JP2015058199A - Pulse wave propagation velocity-measuring method, and pulse wave propagation velocity-measuring device - Google Patents

Abstract

[PROBLEMS] To reduce the effects of pulse wave propagation characteristics of arteries between the heart and upper arm and between the heart and ankle arteries and fluctuations in transient pulse wave velocity, regardless of individual differences such as age and height. The present invention provides a method capable of increasing the measurement accuracy of the pulse wave velocity between the heart and the ankle.
A pulse wave arrival time Thb from the heart to the upper arm and a pulse wave arrival from the heart to the ankle based on the detection values of the first and second pulse wave sensors attached to the upper arm and the ankle and the electrocardiographic sensor. Each time Tha is specified. Further, based on the height and age, the linear distance between the heart and the upper arm and the linear distance between the heart and the ankle, which are measured on the body surface of the subject, are determined as the arterial length Lhb between the heart and the upper arm, and the arterial length Lha between the heart and the ankle. Respectively. Then, the pulse wave velocity Vxa in the artery from the heart to the ankle is obtained by the following equation. Vxa = (Lha−x) / (Tha−Thb) where x = Lhb × Vha / Vhb.
[Selection] Figure 4

Description

  The present invention relates to a pulse wave velocity measuring method and a pulse wave velocity measuring device for measuring a pulse wave velocity in an artery.

  In general, when arteriosclerosis proceeds, the inner wall of the blood vessel loses its elasticity and the propagation speed of the pulse wave increases. Therefore, as a technique for measuring the propagation velocity of the pulse wave in the artery and diagnosing the degree of arteriosclerosis, the aortic wave propagation velocity method (hereinafter referred to as “cfPWV”) and the pulse wave propagation velocity method between the upper arm and the ankle (hereinafter referred to as “the arterial stiffness”). , “BaPWV”) and the like.

In cfPWV, in order to detect a pulse wave at the neck, it is necessary to attach a pulse wave sensor to the neck as the first part of the subject and to the groin that is the thigh root as the second part of the subject. Therefore, it is difficult to wear the pulse wave sensor, and a burden such as a feeling of pressure given to the subject is large, and the wearing position, the behavior of the subject, and the like affect the measurement result.
In contrast, in baPWV, the first and second pulse wave sensors are attached to the upper arm as the first part of the subject and the ankle as the second part, respectively, and the pulse wave between the upper arm and the ankle is measured. Based on the time shift, the propagation time is obtained.

  The baPWV is measured by a pulse wave sensor that detects the rise of the pulse wave at the upper arm and an ankle, and an electrocardiographic sensor that is used as a marker when detecting a feature point of the pulse wave. In any case, it is easy to wear, has a small burden on the subject, and has a certain correlation with cfPWV, and thus has attracted attention as an effective measurement method for diagnosing the degree of arteriosclerosis.

In order to accurately calculate the pulse wave propagation speed, it is necessary to accurately determine the actual arterial length between the two points where the pulse wave is measured and the time required to propagate the pulse wave in the target artery. It is.
Therefore, in order to accurately determine the pulse wave propagation velocity of the artery from the heart to the ankle, the actual artery length from the heart to the ankle is measured by MRI or the like, and then the aortic valve outlet of the heart is measured. The pulse wave detected at the ankle is identified with reference to the pulse wave detected at step 1, the propagation time of the pulse wave in one artery from the heart to the ankle is detected, and the actual artery length / (heart-ankle propagation It is ideal to calculate in terms of time.

  However, it is practically impossible for all subjects to measure the actual arterial length by MRI or to detect the pulse wave at the aortic valve outlet of the heart from the viewpoint of cost, time, and physical burden required for the examination. It is.

Therefore, in baPWV, the pulse wave velocity is obtained as follows.
(1) The blood vessels including the aorta are not straight, but are curved and meandering in various directions in the body. In addition, the divergence with respect to the straight line distance also increases depending on aging and height. Therefore, the statistical data of the blood vessel length corresponding to α (linear distance between the upper sternum and the ankle) and β (linear distance between the upper sternum and the upper arm) measured on the subject's body surface is mapped to measure arteriosclerosis By inputting the age, height, etc. of the subject into the apparatus, the value is corrected to approximate the actual blood vessel length.
(2) The steep rise of the pulse wave detected by the upper arm is moved over the aorta between the heart and ankle by the same distance as the distance from the heart to the upper arm (approximate value of blood vessel length between the heart and the upper arm) obtained from β. It is regarded as the rising of the moving pulse wave.
Based on the time difference between the steep rise of the pulse wave detected by this upper arm and the steep rise of the pulse wave detected by the ankle, the propagation time was measured and calculated in (1) [(Between heart and ankle )-(Approximate value of blood vessel length between heart and upper arm)] by this propagation time, from a site on the aorta at the same distance as the blood vessel length from the heart to the upper arm, The propagation speed of the pulse wave in the artery reaching the ankle is calculated.

