Implantable nickel-free stainless steel stents and method of making the same

Abstract

The present invention is directed to a stainless steel stent which is substantially nickel-free and possesses improved elongation and mechanical properties, including resistance to corrosion. The stent can be embodied in a substrate with one or more metallic claddings overlaying the substrate. The substrate and claddings can include radiopaque materials and stainless steel.

What is claimed:  
     
         1 . A stent for implantation in a body lumen of a patient, comprising: 
 a pattern of struts interconnected to form a structure that contacts a body lumen wall to maintain the patency of the body lumen, wherein the struts are made from stainless steel that is virtually free of any trace of nickel.    
     
     
         2 . The stent of  claim 1 , wherein the structure has a substrate and a first metallic cladding.  
     
     
         3 . The stent of  claim 2 , wherein the substrate is made from stainless steel that is virtually free of any trace of nickel and the first metallic cladding is selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials.  
     
     
         4 . The stent of  claim 2 , wherein the structure has a second metallic cladding.  
     
     
         5 . The stent of  claim 4 , wherein the second metallic cladding includes a metal selected from the group of metals including stainless steel.  
     
     
         6 . The stent of  claim 1 , wherein the amount of nickel in the structure is less than or equal to 0.3 percent by weight.  
     
     
         7 . A stent for implantation in a body lumen of a patient, comprising: 
 a pattern of struts interconnected to form a structure that contacts a body lumen wall to maintain the patency of the body lumen, wherein the structure includes a substrate made from nickel-titanium alloy, a first metallic cladding made from a stainless steel that is virtually free of any trace of nickel, and a second metallic cladding made from a radiopaque material.    
     
     
         8 . The stent of  claim 7 , wherein the amount of nickel in the structure is less than or equal to 0.3 percent by weight.  
     
     
         9 . The stent of  claim 7 , wherein the structure is constructed from BioDur® 108 Alloy.  
     
     
         10 . The stent of  claim 7 , wherein the second metallic cladding is selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials.  
     
     
         11 . A method of fabricating a stent for implantation within a body lumen, comprising the steps of: 
 providing a substrate tube having an outside surface and an inside surface, wherein the substrate tube is formed from stainless steel that is virtually free of any trace of nickel;    disposing a first cladding tube overlaying the substrate tube, wherein the first cladding tube includes a radiopaque material selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials;    joining the first cladding tube to the outside surface of the substrate tube to form a laminated tube; and    forming stent struts in the laminated tube.    
     
     
         12 . The method of  claim 11 , further comprising the steps of: 
 providing a second cladding tube including a metal selected from the group of metals including stainless steel;    disposing the second cladding tube overlaying the first cladding tube; and    joining the second cladding tube to the first cladding tube.    
     
     
         13 . The method of  claim 11 , wherein the step of joining the first cladding tube further includes deep drawing the laminated tube.  
     
     
         14 . The method of  claim 11 , wherein the step of joining the first cladding tube further includes rolling and drawing the laminated tube to mechanically interlock and to generate heat to fuse the first cladding tube to the substrate tube.  
     
     
         15 . The method of  claim 11 , wherein the step of joining the first cladding tube further includes passing the substrate tube through a series of dies to reduce the outside surface of the substrate tube by about 25 percent.  
     
     
         16 . The method of  claim 11 , wherein the step of disposing the first cladding tube further includes providing an outside diameter of the first cladding tube that has an interference fit with the outside surface of the substrate tube.  
     
     
         17 . The method of  claim 11 , wherein the step of forming stent struts further includes chemically etching the laminated tube.  
     
     
         18 . The method of  claim 11 , wherein the step of forming stent struts further includes laser cutting the laminated tube.  
     
     
         19 . The method of  claim 11 , further comprising the step of cold working the laminated tube.  
     
     
         20 . The method of  claim 11 , wherein the first cladding tube has a wall thickness that is less than a wall thickness of the substrate tube.  
     
     
         21 . A method of fabricating a stent for implantation within a body lumen, comprising the steps of: 
 providing a substrate tube having an outside diameter, wherein the substrate tube is formed from stainless steel that is virtually free of any trace of nickel;    providing a first cladding tube having an inside diameter, wherein the inside diameter has an interference fit with the outside diameter of the substrate tube, and wherein the first cladding tube includes a radiopaque material selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials;    disposing the first cladding tube overlaying the substrate tube;    joining the first cladding tube to the substrate tube to form a laminated tube; and    forming a pattern of stent struts in the laminated tube to obtain the stent.    
     
