Cold-molding process for loading a stent onto a stent delivery system

Abstract

A method of making a stent delivery system is provided in which a delivery catheter has a balloon that extends non-uniformly into interstices of a stent. In accordance with the method a balloon/stent/crimping tube assembly is placed in a crimping tool, the balloon is inflated, and the crimping tool is actuated to compress the stent on the outside of the balloon without application of heat or chemicals, thereby causing creases of the balloon to extend non-uniformly into the interstices of the stent. Optionally, pillows may be formed in the balloon to prevent longitudinal movement of the stent with respect to the balloon during intravascular delivery. One or more secondary crimpings also may be performed to achieve a smoother delivery profile.

What is claimed is: 
     
         1 . A method of fabricating a stent delivery system comprising:
 providing an apparatus comprising a stent and a delivery catheter having an inflatable balloon;   disposing the stent about the inflatable balloon;   placing the balloon and stent within a crimping tool;   inflating the balloon;   actuating the crimping tool to compress the stent on the outside of the balloon at a substantially constant temperature, thereby causing the balloon to extend non-uniformly into interstices of the stent; and   deflating the balloon while the crimping tool is still actuated, thereby securing non-uniform creases of the balloon within the interstices of the stent and forming a stent delivery system.   
     
     
         2 . The method of  claim 1  further comprising removing the stent delivery system from the crimping tool. 
     
     
         3 . The method of  claim 1 , wherein deflating the balloon further comprises forming proximal and/or distal pillows. 
     
     
         4 . The method of  claim 1  further comprising performing secondary crimping. 
     
     
         5 . The method of  claim 4 , wherein secondary crimping comprises:
 de-actuating the crimping tool; and   re-actuating the crimping tool to further compress the stent on the outside of the balloon.   
     
     
         6 . The method of  claim 5  further comprising de-actuating the crimping tool. 
     
     
         7 . The method of  claim 1 , wherein inflating the balloon comprises partially inflating the balloon. 
     
     
         8 . The method of  claim 7  wherein partially inflating the balloon comprises inflating the balloon at a pressure below a preferred rated burst pressure of the balloon. 
     
     
         9 . The method of  claim 8 , wherein inflating the balloon occurs after placing the balloon and stent within the crimping tool. 
     
     
         10 . The method of  claim 9 , further comprising de-actuating the crimping tool. 
     
     
         11 . The method of  claim 10 , wherein the stent comprises:
 a proximal end portion having a plurality of interstices defined therein;   a distal end portion having a plurality of interstices defined therein; and   an intermediate portion having a plurality of interstices defined therein.   
     
     
         12 . The method of  claim 11 , wherein the creases of the balloon extend non-uniformly into interstices of the stent along a length of the stent. 
     
     
         13 . The method of  claim 12 , wherein the creases do not extend within each of the interstices of the stent. 
     
     
         14 . The method of  claim 10  further comprising performing secondary crimping. 
     
     
         15 . The method of  claim 14 , wherein secondary crimping comprises re-actuating the crimping tool to further compress the stent on the outside of the balloon. 
     
     
         16 . The method of  claim 10  wherein actuating the crimping tool comprises actuating the crimping tool in sections along a length of the stent. 
     
     
         17 . A method of fabricating a stent delivery system comprising:
 providing an apparatus comprising a stent and a delivery catheter having an inflatable balloon;   disposing the stent about the inflatable balloon;   placing an elastic crimping tube over the stent and balloon;   placing the balloon, stent, and elastic crimping tube within a crimping tool; inflating the balloon;   actuating the crimping tool to compress the stent on the outside of the balloon at a substantially constant temperature, thereby causing the balloon to extend non-uniformly into the interstices of the stent; and   deflating the balloon while the crimping tool is still activated, thereby securing non-uniform creases of the balloon within the interstices of the stent and forming the stent delivery system.   
     
     
         18 . The method of  claim 17  further comprising deactuating the crimping tool and removing the stent delivery system from the elastic crimping tube. 
     
     
         19 . The method of  claim 17 , wherein deflating the balloon further comprises forming proximal and/or distal pillows. 
     
     
         20 . The method of  claim 17  further comprising performing secondary crimping. 
     
     
         21 . The method of  claim 20 , wherein secondary crimping comprises:
 placing a semi-rigid crimping tube over the stent delivery system;   placing the stent delivery system and semi-rigid crimping tube within the crimping tool; and   re-actuating the crimping tool to further compress the stent on the outside of the balloon.   
     
     
         22 . The method of  claim 21  further comprising de-actuating the crimping tool and removing the stent delivery system from the semi-rigid crimping tube. 
     
     
         23 . The method of  claim 21 , wherein re-actuating the crimping tool comprises actuating the crimping tool in sections along a length of the stent delivery system. 
     
     
         24 . The method of  claim 17 , wherein inflating the balloon further comprises partially inflating the balloon. 
     
