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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy caused by defective desmosomal proteins. The typical histopathological finding of ARVC is characterized by progressive fibrofatty infiltration of the right ventricle due to the dysfunction of cellular adhesion molecules, thus, developing arrhythmogenic substrates responsible for the clinical manifestation of ventricular tachycardia/fibrillation (VT/VF). Current guidelines recommend implantable cardiac defibrillator (ICD) implantation to prevent sudden cardiac death (SCD) in ARVC, especially for those experiencing VT/VF or aborted SCD, while antiarrhythmic drugs, despite their modest effectiveness and several undesirable adverse effects, are frequently used for those experiencing episodes of ICD interventions. Given the advances in mapping and ablation technologies, catheter ablation has been implemented to eliminate drug-refractory VT in ARVC. A better understanding of the pathogenesis, underlying arrhythmogenic substrates, and putative VT isthmus in ARVC contributes to a significant improvement in ablation outcomes through comprehensive endocardial and epicardial approaches. Regardless of ablation strategies, there is a diversity of arrhythmogenic substrates in ARVC, which could partly explain the nonuniform ablation outcome and long-term recurrences and reflect the role of potential factors in the modification of disease progression and triggering of arrhythmic events.

Aims: J-wave syndrome in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) has been linked to an increased risk of ventricular arrhythmia. We investigated the significance of J waves with respect to substrate manifestations and ablation outcomes in patients with ARVC.Methods and Results: Forty-five patients with ARVC undergoing endocardial/epicardial mapping/ablation were studied. Patients were classified into two groups: 13 (28.9%) and 32 (71.1%) patients with and without J waves, respectively. The baseline characteristics, electrophysiological features, ventricular substrate, and recurrent ventricular tachycardia/fibrillation (VT/VF) were compared. Among the 13 patients with J waves, only the inferior J wave was observed. More ARVC patients with J waves fulfilled the major criteria of ventricular arrhythmias (76.9% vs. 21.9%, P = 0.003). Similar endocardial and epicardial substrate characteristics were observed between the two groups. However, patients with J waves had longer epicardial total activation time than those without (224.7 ± 29.9 vs. 200.8 ± 21.9 ms, P = 0.005). Concordance of latest endo/epicardial activation sites was observed in 29 (90.6%) patients without J waves and in none among those with J waves (P < 0.001). Complete elimination of endocardial/epicardial abnormal potentials resulted in the disappearance of the J wave in 8 of 13 (61.5%) patients. The VT/VF recurrences were not different between ARVC patients with and without J waves.Conclusion: The presence of J waves was associated with the discordance of endocardial/epicardial activation pattern in terms of transmural depolarization discrepancy in patients with ARVC. [ABSTRACT FROM AUTHOR]

Background: Signal-averaged electrocardiogram (SAECG) provides not only diagnostic information but also the prognostic implication of ablation in arrhythmogenic right ventricular cardiomyopathy (ARVC).Objective: This study aimed to validate the role of SAECG in identifying arrhythmogenic substrates requiring an epicardial approach in ARVC.Methods: Ninety-one patients with a definite diagnosis of ARVC who underwent successful ablation for drug-refractory ventricular arrhythmia were enrolled and classified into 2 groups: group 1 who underwent successful ablation at the endocardium only and group 2 who underwent successful ablation requiring an additional epicardial approach. The baseline characteristics of patients and SAECG parameters were obtained for analysis.Results: Male predominance, worse right ventricular (RV) function, higher incidence of syncope, and depolarization abnormality were observed in group 2. Moreover, the number of abnormal SAECG criteria was higher in group 2 than in group 1. After a multivariate analysis, the independent predictors of the requirement of epicardial ablation included the number of abnormal SAECG criteria (odds ratio 2.8, 95% confidence interval 1.4-5.4; P = .003) and presence of syncope (odds ratio 11.7; 95% confidence interval 2.7-50.4; P = .001). In addition, ≥2 abnormal SAECG criteria were associated with larger RV endocardial unipolar low-voltage zone (P < .001), larger RV endocardial/epicardial bipolar low-voltage zone/scar (P < .05), and longer RV endocardial/epicardial total activation time (P < .001 and P = .004, respectively).Conclusion: The number of abnormal SAECG criteria was correlated with the extent of diseased epicardial substrates and could be a potential surrogate marker for predicting the requirement of epicardial ablation in patients with ARVC. [ABSTRACT FROM AUTHOR]

The article presents a case study 63‐year‐old man with right ventricular cardiomyopathy (ARVC) and paroxysmal atrial fibrillation presented with cardiac arrest with pulseless ventricular tachycardia. It mentions that endocardial ablation can reduce the epicardial radiofrequency energy delivery required, which has potential complications, including phrenic nerve injury; and also mentions that Endocardial ablation of epicardial . Local abnormal ventricular activity is feasible in ARVC.

