JP2007144229A - Phonocardiograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phonocardiograph which can make a precise diagnosis of heart disease. <P>SOLUTION: A cardiac sound waveform of a given interval which includes a sound II generated for each beat from a cardiac sound signal SH is extracted as an extraction waveform WEn in a waveform extraction means 42 (SA3). The phases of the extraction waveform WEn is focused so that they mutually conform to in a phase focusing means 58 (SA9). A normal cardiac sound generated for each beat and a heart murmur are lapped, and the outside noise is averaged by the phase which adds the focused extraction waveform WEn in an addition means 60 (SA9). In addition, since a representative extraction waveform WR is decided based on a waveform which is added and obtained in the addition means 60 (SA9) in a representative extraction waveform decision means 62 (SA12), a precise diagnosis of heart disease can be made using the representative extraction waveform WR. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heart sound meter that detects a heart sound generated from a living heart and measures a heart sound diagram in order to diagnose a heart disease.

  In order to examine heart disease, doctors auscultate directly by auscultation. In the diagnosis by the auscultation method, the volume and tone color of the heart sound are different depending on the individual difference of the auscultating doctors, so that the objectivity and quantitativeness are lacking, and the heart sound cannot be recorded.

  Therefore, as an alternative to auscultation or as a means to supplement auscultation, a heart sound sensor is equipped with a heart sound sensor attached to the body surface, and a heart sound diagram is measured using a heart sound meter that amplifies and records the heart sound detected from the heart sound sensor. Is done. The phonocardiogram measured by the phonocardiograph is obtained as objective information without individual differences, and can be recorded, and the phonocardiogram measured in patients with heart disease can be recorded in addition to normal heart sounds. Since heart noise generated due to the disease is included, the heart disease can be diagnosed.

  However, since the conventional heart sound meter simply amplifies and records the heart sound detected from the heart sound sensor, the measured heart sound diagram includes normal heart sounds and heart noise generated due to heart disease. In addition to external noise, that is, noise other than sound from the heart, for example, respiratory noise accompanying breathing, noise from outside the body such as footsteps, opening and closing of doors, and the like. For this reason, it has sometimes been difficult to accurately diagnose a heart disease from a heart sound diagram.

  The present invention has been made in the background as described above, and an object of the present invention is to provide a heart sound meter that can accurately diagnose a heart disease.

  The present inventor has made various studies on the background of the above circumstances, and the external noise does not occur every beat unlike normal heart sounds and heart noises, and is 4 to 5 like the respiratory noise. It has been found that the influence of the external noise can be reduced by adding a cardiac sound waveform since it occurs in a plurality of beat periods of about a beat or occurs accidentally like noise from outside the living body.

  That is, the gist of the present invention for achieving the above object is to provide a heart sound sensor that detects a heart sound generated from the heart and outputs a heart sound signal representing the heart sound, and measures a heart sound waveform represented by the heart sound signal. (A) a waveform extracting means for extracting a heart sound waveform of a predetermined section generated every period from the heart sound signal as an extracted waveform; and (b) an extracted waveform extracted by the waveform extracting means. A phase matching means for matching the phases of the extracted waveforms so as to match each other, (c) an adding means for adding the extracted waveforms whose phases are matched by the phase matching means, and (d) calculated by the adding means. Representative extracted waveform determining means for determining a representative extracted waveform based on the extracted waveform; and (e) calculating an external noise waveform from the difference between the extracted waveform extracted by the waveform extracting means and the representative extracted waveform. External noise calculating means.

  In this way, the waveform extraction means extracts the heart sound waveform of a predetermined section generated every cycle from the heart sound signal as the extraction waveform, and the phase matching means adjusts the phases of the extracted waveforms so as to match each other. By adding the extracted waveforms whose phases are matched in the adding means, normal heart sounds and heart noises generated every beat are superimposed, and the external noises are averaged. In the representative extracted waveform determining means, the representative extracted waveform is determined based on the waveform obtained by the addition in the adding means, so that the heart disease can be accurately diagnosed using the representative extracted waveform. it can. Further, since the external noise waveform indicating the magnitude of the external noise is calculated in the external noise calculation means, the external noise waveform can be used for diagnosis or analysis of external noise such as elucidation of the cause of external noise. it can.

Other aspects of the invention

  Here, preferably, the heart sound meter further includes representative extracted waveform display means for displaying the representative extracted waveform determined by the representative extracted waveform determining means on a display. In this way, since the representative extracted waveform is displayed on the display by the representative extracted waveform display means, the heart disease can be diagnosed from the displayed representative extracted waveform.

  Preferably, the heart sound meter has a two-dimensional coordinate system composed of a time axis and an amplitude axis, the extracted waveform extracted by the waveform extracting means, and the representative extracted waveform determining means determined by the representative extracted waveform determining means. It further includes comparison display means for displaying the extracted waveform so as to be simultaneously comparable. In this way, in the comparison display means, the extracted waveform extracted by the waveform extraction means and the representative extracted waveform are displayed on the two-dimensional coordinate system composed of the time axis and the amplitude axis so that they can be compared simultaneously. The external noise can be recognized from the difference between the extracted waveform and the representative extracted waveform.

  Preferably, the heart sound meter includes external noise display means for displaying the external noise waveform calculated by the external noise calculation means on a display. In this way, the external noise waveform calculated by the external noise calculation means is displayed on the display by the external noise display means, so that the magnitude of the external noise can be easily recognized.

