Cryoablation apparatuses, systems, and methods for renal neuromodulation

Abstract

Catheter apparatuses, systems, and methods for cryogenically modulating neural structures of the renal plexus by intravascular access are disclosed herein. One aspect of the present application, for example, is directed to apparatuses, systems, and methods that incorporate a catheter treatment device comprising an elongated shaft. The elongated shaft is sized and configured to deliver a cryo-applicator to a renal artery via an intravascular path. Cryogenic renal neuromodulation may be achieved via application of cryogenic temperatures to modulate neural fibers that contribute to renal function, or of vascular structures that feed or perfuse the neural fibers.

1 . A self-contained cryo-catheter system for cryo-ablating tissue of a renal artery, the cryo-catheter system comprising:
 an elongated shaft having a proximal end and a distal end, the proximal end configured to be coupled to a refrigerant source;   a handle positioned proximate to the proximal end of the elongated shaft;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising an expansion chamber;   a supply lumen located substantially within the elongated shaft, configured to receive a refrigerant from the refrigerant source, and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the refrigerant source and the expansion chamber;   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the expansion chamber to the proximal end; and   an actuator configured to control flow of the refrigerant.   
     
     
         2 . The cryo-catheter system of  claim 1 , further comprising a timer configured to limit the flow of refrigerant to no more than 2 minutes at a time. 
     
     
         3 . The cryo-catheter system of  claim 1  wherein the cryo-applicator is coupled to the distal end of the elongated shaft. 
     
     
         4 . The cryo-catheter system of  claim 1 , further comprising a refrigerant source, and wherein the refrigerant source is a pressurized container of less than about 20 grams of N 2 O. 
     
     
         5 . The cryo-catheter system of  claim 1  wherein the refrigerant is nitrous oxide, argon, carbon dioxide, chlorodifluoromethane, dichlorodifluoromethane, or dichlorotetrafluoromethane. 
     
     
         6 . The cryo-catheter system of  claim 1  wherein the cryo-catheter does not receive refrigerant from a cryo-console. 
     
     
         7 . The cryo-catheter system of  claim 1  wherein the refrigerant source is a cartridge or canister of N 2 O. 
     
     
         8 . The cryo-catheter system of  claim 1  wherein the handle is configured to receive the refrigerant source. 
     
     
         9 . The cryo-catheter system of  claim 1  wherein the cryo-catheter is not configured to connect to a separate cryo-console. 
     
     
         10 . The cryo-catheter system of  claim 1  wherein the cryo-catheter is disposed of after a single use. 
     
     
         11 . The cryo-catheter system of  claim 1  wherein the cryo-applicator is at least one of a metal tip, a balloon, a point ablate tip, an expandable loop, or an expandable metal structure. 
     
     
         12 . The cryo-catheter system of  claim 1  wherein the cryo-applicator is an inflatable balloon, and wherein the inflatable balloon in its inflated configuration has a length no more than about 15 mm and a diameter no more than about 10 mm. 
     
     
         13 . The cryo-catheter system of  claim 11  wherein the inflatable balloon in its inflated configuration has a length no more than about 8 mm. 
     
     
         14 . The cryo-catheter system of  claim 1 , further comprising a delivery sheath configured to provide intravascular access for the cryo-applicator to a renal artery. 
     
     
         15 . The cryo-catheter system of  claim 14  wherein the delivery sheath comprises an hollow tube with an outer diameter no greater than about 0.08″ and an inner diameter no greater than about 0.07″. 
     
     
         16 . The cryo-catheter system of  claim 14  wherein the delivery sheath comprises an hollow tube with an outer diameter no greater than about 0.105″ and an inner diameter no greater than about 0.091″. 
     
