Ventricular assist device and control unit thereof

Abstract

The invention provides a ventricular assist device and a control unit thereof. The control unit applies suspension current to a motor based on a preset suspension current curve; obtaining a target suspension position curve, wherein the target suspension position curve is an axial displacement curve generated by the impeller according to the target suspension current curve; and according to the target suspension position curve and the preset suspension position curve, determining whether thrombus exists in the secondary flow channel of the ventricular assist device. According to the application, the suspension current of the preset suspension current curve is applied to the motor to enable the impeller to generate the corresponding suspension position curve, and then whether thrombus exists in the secondary flow channel of the ventricular assist device can be judged by comparing the suspension position curve generated by the impeller with the suspension position curve generated by the preset suspension current when no thrombus exists; the thrombus in the secondary flow channel can be detected in real time under the condition that the complexity of the mechanical design of the pump is not increased or the pump efficiency is not reduced, so that the thrombus can be conveniently and accurately scoured subsequently, and the safety of a user is improved.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a ventricular assist device and its control unit. Background Technology

[0002] Pumps used as mechanical circulation support devices include pumping mechanisms for pumping fluid from one location to another, such as centrifugal pumps and axial flow pumps for pumping blood from the heart to other parts of the body. These pumps achieve the function of pumping fluid by using an impeller disposed within the pump housing to transport fluid through the pump housing from the inlet end to the outlet end.

[0003] Currently, some mechanical circulation support devices use non-contact impeller suspension technology to solve support and energy consumption problems in highly mechanical designs. During pump operation, the high shear force generated by the high-speed rotation of the impeller can damage blood, causing blood clots to form in the bearing clearance between the suspended impeller and the pump casing, thus impairing blood compatibility and affecting pump operation. Summary of the Invention

[0004] This application provides a ventricular assist device and its control unit, which can detect in real time whether there is a thrombus in the secondary flow channel.

[0005] In a first aspect, embodiments of this application provide a control unit for a ventricular assist device, the ventricular assist device further comprising: a housing, an impeller disposed within the housing, and a motor for driving the impeller to rotate, wherein a gap region between the impeller and the housing forms a secondary flow channel; the control unit is configured to perform the following steps: A floating current is applied to the motor based on a preset floating current curve; Obtain the target suspension position curve, which is the axial displacement curve of the impeller generated according to the target suspension current curve; The presence of a thrombus in the secondary flow channel of the ventricular assist device is determined based on the target suspension position curve and the preset suspension position curve. The preset suspension position curve is the axial displacement curve of the impeller generated according to the preset suspension current curve when there is no thrombus in the secondary flow channel of the ventricular assist device.

[0006] Secondly, this application provides a ventricular assist device, the ventricular assist device comprising: case; An impeller is disposed within the housing, and a gap region exists between the impeller and the housing, the gap region forming a secondary flow channel; A motor that drives the impeller to rotate; A control unit that is communicatively connected to the motor, wherein the control unit is the control unit described in the first aspect above.

[0007] Thirdly, embodiments of this application provide a medical device, the medical device including a processor, a memory, a communication interface, and one or more programs, the one or more programs being stored in the memory and configured to be executed by the processor, the programs including instructions for performing some or all of the steps performed by the control unit described in the first aspect above.

[0008] The technical solution provided in this application involves a control unit applying a levitation current to a motor based on a preset levitation current curve; acquiring a target levitation position curve, which is the axial displacement curve of the impeller generated according to the target levitation current curve; and determining whether a thrombus exists in the secondary flow channel of the ventricular assist device based on the target levitation position curve and the preset levitation position curve, which is the axial displacement curve of the impeller generated according to the preset levitation current curve when there is no thrombus in the secondary flow channel of the ventricular assist device. This application applies a levitation current of the preset levitation current curve to the motor to generate a corresponding levitation position curve in the impeller. By comparing the levitation position curve generated by the impeller with the levitation position curve generated by the preset levitation current when there is no thrombus, it can determine whether a thrombus exists in the secondary flow channel of the ventricular assist device. This allows for real-time detection of thrombi in the secondary flow channel without increasing the complexity of the pump's mechanical design or reducing pump efficiency, facilitating subsequent precise flushing of the thrombus and increasing user safety. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the structure of a ventricular assist device provided in an embodiment of this application; Figure 2 This is a schematic diagram of an electric motor provided in an embodiment of this application; Figure 3 This is a schematic diagram of a stator provided in an embodiment of this application; Figure 4 This is a schematic diagram of a control unit performing thrombus detection according to an embodiment of this application; Figure 5 This is a schematic diagram of a sine wave floating current curve provided in an embodiment of this application; Figure 6 This is a schematic diagram of a floating current curve as a square wave provided in an embodiment of this application; Figure 7This is a schematic diagram of the impeller's levitation position when the levitation current curve is a sine wave, provided in an embodiment of this application. Figure 8 This is a schematic diagram of the impeller's levitation position when the levitation current curve is a sine wave, as provided in another embodiment of this application. Figure 9 This is a schematic diagram of the impeller's levitation position when the levitation current curve is a sine wave, as provided in another embodiment of this application. Figure 10 This is a schematic diagram of the impeller's levitation position when the levitation current curve is a square wave, provided in an embodiment of this application. Figure 11 This is a schematic diagram of the impeller's levitation position when the levitation current curve is a square wave, as provided in another embodiment of this application. Figure 12 This is a schematic diagram of the impeller's levitation position when the levitation current curve is a square wave, as provided in another embodiment of this application. Figure 13 This is a schematic diagram of an impeller partitioning region provided in an embodiment of this application; Figure 14 This is a schematic diagram of the structure of a medical device provided in an embodiment of this application. Detailed Implementation

[0011] To help those skilled in the art better understand the technical solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the description of the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, software, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but also includes steps or units not listed, or other steps or units inherent to such processes, methods, products, or apparatus.

[0013] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0014] In this article, "proximal" is defined as the end closer to the operator; "distal" is defined as the end farther from the operator, that is, the end closer to the patient's heart.

