心筋病変を有した心室頻拍の女児

Ventricular Tachycardia Assciated with Abnormal Myocardial Tissue

　症例は5歳の女児で，繰り返す運動時の意識消失発作を主訴に受診した．Holter心電図で歩行時に非持続性心室頻拍（non-sustained ventricular tachycardia，VTと略す）を認めたため，運動誘発性のVTが意識消失（Adams-Stokes発作）の原因と考えてメキシチール，ジソピラミドにて治療を開始した．しかし，内服後もAdams-Stokes発作を繰り返すため電気生理学的検査を行ったが，電気刺激やイソプロテレノール負荷でVTは誘発されなかった．プロプラノロールがVTと心室性期外収縮（VPC）に抑制的に作用することが確かめられたため，プロプラノロール内服（2mg/kg）にて外来治療を行った．しかし，プロプラノロール内服にてもAdams-Stokes発作を生じ，トレッドミル運動負荷（TMET）にて非持続性VTが誘発されたためフレカイニド（100mg/m²/日）による治療に切り替えた．その結果，short runは散発するものの洞調律の時間帯が大幅に増加し，Adams-Stokes発作も消失した．本症例では突然死の家族歴や特発性心筋症などの既往はなかったが，右室心筋生検で心筋症様の組織変化を認め，VT発生に心筋病変が関与している可能性が示唆された．

　We report a 5-year-old girl who had several Adams-Stokes attacks due to ventricular tachcardia (VT) during a period of 8 months befor admission to our hospital. The first attack of loss of consciousness took place while she was running at the age of 4 years. Electrocardiogram showed ventricular bigeminy and Holter ECG non-sustained VT. In order to prevent Adams-Stokes attack, we first used mexilletine and disopyramide, but in spite of the use of these anti-arrhymic agents, Adams-Stokes attacks did not cease. On electrophysiological study, exercise-induced VT was not evoked but propranolol was effective in reducing VT on exercise. Microscopic myocardial abnormalities similar to those found in cardiomyopathy were observed in right ventricular myocardial biopsy. Adams-Stokes attacks were finally prevented by the use of flecainide.