Polymer stent with tunable axial and radial flexibility

Abstract

Stents are provided which include geometric segments comprising radial elements and axial elements. Both the radial and axial elements are optionally characterized by a width and a thickness, and the widths and thicknesses of the radial and axial elements are capable of being fixed independently of one another, permitting the axial and radial flexibility of the stent to be controlled independently of one another.

What is claimed is: 
     
         1 . A biliary stent, comprising:
 a plurality of helical segments and at least one non-helical segment interposed between adjacent helical segments or disposed at an end of the biliary stent,   wherein the biliary stent comprises a shape memory polymer and is moveable from a compressed configuration to an expanded configuration in which at least one of a diameter of the biliary stent and a length of the biliary stent is increased relative to the compressed configuration.   
     
     
         2 . The biliary stent of  claim 1 , wherein the at least one non-helical segment is a retentive tang disposed at an end of the stent. 
     
     
         3 . The biliary stent of  claim 1 , wherein the at least one non-helical segment is one of a tube and a strut. 
     
     
         4 . The biliary stent of  claim 1 , wherein the fixing temperature of the shape memory polymer is greater than or equal to 37° Centigrade. 
     
     
         5 . The biliary stent of  claim 1 , wherein the biliary stent assumes the expanded configuration when disposed within a body lumen of a patient. 
     
     
         6 . A biliary stent, comprising:
 a plurality of geometric segments, each of the plurality of geometric segments comprising   at least one radial element extending about a circumference of the biliary stent, the at least one radial element characterized by at least one of a width and a thickness; and   at least one axial element extending along at least a portion of a length of the biliary stent, the at least one axial element characterized by at least one of a width and a thickness.   
     
     
         7 . The biliary stent according to  claim 6 , wherein (a) the biliary stent comprises a shape-memory polymer, (b) the biliary stent is configured to move between a compressed configuration characterized by a compressed diameter and a compressed length and an expanded configuration characterized by an expanded diameter and an expanded length, at least one of which is greater than the compressed diameter or the compressed length, respectively, and (c) at least one of the width and the thickness of the at least one radial element can be modified without affecting the axial flexibility of the biliary stent. 
     
     
         8 . The biliary stent according to  claim 7 , wherein the fixing temperature of the shape memory polymer is greater than or equal to 37° Centigrade. 
     
     
         9 . The biliary stent according to  claim 7 , wherein the biliary stent assumes the expanded configuration when disposed within a body lumen of a patient, the expanded diameter is greater than the compressed diameter and the expanded length is less than or equal to the compressed length. 
     
     
         10 . The biliary stent according to  claim 6 , wherein the at least one radial element is one of a hoop and a coil spring. 
     
     
         11 . The biliary stent according to  claim 6 , wherein the at least one axial element is one of a strut and a tube. 
     
     
         12 . The biliary stent according to  claim 6 , wherein at least one of the width of the radial element, the thickness of the at least one radial element, the width of the at least one axial element and the thickness of the at least one axial element varies along the length of the biliary stent. 
     
     
         13 . A biliary stent, comprising:
 a plurality of hoops extending radially about a circumference of the biliary stent, each of the plurality of hoops having a hoop width and a hoop thickness; and   a plurality of struts disposed between and connecting the hoops, each strut having a strut width and a strut thickness,   wherein the biliary stent includes a shape memory polymer.   
     
     
         14 . The biliary stent of  claim 13 , wherein the biliary stent has a compressed configuration characterized by a first diameter and a first length and an expanded configuration characterized by a second diameter and a second length, wherein at least one of the second diameter and the second length is greater than the first diameter or the first length, respectively. 
     
     
         15 . The biliary stent of  claim 14 , wherein the biliary stent assumes the expanded configuration when disposed within a body lumen of a patient, the second diameter is greater than the first diameter, and the second length is less than or equal to the first length. 
     
     
         16 . The biliary stent of  claim 13 , wherein the plurality of hoops and the plurality of struts form a plurality of diamond-shaped voids. 
     
     
         17 . The biliary stent of  claim 13 , wherein the hoop width is different than the strut width. 
     
     
         18 . The biliary stent of  claim 13 , wherein the hoop thickness is different than the strut thickness. 
     
     
         19 . The biliary stent of  claim 13 , wherein at least one of the hoop width, hoop thickness, strut width and strut thickness varies along a length of the stent. 
     
     
         20 . The biliary stent of  claim 13 , wherein the shape-memory polymer has a fixing temperature greater than or equal to 37° Centigrade.