Electrode displacement determination

Abstract

Methods and systems for determining whether a location of multiple current injecting electrodes has changed are disclosed herein.

1 .- 15 . (canceled) 
     
     
         16 . A system comprising:
 one or more measuring electrodes positioned at one or more secure locations;   multiple current injecting electrodes at least some of the current injecting electrodes being placed in stable locations inside a patient's body to generate a field in an organ;   an electronic control system coupled to the multiple current injecting electrodes and to the one or more measuring electrodes and configured to:
 cause current to flow among multiple current injecting electrodes; 
   in response to the current flow, measure a signal at the one or more measuring electrodes;   a processing system coupled to the electronic system and configured to:
 generate a baseline signal measurement; 
 subsequent to generation of the baseline signal measurement, compare a measured signal from the one or more measuring electrodes to the baseline signal to generate a comparison result; and 
 determine whether a location of the multiple current injecting electrodes inside the patient's body has changed based on the comparison result. 
   
     
     
         17 . The system of  claim 16 , further comprising an indicator configured to provide an audio or visual indication upon determining that the location of the multiple current injecting electrodes has changed. 
     
     
         18 . The system of  claim 16 , wherein the one or more measuring electrodes comprise one or more ECG leads. 
     
     
         19 . The system of  claim 16 , wherein the one or more measuring electrodes comprise one or more body surface electrodes. 
     
     
         20 . The system of  claim 16 , wherein the system further comprises multiple measuring electrodes on a catheter and wherein:
 the electronic control system is further configured to measure a signal at each of multiple measuring electrodes on the catheter for each of multiple locations of the catheter; and   the processing system is further configured to determine expected signals for the measuring electrodes at additional locations within the organ based on the measured signals.   
     
     
         21 . The system of  claim 20 , wherein the processing system is further configured to determine a relative location of another catheter based on the signals measured by the multiple measuring electrodes on the catheter. 
     
     
         22 . The method of  claim 16 , wherein the one or more measuring electrodes comprise one or more stable intracardiac electrodes. 
     
     
         23 . The system of  claim 20 , wherein the processing system is further configured to compensate for respiration and heartbeat. 
     
     
         24 . The system of  claim 20 , wherein the processing system is further configured to compare the measured field to the baseline signal using a residual norm between the baseline signal and the measured signal. 
     
     
         25 . The system of  claim 24 , wherein the processing system is further configured to compare the measured field to the baseline signal by comparing the residual norm to a threshold value. 
     
     
         26 . The system of  claim 16 , further comprising a display unit configured to provide information to enable a clinician to guide the current injecting electrodes to a location where the baseline signal measurement was generated. 
     
     
         27 . The system of  claim 16 , further comprising a display unit configured to display a displacement trajectory. 
     
     
         28 . The method of  claim 27 , wherein the displacement trajectory provides a three-dimensional model providing an indication of a current location of the current injecting electrodes and an indication of the location where the baseline signal measurement was generated.