The present invention resides in the field of mechanics or micromechanics and can be applied advantageously in particular in medical technology.

The invention relates to a blade for a pump and the design thereof. Of concern thereby is a pump having a rotor, the rotor being compressible and expandable in order to be able possibly to change the overall dimensions of the pump. In this way, the pump can be pushed through not readily accessible openings or into narrow pipe systems, for which purpose it is firstly compressed and, after it has been moved to the location of use, is expanded again.

Such a pump can be used particularly advantageously in medical technology in the field of heart pumps or other pumps for body fluids which are normally used with catheters.

In the technical medical field, different types of micropumps are known, which pumps can be introduced in the compressed state with a catheter through a naturally occurring body vessel into the body of a patient and can be expanded in situ. In order to produce a corresponding radial compressibility and expandability, various effects can be used in the construction and the structure of the pump housing and the pump rotor, such as e.g. the use of so-called memory alloys which change their shape as a function of the ambient temperature or control the pump diameter specifically by providing specific transmission mechanisms which allow it.

A solution is known from DE 10 2004 054 714 A1 in which both the impeller of a micropump and the housing thereof is manipulated by a mutual axial displacement of the pump drive shaft. As a result, the housing is changed between a compressed and an expanded state.

A system is known from the patent document WO 00/2003103745 A2, in which the pump housing is likewise expanded mutually radially by an axial relative movement of two components.

A rotor is known from the US patent specification U.S. Pat. No. 7,393,181, the blade of which can be subdivided into a plurality of partial blades or rows of partial blades for improved compressibility/collapsibility. As a result of the subdivision, the individual partial blades are smaller than a one-part blade and almost flat so that they can be rolled in easily. However, the ability to be subdivided is restricted by the intrinsic stability of the partial blades which requires to be ensured.

With the background of the state of the art, the object underlying the present invention is to produce a rotor which can be produced as simply and economically as possible or a blade for such a rotor, high compressibility being paramount with as little as possible of a force expenditure so that, in order to withdraw the pump from the vessel, the compression of the pump rotor can be achieved without greater external resistances. In addition, the corresponding pump is intended to be designed to be efficient and low-consumption.

The object is achieved according to the invention by the features of patent claim1.

The invention provides a blade having a plurality of lamellae which are disposed adjacently, are moveable relative to each other and pivotable relative to an axis of rotation of the rotor, the lamellae abutting against each other in the expanded state of the blade such that they form together a continuous blade surface.

Due to their pivotability, lamellae of this type can be pivoted individually very easily into a space-saving state and, in the pivoted-out, expanded state of the blade or of the rotor, form a closed blade surface which is designed such that it fulfils the required technical flow conditions with respect to shape and surface design.

Relative to a collapsible membrane, the blade consisting of individual lamellae has the advantage that its components can, both in the compressed and in the expanded state, assume a defined shape and arrangement. The individual lamellae can respectively be mounted rotatably on the shaft of the rotor and in fact advantageously pivotable in a plane which includes the longitudinal axis of the rotor shaft or an axis parallel to such a shaft, the mounting points being able to extend around the rotor shaft in a spiral in order to produce a spiral blade in the unfolded state. However, also other types of mounting are conceivable, in which the lamellae are mounted for example on one or more webs or transverse spars which are connected, for their part, to the rotor shaft.

The individual lamellae can be of equal length but can also be designed to be of different lengths according to which final shape the blade is intended to assume. The pivotability of the individual lamellae is restricted so that these, in the opened state, can withstand the flow counterpressure of a fluid to be conveyed. However, the lamellae can also be mutually supported in that they abut against each other and possibly engage in each other forming a lock. For example, the lamellae can be designed in the manner of the elements of a bird feather, the quill of the feather corresponding comparatively to the rotor shaft.

The construction of the blade can be designed such that the blade expands during rotation in the operating direction due to the fluid counterpressure and, when rotating in the opposite direction, is compressed by the effect of the medium in which the blade moves. This makes the compression- and expansion movement particularly simple without greater forces requiring to be overcome. During application in the medical field, such a pump can hence be removed again in a simple manner and without the danger of damaging body vessels.

A particular embodiment of the invention provides that at least two lamellae, in particular each of the lamellae, have per se a dimensionally stable, in particular rigid configuration.

The blade obtains its flexibility not from the flexibility of a membrane but from the movability of the individual lamellae relative to each other. For this purpose, the lamellae must not exceed a specific width. Advantageously, the blade for example can consist of at least 10 or at least 50 lamellae. Such a blade can have in total a very small constructional size in order to be inserted into a blood vessel, preferably less than 5 mm for example in the compressed state, a diameter of 2 mm.

A further advantageous embodiment of the invention can provide that respectively adjacent lamellae abut against each other to form a seal along a longitudinal side which extends at least partially radially relative to the rotor axis.

If it is even conceivable that the lamellae leave intermediate spaces between themselves, then the efficiency of the fluid pump in fact increases with the seal of the blade formed by the lamellae. It is therefore advantageous if the lamellae abut against each other respectively on their longitudinal side and as far as possible leave no intermediate space there.

