Cryo-applicator cross-section configuration

Abstract

A configuration for a cryo-catheter which optimizes both the catheter's outer diameter and the size of the catheter's internal refrigerant flow path is described. Specifically, the inner dimensions of the cryo-catheter are configured to accommodate a pre-selected flow of refrigerant into the catheter's distal tip, and a return flow of refrigerant from the distal tip. The return flow is established in the void spaces between a refrigerant supply line and the inner wall of the catheter body. The available void space varies along the catheter length and depends on the presence/absence of various catheter accessories (i.e. pull wires, pressure tubes, etc.) which typically only extend through a portion of the catheter length. The disclosed configuration ensures that the cryo-catheter does not operate in a refrigerant limited condition, maintains the refrigerant as a liquid in the supply tube, and maintains the return line pressure at about 1 atmosphere.

What is claimed is: 
     
         1 . A configuration for cooling a medical device 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 coolant through said central lumen of said proximal segment and said distal segment to said tip;   wherein a return path for a flow of coolant 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.   
     
     
         2 . The configuration of  claim 1 , further comprising one or more accessory positioned in said central lumen. 
     
     
         3 . The configuration of  claim 2 , wherein the accessory positioned in said central lumen includes a steering element. 
     
     
         4 . The configuration of  claim 2 , wherein the accessory positioned in said central lumen includes a thermocouple wire. 
     
     
         5 . The configuration of  claim 2 , wherein the accessory positioned in said central lumen includes an electrode wire. 
     
     
         6 . 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.   
     
     
         7 . The configuration of  claim 6 , wherein said at least one accessory includes a pull wire. 
     
     
         8 . The configuration of  claim 6 , wherein said at least one accessory includes a thermocouple wire. 
     
     
         9 . The configuration of  claim 6 , wherein said at least one accessory includes an electrode wire. 
     
     
         10 . The configuration of  claim 6 , wherein said at least one accessory includes a pressure sensor. 
     
     
         11 . The configuration of  claim 6 , wherein said fluid supply means includes a hollow supply tube and a capillary tube. 
     
     
         12 . 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   
     
     
         13 . The catheter of  claim 12  wherein said at least one accessory includes a pull wire. 
     
     
         14 . The catheter of  claim 12  wherein said at least one accessory includes a thermocouple wire. 
     
     
         15 . The catheter of  claim 12  wherein said at least one accessory includes an electrode wire. 
     
     
         16 . The catheter of  claim 12  wherein said at least one accessory includes a pull wire, a thermocouple wire, and an electrode wire.