Mitral Valve Stenosis

Overview

Mitral valve stenosis is a condition in which the mitral valve, located between the heart's left upper and left lower chambers, cannot open fully. When the left upper chamber contracts, a healthy mitral valve opens completely to allow blood to flow freely into the left lower chamber. In mitral stenosis, the valve leaflets have become thickened, stiffened, or fused together and the opening is narrowed. Less blood passes through to the left lower chamber, and pressure begins to build up in the left upper chamber.

This pressure is eventually transmitted back to the blood vessels supplying the lungs, the left upper chamber gradually enlarges, and conditions develop for fluid to accumulate in the lungs. Because the disease generally progresses slowly, symptoms most often appear over years and can be subtle in the early stages.

Rheumatic fever, which follows untreated streptococcal throat infections, is the most common cause of mitral stenosis worldwide. While rheumatic heart disease is declining in developed countries, it remains a significant problem in many parts of the world. With early diagnosis and appropriate treatment, the course of the disease can be meaningfully improved.

Symptoms

Mitral valve stenosis may produce no symptoms for many years. Symptoms tend to emerge when the valve opening narrows below a critical level, or when situations arise that cause the heart to beat faster. Pregnancy, infection, physical exertion, or the onset of atrial fibrillation can all raise the heart rate and bring previously silent mitral stenosis to the surface quite suddenly.

• Shortness of breath. This is one of the most common symptoms. As pressure builds in the left upper chamber and backs up into the lung vessels, breathing becomes more difficult. It may initially occur only during exertion. As the disease progresses, breathlessness can develop at rest or when lying flat.
• Fatigue and weakness. When less blood passes through to the left lower chamber, the body receives less than it needs and a persistent sense of exhaustion may develop.
• Palpitations or irregular heartbeat. As the left upper chamber enlarges, an irregular rhythm called atrial fibrillation can develop. In mitral stenosis, atrial fibrillation can abruptly worsen symptoms and substantially raises the risk of stroke.
• Cough. Increased pressure in the lung vessels can cause a dry or occasionally blood-tinged cough, particularly when lying flat.
• Swelling in the legs and ankles. As the disease advances and the right side of the heart is also affected, fluid can accumulate in the body.
• Chest discomfort. Some people may notice a feeling of pressure or tightness in the chest.
• Hoarseness. In rare cases, the enlarged left upper chamber can press on a nearby nerve that controls the voice, causing hoarseness.

When to Seek Medical Care

See a doctor if you notice any of the following.

• Shortness of breath during activity or at rest
• Palpitations or a sensation of irregular heartbeat
• Unexplained fatigue and a decline in exercise capacity
• Swelling in the legs or ankles
• A cough that worsens when lying flat

Call emergency services immediately if you experience any of the following.

• Sudden, severe shortness of breath
• Coughing up blood
• Fainting or nearly fainting
• Sudden, severe chest pain
• A very rapid or markedly irregular heartbeat

Causes

Rheumatic fever is by far the most common cause of mitral stenosis. Other causes can also produce this condition.

• Rheumatic fever. When a streptococcal throat infection caused by Group A streptococcus bacteria goes untreated, the immune system can mistakenly attack heart valve tissue. This process causes the mitral valve leaflets to thicken, scar, and fuse at their edges. The cardiac effects of rheumatic fever typically appear ten to twenty years after the initial episode. Repeated attacks of rheumatic fever cause progressively more severe valve damage.
• Age-related calcification. In older adults, calcium deposits can develop in the mitral valve ring and leaflets, restricting their movement and causing mild to moderate narrowing. This follows a different mechanism from rheumatic stenosis and generally progresses more slowly.
• Congenital mitral stenosis. Very rare. Some infants are born with a mitral valve that is structurally narrowed from birth.
• Radiation damage. Radiotherapy delivered to the chest can affect the mitral valve over time and contribute to stenosis.

Risk Factors

• A history of rheumatic fever. This is the most important risk factor. Untreated or recurrent rheumatic fever significantly raises the risk of mitral valve damage.
• Recurrent streptococcal throat infections. Frequent streptococcal infections that are not adequately treated increase the risk of rheumatic fever and subsequent valve damage.
• Older age. Calcification-related narrowing becomes more common with advancing age.
• A history of chest radiotherapy. People who have received radiation to the chest, particularly for lymphoma or breast cancer, face an increased long-term risk of valve damage.

Diagnosis

The diagnosis of mitral stenosis is established through clinical assessment and imaging. Accurately determining the degree of narrowing and its effects on the left upper chamber and the lung vessels shapes both the monitoring plan and the timing of intervention.

