Electrode Thermal Profile During Ventricular RF Ablation: A Novel Indication of Electrode Tissue Interface to Inform...

Electrode-tissue contact and orientation influence radiofrequency (RF) ablation heating, lesion size, and steam pops, and is not easily assessed. A catheter with 6 distal electrode temperature sensors provides thermal profiles that may help clarify electrode-tissue interactions.

The aim of this study was to evaluate the relationships between thermal profiles, catheter orientation, impedance fall, steam pops, and discordant temperature-impedance changes during ventricular RF ablation.

We analyzed 2,085 RF applications in 100 patients, titrating power to a maximum temperature <50 °C and impedance fall >10 Ω. Stable thermal profiles were classified as embedded, central, or peripheral. Catheter orientation from the force vector was classified as perpendicular, oblique, or parallel.

The thermal profile aligned with the force vector at 60.9% of stable sites, with 72.1% of peripheral profiles being oblique/parallel and 80.4% of central profiles being perpendicular. Impedance fall was discordant with temperature at 890 (42.7%) sites. Catheter orientation and thermal profiles differed for low temperature-high impedance fall, compared with high temperature-low impedance fall discordant sites (P < 0.001). An embedded thermal profile (all sensors ≥45 °C) most often occurred with perpendicular or oblique orientations, had the greatest impedance falls, and had the highest incidence of steam pops (8.6% vs 1.3%; P < 0.001). No steam pops occurred with impedance falls <14 Ω or maximum temperature <45.8 °C, or when impedance fall and temperature were discordant.

Electrode thermal profiles provide information complementary to force vector and impedance, reflecting electrode-tissue interactions that are also related to discrepancies in impedance fall and temperature during RF ablation. They can potentially help optimize RF ablation lesion size while avoiding steam pops.