Analysis of the ventricular fibrillation ECG with methods from nonlinear dynamics

Abstract

Ventricular fibrillation (VF) ECGs (electrocardiograms) show rapid and irregular oscillations described by cardiologists as 'chaotic'. To investigate whether the observed chaotic rhythm reflects a model of deterministic chaos, a dimensional analysis of four VF ECGs obtained from the American Heart Association Database has been carried out. The correlation dimension D calculated at embedding dimension equal to 20 gives values ranging from 7.7 to 9.5. Since D, as a function of the embedding dimension does not show a complete saturation, it turns out that low-dimensional models cannot account for the dynamics of the fibrillation ECG. A comparison between correlation dimensions obtained during VF and sinus rhythm (literature data range from 3.6 to 5.2) suggests a potential relevance of this new parameter in a comparative sense.<>