Pathology of complete atrioventricular block in chronic chagas' myocarditis

Abstract

Sclero-atrophy, fibrosis, vascular ectasia, phlebosclerosis and mild non-specific chronic inflammatory changes were observed in variable location and proportion involving the atrioventricular conducting tissue of the heart in five human cases of chronic Chagas' myocarditis associated with complete atrioventricular block. One case presented complete destruction of the A-V conduction system. In three cases the lesions were disseminated all along the conducting tissue but did not cause anywhere a complete disruption in the continuity of the system. The distal portion of the bundle branches were the most damaged sector of the system, exceptfor the fasciculi of the posterior division of the left bundle branch which were relatively preserved. One case exhibited bilateral sclero-atrophy of the bundle branches as the main change; and another showed early and mild fibrocalcific damage of the penetrating portion of the His bundle. The A-V node appeared as the least involved part of the conducting system in the cases studied. Demonstration of the lesions in this series of cases seems important because: a) it reveals that complete atrioventriculr block in chronic Chagas' disease results from disseminated lesions and not from focal disruptive change as has been commonly observed in cases of other etiologies; b) it shows that chronic inflammation can produce at the end variable and widespread vascular, degenerative andfibrotic alterations within the conducting tissue of the heart, which may lead to its total destruction.

Quantitative analysis of cardiac lesions in chronic canine chagasic cardiomyopathy

“…A significant replacement of the destroyed myocardium by adipose tissue was also verified which had also been described by others 2 . In all chagasic dogs an increase of adipose tissue was observed.…”

Interrelationship between adipocytes and fibroblasts during acute damage to the subcutaneous adipose tissue of rats: an ultrastructural study

“…Evidence of fatty metaplasia or fatty infiltration in connective tissues is abundant in the literature. Fatty tissue can be seen infiltrating the right ventricular myocardium in obese persons (14), can replace a large part of the pancreatic interstitial tissue (lypomatosis) (15), can fill the lumen of the fibrosed appendix or replace parts of the conducting tissue of the heart in Chagas disease (16). Infiltrative growth is a prerogative of transformed (neoplastic) cells.…”