Neuraxial modulation for refractory ventricular arrhythmias: value of thoracic epidural anesthesia and surgical left cardiac sympathetic denervation

A novel sympathetic neuronal GABAergic signalling system regulates NE release to prevent ventricular arrhythmias after acute myocardial infarction

AIM

Overactivation of the sympathetic nerve may lead to severe ventricular arrhythmias (VAs) after myocardial infarction (MI). Thus, targeting sympathetic nerve activity is an effective strategy to prevent VAs clinically. The superior cervical ganglion (SCG), the extracardiac sympathetic ganglion innervating cardiac muscles, has been found to have a GABAergic signalling system, the physiological significance of which is obscure. We aimed to explore the functional significance of SCG post MI and whether the GABAergic signal system is involved in the process.

METHODS

Adult male Sprague-Dawley rats were divided into seven different groups. Rats in the MI groups underwent ligation of the left anterior descending coronary artery. All animals were used for electrophysiological testing, renal sympathetic nerve activity (RSNA) testing, and ELISA. Primary SCG sympathetic neurons were used for the in vitro study.

RESULTS

The GABAA receptor agonist muscimol significantly decreased the ATP-induced increase in intracellular Ca2+ (P < 0.05). GABA treatment in MI rats significantly attenuated the level of serum and cardiac norepinephrine (NE; P < 0.05). Sympathetic activity and inducible VAs were also lower in MI + GABA rats than in MI rats (P < 0.05). Knockdown of the GABAA Rs β2 subunit (GABAA Rβ2 ) in the SCG of MI rats increased the NE levels in serum and cardiac tissue, RSNA and inducible VAs compared with vehicle shRNA (P < 0.05).

CONCLUSION

The GABAergic signalling system is functionally expressed in SCG sympathetic neurons, and activation of this system suppresses sympathetic activity, thereby facilitating cardiac protection and making it a potential target to alleviate VAs.

Update on prevention and treatment of sudden cardiac arrest

Sudden cardiac arrest is the leading cause of cardiovascular mortality, posing a substantial public health burden. The incidence and epidemiology of sudden death are a function of age, with primary arrhythmia syndromes and inherited cardiomyopathies representing the predominant causes in younger patients, while coronary artery disease being the leading etiology in those who are 35 years of age and older. Internal cardioverter defibrillators remain the mainstay of primary and secondary prevention of sudden cardiac arrest. In the acute phase, cardiac chain of survival, early reperfusion, and therapeutic hypothermia are the key steps in improving outcomes. In the chronic settings, ventricular tachycardia ablation has been shown to improve patients' quality of life by reducing frequency of defibrillator shocks. Moreover, recent studies have suggested that it may increase survival. Neuromodulation represents a novel therapeutic modality that has a great potential for improving treatment of ventricular arrhythmias.

Carotid baroreceptor stimulation suppresses ventricular fibrillation in canines with chronic heart failure

Carotid baroreceptor stimulation (CBS) has been shown to improve cardiac dysfunction and pathological structure remodelling. This study aimed to investigate the effects of CBS on the ventricular electrophysiological properties in canines with chronic heart failure (CHF). Thirty-eight beagles were randomized into control (CON), CHF, low-level CBS (LL-CBS), and moderate-level CBS (ML-CBS) groups. The CHF model was established with 6 weeks of rapid right ventricular pacing (RVP), and concomitant LL-CBS and ML-CBS were applied in the LL-CBS and ML-CBS groups, respectively. After 6 weeks of RVP, ventricular electrophysiological parameters and left stellate ganglion (LSG) neural activity and function were measured. Autonomic neural remodelling in the LSG and left ventricle (LV) and ionic remodelling in the LV were detected. Compared with the CHF group, both LL-CBS and ML-CBS decreased spatial dispersion of action potential duration (APD), suppressed APD alternans, reduced ventricular fibrillation (VF) inducibility, and inhibited enhanced LSG neural discharge and function. Only ML-CBS significantly inhibited ventricular repolarization prolongation and increased the VF threshold. Moreover, ML-CBS inhibited the increase in growth-associated protein-43 and tyrosine hydroxylase-positive nerve fibre densities in LV, increased acetylcholinesterase protein expression in LSG, and decreased nerve growth factor protein expression in LSG and LV. Chronic RVP resulted in a remarkable reduction in protein expression encoding both potassium and L-type calcium currents; these changes were partly amended by ML-CBS and LL-CBS. In conclusion, CBS suppresses VF in CHF canines, potentially by modulating autonomic nerve and ion channels. In addition, the effects of ML-CBS on ventricular electrophysiological properties, autonomic remodelling, and ionic remodelling were superior to those of LL-CBS.

Effective Use of Percutaneous Stellate Ganglion Blockade in Patients With Electrical Storm

Background:

Percutaneous stellate ganglion blockade (SGB) has been used for drug-refractory electrical storm due to ventricular arrhythmia (VA); however, the effects and long-term outcomes have not been well studied.

