Intravascular blood pump

Abstract

To provide an intravascular blood pump for assisting blood circulation in human beings or arbitrarily and selectively in animals.SOLUTION: An intravascular blood pump (1) includes a pumping device and a catheter (5). The pumping device includes: a driving shaft (12); a rotor (10) located at a distal end of the driving shaft (5); a housing (11) housing the rotor (10); and a distal bearing (14) for rotatably supporting a distal end of the rotor (10). The distal bearing (14) includes a static support member (18) protruding into the distal end of the rotor (10) or by facing the same. The rotor (10) and the housing (11) are expandable. A pin (19) can have enough length to prevent release of the pin (19) from the distal end of the rotor (10) when the rotor (10) and the housing (11) are folded.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present invention relates to an intravascular blood pump for assisting blood circulation in humans or optionally also in animals, in particular a blood pump that can be inserted percutaneously. For example, the blood pump can be designed to be inserted percutaneously into the femoral artery of a patient and guided through the patient's vascular system, for example to assist or replace the pumping action of the heart.

[0002] The present invention is described in the context of an intravascular blood pump having an expandable housing that houses an expandable rotor driven by an extracorporeal motor via a long and highly flexible drive shaft, but the invention is also applicable to other types of intravascular blood pumps where the motor is located inside the patient's body next to the rotor and / or where the housing and rotor are not expandable.

Background Art

[0003] The expandable type of blood pump described above is known, for example, from US 2013 / 0303969 A1, which discloses a catheter pump assembly. The expandable housing is located at the distal end of the catheter. The expandable housing surrounds an expandable rotor driven by a highly flexible drive shaft extending through a first lumen of the catheter. The distal portion of the catheter pump assembly can be placed inside the heart via percutaneous access, for example, using Seldinger technique. The drive shaft includes a central lumen, which allows a guide wire to pass through the drive shaft together with its guide, enabling accurate positioning of the catheter pump assembly inside the heart. The rotor is rotatably supported at the end of the catheter and within a bearing disposed proximally to the rotor. The catheter includes a second lumen for transporting a purge fluid distally to purge at least such a bearing to prevent blood from entering the bearing and clogging it. As used herein, "proximal" and "distal" are as seen by the physician. Thus, when the catheter is placed, proximal refers to what is relatively close to the physician, while distal refers to what is relatively far from the physician.

[0004] Document US 2013 / 0303970 A1 similarly describes an expandable catheter pump assembly with both proximal and distal bearings. The rotor is attached to the drive shaft between the proximal and distal bearings. The distal bearing is held in place by a stationary expandable distal bearing support, which is in slidable contact with the housing when the housing is in its expanded state. The distal bearing support includes a self-sealing septum that allows the guide wire and its guide to pass through. When the guide wire and its guide are removed from the catheter pump assembly, the septum reseals, thus preventing blood from entering the drive shaft. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] One advantage of a distal bearing is that the gap between the rotor blades and the inner surface of the housing can be better controlled to avoid vascular injury even when a rotor with a large diameter is employed. In other arrangements, the distal end of the drive shaft is mounted within a distal bearing that is disposed at the distal end of the housing. However, an intravascular blood pump with a drive shaft supported distally within a bearing from the rotor has the problem that the chordal structures of the heart are drawn into the housing and become entangled around the drive shaft. This can result in damage to the heart structures as well as to the intravascular blood pump, and an increased risk of blood clots forming in the distal bearing.

[0006] To avoid entanglement of the rotating components with tissue, European Patent No. 2047873 A1 describes a polyurethane drive shaft cover and a bearing-hub group that separates the rotating shaft from the blood. However, typically there are still gaps and rotating parts of the hub, so the rotating shaft is exposed around it. This is a problem because the chordal structures of the heart may catch in those gaps or in the distal part of the hub, which can result in injury to the patient and damage to the intravascular blood pump.

[0007] Therefore, there is a need to distally support the rotor inside the housing of the intravascular blood pump without the risk of the chordal structures of the heart becoming entangled within the pump.

Means for Solving the Problem

[0008] According to a first aspect of the present invention, an intravascular blood pump comprises a pumping device and a catheter. The pumping device comprises a drive shaft, a rotor located at the distal end of the drive shaft and housed within a housing, and at least a distal bearing for rotatably supporting the distal end of the rotor. Further, in the blood pump disclosed herein, the distal bearing comprises a static support member that projects into or faces the distal end of the rotor.

[0009] Thus, instead of the drive shaft being supported within the distal bearing, the rotor is attached to the very end of the drive shaft such that the distal end of the rotor is supported by a static support member extending into or facing the rotor, so that the tendon structure is less likely to catch on rotating parts, especially when the rotating cylindrical structure does not extend beyond the leading edge of the rotor blades. This results in a safer intravascular blood pump with a longer lifespan.

