Method for detecting pocket stability for an implantable cardiac monitor

Abstract

A computer implemented method for detecting pocket stability for an implantable cardiac monitor, including under control of one or more processors in the ICM, collecting impedance data over at least one cardiac cycle. The impedance data is processed to separate an impedance waveform that varies over the at least one cardiac cycle in a manner representative of cardiac functionality over the at least one cardiac cycle. A characteristic of interest is analyzed from the impedance waveform over the at least one cardiac cycle. A pocket stability state of the ICM is identified and recorded based on the analyzing operation.

What is claimed is: 
     
         1 . A computer implemented method for detecting pocket stability for an implantable cardiac monitor (ICM), the method comprising:
 under control of one or more processors,   forming a base-line impedance waveform and base-line pocket stability state based on historical data;   collecting impedance data from an alternating current (AC) signal over at least one cardiac cycle;   processing the impedance data to separate an impedance waveform from at least one cardiac cycle in a manner representative of cardiac functionality over the at least one cardiac cycle;   analyzing a characteristic of interest from the impedance waveform over the at least one cardiac cycle to determine a pocket stability state; and   after determining the pocket stability state, comparing the pocket stability state based on the historical data and the pocket stability state determined from the processed impedance waveform to determine a change in pocket stability state.   
     
     
         2 . The method of  claim 1 , further comprising:
 recording electrocardiogram (EGM) signals at electrodes provided on a housing of the ICM;   detecting a pause or stoppage based on the recorded EGM signals;   determining whether the pause or stoppage is false by comparing a subsequent impedance waveform to the base-line impedance waveform; and   outputting an indicator signal that the ICM has shifted within an implant pocket and is experiencing degradation of signal quality of the EGM signals when the pause or stoppage is false.   
     
     
         3 . The method of  claim 1 , wherein analyzing the characteristic of interest from the impedance waveform over the at least one cardiac cycle to determine a pocket stability state comprises comparing the characteristic of interest from the processed impedance waveform and a characteristic of interest from historical data. 
     
     
         4 . The method of  claim 3 , wherein the characteristic of interest of the processed impedance waveform is at least one of impedance waveform, impedance waveform slope, impedance waveform amplitude, or impedance waveform peak-to-peak value. 
     
     
         5 . The method of  claim 4 , wherein the historical data includes impedance waveform morphology data. 
     
     
         6 . The method of  claim 1 , further comprising, outputting an indicator signal that the ICM has shifted within an implant pocket, wherein the indicator is an alert signal that provides a communication from the ICM related to the change in pocket stability state. 
     
     
         7 . A monitoring system for detecting pocket stability for an implantable cardiac monitor (ICM) within a subcutaneous pocket, comprising:
 an ICM including a housing and one or more processors for receiving impedance data generated by an alternating current (AC) signal of the ICM and configured to:
 form a base-line impedance waveform and base-line pocket stability state based on historical data; 
 collect impedance data from an alternating current (AC) signal over at least one cardiac cycle; 
 process the impedance data to separate an impedance waveform from at least one cardiac cycle in a manner representative of cardiac functionality over the at least one cardiac cycle; 
 analyze a characteristic of interest from the impedance waveform over the at least one cardiac cycle to determine a pocket stability state; and 
 after determining the pocket stability state, compare the pocket stability state based on the historical data and the pocket stability state determined from the processed impedance waveform to determine a change in pocket stability state. 
   
     
     
         8 . The system of  claim 7 , wherein the one or more processors are further configured to:
 record electrocardiogram (EGM) signals at electrodes provided on a housing of the ICM;   detect a pause or stoppage based on the recorded EGM signals;   determine whether the pause or stoppage is false by comparing a subsequent impedance waveform to the base-line impedance waveform; and   output an indicator signal that the ICM has shifted within an implant pocket and is experiencing degradation of signal quality of the EGM signals when the pause or stoppage is false.   
     
     
         9 . The system of  claim 7 , wherein analyzing the characteristic of interest from the impedance waveform over the at least one cardiac cycle to determine a pocket stability state comprises comparing the characteristic of interest from the processed impedance waveform and a characteristic of interest from historical data. 
     
     
         10 . The system of  claim 9 , wherein the characteristic of interest of the processed impedance waveform is at least one of impedance waveform, impedance waveform slope, impedance waveform amplitude, or impedance waveform peak-to-peak value. 
     
     
         11 . The system of  claim 9 , wherein the historical data includes impedance waveform morphology data. 
     
     
         12 . The system of  claim 7 , wherein the one or more processors are further configured to output an indicator signal that the ICM has shifted within an implant pocket, wherein the indicator is an alert signal that provides a communication from the ICM related to the change in pocket stability state.