The pulmonary valve is located at the beginning of the pulmonary artery. It opens and closes to regulate blood flow into the pulmonary artery.
Stenosis means narrowing.
These abnormal leaflets do not open completely, causing a narrowing of the valve. The right ventricle works harder to pump blood past the narrow valve. With time, the extra work may stress the right ventricle causing it to enlarge. Pulmonary stenosis can vary from mild to severe. Children with mild pulmonary stenosis usually have no symptoms.