Blood pump

Abstract

The invention relates to an intravascular blood pump comprising a pumping device (11) having: a pump housing (2) having 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 upstream and downstream ends, a distal end and a transverse surface; a drive unit (4); an impeller bearing (37); 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) extending obliquely through the primary impeller (31), starting from a center at a secondary blood flow inlet (212) at a distal end of the primary impeller (31) and terminating at a transverse surface of the primary impeller (31), such that a secondary blood flow (2BF) is taken from the center to the blood flow, and the primary blood flow (1BF) is converged and supported in the primary blood flow passage (30).

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application entitled "Blood Pump", filed on March 22, 2021, with application number 202180025128.1, entering the Chinese national phase on September 27, 2022. Technical Field

[0003] This invention relates to an intravascular blood pump that supports or replaces heart function by generating additional blood flow in a patient's blood vessels. Background Technology

[0004] 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 both axial and radial forces. Intravascular blood pumps are typically 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.

[0005] The rotary blood pump has a rotation axis. In this patent application, the terms "radial" and "axial" refer to the axis of rotation, and respectively to "radial direction relative to the axis of rotation" and "along the axis of rotation". The term "inner" means radially toward the axis of rotation, and the term "outer" means radially away from the axis of rotation.

[0006] Intravascular blood pumps typically include a pumping device as the main component. This pumping device has a pump section and a drive section. The pump section includes a primary impeller for pumping blood from a blood inlet to a blood outlet, and the drive section includes a motor for driving the primary impeller. The pump section may include a flexible, bendable cannula located between the blood inlet and outlet.

[0007] The pumping device includes a pump portion end disposed on the pump side of the pumping device. The pumping device also includes a drive portion end disposed on the drive side of the pumping device. The blood pump may further include a conduit connected to the pumping device for supplying the pumping device with, for example, energy and / or a cleansing fluid. The conduit may be connected to the pump portion end, but most of it is connected to the drive portion end of the pumping device. It is also conceivable to rotate the impeller forward and backward. In this case, the blood inlet and blood outlet of the pump portion can be interchanged.

[0008] Typically, the impeller is supported within the pumping unit by at least one impeller bearing. Different types of rotor bearings are known, such as sliding bearings, particularly hydrodynamic sliding bearings, pivot bearings, hydrostatic bearings, ball bearings, etc., and combinations thereof. In particular, contact bearings can be implemented as "blood-immersed bearings," where the bearing surface is in contact with blood. Problems during operation may include friction and heat. If the bearing is immersed in blood, another problem may be blood clotting due to insufficient heating or cleaning.

[0009] WO 2017 / 021465 discloses an embodiment of a radial sliding rotor bearing for blood cleansing, describing 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 blades of the secondary impeller extend toward the rotational axes 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 disposed at the center of the secondary impeller, forming the inner bearing surface of the sliding bearing. In another embodiment, blood reaching the center of the blood flow enters the blood pump through a central axial channel in the impeller. In all specific embodiments, the primary and secondary impellers are mounted on a non-rotating central pin. This increases the hydraulic resistance of the secondary blood flow. Summary of the Invention

[0010] One of the objectives of this invention is to provide a blood pump that reduces the hydraulic resistance of the pumped blood.

[0011] This is achieved by the blood pump of the present invention, its preferred embodiments, and further developments, as will be described in detail below.

[0012] According to a first aspect of the invention, an intravascular blood pump includes a pumping device having a pump housing, having a primary blood inlet and a primary blood outlet, hydraulically connected by a primary blood flow path, wherein a primary impeller has an upstream end and a downstream end and is configured to deliver a primary blood flow from the primary blood inlet to the primary blood outlet along the primary blood flow path. The pumping device further includes a drive unit 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 path in the primary impeller, the at least one secondary blood flow path having a secondary blood inlet axially aligned with the central opening of the impeller bearing. Each secondary blood flow path has a secondary blood outlet and is configured to deliver a secondary blood flow from the secondary blood inlet to the secondary blood outlet. The secondary blood flow outlet is located axially between the upstream and downstream ends of the primary impeller, connecting at least one secondary blood flow path to the primary blood flow path.

