DE102004045994A1 - Stent for implantation in or around a hollow organ with marker elements made from a radiopaque material - Google Patents

Abstract

A stent (10) for implantation in or around a hollow organ is described which has marker elements (19) of a radiopaque material. The stent comprises a tubular lattice wall (12) extending around a longitudinal axis (11) of elastic wall segments (13) circumferentially arranged longitudinally along the longitudinal axis (11) and interconnected by connecting elements (14) having opposite axis ends Tube ends (15), the wall segments (13) comprising spring elements (16) with an elastic structure, the wall segments further comprising receiving elements (17) connected to the spring elements (15), and wherein the receiving elements (17) have recesses ( 18), in which marker elements (19) are arranged from a radiopaque material. The stent is characterized in that the receiving elements (17) are curved in a circular arc around the longitudinal axis (11) of the stent (10), the recesses (18) have tapering diameters in the direction of the longitudinal axis (11) and the radiopaque marker elements (19 ) radioconically formed and radially to the longitudinal axis (11) in the recesses (18) of the receiving elements (17) are arranged.

Description

The The invention relates to a stent for implantation in or around a hollow organ with marker elements from a radiopaque Material of the type mentioned in the preamble of claim 1, as well as a method for its production.

stents become common in tubular hollow organs used to expand or keep it open. they form a tubular structure out in their tube interior the flow of body fluids or other physiological substances, such as. B. allows food, where the outside of the tube the surrounding hollow organ rests and this supports. They usually have a lattice or spiral Structure consisting of wall segments. Between and within the wall segments are grid openings trained, which make it possible that this structure grow into the tissue at its implantation site can.

Such Stents are known per se and, for example, in DE-A 197 46 882 or described in WO 03/063 733.

In most cases Stents are mounted on a balloon catheter, which is then placed in the introduced to be treated hollow organ. This can happen e.g. to treat a coronary artery affected by a stenosis. On the spot, the balloon catheter is then dilated, on the one hand the plaques that cause the stenosis to or through the vessel wall too to press and thereby eliminate the stenosis and on the other hand the through to place the dilatation of the balloon catheter unfolded stent, the then for that ensures that the hollow organ retains its clear width.

In other cases self-expanding stents are used which are in a first state with small diameter introduced into the hollow organ and then in place in a second state with bigger ones Expand diameter by an intrinsic spring force by itself or to be actively expanded. For this come in particular stents in question, made of a shape memory material are made.

In both cases finds the placement of the stent under radiographic control instead of. As the usual for the Stents used metal alloys have only a low radiopacity, For this purpose, it is helpful to provide the stent with additional materials, the one higher Have radiopacity.

From the EP 95302708 It is known to coat the ends of the stent with a few micrometers thick layer of radiopaque material (gold, platinum). This type of marking is complex and expensive. Moreover, there is a risk that parts of the coating will come off over time, so that the position of the stent within the hollow organ can no longer be determined accurately. In addition, the coating can lead to an increase in the stiffness of the stent, so that, for example, the dilation of the stent in the hollow organ to be treated can be impaired.

Out WO 9733534 is known, rivet-shaped marker elements of radiopaque Use material in loop-shaped receptacles the latticed Wall structure of the stent form-fitting fitted become. This type of design entails the risk that the rivet due to mechanical stress or corrosion their form-fitting loses, z. B. in which the rivet head breaks, and then dissolves, into Lumen of the stent escapes and enters the hollow organ where it Serious complications, such as cause the occlusion of a blood vessel can.

The Object of the present invention is to provide a stent Marker elements from a radiopaque Provide material that has a permanent localizability within the hollow organ ensures and its elasticity is not affected by the marker elements. Furthermore should be guaranteed be that the marker elements under any circumstances escape into the lumen of the stent and can get into the hollow organ.

These The object is achieved with the features of claim 1.

According to the invention is a stent of the generic type provided, which extends around a longitudinal axis extending tubular grid wall comprising elastic, in particular radially elastic wall segments, the circumferential along the longitudinal axis one behind the other arranged and over Connecting elements are interconnected. The stent points on opposite axial ends lying tube ends. The wall segments have spring elements with an elastic structure and receiving elements, the are connected to the spring elements. The receiving elements have wells or recesses in the form of cavities, gaps, holes and / or recesses on, in which marker elements are arranged from a radiopaque material are.

