The pulmonary valve is between the right ventricle and the pulmonary artery. It opens to allow blood to flow from the right ventricle to the lungs. A defective pulmonary valve that does not open properly is called pulmonary stenosis. That means the right ventricle must pump harder than normal to overcome the obstruction.

If the stenosis is severe, especially in babies, some cyanosis (blueness) may occur. Older children usually have no symptoms. Treatment is needed when the pressure in the right ventricle is higher than normal. In most children the obstruction can be relieved by a procedure called balloon valvuloplasty. In other patients, open-heart surgery may be needed. During surgery, the valve can usually be opened satisfactorily. The outlook after balloon valvuloplasty or surgery is favourable, but follow-up is required to determine if heart function returns to normal.

People with pulmonary stenosis, before and after treatment, are at risk for getting an infection of the valve (endocarditis). To help prevent this, they'll need to take antibiotics before certain dental and surgical procedures.