Blood pump

Abstract

To provide a blood pump that enables effective cooling and flushing of a bearing that rotatably supports an impeller of a blood pump.SOLUTION: A blood pump 1 includes a pump casing 2, and an impeller 3 disposed in the pump casing 2, which is rotatably supported by a bearing 60 in the pump casing 2 so as to rotate around a rotation shaft. The impeller 3 includes blades 31 and 32. The bearing 60 is coupled to the pump casing 2 and includes at least one fixed bearing part 4 having a fixed bearing surface 61 directed to the radial outer side. The bearing 60 further includes a rotary bearing surface 62 that interacts with the fixed bearing surface 61 and forms the bearing 60. The rotary bearing surface 61 is directed to the radial inner side and is formed at a radial inner side edge part 50 in which the blade 32 is exposed. The blade 32 is designed so as to draw in deposited blood on the fixed bearing surface 61 in the direction of the radial outer side.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to blood pumps, and more particularly to intravascular blood pumps for supporting blood flow within a patient's blood vessels. [Background technology]

[0002] Different types of blood pumps are known, such as axial, centrifugal or mixed blood pumps, where blood flow is induced by both axial and radial forces. Intravascular blood pumps are inserted into a patient's blood vessel, such as the aorta, by a catheter. Blood pumps typically include a pump casing having a blood flow inlet and a blood flow outlet. An impeller or rotor is supported within the pump casing for rotation about a rotation axis to generate blood flow from the blood flow inlet to the blood flow outlet, the impeller having one or more blades for transporting blood.

[0003] The impeller is typically supported in the pump casing by at least one bearing. Various bearings are known, such as contact and non-contact bearings. In general, contact bearings may include all types of bearings whose bearing surfaces are in at least partial contact during operation of the pump at all times (i.e., constantly or intermittently), such as plain bearings, pivot bearings, hydrostatic bearings, ball bearings, etc., or any combination thereof. In particular, contact bearings may be "blood-immersed bearings" whose bearing surfaces are in contact with blood. Contact bearings may be subject to heating during operation and mechanical wear due to contact of rotating and static bearing surfaces during operation of the pump. It is desirable to supply the bearings with a cooling fluid, such as blood itself.

[0004] An apparatus for flushing gaps or bearing surfaces in a blood pump is disclosed, for example, in US Patent No. 5,399,633. A flushing channel extends through the impeller and is in fluid communication with the main blood flow path and the bearing surfaces. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2011 / 0238172A1 Summary of the Invention [Means for solving the problem]

[0006] The present invention aims to provide a blood pump that allows for effective cooling and flushing of the bearings that rotatably support the blood pump impeller.

[0007] This object is achieved according to the invention by a blood pump having 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 1.

[0008] According to the invention, an impeller is rotatably supported in a pump casing by at least one bearing. The bearing comprises at least one fixed bearing part coupled to the pump casing and having a fixed bearing surface facing radially outward, the bearing further comprising a rotating shaft surface that interacts with the fixed bearing surface to form the bearing, the rotating bearing surface facing radially inward and formed on the exposed radially inner edge of at least one blade or on a bearing structure coupled to the exposed radially inner edge of the blade. The use of the exposed radially inner edge of the bearing blade allows for an open bearing design that can improve flushing of the bearing surface. Thus, bearing heating can be reduced. Similarly, blood clogging and clotting in the bearing area can be reduced. In particular, having the inner edge of the rotating blade acting as a bearing mating part has the inherent advantage of radially centrifuging the blood boundary layer away from the bearing surface. That is, a centrifugal force is generated that helps to remove deposited blood, which has a higher density than the blood flowing radially outwardly away from the fixed bearing surface. Thus, the bearing design helps to flush the mating surface of the bearing.

[0009] Preferably, the fixed bearing comprises at least one pin or cone extending along the axis of rotation. The fixed bearing may be substantially cylindrical or tapered in shape and may vary in length along the axis of rotation. For example, the fixed bearing may extend axially along less than half the length of the impeller, or it may extend substantially along the entire length of the impeller. Especially when the fixed bearing is relatively short, the bearing may comprise two fixed bearings extending axially from both axial ends towards or into the impeller.

[0010] Regardless of the particular design and shape of the fixed bearing, the fixed bearing may be referred to as a "pin" and the bearing may be referred to as a "pin bearing." These terms are not limited to a particular pin design, but rather refer to all types of fixed bearing and blade arrangements within the scope of the present invention, i.e., specifically, fixed bearings having radially outwardly facing bearing surfaces that interact with the exposed radially inner edges of the impeller blades.

[0011] The rolling bearing surface may extend along substantially the entire length of the exposed radially inner edge of at least one blade. This results in a large bearing surface, which is advantageous for example for heat dissipation. The heat dissipation is improved due to the fact that the bearing is formed on the blade itself, where heat dissipation will take place more actively. Alternatively, it may extend along only a part of the length of the exposed radially inner edge of the blade. In particular, the rolling bearing surface may be formed as one or more separate segments along the exposed radially inner edge of the blade, in order to reduce the size of the contact area of ​​the fixed and rolling bearing surfaces. This can be achieved, for example, by a specific concave-convex shape of the bearing surface on the inner blade edge, which can be formed by a convexity of the profile, or by a coating, insert, etc. As will be explained in more detail below, specific materials can be used for the coating and the insert.

[0012] In one embodiment, the fixed bearing may have a central axial passage extending therethrough. For example, the fixed bearing or the pin may have an axial channel, allowing blood to flow over the axial end face of the pin to clean the gap between the pin and the impeller. Additionally, if the impeller also has a central axial passage, blood may flow from the pin passage into the impeller passage.

[0013] The fixed bearing may be coupled to the pump casing by a support structure with at least one opening to allow blood to pass axially through it. For example, the fixed bearing may be supported by a strut connected to the pump casing. This may be particularly useful if the fixed bearing is located in the region of the blood inlet, since the pin can be located at the blood inlet while blood can enter the pump casing through the opening defined by the strut. This may also apply to the blood outlet if blood is to be allowed to flow axially out of the pump casing. Alternatively or additionally, the support structure may be sized and shaped to guide the blood flow radially. The support structure may have a tapered shape, for example a straight or curved cone forming a socket for the pin, and the support structure may widen in the downstream direction and be located near the blood outlet.

[0014] In general, the pin bearing concept described above applies to various designs of impellers, and in particular at least one blade, so long as a rotational bearing surface is formed on the exposed radially inner edge of the blade, or in some cases on a bearing structure coupled to the exposed radially inner edge of the blade. In particular, the at least one blade may be attached to the inner surface of the impeller hub, the outer surface of the impeller hub, or both. If the blade is located on the outer surface of the hub, the exposed radially inner edge may be located in a region of the blade that extends axially beyond the hub. If the blade is located on the inner surface of the hub, they may be considered inner blades and may be located in the passage of the impeller, as described in more detail below. It will be understood that a combination of "inner" and "outer" blades may be included in a single impeller.

[0015] According to one embodiment, the impeller includes at least one outer blade disposed on an outer surface of the impeller hub and sized and shaped to convey blood from the blood flow inlet to the blood flow outlet. The blood pump impeller also includes a blood flow passage extending through the impeller hub, and at least one inner blade disposed within the passage and sized and shaped to convey blood therethrough. A rotational bearing surface is provided on an exposed radially inner edge of at least one of the inner blades, or at least one of the outer blades, or both the inner and outer blades.

[0016] By providing inner blades in the impeller passages in addition to the outer blades, blood flow from the blood inlet toward the blood outlet can be supported by the inner blades pumping blood through the blood flow passages of the impeller, especially when the blood flow through the impeller passages is directed in the same direction as the main blood flow from the blood inlet to the blood outlet ("forward flow direction"). Regardless of the direction of flow in the blood flow passages of the impeller, the overall circulation of blood within the pump casing can be improved by the inner blades, thereby improving flushing and cooling of gaps, bearing surfaces, and other surfaces within the pump casing. The inner blades are located in the blood flow passages of the impeller and rotate with the impeller, so no additional space or additional drive mechanisms are required.