In the arteriosclerosis inspection apparatus disclosed in Patent Document 1, the pulse wave velocity (pulse wave velocity information) PWV, blood pressure BP (SYS), heart rate is calculated from the relational expression stored in advance by the parameter calculation means for arteriosclerosis evaluation. The number HR, the precursor ejection period PEP, and the ejection time ET are measured, and the amplitude increase index AI _E that is a parameter for evaluating arteriosclerosis is calculated.

JP 2003-250769 A

As described above, in baPWV, the propagation distance (blood vessel length) of the pulse wave is estimated from the linear distance actually measured on the subject's body surface, statistical data such as height and age, and the artery from the heart to the ankle , The pulse wave rises at the same timing as the pulse wave measured by the upper arm at a site separated from the heart by the distance between the upper arm parts, and is considered to propagate in the ankle direction.
Therefore, [(Approximate value of blood vessel length between the heart and ankle)-(Approximate value of blood vessel length between the heart and the upper arm)] estimated from the height, age, etc. of the subject is calculated between the brachial pulse wave and the ankle arm wave. By dividing by the propagation time, the propagation speed is obtained and used as an index of the degree of arteriosclerosis.

  However, the arteries from the heart to the upper arm and the arteries from the heart to the ankle are essentially different in vascular characteristics (elasticity, thickness, etc.) regardless of their health status and age. Influenced by age.

  In baPWV, the rise of the pulse wave at the ankle is used as a reference for the arrival of the pulse wave, so it is necessary to determine the rise of the pulse wave corresponding to the pulse wave at the starting point of the aortic valve outlet of the heart. There is. However, it is impossible to accurately record the pulse wave at the aortic valve outlet of the heart without imposing a heavy burden on the subject. Therefore, the pulse wave sensor is attached to the upper arm of the subject, and the detected rise of the pulse wave of the upper arm is regarded as the rise of the pulse wave moving on the aorta at the same distance as the blood vessel length from the heart to the upper arm. However, there is a difference in the pulse wave velocity between the heart-brain artery and the heart-ankle artery, which may cause a decrease in reliability, such as the measured propagation velocity becoming physiologically contradictory values. It has become.

  FIG. 1 shows baPWV (open diamond), faPWV (open square: pulse wave velocity of the lower limb artery), hbPWV (open triangle: pulse wave velocity of the artery from the heart to the upper arm: triangle). , CfPWV (open circle; pulse wave velocity of only the aorta) shows how the measurement result of the pulse wave velocity changes for each age.

  Except for the measurement result by faPWV, the measurement result of the pulse wave propagation velocity increases with a substantially constant slope as the age increases. However, the measurement result by baPWV is assumed to include both the artery from the position of the aorta away from the heart by the same distance as the blood vessel length from the heart to the upper arm, and the artery leading to the lower limb artery via the femoral artery. Therefore, physiologically, the measurement result by faPWV should be an intermediate value between the measurement result by cfPWV and the measurement result by faPWV. Even when compared with, the highest measured value is shown.

This cause can be analyzed as follows.
That is, as described above, the conventional baPWV substitutes the pulse wave of the point on the aorta located at a position away from the heart by the same distance as the blood vessel length from the heart to the upper arm, and records the pulse wave with the upper arm. ing.
Then, the pulse wave velocity from the heart to the ankle is considered to be equal to the pulse wave velocity from the heart to the upper arm, and as shown on the left side of FIG. ) − (Arterial length between the heart and the upper arm)] is changed to [(pulse wave arrival time to the ankle) − (pulse wave arrival time to the upper arm)], that is, a steep rise of the pulse wave detected by the upper arm, The pulse wave propagation velocity in the artery from the heart to the ankle is obtained by dividing by the time from the steep rise of the pulse wave detected at the ankle.

  However, considering the composition of the arterial wall, the pulse wave velocity from the heart to the ankle is faster than the pulse wave velocity from the heart to the upper arm. Therefore, as shown on the right side of FIG. 2, during the period from when the pulse wave reaches the upper arm, the pulse wave propagating from the heart to the artery reaching the ankle actually reaches the upper arm from the heart. From the distance up to, it is going to the periphery.