[0015] The medical device involved in this application may be a ventricular assist device (VAD), such as an interventional ventricular assist device or an implantable ventricular assist device; the ventricular assist device may be a left ventricular assist device, a right ventricular assist device, or a biventricular assist device; the ventricular assist device may include at least one blood pump, wherein the blood pump may be a centrifugal pump, an axial flow pump, etc.

[0016] A ventricular assist device (VAD) can be attached to the heart via a ventricular connection assembly (such as a top ring, ventricular cuff, or ventricular linker). This assembly can be sutured to the heart and connected to a blood pump. The other end of the blood pump can be connected to the ascending aorta via an outlet tube and / or an artificial blood vessel connected to the outlet tube. This allows the VAD to effectively transfer blood from the weakened ventricle and propel it into the aorta, thereby circulating it to the rest of the patient's vascular system and providing ventricular support.

[0017] like Figures 1-3 As shown, the ventricular assist device 100 includes a housing assembly with an inlet pipe and an impeller 20 for propelling fluid. The housing assembly includes a first housing and a second housing connected to the first housing. The first housing and the second housing together form a chamber 10. The housing assembly also has a fluid inlet 14 and a fluid outlet 15 communicating with the chamber 10, and the fluid inlet 14 is located on the first housing. The impeller 20 can levitate and rotate within the chamber 10. The rotation of the impeller 20 generates centrifugal force to transport fluid, allowing fluid to enter the chamber 10 from the fluid inlet 14 and exit from the fluid outlet 15. The levitation and rotation of the impeller 20 means that the impeller 20 does not contact the chamber wall of the chamber 10 during rotation.

[0018] The ventricular assist device 100 also includes a motor 30 and a sensor 40 for driving the impeller 20 to levitate and rotate. The second housing includes a first sidewall 11 and a second sidewall 12. The motor 30 includes a stator 31 and a rotor 32 positioned on either side of the first sidewall 11. The stator 31 is fixed to the outer side of the first sidewall 11 relative to the chamber 10, while the rotor 32 is located inside the chamber 10. Furthermore, the rotor 32 is fixedly connected to the impeller 20. When the stator 31 drives the rotor 32 to rotate within the chamber 10, the impeller 20 also rotates synchronously within the chamber 10 along with the rotor 32. The rotation of the impeller 20 can pressurize the fluid within the chamber 10, giving it greater pressure and thus achieving the fluid pressurization effect of a blood pump.

[0019] It should be noted that, in Figure 1 In one embodiment, the first sidewall 11 and the second sidewall 12 are arranged in a parallel configuration, and the rotation axis 21 of the impeller 20 is perpendicular to both the first sidewall 11 and the second sidewall 12.

[0020] The impeller 20 is annular and has a central hole 25. The fluid inlet 14 is directly opposite the central hole 25 of the impeller 20. The impeller 20 also includes opposing first surfaces 22 and second surfaces 23, and flow channels 24. The first surface 22 is opposite to the second sidewall 12, and the second surface 23 is opposite to the first sidewall 11. The central hole 25 penetrates through the first surface 22 and the second surface 23. There are multiple flow channels 24, which extend radially along the annular impeller 20. The flow channels 24 are disposed between the first surface 22 and the second surface 23. The flow channels 24 communicate with the central hole 25. After the fluid enters the central hole 25 of the impeller 20 from the fluid inlet 14, it flows out of the impeller 20 from the flow channels 24, which serve as the main flow channels for the fluid. Adjacent flow channels 24 are separated by the blades of the impeller 20. As the impeller 20 rotates within the flow channels 24, the fluid velocity increases, thereby achieving a pressurization effect, and then flows out from the fluid outlet 15. The first surface 22 is located on the side of the impeller 20 facing the second sidewall 12. The rotor 32 is housed within the impeller 20; specifically, the rotor 32 is disposed within the impeller 20 and close to the second surface 23. When the impeller 20 is suspended and rotating within the chamber 10, there is a gap between the first surface 22 of the impeller 20 and the second sidewall 12, and a gap between the second surface 23 of the impeller 20 and the first sidewall 11 of the second housing. Secondary flow channels are formed between the first surface 22 and the second sidewall 12, and between the second surface 23 and the first sidewall 11. After fluid flows into the impeller 20, a small portion of the fluid flows out from the flow channel 24 of the impeller 20 and does not flow directly to the fluid outlet 15, but instead re-enters the main flow channel through the secondary flow channel.

[0021] The stator 31 includes n winding units, with three winding units forming a three-phase winding. The motor 30 is driven by inputting three-phase alternating current (AC) into each three-phase winding, with the phase difference between the three phases being 120 degrees. Sensors 40 are positioned opposite the rotor 32; there are n sensors 40, and these n sensors 40 and the n winding units are arranged symmetrically in a circle.

[0022] In this application, n is a multiple of 3, that is, n can be 3, 6, 9, etc. After satisfying the above structure, regardless of whether there are 3, 6, 9 or more winding units, the rotor 32 can be driven to rotate and levitate in real time to realize the operation of the motor.

[0023] The following description uses an example of n=6, where the stator comprises 6 winding units, to illustrate the specific scheme of this application. The specific implementation schemes for n=3, n=9, etc., are the same as the specific implementation scheme for n=6, and will not be repeated here.

[0024] like Figure 3 As shown, the stator 31 is generally annular and includes six winding units 310. These six winding units 310 are arranged symmetrically around a circumference. For example, each winding unit 310 includes stator teeth 311 and stator coils 312. The stator 31 includes two three-phase windings. The winding units in these two three-phase windings are evenly and alternately arranged along a circle. That is, the winding units in the first three-phase winding are adjacent to the winding units in the second three-phase winding, and the U-phase, V-phase, and W-phase winding units in the first three-phase winding are respectively arranged opposite to the U-phase, V-phase, and W-phase winding units in the second three-phase winding, with a 180° interval. Specifically, the U-phase winding unit of the first three-phase winding is opposite to the U-phase winding unit of the second three-phase winding, with a 180° interval; the V-phase winding unit of the first three-phase winding is opposite to the V-phase winding unit of the second three-phase winding, with a 180° interval; and the W-phase winding unit of the first three-phase winding is opposite to the W-phase winding unit of the second three-phase winding, with a 180° interval. Figure 3 As shown, winding units 3101, 3103, and 3105 are all first winding units, and winding units 3101, 3103, and 3105 are the three phases of the first three-phase winding; winding units 3102, 3104, and 3106 are all defined as second winding units, and winding units 3102, 3104, and 3106 are the three phases of the second winding unit; in the figure, winding units 3101 and 3104 are arranged opposite to each other, winding units 3102 and 3105 are arranged opposite to each other, and winding units 3103 and 3106 are arranged opposite to each other.

