A ventricular assist catheter pump

Abstract

The purpose of this invention is to provide a ventricular assist catheter pump with good bending performance and light weight. The motor is connected to the catheter at its proximal end and to the impeller at its distal end. The two ends of the rotor assembly's shaft are connected to the housing via proximal and distal bearings, respectively, forming a rotational support. A proximal PCB stator assembly and a distal PCB stator assembly with printed coils are respectively located on the proximal and distal sides of the magnet in the rotor assembly. These three components are arranged in parallel to form a double-air-gap axial magnetic circuit structure. This single-rotor-double-stator structure provides high output torque. This invention employs a flattened structure of the axial magnetic flux-coupled PCB stator, effectively shortening the axial length of the motor. The magnet diameter can be set larger, and the axial length is significantly reduced, allowing the blood pump to achieve an axial length of 15-20mm without changing the diameter, thus solving the problem of bending performance of blood pumps in clinical practice. The PCB stator assembly has a very thin structure, with the coils printed on it, which not only shortens the axial length of the motor but also reduces the overall weight of the motor.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a ventricular assist catheter pump. Background Technology

[0002] A catheter pump, a type of ventricular assist device, can be inserted percutaneously into the heart and can be configured to assist or replace the natural heart pumping function by pumping blood through circulation or continuous pumping, providing hemodynamic support for cardiogenic shock and acute heart failure. A catheter pump includes a catheter connecting to an external support device, a motor, an impeller, a cannula, a pigtail tube, a blood inlet, and a blood outlet. The motor, as the core component, is connected distally to the impeller and the blood cage, resulting in a relatively long continuous rigid section. Due to the tortuosity of blood vessels, a long continuous rigid section of the catheter pump is detrimental to its bending performance, and in severe cases, may pose a risk of vascular damage. Summary of the Invention

[0003] The purpose of this invention is to provide a ventricular assist catheter pump with good bending performance and light weight.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a ventricular assist catheter pump, including a motor, the proximal end of the motor being connected to the catheter and the distal end being connected to the impeller, characterized in that: the motor includes a housing, the two ends of the rotor assembly's shaft are respectively connected to the housing through a proximal bearing and a distal bearing to form a rotational support cooperation, and the proximal side and the distal side of the rotor assembly's magnet are respectively provided with a proximal PCB stator assembly and a distal PCB stator assembly with printed coils, the three being arranged in parallel and forming a double air gap axial magnetic circuit structure.

[0005] The near-end PCB stator assembly and the far-end PCB stator assembly have the same structure and are arranged symmetrically with respect to the magnet to balance the axial magnetic pull on the rotor assembly. The near-end PCB stator assembly is generally in the shape of a ring plate and is made of multiple layers of PCB boards stacked together. The coil is printed on one or both sides of the PCB board.

[0006] The near-end PCB stator assembly has 2-4 PCB layers, with a single PCB layer thickness of 0.1-0.2mm and an interlayer insulation layer thickness of ≥0.05mm.

[0007] The coils are configured as a three-phase, one-pole structure. On the same PCB board, the spacing between adjacent coils is ≥0.1mm, and the coil shapes are circular, square, trapezoidal, or polygonal.

[0008] The housing is made of metal, and the inner cavity of the housing is provided with an axial positioning structure. The near-end PCB stator assembly and the far-end PCB stator assembly are fixed to the housing through the axial positioning structure. The relationship between the outer diameter d of the magnet and the outer diameter D of the motor housing is: 0.7≤d / D≤0.9.

[0009] A shielding sheet is embedded in the housing between the near-end PCB stator assembly and the near-end bearing. The shielding sheet is made of ferritic alloy material and has a dense oxide layer formed by high-temperature oxidation treatment on its surface.

[0010] A wire channel is provided on the outer wall of the housing along its axial direction, and the distal end of the wire channel extends to a position corresponding to the electrical connection point of the distal PCB stator assembly.

[0011] The single-sided air gap between the end face of the magnet and the near-end PCB stator assembly is 0.08-0.15mm.

[0012] The inner lumen of the catheter is provided with a flushing fluid channel, through which the flushing fluid enters the inner lumen of the housing and flows out from the distal end of the housing.

[0013] The surfaces of the near-end PCB stator assembly and the far-end PCB stator assembly are covered with an insulating encapsulation layer configured to isolate the coils from the environment within the housing.

