Patent Description:
Various surgical techniques, and implants, have been proposed for treating obesity and diabetes. Surgical techniques include creation of gastric pockets and gastric bypasses of the stomach, duodenum and part of the jejunum. Bypass tubes or liners have been proposed for insertion into the gastro-intestinal tract, to bypass the duodenum and optionally part of the jejunum.

Technical challenges remain for many of these techniques. For example, the endoscopic placement and anchoring of bypass tubes remains challenging. One technique proposed is to anchor the tube in the vicinity of the pylorus. However, the stomach and intestine are subject to significant motion in normal bodily function. Muscular contractions of the stomach, including at the pyloric antrum, complicate maintaining the tube in position. The muscular contractions can be extreme in the case of, for example, the patient vomiting. Dislodgement either towards the duodenum, or into the stomach, can necessitate medical intervention to correct the position or to retrieve the bypass tube. Many existing proposals are compromised by the apparently conflicting need for secure anchoring, yet with atraumatic engagement with the body tissue to avoid the device causing tissue irritation.

It would be desirable to address and/or mitigate one or more of the above issues.

Non-limiting embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings, in which:.

In the following description, the same reference numerals are used to denote similar or equivalent features, whether or not described in detail. The description of one embodiment can thus be combined with another embodiment. Where a tube is described, the tube may optionally be a bypass tube or bypass conduit for bypassing a portion of the bowel to reduce nutrient uptake. Referring to <FIG>, a tube <NUM> is illustrated for introduction into at least the duodenum D of a patient, for the treatment of diabetes or obesity. The tube <NUM> optionally may extend to the jejunum. A proximal end 10a of the tube may be disposed in the duodenum D close to the pylorus P as shown in <FIG>, or it may extend at least partly through the pylorus P. The tube <NUM> comprises a cuff or stent <NUM> for resisting displacement from the implanted position towards the stomach. The tube <NUM> may optionally comprise reinforcement (not shown in <FIG>, but reference <NUM> in later figures) for preventing twisting of the tube <NUM> at the pylorus that could create a blockage.

An anchor <NUM> for the tube <NUM> comprises a gastric bulb <NUM> for placement with the stomach S. The gastric bulb <NUM> has a collapsed state suitable for introduction into the stomach, for example, through the patient's mouth, and an operative state in which the bulb <NUM> bulges to define an anchor that resists displacement through the pylorus P.

The anchor <NUM> is coupled, or couplable, to the tube <NUM> by any suitable coupling, for example, by one or struts or one or more flexible tethers <NUM>. Alternatively, the anchor <NUM> is mounted directly on the tube <NUM>.

In the illustrated examples, the bulb <NUM> is configured such that, in the expanded condition a pressure within the bulb is (i) not greater than atmospheric pressure, and/or (ii) not greater than surrounding pressure within the stomach. The bulb <NUM> is not permanently substantially pressurized compared to the surrounding ambient pressure within the stomach. This contrasts with a type of balloon or bulb that is inflated, and distends from within by virtue of inflation pressure.

By virtue of, for example, absence of a positive pressure within the bulb <NUM>, the bulb <NUM> is able to partly collapse in response to stomach contractions. This enables the bulb <NUM> to exhibit, at least partly, compliance with the stomach contractions, and to absorb the contractions without pulling overly on the tube <NUM>, which might otherwise dislodge the tube <NUM> into the stomach. The bulb <NUM> can partly compress to absorb or accommodate extreme transient stomach contractions, for example, should the patient vomit. At the same time, the bulb <NUM> is biased to its operative condition in which is serves to prevent displacement in the distal direction, as the bulb <NUM> will resist passage towards and through the pylorus.

In the illustrated examples, the bulb <NUM> is self-expandable from the collapsed condition to the operative condition. The gastric bulb <NUM> can comprise a self-expandable structure <NUM> (depicted schematically in part in <FIG>), optionally a frame structure (e.g. with ribs and/or struts), and/or a mesh structure.

In one version, the gastric bulb <NUM> may be open to its interior and/or have communication apertures allowing chyme to pass into the interior of the bulb <NUM>. For example, the bulb <NUM> may comprise an open frame <NUM>.

