Sa1440 Presence of Metal Stent in Porcine Bile Duct Attenuates the Effect of Radiofrequency Ablation: Results of a Pilot Study

Abstract

Sa1440 Presence of Metal Stent in Porcine Bile Duct Attenuates the Effect of Radiofrequency Ablation: Results of a Pilot Study Won Jae Yoon*, Ebubekir S. Daglilar, Mari Mino-Kenudson, William R. Brugge Gastrointestinal Unit, Massachusetts General Hospital, Boston, MA; Pathology, Massachusetts General Hospital, Boston, MA Background: Endoscopically applied biliary radiofrequency ablation (RFA) in patients with unresectable malignant biliary stenosis has shown promising results. RFA may re-establish patency of occluded metal biliary stents. We have shown that application of RFA at 10 W for 90 seconds in the porcine bile duct results in transmural tissue ablation. However, there is little data on RFA in the bile duct containing a metal stent. Aims: The aims of this study were to determine the feasibility and performance characteristics of biliary RFA in the stented porcine bile duct. Methods: Four farm pigs weighing 40-50 kg were used for this study. Under general anesthesia and a laparotomy, a duodenotomy was performed. After identification of the bile duct opening, a 10-mm X 6-cm uncovered metal biliary stent (Zilver® stent, Cook Medical, Winston-Salem, NC) was deployed in 3 pigs; the stent was not deployed in 1 pig, serving as a control. The biliary bipolar RFA catheter (HabibTM EndoHPB catheter, EMcision Ltd., London, UK) was introduced through the stent lumen or the bile duct lumen. In the stented bile duct, RFA was applied at 10 W for 90 seconds, with a range of voltages among pigs (66 V [n 1], 132 V [n 1], and 190 V [n 1]). In the control bile duct (n 1), RFA was applied at 10 W and 190 V for 90 seconds. After the RFA, the pigs were euthanized and necropsied. The bile duct was examined for histological changes. Results: The retrograde insertion of the biliary RFA catheter through the metal stent or the bile duct orifice was easily achieved. Grossly, the ablated area was distributed only along the area adjacent to the electrodes of the RFA probe. In the unstented bile duct, RFA resulted in transmural ablation of the bile duct wall (Figure 1A). However, in the stented bile duct, the depth of ablation was reduced compared to the unstented bile duct. In detail, at 66 V (Figure 1B) and 132 V (Figure 1C), the ablation was limited to the superficial mucosa with no effect on the glands. At 190 V (Figure 1D), the ablation of the superficial mucosa including the superficial glands was noted. Conclusions: Biliary RFA through a metal stent seems technically feasible. However, at 10 W, biliary RFA was markedly attenuated by the presence of a metal stent. A greater power is probably needed to achieve deep ablation.