Double outlet right ventricle in a calf

Abstract

Double outlet right ventricle is a conotruncal malformation where both great arteries (aorta and pulmonary trunk) arise from the right ventricle. A 2-month-old Holstein calf was slaughtered due to severe respiratory distress. At necropsy, the heart was enlarged, globose, and had ventricular and atrial septal defects. The only outlet for the left ventricle was a large ventricular septal defect located at 6 cm distance from the heart apex and involved atrial septum too. The right ventricle was enlarged and markedly thickened with a left to right free wall ratio of 2.5:2 and prominent papillary muscles. The aorta arose from the right ventricular infundibulum adjacent to pulmonary trunk. Two valvular hematomas were observed on the edge of the right atrioventricular valve. The lungs were rubbery with ecchymotic and petechial hemorrhages and did not collapse after removing from thoracic cavity. Enhanced lobular pattern was evident on both the capsular and cut surfaces of the liver. Histopathological examination of the lungs revealed thickening of alveolar septa, hemorrhages, and infiltration of hemosiderophages within alveoli. Periportal hepatocellular fatty changes, substitution of centrilobular and midzonal hepatocytes by red blood cells, and dilation of midzonal and periportal sinusoids were seen in the liver. To our knowledge, this particular combination of cardiac defects has not been previously described in domestic animals and the pathological lesions observed in the calf may be resulted as a sequel to left–right blood shunting and heart failure.