The recording elements can be compared be formed widened flat to the spring elements. The recesses may be configured, for example, in the form of recesses.

Of the Stent according to the invention is characterized in that the recesses in the direction of longitudinal axis tapering, especially conically rejuvenating, Have cross-sectional areas and the radiopaque Marker elements are conical and radial to the longitudinal Axle are arranged in the recesses of the receiving elements. The marker elements are therefore similar the capstone of a Roman vault arranged in the receiving elements.

On this way is guaranteed that the marker elements are not in the tapering direction of the cross sectional areas of the Can move recesses, even if they break or corrode, and therefore under none circumstances can escape into the lumen of the stent. The marker elements can become at most contrary to the direction of rejuvenation the cross-sectional areas replace the recesses, ie towards the wall of the hollow organ, where they do no harm Serve.

In A preferred embodiment of the invention provides that the recesses and the marker elements have round cross-sections, and the marker elements are formed radially conically in the form of truncated cones are. Under the term "round Cross sections "should doing circular, oval and elliptoid cross sections are understood.

In a further preferred embodiment of the invention is provided that the recesses and the marker elements are substantially rectangular Have cross sections, and the marker elements conical in the form of truncated pyramids are formed. The term "substantially rectangular Cross sections "should thereby also such cross sections fall, which go back to rectangles, whose Corners were rounded off.

In a development of the invention are the marker elements on their the longitudinal axis facing away from the receiving elements welded and on this way permanently locked in the recesses. Preferably are doing in the transition area set welding points between the receiving elements and the marker elements, for what For example, a laser can be used.

In a further preferred embodiment of the invention is provided that the receiving elements are arranged at the tube ends of the stent. This ensures that that the ends of the stent in the radiograph while the catheter surgery or on the occasion a check-up examination can be safely addressed and so the correct position of the stent can be controlled.

In addition, can be provided that even in the area between the tube ends Receiving elements are arranged. In particular, these can be on a grid wall be arranged in a helical circumferential line. To this Way can be in the x-ray Determine if the stent is in place and evenly has been unfolded correctly.

In A particularly preferred embodiment of the invention is provided, that the receiving elements at the tube ends of the stent circumferential are arranged, so a terminal, at the indoor or outside Forming the hollow organ fitting garland radiopaque markers. In a further inventive preferred Embodiment are the receiving elements transverse to their longitudinal direction circular arc curved around the 1πitudinale axis of the stent.

In embodiments according to the invention, in which the receiving elements are arranged at the tube ends, can the support effect at the tube ends impaired be less supportive here Material available stands as in the area between the tube ends. The length of the effectively supportive Be rich of the stent falls therefore usually smaller than the absolute length of the Stents itself is.

In a further embodiment of the invention is therefore provided that at the tube ends additionally terminal to the receiving elements Spring elements are arranged circumferentially. These terminal spring elements can be wider than the already described spring elements in the area between the tube ends.

Prefers is provided that the receiving elements and the terminal spring elements alternately circumferentially arranged.

advantage In this embodiment, the tube ends of the stent unfolded Condition better support to exercise on the vessel wall, what As a consequence, the length of action of the stent, ie the area, in the e.g. a restenosis can be effectively prevented is significantly larger.

These types of embodiment are particularly advantageous in the case of stenoses in the region of vessel branches, for example in the case of blood vessels. Since the effective supporting surface of such a designed stent only at the actual tube end ends, it is ensured that the stent can be brought up directly to the junction, without the risk that widened receiving elements protrude into the bloodstream of the branching vessel and there to turbulence of the blood flow and thus lead to clumping of the blood cells.

In Particularly preferably, it is provided that the terminal spring elements and the receiving elements are designed and / or arranged such that in the direction of the tube or Stent ends of the elements have a circular, transverse To describe the longitudinal axis arranged Umfangsli never, ie almost flush are arranged. This arrangement has the particular advantage that when placing the stent, i. when moving forward with the help of a Catheter, the pressure is more uniform the entire end peripheral area of the stent is distributed. That means when dismissing or pushing forward of the stent from the catheter, the forces occurring do not work only on the x-ray markers, but especially on the terminal, finger-like spring elements, whereby the occurring resistance is better distributed and the Marker elements are relieved. That way, the danger that a welded marker peels off or even breaks, greatly reduced. This also reduces the risk that individual terminal elements bend and, if necessary, cut into the vessel wall. The terminal ones Spring elements are preferably wider, in particular at least twice as wide, designed as the wall segments.

