Blood pump

Abstract

To provide a blood pump.SOLUTION: A blood pump 1 includes a pump casing 2 having a blood inflow port 5 and a blood outflow port 6 connected by a passage 7, and an impeller 3 disposed in the pump casing 2. The impeller 3 includes a blade 4, and the impeller 3 is rotatably supported in the pump casing 2 by bearings 10 and 20. The surface of the impeller 3 faces the surface of the pump casing 2 separated from the surface of the impeller 3 by a gap 31, the gap 31 being fluid-connected to the passage 7 at a gap transition point 36. A wash-away channel 30 is fluid-connected to the passage 7 through a first opening 34 and to the gap 31 through a second opening 35. The first opening 34 of the wash-away channel 30 is disposed in a region of the impeller 3 so as to cause a blood flow to reach the gap transition point 36 from the first opening 34 through the wash-away channel 30 and the gap 31 under the pressure higher than the pressure at the gap transition point 36.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blood pump implanted in a patient to assist the patient's heart. In particular, the blood pump may be used as a "bridge to recovery" device that temporarily assists the patient's heart until it fully recovers.

[0002] Various types of blood pumps are known, such as axial flow blood pumps, centrifugal blood pumps, or hybrid blood pumps in which blood flow is generated by both axial and radial forces. The blood pump may be inserted into a patient's blood vessel, such as the aorta, using a catheter, or may be placed in the thoracic cavity. The blood pump generally includes a pump casing having a blood flow inlet and a blood flow outlet connected by a passage. An impeller equipped with blades for transporting blood is rotatably supported within the pump casing to cause blood flow from the blood flow inlet to the blood flow outlet along the passage.

[0003] The impeller is supported within the pump casing by at least one bearing, but the bearing may be of a different type depending on the intended use of the blood pump, for example, whether the blood pump is intended for short-term use (a few hours or a few days) or long-term use (a few weeks or a few years). Various types of bearings are known, such as contact bearings and non-contact bearings. In non-contact bearings, for example, in magnetic bearings where the bearing surfaces "levitate" due to repulsive magnetic forces, the bearing surfaces do not contact each other. Generally, contact bearings may include all types of bearings, such as sliding bearings, pivot bearings, hydrodynamic bearings, hydrostatic bearings, ball bearings, or any combination thereof, where the bearing surfaces may be in at least partial contact at any point during pump operation (i.e., always or intermittently). In particular, contact bearings may be "blood-infiltrating bearings" where the bearing surfaces have blood contact. Contact bearings can heat up during use and are prone to mechanical wear due to contact between the rotating bearing surface and the stationary bearing surface during pump operation. It is desirable to supply a cooling fluid to the bearing, such as blood itself. In non-contact bearings, the bearing surfaces do not have physical contact and are separated by gaps that fluid-connect to passages or other fluid supply parts. Similarly, other gaps between the impeller and the pump casing should be flushed, for example, on the downstream front surface of the impeller, to avoid blood coagulation and clogging.

[0004] Configurations for rinsing gaps or bearing surfaces within a blood pump are disclosed, for example, in U.S. Patent Publication No. 2011 / 0238172A1. A flush channel extends through the impeller and is in fluid communication with the passage and gaps through first and second openings. The pressure distribution within the pump casing, when the pressure increases downstream along the impeller, generates blood flow through the gaps and flush channel. Blood enters the gap at the downstream end of the impeller and flows through the flush channel towards the passage area at a lower pressure. This flush flow has the disadvantage of being dependent on the rotational speed of the impeller, as a pressure difference must be created to generate the blood flow. Other forces, such as centrifugal force and reaction forces in the opposite direction of the flush flow, must also be overcome. In another embodiment disclosed in U.S. Patent Publication No. 2011 / 0238172A1, the inlet opening of the flush channel is located at the upstream end of the impeller, in which case the impeller is supported within the pump casing by a hydrodynamic bearing. Auxiliary blades at the downstream end of the impeller are provided to generate a flush flow through the flush channel and gaps in the direction from the low-pressure area to the high-pressure area. [Overview of the project] [Problems that the invention aims to solve]

[0005] Therefore, the main object of the present invention is to provide a blood pump in which blood flow stagnation, blood coagulation, and clogging in the gaps between the rotating and stationary parts of the blood pump, particularly between the stationary and rotating parts of the bearings or impeller and the pump casing, are effectively avoided independently of the rotational speed or operating conditions of the pump. A further object of the present invention is to provide a blood pump that can effectively flush out the gaps. Yet another object of the present invention is to provide a blood pump that can effectively cool contact bearings. [Means for solving the problem]

[0006] The primary objective is achieved by a blood pump having the features of independent claim 1 in accordance with the present invention. Preferred embodiments and further developments of the present invention are specified in claims dependent on the independent claim.

[0007] Like known blood pumps, the blood pump according to the present invention comprises a pump casing having a blood inlet and a blood outlet connected by a passage. The pump casing may be understood as comprising all the stationary parts of the blood pump. An impeller or rotor is disposed within the pump casing so as to be rotatable about an axis of rotation which may be the longitudinal axis of the impeller, and the impeller comprises blades sized and shaped to transport blood along the passage from the blood inlet to the blood outlet. At least one bearing is provided to rotatably support the impeller. The surface of the impeller faces the surface of the pump casing, which is spaced apart from the surface of the impeller by a gap, the gap is fluidly connected to the passage at the gap transition point. To allow the gap to be flushed, at least one flush channel extends through the impeller and is fluidly connected to the passage through a first opening and to the gap through a second opening.

