BACKGROUND OF THE INVENTION

The invention resides in the mechanical field, and more particularly in the medical engineering field. It relates to pumps being equipped with pump rotors and having a pump housing, the interior of which accommodates the pump rotor. In particular in the medical engineering field, however, generally also in any other technical fields of application, pumps are known, which may be radially compressed in that both the rotor and the pump housing may be deformed in order to reduce the diameter, and which are expandable at the site after transport, in order to adjust to the measurements required for an optimized function. Further, in particular in the medical engineering field, such pumps are known, which may be compressed such that the same may be inserted into a blood vessel into the body of a patient, and may be expanded there, in order to support or independently enable the blood transport via the operation of the pump.

In order to ensure a reliable collapsibility and expandability, a plurality of technical problems must be solved.

For example, US Patent Specification U.S. Pat. No. 7,393,181 B2 describes a collapsible pump rotor, in which conveyor vanes are disposed in rows on a hub, and may be retractable on the same.

A pump rotor is known from U.S. Pat. No. 7,841,976 B2, which may be inserted into the expandable part of a cannula, in order to be operated there after the respective cannula part has expanded. For this purpose the rotor is driven via a shaft extending through the cannula. The pump formed in this manner may be advanced through a blood vessel all the way into a heart chamber, and operated at that location.

U.S. Pat. No. 7,927,068 B2 also describes a pump having a rotor, which has a hub and retractable and tiltable conveyor vanes. The conveyor vanes are pushed into the position suitable for the pump operation during the operation of the rotation by means of the fluid counter pressure created.

An intravascular pump having a collapsible and expandable housing is known from DE 100 59 714 C1, which has a mesh. This housing may accommodate a rotor, and may be inserted into a blood vessel by means of an insertion lock.

The prior art state above generally deals with the problems of compressing a pump having a rotor and a pump housing radially sufficient so that the same may, for example, be inserted into a blood vessel of a patient, and may be expanded after insertion. At a later time the respective pump should also be collapsible again in order to be able to be removed. In the compressing and expansion process both the rotor and the housing are commonly deformed correspondingly. A special challenge is found in the requirement of minimizing the pump gap, i.e. the intermediate space between the rotor, more specifically the radial external ends of the conveyor vanes, and the internal housing wall of the pump housing during operation, in order to optimize the pump operation, in particular the effectiveness and the compressing of the pump. The pump gap must be very small and, in particular, must be held as constant as possible in order to prevent any overflow at the radial external ends of the conveyor elements of a rotor, on the other hand the conveyor elements or other elements of the rotor should not contact the interior wall of the pump housing, if at all possible, in order not to generate any unnecessary friction losses or abrasion wear at the commonly high rotational speeds of more than 10,000 rotations per minute.

BRIEF SUMMARY OF THE INVENTION

Against this background of prior art the object of the present invention is therefore to create a pump housing and a pump of the type mentioned above, which allow an adjustment of the pump gap that is as accurate end reproducible as possible.

The object is achieved according to the invention with the characteristics of patent claim1, and/or the characteristics of patent claim11, and/or the characteristics of patent claim12.

Accordingly, the pump housing has a housing skin and at least one reinforcement element, wherein in the fully expanded state of the housing the housing skin is tightened in circumferential direction by means of the expansion of the reinforcement element, and wherein at least one element that is circumferential in circumferential direction in a stretch-resistant manner, is provided, which is tightened in the expanded state as opposed to the power-free state in circumferential direction less than 5%, in particular less than 1%, and which limits the further expansion of the pump housing.

The housing skin may consist of an easily deformable, flexible, in particular pliable plastic material, and may contain, for example, a polymer. The housing skin may be simply disposed about the reinforcement element, or may be connected to the same by means of common joining techniques, such as gluing or welding. The reinforcement element may also be integrated in the housing skin by means of casting.

Usually, the reinforcement element is configured and disposed such that it supports the housing skin radially from the interior. This is also possible in case of integration of the reinforcement element, for example via casting, into the housing skin.

With an expansion of the pump housing from a compressed state the reinforcement element or a group of reinforcement elements deform and tighten the housing skin, in that they exert a force which acts radially toward the exterior onto the same. The hydrodynamic, and in particular hemodynamic properties of the pump housing are particularly improved, if the housing skin is tightened, in particular tightened in a crease-free manner, and the interior wall of the pump housing limiting the interior for accommodating the pump rotor is as smooth as possible.