[0013] In other words, the secondary blood flow path extends obliquely through the primary impeller, starting from the center at the distal end of the impeller and ending at the transverse surface of the impeller, so that the secondary blood flow is obtained from the center of the incoming blood flow, where the blood flow is the fastest and has the greatest kinetic energy, and merges with and supports the primary blood flow in the primary blood flow path.

[0014] Because this secondary blood flow pathway extends obliquely, it also generates pressure within the secondary blood flow due to centrifugal force. Therefore, it is easier for the blood pump to deliver blood through this vessel.

[0015] Therefore, the secondary blood flow outlet is not located downstream 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 considerably long secondary blood flow path and increase hydraulic resistance.

[0016] Another advantage of this design is that there are no stationary parts along the secondary blood flow path. This reduces the hydraulic resistance of the blood pump.

[0017] The speed of blood can be utilized because, according to current technology, the blood does not slow down due to a stationary pin bearing.

[0018] The one or more secondary blood flow paths can be considered as constituting 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 embedded component in the tip of the primary impeller.

[0019] Preferably, at least a portion of the secondary impeller is disposed within the central opening. The arriving blood can then be immediately delivered by the secondary impeller. The impeller bearing can be disposed on the outer circumference of the secondary impeller.

[0020] The central opening defines the outer impeller bearing surface of the impeller bearing. Within this 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 path 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 path.

[0021] However, it is also possible to position the inner impeller bearing surface on the outer circumference of a portion of the primary impeller (rather than the secondary impeller). This portion may be positioned within the central opening.

[0022] Preferably, the primary blood inlet is separated from the secondary blood inlet by an inflow separator. The inflow separator is preferably in the form of a ring. Therefore, blood arriving at the blood pump is divided into flowing into the primary blood inlet or the secondary blood inlet. Preferably, the inflow separator is stationary. The inflow separator can then form the outer impeller bearing surface of the impeller bearing. Alternatively, the outer surface of the inflow separator can form the 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 portion thereof.

[0023] The inflow separator may include an additional impeller bearing ring as a separate component. This impeller bearing ring may form the outer or inner impeller bearing surface of the impeller bearing, but is preferably disposed 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, especially silicon carbide.

[0024] The inflow separator may be supported by at least one support pillar connecting the inflow separator to the pump housing. Preferably, at least three supports are provided. The support pillar may extend across the primary blood inlet. Preferably, the support pillar has low hydraulic resistance.

[0025] The inflow separator preferably includes at least one slit at the flow end of the inflow separator. Preferably, the circumferential width of the slit 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 slit and matching its circumferential position. Blood clots that begin to accumulate on the inner (or outer) impeller bearing surface are then cleared by the edge of the slit as the inner (or outer) impeller bearing surface rotates past it. If the corresponding outer (or inner) impeller bearing surface is discontinuous, such as the blade tip defined by the second blood flow path of the secondary impeller, the outer (or inner) impeller bearing surface of the inflow separator can be cleaned by similar means through this blade edge. Another advantage of the slit is that the clean edge of the slit can be washed by the blood flow passing through it, thus preventing the accumulation of blood clots or debris. The inner or outer impeller bearing surface formed by the primary or secondary impeller preferably covers the slit axially to clean the entire impeller bearing surface of the primary or secondary impeller. Preferably, the outer impeller bearing surface flowing into the separator axially overlaps with the end surface of the secondary impeller blade (forming the inner impeller bearing surface), thereby cleaning the entire outer impeller bearing surface. Preferably, the axial length of the tip of the secondary impeller blade is greater than the circumferential length of the cut. Preferably, at least one cut extends between the two supports.

[0026] Preferably, the cut is not only disposed in the inflow separator, but also extends through the previously described impeller bearing ring, which may be present. The cut is then fully opened on both sides to allow for effective cleaning.

[0027] The impeller bearing can be a sliding bearing. Preferably, the impeller bearing is a blood-washing sliding bearing. This has the advantage that the blood in the blood flow can be used to wash the bearing and thereby cool it.

[0028] Preferably, the mathematically defined area 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 such that the middle portion of the blood flow arriving at the blood pump passes through the secondary blood flow inlet and enters the blood pump. This middle layer of blood flow has the highest speed and is therefore supplied to the secondary blood flow.

