JP5743567B2 - Centrifugal blood pump - Google Patents

Description

  The present invention relates to a centrifugal blood pump.

  In operations such as the heart, blood pumps are used outside the body to maintain the patient's blood circulation. For example, in the conventional centrifugal blood pump shown in Patent Document 1, an impeller 120 is rotatably supported in a hollow casing 110 composed of an upper side 111 and a lower side 115 (FIGS. 7 to 9). The impeller 120 has a magnet 128 built in, and can be rotated by an external motor (not shown) with a built-in magnet disposed on the outside lower side of the casing 110. The casing 110 includes an inlet port 112 through which blood flows and an outlet port 113 through which blood flows out.

  Patent Document 1 discloses the installation position and installation direction of the inlet port 112. The blood inlet port 112 provided in the casing 110 is provided at a position offset from the top of the conical portion constituting a part of the upper side 111 of the casing 110 (FIG. 8). In addition, the inlet port 112 is oriented so that its central axis 112c is substantially parallel to the inner surface 111s of the conical portion of the casing 110 and the side surface 120s of the impeller 120 (FIG. 9). Accordingly, it is possible to prevent the blood flowing from the inlet port 112 from colliding with the upper shaft 127, the inner surface of the conical portion, and the side surface of the impeller to cause hemolysis.

  Patent Document 2 discloses a centrifugal blood pump in which an inlet port is installed in a vertical direction at the top of a casing. In Patent Document 2, an upper bearing that pivotally supports the upper end of the rotation shaft of the impeller is held by three bearing columns at the opening position of the inlet port. The blood flow from the inlet port flows into the casing through the gap between the upper bearing and the three bearing columns. That is, the blood flow flowing from the inlet port hits the back surface of the upper bearing (on the opposite side of the bearing surface that supports the rotation shaft of the impeller).

JP 2005-28156 A JP 2002-85553 A

  The impeller 120 of the conventional centrifugal blood pump 100 (FIG. 9) receives a downward force by a magnet of an external motor (not shown) disposed on the lower side of the casing 110 in a stationary state. However, when the centrifugal blood pump 100 is operated and the impeller 120 begins to rotate, the impeller 120 receives an upward force due to the interaction between the rotation of the impeller 120 and blood circulating in the centrifugal blood pump 100. When the rotational speed increases, the upper shaft 127 of the impeller 120 comes into strong contact with the upper bearing member 117 fixed to the casing 110.

  Usually, the space between the upper shaft 127 and the upper bearing member 117 (referred to as “upper sliding interface”) is lubricated by the blood in the centrifugal blood pump 100, and the friction coefficient is kept low. However, when the impeller 120 rotates at a high speed and the upper shaft 127 strongly contacts the upper bearing member 117, blood does not easily enter the upper sliding interface, and the friction coefficient increases. As a result, frictional heat is generated at the upper sliding interface, and the temperature around the upper sliding interface (the portion near the interface of the upper shaft 127 and the portion near the interface of the upper bearing member 117) locally increases. .

When blood comes into contact with a member having a body temperature higher than that of the body temperature, it tends to form a thrombus on the surface of the member. Once the thrombus is formed, the blood clots around the thrombus, and the size of the thrombus increases (this is referred to as “thrombus growth”).
As described above, when the impeller 120 rotates at a high speed, the temperature around the upper sliding interface (the vicinity of the interface of the upper shaft 127 and the vicinity of the interface of the upper bearing member 117) easily rises locally. Likely to happen. When the thrombus grows on the surface in the vicinity of the interface of the upper shaft 127 and / or the surface in the vicinity of the interface of the upper bearing member 117, the blood flow between the upper sliding interface and the centrifugal blood pump 100 is hindered. . That is, the upper sliding interface cannot be lubricated by blood, the friction coefficient of the upper sliding interface is further increased, and further frictional heat is generated. Eventually, the upper shaft 127 and / or the upper bearing member 117 is thermally deformed, and the centrifugal blood pump 100 does not function.

  Therefore, in order to provide a centrifugal blood pump that operates stably over a long period (several hours to several weeks), it is necessary to maintain lubrication of the upper sliding interface during high-speed rotation of the impeller. However, Patent Documents 1 and 2 do not disclose a configuration for solving this problem.