  Preferably, the heart sound meter includes an amplitude ratio calculating unit that calculates an amplitude ratio between a maximum amplitude and a minimum amplitude of the extracted waveform extracted by the waveform extracting unit, and an amplitude calculated by the amplitude ratio calculating unit. An average value calculating means for calculating an average value of the ratio, a standard deviation calculating means for calculating a standard deviation of the amplitude ratio calculated by the amplitude ratio calculating means, and the average of the amplitude ratios calculated by the amplitude ratio calculating means Of the extracted waveforms in which the deviation from the average value calculated by the value calculation means is within a predetermined multiple of the standard deviation calculated in advance by the standard deviation calculation means, the amplitude ratio is Reference extraction waveform determination means for determining a maximum extraction waveform as a reference extraction waveform, and the phase matching means includes a reference extraction waveform determined by the reference extraction waveform determination means. Zui said extraction waveform is intended to match the phase of the extracted waveform to match each other. In this way, the amplitude ratio of the extracted waveform extracted by the waveform extraction unit is calculated by the amplitude ratio calculation unit, the average value of the amplitude ratio is calculated by the average value calculation unit, and the amplitude is calculated by the standard deviation calculation unit. A standard deviation of the ratio is calculated, and in the reference extracted waveform determining means, among the extracted waveforms, the deviation of the amplitude ratio from the average value is within a predetermined multiple of the standard deviation determined in advance. The extracted waveform that maximizes the amplitude ratio is determined as the reference extracted waveform. That is, the extracted waveform with the least external noise is determined as the reference extracted waveform from the extracted waveforms from which the extracted waveform having an abnormally large amplitude ratio such as spike noise is excluded. In the phase matching means, the phases of the extracted waveforms are matched so that the extracted waveforms match each other based on the reference extracted waveform, so that the phases of the extracted waveforms can be matched with each other with high accuracy. Therefore, the extracted waveform is added by the adding means, and the representative extracted waveform determined based on the waveform obtained by the adding by the representative extracted waveform determining means is a heart sound and heart noise generated every beat. Is more emphasized against the external noise.

  Preferably, the heart sound meter includes a reference extraction waveform update unit that updates a reference extraction waveform based on the extraction waveform added by the addition unit, and the phase matching unit includes the reference extraction waveform update unit. The phase of the updated reference extracted waveform and the phase of the extracted waveform that has not been added by the adding unit among the extracted waveforms extracted by the waveform extracting unit are made to coincide with each other, and the adding unit performs phase matching The reference extraction waveform and the extraction waveform whose phases are matched with each other in the means are added. In this way, the phase matching means matches the phase of the reference extracted waveform updated by the reference extracted waveform updating means with the phase of the extracted waveform before being added by the adding means. The reference extracted waveform and the extracted waveform whose phases are matched with each other in the phase matching unit are added, and the reference extracted waveform updating unit updates the reference extracted waveform based on the extracted waveform added by the adding unit. Therefore, for each extracted waveform, the phase of the extracted waveform and the phase of the reference extracted waveform that is sequentially updated are matched with each other, so that the phase of the extracted waveform can be matched based on one reference extracted waveform. Since the phase matching accuracy is improved in comparison, there is an advantage that a representative extracted waveform in which the heart sound and the heart noise are further emphasized with respect to the external noise can be obtained.

  Preferably, the heart sound meter includes time-frequency analysis means for analyzing the representative extracted waveform with respect to time and frequency. In this way, since the representative extracted waveform is analyzed with respect to time and frequency by the time frequency analysis means, normal heart sounds and heart noises included in the representative extracted waveform can be separated, and the heart noise can be separated. Since the occurrence time can be analyzed, there is an advantage that diagnosis based on a representative extracted waveform can be easily performed.

  Preferably, the heart sound meter includes external noise analysis means for performing frequency analysis of the external noise waveform. By doing so, the external noise waveform is analyzed by the external noise analysis means, and a plurality of signal components such as the respiratory noise and noise from outside the living body included in the external noise waveform are separated. Therefore, it is possible to diagnose respiratory diseases using the analysis spectrum of the external noise waveform subjected to frequency analysis, and it becomes easy to elucidate the cause of noise from outside the living body. It becomes easy to remove the cause.

  Preferably, the heart sound meter includes external noise analysis means for performing frequency analysis of the external noise waveform. By doing so, the external noise waveform is analyzed by the external noise analysis means, and a plurality of signal components such as the respiratory noise and noise from outside the living body included in the external noise waveform are separated. Therefore, it is possible to diagnose respiratory diseases using the analysis spectrum of the external noise waveform subjected to frequency analysis, and it becomes easy to elucidate the cause of noise from outside the living body. It becomes easy to remove the cause.

Preferred embodiments of the invention

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating the configuration of a heart sound meter 10 to which the present invention is applied.

  In FIG. 1, a microphone 12 functions as a heart sound sensor, and is fixed on the chest of the measurement subject 14 with an adhesive tape (not shown). A heart sound or the like generated from the heart of the person 14 to be measured is converted into an electric signal, that is, a heart sound signal SH, in a piezoelectric element provided inside the microphone 12 (not shown). The heart sound signal amplifier 16 is provided with four types of filters (not shown) that weaken the bass component with large energy in order to record the high sound component of the heart sound well. The heart sound signal SH output from the microphone 12 is amplified and filtered. After being waved, it is supplied to the electronic control unit 20 via the A / D converter 18.

  The pair of electrodes 22 is attached to a predetermined part of the living body in order to output an electrocardiogram signal SE indicating the action potential of the myocardium. In this embodiment, in order to measure an electrocardiogram by lead II, it is worn on the right hand and the left foot of the person 14 to be measured. The electrocardiogram signal SE output from the electrode 22 is amplified by the electrocardiogram signal amplifier 24 and then supplied to the electronic control unit 20 via the A / D converter 26. Further, the electronic control device 20 is supplied with an activation signal SS from the push button 28 and a pulse signal SP having a predetermined frequency from the clock signal source 29.

  The electronic control unit 20 includes a CPU 30, a ROM 32, a RAM 34, and a so-called microcomputer provided with an I / O port (not shown). The CPU 30 has a storage function of the RAM 34 according to a program stored in the ROM 32 in advance. By executing the signal processing while using the electrocardiogram, the electrocardiographic waveform represented by the heart sound signal SH, that is, the electrocardiogram, and the electrocardiographic induction waveform represented by the electrocardiogram signal SE, that is, the electrocardiogram, are displayed on the display screen of the display 36, Analyze the waveform and display the results.

  FIG. 2 is a functional block diagram for explaining the main part of the control function of the electronic control unit 20 in the heart sound meter 10. In FIG. 2, the waveform storage means 40 is a predetermined storage (not shown) in the RAM 34 together with the elapsed time t from the start of measurement, which counts the heart sound signal SH and the electrocardiogram signal SE based on the pulse signal SP from the clock signal source 29. Store in the area.

