Abstract: A sheath for use on a closed loop Joule-Thomson cryosurgical probe, and the combination of the and the closed loop probe. The sheath is slipped over the probe, thereby separating the probe from the environment. The sheath has a grip which fits over the handle of the cryosurgical probe, and an extendible shroud which can be longitudinally extended to cover tubing and which are attached to the handle. The sheath has a hollow multi-lumen catheter shaped and sized to fit snugly over the cannula of the cryosurgical probe. The catheter is not thermally conductive, preventing transfer of heat from the ambient to the gas mixture, and preventing the freezing of tissues at undesired locations along the catheter. A thermally conductive cap or tip is attached to the distal end of the hollow catheter. The thermally conductive cap or tip fits snugly over the cold tip on the probe, and it efficiently transfers heat from the target tissue to the cold tip, which in turn transfers heat to the expanded gas mixture.

Abstract: A cryosurgical probe incorporating various forms of auxiliary instrumentation mounted on the catheter or conductive tip, such as a temperature sensor, a heater, an ultrasonic transducer, or an optical element of a viewing, illumination, or laser system, and a method for employing such a probe for ablation of uterine tissue.

Abstract: A miniature mixed gas refrigeration system is disclosed, having a coaxial catheter with an inner high pressure supply lumen and an outer low pressure return lumen. The gas mixture is pressurized by a compressor to a pressure less than 420 psia, for safety reasons. The distal portion of the outer lumen contains a micro-miniature heat exchanger constructed of laminated plates or sheets. The plates or sheets establish high pressure and low pressure passageways, with high surface area, having a tortuous path for the gas flow to maximize heat exchange. The high pressure outlet of the heat exchanger is connected to a Joule-Thomson expansion element where the high pressure gas is expanded isenthalpically to a lower temperature at least as low as 180K. This low temperature gas cools a heat transfer element mounted in the outer wall of the catheter, to cool an external object. Return gas flows back through the heat exchanger to pre-cool the incoming high pressure gas mixture.

Abstract: A method for performing hypothermia of a selected organ without significant effect on surrounding organs or other tissues. A flexible coaxial catheter is inserted through the vascular system of a patient to place the distal tip of the catheter in an artery feeding the selected organ. A chilled perfluorocarbon fluid is pumped through an insulated inner supply conduit of the catheter to cool a flexible bellows shaped heat transfer element in the distal tip of the catheter. The heat transfer bellows cools the blood flowing through the artery, to cool the selected organ, distal to the tip of the catheter.

Abstract: A heat transfer device has first and second elongated, articulated segments, each having a turbulence-inducing exterior surface. A flexible joint connects the first and second elongated, articulated segments. An inner coaxial lumen is disposed within the first and second elongated, articulated segments. The inner coaxial lumen is capable of transporting a pressurized working fluid to a distal end of the first elongated, articulated segment.

Abstract: A miniature refrigeration system and method of operation. A primary refrigerant is pressurized by a compressor to a relatively low pressure, for safety reasons. The compressed primary refrigerant is passed through a primary-to-secondary heat exchanger, to precool the gas mixture. The secondary side of the primary-to-secondary heat exchanger is cooled by a secondary refrigeration system. The primary refrigerant exiting the primary outlet of the primary-to-secondary heat exchanger passes to a primary Joule-Thomson expansion element where the high pressure gas is expanded to a lower temperature. This low temperature gas cools a heat transfer element mounted in the outer wall of the catheter or cryoprobe, to cool surrounding tissue. Return gas can flow back through a distal primary-to-primary heat exchanger to further cool the incoming high pressure gas mixture. A proximal primary-to-primary heat exchanger can be added between the primary-to-secondary heat exchanger and the primary compressor.

