Methods for improving stent retention on a balloon catheter
A method of crimping a stent on a balloon of a catheter assembly is provided. A polymeric stent is disposed over a balloon in an inflated configuration. The stent is crimped over the inflated balloon to a reduced crimped configuration so that the stent is secured onto the balloon. The balloon wall membrane is wedged or pinched between the strut elements of the stent for increasing the retention of the stent on the balloon.
1. A method of crimping a stent on a balloon, comprising the following acts in the order as listed:
(a) providing a poly (L-lactide) stent disposed over a balloon in an inflated configuration, the balloon being inflated by a fluid at a temperature of a glass transition temperature (T g ) of the poly (L-lactide) stent;
(b) crimping the stent to a first reduced diameter;
(c) at least partially deflating the balloon;
(d) inflating the balloon to at least an inner diameter of the stent; and
(e) crimping the stent to a second reduced diameter.
2. The method of claim 1 , wherein the second reduced diameter is a final crimped diameter.
3. The method of claim 2 , additionally comprising, following act (e):
(f) at least partially deflating the balloon; followed by
(g) inflating the balloon to at least an inner diameter of the stent; followed by
(e) crimping the stent to a third reduced diameter.
4. The method of claim 3 , wherein the third reduced diameter is a final crimped diameter.
5. A stent-balloon catheter assembly made in accordance with the method of claim 1 .
6. The method of claim 1 , wherein a balloon softening fluid is applied to the balloon.
7. The method of claim 1 , wherein a solvent is applied to the balloon surface.
8. The method of claim 1 , wherein the crimping is performed using a crimper.
9. The method of claim 8 , wherein the crimper is an iris crimper.
10. The method of claim 8 , wherein the crimper includes jaws configured to move inward.
11. The method of claim 1 , wherein the crimping of steps (b) and (d) include radially compressing the stent between jaws of a crimper.
12. The method of claim 1 , wherein the stent is in a crimping device for steps (b) and (d).
13. The method of claim 12 , wherein the balloon is inflated before being placed in the crimping device.
14. The method of claim 1 , wherein prior to step (c) the balloon has a crimp inflation state that is greater than a collapsed state of the balloon.
15. The method of claim 1 , wherein subsequent to crimping the stent to the second reduced diameter a membrane or wall of the balloon is pinched or wedged between structural elements of the stent.
16. The method of claim 1 , wherein during at least step (b) the pressure in the balloon is controllably released by a valve.