Safety and chronic lesion characterization of pulsed field ablation in a Porcine model

Figures

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  Figure 1. Porcine model summary. In six pigs, a low (±700 V) dose of pulsed field ablation (PFA) was delivered to the superior vena cava (SVC) (muscle sleeve portion), and a high (±1500 V) dose of PFA was delivered to the right atrial appendage (RAA), and right superior pulmonary vein (RSPV). The common inferior pulmonary vein (CIPV) was not ablated

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  Figure 2. Acute Isolation of the SVC, RAA, and RSPV. Immediately after the first pulse train delivery, electrograms for each of the targeted sites were reduced and after all four pulse trains were delivered, only far‐field signals remained. Complete electrical isolation of all structures was confirmed by entrance block. Entrance and exit block were confirmed for the SVC. RAA, right atrial appendage; RSPV, right superior pulmonary vein; SVC, superior vena cava

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  Figure 3. Ablation of the SVC. In‐situ necropsy finding, enhanced by triphenyl tetrazolium chloride (TTC) staining, 4 weeks after low‐dose PFA treatment of the SVC before (A) and after (B) opening the lumen. A continuous ablation line (dotted line) is readily visible under backlight illumination of the same specimen after formalin fixation (C). Histology confirms transmural replacement fibrosis and shows abrupt transition to normal, nontreated muscle via Masson's trichrome staining. White bar in (C) indicates slide origin for (D). C, collagenous portion of the SVC; E, endothelial side; F, fibrosis after ablation; M, muscle (untreated); PFA, pulsed field ablation; SVC, superior vena cava

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  Figure 4. Ablation of the RAA. In‐situ necropsy finding, enhanced by TTC staining, 4 weeks after high‐dose PFA treatment of the RAA when looking into the appendage (A) and after eversion of the appendage to display the endocardium (B). Widespread atrial replacement fibrosis is readily visible under backlight illumination of the same specimen after formalin fixation (C). Histology via Masson's trichrome staining confirms transmural replacement fibrosis in atrial wall segments that were originally made of irregular trabeculation/pectination. White bar in (C) indicates slide origin for (D). E, endothelial side; F, fibrosis after ablation; FT, fat tissue on epicardium (normal); M, muscle (untreated); PFA, pulsed field ablation; RAA, right atrial appendage; TTC, triphenyl tetrazolium chloride

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  Figure 5. Ablation of the RSPV. In‐situ necropsy finding, enhanced by TTC staining, 4 weeks after high‐dose PFA treatment of the RSPV when looking into its orifice (A) and after longitudinal opening towards the lung (B). There is good evidence of circumferential replacement fibrosis when the same formalin‐fixed specimen is examined under backlight illumination (C). Histology via Masson's trichrome staining confirms transmural replacement fibrosis that is covered by neointima and has normal adjacent myocardium (D). White bar in (C) indicates slide origin for (D). E, endothelial side; F, fibrosis after ablation; FT, fat tissue at cardiac base (normal); L, lung; M, muscle (untreated); N, neointima; PFA, pulsed field ablation; RSPV, right superior pulmonary vein; TTC, triphenyl tetrazolium chloride; U, untreated pulmonary vein orifice

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  Figure 6. (A) Collateral damage profile. Photomicrograph of the right phrenic nerve that illustrates no pathological changes 4 weeks after PFA treatment when low‐dose PFA was delivered in the SVC. (B) Histology of a pulmonary artery branch previously juxtaposed to a RSPV ablation and now showing arterial wall remodeling that consisted of mild fibrosis and loss of media myocytes. Photomicrograph from a right atrial appendage with perineural fibrosis and normal appearing artery (C). A, artery; L, lumen; N, nerve; PFA, pulsed field ablation; RSPV, right superior pulmonary vein; SVC, superior vena cava. *Fibrosis and myocyte loss

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  Figure 7. Three‐dimensional rendering of the RSPV constructed using contrast enhanced CT images from a single pig. 4 placements of the circular electrode array were positioned at the ostium of the RSPV with the shape of the catheter conforming to the inner surface of the ostium (A and B). Using a conservative field threshold of 550 V/cm and uniform 3 mm tissue thickness, the field isosurfaces predict a contiguous and transmural lesion volume (green) with lesion widths ranging 3–12 mm on the outer surface of the ostium and 6.5–15 mm on the inner surface (C and D). CT, computed tomography; RSPV, right superior pulmonary vein