Ventricular auxiliary device and blood pump thereof

Abstract

The invention provides a ventricular assist device and a blood pump thereof. The blood pump comprises a pump shell and an impeller, the impeller comprises a rotor part and a plurality of blades arranged on the rotor part, the blood pump further comprises a flow guide cone arranged basically opposite to the blood inlet, the front edge of at least one blade extends towards the radial inner side to the position above the flow guide cone, and the front edge of at least one blade extends towards the radial inner side to the position above the flow guide cone. The lower side of the front edge of at least one blade is provided with an avoiding part, the radius of the flow guide cone is defined as RC, the height of the flow guide cone is defined as HC, and a cylinder with the central axis of the blood inlet as the axis, the top face passing through the cone top of the flow guide cone, the radius of the cylinder is RC, and the height of the cylinder is HC is obtained. And the avoiding part is constructed to enable the at least one blade to avoid the space occupied by the cylinder. According to the blood pump, blood cavitation can be reduced or avoided while high hydraulic performance is maintained, blood damage is reduced, and blood compatibility is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a ventricular assist device and a blood pump thereof. BACKGROUND

[0002] The blood pump is an important component of the ventricular assist device. When designing the blood pump, the hydraulic performance and blood compatibility are important performance indicators to be considered.

[0003] For example, the patent with publication number CN106574628B discloses an impeller including a plurality of non-inducing (i.e., fully radial) blades, so that there is no axial flow or mixed flow component at the leading edge portion 210 of the blade 204, thereby potentially reducing incident-induced cell damage. However, this is at the expense of the hydraulic performance, since the blade has a small action area and interacts with the blood entering the inlet at a later time, resulting in a decrease in the pumping efficiency of the impeller and the hydraulic performance.

[0004] To improve the hydraulic performance, some blood pumps choose to extend the blades as far as possible towards the blood inlet. For example, the patent with publication number US7435059B2 discloses an impeller including main blades and shunt blades fixed on an annular base, wherein the main blades extend further towards the blood inlet in a substantially radial direction compared to the shunt blades, and only a small gap is maintained between the main blades and the tapered tip in the direction of the impeller axis. However, the pressure in the inlet area is low, and after the suction effect of the impeller, cavitation of the blood is easy to occur, which causes damage to the red blood cells in the blood, resulting in poor blood compatibility. SUMMARY

[0005] One of the purposes of the present application is to provide a ventricular assist device and a blood pump thereof, which can reduce or avoid blood cavitation, reduce blood damage, and improve blood compatibility while maintaining high hydraulic performance.

[0006] In a first aspect of the present application, a blood pump is provided, which includes a pump shell and an impeller. The pump shell includes a blood inlet in a central region and a blood outlet in a peripheral region, and a pump cavity is formed inside the pump shell. The impeller is arranged in the pump cavity and includes a rotor portion and a plurality of blades arranged on the rotor portion. The impeller can be driven to rotate around its rotation axis, so as to pump blood from the blood inlet to the blood outlet.

[0007] The blood pump further comprises a flow cone arranged opposite to the blood inlet, the impeller is arranged around the flow cone, and a gap is formed between the rotor of the impeller and the flow cone; characterized in that: the leading edge of at least one of the blades extends to above the flow cone in the radial direction, and an avoiding portion is arranged on the lower side of the leading edge of the at least one blade, the radius of the flow cone is defined as RC, and the height of the flow cone is defined as HC, so that a cylinder with the center axis of the blood inlet as the axis, the top surface passing through the top of the flow cone, the radius RC and the height HC are obtained, and the avoiding portion is configured to enable the at least one blade to avoid the space occupied by the cylinder.

[0008] In a second aspect of the present application, an extracorporeal ventricular assist device is provided, which comprises a motor and the blood pump as described above, the blood pump is detachably connected with the motor, and the motor can drive the impeller of the blood pump to rotate to pump blood from the blood inlet to the blood outlet.

