Baroreflex and central heart rate control during wakefulness and sleep

The goal of the study was an analysis of BRS and central control of HR and blood pressure (BP) during shifts of sleep stages. Methods. The contingent was 11 healthy subjects (H Ss) and 73 coronary artery disease (CAD) pts. Autonomic HR control was investigated by means of HR power spectrum analysis during individual sleep stages. Continuous recording of BP and RR intervals was done by Portapres methodology in parallel to polysomnography, used for identification of sleep stages. BRS sensitivity was assessed as the slope of regression line between spontaneous increases or decreases of systolic BP and RR intervals, while central sensitivity (CC) after distinction of episodes with opposite their changes. Results. HR frequency decreased during deep non-REM sleep and increased during REM sleep and was followed by a decrease and an increase of HR variability in H Ss and CAD pts. Systolic BP was changing mainly in opposite to baroreflex control mode. BRS at wakefulness was depressed in CAD pts as compared to H Ss (7.7 vs. 11.2 ms/mmHg) and remained at a lower level during all sleep stages. There was significant decrease of BRS in CAD pts only during REM sleep (6.2 vs. 9.8 ms/mmHg), CC was significantly lower in CAD pts as compared to H Ss in wakefulness. CC changes during shifts of sleep stages were non significant in both H Ss and CAD pts. Conclusions. Baroreflex sensitivity was depressed in CAD pts at wakefulness and sleep. CAD pts demonstrated significant decrease of BRS during REM sleep. Central control was depressed in CAD pts only at wakefulness. Keywords: baroreflex, autonomic heart rate control, sleep, coronary artery disease.