JP2002272855A - Stent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stent the diameter of which can be reduced easily and naturally in the case of inserting the stent into a small-diameter catheter in the stent formed by knitting metallic wires in the state of a mesh or cylindrically. SOLUTION: This stent 10 is constituted by knitting the metallic wires in the state of a mesh or cylindrically and pulling and gathering the wires 11 crossing or folded-back at its both end parts to integrate them to form a fixed end part 14. The part 14 can be formed by making the crossing or folded-back wires 11, e.g. to be a strand, covering the periphery of this strand with a metallic coil not-transmitting an X-ray and soldering it or fixing it with brazing metal. It is possible that an end part where the wires 11 cross or the folded-back part of the wires 11 is only pulled and gathered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stent for insertion into a tubular organ of a human body such as a blood vessel, a ureter, a bile duct, and a trachea.

[0002]

2. Description of the Related Art In recent years, stents have been inserted and arranged through catheters for treatment of tubular organs of the human body such as blood vessels, ureters, bile ducts, and trachea. For example, a treatment method is known in which a stent is disposed at a stenotic part of a blood vessel to expand the stent, or a stent is disposed at a place where an aneurysm is formed to prevent rupture of the aneurysm.

[0003] As such a stent, for example, Japanese Patent Application Laid-Open No. 11-57021 discloses that a predetermined number of filaments are twisted in a sine curve shape to form a braided structure in a cylindrical cage shape. A stent is disclosed in which both ends of the braided structure are formed into a loop structure by folding or joining the filaments, and each filament has an infinite loop with no ends as a whole.

Japanese Patent Application Laid-Open No. 2000-202033 discloses that a hollow cylindrical body is formed by braiding a plurality of filaments of a Ni-excessive Ti—Ni alloy, and the hollow cylindrical body is subjected to a low-temperature side shape memory treatment. The stent stores the applied first shape and the second shape subjected to the high-temperature side shape memory processing, and is capable of being deformed between the first shape and the second shape with a change in temperature. It has been disclosed. And it is preferable that the cross section of the filament is fixed only at both ends of the hollow cylindrical body, so that even if the diameter of the hollow cylindrical body expands and contracts according to a temperature change, it is long. It is described that the change in the height direction can be reduced.

[0005]

In recent years, the diameter of a stent delivery catheter has been reduced for the purpose of reducing the load on a patient, and the stent inserted into the catheter has also been reduced to a smaller diameter. Is required.

However, in the stent disclosed in Japanese Patent Application Laid-Open No. 11-57021, both ends of the cylindrical cage-shaped braided structure are formed into a loop structure by folding or joining of the filaments. When inserting into a catheter with a reduced diameter, the above-mentioned loop at the end is forcibly bent to or near the plastic deformation area of the metal wire, which not only requires extra force but also breaks the end and lowers the holding force. There was such a problem.

In the stent disclosed in Japanese Patent Application Laid-Open No. 2000-202033, the shape of the stent must be controlled by injecting cold saline or hot saline through a catheter during insertion into the body. However, there is a problem that the insertion operation becomes complicated.

Further, in the stent disclosed in Japanese Patent Application Laid-Open No. 2000-202033, the diameter of the stent is reduced by utilizing the superelasticity of a shape memory alloy, instead of being reduced or expanded by temperature change, and passed through a catheter. It is conceivable to insert it into the body and expand the diameter by pushing it out of the catheter, but since it is fixed at a point with both ends crossed,
The strength at the intersection is a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stent formed by knitting a metal wire into a mesh and a tube so that the diameter can be reduced easily and easily when inserted into a catheter. .

[0010]

Means for Solving the Problems In order to achieve the above object, a first aspect of the present invention is to provide a stent formed by knitting a metal wire in a mesh shape and a cylindrical shape, in which a wire material that crosses or folds at both ends in an axial direction. It is intended to provide a stent characterized by being aligned.

According to the above invention, when trying to reduce the diameter of the stent at the time of insertion into the catheter, the portions where the wires intersect or fold at both ends are previously aligned in the axial direction. However, there is no need for extra force as in the case of looping back,
The diameter can be smoothly and smoothly reduced.

