Electrospun ptfe coated stent and method of use

Abstract

A stent or other prosthesis may be formed by coating a single continuous wire scaffold with a polymer coating. The polymer coating may consist of layers of electrospun polytetrafluoroethylene (PTFE). Electrospun PTFE of certain porosities may permit endothelial cell growth within the prosthesis.

1 . A stent, comprising; 
 a coating, the coating comprising: 
 an inner layer of electrospun polytetrafluoroethylene (PTFE) fibers; 
 an outer layer of electrospun PTFE fibers, and 
 a non-electrospun tie layer disposed between the inner layer of electrospun 
   PTFE fibers and the outer layer of electrospun PTFE fibers,   wherein the inner layer of electrospun PTFE fibers has an average pore size configured to permit growth of endothelial cells on a surface of the stent and the non-electrospun tie layer is impermeable to tissue growth.   
     
     
         2 . The stent of  claim 1 , wherein the average pore size of the inner layer of electrospun PTFE fibers is between 1 micron and 12 microns. 
     
     
         3 . The stent of  claim 1 , wherein the outer layer of electrospun PTFE fibers has an average pore size configured to resist tissue growth. 
     
     
         4 . The stent of  claim 3 , wherein the average pore size of the outer layer of electrospun PTFE fibers is 1.5 microns or less. 
     
     
         5 . The stent of  claim 1 , further comprising a cuff adjacent an end of the stent, the cuff configured to promote rapid cellular ingrowth into the cuff. 
     
     
         6 . The stent of  claim 1 , wherein the non-electrospun tie layer comprises fluorinated ethylene propylene (FEP). 
     
     
         7 . The stent of  claim 1 , further comprising a scaffolding structure configured to resist radial compression when disposed in a lumen of a patient. 
     
     
         8 . The stent of  claim 7 , wherein the scaffolding structure is comprised of a single wire. 
     
     
         9 . The stent of  claim 8 , wherein the wire is helically wound around a central axis of the stent. 
     
     
         10 . The stent of  claim 8 , wherein the wire has a wave like pattern defining apexes and arms. 
     
     
         11 . The stent of  claim 8 , wherein the scaffolding structure comprises two longitudinal portions of different compressibilities. 
     
     
         12 . A method of constructing a stent, comprising;
 electrospinning a first tube of PTFE onto a rotating mandrel;   sintering the first tube;   applying a tie layer around the first tube, and   applying a second tube of electrospun PTFE around the tie layer,   wherein the first tube of PTFE has an average pore size configured to permit growth of endothelial cells on a surface of the stent and the tie layer is impermeable to tissue growth.   
     
     
         13 . The method of  claim 12 , wherein electrospinning the first and second tubes of PTFE comprises:
 mixing a PTFE dispersion with PEO, wherein the PEO is dissolved in water to form a mixture; and   discharging the mixture from an orifice onto the rotating mandrel.   
     
     
         14 . The method of  claim 12 , wherein the average pore size of the first tube is between 1 micron and 12 microns. 
     
     
         15 . The method of  claim 12 , wherein the second tube has an average pore size configured to resist tissue growth. 
     
     
         16 . The method of  claim 15 , wherein the average pore size of the second tube is 1.5 microns or less. 
     
     
         17 . The method of  claim 12 , further comprising heat treating the stent such that the tie layer bonds to the first and second tubes. 
     
     
         18 . The method of  claim 17 , wherein the tie layer partially coats fibers of the first and second tubes. 
     
     
         19 . The method of  claim 17 , further comprising applying a compressive wrap around the second tube before the stent is heat treated.