JPS63290543A - Stertor detector - Google Patents

Abstract

PURPOSE:To reduce the irregularity of the detection accuracy of artery stertor due to an individual difference, by setting a cardiac sound take-in range to a range suitable for detecting the blood flow sound of the coronary arteries from the cardiac sound shown by a cardiac sound signal. CONSTITUTION:The electrocardiographic signal corresponding to action potential and the cardiac sound signal corresponding to cardiac sound are respectively outputted from an electrocardiograph 10 and a phonocardiograph 14 and read in a CPU 20 through an A/D converter 18. The CPU 20 detects the second sound accompanied by the closure of the aortic valve and sets a cardiac sound data take-in range on the basis of the generation time of the second sound. The analytical result of the presence of the constriction obtained by the CPU 20 is displayed on a display device 28.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a device for detecting stenosis sounds in coronary arteries based on heart sounds generated from the heart, and particularly relates to a stenosis sound detection device in which the detection accuracy of stenosis sounds does not vary due to individual differences. It is related to the device.

BACKGROUND OF THE INVENTION Knowing the presence or absence of arterial stenosis is important in managing the health of a living body, and in particular, coronary artery stenosis may cause coronary circulatory insufficiency or myocardial infarction. For this reason, a stenosis sound detection device is being considered that is equipped with a heart sound sensor that detects heart sounds generated from the heart and outputs a heart sound signal representing the heart sound, and that detects the sound of coronary artery stenosis from the heart sound represented by the heart sound signal. .

Here, the heart sounds represented by the above-mentioned heart sound signal include the first sound and the second sound that occur with the closure of the mitral valve and the aortic valve. When detecting blood flow sounds, it is desirable to incorporate heart sound signals during the diastolic phase of the heart, which is relatively quiet after the occurrence of the first sound, as heart sound data for detecting stenosis sounds. The recording range of the heart sound data is set based on the generation time of the first sound or the generation time of the R wave of the electrocardiogram.

Problems to be Solved by the Invention However, in such conventional stenosis sound detection devices, there has been a problem in that the accuracy of detecting patients with stenosis varies due to individual differences.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The purpose is to ensure that the accuracy of detecting patients with stenosis does not vary due to individual differences.

In order to achieve such an object, the present invention includes a heart sound sensor that detects heart sounds generated from the heart and outputs a heart sound signal representing the heart sound, and detects a patient with coronary artery stenosis from the heart sound represented by the heart sound signal. A constriction sound detection device comprising:
(a) Sound detection means for detecting the sound ■ accompanying the closure of the aortic valve from among the heart sounds represented by the heart sound signal, and (b) the time of occurrence of the sound ■ detected by the sound detection means. and a sampling range setting means for setting a sampling range for capturing heart sound data for detecting the patient with stenosis, based on the above.

Effects of the Invention Namely, the present invention is capable of adjusting the time interval between the generation time of the R wave of an electrocardiogram and the generation time of the first sound accompanying the closure of the aortic valve, or Focusing on the fact that the time interval between the time of occurrence and the time of occurrence of the first sound varies due to individual differences, the first sound detection means detects the second sound and detects the second sound. The acquisition range of heart sound data is set by the acquisition range setting means based on the time of occurrence.

In this way, the range suitable for detecting coronary blood flow sounds from the heart sounds represented by the heart sound signal, that is, the relatively quiet range after the sound ① occurs, will always be available regardless of individual differences. Since this is set as the recording range of heart sound data, variations in detection accuracy of arterial stenosis due to individual differences are reduced.

The sound (2) detecting means is preferably configured to detect the sound (2) from a detection range determined based on the time of occurrence of the R wave of the electrocardiogram, but it is possible to detect the sound (2) without using the electrocardiogram. It is also possible to detect the third tone based only on the signal.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, numeral 10 is an electrocardiograph for detecting the action potential of the heart, and is equipped with a plurality of electrodes 12 that can be adhered to the chest of a living body or the like. Further, numeral 14 is a phonocardiograph as a heart sound sensor for detecting heart sounds generated from the heart, and is equipped with a microphone 16 placed on the chest of the living body. These electrocardiographs 1
0 and the phonocardiograph 14 output an electrocardiographic signal SE corresponding to the action potential and a heart sound signal SH corresponding to the heart sounds, and these signals SE and SH are converted into digital signals SED and SED in the A/D converter 18, respectively. After being converted to SHD, the CPU 20
is loaded into. The CPU 20 is supplied with an activation signal SA and a pulse signal SP of a predetermined frequency from the push button PB and the clock signal source 22, respectively.

