Intravascular Blood Pump

Abstract

The intravascular blood pump (1) includes a pumping device and a catheter (5). The pumping device includes a drive shaft (12), a rotor (10) located at the distal end of the drive shaft (5), a housing (11) in which the rotor (10) is housed, and a distal bearing (14) for rotatably supporting the distal end of the rotor (10). The distal bearing (14) includes a static support member (18) that protrudes into or faces the distal end of the rotor (10). The rotor (10) and the housing (11) may be expandable, and the pin (19) may have a length sufficient to prevent disengagement of the pin (19) from the distal end of the rotor (10) when the rotor (10) and the housing (11) are in a collapsed state.

Description

[Technical field]

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

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

[0003] A blood pump of the expandable type mentioned 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 that is driven by a highly flexible drive shaft that extends through a first lumen of the catheter. The distal part of the catheter pump assembly can be placed inside the heart via percutaneous access, for example using the Seldinger technique. The drive shaft includes a central lumen, which allows a guide wire to pass through the drive shaft together with its guide, allowing a precise positioning of the catheter pump assembly inside the heart. The rotor is rotatably supported at the end of the catheter and in a bearing that is arranged proximal to the rotor. The catheter comprises a second lumen for conveying a purge fluid in a distal direction to purge at least such bearing, in order to prevent blood from entering and clogging the bearing. In this specification, "proximal" and "distal" are as seen relative to the physician. Thus, when placing a catheter, proximal refers to something that is relatively closer to the physician, while distal refers to something that is relatively farther away from the physician.

[0004] Document US 2013 / 0303970 A1 similarly describes an expandable catheter pump assembly with proximal and distal bearings. A 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 that 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 passage of a guidewire and its guide. When the guidewire and its guide are removed from the catheter pump assembly, the septum reseals, thus preventing blood from entering the drive shaft.

[0005] One advantage of the distal bearing is that the clearance between the rotor blades and the inner surface of the housing can be better controlled to avoid vascular damage even when rotors with large diameters are employed. In other arrangements, the distal end of the drive shaft is mounted in a distal bearing located at the distal end of the housing. However, intravascular blood pumps with a drive shaft supported in a distal bearing distal to the rotor have the problem that the tendon structures of the heart are pulled into the housing and entangled around the drive shaft. This can result in the destruction of the cardiac structures as well as damage to the intravascular blood pump and an increased risk of blood clots forming in the distal bearing.

[0006] To avoid entanglement of the rotating parts with tissue, EP 2047873 A1 describes a polyurethane drive shaft cover and bearing-hub assembly that keeps the rotating shaft away from the blood. However, a gap and the rotating part of the hub usually remain, exposing the rotating shaft to its surroundings. This is problematic because tendon structures of the heart may become lodged in the gap or in the distal part of the hub, which may result in injury to the patient and damage to the intravascular blood pump.

[0007] Thus, there is a need to support the rotor distally inside the housing of an intravascular blood pump without the risk of the cardiac tendon structures becoming entangled within the pump. Summary of the Invention [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 a distal end of the drive shaft and housed in 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 against the distal end of the rotor.

[0009] Thus, rather than the drive shaft being supported in a distal bearing, the rotor is instead attached to the very end of the drive shaft such that the distal end of the rotor is supported by a static support member that extends into or against the rotor. In this manner, the tendon structure is less likely to catch on the rotating parts, especially if 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 the embodiment in which the drive shaft is driven by an extracorporeal electric motor, the drive shaft preferably extends from a proximal end region of the catheter to a 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 differently oriented fiber layers. In particular, the drive shaft cable is most preferably composed of a plurality of coaxial windings, preferably with different winding directions, particularly preferably with alternating winding directions, running helically around a lumen extending axially along the drive shaft. For example, the drive shaft cable can comprise two coaxial windings 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, particularly preferably 0.8 mm to 1.0 mm. The proximal end of the drive shaft cable is preferably attached to the extracorporeal electric motor. The drive shaft cable serves to transmit torque from the electric motor to a rotor at the distal end of the drive shaft. In some cases, the drive shaft cable may have a stiff, rigid shaft at its distal end to provide stability to the rotor, on which the rotor is mounted inside the housing.