Abstract: Background: During epicardial mapping, determination of appropriate ablation sites in low voltage areas (LVA) is challenging because of large epicardial areas covered by adipose tissue. Objective: To evaluate the impedance difference between epicardial fat and the epicardial LVA using multiple detector computed tomography (MDCT). Methods: We enrolled patients who underwent ventricular tachycardia (VT) ablation via the epicardial approach after endocardial ablation failure. After the procedure, MDCT‐derived images of epicardial fat were loaded to the mapping system. Then, all points acquired during sinus rhythm were retrospectively superimposed and analyzed. Results: This study included data from 7 patients (62.5 ± 3.9 years old) who underwent eight epicardial VT ablation procedures. After the procedure, MDCT‐derived images of epicardial fat were registered in eight procedures. Retrospective analysis of 1,595 mapping and 236 ablation points was performed. Of the 1,595 mapping points on the merged electroanatomical and epicardial fat maps, normal voltage area (NVA) and low voltage area (LVA) without fat had lower impedance than those with fat (NVA without fat 182 ± 46 Ω vs. NVA with fat 321 ± 164.0 Ω, P  =  0.001, LVA without fat 164 ± 69 Ω vs. LVA with fat 248 ± 89 Ω, P  =  0.002). Of the 236 ablation points, initial impedance before ablation was higher on epicardial fat than on epicardial LVA without fat (134 ± 16 Ω vs. 156 ± 28 Ω, P  =  0.01). Conclusions: Real time epicardial impedance evaluation may be useful to determine effective epicardial ablation sites and avoid adipose tissue. However, the number of patients in the present study is limited. Further investigation with a large number of patients is needed to confirm our result. [ABSTRACT FROM AUTHOR]

Ventricular tachycardia (VT) occurring late after myocardial infarction is often due to reentry circuit in the peri-infarct zone. The circuit is usually located in the sub-endocardium, though subepicardial substrates are known. Activation mapping during VT to identify target regions for ablation can be difficult if VT is non inducible or poorly tolerated. In the latter, a substrate based approach of mapping during sinus rhythm in conjunction with pace mapping helps to define the reentry circuit and select target sites for ablation in majority of patients with hemodynamically unstable VT. Percutaneous epicardial catheter ablation has been attempted as an approach where ablation by a conventional endocardial access has been unsuccessful. We report a case of post myocardial infarction scar VT which could be successfully ablated with a substrate based approach from the epicardial aspect.

Background: There is no consensus on the appropriate indications for the epicardial approach in substrate ablation of post-myocardial infarction (MI) ventricular tachycardia (VT).Objective: The purpose of this study was to investigate whether infarct transmurality (IT) could identify patients who would benefit from a combined first-line endo-epicardial approach.Methods: Before ablation, IT was assessed by contrast-enhanced cardiac magnetic resonance imaging (hyperenhancement ≥75% of the wall thickness in ≥1 segment), echocardiography (dyskinesia/akinesia + hyperrefringency + wall thinning), computed tomography (wall thinning), or scintigraphy (transmural necrosis). Prospectively from January 2011, an endocardial approach was used in patients with subendocardial MI (group 1) and a combined endo-epicardial approach in patients with transmural MI (group 2). Outcomes in both groups were compared with those in patients with transmural MI and only endocardial approach due to previous cardiac surgery or procedure performed before January 2011 (group 3). The primary end point was VT/ventricular fibrillation recurrence-free survival.Results: Ninety patients (92.2% men; mean age 67.4 ± 9.8 years) undergoing VT substrate ablation were included: group 1, n = 34; group 2, n = 24; group 3, n = 32. During a mean follow-up duration of 22.5 ± 13.7 months, 5 patients in group 1 (14.7%), 3 patients in group 2 (12.5%), and 13 patients in group 3 (40.6%) had VT recurrences (P = .011). Time to recurrence was the shortest in group 3 (log-rank, P = .018). The endocardial approach in patients with transmural MI was associated with an increased risk of recurrence (hazard ratio 4.01; 95% confidence interval 1.41-11.3; P = .009).Conclusion: The endocardial approach in patients with transmural MI undergoing VT substrate ablation is associated with an increased risk of recurrence. IT may be a useful criterion for the selection of a first-line combined endo-epicardial approach. [ABSTRACT FROM AUTHOR]

