WO2020071480A1

WO2020071480A1 - Device and method for measuring pulse wave velocity

Info

Publication number: WO2020071480A1
Application number: PCT/JP2019/039091
Authority: WO
Inventors: 新一郎勝田; 隆石黒
Original assignee: 公立大学法人福島県立医科大学; 太陽誘電株式会社
Priority date: 2018-10-05
Filing date: 2019-10-03
Publication date: 2020-04-09
Also published as: JPWO2020071480A1

Abstract

[Problem] To accurately detect a pulse wave velocity in one path in the same blood flow direction that includes the aorta, by means of a simple structure and by noninvasive means. [Solution] A piezoelectric vibration sensor 10A serves as a ballistocardiac wave sensor, and piezoelectric vibration sensor 10B serves as a pulse wave sensor. Ballistocardiac waves are a propagation of vibration from heart valve actuation through the medium of the skeleton or skeletal muscles, and are propagated at a higher velocity than pulse waves, and when compared with pulse waves, ballistocardiac waves can be considered to be propagated substantially instantaneously. This being the case, since the time that pulse waves leave the heart can be known from the ballistocardiac waves, the pulse wave velocity can be determined from the time that a pulse wave reaches the measurement site and the distance from the heart to the measurement site.

Description

Pulse wave velocity measuring device and method

{Circle around (1)} The present invention relates to a pulse wave velocity measuring apparatus and method for measuring and analyzing a pulse wave velocity (PWV), which is a change in blood pressure and volume in a vascular system accompanying a heartbeat.

The pulse wave propagation speed is a speed at which a pulse wave generated by the pulsation of the heart propagates toward the periphery, and is known to increase in patients with diseases such as hypertension, diabetes, and cerebral infarction. Atherosclerotic lesions mainly form in the aorta and extend to peripheral artery sites such as the carotid and femoral arteries. Because arteriosclerosis is a risk factor for serious diseases such as ischemic heart disease, cerebrovascular disease, and aortic aneurysm, it is important to diagnose it at an early stage. Pulse wave velocity is attracting attention as an index.

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

Although it is ideal to measure the pulse wave velocity of the aorta where atherosclerotic lesions are remarkable, it is difficult to measure noninvasively and simply with current medicine. Therefore, a method of non-invasively detecting a pulse wave in a peripheral artery and measuring a pulse wave velocity in an artery including the aorta and the peripheral artery has been devised. As a specific example of such a pulse wave velocity, for example, the pulse wave velocity cfPWV between the carotid artery and the femoral artery described in p. 121 and later of “Guidelines on Noninvasive Evaluation Method of Vascular Function” in the following non-patent document: Technology for measuring pulse wave velocities including aorta such as (carotid-femoral PWV) and brachial-ankle PWV (brachial-ankle PWV), and early detection of serious cardiovascular diseases such as aortic dissection Due to the necessity of circulatory organs, it has become widespread in the field of cardiovascular medicine. For example, the following Patent Document, based on the ankle pulse wave WL _L brachial - calculate the ankle between pulse-wave propagation velocity baPWV, lower limb limb blood-pressure index which is adapted to diagnose the stenosis of the lower limb arteries (ankle-brachial index; ABI ) A measuring device is disclosed.

ガイドライン Guidelines on Diagnosis and Treatment of Cardiovascular Diseases (Report of the Joint Research Group 2011-2012) P113-P145 “Digest Version Guidelines on Non-Invasive Evaluation of Vascular Function”

JP 2002-272688 A

However, in the case where the difference in the arrival time of the pulse wave on two paths having different blood flow directions is used instead of the arrival time difference of the pulse wave on one path in one direction, In view of the fact that the propagation velocities differ greatly, it is difficult at present to reflect pulse wave velocities (aortic PWV; aoPWV) of the aorta.

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

The present invention focuses on this point, and an object of the present invention is to accurately detect the pulse wave propagation velocity on one path including the aorta by a simple configuration and by a non-invasive method. Another object is to use the detected pulse wave velocity to assess the likelihood of arteriosclerosis.

The pulse wave propagation velocity measuring apparatus of the present invention is installed on the body surface side of a living body and detects a pulse wave by installing a first piezoelectric vibration sensor that detects a heart wave and a body. A pulse wave propagation velocity is calculated by using a second piezoelectric vibration sensor, a heart wave obtained by the first piezoelectric vibration sensor, and a pulse wave obtained by the second piezoelectric vibration sensor. Calculation means.

