Percutaneous Endoluminal Radiofrequency Ablation of Occluded Biliary Metal Stent in Malignancy Using Monopolar Technique: A Feasibility Study

Abstract

Purpose

To prove feasibility and safety of percutaneous endoluminal radiofrequency ablation (eRFA) using a monopolar approach in treatment of occluded biliary stent in malignancy.

Materials and Methods

The study included 11 patients with occluded biliary metal stent that had been implanted due to malignant biliary obstruction. All underwent metal stent recanalization by percutaneous eRFA in monopolar setting. Sixteen eRFA procedures were performed under fluoroscopic guidance with an EndoHPB 8F radiofrequency ablation catheter. The effect of stent recanalization was assessed based upon change from pre- to post-procedural diameter of the patent lumen of the metal stent (Wilcoxon test), primary and secondary stent patency (compared by log-rank test), catheter-free period, and overall survival. Adverse events were evaluated according to Common Terminology Criteria for Adverse Events (CTCEA) 4.0.

Results

Recanalization of the metal stent by monopolar radiofrequency ablation was successful in all 11 patients. Diameter of the patent lumen of the stent significantly widened after the eRFA inside the stent (median 2 vs. 7 mm, p = 0.003). Grade 1 complications were observed in one-third of procedures. Median stent patency after recanalization by eRFA was non-inferior to primary metal stent patency (154 vs. 161 days, p = 0.27). Median catheter-free survival and overall survival after stent recanalization were 149 and 210 days, respectively.

Conclusion

Endoluminal radiofrequency ablation in monopolar setting was shown to be a feasible and safe method for recanalization of occluded biliary metal stents.

Level of evidence

Level 4, Case Series.

Appendices

Appendix A: Definitions and Monitored Parameters

Stenosis or occlusion of the metal stent was diagnosed based upon elevated obstructive liver enzymes, elevated bilirubin, and dilated bile ductus on imaging methods (ultrasound and CT), then finally confirmed by percutaneous cholangiography. Biliary metal stent patency after endobiliary recanalization by RFA was defined as the time until biochemical or clinical evidence of obstructive jaundice or the time until new or progressing biliary tract dilatation or death of the patient. Pre-procedural diameter of stenotic bile ducts in the stent was measured on cholangiogram after percutaneous puncture of bile ducts before passing the stenosis with a plastic drain. In the case of complete stent occlusion, diameter of 0 mm was recorded. Post-procedural diameter of the ablated bile duct was measured on cholangiogram 2 days after the last session of eRFA in two unidentical projections (e.g. anteroposterior and oblique views). The length of the stenosis was measured as the length of an irregular contour of the stenotic bile duct.

Appendix B: Detailed Description of the RF Ablation Procedure

The endpoint of each RF ablation procedure was to develop coagulative necrosis with charring. This was determined by rapid increase in impedance or reaching the maximum time of the RF ablation of 10 min at 10 W. If the ablation process did not lead to the intended result (i.e. increase in impedance), ablation in the same location was performed at 30 W for a maximum of 2 min. After each RF ablation, the catheter was removed, inspected for presence of debris and burnt tissue, then properly cleaned. Depending upon the length of the stricture, sequential applications of RF ablation were applied to ensure treatment of the full length of the stricture and with an overlap of treated areas. After the whole ablation procedure, balloon dilatation to clear the tumour fragments and debris was performed using a balloon of nominal diameter identical to the diameter of the stent. Patients underwent multiple sessions of ablation depending upon the evidence of successful recanalization on cholangiography. If there was no sign of restenosis on cholangiography at average 1 week after the last session of eRFA, external–internal drains were replaced by safety catheter. In the case of no clinical and laboratory deterioration, safety catheter was extracted after another week. In case of unsatisfactory cholangiography (i.e. persistent stent obstruction or in-stent stenosis 7 days after the initial procedure), eRFA was repeated.

It must be pointed out that when using the RITA 1500 generator, the distal electrode is active in the monopolar ablation. The proximal electrode is active when using the 1500X type (not investigated in the study).