Radially compressible and expandable rotor for a fluid pump

Abstract

Radially compressible and expandable rotor for a fluid pump (2) with a hub (4) and at least one conveying element (10, 11, 19, 20) which has a plurality of struts and at least one membrane (18) which can be tensioned between them, wherein at least a first group of struts (12, 13, 14, 15, 16, 21, 22, 27, 28) is pivotable in a pivot plane starting from a common base (17) and can thus be expanded in a fan-like manner and wherein the conveying element, in the expanded state, rests against the hub along its entire length, characterized in that various struts (12, 13, 14, 15, 16, 21, 22) with different lengths are provided.

Description

[0001] The present invention lies in the field of mechanical engineering and microtechnology and is particularly concerned with conveying devices for liquids and fluids in general.

[0002] Such conveying devices are already known in a wide variety of forms as pumps with various conveying principles. Of particular interest in this context are rotary-driven pumps with rotors that convey fluids radially or axially.

[0003] Such pumps are subject to a wide range of requirements regarding rotor bearings, resistance to environmental influences, and interaction with the fluids being pumped. Particularly when pumping fluids containing complex, biologically active molecules, e.g., within living bodies, special demands are placed on the relative velocity between the respective pumping elements and the fluid, as well as on turbulence and shear forces.

[0004] A special area for such pumps is in the field of microtechnology for use in invasive medicine, where pumps are manufactured in such a small design that they can be moved through body vessels and brought to their place of use.

[0005] Such pumps are already known for their function as heart-supporting pumps, which can be guided through blood vessels in a patient's body into a heart chamber and operated there.

[0006] In order to optimize the efficiency of such pumps, it is already known to equip these pumps with compressible and expandable rotors that are radially compressed during transport through a blood vessel and can only be expanded within a larger body space, for example in a heart chamber.

[0007] The design requirements for such compressible and expandable rotors are very high, particularly due to their small size and biocompatibility as well as the requirements for reliability.

[0008] A corresponding compressible rotor is known, for example, from US 6,860,713. Another such pump is known from US 7,393,181 B2.

[0009] To make the rotors compressible, it is common practice to use bodies or frameworks that can be deformed either elastically or super-elastically, for example made of so-called shape-memory alloys such as Nitinol, which may be covered with a membrane, so that the corresponding rotors can be easily elastically compressed radially and can be erected or expanded for operation either automatically or with the aid of pulling mechanisms.

[0010] Rotors are also known that can be expanded during operation by fluid back pressure or by centrifugal forces.

[0011] In addition, various mechanisms are known by which blades can be folded down, bent or radially attached to corresponding hubs in a similar manner.

[0012] In such complex designs, it is important to ensure that the conveying surfaces of a corresponding conveying element are as smooth as possible in order to achieve high efficiency, that the angle of the conveying surface can be optimized with respect to the rotation axis, and that the rotation speed can be selected within a reasonable range.

[0013] In addition, the compression and expansion mechanism must be designed in such a way that it functions reliably, that the pump is stable during operation and that the pump can be reliably compressed and transported in the compressed state.

[0014] Against the background of these requirements and the state of the art, the present invention is based on the object of creating such a pump which functions reliably and can be compressed and expanded easily and reliably while maintaining good efficiency.

[0015] The object is achieved according to the invention with the features of patent claim 1.

[0016] In order to create a radially compressible and expandable rotor for a fluid pump with a hub and at least one conveying element which has a plurality of struts and at least one membrane which can be tensioned between them, and in order to make the corresponding rotor particularly simple and reliable to compress and expand, the invention provides that at least a first group of struts can be pivoted in a pivoting plane starting from a common base and can thus be stretched out in a fan-like manner and that the conveying element in the expanded state rests against the hub over its entire length.

[0017] The surface of the conveying element is thus formed by the membrane stretched between the struts, and this can be folded together in a fan-like manner for transport, whereby the struts take up significantly less space radially in the folded state than in the stretched state. The word "fan" [note: "fan" in the English original of the PCT application] here refers to the essentially two-dimensional structure, in the meaning of the German word "Fächer" [note: German in the original], which preferably looks like a classic Chinese or Spanish fan, i.e. preferably a structure consisting of a plurality of struts that are held together at one end but are freely movable at the other end. At least some of the struts, in particular all of the struts, can converge in a fan-like manner at a common base and be pivotally mounted there in a suitable form.In this case, the struts can be clamped completely to one side of the hub at a fan angle of 90°, or to both sides up to the hub, for example, at an angle of 180°, so that the conveying element ideally rests against the hub on both sides of the base. This achieves particularly good efficiency in the conveying of fluids by minimizing pressure equalization processes of the fluid between the conveying element and the hub.