[0029] After passing through the primary and secondary blood flow inlets, blood enters the primary and secondary impellers at the primary and secondary channel inlets, respectively, and thus enters the primary and secondary blood flow paths. Preferably, at least one primary and secondary channel inlet is positioned on one of the axes of rotation. Normally, the tip of an impeller does not have a reasonable velocity that could cause blood to coagulate due to adhesion, and accumulation may occur on the stationary solid tip. However, with the proposed configuration, the middle portion of the blood flow flows into the inlet of the secondary blood flow path. Therefore, blood coagulation does not occur.

[0030] The secondary channel inlet is preferably located upstream of the primary channel inlet. Then, one end of the secondary impeller can be positioned inside the impeller bearing.

[0031] The primary impeller includes at least one blade with a primary pitch and a secondary blood flow path with a secondary pitch that is approximately or identical to the primary pitch at its upstream end. These pitches are offset from each other by the maximum possible angle to prevent undesirable flow conditions, such as turbulence.

[0032] Preferably, at least two of the at least one secondary blood flow pathway are configured asymmetrically with respect to the axis of rotation. This allows for the configuration of primary and secondary channel inlets on the axis of rotation.

[0033] Preferably, the two secondary blood flow paths are arranged opposite each other relative to the axis of rotation. This makes a compact design of the secondary impeller possible.

[0034] Preferably, as already mentioned, a secondary blood flow path defines an edge that moves above the outer impeller bearing surface as the secondary impeller rotates to clean the outer impeller bearing surface. This edge can be used as a scraper for the outer impeller bearing surface, thereby removing blood clots or debris.

[0035] As described above, the primary impeller may include an insert in which at least one secondary blood flow path is formed. 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 is advantageous for the inner impeller bearing surface. The primary impeller and the secondary impeller may optionally be formed as a single unit. Attached Figure Description

[0036] The above overview and the following detailed description of the preferred embodiments will be better understood when read in conjunction with the accompanying drawings. However, the scope of this disclosure is not limited to the specific embodiments disclosed in the drawings. In the drawings:

[0037] Figure 1 This is a cross-sectional view of a first embodiment of the blood pump of the present invention;

[0038] Figure 2 for Figure 1 An enlarged view of a portion of the pump section;

[0039] Figure 3 for Figure 1 A magnified view of a portion of the drive section;

[0040] Figure 4 A perspective view of the pump portion end of a first embodiment of the blood pump;

[0041] Figure 5 In essence Figure 4 The view is shown, but with a transparent pump housing;

[0042] Figure 6 In essence, it is with Figure 5 Same view, but a second embodiment view of the blood pump;

[0043] Figure 7 A perspective view of an embodiment of a two-stage impeller;

[0044] Figure 8 A perspective view of the separator ring of a first embodiment of a blood pump;

[0045] Figure 9 A perspective view of the separator ring of a second embodiment of the blood pump;

[0046] Figure 10 A perspective view shows a cross-section of the end of the blood pump drive section, which reveals the auxiliary impeller;

[0047] Figure 11A Perspective view of the impeller and rotor bearing rings;

[0048] Figure 11B A perspective view of a rotor bearing ring with cutouts; and

[0049] Figure 12 A perspective view of the three-stage impeller of the first or second embodiment. Detailed Implementation

[0050] exist Figure 1 The figure shows a cross-sectional view of a first embodiment of an intravascular blood pump. Rotating parts are not shown cut open. The intravascular blood pump 1 includes a pumping device 11 and a supply line in the form of a catheter 5 attached thereto.

[0051] The pumping device 11 includes, at least in its intermediate portion, a substantially cylindrical pump housing 2. The pump housing 2 includes a blood inlet 21 and a blood outlet 22. Figure 1 In the image, the pump housing 2 appears to consist of two separate parts, but these parts are either integral or connected as one unit.

