April 7, 2010

A Clip For Leaking Mitral Valves

A clothespin-like clip, inserted through a vein in the groin, is a promising alternative to open-heart surgery.

A new approach to repairing the heart's mitral valve can be used on patients who are too weak to undergo conventional surgery and also leads to fewer short-term complications than conventional surgery does.

The new procedure involves threading a clothespin-like clip, called a MitraClip, through a vein in the groin all the way to the heart, where it's attached to the mitral valve much like stitches would be. The clip permits the valve to close properly during heartbeats. As uncomfortable as this procedure may sound, it's much less stress on the body than conventional open heart surgery is.

When the valve doesn't close properly, it leads to an overworked heart and poor tissue oxygenation.

Patients receiving the clip can be up and around one week later, compared to six weeks for conventional surgery patients.

Normally, the mitral valve acts like a swinging door. It opens after the heart beats, allowing freshly oxygenated blood to enter the heart's left ventricle, replacing the blood that's just been pumped to the body's tissues. The valve then closes when the heart beats again, so the oxygenated blood doesn't flow backwards.

When the valve doesn't close properly, it leads to an overworked heart and poor tissue oxygenation. Defects in the mitral valve can be relatively minor or they can be serious enough that a person is virtually confined to bed.

To imagine what it's like to have a leaky mitral valve, stand inside a store near its outer door during winter. When the door opens, cold air comes into the store. This stops when the door closes. If the door doesn't close properly, cold air will constantly leak into the store and you'll be freezing.

About four million Americans have some degree of mitral valve leakage and another 250,000 cases are diagnosed each year. Current surgical treatment requires surgeons to open the chest and stitch the two parts of the mitral valve together, so it will close properly when the heart is pumping. Only about one in five people who might benefit from this surgery actually get it, because of the risks and rigors of the operation. Many of them might benefit from the new procedure.

A recent study testing the MitraClip looked at 279 people with moderate or severe mitral valve damage in 37 separate North American medical centers. Two-thirds of these people received the clip; the rest received conventional surgery through the chest. Thirty days afterward, there were major complications in 56% of the conventional surgery patients and only in 9.6% of the clip patients. Two of the conventional surgery patients died, two suffered major strokes and four required emergency heart surgery. None of these events occurred in people who received the clip. At the end of a year, valve function was essentially normal in 72% of the clip patients and 88% of the conventional surgery patients.

The researchers point out that surgery works better in the long run (when performing it is feasible), but not so much better that it's clearly the best choice. And if the clip doesn't sufficiently cure a patient's symptoms, surgery can be performed later on.

Unlike most door repair hardware, the clip currently sells for $27,000, plus the cost of surgery. It's approved for use in Europe but not yet generally approved for use in the U.S. The company marketing the clip hopes to get U.S. approval soon.

The study on the MitraClip was presented at The American College of Cardiology's 2010 Annual Scientific Session in Atlanta on March 14.

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