Congestive heart failure in a young cat with excessive moderator bands (false tendons) in the left ventricle.

Left ventricular false tendons are fibrous or fibromuscular bands that transverse the ventricular cavity and have no attachment to the mitral valve in many species. In cats it is considered a congenital defect that is rarely related to clinical disease and death in adult cats. A 45 days-old mixed breed cat had a history of inappetence since birth. At the physical exam the patient was lethargic and presented restrictive dyspnoea. At necropsy, there were marked ascites, hydrothorax, hepatomegaly with enhanced lobular pattern (nutmeg liver), and the lungs were markedly diminished (compressive pulmonary atelectasis). The heart was enlarged due to marked dilation of the cardiac chambers. Moreover, multiple slightly whitish and irregular cord-like structures were connecting the posterior papillary muscle to the interventricular septum (excessive moderator bands/left ventricular false tendons) at the left ventricle. Microscopically, these structures were characterized by a marked proliferation of fibrous connective tissue intermixed with Purkinje cells and well-differentiated cardiomyocytes lined by a single layer of endocardium. This study described a case of excessive moderator bands (left ventricular false tendons) in a young cat associated with congestive heart failure and death. [ABSTRACT FROM AUTHOR]