Integration of optical applicator with balloon catheter for photothermal treatment of biliary stricture

Background and Objective: Bile duct stricture is an uncommon disease in gastroenterology resulting from postoperative trauma. In spite of non-surgical treatments, clinical outcomes for the biliary strictures still encounter high restenosis and stent migration. The objective of the current study was to investigate the feasible application of a balloon catheter-integrated diffing applicator to thermally treat the bile duct stricture. Materials and Methods: 400-μm optical fibers were micro-machined and then integrated with an inflatable balloon catheter. The fabricated applicator was tested on porcine bile ducts with 20-W 980 nm laser light for 60 s, and a thermal camera was used to measure thermal response of the tissue. Due to mechanical pressure, the inflated balloon was able to expand the tissue lumen up to 6 mm in diameter. Results: Compared to control, the inner area of the treated tissue was increased by four fold (i.e., 2.74±0.05 mm2 for treated vs. 0.73±0.14 mm2 for control) during the balloon catheter-assisted laser irradiation. The laser-induced tissue temperature reached up to 80.1±6.4 °C (thermal gradient = 1.2 °C/s). A thin layer of coagulation necrosis (0.5±0.1 mm) consistently formed around the lumen. Conclusion: The proposed balloon catheter-integrated diffusing applicator can be a feasible minimally invasive device to photothermally treat the obstructive bile ducts. Lasers Surg. Med. 49:781–786, 2017.