[0009] In a third aspect of the present application, an implantable ventricular assist device is provided, which comprises a motor and the blood pump as described above, the blood pump is integrally formed with the motor, and the motor can drive the impeller of the blood pump to rotate to pump blood from the blood inlet to the blood outlet.

[0010] In the present application, the leading edge of the main blade extends to above the flow cone in the radial direction, the fluid acting area of the main blade is increased, the leading edge of the main blade can interact with the blood entering from the blood inlet as early as possible, the pumping efficiency of the impeller is improved, and the hydraulic performance of the whole blood pump is improved; at the same time, a large enough avoiding portion is arranged on the lower side of the leading edge of the main blade, so that the main blade can completely avoid the low pressure area near the flow cone, the blood backflowing through the secondary flow channel replenishes the low pressure area near the flow cone, and then the blade exerts suction on the blood, thereby avoiding cavitation caused by too low local pressure, reducing blood damage, and improving the blood compatibility of the blood pump. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 FIG. 1 is a schematic view of a ventricular assist device in an embodiment of the present application;

[0012] Figure 2 FIG. 4 is a structural schematic view of a blood pump in an embodiment of the present application;

[0013] Figure 3 FIG. 6 is a top view of an impeller in an embodiment of the present application;

[0014] Figure 4 FIG. 8 is a schematic view of an arc-shaped conical surface in other embodiments of the present application;

[0015] Figure 5Fig. 1 is a structural schematic diagram of a blood pump without the avoidance portion of the present application.

[0016] Figures 1-5 Reference signs are explained as follows:

[0017] 10 - ventricular assist device;

[0018] 100 - blood pump;

[0019] 110 - pump housing; 111 - blood inlet; 1110 - inner wall surface; 112 - blood outlet;

[0020] 120 - impeller; 121 - rotor portion; 1211 - upper end surface; 122 - blade; 123 - main blade; 124 - shunt blade; 1231 - leading edge; 1232 - upper edge; 1233 - lower edge;

[0021] 130 - pump cavity;

[0022] 140 - flow cone; 141 - conical surface; 142 - conical top;

[0023] 150 - avoidance portion; 151 - first edge; 152 - second edge;

[0024] 200 - motor. DETAILED DESCRIPTION

[0025] In order to make the person skilled in the art better understand the scheme of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0026] Please refer to Figure 1 , Figure 1 Fig. 1 is a structural schematic diagram of a ventricular assist device in an embodiment of the present application, which comprises a blood pump 100 and a motor 200. The motor 200 can drive the impeller of the blood pump to rotate to realize the pumping of blood. In the present embodiment, the blood pump and the motor are detachably connected to form an extracorporeal ventricular assist device. In other feasible embodiments, the blood pump and the motor are integrally formed to form an implantable ventricular assist device.

[0027] Please continue to refer to Figure 2 and Figure 3 , Figure 2 Fig. 2 is a structural schematic diagram of a blood pump in an embodiment of the present application, Figure 3The image shows a top view of the impeller in an embodiment of this application. The blood pump 100 includes a pump housing 110 and an impeller 120. The pump housing 110 includes a blood inlet 111 located in its central region and a blood outlet 112 located in its peripheral region. A pump chamber 130 is formed inside the pump housing 110. The impeller 120 is housed in the pump chamber 130 and can be driven to rotate about its axis of rotation OX, thereby pumping blood from the blood inlet 111 to the blood outlet 112.

[0028] The blood inlet 111 has a central axis O1, and the blood outlet 112 has a central axis O2. In this embodiment, the rotation axis OX of the impeller 120 coincides with the central axis O1 of the blood inlet 111, that is, the impeller 120 rotates around the central axis O1 of the blood inlet 111. In other alternative embodiments, the rotation axis OX of the impeller 120 is offset relative to the central axis O1 of the blood inlet 111. This is advantageous in a suspended blood pump because the fluid pressure at various points around the outer periphery of the impeller is not symmetrical about the central axis O1 of the blood inlet. The asymmetrical fluid pressure causes the impeller to tend to deviate from the central axis O1. If an external force is applied to forcibly control the rotation axis OX of the impeller 120 to coincide with the central axis O1 of the blood inlet 111, it will not only lead to additional power consumption, but also increase the heat generation, thus making the thermal management of the blood pump more complicated.

