Periodic breathing in heart failure: bridging the gap between the sleep laboratory and the exercise laboratory.

In the 19th century, Cheyne 1 and Stokes2 described a pattern of periodic breathing in patients with heart failure, but over the past few decades, particular attention has been given to the occurrence of periodic breathing during sleep.3,4 Central sleep apnea, also referred to as CheyneStokes respiration, is an abnormal periodic breathing pattern in which central apneas and hypopneas alternate with periods of hyperventilation that have a waxing-waning pattern of tidal volume that classically has been associated with severe decompensated heart failure.4 Up to 37% of patients with heart failure may present obstructive sleep apnea,5 in which there is complete or partial collapse of a narrowed pharynx; as many as 40% of heart failure patients may present central sleep apnea,6 in which there is reduction in central inspiratory drive. Despite the fact that obstructive sleep apnea and central sleep apnea have different mechanisms, both are associated with increased sympathetic activity at night and during daytime that results in vasoconstriction, an increased peripheral vascular resistance.3,4 Moreover, small cohort studies had previously demonstrated that the presence of central sleep apnea is associated with increased mortality in heart failure.7,8