Horwitz S, Lupi E, Hayes J, Frishman W, Cárdenas M, Killip T
Chest. 1975 Sep;68(3):317-20. doi: 10.1378/chest.68.3.317.
The two current criteria for diagnosis of left anterior fascicular block (LAFB) were evaluated; they are marked left axis deviation (LAD) and a delay in the time of inscription of the intrinsicoid deflection (ID) in lead aVL asynchronous to V6. From 400 electrocardiograms with a LAD of --30 degrees or greater, 62 percent showed asynchronous activation of the left ventricle. There was only a general relationship between the degree of LAD and delayed ID in aVL. The incidence of delayed ID in aVL was as follows: 2 percent with mean frontal QRS axis at 0 degrees; 9 percent at --15 degrees; 41 percent at --30 degrees; 69 percent at --45 degrees; 82 percent at --60 degrees; and 100 percent at --75 degrees or greater. The lack of correlation between both criteria in many instances questions their validity. The LAD alone should not be considered synonymous with LAFB. Recognition of delayed inscription of the ID in aVL is a useful supplemental criterion for diagnosis.
对目前用于诊断左前分支阻滞（LAFB）的两个标准进行了评估；这两个标准是显著的左轴偏移（LAD）以及aVL导联中本征性QRS波终末向量（ID）的记录时间延迟且与V6导联不同步。在400份LAD为-30度或更大的心电图中，62%显示左心室激活不同步。LAD程度与aVL导联中ID延迟之间仅存在一般关系。aVL导联中ID延迟的发生率如下：平均额面QRS轴为0度时为2%；-15度时为9%；-30度时为41%；-45度时为69%；-60度时为82%；-75度或更大时为100%。在许多情况下，这两个标准之间缺乏相关性，这对它们的有效性提出了质疑。不应仅将LAD视为LAFB的同义词。认识到aVL导联中ID记录延迟是诊断的一个有用补充标准。