It can be provided in addition that respectively lamellae which are mutually directly adjacent abut against each other in such a manner that they are not pivotable relative to each other about the rotor axis in at least one direction. Hence, the individual lamellae can support each other mutually and, during operation, entirely withstand the counterpressure of the fluid to be pumped. In particular if the lamellae are distributed in a spiral on the circumference of the rotor shaft, support is provided in the azimuthal direction.

The invention can be designed in addition such that respectively adjacent lamellae mutually overlap in the region of the longitudinal side. As a result of overlapping of the lamellae, particularly high impermeability is produced and, in addition, the support function of the lamellae can be mutually exerted in the overlapping region.

Particularly high stability and impermeability between the lamellae is achieved in that respectively adjacent lamellae engage one in the other in the region of the longitudinal side. Any type of form-fitting design of adjacent lamellae can thereby be provided, for example respectively the provision of a fold along the longitudinal sides of the lamellae, for example also in the form of a thin sealing lip.

In order to produce a form-fitting and sealed connection, it can also be provided that at least one lamella, in particular all the lamellae, have a convex shape, in cross-section, on one of the longitudinal sides thereof and a concave shape on the other longitudinal side. The corresponding convex or concave structure can, in cross-section, be round, elliptical or also configured as a groove or notch.

Advantageously, respectively adjacent lamellae can be connected to each other by a flexible element, in particular a strip or a membrane. The ability of the blade to be opened out is then produced in the manner of a fan, in the case of which broad, rigid support bars are connected to each other by narrow membranes or strips.

In order to stabilise the individual lamellae these can respectively have a stiffening structure in cross-section, which provides for example a web extending in the longitudinal direction. However, it can also be provided that, additionally or alternatively, the individual lamellae are configured to be hollow with a round or square cross-section.

Advantageously, the invention can be configured by a blade in which at least two lamellae are connected to each other by a chain-like connection. Such a chain-like connection consists of small hook-like elements on the one side and blade-like elements on the respectively other side, which can be configured advantageously to be microscopically small.

The invention can furthermore be designed advantageously in that the connection is detachable by applying a load on the blade in the axial direction of the rotor and/or by a relative movement of two adjacent lamellae along their respective longitudinal sides and in the longitudinal direction of the lamellae.

The longitudinal direction of the lamellae is thereby dictated by the direction in which the respective lamella extends away from the rotor shaft.

As a result of the described structure of a blade for the rotor of a fluid pump, said blade can be designed to be particularly stable and compressible in a defined manner, as a result of which in particular good compressibility and a small final diameter of the rotor can be achieved in the compressed form.

A development provides that a compressible and expandable blade for the rotor of a fluid pump, in particular a catheter pump, is provided, at least two lamellae which are disposed adjacently being pivotable respectively relative to an axis of rotation of the rotor and being moveable relative to each other and abutting against each other in the expanded state in such a manner that they form together a continuous blade surface, the at least two adjacently-disposed lamellae belonging to different rotor segments, one rotor segment comprising at least one lamella and also a hub segment.

As a result, it becomes possible to construct a rotor “sequentially”, layering of individual rotor segments hereby being provided in the axial direction. These rotor segments need not be (but might) welded etc. to each other, it suffices that these are fixed non-rotatably relative to each other. As a result of the fact that the rotor segments have respectively at least one lamella and also one hub segment, the connection to the rotor shaft can be provided by the hub segment or the hub segment can also represent an axial portion of the rotor shaft itself. By means of the combination of different hub segments, an influence can be made on the pitch of the helix. Hence, the economical construction of a helix with an irregular pitch becomes possible, the pitch increasing advantageously in the conveying direction.

The rotor segments can be made of different materials, for example from shape memory materials, in particular shape memory metals or shape memory plastic materials. In addition to “Nitinol”, polymers with the desired properties are hereby possible.

A development hereby provides that the lamellae per se are respectively individually coated and/or covered by a membrane, a connection of the coating/membrane of two adjacent lamellae being at best frictional and/or form-locking. As a result, the advantage of the “bird feather” principle is ensured, on the one hand, that the placing-around of individual lamellae frictionally (in particular when introducing into a lock) is associated with low complexity, however, on the other hand (due to the mutual support effect), a high fluid counterpressure can be produced. As a result of the fact that the individual lamellae per se (or specific groups of lamellae combined) are respectively coated individually or are covered with a membrane, it is achieved that, in the boundary region of a plurality of lamellae/lamella groups, an even better sealing effect is produced, on the one hand, by the coating/membrane and, in addition, better flow-wise or biocompatible adaptation of the blade to the medium to be conveyed (e.g. blood) becomes possible. In addition, this can mean weight and stability advantages since the lamellae per se require for example a metal frame which is then coated or sprayed over with a plastic material membrane or a polymer matrix. This is a significant improvement relative to lamella arrangements in which the entire blade, as a whole, is reshaped with a single membrane or a single spraying-around since such arrangements, during compression, require higher forces because of the limited deformability of the grouped lamellae.

