Blood pump

Abstract

The invention relates to an intravascular blood pump comprising a pumping device (11) having a pump housing (2) with a primary blood flow inlet (211) and a primary blood flow outlet (22) hydraulically connected by a primary blood flow passage (30), a primary impeller (31) having an upstream end and a downstream end configured to transport a primary blood flow (1BF) along the primary blood flow passage (30) from the primary blood flow inlet (211) to the primary blood flow outlet (22), a drive unit (4) configured to rotate the primary impeller (31) about a rotation axis (10), an impeller bearing (37) supporting the upstream end of the primary impeller (31), a central opening (262) extending axially through the impeller bearing (37), at least one secondary blood flow passage (321) in the primary impeller (31) having a secondary blood flow inlet (212) axially aligned with the central opening (262) of the impeller bearing (37) and each at least one secondary blood flow passage (321) having a secondary blood flow outlet (213), wherein the at least one secondary blood flow passage (321) is configured to transport a secondary blood flow (2BF) from the secondary blood flow inlet (212) to the secondary blood flow outlet (213), wherein the secondary blood flow outlet (213) connects the at least one secondary blood flow passage (321) to the primary blood flow passage (30) at a location axially located between the upstream end and the downstream end of the primary impeller (31).

Description

Technical Field

[0001] The present invention relates to an intravascular blood pump for supporting or replacing heart function by generating additional blood flow in a patient's blood vessels. Background Art

[0002] Different types of blood pumps are known, such as axial blood pumps, centrifugal blood pumps, and hybrid or diagonal blood pumps, in which blood flow is caused by a combination of axial and radial forces. Intravascular blood pumps are usually inserted percutaneously, for example, via the femoral artery into the left ventricle to bridge the aortic valve, or via the femoral vein into the right ventricle.

[0003] A rotary blood pump has an axis of rotation. In this patent application, the terms "radial" and "axial" refer to the axis of rotation, and respectively refer to "a radial direction relative to the axis of rotation" and "along the axis of rotation," respectively. The term "inner" refers to radially toward the axis of rotation, and the term "outer" refers to radially away from the axis of rotation.

[0004] An intravascular blood pump typically includes a pumping device as a main component. The pumping device comprises a pump portion, which includes a primary impeller for pumping blood from a blood inlet to a blood outlet, and a drive portion, which includes a motor for driving the primary impeller. The pump portion may include a flexibly bendable cannula positioned between the blood inlet and the blood outlet.

[0005] The pumping device comprises a pump part end portion, which is arranged on the pump side of the pumping device. The pumping device also comprises a drive part end portion, which is arranged on the drive side of the pumping device. The blood pump may further comprise a conduit connected to the pumping device in order to supply, for example, energy and / or a cleaning fluid to the pumping device. The conduit can be connected to the pump part end portion, but is mostly connected to the drive part end portion of the pumping device. It is also conceivable that the impeller is rotated forwards and backwards. Then, the blood flow inlet and the blood flow outlet of the pump part can be interchanged.

[0006] Typically, the impeller is supported within the pumping device via at least one impeller bearing. Various types of rotor bearings are known, such as plain bearings, in particular hydrodynamic plain bearings, pivot bearings, hydrostatic bearings, ball bearings, and combinations thereof. Contact bearings can be implemented as "blood-immersed bearings," in which the bearing surface comes into contact with the blood. Problems during operation can be friction and heat. If the bearing is immersed in blood, another problem can be blood clotting due to insufficient heating or cleaning.

[0007] WO 2017 / 021465 discloses an embodiment of a blood-cleaning radial sliding rotor bearing, which describes an intravascular blood pump comprising a generally cylindrical primary impeller and a generally cylindrical secondary impeller that rotate together. The secondary impeller is arranged at the radial center of the primary impeller. The secondary impeller blades extend toward the rotational axis of both impellers. The tips of the secondary impeller blades form the outer bearing surface of a sliding bearing. The cylindrical outer surface of a pin is positioned at the center of the secondary impeller, forming the inner bearing surface of the sliding bearing. In another embodiment, blood entering the center of the blood flow can enter the blood pump through a central axial channel in the impeller. In all embodiments, the primary and secondary impellers are mounted on a non-rotating central pin. This increases the hydraulic resistance to the secondary blood flow. Summary of the Invention

[0008] One of the objects of the present invention is to provide a blood pump that reduces the hydraulic resistance of the pumped blood.

[0009] This is achieved by the blood pump according to the invention and its preferred embodiments and further developments, as will be described in detail below.

