How to make a blood pump

Abstract

To provide an intravascular blood pump and a method of manufacturing the intravascular blood pump.SOLUTION: An intravascular blood pump P comprises a pumping device 1 including an impeller 6 and an electric motor for driving the impeller 6. A rotor 7 of the electric motor is rotatable about an axis of rotation and is coupled to the impeller 6 so as to be able to cause rotation of the impeller 6. An outer sleeve 13 forms the casing of the pumping device 1 and stator components are fixed inside the outer sleeve 13 by means of a casting material 18. In a method of making the blood pump P, the stator components including the outer sleeve 13 are placed on a forming base 30, thereby forming a gap 19 between the forming base 30 and the outer sleeve 13 in which the stator components are placed. A casting material 18 is then injected into the gap 19 via the forming base to secure the stator components within the outer sleeve 13.SELECTED DRAWING: Figure 4

Description

Technical Field

[0004] , ,

[0001] The present invention relates to an intravascular blood pump for percutaneous insertion into a patient's blood vessel, particularly an intravascular blood pump to be advanced into a patient's heart, and particularly to a method of manufacturing an intravascular blood pump.

Background Art

[0002] An intravascular blood pump designed to be percutaneously inserted into a patient's blood vessel, such as the femoral or axillary artery or vein, can be advanced into the patient's heart and serve as a left ventricular assist device or a right ventricular assist device. Therefore, the blood pump can also be referred to as an intracardiac blood pump. An intravascular blood pump typically includes a catheter and a pumping device attached to the distal end of the catheter. The catheter may include supply line tubing such as electrical wire and purge tubing. Throughout this disclosure, the term "distal" refers to the direction away from the user and towards the heart, while the term "proximal" refers to the direction towards the user.

[0003] The pumping device may include an electric motor and an impeller coupled to the rotor of the electric motor for rotation of the impeller around a rotational axis. During operation of the blood pump, the impeller transports blood, for example, through a flow cannula, from the blood flow inlet of the blood pump to the blood flow outlet. The pump speed depends on the size of the pumping device. In particular, the efficiency of the electric motor included in the pumping device highly depends on the limited space. However, due to the anatomical limitations for intravascular insertion, it is desirable to reduce the size of the pumping device, particularly its diameter.

[0004] Flow cannulas and catheters are typically flexible enough to follow the anatomical pathways of blood vessels, while pumping devices are rigid. Therefore, to facilitate the navigation of the blood pump into the patient's heart through the patient's blood vessels, it would be desirable to reduce not only the diameter but also the length of the rigid pumping device. Furthermore, relatively long pumping devices can generate relatively strong twists at the junctions between the pumping device and the flow cannula or catheter while advancing the blood pump through curved vessels, which can lead to twisting or breakage.

[0005] In known intravascular blood pumps having a micromotor for driving the impeller of the blood pump, for example, the blood pump disclosed in International Publication No. 98 / 44619(A1), the stator or at least a stator part of the electric motor is encapsulated in a castable material, such as a polymer material, e.g., epoxy. According to the method for fabricating the micromotor disclosed in International Publication No. 98 / 44619(A1), the stator part of the motor is placed on a mandrel, and then the mandrel is inserted into a mold hole. A castable material is poured into the mold hole to encapsulate the stator part and form the housing of the pumping device.

[0006] The injection molding process described above can be carried out in a vacuum atmosphere, which requires a long production cycle, typically taking about 1 to 24 hours, during which each mold is occupied until the injected material is cured. Therefore, a large number of molds must be provided to allow for an increase in the number of parts produced. However, molds are expensive and must be cleaned after each cycle. Furthermore, a release agent such as silicone is usually required, which must be removed from the final product. The resulting electric motor has a relatively thick plastic housing. While this serves the desired role of corrosion protection, it does not further enhance the functionality of the blood pump. On the contrary, the plastic housing increases the diameter of the pumping device and provides thermal insulation, which can lead to undesirable heating of the electric motor during the operation of the blood pump. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, the present invention aims to provide an intravascular blood pump having small external dimensions and, at the same time, an efficient electric motor for increasing pump speed, and a fast and cost-effective method for manufacturing such an intravascular blood pump. [Means for solving the problem]

[0008] This objective is achieved according to the present invention by a method for fabricating an intravascular blood pump and by each intravascular blood pump having the features of an independent claim. Preferred embodiments and further developments of the present invention are specified in the dependent claims.

[0009] According to one aspect of the present invention, a method for fabricating an intravascular blood pump is provided. Specifically, an intravascular blood pump as outlined above is fabricated, comprising an impeller and a pumping device including an electric motor for driving the impeller. The electric motor includes a stator and a rotor, the rotor being rotatable about an axis of rotation and coupled to the impeller so as to cause rotation of the impeller. For fabricating the intravascular blood pump, a molded base is provided, sized and shaped to receive stator components on top of it. Stator components, such as coil windings and optionally other fixed components, are placed on the molded base. Next, an outer sleeve, which may be considered the outermost of the stator components, is placed on the molded base and thereby covering other stator components already placed on the molded base, thereby forming at least a portion of the outer surface of the blood pump and forming a gap between the molded base on which the stator components are placed and the outer sleeve. Next, a polymer material, particularly a pourable molding material such as epoxy resin, is injected into the gap via a molding base, fixing the stator components inside the outer sleeve, i.e., radially inward relative to the outer sleeve.

