Pure-Mahaim束による心室早期興奮の2例

2 cases of nodoventricular Mahaim fiber

　心室早期興奮を示す副伝導路にはKent束，James束およびMahaim束があり，その大部分はKent束によるものである。Mahaim束は房室結節下部，ヒス束または脚中枢部と心室とを結ぶ副伝導路^1,2）で，その存在が電気生理学的に確認された報告はKent束やJames束との合併例が多く，Mahaim束単独例の報告は少ない。今回我々はMahaim束単独による早期興奮症候群の2例を経験したので若干の考察を加えて報告する。

Two cases of ventricular preexcitation syndrome using a nodofascicular Mahaim fiber were reported. The electrocardiogram in a 25-year-old man showed normal PQ interval and wide QRS wave with Δ wave. The electrocardiogram in a 45-year-old man showed PQ prolongation (0.28sec) and narrow QRS with very small Δ wave. His bundle electrogram showed short HV intervals in both cases. HV interval shortened and AΔ interval prolonged by atrial pacing and/or atrial extrastimulus with slightly aberration of QRS wave in both cases. In both cases, normal QRS wave with normal HV interval and abnormal QRS morphology with Δ wave and with short HV interval were shown during tachycardia without change in either the cycle length of tachycardia or the atrial activation sequence. These tachycardias were considered AV nodal reentrant tachycardia as bystander.