Detection of Nonlinearity in the Healthy Heart Rhythm

Abstract:

Sequences of interbeat intervals from two groups of subjects, 24 in relaxed and 10 in sleeping condition were analyzed by the nonlinear predictor method as well as by a method, proposed recently, able to directly estimate the time series nonlinearity. The nonlinear predictability of the R-R intervals is tested by using surrogate data. The results obtained with both methods show that nearly all the sequences exhibit a statistically meaningful degree of nonlinearity. This raises the question whether such nonlinearity encodes information about the physiological condition of the examined subjects.

Keywords:

Heartbeat Time Series - Nonlinear Predictors - Nonlinear Dynamics - Deterministic Chaos

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