Fractality in electrocardiographic waveforms for healthy subjects and patients with ventricular fibrillation

Detrending fluctuation analysis was used to look for fractality and to quantify time correlations in long-term (about 24 h) electrocardiographic (ECG) waveforms for presumably healthy subjects and patients with ventricular fibrillation. Our results show that ECG intrabeat dynamics of healthy subject displays a type of non-correlated behavior, perhaps reflecting diverse conduction pathways or certain degree of adaptability to changing conditions. On the other hand, ECG dynamics for ventricular fibrillation condition shows behavior similar to 1/f noise, and even large peaks around Brownian motion during a ventricular fibrillation crisis. In this way, the scaling exponents estimated with DFA can be used to discriminate electrophysiological abnormalities, and to monitoring the onset of ventricular fibrillation crises.