Mitral Valve Surgery
The mitral valve lies between the upper and lower chambers of the left side of the heart. Once blood returns with oxygen from the lungs, it passes through the left atrium through the mitral valve into the main pumping chamber of the heart, the left ventricle. The valve normally functions as a one-way gate, which opens widely to fill the left ventricle when the heart is relaxed and then closes to prevent any backflow as the heart contracts to eject blood out of the heart through the aortic valve. However, when the mitral valve does not function normally, patients may develop symptoms, such as shortness of breath.
Mitral stenosis means a restriction to the opening of the mitral valve and occurs nearly exclusively as a result of rheumatic fever – usually decades later. Gradually the valve opening becomes more and more limited and it is only when it is moderately to severely narrowed that the patient develops symptoms. Once symptoms become more prominent, the long-term outlook is compromised and an intervention to open the valve should be considered. If the valve remains soft and pliable, it may be possible to open the valve by inflating a balloon within the valve leaflets during a catheterization procedure (“percutaneous mitral balloon valvuloplasty”). However, in many patients, this is not feasible, and the patient may require open-heart surgery either to make incisions in the leaflets to allow them to open better (“mitral commissurotomy”) or to replace the valve.
Mitral regurgitation means the mitral valve is leaking when the heart contracts. There are a number of reasons why this may occur – in some patients, it reflects problems with the valve apparatus and in other patients, it occurs because of heart damage which pulls down on the valve and prevents it from closing properly. In either case, the heart is able to compensate for leakage for a number of years. However, there comes a point when the patient either develops symptoms of shortness of breath and fatigue, or remains asymptomatic despite the heart enlarging severely and developing compromised pumping function, at which point surgery is required.
Most surgeons will try to repair mitral valves rather than replacing them. It is thought that the heart will function somewhat better if it can be repaired, and this may also avoid some of the complications that may occur with valve replacements.
These include infection on a heart valve (endocarditis), clot formation on the valve which can break off and cause a stroke (thromboembolism), risks of bleeding if the patient needs a blood thinner, and the possibility that a tissue valve may wear out.
A variety of different valve types are available, but generally the patient needs to decide with his or her doctor whether a tissue valve or a mechanical valve is preferable. Tissue valves do quite well in older patients, but tend to wear out in younger patients who may require another operation in 10-15 years. Although most surgeons do use a blood thinner, Coumadin, for 3 months after placing tissue valves, this can usually be stopped and the patient will only need to take aspirin to minimize the risk of blood clotting on the valve. Mechanical heart valves require the daily use of a blood thinner, Coumadin, indefinitely. However, it is possible that these patients may never need that valve replaced in the future.
Following an uneventful MV procedure, the patient remains in the hospital for about four to five days and then may be discharged home or to a rehabilitation hospital for a few days of additional care. Patients return for an x-ray, EKG and an office visit, usually two weeks after being discharged. Most patients feel quite well after one to two weeks, but need to limit some activities for about six weeks. It is important that patients become involved in supervised
cardiac rehabilitation. After 6 weeks, most patients are able to go back to work.
Robert M. Bojar, MD