WO2020190141A1

WO2020190141A1 - Artificial sphincter

Info

Publication number: WO2020190141A1
Application number: PCT/NL2020/050188
Authority: WO
Inventors: Katherine Christa MACKENZIE
Original assignee: Erasmus University Medical Center Rotterdam
Priority date: 2019-03-20
Filing date: 2020-03-20
Publication date: 2020-09-24
Also published as: NL2022777B1

Abstract

A human body is provided with a plurality of sphincters f a circular muscle for constricting and/or opening a body lumen around which it is provided. An implantable device as an artificial sphincter may be required when the naturally present sphincter is not functioning as desired. The implantable device may be provided with a lumen mechanism and an engagement section which are arranged for interfacing with the body lumen such that constriction and/or opening forces may be coupled between the body lumen and the implantable device. In a preferred embodiment, the lumen mechanism is arranged as a foldable planar linkage, of which a radial expansion and/or contraction is directly coupled to a distance and/or angle between different joints and/or links comprised by the linkage. By providing an actuator and/or sensor between different links and/or joints of the linkage, a sphincter-like coupling may be obtained between the device and the body lumen.

Description

Title: Artificial sphincter

FIELD OF THE INVENTION

The invention relates to an artificial sphincter.

BACKGROUND

Hirschsprung disease is an enteric neuropathological disease, which affects the nervous system of the gastrointestinal tract, the enteric nervous system (ENS). The ENS normally regulates the peristaltic movement of, and defecation of faeces from, the gastrointestinal tract, and is not present in the distal portion of the colon in a patient with Hirschsprung disease. This results in a portion of colon that is constricted and surgical intervention is required to correct the defect. However, although this surgery removes most of the constricted portion of gut, the anal sphincters of the patient remain without innervation.

Patients that have these defective sphincters experience incontinence problems with some requiring frequent enemas, the

implantation of a stoma and/or requiring the use of diapers in the years post-surgery.

US5593444A discloses a liquid-pumped anal sphincter that works on the basis of a liquid-filled ring that is surgically fitted around the outside of the distal colon and can be manually pumped-up to close the rectum or let out to allow the rectum to release on its own. A stoma is an alternative to cope with issues with anal incontinence.

SUMMARY

Known artificial sphincter devices are provided around the sphincter, and are only arranged for forcefully closing the sphincter. Passive opening is not possible due to automatically contracted muscle that is not able to release due to lack of enteric neural signals. Drawbacks of a stoma are that is an easily detectible or visible device and it requires manual cleaning or emptying.

It is preferred to provide an improved artificial sphincter.

A first aspect provides an implantable device for engaging with a body lumen, comprising a flexible housing comprising a housing lumen arranged to be radially expanded and contracted between an opened and a closed position, a lumen mechanism provided in the housing, comprising a mechanism lumen which is substantially aligned with the housing lumen and arranged to be radially expanded and contracted between an opened position, corresponding to the opened position of the housing, and a closed position corresponding to the closed position of the housing, and an engagement section for engaging with the body lumen, for providing a coupling between radial expansion and contraction activity of the body lumen and the implantable device.

A lumen is defined as a passage for a fluid and/or solid, which may be water, blood, faeces, urine, any other bodily fluid, solid, emulsion, suspension, mixture, any other bodily solid, or any combination thereof. A lumen has a certain flow-through area for the passage, which may be increased or decreased. A lumen may thus be regarded as a cross-section of an elongated, e.g. tube-like, organ arranged for transporting a fluid and/or solid there through.

In a human body, a body lumen may be surrounded by a sphincter muscle. Sphincter muscles may be voluntary or involuntary controllable; i.e. actively and consciously controllable by a human or animal or not.

Voluntary sphincter muscles may be used to control a flow-through area of a body lumen, whilst involuntary sphincter muscles may be used as sensors to sense whether a body lumen is open, closed, or somewhere in between. An implantable device according to the first aspect may thus be employed as an artificial sphincter muscle, seeing as it may deliver similar properties as a sphincter muscle. Examples of sphincter muscles for which the implantable device as an artificial sphincter may be used are the internal anal sphincter, external anal sphincter, ileocecal sphincter, pyloric sphincter, oesophageal sphincters and the urethral sphincter.

