Skin sympathetic nerve activity as a biomarker for syncopal episodes during a tilt table test

Potential consequences of cardioneuroablation for vasovagal syncope: A call for appropriately designed, sham-controlled clinical trials

Cardioneuroablation (CNA) is being increasingly used to treat patients with vasovagal syncope (VVS). Bradycardia, in the cardioinhibitory subtype of VVS, results from transient parasympathetic overactivity leading to sinus bradycardia and/or atrioventricular block. By mitigating parasympathetic overactivity, CNA has been shown to improve VVS symptoms in clinical studies with relatively small sample sizes and short follow-up periods (<5 years) at selected centers. However, CNA may potentially tip the autonomic balance to a state of sympathovagal imbalance with attenuation of cardiac parasympathetic activity. A higher heart rate is associated with adverse cardiovascular events and increased mortality in healthy populations without cardiovascular diseases. Chronic sympathovagal imbalance may also affect the pathophysiology of spectra of cardiovascular disorders including atrial and ventricular arrhythmias. This review addresses potential long-term pathophysiological consequences of CNA for VVS.

Safety and efficacy of cardioneuroablation for vagal bradycardia in a single arm prospective study

Cardioneuroablation (CNA) is currently considered as a promising treatment option for patients with symptomatic bradycardia caused by vagotonia. This study aims to further investigate its safety and efficacy in patients suffering from vagal bradycardia. A total of 60 patients with vagal bradycardia who underwent CNA in the First Affiliated Hospital of Xinjiang Medical University from November 2019 to June 2022. Preoperative atropine tests revealed abnormal vagal tone elevation in all patients. First, the electroanatomic structures of the left atrium was mapped out by using the Carto 3 system, according to the protocol of purely anatomy-guided and local fractionated intracardiac electrogram-guided CNA methods. The upper limit of ablation power of superior left ganglion (SLGP) and right anterior ganglion (RAGP) was not more than 45W with an ablation index of 450.Postoperative transesophageal cardiac electrophysiological examination was performed 1 to 3 months after surgery. The atropine test was conducted when appropriate. Twelve-lead electrocardiogram, Holter electrocardiogram, and skin sympathetic nerve activity were reviewed at 1, 3, 6 and 12 months after operation. Adverse events such as pacemaker implantation and other complications were also recorded to analyze the safety and efficacy of CNA in the treatment of vagus bradycardia. Sixty patients were enrolled in the study (38 males, mean age 36.67 ± 9.44, ranging from 18 to 50 years old). None of the patients had a vascular injury, thromboembolism, pericardial effusion, or other surgical complications. The mean heart rate, minimum heart rate, low frequency, low/high frequency, acceleration capacity of rate, and skin sympathetic nerve activity increased significantly after CNA. Conversely, SDNN, PNN50, rMSSD, high frequency, and deceleration capacity of rate values decreased after CNA (all P < 0.05). At 3 months after ablation, the average heart rate, maximum heart rate, and acceleration capacity of heart rate remained higher than those before ablation, and the deceleration capacity of heart rate remained lower than those before ablation and the above results continued to follow up for 12 months after ablation (all P < 0.05). There was no significant difference in other indicators compared with those before ablation (all P > 0.05). The remaining 81.67% (49/60) of the patients had good clinical results, with no episodes of arrhythmia during follow-up. CNA may be a safe and effective treatment for vagal-induced bradycardia, subject to confirmation by larger multicenter trials.

Autonomic dysfunction and treatment strategies in intracerebral hemorrhage

AIMS

Autonomic dysfunction with central autonomic network (CAN) damage occurs frequently after intracerebral hemorrhage (ICH) and contributes to a series of adverse outcomes. This review aims to provide insight and convenience for future clinical practice and research on autonomic dysfunction in ICH patients.

DISCUSSION

We summarize the autonomic dysfunction in ICH from the aspects of potential mechanisms, clinical significance, assessment, and treatment strategies. The CAN structures mainly include insular cortex, anterior cingulate cortex, amygdala, hypothalamus, nucleus of the solitary tract, ventrolateral medulla, dorsal motor nucleus of the vagus, nucleus ambiguus, parabrachial nucleus, and periaqueductal gray. Autonomic dysfunction after ICH is closely associated with neurological functional outcomes, cardiac complications, blood pressure fluctuation, immunosuppression and infection, thermoregulatory dysfunction, hyperglycemia, digestive dysfunction, and urogenital disturbances. Heart rate variability, baroreflex sensitivity, skin sympathetic nerve activity, sympathetic skin response, and plasma catecholamine concentration can be used to assess the autonomic functional activities after ICH. Risk stratification of patients according to autonomic functional activities, and development of intervention approaches based on the restoration of sympathetic-parasympathetic balance, would potentially improve clinical outcomes in ICH patients.

