Aortic stenosis is the narrowing or obstruction of blood flow through the aortic heart valve. This valve is located between the left ventricle and the aorta, the large vein that moves blood to the rest of the body. It allows oxygen-rich blood to flow out, and then closes to prevent blood from flowing back into the left ventricle.
There are three types of aortic stenosis.
- Subvalvar aortic stenosis is a narrowing or obstruction below the valve.
- Valvar aortic stenosis is a narrowing or obstruction at the valve.
- Supravalvar aortic stenosis is a narrowing or obstruction above the valve.
The most common cause of aortic stenosis is a bicuspid aortic valve. Normally, the aortic valve has three leaflets (or cusps) that open to allow blood to pass through. Some people are born with only two cusps (bicuspid valve). These valves do not open well and over time may become more narrow. When the valves do not open well or there is an obstruction, the heart has to work harder to move blood out to the body.
How we diagnose aortic stenosis
Aortic stenosis is usually diagnosed after a referral for a murmur, which is a sound a physician can hear when listening with a stethoscope. Blood turbulence causes this murmur as it is pushed through the narrowing valve. If the valve is bicuspid, the physician may also hear a "click," which occurs at the valve opening.
An echocardiogram can confirm the diagnosis and determine the amount of narrowing. Mild stenosis usually has no symptoms, but will require regular monitoring to assess any increased stenosis. Severe stenosis will require intervention, because it causes the heart to work much harder to pump enough blood to meet the body's needs, especially during exercise.
How we treat aortic stenosis
Usually the first line of treatment is a heart catheterization to attempt opening the valve, typically with a balloon. This treatment is usually not permanent. Surgery will be needed at a later point.
Surgical intervention involves opening the valve or replacing it with a mechanical valve. This usually requires the use of chronic medicines to thin the blood. Another intervention called the "Ross procedure" involves replacing the aortic valve with the patient's own pulmonary valve. This valve is then usually replaced with a homograft, which is a valve from a human, or occasionally a cow.
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