[0018] In order to minimize the space required by the impeller element or several impeller elements, if two or more impeller elements are provided on the hub, in the compressed state, for example during transport of the fluid pump, it can advantageously be provided that the hub has a first recess in which at least the first group of struts or even all of the struts are at least partially accommodated in the compressed state. The hub can generally be cylindrical or cylindrically symmetrical.

[0019] In this way, a radially particularly small and, depending on the proportion of struts that can be accommodated within the recess, also smooth contour of the hub is realized, which allows easy displacement, for example, within a blood vessel.

[0020] Advantageously, a common pivot axis for several struts can also be arranged in the area of ​​the first recess. In this case, the struts can be easily pivoted out of the recess for operation of the pump at the installation site.

[0021] A particularly space-saving solution can be achieved if the pivot axis passes through the first recess and runs tangentially to the circumferential direction of the hub. In this case, the pivoting part of the struts pivots out of the recess, while a section of the struts opposite the bearing point can move within the recess.

[0022] It can prove particularly advantageous if two conveying elements, each with a group of fan-shaped struts, are provided, which lie opposite one another on the circumference of the hub and, particularly in the compressed state, are at least partially accommodated in a recess in the hub. In this case, two conveying elements can be arranged symmetrically on the hub to achieve good efficiency. Depending on the shape of the conveying elements, which can be provided as flat surfaces, for example, inclined relative to the rotor axis, or which can also have a helical shape, it can be provided that different conveying elements rotate around the hub in a mutually offset manner.

[0023] In this case, several recesses can be provided on the circumference of the hub. In the case of two conveyor elements, for example, two recesses are provided that are diametrically opposite each other on the circumference of the hub and can also be combined to form a continuous opening in the hub. This makes the recess in the hub particularly easy to manufacture and also provides sufficient space for the struts to pivot within the recess.

[0024] Furthermore, it can advantageously be provided that each of the conveying elements, in the expanded state, rests against the hub on both sides of the respective recess. In this case, the struts of the conveying element can be pivoted on both sides to such an extent that they cover an angle of 180° along the hub and axially cover both sides of the recess, if one is provided, or a corresponding pivot point if the conveying element is mounted on the hub surface, and lie tightly against the peripheral surface of the hub.

[0025] To achieve optimal axial conveying and high rotor efficiency, it is advantageous for the membrane to be inclined at least partially relative to the rotor axis in the expanded state. Depending on the angle that the membrane or the conveying surface of the conveying element forms relative to the rotor's longitudinal axis, a helical orbit of the membrane around the hub is also provided. However, a flat membrane shape can also be provided.

[0026] An advantageous embodiment of the invention can also provide that at least one strut is angled out of the pivot plane of the struts at least over part of its length relative to other struts.

[0027] By bending or angling individual or groups of struts, any desired three-dimensional shape of the membrane / conveying surface of the conveying element can be realized that is favorable in terms of flow and conveying efficiency. For example, the struts can be bent or angled accordingly at the end opposite the pivot axis or on the half of their length farther from the pivot axis, so as not to impede or hinder insertion into the recess of the hub in the area of ​​the pivot axis.

[0028] A particularly simple embodiment of the rotor according to the invention provides that at least the struts of the respective fan-shaped group are pivotably mounted on a shaft within the respective recess. The provision of a corresponding shaft in the recess represents a particularly simple and durable solution for pivotally mounting the struts.

[0029] However, it is also possible for the pivoting struts to be connected to one another at their base by film joints. For example, the struts can be made of the same material and formed as a single piece, such as an injection-molded material. In this case, the membrane can be applied, for example, by immersing the struts in a liquid plastic, such as polyurethane. However, it is also conceivable to manufacture the membrane from the same material as the struts, with the thickness of the membrane being designed accordingly. In this case, the provision of film joints can be achieved by weakening the material in the areas where flexibility is desired.

