SU982702A1 - Device for investigating myocardium stimulation threshold - Google Patents

Description

(54) DEVICE FOR RESEARCH OF MYOCARDIAL REFRACTIVE THRESHOLD

one

This invention relates to medical technology, namely, cardiac pacemakers.

A device for studying the myocardial irritation threshold is known, which contains electrodes, indicators and a generator of paired pulses, which includes a master oscillator and a fixed delay circuit 1.

However, this device does not allow to determine when a stimulating impulse reaches a value sufficient for excitation threshold, and measuring the myocardial irritation threshold by stimulating the heart with a single impulse of reduced amplitude is associated with a danger to the patient's life, as well as determining the threshold irritation at the time of termination of the rhythm of the heart.

The closest in technical essence to the present invention is a device for studying the myocardial irritation threshold, which contains electrodes connected through a protective circuit to the first and second output stages and the first indicator, which drives a generator connected through series-connected delay elements, the first duration regulator and the first regulator the amplitude torus to the first output stage, the second duration controller connected via the second amplitude controller to the second output stage pulse sensor

5 oscillations, which are connected via series-connected amplifier, shaper, and coincidence element to the second indicator, an adjustable delay unit whose output is connected to the second input element of the coincidence element, and the input is connected to the output of the master oscillator and to the input of the second regulator of duration 2.

However, the known device does not provide an accurate determination of the myocardial irritation threshold due to the discrete nature of the measurement process, the response of the indicator with a delay of 200-300 ms and the presence of a hysteresis of the stimulation threshold, while the measurement time is 15-20 seconds.

The aim of the invention is to increase the accuracy of determining the threshold of irritation of the myocardium during the destruction of the measurement time.

This goal is achieved by the fact that, in a device for examining a threshold for irritation of the myocardium, containing electrodes connected through a protective circuit to the first and second output stages and the first indicator, a driving generator connected through a series-connected delay element, the first regulator of duration and the first regulator of amplitude to the first output stage, the second regulator of duration, connected through the second regulator of amplitude to the second output cascade, the sensor of pulse fluctuations, which is connected through Consequently, an amplifier, a driver, and a matching element to the second indicator, an adjustable delay unit whose output is connected to the second input of the matching element, and an input connected to the output of the master oscillator and to the input of the second duration regulator, are inserted a trigger, a start button, a D / A converter, sequentially the connected key, the counter and the decryptor are two porous transmission elements, the first inputs of which are connected to each other and to the output of the decoder and are serially connected a register, an information output unit and a digital display, the register output being connected via a digital-to-analog converter to the second input of the second amplitude controller, the first input to the output of the first bit transmission unit, the second input to the output of the second bitwise transmission element, and the third input with the second output of the information output unit, with the second input of the counter, and with the first trigger input, the second input of which is connected to the start button, and the output to the first input of the key, the second input of which is connected to the output of the generator, and an output coupled to a second input of the first bit-wise transmission element, wherein the second input of the second bit-wise transmission element connected to the output of matching element.

The drawing shows a block diagram of a device for studying myocardial irritation threshold.

The device for examining the myocardial irritation threshold contains electrodes 1 connected via a protective circuit 2 to the first and second output stages 3 and 4 and the first indicator 5, the master oscillator 6 connected through a series-connected delay element 7, the first duration regulator 8 and the first regulator 9 amplitudes to the first output stage 3, the second regulator 10 duration, connected through the second regulator 11 amplitude with the second output stage 4, the sensor 12 pulse oscillations, which is connected through in series connected amplifier 13, driver 14 and coincidence element 15 to the second indicator 16, adjustable delay unit 17, the output of which is connected to the second input of coincidence element 15, and the input connected to output of the bis master oscillator by the input of the second duration regulator 10, while trigger 18, start button 19, digital-to-analog converter 20, a key 21 connected in series, a counter 22 and a decoder 23, two bit-transmitting elements 24 and 25, the first inputs of which are interconnected and with the output of the decryption 23 and serially connected register 26, information output unit 27, and digital display 28, the output of register 26 being connected via a digital-to-analog converter 20 to a second input of a second amplitude regulator 11, a first input to an output of a first transmittance 24, the second input with the output of the second bit-transmitting element 25, and the third input with the second output of the information output unit 27, with the second input of the counter 22 K with the first input of the trigger 18, the second input of which is connected to the start button 19,

5 and the output is connected to the first input of the key 21, the second input of which is connected to the output of the master oscillator 6, and the output is connected to the second input of the first element 24 of alternating transmission, while the second input of the second element 25 alternating

 the transmission is connected to the output of the coincidence element 15.

The device works as follows.