Alternatively, the bulb <NUM> may comprise a fluid-tight chamber. The chamber may have an inlet port <NUM> for allowing fluid to be drawn into the chamber as the gastric bulb <NUM> expands to its operative condition under the influence of the self-expanding property, for example, provided by self-expanding frame <NUM>. A delivery device may include an inflow conduit (e.g. vent channel) removably coupled to the inlet port <NUM> to allow pressure equalization and/or inflation by admission of fluid. The fluid may, for example, be a liquid (e.g. saline) or a gas (e.g. air). After pressure equalization and/or inflation is complete, the inflow conduit can be disconnected from the inlet port <NUM>, thus sealing the chamber. The small quantity of fluid in the chamber can provide a compliant cushion that supplements the self-expanding frame <NUM>, providing an atraumatic anchor with compliant characteristics. Optionally, the fluid-tight chamber may include a central passage (not shown) for allowing chyme to pass towards the pylorus and the entrance to the tube <NUM>.

Where both a self-expanding structure and a fluid-tight chamber are provided, the self-expanding structure and the fluid-tight chamber may be nest one at least partly (optionally substantially entirely) within the other. For example, the fluid-tight chamber may be nested at least partly (optionally substantially entirely) with the self-expanding structure. A surface (e.g. outer surface) of the fluid-tight chamber may be in surface-to-surface contact (e.g. laminated) with a surface (e.g. inner surface) of the self-expanding structure.

With or without self-expansion, the bulb may comprise a fluid-tight chamber without a distinct self-expanding structure. The fluid-tight chamber may have an inlet port for admitting fluid into the chamber. A further alternative for self-expansion is for the fluid-tight chamber to be made of resilient material that self-expands to a deployed configuration, for example, towards a moulded configuration of the fluid-tight chamber.

<FIG> illustrates a second example similar to the first example of <FIG>. The main difference in <FIG> is the addition of an adjustment mechanism <NUM> for enabling the distance between the bulb <NUM> and the proximal end 10a of the tube <NUM> to be set prior to introduction into the stomach and/or in situ during or after placement in the stomach. The adjustment mechanism <NUM> may, for example, comprise a screw thread and a rotatable nut. The adjustment mechanism <NUM> may be adjusted may manual rotation using a suitable tool, or by magnetic rotation using a magnetic tool.

Referring to <FIG>, an alternative example of anchor <NUM> is illustrated comprising at least one resilient element <NUM>, expandable from a collapsed condition for introduction into the stomach, and an expanded operative condition (<FIG>) in which the resilient element <NUM> has an at least partly helix shape.

The helix shape may diverge in a radial direction progressively away from the proximal end of the tube. The helix shape may include open space between adjacent turns or windings of the helix.

Such a configuration may be advantageous to be easily collapsed for introduction, while also expanding to a relatively large size in its operative condition. The helix shape can provide atraumatic compliant engagement able to absorb and accommodate stomach contractions, even strong transient contractions, without pulling overly on the tube <NUM>. At the same time, the helix shape reliably anchors the tube <NUM> to prevent displacement through the pylorus. The anchor <NUM> can be collapsed by pulling on the free end of the helix shape using a suitable retrieval tool, allowing the device to be removed when desired.

<FIG> illustrate further examples including one or more gastric bulbs or balloons <NUM> configured to induce a feeling of satiety through contact with the stomach wall. The balloons may or may not function as gastric anchors, depending on the implementation. Where appropriate a gastric anchor <NUM> is coupled to the proximal end of the tube <NUM>.

The bulbs or balloons <NUM> may optionally be inflated with fluid (e.g. gas or liquid). A gas, for example air, may desirably cause the balloon to float with respect to stomach contents. In <FIG>, at least one (optionally more) balloon <NUM> is tethered to the proximal end of the tube <NUM>, to float upwardly with respect to the stomach contents.

In <FIG>, at least one (optionally more) balloon <NUM> has a magnetic property, such as a magnetic coating or carries one or more magnetic elements <NUM>. Magnetic repulsion between the balloon <NUM> and a same-sense magnetic element (not shown) at the proximal end of the tube <NUM> urges the balloon <NUM> away from the tube <NUM>, and towards contact with the stomach wall.

In <FIG>, multiple balloons <NUM> occupy significant space within the stomach, and bear against the stomach wall(s). The balloons <NUM> may be loose and/or captive relative to one another. The balloons <NUM> may be loose and/or captive with respect to the tube <NUM>.

In the above examples of <FIG>, the one or more balloons <NUM> are sized to permit stomach movements and contractions, and also to permit chyme to pass to the tube <NUM>.

