Aortic injection study in a dog with a large patent ductus arteriosus and pulmonic regurgitation. Note the funnel shaped patent ductus arteriosus (PDA) and the large diameters of the aortic arch (AA) and the pulmonary trunk (PT).

Continued aortic injection study in the dog with a large patent ductus arteriosus. Dilation of the pulmonary trunk (PT) separates the pulmonic valve leaflets and allows pulmonic valve regurgitation (arrow) into the right ventricle (RV).