Avaliação da função ventricular pela técnica do strain bidimensional, em indivíduos chagásicos sem cardiopatia aparente

• Ano de defesa: 2011
• Autor(a) principal: Daniel Furtado Vidigal
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Strain bidimensional T Cruzi; Indivíduo chagásico sem cardiopatia aparente; Doença de Chagas; Contração miocárdica; Disfunção ventricular direita; Doença de chagas/ultrassonografia; Chagas, Doença de; Ecocardiografia Doppler/métodos; Disfunção ventricular esquerda; Estudos transversais; Estudo observacional
• Link de acesso: http://hdl.handle.net/1843/BUBD-A32JJ5

Chagas disease is a major cause of heart failure in Brazil, with an important socioeconomic impact. Despite the current control of its transmission, it still represents a serious public health problem due to the potential of infected individuals to develop severe forms. Early detection of changes in contractility can identify subgroups of patients at risk for progression of heart disease. Recently, the development of new echocardiographic techniques, including two-dimensional strain, has allowed to quantify ventricular contractility in a more accurate and reproducible way. The aim of this study was to assess ventricular function in Chagas disease patients without overt heart disease, using two-dimensional strain. It is an observational, cross-sectional study, conducted between August 2009 and December 2010, when 78 individuals with positive serology for T. cruzi, asymptomatic without detectable heart disease, and 38 healthy subjects of similar age and sex, were enrolled. All patients underwent 12-lead electrocardiogram, analyzed according to standardized criteria for Chagas disease. Conventional echocardiography was performed for determination and assessment of ventricular function. Subsequently, images were stored in the software Echopac to obtain measures of tissue Doppler and radial, longitudinal and circumferential two-dimensional strain. Exams were performed by an examiner who was blinded of the seropositivity for T. cruzi. Intra- and interobserver variabilities of Doppler myocardial imaging parameters were tested on 10 randomly selected cases. Patients were 45 ± 9 years old, and 36 were males (46%), similar to controls. Systolic blood pressure was higher in controls, although levels were within the normal range. Mild changes in ventricular repolarization on the electrocardiogram were observed in 16 individuals (14%), with no difference between cases and controls. All conventional echocardiographic parameters of systolic and diastolic left ventricular function were similar between cases and controls. Seven individuals (9%) with Chagas disease presented with a segmental abnormality of contractility by two-dimensional echocardiogram. The right ventricular diameter and time of systolic activation were higher in cases, but the right ventricle had normal contractility. Measurements of strain were lower in several segments of the left ventricle in Chagas patients than controls. The radial strain of the basal segments of the anterior, inferior, posterior and septal walls was different between groups. The longitudinal strain of the basal segment of the inferior and septal walls and the apical segment of the posterior wall were lower in cases. In relation to the circumferential strain, only the basal segment of the anterior wall was found to be reduced in patients with Chagas disease when compared with controls. In patients with abnormal segmental contractility, the overall longitudinal strain was lower than in subjects with normal contractility (p = 0.018). The indices of systolic function correlated with the global strain. There was no difference in the two-dimensional right ventricular strain between the groups. Intra- and interobserver variability for the circumferential strain was large. This study showed for the first time that the technique of two-dimensional strain, using its three modalities (radial, longitudinal and circumferential), was able to detect changes in segmental contractility in patients with Chagas disease without overt heart disease.