Power-Controlled, Irrigated Radio-Frequency Ablation of Gastric Tissue: A Biophysical Analysis of Lesion Formation

Figures

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  Fig. 1. Four repetitions of eight ablation settings. A Schematic showing grid location of ablation points on the stomach. B Gross image of the serosal surface following excision. C Gross image of the mucosal surface of the same section as B. The settings (i–viii) were as follows: (i) 65 °C at 0 mL min−1; (ii) 10 W at 5 mL min−1; (iii) 15 W at 5 mL min−1; (iv) 20 W at 5 mL min−1; (v) 30 W at 5 mL min−1; (vi) 10 W at 2 mL min−1; (vii) 15 W at 2 mL min−1; and (viii) 20 W at 2 mL min−1

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  Fig. 2. Box-and-whisker plots (median, first and third quartiles, range) of A impedance, B average catheter temperature, and C measured surface area for each setting investigated

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  Fig. 3. Measured lesion surface area and average catheter temperature during the ablation sequence for all visible, measured lesions. Lines shown are linear least squares regression fits to data points

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  Fig. 4. Tissue damage score (TDS) proportions for each setting for the muscularis and mucosa layers. TDS: (0) no damage, all healthy tissue present; (1) minimal damage, partial damage through layer; (2) moderate damage, damage present through entire thickness of layer; (3) excessive damage, damage entirely through layer and tissue has lost its structure; and (4) perforation, tissue layer no longer continuous. Since perforation did not occur, TDS was not assessed as level 4 for any ablation sequence

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  Fig. 5. Evaluation of tissue damage due to ablation using H&E stain for structural analysis. Panel I shows full-thickness tissue sections of ablated tissue. A 65 °C temperature-controlled; B 15 W at 5 mL min−1; C 20 W at 5 mL min−1, the border of the lesion is shown; and D 30 W at 5 mL min−1. Sections of tissue indicated by the green and red boxes in panel I are shown in panels II (muscularis) and III (mucosa) at higher magnification. Tissue destruction with swollen and elongated nuclei, edema, and extravasation are identifiers of tissue damage due to ablation. All (A–D) sections present muscularis damage, while (A,C) have no mucosal damage