[0025] The ventricular assist device 100 also includes a control unit 33, which is plate-shaped, specifically a circular PCB circuit board. The PCB circuit board may include an upper surface and a lower surface, connected by a flexible data cable. The upper surface is located on the side of the stator 31 facing the rotor 32, and the lower surface is located on the side of the stator 31 away from the rotor 32. A sensor 40 is disposed on either the upper or lower surface of the control unit 33 and is electrically connected to the control unit 33. For example... Figure 2 The sensors 40 are disposed on the upper surface of the control unit 33. Six sensors 40 are respectively located between every two adjacent stator teeth 312. The sensors 40 are used to measure the axial distance between the rotor 32 and the stator 31, and transmit the measured distance to the control unit 33.

[0026] Furthermore, the control unit 33 is electrically connected to each winding unit 310 in the stator 31. Specifically, the control unit 33 can determine the suspension position of the rotor 32 in the impeller 20 relative to the stator 31 based on the received distance signal, and thus determine the axial position of the impeller 20 within the chamber 10. By controlling the power of the stator 31, the control unit 33 can control the magnetic force between the stator 31 and the rotor 32, thereby achieving the effect of controlling the rotational speed and suspension position of the rotor 32 in the impeller 20 by the stator 31.

[0027] The control unit 33 includes hardware and software for controlling various aspects of the operation of the motor 30. The control unit 33 can be coupled to the motor 30 via an interface to collect at least one piece of data from the motor 30. This at least one piece of data may include the measured current flowing through the stator 31, data measured by the sensor 40, the motor speed, the pressure difference across the pump, flow pulsation, fluid velocity, etc.

[0028] For example, the sensor 40 can be a Hall sensor, which can be used to measure the distance between the impeller 20 and the first sidewall 11, and transmit this distance value to the control unit 33 via a flexible data line. Specifically, the Hall sensor is positioned relative to the rotor 32 on the impeller 20 via a path. As the impeller 20 rotates, causing the S and N poles of the rotor to alternately pass near the Hall sensor, the signal level of the Hall sensor, representing the magnetic flux intensity, changes sinusoidally. Therefore, by detecting the time change of the output signal of the Hall sensor, the positional relationship between the rotor 32 and the stator 31 can be detected, and the rotational speed of the impeller 20 with current flowing through the stator 31 can be calculated.

[0029] The high shear force during the rotation of impeller 20 can damage blood cells, causing more platelets to remain in the secondary flow channel. This leads to platelet aggregation and adhesion within the secondary flow channel, resulting in thrombus formation. The threat of thrombotic complications caused by the ventricular assist device 100 remains unresolved. Intra-pump thrombus formation can lead to serious complications, making early detection and determination of thrombus location crucial for the reliability of the ventricular assist device 100.

[0030] Based on this, the control unit 33 in this application applies a preset levitation current to the motor 30, causing the impeller 20 to periodically vibrate. The axial displacement signal of the impeller 20 is detected by the sensor 40. By pre-calibrating the axial position change generated by the levitation current, the levitation position change curve under the levitation excitation current change in the thrombus-free state can be obtained. When there is a thrombus in the secondary flow channel of the ventricular assist device 100, the amplitude of the impeller's levitation position on the side with the thrombus will be less than or greater than the displacement amplitude calibrated when there is no thrombus. Therefore, by comparing the magnitude of the impeller's levitation position amplitude, the presence of a thrombus in the secondary flow channel of the ventricular assist device 100 can be detected in real time, thereby determining the specific location of the thrombus.

[0031] Based on the above description, this application will now be described from the perspective of method examples.

[0032] Please see Figure 4 , Figure 4 This application provides a schematic diagram of a control unit performing thrombus detection, applicable to, for example... Figures 1-3 The ventricular assist device shown. Figure 4 As shown, the control unit performs the following steps.

[0033] S410. Apply a floating current to the motor based on a preset floating current curve.

[0034] In this application, the control unit 33 applies a levitation current to the motor 30 to induce periodic vibration in the impeller 20. The sensor 40 detects the axial position change signal of the impeller 20. The levitation position change generated by the levitation excitation current can be pre-calibrated to obtain the impeller levitation position change curve under thrombus-free conditions. When a thrombus is present in the secondary flow channel, on the side with the thrombus, the amplitude of the impeller 20's levitation position will be less than or greater than the calibrated amplitude, and the phase of the impeller's levitation position amplitude will lead the phase of the levitation excitation current amplitude. Therefore, by comparing the levitation position of the impeller 20 after applying the preset levitation current with the preset calibrated levitation position, it can be determined whether a thrombus exists in the secondary flow channel of the ventricular assist device 100.

[0035] The waveform of the preset levitation current curve is either a sine wave or a square wave. The control unit 33 applies a levitation current to the motor 30, and the motor 30 controls the axial position of the impeller 20 (i.e., the levitation position of the impeller 20 within the chamber 10) according to the levitation current. The waveform of the preset levitation current curve can be a sine wave, a square wave, or other waveforms, such as a saddle shape or a trapezoidal shape. This levitation current causes the impeller 20 to undergo periodic up-and-down axial movement, thereby causing periodic axial movement within the chamber 10.

