多彩なQRS波形を呈した心房細動・間歇性右脚ブロック・過常期伝導の1例

Intermittent Right Bundle Branch Block with Supernormal Conduction Showing Various QRS Complexes

　頻脈依存性の間性歇左脚ブロック例における過常期伝導をKinoshitaが報告し，右脚でも同様の現象をKatohらが報告した．今回は72歳男性，心房細動，RR間隔1.16秒を臨界とする頻脈依存性の間歇性右脚ブロック例で，過常期（0.59〜0.63秒）よりもさらにRR間隔が短くなるにつれてそれぞれ0.53秒，0.51秒，0.49秒で右脚ブロック＋著しい左軸偏位，右脚ブロック＋軽度左軸偏位，右脚ブロック＋正常軸が出現した．この現象を理解するためHis-Purkinje系（右脚，左脚前枝，左脚後枝）伝導時間の差として解釈を試み考察した．

　Supernormal conduction in tachycardia-dependent left bundle branch block was reported by Kinoshita, and the same phenomenon in tachycardia-dependent right bundle branch block (RBBB) was reported by Katoh et al.

　In this report, various QRS complexes were documented with shorter RR intervals than in the supernormal phase in a case of tachycardia-dependent RBBB. The critical RR interval and the supernormal phase were 1.16 sec and 0.59～0.63 see, respectively. As the RR interval became shorter than the supernormal phase e.g. 0.53, 0.51, 0.49 seconds, RBBB with marked left axis deviation, RBBB with mild left axis deviation, and RBBB with normal axis, respectively were observed.

　For the undersanding of these various QRS complexes. His-Purkinje conduction times in each heat were speculated.