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Exercise Training Increases Baroreflex Control of Heart Rate and Decreases Muscle Sympathetic Nerve Activity in Chronic Chagasic Cardiomyopathy Patients
Author(s) -
Sarmento Adriana Oliveira,
AntunesCorrea Ligia Moraes,
Lobo Denise Moreira Lima,
Carvalho Bruna Elisa Piovezani,
Trombetta Ivani Credidio,
Alves Maria Janieire Nazaré Nunes,
Rondon Maria Urbana Pinto Brandão,
Rondon Eduardo,
Vieira Marcelo Luiz Campos,
Mady Charles,
Negrao Carlos Eduardo,
Ianni Barbara Maria
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.995.4
Subject(s) - medicine , baroreflex , heart rate , microneurography , cardiology , ejection fraction , asymptomatic , heart failure , cardiomyopathy , heart rate variability , blood pressure , anesthesia
Asymptomatic or mild symptomatic chronic chagasic cardiomyopathy (CCC) patients even with preserved ventricular function already have autonomic dysfunction. It is well known that decreased baroreflex control of heart rate (HR) and increased muscle sympathetic nerve activity (MSNA) increases mortality of patients with ventricular dysfunction to mortality, and that exercise training (ET) improves cardiovascular autonomic function of these patients. However, the effects of ET on baroreflex control of HR and MSNA in CCC patients with preserved ventricular function are unknown. We hypothesized that ET would increase baroreflex control of HR and decrease MSNA of these patients. Twenty CCC patients with electrocardiographic alterations and ejection fraction (EF)>55% were randomly divided into 2 groups: exercise‐trained (n=8; 47.8±2.5 yrs) and untrained (n=12, 51.7±2.4 yrs). Baroreflex control of HR (ECG) was assessed by stepwise intravenous infusions of phenylephrine and sodium nitroprusside and analyzed by linear regression. MSNA was measured using microneurography. BP was monitored on a beat‐to‐beat basis. Peak VO 2 was determined by cardiopulmonary exercise test and cardiac function by echocardiography. ET consisted of three 60‐minute exercise sessions per week on a cycle ergometer for four months. There were no significant differences in gender, age and body mass index among groups. Under baseline conditions (before training), HR, BP, Peak VO 2 , MSNA and baroreflex control of HR were similar among groups. ET decreased resting HR (67.8±3.6 vs 59.7±3.7 bpm, P =0.009) and increased peak VO 2 (25.5±2.6 vs 29.6±1.5 ml/kg/min, P =0.04) whereas there was no change in BP. ET increased baroreflex control of HR in response to phenylephrine infusion (0.24±0.1 vs 0.46±0.1, P =0.01). Furthermore, ET also reduced MSNA (31.8±3.3 vs 22.4±2.8 bursts/min, P =0.04). In conclusion, ET enhanced cardiovascular autonomic function in CCC patients with electrocardiographic alterations and preserved ventricular function. These findings highlight importance of including ET in the treatment of these patients which may lead to a better prognosis of them. Support or Funding Information This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP ‐ #2011/17533‐6d) and, in part, by Fundação Zerbini. Adriana O Sarmento was supported by Conselho Nacional de Pesquisa (CNPq, #142179/2013‐2). Ligia M Antunes‐Correa was supported by FAPESP (#2013/15651‐7). Denise ML Lobo was supported by Conselho Nacional de Pesquisa (CNPq #140265/2013‐9). Carlos E Negrao and Maria UPB Rondon were supported by CNPq (#301867/2010‐0 and #308068/2011‐4, respectively).