Stochastic vagus nerve stimulation affects acute heart rate dynamics in rats

Abstract

Vagus nerve stimulation (VNS) is an approved therapy for treatment of epilepsy and depression. While also shown to be promising in several preclinical and clinical studies to treat cardiovascular diseases, optimal therapeutic stimulation paradigms are still under investigation. Traditionally, parameters such as frequency, current, and duty cycle are used to adjust the efficacy of VNS therapy. This study explored the effect of novel stochastic VNS (S-VNS) on acute heart rate (HR) dynamics. The effect of S-VNS was evaluated in Sprague Dawley rats by comparing the acute HR and HR variability (HRV) responses to standard, periodic VNS (P-VNS) across different frequencies (FREQs, 10–30 Hz). Our results demonstrate that both S-VNS and P-VNS produced negative chronotropic effects in a FREQ-dependent manner with S-VNS inducing a significantly smaller drop in HR at 10 Hz and 20 Hz compared to P-VNS (p<0.05). S-VNS demonstrated a FREQ-dependent drop in the SD1/SD2 ratio, a measure of HRV, which was absent in P-VNS, suggesting that S-VNS may acutely modulate the nonlinear relationship between short- and long-term HRV. In conclusion, S-VNS is a novel stimulation procedure that may provide different physiological outcomes from standard P-VNS, as indicated by our analysis of HR dynamics. Our study provides a rationale for further detailed investigations into the therapeutic potential of S-VNS as a novel neuromodulation technique.

Anodal block permits directional vagus nerve stimulation

“…On the other hand, afferent vagal, A-type and C-type, sensory fibers innervate lung stretch receptors and nociceptors, respectively, and, when stimulated, elicit various changes in breathing rate and pattern 30,45 . Similar changes in cardiac and pulmonary functional parameters in response to cervical VNS have been reported in experimental animals 27,46 and in humans 47 , but this is the first time, to our knowledge, that these responses have been evaluated in the context of vagotomies, providing direct functional evidence for 2 easily obtainable, in experimental animals and in humans, markers of activation by VNS of efferent and afferent vagal fibers, respectively 47 .…”

Electric vagal nerve stimulation inhibits inflammation and improves postoperation cognitive dysfunction in aged rats

“…As to why right vagal nerve was stimulated in our study, this was because heart rate changed obviously when it was stimulated [13]. In other words, the change of heart rate is not only the evidence that the stimulation is successful, but also is the baseline to regulate the parameter of stimulation, such as the stimulation intensity and frequency.…”

“…Because right vagal nerve primarily innervates the atria and the sinoatrial node, and the stimulation may induce significant change in cardiac rhythm. At the same time, right VNS produce smaller cardiorespiratory response, so the right vagal nerve was applied [13,14]. Isolating the right cervical vagal nerve and common carotid artery bundle, a 1.5mm diameter silver bipolar cuff electrode was gently wrapped around the nerve bundle and fixed to the sternocleidomastoid muscle.…”

Electric vagal nerve stimulation inhibits inflammation and improves early postoperation cognitive dysfunction in aged rats

“…Because right vagal nerve primarily innervates atria and sinoatrial node, and these stimulation may induce significant change in cardiac rhythm. At the same time, right VNS produce smaller cardiorespiratory response, so right vagal nerve was applied [13,14]. Isolating right cervical vagal nerve and common carotid artery bundle, a 1.5mm diameter silver bipolar cuff electrode was gently wrapped around the nerve bundle and fixed to the sternocleidomastoid muscle.…”