Cardiac sympathectomy for refractory ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy

Heterozygous desmoplakin (DSP) variants presenting with early onset cardiomyopathy and refractory ventricular tachycardia

Arrhythmogenic cardiomyopathy is a non-ischaemic cardiomyopathy characterised by the presence of myocardial dysfunction and inherited conduction disease that predisposes patients to malignant ventricular arrhythmias and sudden cardiac death. There is a growing awareness of the diverse phenotypic presentation of arrhythmogenic cardiomyopathy, which may demonstrate preferential involvement of the left, right or both ventricles. A subset of arrhythmogenic cardiomyopathy may be due to mutations of desmosomes, intercellular junctions of the myocardium that promote structural and electrical integrity. Mutations of desmoplakin, encoded by the DSP gene and a critical constituent protein of desmosomes, have been implicated in the onset of arrhythmogenic cardiomyopathy. We present a structured case report of desmoplakin arrhythmogenic cardiomyopathy secondary to novel heterozygous DSP mutations (c.1061T>C and c.795G>C) manifesting as early onset non-ischaemic cardiomyopathy and recurrent ventricular tachycardia refractory to multiple modalities of therapy, including oral antiarrhythmics, cardiac ablation and bilateral sympathectomy, as well as frequent implantable cardioverter-defibrillator discharges.

Bilateral Cardiac Sympathetic Denervation as a Safe Therapeutic Option for Ventricular Arrhythmias

Background

The recurrence of ventricular arrhythmias (VAs) in patients who have already undergone treatment with antiarrhythmic medication, catheter ablation, and the insertion of implantable cardioverter defibrillators is not uncommon. Recent studies have shown that bilateral cardiac sympathetic denervation (BCSD) effectively treats VAs. However, only a limited number of studies have confirmed the safety of BCSD as a viable therapeutic option for VAs.

Methods

This single-center study included 10 patients, who had a median age of 54 years (interquartile range [IQR], 45-65 years) and a median ejection fraction of 58.5% (IQR, 56.2%-60.8%), with VAs who underwent video-assisted BCSD. BCSD was executed as a single-stage surgery for 8 patients, while the remaining 2 patients initially underwent left cardiac sympathetic denervation followed by right cardiac sympathetic denervation. We evaluated postoperative complications, the duration of hospital stays, and VA-related symptoms before and after surgery.

Results

The median hospital stay after surgery was 2 days (IQR, 2-3 days). The median surgical time for BCSD was 113 minutes (IQR, 104-126 minutes). No significant complications occurred during hospitalization or after discharge. During the median follow-up period of 13.5 months (IQR, 10.5-28.0 months) from surgery, no VA-related symptoms were observed in 70% of patients.

Conclusion

The benefits of a short postoperative hospitalization and negligible complications make BCSD a safe, alternative therapeutic option for patients suffering from refractory VAs.

Prevention of Sudden Death and Management of Ventricular Arrhythmias in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy is an umbrella term for a group of inherited diseases of the cardiac muscle characterized by progressive fibro-fatty replacement of the myocardium. As suggested by the name, the disease confers electrical instability to the heart and increases the risk of the development of life-threatening arrhythmias, representing one of the leading causes of sudden cardiac death (SCD), especially in young athletes. In this review, the authors review the current knowledge of the disease, highlighting the state-of-the-art approaches to the prevention of the occurrence of SCD.

