JPH0571249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to an electrocardiographic abnormality detection device that can automatically detect abnormalities in an electrocardiogram.

(b) Prior art In general, a normal electrocardiogram is as shown in Figure 2.
It consists of each part of P, Q, R, S, and T. Therefore, if the electrocardiogram is observed in time sequence and a waveform as shown in Figure 3 is obtained, waveforms A and B are normal waveforms. However, waveform C is an abnormal waveform.

In recent years, electrocardiograms have been stored in time-sequential storage media such as magnetic tape, and after recording they can be processed and analyzed at high speed, or played back on a CRT screen to visually check for abnormalities. Electronic monitoring devices are emerging.

(C) Problems to be Solved by the Invention None of the above-mentioned conventional electrocardiogram monitoring devices can determine the presence or absence of an abnormality in real-time processing while observing the electrocardiogram. This was done using so-called batch processing after collecting a large amount of data. Therefore, even if an abnormality occurs, it cannot be reported in real time, and depending on the patient's symptoms, treatment may be delayed.

In view of the above, an object of the present invention is to provide an electrocardiogram abnormality detection device that can detect electrocardiogram abnormalities in real time.

(d) Means and operation for solving the problems As shown in FIG.
, an electrocardiographic waveform storage means 2 for updating and storing detected electrocardiographic waveforms in time sequence, and a plurality of storage areas 3 _-1 ,
..., 3 _-o , and the standard electrocardiographic waveform storage means 3 in which a plurality of standard electrocardiographic waveforms are stored, and the detected electrocardiographic waveform stored in the electrocardiographic waveform storage means 2 and the standard electrocardiographic waveform storage means 3. The similarity is determined by comparing each of the stored standard electrocardiogram waveforms, and if the detected electrocardiogram waveform is dissimilar to any of the standard electrocardiogram waveforms, the detected electrocardiogram waveform is stored as a new memory in the standard electrocardiogram waveform storage means 3. It is comprised of a comparing means 4 for storing in a region, and a counting means 5 provided corresponding to a plurality of standard electrocardiographic waveforms and counting the number of standard electrocardiographic waveforms determined to be similar by the comparing means for each standard electrocardiographic waveform.

This electrocardiographic abnormality detection device detects electrocardiographic waveforms, compares the detected electrocardiographic waveforms with multiple standard electrocardiographic waveforms in real time, and determines whether the detected electrocardiographic waveform is similar to any of the standard electrocardiographic waveforms. In this case, the detected electrocardiogram waveform is counted in the counting means corresponding to that standard electrocardiogram waveform, and if it is dissimilar to any standard electrocardiogram waveform, the detected electrocardiogram waveform is stored as a new standard electrocardiogram waveform. stored in the means.

(e) Examples The present invention will be explained in more detail below using examples.

FIG. 4 is a block diagram of an electrocardiographic abnormality detection device showing one embodiment of the present invention. In the same figure, 1
1a and 11b are biological electrodes for detecting electrocardiogram signals generated from the human body, and the electrocardiogram signals obtained from these biological electrodes 11a and 11b are added to a differential amplifier 13 via a high-pass filter 12. It is being The high-pass filter 12 is composed of a capacitor and a resistor, and is provided to remove fluctuations in the baseline unrelated to the electrocardiogram signal, that is, to remove low frequency components.

The differential amplifier 13 amplifies the electrocardiogram signal from which low frequency components have been removed, and inputs the amplified electrocardiogram signal to the A/D converter 15 via a low-pass filter 14. Normally, the electrocardiogram signal has a level of only about 1 mV, so if the input impedance of the device is small, it is easily affected by noise. Therefore, the input impedance of the differential amplifier 13 is set to be sufficiently large.

In accordance with the sampling theorem when performing A/D conversion, frequency components of 1/2 or more of the sampling frequency must be removed from the input of the A/D converter 15. In order to remove frequency components higher than 1/2 of this sampling frequency, the A/D converter 1
A low-pass filter 14 is provided on the input side of 5.

The sampling frequency of the A/D converter 15 is selected to be 200 Hz or more based on the sampling theorem since the frequency component of an electrocardiogram is approximately 100 Hz at most. Also, although 8-bit resolution is used, 12-bit resolution may also be used.

