Sleep-induced apnea syndrome. Prevalence of cardiac arrhythmias and their reversal after tracheostomy.

Cardiac arrhythmias during wakefulness and sleep in 15 patients with sleep-induced obstructive apnea, and the effect of atropine and tracheostomy on these arrhythmias were studied by continuous overnight Holter electrocardiographic, respiratory and electroencephalographic recordings. Sleep was characterized by marked sinus arrhythmia in 14, extreme sinus bradycardia ( less than 30 beats/minute) in six, asystole of 2.5 to 6.3 seconds in five, second degree atrioventricular (A-V) block in two, and ventricular arrhythmias--complex premature ventricular beats in 10 and ventricular tachycardia in two. Arrhythmias during wakefulness were limited to premature ventricular beats in six. Atropine administration was partially and tracheostomy highly effective in preventing the majority of these arrhythmias during sleep. Marked sinus arrhythmia during sleep is characteristic of the syndrome of obstructive sleep apnea and is frequently accompanied by potentially life-threatening tachy- and bradyarrhythmias. Possible mechanism of production of these arrhythmias, the mode of action of tracheostomy and atropine, and the probable role of similar arrhythmias in the sudden infant death syndrome are discussed.