Mitral stenosis is an abnormal narrowing of the mitral valve, which is one of the heart valves. This "tight" valve obstructs the flow of blood within the heart.
What is going on in the body?
The human heart has 4 chambers. In the normal heart, the mitral valve helps control blood flow between 2 of these chambers, the left atrium and the left ventricle. In mitral stenosis, the valve does not open enough to allow proper blood flow into the left ventricle, the heart's primary pumping chamber. This abnormal blood flow can cause changes and damage to the heart and lungs.
What are the causes and risks of the condition?
Most cases of mitral stenosis are due to the long-term consequences of rheumatic fever. Rheumatic fever can occur after group A streptococcal infections of the throat that are not treated with antibiotics. If this infection is not treated adequately with antibiotics, mitral stenosis may occur years later.
Rare causes of mitral stenosis include:
- congenital heart disease, (valve defects present at birth)
- inflammation of the mitral valve from various illnesses
The risks of mitral stenosis are related to the "tightness" of the valve. A person with mitral stenosis may live a lifetime with no problems. However, a person with severe mitral stenosis is at increased risk of permanent heart damage. Arrhythmias, (irregular heartbeats) can occur and lead to blood clots.
What can be done to prevent the condition?
In children with certain throat infections, proper antibiotic treatment can prevent this condition. Other causes are not usually preventable.
How is the condition diagnosed?
A healthcare provider to suspect this condition from the patient's history if symptoms followed an episode of strep infection. A heart murmur can often be heard with a stethoscope. A heart tracing, or ECG, and chest x-ray may show certain abnormalities. Special x-ray tests, such as a cardiac catheterization, can determine the severity of the condition and help guide treatment.
Long Term Effects
What are the long-term effects of the condition?
Long-term effects depend on the tightness of the valve. A person with mild mitral stenosis may have no long-term effects. A person with severe mitral stenosis may have serious heart and lung complications, including irregular heartbeats, blood clots, and permanent heart damage.
What are the risks to others?
Mitral stenosis is not contagious and poses no risk to others. However, the infection that causes rheumatic fever, the most common cause of mitral stenosis, is contagious.
What are the treatments for the condition?
A person with no symptoms or heart problems may be advised to take antibiotics before surgery or dental work. In general, treatment depends on the severity of the condition and which problems have occurred. Heart medications may be used to slow the heart or treat irregular heartbeats. Medications used to prevent blood clots may be used in a person with arrhythmias.
A person who continues to have symptoms despite medical therapy may have heart valve surgery to fix the valve or replace it with an artificial one. In some cases, the valve can be opened in a cardiac catheterization laboratory. The cardiologist uses a special type of balloon to force open the narrowed leaflets of the mitral valve and thereby avoid open heart surgery.
What are the side effects of the treatments?
A person treated with medication may have side effects related to the medications used. All surgery carries a risk of bleeding, infection, and reactions to the anesthesia medication. Valve repair may need to be repeated or in time may require valve replacement. A person with an artificial valve may require medication to prevent blood clots, for life in some cases. A biomechanical (tissue) heart valve is subject to wear and tear and may need replacement after years of use. A mechanical heart valve can last indefinitely, but requires a person to take a blood thinning medication for the rest of his or her life.
What happens after treatment for the condition?
In many cases, treatment does not end. The person usually returns to normal activity after recovery from surgery. Medications to prevent blood clots and treat abnormal heartbeats may be needed. A person with a biomechanical valve, or who has had his or her natural valve opened in the catheterization lab, may need to take a blood thinner for only a few months.
How is the condition monitored?
Regular visits to the healthcare provider are often advised. Repeat testing, such as an ultrasound of the heart known as an echocardiogram, may be done to make sure the valve is stable. Medications for abnormal heartbeats and blood clots need to be monitored as well.
Merck Manual, 1999
Current Medical Diagnosis and Treatment, 1996
Harrison's Principals in Internal Medicine, 1991