Referring to <FIG>, the anchor <NUM> comprises a first ring <NUM> for fitting against a stomach-side of a pyloric sphincter PS, and a second ring <NUM> for fitting against a duodenal-side of the pyloric sphincter PS. The first and second rings <NUM>, <NUM> are coupled to one another for clamping the pyloric sphincter PS between the rings <NUM> and <NUM>. As can be seen in the detail of <FIG>, the first and second rings <NUM> and <NUM> have different inner and/or outer diameters from each other. In the illustrated form, one ring (e.g. the first ring <NUM>) has an inner diameter approximately greater than (or at least not substantially smaller than) the outer diameter of the other (e.g. the second ring <NUM>).

Such an anchor <NUM> firmly, yet atraumatically, attaches to the pyloric sphincter PS, providing good fixation even in the presence of strong stomach contractions. In particular, the offsetting of one ring with respect to another can reduce risk of tissue necrosis that could be caused by pinching between two identical diameter rings with the same clamping force.

The first and/or second rings <NUM> and <NUM> may be collapsible to a collapsed condition for introduction to the pylorus. The anchor <NUM> further comprises one of more connecting elements <NUM> between the rings <NUM> and <NUM>, and coupled to the rings <NUM> and <NUM> for selectively drawing the rings closer to one another for clamping the pyloric sphincter PS. In the illustrated form, the connecting elements <NUM> comprise filaments (e.g. sutures). The filaments engage the rings <NUM> and <NUM> such that pulling on the filaments draws at least one ring towards the other.

If desired, at least one of the rings <NUM>, <NUM> may also be directly attached to the pylorus, for example, by one or more tissue-penetrating fixings (similar to that shown in <FIG>, described below).

The tube (not shown) may be attached to one or more of the first and second rings <NUM> and <NUM>. The tube may be attached permanently, or via a connector, such as a magnetic connector.

Referring to <FIG>, in addition to the first and second rings <NUM> and <NUM>, the anchor <NUM> further comprises at least one inner ring <NUM> for corralling an inner peripheral edge of the pyloric sphincter PS. In the illustrated embodiment, first and second inner rings 38a and 38b are used. One of more connecting elements <NUM> between the inner rings 38a and 38b, and coupled to the rings 38a and 38b selectively draw the rings closer to one another for corralling the inner edge of the pyloric sphincter PS. In the illustrated form, the connecting elements <NUM> comprise filaments (e.g. sutures). The filaments engage the rings 38a and 38b such that pulling on the filaments draws at least one ring towards the other.

In use, the after placing the second ring <NUM>, the inner rings 38a and 38b may be placed spaced apart from the pyloric sphincter PS. The inner rings 38a and 38b are drawn together to corral the inner edge, followed by placing and/or drawing the first ring <NUM> to clamp the pylorus between the first and second rings <NUM> and <NUM>. If desired, one (or both) of the first and second rings <NUM>, <NUM> may be directly attached to the tissue of the pyloric sphincter, for example, by one or more tissue penetrating fixings <NUM>. In one example, the fixings <NUM> are staples, for example having a U-shaped form, each limb of the U-shape piercing tissue and held captive by a transverse stop 42a (e.g. defining a T-shape). Alternatively, the fixings <NUM> may be tag-pins inserted from one side of the tissue, and having a self-expanding transverse stop or wing extending from a central stalk, to hold the fixing captive on the opposite side of the tissue, preventing withdrawal from the first side.

The tube <NUM> may optionally be attached (e.g. permanently or via an assemblable connection) to one of the rings, for example, one of the inner rings 38a, 38b, as illustrated.

Referring to <FIG>, a further example of tube <NUM> is illustrated. The tube <NUM> is configured for extending from a proximal end 10a at the pylorus into the duodenum and optionally at least partly into the jejunum. The tube <NUM> may be made of plastics, such as silicone or polyurethane. The proximal end 10a is configured for direct attachment to body tissue by means of sutures or staples <NUM> that pierce the material of the tube <NUM>. In order to prevent tearing of the plastics material, the proximal end comprises a layer of suture-permeable and/or staple-permeable, reinforcing fabric <NUM>, optionally laminated to and/or incorporated within the plastics material. The fabric <NUM> may be a woven or non-woven material. The fabric <NUM> may be of polymer material, such as PET. The natural openings or spaces in the fabric material <NUM> allow a suture or fixing to pass therethrough without breaking the fiber or filament of the fabric itself. Thus the fabric can prevent tear propagation in the plastics of the tube <NUM>.

The proximal end 10a of the tube <NUM> may be flared to facilitate placement and attachment of the proximal end 10a.

