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:
a) only has two leaflets instead of three (bicuspid aortic valve)
b) has leaflets that are partially fused together
c) has thick leaflets that do not open all the way 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.
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