Clinical and hemodynamic correlates of sympathetic nerve activity in normal humans and patients with heart failure: Evidence from direct micronenrographic recordings

Abstract To characterize the neural excitatory state of heart failure, simultaneous measurements of efferent sympathetic nerve activity to muscle (by microneurography) and rest hemodynamics were obtained in 10 normal subjects (age 25 ± 2 years, mean ± SEM) and 29 patients with heart failure (age 49 ± 2 years; New York Heart Association functional class II to IV; left ventricular ejection fraction 21 ± 1%; cardiac index = 2.16 ± 0.13 liters/min per m 2 ; pulmonary capillary wedge pressure 23 ± 2 mm Hg). Sympathetic nerve activity was significantly higher in the patients with heart failure (54.7 ± 4.5 bursts/min) than in normal subjects (16.7 ± 2.2 bursts/min, p Multiple linear regression analyses indicated that sympathetic activity in these human subjects was most strongly and inversely correlated with left ventricular stroke work index (r = −0.86, p Direct measurements of sympathetic nerve activity correlated closely with plasma norepinephrine (r = 0.72, p