The mitral valve (bicuspid valve) is a thin membrane that is located between the left upper (atrium) and lower (ventricle) chambers of the heart. Along with the tricuspid valve, it is also called as the atrioventricular valve. It has two cusps or leaflets. It prevents backflow of blood from left ventricle to the left atrium during the contractions of the heart. A fibrous ring of muscle surrounding the valve is called mitral valve annulus.
Pressure increase due to upper chamber contraction opens up the valve and lets the blood flow from the left atrium to the left ventricle. When the lower chamber contracts, the mitral valve closes and prevents the back flow of blood into upper chamber. The upturn or prolapse of the valve to the other side is prevented by small muscle projections from the wall of the left ventricle (papillary muscles) that attach to these cusps via the cord-like tendons (chordae tendineae).
Problems affecting mitral valves:
• Prolapse – abnormally thickened and floppy valve leaflet don’t close tightly and valve collapses into upper chamber leading to backflow of blood
• Regurgitation – full closure of valve prevented causing backflow of blood. It could be due to valve prolapse, widening of the annulus, congenital heart defects, etc.
• Stenosis – narrowing of valve due to thickening which restricts blood flow
Physical examination, auscultation, blood tests, ECG, echocardiography, angiography, etc. can aid in diagnosing valve conditions. Treatment is aimed at reducing symptoms, protecting the valves from further damage, valve repairing and/or valve replacement. Medications, valvuloplasty, surgery, etc. are some of the treatment options.