[0008] In contrast to known blood pumps, the first opening of the flush channel is positioned in the impeller region such that, during pump operation, it is under a pressure higher than the gap transition point, directing blood flow from the first opening through the flush channel and gap to the gap transition point. In other words, since the first opening of the flush channel, i.e., the inlet opening of the flush channel, is in the high-pressure region of the impeller, and the gap transition point is, for example, downstream of the impeller where the pressure is lower, the flush flow is directed in the "forward" direction, i.e., toward the blood outlet of the pump casing. Thus, flushing of the forward flow is created by utilizing this pressure difference that occurs during the operation of the blood pump, particularly by taking advantage of the local pressure gradient within the flush channel. This has the advantage that, independently of the rotational speed and operating conditions (e.g., preload, afterload, initial forward flow magnitude), the necessary pressure difference is always present during pump operation, especially at the start of operation when the impeller rotation begins and the rotational speed is slow, particularly below the design speed of the blood pump. In contrast, in known blood pumps where the flush flow is directed in the "reverse" direction, a pressure difference must be established, which takes some time, during which the flush flow may be slow or stagnant. This can lead to blood coagulation and clogging in the gaps, flush channels, or both. Furthermore, the reverse flow must overcome the forces generated by the primary flow direction, which can also lead to stagnation of the flush flow and consequently to blood coagulation and clogging. According to the present invention, the flush flow is present in the "forward" direction throughout the entire operating time of the blood pump, and in particular, utilizes the pressure distribution within the pump casing during pump operation. This flow can be further amplified by an auxiliary pump, as will be described in more detail later. However, it will be understood that such an auxiliary pump is not essential for the functionality of the present invention.

[0009] In a preferred embodiment, the first opening of the flush channel may be located in the downstream half of the impeller. During pump operation, the pressure increases along the length of the impeller, particularly in the region where the impeller blades are located. Therefore, a higher pressure exists in the downstream half of the impeller than in the upstream half. According to the present invention, since the high pressure at the first opening of the flush channel is required to be higher than the gap transition point, more specifically, it is preferable to position the first opening in the downstream half of the impeller. More preferably, the first opening may be located in the downstream third, downstream quarter, or downstream fifth of the impeller. In particular, it is advantageous to position the first opening as close as possible to the downstream end of the impeller, for example, within the last 10% of the impeller's length in the downstream direction.

[0010] With respect to the pressure distribution, the first opening of the flush channel is preferably located in an area of ​​the impeller where, during pump operation, the pressure is higher than the intermediate pressure, and more preferably substantially the maximum pressure, relative to the pressure distribution along the length of the passage on which the impeller is mounted. The high pressure difference between the first opening of the flush channel and the gap transition point improves the flush flow from the first opening of the flush channel to the gap transition point.

[0011] To further improve the flush flow, the impeller may be shaped to create high pressure, particularly at the first opening of the flush channel, to support the aforementioned pressure distribution within the pump. The flush flow may be further improved by providing an auxiliary pump operationally associated with the flush channel, which supplies blood through the flush channel toward a gap transition point. The auxiliary pump may be at least partially formed by the at least one flush channel, in that the flush channel extends through the impeller in a direction having at least one tangential component. In other words, the second pump may be at least partially formed by the at least one flush channel, which may be sized, shaped and positioned to supply blood through the flush channel toward a bearing. Thus, the flush flow is sometimes referred to as a dynamic flush flow.

[0012] Dynamic flushing flow is particularly useful for contact bearings or "blood-infiltrating bearings" because it increases the amount of blood delivered to the bearing to flush and cool it compared to pumps without an auxiliary pump. Cooling of the bearing can be further improved by effectively dissipating heat from the bearing surface. For this purpose, the bearing may include a highly conductive material such as stainless steel, which can dissipate heat better than, for example, ceramics or titanium. It may be advantageous to provide a bearing with at least two components, in particular when the bearing surface is made of a smooth and durable material such as ceramics, provided, for example, in the form of a ceramic cap, and the part of the bearing facing away from the bearing surface is made of a highly conductive material such as stainless steel.

[0013] In one embodiment, the wash channel may extend linearly through the impeller and be offset relative to the axis of rotation. In particular, the wash channel may extend in a plane parallel to the axis of rotation. By providing an arrangement having a linear wash channel that is oblique to the axis of rotation, i.e., does not intersect with the axis of rotation, it is possible to direct a dynamic wash flow into the wash channel.

[0014] In another embodiment, the flush channel may be curved and extend from the first opening in a direction rotating around the axis of rotation, particularly along a helical shape. The helical shape shall be understood as any curved, spiral, helical, or other curved shape of any length in the direction around the axis of rotation. Such a shape is advantageous because it can support a dynamic flush flow.

[0015] Preferably, the flush channel extends from the first opening at an angle to the impeller surface in a circumferential direction opposite to the direction of rotation. In particular, in contrast to a washing channel that extends perpendicular to the impeller surface, the angled inlet opening facilitates blood entering the flush channel and increases the flow rate through the flush channel. This effect can be further improved by selecting an appropriate angle. For example, the angle may be less than 20°, preferably less than 15°, and more preferably less than 10°. The flush channel may extend from the first opening substantially tangentially to the impeller surface, in other words, at a very small angle to the impeller surface. However, it is important that the angle is circumferential opposite to the direction of rotation, in other words, that the first opening is open in the direction of rotation, in order to increase the amount of blood flowing through the flush channel compared to an arrangement in which the flush channel extends perpendicular to the impeller surface.