However, should this not lead to the fact that variable stretching forces are created by means of the forces acting upon the housing skin, depending on the size of the forces acting by means of the reinforcement elements such that the measurements of the interior of the housing vary. For this purpose the invention provides a stretch-resistant element revolving in circumferential direction, which may not be stretched in any essential manner by means of the forces acting radially toward the exterior of the reinforcement element(s). The stretch-resistance element is advantageously disposed in the axial section of the pump housing accommodating the pump rotor. For this purpose the stretch-resistant element may also cover the entire axial length of the pump rotor.

The stretchable element may also be a flexible film, which is, for example, substantially more stretch-resistant than the housing skin, and may radially surround the same.

The stretch-resistant film may also surround merely the reinforcement elements, may be radially surrounded itself by the housing skin, or may replace the housing skin.

The pump housing in turn advantageously comprises an axial section, in which the interior is formed essentially cylindrical. This cylindrically formed axial interior area may accommodate, for example, the pump rotor.

Such cylindrical form should also comprise approximately circular cylindrical shapes formed as polygonal prisms, or as polyhedrons, each inscribed to a circular cylinder, and which are created by the housing skin supports by means of bracers. The individual limiting surfaces, of which the forms consist, may be, for example, diamond-shaped.

The pump housing, or the interior thereof, respectively, may axially protrude more or less beyond the length of the pump rotor relative to the axial section provided for accommodating the pump rotor, for example, by at least 2 cm, in particular at least 5 cm, further in particular at least 8 cm. The area of the pump housing extending beyond the length of the axial section provided for accommodating the pump rotor may be positioned distally from the pump rotor, i.e. toward the end of the pump housing, an which the same has the suction side thereof with a suction opening. An ejection opening is provided for the fluid to be transported at the proximal end of the pump housing. However, the rotor may also at least partially protrude beyond the structure enclosed by a housing skin.

The suction opening of the pump housing may be, for example, an opening at the front side, which is advantageously covered by a suction cage. The suction cage may have the shape of, for example, a ball calotte, or may also initially provide an expansion via the diameter of the pump housing in a balloon shape, which is terminated toward the distal end by means of a calotte, or also by means of a point equipped with a pigtail. The suction cage may be formed by means of continuous reinforcement elements of the pump housing.

The pump housing may be cylindrically formed up to the suction end thereof, and may advantageously have a funnel-shaped expansion at the end on the suction side, from which the reinforcement elements exit and form a balloon-shaped expanded suction cage.

On the ejection side, or at the end at the ejection side, the pump housing advantageously also has an opening at the front. There, reinforcement elements can also exit from the wall of the pump housing and be guided to the central symmetry axis of the pump housing, wherein the same retain and center a catheter extending coaxially toward the pump housing with a smaller diameter than that of the pump housing, and may accommodate, for example, a drive shaft for a pump rotor.

The shape and size, as well as the pre-treatment of the reinforcement element(s) are advantageously selected such that the elastic forces of the reinforcement element(s) going beyond the actual radial expansion of the housing, are so large the excess forces directed radially toward the exterior are greater than 1 N, preferably 4 N. This means that even a radial force of the reinforcement elements that is reduced by the excess forces would still result in a full expansion of the housing.

In this manner it is ensured that the housing is not deformable, in particular is not collapsible with regard to the diameter of the interior, even by a certain limited radial pressure from the exterior (a maximum of the same size as the excess forces). In order to compress the pump housing, forces are necessary which exceed forces of the reinforcement elements that act at least radially from the inside.

In this manner it is ensured, in particular In case of a position of the pump housing in the aortic valve that with the closure of the valve the pump housing will not be compress, thereby jamming the rotor, or will not be decelerated upon contact at the pump housing. Such contact would result in the loss of pump performance, and also to the creation of friction and hematolysis, i.e. damage of blood due to acting shear and grinding forces.

The reinforcement element(s) may be composed, for example, of elastically collapsible bracers from metal or plastic, which are released for the expansion of the pump housing, and are elastically deformed. A reinforcement element may, for example, also be formed as an annular revolving element, such as an open circular ring, which revolves about the circumference of the pump housing, and may as a whole be deformed between a spiral-like wound, compressed state and an expanded state, in which it is expanded into a diameter enlarged by an annular ring or a winding.

