JPS62176437A - State quantity measuring apparatus in blood circulatory system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention non-invasively measures arteriosclerosis, heart rate, blood flow, etc.
The present invention relates to a state quantity measuring device in the blood circulatory system.

<Prior Art> Conventionally, as shown in FIG. 5, as a non-invasive method of measuring the degree of arteriosclerosis, an oscillation output signal from an oscillator (21) is passed through a filter (22), an amplifier (23), and a matching circuit (24) to the transmitter (25) to transmit the ultrasonic wave of frequency f to the artery wall, and the reflected wave (frequency f + Δr) from the artery wall is sent to the receiver (26). The output signal from the receiver (26) is supplied to the mixer (30) via the matching circuit (27), the bandpass filter (28), and the amplifier (29), and the output signal from the receiver (26) is supplied to the mixer (30). ) is mixed with an oscillation output signal supplied via an attenuator (31), the mixed signal is supplied to an extraction circuit (32) to extract only the Doppler shift component, and a predetermined calculation is performed by an arithmetic circuit (33). A system has been proposed in which the calculation results are supplied to a display device (34) and the degree of arteriosclerosis is displayed (
(See Japanese Patent Application Laid-Open No. 176634/1983).

In the arteriosclerosis layer side device having the above configuration, in order to match the levels of the output signal from the receiver (26) and the oscillation output signal from the optical oscillator (21),
9) and an attenuator (31), and the amplification factor and attenuation factor are set to relatively small predetermined values.

<Problems to be solved by the invention> In the arteriosclerosis degree measuring device having the above configuration, the transmitter (
The ultrasonic output intensity from the receiver (25) is held constant, but the ultrasonic intensity at the receiver (26) varies depending on the angle of attachment to the artery wall, the distance to the artery wall, etc. , the amplitude of the mixed output signal from the mixer (30) varies.

This amplitude fluctuation does not pose a particular problem as long as the processing after the mixer (30) is performed analogously, but when processing is performed digitally, the following problems occur.

In other words, since the amplitude of the output signal from the receiver (26) fluctuates, a signal with a frequency f+Δf may have a different frequency f.
This is equivalent to applying amplitude modulation to the - signal. Therefore, even if an attempt is made to mix the oscillation output signal of frequency f from the oscillator (21) with the mixer (30) and extract only the Doppler shift component (frequency 1Δft>) with the extraction circuit (32), the Doppler shift component (frequency 1
Not only Δfl) but also the signal corresponding to the amplitude modulation signal (frequency 1Δf1±f-) is extracted, and after AID conversion, the combined signal of both will be understood as a Doppler shift component. The resulting signal includes errors caused by the angle of attachment to the artery wall, the distance to the artery wall, and the like. Therefore, there is a problem that the degree of arteriosclerosis finally obtained is inaccurate.

<Object of the invention> This invention was made in view of the above problems,
The purpose of the present invention is to provide a state quantity measuring device in a blood circulatory system that can accurately measure arteriosclerosis degree, heart rate, RKI flow, etc. by removing the influence of the installation angle to the artery wall, the distance to the artery wall, etc. It is said that

<Means for Solving the Problems> In order to achieve the above object, the state quantity measuring device in the blood circulatory system of the present invention uses an oscillation output signal from an oscillator as input and transmits ultrasonic waves to the arterial wall. A wave transmitter that transmits waves, a wave receiver that receives the reflected wave from the artery wall, and a conversion that amplifies the output signal from the wave receiver with a large amplification factor and chops it to convert it into a rectangular wave signal. a mixing detector that mixes the circuit, the oscillation output signal from the oscillator, and the square wave No. 18 to extract only the draft component;
The present invention is characterized by comprising a processing device that converts Doppler shift components into digital data and performs processing.

Effects> The state quantity measuring device in the blood circulatory system configured as described above transmits ultrasonic waves to the arterial wall by supplying the oscillation output signal of the oscillator to the wave transmitter. This ultrasound is reflected by the arterial wall, received by a receiver, and outputs a signal at a Doppler-shifted frequency. This signal is amplified by a large amplification factor by a conversion circuit, and
It is chopped and converted into a square wave signal,
By supplying this rectangular wave signal and the oscillation output signal to a mixed detector, 1. By extracting only the Doppler shift component and then using a processing device to convert the Doppler shift component into digital data and processing it, state quantities such as arteriosclerosis degree, heart rate, blood flow, etc. can be obtained.

<Example> DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings without referring to embodiments.

FIG. 3 is a schematic diagram showing the installation state of the state quantity measuring device in the blood circulatory system according to the present invention. wall(
The reflected wave of frequency f+Δf, which has been subjected to the Doorara effect due to the radial movement (pulsation) of 2), is received by the receiver (3).

FIG. 4 is a diagram showing a waveform diagram of an ultrasonic signal transmitted from a wave transmitter (1) and a waveform diagram of a reflected wave signal from an artery wall (2), in the radial direction of the artery wall (3). Δ[ fluctuates between positive and negative in response to the expansion and contraction of (see a and b in Figure B)
.

FIG. 1 is a block diagram showing a practical example of a state quantity detection device for a blood circulatory system, in which an oscillator (4
) is supplied to the transmitter (1).

