Centrifugal blood pump

Abstract

Provided is a centrifugal blood pump that can inhibit thrombus formation. A centrifugal blood pump 1 includes a housing 10, an impeller 20 disposed inside the housing 10, and a magnetic drive portion 30. The impeller 20 includes a base 23, a top shroud 24 having a blood introduction opening 241, a plurality of guide portions 26, a rotating shaft member 21 having a lower end portion 211 supported by a lower surface portion 13 of the housing 10 and rotatable about a rotating shaft J, and a first magnet 27 disposed at a lower portion of the base 23. The magnetic drive portion 30 includes a second magnet 312, and drives the impeller 20 to rotate about the rotating shaft J in a state in which the first magnet 27 and the second magnet 312 are magnetically coupled by a magnetic coupling force that acts in such a manner as to attract each other in a vertical direction. An upper surface 242 of the top shroud 24 and a lower surface 121 of an upper surface portion 12 of a blood accommodation portion 11 are formed to be narrow as an outer side in a radial direction of the top shroud 24 approaches an inner side.

Description

Technical Field

[0001] This invention relates to centrifugal blood pumps. Background Technology

[0002] For example, in cardiac surgery, an extracorporeal blood circulation circuit, such as an artificial heart-lung circuit, is used to temporarily replace the patient's cardiopulmonary function. This extracorporeal blood circulation circuit includes a blood pump for flowing blood within the circuit. Centrifugal blood pumps are known as blood pumps that deliver fluid by applying centrifugal force to the blood by rotating an impeller within a pump chamber (blood containment section).

[0003] When a centrifugal blood pump is used for prolonged blood circulation in an extracorporeal blood circulation circuit, blood clots may sometimes form within the pump. When a blood clot forms, blood flow becomes impaired, potentially leading to a decline in the performance of the centrifugal blood pump.

[0004] Conventional designs have disclosed centrifugal blood pumps in which an impeller, supported by an upper bearing and a lower bearing shaft, is rotatably mounted within a housing (see, for example, Patent Document 1). The centrifugal blood pump described in Patent Document 1 has an inlet port located at the top and an outlet port located on the side of its housing. Blood flowing into the housing from the inlet port passes through the upper bearing of the impeller and is propelled radially outward by the centrifugal force generated by the impeller's rotation. The blood propelled radially outward is discharged from the outlet port to the outside of the housing.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-193658 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In the centrifugal blood pump described in Patent Document 1, the impeller is supported by an upper bearing and a lower bearing shaft. Blood flowing into the housing from the inlet port may stagnate in the upper bearing section and form a thrombus. Therefore, it is desirable to inhibit the formation of thrombi.

[0010] The purpose of this invention is to provide a centrifugal blood pump capable of inhibiting thrombus formation.

[0011] Methods for solving problems

[0012] This invention relates to a centrifugal blood pump, comprising: a housing having a blood receiving portion, an inlet port, and an outlet port; the blood receiving portion containing blood and having an upper portion, a lower portion, and a side portion; the inlet port being formed in communication with the blood receiving portion and opening upwards; and the outlet port being formed in communication with the blood receiving portion and opening laterally; an impeller disposed inside the housing and having a base, a top cover, a plurality of guide portions, a rotating shaft member, and a first magnet; the top cover being separately disposed above the base and having a radially centered blood inlet opening; the plurality of guide portions being formed between the base and the top cover and guiding blood introduced from the blood inlet opening radially outwards. The rotating shaft member is axially supported at its lower end on the lower part of the housing and is rotatable about the rotating shaft. The first magnet is disposed at the lower part of the base. A magnetic drive unit is disposed below the blood receiving portion and has a second magnet disposed below the first magnet and coupled to the first magnet by magnetic coupling. When the first magnet and the second magnet are magnetically coupled by magnetic coupling force that acts to attract each other in the vertical direction, the magnetic drive unit drives the impeller to rotate about the rotating shaft. The upper surface of the top cover and the lower surface of the upper part of the blood receiving portion are formed to narrow as they approach the inner side in the radial direction from the outer side of the top cover.

[0013] Additionally, preferably, the upper surface of the top cover is formed as a straight line inclined downward from the radially inner side to the outer side, and the lower surface of the upper part of the blood receiving portion is formed as a straight line inclined downward from the radially inner side to the outer side.

[0014] Additionally, preferably, the angle difference between the upper surface of the top cover and the lower surface of the upper part of the blood receiving portion is 2.5 to 4.0°.

