1982 年 46 巻 4 号 p. 369-376
Mitral valve prolapse is diagnosed in real-time two-dimensional echocardiograms when there are discrepancies in the coaptation zone of the anterior mitral leaflet and the posterior mitral leaflet. Out of the 100 cases of mitral valve prolapse diagnosed in this way, 65 had prolapsed anterior mitral leaflets, 28 prolapsed posterior mitral leaflets and 7 prolapses of both the anterior and posterior mitral leaflets. In addition to the cases with mitral valve prolapse, 23 cases of ruptured chordae tendineae of the mitral valve, including 15 cases which had undergone surgery, were investigated. The frequent site of mitral valve prolapse was the posteromedial commissure in the anterior leaflet and the posteromedial and anterolateral commissures in the posterior leaflet. These sites coincide with those where rupture of the chordae tendineae of the mitral valve was apt to occur. An investigation of the relation between age and mitral valve prolapse showed that the number of cases of prolapsed anterior leaflet did not increase with age, but there was an age-related increase in the number of cases of prolapsed posterior leaflets. It was also found that the degree of the prolapse progressed with age. Many of the cases of ruptured chordae tendineae of the mitral valve were in their forties or fifties, and there appeared to be some relation between the progress of the prolapse and age. Mitral regurgitant murmurs were recorded on phonocardiograms, and the severer the degree, the wider the range of the prolapse. Mitral regurgitation was more likely to occur in cases of prolapsed posterior leaflets than in those with prolapsed anterior leaflets, even if the degree and the range of the prolapse were mild.
