Method and apparatus for arrhythmia detection in a medical device

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 sequence by which individual ones of the plurality of electrodes sense individual ones of the plurality of cardiac events;
• and
• a duration between sensing by individual ones of the plurality of electrodes of an individual one of the plurality of cardiac events of the cardiac signal;
• and
• control circuitry delivering a therapy in response to one of the sequence and the duration,
• wherein the microprocessor identifies a first electrode of the plurality of electrodes to detect individual ones of the plurality of cardiac events as a reference electrode, determines relative values corresponding to detection of individual ones of the plurality of cardiac events by a second electrode of the plurality of electrodes to detect the signal and a third electrode of the plurality of electrodes to detect individual ones of the plurality of cardiac events relative to the reference electrode, and generates a detection duration corresponding to the cardiac signal in response to the determined relative values.

A method of detecting arrhythmias in a medical device, comprising:

• sensing a cardiac signal comprising a plurality of cardiac events via a plurality of electrodes positioned within a patient and outside of a thoracic cavity of the patient;
• identifying a plurality of sequences of said cardiac signal;
• identifying a plurality of durations comprising time between moments of activation associated with one of the plurality of electrodes and moments of activation associated with another of the plurality of electrodes;
• determining occurrences of sequence variations 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
• determining occurrences of differences in the durations associated with the moments of activation a first one of the plurality of sequences and the moments of activation of a second one of the plurality of sequences, and
• delivering a therapy comprises delivering a first therapy in response to the occurrences of sequence variations and a second therapy in response to the occurrence of both sequence variations and differences in durations.

A method of detecting arrhythmias in a medical device, comprising:

• sensing a cardiac signal comprising a plurality of cardiac events via a plurality of electrodes positioned within a patient and outside of a thoracic cavity of the patient;
• identifying a sequence of said cardiac signal;
• identifying a duration between sensing by individual ones of the plurality of electrodes of an individual one of the plurality of cardiac events of the cardiac signal;
• and delivering a therapy in response to one of the sequence and the duration;
• comparing a change in the duration between cardiac events to a predetermined threshold by identifying a first electrode of the plurality of electrodes to detect the cardiac events as a reference electrode;
• withholding the delivery of the therapy in response to the comparing;
• determining a relative detection time corresponding to sensing of the cardiac events;
• determining relative values corresponding to detection of the signals by a second electrode of the plurality of electrodes to detect the cardiac events and a third electrode of the plurality of electrodes to detect the cardiac events relative to the reference electrode;
• and
• generating a detection duration corresponding to the cardiac events in response to the determined relative values.