A cryosurgical probe has a refrigerant supply conduit for conducting refrigerant to the hollow thermally-conductive probe tip. A refrigerant exhaust conduit extends through the probe into the tip and the end of the exhaust conduit in the tip is positioned a selected distance proximally of the end of the supply conduit. Thus, when refrigerant flows through the supply conduit to the tip, it tends to follow a flow path taking it more or less directly to the exhaust conduit. This creates a dead gas space inside the tip proximally of the end of the exhaust conduit, thereby minimizing direct cooling of portions of the probe adjacent to and proximally of the dead gas space and confining the freeze zone distal to that space. By adjusting the height of the exhaust conduit end proximally of the supply conduit end, the size of the freeze zone at the tip can be controlled. Further, if the probe has a defrost mode, defrost is enhanced because only the working end of the tip need be warmed.
A cryosurgical instrument having a tip which is cooled by the Joule-Thomson expansion of a pressurized gas. The gas is conveyed to the tip by an inlet tube and exhausts through an exhaust tube connected to the rear of a fitting. The tip is connected to the forward portion of the fitting. The rear and forward portions of the fitting are rotatably connected by a bearing coupling which enables the tip to be rotated independent of the inlet and exhaust tubes.
A cryosurgical probe having a probe head which is cooled by Joule-Thomson cooling, and is then used to freeze bodily tissue during a surgical procedure. A steerable catheter is connected between the probe head and a probe handle to enable the probe head to be guided with safety and precision along arteries of the body to the target area.
Cryosurgical apparatus includes an elongate cryoprobe having a cooling portion and an electrically conductive first portion in the region of the cooling portion. A removable sheath having an electrically conductive second portion is received on the cryoprobe with its electrically conductive second portion spaced from the electrically conductive first portion of the cryoprobe. Electrical insulation is interposed between the first portion and the second portion. Coolant material supplied to the cryoprobe produces tissue freezing in the region of the cooling portion. Electromagnetic energy supplied to either the first portion or the second portion, while the other of such first portion or second portion is connected to ground, provides selective heating in tissue surrounding an iceball produced by the cooling portion to control the configuration of the iceball.
A cryogenic device utilizing pressurized coolant gas and provided with a single control easily manipulatable by finger pressure to selectively furnish either continuous freezing or continuous thawing, each alone or in sequence. The expansion chamber is pressurized only when the control lever is deliberately held depressed and, in consequence, either the expansion chamber or the coolant inlet subassembly can be detached or exchanged without risk to the operator or the equipment and without need for closing off the coolant supply. A pressure regulator forming a part of the device limits the maximum possible pressure in the expansion chamber and exhaust passages to a safe value. The device is substantially noiseless in operation and the control is operable through first and second stages by movement in the same direction to provide freezing or warming modes at the user's option and is self-locking in the freezing mode but is automatically disengaged therefrom upon movement into the thawing mode.
Electronic circuitry 22, 24, 26 is thermally checked by cooling with liquified nitrogen from a cryogenic delivery unit 19, directly by means of a stream 10 or a spray 28 delivered through an aperture 11, 30 of the delivery unit 19 spaced from the surface of the circuitry.
