WO2019158264A1

WO2019158264A1 - Sealing stent

Info

Publication number: WO2019158264A1
Application number: PCT/EP2018/086513
Authority: WO
Inventors: Boris Vestweber
Original assignee: Boris Vestweber
Priority date: 2018-02-19
Filing date: 2018-12-21
Publication date: 2019-08-22
Also published as: DE102018103618A1

Abstract

The invention relates to a stent (1) for introduction into a hollow organ of the human and/or animal body, preferably into the gastrointestinal tract, particularly the intestine, having a tubular hollow body (2) which is open at the axial end faces. The hollow body has an outer wall (5) and an inner wall (4), wherein a support system (7) is provided in an intermediate space between the inner wall and the outer wall to stabilise the shape of the stent.

Description

SEALING STENT

The invention relates to a stent for introduction into a hollow organ of the human and/or animal body, preferably into the gastrointestinal tract, particularly the intes- tine, having a tubular hollow body which is open at the axial end faces.

A stent in the medical field is introduced and placed as an implant in the human or animal body, where it serves on the one hand to widen vessels or hollow organs and keep them open, to counteract vessel constriction following an infarction situa- tion for example. On the other hand, a further application area for stents is in clos ing off leaks, particularly in hollow organs such as the intestine or oesophagus. Such leaks (anastomoses) may occur for example as a complication after a surgi cal procedure in the gastrointestinal tract. Because an anastomosis often results in the contents of the organ leaking into the abdominal cavity, such an occurrence typically results in serious infections and abscess formation, particularly if it is the contents of the intestine that leak. Such a situation can be extremely dangerous, especially for patients who are recovering from surgery.

Stents have been used for quite some time to close off such undesirable anasto- moses, wherein they line the hollow organ in the region of the anastomosis in the form of a tube. Such stents are often designed to expand automatically. However, the drawback of the known stents of the kind described is that they must be an chored in the surrounding tissue in order to prevent the stent from slipping or be coming dislodged. The mechanical means usually used for this, such as hooks or the like, pose a high risk of injury for the patient. To ensure that the stent remains firmly in place and reliably ensures that the anastomosis remains blocked even when the patient moves, or when the organ itself moves - as a result of normal per istalsis, for example, a sufficient number of corresponding fixing means with suffi cient anchoring capability must be provided. However, this arrangement entails a major difficulty of its own, that of finding a compromise according to which the stent is fixed firmly in place but without irritating or even injuring the surrounding tissue by protruding or cutting too deeply into the tissue with the fixing means. Moreover, it cannot usually be guaranteed that a hose-like or tubular stent will lie against the irregularly shaped inner wall of a hollow organ such as the intestine in a totally sealing manner, or at least not permanently. Given this situation, the object of the present invention is to overcome the afore mentioned drawbacks and provide an option by which an anastomosis in a hollow organ may be sealed safely, wherein the treatment should entail the least possible limitations for the patient and low cost. The object as stated above is solved with a stent having the features of the subject matter of Claim 1. Advantageous refinements are the subject matter of the sub claims.

The stent according to the invention has the form of a cylinder or tube, which is also the basis for known stents. Consequently, it does not interfere with the continuity of the organ it is being used to treat. Good dimensional stability and improved posi tioning against the irregularly shaped inner wall of a hollow organ such as the intes tine than is assured by the stents known from the related art, and thus also a suc cessful, durable closure of an anastomosis is achieved according to the invention with a support system which is embedded in a double-walled outer casing of a hol low body which forms the tubular base element of the stent. In principle, the sup port structure of the support system may be of any shape and may be selected ac cording to a given application, and prevents the stent from collapsing either spon taneously or under the effects of external pressure.

An inner wall separates the support structure from the lumen of the stent's hollow body and serves as a first seal to prevent the contents of the organ from escaping through the support structure in the region of the anastomosis. A further seal of the hollow organ concerned is also created by the outer wall of the hollow body, which also serves to ensure a close-fitting position against the inner wall of the hollow or gans. The intermediate space between the inner and outer walls of the hollow body, in which the support system is located, is preferably closed off at its extremi ties to prevent the contents of the organ from leaking into it. The double-walled de sign of the hollow body mantle thus also prevents contents of the organ from adher- ing to the support structure both outwardly, i.e. for treating the anastomosis, and inwardly, and from being transported further.