[0010] According to a first aspect of the present invention, an intravascular blood pump includes a pumping device having a pump housing, which has a primary blood flow inlet and a primary blood flow outlet, which are hydraulically connected by a primary blood flow passage, wherein a primary impeller has an upstream end and a downstream end and is configured to convey a primary blood flow from the primary blood flow inlet to the primary blood flow outlet along the primary blood flow passage. The pumping device further includes a drive unit, which is configured to rotate the primary impeller about a rotation axis. An impeller bearing supports the upstream end of the primary impeller, wherein a central opening extends axially through the impeller bearing. The pumping device further includes at least one secondary blood flow passage in the primary impeller, the at least one secondary blood flow passage having a secondary blood flow inlet, which is axially aligned with the central opening of the impeller bearing. Each secondary blood flow passage has a secondary blood flow outlet and is configured to convey a secondary blood flow from the secondary blood flow inlet to the secondary blood flow outlet. The secondary blood flow outlet connects the at least one secondary blood flow passage to the primary blood flow passage at a location axially between the upstream and downstream ends of the primary impeller.

[0011] In other words, the secondary blood flow path extends obliquely through the primary impeller, starting from the remote center of the impeller and terminating at the lateral surface of the impeller, so that the secondary blood flow is obtained from the center of the blood flow, where the blood flow is fastest and has the greatest kinetic energy, and merges with and supports the primary blood flow in the primary blood flow path.

[0012] Since the secondary blood flow passage extends obliquely, the secondary blood flow passage also generates pressure in the secondary blood flow due to centrifugal force, making it easier for the blood pump to pump blood through the blood vessel.

[0013] Therefore, the secondary blood flow outlet is not arranged at the downstream end of the primary impeller. In this case, the secondary blood flow will mix with the primary blood flow downstream of the primary impeller. This will require a relatively long secondary blood flow path and increase hydraulic resistance.

[0014] Another advantage of this configuration is that there are no stationary parts along the secondary blood flow path. This reduces the hydraulic resistance of the blood pump.

[0015] The velocity of the blood can be utilized since, according to the prior art, the blood is not decelerated by the stationary pin bearing.

[0016] The one or more secondary blood flow channels can be considered to constitute a secondary impeller within the primary impeller. The primary and secondary impellers rotate together. The secondary impeller can be fully or partially implemented as an insert component in the tip of the primary impeller.

[0017] Preferably, at least a portion of the secondary impeller is disposed within the central opening. Then, incoming blood can be immediately conveyed by the secondary impeller. The impeller bearing can be disposed at the outer circumference of the secondary impeller.

[0018] The central opening can define an outer impeller bearing surface of the impeller bearing. Within the central opening, a portion of the primary or secondary impeller can be configured to form a corresponding inner impeller bearing surface. Preferably, at least one secondary blood flow passage extends into the central opening. For example, the inner impeller bearing surface can be formed by the outer circumference of one or more secondary impeller blades defined by the secondary blood flow passage.

[0019] However, it is also possible to arrange the inner impeller bearing surface on the outer circumference of a portion of the primary impeller (instead of the secondary impeller). This portion can be arranged in the central opening.

[0020] Preferably, the primary blood flow inlet is separated from the secondary blood flow inlet by an inflow separator. The inflow separator is preferably in the form of a ring. Thus, blood arriving at the blood pump is divided into blood flowing into the primary blood flow inlet or into the secondary blood flow inlet. Preferably, the inflow separator is in a stationary state. The inflow separator can then form an outer impeller bearing surface of the impeller bearing. Alternatively, the outer surface of the inflow separator can form an inner impeller bearing surface of the impeller bearing. The impeller bearing radially supports the primary impeller. The primary impeller can be mounted on the impeller bearing by the secondary impeller or a part thereof.

[0021] The inflow separator may include an additional impeller bearing ring as a separate component. The impeller bearing ring may form the outer or inner impeller bearing surface of the impeller bearing, but is preferably arranged inside the inflow separator to form an inner impeller bearing surface. The impeller bearing ring may be made of a different material than the inflow separator. In particular, the impeller bearing ring may be made of a ceramic material, in particular silicon carbide.

[0022] The inflow separator may be supported by at least one strut connecting the inflow separator to the pump housing. Preferably, at least three struts are provided. The struts may extend across the primary blood flow inlet. Preferably, the struts have low hydraulic resistance.

