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Mitral Valve Disease
Mitral regurgitation or leakage is the major issue seen with this valve in the United States today. The causes can be related to muscle ischemia or heart attack combined with dilation of the left ventricle (pumping chamber). These conditions pull the valve apart and cause leakage. Some heart attacks cause the muscle attachments of the valve to rupture and cause severe leakage of 10 times requiring emergent repair or replacement of the valve. Up to 20% of patients undergoing coronary artery bypass have some degree of mitral valve insufficiency. It will be up to the judgment of your surgeon whether the valve will get better with more blood supply or require specific valve repair.
The second common cause of mitral leakage is myxomatous degeneration. This involves weakness of the chordae tendinae (attachment of valve leaflet to muscle). These chordae can rupture or tear and cause the valve leaflets to flap up and cause leakage. This can occur gradually over time or several can rupture at the same time causing the patient to become very short of breath.
The third cause of leakage is endocarditis or infection of the valve. The infection most commonly destroys the leaflet and or deposits vegetations (collections of infected material on the valve). The infection can also affect the annulus (ring where leaflets attach) and can further destroy the heart wall or chordae tendinae attachments.
Rheumatic diseases was a prominent part of valve disease in the United States. Due to better and faster treatments of streptococci throat infections, this disease has almost been eliminated in the states. Many areas of the world still have pockets of rheumatic disease. The inflammatory process and subsequent scarring can result in mitral stenosis (narrowing), mitral regurgitation or most commonly combined stenosis and regurgitation.
The symptoms of regurgitation (leaking valves) are primarily shortness of breath. This can occur abruptly and be severe as with multiple chord rupture or papillary muscle ruptures. These situations may necessitate emergent life saving surgery.
Patients with chronic regurgitation may not have obvious symptoms. These patients gradually slow down and may only be very short of breath with extreme activity. As the ventricle begins to fail or the patient goes into atrial fibrillation (irregular heartbeat) the patient becomes more short of breath.
Patients with mitral stenosis primarily have shortness of breath. Again this may not be too evident clinically in the beginning. But as the stenosis progresses, the pulmonary pressure rise, atrial fibrillation occurs, and the patient goes into heart failure. It then becomes necessary to surgically intervene.
Mitral stenosis is generally treated by removing the diseased valve and replacing it either with a mechanical (metal valve) or broprosthesis (animal tissue valve). It is also likely the patient has atrial fibrillation. These patients need a surgical ablation of the atrial fibrillation. The patient will also have a coronary angiogram and bypasses will be done as necessary.
Mitral insufficiency is preferably treated as a repair. Based the results of diagnostic testing, the surgeon will advise as to the possibility of repair before surgery, but final decision is based on the quality and strength of remaining valve tissue.
The basic aspects of repair are to rebuild chordue with gortex string, remove damaged portions of leaflets, and place a ring around the valve to bring the leaflets into better alignment. Think of the ring like a belt holding up a pair of pants that are too big. If the valve is judged not to be good for repair, it will be replaced. Repairs if possible are preferred because they preserve the quality of ventricle function. Likelihood of repair depends also on the operative experience of your surgeon. Our philosophy is repair first if reasonably possible.