DE20314392U1 - Flexible stent, for insertion into blood vessels and the like, has projecting bent anchors at the ends of the stent, in a structure with length stability at sites near the heart and in branch vessels - Google Patents

Abstract

The tubular stent (10), for insertion into blood vessels and the like, has a flexible mesh structure around its longitudinal axis. The stent wall has ring-shaped wall segments (11) in succession along the axis, with elastic sections (14,15), linked together by connection segments (12). The wall at the ends (20) of the stent has a flexible bent anchor (22), in one piece with the end wall elastic sections, forming a bridge over at least one wall section. The peaks (24) of the bent anchors are at a larger radial gap from the stent axis than the elastic wall sections.

Description

The invention relates to a stent for insertion into tubular hollow organs, especially the human body.

Generic stents and their use are known per se and are used for expansion and keeping open tubular hollow organs used in this. Such stents have a lattice or spiral structure that consists of wall segments. Between and within the wall segments become lattice openings formed which allow that this structure will grow into the tissue at its implantation site can. Such stents are known per se and for example in DE-A 197 46 88 or described in WO 03/063 733.

Stents have been tried to be designed in such a way that their position after implantation no longer change. For example, EP-A 0 778 011 describes the formation of thickened Stent ends, with the outside protruding, thickened ends after implantation of the tissue of the Overgrow the vessel wall which means a change in position, d. H. a shift along the tube axis is to be prevented. DE-A 197 46 882 describes a stent whose tubular lattice structure is formed from elastic wall segments that are elastic zigzag or V-shaped are formed and their pointed ends - in relation to the tube axis - in the radial direction outward are expanded and thus prevent stability even in severe vascular curvatures should.

The aim of the invention is one Stent, in particular to provide an expandable stent, where not only the positional stability is ensured, but also the especially in the area close to the heart, as well as in the area of moving and / or strong side branches can be used, without the risk of blocking blood flow to the branch.

This goal is achieved with those defined in the claims Characteristics achieved.

It was found that the aforementioned This will solve goals leave that with a stent of the generic type at the tubular stent end arcuate Anchoring elements can be arranged with the terminal wall segments forming wall elements in one piece are connected. In this case, preferably not adjacent elements connected in a bridge shape. The anchoring element has a larger radial one at its arch tip Distance to the stent axis as the terminal wall elements so that based on the diameter or lumen of the tubular stent is widened outwards, and the ends or tips of the arches themselves Anchor in the organ wall at the implantation site like a clamp or claw.

The anchoring elements are the same like the wall segments formed from webs and preferably have a larger width and / or thickness than the webs of the wall elements. The shape of the arcuate Anchoring elements can be both purely circular-arc shaped also be oval or oval-pointed. Preferably, the Bow, however, as a pointed arch V-shaped educated. In a very particularly preferred embodiment runs the Ogive in a slightly S-shaped Curve. The anchoring element at the arch tip is preferred reinforced and is in a particularly preferred embodiment in this area designed radio opaque. In this way, the attending doctor can closely monitor the stent's endpoints and location during the procedure. The ends or feet of the arch or V-shaped Anchoring elements are integrally connected to the wall elements of the stent, and are neither welded or glued to the stent using another connection technique appropriate.

In a special embodiment, the Arch of the anchoring element two non-adjacent wall elements a terminal, annular Wall segment. Usually lie at least between the bridged wall elements one, preferably two further elements. In the end area of the stent the wall segments are different than in the middle part directly without spring elements connected together so that this along the tube axis direction cannot be stretched or can only be stretched to a limited extent. That way the end area of the stent, despite flexibility, a necessary for anchoring, given sufficient strength.

The formation of the wall segments in the area between the stent ends can be arbitrary in the embodiment according to the invention be designed. Such flexible wall segments are known to the person skilled in the art known and for example in DE-A 100 50 940, DE-A 197 46 882 and described otherwise.

The stent according to the invention is preferably formed from elastic, annular wall segments which are arranged along a longitudinal axis and thus form a tubular lattice wall. Due to its elasticity, the stent can follow the movements of the hollow organ into which it is implanted. 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 along the continuous length web transferred and picked up by this.

A further development of the invention is characterized in that the annular wall segments wall elements comprise or are formed from a plurality of such elements. These wall elements are preferably spring elements which alternately under one of first spring elements and second spring elements formed angles are arranged to each other. This results in for the Wall segments have a zigzag elastic structure, creating a good, elastic spring action is achieved, which is also radial to the stent axis Expansion enables and the support effect the hollow organ causes.

The spring elements can in be approximately rectilinear. This straightforward training is in Regarding a projection onto an outer peripheral surface of the To understand stents.