[0052] As in Figure 2 The enlarged display of the pump section shown, and in Figure 4 and 5 As can be better seen in the front perspective view shown, 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... Figure 8The following are shown separately. Furthermore, the pumping device 11 includes a primary impeller 31, in which a secondary impeller 32 is integrated. The primary and secondary impellers 31 and 32 can rotate together about the rotation axis 10. The secondary impeller 32 can be... Figure 7 The design shown has an insert form and can be disposed inside the secondary impeller cavity 312 of the primary impeller 31. The secondary impeller cavity 312 is open toward the pump portion end PSE of the pumping device 11. Alternatively, the primary impeller 31 and the secondary impeller 32 are formed integrally.

[0053] Primary blood flow 1BF flows from primary blood flow inlet 211 to primary impeller 31 outside separator 26, and is further transported by primary impeller 31 to primary blood flow outlet 22 through primary blood flow path 30. Secondary blood flow 2BF flows from secondary blood flow inlet 212 to secondary impeller 32 through separator 26, and is further transported by secondary impeller 32 to primary blood flow path 30 through multiple secondary blood flow paths 321.

[0054] Therefore, the blood flow reaching the pumping device 11 at the end of the pump section, preferably covering 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 location of the secondary blood flow 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 typically laminar, with the highest velocity at the center.

[0055] The primary impeller 31 includes primary impeller blades 313 extending into the primary blood flow path 30, and a primary impeller channel 311 is provided between the primary impeller blades 313. The primary impeller channel 311 has a primary channel inlet 314 at each end of the primary impeller channel 311 facing the pump section end PSE. The secondary impeller 32 includes at least one, and particularly two, secondary blood flow paths 321 in the form of channels, and is therefore also referred to hereinafter as secondary impeller channels 321. The secondary impeller channel 321 has a secondary pitch at a secondary channel inlet 324 located at the upstream end of the secondary impeller channel 321. The secondary pitch is preferably the same as the primary pitch, or may be different to some extent, provided that unintended flow conditions, such as turbulence, can be prevented. At one end of the secondary impeller 32 facing the drive section end DSE, a connecting through opening 315 is provided between the secondary impeller cavity 312 and one of the primary impeller channels 311. The through opening 315 defines a secondary blood flow outlet 213 at one end in the direction of blood flow. The secondary blood flow outlet 213 is further arranged radially outward relative to the axis of rotation 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 delivered through the secondary blood flow inlet 212 and further 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. Thus, the pumped blood flow PBF is formed. The pumped blood flow PBF exits the pumping device 11 at the blood flow outlet 22.

[0056] The primary and secondary impellers 31 and 32 are jointly mounted in the impeller bearing 37. They are connected via the secondary impeller cavity 312 or integrally formed as a single component. The inflow separator 26 includes an impeller bearing ring 27 disposed inside the inflow separator 26. The outer impeller bearing surface 277 of the impeller bearing 37 is disposed inside 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.

[0057] The primary impeller 31 is fixedly connected to a tapered portion 314 leading to the blood outlet 22. The tapered portion 314 guides the pumped blood flow PBF in a radially outward direction relative to the axis of rotation 10. The blood then reaches the blood outlet 22.

[0058] From the narrowing portion 314 toward the pump section end PSE, the drive section 4 is disposed inside the pump housing 2 of the pumping device 11. The drive section 4 includes a stator 40 and a rotor 41. An axial clearance 401 is provided between the stator 40 and the rotor 41. To cool the stator 40 and the rotor 41, the axial clearance 401 is cleaned with blood. For this purpose, an auxiliary blood flow ABF enters the drive section 4 through an auxiliary blood flow inlet 23 provided at the drive section end DSE. Then, the blood is conveyed by the auxiliary impeller 42 through an auxiliary pump clearance 423 provided between the auxiliary impeller 42 and the inner wall of the pump housing 2. The blood continues to flow into the axial clearance 401 from there. The auxiliary blood flow ABF enters the radial clearance 241 from the axial clearance 401. An auxiliary blood flow outlet 24 is provided at the radially outer end of the radial clearance 241. The auxiliary blood flow ABF flows in the axial clearance 401 in a direction opposite to the pumping direction of the primary and secondary impellers 31, 32. The auxiliary blood flow ABF within the drive section 4 also flows in the opposite direction to the general blood flow GBF flowing around the blood pump 1.