  Therefore, an object of the present invention is to provide a centrifugal blood pump that can maintain the lubrication of blood to the upper sliding interface during high-speed rotation of the impeller.

  The centrifugal blood pump of the present invention is a centrifugal blood pump including a casing having an inlet port through which blood flows in and an outlet port through which the blood flows out, and an impeller housed in the casing, wherein the impeller is The upper bearing member and the lower bearing member are rotatably fixed in the casing, and the central axis of the inlet port is inclined with respect to the rotation axis of the impeller, and the upper bearing member The bearing surface is arranged in a blood flow basin from the inlet port.

  In the present invention, the term “flow region of blood flow from the inlet port” refers to a range where there is a blood flow that substantially maintains the flow velocity and direction when flowing from the inlet port. Specifically, this term refers to the area in which blood is flowing after it flows from the inlet port but before it hits the components of the centrifugal blood pump. The blood flow velocity of blood flowing through this basin is fast. Further, when the rotation speed of the impeller is increased, the blood flow velocity circulated by the centrifugal blood pump is increased, so that the blood flow velocity in this basin is also increased.

  In the centrifugal blood pump of the present invention, the “bearing surface of the upper bearing member” constituting the upper sliding interface is disposed in the blood flow basin, so that blood stays around the bearing surface. There is no blood clot. Furthermore, the following effects can be obtained by positively applying blood to the bearing surface.

  First, since a blood flow having a high flow velocity hits the bearing surface, blood tends to enter the upper sliding interface. In particular, when the rotation speed of the impeller is increased, the blood flow velocity is increased, and blood infiltration into the upper sliding interface is promoted. Therefore, the lubrication of blood to the upper sliding interface during high-speed rotation of the impeller can be maintained.

  Secondly, since the blood that has just flowed in (which is maintained at a temperature of about body temperature) continues to hit the bearing surface, the frictional heat generated at the upper sliding interface can be efficiently removed. Since the local temperature rise around the upper sliding interface is suppressed, the formation of thrombus is suppressed. That is, the problem of “blocking of blood intrusion to the lubrication of the upper sliding interface by the grown thrombus” can be suppressed and the lubrication of the upper sliding interface can be maintained.

In addition, when it is going to apply a blood flow from the orthogonal | vertical direction with respect to a bearing surface, the rotating shaft of an impeller becomes obstructive. In addition, when blood flow is applied to the bearing surface from the horizontal direction, the bearing surface is normally a concave curved surface in order to stably support the upper shaft, so the blood flow is applied to the concave curved surface. Can not be enough. Therefore, in order to reliably apply the blood flow to the bearing surface, it is desirable to apply the blood flow from an oblique direction with respect to the bearing surface.
In the centrifugal blood pump of the present invention, since the central axis of the inlet port is inclined with respect to the rotation axis of the impeller, the blood flow can be applied to the bearing surface of the upper bearing member from an oblique direction.

  In the centrifugal blood pump according to the present invention, the bearing surface of the upper bearing member is disposed in the blood flow region from the inlet port, and the central axis of the inlet port is inclined with respect to the rotation axis of the impeller. By doing so, it is possible to efficiently maintain the lubrication of blood to the upper sliding interface during the high speed rotation of the impeller.

It is a perspective view of the centrifugal blood pump which concerns on embodiment of this invention. It is a top view of the centrifugal blood pump which concerns on embodiment of this invention. It is sectional drawing in the XX line of the centrifugal blood pump which concerns on embodiment of this invention shown in FIG. It is an exploded sectional view of a centrifugal blood pump concerning an embodiment of the present invention ((a)-(c)). It is a partial expanded sectional view of the centrifugal blood pump which concerns on embodiment of this invention. It is a partial expanded sectional view of the centrifugal blood pump which concerns on embodiment of this invention. It is a perspective view of the conventional centrifugal blood pump. It is a top view of the conventional centrifugal blood pump. It is sectional drawing in the YY line of the conventional centrifugal blood pump shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions and positions (for example, “up”, “down”, “right”, “left” and other terms including those terms) are used as necessary. . The use of these terms is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Moreover, the part of the same code | symbol which appears in several drawing shows the same part or member.

