Right bundle branch blocks are caused by a delay in
depolarization of the right ventricle. In this case the left
ventricle is responsible for 
conducting the electrical impulse to
the right ventricle. In the event of a right bundle branch block,
three waves of depolarization occur. Conduction is not affected
to the left, therefore the normal waveforms are seen in leads V1
and V6. There is, however, an additional wave associated with
right bundle branch blocks.
Lead V1 - rSR' & R' are the result of the third wave of
depolarization traveling back toward lead V1 to depolarize the
right ventricle. If the 
complex is greater than 0.10 seconds, it
represents an incomplete right bundle branch block. If the
complex is greater than 0.12 seconds, it represents a complete
right bundle branch block.
Lead V6 - qRS & S are the result of the third wave of
depolarization traveling away from lead V6, producing a negative
deflection. If the 
complex is greater than 0.10 seconds, it
represents an incomplete right bundle branch block. If the
complex is greater than 0.12 seconds, it represents a complete
right bundle branch block.