The electrocardiogram signal converted into a digital signal by the A/D converter 15 is sent to the CPU (microcomputer) 1.
Under the control of RAM 1, which is a semiconductor memory,
7 is stored. The electrocardiogram data storage area of this RAM 17 is configured in a ring-shaped endless loop. In addition to this, the RAM 17 has many storage areas which will be described later. It is a semiconductor memory
The ROM 18 stores an abnormality detection program, and the CPU 16 performs abnormality detection processing on the electrocardiogram waveform according to this program. When an abnormality is detected, a sound is emitted from the buzzer 20 via the buzzer interface 19. It is now possible to issue a warning. Further, if necessary, necessary information is outputted via the speech synthesis circuit 21 and the speaker 22.

Next, the abnormality detection processing operation of the above-mentioned embodiment device will be explained with reference to flowcharts shown in FIGS. 5 to 9.

The flowcharts in FIGS. 5 to 9 show the abnormality detection algorithm. In parallel with this abnormality detection process, the device executes a data import program, and the electrocardiogram data storage area of the RAM 17 is The latest electrocardiogram signal data is always stored.

When the operation of the apparatus starts, as shown in FIG. 5, first, parameters such as the end time of electrocardiogram monitoring are set [step ST (hereinafter abbreviated as ST) 1]. Then, another data import program is activated to start storing the electrocardiogram data xi in the storage area Xi of the RAM 17 (ST2).

Next, pass 1 and pass 2 processing (ST3, ST
Do 4).

Pass 1 is a routine for determining the difference value of the electrocardiogram data xi, and its specific processing procedure is shown in FIG. Pass 2 is a routine that finds the maximum difference value, and its specific processing steps are as follows:
It is shown in FIG.

When entering pass 1, HOB is stored in counter i as shown in FIG. 6 (ST31). Note that here, HOB indicates the head position of the data to be detected, and TOB, which will be described later, indicates the tail position of the data to be detected.

Next, in ST32, the difference value Δxi between the electrocardiogram data xi+1 specified by the counter i and xi is calculated, and this is stored in the RAM 17. Next, the counter i is incremented by +1 (ST33), and the value of the counter i is The process of calculating the difference value Δxi between the data at adjacent positions i+1 and i is repeated until the content becomes TOB (ST34). In ST34, when i=TOB,
This means that the difference value detection of the detection target interval has been completed,
Get out of path 1 and move on to path 2.

When pass 2 is entered, as shown in Figure 7, the
HOB is stored in the counter i, and the area of the RAM 17 that stores the maximum value Δx max of the difference value Δx is set to 0 (ST41). and the maximum value Δx max to be stored
and the difference value Δxi are compared in magnitude (ST42). If Δxi is larger as a result of the comparison, that Δxi is stored as the new maximum difference value Δx max (ST
43), if Δxi is not larger than the maximum value Δx max up to that point, ST43 is skipped and counter i is incremented by +1 (ST44), and i is TOB
The processes of ST42 to ST44 are repeated until reaching (ST45), and the maximum value Δx max of the difference values in the section from HOB to TOB is determined. As a result, the largest change in the target section is determined.

When the value of counter i reaches TOB, the determination of "i = TOB" in ST45 becomes YES, and then the value TL obtained by multiplying the obtained Δx max by 0.6, that is, 60% of the maximum value of the difference value, is Obtain (ST46). This will take you out of path 2. This TL is used as a trigger level for finding the electrocardiogram waveform, ie, QRS, and 0.6 is determined empirically, and may be set to other values as the case requires.

Again, return to the main routine in Figure 5 and pass 2.
Subsequently, in ST5, it is determined whether the set time has come.
This set time is for performing abnormality detection every set time, and here the set time is updated every second. In other words, the ST5 judgment is made every second.
YES, and then QRS detection processing is performed in ST6.

The QRS detection routine is as shown in Figure 8.
First, the value obtained by adding the offset value Os to HOB is i
Then, the counter j (the count value is the number of QRS detected in the target section) is set to 0 (ST61). Then, it is determined whether the difference value Δxi is greater than or equal to TL (ST62), and if the difference value Δxi is smaller than TL,
Assuming that QRS is not detected, add 1 to i (ST63), determine whether "i=TOB" (ST64),
If i is not TOB, it returns to ST62 and Δxi
ST62 until ≧TL or i=TOB
- Repeat the process of ST64.

