The intrinsic autonomic nervous system in atrial fibrillation: a review

Surgical Treatment of Atrial Fibrillation

The surgical treatment of atrial fibrillation (AF) has evolved significantly over the last 20 years and even more so in the last 5 years. There are now many clinically successful surgical procedures focused on eliminating AF and AF-related stroke. This review discusses the current types of surgical AF procedures, including minimally invasive and hybrid, and may assist clinicians in understanding the various surgical AF options available to patients today.

Impact of Yoga on Cardiac Autonomic Function and Arrhythmias

With the expanding integration of complementary and alternative medicine (CAM) practices in conjunction with modern medicine, yoga has quickly risen to being one of the most common CAM practices across the world. Despite widespread use of yoga, limited studies are available, particularly in the setting of dysrhythmia. Preliminary studies demonstrate promising results from integration of yoga as an adjunct to medical therapy for management of dysrhythmias. In this review, we discuss the role of autonomic nervous system in cardiac arrhythmia,interaction of yoga with autonomic tone and its subsequent impact on these disease states. The role of yoga in specific disease states, and potential future direction for studies assessing the role of yoga in dysrhythmia.

A novel strategy to treat vaso-vagal syncope: Cardiac neuromodulation by cryoballoon pulmonary vein isolation

Background

Clinical management of vaso-vagal syncope (VVS) remains challenging since no therapy has proven to completely prevent VVS recurrence.

Objective

The purpose of this study was to analyze the mid-term outcome of cryoballoon (CB) cardioneuroablation achieved by pulmonary vein isolation (PVI) in patients with VVS.

Methods

Patients who underwent CB cardioneuroablation in our centers between January 2014 to June 2018 were included. All patients had a history of VVS or pre-syncope despite therapeutic attempts with medical and/or pacing treatments. Patients were excluded in case of structural heart diseases, cerebrovascular diseases or suspected drug-related syncope. Both heart rate (HR) and atrio-ventricular (AV) interval were analyzed on the 12-lead electrocardiogram (ECG) the day before the procedure, the day after, and in the follow-up.

Results

In total, 26 patients (76.9% males, 37.5 ± 9.0 years old) were included. All patients underwent a successful procedure with the 28 mm second-generation Arctic Front Advance CB. No major complication occurred. At a mean follow-up of 20.1 ± 11.6 months the freedom from VVS or reflex pre-syncope was 83,7%, with 22 patients free from any clinical recurrence. Basal HR significantly increased the day after the procedure (57.2 bpm vs 78.3 bpm, p < 0.001), while at the final follow-up it stabilized at a value halfway between the 2 previous ones (69.8 bpm, p = 0.0086). The AV interval didn’t modify significantly after the procedure.

Conclusion

Endocardial autonomic denervation achieved by CB PVI appears to be an effective and safe treatment option for patients with refractory VVS and reflex pre-syncope.

[The First in Russia Experience of Successful Implementation of Constant Neurostimulation of the Spinal Cord in the Complex Treatment of a Patient with Permanent Form of Atrial Fibrillation Combined with Spinal Stenosis]

This article describes for the first time in the domestic literature a clinical case of the therapeutic effect of neuromodulation on the permanent form of atrial fibrillation and chronic heart failure in an elderly patient with spinal stenosis which led to the development of pain syndrome and movement disorders. For the treatment of neurological pathology, at the beginning epidural administration of drugs was applied, followed by spinal cord stimulation trial and implantation of permanent neurostimulator. At each stage of treatment conducted by a functional neurosurgeon the patient had a spontaneous restoration of sinus rhythm, and during continuous neurostimulation a stable retention of sinus rhythm and regression of heart failure symptoms have been observed throughout a long observation period. The article also presents the data of a few experimental and clinical studies on the use of neuromodulation in cardiology, describes the method of implantation of spinal electrodes and analyzes possible mechanisms of modulation of the autonomic innervation of the heart, implemented by spinal cord stimulation.

Is ganglionated plexus ablation effective for treating atrial fibrillation?

PURPOSE

Very few studies have investigated the efficacy of ganglionated plexus ablation during the conventional maze procedure. In this study, we sought to evaluate its additive effect in reducing recurrent atrial fibrillation after concomitant maze surgery.

METHODS

A retrospective study was conducted of 79 patients who underwent Cox maze IV concomitantly with open-heart surgery with (GP group) or without (Maze group) ganglionated plexus mapping. All active ganglionated plexuses were ablated. The two groups were compared and their follow-up data were analyzed.