Artemisinin attenuates type 2 diabetic cardiomyopathy in rats through modulation of AGE-RAGE/HMGB-1 signaling pathway

Diabetes mellitus is a common metabolic disorder. About two-thirds of diabetic patients develop diabetic cardiomyopathy (DCM), which becomes a challenging issue as it severely threatens the patient's life. Hyperglycemia and the resulting advanced glycated end products (AGE) and their receptor (RAGE)/High Mobility Group Box-1 (HMGB-1) molecular pathway are thought to be key players. Recently, artemisinin (ART) has gained more attention owing to its potent biological activities beyond its antimalarial effect. Herein, we aim to evaluate the effect of ART on DCM and the possible underlying mechanisms. Twenty-four male Sprague-Dawley rats were divided into: control, ART, type 2 diabetic and type 2 diabetic treated with ART groups. At the end of the research, the ECG was recorded, then the heart weight to body weight (HW/BW) ratio, fasting blood glucose, serum insulin and HOMA-IR were evaluated. Cardiac biomarkers (CK-MB and LDH), oxidative stress markers, IL-1β, AGE, RAGE and HMGB-1 expression were also measured. The heart specimens were stained for H&E as well as Masson's trichrome. DCM induced disturbances in all studied parameters; contrary to this, ART improved these insults. Our study concluded that ART could improve DCM through modulation of the AGE-RAGE/HMGB-1 signaling pathway, with subsequent impacts on oxidative stress, inflammation and fibrosis. ART could therefore be a promising therapy for the management of DCM.

The intercalated disc: a unique organelle for electromechanical synchrony in cardiomyocytes

The intercalated disc (ID) is a highly specialized structure that connects cardiomyocytes via mechanical and electrical junctions. Although described in some detail by light microscopy in the 19th century, it was in 1966 that electron microscopy images showed that the ID represented apposing cell borders and provided detailed insight into the complex ID nanostructure. Since then, much has been learned about the ID and its molecular composition, and it has become evident that a large number of proteins, not all of them involved in direct cell-to-cell coupling via mechanical or gap junctions, reside at the ID. Furthermore, an increasing number of functional interactions between ID components are emerging, leading to the concept that the ID is not the sum of isolated molecular silos but an interacting molecular complex, an "organelle" where components work in concert to bring about electrical and mechanical synchrony. The aim of the present review is to give a short historical account of the ID's discovery and an updated overview of its composition and organization, followed by a discussion of the physiological implications of the ID architecture and the local intermolecular interactions. The latter will focus on both the importance of normal conduction of cardiac action potentials as well as the impact on the pathophysiology of arrhythmias.

Cardiac Sympathetic Denervation for the Management of Ventricular Arrhythmias

BACKGROUND

The autonomic nervous system contributes to the pathogenesis of ventricular arrhythmias (VA). Though anti-arrhythmic drug therapy and catheter ablation are the mainstay of management of VAs, success may be limited in patients with more refractory arrhythmias. Sympathetic modulation is increasingly recognized as a valuable adjunct tool for managing VAs in patients with structural heart disease and inherited arrhythmias.

RESULTS

In this review, we explore the role of the sympathetic nervous system and rationale for cardiac sympathetic denervation (CSD) in VAs and provide a disease-focused review of the utility of CSD for patients both with and without structural heart disease.

CONCLUSIONS

We conclude that CSD is a reasonable therapeutic option for patients with VA, both with and without structural heart disease. Though not curative, many studies have demonstrated a significant reduction in the burden of VAs for the majority of patients undergoing the procedure. However, in patients with unilateral CSD and subsequent VA recurrence, complete bilateral CSD may provide long-lasting reprieve from VA.

Impaired heart rate variability in patients with arrhythmogenic cardiomyopathy: A multicenter retrospective study in China

BACKGROUND

Cardiac sympathetic nerve system (SNS) might play an important role in arrhythmogenesis of arrhythmogenic cardiomyopathy (ACM). This study aims to assess the activity of cardiac SNS in ACM patients by heart rate variability (HRV), and to investigate its predictive value for sustained ventricular tachycardia (sVT).

METHODS

A total of 88 ACM patients and 65 sex- and age- matched healthy participants were enrolled. The time domain measures were used to evaluate the activity of cardiac SNS. An independent cohort with 48 ACM patients was as the validation cohort.

