Expandable medical device with differential hinge performance

• US 20060122688A1
• Filed: 11/02/2005
• Published: 06/08/2006
• Est. Priority Date: 12/08/2004
• Status: Active Grant

• Current Assignee: Innovational Holdings, LLC
• Original Assignee: Conor Medsystems Incorporated
• Inventors: Shanley, John F., Fisher, Beau M.
• Granted Patent: US 7,429,268 B2
• Time in Patent Office: Days
• US Class Current: 623/1.150
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91541 Adjacent bands are arranged out of phase
• CPC Class Codes: A61F 2002/91558 connected peak to peak
• CPC Class Codes: A61F 2230/0054 V-shaped
• CPC Class Codes: A61F 2250/0036 differing in thickness
• CPC Class Codes: A61F 2250/0068 the pharmaceutical product being in a reservoir

Abstract

The stent described herein is configured with expandable rings at either end of the stent having increased radial strength compared to the expandable middle rings. This difference between the configuration of the stent at the middle and ends of the stent results in more even expansion properties of the stent, better crimping properties of the stent, and uniform diameter post deployment. The expandable rings are formed by a plurality of struts and a plurality of ductile hinges arranged such that upon expansion, the ductile hinges are deformed while the struts are not deformed.

Claims

1. An expandable medical device comprising:

at least one middle expandable ring formed of a plurality of substantially rigid struts interconnected by deformable ductile hinges;

two end expandable rings located one at each opposite axial end of the expandable medical device and interconnected to the at least one middle expandable ring by flexible connecting elements, the end expandable rings formed of a plurality of substantially rigid struts interconnected by deformable ductile hinges;

wherein the ductile hinges of the at least one middle expandable ring have a hinge width less than a hinge width of the ductile hinges of the end expandable rings.

2. The device of claim 1, wherein at least two end expandable rings and the at least one middle expandable ring are formed in S-shaped or Z-shaped patterns.

3. The device of claim 2, wherein two ductile hinges are located adjacent each bend in the S-shaped or Z-shaped patterns.

4. The device of claim 1, wherein the ductile hinges each have a hinge width which is less than adjacent struts, and the hinges have a hinge length which is less than adjacent struts.

5. The device of claim 1, wherein the ductile hinges are designed to deform plastically upon radial expansion or compression of the expandable medical device while the struts experience no plastic deformation upon radial expansion or compression.

6. The device of claim 1, wherein the ductile hinges of the at least one middle expandable ring have a hinge width about 5% to about 50% less than a hinge width of the ductile hinges of the end expandable rings.

7. The device of claim 1, wherein the ductile hinges of the at least one middle expandable ring have a hinge width about 5% to about 25% less than a hinge width of the ductile hinges of the end expandable rings.

8. The device of claim 2, wherein the flexible connecting elements interconnect the end expandable rings to the middle expandable rings adjacent the bends in the S-shaped or Z-shaped patterns.

9. The device of claim 1, wherein the substantially rigid struts of the end expandable rings and the middle expandable rings have a strut width which is substantially the same.

10. The device of claim 1, wherein the ductile hinges of the end expandable rings have a width about 45% to about 55% less than a width of the substantially rigid struts of the end expandable rings.

11. The device of claim 1, wherein the ductile hinges of the middle expandable rings have a width of about 50% to about 60% less than a width of the substantially rigid struts of the middle expandable rings.

12. The device of claim 1, wherein the end expandable rings having the larger width ductile hinges each have a length which is about 3% to about 30% of an overall length of the expandable medical device.

13. A method of improving crimping of stents onto balloons, the method comprising:

forming a stent with a plurality of struts and a plurality of ductile hinges, wherein the ductile hinges are designed to deform plastically upon radial expansion or compression of the stent while the struts experience substantially no plastic deformation upon radial expansion or compression;

forming a portion of the plurality of ductile hinges located at axial ends of the stent with a larger width than a remainder of the plurality of ductile hinges;

crimping the stent onto a balloon catheter by compressing the stent to a uniform crimped diameter along the axis of the stent; and

releasing the compressive force of crimping and causing the stent to recoil a first percentage at the axial ends of the stent and a second percentage at a middle portion of the stent, wherein the second percentage is greater than the first percentage.

14. The method of claim 13, wherein each of the axial ends of the stent with the larger width ductile hinges extend for about 3% to about 30% of the length of the stent.

15. The method of claim 13, wherein a crimped diameter of the axial ends is at least 5% less than a crimped diameter of the middle portion of the stent.

16. A stent and delivery system comprising:

a balloon catheter;

a stent crimped onto the balloon catheter, wherein a crimped center portion of the stent has a first diameter which is greater than second and third diameters of opposite end portions of the stent.

17. The stent and delivery system of claim 16, wherein the second and third diameters are at least 5% less than the first diameter.

18. The stent and delivery system of claim 16, wherein the stent is formed with a plurality of ductile hinges, and wherein a portion of the plurality of ductile hinges located at axial ends of the stent have a larger width than a remainder of the plurality of ductile hinges.