Mechanisms of Periodic Heart Rate Oscillations: A Study Using Controlled Breathing Tests

Abstract

Periodic oscillations of the heart rate (HR) are determined by a complex regulatory system. Like other biorhythms, the rhythmic oscillations of the HR result from stochastic nonlinear biological mechanisms responding to changing external factors. However, most physiological oscillations are not strictly periodic; changing external factors and random disturbances ("noise") usually make the rhythms vary irregularly with time [1]. The cardiac rhythm is no exception. The mechanism of HR control mediated by the autonomic nervous system is modulated by numerous external factors (respiration, exercise, posture changes, emotional factors, etc.) [1]. This multifactorial interaction determines the complexity of studying the effects of various factors on HR variability (HRV), as well as the characteristics of the physiological oscillations in HR themselves.To simplify the understanding of the complex interand intrasystemic interactions forming the HRV, we may present this set of mechanisms as an integrated system of the autonomic nervous control of the heart (SANCH), in which respiration rate, changes in blood pressure (BP), emotions, etc., are input parameters and HRV is the output signal ( Fig. 1). Probably, various biological oscillatory mechanisms exist within this system; however, they differ in their relative contributions to the formation of the output signal. The question arises of how the roles of different internal oscillatory mechanisms in the formation of the HRV can be studied.Interactions between the cardiovascular and respiratory systems are very strong; one of their results is respiratory sinus arrhythmia [2,3]. Although the intensity of this intersystemic interaction has not been determined conclusively, the use of the functional parameters of the respiratory system for studying the characteristics of the SANCH seems promising, the more so as these parameters are easy to measure. The monitoring of the function of the respiratory system makes it possible to record most information at the input of the SANCH. Analysis of the input signals and the output signal (in the form of HRV) under different conditions of SANCH functioning allows the characteristics of the interaction between the respiratory and the cardiovascular systems and their changes with time to be described and studied in detail.Abstract -An orthostatic test with frequency-controlled breathing (with periods of 4, 6, 8, 10, and 12 s) was used to analyze frequency estimates of the heart rate variability (HRV) spectrum in the low frequency (LF) and high frequency (HF) ranges in 36 volunteers (26 men and 10 women) aged 19-21 years without signs of heart or respiratory pathology. The subjects took a breath at the moment of an auditory signal. There were no other requirements for the respiration rhythm. Variables were compared using Wilcoxon's test for pairwise comparisons; correlations were estimated by Spearman's rank correlation R test. The sensitivities of the LF and HF ranges of the HRV spectrum to periodic respiratory perturbations at different fr...

The possibility of using spectral indices of heart rate variability to improve the diagnostic value of cardiovascular autonomic function tests in rheumatoid arthritis patients

“…The response of heart autonomic control, which is studied by HRV, to external periodic disturbances (such as controlled breathing, controlled eye opening, etc.) is determined by a frequency-dependent phenomenon ( 3 , 4 ). The external 0.1-Hz disturbance at a rate of six actions per minute is a powerful factor for baroreflex control that shows itself in healthy subjects as a resonance response in the low-frequency heart rate variations ( 3 , 4 ).…”

“…is determined by a frequency-dependent phenomenon ( 3 , 4 ). The external 0.1-Hz disturbance at a rate of six actions per minute is a powerful factor for baroreflex control that shows itself in healthy subjects as a resonance response in the low-frequency heart rate variations ( 3 , 4 ). Moreover, a 0.1-Hz controlled breathing is potentially the main external factor for the study of barore-flex gain and its dysfunction.…”

“…Thus, spectral analysis of HRV can supplement the results of the study conducted by Javady Nejad et al ( 1 ). The controlled breathing can also be combined with a tilt test ( 3 ) to obtain useful additional information in the further study of cardiovascular autonomic control in RA patients.…”