RESULTS

ACM patients had lower levels of standard deviation of all NN intervals (SDNN) [118.0 (90.3, 136.8) vs. 152.0 (132.5, 174.5) ms, p < 0.001] compared with healthy participants. Further analysis showed ACM patients with sVT had lower levels of SDNN than those without sVT (105.0 ± 28.1 vs. 131.8 ± 33.1 ms, p < 0.001). Multivariate logistic regression analysis showed SDNN was independently associated with sVT in ACM patients [odds ratio (OR) 0.59, 95% confidence interval (CI) (0.45-0.78), p < 0.001]. Receiver operating characteristics curve demonstrated SDNN had clinical values in predicting sVT in ACM patients [area under the curve (AUC) = 0.73, 95% CI (0.63-0.84), p < 0.001], which was verified in the validation cohort.

CONCLUSION

The present study suggests that HRV is impaired in patients with ACM, and the SDNN level has a moderate value in risk stratification for sVT in ACM patients. In addition, the finding might provide new target for the further management of ACM with integrated traditional Chinese and western medicine.

Implantable defibrillators in primary prevention of genetic arrhythmias. A shocking choice?

Many previously unexplained life-threatening ventricular arrhythmias and sudden cardiac deaths (SCDs) in young individuals are now recognized to be genetic in nature and are ascribed to a growing number of distinct inherited arrhythmogenic diseases. These include hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia (VT), and short QT syndrome. Because of their lower frequency compared to coronary disease, risk factors for SCD are not very precise in patients with inherited arrhythmogenic diseases. As randomized studies are generally non-feasible and may even be ethically unjustifiable, especially in the presence of effective therapies, the risk assessment of malignant arrhythmic events such as SCD, cardiac arrest due to ventricular fibrillation (VF), appropriate implantable cardioverter defibrillator (ICD) interventions, or ICD therapy on fast VT/VF to guide ICD implantation is based on observational data and expert consensus. In this document, we review risk factors for SCD and indications for ICD implantation and additional therapies. What emerges is that, allowing for some important differences between cardiomyopathies and channelopathies, there is a growing and disquieting trend to create, and then use, semi-automated systems (risk scores, risk calculators, and, to some extent, even guidelines) which then dictate therapeutic choices. Their common denominator is a tendency to favour ICD implantation, sometime with reason, sometime without it. This contrasts with the time-honoured approach of selecting, among the available therapies, the best option (ICDs included) based on the clinical judgement for the specific patient and after having assessed the protection provided by optimal medical treatment.

Exercise Causes Arrhythmogenic Remodeling of Intracellular Calcium Dynamics in Plakophilin-2-Deficient Hearts

BACKGROUND

Exercise training, and catecholaminergic stimulation, increase the incidence of arrhythmic events in patients affected with arrhythmogenic right ventricular cardiomyopathy correlated with plakophilin-2 (PKP2) mutations. Separate data show that reduced abundance of PKP2 leads to dysregulation of intracellular Ca2+ (Ca2+i) homeostasis. Here, we study the relation between excercise, catecholaminergic stimulation, Ca2+i homeostasis, and arrhythmogenesis in PKP2-deficient murine hearts.

METHODS

Experiments were performed in myocytes from a cardiomyocyte-specific, tamoxifen-activated, PKP2 knockout murine line (PKP2cKO). For training, mice underwent 75 minutes of treadmill running once per day, 5 days each week for 6 weeks. We used multiple approaches including imaging, high-resolution mass spectrometry, electrocardiography, and pharmacological challenges to study the functional properties of cells/hearts in vitro and in vivo.

RESULTS

In myocytes from PKP2cKO animals, training increased sarcoplasmic reticulum Ca2+ load, increased the frequency and amplitude of spontaneous ryanodine receptor (ryanodine receptor 2)-mediated Ca2+ release events (sparks), and changed the time course of sarcomeric shortening. Phosphoproteomics analysis revealed that training led to hyperphosphorylation of phospholamban in residues 16 and 17, suggesting a catecholaminergic component. Isoproterenol-induced increase in Ca2+i transient amplitude showed a differential response to β-adrenergic blockade that depended on the purported ability of the blockers to reach intracellular receptors. Additional experiments showed significant reduction of isoproterenol-induced Ca2+i sparks and ventricular arrhythmias in PKP2cKO hearts exposed to an experimental blocker of ryanodine receptor 2 channels.

