Patent ID: 7996082

Claim:
A method of monitoring cardiac function in an implantable cardiac rhythm device (ICRD), the ICRD comprising a plurality of electrodes adapted for implantation in a patient and operational circuitry electrically coupled to the electrodes and configured to perform analysis of cardiac signals, the method comprising: monitoring a signal produced between the electrodes; observing an event in the monitored signal; gathering a signal corresponding to and including the event in an analysis window; observing characteristic features of the slope of the signal in the analysis window; counting the characteristic features to determine the quantity of characteristic features that occur during the analysis window; comparing the quantity of characteristic features that occur in the signal during the analysis window to a threshold to: certify the event for use in characterizing a cardiac complex; or determine the event is unsuitable for use in characterizing a cardiac complex; and if the event is certified, using the event to determine whether a malignant cardiac arrhythmia is likely occurring; or if the event is not certified, excluding the event from analysis of whether a malignant cardiac arrhythmia is likely occurring.