Polymeric marker with high radiopacity for use in medical devices

Abstract

High radiopacity is achieved in a polymeric marker by combining a polymeric resin, a powdered radiopaque agent having uniformly shaped particles of a specific particle size distribution and a wetting agent. The method to produce the marker calls for the blending and pelletization of these materials followed by extrusion onto support beading. The resulting supported tubing is subsequently cut to length with the beading still in place. After ejection of the beading remnant the marker is slipped into place on the device to be marked and attached by melt bonding. Marking of a guidewire allows lesions to be measured while the marking of balloon catheters allow the balloon to be properly positioned relative to a lesion.

1 - 17 . (canceled) 
     
     
         18 . A method of radiopaquely marking a medical device, comprising:
 providing a flexible polymeric radiopaque marker containing greater than 30 volume percent radiopaque particles, wherein such particles have an average diameter of at least 2 microns and a maximum diameter of about 20 microns;   accurately positioning said marker on said medical device; and   melt bonding said marker in place.   
     
     
         19 . The method of  claim 18 , further comprising disposing a length of heat shrink tubing about said accurately positioned marker and heating said tubing. 
     
     
         20 . The method of  claim 18 , wherein said radiopaque particles comprise tungsten. 
     
     
         21 . The method of  claim 18 , wherein said medical device comprises a balloon catheter and said marker is positioned on an inner member disposed within an expandable balloon. 
     
     
         22 . The method of  claim 18 , wherein said medical device comprises a guidewire. 
     
     
         23 . The method of  claim 22 , wherein a plurality of said markers are bonded to said guidewire. 
     
     
         24 . The method of  claim 23 , wherein said markers are equally spaced relative to one another so as to function as a ruler under fluoroscopic inspection. 
     
     
         25 . The method of  claim 23 , wherein said guidewire includes a radiopaque feature and wherein said markers are each spaced a preselected distance from said feature. 
     
     
         26 . The method of  claim 23 , wherein said markers each have a different length so as to function as gauges under fluoroscopic inspection. 
     
     
         27 . A device for measuring lesion sizes, comprising:
 a guidewire; and   at least one flexible polymeric radiopaque marker is melt bonded to a distal end of said guidewire, wherein said marker contains radiopaque particles comprising at least 30 percent of its volume.   
     
     
         28 . The device of  claim 27 , wherein two or more of said markers are melt bonded to said guidewire at preselected spacing relative to one another so as to function as a ruler under fluoroscopic inspection. 
     
     
         29 . The device of  claim 27 , wherein said guidewire includes a radiopaque feature and said marker is melt bonded a preselected distance therefrom. 
     
     
         30 . The device of  claim 27 , wherein said marker has a preselected length so as to function as a gauge under fluoroscopic inspection. 
     
     
         31 . The device of  claim 27 , wherein a plurality of said markers are bonded to said guidewire, each of a different length so as to function as gauges under fluoroscopic inspection. 
     
     
         32 . The device of  claim 27 , wherein said radiopaque particles comprise tungsten. 
     
     
         33 . The device of  claim 32 , wherein a wetting agent facilitates encapsulation of said radiopaque particles by polyether block amide. 
     
     
         34 . The device of  claim 33 , wherein said wetting agent comprises maleic anhydride. 
     
     
         35 . A radiopaque, elastomeric composition, comprising:
 a polymer;   radiopaque particles disposed within said polymer having an average diameter of at least 2 microns and a maximum diameter of about 20 microns; and   a wetting agent for facilitating encapsulation of said particles by said polymer.   
     
     
         36 . The composition of  claim 35 , wherein said radiopaque particles comprise greater than 18 volume percent of said marker. 
     
     
         37 . The composition of  claim 36 , wherein said radiopaque particles comprise approximately 36 volume percent of said marker. 
     
     
         38 . The composition of  claim 35 , wherein said polymer comprises Pebax and said radiopaque particles comprise tungsten powder. 
     
     
         39 . The composition of  claim 38 , wherein said multi-functional polymeric additive comprises maleic anhydride graft polyolefin. 
     
     
         40 . The composition of  claim 35 , wherein said radiopaque particles are substantially equiaxed. 
     
     
         41 . The composition of  claim 40 , wherein said particles are produced by a pusher process. 
     
     
         42 . The composition of  claim 41 , wherein said particles are produced by an atomization process, resulting in a substantially spherical particle. 
     
     
         43 . The composition of  claim 35 , further comprising an antioxidant. 
     
     
         44 . The composition of  claim 35 , wherein said polymer is thermoplastic. 
     
     
         45 . The composition of  claim 35  formed so as to define a tubular structure. 
     
     
         46 . An intraluminal medical device, comprising an elongated shaft or core member having a radiopaque marker secured to a surface of the shaft or core member, and the radiopaque marker is formed of a compounded polymer mixture comprising:
 a polymer;   radiopaque particles having an average diameter of at least about 2 microns and a maximum diameter of about 20 microns, the radiopaque particles comprising at least 30 volume percent of the marker; and   a wetting agent for facilitating encapsulation of said particles by said polymer.   
     
     
         47 - 53 . (canceled)