Cryosurgical devices and methods for endometrial ablation

Abstract

A cryoablation system including a cannula having a proximal end, a distal end, and a longitudinal axis, an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source. The heat exchanger may be positioned within the probe handle, within the cannula, or at least partially within the balloon. The heat transfer fluid of this cryoablation system preferably has a freezing point lower than about −110° C. and a boiling point greater than about 50° C.

1 . A cryoablation system for performing endometrial ablation, comprising:
 an elongated tubular cannula having a proximal end, a distal end, and a longitudinal axis;   an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path;   a pump for circulating the heat transfer fluid into and out of the balloon;   a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula; and   a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source.   
     
     
         2 . The cryoablation system of  claim 1 , wherein the balloon is expandable in response to an addition of a volume of heat transfer fluid. 
     
     
         3 . The cryoablation system of  claim 1 , wherein the heat exchanger is positioned within the probe handle so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the heat transfer fluid is provided to the balloon. 
     
     
         4 . The cryoablation system of  claim 1 , wherein the heat exchanger is positioned within the cannula so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the heat transfer fluid is provided to the balloon. 
     
     
         5 . The cryoablation system of  claim 1 , wherein the heat exchanger is positioned within a console of the system so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the fluid is provided to the probe handle. 
     
     
         6 . The cryoablation system of  claim 1 , wherein the heat exchanger is positioned at least partially within the balloon. 
     
     
         7 . The cryoablation system of  claim 1 , wherein the heat transfer fluid has a freezing point lower than about −110° C. and a boiling point greater than about 50° C. 
     
     
         8 . The cryoablation system of  claim 7 , wherein the heat transfer fluid has a freezing point lower than about −130° C. and a boiling point greater than about 60° C. 
     
     
         9 . The cryoablation system of  claim 1 , wherein the heat transfer fluid has a boiling point greater than the operating temperature of the system so that the heat transfer fluid does not vaporize during or after operation of the system. 
     
     
         10 . The cryoablation system of  claim 1 , further comprising a sheath that at least partially surrounds the cannula and that extends along at least a portion of a length of the cannula. 
     
     
         11 . The cryoablation system of  claim 10 , wherein the sheath is moveable along the longitudinal axis of the cannula relative to the balloon. 
     
     
         12 . The cryoablation system of  claim 11 , wherein the sheath is partially retractable relative to the balloon to allow for inflation of the balloon. 
     
     
         13 . The cryoablation system of  claim 1 , wherein the probe handle is removeably coupled to the proximal end of the cannula. 
     
     
         14 . The cryoablation system of  claim 1 , further comprising a coupling for coupling of the probe handle to the proximal end of the cannula, wherein the coupling comprises a mechanism for sealing the fluid circuits of the system from the ambient environment. 
     
     
         15 . A method of performing endometrial ablation, comprising the steps of:
 providing a cryoablation system comprising a tubular cannula having a proximal end and a distal end, a balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid through the cannula, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle extending from the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid;   inserting the balloon in a collapsed state into the uterus of a patient;   inflating the balloon with a volume of the heat transfer fluid at a first temperature until it reaches a predetermined size;   cooling the heat transfer fluid with the heat exchanger to lower its temperature from first temperature to a desired treatment temperature;   maintaining the balloon position within the uterus for a therapeutic time period;   deflating the balloon until the balloon is sufficiently small to allow for its removal from the uterus; and   removing the balloon from the uterus.   
     
     
         16 . The method of  claim 15 , wherein the cryoablation system further includes a sheath at least partially containing the balloon in a compressed condition during the insertion step, and wherein the method further comprises moving the sheath relative to the cannula to deploy the balloon after insertion of the balloon into the uterus of the patient. 
     
     
         17 . The method of  claim 15 , further including the step of warming the heat transfer fluid from its treatment temperature until the balloon is free from the uterine walls. 
     
     
         18 . The method of  claim 15 , wherein the treatment temperature of the heat transfer fluid is between the freezing point and the boiling point of the heat transfer fluid.