Patent ductus arteriosus (PDA) is the persistent opening of the ductus arteriosus after birth, allowing blood to flow from the aorta to the pulmonary artery. It is common in preterm infants under 1.5kg. Untreated PDA can lead to pulmonary overload and congestive heart failure. Symptoms include tachypnea, bounding pulse, and frequent respiratory infections. Diagnosis involves physical exam, chest x-ray, echocardiogram, and cardiac catheterization. Treatment options include medications to close the ductus like indomethacin or surgery to ligate the ductus if medications fail or for symptomatic patients. Complications can include congestive heart failure, infective end