Power spectral scaling and correlation properties of physical and biological dynamical systems are useful in system characterization and in giving insight into their mechanisms. Since, heart rate has been found to vary with respect to time in a very complicated manner, analysis of this variation using power spectral scaling and correlation techniques can give insight into the various physiologic systems which are involved in heart rate control. 1/f power spectrum, one of the most ubiquitous types of power spectra found in nature, has previously been found to be characteristic of normal cardiac interbeat interval time series for frequencies less than 2 X 10-2 Hz. This frequency domain corresponds to relatively long-term interbeat interval variation. The scaling properties of short-term heart rate variability (related to short-term heart rate control by the baroreceptor reflex), on the other hand, have not as yet been examined analytically. To accomplish this now, we analyzed the scaling properties of the power spectra of cardiac interbeat interval time series of five minute durations in 10 normal individuals and in 10 patients with heart failure. By studying the scaling and correlation properties of the power spectra of short-term interbeat interval time series we may gain more insight into the non-linear characteristics of baroreceptor reflex heart rate regulation.
"1/f2 and 1/f power spectra of short-term interbeat interval time series", Proc. SPIE 2036, Chaos in Biology and Medicine, (5 November 1993); doi: 10.1117/12.162705; https://doi.org/10.1117/12.162705