Abstract Background Transcutaneous low-level tragus electrical stimulation (LLTS) suppresses atrial fibrillation (AF) in canines. Objectives This study examined the antiarrhythmic and ...anti-inflammatory effects of LLTS in humans. Methods Patients with paroxysmal AF who presented for AF ablation were randomized to either 1 h of LLTS (n = 20) or sham control (n = 20). Attaching a flat metal clip onto the tragus produced LLTS (20 Hz) in the right ear (50% lower than the voltage slowing the sinus rate). Under general anesthesia, AF was induced by burst atrial pacing at baseline and after 1 h of LLTS or sham treatment. Blood samples from the coronary sinus and the femoral vein were collected at those time points and then analyzed for inflammatory cytokines, including tumor necrosis factor alpha and C-reactive protein, using a multiplex immunoassay. Results There were no differences in baseline characteristics between the 2 groups. Pacing-induced AF duration decreased significantly by 6.3 ± 1.9 min compared with baseline in the LLTS group, but not in the control subjects (p = 0.002 for comparison between groups). AF cycle length increased significantly from baseline by 28.8 ± 6.5 ms in the LLTS group, but not in control subjects (p = 0.0002 for comparison between groups). Systemic (femoral vein) but not coronary sinus tumor necrosis factor (TNF)-alpha and C-reactive protein levels decreased significantly only in the LLTS group. Conclusions LLTS suppresses AF and decreases inflammatory cytokines in patients with paroxysmal AF. Our results support the emerging paradigm of neuromodulation to treat AF.
Mitigation of cardiac autonomic dysregulation by neuromodulation technologies is emerging as a new therapeutic modality of heart failure (HF). This recent progress has necessitated the identification ...of a biomarker for the quantification of sympathovagal balance, the potential target of ‘neuromodulation’ strategies. The currently available autonomic nervous system assessment parameters do not truly reflect the sympathovagal balance of the ventricle. Protein kinase A (PKA) is an intracellular enzyme that plays a major role in the pathophysiology of functional and structural ventricular remodeling in HF. Interestingly, sympathetic and parasympathetic activations exert reciprocal influence on the activity of PKA. The current review attempts to evaluate the potential concept and feasibility of using in vitro assessment of PKA activity as a marker of sympathovagal balance in HF.
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Post-operative atrial fibrillation (POAF) is associated with worse long-term cardiovascular outcomes.
This study hypothesized that injecting calcium chloride (CaCl
) into the major atrial ...ganglionated plexi (GPs) during isolated coronary artery bypass grafting (CABG) can reduce the incidence of POAF by calcium-induced autonomic neurotoxicity.
This proof-of-concept study randomized 200 patients undergoing isolated, off-pump CABG to CaCl
(n = 100) or sodium chloride (sham, n = 100) injection. Two milliliters of CaCl
(5%) or sodium chloride (0.9%) was injected into the 4 major atrial GPs during CABG. All patients received 7-day continuous telemetry and Holter monitoring. The primary outcome was incidence of POAF (≥30 s) in 7 days. Secondary outcomes included length of hospitalization, POAF burden, average ventricular rate during AF, plasma level of inflammatory markers, and actionable antiarrhythmic therapy to treat POAF.
The POAF incidence was reduced from 36% to 15% (hazard ratio: 0.366; 95% confidence interval: 0.211 to 0.635; p = 0.001). Length of hospitalization did not differ between the 2 groups. POAF burden (first 7 post-operative days), the use of amiodarone or esmolol, and the incidence of atrial couplets and nonsustained atrial tachyarrhythmias were significantly reduced in the CaCl
group. Heart rate variability data showed a decrease in both high-frequency and low-frequency power in the CaCl
group with a preserved low-frequency/high-frequency ratio, suggesting that the sympathetic/parasympathetic balance was not perturbed by CaCl
injection.
Injection of CaCl
into the 4 major atrial GPs reduced the POAF hazard by 63%. Inhibition of GP function by Ca-mediated neurotoxicity may underlie the therapeutic effect. (Calcium Autonomic Denervation Prevents Postoperative Atrial Fibrillation; ChiCTR1800019276).
