JP7811466B2 - Heart disease testing equipment - Google Patents

Description

The present invention relates to a cardiac disease testing device and cardiac disease testing method that can distinguish between aortic valve stenosis and mitral valve regurgitation.

Aortic valve stenosis (AS) is a disease in which the aortic valve, one of the four valves in the heart, located between the left ventricle and the aorta, becomes difficult to open due to inflammation and hardening. The number of AS patients is on the rise as the population ages.

Mitral insufficiency (MI), also known as mitral regurgitation (MR), is a condition in which the mitral valve does not close properly during systole when the left ventricle contracts, causing some blood to flow back into the left atrium.

Naturally, it is desirable to detect and treat aortic stenosis and mitral regurgitation early.

Generally, doctors diagnose aortic stenosis and mitral regurgitation based on the patient's phonocardiogram and electrocardiogram. However, experience is required for doctors to perform cardiac auscultation accurately.

On the other hand, for example, Patent Document 1 discloses a diagnostic device that diagnoses heart valve disease by frequency analysis of phonocardiograms. It is believed that using such a diagnostic device would make it possible to identify heart valve disease even without a doctor with extensive experience in auscultation of heart sounds.

Special Publication No. 2007-508899

However, the diagnostic device disclosed in Patent Document 1 requires vector and matrix calculations in multidimensional space across all heart sounds, which increases the scale of calculations and is thought to result in a complex configuration. Another possible method is to perform frequency analysis of the phonocardiogram using a wavelet transform, but this method also has the disadvantage of increasing the scale of calculations.

The present invention was made in consideration of the above points, and provides a heart disease testing device and heart disease testing method that can distinguish between aortic valve stenosis and mitral valve regurgitation with a simple configuration.

One aspect of the cardiac disease examination device of the present invention is
a phonocardiogram acquisition unit for acquiring a phonocardiogram of the subject;
a systolic noise measuring unit that measures late systolic noise among systolic noises of the phonocardiogram;
a determination unit that determines whether the subject has aortic stenosis or mitral regurgitation based on the late systolic murmur;
Equipped with.

One embodiment of the cardiac disease examination method of the present invention comprises:
obtaining a phonocardiogram of the subject;
measuring late systolic murmurs from the phonocardiogram;
determining whether the subject has aortic stenosis or mitral regurgitation based on the late systolic murmur;
Includes.

The present invention makes it possible to distinguish between aortic valve stenosis and mitral valve regurgitation using a simple configuration.

FIG. 1 is a diagram showing the overall configuration of a blood pressure pulse wave inspection device according to an embodiment. A block diagram showing the main configuration of a cardiac disease examination device according to an embodiment. Diagram explaining systolic murmur 1 is a waveform diagram illustrating the operation of an embodiment of the present invention; 5A and 5B are diagrams showing examples of systolic murmurs, in which FIG. 5A shows a systolic murmur in a case where the patient is not suffering from aortic stenosis or mitral regurgitation, FIG. 5B shows a systolic murmur caused by aortic stenosis, and FIG. 5C shows a systolic murmur caused by mitral regurgitation. 1 is a flowchart illustrating a cardiac disease examination method performed by an embodiment.

Embodiments of the present invention will be described in detail below with reference to the drawings.

<1> Overall Configuration of Blood Pressure Pulse Wave Examination Apparatus FIG. 1 is a diagram showing the overall configuration of a blood pressure pulse wave examination apparatus 1 to which the heart disease examination apparatus and heart disease examination method of the present invention are applied.

In FIG. 1, the main body 1a of the blood pressure pulse wave inspection device 1 is provided with an arithmetic processing unit 10, an input unit 70, a display unit 80, a printing unit 91, a memory unit 92, an audio output unit 93, a blood pressure pulse wave measuring unit 30, a heart sound measuring unit 40, an electrocardiogram measuring unit 50, and a pulse wave measuring unit 60.

The blood pressure pulse wave measurement unit 30 has an upper arm measurement control unit 31 and a lower limb measurement control unit 32. The upper arm measurement control unit 31 is connected to a right upper arm cuff 21R and a left upper arm cuff 21L via hoses 21h, respectively, and the lower limb measurement control unit 32 is connected to a right ankle cuff 22R and a left ankle cuff 22L via hoses 22h, respectively.

