Pediatric aortic stenosis

Aortic stenosis is a heart defect that may be congenital (present at birth) or acquired (develop later in life). If the problem is congenital, then something occurred during the first 8 weeks of pregnancy to affect the development of the aortic valve.

The aortic valve is found between the left ventricle and the aorta. It has three leaflets that function like a one-way door, allowing blood to flow forward into the aorta, but not backward into the left ventricle. Aortic stenosis is the inability of the aortic valve to open completely.

With aortic stenosis, problems with the aortic valve make it harder for the leaflets to open and permit blood to flow forward from the left ventricle to the aorta. In children, these problems can include a valve that:

• Only has one or two leaflets instead of three
• Has leaflets that are partially fused together
• Has thick leaflets that do not open all the way
• Becomes damaged by rheumatic fever or bacterial endocarditis

Aortic stenosis may be present in varying degrees, classified according to how much obstruction to blood flow is present. A child with severe aortic stenosis will be quite ill, with major symptoms noted early in life. A child with mild aortic stenosis may have few symptoms, or perhaps none until later in adulthood. The degree of obstruction can become worse with time.

Congenital aortic stenosis occurs in 3 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 four times more often in boys than in girls.

What causes aortic stenosis in children?

Congenital aortic stenosis occurs due to improper development of the aortic valve in the first 8 weeks of fetal growth. It can be caused by a number of factors, though, most of the time, this heart defect occurs sporadically (by chance), with no apparent reason for its development.

Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families.

Acquired aortic stenosis may occur after a strep infection that progresses to rheumatic fever.

Why is aortic stenosis a concern?

Mild aortic stenosis may not cause any symptoms. Several problems may occur, however, when aortic stenosis is moderate to severe, including the following:

• The left ventricle has to work harder to try to move blood through the tight aortic valve. Eventually, the left ventricle is no longer able to handle the extra workload, and it fails to pump blood to the body efficiently.
• There is a higher than average chance of developing an infection in the lining of the heart or aorta known as bacterial endocarditis.
• The coronary arteries, which supply oxygen-rich (red) blood to the heart muscle, may not receive enough blood to meet the demands of the heart. 

What are aortic stenosis symptoms?

The following are the most common symptoms of aortic stenosis. However, each child may experience symptoms differently. Symptoms may include:

• Fatigue
• Dizziness with exertion
• Shortness of breath
• Irregular heartbeats or palpitations
• Chest pain

The symptoms of aortic stenosis may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.

How is aortic stenosis diagnosed?

Your child's physician may have heard a heart murmur during a physical examination, and referred your child to a pediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through the obstruction from the right ventricle to the pulmonary artery. Symptoms your child exhibits will also help with the diagnosis.

A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to your child's heart and lungs, and make other observations that help in the diagnosis. The location within the chest that the murmur is heard best, as well as the loudness and quality of the murmur (harsh, blowing, etc.) will give the cardiologist an initial idea of which heart problem your child may have. However, other tests are needed to help with the diagnosis, and may include the following:

• Chest x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
• Electrocardiogram (ECG or EKG) - a test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle stress.
• Echocardiogram (echo) - a procedure that 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 heart valves.
• Exercise electrocardiogram (ECG or EKG) - an exercise EKG is done to assess the heart's response to stress or exercise. The EKG is monitored while your child is exercising on a treadmill or stationary bike. An EKG measures the electrical activity of your child's heart.
• Cardiac catheterization - a cardiac catheterization is an invasive procedure that 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 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. Contrast dye is also injected to more clearly visualize the structures inside the heart.

Treatment for aortic stenosis

Specific treatment for aortic stenosis will be determined by your child's physician based on:

• Your child's age, overall health, and medical history
• Extent of the disease
• Your child's tolerance for specific medications, procedures, or therapies
• Expectations for the course of the disease
• Your opinion or preference

Aortic stenosis is treated with repair of the obstructed valve. Several options are currently available.

Some infants will be very sick, require care in the intensive care unit (ICU) prior to the procedure, and could possibly even need emergency repair of the aortic stenosis. Others, who are exhibiting few symptoms, will have the repair scheduled on a less urgent basis.

