Mitral Valve Disease

Overview

Mitral valve disease refers to any condition that affects the valve between the heart's left upper chamber and its left lower chamber. This valve, called the mitral valve, has two leaflets and opens and closes with each heartbeat to keep blood moving in one direction. When the valve cannot open fully, does not close properly, or has leaflets that move abnormally, the heart must work harder to compensate.

Mitral valve disease is among the most common forms of heart valve disease. Some types progress silently for years or decades without causing any symptoms, while others can follow a faster course. Early diagnosis and regular monitoring play an important role in managing the condition effectively. In more advanced cases, the valve may need to be repaired or replaced.

Types

• Mitral valve prolapse. This is the most common mitral valve condition. One or both leaflets bulge back into the left upper chamber when the left ventricle contracts. In most people it causes no symptoms and requires no treatment beyond monitoring. In some cases, however, the valve leaks blood backward, which may require closer follow-up or intervention.
• Mitral valve regurgitation. The valve does not close completely and blood leaks back into the left upper chamber each time the left ventricle contracts. Because the heart must pump both the forward volume and the leaked volume with every beat, it gradually becomes overloaded and enlarges. Mitral valve prolapse, rheumatic fever, and enlargement of the heart are among the most common causes.
• Mitral valve stenosis. The valve leaflets thicken and fuse together, preventing the valve from opening fully. Less blood passes from the upper to the lower chamber, and pressure builds up in the left upper chamber. Rheumatic fever — which follows untreated streptococcal throat infections — is by far the most common cause worldwide.

Symptoms

The symptoms of mitral valve disease vary depending on the type and severity of the condition. Some people have no symptoms for many years.

• Shortness of breath. This may initially occur only during exertion. As the disease progresses, breathlessness can also develop at rest or when lying flat.
• Fatigue and weakness. When the heart cannot pump efficiently, a persistent sense of exhaustion may develop.
• Palpitations or irregular heartbeat. Mitral valve disease, particularly mitral stenosis and regurgitation, predisposes to an irregular heart rhythm called atrial fibrillation. The heart may feel as though it is racing, fluttering, or beating out of rhythm.
• Swelling in the legs and ankles. Fluid can accumulate in the body, particularly as the disease advances.
• Cough. A persistent cough that worsens when lying flat can be related to increased pressure in the lungs, particularly in mitral stenosis.
• Chest discomfort. Some people may notice a feeling of pressure or tightness in the chest.

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

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

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

Causes

The cause of mitral valve disease varies depending on the specific type.

• Rheumatic fever. Untreated streptococcal throat infections can trigger rheumatic fever, which leaves permanent scarring on the mitral valve leaflets. It is the most common cause of mitral valve disease worldwide, particularly mitral stenosis.
• Mitral valve prolapse. The abnormal motion of the leaflets can gradually lead to blood leaking backward through the valve.
• Heart enlargement and heart failure. As the heart enlarges, the ring supporting the mitral valve stretches and the leaflets may no longer close fully. This is one of the most important causes of mitral regurgitation.
• Heart attack. Damage to the heart muscle can injure the structures that support the mitral valve, causing sudden mitral regurgitation.
• Infective endocarditis. Bacterial infection of the valve leaflets can lead to rapid and serious valve damage.
• Age-related degeneration. Progressive wear of the mitral valve leaflets can lead to regurgitation, particularly in older adults.
• Congenital valve abnormalities. Some people are born with structural differences in the mitral valve.

Diagnosis

Mitral valve disease is often first identified when an abnormal heart sound is heard during a routine examination, or when imaging done for another reason reveals a valve abnormality.

• Echocardiogram (heart ultrasound). The most important test for diagnosing and monitoring mitral valve disease. It shows the structure and motion of the valve leaflets in real time, quantifies the degree of leaking or narrowing, and assesses the size and function of the left upper and lower chambers.
• Electrocardiogram (ECG). Can detect rhythm disturbances, particularly atrial fibrillation, and electrical changes related to chamber enlargement.
• Transesophageal echocardiography. In this technique, an ultrasound probe is passed into the esophagus to obtain much more detailed images of the mitral valve. It is particularly useful before surgical or catheter-based intervention and when infective endocarditis is suspected.
• Cardiac MRI. Can precisely measure the size of the heart's chambers and the volume of blood leaking backward through the valve.

Treatment

Treatment depends on the specific type of mitral valve disease, its severity, and whether symptoms are present.

• Monitoring. In mild to moderate disease without significant symptoms, regular echocardiography and clinical review are sufficient.
• Medications. Drugs cannot repair the valve itself, but they relieve symptoms and help prevent complications. When atrial fibrillation develops, medications to control the heart rate and blood-thinning therapy to reduce the risk of stroke are typically required.
• Valve repair. Repairing the existing valve is preferred over replacing it whenever feasible. Mitral valve repair is particularly successful and produces excellent outcomes in mitral regurgitation. It avoids the need for lifelong anticoagulation, which is a significant advantage.
• Valve replacement. When repair is not possible, the valve is replaced with either a biological or mechanical valve.
• Catheter-based procedures. In suitable patients at higher surgical risk, catheter-delivered devices such as the MitraClip can reduce the backward leak of blood in mitral regurgitation. In mitral stenosis, balloon widening of the narrowed valve is an option in appropriate patients.

Lifestyle and Follow-up

Mitral valve disease requires ongoing monitoring. Echocardiography is performed at regular intervals to assess the valve and the size of the heart's chambers. The frequency of follow-up depends on the severity of the disease.

Keeping blood pressure well controlled slows the progression of valve damage and reduces the workload on the left ventricle. Inform your dentist and every treating doctor about your mitral valve condition. Some patients are advised to take antibiotics before dental procedures and certain surgeries to reduce the risk of valve infection.

Do not wait for a scheduled appointment if new symptoms develop contact your doctor promptly.