Reduction in Pulmonary Vein Stenosis and Collateral Damage With Pulsed Field Ablation Compared With Radiofrequency Ablation in a Canine Model

Figures

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  Figure 1.. Rotational angiography was used for catheter positioning and serial computed tomography imaging for chronic pulmonary vein (PV) anatomical measurements. Distal (left) and proximal (right) ablations were performed for the pulsed field ablation (A) and irrigated radiofrequency catheters (B). Examples of 3-dimensional models (C) were based on serial contrast imaging at baseline and each chronic time point with identified ablation sites for PV cross-sectional area measurements. Red (irrigated radiofrequency [IRF]), blue (pulsed field ablation [PFA]), and beige (control) indicate randomized treatments of IRF or PFA to be received by the superior or inferior PVs in these baseline examples.

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  Figure 2.. Three-dimensional model of 2 treated left superior pulmonary veins over 5 time points through the 12-week study. The top branch in each row was treated with either irrigated radiofrequency (IRF; top row) or pulsed field ablation (PFA; bottom row), and the bottom branch in each row served as a control vessel. Vessel constriction over time was assessed based on measurements of the cross-sectional area at the treated section, compared with preablation measurements (first column). Measurements were made immediately after the bifurcation in vessels. Control and PFA-treated vessels showed no change in diameter or <10% decrease in diameter over the 12 wk survival.

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  Figure 3.. Three-dimensional model of 3 left superior pulmonary veins treated with irrigated radiofrequency (IRF; top row) or pulsed field ablation (PFA; bottom row) based on CT imaging. At 2 weeks, IRF delivery resulted in complete occlusion of the vessel (top right). PFA delivery had no significant reduction of pulmonary vein cross-sectional area in the same anatomic target. Fluoroscopy image (middle column) demonstrates positioning of the PFA or IRF catheter. Proximal and distal ablation measurements are shown for each vein (green).

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  Figure 4.. Pulmonary vein (PV) area and diameter changes for control vessels, irrigated radiofrequency (IRF)–treated PVs, and pulsed field ablation (PFA)–treated PVs followed from baseline to 12 weeks. Time point 0 represents baseline before the ablation in the summary graphs of distal (A) and proximal (B) PV ablation sites showing that IRF reached the most severe diameter reduction at the 4-week time point and recovered (distal) or maintained the reduction (proximal) for the remainder of the study. The same degree of reduction was not observed in the PVs treated using PFA. One subject was lost at the 8-week time point (*). The numbers of graded control or ablation site assessments of PV stenosis are shown in C for control, IRF-treated, and PFA-treated vessels at each study time point. Vessels meeting a 10%–70% diameter reduction (equal to 19%–91% area reduction) were counted among the total number of targets measured (far right). Decreased number of total targets at the 8-week time point is due to one deceased animal. PFA-treated targets never exceeded a 10% diameter reduction from baseline after the 2-week time point while IRF-treated targets experienced all stenosis levels, from >10% to…

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  Figure 5.. Necropsy findings, enhanced by TTC staining, of targeted pulmonary vein (PV) orifices (proximal) after pulsed field ablation (PFA; circled in black) or irrigated radiofrequency (IRF; circled in white) ablations 12 wk after treatment for 2 different subjects. In the image on the left, the subject’s inferior PVs were treated with PFA (white, circled) and superior PVs were treated with IRF (black, circled). In the image on the right, the subject’s inferior PVs were treated with IRF (black, circled) and superior PVs were treated with PFA (white, circled). Rulers are in cm and mm units.

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  Figure 6.. Fixed-tissue gross image panel with examples of cross sections through pulmonary lobes after irrigated radiofrequency (IRF) or pulsed field ablation (PFA) deliveries that were made distant (distal) to the venous orifices 12 wk earlier. Clear evidence of collateral damage (circled) was observed in the IRF treated lobe, but no evidence of damage was found after PFA. Asterisks are inserted in or near pulmonary vein targets. PV indicates pulmonary vein.

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  Figure 7.. Photomicrographs of distal pulmonary veins (an asterisk marks each lumen) that were ablated with irrigated radiofrequency (IRF) or with pulsed field ablation (PFA) to evaluate potential chronic (12-week old) collateral damage. IRF ablations caused widespread perivenous fibrosis (F) with loss (arrow heads) and distortion of bronchiolar cartilage (C), as well as mucus (M) accumulation and epithelial flattening in nearby airways. No evidence of increased fibrosis or airway changes were noted after PFA. Masson trichrome stains. A indicates artery.

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  Figure 8.. findings of the right and left vagus nerves (marked by dotted lines) after pulmonary vein ablations via irrigated radiofrequency (IRF; top row) or pulsed field ablation (PFA; bottom row) in the distal site of the ipsilateral pulmonary vein (arrow heads) 12 wk after treatment. Juxtaposed to the IRF ablation sites, focally extensive fibrosis on the esophagus (E) that also involved the main vagus nerve branch (arrows) was noted in IRF 7/8 treatments. Affected vagal nerves showed degeneration with severe endo- and perineural fibrosis on histology (Masson trichrome stains). No gross or histological lesions were detected after PFA treatments. Ao indicates aorta; LI, left inferior; and RI, right inferior.