The mitral valve is found on the left side of the heart. It connects the collecting chamber or the left atrium to the pumping chamber or the left ventricle. This is commonly affected by rheumatic heart disease in the Asian subcontinent and by degenerative disease in the western world.
The mitral valve is made of two leaflets that are well supported in their structure and function by chords and papillary muscles of the heart. The normal area of opening is 3.5 sq.cm when this area is less than 0.8sq.cm then the valve is said to critically stenosed and requires urgent attention. Any malfunction of the mitral valve can cause a back pressure on the blood vessels of the lungs resulting in increased pressures in the lungs and eventually right heart failure. This is one of the reasons early treatment of mitral valve disease has better results and lesser morbidity.
Frequent episodes of rheumatic activity triggered by strep throats can cause an inflammation of the mitral valve leaflets leading to Thickening or stiffening of the leaflets Shrinkage of the chords that hold the leaflets and their thickening The above mentioned two processes can cause stenosis of the valve leading to back pressure in the left atrium and transmitting the pressure into the lungs. They can also cause the leaflets to be pulled apart and make the valve leaky. This will cause the heart to enlarge and eventually lead to heart failure. This is easily repairable and the earlier one does it the lesser the risk and greater the benefit.
The degeneration of the connective tissue framework of the valve results in the leaflets becoming loose and floppy. The floppy leaflets have poor approximation and result in a leaky valve. Mitral valve prolapse (MVP) is a type of myxomatous valve disease. MVP causes the leaflets of the mitral valve to flop back into the left atrium during the heart’s contraction. MVP also causes the tissues of the valve to become abnormal and stretchy, causing the valve to leak. MVP occurs in about 1 to 2 percent of the population, equally in men and women. Most often it is not a cause for concern. Only 1 in 10 patients with MVP eventually require surgery. If the prolapse becomes severe or is associated with torn chordae or flail (floppy, lacking support) leaflets, the leak may be greater, requiring surgical intervention.
The mitral valve is supported in its function by chordae tendinae which are thin strands that connect it to the papillary muscles which are outpouchings from the left ventricle muscle and together these go to play an important part in the mechanics of the mitral valve. When one of these is damaged the valve is pulled apart and can leak profusely. These can be damaged by Ischemia or heart attack or trauma. If the chordae become torn or papillary muscles become stretched or torn, the leaflets may flop backward when the ventricles contract (flail leaflet), causing a leaky valve.
