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. Then 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. Pulmonary valve
stenosis is a heart defect. This defect happens when the
pulmonary valve (the valve between the right ventricle and
pulmonary artery) is thickened or partially fused. When this
occurs, the valve does not work properly. Blood cannot move
efficiently from the heart to the lungs. The condition can be
mild to severe. Other heart defects may be present as well.
Pulmonary stenosis is a congenital defect. This means that the
baby is born with it. In most cases, it is not known exactly why
the heart develops abnormally. For many heart defects, the risk
factors are unclear. Risk factors for pulmonary