The Mitral Valve

The mitral valve regulates blood flow on the left side of the heart, and is located between the left atrium and the left ventricle chambers of the heart.  The left atrium collects blood that has been oxygenated in the lungs.  As the heart relaxes, this blood flows across the mitral valve and into the left ventricle.  The purpose of the mitral valve is to stop blood from flowing back into the left atrium when the powerful left ventricle contracts.  A properly functioning mitral valve prevents any backward flow, and the blood is then pushed through the aortic valve and to the rest of the body.

The mitral valve is made up of the four main parts: the annulus, the leaflets of the valve, the chordae tendinae, and the papillary muscles.  Together these are known as the "mitral apparatus," and a problem with any one can lead to a poorly functioning mitral valve.  Problems with any part of the mitral valve lead to increased stress on the other structures. 

The mitral valve annulus is a thick band of tissue that encircles the base of the valve and provides a solid foundation for the other structures.  The anterior and posterior leaflets are attached to the annulus.  The leaflets come together when the heart pumps and prevent any backward flow of blood.  The chordae tendinae are cord-like structures that hold the leaflets in place and enable the valve to close tightly.  They attach to muscles in the left ventricle known as papillary muscles.  If the connection between one of the chordae and the papillary muscles is broken, a "flail leaflet" is created.  The flail leaflet does not close properly, and mitral regurgitation (flow of blood across the valve when it should be shut) occurs.  Heart attacks may lead to damage of the papillary muscles, and lead to a "flail" valve.

If the mitral valve becomes damaged, a mitral valve repair procedure should be performed.  Mitral valve repair is perferred over mitral valve replacement, and leads to excellent results in terms of long term function and freedom from re-operation.