Mitral valve repair is a cardiac surgery procedure performed by cardiac surgeons to treat stenosis (narrowing) or regurgitation (leakage) of the mitral valve. The mitral valve is the "inflow valve" for the left side of the heart. Blood flows from the lungs, where it picks up oxygen, through the pulmonary veins, to the left atrium of the heart. After the left atrium fills with blood, the mitral valve allows blood to flow from the left atrium into the heart's main pumping chamber called the left ventricle. It then closes to keep blood from leaking back into the left atrium or lungs when the ventricle contracts (squeezes) to push blood out to the body. It has two flaps, or leaflets.
The techniques of mitral valve repair include inserting a cloth-covered ring around the valve to bring the leaflets into contact with each other (annuloplasty), removal of redundant/loose segments of the leaflets (quadrangular resection), re-suspension of the leaflets with artificial (Gore-Tex) cords. More recently the Alfieri stitch (or "bow-tie") has been adapted to allow percutaneous repair in select patients.
Procedures on the mitral valve usually require a median sternotomy, but advances in non-invasive methods (such as keyhole surgery) allow surgery without a sternotomy (and resulting pain and scar). Minimally invasive mitral valve surgery is much more technically demanding and may involve higher risk.
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 or a bacterial endocarditis. Mitral regurgitation may also occur as a result of ischemic heart disease (coronary artery disease).
In 1923 Dr. Elliott Cutler of the Peter Bent Brigham Hospital performed the world’s first successful heart valve surgery - a mitral valve repair. The patient was a 12-year-old girl with rheumatic mitral stenosis.
The development of the heart-lung machine in the 1950s paved the way for replacement of the mitral valve with an artificial valve in the 1960s. For decades after, mitral valve replacement was the only surgical option for patients with a severely diseased mitral valve. However, there are some significant downsides to an prosthetic mitral valve. Infection of the valve can occur, which is dangerous and difficult to treat. Patients with mechanical heart valves are required to take blood thinners for the rest of their lives which presents a risk of bleeding complications. The artificial mitral valve has an elevated risk of stroke. Finally, artificial tissue valves will wear out - on average lasting between 10 and 15 years, requiring further surgery at an advanced age.
In the past two decades, some surgeons have embraced surgical techniques to repair the damaged native valve, rather than replace it. These techniques were pioneered by a French heart surgeon, Dr. Alain F. Carpentier. A repair still involves major cardiac surgery but for many patients presents the significant advantage of avoiding blood thinners and may provide a more durable result. Not all damaged valves are suitable for repair; in some, the state of valve disease is too advanced and replacement is necessary. Often, a surgeon must decide during the operation itself whether a repair or replacement is the best course of action.
There has been great debate about timing of surgery in patients with asymptomatic mitral valve regurgitation. There are minimally invasive (port access) options available pioneered by Hugo Vanerman in Belgium. These methods may be safer, and allow the patient to return to their normal activity much sooner than the standard approach. Robotic mitral valve repair operations are also being tested at some medical centers.
In the 2000s there have been several trials of a newer strategy of mitral valve repair that does not require major cardiac surgery. Through a catheter inserted in the groin, the valve leaflets are clipped together. This technique - percutaneous mitral valve repair - remains under trial, is very specialized and is only available at a select number of hospitals worldwide.