Obstructive sleep apnea and cardiovascular disease.

Obstructive sleep apnea (OSA) is a sleep-disordered breathing condition, which is increasingly being recognized as having wide-ranging pathophysiological effects on multiple organ systems. Although multiple factors affect the incidence and severity of OSA, male sex and obesity seem to play an influential role. The apnea-ventilation cycle, characterized by abnormalities in gas exchange, exaggerated respiratory effort and frequent arousals, has been shown to have deleterious effects on circulatory hemodynamics, the autonomic milieu, hormonal balance, inflammatory and coagulation cascades, endothelial function, and the redox state, with potential cardiovascular significance. Consequently, OSA is being increasingly implicated in a multitude of cardiovascular diseases (CVD) such as hypertension, congestive heart failure, atrial fibrillation, stroke, coronary artery disease, pulmonary hypertension, and metabolic syndrome. The strength of association for individual CVD is varied, and outcomes of clinical studies are conflicting. In addition, obesity, which is closely linked to both OSA and CVD, makes it harder to ascertain the independent role of OSA on CVD. Although available evidence is inconclusive, there is an increasing recognition of the direct role for OSA in CVD. Similarly, although several studies have demonstrated the cardiovascular benefits of OSA treatment, further studies are needed to confirm this.