System And Method For Locating Detachment Zone Of A Detachable Implant

Abstract

A system and method for quickly detaching an implant and for locating the detachment zone of a detachable implant. A sensor determines a sudden change in the local environment as the sensor passes from within a microcatheter to being exposed to the vasculature. The sensor may be a temperature sensor, ultrasonic sensor, pressure sensor or the like. If the detachable implant assembly uses a heater coil to detach the implant, the heater coil may be used as a sensor. Additionally, the implant itself may be used as a sensor if a change in electrical resistance is detectable as the implant exits the microcatheter and changes shape.

What is claimed is: 
     
         1 . A system for determining when an implant has advanced out of a catheter comprising:
 a catheter having a lumen and a distal end;   a pusher disposed within the lumen of the catheter;   an implant advanceable through the lumen by the pusher; and   a sensor system having a sensor located along a distal portion of the pusher and disposed proximate the implant; the sensor system calibrated to determine and signal when the implant has advanced completely out of the distal end of the catheter;   wherein the sensor system includes a proximal voltage source with a positive terminal and a negative terminal, and a circuit is formed between the sensor and the positive and the negative terminals of the proximal voltage source to power the sensor.   
     
     
         2 . The system of  claim 1 , further comprising electrical wires providing electrical communication between the positive and negative terminals of the proximal voltage source and the sensor. 
     
     
         3 . The system of  claim 2 , wherein the electrical wires are disposed in the pusher. 
     
     
         4 . The system of  claim 1 , wherein the sensor is located on a detachment zone which detaches from the implant to release the implant from the pusher. 
     
     
         5 . The system of  claim 4 , wherein the detachment zone is a resistance-type heater coil. 
     
     
         6 . The system of  claim 1 , wherein the sensor system is located within the catheter. 
     
     
         7 . The system of  claim 1 , further comprising one or more electrical wires providing electrical communication between the sensor and a proximal human interface. 
     
     
         8 . The system of  claim 1 , wherein the proximal voltage source is a DC battery. 
     
     
         9 . A system for determining when an implant has advanced out of a catheter comprising:
 a catheter having a lumen and a distal end;   a pusher disposed within the lumen of the catheter;   an implant advanceable through the lumen by the pusher; and   a sensor system having a sensor located proximally adjacent the implant; the sensor system calibrated to determine and signal when the implant has advanced completely out of the distal end of the catheter;   wherein the sensor system includes a proximal voltage source with a positive terminal and a negative terminal, and a circuit is formed between the sensor and the positive and the negative terminals of the proximal voltage source to power the sensor.   
     
     
         10 . The system of  claim 9 , further comprising a detachment system to detach the implant, where the detachment system includes a proximal voltage source having a positive terminal and a negative terminal. 
     
     
         11 . The system of  claim 10 , wherein the detachment system and sensor system utilize the same proximal voltage source. 
     
     
         12 . The system of  claim 10  further comprising a first wire connected to the positive terminal of the proximal voltage source and a second wire connected to the negative terminal of the proximal voltage source, where the first and second wires are distally connected to a detachment interface. 
     
     
         13 . The system of  claim 10 , wherein the detachment interface is a resistance-type heater coil. 
     
     
         14 . A system for determining when an implant has advanced out of a catheter comprising:
 a catheter having a lumen and a distal end;   a pusher disposed within the lumen of the catheter;   an implant advanceable through the lumen by the pusher; and   a sensor system having a sensor located proximal to the implant along a distal portion of the pusher; the sensor system calibrated to determine and signal when the implant has advanced completely out of the distal end of the catheter;   wherein the sensor system includes a proximal voltage source with a positive terminal and a negative terminal, and a circuit is formed between the sensor and the positive and the negative terminals of the proximal voltage source to power the sensor.   
     
     
         15 . The system of  claim 14 , wherein the sensor is a resistance-type heater coil. 
     
     
         16 . The system of  claim 14 , wherein the sensor is a temperature sensor, and the sensor system utilizes an increase in detected temperature to determine that the implant has advanced completely out of the distal end of the catheter. 
     
     
         17 . The system of  claim 14 , wherein the sensor is a pressure sensor, and the sensor system utilizes a change in detected pressure from a static reading to a dynamic reading to determine that the implant has advanced completely out of the distal end of the catheter. 
     
     
         18 . The system of  claim 14 , wherein the sensor system utilizes a detected ultrasound differential to determine that the implant has been advanced completely out of the distal end of the catheter. 
     
     
         19 . The system of  claim 14 , wherein the sensor system utilizes a change in detected resistance as the implant changes from a straight configuration when within the catheter to a coiled configuration when pushed distally beyond the catheter to determine that the implant has been advanced completely out of the distal end of the catheter. 
     
     
         20 . The system of  claim 14 , wherein the implant is an embolic coil having a straight configuration when within the catheter and a coiled configuration when pushed distally beyond the catheter.