Relation between intracardiac and surface ECG signals during the onset of human ventricular fibrillation

The mechanism of human ventricular fibrillation (VF) remains elusive. This study compared the spectra of electrograms and surface ECG signals recorded during human VF. Six episodes of VF were recorded during electrophysiology studies. ECG signals were recorded from leads I, aVF and V2, and a bipolar electrogram recorded from the right ventricular apex (RVA). The RVA signal was rectified and low pass filtered. The first 10 s of each VF was separated into ten 1 s epochs. The spectrum of each epoch was estimated with an FFT algorithm and the frequency of the dominant peak (DomF) calculated. Mean (SD) DomF increased from 4.25 (1.00) Hz at 1 s to 5.65 (0.92) Hz at 10 s in the ECG recordings and 4.72 (0.91) Hz at 1 s to 6.55 (1.53) Hz in the RVA recordings. In 40% of the epochs included in this study, a similar value of DomF was seen in all three ECG leads and the RVA lead. This study shows a degree of similarity between surface ECG and intracardiac signals during the early stages of human VF.