With engaging with a body lumen, it is implied that forces may be exchanged between the engagement section and the body lumen, in two directions. Hence, forces from the body lumen may open and close the implantable device via the engagement section, and forces from the implantable device may open and close the body lumen via the engagement section. As such, the mechanism lumen and the body lumen may open and close simultaneously.

The housing lumen provides a passage through the housing, wherein said passage has a certain flow-through area. With the radial expansion of the housing lumen, this flow through area increases, and with the radial contraction, the flow-through area decreases. The flow-through area may, in a contracted state, be substantially zero, thus substantially blocking any flow through the housing lumen.

The housing may comprise materials which are compatible to be inserted into a human body, such as titanium, collagen, biocompatible polymer, other compatible materials, or any combination thereof.

The housing may be substantially doughnut- shaped, i.e. the housing comprises a non-zero inner radius defining the housing lumen as an inner boundary, and an outer radius defining an outer boundary, wherein the outer radius is larger than the inner radius.

The lumen mechanism is provided inside the housing, and as such at least partially defines the shape of the housing. The housing is provided at least substantially around the lumen mechanism, and may as such provide a barrier between the lumen mechanism and its moving parts, and the body in which the device is implanted. Because the engagement section is arranged to provide a coupling between both radial contraction and expansion activity, not only can the body lumen be forcefully closed, but can also be forcefully opened.

The radial expansion and contraction activity of the body lumen and the implantable device may comprise a radial expansion of the body lumen, which by virtue of the coupling provided by the engagement section, may result in a radial expansion of the implantable device, and more in particular the lumen mechanism. Similarly, the radial expansion and contraction activity of the body lumen and the implantable device may comprise a radial contraction of the body lumen which by virtue of the coupling, provided by the engagement section, may result in a radial contraction of the implantable device.

The radial expansion and contraction activity of the body lumen and the implantable device may comprise a radial expansion of the implantable device, and more in particular the lumen mechanism, which by virtue of the coupling, provided by the engagement section, may result in a radial expansion of the body lumen. Similarly, may the radial expansion and contraction activity of the body lumen and the implantable device comprise a radial contraction of the implantable device, and more in particular the lumen mechanism, which by virtue of the coupling, provided by the engagement section, may result in a radial contraction of the body lumen.

The lumen mechanism may comprise a foldable planar linkage comprising a plurality of links connected by a plurality of joints, wherein the linkage encloses an internal area substantially corresponding to the mechanism lumen and wherein the linkage is foldable between a folded position and an unfolded position, wherein in the folded position the internal area enclosed by the linkage is smaller than in the unfolded position. Typically, such a linkage is over constrained. A degree of freedom may however be obtained by choosing appropriate link lengths. The surface area of the inner area may be controlled by folding and unfolding the linkage, wherein folding the linkage decreases the inner area and unfolding the linkage increases the inner area. With the inner area decreasing, a radial distance between two joints which substantially lie on the same radially extending line increases. Furthermore, with the inner area decreasing, a tangential distance between two other joints which are provided substantially equiradially relative to a centre point of the linkage decreases. The joints are preferably joint being arranged to swivel over one axis. However, joint having more degrees of freedom may be envisaged as well.

This relationship between the surface area of the inner area and distances between different joints may be used both for forcefully opening and closing a sphincter, as well as detecting a pressure in the sphincter. In the first case of opening and closing the sphincter, one or more actuators may be provided to control one or more distances between joints for controlling the inner area of the linkage when the linkage is provided around the sphincter. In the latter case of detecting a pressure in the sphincter, when the linkage is provided around the sphincter, the sphincter will exert a pressure to the inner joints of the linkage, which may be measured by measuring a force between different joints of the linkage.

As such, the use of a foldable planar linkages in an artificial sphincter with an actuator and/or a sensor may be regarded as a single innovative concept, using the relationship between the inner area delimited by the linkage and the distance between different joints. Since this distance may be measured and/or controlled, it is possible to control and/or measure the inner area of the linkage, as well as to measure a force or pressure exerted on the inner area of the linkage.

An example of a foldable planar linkage is a Hoberman mechanism, which is a one degree-of-freedom (DOF) mechanism comprising a plurality of linkages. The specific hinging connections of the linkages, and their lengths, allow a coupling between a circumferential motion and a radial motion. Hoberman mechanisms have been used for example in the space industry and in toys. Use of other foldable planar linkages with any number of links and any number of joints is also envisioned.

