JP2003000561A - R wave recognition method, RR interval measuring method, heart rate measuring method, RR interval measuring device, and heart rate measuring device - Google Patents

Abstract

(57) [Summary] [Problem] To prevent erroneous detection of a peak value due to body movement and detect an R wave accurately and almost in real time. SOLUTION: In step S1, an initial amplitude value A (0) of ECG data is read and set as a temporary maximum value MAX. In step S2, n = n + 1. In step S3, the next amplitude value A (1) of the ECG data is read, and it is determined whether MAX-A (1)> 0.
If No, A (1) is set to the temporary maximum value MA in step S4.
Set X, and return to step S2. In step S3, Y
If es, MAX-A (n) in step S5
It is determined whether or not> L1. If No, the process proceeds to step S2, where the next amplitude value A (2) of the ECG data is read, and the calculation in step S3 is performed. If Yes in step S5, the process proceeds to step S6, where the maximum value MAX is set.
Is determined as the peak of the R wave.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ECG (electrocardiograph).
R wave recognition method for recognizing R wave for the purpose of measuring RR interval and heart rate from waveform, and further RR interval measuring method and device based on this R wave recognition method, heart rate measurement The present invention relates to a method and an apparatus.

[0002]

2. Description of the Related Art Conventionally, as a method for detecting a heartbeat from an ECG waveform, there has been disclosed "ECG
"A method and apparatus for detecting a heartbeat from a waveform" are known, and as a method for calculating a heart rate, Japanese Patent Laid-Open No. 9-17312
"Method and apparatus for calculating heart rate from ECG waveform" of Japanese Patent Publication is known.

[0003]

However, in the above-mentioned conventional example, the erroneous detection of the R wave due to the body movement is not described. When a subject moves the body during ECG waveform measurement, so-called body movement occurs, the ECG waveform drifts, and the maximum value of the amplitude of the ECG waveform rises or the minimum value falls compared to when the body movement does not occur. The phenomenon occurs.
The above-mentioned JP-A-9-168521 and JP-A-9-17.
As described in Japanese Patent No. 3312, in a method of recognizing a local maximum value found above the number of average peak values, for example, a threshold of 40%, as an R wave, for example, an ECG waveform shown in FIG. In this case, there is an R wave that cannot be detected by the threshold value A, or a local maximum value that is not the R wave is detected by the threshold value B, and eventually even if the threshold value is changed, it is impossible to recognize all R waves. Is. Further, the R wave cannot be recognized in real time by such a method.

By passing the ECG waveform through a filter, low-frequency components generated by body movement are removed,
There is also a method to reduce the variation in the peak value, but the frequency band to be removed changes depending on the subject and the body movement of the subject, and it is necessary to reset the frequency band to be removed each time, which is troublesome. There are drawbacks.

In general, the drift of the ECG waveform due to body movement is 1
The cycle is about several seconds. On the other hand, the time distance from the R wave peak occurrence to the S wave peak occurrence is 50 to 1
Sufficiently short, about 50 msec. Therefore, as is clear from FIG. 4, when the R wave rises, the S wave also rises by about the same amount, and when the R wave falls, the S wave also falls by about the same amount. That is, even if the ECG waveform drifts due to body movement, the variation amount of the difference D between the amplitudes of the R wave peak and the S wave peak is extremely smaller than the variation amount of the absolute value of the R wave amplitude. Also,
Generally, the difference in amplitude between the R wave peak and the S wave peak is very large compared to the difference in amplitude between the local peaks of the other continuous peaks and valleys.

An object of the present invention is to realize an R-wave recognition method for avoiding erroneous detection of a peak value due to body movement and detecting an R-wave accurately and almost in real time, and further based on this R-wave recognition method. An RR interval measuring method and apparatus, and a heart rate measuring method and apparatus are provided.

