Quantitative analysis of cardiac lesions in chronic canine chagasic cardiomyopathy.
Lesions observed in chronic chagasic cardiopathy frequently produce electrocardiographic alterations and affect cardiac function. Through a computerized morphometrical analysis we quantified the areas occupied by cardiac muscle, connective and adipose tissues in the right atrium of dogs experimentally infected with Trypanosoma cruzi. All of the infected dogs showed chronic myocarditis with variable reduction levels of cardiac muscle, fibrosis and adipose tissue replacement. In the atrial myocardium of dogs infected with Be78 and Be62 cardiac muscle represented 34 and 50%, fibrosis 28 and 32% and adipose tissue 38 and 18%, respectively. The fibrosis observed was both diffuse and focal and mostly intrafascicular, either partially or completely interrupting the path of muscle bundles. Such histological alterations probably contributed to the appearance of electrocardiographic disturbances verified in 10 out 11 dogs which are also common in human chronic chagasic cardiopathy. Fibrosis was the most important microscopic occurrence found since it produces rearrangements of collagen fibers in relation to myocardiocytes which causes changes in anatomical physiognomy and mechanical behavior of the myocardium. These abnormalities can contribute to the appearance of cardiac malfunction, arrythmias and congestive cardiac insufficiency as observed in two of the analyzed dogs. Strain Be78 caused destruction of atrial cardiac muscle higher than that induced by strain Be62.
Caliari
Marcelo Vidigal
MV
Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brasil. caliari@icb.ufmg.br
do Pilar Machado
Raquel
R
de Lana
Marta
M
Caja
Rosângela Aparecida França
RA
Carneiro
Cláudia Martins
CM
Bahia
Maria Teresinha
MT
dos Santos
César Augusto Bueno
CA
Magalhaes
Gustavo Albergaria
GA
Sampaio
Ivan Barbosa Machado
IB
Tafuri
Washington Luiz
WL
D000273:Adipose Tissue / Q000469:parasitology; D000818:Animals; D002598:Chagas Cardiomyopathy / Q000469:parasitology / Q000473:pathology*; D002908:Chronic Disease; D003238:Connective Tissue / Q000469:parasitology; D004195:Disease Models, Animal; D004285:Dogs; D009205:Myocarditis / Q000469:parasitology / Q000473:pathology*; D009206:Myocardium / Q000473:pathology; D014349:Trypanosoma cruzi / Q000472:pathogenicity*