JP3217330B2 - Pulse wave transit time measuring device and left ventricular systolic time measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pulse wave transit time measuring device and a left ventricular systolic time measuring device.
Here, the left ventricular systolic time (Systolic Time Interval =
(STI) refers to the contraction time of the left ventricle of the heart, which is the pre-ejection time from the start of contraction of the left ventricular myocardium to the ejection of blood, and the ejection time of blood ejection from the left ventricle. I have time.

[0002]

2. Description of the Related Art There has been proposed a pulse wave transit time measuring device for measuring a pulse wave transit time in which a pulse wave propagates between two predetermined parts of a living body. This is because the pulse wave transit time or the pulse wave transit speed corresponding to the pulse wave transit time on a one-to-one basis can be used to estimate a blood pressure value, an arteriosclerosis degree, a peripheral resistance, and the like.

[0003] In order to measure the pulse wave transit time, a pulse wave detecting device is attached to each of two predetermined portions of a living body, and the first pulse wave detecting device attached upstream is used to measure a predetermined portion of the first pulse wave. From the detection of the first pulse wave to the detection of the portion corresponding to the predetermined portion of the first pulse wave by the second pulse wave detection device attached downstream of the first pulse wave detection device. It is necessary to calculate as For example, a carotid artery wave detection device attached to the neck of a living body is used as a first pulse wave detection device, and a peripheral pulse wave detection device attached to a fingertip is used as a second pulse wave detection device.

In some cases, an electrocardiographic lead device for detecting an electrocardiographic lead waveform through an electrode attached to a living body is used as the first pulse wave detecting device. Since the ECG waveform represents the activity of the living body's myocardium, it means that the pulse wave at the uppermost stream is detected, so the pulse wave propagation time becomes longer, and the pulse wave propagation time with relatively high accuracy is obtained. Is obtained.

[0005]

However, when an electrocardiographic lead device is used as the first pulse wave detecting device, the second pulse wave detecting device detects the predetermined portion of the electrocardiographic lead waveform, and then the second pulse wave detecting device. Since the time difference until the predetermined part of the wave is detected includes the pre-ejection time from the start of the systole of the heart until the aortic valve is opened and the blood pressure is actually discharged, the pulse wave propagation time is obtained. For this purpose, it is necessary to subtract the pre-ejection time from the time difference, but since it is not easy to directly determine the pre-ejection time, the pre-ejection time subtracted from the time difference is a fixed value determined in advance based on experiments. It is often said. However, in practice, the pre-ejection time fluctuates reflecting the state of the myocardium and the degree of tightness of the peripheral arteries. The accuracy of the pulse wave transit time measured by the device used as the detection device was not yet sufficient.

When a device other than the electrocardiographic device is used as the first pulse wave detecting device, the pulse wave transit time is not affected by the fluctuation of the pre-ejection time. In some cases, a predetermined portion (a rising point, a peak, or the like) of a pulse wave to be detected cannot be accurately detected due to noise or the like, so that a highly accurate pulse wave propagation time cannot be obtained.

On the other hand, the ejection time ET, which is the contraction time of the left ventricle,
Can be calculated as a time difference from a rising point of an arterial wave such as a carotid artery wave to a notch (also called a notch) as shown in FIG. This is because the rising point of the arterial wave is generated when the aortic valve is opened and the ejection of blood from the heart is started, and the notch is generated when the aortic valve is closed. However, as described above, the rising point and the notch of the pulse wave may not be accurately detected, and the accuracy of the ejection time ET is insufficient. Further, as shown in Equation 1, the pre-ejection time PEP is obtained by subtracting the ejection time ET from the QII time from the detection of the Q wave of the electrocardiographic lead waveform to the detection of the second heart sound II. Although it can be calculated indirectly, because the accuracy of the ejection time ET is insufficient, the pre-ejection time PEP calculated in this way is
The accuracy of was also insufficient.

(Equation 1) PEP = QII-ET

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pulse wave transit time measuring apparatus capable of measuring a pulse wave transit time with high accuracy and a left ventricular contraction with high accuracy. An object of the present invention is to provide a left ventricular systolic time measuring device capable of measuring time.

[0010]

The inventor of the present invention has conducted various studies in view of the above circumstances, and as a result, since the rising point of the second heart sound II generated with the closing of the aortic valve can be detected accurately, If the rising point of the two heart sounds II is used as the upstream base point for calculating the pulse wave transit time, the upstream base point can be accurately determined, and the calculated pulse wave transit time DT is calculated based on the pre-ejection time PEP. We found that we were not affected by fluctuations.