Studies have shown that left stellate ganglion (LSG) suppression protects against ventricular arrhythmias (VAs). Optogenetics is a novel technique to reversibly regulate the activity of the targeted ...neurons.
This study aimed to investigate whether an optogenetically silenced LSG could protect against VAs induced by myocardial ischemia.
Adeno-associated virus (AAV) was used as the vector to deliver ArchT, an inhibitory light-sensitive opsin, to the LSG neurons. Twenty male beagles were randomized into the optogenetics group (n = 10, AAV2/9-CAG-ArchT-GFP microinjected into LSG) and control group (n = 10, AAV2/9-CAG-GFP microinjected into LSG). After 4 weeks, the LSG function and neural activity, heart rate variability, ventricular action potential duration, and effective refractory period were measured in the absence or presence of a light-emitting diode illumination (565 nm). Myocardial ischemia was induced by left anterior coronary artery ligation and 1 h of electrocardiography was recorded for VAs analysis.
ArchT was successfully expressed in all dogs. Transient light-emitting diode illumination significantly suppressed the LSG function, LSG neural activity, and sympathetic nerve indices of heart rate variability as well as prolonged left ventricular effective refractory period and APD90 only in the optogenetics group. Thirty-minute illumination further enhanced these changes in the optogenetics group. Importantly, all of these changes returned to baseline within 2 h after illumination was turned off. Moreover, the ischemia-induced VAs were significantly suppressed by illumination only in the optogenetics group.
Optogenetic modulation could reversibly inhibit the neural activity of LSG, thereby increasing electrophysiological stability and protecting against myocardial ischemia–induced VAs.
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The mechanisms underlying atrial fibrillation are yet to be elucidated. We sought to investigate the interactions among autonomic remodeling, epicardial adipose tissue, inflammation, and atrial ...fibrillation.
Myocardium and adjacent epicardial adipose tissue of the left atrial appendage, right atrial appendage, and pulmonary vein muscle sleeves were obtained from 61 consecutive patients (35 with atrial fibrillation, 26 with no atrial fibrillation) during mitral valve surgeries. Patients were divided into the atrial fibrillation group and no atrial fibrillation group according to the history and Holter monitoring before surgery. Sympathetic and parasympathetic innervation were evaluated by tyrosine hydroxylase and choline acetyltransferase staining, respectively. Atrial fibrosis as well as cytokines/adipokines and related inflammatory proteins and signaling pathways in the epicardial adipose tissue were examined.
Immunohistochemical studies revealed significantly increased tyrosine hydroxylase (+) and choline acetyltransferase (+) neural elements in the left atrial appendage and pulmonary vein muscle sleeve myocardium, as well as adjacent epicardial adipose tissue in the atrial fibrillation group, particularly the pulmonary vein muscle sleeve sites. The receiver operating curve identified a threshold ratio (tyrosine hydroxylase/choline acetyltransferase) of 0.8986 in the epicardial adipose tissue (sensitivity = 82.86%; specificity = 80.77%; area under the curve = 0.85, 95% confidence interval = 0.76-0.95, P < .0001). More patients with a higher tyrosine hydroxylase/choline acetyltransferase ratio (≥0.8986) had atrial fibrillation. Expression levels of the genes and related proteins of the β1 adrenergic, mitogen-activated protein kinase, and nuclear factor kappa B signaling pathways were higher in patients with a higher tyrosine hydroxylase/choline acetyltransferase ratio. The tyrosine hydroxylase/choline acetyltransferase ratio also correlated with fibrosis.
Differentially enhanced autonomic remodeling and proinflammatory and profibrotic cytokines/adipokines in the epicardial adipose tissue adjacent to the pulmonary vein muscle sleeve site may work synergistically to promote atrial fibrillation.
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Emerging evidence indicates gut microbes and their products could activate the autonomic nervous system (ANS), which plays important roles in the initiation and maintenance of atrial fibrillation ...(AF). Trimethylamine N-oxide (TMAO), a metabolite derived from gut microbes, is associated with cardiovascular diseases. The present study aimed to investigate the role of TMAO in the progression of AF.
