Cardiac autonomic responses to volume overload in normal subjects and in patients with dilated cardiomyopathy

1 Institute of Internal Medicine, Cardiology and Heart Surgery, University of Naples Federico II, 80131 Naples; 2 Institute of Cybernetics, National Research Council, 80072 Naples; and 3 Department of Experimental Medicine and Pathology, University of Rome "La Sapienza, " 00161 Rome, and Istituto di Ricovero e Cura a Carattere Scientifico, Istituto Neurologico Mediterraneo, 86077 Pozzilli, Italy This study evaluated the effects of acute isotonic volume expansion on heart rate variability (HRV) in 10 patients with dilated cardiomyopathy (DCM) and in 10 age- and sex-matched normal volunteers. Echocardiographic left ventricular volumes and HRV measurements by continuous Holter recording were assessed at baseline, at 60 and 120 min during intravenous saline load (0.9% NaCl, 0.25 ml · kg 1 · min 1 ), and 60 min after infusion was terminated. Data analysis was performed by repeated-measures ANOVA. After volume expansion, left ventricular ejection fraction increased ( F = 9.8; P