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

[0012] The intravascular blood pump is preferably designed as an expandable blood pump with a housing having an expandable section. In some embodiments, the housing comprises or consists of a shape memory material, in particular Nitinol. The diameter of a percutaneously insertable blood pump is generally limited by the inner diameter of the smallest blood vessel to be traversed. The intravascular blood pump can be moved through the vessel with the housing in a collapsed state. Upon reaching the heart or a larger vessel, the housing of the intravascular blood pump can be expanded. This allows for a larger blood pump to be inserted percutaneously into the heart than would otherwise be possible. With such a larger blood pump, it may be possible to generate a larger blood flow rate.

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

[0014] In some embodiments, the static support member protrudes facing the distal end of the rotor. Compared to embodiments in which the static support member protrudes into the rotor, a particularly flexible pump section of the intravascular blood pump can be created. 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 may be intentionally dislodged from the rotor when the pump section bends during operation of the pumping device through a blood vessel. When the pump section reaches its final destination inside the heart, it may straighten out and the static support member may resume the position where it protrudes facing the distal end of the rotor.

[0015] Preferably, a static support member is attached to the distal end of the housing, and 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 less than or equal to 1.8 N. When the static support member protrudes against 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, the pump section is more flexible since relative radial movement of the static support member and the rotor is permitted. This can be advantageous during insertion or retrieval of the intravascular blood pump.

[0017] In a particular embodiment, the intravascular blood pump comprises a nose at the distal end of the rotor. When the housing is in the expanded state, the nose projects into the static support member, which preferably possesses a correspondingly formed recess. The nose has the purpose of centering the rotation of the rotor and of placing the rotor and the static support member in the correct relative position after expansion of the housing. The nose projects above the peripheral surface of the rotor by 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. The depth of the recess in the static support member corresponds to the nose 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 base or step. The base 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 gap 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 0.01 mm to 1 mm wide in the axial direction, more preferably 0.01 mm to 0.1, 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, particularly preferably 1.5 mm to 2.5 mm. When the housing is moved into the cannula, it preferably extends axially by 0.5 mm to 2.5 mm, more preferably 1 mm to 2 mm, 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 the purge fluid through the rotor to the distal bearing. In some embodiments, the rotor includes a hollow section as part of the fluid line, and the intravascular blood pump is arranged to direct the purge fluid through the hollow section of the rotor to the distal bearing. The purge fluid may be transported to the fluid line via a catheter. If the drive shaft extends through the catheter and is driven by an extracorporeal electric motor, the purge fluid may enter the catheter and / or the drive shaft inside the housing of the electric motor. The purge fluid may flow inside the catheter adjacent to the drive shaft. If 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. At least in the space between the distal end of the catheter and the proximal end of the rotor, the drive shaft may include a cover to prevent the purge fluid from leaking out of said space.

[0021] Alternatively, the purge fluid may not be directed through the main lumen of the catheter, including the drive shaft, but through one or more separate secondary lumens. If the electric motor is located inside the patient's body along with the pump section, the purge fluid may equally flow through the catheter toward the fluid lines.

[0022] At the distal end region of the catheter, the purge fluid preferably travels into the fluid lines inside the rotor shaft. In some cases, the rotor shaft or rotor hub may have a central lumen to accommodate the fluid lines. 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 lines, or the hollow drive shaft cable may be extended by a hollow tube to form both the rotor shaft and the fluid lines. The hollow drive shaft cable may be permeable to the purge fluid.

[0023] In a purged distal bearing, blood is less likely to enter the bearing gap. As a result, blood clots are prevented. In addition, the purged bearing may have less friction than alternative distal bearings in the prior art. In particular, the purging fluid can lubricate the bearing and transport frictional heat away from the bearing. This may allow for higher rotational speeds, lower power consumption, and increased lifespan of the blood pump. The purging fluid may be any biocompatible fluid suitable for purging the distal bearing. Examples of suitable pharmaceutical fluids include saline with or without heparin, glucose solution, and / or water.

