Mitral Valve Repair and Replacement Surgery
Mitral Valve Replacement
For many years, valve replacement with artificial or biological prosthetics was the standard of care. While today, a well performed mitral valve repair is viewed as superior, particularly for valve regurgitation, replacement is still a viable option for some patients. Artificial valves are extremely durable, but they do require patients to take anticoagulant (anti-clotting) medication every day to prevent stroke. These medications, while effective, may cause side effects and require monitoring. Biological valve replacements (made from animal tissue or from human donors) are better tolerated, but are not as durable as artificial valves. They frequently last 10-15 years, necessitating repeat operations.
Mitral Valve Repair
Many types of diseases are amenable to mitral valve repair. Mitral valve repair is the preferred approach when it can be done with a satisfactory early result and expectation of good durability of repair. There has been a shift in the types of mitral valve disease in the western world, now most patients present with mitral valve insufficiency from mitral valve prolapse or other degenerative processes, and away from the post inflammatory valve destruction of rheumatic heart disease. As a result the majority of mitral valve disorders can be repaired by modern surgical techniques in experienced hands.
Modern mitral valve repair consists of surgically remodeling or reconstructing the valve to eliminate any leakage or blockage. Torn parts of the leaflet and its support structures are often resected and other leaflet tissues moved surgically to recoup the loss and restore competency. Other times leaky leaflet tissues are resupported by the use of artificial materials such as Gortex. Finally, the majority of the valve repairs are supplemented by the addition of a ring placed around the base of the valve insertion in the heart to add temporal stability to the reconstruction. While the techniques can differ, the principles of restoring adequate leaflet coaptation in the annular plane, and thus competency of the valve, remain the same.
Advantages of Mitral Valve Repair Over Replacement
There are many advantages of mitral valve repair over replacement. These include a 2 to 3 fold reduction in operative mortality. There is a lower complication rate and some centers report less transfusions. Patients whose valves have been repaired have a better survival over the next 10 to 20 years compared to patients who received a prosthetic valve. The durability of the repair exceeds that of tissue prosthesis and the reoperation rate is much lower. There is a lower incidence of stroke, and less requirements for anticoagulation, only for patients in atrial fibrillation. Valve repairs preserve the geometry and function of the left ventricle. In patients who undergo valve repair prior to deterioration of left ventricular function the survival is similar to patients without mitral valve disease. Finally, repaired mitral valves have better resistance to infections compared to prosthetic valves.
Because the results of valve repair done by experienced surgeons in experienced centers are so good and so advantageous over replacement, repair has become the standard of care for degenerative mitral valve disease. In the United States approximately 50% of these valves are repaired, but at experienced centers this easily increases to over 90-95%.
Severe Mitral Regurgitation
All patients with severe mitral regurgitation should be evaluated for surgery. Most patients without other severe medical conditions or other limitations of life expectancy, will be appropriate candidates for mitral valve procedures. For patients who have no symptoms and in whom there has been no change in heart function, surgery is recommended if the diagnostic echocardiogram indicates a high expectation that the valve is indeed repairable. Otherwise, all patients with severe mitral regurgitation and symptoms of shortness of breath, or exercise intolerance should undergo mitral valve surgery and preferably repair. Similarly, all patients with severe mitral regurgitation and worsening heart function should have there heart valve addressed immediately. Advanced age does not preclude safe valve surgery as long as the patient is not otherwise frail.
Functional Mitral Regurgitation
One other category of mitral valve disease is called functional mitral regurgitation which is mitral valve insufficiency from an injured or failing heart. These cardiac conditions are referred to as cardiomyopathy and ischemic cardiomyopathy. Specific to these diseases, the mitral valve is normal, but the leaflet edges do not meet creating a large leak, because its supporting structures are pulled away and outward by the dilatation of the heart. These valves can be and should be repaired. In this case the ring placed around the base of the valve insertion in the heart is undersized and overly narrowed to achieve adequate coaptation of the leaflets. For the majority of patients with functional MR a valve repair is associated with better operative and long term results. Unlike valve repair for primary valve disorders the risks of surgery are greater and the long term results not as encouraging.