A heart sound microphone 23 is connected to the heart sound measurement unit 40. A limb electrocardiogram electrode unit 24a and a chest electrocardiogram electrode unit 24b are connected to the electrocardiogram measurement unit 50. Amorphous pulse wave sensors 25a and 25b are connected to the pulse wave measurement unit 60.

The calculation processing unit 10 is a computer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), various interfaces, etc. The calculation control unit 10 performs calculation processing for determining heart disease, as described below, by executing a control program stored in the ROM with the CPU. In other words, the calculation control unit 10 has the function of determining heart disease.

The calculation processing unit 10 also controls the upper arm measurement control unit 31, the lower limb measurement control unit 32, the heart sound measurement unit 40, the electrocardiogram measurement unit 50, and the pulse wave measurement unit 60 (hereinafter referred to as "each biological information measurement unit"), which measure various biological information.

The calculation processing unit 10 also receives biometric information supplied from each biometric information measurement unit. Then, if the received biometric information needs to be displayed on a screen, it edits or converts it into display data and outputs it to the display unit 80, or if it needs to be printed on report paper, it edits or converts it into print data and outputs it to the print unit 91. The calculation processing unit 10 also stores the received biometric information in the memory unit 92 and reads out the stored biometric information as appropriate.

The calculation processing unit 10 also performs waveform analysis of the biological information received from each biological information measurement unit. Waveform analysis involves detecting characteristic parts (dividing points) in the waveform. Examples of characteristic parts include the start of the second heart sound, the rising edge of the pulse wave at the upper arm, the rising edge of the pulse wave at the ankle, and the notch part of the pulse wave at the upper arm.

The calculation processing unit 10 calculates the degree of arteriosclerosis based on the analysis results and the values indicated by the received biological information (e.g., blood pressure).

The calculation processing unit 10 also receives inputs and instructions from the user via the input unit 70, and, in accordance with the received information, performs settings related to the functions of each biometric information measurement unit, display unit 80, printing unit 91, memory unit 92, and audio output unit 93, and controls the start and stop of each operation.

The display unit 80 is a display device having a display screen such as an LCD (Liquid Crystal Display), and displays on the screen the biometric information, analysis results, arteriosclerosis level, etc. input as display data from the calculation processing unit 10.

The printing unit 91 mainly comprises a paper feed mechanism, a print head, etc., and prints on paper the biometric information, analysis results, and arteriosclerosis level input as printing data from the processing unit 10.

The memory unit 92 is composed of a hard disk drive, a writable optical disk drive, non-volatile memory, etc., and is capable of storing information from the calculation processing unit 10. The memory unit 92 also records biometric information measured by each biometric information measurement unit, namely, electrocardiogram, pulse wave, and heart sounds.

The audio output unit 93 has a speaker as its main component, and outputs guidance voices or notification sounds, etc., in accordance with the guidance data or notification sound output instruction signal input from the calculation processing unit 10.

The input unit 70 is composed of a keyboard, mouse, buttons, touch panel, etc., and accepts inputs and instructions from the user and sends them to the calculation processing unit 10.

The pulse wave measurement unit 60 supplies the subject's pulse wave signals detected by amorphous pulse wave sensors 25a, 25b, which are appropriately attached to the subject, to the calculation processing unit 10. This allows the pulse wave to be measured and analyzed. One of the amorphous pulse wave sensors 25a, 25b is attached, for example, to the subject's carotid artery, and the other is attached, for example, to the subject's femoral artery or knee.

In this embodiment, the blood pressure pulse wave measuring unit 30 comprises an upper limb measurement control unit 31 and a lower limb measurement control unit 32 that are provided separately, but the upper limb measurement control unit 31 and the lower limb measurement control unit 32 may also be integrated. Known technology can be used to measure blood pressure pulse waves using the blood pressure pulse wave measuring unit 30 that has the upper limb measurement control unit 31 and the lower limb measurement control unit 32, so a detailed explanation will be omitted here.

The electrocardiogram measurement unit 50 supplies the electrocardiogram signals detected by the four limb electrocardiogram electrodes 24a and chest electrocardiogram electrodes 24b attached to the subject to the calculation processing unit 10. This allows electrocardiogram measurement and analysis. The four limb electrocardiogram electrodes 24a typically consist of four electrocardiogram electrodes attached to the right wrist, left wrist, right ankle, and left ankle, respectively. The electrocardiogram electrodes for both ankles are preferably configured so that their attachment to both ankles is not obstructed by the right ankle cuff 22R and left ankle cuff 22L. The chest electrocardiogram electrode unit 25b typically consists of six electrocardiogram electrodes attached to six locations on the chest.

