Devices, systems, and methods controllably cool blood vessels and other
body lumens. The blood vessel will often be treated for atherosclerotic
or other diseases by inflating a balloon so as to engage the surrounding
luminal wall. Controlled cooling of the balloon effected by a change in
phase of a cryogenic fluid within the balloon typically a change from a
liquid phase to a gas phase can be provided with a controlled, gradual
inflation of the balloon. A single control system can be used for any of
a variety of alternative selectable balloon catheters having
significantly differing cooling fluid flow characteristics.