Crush recoverable polymer scaffolds

Abstract

A medical device includes a polymer scaffold crimped to a catheter having an expansion balloon. The scaffold, after being deployed by the balloon, provides a crush recovery of about 90% after the diameter of the scaffold has been pinched or crushed by 50%. The scaffold has a pattern including an asymmetric closed cell connecting links connecting the closed cells.

1 - 22 . (canceled) 
     
     
         23 . A balloon-expandable medical device for being implanted in a peripheral vessel of the body, comprising:
 a scaffold formed from a polymer tube
 configured for being crimped to a balloon, 
 the scaffold having a pattern of interconnected elements comprising rings interconnected by links, and 
 the scaffold having an expanded diameter when plastically deformed from a crimped state by the balloon, 
   wherein the scaffold attains greater than 90% of the expanded diameter after being crushed by an amount equal to at least 33% of the expanded diameter; and   wherein at least a portion of the links include at least one hinge point or a pre-designated fracture point formed in the link.   
     
     
         24 . The medical device of  claim 23 , wherein the interconnected elements further comprise struts forming the rings, and wherein an aspect ratio (AR) of the width to wall thickness of a strut is between 0.4 and 1.4. 
     
     
         25 . The medical device of  claim 23 , wherein a scaffold wall thickness is between 0.008 inches and 0.014 inches and the scaffold expanded diameter is between 5 mm and 8 mm. 
     
     
         26 . The medical device of  claim 24 , wherein the rings include crowns, nd wherein the crowns have a maximum crown angle between about 90 degrees and 115 degrees when the scaffold has the expanded diameter. 
     
     
         27 . The medical device of  claim 23 , wherein the rings are formed by struts, the rings include crowns having crown angles, and there are no more than 9 crowns in a ring and 3 links connecting any ring to an adjacent ring, and
 wherein prior to crimping the scaffold to the balloon the scaffold has an outer diameter of 8 to 10 mm, the crown angles for rings of the scaffold are between 90 and 115 degrees, and   the scaffold has a wall thickness of at least 0.008 in.   
     
     
         28 . The medical device of  claim 27 ,
 wherein a network of struts and links form a plurality of closed cells, each closed cell having a first end circumferentially spaced from an opposing second end and a pair of bending elements extending between the circumferentially spaced ends, each bending element forming at least two crowns,   wherein the first and second ends of a closed cell are shared with an adjacent cell, and   wherein adjacent rings are connected to each other by links such that the links connecting a ring to its two, adjacent rings are not co-linear with each other.   
     
     
         29 . The medical device of  claim 23 , wherein the interconnected elements include a plurality of asymmetric closed cells having bending elements comprising struts forming crowns, unconnected crowns, Y-crowns and W-crowns,
 wherein each of the asymmetric closed cells includes more than one unconnected crown disposed between a Y-crown and a W-crown, and the asymmetry of the closed cell is with respect to a plurality of links connecting the closed cell to adjacent closed cells.   
     
     
         30 . The medical device of  claim 23 , wherein the scaffold has a ratio of pinching stiffness to wall thickness times tube diameter of 0.08:1 to 0.18:1. 
     
     
         31 . The medical device of  claim 23 , wherein the scaffold has a pre-crimp diameter of 7 mm and 10 mm,
 the scaffold is fabricated to have a pair of adjacent rings, wherein the ring pair forms no more than three closed cells, and   the scaffold is fabricated from a tube comprising PLLA.   
     
     
         32 . The medical device of  claim 31 , wherein the scaffold has a wall thickness of at least 0.008 inches. 
     
     
         33 . The medical device of  claim 23 , wherein the polymer is PLLA, or a blend of PLLA with a polymer having a lower T g  than PLLA, or a block co-polymer, or a multi-layered structure having different T g  values for the material of different layers. 
     
     
         34 . The medical device of  claim 33 , wherein the block co-polymer or blend is PLLA with PEG (poly-ethylene glycol). 
     
     
         35 . The medical device of  claim 23 , wherein the at least a portion of the links each include a hinge point formed by a U-shaped portion of the link. 
     
     
         36 . The medical device of  claim 23 , wherein the at least a portion of the links each include two hinge points comprising an S-shaped portion of the link. 
     
     
         37 . The medical device of  claim 23 , wherein hinge points are arranged amongst the links so that the scaffold has a reduced bending stiffness about two axes. 
     
     
         38 . The medical device of  claim 37 , wherein the at least a portion of the links are between 5-100% of the links in the scaffold. 
     
     
         39 . A peripherally implantable medical device, comprising:
 a crimped scaffold that when plastically deformed by a balloon forms a scaffold having an expanded diameter, wherein,
 the scaffold regains more than 90% of the expanded diameter after being crushed to at least 67% of the expanded diameter, 
 the scaffold comprises PLLA, 
 the scaffold has a pre-crimp diameter of 7 to 10 mm, 
 the scaffold has struts and links, wherein a strut and/or link has a width to thickness ratio of between about 0.8 and 1.4, and 
 at least a portion of the links include one of a U-shaped portion, S-shaped portion, or a pre-designated fracture point formed in the link. 
   
     
     
         40 . The medical device of  claim 39 , wherein at least a portion of the links include a pre-designated fracture point formed in the link, and
 wherein each of the at least a portion of the links have a first section comprising the pre-designated fracture point and a first moment of inertia (MOI1) with respect to a bending axis, and a second section comprising a second moment of inertia (MOI2) with respect to the bending axis, and MOI1<MOI2.   
     
     
         41 . The medical device of  claim 40 , wherein the first section is formed by voids formed in the link. 
     
     
         42 . The medical device of  claim 39 , wherein the at least a portion of the links are between 5-100% of the links in the scaffold.