The CPU 20, which includes a RAM 24 and a ROM 26, constitutes a microcomputer, and uses the temporary storage function of the RAM 24 to perform signal processing according to a program stored in the ROM 26 in advance, and outputs a display signal DD to the display 28 to prevent stenosis. Display the presence/absence analysis results. Second
The figure is an example of a flowchart showing such signal processing logic, and the operation of this embodiment will be explained below according to this flowchart.

First, when a power switch (not shown) is turned on, step S1 is executed through an initialization step (not shown), and a check is made to determine whether or not the push button PB has been pressed, in other words, the start signal SA
It is determined whether or not it is being supplied. When the activation signal SA is supplied, step S2 is then executed, and the counting content t of the timer that counts the pulse signal SP supplied from the clock signal source 22 is reset, and step S3 is subsequently executed. Ru. In step S3, it is determined whether the count t of the timer has exceeded 35 seconds, and the steps from step 34 onwards are repeated until 35 seconds have elapsed.

In step S4, the timing signal ST is output to the A/D converter 18 at a predetermined constant sampling period, approximately 0.444 msec (2250 Hz in frequency) in this embodiment, thereby Read the electric signal SED and heart sound signal SHD,
Next, step S5 is executed. This step S5 is
Based on the electrocardiogram signal SED read in step S4, as shown in FIG.
, is determined as . Note that the horizontal axis in FIG. 3 indicates the sampling period (approximately 0.444 msec) as lp (point).

Here, in order to eliminate the influence of periodic noise caused by the commercial AC power supply, the synchronization signal SED (II) is set to the same period as the commercial AC power supply among the electrocardiogram signals SED read in step S4, and in this embodiment. Now, two electrocardiographic signals 5ED(i) and SED u read at a period of 1/60 seconds (strictly speaking, the sampling period x 37)
, +q), the electrocardiographic signal S E D when the change rate becomes larger than a predetermined darkness value.
<i*3. ) is determined as the synchronization signal SEDtw=〉, and usually the electrocardiogram signal SED
, 5) corresponds to the peak of the Q wave of the electrocardiogram, the electrocardiogram signal SED+,. 11. is determined as the synchronization signal SED (R1).The electrocardiographic signal SED,. It's an electric signal.

Then, when the reference time P1 is determined in this way,
Next, step S6 is executed, and the first sound generated due to the closure of the mitral valve is detected from among the heart sounds represented by the heart sound signal SHD. As shown in FIG.
7 as a reference, according to the following formula (1), and its intake range W.

The difference between the maximum peak E11 on the + side and the maximum peak llt on the one side of the heart sound signal SHD within the range, that is, the maximum amplitude, is determined as the amplitude A1 of the first sound.

Furthermore, the time of occurrence of the later peak of these peaks l11 and 11t, the maximum peak 2□ on the + side in the figure, is determined as the time of occurrence PH1 of the first sound.

Wl = 0 to 300p (#0 to 133 msec) (1) Step S7 is then executed, and in substantially the same way as step S6 above, the heart sounds represented by the heart sound signal SHD are selected from the heart sounds associated with the closure of the aortic valve. The third sound generated by the sound is detected. That is, first, a sampling range W8 for detecting the sound ① is set according to the following equation (2) using the time P as a reference.

The maximum peak 121 on the + side and the maximum peak on one side of the heart sound signal SHD within! . The difference between the values is the amplitude A2 of the th note.
and their peak ffi! +
And the peak that occurred later among 2□2, in the figure, the time of occurrence of the maximum peak l□2 on one side is the time of occurrence of the th sound PI
(Determined as Z. In this embodiment, the above-mentioned step S7 and the above-mentioned step S out of a series of signal processing logic
The part that executes step 5 corresponds to the sound detection means (2), and the acquisition range W2 is the detection range of the sound (2) determined based on the reference time Pi synchronized with the R wave.

wt-soo~1100p (=266~488ms) (2) Then, when the first sound and the ■th sound are detected in this way, step S8 is executed, and the capture range W, is determined. This acquisition range W3 is for acquiring heart sound data for analyzing the presence or absence of coronary artery stenosis.
Based on the generation time Pa1t of the sound ①, it is set to a range in which the generation of sounds accompanying the opening and closing of heart valves is small and blood flow sounds in the coronary arteries can be detected. Specifically, the start time P of the intake range W is determined according to the following formula (3), and the end time Py of the intake range W is determined according to the following formula (4).
is determined, and the heart sound signal SHD during that time is taken in as heart sound data in step S9.