[0017] Preferably, the inner blades have a size and shape that allows them to convey blood through the passage to the bearing. In particular, this means that blood may be conveyed by the inner blades to, into or along the bearing. The inner blades are particularly advantageous when the bearing is a contact type bearing, since they generate an active cleaning flow to the bearing, preferably in the forward flow direction, cleaning and cooling the bearing. Heat dissipation is maximized. In this way, blood clotting and clogging in the bearing can be effectively reduced or avoided. In certain pump designs, a cleaning flow in the "backflow direction" (i.e. opposite to the "forward flow direction") can be advantageous. For example, a large diameter blood pump can benefit from having a pressure gradient in addition to the inner blade impeller that creates a very high blood backflow without affecting the overall pump flow.

[0018] The blood flow passage of the impeller may extend axially, preferably completely, at least partially along at least a portion of the impeller, in particular the hub of the impeller. At least a portion of the passage, in particular the portion of the passage where the inner blade is located, may be aligned with the axis of rotation, thereby improving the pumping of blood by the inner blade as it rotates about the axis of rotation. Furthermore, the inner blade may physically remove any deposited blood via the action of the highly turbulent blood flow in the bearing area as well as in the vicinity of the pin bearing surface. In other words, the exposed radially inner edge of the inner blade may act like a wiper blade on the fixed bearing surface of the fixed bearing part.

[0019] The impeller passage may have a portion or portions that do not extend along the axis of rotation, but are inclined relative to the axis of rotation. In particular, one or more ends of the passage in the impeller may be inclined relative to the axis of rotation. However, it is preferred that the blood flow passage extends completely through the impeller along the axis of rotation from a first axial end or opening to a second axial end or opening. The inner blades can then pump blood axially through the blood flow passage of the impeller. If the axial passage extends completely through the impeller along the axis of rotation, the impeller may be considered to be hollow or to have a hollow hub, for example a hollow cylinder or hollow cone, with the outer blades being located on the outer surface of the hollow hub and the inner blades being located on the inner surface of the hollow hub. It will be understood that any other suitable hollow shape, such as a generally cylindrical, not necessarily strictly cylindrical, or tapered or other tubular shape, may also be selected for the impeller.

[0020] In one embodiment, the bearing may be located in the blood flow path. The bearing may be located in the impeller passage to improve cleaning and cooling of the bearing since it is located directly in the blood flow pumped through the impeller passage. The fixed bearing part may comprise at least one pin extending along the axis of rotation, at least a part of the pin being configured to engage the exposed radially inner edge of the blade, in particular of the inner blade, or to engage a bearing structure attached to the exposed radially inner edge of the blade to form at least one bearing. It will be appreciated that the pin may be substantially cylindrical or tapered to form a conical shape. The latter also allows for compensation of axial forces, so that the bearing can act as an axial and radial bearing. The pin may extend only towards the passage or inside its end, or may extend a longer distance inside the passage. For example, it may extend along at least half, preferably at least 3 / 4, of the length of the impeller passage. In a preferred embodiment, the pin may extend entirely through the impeller passageway, i.e., at least along the entire length of the passageway in the impeller. The length of the pin may be greater than the length of the blood flow path of the impeller. Regardless of the length of the pin, the maximum diameter of the pin may be less than the minimum diameter of the impeller passageway. This allows blood to flow through the passageway past the pin.

[0021] In particular, the inner blades may have at least one exposed radially inner edge that defines a rotating bearing surface. That is, at least the radially inner edge of the inner blade may engage at least a part of the fixed bearing surface, for example the outer peripheral surface of the pin, forming at least one bearing. The use of the inner blades as bearing structures simplifies the construction of the blood pump, since no additional bearing structures are required. It is particularly advantageous if the pin extends through the entire impeller passage. The edge of the inner blade may contact the outer peripheral surface of the pin along its entire length, or at least along approximately its entire length. In addition, since the inner blades form the dynamic part of the bearing, heat dissipation is maximized, especially if the inner blades are made of a material with a high heat transfer coefficient. Since this bearing extends through the blood flow path of the impeller, the bearing is effectively cooled and flushed. The inner blades have multiple functions. They act as pumping means for pumping blood through the impeller passage, actively cleaning the bearing, while at the same time functioning as bearings themselves. They also act as heat sinks located in the turbulent flow region to maximize heat dissipation. The radially inner edges of the blades may be circumferentially tapered to improve hydrodynamic bearing function compared to edges parallel to the pin surface.

[0022] In an embodiment in which there is at least one outer blade and at least one inner blade, at least one blade of the impeller may be arranged on the hub of the impeller such that the blade is divided by the hub into an inner part forming the inner blade and an outer part forming the outer blade. In other words, the inner blade may be aligned with the outer blade, or the inner blade may be "continuous" with the outer blade through the hub of the impeller, especially if the impeller has a hollow hub. In particular, the inner and outer blades may have corresponding dimensions and shapes. Regardless of the particular dimensions and shapes of the blades, the hollow hub may be continuous or may be interrupted by an opening to allow blood to flow from the inner blade to the outer blade or vice versa, which is advantageous for hydraulic balance. In general, it is important that the blood flow caused by the inner blade and the blood flow caused by the outer blade are hydraulically balanced. As a result, both sets of blades induce a forward blood flow, especially within the operating range of pressures up to 200 mmHg.

[0023] For example, the inner and outer blades may extend the same distance radially inward and outward from the impeller hub, respectively. This design is simple since it essentially defines a set of blades separated into inner and outer blades by the hollow impeller hub. However, in other embodiments, the inner and outer blades may not be aligned or correspond in size and shape. The inner blades may be smaller, for example, than the outer blades. The inner and outer blades may have different angles of incidence, exit and / or pitch, depending on the hydraulic requirements. Alternatively, the number of outer blades and the number of inner blades may be the same or different, regardless of whether the outer and inner blades are aligned or correspond in size and shape. For example, there may be more inner blades than outer blades, for example three inner blades and two outer blades. It will be understood that there may be only a single inner blade or a single outer blade, or there may be more than two inner or outer blades. In general, when multiple blades are provided, only one of them, not all of them, may form part of the bearing, and another blade may be spaced from the fixed bearing surface. The inner or outer blades or both may spiral about the axis of rotation, i.e., they may be helical and may have a variable pitch, or the blades may extend linearly in the axial direction.

[0024] The inner blade may completely correspond to the outer blade, in fact both the inner and outer blades form a single blade held in place by the outer hub so that the blade extends centrally towards the hub and forms a radial bearing with a central pin. The outer hub may house a set of magnets that constitute the rotor of an electric motor driven by a stator coil located on the outer surface of the pump casing.

[0025] In one embodiment, the pump casing may have a blood flow inlet in the main direction of flow and a secondary blood flow inlet axially spaced from the blood flow outlet. For example, the blood flow inlet may be located at an upstream end of the pump casing and the secondary blood flow inlet may be located at an opposite downstream end of the pump casing. However, the secondary blood flow inlet may also be located circumferentially within the pump casing. The secondary blood flow inlet may be used to create a wash flow along the impeller. For this purpose, the impeller may include at least two blades, at least one of which is associated with the blood flow inlet to transport blood from the blood flow inlet to the blood flow outlet in the main direction of flow and at least another of which is associated with a secondary blood flow inlet to transport blood from the secondary blood flow inlet to the blood flow outlet in a direction opposite to the main direction of flow.

[0026] At least two blades may be located at axially opposing portions of the impeller adjacent to the middle portion, and at least one blade associated with the secondary blood flow inlet may be sized and shaped to convey blood along the middle portion of the impeller. That is, the impeller may be considered a "double impeller" where blood is pumped in two opposing directions toward the center of the impeller by opposing blades located at the ends of the impeller. While the blades associated with the blood flow inlet generate the primary blood flow, the blades associated with the secondary blood flow inlet cause an active wash flow along the hub of the impeller. In this embodiment, the impeller may include two of the aforementioned pin bearings at its opposite axial ends, with the exposed radially inner edge of each blade supported by a respective pin. The "secondary" blades are used to take blood from outside the pump and push it through a radial gap between the magnetic drive and the pump casing to wash and cool the electric motor formed by the magnetic drive and the stationary stator coils located on the outer surface of the pump casing. It will be appreciated that the secondary pump may be designed as an axial flow, mixed flow, or substantially radial pump.