[0007]

The R-wave recognition method according to the present invention for achieving the above-mentioned object is an R-R from an ECG waveform.
In the R-wave recognition method for recognizing R-waves for measuring intervals and heart rates, a first step of detecting a local peak value of a mountain of the ECG waveform and storing the temporal position and amplitude thereof, The second step of calculating the difference between the local peak value of the peak of the ECG waveform and the amplitude value of the ECG data thereafter, and if the difference between the amplitude values obtained in the second step is larger than a predetermined threshold value. , A third step of recognizing a local peak value of a peak of the ECG waveform as a peak of an R wave, and a fourth step of sequentially repeating the first to third steps until the end of the ECG waveform. It is characterized by

RR interval measuring method and ECG according to the present invention
In an RR interval measuring method for measuring an RR interval from a waveform, a local peak value of a peak of the ECG waveform is detected,
The first step of storing the temporal position and the amplitude, the local peak value of the peak of the ECG waveform, and the subsequent ECG
If the difference between the amplitude values obtained in the second step and the second step of calculating the difference between the amplitude values of the data is larger than a predetermined threshold value, the local peak value of the peak of the ECG waveform is set to R.
A third step of recognizing a peak of a wave, a fourth step of sequentially repeating the first to third steps until the end of the ECG waveform, and a difference in temporal position of the R wave are sequentially calculated. And a fifth step of setting an R-R interval.

In the heart rate measuring method and the heart rate measuring method for measuring a heart rate from an ECG waveform according to the present invention, the E
The first step of detecting the local peak value of the peak of the CG waveform and storing the temporal position and amplitude thereof, and calculating the difference between the local peak value of the peak of the ECG waveform and the amplitude value of ECG data thereafter. If the difference between the amplitude value obtained in the second step and the amplitude value obtained in the second step is larger than a predetermined threshold, the local peak value of the peak of the ECG waveform is recognized as the peak of the R wave, and the R wave is recognized. And a fourth step of sequentially calculating the heart rate by repeating the first to third steps until the end of the ECG waveform.

The RR interval measuring apparatus according to the present invention is an EC
In an R-R interval measuring device for measuring an R-R interval from a G waveform, a local peak value of a peak of the ECG waveform is detected, and a local peak value of a peak of the ECG waveform and an ECG measured thereafter. If the difference from the amplitude value of the waveform is larger than a predetermined threshold value, the step of recognizing the local peak value of the peak of the ECG waveform as the peak of the R wave and storing the time position of the R wave is sequentially performed. Repeat R until the end of ECG waveform
R wave recognition means for recognizing the wave and RR interval calculation means for sequentially calculating the RR interval from the temporal positions of the plurality of R waves are provided.

A heart rate measuring apparatus according to the present invention is a heart rate measuring apparatus for measuring a heart rate from an ECG waveform, which detects a local peak value of a mountain of the ECG waveform to obtain the ECG waveform.
Local peak value of peak of waveform and EC measured thereafter
If the difference from the amplitude value of the G waveform is larger than a predetermined threshold value,
A step of recognizing the local peak value of the peak of the ECG waveform as a peak of the R wave and sequentially storing the number of times of the R wave generation until the end of the ECG waveform, and a heart rate calculating means for calculating a heart rate. It is characterized by being provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail based on the embodiments shown in FIGS. FIG. 1 is a block diagram illustrating the first embodiment. The cardiac potential electrode 1 is connected to a biological amplifier 2 that amplifies a biological signal input from these electrodes. The biological amplifier 2 is connected to the A / D converter 3, and further connected to the arithmetic unit 4 including a CPU, a memory and the like. The arithmetic unit 4 is connected via an I / F unit 5 to a display device 6, a command input device 7 for inputting commands including a keyboard and a mouse, and a recording device 8 such as a hard disk.

The cardiac potential input from the cardiac potential electrode 1 attached to the subject is input as a relative potential with 0 V at an arbitrary point, amplified by the living body amplifier 2, and then A / D.
It is converted into a digital signal by the converter 3 and sent to the arithmetic unit 4 as a digital signal.

The operator informs the subject that the preliminary measurement is to be started, and a predetermined time (for example, if the heartbeat is not enough) is calculated for calculating the average value of the difference between the amplitudes of the tentative R wave peak and the S wave peak. Time to occur about 20 times, if RR interval is 800m
If it is assumed to be 16 seconds, it will be 16 seconds). When the operator inputs a command to start the measurement from the command input device 7 with a mouse or the like, the arithmetic unit 4 sends a signal instructing the ECG waveform to be taken into the memory for the predetermined time described above, and then the temporary operation is performed. The calculation for calculating the difference R0 between the amplitudes of the R wave peak and the S wave peak is performed.

