Abstract: A device for biological tissue stimulation continually undertakes an evaluation of the stimulation sensitivity of the biological tissue to be stimulated, so that the stimulation energy can be set at a level just high enough to evoke a tissue response. Each evaluation ensues by stimulating the tissue with progressively lower energy levels, until no tissue response is detected. In order to improve matching of the stimulation energy to the varying stimulation sensitivity, and to keep the number of unsuccessful stimulation attempts, which occur during each evaluation, low, a device is disclosed wherein calculation of the stimulation sensitivity occurs at periodic time intervals, each time interval having a duration which is selected dependent on the variation in the stimulation sensitivity between the two most recently occurring calculations of the stimulation sensitivity. The device may be, for example, a heart pacemaker. A method for tissue stimulation is also disclosed.

Abstract: An ultrasound type treatment apparatus includes an inner sheath covering an ultrasonic transmission member having a first suction passage and defining a space relative to the ultrasound transmission member and an outer sheath covering the inner sheath and defining a space relative to the inner sheath. In the treatment apparatus, a liquid medium supply passage is provided at one of the space between the ultrasound transmission member and the inner sheath and space between the inner sheet and the outer sheet to supply a liquid medium to the distal end of the ultrasound transmission member. A second suction passage is formed at the other of the space between the ultrasound transmission means and the inner sheath and space between the inner sheath and the outer sheath. The first suction passage is connected by a suction tube to the second suction passage.

Abstract: A method and apparatus for performing stereotactic surgery upon a target within a skull establishes a first, predetermined geometric relationship between a skull mount fixture mounted on the skull and a scanning table surface upon which the skull is supported; and that geometric relationship is duplicated by a displacement bar mounted upon the skull mount fixture.

Abstract: An implantable cardioverter having circuitry for generating high energy cardioversion and defibrillation pulses. The output circuitry is so configured that it may provide simultaneous pulse, multiple electrode; sequential pulse, multiple electrode; or single pulse, two electrode defibrillation and/or cardioversion pulse regimens. The output circuitry is configured to allow delivery of energy sequentially from two capacitor banks during sequential pulse regimens and to deliver the energy stored in both capacitor banks simultaneously during simultaneous pulse, multiple electrode and single pulse, two electrode defibrillation pulse regimens.

Abstract: A catheter type laser illuminating apparatus for thermally removing an atheroma generated in a blood vessel. The illuminating apparatus comprises a catheter arranged to be inserted into a blood vessel, the catheter being equipped with an ultrasonic transducer for transmitting and receiving an ultrasonic wave to generate an electric signal corresponding to the reception ultrasonic wave. The catheter is further equipped with a laser transmission fiber for emitting the laser light. Also included in the illumination apparatus is a M-mode image producing section for producing an image representative of the dimension of the atheroma on the basis of the electric signal from the ultrasonic transducer. The image is displayed on a CRT in a corresponding relation to an illumination condition of the laser light to the atheroma which is at least one of an illumination time and an illumination power.

Abstract: An implantable cardiac deibrillator is provided having a battery, capacitive means, means coupled to the battery for charging the capacitive means, and means for coupling the capacitive means to a patient's heart, for delivering a high voltage shock to the heart. Current leakage from the capacitive means is detected. If the current leakage exceeds a predetermined amount, charging of the capacitive means is terminated. In one embodiment, voltage at the patient is directly sensed. In another embodiment, the voltage across a resistance located in series with the patient is sensed. In another embodiment, a test charge is provided for a short interval. The capacitive means is sensed to determine excessive loss of energy after the test charge. If excessive loss of energy is determined, charging is terminated.

