Beat-morphology matching scheme for cardiac sensing and event detection

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;
• determine a template alignment point and an unknown cardiac signal alignment point in response to the fourth order difference signal;
• determine an R-wave onset and an R-wave offset in response to the fourth order difference signal of the unknown cardiac cycle signal;
• determine an R-wave width as the difference between the R-wave onset and the R-wave offset;
• determine a morphology analysis window in response to the R-wave width;
• and
• determine a first morphology match metric across the morphology analysis window.