The calculation unit 4 finds the maximum value Amax and the minimum value Amin of the amplitude for the captured ECG waveform, sets X as a constant of about 0.6 to 0.8, and sets X · Amax to the peak detection of the peak. , And X · Amin are used as thresholds for peak detection of the valley, and the search is sequentially started from the measurement data at the start of measurement.

The calculation unit 4 first starts the search for a mountain peak. Then, when a local maximum value larger than X · Amax is detected, this is taken as the amplitude value of the peak of the R wave. Then, the calculation unit 4 starts searching for the peak value of the valley. Then, the local minimum value smaller than the threshold value X · Amin is recognized as the amplitude value of the S wave peak, and the difference between the amplitudes of the R wave peak and the S wave peak is calculated and stored in the memory. The calculation unit 4 starts searching for the peak of the mountain again, sequentially calculates the difference in amplitude between the R wave peak and the S wave peak, further calculates the average value of these, and uses this as the temporary R wave peak. And the average value R0 of the difference in the amplitude of the S wave peak.

Next, the operator informs the subject that the main measurement will be performed, and inputs a command from the command input device 7 to start the measurement of the ECG waveform. The calculation unit 4 receives the average value R of the difference between the amplitudes of the tentative R wave peak and the S wave peak from the memory.
Call 0 and set the number, for example 70%, of the R wave and S
The threshold L1 for wave detection is set. Then, the calculation unit 4
Recording device 8 while capturing the CG waveform and storing it in memory
Also record the data. Further, the threshold value L1 is not limited to this, and for example, the average value R0 of the difference between the amplitudes of the tentative R-wave peak and the S-wave peak is calculated manually after the preliminary experiment described above, and the number of the values is calculated. Of course, it may be set to 70%, for example.

FIG. 2 is a flow chart of the first embodiment, where the amplitude value of the ECG data is A (n), n = 0. In step S1, the calculation unit 4 reads the first amplitude value A (0) of the ECG data, and determines the temporary maximum value MAX.
And Then, n = n + 1 is set in step S2, and the next amplitude value A of the ECG data is set in step S3.
(1) is read and it is determined whether MAX-A (1)> 0. If No, the process proceeds to step S4 and A
(1) is set to the temporary maximum value MAX, and the process returns to step S2.

Then, if Yes in step S3, the process proceeds to step S5, and MAX-A
It is determined whether (n)> L1. If No, the process proceeds to step S2, n = n + 1, the next amplitude value A (2) of the ECG data is read, and the process proceeds to step S3 to perform the above-described calculation.

If Yes in step S5, the process proceeds to step S6, and the maximum value MAX is determined to be the peak of the R wave. Then, the calculation unit 4 stores the time of the maximum value MAX in the memory as the peak time T1 of the first R wave and the heart rate M = 1.

In many cases, the MAX wave is generated before the S wave is generated.
It is possible to set the threshold value L1 so that −A (n)> L1, but if MAX-A (n)> L1 is satisfied even when the peak of the S wave occurs, it is generally The peak of the R wave can be recognized 50 to 150 msec after the generation of the R wave, and the peak of the R wave can be recognized almost in real time according to this algorithm.

Such calculation is sequentially repeated, and the peak time T2 of the second R wave, ..., And the peak time TM of the Mth R wave are recorded in the recording device 8, and the heart rate M is calculated each time.
Is called from the memory, 1 is added, and the heart rate is re-stored in the memory. Further, the RR interval is calculated from the peak time of the R wave and displayed on the display device 6. Obviously, if the peak of the R wave can be recognized, the RR interval and the heart rate can be calculated instantaneously, and in the end, the heart rate and the RR interval can be calculated and displayed in almost real time.

