DE10127602A1 - Stent consists of hollow cylindrical main part of intersecting filaments forming mesh with cells, and at least pairs of free ends - Google Patents

Abstract

The hollow cylindrical main part (12) of the stent consists of filament-like elements (22,24) staggered in position around the periphery. The filaments form a mesh (18) interwoven with polygonal cells(20). On at least one end (14,16) of the main part, the filaments intersect at least in pairs (28,30) at peripherally distributed intersection-end points from which the free ends (32,34,38,40) lead away in pairs at least. At least three of the free ends are fixed together.

Description

The invention relates to a stent for implantation in humans body, especially in blood vessels, with a hollow cylin drical body made up of a plurality of circumferentially against staggered thread-like elements is built up, the to a network with a multitude of polygonal cells are intertwined, with the thread-like elements at least one end of the body at a widely distributed intersection point at least in pairs, and where of the Free ends of the filiform ele leading away from crossing points elements are fixed to each other at least in pairs.  

Such a stent is known from DE 197 50 971 A1.

An endoprosthesis is generally opened under a stent keeping gait-like structures in the human body, e.g. of blood vessels such as veins or arteries. By Im Plantation of a stent is said to narrow the corresponding one Vessel, the z. B. due to external pressure be knitted.

They are self-expanding stents as well as by means of egg Nes balloon catheter known, for example. Expandable stents.

A self-expandable stent can be placed on an applicator stretch in its longitudinal direction, causing the diameter to widen of the stent can be reduced for implantation. Using the appli kators, the stent is stretched or tensioned in implanted the vessel. After the stent is through the applicator is positioned at the desired location in the vessel the applicator removed. Now that there is no external longitudinal expansion forces act on the stent, the stent relaxes due to its cellular structure elastic in its original length, radially expands and nestles thereby adhere to the inner wall of the vessel. This can also be done be reinforced that materials with a shape memory ver be applied.

The stents for implantation in blood vessels have a hohlzy lindrische body, whose outer diameter roughly the In diameter of the respective blood vessel into which the stent is placed to be planted corresponds. The body of the stent is thus open in the longitudinal direction for the passage of blood. The  The body of the stent is made up of several mutually offset fa the shaped elements built into a mesh with egg A large number of polygonal cells are intertwined. The Ge Braid can, for example, be constructed in the same way as in the case of the the aforementioned DE 197 50 971 A1 known stent is the case that two intersecting groups of thread-like elements so are crossed with each other that each filiform element of the a crowd alternately above and below each filiform ele ment of the other group. Such a bond of Ge wicker is called a canvas weave.

The stent known from DE 197 50 971 A1 has one End of the body on a closed braid by connecting to the end of each thread-like element from the opposite Arrived at the end and redirected to that end again is returned to the braid.

At the "open" end opposite the end, the the closed braid has free ends of the thread-like elements that pair in the known stent are twisted together. There are two free ones Ends leading away from the same respective crossing end point ren, twisted together in the longitudinal direction of the stent.

In the case of a stent, the body of which consists of a total of 16 threads elements are built from one end des stents from 8 pairs of twisted free ends. However, these free twisted ends have several disadvantages. When inserting the stent into a blood vessel with the twisted Free ends ahead can bend these free ends outwards conditions and get caught with or get into the inner wall of the vessel  sting, which can injure the vessel wall, and except this is then no longer the advancement of the stent possible and the stent must be pulled out of the blood vessel again be. There is also a risk that these few wise free ends twisted together, thus total are very thin, due to the appropriate contact pressure on the Ge can penetrate the inner wall of the barrel or wax into it nen, which is also undesirable.

Yet another disadvantage of pairing these together bare free ends is that in the event that the Stent is a self-expanding stent, the radial expansion on force of this end and thus the contact pressure on the vessel nenwand is not optimal. The radial self-expansion capacity and the associated secure hold of the implanted However, stents are important requirements for such Stent.

The invention is therefore based on the object of a stent type mentioned in such a way that the before mentioned disadvantages are avoided, in particular that the risk that the free ends when inserting the stent drill into the wall of the vessel so that the free ends over time penetrate the vessel wall or ver grows reduced and the radial self-expansion capacity at End of the stent is increased.

According to the invention, this object is achieved with regard to the input mentioned stents solved in that at least three of each free ends by three different crosses  end points come, brought together and fixed to each other are.

