Mitral Valve Stenosis
A narrowed mitral valve that restricts blood flow in the heart
Quick Facts
- Type: Heart valve disease
- Valve affected: Mitral valve
- Common cause: Past rheumatic fever
- Key symptoms: Shortness of breath, fatigue, palpitations
Overview
Mitral valve stenosis is a condition in which the mitral valve, the valve between the upper and lower chambers on the left side of the heart, becomes narrowed and stiff. This narrowing restricts blood flow from the left atrium into the left ventricle, causing blood and pressure to back up into the lungs.
The most common cause worldwide is rheumatic fever, an illness that can follow an untreated strep throat infection and damage heart valves years later. As the valve narrows over time, the heart works harder and pressure builds in the lungs, leading to symptoms such as breathlessness and fatigue. With diagnosis and treatment, symptoms can be managed and the valve repaired or replaced when needed.
Symptoms
Mitral stenosis often develops slowly, and some people have no symptoms for years. As it progresses, symptoms may include:
- Shortness of breath, especially with exertion or when lying down
- Fatigue and reduced ability to exercise
- Heart palpitations or an irregular heartbeat
- Swelling in the legs or feet
- Coughing, sometimes with blood-tinged sputum
- Chest discomfort
- Frequent respiratory infections
Symptoms can worsen with anything that makes the heart work harder, such as exercise, pregnancy, or infection. Seek emergency care for sudden severe shortness of breath, fainting, or chest pain.
Causes
Mitral stenosis develops when the valve leaflets thicken, stiffen, or fuse, narrowing the opening. Causes include:
- Rheumatic fever: The leading cause worldwide, resulting from an immune reaction after untreated strep throat that damages the valve over time.
- Calcium buildup: Age-related calcification of the valve, more common in older adults.
- Congenital narrowing: A valve that is abnormally narrow from birth, which is rare.
- Other causes: Certain conditions that affect the valve, including some autoimmune diseases and prior radiation to the chest.
Risk Factors
- A history of rheumatic fever or untreated strep throat
- Older age, for calcium-related narrowing
- Certain congenital heart conditions
- Living in regions where rheumatic fever is more common
Diagnosis
A clinician may first suspect mitral stenosis after hearing a characteristic heart murmur. Tests confirm the diagnosis and assess severity.
- Echocardiogram: An ultrasound of the heart that shows the valve, measures the narrowing, and assesses blood flow. This is the main test.
- Electrocardiogram (ECG): Detects abnormal heart rhythms such as atrial fibrillation.
- Chest X-ray: May show an enlarged heart chamber or changes in the lungs.
- Cardiac catheterization: Sometimes used to measure pressures and plan treatment.
Treatment
Treatment depends on symptoms and how narrow the valve is. Mild cases may need only monitoring, while significant stenosis often needs a procedure.
- Medications: Drugs to control heart rate and rhythm, reduce fluid buildup, and, when atrial fibrillation is present, blood thinners to lower stroke risk. Medications relieve symptoms but do not fix the narrowing.
- Balloon valvuloplasty: A catheter-based procedure that widens the valve with a balloon, suitable for many people.
- Valve repair or replacement: Surgery to repair or replace the valve when the narrowing is severe or not suitable for balloon treatment.
Regular follow-up helps track the valve and guide the timing of any procedure.
Prevention
Because most cases stem from rheumatic fever, prevention focuses on preventing and treating strep infections:
- Seek treatment for strep throat so it can be treated with antibiotics
- Complete the full course of prescribed antibiotics for strep infections
- Follow medical advice on long-term antibiotics if you have had rheumatic fever, to prevent recurrence
- Attend regular heart check-ups if you have known valve disease
When to See a Doctor
See a clinician if you have unexplained shortness of breath, fatigue, palpitations, or leg swelling, especially if you have a history of rheumatic fever. Early evaluation allows monitoring and timely treatment. Seek emergency care for sudden severe breathlessness, fainting, chest pain, or coughing up blood, which need immediate attention.
Frequently Asked Questions
What causes mitral valve stenosis?
The most common cause worldwide is rheumatic fever, which can follow an untreated strep throat and damage the valve over the years. In older adults, calcium buildup on the valve can also cause narrowing, and rarely the valve is narrow from birth.
What are the main symptoms of mitral stenosis?
Common symptoms include shortness of breath, especially with activity or when lying down, fatigue, palpitations or an irregular heartbeat, and leg swelling. Some people have no symptoms for years before the valve narrows enough to cause problems.
How is mitral valve stenosis treated?
Medications can control heart rate and rhythm and reduce fluid, but they do not fix the valve. Significant narrowing is treated with a balloon procedure to widen the valve, or with surgery to repair or replace it, depending on the situation.
Can mitral valve stenosis be prevented?
Many cases can be prevented by treating strep throat promptly to avoid rheumatic fever, and by taking long-term preventive antibiotics if recommended after rheumatic fever. Preventing the original infection is the key step.
Why does mitral stenosis cause an irregular heartbeat?
The increased pressure stretches the left atrium, which can disturb the heart's electrical signals and lead to atrial fibrillation. This irregular rhythm raises the risk of blood clots and stroke, so blood thinners are often prescribed when it occurs.
References
- American Heart Association. Problem: Mitral Valve Stenosis.
- MedlinePlus, U.S. National Library of Medicine. Mitral stenosis.
- Mayo Clinic. Mitral valve stenosis — Symptoms and causes.
- National Heart, Lung, and Blood Institute (NHLBI). Heart Valve Diseases.