JPH0315441A - Cardiac sound meter - Google Patents

Abstract

PURPOSE:To obtain a cardiac sound meter, in which a diagnosis can be more objectively performed through improved diagnostic accuracy of the cardiac sound meter, by mounting a plurality of cardiac sound sensors on the breast, calculating intensity distribution of a cardiac sound by a plurality of cardiac sound signals simultaneously obtained from the sensors and diagnosing a heart disease from a feature of the intensity distribution. CONSTITUTION:A detection signal from a cardiac sound sensor 1i, arranged in each position, is amplified to a predetermined voltage value respectively by an amplifier 2i, thereafter a low-pitched sound part is attenuated by a high pass filter 3i to obtain the flat frequency characteristic, converted into a digital signal by an A/D converter 4i and given to a time division circuit 7. In the digital signal, contraction and expansion phases are set based on a time division signal from a waveform recognizing circuit 6 in the time division circuit 7, further each magnetism is equally divided in a plurality of sections. The time division digital signal is given to a band pass filter circuit 8 and divided into a signal of each component of low, intermediate and high frequency in each divided section. In an intensity arithmetic circuit 9, cardiac sound intensity of division section is calculated from a time series data in each frequency and each division timing, and an arithmetic result can be utilized for diagnosis by displaying the result on a display medium of CRT.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phonocardiograph used for diagnosing heart disease.

[Conventional technology]

Heart sounds are the opening and closing of the atrioventricular valves and semilunar valves and the sounds from the atria to the ventricles when the heart repeatedly contracts and expands to pump blood to each tissue.
This is the sound caused by blood flow to large blood vessels.

By the way, various heart diseases such as heart valve disease and aneurysm,
As each diseased area deforms and changes in quality, a unique sound (heart murmur) is generated by blood flow. For this reason, doctors have traditionally listened to these heart sounds and used them for diagnosis, such as checking for the presence of heart disease and identifying the name of the disease. However, diagnosing heart disease based on heart sounds is relatively difficult for doctors other than heart specialists.

For this reason, a device called a phonocardiograph has been devised to facilitate diagnosis. This device detects heart sounds using a heart sound sensor such as a microphone attached to a predetermined position on the chest, converts it into an electrical signal, and records it on recording paper as a time waveform (
Phonocardiogram) was developed for the purpose of diagnosis based on the characteristics of its waveform, but it is known that it is difficult to diagnose heart disease from the waveform alone, and currently it is difficult to diagnose heart disease from the waveform alone. The situation is such that it is merely being used as Hassoku data to provide objectivity.

The characteristics of heart sounds will be explained below using the attached phonocardiogram. 7th
The figure schematically illustrates, from the top, an electrocardiogram, a normal phonocardiogram, and phonocardiograms A to G corresponding to various heart diseases, each regarding heart sounds at the apex of the heart.

In Figure 7, the I sound is the sound that occurs when the mitral valve between the left atrium and left ventricle of the heart and the tricuspid valve between the right atrium and right ventricle open and close, and the ■ sound is the sound that occurs between the left ventricle and the aorta. It is said to be the sound of the aortic valve, the pulmonary artery valve between the right ventricle and the pulmonary artery opening and closing. The I sound and the ■ sound can each be captured as specific peak waveforms in a phonocardiogram. The period between the I sound and the ■ sound corresponds to the systolic period of the ventricle, and the period between the H sound and the next section of the ■ sound corresponds to the ventricular diastole period. The waveform that occurs during these periods is the heart murmur, and the former The latter is called a systolic murmur, and the latter is called a diastolic murmur.

As is clear from diagrams A-G in Figure 7, when does the heart murmur occur and how does its size change (gradually increasing, decreasing, gradually increasing, constant, etc.)? The type of disease can be determined to some extent by the characteristics of the heart murmur, such as whether the high-pitched sound component is strong or the low-pitched sound component is strong.

Next, actual waveforms when heart sounds are recorded for each frequency band are illustrated in FIGS. 8 and 9. That is, FIG. 8 shows, as an example of a systolic murmur, a phonocardiogram of a patient with mitral regurgitation, using a high-pass filter that cuts low frequencies and emphasizes high frequencies, a low-pass filter that emphasizes low frequencies, and a Wu filter that is intermediate between the above. Recordings were made using a medium filter and an ear-like filter that simulated the human auditory characteristics, dividing them into four types of frequency bands, namely H, L, M, and E bands in the above order. The patient has the characteristics of Figure 7C, with a continuous heart murmur.

Similarly, FIG. 9 shows an example of a diastolic murmur, in which heart sounds due to mitral stenosis at the apex of the heart are recorded separately for each band. This waveform shows the characteristic of FIG. 7E, which is a progressively increasing heart murmur during diastole.