It is also conceivable that the reinforcement element(s) form a vault, or an arch, respectively, expanding by means of pivoting individual elements against each other. In the forming of such a vault, or an arch, it may also be provided to engage the same into a self-stabilizing position in the expanded state.

An advantageous embodiment of the invention provides that the reinforcement element(s) resist forces directed toward the interior of at least 1 N, preferably 4 N, in the expanded state of the arch or vault formed by the housing, without compressing.

If the forces directed radially toward the interior significantly exceed this threshold, the vault or the arch caves in such that the pump housing reduces the exterior dimensions thereby by means of compression, and may again expand after the forces directed toward the interior are discontinued. The collapse of the arch or vault may be reversible or irreversible.

Another advantageous embodiment of the invention provides that the stretch-resistant element is formed by means of a pliable film, in particular by means of the housing skin.

It may also be provided that the stretch-resistant element is formed by means of a ring revolving in circumferential direction of the housing, surrounding the reinforcement element at least in sections. In particular, the stretch-resistant element may surround the reinforcement element(s) in that area, in which the pump rotor is accommodated.

Advantageously, it may also be provided that the stretch-resistant element is disposed on the radially external side of the housing skin.

For the stabilization of the stretch-resistant element, in particular of also of the entire housing skin, it may also be advantageously provided that the stretch-resistant element has stretch-resistant fibers extending in circumferential direction, in particular glass fibers or carbon fibers. Other fibers or reinforcement elements for improving the stretch resistance are also conceivable.

A particular embodiment of the reinforcement elements provides that the same form a surface-like, two-dimensional grate which is bent into the shape of a tube. The individual grate elements may advantageously be displaced against each other, and/or pivoted, or also elastically deformed, or bent, such that a deformation of the tube-shaped structure is easily possible. The reinforcement elements may revolve in the circumferential direction of the pump housing, for example, in the manner of a saw tooth, or in a meandering manner.

It may also advantageously be provided that multiple reinforcement elements being pivotable against each other form the shape of a tube in a first pivoting state, and are compressed radially as opposed to the tube shape in a second pivoting state. For this purpose the reinforcement element can be connected with each other, for example, at individual points, and form joints, wherein the joint function may be realized by means of hinge-type devices, but also by means of elastic deformation.

It may also be advantageously provided that the housing interior tapers in axial direction in a reducing manner, in particular in a conical manner. This opens up the possibility to axially displace the rotor to be incorporated in the housing interior far enough such that the housing gap, i.e. the intermediate space between the interior wall of the housing interior and the radially most externally positioned ends of the rotor, in particular of the feed elements of the rotor, are optimized, for example, minimized. For this purpose the cone angle of the housing interior may advantageously be between 0.5° and 5°, in particular between 0.5° and 2°.

In this regard, the exterior contour of the pump rotor may also advantageously taper conically as the housing interior, furthermore advantageously having substantially the same cone angle. During the operation of the rotor the same may then be axially displaced in the housing interior far enough until optimal pump performance is reached. This may be determined, for example, by means of a flow measurement, and/or in connection with a power reading of the drive motor of the pump rotor. For example, the rotor may be moved far enough until a marked deceleration occurs, which speaks in favor of the rotor contacting the interior wall of the housing interior, and the rotor may be returned about a defined axial distance, and fixed in this axial position.

However, the housing interior may also have a slightly convex (ball-shaped), or concave shape. This is of particular advantage, if the rotor has different exterior contours due to the deformation in the current field at different operational states (e.g. speed). Depending on the base form of the rotor, a housing form is necessary in this case, which meets the respective requirements of all operational states.

Regardless whether a conical rotor or a rotor having a cylindrical contour, and a housing interior in a conically tapering, or strictly cylindrical shape, are used, the pump gap should be between 0.01 mm and 1 mm, in particular between 0.01 mm and 0.3 mm, further advantageously between 0.03 mm and 0.15 mm. For this purpose the pump gap denotes the minimum distance between a most radially external end of a part of the rotor and the interior wall of the housing interior, which occurs with the rotation of the rotor. In any case, it should be advantageously ensured that the rotor will not contact the pump housing during normal operation.

In order to achieve an optimized compressibility and expandability of the pump housing, it may be advantageously provided that the reinforcement element(s) consist of a super-elastic material, in particular a super-elastic alloy, particularly nitinol. Such materials may be compressed very strongly without any problems, and may also be configured as memory materials, in particular memory alloys, which assume a previously selected form, for example, with the occurrence of a certain temperature change, or of a target temperature.

