Reducing crimping damage to polymer scaffold

• US 8,539,663 B2
• Filed: 08/23/2010
• Issued: 09/24/2013
• Est. Priority Date: 08/23/2010
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Wang, Yunbing, Vazquez, Luis, Nguyen, Hung T., Mueller, Scott H., Yan, Kathleen
• Primary Examiner(s): Hong, John C
• Application Number:
  US12/861,719
• Publication Number:
  US 20120042501A1
• Time in Patent Office: 1,128 Days
• Field of Search: 295/05, 292/835, 295/15, 295/16, 295/23, 623/1.15, 623/1.16
• US Class Current: 29/505
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• 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 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2002/91566 connected trough to trough
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: B29C 53/30 of tubes by blow-moulding B29C49/00
• CPC Class Codes: B29C 67/0014 for shaping tubes or blown tubular films
• CPC Class Codes: B29D 23/00 Producing tubular articles B29D24/00 takes precedence
• CPC Class Codes: B29D 23/001 Pipes; Pipe joints pleated hoses B29D23/18
• CPC Class Codes: Y10T 29/49908 Joining by deforming
• CPC Class Codes: Y10T 29/49925 Inward deformation of aperture or hollow body wall
• CPC Class Codes: Y10T 29/49927 Hollow body is axially joined cup or tube
• CPC Class Codes: Y10T 29/4994 Radially expanding internal tube
• CPC Class Codes: Y10T 29/49945 by driven force fit
• CPC Class Codes: Y10T 29/53996 by deforming

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold is crimped to the catheter by a multi-step process for increasing scaffold-catheter yield following a crimping sequence. Damage reduction during a crimping sequence includes modifying blades of a crimper, adopting a multi-step crimping sequence, and inflating a supporting balloon to support the scaffold during crimping.

Claims

1. A method for crimping a polymer scaffold to a balloon, comprising:

placing a scaffold having a first diameter on a support balloon;

inflating the support balloon to a pressure for supporting and stabilizing the scaffold at the first diameter while the scaffold is being crimped;

crimping the scaffold from the first diameter to a second diameter while the scaffold is supported by the support balloon;

replacing the support balloon with a balloon catheter after the scaffold is reduced to the second diameter; and

crimping the scaffold to a third diameter, less than the second diameter while the scaffold is supported by the balloon catheter.

2. The method of claim 1, wherein the support balloon is a compliant balloon and the catheter balloon is a non-compliant balloon.

3. The method of claim 1, wherein the scaffold first diameter is greater than the fully deployed diameter of the catheter balloon.

4. The method of claim 1, wherein the scaffold is disposed between polymer sheets when crimped.

5. The method of claim 1, wherein the scaffold is heated and contacted by crimper blades coated with a polymer for softening the crimper blades.

6. The method of claim 1, further including the step of rotating the scaffold about the support balloon following a first crimping using the support balloon, reducing the diameter of the scaffold, then replacing the support balloon with the balloon catheter so as to produce a more uniform crimping of the scaffold about the circumference of the scaffold.

7. The method of claim 1, wherein a ratio of the first diameter to the third diameter is between 2.5 and 3.0.

8. The method of claim 1, further including heating the scaffold, wherein during both crimping steps the scaffold has a temperature of between 5 and 10 degrees below a glass transition temperature (Tg) of the polymer.

9. The method of claim 8, wherein the polymer is poly(L-lactide) (PLLA) or poly(lactic-glycolic acid) (PLGA),

wherein when the polymer is PLLA the temperature is raised to about 48 deg. Celsius, and

wherein when the polymer is PLGA the temperature is raised to a temperature less than 48 deg. Celsius.

10. The method of claim 1, further including heating the scaffold, wherein during both crimping steps the scaffold has a temperature of between 48 and 54 Degree Celsius and the polymer is poly(L-lactide).

11. The method of claim 1, wherein the scaffold has a first diameter of 3.5 mm and a length of 18 mm.

12. The method of claim 1, wherein the scaffold has a first diameter of 9 mm and after being crimped to the balloon catheter the scaffold diameter is 2-3 mm.

13. The method of claim 1, further including the step of placing a restraining sheath over the scaffold after the scaffold is crimped to the balloon catheter.

14. The method of claim 1, wherein he crimping the scaffold from the first diameter to a second diameter includes a crimping rate of 0.005 in/sec.

15. The method of claim 1, further including the step of deionizing the scaffold before crimping the scaffold to the balloon catheter.

16. A method for crimping a polymer scaffold to a balloon catheter, comprising:

placing a scaffold having a first diameter on a support balloon;

inflating the support balloon to a pressure for supporting and stabilizing the scaffold at the first diameter while the scaffold is being crimped;

crimping the scaffold from the first diameter to a second diameter while the scaffold is supported by the support balloon;

replacing the support balloon with the balloon catheter after the scaffold is reduced to the second diameter; and

crimping the scaffold to the balloon catheter.

17. The method of claim 16, wherein the second diameter is ½

the first diameter.

18. The method of claim 16, wherein the catheter balloon is inflated and deflated when crimping the scaffold to the balloon catheter.