Stent-based electrode for radiofrequency ablation in the rat esophagus: a preliminary study

Figures

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  Figure 1. Schematic illustration of the radiofrequency ablation using the stent-based electrode in the rat esophagus and representative TUNEL-stained images indicating the resulting therapeutic effects.

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  Figure 2. Radiofrequency (RF) ablation using a stent-based electrode in gastric cancer cells to verify apoptotic effects. (a) Reduction in the viable cell number was determined using an annexin V assay. (b) Graph showing the total quantity of apoptotic cancer cells (early + late apoptotic cells). (c) Maximum temperature in accordance with the power setting used for the RF ablation.

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  Figure 3. Temperature changes during radiofrequency (RF) ablation via the stent-based monopolar RF electrode (SE) in the rat esophagus. (a) Representative photographs and thermal images obtained during RF ablation of the rat esophagus through the SE at a 40 W power setting for 60 s. (b) Graph showing the recorded temperature changes during RF ablation at 30, 40 and 50 W. All RF energies were applied starting at the same time point (arrowhead) until the temperature reached 70 ℃ (arrow). (c) Initial heating temperature (red line). (d) Cooling temperature changes after the cessation of RF energy transfer (blue line). (e) Impedance profile changes during RF ablation in the exposed rat esophagus in accordance with different power settings at 30, 40, and 50 W. (f) Gross finding by various RF parameter in the extracted rat esophagus.

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  Figure 4. In-vivo experimental design, impedance, and weight changes. (a) Flow diagram of the in-vivo study design and follow-up. (b) Radiographic images showing the technical steps for the radiofrequency (RF) ablation using a stent-based monopolar RF electrode (SE) in the rat esophagus. Step 1, a micro guidewire was inserted through the esophagus into the stomach; step 2, a SE loaded delivery system (arrowheads) was advanced over the guidewire; step 3, the olive tip of the SE (arrowheads) was placed at the margin of the diaphragm under fluoroscopic guidance; step 4, the adjustable SE (arrowheads) was deployed with a diameter of 4 mm and a length of 3 mm to fully attach the electrode to the entire inner wall of the rat esophagus. (c) Impedance changes during RF ablation at 40 W for 60 s in the rat esophagus. (d) The body weight changes after RF ablation. *p < 0.05, **p < 0.01, ***p < 0.001.

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  Figure 5. Representative microscopic images and serial histological findings at the indicated time points after radiofrequency (RF) ablation via the stent-based monopolar RF electrode (SE). (a)Representative microscopic images of hematoxylin & eosin-, Masson’s trichrome-, heat shock protein 70 (HSP70)-, and terminal deoxynucleotidyl transferase mediated dUTP nick and labeling (TUNEL)-stained tissue slides. (b) Graphs of the histologic findings indicating serial changes to the thicknesses of the submucosal fibrosis and epithelial layers, the degrees of inflammatory cell infiltration, collagen deposition levels, and TUNEL and HSP 70 positivity. *p < 0.05, **p < 0.001.