System and method for accurately detecting cardiac events using multi-threshold processing

A system that detects the time of occurrence of a cardiac event of a heart, the system comprising:

• a sensing circuit that senses electrical activity of the heart to generate an electrogram of the heart;
• an event detector that acts upon the electrogram, the event detector having a plurality of thresholds, the electrogram having an amplitude for crossing a plurality of the thresholds;
• and
• a processor that stores an electrogram template and determines a characteristic identifying feature of the electrogram at each of the plurality of threshold crossings of the electrogram, compares the determined characteristic identifying features to the electrogram template, and identifies the time of occurrence of the cardiac event based upon the comparison.

In an implantable cardiac device, a system that detects the time of occurrence of a cardiac event of a heart comprising:

• a sensing circuit that senses electrical activity of the heart to generate an electrogram of the heart;
• an event detector that acts upon the electrogram, the event detector having a plurality of thresholds, the electrogram having an amplitude for crossing a plurality of the thresholds;
• and
• a processor that stores an electrogram template and determines a characteristic identifying feature of the electrogram at each of the plurality of threshold crossings of the electrogram, compares the determined characteristic identifying features to the electrogram template, and identifies the time of occurrence of the cardiac event based upon the comparison.