CONCLUSIONS

Exercise disproportionately affects Ca2+i homeostasis in PKP2-deficient hearts in a manner facilitated by stimulation of intracellular β-adrenergic receptors and hyperphosphorylation of phospholamban. These cellular changes create a proarrhythmogenic state that can be mitigated by ryanodine receptor 2 blockade. Our data unveil an arrhythmogenic mechanism for exercise-induced or catecholaminergic life-threatening arrhythmias in the setting of PKP2 deficit. We suggest that membrane-permeable β-blockers are potentially more efficient for patients with arrhythmogenic right ventricular cardiomyopathy, highlight the potential for ryanodine receptor 2 channel blockers as treatment for the control of heart rhythm in the population at risk, and propose that PKP2-dependent and phospholamban-dependent arrhythmogenic right ventricular cardiomyopathy-related arrhythmias have a common mechanism.

Electrocardiographic and histopathological characterizations of diabetic cardiomyopathy in rats

Diabetes is a clinical condition that is associated with insulin deficiency and hyperglycemia. Cardiomyopathy, retinopathy, neuropathy, and nephropathy are well known complications of the elevated blood glucose. Diabetic cardiomyopathy is a clinical disorder that is associated with systolic and diastolic dysfunction along with cardiac fibrosis, inflammation, and elevated oxidative stress. In this study, diabetes was induced by intraperitoneal injection of streptozotocin (STZ) 50 mg/kg. We determined the plasma levels of cardiac troponin-T (cTnT) and creatinine kinase MB (CK-MB) by ELISA. Diabetic rats showed abnormal cardiac architecture and increased collagen production. Significant elevation in ST-segment, prolonged QRS, and QT-intervals and increased ventricular rate were detected. Additionally, diabetic rats showed a prolongation in P wave duration and atrial tachyarrhythmia was observed. Plasma levels of cTnT and CK-MB were elevated. In conclusion, these electrocardiographic changes (elevated ST-segment, prolonged QT interval, and QRS complex, and increased heart rate) along with histopathological changes and increased collagen formation could be markers for the development of diabetic cardiomyopathy in rats.

Bilateral Thoracoscopic Sympathectomy after Sternotomy for Left Ventricular Assist Device Insertion

Our case is a 73-year-old male with persistent ventricular tachycardia (VT) leading to recent syncopal episodes despite VT ablation and multiple stellate ganglion blocks, frequent hospital admissions, and acute on chronic congestive heart failure requiring intra-aortic balloon pump. The decision was made to proceed with left ventricular assist device placement and bilateral sympathectomies simultaneously. After performing the sternotomy and widely opening bilateral pleural spaces, the lower third of the stellate ganglia to the level of T4 was removed using a combination of the thoracoscope with the sternotomy incision. The use of thoracoscopy greatly assisted with visualization during the sympathectomy.

OUP accepted manuscript

Proper management of patients affected by genetic disorders causing life-threatening arrhythmias is important for several reasons, including even societal ones, given the predominantly young age of those affected. Incorrect management often has dire consequences, ranging from unnecessary psychologic damage for the patients whose life becomes too limited by the fear of sudden death to equally avoidable tragedies when the entire armamentarium of effective therapies is not fully utilized. In this review, we focus primarily on long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT) and deal specifically with the clinical impact of the most commonly used cardiac sympathetic denervation (CSD), namely left cardiac sympathetic denervation (LCSD). The two of us have used LCSD in the management of our patients with either LQTS or CPVT for a very long time and have been involved in ∼500 such interventions. It is on the basis of this personal and direct experience that we wish to share our views with clinical cardiologists and electrophysiologists, adult and paediatric, and with genetic cardiologists. We will begin by reviewing the history and rationale underlying sympathetic denervation therapy and will continue with a disease-specific intensification of therapy, and then with a discussion on how the impressive efficacy of LCSD should translate into guideline-directed therapy in both current and future guidelines, in order to upgrade the quality of care in the era of precision medicine.

