Pacemaker Activity During Vagal Escape Rhythms

Abstract

In dogs, bipolar electrograms were recorded from the SA node and His bundle to localize pacemaker sites during vagal escape and to study the effects of isoproterenol on escape mechanisms. Vagal escape can result from the development of pacemaker activity above the A-V node, within the region of the A-V node, and below the common bundle of His. Isoproterenol shortened the period of asystole prior to the onset of vagal escape, increased the rate of escape rhythms at all pacemaker sites, and occasionally changed the pacemaker to a higher focus in the conduction system.