Patent ID: 8175708

Claim:
A method for use by an implantable medical device capable of automatically adjusting a sensitivity with which electrical cardiac signals are sensed within a patient, the method comprising: sensing electrical cardiac signals within the patient using the device while adjusting the sensitivity during individual cardiac cycles in accordance with a sensitivity adjustment procedure specified by a plurality of sensitivity adjustment parameters; determining a profile using the device that is representative of the shape of the cardiac signals, the profile including an envelope representative at least of widths of repolarization events within the individual cardiac cycles; and resetting the sensitivity adjustment parameters of the device based on the profile representative of the shape of the cardiac signals so as to reset the procedure by which the sensitivity is automatically adjusted by the device during individual cardiac cycles; and controlling at least one device function based on the cardiac signals sensed by the device; wherein the sensitivity adjustment parameters include a Decay Delay parameter specifying a duration of time following the sensed event before sensitivity is automatically decreased and a Decay Rate specifying a rate by which the sensitivity is changed following completion of the Decay Delay, wherein the rate is based on the widths of the repolarization events.