Devices and methods for cooling vessel walls to inhibit 
restenosis in conjunction with medical procedures such as coronary 
artery angioplasty. Stenosed vessel walls can be cooled prior to 
angioplasty, after 
angioplasty, or both. The invention is believed to inhibit 
restenosis through cooling to a temperature near freezing, preferably without causing substantial vessel wall 
cell death. One 
catheter device includes a distal tube region having 
coolant delivery holes radially and longitudinally distributed along the distal region. In some devices, holes spray 
coolant directly onto the vessel walls, with the 
coolant absorbed into the 
blood stream. In other embodiments, a 
balloon or envelope is interposed between the coolant and the vessel walls and the coolant returned out of the 
catheter through a coolant return lumen. Some direct spray devices include an 
occlusion device to 
restrict blood flow past the region being cooled. Pressure, temperature, and ultrasonic probes are included in some cooling catheters. 
Pressure control valves are included in some devices to regulate 
balloon interior pressure within acceptable limits. In applications using 
liquid carbon dioxide as coolant, the 
balloon interior pressure can be maintained above the 
triple point of 
carbon dioxide to inhibit 
dry ice formation. Some cooling catheters are coiled 
perfusion catheters supporting longer cooling periods by allowing perfusing 
blood flow simultaneously with vessel wall cooling. One coiled 
catheter is biased to assume a coiled shape when unconstrained and can be introduced into the body in a relatively straight shape, having a stiffening wire inserted through the coil strands.