Method of making a medical device having a thin wall tubular membrane over a structural frame

Abstract

The present invention relates to a medical device and method for making the medical device. In particular, the present invention relates to membrane covered structural frame, and to a method of forming a tubular membrane on a structural frame. In one aspect, a polymeric tube is provided having a first diameter and a first tube wall thickness. A radially expandable and contractible structural frame is radially contracted, and inserted into at least a portion of the structural frame. The radially contracted structural frame then expands to expand the polymeric tube to a second diameter, wherein the second diameter is greater than the first diameter. As the polymeric tube radially expands, the tube wall thickness becomes thinner, so that the polymeric tube becomes a thin walled tubular membrane. The polymeric tube and structural frame are then mechanically attached to each other.

What is claimed is:  
     
         1 . A method of making a medical device having a thin wall tubular structure over a radially contractible and expandable structural frame, the method comprising the steps of: 
 providing a polymeric tube having a first diameter and a first wall thickness;    radially contracting the structural frame;    placing the radially contracted structural frame at least partially into the polymeric tube;    expanding the structural frame to expand at least a portion of the polymeric tube to a second diameter having a second wall thickness, the second diameter of the polymeric tube being greater than the first diameter, the second wall thickness being smaller than the first wall thickness; and    mechanically attaching the expanded polymeric tube to the expanded structural frame.    
     
     
         2 . The method of  claim 1  wherein the step of radially contracting the structural frame comprises inserting the structural frame into a sheath, the sheath being sized to have an inside diameter that is smaller than the outside diameter of the structural frame.  
     
     
         3 . The method of  claim 1  wherein the step of radially contracting the structural frame comprises: 
 radially crimping the structural frame with a crimping device to a reduced diameter; and  
 cooling the radially crimped structural frame to temporarily maintain the radially contracted configuration.  
 
     
     
         4 . The method of  claim 1  wherein the step of radially expanding the structural frame comprises: 
 inserting a radial expansion device into the structural frame along the structural frame's longitudinal axis;  
 radially expanding the radial expansion device to expand the structural frame.  
 
     
     
         5 . The method of  claim 4  wherein the radial expansion device is an inflation balloon.  
     
     
         6 . The method of  claim 4  wherein the radial expansion device is a radially expanding cage assembly.  
     
     
         7 . The method of  claim 4  wherein the radial expansion device is a radially expanding mandrel.  
     
     
         8 . The method of  claim 4  wherein the radial expansion device is a tapered mandrel.  
     
     
         9 . The method of  claim 1  wherein the step of radially expanding the structural frame comprises removing a sheath constraining the radially contracted structural frame, thereby allowing the structural frame to radially expand.  
     
     
         10 . The method of  claim 1  wherein the step of radially expanding the structural frame comprises heating the radially contracted structural frame.  
     
     
         11 . The medical device of  claim 1  wherein the step of mechanically attaching the expanded polymeric tube to the expanded structural frame comprises suturing the polymeric tube to the structural frame.  
     
     
         12 . The medical device of  claim 1  wherein the step of mechanically attaching the expanded polymeric tube to the expanded structural frame comprises welding the polymeric tube to the structural frame.  
     
     
         13 . The medical device of  claim 1  wherein the step of mechanically attaching the expanded polymeric tube to the expanded structural frame comprises adhering the polymeric tube to the structural frame with an adhesive.  
     
     
         14 . The medical device of  claim 1  wherein the step of mechanically attaching the expanded polymeric tube to the expanded structural frame comprises coating at least a porting of the expanded polymeric tube and the structural frame with a polymer.  
     
     
         15 . The method of  claim 14  wherein the step of coating comprises spraying a polymer solution over at least a portion of the expanded polymeric tube and structural frame.  
     
     
         16 . The method of  claim 14  wherein the step of coating comprises dipping at least a portion of the expanded polymeric tube and structural frame in a polymer solution.  
     
     
         17 . The method of  claim 14  wherein the step of coating comprises: 
 dipping at least a portion of the expanded polymeric tube and structural frame in a polymer solution; and  
 spinning the dip coated expanded polymeric tube and structural frame to evenly distribute the coating.  
 
