Chronotropic-metabolic index in Chagas' disease

Revista da Sociedade Brasileira de Medicina Tropical

Universidade de Minas Gerais, Belo Horizonte¹  Rocha, Ana Luiza Lunardi¹  Barros, Márcio Vinícius Lins¹  Rocha, Manoel Otávio da Costa¹  Lombardi, Federico¹  Bittencourt, Roberto José¹  Ribeiro, Antonio Luiz Pinho¹  Abreu, Cláudia Drumond Guimarães¹  Ecoar - Medicina Diagnóstica, Belo Horizonte, Brasil¹  Teixeira, Bruno Otávio Soares¹  Università di Milano, Milão, Itália¹  Universidade Federal of Minas Gerais, Belo Horizonte¹ 

关键词: Chagas' disease;    Autonomic nervous system;    Chronotropism;   

DOI  :  10.1590/S0037-86822005000500001

学科分类：农业科学（综合）

来源: Sociedade Brasileira de Medicina Tropical

【 摘 要 】

Chronotropic incompetence is a common feature in Chagas' disease patients. New methodologies are now available to evaluate the chronotropic response in different subsets. The chronotropic-metabolic index (CMI) is one of these new indexes and quantifies the relationship between the increment of heart rate and the maximal oxygen consumption (VO2 max) during exercise testing. In normal subjects there is linear response and the index is round 1.0. The aim of the study was to evaluate the chronotropic response in healthy controls and Chagas' disease patients with and without left ventricular dysfunction, using CMI. Twenty-four controls and 171 Chagas' disease patients underwent a clinical protocol and maximal exercise testing. Chagas' disease patients were divided into two groups: Ch1= patients with ejection fraction (EF) > 39% and Ch2= EF<40%. CMI was analyzed and calculated according to the Wilkoff method. Chagas' disease patients were older than controls and showed higher prevalence of right bundle branch block, as well as lower VO2 max during exercise. Both groups of Chagas' disease patients showed a less steep curve in the chronotropic-metabolic index (Ch1: 0.91±0.10, Ch2: 0.89±0.08) than controls (1.0±0.12, p< 0.001). Chagas' disease patients with and without left ventricular dysfunction chronotropic incompetence may exhibit reduced chronotropic response to exercise, expressed by a less steep chronotropic-metabolic index.

【 授权许可】

Unknown