Right core impeller and right core auxiliary device thereof

Abstract

The right center impeller is stable in flow field, good in cavitation performance and small in shearing force, the right center impeller comprises a hub and blades, the hub comprises a hub body and a hub tail, the blades are suitable for being driven by the hub to rotate, and blood is conveyed to the far end of the impeller from the near end of the impeller; the hub body is of a frustum structure with the radius gradually increasing from the near end to the far end, and the hub tail is of a frustum structure with the radius gradually decreasing from the near end to the far end. The frustum-shaped hub tail part has certain flow guide and rectification effects, so that the flow velocity is reduced when blood passes through, and the pressure in a flow field is reduced; the cone is gentle and reasonable in transition, so that the blood is powerfully supported when flowing through the surface of the model, flow separation and flow separation are not easy to occur, and a flow field is smoother; the shear force in a reasonable flow field is smaller, and the hemolytic property is further improved. The impeller has the hydraulic performance and the hemolytic performance of the blood pump at the same time, and in addition, due to improvement of the cavitation performance, the impeller rotates more stably, noise is low, and the impeller is more friendly to patients.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a right heart impeller and a right heart assist device thereof. Background Art

[0002] The ventricular assist device can be introduced into the heart percutaneously and can be constructed to assist or replace the natural heart pump function through the circulation pumping or continuous pumping of blood, providing hemodynamic support for cardiogenic shock and acute heart failure. When the ventricular assist device is deployed on the left side of the heart, the ventricular assist device pumps blood from the left ventricle of the heart into the aorta; when the ventricular assist device is deployed on the right side of the heart, the ventricular assist device pumps blood from the inferior vena cava / jugular vein, bypasses the right atrium and right ventricle, and pumps blood into the pulmonary artery. Taking the right ventricular assist device as an example, its structure includes a catheter, a motor, a blood inflow cage, a spring tube, and a blood outflow cage, which are arranged in sequence from the proximal end to the distal end. The blood inflow cage, the spring tube, and the blood outflow cage together constitute a blood flow channel, the blood inflow cage is located in the inferior vena cava / jugular vein, the blood outflow cage is located at the pulmonary artery, and the blood enters the spring tube from the blood inflow cage and is ejected from the blood outflow cage. The blood flow power of the ventricular assist device comes from the high-speed rotation of the impeller. The structural design of the impeller has an important influence on the hydraulic performance, hemolytic performance and stability of the ventricular assist device. Summary of the invention

[0003] An object of the present invention is to provide a right-heart impeller with a stable flow field, good cavitation performance and small shear force.

[0004] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a right-heart impeller, the impeller comprising a hub and at least one blade fixed to the outer periphery of the hub; The hub comprises a hub body and a hub tail connected in sequence from the proximal end to the distal end, and the blades are adapted to rotate under the drive of the hub to transport blood from the proximal end of the impeller to the distal end of the impeller; The hub body is a frustum structure with a radius gradually increasing from the proximal end to the distal end, the hub tail is a frustum structure with a radius gradually decreasing from the proximal end to the distal end, and the axial length of the hub tail is smaller than the axial length of the hub body.

[0005] Furthermore, the angle between the surface of the rear portion of the hub and the axis is α, and the value of α is 25° to 35°.

[0006] Furthermore, the value of α is 30°.

[0007] Furthermore, the axial length of the hub body is L1, the axial length of the hub tail is L2 (value is 2.4 mm), and the value of L1:L2 is 2.8 to 3.6.

[0008] Furthermore, the hub body and the hub tail are an integrated structure, and the outer edges of the joints are rounded, and the outer edges of the distal ends of the hub tail are also rounded.

[0009] Furthermore, the proximal diameter of the hub body is R1, the distal diameter of the hub tail is R2, and R1=R2.

[0010] Furthermore, the blade includes an action surface, which is a three-dimensional space curved surface, and the contour line of the action surface includes an inlet edge, an outer edge line, a hub line and an outlet edge.

[0011] Furthermore, the blades are arranged on the outer periphery of the hub body, the vertex of the inlet edge is located near the head of the hub body, and the distance between the vertex of the inlet edge and the end face of the head of the hub body is d, and the value of d is 0.1mm-0.3mm.

