Abstract 036: The Role Of Spinal Modulation On The Ventricular Electrophysiology In A Porcine Model

Abstract

Background: Enhanced cardiac sympathetic tone has been associated with ventricular arrhythmias and sudden cardiac death. The spinal cord is an important integrative region of afferent and efferent pathways that participate in cardiovascular regulation. The purpose of this study is to investigate the role of spinal processing of cardiac afferent information on ventricular electrophysiology during cardiac sympathoexcitation. Methods: Female Yorkshire pigs (n=5) underwent surgical exposure of the heart and left stellate ganglion (LSG) through thoractomy as well as the dorsal and ventral roots of the spinal cord through laminectomy. A 56-electrode sock was placed over the ventricles to record epicardial electrograms. Animals underwent LSG stimulation in intact, after dorsal root transaction (DRTx), and followed by ventral root transaction (DVRTx). Activation recovery intervals (ARIs) were measured at each electrode before and during LSG stimulation. Results: With intact roots LSG stimulation resulted in significant global ARI shortening by 12.9% (p<0.05). After DRTx, mean global ARI shortened by 7.2%. LSG stimulation after DRTx and DVRTx resulted in greater ARI shortening compared to LSG stimulation with intact roots (21.5 and 18.4 vs 12.9%, p<0.05, see figure 1 below). ARI shortened more during LSG stimulation after DRTx than that after DVRTx (21.5 vs. 18.4%, p<0.05). Conclusion: Spinal afferent pathways play an inhibitory role in sympathoexcitation of ventricle induced by LSG stimulation. This finding provides insight into the mechanism underlying the beneficial effects of thoracic epidural anesthesia in reducing ventricular arrhythmias.