[0010] In embodiments where the drive shaft is driven by an external electric motor, the drive shaft preferably extends from the proximal end region of the catheter to the distal end region of the catheter. The drive shaft is typically highly flexible and preferably hollow. The drive shaft preferably consists of or comprises a highly flexible cable preferably formed of fiber layers oriented differently. In particular, the drive shaft cable most preferably consists of a plurality of coaxial winding wires spirally running around a lumen extending axially along the drive shaft, preferably with different winding directions, most preferably with alternating winding directions. For example, the drive shaft cable can comprise two coaxial winding wires with opposite winding directions, and the outer diameter of the drive shaft cable can be 0.4 mm to 2 mm, preferably 0.6 mm to 1.2 mm, and most preferably 0.8 mm to 1.0 mm. The proximal end of the drive shaft cable is preferably attached to the external electric motor. The drive shaft cable serves to transmit torque from the electric motor to the rotor at the distal end of the drive shaft. In some cases, the drive shaft cable may be provided with a rigid and highly rigid shaft at its distal end to provide stability to the rotor, and the rotor is mounted inside the housing on that shaft.

[0011] In the distal end region, in some embodiments, the drive shaft is reinforced by a reinforcing element provided within a lumen extending axially along the drive shaft, such as a metal wire or a carbon wire. In one embodiment, the metal wire is made of 1.4310 stainless steel.

[0012] An intravascular blood pump is preferably designed as an expandable blood pump with a housing having an expandable region. In some embodiments, the housing comprises or consists of a shape memory material, particularly nitinol. The diameter of a percutaneously insertable blood pump is generally limited by the inner diameter of the smallest blood vessel that will be traversed. The intravascular blood pump can be moved through the blood vessel with the housing in a folded state. When it reaches the heart or a larger blood vessel, the housing of the intravascular blood pump can be expanded. This allows a larger blood pump than would otherwise be possible to be percutaneously inserted into the heart. With such a larger blood pump, it may be possible to generate a greater blood flow rate.

[0013] When the blood pump is designed as an expandable pump, the cannula is preferably provided around a portion of the drive shaft proximal to the rotor, and the housing and rotor are configured to be at least partially transferred into the cannula. During such transfer, the expandable region of the housing and the rotor are compressed along a radial direction extending at least transversely to the longitudinal direction, from an expanded state to a compressed state. Preferably, a portion of the rotor, such as rotor blades, or the entire rotor is also expandable to allow a larger rotor to be inserted into the heart, which can improve the flow rate.

[0014] In some embodiments, the static support member protrudes facing the distal end of the rotor. A particularly flexible pump region of the intravascular blood pump can be created as compared to embodiments where the static support member protrudes into the rotor. The high flexibility of the pumping device is particularly advantageous during insertion and removal of the intravascular blood pump. If the static support member does not protrude into the rotor but instead is simply placed facing the distal end of the rotor, it can intentionally disengage from the rotor when the pump region bends during operation of the pumping device passing through the blood vessel. When the pump region reaches its final destination inside the heart, it can straighten, and the static support member can resume its position protruding facing the distal end of the rotor.

[0015] Preferably, the static support member is attached to the distal end of the housing, and the expansion of the housing can provide an axial force onto the distal end of the rotor via the static support member. Preferably, the force is 1.8 N or less. When the static support member protrudes facing the distal end of the rotor, it can limit further expansion of the housing.

[0016] When the housing is compressed, the static support member preferably moves away from the distal end of the rotor. In this state, relative radial movement of the static support member and the rotor is enabled, so that the pump area is more flexible. This can be advantageous during the insertion or retrieval of the intravascular blood pump.

[0017] In certain embodiments, the intravascular blood pump comprises a nose portion at the distal end of the rotor. When the housing is in the expanded state, the nose portion protrudes into the static support member, which preferably holds a correspondingly formed recess. The nose portion is centered on the rotation of the rotor and has the purpose of placing the rotor and the static support member in the correct relative position after the expansion of the housing. The nose portion preferably protrudes 0.1 mm to 2 mm, more preferably 0.2 mm to 1 mm, and most preferably 0.3 mm to 0.5 mm, onto the circumferential surface of the rotor. The depth of the recess in the static support member corresponds to the nose portion and is preferably 0.1 mm to 2 mm, more preferably 0.2 mm to 1 mm, and most preferably 0.3 mm to 0.5 mm.

[0018] In some embodiments where the static support member protrudes into the rotor, the rotor comprises an axial stop for the static support member, such as a recess at its distal end having a bottom or step. The bottom or step defines an axial stop for the proximal end of the static support member at the distal end of the rotor. This is particularly advantageous in the context of an expandable blood pump. In its expanded state, the proximal end of the static support member protruding axially into the rotor can be in contact with the axial stop, thus preventing further expansion of the housing and, thus, limiting the radial clearance width between the outer edge of the rotor blades and the inner surface of the expandable housing. Alternatively, in the expanded state of the expandable blood pump, the proximal end of the static support member and the axial stop can form a gap, which is preferably axially 0.01 mm to 1 mm, more preferably 0.01 mm to 0.1 mm, and most preferably 0.01 mm to 0.05 mm wide.

[0019] The length of the recess at the distal end of the rotor measured axially is, for example, 0.5 mm to 8 mm, preferably 1 mm to 5 mm, and particularly preferably 1.5 mm to 2.5 mm. When the housing is moved into the cannula, the housing preferably extends axially by 0.5 mm to 2.5 mm, more preferably 1 mm to 2 mm, and most preferably approximately 1.7 mm.

