Which condition is dependent on the patent ductus arteriosus?

The condition that is dependent on the patent ductus arteriosus (PDA) is transposition of the great vessels. In this congenital heart defect, the aorta arises from the right ventricle, and the pulmonary artery arises from the left ventricle, creating two separate circulations that do not communicate. This results in severe hypoxemia unless there is mixing of blood, which can occur if there is a PDA or other shunt such as an atrial septal defect or ventricular septal defect.

In infants with transposition of the great vessels, the PDA plays a crucial role in allowing blood to mix between the systemic and pulmonary circulations. If the PDA closes, it can lead to critical cyanosis and rapidly deteriorating clinical status because the systemic blood does not get adequately oxygenated. Therefore, the presence of a PDA significantly impacts survival and stabilization in these patients until surgical intervention can be performed.

Other conditions listed, such as ventricular septal defect, tricuspid regurgitation, and atrial septal defect, do not rely on a patent ductus arteriosus for their pathophysiology or management, hence distinguishing transposition of the great vessels as the correct choice.