Dromotropic Effects of Stellate Stimulation on the AV Node and Internodal Pathways 1

Abstract

Summary

The dromotropic effects of supramaximal stimulation of the right (RSS) and left (LSS) stellate ganglia on segments of the middle (MIN) and posterior (PIN) internodal pathways of James and across the AV node were studied in the anesthetized, open chest dog maintained on cardiopulmonary bypass. Contiguous bipolar electrodes were sutured over the sinus node and on the lateral surface of the right atrial appendage for pacing, and at three points along the MIN and PIN for measuring conduction time. One electrode was placed over the crista terminalis at the caudal pole of the SA node; a second across the crista at the level of the limbus of the fossa ovalis; and a third bipolar electrode over the PIN as it courses between the coronary sinus and AV ring. Conduction time through the AV node was assessed by alterations in the a-h sub-interval of the His electrogram which was recorded with a Hoffman-type electrode sutured over the His bundle. With pacing from either the sinus node or lateral surface of the right atrial appendage at rates sufficient to maintain capture, no significant change in conduction time along segments of the MIN or PIN were observed during either RSS or LSS, or following injections of 0.5 μg/kg NE. Significant differences in the effects of RSS and LSS on conduction through the AV node were noted. Expressed in terms of percentage change from the control a-h subinterval, LSS shortened this interval 27% while RSS shortened it by only 17% (p < 0.001). However, there was no significant dromotropic influence of either right or left stellate ganglion stimulation on the h-v subinterval.