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

[0025] The distal bearing is preferably arranged so that the purge fluid can exit between the static support member and the distal end of the rotor into or against which the static support member projects. Preferably, the distal bearing is arranged so that the purge fluid flows from the distal end of the fluid line to the distal bearing. In particular, the intravascular blood pump may be arranged so 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 may be forced through a bearing gap of the distal bearing, the bearing gap being a gap surrounded by the static support member and adjacent areas of 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). Where the distal bearing is purged and the rotor includes a nose portion that protrudes into the static support member, the nose portion may include at least one opening to allow purge fluid to enter the bearing gap 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 can provide a stable support for the static support member that supports the distal end of the rotor.

[0027] The static support preferably includes a pin extending from distal to proximal and projecting against, or preferably into, the distal end of the rotor. The pin may thus be positioned to form a distal bearing for the rotor. In embodiments in which the distal bearing is purged, the pin is preferably positioned to allow purge fluid to exit between the pin and the rotor attached to the pin.

[0028] Preferably, the pin possesses 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 may be made of a solid material. Preferably, the pin is tapered towards its proximal end. The pin may preferably be elastically bendable so that the rotor remains concentric relative to the housing during flexion of the pump head.

[0029] Preferably the inner diameter at the distal end of the rotor where the static support members, particularly the pins, protrude axially inwards is 0.3mm to 1.5mm wide, more preferably 0.5mm to 1.2mm wide and most preferably 0.7mm to 0.9mm wide. Preferably the radial bearing gap between the outside of the pin and its opposite bearing surface is 1μm to 10μm wide, more preferably 2μm to 8μm wide.

[0030] In some embodiments, the pin is particularly long, protruding into the rotor and extending proximally through the entire rotor. Preferably, the pin exits the rotor proximally and continues inside the drive shaft, for example terminating inside the proximal bearing. In this case, the end of the pin may be located inside the portion of the drive shaft that is located in the proximal bearing. By employing a long pin that extends through the entire length of the rotor and into the proximal bearing, a particularly stiff, low vibration pump may be created. Alternatively, the pin may extend further to a point proximal to the proximal bearing. Pins that extend through the rotor may or may not be purged and may be used in conjunction with hollow drive shafts as well as drive shafts that are solid or hollow along only a portion of their length.

[0031] Preferably, the material of the pin comprises at least one of the following materials: a biocompatible material, in particular one or more of MP35N, 35NLT, Nitinol, stainless steel (in particular medical grade stainless steel), and ceramics. The surface of the pin may comprise a coating, for example a diamond-like carbon (DLC) coating.

[0032] Preferably, the length of the pins that protrude 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, particularly preferably 1.5 mm to 2.5 mm. The longer the protruding length, the stiffer the rotor is, and therefore 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 be operated with lower deflections and less vibration, which improves blood compatibility.

[0033] The pin may have a sufficient length 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 longitudinally extended and the static support members, particularly the pins, that extend into the distal end of the housing may possibly slip out entirely from the rotor. Then, when the housing is expanded again, the pins may not return into the rotor and the pump may not be functional. Thus, such problems may be avoided if the pins are selected with a sufficient length such that they remain inside the rotor even in the compressed state of the housing.

[0034] In embodiments involving pins, the distal bearing surface is the surface of the pin as well as the distal outer bearing surface, which may be provided by the rotor itself or by a distal bearing sleeve in the hub of the rotor. In some cases, the distal outer bearing surface may be provided by the stiffening element mentioned 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 may 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 gap of the proximal bearing. The bearing gap of the proximal bearing is preferably 1 μm to 10 μm, more preferably 2 μm to 8 μm.

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

[0039] The invention will now be described, by way of example only, with reference to the accompanying drawings, which are not drawn to scale, in which each identical or nearly identical component illustrated in the various figures is represented by the same numeral, and for clarity, not every component is numbered in every figure. [Brief description of the drawings]

