Delivery system for a self-expanding medical device

Abstract

A delivery system is provided for self-expanding medical devices, such as stents. The delivery system has a restraining sheath that maintains the stent in a compressed state prior to deployment. The restraining sheath terminates distally from the deployment handle, and a wire connects the restraining sheath to the deployment handle. The restraining sheath is withdrawn from the stent to deploy the stent by pulling the wires proximally at the deployment handle.

We claim: 
     
         1 . A self-expanding medical device delivery system, comprising:
 a self-expanding medical device comprising a distal end, a proximal end and a length therebetween;   an inner catheter extending proximally from said medical device to a deployment handle, said inner catheter comprising a stop surface adjacent said proximal end of said medical device and adapted to prevent said medical device from moving proximally during deployment of said medical device;   a restraining sheath comprising a first portion extending over said medical device and adapted to prevent said medical device from self-expanding prior to deployment of said medical device and a second portion extending proximally of said medical device to a proximal end of said restraining sheath, said second portion being at least as long as said length of said medical device, said second portion having a constant outer profile that is smaller than a constant outer profile of said first portion, and the proximal end of said restraining sheath terminating distally from said deployment handle;   a wire adhered to the second portion of said restraining sheath and extending proximally from said restraining sheath to said deployment handle; and   a covering sheath extending from said restraining sheath to said deployment handle, said covering sheath extending over and disposed radially outward from an outer surface of at least said proximal end of said restraining sheath;   wherein said medical device is deployed by pulling said wire proximally to withdraw said restraining sheath proximally away from said medical device, and   wherein a longitudinal space inside said covering sheath is formed to receive said movable restraining sheath withdrawn proximally away from said medical device.   
     
     
         2 . The self-expanding medical device delivery system according to  claim 1 , wherein said medical device is a stent. 
     
     
         3 . The self-expanding medical device delivery system according to  claim 1 , wherein said inner catheter comprises a guidewire lumen extending from a distal end of said inner catheter to said deployment handle. 
     
     
         4 . The self-expanding medical device delivery system according to  claim 1 , wherein said medical device is deployed by said deployment handle winding up the wire, thereby pulling said wire proximally to withdraw said restraining sheath proximally away from said medical device. 
     
     
         5 . The self-expanding medical device delivery system according to  claim 1 , further comprising a low friction liner adhered to said restraining sheath and extending along said length of said medical device and contacting an outer surface of said medical device, wherein said restraining sheath comprises a thermoplastic polymer covering said wire and said liner. 
     
     
         6 . The self-expanding medical device delivery system according to  claim 1 , wherein said restraining sheath further comprises a tapered portion between said first portion and said second portion. 
     
     
         7 . The self-expanding medical device delivery system according to  claim 1 , wherein said covering sheath is fixed to said deployment handle and does not move during deployment of said medical device, said covering sheath extending over only a portion of said restraining sheath disposed proximally from said medical device. 
     
     
         8 . The self-expanding medical device delivery system according to  claim 7 , wherein said covering sheath comprises an inner circumference and an outer circumference that are both generally constant along an entire length of said covering sheath. 
     
     
         9 . The self-expanding medical device delivery system according to  claim 8 , wherein a distal end of said covering sheath comprises an atraumatic taper and a close fitting inner diameter around said restraining sheath that presents a smooth transition between said restraining sheath and said covering sheath. 
     
     
         10 . A self-expanding medical device delivery system, comprising:
 a self-expanding medical device comprising a distal end, a proximal end and a length therebetween;   an inner catheter extending proximally from said medical device to a deployment handle, said inner catheter comprising a stop surface adjacent said proximal end of said medical device and adapted to prevent said medical device from moving proximally during deployment of said medical device;   a restraining sheath comprising a first portion extending over said medical device and adapted to prevent said medical device from self-expanding prior to deployment of said medical device and a second portion extending proximally of said medical device to a proximal end of said restraining sheath, said second portion having a constant outer profile that is smaller than a constant outer profile of said first portion, and the proximal end of said restraining sheath terminating distally from said deployment handle; and   at least one wire adhered to the second portion of said restraining sheath and extending proximally from said restraining sheath to said deployment handle;   wherein said medical device is deployed by pulling said at least one wire proximally to withdraw said restraining sheath proximally away from said medical device; and   wherein said restraining sheath comprises a thermoplastic polymer, and a coil is embedded within the thermoplastic polymer and extends along at least a portion of said length of said medical device.   
     
     
         11 . The self-expanding medical device delivery system according to  claim 10 , further comprising a low friction liner disposed along an inner surface of said restraining sheath and extending along said length of said medical device and contacting an outer surface of said medical device. 
     
     
         12 . The self-expanding medical device delivery system according to  claim 10 , wherein said stop surface is a metal or polymer ring bonded to said inner catheter. 
     
     
         13 . The self-expanding medical device delivery system according to  claim 10 , wherein said medical device is deployed by said deployment handle winding up said at least one wire, thereby pulling said at least one wire proximally to withdraw said restraining sheath proximally away from said medical device. 
     
     
         14 . The self-expanding medical device delivery system according to  claim 10 , wherein said restraining sheath further comprises a tapered portion between said first portion and said second portion. 
     
     
         15 . The self-expanding medical device delivery system according to  claim 10 , wherein said medical device is a stent. 
     
     
         16 . A self-expanding medical device delivery system, comprising:
 a self-expanding medical device comprising a distal end, a proximal end and a length therebetween;   an inner catheter extending proximally from said medical device to a deployment handle, said inner catheter comprising a stop surface adjacent said proximal end of said medical device and adapted to prevent said medical device from moving proximally during deployment of said medical device;   a restraining sheath comprising a first portion extending over said medical device and adapted to prevent said medical device from self-expanding prior to deployment of said medical device and a second portion extending proximally of said medical device to a proximal end of said restraining sheath, said second portion having a constant outer profile that is smaller than a constant outer profile of said first portion, and the proximal end of said restraining sheath terminating distally from said deployment handle;   at least one wire adhered to the second portion of said restraining sheath and extending proximally from said restraining sheath to said deployment handle; and   a covering sheath extending from said restraining sheath to said deployment handle and fixed to said deployment handle, said covering sheath extending over and disposed radially outward from an outer surface of at least said proximal end of said restraining sheath, a distal end of said covering sheath provided with an inner diameter that closely fits onto an outer diameter of said proximal end of said restraining sheath, and the distal end of said covering sheath including an atraumatic tapered end that provides a smooth transition between said restraining sheath and said covering sheath;   wherein said medical device is deployed by pulling said at least one wire proximally to withdraw said restraining sheath proximally away from said medical device, and   wherein a longitudinal space inside said covering sheath is formed to receive said movable restraining sheath withdrawn proximally away from said medical device.   
     
     
         17 . The self-expanding medical device delivery system according to  claim 16 , wherein said covering sheath comprises a thermoplastic polymer, and a coil is embedded within the thermoplastic polymer. 
     
     
         18 . The self-expanding medical device delivery system according to  claim 16 , wherein said covering sheath comprises a first portion and a second portion extending proximally of said first portion, said second portion of said covering sheath having an outer profile that is smaller than an outer profile of said first portion of said covering sheath. 
     
     
         19 . The self-expanding medical device delivery system according to  claim 16 , wherein said deployment handle includes a flushing port in fluid communication with an annular space between said covering sheath and said inner catheter and between said restraining sheath and said inner catheter. 
     
     
         20 . The self-expanding medical device delivery system according to  claim 16 , wherein said medical device is deployed by said deployment handle winding up said at least one wire, thereby pulling said at least one wire proximally to withdraw said restraining sheath proximally away from said medical device.