AXIAL-FLOW PUMP FOR A VENTRICULAR ASSIST DEVICE AND METHOD FOR PRODUCING AN AXIAL-FLOW PUMP FOR A VENTRICULAR ASSIST DEVICE

Abstract

The invention relates to an axial flow pump (102) for a ventricular assist device. The axial flow pump (102) comprises a pump housing (104) for arranging in a blood vessel and a pump rotor (108), which is or can be mounted in the pump housing (104) for rotation about an axis of rotation and which consists of a hub (200) and at least one blade element (110) which is helically wound around the hub (200), at least in portions, and is provided for conveying, in the direction of the axis of rotation (302), a medium to be conveyed. In order to increase the pump efficiency, the blade element (110) has at least one blade section (202) having an undulating blade curvature.

Claims

1-18. (canceled)

19. A cardiac support system for insertion through a catheter into a blood vessel, comprising: an axial flow pump comprising: a tube-shaped pump housing having an axis of rotation extending therethrough; and a pump rotor extending in the pump housing and being rotatable about the axis of rotation, the pump rotor comprising a hub and a blade element, the blade element being wound at least in sections helically around the hub and configured to axially draw blood into the pump housing in a direction toward the hub; wherein the pump housing further comprises: a pump intake section upstream of the pump rotor and configured to receive the blood drawn into the pump housing, the pump intake section being penetrated by the axis of rotation; and at least one peripheral outlet opening configured to laterally discharge the blood drawn into the pump housing; and wherein the at least one blade element has a profile with camber lines, wherein a curvature of each of the camber lines when unwound into a plane increases along the axis of rotation in a direction starting from the pump intake section towards the outlet opening to an inflection point at which a blade angle (β) of the blade element is at a maximum, and wherein the curvature of each of the camber lines decreases after the inflection point; wherein, in a region of the pump rotor located radially relative to the axis of rotation and having a blade height SH of the at least one blade element defined relative to a maximum blade height SHMAX such that 25%≤SH/SHMAX≤100%, the inflection point of each of the camber lines is located in a region of an upstream edge of the outlet opening.

20. The cardiac support system according to claim 19, wherein the at least one blade element comprises at least one blade section having a wavy blade curvature.

21. The cardiac support system according to claim 20, wherein the at least one blade section having the wavy blade curvature is configured in a section of the pump rotor at least partially located in a housing section of the pump housing open to the at least one outlet opening.

22. The cardiac support system according to claim 20, wherein the wavy blade curvature varies in a direction of a radial extension of the at least one blade section.

23. The cardiac support system according to claim 20, wherein the wavy blade curvature increases with increasing radial distance from the axis of rotation.

24. The cardiac support system according to claim 20, wherein the at least one blade element has a thickness that changes along the axis of rotation in the at least one blade section having the wavy blade curvature.

25. The cardiac support system according to claim 19, wherein the hub faces a distal end of the cardiac support system.

26. The cardiac support system according to claim 19, wherein the hub has a diameter that increases along the axis of rotation in the direction starting from the pump intake region towards the outlet opening.

27. The cardiac support system according to claim 19, wherein the blade angle (β) is measured relative to a line perpendicular to the axis of rotation,

28. A cardiac support system for insertion through a catheter into a blood vessel, comprising: an axial flow pump comprising: a pump rotor being rotatable about an axis of rotation, the pump rotor comprising a hub and a blade element, the blade element being wound at least in sections helically around the hub and configured to axially draw blood into the pump in a direction toward the hub; at least one peripheral outlet opening configured to laterally discharge the blood drawn into the pump; and wherein the at least one blade element has a profile with camber lines, wherein a curvature of each of the camber lines when unwound into a plane increases along the axis of rotation in a direction starting from an upstream end of the rotor towards the outlet opening to an inflection point at which a blade angle (β) of the blade element is at a maximum, and wherein the curvature of each of the camber lines decreases after the inflection point; wherein, in a region of the pump rotor located radially relative to the axis of rotation and having a blade height SH of the at least one blade element defined relative to a maximum blade height SHMAX such that 25%<SH/SHMAX≤100%, the inflection point of each of the camber lines is located in a region of an upstream edge of the outlet opening.

