Cryo-applicator cross-section configuration

A configuration for cooling a catheter shaft having a proximal end and a distal end, the configuration comprising:

• a tip at the distal end of said catheter;
• a handle at the proximal end of said catheter;
• an articulation segment attached to said tip;
• a proximal segment attached to said articulation segment and to said handle, wherein the proximal segment and the articulation segment define a central lumen extending between said handle and said tip, and wherein said central lumen has a first cross-sectional area in said articulation segment and a second cross-sectional area in said proximal segment, wherein said second cross-sectional area is greater than said first cross-sectional area;
• a fluid supply line for transferring a coolant through said central lumen of said proximal segment and said articulation segment to said tip;
• a return path for a flow of coolant defined in said central lumen by void space created between said fluid supply line and said catheter shaft, 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 articulation segment;
• and
• at least one accessory positioned in said central lumen spaced from each of the fluid supply line and the catheter shaft.

A cooled catheter having a proximal end and a distal end, the catheter comprising:

• a tip at the distal end of said catheter;
• a handle at the proximal end of said catheter;
• an articulation segment attached to said tip;
• a proximal segment attached to said articulation segment and to said handle, said articulation segment and said proximal segment defining a central lumen extending between said handle and said tip, and wherein said central lumen has a first cross-sectional area in said articulation segment and a second cross-sectional area in said proximal segment, wherein said second cross-sectional area is greater than said first cross-sectional area;
• a fluid supply configured to provide a coolant through said central lumen to said tip;
• a return path for a flow of coolant defined in said central lumen by a void space created between said fluid supply and a wall of the catheter, wherein the return path includes a first void space in the proximal segment that is greater in cross-sectional area than a second void space in the articulation segment;
• and
• at least one accessory positioned in said central lumen and spaced from each of the fluid supply and catheter shaft