[0010] The manufacturing method according to the present invention makes it possible to produce an intravascular blood pump having an outer sleeve that forms at least a portion of the outer surface of the pumping device, in which stator components such as coil windings are fixed inside the outer sleeve using a cast material. The stator components are fixed by the cast material; that is, they are fixed in particular to the outer sleeve and to resist relative motion of each other. Stator components such as coil windings, which are completely enclosed by the cast material, are sealed by the cast material, and electrically active components are adequately insulated on both sides from blood and purge fluid to avoid any leakage current or electrolytic corrosion.

[0011] According to this method, the outer sleeve can be considered to form the housing (hereinafter also referred to as the pump casing) of the pumping device by forming at least a portion of the outer surface of the pumping device. The housing, more specifically the outer sleeve, defines the outer surface of the blood pump, more specifically the pumping device, at least within the area in which the blood pump has its maximum outer diameter. Thus, in contrast to well-known intravascular blood pumps, the outer surface or housing is formed by the outer sleeve rather than by a poured material. The poured material is entirely located within the boundary defined by the inner diameter of the outer sleeve. The outer sleeve provides a fluid-sealing barrier to blood or other fluids to protect the stator components from corrosion. The outer sleeve can also function as a soft iron magnet yoke, as described below.

[0012] In other words, the mold for injecting the pourable material is formed by the outer sleeve. That is, the pump casing itself forms the mold, or more specifically, the first casing section of the pump casing is formed by the mold. The first casing section will later be connected to a second casing section to complete the pump casing, and specifically to complete the housing for the motor. Therefore, the manufacturing method according to the present invention does not require an expensive mold that is occupied while the pourable material is curing. The pourable material is injected directly into the interior of the pumping device, more specifically into the gap formed between the outer sleeve and the molding base. Unlike well-known injection molding processes, where typical pourable materials such as epoxy may adhere to undesirable areas on the outer surface of the product and require the removal of excess pourable material, no cleaning of the final product is required because the pourable material is only inside the outer sleeve. This can be particularly significant when it is necessary to prevent delicate structures on the outer surface of the pumping device, such as grooves or similar for sensors, from being exposed to the pourable material. Furthermore, since the product does not need to be removed from the mold hole, this method does not require any release agent, and there is no need to remove any release agent from the surface of the final product. The ability to function without using any release agent also reduces the risk of any undesirable contamination, which could lead to long-term dielectric breakdown of the desired insulation of the poured material. At the same time, other components of the blood pump, in particular fixed components that are not necessarily the electric motor part but are similarly located inside the outer sleeve, such as the ends of the purge tubing, can be easily fixed by the poured material.

[0013] In contrast to well-known molds for injection molding processes, the mold bases used in the method according to the present invention can be easy to manufacture and inexpensive components, and can be produced by injection molding or other techniques such as rapid prototyping, turning, or similar. The mold bases can be formed as disposable components, thus eliminating the need to wait for the poured material to harden before another pumping device can be produced. The mold bases may include plastic materials such as polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), or other plastic materials suitable for withstanding the injection molding process, especially when produced by injection molding. PTFE allows for significantly easier removal of the mold base from the product after hardening.

[0014] Forming the outer surface of the pumping device with an outer sleeve instead of a poured material has the further advantage of reducing the outer diameter of the pumping device, since there is no additional poured material surrounding the pumping device to form the pump casing. For example, the pump casing may have an outer dimension of 18F (French) or less (i.e., an outer diameter of 6 mm or less). Despite the small dimensions, a pumping speed of up to 5.5 liters / minute can be achieved. By reducing the amount of plastic material, heat transfer from the pumping device can be improved thanks to the reduction in plastic insulation. Furthermore, this can reduce the possibility of blood pump failure, particularly at the junctions between the pumping device and the catheter and flow cannula, because the stress peaks at these junctions can be reduced.

[0015] The advantages and effects described above are particularly effective when the outer sleeve contains a magnetoconductive material to form the yoke (back iron) of the electric motor. Therefore, the outer sleeve not only forms a casing without further function, but also serves as a yoke to restrict the magnetic flux of the electric motor. Specifically, the outer sleeve may contain or be made of a metal or a metal alloy, such as a ferrite alloy, e.g., FeCrAl alloy. The outer surface of the sleeve may be coated with the respective oxide. It should be understood that the outer sleeve may contain any suitable biocompatible magnetoconductive material. Metallic materials have the additional advantage of increased heat dissipation and potentially increased structural stability compared to plastic materials.

