Implant delivery system

Abstract

A system and method of delivering and detaching an implant within a body of a patient is described. A tether connects an implant with a delivery device. The delivery device includes a heater coil through which the tether passes. The inner diameter of the heater coil is about the same size or slightly larger than the outer diameter of the tether, allowing the tether to more efficiently break the tether during delivery.

What is claimed is: 
     
         1 . A delivery system for an implant comprising:
 an elongated pusher having a distal end and a proximal end;   an implant positioned at said distal end of said elongated pusher;   a resistance heating element having a first plurality of coils that each have a first internal diameter and a second plurality of coils that each have a second internal diameter that is smaller than said first internal diameter; said resistance heating element increasing in temperature via application of direct current;   a tether member connected to said elongated pusher, passing through said first plurality of coils, passing through said second plurality of coils, and being attached to said implant.   
     
     
         2 . The delivery system of  claim 1 , further comprising a first wire connected to a distal end of said heating element and a second wire connected to a proximal end of said heating element; wherein said first wire and said second wire supply 
     
     
         3 . The delivery system of  claim 2 , further comprising a selectively actuated power supply that is connectable with said first wire and said second wire. 
     
     
         4 . The delivery system of  claim 1 , wherein said tether has an external diameter of about 0.004 inch, said first internal diameter is about 0.007 inch and said second internal diameter is about 0.005 inch. 
     
     
         5 . The delivery system of  claim 1 , wherein said heating element is fixed along a side of said elongated pusher. 
     
     
         6 . The delivery system of  claim 1 , wherein said implant is a stent having a plurality of cells and wherein said tether member is positioned through at least one of said plurality of cells. 
     
     
         7 . The delivery system of  claim 6 , wherein said tether member passes through multiple cells of said plurality of cells. 
     
     
         8 . The delivery system of  claim 1 , wherein said implant is an embolic microcoil. 
     
     
         9 . A delivery system for an implant comprising:
 a pusher having an elongated shape;   a proximal end of said pusher being connectable to a DC power supply;   an implant positioned at a distal end of said pusher;   a heater comprising a lumen formed from a first region and a second region; said first region have a first internal diameter and said second region having a second internal diameter that is smaller than said first internal diameter;   a tether connected to said pusher and extending through said lumen of said first region and said second region; said tether connecting to said implant and being breakable by activation of said heater by said DC power supply.   
     
     
         10 . The delivery system of  claim 9 , wherein said heater has a tubular shape. 
     
     
         11 . The delivery system of  claim 9 , further comprising a structural coil having a helical shape and being disposed around said heater and said tether. 
     
     
         12 . The delivery system of  claim 9 , wherein a distal and proximal end of said coil are fixed to said pusher, forming a loop engaged with said implant. 
     
     
         13 . The delivery system of  claim 9 , further comprising a support mandrel having a distal end fixed to said heater. 
     
     
         14 . The delivery system of  claim 9 , wherein said tether also extends adjacent to said heater, outside of said lumen. 
     
     
         15 . The delivery system of  claim 9 , wherein said implant is a stent having a plurality of cells and wherein said tether is located through at least some of said plurality of cells. 
     
     
         16 . The delivery system of  claim 15 , wherein said tether maintains said stent in a compressed configuration. 
     
     
         17 . An implant delivery system comprising:
 an elongated pusher comprising a tubular support structure, a heater fixed within the support structure, and a tether connected to the elongated pusher and positioned through an internal passage of said heater;   wherein, said heater comprises a helical coil having a first length formed to a first diameter and a second length formed to a second diameter that is smaller than said first diameter.   
     
     
         18 . The implant delivery system of  claim 17 , wherein said second length is located at a distal end of said heater. 
     
     
         19 . The implant delivery system of  claim 17 , wherein said tether has an external diameter of about 0.004 inch, said first diameter is about 0.007 inch, and said second diameter is about 0.005 inch. 
     
     
         20 . The implant delivery system of  claim 17 , wherein an outer surface of said heater is fixed to a support mandrel.