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Patent Searching and Data


Title:
STENT
Document Type and Number:
WIPO Patent Application WO/2018/068106
Kind Code:
A1
Abstract:
Stent (1) for connecting a first artery (14) to a second artery (15), wherein the stent has a head (12) and a tail (11), wherein the tail is elongate and has a diameter such that, in expanded state of the stent, the tail presses radially against an inner wall of the first artery, and wherein the head has a plurality of hook elements (9) which in the expanded state of the stent extend radially outward so that the head is suitable to hook-fixedly in the second artery via an incision.

Inventors:
HAENEN FILIP (BE)
PALMERS CHARLOTTE (BE)
Application Number:
PCT/BE2017/000044
Publication Date:
April 19, 2018
Filing Date:
September 29, 2017
Export Citation:
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Assignee:
HAENEN FILIP WALTER NICOLE (BE)
PALMERS CHARLOTTE (BE)
HAENEN LUC (BE)
International Classes:
A61B17/11; A61F2/915; A61F2/966
Domestic Patent References:
WO2001026562A12001-04-19
Foreign References:
US7691140B22010-04-06
US20130226285A12013-08-29
EP2929859A12015-10-14
US20100130995A12010-05-27
US20120065652A12012-03-15
US7063711B12006-06-20
US20070276462A12007-11-29
Other References:
None
Attorney, Agent or Firm:
PHILIPPAERTS, Yannick (BE)
Download PDF:
Claims:
Claims

1. Stent for connecting a first artery to a second artery, wherein the stent has a head and a tail, wherein the tail is elongate and has a diameter such that, in expanded state of the stent, the tail presses radially against an inner wall of the first artery, and wherein the head has a plurality of hook elements which in the expanded state of the stent extend radially outward so that the head is suitable to hook fixedly in the second artery via an incision.

2. Stent as claimed in claim 1 , wherein in the expanded state of the stent the tail has a plurality of protrusions which function as barb to at least partially prevent axial movement of the tail relative to the inner wall.

3. Stent as claimed in claim 2, wherein the plurality of protrusions extend at least partially radially outward from an outer surface of the tail in the expanded state of the stent.

4. Stent as claimed in claim 2 or 3, wherein the plurality of protrusions extend at least partially in the direction of the head of the stent.

5. Stent as claimed in any of the foregoing claims, wherein each hook element has a distal end which in the expanded state of the stent extends at least partially in the direction of the tail of the stent.

6. Stent as claimed in claim 5, wherein in the expanded state of the stent the distal end of each hook element is located at a distance from the tail in radial direction.

7. Stent as claimed in claim 6, wherein the distance is at least 0.3 mm, preferably at least

0.4 mm.

8. Stent as claimed in any of the claims 5-7, wherein each hook element has a proximal end which in the expanded state of the stent extends substantially in line with the tail, and wherein each hook element further comprises a curved hook segment which connects the proximal end to the distal end.

9. Stent as claimed in any of the foregoing claims, wherein the plurality of hook elements comprise at least six hook elements distributed over a periphery of the stent.

10. Stent as claimed in any of the foregoing claims, wherein the tail and the head extend in the compressed state of the stent substantially as a cylinder of substantially constant diameter so that the tail and the head lie mutually in lie.

11. Stent as claimed in any of the foregoing claims, wherein the stent is manufactured from nitinol.

12. A set of a catheter and a stent as claimed in any of the foregoing claims, wherein the catheter comprises an expanding mechanism for the stent, wherein the catheter is further connected to a guide wire which is coupled to the expanding mechanism in order to control expanding of the stent.

13. Set as claimed in claim 12, wherein the expanding mechanism is formed by a sheath provided for the purpose of enveloping the stent in the compressed state and wherein the sheath is movable over the stent, wherein the movement is drivable via the guide wire.

14. Method for connecting a first artery to a second artery, wherein the method comprises of:

- preparing the first artery so that the first artery has an open end which is movable;

. making an incision in a wall of the second artery;

- moving the open end of the first artery to the incision;

- positioning the stent of any of the claims 1-11 so that the tail of the stent extends in the first artery and so that the head of the stent extends via the open end and through the incision into the second artery;

. expanding the stent so that the hook elements hook fixedly into the second artery while the tail of the stent presses against an inner wall of the first artery so as to thus connect the first artery to the second artery.

