The mitral valve is the valve located at the junction between the left atrium and the left ventricle. It is a bicuspid valve (having two leaflets, or cusps) that opens during diastole to allow oxygenated blood to flow from the left atrium into the left ventricle, and closes during systole to prevent blood from flowing backwards into the atrium. It is named after the bishop’s mitre, a ceremonial hat whose shape it resembles.
The mitral valve apparatus consists of four components: the two valve leaflets (anterior and posterior), the mitral annulus (the fibrous ring to which the leaflets are attached), the chordae tendineae (thin fibrous cords tethering the leaflet edges to the papillary muscles), and the papillary muscles (ventricular wall protrusions that contract with the ventricle to maintain valve tension). This complex structure ensures the leaflets close precisely with each heartbeat.
Diseases of the mitral valve are among the most common valve conditions in clinical practice. Mitral regurgitation (the valve leaks backwards into the atrium) may be caused by mitral valve prolapse, rheumatic heart disease, or rupture of the chordae tendineae. Mitral stenosis (narrowing of the valve opening) is typically caused by rheumatic disease. Both conditions are assessed by echocardiography and, when severe, treated by mitral valve repair or replacement.
In hypertrophic cardiomyopathy, the anterior mitral leaflet can be drawn towards the left ventricular outflow tract during systole (systolic anterior motion, SAM), worsening outflow tract obstruction and contributing to sudden cardiac arrest risk.
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