Methods:

This study included 30 consecutive patients who had drug-refractory electrical storm and underwent percutaneous SGB between October 1, 2013, and March 31, 2018. Bupivacaine, alone or combined with lidocaine, was injected into the neck with good local anesthetic spread in the vicinity of the left stellate ganglion (n=15) or both stellate ganglia (n=15). Data were collected for patient clinical characteristics, immediate and long-term outcomes, and procedure-related complications.

Results:

Clinical characteristics included age, 58±14 years; men, 73.3%; and left ventricular ejection fraction, 34±16%. At 24 hours, 60% of patients were free of VA. Patients whose VA was controlled had a lower hospital mortality rate than patients whose VA continued (5.6% versus 50.0%; P =0.009). Implantable cardioverter-defibrillator interrogation showed a significant 92% reduction in VA episodes from 26±41 to 2±4 in the 72 hours after SGB ( P <0.001). Patients who died during the same hospitalization (n=7) were more likely to have ischemic cardiomyopathy (100% versus 43.5%; P =0.03) and recurrent VA within 24 hours (85.7% versus 26.1%; P =0.009). There were no procedure-related major complications.

Conclusions:

SGB effectively attenuated electrical storm in more than half of patients without procedure-related complications. Percutaneous SGB may be considered for stabilizing ventricular rhythm in patients for whom other therapies have failed.

Neuromodulation for the Treatment of Heart Rhythm Disorders

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Derangement of autonomic nervous signaling is an important contributor to cardiac arrhythmogenesis.

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Modulation of autonomic nervous signaling holds significant promise for the prevention and treatment of cardiac arrhythmias.

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Further clinical investigation is necessary to establish the efficacy and safety of autonomic modulatory therapies in reducing cardiac arrhythmias.

There is an increasing recognition of the importance of interactions between the heart and the autonomic nervous system in the pathophysiology of arrhythmias. These interactions play a role in both the initiation and maintenance of arrhythmias and are important in both atrial and ventricular arrhythmia. Given the importance of the autonomic nervous system in the pathophysiology of arrhythmias, there has been notable effort in the field to improve existing therapies and pioneer additional interventions directed at cardiac-autonomic targets. The interventions are targeted to multiple and different anatomic targets across the neurocardiac axis. The purpose of this review is to provide an overview of the rationale for neuromodulation in the treatment of arrhythmias and to review the specific treatments under evaluation and development for the treatment of both atrial fibrillation and ventricular arrhythmias.

Neuromodulation for Ventricular Tachycardia and Atrial Fibrillation: A Clinical Scenario-Based Review

Autonomic dysregulation in cardiovascular disease plays a major role in the pathogenesis of arrhythmias. Cardiac neural control relies on complex feedback loops consisting of efferent and afferent limbs, which carry sympathetic and parasympathetic signals from the brain to the heart and sensory signals from the heart to the brain. Cardiac disease leads to neural remodeling and sympathovagal imbalances with arrhythmogenic effects. Preclinical studies of modulation at central and peripheral levels of the cardiac autonomic nervous system have yielded promising results, leading to early stage clinical studies of these techniques in atrial fibrillation and refractory ventricular arrhythmias, particularly in patients with inherited primary arrhythmia syndromes and structural heart disease. However, significant knowledge gaps in basic cardiac neurophysiology limit the success of these neuromodulatory therapies. This review discusses the recent advances in neuromodulation for cardiac arrhythmia management, with a clinical scenario-based approach aimed at bringing neurocardiology closer to the realm of the clinical electrophysiologist.

Update in Electrical Storm Therapy

BACKGROUND

Electrical storm (ES) is a major life-threatening event, which announces a possible negative outcome and poor prognosis and poses challenging questions concerning etiology and management.

DATA SOURCES

A literature search was conducted through MEDLINE and EMBASE (past 30 years until the end of September 2018) using the following search terms: ES, ventricular fibrillation, ventricular tachycardia, ablation, and implantable defibrillator. Clinicaltrials.gov was also consulted for studies that are ongoing or completed. Additional articles were identified through bibliographical citations.

AREA OF UNCERTAINTY

There is no homogeneous attitude, and therapeutic strategies vary widely.

THERAPEUTIC ADVANCES

The aim of this review is to define the concept of ES, to review the incidence and prognostic implications, and to describe the most common strategies of therapeutic advances and trends. The management strategy should be decided after an accurate risk stratification is done in initial evaluation according to hemodynamic tolerability and presence of triggers and comorbidities. General care should be provided in an intensive cardiovascular care unit. The cornerstone of acute medical therapy used in ES is mainly represented by amiodarone and beta-blockers. Deep sedation and mechanical ventilation should provide comfort for treatment administration. First-choice drugs are benzodiazepines and short-acting analgesics. General care may also include thoracic epidural anesthesia to modulate neuroaxial efferents to the heart and to decrease sympathetic hyperactivity. We include a special focus on ablation as a reliable tool to target the mechanism of arrhythmia, finally building an up-to-date standardization.

