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Aspiring to inspIRE: catheter-directed electrical therapy and biliary metal stent patency

      Abbreviations:

      CBD (common bile duct), IRE (irreversible electroporation), RFA (radiofrequency ablation), SEMS (self-expandable metallic stent)
      In the January issue of Gastrointestinal Endoscopy, Ueshima et al
      • Ueshima E.
      • Schattner M.
      • Mendelsohn R.
      • et al.
      Transmural ablation of the normal porcine common bile duct with catheter-directed irreversible electroporation is feasible and does not impact duct patency.
      describe the feasibility and safety of catheter-directed irreversible electroporation (IRE) of a normal common bile duct (CBD) in an animal model. The authors report the results of their initial experience with a novel catheter (20 mm long, 7F) using a modified 240-cm balloon dilation catheter, which serves as a monopolar device to perform direct IRE at 2000 V, 90 pulses, and 100-μs pulse. On the basis of these preliminary results. intraluminal catheter-directed IRE is feasible and safe for the full-thickness ablation of the normal porcine CBD without affecting lumen patency up to 1 week after treatment.
      During the past several decades, ERCP together with placement of a plastic or metal biliary stent (SEMS) has become the treatment of choice as a bridge for surgery or as palliative treatment for patients with pancreatic or biliary malignancy. At present there are several subtypes of metal stents within the 2 main groups of covered and uncovered metal stents. Covered stents may be coated with silicone, polycaprolactone, polyether polyurethane, polyurethane, or expanded polytetrafluoroethylene fluorinated ethylene propylene. All are similarly effective.
      • Yoon W.J.
      • Lee J.K.
      • Lee K.H.
      • et al.
      A comparison of covered and uncovered Wallstents for the management of distal malignant biliary obstruction.
      • Ornellas L.C.
      • Stefanidis G.
      • Chuttani R.
      • et al.
      Covered Wallstents for palliation of malignant biliary obstruction: primary stent placement versus reintervention.
      Stent obstruction, however, is one of the most frequent challenges in patients with biliary or pancreatic malignancy. Different factors such as tumor ingrowth, tumor overgrowth, regenerative changes leading to nonmalignant tissue ingrowth, sludge, and biliary stone fragments play a role in the etiology of biliary stent occlusion.
      It is well known that metal stents have longer patency and survival when compared with plastic biliary stents.
      • Perdue D.G.
      • Freeman M.L.
      • DiSario J.A.
      • et al.
      Plastic versus self-expanding metallic stents for malignant hilar biliary obstruction: a prospective multicenter observational cohort study.
      • Peters R.A.
      • Williams S.G.
      • Lombard M.
      • et al.
      The management of high-grade hilar strictures by endoscopic insertion of self-expanding metal endoprostheses.
      Early reports by Wagner et al
      • Wagner H.J.
      • Knyrim K.
      • Vakil N.
      • et al.
      Plastic endoprostheses versus metal stents in the palliative treatment of malignant hilar biliary obstruction: a prospective and randomized trial.
      showed higher long-term stent failure in patients who underwent ERCP with plastic stent placement than in patients who underwent SEMS placement during ERCP (50% vs 18%). Sangchan et al
      • Sangchan A.
      • Kongkasame W.
      • Pugkhem A.
      • et al.
      Efficacy of metal and plastic stents in unresectable complex hilar cholangiocarcinoma: a randomized controlled trial.
      published a randomized control trial of 108 patients with unresectable biliary malignancy and were able to show that patients who underwent SEMS placement during ERCP had higher rate of effective drainage and fewer cholangitis events, which resulted in a better prognosis. Numerous studies have shown no superiority of covered metal stents when compared with uncovered metal stents in biliary obstruction.
      • Kahaleh M.
      • Tokar J.
      • Conaway M.R.
      • et al.
      Efficacy and complications of covered Wallstents in malignant distal biliary obstruction.
      • Kahaleh M.
      • Brock A.
      • Conaway M.R.
      • et al.
      Covered self-expandable metal stents in pancreatic malignancy regardless of resectability: a new concept validated by a decision analysis.
      In a recent meta-analysis, Almadi et al
      • Almadi M.A.
      • Barkun A.N.
      • Martel M.
      No benefit of covered vs uncovered self-expandable metal stents in patients with malignant distal biliary obstruction: a meta-analysis.
      compared covered with uncovered stents and showed similar stent patency at 6 and 12 months, with odds ratio (OR)1.8; 95% confidence interval (CI), 0.63-5.3; and OR 1.3; 95% CI, 0.65-2.4, respectively.
      • Almadi M.A.
      • Barkun A.N.
      • Martel M.
      No benefit of covered vs uncovered self-expandable metal stents in patients with malignant distal biliary obstruction: a meta-analysis.
      Despite multiple adverse events such as stent migration, acute cholecystitis, cholangitis, and bleeding, stent occlusion remains one of the greatest clinical challenges in managing biliary obstruction after SEMS placement, and thus methods to increase stent patency are highly desirable. Steel et al
      • Steel A.W.
      • Postgate A.J.
      • Khorsandi S.
      • et al.
      Endoscopically applied radiofrequency appears to be safe in the treatment of malignant biliary obstruction.
      showed that radiofrequency ablation (RFA) with the use of endoscopy may increase stent patency, but owing to its thermal mechanism, RFA may also provoke biliary perforation and cholangitis.
      • Steel A.W.
      • Postgate A.J.
      • Khorsandi S.
      • et al.
      Endoscopically applied radiofrequency appears to be safe in the treatment of malignant biliary obstruction.
      Alternatively, by the use of submillisecond-long electric pulses alternating the transmembrane potential of cells, which induces pore formation leading to cell death whereas the extracellular matrix is undamaged, percutaneous irreversible electroporation (IRE) may represent a method to achieve longer stent patency and survival by decreasing cholangitis events without an increased risk for biliary perforation.
      • Ueshima E.
      • Schattner M.
      • Mendelsohn R.
      • et al.
      Transmural ablation of the normal porcine common bile duct with catheter-directed irreversible electroporation is feasible and does not impact duct patency.
      Although the results of this current study are promising, further investigations using IRE are required in a move from preclinical to clinical studies.

      Disclosure

      All authors disclosed no financial relationships relevant to this publication.

      References

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