Congestive heart failure and sleep apnoea-possible mechanisms and effect of CPAP therapy.

Sleep-disordered breathing has been associated with increased cardiovascular morbidity and mortality. However, despite several plausible mechanisms whereby obstructive sleep apnoea might be associated with left ventricular dysfunction and congestive heart failure, only limited data exist linking those disorders. These studies are reviewed along with possible mechanisms leading to left ventricular dysfunction in obstructive sleep apnoea. Recent investigations demonstrating improvement in left ventricular function after CPAP therapy in patients with congestive heart failure are reviewed as well. Finally, new data are presented from an animal model of congestive heart failure demonstrating a beneficial effect of CPAP on cardiac index in association with a decline in systematic vascular resistance. Remarkably, these effects persisted even after CPAP was removed. Possible mechanisms whereby CPAP may lead to improvement in cardiac output are discussed.