Abstract: This specification describes a tissue ablation apparatus comprising a catheter configured to enter an internal region of a subject's body, and a cooling device configured to cool internal tissue to a desired temperature of between ?15 degrees C. and +15 degrees C.

Abstract: A cooling device for cooling a subject's tissue or organ surface, the device comprising a handle and a head. The head comprises an electrical cooling element for cooling the subject's tissue or organ surface. The device also comprises a controller configured to: receive the initial temperature of the subject's tissue or organ surface; determine a cooling temperature based on the initial temperature of the subject's tissue or organ surface and a target temperature; and control the cooling element to generate the cooling temperature. The invention also provides a separate head and handle. The invention also provides a method of controlling the cooling device.