Besides that is thereby ensuring that such a thing designed stent to flush final tube end the full support effect can unfold. The advantages outlined above are still there stronger to carry.

In a development of the invention form the connecting elements and the spring elements at least one continuous longitudinal web, in the longitudinal direction of the stent and the at least one component in the axial direction for receiving a compressive or tensile stress in the longitudinal direction. Corresponding this embodiment can also several longitudinal webs be educated. In this way the wall segments become special effectively positioned to each other, with a change in length at the same time the stent reliable is avoided.

Prefers It is provided that the longitudinal web or the longitudinal webs a helical wall has the shape surrounding the grid wall exhibit. This type of configuration can be achieved by cutting, in particular laser and / or water jet cutting, from a hollow cylinder especially easy to make. In addition, so length changes due to compressive or tensile stresses or by compression of the Stents within the scope of the intended use personnel reliably avoided.

In Particularly preferably, it is provided that the connecting elements are formed widened flat compared to the spring elements. This type of configuration can also be achieved by laser cutting easy to make. In the state before deployment of the stent are the connecting elements then formed, for example, slightly S-shaped. In the unfolded state with larger diameter then have the connecting elements at least one parallel to longitudinal web arranged component and support this in the previously described Effect.

Especially Preferably, it is provided that the connecting elements double Have width of the spring elements. This results in a special simple pattern. Usually, however, not necessarily, the connectors are shorter than the spring elements and expediently have a length of a maximum of 3/4, preferably a maximum of 2/3 of the length of a spring element. Particularly preferred are lengths of 1/2 or less of the length a spring element.

Basically everyone has to materials used in a stent may be biocompatible. Put it However, there are other specific requirements for the various in the stent according to the invention used materials.

Prefers exist the radiopaque Marker elements of the stent according to the invention from a material that is selected is from the group consisting of gold, platinum, silver, tantalum, with Barium sulphate doped plastic, plastic doped with bismuth trioxide. It can however, as well as other radiopaque Materials are used.

The Spring, connecting and / or receiving elements of the stent according to the invention most preferably consist of a shape memory material.

Especially Preferably, the shape memory materials to be used are selected from the group made of nickel-titanium alloys and copper-zinc-aluminum alloys selected. As especially suitable the nickel-titanium alloy Nitinol has been found.

From a hollow cylinder made of such material can, for example by means of a cutting technique, such. B. by laser or water jet, a substantially consisting of spring elements, connecting elements and receiving elements existing stent are cut out, which can then be applied to the shape known for shape memory materials the unfolded, the diameter of the hollow organ to be treated corresponding shape. If the stent thus produced is then compressed into the small-diameter state and introduced into a stenosed blood vessel, for example by means of a catheter, then the stent can be returned to the previously impressed shape by heating to above the so-called conversion temperature. Optionally, this deployment process can be assisted or even completely replaced by using a balloon catheter.

The However, spring, connecting and / or receiving elements can also be made of materials exist that selected are from the group consisting of stainless steel, plastic, or self-dissolving materials. Since these materials have no shape memory properties, have to the stents made therefrom in place with the help of a Balloon catheter be deployed. In particular, the self-dissolving materials are advantageous if a stent should not be permanently placed.

Especially it is preferably provided that the surface of the stent according to the invention machined, in particular finished, smoothed, and / or polished. In this way, results in a smooth surface, in particular to the claims the biocompatibility of the stent is sufficient.

Farther is a method for producing a stent according to the invention in which the conical, radiopaque marker elements of the side facing away from the longitudinal axis of the stent of the receiving elements are inserted and passed through on this page Set welds be attached to the receiving elements.

