Temperature-controlled bipolar radiofrequency ablation: An ex vivo study for optimizing efficacy and safety...

Clear indicators for efficacy and safety of bipolar radiofrequency catheter ablation (BRFA) remain undefined.

This study aimed to investigate predictive indicators of transmural lesion formation and steam pop in BRFA.

In an ex vivo model, BRFA was performed with either the QDOT Micro or ThermoCool SmartTouch SF as the active catheter and the DiamondTemp ablation (DTA) as the return catheter. Predictors of transmural lesion formation and steam pop occurrence were investigated.

A total of 391 BRFA applications were conducted under various catheter tip and tissue contact configurations with interelectrode distance of 6-27 mm. The ablation index (AI) adjusted for interelectrode distance was effective in predicting transmural lesion formation, with AI increasing linearly as interelectrode distance increased. Logistic regression revealed that the coefficient for AI was -0.040 (standard error, 0.0067; 95% confidence interval, -0.053 to -0.027; P < .0001); for interelectrode distance, it was 2.2 (standard error, 0.35; 95% confidence interval, 1.5-2.9; P < .0001). The AI required to achieve transmural lesion formation was calculated as AI = 54 × interelectrode distance - 260. Steam pops on the active side occurred only during power-controlled BRFA and were absent with a 45°C cutoff. On the return side, steam pops occurred above 55°C. Higher DTA temperatures resulted in deeper cracks.

An AI adjusted for interelectrode distance strongly predicted transmural lesion formation. Temperature-controlled BRFA with a 45°C cutoff for the active catheter and 55°C for the return catheter may prevent steam pops. Furthermore, steam pops induced by higher electrode temperatures may result in the formation of deeper cracks.