Autonomic Testing Optimizes Therapy for Heart Failure and Related Cardiovascular Disorders

PURPOSE OF REVIEW

Cardiovascular autonomic control is an intricately balanced dynamic process. Autonomic dysfunction, regardless of origin, promotes and sustains the disease processes, including in patients with heart failure (HF). Autonomic control is mediated through the two autonomic branches: parasympathetic and sympathetic (P&S). HF is arguably the disease that stands to most benefit from P&S manipulation to reduce mortality risk. This review article briefly summarizes some of the more common types of autonomic dysfunction (AD) that are found in heart failure, suggests a mechanism by which AD may contribute to HF, reviews AD involvement in common HF co-morbidities (e.g., ventricular arrhythmias, AFib, hypertension, and Cardiovascular Autonomic Neuropathy), and summarizes possible therapy options for treating AD in HF.

RECENT FINDINGS

Autonomic assessment is important in diagnosing and treating CHF, and its possible co-morbidities. Autonomic assessment may also have importance in predicting which patients may be susceptible to sudden cardiac death. This is important since most CHF patients with sudden cardiac death have preserved left ventricular ejection fraction and better discriminators are needed. Many life-threatening cardiovascular disorders will require invasive testing for precise diagnoses and therapy planning when modulating the ANS is important. In cases of non-life-threatening disorders, non-invasive ANS testing techniques, especially those that individually assess both ANS branches simultaneously and independently, are sufficient to diagnose and treat serially.

Ventricular arrhythmia management in patients with genetic cardiomyopathies

Genetic cardiomyopathies are associated with increased risk for cardiac arrhythmias and sudden cardiac death. The management of ventricular arrhythmias (VAs) in patients with these conditions can be nuanced due to particular disease-based considerations, yet data specifically addressing management in these patients are limited. Here we describe the current evidence-based approach to the management of ventricular rhythm disorders in patients with genetic forms of cardiomyopathy, namely, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, left ventricular noncompaction, and Brugada syndrome, including recommendations from consensus guideline statements when available.

Arrhythmia Mechanism and Dynamics in a Humanized Mouse Model of Inherited Cardiomyopathy Caused by Phospholamban R14del Mutation

BACKGROUND

Arginine (Arg) 14 deletion (R14del) in the calcium regulatory protein phospholamban (hPLN^R14del) has been identified as a disease-causing mutation in patients with an inherited cardiomyopathy. Mechanisms underlying the early arrhythmogenic phenotype that predisposes carriers of this mutation to sudden death with no apparent structural remodeling remain unclear.

METHODS

To address this, we performed high spatiotemporal resolution optical mapping of intact hearts from adult knock-in mice harboring the human PLN^WT (wildtype [WT], n=12) or the heterozygous human PLN^R14del mutation (R14del, n=12) before and after ex vivo challenge with isoproterenol and rapid pacing.

RESULTS

Adverse electrophysiological remodeling was evident in the absence of significant structural or hemodynamic changes. R14del hearts exhibited increased arrhythmia susceptibility compared with wildtype. Underlying this susceptibility was preferential right ventricular action potential prolongation that was unresponsive to β-adrenergic stimulation. A steep repolarization gradient at the left ventricular/right ventricular interface provided the substrate for interventricular activation delays and ultimately local conduction block during rapid pacing. This was followed by the initiation of macroreentrant circuits supporting the onset of ventricular tachycardia. Once sustained, these circuits evolved into high-frequency rotors, which in their majority were pinned to the right ventricle. These rotors exhibited unique spatiotemporal dynamics that promoted their increased stability in R14del compared with wildtype hearts.

