at a temperature at which the alloy includes a parent phase, the parent phase not being R-phase;

stress-inducing the R-phase from the parent phase in at least a portion of the alloy at the temperature;

obtaining a delivery configuration of the medical device; and

loading the medical device in the delivery configuration into a restraining member, wherein the delivery configuration comprises stress-induced R-phase,

wherein, prior to stress-inducing the R-phase, the shape memory alloy is processed to maximize a difference between a martensite start temperature and an R-phase start temperature of the shape memory alloy.