[0020] Inside the distal end of the drive shaft, i.e., inside the rotor shaft, the intravascular blood pump may include an optional fluid line arranged to direct purge fluid through the rotor to a distal bearing. In some embodiments, the rotor includes a hollow region as part of the fluid line, and the intravascular blood pump is arranged to direct purge fluid through the hollow region of the rotor to a distal bearing. The purge fluid may be transported to the fluid line via a catheter. When the drive shaft extends through a catheter and is driven by an external electrical motor, the purge fluid may enter the catheter and / or the drive shaft inside the housing of the electrical motor. The purge fluid may flow inside the catheter adjacent to the drive shaft. When the drive shaft is hollow, the purge fluid may flow partially, mainly, or entirely through the drive shaft lumen. From the distal end of the catheter to the rotor, the purge fluid may flow through the drive shaft. In at least the space between the distal end of the catheter and the proximal end of the rotor, the drive shaft may be provided with a cover to prevent the purge fluid from leaking out of the above space.

[0021] Alternatively, the purge fluid may not be directed through the main lumen of the catheter containing the drive shaft, but may be directed through one or more separate secondary lumens. When the electrical motor is placed inside the patient's body together with the pump region, the purge fluid may flow equally through the catheter towards the above fluid line.

[0022] In the distal end region of the catheter, the purge fluid preferably moves into the fluid line inside the rotor shaft. Optionally, the rotor shaft or rotor hub may have a central lumen to accommodate the fluid line. In particular, in the case of a hollow drive shaft cable, the drive shaft cable may extend into the rotor to form both the rotor shaft and the fluid line, or the hollow drive shaft cable may be extended by a hollow tube to form both the rotor shaft and the fluid line. The hollow drive shaft cable may be permeable to the purge fluid.

[0023] In a purged distal bearing, the likelihood of blood entering the bearing clearance is low. As a result, blood clots are prevented. Additionally, a purged bearing can have less friction than alternative distal bearings in the prior art. In particular, the purge fluid can lubricate the bearing and transport frictional heat away from the bearing. This can enable higher rotational speeds, lower power consumption, and an increased lifespan of the blood pump. The purge fluid can be any biocompatible fluid suitable for purging the distal bearing. Examples of suitable medicated solutions include saline with or without heparin, glucose solutions, and / or water.

[0024] In an alternative embodiment, the distal bearing is not purged. Thus, there is no transport of purge fluid to the distal bearing, and the intravascular blood pump may not include a fluid line.

[0025] The distal bearing is preferably arranged such that the purge fluid can exit between a static support member and the distal end of the rotor, where the static support member projects into or faces the distal end of the rotor. Preferably, the distal bearing is arranged such that the purge fluid flows from the distal end of the fluid line to the distal bearing. In particular, the intravascular blood pump can be arranged such that any purge fluid passing through the hollow drive shaft or rotor shaft exits, in whole or in part, through the distal bearing. By applying a suitable pressure, the purge fluid can be forced to pass through the bearing clearance of the distal bearing, which is the clearance surrounded by the adjacent regions of the static support member and the rotor. Preferably, the pressure of the purge fluid is in the range of 300 mmHg (0.4 bar) to 1500 mmHg (2 bar), more preferably in the range of 600 mmHg (0.8 bar) to 1100 mmHg (approximately 1.5 bar). If the distal bearing is purged and the rotor includes a nose portion that projects into the static support member, the nose portion can include at least one opening to allow the purge fluid to enter the bearing clearance between the nose portion and the static support member.

[0026] In some embodiments, the distal end of the static support member is attached to the distal end of the housing. The distal end of the housing may provide a stable support for the static support member that supports the distal end of the rotor.

[0027] The static support member preferably extends distally to proximally and includes a pin that projects toward or preferably into the distal end of the rotor. Thus, the pin can be arranged to form a distal bearing for the rotor. In embodiments where the distal bearing is purged, the pin is preferably arranged such that purge fluid can exit between the pin and the rotor attached to the pin.

[0028] Preferably, the pin has a circular cross-section. However, other cross-sections are equally possible at the distal portion of the pin located outside the rotor. For example, the pin may have an oval cross-section. In some embodiments, the pin may be hollow. Alternatively, the pin can be made of a solid material. Preferably, the pin tapers towards its proximal end. The pin can preferably be elastically bendable such that the rotor remains concentric with the housing during bending of the pump head.

[0029] Preferably, the inner diameter at the distal end of the rotor where the static support member, particularly the pin, projects axially into is in the range of 0.3 mm to 1.5 mm, more preferably in the range of 0.5 mm to 1.2 mm, and most preferably in the range of 0.7 mm to 0.9 mm in width. Preferably, the radial bearing clearance between the outside of the pin and the bearing surface on the opposite side is in the range of 1 μm to 10 μm, more preferably in the range of 2 μm to 8 μm in width.

[0030] In some embodiments, the pins are particularly long, protruding into the rotor and extending proximally through the entire rotor. Preferably, the pins exit the rotor proximally and continue inside the drive shaft, for example, ending inside the proximal bearing. In this case, the ends of the pins can be disposed inside the portion of the drive shaft positioned in the proximal bearing. By employing long pins extending through the entire length of the rotor and into the proximal bearing, a particularly rigid and low-vibration pump can be created. Alternatively, the pins can extend further to a proximal point of the proximal bearing. The pins extending through the rotor can be purged or not purged and can be used in conjunction with a hollow drive shaft or a drive shaft that is not hollow or is only hollow along a portion of its length.

