Frequency Analysis of Ventricular Fibrillation and Resuscitation Success

SUMMARY In 56 patients, frequency analysis of the electrocardiogramof ventricular fibrillation exhibited power spectra with a distinctdominant frequency. The greatest success for resuscitation fromventricular fibrillation is recorded when ventricular fibrillationdevelops after the patient comes under coronary care. Of the41 patients in whom the onset and first 8 s of ventricular fibrillationwere artefact-free the mean dominant frequency of primary ventricularfibrillation (no cardiogenic shock or cardiac failure) in 21patients was 6.2±0.2 Hz, significantly higher than themean dominant frequency of the first 8 s of secondary ventricularfibrillation (cardiogenic shock or heart failure) (4.0±0.2Hz, 20 patients, p =0.0001). In these patients the peak-to-troughamplitude (ECG) of the first 8 s of ventricular fibrillationwas similar in both primary and secondary ventricular fibrillationas was the mean duration of ventricular fibrillation prior tothe first DC shock. There was a significantly lower successrate for resuscitation from secondary ventricular fibrillation(6 of 20 patients) compared with resuscitation from primaryventricular fibrillation (18 of 21 patients, x² 17.8, p=0.001).Of the remaining 15 patients who were collapsed between 3 and20 min before the arrival of the mobile coronary care unit,the dominant frequency of the first 8 s of ventricular fibrillationfell with increased duration of collapse (from 5.5 Hz at 3 minto a mean of 2.1 Hz at 20 min). Four of these 15 patients whosurvived the initial arrest had a mean dominant frequency of5.2±0.3 Hz, which was significantly higher than the meandominant frequency (3.1±0.3 Hz, p<0.01) of the 11patients who were not resuscitated. This study shows that low frequency ventricular fibrillationis indicative of a poor chance of successful resuscitation.Alteration of the frequency may increase resuscitation success.