Optionally, the tube <NUM> includes a duodenal anchor <NUM>, such as a stent, and/or reinforcement <NUM> across the pylorus to avoid risk of the tube <NUM> twisting due to stomach movements.

In use, the tube <NUM> may be placed into the duodenum and optionally the jejunum. A surgical stapler may be used to staple the proximal end to, for example, tissue forming the pyloric sphincter, in a similar manner to that illustrated in <FIG>.

<FIG> illustrate a further technique for fastening the tube <NUM>, such as the tube of <FIG>. Referring to <FIG>, the tube <NUM> is introduced via the patient's mouth, and placed into at least the duodenum, with the proximal end 10a of the tube <NUM> proximal of the pylorus. The tube <NUM> may be held in place temporarily by a mechanical device (not shown).

Referring to <FIG>, a tool <NUM> is guided through the mouth to the pyloric antrum. The tool <NUM> includes a hypotube needle used to pierce through the region of the tube containing the fabric <NUM>, and through the stomach wall. A pledget <NUM> having an attached suture is inserted through the fabric <NUM> and the stomach wall, via the hypotube needle, and deployed outside the stomach wall, leaving the suture trailing through the stomach wall and the fabric <NUM>.

Referring to <FIG>, the hypotube needle is withdrawn to the interior side of the stomach, and a second pledget <NUM> is parachuted over the same suture, via the hypotube, and deployed on the interior surface of the stomach wall. The suture is tightened to tightly sandwich the stomach wall and the fabric <NUM> of the proximal end of the tube, between the two pledgets <NUM> and <NUM>. The suture is knotted and cut, leaving the pledgets <NUM> and <NUM> forming an independent fastening. The same process is repeated at several different points around the periphery of the proximal end of the tube <NUM> to firmly anchor the tube <NUM> to the stomach wall. The pledgets can provide a secure attachment of the tube <NUM> and avoid irritation through rubbing during stomach contractions, because the proximal end of the tube is attached to move intimately with the stomach wall. When it is desired subsequently to remove the tube <NUM> from the stomach, a tool can be inserted into the stomach to cut the sutures, and release the pledgets <NUM> on the inside surface of the stomach wall, thereby releasing the tube <NUM>.

Referring to <FIG>, a tube <NUM> for insertion into the gastro-intestinal tract, optionally the duodenum, has an outer surface defining at least one channel <NUM> extending, at least partly, in an axial direction of the tube. In one form, the channel <NUM> may be substantially axial, for example, in the form of a fluted surface (<FIG>). Alternatively, the channel may be helical in shape, in the form of a threaded surface (<FIG>). The channel <NUM> permits bowel juices, for example, pancreatic juices, to flow as in the efferent bowel, along the exterior of the tube <NUM>, and can avoid the juices becoming trapped by contact between the tube <NUM> and the bowel tissue.

Referring to <FIG> and <FIG>, a tube <NUM> is illustrated for supplementing an anastomosis <NUM>, for example a gastro-jejunal anastomosis. The anastomosis may, for example, be between the bottom of the stomach and the jejunum, or it may be between a cut-down stomach and the jejunum (as illustrated in <FIG>). The tube <NUM> may optionally comprise an anchor <NUM> for anchoring at the anastomosis <NUM>. The anchor may include any of the features described above; optionally the anchor may include the features of any of <FIG>.

The tube <NUM> may function to prevent or reduce reflux of pancreatic juices (illustrated by arrows <NUM>) originating from the pancreas <NUM> from passing through the anastomosis <NUM>. For example, the tube <NUM> is placed into the part of the jejunum leading to the large intestine. Stomach contents (arrows <NUM>) passing through the anastomosis are directed in the normal flow direction towards the large intestine. Pancreatic juices arriving (arrows <NUM>) from upstream in the jejunum are directed outside the tube <NUM> and thus away from the anastomosis <NUM> and also towards the large intestine, thereby reducing the possibility of reflux of these juices through the anastomosis <NUM>.

The tube <NUM> may also be configured with a directional flow characteristic, to admit flow of stomach content (e.g. chyme) in a first direction through the tube <NUM> away from the stomach (arrow <NUM>), and to obstruct flow in an opposite second direction through the tube <NUM>. The one-way characteristic can also block reflux of bowel juices, for example, pancreatic juices in the jejunal loop <NUM> , through the anastomosis <NUM> towards the stomach, thereby reducing stomach discomfort for the patient.

