Bipolar epi-endocardial radiofrequency ablation of ventricular tachycardia

Introduction

Deep intramural substrates may not be accessible using conventional unipolar ablation. Bipolar radiofrequency ablation(B-RFA)offers an alternative energy delivery method, that enables creation of deeper lesions and usually is delivered between 2 catheters positioned on the opposite sides of septum or inside great cardiac vein. We aimed to assess safety and efficacy of B-RFA when one of the catheters positioned in free epicardial space.Here, we present the largest patient cohort of patients underwent epi-endocardial B-RFA for ventricular tachycardia(VT).

Methods

All cases of epi-endocardial B-RFA performed from 2022till2025(n=9)were included. All procedures were performed under deep sedation. Epicardial access was obtained through a subxiphoid percutaneous approach. The return catheter was connected to the indifferent port of the primary generator via a dedicated Bipolar Ablation Adapter, replacing the conventional dispersive patch. B-RFA was performed in cases where the complete VT CL could not be recorded during high-density epicardial or endocardial mapping, with missing diastolic potentials on one side. Preprocedural imaging was performed in selected cases. All epicardial applications were delivered at sites >5mm from coronary arteries and without phrenic nerve capture.

Results

A total of 9 procedures in 7 patients were analyzed.All patients were men, with a median age of 65 years. Four had ischemic, two dilated, and one arrhythmogenic cardiomyopathy; four presented with VT storm. The median LVEF was 30%. All patients received beta-blocker therapy, and two (29%) were additionally treated with amiodarone. Four procedures(44%)were first-time, and 5 were repeat ablations following unsuccessful unipolar ablation. In all cases, endocardial access was achieved via a transseptal approach.The overall procedure duration was 186 minutes(IQR 177–205), with a fluoroscopy time of 19 minutes (IQR 14–22). Unipolar ablation was performed in eight of nine procedures at 40–50 W, with a total unipolar ablation time of 28 minutes(IQR 20.5–41.5) and 30 lesions(IQR 23–41). Bipolar ablation was performed at 20–30 W, with a total ablation time of 19 minutes (IQR 17–23), 18 lesions (IQR 14–22), baseline impedance of 150 Ω(IQR 130–170), impedance drop of 17 Ω(IQR 15–19), and intercatheter distance of 15 mm(IQR 13–18).

The bipolar ablation sites included the LV free wall in 8 cases, the RV free wall in 2 cases (in one case both). Steam pops occurred in 2 cases, both on the LV free wall, without subsequent pericardial effusion. No other complications were observed. During a median follow-up of seven months (IQR 5–14), two patients (after three procedures) experienced recurrence of sustained VT.

Conclusion

Endo-epicardial B-RFA is feasible, safe and effective approach in patients with structural heart disease and deep intramural scar and may be the treatment method of first choice. In most cases additional unipolar lesions were applied.