RESULTS

Active ganglionated plexuses were found in 81% of patients who underwent ganglionated plexus mapping. The rates of freedom from atrial fibrillation at 1 year in the GP and Maze groups were 77 and 75%, respectively. The cumulative freedom from atrial fibrillation at follow-up (27.7 ± 17.3 months) was comparable in the two groups (p = 0.427). A multivariate analysis revealed that persistent atrial fibrillation for more than 90 months was an independent predictor of recurrent atrial fibrillation.

CONCLUSION

Ganglionated plexus ablation with Cox maze IV did not reduce the incidence of recurrent atrial fibrillation in comparison to Maze alone.

Atrial fibrillation electrical remodelling via ablation of the epicardial neural networks and suprathreshold stimulation of vagosympathetic nerve

Background

Numerous studies have shown that the cardiac autonomic nervous system (CANS) is involved in the occurrence and persistence of atrial fibrillation (AF). The CANS is commonly considered to consist of the extrinsic and intrinsic autonomic nerves. The influence of exogenous and endogenous nerve stimulation plexus ablation on pulmonary vein sleeves and atrial myocardium provides important information in understanding the occurrence and persistence of AF. Vagosympathetic nerve stimulation and epicardial neural networks are important participants in atrial electrical remodelling (AER). Elucidation of the changes in the electrophysiological indicators of the atrial and pulmonary veins caused by epicardial neural network ablation and autonomic nerve stimulation may provide a theoretical basis for the clinical treatment of AF.

Material/Methods

A total of 13 beagle dogs were randomly divided into 2 groups: the control group (n=6), which was treated with a simple rapid atrial pacing (RAP) for 6 h, and the experimental group (n=7), which was treated with RAP+vagus nerve stimulation (VNS) for 6 h. Both groups were treated with epicardial ganglia plexus (GP) ablation after 6 h. We measured the monophasic action potential (MAP), various parts of the effective refractory period (ERP), and AF induction rate before and after pacing or ablation.

Results

With the extension of the pacing time, the atrial MAP and ERP of the 2 groups shortened and returned to normal after ablation plexus. After GP ablation, the atrial AF-induced rate did not decrease significantly compared with that of the pulmonary vein.

Conclusions

Vagus nerve threshold stimulation exacerbated the deterioration of electrical remodelling, whereas the epicardial neural network ablation blocked or reversed the AER.

Destruction Of Medium Already Afected By Destructive Disorder: Fibrillating Atria Conceptually Need Therapeutic Help Rather Than Surgical Or Ablative Destruction

Atrial fibrillation (AF) as the most common supraventricular arrhythmia is scarcely amenable to contemporary treatment. Due to the diverse origin and variable clinical course of AF there is a broad spectrum of therapy options. However, optimal AF management has not become a gold standard yet. In general, the recurrence rate of AF is most often clinically unacceptable despite drug, surgical and/or ablation therapy. Substrate-based approach and ongoing ablation of atrial wall in its selected areas including the vicinity of pulmonary veins can be harmful. Applied physical factors do produce total disintegration of cardiomyocites - both intra- and inter-cellular damage which, in turn, leads to functional hypo-/inactivation of atria irrespective of whether the sinus rhythm is restored or not. In fact, iatrogenic phenomenon of ablation-induced atrial incompetence did emerge. Heterogeneity in clinical results reflects the uncertainty regarding the efficacy, risks and benefits of invasive AF therapy. In this regard the overall burden of AF may increase when using current therapy methods. Applicability of destructive techniques is yet to be fully elucidated and discussed. We hypothesize that currently used ablation and/or surgical techniques are potentially harmful since the success rates are likely achieved through violation of atrial myocardium. That is why a new and well-designed therapeutic strategy is needed. Invention of highly selective curative methods producing fibrillatory/electric blockage with concomitant saving of atrial transport function is to be encouraged.

Device-Based Approaches to Modulate the Autonomic Nervous System and Cardiac Electrophysiology

Alterations in resting autonomic tone can be pathogenic in many cardiovascular disease states, such as heart failure and hypertension. Indeed, autonomic modulation by way of beta-blockade is a standard treatment of these conditions. There is a significant interest in developing non-pharmacological methods of autonomic modulation as well. For instance, clinical trials of vagal stimulation and spinal cord stimulation in the treatment of heart failure are currently underway, and renal denervation has been studied recently in the treatment of resistant hypertension. Notably, autonomic stimulation is also a potent modulator of cardiac electrophysiology. Manipulating the autonomic nervous system in studies designed to treat heart failure and hypertension have revealed that autonomic modulation may have a role in the treatment of common atrial and ventricular arrhythmias as well. Experimental data on vagal nerve and spinal cord stimulation suggest that each technique may reduce ventricular arrhythmias. Similarly, renal denervation may play a role in the treatment of atrial fibrillation, as well as in controlling refractory ventricular arrhythmias. In this review, we present the current experimental and clinical data on the effect of these therapeutic modalities on cardiac electrophysiology and their potential role in arrhythmia management.

