Sleep-stage regulation of ventricular arrhythmias in the unanesthetized pig.

In two groups of purebred juvenile Hampshire pigs, left anterior descending coronary occluders were implanted. The pigs were then adapted to the recording chamber until they would manifest a criterion pattern of sleep while in it. In group A, permanent coronary artery occlusions were produced, and the effects of various sleep stages on the resultant cardiac arrhythmias were observed. Sleep intervals during which transitional and slow wave (SW) sleep alternated were correlated with increased arrhythmias relative to the awake state (P less than 0.04). The increase was maximum during sustained periods of SW sleep. Intervals during which rapid eye movement (REM) sleep predominated were correlated with a reduction in arrhythmias. In group B, temporary occlusions were made during both an awake condition and after criterion patterns of either SW or REM sleep. Occlusions after SW sleep reduced the ventricular fibrillation latency compared with that during the awake control state (P less than 0.05), whereas occlusions after REM sleep increased ventricular fibrillation latency (P less than 0.05). We conclude that SW SLEEP, BUT NOT REM sleep, has a deleterious effect on the ischemic myocardium. REM sleep may have a beneficial effect, since it increases ventricular fibrillation latency. Heart rate changes do not appear to be correlated with the effects of either sleep stage.