AB-452672-3 PRE-CLINICAL PULSED-FIELD ABLATION (PFA) USING A SINGLE-SHOT CIRCULAR LINEAR ABLATION CATHETER FOR PV ISOLATION

Abstract

Pulsed field ablation (PFA) is becoming the preferred energy treatment for pulmonary vein (PV) isolation. PFA application appears safe and effective and shortens procedure time. A circular linear ablation catheter may have advantages for single-shot delivery of PFA for PV isolation. To evaluate the feasibility of pusled field ablation for PV isolation with a circular linear ablation catheter. The Fiore™ catheter (EP Frontiers S.p.A., Italy; Figure) has two unique features: (1) an over the wire anchor and (2) an ablation element with linear electrodes. The anchor is positioned in the PV and guides the Circular Linear Ablation (CLA). The CLA can deliver PFA from a customized generator. Optimization of PFA parameters was conducted with a potato model in a saline bath by testing various energy pulses with bipolar and biphasic energy (500-1000 volts, pulse duration of 10-100 μs, interpulse pause of 10-400 μs, with a changing number of repetitions). The goal was to create circular ablations with a minimal depth of 3-4 mm. Following energy application images were acquired acutely and 18-24 hours after. Porcine in vivo testing (n=5 swine under general anaesthesia) with a deflectable sheath, evaluated PFA application at the left and right superior pulmonary vein, superior vena cava, and lateral wall of the right atrium with histopathology. In vitro ablations with three separate pulse trains demonstrated circular lesions with a diameter of up to 40 mm that were visible hours after the energy delivery. Average cross section of the circular lesions revealed an average depth of 3.2 mm with a surface width of 36 mm (Figure). Four applications (vs eight), from linear electrodes resulted in the most optimal and controlled circular lesions with central sparing and no off-target tissue destruction. Under fluoroscopic guidance, all positions in left and right atria, were easily accessed in all 5 animals (Figure). During PFA delivery, minimal skeletal muscle contraction was observed, without thermal ablation effect. Histopathology examination revealed acute changes in the atrial muscle structure. Chronic animal testing is ongoing to provide optimization of pulse trains and electrode to electrode sequencing to allow precise measurements of the PFA lesions depth. Following lesion optimization in an in vitro model, we demonstrate feasibility of delivering reproducible single-shot circumferential PFA lesions using a unique designed circular linear ablation catheter.