Absence of left ventricular dysfunction during acute chagasic myocarditis in the rhesus monkey

Recent studies suggest that intracellular Trypanosoma cruzi invasion with release of intracellular myocardial antigens during T. cruzi infection is crucial to the pathogenesis of chronic chagasic myocarditis. However, in areas endemic for Chagas' disease, the incidence of clinical acute chagasic myocarditis has been reported to be low among infected individuals, while the incidence of chronic chagasic myocarditis is relatively high. Thus, either acute chagasic myocarditis rarely complicates T. cruzi infection and is not important to the pathogenesis of chronic chagasic myocarditis, or acute chagasic myocarditis rarely impairs left ventricular function and therefore causes no symptoms. To investigate this question we innoculated T. cruzi from a human patient with Chagas' disease into the subconjuntivae of six rhesus monkeys (7.5 X 10(3) parasites each). Parasitemia was monitored and weekly two-dimensional echocardiograms (for determination of end-diastolic and fractional change in area, EDA and FCA) were obtained to quantify global left ventricular function for 10 weeks. Regional left ventricular function was assessed by visual analysis of two-dimensional echocardiograms. Extent of acute myocarditis was established at autopsy. All monkeys had the Romaña sign and detectable parasitemia in the second week. Parasitemia rose in all by the ninth week (mean = 1.8 X 10(5) parasites/ml); four monkeys lost weight (mean = -12%), three died, and three were killed. Two-dimensional echocardiographic EDA and FCA remained unchanged from control to the last study within 12 hr of death (EDA = 2.6 +/- 0.9 to 2.7 +/- 1.0 cm2, FCA = 80 +/- 6.8 to 74 +/- 7.6%, NS). Furthermore, regional left ventricular function remained unchanged throughout the period of study.(ABSTRACT TRUNCATED AT 250 WORDS)