Beat-morphology matching scheme for cardiac sensing and event detection

A medical device for classifying cardiac beats for use in detecting cardiac rhythms, comprising:

• a plurality of electrodes for sensing sensing a cardiac signal over a plurality of cardiac cycles;
• and
• a processor configured to determine a template of a known cardiac signal in response to the cardiac signal sensed over the plurality of cardiac cycles;
• sense an unknown cardiac signal over an unknown cardiac cycle;
• determine a fourth order difference signal corresponding to the template and a fourth order difference signal of the unknown cardiac signal;
• determine a first morphology match metric between the template fourth order difference signal and the fourth order difference signal of the unknown cardiac signal;
• and
• classify the unknown cardiac signal in responsed to the determined first morphology match score.

A non-transitory, computer-readable medium storing a set of instructions, which when executed by a processor of a medical device causes the device to:

• sense a cardiac signal over a plurality of cardiac cycles using a plurality of electrodes coupled to a sensing module;
• determine a template of a known cardiac signal in response to the cardiac signal sensed over the plurality of cardiac cycles;
• sense an unknown cardiac signal over an unknown cardiac cycle;
• determine a fourth order difference signal corresponding to the template and a fourth order difference signal of the unknown cardiac signal;
• determine a first morphology match metric between the template fourth order difference signal and the fourth order difference signal of the unknown cardiac signal;
• and
• classify the unknown cardiac signal in responsed to the determined first morphology match score.