Understanding Mitral Repair
Minimally Invasive (Videoscopic) Mitral Valve Repair in progress...
When is a mitral valve repair required?
Functionally a mitral valve allows blood to flow from the left atrium to the left ventricle. When the left ventricle contracts the mitral valve closes and prevents blood from leaking back into the left atrium. A leaking mitral valve or mitral incompetence/regurgitation as it is medically called can develop under several circumstances. In India the most common cause is still Rheumatic Heart Disease.
Other common causes of mitral valve incompetence include following a heart attack or age related degeneration. Less commonly a leaking mitral valve can occur secondary to endocarditis of the valve (infection) or in association with other collagen vascular disorders such as SLE.
The mechanism by which a valve develops a leak often depends on what causes the leak. A common mechanism is when the two leaflets fail to coapt or come together. This can be due to a dilated heart or when the supporting elements of the mitral valve called the chordae elongate, shorten or rupture causing either of the leaflets to prolapse. Once the mitral valve begins to leak it only worsens over time resulting in heart failure. A mitral valve repair is indicated when one becomes symptomatic or severe enough even when there are no symptoms. The diagnosis is usually made on an ECHOCARDIOGRAM. There are well defined guidelines that are followed for example those published by the American Heart Association (AHA).
Mitral Valve Repairs (Last 10 years, STS database)
What happens during a mitral valve repair?
After establishing heart lung bypass the left atrium or the chamber of the heart immediately above the valve is opened. The valve is examined and the cause of the leak established. In most patients a Trans Esophageal ECHO (TEE) would have already determined the exact cause prior to starting the operation. Depending on the mechanism of leak different repair techniques are utilized. If a particular part of the leaflet is found prolapsing it may be resected and remaining leaflet sutured together. In general the philosophy is to preserve. At times the supporting structures such as a chordae may have ruptured to cause a leak. This would require the leaflet to be suspended with artificial chordae made from goretex. Complex repairs often require experience, skill and imagination. Once the repair is complete it is supported by sowing in a ring. A ring is necessary in all repairs if it has to last. Once complete the valve is checked, the heart closed and weaned off bypass. A TEE at the end of the procedure should show little or no leak if the repair is successful. Rarely it may be necessary to go back and rerepair when a leak persists on the TEE. It should be remembered that there is always a small chance <1% of replacing the valve after a planned repair. The more experienced one is in repair the likelihood of replacement becomes less likely.