Subcutaneous nerve activity and spontaneous ventricular arrhythmias in ambulatory dogs

Abstract

Background Stellate ganglion nerve activity (SGNA) is important in ventricular arrhythmogenesis. However, because thoracotomy is needed to access the stellate ganglion, it is difficult to use SGNA for risk stratification. Objective To test the hypothesis that subcutaneous nerve activity (SCNA) in canines can be used to estimate SGNA and predict ventricular arrhythmia. Methods We implanted radio transmitters to continuously monitor left stellate ganglion and subcutaneous electrical activities in 7 ambulatory dogs with myocardial infarction, complete heart block and nerve growth factor infusion to the left stellate ganglion. Results Spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) was documented in each dog. SCNA preceded a combined 61 episodes of VT and VF, 61 frequent bigeminy or couplets and 61 premature ventricular contractions within 15 s in 70%, 59% and 61% of arrhythmias, respectively. Similar incidence of 75%, 69% and 62% was noted for SGNA. Progressive increase in SCNA (48.9 (95% CI 39.3–58.5) vs. 61.8 (95% CI 45.9–77.6) vs. 75.1 (95% CI 57.5–92.7) mV-s) and SGNA (48.6 (95% CI 40.9–56.3) vs. 58.5 (95% CI 47.5–69.4) vs. 69.0 (95% CI 53.8–84.2) mV-s) integrated over 20 s intervals was demonstrated 60 s, 40 s and 20 s prior to VT/VF (p<0.05). The Pearson’s correlation coefficient for integrated SCNA and SGNA was 0.73±0.18 (p<0.0001 for all dogs, n=5). Both SCNA and SGNA exhibited circadian variation. Conclusions SCNA can be used as an estimate of SGNA to predict susceptibility to VT and VF in a canine model of ventricular arrhythmia and sudden cardiac death.

Efficacy of Stellate Ganglion Blockade in Managing Electrical Storm

“…SGB, by mitigating catecholamine release, likely reverses the findings in a canine post-infarct model of shortened ERP in abnormal ventricular myocardium, and increased inducibility of arrhythmias in the presence of catecholamines (41). SGB may also be particularly useful for attenuating burst discharge activity in left stellate ganglion, which has been shown to precede most VT and sudden cardiac death in a canine model of ischemic cardiomyopathy (42–43). Sympathoexcitation increases repolarization heterogeneity (44–46), increases risk of delayed after depolarizations (47,48), and increases arrhythmia inducibility (49).…”

Subcutaneous nerve activity is more accurate than heart rate variability in estimating cardiac sympathetic tone in ambulatory dogs with myocardial infarction

“…8 However, Doytchinova et al recently demonstrated that SCNA can be used as a surrogate for SGNA to predict susceptibility to ventricular tachyarrhythmias in a canine model with sudden cardiac death. 7 …”

“…6 Subcutaneous inter-electrode distance was not measured at the time of the study, but in similar sized dogs it is estimated at around 28 cm. 7 After baseline recording, acute MI was created and recording continued for an additional 8 weeks.…”

“…4, 5 Recently, we demonstrated that the left thoracic subcutaneous nerve activity (SCNA) could be used to accurately estimate left stellate ganglion nerve activity (SGNA) in normal ambulatory dogs and to predict susceptibility to ventricular tachycardia (VT) and ventricular fibrillation (VF) in a canine model of ventricular arrhythmia and sudden cardiac death. 6, 7 However, whether the SCNA can be used as a marker of cardiac sympathetic tone in ambulatory dogs with MI remained unknown. In a previous study from our laboratory, Han et al simultaneously recorded left SGNA, left thoracic vagal nerve activity (VNA) and the subcutaneous electrocardiogram (ECG) in 9 ambulatory dogs at baseline and after MI.…”

Neuromodulation for cardiac arrhythmia

“…The role of sympathetic hyperactivity outside the heart in arrhythmogenesis has also been reported by Huang et al [30] that electrical stimulation of the left renal sympathetic nerves induced both systemic and cardiac sympathetic hyperactivity and increases the incidence of ischemia-induced VT/VF. In another study, continuous recording of the LSG activity in ambulatory dogs after myocardial infarction (MI) demonstrated that increased LSG and subcutaneous nerve activity preceded the episodes of premature ventricular contractions and VT/VF [31] .These studies strongly indicate that sympathetic hyperactivity and heterogeneous sympathetic nerve sprouting or hyperinnervation are tightly associated with the occurrence of VT/VF.…”