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Mitral Valve Repair
The most common type of heart valve repair is mitral valve repair.
The mitral valve separates the left atrium from the left ventricle.
Image from AHA
The mitral valve gets its name from a similarity to the miter hat worn by bishops.
A stiff or leaky valve will often caused abnormal blood flow through it, which creates a murmur.
A murmur is the abnormal sound - but it may or may not represent a disease or a problem that needs to be fixed. Sometimes, mitral regurgitation (MR) is first found because a healthcare provider hears a murmur.
Listen to NORMAL HEART SOUNDS
Listen to MITRAL REGURGITATION MURMUR
The amount of stiffness or leakage is usually determined using a fancy ultrasound, called an ECHOCARDIOGRAM.
The mitral valve can become stiff and thickened and tight, which is called stenotic. Mitral stenosis is fairly rare in 2019 in the US. It can be caused by rheumatic fever.
A stenotic mitral valve usually must be replaced rather than repaired.
But most mitral valves that leak can be repaired and do not require replacement.
An ECHOcardiogram is often confused with an ELECTROcardiogram.
To keep them straight, just remember ECHO uses sound waves to look at the valves and ELECTRO looks at the electricity of the heart rhythm
ECHO
EKG
The ECHO will show how much stiffness aka stenosis, or how much leakage aka insufficiency, the valve may have.
The amount of stenosis or insufficiency may be NONE TRACE MILD MODERATE or SEVERE.
In general, mitral valves need to be repaired if there is SEVERE insufficiency, and especially if the patient is having symptoms, or if the heart is becoming weak.
Unlike the aortic valve which has only 3 moving parts, the mitral valve has many parts, which fit together in complex ways. Repairing the mitral valve can be difficult in the sense that changing one part of the valve can cause shifting in another part of the valve.
When it comes to planning a mitral valve repair operation, knowing exactly which part of the valve is not working correctly is important.
On of the most common mechanisms of MR is a ruptured chord.
The chordae are like parachute strands that keep the valve leaflets from prolapsing up too high and allowing blood to leak back thru the valve.
The chordae are under high stress and can break.
The body cannot fix a ruptured chord, nor can medications. An operation is required in order to repair the damage. A synthetic new chord made of Gortex can be placed. And there are other ways to repair the valve if needed.
Other parts of the valve can also break. The method to repair the valve will depend on the specific part that is broken.
In general, it is desirable to repair the mitral valve rather than replace it, whenever possible. In medical shorthand, this is written as MVr - Mitral Valve repair. A replacement would be written MVR.
If a mitral valve needs to be repaired, there are a couple of options on how it can be done:
STERNOTOMY
MINIMALLY-
INVASIVE
MitraClip
A sternotomy is the "usual" method for MVr. The breastbone is cut from top to bottom.
This allows access to all areas of the heart and multiple procedures on the heart can be performed, if needed.
If a patient requires MVr and bypass grafts, then a sternotomy is usually required and a minimally-invasive method cannot be used.
Most patients tolerate a sternotomy well.
It usually takes Dr. Pool 2-3 hours to perform an MVr thru a sternotomy.
Dr. Pool recommends not driving for 2 weeks after sternotomy. And no lifting over 10 lbs for 2 months. After 2 months, the breastbone will be healed and most patients have no restrictions at that point.
A minimally-invasive method can often be used for MVr.
The method Dr. Pool uses involves a small incision between the ribs in the right chest.
It may seem odd to go thru the right chest to get to the mitral valve since the heart is slightly to the left in the chest, but access thru the right chest allows for excellent visualization of the valve. It is very rare to attempt to access the mitral valve thru the left chest.
If a patient requires MVr and bypass grafts, then a sternotomy is usually required and a minimally-invasive method cannot be used.
In addition to the incision in the right chest, there is also a small incision in the groin. This incision is used to facilitate the heart and lung machine.
It usually takes Dr. Pool 2-3 hours to perform a minimally-invasive MVr.
Dr. Pool does not usually recommend a minimally-invasive approach for very large patients or for patients who have a very weak heart.
Dr. Pool recommends not driving for 1 week after a minimally-invasive MVr. And no lifting over 10 lbs for 6 weeks.
The stiff old valve provides friction with the new valve, which holds it in place.
The least invasive method for repairing the mitral valve is implantation of the MitraClip.
The Clip is like a very fancy clothespin that holds the leaky portion of the valve together.
This procedure is also called transcatheter mitral valve repair.
With MitraClip, no open incision is needed at all. A Clip is put in thru a vein in the groin. It is guided into position in the heart and released.
There are no sutures holding the Clip in place.
The FDA has approved MitraClip only for certain patients, usually patients who are elderly or frail or have high risk for a traditional MVr.
Dr. Pool is part of a team of experts at Texas Health Dallas who help determine which patients are eligible for MitraClip.
Some mitral valves cannot be repaired and must be replaced. This is definitely true for stenotic valves but can occur with valves that leak, if the valve is broken in an unusual way.
If a mitral valve needs to be replaced, there are options on what kind of valve to put in:
MECHANICAL VALVE
TISSUE VALVE
A mechanical valve is made out of metal. Actually, the mechanical valve Dr. Pool usually uses is not made of metal, but is made of carbon (called On-X valve).
A mechanical valve has parts that move in a way that allows for blood clots to sometimes form in the valve. If a blood clot forms, it can go to the brain and cause a stroke. So mechanical valves require a blood thinner to be taken, to avoid blood clots.
The benefit of a mechanical valve is that it is expected to last "forever," or at least, it is not expected to wear out. In theory, a mechanical valve could last for 50 years or more.
On rare occasion, a mechanical valve can get clogged or break, in which case it may need to be replaced.
The blood thinner needed for mechanical valves is coumadin, also known as warfarin. Blood levels - known as the INR - must be checked to be sure the correct amount of blood thinning.
Young patients - those in their 20s or 30s - often elect for a mechanical valve. A mechanical valve is not usually placed for older patients.
A tissue valve is made from tissue - that is, from an animal. There are pig, horse, and cow valves available. The fancy term for this type of valve is xenograft.
The drawback for a tissue valve is that the valve will eventually wear out. The tissue valve that Dr. Pool usually uses for MVR is expected to last about 15 years.
A tissue valve has been processed in a way that the patient's body will not reject it. The patient does not usually need to take any special medicines because of a tissue valve, and usually the patient does not require a blood thinner for a tissue valve.
Any type of new heart valve - mechanical, tissue, TAVI, human - can become infected. Fortunately, this does not happen often. But when a replaced valve become infected, it usually requires another operation to replace it again, in order to get rid of all of the infection.
Mitral Regurgitation
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