[0016] In one embodiment, the distance between the second opening and the rotation axis is less than or equal to the distance between the first opening and the rotation axis. In other words, downstream, the flush channel extends toward the rotation axis. Preferably, the distance between the first opening and the rotation axis is as short as possible to reduce the centrifugal force that the flush flow in the flush channel must overcome. In other words, the distance between the first opening and the second opening in the radially inward direction should be as short as possible. Furthermore, it is preferable that the distance between the rotation axis and the first opening is significantly shorter than the distance between the rotation axis and the gap transition point, for example, less than half (50%), less than 40%, or even less than 30%. This configuration can be an improvement over axial flow or mixed blood pumps in centrifugal blood pumps, i.e., it can increase the distance between the first opening and the gap transition point.

[0017] The impeller may extend along the axis of rotation and have a central opening for receiving a bearing, with a second opening fluidly connected to the central opening. Furthermore, the flushing channel may be oriented substantially radially toward the axis of rotation at the second opening. This can improve bearing rinsing and, by extension, bearing cooling.

[0018] Preferably, the first opening of the wash channel is located adjacent to one of the impeller blades on the forward side of the blade with respect to the direction of rotation (generally referred to as the positive pressure side of the blade). In this area, the pressure is higher than in the area on the reverse side of the blade (generally referred to as the negative pressure side of the blade), thereby improving the dynamic wash flow through the wash channel. In one embodiment, the first opening may be located on the forward side of the blade and the second opening on the reverse side of the blade, i.e., both openings are located on the radially outer surface of the impeller, and the wash channel extends downward and across the blade. In another embodiment, the wash channel may extend within the blade, so that the first opening is located on the forward side of the blade and the second opening is located on the blade, particularly on the radially outer edge of the blade. It should be understood that the wash channel is in fluid communication with the area being washed.

[0019] As described, the performance or output of the auxiliary pump can be improved by a specific configuration of the flush channel passing through the impeller, such as a straight or curved flush channel, which may extend at an angle to the surface of the impeller. The performance of the auxiliary pump may be further improved by the cross-section of the first opening of the flush channel. The cross-section of the first opening may be circular or non-circular. If the flush channel has a circular cross-section and extends at an angle to the surface of the impeller, this results in a non-circular cross-section, such as an elliptical cross-section. In one embodiment, the first opening may be formed by an end portion of the flush channel that is at least partially exposed by the flush channel being inclined with respect to the surface of the impeller. In other words, the first opening may be elongated on the surface of the impeller, which can further increase the amount of blood entering the flush channel during the operation of the blood pump.

[0020] In another embodiment, the projection extends into the first opening of the flush channel and is sized and shaped in particular to increase blood flow into the flush channel through the first opening compared to the cross-section of the first opening without the projection. The shape of the first opening without the projection may be either circular or non-circular. The projection is positioned on the opposite side of the first opening with respect to the rotational direction and acts as an "airfoil" to facilitate the inflow of blood into the first opening and thereby improve the performance of the auxiliary pump. Alternatively, or in addition, the impeller may include wings extending radially from there and positioned adjacent to the first opening of the flush channel and behind the first opening with respect to the rotational direction. Preferably, the wings extend over the first opening of the flush channel and are open in the rotational direction to allow blood to enter the first opening. The wings form a pocket that collects blood during the rotation of the impeller and directs the collected blood into the first opening. To achieve a similar effect, the impeller may be provided with a nose or projection having a first opening such that the cross-section of the first opening extends at an angle with respect to the surface of the impeller, preferably at an angle greater than 45°, more preferably at an angle of 90°, and is open in the rotational direction. This can significantly increase the amount of blood flowing into the flush channel.

[0021] Preferably, the blood pump comprises two or more of the flush channels described above, which may be arranged symmetrically with respect to the axis of rotation. In particular, the blood pump may comprise two, three, four, five, or six flush channels.

[0022] In addition to the size, shape, and arrangement of the flush channels that form at least part of the auxiliary pump, the auxiliary pump may further comprise grooves or blades formed on the surface of the impeller. Such auxiliary grooves or blades may be located on the downstream front of the impeller to assist blood flow through the flush channels toward the bearings.

[0023] In one embodiment, the impeller may have a downstream portion that extends radially outward, and the first opening of the wash channel is disposed in said portion. In particular, said portion is conically tapered in the downstream direction and radially outward. That portion may be formed integrally with the impeller or separately. The performance of the auxiliary pump can be further improved by arranging the first opening in a portion that extends radially of the impeller and orienting it in a direction opposite to the main direction of blood flow through the passageway. Thereby, the first opening can capture more blood and the performance of the auxiliary pump is improved. The blades of the impeller may extend over said portion.

[0024] The above summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings.

