JPH026529B2 - - Google Patents

Description

[Detailed Description of the Invention] (Object of the Invention) The present invention relates to a device used to analyze electrocardiograms continuously recorded over a long period of time for subjects who carry an electrocardiograph with them. It is an object of the present invention to provide a means for reducing the mental and physical constraints on a doctor when making a diagnosis using such a conventional device, and making it possible to quickly and accurately judge an electrocardiogram.

Conventionally, the Holter electrocardiograph has been well known as a portable long-term magnetic recording electrocardiograph, and is used for diagnosing angina pectoris and prescribing the amount of exercise in rehabilitation for heart disease. However, during the reproduction process for long-term magnetic recording that lasts for more than one day and night, the diagnostician cannot take his eyes off the waveform that is being reproduced. Furthermore, since this kind of electrocardiogram magnetic recording is performed while performing daily life, there are many artifacts mixed into the signal due to the movement of the human body or contact with objects. Since the true waveform and the waveform disturbed by artifacts have to be sorted out and judged, diagnosis is extremely difficult.

This invention was researched and developed in order to eliminate the drawbacks of the conventional analysis techniques for long-term electrocardiograms as described above, and the invention will be explained below with reference to the illustrated embodiments.

(Structure of the Invention) First, referring to FIG. 1, the device according to the present invention includes an electrocardiogram reproducing device 1, a heart rate measuring device 2, an ST deviation measuring device 3, and an extrasystole detecting device 4, which will be described below. , ST deviation sampling device 5, ventricular premature contraction sampling device 6, and time decoding device 7
and a multihead thermal recorder 8.

The electrocardiogram reproducing device 1 described above reproduces and outputs an electrocardiogram recorded on a magnetic recording element such as a magnetic tape of a Holter electrocardiograph and recording time signals at fixed time intervals during the recording as voltage signals, respectively. The recorded time is reproduced and output at a speed several tens of times faster than when it was recorded. In the illustrated example, the playback speed is 60 times the recording speed, so 26 hours of recording by the Holter electrocardiograph is played back in 26 minutes. Further, the magnetic recording element in the example described here is a magnetic tape, and the clock signal is recorded every minute by the magnetic recording device, but according to the present invention, the reproduction speed can be increased. The intervals between the clock signals are not limited to the values listed here.

Hereinafter, with reference to FIG. 3, the heart rate measuring device 2 of the present invention converts the RR interval into the number of heartbeats per minute (digital value) using a pulse generation circuit and a counter, and then performs D/A conversion to convert it into an analog voltage. It has a circuit that outputs the value at regular intervals such as every minute.

Next, ST deviation measuring device 3 in this invention
The output value at a point (t ₀ ) selected at an appropriate position between the P wave before the R wave and this R wave is set to zero level, and the baseline passing through that zero level and the point after the R wave are
The potential difference (ST level) with a sampling point selected at an appropriate position between the STs is output at regular intervals.

What is shown in FIG. 4 is an example of the above-mentioned ST deviation measuring device 3, in which the amplified electrocardiogram reproduction output is selected by the zero level setting circuit as described above, and the ST The level value is measured. The output of this measurement passes through a smoothing circuit and is input to the multihead thermal recorder 8 as an analog output, while also passing through a judgment circuit that determines the presence or absence of ST deviation, and then being sent to the ST deviation sampling device 5 via the control circuit 9. input. However, this determination circuit determines that there is ST deviation if the ST level is equal to or higher than a predetermined constant value (±0.2 mV).

The above-described premature contraction detection device 4 detects the frequency of ventricular premature contractions and the frequency of supraventricular premature contractions, which are premature contractions other than ventricular premature contractions, such as atrial and sinus contractions. It is a device. That is, this device has a circuit that receives the above-mentioned electrocardiogram reproduction output and measures the QRS width and RR interval as shown in Figure 3, and continuously applies a voltage corresponding to this RR interval for a certain period of time at certain short intervals. and output it. However, the reason for outputting here is that the RR interval is not normal, and the predetermined allowable ratio (usually
It will be output only if the length is shorter than 30% (which is considered normal). At the time of this output, the output is performed at different voltage levels classified depending on whether the QRS width is wider than 120 milliseconds, which is accepted as the standard.

