JP5170751B2 - Blood pump device - Google Patents

Description

  The present invention relates to a blood pump device used for extracorporeal circulation and an artificial heart, and more particularly to a blood pump device with a thrombus detection function capable of measuring the amount of thrombus present in blood.

  An artificial heart as a device that performs the function of the heart mainly includes a blood pump that circulates blood and a control device that controls its operation. Here, the blood pump device including the blood pump and its control device is referred to as a blood pump device. If a blood pump for an artificial heart breaks down or if the device itself operates abnormally frequently, it may impair human life, so take extra care to prevent this from happening. is important.

  In particular, when a thrombus (blood clot. A relatively small thrombus has a size of about 10 to 50 μm) occurs in blood, this may cause myocardial infarction or cerebral infarction. For example, when the blood vessel wall becomes unsmooth due to aging or the like, the blood vessel itself hardens and the blood vessel wall comes off. This enters the blood and becomes a thrombus that circulates in the body with the blood. Of course, even in a normal person, a small thrombus has occurred, but such a thrombus disappears in the process of circulating in the body and has no particular adverse effect on the human body.

  However, for heart disease patients, the effect of blood clots present in the blood is greater than that for normal persons. In particular, in blood pumps used for extracorporeal circulation or artificial hearts, blood clots can occur in the blood pump and in the parts of the conduit (connection pipe) connected to the inlet and outlet of the blood pump. Of course, as described above, there is a case where a portion other than the blood pump or the condition, that is, a thrombus generated in the actual blood vessel is trapped (residual) in the blood pump or the condition in the process of passing the blood pump and the condition. I can think of it.

Thrombus causes clogging of peripheral thin blood vessels, so when such a thrombus occurs, it is important to remove it quickly by taking a thrombolytic agent.
This is because when a thrombus occludes a blood vessel, the occluded blood vessel site malfunctions. In particular, cerebral blood vessels cause cerebral infarction, and the heart leads to myocardial infarction, which causes great damage to the patient. In addition, if thrombus remains in the blood pump, it may cause malfunction of the pump.

In response to such a current situation, a thrombus measurement device that measures a thrombus formed in a blood vessel with a laser beam or a light emitting diode beam has been proposed (see Patent Document 1).
The technique described in Patent Document 1 irradiates a blood layer with laser light or light-emitting diode light as pulsed light, measures the amount of reflected light or transmitted light with respect to each pulse of the pulsed light, and measures blood from the measurement data. It measures blood clots inside.

  In addition, as another thrombus measurement method, a technique for irradiating an ultrasonic wave from the body surface and detecting a thrombus in, for example, a cerebral blood vessel using the ultrasonic Doppler displacement has been proposed (see Patent Document 2). ). The technique described in Patent Document 2 is an ultrasonic diagnostic apparatus having a thrombus imaging function, and has a mode for imaging an instantaneous peak correlated with a thrombus in a cerebral blood vessel.

  That is, first, an ultrasonic beam is generated from a probe in contact with the surface of a living body (or inside a body cavity), and this is electronically scanned. And the reflected wave reflected from the thrombus etc. in the body is detected. This detection is performed by forming a tomographic image and a two-dimensional Doppler image based on the received signal. In other words, during the synthesis of the tomographic image and the Doppler image, coloring or highlight display is performed so that the instantaneous peak is conspicuous.

In this way, by displaying so that the instantaneous peak is clear in the composite image, it is possible to grasp the occurrence location of the instantaneous peak and the behavior from this display image.
On the other hand, the power spectrum can be displayed based on the echo signal of the blood flow that flows through the blood vessels in the brain. Here, the power spectrum is a graph with the horizontal axis representing the time axis and the vertical axis representing the velocity axis, and the luminance corresponding to the power of the Doppler component is detected from the power spectrum. Here, the power of the Doppler component is related to the blood flow velocity. The blood flow is measured from the blood flow rate to the last, and the power spectrum is obtained based on it. The reason why the vertical axis representing luminance is the velocity axis is because the moving speed of the thrombus is taken into consideration. That is, not all instantaneous peaks are imaged, but only instantaneous peaks that satisfy a predetermined speed condition are specified in consideration of the moving speed of the thrombus.

  The portion of high brightness observed in such a power spectrum is generally called HITS (High Intensity Transient Signal). Clinically, it is said that people with more frequent HITS are more likely to have cerebral infarction. There is a correlation between HITS and cerebral infarction.

  In order to obtain a Doppler-displaced signal from an ultrasonic echo signal, it is necessary to perform a predetermined process on the received signal, unlike a simple ultrasonic image diagnostic apparatus. In the technique described in Patent Document 2, first, a received signal is input to an orthogonal transformer. In this orthogonal transformer, reference signals having a phase difference of 90 degrees with respect to the received signal are mixed, and the received signal is converted into a complex signal.

  This complex signal is supplied to a filter called a wall motion filter, where a huge echo signal from a low-speed moving body such as a heart wall is removed. That is, the wall motion filter is a high-pass filter that removes a large reflected wave from a low-speed moving body. The complex signal from which the large reflected wave is removed is sent to the autocorrelator, and a well-known autocorrelation operation is performed on the complex signal. Here, considering the resolution of the flow velocity, an appropriate frequency of the ultrasonic wave emitted from the ultrasonic probe is about 5 to 10 MHz.

