Expandable medical device with beneficial agent delivery mechanism

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 which is visible in x-ray and fluoroscope images, the device comprising: 
 a plurality of struts arranged to form an expandable cylindrical tube, the struts having a strut width in a circumferential direction; and    a plurality of ductile hinges connecting the plurality of struts, wherein the struts and ductile hinges have a thickness in a radial direction of the cylindrical tube of at least 0.003 inches (0.0762 mm) the ductile hinges having a hinge thickness and a substantially constant width in a circumferential dimension along a portion of a hinge length which is at least ⅓ a total hinge length, wherein the hinge width is smaller than the strut width such that as the device is expanded from a first diameter to a second diameter the ductile hinges experience plastic deformation while the struts are not plastically deformed.    
     
     
         28 . The expandable medical device according to  claim 27 , wherein the device is formed of stainless steel.  
     
     
         29 . The expandable medical device according to  claim 27 , wherein the thickness of the struts and ductile hinges is at least 0.005 inches (0.127 mm).  
     
     
         30 . The expandable medical device according to  claim 27 , wherein the elongated struts include a beneficial agent for delivery to a patient.  
     
     
         31 . The expandable medical device according to  claim 27 , wherein a transition between the cross sectional area of the struts and the cross sectional area of the ductile hinges is an abrupt transition which extends less than 10 percent of a length of a strut.  
     
     
         32 . The expandable medical device according to  claim 27 , wherein the plurality of ductile hinges are curved prismatic beams.  
     
     
         33 . The expandable medical device according to  claim 27 , wherein a ratio of a length of the ductile hinges to a length of the axial struts is 1:6 or less.  
     
     
         34 . The expandable medical device according to  claim 27 , wherein the ductile hinges are designed to deform plastically upon radial expansion or compression of the expandable medical device while the elongated struts experience substantially no plastic deformation upon radial expansion or compression.  
     
     
         35 . An expandable medical device comprising: 
 a plurality of elongated beams, the plurality of elongated beams joined together to form a substantially cylindrical device which is expandable from a first diameter to a second diameter, the plurality of elongated beams each having a beam width in a circumferential direction; and    a plurality of ductile hinges connecting the plurality of beams together in a substantially cylindrical device, the ductile hinges having a hinge thickness and a substantially constant width in a circumferential dimension along a portion of a hinge length which is at least ⅓ a total hinge length, wherein the hinge width is the hinge thickness and the hinge width is smaller than the beam width such that as the device is expanded from the first diameter to the second diameter the ductile hinges experience plastic deformation while the beams are not plastically deformed.    
     
     
         36 . The expandable medical device according to  claim 35 , further comprising an abrupt transition between each of the elongated beams and each of the ductile hinges.  
     
     
         37 . The expandable medical device according to  claim 35 , wherein the ductile hinges are each in the shape of a curved prismatic beam.  
     
     
         38 . The expandable medical device according to  claim 35 , wherein expansion of the substantially cylindrical device from the first diameter to the second diameter which is at least two times the first diameter results in substantially no axial contraction.  
     
     
         39 . The expandable medical device according to  claim 35 , wherein the hinge width is at least 50% smaller than the beam width.  
     
     
         40 . The expandable medical device according to  claim 35 , wherein the device is expandable by a balloon catheter pressurized by an inflation pressure of 1 to 5 atmospheres.  
     
     
         41 . The expandable medical device according to  claim 35 , wherein the elongated struts include a beneficial agent for delivery to a patient.