Obstructive sleep apnea syndrome and cardiac arrhythmias

Obstructive sleep apnea syndrome (OSAS) refers to recurring episodes of upper respiratory track obstruction and frequent decreases in arterial oxygen saturation due to repetitive occlusions of the posterior pharynx during sleep. Its prevalence in adult population is 4% in men and 2% in women. The most important causes of morbidity and mortality in affected patients are traffic accidents and cardiovascular complications including systemic arterial hypertension, coronary artery disease, congestive heart failure, and cardiac arrhythmias. The initial phases of apnea are associated with a transient increase in the parasympathetic activity resulting in bradyarrhythmias, followed by tachycardias due to increased sympathetic activity and arousal after the end of apnea episodes. The most frequent arrhythmia in OSAS is cyclic variation of heart rate. Most of the arrhythmias seen in OSAS are secondary to OSAS and disappear with OSAS treatment, without any electro-physiological conduction system abnormalities.