MP-453088-3 PULSED FIELD ABLATION USING A NOVEL INSULATED ELECTRODE DESIGN REDUCES MICROBUBBLE FORMATION WHILE CREATING LARGE AND HOMOGENEOUS LESIONS IN VITRO

Abstract

Pulsed Field ablation (PFA) is a promising strategy for treatment of cardiac arrhythmias. But there are unresolved issues pertaining to its safety and efficacy, specifically microbubbles and lesion homogeneity. Conventional electrode designs result in the ablation electrode surface to be largely in contact with blood, leading to electrolysis and microbubbles during PFA. Additionally, the blood in contact with the electrodes provides a conductive path for the energy, directing it away from the targeted tissue. This in turn can result in non-homogeneous application of energy, thereby, impacting lesion size and durability. We hypothesized that PFA using a novel ablation catheter with an insulated electrode design (Sirona Medical Technologies, SMT) (Figure), in vitro could achieve large, homogeneous lesions while minimizing microbubbles by reducing exposure to the blood path. In total, 18 single-shot, bipolar (2.2 kV) pulsed field applications were delivered using the SMT PFA catheter for 3, 6, and 10 bursts in a potato model. The potato model is considered a relevant and well-accepted model for in vitro study of irreversible electroporation (IRE) due to its similar response to IRE as mammalian cells. Applications were closely observed for presence of microbubbles. Lesion were assessed for thermal injury and the dimensions were analyzed and reported (diameter x depth) 24 h post-ablation. There was no discernible microbubbling observed during PFA at 20 pulses/burst, and only minor microbubbling was encountered at 40 and 60 pulses/bursts. All the lesions were large and homogeneous. With 3 bursts of PFA, lesions measured 7 mm x 3 mm (20 pulses/burst), 10 mm x 4 mm (40 pulses/burst), and 12 mm x 4 mm (60 pulses/burst), respectively. With 6 bursts of PFA, lesions measured 14 mm x 5 mm (20 pulses/burst), 15 mm x 6 mm (40 pulses/burst), and 17 mm x 6 mm (60 pulses/burst), respectively. Lastly, with 10 bursts of PFA, lesions measured 18 mm x 8 mm (20 pulses/burst), 19 mm x 9 mm (40 pulses/burst), and 21 mm x 10 mm (10 pulses/burst), respectively. As such, there was a direct dose response as a function of the number of pulses/burst and the duration of applications. Furthermore, there was no evidence of thermal injury. PFA with the SMT catheter utilizing a novel, insulated electrode design in vitro can create large, homogenous lesions with no discernible/minimal microbubbles. These findings have significant safety and efficacy implications.