The heart has four valves, these act as one way doors, they allow blood flow in one direction and prevent it from leaking backwards. The pulmonary valve guards the pulmonary artery which receives blood from the right ventricle and deliver it through the pulmonary blood vessels to the lungs.
Pulmonary stenosis is the second most common congenital heart disease.
Narrowing of the pulmonary valve will force the right ventricle to squeeze harder to be able to eject its blood contents into the pulmonary circulation. Pulmonary stenosis is classified as mild, moderate, severe and critical. Mild pulmonary stenosis usually stays mild and typically requires no medical therapy. Moderate pulmonary stenosis could progress to severe. Mild pulmonary stenosis does not require treatment.