A system for cryoablating target tissue at a treatment site includes a cryo-element
mounted at the distal end of a cryo-catheter. A balloon catheter is provided having
a U-shaped balloon attached thereon. The cryo-element is threaded onto a pre-positioned
guidewire and advanced within the patient's vasculature until the cryo-element
is positioned at the treatment site. Next, the balloon is threaded onto the guidewire
and advanced within the patient's vasculature using the balloon catheter. At the
treatment site, the U-shaped balloon is interposed between the cryo-element and
the target tissue. Saline solution is pumped into the balloon causing the U-shaped
balloon to expand and contact both the cryo-element and the surrounding target
tissue. Next, a refrigerant is expanded to cool the cryo-element, which in turn,
freezes the saline solution. The resulting "ice ball" extracts heat from surrounding
tissue resulting in the cryoablation of a substantially circumferential portion
of tissue.
