Blood pump

Abstract

A blood pump (1) comprising a pump section (2) and a fluid cannula (3). A proximal portion (14) of the fluid cannula (3) is connected to the pump section (2) such that blood can enter a blood flow inlet (11), and a distal portion (13) of the fluid cannula (3) includes at least one blood flow opening (16) for allowing blood to enter the fluid cannula (3). The distal portion (13) includes an enlarged diameter portion (15), wherein at least most of the blood flow opening (16) is provided in the enlarged diameter portion (15). The blood pump (1) further includes a cannula (4) overlapping the enlarged diameter portion (15). The cannula (4) has a structure that prevents its distal end (42) from radially bending inwardly into the blood flow opening (16).

Description

[0001] Divisional application

[0002] This application is a divisional application of a patent application with an international filing date of February 10, 2017, an application number of 201780009523.4, a date of entry into the Chinese national phase of August 2, 2018, and an invention title of "Blood Pump". Background Art

[0003] The present invention relates to a blood pump, in particular an intravascular blood pump, for maintaining blood flow in a patient's blood vessel.

[0004] Different types of blood pumps are known, such as axial flow blood pumps, centrifugal blood pumps, or hybrid blood pumps in which blood flow is caused by both axial and radial forces. The intravascular blood pump is inserted into a patient's blood vessel, such as the aorta, through a catheter and into a heart valve. The blood pump generally includes a pump portion having a blood flow inlet and a blood flow outlet. In order to allow blood to flow from the blood flow inlet to the blood flow outlet, generally an impeller or rotor is rotatably supported within a pump housing about a rotation axis to pump the blood. The blood pump can be driven by an electric motor included within the blood pump adjacent to the pump portion, or alternatively, can be driven by an electric motor outside the patient, in which case the electric motor is connected to the impeller by a flexible drive shaft extending through the catheter.

[0005] The blood pump can be connected to a fluid cannula that is in fluid communication with the pump portion and can extend through a heart valve, such as the aortic valve, while the pump portion or at least the blood flow outlet of the pump portion is located in a blood vessel, such as the aorta, outside the patient's heart. The fluid cannula has at least one blood flow opening for allowing blood to enter the fluid cannula and move towards the blood flow inlet of the pump portion. Since the blood flow opening of the fluid cannula is located within the patient's heart (such as the left ventricle), soft tissues (such as filaments in the left ventricle) may be sucked into the blood flow opening. This situation should be avoided for several reasons. On the one hand, damage to soft tissues should be avoided. On the other hand, if the blood flow opening is blocked, this results in a malfunction of the blood pump and the blood pump has to be removed or at least repositioned. Summary of the Invention

[0006] The object of the present invention is to provide a blood pump that provides improved blood flow conditions at the blood flow inlet, in particular at the blood flow opening of the fluid cannula.

[0007] This object of the present invention is achieved by a blood pump having the features of independent claim 1. Preferred embodiments and further developments of the present invention are detailed in the dependent claims.

[0008] According to the present invention, a blood pump includes a fluid cannula, such as an inflow cannula, the proximal portion of the fluid cannula being connected to the pump portion such that blood can enter the blood flow inlet of the pump portion. The distal portion of the fluid cannula includes an enlarged diameter portion and at least one radial blood flow opening for allowing blood to enter the fluid cannula. At least a majority of the blood flow openings are provided in the enlarged diameter portion. The blood pump further includes a cannula having a proximal end attached to the proximal portion of the fluid cannula (particularly its distal portion) proximal to the blood flow opening, and a distal end covering or overlapping the enlarged diameter portion.

[0009] The cannula has a structure that at least prevents the distal end from radially bending inwardly into at least one blood flow opening by more than 0.2 mm during unobstructed operation of the blood pump in a patient. Unobstructed operation of the blood pump means the operating state during unobstructed, normal, and routine conditions in a patient, such as the operation of a blood pump with a flow rate of about 4 to 5 liters per minute. Preferably, the cannula has a reinforcing structure that prevents the cannula from collapsing during operation of the blood pump, as described in more detail below.