29. The cardiac support system according to claim 28, wherein the at least one blade element comprises at least one blade section having a wavy blade curvature.

30. The cardiac support system according to claim 29, wherein the at least one blade section having the wavy blade curvature is configured in a section of the pump rotor at least partially located in a section of the pump open to the at least one outlet opening.

31. The cardiac support system according to claim 29, wherein the wavy blade curvature varies in a direction of a radial extension of the at least one blade section.

32. The cardiac support system according to claim 29, wherein the wavy blade curvature increases with increasing radial distance from the axis of rotation.

33. The cardiac support system according to claim 29, wherein the at least one blade element has a thickness that changes along the axis of rotation in the at least one blade section having the wavy blade curvature.

34. The cardiac support system according to claim 28, wherein the hub faces a distal end of the cardiac support system.

35. The cardiac support system according to claim 28, wherein the hub has a diameter that increases along the axis of rotation in the direction starting from the upstream end of the rotor towards the outlet opening.

36. The cardiac support system according to claim 28, wherein the blade angle (β) is measured relative to a line perpendicular to the axis of rotation,

Description

[0028] Advantageous design examples of the invention are schematically shown in the drawings and explained in more detail in the following description.

[0029] The figures show:

[0030] FIG. 1 a cardiac support system having an axial flow pump according to one design example;

[0031] FIG. 2 the axial flow pump of the cardiac support system of FIG. 1 having blade elements and having a hub in a side view;

[0032] FIG. 3 an unwinding of a blade element of the axial flow pump of FIGS. 1 and 2;

[0033] FIG. 4 a perspective partial view of the axial flow pump of FIGS. 1 and 2 with a blade element having a blade section with a wavy blade curvature and, for comparison, the geometry of a conventional blade element for an axial flow pump that does not have a wavy curved section;

[0034] FIG. 5 a view of the blade element of the axial flow pump shown in FIG. 1 and FIG. 2 with different blade heights relative to the surface of the hub;

[0035] FIG. 6 the profile of the blade angle β formed between the circumferential direction and a camber line of the blade element along a normalized meridional coordinate m/mMax;

[0036] FIG. 7 a flow diagram of a method for producing an axial flow pump according to one design example; and

[0037] FIG. 8 a schematic illustration of a device for carrying out and/or controlling the method of FIG. 7.

[0038] In the following description of favorable design examples of the present invention, the same or similar reference signs are used for the elements shown in the various figures, which have a similar effect, whereby a repeated description of these elements is omitted.

[0039] FIG. 1 shows a schematic illustration of a cardiac support system 100 having an axial flow pump 102 according to one design example. The cardiac support system 100 has a tube or hose-shaped configuration. The cardiac support system 100 is realized as an axial centrifugal pump system that can be placed into a blood vessel such as the aorta or a ventricle in a minimally invasive manner by means of a catheter. The axial flow pump 102 has an axis of rotation 302 and includes a pump housing 104 which is realized as a tube-shaped section of the cardiac support system 100 that surrounds the axis of rotation 302 and comprises, for example three, opposite lateral outlet openings 106 for laterally discharging a conveying medium, in this case blood. According to alternative design examples, the pump housing 104 comprises only one, two, three or even more than three outlet openings 106 distributed in circumferential direction. A pump rotor 108, also referred to as an impeller, is rotatably mounted in the pump housing 104 and, in the assembled state of the axial flow pump 102 shown in FIG. 1, said pump rotor is opposite to the outlet openings 106 in some sections. The pump rotor 108 serves to axially draw in and radially or diagonally expel the blood via the outlet openings 106.

[0040] To ensure the most efficient and gentle transport of the blood possible, the pump rotor 108 comprises at least one helically wound blade element 110. The camber line of the blade element 110 comprises an inflection point in the region of the upstream start of the outlet openings 106.