Connect the connection segments expediently either only first or second spring elements with each other. The connecting segments themselves are opposite acting along the longitudinal axis of the stent Pushing and pulling forces not resilient and essentially rigid, d. H. that these together absorb the tensile and shear forces with the spring elements connected by them and a change in length prevent the stent. As a result, the connected first form or the second spring elements together with the connecting segments the continuous longitudinal web. For this purpose, the connection segments and the associated Spring elements can be arranged parallel to each other. This applies again in relation to the projection onto a peripheral surface of the stent. This ensures that the force is only applied along the longitudinal web and not a transverse component that has become an unwanted shortening or extension of the stent could. This closes enabling longitudinal expansion or contraction non linear course from how it z. B. by a zigzag or wavy Course of the longitudinal web arises.

An embodiment of the invention draws different from each other in a projection onto an outer circumferential surface parallel longitudinal webs from, which are arranged spaced apart in the circumferential direction. You can for example three or four longitudinal webs his. In this way, the wall segments become particularly effective positioned to each other, with a change in length at the same time of the stent is reliable is avoided.

It is also possible that the longitudinal web has a helical shape. For example then be the case when the longitudinal web is off the connecting segments and the first and second spring elements. this leads to to a particularly simple structure. Changes in length due to compressive stress or tensile stress or by compressing the stent anyway reliable avoided.

The connecting segments can also a larger material thickness or have width than the spring elements. Especially then when using a self-expanding stent with a laser from a tubular body small diameter is cut, there is a small Expenditure. In the first state with a small diameter they are Connection segments are then, for example, approximately S-shaped. In the second state with a larger diameter the connection segments then assign at least one component in parallel the longitudinal web on. The connection segments can for example, have twice the width of the spring elements. Thereby the result is a particularly simple sewing pattern.

The stent is preferably made in one piece. On 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 one Nickel-titanium alloy, as it is also sold under the name Nitinol will be used. Also polymers, like those in other areas of medicine used for implantation in the body suitable for producing the stent according to the invention. From a tubular body with Small diameter can then, for example, by means of laser radiation a suitable pattern for providing the spring elements and the connecting elements are cut out. Known Way this tubular body can then the expanded shape is imprinted become. The stent produced in this way is then in the state with a small size Diameter compressed and for example by means of a catheter inserted into a diseased blood vessel, so the stent can be in position by heating above the so-called conversion temperature are automatically brought back into the embossed shape.

As further materials for the stent also offer Stainless steel, plastic or so-called self-dissolving materials. In particular these self-dissolving Materials are beneficial when a stent is not permanent should be placed. If self-expanding stents are not used, can this at the desired one Position expanded, for example by means of a balloon catheter become.

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

The invention is based on the following Figures closer explained become. Show it:

1 a commercially available stent according to the prior art.

2 a stent with the invention Anchoring elements.

3 an enlarged partial view of a stent of 2 ,

4 shows a grid structure preferred for the stent according to the invention, as is used for the central wall region of the stent.

In the case of a stent according to the prior art as described in 1 is shown, sine-wave-shaped wall segments are sewn onto a cylindrical, fabric-like material. The wavy wall elements are connected to each other as a web only at the interface of the cylindrical fabric. At the upper end, the stent has a sewn-on, open wire segment, which is formed like the wavy wall segments, but in exactly the opposite direction, that is to say shifted by half a phase, without the open end segment touching the wall segments. For reinforcement, the upper edge of the fabric material is reinforced with a zigzag wire thread.

2 shows a stent according to the invention, the lattice-shaped tube wall is designed by means of a conventional cutting pattern, as described for example in DE-A 197 46 882. The tubular stent runs along an axis 26 and is at its ends 20 . 20 ' widened to the outside. This in 3 Enlarged end for better illustration 20 of the stent from 2 shows the structure of the wall segments 11 made of V-shaped wall elements 14 . 15 are constructed, the V-shaped elements being connected to one another at their tips and thus a circumferential around the longitudinal axis of the stent 26 Form a running zigzag line. The individual wall elements 14 . 15 are by spring elements connected to each other at their bridge tip 14 and 15 educated. In the area of the stent end are the ring-shaped wall segments lying one behind the other 11 on each of her wall elements 14 . 15 via connecting segments 12 connected to each other so that a diamond-shaped grid is created. At the end of this grid structure are the anchoring elements according to the invention 22 arranged so that they are with the distal tip of the wall elements 14 and 15 are connected in one piece. The curved or V-shaped webs of the elements 22 opposite the wall elements 14 . 15 widened. This can be easily produced using a simple cutting technique when trimming the stent. The bow tip 24 of the anchoring element 22 is provided with a radio-opaque material so that the position can be easily recognized by the doctor performing the examination on the X-ray image. As well as the 2 and 3 can be removed are the anchoring elements 22 bent outwards so that its tip 24 a greater distance from the stent axis 26 has than the wall or spring elements 14 . 15 with which they are connected. The anchoring elements particularly preferably have 22 an outward curvature, the radius of curvature increasing toward the tip of the arch. Because the anchoring elements 22 made of the same elastic material as the stent 10 themselves are formed, this form creates a clamping voltage, which the tips 24 presses into the surrounding organ and thus the entire stent 10 anchored.