     
         25 . A method of fabricating a stent delivery system comprising:
 providing apparatus comprising a stent and a delivery catheter having an inflatable balloon;   disposing the stent about the inflatable balloon;   placing the balloon and stent within a crimping tool;   inflating the balloon;   deflating the balloon; and   actuating the crimping tool to compress the stent on the outside of the balloon at a substantially constant temperature, thereby securing non-uniform creases of the balloon within the interstices of the stent and forming the stent delivery system.   
     
     
         26 . The method of  claim 25 , wherein inflating the balloon comprises partially inflating the balloon. 
     
     
         27 . The method of  claim 26  wherein partially inflating the balloon comprises inflating the balloon at a pressure below a preferred rated burst pressure of the balloon. 
     
     
         28 . The method of  claim 27 , wherein inflating the balloon occurs after disposing the stent about the balloon. 
     
     
         29 . The method of  claim 28 , further comprising de-actuating the crimping tool. 
     
     
         30 . The method of  claim 29 , wherein the stent comprises:
 a proximal end portion having a plurality of interstices defined therein;   a distal end portion having a plurality (if interstices defined therein; and   an intermediate portion having a plurality of interstices defined therein.   
     
     
         31 . The method of  claim 30 , wherein the creases of the balloon extend non-uniformly into interstices of the stent along the length of the stent. 
     
     
         32 . The method of  claim 31 , wherein the creases do not extend within each of the interstices of the stent. 
     
     
         33 . The method of  claim 29  further comprising performing secondary crimping. 
     
     
         34 . The method of  claim 33 , wherein secondary crimping comprises re-actuating the crimping tool to further compress the stent on the outside of the balloon. 
     
     
         35 . The method of  claim 29  wherein actuating the crimping tool comprises actuating the crimping tool in sections along a length of the stmt. 
     
     
         36 . A method of fabricating a stent delivery system comprising:
 providing a crimping tool;   disposing a stent about an inflatable balloon of a delivery catheter, the stent comprising a proximal end portion, a distal end portion, and an intermediate portion, each portion having a plurality of interstices defined therein;   placing the balloon and the stent within the crimping tool;   partially inflating the balloon to a pressure less than a preferred rated burst pressure of the balloon after disposing the stent about the inflatable balloon;   actuating the crimping tool to compress the stent on the outside of the balloon while the balloon is partially inflated to the pressure less than the preferred rated burst pressure of the balloon;   depressurizing the balloon while the crimping tool is still actuated; and   de-actuating the crimping tool after the balloon is depressurized,   
       wherein upon conclusion of the crimping process the balloon extends non-uniformly into the plurality of interstices along the length of the stent. 
     
     
         37 . The method of  claim 36 , wherein the balloon does not extent into each of the plurality of interstices. 
     
     
         38 . The method of  claim 36 , further comprising re-actuating the crimping tool to further compress the stent on the outside of the balloon. 
     
     
         39 . The method of  claim 36 , wherein actuating the crimping tool comprises actuating t crimping tool in sections along a length of the stent. 
     
     
         40 . A method of crimping a stent onto a balloon of a delivery catheter, the method comprising:
 providing a crimping tool;   disposing a stent about an inflatable balloon of a delivery catheter;
 wherein the stem includes: 
 a first portion of interconnected struts located at a first end of the stent, the first portion of interconnected struts defining interstices between adjacent interconnected struts of the first portion; 
 a second portion of the interconnected struts located at a second end of the stent, the second portion of interconnected struts defining interstices between adjacent interconnected struts of the second portion; and 
 a third portion of interconnected struts located intermediate the first portion and the second portion, the third portion of interconnected struts defining interstices between adjacent interconnected struts of the third portion: 
   positioning the stent and the inflatable balloon of the delivery catheter within the crimping tool;   pressurizing the inflatable balloon to a partially inflated state at a pressure lower than a preferred rated burst pressure of the inflatable balloon after disposing the stent about the inflatable balloon;   actuating the crimping tool to crimp the stent onto the inflatable balloon while the balloon is in the partially inflated state;   depressurizing the inflatable balloon while the crimping tool remains actuated; and   de-actuating the crimping tool after the inflatable balloon is depressurized;   
       wherein upon conclusion of the crimping process the balloon extends non-uniformly into the interstices of the first portion of the stent proximate the first end of the stent, and wherein the balloon extend non-uniformly into the interstices of the second portion of the stent proximate the second end of the stent. 
     
     
         41 . The method of  claim 40 , wherein upon conclusion of the crimping process creases of the balloon do not extend radially outward within the interstices of the third portion of the stent. 
     
     
         42 . The method of  claim 40 , further comprising re-actuating the crimping tool to further compress the stent On the outside of the balloon. 
     
     
         43 . The method of  claim 40 , wherein actuating the crimping tool comprises actuating the crimping tool in sections along a length of the stent.