**5.1 Macroscopic features**

The most striking characteristic of CCC is enlargement of heart with variable degrees of dilatation of chambers (Andrade, 1985) (Figure 4A). In autopsy series, hearts were overweighted (Andrade, 1985, Baroldi, et al., 1997, Bestetti, et al., 1993, Lopes, et al., 1981) compared with indeterminate chagasic patients and non-chagasic subjects. Marked cardiomegalies reached up to 500 grams. Right ventricle (RV) and atrium (RA) were generally more compromised than left chambers, being RV the most dilated in one paper (Laranja, et al., 1956) but RA was in other (Andrade, 1985).

A second remarkable feature is the thinning of the left ventricular apical wall, resulting in apical aneurysm, a very characteristic lesion in CCC (Figure 4B) (Moia, et al., 1955).

Other lesions described are flattening of the papillary muscles and a marked subendocardial sclerosis, parietal and/or aneurismal thrombosis and fibrotic plaques in pericardium (Milei, et al., 1996a, Milei, et al., 1991b, Storino & Milei, 1994).

Pathogenesis and Pathology of Chagas' Chronic Myocarditis 135

Fig. 5. A. Extensive mononuclear infiltrates, myocytes loss, and subendocardial fibrosis. Hematoxylin and eosin stain, X25. B. Atrophic myocardial fibres (red) separated by thick bands of fibrous tissue (blue). Mallory trichrome, X 25. C. Bifurcating His bundle showing

intramyocardial and surrounded by connective tissue. Mallory trichrome, X25. A and C

severe fibrosis at the left branch (between arrows). The right branch (asterisk) is

from Milei, 1996a. B from Milei, 2008.

Fig. 4. A. High grade heart dilatation. Thining of the apical wall of the left ventricle (white arrow) and cavitary thrombus (black arrow). B. Characteristic apical aneurysm. A from Milei, et al., 1996b, B from Milei, et al., 2008.
