In recent years, new dynamic methods of HRV quantification have been used to uncover nonlinear fluctuations in heart rate that are otherwise not apparent. These nonlinear variations would enable the cardiovascular system to respond more quickly to changing conditions. Several methods have been proposed to quantify these fluctuations on the basis of the scaling properties of the heart rate variations Detrended Fluctuation Analysis, Correlation Dimension (CD), Entropy (ApEn and SampEn) or other nonlinear properties (Poincaré plots). Moreover, fractal analysis of HRV was more sensitive to the classical spectral and time-domain analysis of HRV.
The investigation of new parameters, descriptive of the complex regulation mechanisms of heart rate, has to be encouraged because not all information in the HRV signal is captured by traditional methods. The new technologies thus could provide additional physiological, and clinical meaning