[0029] In this embodiment, the central axis O1 of the blood inlet 111 and the central axis O2 of the blood outlet 112 are perpendicular to each other, that is, the blood pump 100 is a centrifugal pump; in other optional embodiments, the central axis O1 and the central axis O2 are not perpendicular to each other, and the two maintain an acute angle of less than 90° or an obtuse angle of greater than 90°, that is, the blood pump 100 is configured as an oblique flow pump.

[0030] In this embodiment, the impeller 120 can be suspended in the pump chamber 130. There are many ways to suspend the impeller 120 in the pump chamber 130, such as magnetic suspension, hydraulic suspension, magnetic-hydraulic hybrid suspension, etc., which are not limited here. In other optional embodiments, the impeller 120 is rotatably supported in the pump chamber 130 by mechanical bearings.

[0031] The blood pump 100 also includes a guide cone 140 disposed substantially opposite to the blood inlet 111, and an impeller 120 disposed around the guide cone 140. The guide cone 140 is capable of guiding the blood entering the pump chamber 130 from the blood inlet 111.

[0032] In this embodiment, the guide cone 140 has a generally straight conical surface 141. In other alternative embodiments, such as... Figure 4 As shown in (a) and 4(b), the guide cone 140 has an arcuate cone surface 141 that protrudes outward or is recessed inward.

[0033] The impeller 120 comprises a ring-shaped rotor portion 121 and a plurality of blades 122 arranged on the rotor portion 121. The blades 122 are fixedly arranged on the upper end surface 1211 of the rotor portion 121 close to the blood inlet 111. The rotor portion 121 is rotationally driven to drive the plurality of blades 122 to rotate around the rotation axis OX.

[0034] In the embodiment, the side of the blades 122 away from the rotor portion 121 is open. In other alternative embodiments, the side of the blades 122 away from the rotor portion 121 is further provided with an annular upper end cover (not shown in the figure).

[0035] As shown in Figure 2 , the blood enters the pump cavity 130 from the blood inlet 111 and flows from the center to the periphery of the pump cavity under the joint action of the flow guide cone 140 and the blades 122. The gap between adjacent blades forms a main flow channel A1, as shown by the hollow solid arrow. Figure 2 At the same time, the gap between the rotor portion 121 and the pump shell 110 and the flow guide cone 140 forms a secondary flow channel A2, as shown by the hollow dashed arrow. Figure 2 The blood flowing along the main flow channel A1 is partially collected in the peripheral area of the pump shell and flows out from the blood outlet 112, and the other part flows back to the center of the blood pump along the secondary flow channel A2 and re-enters the main flow channel A1.

[0036] In the embodiment, the blades 122 comprise main blades 123 and shunt blades 124. The main blades 123 and the shunt blades 124 are arranged at intervals in the circumferential direction. The radial length of the main blades 123 is greater than the radial length of the shunt blades 124. The leading edge 1231 of the main blades 123 extends further to the radially inner side above the flow guide cone than the shunt blades 124, i.e., in the projection plane perpendicular to the central axis O1, the main blades 123 at least partially overlap the conical surface 141 of the flow guide cone. This increases the fluid acting area of the main blades and enables the leading edge 1231 of the main blades to interact with the blood entering from the blood inlet 111 early, thereby improving the pumping efficiency of the impeller and the overall hydraulic performance of the blood pump. Preferably, in the projection plane perpendicular to the central axis O1, the radial distance from the leading edge 1231 of the main blades to the central axis O1 is not greater than 70% of the radius of the flow guide cone, thereby further ensuring the length of the main blades extending to the radially inner side, thereby significantly improving the overall hydraulic performance of the blood pump. In other alternative embodiments, the blades 122 are not distinguished as main blades and shunt blades, i.e., all the blades 122 are main blades, and the leading edges of all the blades 122 extend to the radially inner side above the flow guide cone.