Brief Description of the Drawings

[0025] <000L085>Cross-sectional view of a blood pump according to the present invention for extracorporeal use. L [Figure 1A] Cross-sectional view of a blood pump according to the present invention for extracorporeal use. [Figure 2] Cross-sectional view of a blood pump according to the present invention designed as a catheter pump. [Figure 3] Perspective view of the impeller. [Figure 4a] Various views showing a portion of the impeller. [Figure 4b] Various views showing a portion of the impeller. [Figure 4c] Various views showing a portion of the impeller. [Figure 4d] Various views showing a portion of the impeller. [Figure 5a] View showing another embodiment of the impeller. [Figure 5b] View showing another embodiment of the impeller. [Figure 6a] This figure shows another embodiment of a part of the impeller. [Figure 6b] This figure shows another embodiment of a part of the impeller. [Figure 7] This is a cross-sectional view showing a part of a blood pump according to another embodiment. [Figure 8] This is a cross-sectional view showing a portion of an impeller according to another embodiment. [Figure 9] This is a cross-sectional view showing a portion of an impeller according to another embodiment. [Figure 10] This is a cross-sectional view showing a part of an impeller according to yet another embodiment. [Figure 11] This is a cross-sectional view showing a part of a blood pump according to another embodiment. [Modes for carrying out the invention]

[0026] Referring to Figure 1, a cross-sectional view of blood pump 1 is shown. Blood pump 1 is designed for extracorporeal, extracardiac, or extraluminal applications and comprises a pump casing 2 having a blood inlet 5 and a blood outlet 6. During operation, the pump casing 2 is located outside the patient's body, and the blood inlet 5 and blood outlet 6 are connected to their respective connectors (particularly the inflow from the heart and the outflow into the aorta). Figure 2 shows an embodiment similar to Figure 1, differing in that it is designed as a catheter pump 1'. The blood inlet 5' is at the end of a flexible catheter 50 positioned through a cardiac valve such as the aortic valve, and during use, the blood outlet 6' is located on the side of the pump casing 2' and is located within a cardiovascular vessel such as the aorta. Blood pump 1' is connected to a catheter 51, and an electrical wire 52 extends through the catheter 51 to drive pump 1'. Both blood pumps 1 and 1' function in the same way. It will be understood that all the features described later are applicable to both embodiments.

[0027] Blood is transported along a passage 7 connecting a blood inlet 5 and a blood outlet 6. An impeller 3 is provided to transport blood along the passage 7 and is rotatably mounted within the pump casing 2 around a rotation axis 9 by a first bearing 10 and a second bearing 20. The rotation axis is preferably the longitudinal axis of the impeller 3. Both bearings 10 and 20 are contact bearings. However, at least one of the bearings 10 and 20 can be a non-contact bearing, such as a magnetic or hydrodynamic bearing. The second bearing 20 is a pivot bearing having a spherical bearing surface that allows rotational and pivotal movement to some extent. The first bearing 10 is disposed within a support member 15 to stabilize the rotation of the impeller 3, and the support member 15 has at least one opening 16 for blood flow. Blades 4 are provided on the impeller 3 to transport blood as the impeller 3 rotates. The rotation of the impeller 3 is caused by an electric motor stator 8 magnetically coupled to the end portion 37 of the impeller 3. As will be understood by those skilled in the art, other suitable drive mechanisms are possible. The illustrated blood pump 1 is a mixed-type blood pump, and the primary flow direction is axial. Depending on the arrangement of the impeller 3, particularly the blades 4, it will be understood that the blood pump 1 may also be a pure axial-flow blood pump.

[0028] The impeller 3 is disposed on the downstream portion of the impeller 3 and includes a portion 33 that extends radially outward. The portion 33 may be called a yoke, flange portion, or end portion. In this embodiment, the portion 33 has an outer surface that extends at an angle of 45° with respect to the rotation axis 9. Other suitable angles, e.g., 30° to 60°, can be selected, or it may be a curved surface. The portion 33 may be formed integrally with the impeller 3 or separately, as shown in this embodiment. Two or more flush channels 30, preferably three, four, five, or six, although only one is shown in Figure 1, extend through the impeller 3, particularly through the portion 33, to allow flushing or rinsing of the pivot bearing 20 and the gap 31 between the impeller 3 and the stationary portion of the blood pump 1, particularly the pump casing 2 or the motor 8 which may be considered associated with the pump casing 2. At least one rinse channel 30 may also extend, at least partially, beyond part 33 into the main part of the impeller 3.

[0029] The flush channel 30 has a first opening 34 or inlet opening and a second opening 35 or outlet opening. The first opening 34 forms a fluid connection between the passage 7 and the flush channel 30, and the second opening 35 is fluidly connected to the gap 31. In particular, the second opening 35 is fluidly connected to the central bore or central opening 32 of section 33, which receives the second bearing 20. The gap 31 is fluidly connected to the passage 7 via a gap transition point 36, i.e., the position where the gap 31 is open to the passage 7.

[0030] The first opening 34 of the flush channel 30 is located in the downstream half of the impeller 3. In particular, the first opening 34 is located in the area of ​​the impeller 3 that is under high pressure generated by the rotation of the impeller 3 during the operation of the blood pump 1. Specifically, the first opening 34 may be near or in the area of ​​maximum pressure within the pump casing 2. The pressure increases due to the blades 4 and the deflection of the fluid from the axial direction to the radial direction, and decreases downstream of the blades 4. Therefore, by appropriately selecting the location of the first opening 34, which is near the downstream end of the impeller 3, the pressure at the gap transition point 36 is lower than that at the first opening 34 of the flush channel 30. This pressure distribution can be appropriately improved by selecting the shape of the blades 4, resulting in a flow direction from the first opening 34 through the flush channel 30 and gap 31 to the gap transition point 36. Alternatively, a further pressure drop at point 36 can be achieved by creating a local pressure drop in the vicinity of point 36 through the Venturi effect, for example, by providing a narrowing 53 in the passage 7 (see Figure 1A). In other words, blood flows forward through the flushing channel 30 toward the blood outlet 6 of the pump casing 2. During the operation of the blood pump 1, especially during phases with low rotational speeds below the design speed of the blood pump 1, flushing of the forward flow occurs at any rotational speed, effectively preventing blood coagulation.