In a preferred embodiment This method is provided that initially from a hollow cylinder consisting of a material selected from the group consisting of Stainless steel, plastic, a self-dissolving material or a Shape memory material a tubular stent blank is cut out. Particular preference is further provided that the spring, connecting and / or receiving elements of the wall segments using laser or water jet cutting from the stent blank getting produced.

in the Below is an embodiment of the Invention explained in more detail with reference to drawings. Show it:

1 a schematic representation of a stent according to the invention 10 in developed form,

2 an enlarged partial view of the end of the in 1 shown stents, and

3 a plan view of a section along the line AA in 2 ,

1 shows a schematic plan view of a not yet expanded stent according to the invention 10 , The stent 10 is cut by laser radiation from a tube of a suitable material, for example a shape memory material. The stent 10 has a longitudinal axis 11 as well as a grid wall 12 on that from the individual wall segments 13 is constructed. The wall segments 13 exist in the unexpanded state of mutually parallel spring elements 16 that have fasteners 14 with spring elements 16 from the adjacent wall segment 13 are connected.

Furthermore, the stent 10 at the tube end 15 arranged receiving elements 17 on, which are formed in a loop-shaped and recesses 18 have in which marker elements 19 are arranged from a radiopaque material, such as tantalum. The recesses 18 and the marker elements 19 have an oval cross-section. The stent also has terminal, preferably finger-like spring elements 20 on, these and the receiving elements 17 are designed and arranged so that in the direction of the tube ends 15 pointing ends of the elements 20 . 19 are arranged flush and a circular, transverse to the longitudinal axis 11 of the stent 10 Describe arranged perimeter.

Advantage of this embodiment is that the tube ends 15 of the stent 10 in the deployed state exert a better support on the vessel wall, with the result that the length of action of the stent, ie the area in which, for example, a re stenosis can be effectively prevented, is significantly greater. In addition, this embodiment has the advantage that when placing the stent 10 ie pushing forward with the help of a catheter, the pressure is more uniform over the entire circumferential surface of the stent 10 is distributed and so prevents individual terminal elements 17 . 20 cut into the vessel wall.

1 also leaves the approximately S-shaped shape of the connecting elements 14 detect. It is also clear in the figure that adjacent wall segments 13 are each offset from each other, preferably by the width of two spring elements 16 ,

The connecting elements 14 and spring elements 16 thus form a continuous longitudinal web having a component in the axial direction of the stent for receiving compressive or tensile stresses in the longitudinal direction. Due to the described offset, the longitudinal web has a grid wall 12 of the stent 10 helical circumferential shape.

After cutting the in 1 The pattern thus produced into a tubular blank made of shape-memory material becomes the stent thus produced 10 expanded into a second state having a larger diameter than the first state. This second condition becomes the stent 10 then imprinted in a known manner. For implantation by means of a catheter, the thus prepared stent 10 then compressed into a state of small diameter. After the desired positioning, the stent 10 then expanded by heating over the so-called conversion temperature back into the impressed form of the second state.

2 shows an enlarged partial view of the end of the in 1 shown stents 10 with the fasteners 14 , the spring elements 16 , the recesses 18 the receiving elements 17 and the marker elements disposed therein 19 and the terminal spring elements 20 , The marker elements 19 are by means of welding points 21 , on the longitudinal axis opposite side of the stent in the receiving elements 17 attached.

3 shows a plan view of a section through a stent according to the invention 10 along the line AA in 2 , Shown is a receiving element 17 , a recess 18 , one in the recess 18 arranged marker element 19 , two terminal spring elements 20 as well as two welding points 21 ,

The receiving element 17 is transverse to its longitudinal direction circular arc around the longitudinal axis 11 of the stent 10 curved. The recess 18 points in the direction of the longitudinal axis 11 tapered cross-sectional areas. The radiopaque marker element 19 is conical and radial to the longitudinal axis 11 in the recess 18 of the receiving element 17 arranged. The marker element 19 is therefore similar to the keystone of a Roman vault in the receiving element 17 arranged.

This ensures that the marker element 19 not in the direction of rejuvenation of the cross-sectional areas of the recess 18 can move even if it breaks or corrodes. At most, it may be contrary to the direction of tapering of the cross-sectional areas of the recess 18 replace, ie towards the wall of the hollow organ, where it does no harm.

It should be emphasized once again that the recess 18 and the marker elements 19 may have round or substantially rectangular cross-sections, and that the marker elements may be formed radially conical in the form of truncated cones or conical in the form of truncated pyramids.

Under the term "round Cross sections "should doing circular, oval and elliptoid cross sections are understood. Under the term "essentially rectangular cross sections "should while also such cross-sections fall on rectangles with rounded ones Corners are traceable.

