Showing papers on "Heartbeat published in 1971"

Fetal heartbeat monitoring system with plural transducers in one plane and at different angles thereto

Abstract: Fetal heartbeat monitoring system in which a plurality of ultrasonic beams are transmitted at different angles into the uterus of an expectant mother. A plurality of receiving transducers are inclined at different angles for receiving the signal as it is reflected from the fetus and/or uterus walls, the frequency of the reflected signal differing from that of the transmitted signal by an amount corresponding to the rate of the fetal heart motion. A system of rate computation from the resultant doppler fetal heart motion signal is employed which utilizes frequency domain techniques. The heart rate signal is extracted from the doppler heart motion signal by means of a diode demodulator and low frequency band pass filter.

Equipment for measuring and displaying the time lapse between a given heartbeat and the corresponding arterial pulse

Abstract: An apparatus for measuring the time interval between a heartbeat detected by an electrocardiographic detecting system and the corresponding peripheral pulse detected by a pulse sensing system is disclosed. Further features include a battery supply with a charging circuit and battery condition indicating means and a capacitor-type sample and hold circuit with constant current charging means and meter readout calibrated in pulse propagation time.

Automatic threshold compensating demand pacemaker

Abstract: In a demand cardiac pacer having means for providing periodic stimulating pulses to the heart, means for sensing natural heartbeats, and means for inhibiting the stimulating pulses on the occurrence of natural heartbeats, the improved apparatus including means for sensing stimulated heartbeats, means for decreasing the amplitude of a succeeding stimulating pulse on the occurrence of a stimulated heartbeat and means for increasing the next succeeding stimulating pulse by a predetermined amount on the failure to sense a stimulated heartbeat.

A mathematical model for ECG wave forms and power spectra

Abstract: It is desirable to construct a mathematical model that will accurately reproduce the discrete waves of an electrocardiograph signal. The usual cycle for one heartbeat includes a P wave (atrial depolarization), QRS waves (ventricular depolarization), and T wave (ventricular repolarization). The model presented simulates real or observed ECG signals and has many practical applications.

Ultrasonic doppler fetal heart monitor with variable resonance means

Abstract: Ultrasonic apparatus for monitoring heartbeat activity from Doppler shifted information derived from heartbeat motion comprising deriving the Doppler shifted information, which is fed to an adjustable resonant circuit for de-emphasizing Doppler signal frequency content other than that about the resonant circuit frequency, and comparing input signals to and output signals from the resonant circuit for detecting a phase difference, if any, which is employed for adjusting the frequency of the resonant circuit at a preselected rate.

Constant energy heartbeat stimulating apparatus with pulse width control

Abstract: Pulse-width controlled heartbeat stimulating apparatus. The apparatus includes an electrical power supply and a pulser for generating stimulation pulses on terminals connected to a patient's heart. An integral control is provided for automatically varying the width of the stimulation pulses as a function of the power supply (energy source) value to maintain the energy output above a predetermined level. The present invention can be used with many types of heart simulating devices including extra-corporeal pacers, but is particularly useful when utilized with non-accessible or implanted pacers. In an illustrative embodiment, a circuit is provided for indicating the approximate amount of remaining power supply life and for controlling energy supplied to the heart with each stimulation pulse to greater than a minimum required value regardless of energy source variation.

Diagnostic apparatus for fetal heartbeat monitoring

Abstract: The invention relates to diagnostic apparatus including an ultrasonic transmitter and an ultrasonic receiver. The beat signal is passed through a filter to select a particular frequency which occurs once in each heartbeat cycle. A voltage is produced proportional to the time interval between adjacent pulses of this particular frequency and a second train of pulses having a much higher repetition frequency is produced, the frequency of this second pulse train varying inversely with said voltage. The second train is applied to two pump circuit, one of which produces a signal representing the instantaneous frequency of this pulse train and the other of which produces a signal representing the average value of this frequency. The instantaneous signal is applied to a track/store amplifier which is changed over from its tracking function to its storage function when the difference between the instantaneous and average values exceeds a predetermined minimum.

Adaptive demand pacer

Abstract: A rate-adaptive demand pacer for stimulating the heart of a patient. The pacer senses or monitors the patient's varying natural heartbeat rate and varying natural escape interval of the heart. The pacer controls generation of heart stimulating impulses at a rate which conforms to the patient's last sensed natural heartbeat rate and escape interval. The initial rate of stimulation applied to the heart is controlled to be within a small predetermined rate difference from the last sensed natural heartbeat rate. Thus, sudden large variations in heartbeat rate are avoided when changing from a natural heartbeat condition to a stimulated heartbeat condition.

Heartbeat rate measuring apparatus

Abstract: Apparatus for determining the heartbeat rate of a patient comprising deriving electrical signals representative of heartbeat activity. The signals are converted by a function generator into a value indicative of heartbeat activity on a beat-to-beat basis, and, at least three successive ones of the values are compared by a pair of credence checkers having a preselected frequency tolerance. The values lying outside the tolerance are rejected. Passed values are averaged and displayed and a visible indication denotes occurrence of a nonpassed value.