  The waveform extraction means 42 extracts the heart sound waveform of a predetermined section generated every period from the heart sound signal SH of a predetermined period or a predetermined number of beats (for example, 30 seconds or 30 beats) stored in the waveform storage means 40, that is, extraction. The waveform WE is extracted. FIG. 3 is an example of an electrocardiogram and an electrocardiogram represented by the heart sound signal SH and the electrocardiogram signal SE stored in the RAM 34 by the waveform storage means 40. FIG. 3 (a) is an electrocardiogram, and FIG. 3 (b) is normal. Fig. 3 (c) characteristically shows a cardiac phonogram when there is aortic stenosis, and Fig. 3 (d) characteristically shows a cardiac phonogram when there is a left atrial valve insufficiency. As shown in FIG. 3B, there are I to IV sounds in a normal heart sound diagram. Therefore, in the waveform extraction means 42, for example, the rise of the II sound is determined from the heart sound signal SH stored in the waveform storage means 40, and the heart waveform in a predetermined section from the rise point of the II sound is extracted waveform WE. Extract as Alternatively, a heart sound signal of a predetermined section after a predetermined time has elapsed since a predetermined part (for example, R wave) periodically detected in the electrocardiogram is detected using an electrocardiogram measured simultaneously with the electrocardiogram as a reference guide. The heart sound waveform represented by SH is extracted as an extracted waveform WE.

Amplitude ratio calculation unit 44, as shown in an example of the extraction waveform WE in FIG. 4, to determine the maximum amplitude D _S and the minimum amplitude D _n for each extraction waveform WE extracted by the waveform extraction unit 42, the maximum that calculating the amplitude ratio between the amplitude _{D S} and the minimum amplitude _{D n} the _(D S / D _n).

The average value calculating means 46 calculates the average value D _AV of the amplitude ratio (D _S / D _n ) calculated by the amplitude ratio calculating means 44, and the standard deviation calculating means 48 is calculated by the amplitude ratio calculating means 44. A standard deviation s of the amplitude ratio (D _S / D _n ) is calculated.

The reference extraction waveform determining unit 54 is configured such that the deviation of the amplitude ratio (D _S / D _n ) calculated by the amplitude ratio calculating unit 44 from the average value D _AV calculated by the average value calculating unit 46 is a standard deviation calculating unit. Among the extracted waveforms WE within a predetermined experimentally determined range of the standard deviation s calculated in 48, the extracted waveform WE having the maximum amplitude ratio (D _S / D _n ) is used as the reference extracted waveform. _WST is determined. That is, the extracted waveform WE whose amplitude ratio (D _S / D _n ) is not within the range of a predetermined multiple (for example, twice) of the standard deviation s that is _deviated from the average value D _AV is excluded. Thus, the extracted waveform WE having an abnormally large amplitude ratio (D _S / D _n ) such as spike noise is excluded, and the extracted waveform WE from which the abnormal extracted waveform WE such as spike noise is excluded is the largest amplitude ratio (D determining the _S / _{D n)} is greater extracted waveform WE based extraction waveform _{W ST.} Therefore, the reference extracted waveform _WST determined in this way is the extracted waveform WE with the least external noise among the normal extracted waveforms WE extracted by the waveform extracting means 42.

The permutation determining unit 56 determines the order in which the extracted waveform WE extracted by the waveform extracting unit 42 is processed by the phase matching unit 58 and the adding unit 60 described below in the amplitude ratio ( D _S / D _n ), the average value D _AV calculated by the average value calculation means 46, and the standard deviation s calculated by the standard deviation calculation means 48. That is, the amplitude ratio (D _S / D _n ) is within a range used by the reference extracted waveform determining means 54 (that is, the deviation from the average value D _AV is a predetermined multiple of the standard deviation s determined experimentally in advance). Range) is the first range, the range outside the first range is the second range, and the order in which the extracted waveform WE is processed in the phase matching means 58 and the adding means 60 is the reference extracted waveform WE _ST in the first range. except for the amplitude ratio _(D S / D _n) smaller from the larger, followed by a minimum value of the amplitude ratio from the largest amplitude ratio _(D S / D _n) in a second range _(D S / D _n) To decide. Therefore, the phase alignment means 58 and adding means 60, relatively, since the possible from the extraction waveform WE similar to the reference extraction waveform WE _ST is processed in order, it is possible to prevent the mistake of phasing, the outer noise effects Can be suitably removed.

The phase matching unit 58 matches the phase of the extracted waveform WE so that the extracted waveforms WE extracted by the waveform extracting unit 42 coincide with each other. That is, pattern matching of the extracted waveform WE is performed. For example, an extraction waveform WE extracted in the waveform extraction unit 42, is determined in the reference extraction waveform determining means 54, or to the reference extraction waveform WE _ST updated in the reference extraction waveform updating unit 61 described later is equal to each other to, adjust the phase of the extracted waveform WE based extraction waveform _{WE ST.} Alternatively, at least one phase of the extracted waveforms WE is corrected so that two or more arbitrary extracted waveforms WE extracted by the waveform extracting means 42 coincide with each other. To adjust the phase of the extracted waveform WE extracted in the waveform extraction unit 42 to the phase of the reference extraction waveform WE _ST, for example, so that its correlation coefficient with the reference extraction waveform W _ST and the extracted waveform WE is maximum The phase of the extracted waveform WE is corrected, that is, the time axis of the extracted waveform WE is shifted. Alternatively, the phase of the extracted waveform WE is corrected so that the mean square error between the reference extracted waveform _WST and the extracted waveform WE is minimized.

The adding means 60 adds the extracted waveforms WE whose phases are matched by the phase matching means 58. That is, the extraction waveform WE whose phases are aligned to match the reference extraction waveform W _ST in phase matching means 58 is sequentially added to the reference extraction waveform W _ST. Alternatively, two or more extracted waveforms WE whose phases are matched to each other in the phase matching means 58 are added at a time. For example, if the extracted waveforms for n beats are added, the signal component generated for each beat is multiplied by n, whereas the randomly generated component is only √n (square root of n) times. When the extraction waveform WE is added by the adding means 60, the signal intensity of the heart sound and heart noise generated every beat is relatively increased.

