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 that is implanted in a patient to assist the patient's heart. In particular, the blood pump may be used as a "bridge to recovery" device, where the blood pump provides temporary assistance until the patient's heart has fully recovered.

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

[0003] The impeller is supported in the pump casing by at least one bearing, which may be of different types depending on the intended use of the blood pump, for example, whether the blood pump is intended for short-term (hours or days) use only or for long-term (weeks or years) use only. Various bearings are known, such as contact bearings and non-contact bearings. In non-contact bearings, the bearing surfaces do not contact each other, for example, in the case of magnetic bearings, where the bearing surfaces are "levitated" by repelling magnetic forces. In general, contact bearings may include all types of bearings, where the bearing surfaces may be at least partially in contact at any time during the operation of the pump (i.e., constantly or intermittently), such as, for example, plain bearings, pivot bearings, hydrodynamic bearings, hydrostatic bearings, ball bearings, etc., or any combination thereof. In particular, contact bearings may be "blood-immersed bearings" where the bearing surfaces have blood contact. Contact bearings may heat up during use and are prone to mechanical wear due to contact between the rotating and stationary bearing surfaces during the operation of the pump. It is desirable to provide a cooling fluid for the bearings, such as the blood itself. In non-contact bearings, the bearing surfaces have no physical contact and are separated by gaps that are in fluid communication with passages or other fluid supplies. Similarly, other gaps between the impeller and the pump casing should be flushed to avoid blood clotting and clogging, for example at the downstream front face of the impeller.

[0004] An arrangement for rinsing gaps or bearing surfaces in a blood pump is disclosed, for example, in US Patent Publication No. 2011 / 0238172 A1. The washout channel extends through the impeller and is in fluid communication with the passageway and the gap through the first and second openings. The pressure distribution in the pump casing causes blood flow through the gap and the washout channel when the pressure increases downstream along the impeller, and blood enters the gap at the downstream end of the impeller and flows through the washout channel towards the area of ​​the passageway at low pressure. This washout flow has the disadvantage of being dependent on the rotational speed of the impeller, by which a pressure difference must be created to cause blood flow. Other forces, such as centrifugal forces and reaction forces due to the reverse direction of the washout flow, must also be overcome. In another embodiment disclosed in U.S. Patent Publication No. 2011 / 0238172 A1, in which the impeller is supported within the pump casing by hydrodynamic bearings, the inlet opening of the wash channel is disposed at the upstream end of the impeller, and auxiliary vanes at the downstream end of the impeller are provided to effect wash flow through the wash channel and gap in a direction from the low pressure area to the high pressure area. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore a main object of the present invention to provide a blood pump in which stagnation of the blood flow and blood clotting and clogging in the gaps between the rotating and stationary parts of the blood pump, in particular between the bearings or the impeller and the stationary and rotating parts of the pump casing, are effectively avoided independent of the rotational speed or operating conditions of the pump. It is a further object of the present invention to provide a blood pump in which the gaps can be effectively flushed. It is yet another object of the present invention to provide a blood pump in which effective cooling of the contact bearings is possible. [Means for solving the problem]

[0006] The main object is achieved according to the invention by a blood pump with the features of the independent claim 1. Preferred embodiments and further developments of the invention are specified in the claims dependent on the independent claim.

[0007] Like known blood pumps, the blood pump according to the 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 stationary parts of the blood pump. An impeller or rotor is arranged in said pump casing rotatably about an axis of rotation, which may be the longitudinal axis of the impeller, the impeller comprising vanes sized and shaped to transport blood along the passage from the blood inlet to the blood outlet. At least one bearing is provided for rotatably supporting the impeller. A surface of the impeller faces a surface of the pump casing spaced from said surface of the impeller by a gap, which is in fluid communication with the passage at a gap transition point. To allow for flushing of the gap, at least one flushing channel extends through the impeller and is in fluid communication with the passage via a first opening and with the gap via a second opening.

