The early signs of right bundle branch block.

Complete right bundle branch block manifests with a rSR' configuration in right orientated leads and a duration of 0.12 sec or longer. Incomplete right bundle branch block is perceived as this classic rSr' configuration and a duration of less than 0.12 sec. This presentation reflects the early development of right bundle branch block which first manifests with a hitherto undescribed sign, namely: a diminution of the S wave amplitude in lead V2. Further progression of the right bundle branch block leads to slurring or notching of the upstroke of the S wave in lead V2 followed by the development of a r' deflection. With further progression, the r' deflection becomes increasingly taller until the advent of complete right bundle branch block which is characterized by a widening of a very tall R' deflection with an apical notch or plateau.