     
         17 . A cryo-catheter apparatus for cryo-ablating tissue of a renal artery, comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximal to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and an expansion chamber, wherein the cryo-applicator is provided as a metal tip;   a handle positioned proximate to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the expansion chamber and the proximal end;   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the expansion chamber;   wherein the cryo-catheter is configured to receive a refrigerant fluid from a source and deliver the refrigerant fluid via the supply lumen to the expansion chamber; and   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant fluid within the expansion chamber to cause cooling of the cryo-applicator.   
     
     
         18 . The cryo-catheter of  claim 17  wherein the metal tip comprises one or more of stainless steel, platinum, platinum iridium, or silver. 
     
     
         19 . The cryo-catheter of  claim 17  wherein the distal end of the elongated shaft is controllably deflectable. 
     
     
         20 . The cryo-catheter of  claim 19  wherein the cryo-catheter further comprises:
 a flexibly biased spine positioned in the distal end of the elongated shaft; 
 an deflection actuator disposed in the handle; and 
 a control wire having a distal end and a proximal end wherein the distal end is coupled to a distal end of the flexibly biased spine and the proximal end is coupled to the deflection actuator, 
 wherein the flexibly biased spine is configured to deflect upon actuation of the deflection actuator. 
 
     
     
         21 . The cryo-catheter of  claim 19  wherein the distal end of the elongated shaft in its fully deflected state has a radius of curvature no more than about 10 mm. 
     
     
         22 . The cryo-catheter of  claim 17  wherein the metal tip is less than or equal to about 3 mm long and less than or equal to about 0.06″ in diameter. 
     
     
         23 . The cryo-catheter of  claim 19  wherein the distal end of the elongated shaft has a maximally deflected state in which the metal tip is deflected no less than 5 mm and no more than 15 mm from a longitudinal axis of the elongated shaft. 
     
     
         24 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximal to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and an expansion chamber, wherein the cryo-applicator is configured to cryogenically ablate an elongated region within a renal artery;   a handle positioned proximal to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant fluid from a source and deliver the refrigerant fluid via the supply lumen to the cryo-applicator;   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant fluid within the expansion chamber to cause cooling of the cryo-applicator.   
     
     
         25 . The cryo-catheter of  claim 24  wherein the cryo-catheter comprises a restraining wire lumen which holds the cryo-applicator in a substantially linear configuration when a restraining wire is inserted into the restraining wire lumen. 
     
     
         26 . The cryo-catheter of  claim 25  wherein the cryo-applicator assumes a non-linear configuration when the restraining wire is at least partially removed. 
     
     
         27 . The cryo-catheter of  claim 26  wherein the non-linear configuration comprises at least one of a curved shape of a helix. 
     
     
         28 . The cryo-catheter of  claim 24  wherein the cryo-applicator is held in a substantially linear configuration when held within a delivery sheath. 
     
     
         29 . The cryo-catheter of  claim 28  wherein the cryo-applicator assumes a non-linear configuration when extended beyond the delivery sheath. 
     
     
         30 . The cryo-catheter of  claim 29  wherein the non-linear configuration comprises at least one of a curved shape of a helix. 
     
     
         31 . The cryo-catheter of  claim 24  wherein the cryo-catheter comprises a control wire and a flexibly biased spine. 
     
     
         32 . The cryo-catheter of  claim 24  wherein the cryo-applicator comprises two or more restriction orifices aimed in different directions so as to create different and discrete regions of cryogenic temperature on the cryo-applicator when refrigerant passes through the restriction orifices. 
     
     
         33 . The cryo-catheter of  claim 24  wherein the cryo-applicator comprises a polymer composition. 
     
     
         34 . The cryo-catheter of  claim 24  wherein the elongated region is no more than about 30 mm in length. 
     
     
         35 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and a looped structure of a tubular material, the looped structure at least in part defining an expansion chamber, wherein the looped structure begins at the restriction orifice and terminates at the exhaust lumen;   a handle positioned proximate to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle;   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant fluid from a source and deliver the refrigerant fluid via the supply lumen to the cryo-applicator; and   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant fluid within the expansion chamber to cause cooling of the cryo-applicator.   
     
