Mitral Valve Repair Or Replacement

The mitral valve sits in the middle of the heart between the two left-sided chambers:the left atrium and left ventricle. It is designed to function as a one-way valve allowing blood to flow from atrium to ventricle and to stop leak of blood backwards.

In developed countries, the commonest reason for needing mitral valve surgery is mitral regurgitation when the valve becomes thinned and leaky allowing for blood to flow backwards. The cause of this valve degeneration is unclear.

In developing nations the commonest cause of mitral valve disease is childhood rheumatic fever that damages the valve and over time, leads to thickening and narrowing or mitral stenosis. Invariably, the symptoms do not appear until adulthood.

Symptoms of mitral valve disease include: shortness of breath, palpitations, swollen ankles and rarely, stroke. If left untreated both mitral stenosis and mitral regurgitation place strain on the heart and can cause it to enlarge and eventually fail.

Mitral valve repair

If at all possible the surgeon will attempt to repair the patient's own mitral valve rather than to replace it with an artificial valve. This will only be performed if the surgeon feels confident that it will restore function to the valve in the long-term.

Hence, only some valve conditions are suitable for mitral valve repair. More commonly, mitral valve repairs are performed on patients with mitral regurgitation due to floppy, thinned leaflets. In this setting it may be possible to remove and tighten some of the mitral valve in order to restore competence. It will then be reinforced with a semi-rigid ring around the outside to support the valve.

In some cases repair of a rheumatic or stenotic mitral valve is possible although these repairs tend to be more challenging and the results not as reliable.

Mitral valve replacement (MVR)

Much of the procedure is identical to coronary artery bypass surgery (which can also be performed at the same time as MVR if required). The breastbone or sternum is cut and the sac around the heart is opened.

The patient is placed on the heart-lung machine or cardio-pulmonary bypass that performs the job of the heart and lungs allowing them to be stopped for the duration of the valve replacement.

The diseased mitral valve is exposed by opening the left atrium which is in back of the heart. Much of the valve is then removed, leaving some of the supporting structures if possible, and the artificial valve is sewn into place.

The heart is restarted and separated from the heart-lung machine. Drain tubes are placed around the heart to monitor bleeding and the breastbone is closed using fine stainless steel wires which hold it in place until the bone is healed (approximately 6 weeks).

Usually, an MVR takes from 5-6 hours. The patient is then taken to the intensive care unit for monitoring. Average hospital stay after AVR is 6-10 days. Recovery from MVR is a gradual process and takes up to 3-6 months.

What Sort of Artificial Mitral Valve is Used?

There are two main types of heart valve used in MVR; mechanical valves or so-called ‘tissue’ valves.

Mechanical valves are made from durable, synthetic materials and barring any malfunctions, will last a lifetime. However, these valves require life-long thinning of the blood or anti-coagulation with tablets called Coumadin, to prevent accumulation of blood clots on the valve. These clots can cause stroke or valve dysfunction. These valves also have a quiet ticking noise related to valve closure, however patients and spouses quickly become acclimatised to this sound.

Tissue or bioprosthetic valves are heart valves taken from animal (usually cow or pig) or human sources. They have been treated to reduce the risk of rejection. These valves do not require blood-thinning therapy but in the mitral position, have a limited life span making them suitable only in elderly patients, unless there are special medical circumstances which preclude the use of blood thinners.

In general, bioprosthetic valves are implanted in older patients especially those over 80 years old. Younger patients will invariably undergo a mitral valve repair, or where not possible, receive a mechanical valve replacement.

Patients should always discuss their own requirements with the surgeon to ensure an operation tailored to their specific health needs.

Minimally invasive surgery

Surgeons are always pushing to minimise the trauma associated with open-heart surgery. In some centres, mitral valve surgery is being performed through smaller incisions and early work is being done on performing this procedure endovascularly or entirely through the groin arteries, similar to a coronary angiogram.

These minimally invasive techniques are not suitable for all valve surgery nor for all patients, and some are only performed in specific centres. Patients should discuss these options with their surgeon prior to surgery.

Mitral valve repair with reinforcing ring

mechanical St Jude mitral valve

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