Cleaning of occluded pancreatic duct endoprostheses: a new indication for extracorporeal shock wave lithotripsy?

Background Pancreatic duct stenting is widely performed for bridging main pancreatic duct obstruction in patients with chronic pancreatitis. The major limitation is early stent occlusion, making regular stent exchange necessary. Objective To date, no measures are available to prevent stent occlusion. The aim of this study was to evaluate the cleansing effect of shock wave application (SWA) on occluded pancreatic duct stents in vitro. Design In vitro study. Patients We analyzed occlusion rates of 25 plastic endoprostheses removed from 21 patients with chronic pancreatitis. Intervention We administered 350 shock wave pulses every 10 mm along the prosthesis, which was stored in a latex balloon filled with gas-free physiologic saline solution, by using a pressure of 42 megapascals. Main Outcome Measurements After SWA, the occlusion rate was measured again, and the cleansing rate was calculated in comparison with the native prosthesis. Results The mean (± SD) occlusion rate was significantly reduced (64.7 ± 28.7 [15%-100%]) before SWA vs 9.8 ± 25.3 [0-100%]) after SWA; P = .038). In 16 of 25 prostheses (64%), cleaning was complete. Four of the remaining 9 prostheses (16%) showed satisfactory cleaning of 95%, on average. Residual clogging material was found mainly at the duodenal tip and the middle of the stent. No significant association was found between patient-related or stent-related parameters and the cleansing effect of SWA. Limitations In vitro study design. Conclusion SWA is effective in cleaning occluded pancreatic endoprostheses in vitro. Prolongation of stent placement seems possible if regular SWA is performed. Extracorporeal shock wave lithotripsy therefore might become a new indication for patients under treatment with pancreatic endoprostheses.