JP 2002-345787 A JP 2001-137242 A

  However, the thrombus measurement device using laser light or light-emitting diode light as described in Patent Document 1 has a large size and cannot be carried by being attached to a blood pump. This is because, firstly, a laser device that generates laser light is required. In Patent Document 1, it is described that light-emitting diode light may be used. However, in order to apply a light beam having a certain wavelength, it is basically considered that laser light is optimal.

  Secondly, since the transmittance of the irradiated laser beam differs depending on the blood saturation concentration, there is a problem that it is impossible to distinguish from the data whether the difference in transmitted light is due to a difference in saturation concentration or a thrombus. . In order to solve these problems, 1) detection processing means based on signal waveform pattern recognition and 2) detection processing means accompanying signal processing are required, and a high-performance data processing unit (digital signal processing) for this purpose is required. Needed.

Also, as in the technique described in Patent Document 2, when detecting a thrombus in a blood vessel from the body surface using the ultrasonic Doppler effect, a device for detecting a weak ultrasonic echo Doppler signal is large. Therefore, it is difficult to carry it with an implantable blood pump. This is because the above-described wall motion filter and autocorrelator are realized by digital signal processing, and the circuit scale for capturing weak Doppler displacement becomes large.
The ultrasonic frequency used in this ultrasonic diagnostic apparatus is considered to be 5 to 10 MHz, and the wavelength is 150 to 300 μm when the velocity of ultrasonic waves in blood and body tissue is 1500 m / sec. With this, a thrombus of 50 μm or less existing in blood cannot be detected.

The present invention has been made to solve the above-described problems, and detects a thrombus without using a laser device or a large-scale device such as an ultrasonic diagnostic device for detecting a Doppler component. An object of the present invention is to provide a blood pump device with a thrombus detection function.
The blood pump device of the present invention is effectively used for extracorporeal circulation or an implantable artificial heart.

  In order to solve the above problems and achieve the object of the present invention, the present invention is a blood pump device in which a blood pump and a controller are cable-connected, and the blood pump has a blood inflow port and a blood outflow port. . The first connection pipe is connected to the blood inflow port, and the second connection pipe is connected to the blood outflow port. First and second ultrasonic transducers are attached to the outer peripheral portions of the first and second connection pipes, respectively. The first ultrasonic transducer transmits an ultrasonic wave to the blood passing through the first connecting tube, receives the reflected wave, and converts it into an electrical signal. The second ultrasonic transducer transmits an ultrasonic wave to the blood passing through the second connecting pipe, receives the reflected wave, and converts it into an electrical signal.

  In addition, the controller receives each electrical signal obtained by the first and second ultrasonic transducers, and converts the electrical signal into a first RF signal and a second RF signal, respectively. A first signal processing unit that detects the first RF signal and the second RF signal and logarithmically compresses to obtain a first detection / logarithm compression signal and a second detection / logarithm compression signal; The signal processing unit of the first and the output values of the first detection / logarithm compression signal and the second detection / logarithm compression signal are compared with a predetermined threshold value, and the number of output values exceeding the threshold value is counted as the thrombus number. 1 thrombus counting section and second thrombus counting section, and a judgment section for comparing the thrombus counts counted by the first and second thrombus counting sections.

  According to the present invention, since ultrasonic transducers having a high frequency of 30 to 50 MHz are installed in the first connection pipe and the second connection pipe, the detection output of the reflected wave from the thrombus without using Doppler displacement. Can be obtained. That is, in the present invention, the detection of the thrombus, which is an ultrasonic scatterer, is performed by the first connection pipe and the second connection pipe of the blood pump. Then, it is detected how many scatterers (thrombus) having a reflection intensity of a predetermined level or more have passed per unit time.

The following can be seen from the number of thrombus that passed through the measurement site.
A) If the number of counts is the same at the inlet and outlet of the blood pump, it can be seen that no blood clots have occurred in the blood pump due to blood pump failure or aging.
B) If the number of outlets is larger than that of the blood pump inlet, it is assumed that a thrombus caused by the blood pump has occurred.
C) If the number of counts at the outlet is small compared to the inlet of the blood pump, it is assumed that a thrombus has occurred due to a cause other than the blood pump, and that the thrombus remains in the blood pump. Is done.

  In any case, by counting the number of blood clots at the inlet and outlet of the blood pump, if the count value becomes abnormal (greater than or equal to the threshold value), a warning prompting the administration of a thrombolytic agent or vasodilator Can be issued. If too much thrombolytic agent is taken, there is a problem that even a slight injury makes it difficult for blood to coagulate. If too much vasodilator is taken, there is a problem that anemia occurs. Therefore, it is necessary to pay close attention to the use of these drugs. For this reason as well, it is necessary to accurately grasp the state of blood clots, particularly in patients with heart disease.

Here, the reason why the ultrasonic wave having a relatively high frequency of 30 to 50 MHz is used is to increase the spatial resolution by shortening the wavelength. That is, since the ultrasonic wave has a wavelength of 30 to 50 μm, a relatively small thrombus can be detected.
In addition, by installing the ultrasonic transducers at the blood inflow port and the blood outflow port instead of the body surface, the distance between the thrombus in the blood and the transducer can be reduced and the attenuation of the ultrasonic wave can be reduced. As a result, there is no need to use Doppler displacement, and the echo from the thrombus can be directly detected with a high S / N ratio. Therefore, there is an advantage that only the signal processing of detection and logarithmic compression is sufficient for the subsequent processing. Therefore, unlike the one described in Patent Document 2, a quadrature detector, a wall motion filter, and an autocorrelator are not required, and the thrombus detection unit can be made portable enough to include the transmission / reception unit. .

