CN201437016U - implantable ventricular assist device - Google Patents

Abstract

The utility model belongs to the technical field of medical apparatuses, in particular to an implanted ventricular assist device, which mainly comprises an implanted miniature axial-flow blood pump, an implanted real-time flow detector and a data processing and display system. The miniature blood pump consists of a brushless motor and an axial-flow blood pump, the axial-flow blood pump adopts an impeller-shaft-integrated tandem rotor structure, the design of the flow passage and rotor blades of the axial-flow blood pump is optimized, and moreover, the pump and the motor are integrated; and a miniature Doppler probe, which comprises a wafer, a master oscillator, an emission amplifier, a receiving amplifier, a demodulator and the like, is adopted as the real-time flow detector. The utility model has the advantages of small size, light weight, steady operation, no thrombosis and real-time and accurate detection.

Description

implantable ventricular assist device

technical field

The utility model belongs to the technical field of medical devices, in particular to a ventricular assisting device, in particular to an implantable ventricular assisting device.

Background technique

Heart failure is the most common diagnosis of cardiovascular discharged patients, and it is also the disease with the highest medical expenses. Heart failure has been regarded as an important issue to be solved in this century in the world. Due to the shortage of donors, about 30% of the patients who were ready to receive and heart transplantation died of cardiac function deterioration while waiting for the donor heart. The emergence and development of ventricular assist device (VAD) has brought a new approach to the treatment of heart failure. Since 1981, the National Institutes of Technology (NIH) has launched the RFDs program (a Request For proposals) for the development of "implantable ventricular assist devices that enable patients to move freely for long-term cardiac support." A total of $40 billion has been invested so far to support the development of ventricular assist devices. The 2006 European heart failure guidelines have included ventricular assist devices as one of the methods of heart failure treatment. After years of research, several products have been used clinically in the world, mainly for the transition of heart transplantation, recovery of heart function and even permanent replacement therapy. But these products are expensive, and all have certain deficiencies.

Contents of the invention

The purpose of the utility model is to provide an implantable ventricular assist device which can be applied to the treatment of the end stage of heart failure.

Since this ventricular assist device is to be implanted in the body, the weight and size of its main components, including a micro-axial blood pump and a real-time flow test probe, are severely restricted. For this reason, the utility model has carried out improved design to these main parts, in order to realize the structure miniaturization of the device, function synthesis.

The implantable ventricle assisting device designed by the utility model comprises two parts: an implanted miniature axial flow blood pump integrated with a pump and an implanted real-time flow detector.

1. The pump-in-one implantable axial flow blood pump designed by the utility model is designed as follows:

1. New blood channel design

In the general ventricular assist device pump system (DeBakey VAD, Berlin Heart Incor I and domestic VZ-II A type), the motor magnet rotor and the blood pump rotor are placed in the blood flow channel, so that there is an extra rotor magnet in the blood flow channel , the area of the blood flow channel is reduced, which affects the blood flow, and the air gap between the motor stator and the rotor is also increased, and the required power is also increased.

The flow path of the utility model is characterized in that the blood is driven by a micro-blood pump rotor-axis integrated tandem rotor 9 placed in the inner hole of the motor rotor cylindrical magnetic steel 5, forming a main channel of φ10-11mm and a gap of φ0.2- 0.25mm tributary channel. There is no motor magnetic steel rotor in the main flow channel, the flow channel obstruction is small, and the flow channel area is large, which can ensure that a large blood flow passes through the main flow channel, that is, through the inner hole of the rotor cylindrical magnetic steel 5, and the diameter of the inner hole of the rotor cylindrical magnetic steel 5 It is 10-11mm; there is no obstacle in the branch channel to hinder the flow of blood, and because the gap between the branch channel is small, the air gap between the stator coil 3 of the brushless motor and the rotor cylindrical magnet 5 is also very small, thereby significantly reducing the brushless The size and weight of the DC motor unit and the axial flow blood pump are suitable for implantable heart assist devices. (figure 1)

2. Design of rotor blades;

In view of the long and narrow flow path of the axial blood pump combined with the pump mechanism, the diameter of the blades of the rotor is limited, and the flow path is divided into a main flow path and a branch flow path. The utility model adopts the tandem propeller concept in the marine propeller special propeller, and designs the rotor of the axial flow blood pump in the form of a tandem rotor. The so-called tandem rotor means that two different rotors are installed on the same shaft and rotate at the same speed. This type of tandem rotor is especially suitable for implantable axial blood pumps with narrow and long flow channels and limited rotor diameters. Specifically, the tandem rotor 9 in the present invention consists of a front small rotor 8 and a rear large rotor 10 coaxially fixed, as shown in FIG. 2 . The front small rotor 8 is in the front, the diameter is 10-11mm, the axial length is 21-22mm, the pitch is 35-37mm, the rear large rotor is 10, the diameter is 18-19mm, the axial length is 10-11mm, Pitch is 27-28mm, is fixed on the same axle 17, and the diameter of axle is 4-5mm.