CONCLUSIONS

ES management needs a complex assessment and interpretation of a critical situation in a life-threatening condition. Optimal implantable cardioverter-defibrillator-reprogramming, antiarrhythmic drug therapy and sedation are in first-line approach. Catheter ablation is the elective therapy and plays a central key role in the treatment of ES if possible in combination with hemodynamic support.

Is renal denervation still a treatment option in cardiovascular disease?

The role of renal sympathetic denervation (RDN) has been the topic of ongoing debate ever since the impressive initial results. The rationale of RDN is strong and supported by non-clinical studies, which lies in uncoupling the autonomic nervous crosstalk between the kidneys and the central nervous system. Since we know that cardiovascular diseases, such as hypertension, atrial, ventricular arrhythmias and heart failure (HF) are related to sympathetic (over)activity, modulation of the renal nerve activity appears to be a reasonable and attractive therapeutic target in these patients. This review will focus on the existing evidence and potential future perspectives for RDN as treatment option in cardiovascular disease.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Neuromodulation Approaches for Cardiac Arrhythmias: Recent Advances

PURPOSE OF REVIEW

This review aims to describe the latest advances in autonomic neuromodulation approaches to treating cardiac arrhythmias, with a focus on ventricular arrhythmias.

RECENT FINDINGS

The increasing understanding of neuronal remodeling in cardiac diseases has led to the development and improvement of novel neuromodulation therapies targeting multiple levels of the autonomic nervous system. Thoracic epidural anesthesia, spinal cord stimulation, stellate ganglion modulatory therapies, vagal stimulation, renal denervation, and interventions on the intracardiac nervous system have all been studied in preclinical models, with encouraging preliminary clinical data. The autonomic nervous system regulates all the electrical processes of the heart and plays an important role in the pathophysiology of cardiac arrhythmias. Despite recent advances in the clinical application of cardiac neuromodulation, our comprehension of the anatomy and function of the cardiac autonomic nervous system is still limited. Hopefully in the near future, more preclinical data combined with larger clinical trials will lead to further improvements in neuromodulatory treatment for heart rhythm disorders.

Autonomic Neuromodulation for Preventing and Treating Ventricular Arrhythmias

The cardiac autonomic nervous system (CANS) is associated with modulation of cardiac electrophysiology and arrhythmogenesis. In this mini review, we will briefly introduce cardiac autonomic anatomy and autonomic activity in ventricular arrhythmias (VAs) and discuss novel approaches of CANS modulation for treating VAs. Studies over the decades have provided a better understanding of cardiac autonomic innervation and revealed overwhelming evidence of the relationship between autonomic tone and VAs. A high sympathetic tone and low parasympathetic (vagal) tone are considered as the major triggers of VAs in patients with myocardial ischemia, which can cause sudden cardiac death. In recent years, novel methods of autonomic neuromodulation have been investigated to prevent VAs, and they have been verified as being beneficial for malignant VAs in animal models and humans. The clinical outcome of autonomic neuromodulation depends on the level of cardiac neuraxis, stimulation parameters, and patient's pathological status. Since autonomic modulation for VA treatment is still in the early stage of clinical application, more basic and clinical studies should be performed to clarify these mechanisms and optimize autonomic neuromodulation therapies for patients with VAs in the future.

Sympathetic Nervous System Activation and Its Modulation: Role in Atrial Fibrillation

The autonomic nervous system (ANS) has a significant influence on the structural integrity and electrical conductivity of the atria. Aberrant activation of the sympathetic nervous system can induce heterogeneous changes with arrhythmogenic potential which can result in atrial tachycardia, atrial tachyarrhythmias and atrial fibrillation (AF). Methods to modulate autonomic activity primarily through reduction of sympathetic outflow reduce the incidence of spontaneous or induced atrial arrhythmias in animal models and humans, suggestive of the potential application of such strategies in the management of AF. In this review we focus on the relationship between the ANS, sympathetic overdrive and the pathophysiology of AF, and the potential of sympathetic neuromodulation in the management of AF. We conclude that sympathetic activity plays an important role in the initiation and maintenance of AF, and modulating ANS function is an important therapeutic approach to improve the management of AF in selected categories of patients. Potential therapeutic applications include pharmacological inhibition with central and peripheral sympatholytic agents and various device based approaches. While the role of the sympathetic nervous system has long been recognized, new developments in science and technology in this field promise exciting prospects for the future.

Video-assisted thoracoscopic cardiac denervation of refractory ventricular arrhythmias and electrical storms: a single-center series

BACKGROUND

The combined treatment of beta-blockers with ablation and Implanted cardioverter defibrillation therapy, continues to be the mainstay treatment for ventricular arrhythmias (VAs). Despite treatment, some patients remain refractory.  Recent studies have shown success rates using video-assisted thoracoscopic (VATS) cardiac denervation as an effective therapeutic option for these patients.