[0041] FIG. 2 shows a schematic illustration of the axial flow pump 102 of FIG. 1 in a side view. The blade element 110, which is wound helically around a hub 200 of the axial flow pump 102, can be seen. The hub 200 forms an inner core of the pump rotor 108. A flow direction of the conveying medium is schematically indicated with three arrows. The conveying medium is drawn in through a front-side inlet opening in the pump housing 104, which is upstream of the pump rotor 108 and functions as an intake opening.

[0042] According to this design example, the blade element 110 extends from an upstream end of the pump rotor 108 over an entire length or at least a majority of the hub 200. The hub 200 has a diameter that increases in the direction of flow, which results in a configuration of the hub 200 that becomes thicker in the direction of flow. This facilitates radial or diagonal discharge of the conveying medium.

[0043] The blade element 110 comprises a blade section 202 having a wavy blade curvature, which is defined by a multiple curvature of a camber line 204 of the blade element 110. A wavy blade curvature is to be understood here to be a change in the curvature of the blade section 202 associated with at least one change of sign.

[0044] As can be seen from FIG. 2, in the installed state of the pump rotor 108 at least one partial section of the blade section 202 is opposite to the outlet openings 106.

[0045] According to this design example, the blade section 202 is located at least partially in the region of a flow-facing edge 206 of the outlet opening 106. The blade section 202 represents a transition between a convex and a concave curvature.

[0046] As an example, the pump rotor 108 according to FIG. 2 comprises two blade elements 110, which are wound in the same direction around the hub 200 and each comprise the blade section 202. According to an alternative design example, the pump rotor 108 is realized with more than two such blade elements 110.

[0047] FIG. 3 shows a schematic illustration of the unwinding of a camber line 204 of a blade element 110 of FIGS. 1 and 2. Two pairs of blade angles α.sub.1d, β.sub.1 and α.sub.2, β.sub.2 are drawn in as an example, each of which represents a tangent slope of a tangent 300 representing the curvature of the camber line 204. Each tangent 300 is drawn into a cylindrical coordinate system with a z-axis parallel to an axis of rotation 302 of the pump rotor and a Φ-axis perpendicular to the z-axis.

[0048] The Φ-axis represents a circumferential direction of the pump rotor.

[0049] As can be seen from FIG. 3, the tangent slope initially increases in flow direction, indicated by a vertical arrow, and then decreases again. According to this design example, the tangent slope initially increases continuously from a blade leading edge 304 to a blade trailing edge 306 of the blade element 110 and, upon reaching the inflection point 310 of the camber line 204, decreases again. A point 308 marks a position of a flow discharge via the outlet openings of the pump housing, more precisely a start of the flow discharge in axial direction. The objective here is to ensure that the inflection point 310 and the point 308 of the start of the flow discharge are in close proximity.

[0050] As already described, according to one design example, the pump rotor is realized with at least two blade elements 110. The conveying medium is delivered axially to or is drawn in by the pump rotor and expelled radially and diagonally through one or more outlet openings in the pump housing. The blade elements 110 are configured such that the angle α between the tangent 300 formed with a blade surface or the camber line 204 and the axis of rotation 302 or the z-axis changes in axial direction. The angle β between the circumferential direction or the Φ-axis and the blade surface or the camber line 204 changes to the opposite extent. The angle β changes such that, at least in the region of the largest diameter of the pump rotor, i.e. in a section in the region of the blade tips of the blade elements 110, from the start of the pump rotor, i.e. from the blade leading edge 304, it increases in flow direction. The angle β in particular assumes its greatest value in the region of the start of the flow discharge 308 or in close proximity thereof, at least in the region of the largest diameter of the pump rotor, i.e. in a section in the region of the blade tips of the blade elements 110.

[0051] FIG. 4 shows a schematic illustration of the axial flow pump 102 of FIGS. 1 and 2 in perspective view. A region of the pump rotor 108 enclosed by the pump housing 104, in which the pump housing 104 has no outlet opening, is marked with a rectangle 400. The wavy blade curvature of the blade element 110, which is extended in a region enclosed by the pump housing 104 in which said housing has one outlet opening 106, is clearly visible. A conventional blade element 402 without a wavy blade curvature is drawn in next to the blade element 110 for comparison.