As mentioned above, current phonocardiograms are mainly used as hack data for diagnosis, but as is clear from the phonocardiograms shown above, the characteristics of heart sounds differ depending on each heart disease. Utilizing this, attempts are being made to use the phonocardiograph for direct diagnosis.

For example, the invention disclosed in Japanese Patent Publication No. 56-39220 is a waveform synthesizer that installs a plurality of heart sound sensors in the chest, detects the envelope of the heart sound, and extracts the maximum value of each instantaneous value of the heart sound signal based on the envelope. A heart sound screening device equipped with a discriminator for each waveform such as , ■sound, and ■sound, a comparator that compares each waveform with a reference value, and a discrimination display that distinguishes between a normal person and a person who requires detailed examination based on the comparison result. It is.

[Problems to be Solved by the Invention] By the way, the heart sound screening device extracts the signal giving the maximum value from the heart sound signals of a plurality of heart sound sensors, and compares this signal with a reference value to improve the accuracy of diagnosis. Therefore, there is a problem in that the heart sound information output from a plurality of heart sound sensors is not fully utilized, and further improvements are recognized to be necessary in order to increase diagnostic accuracy.

The present invention includes a plurality of heart sound sensors attached to the chest, a plurality of heart sound signals obtained simultaneously from these sensors, calculating the intensity distribution of the heart sound, and diagnosing heart disease from the characteristics of the intensity distribution. The purpose of the present invention is to provide a phonocardiograph that improves the diagnostic accuracy of a single phonocardiograph and enables more objective diagnosis.

[Means to solve the problem]

The structure of the phonocardiograph of the present invention to achieve the above objects,
A heart sound detection unit selected from a plurality of heart sound sensors attached to cover a predetermined region of the chest of the subject, a means for filtering the heart sound signals provided from each of the heart sound sensors into a plurality of frequency bands, and a means for filtering one cycle of the heart sound signal. ■Sound・■It has means for dividing the sound into a plurality of periods based on the sound, and for each frequency band,
Further, the present invention is characterized in that it includes a calculation unit that calculates the heart sound intensity distribution on the predetermined area for each of the divided intervals.

A conventionally used sensor can be used as the unit heart sound sensor used in the present invention.

The unit sensors are placed at multiple locations on the chest.

Although the number is not particularly limited, they are used by being closely attached to several to several dozen intercostal spaces using double-sided adhesive tape or the like as determined by the doctor to be necessary for diagnosis.

The phonocardiograph of the present invention divides one cycle of heart sounds into a plurality of periods for each frequency band, and calculates the heart murmur intensity distribution for each divided period. At that time, the method of dividing into multiple periods based on the I sound and ■ sound is to separate the I sound and the ■ sound from the heart waveform, extract the systolic murmur and diastolic murmur, and then divide the murmur period into each period. , this can be done by equally dividing into multiple periods, for example, each noise period.

The heart murmur separation described above is for calculating accurate heart murmur intensity, and as mentioned above, heart sounds that occur even in a normal heart, such as the I sound and the ■ sound, are excluded for any measurement site. to be done.

The separation occurs due to expansion, contraction, etc. of the heart.
This is done by capturing characteristic sounds such as sounds and ■ sounds and determining the timing of division. ■Sounds and ■sound intervals can be determined from the cardiac waveform alone, but usually characteristic parts of the electrocardiogram waveforms measured at the same time are detected, and based on these, one sound, ■sound area, systole and diastole are determined. and set. Then, each karima is divided into a predetermined number of sections.

1 work Kawa] The phonocardiograph of the present invention filters heart sounds into multiple frequency bands,
Furthermore, by dividing one heart sound cycle into a plurality of periods based on the I sound and the ■ sound, the frequency range 41} and 1! J1
The heart sound intensity distribution is calculated for each interval. Therefore, the characteristics of heart sounds caused by cardiac abnormalities can be highlighted by the intensity distribution on the chest wall, making it possible to make highly accurate diagnoses.

[Example] An example will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a Bronnoch diagram showing an outline of the phonocardiograph of this embodiment, and FIG. 2 is a diagram showing the position where the heart sound sensor used in FIG. 1 is attached to the chest of the subject.

In this example, a heart sound sensor 1+ (i-1 to 30, hereinafter the same) consisting of an 8 mm diameter cylindrical acceleration pick amplifier is used, and as shown in FIG. 6 rows in the horizontal direction, 7 points on the longitudinal midclavicular line A, 3 points on the anterior axillary line B, and for the remaining 4 rows, 5 points each are placed parallel to these as shown in the figure. A total of 30 pieces were used to construct the heart sound detection unit. The heart sound sensor'ri'1 is,
It was attached tightly to the chest using double-sided adhesive tape.

In addition, at the stage of practical application of the present invention, it is considered possible to obtain the heart sound intensity distribution necessary for diagnosis even if the number of measurement points is reduced from this embodiment depending on the purpose of measurement.

