Right ventricular injection study in a dog with pulmonary hypertension and right-to-left patent ductus arteriosus. Note the contrast flow from the pulmonary trunk (PT) through the widely patent ductus arteriosus (PDA) directly into the descending aorta (DA) and back flow of contrast into the aortic arch (AA).

Continued right ventricular injection study in a dog with pulmonary hypertension and right-to-left patent ductus arteriosus. Note marked right ventricular infundibular hypertrophy (arrow) and tortuous pulmonary artery branches (PA). The right ventricular outflow tract opens widely in diastole but narrows significantly in systole.

Aortic injection study in the same dog with right to left patent ductus arteriosus and pulmonary hypertension shown in 026A. Note the negative contrast washout in the descending aorta (DA) by the entrance of non-opaque blood from the patent ductus arteriosus (PDA).

Continued aortic injection study in the same dog with right to left patent ductus arteriosus and pulmonary hypertension shown in 026A There is a little left-to-right flow from the aorta into the pulmonary artery (arrow) characteristic of a bidirectional PDA.