In part 1: TMAO or saline was locally injected into 4 major atrial ganglionated plexi (GP) to clarify its effect on cardiac ANS and AF inducibility in normal canines. In part 2: TMAO or saline was injected into 4 major atrial GP to test its effect on AF progression in a rapid atrial pacing (RAP)-induced AF model.
In part 1: Local injection of TMAO significantly increased anterior right GP (ARGP) function and neural activity, shortened ERP values. In part 2, compared with the control group, 6-hour RAP significantly shortened the ERP, widened the ∑WOV, enhanced the ARGP function and neural activity, increased the NGF and c-fos expression, and up-regulated the inflammatory cytokines. TMAO aggravated all of these changes by activating the proinflammatory p65 NF-κB signaling pathway.
TMAO could increase the instability of atrial electrophysiology in normal canines and aggravate the acute electrical remodeling in a RAP-induced AF model by exacerbating autonomic remodeling. The increased inflammatory cytokines in the GP due to the activation of p65 NF-κB signaling may contribute to these effects.
•Trimethylamine N-oxide (TMAO) facilitate the progression of atrial fibrillation (AF).•The mechanism relies on the activation of cardiac autonomic nervous system (CANS).•Gut microbes may participate in the progression of AF via regulating CANS by TMAO.
Abnormal cardiac metabolism or cardiac metabolic remodeling is reported before the onset of heart failure with reduced ejection fraction (HFrEF) and is known to trigger and maintain the mechanical ...dysfunction and electrical, and structural abnormalities of the ventricle. A dysregulated cardiac autonomic tone characterized by sympathetic overdrive with blunted parasympathetic activation is another pathophysiological hallmark of HF. Emerging evidence suggests a link between autonomic nervous system activity and cardiac metabolism. Chronic β-adrenergic activation promotes maladaptive metabolic remodeling whereas cholinergic activation attenuates the metabolic aberrations through favorable modulation of key metabolic regulatory molecules. Restoration of sympathovagal balance by neuromodulation strategies is emerging as a novel nonpharmacological treatment strategy in HF. The current review attempts to evaluate the ‘neuro-metabolic axis’ in HFrEF and whether neuromodulation can mitigate the adverse metabolic remodeling in HFrEF.
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The aim of this study was to investigate whether the combination of conventional pulmonary vein isolation (PVI) by circumferential antral ablation with ganglionated plexi (GP) modification in a ...single ablation procedure, yields higher success rates than PVI or GP ablation alone, in patients with paroxysmal atrial fibrillation (PAF).
Conventional PVI transects the major left atrial GP, and it is possible that autonomic denervation by inadvertent GP ablation plays a central role in the efficacy of PVI.
A total of 242 patients with symptomatic PAF were recruited and randomized as follows: 1) circumferential PVI (n = 78); 2) anatomic ablation of the main left atrial GP (n = 82); or 3) circumferential PVI followed by anatomic ablation of the main left atrial GP (n = 82). The primary endpoint was freedom from atrial fibrillation (AF) or other sustained atrial tachycardia (AT), verified by monthly visits, ambulatory electrocardiographic monitoring, and implantable loop recorders, during a 2-year follow-up period.
Freedom from AF or AT was achieved in 44 (56%), 39 (48%), and 61 (74%) patients in the PVI, GP, and PVI+GP groups, respectively (p = 0.004 by log-rank test). PVI+GP ablation strategy compared with PVI alone yielded a hazard ratio of 0.53 (95% confidence interval: 0.31 to 0.91; p = 0.022) for recurrence of AF or AT. Fluoroscopy duration was 16 ± 3 min, 20 ± 5 min, and 23 ± 5 min for PVI, GP, and PVI+GP groups, respectively (p < 0.001). Post-ablation atrial flutter did not differ between groups: 5.1% in PVI, 4.9% in GP, and 6.1% in PVI+GP. No serious adverse procedure-related events were encountered.
Addition of GP ablation to PVI confers a significantly higher success rate compared with either PVI or GP alone in patients with PAF.