[0016] In a particularly preferred embodiment, the first stator part to be placed on the molding base may be an inner sleeve, which creates a gap between the inner and outer sleeves for injecting the pourable material. In this case, the inner sleeve forms a cavity for receiving the rotor of an electric motor. In a preferred embodiment, the inner sleeve is made of a ceramic material such as zirconia, or more preferably alumina-toughened zirconia (ATZ). After the inner sleeve is placed on the molding base, other stator parts, such as coil windings, bearings, printed circuit boards, electrical wires, purge tubing, etc., may be placed on the molding base, or more specifically, on the inner sleeve.

[0017] By providing an inner sleeve made of ceramic material, a fluid-sealed enclosure for the cavity in which the rotor is placed can be created. The ceramic material has diffusion resistance to the purge fluid. Therefore, effective corrosion protection of the stator, and in particular electrical stator parts such as coil windings, can be achieved. In this preferred embodiment, since the ceramic sleeve, rather than the inner surface of the poured material, forms the cavity for the rotor, corrosion protection does not depend on the precision of the injection molding process, and the ceramic material of the inner sleeve forms a safe barrier against the purge fluid.

[0018] In addition to the sealing properties of ceramic materials, ceramic inner sleeves offer the advantage of being able to be manufactured with very small manufacturing tolerances. Therefore, for example, by placing the coil windings on the ceramic sleeve before injection molding, the dimensions of the coil windings, particularly the inner diameter and therefore the outer diameter, can be specified and adjusted with great precision. Ceramic sleeves are substantially rigid and easy to handle, which can improve the handling of the coil windings when they are placed on the sleeve. For example, the coil windings can be placed on the molding base together with the inner sleeve. The ceramic material allows for a very small wall thickness of the inner sleeve. This is important to avoid increasing the overall diameter of the pumping device and to maintain a small gap between the stationary coil and the rotating magnet to ensure high motor efficiency and low core temperature.

[0019] The injectable material is preferably fed through the molding base into the gap between the molding base and the outer sleeve. This means that the molding base may be provided as a socket for the injection molding process and may have ports and one or more supply lines configured to supply the injectable material into the outer sleeve, more specifically into the gap between the molding base and the outer sleeve, or preferably into the gap between the inner sleeve and the outer sleeve. Specifically, the injectable material is not supplied to the outside of the outer sleeve.

[0020] The injection of the pourable material may be carried out in a low-pressure atmosphere, particularly in a vacuum, where the gap becomes substantially a vacuum. This can help draw the pourable material into the gap, distribute it throughout the gap, and fix or seal the stator components within the gap and against the outer sleeve.

[0021] To compensate for the shrinkage of the pourable material during the curing process, an excess amount of pourable material may be injected into the gap and guided through it into the drip chamber. In other words, a riser may be provided to prevent bubbles or cavities caused by shrinkage of the pourable material during curing. The drip chamber is preferably located outside the outer sleeve and connected to the gap. This connection will be removed along with the drip chamber after curing is complete. It should be understood that this is the only exception to the injection of pourable material outside the outer sleeve. Nevertheless, in any case, the pourable material will not come into contact with the outer surface of the outer sleeve.

[0022] In one embodiment, the molded base may include pins, preferably metal pins, positioned along the central longitudinal axis of the molded base and protruding from the molded base. The pins may be sized and shaped to receive, for example, a purge pipe extending from a pumping device. The pins may form a portion of the molded base having a minimum diameter. Thus, the metal pins may improve the stability of the molded base. The pins may be coated with, for example, a plastic material used for the rest of the molded base. In other words, the pins may form the central core of the molded base.

[0023] Before the outer sleeve is placed on the molding base, the electrical wires may be connected to at least one of the stator components, preferably a coil winding, for example, by soldering. The established electrical connections will then be fixed, in particular, sealed, by the same casting material. The electrical connections may be placed on the ceramic inner sleeve described above.

[0024] Generally, the molding base in the method of manufacturing a blood pump according to the present invention can be represented as a molding inlay. The molding base can be formed as a mandrel. The mandrel is configured to receive the stator component and the outer sleeve thereon, and can serve to center all the parts disposed thereon. The molding base can have a substantially cylindrical body. More generally, the molding base has a convex body, in particular in contrast to a concave mold cavity.

[0025] The molding base preferably has a shoulder, and a portion of the molding base having a first outer diameter can correspond to a cavity for the rotor of an electric motor, and a portion of the molding base having a second outer diameter smaller than the first outer diameter can substantially correspond to the central hole of the central shaft of the rotor or a bearing, in particular a journal bearing.

[0026] In the above method, the cast molding material is cured after being injected into the gap, and the molding base is preferably separated from the cast molding material supply source before curing the cast molding material. Therefore, the cast molding material and the molding base with the parts of the pumping device can be removed from the injection station and stored for curing. In particular, when the molding base is a disposable part, the mold is not occupied. A plurality of molding bases can be placed on a support after an injection molding process and stored for curing, while the injection process can be continued for further products. Therefore, the method of the present invention is suitable for cost-effective mass production.

