PO-01-004 DEVELOPMENT OF A THERMOCHROMIC BENCHTOP MODEL FOR A RAPID, EFFICIENT, AND COST-EFFECTIVE OPTIMIZATION OF PULSED FIELD ABLATION THERAPIES

Abstract

Pulsed Field Ablation (PFA) is a non-thermal alternative to RF providing a tissue preferential therapy with no thermal necrosis. PFA applies high voltage, short electrical pulses to create irreversible cell membrane pores causing cell death. Since energy application intrinsically leads to Joule heating, parameters optimization is vital to obtain a therapy that limits temperature below 50°C, the cardiac thermal damage threshold. This constraint creates a complex multi-variable problem, requiring multiple in vivo studies to mitigate the likelihood of thermal damage, which can be inefficient and costly. Bench methods using ex vivo tissue or gels with thermal probes are inadequate as they rely on orientation and proximity to hotspots. The aim of this research was to develop a thermochromic phantom gel model that changes color when temperature exceeds the critical thermal damage threshold, enabling better visualization of thermal profile for PFA systems. The development of this gel model included a combination of saline with polyacrylic acid and a reversible thermochromic pigment that changes color ≥45°C. The gel allows any catheter to be coated. The coated Abbott VoltTM PFA catheter was placed in a 32°C heated saline bath (to obtain ΔT of 13°C, analogous to that observed between 37°C and 50°C) and PFA was applied using VoltTM PFA Generator. During ablation, real-time gel color change is noted (Purple<Threshold≤Light blue). Using this model, we compared an optimized PFA waveform to a Positive Control waveform known to cause thermal damage in vivo (N=1 section from 1 animal). Three gel batches were used to understand batch variability (N=15 at each batch). The positive control showed color change in 84% of trials. During ablation, light blue spots appeared on electrodes that enlarged with continued ablation, highlighting heat stacking for the Positive Control waveform. No color change was observed for the optimized waveform (N=45). The non-thermal nature of the lesion created by the optimized VoltTM PFA waveform was also confirmed in in vivo studies via histopathology (N=6 sections from 2 animals). This study demonstrated that the gel model can capture thermal damage risk with a Positive Control (84%). The optimized VoltTM PFA system waveform via the gel model is thermally safe, as confirmed via histopathology. This bench model offers an efficient and cost-effective method for optimizing PFA waveforms.