[0015] Furthermore, it is preferable that the lower surface of the impeller is arranged parallel to the upper surface of the lower part of the blood receiving portion.

[0016] The effects of the invention

[0017] According to the present invention, a centrifugal blood pump capable of inhibiting thrombus formation can be provided. Attached Figure Description

[0018] Figure 1 This is a perspective view of one embodiment of a centrifugal blood pump.

[0019] Figure 2 yes Figure 1 A sectional view along line AA.

[0020] Figure 3 This is a three-dimensional view of the impeller of a centrifugal blood pump taken from above.

[0021] Figure 4 This is a three-dimensional view of the impeller of a centrifugal blood pump taken from below. Detailed Implementation

[0022] Hereinafter, an embodiment of the centrifugal blood pump 1 of the present invention will be described with reference to the accompanying drawings. The centrifugal blood pump 1 of the present invention is, for example, a blood pump used in an extracorporeal blood circulation circuit such as an artificial heart-lung circuit to circulate blood.

[0023] like Figure 1 and Figure 2 As shown, the centrifugal blood pump 1 includes a housing 10, an impeller 20 housed inside the housing 10, and a drive unit 30 (magnetic drive unit). The impeller 20 can rotate around the rotation axis J within the pump chamber 11 by the driving force of the drive unit 30.

[0024] like Figure 1 and Figure 2 As shown, the housing 10 has a pump chamber 11 (blood containing part), an inlet port 17, and an outlet port 18. The inlet port 17 and the outlet port 18 are in communication with the interior of the pump chamber 11.

[0025] An impeller 20 is housed in pump chamber 11, temporarily containing blood supplied from inlet port 17. By rotating the impeller 20, the blood contained in pump chamber 11 is discharged to the outside through outlet port 18 due to centrifugal force. Figure 2 As shown, the pump chamber 11 has an upper part 12, a lower part 13, a peripheral wall part 14 (side part) and a lower bearing 15.

[0026] like Figure 2 As shown, the upper surface 12 is positioned above the pump chamber 11. The upper surface 12 is formed in the shape of an annular plate, inclined in a manner that descends from the radially inner side to the outer side. The lower surface 121 of the upper surface 12 is formed in a straight line that slopes downward from the radially inner side to the outer side.

[0027] An inlet port 17 is connected to the upper part of the central part of the upper part 12. The inlet port 17 is formed in communication with the interior of the pump chamber 11 and opens upward. The inlet port 17 extends upward from the upper part of the pump chamber 11 in the same direction as the rotation axis J of the rotation shaft member 21.

[0028] The lower portion 13 is disposed separately from the lower portion of the upper portion 12. The lower portion 13 has a central protrusion 131 formed in the center and protruding upward, and an annular inclined portion 132 formed in a ring shape on the outside of the central protrusion 131.

[0029] A lower bearing 15 is disposed at the center of the radial direction of the central protrusion 131. The lower end 211 of the rotating shaft member 21 of the impeller 20 (described later) is inserted into the lower bearing 15. The lower bearing 15 can support the lower end 211 of the rotating shaft member 21 so that it rotates about the rotating shaft J.

[0030] The inclined annular portion 132 is formed into a downwardly inclined annular shape as it moves from the radially inner side to the outer side. The upper surface 132a of the inclined annular portion 132 is formed into a straight line that slopes downward from the radially inner side to the outer side of the lower portion 13.

[0031] like Figure 2 As shown, the peripheral wall portion 14 forms the peripheral wall of the pump chamber 11 and is formed as a cylindrical wall extending downward from the radially outer end of the upper portion 12. The peripheral wall portion 14 has an upper peripheral wall portion 141 and a lower peripheral wall portion 142.

[0032] The upper peripheral wall portion 141 connects the radially upward end of the upper portion 12 with the circumferentially upward end of the lower portion 13 and extends in the vertical direction. In longitudinal section, the inner surface of the upper peripheral wall portion 141 is formed in an arc-shaped recess on the radially upward side of the upper portion, and is formed obliquely on the lower portion side as it descends from the radially upward side towards the inward side.

[0033] like Figure 1 As shown, an outlet port 18 is connected to the outer surface of the upper peripheral wall portion 141. The outlet port 18 is formed in communication with the interior of the pump chamber 11 and opens to the side. The outlet port 18 extends horizontally on the upper peripheral wall portion 141 of the pump chamber 11 along the tangent of a circle centered on the rotation axis J of the rotating shaft member 21.

