Methods for Making an Encapsulated Stent

Abstract

A method for making an encapsulated stent includes providing first and second ePTFE layers and a stent positioned therebetween. The first ePTFE layer may be unsintered and have a node-fibril microstructure in which the fibrils are oriented perpendicular to the longitudinal axis. The second ePTFE layer may be unsintered and have a node-fibril microstructure in which the fibrils are oriented parallel to the longitudinal axis. The method includes joining the first ePTFE layer to the second ePTFE layer through openings in a wall of the stent.

What is claimed is: 
     
         1 . A method for making an encapsulated stent, comprising:
 providing a mandrel having a longitudinal axis;   providing a first unsintered ePTFE layer having a node-fibril microstructure in which the fibrils are oriented perpendicular to the longitudinal axis;   disposing the first ePTFE layer about the mandrel;   providing a second unsintered ePTFE layer having a node-fibril microstructure in which the fibrils are oriented parallel to the longitudinal axis;   disposing the second ePTFE layer about the mandrel;   positioning a stent between the first and second ePTFE layers to form an assembly; and   joining the first ePTFE layer to the second ePTFE layer through openings in a wall of the stent.   
     
     
         2 . The method according to  claim 1 , further comprising disposing an ePTFE interlayer member between the first and second ePTFE layers. 
     
     
         3 . The method according to  claim 2 , wherein the disposing an ePTFE interlayer member includes positioning the ePTFE interlayer member adjacent an abluminal surface of the stent. 
     
     
         4 . The method according to  claim 2 , wherein the disposing an ePTFE interlayer member includes positioning the ePTFE interlayer member adjacent a luminal surface of the stent. 
     
     
         5 . The method according to  claim 2 , wherein the ePTFE interlayer member comprises a plurality of ring shaped members, the disposing step including positioning the ring shaped members along the longitudinal axis in spaced relation from one another. 
     
     
         6 . The method according to  claim 2 , wherein the disposing an ePTFE interlayer member includes wrapping a sheet of unsintered ePTFE material about the mandrel. 
     
     
         7 . The method according to  claim 2 , further comprising the step of inserting a radiopaque marker between the first and second ePTFE layers, the disposing an ePTFE interlayer member including positioning the ePTFE interlayer member between the radiopaque marker and the stent. 
     
     
         8 . The method according to  claim 2 , wherein the ePTFE interlayer member has a node-fibril microstructure in which the fibrils are parallel to the longitudinal axis. 
     
     
         9 . The method according to  claim 1 , wherein the joining includes applying pressure by wrapping a tape over the assembly under tension and applying heat to sinter the first and second ePTFE layers. 
     
     
         10 . The method according to  claim 1 , wherein the disposing the first ePTFE layer about the mandrel includes contacting the mandrel with an inner surface of the first ePTFE layer. 
     
     
         11 . The method according to  claim 10 , wherein the disposing the second ePTFE layer about the mandrel includes contacting an abluminal surface of the stent with an inner surface of the second ePTFE layer. 
     
     
         12 . The method according to  claim 1 , wherein the disposing the second ePTFE layer about the mandrel includes contacting the mandrel with an inner surface of the second ePTFE layer. 
     
     
         13 . The method according to  claim 12 , wherein the disposing the first ePTFE layer about the mandrel includes contacting an abluminal surface of the stent with an inner surface of the first ePTFE layer. 
     
     
         14 . A method for making an encapsulated stent, comprising:
 providing a mandrel having a longitudinal axis;   providing a first unsintered ePTFE layer having a node-fibril microstructure in which the fibrils are oriented parallel to the longitudinal axis;   disposing the first ePTFE layer about the mandrel;   providing a second unsintered ePTFE layer having a node-fibril microstructure in which the fibrils are oriented parallel to the longitudinal axis;   disposing the second ePTFE layer about the mandrel;   wrapping a sheet of unsintered ePTFE material about the mandrel between the first and second ePTFE layers, the sheet of ePTFE material having a node-fibril microstructure in which the fibrils are oriented perpendicular to the longitudinal axis;   positioning a stent between the first and second ePTFE layers to form an assembly; and   joining the first ePTFE layer to the second ePTFE layer through openings in a wall of the stent.   
     
     
         15 . The method according to  claim 14 , wherein the disposing the first ePTFE layer about the mandrel includes contacting the mandrel with an inner surface of the first ePTFE layer, and wherein the wrapping a sheet of ePTFE material includes contacting an outer surface of the first ePTFE layer with an inner surface of the sheet of ePTFE material. 
     
     
         16 . The method according to  claim 14 , wherein the sheet of ePTFE material comprises a plurality of ring shaped members, the wrapping including positioning the ring shaped members along the longitudinal axis in spaced relation from one another. 
     
     
         17 . The method according to  claim 14 , further comprising the step of inserting a radiopaque marker between the first and second ePTFE layers, the wrapping a sheet of ePTFE material including positioning the sheet of ePTFE material between the radiopaque marker and the stent. 
     
     
         18 . The method according to  claim 14 , wherein the joining includes applying pressure by wrapping a tape over the assembly under tension and applying heat to sinter the first and second ePTFE layers.