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A Novel Suction-assisted Probe For Epicardial Pulsed Field Ablation
M. Cassandra Witt, Matthew R. Schill, Mohamed A. Zayed, Ralph J. Damiano, Christian W. Zemlin.
Washington University, Saint Louis, MO, USA.
BACKGROUND: Achieving reliable epicardial transmural ablation on the beating heart remains a challenge in the minimally invasive surgical treatment of arrhythmias. Thermal energy sources are limited by heat exchange with intracavitary blood, which stabilizes the endocardial temperature and prevents transmural ablation. Pulsed field ablation (PFA), a nonthermal, electroporation-based technology, offers a potential solution. We developed a novel epicardial PFA device to achieve transmural epicardial ablation on the beating heart and evaluated its performance.
METHODS: A suction-assisted epicardial PFA probe was designed and 3D printed using thermoplastic polyurethane with two embedded parallel electrodes. Initial testing was performed in a potato model at a fixed voltage (550 V), pulse width (100 µs), and frequency (1 Hz), with varied pulse number (1 to 50). Lesion area, width, and depth were quantified using digital image analysis. The probe was subsequently tested in ex-vivo Langendorff-perfused beating canine hearts (n=2), using variable voltage (500-1100 V). Epicardial PFA was delivered to atrial and ventricular myocardium, followed by perfusion with triphenyl tetrazolium chloride (TTC) and gross sectioning to assess lesion depth and transmurality.
RESULTS: Suction provided stable probe-tissue adherence and consistent lesion formation. In the potato model, increasing pulse number produced progressively larger and deeper lesions. Mean lesion area increased from 10.5 ± 1.2 mm² at 1 pulse to 28.5 ± 1.2 mm² at 30 pulses (p < 0.01), while mean lesion width ranged from 4.7 ± 0.5 mm to 8.9 ± 1.1 mm (p < 0.01). Mean lesion depth increased from 2.7 ± 0.2 mm to 4.3 ± 0.3 mm with increasing pulse number (p < 0.01). In ex-vivo hearts, epicardial PFA was able to produce transmural lesions in atrial myocardium at the highest voltage attempted (1100V, 2/2 lesions were transmural), with a mean lesion depth of 1.3 ± 0.4 mm (Figure 1). Ventricular applications resulted in partial-thickness lesions. No surface charring or gross collateral tissue injury was observed.
CONCLUSIONS: We developed and tested a suction-assisted epicardial PFA probe designed to create transmural lesions. These results support the feasibility of epicardial PFA on a beating heart and provide a foundation for future in-vivo studies.
FIGURE 1: TTC-stained cross-sections of a left atrial lesion demonstrating transmural ablation.
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