Non-invasive Low-level Tragus Stimulation in Cardiovascular Diseases.
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ABSTRACT:
SUBMITTER: Jiang Y
PROVIDER: S-EPMC7330730 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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Project description:BackgroundRecent studies have demonstrated that antiadrenergic autoantibodies are involved in the pathophysiology of postural orthostatic tachycardia syndrome (POTS).ObjectiveThe purpose of this study was to test the hypothesis that transcutaneous low-level tragus stimulation (LLTS) ameliorates autoantibody-induced autonomic dysfunction and inflammation in a rabbit model of autoimmune POTS.MethodsSix New Zealand white rabbits were co-immunized with peptides from the α1-adrenergic and β1-adrenergic receptors to produce sympathomimetic antibodies. The tilt test was performed on conscious rabbits before immunization, 6 weeks after immunization, and 10 weeks after immunization with 4-week daily LLTS treatment. Each rabbit served as its own control.ResultsAn enhanced postural heart rate increase in the absence of significant change in blood pressure was observed in immunized rabbits, confirming our previous report. Power spectral analysis of heart rate variability during the tilt test showed a predominance of sympathetic over parasympathetic activity in immunized rabbits as reflected by markedly increased low-frequency power, decreased high-frequency power, and increased low-to-high-frequency ratio. Serum inflammatory cytokines were also significantly increased in immunized rabbits. LLTS suppressed the postural tachycardia, improved the sympathovagal balance with increased acetylcholine secretion, and attenuated the inflammatory cytokine expression. Antibody production and activity were confirmed with in vitro assays, and no antibody suppression by LLTS was found in this short-term study.ConclusionLLTS improves cardiac autonomic imbalance and inflammation in a rabbit model of autoantibody-induced hyperadrenergic POTS, suggesting that LLTS may be used as a novel neuromodulation therapy for POTS.
| S-EPMC9975011 | biostudies-literature
Project description:Background Low-level tragus stimulation (LLTS) has been shown to significantly reduce atrial fibrillation (AF) burden in patients with paroxysmal AF. P-wave alternans (PWA) is believed to be generated by the same substrate responsible for AF. Hence, PWA may serve as a marker in guiding LLTS therapy. We investigated the utility of PWA in guiding LLTS therapy in patients with AF. Methods and Results Twenty-eight patients with AF were randomized to either active LLTS or sham (earlobe stimulation). LLTS was delivered through a transcutaneous electrical nerve stimulation device (pulse width 200 μs, frequency 20 Hz, amplitude 10-50 mA), for 1 hour daily over a 6-month period. AF burden over 2-week periods was assessed by noninvasive continuous ECG monitoring at baseline, 3 months, and 6 months. A 5-minute control ECG for PWA analysis was recorded during all 3 follow-up visits. Following the control ECG, an additional 5-minute ECG was recorded during active LLTS in all patients. At baseline, acute LLTS led to a significant rise in PWA burden. However, active patients receiving chronic LLTS demonstrated a significant reduction in both PWA and AF burden after 6 months (P<0.05). Active patients who demonstrated an increase in PWA burden with acute LLTS showed a significant drop in AF burden after 6 months of chronic LLTS. Conclusions Chronic, intermittent LLTS resulted in lower PWA and AF burden than did sham control stimulation. Our results support the use of PWA as a potential marker for guiding LLTS treatment of paroxysmal AF.
| S-EPMC8477868 | biostudies-literature
Project description:BackgroundAutonomic dysregulation in heart failure with reduced ejection fraction plays a major role in endothelial dysfunction. Low-level tragus stimulation (LLTS) is a novel, noninvasive method of autonomic modulation.Methods and resultsWe enrolled 50 patients with heart failure with reduced ejection fraction (left ventricular ejection fraction of ≤40%) in a randomized, double-blinded, crossover study. On day 1, patients underwent 60 minutes of LLTS with a transcutaneous stimulator (20 Hz, 200 μs pulse width) or sham (ear lobule) stimulation. Macrovascular function was assessed using flow-mediated dilatation in the brachial artery and cutaneous microcirculation with laser speckle contrast imaging in the hand and nail bed. On day 2, patients were crossed over to the other study arm and underwent sham or LLTS; vascular tests were repeated before and after stimulation. Compared with the sham, LLTS improved flow-mediated dilatation by increasing the percent change in the brachial artery diameter (from 5.0 to 7.5, LLTS on day 1, P = .02; and from 4.9 to 7.1, LLTS on day 2, P = .003), compared with no significant change in the sham group (from 4.6 to 4.7, P = .84 on day 1; and from 5.6 to 5.9 on day 2, P = .65). Cutaneous microcirculation in the hand showed no improvement and perfusion of the nail bed showed a trend toward improvement.ConclusionsOur study demonstrated the beneficial effects of acute neuromodulation on macrovascular function. Larger studies to validate these findings and understand mechanistic links are warranted.