Given its advantageous properties, the stent according to the invention is also par- ticularly suitable for use in preventing the formation of anastomosis, or it may easily be applied for a certain time during and after healing of an anastomosis to provide temporary protection against the formation of other anastomoses.

In the stent according to the invention, two separate structures, namely the tubular hollow body and the support system assume the sealing function and are given the mechanical strength required therefor. This in turn serves to simplify the construc tion of the stent, and the costs of manufacturing it are lowered significantly com pared with known stents. Support rings surrounding the lumen of the hollow body radially are particularly suitable for constructing the support system. Providing they are sufficiently rigid, support rings in the lining prevent the hollow body as such from collapsing or oth erwise undergoing undesirable deformation, which would compromise the seal over the anastomosis. The use of support rings allows the construction of the support system to be relatively simpler and thus also less expensive. Firstly, support rings only need to be arranged with a sufficiently small axial separation between them in order to provide a certain supporting effect. However, the lumen does not need to be completely sheathed radially by support material over the entire length of the hollow body. Secondly, the inner wall and the outer wall of the hollow body in the stent according to the invention may also be made simply using inexpensive mate rials. In particular, for example, a polymer layer or polymer tube may be manufac tured with little production expense using standard methods such as casting pro cesses or by extrusion. An elastic design offers further advantages in terms of positioning the stent flush against the organ wall and therewith also the sealing effect. Consequently, prefera bly at least one support ring is made from an elastic material, particularly an elastic plastic or contains an elastic material, particularly an elastic plastic. In addition, the inner wall and/or the outer wall may consist of a plastic or contain a plastic. The inner and/or outer wall is preferably also of elastic construction, so that the stent is given its shape by the support system and the stent is also able to adapt to the shape of the surrounding hollow organ.

A ribbed outer profile of the hollow body's outer surface is created by a support sys tem with support rings in conjunction with an elastic outer wall of the hollow body. This serves to improve the fixation of the stent in the desired region. In particular, the danger of the stent slipping along the hollow organ or even coming loose spon- taneously is reduced further. At the same time, compared with sharp-edged fixing means such as hooks, the fixing of the stent is carried out in a manner that is ex tremely gentle on the tissue.

A particularly advantageous embodiment of the support system with support rings is one in which an inner hollow space is provided in at least some of the support ring, which space is preferably filled with a fluid. A filling with air is preferably used in this context. According to the invention, however, other gases and/or liquids are also suitable for filling the hollow space. The shape and size and/or stiffness of the support rings may be adjusted via the internal pressure in the hollow spaces.

The production cost for various types of support systems and/or support rings may be reduced further by using an elastic material for the support system and/or sup port rings. For example, with regard to material selection and shape it is then suffi cient at first to produce only one kind of support ring and to give the support ring its final size, shape and stiffness by filling of more or less fluid into the support ring to adjust the internal pressure in the hollow space before the hollow space is sealed. This enables various types of support systems with support rings to be offered without having to set up a dedicated production line for each variation. In a particularly preferred embodiment of the stent according to the invention, the support rings are in fluid communication with each other. The fluid connection be tween the support rings may be provided by one or more axial channels. The chan nels may be made from the same material as the support rings or from a different material. The layout and arrangement of the channels may also be designed at will. In particular, an arrangement parallel to the lengthwise axis of the hollow body is not necessary. With the fluid connection, it is possible to reach a balance in terms of fill quantity or internal pressure in the support rings generally over the entire length of the support system. This increases homogeneity in terms of deformability, stiffness and therewith also the ability to adapt the shape of the hollow body and the stent to a shape dictated by the hollow organ.

A particularly flexible and easily usable variant of the stent according to the inven tion is one in which the support system, particularly the support rings is/are embod ied in such a way that the shape and/or size of the support systems and therewith of the hollow body, i.e., the stent as such may be altered by introducing or expelling a fluid, i.e. air for example. The internal pressure in the support system may be in creased or reduced via a corresponding supply line, which preferably runs from the stent to outside the patient's body and is connected to the fluid chambers of the support system simply by connecting a pressure regulating apparatus, a pump for example. This also enables the stent to be expanded and/or deflated subsequently. Thus, an extensive range of options is available to the treating physician to take appropriate steps in the event of a change to the patient's clinical situation.