Children who do not require immediate repair in infancy may need to receive antibiotics to prevent an infection of the inner surfaces of the heart known as bacterial endocarditis prior to procedures such as a routine dental check-up and teeth cleaning. Other procedures may also increase the risk of the heart infection occurring. It is important that you inform all medical personnel that your child has aortic stenosis so they may determine if antibiotics are necessary prior to the procedure.

Activity may be limited in children who have moderate aortic stenosis prior to repair. For instance, competitive sports that require endurance may be restricted.

Repair options include the following:

• Balloon dilation or valvuloplasty - a cardiac catheterization procedure, 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.
• Valvotomy - surgical release of adhesions that are preventing the valve leaflets from opening properly.
• Aortic valve replacement - the aortic valve is replaced with a new mechanism. Replacement valve mechanisms fall into two categories: tissue (biological) valves, which include animal valves, and mechanical valves, which can be metal, plastic, or another artificial mechanism.
• Aortic homograft - a section of aorta from a tissue donor with its valve intact is used to replace the aortic valve and a section of the ascending aorta.
• Pulmonary homograft (Ross procedure) - a section of the child's own pulmonary artery with the valve intact is used to replace the aortic valve and a section of the aorta. A section of pulmonary artery from a tissue donor with its valve intact is used to replace the transplaced pulmonary artery. 

Postoperative care for your child

After surgery, your child will go to the intensive care unit (ICU). While your child is in the ICU, special equipment will be used to help him/her recover from surgery, and may include the following:

• Ventilator - a machine that helps your child breathe while he/she is under anesthesia during the operation. A small, plastic tube is guided into the windpipe and attached to the ventilator, which breathes for your child while he/she is too sleepy to breathe effectively on his/her own. Many children remain on the ventilator for a while after surgery so they can rest.
• Intravenous (IV) catheters - small, plastic tubes inserted through the skin into blood vessels to provide IV fluids and important medicines that help your child recover from the operation.
• Arterial line - a specialized IV placed in the wrist, or other area of the body where a pulse can be felt, that measures blood pressure continuously during surgery and while your child is in the ICU.
• Nasogastric (NG) tube - a small, flexible tube that keeps the stomach drained of acid and gas bubbles that may build up during surgery.
• Urinary catheter - a small, flexible tube that allows urine to drain out of the bladder and accurately measures how much urine the body makes, which helps determine how well the heart is functioning. After surgery, the heart will be a little weaker than it was before, and, therefore, the body may start to hold onto fluid, causing swelling and puffiness. Diuretics may be given to help the kidneys to remove excess fluid from the body.
• Chest tube - a drainage tube may be inserted to keep the chest free of blood that would otherwise accumulate after the incision is closed. Bleeding may occur for several hours, or even several days after surgery.
• Heart monitor - a machine that constantly displays a picture of your child's heart rhythm, and monitors heart rate, arterial blood pressure, and other values. 

Your child may need other equipment not mentioned here to provide support while in the ICU, or afterwards. The hospital staff will explain all of the necessary equipment to you.

Your child will be kept as comfortable as possible with several different medications; some which relieve pain and some which relieve anxiety. The staff will also be asking for your input as to how best to soothe and comfort your child.

After being discharged from the ICU, your child will recuperate on another hospital unit for a few days before going home. You will learn how to care for your child at home before your child is discharged. Your child may need to take medications for a while, and these will be explained to you. The staff will give you instructions regarding medications, activity limitations, and follow-up appointments before your child is discharged.

Long-term outlook after aortic stenosis surgical repair

Most children who have had an aortic stenosis surgical repair will live healthy lives. Activity levels, appetite, and growth should eventually return to normal.

As the child grows, a valve that was ballooned may once again become narrowed. If this happens, a second balloon procedure or operation may be necessary to repair aortic stenosis.

Your child's cardiologist may recommend that antibiotics be given to prevent bacterial endocarditis after discharge from the hospital.

Children who had an artificial valve replacement may need to take anticoagulants (blood thinners) to prevent blood clots from forming on the artificial valve surfaces.

Consult your child's physician regarding the specific outlook for your child.