Methods of forming a coating for a prosthesis

Abstract

Methods of forming a coating onto an implantable device or endoluminal prosthesis, such as a stent, are provided. The coating may be used for the delivery of an active ingredient. The coating may have a selected pattern of interstices for allowing a fluid to seep through the coating in the direction of the pattern created.

What is claimed is:  
     
         1 . A method of forming a coating for a prosthesis, comprising: 
 depositing a polymeric sheath over at least a portion of a prosthesis, said prosthesis having a plurality of interconnected struts separated by gaps and a longitudinally extending central bore for allowing a fluid to travel through said prosthesis; and    exposing said polymeric sheath to a temperature not greater than about the melting temperature of the polymer to form a coating for said prosthesis.    
     
     
         2 . A coated stent produced in accordance with the method of  claim 1 .  
     
     
         3 . The method of  claim 1 , wherein said coating covers said gaps underlying said sheath.  
     
     
         4 . The method of  claim 1 , wherein said method further comprises: 
 removing a portion of said coating positioned over some of said gaps to form a pattern of interstices dispersed between said struts for allowing a fluid that flows through said central bore to seep through said coating.    
     
     
         5 . The method of  claim 4 , wherein said removing is performed by applying a laser discharge to said portion of said coating to form a preselected pattern of interstices.  
     
     
         6 . The method of  claim 1 , wherein said temperature is above the glass transition temperature for the polymer.  
     
     
         7 . The method of  claim 1 , wherein said coating is made from an ethylene vinyl alcohol copolymer.  
     
     
         8 . The method of  claim 1 , wherein said coating is impregnated with an active ingredient for the sustained release of said active ingredient when said prosthesis is implanted in a biological passageway, and wherein said active ingredient is selected from a group of antiproliferative, antineoplastic, antiinflammatory, antiplatelet, anticoagulant, antifibrin, antithrombin, antimitotic, antibiotic, antioxidant substances and combinations thereof.  
     
     
         9 . The method of  claim 8 , wherein said method further comprises: 
 forming a rate limiting membrane over said coating.    
     
     
         10 . The method of  claim 1 , wherein said coating contains actinomycin D, docetaxel, or paclitaxel.  
     
     
         11 . The method of  claim 1 , wherein said coating contains a material selected from a group of radioactive isotopes and radiopaque elements.  
     
     
         12 . The method of  claim 1 , wherein said method further comprises: 
 forming a second coating onto said coating on said prosthesis, wherein said second coating is impregnated with an active ingredient for the sustained release of said active ingredient when said prosthesis is implanted in a biological passageway.    
     
     
         13 . A method for increasing an amount of a polymeric coating on a stent having struts separated by gaps, without increasing the thickness of the coating, comprising the acts of: 
 inserting a stent having a plurality of interconnected struts separated by gaps into a polymeric sheath; and    exposing said polymeric sheath to a temperature not greater than about the melting temperature of the polymer to form a coating for said stent, wherein said coating covers said struts and said gaps between said struts so as to increase the quantity of said polymeric coating supported by said stent without increasing the thickness of said coating on said stent.    
     
     
         14 . The method of  claim 13 , further comprising: 
 removing a portion of said coating deposited over at least one of said gaps to create an opening in said coating, wherein the size of said opening is smaller than the size of said gap, and wherein said opening allows a fluid to travel through said coating from within said stent.    
     
     
         15 . The method of  claim 14 , wherein said act of removing comprises: 
 applying a laser discharge to a portion of said coating deposited over at least one of said gaps to create said opening in said coating.    
     
     
         16 . The method of  claim 13 , wherein said polymeric coating comprises an active ingredient to inhibit restenosis.  
     
     
         17 . The method of  claim 13 , wherein said temperature is not less than about the glass transition temperature of the polymer.