WO2005028014A1

WO2005028014A1 - Device for being introduced into body organs and having a marker element for controlling the position thereof

Info

Publication number: WO2005028014A1
Application number: PCT/DE2004/002072
Authority: WO
Inventors: Johannes Jung
Original assignee: Campus Gmbh & Co.Kg
Priority date: 2003-09-16
Filing date: 2004-09-16
Publication date: 2005-03-31
Also published as: DE20314393U1; DE10342758A1

Abstract

The invention relates to a device for being introduced into hollow organs of an especially living body, comprising an element having a tubular radially elastic wall and a radio-opaque marker element for determining the position of the device inside the body. The invention is characterized in that the radio-opaque marker element is disposed circumferentially around the elastic or expandable tubular wall in a spiraling manner. The device according to the invention is preferably a catheter or stent.

Description

DEVICE FOR IMPLEMENTATION IN BODY ORGANS WITH MARKING OF POSITION CONTROL

DESCRIPTION:

The present invention relates to a device for insertion into particularly tubular hollow organs of the body, such as catheters, especially antiography catheters and stents, which contain detectable markings in the body for position control.

The introduction of devices into a body or into body parts for minimally invasive diagnosis, examination and treatment of pathological and / or abnormal conditions of body parts is becoming increasingly important. For example, hollow organs, in particular tubular hollow organs such as blood vessels, esophagus, biliary tract, intestine or ureter, are examined by means of a catheter to be inserted into the hollow organ and, if necessary, constrictions after dilation are eliminated by introducing a supporting stent. The course of such a catheter examination or the introduction of a vascular support such as a stent is regularly checked by X-ray. To eliminate vasoconstrictions, so-called stenoses, a catheter is usually inserted into the corresponding hollow organ, at the end of which an inflatable, balloon-like dilation element is arranged. This inflatable dilation element is inflated when it has reached the area of the stenosis, as a result of which the narrowed area is expanded to a desired lumen or a desired diameter. After such a balloon dilation, a vascular support is then inserted into the corresponding hollow organ, or possibly also simultaneously with the dilation. The procedure is usually such that the stent, that is, a so-called stent, is inserted into the region or section of the constriction in a compressed, unexpanded state and is expanded radially to its longitudinal axis at this point. This can be done by means of the inflation or insulphonation of the balloon already mentioned, as well as by so-called shape memory materials such as, for example, nickel-titanium alloys with temperature-dependent shape behavior, as is available under the trade name Nitinol ^R. This procedure is known per se and a large number of catheters and stents have already been described. A problem with this procedure is that both such vascular supports and the catheters are made of materials that are difficult to display on the X-ray screen. It is therefore difficult for the attending physician to determine the respective position of the stent or catheter. For this reason, a large number of radiopaque markings have already been proposed. For example, EP-A 0 679 372 describes radiopaque markers which are arranged in particular at the end of the stent. In EP-A 0 800 800, detection elements with a larger width and a flat material area are proposed, so that these elements can be recognized more clearly on the x-ray screen than the individual, thin, elongated boundary or wall elements of a stent. Furthermore, EP-A 0709068 describes terminal protrusion elements which contain so much material that they are visible in the X-ray screen.

DE-A 101 52 511 describes a vascular catheter with a three-dimensional orientation option, the catheter consisting of two parts, namely a shaft with little radiopaque shade and a strongly radiopaque end part with a tip, and the end part and shaft being at an angle greater or form less than 90 ° so that the contact surface is asymmetrical to the catheter axis. In this way, the surgeon can determine from the position of the bevel of the connection point between the end part and the shaft whether the catheter tip is directed forwards, to the side or to the rear. Unfortunately, information about the degree of dilation is not possible with this procedure.

Although the approaches proposed in the prior art make it possible for a doctor to show the respective position of the catheter and / or stent, these markings are not suitable for giving an operating doctor information about whether a balloon catheter has expanded sufficiently to accommodate the To expand the lumen to the desired diameter. The same applies also for the expanding stents. The markings of the prior art are only suitable for showing the position of the stent or catheter in the vessel, namely the beginning and the end, but not whether the stent has expanded sufficiently over its entire length and provides the desired lumen required can.

