In pulmonary stenosis, which is the second most common congenital heart disease, the heart’s pulmonary valve is thick and its opening is smaller than normal. As a result, blood cannot flow normally from the heart through the valve and to the lungs.
When the pulmonary valve is narrowed, the right ventricle (lower right chamber of the heart) tries to squeeze harder to push blood out into the pulmonary vessels. The extra effort will cause the right ventricle’s muscles to become bigger and thickened, making the ventricle stiffer and harder to fill. Initially, depending on how severely the valve is narrowed, enlarged right ventricle muscles may cause no symptoms or ill effects.
However, if the narrowing is severe, or if the narrowed valve places undue pressure on the heart over time, the right ventricle will become fatigued and may begin to fail under its workload. The inflow valve to the right ventricle, the tricuspid valve, may leak significantly due to the very high pressure generated in the ventricle. Individually or in combination, worsening stiffening of the ventricle or tricuspid valve leakage may place additional stress on the right upper chamber (atrium). If severe, this may result in edema (swelling of the abdomen, as well as the head, neck and extremities resulting from a build-up of fluid in the tissues).
Mild pulmonary stenosis usually is very stable over time and typically requires no medical therapy. Sometimes, as a child grows, this stenosis may improve on its own.
Moderate pulmonary stenosis could progress to severe. Both moderate and severe pulmonary stenosis require medical treatment, either with catheter-based balloon valvuloplasty or surgery.
In balloon valvuloplasty, which has become the standard of care to relieve pulmonary valve stenosis, a cardiologist inserts a balloon-tipped catheter (a thin, flexible tube) in a large vein in the groin and guides it through the arteries into the heart’s right ventricle. The catheter is placed across the narrow opening of the pulmonary valve and the balloon is inflated. As the balloon opens, it stretches the valve open, forcing it to become wider so more blood can flow through.
Balloon valvuloplasty works best if the stenosis is the result of fused valve leaflets, or cusps. If the valve leaflets are extremely thickened (dysplastic), balloon valvuloplasty may not be successful due to the rubbery nature of the valve. Surgical repair may then be necessary.
Improved blood flow through the pulmonary valve can be accomplished by surgically separating the valve’s leaflets or removing tissues that obstruct the valve.
Surgical repair of the valve requires opening the chest, stopping the heart and placing the patient on a heart-lung bypass machine to keep the blood circulating through the body during the procedure.