[0010] The above features, particularly their combination, can improve blood flow at the blood flow inlet of the pump, particularly at the blood flow openings of the fluid cannula, which are typically located within the patient's heart during operation of the blood pump. In other words, the blood pump of the present invention provides improved inflow characteristics. In particular, it is possible to prevent tissue, such as filaments in the left ventricle of the patient's heart, from being sucked into the blood flow openings, which would block the openings. This situation has already been improved by providing the enlarged diameter portion of the fluid cannula, but it is significantly improved by providing a cannula that covers or overlaps the enlarged diameter portion, i.e., particularly covers a portion of the blood flow openings. Further improvement of the inflow characteristics can be achieved by providing the cannula with a structure or reinforcing structure that prevents the cannula from collapsing and being sucked into the blood flow openings during operation of the blood pump. Additionally, the reinforcement keeps the cannula in a tapered shape and thus allows the blood velocity to gradually increase as blood enters the distal end of the cannula. Furthermore, by providing a cannula that guides the blood flow towards the blood flow openings, the amount of blood sucked into the blood flow openings, i.e., the flow rate, can be increased.

[0011] According to one aspect, at least the distal portion of the fluid cannula can radially expand from a compressed or collapsed configuration to an expanded configuration. In particular, the expanded configuration can define the enlarged diameter portion, and in the compressed or collapsed configuration, the diameter of the enlarged diameter portion can be substantially the same as the diameter of the rest of the fluid cannula, which can also be expandable or can have a fixed diameter. Providing the expanded configuration of the enlarged diameter portion helps to avoid tissue suction into the fluid cannula and enhances blood hydrodynamics, while the compressed or collapsed configuration allows the blood pump to be delivered through a guiding sheath. To provide the expansion characteristics, the distal portion of the fluid cannula can include a shape memory alloy material, such as Nitinol.

[0012] It should be noted that increasing the inflow diameter of the cannula results in a reduction in suction at the inflow cannula and a reduced extent to which the tissue in the suction inflow region affects blood flow into the cannula. In other words, assuming the same flow and pressure conditions in the inflow region, the tissue that sucks in a cannula with a smaller diameter will have a much greater impact on the flow entering the cannula than the same amount of tissue that sucks in a cannula with a larger diameter.

[0013] The distal portion of the fluid cannula, particularly the enlarged diameter portion, and more particularly, the expandable enlarged diameter portion, may include a framework structure defining blood flow openings, such as a cage. The framework structure may define a plurality of struts that preferably extend axially, i.e., generally in the direction of the longitudinal axis of the fluid cannula. It should be understood that other designs of the struts are possible, such as radial struts, helical struts, or struts angled with respect to the longitudinal axis, or combinations thereof. At least one blood flow opening may be provided on the radially circumferential surface of the distal portion of the fluid cannula. Radial openings are preferred over axial openings as they reduce tissue suction.

[0014] Preferably, the cannula includes a membrane of a flexible material, the flexible material preferably being polyurethane or any other suitable biocompatible material, particularly a polymer. The membrane may have a thickness of about 0.05 to 0.3 mm, such as 0.1 mm. As for the dimensions of the cannula in the longitudinal direction, the cannula may extend along at least a portion of the enlarged diameter portion of the corresponding blood flow opening, e.g., along half of the enlarged diameter portion. For example, the distal end of the cannula may be disposed generally at the maximum diameter of the enlarged diameter portion, or between the proximal end of the cannula and the maximum diameter of the enlarged diameter portion. Preferably, the cannula is disposed around the circumferential surface of the distal portion of the fluid cannula. In an alternative embodiment, the cannula may be disposed inside the fluid cannula, particularly within the framework structure.

[0015] The cannula may have a funnel shape to direct blood flow into the blood flow openings of the fluid cannula. That is, the diameter of the cannula increases towards its distal end to provide a conical shape. In particular, it is advantageous if the cannula tapers only in one direction, i.e., its diameter does not decrease after reaching the maximum diameter. The funnel shape is particularly useful for increasing the amount of blood sucked into the blood flow openings as the linear blood velocity gradually increases as the blood enters the funnel-shaped structure. For example, the flow rate may increase by 0.5 liters per minute compared to a blood pump without a cannula.

[0016] According to one aspect, the cannula can be configured to radially expand or deploy and collapse, preferably the cannula can be configured to radially expand or deploy and collapse due to blood flow. In particular, the cannula can include an expansion mechanism that allows the cannula to expand or deploy and collapse. The expansion mechanism can include, for example, at least one hinge, at least one magnet, shape memory alloy, or bimetal. Additionally or alternatively, such an expansion mechanism can be included in the fluid cannula, particularly in its enlarged diameter portion, and more particularly in the aforementioned frame structure.

