Pulmonary supravalvular stenosis is a condition where narrowing occurs above the valve between the heart and the vessel carrying blood to the lungs, in the lung artery itself.
When the heart squeezes, the right ventricle (the lower right chamber) contracts and pushes blood out into the pulmonary artery (the artery that takes blood to the lungs). The pulmonary, or pulmonic, valve sits on the way out of the heart between the right ventricle and the main pulmonary artery to prevent blood from leaking back into the heart between beats. A normal pulmonary valve is made up of three thin leaflets.
In pulmonary supravalvular stenosis, the leaflets are fused or are too thick, or there are fewer than three. As a result, the pulmonary valve is too narrow, and the heart has to work harder to pump enough blood to the body. Treatment usually involves surgical operations.