Determining the severity of mitral valve stenosis
After your doctor has determined that you have mitral valve stenosis, he or she will determine its severity in order to choose the correct treatment. This is done by assessing the size of the valve opening and its pressure gradient.
Size of valve opening
Mitral valve stenosis occurs when the mitral valve does not open as wide as it should, restricting the flow of blood out of your left atrium. Measuring how wide your valve can open is important for diagnosing mitral valve stenosis. A normal mitral valve has an area between 4 cm2 and 5 cm2.
Severity of mitral valve stenosis Area of mitral valve
Effect of this area on your health
4.0 cm2 to 5.0 cm2
Normal valve area, no problems apparent Less than 2.0 cm2
Moderate stenosis, symptoms develop when active 1.0 cm2 to 1.5 cm2
Moderately severe, symptoms may develop with mild exertion Less than 1 cm2
Severe stenosis, symptoms present often even while at rest, considered critical Pressure gradient
When the mitral valve becomes narrowed, the left atrium has to contract more strongly in order to force blood across the narrowed valve and into the left ventricle. This more forceful contraction increases the pressure in the left atrium and increases the speed at which blood flows through the narrowed valve. Both left atrial pressure and speed of blood flow across the valve are directly proportional to the degree of mitral stenosis. Thus, small increases in pressure and flow rate are associated with mild mitral valve stenosis and greater increases with more severe mitral valve stenosis. Cardiologists measure left atrial and left ventricular pressure during cardiac catheterization. Flow rates can be measured by echocardiogram.
It can take many years to develop symptoms of mitral valve stenosis (up to 40 years). Your stenosis will probably not need to be treated until you develop symptoms, and even then, it can be successfully treated with medicines for many years. When your mitral valve stenosis becomes more severe, your treatment is likely to change to catheter-based and surgical procedures, with replacement of the mitral valve being the final treatment.
Doctors may also measure the jet velocity of the blood leaving the mitral valve and entering the left ventricle. This is much easier to measure through an echocardiogram than a pressure gradient, and also gives an accurate picture of the severity of mitral valve stenosis. The faster the blood is moving across the mitral valve opening, the greater the pressure in the left atrium must be to achieve that speed, and hence the more severe the stenosis.
| Author: | Robin Parks, MS | Last Updated: March 18, 2008 |
| Medical Review: | E. Gregory Thompson, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology | |
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