Obstructive sleep apnea (OSA) is the most common form of sleep-disordered 
breathing, affecting 5-15% of the population. It is characterized by 
intermittent episodes of partial or complete obstruction of the upper airway 
during sleep that disrupts normal ventilation and sleep architecture, and is 
typically associated with excessive daytime sleepiness, snoring, and witnessed 
apneas. Patients with obstructive sleep apnea present risk to the general public 
safety by causing 8-fold increase in vehicle accidents, and they may themselves 
also suffer from the physiologic consequences of OSA; these include 
hypertension, coronary artery disease, stroke, congestive heart failure, 
pulmonary hypertension, and cardiac arrhythmias. Of these possible 
cardiovascular consequences, the association between OSA and hypertension has 
been found to be the most convincing. Although the exact mechanism has not been 
understood, there is some evidence that OSA is associated with frequent apneas 
causing mechanical effects on intrathoracic pressure, cardiac function, and 
intermittent hypoxemia, which may in turn cause endothelial dysfunction and 
increase in sympathetic drive. Therapy with continuous positive airway pressure 
has been demonstrated to improve cardiopulmonary hemodynamics in patients with 
OSA and may reverse the endothelial cell dysfunction. Despite the availability 
of diagnostic measures and effective treatment, many patients with 
sleep-disordered breathing remain undiagnosed. Therefore, OSA continues to be a 
significant health risk both for affected individuals and for the general 
public. Awareness and timely initiation of an effective treatment may prevent 
potential deleterious cardiovascular effects of OSA.