[0036] Taking sine waves and square waves as examples, the preset floating current curve is a sine wave waveform as follows: Figure 5 As shown, the floating current reaches its maximum value at time t0 and its minimum value at time t1. The preset floating current curve is a square wave, as shown in the figure. Figure 6 As shown, the floating current changes at time t2, from its maximum value to its minimum value; and at time t3, the floating current changes again, from its minimum value to its maximum value.

[0037] S420. Obtain the target suspension position curve, wherein the target suspension position curve is the axial displacement curve generated by the impeller according to the target suspension current curve.

[0038] The control unit 33 employs Field-Oriented Control (FOC) to control the starting and operation of the motor 30. First, the measured three-phase currents are transformed into a two-axis coordinate system via Clarke and Park transformations to generate orthogonal currents. (Torque current) and DC current (Suspension current). This orthogonal current controls the torque, causing the impeller 20 to rotate; the DC current controls the magnetic force between the rotor 32 and the stator 31 to control the axial position of the impeller 20. The control unit 33 applies a preset suspension current to the motor 30, which causes the impeller 20 to move axially periodically. The sensor 40 detects the change in the axial position of the impeller 20 and forms a target suspension position curve. The waveform of the target suspension position curve changes with the waveform of the preset suspension current curve.

[0039] S430. Determine whether there is a thrombus in the secondary flow channel of the ventricular assist device based on the target suspension position curve and the preset suspension position curve. The preset suspension position curve is the axial displacement curve generated by the impeller according to the preset suspension current curve when there is no thrombus in the secondary flow channel of the ventricular assist device.

[0040] The waveform of the suspension position curve of impeller 20 is determined by the waveform of the applied suspension current curve. When the waveform of the preset suspension current curve is a sine wave, the waveform of the suspension position curve of impeller 20 is also a sine wave; when the waveform of the preset suspension current curve is a square wave, the waveform of the suspension position curve of impeller 20 is also a square wave.

[0041] The control unit 33 pre-acquires the suspension position curve of the impeller 20 when a preset suspension current is applied in the secondary flow channel of the ventricular assist device 100 without thrombus, and calibrates it as the preset suspension position curve. When a thrombus is present in the secondary flow channel of the ventricular assist device 100, the presence of the thrombus prevents the impeller 20 from reaching the preset axial position, resulting in the amplitude of the suspension position of the impeller 20 on the side with the thrombus being less than or greater than the amplitude of the suspension position calibrated when there is no thrombus. Furthermore, when the waveform of the preset suspension current curve is a sine wave, on the side with the thrombus, the amplitude phase of the suspension position of the impeller 20 leads the amplitude phase of the preset suspension current.

[0042] The preset floating position curve reaches a first floating position at a first time and a second floating position at a second time. The first floating position is the maximum floating position in the preset floating position curve, and the second floating position is the minimum floating position in the preset floating position curve.

[0043] Specifically, when there is no thrombus in the secondary flow channel of the ventricular assist device 100, when a preset floating current curve is applied to the motor 30, the motor 30 controls the impeller 20 to generate a floating position curve according to the preset floating current curve.

[0044] For example, the waveform of the preset floating current curve is as follows: Figure 5 When the sine wave is shown, the waveform of the suspension position curve of the impeller 20 is also a sine wave. The impeller 20 reaches the maximum suspension position L0 at time t0 and the minimum suspension position L1 at time t1.

[0045] For example, the waveform of the preset floating current curve is as follows: Figure 6 As shown in the square wave diagram, the waveform of the suspension position curve of impeller 20 is also a square wave. During the period from 0 to t2, impeller 20 remains at the maximum suspension position L2. At time t2, impeller 20 moves from the maximum suspension position L2 to the minimum suspension position L3 and remains at the minimum suspension position L3 during the period from t2 to t3.

[0046] Optionally, in determining whether a thrombus exists in the secondary flow path of the ventricular assist device based on the target suspension position curve and the preset suspension position curve, the control unit performs the following steps: determining a third suspension position and a fourth suspension position from the target suspension position curve, wherein the third suspension position is the maximum suspension position in the target suspension position curve and the fourth suspension position is the minimum suspension position in the target suspension position curve; calculating a first difference and a second difference, wherein the first difference is the difference between the first suspension position and the third suspension position, and the second difference is the difference between the second suspension position and the fourth suspension position; and determining whether a thrombus exists in the secondary flow path of the ventricular assist device based on the first difference and the second difference.

[0047] See Figures 7 to 12 When a thrombus is present in the secondary flow channel, the impeller 20 cannot reach the preset suspension position due to the presence of the thrombus. Specifically, if a thrombus is present in the secondary flow channel formed between the second sidewall 12 of the housing and the first surface 22 of the impeller 20, the impeller 20 cannot reach the maximum suspension position L0 or the maximum suspension position L2; if a thrombus is present in the secondary flow channel formed between the first sidewall 11 of the housing and the second surface 23 of the impeller 20, the impeller 20 cannot reach the minimum suspension position L1 or the minimum suspension position L3. Therefore, by comparing the actual suspension position of the impeller 20 with the preset suspension position, it can be determined whether a thrombus is present in the current secondary flow channel.

[0048] The control unit 33 obtains the maximum and minimum floating positions reached by the impeller 20 from the target floating position curve. By comparing the maximum and minimum floating positions in the target floating position curve with those in the preset floating position curve, it can be determined whether there is a thrombus in the secondary flow channel. Specifically, the control unit 33 determines the floating position of the maximum value (i.e., the third floating position) and the floating position of the minimum value (i.e., the fourth floating position) from the target floating position curve. The difference between the first and third floating positions is calculated to obtain the first difference; the difference between the fourth and second floating positions is calculated to obtain the second difference. Based on the magnitude of the first and second differences, it can be determined whether there is a thrombus in the secondary flow channel formed between the second sidewall 12 of the housing and the first surface 22 of the impeller 20 and / or the secondary flow channel formed between the first sidewall 11 of the housing and the second surface 23 of the impeller 20, and the size of any thrombus present.