[0012] Furthermore, the endpoint of the outer edge profile line close to the proximal end is the starting point of the profile line, and the endpoint close to the distal end is the end point of the profile line. The outer edge profile line is a smooth spatial curve. The curvature of the outer edge profile line along the axial direction of the hub gradually decreases from the starting point of the profile line to the end point of the profile line. At the same time, the curvature change rate of the outer edge profile line along the axial direction of the hub also gradually decreases. The angle between the axial plane where the starting point of the profile line is located and the axial plane where the end point of the profile line is located is the blade deflection angle θ, and the angle of the blade deflection angle θ is 150°~180°.

[0013] Another object of the present invention is to provide a right heart assist device that has both hydraulic performance and hemolytic performance.

[0014] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a catheter and a right heart impeller arranged in the catheter.

[0015] In the above scheme, the frustum-shaped hub tail has a certain flow-guiding and rectifying effect, which can reduce the flow velocity and pressure in the flow field when the blood passes through; and the cone transition is smooth and reasonable, resulting in strong support for blood flowing through the model surface, less likely to escape and flow separation, and a smoother flow field; the shear force in a reasonable flow field is smaller, further improving the hemolytic performance. Therefore, the impeller of this structure can take into account the hydraulic performance and hemolytic performance of the blood pump without setting a guide vane. In addition, due to the improvement of cavitation performance, the impeller rotation is more stable, the noise is small, and it is more patient-friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the front view of the impeller; Figure 2 for Figure 1 A top view of Figure 3 for Figure 1 Left view of Figure 4 is a schematic diagram of a right ventricular assist device; Figure 5 It is a pressure simulation comparison diagram of the impeller in the embodiment and the impeller in the comparative embodiment; Figure 6 It is a comparison diagram of the wall shear stress simulation of the impeller in the embodiment and the impeller in the comparative embodiment; Figure 7 It is a simulation comparison diagram of flow field velocity vector distribution of the impeller in the embodiment and the impeller in the comparative embodiment; Figure 8 It is a simulation comparison curve diagram of the cavitation performance of the impeller in the embodiment and the impeller in the comparative embodiment. DETAILED DESCRIPTION

[0017] To facilitate understanding, we first define the directions involved in the following text: "proximal" and "proximal" refer to the side close to the operator / doctor, and "distal" and "distal" refer to the side away from the operator / doctor, that is, the side close to the heart.

[0018] The hydraulic performance and hemolytic performance of the ventricular assist device are closely related to the structure of the impeller. The structure of the impeller of the ventricular assist device needs to take into account both the hydraulic performance and the hemolytic performance. The considerations for hydraulic performance are mainly the output flow rate and the pressure difference between the inlet and outlet of the ventricular assist device, while the considerations for hemolytic performance are mainly the shear stress to which the blood is subjected during the pumping process and the smoothness of the blood flow. The purpose of the present invention is to improve the hydraulic performance while reducing blood damage by optimizing and improving the impeller structure.

[0019] For the right heart assist device, it pumps blood from the inferior vena cava, bypasses the right atrium and right ventricle, and pumps blood into the pulmonary artery. Therefore, the direction of the impeller pumping blood is from the proximal end of the impeller to the distal end of the impeller. For this reason, the structure of the impeller should also be designed accordingly. Figure 1-Figure 7 The present invention is described in further detail.

[0020] A right heart impeller includes a hub 10 and at least one blade 20 fixed to the periphery of the hub 10. For a right heart assist device, it pumps blood from the inferior vena cava, bypasses the right atrium and the right ventricle, and pumps the blood into the pulmonary artery. Therefore, the direction of blood pumping by the impeller is from the proximal end of the impeller to the distal end of the impeller. Because of this, the structure of the impeller should also be designed accordingly.

[0021] The hub 10 includes a hub body 11 and a hub tail 12 which are connected in sequence from the proximal end to the distal end. The blades 12 are suitable for rotating under the drive of the hub 10 to transport blood from the proximal end of the impeller to the distal end of the impeller. It should be noted that the proximal end of the hub body 11 is generally connected to a driving mechanism, which drives the impeller to rotate to pump blood from the head of the impeller to the tail of the impeller. The "head" and "tail" here are defined according to the direction of blood flow.

[0022] As the key point of the present invention, the hub body 11 is a frustum structure with a radius gradually increasing from the proximal end to the distal end, the hub tail 12 is a frustum structure with a radius gradually decreasing from the proximal end to the distal end, and the axial length of the hub tail 12 is smaller than the axial length of the hub body 11.