IS. Method as claimed in claim 14, wherein the first artery is the LIMA, wherein the second artery is the LAD and wherein the step of positioning by means of a catheter with guide wire is performed via the LIMA.

Description:
Stent

The present invention relates to an accessory and method for realizing an atrial anastomosis.

Bypass operations are a regular occurrence in the field of cardiac surgery. When blood vessels become narrowed, for instance due to an unhealthy lifestyle or old age, the heart muscle receives less blood. This can result in different discomforts, and even a fatal myocardial infarction. In a bypass operation the narrowing is bridged making use of other pieces of vein, so that the heart muscle once again receives sufficient blood. The known method for performing a bypass operation comprises of performing a sternotomy, this being highly invasive for the patient. The recovery time following such an operation is also long, whereby it is a costly operation.

The invention is the result of a search for a less invasive way of connecting the coronary artery, also known as the left descending anterior artery (LAD), on the heart and the thoracic artery, also known as the left internal mammary artery ( LIMA) in the thorax in order to bridge a narrowing of the LAD.

It is an object of the invention to provide an accessory for connecting two arteries.

The invention provides for mis purpose a stent for connecting a first artery to a second artery, wherein the stent has a head and a tail, wherein the tail is elongate and has a diameter such that, in expanded state of the stent, the tail presses radially against an inner wall of the first artery, and wherein the head has a plurality of hook elements which in the expanded state of the stent extend radially outward so that the head is suitable to hook fixedly in the second artery via an incision.

In the above described definition of the problem the stent forms a connecting piece for connecting the LIMA and the LAD. More specifically, the head of the stent will be pre-inserted into the LIMA. This is possible for instance by means of a catheter with guide wire which is inserted into the LIMA via the groin area. Endoscopic tools can be introduced into the thoracic cavity via one or more incisions in the thorax. Via the endoscopic tools the surgeon can detach the LIMA from the thoracic wall and sever it so that the LIMA has an open end. The surgeon can also prepare the LAD via the endoscopic tools, and more specifically make an incision in the wall of the LAD at a position determined by the surgeon. This position is typically chosen to be directly behind a narrowing of the LAD which is being bridged. The LIMA can then be moved with its open end in the direction of the incision. The stent is pushed forward into the LIMA here until the head of the stent emerges from the open end of the LIMA, and wherein the head further protrudes via the incision into the LAD. Expanding of the stent in this position has the result that the hook elements, because they extend radially outward, hook fixedly into the LAD. The head of the stent is hereby prevented from moving out of the incision. The head of the stent thus hooks fixedly into the LAD via the incision. With further expanding of the stent the tail of the stent will press radially against an inner wall of the LIMA. Because the tail of the stent presses against the inner side of the LIMA, the LIMA is held fast by the stent. The stent will be fixed with its head in the LAD while the stent holds the LIMA fast with its tail. The stent hereby forms a connection between the LAD and the LIMA. This connection can be realized by a combination of catheterization and endoscopy, so that a sternotomy can be avoided. The stent according to the invention allows a LAD bypass to be realized here in minimally invasive manner.

During research and development of the stent for performing a LAD bypass in minimally invasive manner it was found that the stent has a wider field of application than just the above described surgery. More specifically, the stent can be applied for realizing an anastomosis in simple manner between two arteries. Anastomoses are conventionally carried out manually with a wire of about 0.2 mm. The manual realization of an anastomosis between two arteries can easily take ten minutes. Such anastomoses are often realized by surgeons at locations in the body which are difficult to access. Because of the limited freedom of movement and access to the location of the anastomosis the realization of a good anastomosis requires much skill, experience and knowledge. The tools used for the purpose are also expensive. The stent according to the invention considerably simplifies realization of an arterial anastomosis. The stent makes manual suturing wholly unnecessary and requires only a correct positioning and expanding of the stent. It is noted here that preparation of the arteries and positioning of one artery relative to another artery is also required when a manual anastomosis is realized.

Although the stent according to the invention was initially developed for positioning by means of a catheter with guide wire, in specific situations the stent can be positioned in alternative manner. For instance when open heart surgery is being performed wherein a coronary artery is being connected to the open heart, the stent can be inserted with its tail forward via the open heart in order to connect the coronary artery to the heart wall. The hook elements hook fixedly here to an inner side of the heart wall while the tail presses radially against an inner side of the coronary artery. In such a situation the stent can be placed without catheter.

