JP3668687B2 - Pulse wave velocity measuring device and ultrasonic diagnostic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse wave velocity measuring apparatus and an ultrasonic diagnostic apparatus, and more particularly to a pulse wave velocity measuring method propagating through a blood vessel wall.
[0002]
[Prior art and problems]
Pulse wave velocity (Pulse Wave Velocity) is an excellent indicator of blood vessel properties, especially hardness. Therefore, in order to diagnose cardiovascular diseases such as arteriosclerosis, measurement of pulse wave velocity is required.
[0003]
Although the pulse wave velocity is measured by a pulse wave meter for a long time, only the average velocity of the pulse wave between the carotid artery and the femoral artery can be measured. Therefore, according to such measurement, there is a problem that local blood vessel characteristics cannot be diagnosed.
[0004]
A method of measuring the pulse wave velocity using the ultrasonic Doppler method has also been proposed. In this method, two ultrasonic beams are set in a blood vessel so as to pass through two points separated by several centimeters, and the pulse wave propagation velocity is calculated from the propagation time of blood flow flowing between the two points. However, since this method uses two probes to perform Doppler measurement at two locations simultaneously, the scale of the apparatus increases. Further, even with this conventional method, the pulse wave velocity cannot be measured for a local site of several centimeters or less.
[0005]
Japanese Patent Publication No. 7-67450, Japanese Patent No. 2801450, and Japanese Patent Application Laid-Open No. 2000-271117 disclose techniques for measuring the displacement of a blood vessel wall. Further, Japanese Patent Application Nos. 2000-032856, 2000-123615, 2000-203146, and 2000-245892, which have not been disclosed at the time of filing of this patent application, relate to the wave intensity (WI) described later. Technology is disclosed. However, none of the documents discloses the measurement of the pulse wave velocity.
[0006]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to accurately measure the local properties of blood vessels, particularly the pulse wave velocity.
[0007]
[Means for Solving the Problems]
I. Principle explanation
When attention is paid to a specific blood vessel site in the living body, there are a “forward wave” propagating from the heart to the periphery and a “reflected wave” reflected from the periphery as pulse waves propagating through the blood vessel wall at the specific site. At the local site, the changes in local blood pressure and blood flow velocity caused by the forward wave in the minute time dt are respectively expressed as dP _f , DU _f And changes in local blood pressure and blood flow velocity caused by reflected waves within a minute time dt are represented by dP _b , DU _b And
[0008]
According to the water-hammer equation that has been known for a long time in physiology and the like, the following equation holds. Where ρ is the blood density and c is the pulse wave velocity.
[0009]
[Expression 1]
dP _f = ΡcdU _f ... (1)
dP _b = -ΡcdU _b ... (2)
On the other hand, the blood pressure change dP and the blood flow velocity change dU in the local region are expressed by the following equations.
[0010]
[Expression 2]
dP = dP _f + DP _b ... (3)
dU = dU _f + DU _b ... (4)
If a change in blood flow and a change in blood pressure at a certain time are caused by only a forward wave at a specific local site of a blood vessel, dP and dU are expressed as follows.
[0011]
[Equation 3]
dP = dP _f ... (5)
dU = dU _f ... (6)
The above equations (5) and (6) to (1) can be expressed as follows.
[0012]
[Expression 4]
dP = ρcdU (7)
From this equation (7), the pulse wave propagation velocity c is expressed as follows.
[0013]
[Equation 5]
c = (dP / dU) / ρ (8)
Depending on the time phase of the heartbeat, the forward wave and the reflected wave propagate in the blood vessel wall in an overlapping manner, but in such a case, if the period in which only the forward wave is dominant can be identified, the above-mentioned period is included in that period. The pulse wave velocity can be calculated from the equation (8).
[0014]
On the other hand, Wave Intensity (WI) is known as an index for evaluating the circulation dynamics of the circulatory system. The wave intensity WI can be expressed as follows when the time derivative of the blood pressure P is expressed as dP / dt and the time derivative of the blood flow velocity U is expressed as dU / dt.
