[Nocturnal cardiac arrhythmias in the sleep apnea syndrome]

A day vs. night comparison of type and frequency of cardiac arrhythmias documented by long-term ECG was done in 30 patients with nocturnal respiratory disorders in the form of the sleep apnoea syndrome. The commonest nocturnal arrhythmia was pronounced sinus arrhythmia during the apnoeic phases with variations of cardiac frequency between 40 and 120/min. Supraventricular and ventricular extrasystoles occurred significantly more frequently during the night than during the day. In three patients bradycardiac arrhythmias presenting as sinoauricular and atrioventricular blockades of the 3rd degree with node or ventricular substitute rhythm were seen during the sleep apnoea which could not be demonstrated during the day. Predominantly nightly occurrence of cardiac arrhythmias should lead to differential diagnostic consideration of the sleep apnoea syndrome.