The mechanism for expanding the stent can be formed in different ways. The stent is preferably resilient so that the stent has a natural tendency to expand. The stent is enveloped by a sheath here in order to bring the stent into its desired starting position, after which the sheath is removed in controlled manner so that the stent expands to an end position. A so-called balloon can alternatively be provided in the stent, which balloon is inflated when the stent is located in a desired position, wherein the inflation of the balloon controls expanding of the stent.

In the expanded state of the stent the tail preferably has a plurality of protrusions which function as barb to at least partially prevent axial movement of the tail relative to the inner wall. The plurality of protrusions more preferably extend at least partially radially outward from an outer surface of the tail in the expanded state of the stent. The plurality of protrusions more preferably extend at least partially in the direction of die head of the stent After the connection of the first artery to the second artery has been realized by means of the stent, it will always be the intention that blood will begin to flow again through the first and second arteries. Arteries function for the purpose of transporting oxygenated blood in the direction of the different body parts and organs. The internal pressure in arteries will hereby be increased by the heart Because of this internal pressure there will always be a resulting tendency of the first artery to move away from the second artery. By providing barbs in an outer surface of the tail, which barbs preferably extend radially outward and in the direction of the head of the stent, the barbs will grip into the inner wall of the first artery when this artery tends to move away from the second artery. The first artery is held fast by the barbs at a predetennined position relative to the tail of the stent so that a firm connection can be realized.

Each hook element preferably has a distal end which in the expanded state of the stent extends at least partially in the direction of the tail of the stent. In the expanded state of the stent the distal end of each hook element is preferably located at a distance from the tail in radial direction. The distance here is preferably at least 0.3 mm, more preferably at least 0.4 mm. Each hook element more preferably has a proximal end which in the expanded state of the stent extends substantially in line with the tail, and wherein each hook element comprises a curved hook segment which connects the proximal end to the distal end. Because the hook element is constructed in such a manner it is optimized to extend through the incision and to hook radially outward into the second artery behind the incision. Because the hooks are curved and the distal end of the hook extends in the direction of the tail, the hook elements will be able to pierce and thereby affix themselves in the inner wall of the second artery around the incision. Because the hook elements can pierce and thereby affix themselves, movement of the hook elements, for instance through sliding, is prevented. It is hereby possible through flow of the blood to build up an internal pressure in the second artery without the incision widening and beginning to leak. This is because the hook elements hook fixedly onto the inner wall of the second artery around the incision. Because the distal ends extend in the direction of the tail, the hook elements can pierce and thereby affix themselves in this inner wall. The hook elements hereby hold the inner wall of the second artery correctly positioned at the location of the incision. When the pressure in the first and second arteries is increased the head will also tend to move out of the incision. Because the head is held fast and has pierced and is thereby affixed around the incision, the movement of the head through the incision is prevented so that the stent remains correctly positioned.

The hook elements preferably comprise at least six hook elements distributed over a periphery of the stent. The hook elements more preferably comprise at least eight hook elements distributed over the periphery of the stent. A good distribution of pressure around the incision can be obtained by providing and distributing at least six, preferably at least eight hook elements over the periphery of the stent

The tail and the head preferably extend in the compressed state of the stent substantially as a cylinder of a substantially constant diameter so that the tail and head lie mutually in lie. This allows the stent to be moved in the first and second arteries so that the stent can be correctly positioned.

The stent is preferably manufactured from nitinol. Nitinol is a material known for its resilience and strength. Nitinol is also known for causing few or no undesirable reactions in the body.

The invention further relates to a set of a catheter and a stent, wherein the catheter comprises an expanding mechanism for the stent and wherein the catheter is further connected to a guide wire which is coupled to the expanding mechanism in order to control expanding of the stent. The stent can be positioned via the catheter and guide wire. Because an expanding mechanism for the stent is provided and coupled to the guide wire, the stent can be expanded in controlled manner once the stent has been brought into a correct position. Because the expanding mechanism is connected to the guide wire, expanding of the stent can be controlled and driven from outside the body, this further supporting the minimally invasive character.

The expanding mechanism is preferably formed by a sheath provided for the purpose of enveloping the stent in the compressed state and wherein the sheath is movable over the stent, wherein the movement is drivable via the guide wire. The stent is then preferably manufactured from a resilient material which tends to move into the expanded position. When the sheath is moved over the stent in order to slide off the stent, the stent will deploy and assume its expanded state and form.

