Lesions of the conduction system in the cat with cardiomyopathy.

Degeneration and fibrosis of the atrioventricular nodal tissue and left bundle branch, associated with cartilage of bone in the central fibrous body and fibrosis of the interventricular septal crest, were observed in 63 cats with cardiomyopathy. The cardiac lesions consisted of endocardial and myocardial fibrosis or organized endomyocarditis. Electrocardiographic, radiographic, angiocardiography, and hemodynamic changes were also observed in the cats.