[0008] In contrast to known blood pumps, the first opening of the washout channel is located in a region of the impeller that is under a higher pressure during operation of the pump than the gap transition point, forcing the blood flow from the first opening through the washout channel and the gap to the gap transition point. In other words, since the first opening of the washout channel, i.e. the inlet opening of the washout channel, is in a high pressure region of the impeller and the gap transition point is, for example, downstream of the impeller where the pressure is lower, the washout flow is directed in a "forward" direction, i.e. towards the blood outlet of the pump casing. Thus, by exploiting this pressure difference that occurs during operation of the blood pump, in particular the local pressure gradient in the washout channel, a forward flow washout is created. This has the advantage that the required pressure difference is always present during operation of the pump, independent of the rotation speed and operating conditions (e.g. preload, afterload, magnitude of the initial forward flow), especially at the beginning of operation when the impeller starts to rotate and the rotation speed is low, especially below the design speed of the blood pump. In contrast, in known blood pumps in which the flush flow is directed in the "reverse" direction, a pressure difference must be built up, which takes a certain amount of time during which the flush flow may be slow or stagnate. This leads to blood clotting and clogging in the gap or in the flush channel, or both. Furthermore, the reverse flow must overcome forces caused by the main direction of flow, which may also lead to stagnation of the flush flow and, as a consequence, to blood clotting and clogging. According to the invention, the flush flow is in the "forward" direction throughout the entire operating time of the blood pump, and in particular takes advantage of the pressure distribution in the pump casing during the operation of the pump. This flow can be further increased by an auxiliary pump, as will be described in more detail below. However, it will be understood that such an auxiliary pump is not essential for the functionality of the invention.

[0009] In a preferred embodiment, the first opening of the washout channel may be arranged in the downstream half of the impeller. During operation of the pump, pressure increases along the length of the impeller, in particular in the region where the impeller vanes are arranged. Thus, in the downstream half of the impeller, a higher pressure exists than in the upstream half of the impeller. According to the invention, since a high pressure at the first opening of the washout channel is required, more particularly above the clearance transition point, it is preferred to arrange the first opening in the downstream half of the impeller. More preferably, the first opening may be arranged in the downstream third, downstream quarter or downstream fifth of the impeller. In particular, it is advantageous to arrange the first opening as close as possible to the downstream end of the impeller, for example within the last 10% of the length of the impeller in the downstream direction.

[0010] Regarding the pressure distribution, the first opening of the flushing channel is preferably adapted to the pressure distribution along the length of the passage in which the impeller sits during operation of the pump. The median The impeller is disposed in a region where the pressure is greater than the intermediate pressure, more preferably where the pressure is substantially the maximum pressure. The high pressure differential between the first opening of the wash channel and the gap transition point improves wash flow from the first opening of the wash channel to the gap transition point.

[0011] To further improve the washout flow, the vanes may be specifically shaped to assist the above-mentioned pressure distribution within the pump, particularly to create a high pressure at the first opening of the washout channel. The washout flow may be further improved by providing an auxiliary pump operatively associated with the washout channel, which pumps blood through the washout channel towards the gap transition point. The auxiliary pump may be at least partially formed by said at least one washout channel in that the washout channel extends through the impeller along a direction having at least one tangential component. In other words, the second pump may be at least partially formed by said at least one washout channel, which may be specifically sized, shaped and positioned to pump blood through the washout channel towards the bearing. The washout flow may thus be referred to as a dynamic washout flow.

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

[0013] In one embodiment, the wash channel may extend straight through the impeller and may 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 with a straight wash channel that is oblique to the axis of rotation, i.e. does not intersect with the axis of rotation, it is possible to provide a dynamic wash flow through the wash channel.

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

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

[0016] In one embodiment, the distance between the second opening and the axis of rotation is equal to or less than the distance between the first opening and the axis of rotation. In other words, in the downstream direction, the flushing channel extends in a direction towards the axis of rotation. Preferably, the distance between the first opening and the axis of rotation is as short as possible in order to reduce the centrifugal forces that the flushing flow in the flushing 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 preferred that the distance between the axis of rotation and the first opening is significantly shorter than the distance between the axis of rotation and the gap transition point, for example less than half (50%), less than 40%, or even less than 30%. This configuration allows for an improvement in centrifugal blood pumps over axial or mixed blood pumps, i.e. the distance between the first opening and the gap transition point can be increased.

[0017] The impeller may include a central opening extending along the axis of rotation and receiving the bearing, the second opening being in fluid communication with the central opening, and the wash channels may be oriented substantially radially at the second opening and towards the axis of rotation, thereby improving rinsing of the bearing and thereby cooling of the bearing.

[0018] Preferably, the first opening of the wash channel is disposed adjacent to one of the vanes of the impeller, on the forward side of the vane with respect to the direction of rotation (commonly referred to as the pressure side of the vane). In this area, the pressure is higher than in particular in the reverse side of the vane (commonly referred to as the suction side of the vane), thereby improving the dynamic wash flow through the wash channel. In one embodiment, the first opening may be disposed on the forward side of the vane and the second opening may be disposed on the reverse side of the vane, i.e. both openings are disposed on the radially outer surface of the impeller and the wash channel is disposed on the downward (Base of the feather)and across the vane. In another embodiment, the washout channel may extend within the vane, such that the first opening is disposed on the forward side of the vane and the second opening is disposed in the vane, and in particular at the radially outer edge of the vane. It should be understood that the washout channel is in fluid communication with the area being washed out.

