Detection and localization of cardiac fast firing

Abstract

Systems and methods for cardiac fast firing (e.g., atrial fast firing) detection perform frequency analysis on channels of collected cardiac waveform data and test the data for outlier frequency complex content that is of higher frequency than baseline frequency complex content associated with cardiac fibrillation (e.g., atrial fibrillation) or other arrhythmogenic activity. Anatomical regions from whence the cardiac fast firing originates can be displayed in real time on an epicardial surface map via a graphical display, aiding administration of therapy. Prior to such detection, QRST complex removal can be performed to ensure that ventricular activity does not infect the atrial fast firing analysis. A frequency-based method for QRST complex removal is also disclosed.

1 . A system comprising:
 non-transitory memory configured to store machine-readable instructions and data, the data including electrophysiological data representing electrocardiogram (ECG) signals for a plurality of locations across a cardiac surface; and   a processor to access the non-transitory memory and execute the machine-readable instructions, the instructions comprising:
 cardiac fast firing detection code programmed to perform cardiac fast firing detection to identify a subset of the ECG signals exhibiting outlier frequency activity having a dominant frequency that is higher than a dominant frequency determined for baseline fibrillation activity; and 
 code programmed to store in the memory cardiac fast firing data characterizing the detected fast firing. 
   
     
     
         2 . The system of  claim 1 , wherein the cardiac fast firing data is provided to specify times, channels, and/or epicardial surface regions exhibiting cardiac fast firing. 
     
     
         3 . The system of  claim 1 , wherein the instructions further comprise:
 code to convert the plurality of ECG signals into frequency-domain ECG signals; and   code programmed to remove ventricular content from the frequency-domain ECG signals, the cardiac fast firing detection code operating on the plurality of ECG signals following removal of the ventricular content.   
     
     
         4 . The system of  claim 1 , wherein the instructions further comprise code to map the subset of the ECG signals identified as fast-firing to one or more spatial locations of a heart and store map data representative thereof. 
     
     
         5 . The system of  claim 4 , further comprising a display, the instructions providing output data that includes a graphical representation to visualize the one or more spatial locations of the heart exhibiting fast-firing. 
     
     
         6 . The system of  claim 1 , wherein the cardiac fast firing detection code is further programmed to:
 compare dominant frequencies of respective ECG signals from the among the plurality of ECG signals relative to a frequency threshold, the frequency threshold being between the dominant frequency of the outlier frequency activity and the dominant frequency of the baseline fibrillation activity; and   identify the subset of ECG signals from among the plurality of ECG signals to be representative of a fast-firing event based on the comparison.   
     
     
         7 . The system of  claim 6 , wherein the cardiac fast firing detection code is further programmed to determine the fast-firing event has occurred based on a number of channels, corresponding to the subset of ECG signals identified as being fast-firing, exceeding a channel number threshold. 
     
     
         8 . The system of  claim 1 , wherein the plurality of ECG signals are provided via a respective plurality of channels, and the cardiac fast firing detection code is further programmed to:
 analyze frequency data of each of the plurality of channels from among the plurality of ECG signals over a number of time intervals; and   identify one or more of the plurality of channels as a fast-firing channel during at least one of the time intervals based on the identified channel showing substantial movement in dominant frequency from a lower-frequency range to a higher-frequency range, or from the higher-frequency range to the lower-frequency range.   
     
     
         9 . The system of  claim 1 , wherein the cardiac fast firing detection code is further programmed to:
 compare frequency data of an ECG signal for a given spatial location on the cardiac surface from among the plurality of ECG signals to frequency data of ECG signals for one or more spatially neighboring locations on the cardiac surface during a time interval; and   identify the subset of ECG signals from among the plurality of ECG signals to be representative of a fast-firing event based on the comparison.   
     
     
         10 . The system of  claim 1 , wherein the cardiac fast firing detection code is further programmed to:
 generate a composite frequency analysis signal based on frequency analyses of the plurality of ECG signals, corresponding to different spatial locations of the cardiac surface, during a time interval;   identify the subset of ECG signals from among the plurality of ECG signals to be representative of a fast-firing event based on determining that the composite frequency analysis signal exhibits a bimodal distribution during one part of the time interval and a unimodal distribution during another part of the time interval.   
     
     
         11 . The system of  claim 1 , further comprising a therapy system to control delivery of a therapy based on the cardiac fast firing data. 
     
     
         12 . The system of  claim 1 , wherein the ECG signals are acquired based on electrical measurements performed invasively and/or non-invasively. 
     
     
         13 . The system of  claim 1 , wherein the instructions further comprise code programmed to localize the detected fast firing to one or more spatial regions of a heart based on the cardiac fast firing data. 
     
     
         14 . The system of  claim 1 , wherein the cardiac fast firing detection code is programmed to determine respective outlier dominant frequencies for a set of channels exhibiting a frequency that is at least one standard deviation greater than a mean of the baseline fibrillation activity. 
     
     
         15 . The system of  claim 1 , wherein the plurality of ECG signals are provided via a respective plurality of channels, and the instructions further comprise code programmed to removing QRST content from the ECG signals provided by each of the plurality of channels. 
     
     
         16 . The system of  claim 15 , wherein the code programmed to removing QRST content QRST content further comprises:
 code programmed to perform frequency analysis on an electrocardiographic signal derived from one of the plurality of channels to generate signal frequency plot data;   code programmed to perform frequency analysis on an identified QRST frequency template to generate template frequency plot data;   code programmed to subtract the template frequency plot data from the signal frequency plot data to generate frequency plot data of a QRST-removed electrocardiographic signal corresponding to the electrocardiographic signal; and   wherein the signal frequency plot data generation and the subtraction is repeated for additional channels in the plurality of channels.   
     
     
         17 . A system comprising:
 non-transitory memory configured to store machine-readable instructions and data, the data including cardiac waveform data representative of electrophysiological signals provided via a plurality of channels;   a processor configured to access the memory and execute the machine-readable instructions, the instructions programmed to at least:
 perform a frequency analysis on a respective electrocardiographic signal derived from one of a plurality of electrocardiographic channels to generate signal frequency plot data; 
 perform a frequency analysis on an identified QRST frequency template to generate template frequency plot data; 
 subtract the template frequency plot data from the signal frequency plot data to generate frequency data of a QRST-removed electrocardiographic signal corresponding to the respective electrocardiographic signal; and 
 repeat the signal frequency plot data generation and the subtraction for additional channels in the plurality of electrocardiographic channels to provide respective QRST-removed electrocardiographic signals for the plurality of channels. 
   
     
     
         18 . The system of  claim 17 , wherein an amount of power removed from the electrocardiographic signal in the QRST-removed electrocardiographic signal is based on a provided number of QRS complexes in the electrocardiographic signal, and wherein the template frequency plot data is not normalized. 
     
     
         19 . The system of  claim 17 , wherein the instructions are further programmed to:
 perform a second frequency analysis on the respective QRST-removed electrocardiographic signals for the plurality of channels;   perform cardiac fast firing detection to identify a subset of the channels exhibiting outlier frequency activity having a dominant frequency that is higher than a dominant frequency determined for baseline fibrillation activity;   map the subset of the ECG signals identified as fast-firing to one or more spatial locations of a heart; and   display a graphical representation to visualize the one or more spatial locations of the heart exhibiting fast-firing.   
     
     
         20 . The system of  claim 19 , further comprising a therapy system to control delivery of a therapy based on the cardiac fast firing data.