A foldable planar linkage is often substantially axisymmetric, in folded and unfolded state. As a result thereof, a substantially equal radial force may be obtained across the entire circumference of the linkage which may prevent pressure points on the body lumen.

In general, a foldable planar linkage may be defined as a mechanism comprising a plurality of interconnected links, which links are preferably hingedly interconnected. By virtue of the hinging interconnection of the links, the foldable planar linkage can be manipulated between a folded state and an unfolded state. Multiple links, for example two or more links, which are hingedly interconnected may form scissor-like mechanisms, especially when the joint which interconnects the links is provided near a middle or at least away from an end of at least one of the interconnected links. In particular embodiments, links comprised by the foldable planar linkage may be substantially straight links, for example struts. Preferably, all the links of the foldable planar linkage are substantially straight links,

For example, foldable planar linkages are defined and discussed in A kinematic theory for radially foldable planar linkages by J. Patel, G.K. Ananthasuresh, published in the International Journal of Solids and

Structures 44 (2007) 6279-6298.

Foldable planar linkages may also be known as foldable motion structures, which are for example discussed in Planar mobility modes of 8- bar-jointed structures with a single degree of freedom, by H. Tanaka et al., published in the International Journal of Solids and Structures 49 (2012) 1712-1722.

The radial expansion of a foldable planar linkage may be such that a movement of the joints that are closest to a centre of the linkage is substantially only radial during expansion and contraction of the foldable planar linkage. Other joints may exhibit movements in a radial and/or a tangential direction.

The plurality of links of a foldable planar linkage being connected by a plurality of joints may imply that each link is at each of its two ends directly connected to a further link by means of a joint. By virtue of the joint, the interconnected links can hinge relative to each other over that joint.

A foldable planar linkage being planar implies that preferably all the links and joints of the foldable planar linkage are contained within a substantially flat volume. The thickness of such a flat volume may for example correspond to the thickness of one link, of two links, of two links and one joint, or of one joint. In further examples, the thickness of the foldable planar linkage is a number of times smaller than an outer radius of the foldable planar linkage in unfolded shape, which number may be for example two, four, eight, ten, fifteen or even more.

When the implantable device is to be used for at least partially controlling the flow-through area of a body lumen, the device may comprise of an actuator for manipulating the lumen mechanism such that the mechanism lumen can be positioned between a closed position and an opened position, wherein the engagement section is arranged to transfer contraction and expansion forces from the actuator to the body lumen to which the implantable device is engaged. As such, the implantable device may be employed as an artificial voluntary sphincter. As the mechanism is to be provided around tissue or within tissue defining the body lumen, the closed position of the lumen mechanism and the closed position of the housing do not necessarily define positions in which there is no central passage defined in the centre of the lumen mechanism and/or the housing. Rather, in the opened position, this passage has an area larger than in the closed position. The actuator may comprise two ends, and the actuator may be arranged to manipulate an actuator distance between the two ends. Next, the actuator may at a first end be connected to a first joint, which first joint connects a first link and a second link, at a second end connected to a second joint, which second joint connects a third link and a fourth link, wherein manipulation of the actuator distance folds the planar linkage between the folded position and the unfolded position.

Next to a relation between a distance between two joints, there is also a relation between an angle between two adjacent links and the flow through area of the mechanism lumen. As such, an angular actuator may be provided connecting two adjacent links, and arranged to manipulate the angle between the two adjacent links.

Next to or instead of being used as an actuating device, embodiments of the implantable device may comprise a sensor for

determining lumen data of the mechanism lumen, wherein the engagement section is arranged to transfer contraction and expansion forces from the body lumen to which the implantable device is engaged to the sensor. As such, the implantable device may be employed as an artificial involuntary sphincter.

Lumen data of the mechanism lumen may comprise data on a flow-through area through the mechanism lumen at a certain point in time. Such data may relate to an absolute value, e.g. a diameter measured in millimetres or an area measured in millimetres squared. Such data may alternatively or additionally relate to a relative value relating to a state of the mechanism lumen, e.g. closed, fully opened, or partially opened.

Lumen data of the mechanism lumen may further comprise, as an option or additionally to the data on the flow through area, data on a pressure exerted on the lumen mechanism. Such a pressure may be caused by material passing through the body lumen which cause the body lumen to expand radially. E.g. faeces passing through part of a colon as a body lumen may cause the colon to expand radially by exerting a pressure on the colon. Pressure may also be exerted on the lumen mechanism by a sphincter muscle or artificial sphincter provided adjacent to it.