A centrifugal blood pump 1 according to this embodiment shown in FIGS. 1 to 3 includes a hollow casing 10 and an impeller 20 accommodated in the casing 10. The casing 10 includes a casing upper part 11 and a casing lower part 15. The casing 10 (casing upper part 11) has an inlet port 12 through which blood flows in the direction of arrow Bi and an outlet port 13 through which blood flows out in the direction of arrow Bo.
The inlet port 12 has a central axis 12c formed in a direction inclined at an angle θ with respect to the rotation axis 20r of the impeller 20.

  The impeller 20 is rotatably fixed (supported) to the casing 10 by an upper bearing member 24 and a lower bearing member 16. Specifically, between the casing 10 and the impeller 20, there is an upper sliding member 34 including an upper bearing member 24 and an upper shaft 14 received therein, and a lower bearing member 16 and a lower side received therein. A lower sliding member 36 composed of the shaft 26 is formed.

In the centrifugal blood pump 1 of the present invention, the bearing surface 24 s of the upper bearing member 24 is disposed inside the blood flow area Br from the inlet port 12. In the present invention, the term “flow region Br of blood flow from the inlet port 12” refers to a range in which blood flows after flowing from the inlet port 12 and before hitting the components of the centrifugal blood pump (FIG. 4 ( a)). Therefore, as shown in FIG. 4A, when the upper shaft 14 is present in the vicinity of the opening of the inlet port 12 (the portion opened inside the casing 10), the blood flow basin Br is The region Bx where the blood flow is blocked by the shaft 14 is not included.
Since the blood flowing through the blood flow region Br maintains the flow velocity when entering from the inlet port 12, the blood flow velocity is faster than the blood flowing through other regions of the centrifugal blood pump 1.

In the centrifugal blood pump 1, an interface (upper sliding interface 34 s) of the upper sliding member 34 is configured by the bearing surface 24 s of the upper bearing member 24 and the sliding surface 14 s of the upper shaft 14. In the present invention, since the bearing surface 24s is arranged in the blood flow region Br, the blood flow with a high flow velocity hits the bearing surface 24s, and the blood easily enters the upper sliding interface 34s. Therefore, the upper sliding interface 34s can be lubricated with blood.
When the rotation speed of the impeller 20 increases, the upper sliding interface 34s comes into strong contact, and blood hardly enters the upper sliding interface 34s. On the other hand, when the rotation speed of the impeller 20 is increased, the blood flow velocity in the blood flow region Br is increased, and the infiltration of blood into the upper sliding interface 34s is promoted. Therefore, in the centrifugal blood pump 1 of the present invention, even when the rotational speed of the impeller 20 is increased, the amount of blood necessary for lubrication can be maintained at the upper sliding interface 34s.

Further, in the present invention, the bearing surface 24s is disposed in the blood flow region Br, so that blood striking the sliding surface 14s can remove frictional heat generated at the upper sliding interface 34s. Therefore, it is possible to suppress the generation of a thrombus (due to a local temperature increase) around the upper sliding interface 34s.
Note that the temperature of blood does not substantially increase due to heat removal by blood. This is because the upper sliding interface 34 s is sufficiently lubricated, so that the amount of heat generated at the upper sliding interface 34 s is small, and the blood does not stay in the bloodstream basin Br. This is because it is distributed.

  In the centrifugal blood pump 1 of the present invention, blood with a high flow velocity hits the bearing surface 24s of the upper sliding interface 34s, so that thrombus hardly occurs around the bearing surface 24s.

  In the present invention, “the bearing surface 24s of the upper bearing member 24 is disposed inside the blood flow region Br from the inlet port 12” means that at least a part of the bearing surface 24s is a blood flow region. It means that it is arranged inside Br. For example, as shown in FIGS. 3 and 4 (a), a part of the bearing surface 24s of the upper bearing member 24 (the part facing the opening of the inlet port 12) is disposed inside the blood flow region Br. It only has to be done. If at least a part of the bearing surface 24s is disposed inside the blood flow region Br, the effect of promoting blood intrusion into the upper sliding interface 34s as described above, and frictional heat from the upper sliding interface 34s are generated. It is clear that the effect of removing is obtained. Therefore, if a part of the bearing surface 24s is disposed inside the blood flow region Br, the lubrication effect of the upper sliding interface 34s can be obtained, and thrombus generation is suppressed.