Reference extracting waveform updating unit 61 updates the reference extraction waveform W _ST on the basis of the extracted waveform WE of the addition in the adding means 60, to determine a new reference extraction waveform W _ST. That is, a waveform obtained by dividing the amplitude intensity of the added waveform added by the adding means 60 by the number corresponding to the number of the extracted waveforms WE added by the adding means 60 is used as a new reference extracted waveform _WST. decide.

  The representative extracted waveform determining means 62 determines the representative extracted waveform WR based on the extracted waveform WE added by the adding means 60. For example, the extracted waveform WE obtained by the addition in the adding means 60 is directly determined as the representative extracted waveform WR. Alternatively, the representative extracted waveform WR is determined by dividing the amplitude of the extracted waveform WE after addition by the adding means 60 by the number of added extracted waveforms.

  The representative extracted waveform display means 64 displays the representative extracted waveform WR determined by the representative extracted waveform determination means 62 on the display 36, and the comparison display means 66 has two-dimensional coordinates composed of a time axis and an amplitude axis. In the system, the extracted waveform WE extracted by the waveform extracting means 42 and the representative extracted waveform WR determined by the representative extracted waveform determining means 62 are displayed so as to be simultaneously comparable.

  The time frequency analyzing means 68 analyzes the representative extracted waveform WR determined by the representative extracted waveform determining means 62 with respect to time and frequency. For example, the representative extracted waveform WR is divided into a plurality of time zones, and the representative extracted waveform WR is analyzed for each divided time zone. Alternatively, the representative extracted waveform WR is wavelet transformed.

  The wavelet transform is a movement variable b that translates the wavelet function ψ (t), an example of which is shown in FIG. 5, in the time axis direction, and an expansion / contraction that expands or contracts the size of the waveform represented by the wavelet function in the time axis direction. As a function of the variable a, the product of the wavelet function ψ ((t−b) / a) and the function f (t) representing the representative extracted waveform WR is obtained by integrating the product of the above a and b with respect to time t. Defined as a function. That is, it is defined as Equation 1 below. In the wavelet function ψ ((t−b) / a), the width of ψ (t) is a times corresponding to the expansion / contraction variable a, so 1 / a corresponds to the frequency and the movement variable b B corresponds to time since ψ (t) translates in the time axis direction corresponding to.

  FIGS. 6 and 7 are diagrams for explaining the meaning of the wavelet transform equation of Equation 1. FIG. 6A shows that the wavelet function ψ ((t− b) / a) shows a state substantially matching a part of a function g (t), and FIG. 7A shows a function h (t) having a wavelet function ψ ((t−b) / a). The state which has not approximated a part of is shown. 6B and 7B show the wavelet function ψ ((t−b) / a) and the function g (t) or h (in the case of FIGS. 6A and 7A. It is a figure which shows each product with t). As shown in FIG. 6B, when the wavelet function ψ ((t−b) / a) substantially matches a part of the function g (t), ψ ((t−b) / a) Since the product of g and t (t) has no sign change, the integral value becomes large. However, as shown in FIG. 7B, when the wavelet function ψ ((t−b) / a) does not approximate a part of the function h (t), ψ ((t−b) / a ) And h (t), since the sign changes drastically with the change of t, the integral value becomes small. Therefore, in the above formula 1, when the parameters a and b are changed, the wavelet function ψ ((t−b) / a) resembles a part of the function f (t) representing the representative extracted waveform WR. A large value is shown, and a small value is shown when it is not similar to a part of the function f (t) representing the representative extracted waveform WR.

  The analysis result display means 70 displays the frequency analysis spectrum subjected to the time frequency analysis by the time frequency analysis means 68 on the display 36.

  FIG. 8 is a flowchart for explaining a main part of the control operation of the electronic control unit 20. This routine is executed when the push button 28 is pressed and an activation signal SS is supplied.

  First, in an initialization step (not shown), after initial processing for clearing the timer t and the register for counting the pulse signal SP supplied from the clock signal source 29 is performed, step SA1 (hereinafter referred to as the waveform storage means 40) is performed. In this case, the heart sound signal SH and the electrocardiogram signal SE are sequentially stored in the storage area of the RAM 34.

  In subsequent SA2, it is determined whether or not the count content t of the timer has passed 30 seconds. The determination of SA2 is denied until 30 seconds elapses, and SA1 and subsequent steps are repeated, whereby the heart sound signal SH and the electrocardiogram signal SE are continuously stored.

If the determination of SA2 is affirmed, in SA3 corresponding to the subsequent waveform extracting means 42, a heartbeat waveform in a predetermined section generated for each period is extracted from the heart sound signal SH stored in SA1 as the extracted waveform WE. . In SA3, a 30-second heart sound signal SH is stored, that is, 30 to 40 beats of heart sound waveform are stored, so that 30 to 40 beats of extracted waveform WE _n (n = 1 to 30 to 40) are stored. ) Is extracted. In addition, as the predetermined section, for example, an electrocardiographic waveform represented by a heart sound signal SH represented by a heart sound signal SH after 0.2 seconds from the start of an R wave in an electrocardiogram measured as a reference lead is used. Is extracted. The period of 0.2 seconds after the occurrence of the R wave of the electrocardiogram is set as a period sufficiently including the II sound useful for diagnosis, but the extracted section is limited to this section. It is not set within the range of one beat.

In SA4 corresponding to the amplitude ratio calculation unit 44 that follows, for each of the extracted extracted waveform WE _n at SA3, the amplitude ratio of the maximum amplitude _{D S} and the minimum amplitude _{D n (D S / D n} ) n is calculated . In SA5 corresponding to the subsequent average value calculating means 46, the average value D _{AV of} the amplitude ratio (D _S / D _n ) _n calculated in SA4 is calculated, and in SA6 corresponding to the subsequent standard deviation calculating means 48, The standard deviation s of the amplitude ratio (D _S / D _n ) _n calculated in SA4 is calculated.