Since the flow channel of the implanted axial flow blood pump of the utility model is divided into a main flow channel and a branch flow channel, and the size of the main flow channel and the branch flow channel is very different, the front small rotor is in the front, and the rear large rotor is in the back. , which can ensure that the blood is firstly affected by the rotating blades of the small rotor when entering the flow channel, and ensure that most of the blood passes through the main channel when entering the flow channel, while a small amount of blood passes through the blade tip of the large trochanter arranged behind The effect is passed, which can ensure that the blood bifurcates smoothly in the main and tributary channels, passes through smoothly, and does not produce congestion and thrombus.

In order to further improve the efficiency of the implanted axial flow blood pump and increase the pressure head, the cutting surface of the large and small tandem rotor blades of the utility model adopts the airfoil-shaped blade cutting surface form of a marine duct propeller (see Figure 3), replacing the general pump in the form of a flat leaf cutaway. Compared with the flat leaf cut surface, when the blood flows through the wing shaped leaf cut surface, positive pressure 22 occurs on the leaf cut surface leaf surface 20, and negative pressure 23 occurs on the leaf cut surface leaf back 21, and the leaf surface, leaf back The pressure difference can improve the blood pump efficiency and increase the pressure head.

3. Design of motor stator

Ventricular assist devices not only require small size and light weight, but also require balanced operation, low vibration, and low noise to improve comfort during use. As shown in Figure 4, the stator of the brushless motor body of the implantable axial flow blood pump of the utility model adopts a two-phase conduction, three-phase six-state conductive model, which not only improves the utilization rate of the winding , the size and weight are reduced, and the magnetic state angle is reduced, which reduces the essential rotation fluctuation caused by the commutation of the brushless motor; the stator winding adopts the hollow cup winding, which not only solves the difficulty of the small-sized stator off-line problem, and the stator core no longer has cogging, which completely eliminates the essential rotation fluctuation caused by the tooth harmonic magnetic field.

The brushless motor rotor adopts Nd-steel-boron permanent magnet material with high residual magnetic induction intensity, and adopts radially magnetized, one-pole cylindrical magnetic steel, so that it can be used under the large electromagnetic air gap of the hollow cup winding. It can still generate a strong air gap magnetic field, which reduces the volume and weight of the motor. The overall cylindrical magnetic steel with one pair of poles is easier to ensure uniform quality, and reduces the dynamic unbalance under high-speed motion, and because there is no unilateral Magnetic pull, so the operation is stable and the comfort of use is improved.

Considering that the special pump combined with an implantable axial flow blood pump is used for implantable ventricular assist devices, it has high requirements on the sealing of the structure. If a conventional brushless DC motor position sensor is used, the stator of the sensor will There are too many Hall elements (at least 5 wires), which will lead to the sealing of the lead wires and the rejection of the lead material and the human body. The utility model uses a circuit to realize the functions of identifying the rotor position and self-starting, and plays the role of a position sensor. The necessary position sensor of the conventional brushless constant current motor is canceled, which not only reduces the difficulty of sealing, improves the reliability, but also simplifies the structure and reduces the volume.

According to the above design, the specific structure of the pump-in-one implantable axial flow blood pump of the present invention is shown in FIG. 1 . It is composed of casing 1, stator core 2, stator coil 3, motor bracket 4, rotor cylindrical magnetic steel 5, paddle shaft integrated tandem rotor 9, left-handed outlet stator 13 and right-handed inlet stator 15; among them, the paddle shaft The integrated tandem rotor 9 is composed of a front small rotor 8 and a rear large rotor 10 coaxially fixed. Inside the casing 1 are the stator core 2 and the rotor coil 3 in sequence; the paddle shaft integrated tandem rotor 9 passes through the rotor cylindrical magnet The center hole of steel 5, the two ends of axle are respectively fixed in left-handed outlet stator 13 and right-handed inlet stator 15 by ceramic bearing 14, left-handed outlet stator 13, right-handed inlet stator 15 are respectively fixed with motor support 4 two ends. The rotor cylindrical magnetic steel 5 is arranged in the middle part of the stator coil 3, corresponding to the position of the front small rotor 8 of the tandem rotor 9, and is fixed with the front small rotor 8; the tandem rotor 9 and the inner wall of the stator coil 3 The main channels 11 and 12 of the blood are formed with the inner wall of the central hole of the rotor cylindrical magnetic steel 5, and the tributary channels 6 and 7 of blood are formed between the outer wall of the rotor cylindrical magnetic steel 5 and the inner wall of the stator coil 3.

