超音波心断層法による僧帽弁狭窄病変の評価及び左室造影所見との対比

Evaluation of the mitral valve and subvalvular structures in pure mitral stenosis by cross-rectional echocardiography

はじめに

　僧帽弁狭窄症の手術時期の決定には，術前における術式の予測，即ち弁の温存が可能か否かの判定が極めて参考となる。この目的のためには，従来の左室造影法に加えて^1,2）近年開発された超音波心断層法の有用性が検討されている^3〜5）。著者らも，左室造影法及び超音波心断層法による僧帽弁病変の評価を試み，すでに報告してきたが^6,7），従来の超音波心断層像による程度判定には，画像の条件や検者の主観的判断に左右されていささか客観性を欠くきらいがあった。そこで今回著者らは，超音波心断層法による僧帽弁病変の定量的評価を試み，さらにこれを左室造影法による数量的評価と対比することによってその診断的価値を検討した。

In order to evaluate the mitral valve and sub-valvular lesion, quantative and semi-quantative studies were performed in 31 cases with pure mitral stenosis by cross-sectional echocardiography. As the semi-quantative study, mitral structures were separated into 6 parts, each of which was classified into 3 grades according to the echocardio-graphic findings and scored by points (mild... 1 point, moderate... 2 points and severe 3 points). As the quantative study, movement ratio (2D･MR) of anterior mitral leaflet (AML) was calculated from the long axis cross-sections (the difference in the distance from the mitral annulus to the tip ofAML between mid-systole and early-diastole was divided by the mitral annulus diameter for stand-ardization).

The result obtained from cross-sectional echo-cardiographic evaluation and the surgical pro-cedures applied to these patients were in good correlation, and the index of 2D･MR was signifi-cantly higher and that of point score was significant-ly lower in cases of open mitral commissurotomy (OMC) than those of mitral valve replacement (MVR). OMC was successfully performed when patient's point score was less than 16 and 2D･MR more than 0.20.

In addition, the cine-angiographic findings of mitral valve pliability ratio and mitral subvalvular distance ratio, which were reported in recently, were well correlated to these echocardiographic findings.