[0017] The cannula can include a guiding structure at the inner surface of the cannula, such as at least one or more stator vanes. The guiding structure can prevent the blood flow from rotating and generating eddies that would dissipate the potential energy of the blood, and can guide the blood flow in the longitudinal direction.

[0018] According to one aspect, as briefly outlined above, the blood pump can include a reinforcement structure that provides increased stiffness in the radial direction to prevent radial collapse of the cannula. That is, the reinforcement structure ensures that during operation of the blood pump, at least in the region where the reinforcement structure is provided, the cross-sectional area of the cannula in a plane perpendicular to the longitudinal axis is convex, for example circular. Generally, a "convex" cross-sectional area means that the cross-sectional area has only radially outwardly curved or straight edges that do not form any depressions, undercuts, or radially inwardly curved portions relative to the plane perpendicular to the longitudinal axis. Preferably, the reinforcement structure is provided at least in or near the distal end of the cannula. In other words, it is advantageous or even sufficient if the open end of the cannula (i.e., the end where blood enters the cannula) is reinforced such that it does not collapse during operation of the blood pump but remains open to allow blood to enter the blood flow opening of the cannula and the fluid cannula. However, it should be understood that the reinforcement structure can still be collapsible, particularly for inserting or removing the blood pump through a catheter, as described in more detail below. That is, during operation of the blood pump, the reinforcement can resist any forces generated, particularly radial forces, such that the cannula does not collapse. However, if a sufficiently large force is applied, for example, during removal of the blood pump or during preparation of the blood pump before insertion into a catheter, the radial stiffness of the reinforcement structure can be overcome to cause the cannula to collapse or fold into a collapsed configuration.

[0019] Thus, according to one aspect, the reinforcement structure can radially expand or deploy from a collapsed configuration to an expanded configuration, which allows the blood pump to be delivered through a guiding sheath. Preferably, the reinforcement structure is conversely also collapsible or foldable to facilitate removal of the blood pump from the patient's body. Additionally, the reinforcement structure can simultaneously provide sufficient stiffness in the expanded configuration to prevent the cannula from collapsing during operation of the blood pump. However, the reinforcement structure can be designed such that it can be collapsed by applying a sufficiently large force, for example, by pulling the blood pump into a catheter for removal from the patient's body.

[0020] In one embodiment, the structure of the cannula, or in particular the reinforcement structure, may include at least one expandable structure that extends at least partially circumferentially around the cannula. The reinforcement structure may for example include at least one annular balloon. The balloon may be provided on the outer surface of the cannula such that it projects radially outward from the cannula and helps to keep soft tissue away from the blood flow opening. Alternatively or in addition to the annular balloon, the entire cannula may be expandable, or may include a reinforcement cannula and structures that are not just annular to prevent the cannula from collapsing. Further expandable structures may be provided with fluid intubation to increase stiffness or to keep soft tissue away from the access opening. For example, a soft end that may be expandable, such as a pigtail or J-tip, may be provided at the distal end of the cannula. It should be understood that any of the above expandable structures may also be contractible to facilitate removal from the patient's body.

[0021] Alternatively or additionally, the structure of the cannula, or in particular the reinforcement structure, may include at least one elastic member that extends at least partially circumferentially around the cannula. For example, the reinforcement structure may include at least one band or wire that extends at least partially circumferentially around the cannula and includes at least one of a shape memory alloy, a metal, and a polymeric material. The band or wire may extend along a straight line or in a corrugated or serrated shape circumferentially around the cannula.

[0022] Alternatively or additionally, the structure of the cannula, or in particular the reinforcement structure, may include at least one telescopic member that extends at least partially circumferentially around the cannula. The telescopic member may for example include a tube portion and a wire portion attached to the end of the tube portion such that the free end of the wire portion can be inserted into the free end of the tube portion to form a telescopic loop. The telescopic member may be made of a shape memory alloy, such as nitinol.

