Medical device and method for detecting arrhythmia

A method comprising:

• sensing a plurality of cardiac signals;
• sensing ventricular event signals from at least one of the plurality of cardiac signals;
• detecting a ventricular tachyarrhythmia based on the sensed plurality of cardiac signals;
• and
• subsequent to detecting the ventricular tachyarrhythmia:
• determining from the sensed ventricular event signals that a redetection number of tachyarrhythmia intervals is reached;
• determining when a first rejection rule for withholding a tachyarrhythmia detection is met based on an analysis of the plurality of cardiac signals;
• and
• withholding redetection of a ventricular tachyarrhythmia when the first rejection rule is met and the redetection number of tachyarrhythmia intervals is reached;
• and
• redetecting the ventricular tachyarrhythmia when the first rejection rule is not met and the redetection number of tachyarrhythmia intervals is reached.

A non-transitory, computer readable medium storing a set of instructions that, when executed by a control circuit of a medical device, cause the medical device to:

• sense a plurality of cardiac signals;
• sense ventricular event signals from the plurality of cardiac signals;
• for each of a plurality of sensed ventricular event signals, determine sensed event data from the plurality of cardiac signals;
• obtain a cardiac signal segment from the plurality of cardiac signals, the cardiac signal segment having a starting time that is independent of a timing of a ventricular event signal sensed by the sensing circuit;
• perform a morphology analysis of the cardiac signal segment for classifying the cardiac signal segment as being one of ventricular tachyarrhythmia, non-ventricular tachyarrhythmia or asystole;
• determine from the ventricular event signals that a required number of tachyarrhythmia intervals is reached for detecting ventricular tachyarrhythmia;
• determine that a rejection rule for withholding a tachyarrhythmia detection is met based on the sensed event data;
• determine that the cardiac signal segment is classified as ventricular tachyarrhythmia based on the morphology analysis;
• override the rejection rule for withholding a tachyarrhythmia detection by detecting ventricular tachyarrhythmia in response to the required number of tachyarrhythmia intervals being reached and the first cardiac signal segment being classified as ventricular tachyarrhythmia based on the morphology analysis;
• and
• start charging a capacitor for delivering a therapy in response to detecting the ventricular tachyarrhythmia.