[0014] In the above-described solution, this single-rotor-dual-stator structure provides high output torque. This invention employs a flattened structure with axial magnetic flux and a PCB stator, effectively shortening the motor's axial length. This allows for a larger magnet diameter and a significantly reduced axial length, enabling the blood pump to achieve an axial length of 15-20mm without changing the diameter, thus solving the problem of poor bending performance in clinical applications. The PCB stator assembly is very thin, with the coils printed on it, which not only shortens the motor's axial length but also reduces the overall weight of the motor. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the duct pump; Figure 2 This is a partial structural diagram of a duct pump; Figure 3 for Figure 2 A sectional view; Figure 4 A 3D view of the near-end / far-end PCB stator assembly; Figure 5 This is a diagram showing the magnetic field distribution. Detailed Implementation

[0016] To facilitate understanding, let's first define the orientation: "proximal" or "proximal" refers to the side closer to the operator / doctor, while "distal" or "distal" refers to the side farther from the operator / doctor, i.e., the side closer to the heart. Below, we'll combine these definitions... Figures 1-5 The present invention will be described in further detail below.

[0017] like Figure 2 , Figure 3 As shown, a ventricular assist catheter pump includes a motor 10, with its proximal end connected to a catheter 20 and its distal end connected to an impeller 30. The motor 10 includes a housing 11. The two ends of the rotor assembly 12's shaft 121 are respectively connected to the housing 11 via proximal bearings 13 and distal bearings 14 to form a rotational support. The rotor assembly 12's magnet 122 has a proximal PCB stator assembly 15 and a distal PCB stator assembly 16, each printed with coil a, on its proximal and distal sides, respectively. These three PCB stators are arranged in parallel to form a double-air-gap axial magnetic circuit structure. The rotor magnet 122 is sandwiched between the two PCB stators. When a three-phase alternating current with a phase difference of 120° is applied to the coil a on the PCB stator, a rotating magnetic field is generated, driving the magnet 122 to rotate, thereby driving the impeller 30. Magnetic lines of force pass sequentially through the proximal air gap, the magnet 122, and the distal air gap along a direction parallel to the shaft 121, forming a double-air-gap axial magnetic circuit structure. This single-rotor-dual-stator structure is equivalent to a dual-motor structure, resulting in high output torque. This invention employs a flattened structure with axial magnetic flux and a PCB stator, effectively shortening the axial length of the motor 10. Because of the space saved in the stator along the axial direction, the diameter of the magnet 122 in the rotor assembly 12 can be set larger, significantly reducing the axial length of the magnet 122. This allows the blood pump to achieve an axial length of 15-20mm while maintaining a constant diameter (≤6mm), solving the problem of poor bending performance of blood pumps in clinical practice. The PCB stator assembly has a very thin structure, with coil a printed on it, which not only ensures the axial length of the motor 10 but also reduces the overall weight of the motor 10.

[0018] In a single-stator drive structure, the rotor is subjected to a unidirectional magnetic pull that causes it to move towards the stator. This force significantly increases the load on the bearings, leading to increased wear, reduced efficiency, and potential vibration. To prevent this problem, the near-end PCB stator assembly 15 and the far-end PCB stator assembly 16 have identical structures and are symmetrically arranged relative to the magnet 122. The axial magnetic pulls generated by the two stators on the rotor are equal in magnitude and opposite in direction, canceling each other out. This balances the axial magnetic pull on the rotor assembly 12, significantly reducing axial compounding and improving the mechanical performance, operational smoothness, and service life of the motor 10. To achieve a sufficient number of coil turns to generate the required electromagnetic torque without increasing the radial dimension of the motor, the near-end PCB stator assembly 15 is generally annular and composed of multiple stacked PCBs. The coil a is printed on one or both sides of the PCB. This greatly improves space utilization and torque density within a limited planar area, which is beneficial for further compression of the motor's axial dimension.

[0019] Preferred options, please refer to Figure 4The PCB board of the near-end PCB stator assembly 15 has 2-4 layers to reduce bending fatigue; the thickness of a single PCB board is 0.1-0.2mm, and the thickness of the interlayer insulation layer is ≥0.05mm to ensure that the withstand voltage performance is ≥2 times the rated voltage of the motor.

[0020] The coil a is configured as a three-phase, one-pole structure. To ensure electrical safety and signal integrity, the spacing between adjacent coils on the same PCB board is ≥0.1mm to reduce mutual inductance interference. The coil shape is circular, square, trapezoidal, or polygonal, with trapezoidal being preferred to maximize electromagnetic arrangement.

