Definition of Pulmonary valve stenosis:

Pulmonary valve stenosis is a condition in which the flow of blood from the heart (right ventricle, or lower chamber) is blocked at the valve that separates the heart from the pulmonary artery (pulmonic valve). This narrowing is usually present at birth (congenital).

Causes, incidence, and risk factors:

Pulmonary valve stenosis is most often caused by a problem that occurs when the unborn baby (fetus) is developing. The cause is unknown, but genetics may play a role.

Narrowing that occurs in the pulmonary valve is called pulmonary valve stenosis. Narrowing that occurs below the pulmonary valve is called subvalvar pulmonary stenosis. Another form of the condition, supravalvar pulmonary stenosis, is when narrowing occurs above the main pulmonary valve.

The defect may occur alone. However, it can also occur with other heart defects. The condition can be mild or severe. It occurs rarely, in only about 10% of patients with congenital heart disease.

Pulmonary stenosis can also occur later in life as a result of conditions that cause damage or scarring of the heart valves. These include rheumatic fever, endocarditis, and other disorders.