  According to the present invention, it is possible to provide a blood pump device having a thrombus detection function that can be applied to either extracorporeal circulation or an artificial heart without requiring a large-scale device or a signal processing circuit.

The configuration and operation of the embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows the overall configuration of an implantable left ventricular assist device blood pump device showing a first embodiment of the blood pump device of the present invention. An artificial heart blood pump apparatus 1 shown in FIG. 1 includes a blood pump 2, first and second connecting pipes 3, 4, a portable controller 5, a cable 6, and first and second superlattices described later. Sound wave transducers 7 and 8 are provided.

  The blood pump 2 and the connecting pipes 3 and 4 are embedded in the body. The blood pump 2 has a blood inflow port (inlet) through which blood flows and a blood outflow port (outlet) through which blood flows out. The blood inflow port of the blood pump 2 is connected to the left ventricle of the heart by a first connection tube 3, and the blood outflow port is connected to the aorta by a second connection tube 4. By connecting in this way, blood discharged from the left ventricle flows into the blood pump 2 and flows out into the aorta with the help of the blood pump 2. In other words, it can be said that the blood pump 2 and the connecting pipes 3 and 4 have a blood bypass between the left ventricle and the aorta to secure the blood flow of the patient whose heart function is reduced.

  The controller 5 is carried outside the body, for example, by a belt (not shown). The controller 5 is connected with batteries 11 and 12 as power supply sources. The cable 6 electrically connects the blood pump 2 and the controller 5. Therefore, a part of the cable 6 is inserted into the body.

FIG. 2 is an explanatory diagram for explaining the configuration of the controller 5 and the first and second ultrasonic transducers 7 and 8.
As described above, the first and second connection pipes 3 and 4 are connected to the blood inflow port and the blood outflow port of the blood pump 2, respectively. Blood discharged from the left ventricle flows into the blood pump 2 via the connecting tube 3. The blood flowing out from the blood pump 2 is sent to the aorta via the connecting pipe 4.

  A first ultrasonic transducer 7 is attached to the outer periphery of the connection tube 3, and a second ultrasonic transducer 8 is attached to the connection tube 4. These two ultrasonic transducers 7 and 8 are disposed in the vicinity of the blood inflow port and the blood outflow port, respectively, and are electrically connected to the controller 5 via the cable 6 shown in FIG.

Here, the ultrasonic transducers 7 and 8 will be described. In simple terms, the ultrasonic transducer is a converter (sensor) that performs conversion from an electric signal to an ultrasonic wave and vice versa, that is, conversion from an ultrasonic wave to an electric signal. The ultrasonic transducer used here has the same structure as that of a normal ultrasonic transducer, and is composed of a piezoelectric material, a backing material, an acoustic matching layer, and an acoustic lens.
Usually, what is called an ultrasonic probe or ultrasonic transducer applies ultrasonic waves to an object, measures the flow velocity from the Doppler effect of the reflected wave, and measures the position and amount of the thrombus via the flow velocity.

  This embodiment is characterized in that the position and amount of the thrombus can be measured regardless of the flow rate. That is, in this embodiment, Doppler displacement is not used as in a normal ultrasonic diagnostic apparatus. In this embodiment, since the ultrasonic transducers 7 and 8 are respectively attached to the connection pipes 3 and 4 of the blood pump 2, the distance between the thrombus in the blood to be measured and the ultrasonic transducer is very close. For this reason, even if the frequency of the ultrasonic wave is made higher than usual, the attenuation of the ultrasonic wave can be reduced, and the ultrasonic wave can be irradiated to the thrombus.

  In the present embodiment, the frequency of ultrasonic waves transmitted from the ultrasonic transducers 7 and 8 is set to 30 to 50 MHz, which is 3 to 10 times higher than the normal frequency of 5 to 10 MHz. Thereby, the wavelength of an ultrasonic wave becomes 30-50 micrometers (the sound speed of the ultrasonic wave in blood and a body tissue is 1500 m / sec), and a comparatively small thrombus can be found. Moreover, in this Embodiment, the radius of the connection pipes 3 and 4 is set to about 5 mm. Therefore, the attenuation of the ultrasonic wave can be reduced as compared with transmission and reception from the body surface performed by a normal ultrasonic diagnostic apparatus, and the echo of the thrombus can be easily detected.

  The controller 5 is provided with a processor 21, a motor drive circuit 22 that rotates the impeller of the blood pump 2, and a magnetic levitation control circuit 23 that magnetically levitates the impeller in the blood pump 2. A memory device 24 is connected to the processor 21, and various data and the like are exchanged with the memory device 24. In the memory device 24, for example, the monitoring result of the operating state of the blood pump 2 and the operating conditions of the blood pump 2 are stored.

  Further, the controller 5 receives and processes the first and second transmission / reception units 25a and 25b connected to the first and second ultrasonic transducers 7 and 8 and signals from the transmission / reception units 25a and 25b. 1st and 2nd thrombus which receives the signal from 1st and 2nd signal processing part 26a, 26b and signal processing part 26a, 26b, and counts the thrombus in the blood detected with the ultrasonic transducers 7 and 8 Counting units 27a and 27b are provided. Outputs from the thrombus counting units 27a and 27b are supplied to the determination unit 28, where a predetermined determination is made. And the determination result by the determination part 28 is displayed on the display part 29 which shows a specific example of an alerting | reporting part.

