Abstract: A flexible catheter is inserted into the esophagus to cool or warm the esophagus, particularly during certain procedures which can tend to change the temperature in the area of the esophagus. The catheter is inserted through the mouth and throat to a position, for example, proximate the heart, but within the esophagus. One or more balloons are inflated to block areas of the esophagus, while a gel is injected into the esophagus where it is immobilized by the one or more balloons. A coolant is pumped through a coolant tube affixed to the catheter, where it exchanges heat with the conductive gel.