[0015]
[Formula 6]
WI = (dP / dt) (dU / dt) (9)
Using dP / dt and dU / dt for this WI calculation, dP / dU in equation (8) is obtained from the following equation.
[0016]
[Expression 7]
dP / dU = (dP / dt) / (dU / dt) (10)
When the waveform of the wave intensity is observed, two positive peaks (first peak and second peak) are recognized at the initial stage and the final stage of the blood flow ejection process in the heart. A positive wave intensity means that changes in blood pressure and blood flow velocity at the local site are mainly caused by forward waves.
[0017]
Therefore, based on the waveform of the wave intensity, it is possible to specify a period in which it can be considered that only the forward wave is generated, and in the period specified as such, the value of the above expression (10) is changed to the expression (8). When substituted, the pulse wave velocity c can be calculated. The blood density ρ can be regarded as a constant value.
[0018]
In addition, since a period in which only a forward wave is generated in a certain local region occurs in synchronization with the heartbeat, the above (8) is based on biological information (for example, an electrocardiogram signal) representing a heartbeat other than the wave intensity. It is also possible to determine the period for calculating the expression.
[0019]
II. Explanation of solution
(1) In order to achieve the above object, the present invention relates to a blood flow rate calculating means for calculating a blood flow velocity for a specific part in a blood vessel, a blood pressure calculating means for calculating a blood pressure for the specific part, and the specific part. And a pulse wave velocity calculating means for calculating the pulse wave velocity for the specific part from the blood flow velocity and blood pressure.
[0020]
According to the above configuration, the local blood flow velocity and blood pressure are measured and calculated for a specific part in accordance with the principle described above, and the pulse wave propagation velocity is calculated using them. The measurement object can include a human body and other animals. The local blood flow velocity is preferably measured using an ultrasonic Doppler method, but other measurement methods can also be used. For local blood pressure measurement, it is desirable to use a sphygmomanometer and an ultrasonic displacement measurement method, but other measurement methods can also be used.
[0021]
By the way, ultrasonic measurement may be performed from outside the body using an ultrasonic probe, or a catheter-type ultrasonic probe is inserted into a blood vessel so that local blood flow velocity and blood pressure can be measured. You may make it measure. Further, in the above explanation of the principle, each calculation of blood flow velocity time differentiation and blood pressure time differentiation was shown. However, in the hardware calculation and the software calculation for that purpose, the pulse directly from the blood flow velocity and the blood pressure is shown. It is also possible to determine the wave propagation velocity. Furthermore, in the above description of the principle, the pulse wave velocity is calculated within a specific calculation period. However, the pulse wave velocity may be effectively calculated even outside such a calculation period. . For example, if the calculation results of individual time phases are displayed, it can be evaluated whether the determination of the calculation period is appropriate. It is also conceivable to calculate the pulse wave velocity for the reflected wave instead of the forward wave.
[0022]
(2) Desirably, it includes first differential calculation means for calculating a time derivative of the blood flow velocity, and second differential calculation means for calculating a time derivative of the blood pressure, It is calculated from the time derivative of the flow velocity and the time derivative of the blood pressure. Desirably, it includes period determining means for determining a calculation period based on a heartbeat cycle, and the pulse wave propagation velocity is calculated within the calculation period.
[0023]
Preferably, the period determination unit determines the calculation period based on predetermined biological information whose value varies according to a heartbeat cycle. The biological information may be information that can directly or indirectly determine the period in which the forward wave is dominant.
[0024]
For example, the following WIn can be given as an index similar to the wave intensity. Here, D is the blood vessel diameter.
[0025]
[Equation 8]
WIn = [(1 / D) (dD / dt)] (dU / dt) (11)
According to the research of the present inventor, it has been confirmed that the above WIn is an index having a property equivalent to that of the wave intensity, and the WIn can be referred to as the second wave intensity. It is also possible to specify a period in which the forward wave is dominant based on such an index.
[0026]
(3) Preferably, the predetermined biological information is a wave intensity which is an index for evaluating the circulatory dynamics of the circulatory system. In other words, the wave intensity or the second wave intensity has a property as an indicator of the strength of the forward wave, and it is possible to determine the period in which the forward wave is dominantly generated directly from the wave intensity. is there.
