Human ECG: nonlinear deterministic versusstochastic aspects

The authors discuss aspects of randomness and determinism in electrocardiographic signals. In particular, they take a critical look at attempts to apply methods of nonlinear time series analysis derived from the theory of deterministic dynamical systems. It is argued that deterministic chaos is not a likely explanation for the short-time variablity of the inter-beat interval times, except for certain pathologies. Conversely, densely sampled full ECG recordings possess properties typical of deterministic signals. In the last-mentioned case, methods of deterministic nonlinear time-series analysis can yield new insights.