両脚ブロック例の電気生理学的検討

Electrophysiological study of cases with bilateral bundle branch block

　完全房室ブロックを病理学的に検索すると多くの例で右脚および左脚の両脚に変性，線維化，石灰化など種々の程度の障害がみられることが報告されている^1〜3）。従って右脚，左脚の両脚における伝導障害，すなわち両脚ブロックを診断し，適切な管理を行うことは完全房室ブロックの発生やAdams-Stokes発作の出現に関連し重要と思われる。現在まで両脚ブロック，主として交代性脚ブロックについては房室伝導障害が進行性であるという報告はあるが^2〜8），詳細な電気生理学的検討がなされた報告は少ない。今回我々は2例の交代性脚ブロックを含む3例の両脚ブロックの症例につき電気生理学的所見を中心に報告する。

Electrophysiological studies (EPS) were per-formed in 3 cases of bilateral bundle branch block (BBBB). Case 1 was a 61-year-old man. His electro-cardiogram (ECG) of January in 1981 showed complete left bundle branch block (CLBBB) with normal PR interval and it then altered to complete right bundle branch block (CRBBB) with 2 : 1 atrioventricular block in April, 1982. EPS revea-led 2 : 1 His-ventricular (HV) block and a con-ducted HV interval was found to be prolonged as long as 100 msec. He was treated by pacemaker implantation. Case 2 was a 73-year-old man. His ECG showed CLBBB with prolonged PR interval of 0.25 sec in March, 1982 and it then changed to CRBBB with further prolonged PR interval of 0.28 sec in May, 1982. EPS revealed prolonged HV interval (120 msec) and alternating bundle branch block was observed during the study. A few days later, complete atrioventricular block developed and a pacemaker was implanted. Case 3 was a 87-year-old woman. Her ECG showed 2 : 1 atrioventricular block with QRS configuration of CLBBB. EPS revealed 2 : 1 HV block and a conducted HV interval was markedly prolonged as long as 120 msec.

These 3 cases of BBBB were found to have marked infrahissian conduction disturbance and the con-duction disturbance was found to be progressive. Thus, implantation of artificial pacemaker was considered to be the primary choice of treatment of these cases.