DE19531659A1 - Spiral stent for treating pathological body vessels, e.g. aorta - Google Patents

Abstract

The spiral stent (1) comprises a longitudinal wire (3) and is implantable by a catheter (2). The stent takes its spiral form once it is in the implantation position. The stent wire has radial fibres and/or a protruding tissue structure (2) at least partially over its outer circumference. The stent wire is a thermo-memory wire, especially made of Nitinol. The catheter has an inlet valve outside of the body for a cooled physiological saline solution. The catheter also has a stop valve inside the body for preventing the body fluids from entering the catheter. The wire is made of highly elastic material, especially of plastics. The tissue structure is at least partially a textile.

Description

The invention relates to a spiral stent for treatment pathological body vessels, at least in the form an elongated stent wire using a kathe ters is implantable and only on the implant takes its intended spiral shape.

For the treatment of pathological body and blood vessels it is known to use spiral stents made of metal or plastic to introduce a diseased body vessel. Such Be actions occur with pathological occlusions or Aneurysms, especially the aorta, are considered.

The implantation of such vascular prostheses is the result of considerable diameter of these prostheses. Mostly, only a surgical implantation of the vessel prostheses in connection with an opening of the vessel and a subsequent vascular occlusion by means of a Vascular suture possible. In the case of treatment of an aortic Aneurysms are inserted into the pelvic arteries leads. This treatment is often linked through with aortic aneurysms stenoses of the Pelvic arteries difficult or completely thwarted.  

In the cases mentioned, but also in the case of treatment smaller vessels, such as intracranial vessels it is advantageous to use stents made by a small NEN diameter for implantation to a larger diameter knives can be expanded at the implantation site. Accordingly, balloon expandable or self-expanding Stents with a suitable catheter implanted vessels.

In this context, the article "Translumi nally-placed "coil spring endarterial tube grafts, invest Radiol 1969, 4, pages 329 to 332 by Charles Dotter the use of a thermal memory wire already been written. Thermo-memory wires are mostly Niti nol wires, i.e. nickel-titanium alloys, which are used at tem temperatures around 500 degrees Celsius in a predeterminable range Cure the mold and then at room temperature or depending on the alloy at temperatures around 30 ° in this form remain. Under the "Thermo-Memory property" ver one stands that these wires with a corresponding white cooling, for example by ice water, their lose previous form and then as langge stretched wire are free to move and flexible. As soon as the wire back to about the average corresponding room temperature warmed such a wire jumps into the predefined spatial shape during curing.

Charles Dotter suggests a spiral stent from chilled thermo memory wire in the form of an elongated To implant wire, which is then due to its described thermal memory property on the implantation jumps into the desired spiral and prosthetic shape.  

Such a procedure in animal experiments is described in the subject "Percutaneous Arterial Grafting" by Andrew H. Cragg et. al. from Radiology 1984; 150, pages 45 to 49 described. After this essay, spiral stents using a cooled coaxial catheter as elongated wires to treat aneurysms implanted.

However, these experiments have shown that the Treatment methods with the risk of intimal hyperpla they, that is, a pathological growth of the vessel wall treating vessels are connected. With this treatment There is therefore the possibility of a broad method ren vasoconstriction up to the vascular occlusion as well excessive thrombo-treatment of the patients to be treated Vessels.

In addition, it is known to be therapeutic Embolization, a vascular treatment with the aim of a Vascular occlusion, the continued supply of a tumor prevent it by implaning stainless steel spirals be treated ("Steel Coil Embolus and Its Therapeutic Applications ", Sydney Wallace et al., Abrams Angiograhy, Vascular and interventional Radiology, Third Edition, Vol. III, Brown and Company, Boston 1983). In this case however, are completely coiled spirals with a Guide wire in a catheter at a suitable location in placed in the affected vessel. The spirals are additional Lich covered with wool hair or dacron fibers that are at least in sections radially from the spiral forter stretch so that due to the winding of the spiral in the space enclosed by the spiral  wise overlapping network of wool hair or fibers forms. This network becomes the desired one Vascular occlusion due to the attachment of tissue cells thrombo-organized and organized. One speaks in this Connection of embolization spirals. The difference to the previously mentioned treatment method embolization spirals already in spiral implanted form and form within the body vessel a ball that due to its thrombogenicity a Vascular occlusion causes. The stents previously described keep the lumen of a body vessel open.