     
         36 . The cryo-catheter of  claim 35  wherein the looped structure has a first configuration when held within a delivery sheath and a second, different configuration when extended beyond the delivery sheath. 
     
     
         37 . The cryo-catheter of  claim 35  wherein the closed loop structure is shaped as a substantially planar loop or as a helical structure. 
     
     
         38 . The cryo-catheter of  claim 35  wherein the closed loop structure forms a loop of about 4 mm to about 10 mm in diameter. 
     
     
         39 . The cryo-catheter of  claim 35  wherein the closed loop structure, when deployed, is generally perpendicular to the elongated shaft. 
     
     
         40 . The cryo-catheter of  claim 35  wherein the closed loop structure comprises a metallic or polymeric composition. 
     
     
         41 . The cryo-catheter of  claim 35  wherein the closed loop structure has an inner diameter of about 0.381 mm or greater. 
     
     
         42 . The cryo-catheter of  claim 35  wherein the closed loop structure is configured to make continuous contact against a wall of a renal artery. 
     
     
         43 . The cryo-catheter of  claim 35  wherein the closed loop structure is configured to make discontinuous contact against a wall of a renal artery. 
     
     
         44 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and a balloon connected to the distal end of the elongated shaft along a single opening;   a handle positioned proximate to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides from the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant fluid from a source and deliver the refrigerant fluid via the supply lumen to the cryo-applicator;   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant fluid within the balloon to cause cooling of the cryo-applicator.   
     
     
         45 . The cryo-catheter of  claim 44  wherein the balloon, when deployed, is not fully inflated. 
     
     
         46 . The cryo-catheter of  claim 44  wherein the balloon, when deployed, is occlusive. 
     
     
         47 . The cryo-catheter of  claim 44  wherein the cryo-applicator comprises a pressure sensor for measuring pressure within the balloon. 
     
     
         48 . The cryo-catheter of  claim 44  wherein the balloon becomes cold enough to cryogenically ablate tissue along its entire circumference when refrigerant flows through the one or more restriction orifices. 
     
     
         49 . The cryo-catheter of  claim 44  wherein the balloon becomes cold enough to cryogenically ablate tissue only at discrete points when refrigerant flows through the one or more restriction orifices. 
     
     
         50 . The cryo-catheter of  claim 49  wherein the discrete points are linearly and/or radially displaced from one another. 
     
     
         51 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and a balloon that does not occlude a renal artery when deployed;   a deflection mechanism configured to deflect the balloon against a vessel wall to achieve cryo-ablation at the site where the balloon contacts the vessel wall;   a handle positioned proximate to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant from a source and deliver the refrigerant via the supply lumen to the cryo-applicator;   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant within the balloon to cause cooling of the cryo-applicator.   
     
     
         52 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising two or more restriction orifices and one or more balloons connected to the distal end of the elongated shaft and configured to receive refrigerant from one or more of the restriction orifices;   a handle positioned proximate to the proximal end of the elongated shaft;   one or more supply lumens located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides from the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant from a source and deliver the refrigerant via the supply lumen to the cryo-applicator;   wherein the restriction orifices are configured to facilitate an endothermic expansion of the refrigerant within the one or more balloons to cause cooling of the cryo-applicator.   
     
     
         53 . The cryo-catheter of  claim 52 , further comprising two or more supply lumens such that different supply lumens supply refrigerant to different restriction orifices. 
     
     
         54 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, wherein the cryo-applicator comprises at least one restriction orifice and a metal tip that is biased to expand outward when not constrained;   a handle positioned proximate to the proximal end of the elongated shaft;   one or more supply lumens located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides from the removal of evaporated refrigerant from the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant from a source and deliver the refrigerant via the supply lumen to the cryo-applicator;   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant within the metal tip to cause cooling of the cryo-applicator.   
     