Background Right bundle branch block (RBBB) with superior axis electrocardiographic (ECG) morphology is common in patients with idiopathic ventricular arrhythmia (VA) originating from the left posterior fascicle (LPF), from the left ventricular (LV) posterior papillary muscles (PPM), and rarely from the cardiac apical crux. Objective The purpose of this study was to describe the ECG and clinical characteristics of idiopathic VA presenting with RBBB and superior axis. Methods We studied 40 patients who underwent successful catheter ablation of idiopathic VAs originating from the LPF (n = 18), LV PPM (n = 15), and apical crux (n = 7). We investigated clinical and ECG characteristics, including maximum deflection index and QRS morphology in leads aVR and V 6 . Results Syncope was more frequently seen in apical crux VA compared with other VAs (57% vs 6%, P < .001). Patients with apical crux VA more frequently had an maximum deflection index ≥0.55 compared with LPF VA and PPM VA ( P = .02). A monophasic R wave in aVR and QS or r/S ratio <0.15 in V 6 ( P < .001) could distinguish apical crux VA from other VAs with high accuracy. All patients with VA underwent attempted ablation in the endocardium (success rate: LPF 89%, PPM 80%, crux 14%). Only 1 of 7 patients with apical crux VA had acute success with ablation in the middle cardiac vein. In 2 of apical crux patients, epicardial ablation using subxiphoid approach was performed successfully. Conclusion We could distinguish LPF VA, PPM VA, and apical crux VA using a combination of clinical and ECG characteristics. These findings might be useful for counseling patients and planning an ablation strategy. [ABSTRACT FROM AUTHOR]

Subxiphoid puncture is considered the standard approach for epicardial ablation of ventricular arrhythmia, but in some cases this access is impracticable due to the patient's anatomy. We describe the case of a patient with electrical storm and abnormal subdiaphragmatic anatomy that precluded the usual subxiphoid approach. In this patient the pericardial space was gained through a direct thorax puncture at the fifth intercostals space close to the mammary line. The tools and technique utilized in this case were similar to what is usually used for traditional subxiphoid puncture. The thorax percutaneous puncture was successfully carried out without complication. [ABSTRACT FROM AUTHOR]

Gene therapy appears promising as a targeted treatment of cardiac diseases. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and also a major contributor to stroke, heart failure, and death. Mechanisms that initiate and sustain AF are associated with structural and electrophysiological remodeling in the whole atria. Selection of the appropriate gene delivery method is critical for transduction efficacy. The ideal gene delivery method to manage AF should provide widespread and sufficient exposure to the transgene in atria only that safely maintains the homeostasis of the heart without off-target expression. All these requirements can be achieved using atrial gene painting that is directly applied to the atrial epicardial surface. In this chapter, we present the advantages of atrial gene painting and the experimental method, as applied to a large animal model of AF., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Aims: J-wave syndrome in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) has been linked to an increased risk of ventricular arrhythmia. We investigated the significance of J waves with respect to substrate manifestations and ablation outcomes in patients with ARVC., Methods and Results: Forty-five patients with ARVC undergoing endocardial/epicardial mapping/ablation were studied. Patients were classified into two groups: 13 (28.9%) and 32 (71.1%) patients with and without J waves, respectively. The baseline characteristics, electrophysiological features, ventricular substrate, and recurrent ventricular tachycardia/fibrillation (VT/VF) were compared. Among the 13 patients with J waves, only the inferior J wave was observed. More ARVC patients with J waves fulfilled the major criteria of ventricular arrhythmias (76.9% vs. 21.9%, P = 0.003). Similar endocardial and epicardial substrate characteristics were observed between the two groups. However, patients with J waves had longer epicardial total activation time than those without (224.7 ± 29.9 vs. 200.8 ± 21.9 ms, P = 0.005). Concordance of latest endo/epicardial activation sites was observed in 29 (90.6%) patients without J waves and in none among those with J waves (P < 0.001). Complete elimination of endocardial/epicardial abnormal potentials resulted in the disappearance of the J wave in 8 of 13 (61.5%) patients. The VT/VF recurrences were not different between ARVC patients with and without J waves., Conclusion: The presence of J waves was associated with the discordance of endocardial/epicardial activation pattern in terms of transmural depolarization discrepancy in patients with ARVC., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

