Long-range correlations in amplitude variability of HF and LF components of heart rate variability

Abstract

For the assessment of autonomic nervous system activity based on heart rate variability (HRV) analysis, characteristics of high-frequency (HF; 0.15 to 0.4 Hz) and low-frequency (LF; 0.04 to 0.15 Hz) components have been widely employed. HF and LF band powers quantified by power spectral analysis have most commonly been used in the conventional studies; the physiological significance of these measures has also been extensively studied. However, nonlinear characteristics of HF and LF components have not been well established. In this paper, we investigated nonlinear properties of HF and LF components in 122 healthy subjects and 108 patients with congestive heart failure (CHF). By analyzing bandpass-filtered time series of HRV corresponding to HF and LF components, it is shown that amplitude variability of HF and LF components displays long-range correlation, which cannot be explained by linear HRV properties. Compared with the age-matched healthy control group, the CHF patients showed significantly decreased long range correlation of HF component amplitude variability. These findings suggest that nonlinear properties of HF and LF components provides some complementary information on HRV dynamics.

Analysis of the Relationship between Amplitude Modulation of Low Frequency Heart Rate Variability and Blood Pressure Variability

“…The resampled RRI and SBP time series were bandpass ltered through a Butterworth lter with a passband 0.04-0.15 Hz to obtain LF-HRV and LF-BPV. The instantaneous amplitude time series of LF-HRV (RRIL-Famp) and that of LF-BPV (SBPLFamp) were calculated by Hilbert transform [14,20]. RRILFamp and SBPLFamp data outside the mean ± 3SD range were not used in subsequent analyses.…”

“…The LF-HRV signal is not stationary (non-Gaussian) and its amplitude varies with time [14]. There are in nite variability patterns against a single value of LF power of HRV.…”

“…However, the variability includes both amplitude modulation and phase modulation. In this study, we discriminated the amplitude modulation from the phase modulation using signal processing techniques such as Hilbert transform [14,20]. We then applied correlation analysis to the amplitude modulation of LF-HRV time series and that of LF-BPV time series to clarify the relationship between the two.…”

ECG-based Detection and Prediction Models of Sudden Cardiac Death: Current Performances and New Perspectives on Signal Processing Techniques

“…The frequency components are grouped into three parts, which are high frequency (0.15-0.4Hz), low frequency (0.04Hz-0.15Hz) and very low frequency (0-0.04Hz). The high frequency components repre-sent synchronization between respiration cycles and HRV while low frequency components represent oscillations relation of the regulation of blood pressure and vasomotor [48]. Ratio of HF and LF is also used as additional non-linear feature for the analysis.…”