Effect of parasympathetic impairment on the haemodynamic response to handgrip in Chagas's heart disease

• Published in: British Heart Journal Vol. 55; no. 2; pp. 204 - 210
• Main Authors: Marin-Neto, J A, Maciel, B C, Gallo Júnior, L, Junqueira Júnior, L F, Amorim, D S
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Cardiovascular Society 01.02.1986; BMJ; BMJ Publishing Group LTD
• Subjects: Adult; Atropine - administration & dosage; Biological and medical sciences; Blood Pressure; Cardiac Output; Chagas Cardiomyopathy - physiopathology; Heart Rate - drug effects; Human protozoal diseases; Humans; Infectious diseases; Isometric Contraction; Male; Medical sciences; Middle Aged; Muscle Contraction; Parasitic diseases; Parasympathetic Nervous System - physiopathology; Protozoal diseases; Rest; Space life sciences; Trypanosomiasis; Vascular Resistance; Physical exercise; Human; Protozoal disease; Chagas disease; Cardiovascular disease; Isometric muscular contraction; Hand; Parasympathic nervous system; Infection; Myocarditis; Resistance; Blood vessel; Exercise tolerance test; Hemodynamics; Trypanosomiasis
• ISSN: 0007-0769; 1468-201X; 2053-5864
• DOI: 10.1136/hrt.55.2.204

Haemodynamic responses to sustained isometric exercise (handgrip at 30% of maximum voluntary capacity) were studied in 10 patients with Chagas's cardiopathy without previous or current heart failure. Five of the patients (group 1) had profound impairment of parasympathetic control of heart rate. They had no tachycardia in response to intravenous administration of atropine and no bradycardia during phase IV of the Valsalva manoeuvre. The other five (group 2) showed normal vagal regulation of heart rate, as judged by chronotropic responses to these tests. The heart rate change (mean (SD] elicited by the handgrip test was significantly lower in group 1 (from 93.0 (14.1) to 95.0 (16.7) beats/min) than in group 2 (from 78.2 (15.8) to 92.8 (18.1) beats/min). Pressor responses to handgrip were of similar magnitude (from 91.6 (7.8) to 109.0 (8.0) mm Hg in group 1 and from 88.6 (11.9) to 106.8 (20.9) mm Hg in group 2). In both groups no significant change in stroke index was detected during handgrip. Cardiac index increased during handgrip from 4.0 (1.2) to 4.8 (1.3) 1/min/m2 in group 2, but there was no significant change in group 1 (from 4.9 (0.7) to 4.8 (1.1) 1/min/m2). Changes in calculated systemic vascular resistance were significantly higher in group 1 (from 934 (175) to 1176 (383) dyn s cm-5) than in group 2 (from 1109 (404) to 1112 (424). This study shows that parasympathetic impairment adversely influences the haemodynamic pattern of response to isometric exercise in patients with Chagas's heart disease. In such conditions, the pressor response to handgrip is predominantly mediated by an increase in systemic vascular resistance rather than an increase in cardiac output.