The invention further relates to a method for connecting a first artery to a second artery, wherein the method comprises of:

- preparing the first artery so that the first artery has an open end which is movable;

- making an incision in a wall of the second artery;

- moving the open end of the first artery to the incision;

• positioning the stent of any of the claims 1-11 so that the tail of the stent extends in the first artery and so that the head of the stent extends via the open end and through the incision into the second artery ;

- expanding the stent so that the hook elements hook fixedly into the second artery while the tail of the stent presses against an inner wall of the first artery so as to thus connect the first artery to the second artery.

The first artery is preferably the LIMA, the second artery is the LAD and the step of positioning by means of a catheter with guide wire is performed via the LIMA. The invention will now be further described on the basis of an exemplary embodiment shown in the drawing.

In the drawing:

figure 1 shows a catheter with operating device and stent according to an embodiment of the invention;

figure 2 shows a detail of a catheter with a stent;

figure 3 shows a detail of a hook element of a stent according to an embodiment of the invention;

figure 4 shows a stent according to an embodiment of the invention; and

figure 5 shows a scenario of use of a stent according to an embodiment of the invention.

The same or similar elements are designated in the drawing with the same reference numerals.

In order to properly understand the context of the present invention and the field of application, the basic anatomy of blood vessels is elucidated. The aorta leaves the heart with a diameter of about 2.5 cm. The aorta branches many times in order to distribute the blood in the body. The first branches of the aorta are called arteries and carry oxygenated blood to the organs. In the organs the arteries branch further to arterioles, or small arteries. These carry the blood to the capillaries. Once the blood has been carried to the organs via the capillaries, which capillaries provide for metabolism of the blood, the deoxygenated blood flows to the venules, these being the smallest blood vessels in the venous system. The venous system is the system which carries deoxygenated blood back to the heart. The venules come together again to form small veins which in turn guide the blood to the medium-sized and large veins before it enters the vena cava, or the pulmonary veins. For functional reasons the wall of a vein is much thinner than the wall of an artery. An artery has more elastic fibres and smooth muscle tissue, whereby the arteries withstand the pressure changes in the blood flow. The stent according to the invention is particularly optimized to connect arteries. The stent is designed to withstand the high pressure and the changes in pressure typically occurring in arteries. In contrast to veins, arteries are elastic and relatively strong.

The LIMA, the left internal mammary artery, is a thoracic artery which runs over the chest about 1 cm from the sternum. The thoracic artery originates in the aorta and carries blood to the thorax. It branches and continues further to the pelvis where it also supplies blood. The LAD, the left descending anterior artery, is a coronary artery supplying the left side of the heart with blood.

Coronary narrowing can occur in the heart. That is, the coronary arteries are narrowed and less blood can flow therethrough. The consequence hereof is that the heart muscle can receive too little oxygen and cannot function and pump, or less so. If oxygen cannot reach the heart muscle, or can only do so with difficulty, it may die. This phenomenon is known as a myocardial infarction, and without surgical intervention can be fatal.

A disorder as described above can be solved by bypass surgery. This reroutes arteries to the correct location on the heart in order to thus bridge a constriction. Veins can be taken from the leg or arm, although the thoracic artery (LIMA) is preferably used. A vein is a less reliable candidate for a bypass because of its irregular structure. An artery has a thicker muscle wall, which makes it very elastic.

A bypass is literally a diversion of the blood flow. A diversion can be applied to any coronary artery. Particularly the connection between the LIMA and the LAD will be discussed in the context of this description. The description is however not limited to this connection, and will also comprise connections of other arteries.

The LIMA is located in the thoracic wall and the LAD lies on the left side of the heart. In the case of a bypass with these two arteries the surgeon typically cuts open the sternum by means of a sternotomy. Much preparation is required for such an operation. The patient must be made ready for placing on the heart-lung machine so that the heart and lungs can be stopped. Mainly with older patients, this forms a considerable risk. The LIMA is detached from the thorax and tested as to whether the blood flow is good. The surgeon has typically already found the location of the blockage in the LAD, for instance via angiography. The surgeon then positions the LIMA and the LAD and performs an anastomosis, also referred to as a cross-connection, in order to connect them. An anastomosis is traditionally performed with a thin wire of about 0.2 mm. Adhesive is applied over the connection in order to prevent leakage of blood. The adhesive typically disappears after a short time and allows the tissue to grow together. Once a good connection has been made, the patient is made ready to be removed from the heart-lung machine. The patient is also closed up again. The thorax is typically sutured with stainless steel wire. Such surgery is highly invasive and the patient will on average remain in hospital for ten days. Following the operation the patient must convalesce for up to two to three months.