     
         55 . The cryo-catheter of  claim 54  wherein the metal tip comprises a metal tip that has a first diameter when constrained by a delivery sheath and a second, larger diameter when not constrained by a delivery sheath. 
     
     
         56 . The cryo-catheter of  claim 54  wherein the metal tip comprises one or more metal projections that are held against the remainder of the metal tip when surrounded by a delivery sheath. 
     
     
         57 . The cryo-catheter of  claim 55  wherein the one or more metal projections are configured to extend outward to contact a vessel wall when not surrounded by the delivery sheath. 
     
     
         58 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end, wherein the elongated shaft comprises at least two sections having different diameters;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and an expansion chamber;   a handle positioned proximate to the proximal end of the elongated shaft;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; and   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the cryo-applicator, and wherein a first portion of the exhaust lumen proximate to the handle has a greater cross-sectional area than a second portion of the exhaust lumen proximate to the cryo-applicator;   wherein the cryo-catheter is configured to receive a refrigerant from a source and deliver the refrigerant via the supply lumen to the cryo-applicator;   wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant within the expansion chamber to cause cooling of the cryo-applicator.   
     
     
         59 . The cryo-catheter of  claim 58  wherein the elongated shaft comprises a delivery section proximate to the handle and a deflectable section proximate to the cryo-applicator, wherein the delivery section is greater in diameter than the deflectable section. 
     
     
         60 . The cryo-catheter of  claim 59  wherein the delivery section comprises 90% or more of the length of the elongated shaft. 
     
     
         61 . The cryo-catheter of  claim 59  wherein the deflectable section comprises a length of between 2 cm and 10 cm. 
     
     
         62 . The cryo-catheter of  claim 61  wherein the deflectable section is configured for controllable deflection. 
     
     
         63 . A cryo-catheter apparatus for thermally ablating tissue, the cryo-catheter comprising:
 an elongated shaft having a proximal end and a distal end;   a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and an expansion chamber;   a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the expansion chamber and the proximal end;   an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides for the removal of evaporated refrigerant from the expansion chamber; and   at least one pre-cooling orifice formed within the supply lumen, wherein the pre-cooling orifice is proximal to the expansion chamber;   wherein the cryo-catheter is configured to receive a refrigerant from a source and deliver the refrigerant via the supply lumen to the expansion chamber and to the pre-cooling orifice.   
     
     
         64 . The cryo-catheter of  claim 63  wherein the at least one pre-cooling orifice is formed in the handle or in a portion of the elongated shaft proximal to the handle. 
     
     
         65 . The cryo-catheter of  claim 63  wherein the at least one pre-cooling orifice is formed in a portion of the elongated shaft that is not inserted into a patient. 
     
     
         66 . The cryo-catheter of  claim 63  wherein the at least one pre-cooling orifice comprises a smaller opening than the restriction orifice. 
     
     
         67 . The cryo-catheter of  claim 63 , further comprising a layer of insulation proximal to the cooling opening. 
     
     
         68 . A cryo-ablation system for thermally ablating tissue, the cryo-ablation system comprising:
 a cryo-catheter, comprising—
 an elongated shaft having a proximal end and a distal end; 
 a cryo-applicator positioned proximate to the distal end of the elongated shaft and configured for application of cryogenic temperatures, the cryo-applicator comprising at least one restriction orifice and an expansion chamber; 
 a handle positioned proximate to the proximal end of the elongated shaft; 
 a supply lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the supply lumen provides fluid communication between the cryo-applicator and the handle; 
 an exhaust lumen located substantially within the elongated shaft and extending along the elongated shaft, wherein the exhaust lumen provides from the removal of evaporated refrigerant from the cryo-applicator; 
 wherein the cryo-catheter is configured to receive a refrigerant fluid from a source and deliver the refrigerant fluid via the supply lumen to the cryo-applicator; 
 wherein the restriction orifice is configured to facilitate an endothermic expansion of the refrigerant fluid within the expansion chamber to cause cooling of the cryo-applicator; 
 a delivery sheath configured to surround the cryo-catheter such that a space exists between the interior surface of the delivery sheath and the exterior surface of the cryo-catheter; and 
 a cooling fluid supply configured to deliver a cooling fluid into the space between the cryo-catheter and the delivery sheath. 
   
