Human EGG: nonlinear deterministic versus stochastic aspects

The authors discuss aspects of randomness and determinism in electrocardiog raphic signals. In particular, they take a critical look at attempts to app ly methods of nonlinear time series analysis derived from the theory of det erministic dynamical systems. It is argued that deterministic chaos is not a likely explanation for the short-time variablity of the inter-beat interv al 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 analysi s can yield new insights.