SU827076A1 - Device for determining threshold of ventricular fibrillation in experiment - Google Patents

Description

one

The invention relates to medical technology, namely to electrical stimulators of biological objects.

A device for determining the ventricular fibrillation threshold in an experiment is known, comprising a discriminator, a former, a ventricular fibrillation recording circuit, and a light signaling unit 1.

A disadvantage of this device is the lack of accuracy in conducting the experiment.

The purpose of the invention is to improve the accuracy and reduce the time of the experiment.

For this purpose, a mode block whose inputs are connected to a discriminator, a driver and a fixing circuit, a generator, a reference block and a block of current intervals, the inputs of each of which are connected to the discriminator, a driver, a generator, a block of modes and a fixing circuit, a comparison circuit, are entered into the device. a code-voltage converter connected in series, a decoder connected to the alarm unit, and a cycle counter associated with the mode unit and the discriminator, the comparison circuit being connected to the reference and current intervals and the converter, and the fixing scheme with the discriminator input,

moreover, the alarm unit is made in the form of a light panel.

FIG. 1 shows a block diagram of the device; in fig. 2 - time diagram.

The device contains a discriminator 1, a pulse width former 2, a pulse generator 3, an operation mode determination unit 4, a unit 5 reference intervals, a unit 6 current intervals, a count of 7 cycles, a ventricular fibrillation fixation circuit 8, a comparison circuit 9, a decipheror 10, And converter the code-voltage p electronic scoreboard 12. The discriminator 1 and the pulse shaper 2 are connected to the operation mode determination unit 4, the reference intervals block 5, the current intervals block 6 and the ventricular fibrillation circuit 8. The inputs of blocks 5 and 6 of the reference and current intervals and the scheme 8 for fixing the fibrillation of the ventricles receive signals from the generator of 3 pulses. The operation mode determination unit 4 is connected to the units 5 and 6 of the reference and current intervals, the counter of 7 cycles and controls their operation. The output of the counter 7 cycles is connected to the decipheror 10, the signal from which is fed to the code-voltage converter 11 and the electronic board 12. Blocks 5 and 6 of the reference and current intervals 3

yen with comparison circuit 9, which starts the converter AND code-tension and generates a control signal at block 6 of the test intervals. The output signal of the converter code-11 voltage is connected to the test object.

The device works in the following way.

The electrocardiographic signal arrives at the discriminator 1, which generates synchronization pulses at the time of passing the teeth R of the electrocardiogram, and the shaper 2 of duration, forming pulses whose duration corresponds to the duration of the teeth R and T of the electrocardiogram. The discriminator and imager signals are sent to the operation mode determination unit 4, which selects the first cycle of the electrocardiogram and delivers the enabling signal to the reference interval unit 5. At the input of the unit 5 of the reference intervals, the outputs of the discriminator 1 and the driver 2 are also set, which ensures the passage of a series of pulses from the generator of 3 pulses to one of the block counters from the leading edge of the R wave of the electrocardiogram to the leading edge of the T wave, and to the other of the block counters in the time interval equal to the duration of the T wave of the electrocardiogram. Thus, in block 5 of the reference intervals in the first cycle of the electrocardiogram, the duration of the interval from the leading front of the R-wave of the electrocardiogram to the leading front of the T wave and the duration of the T wave are memorized. These cycles are counted by a counter of 7 cycles and, through a decoder 10, are fed to the converter 11, the code-voltage and the electronic board 12. At the time of the passage of the R electr okardiogrammy signal amplitude shaper is supplied to block current intervals b and permits passage of a series of pulses with a pulse generator 3 for one block of the counters. As soon as the value of this counter coincides with the value of the corresponding counter in block 5 of the reference intervals, the comparison circuit 9, to which the signals from these counters are assigned, outputs a control signal, to the converter 11 code-voltage and block 6 of the current intervals. With the arrival of this signal, a signal appears at the output of the converter 11, the amplitude of which corresponds to the code recorded in the counter of 7 cycles, i.e. the number of cycles of the electrocardiogram. The same signal from the comparison circuit 9 is fed to the input of block 6 of current intervals and resets the first counter of block 6 of current intervals, permitting the passage of a series of pulses from the generator 3 emuls to the second counter of block 6 of current intervals. The output of that counter is set on the comparison circuit and when the counter value coincides with the value of the corresponding counter in the 5 reference intervals block, the comparison circuit 9 generates a second control signal that resets the counters of the 6 current intervals block and arrives at the code-eg converter 11 This will cause the output of the converter to be reset. Thus, the code-voltage converter 11 generates a signal with a duration equal to the duration of the T wave of the electrocardiogram, and with amplitude proportional to the number of cycles of the electrocardiogram, which is good from the beginning. the operation of the circuit.

