title: Cardiac autonomic responses to volume overload in normal subjects and in patients with dilated cardiomyopathy.
abstract: 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 < 0.001) in normal subjects and decreased (F = 8.7; P < 0.001) in DCM patients. During volume expansion a significant difference was also detectable between the two groups in root-mean-square successive difference (F = 25.2; P < 0.001), percentage of differences between successive normal R-R intervals >50 ms (F = 97.6; P < 0.001), high-frequency power (F = 50.1; P < 0.001), and low-frequency power (F = 41.6; P < 0.001), all of which reflect parasympathetic modulation of heart rate; in fact, these measurements increased in normal subjects and decreased in DCM patients. In normal subjects, the increase in HRV measurements during volume expansion suggests a parasympathetic activation, mediated by stimulation of cardiopulmonary and arterial mechanoreceptors. On the contrary, in DCM patients the parasympathetic withdrawal, already detectable at baseline, increases during volume expansion.
authors.affiliation: Institute of Internal Medicine, University of Naples Federico II, 80131 Naples, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Spinelli
authors.forename: M
authors.initials: M
authors.lastname: Petretta
authors.forename: F
authors.initials: F
authors.lastname: Marciano
authors.forename: G
authors.initials: G
authors.lastname: Testa
authors.forename: M A
authors.initials: MA
authors.lastname: Rao
authors.forename: M
authors.initials: M
authors.lastname: Volpe
authors.forename: D
authors.initials: D
authors.lastname: Bonaduce
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001775:Blood Circulation / Q000187:drug effects; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology*; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D006940:Hyperemia / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010952:Plasma Substitutes / Q000494:pharmacology; D012016:Reference Values
chemical_list: D010952:Plasma Substitutes