[0027] After the injectable material has cured, the molding base is removed. Since the injectable material is placed only within the gap, fixing the stator components and adhering them to the outer sleeve, cleaning is not required. To improve the accuracy of injection molding, the outer sleeve may be sealed to the molding base to prevent the injectable material from leaking out of the outer sleeve, for example by applying adhesive or glue to any possible leakage before injecting the injectable material into the gap. Adhesive may also be applied to parts of the inner part of the outer sleeve to prevent the injectable material from flowing into certain stator compounds, such as bearings.

[0028] The outer sleeve, along with the stator components fixed inside it, forms a first casing section. The cavity inside the outer sleeve, where the molded base is placed during the manufacturing process, will form a cavity for the rotor of the electric motor, specifically for the magnets, which will be inserted into the cavity. Furthermore, a second casing section will be fitted to the first casing section to complete the housing for the motor, and the impeller may be coupled to a shaft that connects to the rotor and extends from the motor housing. Finally, flow cannulas, catheters, and other components that form the blood inlet and outlet may be added to complete the intravascular blood pump.

[0029] In use, purge fluid is directed proximally to distally through the rotor cavity and exits the motor housing where the rotor shaft extends from the motor housing. In addition, the purge fluid can penetrate into the patient's blood through leakage at the junction between the first and second casing sections, if present. This may not be critical, but the purge fluid can further leak through microcracks in the cast material resulting from the shrinkage of the cast material during curing and may reach the coil windings of the stator, which must be avoided. Accordingly, according to a preferred embodiment, at least one seal ring is provided between the outer sleeve and the inner sleeve of the stator component, thereby forming a seal therebetween and thus protecting the coil windings enclosed within the gap between the outer and inner sleeves against the ingress of purge fluid.

[0030] If such a seal ring is provided before injecting and curing the cast material into the gap, the cast material can contact the seal ring, thereby adversely affecting the sealing properties of the seal ring. In this case, it is advantageous to axially provide a second seal ring in line with the first seal ring so that the second seal ring protects the first seal ring against the cast material.

[0031] Since the first seal ring can deteriorate over time due to its contact with the purge fluid, it is further preferred to also arrange the seal ring between the first and second casing sections to seal the first seal ring against the rotor cavity and thus against the purge fluid when the second casing section is attached to the first casing section.

[0032] Alternatively, instead of providing one, two, or even three seal rings as described above, the first casing section may be fitted into the second casing section using a liquid sealing material between the first and second casing sections at the joint with the inner sleeve. The liquid sealing material completely fills all spaces and preferably wets and adheres to all surfaces within such spaces. Once the liquid sealing material dries, the first casing section is sealed to the second casing section at the joint with the inner sleeve, thereby preventing any purging fluid from reaching the poured material surrounding the coil windings. Preferably, the dried liquid sealing material is elastic. For example, an elastomer material that exhibits elastic properties (when cured and dried) may be used as the liquid sealing material to provide a proper sealing function and to compensate for shrinkage of the sealing material during curing.

[0033] The above summary and the following detailed description of preferred embodiments will be better understood when read in conjunction with the accompanying drawings. The drawings are referenced for illustrative purposes of this disclosure. However, the scope of this disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram showing an intravascular blood pump inserted into a patient's heart. [Figure 2] This figure shows a cross-sectional view through an intravascular blood pump according to the first embodiment. [Figure 3a] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 3b] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 3c] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 3d]This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 3e] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 3f] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a first embodiment. [Figure 4] This figure shows a cross-sectional view through a molding base used in a method for manufacturing a first casing section for an intravascular blood pump according to a first embodiment, with the stator components positioned on top. [Figure 5a] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 5b] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 5c] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 5d] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 5e] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 5f] This figure schematically illustrates the steps of a method for fabricating a first casing section for an intravascular blood pump according to a second embodiment. [Figure 6] This figure shows a cross-sectional view through a molding base used in a method for manufacturing a first casing section for an intravascular blood pump according to a second embodiment, with the stator components positioned on top. [Figure 7]This figure shows a cross-sectional view through an intravascular blood pump according to a second embodiment, which includes the first casing section shown in Figure 6. [Modes for carrying out the invention]

[0035] Figure 1 shows an intravascular blood pump P inserted into a patient's heart H. More specifically, the blood pump P comprises a pumping device 1 attached to a catheter 5. The pumping device 1 is inserted into the left ventricle LV of the patient's heart H using the catheter 5 and pumps blood from the left ventricle LV into the aorta AO. The illustrated application is merely illustrative, and the blood pump P of the present invention is not limited to this application. For example, the reverse application for the right ventricle RV can be envisioned. The blood pump P is inserted percutaneously, for example, via a femoral or axillary access and advanced into the heart H through the aorta AO. The blood pump P is positioned such that the blood flow outlet 2 is located outside the patient's heart H in the aorta AO, while the blood flow inlet 3, which is in fluid communication with a flow cannula 4, is located inside the left ventricle LV. An impeller is provided within the pumping device 1 to generate blood flow from the blood inlet 3 to the blood outlet 2, and the rotation of the impeller is generated by an electric motor located within the pumping device 1, as will be described in more detail below.