CONCLUSIONS

Our findings highlight the crucial role of primary electric remodeling caused by the hPLN^R14del mutation. These inherently arrhythmogenic features form the substrate for adrenergic-mediated VT at early stages of PLN^R14del induced cardiomyopathy.

Efficacy of catheter ablation for premature ventricular contractions in arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Premature ventricular contractions (PVCs) may be found in any stage of arrhythmogenic right ventricular cardiomyopathy (ARVC) and have been associated with the risk of sustained ventricular tachycardia (VT).

OBJECTIVE

To investigate the role of PVC ablation in ARVC patients.

METHODS

We studied consecutive ARVC patients who underwent PVC ablation due to symptomatic high PVC burden. Mean daily PVC burden and antiarrhythmic drug (AAD) use were assessed before and after the procedure. Complete long-term success was defined as more than 80% reduction in PVC burden off of membrane-active AADs.

RESULTS

Eight patients (37 ± 15 years; 4 males) underwent PVC ablation. The mean daily PVC burden before ablation ranged from 5.4% to 24.8%. A total of 7 (87.5%) patients underwent epicardial ablation. Complete acute elimination of PVCs was achieved in 4 (50%) patients (no complications). The mean daily PVC burden variation ranged from an 87% reduction to a 26% increase after the procedure. Over a median follow-up of 345 days (range: 182-3004 days), only one (12.5%) patient presented complete long-term success, and 6 (75%) patients either maintained or increased the need for Class I or Class III AADs. A total of 2 (25%) patients experienced sustained VT for the first time following the ablation procedure, requiring repeat ablation. No death or heart transplantation occurred.

CONCLUSION

PVC ablation was not associated with a consistent reduction of the PVC burden in ARVC patients with symptomatic, frequent PVCs. PVC ablation may be reserved for highly symptomatic patients who failed AADs. Additional investigation is required to improve the efficacy of PVC ablation in ARVC patients.

Surgical Cardiac Sympathetic Denervation for Ventricular Arrhythmias: A Systematic Review

Ventricular arrhythmias are potentially life-threatening disorders that are commonly treated with medications, catheter ablation and implantable cardioverter defibrillator (ICD). Adult patients who continue to be symptomatic, with frequent ventricular arrhythmia cardiac events or defibrillation from ICD despite medical treatment, are a challenging subgroup to manage. Surgical cardiac sympathetic denervation has emerged as a possible treatment option for people refractory to less invasive medical options. Recent treatment guidelines have recommendedcardiac sympathectomy for ventricular tachycardia (VT) or VT/fibrillation storm refractory to antiarrhythmic medications, long QT syndrome, and catecholaminergic polymorphic VT, with much of the data pertaining to pediatric literature. However, for the adult population, the disease indications, complications, and risks of cardiac sympathectomy are less understood, as are the most effective surgical cardiac denervation techniques for this patient demographic. This systematic review navigates available literature evaluating surgical denervation disease state indications, techniques, and sympathectomy risks for medically refractory ventricular arrhythmia in the adult patient population.

Long-Term Outcomes of Bilateral Cardiac Sympathetic Denervation for Refractory Ventricular Tachycardia

OBJECTIVES

This study sought to explore the long-term arrhythmic outcomes of bilateral cardiac sympathetic denervation (BCSD).

BACKGROUND

BCSD has been associated with improved arrhythmic outcomes in patients with refractory ventricular arrhythmias. However, whether BCSD antiarrhythmic effects are sustained long after the procedure is still uncertain.

METHODS

We included consecutive patients who underwent BCSD because of refractory ventricular tachycardia (VT) and had at least 18 months of follow-up. VT recurrence after BCSD was evaluated to assess arrhythmic outcomes. The occurrence of VT episodes within the first 12 weeks after the procedure was assessed to explore the impact of early VT recurrence on late arrhythmia-free survival.

