Mitral Valve Disease for Stony Brook University Hospital

Basic Facts

• A healthy mitral valve opens wide to allow blood to flow from the left atrium into the left ventricle and closes tightly as blood is pumped out of the left ventricle to prevent any blood from leaking back.
• Mitral valve disease occurs when the mitral valve is unable to open or close properly and includes mitral stenosis, mitral regurgitation, and mitral valve prolapse.
• Mitral valve disease is generally treated with medicine, unless it is severe. Surgical intervention may be either valve repair or replacement.

The heart has four valves, two on the right side of the heart, the tricuspid and pulmonary valves, and two valves on the left side of the heart, the mitral and aortic valves. Each valve is made up of flaplike segments or leaflets that open and close so that blood flows through the heart in only one direction. Located on the left side of the heart, the mitral valve is bicuspid, having two cusps or leaflets.

The mitral valve separates the left atrium and left ventricle. When the heart relaxes the mitral valve opens and blood from the left atrium fills the left ventricle. During the heart's contraction, the mitral valve closes, preventing blood from flowing back to the left atrium. A diseased mitral valve no longer opens or closes properly. Common mitral valve problems are mitral valve prolapse, mitral stenosis, and mitral regurgitation.

Mitral valve prolapse, a common condition, is also called the click-murmur syndrome, floppy valve syndrome, or Reid-Barlow's syndrome. With mitral valve prolapse, one or both of the valve's leaflets may be too large, preventing proper closure and allowing blood to leak back to the atrium. Although infrequently serious or symptomatic, it can be associated with serious mitral regurgitation.

Mitral stenosis is the narrowing or obstruction of the mitral valve, which prevents its opening properly and inhibits blood flow from the atrium to the ventricle. The residual blood can increase the pressure in the atrium, causing it to enlarge, which can lead to atrial arrhythmias, or disturbances in the heart's normal rhythm or rate, and edema, or fluid buildup throughout the body.

Mitral regurgitation (also called mitral valve with insufficiency) occurs when the valve closes incompletely or improperly during the ventricular contraction, allowing blood to flow from the left ventricle back into the atrium. Mild regurgitation may not cause problems, but as regurgitation persists, the left atrium can enlarge because of increased blood volume. Serious regurgitation can cause the left ventricle to compensate for the blood that leaks into the atrium by enlarging. An enlarged heart can grow weak and begin to fail.

WHAT ARE THE SYMPTOMS?

The symptoms of mitral valve disease include:

• Fatigue;
• Shortness of breath;
• Palpitations; and
• Atrial arrhythmias.

As mitral valve disease progresses, the person may develop the symptoms of heart failure, the most notable of which are shortness of breath at rest and resulting from physical exertion.

CAUSES AND RISK FACTORS

Mitral valve prolapse: The causes of mitral valve prolapse are often unknown, but can be caused by Marfan syndrome, a connective tissue disorder.

Mitral Stenosis: The most common cause of mitral stenosis is rheumatic fever, which is an increasingly rare illness in the developed world. The mitral valve is also susceptible to damage from and to the buildup of calcium deposits on and around the valve. Less commonly, mitral stenosis can be congenital, or caused by a malformation that was present at birth.

Mitral regurgitation: Mitral regurgitation may have many causes, including:

• Heart attack;
• Severe ischemia (lack of blood flow to the heart);
• Endocarditis (infection of the heart);
• Hypertension (high blood pressure);
• Traumatic injury;
• Age; and
• Rheumatic fever.

DIAGNOSIS

During a physical exam, a physician may detect heart murmurs, or sounds of abnormal valve function or blood flow through the heart. The physician typically confirms the diagnosis by ordering tests, including:

• X rays;
• Echocardiography (which uses sound waves to produce an image of the heart on a monitor); Electrocardiogram; X ray; Magnetic Resonance Imaging (MRI); and
• Cardiac catheterization and angiography (in which a physician inserts a thin tube called a catheter into an artery in the leg or arm and threads it to the heart). The physician can then measure the pressure inside the heart, the size of the mitral valve opening, and how much blood the heart pumps. The physician can also inject contrast dye through the catheter to produce an angiogram, a specialized x ray of the valves.

TREATMENT APPROACH

People with mild or moderate mitral valve disease, including mitral valve prolapse, may require no treatment for the condition itself. However, people with valve disease must take antibiotics before and after dental procedures, because bacteria from the mouth can enter the bloodstream and cause infection in the heart muscle that can worsen valve disease. Severe cases of mitral valve disease can be treated by surgical procedures, such as:

Balloon valvuloplasty (a balloon-tipped catheter treats mitral stenosis by widening the valve flaps)

Valve repair

The most common kind of repair involves sewing a ring around the entrance to a valve to improve its size or shape.

Valve replacement surgery

Prior to your surgery, you and your physician will discuss the type of valve to use. Your surgeon may use a mechanical valve, made of a carbon-based material and a cloth ring, or a tissue valve, made from a pig heart valve or from a tissue that surrounds a cow's heart sewn to a cloth ring. A mechanical valve is permanent, but clots can develop on them, which means you will have to take blood-thinning medication every day. Tissue valves, on the other hand, may need to be replaced on average in about 15 years, requiring another procedure, but they are less likely to form clots and blood thinners may only be necessary for a few months following the surgery.