     
         22 . The method of  claim 21 , wherein the step of joining the first cladding tube further includes deep drawing the laminated tube.  
     
     
         23 . The method of  claim 21 , further comprising the steps of: 
 providing a second cladding tube including a metal selected from the group of metals including stainless steel, wherein the second cladding tube includes an inside diameter having an interference fit with an outside diameter of the first cladding tube;    disposing the second cladding tube overlaying the first cladding tube; and    joining the first cladding tube, the second cladding tube, and the substrate tube to form a laminated tube.    
     
     
         24 . The method of  claim 21 , wherein the step of joining the first cladding tube further includes deep drawing the laminated tube.  
     
     
         25 . The method of  claim 24 , wherein the step of deep drawing further includes passing the laminated tube through a series of dies.  
     
     
         26 . The method of  claim 21 , wherein the method further comprises annealing the laminated tube.  
     
     
         27 . A stent for implantation within a body lumen, comprising: 
 a substrate tube having an exterior, wherein the substrate tube is formed from stainless steel that is virtually free of any trace of nickel;    a metallic cladding mechanically interlocked under pressure over the xterior of the substrate tube; and    a pattern of stent struts formed in the substrate and metallic cladding.    
     
     
         28 . The stent of  claim 27 , wherein the cladding includes a radiopaque material selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials.  
     
     
         29 . The stent of  claim 27 , wherein a wall thickness of the cladding is less than a wall thickness of the substrate tube.  
     
     
         30 . The stent of  claim 27 , wherein the stent includes a second layer of metallic cladding mechanically interlocked under pressure to an exterior of the cladding over the substrate tube.  
     
     
         31 . A stent for implantation within a body lumen, comprising: 
 a substrate tube having an exterior, wherein the substrate tube is formed from stainless steel that is virtually free of any trace of nickel;    a metallic cladding mechanically interlocked under pressure over the exterior of the substrate tube; and    a pattern of stent struts formed in the substrate and metallic cladding.    
     
     
         32 . The stent of  claim 31 , wherein the metallic cladding is formed from a stainless steel selected from the group of stainless steels including Type 316L stainless steel.  
     
     
         33 . A stent for implantation within a body lumen, comprising: 
 a substrate tube having an exterior, wherein the substrate tube is formed from stainless steel that is virtually free of any trace of nickel;    a first cladding mechanically interlocked under pressure over the exterior of the substrate tube, wherein the first cladding is formed from a radiopaque material;    a second cladding mechanically interlocked under pressure over the exterior of the first cladding, wherein the second cladding is formed stainless steel that is virtually free of any trace of nickel; and    a pattern of stent struts formed in the substrate and metallic cladding.    
     
     
         34 . A method of fabricating a stent for implantation within a body lumen, comprising the steps of: 
 providing a substrate sheet having an outside surface and an inside surface, wherein the substrate sheet is formed from stainless steel that is virtually free of any trace of nickel;    disposing a first cladding sheet overlaying the substrate sheet, wherein the first cladding sheet includes a radiopaque material selected from the group of radiopaque materials including platinum-10% iridium, platinum, gold, palladium, tantalum, tungsten, and other radiopaque materials;    joining the first cladding sheet to the outside surface of the substrate sheet to form a laminated sheet;    rolling the laminated sheet into a laminated tube;    welding the laminated tube; and    forming stent struts in the laminated tube.    
     
     
         35 . The method of  claim 34 , further comprising the steps of: 
 providing a second cladding sheet including a metal selected from the group of metals including stainless steel;    disposing the second cladding sheet overlaying the first cladding sheet; and    joining the second cladding sheet to the first cladding sheet.    
     
     
         36 . The method of  claim 34 , wherein the step of joining the first cladding sheet further includes deep drawing the laminated sheet.  
     
     
         37 . The method of  claim 34 , wherein the step of forming stent struts further includes chemically etching the laminated tube.  
     
     
         38 . The method of  claim 34 , wherein the step of forming stent struts further includes laser cutting the laminated tube.  
     
     
         39 . The method of  claim 34 , wherein the method further comprises the step of cold working the laminated tube.  
     
     
         40 . The method of  claim 34 , wherein the method further comprises the steps of: 
 disposing a second cladding sheet overlaying the laminated sheet, wherein the second cladding sheet includes a metal selected from the group of metals including stainless steel; and    joining the second cladding sheet to the laminated sheet.    
     
     
         41 . The method of  claim 34 , wherein the first cladding tube has a wall thickness that is less than a wall thickness of the substrate tube.