JPWO2020071480A1 - Pulse wave velocity measuring device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a pulse wave velocity on one path including an aorta in the same blood flow direction with a simple configuration and a non-invasive method.
A piezoelectric vibration sensor 10A is a core bullet wave sensor, and a piezoelectric vibration sensor 10B is a pulse wave sensor. A cardiac bullet wave is one in which the vibration of heart valve operation is transmitted through the skeleton and skeletal muscle as a medium. Can be done. Then, since the time when the pulse wave departed from the heart can be known from the cardiac bullet wave, the pulse wave velocity can be obtained from the arrival time of the pulse wave at the measurement site and the distance from the heart to the measurement site. Can be done.
[Selection diagram] Fig. 1

Description

The present invention relates to a pulse wave velocity measuring device and a method thereof for measuring and analyzing a pulse wave velocity (PWV), which is a change in blood pressure and volume in the vascular system accompanying the beating of the heart.

The pulse wave velocity is the rate at which the pulse wave generated by the beating of the heart propagates toward the periphery, and is known to be higher in patients with diseases such as hypertension, diabetes, and cerebral infarction. Atherosclerotic lesions are formed primarily in the aorta and extend to peripheral arterial sites such as the carotid and femoral arteries. Since arteriosclerosis is a risk factor for serious diseases such as ischemic heart disease, cerebrovascular accident, and aortic aneurysm, it is important to diagnose it early. The pulse wave velocity is attracting attention as an index.

FIG. 10 shows a method for measuring the pulse wave velocity in principle. The pulse waves WA and WB at the proximal point PA and the distal point PB of the arterial BV are measured or measured, respectively, and their rises. Find the time difference T. On the other hand, assuming that the arterial length between the proximal point PA and the distal point PB is L, the pulse wave velocity PWV can be obtained by L / T.

Ideally, the pulse wave velocity of the aorta, where atherosclerotic lesions are prominent, should be measured, but it is difficult to measure non-invasively and easily with current medical science. Therefore, a method has been devised in which pulse waves are detected non-invasively in peripheral arteries and the pulse wave velocity in arteries including the aorta and peripheral arteries is measured. As a specific example of such a pulse wave velocity, for example, the carotid-femoral pulse wave velocity cfPWV described after p121 of "Guidelines for non-invasive evaluation method of vascular function" of the following non-patent document. There is a pulse wave velocity measurement technology including the aorta such as (carotid-femoral PWV) and upper arm-ankle pulse wave velocity baPWV (brachial-ankle PWV), and early detection of serious cardiovascular diseases such as aortic dissection. Due to the need for, it has become widespread in the medical field of cardiovascular system. For example, in the following patent documents, _{the brachial pulse wave velocity baPWV is calculated based on the ankle pulse wave WL L} , and the lower limb upper limb blood pressure index (ABI) is used to diagnose the stenosis of the lower limb artery. ) The measuring device is disclosed.

Guidelines for Diagnosis and Treatment of Cardiovascular Diseases (2011-2012 Joint Research Group Report) P113-P145 "Guidelines for Non-Invasive Evaluation of Vascular Function"

JP-A-2002-272688

However, when the blood flow from the heart uses the arrival time difference of the pulse wave on two paths with different blood flow directions instead of the arrival time difference of the pulse wave on one path in one direction, the pulse wave depends on the vascular site. Considering that the propagation velocities differ greatly, it is difficult to say that it reflects the pulse wave velocity (aortic PWV; aoPWV) of the aorta.

In order to detect the time difference on one path from the heart such as the pulse wave velocity aoPWV of the aorta, it may be an invasive method such as inserting a catheter incorporating a pressure change detection sensor into two places in the aorta. Alternatively, only large-scale methods such as using an ultrasonic diagnostic device, MRI (magnetic resonance imaging), or CT (computed tomography) have been reported.

The present invention has focused on this point, and an object of the present invention is to accurately detect the pulse wave velocity on one pathway including the aorta with a simple structure and by a non-invasive method. Another purpose is to evaluate the possibility of arteriosclerosis using the detected pulse wave velocity.

