Abstract: A small diameter steerable guidewire that is used to guide a catheter in transluminal coronary angioplasty is provided with a pair of electrodes for measuring the cross-sectional area of a blood vessel and for measuring blood flow. The guidewire includes a shaft and a tip attached to the distal end of the shaft. The shaft is torsionally rigid along its length and includes a conductive main tube and a wire extending through the main tube. The tip, which can be bent to a prescribed curve when relaxed, is sufficiently flexible to adapt to and follow the contours of a blood vessel. The tip includes a tapered extension of the wire in the shaft. A proximal electrode and a distal electrode are coaxially mounted on the tapered wire and are electrically connected to the main tube and the wire, respectively. The electrodes are axially spaced apart by a predetermined distance. The distal electrode is preferably a conductive, helically-wound spring.

Abstract: An electrosurgical unit for conducting a predetermined ionizable gas in a jet stream to the tissue at a predetermined flow rate sufficient to clear natural fluids from the tissue and to substantially expose the tissue stroma and for exposing the gas to an electrical radio frequency energy to ionize the gas in conductive pathways in the gas jet stream. The unit includes a nozzle which is releasably connected to a handle for easy manipulation by a surgeon with the nozzle including means for supporting an electrode in an optimal position for initiation of the ionization of the gas. Also, a connecting system is disclosed for connecting the hose on which the handle is mounted to a gas delivery apparatus and supply or electrical energy which permits the hose to rotate while maintaining a positive hermetic seal to prevent the hose from kinking during use by a surgeon.

Abstract: An electrosurgical generator in an electrosurgical unit (ESU) controls the repetition rate and the energy content of bursts of RF energy delivered to a gas jet supplied by the ESU, in order to maintain RF leakage current within acceptable limits while still achieving a sufficient state of ionization in the gas jet to reliably initiate the conduction of arcs to the tissue. The repetition rate of the RF bursts is substantially reduced in an inactive state when no arcs are delivered. A relatively small number of the RF bursts delivered during the inactive state have an increased or boosted energy content to assure an adequate ionization state in the gas jet.

Abstract: An electrosurgical technique of achieving coagulation involves conducting a predetermined ionizable gas in a jet to the tissue at a predetermined flow rate sufficient to clear natural fluids from the tissue and to substantially expose the tissue stroma. Electrical radio frequency energy is conducted to the tissue in ionized conductive pathways in the gas jet. To achieve fulguration, the electrical energy is conducted as arcs in the ionized conductive pathways. To achieve a non-contact type of electrosurgical desiccation, the electrical energy is conducted as a non-arcing diffuse current in the ionized conductive pathways.

Abstract: An electrosurgical generator in an electrosurgical unit (ESU) controls the repetition rate and the energy content of bursts of RF energy delivered to a gas jet supplied by the ESU, in order to maintain RF leakage current within acceptable limits while still achieving a sufficient state of ionization in the gas jet to reliably initiate the conduction of arcs to the tissue. The repetition rate of the RF bursts is substantially reduced in an inactive state when no arcs are delivered. A relatively small number of the RF bursts delivered during the inactive state have an increased or boosted energy content to assure an adequate ionization state in the gas jet.

Abstract: An electrosugrical unit for conducting a predetermined ionizable gas in a jet stream to the tissue at a predetermined flow rate sufficient to clear natural fluids from the tissue and to substantially expose the tissue stroma and for exposing the gas to an electrical radio frequency energy to ionize the gas in conductive pathways in the gas jet stream. The unit includes a nozzle which is releasably connected to a handle for easy manipulation by a surgeon with the nozzle including means for supporting an electrode in an optimal position for initiation of the ionization of the gas. Also, a connecting system is disclosed for connecting the hose on which the handle is mounted to a gas delivery apparatus and supply or electrical energy which permits the hose to rotate while maintaining a positive hermetic seal to prevent the hose from kinking during use by a surgeon.