Browsing by Subject "Vagus nerve"

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    Effects of Stellate Ganglion Cryoablation on Subcutaneous Nerve Activity and Atrial Tachyarrhythmias in a Canine Model of Pacing-Induced Heart Failure
    (Elsevier, 2018-05) Shelton, Richard S.; Ogawa, Masahiro; Lin, Hongbo; Shen, Changyu; Wong, Johnson; Lin, Shien-Fong; Chen, Peng-Sheng; Everett, Thomas H.; Medicine, School of Medicine
    OBJECTIVES: This study aimed to test the hypothesis that subcutaneous nerve activity (SCNA) can adequately estimate the cardiac sympathetic tone and the effects of cryoablation of the stellate ganglion in dogs with pacing-induced heart failure (HF). BACKGROUND: Recording of SCNA is a new method to estimate sympathetic tone in dogs. HF is known to increase sympathetic tone and atrial arrhythmias. METHODS: Twelve dogs with pacing-induced HF were studied using implanted radiotransmitters to record the stellate ganglia nerve activity (SGNA), vagal nerve activity, and SCNA. Of these, 6 dogs (ablation group) underwent bilateral stellate ganglia cryoablation before the rapid ventricular pacing; the remaining 6 dogs (control group) had rapid ventricular pacing only. In both groups, SCNA was compared with SGNA and the occurrence of arrhythmias. RESULTS: SCNA invariably increased before the 360 identified atrial tachyarrhythmia episodes in the 6 control dogs before and after HF induction. SCNA and SGNA correlated in all dogs with an average correlation coefficient of 0.64 (95% confidence interval: 0.58 to 0.70). Cryoablation of bilateral stellate ganglia significantly reduced SCNA from 0.34 ± 0.033 μV to 0.25 ± 0.028 μV (p = 0.03) and eliminated all atrial tachyarrhythmias. CONCLUSIONS: SCNA can be used to estimate cardiac sympathetic tone in dogs with pacing-induced HF. Cryoablation of the stellate ganglia reduced SCNA and arrhythmia vulnerability.
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    An emerging method to noninvasively measure and identify vagal response markers to enable bioelectronic control of gastroparesis symptoms with gastric electrical stimulation
    (Elsevier, 2020-04-15) Ward, Matthew P.; Gupta, Anita; Wo, John M.; Rajwa, Bartek; Furness, John B.; Powley, Terry L.; Nowak, Thomas V.; Medicine, School of Medicine
    Background: Gastric electrical stimulation (GES) can be a life-changing, device-based treatment option for drug-resistant nausea and vomiting associated with diabetic or idiopathic gastroparesis (GP). Despite over two decades of clinical use, the mechanism of action remains unclear. We hypothesize a vagal mechanism. New method: Here, we describe a noninvasive method to investigate vagal nerve involvement in GES therapy in 66 human subjects through the compound nerve action potential (CNAP). Results: Of the 66 subjects, 28 had diabetic GP, 35 had idiopathic GP, and 3 had postsurgical GP. Stimulus charge per pulse did not predict treatment efficacy, but did predict a significant increase in total symptom score in type 1 diabetics as GES stimulus charge per pulse increased (p < 0.01), representing a notable side effect and providing a method to identify it. In contrast, the number of significant left and right vagal fiber responses that were recorded directly related to patient symptom improvement. Increased vagal responses correlated with significant decreases in total symptom score (p < 0.05). Comparison with existing method(s): We have developed transcutaneous recording of cervical vagal activity that is synchronized with GES in conscious human subjects, along with methods of discriminating the activity of different nerve fiber groups with respect to conduction speed and treatment response. Conclusions: Cutaneous vagal CNAP analysis is a useful technique to unmask relationships among GES parameters, vagal recruitment, efficacy and side-effect management. Our results suggest that CNAP-guided GES optimization will provide the most benefit to patients with idiopathic and type 1 diabetic gastroparesis.