[0036] Figure 2 shows a cross-sectional view of the pumping device 1 according to the first embodiment, along a central longitudinal axis L that coincides with the rotation axes of the rotor 7 and impeller 6. More specifically, the rotor 7 and impeller 6 are arranged on a common shaft 8 extending along the rotation axis. The rotor 7 of the electric motor is formed as a permanent magnet and is located inside the cavity 22 of the pump casing. To produce the rotation of the rotor 7, coil windings 9, which are part of the stator of the electric motor, surround the rotor 7 and are controllable to produce the rotation of the rotor 7. The impeller 6 is coupled to the rotor 7 via the shaft 8, so that the rotation of the rotor 7 produces the rotation of the impeller 6, which in turn draws blood into the blood flow inlet 3 and out through the flow cannula 4 at the blood flow outlet 2, as indicated by the arrows in Figure 2.

[0037] The shaft 8 is rotatably supported by a distal bearing 12 and a proximal bearing 11, both of which can be formed as journal bearings as shown in Figure 2. The bearings 11, 12 and the shaft 8 may be made of ceramic material. However, other types of bearings, such as ball bearings, may also be used to rotatably support the shaft 8. The bearings may be axial bearings, radial bearings, or composite axial and radial bearings. A purge fluid is supplied through a purge tube 15 through the cavity 22 in which the bearings 11, 12 and the rotor 7 are located. The purge tube 15 extends through the catheter 5 and is connected to the proximal bearing 11 in a fluid-sealed manner. Thus, the purge fluid does not come into contact with the electrical components of the pumping device 1, but only flows through the proximal bearing 11, into the cavity 22, and through the distal bearing 12.

[0038] To provide a safe barrier to protect electrical components, particularly the coil windings 9, from corrosion and short circuits caused by the purge fluid, the cavity 22 for the rotor 7 may be formed by an inner sleeve 14 made of ceramic material. The ceramic inner sleeve 14 is mounted to the proximal bearing 11 in a fluid-seal manner and is resistant to the diffusion of the purge fluid. The ceramic inner sleeve 14 is also very clearly defined by its smooth inner surface, so that in another configuration of the blood pump, some blood may be allowed to enter the pump instead of the purge fluid without causing coagulation or blood breakdown. Further corrosion protection is established by a pourable material 18 that secures the stator components of the pumping device 1 and fills the gap 19 between the inner sleeve 14 and the outer sleeve 13. Specifically, the coil windings 9 are sealed within the pourable material 18. The pourable material 18 also provides additional fixation for the electrical connections 16 (i.e., the printed circuit board PCB) with the motor cable 10 and the purge tubing 15. The pourable molding material 18 may be a resin, preferably a two-component epoxy, and more preferably a polymer material such as a two-component epoxy having thermally conductive and electrically insulating fillers.

[0039] The outer sleeve 13 defines the outer surface and external dimensions of the portion of the pumping device 1. Thus, the outer sleeve 13, which surrounds the aforementioned components, in particular the stator components fixed by the poured material 18, defines the first section of the casing of the pumping device 1. It should be understood that the outer sleeve 13 also forms the stator components, which are magnetically active. The outer sleeve 13 is made of a biocompatible, magnetoconductive material, such as a suitable metal alloy, and serves as a yoke for the magnetic flux of the electric motor. The metal outer sleeve 13 also allows for good dissipation of heat generated by the operation of the electric motor. The outer surface of the outer sleeve 13 may include a groove 21 for receiving a wire having a sensor 20. A hub 17 is attached to the distal end of the outer sleeve 13 and forms a mounting area for the flow cannula 4. The hub 17 is preferably made of the same material as the outer sleeve 13 and houses the distal bearing 12 and the impeller 6. A blood flow outlet 2 is formed within the hub 17, thereby enabling heat transfer from the distal bearing 12.

[0040] The outer sleeve 13 may have a length of approximately 7 mm to approximately 30 mm, preferably approximately 10 mm to approximately 20 mm, and more preferably approximately 10 mm to approximately 15 mm. The outer sleeve 13 may have external dimensions of 18F (French) or less (outer diameter of 6 mm or less). Despite the small dimensions, a pump speed of up to 5.5 liters / minute can be achieved.

