Bipolar ablation involving coronary venous system for refractory left ventricular summit arrhythmias

Endo-epicardial Transmural Lesion Formation Utilizing Multipolar Radiofrequency Ablation

BACKGROUND

Conventional unipolar radiofrequency catheter ablation (RFCA) is limited by maximal lesion depths that fail to eliminate VTs with deep mid-myocardial critical components. The use of multipolar mapping catheters as an active part of the ablation circuit may provide a solution to these limitations.

OBJECTIVE

To evaluate a novel endo-epicardial multipolar-RFCA technique for creating transmural lesions in an in-vivo porcine model.

METHODS

Two catheter configurations were evaluated: (1) standard bipolar configuration with a 3.5-mm irrigated-tip catheter paired with an 8-mm non-irrigated-tip catheter. (2) Multipolar configuration with a 3.5-mm irrigated-tip catheter paired with a multipolar mapping catheter. In both configurations, the 3.5-mm irrigated-tip catheter was positioned on the endocardial surface of the LV with the corresponding catheter positioned perpendicularly on the epicardial surface.

RESULTS

The study included 10 subjects with a total of 30 lesions created using 6 different sets of catheter configurations and ablation parameters. Histopathological analysis revealed an average lesion depth was 10.6 ± 3.1 mm (range: 5-17 mm), corresponding to a lesion depth/tissue thickness ratio of 93.5 ± 12%. 20 out of 30 lesions (67%) achieved transmurality. No safety complications such as steam pops, fistulas, perforations, or tamponades were observed.

CONCLUSION

Endo-epicardial multipolar radiofrequency ablation can be performed effectively and safely using a multipolar mapping catheter as the return electrode in the epicardial space. Lesions created were voluminous with a high degree of transmurality, with no complications related to the application of radiofrequency recorded. This catheter configuration may present a novel solution to rapidly identify and target ventricular arrhythmias arising from the mid-myocardium.

Temperature-controlled bipolar radiofrequency ablation: An ex vivo study for optimizing efficacy and safety parameters

BACKGROUND

Clear indicators for efficacy and safety of bipolar radiofrequency catheter ablation (BRFA) remain undefined.

OBJECTIVE

This study aimed to investigate predictive indicators of transmural lesion formation and steam pop in BRFA.

METHODS

In an ex vivo model, BRFA was performed with either the QDOT Micro or ThermoCool SmartTouch SF as the active catheter and the DiamondTemp ablation (DTA) as the return catheter. Predictors of transmural lesion formation and steam pop occurrence were investigated.

RESULTS

A total of 391 BRFA applications were conducted under various catheter tip and tissue contact configurations with interelectrode distance of 6-27 mm. The ablation index (AI) adjusted for interelectrode distance was effective in predicting transmural lesion formation, with AI increasing linearly as interelectrode distance increased. Logistic regression revealed that the coefficient for AI was -0.040 (standard error, 0.0067; 95% confidence interval, -0.053 to -0.027; P < .0001); for interelectrode distance, it was 2.2 (standard error, 0.35; 95% confidence interval, 1.5-2.9; P < .0001). The AI required to achieve transmural lesion formation was calculated as AI = 54 × interelectrode distance - 260. Steam pops on the active side occurred only during power-controlled BRFA and were absent with a 45°C cutoff. On the return side, steam pops occurred above 55°C. Higher DTA temperatures resulted in deeper cracks.

CONCLUSION

An AI adjusted for interelectrode distance strongly predicted transmural lesion formation. Temperature-controlled BRFA with a 45°C cutoff for the active catheter and 55°C for the return catheter may prevent steam pops. Furthermore, steam pops induced by higher electrode temperatures may result in the formation of deeper cracks.

Targeting Ventricular Arrhythmias in Non-Ischemic Patients: Advances in Diagnosis and Treatment

Ventricular arrhythmias (VAs) in non-ischemic cardiomyopathy (NICM) present significant clinical challenges due to their diverse etiologies and complex arrhythmogenic substrates, which differ from those in ischemic heart disease. Recent advancements in imaging, electrophysiological mapping, and ablative therapy have improved the management of these arrhythmias. This review examines the spectrum of NICM subtypes, discussing their pathophysiology, prevalence, genetic determinants, and associated arrhythmias. It also explores contemporary ablative techniques, including epicardial, bipolar, and irrigated approaches, as well as emerging modalities such as stereotactic body radiation therapy (SBRT). The role of novel technologies, including high-resolution mapping and artificial intelligence, is considered in refining diagnosis and treatment. This article provides a comprehensive overview of current management strategies and discusses future directions in the treatment of VAs in NICM patients.

Cardiac venous system mapping for ventricular arrhythmia localization

The coronary venous system offers a route for mapping and ablation of ventricular arrhythmias with suspected epicardial or intramural origins. Coronary venous mapping helps the operator to select the best ablation approach, decide when percutaneous epicardial access may be necessary and provides an opportunity for therapeutic interventions, including radiofrequency application inside the coronary veins or ethanol infusion. In this article we review the anatomy of the coronary venous system, the scenarios in which coronary venous mapping can be helpful and the technical aspects involved in coronary venous mapping.

Contemporary Trends in Pulsed Field Ablation for Cardiac Arrhythmias

Pulsed field ablation (PFA) is a catheter-based procedure that utilizes short high voltage and short-duration electrical field pulses to induce tissue injury. The last decade has yielded significant scientific progress and quickened interest in PFA as an energy modality leading to the emergence of the clinical use of PFA technologies for the treatment of atrial fibrillation. It is generally agreed that more research is needed to improve our biophysical understanding of PFA for clinical cardiac applications as well as its potential as a potential alternative energy source to thermal ablation modalities for the treatment of other arrhythmias. In this review, we discuss the available preclinical and clinical evidence for PFA for atrial fibrillation, developments for ventricular arrhythmia (VA) ablation, and future perspectives.