The sensor for determining lumen data of the mechanism lumen may comprise two ends. The sensor may be arranged to obtain data on a distance and/or pressure between the two ends, and the sensor may be at a first end connected to a first joint, which first joint connects a first link and a second link, at a second end connected to a second joint, which second joint connects a third link and a fourth link.

When the lumen mechanism is arranged as a planar linkage mechanism, this sensor may determine lumen data based on the measured distance and/or pressure between the two ends.

The sensor for determining lumen data of the mechanism lumen may be connected to a first link and a second link provided adjacent to the first link. In such a case, the sensor may be arranged to obtain data on an angle and/or force between the first link and the second link.

It will be appreciated that neither an actuator nor a sensor is necessary for all embodiments of the implantable device. For example, an implantable device without an actuator may be manipulated by hand, for example by a surgeon or a person in whose body the implantable device is implanted and/or by an external actuator not comprised by the implantable device. One or more stiffness, biasing and/or locking elements may be comprised by the implantable device to prevent and/or limit folding and/or unfolding of the lumen mechanism without manipulation by a person. An implantable device without a sensor may be manipulated by a person or by another actuator based on inputs other than those which have to be obtained using a sensor. A person manipulating the lumen mechanism of an implantable device may hence also be regarded as an actuator, in particular as an external actuator not comprised by the implantable device. When the lumen mechanism is arranged as a planar linkage mechanism, a first subset of joints may be provided on a first radius from a centre point of the linkage, a second subset of joints may be provided on a second radius from the centre point of the linkage, and a third subset of joints may be provided on a third radius from the centre point of the linkage, and wherein the links may be provided between joints from the first subset and the second subset, and between the second subset and the third subset.

The implantable device may be provided with an input module for receiving a control signal, and a control module for operating the actuator in accordance with the control signal. The control signal may comprise data on a preferred state for the implantable device. Such a preferred state may relate to the state of the mechanism lumen, e.g. open or closed, or to a particular flow through area for the mechanism lumen. The control signal may be provided by a user, a sensor, or both.

The sensor may be arranged to output an output signal comprising distance/pressure data. The output signal may be provided to a user, e.g. to a portable user device with a graphical interface. As such, the user may be made aware of a state of the sensor, and thus a state of the implantable device.

A second aspect provides a kit of parts comprising a first implantable device according to any of the embodiments in which the first implantable device comprises an actuator for manipulating the lumen mechanism and a second implantable device in which the second

implantable device comprises a sensor for determining lumen data on the mechanism lumen of the second implantable device. As such, a situation comparable to the human anatomy, in which the colon is provided with a first, involuntary, sphincter muscle and a second, voluntary, sphincter muscle may be approximated. A third aspect provides a method for opening and closing an implantable device, comprising a user control device, receiving

distance/pressure data from a distance/pressure sensor comprised by a first implantable device, by the user control device, outputting a user signal related to the received distance/pressure data, by the user control device, receiving a user input signal comprising actuation data, by the user control device, sending an actuation signal comprising actuation data to a second implantable device comprising a lumen mechanism actuator, and actuating the lumen mechanism actuator according to the received actuation data.

In particular, the method according to the third aspect may be a method for opening and closing a device already implanted in a human or animal and/or a method for opening and closing a device which has previously been implanted in a human or animal.

A fourth aspect provides another method for opening and closing an implantable device, comprising detecting, with a sensor provided by the implantable device, a change in body lumen opening state of a body lumen around which the implantable device is provided, and manipulating, with an actuator provided by the implantable device, a mechanism lumen in accordance with the change in body lumen opening state. With such a method, a sphincter muscle may be assisted in its operation.

In particular, the method according to the fourth aspect may be a method for opening and closing a device already implanted in a human or animal and/or a method for opening and closing a device which has previously been implanted in a human or animal.

BRIEF DESCRIPTION OF THE FIGURES

The various aspects and embodiments thereof will now be discussed in conjunction with drawings. In the drawings: Fig. 1A: shows a schematic view of an implantable device provided around a body lumen;

Fig. IB and Fig. 1C: show the implantable device in a side view around the body lumen;

Fig. 2: shows a schematic view of another embodiment of the implantable device provided around a body lumen;

Fig. 3A and Fig. 3B: show yet another embodiment of the implantable device;

Fig. 4A and Fig. 4B: show part of a planar linkage mechanism as a lumen mechanism of an implantable device; and

Figure 5: shows a sheath as an embodiment of a housing for the implantable device.