[0052] FIG. 5 is a view of the blade element of the axial flow pump shown in FIG. 1 and FIG. 2 with different blade heights relative to the surface of the hub of the pump rotor 108. Five horizontal lines representing different blade heights of the blade element 110 relative to a surface of the hub 200 are shown. A first line 501 represents 0 percent, a second line 502 represents 25 percent, a third line 503 represents 50 percent, a fourth line 504 represents 75 percent, and a fifth line 505 represents 100 percent of a maximum blade height.

[0053] FIG. 6 shows a diagram to illustrate a progression of the blade angle β of FIG. 3 along a normalized meridional coordinate m/mMax. With the aid of five curves, the progression of the blade angle β is shown for different blade sections as a function of the blade height of the blade element, i.e. of a radial distance of the camber line thereof from the hub. Analogous to FIG. 5, a first curve 601 corresponds to a section of the blade element along the first line 501 at the height of the hub at 0 percent blade height, a second curve 602 corresponds to a section of the blade element along the second line 502 at 25 percent blade height, a third curve 603 corresponds to a section of the blade element along the third line 503 at 50 percent blade height, a fourth curve 604 corresponds to a section of the blade element along the fourth line 504 at 75 percent blade height and a fifth curve 605 corresponds to a section of the blade element along the fifth line 505 at 100 percent blade height, i.e. on the blade tips at the maximum impeller diameter. The start of the flow discharge at the outlet openings of the pump housing is marked with a hatched region 606.

[0054] On the one hand, the diagram shows that the blade angle β, and thus the curvature of the camber line, has different progressions in flow direction depending on the radial distance from the hub. On the other hand, it can be seen that the blade angle β in the considered sections initially increases in the direction of flow and decreases again after a high point, which in this case represents a respective maximum of the curves or the blade angle β. The position of the high point along the meridional coordinate varies depending on the radial distance of the camber line from the hub.

[0055] According to FIG. 6, the reversal point for the 25 to 100 percent blade heights is either in or just before or just after the hatched region 606, the distance of which from the inlet opening of the pump housing 104 viewed in the direction of the axis of rotation 302 corresponds to the distance of the edge of the outlet opening 106 of the pump housing 104 facing the inlet opening of the pump housing 104. Therefore, with respect to a similar coordinate origin located on the axis of rotation 302, the side of the outlet opening 106 facing the inlet opening of the pump housing 104 and the region of the pump rotor 108 corresponding to the hatched area 606 have axial coordinates that correspond to one another, i.e. which are equal to one another or deviate from one another only slightly.

[0056] In contrast, the reversal point for the 0 percent blade height is clearly located in front of the hatched region 606, here in a region of the meridional coordinate between 10 and 20 percent.

[0057] According to one design example, the pump rotor has the high point in the blade angle β in the region of the start of the flow discharge via the outlet openings or even in close proximity to the flow discharge, but at least in the outer area at the blade tips. In this region there is therefore a change in the curvature of the camber line from concave to convex. This design of the blade element allows the swirl in the flow to be reduced, which enables efficient operation and, associated with this, gentle fluid conveyance with reduced damage.

[0058] FIG. 7 shows a flow diagram of a method 700 for producing an axial flow pump according to one design example, for example the axial flow pump described above with reference to FIGS. 1 to 6. In a step 710, the pump housing and the pump rotor having the hub and the blade element wound helically around the hub are formed. The blade element is configured at least in sections with a wavy blade curvature. In a further step 720, the pump rotor is arranged in the pump housing. The pump rotor is mounted such that it can rotate about an axis of rotation in order to convey the conveying medium in the direction of the axis of rotation.

[0059] FIG. 8 shows a schematic illustration of a device 800 for carrying out and/or controlling the method 700 of FIG. 7. The device 800 comprises a first unit 810 for forming the pump housing and the pump rotor and a second unit 820 for arranging the pump rotor in the pump housing.

