Stents and stent grafts having enhanced hoop strength and methods of making the same

• US 5,968,091 A
• Filed: 11/26/1997
• Issued: 10/19/1999
• Est. Priority Date: 03/26/1996
• Status: Expired due to Term

• Current Assignee: Lifeshield Sciences LLC (Acacia Research Corporation)
• Original Assignee: Corvita Corporation (Boston Scientific Corporation)
• Inventors: Frid, Noureddine, Pinchuk, Leonard
• Primary Examiner(s): Yu, Mickey
• Assistant Examiner(s): Nguyen, Tram A.
• Application Number:
  US08/979,278
• Time in Patent Office: 692 Days
• Field of Search: 623/1, 623/11, 623/12, 606/191, 606/194, 606/195, 606/198, 600/36, 427/2.1, 427/2.24
• US Class Current: 623/1.16
• CPC Class Codes: A61F 2/0077 Special surfaces of prostheses, e.g. for improving ingrowth A61F2/30767 takes precedence
• CPC Class Codes: A61F 2/07 Stent-grafts
• 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 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes

Abstract

Stents are coated with a polymer such that the polymeric coating binds the crossover points of the wires, or, in the case of a zig-zag stent, binds adjacent zig-zags of wires without occluding the interstices of the stent lattice. Suitable polymers include polyurethane, polycarbonate urethane, polyurethane urea, silicone rubber, polyisobutylene copolymer (with styrene, etc.), polyolefin, polyester, glycolated polyester, polyamide, amorphous polyamide, combinations of the above and the like. Biodegradable polymers such as polyisobuterate, polyvalerate, polylactic acid, polyglycolic acid and combinations of these are also suitable. The polymer can be reacted in place without a solvent, such as two component polyurethanes, or silicone rubbers, or the reacted polymer can be dissolved in an appropriate solvent, for example, dimethylacetamide for the polyurethanes, toluene for the polyolefins, or heptane for the silicone rubbers. In order to enhance bonding of the polymer to the stent wires, the metallic stent can be primed prior to coating. The hoop strength of a polymer coated stent is improved due to locking of the crossover points and preventing free motion of the stent wires relative to each other.

Claims

1. A prosthesis comprising:

a) a radially and axially flexible substantially cylindrical body formed from a plurality of wire filaments having crossing points defining a lattice of interstices between wire filaments, said wire filaments being coated with a polycarbonate urethane polymer having a melting point of approximately 240°

C. substantially continuously alone substantially their entire lengths and at said crossing points so that said wire filaments are bound to each other by said polymer at said crossing points and said interstices of said lattice are not substantially occluded by said polymer; and

b) a porous vascular graft attached to said body, said porous vascular graft comprising a spun polycarbonate urethane liner having a melting point of approximately 160°

C.

2. A prosthesis comrising:

a radially and axially flexible substantially cylindrical body formed from a plurality of wire filaments having crossing points defining a lattice of interstices between wire filaments, said wire filaments being coated with a polymer at said crossing points so that said wire filaments are bound to each other by said polymer at said crossing points and said interstices of said lattice are not substantially occluded by said polymer, wherein

said wire filaments are coated by applying a polymeric solution containing a biodegradable mixture of polybuterate and polyvalerate dissolved in chloroform to the crossing points and allowing said polymeric solution to cure such that said crossing points are bound to each other by said polymer.

3. A prosthesis comprising:

a radially and axially flexible substantially cylindrical body formed from a plurality of wire filaments having crossing points defining a lattice of interstices between wire filaments, said wire filaments being coated with a polymer at said crossing points so that said wire filaments are bound to each other by said polymer at said crossing points and said interstices of said lattice are not substantially occluded by said polymer, wherein

said wire filaments are coated by dipping said substantially cylindrical body in a priming solution of 2% aminopropylaminoethyltrimethoxysilane dissolved in a substantially 95%/5% mixture of ethanol and water, substantially drying the dipped cylindrical body, and then applying a polymeric solution to said crossing points and allowing said polymeric solution to cure such that said crossing points are bound to each other by said polymer.