[0023] The inflow separator preferably includes at least one notch at the downstream end of the inflow separator. Preferably, the circumferential width of the notch is comparable to the circumferential width of a secondary blood flow path. Thus, the rotational position of the primary impeller can be defined by at least one secondary blood flow path extending into the notch and matching its circumferential position. Blood clots that begin to accumulate on the inner (or outer) impeller bearing surface are then removed by the edge of the notch as the inner (or outer) impeller bearing surface rotates past it. If the corresponding outer (or inner) impeller bearing surface is discontinuous, such as at the blade tips defined by the secondary impeller's second blood flow path, the outer (or inner) impeller bearing surface of the inflow separator can be cleaned similarly by the blade edges. Another advantage of the notch is that the clean edges of the notch can be cleaned by blood flow through the notch, preventing the accumulation of blood clots or debris. The inner or outer impeller bearing surface formed by the primary or secondary impeller preferably axially overlaps the notch to clean the entire impeller bearing surface of the primary or secondary impeller. Preferably, the outer impeller bearing surface of the inflow separator preferably axially overlaps with the secondary impeller blade tip surface (forming the inner impeller bearing surface), so that the entire outer impeller bearing surface is cleaned. Preferably, the axial length of the secondary impeller blade tip is greater than the circumferential length of the cutout. Preferably, at least one cutout extends between two struts.

[0024] Preferably, the cutout is not only arranged in the inflow separator, but also extends through the optionally present impeller bearing ring.Then, the cutout is completely open on both sides so that the cutout can be effectively cleaned.

[0025] The impeller bearing may be a plain bearing. Preferably, the impeller bearing is a blood-washed plain bearing. This has the advantage that the blood in the bloodstream can be used to wash the bearing and thereby cool the bearing.

[0026] Preferably, the mathematical center of the primary blood flow inlet, meaning the center of a specific region, is located within the secondary blood flow inlet. The primary blood flow inlet is arranged around the secondary blood flow inlet so that the middle portion of the blood flow entering the blood pump passes through the secondary blood flow inlet and enters the blood pump. The middle layer of blood flow has the highest velocity and is therefore provided to the secondary blood flow.

[0027] After passing through the primary and secondary blood flow inlets, blood enters the primary impeller and secondary impeller at the primary and secondary channel inlets, respectively, and enters the primary and secondary blood flow channels. Preferably, at least one secondary channel inlet is positioned at one of the rotational axes. Typically, the tip of an impeller does not have a reasonable velocity, which can cause blood to clot due to adhesion and may accumulate on stationary solid tips. However, using the proposed configuration, the middle portion of the blood flow flows into the secondary blood flow channel inlet. Therefore, blood clotting does not occur.

[0028] The secondary channel inlet is preferably arranged upstream of the primary channel inlet.One end of the secondary impeller can then be arranged inside the impeller bearing.

[0029] The primary impeller includes at least one blade having a primary pitch at its upstream end and a secondary blood flow passage having a secondary pitch that is similar to or identical to the primary pitch. The pitches are offset from each other by a maximum possible angle to prevent undesirable flow conditions, such as turbulence.

[0030] Preferably, at least two of the at least one secondary blood flow passages are asymmetrically arranged relative to the rotation axis, which enables a secondary channel inlet to be arranged on the rotation axis.

[0031] Preferably, the two secondary blood flow channels are arranged opposite each other with respect to the rotation axis, which makes a compact design of the secondary impeller possible.

[0032] Preferably, as already mentioned, a secondary blood flow passage defines a rim which moves over the outer impeller bearing surface as the secondary impeller rotates to clean the outer impeller bearing surface. The rim can be used as a scraper for the outer impeller bearing surface, in this way removing blood clots or debris.

[0033] As described above, the primary impeller may include an insert having at least one secondary blood flow passage formed therein. The secondary impeller may then be made of a different material than the primary impeller. For example, the secondary impeller may be made of a ceramic material. This may provide advantages for the inner impeller bearing surface. The primary and secondary impellers may optionally be integrally formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The foregoing summary of the preferred embodiments, as well as the following detailed description, will be better understood when read in conjunction with the accompanying drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the accompanying drawings. In the drawings:

[0035] Figure 1 is a cross-sectional view of a first embodiment of a blood pump according to the present invention;

[0036] Figure 2 for Figure 1 A part of the pump is shown in FIG.

[0037] Figure 3 for Figure 1 A part of the drive part is shown in FIG.

[0038] Figure 4 is a perspective view toward the end of the pump portion of a first embodiment of a blood pump;

[0039] Figure 5 In essence Figure 4 's view, but with a transparent pump housing;

[0040] Figure 6 In essence, Figure 5 The same view, but showing a second embodiment of the blood pump;

[0041] Figure 7 is a perspective view of an embodiment of a two-stage impeller;

[0042] Figure 8 is a perspective view of a separator ring of a first embodiment of a blood pump;

[0043] Figure 9 is a perspective view of a separator ring of a second embodiment of a blood pump;

[0044] Figure 10 a cross-section of the end of the drive portion of a blood pump showing the auxiliary impeller is shown in perspective;

[0045] Figure 11A A perspective view of the auxiliary impeller and rotor bearing ring;

[0046] Figure 11B is a perspective view of a rotor bearing ring having a cutout; and

[0047] Figure 12 A perspective view of a three-stage impeller according to the first or second embodiment. DETAILED DESCRIPTION

[0048] exist Figure 1 , a cross-sectional view of a first embodiment of an intravascular blood pump is shown. Rotating parts are not shown cut away. The intravascular blood pump 1 comprises a pumping device 11 and a supply line in the form of a catheter 5 attached thereto.