[0023] The impeller of the present invention is used in a right heart assist device. After being pushed by the impeller, the blood must pass through the longer end of the cannula before it can be ejected from the outlet of the assist device. Therefore, the requirements for the blood flow rate and energy loss during the blood flow process are relatively high, that is, the requirements for hydraulic performance are relatively high. The diameter of the hub body 11 gradually increases in the direction of blood flow, and the gap between the hub body 11 and the outer cannula becomes smaller and smaller, increasing the blood flow rate. If no structure is set at the tail of the hub body 11, part of the blood flow guided by the hub body 11 will directly hit the outer cannula due to inertia, lose part of the kinetic energy, and cause blood damage. In order to solve the above problems, the prior art usually designs the distal end of the hub into a hemispherical head structure with a relatively rounded top and better blood melting performance. The high-flow blood guided by the hemispherical head will not reduce the blood flow rate when passing through the hemispherical head, ensuring the pressure difference between the impeller inlet and outlet, and improving the hydraulic performance of the assist device. However, when the blood is guided through the surface of the hemispherical head, the blood flow path and velocity distribution will change, the flow field will be turbulent, and the pressure near the tail area will suddenly drop, causing flow separation in this area; when the blood flows through this low-pressure area, the cavitation performance is poor, and during the high-speed rotation of the impeller, the tail area is very likely to induce cavitation initiation, resulting in cavitation, aggravating the vibration and noise of the device; due to the deceleration and turning of the fluid, the pressure and shear force in the flow field are large, resulting in hemolysis. Therefore, this type of impeller usually needs to be used with a guide vane, which can correct the blood flow field, reduce flow separation, avoid unnecessary turbulence and eddy currents in the blood, and reduce blood damage.

[0024] In the present application, the hub tail 12 is set to a frustum-shaped structure, and the gradually shrinking shape can guide the blood to flow in a smoother way, with good flow guidance and stabilization performance, and a more stable flow field, thereby reducing the shear force and flow separation phenomenon; after being gradually guided by the frustum surface, the pressure of the blood gradually decreases, that is, the pressure gradient is small, the required cavitation margin is significantly reduced, and the cavitation performance is significantly improved, which is conducive to the stability of the impeller during rotation. The stable rotation of the impeller can further reduce the mechanical damage to the blood and the stable pumping of the blood.

[0025] In the prior art, some impellers have a tail that is set to be a separate water droplet or a cone-shaped column. The cone-shaped tail guides and concentrates part of the blood flow to the tip, and this part of the blood will collide with each other, causing blood damage on the one hand and energy loss when the blood is mixed on the other hand. The frustum-shaped impeller tail in the application is a plane with a certain diameter. When the outer peripheral surface of the frustum guides the blood to the tail end, the blood will flow to the distal end due to inertia, avoiding blood collision and mixing, with less energy loss, better hemolysis, and high auxiliary efficiency.

[0026] In summary, the cone-shaped hub tail 12 in the present invention has a certain flow-guiding and rectifying effect, which can reduce the flow velocity and pressure in the flow field when the blood passes through; and the cone transition is smooth and reasonable, resulting in strong support for blood flowing through the model surface, less likely to lose flow and flow separation, and a smoother flow field; the shear force in a reasonable flow field is smaller, further improving the hemolytic performance. Therefore, the impeller of this structure can take into account the hydraulic performance and hemolytic performance of the blood pump without setting a guide plate. In addition, due to the improvement of cavitation performance, the impeller rotation is more stable, the noise is small, and it is more patient-friendly.

[0027] As a preferred embodiment of the present invention, the angle between the surface of the hub tail 12 and the axis is α, and the value of α is 25° to 35°. After multiple tests, it was verified that when the value of α is 30°, the hydraulic performance and hemolytic performance of the impeller are in the best state.

[0028] Furthermore, the axial length of the hub body 11 is L1, the axial length of the hub tail 12 is L2, and the value of L1:L2 is 2.8 to 3.6. Because the hub tail 12 is designed mainly to guide blood, an excessively long tail will increase the surface area of ​​the tail region, further increasing the blood flow resistance while also leading to an increase in the risk of hemolysis, thereby causing the efficiency of the ventricular assist device to decrease and the hemolysis value to increase. An appropriate tail length can ensure smooth blood flow while avoiding excessive energy loss and hemolysis risk.