In SA7 corresponding to the reference extraction waveform determining unit 54 that follows, the amplitude ratio deviation from the average value _{D AV} calculated is within the range of 2 times the standard deviation s calculated in SA6 in SA5 _(D S / D _n ) in the extracted waveform WE _n with _n, extracts waveform WE _n the amplitude ratio _{(D S /} D _n) n is maximum is determined as the initial reference extracted waveform _{W ST1.} That is, the amplitude ratio among the extracted waveform WE _n satisfying Equation _{2 (D S / D n)} n is extraction waveform WE _n indicating the maximum value is determined in the first reference extracted waveform _{W ST1.} In general, the range of Equation 2 includes 95% of the total extracted waveform WE _n .

[Equation 2]
_{D AV -2s ≦ (D S /} D n) n ≦ D AV + 2s
In SA8 corresponding to the subsequent permutation determining means 56, the order of the extracted waveforms WE _n used for phase alignment is determined in the next SA9. That is, the order of the extracted waveform WE _n used in the next SA9 to phasing is, among the extracted waveform WE _n ranges satisfying the above Equation 2 (i.e. extracted waveform WE _n of the first range), the amplitude ratio _(D S / D _n) towards smaller from _n large, then the amplitude ratio in the extraction waveform WE _n ranges that do not satisfy the above equation 1 (i.e. extracted waveform WE _n of the second _{range) (D S /} D n) larger _n To the minimum value of the amplitude ratio (D _S / D _n ) _n .

Then once fewer than the number n of extraction waveform WE _n extracted in the SA3 (i.e. n-1 times) only, is repeated SA9 to SA12. First, in SA9 corresponding to the phase matching means 58, the n-th reference extracted waveform W _STn determined in SA7 or updated in SA11 described later and one of the extracted waveforms WE _n determined in order in SA8 are as follows. The phase of the extracted waveform WE _n is corrected so that the correlation coefficient is maximized, or the square of the difference in amplitude intensity between the two waveforms is minimized, and SA10 corresponding to the subsequent adding means 60 In the extraction, the waveform obtained by multiplying the amplitude intensity of the n-th reference extraction waveform W _STn by the number n of the extraction waveforms WE _{used for} the calculation of the reference extraction waveform W _STn is phase-matched in SA9. Waveform WE _n is added.

In SA11 corresponding to the reference extraction waveform updating unit 61 that follows, obtained by dividing the number (n + 1) corresponding waveform obtained are summed in SA10, the number of extraction waveform WE _n which are added by the SA10 waveform _Is determined as a new reference extraction waveform _WST . That is, the reference extraction waveform _WST is updated. Then followed the SA12, extracted waveform WE _n extracted in the SA3 whether the summed total beats is determined. While the determination of SA12 is negative, SA9 and subsequent steps are repeatedly executed.

In the repetition of the above SA9 to SA12, the contents executed example the first time, first in SA9, the first reference extracted waveform _{W ST1} determined in SA7, extracted waveform WE to be added to the first determined at SA8 The phases of _n are matched, and in the subsequent SA10, the two extracted waveforms are added. In SA11, a waveform obtained by dividing the amplitude intensity of the waveform obtained in SA10 by 2 is determined as a new reference extraction waveform _WST2 . Then, in the second SA9 to SA11, first the reference extraction waveform _{W ST2} determined in previous SA11 in SA9, aligned phase extraction waveform WE _n to be added to the second determined in SA8, followed SA10 in extraction waveform WE _n whose phases are aligned with the reference extraction waveform W _ST2 in the SA9 is added to the reference extraction waveform obtained by the amplitude intensity and twice the waveform W _ST2. In SA11, a waveform obtained by dividing the amplitude intensity of the waveform obtained in SA10 by ₃ is determined as a new reference extraction waveform _WST3 .

In this way, repeated SA9 to SA11 is n-1 times, the extraction waveform WE _n extracted with SA3 is added all beats, the determination in SA12 is affirmative, the reference extraction determined in the last SA11 Waveform W _STn is determined as a representative extracted waveform WR. Therefore, SA12 corresponds to the representative extracted waveform determining means 62.

In SA13 corresponding to the subsequent representative extracted waveform display means 64, the representative extracted waveform WR determined in SA12 is displayed on the display 36 and used for diagnosis of heart disease. FIG. 9 is a diagram showing an example thereof, and since external noise is suitably removed as compared with FIG. 4 described above, diagnosis of heart disease can be performed accurately. Further, in SA14 corresponding to the subsequent comparison display means 66, as shown in FIG. 10, the extracted waveform WE _n extracted in SA3 is displayed on the two-dimensional coordinates composed of the time axis 72 and the amplitude axis 74 of the display 36. is displayed in solid lines, by a representative extraction waveform WR determined in SA12 is displayed by a broken line, the extracted waveform WE _n and representative extraction waveform WR are simultaneously displayed. Incidentally, in FIG. 10, as an example which is displayed in SA14, but one of the extracted waveform WE _n extracted in SA3 is displayed simultaneously with typical extraction waveform WR, in SA14, the time axis of the display 36 72 and the two-dimensional coordinate composed of the amplitude axis 74. all of the extracted waveform WEn extracted at SA3 is displayed simultaneously with typical extraction waveform WR, the outer noise extraction waveform WE _n from the difference between the representative extraction waveform WR And the fluctuation of the external noise can be recognized.

  In SA15 corresponding to the subsequent time frequency analysis means 68, the representative extracted waveform WR determined in SA12 is subjected to time frequency analysis. That is, the function f (t) representing the representative extracted waveform WR is wavelet transformed in accordance with Equation 1 above, and the function W (b, 1 / a).

