Mitral Valve

Q: What is the mitral valve?

A: The mitral valve (also known as the bicuspid valve or left atrioventricular valve) is a dual-flap valve in the heart that lies between the left atrium (LA) and the left ventricle (LV).

Q: How does the mitral valve function?

A: A normally functioning mitral valve opens as a result of increased pressure from the left atrium as it fills with blood. As atrial pressure increases compared to that of the left ventricle, the mitral valve opens. Opening facilitates the passive flow of blood into the left ventricle. This part of the heartbeat, called diastole, ends with atrial contraction, which ejects the final 20% of blood that is transferred from the left atrium to the left ventricle. This amount of blood is known as end diastolic volume (EDV), and the mitral valve closes at the end of atrial contraction to prevent a reversal of blood flow.

Q: Can you describe the anatomic properties of mitral valve?

A: The mitral valve is typically 4-6 cm2 in area. It has two cusps, or leaflets, (the anteromedial leaflet and the posterolateral leaflet) that guard the opening. A fibrous ring known as the mitral valve annulus surrounds the opening. The orientation of the two leaflets resembles a bishop's mitre, from which the valve receives its name.

Q: What is mitral valve stenosis?

A: This is a condition in which the heart's mitral valve is narrowed (stenotic). The abnormal valve doesn't open properly, blocking blood flow coming into your left ventricle, the main pumping chamber of your heart. The upper heart chamber swells as pressure builds up. Blood may flow back into the lungs. Fluid then collects in the lung tissue (pulmonary edema), making it hard to breathe. Mitral valve stenosis can make you tired and short of breath, among other problems.

Q: What is the main cause of mitral valve stenosis?

A: The main cause of mitral valve stenosis is an infection called rheumatic fever, which is related to strep infections. Rheumatic fever – now rare in the United States, but still common in developing countries – can scar the mitral valve. The valve problems develop five to ten years after the rheumatic fever.

Q: Are there any other causes of mitral valve stenosis?

A: Yes, but only rarely do other factors cause mitral stenosis in adults. As you age, excessive calcium deposits can build up around the mitral valve, which sometimes cause significant mitral valve stenosis. Radiation treatment to the chest and some medications also may cause mitral valve stenosis. Children may be born with mitral stenosis (congenital) or other birth defects involving the heart that cause mitral stenosis. Often, there are other heart defects present, along with the mitral stenosis. Mitral stenosis may run in families.

Q: What are the symptoms of mitral valve stenosis?

A: These can include fatigue with increased physical activity, shortness of breath when you lie down, swollen feet or ankles, heart palpitations, frequent respiratory infections, heavy coughing, and rarely, chest discomfort or chest pain.

Q: Will I always have symptoms from the beginning of my disease?

A: No, you can have mitral valve stenosis and feel fine, or you may have only minimal signs and symptoms for decades. However, mild problems can suddenly get worse. These symptoms may appear or worsen anytime you increase your heart rate, such as during exercise. An episode of rapid heartbeats also may accompany these symptoms. Or they may also be triggered by pregnancy or other stress on your body, such as an infection.

Q: What causes the symptoms in mitral valve stenosis?

A: Mitral valve stenosis symptoms usually include the symptoms of heart failure. In mitral valve stenosis, pressure that builds up in the heart is then sent back to the lungs, resulting in fluid buildup (congestion) and shortness of breath.

Q: Are there any signs that my doctor should be aware of if I have mitral stenosis?

A: Yes, mitral valve stenosis may also produce a number of signs that only your doctor will be able to find. These may include: heart murmur, lung congestion, irregular heart rhythms (arrhythmias), pulmonary hypertension, and blood clots.

Q: What are complications of mitral stenosis, if it is left untreated?

A: Mitral valve stenosis can lead to complications such as heart failure, heart enlargement, atrial fibrillations, blood clots, and lung congestion.

Q: What are my treatment options?

A: Treatments to prevent permanent damage to your heart from mitral valve stenosis include medications and invasive procedures. Invasive treatment for mitral valve stenosis is not always needed right away. If tests reveal that you have mild to moderate mitral valve stenosis and you have no symptoms, there's generally no need for immediate valve repair or replacement.

