Mitral valve repair a 12-year-old girl with rheumatic mitral stenosis. The development of the heart-lung machine in the 1950s paved the way for "replacement" of the mitral valve with an artificial valve in the 1960s. For decades after, mitral valve replacement was the only surgical option for patients with a severely diseased mitral valve. However, there are some significant downsides to a prosthetic mitral valve. Infection of the valve can occur, which is dangerous and difficult to treat. Patients with mechanical heart valves are required to take blood thinners for the rest of their lives, which presents a risk of bleeding complications. The
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.