① Intake range W based on the generation time pHt of sound.

The reason for setting is that in order to detect blood flow sounds in the coronary arteries, it is desirable to collect heart sound data from a relatively quiet range after the occurrence of the first sound. This is because the time interval between the reference time P7, which is synchronized with the PHI or R wave, and the generation time pHt of the sound ① varies depending on individual differences.

Px=PMt+250p (#PHz+111ms) ...+3)Py
-PX +512p ("PM" 227rn seconds)...+4) Here, the end time Py obtained from the above formula (4) is calculated by the following formula (
If the condition 5) is satisfied, the new end times p, l
is determined according to the following equation (6), and this end time Py °
The intake range W3 is set based on.

P and l in the equations (5) and (6) are determined by the step S
This is the time that synchronizes with the R wave that occurs next to the R wave that is the basis of the reference time P7 found in step 5, and is determined in the same manner as the reference time P7, and its value is determined based on the reference time Pa. . This is to prevent the heart sound signal SHD from being captured as heart sound data during a period of about 200 msec before the R wave occurs, since blood flow in the coronary arteries almost stops. be. In this example,
The portion of the series of signal processing logic that executes step S8 above corresponds to the acquisition range setting means.

Py >P,,l -4501) (#P-+ 200ms)...(5)P,'=P□
r 450p (6) In step S9 above, when the heart sound data within the capture range W3 is captured, steps 310 to S12 are then executed, and the captured heart sound data and its capture conditions are set to 3. Two conditions-1, II.

It is determined whether or not each of the above conditions is satisfied, and if even one of them is not satisfied, the heart sound data is excluded from the analysis data for analyzing the presence or absence of arterial stenosis, and the steps from step 83 onwards are excluded. The execution is repeated to incorporate new heart sound data. Below, the above three conditions-I
, n, I[[ will be explained.

First, in step SIO, it is determined whether the captured heart sound data satisfies the following condition -2. In other words, the amplitude A is the difference between the maximum peak on the + side and the maximum peak on one side of the captured heart sound data.
, and the average value of the amplitude A1 of the first sound and the amplitude A of the second sound is calculated according to the following formula (7), and the amplitude ratio Z is set to a predetermined constant value of 0.5. It is determined whether or not it is less than or equal to the following. And the amplitude ratio Z is 0.5
In the following cases, the next step Sll is executed, but 0
．． If the value is greater than 5, steps 83 and subsequent steps are executed to acquire new heart sound data.

Z=A3/((A,+A,)/2)...(7
)Z≦0.5... (Condition -■)
This is the heart sound signal SHD supplied from the phonocardiograph 14.
Since this includes not only heart sounds generated from the heart, but also noise from the activities of various parts of the body, especially breathing sounds, heart sound data with an amplitude larger than the amplitude of stenosis sounds associated with abnormal coronary artery stenosis is They are excluded from the analysis data in order to improve the accuracy of the presence/absence analysis. Also, this condition -■ is the amplitude A r of the first heart sound and the second heart sound.
, Az is set as the standard for phonocardiograph 1.
This is to eliminate the influence of the mounting conditions of the microphone 16 in No. 4 and individual differences, and the reason why we decided to judge the amplitude ratio Z using 0.5 as a standard is because it has been empirically determined that the amplitude of the stenosis sound associated with stenosis abnormality is This is because the amplitudes A + and A z were never larger than 1/2 of the average value.

If the condition -■ is satisfied in step S10, step 311 is executed next, and it is determined whether the following condition -■ is satisfied. That is,
First, as shown in FIG. 3, around the first sound generation time PH1 and the second sound generation time put, a total of 750 p (approximately 333 msec) of inspection range was conducted before and after each of them. K.

At the same time, set 2 in the inspection range, 2 in 3 areas of 250p each, , ni, □ and K13.
, Ktl, Kz□ and Kt3. and,
Root mean square RMS of 1□ in the center area of + in the inspection range
(K, □) is in the area K11 on both sides and 2 of 3
The root mean square RMS (K++) and RMS (K+*) are both greater than that value, and the root mean square RMS (K2□) of 2□ is in the center area of 2 in the inspection range.
area on both sides) (root mean square RM of z+ and KI3
It is determined whether S (K++) and RMS (KI3) are greater than or equal to that value, and the root mean square RMS
If both KIRI and RMS (Kzz) satisfy the conditions, the next step 312 is executed, but if either one is not satisfied, steps 83 and subsequent steps are executed.

