The incidence of premature contractions in coronary patients during the sleep-awake cycle.
Mean heart rates and their variability indices during REM sleep and the frequency of cardiac arrhythmias during the sleep-awake cycle were determined in a group of coronary patients with disturbances of cardiac rhythm. In some patients there was a temporal relationship of atrial and ventricular premature contractions with slow-wave sleep, REM sleep or wakefulness. However, when they were considered as a group, no significant correlation could be observed. Furthermore, the sinus arrhythmia characteristic of REM sleep was not found to be exaggerated in those patients.