According to one of the main aspects, the first piezoelectric vibration sensor is characterized in that the first piezoelectric vibration sensor is installed on a body surface side of a skeleton or a skeletal muscle connected without including a joint. According to another aspect, the skeleton is any one of a sternum, a spine, and a tail base. According to still another aspect, the second piezoelectric vibration sensor is characterized in that the second piezoelectric vibration sensor is disposed in a lower body of a living body and at a site where an artery is near the body surface. Alternatively, the second piezoelectric vibration sensor is installed on a thigh or the back of a knee.

According to still another mode, the calculating means includes a heart departure time of a pulse wave obtained from a cardiac oscillating wave obtained by the first piezoelectric vibration sensor and a pulse departure time obtained by the second piezoelectric vibration sensor. The pulse wave propagation velocity is calculated from the arrival time of the wave and the distance of the propagation path of the pulse wave from the heart to the measurement site of the second piezoelectric vibration sensor. Further, the aorta is included in the propagation path of the pulse wave detected by the second piezoelectric vibration sensor.

The arterial stiffness evaluation device of the present invention is an arterial stiffness evaluation device using the pulse wave velocity measuring device, wherein the pulse wave propagation speed of the living body measured by the pulse wave velocity measuring device and the arteriosclerosis determined in advance. Evaluation means for comparing the pulse wave propagation velocity in a normal living body in which no occurrence has occurred, and evaluating that there is a possibility of an arteriosclerotic lesion when the pulse wave propagation velocity of the living body exceeds the normal pulse wave propagation velocity It is characterized by having.

The method of measuring a pulse wave velocity according to the present invention includes the steps of: installing a first piezoelectric vibration sensor for detecting a cardiac elastic wave and a second piezoelectric vibration sensor for detecting a pulse wave on a body surface of a living body; Obtaining a heart departure time of a pulse wave from a heart trajectory obtained by a first piezoelectric vibration sensor; obtaining a arrival time of the pulse wave from a pulse wave obtained by the second piezoelectric vibration sensor; Calculating a pulse wave propagation velocity from the pulse wave heart departure time, 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 become apparent from the following detailed description and the accompanying drawings.

According to the present invention, a pulse wave and a heart elastic 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 propagation velocity is calculated by using them. In spite of the simple configuration, the pulse wave propagation velocity of the aorta on one path in which the blood flow is one-way can be favorably obtained by a non-invasive method, and it is effective for evaluating arteriosclerosis.

It is a figure showing installation and circuit composition of a piezoelectric vibration sensor in an example of the present invention. FIG. 2 is a diagram illustrating a specific example of the circuit configuration of FIG. 1. FIG. 3 is a diagram showing a pulse wave measurement site in a human in the embodiment. It is a figure showing a sensor part and a measuring device of a pulse wave measurement using a rabbit. It is a figure showing an example of a measurement waveform in the example of the above-mentioned rabbit. It is a figure which shows the example of a measurement of the pulse-wave propagation speed by two paths | paths in the example of the said rabbit, and the pulse-wave propagation velocity of one path | route using a heart bullet. It is a figure which shows the correlation of the pulse wave propagation speed containing the aorta calculated | required from the catheter pressure sensor in the example of the said rabbit, and the pulse wave propagation speed calculated | required from the time difference of the piezoelectric vibration sensor and the catheter pressure sensor. It is a figure which shows the correlation of the pulse wave propagation speed containing the aorta calculated | required from the catheter pressure sensor in the example of the said rabbit, and the pulse wave propagation speed calculated from the time difference of the piezoelectric vibration sensor. FIG. 3 is a graph showing pulse wave velocity measured using WHHLMI rabbits (which genetically develop hyperlipidemia, coronary artery disease and atherosclerosis) and normal rabbits. It is a figure showing the principle of the measuring technique of a pulse wave propagation 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 the present embodiment, two piezoelectric vibration sensors are mounted on the body surface of the subject. Of these, the piezoelectric vibration sensor 10A is fixed to the sternum with a belt 12A, and the piezoelectric vibration sensor 10B is fixed to the groin with a belt 12B. The piezoelectric vibration sensor 10B may be fixed to the sole of the knee, the instep of the foot, or the like. Sensor outputs of the

piezoelectric vibration sensors

10A and 10B are input to

sensor modules

100A and 100B, respectively, and the output sides of the

sensor modules

100A and 100B are connected to a waveform analyzer 300 via

output controllers

200A and 200B. .