[0049] The pumping device 11 comprises a substantially cylindrical pump housing 2 at least in its middle portion. The pump housing 2 comprises a blood flow inlet 21 and a blood flow outlet 22. Figure 1 In FIG. 1 , the pump housing 2 appears to comprise two separate parts, but these parts are integral or connected into one piece.

[0050] As in Figure 2 The pump section is shown in an enlarged representation and in Figure 4 and 5 As can be better seen in the front perspective view shown, the blood flow inlet 21 includes a primary blood flow inlet 211 and a secondary blood flow inlet 212. The primary blood flow inlet 211 surrounds the secondary blood flow inlet 212. The primary blood flow inlet 211 and the secondary blood flow inlet 212 are separated by an inflow separator 26. Inside the inflow separator 26, the inflow separator 26 includes an impeller bearing ring 27, which is located at the bottom of the inflow separator 26. Figure 8 Furthermore, the pumping device 11 comprises a primary impeller 31, into which a secondary impeller 32 is integrated. The primary and secondary impellers 31, 32 can rotate together around the axis of rotation 10. The secondary impeller 32 can be as shown. Figure 7 The secondary impeller 31 is shown in the form of an inlay and can be arranged inside the secondary impeller cavity 312 of the primary impeller 31. The secondary impeller cavity 312 is open towards the pump part end PSE of the pumping device 11. Alternatively, the primary impeller 31 and the secondary impeller 32 are formed integrally.

[0051] The primary blood flow 1BF flows from the primary blood flow inlet 211 to the primary impeller 31 outside the inflow separator 26, and is further transported by the primary impeller 31 through the primary blood flow passage 30 to the primary blood flow outlet 22. The secondary blood flow 2BF flows from the secondary blood flow inlet 212 through the inflow separator 26 to the secondary impeller 32, and is further transported by the secondary impeller 32 through multiple secondary blood flow passages 321 to the primary blood flow passage 30.

[0052] Thus, the blood flow reaching the pumping device 11 at the end of the pump portion, preferably approximately almost the entire cross-section of the pumping device 11, can flow into the primary and secondary blood inlets 211, 212 without significant deflection. Due to the central position of the secondary blood inlet 212, blood from the middle of the blood flow can also enter the pumping device 11 without deflection. This is advantageous because blood flow is generally laminar, in which the flow velocity is greatest in the center.

[0053] The primary impeller 31 includes primary impeller blades 313 extending into the primary blood flow channel 30, with primary impeller channels 311 disposed between the blades 313. The primary impeller channels 311 have a primary pitch at a primary channel inlet 314 at each end of the primary impeller channels 311 facing the pump section end portion PSE. The secondary impeller 32 includes at least one, and preferably two, secondary blood flow channels 321, hereinafter also referred to as secondary impeller channels 321. The secondary impeller channels 321 have a secondary pitch at a secondary channel inlet 324 disposed upstream of the secondary impeller channels 321. The secondary pitch is preferably the same as the primary pitch, but may differ to some extent as long as undesirable flow conditions, such as turbulence, can be prevented. At the end of the secondary impeller 32 facing the drive section end portion DSE, a connecting through-opening 315 is provided between the secondary impeller chamber 312 and one of the primary impeller channels 311. One end of the through opening 315 in the direction of blood flow defines a secondary blood flow outlet 213. The secondary blood flow outlet 213 is further arranged radially outward relative to the rotation axis 10. Therefore, the centrifugal force generated by the rotation of the secondary impeller 32 pushes the blood outward in the radial direction. In this way, the secondary blood flow 2BF is transported through the secondary blood flow inlet 212, and further passes through the secondary impeller channel 321 of the secondary impeller 32, and merges with the primary blood flow 1BF flowing through the primary impeller channel 311 of the primary impeller 31. In this way, the pumped blood flow PBF is formed. The pumped blood flow PBF leaves the pumping device 11 at the blood flow outlet 22.

