During orthostatic and mental challenges, the baroreflex-based peripheral mechanism becomes significantly more important in generating respiratory sinus arrhythmia compared to supine rest.
Cross-Sectional (n=78)
No
Does orthostatic or cognitive challenge alter the mechanisms of respiratory sinus arrhythmia generation in healthy volunteers?
This study demonstrates that while both central and peripheral mechanisms generate respiratory sinus arrhythmia, the baroreflex-mediated peripheral mechanism dominates during orthostatic and cognitive stress.
p-value: p=<0.0001
Ventilation related heart rate oscillations - respiratory sinus arrhythmia (RSA) - originate in human from several mechanisms. Two most important of them - the central mechanism (direct communication between respiratory and cardiomotor centers), and the peripheral mechanism (ventilation-associated blood pressure changes transferred to heart rate via baroreflex) have been described in previous studies. The major aim of this study was to compare the importance of these mechanisms in the generation of RSA non-invasively during various states by quantifying the strength of the directed interactions between heart rate, systolic blood pressure and respiratory volume signals. Seventy-eight healthy volunteers (32 male, age range: 16.02-25.77 years, median age: 18.57 years) participated in this study. The strength of mutual interconnections among the spontaneous beat-to-beat oscillations of systolic blood pressure (SBP), R-R interval (RR signal) and respiration (volume changes - RESP signal) was quantified during supine rest, orthostatic challenge (head-up tilt, HUT) and cognitive load (mental arithmetics, MA) using bivariate and trivariate measures of cardio-respiratory information transfer to separate baroreflex and nonbaroreflex (central) mechanisms. Our results indicate that both basic mechanisms take part in RSA generation in the intact cardiorespiratory control of human subjects. During orthostatic and mental challenges baroreflex based peripheral mechanism becomes more important.
Krohová et al. (Wed,) conducted a cross-sectional in Healthy volunteers (n=78). Orthostatic challenge (head-up tilt) and cognitive load (mental arithmetics) vs. Supine rest was evaluated on Difference between bivariate and trivariate causal coupling indexes (degree of indirectionality) from respiration to RR interval (p=<0.0001). During orthostatic and mental challenges, the baroreflex-based peripheral mechanism becomes significantly more important in generating respiratory sinus arrhythmia compared to supine rest.