Among these, preferred examples of the

piezoelectric vibration sensors

10A and 10B include, for example, a vibration waveform sensor disclosed in WO 2016/167202 and a sensor module disclosed in WO 2017/187710. It is. As the

piezoelectric vibration sensors

10A and 10B, the same ones may be used, or ones having characteristics according to the vibration waveform to be detected may be used. In this embodiment, the piezoelectric vibration sensor 10A is a heart wave sensor, and the piezoelectric vibration sensor 10B is a pulse wave sensor. A cardiac trajectory is a minute vibration of the human body that accompanies pulsation, which is a physical movement caused by contraction and relaxation of the heart muscle, and the vibration associated with the pulsation of the heart is transmitted using the skeleton and skeletal muscle as a medium. Therefore, there is a feature that the pulse wave is transmitted at a higher speed than the pulse wave. A pulse wave propagating through an artery as a medium has a propagation velocity of about 5-20 m / s, whereas a heart bullet has a propagation velocity of the order of km / s. Can be considered transmitted. As a result, the time when the pulse wave departs from the heart can be known from the cardiac trajectory, so that the pulse wave can be obtained from the arrival time of the pulse wave at the measurement site and the distance of the propagation path of the pulse wave from the heart to the measurement site. The wave propagation velocity can be determined.

In the present embodiment, the peak of the heart elastic wave (heart elastic wave signal generated when the heart valve closes) is detected near the sternum, utilizing the fact that the

piezoelectric vibration sensors

10A and 10B can detect the heart elastic wave and the pulse wave, respectively. At the same time, a pulse wave is detected in the vicinity of the femoral artery, and the time difference between the two is taken to realize the time difference measurement of the path including the aorta.

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

Next, an example of the

sensor modules

100A, 100B, the

output controllers

200A, 200B, and the waveform analyzer 300 is shown in FIG. Of course, those disclosed in the pamphlet of International Publication No. 2016/167202 or the pamphlet of International Publication No. 2017/187710 described above may be used. Since the

sensor modules

100A and 100B and the

output controllers

200A and 200B have the same configuration in the present 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 resistor array 105 are for controlling the driving of the instrumentation amplifier 102 based on the signal from the waveform analyzer 300, and combine on / off of the analog switch 104 connected to the resistor array 105. Thus, the resistance value can be changed, and the amplification factor of the instrumentation amplifier 102 can be changed. The output side of the instrumentation amplifier 102 is connected to a signal converter 108 via a low-pass filter 106 for extracting low-frequency components, so that an analog signal is converted to 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 has an input terminal 202 such as a 4-pin jack, a USB connector 204, a low-pass filter 206, The communication module 210 mainly includes a USB serial converter 208 and BLE. The power supply is a lithium ion rechargeable battery 220 charged by the charge control circuit 216, and is provided with a discharge protection circuit 218. The communication module 210 is provided with a three-axis acceleration sensor 214.

のうち Of these, the input terminal 202 is used for signal input from the sensor module 100A. The low-pass component of the input signal is extracted by the low-pass filter 206 and input 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. 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 a human body by the

belts

12A, 12B. In this case, the movement of the human body is detected and transmitted by the above-described three-axis acceleration sensor 214.

Next, the waveform analyzer 300 is constituted by a PC (personal computer), a smart phone, a tablet PC, or the like, and includes a CPU 302, a data memory 310, a program memory 320, and a display 304. The programs stored in the program memory 320 are 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. Such basic operations are general and well-known.

The data memory 310 stores the waveform data 312 received from the

output controllers

200A and 200B by wire or wirelessly. Further, operation data 314 which is an operation result by the CPU 302 is also stored. If necessary, data in the middle of the calculation is also stored in the data memory 310 as appropriate. A PWV calculation program 322 is prepared in the program memory 320. In the case of a smartphone, the program is prepared as an application. The arteriosclerosis evaluation program 324 will be described later.

By the way, it is not possible to verify whether the blood flow including the aorta can properly measure the pulse wave propagation velocity aoPWV on one path in one direction by using the present invention. It will be demonstrated by performing measurement using. FIG. 4 shows a sensor arrangement for a rabbit. A piezoelectric vibration sensor 20A corresponding to the above-described piezoelectric vibration sensor 10A is mounted on the fourth intercostal portion of the chest wall near the apex near the ascending aorta UA. Detects bullet waves. The piezoelectric vibration sensor 20B corresponding to the piezoelectric vibration sensor 10B is installed on the skin of the left knee joint, and is located at the proximal part of the left saphenous artery UD passing from the ascending aorta UA to the abdominal aorta UB and the left femoral pulse UC. Detect pulse wave vibration. 1, the

sensor modules

100A and 100B are connected to the output sides of the

piezoelectric vibration sensors

20A and 20B, respectively, and both are connected to the waveform analyzer 301 via the output controller 200.

