Autonomic Modulation

Abstract

A variety of experimental and clinical reports have engendered a different approach to cardiac arrhythmias as well as other cardiovascular conditions. The focus of a new paradigm is the autonomic nervous system and its important role in various pathological states. From an overall standpoint, this new paradigm can be encompassed by the term "autonomic modulation," which would include autonomic nerve stimulation or autonomic denervation to modulate the autonomic activity in physiological or pathophysiological functions of the heart as well as other visceral organ systems. Article see p 279Vaso-vagal syncope is the most common form of neurally mediated syncope. 1 The pathophysiology of vaso-vagal syncope is still controversial, but it is thought to be related to prolonged orthostatic stress, which causes increased peripheral venous pooling with a subsequent fall in venous return to the heart. This in turn causes a hypercontractile state, which leads to activation of ventricular mechanoreceptors and a sudden increase in the afferent neural traffic to the brain. The result is sympathetic withdrawal and parasympathetic enhancement that manifests as hypotension (vasodepressor type), bradycardia (cardioinhibitory type), and syncope. 1 In other words, vaso-vagal syncope is a disorder caused by an abnormally amplified autonomic reflex involving both sympathetic and parasympathetic components. Over the past 2 decades, ␤-blockers, ␣-agonists, mineralocorticoids, selective serotonin reuptake inhibitors, and dual-chamber pacemaker implantation all produced initial promising but later disappointing results. 1-3 Vaso-vagal syncope continues to be a vexing clinical arrhythmia.In this issue of Circulation Arrhythmia and Electrophysiology, Yao et al 4 reported 10 patients who had drug-refractory, frequent, and highly symptomatic vaso-vagal syncope. Based on the hypothesis that vaso-vagal syncope is related to enhanced parasympathetic activity, the authors performed autonomic denervation by targeting the 4 major atrial ganglionated plexi (GP), guided by high-frequency stimulation as described by the Oklahoma group (Po et al 5 ). The left superior GP, right anterior GP and left inferior GP were identified and ablated in 10 (100%), 5 (50%), and 3 (30%) patients, respectively. Surprisingly, the right inferior GP, often referred to as the atrioventricular nodal GP, did not respond to high-frequency stimulation in any patient and was therefore not ablated. The authors did not show the presumed right inferior GP area where high-frequency stimulation was delivered. However, location of the right anterior GP as shown in Figure 1 in the article is not the typical location of the right anterior GP (at the left atrial septum, near the carina of the right pulmonary veins). 5 It is possible that high-frequency stimulation might not have been delivered to the correct location of the right inferior GP. Another technical problem is that ablation was performed using an 8-mm, nonirrigated catheter, which carries a significant risk for thromboemboli...

Nonpharmacological Approach to Managing Atrial Fibrillation: A Review

“…Autonomic modulation stands apart from alternative atrial fibrillation treatments by centering on the autonomic nervous system's role in driving and perpetuating cardiac arrhythmias, particularly atrial fibrillation [92,94]. Experimental models, such as vagal activation, offer insights into neural mechanisms and the impact of neuromodulation, evident in its ability to limit infarct size and protect against ventricular arrhythmias during myocardial infarction [97]. These models facilitate a deeper understanding of neural mechanisms and the effects of autonomic modulation [98].…”

Cardioneuroablation: Catheter Vagal Denervation as a New Therapy for Cardioinhibitory Syncope

“…The properties of the atrial wall and may be identified by changes in the spectrum as "AF Nests" [22][23][24][25] (this name resulted from its relation with the AF physiopathology as they present electrical resonance 26,27 favoring the AF maintenance).…”

Ganglionated Plexi Ablation: Physiology and Clinical Applications

“…49,50 In contrast to pharmacological therapy and pacemaker implantation, GP ablation for vasovagal syncope provides a means of targeting the root of the problem, which includes disturbances of the intrinsic CANS. 51 GP ablation for vasovagal syncope was first introduced by Yao et al, who reported their initial experience on 10 patients with highly symptomatic vasovagal syncope. 52 Selective highfrequency stimulation-guided GP ablation resulted in an impressive amelioration of their prodromal symptoms and no recurrence of syncope over 30 months of follow up.…”