  In the centrifugal blood pump 1 of the present invention, the central axis 12 c of the inlet port 12 is inclined with respect to the rotation axis of the impeller 20. As shown in FIG. 4A, the blood flow basin Br has a range corresponding to the diameter of the inlet port 12 from the opening of the inlet port 12 along the central axis 12 c of the inlet port 12. In the blood flow region Br, the blood flows in the direction of the central axis 12c. In order to promote the invasion of blood flow into the upper sliding interface 34 s, the bearing surface 24 s of the upper bearing member 24 (usually a concave curved surface as shown in FIG. 5) and the upper sliding of the upper shaft 14. It is desirable to apply the blood flow toward the gap between the interface 34 (upper sliding interface 34s) with the motion 34 (usually a convex curved surface as shown in FIG. 5).

In other words, in the present invention, the central axis 12c of the inlet port 12 is preferably inclined with respect to the rotation axis 20r of the impeller 20 so that the blood flow from the inlet port 12 flows into the gap of the upper sliding interface 34s. Thereby, the effect of promoting the invasion of blood flow into the upper sliding interface 34s is improved.
Further, if the blood flow can flow into the gap of the upper sliding interface 34s, the region where the frictional heat is generated (the bearing surface 24s of the upper bearing member 24 and the sliding surface 14s of the upper shaft 14 come into contact with each other). The blood flow can be efficiently flowed to the vicinity of the area. Therefore, the efficiency of removing frictional heat from the upper sliding interface 34s can be improved.

  In particular, when the angle θ formed by the center axis 12c of the inlet port 12 and the rotation axis 20r of the impeller 20 is 20 ° to 60 °, blood flow from the inlet port 12 flows in through the gap of the upper sliding interface 34s. Since it becomes easy to do, it is preferable.

The upper bearing member 24 may be provided on the impeller 20 or the casing 10. In particular, it is preferable that the upper bearing member 24 is provided on the impeller 20 and the upper shaft 14 is provided on the casing 10. The centrifugal blood pump 100 of FIG. By providing the upper bearing member 24 on the impeller 20, the bearing surface 24 s faces upward, and blood flow from the inlet port 12 formed in the casing upper portion 11 is easily hit. Further, by providing the upper bearing member 24 on the impeller 20, the position of the sliding surface 14s can be lowered (compared to the conventional centrifugal blood pump 100 (FIG. 9)).
Further, since the diameter of the upper shaft 14 is smaller than that of the upper bearing member 24, when the upper shaft 14 is disposed in the casing 10, the opening of the entrance port 12 can be provided close to the upper shaft 14. That is, the opening of the entrance port 12 can be installed at a position close to the bearing surface 24s.
Thus, by providing the upper bearing member 24 in the impeller 20 and providing the upper shaft 14 in the casing 10, the bearing surface 24s can be easily disposed in the blood flow region Br.

  Further, when manufacturing a centrifugal blood pump 1 for newborns and children (for example, a small centrifugal blood pump 1 having a blood filling amount of 10 ml to 35 ml), miniaturization of the parts size of the entire pump becomes a problem. In particular, the upper bearing member 24 and the inlet port 12 need to be arranged close to a narrow range. However, if both the upper and lower bearing members 24, 16 and the upper and lower shafts 14, 26 are changed to small dimensions, the contact pressure on the bearing surface is increased, and there is a concern that these parts may be damaged. Therefore, from the viewpoint of preventing breakage of the member, even in the centrifugal blood pump 1 for newborns and children, the upper and lower bearing members 24, 16 having the same size and diameter as those of the conventional centrifugal blood pump 1 for adults, It is desirable to use the lower shafts 14,26.

  However, in the case of the conventional centrifugal blood pump 100 as shown in FIG. 9, the inlet port 112 and the upper bearing member 117 interfere with each other, so that the inlet port 112 and the upper bearing member 117 cannot be disposed close to each other. Therefore, a small centrifugal blood pump could not be manufactured using the upper and lower bearing members 117 and 116 and the upper and lower shafts 127 and 126 of the adult centrifugal blood pump 100.

