Nonvisualization by aortography of patent ductus arteriosus associated with a large proximal left-to-right shunt.

Three cases are presented in which aortography failed to demonstrate the presence of a moderate-sized patent ductus arteriosus in association with a large proximal left to right shunt, but without other circumstances which would tend to diminish left to right shunt flow through the ductus. The ductus was not clinically apparent in any of these cases. Failure of expression of the distal lesion is most readily explained on hemodynamic grounds. A ductus was easily demonstrated in a fourth, otherwise similar, case. it is concluded that variability of expression makes it riaiy to exclude the possibility of a patent ductus arteriosus on the basis of a negative aortogram in the presence of a large proximal left to right shunt. It is possible that aorta-pulmonary artery indicator dilution curves would demonstrate the distal communication.