When a difference value Δxi greater than TL appears, the judgment in ST62 becomes YES, which means that QRS is detected.
The point i is the QRS detection position, and the RAM 17
At the same time, the counter j is incremented by +1, ARP is added to i at that point, and the result is stored as a new i (ST65). Here, ARP takes into account the absolute refractory period, and since it does not contract even if a stimulus is applied during this period, QRS detection processing is skipped. Following ST55, it is determined whether “i≧TOB” (ST66), and if i is not TOB, the process returns to ST61, and again depending on the determination situation, ST61 to ST66
Process. If i=TOB,
When Δxi≧TL and the second QRS is detected,
The judgment in ST62 is YES, and i at that point is Yj=
(Y1) is stored as y1, j is incremented by +1 (j=2), and ARP is further added to i at that point.

As described above, the QRS position is stored in Yj.

Note that when i=TOB is determined in ST64,
The offset value Os is set to 0 (ST67), but ST
When i≧TOB is determined in 66, (i←i+ARP
(in some cases, i > TOB), the amount by which i exceeds TOB, i.e., i - TOB, is set as the offset value Os
(ST68).

When the QRS detection process is completed, in the main routine shown in FIG. 5, it is subsequently determined whether j=0 (ST7). If QRS is detected in this process, since j is not 0, the judgment in ST7 is NO.
Then, QRS classification processing is performed (ST8).
This QRS classification process is performed to classify which waveform the detected electrocardiographic waveform, ie, QRS, belongs to.

As shown in Figure 9, the QRS classification routine first sets template i' to 1 (ST81), compares the current input data (detected QRS) j and template i' (ST82), and determines whether they are similar. (ST
83). Template i' is a standard electrocardiogram waveform to be compared with the detected electrocardiogram waveform, and its waveform data is registered in the template storage area of the RAM 17. At the beginning of the operation, i'=0, but as the operation progresses, new electrocardiographic waveforms are detected and registered, so the template i' increases.

For input data j, if j=1, its waveform is
If j=2, the second detected electrocardiographic waveform will be compared with template i'.

Comparison of template i' and input data j is performed by determining the correlation coefficient of both waveforms. If the correlation coefficient is 0.9 or more, the two waveforms are determined to have a correlation and are similar; otherwise, they are determined to be dissimilar.

However, even if the electrocardiogram waveforms are the same, if the two waveforms are at different positions, the correlation coefficient will be 0.9 or less and they will be judged as dissimilar, so if a NO judgment is made in ST83, the contents of the counter k will be incremented by one step. Repeat until k reaches the predetermined value R+1 (ST85).
Perform similarity judgment in ST83. That is, the detected electrocardiographic waveform is shifted up to a maximum of R+1 with respect to template i', and a correlation coefficient is determined at each shifted position. If the highest value of the correlation coefficient is 0.9 or more during k=R+1 processing, both waveforms are said to be similar. Since the similarity is determined by relatively shifting both waveforms in this way, it is possible to perform a similarity determination with higher precision than when comparing only once.

If ST83 determines that both waveforms are similar,
The counter (counting the number of each template) corresponding to template i' is incremented by 1 and updated (ST86). Both waveforms are not similar, ST83
If the judgment is NO and the judgment of ST85 is YES,
i′ is incremented by +1 (ST85), and it is determined whether there are any more templates i′ to be compared (ST
88). If there are still templates to be compared, the judgment in ST88 becomes YES, the process returns to ST82, and the input data j and new template are
i′ is compared and it is determined whether they are similar or not (ST8
3. ST85), if both data are similar, add 1 to the counter corresponding to that template.
is performed (ST86), but since the two are not similar,
Furthermore, if there is no template to be compared (ST83, ST88), the input data j is registered as a new template (ST89). Then, the buzzer 20 is sounded (ST90). The sound of the buzzer 20 means the appearance of a new waveform, and if the already registered template is a normal waveform (standard waveform), the sound of the buzzer 20 indicates the detection of an abnormal waveform. .

