EUS-guided radiofrequency ablation with a prototype electrode array system in an animal model (with video)

BackgroundAlthough previously reported in an animal model, the development of EUS-guided radiofrequency ablation (EUS-RFA) has been impeded because of a lack of a retractable needle electrode array that could safely and effectively ablate large areas.ObjectiveTo evaluate the feasibility and safety of performing EUS-RFA with a 19-gauge FNA needle fitted with an umbrella-shaped retractable needle electrode array.Design and SettingEndoscopic experimental study in a porcine survival model at a tertiary referral center animal laboratory.Main Outcome MeasuresEvaluate the safety and efficacy of the retractable needle electrode array for performing EUS-RFA.InterventionsA 19-gauge EUS-FNA needle was modified and fitted with a retractable echogenic umbrella-shaped monopolar electrode array at its tip. The FNA needle was connected to a 200-W generator that has an impedance-based feedback system. EUS-RFA of the liver was attempted on 5 Yorkshire pigs. Although 1 pig was euthanized immediately after RFA to assess for immediate complications and pathological examination, the 4 others were kept alive for 7 days.ResultsAt EUS, the needle electrode was well visualized and could be deployed in the liver without technical difficulty. During ablation, a round hyperechoic focus gradually surrounded the electrode tip. Tissue ablation was attained within 7 minutes, and the electrode array could be easily withdrawn into the needle assembly. The vital signs of all pigs remained stable throughout the procedure and until they were euthanized. Histopathology in all pigs revealed a discrete, well-demarcated spherical focus of complete coagulation necrosis measuring 2.6 cm in diameter and without damage to the surrounding liver parenchyma or vasculature.ConclusionsIn this experimental study, EUS-RFA of the liver was performed safely by using the retractable umbrella-shaped electrode array with effective coagulation necrosis of large areas.