Role of computed tomography angiography in the differentiation of feline truncus arteriosus communis from pulmonary atresia with ventricular septal defect

Two domestic shorthair cats, a 6-month-old castrated male and a 7-month-old intact female, were diagnosed with complex congenital heart disease. Transthoracic echocardiography in both cats revealed a dilated arterial trunk overriding the interventricular septum with a large ventricular septal defect. The pulmonary trunk and branch pulmonary arteries were not visible using standard echocardiographic views in either cat. The differential diagnosis for both cats included truncus arteriosus communis vs. pulmonary atresia with ventricular septal defect. Each cat underwent computed tomography angiography to determine the origin and extent of the pulmonary blood supply and to better define extra-cardiac anatomy. Computed tomography angiography led to a diagnosis of truncus arteriosus communis with unrestricted pulmonary blood flow in one cat, whereas the other cat was diagnosed with pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals serving as the primary source of pulmonary blood flow. Computed tomography angiography allowed for the ante mortem differentiation of truncus arteriosus communis from pulmonary atresia with ventricular septal defect in these two cats, leading to an accurate diagnosis and providing valuable information to therapeutic decision-making for each case.