In addition to a pump housing of the type described above, the invention also relates to a blood pump with a respective pump housing, and with a rotor.

The rotor may consist of, for example, plastic, in particular polyurethane, and advantageously also of foam. It has one or more conveyor elements conveying a liquid in radial and/or axial direction with regard to the rotational axis. The conveyor elements may be embodied as paddles, or as a single continuous paddle, wherein the single paddle, or a series of paddles, revolves about a central hub in the manner of a helix.

Also, two conveyor vanes revolving in a screw-type manner may be provided. The conveyor vanes may be embodied in a self-supporting manner without a hub, or they may be attached on a central hub, or may be integral with the same. Advantageously, the hub and the conveyor elements may consist of the same material.

The conveyor elements may be embodied such that they may be folded in for the compression on the hub, and may be folded out for the expansion. In particular, the conveyor elements assume a center position in the powerless and idle state of the rotor, which neither corresponds to the compressed position, nor the expanded position. In order to assume the compressed position, a radial pressure is applied to the conveyor elements from the exterior, in order to abut the same closely to a hub. The radial pressure may be applied, for example, by means of the compression of the housing surrounding the rotor.

If the radial pressure is reduced, the conveyor elements sit up straight for a distance. Another straightening may be effected by means of the fluid counter-pressure at the beginning of the rotation of the rotor in the fluid to be transported.

The conveyor elements are typically embodied such that they have been straightened to a maximum in radial direction during the operation at an optimized speed, in particular at the maximum speed of the pump, and therefore exert the highest possible conveyor effect onto the fluid. In this state of a maximum straightening, the measurements of the interior of the pump housing and of the rotor must be adjusted to each other such that no contact occurs between the two.

It may also be provided that the individual conveyor elements are deformed beyond the state of maximum radial straightening by means of the fluid counter pressure such that they are again compressed radially by the fluid pressure for a distance.

A flow control element, in particular a valve, is advantageously also disposed in the pump housing at an axial distance to the rotor, in particular in the pump interior, in which the rotor is located, which prevents the backflow of the conveyed fluid also during the idle operation of the rotor. The flow control element controls the flow passing the rotor, i.e. for example, the flow through the annular space between a rotor hub and the interior wall of the pump housing.

The control element/valve is located outside of the hub, for example, also at an axial distance to the rotor hub. It comprises, for example, one or more pivotable baffles, which may be moved by the flow itself, in that they are opened by the flow with a flow in the conveying direction, and are automatically closed by the backflow with a flow opposite of the conveyor direction. The baffles themselves may be elastically deformable, and the flow control unit, as well as the rotor, may be radially compressed and expanded.

If a plurality of individual conveyor elements is provided along a hub, they may advantageously be disposed and aligned such that they form the contour of a helical conveyor vane altogether. The individual conveyor elements may then be folded in at the hub, and may be expanded.

The rotor, in particular the hub, however, advantageously both the hub and the conveyor elements, advantageously consists of a foamed polyurethane, a thermoplastic elastomer, a rubber, or a super-elastic material, in particular a super-elastic polymer.

In addition to a pump housing and a blood pump having such a pump housing and a rotor, the invention also relates to a blood pump unit with a pump housing, a rotor, and a catheter connected to the pump housing at one end thereof. The catheter may, for example, be part of a manipulating unit, which allows to at least partially insert the pump housing and the rotor through a blood vessel of a patient into a heart chamber.

In particular, the catheter has a lumen, which is continuous in longitudinal direction, in which a drive shaft for the rotor of the pump is disposed. However, a motor may also be disposed in direct proximity to the pump housing for driving the rotor.

The catheter may also advantageously be directly connected to the pump housing, wherein radial openings for the fluid to be transported may be provided either at the end of the pump housing, and/or at the beginning, or in the extension of the catheter. The catheter advantageously has a substantially small diameter than the interior of the pump housing, and is attached at the end of the pump housing. Advantageously, it is coaxially and concentrically connected to the pump housing. The connection may be carried out, for example, by means of the reinforcement elements of the pump housing, which axially project beyond the pump housing, and may be concentrically bent off radially toward the inside in order to be connected to the catheter at that location. In this manner the extensions of the reinforcement elements/bracers of the pump housing may retain and center the catheter.