Thus, when the pulse wave reaches the upper arm, the artery from the heart to the ankle advances from the blood vessel length between the heart and the upper arm, [(pulse wave arrival time to the ankle)-( [(Arterial length between the heart and ankle) − (arterial length between the heart and upper arm)] is longer than the original distance (Actual length) to be divided by the pulse wave arrival time. This dissociation becomes more prominent with age and the like.
For this reason, in baPWV, the calculated pulse wave velocity is higher than the actual pulse wave velocity, and in particular, as the age increases, the pulse wave propagates from the heart to the ankle and from the heart to the upper arm. The difference in the characteristics of the arteries becomes remarkable, and it is considered that this is the main cause that the values of faPWV and baPWV are reversed according to the age as shown in FIG.

  Therefore, the present invention reduces the difference in the pulse wave propagation characteristics between the heart-to-arm artery and the heart-ankle artery, and the blood flow velocity is measured by baPWV regardless of individual differences such as age and height. The purpose is to increase the accuracy and enable an accurate diagnosis of the degree of arteriosclerosis.

In order to solve the above problems, in the pulse wave velocity measuring method of the present invention, the first step of inputting the height and age of the subject, the first pulse wave sensor and the second pulse wave on the upper arm and ankle of the subject. A second step of attaching an electrocardiographic sensor to the left and right wrists of the subject, measuring the heart-to-arm linear distance, and the heart-to-ankle linear distance on the body surface and inputting the third sensor. The pulse wave arrival time Thb from the heart to the upper arm and the pulse wave arrival time Tha from the heart to the ankle are respectively identified based on the detected values of the two pulse wave sensors and the electrocardiographic sensor, and the difference between the two The fourth step of calculating the pulse wave propagation time (Tha-Thb) in the above, based on the height and age, the measured linear distance between the heart and the upper arm, and the linear distance between the heart and the ankle, Arterial length Lhb and between heart and ankle The fifth step of converting to the pulse length Lha, the heart-to-upper arm arterial length Lhb is divided by the pulse-wave arrival time Thb from the heart to the upper arm to obtain the average pulse-wave propagation velocity Vhb between the heart and the upper arm. A sixth step of calculating a heart wave-ankle pulse wave propagation velocity Vha by dividing the heart-ankle artery length Lha by the pulse wave arrival time Lha from the heart to the ankle. It has a process.
Then, the pulse wave velocity Vxa in the artery from the heart to the ankle is obtained by the following equation.
Vxa = (Lha−x) / (Tha−Thb)
However, x = Lhb × Vha / Vhb.

In addition, the pulse wave velocity measuring device that realizes the above-described pulse wave velocity measuring method includes the height and age of the subject, the linear distance between the heart and the upper arm measured on the body surface of the subject, and the straight line between the heart and the ankle. An input device for inputting a distance, a first pulse wave sensor attached to the subject's upper arm, a second pulse wave sensor attached to the subject's ankle, and an electrocardiographic sensor attached to the left and right wrists of the subject are connected. And a pulse wave arrival time Thb between the heart and the ankle, and a pulse wave arrival time Tha between the heart and the ankle, based on the detection values of both pulse wave sensors and the electrocardiographic sensor. And a pulse wave propagation time calculating means for calculating the difference between the two (Tha-Thb), and the inputted linear distance between the heart and the upper arm based on the height and age input from the input device. For the arterial length Lhb between the heart and the upper arm, An arterial length conversion means for converting a linear distance between the viscera and ankles to an arterial length Lha between the heart and ankles, and a heart-first measurement based on the pulse wave arrival time, height and age between the heart and the first part. An arterial length correcting means for correcting a linear distance between one part to a second arterial length from a heart to a pulse wave arrival position in an artery reaching the second part, and an arterial length Lhb between the heart and the upper arm, By dividing by the pulse wave arrival time Thb from the heart to the upper arm, the means for calculating the pulse wave average propagation velocity Vhb between the heart and the upper arm, and the heart-to-ankle artery By dividing the length Lha by the pulse wave arrival time Lha from the heart to the ankle, the heart-ankle pulse wave average propagation velocity Vha for obtaining the heart-ankle pulse wave average propagation velocity Vha, and pulse wave propagation A speed calculation means is provided. This pulse wave propagation velocity calculation means obtains a pulse wave propagation velocity Vxa in an artery from the heart to the ankle according to the following equation.
Vxa = (Lha−x) / (Tha−Thb)
However, x = Lhb × Vha / Vhb.