CASE SERIES PRESENTATION

During a period of three years, from 2015 through 2017, twenty patients (N = 20) failed traditional medical and interventional treatment for the management of ventricular arrhythmias and electrical storms. After remaining refractory, the patients were referred to our thoracic surgery department for a VATS based treatment. The patients all had ventricular arrhythmias and electrical storms secondary to different cardiomyopathies. The patients were refractory to combined medical (beta-blockers), Implanted Cardioverter defibrillation (ICD) and ablation therapy. All twenty patients agreed to surgery and were taken to cardiac denervation using a bilateral VATS approach by two thoracic surgeons at a single Cardiothoracic center. During the month prior to bilateral VATS denervation a combined total of twenty-nine (N = 29) ICD shocks were registered in addition to six (N = 6) cases of electrical storms averaging three (N = 3) shocks per day. Mean shocks per patient was 2.3. During the first three months following VATS, the patients had a 90% (N = 18/20) total resolution of ICD registered shocks, a 100% (N = 6/6) resolution of electrical storms, and a 92% (N = 11/12) resolution of shocks in patients having previous ablation therapy. No complications were documented following surgery except for one case of pneumothorax as a result of the procedure, and there were no peri-operative mortalities.

CONCLUSIONS

Bilateral thoracoscopic cardiac denervation can be a safe and seemingly effective therapeutic option for patients presenting with life-threatening refractory ventricular arrhythmias and electrical storms in a variety of cardiomyopathies including Chagas disease.

Management of ventricular storm with thoracic epidural anesthesia

The incidence of recurrent ventricular arrhythmias is increasing these days. Ventricular electrical storm can be of three types as follows: monomorphic ventricular tachycardia (VT), polymorphic VT, and ventricular fibrillation. The mechanism of ventricular storm is complex, and its management is quite a challenge for the clinicians due to its life-threatening consequences. We report a case of ventricular storm in whom all the conventional methods for the management of arrhythmias were ineffective, and the case is managed effectively with thoracic epidural anesthesia (TEA). A 60-year-old male patient was admitted to recurrent ventricular arrhythmias. He received defibrillator shocks and other antiarrhythmic drugs, but he was not responding to the treatment. We managed to revert the ventricular arrhythmias to the sinus rhythm with TEA. Ventricular storm is a challenging complication, which can be managed effectively with timely diagnosis and effective management.

Thoracic Epidural Blockade for Ventricular Tachycardia Storm in Patient with Takotsubo Cardiomyopathy

Introduction

Takotsubo cardiomyopathy is acute nonischemic myocardial dysfunction of the left and/or right ventricle which usually recovers completely within several days to weeks. We report a case where thoracic epidural analgesia was used to manage sympathetic storm in Takotsubo cardiomyopathy.

Case description

A 58-year-old diabetic female who was being treated for urinary tract infection and diabetic ketoacidosis for the past 2 days sustained an episode of pulseless ventricular tachycardia which was treated as per ACLS protocol. Troponin levels were raised, and 2D echocardiography was showing "Takotsubo cardiomyopathy" with typical apical ballooning of the left ventricle at the time of admission, and she was mechanically ventilated and receiving vasopressors. She continued to get episodes of ill-sustained ventricular tachycardia. In spite of conventional management, episodes of ill-sustained ventricular tachycardia continued, and hence, sympathetic blockade with thoracic epidural catheter was administered to control the ventricular tachycardia storm.

Conclusion

Sympathetic blockade to treat ventricular tachycardia is a promising approach which needs to be validated with more evidence.

How to cite this article

Ashwini J, Durgesh M, Girish D. Thoracic Epidural Blockade for Ventricular Tachycardia Storm in Patient with Takotsubo Cardiomyopathy. IJCCM 2019;23(11):529-532.

Ageing, the autonomic nervous system and arrhythmia: From brain to heart

An ageing myocardium possesses significant electrophysiological alterations that predisposes the elderly patient to arrhythmic risk. Whilst these alterations are intrinsic to the cardiac myocytes, they are modulated by the cardiac autonomic nervous system (ANS) and consequently, ageing of the cardiac ANS is fundamental to the development of arrhythmias. A systems-based approach that incorporates the influence of the cardiac ANS could lead to better mechanistic understanding of how arrhythmogenic triggers and substrates interact spatially and temporally to produce sustained arrhythmia and why its incidence increases with age. Despite the existence of physiological oscillations of ANS activity on the heart, pathological oscillations can lead to defective activation and recovery properties of the myocardium. Such changes can be attributable to the decrease in functionality and structural alterations to ANS specific receptors in the myocardium with age. These altered ANS adaptive responses can occur either as a normal ageing process or accelerated in the presence of specific cardiac pathologies, such as genetic mutations or neurodegenerative conditions. Targeted intervention that seek to manipulate the ageing ANS influence on the myocardium may prove to be an efficacious approach for the management of arrhythmia in the ageing population.

