Mitral valve severe form known as caseous calcification of the mitral valve that can be mistaken for intracardiac mass or thrombus. The closing of the mitral valve and the tricuspid valve constitutes the first heart sound (S1), which can be heard with a stethoscope. It is not the valve closure itself which produces the sound but the sudden cessation of blood flow, when the mitral and tricuspid valves close.. Abnormalities associated with the mitral valve can often be heard when listening with a stethoscope. The mitral valve is often also investigated using an ultrasound scan, which can reveal the size and flow
Mitral valve prolapse "atrialis", "fibrosa", and "spongiosa". Patients with classic mitral valve prolapse have excess connective tissue that thickens the spongiosa and separates collagen bundles in the fibrosa. This is due to an excess of dermatan sulfate, a glycosaminoglycan. This weakens the leaflets and adjacent tissue, resulting in increased leaflet area and elongation of the chordae tendineae. Elongation of the chordae tendineae often causes rupture, commonly to the chordae attached to the posterior leaflet. Advanced lesions—also commonly involving the posterior leaflet—lead to leaflet folding, inversion, and displacement toward the left atrium. Echocardiography is the most useful method of diagnosing a prolapsed mitral valve.