Medical Implant Such a Stent

Abstract

A medical implant such as a self-expanding shape memory alloy stent with a strut matrix formed by cut patterns in a wall of a tubular workpiece ( 12 ) can be enhanced by arranging for the line of the laser beam when cutting the struts ( 62 ) to be one that does not pass through the longitudinal rotational axis ( 10 ) of the tubular workpiece. Such “off-axis-” cutting can modify the cross-sectional shape and area of each strut, along its length. Such modulation can enhance the fatigue resistance of the stent matrix, or increase the radial force that the stent matrix is capable of exerting on bodily tissue within which it is implanted.

1 . A medical implant that defines a lumen with a longitudinal center axis having a matrix of elongate struts wherein each strut has a thickness between a luminal surface and an abluminal surface, and opposed lengthwise flank surfaces, one on each side of the strut
 the flank surfaces being formed by a jet cutter; and   at least a portion of at least one of the flank surfaces has a plane that does not intercept the longitudinal center axis.   
   
   
       2 . The medical implant according to  claim 1  wherein the flank surfaces are formed from a tube stock having a diameter corresponding to the diameter of the expanded medical implant. 
   
   
       3 . The medical implant claimed in  claim 1 , wherein the flank surfaces are formed such as to obtain one dimension in the circumferential direction that is greater than if the planes of the flank surface would intercept the longitudinal center axis. 
   
   
       4 . The medical implant claimed in  claim 1 , wherein at least one of the flank surfaces has a discontinuity. 
   
   
       5 . The medical implant claimed in  claim 1 , wherein at least one of the flank surfaces has a sharp cutting edge. 
   
   
       6 . The medical implant claimed in  claim 1 , wherein the implant is a stent. 
   
   
       7 . A method of forming a medical implant from a tubular workpiece that has a longitudinal center axis, the method including the step of using a jet cutter to cut a matrix of struts within an annular wall of the workpiece,
 the method being characterized by the steps of:   arranging the line of the jet cutter so as not to intercept the longitudinal center axis; and   translating the workpiece relative to the arranged line of action, to create a flank surface of a strut within the matrix wherein at least a portion of the flank surfaces has a plane or tangent that does not intercept the longitudinal center axis.   
   
   
       8 . The method as claimed in  claim 7 , wherein the flank surfaces are formed from a tube stock having a diameter corresponding to the diameter of the expanded medical implant. 
   
   
       9 . The medical implant according to  claim 7 , forming the flank surfaces such as to obtain one dimension in the circumferential direction that is greater than if the planes of the flank surface would intercept the longitudinal center axis. 
   
   
       10 . The method as claimed in  claim 7 , forming at least one of the flank surfaces with a discontinuity.