Method of crimping stent on catheter delivery assembly

Patent metadata

Field	Value
Publication number	US-9763818-B2
Application number	US-201314085716-A
Country	US
Kind code	B2
Filing date	Nov 20, 2013
Priority date	Jan 30, 2010
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A method of crimping a stent is disclosed. The stent includes a minimum crimped diameter such that in the minimum crimped diameter, a pair of stent rings, between which marker support structures reside, do not make contact with the marker support structures. The crimped profile of the stent of the present invention can be as small as the crimped profile of a same stent but without the maker support structures.

First claim

The invention claimed is:

1. A method of crimping a stent on a catheter delivery assembly, the method comprising:
(a) positioning a polymeric stent over a section of a catheter delivery assembly, wherein the stent comprises:
(i) a set of rings including a proximal end ring, a distal end ring opposing the proximal end ring, and middle rings positioned between the end rings, wherein each ring is associated with its direct neighboring ring by links, and wherein at least one pair of neighboring middle rings can be delineated, via corresponding links there between, into closed cells comprising a W- or a general W-shaped zone included within the closed cell;
(ii) at least one of the links being a marker link, the marker link having a first cylindrical or part-cylindrical protrusion off a first side wall of the marker link for holding a first marker and a second cylindrical or part-cylindrical protrusion off a second, opposite side wall of the marker link for holding a second marker, wherein a distance of the first marker from an end point of the marker link is equal to the distance of the second marker from the same end point of the marker link such that the first and second protrusions are symmetrically aligned off of the marker link and are not longitudinally off-set from one another off of the marker link; and
(iii) wherein the set of rings includes a minimum crimped diameter such that in the minimum crimped diameter, a pair of rings, between which the marker link resides, do not make contact with a bulging perimeter of the first and second protrusions;

and
(b) crimping the stent to a crimped diameter on the section of the catheter delivery assembly, wherein the crimping includes heating the polymeric stent to a target temperature, whereby the pair of rings, between which the marker link resides, do not make contact with the bulging perimeter of the first and second protrusions in the crimped diameter.

2. The method of claim 1 , wherein the target temperature is less than a glass transition temperature of a polymer of the stent during the crimping.

3. The method of claim 1 , wherein the target temperature is 5 to 10 degrees below the glass transition temperature of a polymer of the stent.

4. The method of claim 1 , wherein the minimum crimped diameter is less than the crimped diameter.

5. The method of claim 1 , wherein the stent is crimped on a balloon of the catheter delivery assembly such that during crimping the balloon is in an inflated state to apply a radially outward pressure to the stent while the stent is being crimped.

6. The method of claim 5 , wherein an inflation pressure in the balloon is adjusted during crimping as the diameter of the stent is reduced.

7. The method of claim 1 , additionally including, during crimping, preventing or minimizing irregular bending or twisting of the rings and/or links.

8. The method of claim 1 , wherein the crimping step comprises use of sheet(s) of a polymer film between the stent and blades of a crimping apparatus.

9. The method of claim 1 , wherein the crimping step comprise:
(a) a pre-crimping step or an initial diameter reduction;
(b) a re-alignment of the stent or alignment check of the of the stent; and
(c) a final crimping step on a balloon of the catheter delivery assembly.

10. The method of claim 1 , additionally comprising de-ionizing the stent before and/or during the crimping step.

11. The method of claim 1 , wherein the heating step is performed by application of hot air.

12. The method of claim 1 , wherein the crimping step comprises using a crimping apparatus having crimping elements which apply pressure to the stent to reduce the diameter of the stent, the crimping elements being at least partially coated with a polymer.

13. The method of claim 1 , wherein crimping is performed by a crimping apparatus having crimping elements that have rounded or blunt edges or tips for preventing or reducing damage to the rings and links when the crimping elements make contact with the stent for reducing the diameter of the stent.

14. The method of claim 1 , wherein at least one of the closed cells is immediately abutted against 6 neighboring closed cells.

