title: Augmentation of parasympathetic nerve function in patients with extrinsic bronchial asthma--evaluation by coefficiency of variance of R-R interval with modified long-term ECG monitoring system.
abstract: Patients with bronchial asthma (BA) have evidence of increased vagal cholinergic tone. Although the cardiovascular-respiratory tests used in the past might have been biased by concomitant chest disease, coefficiencies of variance of the R wave to R wave (RR) interval (CVR-R) on electrocardiogram (ECG) have been applied to many diseases as a method of functional evaluation of the parasympathetic nerve system. In 24 hour recordings of ECG (Holter ECG), continuous values of CVR-R have been determined for each one-minute period with a recently developed long-term ECG monitoring system. To examine functional augmentation of parasympathetic nerve in patients with BA, we applied this system in the present study to determine the alteration of parasympathetic nerve function during an inhaled methacholine provocation test in 14 patients and 7 healthy subjects. CVR-R values were calculated from the collection of a 24-hour electrocardiogram. Bronchial response, which was measured by methacholine inhalation, was evaluated with the baseline value of respiratory resistance (Rrs-cont), the cumulative dose producing a 35% decrease in respiratory conductance (PD35Grs) and the minimum cumulative dose required to start to decrease respiratory conductance from baseline (Dmin). The serum concentrations of epinephrine and norepinephrine were measured at the basal and double-increased levels of respiratory resistance during the inhalation test. The increased values of CV(R-R) in asthmatic patients were intimately associated with augmented respiratory resistance. The disparity of CV(R-R) values (delta CV) during the resistance levels from basal to double in the asthmatic group was significantly greater than that in the control group. The absolute change of CV(R-R) values in the asthmatic group was significantly larger than that in the control group. There was a significant correlation between delta CV and Dmin (r = 0.536, p < 0.05), and between delta CV and PD35Grs (r = 0.552, p < 0.05). The serum concentrations of epinephrine and norepinephrine were not significantly different during the methacholine inhalation provocation test. We conclude that alteration of the values of CV(R-R), which were calculated with a modified long-term ECG recording system, may reflect the change of parasympathetic nerve function and the severity of bronchial hyperreactivity, and this system can be a useful non-invasive method for evaluation of increased vagal tone in patients with bronchial asthma.
authors.affiliation: Department of Internal Medicine, Kobe University School of Medicine.
authors.forename: A
authors.initials: A
authors.lastname: Hashimoto
authors.forename: H
authors.initials: H
authors.lastname: Maeda
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology*
chemical_list: D016210:Methacholine Chloride