DETAILED DESCRIPTION OF THE FIGURES

Fig. 1A shows a schematic view of a body with a rectum 102 as a body lumen in a cross-sectional view. Provided around the rectum 102 is an implantable device 100 for engaging with a body lumen, comprising a housing 104 with a housing lumen 106. Provided in the housing 104 is a lumen mechanism 108 with a mechanism lumen 110.

The mechanism lumen 110 may define a passage there through for a fluid and/or solid. As such, the mechanism lumen 110 may have a certain flow through area for the passage, which may be increased or decreased by respectively expanding or contracting the mechanism lumen 110.

Figs. IB and 1C show the implantable device 100 in a side view, wherein in Fig. IB the device 100 is in an expanded state and in Fig. 1C the device 100 is in a contracted state, wherein the housing lumen 106 and mechanism lumen 110 are smaller than their respective counterparts in Fig. IB. When provided with an actuator, the implantable device 100 may provide a force to the rectum 102 such that the rectum 102 deforms from the expanded state of Fig. 1C into the contracted state of Fig. IB. Alternatively or additionally, the actuator of the implantable device 100 may provide a force to the rectum 102 such that the rectum 102 deforms from the contracted state of Fig. IB to the expanded state of Fig. 1C.

For exchanging forces between the body lumen 102 and the implantable device 100, the implantable device 100 comprises an

engagement section. Through this engagement section, radial expansion and contraction force may be transferred between the body lumen and the implantable device.

Examples of possible engagement sections are, when the housing 104 is at the housing lumen 106 connected to the body lumen 102, the part of the housing 104 connected to the body lumen 102. Such a connection may be constituted by a glue, stitching, by allowing the body to grow tissue between the implantable device 100 and the body lumen 102, by implanting the device 100 in a sphincter muscle or the surrounding fat, or any other method of connecting the implantable device 100 to the body lumen. The engagement section thus is not necessarily a separate part of the

implantable device 100, but may be formed by one of the other parts of the implantable device 100.

Fig. 2 shows a schematic view of a body with the rectum 102 as the body lumen in a front view. Implanted in the body is an implantable device combination 200 of a first implantable device 210 at a first location

201 and a second implantable device 220 at a second location 202, both implantable devices comprising a housing 104 with provided therein a lumen mechanism 108. In the implementation of Fig. 2, the second location

202 is downstream of the first location.

A human rectum is provided with an internal sphincter and an external sphincter, of which the first one is an involuntary sensor-like sphincter, and the latter one is a voluntary actuator-like sphincter. The combination of the two implantable devices may be used to mimic the workings of the two rectal sphincters.

The first implantable device 210 may be provided with a sensor 205 for determining lumen data on the mechanism lumen 110. As such, it may detect the open state of the body lumen at a first location 201 due to faeces 203 passing through the body lumen.

Upon such a detection, the sensor 205 may send a signal to a user device 206. In response to receiving the signal, the user device 206 may provide an alert to the user making him aware of the open state of the body lumen at the first location 201.

A user device 206 may for example be a smartphone, pager, or dedicated portable device, and the device 206 may comprise signalling means using for example an audible and/or visual signal for alerting the user.

The second implantable device 220 is provided with an actuator 208, arranged to manipulate the mechanism lumen of the lumen mechanism 108. In the schematic Fig. 2, the second device 220 has contracted the rectum at the second location 202 by virtue of the actuator 208.

The actuator 208 may be provided with an input module for receiving a control signal, e.g. from the user device 206. Such a control signal may be used by a control module to operate the actuator 208 in accordance with the control signal. The user may, via the user device 206, provide a

With the combination of the first implantable device 210, the second implantable device 220 and the user device 206, it becomes possible to allow a user to know when there is a need to empty his bowel, and to control when this should happen.

In an alternative embodiment, contrary to what is shown in Fig.

2, an implantable device may be provided with a single housing and a single lumen mechanism, and this lumen mechanism may be provided both with an actuator and a sensor. As such, it may be possible to first detect a state of the body lumen with the sensor, and operate the actuator in response to the detected state.

