切除僧帽弁標本の外科解剖—特に疾患別障害部位の特徴について

Surgical anatomy of the resected rheumatic mitral valves

　僧帽弁膜症は心臓外科初期から手術対象となった疾患であり，交連切開術をはじめ，弁形成術の適応範囲は広い。最近では良好な人工弁の開発にともない人工弁置換術が選択される趨勢になってきてはいるが，人工弁治療にはいぜんとして問題点も指摘され，できるだけ自己弁を温存しようとする弁形成術もまた多くの施設で選択されている。弁形成術の問題は，術後長期におたり修復した弁組織が良好な弁機能を維持しうるかどうかであり，術式選択に際しては修復すべき弁病変を正確に把握し，修復後の経過および予後を知ることが必要である。

　このためには，詳細な弁病変の検討が必要となるが，僧帽弁膜症の弁形態は多彩であり，しかも，従来弁病変の表現として用いられてきた「短縮」・「癒合」・「肥厚」・「石灰化」などでは，個々例の弁形態の表現には適切であっても，他の症例との比較が容易になしえないという限界があった。更に，これらの表現では弁病変の時間的推移を観察することは難しく，「弁形態形成過程」の検討は十分に必要であることはわかっていても，積極的な研究対象となりえなかったのが現状であった。

The characteristic features of 43 rheumatic mitral valves removed at surgery were studied. Four groups of NIS, MSr, MSR and MR were classified on the basis from preoperative physical examination, cardiac catheterization and especially degrees of mitral regurgitation obtained by left ventriculo-graphy. The measurements of various valve structures, such as valve annulus, valve orifice, valve leaflets, commissures and chordae tendineae were made of each valve. The extent of calcification determined by radiograph. These values obtained by measurement were compared among 4 groups by means of the statistical analysis. MS was charac-terized by ① shortening of intercommissural distance, ② thickening of the anterior commissure, ③ multiple calcification especially in the posterior leaflet and the posterior commissure and ④ fusion and shortening of chordae tendinea (especially shortening of the posterior strut chorda). MSr was characterized by ① calcification involved a single site (mainly in the posterior leaflet) and ② short-ening of the anterior strut chorda. MSR was characterized by ① thickening of both anterior and posterior commissures, ② posterior leaflet thinner than anterior one, ③ the height of posterior leaflet shorter than that of the anterior leaflet, ④ tendency towards multiple calcification and ⑤ milder sub-valvular lesions as compared with MS and MSr. MSR differed from MS chiefly in the followings, e : that intercommissural space was expanded, that the height of the posterior leaflet was diminished and that the change in chordae as a subvalvular lesion was slight. MR was characterized by dilation of the annulus, which constituted the chief lesion. The height of the posterior leaflet decrease and the thickening of the posterior leaflet was mild. Calcification was absent in it, and chordae were lengthened as compared with those in the other diseases. Mitral valve diseases associated the aortic valve disease were characterized by widening of the intercommissural distance, increase in the height of the anterior leaflet and absence of calcification i n the anterior leaflet compared with single mitral valve diseases.