Patent ID: 8086304

Claim:
A method of determining a cardiac condition, the method comprising: receiving a sensed physiologic signal for a period of time including multiple cardiac cycles; determining, by a processing module using the received physiologic data, a heart beat frequency to be used as a reference frequency; extracting, by the processing module, a plurality of harmonics of the received physiologic signal based on the reference frequency, wherein the harmonics correspond to a plurality of alternans frequencies and include integer harmonics and fractional harmonics, and wherein the harmonics are extracted using one or more band pass filters, and further comprising assembling a blended signal comprising a sum of corresponding integer and fractional harmonics; and determining, by the processing module, amplitudes of at least some of the extracted harmonics and using the amplitudes to determine an alternans indicator value indicative of a patient's susceptibility to a cardiac condition or to a cardiac event, and storing the alternans indicator value in an electronic storage location.