Method and apparatus for arrhythmia detection in a medical device

Abstract

A method and device for detecting arrhythmias in a patient that includes electrodes positioned subcutaneously within the patient, a microprocessor, coupled to the electrodes, determining one of a sequence of the sensing of cardiac signals by the electrodes and a duration between the sensing of cardiac signals by the electrodes, and control circuitry delivering a therapy in response to one of the determined sequence and the determined duration.

What is claimed is: 
     
         1 . A medical device for detecting arrhythmias in a patient, comprising:
 a plurality of electrodes positioned subcutaneously within the patient;   a microprocessor, coupled to the plurality of electrodes, determining one of a sequence of the sensing of cardiac signals by the plurality of electrodes and a duration between the sensing of cardiac signals by the plurality of electrodes; and   control circuitry delivering a therapy in response to one of the determined sequence and the determined duration.   
     
     
         2 . The device of  claim 1 , wherein the microprocessor determines occurrences of variations in a first sequence of moments of activation associated with a first electrode of the plurality of electrodes and a second sequence of moments of activation associated with a second electrode of the plurality of electrodes, and occurrences of differences in durations associated with the first moments of activation and the second moments of activation, and wherein the control circuitry delivers a first therapy in response to the determined occurrences of sequence variations and a second therapy in response to the determined occurrence of both sequence variations and differences in durations. 
     
     
         3 . The device of  claim 1 , wherein the control circuitry delivers a pacing pulse between a first electrode of the plurality of electrodes and a second electrode of the plurality of electrodes, and the microprocessor determines an evoked response to the pacing pulse via a third electrode of the plurality of electrodes, and confirms the presence of an event in response to the determined evoked response. 
     
     
         4 . The device of  claim 1 , wherein the microprocessor determines whether the sequence and the duration are substantially consistent. 
     
     
         5 . The device of  claim 1 , wherein the microprocessor compares a change in the duration between sensed signals to a predetermined threshold, and the control circuitry withholds the delivery of the therapy in response to the comparing. 
     
     
         6 . The device of  claim 1 , wherein the microprocessor determines a relative detection time corresponding to the sensing of cardiac signals. 
     
     
         7 . The device of  claim 1 , wherein the microprocessor identifies a first electrode of the plurality of electrodes to detect the signals as a reference electrode, determines relative values corresponding to detection of the signals by a second electrode of the plurality of electrodes to detect the signal and a third electrode of the plurality of electrodes to detect the signals relative to the reference electrode, and generates a detection duration corresponding to the signals in response to the determined relative values. 
     
     
         8 . The device of  claim 1 , further comprising a patch providing a common substrate integrating the plurality of electrodes thereon. 
     
     
         9 . The device of  claim 1 , wherein propagation of the cardiac signals is sensed locally. 
     
     
         10 . A method of detecting arrhythmias in a medical device, comprising:
 sensing cardiac signals via a plurality of electrodes positioned subcutaneously within a patient;   determining one of a sequence of the sensing of cardiac signals by the plurality of electrodes and a duration between the sensing of cardiac signals by the plurality of electrodes; and   delivering a therapy in response to one of the determined sequence and the determined duration.   
     
     
         11 . The method of  claim 10 , further comprising:
 generating a template corresponding to one of a sequence and a duration associated with a predetermined rhythm; and   comparing the determined one of a sequence of the sensing of cardiac signals by the first electrode and the second electrode and a duration between the sensing of cardiac signals by the first electrode and the second electrode to the generated template, wherein the therapy is delivered in response to the comparing.   
     
     
         12 . The method of  claim 10 , wherein the determining comprises determining occurrences in variation of a first sequence of moments of activation associated with a first electrode of the plurality of electrodes and a second sequence of moments of activation associated with a second electrode of the plurality of electrodes, and occurrences of differences in durations associated with the first moments of activation and the second moments of activation, and wherein delivering a therapy comprises delivering a first therapy in response to the determined occurrences of sequence variations and a second therapy in response to the determined occurrence of both sequence variations and differences in durations. 
     
     
         13 . The method of  claim 10 , further comprising:
 delivering a pacing pulse between a first electrode of the plurality of electrodes and a second electrode of the plurality of electrodes;   determining an evoked response via a third electrode of the plurality of electrodes; and   confirming the presence of an event in response to the determining of an evoked response.   
     
     
         14 . The method of  claim 13 , further comprising determining whether the sequence and the duration are substantially consistent. 
     
     
         15 . The method of  claim 10 , further comprising:
 comparing a change in the duration between sensed signals to a predetermined threshold; and   withholding the delivery of the therapy in response to the comparing.   
     
     
         16 . The method of  claim 15 , further comprising determining a relative detection time corresponding to sensing of the signals. 
     
     
         17 . The method of  claim 16 , wherein comparing a change in the duration comprises:
 identifying a first electrode of the plurality of electrodes to detect the signals as a reference electrode;   determining relative values corresponding to detection of the signals by a second electrode of the plurality of electrodes to detect the signal and a third electrode of the plurality of electrodes to detect the signals relative to the reference electrode; and   generating a detection duration corresponding to the signals in response to the determined relative values.   
     
     
         18 . The method of  claim 10 , wherein propagation of the cardiac signals is sensed locally. 
     
     
         19 . A computer readable medium having computer executable instructions for performing a method of detecting arrhythmias in a medical device comprising:
 sensing cardiac signals via a plurality of electrodes positioned subcutaneously within a patient;   determining one of a sequence of the sensing of cardiac signals by the plurality of electrodes and a duration between the sensing of cardiac signals by the plurality of electrodes; and   delivering a therapy in response to one of the determined sequence and the determined duration.