The percutaneous epicardial approach has become an adjunctive tool for electrophysiologists to treat disparate cardiac arrhythmias, including accessory pathways, atrial tachycardia, and particularly ventricular tachycardia. This novel technique prompted a strong impulse to perform epicardial access as an alternative strategy for pacing and defibrillation, left atrial appendage exclusion, heart failure with preserved ejection fraction, and genetically engineered tissue delivery. However, because of the incremental risk of major complications compared with stand-alone endocardial ablation, it is still practiced in a limited number of highly experienced centers across the world., Competing Interests: Conflicts of interest Dr J.D. Burkhardt is a consultant for Biosense Webster and Stereotaxis. Dr A. Natale has received speaker honoraria from Boston Scientific, Biosense Webster, St. Jude Medical, Biotronik, and Medtronic; and is a consultant for Biosense Webster, St. Jude Medical, and Janssen. All other authors have reported that they have no relationships relevant to the contents of this article to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Gene therapy holds great promise as a targeted treatment of cardiovascular diseases, which remain a major cause of morbidity and mortality in contemporary societies. Selection of the appropriate vector delivery method is critical for efficient transduction in the myocardium. Direct myocardial delivery is a feasible and effective method that has been shown to exhibit enhanced gene expression compared to coronary infusion and pericardial delivery. It is one of the most widely used gene transfer methods in both animal studies and clinical trials. The advantages, which result from a delivery that avoids exposure to the blood and bypasses the endothelial barrier, are a high local concentration at the injection site and a decreased leakage to off-target organs. The vectors are injected either with an endomyocardial or an epicardial approach, either surgically or percutaneously. In this chapter, we present the different approaches of direct myocardial injection, their advantages and their realization method in preclinical large animal models of cardiovascular diseases.

Aims The aim of this study is to evaluate the benefit of manually controlled steerable sheath, which provides greater flexibility and stability, in mapping and ablation procedure of ventricular tachycardia. Methods and results We retrospectively reviewed 40 patients who underwent epicardial mapping and conclusive ablation. The first attempt to reach the primary endpoint defined as successful creation of detailed map of entire epicardial space and was achieved in 16 patients. Among the remaining 24 patients, we used the steerable sheath and achieved further success to create an entire map in all patients. After the delivery of RF energy, final procedural success was defined as complete abolishment of late potential and no more induction of any VT, and that was obtained in 10 out of 16 patients mapped with conventional sheath and 21 out of 24 patients with steerable sheath. The advantage of the steerable sheath seemed to be consistent, regardless of the site of ablation. There was no procedure-related adverse event. Conclusions The manually controlled steerable sheath was safe and effective to achieve procedural success in patients with epicardial VT. [ABSTRACT FROM PUBLISHER]

Ventricular tachycardia (VT) occurring late after myocardial infarction is often due to reentry circuit in the peri-infarct zone. The circuit is usually located in the sub-endocardium, though subepicardial substrates are known. Activation mapping during VT to identify target regions for ablation can be difficult if VT is non inducible or poorly tolerated. In the latter, a substrate based approach of mapping during sinus rhythm in conjunction with pace mapping helps to define the reentry circuit and select target sites for ablation in majority of patients with hemodynamically unstable VT. Percutaneous epicardial catheter ablation has been attempted as an approach where ablation by a conventional endocardial access has been unsuccessful. We report a case of post myocardial infarction scar VT which could be successfully ablated with a substrate based approach from the epicardial aspect.