Abstract: A method and apparatus for performing hypothermia of a selected organ without significant effect on surrounding organs or other tissues. A flexible catheter is inserted through the vascular system of a patient to place the distal tip of the catheter in an artery feeding the selected organ. A compressed refrigerant is pumped through the catheter to an expansion element near the distal tip of the catheter, where the refrigerant vaporizes and expands to cool a flexible heat transfer element in the distal tip of the catheter. The heat transfer element cools the blood flowing through the artery, to cool the selected organ, distal to the tip of the catheter.

Abstract: A method and apparatus for performing hypothermia of a selected organ without significant effect on surrounding organs or other tissues, by perfusion of the organ with blood cooled externally from the body of the patient. A flexible supply catheter is inserted percutaneously into an artery. Blood from the supply catheter is cooled in a finned tube heat exchanger or a fluid bath. A flexible delivery catheter is inserted percutaneously through the vascular system of the patient to place the distal end of the catheter in an artery feeding the selected organ. An occlusion device is expanded to occlude the feeder artery at a point proximal to the distal end of the delivery catheter. Cooled blood from the chiller is pumped through the delivery catheter to an outlet near the distal end of the catheter, to cool the selected organ, distal to the tip of the delivery catheter.

Abstract: A microminiature laminated heat exchanger for use in a cryogenic probe, and a method of manufacture. The heat exchanger has high and low pressure flow patterns etched into oxygen free copper sheets, with the flow patterns being tortuous paths promoting turbulent flow. The sheets containing the flow patterns are bonded into a laminated assembly in the shape of a cylinder, with a high pressure inlet and a low pressure outlet in a first end, and a high pressure outlet and a low pressure inlet in a second end. The high pressure flow path lies alongside the low pressure flow path, with flow in the two paths being in opposite directions, to accomplish counterflow heat exchange.

Abstract: A miniature mixed gas refrigeration system and method of operation are disclosed, having a coaxial catheter with an inner high pressure supply lumen and an outer low pressure return lumen. An optimum gas mixture is formulated from a group of component fluids, according to calculated thermodynamic properties of a group of candidate fluid mixtures. The gas mixture is pressurized by a compressor to a pressure less than 420 psia, for safety reasons. The distal portion of the outer lumen contains a micro-miniature heat exchanger constructed of laminated plates or sheets. The plates or sheets establish high pressure and low pressure passageways, with high surface area, having a tortuous path for the gas flow to maximize heat exchange. The high pressure outlet of the heat exchanger is connected to a Joule-Thomson expansion element where the high pressure gas is expanded isenthalpically to a lower temperature at least as low as 183K.

Abstract: A method and apparatus for performing hypothermia of a selected organ without significant effect on surrounding organs or other tissues. A flexible catheter is inserted through the vascular system of a patient to place the distal tip of the catheter in an artery feeding the selected organ. A compressed refrigerant is pumped through the catheter to an expansion element near the distal tip of the catheter, where the refrigerant vaporizes and expands to cool a flexible bellows shaped heat transfer element in the distal tip of the catheter. The heat transfer bellows cools the blood flowing through the artery, to cool the selected organ, distal to the tip of the catheter.

Abstract: A disposable, sterilizable sheath for use on a closed loop Joule-Thomson cryosurgical probe, and the combination of the disposable sheath and the closed loop probe. The sheath is slipped over the probe, thereby separating the probe from the environment. The sheath has a grip which fits over the handle of the cryosurgical probe, and an extendible shroud which can be longitudinally extended to cover tubing and which are attached to the handle. The sheath has a hollow multi-lumen catheter shaped and sized to fit snugly over the cannula of the cryosurgical probe. The catheter is not thermally conductive, preventing transfer of heat from the ambient to the gas mixture, and preventing the freezing of tissues at undesired locations along the catheter. A thermally conductive cap or tip is attached to the distal end of the hollow catheter.