The invention has for its object a spiral stent with improved physical tolerance, in particular with regard to the risk of intimal hyperplasia to accomplish. The spiral stent according to the invention is said to be there beyond tissue formation, especially in connective tissue treatment with aneurysms along the Accelerate stent wall.

This object is achieved in that the spiral stent according to the preamble of claim 1 Stent wire of the spiral stent at least partially one beyond the outer circumference of the stent wire tissue structure and / or with itself radially from this wire is provided with extending fibers.

This spiral stent continues to offer the advantage of facilitated implantation as an elongated wire through an appropriate catheter. The more voluminous Spiral form only occurs at the implantation site where the Stent wire due to its thermo-memory property or due to its elasticity in its intended  appropriate form jumps. The latter can in particular Use a plastic wire.

The spiral then has its intended position stent in the form of a wire loop skeleton, the individual loops through the ones connected to the wire Tissue structures or fibers opposite the vessel wall are shielded and by overlapping each other Tissue structures or fibers are interconnected. Thus, the entire spiral stent body is not made of wire formed, but also consists partly of fiber or Tissue sections. This makes the total length stent wire to be implanted compared to pure wire shortened stents. In any case, however, is the wire loop skeleton of the spiral stent completely opposite shielded the vessel wall. As a result, the body ver The sluggishness of the spiral stent improved.

A decisive advantage of the spiral according to the invention However, stents is that unlike the previously known wire stents with abutting Wire loops are now in the area of the fabric and fiber cut the walls of the new spiral stent membrane properties, for example a diffusibility, exhibit. The walls of the vessel can thus initially in the Paths of diffusion continue to be supplied. In addition is a possible drug administration by the new stent wall not affected. This is the danger any intimal hyperplasia of the patient to be treated Vascular walls drastically reduced.

Another advantage is seen in the fact that a increased attachment of connective tissue cells or a  increased thrombo-area in the area of tissue or Fiber sections of the stent wall results. The difference the inventor forms part of the well-known embolization spiral spiral stent according to the invention is a tube provided with fibers, that the vessel lumen leaves open. Because of the described Cell attachment is gradually due to the thrombogenesis biological structure Wall formed. In this way, for example, aneurysms men from the normal blood flow, with what the risk of rupture of the aneurysm continues to act sam is prevented.

A particularly gentle and simple implantation of the Spiral stenting is particularly possible if the stent wire used is a thermal memory wire. On due to its well-known thermal memory property is in in this context the use of nitinol wires very cheap. However, there are also plastic filaments with suitable thermo-memory properties.

The stent wire made from a thermo-memory wire should be through one with physiological saline cooled catheters to be implanted to avoid that the stent wire is already inside the catheter voluminous spiral shape jumps and thereby the the Im friction between the stent wire and the inner wall of the catheter is enlarged.

Instead of the spiral made of thermo-memory wire wires can also be highly to super-elastic Wires are used as stent wire, which as a result their elastic properties at the implantation site in get their intended spiral shape. A derar  Tiger stent wire can be made of appropriate plastics but also be made of nitinol.

According to claims 5 and 6, the fabric structures to create the diffusible membrane sections just as much from a textile as from a metal structure be made. In case of using textile fabrics weave the membrane sections have smaller pores and Larger pores if metal mesh is used on. For a solution with small-pored tissue sections there is thrombosis and organization of the brought structures accelerated. Metal mesh structures may have the advantage of a higher cross stability on.

The transverse stability of such a spiral stent can can also be increased in that the tissue structures cut into fringes at least in sections are. The fabric structures can match at stiffening and sealing overlap the length of the fringes pend interlock.

In the event that the stent wire at least in sections is provided with radially extending fibers, it is advantageous to determine the length of the fibers of each Select application accordingly. For example wise in connection with the treatment of aneurysms conceivable to measure the length of the fibers so that the Braid these fibers preferably in the appropriate Vessel sack protrudes into the area increased vascular thrombosis takes place. This would accelerate through ongoing thrombosis of the pathological vascular sac  accelerates. It is also conceivable that the fibers be preferably protrude into the interior of the spiral stent by one Form anastomosis with an underlying stent. That means the connection to a second inserted The stent is better sealed during this training.