[0054] The primary and secondary impellers 31 and 32 are mounted together in an impeller bearing 37. They are connected or integrated into a single component via a secondary impeller cavity 312. The inflow separator 26 includes an impeller bearing ring 27 disposed within the inflow separator 26. An outer impeller bearing surface 277 of the impeller bearing 37 is disposed within the impeller bearing ring 27. The impeller bearing 37 also includes an inner impeller bearing surface 327 disposed on the outer circumference of the secondary impeller 32.

[0055] The primary impeller 31 is fixedly connected to a tapered portion 314 leading to the blood flow outlet 22. The tapered portion 314 guides the pumped blood flow PBF in a radially outward direction relative to the rotation axis 10. The blood then reaches the blood flow outlet 22.

[0056] From the tapered portion 314 toward the pump section end PSE, the drive section 4 is located within the pump housing 2 of the pumping device 11. This drive section 4 includes a stator 40 and a rotor 41. An axial gap 401 is provided between the stator 40 and the rotor 41. To cool the stator 40 and the rotor 41, the axial gap 401 is cleaned with blood. To this end, an auxiliary blood flow ABF enters the drive section 4 through the auxiliary blood flow inlet 23 provided at the drive section end DSE. The blood is then conveyed by the auxiliary impeller 42 through the auxiliary pump gap 423 provided between the auxiliary impeller 42 and the inner wall of the pump housing 2. From there, the blood continues to flow into the axial gap 401. From the axial gap 401, the auxiliary blood flow ABF enters the radial gap 241. An auxiliary blood flow outlet 24 is provided at the radially outer end of the radial gap 241. The auxiliary blood flow ABF flows in the axial gap 401 in a direction opposite to the pumping direction of the primary and secondary impellers 31 and 32. The auxiliary blood flow ABF in the drive section 4 also flows substantially in the opposite direction to the general blood flow GBF flowing around the blood pump 1 .

[0057] Reference Figure 3 As can be better seen in the enlarged view shown, the rotor bearing ring 43 surrounds the auxiliary impeller 42. The auxiliary impeller 42 includes auxiliary impeller blades 421. The auxiliary impeller blades 421 project in the direction of the rotation axis 10, toward the drive section end DSE of the pumping device 11. A radial rotor bearing 47 is provided at the drive section end DSE and includes an outer rotor bearing surface 4211 and an inner rotor bearing surface 4311, with an axially extending bearing gap defined therebetween. The outer rotor bearing surface 4311 is provided on the rotor bearing ring 43. Blood transported by the auxiliary impeller 42 flows through the bearing gap and further into the axial gap 401 between the rotor 41 and the stator 40. From the axial gap 401, the blood flows into the radial gap 241. The radial gap 241 extends between the tapered portion 314 of the primary impeller 31 and the stator 40. The auxiliary blood outflow port 24 is provided at the transition between the radial gap 241 and the periphery of the pumping device 11. The auxiliary blood outflow port 24 is disposed perpendicular to the rotation axis 10. Here, blood from the auxiliary blood flow ABF merges with the pumped blood flow PBF and the surrounding general blood flow GBF from the pump portion 3. As shown in the figure, when the auxiliary blood flow outlet 24 is located close to the outer diameter of the pump housing 2 and close to the primary blood flow outlet 22, the pumped blood flow PBF and the general blood flow GBF support the extraction of blood from the radial gap 241 due to their flow rates. This enhances the auxiliary blood flow ABF through the axial gap 401.

[0058] The rotation axis 10 extends through the center of the auxiliary impeller 42, and a protrusion 422 is provided on the side of the auxiliary impeller 42 opposite the rotor 41. A bearing pin 44 is provided in the direction of the rotation axis 10 toward the drive section end DSE and adjacent to the protrusion 422. The bearing pin 44 is connected to the pump housing 2. The axial bearing surface of the bearing pin 44 facing the auxiliary impeller 42 has a convex shape. The rotation axis 10 passes through the apex of the axial bearing surface of the bearing pin 44 and the apex of the axial bearing surface of the protrusion 422. In this way, the bearing pin 44 and the protrusion 422 interact and form a thrust bearing to transmit axial forces about the rotation axis between the protrusion 422 and the bearing pin 44, wherein the aforementioned parts are rotatable relative to each other. Obviously, the smaller the contact surface, the lower the rotational friction.

[0059] The end portion of the driving portion of the blood pump 1 includes one or more, preferably three, auxiliary inlet holes 231. The auxiliary inlet holes 231 extend from the auxiliary blood flow inlet 23 to the auxiliary impeller chamber 232, in which the auxiliary impeller 42 is disposed. Thus, blood flows from the auxiliary blood flow inlet 23 to the auxiliary impeller 42 via the auxiliary inlet holes 231.

