The invention relates to an arteriovenous graft system, comprising an arteriovenous graft provided with a valve device, wherein the valve device has an open state, in which fluid flow through the graft is possible and a closed state, in which the fluid flow through the arteriovenous graft is blocked, wherein the graft system comprises an actuator device to actuate the valve device between the closed state and the open state, and wherein a transmission cable connects the actuator device with the valve device.

Such an arteriovenous graft system is particularly applied in hemodialysis patients. Hemodialysis is the process to filter a patient' s blood and remove toxins with the aid of an extracorporeal dialysis machine. One end of the artificial graft is connected to an artery while the other end is connected to a vein, and the graft is typically placed either in the leg or arm of a patient. The artificial arteriovenous graft is used as a shunt to avoid complications with hemodialysis patients that require peripheral vascular access, as the complication rate is extremely high due to the constantly elevated and turbulent flow over the shunt .

W02020/055247 discloses such an arteriovenous graft system for subcutaneous placement, wherein the actuator device may be wirelessly controlled externally of the patient to move the valve device between the first position and the second position. This wireless control may for example use an electrical or magnetic field with which the actuator device may be controlled without direct contact. A magnetic field may for example be provided by a permanent magnet .

The teaching of W02020/055247 leaves open how the magnetic field operating on the actuator device may be realized in practice, and fails to disclose how to answer to specific requirements such as how to provide a stable position of the valve device in every position between the open state and the closed state. It is therefore one of the objects of the invention to secure that the valve device can be stably positioned in every position between the open state and the closed state.

It is a further object of the invention to provide a lock to the valve device when it is in the closed position.

Still a further object of the invention is that the valve device will be non-backdrivable .

Yet a further object of the invention is that there will be a high transmission ratio between the actuator device and the valve device.

These and other objects of the invention are achieved with an arteriovenous graft system having features according to one or more of the appended claims.

According to a first aspect of the invention the actuator device comprises at least one movable magnet, which at least one magnet directly or indirectly connects to a rotatable plate which is equipped with a spiralled groove, wherein said spiralled groove receives a pin that is movable in a linear path, wherein said pin is connected to the transmission cable so as to arrange that motion of the at least one magnet translates into a linear displacement of the pin and of the transmission cable connected thereto. With the arteriovenous graft system of the invention the graft can be kept stable in any selected position because the graft is non-backdrivable. Thus, the flow through the graft can be regulated to any desired flow.

Apart from the above objects, over-actuation of the at least one magnet can be prevented by arranging that the at least one magnet is sensitive to excitation by an external magnetic field driving the at least one magnet into a desired motion.

To improve accuracy of motion and sensitivity of the at least one magnet to be placed in motion, it is preferable that the actuator device comprises a ring of magnets that are movable along a circular path.

Preferably the ring of magnets provides an asymmetric magnetic field. Such an arrangement causes that a linkage with an external apparatus providing said external magnetic field is only possible by a predefined positioning of the external apparatus.

In a suitable embodiment the ring of magnets are oriented with neighbouring magnets having alternating north and south poles, except for at least one neighbouring pair of magnets having the same orientation of north and south poles.

Desirably the pin which is connected to the transmission cable is mounted on a follower element that is movable in a linear groove provided in a supporting baseplate of the actuator device .

Reliable maneuvering of the magnets is promoted by arranging that the ring of magnets is kept in a predefined position with respect to each other by placement of the magnets in a magnet holder that is equipped with regularly along a circular path distributed receptacles for the magnets.

Although it is possible that the magnet or magnets directly connect to the rotatable plate which is equipped with the spiralled groove (by direct mounting or through magnetism) , it is preferred to provide this connection indirectly by arranging that the magnet holder is rotationally fixed with respect to the rotatable plate.

Suitably the actuator device, the transmission cable, and the arteriovenous graft provided with the valve device are equipped to be placeable subcutaneously in a human or animal.

Preferably the actuator device is provided with stitching holes to enable stitching the actuator device to subcutaneous tissue so as to prevent migrating of the actuator device.

In still another aspect of the invention which can be applied independent from all the other features disclosed herein, or in combination with any one of such other features, the transmission cable is provided with a loop, wherein said loop is preferably stabilised to prevent its loosening. This loop can be tailored to a desired distance between the valve device and the actuator device. This allows any traction on subcutaneous tissue and vessels to be limited, without interfering with the operation of the arteriovenous graft system. Placing a knot in the loop makes it stable and prevents the loop from coming loose .