In addition, a second
An electrocardiograph (not shown) was placed on the subject's right wrist (also not shown). The left ankle was attached using lead ①.

In FIG. 1, the detection signals from the 30 heart sound sensors 1 arranged at each position are each amplified to a predetermined voltage value by an amplifier 2, and then a high-pass filter 3 attenuates the bass part. This signal has a flat frequency characteristic, is converted into a digital signal by the A/D converter 4, and is provided to the time division circuit 7.

The digital signal is sent to a waveform recognition circuit 6 by a time division circuit 7.
The systole and diastole are set based on the time-shared signal from
Further, each magnetic field is equally divided into a plurality of sections.

The time-division signal was obtained by the following procedure. That is, the electrocardiographic signal from the electrocardiographic sensor 5 (FIG. 1) is amplified by the amplifier 2c in the same manner as the heart sound signal, and then converted into a digital signal by the A/D converter 4c, which is then provided to the waveform recognition circuit 6. .

In the waveform recognition circuit 6, the R wave of the electrocardiogram is recognized from the signal, and the I sound and L sound regions are respectively identified using the peak of the R wave as a reference, thereby obtaining a time-division signal.

9 1 0 The time-divided digital signal is given to the bandpass filter circuit 8 and is divided into signals of low frequency, medium frequency, and high frequency components for each division section.

In this embodiment, as shown in FIG. 3, using the time-division signal, the remaining heart murmur portion after removing the I and ■ sounds from the waveform of one heart sound section is divided into systolic and diastolic periods for each frequency band. was equally divided into three periods, and the heart murmur signals of periods 1 to 6 were obtained as a whole, as shown in FIG.

The intensity calculation circuit 9 calculates the heart sound intensity in the divided section from the time-series data for each frequency and time-divided period. The calculation results of the calculation circuit 1 and 9 are displayed on a display medium such as a CRT in the form of a color-coded diagram or an isointensity diagram, numerically displayed, or pattern-matched with an already registered intensity distribution pattern. This can be used for diagnosis.

In this embodiment, as one example of processing the calculation results of the calculation circuit 9, the distribution of the heart murmur intensity is outputted as a contour map on a CRT (not shown) for each period and each frequency. Examples of the results are shown in FIGS. 4 to 6.

Figure 4 shows the heart murmur distribution in the low frequency band and early diastole (first stage) of mitral regurgitation, and it can be seen that the strongest point is at the apex of the heart. FIG. 5 is a heart murmur distribution map in the middle frequency band and mid-systole of ventricular septal defect (D in FIG. 7). Furthermore, Fig. 6 is a heart murmur distribution map in the intermediate frequency band and mid-systole of aortic valve stenosis (Fig. 7B), in which the positions of the strongest points are clearly different even in the same frequency band and at the same time. Therefore, it is understood that by correlating the distribution characteristics of the heart murmur intensity with the names of heart diseases and categorizing them, it becomes possible to diagnose heart diseases more clearly and objectively than before.

[Effect of the invention] As explained above, the phonocardiograph of the present invention can detect one heart sound and ■
For the systolic period between the sound and the diastolic period between the sound and the sound of the next heart sound cycle, the heart sound intensity is calculated by dividing it into multiple predetermined frequency bands and time division intervals, and the distribution of the intensity is calculated. 11 12 4. Since the configuration is as follows, it is possible to capture the characteristics of heart disease that could not be detected by conventional heart sounds, and to make it useful for diagnosis.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing the outline of the structure of the phonocardiograph of the present invention according to an embodiment, FIG. 2 is a diagram showing the mounting position of the heart sound sensor used in FIG. 1, and FIG. Graphs showing time-divided conditions, Figures 4 to 6 are isointensity diagrams of heart sound intensity distribution, and Figure 7 is a typical electrocardiogram, a phonocardiogram of a normal heart, and various heart diseases. FIGS. 8 to 9 are graphs each schematically showing a phonocardiogram, and each of FIGS. 8 and 9 is a diagram showing how heart sounds with heart murmurs are filtered into four stages from low frequency to high frequency. DESCRIPTION OF SYMBOLS 1... Unit heart sound sensor, 2... Amplifier, 3... High pass filter, 4... A/D converter, 5... Electrocardiogram sensor, 6... Waveform recognition circuit, 7...・Time division circuit,
8...Band filter retreat path, 9...Heart sound intensity calculation circuit. 13 ・j Armpit

Claims (1)

[Claims] A heart sound detecting unit consisting of a plurality of heart sound sensors attached to cover a predetermined area of the chest of the subject, means for filtering the heart sound signals provided from each of the heart sound sensors into a plurality of frequency bands, and a means for filtering one cycle of the heart sound signal. A phonocardiograph having means for dividing into a plurality of periods based on sound and II sound, and comprising a calculation unit for calculating a heart sound intensity distribution on the predetermined region for each of the frequency bands and for each of the divided periods.