Bipolar ablation of therapy-refractory ventricular arrhythmias: application of a dedicated approach

Abstract

Aims: Bipolar radiofrequency ablation (B-RFA) has been reported as a bail-out strategy for the treatment of therapy refractory ventricular arrhythmias (VA). Currently, existing setups have not been standardized for B-RFA, while the impact of conventional B-RFA approaches on lesion formation remains unclear.

Methods and results: (i) In a multicentre observational study, patients undergoing B-RFA for previously therapy-refractory VA using a dedicated B-RFA setup were retrospectively analysed. (ii) Additionally, in an ex vivo model lesion formation during B-RFA was evaluated using porcine hearts. In a total of 26 procedures (24 patients), acute success was achieved in all 14 ventricular tachycardia (VT) procedures and 7/12 procedures with premature ventricular contractions (PVC), with major complications occurring in 1 procedure (atrioventricular block). During a median follow-up of 211 days in 21 patients, 6/11 patients (VT) and 5/10 patients (PVC) remained arrhythmia-free. Lesion formation in the ex vivo model during energy titration from 30 to 50 W led to similar lesion volumes compared with initial high-power 50 W B-RFA. Lesion size significantly increased when combining sequential unipolar and B-RFA (1429 mm3 vs. titration 501 mm3 vs. B-RFA 50 W 423 mm3, P < 0.001), an approach used in overall 58% of procedures and more frequently applied in procedures without VA recurrence (92% vs. 36%, P = 0.009). Adipose tissue severely limited lesion formation during B-RFA.

Conclusion: Using a dedicated device for B-RFA for therapy-refractory VA appears feasible and safe. While some patients need repeat ablation, success rates were encouraging. Sequential unipolar and B-RFA may be favourable for lesion formation.

Keywords: Bipolar ablation; Premature ventricular contractions; Radiofrequency generator; Ventricular arrhythmias; Ventricular tachycardia.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.

Figures

Graphical Abstract

Figure 1

Clinical and ex vivo bipolar ablation setup. (A) Schematic overview on custom-made solutions and presented approach using a dedicated radiofrequency (RF) generator setup for bipolar ablation. (B) Experimental setup of custom catheter guiding blocks in a temperature-controlled saline bath with two irrigated 3.5 mm ablation catheters on either side. (C) Catheters are connected to a single ablation generator with two separate irrigation pumps.

Figure 2

Mid-term follow-up after bipolar ablation. (A) Freedom of ventricular arrhythmia (VA) was observed in 59% of patients within 12 months after initial B-RFA. (B) Lower VA recurrence rates were observed in patients with unipolar ablation followed by bipolar ablation (UA+B-RFA) compared with B-RFA alone. B-RFA, bipolar radiofrequency ablation; UA, unipolar ablation; VA, ventricular arrhythmia.

Figure 3

Lesion formation during common clinical bipolar ablation approaches. (A) Lesion volume and depth significantly increased after combination of sequential unipolar (SUA) and bipolar ablation (B-RFA), whereas energy titration did not significantly alter macroscopic lesion characteristics. (B) B-RFA with 50 W in regions of significant epicardial adipose tissue (EA) close to the coronary sinus (CS) significantly reduced lesion volume and depth compared with B-RFA at regions without EA. Commonly, no lesion was visible at the epicardial site (upper right image). B-RFA, bipolar radiofrequency ablation; EA, epicardial adipose tissue; SUA, sequential unipolar ablation.