The spiral stent can be used without using the body Adhesives that also have dubious durability are manufactured in such a way that at least one Stent wire including tissue structures or Fibers are wrapped and / or wrapped. This wrapping or wrapping by means of another textile or Thread. An additional attachment of the Ge weave structures or fibers are not required.

In a further embodiment, the attachment of the Ge weave structures or protruding fibers simply because of it done that as a stent wire one of several wires th entangled stent wire is used, whereby within the entanglements of the stent wire, the Ge weave structures or fibers are kept. This one too Execution is the use of additional glue or other fasteners can be dispensed with.

According to claim 11, the spiral stent can be particularly advantageous is responsible for the "kissing stent method" Treatment of the abdominal aorta can be used. At This method is already used in the distal lumen implanted main stents on the distal side via one ar teria-femoralis two secondary stents in the distal lumen of the main stent and then expanded. With this treatment method, the problem arises that the secondary stents inserted on the distal side are not that  Lumen of the main stent already implanted completely fill out so that in the area of this branch of the Spiral stents result in undesirable leakage. In ver It is therefore binding with this "kissing stent method" advantageous to have a spiral stent at its distal end is provided with fibers, which are preferred in the stent protrude. This results in an accelerated Ge Barrel closure in the area of the anastomosis if a derar tiger spiral stent is used as the main stent.

According to the statements according to claims 12 and 13 the risk of leakage in the area of the distal ver branch of the main stent is also noticeably reduced.

The fact that the stent wire ver with stiffening struts see that is parallel and during implantation standing across the stent wire after implantation an additional transverse stiffening of the spiral stent ben. A special stiffening effect is always then achieved when the length of each wire section like this it is dimensioned that at least two adjacent loops of the spiral stent by one stiffening strut each be gripped. A possible realization of a derar cross bracing of the stent spiral is thereby prevented ben that the stiffening struts have a larger through have knife than the stent wire and thus according to Ver leave the catheter in its intended position reach if the spiral stent is otherwise already here represents is. The intended expansion of the spiral stents due to elasticity or thermal memory The property of the stent wire is therefore determined by the ver stiffening struts not hindered.  

Another shortening of the stent to be implanted wire results from a double-barreled spiral structure is implanted.

In another version, the thermal memory Property of the thermo-memory wire or the elasti of a plastic wire is also used in this way individual loops of a spiral stent, which are attached to a guide wire after success implantation within the vessel to be treated open into the desired spiral shape.

According to claim 17, this embodiment can me can be supported mechanically during the implan tation of the spiral stent using the loops a detachable apron in your on the guidewire folded position are kept.

In an embodiment according to claim 18 there is a improved spring action in the longitudinal direction of the spiral stents. As a result, the body tolerance of the Spiral stents, especially when implanted in The curve or flexion area of vessels can be increased. Due to the waveform of the stent wires, one too additional interlocking of the spiral loops can be achieved and thereby the transverse rigidity of the Spiral stents are increased.

The implantation of such a spiral stent and its Correct placement can be facilitated that the stent wire is provided with special markings is the observation of the spiral stent on the X-ray lighten gene screen.

A durable attachment of the fabric structures or company  is possible if the stent wire has a longitudinal oval or rectangular cross-section, since this is a extensive contact of the fabric or the fibers with the Results in stent wire.

Below, the invention is based on several in the attached drawing schematically illustrated Ausfüh Examples explained. Not to scale show:

Fig. 1 is a spiral stent,

Fig. 2 a connected wire with a fabric structure stent,

Fig. 3 shows a cross-section of the stent wire along the line III-III in Fig. 2,

Fig. 4 shows the stent wire of FIG. 3 within a Ka theters,

5 shows a connected with a frangible web structure stent wire.,

Fig. 6 shows a stent wire portion of tangled wires enclosed-fiber structure,

Fig. 7 shows a stent wire coated with encapsulated fiber structure,

Fig. 8, in a sectional view, a stent in longitudinal section Kissing-

Fig. 9 shows the Kissing stent of Fig. 6 with Innenfaserung at the distal end in cross-section,

Fig. 10 is a longitudinal oval kissing stent in cross-section,

Fig. 11 is a kissing stent constriction in cross-section,

Fig. 12 shows a stent wire having transverse ribs,

Fig. 13 is a spiral stent with a corresponding Querverrippung,

Fig. 14 is a spiral stent with an undulating wire stent,

Fig. 15 fen a spiral stent with foldable Drahtschlau and

Fig. 16 is a double-barreled spiral stent.