     
     
         69 . The cryo-ablation system of  claim 68  wherein the cooling fluid is saline. 
     
     
         70 . The cryo-ablation system of  claim 68  wherein the delivery sheath comprises a flow limiter or seal to prevent or reduce the flow of cooling fluid into a patient. 
     
     
         71 . The cryo-ablation system of  claim 68 , further comprising a temperature sensor configured to provide a temperature measurement of the space to a controller configured to control the flow of the cooling fluid. 
     
     
         72 . The cryo-ablation system of  claim 68  wherein the cooling fluid is at about room temperature. 
     
     
         73 . The cryo-ablation system of  claim 68  wherein the cooling fluid is below room temperature. 
     
     
         74 . The cryo-catheter system of  claim 68 , further comprising a steerable guide catheter. 
     
     
         75 . A system for renal neuromodulation via cryoablation of renal nerves proximate to a renal artery of a patient, the system comprising:
 a cryocatheter comprising—
 an elongated shaft extending along an axis, the elongated shaft having a proximal end and a distal end; 
 a cryoapplicator positioned distal to the distal end of the elongated shaft and configured for endovascular delivery into the renal artery of the patient, the cryoapplicator comprising a restriction orifice and an expansion chamber; 
 a handle positioned proximal to the proximal end of the elongated shaft; 
 a supply lumen located substantially within the elongated shaft and extending along the axis of the elongated shaft, the supply lumen configured to put the cryoapplicator in fluid communication with the handle; and 
 an evacuation lumen located substantially within the elongated shaft and extending along the axis of the elongated shaft, the evacuation lumen configured to put the handle in fluid communication with the cryoapplicator, 
 wherein the cryocatheter is configured to receive a cryogenic fluid from a cryo source and deliver the cryogenic fluid via the supply lumen to the cryoapplicator under low pressure, 
 wherein the restriction orifice is configured to facilitate an endothermic expansion of the cryogenic fluid within the expansion chamber to cause cooling of the renal artery wall proximate to the cryoapplicator; and 
   a cryoconsole comprising a cryo source and a controller configured to operate instructions commanding the cryoconsole to deliver the cryogenic fluid to the cryocatheter.   
     
     
         76 . The system of  claim 75  wherein the cryo source comprises a canister containing cryogenic fluid. 
     
     
         77 . The system of  claim 75  wherein the cryoconsole comprises a handheld structure configured to be coupled with the handle of the cryocatheter. 
     
     
         78 . The system of  claim 77  wherein the handheld structure is fully disposable. 
     
     
         79 . The system of  claim 77  wherein the handheld structure is partially disposable. 
     
     
         80 . The system of  claim 77  wherein the handheld structure comprises a cartridge containing cryo fluid. 
     
     
         81 . The system of  claim 80  wherein the cartridge is disposable. 
     
     
         82 . The system of  claim 80  wherein the cartridge is reusable. 
     
     
         83 . The system of  claim 75  wherein the cryo source comprises liquid nitrous oxide. 
     
     
         84 . The system of  claim 75  wherein the controller is configured to regulate the delivery of cryo fluid based on feedback from the cryocatheter. 
     
     
         85 . The system of  claim 75  wherein the cryoconsole further comprises a vacuum configured to evacuate evaporated cryo fluid from the cryoapplicator of the cryocatheter at a back pressure that optimizes mass flow rate of the cryo fluid through the cryoapplicator while maintaining a cryo fluid boiling temperature of −60° C. or less. 
     