Second heart sound generated with closure of aortic valve
When the rising point of II is used as the upstream base point, it is necessary to detect the notch of the arterial wave as the downstream base point. However, since the notch is a part of the arterial wave, it may not be possible to detect it accurately as described above.In particular, the notch is a point at which the amplitude that tends to decrease after the maximum pulse wave amplitude turns to increase, that is, the minimum value. The notch is determined, but the degree of increase may not be so large, for example, as in the brachial artery wave illustrated in FIG. In that case, there is a case where there is an error between the determined notch and the correct notch, which is larger than an error at another portion such as a rising point. Therefore, the present inventors have further studied and
If the notch cannot be determined accurately, a plurality of notch candidates are set, and a plurality of pulse wave transit time candidates DT (C) calculated between the plurality of notch candidates and the second heart sound II are determined by electrocardiography. The pulse wave transit time candidate D closest to the reference pulse wave transit time DT (R) is compared with the reference pulse wave transit time DT (R) calculated based on the waveform and the rising point of the arterial wave.
It has been found that if T (C) is determined as the normal pulse wave transit time DT (E), a highly accurate pulse wave transit time DT can be obtained. Further, it has been found that if the left ventricular contraction time STI is calculated using the notch candidates used in the calculation of the normal pulse wave propagation time DT (E), a highly accurate left ventricular contraction time STI can be obtained. . The present invention has been made based on such findings.

[0012]

First, the gist of the first invention of the present invention is to measure a pulse wave propagation time for a pulse wave to propagate between two predetermined portions of a living body. A time measuring device, (a) an electrocardiographic lead device that detects an electrocardiographic lead waveform of the living body through an electrode that is in contact with the living body, and (b) attached to the living body and propagated in an artery of the living body. (C) a second pulse wave that is attached to the living body at a site different from the first pulse wave detecting device and that propagates through an artery of the living body. A second pulse wave detecting device to be detected, and (d) a predetermined portion of the first pulse wave is detected by the first pulse wave detecting device after a waveform representing an excitation of a ventricular muscle is detected by the electrocardiographic guiding device. First up to
A first time difference calculating means for calculating a time difference, and (e) a predetermined portion of the second pulse wave is detected by the second pulse wave detecting device after the waveform indicating the excitation of the ventricular muscle is detected by the electrocardiographic guiding device. A second time difference calculating means for calculating a second time difference until the first time difference, and (f) a first time difference calculated by the first time difference calculating means.
The time difference, the tentative pre-ejection time, and the first pulse wave propagating from the heart of the living body to the site where the first pulse wave detection device is mounted.
The second pulse wave detecting device is mounted from a first equation representing a relationship with a pulse wave propagation velocity, a second time difference calculated by the second time difference calculating means, a provisional pre-ejection time, and the heart of the living body. And a third equation representing the relationship between the first pulse wave propagation velocity and the second pulse wave propagation velocity. A temporary ejection time calculating means for calculating the temporary ejection time based on the actual first time difference and the second time difference; and (g) a waveform representing ventricular muscle excitation is detected by the electrocardiograph. A third time difference calculating means for calculating a third time difference from when the first pulse wave detecting device detects a rising point of the first pulse wave, and (h) a third time difference calculating means for calculating the third time difference. From the third time difference, the temporary pre-ejection time calculated by the temporary pre-ejection time calculation means (I) candidate determining means for determining a plurality of notch candidates from the first pulse wave detected by the first pulse wave detecting device. (J) a heart sound microphone attached to the living body and detecting a heart sound of the living body, (k)
Pulse wave propagation time candidates from the time when the rising point of the second heart sound is detected by the heart sound microphone to the time when the notch candidate determined by the candidate determining means is generated are calculated for each of the plurality of notch candidates. A pulse transit time candidate calculating means, and (l) a reference pulse wave transit time calculated by the reference pulse wave transit time calculating means, among a plurality of pulse wave transit time candidates calculated by the pulse wave transit time candidate calculating means. And a means for determining a normal pulse wave transit time as the normal pulse wave transit time.

[0013]

In this way, the reference pulse wave transit time is calculated as follows. That is, the first time difference calculating means calculates a first time difference from when the electrocardiographic device detects a waveform representing the excitation of the ventricular muscle to when a predetermined portion of the first pulse wave is detected, and calculates the second time difference. The calculating means calculates a second time difference from when the electrocardiographic induction device detects a waveform representing the excitation of the ventricular muscle to when a predetermined portion of the second pulse wave is detected, and the provisional precursor ejection time calculating means calculates A first equation representing the relationship between the first time difference, the tentative pre-ejection time, and the first pulse wave velocity, and a second equation representing the relationship between the second time difference, the tentative pre-ejection time, and the second pulse wave velocity. From the equation and the third equation representing the relationship between the first pulse wave velocity and the second pulse wave velocity, the preliminary ejection time is calculated based on the first time difference and the second time difference actually calculated. ,
The third time difference calculating means calculates a third time difference from when the waveform representing the excitation of the ventricular muscle is detected to when the rising point of the first pulse wave is detected, and the reference pulse wave propagation time calculating means calculates the third time difference. The reference pulse wave transit time is calculated by subtracting the tentative pre-ejection time from the three-hour difference. In this manner, the provisional pre-ejection time fluctuates reflecting the activity state of the myocardium and the like, and the reference pulse wave transit time is relatively high in accuracy because the provisional pre-ejection time is subtracted. Then, the pulse wave propagation time candidate calculation means calculates the pulse wave propagation time candidates from the time when the rising point of the second heart sound occurs to the time when the notch candidate determined by the candidate determination means occurs for each of the plurality of notch candidates. The calculated pulse wave transit time is determined by the normal pulse wave transit time determining means from the plurality of pulse wave transit time candidates to the pulse wave transit time closest to the reference pulse wave transit time. Is obtained.