Here, when the QRS width is wider than 120 ms,
An abnormality in the RR interval corresponds to a premature ventricular contraction, and an abnormality of less than 120 milliseconds corresponds to a premature supraventricular contraction.

A specific example of the above-mentioned extrasystole detection device 4 is shown in FIG. That is, the electrocardiogram reproduction output that has passed through the amplifier circuit and is input to the RR interval measuring circuit is used to measure the RR interval by measuring the absolute time of the peak of one R wave and the next R wave, in this RR interval measuring circuit.
The measurement output is input to the determination output circuit.

On the other hand, the electrocardiogram reproduction output signal is similarly input to the QRS detection circuit and the delay circuit, but the QRS detection circuit is connected to a point (t ₂ ) (R
Detect the R wave at a position higher than the peak of the wave height of the P wave so as not to detect the wave, measure the absolute time of the position of the point (t ₂ ), and also set the position at an appropriate point in the middle of the S wave. An S wave is detected at point (t ₃ ) and the absolute time at the position of point (t ₂ ) is measured. Further, the delay circuit described above delays the input electrocardiogram waveform by a predetermined time and outputs the delayed signal. The time constant of the delay circuit is selected in accordance with the time difference between the absolute time of the starting point (t ₁ ) of the Q wave and the absolute time of the point (t ₂ ) determined empirically from a number of experiments.
The QRS width measurement circuit is a circuit that receives the outputs of the QRS detection circuit and delay circuit and compares these outputs.
Through this comparison, the absolute time of the Q-wave starting point (t ₁ ) is determined by estimation based on the time constant of the delay circuit. The QRS detection circuit measures _the absolute time of the point (t ₂ ) as described above, and also measures the absolute time of the S wave at the point (t ₃ ) mentioned above. Since _the point (t _{3 ) can be set so that the time difference with the wave end point (t 4} ) is approximately the same as the delay time of the delay circuit, the absolute time of the point (t ₃ ) can be measured. By this, the absolute time of the point (t ₄ ), which is the end of the S wave, can be determined. Therefore, the QRS width measuring circuit measures the absolute time of the point (t ₂ ) and the point (t ₃ ), thereby determining the point (t ₁ ).
The QRS width, which is the interval between points (t ₄ ), is converted into voltage and output. In this way, the QRS width voltage signal output from the QRS width measurement circuit is input to the determination output circuit.

In this way, the RR interval measurement circuit and QRS
The outputs of the width measurement circuits are respectively input to determination output circuits.

Although illustration of this judgment output circuit is omitted to avoid complication, it consists of a switch circuit as shown below and an output distribution circuit that receives the output of the switch circuit as input, and the output of this output distribution circuit is the judgment output. It is designed to be input to a multihead thermal recorder 8 as the output of the circuit.

The switch circuit receives input from the RR interval measuring circuit, and determines every minute whether the RR interval, which is the input, is shorter than the above-mentioned allowable rate,
If it is shorter than the allowable rate, the input from the RR interval measuring circuit at the time of this determination is output continuously for one minute.

The output distribution circuit receives the input from the switch circuit and determines the magnitude of the QRS width and 120 milliseconds,
When the QRS width is smaller than 120 milliseconds, a constant high DC voltage value is output, and when it is large, a constant low DC voltage value is superimposed on the output of the switch circuit and output, and the output is input to the multihead thermal recorder 8. By doing this, the histogram of supraventricular premature contractions is recorded above the baseline set at a certain level on the recording paper, and the histogram of ventricular premature contractions is recorded below the baseline (second (see figure).

Next, the ST deviation sampling device 5 of the present invention receives the above-mentioned electrocardiogram reproduction output and extracts one frame between time displays (hereinafter referred to as "time frame") displayed on the recording paper by the output of the time decoding device 7, which will be described later. outputs a voltage signal applied to an electrocardiogram waveform corresponding to one heartbeat occurring at However, in this case, if this electrocardiogram waveform includes a wave with an ST deviation, the electrocardiogram waveform corresponding to one heartbeat with that ST deviation is selected as a sample, and the signal related to that waveform is The image is enlarged and output.