The stent according to the invention thus frees itself from the concept, depending because there are two free ends of the thread-like elements by the come to the same intersection end point to fix each other. It will now have at least three free ends, namely those by different intersection endpoints come together and fixed to each other. Tension the at least three free ends approximately the shape of a triangle with its free one Tip the at least three free ends are fixed together. The at least three mutually fixed ends accordingly form one thicker compared to only two fixed ends and thus blunt end, which is overall more stable and thereby egg ne shows less tendency to bend, and furthermore is also the risk of cutting or penetrating into the Ge barrel wall reduced. With the same number of thread-like elements the number of protruding ends is also advantageously reduced. The at least three free ends, each of which is below come at different intersection endpoints and therefore approximately one Spread the triangle, form at the corresponding circumferential points the body of the stent has a flat contact with the vessel wall and thus contribute to an improved hold of the stent in the vessel at. Because at least three of different cross free ends coming from the end points are brought together, at least the two outer free ends run with the Longitudinal direction of the stent is not equal to 0 °, d. H. these two outer free ends have a directional compo nente in the circumferential direction of the stent, whereby the radial Expansion of the stent is also improved.  

Preferably at least three free ends are circumferential lead directly adjacent intersection endpoints, summarized and fixed together.

In a preferred embodiment there are at least four free ends by four different crosses end points come, brought together and fixed to each other.

This configuration is particularly advantageous for stents that are made up of a total of 8 or 16 thread-like elements and correspondingly have 4 or 8 crossing end points. The in Relation to the at least three merged free ones Ends are released in the case of at least four merged The ends are reinforced accordingly.

In a further preferred embodiment, they are each at least three free ends by interweaving in the form of egg nes braid fixed together.

This measure has the advantage that each of the at least 3 is free Ver ends with each other of the at least 3 free ends is braided, resulting in a very secure fixation of the gives at least 3 free ends to each other, which is essentially safe is more than just twisting two free ends together the.

In a further preferred embodiment, the threads are elements in pairs at the intersection endpoints intertwined, so that one to the respective cross end of the thread-like element and a part of the leading away from the same crossing end point  same thread-like element an angle not equal to 180 ° conclude.

By wrapping the thread-like elements in pairs the end points of the intersection ensure that the braid attaches itself cannot move or solve the intersection endpoints where due to the overall high dimensional stability of the invention Stents is reached. Furthermore, this measure the radial self-expansion capacity of the invention Stents further improved because the individual filiform Ele alternate ge at the intersection endpoints experienced sensible pull in the circumferential direction of the stent.

In a further preferred embodiment, they are at least three free ends bonded together.

The integral connection of the at least three free ends, For example, by welding or gluing is particularly as additional security measure of fixing the free ends advantageous, especially if the free ends according to the previously described configuration intertwined to form a braid are. With this measure, the fixation rises the free ends and thus the entire mesh of the stent safely avoided.

In a further preferred embodiment, the fa shaped elements at both ends of the body at circumference distributed intersection end points at least in pairs, and are at least 3 each on both ends of the body free ends that differ from the extensively different three  Intersection endpoints come, merged and fi with each other xed.

In this preferred embodiment, both ends are accordingly the body of the stent designed according to the invention, so that both ends of the stent who achieved the advantages of the invention the.

In a further preferred embodiment, the body is made of 16 thread-like elements built, and are at least one nem end 4 free ends each, that of immediately adjacent coming, merged and together who fixes.

This configuration is particularly suitable for such stents ders advantageous, which is used for implantation in blood vessels and, for example, a diameter of about 6 to 10 mm exhibit.

In a further preferred embodiment, the threads are elements made of nitinol.

Nitinol is a shape memory material that is suitable for Stents are particularly suitable due to their shape memory.

Further advantages and features result from the following the description and the attached drawing.

It is understood that the above and below Features to be explained not only in the particulars  combination, but also in other combinations or can be used on their own without the scope of the present Leaving invention.

An embodiment of the invention is in the drawing is shown and will be described below with reference to this wrote. Show it:

FIG. 1 is a stent for implantation in the human body in a front view;

FIG. 2 shows a developed representation of the stent in FIG. 1 in the region of one of its ends after the stent has been cut open along a surface line and spread out flat, the scale in FIG. 2 being reduced compared to FIG. 1;

Fig. 3 is a greatly enlarged scale section of the stent in Figures 1 and 2, wherein in Fig. 3 it is shown how 4 free ends that come from circumferentially immediately adjacent bar end points are intertwined with each other. and

Fig. 4 is a schematic representation showing a continuous manufacture of stents according to the invention as a continuous product.

