PO-04-073 ELECTRON MICROSCOPIC INSIGHTS FROM AN ACUTE PULSED FIELD MYOCARDIAL LESION

Pulsed field ablation (PFA) is a nonthermal ablative energy modality that increases membrane permeability by creating pores and causing chemical changes to the lipids proteins on cell membrane. However, little known about its effect membrane, organelle structure time course of lesion formation. To evaluate after PFA assess differences between 1- 4-hour PFA. Healthy swine underwent endocardial using an 11 Fr circular, multielectrode catheter (CellFX, Pulse Biosciences) in nanosecond pulsing mode. Pulses were delivered left ventricle under general anesthesia with fluoroscopic intracardiac echocardiography guidance. Two discrete lesions sampled 1 4 hours Transmission electron microscopy assessment was performed fixation paraformaldehyde glutaraldehyde. At 1-hour post-PFA, healthy myocytes normal sarcomeric structure, clear Z band, A band noted adjacent ablated (Figure). Mitochondria inside myocyte aligned parallel sarcomere filaments. Ablated other hand demonstrated disrupted structures randomly clustered misaligned. Cell membranes at border relatively preserved compared from within core lesion. PF noticeably more edematous areas coagulum could be seen capillaries. Alignment timepoint further disorganized. Fewer mitochondria per section observed scattered amongst damaged myocytes. There no sarcomeres anywhere hours. This study demonstrates significant rapid disappearance (∼ hour). The progressively deteriorate post ablation.