Methods of making a prosthesis with a smooth covering

Abstract

The present invention relates to methods of making a prosthesis or a stent with a smooth covering. The method includes providing an elastomeric tube including an inner diameter and an outer diameter, positioning the elastomeric tube in a tube expander including a vacuum, expanding the inner diameter and the outer diameters of the elastomeric tube by applying the vacuum, providing a mandrel, positioning an inner covering over the mandrel, positioning a stent over the inner covering, positioning an outer covering over the stent to form a covered stent, positioning the mandrel and the covered stent in the tube expander, releasing the vacuum, removing the elastomeric tube, the covered stent, and the mandrel form the tube expander, applying pressure and heat to the elastomeric tube, the covered stent, and the mandrel, removing the elastomeric tube, the covered stent, and the mandrel from the pressure and the heat, removing the elastomeric tube from the covered stent, and removing the mandrel from the covered stent.

1 - 20 . (canceled) 
     
     
         21 . An encapsulated stent graft comprising a substantially tubular body comprising:
 a luminal surface;   an abluminal surface;   a balloon expandable stent having an inner surface and an outer surface;   an inner cover covering the inner surface of the balloon expandable stent, the inner covering comprising:
 a first layer consisting essentially of a first material having a porous structure and a melting point and a second material, different from the first material and parallel to the first porous material, within the first layer and having a melting point lower than the melting point of the first porous material of the first layer, and 
 a second layer over the first layer consisting essentially of a first material having a porous structure and a melting point and a second material, different from the first material of the second layer, parallel to the first porous material within the second layer and having a melting point lower than the melting point of the first porous material of the second layer, 
 wherein the first material of the first layer is the luminal surface of the stent graft, the first material of the second layer contacts the first material of the first layer and the second material of the second layer, the second material of the second layer contacts the stent, and the second material of the first layer, upon the application of heat sufficient to melt the second material of the first layer, flows into the porous structure of the first material of the first layer and the porous structure of the first material of the second layer thereby forming a bond between the first material of the first layer and the first material of the second layer; and 
   an outer cover covering the outer surface of the balloon expandable stent, the outer cover comprising;
 a first layer consisting essentially of a first material having a porous structure and a melting point and a second material, different from the first material, parallel to the first material within the first layer and having a melting point lower than the melting point of the first material of the first layer, and, 
 a second layer over the first layer consisting essentially of a first material having a porous structure and melting point and a second material, different from the first material of the second layer, parallel to the first material within the second layer and having a melting point lower than the melting point of the first material of the second layer, 
 wherein the second material of the first layer contacts the stent and the first material of the first layer, the first material of the second layer is the abluminal surface of the stent graft, and second material of the second layer, upon the application of heat sufficient to melt the second material of the second layer, flows into the porous structure of the first material of the first layer and the porous structure of the first material of the second layer thereby forming a bond between the first material of the first layer and the first material of the second layer. 
   
     
     
         22 . The stent graft of  claim 21 , wherein the first material of the first layer and the second layer of the inner cover and the first material of the first layer and the second layer of the outer cover is selected from PTFE, esPTFE and ePTFE. 
     
     
         23 . The stent graft of  claim 22 , wherein the second material of the first layer and the second layer of the inner cover and the second material of the first layer and the second layer of the outer cover is selected from FEP and polyurethane. 
     
     
         24 . The stent graft of  claim 21 , wherein the first material of the first layer and the second layer of the inner cover is esPTFE and the second material of the first layer and the second layer of the outer cover is polyurethane. 
     
     
         25 . The stent graft of  claim 21 , wherein the first material of the first layer and the second layer of the inner cover is ePTFE and the second material of the first layer and the second layer of the outer cover is polyurethane. 
     
     
         26 . The stent graft of  claim 21 , wherein the first material of the first layer and the second layer of the inner cover is esPTFE and the second material of the first layer and the second layer of the outer cover is FEP. 
     
     
         27 . The stent graft of  claim 21 , wherein the first material of the first layer and the second layer of the inner cover is ePTFE and the second material of the first layer and the second layer of the outer cover is FEP. 
     
     
         28 . The stent graft of  claim 21 , wherein each of the inner cover and the outer cover each further include one or more additional layers consisting essentially of a first material having a porous structure and a melting point and a second material, different from the first material, parallel to the first material having a melting point greater than the melting point of the second material and wherein in each of the one or more additional layers the first and second materials are in an alternating pattern. 
     
     
         29 . An encapsulated stent graft comprising a substantially tubular body comprising:
 a luminal surface;   an abluminal surface;   a balloon expandable stent having an inner surface and an outer surface;   an inner cover covering the inner surface of the balloon expandable stent, the inner covering comprising:
 a first layer consisting essentially of a first material selected from PTFE, ePTFE and esPTFE, and a second material parallel to the first material selected from FEP and polyurethane and having a melting point lower than a melting point of the first material of the first layer, and 
 a second layer over the first layer consisting essentially of a first material that is the same as the first material of the first layer and a second layer parallel to the first material that is the same as the second material of the first layer and having a melting point lower than the melting point of the first material of the second layer, 
 wherein the first material of the first layer is the luminal surface of the stent graft, the first material of the second layer contacts the first material of the first layer and the second material of the second layer, the second material of the second layer contacts the stent, and the second material of the first layer, upon the application of heat sufficient to melt the second material of the first layer, is a bond between the first material of the first layer and the first material of the second layer; and 
   an outer cover covering the outer surface of the balloon expandable stent, the outer cover comprising;
 a first layer consisting essentially of a first material selected from PTFE, ePTFE and esPTFE, and a second material parallel to the first material selected from FEP and polyurethane and having a melting point lower than a melting point of the first material of the first layer, and 
 a second layer over the first layer consisting essentially of a first material that is the same as the first material of the first layer and a second layer parallel to the first material that is the same as the second material of the first layer and having a melting point lower than the melting point of the first material of the second layer, 
 wherein the second material of the first layer contacts the stent and the first material of the first layer, the first material of the second layer is the abluminal surface of the stent graft, and second material of the second layer, upon the application of heat sufficient to melt the second material of the second layer, is a bond between the first material of the first layer and the first material of the second layer; and 
   wherein the luminal and abluminal surfaces of the stent graft have no visible creases or ridges.   
     
     
         30 . The stent graft of  claim 29 , wherein each of the inner cover and the outer cover each further include one or more additional layers consisting essentially of a first material that is the same as the first material of the first and second layers and a second material that is the same as the second material of the first and second layers and each of the one or more additional layers the first and second materials are in an alternating pattern.