Furthermore, a stent having the aforementioned properties can also be implanted easily. The stent can first be brought to the site which is affected by an anastomo sis through the hollow organ. In order to position it flush against the wall of the or gan, the stent may then be expanded by increasing the pressure in the support sys tem, i.e. inflating it, as it were. In this context, the expansion of the stent is carried out under control at all times, and if necessary may also be interrupted, reversed and/or repeated. This is a significant advantage over conventional, self-expanding stents which generally do not offer this capability at all.

The stent according to the invention is advantageously also able to be implanted easily using a standard coloscope and/or with the aid of a circular stapler.

The outer and/or inner wall of the hollow body is/are preferably designed so that at least regions thereof are permeable for fluids and/or solids. In particular, the outer wall is perforated correspondingly for this purpose. According to the invention, a semi-permeable design of the outer wall may also be provided. Accordingly, per meability may also be assured only in one direction of passage and/or selectively only for certain substances. This enables any organ contents that have leaked or other liquids to return to the hollow organ through the mantle of the hollow body, but prevents further escape or repeated escape. A porous material may be provided in the intermediate space between the inner and outer walls of the hollow body, surrounding the rest of the support system and enhancing its effect, or it may itself be the support system. Alternatively or addition ally, the material in the intermediate space may also be plastically and/or elastically deformable. This enables position of the hollow body of the stent flush against the inner wall of the organ to be improved, and enhances the sealing effect of the stent for treating an anastomosis. In conjunction with an at least partly permeable outer wall of the hollow body, a porous material in the mantle of the hollow body may also serve to collect liquid from the organ wall and to a certain degree also to absorb and/or bind even organ contents that have leaked from the organ.

A particularly preferred variant of the stent provides that at least regions of the out er wall of the hollow body are designed to be permeable for fluids and/or Solid ma terial, while the inner wall of the hollow body is impermeable and thus seals the lu men of the hollow body off from the outside area, i.e. the area in which the outer wall, the intermediate space between the walls, and the support system located. In conjunction with a porous material provided optionally in the intermediate space as described in the previous section, this then allows material from the area surround ing the stent - particularly including leaked organ contents - to be collected and bound in the mantle of the hollow body but without the need to have permeability between the lumen of the hollow body and site where the anastomosis occurs and/or the area surrounding the hollow organ, which allows organ contents to es cape.

Improved collection and binding of material outside the hollow body of the stent can be achieved by creating a negative pressure in the intermediate space between the outer wall and the inner wall. For this purpose, the stent may be equipped with a vacuum hose, via which a negative pressure is created in the intermediate space of the mantle of the hollow body of the stent by means of a corresponding device, a vacuum pump for example. The negative pressure relative to the pressure prevail ing in the area surrounding the hollow body has the effect of sucking material, par- ticularly any organ contents that have already leaked, into the stent through a cor respondingly permeably constructed outer wall and preferably transporting it out of the intermediate space via the vacuum hose. The risk of an infection in the ab dominal cavity from leaked intestinal content for example is thus effectively re- duced. A further advantage of negative pressure in the hollow body mantle consists in that the aspiration effect to the outside causes the hollow body to lie more closely against the inner wall of the hollow organ, creating a better seal.

A vacuum hose may be fed through the inner wall of the hollow body at a corre- spondingly sealed bushing or connection point, and through the lumen and the hol low organ to the region outside the patient's body, where it is accessible for medical personnel for example. Of course, a negative pressure may be created and adjust ed in the intermediate space between the walls at any time, independently of any pressure setting in the support system to expand and deflate it.

