Blood Flow Through the Heart The heart is composed of four chambers. The two upper chambers are the atria and the two lower chambers are the ventricles. After blood has traveled through the body, it returns to the upper right atrium. When the heart beats, blood from the right atrium is forced through a one-way valve, the tricuspid valve, into the right ventricle. Then, the blood flows through the pulmonary valve into the lungs. Here, carbon dioxide is released and oxygen is absorbed. Next in the circuit, the blood travels into the left atrium, then on through the mitral valve into the left ventricle. Finally, blood is forced through the aortic valve, into the aorta (the main blood vessel leaving the heart) and then on to the body.

Mitral Valve Stenosis The mitral valve contains two triangular flaps, called leaflets. As the heart beats, the leaflets open, allowing blood inside the left atrium to flow into the left ventricle. The leaflets then close to prevent blood from flowing backward.

Mitral valve stenosis is a condition in which the valve leaflets don't open fully, impeding blood flow in the left side of the heart. Blood can't adequately leave the left atrium, leading to increased pressure within that chamber. The left atrium may enlarge and blood may back up into the lungs, causing pulmonary congestion and pulmonary hypertension. Symptoms of mitral valve stenosis usually develop between 20 and 50. Patients may develop shortness of breath, fatigue, frequent bouts of respiratory infection, heart rhythm problems (atrial fibrillation), cough, dizziness, chest pain and blood clots.

The most common cause of mitral valve stenosis is rheumatic fever, an inflammatory condition that sometimes develops after strep throat. Rheumatic fever may cause the leaflets of the mitral valve to thicken, interfering with the opening of the valve. Sometimes babies are born with a narrowed mitral valve. In rare cases, tumors or blood clots may block the valve and interfere with the passage of blood.

Treating Mitral Valve Stenosis Patients with mild symptoms may not need treatment for mitral valve stenosis. However, they will need to take antibiotics before any invasive medical or dental procedure to reduce the risk of infection in the heart valve.

Those with moderate to severe stenosis may need a valve replacement or repair. In mitral valve replacement, the diseased valve is removed and replaced with a mechanical or donor valve (from a human cadaver, cow or pig). Patients who have a mechanical valve replacement must take anti-coagulant medications for the rest of their lives to reduce the risk of developing dangerous blood clots.

A mitral valve may also be surgically repaired by shaving or cutting away calcium deposits that prevent the leaflets from fully opening. The procedure is often performed through a small incision made into the chest.

Balloon Repair Doctors with Sentara Healthcare in Norfolk, VA, are using another approach to mitral valve repair. First, a balloon-tipped catheter is inserted through an artery in the leg, then fed through the circulatory system to the right side of the heart. Next, a tiny hole is made through the wall that divides the heart, providing access to the mitral valve on the left side. The tip of the catheter is placed inside the valve and the balloon is inflated. As the balloon expands, it pushes open the leaflets, enabling them to open more fully. The balloon is then deflated and the catheter is withdrawn.

Recovery with the balloon procedure is much faster than surgical repair or replacement. Patients gain relief quickly and may be back to regular activities within a few days.

For information on mitral valve disease: American Heart Association, http://www.americanheart.org, or contact your local chapter The Society of Thoracic Surgeons, http://www.sts.org