[0027]
Preferably, the period determination means includes peak detection means for detecting the peak of the wave intensity, and setting means for setting the calculation period based on the peak of the wave intensity. Here, preferably, the peak detecting means detects a first peak and a second peak of the wave intensity. For example, the pulse wave propagation velocity may be calculated at the time phase of the peak apex position, the range from the peak level to a certain value may be determined as the calculation period, or the wave intensity exceeds a predetermined threshold value You may make it determine a period as a calculation period.
[0028]
Desirably, the pulse wave propagation velocity calculation means calculates an average value of the pulse wave propagation velocity within the calculation period. According to the average value, the influence of noise and the like can be reduced and the pulse wave velocity can be calculated with high accuracy.
[0029]
(4) Moreover, in order to achieve the said objective, this invention carries out the said specific | specification based on the said transmitter / receiver which transmits and receives an ultrasonic wave with respect to the specific site | part of the blood vessel, and outputs a received signal, and the said received signal A blood flow velocity calculating means for calculating a blood flow velocity in the part, a displacement calculating means for calculating a displacement of the blood vessel wall in the specific part, and a blood pressure for the specific part are calculated using the displacement of the blood vessel wall. Based on the blood pressure calculating means, the time derivative of the blood flow velocity and the time derivative of the blood pressure, the time derivative of the blood flow velocity and the time derivative of the blood pressure, And an index value calculating means for calculating an index value representing the property. Here, preferably, the index value is a velocity of a pulse wave propagating through the blood vessel wall.
[0030]
Preferably, the blood pressure calculation means calculates the blood pressure for the specific part from the displacement of the blood vessel wall using the maximum blood pressure and the minimum blood pressure of the other part measured by a sphygmomanometer as reference values. Examples of the sphygmomanometer include a cuff type sphygmomanometer that is wound around the upper arm and measures blood pressure.
[0031]
Preferably, it includes a display that simultaneously displays one or more information utilized to calculate the pulse wave velocity along with the pulse wave velocity. If the waveform display of each information is performed, the correlation between the information can be analyzed and evaluated, and it can be determined whether an appropriate calculation has been performed.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0033]
FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus. This ultrasonic diagnostic apparatus has a function of calculating a pulse wave velocity.
[0034]
In FIG. 1, the probe 10 is in contact with the surface of the living body 12. The probe 10 has an array transducer 22 inside. The array transducer 22 includes a plurality of transducer elements 22a.
[0035]
A blood vessel 14 exists inside the living body 12 at a certain distance from the body surface, and a blood flow 20 flows inside the blood vessel 14. The blood vessel 14 has a blood vessel wall 15, and the blood vessel wall is roughly divided into a front wall 16 and a rear wall 18 as viewed from the probe 10.
[0036]
By the electronic scanning control on the array transducer 22 described above, the ultrasonic beam is electronically scanned in a predetermined direction, thereby forming a two-dimensional scanning surface. In FIG. 1, the ultrasonic beam on one end side of the scanning surface is represented by reference numeral 24, and the ultrasonic beam on the other end side is represented by reference numeral 26. The electronic scanning method shown in FIG. 1 is electronic linear scanning, but the present invention can also be applied to electronic sector scanning and the like.
[0037]
In the present embodiment, the ultrasonic beam 28 for measuring the blood vessel wall displacement is set in a direction orthogonal to the central axis of the blood vessel 14 by the user setting, and Doppler measurement intersecting the ultrasonic beam 28 for measuring the blood vessel wall displacement is performed. The ultrasonic beam 30 for use is automatically set.
[0038]
Here, the ultrasonic beam 28 for measuring the blood vessel wall displacement is desirably positioned within a vertical cross section including the central axis of the blood vessel 14, and preferably two tracking gates are provided on the ultrasonic beam 28 according to user settings. 34 and 36 are set. Specifically, the tracking gate 34 is set as a region including the edge of the front wall 16, and the tracking gate 36 is set as a region including the edge of the rear wall 18. A displacement calculator 48 described later automatically tracks the edge of the blood vessel wall in these tracking gates 34 and 36, and calculates the displacement D of the blood vessel wall.