2. The implanted real-time flow detector in the utility model adopts the principle of ultrasonic Doppler and uses exquisite technology to make an inner diameter of 10mm to 11mm, an outer diameter of 25mm to 26mm, and a length of 25mm to 26mm , The 5MHz ultrasonic Doppler speed measuring probe with a weight of only 15g~16g can be placed at the outlet flow channel of the miniature axial flow blood pump and implanted in the body as a whole with the miniature axial flow blood pump, so that it can be detected in real time and correctly There are fine particles (blood cells) in the pipeline (blood flow rate), which indirectly measures the blood flow in the pipeline.

The real-time flow detector also includes a data processing system and a display system. The data processing system converts the ultrasonic Doppler frequency shift signal measured by the probe into a blood flow velocity signal by using f-v conversion and A/D data conversion. The specific structure is shown in Figure 5, which includes ultrasonic Doppler speed measuring probe, data processing system and display system. Described velocity measuring probe is made up of probe inner shell 30 and probe outer cover 31; Places between probe inner shell 30 and probe outer shell 31 and is connected successively by wafer 33, main vibrator 36, transmitting amplifier 37, receiving amplifier 38 and demodulator 39 The circuit that forms; Wherein, chip 33 is placed with the angle of 120 °-140 ° according to ultrasonic Doppler information transmission requirement, main vibrator 36 adopts 5MHZ continuous sinusoidal oscillation circuit, through transmitting amplifier 37 and transmitting transducer (chip 33) Generate an ultrasonic beam 34; when the ultrasonic beam 34 is launched to the moving target---the blood particle 35, reflection occurs to obtain an echo signal 34, and the echo signal 34 enters the receiving amplifier after receiving the transducer (chip 33) 38 to amplify; and then through the demodulator 39 to give dewave, extract the Doppler frequency shift signal, input the data processing system 40 for further data processing, and finally display on the display system 41.

The calculation and display system of the real-time flow detector uses a stable industrial computer motherboard CPU memory, soft hard disk drive, and external standard equipment such as a display. The computer is equipped with special detection and calculation software for flow calculation and filtering, so that the real-time speed and flow rate of the ventricular assist device detected by the real-time flow detector can be displayed on the screen of the monitor and recorded in the memory of the industrial computer.

Description of drawings

Fig. 1 is a structural illustration (sectional view) of the present utility model.

Fig. 2 is a structural diagram of the tandem rotor integrated with paddle shafts of the present invention.

Fig. 3 is a blade section and force diagram of the tandem rotor integrated with paddle shafts of the present invention.

Figure 4 Schematic diagram of brushless motor circuit structure

Fig. 5 is a schematic structural diagram of an implantable real-time flow monitor.

Labels in the figure: 1. Shell, 2. Stator core, 3. Stator coil, 4. Motor bracket, 5. Rotor cylindrical magnet, 6, 7. Branch channel, 8. Front small rotor, 9. Integrated propeller shaft tandem rotor, 10. rear large rotor, 11, 12. main channel, 13. left-handed outlet stator, 14. ceramic bearing, 15. right-handed inlet stator, 16. blood flow direction, 17. rotor shaft, 20. The blade surface of the blade cut surface of the rotor blade, 21. the blade back of the rotor blade blade cut surface, 22. the pressure distribution line of the blade surface, and 23. the pressure distribution line of the blade back. 24. Stator core, 25. Stator B-Y coil, 26. Stator A-X coil, 27. Stator C-Z coil, 28. Cylindrical magnetic steel, 29. Blood flow direction, 30. Probe inner shell, 31. Probe cover, 32. Blood , 33. Chip, 34. Ultrasonic beam and echo, 35. Blood particles, 36. Main oscillator, 37. Transmitting amplifier, 38. Receiving amplifier, 39. Demodulator, 40. Data processing system, 41. Display system