The pulse wave velocity measuring device of the present invention is installed on the body surface side of a living body and has a first piezoelectric vibration sensor for detecting a heart bullet wave and a pulse wave propelling sensor installed on the body surface side of a living body to detect a pulse wave. The pulse wave velocity is calculated by using the second piezoelectric vibration sensor, the cardiac bullet wave obtained by the first piezoelectric vibration sensor, and the pulse wave obtained by the second piezoelectric vibration sensor. It is equipped with a calculation means.

According to one of the main forms, the first piezoelectric vibration sensor is installed on the body surface side of a skeleton or skeletal muscle that is connected without including joints. According to one of the other forms, the skeleton is one of the sternum, the spine, and the coccyx. According to still another form, the second piezoelectric vibration sensor is installed in a portion of the lower body of a living body where an artery is near the surface of the body. Alternatively, the second piezoelectric vibration sensor is installed on the thigh or the back of the knee.

According to still another embodiment, the calculation means includes the cardiac departure time of the pulse wave obtained from the cardiac bullet wave obtained by the first piezoelectric vibration sensor and the pulse obtained by the second piezoelectric vibration sensor. It is characterized in that the pulse wave velocity is calculated from the arrival time of the wave and the distance of the pulse wave propagation path from the heart to the measurement site of the second piezoelectric vibration sensor. Furthermore, it is characterized in that the aorta is included in the propagation path of the pulse wave detected by the second piezoelectric vibration sensor.

The arteriosclerosis evaluation device of the present invention is an arteriosclerosis evaluation device using the pulse wave velocity measuring device, and the pulse wave velocity of a living body measured by the pulse wave velocity measuring device and the arteriosclerosis obtained in advance. An evaluation means for evaluating that there is a possibility of arteriosclerotic lesions when the pulse wave velocity of the living body exceeds the normal pulse wave velocity by comparing with the pulse wave velocity in a normal living body in which the above is not occurring. It is characterized by having.

The pulse wave velocity measuring method of the present invention includes a step of installing a first piezoelectric vibration sensor for detecting a heart bullet wave and a second piezoelectric vibration sensor for detecting a pulse wave on the body surface side of a living body, respectively. The step of obtaining the heart departure time of the pulse wave from the cardiac bullet wave obtained by the first piezoelectric vibration sensor, the step of obtaining the arrival time from the pulse wave obtained by the second piezoelectric vibration sensor, and the above-mentioned A step of calculating the pulse wave velocity from the heart departure time of the pulse wave, the arrival time of the pulse wave, and the distance of the pulse wave propagation path from the heart to the measurement site of the second piezoelectric vibration sensor. It is characterized by including. The above and other objects, features and advantages of the present invention will be clarified from the following detailed description and accompanying drawings.

According to the present invention, the pulse wave and the cardiac bullet wave are measured from the output vibration waveform of the piezoelectric vibration sensor installed on the body surface side of the living body, and the pulse wave velocity is calculated by using them. Although it has a simple structure, it is possible to obtain a good pulse wave velocity of the aorta on one path in which blood flow is unidirectional by a non-invasive method, and it is also effective in evaluating arteriosclerosis.

It is a figure which shows the installation and the circuit structure of the piezoelectric vibration sensor in the Example of this invention. It is a figure which shows the specific example of the circuit structure of FIG. It is a figure which shows the measurement site of the pulse wave in the human in the said Example. It is a figure which shows the sensor part and the measuring device of pulse wave measurement using a rabbit. It is a figure which shows an example of the measurement waveform in the example of a rabbit. It is a figure which shows the measurement example of the pulse wave velocity by 2 paths and the pulse wave velocity of 1 path using a heart bullet wave in the rabbit example. It is a figure which shows the correlation of the pulse wave velocity including an aorta obtained from the catheter pressure sensor, and the pulse wave velocity obtained from the time difference between a piezoelectric vibration sensor and a catheter pressure sensor in the rabbit example. It is a figure which shows the correlation between the pulse wave velocity including an aorta obtained from the catheter pressure sensor in the rabbit example, and the pulse wave velocity obtained from the time difference of a piezoelectric vibration sensor. It is a graph which shows the pulse wave velocity measured using WHHLMI rabbit (genetic hyperlipidemia, coronary artery disease and arteriosclerosis) and normal rabbit. It is a figure which shows the principle of the measurement method of a pulse wave velocity.

Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

FIG. 1 shows the configuration of the pulse wave velocity measuring device according to the first embodiment of the present invention. As shown in the figure, in this embodiment, two piezoelectric vibration sensors are mounted on the body surface of the person to be measured. Of these, the piezoelectric vibration sensor 10A is fixed to the sternum by the belt 12A, and the piezoelectric vibration sensor 10B is fixed to the inguinal region by the belt 12B. The piezoelectric vibration sensor 10B may be fixed to the back of the knee, the instep, or the like. The sensor outputs of the piezoelectric vibration sensors 10A and 10B are input to the sensor modules 100A and 100B, respectively, and the output sides of these sensor modules 100A and 100B are connected to the waveform analysis device 300 via the output controllers 200A and 200B, respectively. ..

Among these, as the piezoelectric vibration sensors 10A and 10B, for example, the vibration waveform sensor disclosed in the international publication 2016/167202 pamphlet and the sensor module disclosed in the international publication 2017/187710 pamphlet are preferable examples. Is. The same piezoelectric vibration sensors 10A and 10B may be used, but those having characteristics corresponding to the vibration waveform to be detected may be used respectively. In this embodiment, the piezoelectric vibration sensor 10A is a core bullet wave sensor, and the piezoelectric vibration sensor 10B is a pulse wave sensor. Cardiac pulsation refers to minute vibrations of the human body caused by pulsation, which is a physical movement due to contraction and relaxation of the myocardium, and vibrations associated with the pulsation of the heart are transmitted through the skeleton and skeletal muscles as a medium. It has the advantage of being transmitted at a higher speed than pulse waves. The pulse wave propagating through the artery has a propagating velocity of about 5-20 m / s, whereas the cardiac bullet wave has a propagating velocity on the order of km / s, so that it is almost instantaneous when compared with the pulse wave. It can be considered to be transmitted. Then, since the time when the pulse wave departed from the heart can be known from the cardiac bullet wave, the pulse can be obtained from the arrival time of the pulse wave at the measurement site and the distance of the pulse wave propagation path from the heart to the measurement site. The wave velocity can be calculated.

In this embodiment, by utilizing the fact that the piezoelectric vibration sensors 10A and 10B can detect the heart bullet wave and the pulse wave, respectively, the peak of the heart bullet wave (the heart bullet wave signal generated when the heart valve closes) is detected near the thoracic bone. At the same time, pulse waves are detected near the femoral artery, and the time difference between the two is taken to measure the time difference of the route including the aorta.

As shown in FIG. 3, there are basically three peaks of the cardiac bullet wave, and it is considered that the vibration of the position SA where the vibration of blood occurs when the aortic valve and the pulmonary valve are closed is included in one of them. A piezoelectric vibration sensor 10A is installed at a site on the chest wall corresponding to the ascending aorta site SB 5 to 10 mm from this position. Further, the piezoelectric vibration sensor 10B is installed at a position close to the bifurcation SC of the abdominal aorta.

Next, an example of the sensor modules 100A and 100B, the output controllers 200A and 200B, and the waveform analysis device 300 will be shown in FIG. Of course, those disclosed in the above-mentioned pamphlet of International Publication No. 2016/167202 or Pamphlet of International Publication No. 2017/187710 may be used. Since the sensor modules 100A and 100B and the output controllers 200A and 200B have the same configuration in this embodiment, the sensor module 100A and the output controller 200A will be described. First, the sensor module 100A is provided with an instrumentation amplifier 102 on the input side, and an analog switch 104 is connected to the instrumentation amplifier 102. The analog switch 104 and the resistance array 105 are for controlling the drive of the instrumentation amplifier 102 based on the signal from the waveform analyzer 300, and are combined with the on / off of the analog switch 104 connected to the resistance array 105. This makes it possible to change the resistance value and change the amplification factor of the instrumentation amplifier 102. The output side of the instrumentation amplifier 102 is connected to the signal conversion unit 108 via a low-pass filter 106 for extracting low-frequency components, and an analog signal is converted into a digital signal and output.

