Frequency analysis of the human and swine electrocardiogram during ventricular fibrillation

Recent studies in swine have suggested that estimating the duration of ventricular fibrillation (VF) could have important implications regarding the selection of the best therapeutic intervention during cardiopulmonary resuscitation (CPR). Successful defibrillation resulting in a pulsatile rhythm is more likely with VF of short duration, whereas VF of longer duration may require interventions designed to augment myocardial blood flow prior to defibrillation. Duration of VF has been estimated in a swine model by modelling the median frequency (FM) of the VF ECG signal. The purpose of this study was to characterize the time course of the FM ECG signal in humans during VF and compare the characteristics of the human VF ECG signal to that previously described in swine. Seven two-channel human VF ECG recordings were analyzed via fast Fourier transformation. The FM was extracted from each four-second segment of the recordings and plotted versus time. The FM in humans followed a repeatable time course during VF. The human data revealed an FM which had two peaks with subsequent gradual decline. The data in swine revealed an FM during VF which decreased initially then increased to a peak followed by a gradual decline. Our preliminary results demonstrate that a characteristic median frequency exists in humans which could be used to estimate the duration of VF.