[0019] As described, the performance or output of the auxiliary pump can be improved by a particular configuration of the wash channel through the impeller, e.g., a straight or curved wash channel, which may extend at an angle relative to the surface of the impeller. The performance of the auxiliary pump can be further improved by the cross-section of the first opening of the wash channel. The cross-section of the first opening can be circular or non-circular. If the wash channel has a circular cross-section and extends at an angle relative 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 can be formed by an end portion of the wash channel that is at least partially exposed by the wash channel being inclined relative to the surface of the impeller. In other words, the first opening can be elongated at the surface of the impeller, which can further increase the amount of blood entering the wash channel during operation of the blood pump.

[0020] In another embodiment, the protrusion extends into the first opening of the flushing channel and is sized and shaped to increase blood flow through the first opening into the flushing channel, particularly compared to the cross section of the first opening without the protrusion. The shape of the first opening without the protrusion may be either circular or non-circular. The protrusion is disposed on the opposite side of the first opening relative to the direction of rotation, and therefore acts as an "airfoil" to promote blood flow into the first opening, thereby improving the performance of the auxiliary pump. Alternatively or additionally, the impeller may include wings extending radially therefrom and disposed adjacent to the first opening of the flushing channel and aft of the first opening relative to the direction of rotation. Preferably, the wings extend above the first opening of the flushing channel and are open in the direction of rotation to allow blood to enter the first opening. The wings form pockets that collect blood during rotation of the impeller and direct the collected blood into the first opening. To achieve a similar effect, the impeller may be provided with a nose or protrusion with the first opening such that the cross section of the first opening extends at an angle to the surface of the impeller, preferably an angle of more than 45°, more preferably an angle of 90°, and opens in the direction of rotation, thereby significantly increasing the amount of blood entering the flushing channel.

[0021] Preferably, the blood pump comprises two or more of the above-mentioned flushing channels, 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 flushing channels.

[0022] In addition to the size, shape and arrangement of the flush channel forming at least a portion of the secondary pump, the secondary pump may further comprise grooves or vanes formed in the surface of the impeller, which may be disposed on the downstream front face of the impeller to assist blood flow through the flush channel towards the bearing.

[0023] In one embodiment, the impeller comprises: On the downstream side, Extending radially outward Department The auxiliary pump may have a portion, and the first opening of the washout channel is disposed in said portion. In particular, said portion has a conical taper radially outward in the downstream direction. The portion may be integrally formed with the impeller or may be formed separately. The performance of the auxiliary pump may be further improved by locating the first opening in a radially extending portion of the impeller such that it is oriented in a direction opposite to the main direction of blood flow through the passage. The first opening may thereby capture more blood and the performance of the auxiliary pump is improved. The vanes of the impeller may extend over said portion.

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

[0025] [Figure 1] 1 is a cross-sectional view of a blood pump according to the invention for extracardiac applications; [Figure 1A] 1 is a cross-sectional view of a blood pump according to the invention for extracardiac applications; [Diagram 2] 1 is a cross-sectional view of a blood pump according to the invention designed as a catheter pump; [Diagram 3] FIG. [Figure 4a] 1A-1D are various views of a portion of an impeller; [Figure 4b] 1A-1D are various views of a portion of an impeller; [Figure 4c] 1A-1D are various views of a portion of an impeller; [Figure 4d] 1A-1D are various views of a portion of an impeller; [Figure 5a] FIG. 13 illustrates another embodiment of the impeller. [Figure 5b] FIG. 13 illustrates another embodiment of the impeller. [Figure 6a]FIG. 13 illustrates another embodiment of a portion of an impeller. [Figure 6b] FIG. 13 illustrates another embodiment of a portion of an impeller. [Figure 7] FIG. 13 is a cross-sectional view of a portion of a blood pump according to another embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a portion of an impeller according to another embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a portion of an impeller according to another embodiment. [Figure 10] FIG. 13 is a cross-sectional view of a portion of an impeller according to yet another embodiment. [Figure 11] 11 is a cross-sectional view of a portion of a blood pump according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] With reference to FIG. 1, a cross-sectional view of a blood pump 1 is shown. The 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 the blood outlet 6 are connected to respective connectors (in particular the inflow from the heart and the outflow to the aorta). FIG. 2 shows an embodiment similar to FIG. 1, except that it is designed as a catheter pump 1'. The blood inlet 5' is at the end of a flexible catheter 50 placed through a heart valve, such as the aortic valve, and during use the blood outlet 6' is located on the side of the pump casing 2' and in a heart vessel, such as the aorta. The blood pump 1' is connected to a catheter 51, through which an electric wire 52 extends to drive the pump 1'. Both blood pumps 1 and 1' function in the same way. It will be understood that all the features described below are applicable to both embodiments.

