Pulmonary stenosis is a narrowing of the pulmonary valve or the pulmonary artery (or its branches), which restricts blood flow from the right ventricle to the lungs. It is among the more common forms of congenital heart disease and can also occur in adults as a consequence of previous cardiac surgery.
The most common form is valvar pulmonary stenosis, where the pulmonary valve leaflets are thickened, fused, or malformed, reducing the size of the valve opening. Subvalvar stenosis (below the valve, within the right ventricular outflow tract) and supravalvar stenosis (above the valve, in the pulmonary artery) also occur, sometimes in combination. Pulmonary stenosis is a component of tetralogy of Fallot, the most common complex cyanotic congenital heart defect.
Mild to moderate pulmonary stenosis may cause no symptoms and remain stable for many years. Severe stenosis causes breathlessness on exertion, fatigue, and right ventricular hypertrophy (thickening of the right ventricle as it works against the obstruction). Without treatment, very severe stenosis can cause right heart failure. The diagnosis is confirmed by echocardiography, which measures the pressure gradient across the valve.
Significant pulmonary stenosis is usually treated by balloon pulmonary valvuloplasty, a catheter-based procedure in which a balloon is inflated across the narrowed valve to widen it. Surgical repair or pulmonary valve replacement is required for complex stenosis not amenable to balloon treatment. After repair, regular follow-up is recommended as the valve may re-narrow or develop regurgitation over time.
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