[A method of determining the location of the pacemaker in the canine right atrium].

Theoretical calculations and experiments on hearts of open-chest dogs have demonstrated a possibility of localizing a spontaneous excitation focus by recording 2 intra-atrial delays representing differences in activation moments at 3 sites of the right atrium. Assuming myocardial homogeneity with respect to excitation spread velocity, it has been shown that the pacemaker can be localized by intersection of two hyperbola-like intra-atrial delay isochronisms with recording electrodes at their foci. In natural, i.

[Transposition of the pacemaker in the right atrium during stimulation of the vagus nerve in the dog].

The heart rate and intraatrial latencies between epicardial electrograms from three sites of the right atrium have been studied during vagal stimulation in open-chest dogs. It has been shown that alterations of latencies started at a certain cardiac cycle length irrespective of pacing frequency. A transitional process of changes from a steady latency value in the control to another steady value during vagal stimulation has been observed.