Linear and/or Nonlinear Behavior of Heart Rate? A Comparative Study Using Lyapunov Exponents, Fractal Dimension, Conditional Entropy and Spectral Analysis
نویسندگان
چکیده
To investigate linear and nonlinear components of heart rate variability over the 24-hour period in healthy subjects, we analyzed RR interval series, derived from 70 recordings in free-living conditions (37 ± 4 years, 34 males) by different nonlinear approaches (Largest Lyapunov Exponent -LLEcomputation, quantifying exponential divergence of trajectories in the phase space; corrected conditional entropy -CCEestimating the amount of information in the signal, and pattern fractal analysis -PFD-, able to quantify the complexity of the time series), and by autoregressive spectral analysis, too. The LLE, PFD, and CCE showed a strong correlation, whereas nonlinear parameters were significantly related even with total power, VLF, LF, and HF power of the spectra. Thus, common physiological phenomena seem to modulate both linear and nonlinear behavior of heart rate in healthy human beings.
منابع مشابه
Gender-related Differences in Nonlinear Indices of Heart Rate Variability
The effect of day-night variations was evaluated in both a female and a male population of healthy subjects. A total of 239 subjects were included in this study, of which 119 male and 120 female. 24 hour Holter recordings were used to analyze heart rate variability. Power spectral indices (total power, low and high frequency power) were calculated together with the nonlinear indices fractal dim...
متن کاملEstimating Lyapunov Exponents in Chaotic Time Series with Locally Weighted Regression
Nonlinear dynamical systems often exhibit chaos, which is characterized by sensitive dependence on initial values or more precisely by a positive Lyapunov exponent. Recognizing and quantifying chaos in time series represents an important step toward understanding the nature of random behavior and revealing the extent to which short-term forecasts may be improved. We will focus on the statistica...
متن کاملAnalysis and Characterization of Complex Spatio-temporal Patterns in Nonlinear Reaction-diffusion Systems
Two important classes of spatio-temporal patterns, namely, spatiotemporal chaos and self-replicating patterns, for a representative three variable autocatalytic reaction mechanism coupled with diffusion has been studied. The characterization of these patterns has been carried out in terms of Lyapunov exponents and dimension density. The results show a linear scaling as a function of sub-system ...
متن کاملThe nonlinear Gain and the Onset of Chaos in a Semiconductor Laser with Optical Feedback
The effect of the inclusion of nonlinear gain saturation in the governing equations of a semiconductor laser with optical feedback is numerically analyzed. The dependence of the route to chaos on the intensity of the nonlinear term and on the form of gain saturation, are considered. It is found that the inclusion of gain saturation causes significant changes in the behavior of the laser with re...
متن کاملEstimating Lyapunov Exponents Inchaotic Time Series with Locallyweighted
Nonlinear dynamical systems often exhibit chaos, which is characterized by sensitive dependence on initial values or more precisely by a positive Lyapunov exponent. Recognizing and quantifying chaos in time series represents an important step toward understanding the nature of random behavior and revealing the extent to which short-term forecasts may be improved. We will focus on the statistica...
متن کامل