Further, in this example, the catheter tip type pressure transducer (hereinafter referred to as “catheter pressure sensor”) 22A, 22B is separately installed. As the

catheter pressure sensors

22A and 22B, for example, "SPS-320" manufactured by Mirror is used. The catheter pressure sensor 22A is installed near the aortic valve of the ascending aorta UA, for example, at the ascending aortic site 5 to 10 mm distal 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 signal output sides of the

catheter pressure sensors

22A and 22B via

sensor controllers

400A and 400B, respectively. The polygraph system 402 measures pressure changes at 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 above-described waveform analyzer 301 via an appropriate I / F (interface) 404. The waveform analyzer 301 has the same basic configuration as the waveform analyzer 300 of FIG. 1, but differs in that it performs signal analysis on the

catheter pressure sensors

22A and 22B.

Next, the operation of this embodiment will be described with reference to FIGS. As shown in FIG. 4, in the rabbit example, the oscillating heart wave and the pulse wave are respectively detected by the

piezoelectric vibration sensors

20A and 20B, and the

catheter pressure sensors

22A and 22B detect the pressure change in the blood vessel at the installation position. Is done. FIG. 5 shows examples of these measurements.
Graph ch1: heart wave caused by the 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 the 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 abdominal aorta,
Are shown. Note that the horizontal axis in FIG. 5 indicates time (seconds), and the vertical axis indicates signal intensity.

Focusing on ch1 and ch2 among these graphs, the peak of graph ch1 by the piezoelectric vibration sensor 20A non-invasively installed on the chest and the rising point of the graph ch2 of the catheter pressure sensor 22 installed in the ascending aorta are shown. They match exactly (see PG in the figure). In conclusion, 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 by detecting the detection waveform by the piezoelectric vibration sensor 20A installed non-invasively on the chest. Can be

The pressure change waveform of the catheter pressure sensor 22A is a pressure change of the blood sent out by the operation of the heart valve, and shows a pulse wave starting from the heart. Therefore, a heart trajectory detected by the piezoelectric vibration sensor 20A is a pulse wave. It can be considered that the wave is a good indicator of the timing of departure from the heart. If this result is applied to the case of the human body shown in FIG. 1, the timing at which the pulse wave departs from the heart can be known by detecting the cardiac elastic wave by the piezoelectric vibration sensor 10A fixed to the sternum by the belt 12A. Can be done. The heart trajectory is a waveform transmitted at a higher speed than the pulse wave because the vibration of the heart valve operation is transmitted through a skeleton or the like. Can be known. That is, the use of the cardiac trajectory makes it possible to accurately determine the propagation speed of the pulse wave, thereby improving the accuracy of the arteriosclerosis diagnosis.

に Returning to FIG. 1, the pulse wave is measured by the piezoelectric vibration sensor 10B fixed to the groin by the belt 12B. The measurement data of the

piezoelectric vibration sensors

10A and 10B are input to the waveform analyzer 300 via the

sensor modules

100A and 100B and the

output controllers

200A and 200B, respectively, and stored in the data memory 310 as waveform data 312. The CPU 302 executes the PWV calculation program 322 in the program memory 320, and calculates the pulse wave propagation velocity with reference to the waveform data 312. The calculation result is stored in the data memory 310 as calculation data 314 and displayed on the display 304. If necessary, it is output to a printer.

In this case, in order to calculate the pulse wave propagation velocity, the distance between the position of the piezoelectric vibration sensor 10A for the cardiac elastic wave and the position of the piezoelectric vibration sensor 10B for the pulse wave is calculated together with the time difference between the cardiac elastic wave and the pulse wave. It is necessary to know the blood vessel length, which can be generally estimated from the height of the subject. 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 a measurement example of the pulse wave velocity in a rabbit (the same applies to a human body). FIG. 7A shows an example of measurement of pulse wave propagation velocities by two routes such as upper arm-ankle pulse wave propagation velocity baPWV, and FIG. The example of measuring the pulse wave propagation 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 upper right arm skin when measuring the pulse wave propagation velocity baPWV between the upper arm and the ankle, and was mounted on the fourth intercostal skin on the left chest wall when measuring the heart trajectory.
# 0: Upper arm # 1: Aortic root # 2: Common iliac bifurcation # 3: Ankle