Calming the Electrical Storm: Use of Stellate Ganglion Block and Thoracic Epidural in Intractable Ventricular Tachycardia

Imbalances in the autonomic nervous system contribute to ventricular tachyarrhythmias. Sympatholysis with thoracic epidural analgesia or a stellate ganglion block attenuates myocardial excitability and the proarrhythmic effects of sympathetic hyperactivity.

Functional selectivity of cardiac preganglionic sympathetic neurones in the rabbit heart

BACKGROUND

Studies have shown regional and functional selectivity of cardiac postganglionic neurones indicating there might exist a similar heterogeneity in spinal segmental preganglionic neurones, which requires further investigation.

METHODS

Right and left sympathetic chains were electrically stimulated from T6 to T1 in the innervated isolated rabbit heart preparation (n = 18). Sinus rate, left ventricular pressure, retrograde ventriculo-atrial conduction, monophasic action potential duration, effective refractory period, ventricular fibrillation threshold and electrical restitution were measured.

RESULTS

Right sympathetic stimulation had a greater influence on heart rate (T1-T2: right; 59.9 ± 6.0%, left; 41.1 ± 5.6% P < 0.001) and left stimulation had greater effects on left ventricular pressure (T1-T2: right; 20.7 ± 3.2%, left; 40.3 ± 5.4%, P < 0.01) and ventriculo-atrial conduction (T1-T2: right; -6.8 ± 1.1%, left; -15.5 ± 0.2%) at all levels, with greater effects at rostral levels (T1-T3). Left sympathetic stimulation caused shorter monophasic action potentials at the base (T4-T5: right; 119.3 ± 2.7 ms, left; 114.7 ± 2.5 ms. P < 0.05) and apex (T4-T5: right; 118.8 ± 1.2 ms, left; 114.6 ± 2.6 ms. P < 0.05), greater shortening of effective refractory period (T4-T5: right; -3.6 ± 1.3%, left; -7.7 ± 1.8%. P < 0.05), a steeper maximum slope of restitution (T4-T5 base: right; 1.3 ± 0.2, left; 1.8 ± 0.2. P < 0.01. T4-T5 apex: right; 1.0 ± 0.2, left; 1.6 ± 0.3. P < 0.05) and a greater decrease in ventricular fibrillation threshold (T4-T5: right; -22.3 ± 6.8%, left;-39.0 ± 1.7%), with dominant effects at caudal levels (T4-T6).

CONCLUSIONS

The preganglionic sympathetic efferent axons show functionally distinct pathways to the heart. The caudal segments (T4-T6) of the left sympathetic chain had a greater potential for arrhythmia generation and hence could pose a target for more focused clinical treatments for impairments in cardiac function.

Minimally invasive transtracheal cardiac plexus block for sympathetic neuromodulation

BACKGROUND

Bilateral thoracoscopic stellectomy has antiarrhythmic effects, but the procedure is invasive with associated morbidity. Sympathetic nerves from both stellate ganglia form the deep cardiac plexus (CP) in the aortopulmonary window, anterior to the trachea.

OBJECTIVE

The purpose of this study was to demonstrate a novel and minimally invasive transtracheal approach to block the CP in porcine models.

METHODS

In 12 Yorkshire pigs, right (RSG) and left (LSG) stellate ganglia were electrically stimulated and sympathetic baseline response recorded (hemodynamic parameters and T-wave pattern). Aortopulmonary window was accessed transtracheally with endobronchial ultrasound guidance, and local stimulation of CP confirmed the location. Injection of 1% lidocaine (n = 10) or saline solution (n = 2) was performed, and RSG and LSG responses were re-evaluated and compared with baseline.

RESULTS

Transtracheal lidocaine injection into the CP successfully blocked bilateral sympathetic induced changes (%) in T-wave amplitude (282.8% ± 152.2% vs 20.1% ± 16.5%; P <.001 [LSG]; 338.9% ± 189.8% vs 28% ± 18.3%; P <.001 [RSG]), Tp-Te interval (87.9% ± 37.2% vs 6.9% ± 6.7%; P <.001 [LSG]; 32.6% ± 27.4% vs 6.9% ± 4.7%; P <.035 [RSG]), and left ventricular dP/dT_max (148.3% ± 108.5% vs 16.5% ± 13.4%; P <.001 [LSG]; 243.1% ± 105.2% vs 19.0% ± 12.4%; P <.001 [RSG]). RSG-induced elevations of systemic, left ventricular, and pulmonary arterial pressures were blocked by lidocaine injection into CP (P <.005 for all comparisons). Stellate ganglia response was not affected in sham studies. No complications were observed during the procedures.

