冠攣縮時における心室性不整脈のQRS波形に関する検討

Studies of configuration of QRS wave of ventricular arrhythmia in coronary spasm

　急性心筋虚血時には，しばしば重篤な心室性不整脈が出現し，突然死の原因となる場合が多いと考えられている。ergonovine誘発冠動脈攣縮^1）時に，心室性期外収縮（VPB），発作性心室頻拍（VT），心室細動（Vf）などの心室性不整脈が高頻度に出現することも報告されている^2〜4）。このergonovine maleate （EM）による冠攣縮時の狭心症およびST変化は、異型狭心症の自然発作時のそれらに類似し^5），急性心筋梗塞の初期変化に似た心電図所見を示す。

　本研究においては，vasospastic anginaが疑われる例にEMを負荷して冠攣縮を誘発し，急性心筋虚血時の心室性不整脈，ことにVPB波形の多様性およびVTへの移行について検討を加えた。

The features of ventricular arrhythmia in coro-nary spasm induced by ergonovine were examined in order to elucidate the characteristics of ventricu-lar arrhythmia in acute myocardial ischemia.

One important finding in our study was that the coupling intervals and configurations of QRS wave of the ventricular premature beats (VPBs) varied very much even in the same case and in the same time phase.

Prematurity index (R-R'/QR) of VPBs with right bundle branch block (RBBB) pattern was significantly smaller than that of the left bundle branch block (LBBB) pattern. Vulnerability index (R-R×QT/R-R') of VPBs with RBBB pattern was significantly larger than that of the LBBB pattern. Incidence of VPBs with RBBB pattern (50.9%) was slightly larger than that of the LBBB pattern (40.5 %). VPBs with RBBB pattern developed to ventri-cular tachycardias (VTs) in 29 out of 117 cases (24.8%) and VPBs with LBBB pattern developed to VTs in 11 out of 94 cases (11.7%). So it was considered that the VPBs with RBBB pattern more easily developed to VTs than those with LBBB pattern. But it is difficult to assess the clinical signi-ficance of VPBs from their QRS morphology alone, because 11 out of 40 VTs (27.5%) were initiated by VPBs with LBBB pattern.