Methods and apparatus for cryo-therapy

Abstract

Methods and apparatus for cryo-therapy are disclosed herein. This includes a hollow guidewire disposed within a catheter having helical loops contacting tissue. A coolant delivery tube disposed within can have a coolant delivered from a proximal end into the guidewire lumen. The coolant flows back proximally through the guidewire while cooling the guidewire surface and cooling or cryogenically ablating the contacting tissue. To minimize guidewire exposure to surrounding fluids or tissue, insulative barriers can be attached to the guidewire. A coolant delivery tube and return lumen can be integrated from a single extrusion in various configurations. Expandable balloons can also be used to expand the loops of the guidewire to contact the tissue. Also, helical loops with a coolant delivery tube or stem disposed longitudinally within the loops can be used and the loops can also have a variable collapsible cooling region.

I claim:  
     
         1 . An apparatus for thermally treating a hollow body organ comprising: 
 a catheter having a proximal end and a distal end and defining at least one lumen therebetween;    a guidewire defining at least one passageway therein, wherein the guidewire is configured to have a first configuration when disposed within the lumen and a second radially extended configuration when withdrawn from the lumen; and    a delivery tube disposable within the guidewire passageway for transporting a fluid, wherein the delivery tube defines at least one exit port near a distal end of the delivery tube through which the fluid passes.    
     
     
         2 . The apparatus of  claim 1  further comprising a cap disposed over a distal end of the guidewire.  
     
     
         3 . The apparatus of  claim 2  wherein the cap comprises a thermally conductive material.  
     
     
         4 . The apparatus of  claim 1  further comprising a membrane disposed along the guidewire passageway for containing a coolant flowing therethrough.  
     
     
         5 . The apparatus of  claim 1  further comprising a plurality of insulative barriers attached to an outer surface of the guidewire.  
     
     
         6 . The apparatus of  claim 1  further comprising an elongate control member having a proximal end and a distal end, wherein the distal end of the control member is attached to a distal end of the guidewire such that the guidewire is manipulatable along a longitudinal axis defined by the catheter via a proximal end of the elongate member.  
     
     
         7 . The apparatus of  claim 1  wherein the guidewire is configured to self-form from the first configuration to the second larger configuration.  
     
     
         8 . The apparatus of  claim 1  wherein the guidewire comprises a superelastic metal.  
     
     
         9 . The apparatus of  claim 1  wherein the second configuration comprises a plurality of helical loops configured to extend radially into contact with the hollow body organ.  
     
     
         10 . The apparatus of  claim 1  wherein the delivery tube defines a plurality of additional exit ports near the distal end.  
     
     
         11 . The apparatus of  claim 10  wherein each of the additional exit ports has a diameter which increases in size the farther distally the exit port is located.  
     
     
         12 . The apparatus of  claim 1  wherein the delivery tube further comprises a valve positioned at the exit port.  
     
     
         13 . The apparatus of  claim 1  wherein the delivery tube distal end is anchored at a distal end of the guidewire.  
     
     
         14 . The apparatus of  claim 1  wherein the delivery tube is integrally formed within the guidewire passageway.  
     
     
         15 . The apparatus of  claim 1  wherein the fluid comprises a liquid or gas coolant.  
     
     
         16 . The apparatus of  claim 15  wherein the fluid comprises a coolant selected from the group consisting of nitrogen, nitrous oxide, carbon dioxide, saline, fluorinated hydrocarbon, and chlorodifluoromethane.  
     
     
         17 . The apparatus of  claim 1  wherein the fluid is in a liquid phase in the delivery tube and in a gaseous phase when passed through the exit port.  
     
     
         18 . The apparatus of  claim 1  further comprising a pump in fluid communication with the delivery tube at a proximal end of the tube.  
     
     
         19 . An apparatus for thermally treating a hollow body organ comprising: 
 a catheter having a proximal end and a distal end and defining at least one lumen therebetween;    an expandable balloon attached to the distal end of the catheter, a surface of the balloon defining at least one helical passageway therein; and    a delivery tube disposable within the helical passageway for transporting a fluid, wherein the delivery tube defines at least one exit port near a distal end of the delivery tube through which the fluid passes.    
     
     
         20 . The apparatus of  claim 19  wherein the balloon defines a channel longitudinally therethrough when the balloon is in an expanded stated.  
     
     
         21 . The apparatus of  claim 19  wherein the delivery tube defines a plurality of additional exit ports near the distal end.  
     
     
         22 . The apparatus of  claim 21  wherein each of the additional exit ports has a diameter which increases in size the farther distally the exit port is located.  
     
     
         23 . The apparatus of  claim 19  wherein the fluid comprises a liquid or gas coolant.  
     
     
         24 . The apparatus of  claim 23  wherein the fluid comprises a coolant selected from the group consisting of nitrogen, nitrous oxide, carbon dioxide, saline, fluorinated hydrocarbon, and chlorodifluoromethane.  
     
     
         25 . The apparatus of  claim 19  wherein the fluid is in a liquid phase in the delivery tube and in a gaseous phase when passed through the exit port.  
     
     
         26 . The apparatus of  claim 19  further comprising a pump in fluid communication with the delivery tube at a proximal end of the tube.  
     
     
         27 . A method of thermally treating a hollow body organ comprising: 
 advancing a catheter within the hollow body organ to a region of tissue to be treated;    extruding a guidewire from the catheter and allowing the guidewire to radially extend into contact with the region of tissue, wherein the guidewire defines at least one passageway therein;    flowing a fluid through a delivery tube, wherein the tube is disposed within the passageway such that the fluid passes through at least one exit port defined near a distal end of the tube and flows within the passageway; and    thermally treating the region of tissue in contact with the guidewire via the fluid flowing within the passageway.    
     
     
         28 . The method of  claim 27  wherein the guidewire radially extends by self-forming from a first configuration into a pre-formed second larger configuration when extruded from the catheter.  
     
     
         29 . The method of  claim 27  wherein the guidewire is comprised of a superelastic metal.  
     
     
         30 . The method of  claim 28  wherein the second configuration comprises a plurality of helical loops.  
     
     
         31 . The method of  claim 30  wherein the guidewire is radially extended by an expandable balloon placed within the helical loops.  
     
     
         32 . The method of  claim 27  wherein the fluid comprises a liquid or gas coolant.  
     
     
         33 . The method of  claim 32  wherein the fluid comprises a coolant selected from the group consisting of nitrogen, nitrous oxide, carbon dioxide, saline, fluorinated hydrocarbon, and chlorodifluoromethane.  
     
     
         34 . The method of  claim 27  wherein the fluid is passed through a valve positioned at the exit port.  
     
     
         35 . The method of  claim 34  wherein the fluid is in a liquid phase in the delivery tube and in a gaseous phase when passed through the exit port.