Abstract: An electrosurgical ablation probe is provided having a shaft with a proximal end portion and a tongue-shaped distal end portion sized to fit within confined (e.g., narrow) spaces within the patient's body, such as the spaces around the articular cartilage between the femur and tibia and the spaces between adjacent vertebrae in the patient's spine. The probe includes at least one active electrode integral with or coupled to the tongue-shaped distal end portion and a connector on the proximal end portion for coupling the active electrode to an electrosurgical generator. The tongue-shaped distal end portion is substantially planar, and it offers a low profile, to allow access to confined spaces without risking iatrogenic injury to surrounding tissue, such as articular cartilage.

Abstract: A method is provided for applying electrical energy to a tissue structure within a patient's body. The method includes positioning an electrosurgical probe adjacent to the tissue structure so that an electrode array including a plurality of isolated electrode terminals is brought into at least partial contact with the body structure. A high frequency voltage is then applied between each electrode terminal within the electrode array and a common, return electrode. Current flow from the electrode terminals is selectively limited to minimize low electrical impedance paths emanating from the electrode array. The present invention takes advantage of the differences in electrical properties between a target tissue and the surrounding conductive liquid (e.g. isotonic saline irrigant) in the region immediately adjacent to the electrode array to ablate the target tissue while minimizing overheating of the surrounding liquid.

Abstract: Surgical forceps which are configured having oppositely disposed tissue grasping surfaces at the tip regions of corresponding tines. An electrically insulative spacer assembly is positioned on and supported from at least one of the tissue grasping surfaces to space the tissue contacting surfaces apart an optimized distance, T, when the tines are in a substantially closed orientation. A preferred, strip form of spacer assembly formed of an electrically insulative material is employed and improved current paths are defined between the grasping surfaces to derive an efficient and effective hemostasis substantially without sticking of tissue to the surfaces. The geometric configuration of the spacer regions functions to enhance cleanability of the forceps and the tines of the forceps additionally are formed with side and nose surfaces at the tip regions having effective side surface current delivery areas improving forceps performance when used in a coagulative painting modality.

Abstract: An electrosurgical system comprises an electrosurgical probe and an electrosurgical power supply for ablation and resection of soft tissue in the presence of electrically conductive fluids, such as isotonic saline. In one embodiment, the probe includes a shaft having an electrode array with a plurality of electrically isolated electrode terminals and a return electrode spaced proximally from the electrode array. The power supply includes a plurality of current limiting elements for limiting current based on impedance between the electrode terminals and the return electrode. By applying high frequency voltage to the electrode array, target tissue may be cut or ablated while heat dissipation through low impedance paths, such as saline, is minimized. The power supply has an operating frequency less than 400 kHz, usually about 100 kHz, for limiting current penetration into the tissue.

Abstract: A method for transmyocardial revascularization of the heart of a patient includes positioning an active electrode surface in close proximity to a target site on the wall of a patient's heart, and applying high frequency voltage between the active voltage surface and a return electrode to ablate tissue at the heart wall. The high frequency voltage ablates, i.e. volumetrically removes the heart tissue, and the electrode surface is axially translated into the space vacated by the removed tissue to bore a channel through the heart tissue. The active electrode surface may be introduced into the thoracic cavity and placed adjacent the epicardium to form an inward channel toward the ventricular cavity, or it may be delivered into the ventricular cavity of the heart and positioned adjacent the endocardium to form a channel extending outward towards the epicardium.

Abstract: An electrosurgical probe (10) comprises a shaft (13) having an electrode array (58) 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 (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 return electrode and the electrode array 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 active and return electrodes.

Abstract: A method for transmyocardial revascularization of the heart of a patient includes positioning an active electrode surface in close proximity to a target site on the wall of a patient's heart, and applying high frequency voltage between the active voltage surface and a return electrode to ablate tissue at the heart wall. The high frequency voltage ablates, i.e. volumetrically removes the heart tissue, and the electrode surface is axially translated into the space vacated by the removed tissue to bore a channel through the heart tissue. The active electrode surface may be introduced into the thoracic cavity and placed adjacent the epicardium to form an inward channel toward the ventricular cavity, or it may be delivered into the ventricular cavity of the heart and positioned adjacent the endocardium to form a channel extending outward towards the epicardium.