To stop recording, the operator inputs a command from the command input device 7. Upon receiving the command, the arithmetic unit 4 stops reading the ECG data, performs the above-described arithmetic operation shown in FIG. 2 until the end of the data, and records the heart rate M at that time in the recording device 8.

As described above, by detecting the difference between the local maximum value and the amplitude of the ECG data generated after the local maximum value based on the threshold value, the peak of the R wave is recognized by an extremely simplified algorithm. be able to. According to this method, even if the ECG waveform drifts due to body movement, the peak of the R wave can be reliably detected. Furthermore, by surely detecting the peak of the R wave, RR
Interval and heart rate can be reliably obtained in near real time.

Since the second embodiment has the same device configuration as the first embodiment, a detailed description of the device configuration will be omitted. In the present embodiment, the ECG waveform is read, the R wave is recognized, and the RR is read by the method described below.
Interval measurement, heart rate measurement.

The operator informs the subject that the main measurement will be performed,
A command for instructing the start of ECG waveform measurement is input from the command input device 7. The calculation unit 4 detects the R wave and the S wave by multiplying the representative value of the amplitude difference between the tentative R wave peak and the S wave peak determined in advance, for example, by 70% based on the measured value from the memory. Call the threshold L1. Then, the calculation unit 4 captures the ECG waveform and records the data in the recording device 8 while storing it in the memory. In general, the difference in amplitude between the R and S wave peaks is very large compared to the difference in amplitude between the local peaks of other consecutive peaks and troughs. Therefore, a value that can absorb individual differences in this way is set as the threshold L1.
Setting it to is also not practical but sufficiently practical. When an empirical value is used for the threshold L1, there is an advantage that the preliminary measurement as in the first embodiment does not have to be performed.

FIG. 3 is a flow chart of the operation of the second embodiment. Amplitude value of ECG data is A
(N) and n = 0. In step S11, the calculation unit 4 reads the first amplitude value A (0) of the ECG data and sets it as the temporary maximum value MAX. Then, step S12
, N = n + 1, and E in step S13
The next amplitude value A (1) of the CG data is read and MAX-
It is determined whether A (1)> 0. If No, the process proceeds to step S14, A (1) is set to the temporary maximum value MAX, the process proceeds to step S15, the number T1 = n to be used in step s19 is set, and the process returns to step S12.

Then, if Yes in step S13, the process proceeds to step S16 and MAX-A
It is determined whether (n)> L1. If No, the process proceeds to step S12, n = n + 1 is set, the next amplitude value A (2) of the ECG data is read, and the process proceeds to step S13 to perform the above-described calculation.

If Yes in step S16, the flow advances to step S17 to determine that the maximum value MAX is the peak of the R wave. Then, the calculation unit 4 stores the time of the maximum value MAX in the memory as the peak time T1 of the first R wave and the heart rate M = 1.

In many cases, MAX is generated before the S wave is generated.
It is possible to set the threshold value L1 so that −A (n)> L1. However, if MAX−A (n)> L1 is satisfied, even if the peak of the S wave occurs, it is general. Will be able to recognize the R wave peak 50 to 150 msec after the R wave is generated.
The peak of the R wave can be recognized almost in real time.

Such calculation is sequentially repeated, and the peak time T2 of the second R wave, ..., And the peak time TM of the Mth R wave are recorded in the recording device 8, and the heart rate M is recorded each time.
Is called from the memory and 1 is added to re-store the heart rate in the memory. Further, the RR interval is calculated from the peak time of the R wave and displayed on the display device 6. It is obvious that if the peak of the R wave can be recognized, the RR interval and the heart rate can be calculated instantaneously, and in the end, the heart rate and the R rate can be calculated almost in real time.
-R intervals can be calculated and displayed.

After the peak of the R wave is recognized in step S17, A (n) is set to a temporary local minimum value MIN in step 18. In step S17, it is confirmed whether the difference between n at this time and T1 determined in step S15 is K or more. It is assumed that the S wave peak occurs within 200 msec at the longest from the R wave peak. For example, when ECG data is sampled at 5 msec intervals and the minimum value between 200 msec from the R wave peak is recognized as the S wave peak, K is set to 40. Since T1 is n when the peak of the R wave occurs, n−T1 ≧
When it becomes K, it is determined that the peak of the S wave has already occurred. The steps after step S18 are a flow for obtaining a local minimum value for 200 msec after the peak of the R wave.