[0034] The lower peripheral wall portion 142 extends downward from the lower end of the upper peripheral wall portion 141. The lower peripheral wall portion 142 is formed into a cylindrical shape that is thicker than the upper peripheral wall portion 141. The rotor 31 of the drive device 30, which will be described later, is disposed inside the lower peripheral wall portion 142.

[0035] like Figure 2 As shown, the impeller 20 is rotatably disposed inside the pump chamber 11 of the housing 10 about the rotating shaft J. Figures 2-4 As shown, the impeller 20 has a rotating shaft member 21 capable of rotating around a rotating shaft J, an impeller body 22 connected to the rotating shaft member 21, and multiple impeller-side magnets 27 (first magnets). The impeller body 22 has a base 23, a top cover 24, multiple blades 25 (guide members) (first blade 251, second blade 252) and a shaft connection portion 253.

[0036] The base 23 is disposed at the lower part of the impeller body 22. The base 23 has a horizontal upper panel 231, an inclined panel 232, and an annular protrusion 233.

[0037] The horizontal upper panel 231 is formed into a horizontal annular shape at its radial center. A through hole 231a extending vertically is formed at the radial center of the horizontal upper panel 231. The rotating shaft member 21 is disposed through the through hole 231a.

[0038] The inclined panel 232 is formed as an annular shape that slopes downward from the radially outer end of the horizontal upper panel 231 toward the radially outer side.

[0039] The lower portion of the annular protrusion 233 at the radially outer end of the inclined panel 232 extends in an annular shape along the circumference of the base 23 and protrudes downward. The annular protrusion 233 is formed obliquely as it descends from the radially inner side of the base 23 toward the outer side.

[0040] The lower surface 233a of the annular protrusion 233 is formed as a straight line inclined downwards from the inner side radially towards the outer side of the base 23. For example... Figure 2 As shown, the lower surface 233a of the annular protrusion 233 is arranged parallel to the upper surface 132a of the annular inclined portion 132.

[0041] A plurality of impeller-side magnets 27 are disposed inside the annular protrusion 233. The plurality of impeller-side magnets 27 are arranged at equal intervals along the circumference of the base 23 on the lower part of the outer side in the radial direction. The plurality of impeller-side magnets 27 are each formed as cylinders with an axial length shorter than their diameter, and the upper and lower surfaces are arranged at an angle as they descend from the inner side to the outer side in the radial direction of the base 23.

[0042] like Figures 2-4 As shown, the top cover 24 is disposed facing the base 23 at a position separated from the base 23 above. The top cover 24 is formed into a plate-like annular shape. The top cover 24 is inclined in a manner that descends from the radially inward side to the outward side. The upper surface 242 of the top cover 24 is formed into a straight line that slopes downward from the radially inward side to the outward side.

[0043] A circular blood inlet opening 241, extending vertically through the top cover 24, is formed at the radial center of the top cover 24. The upper part of the rotating shaft member 21 is disposed through the blood inlet opening 241, which allows blood supplied from the inlet port 17 to flow into the pump chamber 11.

[0044] like Figure 2As shown, the outer diameter of the top cover 24 is formed to be approximately the same as the outer diameter of the upper surface of the base 23. The gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is formed in a downwardly inclined manner, decreasing from the radially inward side of the top cover 24 towards the outward side, and is formed to widen from the radially inward side towards the outward side. In other words, the gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is formed to narrow from the radially outward side of the top cover 24 towards the inward side.

[0045] The angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is preferably 2.5 to 4.0°, more preferably 3.0 to 3.5°. In this embodiment, the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is set to 3.0°. The reason for preferring an angle difference θ of 2.5 to 4.0° between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 will be explained later.

[0046] like Figures 2-4 As shown, a plurality of blades 25 are disposed between the base 23 and the top cover 24. Each of the plurality of blades 25 is formed as a plate extending vertically and radially in a manner that connects the base 23 and the top cover 24. The plurality of blades 25 guide blood introduced from the blood inlet opening 241 of the top cover 24 radially outward. In this embodiment, the plurality of blades 25 consists of three first blades 251 and three second blades 252.