[0031] Preferably, the material of the pins includes at least one of the following materials: a biocompatible material, in particular, one or more of MP35N, 35NLT, nitinol, stainless steel (especially medical-grade stainless steel), and ceramics. The surface of the pins can include a coating, for example, a diamond-like carbon (DLC) coating.

[0032] Preferably, the length of the pins protruding into the distal end of the rotor during the operating state of the intravascular blood pump is 0.5 mm to 8 mm, preferably 1 mm to 5 mm, and particularly preferably 1.5 mm to 2.5 mm. The longer the inner length, the stiffer the rotor, and thus the width of the gap between the outer edge of the rotor blades and the inner surface of the housing can be better controlled. The blades must not contact the inner surface of the housing, and the gap must be large enough to prevent blood damage. A stiffer rotor can also operate with less deflection and less vibration, which improves blood compatibility.

[0033] The pin may have a length sufficient to remain within the distal end of the rotor when the housing and rotor are in a compressed state. The length of the pin that remains inside the distal end of the rotor when the housing and rotor are in a compressed state is preferably greater than 1.5 mm, more preferably greater than 1.7 mm, and most preferably greater than 2 mm. When the housing and rotor are compressed prior to deployment of the blood pump, the housing is extended longitudinally, and the static support member, particularly the pin, extending into the distal end of the housing may possibly entirely disengage from the rotor. Then, when the housing is expanded again, the pin may not return into the rotor, and the pump may not be functional. Thus, such problems can be avoided if the pin is selected with a sufficient length such that it remains inside the rotor even in the compressed state of the housing.

[0034] In embodiments with a pin, the distal bearing surface is the surface of the pin as well as the distal outer bearing surface, which can be provided by the rotor itself or by a distal bearing sleeve within the hub of the rotor. Optionally, the distal outer bearing surface can be provided by the stiffening element described above.

[0035] The distal bearing sleeve may preferably have an inner diameter ranging from 0.3 mm to 1.5 mm, more preferably from 0.5 mm to 1.2 mm, and most preferably from 0.7 mm to 0.9 mm.

[0036] In some embodiments, the intravascular blood pump comprises a highly flexible atraumatic tip to avoid damage to the patient's tissue. The atraumatic tip can be made of a highly flexible medical grade polymer such as Pebax® or polyurethane. Preferably, the highly flexible atraumatic tip is designed as a pigtail or in a J-shape.

[0037] Preferably, the intravascular blood pump comprises a proximal bearing in addition to the distal bearing. The proximal bearing may be located inside the distal end region of the catheter or the proximal end region of the housing. When the proximal bearing is purged, the purge fluid can exit the catheter through the bearing clearance of the proximal bearing. The bearing clearance of the proximal bearing is preferably from 1 μm to 10 μm, more preferably from 2 μm to 8 μm.

[0038] According to a second aspect of the invention, the intravascular blood pump described above is used inside a patient, i.e., it is inserted inside the patient and operated there to assist blood flow. In particular, the purge fluid can be supplied to the intravascular blood pump and exit through the distal bearing via a fluid line.

[0039] Hereinafter, the present invention will be described by way of example with reference to the accompanying drawings. The accompanying drawings are not drawn to scale. In the drawings, each identical or substantially identical component illustrated in the various figures is represented by the same number. For clarity, not all components are labeled in all the figures.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 7

Figure 8A

Figure 8B

Modes for Carrying Out the Invention

[0041] Figure 1 shows the use of an intravascular blood pump 1 to assist the left ventricle 2 of the human heart in this particular example. The intravascular blood pump 1 comprises a catheter 5 and a pumping device, and the pumping device comprises a pump section 4 attached to the distal end region of the catheter 5. The intravascular blood pump 1 can be placed inside the heart using a percutaneous transcatheter technique. For example, the intravascular blood pump 1 can be introduced through the femoral artery. However, alternative vascular accesses are equally possible, such as access through the subclavian artery. After passing through the femoral artery, the catheter 5 can be pushed into the aorta such that the pump section 4 reaches inside the heart through the aortic valve. The positioning of the pump section 4 in Figure 1 serves merely as an example, and different arrangements are possible, such as positioning the pump section 4 inside the right ventricle of the heart.

[0042] The pump section 4 comprises a rotor 10 for flowing blood from a blood flow inlet 6 at the distal end of the pump section 4 to a blood flow outlet 7 located proximal to the blood flow inlet 6. The catheter 5 houses a drive shaft 12 driven by an electric motor 8 preferably placed outside the patient's body. The drive shaft 12 drives a rotor contained inside the pump section 4. The pump section 4 carries, at its distal end, a highly flexible and intact tip 9 in the form of a pigtail or J-shape, which facilitates the placement of the intravascular blood pump 1 by assisting navigation inside the patient's vascular system. Furthermore, the softness of the highly flexible and intact tip 9 enables the pump section 4 to stand independently without damage against the wall of the left ventricle 2.