If n-T1≥K, the process proceeds to step S20, n = n + 1, and further proceeds to step S21. In step S21, the temporary local minimum value MIN is A
If it is smaller than (n), the temporary local minimum value MIN remains unchanged and the process returns to step S19. If the temporary local minimum value MIN is greater than or equal to A (n), the process returns to step S18, and A (n) at this time is changed to a new temporary local minimum value MI.
Let N. Hereinafter, the same process is repeated, and step S1
When n-T1 ≧ K in step 9, step S22
Then, the temporary local minimum value MIN at this time is recognized as the peak of the S wave, and the difference D in amplitude between the peak of the R wave and the peak of the S wave is calculated and stored in the memory.

By repeating this operation below,
In each case, the R wave peak and the S wave peak can be recognized. When the recording is stopped, the operator inputs the command input device 7
Enter the command from. Operation unit 4 that received the command
Stops reading the ECG data, performs the above-described calculation shown in FIG. 3 until the end of the data, and records the heart rate M at that time in the recording device 8.

In this way, by detecting the difference between the local maximum value and the amplitude of the ECG data generated after the local maximum value based on the threshold value, the peak of the R wave and the peak of the R wave are detected by a very simplified algorithm. The peak of the S wave can be recognized. Then, according to this method, E
Even if the CG waveform drifts, the peak of the R wave can be reliably detected. Further, by surely detecting the peak of the R wave, the RR interval and the heart rate can be reliably obtained in almost real time.

Further, since the difference D between the amplitude values of the R wave peak and the S wave peak can be measured by recognizing the S wave peak, it is also possible to calculate the average value of the difference D. It is also possible to reset the empirically determined threshold value L1 based on the actual measurement value, and the reliability of R wave recognition can be increased.

According to the present embodiment, by setting the threshold value L1 to a value that is empirically determined, it is not necessary to carry out a preliminary experiment, and the time can be shortened. Also, recognizing the peak of S wave,
The difference D between the amplitude values of the R wave peak and the S wave peak is measured,
By resetting the threshold L1 based on this value, the reliability of the threshold L1 can be improved without conducting a preliminary experiment.

In the present embodiment, for example, R
After the peak of the wave is generated, abrupt body movement occurs within 50 to 150 msec, the peak of the S wave rises sharply, and the difference between the peak of the R wave and the peak of the S wave becomes smaller than the set threshold value. Therefore, the R wave cannot be recognized correctly. However, such a thing is extremely rare, and it is practical because it can be measured with almost no problem in normal measurement.

[0039]

As described above, the R-wave recognition method, the RR interval measuring method, the heart rate measuring method, the RR interval measuring apparatus, and the heart rate measuring apparatus according to the present invention use the R- In an R wave recognition method for recognizing an R wave for the purpose of measuring an R interval and a heart rate, (a) a local peak value of a mountain of an ECG waveform is detected, and its temporal position and amplitude are stored, ( b) calculating the difference between the local peak value of the peak of the ECG waveform and the amplitude value of ECG data thereafter, (c)
If the difference between the local peak value of the mountain and the amplitude value of ECG data thereafter is larger than a predetermined threshold value, the local peak value of the mountain of the ECG waveform is recognized as the peak of the R wave.
(D) By repeating (a) to (c) in sequence until the end of the ECG waveform, erroneous detection of the R wave can be eliminated, and the RR interval and heart rate can be measured accurately and almost in real time. It becomes possible.

Further, by determining the predetermined threshold value based on the difference between the amplitudes of the R wave peak and the S wave peak measured in advance, the R wave can be detected with higher accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a flow chart diagram of a calculation according to the first embodiment.

FIG. 3 is a flow chart diagram of a calculation according to a second embodiment.

FIG. 4 is a drifting ECG waveform diagram.

