Pulmonary atresia is a rare heart defect. In a normal heart, the blood flows in from the body to the right atrium. It then goes into the right ventricle. Next, the blood travels to the lungs through the pulmonary valve. There, it picks up fresh oxygen. The blood then returns to the left atrium and goes into the left ventricle. The blood moves out to the rest of the body.

With this defect, there is no pulmonary valve in the heart. Blood cannot flow into the pulmonary artery. This is the artery that brings blood to the lungs. Other heart problems, like a small right ventricle, may also be present.

Heart Chambers and Valves
heart anatomy
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Blood Flow Through the Heart
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A direct cause is not known. This defect develops while the baby is forming in the womb. The baby is born with the condition.