Next, the output controller 200A is for outputting an input signal as a wireless signal such as BLE (Bluetooth (registered trademark) Low Energy), and is an input terminal 202 such as a 4-pin jack, a USB connector 204, a low pass filter 206, It is mainly composed of a communication module 210 such as a USB serial converter 208 and BLE. The power source is a lithium ion rechargeable battery 220 charged by the charge control circuit 216, and a discharge protection circuit 218 is provided. The communication module 210 is provided with a 3-axis acceleration sensor 214.

Of these, the input terminal 202 is used for signal input from the sensor module 100A. The low-pass filter 206 extracts the low-frequency component of the input signal and inputs it to the communication module 210. The USB connector 204 is used not only for signal output to an external device such as a PC but also for charging a power source. After the signal is converted by the USB serial converter 208, the output signal to the external device is converted. It is output from the USB connector 204.

The piezoelectric vibration sensor 10A, the sensor module 100A, and the output controller 200A may be individually configured, or may be integrated and attached to the human body with belts 12A and 12B. In this case, the movement of the human body is detected and transmitted by the above-mentioned 3-axis acceleration sensor 214.

Next, the waveform analysis device 300 is composed of a PC (personal computer), a smartphone, a tablet PC, and the like, and includes a CPU 302, a data memory 310, a program memory 320, and a display 304. The program stored in the program memory 320 is executed by the CPU 302. At this time, the data stored in the data memory 310 is referred to. The calculation result is stored in the data memory 310 and displayed on the display 304. All of these basic operations are general and well known.

The data memory 310 stores waveform data 312 received from the output controllers 200A and 200B by wire or wirelessly. In addition, the calculation data 314 which is the calculation result by the CPU 302 is also stored. If necessary, the data in the middle of calculation is also appropriately stored in the data memory 310. A PWV calculation program 322 is prepared in the program memory 320. For smartphones, the program is prepared as an app. The arteriosclerosis evaluation program 324 will be described later.

By the way, it is not possible to verify whether or not the blood flow including the aorta can satisfactorily measure the pulse wave velocity aoPWV on one path in one direction by the present invention. We will demonstrate by making measurements using. FIG. 4 shows the sensor arrangement for the rabbit, and the piezoelectric vibration sensor 20A corresponding to the above-mentioned piezoelectric vibration sensor 10A is attached to the fourth intercostal portion of the chest wall near the apex near the ascending aorta UA, and the heart. Detect bullet waves. Further, the piezoelectric vibration sensor 20B corresponding to the piezoelectric vibration sensor 10B is installed on the skin of the left knee joint portion, and is located at the proximal portion of the left saphenous artery UD from the ascending aorta UA to the abdominal aorta UB and the left femoral artery UC. Detects pulse wave vibration. Similar to FIG. 1, sensor modules 100A and 100B are connected to the output sides of the piezoelectric vibration sensors 20A and 20B, and both are connected to the waveform analysis device 301 via the output controller 200.

Further, in this example, the catheter tip type pressure tongue duster (hereinafter referred to as “catheter pressure sensor”) 22A and 22B are separately installed. As the catheter pressure sensors 22A and 22B, for example, "SPS-320" manufactured by Mirror Co., Ltd. is used. The catheter pressure sensor 22A is installed near the aortic valve of the ascending aorta UA, for example, at the ascending aorta site 5 to 10 mm peripheral from the aortic valve, and the catheter pressure sensor 22B is installed at the distal end of the abdominal aorta UB. A polygraph system 402 is connected to the signal output side of the catheter pressure sensors 22A and 22B via sensor controllers 400A and 400B, respectively. The polygraph system 402 measures the pressure change in the catheter pressure sensors 22A and 22B.

The measurement results of the catheter pressure sensors 22A and 22B by the polygraph system 402 are input to the waveform analysis device 301 described above via an appropriate I / F (interface) 404. The waveform analysis device 301 has the same basic configuration as the waveform analysis device 300 of FIG. 1, but differs in that signal analysis is performed on the catheter pressure sensors 22A and 22B.