[Explanation of symbols]

1 Heart potential electrode 2 living body amplifier 4 computing section 5 R / F section 6 Display device 7 Command input device 8 recording devices

Claims (10)

[Claims] 1. An R wave recognition method for recognizing an R wave in order to measure an RR interval or a heart rate from an ECG waveform, by detecting a local peak value of a mountain of the ECG waveform, and detecting the temporal position thereof. A first step of storing the amplitude; and the ECG
The second step of calculating the difference between the local peak value of the peak of the waveform and the amplitude value of the ECG data thereafter, and if the difference between the amplitude values obtained in the second step is larger than a predetermined threshold value, A third step of recognizing a local peak value of a peak of the ECG waveform as a peak of an R wave, and a fourth step of sequentially repeating the first to third steps until the end of the ECG waveform. R wave recognition method characterized by: 2. The R wave recognition method according to claim 1, wherein the predetermined threshold value is a value determined based on a difference between peak amplitudes of the R wave and the S wave measured in advance. 3. R measuring the RR interval from an ECG waveform
-In the R-interval measuring method, a first step of detecting a local peak value of the peak of the ECG waveform and storing the temporal position and amplitude thereof; a local peak value of the peak of the ECG waveform and subsequent steps; The second step of calculating the difference between the amplitude values of the ECG data, and if the difference between the amplitude values obtained in the second step is larger than a predetermined threshold value, the local peak value of the peak of the ECG waveform is set to R. A third step of recognizing a wave peak and the first to third steps are sequentially performed by the ECG.
An RR interval measuring method comprising: a fourth step of repeating until the end of the waveform; and a fifth step of sequentially calculating a difference between the temporal positions of the R waves to obtain an RR interval. 4. The RR interval measuring method according to claim 3, wherein the predetermined threshold value is a value determined based on a difference in amplitude of peaks of the R wave and the S wave measured in advance. . 5. A heart rate measuring method for measuring a heart rate from an ECG waveform, the first step of detecting a local peak value of a mountain of the ECG waveform, and storing the temporal position and amplitude thereof, the ECG waveform Second step of calculating the difference between the local peak value of the mountain and the amplitude value of ECG data thereafter, and if the difference between the amplitude values obtained in the second step is larger than a predetermined threshold value, The third step of recognizing the local peak value of the peak of the ECG waveform as the peak of the R wave and storing the number of times the R wave is generated, and the first to third steps are sequentially repeated until the end of the ECG waveform. A fourth step of calculating a heart rate, and a heart rate measuring method. 6. The heart rate measuring method according to claim 5, wherein the predetermined threshold value is a value determined based on a difference between the peak amplitudes of the R wave and the S wave measured in advance. 7. An R measuring an RR interval from an ECG waveform
-In the R-interval measuring device, the local peak value of the peak of the ECG waveform is detected, and the difference between the local peak value of the peak of the ECG waveform and the amplitude value of the ECG waveform measured thereafter is a predetermined threshold value. If it is larger than the above, the step of recognizing the local peak value of the peak of the ECG waveform as the peak of the R wave and storing the temporal position of the R wave is sequentially repeated until the end of the ECG waveform, and the R wave is recognized. R-R is provided with R-wave recognition means and RR-interval calculation means for sequentially calculating RR intervals from the temporal positions of the plurality of R-waves.
Interval measuring device. 8. The RR interval according to claim 7, wherein the predetermined threshold value is a value determined based on a difference between the amplitudes of the R wave peak and the S wave peak measured in advance. measuring device. 9. A heart rate measuring device for measuring a heart rate from an ECG waveform, detecting a local peak value of a mountain of the ECG waveform, and measuring the local peak value of the mountain of the ECG waveform and thereafter. If the difference from the amplitude value of the ECG waveform is larger than a predetermined threshold value, the local peak value of the peak of the ECG waveform is recognized as the peak of the R wave, and the step of storing the number of times of the R wave is sequentially stored. A heart rate measuring device comprising: a heart rate calculating means for repeatedly calculating the heart rate until the end of the waveform. 10. The heart rate measuring device according to claim 9, wherein the predetermined threshold value is a value determined based on a difference in amplitude between the R wave peak and the S wave peak measured in advance. .