[0043] Figure 2 shows the intravascular blood pump 1 in more detail. The rotor 10 is located inside the housing 11. In this embodiment, both the rotor 10 and the housing 11 are compressible. In this case, the intravascular blood pump 1 is transported through the patient's vascular system while both the rotor 10 and the housing 11 are in a compressed state. When the pump area 4 reaches its target position, the housing 11 and the rotor 10 are expanded. The highly flexible non-invasive tip 9 is positioned at the distal end of the housing 11. The drive shaft 12 is realized as a highly flexible drive shaft cable. The drive shaft 12 with the rotor 10 disposed at its distal end can be seen protruding from the distal end of the catheter 5. When the rotor 10 inside the housing 11 is rotated by the drive shaft 12, blood is carried into the blood flow inlet 6 at the distal end of the housing 11, through the housing 11, and into the downstream tubing 20 attached to and extending proximally from the housing 11. The blood is then discharged from the downstream tubing 20 through the more proximally located blood flow outlet 7 provided within the downstream tubing 20 and into the aorta. The downstream tubing 20 is made of a highly flexible material so that it can be compressed by the aortic valve when the patient's heart is beating. The downstream tubing 20 typically expands mainly due to the active blood flow generated by the rotating rotor 10. By placing the blood flow inlet 6 inside the left ventricle 2 and the blood flow outlet 7 inside the aorta, the intravascular blood pump 1 can assist the patient's systemic blood circulation. If the intravascular blood pump 1 is configured and placed differently, it can be used, for example, to assist the patient's pulmonary blood circulation instead.

[0044] In this example, a liquid, particularly a purge fluid, is supplied from outside the patient's body through the catheter 5 to the pump region 4. Inside the pump region 4, the liquid can be used to purge one or more bearings to reduce friction and cool the pump region 4, as will be further described in connection with FIGS. 4 and 5. Preferably, the liquid is used to purge at least the distal bearing. In such a case, the pressure of the purge fluid is selected to be higher than the patient's blood pressure to prevent blood from entering the bearing. Preferably, the pressure of the purge fluid is in the range of 300 mmHg (0.4 bar) to 1500 mmHg (2 bar), more preferably in the range of 600 mmHg (0.8 bar) to 1100 mmHg (approximately 1.5 bar).

[0045] The housing 11 is preferably made of a shape memory material such as nitinol and provides a cage around the rotor 10. As seen in FIG. 5, the central portion of the housing 11 holds a sleeve that defines a channel through which blood is pumped by the rotor 10. Proximal and distal to this channel, the housing 11 allows blood to be drawn into the housing 11 and pushed out into the downstream tubing 20 from the housing 11 (as shown in FIG. 2).

[0046] Figures 3A and 3B show the pump section 4, its rotor 10, and its housing 11, in an expanded state and a compressed state, respectively. The cannula 16 is disposed at the distal end of the catheter 5. Initially, prior to the deployment of the intravascular blood pump 1, the pump section 4 is provided in its compressed state inside the cannula 16. The cannula 16 may be attached to the catheter 5 or a peel-away sheath to assist in the insertion of the catheter 5 into the patient's body. When the physician determines that the catheter 5 is properly placed inside the patient's vasculature, the physician pushes the housing 11 out of the cannula 16. When the cannula 16 is removed, the housing 11 expands due to its shape memory properties. At the same time, the rotor 10 expands due to its elasticity. As the housing 11 expands radially away from the drive shaft 12, it contracts longitudinally.

[0047] The rotor 10 is supported within the distal region of the rotor 10 by a distal bearing 14 that includes a static support member 18 having a pin 19. The static support member 18 is attached to the housing 11 at one end and extends into the distal end of the rotor 10 by its pin 19 at the opposite end. Thus, upon expansion of the housing 11, the pin 19 can move axially inside the distal end of the rotor 10. Preferably, the pin 19 is long enough such that when the housing 11 is in its compressed state, the pin 19 remains inside the rotor 10. When the intravascular blood pump 1 is in its expanded state and needs to be removed from the patient, the physician pulls the housing 11 back into the cannula 16, thereby compressing the housing 11 radially and extending it longitudinally. As a result, the distal end of the housing 11 moves away from the rotor 10 together with its pin 19 that extends into the distal ends of the static support member 18 and the rotor 10. The smaller diameter of the housing 11 thus achieved facilitates the removal of the intravascular blood pump 1 from the patient.

[0048] In the prior art distal bearing 14, the drive shaft 12 sometimes extends distally of the rotor 10 and into the bearing. However, this can cause the chordae tendineae of the heart to entangle with the drive shaft 12, potentially leading to clotting and device failure. Therefore, it is advantageous to use a static support member 18 as part of the distal bearing 14 that is not involved in the rotating portion distal to the rotor 10 and distal to the rotor blades.

[0049] Figures 4A and 4B further illustrate in more detail pump section 4 according to a first embodiment, including housing 11 and rotor 10 driven by drive shaft 12. Drive shaft 12 is rotatably supported at both a proximal bearing 13 at the distal end of catheter 5 proximal to rotor 10 (or within the proximal portion of the housing) and a distal bearing 14 located at the distal end of rotor 10. In Figure 4A, drive shaft 12 is hollow at its distal end, or more particularly, the rotor shaft is hollow to form fluid line 15 through which purge fluid can be pumped toward distal bearing 14. If the drive shaft is hollow and extends to the distal end of rotor 10, rotor 10 can be formed directly at the distal end of drive shaft 12 such that the rotor shaft is formed by the drive shaft, whereby in the regions of the proximal and distal bearings, drive shaft 12 can be stiffened, for example, by injection molded plastic material, to provide appropriate outer and inner bearing surface finishes, respectively. Alternatively, the entire end region including the bearing regions of drive shaft 12 can be stiffened to obtain a stiffer structure for the pump section. For example, a rigid hollow tube can be placed over the end of drive shaft 12 and extend distally to form the rotor shaft and bearing regions. Purge fluid can be transported to distal bearing 14 through fluid line 15 within the rotor shaft. In the embodiment shown in Figure 4A, the purge fluid is forced to pass through central fluid line 15, exit drive shaft 12 at its distal end, further pass through the bearing clearance of distal bearing 14, and exit into the bloodstream. Purge of distal bearing 14 by purge fluid results in less friction and thus less wear on the distal bearing, and further prevents blood from entering and clogging the bearing clearance.