[0031] Apart from flushing the pivot bearing 20 and the gap 31, blood flow through the flush channel 30 provides cooling for the pivot bearing 20. The pivot bearing 20 is located within the central opening 32 of section 33. Therefore, blood is transported towards the bearing 20 through the flush channel 30. The pivot bearing 20 can be effectively cooled and rinsed. The effect can be further improved by providing an auxiliary pump that actively supplies blood towards the bearing 20 through the flush channel 30, as will be described in detail later.

[0032] Referring now to Figure 3, one embodiment of the impeller 3 is shown. The impeller has blades 4 arranged around the body of the impeller 3. The blades 4 are sized and shaped to transport blood as the impeller 3 rotates in the rotational direction (indicated by the arrows in Figure 3). The impeller 3 has a downstream end 33, part 33 having at least one flush channel 30 having an inlet opening 34. As described above, the inlet opening 34 is located within the area of ​​the impeller 3. The impeller 3 ensures that under high pressure, blood flow through the flush channel 30 is directed from the first opening 34 or from the inlet opening to a second opening 35. In this embodiment, the inlet opening 34 is located on one forward side (also called the positive pressure side of the blade) of the blade 4 with respect to the rotational direction. In particular, the pressure is higher on the forward side of the blade 4 compared to the reverse side (also called the negative pressure side of the blade), which supports the inflow direction to the inlet opening 34 of the wash channel 30. In any case, the opening 34 is located on the reverse side of the blade 4. The reverse side of the blade 4 is the side where the pressure can be sufficiently high because the opening 34 is located in the portion 33 at the downstream end of the impeller 3.

[0033] Figures 4a-4b show various diagrams of one embodiment of part 33. In this embodiment, the flush channel 30 forms an auxiliary pump that delivers blood from the flush channel 30 through each of the first openings 34 to the second opening 35, and thus to the central opening 32 and the bearing 20, and further to the gap transition point 36 (see Figure 1). In this embodiment, the flush channel 30 extends linearly through the impeller 3 and is offset with respect to the rotation axis 9 (a bottom view of part 33, shown by the dashed line in Figure 4b). Since the flush channel 30 extends in a plane parallel to the rotation axis 9, the flush channel 30 extends along a direction having a tangential component. This arrangement directs the blood flow from the first opening 34 to the second opening 35. In this embodiment, two flush channels 30 are shown. However, it will be understood that three, four, or more flush channels can be provided similarly, and they may be arranged symmetrically around the rotation axis 9. In particular, as can be seen in Figure 4d, a cross-sectional view along line BB in Figure 4b, the wash channel 30 is inclined downstream. The second opening 35, which is downstream of the first opening 34, is closer to the rotation axis 9 than the first opening 34. The wash channel 30 opens to a central opening 32, which at least partially receives the second bearing 20, as shown in Figure 1.

[0034] Further embodiments of the impeller 3 having a flush channel 30 forming an auxiliary pump are shown in Figures 5a and 5b. According to the embodiment in Figure 5a, the first opening 34 is not circular. More precisely, a projection 38 extends into the first opening 34 to increase the amount of blood flowing through the first opening 34 into the flush channel. The projection 38 is positioned on the opposite side of the first opening 34 with respect to the direction of rotation. The resulting shape of the first opening 34 may be called kidney-shaped. This acts like an "airfoil" because when the impeller 3 rotates, a pull or suction is created, increasing the amount of blood entering the first opening 34, especially compared to embodiments without the projection 38 (such as the embodiment in Figure 3). The shape of the projection 38 can be selected according to the desired amount of blood to flow through the flush channel 30. The cross-section of the first opening 34 may be symmetrical or asymmetrical.

[0035] Instead of, or in addition to, the projection 38, a wing 39 may be provided as shown in Figure 5b. The wing 39 is positioned behind the first opening 34 with respect to the rotational direction and forms a pocket that captures a larger amount of blood as the impeller 3 rotates in the rotational direction. The wing 39 may have any size and shape suitable for increasing the amount of blood entering the first opening 34 compared to embodiments without the wing 39 (such as the embodiment in Figure 3). The same effect can be achieved by positioning the first opening 34 on a nose or projection extending radially from the impeller 3, so that the first opening 34 points in the rotational direction.

[0036] Referring next to Figures 6a and 6b, one embodiment of portion 33' having a flush channel 30' is shown. The direction of rotation is indicated by an arrow. As in the embodiment described above, the flush channel 30' has a first opening 34' and a second opening 35' facing the central opening 32'. The flush channel 30' forms part of an auxiliary pump, as described in relation to other embodiments, to push the blood flow toward the second bearing 20 in the direction from the first opening 34' to the second opening 35'. In this embodiment, the flush channel 30' is curved and extends around the axis of rotation 9 in a helical shape. The term “helical shape” will be understood to include any curved shape, whether it forms a regular helix or any other arbitrary curved shape having at least one tangential component. The flush channel 30' enters the impeller 3 at a small angle through the first opening, thereby forming the first opening 34', which has an elongated shape, due to the exposed portion of the flush channel 30'. This facilitates blood capture and helps increase the amount of blood entering the first opening 34' compared to a configuration in which the flush channel 30 extends to the surface of the impeller 3 at a larger angle, such as vertical or substantially vertical. The flush channel 30' extends in a curved shape toward the central opening 32' and exits the second opening 35' substantially radially. The blood is effectively supplied into the central opening 32' and therefore to the second bearing 20, rinsing and cooling the second bearing 20. As described in connection with Figure 1, the blood flow through the flush channel 30' effectively flushes the gap 31 between the rotating impeller 3 and the stationary pump casing 2. To further improve the performance of the auxiliary pump, the auxiliary pump may further provide grooves or blades formed on the surface of the impeller 3, particularly in the gap 31.

