The mitral valve separates the left ventricle from the left atrium. It acts like all valves in the heart-- as a one way valve. This allows the blood to flow forward when the heart contracts and prevents leaking back into the left atrium as the heart relaxes between each contraction. The valve is composed of two leaflets which look, with the eye of faith, like the mitre the Pope wears-- hence the mitral valve.
The valve can become leaky (mitral regurgitation or MR) and this can cause the blood to leak into the left atrium. Patients can become more breathless as a result. In some patients it can cause the heart rhythm to become irregular. Breathlessness and palpitations are the main symptoms. Some patients can have mild to moderate degrees of leakiness of the valve and have no symptoms at all. The reasons for the leaking valve are several. The left ventricle can enlarge in conditions such as heart failure and this can lead to valve stretching and thus not closing tightly enough. The leaflets can become more floppy and prolapse back. In more dramatic cases the valve can become leaky after a heart attack or after an infection affecting the valve itself (endocarditis).
The valve can become narrowed (mitral stenosis or MS). This can be related to rhematic fever as a child. Some patients are born with a narrowed valve. Patients can present with breathlessness and palpitations. It can be undiagnosed for years and present when the heart is having to work harder, such as in pregnancy.
The treatment for a leaky valve if the degree is severe enough usually involves open heart surgery. There are many patients with varying degrees of MR that simply need to be monitored for a period of time and can be managed well on medication for many years. In assessing the degree of leakiness a patient may require and angiogram which also focusses of the right heart pressures. They may also require a special type of echocardiogram called a transoesophageal echo. Recently there has been some cases of a mitral valve clip that can be used to reduce the leakiness which can be done via a procedure through an artery in the leg.
A narrowed valve may also require a surgical operation depending on the degree of narrowing. A balloon procedure that is performed from the leg is also possible in some patients.
With mitral valve disease monitoring of the valve with serial echocardiograms (ultrasounds of the heart) is important. The timing of heart surgery is important especially in mitral regurgitation.