[0059] Reference Figure 3 The enlarged view shows that the rotor bearing ring 43 surrounds the auxiliary impeller 42. The auxiliary impeller 42 includes auxiliary impeller blades 421. The auxiliary impeller blades 421 protrude toward the drive portion end DSE of the pumping device 11 in the direction of the rotation axis 10. A radial rotor bearing 47 is disposed at the drive portion end DSE and includes an outer rotor bearing surface 4211 and an inner rotor bearing surface 4311, with an axially extending bearing clearance between them. The outer rotor bearing surface 4311 is disposed on the rotor bearing ring 43. Blood delivered by the auxiliary impeller 42 flows through the bearing clearance and further flows to the axial clearance 401 between the rotor 41 and the stator 40. Blood flows from the axial clearance 401 to the radial clearance 241. The radial clearance 241 extends between the tapering portion 314 of the primary impeller 31 and the stator 40. An auxiliary blood outlet 24 is disposed at the transition between the radial clearance 241 and the periphery of the pumping device 11. The auxiliary blood outlet 24 is configured perpendicular to the rotation axis 10. Here, blood from the auxiliary blood flow ABF merges with the pumped blood flow PBF from pump section 3 and the surrounding general blood flow GBF. As shown, when the auxiliary blood flow outlet 24 is positioned 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 velocities. This enhances the auxiliary blood flow ABF through the axial gap 401.

[0060] The rotation axis 10 extends through the center of the auxiliary impeller 42, and a ridge 422 is provided on the side of the auxiliary impeller 42 opposite to the rotor 41. A bearing pin 44 is provided on the rotation axis 10 in the direction toward the drive section end DSE and adjacent to the ridge 422. The bearing pin 44 is connected to the pump housing 2. The axial bearing surface of the bearing pin 44 toward 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 through the apex of the axial bearing surface of the ridge 422. In this way, the bearing pin 44 interacts with the ridge 422 to form a thrust bearing so as to transmit axial force about the rotation axis between the ridge 422 and the bearing pin 44, wherein the aforementioned parts can rotate relative to each other. Obviously, a smaller contact surface results in less rotational friction.

[0061] The drive section 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 cavity 232, in which the auxiliary impeller 42 is disposed. Therefore, blood flows from the auxiliary blood flow inlet 23 through the auxiliary inlet holes 231 to the auxiliary impeller 42.

[0062] At least one through-hole 25 is provided at the end DSE of the drive portion of the pumping device 11. The through-hole 25 extends from the conduit 5 to the stator 40. Preferably, three through-holes 25 are provided around the axis of rotation 10. One through-hole 25 may be provided between the two auxiliary inlet through-holes 231. In the through-holes 25, at least one supply line 51, 52 and / or 53 may extend to connect to the stator 40. Preferably, as shown, the supply lines 51, 52 and / or 53 extend through the interior of the conduit 5 to the exterior of the patient's body. The supply lines 51, 52 and / or 53 extend from the conduit 5 to the stator 40 without contacting blood.

[0063] Figure 4 A front perspective view of the pump section end PSE of pump section 3 is shown. As shown, the secondary impeller 32 is disposed inside the impeller bearing ring 27. The impeller bearing ring 27 is disposed inside the inflow separator 26. As an alternative to this embodiment, the additional impeller bearing ring 27 can be omitted, such 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 by three supports 28. The secondary blood flow 2BF is shown flowing into the secondary impeller 32 through the secondary blood flow inlet 212, which is disposed 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.

[0064] Figure 5 The pump section end PSE of pump section 3 is shown in perspective, with pump housing 2 shown in a transparent manner. A through opening 315 and a secondary blood flow outlet 213 are visible between the two primary impeller blades 313. As shown, the support 28 is connected by an outer support connecting ring 29. The support connecting ring 29 is disposed within the inner circumferential surface of pump housing 2 at the pump section end PSE. Impeller bearing ring 27 is supported by the support 28. It is conceivable that the support connecting ring 29 and the support 28 are manufactured as a single unit. Preferably, the impeller bearing ring 27 is also part of this component. This component can also be integrally formed with pump housing 2.

