Purpose: Animal studies of endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) of the liver have rarely been reported. We assessed the effectiveness and safety of EUS-RFA in pigs.
Methods: We conducted four experiments using newly designed RFA electrodes. In the first experiment, we ablated excised liver using 19 G electrodes with active electrode tips with lengths of 1, 1.5, and 2 cm. The second experiment was performed with the same electrodes as those used in the first experiment, but with the electrodes inserted into the livers of live pigs under EUS. In the third experiment, we tested the electrodes for water permeability. In the fourth experiment, we performed EUS-RFA on live pigs, using 19 G electrodes in 7/12 pigs and 18 G electrodes in 5/12 pigs. Complications were evaluated after 7 days of survival.
Results: The newly designed RFA electrodes achieved ablation of the liver. In the first experiment, the maximal sizes of the ablation areas were 27, 26, 24, and 25 mm at 10, 20, 30, and 40 W, respectively, with the 2-cm electrode. In the second experiment, the maximal vertical sizes were 22, 23, 22, and 23 mm at 10, 20, 30, and 40 W, respectively, with the 2-cm electrode. In the third experiment, the 18 G electrode had better water permeability than the 19 G electrode. In the fourth experiment, all pigs survived. Complications occurred in 1/5 (18 G electrode) and 4/7 (19 G electrode) pigs.
Conclusion: We performed EUS-RFA in pigs and concluded that it may be feasible to perform RFA of lesions near the stomach.
Keywords: Endoscopic ultrasonography; Liver; Radiofrequency ablation.