Since the shaper 2 on the T wave of the electrocardiogram forms an imiuls, the duration of which is somewhat less than the duration of the T wave, after resetting the block 6 of the current intervals (from the comparison scheme 9) the first counter of the block 6 of the current intervals is not set to zero, but is entered into the code depends on the selected frequency of the generator 3 pulses. By initial reset of all counters

the stimulator produced manually before the start of work, the same code is entered into the second counter of the block 5 reference intervals, which leads to the output pulse from the converter 11, the voltage being generated a little earlier, and reset later than the pulse generated by the shaper 2 of the T wave electrocardiogram, i.e., completely overlaps the wave

- Further, the presence of an output pulse at the output of the converter 11, the code voltage does not depend on the presence of a T wave in the electrocardiogram cycle. To understand how the device works

The timing diagram in FIG. 2, where Ci is an electrocardiographic signal; € 2 - discriminator output; Sz - output signal shaper duration; Ci is the output of a code-voltage converter. The stimulator function is stopped by the ventricular fibrillation circuit 8, which is given a series of pulses from the generator

3 impulses with a frequency corresponding to the lowest possible frequency of ventricular fibrillation, and with a former 2 impulse duration. When the frequency of a series of pulses sticking from a generator of 3 pulses, the frequency of pulses from a generator of 2 duration, i.e., when fibrillation occurs, the ventricular fibrillation circuit 8 produces a signal that causes the stimulator to stop

electrocardiographic signal to the stimulator) and reset all counters, except the counter 7 cycles. The counter value of 7 cycles, triggered on the electronic board 12, reflects the magnitude of the amplitude of the signal from the code-voltage converter 11, which caused fibrillation.

The device allows automatic determination of the distance from the R wave of the electrocardiogram to the testing pulse; to form this impulse up to the duration that overlaps the T wave; increase the amplitude of the testing pulse per unit of measurement in each subsequent ECG cycle; fix the occurrence of ventricular fibrillation and stop the functioning of the stimulator, and ensure the formation of a testing pulse in subsequent cycles of the electrocardiogram in the absence of a T wave.

Claims (1)

Invention Formula A device for determining the ventricular fibrillation threshold in the experiment, comprising a discriminator, a former, a ventricular fibrillation recording circuit, and a light signaling unit, characterized in that, in order to improve the accuracy and reduce the experiment time, a mode block whose inputs are associated with discriminator, driver and fixing circuit, generator, reference block and block of current intervals, inputs of each of which are connected to the discriminator, driver, generator, mode block, and circuit encoding, a comparison circuit, a code-voltage converter connected in series, a decoder connected to the alarm unit, and a cycle counter associated with the mode unit and a discriminator, while the comparison circuit is connected to the reference and current interval blocks and the converter, and the fixing circuit is the discriminator input, moreover, the alarm unit is made in the form of a light panel. Sources of information taken into account in the examination 1. Titov V.N. and others. A parallel study of the thresholds of fibrillation and excitation of the ventricles of the heart in an experiment on animals. Cardiologists, 1977, vol. 17, No. 4, p. 11.2.