Heat exchanger unit for cryotherapy

An apparatus for supplying a sterile liquid to a catheter for use in cryotherapy, the apparatus comprising:

• a container for containing a sterile liquid;
• a first chamber adapted to receive the container, the container being removable from the first chamber when the container contains the sterile liquid, the first chamber further comprising a fluid port for receiving a surrounding fluid for applying, in use, pressure to the received container;
• and
• a second chamber comprising a cooler;
• wherein the first chamber is arranged to be in thermal conductivity with the second chamber such that, in use, the contents of the first chamber are cooled by the cooler of the second chamber;
• the apparatus further comprising a conduit for providing a supply of the surrounding fluid to the fluid port of the first chamber, wherein the conduit passes through the second chamber and the conduit is arranged in coils in the second chamber.