Yu L, Wang S, Zhou X, Wang Z, Huang B, Liao K, Saren G, Chen M, Po SS, Jiang H. Chronic Intermittent Low-Level Stimulation of Tragus Reduces Cardiac Autonomic Remodeling and Ventricular Arrhythmia Inducibility in a Post-Infarction Canine Model.
JACC Clin Electrophysiol 2015;
2:330-339. [PMID:
29766893 DOI:
10.1016/j.jacep.2015.11.006]
[Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 10/27/2015] [Accepted: 11/26/2015] [Indexed: 11/24/2022]
Abstract
OBJECTIVES
This study investigated whether chronic low-level tragus stimulation (LL-TS) inhibits cardiac sympathetic remodeling and reduces ventricular arrhythmia inducibility in a post-infarction canine model.
BACKGROUND
Low-level vagal stimulation has been shown to suppress cardiac sympathetic activity, which plays an important role in ventricular arrhythmia after myocardial infarction (MI). Our previous studies reported a noninvasive approach to deliver vagal stimulation by transcutaneous stimulation at the tragus, where the auricular branch of the vagus nerve is located.
METHODS
Twenty-two beagles were randomized to the normal control (n = 6), MI (left anterior descending coronary artery ligation without LL-TS [n = 8]), and TS (MI plus LL-TS [n = 8]) groups. LL-TS was delivered 2 h each day at 80% below the threshold which slowed sinus rate.
RESULTS
At 2-month follow-up, LL-TS was found to significantly reduce ventricular arrhythmia inducibility (arrhythmia score: 1.8 ± 0.8 vs. 3.6 ± 0.7, p < 0.01, compared to the MI group), decreased left stellate ganglion (LSG) activity (frequency: 32 ± 15 vs. 112 ± 29 impulses/s; and amplitude: 0.15 ± 0.12 mV vs. 0.38 ± 0.12 mV, compared to MI group), and attenuated cardiac sympathetic remodeling induced by chronic MI. The nerve growth factor (NGF) protein was down-regulated, whereas the small conductance calcium-activated potassium channel type2 (SK2) protein was up-regulated in the LSG by chronic LL-TS.
CONCLUSIONS
Chronic LL-TS could reduce the ventricular arrhythmia inducibility, LSG neural activity and sympathetic neural remodeling in a post-infarction canine model. Down-regulation of NGF protein and up-regulation of SK2 protein in the LSG contribute to the salutary effects of LL-TS.
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