CONCLUSION

Minimally invasive transtracheal injection of lidocaine into the CP blocked the sympathetic response of either RSG and LSG. Transtracheal assessment of CP may allow for minimally invasive and selective ablation of cardiac innervation, extending the cardiac sympathectomy denervation benefits to those not suitable for surgery.

Substrates and potential therapeutics of ventricular arrhythmias in heart failure

Heart failure (HF) is a clinical syndrome characterized by ventricular contractile dysfunction. About 50% of death in patients with HF are due to fetal ventricular arrhythmias including ventricular tachycardia and ventricular fibrillation. Understanding ventricular arrhythmic substrates and discovering effective antiarrhythmic interventions are extremely important for improving the prognosis of patients with HF and reducing its mortality. In this review, we discussed ventricular arrhythmic substrates and current clinical therapeutics for ventricular arrhythmias in HF. Base on the fact that classic antiarrhythmic drugs have the limited efficacy, side effects, and proarrhythmic potentials, we also updated some therapeutic strategies for the development of potential new antiarrhythmic interventions for patients with HF.

Effectiveness of stellate ganglion blockade on refractory ventricular arrhythmias: a systematic review protocol

REVIEW QUESTION

The question of this review is: what is the effectiveness of stellate ganglion blockade on refractory ventricular arrhythmias in patients 18 years or over?

Catheter Ablation for Ventricular Tachycardia in Patients with Structural Heart Disease

Ventricular tachycardia is a potentially fatal arrhythmia that occurs most frequently in patients with structural heart disease. Acute and long- term management can be complex, requiring an integrated approach with multiple therapeutic modalities including antiarrhythmic drugs, implantable cardioverter defibrillators, and catheter ablation. Each of these options has a role in management of ventricular tachycardia and are generally used in combination. It is essential to be aware that each approach has potential deleterious consequences that must be balanced while establishing a treatment strategy. Catheter ablation for ventricular tachycardia is performed with increasing frequency with rapidly evolving techniques. In this review, we discuss the acute and long-term management of ventricular tachycardia with a focus on techniques and evidence for catheter ablation.

Mechanisms and management of refractory ventricular arrhythmias in the age of autonomic modulation

Ventricular arrhythmias are responsible for hundreds of thousands of deaths every year. Catheter ablation of ventricular tachycardia (VT) is an essential component of the management of these life-threatening arrhythmias. However, in many patients, despite medical and interventional therapy, VT recurs. Furthermore, some VT substrates (mid-myocardial, left ventricular summit, and intraseptal) are not easily targeted because of limitations of currently available technology. In certain clinical settings, ventricular fibrillation (VF) episodes that have premature ventricular contraction triggers can also be targeted with catheter ablation. However, in most patients there is no clear VF trigger to target, and therefore polymorphic VT or VF cannot be adequately treated with catheter ablation. The autonomic nervous system plays a crucial role in all aspects of ventricular arrhythmias, yet interventions specific to the cardiac neuronal axis have been largely underutilized. This underutilization has been most pronounced in patients with structural heart disease. However, there is a growing body of literature on the physiology and pathophysiology of cardiac neural control and the benefits of neuromodulation to treat refractory ventricular arrhythmias in these patients. We present case-based examples of neuromodulatory interventions currently available and a review of the literature supporting their use.

Team Management of the Ventricular Tachycardia Patient

Ventricular tachycardia is a common arrhythmia in patients with structural heart disease and heart failure, and is now seen more frequently as these patients survive longer with modern therapies. In addition, these patients often have multiple comorbidities. While anti-arrhythmic drug therapy, implantable cardioverter-defibrillator implantation and ventricular tachycardia ablation are the mainstay of therapy, well managed by the cardiac electrophysiologist, there are many other facets in the care of these patients, such as heart failure management, treatment of comorbidities and anaesthetic interventions, where the expertise of other specialists is essential for optimal patient care. A coordinated team approach is therefore essential to achieve the best possible outcomes for these complex patients.

Cardiac Innervation and the Autonomic Nervous System in Sudden Cardiac Death

Neural remodeling in the autonomic nervous system contributes to sudden cardiac death. The fabric of cardiac excitability and propagation is controlled by autonomic innervation. Heart disease predisposes to malignant ventricular arrhythmias by causing neural remodeling at the level of the myocardium, the intrinsic cardiac ganglia, extracardiac intrathoracic sympathetic ganglia, extrathoracic ganglia, spinal cord, and the brainstem, as well as the higher centers and the cortex. Therapeutic strategies at each of these levels aim to restore the balance between the sympathetic and parasympathetic branches. Understanding this complex neural network will provide important therapeutic insights into the treatment of sudden cardiac death.

Thoracic Epidural Anesthesia Can Be Effective for the Short-Term Management of Ventricular Tachycardia Storm

Background

Novel therapies aimed at modulating the autonomic nervous system, including thoracic epidural anesthesia (TEA), have been shown in small case series to be beneficial in treating medically refractory ventricular tachycardia (VT) storm. However, it is not clear when these options should be considered. We reviewed a multicenter experience with TEA in the management of VT storm to determine its optimal therapeutic use.