[0037] It should be understood that the auxiliary pump described above cannot overcome the centrifugal effect of a rotating channel of arbitrary shape, extending from a large diameter to a small diameter, without the assistance of centrifugal feeding in the gap 31.

[0038] The performance of the auxiliary pump can be further improved by the position of at least one of the first opening 34 and the gap transition point 36 relative to the rotating shaft 9, and especially relative to each other. As shown in Figure 7, the first opening has a first distance d1 to the rotating shaft 9, and the gap transition point 36 has a second distance d2 to the rotating shaft 9. The performance of the auxiliary pump can be improved when the first opening 34 is as close to the rotating shaft as possible, that is, when the distance d1 is as small as possible and the flush channel 30 extends only a short distance toward the rotating shaft 9. This reduces the centrifugal force that the flush flow flowing toward the rotating shaft must overcome. It is particularly advantageous when the first distance d1 is smaller than the second distance d2, and preferably d1 may be less than or equal to half of d2.

[0039] In another embodiment shown in Figure 8 in a cross-section perpendicular to the rotation axis 9, the impeller 3 includes a wash channel 40 with a first opening 41 and a second opening 42 disposed on the radially outer surface of the impeller 3. The first opening 41 is located on the forward side of one of the blades 4 with respect to the direction of rotation (indicated by the arrow in Figure 8), and the second opening 42 is located on the reverse side of the blade 4. This creates blood flow from the first opening 41 to the second opening 42. The wash channel 40 is in fluid communication with a central opening 32 to wash and cool the bearing 20. In the embodiment of Figure 9, a wash channel 43 is provided, similar to the embodiment of Figure 8, having a first opening 44 located on the forward side of one of the blades 4. However, the wash channel 43 extends through the blade 4 and exits through a second opening 45 located on the edge of the blade 4. This arrangement allows for the use of centrifugal force to direct the flush flow from the first opening 44 to the second opening 45. Figure 10 shows another embodiment similar to Figure 9. However, the first opening 44' of the flush channel 43' is located on the diagonal opposite side of the vane 4, through which the channel 43' extends and exits the second opening 45'. Thus, in this embodiment, the flush channel 43' passes diagonally or radially, rather than tangentially as in the embodiment of Figure 9, so that it touches all surfaces of the bearing 20.

[0040] An embodiment similar to that in Figure 8 is shown in Figure 11. The wash channel 40' has a first opening 41' located on the forward side of one of the blades 4 with respect to the rotational direction, and a second opening 42' located on the reverse side of the blade 4 (note that although the wash channel 40' is shown in a cross-sectional view in Figure 11, it does not extend within the plane of the cross-section, but is similar to the cross-section shown in Figure 8). The wash channel 40' extends downward from the blade 4. However, in the embodiment of Figure 11, the wash channel 40' does not extend within a plane perpendicular to the longitudinal axis 9, and the second opening 42' is located downstream of the first opening 41'. Therefore, the second opening 42' is also located radially outward from the first opening 41'. This configuration allows the flush flow to be increased by the centrifugal force in the outlet section of the flush channel 40' leading to the second opening 42'. Additionally, the flush flow is improved by the pressure difference between the first opening 41' and the second opening 42' within the passage 7.

[0041] It will be understood that at least one of the flush channels 40, 40', 43, and 43' described in relation to Figures 8-11 may be provided instead of, or in addition to, the flush channels 30 and 30' described above. It should also be understood that channels 40, 40', 43, and 43' are in fluid communication with the central opening 32 and gap 31, thereby enabling the same type of overall flush flow as described above.

[0042] A preferred embodiment is described in the following paragraphs.

[0043] 1. A pump casing 2 having a blood flow inlet 5 and a blood flow outlet 6 connected by a passage 7, An impeller 3 is disposed within the pump casing 2 so as to be rotatable about a rotation axis 9, and comprises blades 4 whose size and shape are determined to transport blood along the passage 7 from the blood inlet 5 to the blood outlet 6, and is rotatably supported within the pump casing 2 by at least one bearing 10, 20. The surface of the impeller 3 faces the surface of the pump casing 2, which is separated from the surface of the impeller 3 by a gap 31, and the gap 31 is fluidly connected to the passage 7 at the gap transition point 36. At least one flush channel 30 extends through the impeller 3 and is fluidly connected to the passage 7 through a first opening 34 and to the gap 31 through a second opening 35. The blood pump 1 is positioned in the area of ​​the impeller 3 such that the first opening 34 of the flush channel 30 is under a pressure higher than the gap transition point 36 during the operation of the blood pump 1, causing blood flow from the first opening 34 through the flush channel 30 and the gap 31 to reach the gap transition point 36.

[0044] 2. A blood pump according to paragraph 1, wherein the first opening 34 of the flush channel 30 is located on the downstream half of the impeller 3.

[0045] 3. A Paragraph 1 or 2 blood pump in which the first opening 34 of the flush channel 30 is located in a region of the impeller 3 where the pressure is higher than the intermediate pressure in the pressure distribution along the length of the passage 7 on which the impeller 3 is placed, during the operation of the blood pump 1.