[0060] At least one line through-hole 25 is provided at the drive section end DSE of the pumping device 11. The line through-hole 25 can extend from the catheter 5 to the stator 40. Preferably, three line through-holes 25 are provided around the rotation axis 10. One line through-hole 25 can be provided between the two auxiliary inlet through-holes 231. At least one supply line 51, 52, and / or 53 can extend through the line through-hole 25 to connect to the stator 40. Preferably, as shown in the figure, the supply line 51, 52, and / or 53 extends through the interior of the catheter 5 to the outside of the patient's body. The supply line 51, 52, and / or 53 extends from the catheter 5 to the stator 40 without contacting the blood.

[0061] Figure 4 A front perspective view of the pump section end portion (PSE) of the pump section 3 is shown. As shown, the secondary impeller 32 is disposed within the impeller bearing ring 27. The impeller bearing ring 27 is disposed within the inflow separator 26. Alternatively, the additional impeller bearing ring 27 can be omitted, so that the outer impeller bearing surface 277 is formed by the inflow separator 26. Here, the inflow separator 26 is mounted between the primary blood flow 1BF and the secondary blood flow 2BF via three struts 28. The secondary blood flow 2BF is shown flowing into the secondary impeller 32 through the secondary blood flow inlet 212, which is configured to flow into the impeller bearing ring 27. In the secondary impeller 32, blood flows along the secondary impeller channel 321 and through the through-opening 315 to the secondary blood flow outlet 213. Here, the secondary blood flow 2BF merges with the primary blood flow 1BF to form the pumped blood flow PBF.

[0062] Figure 5 The pump section end PSE of the pump section 3 is shown in a perspective view, wherein the pump housing 2 is shown in a transparent manner. It can be seen that the through-opening 315 and the secondary blood flow outlet 213 are arranged between the two primary impeller blades 313. As shown in the figure, the pillars 28 are connected by an outer pillar connecting ring 29. The pillar connecting ring 29 is arranged in the inner circumference of the pump housing 2 at the pump section end PSE. The impeller bearing ring 27 is supported by the pillars 28. It is conceivable that the pillar connecting ring 29 and the pillars 28 are manufactured as a whole. Preferably, the impeller bearing ring 27 is also part of this component. Said component can also be formed in one piece with the pump housing 2.

[0063] Figure 6 A perspective view of the pump section end PSE of the pump section 3 is shown, wherein the pump section 3 is shown in a transparent manner. Figures 3 to 5 In the illustrated embodiment, the pump housing 2 differs from the embodiment shown, in that the inflow separator 26 comprises at least one cutout 261, preferably three cutouts 261, at the downstream end of the inflow separator 26. The cutout 261 is arranged between the two struts 28. The impeller bearing ring 27 is part of the inflow separator 26 or is fixedly connected thereto, and the cutout 261 also extends through the impeller bearing ring 27. When the secondary impeller rotates, the cross section of the secondary impeller channel 321 increases when it is aligned with the cutout 261. The secondary impeller 32 extends within the impeller bearing ring 27 in a direction towards the pump section end PSE to a maximum extent at one end of the cutout 261. This has the following effect: in operation, due to the mating portion of the rotation axis towards the thrust, the edge of the cutout 261 extends on the impeller inner bearing surface 327 and removes blood clots at the beginning of their formation, or preferably prevents the formation of blood clots, because the mating portion of the rotation axis towards the thrust bearing surface 328 is in direct blood contact at the cutout 261. This helps to avoid blood stagnation in the axial thrust bearing. Figure 7 As shown, the inner impeller bearing surface 327 also has an edge 325 that has the function of removing blood clots from the outer impeller bearing surface 277.

[0064] Figure 7The secondary impeller 32 is shown in detail in a perspective view. Here, the secondary impeller 32 is configured as an insert and has a generally cylindrical form. It can be made of a different material than the primary impeller 31, for example, a ceramic material. The insert includes a cylindrical portion 323 disposed within the secondary impeller cavity 312 of the primary impeller 21. A circumferential protrusion 329 forms an axial stop for the secondary impeller 32 within the secondary impeller cavity 312. An inner impeller bearing surface 327 is provided on the outer circumference of the secondary impeller 32. Two secondary impeller channels 321 are provided at the end of the secondary impeller 32 facing the pump section end (PSE). The secondary impeller channels 321 have the largest cross-section at the upstream end of the secondary impeller 32. Therefore, the cross-section of the secondary impeller channels 321 decreases as they move away from the blood flow inlet 21. Here, as blood flows through the secondary impeller channels 321, it is directed from the primary axial direction to the axial-radial direction.