[0021] To ensure the strength of the motor 10, the housing 11 is made of metal. Metal, as a highly efficient heat conductor, can quickly dissipate the heat generated by the PCB stator and bearings during operation, and dissipate it through flowing blood or flushing fluid. The inner cavity of the housing 11 is equipped with an axial positioning structure. The near-end PCB stator assembly 15 and the far-end PCB stator assembly 16 are fixed to the housing 11 by this axial positioning structure. The relationship between the outer diameter d of the magnet 122 and the outer diameter D of the motor housing is: 0.7 ≤ d / D ≤ 0.9. Through multiple tests, this ratio range has been shown to achieve the optimal balance between torque output, structural strength, and manufacturing feasibility.

[0022] Because of the high-frequency alternating magnetic field present in the axial direction and its proximity to the bearing, the service life of the near-end bearing 13 will be reduced. To address this issue, a shielding plate 17 is embedded within the housing 11 between the near-end PCB stator assembly 15 and the near-end bearing 13. This effectively shields the magnetic field and extends the bearing's service life. The shielding plate 17 is made of ferritic alloy material with a dense oxide layer formed through high-temperature oxidation treatment. It exhibits good biocompatibility and magnetic permeability, and after high-temperature treatment, it possesses high corrosion resistance, allowing direct contact with blood.

[0023] Furthermore, a wire channel 111 is provided on the outer wall of the housing 11 along its axial direction, and the distal end of the wire channel 111 extends to a position corresponding to the electrical connection point of the distal PCB stator assembly 16.

[0024] The single-sided air gap between the end face of the magnet 122 and the near-end PCB stator assembly 15 is 0.08-0.15mm to improve the magnetic field utilization rate.

[0025] To prevent blood from entering the motor 10, flushing fluid is introduced into the inner cavity of the motor 10. The flushing fluid flows out from the distal bearing 14, effectively preventing blood from entering. A flushing fluid channel 21 is provided in the inner cavity of the conduit 20. The flushing fluid enters the inner cavity of the housing 11 through the flushing fluid channel 21 and flows out from the distal end of the housing 11. While flowing, the flushing fluid can remove the heat generated by the motor 10 during operation, ensuring the stability and safety of the motor 10 during operation. Furthermore, it has unique advantages in heat dissipation: 1. Significantly improved heat dissipation efficiency: The absence of an iron core reduces hysteresis / eddy current losses (traditional iron cores are the main source of loss), reducing the total heat generated by the motor 10 by 30%-50%. Simultaneously, the PCB board itself is an insulating and thermally conductive material, and the coil a is directly attached to the PCB board, allowing heat to be quickly conducted to the housing 11 or the heat dissipation structure through the PCB board, avoiding localized heat accumulation. 2. Better heat dissipation uniformity: The coil a is evenly distributed on the PCB board through photolithography, dispersing the heat points and eliminating the "localized hot spot concentration" problem caused by the iron core, resulting in smaller operating temperature fluctuations (typically controlled within ±5℃).

[0026] Furthermore, the surfaces of the near-end PCB stator assembly 15 and the far-end PCB stator assembly 16 are covered with an insulating encapsulation layer, which is configured to isolate the coil from the environment within the housing 11. A medical-grade coating such as parylene can be used to form a thin film, exhibiting excellent biocompatibility and insulation; alternatively, medical-grade silicone or epoxy resin can be used for potting.

[0027] The main advantages of the catheter pump in this invention are its ultra-miniaturization, light weight, and short axial rigid section length, making it more suitable for femoral and axillary artery interventions in clinical practice, especially for patients with arteriosclerosis, arterial malformations, and arterial stenosis. It also offers advantages in performance control: 1. The coil is printed using laser direct imaging (LDI) technology, with a linewidth tolerance ≤ ±0.01mm and coil spacing deviation ≤ 0.005mm, ensuring symmetrical distribution of the three-phase coils (phase difference error ≤ 5°), and improving magnetic field uniformity by 35% compared to traditional machine-wound motors. Repeatability accuracy can reach ±0.001mm. 2. The PCB coil uses flat copper foil conductors, resulting in more uniform current distribution and reducing copper loss by 30%-50% compared to traditional enameled wire windings (at the same power). The power consumption of the implantable medical motor can be controlled within 50mW, extending battery life. 3. The inductance value of the PCB coil can be precisely adjusted through the number of turns and linewidth (≤10μH), with a start-up response time ≤10ms, more than 50% shorter than traditional motors. With the help of PWM high-frequency drive (frequency ≥20kHz), millisecond-level speed switching and positioning adjustment can be achieved.