[0014]

A second aspect of the present invention to achieve the above object is a left ventricle contraction time measuring device for measuring a contraction time of a left ventricle of a living body. A pulse wave transit time measuring apparatus according to the first invention, and a positive notch determination for determining a notch candidate used for calculating a normal pulse wave transit time determined by the normal pulse wave transit time determining means as a positive notch. Means for determining an ejection time from a point in time when the rising point of the first pulse wave is detected by the first pulse wave detection device to a point in time when a positive notch determined by the positive notch determination means is detected. Exit time determination means.

[0015]

According to this configuration, the notch candidate used for calculating the normal pulse wave propagation time is determined to be a positive notch by the normal notch determining means, and the first notch is determined by the ejection period determining means. From the time when the rising point of the pulse wave is detected,
Since the ejection time is determined until the time when the correct notch is detected, it is possible to obtain a highly accurate ejection time.

[0016]

In another preferred embodiment of the second invention, preferably, the left ventricular systolic time measuring device uses the heart sound microphone from the time when the electrocardiographic lead device detects the Q wave of the electrocardiographic lead waveform. A QII time calculating means for calculating a QII time until a rising point of two heart sounds is detected, and an ejection time determined by the ejection time determining means from the QII time calculated by the QII time calculating means. And a means for calculating a pre-ejection time by subtracting the pre-ejection time. With this configuration, the precursor ejection time is calculated by the precursor ejection time calculating means by subtracting the highly accurate ejection time determined by the ejection time determining means from the QII time calculated by the QII time calculating means. Therefore, a highly accurate precursor ejection time can be obtained.

[0017]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is a block diagram illustrating a configuration of a left ventricular systolic time measuring device 10 to which the present invention is applied and also functions as a pulse wave transit time measuring device. The left ventricular contraction time measuring device 10 is measured in a state where the subject is lying on his back.

In FIG. 2, an electrocardiographic lead-in device 12 continuously detects an electrocardiographic lead, which is a so-called electrocardiogram, showing the action potential of the myocardium via a pair of limb electrodes 14 attached to the right and left wrists of a living body. And a signal S indicating the electrocardiographic wave
E is supplied to the electronic control unit 16. Since the electrocardiographic wave indicates the activity of the myocardium of the living body, it represents a pulse wave at the most upstream part of the arterial flow. When a pair of limb electrodes 14 attached to the left and right wrists is used as an electrocardiogram electrode as in the present embodiment, an electrocardiogram by the first lead is obtained. The limb electrode 14 includes an electrode plate that is brought into contact with a living body, a band that is wound around a wrist and fixes the electrode plate to a wrist, and a lead wire that electrically connects the electrode plate and the electrocardiographic lead device 12. It is comprised including.

The heart sound microphone 18 has a relatively heavy weight of several hundred grams, and has an apex, a fourth intercostal sternum left edge, a second intercostal sternum left edge, a second
It is placed at a predetermined heart sound detection site located directly above the right edge of the intercostal sternum and the right edge of the fourth intercostal sternum, and detects the heart sound of the subject. The heart sound microphone 18 is configured to detect a heart sound by, for example, an air conduction type, and outputs a heart sound signal SH representing the heart sound to the filter 20 and the A / D converter 2.
2, and output to the electronic control unit 16 via an amplifier (not shown).

The filter 20 includes four types of filters (not shown), and the four types of filters are switched as needed to attenuate the low-frequency component of the heart sound signal SH and reduce the high-frequency component so as to approximate human hearing. Emphasize.

A carotid artery wave detecting device 24 functioning as a first pulse wave detecting device is equipped with a carotid artery wave sensor 26 and is attached to the neck, and is configured, for example, as shown in detail in FIG. I have. The carotid wave detection device 24 shown in FIG.
Corresponds to Japanese Patent Application No. 10-233843 filed earlier by the present applicant.
The holding device 28 is attached so that the pressing surface 30 located at the center of the carotid artery wave sensor 26 presses the carotid artery. And the carotid artery wave sensor 26
Detects a carotid artery wave as a first pulse wave, and outputs a carotid artery signal (that is, a first pulse wave signal) SM ₁ indicating the carotid artery wave via the A / D converter 32 to the electronic control unit 16. Output to

The second pulse wave detecting device 34 is configured in the same manner as a device for measuring blood pressure, has a rubber bag in a cloth band-shaped bag, and is wound around, for example, the upper arm of a person to be measured. The cuff 36 includes a pressure sensor 40, a switching valve 42, and an air pump 44 connected to the cuff 36 via a pipe 38. The switching valve 42 has three states: a pressure supply state in which the supply of pressure into the cuff 36 is allowed, a slow discharge state in which the cuff 36 is gradually discharged, and a rapid discharge state in which the cuff 36 is rapidly discharged. It is configured to be switchable between two states.