The above-mentioned Vha and Vhb have individual differences such as height and age depending on the pulse wave propagation characteristics of the artery between the heart and the upper arm and between the heart and the ankle, but this difference is compensated by using the speed ratio. be able to. Further, both Vha and Vhb include a fluctuation of the transient pulse wave velocity from the proximal part of the aortic valve outlet of the heart, and this fluctuation is greatly influenced by individual differences such as height and age. However, both are substantially proportional to the average velocity of each pulse wave average propagation velocity, and by setting Vha / Vhb, the fluctuation can be offset.
As a result, the pulse propagation velocity in the artery between the heart and the ankle can be accurately calculated, and an accurate diagnosis of the degree of arteriosclerosis can be performed.

FIG. 1 is a diagram comparing pulse wave propagation velocities measured between various sites by age. FIG. 2 is a diagram showing an error that occurs when the pulse wave velocity from the heart to the ankle and the pulse wave velocity from the heart to the upper arm are considered to be equal. Note that hbPWV is an average pulse wave velocity from the heart to the upper arm, and haPWV is an average pulse wave velocity from the heart to the ankle. FIG. 3 is a diagram showing a schematic configuration of the pulse wave velocity measuring device. FIG. 4 is a principle diagram for calculating the pulse wave velocity between the heart and the ankle. FIG. 5 is a diagram in which the pulse wave propagation velocity Vxa (black diamond) calculated based on Example 1 is added to FIG. 1 to show the effect of the present invention.

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

FIG. 3 shows a schematic configuration of a pulse wave velocity measuring device based on the present embodiment.
The pulse wave velocity measuring device includes a CPU, a memory, an input / output device, a display / output unit such as a display or a printer, and the like. An electrocardiographic sensor attached to the wrist of the subject and a first pulse wave sensor attached to the upper arm. The second pulse wave sensor attached to the ankle is connected.

  FIG. 4 shows a principle diagram when measuring the degree of arteriosclerosis using the baPWV of the present embodiment. The degree of arteriosclerosis is measured in the following procedure.

(1) Measure on the subject's body surface by α (linear distance from the upper sternum to the upper arm) and β (linear distance from the upper sternum to the ankle).

(2) The blood vessels including the aorta are not straight, but are curved and meandering in various directions in the body. Moreover, because the deviation from the straight line distance increases even with age and height, the subject's measurement value for (straight line distance from the upper sternum to the upper arm) and (straight line distance from the upper sternum to the ankle) Make corrections considering age, height, etc. Specifically, in the inspection device, a database mapped in advance by the age and height of the subject is registered in advance, and the correction value is called by inputting the age and height of the subject,
Lhb = value approximating the actual blood vessel length from the heart to the upper arm Lha = value approximating the actual blood vessel length from the heart to the ankle, respectively.
The heart position is h (heart), the upper arm position is b (brachial), and the ankle position is a (ankle). Hereinafter, for example, hb means between the heart and the upper arm, and ha means between the heart and the ankle. .

(3) Next, electrocardiographic sensors are attached to the left and right wrists of the subject, and the first pulse wave sensor and the second pulse wave sensor are attached to the upper arm as the first part and the ankle as the second part, respectively. , Start measurement by each sensor

(4) From the relationship between the R wave measured by the electrocardiographic sensor, the sharp rise of the brachial pulse wave specified by the first pulse wave sensor and the second pulse wave sensor, and the sharp rise of the ankle pulse wave,
Thb = time from electrocardiogram R wave to rise of brachial pulse wave Tha = time from electrocardiogram R wave to rise of ankle pulse wave is obtained.

(5) By dividing Lhb and Lha obtained in (2) by Thb and Tha propagation time measured in (4),
Velocity between heart and upper arm: Vhb = Lhb / Thb
Velocity between heart and ankle: Vha = Lha / Tha
For each.

Here, in order to accurately calculate the pulse wave propagation velocity for the artery from the heart to the ankle, at the time of t = Thb when the specified pulse wave reaches the upper arm, which of the arteries from the heart to the ankle is determined. It is to accurately predict whether or not the part has been reached.
So, if this part is at a distance x from the heart,
By dividing (Lha-x) by (Tha-Thb), the pulse wave velocity in the artery from the heart to the ankle can be accurately calculated.

In this embodiment, x is calculated by the following equation.
x = Lhb × Vha / Vhb (1)
That is, x is calculated by multiplying Lhb by the ratio of Vha to Vhb.
Using the thus obtained x, the pulse wave velocity Vxa reaching the ankle can be obtained from the point at the position of the x of the artery reaching the ankle from the heart as follows.
Vxa = (Lha-x) / (Tha-Thb) (2)

  As described above, Vha and Vhb include differences in pulse wave propagation characteristics between arteries between the heart and the upper arm and between the heart and ankle, as well as transient fluctuations in the pulse wave propagation speed. The difference in the pulse wave propagation characteristics is that the velocity ratio is used. Further, since the transient fluctuation of the pulse wave propagation velocity is included in both Vha and Vhb, the average velocity thereof is set to Vha / Vhb. Thus, the fluctuation can be offset.