[0027] In one embodiment, instead of or in addition to using the exposed radially inner edges of the blades as the rotating bearing surface itself, a bearing structure coupled to the exposed radially inner edges of the blades can be used for bearing. The rotating bearing surface may be defined by at least one ring that engages at least a portion of the pin. The at least one ring may be provided separately from the inner blades, or may be coupled to at least one or all of the inner blades in addition to or instead of the rotating bearing surface formed by the exposed radially inner edges of the inner blades. In other words, the bearing surface of the bearing structure may be formed only by the at least one ring, or it may be formed by the at least one ring along the radially inner edges of the blades.

[0028] Instead of or in addition to a ring, the bearing structure may comprise at least one wing that can engage at least a portion of the pin and be coupled to at least one or all of the inner blades. The at least one wing may have an arc shape that corresponds in size and shape to the outer circumferential surface of the pin to form a bearing that provides a specific radial centering of the impeller. It will be understood that the rings described above may be formed by such wings. For example, at least two, e.g., two, three, or four, circumferentially adjacent wings may be connected to form a ring. The wings or rings may be located at one or more positions along the length of the impeller passage. The wings may have a specific geometric shape that maximizes the amount of blood or plasma only that enters the bearing area. Also, centrifugal forces in the vicinity of the pin bearing may be used to move red blood cells and other cellular blood components from the bearing area radially away from the bearing area.

[0029] In another embodiment, the rotary bearing surface may be sized and shaped to engage with the axial end of the fixed bearing part, forming said at least one bearing, and may be connected to at least one or all of the blades. The rotary bearing surface may be a continuous surface or may include separate segments that may be regularly, e.g., symmetrically arranged with respect to the axis of rotation. The rotary bearing surface may form, for example, a cup, a dome, a hemisphere, a cone, or any other suitable rotationally symmetric surface whose size and shape correspond to the axial end surface of the pin. This type of bearing provides radial centering as well as axial support for the impeller.

[0030] The blood pump is preferably driven by a radial drive, with an electrical arrangement coupled to the pump casing and arranged circumferentially around the impeller and possibly the pump casing to generate a rotating magnetic field. Permanent magnets in the impeller are magnetically coupled to the rotating magnetic field of the stator coils to cause the impeller to rotate around the axis of rotation. The magnets can be integrated in the impeller, in particular in the blades, preferably in the outer blades. The radial drive allows a compact design of the blood pump, in particular the aforementioned pins extending into the passages of the impeller can be designed independent of the bearings. However, it will be understood that any other suitable drive mechanism can be used for the blood pump. In particular, a drive mechanism suitable for an intravascular catheter pump is preferably designed for compactness, high energy density.

[0031] The bearings described above may be supported by additional bearings. The additional bearings may be designed to withstand axial loads in one or both axial directions along the rotation axis, particularly to cushion the pin bearings. In one embodiment, the fixed bearing part and the impeller may each include at least one magnet. The magnets in the fixed bearing part and the magnets in the impeller may be arranged in radial alignment and disposed in the fixed bearing part and the impeller, respectively, so that an axial repulsive magnetic force is generated between the fixed bearing part and the impeller. Thus, the axial end faces of the impeller and the fixed bearing part are not in contact with each other due to the repulsive magnetic force, so that wear and heat generation of the axial end faces are avoided, and the repulsive magnetic force helps to align the impeller axially in the pump casing. This may be particularly useful when the repulsive magnetic force acts on the impeller from both opposing axial ends in opposite directions.

[0032] In one embodiment, at least one of the fixed and rotating bearing surfaces may comprise a material having a higher hardness than the material of the fixed bearing portion and the rest of the impeller, respectively, to reduce wear of the bearing surface. For example, a coating or insert of a specific material may be used to reduce wear. A suitable material may be ceramic. To increase heat dissipation, the blade may be formed, for example, of metal, while the rotating bearing surface of the blade, particularly the exposed radially inner edge of the blade, may be fully or partially coated with ceramic or have a ceramic insert. Inserts such as ceramic inserts may be insert molded or affixed to the surface of the inner blade that contacts the surface of the pin to increase the life of the bearing. Due to the inherent high heat dissipation of the blade, high heat generation can be well accommodated without adversely affecting blood deposition in the bearing area or wear of the bearing. With regard to heat dissipation, silicon carbide may be preferred for the insert or coating. The mating material may also be steel, which may be coated, for example, with a diamond coating. In addition, it is preferable to keep the relative speed, at which sliding of the mating parts against each other is minimal, to a minimum, preferably less than 1.5 meters / sec, which corresponds to a shaft diameter of approximately 1 mm for a pump with an outer diameter of 6 mm and a design speed of 30,000 rpm.

[0033] In another embodiment, the impeller may include at least one secondary blade disposed on an axial end face of the impeller, which may improve cleaning of the bearing surface or gap between the impeller and the pump casing, or may provide a hydrodynamic axial bearing when interacting with a respective preferably smooth inner surface of the pump casing. [Brief description of the drawings]

[0034] The foregoing 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 purposes of illustrating the disclosure, however, reference is made to the drawings. The scope of the disclosure is not limited, however, to the specific embodiments disclosed in the drawings. [Figure 1] FIG. 1 is a perspective view of one embodiment of a blood pump. [Diagram 2] FIG. 2 is a cross-sectional view showing the blood pump of FIG. [Diagram 3] FIG. 2 is a perspective view showing a portion of the blood pump of FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view showing the portion shown in FIG. [Diagram 5] FIG. 2 is a perspective view showing an impeller of the blood pump of FIG. 1. [Figure 6] FIG. 6 is a cross-sectional view showing the impeller shown in FIG. [Figure 7] FIG. 2 is a perspective view showing a pin of the blood pump of FIG. 1. [Figure 8] FIG. 13 is a perspective view showing an impeller arrangement of another embodiment. [Figure 9] FIG. 13 is a perspective view showing an impeller arrangement of another embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the impeller arrangement of FIG. [Figure 11] FIG. 10 is a perspective view showing the impeller of FIG. [Figure 12] FIG. 10 is a perspective view and a semi-transparent view of the impeller of FIG. [Figure 13] FIG. 10 is a perspective view of a pin of the impeller arrangement of FIG. [Figure 14] FIG. 11 is a perspective view showing an impeller according to another embodiment. [Figure 15] FIG. 11 is a perspective view showing an impeller according to another embodiment. [Figure 16] FIG. 11 is a perspective view showing an impeller according to another embodiment. [Figure 17] FIG. 17 is a cross-sectional view showing the impeller of FIG. 16. [Figure 18] FIG. 17 is an enlarged cross-sectional view showing the impeller of FIG. 16. [Figure 19]FIG. 13 is a side view of an impeller assembly according to another embodiment. [Figure 20] FIG. 20 is a cross-sectional view of the assembly of FIG. 19. [Figure 21] FIG. 20 is a perspective cross-sectional view of the assembly of FIG. 19. [Figure 22] FIG. 13 is a side view of an impeller assembly according to another embodiment. [Figure 23] FIG. 23 is a cross-sectional view of the assembly of FIG. 22. [Figure 24] FIG. 23 is a perspective cross-sectional view of the assembly of FIG. 22. [Diagram 25] FIG. 13 is a side view of an impeller assembly according to another embodiment. [Figure 26] FIG. 26 is a cross-sectional view of the assembly of FIG. 25. [Figure 27] FIG. 26 is a perspective cross-sectional view of the assembly of FIG. 25. [Figure 28] FIG. 11 is a cross-sectional view of an impeller assembly according to another embodiment. [Figure 29] FIG. 29 is a perspective view showing the impeller of FIG. 28. [Diagram 30] FIG. 29 is a perspective view showing an impeller together with the fixed bearing portion of FIG. 28. [Diagram 31] FIG. 4 is a cross-sectional view showing an impeller according to another embodiment. [Diagram 32] FIG. 4 is a cross-sectional view showing an impeller according to another embodiment. [Diagram 33] FIG. 11 is a cross-sectional view showing a blood pump according to another embodiment. [Diagram 34] FIG. 34 shows the impeller of the blood pump of FIG. 33. [Diagram 35] FIG. 34 shows an impeller together with a fixed bearing part of the blood pump of FIG. 33. [Diagram 36] FIG. 34 shows an impeller together with a fixed bearing and drive unit of the blood pump of FIG. 33. [Figure 37] FIG. 34 is a perspective view of the blood pump of FIG. 33. [Figure 38] FIG. 11 is a cross-sectional view showing a blood pump according to another embodiment. [Figure 39]FIG. 2 is a cross-sectional view of an embodiment of an impeller. [Diagram 40] FIG. 2 is a cross-sectional view of an embodiment of an impeller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] With reference to Figures 1 and 2, a perspective view and a cross-sectional view of a blood pump 1 are shown, respectively. The blood pump 1 comprises a pump casing 2 having a blood inlet 21 and a blood outlet 22. The blood pump 1 is designed as an intravascular pump, also called a catheter pump, and is deployed in a patient's blood vessel by a catheter 25. The blood inlet 21 is connected to a flexible cannula 23, which in use can be placed through a heart valve, for example the aortic valve. The blood outlet 22 is located on the side of the pump casing 2 and can be placed in a heart vessel, for example the aorta. The blood pump 1 is connected to the catheter 25 in order to provide the blood pump 1 with power for driving the pump 1 by a drive 5, as will be explained in more detail below. It will be understood that in general the flow in the blood pump may be in the opposite direction to that described in this disclosure. For example, in the embodiment of Figure 1, 22 can denote the blood inlet and 21 the blood outlet.