[0027] Blood is conveyed along a passage 7 connecting the blood inlet 5 and the blood outlet 6. The impeller 3 is provided for conveying blood along the passage 7 and is rotatably mounted within the pump casing 2 about 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, 20 are contact type bearings. However, at least one of the bearings 10, 20 can be a non-contact type bearing, such as a magnetic or hydrodynamic bearing. The second bearing 20 is a pivot bearing with a spherical bearing surface that allows rotational movement as well as pivotal movement to a certain extent. The first bearing 10 is disposed within a support member 15 to stabilize the rotation of the impeller 3, the support member 15 having at least one opening 16 for the blood flow. Vanes 4 are provided on the impeller 3 to convey blood as it rotates. Rotation of the impeller 3 is caused by an electric motor stator 8 that is magnetically coupled to an end portion 37 of the impeller 3. As will be appreciated by those skilled in the art, other suitable drive mechanisms are possible. The illustrated blood pump 1 is a mixed type blood pump, with the main flow direction being axial. It will be appreciated that depending on the arrangement of the impeller 3, and in particular the blades 4, the blood pump 1 may also be a pure axial blood pump.

[0028] The impeller 3 comprises a portion 33 arranged at the downstream portion of the impeller 3 and extending radially outward. The portion 33 can be called a yoke, a flange portion or an end portion. In this embodiment, the portion 33 comprises an outer surface extending at an angle of 45° to the axis of rotation 9. Other suitable angles can be chosen, for example between 30° and 60°, or it can be a curved surface. The portion 33 can be formed integrally with the impeller 3 or separately as shown in this embodiment. At least one flushing channel 30, preferably two or more, such as three, four, five or six, flushing channels 30, only one of which is shown in FIG. 1, extend through the impeller 3, in particular 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, in particular the pump casing 2 or the motor 8, which may be considered as being associated with the pump casing 2. At least one wash channel 30 may also extend, at least partially, beyond portion 33 into the main portion 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 a central bore or central opening 32 of the portion 33, which receives the second bearing 20. The gap 31 is fluidly connected to the passage 7 through a gap transition point 36, i.e., the location where the gap 31 opens to the passage 7.

[0030] The first opening 34 of the wash channel 30 is arranged in the downstream half of the impeller 3. In particular, the first opening 34 is arranged in an area of ​​the impeller 3 that is under high pressure caused by the rotation of the impeller 3 during operation of the blood pump 1. In particular, the first opening 34 may be in an area close to or at the maximum pressure in the pump casing 2. The pressure increases due to the vanes 4 and the deflection of the fluid from the axial direction to the radial direction and decreases downstream of the vanes 4. Thus, by appropriate selection of the position 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 at the first opening 34 of the wash channel 30. This pressure distribution can be appropriately improved by selecting the shape of the vanes 4, resulting in a flow direction from the first opening 34 through the wash channel 30 and the 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 by the Venturi effect in the vicinity of point 36, for example by providing a constriction 53 (see FIG. 1A) in the passage 7. In other words, blood flows in a forward direction through the wash channel 30 towards the blood outlet 6 of the pump casing 2. During operation of the blood pump 1, wash out of the forward flow occurs at all rotational speeds, especially also during phases of low rotational speeds below the design speed of the blood pump 1, so that blood clotting can be effectively avoided.

[0031] Apart from flushing the pivot bearing 20 and the gap 31, the blood flow through the flush channel 30 also results in cooling of the pivot bearing 20. The pivot bearing 20 is located in the central opening 32 of the portion 33. Thus, blood is conveyed through the flush channel 30 towards the bearing 20. The pivot bearing 20 can be effectively cooled and rinsed. As will be described in more detail below, the effect can be further improved by providing an auxiliary pump that actively pumps blood through the flush channel 30 towards the bearing 20.