In order to support the treatment, the stent may also contain or include an active substance which is released at a corresponding location in the hollow organ in which the stent is implanted. Such an active substance may be for example a sub stance that promotes healing, inhibits inflammation, or has analgesic or antiseptic properties. A particularly advantageous option for introducing an active substance via the stent according to the invention consists in coating at least a region of an outers side of the outer wall of the hollow body. This enables the active substance to take effect specifically and locally at the site of an anastomosis. The dimensions of the stent according to the invention are ideally adapted to the anatomy of a hollow organ that is to be treated. Particularly the length of the hollow body is practically freely selectable given the construction of the stent according to the invention. The outer diameter or the luminal diameter of the hollow body is preferably between 10 mm and 60 mm on average, more preferably between 15 mm and 40 mm, particularly preferably between 20 mm and 30 mm. However, the aforementioned values merely represent preferred dimensions, with which the stent according to the invention in the applied state matches an average anastomosis of the human animal body. With an elastic construction mantle of the hollow body and/or the support system, the size and shape may be changed, particularly after- wards and according to needs, so that the values may differ from those given above without departing from the scope of the invention.

In the following section, the invention will be explained in greater detail with refer- ence to exemplary embodiments. In so doing, all of the features described and rep resented in the drawing are considered to be part of the present invention individu ally in their own right, independently of their combination in the examples illustrated or references thereto in the claims.

In the drawing:

Fig. 1 is a schematic representation of a longitudinal cross-section through a preferred embodiment of a stent according to the invention, Fig. 2 is a schematic representation of a transverse cross-section through the stent of Fig. 1 ,

Fig. 3 is a schematic representation of a preferred variant of a support sys tems of a stent according to the invention in perspective view, and

Fig. 4 is a schematic representation of a longitudinal cross-section through a possible application situation for the stent according to the invention.

Fig. 1 shows a particularly preferred embodiment of a stent 1 according to the in- vention. The base element of the stent 1 if formed by a hollow body 2. The hollow body 2 has a hose-like or tubular shape, with an elongated, approximately cylindri cal lumen 3.

The mantle of the hollow body 2 has a multilayer, particularly elastic construction. An inner wall 4 of the hollow body 2 surrounds the lumen 3 radial. In the embodi ment shown here, the inner wall 4 is designed to be impermeable to liquid and gas, and so seals the lumen 3 off from the external regions. The hollow body 2 further has an outer wall 5, at least a region of which is designed to be porous in the present example. In this way, liquid, gaseous and/or solid mate rial is able to pass through the outer wall to a certain degree. An intermediate space 6 is formed between the inner wall 4 and the outer wall 5 of the hollow body 2. In the intermediate space 6 there is a support system 7 which lends the stent 1 and the hollow body 2 thereof a desired shape and corresponding stability in this shape. In the preferred variant shown here, the support system 7 comprises a plurality of support rings 8 which surround the lumen 3 of the hollow body 2 radially. The sup port rings 8 prevent the hollow body 2 from collapsing or being pressed together if pressure is applied from the outside. Thus in particular by means of the support rings 8 the support system 7 ensures the integrity of the lumen 3. The support rings 8 do not have to be arranged equidistantly from each other as illustrated, they may also be more or less closely to each other and/or at varying distances from each other according to needs.

In the present case, the support rings 8 have an inner hollow space 9 which is filled with a fluid, particularly air. Finally, the internal pressure in the hollow space 9 ena bles the support rings 8 - which are made from an elastic material - to keep their shape, size and resistance to mechanical deformation, and impart the intended configuration to the hollow body 2. The support rings 8 or the hollow spaces in the support rings 8 are in fluid commu nication with each other. In the present example, the fluid connection between the support rings 8 is created in the form of axial connecting channels 10. The pressure may be balanced between the hollow spaces 9 of different support rings 8 by means of the channels 10. Thus preferably all hollow spaces of the support rings 8 together with the connecting channels 10 form a common fluid system of the sup port system 7.

A fluid may be supplied to the fluid system and/or a fluid contained therein may be removed partly or completely via a supply line 1 1. In this way it is possible to change the shape and/or size of the support system 7 and thus also of the hollow body 2 itself via the supply line 1 1. In particular, the size and/or shape may also be changed after it has been implanted in the patient's affected hollow organ. For this, the supply line 1 1 preferably extends as far as the region outside of the patient's body. The stent 1 may be expanded and/or deflated in targeted, controllable man- ner by means of a pressure changing device such as a pump or similar, which is not represented in full detail.

