Experimental Trypanosoma cruzi cardiomyopathy in BALB/c mice. The potential role of intravascular platelet aggregation in its genesis.

In male BALB/c mice aged 5-6 weeks inoculated three times at intervals of 15 days with 1 X 10(7) epimastigote forms of the PF strain of Trypanosoma cruzi and challenged 30 days after the last inoculation with 2 X 10(4) trypomastigote forms of the Colombia strain of T cruzi (the mice were sacrificed 80-100 days after the challenge) a cardiomyopathy very similar to that observed in the chronic phase of Chagas' disease in man develops. The cardiac syndrome is characterized grossly by cardiomegaly with hypertrophy, dilatation of ventricular chambers, and thinning of the apex of the left ventricle (apical aneurysm) and microscopically by focal areas of myocytolytic necrosis and myocardial degeneration with an inflammatory response composed of mononuclear cells (predominantly macrophages and a few lymphocytes) with concurrent interstitial fibrosis and occasional myofibers containing pseudocysts. In addition, aggregated platelets and occlusive thrombi were found in small epicardial and intramyocardial vessels of infected mice as compared with controls. The potential role of intravascular platelet aggregation in the causation of focal myocardial necrosis and degeneration and apical aneurysm in experimental T cruzi cardiomyopathy in BALB/c mice is discussed.