[0060] If a design example includes an “and/or” conjunction between a first feature and a second feature, this should be read to mean that the design example according to one embodiment comprises both the first feature and the second feature and, according to another embodiment, comprises either only the first feature or only the second feature.

[0061] In summary, the following features of the invention should in particular be noted: An axial flow pump 102 for a cardiac support system comprises a pump housing 104 for arrangement in a blood vessel and a pump rotor 108 which is or can be mounted in the pump housing 104 such that it can rotate about an axis of rotation and consists of a hub 200 and at least one blade element 110 which is wound at least in sections helically around the hub 200 for conveying a conveying medium in the direction of the axis of rotation 302. To increase the pump efficiency, the blade element 110 comprises at least one blade section 202 having a wavy blade curvature.

[0062] The invention in particular relates to the aspects specified in the following clauses: [0063] 1. Axial flow pump (102) for a cardiac support system (100), wherein the axial flow pump (102) has the following features: [0064] a pump housing (104) for arrangement in a blood vessel; and [0065] a pump rotor (108) which is or can be mounted in the pump housing (104) such that it can rotate about an axis of rotation (302) and consists of a hub (200) and at least one blade element (110) which is wound at least in sections helically around the hub (200) for conveying a conveying medium in the direction of the axis of rotation (302), wherein the blade element (110) comprises at least one blade section (202) having a wavy blade curvature. [0066] 2. Axial flow pump (102) according to Clause 1, in which the blade element (110) is defined by one or more camber lines (204), each having at least one inflection point, and/or a locally variable thickening, in particular wherein a tangent slope of a tangent (300) representing a curvature of the camber line (204) initially increases in the direction of flow and decreases again after the inflection point to produce the wavy blade curvature. [0067] 3. Axial flow pump (102) according to any one of the preceding clauses, in which an outer surface of the pump housing (104) comprises at least one outlet opening (106) for lateral discharge of the conveying medium, wherein in the installed state of the pump rotor (108), the blade section (202) is at least partially opposite to the outlet opening (106). [0068] 4. Axial flow pump (102) according to Clause 2 and 3, in which the inflection point of at least one camber line is located in the region of the outlet opening (106), in particular in the region of a flow-facing or upstream edge (206) of the outlet opening (106). [0069] 5. Axial flow pump (102) according any one of Clauses 2 to 4, in which the blade element (110) is wound helically around the hub (200) starting from a beginning (304) of the pump rotor (108), wherein the tangent slope increases starting from the beginning (304) of the pump rotor (108) and decreases again after the inflection point. [0070] 6. Axial flow pump (102) according to any one of the preceding clauses, in which the wavy blade curvature varies in the direction of a radial extension of the blade section (202). [0071] 7. Axial flow pump (102) according to any one of the preceding clauses, in which the wavy blade curvature increases with increasing distance from the axis of rotation (302). [0072] 8. Axial flow pump (102) according to any one of the preceding clauses, in which the hub (200) has a diameter which increases in the direction of flow. [0073] 9. Method (700) for producing an axial flow pump (102) for a cardiac support system (100), wherein the method (700) comprises the following steps: [0074] forming (710) a pump housing (104) for arrangement in a blood vessel and a pump rotor (108) which consists of a hub (200) and at least one blade element (110) which is wound at least in sections helically around the hub (200) for conveying a conveying medium, wherein the blade element (110) comprises at least one blade section (202) having a wavy blade curvature, and [0075] arranging (720) the pump rotor (108) in the pump housing (104), wherein the pump rotor (108) is mounted such that it can rotate about an axis of rotation (302) in order to convey the conveying medium in the direction of the axis of rotation (302). [0076] 10. Device (800) comprising units (810, 820), which are configured to carry out and/or control the method (700) according to claim 9. [0077] 11. Computer program, which is configured to execute and/or control the method (700) according to Clause 9. [0078] 12. Machine-readable storage medium, on which the computer program according to Clause 11 is stored.