Atypical Bundle Branch Block-Report of Four Cases with Vectorcardiographic Observation

(1) Four cases with A-V block (2 of them under the age of 30) were reported and descriptions were made on the atypical QRS pattern observed when A-V conduction was restored.(2) This pattern is characterized by marked left axis deviation with right bundle branch block pattern in the precordial leads. In vectorcardio-gram, the QRS loop is on the whole, directed anteriorly and superiorly with terminal delay. The directions of inscription of the QRS loop are counterclockwise in frontal, clockwise in horizontal and counterclockwise in sagittal planes.(3) Bilateral bundle branch block was suggested for the mechanism of this pattern.