[0065] Figure 6 A perspective view of the pump section end PSE of pump section 3 is shown, in which the connection with the pump section is shown in a transparent manner. Figures 3 to 5 The illustrated embodiment features a different pump housing 2, with the inflow separator 26 including at least one cutout 261, preferably three, at its downstream end. The cutouts 261 are positioned between the two supports 28. An impeller bearing ring 27 is part of or fixedly connected to the inflow separator 26, and the cutouts 261 also extend through the impeller bearing ring 27. As the secondary impeller rotates, the cross-section of the secondary impeller passage 321 increases when aligned with the cutouts 261. The secondary impeller 32 extends, at most, within the impeller bearing ring 27 towards the pump section end PSE at one end of the cutout 261. This has the effect that, during operation, the edge of the cutout 261 extends on the impeller inner bearing surface 327 due to the engagement portion of the rotation axis towards the thrust bearing surface 328, removing blood clots at the onset of their formation, or preferably preventing blood clot formation, because the engagement portion of the rotation axis towards the thrust bearing surface 328 is in direct blood contact at the cutout 261. This helps to prevent blood stagnation within the axial thrust bearing. Figure 7 As shown, the inner impeller bearing surface 327 also has an edge 325, which has the function of removing blood clots from the outer impeller bearing surface 277.

[0066] Figure 7The secondary impeller 32 is shown in detail in perspective. Here, the secondary impeller 32 is configured as an insert and is generally cylindrical in shape. It can be made of a different material than the primary impeller 31, for example, ceramic. The insert includes a cylindrical portion 323 disposed inside the secondary impeller cavity 312 of the primary impeller 21. A circumferential protrusion 329 forms an axial stop for the secondary impeller 32 in the secondary impeller cavity 312. An inner impeller bearing surface 327 is disposed 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 away from the blood flow inlet 21. Here, when blood flows through the secondary impeller channels 321, the blood flows from the main axial direction in the axial-radial direction.

[0067] The secondary impeller channel 321 is asymmetrically arranged relative to the rotation axis 10 of the secondary impeller 32. At the end of the secondary impeller 32 pointing towards the blood inlet 21, the rotation axis 10 extends through one of the secondary impeller channels 321. Here, the center of rotation on the rotation axis 10 does not coincide with the solid portion of the secondary impeller 32. This has the advantage of blood pooling at the center of rotation, avoiding the situation where there is no velocity difference with the surrounding blood flow.

[0068] An edge 325 is provided at the transition between the secondary impeller passage 321 and the inner impeller bearing surface 327. As described above, this edge 325 is used to push away blood clot formation 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, which is provided at the 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.

[0069] Figure 8 An enlarged view of the impeller bearing ring 27 is shown. An outer impeller bearing surface 277 is disposed inside 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 the axial end of the impeller bearing ring 27.

[0070] Figure 9 A perspective view of an impeller bearing ring 27 according to another embodiment is shown, which is related to... Figure 8 The illustrated embodiment differs in that it includes a cutout 261, as previously described, located at the downstream end of the impeller bearing ring 27. The number of cutouts 261 is preferably matched to the number of supports 28.

[0071] Figure 10 A cross-sectional perspective view of the drive section end DSE through 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 arrow ABF within the axial gap 401, the blood does not flow directly in the direction of the rotation axis 10, but has a strong circumferential flow component, causing the blood to flow in a spiral along the axial gap 401.

[0072] Figure 11 shows a perspective view of the end of rotor 41 at the drive section end DSE of pumping device 11. The auxiliary impeller blades 421 of auxiliary impeller 42 are clearly identifiable, and they extend straight radially. The auxiliary impeller blades 421 provide the inner rotor bearing surface 4211 of the radial rotor bearing 47 on their outer circumference. Furthermore, each auxiliary impeller blade 421 has a chamfer 4212. This chamfer 4212 facilitates the formation of... Figure 10 The pumping device 11 shown has a tapered drive section end DSE. Furthermore, the auxiliary impeller blade 421 includes a radially extending end face 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, such as... Figure 10 As shown.

[0073] Figure 11A A rotor bearing ring 43 is also shown, disposed around the inner rotor bearing surface 4211 of the auxiliary impeller 42. The outer rotor bearing surface 4311 of the rotor bearing ring 43, together with the inner rotor bearing surface 4211 of the auxiliary impeller 42, forms a rotor bearing 47. 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, the shape, function and arrangement of which are similar to the cutout 261 of the impeller bearing ring 27 described above.