The heart sound measurement unit 40 supplies the heart sound signal detected by the heart sound microphone 23 attached to the subject to the calculation processing unit 10. This allows the heart sounds to be measured and analyzed.

<2> Diagnosis of Heart Disease According to This Embodiment As described above, the arithmetic processing unit 10 of this embodiment has the function of diagnosing heart disease. In practice, it has the configuration shown in Fig. 2, and diagnosing heart disease is performed using this configuration. The arithmetic processing unit 10 has a systolic noise measurement unit 11, a measurement interval setting unit 12, and a determination unit 13.

The systolic noise measurement unit 11 measures the late systolic noise from the systolic noise of the phonocardiogram. The measurement interval setting unit 12 sets the late systolic interval based on the electrocardiogram and outputs information about the set interval to the systolic noise measurement unit 11. The determination unit 13 determines whether the subject has aortic stenosis or mitral regurgitation based on the late systolic noise determined by the systolic noise measurement unit 11.

Figure 3 is a diagram used to explain systolic murmurs. Figure 3 shows an electrocardiogram, heart sounds, and heart murmurs. The peak of the R wave in the electrocardiogram and the start of the first heart sound are roughly the same, and the end of the T wave in the electrocardiogram and the start of the second heart sound are roughly the same. Systolic period (ventricular systole) can be described as the period from the peak of the R wave to the end of the T wave, or the period from the end of the first sound to the start of the second sound. Systolic murmurs are noises contained in heart sounds during systole (ventricular systole). In other words, systolic murmurs are heart sounds during systole (ventricular systole) excluding the first and second sounds.

Returning to Figure 2, the configuration of the calculation processing unit 10 will be further explained.

The systolic noise measurement unit 11 includes an M-Filter 11a, an envelope creation unit 11b, and an area calculation unit 11c.

The heart sounds obtained by the heart sound measurement unit 40 are input to M-Filter 11a. M-Filter 11a extracts specific frequency components from the heart sounds. Specifically, M-Filter 11a extracts and outputs frequencies affected by aortic stenosis and mitral regurgitation. For example, M-Filter 11a extracts frequency components above 160 Hz.

The envelope creation unit 11b creates an envelope of the signal after filtering. Specifically, the envelope creation unit 11b creates the envelope by, for example, finding a statistical approximation curve using a smoothing calculation such as RMS (Root Mean Square). Note that the method by which the envelope creation unit 11b creates the envelope is not limited to this. For example, the envelope may be created using a Hilbert transform. Various conventionally known methods can be used to create the envelope.

The area calculation unit 11c calculates the area of the late systole surrounded by the envelope and the baseline. Specifically, the area calculation unit 11c inputs the envelope created by the envelope creation unit 11b and the late systole section from the measurement section setting unit 12. The area calculation unit 11c then calculates the area surrounded by the envelope for the late systole section set by the measurement section setting unit 12.

The determination unit 13 makes a determination based on the area in the late systole calculated by the area calculation unit 11c. Specifically, if the area is equal to or greater than a first threshold, the area calculation unit 11c determines that the subject has aortic stenosis, and if the area is less than the first threshold and equal to or greater than a second threshold (where 0 < second threshold < first threshold), the area calculation unit 11c determines that the subject has mitral regurgitation.

The operation of this embodiment will be explained in more detail using Figure 4.

The waveform in Figure 4 shows the systolic murmur after passing through the M-Filter 11a. The envelope in the figure shows the envelope output from the envelope creation unit 11b.

The measurement interval setting unit 12 sets the measurement interval based on the second sound of the phonocardiogram. Specifically, the measurement interval setting unit 12 first detects the start of the second sound based on the end of the T wave in the electrocardiogram. Next, it sets a predetermined interval from the start of the second sound in the past as the measurement interval. In this embodiment, the measurement interval setting unit 12 sets the interval between a point, for example, 50 ms before the start of the second sound, and a point, for example, another 50 ms before that point as the measurement interval.

The measurement interval set by the measurement interval setting unit 12 is not limited to this. For example, the measurement interval may simply be set to the latter half of the systole divided into two equal parts, or the measurement interval may be set to the latter half of the systole divided into three equal parts. However, setting the measurement interval at a position a predetermined distance away from the second heart sound, as in this embodiment, has the advantage of being less susceptible to the influence of the second heart sound.