[0039]
A sample volume 32 is set on the ultrasonic beam 30 for Doppler measurement by user setting or automatic setting. When the sample volume 32 is automatically set, the sample volume 32 is set as a fixed range with the intermediate point between the two tracking gates 34 and 36 as a reference. The ultrasonic beam 30 for Doppler measurement is set in an oblique direction with respect to the ultrasonic beam 28 so as to pass through an intermediate point between the two tracking gates 34 and 36. That is, since Doppler information cannot be detected even if ultrasound is transmitted / received from a direction orthogonal to the blood flow, the Doppler measurement beam 30 is set at an angle inclined from the ultrasound beam 28 in this way. .
[0040]
Incidentally, in order to increase the calculation accuracy, when the ultrasonic beam 28 is not orthogonal to the central axis of the blood vessel 14, angle correction is performed on the displacement D calculated by the displacement calculation unit 48 described later. Also good. Further, according to the inclination angle of the Doppler measurement beam 30 with respect to the blood flow, angle correction may be performed on the average velocity U calculated by the blood flow velocity calculating unit 50 described later.
[0041]
The transmission unit 38 is a circuit that supplies a transmission signal to each vibration element constituting the array transducer 22, and a transmission beam is generated by giving a predetermined delay time to each transmission signal in the transmission unit 38. It is formed. Further, the transmission beam is electronically scanned by the action of the transmission unit 38.
[0042]
On the other hand, the receiving unit 40 is a circuit that performs so-called phasing addition on the reception signals output from the respective vibration elements constituting the array transducer 22. Specifically, a predetermined delay time is given to each reception signal, and addition is performed thereafter, thereby forming a reception beam electronically. Further, the reception beam is electronically scanned by the action of the receiving unit 40.
[0043]
When the transmission / reception direction for displacement measurement and the transmission / reception direction for Doppler measurement are set, the transmission unit 38 and the reception unit 40 respectively transmit the ultrasonic beam 28 for measuring the vascular wall displacement and the Doppler measurement for the transmission / reception direction. The transmission / reception control is performed so that the ultrasonic beam 30 is formed. In this case, the ultrasonic beam 28 for measuring the vascular wall displacement and the ultrasonic beam 30 for Doppler measurement may be alternately set, or these beams 28 may be set while performing an electronic scan of the ultrasonic beam. , 30 may be set at a predetermined period.
[0044]
Incidentally, the probe 10 is brought into contact with, for example, the neck of a human body, and the blood vessel 14 is, for example, a carotid artery. Moreover, the center frequency of the ultrasonic wave transmitted / received is 7.5 MHz, for example.
[0045]
The control unit 42 controls the overall operation of the ultrasonic diagnostic apparatus, and an operation panel 44 is connected to the control unit 42. The operation panel 44 includes switches, a keyboard, a trackball, and the like, and the user can make various settings and inputs using the operation panel 44. The control unit 42 controls the operation of each circuit in the transmission unit 38, the reception unit 40, and other devices based on such settings. Incidentally, as shown in FIG. 1, a blood pressure monitor 200 is provided.
[0046]
The ultrasonic image forming unit 46 forms a tomographic image (B-mode image), an M-mode image, or other ultrasonic image in the living body based on the received signal after phasing addition output from the receiving unit 40. Circuit. The image data of the ultrasonic image thus formed is output to the display processing unit 52.
[0047]
The displacement calculation unit 48 is a circuit that calculates the diameter D of the blood vessel 14 based on the received signal (echo data) obtained on the ultrasonic beam 28 for measuring the blood vessel wall displacement shown in FIG. Specifically, the position of the front wall 16 is tracked while tracking the edge of the front wall 16 in the tracking gate 34. Similarly, the edge of the rear wall 18 is also tracked in the tracking gate 36 and the position thereof is detected. Are sequentially detected, and the distance D between the two walls 16 and 18 is calculated to calculate the diameter D of the blood vessel 14 at each time.
[0048]
Incidentally, when tracking the displacement of the blood vessel wall, tracking may be performed based on the phase of the received signal, or tracking may be performed using the amplitude of the received signal. Various known methods can be used for tracking.