[0041] Next, referring to Figures 3a to 3f, the steps for fabricating the first casing section of the intravascular blood pump as shown in Figure 2 will be described. First, as shown in Figure 3a, a ceramic inner sleeve 14 is provided and can be attached to a ceramic end component 11 including a proximal bearing as described above. Attaching the ceramic inner sleeve 14 to the ceramic end component 11 can be achieved, for example, by adhesive, or using one, preferably two, or more preferably three, consecutive seal rings (not shown). That is, one seal ring may be provided on the cavity side of the main seal ring to protect the main seal ring from contact with the purge fluid during use of the blood pump, whereas another seal ring may be provided on the opposite side of the main seal ring to protect the main seal ring from the poured material that may penetrate through the joint between the ceramic inner sleeve 14 and the ceramic end component 11 during the fabrication process of the first casing section, as will be further described below.

[0042] Next, as shown in Figure 3b, the pre-wound coil winding 9 is placed on the sleeve 14. A molded base 30 is provided, formed as a mandrel sized and shaped to receive the stator components of the pumping device 1 (Figure 3c). As shown in Figure 3d, the coil winding 9 with the ceramic sleeve 14 is placed on the molded base 30. Alternatively, the coil winding 9 may be placed on the inner sleeve 14 after the inner sleeve 14 has been placed on the molded base 30. Alternatively, the inner sleeve 14 (i.e., the steps shown in Figures 3a and 3b) may be omitted, and the coil winding 9 may be placed directly on the molded base 30 without the inner sleeve 14. To protect the proximal bearing, i.e., to prevent the poured material from entering the bearing and contaminating the bearing surface, the proximal bearing may be sealed, as further described in relation to Figure 4. As shown in Figure 3e, the motor cable 10 is electrically connected to the coil winding 9, in particular by soldering. Furthermore, the purge pipe material 15 is attached to the end component 11 (not shown here).

[0043] Next, the outer sleeve 13 is placed on the molding base 30 to form the outer surface of the pumping device 1. Then, a pourable molding material such as epoxy is injected into the outer sleeve 13, more specifically into the gap 19 formed between the inner sleeve 14 and the outer sleeve 13, which contains the coil winding 9, thereby sealing the coil winding 9. To compensate for shrinkage during curing, a riser 19a (see Figure 4) with a molten metal reservoir (not shown) may be provided for the pourable molding material. After the injection molding step, which may be carried out in a vacuum, the molding base 30 with the injected pourable molding material can be stored for curing.

[0044] Meanwhile, additional pumping devices can be produced in the same manner and stored for curing. Expensive molds that occupy the curing process and require long production cycles are not needed. The molding base 30 is formed as an inexpensive, disposable plastic part and can be easily removed from the final product. No release agent is required. The poured molding material does not come into contact with the delicate parts of the pumping device. Therefore, cleaning of delicate surface structures, such as the grooves 21 mentioned above, is not required.

[0045] Figure 4 shows a cross-section through the molding base 30, with all desired stator components, including the outer sleeve 13, positioned on top, before the injection of the pourable material 18. Specifically, a ceramic inner sleeve 14, which connects to the proximal bearing 11 and supports the coil windings 9, is positioned on the molding base 30. However, it should be noted that the inner sleeve 14 may be omitted, and the coil windings 9 may be positioned directly on the molding base 30. The motor cable 10 is connected to the electrical connection 16 of the coil windings 9, i.e., the PCB, and is soldered in particular. A purge tube 15 is fixed to the end component 11 to fluidize into the cavity 22 for the rotor 7 (see Figure 2). The metal outer sleeve 13 covers all components and surrounds the gap 19 into which the pourable material will be injected. The inner surface of the proximal end of the end component 11 and the outer surface of the distal end of the purge tube 15 can be sealed to each other with adhesive 23 to prevent leakage of the pourable molding material 18 into the outer sleeve from the gap 19 during the injection process. As can be seen in Figure 2, the purge tube 15 and motor cable 10 extend through the proximal end of the outer sleeve 13, which will be attached to the distal end of the catheter 5. Therefore, the inner surface of the proximal end of the outer sleeve 13 and the outer surfaces of the purge tube 15 and motor cable 10 can be sealed to each other with adhesive 23 to prevent leakage of the pourable molding material 18 into the environment from the gap 19 during the injection process.

[0046] The molded base 30 is produced as an injection-molded disposable plastic part and has a substantially cylindrical body portion 31 that forms a mandrel. Specifically, the body portion 31 is sized and shaped to receive a ceramic inner sleeve 14 on it, or in other words, to correspond to a cavity 22 for receiving the rotor 7 in the final product. The socket portion 32 includes an injection port 33 and a supply conduit 34 for feeding the pourable material 18 into the gap 19 between the inner sleeve 14 and the outer sleeve 13. At the end of the molded base 30 opposite the socket portion 32, a reduced diameter portion 35 extends from the main body portion 32 to receive the bearing 11. Furthermore, a pin portion 36 extends from the portion 35 to receive the purge pipe material 15 on top. Although shown as a single piece, the pin portion 36 may be formed as a metal pin for improved stability. The molded base 30 may be made of, for example, polytetrafluoroethylene, polyethylene, or polypropylene.