According to a second aspect of the present invention, in the first aspect, X-rays are added to portions of the wires at both ends which are aligned in the axial direction.
A stent having a radiopaque material fixed thereto is provided.

According to the above-mentioned invention, since the positions of both ends of the stent can be visually recognized by the X-ray fluoroscope at the time of insertion into the tubular organ in the body, the stent can be accurately arranged at the affected part.

According to a third aspect of the present invention, there is provided the stent according to the first or second aspect of the present invention, wherein the wires at both ends are aligned in the axial direction to form a stranded wire and integrated.

According to the above-mentioned invention, by using a stranded wire, it is difficult to separate wires in the case of intersecting wires, and it is easy to align them in the axial direction in the case of folded wires.

A fourth aspect of the present invention is the stent according to any one of the first to third aspects, wherein the axially aligned portions of the wires at both ends are alternately shifted in the axial direction between adjacent ones. Is provided.

According to the above invention, when the diameter is reduced, the portions which are aligned and integrated in the axial direction of the wires at both ends do not interfere with each other between adjacent ones. It is possible to reduce the diameter to a small diameter.

According to a fifth aspect of the present invention, there is provided the stent according to any one of the first to fourth aspects, wherein the wires at the both ends are aligned in the axial direction, and an X-ray opaque material is placed over the wires and fixed. Is what you do.

According to the above-mentioned invention, since the X-ray opaque material is covered on the axially aligned portions of the wires at both ends, the crossed or folded portions are securely bound.
It becomes difficult to separate and open, and can also serve as an attachment of a radiopaque material.

[0020]

1 to 5 show one embodiment of a stent according to the present invention. This stent 10
As shown in FIGS. 1 (a) and 1 (b), is formed by knitting a predetermined number of metal wires 11 into a mesh and a tubular shape.
FIG. 1A is a perspective view, and FIG.
FIG. 7 is a perspective view showing a rear side cut in half in the axial direction in parallel with the paper surface in the state of FIG.

In this case, as the material of the metal wire 11, a shape memory alloy imparting a shape memory effect by heat treatment or superelasticity is preferably employed. However, depending on the use, stainless steel, tantalum, titanium, platinum, gold or the like is used. , Tungsten, or the like may be used. As a shape memory alloy, Ni-
Ti-based, Cu-Al-Ni-based, Cu-Zn-Al-based and the like are preferably used. Further, the surface of the shape memory alloy may be coated with gold, platinum or the like by plating or the like.

The thickness of the metal wire 11 is not particularly limited, but is, for example, 0.08 to
1 mm is preferred. The outer diameter of the stent 10 is 2 to 5
0 mm is preferred.

Various weaving methods can be used for weaving the metal wire 11. In this case, the intersection of the metal wire 11
Except for both ends of the stent 10, it is preferable that it is not fixed. By not fixing the intersections of the metal wires 11, the degree of freedom of displacement between the wires 11 is increased, and it is possible to easily reduce the diameter when inserting the catheter or expand the diameter when pushing out from the catheter.

The feature of the present invention resides in that the wire material 11 that intersects or folds at both ends of the stent 10 is axially aligned and integrated to form a fixed end portion 14. FIG. 2 shows an example of a method for manufacturing the fixed end portion 14. As shown in FIG. 2A, for example, a pair of wires 11
Of the stranded wire 11 as shown in FIG.
As shown in FIG. 3 (c), the outer periphery of the stranded wire 11b is covered with an X-ray opaque metal coil 12. Furthermore,
As shown in FIG. 1D, a solder or metal braze 13 is fixed from the outer periphery of the metal coil 12 to form a fixed end portion 14.

The thus formed fixed end portion 14 is shown in FIG.
As shown in the figure, the outer periphery of the stranded wire 11b of the metal wire 11 is covered with an X-ray opaque metal coil 12, and solder or metal braze 13 is further fixed from the outer periphery of the metal coil 12, and the solder or metal The braid 13 makes the stranded wire 11
b, the metal coils 12 are fixed to each other. The ends of the pair of wires 11 are stranded wires 11b, so that the wires 11 are aligned in the axial direction A to form the fixed ends 14.