[0049]
The blood flow velocity calculation unit 50 is configured by, for example, a quadrature detector or an autocorrelator, and based on the received signal (echo data) obtained on the Doppler measurement ultrasonic beam 30, specifically, This circuit calculates an average blood flow velocity U based on echo data obtained in the sample volume 32. That is, the sample volume 32 has a certain width, and various blood flow velocity components exist within the certain width, but the blood flow velocity calculation unit 50 calculates the average value of these velocity components. The average speed U is calculated as follows.
[0050]
Information on the blood flow velocity U output from the blood flow velocity calculator 50 is input to the differentiator 206, which calculates the time derivative dU / dt of the blood flow velocity. The time differential dU / dt of the blood flow velocity, which is the calculation result, is output to the WI calculation unit 210 and the pulse wave propagation velocity calculation unit 212 in this embodiment.
[0051]
On the other hand, blood pressure information 202 output from the sphygmomanometer 200 is input to the local blood pressure calculation unit 204. Here, the sphygmomanometer 200 is, for example, a cuff type sphygmomanometer that is wound around the upper arm and measures blood pressure. Information on blood vessel diameter D is input to local blood pressure calculation unit 204 together with blood pressure information 202. The local blood pressure calculation unit 204 determines the maximum blood pressure and the minimum blood pressure in each heartbeat measured by the sphygmomanometer 200, calibrates the maximum and minimum blood vessel diameters to the maximum blood pressure and the minimum blood pressure, and determines a conversion formula. Using the conversion formula, the blood pressure P of the local region that is the measurement target is calculated from the blood vessel diameter at each time. This process itself is known, but in any case, the local blood pressure P is calculated for the local region where the blood flow velocity is measured. Information on the local blood pressure P is input to the differentiator 208, and the differentiator 208 calculates the time differential dP / dt of the local blood pressure. Information of the time differential dP / dt of the local blood pressure is output to the WI calculation unit 210 and the pulse wave velocity calculation unit 212 in the present embodiment.
[0052]
In this embodiment, the WI calculation unit 210 calculates the wave intensity WI by executing the above equation (9). The information on the wave intensity WI as the calculation result is output to the pulse wave velocity calculation unit 212 and the display processing unit 52.
[0053]
The pulse wave velocity calculation unit 212 is a circuit that calculates the pulse wave velocity c according to the above equation (8). A specific circuit configuration will be described later with reference to FIGS. Information on the calculated pulse wave velocity is output to the display processing unit 52. Each configuration shown in FIG. 1 can also be configured by software as necessary.
[0054]
The display processing unit 52 functions as a scan converter and an image processing unit, and as illustrated, image data of an ultrasonic image, blood vessel diameter D data, blood flow velocity U data, pulse wave propagation velocity c. Data, wave intensity WI data, electrocardiogram signal (signal 53 from an electrocardiograph not shown), and the like. The display processing unit 52 has a function of arranging the waveforms of the respective signals on the same time axis and displaying them as a graph. The display unit 56 displays the ultrasonic image and each information as a graph. The display example will be described later with reference to FIG.
[0055]
FIG. 2 is a block diagram showing a specific circuit configuration example of the pulse wave velocity calculation unit 212 shown in FIG. The discriminator 214 functions as a calculation period setting unit, in other words, has a function of estimating a period in which the forward wave is dominant. Specifically, the information of the wave intensity WI is input to the discriminator 214, and when the value of the wave intensity WI becomes larger than a predetermined determination level K1 set in advance, the discriminator 214 Outputs the computation enable signal. As is well known, when the waveform of the wave intensity is viewed during one heartbeat, two large peaks are observed, and the discriminator 214 sets the calculation period for each peak. This will be described later with reference to FIG.
[0056]
The blood density ρ that can be regarded as a constant value is input to the calculator 216, and the pulse wave propagation velocity c is calculated in accordance with the above-described equation (8) within the calculation period set by the discriminator 214. In addition to being output to the display processing unit 52 (see FIG. 1), the information on the pulse wave velocity c calculated in this way is output to the average value calculator 218 in the present embodiment. The average value calculator 218 is a circuit that calculates the average value c ′ of the pulse wave velocity within the above calculation period. Such an average value c ′ is output to the display processing unit 52 described above.
