Crush Recoverable Polymer Scaffolds Having a Low Crossing Profile

• US 20110190872A1
• Filed: 01/27/2011
• Published: 08/04/2011
• Est. Priority Date: 01/30/2010
• Status: Active Grant

• Current Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Original Assignee: Abbott Cardiovascular Systems Incorporated (Abbott Laboratories)
• Inventors: Hossainy, Syed, Anukhin, Boris, Trollsas, Mikael, Papp, John, Ngo, Michael H.
• Granted Patent: US 8,808,353 B2
• Time in Patent Office: Days
• US Class Current: 623/1.16
• 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 2/89 the wire-like elements comprising two or more adjacent rings flexibly connected by separate members
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91508 the meander having a difference in amplitude along the band
• CPC Class Codes: A61F 2002/91575 connected peak to trough
• CPC Class Codes: A61F 2240/002 Designing or making customized prostheses
• CPC Class Codes: A61M 25/1034 Joining of shaft and balloon
• CPC Class Codes: B23P 11/005 by expanding or crimping
• CPC Class Codes: B29C 55/24 radial
• CPC Class Codes: B29C 69/00 Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore B29C48/001 takes precedence
• CPC Class Codes: Y10T 29/49908 Joining by deforming

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold, after being deployed by the balloon, provides a crush recovery of about 90% after the diameter of the scaffold has been pinched or crushed by 50%. The scaffold also has a reduced crimped profile and a modification of the scaffold'"'"'s ring structure at the crowns that contributes to the reduced crimped profile.

Claims

1. A medical device implantable within a peripheral vessel of the body, comprising:

a scaffold formed from a polymer tube

configured for being crimped to a balloon,

the scaffold having a pattern of interconnected elements and

the scaffold having an expanded diameter when expanded from a crimped state by the balloon,

wherein the scaffold attains greater than about 80% of its expanded diameter after being crushed to at least about 75% of its expanded diameter.

2. The medical device of claim 1, wherein the scaffold attains greater than about 80% of its expanded diameter after being crushed to about 50% of its expanded diameter.

3. The medical device of claim 1, wherein the scaffold attains greater than about 80% of its expanded diameter after being crushed to about 67% of its expanded diameter.

4. The medical device of claim 2, wherein the scaffold pattern includes a symmetric closed cell having a plurality of crowns, wherein any of the crowns have a maximum crown angle of between about 90 degrees and 115 degrees when the scaffold has the expanded diameter.

5. The medical device of claim 1, wherein a crown has an inner radius of about 0 inches.

6. The medical device of claim 5, wherein the scaffold is cut from the polymer tube by a laser having a curl width, wherein the crown inner radius is about equal to the curl width of the laser.

7. The medical device of claim 2, wherein the scaffold is formed from a PLLA tube.

8. The medical device of claim 1, wherein the scaffold includes a plurality of zig-zag rings connected by links that extend parallel to a bore axis of the scaffold.

9. The medical device of claim 8, wherein the links include a U-shaped portion.

10. The medical device of claim 8, wherein the links include a U-shaped and an inverted U-shaped link.

11. The medical device of claim 8, wherein the links include S-shaped links.

12. The medical device of claim 8, wherein the links include a first, substantially-weakened portion defining a first moment of inertia (MOI) in bending and a second portion having a second MOI, wherein the first MOI is substantially less than the second MOI.

13. The medical device of claim 11, wherein the link is connected at a first end to a Y-crown of a ring and at a second end to a W-crown of the ring and the cross-section having the first MOI is closest to the Y-crown.

22. The medical device of claim 1, the interconnected elements forming a pattern, the pattern comprising

a plurality of rings, each of which formed by a plurality of closed cells, and each cell includes a first and second longitudinal element extending between first and second longitudinally-spaced bending elements, and

a connecting link connecting adjacent rings, wherein the moment of inertia (MOI) of the connecting link is substantially less than the MOI of the longitudinal element.

23. The medical device of claim 22, wherein the closed cell is symmetric about each of two orthogonal axes.

24. The medical device of claim 1, the interconnected elements forming a pattern, the pattern comprising

a plurality of rings, each of which being formed by a plurality of closed cells extending about a circumference of the scaffold, and

a connecting link connecting adjacent rings, wherein the connecting link includes a section forming a void, wherein the structure forming the void is such as to induce fracture in the polymer material forming the connecting link before fracture occurs in the crown of a ring when the scaffold is subject to repeated bending in a peripheral vessel.

25. The medical device of claim 1, wherein the scaffold expanded diameter is equal to, or greater than about 6 mm, a wall thickness of greater than about 0.008 inches, a radial strength greater than about 0.3 N/mm and a radial stiffness greater than or equal to about 0.5 N/mm.

14. A medical device for being implanted within a peripheral vessel of the body, comprising:

a scaffold formed from a polymer tube

crimped to a balloon,

the scaffold having a network of interconnected elements and

the scaffold having an expanded diameter when expanded from a crimped state to an expanded state by the balloon;

wherein the scaffold attains greater than about 80% of its expanded diameter after being crushed to about 50% of its expanded diameter; and

wherein the crimped scaffold has a crimped diameter of about equal to or less than a theoretical minimum diameter for the crimped scaffold.

15. A medical device, comprising:

a polymer scaffold crimped to a balloon and when expanded by the balloon having an expanded diameter;

wherein the crimped scaffold has a pattern of interconnected elements including a plurality of closed cells that are symmetric about two orthogonal axes; and

wherein the scaffold is capable of regaining more than about 80% of its expanded diameter after being crushed to about 50% of its expanded diameter.

16. The medical device of claim 15, wherein the crimped scaffold has material properties comprising:

a radially expanded polymer tube formed into a pre-crimped scaffold using a laser, and

the pre-crimped scaffold has a diameter at least 300% greater than a diameter of the crimped scaffold, and

the pattern of interconnected elements includes a plurality of rings, wherein a ring is connected to an adjacent ring by no more than four linear connecting links.

17. A method of making a medical device for implanting in a peripheral artery, comprising:

radially expanding a cylindrical, polymer tube;

forming the scaffold from the tube including forming a crown having an inner radius of about 0 inches; and

crimping the scaffold to a balloon catheter.

18. The method of claim 17, further including crimping the scaffold to a diameter less than a theoretical minimum diameter for the scaffold.

19. The method of claim 18, wherein the theoretical minimum diameter is at least 300% less than a pre-crimp diameter.

20. The method of claim 19, wherein the scaffold is formed from PLLA.

21. The method of claim 20, wherein the scaffold is crimped at a temperature 5 to 10 degrees less than about the glass transition temperature of the expanded tube.