Detailed ways

As shown in accompanying drawing 1, the pump mechanism integrated axial flow blood pump is composed of brushless motor and axial flow blood pump. The brushless motor is composed of the stator core 2, the stator coil 3 and the rotor cylindrical magnetic steel 5 fixed on the casing 1 and the motor bracket 4; the axial flow blood pump is composed of a tandem rotor 9 integrated with a paddle shaft through a ceramic bearing 14 and a left-handed outlet. Stator 13 is connected with right-handed inlet stator 15 . The motor rotor cylindrical magnetic steel 5 is fixedly connected with the front tandem small rotor 8; the left-handed outlet stator 13 and the right-handed inlet stator 15 are connected with the motor bracket 4, thereby becoming a pump mechanism integrated axial flow blood pump. When the stator coil 3 of the motor is energized, a rotating magnetic field is generated in the air gap between the inner circle of the stator coil 3 and the outer circle of the rotor cylindrical magnet 5 to drive the rotor cylindrical magnet 5 to rotate, and drive the rotor cylindrical magnet 5 to rotate. The paddle-shaft integrated tandem rotors 9 connected together rotate together, and the blood is sucked in from the inlet of the pump body and flows out from the outlet. Since the tandem rotor 9 of the axial flow blood pump is composed of the front small rotor 8 and the rear tandem large rotor 10, the blood entering the pump body is first affected by the front small rotor 8, and most of it passes through the main channels 11 and 12. , and a small amount of blood passes through the branch channels 6 and 7 by means of the blade tip of the rear large rotor 10 arranged at the back, so that the blood flow entering the pump body can be guaranteed to bifurcate smoothly when entering the main and branch channels. Through, there is no phenomenon of blood congestion and thrombus.

The utility model designs and manufactures an implantable axial-flow blood pump with a pump in one, the size of which is φ29.6mm×72mm, and the weight is 158g. Among them, the size of the axial flow pump is φ18.5mm×72mm, the front small rotor 8 is φ10mm×21mm, the rear large rotor 10 is φ18mm×10mm, the inner diameter of the rotor cylindrical magnetic steel 5 is φ10mm, the outer diameter is φ17.6mm, and the length is 21mm, so the main channel φ10mm, branch channel gap 0.25mm. This example has been successfully applied to animal experiments implanted in calf thorax. When the pump speed is 9000 rpm, the blood flow can reach 5 liters/min, which is completely suitable for the application of implantable ventricular assist devices.

The structure of the brushless motor is shown in Figure 4. The stator adopts a two-phase conduction, three-phase six-state conduction mode, and the stator coil 3 in the stator core 24 is divided into three parts: B-Y coil 25, A-X coil 26, and C-Z coil 27. The stator winding adopts the hollow cup winding form, and the rotor cylindrical magnetic steel 28 adopts neodymium steel boron permanent magnet material, which is magnetized by radial direction.

As shown in Figure 5, the real-time flow detector mainly consists of three parts: an ultrasonic Doppler velocity measuring probe, a data processing system and a calculation display system. Among them, the ultrasonic Doppler velocity measuring probe is integrated with the flow channel of the pump-in-one implantable axial blood pump and implanted in the body, so the test probe requires strong function, small size and light weight. For this reason, the present invention utilizes delicate processing technology and specific gravity light and good titanium alloy material of blood compatibility to design and process the ultrasonic Doppler speed measuring probe, and this speed measuring probe is made of a length of 25-26mm and an internal diameter of 10-11mm. The probe inner shell 30 is composed of a probe outer cover 31 with an outer diameter of 25-26mm. A chip 33 , a main oscillator 36 , a transmitting amplifier 37 , a receiving amplifier 38 , and a demodulator 39 are sequentially placed between the probe inner shell 30 and the outer cover 31 . The wafer 33 is placed at an angle of 120-140° as required for ultrasound Doppler information transmission. This ultrasonic probe is a continuous ultrasonic Doppler probe, which calculates the moving speed of the moving point by continuously transmitting the ultrasonic signal at the static (fixed) point and detecting the Doppler frequency shift frequency generated by the ultrasonic signal emitted from the moving point . The main vibrator 36 is a 5MHz continuous sinusoidal oscillator circuit, which generates the same frequency signal as the resonant frequency of the transmitting transducer through the transmitting amplifier 37, to excite the transmitting transducer (chip 33) to generate the ultrasonic beam 34, when the ultrasonic beam is launched to the moving target ——When the blood particles 35, the moving target just has the reflected echo signal 34, after receiving the echo signal 34 through the receiving transducer (chip 33), it is amplified by the low-noise receiving amplifier 38, and then through the demodulator 39 to dewave and extract the Doppler frequency shift signal, and then pass through the low-pass filter to filter out the pure Doppler frequency shift signal and amplify it and input it to the data processing system 40 for further processing. The data processing system converts the Doppler signal into a speed signal through f-v conversion (frequency-speed conversion), and then converts the analog speed signal into a digital speed signal through A/D conversion (analog/digital conversion), and inputs it to The calculation and display system calculates the flow rate from the digital speed signal through special calculation software and displays it on the display.