Incidentally, because phonocardiograms contain a lot of noise, detecting the second sound directly from a phonocardiogram may result in a decrease in detection accuracy. Therefore, the measurement interval setting unit 12 detects the position of the second sound based on the position of the T wave.

Figure 5 shows examples of systolic murmurs. Figure 5A shows systolic murmurs in a patient with neither aortic stenosis nor mitral regurgitation, with almost no systolic murmur. Figure 5B shows systolic murmurs in aortic stenosis, with the noise level increasing in the latter half of systole. Figure 5C shows systolic murmurs in mitral regurgitation, with a nearly constant noise level throughout the entire systole.

The inventors of the present invention realized that the noise level in the latter half of systole differs significantly between aortic stenosis and mitral regurgitation. In particular, they noticed that the noise level in aortic stenosis is significantly higher than the noise level in mitral regurgitation in the latter half of systole.

Incidentally, when looking at the entire systolic phase, there is a possibility that the noise area of aortic stenosis and the noise area of mitral regurgitation will be similar. Taking this into consideration, the present invention distinguishes between aortic stenosis and mitral regurgitation based on the noise area in the late systolic phase, where the noise areas differ greatly between aortic stenosis and mitral regurgitation.

Figure 6 is a flowchart illustrating a cardiac disease testing method executed by the processing unit 10 according to an embodiment.

First, in step S11, the late systolic noise is measured by the systolic noise measurement unit 11. In this embodiment, the area S is measured.

Next, the determination unit 13 performs a threshold determination process for the area S. If the determination unit 13 determines in step S12 that the area S is equal to or greater than threshold 1, the process proceeds to step S13, where it determines that the subject has aortic stenosis. If the determination unit 13 determines in step S14 that the area S is less than threshold 1 and equal to or greater than threshold 2 (where 0 < threshold 2 < threshold 1), the process proceeds to step S15, where it determines that the subject has mitral regurgitation. If the determination unit 13 obtains a negative result in step S14, the process proceeds to step S16, where it determines that the subject does not have aortic stenosis or mitral regurgitation.

<3> Summary As described above, according to this embodiment, a phonocardiogram acquisition unit (heart sound measurement unit 40) that acquires a phonocardiogram of the subject, a systolic noise measurement unit 11 that measures late systolic noise from the systolic noise of the phonocardiogram, and a determination unit 13 that determines whether the subject has aortic stenosis or mitral regurgitation based on the late systolic noise can be provided, thereby realizing a heart disease examination device and heart disease examination method that can distinguish between aortic stenosis and mitral regurgitation with a simple configuration.

In other words, since calculations only need to be performed over a limited range, such as the late systole, the amount of calculation required is small. Furthermore, since this can be achieved through low-computational processes such as extracting specific frequencies, creating envelopes, and calculating areas, the amount of calculation required is also small. As a result, it is possible to distinguish between aortic valve stenosis and mitral valve regurgitation using a simple configuration.

The above-described embodiments are merely examples of specific ways of implementing the present invention, and should not be construed as limiting the technical scope of the present invention. In other words, the present invention can be implemented in various forms without departing from its gist or main characteristics.

In the above embodiment, the measurement interval setting unit 12 sets the late systolic interval based on an electrocardiogram. However, the present invention is not limited to this. The measurement interval setting unit 12 may set the late systolic interval based on a pulse wave diagram. In other words, because the measurement interval setting unit 12 sets the measurement interval based on the second heart sound, various methods capable of detecting the second heart sound can be applied. Therefore, conventional methods for detecting the second heart sound based on a pulse wave diagram can also be applied. In this case, it is sufficient to provide a pulse wave diagram acquisition unit (blood pressure pulse wave measurement unit 30) that acquires the subject's pulse wave diagram, and a measurement interval setting unit 12 that sets the late systolic interval in which the systolic noise measurement unit 11 measures noise based on the pulse wave diagram. Furthermore, the second heart sound can be detected not only using an electrocardiogram or a pulse wave diagram, but also using other methods such as filtering heart sounds or frequency analysis.

In the above-described embodiment, aortic stenosis and mitral regurgitation are diagnosed based on the area of late systolic noise. However, aortic stenosis and mitral regurgitation may also be diagnosed based on factors other than area, such as the amplitude or power of late systolic noise, or the shape of the noise on the amplitude-time plane within the late systolic measurement interval.

