運動誘発性心室頻拍の5例—運動負荷による再現性の意義および電気生理学的検討

Five cases of exercise-induced ventricular tachycardia:Reproducibility and electrophysiologic properties of exercise-induced ventricular tachycardia

　虚血性心疾患にみられる心室頻拍（VT）をはじめとした持続性VTの多くがリエントリー機序によると考えられ，これらに対し電気生理学的検査（EPS）は薬物療法や外科治療のガイドラインとして確立されている^1）。

　一方，運動で誘発されるVTは明らかな器質的異常を認めないこともしばしばで非持続性のものが多い^2〜4）。虚血やカテコルアミンの関与が考えられているがEPSを加えた報告は少なくVTの機序や予後など不明の点が多い^2〜5）。

　今回我々は持続性運動誘発性VT 3例を含む5例の運動誘発性VTに対し，運動負荷検査によるVTの再現性および薬剤の効果について検討し，さらにEPSによる機序の検討も行ったので報告する。

Five cases of exercise-induced ventricular tachy-cardia (VT) were presented. VTs occurred during or immediately after Treadmill exercise testing and lasted from 20 sec to 8 min, resulting in syncopal attack in one case. Electrocardiograms of VTs sho-wed monomorphic characteristics ; right bundle bran-ch pattern and left axis deviation (RBBB-LAD) in two cases, left bundle branch block pattern and infe-rior axis (LBBB+IA) in two cases, and RBBB+ IA in one case. The rate of VT with RBBB+LAD incre-ased gradually with exercise, whereas other forms ofVT showed constant rate ; 210 bpm in average. Reproducibility of VT and critical heart rate, above which VT intiated spontaneously, was observed without exception. Sustained VT was induced and terminated reproducibly by programmed electrical stimulation (PES) in cases with VT with RBBB+ LAD. In other cases, non-sustained VT only was induced by PES. Spontaneous VT occurred with Isoproterenol infusion in one case. Propranolol was effective in one case, Procainamide in one case and Verapamil in two cases. It is concluded that in our five cases, exercise-induced VT lasting for 20 sec or more had a common finding of critical heart rate-VT relationship, however, electrophysiologic proper-ties of VT or efficacy of drugs on VT were not the same.