  Examples of the display unit 29 include a liquid crystal display and an organic EL (Electro Luminescence) display. However, a lamp such as an LED (Light Emitting Diode) may be turned on and off.

Next, based on FIG. 2, FIG. 3, operation | movement of the embodiment of this invention is demonstrated.
FIG. 3A is an explanatory diagram showing the arrangement of the ultrasonic transducers 7 and 8. Here, a case where a single ultrasonic transducer is used for both transmission and reception is shown.
As described above, as the ultrasonic transducers 7 and 8, the piezoelectric vibrator 31 sandwiched between the backing material 32 and the acoustic matching layer 33 is used. An acoustic lens may be interposed between the acoustic matching layer 33 and the connecting pipes 3 and 4.

  Each of the transmission / reception units 25 a and 25 b (see FIG. 2) transmits a drive signal to the ultrasonic transducers 7 and 8 based on a transmission timing signal supplied from the processor 21 of the controller 5. The ultrasonic transducers 7 and 8 transmit ultrasonic waves to the blood flowing in the connection tubes 3 and 4 when the drive signals are supplied from the transmission / reception units 25a and 25b.

  When ultrasonic waves are transmitted by the ultrasonic transducers 7 and 8b, reflected waves (echoes) of ultrasonic waves are emitted from the walls of the connection tubes 3 and 4 and blood cells or thrombus in the blood, respectively. Each of the ultrasonic transducers 7 and 8 receives an ultrasonic reflected wave (echo), converts it into an electrical signal, and transmits it to the first and second transmission / reception units 25a and 25b. The first and second transmission / reception units 25a and 25b convert the electrical signals supplied from the ultrasonic transducers 7 and 8 into first and second reception RF (Radio Frequency) signals.

FIG. 3B shows the first and second received RF signals respectively converted by the transmission / reception units 25a and 25b of FIG.
As shown in FIG. 3 (b), in the first and second received RF signals, transmission noise when ultrasonic waves are transmitted is detected, and then from the wall on the side where the ultrasonic transducers 7 and 8 are arranged. An echo 36a is detected. Subsequently, the echo 37 from the thrombus 34 existing together with the blood flow in the connection tubes 3 and 4 is detected, and finally the echo 36b reflected from the wall of the port farther from the ultrasonic transducers 7 and 8 is detected.

  Normally, if the amplitudes of the echoes 36a and 36b reflected from the walls of the connecting tubes 3 and 4 are “1”, the amplitude of the echo 37 reflected by the thrombus 34 is “0.1” or more. However, when the respective echoes 36a, 36b, and 37 are illustrated with this size, the echo 37 becomes very small. Therefore, in this example, the echo 37 is represented by an amplitude of about “0.5” with respect to the amplitude “1” of the echoes 36a and 36b, and the echo 37 is schematically made conspicuous.

  Each transmitting / receiving unit 25a, 25b transmits the converted first and second received RF signals to the first and second signal processing units 26a, 26b, respectively. Each of the signal processing units 26a and 26b performs detection and logarithmic compression on the supplied first and second received RF signals. FIG. 3C shows the first and second detection / logarithm compression signals detected and logarithmically compressed by the signal processing units 26a and 26b.

  Here, touching on why logarithmic compression is necessary, the received RF signal obtained from an ultrasonic echo usually has a large difference in height from a very small amplitude to a very large amplitude. For this reason, when the gain is increased in order to detect a small signal, there arises a problem that the large signal is out of range. Therefore, the enhancement degree is relatively increased for a signal having a small amplitude, and the enhancement degree is weakened for a signal having a large amplitude. This is the reason for logarithmic compression.

  The first and second detection / logarithmic compression signals shown in FIG. 3C detected and logarithmically compressed by the signal processing units 26a and 26b (see FIG. 2) are respectively the first and second thrombus counting units. 27a and 27b. In the thrombus counting units 27a and 27b, the number of thrombus is literally counted. The thrombus counted here is a thrombus exceeding a certain threshold. That is, in the detection / logarithmic compression signal shown in FIG. 3C, the output 38 corresponding to the echo 37 (see FIG. 3B) reflected by the blood cell or the thrombus 34 has a predetermined threshold value. Only when it exceeds, count as the number of blood clots.

  This is because the output 38 of the detection / logarithmic compression signal becomes a larger value as the size of the thrombus increases, but a thrombus whose value is below a certain threshold value is not a problem even in the bloodstream. . Also, counting the thrombus only when the output 38 exceeds a predetermined threshold is also for distinguishing the thrombus 34 from blood cells that are much smaller than the thrombus 34. For example, even in a normal person, there are quite a few small blood clots that do not affect life. It is necessary to precisely set the size of the thrombus over which the size is counted by the person who uses the apparatus. Then, depending on the content of the count, a treatment policy is determined as to whether to increase the dose of the thrombolytic agent or to take the vasodilator.

  For this reason, in the first and second thrombus counting units 27a and 27b, the thrombus passes through the installation place of the ultrasonic transducers 7 and 8 only when the threshold value determined in accordance with the person using the apparatus is exceeded. It is determined that it was done.