[0049] Wherein, the larger the first difference and / or the second difference, the larger the thrombus. A larger first difference indicates a larger thrombus thickness (volume) in the secondary flow channel formed between the second sidewall 12 of the housing and the first surface 22 of the impeller 20, hindering the axial movement of the impeller 20 to the preset maximum suspension position L0. The difference between the maximum suspension position L0 and the maximum suspension position L2 is the axial height of the thrombus. A larger second difference indicates a larger thrombus thickness (volume) in the secondary flow channel formed between the first sidewall 11 of the housing and the second surface 23 of the impeller 20, hindering the axial movement of the impeller 20 to the preset minimum suspension position L1. The difference between the minimum suspension position L1 and the minimum suspension position L3 is the axial height of the thrombus.

[0050] The amplitude difference and phase difference between the target suspension position and the preset suspension position of impeller 20 increase with the increase of thrombus. This method can be used to determine which side of the secondary flow channel of impeller 20 has thrombus distributed.

[0051] In one possible example, the waveform of the preset floating current curve is a sine wave. Regarding determining whether a thrombus exists in the secondary flow channel of the ventricular assist device based on the first difference and the second difference, the control unit performs the following steps: acquiring a third time point and a fourth time point, where the third time point corresponds to the third floating position and the fourth time point corresponds to the fourth floating position; if the first difference is greater than 0 and the third time point is earlier than the first time point, then it is determined that a thrombus exists in the secondary flow channel formed between the surface of the impeller away from the motor and the housing in the ventricular assist device; if the second difference is greater than 0 and the fourth time point is earlier than the second time point, then it is determined that a thrombus exists in the secondary flow channel formed between the surface of the impeller facing the motor and the housing in the ventricular assist device; otherwise, no thrombus exists in the secondary flow channel of the ventricular assist device.

[0052] Specifically, when the waveform of the preset levitation current curve is a sine wave, the impeller 20, based on the sine wave excitation, experiences vertical axial movement with the same period as the preset excitation current curve. The control unit 33 obtains the times when the impeller 20 reaches its maximum levitation position and its minimum levitation position, i.e., the third and fourth times, from the target levitation position curve. When a thrombus is present in the secondary flow channel, the impeller 20 will not only fail to reach the preset maximum levitation position L0 but will also reach its maximum levitation position ahead of time t0, and / or will not only fail to reach the preset minimum levitation position L1 but will also reach its minimum levitation position ahead of time t1.

[0053] For example, when a thrombus exists in the secondary flow channel formed between the second sidewall 12 and the first surface 22 of the impeller 20, such as Figure 7As shown, the impeller 20 reaches its maximum suspension position La at time ta, which is Δt1 earlier than the time t0 when the maximum suspension position L0 is reached in the preset suspension position curve, and the impeller 20 remains at the suspension position La for the time Δt1. The difference ΔLa between the suspension position L0 and the suspension position La is the axial thickness of the maximum thrombus in the secondary flow channel. When a thrombus exists in the secondary flow channel formed between the first sidewall 11 and the second surface 23 of the impeller 20, such as Figure 8 As shown, the impeller 20 reaches the minimum suspension position Lb at time tb, which is Δt2 earlier than the time t1 when the minimum suspension position L1 is reached in the preset suspension position curve, and the impeller 20 remains in the suspension position Lb for Δt2. The difference ΔLb between the suspension position L1 and the suspension position Lb is the axial thickness of the maximum thrombus in the secondary flow channel. When thrombi exist in both the secondary flow channels formed between the second sidewall 12 and the first surface 22 of the impeller 20 and between the first sidewall 11 and the second surface 23 of the impeller 20, such as Figure 9 As shown, impeller 20 reaches its maximum suspension position La at time ta and its minimum suspension position Lb at time tb. That is, it reaches its maximum suspension position La △t1 earlier than time t0 when it reaches its maximum suspension position L0 in the preset suspension position curve, and it reaches its minimum suspension position Lb △t2 earlier than time t1 when it reaches its minimum suspension position L1 in the preset suspension position curve. Furthermore, impeller 20 remains at suspension position La for △t1 and at suspension position Lb for △t2. △La is the axial thickness of the maximum thrombus in the secondary flow channel on the first surface 22 side of impeller 20, and △Lb is the axial thickness of the maximum thrombus in the secondary flow channel on the second surface 23 side of impeller 20.

[0054] In another possible example, the waveform of the preset floating current curve is a square wave. Regarding determining whether a thrombus exists in the secondary flow channel of the ventricular assist device based on the first difference and the second difference, the control unit performs the following steps: if the first difference is greater than 0, it is determined that a thrombus exists in the secondary flow channel formed between the surface of the impeller away from the motor and the housing in the ventricular assist device; if the second difference is greater than 0, it is determined that a thrombus exists in the secondary flow channel formed between the surface of the impeller facing the motor and the housing in the ventricular assist device; otherwise, no thrombus exists in the secondary flow channel of the ventricular assist device.

[0055] Specifically, when the waveform of the preset levitation current curve is a square wave, the impeller 20 is excited by the square wave and undergoes vertical axial movement with the same period as the preset excitation current curve. The control unit 33 obtains the maximum levitation position and the minimum levitation position of the impeller 20 from the target levitation position curve. When a thrombus is present in the secondary flow channel, the impeller 20 will not reach the preset maximum levitation position 20, and / or will not only fail to reach the preset minimum levitation position L3.

[0056] For example, when a thrombus exists in the secondary flow channel formed between the second sidewall 12 and the first surface 22 of the impeller 20, such as Figure 10 As shown, the impeller 20 remains in the suspension position Lc during the 0-t2 period, which is smaller than the suspension position L2 reached in the preset suspension position curve. The difference ΔLc between the suspension position L2 and the suspension position Lc is the axial thickness of the maximum thrombus in the secondary flow channel. When a thrombus exists in the secondary flow channel formed between the first sidewall 11 and the second surface 23 of the impeller 20, as... Figure 11 As shown, the impeller 20 remains in the suspension position Ld during the t2-t3 period, which is smaller than the minimum suspension position L3 in the preset suspension position curve. The difference ΔLd between the suspension position L3 and the suspension position Ld is the axial thickness of the maximum thrombus in the secondary flow channel. When thrombi exist in both the secondary flow channels formed between the second sidewall 12 and the first surface 22 of the impeller 20 and between the first sidewall 11 and the second surface 23 of the impeller 20, such as Figure 12 As shown, impeller 20 remains in suspension position Lc during the 0-t2 period and in suspension position Ld during the t2-t3 period, which is smaller than the maximum suspension position L2 and the minimum suspension position L3 in the preset suspension position curve. △Lc is the axial thickness of the maximum thrombus in the secondary flow channel on the first surface 22 side of impeller 20, and △Ld is the axial thickness of the maximum thrombus in the secondary flow channel on the second surface 23 side of impeller 20.

