Mitral Valve Surgery

Mitral valve operations have been performed since the early days of open-heart surgery during the 1960’s. Occasionally, the mitral valve is abnormal from birth (congenital). More often the mitral valve becomes abnormal with age (degenerative) or as a result of rheumatic fever. In rare instances the mitral valve can be destroyed by infection so called bacterial endocarditis. Mitral regurgitation may also occur as a result of ischemic heart disease (coronary artery disease). When it opens, the mitral valve allows blood to flow into the heart's main pumping chamber called the left ventricle. It then closes (see diagram) to keep blood from leaking back into the lungs when the ventricle contracts (squeezes) to push blood out to the body

Often the mitral valve is so damaged that it must be replaced (refer to Mitral Valve Replacement). More often than not, the valve can be repaired rather than replaced. One type of repair is a procedure called mitral commisurotomy. Mitral commisurotomy can be performed for some valves that are narrow or "stenotic" either from birth or from damage by rheumatic fever. Most often today, rheumatic mitral stenosis is treated by balloon valvuloplasty, a procedure performed in the cardiac catheterization laboratory by interventional cardiologists. Using a catheter with a balloon on the end, the balloon is expanded inside the valve "stretching" it open.

Not all mitral valves can be repaired. A preoperative trans esophageal echocardiogram , may help your surgeon predict the likelihood of repair, but cannot guarantee it. Mitral valves that are diseased due to rheumatic fever are often both stenotic and regurgitant, and are often best treated with replacement. When the pathology is limited to the posterior leaflet, and not heavily calcified, our experience has allowed us to successfully repair 85-90% of such valves.

WHEN IS SURGERY NECESSARY?

The indications for mitral valve repair are undergoing constant re-evaluation. Recent evidence suggests that earlier surgical intervention, particularly if the surgical team has a good record of durable repair, may prevent irreversible damage to the heart. As with all surgery the benefits of the operation must be weighed against the risks of the operation and in the case of valve surgery, the ongoing risk of a prosthetic valve if one needs to be implanted due to a failure of "repair". The decision regarding when to proceed with surgery should be made after close consultation with both your cardiologist and surgeon. This decision will require judgment regarding the risks and benefit of the planned operation. In some cases blood pressure medications, such as ACE-inhibitors can significantly relieve symptoms.

Severe mitral regurgitation in the presence of symptoms of congestive heart failure is most always an indication for surgery. Moderate to severe regurgitation diagnosed by echocardiography, even without overt symptoms may be sufficient to warrant repair, especially if the heart shows signs of enlarging. Enlargement of the left atrium, particularly in the setting of the recent onset of an irregular heartbeat (atrial fibrillation, premature atrial contractions, paroxysmal atrial tachycardia, etc.) is considered by most to be an indication for surgery.

WHAT ARE THE RESULTS OF MITRAL VALVE REPAIR

The first thing to remember is that a surgeon can predict the likelihood of repair before surgery, but cannot guarantee it. If repair is possible, the likelihood of long-term success is good, particularly for degenerative valve disease. Depending upon the underlying abnormality there may be an 85 to 95% chance of needing nothing further done to the valve over the next 10 years or more. If a more complex repair was required for ischemic disease, the chances of long-term freedom from reintervention (further surgery) may be less. If a valve was damaged by rheumatic fever, the disease may progress even after the repair, making the chances of the repair holding up in the long run less likely. Some surgeons are, therefore, reluctant to repair rheumatic valves. The results of repair of mitral regurgitation associated with coronary artery disease are the most difficult of all to predict as the ventricle may continue to "remodel", (enlarge or change shape).

WHAT WILL MY CONDITION BE LIKE AFTER MITRAL VALVE REPAIR?

After a successful mitral valve repair you can expect to return to normal activity within a month of the operation. Following recovery from the operation, you can expect to begin noticing the functional improvement in your breathing and functional capacity after about 6-8 weeks. Anticoagulation (blood thinners) with Coumadin may be prescribed for 6 weeks to 3 months postoperatively, but usually only if there is either preoperative or post op arrhythmias. Generally this prescription is not required in the long term unless other indications for anticoagulation such as atrial fibrillation are present. Once wounds have healed there should be few if any restrictions on a patient's activity.
(For more information about your recovery, refer to What to Expect After Your Heart Surgery.)

You will require prophylactic antibiotics as a preventive measure against infection whenever you have dental work done. We recommend that all patients with valvular heart disease get a dental evaluation and cleaning at least twice a year. Always tell your doctor or dentist that you have had valve surgery before any surgical procedure.

Mitral Valve Replacement: Mechanical vs. Bioprosthetic

When the Mitral valve cannot be repaired then a replacement of the native valve with prosthesis is indicated.

Before undergoing your operation whether it be an Aortic Valve Replacement, or an attempted repair of the Mitral Valve. You and your surgeon will discuss what type of prosthesis is to be used in the event that a repair cannot be done. When your surgeon discusses your upcoming valve operation with you an important option will be presented for your consideration. When the valve cannot be repaired (which is the usual case for degenerative Aortic Valve Disease) a man-made prosthetic valve needs to be implanted. A mechanical valve as its name implies is made of metal usually pyrolytic carbon, a very light but durable metal. As a metal it is generally felt to be indestructible, and should last for your entire life. In rare instances however, even a mechanical prosthesis can malfunction due to scar tissue ingrowth. Since it is metal it is mandatory to thin the blood out so that clots do not form on the valve!! Coumadin a pill that is taken each day will be required to “thin out the blood” so that clots do not form. It is therefore critical that anyone getting a mechanical prosthesis be able to both take coumadin daily and be responsible enough to get his or her blood tested, (eventually once or twice a month) to make sure that the level of anticoagulation is adequate.
(For a more detailed discussion about COUMADIN refer to: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000634)

The other option is a bioprosthesis, the so-called "pig valve". These are as their name implies taken from either a pig’s heart or manufactured from bovine pericardial tissue. Both of these prosthesis, are on the shelf in the operating rooms and come in all sizes. The biologic leaflets are usually held together with a frame of plastic or metal covered by synthetic cloth. This will cause the body to cover it and for that reason NO anticoagulation is required. The disadvantage however is that these biologic valve tend to calcify and can even tear over time. How long they last is up for debate but it is generally felt that the younger you are, the more likely they are to calcify and therefore the quicker you will need a repeat operation to change them out.

The decision to choose a mechanical valve which will last longer, but which requires anticoagulation or a biologic valve is often complicated and not always obvious. A detailed discussion with your physicians regarding your individual life-style, age and habits is critical in making this decision.