Q: Is there medicine that will cure mild to moderate mitral stenosis?

A: Unfortunately no, medications cannot correct a defect in the mitral valve. However, certain drugs can reduce symptoms by easing your heart's workload and regulating your heart's rhythm.

Q: What kind of medicine will be prescribed to me if I have mild to moderate mitral stenosis?

A: Medications for mild to moderate mitral stenosis may include diuretics, blood thinners (anticoagulants), beta blockers or calcium channel blockers, and anti-arrhythmic medications if you have rhythm disturbances associated with mitral valve stenosis.

Q: What are procedural options for mitral valve stenosis?

A: You may need valve repair or replacement. Both surgical and nonsurgical options are available, and include repair with balloon valvuloplasty (also called valvotomy), or mitral valve repair or valve replacement.

Q: Can you give more detailed information about balloon valvuloplasty?

A: This nonsurgical procedure uses a soft, thin tube (catheter) tipped with a balloon. A doctor guides the catheter through a blood vessel in your arm or groin to your heart and into your narrowed mitral valve. Once in position, a balloon at the tip of the catheter is inflated. The balloon pushes open the mitral valve and stretches the valve opening, improving blood flow. The balloon is then deflated and the catheter with balloon is guided back out of your body. Balloon valvuloplasty can relieve mitral valve stenosis and its symptoms. This procedure may not be appropriate if the valve is both tight (stenotic) and leaky (regurgitant) or if your valve is too heavily calcified. It's also not performed if there's a blood clot in a chamber of your heart, because of the risk of dislodging it. You may need the procedure repeated.

Q: What about mitral valve repair surgery?

A: Mitral valve repair surgery is also called valvuloplasty and is performed using traditional surgical tools. During surgery, a cardiac surgeon may make repairs such as separating fused valve leaflets and removing obstructions on or near the mitral valve. This helps to clear the valve passageway. You may need the procedure repeated if you develop mitral valve stenosis again in the years following surgery.

Q: What is mitral valve replacement surgery?

A: Most people with mitral valve stenosis who need surgery will have mitral valve replacement. Your surgeon will remove the narrowed mitral valve and replace it with a mechanical valve or a tissue valve. The procedure involves all steps of conventional cardiac surgery such as sternotomy and cardiopulmonary bypass.

Q: What is a mechanical valve?

A: Mechanical valves are made completely of mechanical parts, which are non-reactive and tolerated well by the body. The bileaflet valve is used most often. It consists of two pyrolite (qualities similar to a diamond) carbon leaflets in a ring covered with polyester knit fabric.

Q: Do I have to take any anticoagulants (blood thinners) if I get a mechanical valve implanted?

A: All patients with mechanical valve prostheses need to take an anticoagulant medication, such as warfarin (Coumadin), for the rest of their life to reduce the risk of blood clotting and stroke.

Q: What is a biological valve?

A: Biological valves (also called tissue or bioprosthetic valves) are made of tissue, but they may also have some artificial parts to provide additional support and allow the valve to be sewn in place. Biological valves can be made from pig tissue (porcine), cow tissue (bovine), or pericardial tissue from other species.

Q: Do I have to take any anticoagulants if I get a biological valve implanted?

A: No. These valves allow patients to avoid lifetime use of anticoagulants (blood thinning medications).

Q: I have an arrhythmia; if I get mitral valve surgery, will my arrhythmia be cured as well?

A: No, you may continue to be at risk for arrhythmias even after successful surgery for mitral valve stenosis. You may need to take medications to lower that risk or to control your heart rate. A procedure to treat your arrhythmia may be considered in addition to your valve surgery.

Q: What procedures are available to treat abnormal heart rhythms?

A: In some cases your surgeon may perform additional surgery at the time of your operation to try to keep your heart in normal rhythm. One such procedure, called the MAZE procedure, involves making a series of surgical incisions in the upper half of your heart (atria). These heal into carefully placed scars in the atria that form boundaries that force electrical impulses in your heart to travel properly to cause the heart to beat efficiently. Today the MAZE procedure is more commonly performed by radiofrequency ablation or cryoablation, which mimic incisions but leave no extra incisions in the atria.