[0057] The control unit is also used to perform the following steps: controlling the suspending current applied to the winding unit to detect the specific location of the thrombus in the secondary flow channel; controlling the impeller tilt and adjusting the rotation speed of the ventricular assist device according to the specific location of the thrombus to flush out the thrombus.

[0058] When a thrombus is detected in the secondary flow channel by the excitation current, the control unit 33 can determine the specific location of the thrombus by tilting the impeller 20 to facilitate precise flushing of the thrombus. The impeller 20 is divided into regions based on the winding unit, and the levitation current flowing through the winding unit is controlled to tilt the impeller 20 towards a specific region to determine whether a thrombus exists in that region.

[0059] Taking a stator 31 comprising six winding units as an example, the impeller 20 is divided into six regions based on the number of winding units, such as... Figure 13 As shown, the impeller 20 is divided into regions a, b, c, d, e, and f, each corresponding to a winding unit: region a corresponds to winding unit 3101, region b to winding unit 3102, region c to winding unit 3103, region d to winding unit 3104, region e to winding unit 3105, and region f to winding unit 3106. Winding units spaced 180° apart form tilted winding unit groups; specifically, winding units 3101 and 3104 form one tilted winding unit group, winding units 3102 and 3105 form another, and winding units 3103 and 3106 form yet another. The control unit 33 sequentially controls the impeller to tilt towards one of these six regions. For example, when tilted towards region a, the suspension position of the impeller corresponding to region a is smaller than the suspension positions of the impellers corresponding to other regions; correspondingly, the suspension position of the impeller corresponding to region d is larger than the suspension positions of the impellers corresponding to other regions. That is, the suspension position of region a is small and the suspension position of region d is large, causing the impeller 20 to tilt towards region a. By tilting the impeller 20 towards different regions, the distribution area of ​​the thrombus can be determined, thereby providing location for flushing the thrombus.

[0060] Optionally, when a thrombus is present in the secondary flow channel of the ventricular assist device, the control unit is further configured to perform the following steps: at time i, decrease the floating current applied to the i-th first winding unit and simultaneously increase the floating current applied to the i-th second winding unit, wherein the i-th first winding unit is any one of the n winding units, and the i-th second winding unit is a winding unit among the n winding units that is 180° away from the i-th first winding unit, and i is a positive integer less than or equal to n; obtain a first floating position, wherein the first floating position is the minimum floating position of the n winding units at time i; if the first floating position is greater than a preset floating position, determine that a thrombus is present in the secondary flow channel corresponding to the i-th first winding unit; set i = i + 1, and repeat the above steps until i = n.

[0061] The control unit 33 sequentially applies levitation current to the winding units to control the impeller 20 to tilt towards different regions. When a thrombus is detected in the secondary flow channel formed between the first sidewall 11 and the second surface 23 of the impeller 20, the control unit 33 sequentially controls the impeller 20 to tilt towards regions a, b, c, d, e, and f. For example, when controlling the impeller 20 to tilt towards region a, the control unit 33 reduces the levitation current of the winding unit 3101 corresponding to region a and simultaneously increases the levitation current of the winding unit 3104 in the same tilted winding unit group as the winding unit 3101, so that the axial magnetic force generated by the winding unit 3101 and the rotor 32 is smaller than the axial magnetic force generated by the winding unit 3104 and the rotor 32, the levitation position of the impeller corresponding to region a is small, while the levitation position of the impeller corresponding to region d is large, causing the impeller 20 to tilt towards region a.

[0062] For example, taking the presence of a thrombus in the secondary flow channel formed between the first sidewall 11 and the second surface 23 of the impeller 20 as an example, the control unit sequentially controls the impeller 20 to tilt counterclockwise from region a to region f to determine the specific location of the thrombus. When detecting region a, the floating current of winding unit 3101 is reduced and the floating current of winding unit 3104 is increased, controlling the impeller 20 to tilt towards region a to the allowable safe distance position of the impeller 20. If the impeller cannot reach the preset floating position, it is considered that there is a thrombus in region a. If the impeller 20 can reach the preset floating position normally, it is considered that there is no thrombus in region a. The control unit 33 then controls the tilting of region b, reducing the floating current of winding unit 3102 and increasing the floating current of winding unit 3104, controlling the impeller 20 to tilt towards region b to the preset floating position of the impeller 20. If the impeller 20 cannot reach the preset floating position, it is considered that there is a thrombus in region b. If impeller 20 can reach the preset suspension position normally, it is assumed that there is no thrombus in region b. Control unit 33 continues to control the tilt of region c, reducing the suspension current of winding unit 3103 and increasing the suspension current of winding unit 3106, controlling impeller 20 to tilt towards region c to a position with an allowable safe distance. If impeller 20 cannot reach the preset suspension position, it is assumed that there is a thrombus in region c. If impeller 20 can reach the preset suspension position normally, it is assumed that there is no thrombus in region c. Control unit 33 continues to control the tilt of region d, reducing the suspension current of winding unit 3104 and increasing the suspension current of winding unit 3101, controlling impeller 20 to tilt towards region d to a position with an allowable safe distance. If impeller 20 cannot reach the preset suspension position, it is assumed that there is a thrombus in region d. If impeller 20 can reach the preset suspension position normally, it is assumed that there is no thrombus in region d. Control unit 33 continues to control the tilt of region e, reducing the suspension current of winding unit 3105 and increasing the suspension current of winding unit 3102, controlling impeller 20 to tilt towards region e to a position with an allowable safe distance from impeller 20. If impeller 20 cannot reach the preset suspension position, it is assumed that there is a thrombus in region e. If impeller 20 can reach the preset suspension position normally, it is assumed that there is no thrombus in region e. Control unit 33 continues to control the tilt of region f, reducing the suspension current of winding unit 3106 and increasing the suspension current of winding unit 3101, controlling impeller 20 to tilt towards region f to a position with an allowable safe distance from impeller 20. If impeller 20 cannot reach the preset suspension position, it is assumed that there is a thrombus in region f.