[0046] 4. One of the blood pumps from paragraphs 1 to 3, wherein the first opening 34 of the flush channel 30 is located in the area of ​​the impeller 3 where the pressure is substantially the maximum pressure relative to the pressure distribution along the length of the passage 7 on which the impeller 3 is mounted during the operation of the blood pump 1.

[0047] 5. One of the blood pumps described in paragraphs 1 to 4, wherein the blood flow from the first opening 34 through the wash channel 30 and gap 31 to the gap transition point 36 is directed toward the blood flow outlet 6 of the pump casing 2.

[0048] 6. A blood pump according to any one of paragraphs 1 to 5, wherein the impeller 3 has a downstream portion 33 extending radially outward, and a first opening 34 of a flush channel 30 is disposed in the portion 33.

[0049] 7. The blood pump of paragraph 6, wherein the portion 33 is conically tapered, extending radially outward in the downstream direction.

[0050] 8. A blood pump of paragraph 6 or 7, in which the blades 4 of the impeller 3 extend over the portion 33.

[0051] 9. A blood pump, one of paragraphs 6 to 8, in which part 33 is formed integrally with or separately from the impeller 3.

[0052] 10. A blood pump, any one of paragraphs 1 to 8, wherein a flush channel 33 is operationally associated with an auxiliary pump that supplies blood from a first opening 34 through a flush channel 30 toward a gap transition point 36, and the auxiliary pump is at least partially formed by the at least one flush channel 30 extending through the impeller 3 in a direction having at least one tangential component.

[0053] 11. A blood pump from any one of paragraphs 1 to 10, wherein the flush channel 30 extends linearly through the impeller 3 and is offset with respect to the rotation axis 9.

[0054] 12. A blood pump of paragraph 11, in which the wash channel 30 extends in a plane parallel to the axis of rotation 9.

[0055] 13. A blood pump, one of paragraphs 1 to 10, wherein the flush channel 30 is curved and extends from the first opening 34 in a direction that rotates around the axis of rotation 9.

[0056] 14. A blood pump, one of paragraphs 1 to 13, wherein the flush channel 30 extends from the first opening 34 at an angle to the surface of the impeller 3 in a circumferential direction opposite to the direction of rotation.

[0057] 15. The blood pump of paragraph 14, wherein the angle is less than 20°, preferably less than 15°, and more preferably less than 10°.

[0058] 16. A blood pump of paragraph 14 or 15, wherein the flush channel 30 extends from the first opening 34 substantially tangentially to the surface of the impeller 3.

[0059] 17. Any one of the blood pumps described in paragraphs 1 to 16, wherein the distance between the second opening 35 and the rotating shaft 9 is less than or equal to the distance between the first opening 34 and the rotating shaft 9.

[0060] 18. Any one of the blood pumps described in paragraphs 1 to 17, wherein the distance between the rotating shaft 9 and the first opening 34 is less than 50%, preferably less than 40%, and more preferably less than 30% of the distance between the rotating shaft 9 and the gap transition point 36.

[0061] 19. A blood pump according to any one of paragraphs 1 to 18, wherein the impeller 3 extends along the rotating shaft 9 and has a central opening 32 that at least partially receives a bearing 20, and a second opening 35 is fluidly connected to the central opening 32.

[0062] 20. A blood pump, one of the inventions described in paragraphs 1 to 19, wherein the flush channel 30 at the second opening 35 is oriented substantially radially toward the axis of rotation 9.

[0063] 21. A blood pump according to any one of paragraphs 1 to 20, wherein the first opening 34 of the wash channel 30 is located adjacent to one of the blades 4 of the impeller 3 on the forward side of the blades 4 with respect to the rotational direction.

[0064] 22. One of the blood pumps from paragraphs 1 to 21, wherein the cross-section of the first opening 34 is circular.

[0065] 23. One of the blood pumps from paragraphs 1 to 21, wherein the cross-section of the first opening 34 is non-circular.

[0066] 24. Any one of paragraphs 1 to 23, wherein the first opening 34 is formed by the end portion of the wash channel 30, which is at least partially exposed by the wash channel 30 being inclined with respect to the surface of the impeller 3.

[0067] 25. One of the blood pumps from paragraphs 1 to 24, wherein the projection 38 extends into a first opening 34 of the flush channel 30 and is sized and shaped to increase blood flow entering the flush channel 30 through the first opening 34.

[0068] 26. A blood pump according to any one of paragraphs 1 to 25, wherein the impeller 3 comprises at least one wing 39 extending radially therefrom, adjacent to the first opening 34 of the wash channel 30 and positioned posterior to it in the direction of rotation.

[0069] 27. A blood pump of paragraph 26, with a wing 39 extending over the first opening 34 of the wash channel 30 and opening in a rotational direction to allow blood to enter the first opening 34.

[0070] 28. A blood pump according to any one of paragraphs 1 to 25, wherein the impeller 3 has a projection extending radially therefrom, the projection having a first opening 34 such that the cross section of the first opening 34 extends at a certain angle with respect to the surface of the impeller 3 and is open in the rotational direction, the angle preferably greater than 45°, more preferably 90°.

[0071] 29. A blood pump according to any one of paragraphs 1 to 28, comprising two or more flush channels 30 arranged symmetrically with respect to a rotation axis 9.

[0072] 30. A blood pump according to paragraph 10, and any one of paragraphs 1 to 9 and 11 to 29, wherein the auxiliary pump comprises grooves or blades formed on the surface of the impeller 3.

[0073] 31. A blood pump according to any one of paragraphs 1 to 30, wherein a first opening 41 is located on the forward side of the vane 4, a second opening 42 is located on the reverse side of the vane 4, and a flush channel 40 extends below the vane 4.

