Do different waveform configurations and irrigation rates affect temperature dynamics during pulsed field ablation in bovine myocardium?
Waveform optimization and active cooling during pulsed field ablation significantly mitigate thermal effects at the tissue interface in a preclinical model.
AIMS: Pulsed Field ablation (PFA) is a non-thermal ablation modality with functional myocardial sparing. Recent evidence suggests that clinically used PFA systems may produce non-negligible thermal effects, particularly at the tissue-catheter interface, potentially increasing the risk of thrombo-embolic complications. This study sought to characterize the temperature dynamics of two PFA pulse waveforms, delivered using a variable-loop circular catheter, under different irrigation conditions. METHODS AND RESULTS: In total, 132 ablations were performed on 31 bovine myocardial tissue specimens, using Sequence₁ and Sequence₂ at two different irrigation rates-4 and 30 mL/min. Maximum temperatures and their rise from baseline were measured at the tissue surface, and at 3 and 7 mm depths, across different ablation conditions. Sequence₁ at 4 mL/min produced the highest surface temperature (56. 4°C 54. 9-58. 4) and temperature rise (ΔT: 19. 4°C 17. 9-21. 4). Sequence₂ at 30 mL/min showed the most favourable thermal profile, with significantly lower surface temperatures (40. 8°C 37. 9-43. 0, ΔT: 3. 8°C 0. 9-6. 0, P < 0. 0001). At 3 mm depth, temperature increases were reduced for all settings, but remained highest with Sequence₁ at 4 mL/min (42. 5°C, ΔT: 5. 5°C). At 7 mm depth, temperatures remained close to baseline. Both waveform and irrigation optimization independently and synergistically reduced tissue heating, with the Sequence₂ at 30 mL/min achieving the lowest thermal load at all depths. CONCLUSION: This study confirms that PFA can induce relevant thermal effects, especially at the tissue interface. However, waveform optimization and active cooling significantly mitigate these effects. Such strategies to minimize thermal effects should be implemented in clinical practice to enhance procedural safety.
Zito et al. (Wed,) studied this question.