[0063] Furthermore, if the impeller 20 can reach the preset suspension position normally when tilted to region f in sequence, it is considered that there is no thrombus in the secondary flow channel formed between the first sidewall 11 and the second surface 23 of the impeller 20, and the thrombus detected by the control unit 33 may be washed away or there may be an error in thrombus detection.

[0064] The preset suspension position can be set as the allowable safe distance position of the impeller 20. The allowable safe distance position is between 0.05mm and 0.1mm between the first sidewall 11 and the second surface 23 of the impeller 20, and between the second sidewall 12 and the first surface 22 of the impeller 20.

[0065] Furthermore, the control unit is also used to perform the following steps: when there is a thrombus at the secondary flow channel corresponding to the i-th first winding unit, increase the floating current applied to the i-th first winding unit, decrease the floating current applied to the i-th second winding unit, and control the rotation speed of the ventricular assist device to pulsate in order to flush the thrombus.

[0066] Once the specific area where the thrombus is distributed within the secondary flow channel is determined, the control unit can flush the thrombus. In this application, to accelerate the flushing of the thrombus, the control unit 33 controls the impeller 20 to tilt diagonally toward the area containing the thrombus while controlling the rotational speed pulsation of the ventricular assist device 100 to flush the thrombus, so as to create a pressure differential in the area containing the thrombus.

[0067] For example, taking the presence of a thrombus in region a as an example, the control unit 33 controls the rotational speed pulsation of the ventricular assist device 100 while increasing the floating current of the winding unit 3101 corresponding to region a and decreasing the floating current of the winding unit 3104 in the same group, causing the impeller 20 to tilt towards region d to a preset floating position. At this time, the gap between the first sidewall 11 and the second surface 23 of the impeller 20 in region a reaches its maximum. By adjusting the rotational speed of the impeller 20 to have speed pulsation during operation, a pulsating pressure difference is obtained in region a, increasing the flushing force on the thrombus.

[0068] In this application, the control unit 33 controls the application of a preset levitation current to the motor 30. By comparing the actual levitation position of the impeller 20 with the preset levitation position, it determines whether there is a thrombus in the secondary flow channel of the ventricular assist device 100. When a thrombus exists, the distribution area of ​​the thrombus in the secondary flow channel is determined by sequentially controlling the tilt of different areas of the impeller 20. Furthermore, by controlling the tilt of the impeller 20, the gap between the areas with thrombi in the secondary flow channel is maximized. At the same time, the impeller 20 is controlled to pulsate its rotation speed, forming a pulsating pressure difference in the area with thrombi, increasing the flushing force on the thrombus, thereby accelerating the flushing away of the thrombus.

[0069] As can be seen, this application proposes a control unit for a ventricular assist device. The control unit applies a levitation current to the motor based on a preset levitation current curve; acquires a target levitation position curve, which is the axial displacement curve of the impeller generated according to the target levitation current curve; and determines whether there is a thrombus in the secondary flow channel of the ventricular assist device based on the target levitation position curve and the preset levitation position curve, which is the axial displacement curve of the impeller generated according to the preset levitation current curve when there is no thrombus in the secondary flow channel of the ventricular assist device. This application applies a levitation current of the preset levitation current curve to the motor to make the impeller generate a corresponding levitation position curve. Then, by comparing the levitation position curve generated by the impeller with the levitation position curve generated by the preset levitation current when there is no thrombus, it can determine whether there is a thrombus in the secondary flow channel of the ventricular assist device. This enables real-time detection of thrombi in the secondary flow channel without increasing the complexity of the pump mechanical design or reducing the pump efficiency, facilitating subsequent precise flushing of the thrombus and increasing user safety. The above primarily describes the solutions of the embodiments of this application from the perspective of the method execution process. It is understood that, in order to achieve the above functions, the network device includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments provided herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0070] For example, this application provides a ventricular assist device, the ventricular assist device comprising: case; An impeller is disposed within the housing, and a gap region exists between the impeller and the housing, the gap region forming a secondary flow channel; A motor that drives the impeller to rotate; A control unit that is communicatively connected to the motor, wherein the control unit is the control unit described above.

[0071] For example, this application also provides a medical device that includes the control unit 33 or the ventricular assist device 100 described above.

[0072] The control unit 33 of each of the above solutions has the function of implementing the corresponding steps performed by the medical device in the above method; the function can be implemented by hardware or by hardware executing corresponding software.

[0073] Please see Figure 14 , Figure 14 This is a schematic diagram of the structure of a medical device provided in an embodiment of this application. The medical device includes: one or more processors, one or more memories, one or more communication interfaces, and one or more programs; the one or more programs are stored in the memories and configured to be executed by the one or more processors.

[0074] The above procedure includes instructions for performing the following steps: A floating current is applied to the motor based on a preset floating current curve; Obtain the target suspension position curve, which is the axial displacement curve of the impeller based on the target suspension current curve; The presence of thrombus in the secondary flow channel of the ventricular assist device is determined based on the target suspension position curve and the preset suspension position curve. The preset suspension position curve is the axial displacement curve of the impeller generated according to the preset suspension current curve when there is no thrombus in the secondary flow channel of the ventricular assist device.

[0075] All relevant content in each scenario involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0076] It should be understood that the aforementioned memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store information about the device type.

