Abstract
The vectorcardiograms of 4 cases in which left ventricular focal block coexisted with right bundle branch block were presented. In 3 cases there were initial conduction disturbances presumably due to abnormal propagation within an infarcted area (intra-infarction block). The vectorcardiographic characteristics of intrainfarction and peri-infarction block as well as their distinction from bundle branch block were emphasized. One case showed changes suggestive of intra-infarction block, but no evidence of infarction was found at necropsy. Instead there was diffuse myocardial fibrosis. The initial conduction delay was thus attributed to a nonspecific type of focal block.
It is concluded that the various types of focal block with initial vectorial abnormalities can be adequately diagnosed in the presence of right bundle branch block.
