Congenital Pulmonary Stenosis

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Pulmonary stenosis is a condition characterized by obstruction to blood flow from the right ventricle to the pulmonary artery.  This obstruction is caused by narrowing (stenosis) at one or more points from the right ventricle to the pulmonary artery.   Areas of potential narrowing include thickened muscle below the pulmonary valve, stenosis of the valve itself, or stenosis of the pulmonary artery above the valve. The most common form of pulmonary stenosis is obstruction at the valve itself, referred to as pulmonary valvar stenosis. 

Graphic Summary

The normal pulmonary valve consists of three thin and pliable valve leaflets. When the right ventricle ejects blood into the pulmonary artery, the normal pulmonary valve leaflets open easily and cause no obstruction to blood leaving the heart.  Most commonly with pulmonary valvar stenosis, the pulmonary valve leaflets are thickened and fused together along their separation lines (commissures). As a result, the leaflets become less pliable than normal, which contributes to the obstruction.   At times, the diameter of the pulmonary valve is small, or hypoplastic, resulting in obstruction. 

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When the pulmonary valve is obstructed, the right ventricle must work harder to eject blood into the pulmonary artery. To compensate for this additional workload, the muscle of the right ventricle gradually thickens.  The thicker right ventricular muscle, known as hypertrophy, is rarely a problem in itself, but instead is an indication that significant valve obstruction exists.

Children with pulmonary valvar stenosis are usually asymptomatic and in normal health.

A heart murmur is the most common sign detected by a physician indicating that a valve problem may be present. Children with mild-to-moderate degrees of pulmonary valve stenosis have easily detectable heart murmurs, but typically do not have any symptoms.

When the pulmonary valve is severely obstructed, especially in newborns with critical degrees of pulmonary stenosis, the right ventricle cannot eject sufficient blood flow to the pulmonary artery to maintain normal oxygen saturations.  In these instances, blue blood bypasses the right ventricle, flowing from the right atrium to left atrium, through the foramen ovale, a communication or "hole" between these two chambers that is normally present in newborns. Newborns with critical pulmonary stenosis therefore will have cyanosis (blue discoloration of the lips and nail beds) due to lower oxygen levels in their blood. 

A newborn with critical pulmonary stenosis presents an emergency situation that requires immediate treatment, either balloon dilation of the valve or surgery.

In an older child, severe pulmonary valve stenosis may cause easy fatigue or shortness of breath with physical exertion. Severe pulmonary valve stenosis rarely results in right ventricular failure or sudden death.

The diagnosis of pulmonary stenosis is usually first suspected because a physician detects a heart murmur.

The heart murmur of pulmonary stenosis is a turbulent noise caused by ejection of blood through the obstructed valve.

There is often an associated click sound when the thickened valve snaps to its open position. These sounds can be detected through careful examination of the heart by a physician well-trained in cardiac diagnosis.

Other testing may confirm the presence of pulmonary stenosis and help to document its severity.

The electrocardiogram is typically normal in the presence of mild pulmonary stenosis. With moderate-to-severe pulmonary stenosis the electrocardiogram may show enlargement of the right ventricle and thickening of its muscle.

The echocardiogram is the most important non-invasive test to detect and evaluate pulmonary valve stenosis. The echocardiogram accurately documents that the obstruction is present at the valve level, and Doppler studies are used to estimate the degree of obstruction.

The echocardiogram is also important to exclude other problems that may be associated with pulmonary stenosis, such as an atrial septal defect (ASD) or ventricular septal defect (VSD).

Cardiac catheterization is an invasive technique that enables physicians to accurately measure the degree of pulmonary stenosis that is present. During cardiac catheterization, pressure measurements are made above and below the valve to define the amount of obstruction and motion pictures are taken to visualize the pulmonary valve.

During the past 15 years, echocardiography has generally replaced cardiac catheterization for the detection and measurement of pulmonary valve stenosis. Cardiac catheterization is rarely needed to make the diagnosis but, instead, is typically done to perform a balloon dilation procedure described below.

