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Published on: December 11, 2016
Quantitative analysis of cardiac lesions in chronic canine chagasic cardiomyopathy
Marcelo Vidigal Caliari1, Raquel do Pilar Machado, Marta de Lana
1Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brasil. caliari@icb.ufmg.br
Insights
Chronic Chagasic Cardiopathy in dogs involves significant cardiac tissue changes. Fibrosis and adipose tissue replace cardiac muscle, leading to electrocardiographic alterations and potential heart dysfunction.
Area of Science:
- Veterinary Pathology
- Cardiology
- Parasitology
Background:
- Chronic Chagasic Cardiopathy (CCC) is characterized by cardiac lesions, electrocardiographic alterations, and impaired cardiac function.
- Experimental infection with Trypanosoma cruzi in dogs serves as a model to study CCC pathogenesis.
Purpose of the Study:
- To quantify cardiac muscle, connective tissue (fibrosis), and adipose tissue in the right atrium of dogs experimentally infected with Trypanosoma cruzi.
- To correlate histological findings with observed electrocardiographic changes and cardiac function abnormalities.
Main Methods:
- Computerized morphometrical analysis of atrial tissue from experimentally infected dogs.
- Histological examination to identify and quantify fibrosis, cardiac muscle, and adipose tissue.
- Electrocardiographic monitoring of infected dogs.
Main Results:
- All infected dogs exhibited chronic myocarditis with reduced cardiac muscle and replacement by fibrosis and adipose tissue.
- Dogs infected with Trypanosoma cruzi strain Be78 showed greater destruction of atrial cardiac muscle (34% muscle, 28% fibrosis, 38% adipose) compared to strain Be62 (50% muscle, 32% fibrosis, 18% adipose).
- Histological alterations, particularly fibrosis, were associated with electrocardiographic disturbances in 10 out of 11 dogs.
Conclusions:
- Trypanosoma cruzi infection induces significant atrial myocardial remodeling in dogs, characterized by fibrosis and adipose tissue infiltration.
- These histological changes are strongly linked to electrocardiographic abnormalities, mirroring findings in human CCC.
- The degree of cardiac muscle destruction and fibrosis varies with the infecting Trypanosoma cruzi strain, impacting cardiac function and potentially leading to arrhythmias and heart failure.
Abstract:
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.