In Fig. 1 is provided with the general reference numeral 10 stent for implantation in the human body, in particular for implantation in blood vessels.

The stent 10 has a hollow cylindrical body 12 which has a first end 14 and a second end 16 .

The body 12 is composed of a plurality, in the present exemplary embodiment, of a number of 16 thread-like elements which are offset circumferentially from one another and are interwoven to form a mesh 18 with a plurality of polygonal cells 20 .

The braid 18 is formed such that a first set of 8 thread-like elements 22 are wound in a first helical shape, while a second set of thread-like elements 24 are wound in a line shape opposite to the first set. Accordingly, the thread-like elements 22 and 24 at intersection end points 26 cross each other over each other.

At the crossing end points 26 , the thread-like elements 22 and 24 run alternately one above the other and one below the other. The thread-like elements 22 of the first family and the elements 24 of the second family of fadenformi thus form between the most end 14 and the second end 16 of the body 12 of the stent 10 two crossed, oppositely helical thread layers.

At the ends 14 and 16 , the thread-like elements 22 and 24 form crossing end points 28 (second end 16 ) and 30 (first end 14 ).

If, as in the present case, a total of 16 thread-like elements 22 , 24 are used, eight intersection end points 30 and eight intersection end points 28 are respectively present at both the first end 14 and 16 . The intersection end points 28 and 30 are distributed approximately equidistantly around the body 12 of the stent 10 .

From each crossing end point 28 of the second end 16 each lead two free ends 32 and 34 away. From the crossing end points 28 of the second end 16 lead accordingly according to the number of 16 thread-like elements 22 , 24 16 like free ends 32 , 34 away, the ends 32 to the host of thread-like elements 24 and the ends 34 to the host of thread shaped elements 22 belong.

In each case 4 of the free ends 32 , 34 , each of which comes from circumferentially different, immediately adjacent intersection ends 28 , are brought together and fixed to one another by interlacing in the form of a braid 36 .

In Fig. 1, this is shown in more detail for the plait 36 . To the plait 36 runs a free end 34 a coming from the crossing end point 28 a, the free end 34 coming from the crossing end point 28 coming, a free end 32 a coming from the crossing end point 28 b, and a free end 32 b coming from a crossing end point 28 c coming.

According to the number of 16 thread-like elements used, the stent 10 has four such braids 36 at the second end 16 .

At the first end 14 , the body 12 of the stent 10 is formed in an identical manner to the second end 16 , ie free ends 38 , 40 leading away from the crossing end points 30 are also combined such that four free ends 38 and 40 , respectively come from circumferentially adjacent four crossing endpoints 30 , brought together and fixed to each other in the form of a braid 42 .

The braids 36 and 42 of the stent 10 are further additionally fixed by a material connection of the individual fa-shaped elements 22 , 24 entering them, for example by placing a welding spot on the braids 36 and 42, respectively.

In Fig. 2, the second end 16 of the stent 10 is shown in a developed view, that is, the stent in Fig. 1 was cut along an arbitrarily selected surface line 44 th and spread out flat. The section along the generatrix 44 is placed in the middle by a braid 36 a.

In Fig. 2 it is indicated and in Fig. 3 shown in more detail that the thread-like elements 22 , 24 are looped around each other in pairs at the crossing end points 28 , so that a part 46 of each thread-shaped element 22 leading to the respective crossing end point 28 and one of the same End of crossing point 28 leading part 50 of the same thread-like element 22 include an angle not equal to 180 ° approximately between 90 ° and 120 °. The same applies to a part 48 leading to the crossing end point 28 and a part 52 leading away from the crossing end point 28 of each individual thread-like element 24 .

In Fig. 3 one of the braids 36 is shown during his braiding, which shows from this illustration that each free end 34 , 34 a, 32 a and 32 b each is intertwined with each to the braid 36 . The four free ends 34 , 34 a, 32 a and 32 b span from the crossing end points 28 , 28 a, 28 b and 28 c coming approximately a triangle, at the top of which the plait 36 is located. From Fig. 3 shows in particular that the outer free ends 28 a and 28 c related to. The longitudinal axis are relatively greatly inclined. The triangle spanned by the free ends 34 , 34 a, 32 a and 32 b unfolds a good elastic expansion force, which advantageously improves the self-expansion capacity of the stent 10 at its ends 14 and 16 .

The thread-like elements 22 , 24 are preferably made of nitinol.