RESULTS

Twenty patients (42 ± 16 years; 55% male) were included in the analysis. Nineteen (95%) patients had structural heart disease (left ventricular ejection fraction: 0.46 ± 0.14). Class I or class III drugs failed for all patients, and the mean number of VT ablation procedures was 2.5 ± 1.6. Over a mean follow-up of 1,300 ± 321 days (median: 1,276 days [Interquartile range (IQR): 1,181 to 1,480 days), 11 (55%) patients remained VT free after sympathectomy. Freedom from sustained VT or implantable cardioverter-defibrillator shock was 60% (95% confidence interval: 0.35 to 0.77) and 54.5% (95% confidence interval: 0.31 to 0.73) after BCSD at 1 and 4 years. Early VT recurrence was not associated with worse late arrhythmia-free survival rates.

CONCLUSIONS

BCSD was associated with longstanding antiarrhythmic effects in patients with refractory ventricular arrhythmias. The occurrence of VT episodes early after the procedure was not associated with worse late arrhythmic outcomes.

Cardioprotective role of GTS-21 by attenuating the TLR4/NF-κB pathway in streptozotocin-induced diabetic cardiomyopathy in rats

The cholinergic anti-inflammatory pathway (CAP) was investigated in a variety of inflammatory conditions and constitutes a valuable line in their treatment. In the current study, we investigated the anti-inflammatory effect of GTS-21 (GTS) as a partial selective α7 nicotinic acetylcholine receptor (α7-nAchR) agonist in diabetic cardiomyopathy model in rats. This mechanism was elaborated to study whether it could alleviate the electrocardiographic, histopathological, and molecular levels of Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB) pathway proteins. Diabetes was induced by the injection of streptozotocin (STZ) (50 mg/kg). Diabetic rats were treated with GTS (1 or 2 mg/kg/day), methyllycaconitine (MLA), a selective α7-nAchR antagonist (2 mg/kg/day) plus GTS (2 mg/kg/day), or the vehicle. All treatments were given by the intraperitoneal route. Ventricular rate and different electrocardiograph (ECG) anomalies were detected. Plasma levels of cardiac troponin T (cTnT) and creatine kinase MB (CK-MB) were measured by ELISA. Additionally, we elucidated the levels of several proteins involved in the TLR4/NF-κB pathway. Cardiac levels of TLR4 and phosphorylated protein kinase B (p-Akt) were detected by ELISA. The cardiac expression of myeloid differentiation primary response 88 (Myd88), tumor necrosis factor receptor-associated factor 6 (TRAF6), NF-κB, interleukin 1β (IL-1β), and active caspase-1 were evaluated by immunohistochemical staining. Finally, the cardiac levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) were determined by ELISA. Diabetic rats showed (i) ECG signs of cardiomyopathy such as significant ST segment elevations, prolonged QRS, QT intervals, and ventricular tachycardia; (ii) increased plasma levels of cTnT and CK-MB; (iii) increased expression of cardiac TLR4; (iv) elevated immunohistochemical expression of cardiac, Myd88, TRAF6, and NF-κB; (v) diminution in the cardiac expression of p-Akt; and (vi) adaptive increases in cardiac expression of TNF-α and IL-6. These effects were ameliorated in diabetic rats treated with both doses of GTS. Pretreatment with MLA did not completely reverse the ameliorative effect of GTS on cTnT, TRAF6, TNF-α, and IL-6, thereby reinforcing the presence of possible α7-nAchR-independent mechanisms. The activation of α7-nAchR with GTS offers a promising prophylactic strategy for diabetic cardiomyopathy by attenuating the TLR4/NF-κB pathway.

Outcome of a Modified Sympathicotomy for Cardiac Neuromodulation of Untreatable Ventricular Tachycardia

OBJECTIVES

This study aimed to describe the preliminary results of a modified sympathicotomy for cardiac sympathetic denervation (CSD), which may reduce the predictive risk and intraoperative surgical time of the procedure.

BACKGROUND

CSD, in patients with refractory ventricular tachycardia (VT), is comprehensively recognized as an important treatment option for patients with structural heart disease as well as congenital inherited arrhythmia syndrome.

