Aortic Valvar Stenosis (AS) in Children
Basics of Aortic Valvar Stenosis
Aortic stenosis is a heart defect that may be present at birth (“congenital”) or develop later in life (“acquired”). If a baby is born with AS, then something disrupted the aortic valve’s normal development during the first eight weeks of pregnancy.
Located between the left ventricle and aorta, the aortic valve has three leaflets that act like a one-way door, allowing blood to flow forward from the left ventricle into the aorta, but not backward into the left ventricle. With AS, however, the aortic valve is unable to open completely.
For children with AS, their aortic valve may have:
- Two leaflets (bicuspid aortic valve) instead of three, as in a normal heart
- Leaflets that are partially fused together
- Thick leaflets that do not open all the way
- Damage due to rheumatic fever or bacterial endocarditis
- An area above or below the valve that is narrowed (“supravalvar” or “subvalvar”)
Aortic stenosis occurs in varying degrees, from mild to severe, depending on how much blood flow is obstructed. Children with severe AS are quite ill and show major symptoms early in life. In contrast, children with mild AS may have few or no symptoms until later in adulthood. The obstruction can worsen with time.
Fast Facts of Aortic Valvar Stenosis
- Congenital aortic stenosis occurs in 4 percent to 6 percent of all children with congenital heart disease.
- Relatively few children are symptomatic in infancy, but the incidence of problems increases sharply in adulthood.
- Congenital aortic stenosis occurs three times more often in boys than in girls.
Causes of Aortic Valvar Stenosis
Abnormal development of the aortic valve during the first eight weeks of pregnancy causes congenital AS. While many factors can disrupt the valve’s normal development, the heart defect also occurs by chance (or sporadically) with no known cause.
Heredity plays a role in congenital heart defects like AS. Gene defects, chromosome abnormality or environmental exposure can cause heart problems to occur more often in certain families.
Aortic stenosis that develops later in life can be caused by a strep infection that progressed to rheumatic fever.
Symptoms of Aortic Valvar Stenosis
Each child may experience symptoms of AS differently, but the most common symptoms include:
- Dizziness with exertion
- Shortness of breath
- Irregular heartbeats or palpitations
- Chest pain
Because symptoms of aortic stenosis may resemble other medical conditions or heart problems, it’s important to always consult a child's physician for a diagnosis.
Health Problems Associated with Aortic Stenosis
Mild cases of aortic stenosis may cause no symptoms. But when AS is moderate to severe, the following health problems can arise:
- When the left ventricle is forced to work harder to try to move blood through the tight aortic valve, it eventually will no longer be able to handle the extra workload and fail to pump blood to the body efficiently.
- There is a higher than average chance that the aorta may become dilated (or enlarged), which increases the risk of an aneurysm or dissection of the aorta.
- There is a higher than average chance of developing bacterial endocarditis, an infection in the lining of the heart.
- The coronary arteries, which supply oxygen-rich (red) blood to the heart muscle, may not receive enough blood to meet the heart’s needs.
Tests, Procedures and Diagnosis of Aortic Stenosis
When a child's physician hears a heart murmur during a physical examination, the physician may refer the child to a pediatric cardiologist for a diagnosis. A pediatric cardiologist specializes in the diagnosis and treatment of congenital heart defects and heart problems that develop later in childhood. To diagnose a condition, a cardiologist performs a physical examination, listens to a child's 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 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). A test that records the electrical activity of the heart, it shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart muscle stress.
- Echocardiogram (or “echo”). This procedure evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and its valves.
- Exercise electrocardiogram (ECG or EKG). An exercise EKG assesses the heart's response to stress or exercise. An EKG measures the electrical activity of a child's heart while the child exercises on a treadmill or stationary bike.
- Cardiac MRI. This diagnostic procedure uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of the heart.
- 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 then guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, the pulmonary artery and aorta. In addition, contrast dye is injected to more clearly visualize the structures inside the heart.
Treatment for Aortic Valvar Stenosis in Children
A child’s physician determines the specific treatment for aortic stenosis based on:
- A child's age, overall health and medical history
- Severity of the disease
- A child's tolerance for specific medications, procedures or therapies
- Expectations for the course of the disease
- Parents’ opinions or preferences
Aortic stenosis can be treated by repairing the obstructed valve. Repair options include:
- Balloon dilation. A cardiac catheterization procedure during which a small, flexible tube (catheter) is inserted into a blood vessel in the groin and 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. After discharge from the hospital, children who have undergone balloon dilation need to take antibiotics.
- Valvotomy. This surgical procedure releases scar tissue within the aortic valve leaflets that is preventing the valve leaflets from opening properly.
- Aortic valve replacement. The aortic valve is replaced with a new valve, either a tissue (biological) valve or mechanical valve made from carbon fibers. Children who have undergone a valve replacement need to follow preventive antibiotic treatment prophylaxis throughout their lifetime. Children with a mechanical valve need lifelong treatment with Coumadin, a medication that thins the blood, to prevent clots from forming on the valve leaflets.
- Pulmonary autograft (Ross procedure). A section of the child's own pulmonary artery (with the pulmonary valve intact) is used to replace the aortic valve and a section of the ascending aorta. A section of pulmonary artery (with its valve intact) from a human donor is used to replace the transferred pulmonary artery.