  In SA16 corresponding to the subsequent analysis result display means 70, as shown in FIG. 11, the time axis b (that is, the movement variable axis) and the frequency axis (1 / a) (that is, the reciprocal of the expansion / contraction variable) of the display 36 are represented. The size of the function W (b, 1 / a) obtained by the wavelet transform in SA15 is displayed as a contour map on a two-dimensional plane with respect to (axis). In FIG. 11, it can be seen that a signal with a high frequency component is detected at the beginning of the time axis b, and a high frequency component is weakened over time, and instead a signal with a low frequency component is detected. The presence of heart noise and the location of the heart noise are identified by comparing the frequency range in which this signal is generated, the time at which the signal is generated, or the overall display pattern of the graph with the standard pattern of normal heart sounds obtained in advance. Diagnosis of diseases such as

As described above, according to the present embodiment, the waveform extraction means 42 (SA3) extracts the heart sound waveform of a predetermined section including the II sound generated every beat from the heart sound signal SH as the extracted waveform WE _n . The phase matching means 58 (SA9) matches the extracted waveforms WE _{n so that} the phases of the extracted waveforms WE _n coincide with each other, and the adding means 60 (SA9) adds the extracted waveforms WE _n whose phases are matched. Normal heart sounds and heart noises that occur every beat are superimposed, and the outside noise is averaged. The representative extracted waveform determining means 62 (SA12) determines the representative extracted waveform WR based on the waveform obtained by the addition in the adding means 60 (SA9), and therefore uses the representative extracted waveform WR. Diagnosis of heart disease can be performed accurately.

  Further, according to the present embodiment, the representative extracted waveform WR is displayed on the display 36 by the representative extracted waveform display means 64 (SA13), so that a heart disease is diagnosed from the displayed representative extracted waveform WR. can do.

Further, according to the present embodiment, in the comparison display means 66 (SA14), the extracted waveform WE _n extracted by the waveform extraction means 42 (SA3) is added to the two-dimensional coordinate system composed of the time axis 72 and the amplitude axis 74. since a typical extraction waveform WR determined in a representative extraction waveform determining means 62 (SA12) is comparably displayed simultaneously, recognizing the outer noise from a difference between the representative extracted waveform WR and the extracted waveform WE _n can do.

Further, according to the present embodiment, the amplitude ratio (D _S / D _n ) _{n of} the extracted waveform WE _n extracted by the waveform extraction unit 42 (SA3) is calculated by the amplitude ratio calculation unit 44 (SA4), and the average is calculated. average value _{D AV} of the amplitude ratio value calculation means 46 (SA5) is calculated, the standard deviation s of the amplitude ratio by the standard deviation calculating means 48 (SA6) is calculated, the reference extraction waveform determining means 54 (SA7) , the amplitude ratio _{(D S /} D _n) n is in the extracted waveform WE _n where deviation from the average value _{D AV} is in the range of 2 times the standard deviation s, the maximum amplitude ratio _{(D S /} D _n) n is The extracted waveform WE _n is determined as the reference extracted waveform _WST1 . That is, the amplitude ratio _{(D S /} D _n) n is unusually large extracts waveform WE _n is from the extracted waveform WE _n excluded, most the outer noise is small extracted waveform WE _n reference extracted waveform such as spike noise W _ST1 is determined. Then, the phase adjustment unit 58 (SA9), the phase of the extracted waveform WE _n are combined as the reference extract waveform _{W ST1} extracted waveform WE _n based on matches with each other, accurately extracted waveform WE _n phases Can be matched to each other. Therefore, the extracted waveform WE _n is added in the adding means 60 (SA10), and the representative extracted waveform WR determined based on the waveform obtained by the addition in the representative extracted waveform determining means 62 (SA12) is: There is an advantage that a heart sound and a heart noise generated every beat are further emphasized with respect to the external noise.

Further, according to the present embodiment, the phase of the reference extraction waveform W _STn updated by the reference extraction waveform update unit 61 (SA11) is added to the phase adjustment unit 58 (SA9) and added by the addition unit 60 (SA10). The phase of the extracted waveform WE _n is matched with each other, and the adding means 60 (SA10) has the reference extracted waveform W _STn and the extracted waveform WE _{n whose} phases are matched with each other in the phase matching means 58 (SA9). There are added, the reference extraction waveform updating unit 61 (SA11), the reference extraction waveform _{W STn} is updated based on the extracted waveform WE _n which are added by the adding means 60 (SA10). Therefore, for each extracted waveform WE _n, the reference extraction waveform W _STn which is sequentially updated with the phase of the extracted waveform WE _n since the phase is matched to one another, one being done in the Examples which will be described next since as compared with the case where the reference extracted waveform W phase extraction waveform WE _n based on the _ST is matched to improve matching accuracy of the phase, a representative heart sounds and murmurs are more are more emphasized with respect to the outer noise There is an advantage that the extracted waveform WR can be obtained.

  Further, according to the present embodiment, the representative extracted waveform WR is wavelet transformed by the time frequency analysis means 68 (SA15) to be a function of time b and frequency (1 / a), and therefore, as shown in FIG. As described above, normal heart sounds and heart noises included in the representative extracted waveform WR can be separated, and the time when the heart noises can be analyzed, so that the presence of the heart noises can be easily known, and further the generation of the heart noises. There is an advantage that the diagnosis based on the representative extracted waveform WR can be easily performed, such as being able to specify a part.

  Next, another embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, portions common to the above-described embodiments are denoted by the same reference numerals and description thereof is omitted.

  FIG. 12 is a functional block diagram for explaining a main part of the control operation of the electronic control device 20 of the heart sound meter to which another embodiment of the present invention is applied. In the heart sound meter of this embodiment, the mechanism and circuit configuration of the device are the same as those of the embodiment of FIG. 1 described above, and the control operation by the electronic control device 20 is different in the following points.

That is, in the electronic control unit 20 of this embodiment, the first reference extraction waveform W _ST1 is determined in the same manner as in the above-described embodiment, and all other extraction waveforms WE _n are matched with the reference extraction waveform W _ST1. And the phases of all the extracted waveforms WE _n are matched, and then all the extracted waveforms WE _n are added at one time to determine the representative extracted waveform WR. (Therefore, the permutation determining means 56 and the reference extracted waveform updating means 61 are not provided.) Then, the comparison is made such that the representative extracted waveform WR and the extracted waveform WE _n are displayed in a comparable manner so that the external noise can be recognized. Instead of the display means 66, the external noise is calculated from the representative extracted waveform WR and the extracted waveform WE _n, and the calculated external noise is displayed and analyzed. Hereinafter, the difference will be mainly described.

  The external noise calculating means 82 is determined by the extracted waveform WE extracted by the waveform extracting means 42 and the representative extracted waveform determining means 62 among the heart sound waveforms represented by the heart sound signal SH stored in the RAM 34 by the waveform storage means 40. The difference from the representative extracted waveform WR is calculated as the external noise waveform WN.