[0030] To create an ideal outer contour of the impeller element, it may be useful or necessary to combine different struts of different lengths within the impeller element. The appropriate length of the struts may also depend, for example, on the shape of the housing in which the rotor rotates.

[0031] In addition, in order to increase the efficiency and to improve the stability of the rotor during operation, at least one receiving device, for example a rail, can be provided along the hub to receive the outer struts of the conveying element in the expanded state.

[0032] Accordingly, after expansion and fan-like tensioning of the struts or tensioning of the membrane, the outermost struts, which extend axially from the base approximately parallel to the hub in one or both directions, can each be fixed in such a receiving device, which can, for example, be fork-shaped. The respective outermost strut on the hub can then be inserted into such a fork. The struts can also be fixed to the hub in another way, such as by magnets or by inserting them into a rail-like recess or elevation of the hub.

[0033] This ensures that the fluid to be pumped cannot flow between the pumping element and the hub during pressure equalization processes and that, on the other hand, the pumping element is given additional support and stability by the hub.

[0034] In the following, the invention is shown using an exemplary embodiment in a drawing and then explained in more detail. Fig. 1 schematically shows a view of a fluid pump when used as a cardiac catheter pump, Fig. 2 a rotor in a view in the compressed state, Fig. 3 an embodiment of a rotor in the expanded state, Fig. 4 a view of another embodiment of a rotor in the expanded state, Fig. 5 a side view of a rotor in the compressed state, Fig. 6 a view of the arrangement from Fig. 5 rotated by 90° around the rotor longitudinal axis, Fig. 7 a view as from the Fig. 5 and Fig. 6, shown three-dimensionally in an oblique view, Fig. 8 the arrangement from the Fig. 5, Fig. 6 and Fig. 7 in an axial plan view of the rotor, Fig. 9 a side view of the rotor from the Fig. 5 to 8 in expanded state, Fig. 10 the view from Fig. 9 rotated 90° around the longitudinal axis of the rotor, Fig. 11 an oblique view of the arrangement from the Fig. 9 and Fig. 10, Fig. 12 an axial plan view of the rotor from the Fig. 9 to 11, Fig. 13 a side view of a rotor with an inclined pivoting plane of the struts, Fig. 14 another embodiment with a fan and a fastening to the hub and Fig. 15 a three-dimensional view of the conveying element as a folded membrane.

[0035] Fig. Figure 1 schematically shows a fluid pump utilizing the rotor according to the invention, after insertion into a heart chamber 1. The pump 2 comprises a housing 3 and a hub 4 to which pumping elements are attached. The hub 4 is connected to a shaft 5, which is guided through a hollow catheter 6 within a blood vessel 7 and led out of the vessel and the patient's body via a sheath 8. The rotatable shaft 5 can be driven by a motor 9 at high speeds, for example, on the order of 10,000 rpm.

[0036] By means of the rotational movement transmitted to the hub 4 and the conveying elements of the pump, blood can be transported between the heart chamber 1 and the blood vessel, for example, sucked in by the pump 2 and pressed into the blood vessel 7.

[0037] The pump 2 may have a diameter or general dimensions in the operating state that would be too large to be transported through the blood vessel 7. For this purpose, the pump is radially compressible. Fig. 1 it is shown in the expanded state which it can assume after introduction into the heart chamber 1 by means of the hollow catheter 6.

[0038] The pump, together with the hollow catheter 6, is inserted in a compressed state through the blood vessel 7 until it protrudes into the heart chamber 1 before it is expanded.

[0039] Before removal, which occurs by pulling out the catheter 6, the pump 2 must be compressed again, which can be done, for example, by appropriate pulling elements not shown in detail, or, if the pump is only expanded by centrifugal forces, it is stopped and then collapses.

[0040] It is also conceivable to compress the pump at least to some extent by pulling it into the hollow catheter, for example by providing an insertion funnel at the distal end of the hollow catheter 6.

[0041] The shape of the hub 4 is in the Fig. 2, where the struts of the conveying element(s) are shown in the compressed state, i.e., in contact with the hub. The front end of the hub, facing the interior of the heart chamber 1, is designated 4a.