  In the artificial blood pump 10 of the present embodiment, the upper bearing member 24 is disposed on the impeller 20, and the upper shaft 14 is disposed on the casing 10, so that the dimensions of the upper bearing member 24 and the upper shaft 14 are not changed. The upper bearing member 24 and the inlet port 12 can be arranged close to each other within a narrow range. Therefore, the centrifugal blood pump 1 of the present embodiment is suitable for downsizing. Moreover, since the upper shaft 14 provided in the casing 10 of the centrifugal blood pump for newborns and children and the lower shaft 26 provided in the impeller 20 can share those of a general adult centrifugal blood pump, a plurality of types of centrifugal blood are provided. It is possible to share parts across pumps.

  Further, the centrifugal blood pump 1 for newborns and children is used at a higher rotational speed than the general centrifugal blood pump 1 for adults. For example, the rotational speed of the centrifugal blood pump 1 for adults is approximately 4000 revolutions / minute, while the centrifugal blood pump 1 for newborns and children is approximately 6000 revolutions / minute. As described above, since the centrifugal blood pump 1 of the present invention is suitable for use at a high rotational speed, it is suitable for the neonatal and infant centrifugal blood pumps 1.

  As shown in FIG. 5, the bearing surface 24 s of the upper bearing member 24 and the sliding surface 14 s of the upper shaft 14 can be curved surfaces having different curvatures. In particular, considering the dimensions of the centrifugal blood pump 1 and the wear resistance of the sliding surface 14s, the bearing surface 24s is a concave spherical surface having a radius of curvature of 1 mm to 6 mm, and the sliding surface 14s is a convex having a radius of curvature of 1 mm to 5 mm. It is preferable to use a spherical surface.

  As shown in FIG. 3, it is preferable that the casing 10 includes a lower bearing member 16, and the impeller 20 includes a lower shaft 26 that is supported by the lower bearing member 16. As can be seen from FIG. 3, the lower bearing member 16 can be embedded in the thin casing lower portion 15. When driving the centrifugal blood pump 1, an external motor is installed below the centrifugal blood pump 1, and the impeller 20 is rotated by the magnetic force between the magnet of the external motor and the magnet 28 of the impeller 20. If the thickness of the casing lower part 15 can be reduced as in the present embodiment, the distance between the magnet of the external motor and the magnet 28 of the impeller 20 can be reduced, so that the driving energy of the centrifugal blood pump 1 can be reduced.

  As shown in FIG. 6, the bearing surface 16 s of the lower bearing member 16 and the sliding surface 26 s of the lower shaft 26 can be curved surfaces having different curvatures. In particular, considering the dimensions of the centrifugal blood pump 1 and the wear resistance of the sliding surface 26s, the bearing surface 16s is a concave spherical surface with a radius of curvature of 1 mm to 6 mm, and the sliding surface 26s is a convex with a radius of curvature of 1 mm to 5 mm. It is preferable to use a spherical surface.

Below, the material suitable for each structural member is explained in full detail.
(Casing 10)
The casing 10 is made of a material having translucency and a material having high biological safety so that the impeller 20 and flowing blood can be visually recognized. Further, from the viewpoint of preventing infection, all components of the centrifugal blood pump 1 are disposable (disposable). Therefore, a material that is easy to reduce costs, has good workability (for example, a material that can be injection-molded), and is suitable for disposal is preferable. Specifically, for example, a plastic material such as polycarbonate is suitable.

(Upper bearing member 24, lower bearing member 16)
The upper bearing member 24 and the lower bearing member 16 support the upper shaft 14 and the lower shaft 26 for a long time. Therefore, the upper bearing member 24 and the lower bearing member 16 are made of a material that has biosafety, a relatively small friction coefficient with the shafts 14 and 26, and excellent wear resistance. Specifically, polymer materials such as ultra high molecular weight polyethylene (UHMWPE), cross-linked polyethylene, and polyetheretherketone are suitable.