Fig. 1 shows a spiral stent 1 immediately after its implantation, which is still connected to a catheter 2. A stent wire 3 is advanced through the catheter 2 during implantation by means of a pusher, not shown. This stent wire 3 optionally consists of a thermo-memory wire, such as Nitinol, or an elongated, flexible wire made of highly elastic plastic, which is pushed through the catheter 2 and exits from the catheter 2 at the proximal end within the vessel to be treated and because of the mentioned thermal memory property or the elasticity of the wire jumps into the desired spiral shape of the spiral stent 1 .

In the case of using a thermal memory wire, the catheter 2 should be flushed with a cooled physiological saline solution to prevent the stent wire 3 from jumping inside the catheter 2 into the spiral shape. Otherwise, the advancement of the stent wire 3 within the catheter 2 disabling frictional force would by the bulky stent wire 3 considerably increased. To this end, the catheter 2 may be provided an inlet valve for the phy siologische solution at distalsei-side end and also on the proximal malseitigen end of the catheter 2, a lock valve to be sorted, which although allowing the physiological Kochsalzlö leak solution without hindrance, but conversely the A occurs by warm body fluids prevented.

The stent wire 3 is connected to a fabric or metal structure 4 . The structure 4 can be glued to the stent wire 3 , for example. The spiral stent can be produced by the stent wire 3 being glued in its spiral shape with a structure 4 that the closed spiral shown in Fig. 1 is formed. On closing the closed spiral structure along the formed of the stent wire 3 wire loops 5 are cut so that the unwound stent wire 3 is each connected to a both sides protruding bonded fabric structure 4 shown in Fig. 2 Darge provides. In this elongated form, the stent wire 3 can be implanted through the catheter 2 .

In the case of the implanted spiral stent 1, it is therefore possible to distinguish between the wire loops 5 and the membrane sections 6 formed by the tissue or metal structure 4 . The membrane sections 6 are diffusible due to their porosity. In the case of textile fabric structures, the membrane sections 6 are very fine-pored and in the case of using Metallge weave very large-pored. The decision to use a textile or metal structure depends on the desired stiffness of the spiral stent and the required diffusion properties.

The rectangular cross-section shown in Fig. 3 of the stent wire 3 makes it clear that due to this cross-sectional shape of the stent wire, a flat contact of the tissue structure 4 to the stent wire 3 is given. This is particularly advantageous when using an adhesive connection between the stent wire 3 and the tissue structure 4 .

According to FIG. 4, the flexible fabric structure 4 is a space-saving folded around the stent wire 3 during the implantation by the catheter 2. This facilitates the implantation of the spiral stent 1 .

The fabric or metal structure 4 can additionally be cut like a fringe according to FIG. 5. In an advantageous embodiment of this embodiment, the tissue fringes 7 of adjacent wire loops 5 overlap in the manner of a piano tape such that an additional transverse stiffening for the spiral stent 1 is given. The activity of the membrane sections 6 depends in this embodiment substantially on the width of the incisions in the tissue or metal structure 4 .

In another embodiment of the spiral stent 1 , the stent wire 3 is provided with fibers 10 which extend radially away from the stent wire 3 . The fibers are mostly made of Dacron material and can be from section by section or depending on the preferred direction of different lengths.

Fig. 6 shows an embodiment in which the stent wire 3 is made of intertwined wires 11 and 12 . The partial wires 11 and 12 also consist of thermo-memory wire or highly elastic plastics. Dacron fibers 10 are held between the individual wires 11 and 12 by means of the interlacing of these wires 11 and 12 . This version does not require any foreign adhesives with doubtful or limited durability.