The one-way characteristic of the tube may be implemented by at least one, optionally multiple, flaps <NUM> (<FIG>) provided on the interior of the tube <NUM>. The flaps may have a flexible and/or loose annular shape, or comprise individual arcuate segments. The flaps <NUM> are directed towards the outlet. Flow in the first direction (arrow <NUM>) pushes the flaps <NUM> against the wall of the tube <NUM> to admit flow. Flow in the reverse direction tends to push the flaps <NUM> inwardly towards the centre of the channel, to narrow the channel in the tube <NUM>, and hence obstruct flow. Alternatively, the tube <NUM> may itself be collapsible, like a sock, to perform a one-way valving function. Flow in the first direction opens and distends the tube <NUM>. Flow in the opposite second direction collapses the tube on itself, to obstruct flow.

Referring to <FIG> and <FIG>, a further illustrated technique for treating diabetes or obesity, involves application of at least one tissue-penetrating fixing <NUM> to reduce the natural volume of the stomach by creating one or more pleats <NUM> (or artificial folds) in the stomach wall. In the illustrated example, the fixing <NUM> is a staple, optionally having a U-shaped profile, with T-shaped limb ends, as described above. The fixing may, for example, be placed by an endoscopic technique or a laparoscopic technique.

The one or more pleats <NUM> may extend in a direction that is generally (i) from top to bottom of the stomach, and/or (ii) from the oesophagus to the pylorus. Such pleats <NUM> can form a generally sleeve shape cavity or passage in the stomach.

Referring to <FIG>, the stomach reduction pleats <NUM> can also be used in combination with a tube <NUM>, and optionally in combination with an anastomosis <NUM>, for example, a gastro-jejunal anastomosis <NUM>. The pylorus P can be closed or plugged by a closure device <NUM>. The closure device <NUM> may, for example, comprise rings similar to those described for <FIG> above, for anchoring to the pyloric sphincter.

<FIG> illustrate further examples of fixation of a tube <NUM> to a pylorus P, using tissue-penetrating fixings <NUM>.

Referring to <FIG>, each fixing generally comprises two end pieces in the form of a head <NUM> and a foot <NUM> coupled via connecting element <NUM>. The head <NUM> and foot <NUM> have a generally atraumatic shape, for example, a rounded rod shape. In the illustrate examples, the head <NUM> and foot <NUM> are tubular, enabling the pieces to be carried around a penetration needle <NUM> (<FIG>) for introduction and deployment. The head <NUM> and foot <NUM> may be rigid or semi-rigid elements, optionally made of shape memory alloy, for example nitinol.

The connecting element <NUM> may be rigid or flexible. In the example of <FIG>, the connecting element <NUM> is generally linear. In the example of <FIG>, the connecting element <NUM> has the form of an elongate spring, for generating a compressive load when the spring is extended.

At least the head <NUM>, and optionally the foot <NUM> can be brought into a generally non-deployed configuration (<FIG>) in which the head (and optionally the foot) extends side by side with the connecting element, for introduction in a streamlined shape. In a deployed configuration (<FIG>), the head (and optionally the foot) is moved to project laterally on either side of the connecting member.

Referring to <FIG> and <FIG>, a tool <NUM> is illustrated for attaching a ring <NUM> of a duodenal tube <NUM> to a pylorus P of a patient, using the fixings <NUM>.

The tool <NUM> comprises a plurality (e.g. three in the illustrated form) of first elongate supports <NUM> attached to the ring <NUM> for introducing the ring to the pylorus, and for holding the ring during deployment of the fixings. For example, the first elongate supports <NUM> may be attached by suture loops <NUM> to an inner core of the ring <NUM>. The suture loop <NUM> can pass within the elongate support, and be released from one end when it is desired to separate the elongate support <NUM> from the ring <NUM>.

The tool <NUM> further comprises a plurality (e.g. three in the illustrated form) of second elongate supports <NUM> each having a penetration needle <NUM> at its free end. A security suture <NUM> may pass within the the second elongate support, and loop through or around the fixing <NUM> to ensure that the fixing <NUM> will not detach prematurely from the needle <NUM>.

The tool <NUM> further comprises a multi-lumen catheter shaft <NUM> having lumen for receiving the pluralities of first and second elongate supports <NUM> and <NUM>. The first and second supports <NUM> and <NUM> may be distributed alternately in a circumferential direction, such that each first elongate support <NUM> is positioned between two adjacent second elongate supports <NUM>, and vice versa. At least the second elongate supports <NUM> are slidable axially between axially extended and axially retracted positions, for causing the needles <NUM> to penetrate through tissue, as illustrated later below. The first elongate supports <NUM> may also be axially slidable if desired.

