https://doi.org/10.1007/s00392-025-02625-4
1Universitätsklinikum Tübingen Innere Medizin III, Kardiologie und Kreislauferkrankungen Tübingen, Deutschland; 2Institute of High Magnetic Fields Vilnius, Litauen; 3University Hospital Tübingen Department of Urology Tübingen, Deutschland
Background: Nanosecond pulsed electric fields (nsPEF) are a promising method for cardiac Pulsed Field Ablation, currently in early clinical trials. Effective ablation often requires high voltages, more pulses, and higher frequencies, which can raise tissue temperatures due to Joule heating. Fractionated pulse delivery can help mitigate thermal effects and potentially enhance electrosensitization, increasing cell damage.
Objective: This study evaluates the effects of fractionated nsPEF on treatment efficacy and its selectivity against cardiomyocytes, aiming to determine if fractionation improves ablation outcomes.
Methods: We used monolayers of HL-1 murine cardiomyocytes, MHEC 5-T murine endothelial cells, AC16 human cardiomyocytes, and HUVEC human endothelial cells. A robotic system positioned electrodes orthogonally to the substrate. Cell viability and permeability were measured using wide-field fluorescence microscopy, with stained areas matched to simulated electric fields for dose-response curves. Fractionation effects were also validated in an ex vivo murine model.
Results: Fractionated nsPEF increased plasma membrane permeability for YO-PRO-1 dye in cardiomyocytes. The ED50 (electric field affecting 50% of cells) for fractionated nsPEF (four trains of 50 pulses at 10 Hz, 300-ns duration, 50-second intervals) was lower than for a single train of 200 pulses (p<0,0001). This corresponded with enhanced cell-killing efficiency, with similar effects in endothelial cells. Ex vivo results showed a larger ablation area with fractionated nsPEF (p<0,0001).
Conclusion: Fractionated nsPEF improves cardiac ablation efficiency by enhancing membrane permeability and cell-killing while maintaining selectivity. These findings suggest that fractionated delivery could optimize nsPEF therapies, offering a more effective approach for cardiac ablation.
Keywords: Nanosecond Pulsed Field Ablation, Electrosensitization, Fractionated nsPEF, cardiomyocytes, electroporation