[0036] 3-6, the impeller 3 is provided for conveying blood from the blood inlet 21 to the blood outlet 22, and is mounted in the pump casing 2 so as to be rotatable about a rotation axis. The rotation axis is preferably a longitudinal axis of the impeller 3. The impeller 3 is rotatably supported by a bearing 60 formed inside the impeller 3 with a pin 4 and a bearing structure, thus a so-called pin bearing. The bearing structure is formed by an inner blade 32, as described in more detail below. The outer blade 31 is provided on a hub 36 of the impeller 3, which conveys blood when the impeller 3 rotates. The rotation of the impeller 3 is generated by a drive 5 arranged circumferentially around the pump casing 2. The drive 5 includes a stator of an electric motor which generates a rotating magnetic field. The magnets of the outer blades 31 of the impeller 3 interact with the rotating magnetic field, causing the rotation of the impeller 3 about the rotation axis. It is also possible to form the outer blades 31 of a magnetic material. As can be seen in Figure 2, the outer blades 31 are thicker than the inner blades 32 to provide sufficient space for magnets or magnetic material. The illustrated blood pump 1 is a mixed type blood pump, where the main direction of flow is axial. It will be understood that depending on the arrangement of the impeller 3, and in particular the blades 31, the blood pump 1 may also be a purely axial blood pump.

[0037] The impeller 3 includes a blood flow passage 33 that extends along the axis of rotation throughout the impeller 3. In this embodiment, the impeller 3 is hollow, i.e., the hub 36 of the impeller forms a cylindrical tube. The inner blades 32 are disposed within the passages 33. The pins 4 extend through the passages 33, and are configured such that the pins 4 have a smaller diameter than the passages 33, allowing blood to flow over the pins 4. As shown in Figures 3-6, the exposed radially inner edges 50 of the inner blades 32 have radially inwardly facing surfaces 62 that engage or contact the outer peripheral surface 61 of the pins 4, and are configured to form a bearing 60 that rotatably supports the impeller 3. To improve the bearing 60, and in particular its hydrodynamic properties, the edges 50 of the inner blades 32 may be circumferentially tapered.

[0038] The pin 4, i.e. the fixed bearing part, is shown separately in FIG. 7. The pin 4 has a longitudinal body with a first axial end 41 and a second axial end 42. The first axial end 41 includes an enlargement for fixing the pin 4 to the pump casing 2, whereby the pin 4 is fixed. As can be seen for example in FIG. 4, the enlargement 41 is shaped to guide the blood flow towards the opening of the blood outlet 22. Instead of a single pin 4 extending entirely through the impeller 3, two short pins may be provided, each extending into the first and second axial ends 34, 35 of the impeller 3. The outer peripheral surface 61 of the pin 4 provides a fixed bearing surface for the bearing 60.

[0039] When the rotation of the impeller 3 is caused by the driver 5, blood is pumped by the outer blades 31 from the blood inlet 21 to the blood outlet 22. At the same time, the blood is transported by the inner blades 32 from the first axial end 34 through the passages 33 of the impeller 3 to the second axial end 35. In this embodiment, the blood flow through the passages 33 of the impeller 3 is directed in the same direction as the main blood flow from the blood inlet 21 to the blood outlet 22. That is, the blood flow through the passages 33 is directed in a forward direction. The bearings 60 formed by the pins 4 and the inner blades 32 are cooled and actively washed by the blood flow generated by the inner blades 32 to avoid blood clogging and clotting.

[0040] In general, it is important that the blood flows induced by the inner and outer blades are hydraulically balanced so that both sets of blades induce forward blood flow. This can be achieved by providing openings in the hub of the impeller to connect the blood flow paths in the impeller environment. FIG. 8 shows an embodiment of an impeller 603, where the hub 636 includes a number of axially spaced rings carrying the blades. The blades are divided by the hub 636 into outer blades 631 and inner blades 632, the exposed radially inner edges 650 of the inner blades forming the bearing rolling surfaces as described in relation to the previous embodiment. The openings, i.e. the spaces between the rings 636, make it possible to achieve a hydraulic balance of the blood flows induced by the inner blades 632 and the outer blades 631, respectively. It will be appreciated that the openings can be designed in different ways. For example, more or fewer rings can be provided, and the axial dimensions of the rings and the spacing between the rings can be larger or smaller as desired. The openings may also be formed as simple holes in the hub of the impeller which may be of any size and shape depending on the hydraulic requirements.

[0041] Figures 9-13 illustrate another embodiment corresponding to the embodiment shown in Figures 1-7, except for the design of the outer blade 131, the inner blade 132 and the pin 104. As can be seen in Figures 9-12, in the embodiment of Figure 8, the inner blade 132 is aligned with the outer blade 131, and the inner blade 132 is continuous with the outer blade 131 through the hub 136 of the impeller 103 or is mirrored at the hub 136. The inner blade 132 and the outer blade 131 are separated by the hub 136 of the hollow impeller 3 and correspond to each other in size and shape. In this embodiment, two inner blades 132 and two outer blades 131 are provided, the outer blades 131 extend helically on the outer surface of the hub 136 and the inner blades 132 extend helically on the inner surface of the hub 136. The hub 136 is hollow and cylindrical with a passageway 133 extending from a first axial end 134 to a second axial end 135. A cone 137 is attached to the second axial end 135 to direct blood flow toward the blood flow outlet 22 of the blood pump 1.

[0042] In this embodiment, a ring 155 is attached to the inner blade 132 and provides a rotational bearing surface 162 that engages the pin 104, in particular a particular outer surface 161 of the pin 104 to form the bearing 160. The ring 155 radially centers the impeller 103 and guides the rotation of the impeller 103 about its axis of rotation. The pin 104 is shown in FIG. 13 and is shorter than in the previously described embodiment. It has a first axial end 141, which includes a plate that fixes the pin 104 in the pump casing, and a second axial end 142. The impeller 103 shown in FIGS. 9-12 can also be used with a longer pin 4, as shown in FIG. 7. The ring 155 may provide only a bearing surface. However, more than one ring may be arranged along the length of the impeller 103, for example one ring at each of the first and second axial ends 134, 135, particularly when the impeller 103 is used with a longer pin. In the latter case, two short pins 104 may be provided, one at the first axial end 134 of the impeller 103 and the other at its second axial end 135. In either case, the bearing fit area can be limited to a minimum.

