Vascular stent having increased radiopacity and method for making same

Abstract

A stent for use in a patient's blood vessel to maintain the patency of the vessel contains strategically located radiopaque material. The strategic placement of the radiopaque material in the core structure of the stent functions to enhance the resolution of the stent under fluoroscopy. The initial part of the process includes forming a groove in a piece of tube stock and securing radiopaque material into the groove by press fitting or diffusion bonding. After the securing method, a layer of material can be sputtered coated over the only radiopaque material or over the entire stent. Finally, a pattern of struts and splines is cut into the tube composite to form the stent.

What is claimed:  
     
         1 . A method for forming a vascular stent having increased radiopacity, comprising the steps of: 
 selecting a tube of structural material;    forming at least one groove along the tube;    inserting radiopaque material into the groove;    securing said radiopaque material to the tube;    cutting the tube into a particular pattern to form spines and struts of a stent.    
     
     
         2 . The method of  claim 1 , wherein: 
 the tube of structural material is formed of a biocompatible material selected from the group consisting of stainless steel, nickel-titanium alloys, and cobalt-based alloys.    
     
     
         3 . The method of  claim 1 , wherein: 
 the step of forming the groove comprises forming one continuous groove.    
     
     
         4 . The method of  claim 1 , wherein: 
 the radiopaque material is formed in a strip and the step of inserting the radiopaque material comprises inserting the strip into the groove.    
     
     
         5 . The method of  claim 1 , wherein: 
 the method of  claim 1 , wherein the step of securing the radiopaque material includes the step of laser binding the radiopaque material into the groove.    
     
     
         6 . The method of  claim 4 , wherein: 
 the step of securing the strip includes press-fitting the strip into the groove.    
     
     
         7 . The method of  claim 4 , wherein: 
 the step of securing the strip includes the step of diffusion bonding the strip into the groove.    
     
     
         8 . The method of  claim 4 , wherein: 
 the step of forming the groove comprises forming a plurality of grooves.    
     
     
         9 . The method of  claim 8 , wherein: 
 a plurality of strips of radiopaque material are inserted into the plurality of grooves.    
     
     
         10 . The method of  claim 1 , wherein: 
 the step of securing the radiopaque material into the groove includes press-fitting the material into the groove.    
     
     
         11 . The method of  claim 1 , wherein: 
 the step of securing the radiopaque material includes the step of diffusion bonding the material into the groove.    
     
     
         12 . The method of  claim 1  wherein: 
 the grooves are formed as a plurality of rings.  
 
     
     
         13 . The method of  claim 1 , wherein: 
 the cutting step is performed by a laser.    
     
     
         14 . The method of  claim 1 , wherein: 
 the step of forming the grooves includes forming them on the exterior of the tube.    
     
     
         15 . The method of  claim 1 , further including the step of: 
 sputter coating a layer of metal over the exterior surface of the radiopaque material.    
     
     
         16 . The method of  claim 1 , wherein: 
 the step of forming the grooves includes forming them on the exterior of the tube in a selected pattern.    
     
     
         17 . The method of  claim 16 , wherein: 
 the step of cutting the tube is performed in a pattern which selectively places radiopaque material on particular struts or spines of the finished stent.    
     
     
         18 . A stent having enhanced radiopacity, comprising: 
 a tubular section constructed of at least one segment of a tube;    the segment having at least one groove formed therein;    a radiopaque material disposed within the groove; and    means for securing the material within the groove.    
     
     
         19 . The stent of  claim 18 , wherein: 
 the means for securing the radiopaque material in the groove includes sputter coating a layer of metal over the radiopaque material.    
     
     
         20 . The stent of  claim 18 , wherein: 
 the segment includes a target area; and    the groove is formed in selective patterns in the target area.    
     
     
         21 . The stent of  claim 18 , wherein: 
 the segment is formed with one groove along a longitudinal line and the radiopaque material is located in the groove.    
     
     
         22 . The stent of  claim 18  wherein: 
 the means for securing the radiopaque material within the groove includes press fitting the material into the groove.  
 
     
     
         23 . The stent of  claim 18 , wherein: 
 the means for securing the radiopaque material within the groove includes diffusion bonding the material into the groove.    
     
     
         24 . The stent of  claim 18 , wherein: 
 the segment is formed with a plurality of grooves and the radiopaque material is formed in strips which are placed within the grooves.    
     
     
         25 . The stent of  claim 18  wherein: 
 the means for securing the radiopaque material within the grooves includes press fitting the strips of radiopaque material into the grooves.  
 
     
     
         26 . The stent of  claim 18 , wherein: 
 the means for securing the radiopaque material within the grooves includes diffusion bonding the strips of radiopaque material into the grooves.    
     
     
         27 . The stent of  claim 18 , wherein: 
 the means for securing the radiopaque material in the grooves includes sputter coating a layer of metal over the strips of radiopaque material.