In Fig. 4 it is shown that the stent 10 can be manufactured, for example, as a terware in a series-compatible process.

In FIG. 4, four individual stents 10 a are shown schematically to 10 d. First, the stent 10 is a braid, according to the example used. Plaited to the intersection endpoints 28 in the form of a plain weave. Free ends 34 leading away from the intersection end points 28 are then brought together in groups of at least three, in the exemplary embodiment shown four free ends coming from circumferentially spaced intersection end points 28 , and fixed to one another in the form of a braid 36 , corresponding to the circumference of the stent 10 a four such braids 36 arise.

Starting from the braids 36 , the length of which can be chosen as desired, the free ends are then passed to corresponding intersection end points 30 of the subsequent stent 10 b, and from the end points 30 of the intersection, the stent 10 b is then corresponding to the type of braid used braided to the crossing end points 28 of the stent 10 b.

Starting from the intersection end points 28 , four free ends 34 coming from adjacent intersection end points 28 are again brought together and interwoven to form braids 36 , etc. Then the stent 10 c, the stent 10 d etc. are produced in a corresponding manner.

On the respective braids 36 , the stent 10 a is connected to the stent 10 b, the stent 10 b to the stent 10 c, etc. After a certain number of such stents have been completed, the individual stents 10 a, 10 b can now be used , 10 c, etc. by separating approximately at the level of the longitudinal center of the individual braids 36 , as shown by broken lines 56 . Before the individual stents are separated along the separating lines 56 , the braids 36 , that is to say the free ends 34 forming the individual braids 36, are additionally fixed to one another by a welding point or a weld seam.

Claims (8)

1. stent for implantation in the human body, in particular re in blood vessels, with a hollow cylindrical body ( 12 ) which is made up of a plurality of circumferentially offset thread-like elements ( 22 , 24 ) which form a braid ( 18 ) with a A plurality of polygonal cells ( 20 ) are interwoven, the thread-like elements ( 22 , 24 ) on at least one end ( 14 , 16 ) of the body ( 12 ) at circumferentially distributed crossing end points ( 28 , 30 ) at least in pairs ( 28 , 30 ) cross over, and wherein free ends ( 32 , 34 , 38 , 40 ) of the thread-like elements ( 22 , 24 ) leading away from the crossing end points are fixed to one another at least in pairs, characterized in that at least three of the free ends ( 32 , 34 , 38 , 40 ), which come from extensively different union crossing points ( 28 , 30 ), are brought together and fixed to each other. 2. Stent according to claim 1, characterized in that at least at least four free ends ( 32 , 34 , 38 , 40 ), which come from circumferentially different four crossing end points ( 28 , 30 ), are brought together and fixed to one another. 3. Stent according to claim 1 or 2, characterized in that the at least three free ends ( 32 , 34 , 38 , 40 ) are fixed to each other by interlacing in the form of a braid ( 36 , 42 ). 4. Stent according to one of claims 1 to 3, characterized in that the thread-like elements ( 22 , 24 ) at the crossing end points ( 28 , 30 ) are looped around each other in pairs, such that a zungsendpunkt to the respective crossing ( 28 , 30 ) leading part ( 46 ) of a thread-like element ( 22 , 24 ) and one of the same crossing end point leading part ( 50 ) of the same thread-like element ( 22 , 24 ) include an angle not equal to 180 °. 5. Stent according to one of claims 1 to 4, characterized in that the at least three free ends ( 32 , 34 , 38 , 40 ) are integrally connected. 6. Stent according to one of claims 1 to 5, characterized in that the thread-like elements ( 22 , 24 ) at at the ends ( 14 , 16 ) of the body ( 12 ) at circumferentially distributed crossing end points ( 28 , 30 ) at least in pairs run crosswise, and that at both ends ( 14 , 16 ) of the body pers ( 12 ) at least three of the free ends ( 32 , 34 , 38 , 40 ), which come from circumferentially different three crossing end points ( 28 , 30 ), brought together and fixed to each other. 7. Stent according to one of claims 1 to 6, characterized in that the body ( 12 ) from 16 filiform elements ( 22 , 24 ) is constructed, and that at least one en de ( 14 , 16 ) at least four free Ends ( 32 , 34 , 38 , 40 ), which come from immediately adjacent intersection ends ( 28 , 30 ), are brought together and fixed to each other. 8. Stent according to one of claims 1 to 7, characterized in that the thread-like elements ( 22 , 24 ) are made of Ni tinol.