(Upper shaft 14, lower shaft 26)
The upper shaft 14 and the lower shaft 26 are rod-shaped members having a small diameter, and support the impeller 20 that rotates at high speed. Therefore, the upper shaft 14 and the lower shaft 26 are made of a material having biosafety, high strength, and excellent wear resistance. Specifically, for example, ceramic materials such as alumina, silicon carbide, silicon nitride, and tetragonal stabilized zirconia, and biocompatible metal materials (titanium alloy, CoCrMo alloy, SUS316L, and those obtained by surface-hardening them) are used. Is preferred.

(Impeller 20)
The impeller 20 is rotated by an external motor. The material used for the impeller 20 is preferably lightweight so that even a small output / small external motor can be rotated at high speed. Suitable materials include plastic materials such as polycarbonate.

(Magnet 28)
The magnet 28 incorporated in the impeller 20 transmits the rotational energy of the external motor to the impeller 20 by magnetic force. In order to reliably control the rotation of the impeller 20, a magnet having a strong magnetic force is used as the magnet 28. Specifically, rare earth magnets such as neodymium magnets are suitable.

Since the centrifugal blood pump 1 of the present invention can maintain the lubrication of blood to the upper sliding interface, the centrifugal blood pump 1 is less likely to be abnormal due to insufficient lubrication. Therefore, a stable function can be exhibited over a long period (several hours to several weeks).
In addition, the centrifugal blood pump 1 of the present invention is suitable for the centrifugal blood pump 1 for newborns and children because it does not easily generate thrombus even when rotated at high speed.

DESCRIPTION OF SYMBOLS 1 Centrifugal blood pump 10 Casing 11 Casing upper part 12 Inlet port 12c Center axis of inlet port 13 Outlet port 14 Upper shaft 14s Sliding surface of upper shaft 14r Radius of sliding surface of upper shaft 15 Casing lower part 16 Lower bearing member 16s Lower Bearing surface of side bearing member 16r Radius of bearing surface of lower bearing member 20 Impeller 20r Rotating shaft of impeller 21 Bottom surface of impeller 24 Upper bearing member 24s Bearing surface of upper bearing member 24r Radius of bearing surface of upper bearing member 26 Lower side Shaft 26s Sliding surface of lower shaft 26r Radius of sliding surface of lower shaft 28 Magnet 34 Upper sliding member 34s Upper sliding interface 36 Lower sliding member Bi Blood inflow direction Bo Blood outflow direction Br Inlet port Basin of blood flow from

Claims (7)

A casing having an inlet port through which blood flows and an outlet port through which the blood flows out;
An impeller housed in the casing, and a centrifugal blood pump comprising:
The impeller is rotatably fixed in the casing by an upper bearing member and a lower bearing member,
The impeller includes the upper bearing member, and the casing includes an upper shaft supported by the upper bearing member;
The casing includes a casing upper part and a casing lower part,
The inlet port is provided in the upper part of the casing, and a central axis of the inlet port is inclined with respect to a rotation axis of the impeller.
The bearing surface of the upper bearing member is disposed in the blood flow basin from the inlet port ,
In the blood flow basin, the blood flow maintains a flow velocity and direction when flowing from the inlet port . The upper bearing member is made of a polymer material,
The centrifugal blood pump according to claim 1 , wherein the upper shaft is made of a ceramic material. The bearing surface of the upper bearing member is a spherical surface with a radius of curvature of 1 mm to 6 mm,
The centrifugal blood pump according to claim 1 or 2 , wherein the sliding surface of the upper shaft is a spherical surface having a curvature radius of 1 mm to 5 mm. The centrifugal blood pump according to any one of claims 1 to 3 , wherein an angle formed by the central axis of the inlet port and the rotation axis of the impeller is 20 ° to 60 °. The casing includes the lower bearing member;
The centrifugal blood pump according to any one of claims 1 to 4 , wherein the impeller includes a lower shaft that is pivotally supported by the lower bearing member. The lower bearing member is made of a polymer material,
6. The centrifugal blood pump according to claim 5 , wherein the lower shaft is made of a ceramic material. The centrifugal blood pump according to any one of claims 1 to 6 , wherein the centrifugal blood pump is a centrifugal blood pump for newborns and children having a blood filling amount of 10 to 35 ml.

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