     
         86 . The system of  claim 75  wherein the controller is further configured to supply liquid cryo fluid to and evacuate evaporated cryo fluid from the cryoapplicator of the cryocatheter at a supply pressure, mass flow rate and back pressure sufficient to maintain a threshold temperature of the cryoapplicator while the cryoapplicator is in contact with a vessel wall of the renal artery for a predetermined contact period. 
     
     
         87 . The system of  claim 86  wherein the threshold temperature of the cryoapplicator is −80° C. or lower and the predetermined contact period is no greater than 120 seconds. 
     
     
         88 . The system of  claim 86  wherein the temperature of the cryoapplicator is −80° C. or lower and the predetermined contact period is no greater than 90 seconds. 
     
     
         89 . The system of  claim 86  wherein the temperature of the cryoapplicator is −80° C. or lower and the predetermined contact period is no greater than 60 seconds. 
     
     
         90 . The system of  claim 86  wherein the temperature of the cryoapplicator is −60° C. or lower but not less than −80° C. and the predetermined contact period is no greater than 150 seconds. 
     
     
         91 . A method for treating a patient diagnosed with at least one of hypertension, heart failure, chronic renal failure, end stage renal disease, acute myocardial infarction, contrast nephropathy, central sympathetic hyperactivity, insulin resistance, diabetes, metabolic syndrome via cryomodulation of renal nerves proximate a renal artery of the patient, the method comprising:
 endovascularly positioning the cryocatheter of example 1 within the renal artery of the patient;   facilitating contact between the cryoapplicator of the cryocatheter and an inner wall of the renal artery of the patient;   delivering a cryo fluid to the cryoapplicator in a manner to cause an endothermic evaporation of the cryo fluid at the cryoapplicator;   evacuating the evaporated cryo fluid from the cryoapplicator;   maintaining contact between the cryoapplicator and the vessel wall for a first predetermined time period, the first predetermined time period corresponding to when cryo fluid is actively delivered to the cryoapplicator;   maintaining contact between the cryoapplicator and the vessel wall for a second predetermined amount of time, the second predetermined time period corresponding to when cryo fluid is no longer actively delivered to the cryoapplicator; and   removing the cryoapplicator from the vessel wall following expiration of the second predetermined time period.   
     
     
         92 . The method of  claim 91  wherein removing the cryoapplicator from the vessel wall comprises repositioning the cryoapplicator to another part of the vessel wall for another treatment. 
     
     
         93 . The method of  claim 91  wherein removing the cryoapplicator from the vessel wall comprises removing the cryocatheter from the patient. 
     
     
         94 . A method of prospectively determining the results of a cryoablation treatment, the method comprising:
 positioning an intravascular cryoapplicator in a renal artery proximate to a renal nerve;   monitoring a physiologic parameter that is indicative of sympathetic renal nerve activity;   obtaining a first measure of the monitored physiologic parameter;   cooling a renal nerve to a temperature sufficient to temporarily disable the renal nerve;   obtaining a second measure of the monitored physiologic parameter, wherein the first measure is obtained prior to cooling and the second measure is obtained after cooling; and   comparing the first measure and the second measure to determine a change in sympathetic renal nerve activity.   
     
     
         95 . The method of  claim 94 , further comprising performing a challenge test known to promote a physiologic response mediated by renal nerves before and after cooling the renal nerve to a temperature sufficient to temporarily disable the renal nerve. 
     
     
         96 . The method of  claim 94  wherein the challenge test comprises at least one of:
 electrical stimulation of the renal nerve; and 
 infusion of a chemical agent into the renal artery. 
 
     
     
         97 . The method of  claim 94  wherein cooling a renal nerve to a temperature sufficient to temporarily disable the renal nerve comprises cooling the renal nerve to between about −20° C. and 0° C. 
     
     
         98 . The method of  claim 94  wherein monitoring a physiologic parameter that is indicative of sympathetic renal nerve activity comprises monitoring at least one of:
 renin level; and 
 renal epinephrine level.