Aortic Stenosis

Aortic Stenosis

Animation available at: http://www.childrens-heart-fed.com/resources__and__info/heart_conditions/aortic_stenosis

Aortic Valve Stenosis

When a heart is functioning normally, blood is pumped through its four chambers with the help of a series of heart valves.

These valves open and close in a way that allows blood to flow only one way. The aortic valve allows oxygen-rich (red) blood to flow from the left pumping chamber of the heart, called the left ventricle, to the body's main artery, called the aorta. The aorta sends oxygen-rich blood throughout the body.

The aortic valve 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. Aortic stenosis may be congenital (present at birth) or acquired (develop later in life).
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 two leaflets instead of three (bicuspid aortic valve)
  
• 
  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.

How common is it?

Congenital aortic stenosis occurs in 3 to 6 percent of all children with congenital heart disease. Relatively few children show sign of aortic stenosis 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?

Congenital aortic stenosis occurs due to improper development of the aortic valve in the first 8 weeks of fetal growth. 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. Rheumatic fever is a disease that is now much less common in the United States than it was several decades ago. It is an inflammatory disease caused by certain rare forms of strep bacteria that can cause inflammation and scarring of the heart valves.
Why is aortic stenosis a concern?

Mild aortic stenosis may not cause any symptoms. However, there is a higher than average chance of developing an infection on the abnormal aortic valve known as bacterial endocarditis.

Also, when aortic stenosis is moderate to severe, the left ventricle has to work harder to get blood through the tight aortic valve to the body. In response, the left ventricle becomes thicker and pumps blood at a higher pressure. Over time, this extra workload can cause damage to the left ventricle while it fails to pump blood to the body efficiently.
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.
In addition, regurgitation, which means leaking of blood backwards through the valve, is common in patients with aortic stenosis. Normally this would happen after interventions to help fix the obstruction of the valve have been done. When severe, this can complicate aortic stenosis and result in additional problems for the left ventricle.
What are the symptoms of 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
  
• 
  how your child's doctor expects the disease may progress
  
• 
  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 show 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 and valves 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 - 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 across the narrowed valve, the balloon is inflated to stretch the area open.
  
• 
  surgical repair - the treatment of aortic valve stenosis in most centers is now balloon dilation. If this is unsuccessful, i.e. the pressure gradient cannot be reduced or the pressure gradient is very much reduced but leakage of the valve is induced (regurgitation), it may be necessary to undertake surgical repair of the aortic valve. If this is not successful the valve must be replaced.
  

What is the 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.

Individuals who had a mechanical valve replacement may need to take anticoagulants (blood thinners) to prevent blood clots from forming on the artificial valve surfaces. Regular monitoring of the blood's clotting status is very important in maintaining the most appropriate dose of anticoagulants.

Initial valve replacement is often performed using a tissue valve to avoid the need for anticoagulation, especially for females of childbearing age. Anticoagulation during pregnancy is very difficult to manage, and requires special treatment.

Repeat valve replacement is not uncommon during the lifespan. In addition, blood pressure should be closely monitored and managed.

Source: Children’s Hospital, Boston Cardiology Website, Accessible at: http://www.childrenshospital.org/az/Site481/mainpageS481P0.html