And a matching circuit (8), a bandpass filter (9),
The output signal from the wave receiver (3) is supplied to the mixed detector (11) via the waveform shaping circuit (G) and the waveform shaping circuit (G)), and the oscillation output signal from the oscillator (4) is also supplied to the mixed detector (11). (11). Furthermore, this mixed detector (
The output signal from the frequency analyzer (11) is supplied to the frequency analyzer (13) via the A/D converter (12), and the analysis output signal from the frequency analyzer (13) is supplied to the display device (14). There is. However, the frequency analysis device (13) may have a dedicated circuit configuration or may be a microcomputer having a dedicated program.

The oscillator (4) outputs an oscillation output signal of about 10 MHz, the amplifier (6) has a predetermined amplification factor that is not very large, and the waveform shaping circuit has a very large A rectangular wave is generated by amplifying the signal with an amplification factor and chopping the amplified signal at a predetermined level, thereby eliminating the fluctuation of the signal manually input to the mixed detector (11). However, a mixed detector (
The amplitude of both (No. 8) input to the oscillator (4) is set so that the oscillation output signal from the oscillator (4) is significantly larger than the rectangular wave.

The mixed waveform in the above case will be explained as follows.

The amplitudes of the oscillation output signal from the oscillator (4) and the reflected wave having a Doppler shift component are A and B (A>>
8>, the oscillation output signal from the oscillator (4) is A 5in (2yrft), and the reflected wave is B 5in.
It can be expressed as (2yr (f+Δ′)t).

Therefore, the mixed waveform is A 5in(2π f t) +3 5in(2
yr (f +Δf) t)=A [1+ (2B
/A) cos(2πΔft)+(8/A>E
s+n(2πft+ψ〉#AM+(2[3/A)co
s(2πΔr t )11/2Sin(27rft+ψ
) 嬌A [1+(B/A)cos(2πΔf't)]5i
n(2πft+ψ) = [A+B cos(2πΔft)]5in(2yr
ft+ψ) However, the modification of the above equation is valid because (B/A)2#O and 1>>23/A.

Therefore, by detecting the above mixed waveform, 8c
os(2πΔrt>, that is, only the Doppler shift component is detected.

Above, we have explained the case where both signals are sine waves, but the above rectangular wave is a basic sine wave (frequency is f + Δ
), with harmonics of 2 times, 3 times, etc. Since the Doppler shift component is 100 Hz), it is possible to similarly extract only the Doppler shift component by applying the above deduction.

Further, the frequency analyzer (13) digitally performs frequency analysis, and specifically, for example, v = (c/2 cos θ) (Δf/f) (C is the in-vivo sound velocity, approximately 1500n /sec) based on the arterial wall (
The motion speed of 2) is used equally. Furthermore, the above matching circuit (7
1 [81 is for impedance matching between the circuit, the transmitter (1), and the receiver (3).

The operation of the state quantity measuring device in the blood circulatory system having the above configuration will be explained with reference to FIGS. 1 and 2 showing waveform diagrams.

The oscillation output signal of frequency f (see Fig. 2A) from the oscillator (4) is transmitted to the bandpass filter (5) and the amplifier (6).
, and a matching circuit (7) to the transmitter (1), an ultrasonic wave with a frequency f is transmitted from the transmitter (11) toward the artery wall (2). is the artery wall (′
Since it is reflected in a Doppler-shifted state corresponding to the radial expansion and contraction of 2J, a signal (frequency f + Δf) containing a Doppler shift component is output from the receiver (3), and the matching circuit (8) , and the waveform shaping circuit (K)] via the bandpass filter (9). Here, due to the radial expansion and contraction of the artery wall (2), the receiver (3)
Since the angle corresponding to the artery wall (2) and the distance to the artery wall (2) change, the reception intensity of the ultrasound signal at the receiver (3) changes, and the signal of a predetermined frequency changes. The state is similar to that of amplitude modulation (see Figure 2B)
.

This signal with amplitude fluctuations is greatly amplified by the waveform shaping circuit (g) and chopped at a predetermined level, so that not only the initially large amplitude part but also the small amplitude part is shaped into a rectangular wave. (See C in Figure 2)
. In other words, the signal (frequency f + Δf
), and the oscillation output signal @(frequency f
) is supplied to the mixed detector (11), only the Doppler shift component Δf is extracted (see FIG. 2), and converted into digital data by the A/D converter (12). This digital data is supplied to a frequency analyzer (13) to undergo digital analysis processing, and the results of this analysis processing are supplied to a display device (14) to determine the degree of arteriosclerosis, heart rate, and blood flow. It is possible to display state quantities in the blood circulatory system.

<Effects of the Invention> As described above, the present invention eliminates measurement errors caused by changes in the intensity of ultrasonic signals received by a wave receiver, and accurately calculates the state quantity C in the blood circulatory system. It has the unique effect of being able to measure accurately.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the state quantity measuring device in the blood circulatory system according to the present invention, Fig. 2 is a signal waveform diagram of each part, and Fig. 3 is a diagram of the wave transmitter and receiver for the arterial wall. FIG. 4 is a signal waveform diagram illustrating Doplass shift, and FIG. 5 is a block diagram showing a conventional example.

Claims (1)

[Claims] 1. Input the oscillation output signal from the oscillator. Ultrasonic waves are transmitted to the arterial wall using receives reflected waves from the arterial wall. Increase the receiver and the output signal from the receiver. Amplify with a high amplification rate, and also Conversion time to convert to square wave signal an oscillation output signal from the oscillator; and Doppler by mixing the above square wave signals. a mixed detector that extracts only the shift component; Convert Doppler shift components into digital data Equipped with a processing device that converts and processes In the blood circulatory system, which is characterized by state quantity measuring device.