Sheaths Reducing Recoil and Loss of Retention for Polymer Scaffolds Crimped to Balloons

• US 20140157567A1
• Filed: 12/07/2012
• Published: 06/12/2014
• Est. Priority Date: 12/07/2012
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Wang, Yunbing, Bayogo, Jhoan
• Granted Patent: US 9,072,590 B2
• Time in Patent Office: Days
• US Class Current: 29/428
• CPC Class Codes: A61F 2/0095 Packages or dispensers for prostheses or other implants for intraocular lenses A61F2/1691; for dental surgery A61C19/02
• CPC Class Codes: A61F 2/011 Instruments for their placement or removal
• 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 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2/962 having an outer sleeve
• CPC Class Codes: A61F 2/97 the outer sleeve being splittable
• CPC Class Codes: A61F 2002/9583 Means for holding the stent on the balloon, e.g. using protrusions, adhesives or an outer sleeve
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: A61F 2250/0059 temporary
• CPC Class Codes: B23P 11/005 by expanding or crimping
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 29/49838 by stringing
• CPC Class Codes: Y10T 29/49909 Securing cup or tube between axially extending concentric annuli
• CPC Class Codes: Y10T 29/49915 Overedge assembling of seated part

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. A single piece sheath is placed over the scaffold immediately following crimping of the scaffold to the balloon. The single piece sheath is replaced by a two-piece sheath, which is removed prior to performing a medical procedure using the medical device.

Claims

1. A method for assembling a medical device, comprising:

providing a catheter including a shaft and a balloon having distal and proximal ends;

disposing a temporary sheath on the catheter shaft;

crimping a polymer scaffold to the balloon while the sheath is disposed on the catheter shaft;

advancing the temporary sheath from the balloon proximal end towards the balloon distal end to radially constrain the crimped scaffold;

inspecting the crimped scaffold and/or balloon within the temporary sheath;

removing the temporary sheath from the crimped scaffold; and

placing a final sheath over the crimped scaffold.

2. The method of claim 1, wherein the scaffold is configured for being placed within a body only after the final sheath is removed.

3. The method of claim 1, wherein the catheter is sealed within packaging while the crimped polymer scaffold is disposed within the final sheath.

4. The method of claim 1, wherein the inspecting step includes increasing the pressure inside of the balloon, decreasing the pressure within the balloon then removing the temporary sheath from the crimped scaffold.

5. The method of claim 1, wherein the temporary sheath is made from a transparent material and the inspecting step includes at least visually inspecting the crimped scaffold while disposed within the temporary sheath.

6. The method of claim 1, wherein the temporary sheath is tubular having first and second ends, the first end is proximal the balloon proximal end and the second end is distal the balloon proximal end, and at least the second end is flared.

7. The method of claim 1, wherein the constraining step includes deforming a flared end of the temporary sheath to reduce resistance to a sliding of the temporary sheath over the crimped scaffold.

8. The method of claim 1, wherein both ends of the temporary sheath are flared and an end disposed adjacent the balloon has weakened portion to facilitate removal of the temporary sheath from the scaffold by tearing the temporary sheath at the weakened portion.

20. The method of claim 1, wherein the temporary sheath is positioned by restraining the catheter shaft while the temporary sheath is pulled towards the balloon distal end,

wherein the pulling step includes depressing a flared end of the temporary sheath so as to avoid shifting of balloon material while the temporary sheath is being positioned over the scaffold.

9. A method for assembling a medical device, comprising:

providing a catheter including a polymer scaffold crimped to a balloon; and

constraining the scaffold including placing a first sheath over the scaffold;

removing the first sheath from the scaffold; and

after removal of the first sheath, placing a second sheath over the scaffold.

10. The method of claim 9, wherein the second sheath

applies a radial inward force on the crimped scaffold to limit recoil of the scaffold,

extends distally of the catheter distal end by about a length equal to the length of the scaffold, and

wherein the medical device is configured for being passed through the body of a patient only after the second sheath is removed.

11. The apparatus of claim 10, wherein the sheath comprises a protecting sheath and a constraining sheath that is placed over the protecting sheath and the crimped scaffold to limit recoil of the scaffold by an applying an inwardly directed radial force on the crimped scaffold.

12. The apparatus of claim 10, wherein the protecting sheath includes a first and second separable half forming a proximal portion of the constraining sheath.

13. The method of claim 9, wherein the second sheath includes

a protecting portion disposed over the scaffold, the first portion including an extension that is distal of the catheter distal end;

and

a constraining portion disposed over the scaffold and applying a radial-inward force on the scaffold.

14. The apparatus of claim 9, wherein the scaffold is configured for being placed within a body only after the second sheath is removed.

21. The method of claim 9, wherein the first sheath is placed by restraining the catheter shaft while the first sheath is pulled towards the balloon distal end,

wherein the pulling step includes depressing a flared end of the first sheath so as to avoid shifting of balloon material while the first sheath is being placed over the scaffold.

15. A method for assembling a medical device, comprising:

providing a balloon catheter, a scaffold and a sheath disposed on a shaft of the balloon catheter between a catheter proximal end and a balloon proximal end;

crimping a polymer scaffold to the balloon-catheter;

positioning the sheath over the crimped scaffold including moving a distal end of the sheath towards a balloon distal end.

16. The method of claim 15, the sheath is a first sheath made from at least a semi-transparent material, further including the steps of

inspecting the scaffold and balloon within the first sheath,

after inspecting the scaffold, removing the first sheath from the scaffold, then placing a second sheath over the scaffold to minimize recoil of the scaffold,

wherein the medical device is configured for being passed through a body only after the second sheath is removed from the scaffold.

17. The method of claim 15, wherein the first sheath is tubular and has a weakened portion at a distal end thereof.

18. The method of claim 15, wherein the polymer has a lower end of a glass transition temperature TG-LOW and the crimping step includes heating the polymer to a temperature of about 5-15 degrees below TG-LOW.

19. The method of claim 15, wherein the scaffold is crimped using an iris-type crimper mechanism.

22. The method of claim 15, wherein the first sheath is positioned by restraining the catheter shaft while the sheath is pulled towards the balloon distal end,

wherein the pulling step includes depressing a flared end of the sheath so as to avoid shifting of balloon material when the temporary sheath is being positioned over the scaffold.

23. The method of claim 15, wherein the crimping step includes

inflating or over inflating the balloon then at least partially crimping the scaffold to the balloon, and

wherein the medical device is configured for being passed through a body only after the sheath is removed from the scaffold.

24. The method of claim 15, wherein prior to crimping, the scaffold has a first diameter that is greater than or equal to a fully or over-inflated balloon diameter.

25. A method for making a medical device, comprising:

providing a scaffold formed from a radially-expanded tube and having a pre-crimp diameter, the radially-expanded tube comprising a polymer;

crimping the scaffold to a balloon catheter, the scaffold being crimped from the pre-crimp diameter to a final diameter, the pre-crimp diameter being at least 2 times the final diameter;

placing the crimped scaffold within a first sheath by pulling the first sheath towards a distal end of the balloon catheter so that the crimped scaffold is disposed within the first sheath, the first sheath having a first diameter and a first radial stiffness sufficient to restrain recoil of the scaffold after crimping;

replacing the first sheath with a second sheath having a second diameter and a second radial stiffness, the second sheath capable of being removed from a scaffold by a medical professional;

wherein the scaffold is configured for being placed within a body only after the second sheath is removed from the crimped scaffold; and

wherein the first diameter is less than the second diameter and/or the first radial stiffness is greater than the second radial stiffness.