What is shown in FIG. 6 is a specific example of such an ST deviation sampling device 5. In this example, the sampling circuit receives the electrocardiogram reproduction output through the amplifier circuit, receives the output of the ST deviation determination circuit (see FIG. 4) in the ST deviation measuring device 3 via the control circuit 9, and receives the second The waveform output for one heartbeat sampled from the electrocardiogram playback output within the time frame (10 minutes) between time displays in the figure is stored in memory, and then output at the next time frame. .

That is, the sampling circuit, together with the following sampling time control circuit that receives the electrocardiogram reproduction output, compresses 10 minutes into the time of one heartbeat.
In other words, a time axis compression circuit and an A/D conversion circuit that stretch one heartbeat into 10 minutes on the time axis and output the result (however, these sampling time control circuits, time axis compression circuits included in the sampling circuit,
An A/D conversion circuit is not shown. ), and the digital signal output supplied from the sampling time control circuit via the time base compression circuit and the A/D conversion circuit is supplied to the memory circuit or. The sampling time control circuit described above samples and outputs the first waveform that appears here if there is one or more waveforms with ST deviation during the first 9 minutes and 52.5 seconds in the time frame (10 minutes) described above. do. However, as described above, when the potential value (ST level) at the ST deviation sampling point (see Figure 3) is ±0.2 mV or more, it is determined that there is an ST deviation. As described above, the signal indicating the presence or absence of ST deviation is supplied from the ST deviation measuring device 3 through the control circuit 9. In the electrocardiogram reproduction output input to the sampling circuit, if there is no waveform related to the ST deviation during the 9 minutes and 52.5 seconds, the electrocardiogram waveform of one heartbeat occurring in the next 5 seconds is sampled and output. In this case, it does not matter whether the waveform includes ST deviation or not. In other words, if there is even one waveform with an ST deviation in the first 9 minutes 57.5 seconds of this time frame, that waveform with an ST deviation will also become an ST deviation.
If there is no waveform with deviation, a normal waveform without ST deviation is stored in the memory circuit or. Thus, the waveform stored in the memory circuit for 9 minutes 52.5 seconds + 5 seconds = 9 minutes 57.5 seconds will be converted into an analog signal through the output circuit with the D/A conversion circuit at the end of that time frame, that is, at the next time frame. The memory circuit,
The one that is in operation is held during its output time, and its output waveform is displayed on the paper surface corresponding to the time frame during memory operation (hereinafter referred to as "paper frame").
will be recorded.

If there is no heartbeat during the 5 seconds mentioned above, the waveform of the heartbeat in the first 0.8 seconds of the remaining 2.5 seconds of that time frame is stored in the memory circuit or in the next time frame. , the waveform voltage corresponding to that memory is output. In other words, according to this example, the paper frame corresponding to one time frame may sometimes record a sampling of the electrocardiogram waveform that occurred in the previous time frame, and also the last frame of one time frame. Electrocardiogram waveforms for heartbeats that occur during 1.7 seconds will be excluded as sampling. In this example, the sampling exclusion period, which is 1.7 seconds, is of course better if it is shorter, but the electrical circuit from the input of the electrocardiogram waveform output from the electrocardiogram reproduction device 1 to the completion of recording by the multihead thermal recorder 8 described below. This example was designed as described above, taking into account the time required due to the characteristics of. However, such a design is irrelevant to the gist of the present invention, and by adopting an electrical circuit design that can operate more quickly, the above-mentioned exclusion period can be practically eliminated. In this example, 0.8 seconds starting from 0.3 seconds before R is used as the time for one heartbeat.

In this example, the sampling circuit is supplied with the output supplied from the sampling time control circuit through the time base compression circuit and A/D conversion circuit, which is alternately switched to the memory circuit every 10 minutes. Contains an output switching circuit for This means that, for example, a waveform signal stored in the memory circuit at a certain time frame (10 minutes) is supplied to the output circuit at the next time frame, so the output of the sampling circuit at the next time frame is sent to the memory circuit. This is because it needs to be memorized.