  The external noise display means 84 displays the external noise waveform WN calculated by the external noise calculation means 82 on the display 36, and the external noise analysis means 86 uses the external noise waveform WN calculated by the external noise calculation means 82 as the frequency. Analysis is performed and the result is displayed on the display 36.

FIG. 13 is a flowchart for explaining a main part of the control operation of the electronic control unit 20 of this embodiment. In the figure, in SB1 to SB7, the same processing as SA1 to SA7 in the above-described embodiment is performed, so that the 30-second heart sound signal SH and the electrocardiogram signal SE are stored, and the II sound generated every beat is included. An extracted waveform WE _n (n = 1 to 30 to 40) in a predetermined section is extracted. Among the extracted waveforms WE _n , the amplitude ratio is the largest in a range where the deviation from the average value D _AV is twice the standard deviation s. (D _S / D _n ) The extracted waveform WE _n that increases _n is determined as the reference extracted waveform W _ST1 .

Continued the corresponding phase alignment means 58 SB8, for all of the waveform of the extracted waveform WE _n extracted in SB3, corrected its phase to match the reference extraction waveform W _ST1 determined in SB7, followed addition means In SB9 corresponding to 60, all the extracted waveforms WE _n whose phases are corrected are added. When all the extracted waveforms WE _n are added in SB9, normal heart sounds and heart noises generated every beat are superimposed and the external noises are averaged, so that relatively normal heart sounds and heart noises are emphasized. Is done.

In SB10 corresponding to the representative extraction waveform determining unit 62 that follows, by the amplitude intensity of the extracted waveform WE _n after addition calculated in SB9 is divided by the added number of beats n, it is an amplitude intensity of one heartbeat That is, the extracted waveform WE _n having the average amplitude and the amplitude intensity for one beat is determined as the representative extracted waveform WR.

In SB11 corresponding to the subsequent representative extracted waveform display means 64, for example, as shown in FIG. 9, the representative extracted waveform WR determined in SB10 is displayed on the display 36, and corresponds to the subsequent external noise calculation means 82. in SB12, outside noise waveform WN _n for each one heartbeat from the difference between the extracted extracted waveform WE _n and representative extraction waveform WR determined at SB10 is calculated by SB3, corresponding to subsequent outer noise display means 84 SB13 The external noise waveform WN _n calculated in SB12 is displayed. Figure 14 is a diagram showing an example of the external noise waveform WN _n displayed in SB13, is calculated by a typical extraction waveform WR shown in Figure 6 from the extraction waveform WE shown in FIG. 4 is subtracted An external noise waveform WN _n is shown. Incidentally, in FIG. 14, only one exterior noise waveform WN _n are shown, in SB13, all external noise waveform WN _n calculated in SB12 is displayed on the display unit 36, their outer noise waveform From WN _n , the magnitude of the external noise and the fluctuation of the external noise can be recognized.

In SB 14 corresponding to the subsequent external noise analysis means 86, the external noise waveform WN _n calculated in SB 12 is Fourier analyzed, and the Fourier analysis spectrum is displayed on the display 36. Since the external noise waveform WN _n includes the respiratory noise having a period of 4 to 5 times the heartbeat period, and a plurality of noises accidentally generated from outside the body, such as footsteps and door opening / closing sounds, Fourier analysis is performed. Thus, these noises are separated in frequency and displayed on the display 36.

In SB15 corresponding to the subsequent time frequency analysis means 68, the representative extracted waveform WR determined in SB12 is subjected to time frequency analysis. That is, the representative extracted waveform WR is divided into a plurality of preset time zones, and frequency analysis is performed for each of the divided time zones. For example, the time zone of the representative extracted waveform WR is divided into four equal parts, which are a first zone T ₁ , a second zone T ₂ , a third zone T ₃ , and a fourth zone T ₄ , respectively. Frequency analysis is performed.

In SB15, when the representative extracted waveform WR is subjected to frequency analysis, the heart sound (II sound in this embodiment) and the heart noise have different frequency components, so the heart sound and the heart noise are separated. In addition, since the representative extracted waveform WR is subjected to frequency analysis for each of the plurality of time zones, there are time zones in which cardiac noise is included and time zones in which heart noise is not included. For example, when the representative extracted waveform WR shown in FIG. 6 is a waveform representing a synthesized sound of II sound and heart noise as shown in FIG. 15, the third section T ₃ and the fourth section T ₄ Since there is a signal that exists only in the spectrum obtained by frequency analysis of the representative extracted waveform WR, it is possible to know the presence of heart noise, and further, the type of heart noise is classified from the time of occurrence of heart noise, and the site of the disease is identified. Can be identified.

In the SB 16 corresponding to the subsequent analysis result display means 70, as shown in FIG. 16, the frequency analysis spectrum obtained as a result of the time frequency analysis in the SB 15 is a frequency axis 76, an amplitude axis 78 of the display 36, and Since there is a signal that is displayed in a three-dimensional coordinate system composed of the time zone axis 80 and exists only in the third section T ₃ and the fourth section T ₄ , it is possible to recognize the heart noise and the generation time.

As described above, according to the present embodiment, in the waveform extraction means 42 (SB3), the heart sound waveform of a predetermined section including the II sound generated every beat is extracted as the extracted waveform WE _n from the heart sound signal SH. tailored to match the phase alignment means 58 (SB8) in the extraction waveform WE _n phases of the reference extraction waveform determining means 54 (SB7) reference extracted waveform _{W ST1} is determined by the phase, the adding means 60 (SB9) By adding all n beats of the extracted waveform WE _n whose phases are matched, normal heart sounds and heart noises generated every beat are superimposed, and the external noises are averaged. The representative extracted waveform determining means 62 (SB10) determines the representative extracted waveform WR by dividing the waveform calculated by the adding means 60 (SB9) by the added number of beats n. A heart disease can be accurately diagnosed using the waveform WR.

Further, according to this embodiment, the external noise waveform WN _n indicating the magnitude of the external noise calculated by the external noise calculating means 82 (SB12) is displayed on the display 36 by the external noise display means 84 (SB13). Since it is displayed, the magnitude of the external noise can be easily recognized, and the external noise waveform WN _n can be used for diagnosis.