[0043] FIG. 14 shows another embodiment in which wings 153 are attached to the inner blades 132 that define the bearing surface 162. This embodiment is similar to the embodiment in which a ring 155 defines the rotational bearing surface 162. The separate wings 153 can improve flushing of the bearing 160 compared to a closed ring. FIG. 15 shows another embodiment in which the impeller 103 does not have any additional bearing surface, but as in the embodiment of FIGS. 1-7, the rotational bearing 162 is defined by the radially inner edges 150 of the inner blades 132. In another embodiment, the exposed radially inner edges 150 of the inner blades 132 can also function as a rotational bearing surface in addition to the bearing surface 162 formed by the ring 155 or wings 153. The size and shape of the pin or pins are then selected such that the radially inner edges 150 of the inner blades 132 engage the pin(s). Further, it will be appreciated that the number of inboard blades 132 may differ from the number of outboard blades 131 to match the hydraulic performance of both blades.

[0044] 16-18 show another embodiment, in which the bearing structure comprises a curved protrusion 152 forming an additional bearing surface 163, the size and shape of which is adapted to the size and shape of the ring-shaped portion 151 as well as the axial end 142 of the pin 104. In particular, the protrusion 152 may form a hemispherical shape corresponding to the hemispherical end 142 of the pin 104. It will be understood that the protrusion 152 may be connected to form a closed surface engaging the pin 104. Similarly, the shape of the protrusion 152 and the end 142 of the pin 104 does not necessarily have to be hemispherical, but may be, for example, conical. In this embodiment, the bearing also provides radial centering as well as axial support of the impeller 103. Apart from that, in this embodiment, the number of inner blades 132 is different from the number of outer blades 131. Three inner blades 132 are arranged in the passage 133 of the impeller 103, while only two outer blades 131 are provided on the outer surface of the hub 136.

[0045] 19-21, there is shown an impeller assembly according to another embodiment, which can be used in a blood pump similar to that shown in FIG. 1. In particular, the impeller assembly can be used in an intravascular catheter pump and can be disposed in a pump casing connected to a catheter as shown and described in relation to FIG. 1. The impeller assembly of FIGS. 19-21 includes an impeller 203 having a set of outer blades 231 to convey blood from a blood flow inlet to a blood flow outlet of the blood pump. The impeller 203 further includes a blood passage 233 extending axially through the impeller 203. A set of inner blades 232 is disposed within the blood flow passage 233 at a downstream end of the passage 233. In this embodiment, the impeller 203 is tapered such that the blood flow (indicated by the arrows) is guided radially outward. The blood passage 233 is also tapered, increasing in diameter towards the downstream end. However, any other shape, such as a cylindrical shape, is also suitable for the blood passage 233.

[0046] The impeller 203 is supported by two bearings 260, 263, one at the upstream end of the impeller 203 and one at the downstream end. The downstream bearing 263 is provided with a fixed bearing part 211 configured to be coupled to the pump casing. The fixed bearing part 211 includes a conical projection 206 that extends into the blood flow passage 233 of the impeller 203 and interacts with the inner blade 232 forming the bearing 263. More specifically, the exposed radially inner edge 251 of the inner blade 232 interacts with the cone 206. The exposed radially inner edge 251 defines a rolling bearing surface 265 that engages a fixed bearing surface 264 of the cone 206. Due to the conical shape of the fixed bearing part, the bearing 263 provides axial and radial support for the impeller 203. At the same time, the inner blades 232 actively pump blood to the bearing 263 (indicated by arrows), particularly along the bearing surfaces 264, 265, to clean and cool the bearing 263. Blood flow through the blood passages 233 of the impeller 203 exits the passage 233 at the downstream end and joins the main blood flow through the gap 214 between the impeller 203 and the fixed bearing part 211.

[0047] At its upstream end, the impeller 203 is supported by another bearing 260. A fixed bearing part 210 is provided that can be coupled to the pump casing. As best shown in FIG. 21, the fixed bearing part 210 is ring-shaped and includes a number of openings 212 that allow blood to enter the impeller area. The openings 212 may have any suitable number and design to allow blood to pass through. In this embodiment, the openings 212 are defined by a number of struts 213. The number of struts 213 can be selected as desired, such as at least two, three, four or five. The struts 213 support a pin 204 that extends along the axis of rotation towards the impeller 203. The pin 204 defines a fixed bearing surface 261 that interacts with a rotational bearing surface 262 defined on the exposed radially inner edge 250 of the outer blade 231. The outer blades 231 extend beyond the hub 236 of the impeller 203 to form an exposed radially inner edge 250 of the outer blades 231. That is, the outer blades 231 have axial ends that protrude beyond the hub 236 of the impeller. In the present case, all three outer blades 231 extend beyond the hub 236 by approximately the same distance to form an exposed radially inner edge 250 that engages the pin 204. However, it may be sufficient if not all outer blades 231 form an exposed radially inner edge. This type of bearing is an open design in which the bearing surfaces 261, 262 are in contact with the blood. The bearing surfaces 261, 261 are effectively washed and cooled. The washing of the bearing surfaces 261, 262 during the rotation of the blades 231 is indicated by the arrows in FIG. 19. The rotating blades 231 only centrifuge the deposited blood radially outward from the bearing 260. This flushing flow is independent of the primary blood flow caused by the blades 231 .

[0048] As can be seen in Figures 20 and 21, the pin 204 has an axial passageway 234 through which blood can flow. Specifically, the passageway 234 in the pin 204 is aligned with the blood flow passageway 233 in the impeller 203, so that blood tends to flow into the passageway 233 in the impeller 203, increasing the amount of blood flow through the impeller 203 and providing effective and proactive cleaning of the bearings 263 as described above. Blood also enters the blood flow passageway 233 between the outer surface of the pin 204 and the distal end of the impeller 203 (as indicated by the arrow in Figure 20).

[0049] The impeller 203 can be further adjusted or alternatively driven by an arrangement including magnets or electromagnets 270, 271 as shown diagrammatically in FIG. 20. The magnet 271 in the fixed bearing 211 interacts with the magnet 270 of the impeller 203 to form a magnetic coupling. The magnets 270, 271 can be arranged to create an attractive or repulsive magnetic force to support the alignment of the impeller 203. It will be understood that any suitable drive can be used to cause the impeller 203 to rotate about its axis of rotation. For example, the magnet 270 of the impeller 203 can interact with a rotating magnetic field caused by an electric unit in the fixed bearing 211, i.e. axially, or by an electric unit surrounding the impeller, i.e. radially. Alternatively, the magnet 271 can be a permanent magnet or part of a rotating disk rotatably sealed against the blood.

[0050] Another embodiment of the impeller assembly is shown in Figures 22-24, which is substantially the same as the embodiment shown in Figures 19-21. The only difference is that secondary blades 235 are provided on the downstream end face of the impeller 203 in the gap 214. This enhances the blood flow through the gap 214 to clean the gap 214. Furthermore, the secondary blades 235 provide an axial hydrodynamic bearing to interact with the surface of the fixed bearing part 211.

[0051] 25-27, another embodiment of the impeller assembly is shown. In this embodiment, the impeller 303 has only outer blades 331 and no inner blades. Nevertheless, inner blades can also be provided in this embodiment acting like the inner blades described in connection with the embodiment shown in Figs. 1-7. The impeller 303 is supported by a bearing 360 having a fixed bearing portion 311 with a pin 304. The pin 304 extends through the entire blood flow passage 333 of the impeller 303. The blood flow passage 333 has a larger diameter than the pin 304 so that blood can flow through the blood flow passage 333 past the pin 304 and through the gap 314 at the axial end face of the impeller 303. The secondary blades 335 are provided to enhance blood flow through the gap 314 and to provide a hydrodynamic bearing. However, it will be understood that the secondary blades 335 may be omitted.

