Evaluation of bipolar radiofrequency ablation for occluded self-expandable metal stents in the bile duct: in vivo and in vitro study.

Abstract

Endobiliary radiofrequency ablation (RFA) has been used to treat occluded self-expandable metal stents (SEMSs). The aim of this study was to determine the characteristics of bipolar RFA in occluded SEMSs using both in vivo and in vitro models. For the in vivo study, uncovered SEMSs were deployed in the bile ducts of three pigs; another pig was used as the control. RFA was performed at 10 W for 90 seconds. The bile duct was examined for histological changes. For the in vitro simulation of tissue ingrowth in SEMSs, RFA at 10 W for 30 seconds was performed on SEMS-occlusion polyacrylamide-gel phantoms. The ablation depth was markedly reduced in the stented porcine bile duct. RFA of uncovered SEMS-occlusion gel phantoms resulted in early termination of RFA when the coagulated area contacted the SEMS. This phenomenon was not observed in RFA of the covered SEMS-occlusion gel phantoms. The presence of SEMSs attenuated the effect of bipolar endobiliary RFA. Tumorous tissue outside the SEMS is unlikely to be affected.