Pulmonary Stenosis

Definition and Morphology

Pulmonary valvular stenosis is usually an isolated congenital anomaly and occurs in 7% to 12% of patients with congenital heart disease. It can sometimes be associated with other congenital heart defects such as atrial septal defect or peripheral pulmonary artery stenosis. It is the most common form of right-sided obstruction and results from the fusion of the valve leaflets. The pulmonary valve appears conical or dome-shaped with a narrow opening at its apex; the leaflets are fused, and in adults calcification may be present. The number of leaflets may vary from one to four. The valve is sometimes called dysplastic when the leaflets are very thick, but there is no fusion of the cusps, generally a component of Noonan syndrome. Pulmonary valve stenosis is rarely due to rheumatic inflammation, carcinoid involvement, compressive tumors, or infective endocarditis. Pulmonary stenosis may be associated with various genetic or chromosomal disorders, the most common being the RASopathies (Noonan, Leopard, and Costello syndromes), but also Williams and Alagille syndromes. Mutations in GATA4 have been associated with pulmonary valve stenosis. The functional consequence of pulmonary stenosis is obstruction of the ejection of blood from the right ventricle leading to an increase in right ventricular pressure. Right ventricular output is maintained by the development of right ventricular hypertrophy, which may sustain a large pressure gradient across the pulmonary valve for many years without symptoms, the development of right ventricular dilation, or a reduction in cardiac output.

Early Presentation and Management

Severe pulmonary stenosis in neonates is frequently associated with a hypoplastic right ventricular cavity and may be fatal without rapid intervention. The main clinical symptom is cyanosis due to right-to-left shunting through a patent foramen ovale caused by increased right-sided pressures. The diagnosis of severe pulmonary valvular stenosis can be made by echocardiography in fetal life or in the neonatal unit. Balloon dilation of the pulmonary valve is the procedure of choice to relieve the obstruction. Pulmonary valvotomy or systemic-to-pulmonary arterial shunt may be necessary if there is underdevelopment of the right ventricle, the pulmonary valve annulus, or the pulmonary artery branches.

Clinical presentation in childhood depends on the severity of the obstruction and the degree of hypoplasia of the right ventricle. Most children are asymptomatic, and pulmonary stenosis is often discovered during routine examination. When symptoms are present, children experience exertional symptoms: dyspnea, fatigue, mild cyanosis, chest pain, or syncope. Mild pulmonary stenosis has a favorable course. Relief of the obstruction is indicated for children with moderate to severe stenosis, even in the absence of symptoms.

Late Outcome

Late Complications

Obstruction to the ejection of blood from the right ventricle leads to an increase in right-sided pressures and to secondary right ventricular hypertrophy. The right ventricular hypertrophy may be particularly noticeable in the infundibular region, producing dynamic narrowing of the outflow tract and contributing to an increase in the degree of obstruction. With time, such patients may present with decreased exercise tolerance, dyspnea, and signs of right ventricular failure. Right ventricular failure is the most common mode of death in unoperated patients with moderate to severe obstruction. Supraventricular arrhythmias (atrial fibrillation or flutter) may precipitate symptoms of right ventricular failure. Bacterial endocarditis is a rare complication. Complications after pulmonary valvotomy (surgical or balloon) include pulmonary regurgitation with right ventricular dilation, residual valvular or infundibular obstruction, supraventricular or ventricular arrhythmias, and sudden death.

Outpatient Assessment