Fast-detaching electrically insulated implant

Abstract

This is an implant for placement in the human body and an assembly for so placing that implant. Most desirably, it is an implant for use in the vasculature of the human body and is used to occlude some space in that vasculature as a portion of a treatment regimen. The implant itself is preferably a component of a deployment device using an electrolytically severable joint. The implant component is at least partially covered with a highly resistive or insulative covering. The highly resistive or insulative layer or covering appears to enhance the susceptibility of the electrolytic joint to quick erosion and thus detachment of the implant. Although the implant itself is preferably a vaso-occlusive device, it may instead be a stent, a vena cava filter, or other implant which may be installed in this manner. The implant may be independently coated with insulative or resistive material or may be formed using a material with such as tantalum, which forms such an insulator or resistor in situ.

We claim the following: 
     
       1. A method for introducing an implant member into a selected space within the human body comprising:
 placing an implant member via an attached core wire into the selected space, said implant member having a proximal end and a distal end and having an implant member core at least partially covered with an inorganic insulative covering comprising platinum, the implant member core being substantially covered with one of tantalum or zirconium, wherein the implant member further comprises an electrolytically severable joint attached to the implant member proximal end, the joint being relatively more susceptible to electrolysis in an ionic solution than is the implant member, and 
 electrolytically detaching the implant member from the core wire. 
 
     
     
       2. The method of  claim 1  wherein the implant member further comprises an electrolytically severable joint attached to the implant member proximal end, the joint being relatively more susceptible to electrolysis in an ionic solution than is the implant member, and the step of detaching the implant from the core wire is accomplished electrolytically. 
     
     
       3. The method of  claim 1  wherein the implant member at least partially comprises an oxide-forming material. 
     
     
       4. The method of  claim 1  wherein the implant member comprises a core at least partially covered by a oxide-forming member. 
     
     
       5. The method of claim  2  wherein the implant member comprises a core at least partially covered by an oxide-forming material 1, wherein at least 95% of the surface area of the implant member is covered with one of tantalum or zirconium. 
     
     
       6. The method of  claim 1  wherein the implant member comprises a stent. 
     
     
       7. The method of  claim 1  wherein the implant member comprises a vena cava filter. 
     
     
       8. The method of  claim 1  wherein the implant member comprises a helically wound coil. 
     
     
       9. The method of  claim 8  wherein the coil further comprises a stretch resistant member extending at least partially from a proximal end of the coil to a distal end of the coil. 
     
     
       10. The method of  claim 9  wherein the stretch resistant member comprises polypropylene. 
     
     
       11. The method member of  claim 1  wherein the implant member comprises a braid. 
     
     
       12. A method for occluding a selected space within a human body comprising:
 placing the a tip of a catheter near the selected space, 
 introducing into a lumen of said catheter a tantalum an occluding member having a proximal end and a distal end and including an inner core comprising platinum, the inner core being substantially covered with one of tantalum or zirconium and further comprising an electrolytically severable joint attached to the occluding member proximal end, the joint being relatively more susceptible to electrolysis in an ionic solution than is the occluding member, 
 placing the occluding member into the space through the catheter tip, and 
 electrolytically severing the joint. 
 
     
     
       13. The method of  claim 12  wherein the occluding member is at least partially covered with tantalum oxide. 
     
     
       14. The method of  claim 12  wherein the occluding member comprises a coil. 
     
     
       15. The method of  claim 14  wherein the coil further comprises a stretch resistant member extending at least partially from a proximal end of the coil to a distal end of a coil. 
     
     
       16. The method of  claim 12  wherein the occluding member comprises a braid. 
     
     
       17. A method for occluding an aneurysm comprising:
 placing the a tip of a catheter near the aneurysm via a blood vessel, 
 introducing into a lumen of the catheter a vaso-occlusive coil having a proximal end and a distal end and a highly resistive or insulative layer on at least a portion of the coil, the coil including an inner core comprising platinum, the inner core being substantially covered with one of tantalum and zirconium, the coil further comprising a sacrificial link attached to the coil proximal end, the link being relatively more susceptible to electrolysis in an ionic solution than is the coil, said link connected to a core wire, 
 advancing the coil through the catheter lumen, out the catheter tip and into the aneurysm, applying a positive electric current to the core wire to dissolve the link,; and 
 removing the core wire and catheter from the vessel. 
 
     
     
       18. The method of  claim 17  wherein the coil comprises tantalum. 
     
     
       19. The method of  claim 18  wherein the coil is at least partially covered with tantalum oxide. 
     
     
       20. The method of  claim 17  wherein the core wire comprises platinum. 
     
     
       21. A method for introducing an implant member into a selected space within the human body comprising:
 placing an implant member via an attached core wire into the selected space, the core wire having a distal end comprising an electrolytically severable joint, said implant member comprising a proximal end and a distal end and a core formed from platinum, the core being substantially covered with one of tantalum and zirconium;   applying an electrical current to the core wire, wherein said current transforms the one of tantalum and zirconium into an insulative oxide in situ on an exterior surface of the implant member; and   detaching the implant member from the core wire at the electrolytically severable joint.   
     
     
       22. The method of claim 21 wherein the implant member comprises a stent. 
     
     
       23. The method of claim 21 wherein the implant member comprises a vena cava filter. 
     
     
       24. The method of claim 21 wherein the implant member comprises a helically wound coil. 
     
     
       25. The method of claim 24 wherein the coil further comprises a stretch resistant member extending at least partially from a proximal end of the coil to a distal end of the coil. 
     
     
       26. The method of claim 25 wherein the stretch resistant member comprises polypropylene. 
     
     
       27. The method of claim 21 wherein the implant member comprises a braid.