In the present embodiment, a formable and porous, i.e. sponge-like and/or foam like material is provided in the intermediate space 6 between the inner wall 4 and the outer wall 5 of the hollow body 2. This material enables improved positioning of the hollow body 2 flat against an irregular surface.

Given the absorbent properties of the porous material, substances, especially fluid substances from the region around the stent 1 can be taken up and bound by a permeable outer wall 5.

In the particularly preferred variant of the stent 1 according to the invention repre sented here, provision is also made for evacuating the intermediate space 6 be tween the outer wall 5 and the inner wall 4 with the porous material located therein. In the present example, evacuation, i.e., creating a negative pressure in the inter mediate space 6 relative to the region surrounding the hollow body is possible via a vacuum hose 12, which communicates with the intermediate space 6 through the impermeable inner wall 4 via a connection point 13. The vacuum hose 12 is preferably accessible due to the fact that it extends to a point outside the patient's body. There, an apparatus for creating a negative pres sure, i.e. a vacuum pump or similar - not shown in detail in the drawing - may be connected. By this means, a stent 1 that has already been implanted may be acti vated and deactivated without difficulty for the purposes of the evacuation function. With the aid of an evacuation function as described earlier, even relatively large quantities of material can be collected from the area surrounding the hollow body 2, and then bound and/or removed.

Fig. 2 shows a cross-section through the stent 1 that is represented in lengthwise cross-section in Fig. 1. The section chosen for display corresponds to the sectional plane II indicated in Fig. 1 by the dot-dashed line. In the representation of Fig. 2, the multi-wall construction of the mantle of the hollow body 2 with an inner wall 4 and an outer wall 5 and an intermediate space 6 between them are clearly visible. The arrangement of the axial connecting channels 10 at multiple positions around the circumference of the hollow body 2 is also evident. Of course, the number and arrangement of connecting channels 10 actually provided may differ from those il lustrated within the scope of the invention. In particular, an equidistant arrangement and a uniform distribution on the circumference of the hollow body 2 are not essen tial, and/or a larger or smaller number of connecting channels 10 may be provided.

The support system 7 is shown in stand-alone form, i.e. without further elements of the hollow body 2, particularly without the inner wall 4 and the outer wall 5 and the porous material in the intermediate space 6 between the walls 4, 5. In this repre sentation, the support rings 8 and the axial connecting channels 10 are visible. In the representation according to Fig. 3, unlike that of Fig. 2 the axial connecting channels 10 are arranged in three (instead of four) straight segments along the longitudinal extension of the hollow body 2. Of course, the channels 10 may be ar ranged differently, and in particular a different number of connecting channels 10 may be provided.

According to the invention in particular it is not essential for a connecting channel 10 to run between two support rings 8 precisely in a notional extension of another connecting channel 10 between two other support rings 8. Moreover, the connect ing channels 10 may also extend in a direction which is not parallel to each other and/or to the lengthwise axis of the hollow body 2. Thus, it is also possible accord ing to the invention for the connecting channels 10 to extend in a spiral formation, for example, or even for the entire support system 7 to be formed as a spiral.

The embodiments presented here are expressly without limiting effect on the scope of the invention.

Fig. 4 shows an example of a typical application situation for the stent 1 according to the invention. In the example shown, the stent 1 is implanted in a patient's intes tine 14 and lines the intestine in the region of an anastomosis 15, sealing the intes tine 14 to prevent the leak of intestinal contents 16. In the situation shown in Fig. 4, some of the contents of the intestine 16 have already leaked through the anasto mosis 15 into the area surrounding the intestine 14, i.e. the abdominal cavity. The stent 1 according to the invention now prevents more intestinal contents 16 from escaping.

Not only is a good sealing effect achieved in the region of the anastomosis 15 with the stent 1 according to the invention, the continuity of the intestine 14 is also pre served. Consequently, when the stent 1 according to the invention is used it is not necessary to provide an artificial stoma, for example, which entails substantial limi- tations in the daily life of the patient and corresponding complaints. The contents of intestine 16 can largely pass through the stent 1 or the hollow body 2 via the lumen 3 thereof unobstructed. It is evident that because of its elastic inner wall 4 and par ticularly its elastic outer wall 5 the hollow body 2 can easily be adapted to the shape of the intestine 14 and positioned to lie closely against the inner intestinal wall 17.