Children with mild pulmonary valve stenosis rarely require treatment. Patients with mild pulmonary valve stenosis are healthy, can participate in all types of physical activities and sporting events, and lead normal lives.

Mild pulmonary valve stenosis in childhood rarely progresses after the first year of life. However, mild pulmonary stenosis in a young infant may progress to more severe degrees and requires careful follow-up.

Children with moderate-to-severe degrees of pulmonary stenosis require treatment, the timing of which is often elective.

The type of treatment required depends on the type of valve abnormality present. Most commonly, the pulmonary valve is of normal size, and the obstruction is due to fusion along the commissures or lines of valve leaflet opening.

This "typical" form of pulmonary valve stenosis responds very nicely to balloon dilation. Balloon dilation valvuloplasty is performed at the time of cardiac catheterization and does not require open-heart surgery. More typically, in older children, the procedure is performed electively on an outpatient basis.

In the newborn, balloon dilation for critical pulmonary valve stenosis can be a technically challenging procedure as these newborns can be critically ill and unstable.

Open-heart surgical procedures are required for more complex valves, where balloon dilation is not sufficient therapy. These valves may be obstructed by thick and dysplastic leaflet tissue (such as in patients with Noonan syndrome), and the diameter of the valve itself may be small in some cases.

For these conditions surgical pulmonary valvotomy (opening of the valve), partial valvectomy (removal of a portion of the leaflet), and possibly a transannular patch (patch from the right ventricle to pulmonary artery) may be required during the open-heart surgery repair.

Results of balloon dilation valvuloplasty for pulmonary stenosis have been excellent. This technique was developed in the mid-1980s, and significant experience has been gained in pediatric heart centers.

Importantly, balloon dilation cannot make an abnormal valve "normal."  Instead, the procedure decreases the degree of pulmonary valve obstruction from severe to mild in the large majority of patients.

For children and adolescents with "typical" pulmonary valve stenosis, a single balloon dilation procedure is usually the only therapy ever needed. It is rare that an older child will have return of significant pulmonary valve obstruction following a successful balloon dilation procedure.

Newborns and young infants with very severe pulmonary valvar obstruction will also have an excellent response to balloon dilation, unless the valve is underdeveloped in size.

However, recurrence of significant pulmonary stenosis does occur in approximately 5 percent to 10 percent of children within 10 years of intervention.  Occasionally, these patients may require a second balloon dilation, or an open-heart surgical procedure if the valve is small.

The long-term outcomes for open-heart surgery in patients with severe pulmonary valvar stenosis are also excellent.

Because balloon dilation is usually the only treatment necessary for most patients, open-heart surgery is generally only performed in patients with more complex forms of pulmonary valve obstruction.

However, patients with very thick valve leaflets or underdeveloped pulmonary valve sizes also have an outstanding long-term outcome following open-heart surgical repair. If there is no other associated heart disease, these children are expected to lead normal, active lives.

It is important that all children with pulmonary valve stenosis, even after very successful balloon dilation or open-heart surgery, be re-evaluated at regular intervals.

Long-term follow-up with evaluation by a qualified cardiologist is essential to helping provide the highest quality outcome for patients with pulmonary valve stenosis.

Adults who were born with pulmonary valve stenosis (PS) present several different scenarios. The mildest is that the PS is still mild in adult life. If so, it will not progress, and the patient does not require very frequent or expert attention.

Some adults with pulmonary stenosis will have had a balloon dilation or surgical opening of the valve. Most of these patients will have had an excellent result and may not need much care or attention as adults. A significant number of these patients will have a significant leak of the pulmonary valve. This can lead to excessive enlargement of the right heart and may eventually need pulmonary valve replacement.

A third group of adults has a moderate amount of pulmonary stenosis and is doing well. A certain proportion of these people will develop problems, and expert surveillance is recommended. Finally, PS can present as part of a more complex set of congenital heart anomalies. All such patients require lifelong, expert surveillance and management.

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Last Updated 12/2013