First, referring to FIG.
Upper arm PWV: Propagation velocity of pulse wave from aortic root # 1 to upper arm # 0
baPWV: Propagation velocity of pulse wave from upper arm # 0 to ankle # 3
aoPWV: Pulse wave propagation velocity including aorta from aortic root # 1 to common iliac artery branch # 2 Lower leg PWV: Pulse wave propagation velocity from common iliac artery branch # 2 to ankle # 3, aorta The propagation speed 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 pulse wave propagation velocity baPWV between the upper arm and the ankle, which is a two-path PWV, greatly changes depending on the length of the lower limb and the upper limb (or the degree of arteriosclerosis thereof).

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

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

FIG. 7 shows the pulse wave propagation velocity aoPWV (horizontal axis) including the aorta calculated from the

catheter pressure sensors

22A and 22B attached to the rabbit, and BCGaoPWV (calculated from the time difference between the piezoelectric vibration sensor 20A and the catheter pressure sensor 22B). (Vertical axis). Note that “BCG” is an abbreviation of the heart trajectory in English, and the pulse wave velocity aoPWV including the aorta obtained using the heart trajectory is described as “BCGaoPWV”. As a result of performing a regression analysis by the least squares method etc. from the measurement values indicated by black circles,
a, Regression line G20: BCGaoPWV = 1.0021 · aoPWV
b, Correlation coefficient R square value: R ² = 0.9517
It was found that there was a very strong correlation between the pulse wave velocity aoPWV including the aorta and BCGaoPWV.

FIG. 8 shows pulse wave propagation velocity aoPWV including the aorta obtained from the

catheter pressure sensors

22A and 22B (horizontal axis) and BCGaoPWV + lower limb PWV obtained non-invasively from the time difference between the

piezoelectric vibration sensors

20A and 20B (vertical axis). ) Are shown. As a result of performing a regression analysis by the least squares method etc. from the measurement values indicated by black circles,
a, Regression line G30: BCGaoPWV + lower limb PWV = 1.516 · aoPWV-169.82
b, Correlation coefficient R square value: R ² = 0.9465
It was found that there was an extremely strong correlation between the pulse wave velocity aoPWV including the aorta and BCGaoPWV + lower limb PWV. These results in FIGS. 7 and 8 are for rabbits, but it is considered that similar results can be obtained for humans.

As described above, according to the present embodiment, the following effects can be obtained.
a, The pulse wave propagation 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 like the conventional brachial-ankle pulse wave propagation velocity baPWV or cfPWV. .
b. It becomes possible to accurately detect the pulse wave velocity by a very simple and non-invasive technique.
(c) While detecting a cardiac trajectory by the sternum, a cardiac trajectory signal corresponding to a pulse wave signal near the ascending aortic bifurcation position can be easily obtained. By calculating the time difference between this and a pulse wave signal that can be detected at a site where the lower body artery such as the thigh or the back of the knee is near the body surface, the pulse wave propagation velocity on one path from the heart including the aorta can be simplified. And can be accurately detected by a non-invasive technique.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a graph comparing an example of a pulse wave velocity measured using a disease model animal in which an arteriosclerotic lesion appears with a normal case. Normal rabbits and WHHLMI rabbits were used, and are known as models for spontaneously developing 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
Note that N is the number of cases.

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

FIG. 9 is a graph of the measurement results, showing Mean ± SD (mean (standard deviation)) of BCGaoPWV + PWV of the lower limb. As shown in the figure, the pulse wave velocity including the aorta obtained non-invasively is higher in the WHHLMI rabbit than in the normal rabbit. This suggests that the aortic vascular wall of the WHHLMI rabbit is stiffened. Therefore, when the value of the pulse wave velocity is larger than the normal value, it can be considered that there is a possibility of an arteriosclerotic lesion. Can be used for assistance.

動脈 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 the arteriosclerosis evaluation program 324 by the CPU 302, the value of the pulse wave propagation velocity of the subject is compared with the normal value, and when it exceeds the normal value, it is evaluated that there is a possibility of an arteriosclerotic lesion. The evaluation result is displayed on the display 304.