[0029] The hub body 11 and the hub tail 12 are an integrated structure, which are integrally formed during processing, with high dimensional control accuracy, and the outer edges of the joints are rounded. The outer edges of the distal ends of the hub tail 12 are also rounded to further reduce hemolysis.

[0030] As a preferred solution of the present invention, the proximal diameter of the hub body 11 is R1, and the distal diameter of the hub tail 12 is R2, R1 = R2. The values ​​of R1 and R2 are close, which ensures that the cross-sectional areas of blood flowing into and out of the impeller area are similar, which is more conducive to the stable development of the flow field.

[0031] The blade 20 includes an action surface 21, which is a three-dimensional space curved surface. The contour line of the action surface 21 includes an inlet edge 22, an outer edge profile 23, a hub profile 24 and an outlet edge 25. When the blade 20 rotates with the hub 10, the action surface 21 of the blade 20 produces a pumping effect on the blood. Therefore, the structure of the action surface 21 plays a key role in the overall performance of the impeller and even the catheter pump. When the contour line of the action surface 21 is determined, the overall curved surface structure of the action surface 21 can be determined. The outer edge profile 23 is a smooth spatial curve, indicating that the action surface 21 smoothly transitions from the side close to the inlet end to the side close to the outlet end. In the process of blood flowing from the impeller inlet to the outlet, it flows smoothly along the curved surface structure of the action surface 21, which helps to reduce flow losses. At the same time, the blood velocity changes slowly and is evenly distributed in the process of flowing along the action surface 21, which helps to reduce the flow dead zone and reduce blood damage.

[0032] The blades 12 are arranged on the outer periphery of the hub body 11, the apex of the inlet edge 22 is located near the head of the hub body 11, and the distance between the apex of the inlet edge 22 and the end face of the head of the hub body 11 is d, and the value of d is 0.1mm-0.3mm. In other words, the top of the blade 20 contacts the blood earlier than the hub, and this blade forward extension design is helpful to enhance the blood passing capacity of the ventricular assist device, and this design reduces eddy current and turbulence, stabilizes the operation, thereby reducing resistance loss and improving the assist efficiency.

[0033] Furthermore, the endpoint of the outer edge profile 23 close to the proximal end is the starting point of the profile, and the endpoint close to the distal end is the end point of the profile. The outer edge profile 23 is a smooth spatial curve. The curvature of the outer edge profile 23 along the axial direction of the hub gradually decreases from the starting point of the profile to the end point of the profile. At the same time, the curvature change rate of the outer edge profile 23 along the axial direction of the hub 10 also gradually decreases. The angle between the axial plane where the starting point of the profile is located and the axial plane where the end point of the profile is located is the blade deflection angle θ, and the angle of the blade deflection angle θ is 150° to 180°. The blade deflection angle θ can be more intuitively understood as that in the top view projection of the impeller, the angle between the line connecting the starting point of the profile and the axis of the hub 10, and the line connecting the end point of the profile and the axis of the hub 10, the angle formed by the two connecting lines is the blade deflection angle θ. The size of the blade deflection angle θ reflects the length of each blade 20 extending along the circumference of the hub 10. If the blade deflection angle θ is too small, the flow rate may not meet the requirements under high pressure conditions. If the blade deflection angle θ is too large, the flow rate may be too small under low pressure conditions. It has been proved through many experiments that when the blade deflection angle θ is 150° to 180°, the flow rate meets the design requirements.

[0034] In order to verify the beneficial effects of the present invention, a simulation experiment is now conducted on the impellers in the embodiment and the comparative embodiment, wherein the impeller tail in the embodiment is in the shape of a frustum, and the impeller tail in the comparative embodiment is in the shape of a hemispherical head, and the remaining parameters (including the length and diameter of the hub body 11, the deflection angle of the blade 20, the shape of the blade, etc.) are kept consistent. The simulation results are as follows: Figure 5-Figure 8 shown.

[0035] Figure 5 This is a pressure simulation comparison diagram of the impeller in the embodiment and the impeller in the comparative embodiment. The cloud chart shows that the pressure of the blood in the comparative embodiment is significantly higher after passing through the impeller, and the pressure in the embodiment is further reduced, especially the pressure near the tube wall is significantly smaller.

