What is mitral regurgitation?
The mitral valve is a heart valve that lies between the left atrium and left ventricle. It allows blood to flow into the left ventricle when the left atrium squeezes (contracts). However, when the left ventricle contracts, the mitral valve closes and the blood flows out through the aortic valve into the aorta. (The aorta is the main artery which takes blood to the body.)
The mitral valve has two flaps (cusps). The cusps are prevented from turning inside out by thin strands of tissue called chordae. The chordae anchor the cusps to the inside wall of the ventricle. The valve or chordae may become damaged or scarred which can prevent the valve from working properly. This can lead to disorders called mitral stenosis, mitral regurgitation, or a combination of these two. Read more about mitral stenosis.
Mitral regurgitation is sometimes called mitral insufficiency or mitral incompetence. In mitral regurgitation the valve does not close properly. This causes blood to leak back (regurgitate) into the left atrium when the left ventricle squeezes (contracts). Basically, the more open the valve remains, the more blood regurgitates and the more severe the problem.
Mitral valve prolapse
This is also called floppy mitral valve. In this condition the valve is slightly deformed and bulges back into the left atrium when the ventricle contracts. This can let a small amount of blood leak back into the left atrium. As many as 1 in 20 people have some degree of mitral valve prolapse. It most commonly occurs in young women. It usually causes no symptoms, as the amount of blood that leaks back is often slight. The cause of most cases of floppy valve is unknown. It sometimes occurs with connective tissue disorders such as Marfan's syndrome.
What effects does mitral regurgitation have?
As the valve does not close properly, some blood is pumped back into the left atrium when the left ventricle squeezes (contracts). Minor leaks do not matter much.
However, with larger leaks, it causes an increase in the pressure in the atrium. Therefore, the wall of the atrium may become thicker (hypertrophy) and the atrium may enlarge (dilate). A 'back pressure' of blood may then cause congestion of blood in the blood vessels which bring blood to the left atrium (the pulmonary veins which bring blood from the lungs).
Also, if a lot of blood leaks into the left atrium when the left ventricle contracts, less blood is pumped into the body via the aorta. The heart compensates for this. The wall of the left ventricle may become thicker, the ventricle may enlarge and the heart rate may increase.
What are the treatments for mitral regurgitation?
Mild cases may not require any regular medication. Although medicines cannot correct mitral regurgitation, some medicines may be prescribed to help ease symptoms, or to help prevent complications - for example, angiotensin-converting enzyme (ACE) inhibitors, 'water tablets' (diuretics) and anticoagulation medication. If you develop atrial fibrillation, several medicines can be used to slow the heart rate down.
Surgical treatment is sometimes needed. Recent guidelines favour surgery at an earlier stage than used to be the case.
- Valve repair may be an option in some cases.
- Valve replacement is needed in some cases. This may be with a mechanical or a tissue valve. Mechanical valves are made of materials which are not likely to react with your body, such as titanium. Tissue valves are made from treated animal tissue, such as valves from a pig.
Recent guidelines favour replacement rather than repair in many cases. If you need surgery, a surgeon will advise on which is the best option for your situation.
Antibiotics to prevent endocarditis
People with mitral regurgitation used to be given antibiotics before some dental treatments and some surgical operations. However, the National Institute for Health and Care Excellence (NICE) no longer recommends that they be taken routinely for any of these procedures. Antibiotics are now only offered to people who have an infection at the time of the operation.
What is the outlook for people with mitral regurgitation?
In some cases, the disorder is mild and causes no symptoms. If you develop symptoms they tend to become gradually worse over the years. However, the speed of decline can vary. In many cases, it can take years for symptoms to become serious. Medication can ease symptoms but cannot reverse a damaged valve.
Surgical treatment has greatly improved the outlook in most people with more severe regurgitation. Surgery has a very good success rate.
Further reading and references
Nishimura RA, Otto CM, Bonow RO, et al; 2017 AHA/ACC Focused Update of the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease. Circulation. 2017 CIR.0000000000000503. Originally published March 15, 2017.
2015 ESC Guidelines for the management of infective endocarditis; European Society of Cardiology (Aug 2015)
Vahanian A et al; Guidelines on the management of valvular heart disease: The Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology, 2017.
Ozkan M; What is new in ACC/AHA 2017 focused update of valvular heart disease guidelines. Anatol J Cardiol. 2017 Jun17(6):421-422. doi: 10.14744/AnatolJCardiol.2017.7925.
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