**1. Introduction**

The ductus arteriosus is a fetal vascular structure that connects the descending aorta to the pulmonary artery (PA). It develops from the left sixth aortic arch in the embryo by the sixth week, directing blood flow returning to the heart away from the lungs. Soon after birth, the ductus arteriosus should begin to close spontaneously in response to environmental changes [1]. Patent ductus arteriosus (PDA) can be expected in all infants immediately after birth but may become pathologic if closure fails to occur within the first few days. Non-pathologic PDAs may occur in infants with cyanotic heart disease and increased pulmonary vascular resistance.