CONCLUSION

The review systematically summarizes the evidence of autonomic dysfunction and its association with clinical outcomes in ICH patients, proposing that targeting autonomic dysfunction could be potentially investigated to improve the clinical outcomes.

Endocardial ablation of epicardial ganglionated plexi: history, open questions and future prospects of cardioneuroablation

Neurocardiogenic syncope is the most common cause of transient loss of consciousness and considerably reduces quality of life. Pharmacological and pacing therapy may not be fully efficacious and complications related to implanted hardware must be considered. In this context, cardioneuroablation (CNA) has been proposed to attenuate the vagal reflex with elimination of cardioinhibition. It has been shown that CNA is able to eliminate recurrences of syncope in over 90% of cases and no major complications are reported in the current literature. Despite these encouraging findings, CNA is only mentioned in current guidelines as a possible alternative treatment and has no real indication class. The diversity of mapping techniques, the absence of direct denervation control, the lack of a precise endpoint, the possible placebo effect, the short follow-up, and the question of the learning curve represent the major limitations of this promising procedure. The aim of this review was to look over the existing literature, analysing the novelties, the limitations, the unresolved issues and the outcome of CNA.

The Mechanism of Cardiac Sympathetic Activity Assessment Methods: Current Knowledge

This review has summarized the methods currently available for cardiac sympathetic assessment in clinical or under research, with emphasis on the principles behind these methodologies. Heart rate variability (HRV) and other methods based on heart rate pattern analysis can reflect the dominance of sympathetic nerve to sinoatrial node function and indirectly show the average activity level of cardiac sympathetic nerve in a period of time. Sympathetic neurotransmitters play a key role of signal transduction after sympathetic nerve discharges. Plasma or local sympathetic neurotransmitter detection can mediately display sympathetic nerve activity. Given cardiac sympathetic nerve innervation, i.e., the distribution of stellate ganglion and its nerve fibers, stellate ganglion activity can be recorded either directly or subcutaneously, or through the surface of the skin using a neurophysiological approach. Stellate ganglion nerve activity (SGNA), subcutaneous nerve activity (SCNA), and skin sympathetic nerve activity (SKNA) can reflect immediate stellate ganglion discharge activity, i.e., cardiac sympathetic nerve activity. These cardiac sympathetic activity assessment methods are all based on the anatomy and physiology of the heart, especially the sympathetic innervation and the sympathetic regulation of the heart. Technological advances, discipline overlapping, and more understanding of the sympathetic innervation and sympathetic regulation of the heart will promote the development of cardiac sympathetic activity assessment methods.

High Skin Sympathetic Nerve Activity in Patients with Recurrent Syncope

(1) Background: The autonomic imbalance plays a role in vasovagal syncope (VVS) diagnosed by head-up tilting test (HUT). neuECG is a new method of recording skin electrical signals to simultaneously analyze skin sympathetic nerve activity (SKNA) and electrocardiogram. We hypothesize that SKNA is higher in subjects with tilt-positive than tilt-negative and the SKNA surges before syncope. (2) Methods: We recorded neuECG in 41 subjects who received HUT (according to the “Italian protocol”), including rest, tilt-up, provocation and recovery phases. Data were analyzed to determine the average SKNA (aSKNA, μV) per digitized sample. Electrocardiogram was used to calculate standard deviation of normal-to-normal beat intervals (SDNN). The “SKNA-SDNN index” was calculated by rest aSKNA multiplied by the ratio of tilt-up to rest SDNN. (3) Results: 16 of 41 (39%) subjects developed syncope. The aSKNA at rest phase is significantly higher in the tilt-positive (1.21 ± 0.27 µV) than tilt-negative subjects (1.02 ± 0.29 µV) (p = 0.034). There are significant surges and withdraw of aSKNA 30 s before and after syncope (both p ≤ 0.006). SKNA-SDNN index is able to predict syncope (p < 0.001). (4) Conclusion: Higher SKNA at rest phase is associated with positive HUT. The SKNA-SDNN index is a novel marker to predict syncope during HUT.