Background: Bipolar radiofrequency ablation (B-RFA) has been reported as a bail-out treatment strategy for patients with therapy refractory ventricular arrhythmias (VA). Currently, existing solutions utilize two radiofrequency (RF) generators or custom-made solutions to enable B-RFA. However, the 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of VA cites custom-setting and the lack of monitoring of both catheter tip temperatures in commercially available devices as concern for B-RFA. In 2017 the first dedicated device received its CE mark (HAT500, Osypka AG, Rheinfelden, Germany).

Objective: This case series aimed to investigate if B-RFA using a novel dedicated RF generator (HAT500) is feasible to treat VA and to give preliminary in-hospital safety data.

Methods: Patients undergoing bipolar ablation for VA with a dedicated RF generator were included in this multicenter observational study. This device allows for simultaneous monitoring and use of two ablation catheters for B-RFA.

Results: A total of 26 procedures in 24 patients (57 ± 15 years; ♂ 75%) with 1.7 ± 1.3 previous ablations were studied. Idiopathic VA was the most common in (13/24), followed by dilated cardiomyopathy (6/24) and previous myocarditis (3/24). Two patients had ischemic cardiomyopathy.  Left ventricular ejection fraction was 48 % ± 15 (range: 23 – 74). The target sites were interventricular septum (8/26), outflow tract (11/26), aorto-mitral continuity (2/26), epi- and endocardial ablation in the left ventricle (3/26) and left ventricular summit (2/26). Maximal energy was 37.5 Watt (range: 24 – 50 Watt). The mean procedure time was 196.5 minutes ± 55.8 and the mean fluoroscopy time was 20.5 ± 10.8 minutes. 

Electroanatomic mapping (EAM) systems were used in every procedure, the majority with CARTO 3 (23/26) and the remaining cases with RHYTHMIA HDX. High density mapping was employed in 10 out of 26 procedures. Intracardiac echocardiography (ICE) was performed in 4 procedures.

Unipolar ablation in the same session was performed in 58% (15/26) and coronary angiography was carried out in 12 cases. Acute success with non-inducibility/abolition of all VA was achieved in 21/26 cases. In 3/26 cases adverse events were reported (2 uncomplicated vascular events, 1 atrioventricular block III° with pre-existing implantable cardioverter defibrillator).

Conclusion: Using a dedicated device for B-RFA seems feasible and appears to be safe. Larger prospective cohorts are needed to validate this novel method. Dedicated EAM Software or use of  ICE may further enhance procedural safety.

FIGURE 1: A: Schematic difference between custom-made solutions and an approach using a dedicated RF generator set-up for bipolar ablation B: Exemplary cable set-up with CARTO3 © (C) is shown. C: Graphic representation of target sites for bipolar ablation in this cohort (inset): Outflow tract morphologies (a), LV-summit (b), aorto-mitral continuity (c), endo- to epicardial (d), interventricular septum (e). B: Visualization via intracardiac echocardiography with catheters in high posterior septum and great cardiac vein D: Intracardiac echocardiography of catheters during energy application in pulmonary artery and great cardiac vein. A major limitation of mapping and ablation by using bipolar catheter ablation is the disappearance of one catheter in EAM during energy application.lar catheter ablation supporting the usefulness of intracardiac echocardiography (B).