An endoscopic procedure is minimally invasive for the patient Such a procedure typically requires multiple small incisions an average of 0.5 to 1 cm in size between the ribs. Installed through the incisions are tubes or ports through which the surgical instruments are placed. One entrance is typically used for the endoscope, a camera which the surgeon uses to follow the operation. Other entrances are typically used for instruments with which the operation is performed. The instruments can be easily replaced and accessories and materials can also pass through. A suturing body can thus be introduced via a port Such a port is also referred to in the field as a trocar.

Stents are known and are frequently applied in the medical world. A stent is formed by a metal or plastic tube having a compressed and an expanded state, hi the compressed state the stent is compact, with the purpose of making it possible to transport the stent through the body via a blood vessel. In the expanded state the stent takes on a form for fulfilling its function, for instance the removal of a blood vessel.

There are two types of stent, more specifically stents with two expanding mechanisms. A first type of stent is a self-deploying stent, also referred to as self-expandable stent. A second type of stent is a stent which is expanded by means of a balloon, also referred to as balloon-expandable stent. A balloon-expandable stent is placed prior to surgery on a balloon catheter. A self- expandable stent is preformed on the catheter in a sheath which ensures that the self-expandable stent remains compact until it reaches a location. In such an embodiment the stent is typically slid out of the sheath, or the sheath is slid away from the stent when the stent has been positioned in the body. Such stents are often manufactured from superelastic memory material such as nitinol, or from nickel or titanium. Such a stent typically consists of a metal structure pressed together on a crimper. Because of the metal structure, which is typically mesh-like, the wires can move toward each other easily to reduce the diameter from 2 to 3 mm to about 1 mm.

The stent is preferably manufactured from a cardiovascular biomaterial. The materials mostly used for a stent are steel, titanium, cobalt-chrome and nitinol. They have good biocompatible properties. Cardiovascular biomaterials are materials which can remain in the coronary arteries and can enhance their activity. Nitinol is an alloy of titanium and nickel. Because of its memory properties and its elasticity this material is a frequent choice for cardiovascular surgery. The memory properties of this material are related to the temperature. If a nitinol stent has its shape at about 30°, in a colder environment it can be compressed and will remain so until it returns to the temperature of 30°, at which it will then expand to its preformed shape. Nitinol can further withstand stress and deformation relatively well. In an artery a nitinol stent exerts a light outward force but withstands deformation with great force. Polymers such as polyamide (nylon) can alternatively be used in cardiovascular applications.

An adhesive can be used to improve a connection between two arteries. An example of adhesive is BioGlue from CryoLife, this being a biological surgical adhesive consisting of glutaraldehyde and concentrated bovine serum albumin.

Three stages can be distinguished in the method for placing the stent. The first stage is the transport stage in which the stent is transported through the arteries to the correct location. The second stage is the localization stage in which the correct place in the narrowed artery is localized so that the stent can be taken to this place. The third stage is the transformation stage wherein the stent is transformed from its compressed state.

The transport of the stent takes place by means of the catheter to which the stent is attached. The catheter is typically introduced via the groin area and transported via the femoral artery, the abdominal aorta, the aorta and, finally, the LAD. The skilled person will appreciate that the transport and the path covered depends on the desired location of use of the stent. The stent according to the invention provides a connecting system which can connect two arteries in a reliable manner and allows a blood flow between the two arteries. The stent can be introduced compactly into the body and reach a specific location which differs per patient. The stent is constructed so as to undergo a transformation whereby it adjusts to the arterial environment in order to carry out the functions described below.

When in an alternative method the stent is introduced into the body by means of endoscopic instruments, the transport step is performed in alternative manner and without catheter.

