Abstract: Apparatus, consisting of a probe with a probe distal end having an external surface that contacts tissue when the distal end is inserted into a patient. A heater and a temperature sensor are in the distal end, and a gas inlet is coupled to the distal end to provide gas. While the heater is activated, a controller registers a first time when a temperature measured by the sensor equals or exceeds a preset temperature, and, in response to the temperature equaling or exceeding the preset temperature, delivers a gas pulse through the gas inlet so as to cool the probe distal end. The controller then registers a second time when the temperature measured by the sensor equals or exceeds the preset temperature, and, in response to a time difference between the second and first times, estimates a temperature of the external surface of the probe distal end.

Abstract: Cryogenic apparatus, consisting of a connector that has a connector base plate configured for connection to a conduit carrying a cryogen, and a slot extending across the base plate. The apparatus has a plug, which is configured for insertion into an opening in the base plate. The apparatus also has a latch plate that is configured to slide within the slot between a first position, in which the plug is inserted through an aperture in the latch plate into the opening, and a second position, in which a cryogenic probe is inserted through the aperture and brought into fluid communication with the opening. There is a sensor, which is coupled to control a flow of the cryogen through the conduit by detecting whether the latch plate is in the first position or the second position.

Abstract: Cryogenic apparatus, consisting of a connector that has a connector base plate configured for connection to a conduit carrying a cryogen, and a slot extending across the base plate. The apparatus has a plug, which is configured for insertion into an opening in the base plate. The apparatus also has a latch plate that is configured to slide within the slot between a first position, in which the plug is inserted through an aperture in the latch plate into the opening, and a second position, in which a cryogenic probe is inserted through the aperture and brought into fluid communication with the opening. There is a sensor, which is coupled to control a flow of the cryogen through the conduit by detecting whether the latch plate is in the first position or the second position.