15. The method of claim 1 ,
wherein the rings include crowns and struts, each link adjoining a pair of the neighboring rings at a crown of each ring, and
wherein the minimum crimped diameter (MCD) is equal to the value derived from equation 1 or equation 2:
MCD=(Σ Swi+ΣCrj+ΣLwk )*(π) −1 +2*WT  (equation 1)

MCD=(Σ Swi+ΣCrj+ΣLwk )*(π) −1   (equation 2)

such that
ΣSwi (i=1 . . . n) is the sum of n ring struts having width Swi;
ΣCrj (j=1 . . . m) is the sum of m crown inner radii having radii Crj (times 2);
ΣLwk (k=1 . . . p) is the sum of p links having width Lwk; and
WT is a ring wall thickness.

16. The method of claim 15 , wherein each ring has an aspect ratio (AR) of 0.8 to 1.4, AR being defined as ratio of width to thickness.

17. The method of claim 16 , wherein each link has an AR of 0.4 to 0.9.

18. The method of claim 1 ,
wherein the rings include crowns and struts, each link adjoining a pair of the neighboring rings at a crown of each ring, and
wherein the minimum crimped diameter (MCD) is less than the value derived from equation 1 or equation 2:
MCD≦(Σ Swi+ΣCrj+ΣLwk )*(π) −1 +2*WT  (equation 1)

MCD≦(Σ Swi+ΣCrj+ΣLwk )*(π) −1   (equation 2)

such that
ΣSwi (i=1 . . . n) is the sum of n ring struts having width Swi;
ΣCrj (j=1 . . . m) is the sum of m crown inner radii having radii Crj (times 2);
ΣLwk (k=1 . . . p) is the sum of p links having width Lwk; and
WT is a ring wall thickness.

19. The method of claim 18 , wherein each ring has an aspect ratio (AR) of 0.8 to 1.4, AR being defined as ratio of width to thickness.

20. The method of claim 19 , wherein each link has an AR of 0.4 to 0.9.

21. The method of claim 1 , wherein the marker link is longer than the links which do not have a marker.

22. The method of claim 1 , wherein the rings have crowns and the crowns have a crown angle of less than 115 degrees.

23. The method of claim 1 , wherein the rings have crowns such that a pre-crimped crown angle is greater than a deployment crown angle.

24. The method of claim 1 , wherein the first protrusion and the second protrusion including the first and second markers are circumferentially off-set from the marker link and spaced from the pair of rings associated with the marker link.

25. The method of claim 1 , wherein each pair of neighboring middle rings forms only 4 closed cell, the cells being W- or general W-shaped.

26. The method of claim 1 , wherein the middle rings comprise a network of circumferentially positioned closed cells and longitudinally positioned closed cells, the circumferentially positioned closed cells can be numbered 1 to n, and the longitudinally positioned closed cells can be numbered 1 to m, such that the odd numbered longitudinally positioned closed cells are in phase with each other, the even numbered longitudinally positioned closed cells are in phase with each other, and the odd numbered cells and even numbered cells are out of phase with each other.

27. The method of claim 26 , wherein n is 4.

28. The method of claim 1 ,
wherein at least one pair of the neighboring middle rings is adjoined by middle links, each middle link is associated with one crown of one

Assignees

• Abbott Cardiovascular Systems Inc

Inventors

• Trollsas Mikael
• Ngo Michael H
• Anukhin Boris
• Nikanorov Alexander
• Hossainy Syed
• Papp John E
• Jayasinghe Dudley
• Solter Zella

Classifications

• A61F2210/0019

  operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation · CPC title

• A61F2250/0067

  Means for introducing or releasing pharmaceutical products into the body · CPC title

• A61F2250/0096

  Markers and sensors for detecting a position or changes of a position of an implant, e.g. RF sensors, ultrasound markers · CPC title

• A61F2210/0014

  using shape memory or superelastic materials, e.g. nitinol · CPC title

• A61F2250/0098

  radio-opaque, e.g. radio-opaque markers · CPC title