[0047] The first blade 251 and the second blade 252 are alternately arranged at equal intervals in the circumferential direction of the top cover 24. The lower edges of the first blade 251 and the second blade 252 are fixed to the upper surface of the base 23. The upper edges of the first blade 251 and the second blade 252 are fixed to the lower surface of the top cover 24. Thus, the base 23 and the top cover 24 are integrated via the first blade 251 and the second blade 252.

[0048] The radially outer ends of the first blade 251 and the second blade 252 extend radially to approximately the same position as the outer ends of the base 23 and the top cover 24.

[0049] The inner ends of each of the three first blades 251 in the radial direction are connected to the shaft connection portion 253 located in the radial center. A rotating shaft member 21 extending in the vertical direction is connected to the shaft connection portion 253 in a through state on the shaft connection portion 253 that connects the inner ends of the three first blades 251.

[0050] The radially inner ends of each of the three second blades 252 are not connected to the rotating shaft member 21, and extend radially to approximately the same position as the outer end of the blood inlet opening 241 of the top shield 24.

[0051] like Figure 3 As shown, the space between the base 23 and the top cover 24, which are arranged vertically opposite each other, is divided into six sections in the circumferential direction by the first blade 251 and the second blade 252, which are adjacent in the circumferential direction. Thus, six guide paths 26 (guide sections) are formed between the base 23 and the top cover 24.

[0052] Six guide paths 26 extend radially from the center of the impeller 20. For each guide path 26, at its radial center, the upper side communicates with a blood inlet opening 241 formed radially at the center of the top shroud 24, and the lower side communicates with a through hole 231a formed radially at the center of the base 23. The guide paths 26 open radially outward at their radially outer ends on the impeller 20. The guide paths 26 guide blood introduced from the blood inlet opening 241 radially outward between the base 23 and the top shroud 24.

[0053] like Figure 2 As shown, the rotating shaft member 21 is configured to pass through the radial center portion of the top cover 24 in the vertical direction and extends in the vertical direction. The rotating shaft member 21 is connected to the shaft connection portion 253 in a state where it passes through the shaft connection portion 253 that connects the inner ends of the three first blades 251.

[0054] The lower end 211 of the rotating shaft component 21 is supported by a lower bearing 15 disposed on the lower part 13 of the housing 10. The lower bearing 15 is located at the center of the lower part 13 of the pump chamber 11.

[0055] like Figure 2 As shown, the upper end 212 of the rotating shaft member 21 is not supported by a bearing and is a free end. That is, the centrifugal blood pump 1 of this embodiment has a bearing structure with a so-called monopivot configuration, where the impeller 20 is supported only at the lower bearing 15. In this embodiment, since the upper end 212 of the rotating shaft member 21 is not supported by a bearing, blood stagnation is unlikely to occur at the upper end 212 of the rotating shaft member 21, reducing blood stasis. Therefore, it is difficult for blood clots to form near the upper end 212.

[0056] The drive unit 30 is disposed below the housing 10. The drive unit 30 has a rotor 31 and a drive shaft 32 capable of rotating the rotor 31 about a rotation axis J. The drive shaft 32 extends from the lower surface of the rotor 31. The drive shaft 32 is connected to a rotation drive source such as an electric motor and is driven to rotate. The rotor 31 has a truncated cone 311 and a plurality of drive-side magnets 312 (second magnets) disposed on the upper surface of the truncated cone 311.

[0057] Below the housing 10, a plurality of drive-side magnets 312 are arranged facing each other below the plurality of impeller-side magnets 27 of the impeller 20 housed inside the housing 10. The plurality of drive-side magnets 312 and impeller-side magnets 27 are arranged in the same number and at equal intervals along the circumference of the truncated cone 311. Each of the drive-side magnets 312 is formed as a cylinder with a length shorter than its diameter in the axial direction, and its upper and lower surfaces are arranged at an angle that decreases radially from the inner side to the outer side of the truncated cone 311.

[0058] When the rotor 31 rotates around the rotation axis J, the drive unit 30 drives the impeller 20 to rotate around the rotation axis J in a state where the impeller-side magnet 27 and the drive-side magnet 312 are magnetically coupled by a magnetic coupling force that acts to attract each other in the vertical direction. For example, the magnetic coupling force between the impeller-side magnet 27 and the drive-side magnet 312 is 12N.

[0059] Next, the operation of the centrifugal blood pump 1 will be explained.

[0060] The rotor 31 of the drive unit 30 rotates around the rotation axis J, thereby magnetically coupling the drive-side magnet 312 and the impeller-side magnet 27 with a magnetic coupling force that attracts each other in the vertical direction. This causes the impeller 20 to rotate stably inside the housing 10 around the rotation axis J.