• Medical history and physical examination. The onset and progression of symptoms are discussed. A history of rheumatic fever or frequent streptococcal throat infections is specifically important. When the doctor listens to the heart, a murmur heard during diastole, the phase when the heart relaxes and the mitral valve should be open, is the hallmark of mitral stenosis. A characteristic opening snap may also be heard, reflecting the stiffened leaflets snapping open under pressure.
• Echocardiogram (heart ultrasound). The most important test for diagnosing and monitoring mitral stenosis. It shows the thickness and movement of the valve leaflets and whether they have fused together. It measures the mitral valve opening area. In a normal valve this area is four to six square centimeters; in severe stenosis it can fall below one and a half square centimeters. It assesses the size of the left upper chamber and the pressure in the lung vessels. Doppler imaging measures the speed of blood flow across the valve, which allows the severity of the narrowing to be calculated precisely.
• Transesophageal echocardiography. In this technique, an ultrasound probe is passed into the esophagus to provide much more detailed images of the mitral valve than standard ultrasound can achieve. It is essential before balloon widening of the valve to confirm that no clot is present in the left upper chamber. If a clot is found, the balloon procedure cannot safely be performed.
• Electrocardiogram (ECG). Used to detect the electrical changes associated with left upper chamber enlargement and to identify atrial fibrillation.
• Chest X-ray. Can show enlargement of the left upper chamber and fluid accumulation in the lung vessels. Calcification of the valve may occasionally be visible on this image.
• Cardiac MRI. Precisely measures the size and function of the heart chambers. It may be used when standard imaging is insufficient or when additional information about associated valve conditions is needed.
• Exercise stress test. May be used in apparently asymptomatic patients to objectively measure exercise capacity and assess the rise in lung vessel pressure with exertion. This information can influence the timing of intervention.
• Coronary angiography or coronary CT angiography. Before valve surgery, the coronary arteries are assessed, particularly in patients over 50 or those with cardiovascular risk factors.

Treatment

Treatment of mitral stenosis depends on the degree of narrowing, the presence of symptoms, and the effect on the lung vessels. In mild stenosis, monitoring is sufficient. In moderate to severe stenosis, intervention is required.

Monitoring

In mild and asymptomatic mitral stenosis, regular echocardiography is used to track the valve area and the size of the left upper chamber over time. Any new symptoms or the development of atrial fibrillation should prompt immediate medical attention.

Medications

Medications cannot correct the valve narrowing itself but relieve symptoms and help prevent complications.

• Diuretics. These remove excess fluid from the lungs and body, relieving breathlessness and swelling. They provide the most rapid symptomatic relief of any medication used in this condition.
• Heart rate-controlling medications. In mitral stenosis, a faster heart rate leaves less time for blood to pass through the narrowed valve and worsens symptoms substantially. Beta-blockers and calcium channel blockers slow the heart rate, allowing more time for blood to flow through, which can meaningfully relieve symptoms.
• Blood thinners. When atrial fibrillation develops or a clot is found in the left upper chamber, anticoagulation is essential to reduce the risk of stroke. In rheumatic mitral stenosis, anticoagulation may also be recommended in some patients without atrial fibrillation if other stroke risk factors are present.
• Long-term antibiotics to prevent rheumatic fever recurrence. In people with rheumatic heart disease, long-term preventive penicillin therapy is used to prevent recurrent streptococcal infections and further valve damage. This is particularly important in younger patients and in those who have not yet undergone valve intervention.

Balloon Mitral Valvuloplasty

In suitable patients, this catheter-based procedure is both highly effective and the preferred first interventional treatment. It does not require open heart surgery.

A thin catheter is passed through a blood vessel in the groin and guided to the heart. It is directed through the wall separating the upper chambers to reach the mitral valve. A small balloon at the tip of the catheter is then inflated at the point where the leaflets have fused, pushing them apart and widening the valve opening. Once the balloon is deflated and the catheter removed, the procedure is complete. Recovery is much faster than after open heart surgery, and the hospital stay is typically one to two days.

Balloon valvuloplasty is not suitable for every patient. Heavy calcification of the leaflets, significant backward leaking of blood through the valve, or the presence of a clot in the left upper chamber may prevent the procedure from being performed safely. Transesophageal echocardiography must confirm that no clot is present in the left upper chamber before the procedure can go ahead.

Surgical Treatment

Surgical options are considered when balloon valvuloplasty is not suitable or has already been performed previously.