The judgment unit 28 shown in FIG. 2 compares the count results of the first thrombus counting unit 27a and the second thrombus counting unit 27b, and how the number of thrombus changes between the inlet and the outlet of the blood pump 2. Determine if you did.
For example, it is assumed that the first thrombus counting unit 27a counts “100” thrombus exceeding a threshold value within a predetermined measurement time T1. Then, after a predetermined deviation time TL has elapsed since the start of the predetermined measurement time T1, the second thrombus counting unit 27b exceeds the threshold value within the predetermined measurement time T2 having the same length as the predetermined measurement time T1. Assume that the thrombus has been counted “150”.
Here, the predetermined deviation time TL means that the blood flow passes through the position corresponding to the first ultrasonic transducer 6 and then passes through the blood pump 2 and the position corresponding to the second ultrasonic transducer 7. It takes time to complete.

  Thus, when the counting result of the thrombus counting unit 27a is larger than the counting result of the thrombus counting unit 27b, the number of thrombus passing through the blood inflow port of the blood pump 2 is greater than the number of thrombus passing through the blood outflow port. There will be many. Therefore, the determination unit 28 determines that there is some abnormality in the blood pump 2 and a thrombus has occurred.

On the other hand, it is assumed that the first thrombus counting unit 27a counts “150” thrombus exceeding the threshold value within a predetermined measurement time T1. Then, after a predetermined deviation time TL has elapsed from the start of the predetermined measurement time T1, it is assumed that the second thrombus counting unit 27b has counted “100” thrombus exceeding the threshold within the predetermined measurement time T2.
In this case, the number of thrombus passing through the blood inflow port of the blood pump 2 is smaller than the number of thrombus passing through the blood outflow port. Therefore, the determination unit 28 determines that a thrombus remains in the blood pump 2.
If the counting results of the first thrombus counting unit 27a and the second thrombus counting unit 27b are substantially the same, the determination unit 28 has no thrombus generation in the blood pump 2 and no thrombus remains. Judge.

The result determined by the determination unit 28 is displayed by the display unit 29. For example, when the determination unit 28 determines that a thrombus remains in the blood pump 2, a message “Thrombus remains in the blood pump. Please administer a thrombolytic agent” is displayed. Is done.
In place of the display on the display unit 29, a warning message can be generated by voice.

The determination unit 28 determines whether the count result of the thrombus count unit 27a or the count result of the thrombus count unit 27b exceeds a predetermined value. This predetermined value is determined according to the person who uses this apparatus, similarly to the threshold value related to the thrombus counting units 27a and 27b.
When the counting result of the first thrombus counting unit 27a or the second thrombus counting unit 27b exceeds a predetermined value, the determination unit 28 determines that administration of a thrombolytic agent or a vasodilator is necessary. .
On the other hand, when the counting result of the first thrombus counting unit 27a or the second thrombus counting unit 27b does not exceed a predetermined value, the determination unit 28 does not need to administer a thrombolytic agent or a vasodilator. Judge.

As described above, when the determination unit 28 determines that the administration of the thrombolytic agent or the vasodilator is necessary, a warning for prompting the administration of the thrombolytic agent or the vasodilator is issued. For example, the message is displayed on the message display unit 29 “It is necessary to administer a thrombolytic agent or a vasodilator”. Note that the warning prompting the administration of the thrombolytic agent or the vasodilator may be generated by voice.
As a result, it is possible to prevent clogging of peripheral thin blood vessels, to make the doses of the thrombolytic agent and vasodilator suitable, and to prevent both adverse effects of thrombus and side effects due to administration.

  In the present embodiment, the first and second connecting pipes 3 and 4 are circular pipes having a constant thickness, but the thickness of the portion of the connecting pipes 3 and 4 to which the ultrasonic transducers 7 and 8 are attached is You may make it thinner than other partial thickness. By forming in this way, attenuation of the ultrasonic wave transmitted from the ultrasonic transducers 7 and 8 can be further reduced, and the echo can be reliably detected even if the thrombus is small.

FIG. 4 is an explanatory view for explaining a second embodiment of the blood pump device of the present invention.
The blood pump device according to the second embodiment of the present invention has the same configuration as that of the first embodiment of the blood pump device described with reference to FIGS. A plurality of first and second ultrasonic transducers are provided.

  FIG. 4 shows eight ultrasonic transducers 41a to 41h, eight transmission / reception units 42a to 42h, and an adder 43 that combines the reception RF signals transmitted from these transmission / reception units 42a to 42h.

  The configuration of FIG. 2 corresponding to FIG. 4 is the first ultrasonic transducer 7 and the first transmitting / receiving unit 25a, or the second ultrasonic transducer 8 and the second transmitting / receiving unit 25b. That is, in the present embodiment, eight first and second ultrasonic transducers are provided, and one set of them is shown in FIG.

  As shown in FIGS. 2 and 3, in the artificial heart blood pump apparatus 1, one ultrasonic transducer 7 and 8 is attached to each of the first and second connection pipes 3 and 4. In such a configuration, there may be a case where the amplitude values of the first and second received RF signals obtained by the ultrasonic transducers 7 and 8 become small. Therefore, by providing a plurality of first and second ultrasonic transducers, the SN ratio of the first and second received RF signals is improved and the amplitude value is increased.

  As shown in FIG. 4, the eight ultrasonic transducers 41 a to 41 h are arranged at equal intervals in the circumferential direction of the connecting pipe 44 made of a cylinder. Therefore, the ultrasonic transducer 41 a and the ultrasonic transducer 41 e are opposed to each other with the axis of the connection pipe 44 interposed therebetween. Similarly, the ultrasonic transducer 41b and the ultrasonic transducer 41f, the ultrasonic transducer 41c and the ultrasonic transducer 41g, and the ultrasonic transducer 41d and the ultrasonic transducer 41h are opposed to each other across the axis of the connection tube 44.