For example, when the sensor detects that the body lumen is moving from a contracted state to an expanded state, the actuator may assist in opening the body lumen by opening the mechanism lumen.

Fig. 3 A shows an embodiment of the implantable device, wherein the lumen mechanism 108 comprises a foldable planar linkage 300 comprising a plurality of links connected by a plurality of joints. The linkage 300 encloses an internal area substantially corresponding to the mechanism lumen 110, indicated as the dashed circle. The linkage 300 is foldable between an unfolded position, as shown in Fig. 3 A, and a folded position, as shown in Fig. 3B. The internal area enclosed by the planar linkage 300 is in the folded position of Fig. 3B smaller than in the unfolded position of Fig.

3A, and may be substantially zero in the folded position Fig. 3B such that substantially no passage of fluid, solid, and/or gas is possible through the body lumen 102.

Fig. 4A shows part of a planar linkage mechanism 300 as a lumen mechanism with a mechanism lumen 110 for an implantable device, and will be used to elaborate on some envisioned locations and manner of operation for actuators and/or sensors. Of the planar linkage mechanism 300, a first sub-mechanism 301, a second sub-mechanism 302, and a third sub-mechanism 303 are shown. Each sub-mechanism comprises four joints and four links, wherein the links are at ends connected to adjacent links with a joint. The three sub-mechanisms define a mechanism lumen 110 with a particular radius R.

A sub-mechanism may alternatively be defined in another way, for example with the two components of the second sub -mechanism 302 connected to the third sub-mechanism 303 and the two components of the third sub-mechanism 303 connected to the second sub-mechanism 302.

Now looking at the first sub-mechanism 301, as a dotted line a first location PI for a sensor and/or actuator is shown. In this orientation, the sensor and/or actuator is oriented substantially tangentially relative to the lumen perimeter, and spans between two joints referenced to as J1 and J2. Since the planar linkage mechanism 300 only has a single degree of freedom due to the specifically chosen link lengths and/or other parameters, there is a direct relation between the distance between J1 and J2 and the radius R of the mechanism lumen 110.

If an actuator is provided at the first location PI, such an actuator may be used to control a distance between joints J1 and J2. For example, the distance between J1 and J2 may be decreased to obtain the situation as sketched in Fig. 4B. Here, the radius R’ of the mechanism lumen 110 has decreased by virtue of the decrease in distance between J1 and J2. As such, an actuator controlling the distance between joints J1 and J2 at the first location PI may be used to control the flow through area through the mechanism lumen 110.

Next to being a possible location for an actuator, at the first location PI also a sensor may be provided, wherein the sensor may be connected to joints J1 and J2. Connected in such a way, the sensor may be used to determine a distance and/or a force between the joints J1 and J2. Such a distance may be used to determine a state of opening of the lumen mechanism, and when engaged with the body lumen, a state of opening of the body lumen. Such a force may be used to determine a radial pressure on the lumen mechanism, a pressure which may originate from a pressure exerted by the body lumen on the engagement section of the implantable device.

Now referring back to Fig. 4A, a second location P2 is shown at the second sub-mechanism 302 indicating a second option for a location for a sensor and/or actuator. A sensor and/or actuator provided at the second location P2 may be spanned between two joints J3 and J4, in an orientation substantially radially relative to the mechanism lumen 110. The distance between J3 and J4 is directly related to radius R of the mechanism lumen 110, a relationship which may be used for controlling the radius R with an actuator or determining the radius R with a sensor.

If an actuator is used to increase the distance between joints J3 and J4 relative to the distance shown in Fig. 4 A, a situation as sketched out in Fig. 4B may be obtained, wherein the radius R’ has decrease relative to the radius R by virtue of the increase in distance between joints J3 and J4.

Similar to the first location PI, at the second location P2 a sensor may be provided. Now between joints J3 and J4, a sensor may be provided for measuring a distance and/or force between joints J3 and J4.

Again referring back to Fig. 4A, a third location P3 is indicated by a dotted line as a location where a sensor and/or an actuator may be provided. The dotted line P3 refers to the angle between links LI and L2, which are provided at a certain angle relative to one another. The angle between links LI and L2 is directly related to the radius R of the

mechanism lumen 110, and this relationship may thus be used for a sensor and/or an actuator.

