Abstract: A high-accuracy QRS detector detects "activity" on the ECG waveform. Activity results from a steep slope of one sense followed shortly thereafter by a steep slope of the opposite sense. Low-pass filtering activity and multiplying by 2.5 yields a noise threshold. An activity peak which rises above this threshold may be a QRS complex. The detector waits three-fourths the average R to R interval after detecting a peak to allow for greater peaks to be detected. If none are, the peak is confirmed if it is either at least half the magnitude of the previous peak, or if it occurs at least three-fourths the average R to R interval after the last detected peak. This high-accuracy detector may be coupled with a fast QRS detector by providing it with the peak values of the previous three detections. The fast detector will detect if the slope is greater than three-fourths the average of the previous three detections, greater than the noise threshold, and more than 160 ms has elapsed since its last detection.

Abstract: A sensor positioning aid includes a concavely curved transparent dish having a shape congruent with a lower surface of a sensor, and locating means on the dish for establishing external reference positions in relation to the dish. The locating means preferably includes a rim around the dish and markings on the dish. The positioning aid is placed at a selected location on the head, and the sensor is aligned to the head by aligning it to the rim of the positioning aid. The positioning aid is removed, and the head translated in relation to the sensor to place it closely adjacent to the sensor, without reorienting the sensor. The placement aid is removed and measurements are taken using the sensor. If necessary, the sensor is thereafter reoriented by reference to the markings.

Abstract: Neurological stimulation alleviates chronic pain and other functional neurologic disorders by delivering electrical impulses to the nervous system of a patient. Within this setting, a computer interface optimizes stimulation with commercially available neurostimulators. The computer and interface, in cooperation with a unique graphics input device, deliver arbitrary and unique paradigms of stimulation. The computer interface provides for efficient patient interaction, optimizes stimulation automatically, and reduces the demands imposed on the time of health care professionals.

Abstract: An integral catheter and blood tester includes a needle unit which is receivable within a conventional catheter intravenous tube and housing. The catheter supports a piercing needle and interior chamber. A transparent tester housing is coupled to the needle unit and supports a test strip and test patch which extends into the flash chamber of the catheter needle. A constricting valve surrounds the test strip to maintain closure of the flash chamber. Once the catheter and needle have been inserted into the desired blood vessel, a quantity of blood is introduced into the flash chamber so as to wet the test patch. The test patch may, for example, include conventional litmus material used to test the pH of the test sample. Once the flash process is complete, the needle and tester housing are withdrawn from the catheter to permit conventional intravenous coupling to the catheter. Thereafter, the tester housing is separable from the needle unit to permit discarding of the needle unit.

Abstract: Providing a sensitive, prompt, and accurate indication of both ventricular fibrillation and monomorphic ventricular tachycardia is the aim of this invention. The invention employs electrical voltage-versus-time signals produced by the heart, these observed from two or more locations. By well-known signal-processing techniques, these signals are reduced to pulses of standardized height and duration, each derived from a prominent feature of the waveform for each heart period, such as its leading edge, in the process eliminating the irrelevant information in the waveform, but retaining the feature that is most relevant in the present context, namely, its precise time of occurrence. The invention then uses further standard electronic techniques to determine the amount of delay between the corresponding pulses in two such pulse trains, in the process distinguishing between monomorphic ventricular tachycardia and more benign conditions.

Abstract: A medical monitor, such as a fetal monitor, is provided with a code reader, e.g. a bar code reader. A manual contains clear text instructions as well as predefined codes in their correct sequential form. The instructions help the unskilled user to operate the monitor, and the actual monitor functions are triggered by scanning the codes, instead of pushing buttons, turning knobs etc. A questionnaire may also be provided to enter answers to anamnesis data. These answers, together with vital signs data, may be transmitted via telephone lines to a hospital, which makes the medical monitor ideally suited for home monitoring applications.

Abstract: A method of and apparatus for telemetering analog and digital data transcutaneously between an implantable medical device and an external receiver, such as between an external programmer and an implantable cardiac pacer. A damped carrier at 175 kilohertz is pulse position modulated by digital data. The data, along with synchronization and identification codes, are positioned into predefined ranges within predefined frames as measured by individual time periods. The data is uniquely identified by the position of one or more bursts of the carrier within the predefined range. An automatically initiated hand shake protocol maintains the link over slight variations in programmer head position with an indicator notifying the operator when repositioning is required. Analog data may be transferred in digital form or alternatively transferred using phase modulation of the carrier bursts. A cyclic redundancy code is used for link error detection.

Abstract: Control of an anti-tachycardia device such as a defibrillator to apply a preselected programmed therapy in the event of ventricular tachycardia. The control includes comparison of the atrial and ventricular rhythms, and examination of the criteria of stability of the P-R intervals, of the stability of the R-R intervals, and of the acceleration of the ventricular rhythm subsequent to an atrioventricular desynchronization, thereby to ensure control of the antitachycardia device solely in the event of ventricular tachycardia.

Abstract: A controlled-rate, artificial cardiac pacemaker (14) comprises a module (12) for adapting the stimulation rate to the patient's actual physical load. In the case of limited or non-existent activity, the output signal of a sensor (10, 11) for the patient's activity status constitutes a control signal for a circuit (20) which reduces the energy supplied to the module for adapting the stimulation rate of the artificial cardiac pacemaker to the patient's actual physical load.

Abstract: A method of repairing a blood vessel having a narrowed portion therein comprising the steps of expanding the narrowed portion of the blood vessel so that the diameter of the blood vessel after expansion is enlarged; and then maintaining an electronegative potential on the interior surface of the expanded narrowed portion of the blood vessel to at least as great as any electropositive potential generated by the blood vessel as a result of the injury to the blood vessel caused by the expansion thereof.

Abstract: A pulsed high frequency current is fed to a bipolar diathermy instrument for optimum execution of a section in capsulotomy. The pulse duration can constantly be altered between 3 ms and 11 ms, whereby a pause of 30 ms or 22 ms develops. This pause is sufficient to cool the instrument tip, flushed with sodium chloride, in order to prevent the possibility of injury to adjacent tissue. The pulse repetition frequency is about 15 hz. The device necessary for the purpose includes pulse duration control (31) and HF oscillator (30). The HF current is synchronized by pulses from control (31) with AND gate (35). Amplifier (40) feeds handpiece (21) of the diathermy instrument by transformer (46). The required operation free from grounding is thereby assured.

Abstract: A method and apparatus for determination of battery end-of-service in a medical device in which the medical device comprises a cathode limited electrochemical cell having an active metal anode and a manganese dioxide cathode and means for digital telemetry of cell voltage. The sloped, well defined voltage curve of such a cell during cell discharge combined with precise information available through digital telemetry allows for improved determination of battery end-of-service for the medical device.

Abstract: An implantable medical device, such as a heart pacemaker, or defibrillator, has a welded capsule housing which is filled with a gas mixture containing helium, the helium permitting the detection of leaks in the capsule housing. To improve the electrical insulating properties, the remaining gas of the mixture is selected from a group of gases having electrically insulating properties, such as nitrogen, sulfur hexafluoride, carbon dioxide, or halogenated hydrocarbons.

Abstract: An apparatus for detecting, identifying and treating tachyarrhythmias. Tachyarrhythmias are detected and identified by the use of overlapping ranges of intervals. Provisional identification of tachyarrhythmia is accomplished by measuring and tracking intervals within two overlapping or adjacent interval ranges. Further classification and identification of tachyarrhythmias is accomplished by determining the relative numbers of intervals within a preceding series falling within a third interval range, overlapping one or both of the interval ranges. In response to identification of the tachyarrhythmia, an appropriate therapy is selected and delivered.

Abstract: An implantable physiologic device, e.g., a multi-programmable, microprocessor based cardiac pacemaker, is provided with data storage and transmission capabilities for transmitting out certain current operating parameters and sensed events and for storing counted events for transmission of counts, histograms and real-time clock data out on command. The device preferably comprises 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 and includes a sensor system for sensing the rate control parameter value and for providing a sensor output representative thereof.

Abstract: A cardiac pacemaker signal processing circuit adapted to obtain an evoked ECG signal. The circuit senses the electrical signals of the ring and tip electrodes in the unipolar mode from the bipolar lead after the electrical pacing stimulus has been applied to contract the ventricle of the heart. The residual oppositely polarized potentials at the ring and tip electrode, as well as the sensed evoked ECG signals, are added together to cancel out the opposing residual potentials, but to add the common polarized ECG signal. Thus, a high quality evoked ECG signal is obtained, free of the residual potentials, and subsequently utilized by R-wave detection circuits for sensing the QRS complex. The circuit includes compensating signal processing circuits to provide time domain signal processing weighting functions to match exponential time delay of the tip and ring electrodes, and includes amplitude adjusting compensation as well.

Abstract: A method of and apparatus for telemetering both analog and digital data transcutaneously between an implantable medical device and an external receiver, such as between an external programmer and an implantable cardiac pacer. A damped carrier at 175 kilohertz is pulse position modulated by digital data. The data, along with synchronization and identification codes, are positioned into predefined ranges within predefined frames as measured by individual time periods. The data is uniquely identified by the position of a burst of the carrier within the predefined range. An automatically initiated hand shake protocol maintains the link over slight variations in programmer head position with an indicator notifying the operator when repositioning is required. Analog data may be transferred in digital form or alternatively transferred using phase modulation of the carrier bursts. A cyclic redundancy code is used for link error detection.

Abstract: A photo-electric pulse measuring probe includes a pair of supporting members which have a light emitting element and a light receiving element adjacent first end portions thereof, respectively, in such a manner that the light emitting element and the light receiving elements are confronted with each other, and which are swingably coupled to each other at the other end portions thereof. The light emitting element and the light receiving element are covered with elastic members, respectively, and wavy surfaces are formed in the mating surfaces of the elastic members, respectively, so that a user's finger is supported by a number of points during measurement.

Abstract: In order to terminate pacemaker-mediated tachycardia (PMT), a pacemaker (or "Pacer") capable of atrial synchronized ventricular pacing, defines a retrograde sensing window after a ventricular paced event. If a preset number of sequential retrograde sensed events occur within this window in consecutive pacing cycles the post ventricular atrial refractory period (PVARP) is extended for one pacing cycle (EXT PVARP) and the pacer will not attempt to interrupt a PMT for a relatively long preset interval thereafter.

Abstract: A waking degree maintaining apparatus of this invention estimates a waking degree of a person on the basis of a correlation between brain waves and the reaction time or between the blinking frequency and the reaction time, and discriminates a drop in waking degree on the basis of the obtained waking degree. A stimulus according to the waking degree is presented to maintain the person in a waking state of a predetermined level. The waking degree of a person is recovered to a normal state, not only in a low waking degree state, but also in an over-stained state.