[0057]
FIG. 3 shows another specific configuration example of the pulse wave velocity calculation unit 212 shown in FIG. In the block diagram shown in FIG. 3, the information on the wave intensity WI is temporarily stored in the memory 222 and input to the peak level detector 220. Here, the peak level detector 220 is a circuit that detects the level of the peak of the first peak and the level of the peak of the second peak in the waveform of the wave intensity described above. When the peak level is detected in this manner, the determination level setting unit 224 sets the determination level K2 as a value that is lower than the detected peak level by a predetermined value.
[0058]
Information on the wave intensity WI read from the memory 222 is input to the calculation period setting unit 226, and the calculation period is set as a period in which the value exceeds the determination level K2. Within the calculation period, a calculation period is set. Within the calculation period, a calculation permission signal is output from the calculation period setter 226 to the calculator 232.
[0059]
On the other hand, the memory 228 stores information on the time differential dP / dt of the local blood pressure, and the memory 230 stores information on the time differential dU / dt of the blood flow velocity. The calculator 232 calculates the pulse wave propagation velocity c at each time according to the above equation (8). In this case, the pulse wave velocity c is calculated only within the set calculation period.
[0060]
The information of the pulse wave velocity c calculated in this way is output to the display processing unit 52 shown in FIG. 1 and also to the average value calculator 234, and the average value calculator 234 within the calculation period. The average value c ′ of the pulse wave propagation velocity c at is calculated. The information is output to the display processing unit 52 shown in FIG.
[0061]
The circuit configuration examples shown in FIGS. 2 and 3 are examples, and other circuit configurations can be adopted in addition to this. Further, each of the above operations may be realized by software processing.
[0062]
According to the setting of the calculation period based on the wave intensity described above, there is an advantage that it is possible to determine a period in which the forward wave on the artery is dominant, and to accurately calculate the pulse wave propagation velocity within the period. . Therefore, as long as the period in which the forward wave is dominant can be specified, biological information other than the wave intensity can be used.
[0063]
FIG. 4 shows an example of a screen displayed on the display unit 56 shown in FIG. As shown in FIG. 4, a plurality of pieces of information are displayed in a waveform with their time axes coincident with each other. Specifically, a local blood pressure P waveform 301, a blood flow velocity U waveform 302, a pulse wave velocity c waveform 303, a wave intensity WI waveform 304, and an electrocardiographic signal waveform 305 are displayed. Accordingly, for each of the first peak and the second peak of the wave intensity, the numerical value of the pulse wave velocity at each peak and the average value of the pulse wave velocity within each calculation period are, for example, m / s. Numerical values are displayed in units. In FIG. 4, reference numeral 305A indicates the first peak, and reference numeral 305B indicates the second peak.
[0064]
In FIG. 4, with respect to the wave intensity 304, as described above, the predetermined determination level K (= K1 or K2) is set, and the periods 310 and 312 in which the value of the wave intensity exceeds the determination level K are calculated. Set as period. That is, the pulse wave velocity c is calculated only in the calculation periods 310 and 312. As described above, for example, the periods 314 and 316 in which only the forward wave is generated may be estimated based on the R wave of the electrocardiogram, and the pulse wave velocity may be calculated in the periods 314 and 316. The display example shown in FIG. 4 is, of course, an example, and other display examples can be adopted.
[0065]
【The invention's effect】
As described above, according to the present invention, it is possible to accurately acquire data on properties of a local site in a blood vessel in real time.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present embodiment.
FIG. 2 is a diagram illustrating a circuit configuration example of a pulse wave propagation velocity calculation unit.
FIG. 3 is a diagram illustrating another circuit configuration example of a pulse wave propagation velocity calculation unit.
FIG. 4 is a diagram showing various waveforms displayed on the display screen.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Probe, 46 Ultrasonic image formation part, 48 Displacement calculating part, 50 Blood flow velocity calculating part, 52 Display processing part, 56 Display part, 200 Blood pressure monitor, 204 Local blood pressure calculating part, 206 Differentiator, 208 Differentiator, 210 Wave intensity (WI) calculation unit, 212 Pulse wave velocity calculation unit.