10

stent

11

longitudinal axis

12

grid wall

13

wall segment

14

connecting element

15

tube end

16

spring element

17

receiving element

18

recess

19

marker element

20

terminal spring element

21

WeldingSpot

Claims (21)

Stent ( 10 ) for implantation in or around a hollow organ, with one about a longitudinal axis ( 11 ) extending tubular grid wall ( 12 ) of elastic wall segments ( 13 ), which are circumferentially along the longitudinal axis ( 11 ) arranged one behind the other and via connecting elements ( 14 ) are connected to each other with tube ends located at opposite axis ends ( 15 ), wherein the wall segments ( 13 ) Spring elements ( 16 ) having an elastic structure, and at least one receiving element ( 17 ), with the spring elements ( 15 ), and wherein the receiving element ( 17 ) at least one recess having a cross-section ( 18 ), in which a marker element ( 19 ) is arranged from a radiopaque material, characterized in that the recess ( 18 ) one in the direction to the longitudinal axis ( 11 ) has a conically tapering cross-section, and the radiopaque marker element ( 19 ) conically and radially to the longitudinal axis ( 11 ) in the recess ( 18 ) of the receiving elements ( 17 ) is arranged. Stent according to claim 1, characterized in that the recess and the marker element have round cross sections, and the marker element radially conical formed in the form of truncated cones is. Stent according to claim 1, characterized in that the recess and the marker element have substantially rectangular cross-sections, and the marker elements conical in the form of truncated pyramids are formed. Stent according to one the claims 1-3, by characterized in that the marker elements on their longitudinal Axis facing away from the side with the receiving elements are welded. Stent according to one the previous claims, characterized characterized in that the receiving elements at the tube ends of the stent are arranged. Stent according to claim 5, characterized in that the receiving elements at the tube ends of the stent are arranged circumferentially. Stent according to claim 6, characterized in that at the tube ends in addition to the receiving elements terminal spring elements ( 20 ) are arranged circumferentially. Stent according to claim 7, characterized in that at the tube ends the receiving elements and the terminal ones Spring elements are arranged circumferentially alternately circumferentially. Stent according to claim 8, characterized in that the terminal spring elements and the Receiving elements are designed and / or arranged so that the pointing in the direction of the tube ends Ends of the terminal Spring elements and the receiving elements a circular, transverse to describe the longitudinal axis arranged circumferential line. Stent according to one the previous claims, characterized in that connecting elements and spring elements at least one continuous longitudinal ridge form, in the longitudinal direction of the stent, and the at least one component in the axial direction for recessing a compressive or tensile stress in the longitudinal direction having. Stent according to claim 10, characterized in that the longitudinal web a helical wall of the grid wall has circumferential shape. Stent according to one the previous claims, characterized in that the connecting elements in comparison flat to the spring elements widened are formed. Stent according to claim 12, characterized in that the connecting elements double Have width of the spring elements. Stent according to one the previous claims, characterized in that the radiopaque marker elements consist of a material selected from the group consisting gold, platinum, silver, tantalum, barium sulphate doped plastic, with bismuth trioxide doped plastic. Stent according to one the previous claims, characterized in that the spring, connecting and / or receiving elements from a shape memory material consist. Stent according to claim 15, characterized in that the shape memory material is selected from the group consisting of nickel-titanium alloys and copper-zinc-aluminum alloys. Stent according to one the claims 1-14, characterized in that the spring, connecting and / or receiving elements consist of a material selected from the group consisting made of stainless steel, plastic, or a self-dissolving material. Stent according to one of the preceding claims, characterized in that its surface is processed, in particular refined, smoothed, and / or is polished. Method for producing a stent according to the previous claims, characterized in that the conical, radiopaque marker elements from the side of the stent facing away from the longitudinal axis used in the recording elements and on this page by Set welds be attached to the receiving elements. Process for producing a stent according to claim 19, characterized in that the spring, connecting and / or Receiving elements of the wall segments by cutting from the stent blank getting produced. Method of manufacturing a stent according to claim 19 or 20, characterized in that that a tubular stent blank is cut out of a hollow cylinder consisting of a material selected from the group consisting of stainless steel, plastic, a self-dissolving material, or a shape memory material.