The pressure sensor 40 detects the pressure in the cuff 36 and outputs a pressure signal SP representing the pressure to the static pressure discriminating circuit 46.
And the pulse wave discrimination circuit 48. The static pressure discriminating circuit 46 includes a low-pass filter, and a cuff pressure signal S representing a steady pressure included in the pressure signal SP, that is, a cuff pressure.
K is discriminated and the cuff pressure signal SK is supplied to the electronic control unit 16 via the A / D converter 50.

The pulse wave discriminating circuit 48 includes a band-pass filter, and frequency-discriminates a brachial artery wave signal (ie, a second pulse wave signal) SM ₂ which is a vibration component of the pressure signal SP, and converts the brachial artery wave signal SM. ₂ is supplied to the electronic control unit 16 via the A / D converter 52.

The electronic control unit 16 includes a CPU 54, R
The microcomputer 54 includes a so-called microcomputer having an OM 56, a RAM 58, and an I / O port (not shown). The CPU 54 processes the signal of the pressure signal SP while utilizing the storage function of the RAM 58 according to a program stored in the ROM 56 in advance. Is executed, a drive signal is output from the I / O port and the switching valve 42 and the air pump 4
4 and the electrocardiogram lead signal SH and the heart sound signal S
H, by processing the carotid artery signal SM ₁ and the brachial artery signal SM ₂ , the pulse wave propagation time DT and the pre-ejection time PEP
And the ejection time ET are calculated, and the calculated pulse wave propagation time DT, pre-ejection time PEP, and ejection time ET are displayed on the display 60.

FIG. 4 is a functional block diagram for explaining a main control function of the electronic control unit 16. In the figure, the first time difference calculating means 70 performs the first time difference calculation from the detection of the waveform of the excitation of the ventricular muscle by the electrocardiograph 12 to the detection of a predetermined portion of the carotid wave by the carotid wave detection device 24. One hour difference is calculated. Since there are Q waves, R waves and S waves as waveforms representing myocardial excitation in the electrocardiographic lead waveform, these Q points are used as base points on the electrocardiographic lead side.
Any of a wave, an R wave, and an S wave is used. Further, it is preferable to use a part that can be detected relatively accurately (for example, a peak (maximum amplitude point) or a rising point) as the part on the carotid artery wave side. So, for example,
The first time difference calculating means 70 calculates the time from when the Q wave of the electrocardiographic lead waveform is detected to when the rising point of the carotid artery wave is detected as the first time difference ΔT ₁ . ΔT shown in FIG.
₁ indicates the first time difference in this case.

The second time difference calculating means 72 calculates the first time difference Δ
T₁Electrocardiogram (ie, Q wave, R
Wave or S-wave) is detected,
First time difference ΔT₁Part of carotid artery wave used for calculation of
Until a predetermined part of the brachial artery wave corresponding to the position is detected.
Second time difference ΔT_TwoIs calculated. For example, the carotid artery wave
The rising point of the brachial artery wave corresponds to the rising point
Then, the second time difference calculating means 72 outputs, for example,
Starting point of carotid artery wave from the point when Q-shaped wave is detected
Is detected by the second time difference ΔT_TwoIs calculated as
ΔT shown in FIG. _TwoIndicates the second time difference in this case.
You.

The provisional pre-ejection time calculating means 74 calculates
Calculated by the first time difference calculating means 70 using Equation 4.
First time difference ΔT₁And the second time difference calculating means 72
Second time difference ΔT calculated from_TwoEquation 2 or Equation 3
To calculate the tentative pre-ejection time PEP '.
You. Note that in Equations 2 and 3, L₁Is the heart
Of the first pulse wave detecting device, ie, the carotid artery wave detecting device
Distance to place, L_TwoOf the second pulse wave detection device 34 from the heart
By the distance to the mounting site (ie, the mounting site of the cuff 36)
Yes, both are constants previously determined based on experiments.
You. Also, PWV ₁Is L₁First pulse wave with pulse wave propagating between
Means propagation speed, PWV_TwoIs L_TwoPulse wave propagates between
It means the second pulse wave propagation velocity. Further, k in Equation 4 is
The installation site of the first pulse wave detection device and the installation site of the second pulse wave detection device
When the attachment site is determined, PWV₁And PWV_TwoRelationship with
Are almost proportional to each other.
The first pulse is determined as in the present embodiment.
The attachment site of the wave detection device is the neck, and the second pulse wave detection device
If the wearing part is the upper arm, the range of 1 ≤ k ≤ 1.1
It will be an enclosure. After all, in Equations 2 to 4, the unknown
Is the tentative pre-ejection period PEP ', the first pulse wave propagation velocity PWV₁
And second pulse wave propagation velocity PWV_TwoAnd the relational expression
, The provisional pre-ejection period PEP 'is determined
Can be