Furthermore, in the above-described embodiment, aortic stenosis and mitral regurgitation are diagnosed by threshold-based area determination, but this is not limited to this. For example, aortic stenosis and mitral regurgitation may be determined based on the ratio of the area of systolic murmurs in the late systole to the area of systolic murmurs throughout the systole. In other words, as can be seen from Figures 5B and 5C, the ratio should be greater in aortic stenosis than in mitral regurgitation, and therefore aortic stenosis and mitral regurgitation can be determined by threshold-based determination of this ratio.

In the above-described embodiment, the cardiac disease testing device and cardiac disease testing method of the present invention are described as being embodied in a blood pressure pulse wave testing device 1, but the cardiac disease testing device and cardiac disease testing method of the present invention are not limited to this and may also be embodied in a device (such as a personal computer) separate from the blood pressure pulse wave testing device.

In essence, the cardiac disease examination device of the present invention is equipped with a phonocardiogram acquisition unit that acquires a phonocardiogram of the subject, a systolic noise measurement unit that measures the late systolic noise from the phonocardiogram, and a determination unit that determines whether the subject has aortic stenosis or mitral regurgitation based on the late systolic noise. Here, the phonocardiogram acquisition unit may be the phonocardiogram measurement unit 40 as in the above-described embodiment, but it may also be an input unit such as an interface that inputs heart sound information.

The present invention is widely applicable as a heart disease testing device and heart disease testing method for distinguishing between aortic valve stenosis and mitral valve regurgitation.

1 Blood pressure pulse wave inspection device 10 Processing unit 11 Systolic noise measurement unit 11a M-Filter
11b envelope creation unit 11c area calculation unit 12 measurement section setting unit 13 determination unit 40 heart sound measurement unit 50 electrocardiogram measurement unit

Claims (9)

a phonocardiogram acquisition unit for acquiring a phonocardiogram of the subject;
a systolic noise measuring unit that measures late systolic noise among systolic noises of the phonocardiogram;
a determination unit that determines whether the subject has aortic stenosis or mitral regurgitation based on the area of the late systolic murmur;
Equipped with
The determination unit
If the area is equal to or greater than a first threshold, the subject is determined to have aortic valve stenosis;
If the area is less than the first threshold and is equal to or greater than a second threshold (where 0<second threshold<first threshold), the subject is determined to have mitral regurgitation.
Cardiac disease testing equipment. a phonocardiogram acquisition unit for acquiring a phonocardiogram of the subject;
a systolic noise measuring unit that measures late systolic noise among systolic noises of the phonocardiogram;
a determination unit that determines whether the subject has aortic stenosis or mitral regurgitation based on the area of the late systolic murmur;
A cardiac disease examination device comprising: an electrocardiogram acquisition unit for acquiring an electrocardiogram of the subject;
a measurement interval setting unit that sets the late systolic interval in which the systolic noise measuring unit measures noise based on the electrocardiogram;
Further provided with
3. The cardiac disease examination apparatus according to claim 1 or 2 . a pulse wave diagram acquiring unit for acquiring a pulse wave diagram of the subject;
a measurement interval setting unit that sets the late systolic interval in which the systolic noise measuring unit measures noise based on the sphygmogram;
Further provided with
3. The cardiac disease examination apparatus according to claim 1 or 2 . The late systolic period is set based on the second sound of the phonocardiogram.
The cardiac disease examination apparatus according to any one of claims 1 to 4 . The late systolic section is a section that is a predetermined interval away from the start of the second sound of the phonocardiogram.
The cardiac disease examination device according to claim 5 . the systolic noise measuring unit includes a filter that extracts a predetermined frequency component from the phonocardiogram, an envelope creating unit that creates an envelope of the filtered signal, and an area calculating unit that calculates the area of the late systole surrounded by the envelope;
the determination unit makes the determination based on the area in the late systole calculated by the area calculation unit.
The cardiac disease examination apparatus according to any one of claims 1 to 6 . The determination unit
If the area is equal to or greater than a first threshold, the subject is determined to have aortic valve stenosis;
If the area is less than the first threshold and is equal to or greater than a second threshold (where 0<second threshold<first threshold), the subject is determined to have mitral regurgitation.
The cardiac disease examination apparatus according to claim 2 or 7. The determination unit
A determination is made as to whether the subject has aortic stenosis or mitral regurgitation based on a ratio of an area of the systolic murmur in the late systole to an area of the systolic murmur throughout the systole.
The cardiac disease examination apparatus according to claim 2 or 7.