Tapering stent

Abstract

A stent includes a high radial force segment and a highly flexible segment, where the diameters of the high radial force segment and the highly flexible segment are different. For example, the stent may be formed from a tube having varying diameters as it extends distally combined with increased strut density to achieve increased flexibility distally while reducing loss of radial stiffness. The stent may further be placed with an additional stent segment, where the additional stent segment has a radial force similar to the radial force of the highly flexible force segment.

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         13 . A method of making a medical device, the method comprising:
 selecting an elongate tubular structure defining a lumen therethrough and having a constant inside diameter and outside diameter;   grinding an outside of an elongate tubular structure to create a constant diameter of a flexible region, a constant diameter of a firm region, a transition region between the flexible region and the firm region, wherein the constant diameter of the flexible region is less than the constant diameter of the firm region; and   cutting a plurality of struts out of the elongate tubular structure;   wherein grinding and cutting contribute to the firm region having a radial stiffness greater than a radial stiffness of the flexible region and a flexibility lesser than a flexibility of the flexible region.   
     
     
         14 . The method of  claim 13 , wherein grinding results in a diameter of the transition region to be constant and less than the diameter of the firm region and greater than the diameter of the flexible region. 
     
     
         15 . The method of  claim 13  wherein the grinding is centerless grinding. 
     
     
         16 . The method of  claim 13 , wherein cutting the plurality of struts includes cutting struts with fewer connections in the flexible region than in the firm region. 
     
     
         17 . The method of  claim 16 , wherein cutting the plurality of struts includes cutting struts with fewer connections in the transition region than the firm region and more connections in the transition region than the flexible region. 
     
     
         18 . The method of  claim 13 , wherein cutting the plurality of struts is configured to mediate a proportional loss of radial stiffness in a distal direction along the elongate tubular structure to be less than a proportional increase in flexibility in the distal direction. 
     
     
         19 . The method of  claim 13 , further including stiffening a first free end and a second free end to have a radial stiffness greater than the firm, transition and flexible regions extending therebetween. 
     
     
         20 . The method of  claim 13 , further including compressing the medical device into a delivery catheter. 
     
     
         21 . The method  claim 13 , wherein the differing diameters of the firm region, the transition region and the flexible region result from grinding a wall structure of the elongate tube to have a first constant thickness in the firm region, a second constant thickness in the transition region and a third constant thickness in the flexible region. 
     
     
         22 . The method of  claim 13 , further comprising grinding the wall structure to have regions of varying wall thickness between the firm region and the transition region and between the transition region and the flexible regions. 
     
     
         23 . The method of  claim 13 , wherein, after grinding and cutting, the radial stiffness of the firm region is sufficient to mediate May-Thurner Syndrome. 
     
     
         24 . The method of  claim 13 , wherein, after grinding and cutting, the flexible region has a flexibility that is greater than a flexibility of the firm region. 
     
     
         25 . The method of  claim 24 , wherein, after grinding and cutting, the transition region has a flexibility that is greater than the flexibility of the firm region and less than the flexibility of the flexible region. 
     
     
         26 . The method of  claim 25 , wherein, after grinding and cutting, a difference between the flexibility of the flexible region and the firm region is greater than a difference between the radial stiffness of the firm region and the radial stiffness of the flexible region. 
     
     
         27 . The method of  claim 26 , wherein, after grinding and cutting, flexibility of the elongate tubular wall structure increases faster than radial stiffness drops progressing from the firm region toward the flexible region. 
     
     
         28 . The method of  claim 13 , wherein, after cutting, the elongate tubular wall structure is defined by a plurality of interconnected struts. 
     
     
         29 . The method of  claim 28 , wherein, after cutting, the interconnected struts have a greater density in the flexible region than the firm region. 
     
     
         30 . The method of  claim 28 , wherein, after cutting, the interconnected struts have a greater frequency of interconnection in the flexible region than the firm region. 
     
     
         31 . The method of  claim 13 , wherein the elongate tubular wall structure includes a first free end adjacent the firm region and a second free end adjacent the flexible region and wherein, after grinding, the first and second free ends have a radial stiffness greater than the firm, transition, and flexible regions.