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Aortic Stenosis
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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:
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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
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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:
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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 checkup 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.
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Repair options include the following:
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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
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