Multi-scale transitions of fuzzy sample entropy of RR-intervals and their phase-randomized surrogates: A possibility to diagnose congestive heart failure

The results show distinct differences in the biphasic MST transitions between controls and patients suffering from congestive heart failure. The differences of normalized fSEn of surrogates minus fSEn of the RR-signal show a clear first, fast response lasting about 3-4 s followed by a long lasting trend. The sum of these differences in the fast response trend represent a feature variable that allowed classifying patients and controls with a high sensitivity of 87% and a high specificity of 89%. The relationship to neural control of the HRV can now be investigated with variables that reflect the regularity and complexity of the HRV using the information that is encoded in the phase of the Fourier transformed RR-signal and is not resolved by the classical, power spectra based HRV analysis.