[0023] In one embodiment, at least two cannulas, such as two, three, or four cannulas, may be arranged in series on the distal portion of the fluid intubation such that blood can enter each of the cannulas towards the blood flow opening. For example, the cannulas may be arranged such that the proximal end of one cannula is disposed in the region of the distal end of an adjacent cannula, and blood can enter the distal end of each cannula. Alternatively, the distal end of one cannula may be connected to the proximal end of an adjacent cannula by a structure that provides an opening such that blood can enter each cannula from the distal end. The cannulas may be arranged in the manner of pinecone scales or may form a shape similar to a caterpillar track. Description of the Drawings

[0024] The foregoing Summary of the Invention and the following Detailed Description of the Preferred Embodiments will be better understood when read in conjunction with the accompanying drawings. To illustrate the present disclosure, reference is made to the accompanying drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings. In the drawings:

[0025] Figure 1 A partial cross-sectional view of a patient's heart with one embodiment of a blood pump is shown.

[0026] Figures 2A to 2C Shows Figure 1 different views of the end of the blood pump in a first configuration.

[0027] Figure 3A and Figure 3B Shows Figure 1 different views of the end of the blood pump in a second configuration.

[0028] Figure 4A and Figure 4B Shows Figure 1 different views of the end of the blood pump in a third configuration.

[0029] Figure 5A and Figure 5B Shows different views of the end of a blood pump according to another embodiment.

[0030] Figure 6 Shows a side elevation view of the end of a blood pump according to another embodiment.

[0031] Figure 7 Shows a reinforcing member for a cannula.

[0032] Figure 8 Shows a side elevation view of the end of a blood pump according to another embodiment, including more than one cannula.

[0033] Figure 9 Shows a side elevation view of the end of a blood pump according to another embodiment.

[0034] Figure 10A and Figure 10B Shows the inflow cage of the end of a blood pump according to another embodiment.

[0035] Figure 11A and Figure 11B Shows the inflow cage of the end of a blood pump according to another embodiment.

[0036] Figure 12A and Figure 12B Shows different views of the inflow cage of the end of a blood pump according to another embodiment. DETAILED DESCRIPTION

[0037] In Figure 1 , the blood pump 1 is shown as being inserted into the patient's heart 100. More specifically, the blood pump 1 is connected to a catheter 10 through which the blood pump 1 is inserted via the aorta 101 into the left ventricle 105 of the patient's heart 100. The aorta 101 includes a descending aorta 102 and an aortic arch 103. During operation, the blood pump 1 is positioned to pass through the aortic valve 104. The blood pump 1 includes a pump portion 2 and a fluid cannula 3. The pump portion 2 has a blood flow outlet 12 which is disposed outside the patient's heart 100 in the aorta 102, and the blood flow inlet (designated as 11) of the pump portion 2 is in fluid communication with the fluid cannula 3. An impeller (not shown) is provided to cause blood flow. The fluid cannula 3 extends through the aortic valve 104 into the left ventricle 105, and the fluid cannula 3 has a proximal portion 14 connected to the pump portion 2 and a distal portion 13. In order to pump blood through the fluid cannula 3 into the pump portion 2 and out of the blood flow outlet 12, the distal portion 13 has an enlarged diameter portion 15 with a blood flow opening 16, which will be described in more detail below. At the distal end of the blood pump 1, a soft tip 20, such as a pigtail tip or a J-shaped tip, is arranged to facilitate insertion of the blood pump 1 into the patient's heart 100 without causing any damage to the surrounding tissue. Also, the soft tip 20 helps to keep soft tissue away from the fluid cannula 3. The end portion of the blood pump 1 is shown as EP, which is shown in more detail in Figure 2A . Generally, the term "proximal" refers to the direction towards the user, while the term "distal" refers to the direction away from the user.

[0038] See Figures 2A to 2C , which shows in more detail the distal portion EP in a first configuration during operation of the blood pump 1, i.e., under normal conditions (including heart pressure and flow, e.g., a flow rate of 4 liters per minute). The blood flow opening 16 is formed by a frame structure, such as a cage, which includes struts 17 that separate the blood flow openings 16 from each other. In the present embodiment, the struts 17 are shown as extending generally axially along the longitudinal axis 18 of the fluid cannula 3. It should be understood that the struts 17 may also extend radially or helically, or may form any other suitable shape to form the blood flow openings 16. In the present embodiment, five struts 17 form a cage with the blood flow openings 16. However, there may be fewer struts, such as three or four, or more struts, such as six, seven or eight.

