Electrode Contact Force‐Controlled Bipolar Radiofrequency Ablation: Different Effects on Lesion Size between Dual‐ and Single‐Bath Preparations

BACKGROUND: During bipolar (BIP) radiofrequency (RF) ablation using two catheters in humans, each catheter is placed in separate cardiac chambers or spaces. We developed a contact force-controlled experimental preparation, and compared measurements made with two catheters placed in a single bath (SB), versus each catheter placed in separate baths, in order to assess the preparation-dependent differences in the results of BIP-RF ablation. METHODS: In the SB experiments, a porcine heart was placed in the center of the bath, while in the dual-bath (DB) experiments, it was placed between two half baths communicating through windows. RESULTS: The initial impedance was greatest (110.5 ± 7.2 Ω) with the BIP-DB, followed by the BIP-SB (92.0 ± 5.6 Ω) and the unipolar (UNIP) DB (84.9 ± 4.7 Ω) configurations. During 50-W ablation for 60 seconds at a 20-g contact force, the root mean square voltage was 75.7 ± 2.5 V in the BIP-DB, 68.0 ± 2.1 V in the BIP-SB, and 66.8 ± 2.0 V in the UNIP-DB. The mean surface lesion diameters were similar among the three configurations. However, the endocardial lesion depth was 5.60 ± 0.56 mm with the BIP-DB, 4.71 ± 0.64 mm with the BIP-SB, and 4.24 ± 0.58 mm with the UNIP-DB configuration. On average, the endocardial lesions were significantly deeper than the epicardial ones. CONCLUSIONS: BIP ablation created much deeper lesions as compared to UNIP ablation. Lesion depth could be different depending on experimental preparation, and contact force-controlled DB preparation may be a much more appropriate model for studying the effects of BIP ablation.