Valvular pulmonary stenosis is one of the more common forms of congenital heart disease and is due to a narrowing of the valve that is situated between the right ventricle and the pulmonary artery. Less commonly, the narrowing occurs within the right ventricle, a condition known as subpulmonary stenosis; when above the pulmonary arteries, it is referred to as pulmonary artery stenosis.
As the degree of pulmonary stenosis increases, the right ventricular muscle responds by developing excess thickness known as right ventricular hypertrophy. Valvular pulmonary stenosis can also be associated with enlargement of the pulmonary arteries, a communication across the atrial septum known as an ASD or PFO, or excess muscle below the valve.
Management of valvular pulmonary stenosis is determined by the degree of obstruction, which ranges from mild to severe. Patients with mild pulmonary stenosis typically have no cardiac symptoms and do not require intervention on the valve. Patients with moderate or more valvular pulmonary stenosis can generally be treated by balloon valvuloplasty, which replaced surgical valvotomy during the 1980s. If the valve leaflets cannot be opened with a balloon, then surgical repair is usually performed. This might be a valvotomy, in which the leaflets are incised to relieve the obstruction, or a pulmonary valve replacement.
Following successful balloon valvuloplasty or surgical valvotomy, it is common to see a leak in the pulmonary valve known as pulmonary regurgitation. Over time, this can lead to progressive enlargement of the right ventricle. In some of these patients, there may also be a leak in the tricuspid valve, known as tricuspid regurgitation. In the patients with marked right ventricular enlargement, pulmonary valve replacement is often advised to improve symptoms and decrease the size of the right ventricle. In some of these patients, the tricuspid valve may also require repair. We are currently studying which patients with this problem will benefit from pulmonary valve replacement.
Cardiac MRI is an important imaging tool in the assessment of these patients because it provides quantitative measurements of the right and left ventricular volumes not available with echocardiography. Some adults who have undergone repair of pulmonary stenosis may present with a cardiac arrhythmia, most commonly atrial flutter, which is usually amenable to catheter ablation.
In patients who develop severe obstruction within the body of the right ventricle, an entity known as double chambered right ventricle, surgical resection of the excess muscle bundles can be performed with effective relief of obstruction. In patients with obstruction within the pulmonary artery, careful study of the location, severity, and symptoms helps determine whether surgical or catheter-based procedures are indicated.