[0028] Figure 5The diagram shows the magnetic field distribution. As can be seen, two ring-shaped PCB coils are symmetrically attached to both sides of the rotor magnet. Each winding is fed in opposite phases, instantly establishing a confrontational magnetomotive force between the NN and SS windings. Magnetic lines originate from the upper PCB, penetrate the insulating medium perpendicularly, converge axially along the thickness of the permanent magnet, pass through a high-remanence neodymium iron boron magnetic ring, and then fold back to the lower PCB, forming a closed magnetic flux loop. Alternating current causes the magnetic flux direction to periodically reverse with frequency, generating a stable rotating magnetic field within the axial gap. This drives the conductive ring or copper foil coil to produce a Lorentz force, propelling the rotor to rotate continuously. The short magnetic circuit and low magnetic leakage significantly improve torque density and efficiency, enabling a thin, lightweight, and high-power axial flux drive solution.

[0029] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A ventricular assist catheter pump, comprising a motor (10), wherein the proximal end of the motor (10) is connected to a catheter (20) and the distal end is connected to an impeller (30), characterized in that: The motor (10) includes a housing (11). The two ends of the shaft (121) of the rotor assembly (12) are connected to the housing (11) through a near-end bearing (13) and a far-end bearing (14) respectively to form a rotational support. The magnet (122) of the rotor assembly (12) is provided with a near-end PCB stator assembly (15) and a far-end PCB stator assembly (16) with coils (a) printed on it. The three are arranged in parallel and form a double air gap axial magnetic circuit structure.

2. The ventricular assist catheter pump according to claim 1, characterized in that: The near-end PCB stator assembly (15) and the far-end PCB stator assembly (16) have the same structure and are arranged symmetrically with respect to the magnet (122) to balance the axial magnetic pull force on the rotor assembly (12). The near-end PCB stator assembly (15) is in the shape of an annular plate and is made of multiple layers of PCB boards stacked together. The coil (a) is printed on one or both sides of the PCB board.

3. The ventricular assist catheter pump according to claim 2, characterized in that: The PCB board of the near-end PCB stator assembly (15) has 2-4 layers, with a single layer PCB board thickness of 0.1-0.2mm and an interlayer insulation layer thickness of ≥0.05mm.

4. The ventricular assist catheter pump according to claim 2, characterized in that: The coil (a) is configured as a three-phase one-pole structure. On the same PCB board, the spacing between adjacent coils is ≥0.1mm, and the coil shape is circular, square, trapezoidal, or polygonal.

5. The ventricular assist catheter pump according to claim 1, characterized in that: The housing (11) is made of metal. The inner cavity of the housing (11) is provided with an axial positioning structure. The near-end PCB stator assembly (15) and the far-end PCB stator assembly (16) are fixed to the housing (11) by the axial positioning structure. The relationship between the outer diameter d of the magnet (122) and the outer diameter D of the motor housing is: 0.7≤d / D≤0.

9.

6. The ventricular assist catheter pump according to claim 2, characterized in that: A shielding plate (17) is embedded in the housing (11) between the near-end PCB stator assembly (15) and the near-end bearing (13). The shielding plate (17) is made of ferritic alloy material and has a dense oxide layer formed by high-temperature oxidation treatment on its surface.

7. The ventricular assist catheter pump according to claim 2, characterized in that: A wire channel (111) is provided on the outer wall of the housing (11) along its axial direction, and the far end of the wire channel (111) extends to a position corresponding to the electrical connection point of the far end PCB stator assembly (16).

8. The ventricular assist catheter pump according to claim 2 or 4, characterized in that: The single-sided air gap between the end face of the magnet (122) and the near-end PCB stator assembly (15) is 0.08-0.15 mm.

9. The ventricular assist catheter pump according to claim 1, characterized in that: The inner cavity of the conduit (20) is provided with a flushing fluid channel (21), and the flushing fluid enters the inner cavity of the housing (11) through the flushing fluid channel (21) and flows out from the distal end of the housing (11).

10. The ventricular assist catheter pump according to claim 1 or 9, characterized in that: The surfaces of the near-end PCB stator assembly (15) and the far-end PCB stator assembly (16) are covered with an insulating encapsulation layer configured to isolate the coil from the environment within the housing (11).

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