Abstract: A method for analyzing muscle function including the steps of: (a) locating in a human control subject a predetermined muscle group activatable to produce a given torque; (b) fixing over each of a plurality of individual muscles in the group an electrode adapted to detect myoelectric signals generated therein; (c) activating of the muscles to generate myoelectric signals therein; (d) processing the myoelectric signals to determine a plurality of predetermined values thereof; (e) repeating steps (a), (b), (c) and (d) for each of a plurality of other control subjects; (f) determining a normative range of the predetermined values determined in steps (d) and (e); (g) repeating steps (a), (b), (c) and (d) for a human test subject; and (h) comparing the predetermined values determined in step (g) with the normative range determined in step (f). Dysfunction in the muscle group of the test subject can be determined by comparison of the processed myoelectric signal values.

Abstract: The present invention provides a method, and apparatus for accomplishing same, for defibrillating a mammal in need of defibrillation employing multiple bursts of electrical current delivered to the mammal, the timing between said bursts being based upon the mammal's fibrillation cycle length.

Abstract: An ultrasonic probe has an elongated form with an end. A transducer element array is disposed in the probe for emitting ultrasonic wave frontward with respect to the end of the probe and receiving echo ultrasonic waves. The transducer element array converts the received echo ultrasonic waves into corresponding electric echo signals. The electric echo signals are processed according to a predetermined aperture synthesis technique, and thereby an image signal is generated on the basis of the electric echo signals. An image of a region in front of the end of the probe is reproduced in response to the image signal.

Abstract: A system (10) is disclosed that includes a monitor (16) for use in performing 12-lead electrocardiographic (ECG) and body surface mapping (BSM) analyses on a patient (12) with a single ten-electrode cable set (14). The monitor receives nine leads of data from the electrode cable set and initially preprocesses it to simplify further analysis. Then the data is transformed to produce a spatial distribution relative to the patient's chest, representative of the data that would be collectible with a 192-electrode set. Feature extraction techniques are also described for use in evaluating transformed, as well as conventional, BSM data with respect to clinically evaluated populations. In that regard, features of interest are extracted from the data and statistically analyzed to detect select cardiac conditions.

Abstract: A method and apparatus for measuring oxidative metabolism in an internal organ or tissue of interest wherein a percutaneous intravascular approach is utilized to bring a light-transmitting and receiving scope into contact with the site to be assessed. The tip of the scope is adapted so that the light-transmitting optical fiber(s) and light-receiving optical fiber(s) are in divergent relationship so as to increase the photon pathlength through the tissue of interest to provide optical information from a substantial volume of tissue relative thereto.

Abstract: An ultrasonic imaging system employs a processing circuit which enables the imaging system to accurately display the location of an element in a body by utilizing a transducer which provides an electric signal when an ultrasonic wave impinges thereon. The electric signal is processed to determine the maximum amplitude signals during an entire frame of the ultrasonic imaging system. The signals are characterized in terms of the line at which the signal appears or the ray at which the signal appears and the pixel or location along that line. This information regarding ray and pixel serves as X-Y coordinates enabling one to accurately locate the element and transducer on the displayed image by intensifying the display at that location or by adding color or by producing some other visual effect such as blinking, and so on. Thus the disclosed apparatus in its various forms provides ultrasonic position indication without adjustment whereby one shows the exact location of the localizing transducer.

Abstract: A rate-responsive dual-chamber antitachycardia pacer and pacing method which automatically diagnoses and supports a patient's hemodynamic status by measuring metabolic demand and sensing intracardiac electrograms to determine whether the heart is beating normally or under conditions of bradycardia, tachycardia, or fibrillation. The pacer supports the patient's metabolic demand by electrically stimulating the heart at a pacing rate driven either by the heart's sinus node or, alternatively, by the patient's metabolic demand (a metabolic demand indicator), as determined by a sensor. The pacer automatically selects between the indicated rates to determine the best pacing rate for appropriately satisfying metabolic demand at all times. The natural rate, driven by the sinus node, takes precedence over the metabolic indicator rate, provided the natural rate meets a standard determined by the metabolic demand indicator rate.