Further, according to the present embodiment, the external noise waveform WN _n is Fourier-analyzed by the external noise analysis means 86 (SB14), and a plurality of respiratory noises and in vitro noises included in the external noise waveform WN _n are obtained. Are separated. Therefore, it is possible to diagnose respiratory diseases using the analysis spectrum of the external noise waveform WN _n subjected to Fourier analysis, and it becomes easy to elucidate the cause of noise from outside the living body. It becomes easy to remove the cause of noise.

  Further, according to the present embodiment, the representative extracted waveform WR is divided into four time zones by the time frequency analyzing means 68 (SB15), and the frequency analysis is performed for each of the four time zones. The normal heart sound and heart noise included in the extracted waveform WR are separated, and the time zone in which the heart noise occurred is analyzed, so it is possible to easily know the presence of the heart noise and to generate the heart noise. There is an advantage that the diagnosis based on the representative extracted waveform WR can be easily performed, such as being able to specify a part.

  As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

For example, in the above-described embodiment, in the reference extraction waveform determining means 54 (SA7, SB7), the amplitude ratio (D _S / D _n ) is within the range where the deviation from the average value D _AV is twice the standard deviation s. in the extracted waveform WE _n, the amplitude ratio _(D S / D _n) has been determined extracted waveform WE _n having a maximum relative extracted waveform _{W ST,} not the amplitude ratio _(D S / D _n) is calculated , it may be determined one arbitrary extraction waveform WE _n extracted in the waveform extracting means 42 (SA3, SB3) to the reference extraction waveform _{W ST,} also extracted waveform without determining a reference extraction waveform _{W ST} The phase may be modified so that WE _n matches each other. Reference so even if the case any extraction waveform WE _n is determined based on the extraction waveform _{W ST} or reference extracted waveform _{W ST} is not determined, the reference extraction waveform _{W ST} in phase alignment means 58 (SA9, SB8) as is modified other extraction waveform WE _n phases, or the phase of the extracted waveform WE _n are modified to cross the phases coincide, normal heart sounds and murmurs by addition is superimposed, the outer noise There is a temporary effect on averaging.

In the first embodiment described above, in SA14 corresponding to the comparison display means 66, extracts waveform WE _n are displayed by broken lines, by a representative extraction waveform WR is displayed by a solid line, both comparable with However, the comparison may be made by other display methods such as display using different colors.

  In addition, the electrocardiograph of the above-described embodiment includes the electrode 22, the electrocardiogram signal amplifier 24, and the A / D converter 26 so that the electrocardiogram can be measured as a reference guide along with the measurement of the electrocardiogram. The electrocardiogram need not necessarily be measured. When an electrocardiogram is not measured as a reference guide, the waveform extraction means 42 directly detects one or two predetermined sites that are generated for each beat of the heart sound signal SH, and is preset from the predetermined site. The waveform between the predetermined sections in the two sections or the two sections is extracted.

  In the first embodiment described above, the size of the function W (b, 1 / a) obtained by the wavelet transform in the analysis result display means 70 (SA16) is the time axis b and the frequency of the display 36. Although displayed as a contour map on the two-dimensional plane with the axis 1 / a, it is displayed as a three-dimensional graph on the three-dimensional coordinates formed by the time axis b, the frequency axis 1 / a, and the axis representing the converted value. May be.

  In addition, the present invention can be variously modified without departing from the gist of the present invention.

It is a block diagram which shows the structure of the heart sound meter which is one Example of this invention. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus of the Example of FIG. It is a figure which shows an example of the electrocardiogram which the heart sound signal and the electrocardiogram signal represent, and an electrocardiogram. It is a figure which shows an example of the extraction waveform extracted by a waveform extraction means. It is a figure explaining wavelet function (psi) (t). FIG. 6 is a diagram illustrating a state in which a wavelet function ψ ((t−b) / a) substantially matches a part of a function g (t) and a product of two functions at that time. It is a figure which shows the product of two states at the time of the state which is not approximating a part of function h (t) with a wavelet function (psi) ((tb) / a). It is a flowchart explaining the principal part of the control action of the electronic control apparatus of the Example of FIG. It is a figure which shows an example of the representative extraction waveform displayed by the representative extraction waveform display means. It is a figure which shows an example by which an extraction waveform and a typical extraction waveform are displayed on a display by a comparison display means. It is a contour map displayed on a display in the analysis result display means of the Example of FIG. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus of the other Example of this invention. It is a flowchart explaining the principal part of the control action of the electronic control apparatus of the Example of FIG. It is a figure which shows an example of the external noise waveform displayed on a display in an external noise display means. It is a figure explaining that the generation | occurrence | production time zone of a cardiac noise can be specified by a time frequency analysis means. It is a figure which shows an example of the frequency analysis spectrum displayed in an analysis result display means.

Explanation of symbols

  10: heart sound meter, 12: microphone (heart sound sensor), 42: waveform extracting means, 44: amplitude ratio calculating means, 46: average value calculating means, 48: standard deviation calculating means, 54: reference extraction waveform determining means, 58: Phase matching means, 60: addition means, 61: reference extraction waveform update means, 62: representative extraction waveform determination means, 64: representative extraction waveform display means, 66: comparison display means, 68: time frequency analysis means, 82: External noise calculation means, 84: external noise display means, 86: external noise analysis means.

Claims (1)

A heart sound meter comprising a heart sound sensor for detecting a heart sound generated from the heart and outputting a heart sound signal representing the heart sound, and measuring a heart sound waveform represented by the heart sound signal,
From the heart sound signal, a waveform extracting means for extracting a heart sound waveform of a predetermined section generated every cycle as an extracted waveform;
Phase adjusting means for adjusting the phases of the extracted waveforms so that the extracted waveforms extracted by the waveform extracting means match each other;
Adding means for adding the extracted waveforms whose phases are matched by the phase matching means;
Representative extracted waveform determining means for determining a representative extracted waveform based on the extracted waveform calculated by the adding means;
An electrocardiograph comprising: an external noise calculating unit that calculates an external noise waveform from a difference between the extracted waveform extracted by the waveform extracting unit and the representative extracted waveform.

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