Abstract: An electrosurgical system and method allow the surgical team to perform electrosurgical interventions, such as ablation and cutting of body structures, while limiting the depth of necrosis and limiting damage to tissue adjacent the treatment site. The system includes an electrosurgical probe having a shaft with a proximal end, a distal end, and at least one active electrode at or near the distal end. The active electrode includes at least one active portion having a surface geometry configured to promote substantially high electric field intensities and associated current densities between the active portion and the target site when a high frequency voltage is applied to the electrodes. These high electric field intensities and current densities are sufficient to break down the tissue by processes including molecular dissociation or disintegration.

Abstract: A surgical instrument is described that incorporates bipolar electrodes on opposing shearing members for passing a high frequency current through the tissue for causing hemostasis of the tissue and for cutting the tissue. An electrically insulating material is interposed between the shearing 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 and not between the opposing shearing surfaces. The insulating material has a higher hardness than the opposing members to reduce wear of the insulation and provide a self-sharpening feature. Methods of simultaneously causing tissue and severing tissue are also provided. The 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.

Abstract: An electrosurgical resecting instrument is provided having a resecting loop electrode on the distal end of a shaft and coupled to a high frequency voltage source. The loop electrode is configured to fit within a working end of a resectoscope (discussed below) and to remove small portions of tissue (e.g., chips of tissue). The loop electrode includes an active portion with a surface geometry configured to promote substantially high electric field intensities and associated current densities between the active portion and the target site when a high frequency voltage is applied to the electrode. The edges of the electrode are oriented substantially parallel to the shaft so that they will face the tissue as the electrode is moved axially in the cutting direction. This orientation facilitates formation of the vapor layer between the electrode edges and the tissue.

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: Method, system, and apparatus for evaluating hemodynamic parameters and, in particular, cardiac output. A pulmonary artery catheter is described which incorporates a diffuser of gas biocompatible with the body such as oxygen at an indwelling region such that the gas may be employed to carry out a dilution technique to measure cardiac output. A mixed venous blood gas level then is measured at the pulmonary artery using a gas sensor. The preferred gas sensor employs oximetry to derive values of mixed venous oxygen saturation. An alternate embodiment utilizes an electrode/electrolyte approach as the gas sensor to carry out measurement of dissolved oxygen in mixed venous blood. The system utilizes a microprocessor driven controller to develop multiple evaluations over sequential measurement intervals and to compute a variety of hemodynamic parameters including the noted cardiac output.

Abstract: A surgical instrument is described that incorporates bipolar electrodes on opposing shearing members for passing a high frequency current through the tissue for causing hemostasis of the tissue and for cutting the tissue. An electrically insulating material is interposed between the shearing 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 and not between the opposing shearing surfaces. The insulating material has a higher hardness than the opposing members to reduce wear of the insulation and provide a self-sharpening feature. Methods of simultaneously causing tissue and severing tissue are also provided. The 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.

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.

Abstract: An electrosurgical system for applying electrical energy to a tissue structure within a patient's body comprises an electrosurgical probe and one or more high frequency power supplies. The probe comprises a shaft having an electrode array of isolated electrode terminals at its distal end. The terminals are each coupled to one of a multiplicity of current limiting elements, such as inductors. The inductors, together with the inherent capacitance of the load, form a series resonant output circuit having a resonant frequency greater than the operating frequency of the power supply.

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.

Abstract: A monopolar electrosurgical instrument for utilization with endoscopic and laparoscopic surgical procedures. The instrument is structured so as to substantially eliminate the adverse effects occasioned by capacitive coupling between the instrument and tissue adjacent thereto within the body being operated upon. Capacitive coupling is controlled through the implementation of the shaft structure itself with an electrically insulative polymeric material of low dielectric constant which is combined with a current conductor centrally disposed therein which is of minimum diameter effective to carry requisite current to a working tip. A shield arrangement may be provided such as a coextruded electrically conductive wire mesh surmounting the internally disposed electrical conductor. This shield, in one embodiment may be coupled with return ground employing electrical connectors which assure proper coupling with source and ground.

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 electrosurgical probe comprises a shaft having an electrode array at its distal end and a connector at its proximal end. The array includes a plurality of isolated electrode terminals, and an electrosurgical power supply is provided with a multiplicity of independently limited or controlled current sources and a connector. The electrosurgical probe and the power supply may be connected through their respective connectors so that the independent current sources are connected to individual electrode terminals. In other configurations, the probe includes a single electrode terminal spaced from a return electrode such that when the electrode terminal is brought adjacent a tissue structure immersed in electrically conductive fluid, the electrically conductive fluid completes a conduction path between the electrode terminal and the return electrode.

Abstract: An electrosurgical probe (10) comprises a shaft (13) having an electrode array (58) 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 (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 return electrode and the electrode array 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 active and return electrodes.