A method for controlling a balloon pressure of an inflatable balloon of an intravascular catheter system includes the steps of (i) sending sensor output to a controller, the sensor output being based at least partially on the balloon pressure, and (ii) maintaining the balloon pressure within a predetermined pressure range based at least partially upon the sensor output received by the controller. The step of maintaining includes one of (a) adjusting a flow rate of a cryogenic fluid through the inflatable balloon while moving the inflatable balloon from a first treatment site to a second treatment site, and (b) adjusting the flow rate of the cryogenic fluid that is selectively delivered from the fluid source to the inflatable balloon through an adjunct fluid injection line that is in fluid communication with a fluid exhaust line.
