SU1301377A1 - Apparatus for revealing cardiac arrhythmia - Google Patents

Abstract

The invention is intended to analyze the rhythm of heart contractions and allows to increase the reliability of detecting cardiac rhythm disturbances by allowing operative control of the operability of the main components of the device. The electrocardiogram PS3 that is removed from the patient being examined by the sensor 1 is output to the extraction unit 2, which for each R-wave forms a normalized sync pulse. When the device is switched to diagnostic mode using switch 8, the sync pulses go directly to the RR-interlock processing unit 3, which detects arrhythmias, the presence of which is indicated by the display unit 4. In the health check mode, the input of the R-teeth extraction unit 2 receives an irregular clock sequence of sync pulses generated by a delay block 6 and the element OR 7. If the control indicator 5 signals the presence of arrhythmia, detected by the RR intervals processing block 3, this indicates the normal operation of the main units of the device and, thus, the reliability of the information about the nature of heart rate obtained using the device. 1 hp ff. 5 il. i (L with figure 1

Description

The invention relates to medical technology, namely, devices for diagnosing diseases of the cardiovascular system.

The purpose of the invention is to increase the reliability of detecting cardiac arrhythmias by controlling the release of R-teeth and processing RR-intervals.

Figure 1 shows the structural electrical circuit of the device proposed; figure 2 is the same, the preferred option; in FIG. 3, a subtraction node; figure 4 - generator command pulses; FIG. 5 shows timing diagrams for the proper functioning of the device.

The device for detecting cardioarrhythmias contains (FIG. 1) serially connected electrocardiogram sensor 1 (ECS) and allocation unit -2 R-toothB, unit 3 for processing RR intervals, display unit 4, control indicator 5, series-connected delay unit 6 and the element OR 7, the second input of which is connected to the output of the R-teeth extraction unit 2, and the output - to the input of the RR-intervals processing unit 3, and a switch 8, the first input of which is connected to the second input of the OR element 7, the second input - with the output block 3 processing RR-intervals, the first output with stroke delay unit 6, a second output - to an input of the display unit 4, and the third output - to an input of a control indicator 5.

In this case, the delay unit 6 contains (FIG. 2) a series-connected pulse generator 9, the first element AND 10 and a pulse counter 1 1, the output of which is the output of the delay unit 6, has eaten randomly connected generator 12 and the second element And 13 The output of which is connected to the second input of the pulse counter 11, and the trigger 14, the output of which is connected to the second input of the first element 10, the first input to the output of the counter 1; 11 and 11 second pulses to the second input of the second element 13 block 6 input delay.

In a preferred embodiment of the device, the RR-intervals processing unit 3 comprises (Fig. 2) a pulse generator 15, a frequency divider 16, two pulse counters 17 and 18, a subtracting unit 19, a comparison element 20 and a control unit 21. Comparison element 20 may be implemented as a code comparator. The control unit 21 can be made in the form of a control pulse generator 22 and three triggers 23, 24 and 25, which form a pulse distributor with three outputs and a self-stop (figure 2).

The display unit 4 can be implemented, for example, on a pulse counter 26 connected in series (it is zeroed when the device is turned on), a decoder 27 and a digital indicator 28 (FIG. 2).

The subtractive unit 19 in the preferred embodiment contains (FIG. 3) a reversible pulse counter 29, a trigger 30, two AND 31 and 32 elements and an OR-NOT 33 element. The controlled command pulse generator 22 contains (FIG. 4) two triggers 34 and 35 And 36, a pulse generator 37 and a pulse shaper 38, made, for example, in the form of a differentiated RC circuit. Switch 8 may be implemented as two associated keys 8-1 and 8-2 (Fig. 2). The control indicator 5 is a light indicator made, for example, in the form of an indicator light.

5 The device for detecting cardiac arrhythmias works as follows.

The device has two modes of operation - the mode of diagnosis of arrhythmia and the mode of testing the operability of the device. In the diagnostics mode of arrhythmia with the help of switching bodies 8 (Fig. 5b, position I), the connection between the R-teeth extraction unit 2 and the delay unit 6 is opened, and the display unit 4 is connected to the output of the RR intervals processing unit 3. The EKS from sensor 1 (Fig. 5a) is fed to the input of an R-teeth extraction unit 2, which for each R-teeth EKS generates a square sync pulse (SI) fed through an OR element 7 to the input of a processing unit 3 of RR intervals (Fig .56).