[0065] The secondary impeller channel 321 is arranged asymmetrically with respect to the rotation axis 10 of the secondary impeller 32. At the end of the secondary impeller 32 that faces the blood flow inlet 21, the rotation axis 10 extends through one of the secondary impeller channels 321. Here, the center of rotation, located on the rotation axis 10, does not coincide with the solid portion of the secondary impeller 32. This has the advantage of allowing blood to pool at the center of rotation, preventing a velocity difference with the surrounding blood flow.

[0066] An edge 325 is provided at the transition between the secondary impeller channel 321 and the inner impeller bearing surface 327. As described above, this edge 325 serves to dislodge blood clots from forming on the outer impeller bearing surface 277. The inner impeller bearing surface 327 provides the inner surface of a radial bearing at the pump section end PSE. The secondary impeller 32 also includes an axial impeller bearing surface 328. This is provided on a circumferential protrusion 329. The axial impeller bearing surface 328 forms part of the aforementioned axial stop or axial thrust bearing. The axial stop can be configured as an axial bearing capable of transmitting force from the secondary impeller 32 to the bearing ring 27 during impeller rotation.

[0067] Figure 8 An enlarged view of the impeller bearing ring 27 is shown. An outer impeller bearing surface 277 is disposed within the interior of the impeller bearing ring 27. The impeller bearing ring 27 includes an axial bearing ring surface 278. As shown, the axial bearing ring surface 278 may be disposed at an axial end of the impeller bearing ring 27.

[0068] Figure 9 A perspective view of an impeller bearing ring 27 according to another embodiment is shown. Figure 8 The embodiment shown differs in that it includes cutouts 261, which, as previously described, are provided at the downstream end of the impeller bearing ring 27. The number of cutouts 261 preferably matches the number of struts 28.

[0069] Figure 10 A perspective cross-sectional view through the drive section end DSE of the drive section 4 is shown. As shown, the auxiliary blood flow ABF enters the pump housing 2 at the auxiliary blood flow inlet 23. The auxiliary impeller 42 accelerates the blood, which continues to flow into the axial gap 401. As indicated by the arrows ABF within the axial gap 401, the blood does not flow directly in the direction of the rotation axis 10, but rather has a strong circumferential flow component, causing the blood to flow helically along the axial gap 401.

[0070] FIG11 shows a perspective view of the end of the rotor 41 at the drive section end DSE of the pumping device 11. The auxiliary impeller blades 421 of the auxiliary impeller 42 can be clearly identified, and they extend straight in the radial direction. The auxiliary impeller blades 421 provide an inner rotor bearing surface 4211 of the radial rotor bearing 47 on their outer circumference. In addition, each of the auxiliary impeller blades 421 has a chamfer 4212. This chamfer 4212 facilitates the formation of the radial rotor bearing 47. Figure 10 The tapered drive section end DSE of the pumping device 11 is shown. In addition, the auxiliary impeller blade 421 includes a radially extending end surface 4214 at the axial end of the auxiliary impeller 42. A ridge 422 is formed at the center of the axial end of the auxiliary impeller 42. The ridge 422 interacts with the bearing pin 44, as shown in FIG. Figure 10 shown.

[0071] Figure 11A Also shown is a rotor bearing ring 43, which is arranged around the inner rotor bearing surface 4211 of the auxiliary impeller 42. The outer rotor bearing surface 4311 of the rotor bearing ring 43 forms a rotor bearing 47 together with the inner rotor bearing surface 4211 of the auxiliary impeller 42. The auxiliary impeller 42 has an axial length L and a diameter D. Alternatively, as Figure 11B As shown, the rotor bearing ring 43 may have a cutout that is similar in shape, function, and arrangement to the cutout 261 of the impeller bearing ring 27 described above.

[0072] Figure 12 One end of the rotor 41 is shown in perspective, connected to the tapered portion 314 of the primary impeller 31. The tertiary impeller 242 is disposed between the tapered portion 314 and the pump portion end of the rotor 41 and extends radially from the outer diameter of the rotor 41 to the outer diameter of the tapered portion 314 to form a shoulder. The axial plane of this shoulder forms the rotatable wall 2411 of the radial gap 24. Tertiary impeller blades 2412 project from the rotatable wall 2411 toward the drive portion end DSE of the pumping device 11. Preferably, the tertiary impeller blades 2412 extend axially along the axis of rotation 10. In particular, the tertiary impeller blades 2412 are straight and extend in a radial direction relative to the axis of rotation 10. Furthermore, in an alternative embodiment, the tertiary impeller blades 2412 may be omitted.