In another embodiment of the spiral stent 1 , a stent wire 3 is wrapped in a sheath 13 . In order to cover 13 may also consist of a textile or metal structure 4 . However, it can also be an auxiliary thread or auxiliary wire. In this embodiment, the sheath 13 is wrapped around the stent wire 3 in such a way that in addition ra dial of the stent wire extends Dacron fibers 10 are included.

The fibers 10 extending from a stent wire 3 in accordance with the exemplary embodiments according to FIGS . 6 and 7 also serve to form membrane sections 6 between the individual wire loops 5 of the spiral stent 1 . The braid formed by the overlap of the individual fibers 10 can, however, also be used very specifically to produce thromboses, for example within a pathological vascular sac, such as an aneurysm.

According to another embodiment, the fibers 10 can also project into the interior of the spiral stent 1 in order to accelerate any vascular occlusion.

Figs. 8 to 11 show a stent for a particular method of treatment for vascular diseases in the range of arterial branches. The pelvic arteries that branch off from the aorta-abdominalis are often affected, particularly in the case of the aorta-abdominalis due to infrarenal aneurysms. A stent used to treat these vascular diseases must also have a corresponding branch. The so-called "kissing stent method" is successfully used for this purpose. In this case, a larger main stent 14 is implanted in the branching vessel and then a further auxiliary stent 17 , 17 'is inserted distally into the initially implanted stent through the branching vessels. In the case of a pathological abdominal aorta, an auxiliary stent 17 , 17 'is inserted through the aorta-femoralis into the distal lumen of the main stent 14 already implanted. So far, it was problematic that there was a leak in the region of the branching of the two distal-side inserted auxiliary stents 14 , since the auxiliary stents 17 , 17 'inserted laterally on the distal side did not fill the entire lumen of the originally implanted main stent 14 . In the case of the section-wise arrangement of inwardly projecting fibers according to FIG. 9 at the distal end of the main stent 14 , the described leakage can be effectively combatted since there is an accelerated thrombo-isolation within the leakage zones.

According to FIG. 10, the leakage can also be restricted in that the main spiral stent 14 has a longitudinally oval lumen at the distal end or is provided with a central constriction 15 according to FIG. 9. Combinations of the spiral stent solutions shown in FIGS. 9 to 11 for carrying out the kissing stent method are of course also conceivable.

According to FIG. 12 of the stent wire 3 may additionally be Ver steifungsstreben with 15 is connected. The Versteifungsstre ben 15 could, for example, be welded onto the thermo memory wire Nitinol wire sections. Another method for fastening such stiffening struts is so-called "crimping".

Ideally, the stiffening struts 15 lie parallel to the stent wire 3 during the implantation through the catheter 2 . Only at the implantation site within the vessel to be treated do the stiffening bars 15 reach their intended position transverse to the wire loops 5 of the spiral stent 1 due to their thermal memory properties or due to their elasticity. Ideally, the length of the stiffening struts 15 is dimensioned such that the adjacent wire loops 5 are covered. This results in an additional transverse stiffening of the spiral stent 1 .

An improved spring property of the spiral stent in the longitudinal direction can be achieved in that the stent wire 3 jumps into a wave shape at the implantation site, as shown in FIG. 14. The individual wire loops 5 are then formed from wavy bent stent wires 3 . An additional cross stiffening effect results when the wave-shaped bulges from the stent wire 3 overlap each other in a manner not shown.

In a further embodiment according to FIG. 15, the individual wire loops 5 are fastened to a guide wire 16 . During the implantation, the wire loops 5 are placed as closely as possible on the guide wire 16 and then jump after implantation at the implantation site due to their thermal memory property or their elasticity into the desired spiral shape. During the implantation, the individual wire loops can additionally be held in their folded position by a detachable crochet.

If according to FIG. 16 two parallel stent wires 3, 3 may be 'bonded to a fabric structure 4 a dop pelläufiger spiral stent can be produced. As a result, the length of the stent wires 3 , 3 'to be implanted is shortened with the same stent length.