[0061] In this state, blood is supplied to the interior of the pump chamber 11 from the inlet port 17. The blood supplied from the inlet port 17 is introduced into the six guide paths 26 of the impeller 20 through the blood inlet opening 241 formed in the center of the radial direction of the top shroud 24.

[0062] The blood introduced into the six guide paths 26 is subjected to centrifugal force generated by the rotation of the impeller 20, and moves from the radially inner side to the outer side within the guide paths 26. It flows out from the radially outer end of the guide path 26 into the pump chamber 11 and is discharged to the outside through the outlet port 18.

[0063] Furthermore, blood flowing from the radially outer end of the guide path 26 into the pump chamber 11 passes through the gap S2 between the lower surface 233a of the annular protrusion 233 of the base 23 and the upper surface 132a of the lower part 13 of the pump chamber 11, and moves towards the through hole 231a side of the base 23. The blood that has moved through the gap S2 below the base 23 to the through hole 231a side is introduced into the guide path 26 via the through hole 231a of the base 23. Therefore, a flow of blood that moves below the base 23 and returns to the through hole 231a of the base 23 (so-called secondary flow) is generated. This generates a force that pushes the impeller 20 upward.

[0064] Additionally, blood flowing from the radially outer end of the guide path 26 into the pump chamber 11 passes through the gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11, and moves toward the blood inlet opening 241. The blood that has moved to the blood inlet opening 241 side through the gap S1 above the top cover 24 is introduced into the guide path 26 via the blood inlet opening 241 of the top cover 24.

[0065] Here, the gap S1 is formed to narrow as it moves radially from the outer side to the inner side of the top cover 24. An angular difference θ is provided between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11. Therefore, the blood passing through the gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 generates a pressure that pushes the top cover 24 downwards. Due to the pressure of the blood passing through the gap S1, the impeller 20 is pushed downwards, suppressing its upward movement.

[0066] The following explains the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11. The angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 will be explained from the viewpoints of suppressing the upward floating of the impeller 20 and the viewpoints of hemolysis resistance.

[0067] The upper end 212 of the rotating shaft member 21 of the impeller 20 is not supported by a shaft, while the lower end 211 is supported by a shaft. Therefore, blood stagnation is unlikely to occur at the upper end 212 of the rotating shaft member 21, and thrombus formation is unlikely in the vicinity of the upper end 212. The drive device 30 is driven by magnetic coupling between the impeller-side magnet 27 and the drive-side magnet 312, which act in a manner that attracts each other in the vertical direction, thereby causing the impeller 20 to rotate around the rotating shaft J.

[0068] On the other hand, the lower end 211 of the rotating shaft member 21 of the impeller 20 is supported by a shaft, while the upper end 212 is not supported by a shaft. Furthermore, blood flowing through the gap S2 between the lower surface 233a of the annular protrusion 233 of the base 23 and the upper surface 132a of the lower part 13 of the pump chamber 11 pushes the impeller 20 upwards. Therefore, even though the impeller-side magnet 27 and the drive-side magnet 312 are magnetically coupled by magnetic coupling force, the blood flowing through the gap S2 between the lower surface 233a of the annular protrusion 233 of the base 23 and the upper surface 132a of the lower part 13 of the pump chamber 11 also pushes the impeller 20 upwards, causing the impeller 20 to float and potentially detach from the lower bearing 15.

[0069] In contrast, because the present invention provides an angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11, the spacing of the gap S1 becomes smaller as it moves from the outer side of the top cover 24 radially toward the inner side. Therefore, the pressure of the blood flowing through the gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 can be used to push the impeller 20 downwards from above, thereby suppressing the buoyancy of the impeller 20.

[0070] Here, if the angle difference θ between the upper surface 242 of the top shield 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is increased, the shear force acting on the blood will increase. If the shear force acting on the blood increases, blood cells may be destroyed (hemolysis), and hemolysis resistance cannot be ensured. Therefore, it is necessary to set the angle difference θ between the upper surface 242 of the top shield 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 to an angle that prevents the shear force from becoming too large, thereby ensuring hemolysis resistance.

[0071] Therefore, from the perspectives of suppressing the upward movement of the impeller 20 and ensuring hemolysis resistance, an experiment was conducted to change the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11. Based on the experimental results, an angle difference θ that can suppress the upward movement of the impeller 20 and ensure hemolysis resistance was set.