Claims (15)

Blood flow velocity calculating means for calculating a blood flow velocity for a specific part in the blood vessel;
Blood pressure calculating means for calculating blood pressure for the specific part;
First differential calculation means for calculating a time derivative of the blood flow velocity;
Second differential calculation means for calculating a time derivative of the blood pressure;
A pulse wave velocity calculating means for calculating a pulse wave velocity for the specific part from a ratio between the time derivative of the blood flow velocity and the time derivative of the blood pressure ;
A pulse wave velocity measuring device comprising: The apparatus of claim 1.
Including period determination means for determining a calculation period based on a heartbeat cycle;
The pulse wave velocity measuring device, wherein the pulse wave velocity is calculated within the calculation period. The apparatus of claim 2.
The pulse wave velocity measuring device, wherein the period determining means determines the calculation period based on predetermined biological information whose value varies according to a heartbeat period. The apparatus of claim 3.
The pulse wave velocity measuring device according to claim 1, wherein the predetermined biological information is a wave intensity that is an index for evaluating a circulatory dynamics of a circulatory system. The apparatus of claim 3.
The pulse wave velocity measuring apparatus according to claim 1, wherein the predetermined biological information is a second wave intensity that is an index for evaluating the circulatory dynamics of the circulatory system. The apparatus of claim 4.
The pulse wave propagation velocity measuring apparatus, wherein the period determination means sets the calculation period as a period in which the value of the wave intensity exceeds a predetermined determination level set in advance. The apparatus of claim 4.
The period determining means includes
A peak level detector for detecting a peak level of the wave intensity;
A determination level setting unit that sets a determination level as a value that is a predetermined value lower than the peak level;
A setting unit that sets the calculation period as a period in which the value of the wave intensity exceeds the determination level;
A pulse wave velocity measuring device comprising: The apparatus of claim 7.
2. The pulse wave velocity measuring device according to claim 1, wherein the peak level detection unit detects a first peak level and a second peak level of the wave intensity. The apparatus of claim 8.
The pulse wave velocity calculating means calculates an average value of the pulse wave velocity within the calculation period. A transducer for transmitting and receiving ultrasonic waves to a specific part of a blood vessel and outputting a received signal;
Blood flow velocity calculating means for calculating a blood flow velocity at the specific part based on the received signal;
Displacement calculating means for calculating the displacement of the blood vessel wall at the specific site;
Blood pressure calculating means for calculating blood pressure for the specific site using the displacement of the blood vessel wall;
Differential calculating means for calculating the time derivative of the blood flow velocity and the time derivative of the blood pressure;
Based on a ratio between the time derivative of the blood flow velocity and the time derivative of the blood pressure;
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 10.
The ultrasonic diagnostic apparatus, wherein the index value is a pulse wave velocity (pulse wave propagation velocity) propagating through the blood vessel wall. The apparatus of claim 11.
The ultrasonic diagnostic apparatus, wherein the blood pressure calculation means calculates the blood pressure for the specific part from the displacement of the blood vessel wall using the maximum blood pressure and the minimum blood pressure measured by a sphygmomanometer as reference values . The apparatus of claim 12.
A peak level detector for detecting the peak level of wave intensity, which is an index for evaluating the circulatory dynamics of the circulatory system,
A determination level setting unit that sets a determination level as a value that is a predetermined value lower than the peak level;
A setting unit that sets a calculation period as a period in which the value of the wave intensity exceeds the determination level;
Including
The ultrasonic diagnostic apparatus , wherein the pulse wave velocity is calculated within the calculation period . The apparatus of claim 13.
The ultrasonic diagnostic apparatus, wherein the peak level detection unit detects a first peak level and a second peak level of the wave intensity. The apparatus of claim 14.
An ultrasonic diagnostic apparatus comprising: a display for simultaneously displaying one or a plurality of information used for calculating the pulse wave propagation velocity together with the pulse wave velocity.

Images