New technique for vagal nerve stimulation

Introduction: The vagus nerve travels in a neurovascular bundle with the ca rotid artery and internal jugular vein. The present study was designed to a ssess whether transvascular stimulation through the carotid artery of the d og can be used to directly stimulate the vagus nerve and increase parasympa thetic tone. Methods: In five anesthetized dogs, a steerable electrode cath eter was positioned under fluoroscopic guidance in the right carotid artery in the mid neck via the femoral artery. Multipolar catheters were position ed transvenously through the femoral vein in the right atrium, across the t ricuspid valve to record a His-bundle electrogram, and in the right ventric le. Results: In all five animals, vagal nerve stimulation was successfully achieved with outputs ranging between 10 and 30 mA. Sinus cycle length incr eased from 473 +/- 113 ms at baseline to 894 +/- 315 ms (P < 0.025) during stimulation from the right carotid artery. There was an increase in the AH interval from 55 +/- 14 to 71 +/- 23 ms (P < 0.03), a shortening of the atr ial effective refractory period from 136 +/- 8 to 126 +/- 6 ms (P < 0.01), and a fall in the systolic blood pressure from 135 +/- 20 to 117 +/- 20 mmH g (P < 0.005) with stimulation from the right carotid artery. A prolongatio n of the AV and VA block cycle lengths and the AV nodal effective refractor y period was also noted with stimulation from the right carotid artery. Atr ial fibrillation was not induced at baseline in any animal. During stimulat ion from the right carotid artery, atrial fibrillation was induced in three of five animals and persisted for the duration of stimulation from the rig ht carotid artery. Conclusion: Cardiac parasympathetic stimulation can be a chieved by positioning a catheter in the neurovascular bundle in the neck a djacent to the vagus nerve with resultant effects on cardiac electrophysiol ogy. (C) 1999 Published by Elsevier Science B.V. All rights reserved.