林田 晃寛, 土岐 美沙子, 木村 晃久, 吉田 清

Akihiro HAYASHIDA, Misako TOKI, Akihisa KIMURA, Kiyoshi YOSHIDA

心臓病センター榊原病院循環器内科

Department of Cardiology, The Sakakibara Heart Institute of Okayama

キーワード : wall motion, ischemic heart disease, cardiac sarcoidosis, method of disks, Simpson’s rule

左室壁運動を評価するためには，左室を正しい断面で描出しなければならない．心尖部が真の心尖部になっておらず，左室の大きさを過小評価していることは多い．エコーベッドを用いたり，呼気時だけではなく吸気時にも撮像して，なるべく左室の長軸径が大きくなるようにする．短軸は乳頭筋レベルで観察を行い，両方の乳頭筋が均等に描出されているかを確認する．均等ではないと斜め振りの可能性あり，壁運動評価が正当にできない．短軸，及び心尖部からの長軸像で局所壁運動異常と心筋の性状を評価する．陳旧性心筋梗塞では，内膜側の輝度上昇，壁厚減少も重要な所見である．冠動脈支配領域に一致しない場合は，心サルコイドーシス，たこつぼ型心筋症などを考える．その際は，心電図も参考にする．左室収縮能評価は，Method of disks （MOD） 法で行う．これは，左室を20個の楕円柱に分割して体積を求める方法である．心エコーの機械でMODと表示されるため，modifyの略と誤解している人も多いが，これは誤用である．

The left ventricle must be depicted in the correct cross-section to assess left ventricular wall motion. Often, the apex is not a true apex, and the left ventricle size is underestimated. The long axis of the left ventricle should be enlarged as much as possible by using an echo bed or by imaging during inspiration as well as expiration. The short axis should be observed at the level of the papillary muscles to make sure that both papillary muscles are equally delineated. If they are not equal, there is a possibility of oblique swing, and wall motion evaluation cannot be done properly. Regional wall motion abnormalities and myocardial properties on short-axis and long-axis images from the apex should be evaluated. In old myocardial infarction, increased intensity and decreased wall thickness on the intimal side are also important findings. If the findings are not consistent with coronary artery supply, cardiac sarcoidosis or takotsubo cardiomyopathy should be considered. In such cases, the electrocardiogram should also be referred to. Left ventricular contractility is assessed using the method of disks (MOD). This is a method for determining the volume of the left ventricle by dividing it into 20 elliptical columns. Many people misunderstand MOD as “modify" because it is displayed on echocardiography machines, but this is a misnomer.