Next, the premature ventricular contraction sampling device 6 of the present invention receives the electrocardiogram reproduction output, and sequentially samples a waveform of a premature ventricular contraction when it is included in each time frame described above. Then, in each time frame, the waveforms sampled as described above are enlarged to each of the allocation widths in which a small number of waveforms are allocated to a fixed time width, and the waveforms are sequentially output in the number of waveforms that are allocated.

FIG. 7 shows a specific example of the premature ventricular contraction sampling device 6 according to the present invention. As can be seen from the diagram, this specific example device has the same overall block configuration as the ST deviation sampling device 5 shown in FIG. 6, and the sampling circuit similarly includes a sampling time control circuit and a time axis compression circuit. , an A/D conversion circuit, and an output switching circuit. However, the sampling time control circuit in this specific example is as follows.

That is, the sampling time control circuit receives the electrocardiogram reproduction output and opens the sampling gate for 5 milliseconds every 5 milliseconds, and if there is premature ventricular contraction during the period when this gate is open, the R wave of the heartbeat at that time is detected. By continuing to open the gate for 0.64 seconds starting 0.3 seconds before the ventricular premature contraction, the waveform of 0.64 seconds is divided into the above time frames (10 minutes) by passing the output of the wave related to the premature ventricular contraction through a time axis compression circuit. Expand and output to the specified allocation width. In this case, the allocation width is 1/4 (2.5 minutes) when selecting 4 samples to be recorded on the recording paper in each time frame, and 1/8 (0.25 minutes) when selecting 8 samples. ). here,
A signal regarding the presence or absence of premature ventricular contraction is input from the determination output circuit of the premature contraction detection device 4 (FIG. 5) through the control circuit 9 to the sampling time control circuit of the sampling circuit.

In this way, the output of the wave related to premature ventricular contraction through the time axis compression circuit is transferred to the A/D conversion circuit.
And after being stored in a memory circuit or through an output switching circuit similar to the output switching circuit in the ST deviation sampling device 5 described above,
At the next time frame, the signal is D/A converted by the output circuit, input to the multihead thermal recorder 8, and recorded on the running thermal recording paper.

The premature ventricular contraction sampling record shown in Figure 2 is made by setting the recording paper length corresponding to the 10-minute time frame to 22 mm, and by providing a 2 mm blank space between adjacent time frames. This is an example in which four sampling records are assigned to.

Next, the time decoding device 7 in this invention is
A circuit that receives the electrocardiogram reproduction output described above and outputs signals corresponding to the beginning and end time digits of each time frame at a preset constant time interval based on the time signal at constant intervals included in the reproduction output. According to one specific example, 10 minutes is set as the time frame.

Finally, the multihead thermal recorder 8 according to the present invention includes a plurality of parallel thermal heads and a thermal recording paper running device, and includes the above-described heart rate measuring device 2, ST deviation measuring device 3, extra contraction detecting device 4, The outputs of the ST deviation sampling device 5, ventricular extrasystole sampling device 6, and time decoding device 7 are input to separate thermal heads, but as a specific example,
The running speed of the thermal recording paper was set to 2.5 cm/sec.

In addition, in FIG. 1, 9 is a control device for controlling the operation of each device indicated by reference numerals 2 to 8.
Further, in the illustrated example, by switching the input terminals of the CRT 12, a static display of the electrocardiogram can be displayed on the CRT 12 through the memory device 10, and a superimposed display can be displayed on the CRT 12 through the superimposed display device 11. 1 channel recorder 13
is provided so that by switching the input terminal, it is possible to take out a hard copy of the electrocardiogram or the heart rate trend record and time record described later, and 14 is a large time display with a digital display. It is an indicator.