METHODS

We consecutively enrolled 5 patients with refractory VT. Baseline demographic, medical, and surgical data as well as arrhythmia outcomes and procedural complications were evaluated.

RESULTS

A total of 5 patients (mean age: 67.4 years) were enrolled for the treatment of refractory VT with a modified CSD technique. In 3 of 5 patients, an overall reduction in VT burden (ranging from 75% to 100%) and VT number was observed after the CSD despite an in-hospital early recurrence.

CONCLUSIONS

A modified CSD (sympathicotomy T2-T5) with stellate ganglion sparing and the use of unipolar radiofrequency is feasible, effective, and safe in the setting of untreatable VT.

Epicardial Ablation of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by progressive fibrofatty replacement of the myocardium, right ventricular enlargement, and malignant ventricular arrhythmias. Ventricular tachycardia (VT) may be seen in all stages of the disease and is associated with sudden cardiac death. In patients who failed anti-arrhythmic medical therapy, catheter ablation has become an attractive therapeutic option to reduce VT burden and implantable cardioverter-defibrillator interventions. In this article, the authors aim to address the overall concepts of epicardial catheter ablation in ARVC, focusing on substrate characterization and ablation strategies.

Arrhythmogenic Cardiomyopathy: Molecular Insights for Improved Therapeutic Design

Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder characterized by structural and electrical cardiac abnormalities, including myocardial fibro-fatty replacement. Its pathological ventricular substrate predisposes subjects to an increased risk of sudden cardiac death (SCD). ACM is a notorious cause of SCD in young athletes, and exercise has been documented to accelerate its progression. Although the genetic culprits are not exclusively limited to the intercalated disc, the majority of ACM-linked variants reside within desmosomal genes and are transmitted via Mendelian inheritance patterns; however, penetrance is highly variable. Its natural history features an initial “concealed phase” that results in patients being vulnerable to malignant arrhythmias prior to the onset of structural changes. Lack of effective therapies that target its pathophysiology renders management of patients challenging due to its progressive nature, and has highlighted a critical need to improve our understanding of its underlying mechanistic basis. In vitro and in vivo studies have begun to unravel the molecular consequences associated with disease causing variants, including altered Wnt/β-catenin signaling. Characterization of ACM mouse models has facilitated the evaluation of new therapeutic approaches. Improved molecular insight into the condition promises to usher in novel forms of therapy that will lead to improved care at the clinical bedside.

Quantitative Approach to Fragmented QRS in Arrhythmogenic Cardiomyopathy: From Disease towards Asymptomatic Carriers of Pathogenic Variants

Fragmented QRS complexes (fQRS) are common in patients with arrhythmogenic cardiomyopathy (ACM). A new method of fQRS quantification may aid early disease detection in pathogenic variant carriers and assessment of prognosis in patients with early stage ACM. Patients with definite ACM (n = 221, 66%), carriers of a pathogenic ACM-associated variant without a definite ACM diagnosis (n = 57, 17%) and control subjects (n = 58, 17%) were included. Quantitative fQRS (Q-fQRS) was defined as the total amount of deflections in the QRS complex in all 12 electrocardiography (ECG) leads. Q-fQRS was scored by a single observer and reproducibility was determined by three independent observers. Q-fQRS count was feasible with acceptable intra- and inter-observer agreement. Q-fQRS count is significantly higher in patients with definite ACM (54 ± 15) and pathogenic variant carriers (55 ± 10) compared to controls (35 ± 5) (p < 0.001). In patients with ACM, Q-fQRS was not associated with sustained ventricular arrhythmia (p = 0.701) at baseline or during follow-up (p = 0.335). Both definite ACM patients and pathogenic variant carriers not fulfilling ACM diagnosis have a higher Q-fQRS than controls. This may indicate that increased Q-fQRS is an early sign of disease penetrance. In concealed and early stages of ACM the role of Q-fQRS for risk stratification is limited.