If an actuator is provided at the third location P3, the angle between links LI and L2 may become controllable, and with that the radius R may become controllable. If the actuator would enlarge the angle between links LI and L2, a situation as sketched out in Fig. 4B may be obtained, wherein the radius R has shrunk to radius R’ due to the increase in angle between links LI and L2. At the third location P3, also a sensor may be employed for determining data on an angle and/or torque between links LI and L2.

While figures 4A and 4B have been used to show some example locations for actuators and/or sensors, any other location is also envisioned where a actuator or sensor may be placed to control and/or detect radius R of the mechanism lumen 110.

The embodiment of the planar linkage mechanism 300 as shown in Figs. 4A and 4B comprises an intermittent pattern of a sub-mechanism with large links, such as sub-mechanisms 301, 302, 303, and sub

mechanisms with short links. Although the locations PI, P2, P3 in Figures 4A and 4B are positioned in the sub -mechanisms with large links, these positions may also be provided in the sub-mechanisms with the short links.

When a distance is to be controlled, any type of actuator may be used arranged to manipulate a distance, such as linear actuators, which may be magnetically-driven, piston rod actuators, spindle drives, any other type of actuator or any combination thereof.

When an angle is to be controlled, the same types of actuators as described above may be used. Alternatively, a rotational actuator may be used for manipulating the angle between two adjacent links which are connected by the same joint.

For implanting an implantable device according to any of the embodiments as described herein, a method may be used wherein the implantable device is first manipulated into an opened state, wherein, instead of the housing comprising a housing lumen and the lumen mechanism comprising a mechanism lumen, both the housing and the lumen mechanism are opened up to form an opened, for example C-like, shape. As such, the implantable device may be more easily provided around the body lumen.

Once the device is implanted, the ends of the C- shape are connected to surround the body lumen. Several options are available for providing this connection. In one option, the ends of the C-shape of the housing are closed and connected. This means that ends of the lumen mechanism are not connected. In such implementation, the lumen mechanism is provided to maintain its C-shape even with the ends of the C- not connected. In another implementation, the ends of the C-shape of the housing are connected such that a toroid shape volume is provided

(popularly known as a doughnut shaped volume). In this volume, the ends of the C- shaped lumen mechanism may be connected forming an O- shape, or not.

When provided around the body lumen, the housing and the lumen mechanism may be closed up to respectively form the housing lumen and the mechanism lumen. For example, when the lumen mechanism comprises the foldable planar linkage, one or more links may be

disconnected at one or more joints such that the linkage may be provided around the body lumen. When the implantable device is then provided around the body lumen, the disconnected links may be reconnected to form the mechanism lumen and the housing may be closed up again to form the housing lumen.

For creating an appropriate space around the body lumen to position the implantable device in, it may be required to make space in the tissue surrounding the body lumen. For example may a hooked needle be used for opening up tissue, such as fat tissue of muscle tissue, surrounding the body lumen.

After the implantable device has been implanted, i.e. it has been provided around the body lumen, tissue may grow back around the implantable device. With this grown back tissue, a force coupling may be established between the implantable device and the body lumen such that radial expansion and contraction forces may be coupled between the body lumen and the implantable device. Parts of the implantable device, such as the housing, may comprise materials which promote growth of body tissue on these parts of the implantable device which comprise such a material.

Fig. 5 shows a sheath 500 comprising a woven tube 502, which tube 502 defines an inner space 503 with a certain diameter 504. The tube 502 has a substantially cylindrical shape, and the inner space 503 is sufficiently large for accommodating one or more implantable devices. The tube 502 is woven such that it provides a certain degree of flexibility to allow it to be contracted— i.e. the diameter 504 decreases— and/or extended — i.e. the diameter 504 increases. A force required for the extension and/or contraction may be provided by an implantable device as discussed above.

The sheath 500 comprises a biocompatible material, and may as such be implanted in a human body together with the implantable device. The material comprised by the sheath 500, and the shape of the woven tube 502 may be chosen such to stimulate tissue growth on the sheath 500.

The sheath 500 may be implanted around the implantable device and/or surrounding tissue, such that tissue may heal around the sheath 500. When tissue has grown around the sheath 500, and the implantable device has been provided within the inner space 503 of the sheath 500, the implantable device is enclosed in tissue and as such the enclosing tissue may be contracted and/or extended along with the device.

