[Post-extrasystolic potentiation in chronic Chagas' heart disease. A radiologic contrast ventriculography study]. / Potenciação pós-extra-sistólica na cardiopatia chagásica crônica: estudo com ventriculografia de contraste radiológico.

OBJECTIVE: To determine the existence and frequency of the phenomenon of post-extrasystolic potentiation in dyssynergic myocardial areas of patients with chronic Chagas' heart disease studied by use of radiologic contrast ventriculography. METHODS: This study is a semiquantitative retrospective analysis of radiologic contrast ventriculography in patients with chronic Chagas' disease, who were consecutively studied to assess the mechanisms of ventricular tachycardia. RESULTS: Of the 72 patients initially included, in only 20 patients was possible the ventriculographic analysis for the purposes of this study. The phenomenon of post-extrasystolic potentiation was observed in 11 (55%) of these patients, and a 15.31% improvement was observed in the contractility score from the baseline to the post-extrasystole condition (P=0.0001). That phenomenon occurred even in ventricular segments with an intense deficit in contractility. CONCLUSION: The phenomenon of post-extrasystolic potentiation is observed in a significant proportion of patients with chronic Chagas' heart disease, in whom the phenomenon could be angiographically analyzed, indicating the existence of potentially recruitable contractile reserve in ventricular regions, showing marked dyssynergy. Additional studies for clarifying the underlying mechanisms are required.

Potenciação pós-extra-sistólica na cardiopatia chagásica crônica: estudo com ventriculografia de contraste radiológico / Post-extrasystolic potentiation in chronic Chagas' heart disease: a radiologic contrast ventriculography study

OBJETIVO: Determinar a existência e freqüência do fenômeno da potenciação pós-extra-sistólica em áreas miocárdicas discinérgicas de pacientes com cardiopatia chagásica crônica estudados por ventriculografia de contraste radiológico. MÉTODOS: Análise retrospectiva semiquantitativa da ventriculografia de contraste radiológico em pacientes com cardiopatia chagásica crônica, consecutivamente estudados para avaliação de mecanismos de taquicardia ventricular. RESULTADOS: De 72 pacientes inicialmente incluídos, apenas em 20 o ventriculograma foi analisável para os propósitos do estudo. O fenômeno da potenciação pós-extra-sistólica foi verificado em 11 (55 por cento) desses pacientes, obtendo-se melhora de 15,31 por cento no escore de contração, da situação basal para a de pós-extra-sístole (p= 0,0001). Sua ocorrência verificou-se mesmo em segmentos ventriculares com déficit intenso de contratilidade. CONCLUSAO: O fenômeno da potenciação pós-extra-sistólica é verificável em proporção significante de pacientes com cardiopatia chagásica crônica em que, angiograficamente, foi possível analisar o fenômeno, indicando a existência de reserva contrátil, potencialmente recrutável, em regiões ventriculares, exibindo discinergia acentuada. Estudos adicionais para se entender os mecanismos subjacentes são requeridos.

Studies of the coronary circulation in Chagas' heart disease

Pathogenesis of chronic Chagas' heart disease may include various disturbances in the coronary circulation, that could be responsible for the myocardial lesions seen in human hearts and in experimental models of the disease. In this paper we critically reviewed the anatomical and functional abnormalities described in chronic chagasic patients, pertaining to the so-called vascular pathogenetic theory of Chagas' disease. The epicardial coronary arteries are usually tree of significant obstructive disease in nonselected groups of chagasic patients examined at autopsy or by coronary angiography. However, chagasic patients who were studied after an episode of acute myocardial infarction, show the same patterns of atherosclerotic coronary artery disease seen in the general nonchagasic population. Studies of chagasic patients with angiographically normal coronary arteries, by several scintigraphy methods, revealed myocardial perfusion abnormalities which may be caused by the microcirculatory derangements described in animals experimentally infected with the T. cruzi. Since hypoperfusion has been detected in regions with normal or mildly impaired wall motion, it is likely that the microvascular disturbances precede and may be a causative mechanism for the subsequent myocardial damage. We speculate that hibernating ventricular areas may occur in chagasic patients, on the basis of the evidence gathered from these studies. Recent investigations of chronic patients with Chagas' disease and chest pain showed attenuation of the vasomotor responses to physiological and pharmacological stimuli, in the epicardial coronary arteries.