Abstract 14231: Electrophysiological and Mechanical Effects of Endocardial Vagal Atrio-Ventricular Node Inhibition
Background: Previous studies have demonstrated that AV-nodal stimulation (AVNS) can be used for rhythm control during atrial fibrillation. We investigated the electrical and mechanical consequences of AVNS in order to improve clinical applicability.
Methods: Experiments were performed on 7 goats. A bipolar lead was placed in the right atrial septal area for AVNS. The intervention consisted of delivery of constant voltage (1–10V), 50Hz bursts during the atrial refractory period (designated AVNSAREF). An additional catheter was placed in the atria for both pacing and sensing. A dual sensor Millar pressure catheter was used to measure left ventricular and aortic pressures.
Results: The PQ-prolongation by AVNSAREF increased with increasing voltage and was dependent on the atrial activation cycle length (see figure). AVNSAREF only prolonged the refractory period (RP) of the AV-node (from 234±71 to 298±68ms) but did not significantly affect the RP of either the atria (from 143±24 to 136±27ms), HIS (from 255±14 to 262±19ms) or right ventricle (from 245±12 to 243±18ms). In addition, the time-differences (measured by strips of epicardial electrodes) in local activation (36±7 ms) and repolarization (62±15 ms) of the left ventricle were not changed by AVNSAREF (37±7 and 51±14 ms, respectively). Hemodynamic evaluation revealed a small but significant negative change by AVNSAREF in left ventricular contractility (−117 ±104 mm Hg/sec; ∼5% decrease) and left ventricular systolic pressure (−2.1±1.6 mmHg; ∼2% decrease). All effects of AVNSAREF were blocked by administration by atropine.
Conclusions: AVNSAREF specifically activates the parasympathetic nerves innervating the AV-node. Due to the highly specific electrophysiological outcomes of AVNS, it may be used for ventricular rate stabilization during atrial arrhythmias.
- © 2010 by American Heart Association, Inc.