[0074] 32. A blood pump according to any one of paragraphs 1 to 31, wherein a flush channel 43 extends within the vane 4, a first opening 44 is located on the forward side of the vane 4, and a second opening 45 is located on the vane 4, particularly on the radial outer edge of the vane 4.

[0075] 33. A blood pump from any one of paragraphs 1 to 32, wherein bearing 20 is a pivot bearing.

[0076] 34. Pump 1 is one of the blood pumps described in paragraphs 1 through 33, which is an axial flow blood pump, a centrifugal blood pump, or a mixed blood pump.

Claims

1. A pump casing (2) having a blood inlet (5) and a blood outlet (6) connected by a passage (7), An impeller (3) is disposed within the pump casing (2) so as to be rotatable about a rotation axis (9), and comprises blades (4) of a size and shape determined to transport blood along the passage (7) from the blood inlet (5) to the blood outlet (6), and is rotatably supported within the pump casing (2) by at least one bearing (10, 20), The surface of the impeller (3) faces the surface of the pump casing (2) spaced apart from the surface of the impeller (3) via a gap (31), and the gap (31) is fluidly connected to the passage (7) at a gap transition point (36). At least one flush channel (43; 43') extends through the impeller (3) and is fluidly connected to the passage (7) through a first opening (44; 44') and to the gap (31) through a second opening (35), The first opening (44;44') of the flushing channel (43;43') is positioned in the area of ​​the impeller (3) such that, during the operation of the blood pump (1), it is under a pressure higher than the gap transition point (36) and directs blood flow from the first opening (44;44') through the flushing channel (43;43') and the gap (31) to the gap transition point (36), (a) The rinse channel (43) extends within the blade (4), the first opening (44) is located on the forward side with respect to the rotation axis (9) in one of the blades (4), and the third opening (45) of the rinse channel (43) is located within the blade (4), or (b) A blood pump (1) having any of the following configurations: the flush channel (43') extends into the vane (4), the first opening (44') is located on the diagonally opposite side of the vane (4), the flush channel (43') extends through the first opening (44'), and the third opening (45') of the flush channel (43') is located inside the vane (4).

2. A blood pump according to claim 1, characterized in that the first opening (44; 44') of the wash channel (43; 43') is located on the downstream half of the impeller (3).

3. A blood pump according to claim 1 or 2, characterized in that the first opening (44; 44') of the wash channel (43; 43') is located in a region of the impeller (3) where the pressure is higher than the intermediate pressure in the pressure distribution along the length of the passage (7) on which the impeller (3) is placed, during operation of the blood pump (1).

4. A blood pump according to any one of claims 1 to 3, characterized in that the blood flow from the first opening (44; 44') through the wash channel (43; 43') and the gap (31) to the gap transition point (36) is in the direction toward the blood outlet (6) of the pump casing (2).

5. A blood pump according to any one of claims 1 to 4, wherein the impeller (3) has a portion (33) that extends radially outward downstream with respect to the rotation axis, and the first opening (44; 44') of the wash channel (43; 43') is disposed in the portion (33).

6. A blood pump according to any one of claims 1 to 5, wherein the flushing channels (43; 43') are operationally associated with an auxiliary pump that supplies blood from the first opening (44; 44') through the flushing channels (43; 43') toward the gap transition point (36), and the auxiliary pump is at least partially formed by the at least one flushing channel (43; 43') extending through the impeller (3) in a direction having at least one tangential component.

7. A blood pump according to any one of claims 1 to 6, wherein the impeller (3) has a central opening (32) that extends along the rotating shaft (9) and at least partially receives the bearing (20), and the second opening (35) is fluidly connected to the central opening (32).

8. A blood pump according to any one of claims 1 to 7, characterized in that the flushing channels (43; 43') in the second opening (35) are substantially directed toward the rotation axis (9) in the radial direction.

9. A blood pump according to any one of claims 1 to 8, characterized in that the first opening (44) of the wash channel (43) is disposed adjacent to one of the blades (4) of the impeller (3).

10. A blood pump according to any one of claims 1 to 9, characterized in that the cross-section of the first opening (44; 44') is circular or non-circular.

11. A blood pump according to any one of claims 1 to 10, characterized in that the first opening (44; 44') is formed by the end portion of the wash channel (43; 43') which is at least partially exposed by the wash channel (43; 43') being inclined with respect to the surface of the impeller (3).

12. A blood pump according to any one of claims 1 to 11, wherein the projection (38) extends into the first opening (44;44') of the flushing channel (43;43') and is sized and shaped to increase blood flow entering the flushing channel (43;43') through the first opening (44;44').

13. A blood pump according to claim 3, characterized in that the pressure is the maximum pressure.

14. A blood pump according to claim 8, characterized in that the distance between the rotating shaft (9) and the first opening (44; 44') is less than 50% of the distance between the rotating shaft (9) and the gap transition point (36).

15. A blood pump according to claim 8, characterized in that the distance between the rotating shaft (9) and the first opening (44; 44') is less than 40% of the distance between the rotating shaft (9) and the gap transition point (36).

16. A blood pump according to claim 8, characterized in that the distance between the rotating shaft (9) and the first opening (44; 44') is less than 30% of the distance between the rotating shaft (9) and the gap transition point (36).

17. A blood pump according to Claim 1, characterized in that the third opening (45; 45') of the wash channel (43; 43') is disposed on the radial outer edge of the vane (4).

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