In this embodiment, the probe shell is made of titanium alloy with light specific gravity and better blood compatibility. The inner shell of the probe shell is φ10mm, the outer shell is φ25mm, the length is 25mm, and the weight is only 16g. The flow channel of the implantable axial flow blood pump integrated with the pump mechanism can be integrated into the body. An implantable ventricular assist device has been combined with a pump-in-one implantable axial blood pump, and has been successfully applied to animal experiments implanted in calves.

Claims (3)

1. An implantable ventricular assist device is composed of an implantable miniature axial flow blood pump and an implantable real-time flow detector, characterized in that: The pump-in-one implantable micro axial flow blood pump includes two parts: a brushless motor and a micro blood pump, and is characterized in that it consists of a casing (1), a stator core (2), a stator coil (3), Motor bracket (4), rotor cylindrical magnetic steel (5), paddle shaft integrated tandem rotor (9), left-handed outlet stator (13) and right-handed inlet stator (15), wherein the paddle shaft is integrated in tandem The rotor (9) is composed of a front small rotor (8) and a rear large rotor (10) coaxially fixed, inside the shell (1) are the stator core (2) and the rotor coil (3); The column rotor (9) passes through the central hole of the rotor cylindrical magnetic steel (5), and the two ends of the shaft are respectively fixed in the left-handed outlet stator (13) and the right-handed inlet stator (15) by ceramic bearings (14), and the left-handed outlet The stator (13) and the right-handed inlet stator (15) are respectively fixed to the two ends of the motor bracket (4); the rotor cylindrical magnetic steel (5) is arranged in the middle part of the stator coil (3), corresponding to the tandem rotor (9) The position of the front small rotor (8) is fixed together with the front small rotor (8); the inner wall of the tandem rotor (9) and the stator coil (3) and the inner wall of the central hole of the rotor cylindrical magnetic steel (5) The blood flow channels (6, 7) are formed between the outer wall of the rotor cylindrical magnetic steel (5) and the inner wall of the stator coil (3) forming the main flow channel (11, 12) of blood; The implantable real-time flow detector includes three parts: an ultrasonic Doppler velocity measuring probe, a data processing system and a display system; the ultrasonic Doppler velocity measuring probe has an inner diameter of 10 mm to 11 mm and an outer diameter of 25 mm to 26mm probe inner shell (30) and a probe outer cover (31) with a length of 25mm to 26mm; between the probe inner shell (30) and the probe outer shell (31) is placed a chip (33), a main vibrator (36) , transmitting amplifier (37), receiving amplifier (38) and demodulator (39) are connected successively to form the circuit; Wherein, chip (33) is placed with the angle of 120 °-140 ° according to ultrasonic Doppler information transmission requirement, main Vibrator (36) adopts 5MHZ continuous sinusoidal oscillation circuit to generate ultrasonic beam (34) by transmitting amplifier (37) and chip (33); , reflection occurs, and an echo signal (34) is obtained. The echo signal (34) enters the receiving amplifier (38) to amplify through the chip (33), and then through the demodulator (39), dewaves and extracts The Doppler frequency shift signal is input to the data processing system (40) for further data processing, and finally displayed on the display system (41); It is integrated with the miniature axial flow blood pump and implanted in the body. 2. The implantable ventricular assist device according to claim 1, characterized in that the blade section of the tandem rotor (9) with integrated paddle shaft adopts an airfoil shape. 3. The implantable ventricular assist device according to claim 1, characterized in that the stator of the brushless DC motor body adopts a conduction mode of two-phase conduction and three-phase six-state, and the stator coil (3) adopts a hollow cup winding, The rotor cylindrical magnetic steel (5) adopts NdFeB permanent magnet material.

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