[Disorders of the regulation of cardiac rhythm in various sleep phases and cycles in organic and functional pathology of the heart].

The purpose of the study was to examine the correlation between individual stages, phases and cycles of sleep, and the heart rate (HR) in patients with organic and functional cardiac disorders. Twenty normal subjects and 103 cardiologic patients were investigated. During sleep, tonic HR increases and dynamic changes decrease in coronary patients. During stage 4 of slow-wave sleep (SWS), HR increases in postmyocardial-infarction patients. The circadian decrease of HR disappears with every sleep cycle. Anginal patients have a disturbed HR pattern in the second SWS stage, the circadian rhythm is weak. In sleeping patients with functional disorders associated with paroxysmal atrial arrhythmias, HR changes are dependent on basal rhythm regulation type. In bradycardia, a HR slow-down is observed during paradoxical sleep, while the circadian rhythm pattern is weaker. In tachycardia, there is no typical HR slow-down during the first cycles of SWS. The circadian HR changes are clearly marked.