[0072] In the experiment of varying the angle difference θ, the criteria for suppressing the upward buoyancy of the impeller 20 are set as follows. In this embodiment, the impeller 20 rotates in a magnetically coupled state with a magnetic coupling force of 12N acting between it and the rotor 31 of the drive unit 30, which attracts each other in the vertical direction. In this case, it is known through experiments that, in order to suppress the upward buoyancy of the impeller 20 and enable the impeller 20 to rotate normally, considering the force that pushes the impeller 20 upward through the secondary flow of blood and the magnetic coupling force acting between the impeller 20 and the rotor 31 of the drive unit 30 in the vertical direction, and considering the safety factor, it is preferable that the maximum upward buoyancy of the impeller 20 is 8N or less. Therefore, as a criterion related to the upward buoyancy of the impeller 20, when varying the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11, it is determined that the maximum upward buoyancy of the impeller 20 is 8N or less, which is OK (“○” determination).

[0073] In the experiment involving varying the angle difference θ, the criteria for determining hemolytic resistance were set as follows. Experiments showed that hemolytic resistance was ensured when the shear force was below 900 Pa. Therefore, as a criterion related to hemolytic resistance, when varying the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11, a condition was deemed OK (“○” judgment) when the shear force was below 900 Pa.

[0074] Table 1 below shows the experimental results obtained by determining the maximum buoyancy of the impeller 20 and the maximum shear force of the blood under varying angle differences θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11.

[0075] [Table 1]

[0076]

[0077] In the judgment results, regarding the buoyancy of impeller 20, it is set to "○" when the maximum buoyancy of impeller 20 is below 8N, and set to "×" when the maximum buoyancy of impeller 20 is greater than 8N. Regarding hemolysis resistance, it is set to "○" when the shear force is below 900Pa, and set to "×" when the shear force is greater than 900Pa. If both the judgment criteria for the buoyancy of impeller 20 and hemolysis resistance are met (both are "○"), it is set to "◎" in the comprehensive judgment.

[0078] According to the experimental results shown in Table 1, when the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is 2.5 to 4.0°, the judgment results regarding the buoyancy and hemolytic resistance of the impeller 20 are "○", satisfying the judgment criteria of both parties, and the overall judgment is "◎". Therefore, it is preferable that the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is 2.5 to 4.0°. Moreover, it is more preferable that the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is 3.0 to 3.5°, which is the value on the central side of the range of 2.5 to 4.0°. In this embodiment, the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is set to 3.0°.

[0079] The centrifugal blood pump 1 of this embodiment, as described above, achieves the following effects.

[0080] The centrifugal blood pump 1 comprises a housing 10, an impeller 20, and a magnetic drive unit 30. The impeller 20 is disposed inside the housing 10 and has a base 23; a top cover 24 having a blood inlet opening 241 formed radially in the center; multiple guide paths 26 for guiding blood introduced from the blood inlet opening 241 radially outward; a rotating shaft member 21 whose lower end 211 is axially supported on the lower part 13 of the housing 10 and is rotatable about a rotation axis J; and multiple impeller-side magnets 27 disposed on the lower part of the base 23. The magnetic drive unit 30 drives the impeller 20 to rotate about the rotation axis J in a state where the impeller-side magnets 27 and the drive-side magnets 312 are magnetically coupled by magnetic coupling forces that act in a manner that attract each other in the vertical direction. The upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 are formed to narrow as they approach the inner side radially from the outer side of the top cover 24.

[0081] Therefore, by designing the upper end 212 of the rotating shaft member 21 to be unsupported by bearings, a structure that makes thrombus formation difficult is created. Furthermore, even without bearing support, the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 are formed to narrow radially from the outer side to the inner side of the top cover 24. This allows blood pressure to act from the upper side to the lower side of the impeller 20 by pushing the impeller 20 downwards. Thus, thrombus formation can be suppressed, and the upward movement of the impeller 20 can be prevented, allowing the impeller 20 to rotate stably.

[0082] Furthermore, the upper surface 242 of the top cover 24 is formed into a straight line that slopes downward from the radially inward side to the outward side, and the lower surface 121 of the upper part 12 of the pump chamber 11 is formed into a straight line that slopes downward from the radially inward side to the outward side. Therefore, because the gap S1 between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 gradually narrows, the pressure of blood pushing downward towards the impeller 20 can be stably generated, causing the impeller 20 to rotate more stably.