The configuration of the present invention has been described above with reference to embodiments, and the present invention includes the electrocardiogram reproducing device 1, heart rate measuring device 2, ST deviation measuring device 3, premature contraction detecting device 4, and ST a deviation sampling device 5, a premature ventricular contraction sampling device 6,
It has a time decoding device 7 and a multi-head thermal recorder 8, of which the outputs of each of the devices indicated by numerals 2 to 7 are respectively input to different thermal heads of the multi-head thermal recorder 8. The thermal recording paper running in the multihead thermal recorder 8 shows the heart rate, ST level, supraventricular, and ventricular phases of a subject who carries an electrocardiograph with him or her, as shown in Figure 2. Records of external contractions, sampling records of ST deviation, and sampling records of premature ventricular contractions are displayed in parallel along the time axis. At that time, the heart rate, ST level, and extrasystoles are each recorded at short intervals, such as one minute. In particular, as described above, the extrasystole detection device 4
The QRS width and RR interval are measured, and the signal value of the RR interval that is shorter than the allowable rate is output continuously for a certain period of time at certain short intervals, so the magnitude of extrasystole is continuously recorded as a histogram on the recording paper. On the other hand, the signal values that are the cause of this histogram are classified depending on whether the QRS width is wider than 120 milliseconds, and these divided signal values are output at different potential levels. 2
As illustrated in the figure, the histograms for supraventricular extrasystole and ventricular extrasystole are clearly displayed separately in the same channel on the recording paper. Trends in premature contractions, such as the frequency and strength of each contraction, can be clearly understood at a glance.

Further, according to the present invention, as described above, ST
There is an deviation sampling device 5, which detects the ST deviation when an electrocardiogram waveform with an ST deviation is included in each time frame, which is the time interval displayed on the recording paper by the output of the time decoding device 7. A waveform sample corresponding to one heartbeat is selected, and the waveform for one heartbeat is expanded to that time frame width and output.

Further, according to the present invention, there is the above-mentioned premature ventricular contraction sampling device 6, which sequentially samples the wave of premature ventricular contraction when the wave of premature ventricular contraction is included in each time frame, and In each time frame, the sampled waves are enlarged to each allocation width in which a small number of waves are allocated to a certain time width, and sequentially output by the allocated number.

In this way, the ST deviation sampling device 5
The output signals of the ventricular extrasystole sampling device 6 and the output signals of the ventricular extrasystole sampling device 6 are input to a multi-head thermal recorder, and these output signals are paralleled in separate channels and recorded on paper frames of the recording paper corresponding to the time frames. Continuously recorded.

(Effects of the Invention) Up to now, the structure and embodiments of the present invention, as well as the effects of the present invention, have been described in detail. While the heart rate and ST level of a living subject are clearly recorded on the recording paper as a continuous wave-like display over time, as illustrated in Figure 2, premature ventricular contractions and supraventricular contractions The frequency and intensity of premature contractions are displayed separately in one channel, while in another parallel channel, a sample of the ECG waveform within a heartbeat with ST deviation is displayed over an appropriately set period such as 10 minutes. Each time frame is displayed as a sample, and in other parallel channels, there are a small number of sample waveforms of premature ventricular contractions that occurred at the same time frame in the paper frame corresponding to the paper frame in the ST deviation sampling record described above. Multiple items are displayed. Therefore, when diagnosing the presence or absence of a lesion or its condition from the records of heart rate, ST level, and extrasystoles described above, it is necessary to check the heart rate, ST level, and premature contraction while referring to the waveforms of each sampling record. By observing the trend of extrasystole, it is possible to immediately judge the degree of reliability of the recording of heart rate, ST level, and extrasystole on the chart paper. In other words, as mentioned above, a particular problem in the analysis of long-term electrocardiogram recordings is the extremely frequent inclusion of artifacts, which can cause errors in judgment with conventional analysis methods, so it is difficult to ensure sufficient diagnostic reliability. However, according to the present invention, abnormalities in heart rate, ST level, or premature contraction trends can be observed by referring to sampling waveforms of ST deviation and ventricular premature contraction. Therefore, it becomes very easy to determine whether or not artifacts have been mixed in at those abnormal locations. In other words, if you refer to Figure 2, it is easy to see that such an abnormal location is due to disturbances or defects in the sample waveform at the locations indicated by * and arrow marks, and that artifacts were introduced at approximately this time. can be determined, therefore,
Even if there is an abnormality in the heart rate or other recorded trend at a time that approximately corresponds to this, the abnormality at that time can be excluded and diagnosed. In addition, by presetting the time corresponding to the abnormal point in the trend, feeding the recording paper at high speed and stopping at that time, the electrocardiogram is slowly played back at the original recording speed, so that the type of arrhythmia can be determined. It is easy to check the degree.