(Equation 2) ΔT ₁ = PEP ′ + L ₁ / PWV ₁ (Equation 3) ΔT ₂ = PEP ′ + L ₂ / PWV ₂ (Equation 4) PWV ₁ = kPWV ₂

The provisional pre-ejection period P thus obtained
EP ′ fluctuates due to fluctuations of the first time difference ΔT ₁ and the second time difference ΔT ₂ . That is, the accuracy is relatively high because the value fluctuates while reflecting the activity state of the myocardium. However, the constant L ₁
Since L ₂ can not be measured directly, it does not exactly match the distance in the actual measurement. Further, since the constant k is also an approximate value, the accuracy is insufficient when a highly accurate pre-ejection period PEP is required.

The third time difference calculating means 76 calculates the first time difference Δ
T₁Electrocardiogram (ie, Q wave, R
Wave and / or S-wave)
The rising point of the carotid artery wave is detected by the pulse wave detection device 24
Time difference ΔT until _ThreeIs calculated. This third time
Third time difference ΔT calculated by time difference calculating means 76_ThreeHeart of
The base point on the electric induction waveform side is the first time difference ΔT₁Same as the base point of
, The first time difference ΔT₁At the carotid artery wave side
If the fixed point is the rising point, the first time difference Δ
T₁And the third time difference ΔT_ThreeIs the same. This third time difference
ΔT_ThreeIs the pre-ejection time PEP, the aortic valve opens and the blood
Of the carotid artery wave detection device 24 since the ejection of
And a pulse wave propagation time DT during which the pulse wave propagates to the position.

The reference pulse wave transit time calculating means 78 subtracts the temporary pre-ejection time PEP 'calculated by the temporary pre-ejection time calculating means 74 from the third time difference ΔT ₃ calculated by the third time difference calculating means 76. , The reference pulse wave propagation time DT (R) is calculated. The reference pulse wave propagation time DT (R) calculated in this manner cannot calculate the pre-ejection time PEP directly. Therefore, by subtracting the tentative pre-ejection time PEP ′ from the third time difference ΔT ₃ , The calculation is performed as a substitute for the pulse wave propagation time DT during which the pulse wave propagates to the site where the carotid wave detection device 24 is mounted. But,
As described above, since the provisional pre-ejection time PEP is relatively accurate, the reference pulse wave transit time DT (R) calculated by the reference pulse wave transit time calculation means 78 is also relatively accurate.

The candidate deciding means 80 includes the carotid artery wave detecting device 2
4, a plurality of notch candidates are determined from the carotid artery wave detected. For example, based on the carotid pulse wave signal SM ₁ which is successively supplied from the carotid pulse wave detecting apparatus 24, the preset predetermined time period after the maximum pulse wave amplitude for each one heartbeat is determined, all showing the minimum value Is determined as a notch candidate.
FIG. 5 is an example of a carotid artery wave enlarged near the notch,
In the case of the pulse wave shown in FIG. 5, three notch candidates 1 to 3 are determined.

The pulse wave propagation time candidate calculating means 82 calculates a time difference, that is, a pulse difference from the time when the rising point of the second heart sound II is detected by the heart sound microphone 18 to the time when the notch candidate determined by the candidate determining means 80 is generated. A wave propagation time candidate DT (C) is calculated for each of the plurality of notch candidates.

The normal pulse wave transit time determining means 84 includes a plurality of pulse wave transit time candidate DT (C) calculated by the pulse wave transit time candidate calculating means 82 and the reference pulse wave transit time calculating means 78.
Is compared with the reference pulse wave transit time DT (R) calculated by the above, and the pulse wave transit time candidate DT closest to the reference pulse wave transit time DT (R) among the plurality of pulse wave transit time candidates DT (C).
(C) is determined as the normal pulse wave propagation time DT (E). Since the reference pulse wave transit time DT (R) is relatively accurate as described above, it is relatively close to an accurate pulse wave transit time or an ideal pulse wave transit time, but still contains a slight error. . On the other hand, as described in the description of the candidate determining means 80, the error between the plurality of notch candidates is based on the part used for calculating the reference pulse wave transit time DT (R) such as the rising point of the pulse wave. May be large, the reference pulse wave transit time DT (R) is included in the plurality of pulse wave transit time candidates DT (C).
Although one of the plurality of notch candidates is larger than the error, any one of the plurality of notch candidates is a correct notch, that is, a positive notch, and the pulse wave transit time candidate DT (DT () calculated based on the positive notch and the second heart sound II) C) is the reference pulse wave transit time D
Since the pulse wave transit time is closer to the accurate pulse wave transit time than T (R), the normal pulse wave transit time DT (E) determined by the normal pulse wave transit time determination means 84 is more accurate than the reference pulse wave propagation DT (R). That's it.