Intramural Ventricular Arrhythmias: How to Crack a Hard Nut

PURPOSE OF THE REVIEW

Successful catheter ablation of ventricular arrhythmias depends on identifying the critical tissues that sustain the arrhythmia. Increasingly, the intramural space is being recognized as an important source of idiopathic and reentrant ventricular arrhythmias, representing a common cause of ablation failure. A systematic approach to mapping and ablating these arrhythmias is key to optimize outcomes.

RECENT FINDINGS

Intramural ventricular arrhythmias are common in certain anatomical locations such as the left ventricular ostium or the interventricular septum. In these cases, mapping of the septal coronary veins provides an opportunity to explore the intramural compartment of the septum to perform activation mapping, entrainment and/or pace mapping. When an intramural arrhythmia is identified, ablation may require radiofrequency application from multiple sites, prolonged lesions, or special ablation techniques such as bipolar ablation or transvenous ethanol injection. Identification of intramural ventricular arrhythmias depends on comprehensive mapping that should include the coronary venous system, and ablation often requires advanced techniques. This paper provides a guide on when to suspect an intramural ventricular arrhythmia in the electrophysiology laboratory and how to approach mapping and ablation in these challenging cases.

Anatomical vs. electrophysiological approach for ablation of premature ventricular contractions originating from the left ventricular summit (ISESHIMA-SUMMIT Study)

AIMS

Catheter ablation (CA) of idiopathic ventricular arrhythmias (VAs) from the epicardial left ventricular summit is challenging. The endocardial approach targets two sites: the endocardial closest site (ECS) to the epicardial earliest activation site (epi-EAS) and the endocardial earliest activation site (endo-EAS). We aimed to differentiate between cases where CA at the ECS was effective and where CA at the endo-EAS yielded success.

METHODS AND RESULTS

Fifty-eight patients (47 men; age 60 ± 13 years) were analysed with VAs in which the EAS was observed in the coronary venous system (CVS). Overall, VAs were successfully eliminated in 42 (72%) patients: 8 in the CVS, 8 where the ECS matched with the endo-EAS, 11 at the ECS, and 15 at the endo-EAS. A successful ECS ablation was associated with a shorter epi-EAS-ECS distance (10.2 ± 4.7 vs. 18.8 ± 5.3 mm; P < 0.001) and shorter epi-EAS-left main coronary trunk (LMT) ostial distance (20.3 ± 7.6 vs. 30.3 ± 8.4 mm; P = 0.005), with optimal cut-off values of ≤12.6 and ≤24.0 mm, respectively. A successful endo-EAS ablation was associated with an earlier electrogram at the endo-EAS [23 (8, 36) vs. 15 (0, 19) ms preceding the QRS; P < 0.001] and shorter epi-EAS-endo-EAS interval [6 (1, 8) vs. 22 (12, 25) ms; P < 0.001], with optimal cut-off values of ≥18 and ≤9 ms, respectively.

CONCLUSION

Shorter anatomical distances between the epi-EAS and ECS, and between the epi-EAS and LMT ostium, predict a successful ECS ablation. The prematurity of the endo-EAS electrogram and a shorter interval between the epi-EAS and endo-EAS predicted a successful endo-EAS ablation.

Left Ventricular Summit Arrhythmias: State-of-the-Art Review of Anatomy, Mapping, and Ablation Strategies

The left ventricular summit (LVS) is the most common site of epicardial arrhythmias. Ablation of LVS arrhythmias continue to pose a challenge to the electrophysiologist because of its complex and intimate anatomical location. In this review, we undertake a detailed examination of the intricate anatomy of the LVS alongside a comprehensive synthesis of mapping and ablation strategies used to treat LVS arrhythmias.

Bipolar radiofrequency ablation of refractory ventricular arrhythmias: results from a multicentre network

AIMS

Advanced ablation strategies are needed to treat ventricular tachycardia (VT) and premature ventricular complexes (PVC) refractory to standard unipolar radiofrequency ablation (Uni-RFA). Bipolar radiofrequency catheter ablation (Bi-RFA) has emerged as a treatment option for refractory VT and PVC. Multicentre registry data on the use of Bi-RFA in the setting of refractory VT and PVC are lacking. The aim of this Bi-RFA registry is to determine its real-world safety, feasibility, and efficacy in patients with refractory VT/PVC.

METHODS AND RESULTS

Consecutive patients undergoing Bi-RFA at 16 European centres for recurring VT/PVC after at least one standard Uni-RFA were included. Second ablation catheter was used instead of a dispersive patch and was positioned at the opposite site of the ablation target. Between March 2021 and August 2024, 91 patients underwent 94 Bi-RFA procedures (74 males, age 62 ± 13, and prior Uni-RFA range 1-8). Indications were recurrence of PVC (n = 56), VT (n = 20), electrical storm (n = 13), or PVC-triggered ventricular fibrillation (n = 2). Procedural time was 160 ± 73 min, Bi-RFA time 426 ± 286 s, and mean Uni-RFA time 819 ± 697 s. Elimination of clinical VT/PVC was achieved in 67 (74%) patients and suppression of VT/PVC in a further 10 (11%) patients. In the remaining 14 patients (15%), no effect on VT/PVC was observed. Three major complications occurred: coronary artery occlusion, atrioventricular block, and arteriovenous fistula. Follow-up lasted 7 ± 8 months. Nineteen patients (61%) remained VT free. ≥80% PVC burden reduction was achieved in 45 (78%).

CONCLUSION

These real-world registry data indicate that Bi-RFA appears safe, is feasible, and is effective in the majority of patients with VT/PVC.