Reinforced catheter and method of manufacture

Abstract

A catheter shaft is disclosed that may reduce the thickness of the inner layer and/or may allow the reinforcing layer to share the same space as the inner lubricious layer. In one illustrative embodiment, the inner lubricious layer is removed altogether, and an inner tubular braid member defines the inner lumen of the catheter shaft. In another illustrative embodiment, the inner lubricious layer and the reinforcing layer are effectively combined to form a reinforcing member. To combine the inner lubricious layer and the reinforcing layer, the wires used to form the reinforcing braid or coil are first coated with a lubricious polymer such as PTFE or PFA. When these strands are wound to form the tubular reinforcing member, the inner surface of the reinforcing member includes a lubricious surface. Various methods are also disclosed for providing a smooth inner surface for the catheter shaft.

What is claimed is:  
     
         1 . A catheter shaft having an inner lumen extending therethrough, comprising: 
 an inner tubular braid member formed from one or more braided strands, the inner tubular braid member defining at least part of the inner lumen of the catheter shaft; and    an outer tubular member disposed over the inner tubular braid member.    
     
     
         2 . A catheter according to  claim 1 , wherein selected strands include an elongated inner core coated with a polymer.  
     
     
         3 . A catheter according to  claim 2 , wherein the inner core is formed from stainless steel.  
     
     
         4 . A catheter according to  claim 2 , wherein the polymer is a lubricious polymer.  
     
     
         5 . A catheter according to  claim 4 , wherein the polymer includes polytetrafluoroethylene (PTFE).  
     
     
         6 . A catheter according to  claim 4 , wherein the polymer is a perfluoroalkoxy polymer.  
     
     
         7 . A catheter according to  claim 1 , wherein the outer tubular member includes polyester.  
     
     
         8 . A catheter according to  claim 7 , wherein the outer tubular member is extruded over the inner tubular braid member.  
     
     
         9 . A method for forming a catheter shaft, the method comprising the steps of: 
 winding one or more elongated strands around a mandrel, wherein selected strands have an inner core coated by a polymer, the wound elongated strands collectively forming an inner tubular reinforcing member;    providing an outer tubular member over the inner tubular reinforcing member; and    removing the mandrel.    
     
     
         10 . A method according to  claim 9 , wherein the one or more elongated strands are wound to form a braid.  
     
     
         11 . A method according to  claim 9 , wherein the providing step includes the step of extruding a polymer over the inner tubular reinforcing member to form the outer tubular member.  
     
     
         12 . A method according to  claim 10 , wherein the braid is wound in a pattern that substantially prevents the extruded polymer of the outer tubular member from flowing through the inner tubular reinforcing member to the mandrel.  
     
     
         13 . A method according to  claim 9 , wherein the one or more elongated strands are wound to form a coil.  
     
     
         14 . A method according to  claim 9 , wherein the inner core of selected strands is stainless steel.  
     
     
         15 . A method according to  claim 9 , wherein the polymer encasing the inner core of selected strands is a lubricious polymer.  
     
     
         16 . A method according to  claim 15 , wherein the lubricious polymer is polytetrafluoroethylene (PTFE).  
     
     
         17 . A method according to  claim 16 , wherein the mandrel comprises a copper core coated with silver.  
     
     
         18 . A method according to  claim 16 , further comprising the step of applying heat and pressure to the inner tubular reinforcing member before providing the outer tubular member.  
     
     
         19 . A method according to  claim 18 , wherein the applied heat and pressure is sufficient to cause the polytetrafluoroethylene (PTFE) polymer that coats the inner core of selected strands to substantially conform to the shape of the mandrel.  
     
     
         20 . A method according to  claim 15 , wherein the lubricious polymer is a perfluoroalkoxy polymer.  
     
     
         21 . A method according to  claim 20 , wherein the mandrel is formed from an acetyl polymer.  
     
     
         22 . A method according to  claim 20 , further comprising the step of applying heat to the inner tubular reinforcing member before providing the outer tubular member.  
     
     
         23 . A method according to  claim 22 , wherein the applied heat is sufficient to cause the perfluoroalkoxy polymer that coats the inner core of selected strands to flow and create a thin-walled liner adjacent the mandrel.  
     
     
         24 . A method according to  claim 22 , wherein the heat is provided by a heated die.  
     
     
         25 . A method according to  claim 22 , wherein the providing step includes the step of extruding a polymer over the inner tubular reinforcing member to form the outer tubular member.  
     
     
         26 . A method according to  claim 25 , wherein the heat is applied by the extrusion of the outer tubular member.  
     
     
         27 . A method according to  claim 9 , further comprising the step of etching an outer surface of the inner tubular reinforcing member before providing the outer layer.  
     
     
         28 . A method for forming a catheter shaft, the method comprising the steps of: 
 winding one or more elongated strands around a mandrel having a relatively smooth outer surface, wherein selected strands have an inner core coated by a polymer, the wound elongated strands collectively forming an inner tubular reinforcing member;    applying heat to the inner tubular reinforcing member, wherein the heat is sufficient to cause the polymer that coats the inner core of selected strands to conform to the relatively smooth outer surface of the mandrel; and    removing the mandrel.    
     
     
         29 . A method according to  claim 28 , wherein the heat applying step further includes the step of applying inward pressure to the inner tubular reinforcing member toward the mandrel.  
     
     
         30 . A method according to  claim 28 , further comprising the step of providing an outer tubular member over the inner tubular reinforcing member.  
     
     
         31 . A method according to  claim 30 , further comprising the step of etching the outer surface of the inner tubular reinforcing member before providing the outer tubular member.  
     
     
         32 . A method according to  claim 30 , wherein the outer tubular member is provided by extruding a polymer over the inner tubular reinforcing member.  
     
     
         33 . A method according to  claim 32 , wherein the extruding step provides the heat for the heat applying step.