  The eight ultrasonic transducers 41a to 41h are connected to the eight transmission / reception units 42a to 42h, respectively. The eight transmission / reception units 42a to 42h have transmission channels (transmission CH1 to 8) and reception channels (reception CH1 to 8), respectively. Each transmission channel is connected to a transducer 41a to 41h and a processor (see FIG. 2), and each reception channel is connected to a transducer 41a to 41h and an adder 43, respectively.

Next, based on FIG. 4, the operation when eight ultrasonic transducers 41 a to 41 h are provided will be described.
The transmission channels (transmission CH1-8) of the transmission / reception units 42a-42h are ultrasonic transducers based on transmission timing signals 1-8 (transmission CH1-8, respectively) supplied from a processor (not shown) of the controller 5. A drive signal is transmitted to 41a-42h.

  When drive signals are supplied from the transmission channels (transmission channels 1 to 8) of the transmission / reception units 42a to 42h to the ultrasonic transducers 41a to 41h, the ultrasonic transducers 41a to 41h perform ultrasonic waves on the blood flowing in the connection tube 44. Send. And as demonstrated in FIG. 3, in each ultrasonic transducer 41a-41h, an ultrasonic echo is detected and this is converted into an electrical signal (reception RF signal). The reception RF signals obtained by the ultrasonic transducers 41a to 41h are transmitted to the adder 43 via the reception channels (reception CH1 to 8) of the transmission / reception units 42a to 42h. The adder 43 synthesizes the received RF signals supplied from the reception channels (reception CH1 to 8) of the transmission / reception units 42a to 42h.

  Here, the ultrasonic transducer 41a and the ultrasonic transducer 41e have opposite directions of transmitting ultrasonic waves. Therefore, it is conceivable that the ultrasonic echo generated by the ultrasonic wave transmitted by itself receives interference from the ultrasonic wave transmitted from the ultrasonic transducer arranged on the opposite side. This can be solved by delaying the transmission of the ultrasonic wave by the ultrasonic transducer 41e so that the ultrasonic wave from the ultrasonic transducer 41e is not received within the reception period of the ultrasonic transducer 41a.

Hereinafter, specific numbers will be shown and described. In order to simplify the calculation, the inner wall of the connection tube where the ultrasonic transducer is disposed is used as a transmission / reception surface.
The speed of sound in blood is 1500 m / sec. Generally, since the radius of the connecting pipe is set to about 5 mm, here, the radius of the connecting pipe 44 is set to 4.5 mm so as to simplify the calculation.

In the second embodiment shown in FIG. 4, the transmission / reception range (detection range) of the ultrasonic transducer 41 a may be 4.5 mm from the installed wall surface to the center of the connection pipe 44. This is because the range from the center to the facing side is handled by the ultrasonic transducer 41e. Therefore, the reception period of the ultrasonic transducer 41a is
4.5 × 10 ⁻³ × 2/1500
= 6 × 10 ⁻⁶ [sec]
= 6 [μs]
It becomes.

Actually, the reception period is set to 6.125 [μs] in order to obtain data slightly from the center to the facing side so as not to miss the ultrasonic echo. Therefore, the transmission / reception range (detection range) is
1500 × 6.125 × 10 ⁻⁶ / 2
= 4.59375 × 10 ⁻³ [m]
= 4.59375 [mm]
It becomes.

In order to prevent the ultrasonic wave from the ultrasonic transducer 41e from entering the transmission / reception range during the reception period of 6.125 [μs], the transmission of the ultrasonic transducer 41e may be delayed. The time for delaying the transmission of the ultrasonic transducer 41e is:
6.125 × 10 ⁻⁶ − (4.5 × 10 ⁻³ × 2-4.59375 × 10 ⁻³ ) / 1500
= 6.125 × 10 ⁻⁶ -2.9375 × 10 ⁻⁶
= 3.1875 × 10 ⁻⁶ [sec]
= 3.1875 [μs]
It becomes. That is, transmission of the ultrasonic transducer 41e may be delayed by 3.1875 [μs] or more.

Here, it will be delayed by 3.2 [μs] with a margin. In that case, the time elapsed since the ultrasonic transducer 41e transmitted ultrasonic waves at the time when 6.125 [μs], which is the reception period, has elapsed since the ultrasonic transducer 40a transmitted ultrasonic waves,
6.125-3.2
= 2.925 [μs]
It becomes.
Thereby, the ultrasonic wave transmitted from the ultrasonic transducer 41e is
1500 × 2.925 × 10 ⁻⁶
= 4.3875 [mm]
It has propagated only to the position of. Therefore,
4.5> (4.59375−4.5) +4.3875
Thus, the ultrasonic wave transmitted from the ultrasonic transducer 41e is located outside the transmission / reception range of the ultrasonic transducer 41a.

  In order to add the reception signals of the ultrasonic transducer 41a and the ultrasonic transducer 41e thus obtained, it is necessary to match the transmission base points. Therefore, the reception signal of the ultrasonic transducer 41a is delayed by 3.2 [μs] and added to the reception signal of the ultrasonic transducer 41e. This delay can be realized by a general delay element or a delay circuit including an inductor and a capacitor.

