Intracardiac pulsed field ablation: Proof of feasibility in a chronic porcine model

Abstract

Background: Radiofrequency (RF) has become an accepted energy source for myocardial ablation but may result in discontinuous lesions and nontargeted tissue injury. We examined the feasibility and safety of lesion formation using high-amplitude, bipolar pulsed electric fields delivered from a multielectrode array catheter.

Objective: The purpose of this study was to compare duty-cycled radiofrequency ablation (RFA) to pulsed field ablation (PFA) in terms of acute electrical effects, 2-week lesion formation, and injury to nontargeted tissues.

Methods: Intracardiac ablations were performed in 6 pigs using a circular pulmonary vein ablation catheter. The energy source for ablation delivery was randomized to deliver either PFA or RFA to 3 atrial endocardial sites. Bipolar pace capture and electrogram amplitude measurements were recorded at each site. Histopathology and necropsies were performed after 2 weeks.

Results: The circular pulmonary vein ablation catheter was used to deliver pulsed electric fields to produce cardiac lesions without skeletal muscle stimulation. Evaluating all ablations in each site, electrogram amplitudes were reduced to <0.5 mV in 67.5% of PFA vs 27.0% of RFA deliveries (P <.001). Bipolar cardiac capture was lost after 100% vs 92.0% of PFA vs RFA (P = .005). At 2 weeks, PFA resulted in consistent transmural and homogeneous replacement fibrosis devoid of lingering myocyte "sequesters." RFA lesions showed a stronger inflammatory response extending to the epicardial fat, arterial injury, and thrombosis. Neither PFA nor RFA lesions showed endocardial thrombus.

Conclusion: Intracardiac PFA can be feasibly delivered from a circular catheter to create fibrotic lesions that have acute electrical effects, without injury to nontargeted tissue.

Keywords: Atrial fibrillation; Cardiac ablation; Irreversible electroporation; Pathology; Pulmonary vein isolation; Pulsed electric field; Radiofrequency; Transmurality.