Abstract: A catheter is provided comprising a flexible heat transfer element provided on an outer surface of the catheter, a conduit arranged to supply an inflation fluid for inflating the flexible heat transfer element so as to form an inflated balloon, a guide wire lumen for receiving a guide wire, and an elongate cooling element arranged to cool said inflation fluid for inflating the balloon. Said cooling element and said guide wire lumen are arranged inside the flexible heat transfer element such that, when inflated the cooling element is substantially central within the balloon and said guide wire lumen is parallel to and radially offset from the cooling element.

Abstract: Disclosed herein is an apparatus for cooling a sterile liquid for use in cryotherapy, the apparatus comprising: a first chamber (202) adapted to receive a removable container (201) of sterile liquid and a fluid port for receiving a fluid for applying, in use, pressure to a received removable container (201); and a second chamber (203) comprising a cooler; wherein the first chamber (202) is arranged to be in thermal conductivity with the second chamber (203) such that, in use, the contents of the first chamber (202) are cooled by the cooler of the second chamber (203). Advantageously, embodiments provide a system, heat exchanger unit within the system and method for supplying a sterilised working fluid to a catheter system for cryotherapy, the working fluid being supplied at a desired and easily controllable temperature and flow rate.

Abstract: There is provided a method of supplying cryoenergy to a plaque within a blood vessel. The method comprises expanding an expandable membrane of a catheter apparatus with a pressure of less than 5 ATM (507 kPa), the catheter apparatus having been placed in thermal contact with the plaque within the blood vessel. The method also comprises establishing a temperature of between +15° C. (288K) and ?35° C. (238K) at an interface of the expandable membrane and the blood vessel. A system and catheter apparatus are also provided.