Analysis of the body surface ECG measured in independent leads during ventricular fibrillation in humans.

The degree of myocardial electrical organization during ventricular fibrillation remains unknown. The aim of this study was to compare the characteristics of the surface ECG on three independent and approximately orthogonal leads. Ten recordings of ventricular fibrillation, each induced at electrophysiology study and successfully terminated by direct current shock, were analyzed. Each recording was divided into 1-second epochs for analysis. Frequency analysis using the Fast Fourier Transform showed that the frequency of the dominant spectral peak increased significantly from a mean of 4.1 +/- 0.8 Hz to 5.2 +/- 0.7 Hz during the first 5 seconds of ventricular fibrillation. In 95% of the epochs analyzed, a similar dominant frequency was observed on either two or three ECG leads. Frequency agreement tended to increase as ventricular fibrillation evolved. This study shows that the rate of ventricular fibrillation increases rapidly during the first 5 seconds but only gradually thereafter, and that similar signal characteristics are observed on independent ECG leads. These findings are not compatible with the traditional view of incoherent myocardial activity during ventricular fibrillation.