Expandable medical device with ductile hinges

Abstract

An expandable tissue supporting device of the present invention employs ductile hinges at selected points in the expandable device. When expansion forces are applied to the device as a whole, the ductile hinges concentrate expansion stresses and strains in small well defined areas. The expandable medical device including ductile hinges provides the advantages of low expansion force requirements, relatively thick walls which are radio-opaque, improved crimping properties, high crush strength, reduced elastic recoil after implantation, and control of strain to a desired level. The expandable tissue supporting device includes a plurality of elongated beams arranged in a cylindrical device and connected together by a plurality of ductile hinges. Although many ductile hinge configurations are possible, the ductile hinges preferably have a substantially constant hinge cross sectional area which is smaller than a beam cross sectional area such that as the device is expanded from a first diameter to a second diameter, the ductile hinges experience plastic deformation while the beams are not plastically deformed.

1 - 26 . (canceled) 
   
   
       27 . An expandable medical device comprising:
 at least one cylindrical tube;   a network of members formed in said cylindrical tube and allowing the cylindrical tube to be expanded or compressed from a first diameter to a second diameter; and   a plurality of openings in the members for loading of a beneficial agent therein, wherein the plurality of openings are formed in at least two different shapes.   
   
   
       28 . The expandable medical device according to  claim 27 , wherein the network of members are substantially rigid members interconnected by deformable members and wherein the substantially rigid members experience substantially no plastic deformation during expansion or compression from the first diameter to the second diameter. 
   
   
       29 . The expandable medical device according to  claim 28 , wherein the plurality of openings are formed in the substantially rigid members. 
   
   
       30 . The expandable medical device according to  claim 27 , wherein the plurality of openings extend through a thickness of said members, so as to thereby define a plurality of through-openings. 
   
   
       31 . The expandable medical device according to  claim 27 , wherein the plurality of openings have a depth less than a thickness of said members, so as to thereby define a recess. 
   
   
       32 . The expandable medical device according to  claim 27 , further comprising a beneficial agent loaded within the plurality of openings. 
   
   
       33 . The expandable medical device according to  claim 32 , wherein said beneficial agent includes antiproliferatives. 
   
   
       34 . The expandable medical device according to  claim 32 , wherein said beneficial agnet includes antithrombins. 
   
   
       35 . The expandable medical device according to  claim 32 , wherein said beneficial agent includes at least one of large molecules, microspheres, beneficial agents within a biodegradable polymer carrier, and cells, said plurality of openings forming a protected receptor for loading said beneficial agent therein. 
   
   
       36 . The expandable medical device according to  claim 32 , wherein said beneficial agent defines a first beneficial agent, and further comprising a surface coating of a second beneficial agent on said expandable medical device. 
   
   
       37 . The expandable medical device according to  claim 27 , wherein said at least one cylindrical tube includes two cylindrical tubes interconnected by a bridging element. 
   
   
       38 . The expandable medical device according to  claim 27 , wherein the expandable medical device is formed of Nitinol. 
   
   
       39 . The expandable medical device according to  claim 27 , wherein the expandable medical device is formed of stainless steel.