Assessing the severity of aortic valve stenosis
After confirming that you have aortic valve stenosis, your doctor will first ask, "Do you have symptoms?" If you have symptoms, your doctor will confirm that the symptoms are caused by aortic valve stenosis and that your stenosis is as severe as the presence of symptoms suggests. If you do not yet have symptoms, your doctor will want to assess the severity of the stenosis to see how serious your condition is.
Assessing severity is important, because you will probably not experience any symptoms until the stenosis becomes quite severe. You may live with mild or moderate aortic stenosis for many years. As a result, the only way for your doctor to monitor the progression of your condition is to monitor the aortic valve area and to watch for signs in the left ventricle that you are developing complications.
Your doctor should look first at the aortic valve area to assess the severity of stenosis. The doctor probably will allow some leeway when interpreting the valve area, given that your normal aortic valve size depends on body size. For example, 1.0 cm2 may be a sufficient valve opening for a smaller person, but the same measurement might mean severe stenosis in a large person.
How does the pressure gradient help doctors assess the severity of aortic valve stenosis?
If your left ventricle is still functioning normally, the doctor may also use your pressure gradient as an additional measure of the severity of stenosis. The pressure gradient is the difference in pressure between pressure buildup in the left ventricle and low pressure in the aorta. Severe aortic valve stenosis usually causes a high pressure gradient.
If the stenosis has begun to affect the function of your left ventricle, the pressure gradient may not be a reliable indicator of severity.
What is the importance of the left ventricle in assessing the severity of stenosis?
In addition to looking at the aortic valve itself, your doctor will evaluate your left ventricle, which pumps blood through a narrowed aortic valve to meet the needs of the body. There are two important measurements that your doctor will consider when evaluating the left ventricle:
- Size and thickness of the left ventricle. As aortic valve stenosis progresses, your left ventricle has to work harder to pump blood through a narrowing valve opening. Like any muscle, the walls of the left ventricle become thick from all of this work, a condition called hypertrophy.
- Function of the left ventricle. As your heart struggles over many years to pump blood through the narrowing valve, eventually your left ventricle will lose its ability to compensate for the pressure overload and will start to fail. The basic measurement of the function of the left ventricle is the ejection fraction, which is the percentage of blood in the filled ventricle that is pumped when the ventricle contracts. A low ejection fraction means that your left ventricle is losing or has lost its ability to pump enough blood to meet the body's needs.
As the stenosis becomes more severe, the walls of the left ventricles will get thicker and thicker. A greater degree of hypertrophy suggests more severe stenosis. Also, when your ventricle begins to fail, a low ejection fraction will also mean that your condition is getting worse.