[0050] For the intravascular blood pump 1 to be efficient, a large rotor 10 diameter is desirable. However, as the gap between the rotor 10 and the housing 11 decreases, the risk of damage to blood cells or the rotor 10 increases. If only the proximal bearing 13 is used, the system can vibrate, and the gap between the tip of the rotor 10 blades and the inner surface of the housing 11 can undergo large variations. When the highly flexible intact tip 9 contacts the heart wall, the movement of the heart can cause the housing to bend, which can result in the housing contacting the rotor. Contact between the housing and the rotor during use can cause a significant increase in damage to blood cells. As illustrated in FIGS. 4A and 4B, by using both the proximal bearing 13 and the distal bearing 14, the position of the rotor 10 is more stable, and the variation in the size of the gap is lower than in the case of only one bearing. For a given housing 11, this can allow for a larger rotor 10 diameter, thereby enabling a higher flow rate of the intravascular blood pump 1 without the housing contacting the rotor.

[0051] The rotor 10 includes a recess 17 at its distal end. A static support member 18 fixed to the distal end of the housing 11 projects into the recess 17 by its pin 19. The bottom 19 of the recess 17 in FIG. 4A is formed as a step, defining a stop inside the rotor 10 against which the pin 19 of the static support member 18 can rest. In FIG. 4A, the fluid line 15 passes through the bottom of the recess 17 to allow purge fluid to exit from the distal bearing 14 between the pin 19 and the recess 17.

[0052] The embodiment of the intravascular blood pump 1 in FIG. 4B is similar to the embodiment in FIG. 4A. However, importantly, the distal bearing in FIG. 4B is not purged and is instead designed to operate within the blood. Therefore, the drive shaft 12 need not be hollow. Accordingly, there is no fluid line 15 in FIG. 4B. The bottom of the recess 17 does not include an opening for purge fluid to flow through the bearing clearance between the pin 19 and the recess 17. In such an embodiment, less purge fluid may be required. If the proximal bearing is not purged, the intravascular blood pump may not require any purge fluid at all.

[0053] FIG. 4C shows an embodiment similar to FIGS. 4A and 4B. Here, the pin 19 is particularly long and extends proximally through the rotor shaft and into the drive shaft 12. In the embodiment of FIG. 4C, the proximal end of the pin 19 is located inside the portion of the drive shaft 12 that is located inside the proximal bearing 13. In an alternative embodiment, the proximal end of the pin 19 may be located, for example, proximal to the proximal bearing 13 or between the rotor and the proximal bearing.

[0054] By having the pin 19 extend into the proximal bearing 13, greater rigidity of the intravascular blood pump 1 can be achieved. Furthermore, the pin 19 shown in FIG. 4C can help reduce the vibration of the intravascular blood pump 1 during its operation and can reduce unwanted flexure.

[0055] The proximal bearing 13 in FIG. 4C is located inside the housing 11 distally from the location of the proximal bearing 13 in FIGS. 4A and 4B. The distance between the proximal bearing 13 and the rotor 10 is particularly small in the embodiment shown, for example, smaller than the outer diameter of the proximal bearing 13. The short distance can further increase the rigidity of the intravascular blood pump 1.

[0056] In some embodiments, the pin 19 within FIG. 4C can be combined with the hollow drive shaft 12 such that purge fluid can flow through the drive shaft 12, past the pin 19, and out at the distal end of the rotor 10. Alternatively, in some embodiments, purge fluid may not be used. In this case, the long pin 19 of FIG. 4C can be combined with a drive shaft that is not hollow or is hollow only along some portion of its length.

[0057] FIG. 5 shows the pump section 4 according to a second embodiment, again with a rotor 10 driven by a compressible housing 11 and a hollow drive shaft 12. The hollow drive shaft 12 is rotatably supported within a proximal bearing 13 disposed proximal to the rotor 10 at the distal end of the catheter 5.

[0058] In this embodiment, the pin 19 of the static support member 18 that forms part of the distal bearing 14 has a pointed end. If the dimensions of the housing 11 and the pin 19 are such that the pin 19 exits the rotor 10 when the housing 11 is compressed, the pointed end of the pin 19 facilitates reintroduction of the pin 19 into the opening at the distal end 10 of the rotor when the housing 11 is expanded again. Preferably, the pin 19 is long enough such that the pin 19 remains inside the rotor 10 when the housing 11 is in a compressed state. This can avoid a situation where the pin 19 cannot re-enter the rotor 10 when the housing 11 is expanded. In some cases, the proper functioning that requires a bearing clearance to exist over the entire length of the pin 19 is not necessary. Rather, a bearing clearance between the outside of the pin 19 and the opposite bearing surface need only be on the order of 1 μm to 10 μm, more preferably 2 μm to 8 μm in width, at at least one location.