The correct notch determining means 86 determines a notch candidate used for calculating the normal pulse wave propagation time DT (E) as a correct notch. As shown in FIG. 1, the ejection time determining means 88 detects the positive notch determined by the positive notch determining means 86 after the carotid artery wave detecting device 24 detects the rising point of the carotid artery wave. The time up to the time is calculated as the ejection time ET.

The QII time calculating means 90 is provided by the electrocardiograph 1
The QII time from when the Q wave of the electrocardiographic lead waveform is detected by step 2 to when the rising point of the second heart sound II is detected by the heart sound microphone 18 is calculated.

The pre-ejection time calculation means 92 subtracts the ejection time ET determined by the ejection time determination means 88 from the QII time calculated by the QII time calculation means 90, ie, Departure time PEP
Is calculated. Q calculated by the QII time calculation means 90
The II time is a time in which the time from the start of the activity of the myocardium to the closing of the aortic valve is directly calculated accurately, and the ejection time ET calculated by the ejection time calculating means 88 is the time when the aortic valve is opened Since the time from the start to the closing is accurately determined, the pre-ejection time PEP calculated by the pre-ejection time calculation means 92 also has high accuracy.

FIG. 6 is a flowchart for explaining a main part of the control operation of the electronic control unit 16. In the figure,
First, in step S1 (hereinafter, steps are omitted), it is determined whether or not the Q wave of the electrocardiographic lead waveform is detected based on the electrocardiographic lead signal SE sequentially supplied from the electrocardiographic lead device 12. You. When this determination is denied, S1 is repeated, but when affirmed, the detection time of the Q wave is stored in a predetermined storage area of the RAM 58 in S2.

[0040] In subsequent S3, based on the carotid pulse wave signal SM ₁ which is successively supplied from the carotid pulse wave detecting device 24, a rising point of the carotid pulse wave whether or not it is detected is determined. If this determination is denied, the determination in S3 is repeated, but if affirmative, in S4, the detection time of the rising point of the carotid artery wave is stored in a predetermined storage area of the RAM 58.

Further, in the following S5, the pulse wave discrimination circuit 48
From the brachial artery wave signal SM ₂ sequentially supplied from
It is determined whether a rising point of the brachial artery wave has been detected. If this determination is denied, the determination in S5 is repeated, but if affirmative, in S6, the detection time of the rising point of the brachial artery wave is stored in a predetermined storage area of the RAM 58.

In S7 corresponding to the first time difference calculating means 70 and the third time difference calculating means 76, the Q of the electrocardiographic lead waveform stored in S2 is calculated from the detection time of the rising point of the carotid artery wave stored in S4. The first time difference ΔT ₁ is calculated by subtracting the wave detection time. Since the first time difference ΔT ₁ is a time difference from the Q wave of the electrocardiographic lead waveform to the rising point of the carotid artery wave, the third time difference ΔT 1
It is also used as a T _3.

S corresponding to the following second time difference calculating means 72
At 8, the second time difference ΔT ₂ is obtained by subtracting the detection time of the Q wave of the electrocardiographic lead waveform stored at S2 from the detection time of the rising point of the brachial artery wave stored at S6.
Is calculated.

At S9 corresponding to the tentative pre-ejection time calculating means 74, the first calculated at S7 to S8 is performed.
The time difference ΔT ₁ and the second time difference ΔT ₂ are substituted into the above formulas 2 and 3, and from the formulas 2 and 3 and the formula 4,
The provisional pre-ejection period PEP 'is calculated.

The step S10 corresponds to a subsequent reference pulse wave propagation time calculation means 78, from the third time difference [Delta] T ₃ calculated in S7, by the temporary pre-ejection period which is calculated in S9 PEP 'is subtracted, reference pulse The wave propagation time DT (R) is calculated.

Further, in the following S11, it is determined whether or not the rising point of the second heart sound II has been detected based on the heart sound signal SH sequentially supplied from the heart sound microphone 18. If this determination is denied, the determination in S11 is repeated, but if affirmative, in S12, the detection time of the rising point of the second heart sound II is stored in a predetermined storage area of the RAM 58.

Then, in S13 corresponding to the subsequent candidate determining means 80, the minimum value is set in a predetermined period (for example, 0.1 to 0.2 seconds) after the second heart sound II is detected in S11. By this determination, for example, three portions 1 to 3 shown in FIG. 5 are determined as notch candidates, and the time when these notch candidates are detected is RA.
It is stored in a predetermined storage area of M58.

Subsequently, at S14 corresponding to the pulse wave transit time candidate calculating means 82, the time when the rising point of the second heart sound II stored at S12 is detected and the notch candidate determined at S13 are detected. A time difference between the time points, ie, the pulse wave propagation time candidates DT (C) are calculated for all the notch candidates. Then, in S15 corresponding to the subsequent normal pulse wave propagation time determining means 84, of the plurality of pulse wave propagation time candidates DT (C) calculated in S14, the reference pulse wave propagation time DT calculated in S10. The pulse wave propagation time DT (E) closest to (R) is determined.