[0032] Referring now to FIG. 3, one embodiment of an impeller 3 is shown. The impeller has vanes 4 arranged around the body of the impeller 3. The vanes 4 are sized and shaped to transport blood as the impeller 3 rotates in the direction of rotation (indicated by the arrow in FIG. 3). The impeller 3 has a downstream end 33, which has at least one flush channel 30 with an inlet opening 34. As mentioned 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 the inlet opening to the second opening 35. In this embodiment, the inlet opening 34 is disposed on the forward side of one of the vanes 4 with respect to the direction of rotation (also referred to as the pressure side of the vane). In particular, the pressure is higher on the forward side compared to the reverse side of the vane 4 (also called the suction side of the vane), thereby favoring the inflow direction to the inlet opening 34 of the scrubbing channel 30. In any case, the opening 34 is disposed on the reverse side of the vane 4. The reverse side of the vane 4 is the side where the pressure may be high enough for the opening 34 to be disposed in the portion 33 at the downstream end of the impeller 3.

[0033] In Figures 4a-4b, various views of one embodiment of the portion 33 are shown. In this embodiment, the flushing channels 30 form an auxiliary pump that pumps blood from the flushing channels 30 through the respective first openings 34 to the second openings 35, and thus to the central opening 32 and the bearing 20, and further to the clearance transition point 36 (see Figure 1). In this embodiment, the flushing channels 30 extend in a straight line through the impeller 3 and are misaligned with respect to the axis of rotation 9 (indicated by the dashed line in Figure 4b, a bottom view of the portion 33). The flushing channels 30 extend in a plane parallel to the axis of rotation 9, so that the flushing channels 30 extend along a direction that has a tangential component. This arrangement directs the blood flow from the first openings 34 to the second openings 35. In this embodiment, two flushing channels 30 are shown. However, it will be understood that three, four or more flushing channels can be provided as well, and that they may be symmetrically arranged around the axis of rotation 9. As can be seen in particular in Fig. 4d, which is a cross-sectional view along line BB in Fig. 4b, the rinse channel 30 is inclined in the downstream direction: the second opening 35, which is downstream relative to the first opening 34, is closer to the axis of rotation 9 than the first opening 34. The rinse channel 30 opens into a central opening 32, which at least partially receives the second bearing 20, as shown in Fig. 1.

[0034] Further embodiments of the impeller 3 with a flushing channel 30 forming an auxiliary pump are shown in figures 5a and 5b. According to the embodiment of figure 5a, the first opening 34 is not circular. More precisely, a protrusion 38 extends into the first opening 34 in order to increase the amount of blood flowing through the first opening 34 into the flushing channel. The protrusion 38 is arranged 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. It acts like an "airfoil", since as the impeller 3 rotates a pull or suction is created, which increases the amount of blood entering the first opening 34, especially compared to an embodiment without the protrusion 38 (such as the embodiment of figure 3). The shape of the protrusion 38 can be selected according to the desired amount of blood to flow through the flushing channel 30. The cross section of the first opening 34 may be symmetrical or asymmetrical.

[0035] Instead of or in addition to the protrusions 38, wings 39 may be provided as shown in Figure 5b. The wings 39 are located behind the first opening 34 relative to the direction of rotation and form a pocket that captures more blood as the impeller 3 rotates in the direction of rotation. The wings 39 may have any size and shape suitable for increasing the amount of blood entering the first opening 34 compared to an embodiment without the wings 39 (such as the embodiment of Figure 3). The same effect can be achieved by locating the first opening 34 on a nose or protrusion extending radially from the impeller 3 and pointing in the direction of rotation.

[0036] 6a and 6b, an embodiment of a portion 33' having a flushing channel 30' is shown. The direction of rotation is indicated by the arrows. As in the above-mentioned embodiment, the flushing channel 30' has a first opening 34' and a second opening 35' facing a central opening 32'. The flushing channel 30' forms part of an auxiliary pump as described in connection with the other embodiments to push blood flow in the direction from the first opening 34' to the second opening 35' towards the second bearing 20. In this embodiment, the flushing channel 30' is curved and extends around the axis of rotation 9 in a helical shape. It will be understood that the term "helical shape" includes any curved shape, whether forming a regular helix or any other curved shape having at least one tangential component. The flushing channels 30' enter the impeller 3 at a first opening at a small angle, whereby the first opening 34' is formed by the exposed portion of the flushing channels 30' and has an elongated shape. This promotes blood capture and helps to increase the amount of blood entering the first opening 34', especially compared to a configuration in which the flushing channels 30 extend to the surface of the impeller 3 at a large angle, such as vertical or substantially vertical. The flushing channels 30' extend in a curved shape towards the central opening 32' and exit the second opening 35' in a substantially radial direction. The blood is effectively pumped into the central opening 32' and thus to the second bearing 20 for rinsing and cooling the second bearing 20. As explained in connection with FIG. 1, the blood flow through the flushing channels 30' effectively flushes the gap 31 between the rotating impeller 3 and the stationary pump casing 2. To further improve the performance of the backing pump, the backing pump may further comprise grooves or vanes 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 effects of a rotating channel of any shape extending from a large diameter to a small diameter without assistance from the centrifugal pumping action in the gap 31.