Reference list

1 spiral stent
2 catheters
3 stent wire
4 fabric or metal structure
5 wire loops
6 membrane section
7 fabric fringes
8 - - -
9 - - -
10 fibers
11 wires
12 wires
13 wrapping
14 main stent
15 stiffening struts
16 guide wire
17 , 17 ′ auxiliary stent

Claims (20)

1. Spiral stent for the treatment of pathological body vessels, which can be implanted in the form of at least one elongated stent wire ( 3 ) by means of a catheter ( 2 ) and only assumes its intended spiral shape at the implantation site after the implantation has taken place, characterized in that the stent wire ( 3) at least partially with a projecting beyond the outer periphery of the stent wire (3) tissue structure (4) and / or radially from the stent wire (3) forterstreckenden fibers (10) is provided. 2. Spiral stent according to claim 1, characterized in that the stent wire ( 3 ) is a thermal memory wire, in particular made of nitinol. 3. Spiral stent according to claim 2, characterized in that the implanted catheter ( 2 ) has an inlet valve located outside the body for a cooled physiological saline and an in-body shut-off valve which prevents the entry of body fluids into the catheter ( 2 ). prevents, has. 4. Spiral stent according to claim 1, characterized in that the stent wire ( 3 ) is a highly to super-elastic wire, in particular made of plastic. 5. Spiral stent according to one of the preceding claims, characterized in that the tissue structure ( 4 ) is at least partially a textile structure. 6. Spiral stent according to one of claims 1 to 4, characterized in that the tissue structure ( 4 ) is at least partially made of metal mesh. 7. Spiral stent according to claim 5 or 6, characterized in that the tissue structure ( 4 ) is cut into fringes at least in sections. 8. Spiral stent according to one of the preceding claims, characterized in that the fibers ( 10 ) extending radially from the stent wire in sections and / or depending on the radial preferred direction are of different lengths. 9. Spiral stent according to one of claims 1 to 8, characterized in that at least one stent wire ( 3 ) is encased and / or wrapped, including protruding tissue structures ( 4 ) and / or radially projecting fibers ( 10 ). 10. Spiral stent according to claim 9, characterized in that a plurality of part wires ( 11 , 12 ) including projecting tissue structures ( 4 ) or protruding with each other to a stent wire ( 3 ) are entwined. 11. Spiral stent according to claim 8, characterized in that a main spiral stent ( 14 ) at least at one end has fibers ( 10 ) which preferably protrude into the interior of the stent. 12. Spiral stent according to one of the preceding claims, characterized in that the main spiral stent ( 14 ) has at least at its distal end an oval lumen. 13. Spiral stent according to one of claims 1 to 11, characterized in that the main spiral stent ( 14 ) we at least at its distal end is constricted in such a way that its lumen at this point has at least approximately the shape of an eight. 14. Spiral stent according to one of the preceding claims, characterized in that the stent wire ( 3 ) is provided with stiffening struts ( 15 ) for transverse stiffening of the spiral stent, which are parallel to the stent wire during implantation and after implantation has taken place ( 3 ) . 15. Spiral stent according to one of the preceding claims, characterized in that two stent wires ( 3 , 3 ') are firmly connected to one another through the tissue structure ( 4 ) to form a double-barreled spiral structure of the spiral stent ( 1 ). 16. Spiral stent according to one of the preceding claims 1 to 14, characterized in that the individual loops ( 5 ) of a spiral stent ( 1 ) are formed by an individual stent rings, which during implantation on a guide wire ( 16 ) or on Guide tube which can be pushed in via a guide wire ( 16 ) and can be folded out into the respective spiral shape after the intended implantation. 17. Spiral stent according to one of the preceding claims, characterized in that the spiral stent ( 1 ) is initially stretched to carry out the implantation and is then held in this extension by means of a releasable constriction. 18. Spiral stent according to one of the preceding claims, characterized in that the stent wire ( 3 ) after the intended implantation at least in sections within the lateral surface of the spiral stent ( 1 ) is curved in such a way that the helix of the implanted spiral stent ( 1 ) at least from sections of a wavy curved stent wire ( 3 ) is formed. 19. Spiral stent according to one of the preceding claims, characterized in that the stent wire ( 3 ) is provided with markings, which facilitates observation of the spiral stent ( 1 ) on the X-ray screen. 20. Spiral stent according to one of the preceding claims, characterized in that the stent wire ( 3 ) has a longitudinal oval or rectangular cross section.