[0039] A cannula 4 is provided that covers a portion of the enlarged diameter portion 15 of the distal portion 13 of the fluid cannula 3, and more specifically, covers a portion of the blood flow opening 16 or overlaps therewith. The cannula 4 has a proximal end 41 and a distal end 42, and the proximal end 41 is attached to the distal portion 13 of the fluid cannula 3 at a position proximal to the blood flow opening 16. That is, the cannula 4 covers the proximal portion of the blood flow opening 16, such as the proximal half of the blood flow opening 16. By providing the cannula 4, the tissue sucked into the blood flow opening 16 can be reduced. The cannula 4 has a funnel shape, that is, its diameter increases in the direction from the proximal end 41 to the distal end 42. Preferably, the cannula 4 does not narrow at its distal end 42. The funnel shape can increase the blood flow of the blood pump 1.

[0040] As Figure 2A and Figure 2B shown, the cross-sectional area of the cannula 4 in a plane perpendicular to the longitudinal axis 18 is substantially circular. As shown, the cannula 4 can be supported by a cage. However, the cannula 4 can form a larger diameter than the cage. Under certain desired conditions, the cannula 4 can remain open by the blood flow during the operation of the blood pump 1 and can provide sufficient stability to resist collapse. This can be achieved by selecting a suitable material for the cannula 4 or by providing a reinforcing structure as described in more detail below.

[0041] During the operation of the blood pump 1, the cannula 4 can assume other configurations than substantially circular. As Figure 3A and Figure 3B shown, the cannula 4 can be closely fitted around the struts 17 such that if the cage includes five struts 17, the cross-sectional area of the cannula forms a pentagon. In particular, as Figure 4A and Figure 4B shown, due to the pressure distribution at the distal end 42 of the cannula 4, the cannula 4 can also bend slightly inward from the struts 17 into the blood flow opening 16. It should be understood that the bending inward on each side should not be greater than 0.2 mm to avoid an adverse effect on blood flow. In particular, the cannula 4 has sufficient stiffness to prevent it from being sucked into the blood flow opening 16, and such suction may block the blood flow opening 16.

[0042] Generally, the cage and the cannula 4, and possibly also the fluid cannula 3 can provide dilation characteristics. That is, the above-mentioned parts of the blood pump 1 can assume a dilated configuration that provides an enlarged diameter, and a collapsed or compressed configuration that provides a smaller diameter. In particular, the enlarged diameter portion 15 can be defined in the dilated configuration, and in the compressed configuration, the diameter of the portion 15 can be substantially the same as the diameter of the rest of the fluid cannula 3 to allow the blood pump 1 to be delivered through a guiding sheath. When delivered to the target location (such as the patient's heart as described above in connection with Figure 1 ), the blood pump 1 can be released to assume the dilated configuration.

[0043] Although the cannula 4 can have a structure that provides sufficient radial stiffness to prevent the cannula 4 from collapsing during operation of the blood pump 1, for example, a structure including a membrane of a suitable material such as polyurethane, an additional reinforcing structure attached to or embedded in the cannula 4 can still be provided. It should be understood that during operation of the blood pump 1, the reinforcing structure provides radial stiffness but also provides the expansion and compression characteristics as described above to allow the blood pump to assume an expanded or deployed configuration, as well as a compressed or collapsed configuration.

[0044] See Figure 5A and Figure 5B , the cannula 4 has a reinforcing structure in the form of an inflatable device such as an annular balloon 30. The balloon 30 can be inflated using a conduit (not shown) with a suitable fluid, such as a gas or a liquid, and can also be deflated. The balloon 30 can be attached to the outer periphery of the distal end 42 of the cannula 4, or can be attached to the balloon 30 at any other suitable location, or can be embedded in the cannula 4. Additionally, more than one inflatable annular balloon can be provided, or other inflatable structures that provide radial stiffness to the cannula 4 can be provided. Preferably, the inflatable structure is also collapsible to facilitate removal of the blood pump 1 from the patient's body.

[0045] Figure 6 and Figure 7 show further embodiments of reinforcing structures that can be used in place of or possibly in addition to the inflatable balloon 30. In Figure 6 , a reinforcing structure formed by a band 31 is shown, the band 31 including a shape memory alloy such as nitinol. For example, the band 31 can include nitinol wires in a serrated configuration. However, the band 31 can include other structures that provide radial stiffness during operation of the blood pump 1 and also provide expansion and compression characteristics, or can include other materials such as metals or polymers.