[0038] The performance of the auxiliary pump can be further improved by the location of at least one of the first opening 34 and the clearance transition point 36 relative to the axis of rotation 9, and particularly relative to each other. As shown in FIG. 7, the first opening is located at a first distance d 1 and the gap transition point 36 has a second distance d 2 The performance of the auxiliary pump is improved when the first opening 34 is as close as possible to the axis of rotation, i.e., the distance d 1 This can be improved if the first distance d is as small as possible and the flushing channel 30 extends only a small distance towards the axis of rotation 9. This reduces the centrifugal forces that the flushing flow has to overcome in the direction towards the axis of rotation. In particular, the first distance d 1 is the second distance d 2 It is advantageous if it is smaller than d 1 d 2 It may be less than half of the above.

[0039] In another embodiment, shown in a cross section perpendicular to the axis of rotation 9 in FIG. 8, the impeller 3 includes a wash channel 40 with a first opening 41 and a second opening 42 arranged on the radially outer surface of the impeller 3. The first opening 41 is arranged on the forward side of one of the vanes 4 with respect to the direction of rotation (indicated by the arrow in FIG. 8), and the second opening 42 is arranged on the reverse side of the vane 4. This results in a blood flow from the first opening 41 to the second opening 42. The wash channel 40 is in fluid communication with the central opening 32 to wash and cool the bearing 20. In the embodiment of FIG. 9, a wash channel 43 is provided, having a first opening 44 arranged on the forward side of one of the vanes 4, similar to the embodiment of FIG. 8. However, the wash channel 43 extends through the vane 4 and leaves a second opening 45 arranged at the edge of the vane 4. This arrangement makes it possible to use centrifugal forces to direct the wash 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 wash channel 43' is arranged on the diagonally opposite side of the vane 4 through which the channel 43' extends, where it exits at a second opening 45'. Thus, in this embodiment, the wash channel 43' touches all faces of the bearing 20, since it runs diagonally or radially, rather than tangentially as in the embodiment of Figure 9.

[0040] An embodiment similar to Figure 8 is shown in Figure 11. A wash channel 40' has a first opening 41' disposed on the forward side of one of the vanes 4 relative to the direction of rotation, and a second opening 42' disposed on the reverse side of the vane 4 (note that the wash channel 40' is shown in cross section in Figure 11, but does not extend in the plane of the cross section, but is similar to the cross section shown in Figure 8). The wash channel 40' extends below the vanes 4. (Base)11 , the flushing channel 40′ does not extend in one plane perpendicular to the longitudinal axis 9, but the second opening 42′ is arranged downstream of the first opening 41′. The second opening 42′ is therefore also arranged radially outward from the first opening 41′. This arrangement allows the flushing flow to be increased by centrifugal forces at the outlet section of the flushing channel 40′ leading to the second opening 42′. Also, the pressure difference between the first opening 41′ and the second opening 42′ in the passage 7 improves the flushing flow.

[0041] It will be appreciated that at least one of the flush channels 40, 40', 43, 43' described in connection with Figures 8-11 may be provided in place of or in addition to the flush channels 30, 30' described above. It will also be appreciated that the channels 40, 40', 43, 43' are in fluid communication with the central opening 32 and the gap 31, thereby allowing for an overall flush flow in the same manner as described above.

[0042] Preferred embodiments are described in the following paragraphs.

[0043] 1. A pump casing 2 having a blood inlet 5 and a blood outlet 6 connected by a passage 7; an impeller 3 disposed within said pump casing 2 for rotation about an axis of rotation 9, the impeller 3 having blades 4 sized and shaped to transport blood along a passage 7 from a blood inlet 5 to a blood outlet 6, the impeller 3 being rotatably supported within the pump casing 2 by at least one bearing 10, 20; a surface of the impeller 3 facing a surface of the pump casing 2 spaced from said surface of the impeller 3 by a gap 31, the gap 31 being in fluid communication with the passage 7 at a gap transition point 36; At least one flush channel 30 extends through the impeller 3 and is in fluid communication with the passage 7 via a first opening 34 and with the gap 31 via a second opening 35; A blood pump 1, in which a first opening 34 of the flushing channel 30 is positioned in the area of ​​the impeller 3 such that during operation of the blood pump 1, the first opening 34 is under a higher pressure than the gap transition point 36, causing blood flow from the first opening 34 through the flushing channel 30 and the gap 31 to the gap transition point 36.