(Condition-■) This is to determine whether the first sound and the second sound detected in steps S6 and S7 are both appropriate. If it is satisfied, there is a high possibility that there is little noise such as breathing sounds and the first and second sounds were properly detected, but if this is not the case, the occurrence time is determined based on the peak of the heart sound signal SHD caused by noise. It is considered that PMl+PH2 has been determined, or that large noise is mixed before and after it. and,
The reliability of the heart sound data collected based on the generation time PH2 of the erroneously detected sound 2 is low, and the reliability of the heart sound data collected based on the generation time PH2 of the erroneously detected sound 2 is low, and the The credibility of the judgment result of the condition-I is also low. Therefore, even if heart sound data satisfies condition -■, if it does not satisfy condition -■, it is excluded from analysis data for analyzing arterial stenosis.

In the above step Sll, it is determined whether the condition -■ is satisfied and the following condition -■ is satisfied. In other words, the time width of the heart sound data acquisition range W3 is 300p.
It is determined whether or not the number is 300p or more, and if it is 300p or more, the next step S13 is executed, but if not, the steps from step 83 onwards are executed.

L≧300p (#133msec)...(Condition-■) This is because if the time width of the acquisition range W3 is too small, it is difficult to analyze arterial stenosis. This is because there is a high possibility that the generation time pHt of the second sound was detected incorrectly.

Such a condition - ■ means that the end time of the intake range W is the above (
If the end time is determined by the formula (4), it is unconditionally satisfied, but if the end time is determined by the formula (6), it may not be satisfied.

If the above-mentioned conditions -1, Il, and I[[ are all satisfied, then the queuing process in step S13 is executed. In this queue, as shown in FIG. 4, step R1 is first executed to determine the number of heart sound data, that is, analysis data, already stored in the data memory of the RAM 24 for analyzing arterial stenosis. It is determined whether the number is a predetermined constant number 9 or not. This constant number 9 is the number of analysis data required for the stenosis analysis in this embodiment, and the 35 seconds in the step S3 can be calculated by collecting the heart sound data for each heart beat for that period. This is because nine or more pieces of heart sound data satisfying all of the three conditions -r, n, and m are usually obtained.

In the above step S13, if the number of analysis data is 8 or less, step R2 is executed, and the above step S9
The heart sound data taken in is stored in the data memory as analysis data.

Further, when the number of analysis data is 9, step R3 is executed, and the amplitude ratio Z of the condition -■ regarding the heart sound data searched in step S9 is stored in the stored 9
It is determined whether the amplitude ratio Z of each of the two analysis data is smaller than the maximum value 1.8Z, and if it is smaller, in step R4, the analysis data having the maximum amplitude ratio wax Z is replaced in step S9. The new heart sound data entered is stored in the data memory as analysis data.

This is because even if the heart sound data has pre-stenosis data due to arterial stenosis, the relatively large amplitude ratio Z is considered to contain a correspondingly large amount of noise, and the smaller the amplitude ratio Z, the less noise there is. This is because appropriate analysis of arterial stenosis can be performed.

When step S13 is completed in this manner, steps 83 and subsequent steps are repeated for each heartbeat until the timer count t reaches 35 seconds, and after 35 seconds, step S14 is executed following step S3. be done. In step 314, it is determined whether the number of analysis data stored in the data memory is 9, and if 9 analysis data are stored, then step s1
5 is executed, but if the number of analysis data is still less than 9, step S15 is not executed and step S15 is executed.
16 is executed, and an analysis impossible display is displayed on the display 28. This means that in this embodiment, at least nine pieces of analysis data are required to perform the stenosis analysis in step S15 with high accuracy, and nine pieces of analysis data cannot be obtained in 35 seconds. is an electrocardiograph 10 or a phonocardiograph 1
This is because it is thought that there was some kind of problem with the method of measuring action potentials and heart sounds according to No. 4, the condition of the subject, the measurement environment, etc.

In step 315, the presence or absence of coronary artery stenosis is analyzed based on the nine pieces of stored analysis data. This constriction analysis is performed, for example, by frequency analysis (Fast Four
The presence or absence of stenosis and the degree of stenosis of the coronary artery are determined. Then, in the next step 316, the determination result is displayed on the display 28.

