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 mec hanisms linking C-S respiration to poorer functional status and progno sis 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 breat hing and 91 +/- 1% after the apneic episodes (p <0.05). Mean blood pre ssure was 79 +/- 8 mm Hg during normal breathing and 85 +/- 8 mm Hg du ring 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 ne rve 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 s pontaneous normal breathing. In these patients, MSNA was higher (65 +/ - 5 bursts/min) than MSNA in patients in whom C-S breathing was only i ntermittent (45 +/- 5 bursts/min; p <0.05). In all 14 patients, the ef fects of different phases of C-S respiration were examined, MSNA was h ighest 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 apnea (p <0.0001). We conclude that C-S r espiration decreases oxygen saturation, increases MSNA, and induces tr ansient elevations in blood pressure in patients with CHF. (C) 1998 by Excerpta Medica, Inc.