Next, the difference in the position of the thrombus caused by delaying the ultrasonic transmission timing by 3.2 [μs] is estimated. In the blood pump of the present invention, the flow rate is set to 5 [L / min] as a standard. The flow velocity distribution in the connecting pipe 44 at this time becomes a parabolic shape according to the so-called Hagen-Poiseuille's law, and the maximum flow velocity Umax is defined as follows.
Umax = 2Q / (πr ² )
It is represented by Thereby, when the flow rate is 5 [L / min] and the radius of the connecting pipe 44 is 4.5 mm, the maximum flow velocity Umax is
Umax = 2 × (0.005 / 60) / (π × 0.0045 ² )
= 2.62 [m / sec]
It becomes.

Therefore, when the flow rate is 5 [L / min], the distance that the thrombus moves in the period of 3.2 [μs] is
2.62 × 3.2 × 10 ⁻⁶
= 8.384 × 10 ⁻⁶ [m]
= 8.384 [μm]
It becomes. This is about 1/4 or less of the ultrasonic wavelength 30 to 50 [μm], so that the ultrasonic echoes from the thrombus can be received by the ultrasonic transducers 41a and 41e ignoring the moving distance. Become.

  The same can be said for the ultrasonic transducers 41b and 41f, the ultrasonic transducers 41c and 41g, and the ultrasonic transducers 41d and 41h. Therefore, for the ultrasonic transducers 41a, 41b, 41c, and 41d, ultrasonic waves are transmitted at the same time, and the received signals obtained in the reception period (6,125 [μs] in the above example) are added. A signal obtained by the addition is defined as a signal s1.

  Next, ultrasonic waves are transmitted from the ultrasonic transducers 41e, 41f, 41g, and 41h after a predetermined time (3.2 [μs] in the above example), and a reception period (in the above example). In other words, the obtained reception signals are added to 6.125 μs). A signal obtained by the addition is defined as a signal s2. Then, the signal s1 delayed by 3.2 [μs] and the signal s2 are added to obtain a reception output Vo after the addition.

  Such transmission timing control is performed by the transmission channels (transmission channels 1 to 8) of the transmission / reception units 42a to 42h. Addition including delay is performed by the adder 43. The reception RF signal synthesized by the adder 43 is transmitted to a signal processing unit (see FIG. 2). Since the subsequent signal processing is the same as that of the first embodiment (see FIGS. 2 and 3), description thereof is omitted.

  Thus, by preparing a plurality of first and second ultrasonic transducers, the transmission / reception area can be increased and the SN ratio can be improved. Specifically, the received RF signal with an improved S / N ratio can be obtained by adding the obtained received signals to increase the transmission / reception area equivalently.

  As shown in FIG. 4, even when the thrombus 34 is not located at the center of the connecting tube 44, that is, when the thrombus 34 is located at the center of the tube wall and the tube, It falls within the detection range of the above ultrasonic transducer. Therefore, the ultrasonic echo from the thrombus 34 can be received and the thrombus can be detected.

In the first embodiment (see FIG. 3), the detection range is on one sound ray, but in the second embodiment, the detection range can be the entire region of the connection pipe 44. . In addition, the entire area can be examined in a short time. That is, in the first embodiment, since one ultrasonic transducer is used to examine up to the facing tube wall, the reception period is
4.5 × 10 ⁻³ × 2 × 2/1500
= 12 × 10 ⁻⁶ [sec]
= 12 [μs]
It is.
On the other hand, the reception period in the second embodiment is
6.125 + 3.2
= 9.325 [μs]
It becomes.

  When the flow rate is small, the time required for examining the entire area of the tube may be long. Therefore, the entire area of the tube may be scanned by transmitting and receiving ultrasonic transducers one by one in order. In this case, the circuit of the transmission / reception channel can be simplified.

Furthermore, as a modification, a configuration may be adopted in which a plurality of adjacent ultrasonic transducers are simultaneously transmitted and received.
For example, when transmitting and receiving two adjacent ultrasonic transducers simultaneously, the ultrasonic transducers 41a and 41b are simultaneously transmitted and received, and then the ultrasonic transducers 41b and 41c are simultaneously transmitted and received. Then, the ultrasonic transducers 41c and 41d are simultaneously transmitted and received. In this way, the entire area of the tube is scanned.
Even in such a configuration, the transmission / reception area can be increased by the number of CHs simultaneously transmitted / received, and therefore, a received RF signal with an improved S / N ratio can be obtained.

  Next, an example in which the blood pump device of the present invention is applied to an extracorporeal circulation type heart-lung machine will be described with reference to FIG. The artificial heart-lung machine is a device that temporarily substitutes the functions of the heart and lungs during heart surgery or the like. The blood pump device shown in FIG. 5 is the artificial heart blood pump device 1 described as the first embodiment, and the target to be applied is an extracorporeal circulation type heart-lung machine. Therefore, the blood pump device shown in FIG. 5 is assigned the same reference numeral as in FIG.

  As shown in FIG. 5, the heart-lung machine 50 includes a blood collection pump 51 that collects blood from a surgical field (a part of a human incision at the time of surgery), a blood reservoir 52, an artificial lung 53, and a blood filter 54. The blood pump device 1 is provided. Venous blood from the living body 60 is temporarily stored in the blood reservoir 52 and sent to the oxygenator 53.

