Distribution of Sympathetic Fibers in the Left Ventricular Epicardial Plexus of the Dog

Abstract

Myocardial contractile force in five areas of the left ventricle was measured in 14 dogs under chloralose anesthesia prior to and following segmental chemical epicardiectomy. Electrical stimulation of the stellate ganglia was performed before and after each segment of epicardium was destroyed, and records of myocardial contractile response to stimulation were obtained. Epicardiectomy resulted in ablation of contractile response in specific areas of the left ventricle. In a recent publication from our laboratory (Circulation Res. 22: 315, 1968), the predominance of an epicardial distribution of sympathetic fibers was demonstrated. As an extension of that work, this study demonstrates the projection of fibers from both left and right stellate ganglia and the innervation of both anterior and posterior surfaces of the left ventricle. The major projections of sympathetic fibers are oriented along an axis passing from base to apex and can be interrupted by epicardial destruction in the area of the cephalad portion of the anterior descending coronary artery and adjacent to the origin of the left marginal artery.