Bipolar ablation of refractory atrial and ventricular arrhythmias: Importance of temperature values of intracardiac return electrodes

Abstract

Introduction: Bipolar radiofrequency catheter ablation (Bi-RFCA) emerged as an option for treatment of arrhythmias resistant to the conventional approach. Data on safety issues of Bi-RFCA, including temperature values of intracardiac return electrode (IRE) are lacking.

Objective: To determine the safety profile of Bi-RFCA regarding temperature measurements obtained from nonirrigated IRE of different sizes.

Methods: The study group consisted of consecutive patients after failed conventional RFCA who underwent Bi-RFCA.

Results: Out of 1510 RFCA performed in our center, 19 patients underwent Bi-RFCA due to refractory to previous RFCA ventricular arrhythmias (15 patients) or typical atrial flutter (four patients). Nonirrigated small (4 mm) and large (8 mm) tip catheters were used as IRE in 14 (including three cross-overs to 8 mm IRE) and five patients, respectively. A total number of 164 bipolar applications were performed (128 for 4 mm and 36 for 8 mm IRE). Maximal temperatures of 4 mm IRE were significantly higher than those of 8 mm IRE (63°C ± 16°C vs 43°C ± 4°C; P = .027). A significant rise of temperature and steam-pops, preventing further Bi-RFCA, occurred in seven patients treated with 4 mm IRE. Bi-RFCA using 4 mm IRE operated at significantly higher impedance values (211 ± 83 vs 143 ± 38; P = .04) and lower power values (mean 20 W ± 6 W vs 32 W ± 7 W, P = .0005; max 29 W ± 9 W vs 39 W ± 10 W, P = .027).

Conclusion: The use of 8 mm IRE for Bi-RFCA is associated with lower temperatures of the catheter used as ground and lower incidence of steam-pops which may suggest a better safety profile than 4 mm IRE. Determination of safety/efficacy balance requires further studies.

Keywords: atrial flutter; bipolar ablation; intracardiac return electrode; premature ventricular complexes; steam-pop; ventricular tachycardia.