[0052] As in the previous embodiment, the outer blades 331 are disposed on the outer surface of the hub 336 of the impeller 303 and extend axially beyond the hub 236 to form an exposed radially inner edge 350 and define a rotational bearing surface 362. The rotational bearing surface 362 engages a fixed bearing surface 361 defined by the axial end of the pin 304 protruding from the passage 333 of the impeller 303. Thus, the bearing 360 is provided to support the impeller 303 axially and radially. The large diameter of the impeller passage 333 allows a certain amount of rotational movement of the impeller 303 that can be balanced by the hydrodynamic bearing formed by the secondary blades 335. As shown, the blades 331 are not aligned with the axis of rotation to form an open bearing 360 that allows blood to enter the bearing 360 axially (as indicated by the arrow) and flush the bearing surfaces 361, 362. They may also be aligned with the axis of rotation while still allowing blood to enter the bearing 360 axially.

[0053] Another embodiment of the impeller assembly is shown in Figures 28-30. It is similar to that of Figures 19-21, but does not include a blood flow path through the impeller. Figure 28 shows a cross section through an impeller 403 disposed in a pump casing 402 having a blood inlet 421 and a blood outlet 422. The blood inlet 421 is disposed at the axial end of the pump casing 402, and the blood outlet 422 is disposed radially about the pump casing 402. This is similar to the embodiment shown in Figures 1-7. This embodiment may thus comprise a flexible cannula at the inlet end and a catheter at the opposite end, as described in detail above. Similarly, an axial drive unit may be provided at the downstream end of the impeller 403 (not shown).

[0054] The impeller 403 includes a set of outer blades 431 that project axially from the hub 436 of the impeller 403 to define an exposed radially inner edge 450. The impeller 403 is supported in a bearing 460 formed by a rolling bearing surface 462 on the exposed radially inner edge 450 of the blades 431 and a fixed bearing surface 461 on the pin 404 of the fixed bearing part 410. The fixed bearing part 410 includes an opening 412 defined by a post 413 to allow blood to enter the impeller area. As in the previous embodiment, an axial passage through the pin 404 may be provided to allow blood to enter the gap 465 between the impeller 403 and the pin 404 to improve cleaning of the gap 465. To avoid contact between the impeller 403 and the pin 404 in the area of ​​the gap 465, permanent magnets 472, 473 are provided on the impeller 403 and the pin 404, respectively, to induce a repulsive magnetic force. It will be understood that this magnet arrangement may be used or omitted in any of the disclosed embodiments. In other configurations, the magnet may be a ring magnet such that blood can flow through the center along the axis of rotation.

[0055] Referring to FIG. 31, another embodiment of an impeller 703 is shown. As with the previous embodiment, the impeller 703 includes a tapered hub 736 with a set of outer blades 731 on the outer surface of the hub 736 to generate the primary blood flow. However, the blades 731 do not extend axially beyond the impeller hub 736. Instead, secondary blades 732 are provided at the tip 743 of the impeller 703. The secondary blades 732 are smaller than the primary blades 731 and form exposed radially inner edges 750 that are configured to engage with pins to form an open bearing, as described in connection with the previous embodiment. A shroud 740 is provided surrounding and connecting the secondary blades 732 and is configured to allow blood to flow from an inlet 741 to an outlet 742. Blood does not flow through the impeller hub 736, but only along the secondary blades 732.

[0056] The embodiment shown in FIG. 32 is substantially the same as that of FIG. 32, except that the shroud 740 is omitted. This results in a more open bearing design which may improve bearing flushing. The secondary blades 732 may be formed completely straight in the axial direction, rather than helical as shown in FIGS. 31 and 32. This results in a secondary centrifugal pump which further improves bearing flushing. In particular, deposited blood is centrifuged radially outward away from the inner edge 750 of the secondary blades 732. The impeller 703, and in particular the secondary blades 732, are easily manufactured. For example, the tip 743 of the impeller 703, together with the secondary blades 732, may be manufactured as an injection molded ceramic element.

[0057] 33-37, another embodiment of a blood pump is shown, which has an upstream portion substantially similar to the embodiment shown in FIGS. 28-30. The blood pump comprises a pump casing 502 having a blood inlet 521 and a blood outlet 522. The impeller 503 has outer blades 531 on the outer circumferential surface of the impeller hub 536 forming an exposed radially inner edge 550 as described above. The bearing 560 is formed by a bearing surface 562 on the exposed radially inner edge 550 and a fixed bearing surface 561 on the pin 504 of the fixed bearing part 510. The impeller hub 536 is tapered so that the blood flow is directed radially outward from the blood inlet 521 to the blood outlet 522. As explained above, magnets (not shown) which induce axial repulsion can be placed on the impeller 503 and the pin 504, respectively, to adjust the axial position of the impeller 503.

[0058] In this embodiment, the impeller 503 has a second set of blades 532 at the downstream portion of the impeller 503 and a second bearing 563 that is substantially identical to the bearing 560. The blades 532 form an exposed radially inner edge 552 that defines a rotating bearing surface 565 that engages a fixed bearing surface 564 on the pin 506. The pin 506 is contained in another fixed bearing part 511 that is substantially identical to the fixed bearing part 510. This is connected to a catheter 525 that provides power to the blood pump, for example. A secondary blood inlet 523 is formed at the downstream end of the pump casing 502. An opening in the fixed bearing part 511 allows blood to enter the impeller area from the near side in a direction opposite to the main direction of flow. The blades 532 are arranged to pump blood against the main direction of flow along the middle part 530 of the impeller 503 through the gap 514 towards the blood outlet 522 as shown by the arrow. This allows flushing of the gap between the pump casing 502 and the middle part 530 of the impeller 503, which includes magnets 570 rotated by an electric drive unit 505 arranged circumferentially around the impeller 503. The blades 532 are designed to provide sufficient backflow to clean the gap 514, but at the same time not affect the main blood flow. In particular, the blades 532 may be smaller than the blades 531. As in other embodiments, either of the blades may have a coating or insert at their exposed radially inner edges, including a material with improved heat dissipation and wear resistance properties, such as ceramic. The axial forces of the two axial impeller parts can be minimized by the opposing pumping directions.

[0059] FIG. 38 shows another embodiment of a blood pump substantially similar to the embodiment shown in FIGS. 33-37. The impeller 803 has two sets of blades 831, 832, forming respective bearings 860, 863. The blades 831 generate the main blood flow from the blood inlet 821 to the blood outlet 822. As in the previous embodiment, the secondary blades 832 generate a rear wash flow from the secondary blood inlet 823 through the gap between the stator coil 805 and the magnet 870 to the blood outlet. The secondary blood inlet 823 is directed towards the catheter 825. The hub 836 of the impeller has a shoulder 837 extending circumferentially around the hub 836 in the region of the blood outlet 822, which guides the main blood flow, and especially the wash flow, from the blood outlet 822 to the outside. That is, a local centrifugal and waterjet pump is generated by the main flow passing across the approximately vertical gap and the radial shoulder 837. It will be appreciated that the secondary blades 832 can be designed as a centrifugal pump having two or more blades in a straight rather than helical configuration to form a centrifugal pump.

[0060] Any of the aforementioned blades can be designed to suit the hydraulic requirements. In particular, the blades may be helical as shown in the examples. However, any of the aforementioned blades, particularly the secondary blades as mentioned above, can be designed to form a centrifugal pump. In other words, the blades may be straight and extend purely in the axial direction. FIG. 39 shows a cross section through a straight blade 1031 engaging the pin 1004. By providing a centrifugal pump with straight blades rather than helical blades, a higher centrifugal force can be generated that facilitates the removal of deposited blood from the bearing surfaces 1061, 1062 due to the higher density of deposited blood compared to blood. The deposits are transported radially outward away from the bearing surfaces 1061, 1062, which helps prevent blood clogging and clotting, thus reducing the risk of thrombosis. The blade 1031 shown in FIG. 39 has an enlarged base 1050. FIG. 40 shows another embodiment in which the blade 1131 engaging the pin 1104 does not have an enlarged base. This may improve centrifugation of deposited blood radially outwardly away from the bearing surfaces 1161,1162.