Next, the operation of this embodiment will be described with reference to FIGS. 5 to 8. As shown in FIG. 4, in the rabbit example, the piezoelectric vibration sensors 20A and 20B detect the cardiac bullet wave and the pulse wave, respectively, and the catheter pressure sensors 22A and 22B detect the pressure change in the blood vessel at the installation position, respectively. Will be done. FIG. 5 shows an example of those measurements.
Graph ch1: Cardiac wave by piezoelectric vibration sensor 20A installed on the chest,
Graph ch2: Pressure pulse wave by catheter pressure sensor 22A installed in the ascending aorta,
Graph ch3: Pulse wave by piezoelectric vibration sensor 20B installed on the skin of the left knee joint,
Graph ch4: Pressure pulse wave by catheter pressure sensor 22B installed at the distal end of the abdominal aorta,
Each waveform of is shown. The horizontal axis of FIG. 5 indicates time (seconds), and the vertical axis indicates signal strength.

Focusing on ch1 and ch2 among these graphs, the peak of graph ch1 by the piezoelectric vibration sensor 20A installed non-invasively on the chest and the rising point of graph ch2 of the catheter pressure sensor 22 installed in the ascending aorta are Exact match (see PG in the figure). Then, by detecting the waveform detected by the piezoelectric vibration sensor 20A installed non-invasively on the chest, it is considered that the same result as the waveform detection by the catheter pressure sensor 22 installed in the ascending aorta can be obtained. Be done.

The pressure change waveform of the catheter pressure sensor 22A is the pressure change of blood pumped by the operation of the heart valve and indicates the pulse wave departing from the heart. Therefore, the cardiac bullet wave detected by the piezoelectric vibration sensor 20A is a pulse. It can be considered that the timing when the wave departed from the heart is well represented. Applying this result to the case of the human body shown in FIG. 1, it is possible to know the timing at which the pulse wave departs from the heart by detecting the cardiac bullet wave with the piezoelectric vibration sensor 10A fixed to the sternum by the belt 12A. Will be possible. Since the heart valve operation vibration is transmitted through the skeleton, etc., the heart bullet wave is a waveform that is transmitted at a higher speed than the pulse wave. By measuring the heart bullet wave, the pulse wave becomes the heart. You can know the timing that occurred in. That is, by using the cardiac bullet wave, it is possible to accurately determine the propagation velocity of the pulse wave, and it is possible to improve the accuracy of the arteriosclerosis diagnosis.

Returning to FIG. 1, the pulse wave is measured by the piezoelectric vibration sensor 10B fixed to the inguinal region with the belt 12B. The measurement data of the piezoelectric vibration sensors 10A and 10B are input to the waveform analysis device 300 via the sensor modules 100A and 100B and the output controllers 200A and 200B, respectively, and are stored in the data memory 310 as waveform data 312. In the CPU 302, the PWV calculation program 322 of the program memory 320 is executed, and the pulse wave velocity is calculated with reference to the waveform data 312. The calculation result is stored in the data memory 310 as calculation data 314 and is displayed on the display 304. Also, if necessary, it is output to the printer.

In this case, in order to calculate the pulse wave velocity, the time difference between the heart bullet wave and the pulse wave and the distance from the position of the piezoelectric vibration sensor 10A for the heart bullet wave to the position of the piezoelectric vibration sensor 10B for the pulse wave are calculated. It is necessary to know the length of the blood vessel, which is, but in general, it can be estimated from the height of the person to be measured. The pulse wave velocity thus obtained is the pulse wave velocity including the entire aorta and a part of the lower limb artery.