4 now shows a preferred lattice structure as specified in DE-102 43 136 and in parallel applications. A stent 10 with such a pattern is used by laser radiation from a tube made of a suitable shape memory material, namely a memory metal, such as. B. Nitinol, cut out. As can be seen in the figure, the first spring elements are in a first state after the cutting pattern has been cut into the tube made of memory metal 14 and the second spring elements 15 arranged adjacent to each other. The first spring elements 14 and the adjacent second spring elements 15 are arranged parallel to each other in the cut, unexpanded state. The roughly S-shaped shape of the connecting segments can be clearly seen in the figure 12 , In addition, there are wall segments arranged adjacent to one another 11 each offset by an offset, which is the thickness of the first spring element 14 and the second spring element 15 equivalent. In this way, a first spring element is in the first state 14 of a wall segment 11 at its ends using connecting elements 12 with a first spring element offset by the offset 14 of the neighboring wall segments 11 connected. After cutting the pattern in a tubular blank z. B. from memory metal, the stent thus produced is expanded into a second state, which has a larger diameter than the first state. This second condition becomes the stent 10 then imprinted in a known manner. The stent prepared in this way is prepared for implantation by means of a catheter 10 then compressed into a small diameter state. After the desired positioning, the stent 10 then be expanded again by heating above the so-called conversion temperature into the impressed form of the second state. But it is also possible to use the stent 10 expand using a balloon catheter.

10

stent

11

wall segment

12

connecting element

13

longitudinal web

14

first spring element

15

second spring element

16

Krafteinleitrichtung

17

stent

18

longitudinal web

20

tube end

22

anchoring element

24

bow lace

26

tube axis

Claims (12)

Stent ( 10 ) with a longitudinal, flexible tube axis ( 26 ) running tubular wall formed from a flexible lattice structure with tube ends lying on opposite axis ends ( 20 ), whereby the wall consists of annular wall segments ( 11 ) is formed, which are lined up along the axis and which are connected by means of connecting segments ( 12 ) are connected to each other and the annular wall segments ( 11 ) Wall elements ( 14 . 15 ) with an elastic structure, characterized in that the wall on at least one tube end ( 20 . 20 ' ) a flexible, arch-shaped anchoring element ( 22 ) which has at least two terminal wall elements ( 14 . 15 . 14 ' . 15 ' ) is connected in one piece and at least one elastic wall element ( 14 . 15 ) bridges and that the arched anchoring element ( 22 ) at its bow tip ( 24 ) a greater radial distance from the tube axis ( 26 ) than the terminal wall elements ( 14 . 15 ). Stent according to claim 1, characterized in that the arch of the anchoring element ( 22 ) Is V-shaped. Stent according to claim 1, characterized in that the arch of the anchoring element ( 22 ) has a larger material width than the wall elements ( 14 . 15 ). Stent according to claim 1, characterized in that the anchoring element has at least two wall elements ( 14 . 15 ) bridges. Stent according to claim 1, characterized in that it has at least three anchoring elements ( 22 ) having. Stent according to claim 1, characterized in that the bow tip ( 24 ) has an X-ray opaque area. Stent according to one of the preceding claims, characterized in that the arcuate anchoring element ( 22 ) to its top ( 24 ) is curved to the outside in a curve. Stent according to claim 7, characterized in that the curvature to the arch tip ( 24 ) increases. Stent according to one of the preceding claims, characterized in that the wall elements ( 14 . 15 ) of the wall segments ( 11 ) of the opposite tube end ( 20 ) radiopaque areas ( 24 ) exhibit. Stent according to one of the preceding claims, characterized in that the opposite tube end ( 20 ' ) related to the tube axis ( 26 ) is expanded radially and has a larger diameter than the center of the stent. Stent according to one of the preceding claims, characterized in that the widening along the tube axis ( 26 ) on at least two ring-shaped wall segments ( 11 ) begins before the end. Stent according to one of the preceding claims, characterized in that at the tube end ( 20 . 20 ' ) on at least the terminal wall segment and the next wall segment lying axially in front of it ( 11 ) each wall element ( 14 . 15 ) of the terminal segment ( 11 ) with its element axially in front ( 14 . 15 ) of the next segment ( 11 ) by means of a connecting segment ( 12 ) connected is.