5 The device is connected to the heart implanted electrode 1, and a pulse pulse sensor 12 is put on the patient's finger. The pulses from the master oscillator 6 are delayed by a delay element 7 for 100-120 ms, formed by the duration of the first regulator 8 duration and through the first regulator 9 amplitude and the first output stage 3 arrive at the first indicator 5 and the protective circuit 2. At the same time, the delayed amplitude

5 pulses is 7-9. In the case of a duration of 2 ms, which guarantees a significant excess of the threshold of irritation of the myocardium and, consequently, effective stimulation of the heart. Through the protective circuit 2 and the electrodes 1, the pulses arrive at the heart, causing it to contract with the frequency of generation of pulses in the generator 6. At the same time, the pulses from the master oscillator 6 are formed by the duration of the second regulator 10 and are fed to the second regulator 11 of the amplitude, which is controlled by a digital-analogue converter 20. In the initial state, the output of the digital-to-analog converter 20 is zero voltage level, and the output

the second regulator 1 amplitude no pulses. After pressing the start button 19, the trigger 18 opens the key 21 and the pulses from the master oscillator b begin to arrive at the counter input 22 of the number of balancing cycles. With the arrival of the first pulse from the generator 6, the decoder 23 will select the first position in the 24-bit transmission elements 24 and 25 corresponding to the older bits of the register 26, and the signal from the output of the key 21 through the bit-transmission element 24 will pick up the unit in the high-order register 26. The output of the digital-to-analog converter 20 is Vits, the voltage corresponding to half the value of the measurement scale. The time for establishing the voltage at the output of the amplitude controller 11 from the moment of arrival of the pulse from the master oscillator 6 does not exceed 10 µs. The pulse received from the output of the regulator 11 is amplified in power by the output stage 4, and the passage through the protective circuit 2 enters the implanted electrode I. If the amplitude of this measuring pulse exceeds the value of the myocardial stimulation threshold, the heart will contract. The pulse wave signal caused by the contraction of the heart is removed from the patient's hand by the pulse oscillation sensor 12, amplified by the amplifier 13, formed by the shaper 14 and fed to the coincidence element 15, to another input of which a generator pulse 6 delayed by the adjustable delay unit 17 is received . Thus, in the presence of a cardiac collapse caused by a measuring pulse, at the output of the element: 15 coincidence, the signal that is fixed by the indicator 16 and through the bit-transmitting element 25 will enter the reset input of the high-order register 26 and return it to its original state . In this case, the digital-to-analog converter 20 will return to the initial state. After 100–200 ms after the beginning of the measuring pulse on the heart, the pulse delayed by the delay element 7 will fall, which will fall into the absolute refractory period of the cardiac cycle and will not cause a reduction in ce. In the case when the amplitude of the measuring pulse is less than the threshold of stimulation of the myocardium, the heartbeat does not occur, at the output of element 15 there is no signal and there is no reset of the most significant bit of register 26. However, the continuity of the process of electrical stimulation of the heart is not disturbed. Its continuity is ensured by a pulse delayed by delay element 7, which has parameters sufficient to stimulate the heart. Second (after pressing the start button 19)

the pulse from master oscillator 6 will change the state of the counter 22 equalization cycles and the decoder 23 will switch the elements of 24 and 25 random transmission to the polling position of the next register bit 26. At the output of the digital-to-analog converter 20, depending on the result of the previous weighting, the voltage is equal to or 1/4 of the entire scale (if the amplitude of the previous measuring pulse is equal to 1/2 of the entire scale exceeds the threshold of myocardial irritation) or (1/2 + 1/4) of the whole scale (if the amplitude of the previous measuring pulse is not elevated myocardial irritation threshold). The measurement process then proceeds as described above until all the bits of the n-bit register 26 are polled. Thus, the value of the threshold value of myocardial stimulation with a sampling error of 1/2 of the measured values will be written in the binary code in register 26. . The end of the measurement cycle fixes the decoder 23, producing a signal to the information output unit 27, which reads the binary information from the register 26 and converts it into the number of pulses fixed by a three-decade digital display 28, i.e. the true value of the stimulus threshold is output. After the end of the readout at the output, the end of the readout of the information output unit 27 on the wits reset pulse, which returns to its initial state the register 26, the counter 22 of the balance cycles and the control trigger 18.

The proposed device improves the accuracy of determining the myocardial irritation threshold by eliminating subjective measurement errors and shortens the measurement time (at a generator frequency of Bp / min, the measurement time is 8 s, and at a frequency of 120 imp / min - 4 s), which leads to a decrease in the number repeated measurements necessary to determine the average statistical value of the myocardial irritation threshold, which allows relief of medical personnel and less traumatizing the patient's heart during the measurement process.

Claims (2)

1. Electrostimulator torr “Spectron-1 - Sat. “Descriptions of the scientific principles of the device of new devices and methods of using them. Section "Electrophysiological equipment, Pushchino," Scientific Center for Biological Research, USSR Academy of Sciences, 1974. 2. USSR author's certificate number 787040, cl. A 61 N 1/36, 1980.