Claims

1. An intravascular blood pump comprising a pumping device (11) having: The pump housing (2) has a primary blood flow inlet (211) and a primary blood flow outlet (22) hydraulically connected by a primary blood flow passage (30), A primary impeller (31) having an upstream end and a downstream end, configured to convey the primary blood flow (1BF) from the primary blood flow inlet (211) to the primary blood flow outlet (22) along the primary blood flow passage (30), a drive unit (4) configured to rotate the primary impeller (31) about a rotation axis (10), an impeller bearing (37) supporting the upstream end of the primary impeller (31), a central opening (262) extending axially through the impeller bearing (37), at least one secondary blood flow passage (321) in the primary impeller (31), the at least one secondary blood flow passage (321) having a secondary blood flow inlet (212) axially aligned with the central opening (262) of the impeller bearing (37), and each of the at least one secondary blood flow passage (321) having a secondary blood flow outlet (213), wherein the at least one secondary blood flow passage (321) is configured to convey a secondary blood flow (2BF) from the secondary blood flow inlet (212) to the secondary blood flow outlet (213), The secondary blood flow outlet (213) connects at least one of the secondary blood flow passages (321) to the primary blood flow passage (30) at a position axially located between the upstream end and the downstream end of the primary impeller (31).

2. The intravascular blood pump of claim 1, wherein the central opening (262) defines an outer impeller bearing surface (277) of the impeller bearing (37) by which the primary impeller (31) is rotatably supported.

3. An intravascular blood pump as described in claim 2, wherein the primary blood flow inlet (211) is separated from the secondary blood flow inlet (212) by a non-rotating inflow separator (26), and the inflow separator (26) forms the outer impeller bearing surface (277) of the impeller bearing (37).

4. Intravascular blood pump according to claim 3, wherein the inflow separator (26) comprises an impeller bearing ring (27) as a separating component, while forming the outer impeller bearing surface (277) of the impeller bearing (37).

5. An intravascular blood pump as claimed in claim 3 or 4, wherein the inflow separator (26) is supported by at least one strut (28) extending across the primary blood flow inlet (211).

6. Intravascular blood pump according to claim 5, wherein at least one of the struts (28) connects the inflow separator (26) to the pump housing (2).

7. The intravascular blood pump of claim 3 or 4, wherein the inflow separator (26) comprises at least one cutout (261) at a downstream end of the inflow separator (26).

8. Intravascular blood pump according to claim 3 or 4, wherein the inflow separator (26) has at least one cutout (261) in the outer impeller bearing surface (277).

9. An intravascular blood pump as described in any one of claims 2 to 4, wherein one or more of at least one of the secondary blood flow passages (321) are defined by an edge (325) that moves on the outer impeller bearing surface (277) when the primary impeller (31) rotates to clean the outer impeller bearing surface (277).

10. The intravascular blood pump according to any one of claims 1 to 4, wherein the impeller bearing (37) is a sliding bearing.

11. Intravascular blood pump according to claim 10, wherein the impeller bearing (37) is a blood-washing sliding bearing.

12. The intravascular blood pump according to any one of claims 1 to 4, wherein the center of the area of ​​the primary blood flow inlet (211) is arranged in a separate secondary blood flow inlet (212).

13. The intravascular blood pump according to any one of claims 1 to 4, wherein a secondary blood flow inlet (212) of at least one of the secondary blood flow passages (321) is arranged at the position of the rotation axis (10).

14. An intravascular blood pump as claimed in any one of claims 1 to 4, wherein a secondary channel inlet (324) forming a part of at least one of the secondary blood flow passages (321) is arranged upstream of a primary channel inlet (314) forming a part of the primary impeller channel (311) in the primary blood flow passage (30).

15. An intravascular blood pump as claimed in any one of claims 1 to 4, wherein the primary impeller (31) includes at least one blade (313) having a primary pitch at an upstream end of the primary impeller (31), and wherein the at least one secondary blood flow channel (321) has a secondary pitch that is similar to or identical to the primary pitch.

16. The intravascular blood pump according to any one of claims 1 to 4, wherein exactly one of at least one of the secondary blood flow channels (321) has an upstream end arranged at the position of the rotation axis (10).

17. The intravascular blood pump according to any one of claims 1 to 4, wherein at least two of at least one of the secondary blood flow channels (321) are arranged asymmetrically with respect to the rotation axis (10).

18. The intravascular blood pump according to any one of claims 1 to 4, wherein two of at least one of the secondary blood flow channels (321) are arranged opposite each other with respect to the rotation axis (10).

19. The intravascular blood pump of any one of claims 1 to 4, comprising exactly two of at least one said secondary blood flow path (321).

20. The intravascular blood pump of any one of claims 1 to 4, wherein the primary impeller (31) comprises an insert in which at least one of the secondary blood flow passages (321) is formed.

21. The intravascular blood pump of claim 5, wherein the inflow separator (26) is supported by three of the struts (28) extending across the primary blood flow inlet (211).

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