Double-Chambered Right Ventricle in Two Cats

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Double-chambered right ventricle (DCRV) is a congenital heart disease in which anomalous muscle bundles divide the RV into two chambers. We describe two cats that presented with right-sided congestive heart failure attributable to DCRV. Echocardiography revealed abnormal intracavity narrowing in the RV obstructing the pulmonary outflow with associated tricuspid regurgitation and severe right atrial enlargement. Histopathological examination showed right atrial enlargement, RV wall hypertrophy and myocardial fibrosis. Medical management of congestive heart failure was minimally effective in both cats, and a novel surgical approach was attempted in 1 cat. The present report demonstrates that DCRV can be diagnosed in cats by echocardiography and is associated with muscular and fibrous tissue in the endocardial region of the RV outflow tract.