What is Aortic Stenosis?
The aortic heart valve is located between the left ventricle and the aorta. It functions as a one-way valve allowing oxygen-rich blood to flow out of the left ventricle to the rest of the body. It then closes to prevent blood from flowing back into the left ventricle. Aortic stenosis refers to the narrowing or obstruction of blood flow through the valve.
There are three types of aortic stenosis.
- Subvalvar aortic stenosis refers to a narrowing or obstruction below the valve.
- Valvar aortic stenosis refers to a narrowing or obstruction at the valve.
- Supravalvar aortic stenosis refers to 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 of the heart to the body.
How do we diagnose Aortic Stenosis?
Aortic Stenosis is usually diagnosed after a referral for a murmur. A murmur is a sound that the physician can hear when listening with a stethoscope. The sound is caused by the turbulence of the blood as it is pushed through the narrowing. If the valve is bicuspid, the physician may also hear a sound called 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 the heart must work very hard to pump enough blood to meet the body's needs, especially during exercise.
How do we treat Aortic Stenosis?
Usually the first line of treatment is a heart catheterization and attempt at 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 procedure called the "Ross procedure" involves replacing the aortic valve with the patient's own pulmonary valve. The pulmonary valve is then usually replaced with a homograft, which is a valve from a human, or occasionally a cow.
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