  FIG. 5 shows the effect of the present embodiment, and the measurement results based on Vxa calculated by the present embodiment are indicated by black diamonds. As is clear when compared with the conventional baPWV (open diamond), the measured value is not exceeded while maintaining the correlation with faPWV (open square) until reaching the age of 65-79. It can be confirmed that the intermediate value with the measurement result by cfPWV is maintained.

With baPWV, it is easy to wear, has little burden on the subject, and has a certain correlation with cfPWV that measures the average pulse wave propagation velocity in the entire artery from the heart to the ankle. However, according to the present invention, it is possible to greatly reduce fluctuations due to individual differences due to height, age, etc., without adding a new sensor or the like. Therefore, it can be expected to be widely adopted as a pulse wave velocity measurement technique that dramatically improves the diagnostic accuracy by the baPWV method.

Claims (2)

A first step of inputting the height and age of the subject,
A second step of attaching the first pulse wave sensor and the second pulse wave sensor to the subject's upper arm and ankle, respectively, and attaching an electrocardiographic sensor to the body surface directly above the subject's heart;
A third step of measuring and inputting the linear distance of the heart-upper arm and the linear distance of the heart-ankle on the body surface;
The pulse wave arrival time Thb from the heart to the upper arm and the pulse wave arrival time Tha from the heart to the ankle are specified based on the detection values of both pulse wave sensors and the electrocardiographic sensor, and the pulse wave is determined by the difference between the two. A fourth step of calculating a propagation time (Tha-Thb);
Based on the height and age, the measured linear distance between the heart and the upper arm and the linear distance between the heart and the ankle are converted into the arterial length Lhb between the heart and the upper arm and the arterial length Lha between the heart and the ankle, respectively. A fifth step of
A sixth step of obtaining a pulse wave average propagation velocity Vhb between the heart and the upper arm by dividing the arterial length Lhb between the heart and the upper arm by a pulse wave arrival time Thb from the heart to the upper arm;
A seventh step of obtaining a pulse wave average propagation velocity Vha between the heart and the ankle by dividing the arterial length Lha between the heart and the ankle by a pulse wave arrival time Lha from the heart to the ankle;
A pulse wave velocity measuring method characterized by obtaining a pulse wave velocity Vxa in an artery from the heart to the ankle according to the following equation.
Vxa = (Lha−x) / (Tha−Thb)
However, x = Lhb × Vha / Vhb. An input device for inputting the height, age of the subject, the linear distance between the heart and the upper arm measured on the body surface of the subject, and the linear distance between the heart and the ankle;
A first pulse wave sensor to be worn on the upper arm of the subject;
A second pulse wave sensor attached to the subject's ankle;
A pulse wave velocity measuring device connected to electrocardiographic sensors to be worn on the left and right wrists of a subject,
Based on the detection values of both pulse wave sensors and the electrocardiographic sensor, the pulse wave arrival time Thb between the heart and the upper arm and the pulse wave arrival time Tha between the heart and the ankle are respectively specified, and the difference between them (Tha-Thb) ) For calculating the pulse wave propagation time,
Based on the height and age input from the input device, the input measured linear distance between the heart and the upper arm is the arterial length Lhb between the heart and the upper arm, and the linear distance between the heart and the ankle canal is the artery between the heart and the ankle. Arterial length conversion means for converting to length Lha;
Based on the pulse wave arrival time, height and age between the heart and the first part, the measured linear distance between the heart and the first part is calculated from the heart to the pulse wave arrival position in the artery reaching the second part. Arterial length correcting means for correcting to the second arterial length;
By dividing the heart-to-arm arterial length Lhb by the pulse-wave arrival time Thb from the heart to the upper arm, the pulse-wave average propagation velocity between the heart and the upper arm is obtained. A calculation means;
The heart-ankle pulse length average propagation velocity Vha is obtained by dividing the heart-ankle artery length Lha by the pulse wave arrival time Lha from the heart to the ankle to obtain the heart-ankle pulse wave average propagation velocity Vha. A calculation means;
A pulse wave velocity calculating means for obtaining a pulse wave velocity Vxa in an artery from the heart to the ankle according to the following equation;
A pulse wave velocity measuring device characterized by comprising:
Vxa = (Lha−x) / (Tha−Thb)
However, x = Lhb × Vha / Vhb.

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