[0077] In the embodiments of this application, the processor of the above-described device may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0078] It should be understood that "at least one" in the embodiments of this application refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0079] Furthermore, unless otherwise stated, the ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects and are not used to limit the order, timing, priority, or importance of multiple objects. For example, "first information" and "second information" are only used to distinguish different information and do not indicate differences in the content, priority, sending order, or importance of these two types of information.

[0080] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly manifested as execution by a hardware processor, or as a combination of hardware and software units within the processor. The software units can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor executes the instructions in the memory, combining them with its hardware to complete the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0081] This application also provides a computer storage medium storing a computer program for electronic data interchange, which causes a computer to perform some or all of the steps of any of the methods described in the above method embodiments.

[0082] This application also provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program operable to cause a computer to perform some or all of the steps of any of the methods described in the above method embodiments. This computer program product can be a software installation package.

[0083] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0084] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0085] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0086] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of this application, depending on actual needs.

[0087] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0088] If the aforementioned integrated units are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or TRP, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0089] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage device, which may include flash drives, ROM, RAM, magnetic disks, or optical disks, etc.

[0090] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A control unit of a ventricular assist device, characterized in that The ventricular assist device further includes: a housing, an impeller disposed within the housing, and a motor for driving the impeller to rotate; the gap region between the impeller and the housing forms a secondary flow channel; the control unit is used to perform the following steps: A floating current is applied to the motor based on a preset floating current curve; Obtain the target suspension position curve, which is the axial displacement curve of the impeller generated according to the target suspension current curve; The presence of a thrombus in the secondary flow channel of the ventricular assist device is determined based on the target suspension position curve and the preset suspension position curve. The preset suspension position curve is the axial displacement curve of the impeller generated according to the preset suspension current curve when there is no thrombus in the secondary flow channel of the ventricular assist device.

2. The control unit according to claim 1, characterized in that The waveform of the preset floating current curve is a sine wave or a square wave. The preset floating position curve reaches a first floating position at a first time and a second floating position at a second time. The first floating position is the maximum floating position in the preset floating position curve, and the second floating position is the minimum floating position in the preset floating position curve.

3. The control unit according to claim 2, characterized in that In determining whether a thrombus exists in the secondary flow path of the ventricular assist device based on the target suspension position curve and the preset suspension position curve, the control unit performs the following steps: A third suspension position and a fourth suspension position are determined from the target suspension position curve, wherein the third suspension position is the maximum suspension position in the target suspension position curve, and the fourth suspension position is the minimum suspension position in the target suspension position curve; Calculate a first difference and a second difference, where the first difference is the difference between the first floating position and the third floating position, and the second difference is the difference between the second floating position and the fourth floating position; The presence of a thrombus in the secondary flow channel of the ventricular assist device is determined based on the first difference and the second difference.

4. The control unit according to claim 3, characterized in that The waveform of the preset floating current curve is a sine wave. In determining whether a thrombus exists in the secondary flow channel of the ventricular assist device based on the first difference and the second difference, the control unit performs the following steps: Obtain the third time and the fourth time, wherein the third time is the time corresponding to the third floating position, and the fourth time is the time corresponding to the fourth floating position; If the first difference is greater than 0 and the third moment is earlier than the first moment, then it is determined that there is a thrombus in the secondary flow channel formed between the surface of the impeller away from the motor and the housing in the ventricular assist device. If the second difference is greater than 0 and the fourth moment is earlier than the second moment, then it is determined that there is a thrombus in the secondary flow channel formed between the impeller surface facing the motor and the housing in the ventricular assist device. Otherwise, there is no thrombus in the secondary flow channel of the ventricular assist device.

5. The control unit of claim 3, wherein, The waveform of the preset floating current curve is a square wave. In determining whether a thrombus exists in the secondary flow channel of the ventricular assist device based on the first difference and the second difference, the control unit performs the following steps: If the first difference is greater than 0, it is determined that there is a thrombus in the secondary flow channel formed between the surface of the impeller away from the motor and the housing in the ventricular assist device; If the second difference is greater than 0, it is determined that there is a thrombus in the secondary flow channel formed between the impeller surface facing the motor and the housing in the ventricular assist device; Otherwise, there is no thrombus in the secondary flow channel of the ventricular assist device.

6. The control unit of claim 3, wherein, The larger the first difference and / or the second difference, the larger the thrombus.

7. The control unit according to claim 4 or 5, characterized in that The motor includes a rotor and a stator, the stator including n winding units arranged evenly in a circle, where n is a multiple of 3; when a thrombus is present in the secondary flow channel of the ventricular assist device, the control unit is further configured to perform the following steps: At time i, the floating current applied to the i-th first winding unit is decreased, while the floating current applied to the i-th second winding unit is increased. The i-th first winding unit is any one of the n winding units, and the i-th second winding unit is the winding unit that is 180° away from the i-th first winding unit among the n winding units. i is a positive integer less than or equal to n. Obtain the first floating position, which is the minimum floating position of the n winding units at the i-th time. If the first floating position is greater than the preset floating position, it is determined that there is a thrombus at the secondary flow channel corresponding to the i-th first winding unit; Let i = i + 1, and repeat the above steps until i = n.

8. The control unit according to claim 7, characterized in that The control unit is also configured to perform the following steps: When a thrombus is present in the secondary flow channel corresponding to the i-th first winding unit, the floating current applied to the i-th first winding unit is increased, the floating current applied to the i-th second winding unit is decreased, and the rotation speed of the ventricular assist device is controlled to pulsate in order to flush out the thrombus.

9. A ventricular assist device, characterized by The ventricular assist device includes: case; An impeller is disposed within the housing, and a gap region exists between the impeller and the housing, the gap region forming a secondary flow channel; A motor that drives the impeller to rotate; A control unit that is communicatively connected to the motor, wherein the control unit is the control unit as described in any one of claims 1-8.

10. A medical device, characterized in that, It includes a processor, a memory, and a communication interface, wherein the memory stores one or more programs, and the one or more programs are executed by the processor, the one or more programs including instructions for performing the steps performed by the control unit as described in any one of claims 1-8.

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