Abstract: An electrosurgical probe (10) comprises a shaft (13) having an electrode array (12) at its distal end and a connector (19) at its proximal end for coupling the electrode array to a high frequency power supply (28). The shaft includes a return electrode (55, 56) recessed from its distal end and enclosed within an insulating jacket (18). The return electrode defines an inner passage (83) electrically connected to both the return electrode and the electrode array for passage of an electrically conducting liquid (50). By applying high frequency voltage to the electrode array and the return electrode, the electrically conducting liquid generates a current flow path between the target site and the return electrode so that target tissue may be cut or ablated. The probe is particularly useful in dry environments, such as the mouth or abdominal cavity, because the electrically conducting liquid provides the necessary return current path between the return electrode and the target site.

Abstract: An adaptor cable and methods are provided for use with electrosurgical bipolar instruments and standard commercially available electrosurgical generators that reduce arcing. The adaptor cable limits the peak-to-peak voltage developed between the electrodes of the electrosurgical instrument by providing a minimum load impedance between the output terminals of the electrosurgical generator.

Abstract: Dual program audio apparatus is provided having two or more sources of input audio program signals, switching circuitry for selecting two of the input audio signals for amplification, one or more amplifiers for amplifying the selected input audio program signals, and one or more audio speakers for enabling a listener to hear both audio programs simultaneously. Volume control circuitry is provided for selecting a higher volume level for a foreground program and a relatively lower volume for a background program and circuitry is provided for selectively interchanging the foreground and background programs either instantaneously or gradually and continuously.

Abstract: A method for transmyocardial revascularization of the heart of a patient comprises introducing a probe (10) into the thoracic cavity through a percutaneous penetration, a thoracotomy or a sternotomy. An active electrode surface (58) is then positioned adjacent a wall of the patient's heart, e.g., the ventricular wall. Electrically conducting liquid (50) is directed to the heart wall to provide a current flow path and high frequency voltage is applied to ablate or disintegrate tissue at the heart wall. The probe is then axially translated towards the ventricular wall to form a revascularizing channel or artificial vessel from the ventricle to the myocardium to increase blood flow therethrough.

Abstract: An electrosurgical probe comprises a shaft having an electrode array disposed over a recessed surface at its distal end. The electrode array includes a plurality of isolated electrode terminals, and an electrosurgical power supply may be connected to the array via a connector at the distal end of the probe. The electrosurgical power supply will be provided with a plurality of independently limited or controlled current sources. By applying very high frequency electrical energy to the electric array with the power supply, target issue may be ablated while heat dissipation through low impedance past is minimized. The probe is particularly suitable for treatment of surfaces of body lumens, such as the mucosal surface within an enlarged prostate.

Abstract: Adaptors are provided for use with electrosurgical bipolar instruments and standard commercially available electrosurgical generators that reduce coagulum buildup and sticking on electrosurgical instruments. A first type of adaptor converts a high voltage, high crest factor output voltage waveform typical of conventional electrosurgical generators to a more desirable lower voltage, lower crest factor regime. A second type of adaptor limits the peak open-circuit voltage supplied by a conventional electrosurgical generator to an electrosurgical instrument.

Abstract: Apparatus and methods are provided for performing an in situ characterization of a tissue mass which may be normal, malignant, or benign, and, based on the measured characteristics of the tissue mass, therapeutically treating the tissue mass to cause necrosis of the tissue. In an illustrative preferred embodiment, the characterization of the tissue is accomplished by measuring an electrical property of the tissue, such as electrical impedance, while treatment is accomplished by supplying heat to the tissue to induce cauterization.

Abstract: A surgical instrument having a resistively-heated heating component responsive to a power source for generating thermal excitation effective for cutting tissue and carrying out hemostasis. The surgical instrument includes a support assembly having two leg extensions connected in heat transfer relationship with the heating component. Two thermal transition regions are provided within the heating component and have extents effective to provide a decreasing temperature gradient and to restrict temperature levels exhibited at the support assembly. The support assembly is formed of high thermally conductive material and extends from the transition regions to an elongate shaft. This shaft is in heat transfer relationship with the support assembly and is formed from a high thermally conductive material.

Abstract: An instrument for use in endoscopic surgery is provided. The instrument has a heating element with a working surface for providing hemostasis at an auto-regulated temperature. The working surface may include a tapered edge for providing thermally-enhanced cutting and a non-stick coating for operating the instrument at low auto-regulation temperatures. A process for making the instrument is also provided. Additionally, a method of performing endoscopic surgery on a patient's internal tissue is also provided.

Abstract: An irrigation arrangement is provided for electrically powered endoscopic probes that supplies the surgeon with suction or irrigation on demand. The irrigation arrangement is described for use with endoscopic probes employing thermal auto-regulating and bipolar electrosurgical probe tip configurations. An extendable shroud is also provided for selectively covering tip of the endoscopic probe while positioning or manipulating the endoscopic probe at the surgical site.

