Non-captured intrinsic discrimination in cardiac pacing response classification

Abstract

Cardiac devices and methods discriminate non-captured intrinsic beats during evoked response detection and classification by comparing the features of a post-pace cardiac signal with expected features associated with a non-captured response with intrinsic activation. Detection of a non-captured response with intrinsic activation may be based on the peak amplitude and timing of the cardiac signal. The methods may be used to discriminate between a fusion or capture beat and a non-captured intrinsic beat. Discriminating between possible cardiac responses to the pacing pulse may be useful, for example, during automatic capture verification and/or a capture threshold test.

1 . A method of classifying a cardiac response to a pacing pulse, comprising: 
 delivering the pacing pulse to a heart;    sensing a cardiac signal following delivery of the pacing pulse;    comparing one or more characteristics of the cardiac signal to one or more expected cardiac signal characteristics associated with a non-captured response with intrinsic activity; and    classifying the cardiac response to the pacing pulse as the noncaptured response with intrinsic activation based on the comparison.    
   
   
       2 . The method of  claim 1 , wherein comparing the cardiac signal characteristics to the expected characteristics comprises extracting features of the cardiac signal and comparing the features to expected cardiac signal features associated with the non-captured response with intrinsic activity.  
   
   
       3 . The method of  claim 2 , wherein comparing the one or more features of the cardiac signal to the one or more expected features associated with the non-captured response with intrinsic activation comprises determining if one or more peaks of the cardiac signal respectively fall within one or more intrinsic detection windows, each of the one or more intrinsic detection windows associated with an intrinsic peak amplitude range and an intrinsic peak timing interval.  
   
   
       4 . The method of  claim 1 , wherein classifying the cardiac response further comprises discriminating the non-captured response with intrinsic activation from unknown cardiac activity.  
   
   
       5 . The method of  claim 1 , wherein classifying the cardiac response further comprises discriminating between a captured response and the non-captured response with intrinsic activation.  
   
   
       6 . The method of  claim 5 , wherein discriminating between the captured response and the non-captured response with intrinsic activation comprises classifying the cardiac response as the captured response if one or more features of the cardiac signal are consistent with expected features associated with the captured response.  
   
   
       7 . The method of  claim 1 , wherein classifying the cardiac response further comprises discriminating the cardiac response as a fusion beat if the cardiac response does not comprise a captured beat or a non-captured intrinsic beat.  
   
   
       8 . The method of  claim 1 , wherein classifying the cardiac response to the pacing pulse comprises classifying the cardiac response to the pacing pulse during automatic capture verification.  
   
   
       9 . The method of  claim 1 , wherein classifying the cardiac response to the pacing pulse comprises classifying the cardiac response to the pacing pulse during a capture threshold test.  
   
   
       10 . The method of  claim 1 , further comprising: 
 sensing for a cardiac signal peak in at least two capture detection windows, each of the at least two capture detection windows associated with a captured response peak amplitude range and a captured response peak time interval; and    classifying the cardiac response as a captured response if the cardiac signal peaks are detected in the at least two capture detection windows.    
   
   
       11 . The method of  claim 10 , further comprising classifying the cardiac response as fusion if the cardiac response does not comprise a non-captured intrinsic response or a captured response.  
   
   
       12 . The method of  claim 1 , further comprising: 
 sensing for the cardiac signal peak in at least one noise detection window, the at least one noise detection window associated with a noise window amplitude range and a noise window time interval; and    classifying the cardiac response as unknown cardiac signal behavior if the cardiac signal peak is detected in the at least one noise detection window.    
   
   
       13 . A system for classifying a cardiac response to a pacing pulse, comprising: 
 a sensor system, comprising a plurality of electrodes electrically coupled to a heart, the sensor system configured to sense a cardiac signal following delivery of the pacing pulse; and    a processor coupled to the sensing system, the processor configured to compare one or more characteristics of the cardiac signal to one or more expected cardiac signal characteristics associated with a non-captured intrinsic beat, and to classify the cardiac response to the pacing pulse as the non-captured intrinsic beat based on the comparison.    
   
   
       14 . The system of  claim 13 , wherein the one or more characteristics of the cardiac signal comprise one or more features of the cardiac signal and the one or more expected characteristics comprise one or more expected characteristics and the processor is configured to extract the one or more features from the cardiac signal and to compare the extracted features to the one or more expected features.  
   
   
       15 . The system of  claim 14 , wherein the one or more extracted features comprises a peak time of the cardiac signal and the one or more expected features comprises an expected peak timing range.  
   
   
       16 . The system of  claim 14 , wherein the one or more extracted features comprises a peak amplitude of the cardiac signal and the one or more expected features comprises an expected peak amplitude range.  
   
   
       17 . The system of  claim 13 , wherein the processor is configured to discriminate the non-captured intrinsic beat from other cardiac activation based on the one or more characteristics of the cardiac signal.  
   
   
       18 . The system of  claim 13 , wherein the processor is configured to classify the cardiac response as the non-captured intrinsic beat if a cardiac signal peak is detected in at least one intrinsic detection window, the at least one intrinsic detection window associated with an intrinsic beat amplitude range and an intrinsic beat time interval relative to the cardiac signal.  
   
   
       19 . The system of  claim 18 , wherein parameters of the at least one intrinsic detection window are selected based on an expected timing of a cardiac signal feature associated with a captured response.  
   
   
       20 . The system of  claim 18 , wherein parameters of the at least one intrinsic detection window are selected based on patient conditions.  
   
   
       21 . A cardiac device, comprising: 
 a pulse generator configured to deliver a pacing pulse to a heart;    a sensing system configured to sense a cardiac signal following delivery of the pacing pulse;    means for comparing one or more features of the cardiac signal to one or more expected features associated with a non-captured response with intrinsic activation; and    means for classifying the cardiac response to the pacing pulse as the non-captured response with intrinsic activation based on the comparison.    
   
   
       22 . The cardiac device of  claim 21 , further comprising means for determining if a peak amplitude of the cardiac signal falls within an intrinsic detection window, the intrinsic detection window associated with an intrinsic peak amplitude range and an intrinsic peak timing interval.