The present invention is not limited to the embodiments described above, and various changes can be made without departing from the spirit of the present invention. For example, the following are also included.
(1) In the above-described embodiment, the piezoelectric vibration sensor 10A for cardiac elastic wave is arranged on the sternum side. However, the skeletal or skeletal muscles such as the spine and the tail base that are connected without including the joint when viewed from the heart. May be installed on any of the body surfaces. In the above-described embodiment, the piezoelectric vibration sensor 10B for pulse wave is arranged on the thigh. However, the piezoelectric vibration sensor 10B may be installed on any part of the body such as the back of the knee where the artery of the lower body is near the body surface. As described above, if the vibration can be detected on the body surface side, the

piezoelectric vibration sensors

10A and 10B can be attached to various objects such as armrests and backrests of chairs, mattresses and pillows of beds, etc., as long as they come into contact with humans. May be.
(2) The

piezoelectric vibration sensors

10A and 10B may be installed so as to be in direct contact with the body surface. However, the

piezoelectric vibration sensors

10A and 10B are installed via an intermediate medium that transmits vibration, for example, urethane or a fiber compression body (such as Airweave (registered trademark)). You may make it.
(3) The circuit configurations shown in FIG. 1, FIG. 2, and FIG. 4 are also examples, and various modes having the same operation can be considered. In addition, any two or more of the sensor module, the output controller, and the waveform analyzer 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 vibration waveform to be detected may be used.
(5) The above embodiment is an example in which the present invention is applied to the detection of the pulse wave velocity of a human, but is applicable to general living organisms.

According to the present invention, a pulse wave and a heart elastic 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 propagation velocity is calculated by using them. Despite the simple structure, it is possible to obtain a good pulse wave velocity of the aorta on one path where blood flow is one-way by a non-invasive method, and it is also effective for evaluating arteriosclerosis. It is suitable for.

10A, 10B, 20A, 20B:

Piezoelectric vibration sensors

12A, 12B:

Belts

22A, 22B:

Catheter pressure sensors

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: axial acceleration sensor 216: charge control circuit 218: discharge protection circuit 220: lithium ion charging Battery 300, 301: Waveform analyzer 302: CPU
304: display 310: data memory 312: waveform data 314: operation data 320: program memory 322: operation program 324:

arteriosclerosis evaluation program

400A, 400B: sensor controller 402: polygraph system 404: I / F

Claims

A first piezoelectric vibration sensor that is installed on the body surface side of a living body and detects a heart bullet wave;
A second piezoelectric vibration sensor that is installed on the body surface side of the living body and detects a pulse wave;
Calculating means for calculating a pulse wave propagation velocity using a heart elastic wave obtained by the first piezoelectric vibration sensor and a pulse wave obtained by the second piezoelectric vibration sensor;
A pulse wave velocity measuring device provided with:
4. The pulse wave velocity measuring device according to claim 1, wherein the first piezoelectric vibration sensor is installed on a body surface side of a skeleton or a skeletal muscle 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 tail base.
The pulse wave velocity measurement according to any one of claims 1 to 3, wherein the second piezoelectric vibration sensor is installed in a lower body of a living body and at a site where an artery is near a body surface. apparatus.
5. The pulse wave velocity measuring device according to claim 4, wherein the second piezoelectric vibration sensor is installed on a thigh or a back of a knee.
The arithmetic means is
A heart departure time of a pulse wave obtained from a heart trajectory obtained by the first piezoelectric vibration sensor;
Arrival time of the pulse wave obtained by the second piezoelectric vibration sensor;
From the distance of the propagation path of the pulse wave 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 propagation 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 arterial stiffness evaluation device using the pulse wave velocity measuring device according to any one of claims 1 to 7,
The pulse wave velocity of the living body measured by the pulse wave velocity measuring apparatus is compared with a pulse wave propagation velocity of a normal living body in which atherosclerosis has not been determined in advance, and the pulse wave propagation velocity of the living body is the normal. An arteriosclerosis evaluation device comprising an evaluation means for evaluating that there is a possibility of an arteriosclerotic lesion when the pulse wave velocity exceeds the pulse wave propagation velocity.
Installing a first piezoelectric vibration sensor for detecting a heart wave and a second piezoelectric vibration sensor for detecting a pulse wave on the body surface of a living body,
Obtaining a heart departure time of a pulse wave from a heart trajectory obtained by the first piezoelectric vibration sensor;
Obtaining a time of arrival from a pulse wave obtained by the second piezoelectric vibration sensor;
Calculating the pulse wave propagation velocity from the heart departure time of the pulse wave, the arrival time of the pulse wave, and the distance of the propagation path of the pulse wave from the heart to the measurement site of the second piezoelectric vibration sensor;
A pulse wave velocity measuring method including: