Abstract: An ambulatory physiological computer recorder that includes multiple selective plug and play signal input conditioners, a microprocessor system with operating and analyzing software and a removable memory module for data storage. The removable memory module may consist of any non-volatile memory such as IC memory, magnetic memory, optical memory or magneto-optical memory. The removable memory module used in the recorder excludes operating software; the purpose of the removable memory module in the recorder is only to receive and store acquired data. The recorder uses an alpha-numeric LCD display with control buttons for user interface to enter patient ID and recorder functional perimeters. Both operational and selective analysis software is resident in the microprocessor EEPROM memory. Software is installed in the recorder by transfer from an external source via standard serial or parallel links with applicable connectors, or by a plug-in EEPROM.

Abstract: A method and apparatus for an ambulatory electrocardiographic monitoring system for recording, detection, measurement, analysis and plotting of high resolution electrocardiographic data having a modified Holter recorder that performs digital signal averaging of selected signals as well as storing for future playback all ECG beats. The digitally signal averaged beats are correlated with a previously defined correlation coefficient yielding summated results that have eliminated nonrepetitive noise to less than a microvolt. By real time averaging approximately 1000 beats during a 10 to 15 minute period and digitally storing the averaged data, micropotential averaging can be performed several times per hour for up to 24-hours. Analog recordings are precalibrated for accurate amplitude representation as well as providing an option for standard one millivolt calibration pulses at the beginning of the tape.

Abstract: Method and apparatus for arrhythmia analysis of Holter-type ECG recordings including a tape playback unit having an analog signal output of successive ECG complexes or heart beats, a converter for generating data composites representing each complex, a computer for making and storing data templates in bins corresponding to operator classification of complexes as normal, supraventricular ectopic (SVE), ventricular ectopic (VE), or unknown, for comparing successive composites with stored templates and conditions to determine a match condition, and for signaling a corresponding event to an event counter and display. In learn mode the computer signals the tape playback to stop and to display an unmatched complex for operator classification and possible subsequent generation of a new template, after which scanning is resumed.

Abstract: Apparatus is disclosed for long-term ambulatory monitoring of blood pressure by an auscultation method, employing a pressurizable cuff and requiring no intervention by the patient. Heartbeats are sensed by ECG electrodes, and a microphone is used to sense the Korotkow sounds as the pressure in the cuff is varied. The presence or absence of a Korotkow sound within a preset interval following each heartbeat is used in determining when the cuff pressure equals the systolic and diastolic pressures. Those pressures are determined in each cycle of operation and are recorded on a continuously-running portable tape recorder, along with the ECG signals. In each cycle of operation, the initial pressure to which the cuff is inflated is based on the systolic pressure measured in the immediately preceding cycle. The pressure in the inflated cuff is thereafter stepped downward in small discrete decrements triggered by successive heartbeats during the measurement phase of each cycle.

Abstract: ECG signals from two approximately orthogonal leads are combined in a rectangular-to-polar coordinate converter to obtain signals representing the magnitude and angle of the vector. The vector angle existing at the instant the magnitude of the QRS vector reaches its peak is first identified, and a voltage corresponding to the vector angle is sampled and stored for later use. Secondly, the vector angle existing at the instant the magnitude of the T-wave vector reaches its peak later in the cardiac cycle, is identified, and a voltage corresponding to this second vector angle is sampled and stored. The voltages representing the QRS and the T-wave vector angles are then applied to a differential amplifier to obtain a difference voltage representing the angular difference existing between the two maximal vectors. This angular difference possesses certain characteristics which are diagnostically significant. A classifying circuit determines which one of a number of angular ranges the angular difference falls into.

Abstract: A miniature tape recorder intended for ambulatory recording of cardiac signals over a twenty-four-hour interval includes a clock with a visual display and an event marking circuit. Cardiac signals are recorded simultaneously on two tracks on the magnetic tape used by the recorder. The event marking circuit, activated by the patient, interrupts briefly the recording of cardiac signals on one of the tracks to record in its place an event marker signal easily recognizable on playback. The event marking circuit includes a clock circuit, a counter, and logic circuits to generate a burst of exactly eight square pulses of predetermined width, the duration of the burst being one second.

Abstract: A multi-speed ECG magnetic tape scanning device for processing and observing in a relatively short interval of time large quantities of ECG signals from two pairs of ECG leads. The ECG information is recorded on a miniature recorder which the patient carries to record the information for a long period of time, such as 24 hours. The recorder includes a built-in clock with a visible display. The recorder also includes an event marker, which is activated by the patient when the patient experiences an event. The play-back of the ECG information is in real time or at multiple high speed play-back speeds of 30, 60 and 120 times real time. During play-back at high speed, a multi-speed multi-channel paper writer reproduces analog trend data, digital printed data and event marking. The trend information is usually heart rate and ST segment level, so as to produce a scanning of an entire 24 hour information tape in as short a period as 12 minutes.