Abstract: A non-invasive method and apparatus for monitoring individual lung function is disclosed. A transducer (12, 14) is disposed on the torso above the lung to be monitored, the transducer producing a signal corresponding to movement of the torso portion therebeneath which, in turn, corresponds to changes in the volume of the underlying lung. Regional lung volume changes may also be assessed by utilizing transducers positioned on the torso to encompass only a portion of the underlying lung.

Abstract: A method and apparatus for increasing the blood flow in a patient's tissue by warming the tissue with heat generated by a semiconductor device mounted in a sensor. The amount of heat generated is controlled by varying either the magnitude or the duty cycle of the current that flows through the semiconductor device, with the amount of heat required determined by either the temperature of the sensor's contact surface or the operating performance of the apparatus.

Abstract: An implantable device prevents tachyarrhythmias of a human heart which has arrhythmogenic tissue such as a myocardial infarction site. The device includes a plurality of electrodes configured for electrical contact with the heart and for placement in proximity to the arrhythmogenic tissue and a sensor including a single sensing electrode for sensing electrical activations of one chamber of the heart. A pulse generator coupled to the plurality of electrodes and responsive to the sensor provides the plurality of electrodes with an electrical pulse during each sensed electrical activation.

Abstract: A universal fitness testing system (10) that allows individuals to determine their aerobic fitness in 30-seconds. The system (10) functions with two inputs: the first is a set of pulse-rate digital signals corresponding to the pulsations of the individual's cardiovascular system. These signals are derived by performing a 30-second test that ultimately produces a uniform work load (14). The second input is a set of user-specific digital signals corresponding to the individual's age, body weight and sex that are manually inputted and processed by an electronics keyboard (36). The two signals are processed and conditioned by an electronics unit (18) before being applied to a microcomputer (12). The microcomputer with its operational program processes the signals to derive the individual's equilibrium heart rate (12b) that is then corrected by sex and age standards (12c) and Vo.sub.2 max standards (12d), (12e) to produce fitness scores and categories. The corrected equilibrium heart rate also produces % Vo.sub.

Abstract: A rate responsive cardiac pacemaker for providing an optimized pacing rate of stimulation pulses as a function of at least one selected rate control parameter. Each rate control parameter has a value which varies as a function of changes in a patient's physiologic demand an includes a sensor system for sensing the rate control parameter value and for providing a sensor output representative thereof. The cardiac pacemaker also includes control circuitry which includes a rate response defining means for deriving desired pacing rates as a function of the sensor output and an achievement monitoring means that has a predetermined achievement criterion, for monitoring the relationship between the derived pacing rates and the achievement criterion over an achievement output. An output circuitry provides optimized pacing rates as a function of the desired pacing rates; and a rate response control means adjusts the rate response defining means accordingly.

Abstract: A diagnostic monitor checks the carbon dioxide (CO.sub.2) content of a gas exiting a patient during endotracheal or esophageal intubation. A plurality of composition portions substantially change color in response to exposure to the carbon dioxide. The composition portions change color in response to different times of exposure to carbon dioxide. A magnifying or condensing lens may be positioned on the monitor to enhance viewing of the color change. The monitor may advantageously be made part of an intubation system through which the gases from a patient exit the patient. The differences in time of exposure needed to cause the color change may be accomplished by using semipermeable membranes having differing thicknesses, CO.sub.2 permeabilities, and/or surface areas with each membrane corresponding to a particular one of the composition portions. An arrangement is provided whereby the monitor is automatically activated by the normal assembly steps of a patient breathing circuit.

Abstract: A Doppler ultrasound transducer and interconnected high frequency signal processing circuit, adapted for operative coupling on a distal portion of an intravascular catheter, for ultrasonically sensing high frequency signals representative of blood flow within a patient's cardiovascular system, processing these high frequency signals into baseband audio signals, and communicating these audio signals to associated low frequency signal processing circuitry located in the proximal portion of the catheter by modulating the load current of a power supply within the high frequency circuit.