The stent can be manufactured by weaving nitinol wire or by laser cutting of a nitinol tube. The stent is preferably manufactured from a nitinol tube. Tests and simulations have been carried out to determine an optimal material thickness for the stent. These tests and simulations were done with a nitinol tube with a tube thickness of 0.1 mm, wherein the meshes were cut out so that a material width of 0.22 mm remained. Simulations demonstrated that, when the tube comes under a predetermined pressure, the yield point is exceeded and the material thus deforms plastically. The predetermined pressure is defined in accordance with the connection of the arteries, wherein the blood pressure and the blood pressure variation and the associated forces this causes on the stent material are taken into account. A second and third simulation were performed with respective tube thicknesses of 0.2 mm and 0.3 mm. It was found here that the tube with a tube thickness of 0.3 mm was very strong but probably too thick for use as stent. The hook elements would move too far outward, whereby the diameter would become too large and the interior space of the LIMA and/or LAD would be overfilled. It can be concluded herefrom that it is safe to manufacture a stent with a material thickness of 200 micrometres +/- 70 micrometres, preferably +/- SO micrometres, more preferably +/- 30 micrometres. A stent with such material thickness will not take away too much space for the blood flow and the elasticity of the LIMA allows extra space to be created by pushing on the wall.

Figure 1 shows a stent 1 mounted on a distal end of a catheter 7. Stent 1 is kept compact by a sheath 2. The figure illustrates how a guide wire 3 is used to guide catheter 7 to the desired location. Guide wire 3 can be introduced first into the artery, or can be introduced together with the catheter. An operating device 4 is provided at the proximal end of the catheter and guide wire 3. Operating device 4 comprises a moving element 5 and a basic element 6 which arc mutually connected by means of screw thread. Moving element 5 can be rotated relative to basic element 6 so that as a result of the rotation the moving element 5 displaces a predetermined and known distance relative to basic element 6. The movable part 5 is connected here to sheath 2 present around stent 1 such that, by turning moving element 5 relative to basic element 6, the sheath is removable in controlled manner from stent 1. The screw thread can for instance have a pitch of 1 mm so that with each rotation moving element 5 moves 1 mm relative to basic element 6.

Figure 2A shows a detail of a stent according to an embodiment of the invention in compressed position on the catheter. Figure 2B shows the same stent in a situation where the sheath has been moved partially to the rear, whereby the hook elements of the stent are expanded. Figure 2 A shows stent 1, sheath 2 and figure 2B also properly illustrates that catheter 7 has a basic body 8 which has in its outer surface a notch into which the stent fits in compressed state. The sheath is then pushed over the notch so that the stent can be transported in reliable manner through the body in compressed state.

Visual markings, for instance colour markings, are preferably arranged on catheter 7 in order to be able to follow and control positioning of the catheter via the endoscope. Radiopaque markings are more preferably also arranged in addition to visual markings such that the radiopaque markings can be visualized via the x-ray machine. A first marking is preferably provided here at the location of the hook elements of stent 1 and a second marking differing from the first marking is provided immediately behind the hook elements in compressed state of stent 1 , and a third marking is provided at the tail of the stent, as will be discussed in further detail below, wherein the third marking differs from the second marking. The first marking and the third marking can be the same or different The markings assist the surgeon in positioning of stent 1.

The transformation of the stent according to the invention preferably takes place in three steps, m the first step the stent is introduced via an incision into the second artery, after which the sheath is pushed over the hook elements so that the hook elements move outward. The second step in the transformation is further sliding the sheath 5 mm away from the tail so that the portion of the tail situated at the head with the hook elements folds open to substantially its final diameter. The hook elements hereby also come to lie in their final position. The stent is then typically pulled rearward so that the distal ends of the hook elements pierce and thereby affix themselves in the wall of the second artery. The wall of the second artery is hereby positioned fixedly at the location of the incision by the hook elements. In the third step the sheath can be wholly removed from the stent so that the whole tail of the stent presses against the inner wall of the first artery. Before the tail of the stent is fully expanded in this manner, the first artery is typically positioned over the stent, as closely as possible to the second artery, by means of endoscopic tools in order to optimize the connection.