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of an arteriovenous graft system according to the invention that is not limiting as to the appended claims.

In the drawing:

- figure 1A shows an arteriovenous graft system of the invention in an isometric view;

- figure IB shows a detail of figure 1A, to note the graft together with the valve device;

- figure 2 shows an exploded view of the actuator device forming part of the arteriovenous graft system of the invention;

- figure 3 shows a preferred magnet configuration of the actuator device forming part of the arteriovenous graft system of the invention; and

- figure 4 shows an arteriovenous graft system of figure 1, wherein the transmission cable is provided with a loop, and said loop is stabilised to prevent its loosening.

Whenever in the figures the same reference numerals are applied these numerals refer to the same parts.

Figure 1A depicts an arteriovenous graft system 1, comprising an arteriovenous graft 2 provided with a valve device 3, wherein the valve device 3 is in an open state, in which fluid flow through the graft 2 is possible. Figure IB shows in detail the arteriovenous graft 2 and the valve device 3 of figure 1A, wherein the valve device 3 and the graft are in a closed state, in which the fluid flow through the arteriovenous graft 2 is blocked .

The placement and operation of the combination of the valve device 3 and the arteriovenous graft 2 as such is prior art and requires no further elucidation to explain the invention. The skilled person may refer to W02020/055247 to understand this background of the invention.

The graft system 1 of the invention as explained hereinafter comprises an actuator device 4 to actuate the valve device 3 between the closed state and the open state, wherein a transmission cable 5 connects the actuator device 4 with the valve device 3.

Turning now for an explanation of the actuator device 4 to figure 2, it shows that the actuator device 4 comprises at least one movable magnet 6. Actually in the shown preferred embodiment the actuator device 4 comprises a ring of magnets 6 that are movable along a circular path. The ring of magnets 6 is preferably kept in a predefined position with respect to each other by placement of the magnets 6 in a magnet holder 9 that is equipped with regularly along a circular path distributed receptacles 10 for the magnets 6.

The at least one magnet or ring of magnets 6 connects to a rotatable plate 7 which is equipped with a spiralled groove 7' (as shown at the underside of the plate 7 visible in the righthand part of this figure 2) . The connection of the ring of magnets 6 to the plate 7 is preferably provided by providing a rotationally fixed mounting of the magnet holder 9 to the plate 7.

With reference to figure 3 it is shown that the ring of magnets 6 provides an asymmetric magnetic field, by arranging that the ring of magnets 6 are oriented with neighbouring magnets having alternating north and south poles, except for at least one neighbouring pair of magnets having the same orientation of north and south poles.

Turning back to figure 2, it is shown that the spiralled groove 7' at the underside of the plate 7 receives a pin 8 that is movable in a linear path. The movability of the pin 8 along the linear path is preferably arranged by mounting the pin 8 on a follower element 8' that is movable in a linear groove 11 provided in a supporting baseplate 12 of the actuator device 4. Said pin 8 is connected to the transmission cable 5 so as to arrange that motion of the at least one magnet or ring of magnets 6 translates into a linear displacement of the pin 8 and likewise a linear displacement of the transmission cable 5 connected thereto .

As already noted above the actuator device 4, the transmission cable 5, and the arteriovenous graft 2 provided with the valve device 3 are equipped to be placeable subcutaneously in a human or animal. In order to operate the arteriovenous graft system 1 of the invention, the magnet or magnets 6 forming part of the actuator device 4 is/are sensitive to excitation by an external magnetic field driving the magnet or magnets 6 into a desired motion so as to actuate the valve device 3 through the intermediate transmission cable 5.

Figure 2 shows that the actuator device is provided with stitching holes 13 to enable stitching the actuator device 4 to subcutaneous tissue.

Figure 4 shows that the transmission cable 5 is provided with a loop, wherein said loop is preferably stabilised to prevent its loosening. The loop can move freely to keep the distance between the valve device 3 and actuator device 4 variable during everyday movements, thus limiting subcutaneous traction.

Embodiments of the present invention can include every combination of features that are disclosed herein independently from each other. Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exemplary embodiment.

Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. Unless specifically stated as being "essential" above, none of the various components or the interrelationship thereof are essential to the operation of the invention. Rather, desirable results can be achieved by substituting various components and/or reconfiguration of their relationships with one another.