Lesion Formation in Cardiac Pulsed‐Field Ablation: Acute to Chronic Cellular Level Changes

Figures

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  FIGURE 1. Representation of cardiac myocardium before and after PFA. (A) Pre‐ablation depiction of the myocardial tissue structure, from endocardium to epicardium. (B) Representative PFA ablation, showing the e‐field with higher field density closest to the ablation catheter. (C) Post‐ablation depiction. Note the replacement of cardiomyocytes with uniform fibrosis, preserved nerves and vessels, neoendocardium formation and neovascularization, and intact ECM. [Colour figure can be viewed at wileyonlinelibrary.com]

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  FIGURE 2. Progression of PFA lesion time course with TTC and Masson's Trichrome staining. (A) Acute lesion: TTC‐stained tissue allows the lesion to appear distinct from the surrounding myocardium but is not fully mature. Some endocardial hemorrhage was observed. Trichrome staining reveals distinct borders [23]. (B) Subacute lesion: very clear and defined lesion borders both with TTC and Trichrome staining; gross lesion appears whiter with more calcification than later timepoints [17]. (C) 7‐day lesion: clear borders with TTC staining; gross lesion appears whiter with less calcification [21]. (D) Chronic lesion: lesion with TTC staining whiter and slightly more transparent in appearance. Lesion appears mature with trichrome staining; tissue thinning in the lesion zone was observed [24]. All images were reprinted with permission from cited sources. [Colour figure can be viewed at wileyonlinelibrary.com]

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  FIGURE 3. Comparison of histology between ablation modalities. (A) Representative histology of RF lesion in ventricular tissue, demonstrating the transition from coagulation necrosis at the core of the lesion, contraction band necrosis at the periphery, and viable myocytes [11]. (B) Representative cryo lesion in ventricular tissue, demonstrating the transition between coagulation necrosis in the lesion zone and viable myocytes [45]. (C) Example demonstrating healthy tissue, RF scar, and PF scar in the same ventricular lesion zone. (D) Atrial tissue demonstrating PFA encompassing previous RF scar, demonstrating distinct histological differences [17]. All images were reprinted with permission from cited sources. [Colour figure can be viewed at wileyonlinelibrary.com]

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  FIGURE 4. Histology to assess collateral injury with PFA. (A) Representative sample of esophageal tissue following ablation in close proximity to the PFA catheter. Reproduced with permission from Koruth et al. No damage was observed. (B) Gross imaging and representative histology from the right phrenic nerve following PFA in close proximity, with no damage observed. (C) Representative views of the coronary artery following epicardial PFA in close proximity. Neointimal hyperplasic and tunica media fibrosis were noted at the 4‐ and 8‐week timepoints [44]. All images were reprinted with permission from cited sources. [Colour figure can be viewed at wileyonlinelibrary.com]