FIG. 6 shows an example of measuring the pulse wave velocity in a rabbit (the same applies to the human body). Fig. (A) shows an example of measuring the pulse wave velocity by two paths such as the upper arm-ankle pulse wave velocity baPWV, and Fig. (B) uses the cardiac bullet wave according to this example. An example of measuring the pulse wave velocity of one path is shown. The horizontal axis of the graph indicates time (msec), the vertical axis indicates distance (mm), and the slope of the graph indicates speed. In these graphs, # 0 to # 3 indicate the installation site of the sensor and are as follows. The piezoelectric vibration sensor 20A was mounted on the skin of the upper right arm when measuring the upper arm-ankle pulse wave velocity baPWV, and was mounted on the skin of the fourth intercostal region of the left chest wall when measuring the cardiac bullet wave.
# 0: Upper arm # 1: Aortic origin # 2: Common iliac artery bifurcation # 3: Ankle

First, to explain from the figure (A),
Brachial PWV: Pulse wave velocity from aortic origin # 1 to brachial # 0
baPWV: Propagation speed of pulse wave from upper arm # 0 to ankle # 3
aoPWV: Pulse wave velocity including the aorta from the aortic origin # 1 to the common iliac artery branch # 2 Lower limb PWV: Pulse wave velocity from the common iliac artery branch # 2 to the ankle # 3 The propagation velocity of the pulse wave from the origin # 1 to the ankle # 3 is upper arm PWV + baPWV or aoPWV + lower limb PWV. Of these, the value of the brachial-ankle pulse wave velocity baPWV, which is a two-path PWV, varies greatly depending on the length of the lower limbs and upper limbs (or the degree of arteriosclerosis thereof).

On the other hand, in the figure (B), instead of the upper arm PWV + baPWV,
Cardiac wave PWV: The propagation velocity of the pulse wave from the upper arm # 0 to the ankle # 3 measured using the cardiovascular wave can be obtained. The effect of the lower limbs remains even with the one-path PWV, the heart bullet wave PWV, but if the lower limb part is short, the lower limb PWV becomes shorter, and the heart bullet wave PWV can be made as close as possible to the pulse wave velocity aoPWV including the aorta. Therefore, if the lower limb PWV is measured separately, the pulse wave velocity aoPWV including the aorta can be accurately estimated from the cardiac bullet wave PWV.

Further, in the figure (B), the time difference between the peaks of the two lower left parts # 0 and # 1 is about 2 ms. Assuming that the distance between the aortic valve inserted into the heart of the rabbit and the tip of the catheter is 10 mm, the PWV during this period is 5 m / s, and the value of the pulse wave velocity aoPWV including the aorta measured by the catheter pressure sensor 22A (4.93 m / s). ) Matches well.

In FIG. 7, the pulse wave velocity aoPWV (horizontal axis) including the aorta obtained from the catheter pressure sensors 22A and 22B attached to the rabbit, and the BC GaoPWV obtained from the time difference between the piezoelectric vibration sensor 20A and the catheter pressure sensor 22B ( The correlation with (vertical axis) is shown. In addition, "BCG" is an English abbreviation for a heart bullet wave, and the pulse wave velocity aoPWV including the aorta obtained by using the heart bullet wave is described as "BCG aoPWV". As a result of performing regression analysis by the least squares method etc. from the measured values indicated by black circles,
a, Regression line G20: BCGaoPWV = 1.0821 ・ aoPWV
b, Correlation coefficient R-squared value: R ² = 0.9517
It was found that there is an extremely strong correlation between the pulse wave velocity aoPWV including the aorta and BC GaoPWV.

In FIG. 8, the pulse wave velocity aoPWV (horizontal axis) including the aorta obtained from the catheter pressure sensors 22A and 22B and the BC GaoPWV + lower limb PWV (vertical axis) obtained non-invasively from the time difference between the piezoelectric vibration sensors 20A and 20B. ) Is shown. As a result of performing regression analysis by the least squares method etc. from the measured values indicated by black circles,
a, Regression line G30: BCGaoPWV + lower limb PWV = 1.516 ・ aoPWV-169.82
b, Correlation coefficient R-squared value: R ² = 0.9465
It was found that there is an extremely strong correlation between the pulse wave velocity aoPWV including the aorta and BC GaoPWV + lower limb PWV. The results shown in FIGS. 7 and 8 are all for rabbits, but it is considered that similar results can be obtained for humans.