[0037] The more the leading edge 1231 of the main blade extends to the radially inner side, the larger the action area of the main blade 123 is, and the better the hydraulic performance is, however, when the leading edge 1231 of the main blade extends to the inner wall surface 1110 of the blood inlet 111, the blood entering the pump cavity from the blood inlet 111 will impact the upper edge 1232 of the main blade, thereby causing damage to blood cells, therefore, in the present example, the leading edge 1231 of the main blade is substantially flush with the inner wall surface 1110 of the blood inlet in the radial direction, so as to reduce the damage to blood cells while improving the hydraulic performance as much as possible.

[0038] Cavitation (also known as cavitation) is a crucial problem in fluid pumps, especially for blood pumps. Blood is a special liquid that can transport oxygen to cells and carry away carbon dioxide, so there are many gas nuclei in blood. When blood passes through a low pressure area, the gas nuclei will expand under the action of the internal and external pressure difference to form bubbles. When the blood carrying the bubbles passes through a high pressure area again, the bubbles break, producing a strong shock wave, causing damage to the blood, greatly increasing the risk of hemolysis and thrombosis.

[0039] The inventors of the present application found that the cavitation of a blood pump is different from that of an industrial centrifugal pump. The cavitation bubbles of a blood pump first appear near the lower side of the leading edge of the blade, that is, Figure 5 The area shown by the dashed oval S, as shown in the simulation analysis results of the structure shown in Figure 5 The simulation analysis results of the structure shown in Figure 5 If the leading edge of the blade is close to the outer contour of the flow cone, as shown in

[0040] To reduce the possibility of cavitation, the present patent provides a relief portion 150 at the lower side of the leading edge of the main blade 123, defines the radius of the flow cone 140 as RC and the height of the flow cone 140 (i.e. the height of the projection of the conical surface 141 of the flow cone in the direction of the central axis O1) as HC, and the relief portion 150 is configured such that the main blade 123 can avoid the space occupied by the cylinder with the central axis O1 as the axis, the top surface passing through the cone top 142, the radius RC and the height HC.

[0041] By setting the avoidance portion 150 of a sufficient size under the leading edge of the main blade 123, the main blade 123 can completely avoid the low pressure area near the flow cone, and the blood flowing back through the secondary flow channel A2 can supplement the low pressure area near the flow cone, and then the blade can exert suction on the blood, thereby avoiding cavitation caused by excessively low local pressure.

[0042] The avoidance portion 150 is set to form a first edge 151 oriented in the axial direction and a second edge 152 oriented in the radial direction on the main blade 123; the first edge 151 and the second edge 152 are connected to each other to jointly enclose the profile of the avoidance portion under the leading edge of the main blade 123.

[0043] In the embodiment, the lowest point of the second edge 152 is substantially flush with the apex 142 of the flow cone in the axial direction, and preferably the entire second edge 152 is substantially flush with the apex 142 of the flow cone in the axial direction, so that the main blade 123 can have the largest possible fluid acting area under the premise of completely avoiding the low pressure area of the flow cone 140, further improving the pumping efficiency of the impeller and the overall hydraulic performance of the blood pump.

[0044] In the embodiment, the lower end point of the first edge 151 is substantially flush with the inner wall of the rotor portion 121 in the radial direction, and preferably the entire first edge 151 is substantially flush with the inner wall of the rotor portion 121 in the radial direction, thereby avoiding forming an obstruction to the secondary flow channel A2, so that the blood flowing out through the secondary flow channel can sufficiently supplement the low pressure area near the flow cone, thereby further effectively inhibiting the occurrence of cavitation; at the same time, such design can also avoid the blood flowing out of the secondary flow channel impacting the lower edge 1233 of the main blade, thereby avoiding blood injury.