Figure 3 shows a detail of a hook element 9 which forms part of the head of a stent 1 according to an embodiment of the invention. The figure further illustrates how hook element 9 connects to the tubular basic body of stent 1. The stent has a tail 11 and a head 12. The material thickness of the stent described in detail above is designated in the figure with reference numeral d. The hook elements extend over a distance in radial direction which is designated with reference numeral a. The diameter of the stent at the position of the head with the hook elements hereby increases by a distance equal to 2 x a. Hook elements 9 are curved so that the distal end of hook element 9 extends in the direction of the tail. The distal end of hook element 9 preferably extends over a distance b in the direction of the tail. Tests and simulations have indicated here that the thickness d is preferably 200 micrometres +/- SO micrometres, the distance a is preferably a minimum of 0.3 mm, more preferably a minimum of 0.4 mm, and is most preferably about 05 mm, and the distance b is preferably also a minimum of 0.3 mm, more preferably a minimum of 0.4 mm, and is most preferably about 0.5 mm.

A stent can be woven or manufactured via laser cutting. The laser-cut stents have a cross- section differing from the woven stents because they are manufactured from tube material while woven stents, as the name suggests, are manufactured from wire material wound along a tube of a predetermined size. The stent according to the invention is for instance made from tube material in order to guarantee a good processability and reliability of the stent

Following production of the stent the stent is preferably packed in sterile manner. This entails air, moisture and dirt not being able to reach the stent, so that the stent cannot be contaminated.

The cutting and shaping of the stent from the nitinol tube is preferably done such that the stent is cut in its expanded form. The hook elements are subsequently bent to their expanded shape by means of a mould, for instance a mechanical plug, and the stent will thus undergo a heat treatment. Owing to the heat treatment the stent will take on the compressed position of the hook elements as basic shape, or shape in expanded state. This is the shape to which the stent moves when external forces are removed and when the stent is at a predetermined temperature as described above, hi the same way barbs, which are discussed in more detail below, can be folded in the correct direction by means of a mould and the stent will undergo a heat treatment so that the direction of the barbs is fixed.

After shaping of the stent and performing of the heat treatments the stent is deformed so as to be brought into the compressed state. In the case of nitinol the stent is cooled so that the material can be deformed without losing its so-called memory. The stent can then be mounted on the catheter and covered with the sheath so that it is ready for further packaging.

Figure 4 shows an embodiment of a stent in two states. Figure 4A shows the embodiment in the compressed state, while figure 4B shows the stent in fully expanded state. Figure 4 also shows how the stent has a tail 11 and a head 12. Tail 11 and head 12 are preferably connected directly to each other and formed integrally as one whole. Stent 1 is provided with hook elements 9 at the location of head 12. In the compressed state of stent 1 hook elements 9 extend substantially parallel to the tubular form 10 of tail 11. In the expanded state of the stent hook elements 9 extend outward from tail 11 and are preferably curved so that the distal end of the barbs extends in the direction of tail 11. Figure 4 further shows how the tubular form 10 of tail 11 is provided with barbs 13. Barbs 13 extend radially from the surface of tail 11 in the expanded state. Barbs 13 farther extend in the direction of head 12 of stent 1. In unloaded state barbs 13 preferably have an angle relative to the outer surface of the tail of a maximum of 30°, preferably a maximum of 20°. The barbs extend over a distance of about 100 micrometres. Figure 4 further illustrates how the stent in a compressed state has a diameter V which is considerably smaller than the diameter W of the stent in expanded state.2 x V is preferably less than W.

Further indicated in figure 4 is where markings 18, 19 and 20 are preferably arranged. As described above, the markings can be visual markings and/or radiopaque markings. The head of stent 1 is preferably provided with a first marking 18, while a second marking is provided immediately behind the head. The tail of the stent can be further provided with a third marking 20. The third marking 20 can extend over the mil length of the tail or over a segment thereof.

A preferred scenario of use and method for the use of the stent according to the invention will be described with reference to figure 5. This scenario of use relates to bridging of the LAD making use of the LIMA. On the basis of this scenario of use the skilled person will clearly understand that other arteries can also be connected making use of the stent according to invention and via a method similar to the method described below.

The patient is fully anaesthetized and three incisions of about 1 cm are made. Endoscopic tools are carried through the incisions. These tools can always be interchanged during the operation. The surgeon detaches the LIMA from the thoracic wall via the endoscopic tools . The LIMA is cut through so that an open end results which is movable in the thoracic space. A portion of fat is preferably retained at the open end so that the surgeon can easily take hold of it later. When the LIMA has been detached, a bulldog clip can be placed thereon so that blood no longer flows therethrough.

