Accommodation of A-V Nodal Conduction and Fatigue Phenomenon in the His-Purkinje System

To understand the mechanisms responsible for disturbances in cardiac rhythm and conduction, it is useful to have a working knowledge of electrophysiologic events underlying normal and abnormal impulse propagation through different segments of the A-V conducting tissue. The ability to study these events in man has been facilitated by the development of the catheter technique for recording His bundle (BH) electrograms. Artificial pacing of the human heart, by permitting variations in site, rate and duration of stimulation, when used in conjunction with BH recordings have contributed significantly to the understanding of disturbances in impulse formation and conduction.