The tool <NUM> further comprises a constraining sheath <NUM> slidable over the catheter shaft <NUM>. The constraining sheath <NUM> can constrain the first and second elongate supports <NUM>, <NUM> to a radially compressed configuration (<FIG>) for introduction through the stomach to the duodenum. Retraction of the constraining sheath <NUM> allows the first and second elongate supports <NUM> and <NUM> to diverge or splay outwardly to a radially enlarged configuration (<FIG>). The first elongate supports <NUM> and/or the second elongate supports <NUM> may be pre-shaped to splay outwardly when the constraining effect of the sheath <NUM> is removed. The constraining sheath may also serve to restrain the ring <NUM> in a radially compressed configuration for delivery. In a similar manner to that already described above, the ring may be expandable to its operative size when released from the sheath <NUM>.

The multi-lumen shaft <NUM> has a hollow interior channel <NUM> defining an accommodation space for the tube <NUM>. The tool <NUM> may further comprise a gripper <NUM> for releasably gripping and controlling the distal end of the tube <NUM>.

<FIG> illustrate a procedure for introducing and attaching a tube <NUM> through the stomach, using the tool <NUM>. In <FIG>, the tool <NUM> housing the tube <NUM> and the ring <NUM> in their collapsed configurations, is advanced through the stomach S and through the pylorus P into the duodenum D.

Referring to <FIG>, the distal end of the tube <NUM> is advanced out of the sheath <NUM> by advancing the gripper <NUM> into the duodenum, over a guidewire G.

Referring to <FIG>, the restraining sheath <NUM> is retracted with respect to the shaft <NUM>, to release the ring <NUM> attached to the proximal end of the tube <NUM>, and allow the ring <NUM> to expand towards its functionally operative size.

Referring to <FIG>, pulling slightly on the first elongate supports <NUM> can seat the ring <NUM> against the pyloric sphincter tissue on a first (duodenal side). Further retraction of the sheath <NUM> allows the second elongate supports <NUM> to expand to present the needles <NUM> carrying the fixings <NUM>.

Referring to <FIG>, the needle <NUM> carrying the fixing is caused to penetrate through the pyloric sphincter tissue and into the ring <NUM> by advancing or sliding a second elongate support <NUM> distally. In the illustrated example, the needle <NUM> also penetrates through the ring <NUM>, until the head <NUM> of the fixing passes to the opposite side. The first elongate support can remain attached to the ring <NUM> to provide a counter support for the ring <NUM> while the needle <NUM> is advanced.

Referring to <FIG>, the second elongate support <NUM> is partly retracted, allowing the head <NUM> of the fixing <NUM> to deploy laterally, and anchor against the ring <NUM> from the distal side.

Referring to <FIG>, the second elongate support <NUM> is fully retracted, allowing the foot <NUM> of the fixing also to deploy laterally, and anchor against the pyloric sphincter from the opposite side to the ring <NUM>. The security suture for the fixing may be released by pulling one end of the suture, in order to allow the needle <NUM> to separate from the fixing <NUM>.

Finally in <FIG>, the first elongate support <NUM> is released from the ring <NUM>, leaving the ring <NUM> permanently and securely attached to the pyloric sphincter. The restraining sheath <NUM> can be advanced to provide an atraumatic cover over the exposed ends of the first and second elongate supports <NUM> and <NUM>.

Claim 1:
A tube configured for insertion into the gastro-intestinal tract, the tube comprising an anchor (<NUM>) for anchoring the tube (<NUM>) with respect to a pylorus of a patient, the anchor comprising a gastric bulb (<NUM>) coupled or couplable to a proximal end of the tube, the gastric bulb (<NUM>) expandable from a collapsed condition for introduction into the stomach, to an operative condition within the stomach,
wherein the gastric bulb (<NUM>) comprises a fluid-tight chamber, and an inlet port (<NUM>) for (i) allowing fluid to be drawn into the chamber as the gastric bulb expands to its operative condition, and/or (ii) admitting fluid into the chamber for inflating the gastric bulb,
wherein the bulb comprises a passage configured for allowing chyme to pass through the bulb,
wherein the gastric bulb (<NUM>) is coupled to the tube by one or more tethers (<NUM>) and/or struts and characterised in that the tube comprises a cuff or stent (<NUM>) for resisting displacement from the implanted position towards the stomach.