[0059] In this embodiment, rather than providing a bottom or step within the opening at the distal end 10 of the rotor, the static support member 18 may be provided with a shoulder against which the rotor 10 abuts in the expanded state of the housing 11, thereby restricting further expansion of the housing 11 if desired. In some embodiments, the distal bearing 14 may be exclusively a radial bearing.

[0060] Here too, the purge fluid is supplied through the fluid line 15 of the drive shaft 12 towards the distal bearing 14, passes through the pins 19 forming the distal radial bearing for the rotor 10, and can exit the rotor 10 at its distal end. This prevents blood from entering the rotor 10, reduces friction, and cools the distal bearing 14. Alternatively, the distal bearing 14 may not be purged. Thus, the fluid line 15 may not be present.

[0061] Furthermore, in the embodiment shown in FIG. 5, the pins 19 are inside the central duct of the rotor 10 when the housing 11 is expanded. In this case, for example, the drive shaft 12 may terminate at the distal end face of the rotor 10. Alternatively, the distal end of the drive shaft 12 may be located at the level of the bottom of the recess inside the rotor 10, for example as seen in the embodiment of FIG. 4A, so as to form a stop for the pins 19.

[0062] Figures 6A, 6B, 6C, and 6D show a third embodiment of the pump section 4 with a compressible housing 11 and a static support member 18 attached to the housing 11. The rotor 10 includes a nose portion 21 at its distal end. In Figures 6A, 6B, and 6C, the fluid line 15 inside the distal end of the drive shaft 12 leads to an opening within the nose portion 21, through which purge fluid can enter the bearing clearance of the distal bearing 14 between the nose portion 21 and a corresponding recess 22 at the proximal end of the static support member 18. However, in Figure 6D, the distal bearing 14 is not purged. Thus, the embodiment of Figure 6D does not possess the fluid line 15 and the opening within the nose portion 21. The non-purged distal bearing 14 can reduce the amount of purge fluid required to operate the intravascular blood pump 1. In combination with the non-purged proximal bearing 13, the intravascular blood pump 1 may not require any purge fluid at all.

[0063] When the housing 11 is compressed, the nose portion 21 disengages from the recess 22, and thus, the intravascular blood pump 1 becomes more flexible. When the housing 11 is expanded at the target site, the nose portion 21 automatically moves into the recess 22, and the conical or spherical shape of the nose portion 21 helps to guide the nose portion 21 into the recess 22 and center the rotor 10 relative to the static support member 18. Figure 6B shows an enlarged cross-section of the distal bearing 14 with the nose portion 21 and the corresponding recess 22 in the rotor 10. The vertical dashed line in Figure 6B indicates the cross-sectional plane of Figure 6C. The cross-section presented in Figure 6C shows the distal bearing 14 in concentric circles. From the periphery to the center, the concentric circles indicate the recess 22, the distal bearing clearance between the recess 22 and the nose portion 21, the nose portion 21, and the opening of the fluid line 15 into the distal bearing clearance.

[0064] Figure 7 shows the intravascular blood pump 1 together with its catheter 5 and its pump section 4. In this embodiment, the intravascular blood pump 1 includes a proximal bearing 13 inside the distal end of the catheter 5. Purge fluid flows through the catheter 5 at this time and exits the proximal bearing 13 through its bearing clearance. A portion of the purge fluid also flows through the drive shaft 12 and into the rotor 10. The bearing clearance of the proximal bearing is preferably 1 μm to 10 μm, more preferably 2 μm to 8 μm.

[0065] From the drive shaft 12 inside the rotor, the purge fluid flows through the fluid line 15 into the recess 17 of the rotor 10. Arranged inside the recess 17 is the distal bearing sleeve 25 of the rotor 10. The inner surface of the distal bearing sleeve 25 and the outer surface of the pin 19 form the bearing surface of the distal bearing 14. The purge fluid exits the rotor 10 through the bearing clearance between the distal bearing sleeve 25 and the pin 19.

[0066] The distal bearing sleeve 25 preferably has an inner diameter of 0.3 mm to 1.5 mm, more preferably 0.5 mm to 1.2 mm, and most preferably 0.7 mm to 0.9 mm. The outer diameter of the sleeve of the distal bearing 25 is preferably 0.5 mm to 1.7 mm, more preferably 0.7 mm to 1.4 mm, and most preferably 0.9 mm to 1.1 mm. The bearing clearance between the pin 19 and the distal bearing sleeve 25 is preferably 1 μm to 10 μm, more preferably 2 μm to 8 μm.

[0067] FIG. 8A schematically shows a purge fluid path inside an intravascular blood pump. Inside the housing of motor 8, the purge fluid is supplied into catheter 5 and into drive shaft 12. At proximal bearing 13, the purge fluid exits catheter 5 through the bearing clearance to reduce friction and cool proximal bearing 13. A portion of the purge fluid flows through drive shaft 12 into rotor 10 without exiting drive shaft 12 between the distal end of catheter 5 and the proximal end of rotor 10. In some embodiments, drive shaft 12 may comprise a cover such that the purge fluid can flow from catheter 5 to rotor 10 without leaking from drive shaft 12 therebetween. Inside rotor 10, the purge fluid continues to flow through fluid line 15 and then into recess 17 at the distal end 10 of the rotor. In an alternative embodiment, drive shaft 12 may continue to or into recess 17 such that the purge fluid flows directly from drive shaft 12 into recess 17. From there, the purge fluid flows through the bearing clearance of distal bearing 14 between pin 19 and the adjacent surface of rotor 10.