[0046] Figure 7 , the reinforcing structure shown is formed by a telescoping member 32. The telescoping member 32 includes a tube portion 34 and a wire portion 33 attached to the tube portion 34, where the free end of the wire portion 33 is slidably inserted into the tube portion 34 to form a telescoping loop. The telescoping member 32 provides radial stiffness to the cannula 4 but allows for a change in the diameter of the cannula 4 to allow for the expanded and compressed configurations as described above. The band 31 and the telescoping member 32 can be attached to the cannula 4 at the distal end 42 of the cannula to keep the distal end 42 open. However, it should be understood that the band 31 and the telescoping member 32 can be attached to or embedded in the cannula 4 at other suitable locations to provide the above-described characteristics.

[0047] Figure 8An embodiment is shown in which more than one, here three cannulas 4', 4'', 4''' overlap corresponding blood flow openings 16', 16'', 16''' formed by struts 17', 17'', 17'''. The blood flow openings 16', 16'', 16''' and the struts 17', 17'', 17''' can be formed respectively as the blood flow opening 16 and the strut 17 as described above. Similarly, the cannulas 4', 4'', 4''' can be formed as the cannula 4 as described above with or without additional strengthening structures. Such an arrangement can help keep soft tissue away from the blood flow openings.

[0048] Figure 9 Another embodiment of the distal portion EP of the blood pump is shown. In this embodiment, the cannula 40 is disposed inside the cage rather than around the cage. That is, the cannula 40 overlaps the blood flow opening 16 from the inside. Blood can enter the cannula 40 and thus enter the fluid cannula 3 without sucking in soft tissue. The soft tissue is kept away from the open end of the cannula by the strut 17. Additionally, the cannula 40 can be attached to the inner surface of the strut 17 (not shown) by an adhesive or any other means to keep the cannula 40 always open, or alternatively, the cannula 40 can be Figure 9 shown away from the strut 17. A reinforced inflatable toroidal balloon similar to the Figure 5A and Figure 5B shown in the balloon 30 ( Figure 9 not shown in ) can be used as described above to keep the cannula 40 open and in a circular shape during device use. A telescoping member similar to the Figure 7 shown in the telescoping member 32 ( Figure 9 not shown in ) can be used as described above to keep the cannula 40 open and in a circular shape during device use.

[0049] Figure 10A and Figure 10B show the inflow cage of the end portion of the blood pump according to another embodiment. This embodiment is generally similar to the previously described embodiment, where the same reference numerals denote the same elements. For the purpose of illustration, the cannula is omitted in Figure 10A and Figure 10B . The inflow cage forming the enlarged diameter portion 15 includes four struts 17 and blood flow openings 16. The inflow cage further includes a support structure for providing additional support to the cannula. The support structure can extend from the proximal end of the inflow cage for about half or less than half of the length of the inflow cage, or can correspond to the length of the cannula.

[0050] The support structure includes an arcuate portion 19 that connects adjacent struts 17, namely, four arcuate portions 19 in this embodiment. The arcuate portion 19 can have any suitable shape, such as pointed, circular, or other curved shapes, and can have a fork-like shape. The arcuate portion 19 can be disposed radially inwardly relative to the strut 17, or, as Figure 10A shown, disposed at approximately the same radius as the strut 17, or, as Figure 10B shown, can extend radially outwardly beyond the strut 17. In one embodiment, Figure 10A the configuration shown in can be referred to as a compressed configuration, while Figure 10B the configuration shown in can be referred to as a dilated configuration. The inflow cage can be made of a shape memory alloy such as nitinol.

[0051] Figure 11A and Figure 11B show an inflow cage of the end portion of a blood pump according to another embodiment, which is substantially the same as the embodiment shown in Figure 10A and Figure 10B . The inflow cage can be made of nitinol and can provide different configurations, such as compressed and dilated. As Figure 11A shown, the arcuate portion 19 is disposed radially inwardly relative to the strut 17, while in Figure 11B the strut is disposed radially outwardly relative to the strut 17.

[0052] Figure 12A and Figure 12B show different views of an inflow cage of the end portion of a blood pump according to another embodiment, which is similar to the embodiment shown in Figure 10A and Figure 10B . The inflow cage includes five struts 17 that are substantially the same as the struts in other embodiments. The inflow cage includes a support structure for providing additional support to the cannula (the cannula is not shown in Figure 11A and Figure 11B ). The support structure includes additional struts 19” having fork-shaped portions 19' toward the proximal end, such that the additional struts 19” bifurcate into separate branch portions 19”'. Referring to the embodiment shown in Figures 10A to 11B , the fork-shaped portion 19' can be considered as the arcuate portion 19, whereby the additional struts 19” are connected to the free distal ends of each of the arcuate portions 19. Or in other words, Figure 12A and Figure 12B the inflow cages of the embodiments can be considered to have multiple struts 17 and 19”, whereby at least some of the multiple struts bifurcate or branch toward their proximal ends to form a support structure for the cannula. As Figure 12A and Figure 12B shown, the branch portions 19”' of the respective struts 19” can be connected to adjacent struts 17. As in the above embodiments, the inflow cage is preferably made of nitinol.

