Left ventricular dynamics in complete right bundle-branch block with left axis deviation of QRS.

SUMMARY The time intervals defined by the simultaneous recording of an electrocardiogram, phonocardiogram, indirect carotid pulse curve, and apexcardiogram made it possible to compare the left ventricular (LV) dynamics in a group of 33 cases of complete right bundle-branch block with left axis deviation (RBBB-LAD) with two control groups, one consisting of 30 cases of complete right bundle-branch block without left axis deviation (RBBB without LAD) and the other of 30 cases of left axis deviation (LAD) alone. The LV dynamics of RBBB-LAD differed from those of both control groups of RBBB without LAD and of LAD alone by a significantly late onset of LV ejection in the former, resulting from both late onset and slow rise of LV contraction. On the other hand, the delayed LV activity was not significantly different between the group of RBBB-LAD and a previously studied group of complete left bundle-branch block. Normal limits for these intervals were looked for to make it possible to diagnose a late LV activity in the individual patient, and so provide a further argument in the discussion for an eventual cardiac pacing in doubtful cases. Finally, it was not felt possible to use these intervals to try to localize the site of the conduction disturbance, whether in the bundle branch or in the ventricular wall itself.