| S-EPMC9473302 | biostudies-literature
Project description:Aims: Microvolt T-wave alternans (TWA), an oscillation in T-wave morphology of the electrocardiogram (ECG), has been associated with increased susceptibility to ventricular tachy-arrhythmias, while vagus nerve stimulation has shown promising anti-arrhythmic effects in in vivo and ex vivo animal studies. We aimed to examine the effect of non-invasive, acute low-level tragus stimulation (LLTS) on TWA in patients with ischemic cardiomyopathy and heart failure. Methods: 26 patients with ischemic cardiomyopathy (left ventricular ejection fraction <35%) and chronic stable heart failure, previously implanted with an automatic implantable cardioverter defibrillator (ICD) device with an atrial lead (dual chamber ICD or cardiac resynchronization therapy defibrillator), were enrolled in the study. Each patient sequentially received, (1) Sham LLTS (electrode on tragus, but no stimulation delivered) for 5 min; (2) Active LLTS at two different frequencies (5 and 20 Hz, 15 min each); and (3) Active LLTS, during concomitant atrial pacing at 100 bpm at two different frequencies (5 and 20 Hz, 15 min each). LLTS was delivered through a transcutaneous electrical nerve stimulation device (pulse width 200 μs, frequency 5/20 Hz, amplitude 1 mA lower than the discomfort threshold). TWA burden was assessed using continuous ECG monitoring during sham and active LLTS in sinus rhythm, as well as during atrial pacing. Results: Right atrial pacing at 100 bpm led to significantly heightened TWA burden compared to sinus rhythm, with or without LLTS. Acute LLTS at both 5 and 20 Hz, during sinus rhythm led to a significant rise in TWA burden in the precordial leads (p < 0.05). Conclusion: Acute LLTS results in a heart-rate dependent increase in TWA burden.
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Project description:Background: Sepsis can lead to multiple organ damage, and the heart is one of the most vulnerable organs. Vagal nerve stimulation can reduce myocardial injury in sepsis and improve survival rate. However, the relative effect of disparate cell populations on sepsis induced myocardial dysfunction and the low-level tragus stimulation on it, remain unclear. Methods: We used the cardiac single-cell transcriptomic strategy to characterize the cardiac cell population and the network of cells that forms the heart. And we selected all cardiac macrophage from CD45+ cells using single-cell mRNA sequencing data. Then we used echocardiography performing, western blot and immunofluorescence and immunohistochemical technology to verify the data of the single-cell mRNA sequencing results. Results: In single-cell mRNA sequencing data, our analysis provides a comprehensive map of the cardiac cellular landscape uncovering multiple cell populations that contribute to sepsis induced myocardial dysfunction under low-level tragus stimulation. Pseudo timing analysis in single-cell sequencing showed that low level vagal nerve stimulation could induce the transformation of cardiac monocytes into M2 macrophages and play an anti-inflammatory role. After low-level tragus stimulation, the expression of α7nAChR in the heart tissue increased significantly. Echocardiography showed that low-level tragus stimulation could improve the cardiac function of septic myocardial injury of the mice. Comparing with the sepsis group, the expression of interleukin-1β in heart tissue of the mice in sepsis with low-level tragus stimulation group is significantly lower. Conclusion: Low-level tragus stimulation can improve sepsis-induced myocardial dysfunction by promoting cardiac monocytes to M2 macrophages. Goal of the study: In the present study, we aimed to screen macrophages, their crosstalk with other cells, and macrophages associated with cardiac injury and further verify their origins and roles in the septic myocardial injury process and low-level tragus stimulation (LL-TS) to treat septic myocardial dysfunction.
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Project description:Accumulating evidence suggests that non-invasive and invasive brain stimulation may reduce food craving and calorie consumption rendering these techniques potential treatment options for obesity. Non-invasive transcranial direct current stimulation (tDCS) or repetitive transcranial magnet stimulation (rTMS) are used to modulate activity in superficially located executive control regions, such as the dorsolateral prefrontal cortex (DLPFC). Modulation of the DLPFC's activity may alter executive functioning and food reward processing in interconnected dopamine-rich regions such as the striatum or orbitofrontal cortex. Modulation of reward processing can also be achieved by invasive deep brain stimulation (DBS) targeting the nucleus accumbens. Another target for DBS is the lateral hypothalamic area potentially leading to improved energy expenditure. To date, available evidence is, however, restricted to few exceptional cases of morbid obesity. The vagal nerve plays a crucial role in signaling the homeostatic demand to the brain. Invasive or non-invasive vagal nerve stimulation (VNS) is thus assumed to reduce appetite, rendering VNS another possible treatment option for obesity. Based on currently available evidence, the U.S. Food and Drug Administration recently approved VNS for the treatment of obesity. This review summarizes scientific evidence regarding these techniques' efficacy in modulating food craving and calorie intake. It is time for large controlled clinical trials that are necessary to translate currently available research discoveries into patient care.
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Project description:People generally have imperfect introspective access to the mechanisms underlying their political beliefs, yet can confidently communicate the reasoning that goes into their decision making process. An innate desire for certainty and security in ones beliefs may play an important and somewhat automatic role in motivating the maintenance or rejection of partisan support. The aim of the current study was to clarify the role of the DLPFC in the alteration of political beliefs. Recent neuroimaging studies have focused on the association between the DLPFC (a region involved in the regulation of cognitive conflict and error feedback processing) and reduced affiliation with opposing political candidates. As such, this study used a method of non-invasive brain simulation (tRNS) to enhance activity of the bilateral DLPFC during the incorporation of political campaign information. These findings indicate a crucial role for this region in political belief formation. However, enhanced activation of DLPFC does not necessarily result in the specific rejection of political beliefs. In contrast to the hypothesis the results appear to indicate a significant increase in conservative values regardless of participant's initial political orientation and the political campaign advertisement they were exposed to.
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