The latter analyzes information about the time intervals between the pulses arriving at its input (figd) as follows. For each input pulse, the output of the flip-flops 23, 24 and 25 of the control unit 21 (FIG. 2) of the three control pulses K1, K2, and short-circuit (FIG. 5G) following the frequency determined by the controlled generator 22 is carried out sequentially. . The following operations are performed on the control pulses K1, K2, and short circuits in the RR-interval processing block 3; K1 is the comparison of codes in the reference element 20; K2 - rewriting the contents of the counter 18 to the subtraction unit 19; Short circuit - reset (set to zero) counters 17 and 18.

Clock pulses (TI) coming from

5 of the output of the generator 15 (Fig. 5e), are counted by a counter 18 and a counter 17, to the input of which TIs are fed through a divider 16 having a factor equal to, for example, five. Since the control pulses K1, K2 and short-circuit are produced with the arrival of

 each R-wave EX, at the end of each RR-interval, the counter 18 contains the value corresponding to the duration of the RR-interval, and the counter 17 contains a value equal to one fifth of this duration ..

The subtractive Node 19 determines the value corresponding to the absolute value of the difference of the durations of the previous RR interval RR, and the current RR interval RR, v i.

0

This is done by inputting the pulse K2 to the reversible counter 29 (FIG. 3) of the RR value from the counter 18, and simultaneously setting the trigger 30 to the single state. Next, the TI of the current RR interval entering through the AND input element is reversing counter 29, subtracts the duration RR, + i of this interval. If the difference reaches zero, the element ORID 33 generates a signal that resets the trigger 30, and the TI is fed to the input of the direct count of the reversible counter 29. As a result, the subtractor 19 determines the value

IARR, I IRR, -RR, +, |. (|)

On the control pulse K1, coming from the output of the control unit 21 to the comparison element 20, the value of lARRil is compared with the continuously varying control setpoint 0.2 RR; + i. When performing inequality

IARR.I o, 2 RR, +,

(2)

Comparison element 20 produces an impulse corresponding to the presence of arrhythmias of heart contractions.

The control pulse 13 resets the counters 17 and 18, completing the processing cycle of the current RR interval EX.

The pulses K1, K2 and KZ generated by the control unit 21 are tied in phase to the TI, i.e., they appear with the arrival of the first TI after the formation of the next SI (Fig. 5). This function is performed by controlled generator 22 (FIG. 3). Coming from the output of the element OR 7 SI (fig.5d) sets the trigger 34 into a single connection, which is rewritten into the trigger 35 after the occurrence of the next TI. At the same time, trigger 34 is reset. The trigger 35 during one TI period permits the passage of pulses from the generator 37 through the element 36 to the input of the controlled generator 22. At the time of the installation of the trigger 35, the driver 38 generates a pulse that is written to the trigger 23 by the strobe pulses of the generator 37, and is sequentially rewritten into triggers 24 and 25, producing, respectively, pulses K2 and CZ.

With the arrival of the next TI, the trigger 35 is reset and the control node 21 does not change its state until the next SI appears. Since the frequency of the generator 37 is not less than 3 times the frequency of the TI, control pulses are formed between the two first TIs following the SI, and the processing time of the RR interval EX does not exceed one TI period. In the presence of cardiac arrhythmias, detected by the RR-in treatment unit 3

five

0

0

five

0 5 5

0 5

Intervals, a pulse from the output of the comparison element 20 through the switch 8 is fed to the input of the display unit 4 (Fig. 2). This pulse increases by one the contents of counter 26, the output code of which is decrypted by decipher 27 and is indicated in decimal representation by digital indicator 28. At that, counter 26 starts its operation from the zero state set when the device is turned on.

In the device operability check mode, using the switch 8 (position I) the delay block 6 is connected to the output of the R-teeth extraction unit 2, and the control indicator 5 is connected to the output of the display unit 4 of the RR intervals processing unit instead of the display unit 4. To the input of the processing unit 3, RR intervals are fed through the element OR 7 both directly from the output of the extraction unit 2 by the R-wave, and after passing through the delay unit 6. Thus, in the test mode, the RR-interval processing unit 3 analyzes the verification rhythm, which is a combination of the patient's true rhythm of the patient and impulses that follow with a delay relative to the initial SI of the R-teeth EX-E (fig.5d). The resulting rhythm is altered, and the nature of the change depends on the delay time and on the true heart rate of the subject.

The delay time is determined by the statistical characteristics of the output of the generator 12 random numbers. Upon receipt of the SI at the input of the delay unit 6, the trigger 14 is set to one state, which ensures the passage of pulses from the generator 9 output through the AND 10 element to the counter 11. Preliminarily, the random number changing from the output of the 12 random numbers generator through the AND 13 element Therefore, the counter 11 counts the pulses from the output of the generator 9, starting with the number n, to the value of the conversion factor jV of the counter 11. The output signal of the counter 11, which is the output signal and the delay block 6, into the null state flip-flop 14 to inhibit the passage of pulses from the output of generator 9 via the AND gate 10 and permits entry through the AND gate 13, a new number n of random numbers generator 12 to the counter 11, setting the delay unit 6 to receive the next SI. The delay time of the delay block 6 is determined in accordance with the ratio

. 1z.