The aim of the invention is therefore to provide a marking, in particular of medical devices, which not only indicate the position to an operating doctor when inserted into a body, but also whether a corresponding expansion, be it a dilatation balloon or a stent, itself has actually expanded in the desired manner and to the extent desired, or whether these are still in their original, not or not fully dilated form.

It often happens that when inserting or inserting a stent, especially a stent with a shape memory such as. B. a nitinol stent, this does not expand sufficiently. It is often not possible to post-dilate the stent immediately. However, the stent often expands on its own after some time in the patient. By means of the radiopaque marking according to the invention, it is therefore possible in a later control examination to determine in a simple manner, by means of an x-ray, whether the stent is dilated in the desired manner or whether the stent has to be expanded in a further operation by means of balloon dilatation or if necessary removed again must become . This goal is achieved by the features defined in the claims.

According to the invention, it is proposed to provide the jacket or the wall of a stent or catheter, in particular a balloon, in a spiral or helix shape with radiopaque markings. This procedure makes it possible to determine the degree of expansion over the entire length of the tubular wall, regardless of the direction from which a doctor looks at the catheter or stent by X-ray. In addition, no body parts lying in front of and / or behind the inserted device are covered with this procedure and can therefore still be represented in the X-ray image. In the case of stents in particular, it is possible in this way to check the degree of vascular opening or to determine the expansion state of the stents used, even at later times.

The tubular or balloon-shaped wall of the device according to the invention is expandable. It can be plastically deformable either permanently or reversibly, as is the case, for example, in the case of balloon expansions, in particular also balloon-expandable stents, or it can also be elastic or superelastic, as is the case, for example, in the case of self-expanding stents or dilatation balloons. In many cases, however, so-called shape memory materials have been found. Such materials are nickel-titanium alloys as are available under the trade name Nitinol. Since both the balloon catheter and the stents are often used in vascular curvatures find or have to pass through it, the tubular device according to the invention can be elastically bent along its longitudinal axis of the tube.

The radiopaque marking can run around the cylindrical wall in a thread-like form. It is preferably designed as a thin, X-ray opaque thread. However, it is particularly preferred to apply the X-ray-opaque marking in the form of small-area punctiform areas along a spiral or helical line around the entire cylindrical jacket in a manner similar to a string of pearls. This can be done, for example, by using opaque X-ray material in recesses or recesses in the wall. In principle, it is also possible to place them on the wall from the outside or inside. In a particularly preferred embodiment, the X-ray opaque area with the little X-ray opaque wall material forms a smooth inner and / or outer surface. According to the invention, a single, spiral-shaped marking is sufficient, but it is of course also possible to arrange two or more radiopaque, spiral-shaped markings.

X-ray opaque material is known per se. Commonly used x-ray opaque materials according to the invention are gold, platinum, silver and / or tantalum.

The wall of the device according to the invention is usually tubular and consists of interconnected wall segments. The individual wall segments are connected to one another via connecting elements. The connecting elements are preferably flexible. tet. In a particularly preferred embodiment according to the invention, the X-ray-opaque areas are arranged in the connecting elements.

If the device according to the invention is a stent, it preferably has a grid-shaped tube or hollow cylinder in its basic structure, which runs around or along a central axis. The stent itself is flexible and bendable along this axis so that it can overcome turns, bends or branches when inserted into a body organ. The tubular lattice structure is formed by a wall provided with openings, the wall containing elastic ring-shaped wall segments running around the axis, which are connected to one another via connecting segments. The ring-shaped wall segments themselves are made up of wall elements which are combined to form a ring surrounding the axis. The ring-shaped wall segments are lined up along the central axis, the individual segments being connected to one another by connecting segments. Individual ring-shaped wall segments contain spring elements which give the wall segment the desired elasticity in order to allow the stent to expand radially to the central, bendable axis, the diameter of the inner tube lumen or the hollow cylinder formed by the wall being increased. In this way, the wall segments develop the desired elastic support effect on the hollow organ. The wall segments are preferably formed entirely from adjacent spring elements or webs lying in the wall plane, which form a ring around the stent axis in a V-shape or zigzag shape. The wall segments are preferably constructed from the spring elements. The spring elements are usually flexible webs which are connected to one another at their ends in a V-shape via connecting points or connecting elements. The invention is now characterized by a special configuration of these flexible webs or spring elements.