[0042] The struts can be placed so tightly against the hub that they take up only a tiny amount of space in the radial direction of the rotor. When compressed, the diaphragm is rolled or folded between the struts.

[0043] Fig. Figure 3 shows the at least partially expanded state of a rotor with the hub 4, wherein two conveying elements 10, 11 are provided, which are diametrically opposed to each other on the circumference of the cylindrical hub 4. Each of the conveying elements is essentially shaped like a quarter of an ellipse, so that the individual struts 12, 13, 14, 15, 16 cover an angular range of approximately 90° starting from the base 17. However, by varying the length of the struts, other shapes, for example, rectangular ones, can also be achieved.

[0044] In the expanded state, the membrane 18 is flat and taut between the struts 12 to 16. The conveying element 10 is located exactly opposite the conveying element 11 described in more detail, so that together with the hub 4 they form half an ellipse. The struts 16 closest to the hub 4 can be fixed or at least guided there, for example, with a receiving device. Such a receiving device can, for example, be U-shaped with two legs, so that the strut 16 can dip into the conveying element 11 when it expands and is held there if necessary. This ensures that there is virtually no space between the strut 16 and the hub 4, which, if it were present, could cause the fluid to flow out between the hub and the conveying element when the rotor rotates, thus causing a pressure loss.

[0045] The Fig. 4 shows two semi-elliptical conveyor elements 19, 20 opposite each other on the circumference of the hub 4, which are constructed with the help of struts in the same way as in the Fig. 3 and which are axially located on both sides of the respective base 17 on the hub 4 in such a way that a tight connection is provided between the hub and the conveying element. Each of the conveying elements covers, according to the Fig. 4 an angle of 180°. Here, too, other shapes, such as rectangular ones, can be achieved by varying the length of the struts. The conveyor elements made of Fig. 4 can also be made up of two conveyor elements according to Fig. 3, whereby in this case the respective pivot axes do not have to be identical.

[0046] The struts of a single conveyor element 19, 20 are quite different in length, so that the base 17 does not have to be axially in the middle of the conveyor element. As shown in the Fig. 4, for example, the strut 21 is shorter than the opposite strut 22.

[0047] The individual struts can, for example, be made of a plastic by injection molding technology, e.g. also connected at the base 17, wherein a membrane is stretched between the struts, either by immersing the struts in a liquid plastic or by producing the individual conveying elements 19, 20 as a whole from the same material in one piece, wherein the membrane is then provided as a film between the struts.

[0048] Fig. 5 shows a side view of a hub 4 with two recesses 23, 24 on both sides of the hub, which are connected through the hub to form a common opening.

[0049] Two shafts 25, 26 are mounted in this opening, on which the struts are pivotally mounted. In the compressed state, the individual struts are essentially located within the recesses 23, 24, as can be seen more clearly in the view of the Fig. 6, which is compared to the representation of Fig. 5 is rotated by 90° around the rotation axis 40.

[0050] From the Fig. 6 also shows that some of the struts 27, 28 are located in the common pivoting plane of the struts, which follows the course of the drawing plane in Fig. 5, are angled out slightly at least at their ends facing away from the pivot axis 25, 26. This design of the struts means that the struts cannot be completely accommodated in the recesses 23, 24, but it does result in a three-dimensional, optimized design of the conveyor element.

[0051] In the Fig. Figure 7 shows a three-dimensional representation of the rotor, which clearly shows the prominent angled ends of the struts.

[0052] Also the Fig. 8, which is an axial plan view of the rotor from the Fig. 5 to 7 clearly shows the projecting ends of the struts 27, 28 and the struts of the further conveyor element opposite them.

[0053] Fig. 9 shows in the expanded state of the rotor from the Fig. 5 to 8, how the angled struts 27, 28 cause the front edge of the conveying element to bend out of the plane of the membrane, resulting in a spiral-shaped structure of the conveying elements.

[0054] This is particularly evident from the Fig. 10 and 11 respectively. The Fig. 12 clearly shows in plan view that the membrane stretched between the struts is not in a flat form, but is curved.

