Frequency analysis: a potential method to differentiate ventricular fibrillation of various etiologies

As ventricular fibrillation (VF) induced by alternating current (AC) is commonly used to replace a spontaneous VF during fibrillator implant, it is desirable to determine if loss of signal power could differentiate between VF induced by different methods. Using fast frequency transform analysis and a power spectral estimation method, the power loss in each frequency band (25 Hz per band) was examined over time during prolonged uninterrupted VF waveform in a canine model. A total of 15 VFs induced by fixed AC current (AC-VF) n=6, spontaneous post-ischemia (S-VF) n=6 and potassium chloride induced (KCL-VF) n=3 were tested in a canine model. In the AC-VF and S-VF, the power of the lower band (1-25 Hz) remained constant, whereas there was significant power loss (3.12±0.48, mean standard deviation) in 26-125-Hz bands during the initial 135±12 sec (p<0.01) and a plateau thereafter. However, in S-VF as compared to AC-VF, a greater (3.56±0.55 vs 2.68±0.42) and faster (126±13.27 sec vs 146±11.22 sec, p<0.01) loss of signal power was observed in the frequency bands 51-125 Hz