Pulmonary Valve Stenosis in Children
Basics of Pulmonary Valve Stenosis
Pulmonary valve stenosis is a heart valve disorder involving the pulmonary valve, which separates the right ventricle (lower right chamber of the heart) and the pulmonary artery. This congenital (present at birth) heart defect occurs due to abnormal development of the fetal heart during the first eight weeks of pregnancy.
The pulmonary valve has three leaflets that function like a one-way door, allowing blood to flow forward into the pulmonary artery, but not backward into the right ventricle. With pulmonary stenosis, problems with the pulmonary valve make it harder for the leaflets to open and permit blood to flow forward from the right ventricle to the lungs. In children, these problems may include:
- A valve that has leaflets that are partially fused together
- A valve that has thick leaflets that do not open all the way
- The area above or below the pulmonary valve is narrowed
There are four different types of pulmonary stenosis:
- Valvar pulmonary stenosis. The valve leaflets are thickened and/or narrowed
- Supravalvar pulmonary stenosis. The pulmonary artery just above the pulmonary valve is narrowed
- Subvalvar (infundibular) pulmonary stenosis. The muscle under the valve area is thickened, narrowing the outflow tract from the right ventricle
- Branch peripheral pulmonic stenosis. The right or left pulmonary artery is narrowed, or both may be narrowed
Pulmonary stenosis may occur in varying degrees. A child with severe pulmonary stenosis could be quite ill and suffer major symptoms early in life. Meanwhile, a child with mild pulmonary stenosis may have few or no symptoms, or perhaps none until adulthood. A moderate or severe degree of obstruction can worsen with time.
Fast Facts of Pulmonary Valve Stenosis
- Pulmonary stenosis is a component of half of all complex congenital heart defects.
- Pulmonary stenosis is the second most common congenital heart defect, comprising 5 percent to 10 percent of all cases.
Causes of Pulmonary Valve Stenosis
Congenital pulmonary stenosis occurs due to improper development of the pulmonary valve in the first eight weeks of pregnancy. Some congenital heart defects like pulmonary valve stenosis may have a genetic link, either occurring due to a gene defect, chromosome abnormality or environmental exposure, causing heart problems to be more frequent in certain families. But in the majority of cases, pulmonary valve stenosis occurs sporadically (by chance), with no clear cause.
Health Problems Associated with Pulmonary Valve Stenosis
When pulmonary stenosis is mild, it may cause no symptoms. But when the condition is moderate to severe, it can cause problems such as:
- The right ventricle must work harder to try to move blood through the tight pulmonary valve. Eventually, the right ventricle will be unable to handle the extra workload and fail to pump efficiently. Afterward, pressure builds up in the right atrium, followed by veins bringing blood back to the right side of the heart. Fluid retention and swelling may occur.
- A higher-than-average chance of developing an infection in the valves of the heart known as bacterial endocarditis.
Tests, Procedures and Diagnosis of Pulmonary Valve Stenosis
When a child's physician hears a heart murmur during a physical examination, the physician may refer the child to a pediatric cardiologist, who specializes in the diagnosis and treatment of congenital heart defects and heart problems that may develop later in childhood. To make a diagnosis, the cardiologist performs a physical examination, listens to the heart and lungs and makes other observations. Murmurs are evaluated on the basis of pitch, loudness and duration, which give the cardiologist an initial idea of which heart problem a child may have. Diagnostic testing for congenital heart disease varies by a child's age and clinical condition, and may include:
- Chest X-ray. This diagnostic test uses X-ray beams to produce digital images of internal tissues, bones and organs.
- Electrocardiogram (ECG or EKG). This test records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart muscle stress.
- Echocardiogram (or “echo”). This procedure uses sound waves recorded on an electronic sensor to produce a moving picture of the heart and its valves.
- Cardiac catheterization. This invasive procedure gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and gently guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. In addition, contrast dye is injected to more clearly visualize the structures inside the heart.
Treatment for Pulmonary Valve Stenosis
A child’s physician determines the specific treatment for pulmonary stenosis, based on:
- A child's age, overall health and medical history
- Severity of the condition
- A child's tolerance for specific medications, procedures or therapies
- Expectations for the course of the condition
- Parents’ opinions or preferences
While mild pulmonary stenosis often does not require treatment, moderate to severe cases are treated by repairing the obstructed valve. Repair options include:
- Balloon dilation or valvuloplasty. This interventional cardiac catheterization procedure is the most common treatment choice. During the procedure, a small, flexible tube (catheter) is inserted into a blood vessel in the groin, and gently guided to the inside of the heart. The tube has a deflated balloon in the tip. When the tube is placed in the narrowed valve, the balloon is inflated to stretch the area open. This procedure may be used for valvar pulmonary stenosis or branch types of pulmonary stenosis. After discharge from the hospital, a child will need to take antibiotics for a period of time.
- Valvotomy. This surgical procedure releases scar tissue within the aortic valve leaflets that are preventing the valve leaflets from opening properly.
- Valvectomy (with or without transannular patch). The surgical removal of the valve and widening of the outflow patch improves blood flow from the right ventricle into the pulmonary artery. After a child reaches adulthood, the pulmonary valve is generally replaced.
- Patch enlargement. Patches are used to enlarge the narrowed areas. In subvalvar pulmonary stenosis, an incision is made into the right ventricle and a patch is sewn into the cut edges of the right ventricle to enlarge the area where narrowing occurred. In supravalvar pulmonary stenosis, the narrowing occurs in the artery just beyond the pulmonary valve. Patches are sewn into this artery to enlarge its diameter and relieve the narrowing.
- Pulmonary valve replacement. This surgical procedure is often recommended after a child enters adulthood. A tissue valve (pig or human) may be used. Children who have undergone a valve replacement will need to follow antibiotic prophylaxis throughout their life.