[0061] It will be understood that the described embodiments are merely illustrative and not limiting. In particular, various aspects and features of the embodiments can be combined or employed independently in different embodiments. For example, different designs of the described features with respect to the outer blades, inner blades, pins, blood flow paths through the pins or impeller, drive, magnets for alignment, etc. can be variably combined without departing from the scope of the invention.

[0062] The preferred embodiments are described in the following sections. 1. A blood pump comprising: a pump casing having a blood flow inlet and a blood flow outlet; and an impeller disposed within the pump casing and rotatably supported on the pump casing by at least one bearing for rotation about an axis of rotation, the impeller having at least one blade for transporting blood from the blood flow inlet to the blood flow outlet, the bearing including at least one fixed bearing portion coupled to the pump casing and having a fixed bearing surface facing radially outward, the bearing further including a rotating bearing surface interacting with the fixed bearing surface to form the bearing, the rotating bearing surface facing radially inward and formed on at least one exposed radially inner edge of the at least one blade or on a bearing structure coupled to the exposed radially inner edge of the blade.

[0063] 2. The blood pump of item 1, wherein the fixed bearing portion includes at least one pin or cone extending along the axis of rotation.

[0064] 3. The blood pump according to item 1 or 2, wherein the fixed bearing portion is substantially cylindrical or tapered in shape.

[0065] 4. The blood pump according to any one of items 1 to 3, wherein the at least one fixed bearing portion extends axially along less than half the length of the impeller or extends along substantially the entire length of the impeller.

[0066] 5. A blood pump as described in any one of items 1 to 4, including two bearings, each having a fixed bearing portion, the fixed bearing portions extending axially into the impeller at opposite axial ends of the impeller.

[0067] 6. The blood pump of any one of items 1 to 5, wherein the rotational bearing surface extends along substantially the entire length of the exposed radially inner edge of the at least one blade, or extends along only a portion of the length of the exposed radially inner edge of the at least one blade.

[0068] 7. The blood pump according to any one of items 1 to 6, wherein the fixed bearing portion has a central axial passage extending therethrough.

[0069] 8. The blood pump according to any one of items 1 to 7, wherein the fixed bearing portion is connected to the pump casing by a support structure having at least one opening to allow blood to pass therethrough in the axial direction.

[0070] 9. The blood pump according to any one of items 1 to 8, wherein the fixed bearing portion is coupled to the pump casing by a support structure that is sized and shaped to guide blood flow in a radial direction.

[0071] 10. The blood pump according to any one of items 1 to 9, wherein the at least one blade is disposed on at least one of an outer surface of a hub of the impeller and an inner surface of the hub of the impeller.

[0072] 11. The blood pump of any of items 1 to 10, wherein the at least one blade is disposed on an outer surface of a hub of the impeller and extends axially beyond the hub.

[0073] 12. A blood pump as described in any of items 1 to 11, wherein the impeller has a blood flow passage extending through a hub of the impeller, the impeller having at least one outer blade disposed on an outer surface of the impeller hub and sized and shaped to transport blood from the blood flow inlet to the blood flow outlet, and at least one inner blade disposed in the passage and sized and shaped to transport blood through the passage.

[0074] 13. The blood pump of claim 12, wherein the rotational bearing surface is formed on an exposed radially inner edge of at least one of the inner blade and the outer blade.

[0075] 14. The blood pump of item 12 or 13, comprising two bearings each having a fixed bearing portion extending axially within the impeller at opposite axial ends of the impeller, the rotating bearing surface of one of the bearings being formed on the exposed radially inner edge of the at least one inner blade, and the rotating bearing surface of the other of the bearings being formed on the exposed radially inner edge of the at least one outer blade.

[0076] 15. A blood pump according to any one of items 12 to 14, wherein the passage of the impeller extends at least partially or completely along the axis of rotation.

[0077] 16. The blood pump of item 15, wherein the at least one fixed bearing portion extends along at least half or at least 3 / 4 of the length of the impeller passageway, or extends completely through the impeller passageway.

[0078] 17. A blood pump described in any of items 12 to 16, wherein the at least one blade is positioned on the impeller such that the blade is divided by the hub of the impeller into an inner portion forming the inner blade and an outer portion forming the outer blade.

[0079] 18. The blood pump according to any one of items 12 to 17, wherein the maximum diameter of the fixed bearing portion is smaller than the minimum diameter of the passage of the impeller.

[0080] 19. A blood pump according to any one of items 1 to 18, wherein the pump casing has a blood flow inlet in a main direction of flow and a secondary blood flow inlet axially spaced from the blood flow outlet.

[0081] 20. The blood pump of item 19, wherein the impeller includes at least two blades, at least one of which is associated with the blood flow inlet to transport blood in a main direction of flow from the blood flow inlet to the blood flow outlet, and at least the other of which is associated with the secondary blood flow inlet to transport blood from the secondary blood flow inlet to the blood flow outlet in a direction opposite to the main direction of flow.

[0082] 21. The blood pump of item 20, wherein the at least two blades are positioned in axially opposed portions of the impeller adjacent a middle portion, and the at least one blade associated with the secondary blood flow inlet is sized and shaped to transport blood along the middle portion of the impeller.

[0083] 22. A blood pump described in any of items 1 to 21, wherein the bearing structure includes at least one of at least one ring surrounding at least a portion of the fixed bearing portion and at least one wing engaging with at least a portion of the fixed bearing portion.

[0084] 23. A blood pump according to any one of items 1 to 22, wherein the rotary bearing surface is sized and shaped to be able to engage with the axial end of the fixed bearing portion.

[0085] 24. A blood pump described in any one of items 1 to 23, comprising an electric motor that drives the impeller, the stator of the electric motor being coupled to a pump casing and arranged in a circumferential direction around the impeller.

[0086] 25. A blood pump as described in item 24, wherein the stator of the electric motor includes at least one electrical arrangement for generating a rotating magnetic field, and the impeller includes at least one permanent magnet.

[0087] 26. A blood pump described in any one of items 1 to 25, wherein the fixed bearing portion and the impeller each have at least one magnet, the magnet in the fixed bearing portion and the magnet in the impeller are aligned radially and disposed in the fixed bearing portion and the impeller, respectively, and an axial repulsive magnetic force is generated between the fixed bearing portion and the impeller.

[0088] 27. A blood pump according to any one of items 1 to 26, wherein at least one of the fixed bearing surface and the rotating bearing surface each comprises a material having a higher hardness than the material of the fixed bearing portion and the remainder of the impeller.

[0089] 28. A blood pump according to any one of items 1 to 27, wherein the impeller includes at least one secondary blade disposed on an axial end surface of the impeller.

[0090] 29. The blood pump according to item 28, wherein the secondary blade forms part of a hydrodynamic bearing.

[0091] 30. A blood pump comprising: a pump casing having a blood flow inlet and a blood flow outlet; and an impeller disposed in the pump casing for rotation about an axis of rotation, the impeller having a blood flow passage extending through a hub of the impeller, the impeller having outer blades disposed on an outer surface of the impeller hub and sized and shaped to transport blood from the blood flow inlet to the blood flow outlet, and inner blades disposed in the passage and sized and shaped to transport blood through the passage.

[0092] 31. The blood pump of item 30, wherein the impeller is rotatably supported within the pump casing by at least one bearing having an inner blade disposed within the passageway that is sized and shaped to transport blood through the passageway to the bearing.

[0093] 32. The blood pump of item 30 or 31, wherein the impeller passage extends at least partially or completely along the axis of rotation.

[0094] 33. The blood pump according to any one of items 30 to 32, wherein the impeller includes a bearing structure disposed within the passage.

[0095] 34. The blood pump of item 33, further comprising at least one pin extending along the axis of rotation, at least a portion of the pin engaging the bearing structure of the impeller to form the at least one bearing.

[0096] 35. The blood pump of item 34, wherein the pin extends along at least half or at least 3 / 4 of the length of the impeller passageway, or extends completely through the impeller passageway.

[0097] 36. A blood pump as described in item 34 or 35, wherein the maximum diameter of the pin is smaller than the minimum diameter of the passage of the impeller.

[0098] 37. A blood pump according to any of items 33 to 36, wherein the inner blades of the impeller form part of the bearing structure of the impeller and have at least one radially inner edge defining a bearing surface.