[0040] [Figure 1] FIG. 1 is a schematic diagram of an intravascular blood pump positioned within the left ventricle of the heart. [Diagram 2] FIG. 1 is a schematic diagram of an intravascular blood pump. [Figure 3A] 1A-1C are schematic diagrams of an intravascular blood pump in expanded and compressed states. [Figure 3B] 1A-1C are schematic diagrams of an intravascular blood pump in expanded and compressed states. [Figure 4A] 1 is a schematic diagram of an intravascular blood pump according to a first embodiment with a static support member extending into a distal end of the rotor. FIG. [Figure 4B] 1 is a schematic diagram of an intravascular blood pump according to a first embodiment with a static support member extending into a distal end of the rotor. FIG. [Figure 4C]1 is a schematic diagram of an intravascular blood pump according to a first embodiment with a static support member extending into a distal end of the rotor. FIG. [Diagram 5] 1 is a schematic diagram of an intravascular blood pump according to a second embodiment with a static support member extending into the distal end of the rotor. [Figure 6A] 13 is a schematic diagram of an intravascular blood pump with a rotor having a nose at its distal end according to a third embodiment. [Figure 6B] 13 is a schematic diagram of an intravascular blood pump with a rotor having a nose at its distal end according to a third embodiment. [Figure 6C] 13 is a schematic diagram of an intravascular blood pump with a rotor having a nose at its distal end according to a third embodiment. [Figure 6D] 13 is a schematic diagram of an intravascular blood pump with a rotor having a nose at its distal end according to a third embodiment. [Figure 7] FIG. 1 is a schematic diagram of an intravascular blood pump with proximal and distal bearings. [Figure 8A] FIG. 1 is a schematic diagram of the path of purge fluid in an intravascular blood pump. [Figure 8B] FIG. 1 is a schematic diagram of the path of purge fluid in an intravascular blood pump. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] FIG. 1 illustrates the use of an intravascular blood pump 1 to assist the left ventricle 2 of a human heart, in this particular example. The intravascular blood pump 1 comprises a catheter 5 and a pumping device, the pumping device comprising a pump section 4 attached to a distal end region of the catheter 5. The intravascular blood pump 1 may be placed inside the heart using a percutaneous transluminal technique. For example, the intravascular blood pump 1 may be introduced through the femoral artery. However, alternative vascular accesses are possible as well, such as access through the subclavian artery. After passing through the femoral artery, the catheter 5 may be pushed into the aorta such that the pump section 4 passes through the aortic valve and reaches into the heart. The positioning of the pump section 4 in FIG. 1 merely serves 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 includes a rotor 10 for driving blood from a blood flow inlet 6 at a 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 located outside the patient's body. The drive shaft 12 drives a rotor contained inside the pump section 4. At its distal end, the pump section 4 possesses a flexible atraumatic tip 9 having a pigtail or J-shaped configuration, which facilitates placement of the intravascular blood pump 1 by aiding in navigation inside the patient's vasculature. Furthermore, the softness of the flexible atraumatic tip 9 allows the pump section 4 to stand uninjured against the wall of the left ventricle 2.

[0043] FIG. 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 section 4 is at its target location, the housing 11 and the rotor 10 are expanded. The flexible atraumatic tip 9 is located at the distal end of the housing 11. The drive shaft 12 is realized as a flexible drive shaft cable. The drive shaft 12 with the rotor 10 located at its distal end is 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 transported into the blood inlet 6 at the distal end of the housing 11 and through the housing 11 into the downstream tubing 20 attached to the housing 11 and extending proximally. The blood is then discharged from the downstream tubing 20 through a more proximally located blood flow outlet 7 provided in 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 primarily due to the active blood flow generated by the spinning 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 support the patient's systemic blood circulation. If the intravascular blood pump 1 is configured and positioned differently, it can be used, for example, to support the patient's pulmonary blood circulation instead.

[0044] In this example, a liquid, in particular a purge fluid, is supplied from outside the patient's body through a catheter 5 to the pump section 4. Inside the pump section 4, the liquid may be used to purge one or more bearings to reduce friction and cool the pump section 4, as will be further explained in relation to 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 bearings. 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] Housing 11 is preferably fabricated from a shape memory material, such as Nitinol, and provides a cage around rotor 10. As seen in Figure 5, a central portion of housing 11 holds a sleeve that defines a channel through which blood is pumped by rotor 10. Proximal and distal to this channel, housing 11 allows blood to be drawn into housing 11 and pushed out of housing 11 into downstream tubing 20 (as shown in Figure 2).

