Effect of Cheyne-Stokes Respiration on Muscle Sympathetic Nerve Activity in Severe Congestive Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

Severe congestive heart failure (CHF) is associated with Cheyne-Stokes (C-S) respiration, which may be an index of poorer prognosis. The mechanisms linking C-S respiration to poorer functional status and prognosis in patients with CHF are unknown. We tested the hypothesis that C-S respiration increases muscle sympathetic nerve activity (MSNA) in 9 patients with CHF. Oxygen saturation was 96 ± 1% during normal breathing and 91 ± 1% after the apneic episodes (p <0.05). Mean blood pressure was 79 ± 8 mm Hg during normal breathing and 85 ± 8 mm Hg during C-S respiration (p = 0.001). C-S respiration increased MSNA burst frequency (from 45 ± 5 bursts/min during normal breathing to 50 ± 5 bursts/min during C-S respiration; p <0.05) and total integrated nerve activity (to 117 ± 7%; p <0.05). We also studied an additional 5 patients in whom C-S breathing was constant, without any periods of spontaneous normal breathing. In these patients, MSNA was higher (65 ± 5 bursts/min) than MSNA in patients in whom C-S breathing was only intermittent (45 ± 5 bursts/min; p <0.05). In all 14 patients, the effects of different phases of C-S respiration were examined. MSNA was highest during the second half of each apnea (increasing to 152 ± 14%; p <0.01) and blood pressure was highest during mild hyperventilation occurring after termination of apnea (p <0.0001). We conclude that C-S respiration decreases oxygen saturation, increases MSNA, and induces transient elevations in blood pressure in patients with CHF.