An absent pulmonary valve is a rare heart defect.

In a normal heart, blood flows from the body into the right atrium and on to the right ventricle. Blood is then pumped out of the heart through the pulmonary artery to the lungs. The blood picks up fresh oxygen in the lungs. The blood returns to the left atrium of the heart and goes into the left ventricle. There it is pumped out through the aorta to deliver oxygen-rich blood to the rest of the body.

Heart Chambers and Valves
heart anatomy
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Blood Flow Through the Heart
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With this defect, the pulmonary valve does not develop properly. The opening where the valve should be is also narrowed. The defect causes the blood moving from the right ventricle to the arteries leading to the lungs to build up. This build-up causes swelling of these arteries that can put pressure on the air passages in the lungs.

The condition can be mild to severe. It usually occurs with other heart defects, like tetralogy of Fallot (a group of heart defects), or with an opening between the ventricles called a ventricular septal defect.

Ventricular Septal Defect
Ventral septal defect
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Absent pulmonary valve is a congenital defect. This means that the baby is born with it. It is not known exactly why some babies’ hearts develop abnormally.