[0045] If the second edge 152 is completely perpendicular to the central axis O1, a relatively sharp right angle will be formed between the second edge 152 and the leading edge 1231 of the main blade, and between the second edge 152 and the first edge 151, which is extremely unfavorable for the blood compatibility of the blood pump. Therefore, in the embodiment, the second edge 152 is inclined downward from the radial inner side to the radial outer side, so that an obtuse angle is formed between the second edge 152 and the leading edge 1231 of the main blade, and between the second edge 152 and the first edge 151, thereby further improving the blood compatibility of the blood pump.

[0046] An angle between the second edge 152 and a plane perpendicular to the central axis O1 is α, the larger the angle α, the larger the obtuse angle formed between the second edge 152 and the leading edge 1231 of the main blade, and between the second edge 152 and the first edge 151, which is more conducive to improving the blood compatibility; however, if the angle α is too large, it will affect the action area of the main blade and the blood, resulting in a decrease in the action area, a decrease in the pumping efficiency, and a decrease in the hydraulic performance; therefore, in the present embodiment, the angle α is 5°-30°; preferably, the angle α is 10°-20°.

[0047] The principles and implementation manners of the present application are described herein by using specific examples, and the above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that, for those skilled in the art, without departing from the principles of the present application, the present application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A blood pump, comprising a pump housing and an impeller, the pump housing comprising a blood inlet at a central region and a blood outlet at a peripheral region, the pump housing defining a pump cavity inside, the impeller being disposed in the pump cavity, the impeller comprising a rotor portion and a plurality of blades disposed on the rotor portion, the impeller being drivable to rotate about an axis of rotation thereof to pump blood from the blood inlet to the blood outlet; The blood pump further comprises a flow cone arranged substantially opposite to the blood inlet, the impeller is arranged around the flow cone, and a gap is formed between a rotor portion of the impeller and the flow cone; characterized in that: a leading edge of at least one of the blades extends radially inwards above the flow cone, and a relief is formed on an underside of the leading edge of the at least one blade, the relief being configured to enable the at least one blade to clear a space occupied by a cylinder having a radius of RC and a height of HC, the cylinder having an axis of the central axis of the blood inlet, a top surface of the cylinder passing through an apex of the flow cone.

2. The blood pump of claim 1, wherein, The relief forms a first edge that is generally axially oriented and a second edge that is generally radially oriented on the at least one blade.

3. The blood pump of claim 2, wherein, A lower end point of the first edge is generally flush with an inner wall of the rotor portion in a radial direction.

4. The blood pump of claim 3, wherein, The entire first edge is generally flush with the inner wall of the rotor portion in the radial direction.

5. The blood pump of claim 2, wherein, A lowest point of the second edge is generally flush with the apex of the flow cone in an axial direction.

6. The blood pump of claim 5, wherein, The entire second edge is generally flush with the apex of the flow cone in the axial direction.

7. The blood pump of claim 2, wherein, The second edge is inclined downward from a radially inner side to a radially outer side.

8. The blood pump of claim 7, wherein, An included angle a between the second edge and a plane perpendicular to the central axis of the blood inlet is 5° to 30°.

9. The blood pump of claim 1, wherein, In a projection plane perpendicular to the central axis of the blood inlet, a radial distance of the leading edge of the at least one blade to the central axis of the blood inlet is not greater than 70% of the radius RC of the flow cone.

10. The blood pump of claim 1, wherein, The leading edge of the at least one blade is generally flush with an inner wall surface of the blood inlet in the radial direction.

11. An extracorporeal ventricular assist device, characterized in that The ventricular assist device comprises a motor, and the blood pump of any one of claims 1-10, the blood pump being detachably coupled to the motor, the motor being capable of driving the impeller of the blood pump to rotate to pump blood from the blood inlet to the blood outlet.

12. An implantable ventricular assist device, comprising: The ventricular assist device comprises a motor, and the blood pump of any one of claims 1-10, the blood pump being integrally formed with the motor, the motor being capable of driving the impeller of the blood pump to rotate to pump blood from the blood inlet to the blood outlet.

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