disopyramideの投与後，8年を経て再発した多形性心室頻拍症の1例

A Case of a Patient who Had a Recurrence of Polymorphic Ventricular Tachycardia after Continuous Treatment with Disopyramide for 8 Years

　われわれは，disopyramideの投与中，8年を経て再発した多形性心室頻拍症を経験した．症例は53歳，男性で，1989年にQT延長のない多形性心室頻拍による失神発作を繰り返し，disopyramideにより発作は消失した．disopyramideの投与後から心電図前胸部誘導で右脚ブロック型のQRS波形とST上昇を認めたが，失神発作はなく経過した．1997年6月，ホルター型心電図で心室性期外収縮の3連発を認めたため，disopyramideを増量したところ，QT延長を伴って右脚ブロックとST上昇が顕著となり，多形性心室頻拍が再発した．lidocaine,MgSO4の予防効果はなく，右室ペーシングで抑制された．disopyramideの中止後，速やかにQRS-ST波形は正常化し，多形性心室頻拍は消失した．本症例は，disopyramideが右脚ブロックとST上昇，多形性心室頻拍の抑制と増悪に関与した可能性のある1例と思われた．

We describe a patient of polymorphic ventricular tachycardia, who had a recurrence of the complaint after continuous treatment with disopyramide for 8 years. A 53-year-old male was admitted to our hospital because of syncopal attacks in 1989. His electrocardio-gram showed polymorphic ventricular tachycardia at repetitive syncope without QT interval prolongation. Disopyramide. 300 mg/day, was effective to prevent the attack, although right bundle branch block pattern and ST segment elevation in precordial leads became appar-ent. The patient was well until June in 1997, when he was readmitted to our hospital because syncope had recurred. Two days before the second admission, the dose of disopyramide was increased to 450mg/day because follow-up Holter electrocardiogram had shown triplets of premature ventricular contraction. Because of the efficacy of disopyramide for 8 years, intravenous administration of disopyramide was started but the frequency of polymorphic ventricular tachycardia and syncope worsened, while ST segment elevation became more prominent and QT interval prolonged. Right ventricular pacing suppressed ventricular tachycardia, but lidocaine and magnesium sulfate did not. Right bundle branch block pattern, ST segment elevation and QT interval normalized without recurrence of syncope soon after disopyramide was discontinued. Even though the effect of disopyramide such as right bundle branch block pattern and ST segment elevation was evident throughout 8 years, syncopal attack had been suppres-sed. Thus the dose-dependent effect of disopyramide seemed to relate with this characteristic QRS-ST com-plex and the suppression and exacerbation of polymor-phic ventricular tachycardia in this patient.