Pulmonary atresia with ventricular septal defect

Pulmonary atresia with ventricular septal defect (PA-VSD), also known as pulmonary atresia with VSD or tetralogy of Fallot with pulmonary atresia, is a complex congenital heart defect in which the pulmonary valve fails to form properly, completely blocking blood flow from the right ventricle to the pulmonary artery, combined with a hole between the two lower chambers of the heart (ventricular septal defect). This condition is considered the most severe form of tetralogy of Fallot. Because blood cannot travel through the normal pulmonary artery pathway to the lungs, the body relies on alternative blood vessels called major aortopulmonary collateral arteries (MAPCAs) or a patent ductus arteriosus to supply blood to the lungs for oxygenation. The anatomy of the pulmonary blood supply is highly variable among affected individuals. Infants with PA-VSD typically present shortly after birth with cyanosis (bluish discoloration of the skin due to low oxygen levels), rapid breathing, difficulty feeding, and failure to thrive. The severity of symptoms depends largely on the source and adequacy of pulmonary blood flow. Some patients may have well-developed native pulmonary arteries, while others rely entirely on MAPCAs, which can lead to uneven blood flow distribution to the lungs. Without treatment, the condition is life-threatening. Treatment is surgical and often requires a staged approach. Initial management in neonates may include prostaglandin infusion to maintain ductal patency and ensure adequate pulmonary blood flow. Surgical interventions include placement of a modified Blalock-Taussig shunt, unifocalization of MAPCAs (connecting collateral vessels to create a unified pulmonary blood supply), VSD closure, and placement of a right ventricle-to-pulmonary artery conduit. The specific surgical strategy depends on the individual anatomy of the pulmonary arteries and collateral vessels. Long-term follow-up is essential, as patients often require multiple surgeries or catheter-based interventions throughout their lives, including conduit replacements. Outcomes have improved significantly with advances in surgical techniques, though the prognosis varies depending on the complexity of the pulmonary vascular anatomy.

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