Subcutaneous nerve stimulation for rate control in ambulatory dogs with persistent atrial fibrillation

Abstract

Background: Subcutaneous nerve stimulation (ScNS) damages the stellate ganglion and improves rhythm control of atrial fibrillation (AF) in ambulatory dogs. Objective: To test the hypothesis that thoracic ScNS can improve rate control in persistent AF. Methods: We created persistent AF in 13 dogs and randomly assigned them to ScNS (N=6) and sham control groups (N=7). 18F-2-Fluoro-2-deoxyglucose (18F-FDG) positron emission tomography / magnetic resonance imaging of the brain stem was performed at baseline and at the end of the study. Results: The average stellate ganglion nerve activity (aSGNA) reduced from 4.00±1.68 μV after the induction of persistent AF to 1.72±0.42 μV (p=0.032) after ScNS. In contrast, the aSGNA increased from 3.01±1.26 μV during AF to 5.52±2.69 μV after sham stimulation (p=0.023). The mean ventricular rate during persistent AF reduced from 149±36 bpm to 84±16 bpm (p=0.011) in ScNS group but no changes were observed in control. Left ventricular ejection fraction (LVEF) remained unchanged in ScNS group but reduced significantly in sham control group. Immunostaining showed damaged ganglion cells in bilateral stellate ganglia and increased brain stem glial cell reaction in the ScNS group but not in the controls. The 18F-FDG uptake in pons and medulla was significantly (p=0.011) higher in the ScNS group than the sham control group at the end of the study. Conclusions: Thoracic ScNS causes neural remodeling in the brain stem and stellate ganglia, controls the ventricular rate and preserves the LVEF in ambulatory dogs with persistent AF.