Heart Rate Variability Behavior Research Articles

Hypertension and 1/f behavior of heart rate variability

Hypertension and 1/f behavior of heart rate variability

704 Recurrence quantification analysis describe the complex and deterministic behavior of heart rate variability in healthy subjects: Link with susceptibility to hypnosis

704 Recurrence quantification analysis describe the complex and deterministic behavior of heart rate variability in healthy subjects: Link with susceptibility to hypnosis

Nonlinear analysis of heart rate and respiratory dynamics.

The authors' findings show that quantitative measures of complexity (correlation dimension, CD) and predictability (Lyapunov exponent, LE) provide significant information about autonomic nervous system (ANS) processes. There is well-organized nonlinear behavior of heart rate variability (HRV) and respiratory movements (RESP), which can be interpreted with regard to terms such as nonlinear stochastic, regular deterministic, and chaotic. The clear identification of a physiological process only on the basis of a measured time series is difficult. Distinguishing between chaotic and nonlinear correlated stochastic processes, in particular, needs more information than that of a positive LE, noninteger CD, and nonlinearity. The additional considerations of model investigation and phase locking make chaotic underlying processes of HRV and RESP in S1 probable. The hypothesis that deviations from the normal function lead to a decreased complexity and increased predictability could be confirmed quantitatively by the estimation of CD and LE during S2 and S3. This information, which can not be found by a linear approach to time series analysis, is important for the understanding of normal and pathologically disturbed functions. The authors do not claim that their analysis replaces linear methods, but rather that a consideration of both linear and nonlinear properties may improve diagnostic classifications. The potential usefulness of dynamic nonlinear analysis presented herein is in the improved understanding of the complex processes of the ANS, and in the resulting medical concepts with regard to pathophysiological disturbances and their treatment.

Heart rate variability and functional severity of congestive heart failure secondary to coronary artery disease.

To investigate the behaviour of heart rate variability (HRV) with the advancing severity of heart failure (CHF) we studied 20 normal subjects and 80 coronary artery disease (CAD) patients in sinus rhythm. CAD patients were selected consecutively in order to form four equal groups of 20 subjects with different degrees of CHF according to the New York Heart Association (NYHA) functional classification. In each subject a 24 h ECG Holter tape was recorded and subsequently analysed to obtain measures of heart rate and HRV. We used several measures of HR and both spectral and non-spectral measures of HRV. Among these we employed the width of the R-R interval distribution over 24 h at three different heights (TV, 10%Var, 50%Var). The CAD group showed significantly lower HRV counts and smaller spectral components than controls. However, these differences were due to the presence of CHF rather than to CAD. Indeed, a progressive and significant increase in heart rate and a contemporary decrease in HRV was observed with the advancing severity of CHF. Class IV patients had the smallest HR variation; the spectral composition in this group was barely detectable. The decrease in time domain measures of HRV followed the increase in NYHA Class in a progressive and regular pattern, while the low frequency and high frequency spectral power showed the largest reduction from NYHA Class I to NYHA Class II patients. No significant change was demonstrated in NYHA Class I patients as compared to Controls.(ABSTRACT TRUNCATED AT 250 WORDS)