AJP - Heart and Circulatory Physiology, Vol 251, Issue 5 920-H925, Copyright © 1986 by American Physiological Society
Common functional origin for simple and complex responses of atrioventricular node in dogs
J. Billette, J. P. Gossard, L. Lepanto and R. Cartier
The possibility that variations in atrioventricular nodal conduction time
observed during transient and steady-state nodal responses share common
characteristics was examined in six anesthetized dogs. Atrioventricular
conduction times (AV intervals) obtained during transient (incremental
atrial pacing rates, short frequency steps, and Wenckebach cycles) and
steady state (periodic premature stimulation performed at 5 basic rates)
responses were plotted together against the corresponding preceding
ventriculoatrial (VA) intervals on a graph for each dog. Despite their
diversity, nodal responses consistently resulted in AV intervals that fell
within a well-defined, relatively narrow, crescent-shaped zone on the
graphs. AV interval variations were small in the long VA interval range and
increased slightly but predictably as the VA intervals decreased. AV
intervals of transient and steady state nodal responses overlapped
markedly. These results show that AV intervals of transient and
steady-state nodal responses vary within a given common functional domain
despite the diversity of their sequential patterns and suggest that the AV
node may be obeying the same set of conduction rules during these very
distinct responses.
