Cryoablation of the Stellate Ganglia and Atrial Arrhythmia in Ambulatory Dogs With Pacing-Induced Heart Failure

Abstract

Background: There is an association between autonomic nerve discharges and atrial arrhythmias (including bradycardia and tachycardia) in ambulatory dogs with pacing-induced heart failure (HF). Objective: The purpose of this study was to test the hypothesis that stellate ganglia ablation can reduce the incidence of atrial arrhythmias in a canine model of pacing-induced HF. Methods: Cryoablation of the caudal half of the left and right stellate ganglia and T2-T4 thoracic sympathetic ganglia was performed in six dogs (experimental group). Left upper stellate ganglia nerve activity, vagal nerve activity, and electrocardiogram were continuously recorded using an implanted radiotransmitter. Results: After 2 weeks of baseline recording, rapid right ventricular pacing (28 +/- 4 days) was used to induce HF. The control group (N = 6) underwent the same procedures except for cryoablation. The experimental group had no episodes of paroxysmal atrial tachycardia (P <.0001 vs control). Cryoablation significantly (P = .0097) reduced prolonged (>3 seconds) sinus pause episodes from 5 +/- 6 to 0 on day 1, from 250 +/- 424 to 11 +/- 11 on day 7, and from 123 +/- 206 to 30 +/- 33 on day 14 after induction of HF. In the experimental group only, vagal nerve activity may occur alone without concomitant stellate ganglia nerve activity. However, these isolated vagal nerve activity episodes did not result in prolonged sinus pause. Histologic studies confirmed successful cryoablation of the caudal half of the stellate ganglia. Conclusion: Cryoablation of bilateral stellate and T2-T4 thoracic ganglia significantly reduced paroxysmal atrial tachycardia and prolonged sinus pause episodes induced by sympathetic discharges in dogs with pacing-induced HF.