According to the invention, these spring bars can be designed to be straight or linear and / or wave-shaped, as a result of which the forces acting on the connection points during expansion and bending along the tube or stent axis are greatly reduced. The wavy structure expediently runs in the wall surface. In its simplest form, this structure is formed from a simple wave, i.e. H. from a wave valley and a wave crest. The curved wave shape has at least one turning point. Of course, according to the invention it is possible to form the spring elements from a plurality of wavy curves running one behind the other. According to the invention, it is also possible to have the wave-shaped structure run in a zigzag structure instead of being sinusoidal.

In a further embodiment according to the invention, the spring elements are designed in such a way that the angle formed between them on the V-shaped connecting segments is concave with respect to the interior of the angle, that is to say that the angle formed tangentially by two adjacent spring elements decreases and becomes smaller towards the spring web end or the spring connecting element becomes. This means that in relation to the point of connection of the springs, a symmetrical structure is formed that corresponds to that of the Greek see letter v corresponds in symmetrical spelling.

In a development of the invention, the individual wall segments are connected to one another by means of a continuous longitudinal web. In a special embodiment, the longitudinal web is linearly continuous and can thus absorb compressive or tensile stresses in the longitudinal direction without causing a change in the length of the stent. Similarly, contracting, ie compressing the individual wall segments, likewise does not result in a change in the length of the stent, since the tensile or compressive stresses that may occur are transmitted to and taken up by the continuous longitudinal web.

A further development of the invention is characterized in that the annular wall segments comprise wall elements or are formed from a plurality of such elements. These wall elements are preferably spring elements which are arranged alternately to one another at an angle formed by first spring elements and second spring elements. This results in a zigzag-like elastic structure for the wall segments, as a result of which a good, elastic spring action is achieved, which also enables radial expansion to the stent axis and brings about the support action on the hollow organ.

The connecting segments expediently connect either only first or second spring elements to one another. The connecting segments themselves are not shear and tensile forces acting along the longitudinal axis of the stent elastic and essentially rigid, that is to say that these, together with the spring elements connected by them, absorb these tensile and pushing forces and prevent a change in length of the stent. As a result, the respectively connected first and second spring elements together with the connecting segments form the continuous longitudinal web. For this purpose, the connecting segments and the spring elements connected to them should each be arranged parallel to one another. This again applies to the projection onto a circumferential surface of the stent. This ensures that the force is applied only along the longitudinal web and has no transverse component that could lead to an undesired shortening or lengthening of the stent. This precludes a longitudinal expansion or contraction enabling a non-linear course, as it is e.g. B. arises from a zigzag or wavy course of the longitudinal web.

One embodiment of the invention is characterized by a plurality of longitudinal webs which are parallel to one another in a projection onto an outer circumferential surface and are spaced apart from one another in the circumferential direction. This can be, for example, three or four longitudinal webs. In this way, the wall segments are positioned particularly effectively with respect to one another, while at the same time reliably preventing a change in the length of the stent.

It is also possible for the longitudinal web to have a helical shape. This can be the case, for example, if the longitudinal web consists of the connecting segments and the first or second spring elements. This leads to a particularly simple structure. Längenän- Changes due to compressive or tensile stress or by compressing the stent are nevertheless reliably avoided.

The connecting segments and the connecting elements can also have a greater material thickness or width than the spring elements. In particular, if a self-expanding stent is cut from a tubular body with a small diameter by means of a laser, there is little effort. In the first state with a small diameter, the connecting segments are then, for example, approximately S-shaped. In the second state with a larger diameter, the connecting segments then have at least one component parallel to the longitudinal web. The connecting segments can for example have twice the width of the spring elements. This results in a particularly simple sewing pattern.

