Endovascular Implant Having an Integral Graft Component and Method of Manufacture

Abstract

A covered stent including an endovascular implant having a polymeric stent structure with an integrally formed membrane-like graft component, also referred to as a stent-graft, and methods of manufacturing the one-piece stent-graft by an injection molding process. A molding system for creating the polymeric stent structure is injected with a melt stream of moldable material that is forced between a parting line of the molding system to create a thin, flexible membrane-like structure within the open areas or interstitial spaces of the molded stent structure. The stent-graft so created is a one-piece, unified structure molded from a polymeric material in a single manufacturing step.

1 . A stent-graft for placement within a body vessel comprising:
 a tubular stent structure having a thin membrane-like structure covering spaces within the tubular stent structure and defining at least a portion of a blood flow lumen that extends longitudinally through the tubular stent structure, wherein the tubular stent structure and the thin membrane-like structure are a one-piece component of a polymeric material.   
     
     
         2 . The stent-graft of  claim 1 , wherein the tubular stent structure includes a plurality of frame members and the spaces are interstices formed between adjacent frame members. 
     
     
         3 . The stent-graft of  claim 1 , wherein the thin membrane-like structure is disposed proximate an interior side of the tubular stent structure. 
     
     
         4 . The stent-graft of  claim 3 , wherein the tubular stent structure substantially forms an exterior contact surface of the stent-graft that expands into apposition with a wall of the body vessel. 
     
     
         5 . The stent-graft of  claim 4 , wherein the tubular stent structure is balloon-expandable. 
     
     
         6 . The stent-graft of  claim 4 , wherein the tubular stent structure is self-expanding. 
     
     
         7 . The stent-graft of  claim 1 , wherein the thin membrane-like structure is substantially impermeable. 
     
     
         8 . The stent-graft of  claim 1 , wherein the polymeric material is polyoxymethylene. 
     
     
         9 . The stent-graft of  claim 1 , wherein the thin membrane-like structure has a thickness of approximately 0.001 inch. 
     
     
         10 . A method of manufacturing a one-piece stent-graft comprising:
 injecting a melt stream of moldable polymeric material into a mold cavity of a molding system, wherein the mold cavity forms a tubular stent framework having interstitial spaces;   filling the mold cavity with the melt until the mold cavity overflows and the melt flows between parting surfaces of the molding system; and   allowing the melt to cover the parting surfaces such that a molded tubular stent framework formed thereby has an integral thin membrane-like structure formed within the interstitial spaces thereof by the melt which has flowed between the parting surfaces.   
     
     
         11 . The method of  claim 10 , wherein the integral thin membrane-like structure has a thickness of approximately 0.0005 inch to 0.001 inch. 
     
     
         12 . The method of  claim 10 , wherein a gap of approximately 0.0005 inch is maintained between the parting surfaces of the molding system such that the integral thin membrane-like structure has a thickness of approximately 0.001 inch. 
     
     
         13 . The method of  claim 10 , wherein the moldable polymeric material is polyoxymethylene. 
     
     
         14 . The method of  claim 10 , wherein the mold cavity has a first portion in a first parting surface of the molding system and a second portion in a second parting surface of the molding system such that the integral thin membrane-like structure is formed within the interstitial spaces substantially midway between exterior and interior surfaces of the molded tubular stent framework.