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.