Patent attributes
Apparatus, consisting of a probe, containing a lumen and having a distal end configured to contact tissue of a living subject. A temperature sensor is located at the distal end, and a pump, having a pump motor, is coupled to deliver a cryogenic fluid through the lumen to the distal end of the probe and to receive the cryogenic fluid returning from the probe. There is a separator, coupled to separate the returning cryogenic fluid into a returning cryogenic liquid and a returning cryogenic gas, and a flow meter, coupled to measure a rate of flow of the returning cryogenic gas. A processor is configured to control a rate of pumping of the pump motor in response to a temperature measured by the temperature sensor and the rate of flow of the returning cryogenic gas.