S1 corresponding to the following positive notch determination means 86
6, the normal pulse wave propagation time DT determined in S15
The notch candidate used for calculating (E) is determined to be a positive notch, and in S17 corresponding to the ejection time determination means 88, the time when the positive notch occurs and the time in S4
Is determined as the ejection time ET.

At S18 corresponding to the QII time calculation means 90, the detection time of the Q wave of the electrocardiographic lead waveform stored at S2 and the detection time of the rising point of the second heart sound II stored at S12 are calculated. Is calculated as the QII time, and S1 corresponding to the following pre-ejection time calculating means 92
In step 9, based on the QII time calculated in step S18 and the ejection time ET determined in step S17, the pre-ejection time PEP is calculated from equation (1).

As described above, according to this embodiment, first,
The reference pulse wave transit time DT (R) is calculated as follows. That is, after the first time difference calculating means 70 (S7) detects the Q wave by the electrocardiographic lead-in device 12,
The first time difference ΔT ₁ until the rising point of the carotid artery wave is detected is calculated, and after the Q wave is detected by the electrocardiograph 12 by the second time difference calculating means 72 (S 8), the brachial artery wave is detected. The second until the rising point is detected
The time difference ΔT ₂ is calculated, and the preliminary precursor discharge time calculating means 74
According to (S9), the mathematical expression 2 representing the relationship between the first time difference ΔT ₁ , the tentative pre-ejection time PEP ′, and the first pulse wave propagation velocity PWV ₁ , the second time difference ΔT ₂ , the tentative pre-ejection time PEP ′, Equation 3 representing the relationship between the two pulse wave propagation velocities PWV ₂ and the first pulse wave propagation velocity PWV ₁ and the second pulse wave propagation velocity PWV
_From Equation 4 that expresses the relationship to
The provisional pre-ejection time PEP ′ is calculated based on the time difference ΔT ₁ and the second time difference ΔT ₂ , and the third time difference calculating unit 76
By (S7), the third time difference ΔT ₃ from when the Q wave of the electrocardiographic lead waveform is detected to when the rising point of the carotid artery wave is detected is calculated, and the reference pulse wave transit time calculating means 78 (S7)
10), the reference pulse wave propagation time D is obtained by subtracting the provisional pre-ejection time PEP ′ from the third time difference ΔT _3.
T (R) is calculated. Then, the pulse wave propagation time candidate calculating means 82 (S14) performs the pulse wave propagation from the time when the rising point of the second heart sound II occurs to the time when the notch candidate determined by the candidate determining means 80 (S13) occurs. The time candidate DT (C) is calculated for each of the notch candidates, and the normal pulse wave propagation time determining means 84 (S15)
From the plurality of pulse wave transit time candidates DT (C), the closest pulse wave transit time DT (R) is determined as the normal pulse wave transit time DT (E). Propagation time is obtained.

Further, according to the present embodiment, the notch candidate used for calculating the normal pulse wave propagation time DT (E) is determined as the normal notch by the normal notch determination means 86 (S16), and is ejected. Since the period determining means 88 (S17) determines the ejection time ET from the time when the rising point of the carotid artery wave is detected to the time when the positive notch is detected, the ejection time ET with high accuracy is determined. Obtainable.

According to the present embodiment, the QII time calculating means 90 (S19) is used by the precursor ejection time calculating means 92 (S19).
Since the pre-ejection time PEP is calculated by subtracting the high-precision ejection time ET determined by the ejection time determination means 88 (S17) from the QII time calculated in 18), the high-precision pre-ejection time is obtained. PEP can be obtained.

Although the embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above-described embodiment, the carotid artery wave is used as the first pulse wave and the brachial artery wave is used as the second pulse wave. However, the first pulse wave and the second pulse wave are It is not limited to the example. For example, a brachial artery wave may be used as the first pulse wave, and a peripheral pulse wave at the fingertip may be used as the second pulse wave. Further, the first pulse wave does not need to be a part closer to the heart than the second pulse wave. For example, even if the brachial artery wave is used as the first pulse wave and the carotid artery wave is used as the second pulse wave Good. In short, the first pulse wave and the second pulse wave may be pulse waves at two different portions downstream of the heart.

In the above-described embodiment, the electrocardiograph 1
2, the electrocardiogram was measured by the first lead of the bipolar limb lead method via the electrodes 14 attached to the right and left wrists. The electrocardiogram may be measured by three leads, or the electrocardiogram may be measured by a unipolar limb lead method or a unipolar chest lead method.

In the above embodiment, the heart sound microphone 18 is an air conduction type microphone, but other types of heart sound microphones such as a direct conduction displacement type or a direct conduction acceleration type may be used. .

Further, using the normal pulse wave propagation time DT (E) calculated in the above embodiment, the pulse wave propagation velocity PWV
May be calculated.

In addition, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an electrocardiogram, an electrocardiogram, a carotid artery wave, and a brachial artery wave for one beat.