After the QRS classification is completed, the main routine is ST
The process moves to step 9, where j=j-1 is processed, and the process returns to ST7. Then, a determination is made as to whether "j=0". If two or more QRSs are detected in the current QRS detection, since j=0 is not the case, classification processing is performed on the remaining QRSs until j=0.

If the judgment of “j=0” is YES in ST7,
Determine whether the end time has been reached (ST10), and unless it is the end time, return to ST5, perform QRS detection and QRS classification processing for the next 1 second,
Thereafter, the process continues until the end time is reached.

Through the above series of processing, time-sequential results are obtained.
QRS will be classified by similar waveforms. Once this classification has progressed to a certain extent, if a waveform that does not normally appear appears, it can be determined that this is an abnormal waveform.

Furthermore, in the case of a patient who has been evaluated several times, a normal waveform may be stored in advance in the ROM 18 as a template, and if a QRS that differs from this template appears, it may be considered abnormal.

(f) Effects of the Invention According to the electrocardiographic abnormality detection device of the present invention, the electrocardiographic abnormality detection device of the present invention monitors electrocardiographic waveforms in time sequence, sequentially compares the detected electrocardiographic waveforms with a plurality of standard waveforms, and detects when they are similar. , since the counting means corresponding to the standard waveform counts, it is possible to judge whether it is normal or abnormal based on the size of the counted value, and it is possible to detect abnormalities in real time.
Able to take prompt measures in case of sudden changes in patients. Furthermore, if the comparison results are dissimilar, the detected electrocardiogram waveform is stored as a new standard electrocardiogram waveform, so there is no need to determine the standard electrocardiogram waveform in advance, but rather due to individual differences. Even in such a case, by continuing the measurement, it is possible to accurately determine normality/abnormality, and there is an advantage that standard electrocardiogram waveforms of different shapes can be automatically stored.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of the electrocardiographic abnormality detection device of the present invention, FIG. 2 is a diagram showing a normal electrocardiographic waveform, and FIG. 3 is a diagram showing an example of an electrocardiographic waveform including an abnormal waveform. , FIG. 4 is a block diagram of an electrocardiographic abnormality detection device showing one embodiment of the present invention, and FIGS. 5 to 9
The figure is an operation flowchart of the concentric electromagnetic abnormality detection device, FIG. 5 is a flowchart showing the main routine, FIG. 6 is a flowchart showing details of pass 1 of the main routine, and FIG. 7 is a flowchart showing the main routine. Flowchart showing details of path 2 of
This figure is a flowchart showing details of the QRS detection routine of the main routine, and FIG. 9 is a flowchart showing details of the QRS classification routine of the main routine. 1: Electrocardiogram waveform detection means, 2: Electrocardiogram waveform storage means, 3: Standard electrocardiogram waveform storage means, 4: Comparison means.

Claims (1)

[Claims] 1. An electrocardiographic waveform detection means for detecting an electrocardiographic waveform, an electrocardiographic waveform storage means for updating and storing the detected electrocardiographic waveform in time sequence, and a plurality of electrocardiographic waveform storage areas, Standard electrocardiographic waveform storage means storing a plurality of standard electrocardiographic waveforms, each of the detected electrocardiographic waveforms stored in the electrocardiographic waveform storage means and the standard electrocardiographic waveforms stored in the standard electrocardiographic waveform storage means. comparing means for determining similarity by comparing the two standard electrocardiographic waveforms, and storing the detected electrocardiographic waveform in a new storage area of the standard electrocardiographic waveform storage means when the detected electrocardiographic waveform is dissimilar to any of the standard electrocardiographic waveforms; An electrocardiographic abnormality detection device comprising a counting means provided corresponding to a plurality of standard electrocardiographic waveforms and counting the number of similar electrocardiographic waveforms determined by the comparison means for each standard electrocardiographic waveform. 2. Claims in which the comparison means includes means for calculating a correlation coefficient between the detected electrocardiogram waveform and the standard electrocardiogram waveform, and the similarity is determined based on whether the correlation coefficient is greater than or equal to a predetermined value. The electrocardiographic abnormality detection device according to item 1.