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To compute the heartbeat rate from the waveform output of an electrocardiogram, a digital cardiometer with solid state circuit elements has been developed. This computes the beat every 15 seconds and visually presents the data on numerical display tubes.
Physiological waveform simulator is capable of producing signals to simulate an axiliary and a sternal electrocardiogram, blood pressure, respiratory rate and body temperature. This may be used to check out bioinstrumentation.
Transistorized, portable, high performance amplifier with low power drain facilitates biomedical studies on mobile subjects. This device, which utilizes a differential input to obtain a common-mode rejection, is used for amplifying electrocardiogram and electromyogram signals.
Technique for simultaneous monitoring of diaphragmatic electromyogram and electrocardiogram in rats
Data acquisition instrumentation for heartbeat display in electrocardiogram
Circadian rhythms from electrocardiogram and cardiotachogram of patient with human heart transplant, noting P waves relationship between donor and recipient tissues
Atrioventricular conduction in the human heart, analyzing electrocardiogram response patterns recorded by electrode catheter in unanesthetized man
Application of information theory to eliminate redundant part of electrocardiogram or vectorcardiogram is described. Operation of medical equipment to obtain three dimensional study of patient is discussed. Use of fast Fourier transform to accomplish data compression is explained.
Newly designed electrode is prefilled, disposable, electrolyte-saturated spong. New design permits longe periods of storage without deterioration, and readiness in matter of seconds. Electrodes supply signals for electroencephalogram, electro-oculogram, and electrocardiogram.
The deconditioning effects of weightlessness on the cardiovascular system of astronauts are discussed. It is believed that man cannot tolerate indefinite exposure to weightlessness without considerable circulatory deterioration. Analyses of data collected from space flights to date substantiate these beliefs, and confirm the fact that some form of compensation must be provided to keep the cardiovascular system of space travelers properly conditioned. Sequential pulsatile devices were investigated to produce periodic hydrostatic pressure gradients in the venous system of eight subhuman primates. Intermittent venous pooling of blood in the extremities triggers and stimulates the vascular reflex mechanisms of the cardiovascular system that may have significant benefits in maintaining the circulatory system in proper tone under weightless conditions. Electrocardiograms, blood pressure measurements, cardiac output and stroke volume determinations were used to evaluate the efficiency of the described technique. Results were amazingly consistent to indicate an efficient system for intermittently exercising the heart within safe and medically acceptable limits.
Techniques developed to automatically process a large quantity of physiological data obtained during a 1000-flight study are described. To reduce this data reliably, a study program was conducted using physiological data from X-15 flights as a data source for experimenting with signal enhancement and noise elimination techniques. The techniques include an automatic means for counting heart rates, averaging electrocardiogram waveforms, plotting histograms of heart rate versus frequency, and counting respiration rates. These techniques were used to reduce more than 2000 hours of physiological data recorded in flight.
The effects of a fixed, intense, one-foot diameter beam of simulated sunlight imaged within the field of view, upon responses to a battery of visual, body balance and stability, eye-hand coordination, and mental tests were studied. Each subject's electrocardiogram and electro-oculograms (vertical and horizontal) were recorded throughout each two-hour testing period within the space-station-like environment. It is possible to say that both subjects adapted to the brightly illuminated white panels in approximately 30 seconds after their first exposure each day and thereafter did not experience ocular fatigue, eye strain, or other kinds of disturbances as a result of these viewing conditions.
A miniature biotelemeter has been developed for sensing and transmitting multiple channels of wideband biomedical data over a radio link. Its small size and weight make it capable of being carried by free-moving laboratory animals as small as rats. Ten data channels each of 5-kHz data bandwidth are provided to permit monitoring of a wide variety of physiological signals. Multichannel telemetry of electroencephalograms, electrocardiograms, electromyograms, state functions, and dynamic processes such as blood flow and body chemistry are possible applications. Utilization of newly available monolithic chip components, low-power COS/MOS MSI digital logic, and state-of-the-art hybrid mounting techniques makes this novel device useful for both research and clinical bioinstrumentation.
The gathering of surface potential profiles by computerized processing of electrocardiogram data is projected. These profiles are concerned with the detail of localized potentials on the human body and are obtained by voltages plotted against electrode positions with time as the variable held constant. Sample and hold circuits are considered for processing the multiplexed signal and to digitize and code it for the tape recorder.
Tolerance to positive g accelerations was measured in ten normal male subjects using both standard and advanced techniques. In addition to routine electrocardiogram, heart rate, respiratory rate, and infrared television, monitoring techniques during acceleration exposure included measurement of peripheral vision loss, noninvasive temporal, brachial, and/or radial arterial blood flow, and automatic measurement of indirect systolic and diastolic blood pressure at 60-sec intervals. Although brachial and radial arterial flow measurements reflected significant cardiovascular changes during and after acceleration, they were inconsistent indices of the onset of grayout or blackout. Temporal arterial blood flow, however, showed a high correlation with subjective peripheral light loss.
Sensor can be installed in left ventricle by means of procedures available for inserting catheter into an artery at body's extremities and manipulating it through vessel and past aortic valve. Metallic tines of device can be used as internal electrode for electrocardiogram.
A mechanical occlusive cuff controller suitable for blood flow experiments in space shuttle flights is described. The device requires 115 volt ac power and a pressurized gas source. Two occluding cuff pressures (30 and 50 mmHg) are selectable by a switch on the front panel. A screw driver adjustment allows accurate cuff pressurization levels for under or oversized limbs. Two pressurization cycles (20 second and 2 minutes) can be selected by a front panel switch. Adjustment of the timing cycles is also available through the front panel. A pushbutton hand switch allows remote start of the cuff inflation cycle. A stop/reset switch permits early termination of the cycle and disabling of the controller to prevent inadvertent reactivation. Pressure in the cuff is monitored by a differential aneroid barometer. In addition, an electrocardiogram trigger circuit permits the initiation of the pressurization cycle by an externally supplied ECG cycle.
To investigate the effects of physical training on cardiac dimensions and function, eight dogs were exercised for 12 weeks by treadmill running 1 hour/day, 5 days/week. Five dogs were confined in cages as controls for an 8-week period. Heart rates were monitored by telemetry during rest and exercise. Maximum QRS spatial magnitudes were calculated from records of McFee lead electrocardiograms. Left ventricular end-diastolic dimensions were determined radiographically by the bead and clip technique. Training produced statistically significant decreases in heart rate at rest and at a standard work load of 6.1 mph on a level treadmill and statistically significant increases in work load at a standard heart rate of 194 beats/min. Improvements were rapid during the first 4 weeks of training but gradual during the remaining 8 weeks. Training caused small but statistically significant increases in left ventricular end-diastolic wall thickness, estimated left ventricular mass, and maximum QRS spatial magnitude.