Abstract: A microminiature laminated heat exchanger for use in a cryogenic probe, and a method of manufacture. The heat exchanger has high and low pressure flow patterns etched into oxygen free copper sheets, with the flow patterns being tortuous paths promoting turbulent flow. The sheets containing the flow patterns are bonded into a laminated assembly in the shape of a cylinder, with a high pressure inlet and a low pressure outlet in a first end, and a high pressure outlet and a low pressure inlet in a second end. The high pressure flow path lies alongside the low pressure flow path, with flow in the two paths being in opposite directions, to accomplish counterflow heat exchange. Substantial portions of the flow paths are either parallel to, or transverse to, the longitudinal axis of the heat exchanger, with the resulting heat flow being essentially radial or axial, respectively.

Abstract: A circulatory assist device, having an outer balloon and an inner balloon, with a control space between the outer and inner balloons. The device is mounted on a catheter, collapsed to a sufficiently small diameter to allow insertion into the vascular system of a patient. An expansion mechanism in the device, such as a stent, can be expanded to hold the outer balloon in an expanded state, while control fluid is pumped into and evacuated from the control space to repeatedly collapse and expand the inner balloon. At least one port is formed in the inner balloon, to allow vascular fluid to enter and exit the inner balloon as the inner balloon expands and contracts. After use, the expansion mechanism is contracted to a smaller diameter to allow withdrawal from the vascular system.

Abstract: A circulatory assist device, having a housing and a pumping membrane, with a control chamber and a pumping chamber. The device is mounted on a catheter, collapsed to a sufficiently small diameter to allow insertion into the vascular system of a patient. An expansion mechanism in the device, such as a stent, can be expanded to hold the housing in an expanded substantially rigid state, while control fluid is pumped into and evacuated from the control chamber to repeatedly deflect the pumping membrane. At least one opening is formed in the device, to allow vascular fluid to enter and exit the pumping chamber as the pumping membrane deflects. Introduction and evacuation of control fluid can be synchronized with the heart cycle of the patient. After use, the housing is contracted to a smaller diameter to allow withdrawal from the vascular system.

Abstract: A miniature mixed gas refrigeration system and method of operation are disclosed, having a coaxial catheter with an inner high pressure supply lumen and an outer low pressure return lumen. An optimum gas mixture is formulated from a group of component fluids, according to calculated thermodynamic properties of a group of candidate fluid mixtures. The gas mixture is pressurized by a compressor to a pressure less than 420 psia, for safety reasons. The distal portion of the outer lumen contains a micro-miniature heat exchanger constructed of laminated plates or sheets. The plates or sheets establish high pressure and low pressure passageways, with high surface area, having a tortuous path for the gas flow to maximize heat exchange. The high pressure outlet of the heat exchanger is connected to a Joule-Thomson expansion element where the high pressure gas is expanded isenthalpically to a lower temperature at least as low as 183K.

Abstract: A miniature mixed gas refrigeration system and method of operation are disclosed. An optimum gas mixture is formulated from a group of component fluids, according to calculated thermodynamic properties of a group of candidate fluid mixtures. The gas mixture is pressurized by a compressor to a pressure less than 420 psia, for safety reasons. The compressed gas mixture is passed through a primary heat exchanger, and then through a primary-to-secondary heat exchanger, to precool the gas mixture. The secondary side of the primary/secondary heat exchanger is cooled by a secondary Joule-Thomson refrigeration system. Properly sized flow restrictions in the primary side of the primary/secondary heat exchanger can solidify and trap liquid contaminants that may be in the gas mixture. The gas mixture exiting the primary outlet of the primary/secondary heat exchanger passes to a primary Joule-Thomson expansion element where the high pressure gas is expanded isenthalpically to a lower temperature at least as low as 183K.

Abstract: A closed cycle cryosurgical instrument having a mixed gas assembly that is mounted in a housing and also having a cryosurgical probe unit. By using special (or certain) gas mixtures as opposed to pure gasses, pressure reductions to .perspectiveto. or 1/4 of that required by pure gasses can be obtained. The use of gas mixtures with their attendant lower pressures allows for a closed cycle system since expensive and complex multi-stage compressors are not required. With the gas mixtures it is possible to obtain temperatures in the range of liquid nitrogen using a Joule-Thomson based system.