Abstract: Bipolar surgical instruments for simultaneously cutting and coagulating tissue are provided that feature increased manufacturability and durability, reduced component cost and reduced assembly requirements. The bipolar instruments include opposite polarity electrodes isolated by a layer of electrical insulation deposited and specially prepared to reduce electrical breakdown and increase smoothness. A pivot pin connecting the electrodes is impregnated with hydrophobic material, and organic materials are generally avoided in the components and manufacture of the instruments. A simplified design for an endoscopic bipolar instrument is also provided to reduce cost and improve manufacturability and durability of such devices.

Abstract: An instrument for use in endoscopic surgery is provided. The instrument has a reusable shaft to which a disposable working tip can be removably attached. The disposable working tip has a working surface for providing hemostasis at an auto-regulated temperature. The working surface may include a tapered edge for providing thermally-enhanced cutting and a non-stick coating for operating the instrument at low auto-regulation temperatures. The instrument is capable of being used for a wide variety of endoscopic surgical procedures.

Abstract: An instrument for use in surgery is provided. The instrument has a heating element with a working surface for providing hemostasis at an auto-regulated temperature. The working surface may include a tapered edge for providing thermally-enhanced cutting and a non-stick coating for operating the instrument at low auto-regulation temperatures. A process for making the instrument is also provided. Additionally, a method of performing surgery on a patient's tissue is also provided.

Abstract: Methods and apparatus are provided for use in performing electrosurgery, wherein a power supply supplies an electrosurgical instrument with a low voltage power signal having a substantially constant peak-to-peak voltage that is independent of the load impedance and which has a crest factor near unity. A power supply is provided to supply a voltage waveform in accordance with the methods of the invention. A clipping circuit is also provided to permit practice of the methods using conventional electrosurgcial generators and previously known electrosurgical instruments, wherein the voltage amplitude and waveform is modified to the desired regime.

Abstract: A catheter system is provided that includes an electrode array near the distal end of the catheter. High frequency current is supplied between the electrodes of the array and a common electrode to cause heating of material lying between the electrodes. The catheter may include means for steering it through the lumen. In a preferred embodiment, the steering means includes a plurality of steering wires in contact with the catheter body. The steering wires may be formed of a shape-memory alloy. Wires of such an alloy may be made to contract when heated above a preselected transition temperature. The wires may be heated by the selective conduction of electrical current through them. Conduction of current through the steering wires is controlled based on the current flowing through the electrodes of the array. An inflatable balloon may be included proximal to the electrode array for dilating the vessel after the occlusion has been penetrated by the electrode array.

Abstract: A non-volatile memory disposed within electrically powered medical equipment is described. The non-volatile memory may be preprogrammed to store utilization limits and parametric data for the equipment. An external control module may be programmed to store the utilization history for the equipment in the non-volatile memory on an on-going basis. The control module compares the utilization limits and utilization history during each use, and disables the equipment if a utilization limit is exceeded. The control module may also use the parametric data stored in the non-volatile memory to regulate the power supplied to the equipment.

Abstract: System and apparatus for producing neutron beams having an energy spectrum and intensity suitable for use in neutron capture therapy. The apparatus employs a rotating carriage which supports an annular target support region carrying a target material such as lithium metal. The carriage rotatably positions the target material before the pathway of charged particles generated from an accelerator course of ions. To cool the assemblage, the carriage is formed having an internally disposed chamber within which a coolant is directed from an external source. Because of the centrifugal forces imposed upon this internally-disposed coolant, it is forced to a heat exchange position adjacent the target region. The assemblage of carriage and accelerator are retained within a containment chamber under vacuum.

Abstract: Endoscopic surgical instruments are provided that have detachable working ends for use with a reusable handle portion. The detachable working end includes bipolar electrodes on opposing movable members for passing a high frequency current through tissue for simultaneously severing or manipulating the tissue and causing hemostasis of the tissue. An electrically insulating material is interposed between the movable members so that the electrodes are spaced apart from 0.002 to 0.050 inches and the current passes between the opposing electrodes through the tissue.

Abstract: A catheter comprises a catheter body having a proximal end, a distal end, and an electrode array disposed near the distal end. The electrode array includes a plurality of isolated electrode terminals. The electrode array and a common electrode are connected to a high frequency power supply, and the common electrode may be located on the catheter, may be secured separately to a patient's skin, or may be formed as part of a movable guidewire. By contacting the electrode array against a target location in the patient's body, the target location may be selectively heated, with current density being contacted at the points of contact between the electrode terminals and the tissue or stenotic material. For example, by positioning the common electrode within a stenotic region and contacting a leading surface of the stenotic region with the electrode array, the stenotic material can be heated by applying a high frequency voltage between the electrode array and the common electrode.

Abstract: Endoscopic surgical instruments are provided that have bipolar electrodes on opposing movable members for passing a high frequency current through tissue for simulataneously severing or manipulating the tissue and causing hemostasis of the tissue. An electrically insulating material is interposed between the movable members so that the electrodes are spaced apart from 0.002 to 0.050 inches and the current passes between the opposing electrodes through the tissue. Methods of endoscopically achieving hemostasis while simultaneously, manipulating and cutting tissue are also provided. Use of a constant voltage high frequency power supply to deliver current to the tissue to cause hemostasis is described in conjunction with those methods.