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 5 .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.

Feasibility, safety, and durability of porcine atrial ablation using a lattice‐tip temperature‐controlled radiofrequency ablation catheter

“…The histological evaluation revealed lesions to be transmural with necrosis, inflammation, and fibrotic areas. The areas of mild focal hemorrhage, giant cells, and mineralization that were seen are all consistent with the healing phase of RF lesions, as was the extension of inflammation into the epicardial tissue 13 . The 100% transmurality rate seen with the lattice‐tip catheter is in line with the durable vein isolation observed in this study and supports improved ablation efficiency with this catheter.…”

Novel and Emerging Tools and Technologies in Cardiac Electrophysiology: What’s on the Horizon in 2020?

“…Aside from an ultra-rapid mode of ablation, electroporation can also be tailored based upon tissue specificity to preserve sensitive structures in the path of ablation energy (eg, vessels, nerves). [28][29][30] Furthermore, IRE is unaffected by the "heatsink" effect that can sometimes impede conventional forms of thermal ablation. Recently, the term "pulsed field ablation" has been used to describe nonthermal monophasic-or biphasic-waveform, field-based cardiac arrhythmia ablation.…”

“…Recently, the term "pulsed field ablation" has been used to describe nonthermal monophasic-or biphasic-waveform, field-based cardiac arrhythmia ablation. 27,[29][30][31] Each therapeutic application consists of a series of electric pulses delivered as a pulse train. For bipolar systems, during each pulse, current flows in a bipolar manner between individual electrodes on the multielectrode catheter, which radiates an electric field that surrounds the catheter.…”

“…After exposure to a series of pulse trains, the hyperpermeabilization of the cell membrane becomes permanent, which leads to cardiomyocyte death followed by lesion formation through replacement fibrosis. 30 During each pulse, current flows in a bipolar manner between individual electrodes typically on a multielectrode catheter that radiates an electric field to surround the catheter. After exposure to a series of pulse trains, the hyperpermeabilization of the cell membrane becomes permanent, which leads to cell death.…”

“…Preliminary data suggest that ablation lesions created in the targeted myocardium using this approach are durable, ensuring preserved integrity and function of collateral structures such as the esophagus, lungs, pulmonary veins, coronary arteries, and the vagus and phrenic nerves. [29][30][31] The focus of development of this new technology has been to optimize pulse parameters to reduce complications, including char formation and thermally mediated embolic events. While not observed to date, high-voltage applications driving high-level current still have the potential to create heat in the immediate vicinity of the electrode, thereby increasing the probability of char formation and thermally mediated embolic events.…”