The stent is preferably made in one piece. In this way, a stable construction results without unnecessary edges or predetermined breaking points.

A shape memory material, such as a so-called memory metal, namely a nickel-titanium alloy, as is also sold under the name Nitinol, can be used as the material for the stent. Polymers, such as those used in other areas of medicine for implantation in the body, are also suitable for producing the stent according to the invention. A suitable cutting pattern can then be made from a tubular body with a small diameter, for example by means of laser radiation, in order to provide the spring elements and the connections. segments are cut out. The expanded shape can then be impressed on this tubular body in a known manner. If the stent produced in this way is then compressed into the state with a small diameter and, for example, inserted into a diseased blood vessel by means of a catheter, the stent can be automatically brought back into the impressed shape by heating it above the so-called conversion temperature.

Stainless steel, plastic or so-called self-dissolving materials are also suitable as further materials for the stent. These self-dissolving materials are particularly advantageous if a stent should not be permanently inserted. If no self-expanding stents are used, they can be expanded at the desired position, for example using a balloon catheter.

The surface of the stent should preferably be processed, in particular refined, smoothed and / or polished. This results in a smooth and body-friendly surface.

This wave-shaped design of the spring bars according to the invention is preferably such that it does not lead to any significant amount of longitudinal elasticity, i. H. that the webs change their length along the longitudinal axis of the stent in the event of tension and compression.

The device according to the invention is preferably cut along the wall by means of a laser beam. given cutting pattern or cutting lines. In this way, interconnected wall segments are formed, which are preferably connected by means of flexible connecting elements and whose spaces define the lattice openings. The X-ray opaque materials are inserted into the wall surface before and after cutting, preferably in such a way that they form a smooth plane with the inner and outer wall surface. Such a pattern is shown, for example, in the attached FIG. 1.

For a better understanding, the invention is explained in more detail using the following figure.

1 shows a device according to the invention in the form of an unexpanded cut stent. The tubular stent is shown in FIG. 1 in a cut shape projected into a plane. The röntgenopa- ^'ken marks are displayed in black and extend on the cylindrical or tubular stent wall in a helical or spiral helical line. If such a helical line is imaged by X-rays, the image of a sinusoidal wave with constant amplitude is created. If the amplitude is reduced at certain points, this indicates that at this point the stent or balloon has not expanded as much as the adjacent marked areas or wall segments.

Claims

DEVICE FOR INSERTING IN BODY ORGANS WITH MARKING OF THE POSITION CONTROL PATENT REQUIREMENTS:

1. Device for insertion into hollow organs of a body, comprising an element with a radially elastic tubular wall and an X-ray-opaque area for determining the position of the device in the body, characterized in that the X-ray-opaque area is arranged circumferentially spirally around the tubular wall.

2. Device according to claim 1, characterized in that it is a catheter.

3. Device according to one of the preceding claims, characterized in that it is a balloon catheter.

4. Device according to one of the preceding claims, characterized in that it is an expandable stent made of a tubular wall running around a longitudinal axis, which is formed from flexible wall segments defining interconnected lattice openings and containing radiopaque areas, the tubular wall being one first, unexpanded state with a first small lumen radius and a two- ten, expanded, with a second larger lumen radius.

5. Device according to one of the preceding claims, characterized in that it contains at least two spirally parallel markings.

6. Device according to one of the preceding claims, characterized in that the radiopaque markings are point-shaped.

7. Device according to one of the preceding claims, characterized in that the X-ray opaque marking is a spiral thread.

8. Device according to one of the preceding claims, characterized in that the radio-opaque markings are angeord- in the connecting elements of the wall elements net ^'.

9. Device according to one of the preceding claims, characterized in that the X-ray opaque material is gold, platinum, silver and / or tantalum.

10. Device according to one of the preceding claims, characterized in that it is formed from a biodegradable material and / or a shape memory material.