[0046] 3A and 3B show the pump section 4, its rotor 10, and its housing 11 in an expanded and compressed state, respectively. A cannula 16 is disposed at the distal end of the catheter 5. Initially, prior to 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 a cannula 16 attached to the catheter 5 or a peel-away sheath to aid 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 in the distal region of the rotor 10 by a distal bearing 14 comprising a static support member 18 having a pin 19 attached to the housing 11 at one end and extending into the distal end of the rotor 10 at its opposite end by its pin 19 so that upon expansion of the housing 11, the pin 19 can move axially inside the rotor's distal end 10. Preferably, the pin 19 is long enough to remain inside the rotor 10 when the housing 11 is in its compressed state. When the intravascular blood pump 1 is in its expanded state and needs to be removed from the heart, the physician pulls the housing 11 back into the cannula 16, thereby radially compressing the housing 11 and lengthening it longitudinally, so that the distal end of the housing 11 moves away from the rotor 10 together with the static support member 18 and its pin 19 extending into the distal end of the rotor 10. The smaller diameter of the housing 11 thus achieved facilitates removal of the intravascular blood pump 1 from the patient.

[0048] In prior art distal bearings 14, the drive shaft 12 sometimes extends into the bearing distal to the rotor 10. However, this can cause the cardiac chordae to become entangled with the drive shaft 12, potentially leading to clotting and device failure. Therefore, the use of a static support member 18 as part of the distal bearing 14 that does not involve a rotating portion distal to the rotor 10 and distal to the rotor blades is advantageous.

[0049] 4A and 4B illustrate in more detail the pump section 4 according to the first embodiment, including the housing 11 and the rotor 10 driven by the drive shaft 12. The drive shaft 12 is rotatably supported both in a proximal bearing 13 at the distal end of the catheter 5 proximal to the rotor 10 (or in the proximal part of the housing) and in a distal bearing 14 located at the distal end of the rotor 10. In FIG. 4A, the drive shaft 12 is hollow at its distal end, or more specifically, the rotor shaft is hollow to form a fluid line 15 through which a purge fluid can be pumped towards the distal bearing 14. If the drive shaft is hollow and extends to the distal end of the rotor 10, the rotor 10 can be formed directly at the distal end of the drive shaft 12 such that the rotor shaft is formed by the drive shaft, so that in the region of the proximal and distal bearings the drive shaft 12 can be stiffened, for example by injection molded plastic material, and provided with suitable outer and inner bearing surface finishes, respectively. Alternatively, the entire end region of the drive shaft 12, including the bearing section, can be stiffened to obtain a stiffer structure of the pump section. For example, a stiff hollow tube can be placed over the end of the drive shaft 12 and extended distally to form the rotor shaft and bearing section. The purge fluid can be transported through a fluid line 15 in the rotor shaft to the distal bearing 14. In the embodiment shown in FIG. 4A, the purge fluid is forced through the central fluid line 15 to exit the drive shaft 12 at its distal end, further through the bearing gap of the distal bearing 14 and into the bloodstream. Purging the distal bearing 14 with the purge fluid results in less friction and therefore less wear on the distal bearing, and also prevents blood from entering and clogging the bearing gap.

[0050] For an intravascular blood pump 1 to be efficient, a large rotor 10 diameter is desirable. However, as the clearance between the rotor 10 and the housing 11 becomes smaller, the risk of blood cells or the rotor 10 being damaged increases. If only the proximal bearing 13 is used, the system may vibrate and the clearance between the tips of the rotor 10 blades and the inner surface of the housing 11 may undergo large changes. When the flexible intact tip 9 contacts the heart wall, the movement of the heart may cause bending of the housing, which may result in the housing contacting the rotor. Contact of the housing and the rotor during use may cause a significant increase in damage to blood cells. As illustrated in Figures 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 clearance is lower than with only one bearing. For a given housing 11, this may allow the rotor 10 diameter to be larger, which allows a higher flow rate of the intravascular blood pump 1 without the housing contacting the rotor.

[0051] At its distal end, the rotor 10 comprises a recess 17. A static support member 18, which is fixed relative 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 and defines an inner stop of 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 the purge fluid to exit 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. Importantly, however, the distal bearing in FIG. 4B is not purged, but instead is designed to operate in blood. Thus, the drive shaft 12 does not need to be hollow. Thus, 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 gap 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 purge fluid at all.