The sheath 500 may be provided around the lumen mechanism 108 in various ways. In one implementation, the sheath 500 is provided in the mechanism lumen 110 and subsequently, the distal end and end of the sheath are folded around the lumen mechanism such that both ends meet at an outer side of the lumen mechanism 108. Alternatively, the lumen mechanism is provided in the sheath 500 and the distal end and the proximal end of the sheath 500 are connected inside the mechanism lumen 110. In yet another implementation, the sheath 500 is shaped as a toroid, with the lumen mechanism inserted in the inner space and the proximal end the distal end of the sheath 500 connected - with the diameter 504

remaining substantially the same from the distal end to the proximal end.

Claims

1. An implantable device for engaging with a body lumen, comprising:

a flexible housing comprising a housing lumen arranged to be radially expanded and contracted between an opened and a closed position;

a lumen mechanism provided in the housing, comprising a mechanism lumen which is substantially aligned with the housing lumen and arranged to be radially expanded and contracted between an opened position corresponding to the opened position of the housing and a closed position corresponding to the closed position of the housing; and

an engagement section for engaging with the body lumen for providing a coupling between radial expansion and contraction activity of the body lumen and the implantable device.

2. Implantable device according to claim 1, wherein the lumen mechanism comprises a foldable planar linkage comprising a plurality of links connected by a plurality of joints, wherein the linkage encloses an internal area substantially corresponding to the mechanism lumen and wherein the linkage is foldable between a folded position and an unfolded position, wherein in the folded position the internal area enclosed by the linkage is smaller than in the unfolded position.

3. Implantable device according to claim 1 or 2, further comprising:

an actuator for manipulating the lumen mechanism such that the mechanism lumen can be positioned between the closed position and the opened position, wherein the engagement section is arranged to transfer contraction and expansion forces from the actuator to the body lumen to which the implantable device is arranged to be engaged.

4. Implantable device according to claim 3, wherein the actuator comprises two ends, the actuator is arranged to manipulate an actuator distance between the two ends, and the actuator is:

at a first end connected to a first joint, which first joint connects a first link and a second link;

at a second end connected to a second joint, which second joint connects a third link and a fourth link;

wherein manipulation of the actuator distance folds the planar linkage between the folded position and the unfolded position.

5. Implantable device according to claim 3, wherein the actuator is connected to a first link and a second link, wherein the first link is provided adjacent to the second link and the actuator is arranged for manipulating an angle between the first link and the second link.

6. Implantable device according to any of claims 3-5, further comprising an input module for receiving a control signal, and a control module for operating the actuator in accordance with the control signal.

7. Implantable device according to any of the preceding claims, further comprising:

a sensor for determining lumen data on the mechanism lumen, wherein the engagement section is arranged to transfer contraction and expansion forces from the body lumen to which the implantable device is engaged to the sensor.

8. Implantable device according to claim 7, to the extent dependent on claim 2, wherein the sensor comprises two ends, the sensor is arranged to obtain data on a distance and/or a pressure between the two ends as lumen data, and the sensor is: at a first end connected to a fifth joint, which fifth joint connects a fifth link and a sixth link;

at a second end connected to a sixth joint, which sixth joint connects a seventh link and an eighth link.

9. Implantable device according to claim 7, to the extent dependent on claim 2, wherein the sensor is connected to a first link and a second link, wherein the first link is provided adjacent to the second link and the sensor is arranged to obtain data on an angle and/or a force between the first link and the second link.

10. Implantable device according to any of the claims 7-9, wherein the sensor is arranged to output an output signal comprising distance/pressure data.

11. Kit of parts, comprising:

a first implantable device according to any of the claims 3-6; and a second implantable device according to any of the claims 7-10.

12. Method for opening and closing an implantable device, comprising:

by a user control device, receiving distance/pressure data from a distance/pressure sensor comprised by a first implantable device;

by the user control device, outputting a user signal related to the received distance/pressure data;

by the user control device, receiving a user input signal comprising actuation data;

by the user control device, sending an actuation signal comprising actuation data to a second implantable device comprising a lumen

mechanism actuator; and actuating the lumen mechanism actuator according to the received actuation data.

13. Method for opening and closing an implantable device, comprising: - detecting, with a sensor provided by the implantable device, a change in body lumen opening state of a body lumen around which the implantable device is provided; and

manipulating, with an actuator provided by the implantable device, a mechanism lumen in accordance with the change in body lumen opening state.