To view the full text, please login as a subscribed user or purchase a subscription. Click here to view the full text on ScienceDirect. Figure 1 Echocardiographic images of a patent ductus arteriosus (PDA) demonstrating a left to right shunt. The PDA inserts into the pulmonary artery (PA) at point A, emerging from the aorta (Ao) at point B. Blue flow signifies normal forward flow through the pulmonary artery. Red flow signifies flow from the aorta to the pulmonary artery via the PDA.