慢性の純型・重症僧帽弁閉鎖不全—弁置換44例における臨床的・病因論的検討

Pure, isolated, chronic, severe mitral regurgitation:clinical and etiological studies of 44 cases with mitral valve replacement

　僧帽弁閉鎖不全mitral regurgitation （MR）は，僧帽弁狭窄を合併しない純型のものでもリウマチ性心内膜炎に由来するものが最も多いとされていた^1）。しかし近年はリウマチ熱および炎症性病変が減少し，変性病変に起因するものが増加している^2,3）。

　中年以降のMR例を対象に臨床と病理の両面からその病因を検討した報告は本邦でも稀ではない^4〜6）。しかし弁置換術をうけた純型のMR例を対象とした研究は米国では散見されるが^7,8），本邦ではみられない。

In order to clarify anatomical and etiological bac-kgrounds, 44 patients with isolated, severe, chronic and pure mitral regurgitation who underwent mitral valve replacement were subjected to study on surgi-cally excised mitral valves. Of 44 patients, 35 hadnon-rheumatic disorders ; 23 (52%) rupture of chor-dae including with the echocardiographic findings of mitral valve prolapse in 19. Eight patients (18%) had infectious endocarditis on previously involved mitral valves, and only 9 (21%) rheumatic heart disease. None had mitral regurgitation secondary to papillary muscle dysfunction. Approximately 80% of these 44 patients, therefore, was related to non-rheumatic valvular disease, in the majority of which chordal rupture with myxomatous degeneration of the mitral valve was their main etiological manifes-tations. Non-rheumatic mitral regurgitation severe enough to necessitate mitral valve replacement was found to also be increased in number according to improvement of socio-economical status in this cou-ntry.