[0044] 2. The blood pump of paragraph 1, wherein the first opening 34 of the flush channel 30 is disposed in the downstream half of the impeller 3.

[0045] 3. The first opening 34 of the flush channel 30 is adapted to the pressure distribution along the length of the passage 7 in which the impeller 3 sits during operation of the blood pump 1. The median 3. The blood pump of paragraph 1 or 2, wherein the impeller 3 is disposed in a region where the pressure is higher than the pressure.

[0046] 4. A blood pump of any one of paragraphs 1 to 3, wherein the first opening 34 of the flushing channel 30 is disposed in an area of ​​the impeller 3 where, during operation of the blood pump 1, the pressure is substantially maximum pressure relative to the pressure distribution along the length of the passage 7 in which the impeller 3 is placed.

[0047] 5. The blood pump of any one of paragraphs 1 to 4, wherein blood flow from the first opening 34 through the flush channel 30 and the gap 31 to the gap transition point 36 is in a direction toward the blood flow outlet 6 of the pump casing 2.

[0048] 6. Impeller 3, On the downstream side, Extending radially outward Department 6. The blood pump of any one of paragraphs 1 to 5, having a portion 33, the first opening 34 of the flush channel 30 being disposed in said portion 33.

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

[0050] 8. The blood pump of paragraph 6 or 7, wherein the blades 4 of the impeller 3 extend over said portion 33.

[0051] 9. The blood pump of any one of paragraphs 6 to 8, wherein part 33 is integrally formed with impeller 3 or formed separately.

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

[0053] 11. The blood pump of any one of paragraphs 1 to 10, wherein the flush channel 30 extends in a straight line through the impeller 3 and is offset relative to the axis of rotation 9.

[0054] 12. The blood pump of paragraph 11, wherein the flush channel 30 extends in a plane parallel to the axis of rotation 9.

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

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

[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. The 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. The blood pump of any one of paragraphs 1 to 16, wherein the distance between the second opening 35 and the rotation axis 9 is less than or equal to the distance between the first opening 34 and the rotation axis 9.

[0060] 18. The blood pump of any one of paragraphs 1 to 17, wherein the distance between the rotation axis 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 rotation axis 9 and the gap transition point 36.

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

[0062] 20. The blood pump of any one of 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. The blood pump of any one of paragraphs 1 to 20, wherein the first opening 34 of the flush channel 30 is disposed adjacent to one of the blades 4 of the impeller 3, on the forward side of the blade 4 relative to the direction of rotation.

[0064] 22. The blood pump of any one of paragraphs 1 to 21, wherein the cross section of the first opening 34 is circular.

[0065] 23. The blood pump of any one of paragraphs 1 to 21, wherein the cross-section of the first opening 34 is non-circular.

[0066] 24. The blood pump of any one of paragraphs 1 to 23, wherein the first opening 34 is formed by an end portion of the flush channel 30 that is at least partially exposed by the flush channel 30 being inclined relative to the surface of the impeller 3.

[0067] 25. The blood pump of any one of paragraphs 1 to 24, wherein the protrusions 38 extend into the first openings 34 of the flush channel 30 and are sized and shaped to increase blood flow through the first openings 34 and into the flush channel 30.

[0068] 26. The blood pump of any one of paragraphs 1 to 25, wherein the impeller 3 has at least one wing 39 extending radially therefrom and disposed adjacent to and rearwardly of the first opening 34 of the flushing channel 30 in the direction of rotation.

[0069] 27. The blood pump of paragraph 26, wherein the wing 39 extends over the first opening 34 of the flush channel 30 and is rotationally open to allow blood to enter the first opening 34.

[0070] 28. A blood pump of any one of paragraphs 1 to 25, wherein the impeller 3 has a protrusion extending radially therefrom, the protrusion having a first opening 34 such that a cross-section of the first opening 34 extends at an angle to the surface of the impeller 3 and is open in the direction of rotation, the angle preferably being 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 the axis of rotation 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 has grooves or vanes formed on the surface of the impeller 3.

[0073] 31. A first opening 41 is disposed on the forward side of the blade 4, a second opening 42 is disposed on the reverse side of the blade 4, and a flushing channel 40 is disposed below the blade 4. (At the base) 31. The blood pump of any one of paragraphs 1 to 30,

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

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

[0076] 34. The blood pump of any one of paragraphs 1 to 33, wherein pump 1 is an axial blood pump, a centrifugal blood pump, or a mixed type blood pump.

