超音波断層心エコー法による小児期心房中隔欠損症の左室形態と局所壁運動の検討

Assessment of Left Ventricular Shape and Wall Motion by Two-dimensional Echocardiographic Study in Children with Secundum Atrial Septal Defect

　二次口型心房中隔欠損症（ASD）患児に対して超音波断層心エコーを行い，左室局所壁運動をパターン化して左室特性を明らかにすることを試みた．対象は他に合併心奇形のないASD患児19例で，これらをほぼ同時期に施行した心臓カテーテル検査により得られた肺体血流比（Qp／Qs）に従い2群に分類し（A 1群＜2.0,A 2群≧2.0），検討を行った．左室短軸像における拡張末期面積，面積駆出率，1回拍出面積は低値を示し，いずれもA2群ではその程度が大きかった．局所壁運動は心室中隔および側壁の壁運動の低下を特にA2群において認めたが，前壁および後壁の壁運動はAl群では亢進し，A2群でも保たれていた．左室短軸像はQp／Qsが増大するに従い拡張末期および収縮末期ともに扁平化を示すが，拡張末期像では扁平化の度合いが大きく，左室形態の変化が局所壁運動に影響を与えているものと思われた．

We performed two-dimensional echocardiography to evaluate the left ventricular (LV) function and the regional LV wall motion in 19 children with secundum atrial septal defect (ASD). These were classified according to the degree of left-to-right shunt into small (flow ratio ＜2.0 : group A1), large (flow ratio≧2.0 : group A2). We also evaluated that of 18 cases with Kawasaki disease showing normal findings in the coro-nary angiogram (Group N).

Short axis study revealed the end-diastolic area of LV and the ejection fraction of LV to be slightly de-creased in groups A1 and A2, while group N was nor-mal. The left ventricular wall motions in both groups Al and A2 were lower especially around the septal and lateral regions. But the LV wall motions in those groups around the anterior and posterior regions were better than those of group N. In patients of groups A1 and A2, the LV cavity was distorted at the end-diastole and became circular at end-systole. Because of this characteristic change during systole, the end-diastolic area of LIT and the ejection fraction of LV were slightly lower in ASD groups than in those in group N. This study suggests that abnormal regional LV wall motion in patients with right ventricular volume overload is a result of a change in the shape of the left ventricle.