     
     
         18 . A method of placing a tubular structure about a radially contractible and expandable structural frame, the method comprising the steps of: 
 providing a porous polymeric tube having a first diameter and a first wall thickness;    radially contracting the structural frame;    placing the radially contracted structural frame at least partially into the porous polymeric tube;    expanding the structural frame to expand at least a part of the porous polymeric tube to a second diameter, the second diameter of the porous polymeric tube being greater than the first diameter; and    coating at least a portion of the expanded porous polymeric tube and the expanded structural frame, thereby mechanically attaching the expanded porous polymeric tube to the expanded structural frame.    
     
     
         19 . The method of  claim 18  wherein the step of mechanically attaching the expanded porous polymeric tube to the expanded structural frame comprises: 
 filling the at least a portion of the pores in the coated porous polymeric tube with a polymer solution; and  
 curing the polymer solution, thereby mechanically bonding the porous polymeric tube to the coated structural frame.  
 
     
     
         20 . The method of  claim 1  further comprising performing post processing of the expanded polymeric tube.  
     
     
         21 . The method of  claim 20  wherein the step of post processing includes reshaping the expanded polymeric tube.  
     
     
         22 . The method of  claim 20  wherein the step of post processing includes thinning at least a portion of the expanded polymeric tube.  
     
     
         23 . The method of  claim 20  wherein the step of post processing includes thickening at least a portion of the expanded polymeric tube.  
     
     
         24 . The method of  claim 20  wherein the step of post processing includes forming cusps in the expanded polymeric tube.  
     
     
         25 . A medical device having a tubular membrane structure comprising: 
 a radially expandable and collapsible structural frame;    a thin wall membrane positioned over the radially expandable and collapsible structural frame, the membrane formed at least in part by radially expanding a polymeric tube with the structural frame; and    a coating over the thin wall membrane, the coating and thin wall membrane forming the tubular membrane structure, and wherein the coating mechanically attaches the thin wall membrane to the structural frame.    
     
     
         26 . The medical device of  claim 25  wherein the structural frame comprises a lattice of interconnected elements, and having a substantially cylindrical configurations with first and second open ends and a longitudinal axis extending there between.  
     
     
         27 . The medical device of  claim 25  wherein the thin wall membrane comprises ePTFE.  
     
     
         28 . The medical device of  claim 25  wherein the polymeric tube has a wall thickness before radial expansion in the range from about 25 μm to about 50 μm.  
     
     
         29 . The medical device of  claim 25  wherein the thin wall membrane has a wall thickness after radial expansion in the range from about 12 μm to about 25 μm.  
     
     
         30 . The medical device of  claim 25  wherein the coating comprises a polymer.  
     
     
         31 . The medical device of  claim 30  wherein the polymer coating comprises an elastomeric polymer.  
     
     
         32 . The medical device of  claim 31  wherein the elastomeric polymer comprises an elastomeric fluoropolymer.  
     
     
         33 . The medical device of  claim 32  wherein the elastomeric fluoropolymer comprises a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene.  
     
     
         34 . The medical device of  claim 31  wherein the elastomeric polymer comprises siliconized polyurethane.  
     
     
         35 . The medical device of  claim 34  wherein the siliconized polyurethane comprises segmented polyetherurethane.  
     
     
         36 . The medical device of  claim 25  wherein the coating has a wall thickness from about 12 μm to about 25 μm.  
     
     
         37 . The medical device of  claim 25  wherein the thin wall membrane comprises a therapeutic agent.  
     
     
         38 . The medical device of  claim 25  wherein the thin wall membrane comprises a pharmaceutic agent.  
     
     
         39 . The medical device of  claim 25  wherein the coating comprises a therapeutic agent.  
     
     
         40 . The medical device of  claim 25  wherein the coating comprises a pharmaceutic agent.  
     
     
         41 . The medical device of  claim 25  wherein at least a porting of the structural frame is coated with a therapeutic agent.  
     
     
         42 . The medical device of  claim 25  wherein at least a portion of the structural frame is coated with a pharmaceutic agent.