Patent ID: 8377050

Claim:
A configuration for a cryo-applicator having a proximal end and a distal end, the configuration comprising: a catheter shaft including a distal segment having a distal end and a proximal end, a tip at the distal end of said distal segment, and a proximal segment attached to said distal segment, wherein said proximal segment and said distal segment define a central lumen extending through at least a portion of said catheter shaft, wherein said central lumen has a first cross-sectional area in said distal segment and a second cross-sectional area in said proximal segment, wherein the second cross-sectional area of the proximal segment is greater the first cross-sectional area; and a fluid supply line for transferring a liquid refrigerant through said central lumen of said proximal segment and said distal segment to said tip for boiling the liquid refrigerant in said tip; wherein a return path for a flow of gaseous refrigerant is defined in said central lumen by a void created between said fluid supply line and said catheter shaft, and further wherein the return path includes a first void space in the proximal segment that is at least about 30% greater in cross-sectional area than a second void space in the distal segment such that a pressure in the return path is substantially equal to a pressure in the tip when the applicator is in use such that the liquid refrigerant is maintained in a liquid state as it flows through the fluid supply line.