The stent is transported to the LIMA making use of the catheter. This is typically carried out by the cardiologist who for this purpose makes use of x-ray images which show the blood vessels of the patient

The surgeon further prepares the LAD. For this purpose a needle is typically placed under the LAD, whereby the LAD is clamped shut. The passage of blood in the LAD is thus stopped. This action causes the LAD to swell and thicken and it becomes much more clearly visible on the heart. This simplifies the further actions performed thereon. The surgeon makes an incision of a predetermined length, for instance of about 2 to 2.5 mm, at a predetermined location in the outer surface of the LAD. In figure 5 the LAD is shown as the second artery 15, with the incision 16. The LIMA is shown as first artery 14 with the open end 17.

Once the LIMA and the LAD have been prepared in the above described manner, the surgeon can move the LIMA with its open end 17 to the incision 16 of the LAD. The surgeon can for this purpose take hold of the portion of fat. The cardiologist can then move the catheter carefully in the direction of the LAD 15 while the surgeon holds the LIMA 14 in place with an endoscopic clamp. By means of the visual markings on the catheter as described above the surgeon can see whether the catheter lies deeply enough, or not too deeply, in the LAD. Because the wall of the LAD is on average 1 mm thick, the first marking 18 preferably extends over a distance of 1 mm on the catheter. The skilled person will appreciate that the width of first marking 18 can be modified to the application.

The head of the stent is placed correctly in the LAD when the first marking is located in the LAD. The first marking is followed by a second marking. This line of between a half and one millimetre must still be visible to the surgeon. This then indicates that the location is correct. There is in addition a third marking 20 which indicates that the second marking has been passed when it is no longer visible. The cardiologist can him/herself also follow this on a screen. With radiopaque marking points he/she can see where he/she is located in the artery.

When the catheter has been correctly positioned, expanding of the stent can begin. The cardiologist can start the expansion by giving the operating device 4 a half-turn. He/she will rotate the moving element 5 to the rear and hold basic element 4 stably in the hand. When basic element 4 is rotated backward the sheath 2 of the catheter automatically moves with it Operating device 4 preferably has several pictograms 10 which indicate the position at which sheath 2 is located.

The cardiologist will first make a half-turn movement with operating device 4. When he/she sees the first pictogram, he/she knows that hook elements 9 of the stent have been expanded, which can also be verified on the screen. Once the first expansion step has been completed, the second one follows. The diameter of the stent now expands and pushes the wall of the LAD outward. The cardiologist must now hold operating device 4 in the same position and must then pull the catheter manually and gently in order to have hook elements 9 pierce the wall of the LAD. The surgeon preferably assists by using an atraumatic clamp, i.e. a clamp without teeth, which thereby causes no damage to the tissue. The surgeon pushes the clamp onto the LAD and helps the hook elements to pierce the tissue.

The hook elements must not pierce the tissue completely, but preferably pierce to about halfway through. The hook elements are therefore preferably half a millimetre in length. When the hook elements have pierced the tissue, the cardiologist can fully expand the stent by rotating moving element 5 of operating device 4 fully toward basic element 6. This corresponds to expansion of the whole stent. In order to help the stent to optimally retain its final position, the stent is provided with barbs on the outer side of the tail which, because of the elastic material nitinoL fold outward when the stent expands. The barbs pierce the wall of the LIMA and in this way anchor the stent. The barbs do not pass wholly through the tissue since they are only 300 micrometres long.

Once all the foregoing steps have been completed the stent is placed correctly. An adhesive can optionally be applied at the location of the connection of the arteries. The cardiologist and the surgeon can finally remove the instruments from the patient and close the wounds. On the basis of the above description the skilled person will appreciate that the stent can not only be applied for connecting the LAD and the LIMA, but that the stent is also suitable for connecting two arteries in a more general context. The field of application of the stent is therefore considerably wider than for connecting only the LAD and the LIMA.

The skilled person will appreciate on the basis of the above description that the invention can be embodied in different ways and on the basis of different principles. The invention is not limited to the above described embodiments. The above described embodiments and the figures are purely illustrative and serve only to increase understanding of the invention. The invention will not therefore be limited to me embodiments described herein, but is defined in the claims.

Key tolthe figures

1. stent

2. sheath

3. guide wire

4. operating device

5. moving element

6. basic element

7. catheter

8. catheter basic body

9. hook elements

10. tubular form

11. tail

12. head

13. barbs

14. first artery

15. second artery

16. incision in second artery

17. open end of first artery

18. first marking

19. second marking

20. third marking