The present invention advantageously provides a method and
system for cryogenically ablating large areas of tissue within the
left atrium. In an exemplary embodiment a
cryotherapy device includes a
catheter body having a substantially fixed
diameter, a proximal end and a distal end; a first lumen for permitting passage of a
cooling fluid from the proximal end to the distal end; a second lumen permitting return of the
cooling fluid from the distal end to the proximal end; and an
ablation element expandable from a first
diameter that is substantially the same as the
diameter of the
catheter body to a second diameter that is at least twice the diameter of the
catheter body, the
ablation element having a surface portion that conforms to the uneven surface
topography of the cardiac tissue. The
ablation element can include one or more
balloon and / or a flexible element that is deformed by moving the distal end of the catheter toward the proximal end of the catheter. The surface of the
balloon can further be shaped by regulation of pressure within the one or more balloons. In an exemplary method a
tissue ablation device is provided and tissue in the
antrum of the
left atrium is ablated with the device. In an exemplary method, only tissue in the
antrum is ablated, and the ablation is created by freezing tissue.