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

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

[0055] The proximal bearing 13 in Fig. 4C is located inside the housing 11, distal from the location of the proximal bearing 13 in Fig. 4A and Fig. 4B. The distance between the proximal bearing 13 and the rotor 10 is particularly small in the embodiment shown, e.g., smaller than the outer diameter of the proximal bearing 13. The short distance may further increase the stiffness of the intravascular blood pump 1.

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

[0057] FIG. 5 shows a 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 which is rotatably supported in a proximal bearing 13 located proximally 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, which 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 for the pin 19 to remain inside the rotor 10 when the housing 11 is in a compressed state. This may avoid a situation where the pin 19 cannot re-enter the rotor 10 when the housing 11 is expanded. In some cases, proper function of the required bearing clearance being present over the entire length of the pin 19 is not necessary. Rather, it is sufficient that the bearing clearance between the outside of the pin 19 and its opposite bearing surface is 1 μm to 10 μm wide, more preferably 2 μm to 8 μm wide, at least in one place.

[0059] In this embodiment, rather than providing a bottom or step in the opening at the rotor's distal end 10, 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 limiting further expansion of the housing 11, if desired. In some embodiments, the distal bearing 14 may be exclusively a radial bearing.

[0060] Again, purging fluid may be fed through fluid line 15 of drive shaft 12 towards distal bearing 14, passing through pins 19 which form the distal radial bearing for rotor 10, and exiting rotor 10 at its distal end. This prevents blood from entering rotor 10, reduces friction, and cools distal bearing 14. Alternatively, distal bearing 14 may not be purged; therefore, fluid line 15 may not be present.

[0061] Moreover, in the embodiment shown in Fig. 5, the pin 19 is 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 inside the rotor 10, for example at the level of the bottom of the recess, as seen in the embodiment of Fig. 4A, so as to form a stop for the pin 19.

[0062] 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 mounted on the housing 11. The rotor 10 comprises a nose 21 at its distal end. In 6A, 6B, and 6C, the fluid line 15 inside the distal end of the drive shaft 12 leads to an opening in the nose 21 through which the purge fluid can enter the bearing gap of the distal bearing 14 between the nose 21 and a corresponding recess 22 at the proximal end of the static support member 18. However, in 6D, the distal bearing 14 is not purged. Thus, the embodiment of 6D does not possess the fluid line 15 and the opening in the nose 21. The non-purged distal bearing 14 may reduce the amount of purge fluid required to operate the intravascular blood pump 1. Combined 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 moves out of 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 with respect to the static support member 18. FIG. 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 FIG. 6B indicates the cross section plane of FIG. 6C. The cross section presented in FIG. 6C displays the distal bearing 14 with concentric circles. From the periphery to the center, the concentric circles indicate the recess 22, the distal bearing gap 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 gap.

[0064] 7 shows the intravascular blood pump 1 with its catheter 5 and its pump section 4. In this embodiment, the intravascular blood pump 1 comprises a proximal bearing 13 inside the distal end of the catheter 5. The purge fluid then flows through the catheter 5 and exits the proximal bearing 13 through the bearing gap. Part of the purge fluid also flows through the drive shaft 12 and into the rotor 10. The bearing gap of the proximal bearing is preferably 1 μm to 10 μm, and more preferably 2 μm to 8 μm.

[0065] From the drive shaft 12 inside the rotor, the purge fluid flows through fluid line 15 and into recess 17 of rotor 10. Disposed inside recess 17 is a distal bearing sleeve 25 of rotor 10. The inner surface of distal bearing sleeve 25 and the outer surface of pin 19 form the bearing surface of distal bearing 14. The purge fluid exits rotor 10 through the bearing gap between distal bearing sleeve 25 and 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 gap 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 shows a schematic of the purge fluid path inside the intravascular blood pump. Inside the housing of the motor 8, the purge fluid is fed into the catheter 5 and into the drive shaft 12. At the proximal bearing 13, the purge fluid exits the catheter 5 through a bearing gap to reduce friction and cool the proximal bearing 13. A portion of the purge fluid does not exit the catheter 5 through the bearing gap but flows through the drive shaft 12 into the rotor 10. In some embodiments, the drive shaft 12 may include a cover so that the purge fluid can flow from the catheter 5 to the rotor 10 without leaking out of the drive shaft 12 between the distal end of the catheter 5 and the proximal end of the rotor 10. Inside the rotor 10, the purge fluid continues to flow through the fluid line 15 and then into the recess 17 at the distal end 10 of the rotor. In an alternative embodiment, the drive shaft 12 may continue up to or into the recess 17 so that the purge fluid flows directly from the drive shaft 12 into the recess 17. From there, the purge fluid flows through the bearing gap of the distal bearing 14 between the pin 19 and the adjacent surface of the rotor 10 .