Claims

1. 1. A blood pump comprising: a pump casing (2) having a blood flow inlet (5) and a blood flow outlet (6) connected by a passage (7); an impeller (3) disposed within said pump casing (2) so as to be rotatable about an axis of rotation (9), said impeller (3) having blades (4) sized and shaped to transport blood along said passageway (7) from said blood inlet (5) to said blood outlet (6), said impeller (3) being rotatably supported within said pump casing (2) by at least one bearing (10, 20); a surface of the impeller (3) facing a surface of the pump casing (2) spaced from the surface of the impeller (3) by a gap (31), the gap (31) being in fluid communication with the passage (7) at a gap transition point (36); at least one flush channel (40, 40') extends through said impeller (3) and is fluidly connected to said passage (7) via a first opening (41, 41') and to said gap (31) via a second opening (35); the first opening (41, 41') of the flush channel (40, 40') is located in the region of the impeller (3) such that during operation of the blood pump (1) it is under a higher pressure than the gap transition point (36) to allow blood flow from the first opening (41, 41') through the flush channel (40, 40') and the gap (31) to the gap transition point (36); The blood pump (1) is characterized in that the first opening (41, 41') is disposed on a forward side of one of the blades (4), and the flushing channel (40, 40') extends at the root of one of the blades (4) to a third opening (42, 42') disposed on a reverse side of one of the blades (4).

2. 2. Blood pump according to claim 1, characterized in that the first opening (41, 41') of the flushing channel (40, 40') is arranged in the downstream half of the impeller (3).

3. 3. The blood pump according to claim 1 or 2, characterized in that the first opening (41, 41') of the flushing channel (40, 40') is arranged in a region of the impeller (3) which, during operation of the blood pump (1), has a pressure higher than the median pressure in the pressure distribution along the length of the passage (7) in which the impeller (3) is located.

4. 4. The blood pump according to claim 1, wherein the blood flow from the first opening (41, 41') through the wash channel (40, 40') and the gap (31) to the gap transition point (36) is in a direction towards the blood flow outlet (6) of the pump casing (2).

5. 5. The blood pump according to claim 1, wherein the impeller (3) has a portion (33) on the downstream side that extends radially outward with respect to the axis of rotation (9), and the first opening (41, 41') of the flushing channel (40, 40') is arranged in said portion (33).

6. 6. The blood pump according to claim 1, wherein the flush channel (40, 40') is operatively associated with an auxiliary pump that pumps blood from the first opening (41, 41') through the flush channel (40, 40') towards the gap transition point (36), the auxiliary pump being at least partially defined by the at least one flush channel (40, 40') extending through the impeller (3) along a direction having at least one tangential component.

7. 7. A blood pump according to claim 1, wherein the impeller (3) has a central opening (32) extending along the axis of rotation (9) and at least partially receiving the bearing (20), and the second opening (35) is fluidly connected to the central opening (32).

8. 8. The blood pump according to claim 1, wherein the flushing channels (40, 40') in the second opening (35) are oriented substantially radially towards the axis of rotation (9).

9. 9. The blood pump according to claim 1, wherein the first opening (41, 41') of the flushing channel (40, 40') is arranged adjacent to one of the vanes (4) of the impeller (3).

10. 10. Blood pump according to any one of the preceding claims, characterized in that the cross section of the first opening (41, 41') is circular or non-circular.

11. 11. The blood pump according to claim 1, wherein the first opening (41, 41') is formed by an end portion of the flush channel (40, 40') that is at least partially exposed by virtue of the flush channel (40, 40') being inclined relative to the surface of the impeller (3).

12. 12. The blood pump of claim 1, wherein a protrusion (38) extends into the first opening (41, 41') of the flush channel (40, 40') and is sized and shaped to increase blood flow through the first opening (41, 41') into the flush channel (40, 40').

13. 4. The blood pump of claim 3, wherein said pressure is a maximum pressure.

14. 9. The blood pump according to claim 8, characterized in that the distance between the axis of rotation (9) and the first opening (41, 41') is less than 50% of the distance between the axis of rotation (9) and the clearance transition point (36).

15. 9. The blood pump according to claim 8, characterized in that the distance between the axis of rotation (9) and the first opening (41, 41') is less than 40% of the distance between the axis of rotation (9) and the clearance transition point (36).

16. 9. The blood pump according to claim 8, wherein the distance between the axis of rotation (9) and the first opening (41, 41') is less than 30% of the distance between the axis of rotation (9) and the clearance transition point (36).

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