As described above, according to this embodiment, there are the following effects.
a, The pulse wave velocity including the aorta can be measured by the time difference of one path including the aorta, not the time difference of two paths from the heart such as the conventional brachial-ankle pulse wave velocity baPWV and cfPWV. ..
b. It is possible to accurately detect the pulse wave velocity by a very simple and non-invasive method.
c. The cardiac bullet wave can be detected in the sternum, and the cardiac bullet wave signal corresponding to the pulse wave signal near the ascending aorta bifurcation position can be easily obtained. By finding the time difference between this and the pulse wave signal that can be detected at the site where the arteries of the lower body such as the thigh and the back of the knee are near the body surface, the pulse wave velocity on one path from the heart including the aorta is simplified. It can be detected accurately by a non-invasive method.

Next, Example 2 of the present invention will be described with reference to FIG. FIG. 9 shows a graph comparing an example of the pulse wave velocity measured using a disease model animal in which an atherosclerotic lesion appears with a normal case. Normal rabbits and WHHLMI rabbits were used, and are known as models that spontaneously develop myocardial infarction in addition to hyperlipidemia and arteriosclerosis.
a, Normal control group: Japanese white rabbit, male, 12 months old, N = 7
b, Arteriosclerosis group: WHHLMI rabbit, male, 12 months old, N = 5
N is an example number.

Rabbits to be tested were fixed in the supine position under pentobarbital (30 mg / kg) anesthesia, and butorphanol tartrate (0.3 mg) was intramuscularly administered as an analgesic. Then, the piezoelectric vibration sensor 20A shown in FIG. 4 was mounted between the third intercostal space of the left chest wall, and the piezoelectric vibration sensor 20B was mounted on the skin inside the left knee. The distance between the sensors was measured along the thread along the artery.

FIG. 9 is a graph of the measurement results, showing Mean ± SD (mean (standard deviation)) of BC GaoPWV + lower limb PWV. As shown in the figure, it can be seen that the pulse wave velocity including the aorta determined non-invasively is faster in WHHLMI rabbits than in normal rabbits. This suggests that the vascular wall of the aorta of WHHLMI rabbits is stiff. Then, when the value of the pulse wave velocity is larger than the normal value, it can be considered that there is a possibility of arteriosclerosis, and the present invention is used to predict the existence of arteriosclerosis and diagnose arteriosclerosis. Can be used as an aid.

The arteriosclerosis evaluation program 324 shown in FIG. 2 has a function of comparing the value of the pulse wave velocity calculated from the measured waveform data with the normal value. The normal value can be obtained in advance by measuring a large number of people. By executing this arteriosclerosis evaluation program 324 on the CPU 302, the value of the pulse wave velocity of the subject is compared with the normal value, and if it exceeds the normal value, it is evaluated that there is a possibility of an arteriosclerosis lesion. The evaluation result is displayed on the display 304.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the following are also included.
(1) In the above-described embodiment, the piezoelectric vibration sensor 10A for cardiac bullet waves is arranged on the sternum side, but the skeletal or skeletal muscles such as the spine and coccyx that are connected without including joints when viewed from the heart. It may be installed on any surface side of the body. Further, in the above embodiment, the piezoelectric vibration sensor 10B for pulse wave is arranged on the thigh, but it may be installed on any part as long as the artery of the lower body is near the body surface such as the back of the knee. If vibration can be detected on the body surface side in this way, the piezoelectric vibration sensors 10A and 10B can be attached to various objects such as chair armrests and backrests, bed mattresses and pillows, as long as they are in contact with people. It's okay.
(2) Piezoelectric vibration sensors 10A and 10B may be installed so as to be in direct contact with the body surface, but are installed via an intermediate medium that transmits vibration, such as urethane or a fiber compressor (Airweave (registered trademark), etc.). You may try to do it.
(3) The circuit configurations shown in FIGS. 1, 2 and 4 are also examples, and various forms having the same effect can be considered. Further, any two or more of the sensor module, the output controller, and the waveform analysis device may be integrally configured, or may be integrally configured with the piezoelectric vibration sensor.
(4) As the piezoelectric vibration sensors 10A and 10B, the same ones may be used, but those having characteristics according to the detected vibration waveform may be used.
(5) Although the above-mentioned example is an example applied to the detection of the human pulse wave velocity of the present invention, it can be generally applied to a living body.

