徐脈，QT延長および失神発作を認め，ペースメーカー治療が有効であった2症例

Two cases of prolonged QT interval and syncopal attacks treated with ventricular pacemaker

　心電図上QT時間が延長する原因は，1次性と2次性に分けられる。1次性には遺伝的要素を持ち，聾唖を伴い常染色体性劣性遺伝するJervell-Lange-Nielsen症候群1）と聾唖を伴わず常染色体性優性遺伝するRomano—Ward症候群2）が報告され，いずれも失神発作をくり返し，しばしば突然死に至る。一方，2次性のものには種々な病態が含まれるが，高度の房室ブロックあるいはSick sinus syndromeによる徐脈によりQT延長を来たすことが知られている。著者らは最近，比較的若年でありながら，徐脈に伴い著しいQT延長と心室性不整脈を生じ，恒久型ペースメーカーの植え込みを施行した2症例を経験したので報告する。

Two cases with prolonged QT interval were de-scribed. They demonstrated no familial history of QT prolongation.

Case 1 was a 17 year-old woman. She was ad-mitted to the hospital after several spells of uncon-sciousness. Electrocardiogram showed atrioventri-cular dissociation with a ventricular rate of 55/min with marked prolongation of QT interval (QTc : 0.68 sec). On the basis of the electrocardiographic find-ings, the spells of unconsciousness were diagnosed as syncope due to polymorphous ventricular tachycar-dia. Cardiac catheterization and biopsy showed at-rial septal defect and myocardial fibrosis. She was successfully treated with a permanent pacemaker.

Case 2 was a 22 year-old woman. She had several spells of unconsciousness. During hospitalization, she felt faintness associated with bradycardia. Electrocar-diogram showed sinus bradycardia (rate 42 beats/min) with prolongation of QT interval (QTc : 0.61 sec) and ventricular extrasystole. She did not have any organic heart disease, but had anorexia nervosa. She was also treated with a permanent pacemaker. Thereafter, they had no spell of unconsciousness. QT interval of spontaneous rhythm decreased after ventricular pacing in these patients. Thus, ventricu-lar pacing might be an effective treatment in patients with QT prolongation especially due to bradycardia.