Patent ID: 8577455

Claim:
A medical device adapted to detect arrythmias in a patient having a thoracic cavity containing a heart generating a cardiac signal comprising a plurality of cardiac events, comprising: a plurality of electrodes positionable subcutaneously within the patient and outside of the thoracic cavity sensing the cardiac signal; a microprocessor, coupled to the plurality of electrodes: identifying a plurality of sequences by which individual ones of the plurality of electrodes sense individual ones of the plurality of cardiac events; identifying a plurality of durations comprising time between moments of activation of one of the plurality of electrodes and moments of activation associated with another of said plurality of electrodes; determining occurrences of sequence 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 determining occurrences of differences in the durations associated with the moments of activation of the first sequence and the moments of activation of the second sequence, and control circuitry delivering a first therapy in response to the occurrences of sequence variations and a second therapy in response to an occurrence of both sequence variations and differences in durations.