Methods and Results

Data for 11 patients in whom TEA was instituted for VT storm between July 2005 and March 2016 were reviewed to determine the clinical characteristics, outcomes, and role in management. The clinical presentation was incessant VT in 7 (64%), with polymorphic VT in 3 (27%) and monomorphic VT in 8 (73%). The underlying conditions were nonischemic cardiomyopathy in 5 (45%), ischemic cardiomyopathy in 3 (27%), and hypertrophic cardiomyopathy, Brugada syndrome, and cardiac lipoma in 1 (9%) each. Five (45%) had a complete and 1 (9%) had a partial response to TEA; 4 of the complete responders had incessant VT. All 4 patients with a documented response to deep sedation demonstrated a complete response to TEA.

Conclusions

More than half of the patients with VT storm in our series responded to TEA. TEA may be effective and should be considered as a therapeutic option in patients with VT storm, especially incessant VT, who are refractory to initial management. Improvement in VT burden with deep sedation may suggest that sympathoexcitation plays a key role in perpetuating VT and predict a positive response to TEA.

Sudden death: Neurogenic causes, prediction and prevention

Sudden death is a major health problem all over the world. The most common causes of sudden death are cardiac but there are also other causes such as neurological conditions (stroke, epileptic attacks and brain trauma), drugs, catecholamine toxicity, etc. A common feature of all these diverse pathologies underlying sudden death is the imbalance of the autonomic nervous system control of the cardiovascular system. This paper reviews different pathologies underlying sudden death with emphasis on the autonomic nervous system contribution, possibilities of early diagnosis and prognosis of sudden death using various clinical markers including autonomic markers (heart rate variability and baroreflex sensitivity), present possibilities of management and promising prevention by electrical neuromodulation.

Electrical Storm in Patients with Implantable Cardioverter-defibrillators: A Practical Overview

Electrical storm (ES) is an increasingly common medical emergency characterized by clustered episodes of sustained ventricular arrhythmias (VAs) that lead to repeated appropriate implantable cardioverter-defibrillator (ICD) therapies. A diagnosis of ES can be made with the occurrence of three or more sustained episodes of VAs, or of three or more appropriate ICD therapies within 24 hours in patients with implanted devices. ES is associated with poor outcomes in patients with structural heart disease, particularly those with severe left ventricular dysfunction. In large clinical trials involving patients with ICDs for primary and secondary prevention, ES appears to be a predictor of cardiac death, with notably higher rates of mortality soon after the event. ES management is challenging and requires special medical attention with accurate patient risk stratification and a multidisciplinary approach that includes the use of pharmacologic therapies such as antiarrhythmic drugs (AADs) and interventional approaches like catheter ablation, surgical ablation, or sympathetic neuromodulation. Initial management involves determining and addressing the underlying ischemia, any electrolyte imbalances, and/or other causative factors. Hemodynamic support needs to be considered in high-risk patients with unstable VAs or those with severe comorbidities such as low left ventricular ejection fraction, advanced New York Heart Association class, and/or chronic pulmonary disease. Following the acute phase of ES, treatment should shift towards maximizing therapeutic efforts to address heart failure, performing revascularization, and preventing subsequent VAs. In the present manuscript, we offer an overview of the most relevant clinical aspects of ES with regard to novel therapeutic strategies.

Inflammation, oxidative stress, and glial cell activation characterize stellate ganglia from humans with electrical storm

BACKGROUND

Neuronal remodeling in human heart disease is not well understood.

METHODS

Stellate ganglia from patients with cardiomyopathy (CMY) and refractory ventricular arrhythmias undergoing cardiac sympathetic denervation (n = 8), and from organ donors with normal hearts (n = 8) collected at the time of organ procurement were compared. Clinical data on all subjects were reviewed. Electron microscopy (EM), histologic, and immunohistochemical assessments of neurotransmitter profiles, glial activation and distribution, and lipofuscin deposition, a marker of oxidative stress, were quantified.

RESULTS

In CMY specimens, lipofuscin deposits were larger, and present in more neurons (26.3% ± 6.3% vs. 16.7% ± 7.6%, P < 0.043), than age-matched controls. EM analysis revealed extensive mitochondrial degeneration in CMY specimens. T cell (CD3+) infiltration was identified in 60% of the CMY samples, with one case having large inflammatory nodules, while none were identified in controls. Myeloperoxidase-immunoreactive neutrophils were also identified at parenchymal sites distinct from inflammatory foci in CMY ganglia, but not in controls. The adrenergic phenotype of pathologic samples revealed a decrease in tyrosine hydroxylase staining intensity compared with controls. Evaluation of cholinergic phenotype by staining for the vesicular acetylcholine transporter revealed a low but comparable number of cholinergic neurons in ganglia from both groups and demonstrated that preganglionic cholinergic innervation was maintained in CMY ganglia. S100 staining (a glial cell marker) demonstrated no differences in glial distribution and relationship to neurons; however, glial activation demonstrated by glial fibrillary acidic protein (GFAP) staining was substantially increased in pathologic specimens compared with controls.