[0036] Figure 6 It is a simulation comparison diagram of the wall shear stress of the impeller in the embodiment and the impeller in the comparative embodiment. The shear stress diagram shows that the shear force at the tail of the impeller hub in the comparative embodiment is larger, and the shear force on the surface of the hemispherical head is larger; the shear force value in the embodiment is further reduced. We can see that the shear force is larger only at the connection between the hub body 11 and the impeller tail 12, and the shear force in other parts is smaller, which significantly improves the hemolytic performance.

[0037] Figure 7 It is a simulation comparison diagram of the flow field velocity vector distribution of the impeller in the embodiment and the impeller in the comparative embodiment. The vector diagram shows that the recirculation area at the tail of the impeller hub in the comparative embodiment is larger and the flow field is unstable, while the recirculation area of ​​the solution in the embodiment is reduced and the flow field is smoother.

[0038] Figure 8It is a comparison curve diagram of the cavitation performance simulation of the impeller in the embodiment and the impeller in the comparative embodiment. By simulating the cavitation performance of the two hubs, the required cavitation margin of the pump in the embodiment is significantly reduced and the cavitation performance is significantly improved.

[0039] like Figure 4 As shown, a right heart assist device, a catheter and a right heart impeller arranged in the catheter. The impeller is assembled in the catheter, and a built-in motor or an external motor drives the impeller to rotate to achieve the purpose of pumping blood.

[0040] The embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to replace some of the technical features therein with equivalents. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is also within the scope of patent protection of this application.

Claims

1. A right-hand impeller, comprising a hub (10) and at least one blade (20) fixed to the outer periphery of the hub (10), characterized in that: The hub (10) comprises a hub body (11) and a hub tail (12) connected in sequence from the proximal end to the distal end, and the blades (12) are suitable for rotating under the drive of the hub (10) to transport blood from the proximal end of the impeller to the distal end of the impeller; The wheel hub body (11) is a frustum structure with a radius that gradually increases from the proximal end to the distal end, the wheel hub tail (12) is a frustum structure with a radius that gradually decreases from the proximal end to the distal end, and the axial length of the wheel hub tail (12) is smaller than the axial length of the wheel hub body (11).

2. The right-hand impeller according to claim 1, characterized in that: The angle between the surface of the wheel hub tail portion (12) and the axis is α, and the value of α is 25° to 35°.

3. The right-hand impeller according to claim 1, characterized in that: The value of α is 30°.

4. The right-hand impeller according to claim 1, characterized in that: The axial length of the hub body (11) is L1, the axial length of the hub tail (12) is L2, and the value of L1:L2 is 2.8 to 3.

6.

5. The right-hand impeller according to claim 1, characterized in that: The hub body (11) and the hub tail (12) are integrally formed, and the outer edges of the joints are rounded, and the outer edges of the distal ends of the hub tail (12) are also rounded.

6. The right-hand impeller according to claim 1, characterized in that: The proximal diameter of the hub body (11) is R1, and the distal diameter of the hub tail (12) is R2, where R1=R2.

7. The right-hand impeller according to claim 1, characterized in that: The blade (20) comprises an action surface (21), the action surface (21) being a three-dimensional space curved surface, and the contour line of the action surface (21) comprises an inlet edge (22), an outer edge profile line (23), a hub profile line (24), and an outlet edge (25).

8. The right-hand impeller according to claim 7, characterized in that: The blades (12) are arranged on the outer periphery of the hub body (11), the apex of the inlet edge (22) is located near the head of the hub body (11), and the distance between the apex of the inlet edge (22) and the end face of the head of the hub body (11) is d, and the value of d is 0.1 mm-0.3 mm.

9. The right-hand impeller according to claim 7, characterized in that: The endpoint of the outer edge profile line (23) close to the proximal end is the profile line starting point, and the endpoint close to the distal end is the profile line ending point. The outer edge profile line (23) is a smooth spatial curve. The curvature of the outer edge profile line (23) along the axial direction of the hub gradually decreases from the profile line starting point to the profile line ending point. At the same time, the curvature change rate of the outer edge profile line (23) along the axial direction of the hub (10) also gradually decreases. The angle between the axial plane where the profile line starting point is located and the axial plane where the profile line ending point is located is the blade deflection angle θ, and the angle of the blade deflection angle θ is 150° to 180°.

10. A right heart assist device, characterized in that: A duct and a right heart impeller according to any one of claims 1 to 9 arranged in the duct.

Images