Cardiac Truncus Arteriosus in an Eastern Black Rhinoceros (Diceros bicornis michaeli)

Common arterial trunk in a cat: a high-resolution morphological analysis with micro-computed tomography

A 6-month-old female cat presented with respiratory distress. Physical examination showed a grade 5/6 holosystolic murmur with prominent precordial impulse over the left cranial chest wall. Echocardiography revealed bilateral hypertrophy of the ventricular walls, a dilated ascending aorta overriding the interventricular septum, a membranous ventricular septal defect and no obvious pulmonary trunk or pulmonary artery branches. Turbulent blood flow was detected around the ventricular septal defect and ascending aorta. Follow-up assessment, 12 months later, revealed marked and progressive biatrial dilation and biventricular hypertrophy. Four months after that, the cat died of severe congestive heart failure. To make a definitive postmortem diagnosis, we performed contrast enhanced micro-computed tomography (CT) on the ex vivo heart with micron-scale spatial resolution imaging and three-dimensional reconstruction. Micro-computed tomography analysis confirmed a common arterial trunk that bifurcated into the left pulmonary artery and aorta 5-mm distally from the truncal valve. The pulmonary trunk was absent. Slightly distal to the first branching, the common arterial trunk further branched into the right pulmonary artery and ascending aorta, indicating the aortic dominant form. Although CT angiography would be a preferred imaging modality for living animals, micro-computed tomography is a valuable tool for the ex vivo diagnosis of complex cardiac anomaly, such as presented in this cat.