Obstructive and
central sleep apnea are common in patients with
congestive heart failure (CHF). These sleep-related breathing disorders are characterized by two pathophysiologic features that could have important implications for
disease progression in CHF: sympathetic nervous system activation, and adverse changes in cardiac loading conditions. In patients with
obstructive sleep apnea, blood pressure is frequently elevated as a result of excessive sympathetic nervous system activity elicited by the combination of
apnea,
hypoxia, and arousals from sleep. The generation of exaggerated negative intrathoracic pressure during obstructive
apneas further increases left ventricular afterload, reduces cardiac output, and may promote the progression of pump failure. Increased afterload and
hypoxia can also predispose such patients to
myocardial ischemia and arrhythmias. In patients with CHF, abolition of coexisting
obstructive sleep apnea by
nasal continuous positive airway pressure improves left ventricular function.
Central sleep apnea (i.e.,
Cheyne-Stokes respiration) is also characterized by
apnea,
hypoxia, and increased sympathetic nervous system activity and, when present in CHF, is associated with increased risk of death. Recent medium-term trials involving small numbers of patients have demonstrated that nocturnally applied
continuous positive airway pressure in patients with CHF and
central sleep apnea alleviates
central sleep apnea, improves left ventricular function, reduces sympathetic nervous system activity and improves symptoms of CHF. These studies emphasize the importance of considering obstructive and
central sleep apnea in the differential diagnosis of conditions that could contribute to the development or progression of CHF. They also suggest that
continuous positive airway pressure is a promising nonpharmacologic adjunctive
therapy for patients with CHF and coexisting sleep-related breathing disturbances that warrants further investigation.