[0055] Fig. Figure 13 illustrates, using another embodiment, that the struts 29, 30 can also be inclined with respect to their pivoting plane relative to the longitudinal axis / rotational axis 40 of the hub 4. This is possible, for example, by a corresponding inclination of the shaft 31, on which the struts 29, 30 are pivotably mounted, as shown in Fig. 13 shown.

[0056] Thus, even when a flat membrane is present between the struts 29, 30, a helical rotation of the conveying element / membrane around the hub 4 results, so that when the hub rotates, an axial propulsion of the fluid to be conveyed occurs.

[0057] The other pivot axis, which belongs to the opposite conveyor element, is then also inclined in a mirror-symmetrical manner to the pivot axis 31.

[0058] The Fig. Figure 14 shows a design of a conveyor element 32 in the form of a folded membrane, with the individual folds of the membrane, designated 33, 34, forming the struts. In the present example, the folds are parallel. However, they can also be angled to each other or curved.

[0059] The membrane can be clamped fan-shaped in a recess 35 of the hub 4 and folded axially to both sides of the hub, stretching the membrane. This results in a particularly simple manufacturing method for the conveying element.

[0060] The arrows 36, 37 indicate the folding movements of the conveying element against the hub 4 on both sides of the recess 35.

[0061] The Fig.15 shows again in isolation the conveying element 38 as a bent membrane with the kinks / struts 33, 34 before installation in the recess 35 of the hub 4. The recess 35 can, for example, be introduced into the hub as a slot, wherein the slot can also run obliquely or curved with respect to the longitudinal axis 27 in order to achieve a helical rotation of the conveying element around the hub.

[0062] The inventive design of a rotor with corresponding conveying elements creates a particularly cost-effective and simple method of manufacturing the conveying elements, which also allows for easy compression and expansion of the conveying elements. The space required by the rotor during transport into the operating position is minimized by the invention.

Claims

[1] Radially compressible and expandable rotor for a fluid pump (2) with a hub (4) and at least one conveying element (10, 11, 19, 20) which has a plurality of struts and at least one membrane (18) which can be tensioned between them, wherein at least a first group of struts (12, 13, 14, 15, 16, 21, 22, 27, 28) is pivotable in a pivot plane from a common base (17) and can thus be expanded in a fan-like manner and wherein the conveying element in the expanded state bears against the hub over its entire length, characterized by that different struts (12, 13, 14, 15, 16, 21, 22) with different lengths are provided. [2] Rotor according to claim 1, characterized by that a first recess (23, 24, 35) is provided in the hub (4), in which at least the first group of struts is at least partially received in the compressed state. [3] Rotor according to claim 1 or 2, characterized bythat a common pivot axis of several struts is arranged in the region of the first recess (23, 24, 35). [4] Rotor according to claim 3, characterized by that the pivot axis passes through the first recess (23, 24, 35) and runs tangentially to the circumferential direction of the hub (4). [5] Rotor according to claim 1 or one of the following, characterized by that two conveying elements (10, 11, 19, 20) are provided, each with a group of fan-shaped struts which are opposite one another on the circumference of the hub and are at least partially received in one recess (23, 24, 35) of the hub, in particular in the compressed state. [6] Rotor according to claim 1 or one of the following, characterized by that each of the conveying elements (10, 11, 19, 20) in the expanded state rests against the hub on both sides of the respective recess. [7] Rotor according to one of claims 1 to 6, characterized bythat the membrane (18) in the expanded state is inclined at least in sections relative to the rotor axis (40). [8] Rotor according to claim 7, characterized by that at least one strut (27, 28) is angled or curved out of the pivoting plane of the struts at least over part of its length with respect to other struts. [9] Rotor according to claim 1 or one of the following, characterized by that at least the struts of the group which can be expanded in a fan-like manner are pivotally mounted on a shaft (25, 26, 31) within the respective recess (23, 24, 35). [10] Rotor according to claim 5, characterized by that on the hub (4) two recesses (23, 24) are continuously connected to one another and form a through opening of the hub. [11] Rotor according to claim 1 or one of the following, characterized by that the pivotable struts (33, 34) are connected to one another at their base by film joints. [12] Rotor according to claim 1 or one of the following, characterized by that at least one receiving device, in particular a rail, is provided along the hub for receiving the outer struts (21, 22) of the conveyor elements (19, 20) in the expanded state.

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