[0083] Furthermore, the angle difference θ between the upper surface 242 of the top cover 24 and the lower surface 121 of the upper part 12 of the pump chamber 11 is set to 2.5 to 4.0°. This suppresses the buoyancy of the impeller 20 while ensuring hemolytic resistance.

[0084] Furthermore, the lower surface 233a of the annular protrusion 233 of the impeller 20 is arranged parallel to the upper surface 132a of the annular inclined portion 132 of the lower part 13 of the pump chamber 11. As a result, since the pressure of the blood flowing in the gap S2 is constant, the impeller 20 can rotate stably.

[0085] The preferred embodiments of the centrifugal blood pump of the present invention have been described above, but the present invention is not limited to the above embodiments and appropriate modifications can be made.

[0086] In the above embodiment, the rotating shaft member 21 is arranged in the radial center portion that penetrates the top cover 24 in the vertical direction, but it is not limited to this. Since the upper end of the rotating shaft member 21 is not supported by a shaft, the upper end side of the rotating shaft member 21 may not penetrate the top cover 24.

[0087] Explanation of reference numerals in the attached figures

[0088] 1. Centrifugal blood pump

[0089] 10. Shell

[0090] 11. Pump Room (Blood Containment Section)

[0091] 12. Upper face

[0092] 13 Lower part

[0093] 14. Peripheral wall (side wall)

[0094] 17 Entry Ports

[0095] 18 Export Ports

[0096] 20 Impeller

[0097] 21 Rotating shaft components

[0098] 23 Base

[0099] 24 Top Shield

[0100] 25 Blades (Guiding Components)

[0101] 26. Guidance Path (Guidance Section)

[0102] 27. Impeller-side magnet (first magnet)

[0103] 30. Drive unit (magnetic drive section)

[0104] 121 Lower surface of the upper part of the pump chamber (blood containment section)

[0105] 132a Upper surface of the inclined portion of the ring (upper surface of the lower portion)

[0106] 211 Lower end

[0107] 233a Lower surface of the annular protrusion (lower surface of the impeller)

[0108] 241 Blood inlet opening

[0109] 242 Upper surface of the top cover

[0110] 312 Drive-side magnet (second magnet)

[0111] J Rotation axis

[0112] θ angle difference

Claims

1. Centrifugal blood pump, which has the following features: A housing having a blood receiving portion, an inlet port, and an outlet port, the blood receiving portion containing blood and having an upper part, a lower part, and a side part, the inlet port being formed in communication with the blood receiving portion and opening upward, and the outlet port being formed in communication with the blood receiving portion and opening to the side; An impeller is disposed inside the housing and has a base, a top cover, a plurality of guides, a rotating shaft member, and a first magnet. The top cover is disposed separately from the top of the base and has a blood inlet opening formed radially in the center. The plurality of guides are formed between the base and the top cover and guide blood introduced from the blood inlet opening radially outward. The lower end of the rotating shaft member is axially supported on the lower part of the housing and is rotatable about the rotating shaft. The first magnet is disposed on the lower part of the base. and A magnetic drive unit is disposed below the blood containing section and has a second magnet disposed below the first magnet and coupled to the first magnet by magnetic coupling. When the first magnet and the second magnet are magnetically coupled by a magnetic coupling force that attracts each other in the vertical direction, the magnetic drive unit drives the impeller to rotate about the rotation axis. The upper surface of the top cover and the lower surface of the upper part of the blood receiving portion are formed to narrow as they move radially from the outer side to the inner side of the top cover. A through hole extending in the vertical direction is formed in the base. The through hole connects the gap between the lower surface of the impeller and the upper surface of the lower part of the blood receiving section. At the radial center of the top cover, the upper side of the guide portion communicates with the blood inlet opening, and the lower side of the guide portion communicates with the through hole formed in the base. The angle difference between the upper surface of the top cover and the lower surface of the upper part of the blood containing part is 2.5 to 4.0°.

2. The centrifugal blood pump according to claim 1, wherein, The upper surface of the top cover is formed as a straight line that slopes downwards from the radially inward side to the outward side. The lower surface of the upper part of the blood containing part is formed as a straight line that slopes downward from the radially inner side to the outer side.

3. The centrifugal blood pump according to claim 1 or 2, wherein, The lower surface of the impeller is arranged parallel to the upper surface of the lower part of the blood receiving section.

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