According to the present invention, the pulse wave and the cardiac bullet wave are measured from the output vibration waveform of the piezoelectric vibration sensor installed on the body surface side of the living body, and the pulse wave velocity is calculated by using them. In the medical field, it is possible to obtain a good pulse wave velocity of the aorta on one path where blood flow is unidirectional, and it is also effective for evaluation of arteriosclerosis by a non-invasive method despite its simple structure. Suitable for.

10A, 10B, 20A, 20B: piezoelectric vibration sensor 12A, 12B: belt 22A, 22B: catheter pressure sensor 100A, 100B: sensor module 102: instrumentation amplifier 104: analog switch 105: resistance array 106: low pass filter 108: signal conversion Units 200, 200A, 200B: Output controller 202: Input terminal 204: USB connector 206: Low pass filter 208: USB serial converter 210: Communication module 214: Axis acceleration sensor 216: Charge control circuit 218: Discharge protection circuit 220: Lithium ion charging Batteries 300, 301: Waveform analyzer 302: CPU
304: Display 310: Data memory 312: Waveform data 314: Arithmetic data 320: Program memory 322: Arithmetic program 324: Arteriosclerosis evaluation program 400A, 400B: Sensor controller 402: Polygraph system 404: I / F

Claims (9)

The first piezoelectric vibration sensor, which is installed on the surface side of the living body and detects the cardiac bullet wave,
A second piezoelectric vibration sensor that is installed on the surface side of the living body and detects pulse waves,
A calculation means for calculating the pulse wave velocity using the heart bullet wave obtained by the first piezoelectric vibration sensor and the pulse wave obtained by the second piezoelectric vibration sensor.
A pulse wave velocity measuring device equipped with. The pulse wave velocity measuring device according to claim 1, wherein the first piezoelectric vibration sensor is installed on the body surface side of a skeleton or skeletal muscle that is connected without including a joint. The pulse wave velocity measuring device according to claim 2, wherein the skeleton is any one of a sternum, a spine, and a coccyx. The pulse wave velocity measurement according to any one of claims 1 to 3, wherein the second piezoelectric vibration sensor is installed in a portion of the lower body of a living body where an artery is near the surface of the body. Device. The pulse wave velocity measuring device according to claim 4, wherein the second piezoelectric vibration sensor is installed on the thigh or the back of the knee. The calculation means is
The cardiac departure time of the pulse wave obtained from the cardiac bullet wave obtained by the first piezoelectric vibration sensor, and
The arrival time of the pulse wave obtained by the second piezoelectric vibration sensor and
From the distance of the pulse wave propagation path from the heart to the measurement site of the second piezoelectric vibration sensor,
The pulse wave velocity measuring device according to any one of claims 1 to 5, wherein the pulse wave velocity is calculated. The pulse wave velocity measuring device according to any one of claims 1 to 6, wherein the aorta is included in the propagation path of the pulse wave detected by the second piezoelectric vibration sensor. An arteriosclerosis evaluation device using the pulse wave velocity measuring device according to claims 1 to 7.
The pulse wave velocity of the living body measured by the pulse wave velocity measuring device is compared with the pulse wave velocity of a normal living body in which arteriosclerosis has not occurred, and the pulse wave velocity of the living body is the normal. An arteriosclerosis evaluation device comprising an evaluation means for evaluating the possibility of an arteriosclerotic lesion when the pulse wave velocity exceeds the pulse wave velocity. A step of installing a first piezoelectric vibration sensor for detecting a cardiac bullet wave and a second piezoelectric vibration sensor for detecting a pulse wave on the body surface side of a living body, respectively.
The step of obtaining the cardiac departure time of the pulse wave from the cardiac bullet wave obtained by the first piezoelectric vibration sensor, and
The step of obtaining the arrival time from the pulse wave obtained by the second piezoelectric vibration sensor, and
A step of calculating the pulse wave velocity from the heart departure time of the pulse wave, the arrival time of the pulse wave, and the distance of the pulse wave propagation path from the heart to the measurement site of the second piezoelectric vibration sensor.
A method for measuring pulse wave velocity including.

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