The support rings 8 create a surface profile in the form of a ribbed structure on the elastic outer surface of the hollow body 2, i.e. on the outer wall 5. The external shape this lends the hollow body 2 causes it to press its outer wall 5 against the in- ner intestinal wall 17 a little more strongly in the region of each of the support rings 8, pressing them slightly inwards. In this was, the stent 1 is affixed firmly and se curely in its predetermined position and secured against unintended shifting.

Healing of the injured wall of the intestine 14 may be supported and accelerated for example with the aid of a coating of active agent - not shown in detail - applied to the outside of the outer wall 5 of the hollow body 2.

In the present example, the hollow body 2 has a luminal diameter of about 25 mm. Ultimately, however, the invention extends to stents 1 having a construction con- sistent with the inventive thought regardless of their diameter, length and/or any of their other proportions.

Although a large number of features represented in the embodiments presented here have been described in combination, each feature is to be considered a sepa- rate aspect of the invention in its own right, and may finally be realised in any com- bination with other features or alone without departing from the scope of the inven tion.

List of reference signs:

1 Stent 10 Connecting channel

2 Hollow body 1 1 Supply line

3 Lumen 12 Vacuum hose

4 Inner wall 15 13 Connection point

5 Outer wall 14 Intestine

6 Intermediate space 15 Anastomosis

7 Support system 16 Contents of intestine 8 Support ring 17 Inner intestinal wall

9 Hollow space

Claims

1. Stent (1 ) for introduction into a hollow organ of the human and/or animal body, preferably into the gastrointestinal tract, particularly the intestine (14), having a tubular hollow body (2) which is open at the axial end faces, characterized in that

the hollow body (2) has an inner wall (4) and an outer wall (5), wherein a support system (7) is provided in an intermediate space (6) between the in ner wall (4) and the outer wall (5) to stabilise the shape of the stent (1 ).

2. Stent according to Claim 1 , characterized in that the support system (7) in cludes a plurality of radial support rings (8), preferably wherein at least some of the support rings (8) have an inner hollow space (9) which is at least par tially filled preferably with a fluid, in particular air.

3. Stent according to Claim 2, characterized in that the support rings (8) are in fluid communication with each other particularly via at least one particularly axially extending connecting channel (10).

4. Stent according to any one of the preceding claims, characterized in that the support system (7), in particular the support rings (8), is designed in such manner that the shape and/or size thereof can be altered by introducing or removing a fluid, particularly air.

5. Stent according to any one of the preceding claims, characterized in that at least regions of the outer wall (5) of the hollow body (2) is/are permeable to fluids and/or solid matter, in particular perforated, and the inner wall (4) of the hollow body is impermeable, semi-permeable or permeable to fluids and/or solid matter.

6. Stent according to any one of the preceding claims, characterized in that a porous, particularly a sponge-like and/or foam-like material is provided in the intermediate space (6) between the inner wall (4) and the outer wall (5).

7. Stent according to any one of the preceding claims, characterized in that the hollow body (2) is constructed in such manner that negative pressure rela tive to the pressure outside the hollow body (2) can be created in the inter mediate space (6) between the inner wall (4) and the outer wall (5) of the hollow body (2).

8. Stent according to any one of the preceding claims, characterized in that the outside of the outer wall (5) is furnished with a coating of active agent at least in regions thereof.

9. Stent according to any one of the preceding claims, characterized in that at least one support ring (8) is made from an elastic material, particularly an elastic plastic, or includes an elastic material, particularly an elastic plastic, and/or that the inner wall (4) and/or the outer wall (5) is made particularly from an elastic plastic or particularly includes an elastic plastic.

1 0. Stent according to any one of the preceding claims, characterized in that the outer diameter or the luminal diameter of the hollow body (2) is between 10 mm and 60 mm on average, preferably between 15 mm and 40 mm, more preferably between 20 mm and 30 mm.