According to the present invention, long-term electrocardiogram recordings are played back in an extremely short time (according to the embodiment, 26 hours of recordings take 26 minutes), and it is necessary to continue monitoring the recordings during the processing. Moreover, the heat-sensitive recording paper obtained by this device is 15
If folded in a zigzag pattern every cm, it will last for 26 hours.
It is extremely convenient for re-examination as it provides a light and thin record that can be stored in just 12 pages.

Therefore, the present invention greatly contributes to the accurate and efficient analysis of long-term electrocardiograms and relieves the doctors involved in the analysis of the electrocardiograms from mental and physical pain.

[Brief explanation of drawings]

FIG. 1 is a basic block diagram of an embodiment of a long-term electrocardiogram analysis device according to the present invention, FIG. 2 is an example of an electrocardiogram analysis record according to an embodiment of the present invention, and FIG.
The figure is a schematic diagram showing the electrocardiogram part, FIG. 4 is a block diagram of the ST deviation measuring device 3 in one embodiment of the present invention, FIG. 5 is a block diagram of the premature contraction detecting device 4, and FIG. Similarly, FIG. 7 is a block diagram of the ST deviation sampling device, and FIG. 7 is a block diagram of the ventricular premature contraction sampling device. 1 is an electrocardiogram reproducing device, 2 is a heart rate measuring device, and 3 is an electrocardiogram reproducing device.
ST deviation measuring device, 4 is extrasystole detection device 4, 5
is an ST deviation sampling device, 6 is a ventricular premature contraction sampling device, 7 is a time decoding device, 8 is a multi-head thermal recorder, 9 is a control device,
10 is a memory device, 11 is a superimposed display device, 12
is CRT, 13 is 1 channel recorder, 14
is a time indicator.

Claims (1)

[Scope of Claims] 1. An electrocardiogram reproducing device 1 that reproduces and outputs an electrocardiogram recorded on a magnetic recording element and recording time signals at regular intervals as respective voltage signals at a speed several tens of times faster than recording; and an electrocardiogram reproducing device 1. A heart rate meter measurement device 2 that receives the electrocardiogram playback output, converts the RR interval into heart rate per minute using a pulse generation circuit and a counter, and outputs it as an analog signal at fixed short intervals.
Then, upon receiving the electrocardiogram reproduction output, set the output value at a point appropriately selected between the P wave before the R wave and this R wave as a zero level, and set the output value between the base line passing through that zero level and the ST after the R wave. an ST deviation measuring device 3 that outputs a potential difference (ST level) with a sampling point set at an appropriate position of the body at regular intervals;
If the RR interval is shorter than a predetermined permissible percentage, the voltage applied to said measurement of the RR interval at different potential levels differentiated by whether the QRS width is wider than 120 ms. Between an extrasystole detection device 4 that continuously outputs values at regular intervals for a certain period of time, and a time display that receives the electrocardiogram reproduction output and is displayed on the recording paper by the output of the time decoding device 7 described below. When an electrocardiogram waveform corresponding to one heartbeat occurring in each time frame that is one frame includes a waveform with an ST deviation, the electrocardiogram waveform corresponding to that one heartbeat is sampled, and the signal related to that waveform is used for the time frame. ST to be expanded and output to a time width of
A deflection sampling device 5 receives the electrocardiogram reproduction output described above, sequentially samples the waveform of premature ventricular contraction in each time frame when the waveform of the premature ventricular contraction is included, and divides each time frame into a small number in a certain time width. a ventricular premature contraction sampling device 6 which enlarges the sampled waveform to each assigned width and sequentially outputs the sampled waveform by the assigned number; a time decoding device 7 that outputs a signal corresponding to the time digits at the beginning and end of each time frame at a predetermined time interval based on the time signal, and a plurality of parallel thermal heads and heat-sensitive recording paper. The above-mentioned heart rate measuring device 2, ST deviation measuring device 3, extra-systole detecting device 4,
A long-term electrocardiogram comprising a multihead thermal recorder 8 in which the outputs of the ST deviation sampling device 5, the ventricular extrasystole sampling device 6, and the time decoding device 7 are input to separate thermal heads. Analysis device.