(3)

delay time unit 6 delay;

conversion factor of the counter 11;

the number entered into the counter 11 from the generator of 12 random numbers;

the frequency of the pulses at the output of the generator 9.

In order to check the efficiency of sensor 1, R-teeth extraction unit 2 and RR-intervals processing unit 3, an arrhythmic SI sequence composed of the patient's actual heart rate and impulses delayed relative to the heart's instinous rhythm must be supplied to the input of the latter. If the rhythm of the contractions of the patient's heart is sinus, it is sufficient to ensure in block 6 a delay, for example, an average delay time of 20 s and a variance of the delay time Oz of 0.0010 s. Thus, the delayed pulses mimic extrasystoles that do not fall into the middle of the RR-intervals and do not coincide with the R-teeth of the FORMER under examination. The resulting series of intervals between SIs such that the block 3 of processing the RR intervals reveals the presence of a test arrhythmia in accordance with expression (2).

If there are arrhythmias in the original ECS of the subject, the likely characteristics of the heart rhythm change. However, in the case of using these statistical characteristics of the delay time, the formation of test arrhythmias is still reliably ensured, since arrhythmias are characterized by combinations of normal, shortened and extended RR intervals, and their combination with random intervals forms an irregular rhythm. From the expression (3) it follows that the generator of 12 random numbers should form random numbers in accordance with the formula

P N - t;) - f.

(four)

where 1z is randomly distributed according to a normal law, with an average Shz value of 0.20 s and Oz variance of 0.0010 s. In order for the delay unit 6 to each time provide a new delay, it is necessary that the period of formation of random numbers n with the specified characteristics be less than the minimum possible period of the R-teeth and is, for example, 0.1 s. The delay time generated by the delay unit 6 may be constant, for example, less than half of the smallest possible heartbeat period.

In the process of analyzing the generated check rhythm, the RR interval processing unit 3 detects the presence of arrhythmia. Arrhythmia signals are indicated by a control indicator 5, confirming the health of the device. The display unit 4 is not functioning.

There is a likelihood of formation in the validation mode. rt.ma. This can occur if the delayed pulses coincide with the SI and if the delayed pulses hit the middle of the RR intervals with certain disturbances of the initial heart rhythm. So as

0

five

the delay and the true heart rate of the subject are constantly changing, by switching the device into a test mode for a longer time (for example, up to 5 s), you can reliably receive an abnormal heart rate at the input of the RR interval processing unit 3 and test the device's performance.

The activation of the test indicator 5 in the test mode indicates the correctness of the sensor 1, the R-teeth extraction unit 2 and the RR intervals processing unit 3. If at least one of these blocks is faulty, the test indicator 5 in the test mode does not work, which indicates the unreliability obtained by

5 device information. This also controls the correct use of sensor 1 (for example, the correct position of the electrodes, the treatment of the skin surface) and, consequently, the sufficiency of the amplitude and degree of noise immunity of the electronic cardiogram, which ensures the normal operation of the R-teeth extraction unit 2.

Thus, the device provides an increase in the reliability of detecting cardiac arrhythmias by promptly monitoring the operability of the main units of the device.

Claims (2)

1. A device for detecting cardiovascular arrhythmias, containing successively connected electrodio signal sensors and an R-teeth extraction unit, an RR interval processing unit, a display unit and a control indicator, characterized in that, in order to increase the reliability of the heart rhythm disturbances by control of R-teeth extraction and processing of RR-intervals, serially connected delay block and OR element are entered into it, the second input of which is connected to the output of the R-teeth extraction block, and the output - to the input of the RR-intervals processing block, and The switch, the first input of which is connected to the second input of the OR element, the second input - to the output of the RR-intervals processing unit, the first output - to the input of the delay unit, the second output - to the input of the display unit, and the third - to the control indicator. 2. The device according to claim 1, wherein the delay unit comprises a series-connected pulse generator, a first AND element and a pulse counter, the output of which (j is the output of the delay unit, the series-connected random number generator and the second element And, the output of which is connected to the second input of the pulse counter, and a trigger, the output of which is connected to the second input of the first element AND, the first input to the output of the pulse counter and the second input of the second element AND, and the second input is the input of the delay unit . five 0 five five 15 TI si O- K2 / -} I I 2 - I I yy I j d A-f / rj I  - a g 24 g 25 gpg -Ji-N f rIS Tlrn -v 7/7 I-; fS / ff 2 / Gi nineteen