[0053] It should be understood that the described embodiments are illustrative only and not restrictive. In particular, aspects and features of the embodiments can be combined or used independently in different embodiments. For example, the features described regarding the sleeve and the reinforcing structure can be variably combined without departing from the scope of the present invention.

Claims

1. A blood pump (1) comprising a pump section (2) and a fluid cannula (3), said pump section (2) having a blood flow inlet (11) and a blood flow outlet (12) and an impeller for transporting blood from said blood flow inlet (11) to said blood flow outlet (12), and said fluid cannula (3) having a longitudinal axis (18) and having a distal portion (13) and a proximal portion (14), wherein, The proximal portion (14) of the fluid cannula (3) is connected to the pump portion (2) such that blood can enter the blood flow inlet (11), and the distal portion (13) of the fluid cannula (3) includes an enlarged diameter portion (15) and at least one radially extending blood flow opening (16) for allowing blood to enter the fluid cannula (3), wherein at least a majority of the at least one blood flow opening (16) is disposed in the enlarged diameter portion (15). The blood pump (1) further includes a cannula (4) having a proximal end (41) attached to the proximal portion of the fluid cannula (3) proximal to the blood flow opening (16) and a distal end (42) overlapping the enlarged diameter portion (15), the cannula (4) having a structure that prevents the distal end (42) from radially inwardly bending into the at least one blood flow opening (16) by more than 0.2 mm during unobstructed operation of the blood pump (1) in a patient. The distal end of the cannula is generally disposed at the maximum diameter of the enlarged diameter portion.

2. A blood pump (1) comprising a pump section (2) and a fluid cannula (3), said pump section (2) having a blood flow inlet (11) and a blood flow outlet (12) and an impeller for transporting blood from said blood flow inlet (11) to said blood flow outlet (12), and said fluid cannula (3) having a longitudinal axis (18) and having a distal portion (13) and a proximal portion (14), wherein, The proximal portion (14) of the fluid cannula (3) is connected to the pump portion (2) such that blood can enter the blood flow inlet (11), and the distal portion (13) of the fluid cannula (3) includes an enlarged diameter portion (15) and at least one radially extending blood flow opening (16) for allowing blood to enter the fluid cannula (3), wherein at least a majority of the at least one blood flow opening (16) is disposed in the enlarged diameter portion (15). The blood pump (1) further includes a cannula (4) having a proximal end (41) attached to the proximal portion of the fluid cannula (3) proximal to the blood flow opening (16) and a distal end (42) overlapping the enlarged diameter portion (15), the cannula (4) having a structure that prevents the distal end (42) from radially inwardly bending into the at least one blood flow opening (16) by more than 0.2 mm during unobstructed operation of the blood pump (1) in a patient. The cannula is disposed around a circumferential surface of the distal portion of the fluid cannula.

3. A blood pump (1) comprising a pump section (2) and a fluid cannula (3), said pump section (2) having a blood flow inlet (11) and a blood flow outlet (12) and an impeller for transporting blood from said blood flow inlet (11) to said blood flow outlet (12), and said fluid cannula (3) having a longitudinal axis (18) and having a distal portion (13) and a proximal portion (14), wherein, The proximal portion (14) of the fluid cannula (3) is connected to the pump portion (2) such that blood can enter the blood flow inlet (11), and the distal portion (13) of the fluid cannula (3) includes an enlarged diameter portion (15) and at least one radially extending blood flow opening (16) for allowing blood to enter the fluid cannula (3), wherein at least a majority of the at least one blood flow opening (16) is disposed in the enlarged diameter portion (15). Wherein, the blood pump (1) further includes a cannula (4), the cannula (4) having a proximal end (41) attached to the proximal end of the fluid cannula (3) proximal to the blood flow opening (16), and a distal end (42) overlapping with the enlarged diameter portion (15), the cannula (4) having a structure that prevents the distal end (42) from radially bending inwardly into the at least one blood flow opening (16) by more than 0.2 mm during unobstructed operation of the blood pump (1) in a patient. Wherein, the cannula includes a guiding structure at the inner surface of the cannula for guiding blood flow in a longitudinal direction.