Role of the autonomic nervous system in atrial fibrillation: pathophysiology and therapy

Autonomic nervous system activation can induce significant and heterogeneous changes of atrial electrophysiology and induce atrial tachyarrhythmias, including atrial tachycardia and atrial fibrillation (AF). The importance of the autonomic nervous system in atrial arrhythmogenesis is also supported by circadian variation in the incidence of symptomatic AF in humans. Methods that reduce autonomic innervation or outflow have been shown to reduce the incidence of spontaneous or induced atrial arrhythmias, suggesting that neuromodulation may be helpful in controlling AF. In this review, we focus on the relationship between the autonomic nervous system and the pathophysiology of AF and the potential benefit and limitations of neuromodulation in the management of this arrhythmia. We conclude that autonomic nerve activity plays an important role in the initiation and maintenance of AF, and modulating autonomic nerve function may contribute to AF control. Potential therapeutic applications include ganglionated plexus ablation, renal sympathetic denervation, cervical vagal nerve stimulation, baroreflex stimulation, cutaneous stimulation, novel drug approaches, and biological therapies. Although the role of the autonomic nervous system has long been recognized, new science and new technologies promise exciting prospects for the future.

Experimental evaluation of the cardiac rhythm originating in myocardial sleeves of pulmonary veins using a monophasic action potential

Spontaneous depolarization similar to that from the sinus node was documented from the myocardial sleeves of pulmonary veins (PV) after isolation procedures. It was then hypothesized that sinus node-like tissue is present in the PVs of humans. Based on a number of features, the myocardium of myocardial sleeves (MS) is highly arrhythmogenic. Membrane potentials originating from MS are invariably recordable at the PVs ostia in patients with atrial fibrillation (AF) and delayed conduction around the PVs ostia may play a role in re-entry process responsible for the initiation and maintenance of AF. Diagnostic and therapeutic evidence of premature atrial beats induced in MS of PVs and resulting in launch of AF was detected by 3D electroanatomic method of monophasic action potential (MAP). MAP recording plays an important role in a direct view of human myocardial electrophysiology under both physiological and pathological conditions. Its crucial importance lies in the fact that it enables the study of the action potential of myocardial cell in vivo and, therefore, the study of the dynamic relation of this potential with all the organism variables. The knowledge of pathological MAPs from PV myocardial sleeves can help us to confirm a diagnosis when finding the similar action potential morphology. MAP can be also used to evaluate the therapeutic efficiency of vagal nerves suppression, radiofrequency ablation or other treatment procedures in PVs myocardial sleeves as well as for post-treatment following up.

Postoperative Atrial Fibrillation: Year 2011 Review of Predictive and Preventative Factors of Atrial Fibrillation Post Cardiac Surgery

Background: Post cardiac surgery atrial fibrillation is common after cardiac surgery. Despite the advances in medical and surgical treatment, its incidence remains high and unchanged for decades. The aim of this review was to summarize studies published in 2011 on identifying factors, prevention strategies, treatment and effect of post operative atrial fibrillation (POAF) on the outcome after cardiac surgery. Methods: A review was performed on Medline, Embase and Chocrane on all of the English-language, peer-reviewed published clinical studies on POAF; studies investigating the mechanism of developing POAF, prevention, treatment and outcome were all included and analyzed. Case reports, studies on persistent/preoperative atrial fibrillation (AF), POAF after cardiac transplant, congenital cases and nonclinical studies were all excluded. We have also valuated these studies based on the type of the study, their originality, impact factor of the journal and their limitations. Results: Overall 62 studies were reviewed and analyzed; 26 on POAF predictive factors, 31 on preventative strategies and 6 on the outcome of POAF. Of these studies only two were original and the remaining were either performed in AF in general population (n=10) or had been studied and reported several times before in cardiac surgery (n=50). The average impact factor of the journals that POAF was published in was only 2.8 ranging between 0.5 and 14.5. Conclusion: Post cardiac surgery atrial fibrillation is a multi-factorial and complex condition. Cardiac surgery may be a risk factor for developing POAF in patients already susceptible to this condition and may not be a complication of cardiac surgery. Future studies should mainly focus on histological changes in the conductive tissue of atrium and related treatment strategies rather than predictive factors of POAF and more funding should be made available to study this condition from new and entirely different perspectives.