[0047] The pourable material 18 is injected into the injection port 33 as indicated by the arrow. To compensate for shrinkage of the pourable material 18 during curing, an excess amount of pourable material 18 may be injected into the gap 19 and guided through it into a riser 19a and into a casing (not shown). The casing may be attached to the riser 19a on the proximal surface 37 of the outer sleeve 13. After the pourable material 18 has cured and the casing has been removed, the molding base 30 is removed if applicable, and the first casing section is completed. Since the pourable material 18 does not come into contact with the outer surface, cleaning of the outer surface of the outer sleeve 13 is not necessary.

[0048] Referring again to Figure 2, the rotor 7, i.e., the magnet, is mounted in the cavity 22 of the pump casing 1 together with the hub 17 and distal bearing 12, and the impeller 6 is coupled to the rotor 7. The hub 17 constitutes a second casing section, and together with the first casing section, forms the housing for the rotor 7. A liquid seal material 40 is provided between the first and second casing sections, more specifically between the inner sleeve 14 and the hub 17, and dried to prevent the purge fluid from reaching the hardened poured material during use of the blood pump and potentially moving toward the coil windings 9 through microcracks in the poured material. At this time, the hub 17 is positioned vertically with its proximal end upright, the liquid seal material 40 is filled into the inner circumferential groove 17a of the hub 17 so as to partially fill the groove, and the first casing section is positioned on the hub 17 such that the distal end of the inner sleeve 14 reaches into the liquid seal material 40. The liquid seal material is then hardened to form a seal. Preferably, the liquid sealing material 40 is an elastomer material so that the seal has elastic properties. Finally, the cannula 4 and catheter 5 are attached to the pump casing 1. It should be understood that not all of the method steps described above are included in the method of the present invention, or other steps may be performed as necessary, as will be understood by those skilled in the art. Similarly, the order of some of the method steps described above may be changed as necessary.

[0049] Figures 5 to 7 relate to a second embodiment, which differs from the first embodiment only in that the (dried) liquid sealing material 40 is omitted and a number of seal rings 40a to 40c are used instead. Thus, Figures 5a to 5f, which schematically show the steps for fabricating the first casing section for an intravascular blood pump according to the second embodiment, differ from Figures 3a to 3f only in that, in the steps described with respect to Figure 5b, the first polymer seal ring 40a and the second polymer seal ring 40b are provided continuously at the bottom or distal end of the coil winding 9. Thus, as can be seen in Figure 6, which shows a cross-section through the molding base 30 with all stator components positioned on top before the pourable molding material 18 is injected into the gap 19, the two seal rings 40a, 40b form a seal at the bottom of the molding base 30. In this second embodiment, the pourable material is supplied to the cavity 19 through the riser 19a, as indicated by the arrow, after the gap 19 has been evacuated. Therefore, the pourable material reaches the first seal ring 40a but not the second seal ring 40b.

[0050] Next, when the hub 17 is fitted into the first casing section, the third seal ring 40c may be positioned inside the hub 17 so that it contacts the inner sleeve 14, thereby forming a seal between the hub 17 and the first casing section. In this way, the purge fluid flowing through the cavity 22 during use of the blood pump is prevented from reaching the second seal ring 40b. Therefore, the second seal ring 40b is completely protected from both sides, providing proper sealing functionality over a long period of time.

Claims

1. A method for manufacturing an intravascular blood pump (P), wherein the blood pump comprises a pumping device (1) including an impeller (6) and an electric motor for driving the impeller (6), the electric motor comprising a stator and a rotor (7), the rotor (7) being rotatable around a rotation axis and coupled to the impeller (6) so as to cause the impeller (6) to rotate, and the method is - A step of providing a molded base (30) that is sized and shaped to receive stator components, - The step of placing the stator components on the molded base (30), - The step of placing an outer sleeve (13) having a length extending in the direction of the rotation axis and a closed circular cross-section with a cross-section perpendicular to the direction of the rotation axis on the molding base (30), thereby forming a gap (19) between the molding base (30) and the outer sleeve (13) on which at least a portion of the outer surface of the blood pump and the stator components are arranged, - The steps of injecting the pourable molding material (18) into the gap (19) via the molding base and fixing the stator components inside the outer sleeve (13), A method characterized by including the following.

2. A method according to claim 1, characterized in that the outer sleeve (13) includes a magnetically conductive material for forming the yoke of the electric motor.

3. A method according to claim 2, characterized in that the outer sleeve (13) includes a metal or a metal alloy.

4. A method according to any one of claims 1 to 3, characterized in that the step of injecting the pourable material (18) includes feeding the pourable material (18) into the gap (19) through the molding base (30).

5. A method according to any one of claims 1 to 4, characterized in that the step of injecting the pourable material (18) is carried out in a low-pressure atmosphere such that the gap (19) becomes substantially a vacuum.

6. A method according to any one of claims 1 to 5, characterized in that the step of injecting the pourable material (18) includes sending an excess amount of pourable material into the gap (19) and guiding it through to the riser (19a).

