Delivery and detachment systems and methods for vascular implants
A system for delivering an implant device to a vascular site in a patient a delivery pusher apparatus, an implant device detachably connected to the delivery pusher apparatus by a tether having a distal end connected to a proximal end of the implant device, wherein the tether is substantially non-tensioned when connecting the implant device to the delivery pusher, and an electrical heating element configured coaxially around at least a portion of the tether, wherein heat generated by the heating element severs the tether at a point near the proximal end of the implant device.
1. An implant delivery system comprising:
an elongate delivery device having a proximal end and a distal end;
an implant device having a proximal end and a distal end and detachably connected to the delivery device by a tether, the proximal end of the implant adjacent the distal end of the elongate delivery device, wherein the tether is substantially non-tensioned;
an electric heater arranged coaxially around at least a portion of the tether, the electric heater comprising a distal winding portion contained substantially at the distal end of the elongate delivery device and providing a focused heating zone;
wherein the electric heater is operable to achieve a temperature in the distal winding portion that is sufficient to sever the tether; and,
wherein the distal winding portion is doubled back or reversed upon itself.
2. The implant delivery system of claim 1 , wherein the tether comprises a distal end coupled to the proximal end of the implant device.
3. The implant delivery system of claim 1 , wherein the distal winding portion has a pitch that is between about 0.018 mm and about 0.38 mm.
4. The implant delivery system of claim 1 , wherein the distal winding portion has between 2 and 10 coil windings.
5. The implant delivery system of claim 4 , wherein the distal winding portion has between 2 and 5 coil windings.
6. The implant delivery system of claim 1 , wherein the distal winding portion has a length that is between 0.1 mm and 0.5 mm.
7. The implant delivery system of claim 1 , wherein the tether comprises a polymeric material.
8. The implant delivery system of claim 1 , wherein the tether comprises a monofilament.
9. The implant delivery system of claim 1 , wherein the tether has a diameter or thickness of between about 0.05 mm and 0.2 mm.
10. The implant delivery system of claim 1 , wherein the tether is configured to withstand a tensile load of between 0.5 kg and 5 kg.
11. The implant delivery system of claim 1 , wherein the tether comprises polyester.
12. The implant delivery system of claim 1 , wherein the implant device includes a braided vascular occlusion device.
13. The implant delivery system of claim 1 , wherein the electric heater has a first resistance and is connectable to a power source by a pair of lead wires having a second resistance, and wherein the ratio of the first resistance to the second resistance is between 0.6 and 1.6.
14. The implant delivery system of claim 1 , wherein the tether has a distal portion and a proximal portion, and wherein the electric heater is disposed coaxially around the distal portion of the tether.
15. The implant delivery system of claim 14 , wherein the distal portion of the tether is connected to a proximal end of the implant device.
16. The implant delivery system of claim 1 , wherein the electric heater comprises a wire formed of a platinum-tungsten alloy.
17. The implant delivery system of claim 1 , further comprising an insulating tubing extending over the electric heater.
18. The implant delivery system of claim 17 , wherein a chamber is defined between the electric heater and the tether, the chamber being configured to resist the entrance of fluid.
19. The implant delivery system of claim 1 , wherein the electric heater comprises wire having a coating.
20. The implant delivery system of claim 19 , wherein the coating comprises an insulative material.
21. The implant delivery system of claim 20 , wherein the insulative material comprises polyimide.
22. The implant delivery system of claim 1 , wherein the electric heater further comprises a first open-pitch winding portion and a second open pitch winding portion, each extending proximally from the distal winding portion.
23. An implant delivery system comprising:
an elongate delivery device having a proximal end and a distal end;
an implant device having a proximal end and a distal end and detachably connected to the delivery device by a tether, the proximal end of the implant adjacent the distal end of the elongate delivery device, wherein the tether is substantially non-tensioned;
an electric heater arranged coaxially around at least a portion of the tether, the electric heater comprising a distal winding portion contained substantially at the distal end of the elongate delivery device and providing a focused heating zone;
wherein the electric heater is operable to achieve a temperature in the distal winding portion that is sufficient to sever the tether; and,
wherein the electric heater further comprises a first open-pitch winding portion and a second open pitch winding portion, each extending proximally from the distal winding portion.
24. The implant delivery system of claim 23 , wherein the tether comprises a distal end coupled to the proximal end of the implant device.
25. The implant delivery system of claim 23 , wherein the distal winding portion has a pitch that is between about 0.018 mm and about 0.38 mm.
26. The implant delivery system of claim 23 , wherein the distal winding portion has between 2 and 10 coil windings.
27. The implant delivery system of claim 26 , wherein the distal winding portion has between 2 and 5 coil windings.
28. The implant delivery system of claim 23 , wherein the distal winding portion has a length that is between 0.1 mm and 0.5 mm.
29. The implant delivery system of claim 23 , wherein the tether comprises a polymeric material.
30. The implant delivery system of claim 23 , wherein the tether comprises a monofilament.
31. The implant delivery system of claim 23 , wherein the tether has a diameter or thickness of between about 0.05 mm and 0.2 mm.
32. The implant delivery system of claim 23 , wherein the tether is configured to withstand a tensile load of between 0.5 kg and 5 kg.
33. The implant delivery system of claim 23 , wherein the tether comprises polyester.
34. The implant delivery system of claim 23 , wherein the implant device includes a braided vascular occlusion device.
35. The implant delivery system of claim 23 , wherein the electric heater has a first resistance and is connectable to a power source by a pair of lead wires having a second resistance, and wherein the ratio of the first resistance to the second resistance is between 0.6 and 1.6.
36. The implant delivery system of claim 23 , wherein the tether has a distal portion and a proximal portion, and wherein the electric heater is disposed coaxially around the distal portion of the tether.
37. The implant delivery system of claim 36 , wherein the distal portion of the tether is connected to a proximal end of the implant device.
38. The implant delivery system of claim 23 , wherein the electric heater comprises a wire formed of a platinum-tungsten alloy.
39. The implant delivery system of claim 23 , further comprising an insulating tubing extending over the electric heater.
40. The implant delivery system of claim 39 , wherein a chamber is defined between the electric heater and the tether, the chamber being configured to resist the entrance of fluid.
41. The implant delivery system of claim 23 , wherein the electric heater comprises wire having a coating.
42. The implant delivery system of claim 41 , wherein the coating comprises an insulative material.
43. The implant delivery system of claim 42 , wherein the insulative material comprises polyimide.
44. The implant delivery system of claim 23 , wherein the distal winding portion is doubled back or reversed upon itself.