Studies of the coronary circulation in Chagas' heart disease

Abstract

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 free 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 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.

Pathogenesis of chronic Chagas cardiomyopathy: the role of coronary microvascular derangements

“…The remaining 60% of the segments with perfusion defects had normal or mildly reduced wall motion. Thus, this investigation clearly showed marked resting myocardial perfusion abnormalities preceding the appearance of any wall motion impairment 44 More recently, the use of magnetic resonance imaging (MRI) to examine patients with CCC has been reported 53,54 . In one study, 51 patients with CCC were investigated by MRI, including techniques of late contrast enhancement, for the detection of myocardial fi brosis.…”

“…However, other investigators showed no evidence of coronary artery spasm in any of 31 consecutive patients with Chagas' disease who exhibited precordial pain severe enough to warrant cardiac catheterization, despite the specifi c stimulus of the forced hyperventilation test Consistent with the experimental studies discussed above, impairment of endothelium-dependent coronary vasodilatation in response to acetylcholine has been reported in patients with Chagas' heart disease, but these patients had a preserved response to the non-endothelium-dependent effect of adenosine 43 . In another study, Chagas patients with angina that was atypical but severe enough to warrant coronary angiography had blunted vasomotor epicardial responses to hyperventilation and isosorbide dinitrate 44 . These combined fi ndings suggest that abnormal coronary fl ow regulation may be caused by endothelial and non-endothelial dysfunction in Chagas patients with chest pain and angiographically normal epicardial coronary arteries.…”

“…This alternative possibility is supported by the frequent occurrence of reverse redistribution defects predominating in LV regions with normal or mildly impaired wall motion in those studies. However, myocardial perfusion was also evaluated in 18 chronic Chagas' heart disease patients with recurrent chest pain that was severe enough to warrant coronary angiography using an exclusive perfusion tracer, 99m-technetium-labeled microspheres, injected into the LV cavity 44 . All patients presented normal epicardial coronary arteries.…”

Doenças cardiovasculares observadas durante o seguimento de um grupo de pacientes na forma indeterminada da doença de Chagas

“…Num estudo envolvendo 395 pacientes com IAM, 9,9% deles chagásicos, coronárias normais foram encontradas em 7,7% dos chagásicos e em 7,8% dos não chagásicos, não havendo diferenças também em relação às características clínicas, fatores de risco e evolução hospitalar nos dois grupos 37 . Em outro estudo, aterosclerose coronária esteve presente em 44% dos chagásicos e em 47% dos não chagásicos, não havendo também diferença estatisticamente significativa em relação à presença de IAM 38 .…”

I Diretriz Latino-Americana para o Diagnóstico e Tratamento da Cardiopatia Chagásica

“…Those microcirculatory changes are considered to amplify the inflammatory effects and to cause myocardial ischemia 24 . Several patients with CCC manifest angina-like symptoms, have electrocardiographic changes suggestive of ischemia and various myocardial perfusion defects 32,37 . Their epicardial coronary arteries are usually angiographically normal, but can react abnormally to vasodilating or vasoconstricting stimuli 37,38 .…”