[0068] FIG. 8B shows an embodiment of a blood pump similar to FIG. 8A. In FIG. 8B, proximal bearing 13 is closer to rotor 10 than in FIG. 8A and is separated from rotor 10 only by a small clearance. Through the clearance, the purge fluid may leak as indicated by the arrow.

Claims

1. An intravascular blood pump (1) comprising a pumping device and a catheter (5), wherein the pumping device comprises: a drive shaft (12); a rotor (10) located at the distal end of the drive shaft (12); a housing (11) in which the rotor (10) is received; a distal bearing (14) for rotatably supporting the distal end of the rotor (10); and the distal bearing (14) comprises a static support member (18) protruding into or facing the distal end of the rotor (10), characterized in that it is an intravascular blood pump (1).

2. The intravascular blood pump according to claim 1, wherein the intravascular blood pump (1) is designed as an expandable pump, a cannula (16) is provided around a part of the drive shaft (12) in the vicinity of the rotor (10), and the housing (11) and the rotor (10) are configured to be at least partially transferred into the cannula (12), during such transfer, the expandable area of the housing (11) and the rotor (10) are compressed at least along a radial direction extending transversely to the longitudinal direction from an expanded state to a compressed state, characterized in that it is an intravascular blood pump.

3. The intravascular blood pump according to claim 2, wherein in the expanded state of the housing (11), the static support member (18) protrudes facing the distal end of the rotor (10) with a force of 1.8 N or less, characterized in that it is an intravascular blood pump.

4. The intravascular blood pump according to claim 2 or 3, wherein in the compressed state of the housing (11), the static support member (18) is located away from the rotor (10), characterized in that it is an intravascular blood pump.

5. The intravascular expandable blood pump according to any one of claims 2 to 4, wherein the rotor (10) comprises a nose portion (21) at its distal end, and when the housing (11) is in its expanded state, the static support member (18) protrudes facing the distal end of the rotor (10) with the nose portion (21) protruding into the static support member (18), characterized in that it is an intravascular expandable blood pump.

6. An intravascular blood pump according to claim 1, 2, or 4, wherein the rotor (10) comprises an axial stop for the static support member (18).

7. An intravascular blood pump according to any one of claims 1 to 6, comprising a fluid line (15) inside the distal end of the drive shaft (12) arranged to direct purge fluid to the distal bearing.

8. An intravascular blood pump according to claim 7, wherein the rotor (10) comprises a hollow area as part of the fluid line (15), and the intravascular blood pump (1) is arranged to direct purge fluid through the hollow area of the rotor to the distal bearing (14).

9. An intravascular blood pump according to claim 7 or 8, wherein the distal bearing (14) is arranged such that when purge fluid is directed through the fluid line (15) at a sufficient pressure, at least a portion of the purge fluid exits between the static support member (18) and the distal end of the rotor (10) where the static support member (18) projects into or faces.

10. An intravascular blood pump according to any one of claims 1 to 9, wherein the distal end of the static support member (18) is attached to the distal end of the housing (11).

11. An intravascular blood pump according to any one of claims 1 to 10, wherein the static support member (18) comprises a pin (19) extending from distal to proximal, and the pin (19) projects into the distal end of the rotor (10).

12. An intravascular blood pump according to claim 11, wherein the bearing clearance between the outside of the pin (19) and the bearing surface facing the outside of the pin (19) has a width in the range of 1 μm to 10 μm, preferably 2 μm to 8 μm.

13. An intravascular blood pump according to claim 11 or 12, wherein during the operating state of the intravascular blood pump (1), the length of the pin (19) protruding into the distal end of the rotor (10) is in the range of 0.5 mm to 8 mm, preferably 1 mm to 5 mm, and most preferably 1.5 mm to 2.5 mm. An intravascular blood pump characterized by this.

14. An intravascular blood pump according to any one of claims 11 to 13, accompanied by claim 2, wherein the pin (19) has a length sufficient to remain within the distal end of the rotor (10) when the housing (11) and the rotor (10) are in the compressed state. An intravascular blood pump characterized by this.

15. An intravascular blood pump according to any one of claims 11 to 14, wherein the pin (19) is made of at least one of the following materials: MP35N, 35NLT, Nitinol, stainless steel, and ceramics. An intravascular blood pump characterized by this.

16. An intravascular blood pump according to any one of claims 1, 2, 4, and 6 to 15, wherein the inner diameter at the distal end of the rotor (10) into which the static support member (18) protrudes is in the range of 0.3 mm to 1.5 mm, more preferably 0.5 mm to 1.2 mm, and most preferably 0.7 mm to 0.9 mm. An intravascular blood pump characterized by this.

17. A method of using an intravascular blood pump (1) according to any one of claims 1 to 16 within a patient, such that the blood flow within the patient is assisted by the intravascular blood pump (1) as a result.

Images