• Mitral commissurotomy. An open heart operation in which the fused leaflet edges are separated. When the leaflets are still in reasonable condition, this approach can restore the valve's function while preserving the patient's own tissue, which means anticoagulation is not needed afterward.
• Mitral valve replacement. When the leaflets are too severely damaged or when significant backward leaking is also present, replacement becomes necessary. The choice between a biological and a mechanical valve is made in discussion with the cardiologist and surgeon based on the patient's age, circumstances, and preferences.

Complications

Untreated or inadequately monitored mitral stenosis can lead to serious complications over time.

• Atrial fibrillation. The most common complication. The enlarging left upper chamber is prone to developing atrial fibrillation, which can abruptly worsen symptoms and substantially raises the risk of stroke.
• Stroke and blood clots. Blood moves more slowly through the enlarged left upper chamber and clots can form. If a clot travels to the brain, stroke can result. This risk is considerably higher when atrial fibrillation is also present.
• Pulmonary hypertension. Sustained elevated pressure in the left upper chamber is transmitted back to the lung vessels, eventually causing permanently elevated pressure in those vessels. This worsens symptoms and increases the risk associated with any intervention.
• Right heart failure. The increased pressure in the lung vessels places a sustained demand on the right side of the heart. Over time this can cause the right ventricle to weaken, leading to leg swelling, abdominal fluid accumulation, and severe fatigue.
• Heart failure. As the disease advances, the heart may eventually lose its ability to pump sufficient blood to meet the body's needs.

Lifestyle

Living with mitral stenosis requires long-term attention and monitoring. The right measures can relieve symptoms and reduce the risk of complications.

Physical Activity

In mild stenosis, many people can maintain a near-normal level of physical activity. In moderate to severe stenosis, exercise raises the heart rate, which reduces the time available for blood to pass through the narrowed valve and can noticeably worsen symptoms. Your cardiologist should guide you on what type and intensity of activity is safe. Activities that cause the heart rate to rise rapidly are generally best avoided.

Salt and Fluid Intake

In patients with breathlessness or swelling, reducing daily salt intake helps prevent fluid accumulation. Ask your doctor for a specific daily salt target that suits your situation.

Vigilance About Fever and Throat Infections

In people with rheumatic mitral stenosis, recurrent streptococcal throat infections can cause further valve damage. Seek medical attention promptly if fever or throat pain develops. Take the preventive antibiotic therapy prescribed by your doctor consistently and do not miss doses.

Medications

Taking all prescribed medications consistently is essential. Patients on blood thinners must not miss doses and should maintain scheduled INR monitoring. Do not stop any medication without medical guidance. Always inform any other treating doctor about your valve condition and current medications before a new drug is started.

Planning a Pregnancy

Mitral stenosis is one of the most important valve conditions affecting pregnancy. During pregnancy, blood volume increases and the heart works harder and faster. These changes can significantly worsen symptoms, particularly in moderate to severe mitral stenosis. If you are planning a pregnancy, discuss this thoroughly with your cardiologist before conception. Some medications may need to be changed, and close cardiac monitoring throughout pregnancy is essential.

Regular Follow-up

Mitral stenosis requires regular monitoring. Echocardiography is used at defined intervals to measure the valve area, the size of the left upper chamber, and the pressure in the lung vessels. Monitoring for atrial fibrillation is an ongoing part of follow-up. Contact your doctor or seek emergency care if any of the following develop.

• Shortness of breath that returns or worsens
• Palpitations or a sensation of irregular heartbeat
• Swelling in the legs or ankles
• Fainting or nearly fainting
• Coughing up blood

Preparing for Your Appointment

Coming prepared to an appointment for mitral valve stenosis helps your doctor make a more accurate assessment and choose the most appropriate treatment for you.

What You Can Do

• Write down when symptoms began and how they have progressed.
• Share any history of rheumatic fever or frequent streptococcal throat infections.
• Bring any previous echocardiography reports if you have them.
• List all medications and supplements you are currently taking.
• Mention any pregnancy plans.
• Write your questions down before the appointment.

Questions You May Wish to Ask Your Doctor

• How severe is my valve narrowing?
• Is balloon valvuloplasty a suitable option for me?
• Is surgery needed and if so, when?
• Do I need long-term antibiotics to prevent rheumatic fever from recurring?
• What type and intensity of exercise is safe for me?
• I am planning a pregnancy what risks does this condition create?
• How often do I need follow-up appointments?

Questions Your Doctor May Ask You

• When did symptoms begin and how have they progressed?
• Have you had rheumatic fever or frequent throat infections in the past?
• Does breathlessness occur during exercise or also at rest?
• Are you experiencing palpitations or a sensation of irregular heartbeat?
• What medications are you currently taking?
• Have you received radiation to the chest?
• Are you planning a pregnancy?