7. A method according to any one of claims 1 to 6, characterized in that the molding base (30) is a disposable part.

8. A method according to claim 7, characterized in that the molding base (30) is provided as an injection-molded part.

9. A method according to any one of claims 1 to 8, characterized in that the molding base (30) contains a polymer.

10. A method according to claim 9, characterized in that the polymer is polyethylene (PE), polypropylene (PP), or polytetrafluoroethylene (PTFE).

11. A method according to any one of claims 1 to 10, The molding base (30) has a longitudinal axis that extends from the cross-section of the molding base (30) perpendicular to the cross-section and toward the center, A method characterized in that the molding base (30) includes a pin (36) that is arranged along the longitudinal axis of the molding base (30) and protrudes from the molding base (30).

12. A method according to claim 11, characterized in that the pin (36) is provided as a metal pin.

13. A method according to any one of claims 1 to 12, characterized in that the pourable molding material (18) includes a polymer material.

14. A method according to claim 13, characterized in that the polymer material is an epoxy resin.

15. A method according to any one of claims 1 to 14, wherein the method further comprises the step of sealing the outer sleeve (13) to the outside before the step of injecting the pourable material (18).

16. A method according to any one of claims 1 to 15, further comprising the step of connecting an electrical wire (10) to at least one of the stator components prior to the step of arranging the outer sleeve (13) on the molding base (30).

17. A method according to any one of claims 1 to 16, wherein the step of arranging the stator components on the molding base (30) includes arranging an inner sleeve (14) on the molding base (30) such that the gap (19) for injecting the pourable material (18) is formed between the inner sleeve (14) and the outer sleeve (13), and the inner sleeve (14) forms a cavity (22) for receiving the rotor (7).

18. A method according to claim 17, comprising the step of providing at least one seal ring (40a, 40b) between the outer sleeve (13) and the inner sleeve (14) to thereby form a seal between them.

19. A method according to claim 18, characterized in that the two seal rings (40a, 40b) are provided in a row in the direction of the rotation axis.

20. The method according to claim 18 or 19, - The step of curing the pourable material to form a first casing section, - A step of mounting a second casing section onto the first casing section, wherein an additional seal ring (40c) is positioned between the first and second casing sections to seal the at least one seal ring (40a, 40b) against the cavity (22), A method characterized by further comprising:

21. The method according to claim 17, - The step of curing the pourable material to form a first casing section, - A step of mounting the first casing section onto the second casing section, wherein the liquid sealing material (40) is positioned between the first casing section and the second casing section at the joint with the inner sleeve (14), - The steps of curing the liquid sealing material (40) and sealing the first casing section to the second casing section at the joint portion with the inner sleeve (14), A method characterized by further comprising:

22. An intravascular blood pump (P) for percutaneous insertion into a patient's blood vessel, comprising a pumping device (1) including an impeller (6) and an electric motor for driving the impeller (6), wherein the electric motor includes a stator and a rotor (7), the rotor (7) being rotatable about a rotation axis and coupled to the impeller (6) so as to cause rotation of the impeller (6), and the blood pump (P) further comprising an outer sleeve (13) having a length extending in the direction of the rotation axis and a closed circular cross-section perpendicular to the direction of the rotation axis, forming at least a portion of the outer surface of the pumping device (1), a stator component provided radially inward of the outer sleeve (13), and a pourable material (18) provided radially inward of the outer sleeve (13) for fixing the stator component radially inward of the outer sleeve (13).

23. An intravascular blood pump according to claim 22, characterized in that the outer sleeve (13) includes a magnetically conductive material for forming the yoke of the electric motor.

24. An intravascular blood pump according to claim 23, characterized in that the outer sleeve (13) includes metal or a metal alloy.

25. An intravascular blood pump according to any one of claims 22 to 24, comprising an inner sleeve (14) for forming a cavity (22) in which the rotor (7) is received, wherein the inner sleeve (14) is positioned inside the outer sleeve (13), and a gap (19) is formed between the inner sleeve (14) and the outer sleeve (13) in which the stator components fixed by the poured material (18) are positioned.

26. An intravascular blood pump according to claim 25, characterized in that the inner sleeve (14) is made of a ceramic material.

27. An intravascular blood pump according to claim 25 or 26, characterized by comprising at least one sealing ring (40a, 40b) between the outer sleeve (13) and the inner sleeve (14) that forms a seal between them.

28. An intravascular blood pump according to claim 27, characterized in that the two seal rings (40a, 40b) are provided in a row in the direction of the rotation axis.

29. An intravascular blood pump according to claim 27 or 28, further comprising a further seal ring (40c) arranged to seal the at least one seal ring (40a, 40b) with respect to the cavity (22).

30. An intravascular blood pump according to claim 25 or 26, characterized in that it comprises a dried liquid sealing material (40) positioned at the joint with the inner sleeve (14) to seal the pourable material (18) in the gap (19) to the cavity (22).

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