The oxygenator 53 exchanges carbon dioxide (CO ₂ ) in blood sent from the blood reservoir 52 with oxygen (O ₂ ). Further, a heat exchanger 53a is provided in the oxygenator 53, and the temperature of the blood in the oxygenator 53 (body temperature adjustment) is adjusted by the heat exchanger 53a. In this manner, venous blood guided outside the body is supplied to the blood pump 2 of the blood pump device 1 as arterial blood containing oxygen by the artificial lung 53. The blood pump 2 is a pump that performs the same operation as that described with reference to FIG. 2, and the arterial blood sent from the blood pump 2 is sent to the living body 60 via the blood filter 54.

  The connection pipes 3 and 4 connected to the blood inflow port and the blood outflow port of the blood pump 2 are provided with first and second ultrasonic transducers 7 and 8 as in the embodiment shown in FIG. ing. The first and second received RF signals obtained by the first and second ultrasonic transducers 7 and 8 are sent to the transmission / reception units 25 a and 25 b of the controller 5. Since the subsequent signal processing is as described with reference to FIGS. 2 and 3, overlapping description is omitted. Then, by processing the signal by the controller 5, it is detected whether there is a thrombus in the blood sent from the oxygenator 53 or in the blood discharged (outflowed) from the blood pump 2.

  As described above, the embodiment in which the blood pump device of the present invention is applied to an artificial heart and an extracorporeal circulation type heart-lung machine has been described. In addition, this invention is not necessarily limited to the said embodiment example, In the range of the summary of this invention described in the claim, various application examples and modifications are included.

It is a block diagram which shows the structure of 1st Embodiment of the blood pump apparatus of this invention. It is explanatory drawing explaining the structure of the controller which concerns on 1st Embodiment of the blood pump apparatus of this invention, and a 1st and 2nd ultrasonic transducer. It is the figure which showed the arrangement | positioning relationship (a) of an ultrasonic transducer, a received RF signal (b), and a detection / logarithm compression signal (c). FIG. 7 is an explanatory diagram for explaining a second embodiment of the blood pump device of the present invention and showing an example in which a plurality of first and second ultrasonic transducers are used. It is a block diagram which shows the example which applied the blood pump apparatus of this invention to the heart-lung machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Artificial heart blood pump apparatus (blood pump apparatus), 2 ... Blood pump, 3 ... 1st connection pipe, 4 ... 2nd connection pipe, 5 ... Controller, 6. ..Cable, 7 ... first ultrasonic transducer, 8 ... second ultrasonic transducer, 11,12 ... Battery, 21 ... processor, 25a ... first transmission / reception unit, 25b ... 2nd transmission / reception part, 26a ... 1st signal processing part, 26a ... 2nd signal processing part, 27a ... 1st thrombus counting part, 27b ... 2nd thrombus Counting unit, 28 ... determination unit, 29 ... display unit (notification unit)

Claims (7)

A blood pump having a blood inflow port through which blood flows in and a blood outflow port through which blood flows out;
A first connecting pipe connected to the blood inlet port;
A second connecting pipe connected to the blood outflow port;
A first ultrasonic transducer disposed on an outer periphery of the first connection pipe, transmitting an ultrasonic wave to blood passing through the first connection pipe, receiving the reflected wave and converting it into an electrical signal; A second ultrasonic transducer that is disposed on the outer periphery of the second connection pipe, transmits ultrasonic waves to the blood passing through the second connection pipe, receives the reflected waves, and converts them into electrical signals; ,
A first transmitting / receiving unit that receives an electrical signal obtained by the first ultrasonic transducer and converts the electrical signal into a first RF signal; and a second transmitting / receiving unit that receives the electrical signal obtained by the second ultrasonic transducer. A second transmission / reception unit for converting to an RF signal, and a first signal for detecting the first RF signal supplied from the first transmission / reception unit and logarithmically compressing to obtain a first detection / logarithm compression signal A second signal processing unit for detecting a second RF signal supplied from the second transmission / reception unit and logarithmically compressing it to obtain a second detection / logarithm compression signal; A first thrombus counting unit that compares an output value of the first detection / logarithmic compression signal supplied from a signal processing unit with a predetermined threshold value, and counts the number of output values exceeding the threshold value as a thrombus number; The second detection / logarithmic pressure supplied from the second signal processing unit A second thrombus counter that compares the output value of the signal with the predetermined threshold and counts the number of output values exceeding the threshold as the thrombus count; the thrombus count counted by the first thrombus counter; A determination unit that compares the number of thrombus counted by the second thrombus counting unit, and a controller,
A blood pump device composed of   The determination unit determines whether a thrombus has occurred in the blood pump based on the difference between the thrombus count counted by the first thrombus count unit and the thrombus count counted by the second thrombus count unit. The blood pump device according to claim 1 for judging.   The determination unit determines whether or not the number of thrombus counted by the first thrombus counting unit or the number of thrombus counted by the second thrombus counting unit is greater than a predetermined value. The blood pump device described in 1.   Furthermore, the blood pump apparatus of Claims 1 thru | or 3 provided with the alerting | reporting part which alert | reports the judgment result by the said judgment part.   5. The notification unit issues a warning when the number of thrombus counted by the first thrombus counting unit or the number of thrombus counted by the second thrombus counting unit exceeds a predetermined value. The blood pump device described in 1.   The blood pump device according to claim 1, wherein the first ultrasonic transducer and the second ultrasonic transducer have a frequency of 30 to 50 MHz.   The blood pump device according to claim 1, wherein the blood pump is implanted in a body.

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