CONCLUSIONS

Stellate ganglia from patients with CMY and arrhythmias demonstrate inflammation, neurochemical remodeling, oxidative stress, and satellite glial cell activation. These changes likely contribute to excessive and dysfunctional efferent sympathetic tone, and provide a rationale for sympathectomy as a treatment for arrhythmias in this population.

FUNDING

This work was made possible by support from NIH grants HL125730 to OAA, GM107949 to DBH, and HL084261 and OT2OD023848 to KS.

Bilateral sympathectomy for treatment of refractory ventricular tachycardia

Ventricular tachycardia (VT) commonly occurs in patients with ischemic or nonischemic cardiomyopathy and requires antiarrhythmic drugs, ablation, or advanced circulatory support. However, life-threatening VT may be refractory to these therapies, and may cause frequent implantable cardioverter defibrillator (ICD) discharges. Left cardiac sympathetic denervation reduces the occurrence of these fatal arrhythmias by inhibiting the sympathetic outflow to the cardiac tissue. We present a 69-year-old man with nonischemic cardiomyopathy, life-threatening VT, and hemodynamic instability with numerous ICD discharges, who remained refractory to antiarrhythmic drug therapy and ablation attempts. He was effectively treated with bilateral cardiac sympathectomy. Six months later, he remained free of VT with no ICD discharges.

Ventricular Tachycardia in Ischemic Heart Disease

Ventricular arrhythmias are a significant cause of morbidity and mortality in patients with ischemic structural heart disease. Endocardial and epicardial mapping strategies include scar characterization channel identification, and recording and ablation of late potentials and local abnormal ventricular activities. Catheter ablation along with new technology and techniques of bipolar ablation, needle catheter, and autonomic modulation may increase efficacy in difficult to ablate ventricular arrhythmias. Catheter ablation of ventricular arrhythmias seem to confer mortality and morbidity benefits in patients with ischemic heart disease.

Percutaneous extracorporeal membrane oxygenation in electrical storm: five case reports addressing efficacy, transferring allowance or radiofrequency ablation support

Extracorporeal membrane oxygenation systems have undergone rapid technological improvements and are now feasible options for medium-term support of severe cardiac or pulmonary failure. We report five cases of electrical storm that was rescued by the insertion of peripheral veno-arterial extracorporeal membrane oxygenation systems. This device could help to restore systemic circulation as well as permitting organ perfusion in patients with cardiogenic shock in relation to electrical storm thus achieving greater electrical stability. Also, in some cases extracorporeal membrane oxygenation support could facilitate electrophysiology study.

Cardiac Sympathetic Denervation for Refractory Ventricular Arrhythmias

BACKGROUND

Cardiac sympathetic denervation (CSD) has been shown to reduce the burden of implantable cardioverter-defibrillator (ICD) shocks in small series of patients with structural heart disease (SHD) and recurrent ventricular tachyarrhythmias (VT).

OBJECTIVES

This study assessed the value of CSD and the characteristics associated with outcomes in this population.

METHODS

Patients with SHD who underwent CSD for refractory VT or VT storm at 5 international centers were analyzed by the International Cardiac Sympathetic Denervation Collaborative Group. Kaplan-Meier analysis was used to estimate freedom from ICD shock, heart transplantation, and death. Cox proportional hazards models were used to analyze variables associated with ICD shock recurrence and mortality after CSD.

RESULTS

Between 2009 and 2016, 121 patients (age 55 ± 13 years, 26% female, mean ejection fraction of 30 ± 13%) underwent left or bilateral CSD. One-year freedom from sustained VT/ICD shock and ICD shock, transplant, and death were 58% and 50%, respectively. CSD reduced the burden of ICD shocks from a mean of 18 ± 30 (median 10) in the year before study entry to 2.0 ± 4.3 (median 0) at a median follow-up of 1.1 years (p < 0.01). On multivariable analysis, pre-procedure New York Heart Association functional class III and IV heart failure and longer VT cycle lengths were associated with recurrent ICD shocks, whereas advanced New York Heart Association functional class, longer VT cycle lengths, and a left-sided-only procedure predicted the combined endpoint of sustained VT/ICD shock recurrence, death, and transplantation. Of the 120 patients taking antiarrhythmic medications before CSD, 39 (32%) no longer required them at follow-up.

CONCLUSIONS

CSD decreased sustained VT and ICD shock recurrence in patients with refractory VT. Characteristics independently associated with recurrence and mortality were advanced heart failure, VT cycle length, and a left-sided-only procedure.