Hyperthermia in the Treatment of Cholangiocarcinoma: Development and Testing of an Endobiliary Microwave Device

Purpose: The aim of this study was to create, perfect and test a hyperthermia balloon catheter for local treatment of cholangiocarcinoma. The device should induce hyperthermia in tumor tissue by acting locally in the bile duct lumen in contact with the tumor-infiltrated duct wall. In addition, it should exert tissue compression to cause an appreciable reduction in tumor microvasculature flow, thus improving thermal performance. Methods: According to the design specifications, the working temperature range should allow the device to be used for hyperthermia therapy either in combination with radiation and/or chemotherapy (radio/chemo-sensitizing effect at 42–45 °C) or alone (induction of coagulation necrosis above 65 °C). The balloon serves as an anchoring system during treatment and as a functional element to induce tissue compression. In vitro mechanical evaluation of the pressure/volume relationship, with the balloon inside rigid walled conduits, was performed. The heating shape around the catheter tip was determined by egg-white heating tests (coagulation at about 65 °C). Moreover, heating tests were carried out with explanted pig liver parenchyma. The temperature profile over time at different depths from the catheter axis was traced. Results: Three prototypes were manufactured. Mechanical functional tests showed that a 14 Fr deflated diameter balloon was suitable for bile duct diameters up to 11 mm. Thermal egg-white tests produced 4 cm long, 3 cm in diameter ellipsoidal heating figures in 30 min. In the biological tissue tests a coagulated area of similar geometry and comparable volume was produced. Conclusion: The results of tests confirm the device’s usefulness and versatility.