Safety and Chronic Atrial Lesion Formation With a Large-Tip, Contact-Force-Sensing Multipolar Pulsed Field Ablation Catheter: Effect of Application Number in a Porcine Beating Heart Model

Figures

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  Figure 1.. Postprocedure and 30-day evaluation of pulsed field lesion delivered to pulmonary veins. A and C, Acute and (B and D) chronic isolation of right pulmonary veins obtained with both low-dose (A and B) and high-dose (C and D) pulsed field ablation (PFA), as observed on bipolar voltage maps on the CARTO system. PFA indicates pulsed field ablation.

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  Figure 2.. Postprocedure and 30-day voltage maps and corresponding gross necroscopic evaluation of pulsed field lesions in the right atrial posterior wall (RAPW). A and D, Postprocedure and (B and E) 30-day voltage maps, with corresponding gross necroscopic evaluation (C and F), of pulsed field lesions in the right atrial posterior wall for the investigated dosing regimens. Acute and chronic assessments of lesion contiguity are shown for both low-dose (A–C) and high-dose (D–F) pulsed field ablation (PFA), as observed on bipolar voltage maps acquired with the CARTO system. Corresponding chronic scar formation is demonstrated on gross necropsy and highlighted by dashed white lines (C and F). In A and D, solid purple circles represent ablation tags, while yellow tags indicate the course of the right phrenic nerve. Per study design, the ablation line connecting the superior vena cava (SVC) to the inferior vena cava (IVC) was intentionally incomplete (ie, lesions delivered to the inferior portion of the SVC–IVC line) to prevent sinus node injury.

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  Figure 3.. Histological evaluation of lesion transmurality extent at targeted sites. A, Schematic illustrating how transmurality extent was quantified as the percentage of lesion span within a single histological section demonstrating full-thickness (endo-epicardial) fibrosis. B, Representative longitudinal (radial) histological section through the right inferior pulmonary vein (RIPV), where blue staining indicates fibrotic tissue and red staining indicates viable myocardium; the yellow double arrow denotes lesion length and white arrows indicate myocardial wall thickness. This section demonstrates full transmurality (100%). C, Representative histological section from the left atrial (LA) roof treatment site (outlined in black), where only a limited segment (red bracket) demonstrates full-thickness fibrosis, corresponding to an estimated transmurality extent of ≈10%.

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  Figure 4.. Pulsed field ablation (PFA)–related minor histological effects on adjacent anatomic structures. A, Pulmonary artery (PA), (B and D) vessels, and (C) nerves adjacent to atrial myocardium. A, Right superior pulmonary vein (RSPV) ablation site (low-dose PFA) demonstrating mild mineralization (black outline) in the outer PA layer without significant intimal changes. B, Cavotricuspid isthmus (CTI) ablation site (low-dose PFA) showing minimal arterial wall thickening with limited intimal hyperplasia (black outline). C, Right inferior pulmonary vein (RIPV) region (high-dose PFA) demonstrating fibrous myocardial replacement with mild perineural fibrosis (black outlines) and small arteriole fibrosis (boxed). D, Higher magnification of the boxed region in C showing arteriolar fibrosis (arrow), consistent with localized microvascular injury without associated ischemic injury or clinical sequelae.

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  Figure 5.. Analysis of maximum transmurality extent on 30-day histology and the average catheter-tissue contact during ablation. A, Analysis of maximum transmurality extent on 30-day histology and (B) the average catheter–tissue contact (CF) during ablation for each anatomic target per randomized pulsed field ablation dosing regimen. CTI indicates cavotricuspid isthmus; LA, left atrium; RAPW, right atrial posterior wall; and RPV, right pulmonary veins.

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  Figure 6.. Histological sections at selected anatomic targets 30 days after pulsed field ablation (PFA). A and B, Right superior pulmonary vein (RSPV), (C and D) cavotricuspid isthmus (CTI), and (E and F) mitral annulus (MA) obtained 30 days after low- and high-dose PFA. Across both dosing groups, pulmonary vein targets (A and B) and right atrial sites including the CTI (C and D) frequently exhibited near-complete maximum transmurality extent (>80%). In contrast, lower transmurality extent was generally observed at the mitral annulus and left atrial roof. Representative sections from the higher-dose group (F) demonstrated greater transmurality compared with low-dose PFA (E), potentially reflecting increased application overlap.