Here, in this embodiment, since the recording range W3 of the heart sound data is set based on the generation time PM2 of the 2nd sound, the reference time P1 and the generation time P of the 1st sound. Compared to the case where the sampling range W is set based on 1, there is less variation in the sampling range W due to individual differences, and it is easier to detect blood flow sounds in the coronary artery from among the heart sounds represented by the heart sound signal SHD. Heart sound data is always taken from a range suitable for this, that is, a relatively quiet range after the sound ① occurs, and variations due to individual differences in the detection accuracy before stenosis in the stenosis analysis are reduced.

In addition, in this embodiment, the heart sound signal S for detecting the third sound
Since the HD acquisition range Wt is set based on the reference time Pn that is synchronized with the R wave of the electrocardiogram, the first sound can be detected with high accuracy, and the generation time P of the second sound can be detected with high accuracy.
M! There is an advantage that the heart sound data acquisition range W can be set with high precision based on .

Furthermore, in this embodiment, among the heart sound data taken in step S9, only nine heart sound data that satisfy all conditions -1, II, and III and have a small amplitude ratio Z are analyzed as analysis data. As a result, the influence of noise such as breathing sounds is reduced during stenosis analysis, which makes analysis easier, improves analysis accuracy, and provides high reliability in stenosis determination results. .

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, the generation time PH2 of the sound ① is the electrocardiogram signal SE
The sound is determined within the sampling range W2 set with reference time Pn based on the heart sound signal SHD as a reference, but the first sound may be directly detected based on changes in the amplitude of the heart sound signal SHD, or The first sound can be detected from the amplitude change of the heart sound signal SHD, and then the second sound can be detected based on the first sound. ■Sound generation time Pl
(! can also be determined.

Further, the above-mentioned occurrence time PHI is determined by the peak that occurs later of the + side maximum peak 12° and the − side maximum peak itz of the heart sound signal SHD within the acquisition range W2, for example. The method of determining the generation time PH2 of the sound ① can be changed as appropriate, such as determining it based only on the peak on the + side, and the range W3 for capturing heart sound data may vary depending on the method of determining the generation time PHt. subject to change.

Furthermore, in the above embodiment, when the end time P of the heart sound data acquisition range W satisfies the equation (5), the end time Py° calculated by the equation (6) is applied. However, there is no problem in always applying the end time Py determined by equation (4).

Furthermore, in the embodiment described above, only the heart sound data that satisfies a certain condition among the heart sound data taken in step S9 is analyzed for stenosis as analysis data, but all the heart sound data taken in step S9 are analyzed. It is also possible to perform analysis processing as data, and various analysis methods may be employed in the stenosis analysis in step S15. In short, the content of subsequent processing of the heart sound data captured in step S9 can be determined as appropriate.

Although other examples are not given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the configuration of a constriction sound detection device that is an embodiment of the present invention. FIG. 2 is a flowchart illustrating the operation of the apparatus of FIG. 1. Figure 3 is the first
3 is a time chart illustrating signal changes, the signal acquisition range, and the inspection range in the illustrated apparatus. Figure 4 is the third
3 is a flowchart illustrating the queue shown in the figure. 14: Phonocardiograph (heart sound sensor) 20: CPU 24: RAM26: RO
M 5H, SHD: Heart sound signal W! : Acquisition range (detection range) of the ■th sound W3: Acquisition range P of heart sound data, □: Occurrence time of the ■th sound Step S5. S7: Sound detection means Step S8: Incorporation range setting means Applicant: Korin Electronics Co., Ltd. Figure 1 Figure 4

Claims (2)

[Claims] (1) A stenosis sound detection device that includes a heart sound sensor that detects a heart sound generated from the heart and outputs a heart sound signal representing the heart sound, and detects a stenosis sound of a coronary artery from the heart sound represented by the heart sound signal, the device comprising: A sound II detection means detects a sound II associated with the closure of the aortic valve from among the heart sounds represented by the heart sound signal, and the stenosis sound is detected based on the generation time of the sound II detected by the sound II detection means. 1. A stenosis sound detection device comprising: a sampling range setting means for setting a sampling range for capturing heart sound data for detecting heart sound data. (2) Constriction sound detection according to claim 1, wherein the second sound detection means detects the second sound from a detection range determined based on the generation time of the R wave of the electrocardiogram. Device.