A particularly advantageous development provides that the at least one lamella and also the hub segment of the rotor segment are in one part. This means that these can be produced integrally or from a unified body, preferably a pipe or a flat material (raw material). The thickness of the raw material is preferably 5 μm to 500 μm, more preferably 20 μm to 200 μm.

A development provides that at least two adjacent rotor segments are connected to each other non-rotatably in a form-fit. This can be ensured by corresponding engagement elements (raised portions/depressions). As a result, the mounting is significantly simplified in addition. One development provides that an individual rotor segment has here a single hub element and also one, two (or even more) lamellae. For example, the rotor segment can have an individual lamella, however also a “wing arrangement” is conceivable in which two lamellae (preferably situated one opposite the other) protrude. Various arrangements are possible here, above all according to how much lamella surface area is required. If in particular a lot of lamella surface area is required, a flat material or even a pipe material for example with a large diameter can be chosen, a diameter change then being able to take place later in the region of the hub segment for adaptation to the rotor shaft.

A method for the production of a rotor segment or a blade having a plurality of rotor segments provides that structures for hub segments and also lamellae are cut out (for instance by means of a laser by wire eroding or etching) from a (for instance tubular or flat) basic body, a connection web between hub segment and lamellae remaining in order to ensure the advantages of the one-part state. Subsequently, the lamellae can be plastically deformed in their radially protruding normal state by corresponding shaping tools, as a result of which they correspond to the expanded (but not yet subjected to fluid pressure) state of the subsequent blade. Subsequently, possibly a chemical etching treatment or a further laser treatment of the lamellae can be effected in order to ensure for example smooth or different surfaces in order to influence the technical flow properties of the lamella. For example, also the profile of the lamella can be adapted here to assist the flow.

Hereafter, the rotor segments can subsequently be joined axially to form a rotor shaft. Preferably, these rotor segments, even when a form-fit is provided in advance by complementary concavities/raised portions, are connected to each other by means of material joining methods, for example gluing or welding.

Another development provides that rotor segments with connection webs disposed between the rotor segments can be worked out of a flat material and are to be disposed on a rotor shaft by folding the flat material out of the surface plane in such a manner that automatically a helix shape of the blade is produced.

A further development provides that a plurality of lamellae are part of one lamella body, these being connected to each other merely in their foot region. As a result, again easy collapsibility of the lamellae is achieved since they are not connected in their end region protruding radially from the rotor (in the expanded state) and hence the lamellae can individually be deformed easily.

The lamella body can thus be introducible into a hub body such that, in the unloaded state of the outer tips of the lamellae, a helix shape of the blade is formed. For example, the hub body is configured as a shell with spiral longitudinal slots into which the lamella body is introduced so that later the hub body represents the outer circumference of the rotor shaft in the case of a finished catheter pump/fluid pump.

A further development provides that the lamella body in the foot region of the lamellae has weak portions in order to achieve higher tangential deflections of the lamellae with the same force application (compared with the state in which there are no weak portions). As a result, good rigidity of the lamella is achieved, on the one hand, relative to the fluid but, on the other hand, sufficient flexibility is ensured during the first deformation of the lamella body into the helix shape.

All of the above-mentioned lamella arrangements make it possible to produce catheter pumps for introduction into human vessels, in particular for intraventricular use, a rotor with a blade and the pump having a conveying direction for conveying body fluid and the blade hereby having a flow pressure side and a flow suction side.

A development provides that, on the flow pressure side, the proximal region of a distal lamella covers the distal region of an adjacently-situated proximal lamella. As a result, the type of “stepping” of the lamellae is fixed. The advantage is that a stepping of this kind is very blood-compatible. The erythrocytes do not collide with the step in pumping/flow direction; instead, they “fall down the steps”.

In one embodiment it is possible to finish, to coat and/or to extrusion coat/insert mold the single lamellae in a way that (at least in regions) a steady/continuous curvature of the blade on the flow pressure side and/or the flow suction side is given.

A further development provides that application of the lamellae in a compressed state is effected essentially by deflecting the lamellae. This is achieve (for example in an embodiment according toFIG. 13d) in a way that proximally of the rotor a sheath is positioned and the rotor is introduced into the sheath in proximal direction, wherein the lamellae basically one after another (first the most proximal, then the one distally neighboring the most proximal and so on) are bent (i.e. the blades are not bent in total at once, instead the lamellae are bent one after another which has the advantage of lower force requirements). The sheath may have a tube-shape cross-section.

It is also possible to provide a compressible rotor housing etc. between sheath and rotor, without changing the above principle of bending the lamellae one after another. Remark: in the context of the patent application, “bending the lamellae basically one after another” means that especially the beginning (the first phase) of bending of the lamellae happens one after another. In the case of multi-blade rotors, eventually several lamellae having the same axial position are contemporaneously bent.

It may be noted once again that the above-described coating of individual lamellae or groups of lamellae can be effected with a membrane (plastic material- or metal foil) or any other coating.

The invention is shown and subsequently described in the following in a drawing with reference to an embodiment.

