What other abnormality must be present with pulmonary atresia?

• A. VSD
• B. ASD
• C. PDA
• D. Coarctation

Answer: (C)

Pulmonary atresia blocks the flow from the right ventricle to the pulmonary arteries, so the lungs won’t get blood after birth unless there is another route to the pulmonary circulation. The ductus arteriosus, a fetal connection between the aorta and the pulmonary arteries, must remain open to supply the lungs in this condition. Keeping the ductus patent (often with prostaglandin E1) provides the essential lung blood flow until a surgical repair or alternative shunt is established. While a ventricular septal defect is common and affects the exact circulation, it is not the mechanism that ensures pulmonary perfusion in this scenario. An ASD or coarctation does not by itself supply the pulmonary circulation.