4. The blood pump according to claim 3, wherein the guiding structure comprises a plurality of stator vanes.

5. A blood pump (1) comprising a pump section (2) and a fluid cannula (3), said pump section (2) having a blood flow inlet (11) and a blood flow outlet (12) and an impeller for transporting blood from said blood flow inlet (11) to said blood flow outlet (12), and said fluid cannula (3) having a longitudinal axis (18) and having a distal portion (13) and a proximal portion (14), wherein, The proximal portion (14) of the fluid cannula (3) is connected to the pump portion (2) such that blood can enter the blood flow inlet (11), and the distal portion (13) of the fluid cannula (3) includes an enlarged diameter portion (15) and at least one radial blood flow opening (16) for allowing blood to enter the fluid cannula (3), wherein at least most of the at least one blood flow opening (16) is provided in the enlarged diameter portion (15). Wherein, the blood pump (1) further includes a cannula (4), the cannula (4) having a proximal end (41) attached to the proximal end of the fluid cannula (3) proximal to the blood flow opening (16), and a distal end (42) overlapping with the enlarged diameter portion (15), the cannula (4) having a structure that prevents the distal end (42) from radially bending inwardly into the at least one blood flow opening (16) by more than 0.2 mm during unobstructed operation of the blood pump (1) in a patient. Wherein, the structure of the cannula includes at least one of the following: - A reinforcing structure, the reinforcing structure having increased stiffness in a radial direction to provide a convex cross-sectional area of the cannula in a plane perpendicular to the longitudinal axis at least in the region where the reinforcing structure is provided. - At least one inflatable structure that at least partially circumferentially extends around the cannula. - At least one annular airbag. - At least one elastic member that at least partially circumferentially extends around the cannula. - At least one band or wire that at least partially circumferentially extends around the cannula, and the at least one band or wire includes at least one of a metal and a polymer material. - At least one telescopic member that at least partially circumferentially extends around the cannula.

6. A blood pump (1), comprising a pump part (2) and a fluid cannula (3), the pump part (2) having a blood flow inlet (11) and a blood flow outlet (12) and an impeller for transporting blood from the blood flow inlet (11) to the blood flow outlet (12), and the fluid cannula (3) having a longitudinal axis (18) generally having a distal part (13) and a proximal part (14), wherein, The proximal portion (14) of the fluid cannula (3) is connected to the pump portion (2) such that blood can enter the blood flow inlet (11), and the distal portion (13) of the fluid cannula (3) includes an enlarged diameter portion (15) and at least one radial blood flow opening (16) for allowing blood to enter the fluid cannula (3), wherein at least most of the at least one blood flow opening (16) is provided in the enlarged diameter portion (15). Wherein, the blood pump (1) further includes a cannula (4), the cannula (4) having a proximal end (41) attached to the proximal end of the fluid cannula (3) proximal to the blood flow opening (16), and a distal end (42) overlapping the enlarged diameter portion (15), the cannula (4) having a structure that prevents the distal end (42) from radially bending inwardly into the at least one blood flow opening (16) by more than 0.2 mm during unobstructed operation of the blood pump (1) in a patient. Wherein, at least two cannulas are arranged in series on the distal portion of the fluid cannula such that blood can enter each of the cannulas toward the blood flow opening.

7. The blood pump according to any one of claims 1 to 6, wherein the blood pump is an intravascular blood pump.

8. The blood pump according to any one of claims 1 to 6, wherein the blood pump is an axial flow blood pump, a centrifugal blood pump or a hybrid blood pump.

9. The blood pump according to any one of claims 1 to 6, wherein the distal part of the fluid cannula includes a frame structure defining the blood flow opening.

10. The blood pump according to claim 9, wherein the frame structure includes a plurality of struts, the plurality of struts extending generally in the direction of the longitudinal axis of the fluid cannula.

11. The blood pump according to claim 5, wherein the convex cross-sectional area is a convex circular cross-sectional area.

12. The blood pump according to claim 6, wherein three sleeves are arranged in series on the distal part of the fluid cannula.

13. The blood pump according to claim 5, wherein when the at least one band or wire includes metal, the metal includes a shape memory alloy.

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