[0068] Figure 8B shows an embodiment of a blood pump similar to Figure 8A, in which the proximal bearing 13 is closer to the rotor 10 than in Figure 8A and is separated from the rotor 10 only by a small gap through which the purge fluid can leak, as shown by the arrows.

Claims

1. An expandable intravascular blood pump (1) comprising a pumping device and a catheter (5), said pumping device comprising: A drive shaft (12); a rotor (10) located at a distal end of the drive shaft (12); a housing (11) in which the rotor (10) is housed and which has an expandable area; a distal bearing (14) for rotatably supporting a distal end of the rotor (10); Equipped with The distal bearing (14) comprises a static support member (18); An intravascular blood pump (1), characterized in that the static support member (18) is mounted at a distal end of the housing (11) and projects into or against the distal end of the rotor (10).

2. 2. The intravascular blood pump of claim 1, wherein a cannula (16) is provided around a portion of the drive shaft (12) in the vicinity of the rotor (10), and the housing (11) and the rotor (10) are configured to be transported at least partially into the cannula (16), and during such transport, the expandable section of the housing (11) and the rotor (10) are compressed from an expanded state to a compressed state at least along a radial direction extending transversely to a longitudinal direction.

3. 3. An intravascular blood pump according to claim 2, characterized in that in the expanded state of the housing (11), the static support member (18) protrudes against the distal end of the rotor (10) with a force of less than 1.8 N.

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

5. An intravascular blood pump according to any one of claims 2 to 4, characterized in that the rotor (10) has a nose portion (21) at its distal end, and when the housing (11) is in its expanded state, the static support member (18) projects against the distal end of the rotor (10) with the nose portion (21) projecting into the static support member (18).

6. 5. An intravascular blood pump according to claim 1, 2 or 4, characterized in that the rotor (10) is provided with an axial stop for the static support member (18).

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

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

9. 9. An intravascular blood pump according to claim 7 or 8, characterized in that the distal bearing (14) is arranged such that, when purge fluid is induced through the fluid line (15) with 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) into which or against which the static support member (18) projects.

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

11. An intravascular blood pump as claimed in any one of claims 1 to 10, characterized in that the static support member (18) comprises a pin (19) extending from distal to proximal, the pin (19) protruding into the distal end of the rotor (10).

12. 12. An intravascular blood pump according to claim 11, characterized in that the bearing gap 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.

13. An intravascular blood pump according to claim 11 or 12, characterized in that the length of the pin (19) by which it protrudes into the distal end of the rotor (10) during the operating state of the intravascular blood pump (1) is in the range of 0.5 mm to 8 mm.

14. An intravascular blood pump according to any one of claims 11 to 13 accompanied by claim 2, characterized in that 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.

15. An intravascular blood pump according to any one of claims 11 to 14, characterized in that the pins (19) are made of at least one of the following materials: MP35N, 35NLT, Nitinol, stainless steel and ceramics.

16. An intravascular blood pump according to any one of claims 1, 2, 4 and 6 to 15, characterized in that 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.

17. An intravascular blood pump as described in claim 12, characterized in that the width of the bearing gap is within the range of 2 μm to 8 μm.

18. An intravascular blood pump as described in claim 13, characterized in that the length of the pin (19) that protrudes into the distal end of the rotor (10) is within the range of 1 mm to 5 mm.

19. An intravascular blood pump as described in claim 18, characterized in that the length of the pin (19) that protrudes into the distal end of the rotor (10) is within the range of 1.5 mm to 2.5 mm.

20. The intravascular blood pump of claim 16, An intravascular blood pump, characterized in that the inner diameter of the rotor (10) at the distal end is in the range of 0.5 mm to 1.2 mm.

21. The intravascular blood pump of claim 20, An intravascular blood pump, characterized in that the inner diameter of the rotor (10) at the distal end is in the range of 0.7 mm to 0.9 mm.

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