[0099] 38. The blood pump of items 37 and 34, wherein at least a portion of the radially inner edge of the at least one inner blade engages at least a portion of an outer peripheral surface of the pin to form at least one bearing.

[0100] 39. A blood pump according to any one of items 34 to 36, wherein the bearing structure of the impeller includes at least one ring that engages with at least a portion of the pin.

[0101] 40. A blood pump according to any one of items 34 to 36, wherein the bearing structure of the impeller includes at least one wing that engages with at least a portion of the pin.

[0102] 41. A blood pump described in any of items 34 to 36, wherein the bearing structure of the impeller is sized and shaped to engage with the axial end of the pin and has at least one bearing surface forming the at least one bearing.

[0103] 42. The blood pump according to any of items 30 to 41, wherein the inner blade is aligned with the outer blade.

[0104] 43. The blood pump according to any one of items 1 to 42, wherein the blood pump is an intravascular blood pump.

[0105] 44. The blood pump according to any one of items 1 to 43, wherein the blood pump is an axial blood pump, a centrifugal blood pump, or a mixed type blood pump.

Claims

1. A blood pump (1), comprising: a pump casing (2, 402, 502) having a blood inlet (21, 421, 521) and a blood outlet (22, 422, 522); an impeller (3, 203, 303, 403, 503, 603, 703, 803) disposed within the pump casing and rotatably supported on the pump casing by at least one bearing (60, 260, 360, 460, 560) about a rotation axis, the impeller (3, 203, 303, 403, 503) having at least one blade (31, 32, 231, 232, 331, 431, 531, 631, 731, 831) for transporting blood from the blood inlet to the blood outlet; The bearing (60, 260, 360, 460, 560) comprises at least one fixed bearing part (4, 204, 304, 404, 504) coupled to the pump casing and having a fixed bearing surface (61, 261, 361, 461, 561) facing radially outward, the bearing (60, 260, 360, 460, 560) further comprising a rotating bearing surface (62, 262, 362, 462, 562) which interacts with the fixed bearing surface (61, 261, 361, 461, 561). 2) to form said bearing (60, 260, 360, 460, 560), said rotating bearing surface (62, 262, 362, 462, 562) facing radially inward and formed on an exposed radially inner edge (50, 250, 350, 450, 550) of at least one of said at least one blade designed to draw deposited blood radially outward from said fixed bearing surface (61, 261, 361, 461, 561).

2. A pump casing (2) having a blood flow inlet (21) and a blood flow outlet (22); an impeller (103) disposed within the pump casing and rotatably supported on the pump casing by at least one bearing (160) about a rotation axis, the impeller (103) having at least one blade (131, 132) for transporting blood from the blood inlet to the blood outlet; The bearing (160) comprises at least one fixed bearing portion (104) coupled to the pump casing and having a fixed bearing surface (161) facing radially outward, the bearing (160) further having a rotating bearing surface (162) interacting with the fixed bearing surface (161) to form the bearing (160), the rotating bearing surface (162) facing radially inward and formed on a bearing structure coupled to the exposed radially inner edges of the blades.

3. 3. A blood pump as claimed in claim 1 or 2, wherein the fixed bearing portion includes at least one pin (104, 204, 304, 404, 504) or cone (206) extending along the axis of rotation, the fixed bearing portion being generally cylindrical or tapered in shape, and the fixed bearing portion (204) preferably having a central axial passage (234) extending therethrough.

4. 4. A blood pump as claimed in claim 1, further comprising two bearings (260, 263), each having a fixed bearing portion (204, 206) which extend axially into the impeller (203) at opposite axial ends of the impeller.

5. The blood pump according to any one of claims 1 to 4, wherein the fixed bearing portion is connected to the pump casing by a support structure (210, 410) having at least one opening (212, 412) to allow blood to pass therethrough in an axial direction, and the support structure has a size and shape such that it can guide the blood flow in a radial direction.

6. 6. The blood pump of claim 1, wherein the at least one blade is disposed on at least one of an outer surface of the impeller hub and an inner surface of the impeller hub, the at least one blade being disposed on the outer surface of the impeller hub and the blade extending axially beyond the hub.

7. The impeller (3, 103, 203, 603) has a blood flow passage (33, 133, 233) extending through a hub (36, 136) of the impeller (3, 103, 203, 603), and the impeller (3, 103, 203, 603) has at least one outer blade (31, 133, 233) disposed on an outer surface of the hub (36, 136) and having a size and shape capable of conveying blood from a blood flow inlet (21) to a blood flow outlet (22).

7. The blood pump of claim 1, further comprising at least one inner blade (32, 132, 232, 632) disposed within said passageway (33, 133, 233) and having a size and shape to convey blood through said passageway (33, 133, 233), said rotational bearing surface being formed on an exposed radially inner edge of at least one of said inner blade and said outer blade.

8. 8. The blood pump of claim 7, comprising two bearings (260, 263), each having a fixed bearing portion (204, 206), the fixed bearing portions extending axially within the impeller (203) at both axial ends of the impeller (203), the rotating bearing surface (265) of one of the bearings being formed on the exposed radially inner edge (251) of the at least one inner blade (232), and the rotating bearing surface (262) of the other of the bearings being formed on the exposed radially inner edge (250) of the at least one outer blade (231).

9. A blood pump as claimed in claim 7 or 8, wherein the passage (33, 133) of the impeller (3, 103) extends at least partially or entirely along the axis of rotation, and the at least one fixed bearing portion extends along at least half or at least ¾ of the length of the passage (33) of the impeller (3) or extends through the entire passage (33), and preferably the impeller (603) has at least one radial opening connecting the blood flow path with the environment of the impeller (603).

10. 10. The blood pump of claim 7, wherein the at least one blade is disposed on the impeller, the blade being divided by the hub of the impeller into an inner portion forming the inner blade and an outer portion forming the outer blade.

11. The pump casing (502) has a blood flow inlet (521) in a main direction of flow and a secondary blood flow inlet (523) axially spaced from the blood flow outlet (522), and the impeller (503) has at least two blades (531, 532), at least one of which is associated with the blood flow inlet (521) to transport blood from the blood flow inlet (521) to the blood flow outlet (522) in the main direction of flow, and at least the other of which is associated with the secondary blood flow inlet (523) to transport blood to the secondary blood flow outlet (522). A blood pump as described in any one of claims 1 to 10, wherein the at least two blades (531, 532) are arranged in axially opposite portions of the impeller adjacent an intermediate portion (530) for conveying blood from an inlet (523) to the blood flow outlet (521) in a direction opposite to the main direction of flow, and the at least one blade (532) associated with the secondary blood flow inlet (523) is preferably sized and shaped to convey blood along the intermediate portion (530) of the impeller (503).

12. The blood pump of any one of claims 1 to 11, wherein the bearing structure includes at least one of at least one ring (155) surrounding at least a portion of the fixed bearing portion (104) and at least one wing (153) engaging with at least a portion of the fixed bearing portion (104), and / or the rotating bearing surfaces (151, 152) are sized and shaped to engage with an axial end (142) of the fixed bearing portion (104).

13. 13. A blood pump as described in any one of claims 1 to 12, comprising an electric motor driving the impeller, a stator of the electric motor coupled to the pump casing and arranged circumferentially around the impeller, the stator of the electric motor including at least one electrical arrangement for generating a rotating magnetic field, and the impeller including at least one permanent magnet.

14. The blood pump according to any one of claims 1 to 13, wherein the fixed bearing portion (404) and the impeller (403) each comprise at least one magnet, the magnet (472) in the fixed bearing portion (404) and the magnet (472) in the impeller (403) are radially aligned and disposed in the fixed bearing portion (404) and the impeller (403), respectively, and an axial repulsive magnetic force is generated between the fixed bearing portion (404) and the impeller (403).

15. 15. A blood pump as claimed in any one of claims 1 to 14, wherein at least one of the fixed bearing surface and the rotating bearing surface comprises a material having a higher hardness than a material of the fixed bearing portion and the remainder of the impeller, respectively.

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