[0074] Figure 12 A perspective view shows one end of the rotor 41 connected to the tapering portion 314 of the primary impeller 31. A third-stage impeller 242 is disposed between the tapering 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 tapering portion 314 to form a shoulder. The axial plane of this shoulder forms a rotatable wall 2411 of the radial clearance 24. The third-stage impeller blades 2412 protrude from the rotatable wall 2411 toward the drive portion end DSE of the pumping device 11. Preferably, the third-stage impeller blades 2412 extend axially along the axis of rotation 10. In particular, the third-stage impeller blades 2412 are straight and extend radially relative to the axis of rotation 10. Alternatively, the third-stage impeller blades 2412 may be omitted.

Claims

1. 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, a downstream end, a distal end and a lateral surface 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) axially extending 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) extending obliquely through the primary impeller (31) starting from a center at a secondary blood flow inlet (212) at the distal end of the primary impeller (31) and ending at the lateral surface of the primary impeller (31) such that a secondary blood flow (2BF) is taken from the center of the coming blood flow and merges into and supports the primary blood flow (1BF) in the primary blood flow passage (30).

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), which rotatably supports the primary impeller (31).

3. The intravascular blood pump of claim 1 or 2, wherein the primary blood flow inlet (211) is separated from the secondary blood flow inlet (212) by a non-rotating inflow separator (26), which forms the outer impeller bearing surface (277) of the impeller bearing (37).

4. The intravascular blood pump of claim 3, wherein the inflow separator (26) comprises an impeller bearing ring (27) as a separating component, which forms the outer impeller bearing surface (277) of the impeller bearing (37).

5. The intravascular blood pump of claim 3 or 4, wherein the inflow separator (26) is supported by at least one and preferably three struts (28) extending across the primary blood flow inlet (211).

6. The intravascular blood pump of 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 any one of claims 3 to 6, wherein the inflow separator (26) comprises at least one cutout (261) at a downstream end of the inflow separator (26).

8. The intravascular blood pump of any one of claims 3 to 7, wherein the inflow separator (26) has at least one cutout (261) in the outer impeller bearing surface (277).

9. Intravascular blood pump according to any of claims 2 to 8, wherein one or more of the at least one secondary blood flow passage (321) is defined by an edge (325) that moves over the outer impeller bearing surface (277) when the primary impeller (31) is rotating, to clean the outer impeller bearing surface (277).

10. Intravascular blood pump according to any of the preceding claims, wherein the impeller bearing (37) is a plain bearing.

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

12. Intravascular blood pump according to any of the preceding claims, wherein the center of the area of the primary blood flow inlet (211) is arranged in a separate secondary blood flow inlet (212).

13. Intravascular blood pump according to any of the preceding claims, wherein a secondary blood flow inlet (212) of the at least one secondary blood flow passage (321) is arranged at the location of the rotation axis (10).

14. Intravascular blood pump according to any of the preceding claims, wherein a secondary channel inlet (324) forming part of the at least one secondary blood flow passage (321) is arranged upstream of a primary channel inlet (314) forming part of a primary impeller channel (311) in the primary blood flow passage (30).

15. Intravascular blood pump according to any of the preceding claims, wherein the primary impeller (31) comprises 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 passage (321) has a secondary pitch that is approximately or exactly the same as the primary pitch.

16. Intravascular blood pump according to any of the preceding claims, wherein exactly one of the at least one secondary blood flow passage (321) has an upstream end arranged at the location of the rotation axis (10).

17. Intravascular blood pump according to any of the preceding claims, wherein at least two of the at least one secondary blood flow passage (321) are arranged asymmetrically with respect to the rotation axis (10).

18. Intravascular blood pump according to any of the preceding claims, wherein two of the at least one secondary blood flow passage (321) are arranged opposite to each other with respect to the rotation axis (10).

19. Intravascular blood pump according to any of the preceding claims, comprising exactly two of the at least one secondary blood flow passage (321).

20. Intravascular blood pump according to any of the preceding claims, wherein the primary impeller (31) comprises an insert in which the at least one secondary blood flow passage (321) is formed.

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