Patent ID: 7734336

Claim:
A method of detecting a cardiac event with a medical device comprising a plurality of electrodes forming a first sensing vector and a second sensing vector, comprising: sensing cardiac signals from the plurality of electrodes; determining a first number of inflections of the sensed cardiac signals sensed along the first sensing vector during a predetermined window; determining a second number of inflections of the sensed cardiac signals sensed along the second sensing vector during the predetermined window; generating a first pulse amplitude threshold in response to the first number of inflections and a second pulse amplitude threshold in response to the second number of inflections; identifying the first sensing vector as one of noisy and not noisy based, at least in part, on the first number of inflections and the first pulse amplitude threshold; identifying the second sensing vector as one of noisy and not noisy based, at least in part, on the second number of inflections and the second pulse amplitude threshold; identifying the first sensing vector as being available for therapy delivery based, at least in part, on the first sensing vector being at least one of not noisy, and both noisy and shockable; identifying the second sensing vector as being available for therapy delivery based, at least in part, on the second sensing vector being at least one of not noisy, and both noisy and shockable; and delivering therapy based, at least in part, on at least one of the first sensing vector and the second sensing vector being identified as available for therapy delivery.