Abstract: A flexible cryosurgical catheter having a deflectable segment adjacent its distal end, a pull wire through said catheter connected to the deflectable segment, and a deflection mechanism in its handle for pulling on the pull wire to establish a desired curvature in the deflectable segment.

Abstract: In an oil-lubricated helium compressor unit, the adsorber can retain all of the oil that might be transferred from the compressor to the adsorber before the system shuts down. No oil is ever transferred or transferable to, for example, the expander in a GM type refrigeration system connected to the unit. The compressor itself will shut down because of a protective switch or seize for lack of oil before any oil carries outside the compressor unit. The unit and the connected refrigeration system can run for more than a selected design life before the compressor shuts down because the limit of oil in the adsorber has been reached. The adsorber can retain as much oil as might leave the compressor over the life of the system plus a safety margin of at least 25%. The adsorber need not be serviced or replaced for the life of the system.

Abstract: A method and apparatus for inflating a balloon at a distal portion of an elongated delivery catheter to contact surrounding biological tissue, and expanding a refrigerant adjacent the balloon to cool the biological tissue to render it non-viable. The inflation of the balloon can be accomplished with the expanded refrigerant or with a separate pressurized fluid. The balloon can act as a heat transfer element, or there can be a separate heat transfer element on the catheter adjacent the balloon. The apparatus can be used to perform a dilation procedure, such as angioplasty, in conjunction with cooling of the surrounding tissue.

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: In an oil-lubricated helium compressor unit, the adsorber can retain all of the oil that might be transferred from the compressor to the adsorber before the system shuts down. No oil is ever transferred or transferable to, for example, the expander in a GM type refrigeration system connected to the unit. The compressor itself will shut down because of a protective switch or seize for lack of oil before any oil carries outside the compressor unit. The unit and the connected refrigeration system can run for more than a selected design life before the compressor shuts down because the limit of oil in the adsorber has been reached. The adsorber can retain as much oil as might leave the compressor over the life of the system plus a safety margin of at least 25%. The adsorber need not be serviced or replaced for the life of the system.

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 sealing assembly for attaching pliable tubes to rigid connecting members, for high pressure, low temperature service, which seals by compressing a sealing wafer around the pliable tubes. The pliable tubes pass through holes in the sealing wafer. As the wafer seal is axially compressed, the wafer seal is restrained against radial expansion, thereby exerting an inward radial pressure on the holes through the wafer seal to cause an hermetic seal between the wafer seal and the pliable tubes. A swage bushing can be used, with swage tubes that are swaged onto the pliable tubes by a swage clamp, for the purpose of axially restraining the pliable tubes.

Abstract: An apparatus and method for automatic operation of a refrigeration system to provide refrigeration power to a catheter for tissue ablation or mapping. The primary refrigeration system can be open loop or closed loop, and a precool loop will typically be closed loop. Equipment and procedures are disclosed for bringing the system to the desired operational state, for controlling the operation by controlling refrigerant flow rate, for performing safety checks, and for achieving safe shutdown.

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: An extended stem globe valve for use with cryogenic fluids, wherein the elongated shaft between the valve seal or disk and the actuator is constructed so that rotational movement of the actuator results in linear movement of the shaft, without imparting a large rotational movement of the shaft about its longitudinal axis and with reduced thermal conduction between the mating parts. Coupling of the valve disk to a valve disk retainer is effected in the area above the valve seat. The valve also includes a shaft insulator so constructed and arranged to retain leakage fluid in a volume space closer to the valve seat. Optionally the valve can include bellows sealing of the shaft to prevent fluid from contacting the uppermost portion of the shaft.

Abstract: A sheath for use on a closed loop Joule-Thomson cryosurgical probe, and the combination of the 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. The thermally conductive cap or tip is biased against the cold tip on the probe by a biasing element in the sheath assembly, to promote heat transfer.

Abstract: A two-stage pulse tube refrigerator comprises a pressure wave generator-compressor, first stage and second stage regenerators, first stage and second stage pulse tubes, heat exchangers and a hybrid phase shift mechanism for the first and second stage pulse tubes. The second stage phase shift mechanism includes double fixed orifices while the first stage shifter is an arrangement including one of a) 4 valves, b) 5 valves c) 2 active buffers or d) 3 active buffers. The double fixed orifice phase shifter is located either at room temperature or is thermally connected with the first stage cold end. Two-stage pulse tube refrigerators with a hybrid phase shifter have increased second stage regenerator performance at lower temperature. Pressure drop through the valves and compressor power consumption are decreased, and losses from phase interaction between each stage are eliminated.

Abstract: The present invention provides a cryogenic device and system for treating biological tissue, which includes at least two media-flow lumens and a media-expansion element for cooling media flowing within the device. A cooling portion of the device is located along a portion of one of the media-flow lumens. The cooling portion is of a construction suitable for good contact with tissue selected for treatment. Preferably, the device and system employ one or more closed media-flow pathways for efficient recycling of the media employed. Preferably, the device and system also employ efficacious heat-exchange relationships between media-flow conduits for optimal cooling. The device and system are particularly designed for the formation of lesions in biological tissue, most particularly, the formation of deep, elongated and continuous lesions in cardiopulmonary tissue. The present invention also provides a method of using the cryogenic device and system in the treatment of biological tissue.

Abstract: A method and apparatus for using a secondary refrigerant to precool and liquefy a primary refrigerant, then vaporizing and expanding the primary refrigerant to cool a cold tip of a cryosurgical instrument for ablation of biological tissue, such as cardiovascular tissue, in particular endocardiac tissue and tissue inside a cardiac blood vessel. The secondary refrigerant has a critical temperature above the critical temperature of the primary refrigerant, and a cooling temperature below the critical temperature of the primary refrigerant, thereby facilitating the use of the precooling step to provide liquid primary refrigerant in an operating room environment in which the primary refrigerant could not otherwise be provided in the liquid phase.

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: An optimum gas mixture formulated from a group of component fluids, for use in a miniature mixed gas refrigeration system. The gas mixture has appropriate components, in appropriate concentrations, to optimize refrigeration power and heat transfer capacity, and to minimize plugging of the Joule-Thomson expansion element. The gas mixture is pressurized by a compressor to a pressure less than 750 psia, and preferably less than 420 psia, for safety reasons, and supplied to a heat exchanger. 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. This low temperature gas cools a heat transfer element mounted in the distal end of the probe, to cool an external object. Return gas flows back through the heat exchanger to pre-cool the incoming high pressure gas mixture.

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 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.