FIG. 2 is a block diagram showing a configuration of a left ventricular systolic time measuring apparatus according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating in detail a carotid artery wave detection device according to the embodiment of FIG. 2;

FIG. 4 is a functional block diagram for explaining a main part of a control function of the electronic control device according to the embodiment of FIG. 2;

FIG. 5 is an enlarged view showing the vicinity of a carotid artery notch in order to explain a notch candidate determined by the candidate determining means of FIG. 4;

FIG. 6 is a flowchart illustrating a main part of a control operation of the electronic control device of FIG. 2;

[Explanation of symbols]

 10: Left ventricular systolic time measuring device 12: Electrocardiographic guiding device 18: Heart sound microphone 24: Carotid artery wave detecting device (first pulse wave detecting device) 34: Second pulse wave detecting device 70: First time difference calculating means 72: Second time difference calculating means 74: Temporary pre-ejection time calculating means 76: Third time difference calculating means 78: Reference pulse wave transit time calculating means 80: Candidate determining means 82: Pulse wave transit time candidate calculating means 84: Normal pulse wave transit time Determining means 86: correct notch determining means 88: ejection time determining means 90: QII time calculating means 92: pre-ejection time calculating means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-11-113860 (JP, A) JP-B-57-6930 (JP, B2) JP-B-62-42612 (JP, B2) (58) Field (Int.Cl. ⁷ , DB name) A61B 5/0245

Claims (3)

(57) [Claims] 1. A pulse wave transit time measuring device for measuring a pulse wave transit time in which a pulse wave propagates between two predetermined portions of a living body, wherein an electrocardiographically induced waveform of the living body is passed through an electrode contacting the living body. An electrocardiographic induction device that detects a first pulse wave that is attached to the living body and detects a first pulse wave that propagates in an artery of the living body; and at a site different from the first pulse wave detecting device. A second pulse wave detection device that is attached to the living body and detects a second pulse wave that propagates in an artery of the living body; and a first waveform after the electrocardiographic lead device detects a waveform representing ventricular muscle excitation. A first time difference calculating means for calculating a first time difference until a predetermined portion of the first pulse wave is detected by the pulse wave detecting device; and a waveform representing the excitation of the ventricular muscle is detected by the electrocardiographic lead device, Until a predetermined portion of the second pulse wave is detected by the second pulse wave detection device. A second time difference calculating means for calculating a second time difference, a first time difference calculated by the first time difference calculating means, a tentative pre-ejection time, and a portion of the living body where the first pulse wave detecting device is mounted. A first equation representing the relationship between the first pulse wave propagation velocity at which the pulse wave propagates up to, the second time difference calculated by the second time difference calculation means, the provisional pre-ejection time, and the heart of the living body. A second equation representing the relationship between the second pulse wave velocity and the second pulse wave velocity at which the pulse wave propagates to the site where the second pulse wave detector is mounted, and the first pulse wave velocity and the second pulse wave velocity And a third formula that represents the relationship between the first time difference and the second time difference, based on the actual first time difference and the second time difference. After the waveform indicating the excitement is detected, the first pulse wave detecting device sets up the first pulse wave. A third calculation of a third time difference until a rising point is detected
A time difference calculating means, and a reference pulse wave propagation calculating a reference pulse wave propagation time by subtracting the temporary pre-ejection time calculated by the temporary pre-ejection time calculating means from the third time difference calculated by the third time difference calculating means. Time calculating means, from a first pulse wave detected by the first pulse wave detection device,
Candidate determination means for determining a plurality of notch candidates; a heart sound microphone attached to the living body for detecting a heart sound of the living body; and a candidate determination from the time when the rising point of the second heart sound is detected by the heart sound microphone. Pulse wave transit time candidate calculating means for calculating the pulse wave transit time candidates up to the time when the notch candidate determined by the means is generated, for each of the plurality of notch candidates, and calculated by the pulse wave transit time candidate calculating means. Of the plurality of pulse wave transit time candidates, the one closest to the reference pulse wave transit time calculated by the reference pulse wave transit time calculating means is
A pulse wave transit time measuring means for determining a normal pulse wave transit time. 2. A left ventricle contraction time measuring device for measuring a contraction time of a left ventricle of a living body, wherein the pulse wave transit time measuring device is determined by the pulse wave transit time measuring device according to claim 1. A positive notch determining means for determining a notch candidate used for calculating the normal pulse wave propagation time as a positive notch, and a time when a rising point of the first pulse wave is detected by the first pulse wave detecting device. An ejection time determining means for determining an ejection time up to a point in time when the positive notch determined by the correct notch determining means is detected. 3. The method according to claim 1, wherein the step of detecting the Q wave of the electrocardiographic lead waveform by the electrocardiographic lead apparatus includes the step of:
QII time calculating means for calculating a QII time up to a time point at which a heart sound rising point is detected; and subtracting the ejection time determined by the ejection time determining means from the QII time calculated by the QII time calculating means. The left ventricle contraction time measuring device according to claim 2, further comprising a precursor ejection time calculating means for calculating a precursor ejection time.