FIGS. 2 and 3 show an example in which the ends of a pair of wires 11 are bound as a stranded wire to form a fixed end portion 14. The folded portion of the wires 11 is bound as a stranded wire, and The fixed end can be formed in the same manner as described above. Further, since the binding can be performed by covering the metal coil 12, the intersection of the wires 11 does not necessarily have to be a stranded wire.

As the material of the X-ray opaque metal coil 12, for example, gold, platinum, iridium, tantalum,
Tungsten, silver, etc., and alloys containing them are preferably used. The radiopaque material is preferably attached to the fixed end portion 14 in the form of the metal coil 12, but is not limited to such a mode. For example, the radiopaque material itself may be used. Melted and stranded wire 1
For example, a method of fixing to 1b may be adopted.

Further, the X-ray opaque material may be formed in a tube shape. In this case, it is preferable to cover the ends of the pair of wires 11 and crimp from the outside.

The stent 10 thus formed is shown in FIG.
As shown in (c), it can be formed according to the shape of the affected part of the patient. As the molding method, for example, the following method can be adopted.

First, an image diagnostic apparatus such as CT, MR, etc.
An image of the tubular organ including the diseased part is obtained, only the required diseased part is extracted from the image, and an image of the optimal stent shape is created based on the image of the diseased part. Then, the file format of the stent image (for example, DICOM)
Is converted into NC processing data (for example, DXF), and a molding die is created by an NC processing machine based on the NC processing data. Next, it can be performed by setting the stent 10 in a mold and then performing a heat treatment.

The heat treatment conditions differ depending on the material of the metal. For example, in the case of a Ti—Ni-based shape memory alloy, the heat treatment condition is 35%.
It is preferably performed at 0 to 600 ° C. for 10 to 120 minutes. As a result, the stent is subjected to shape memory processing along the shape of the molding die, and is shaped into a shape similar to the shape of the molding die, as shown in FIG.

Further, as shown in FIG. 1 (d), the outer periphery and / or the inner periphery of the thus obtained stent 10 may be covered with a resin tube 20 and subjected to a grafting treatment to obtain a completed stent. In this case, as the resin tube 20, for example, polytetrafluoroethylene (PTF)
E), a woven fabric, a nonwoven fabric, a sheet, or the like made of a synthetic resin such as polyurethane (PU) or polyester are formed into a cylindrical shape, or a cylindrical shape formed by extrusion molding or the like is used.

The method of coating the resin tube 20 on the outer or inner periphery of the stent 10 includes, for example, sewing with a thread made of a material compatible with the tissue of the tubular organ, Tube 20 made of stent 10
A method of heat-welding or bonding is used. Further, it is more preferable that the end portion 21 of the resin tube 20 be folded back to the inner periphery or the outer periphery of the stent 10 so as to surround the fixed end portion 14.

As described above, the stent 10 covered with the resin tube 20 is particularly preferably employed in the case where the stent 10 is inserted into, for example, an aneurysm or the like and is itself used as a blood vessel wall. The stent used to prevent stenosis of the organ may not have the resin tube 20.

In the stent 10 thus obtained, the fixed ends 14 are formed by aligning the crossed or folded portions of the wires 11 at both ends in the axial direction and integrating them, as shown in FIG. 4A. When the diameter is reduced from the state to the state shown in FIG. 4B, the resilience at both ends of the stent 10 is small and the diameter can be reduced smoothly, so that the insertion operation into the catheter becomes easy.

FIG. 5 shows a state in which the stent 10 is placed through a catheter at the affected part of the blood vessel 20 where the aneurysm 20a is formed. This stent 10
As shown in FIG. 1 (c), is shaped in advance to fit the affected part, so that it is arranged to fit the affected part. As a result, there is no gap between the contact points A between the both ends of the stent 10 and the inner wall of the blood vessel 20, and blood flow is prevented from flowing between the stent 10 and the wall of the aneurysm 20a. Is an area into which blood does not flow due to thrombus formation. As a result, almost all blood flow passes through the
0 functions like an artificial blood vessel in that part, and can prevent rupture of the aneurysm.

Further, when an image is taken by the X-ray fluoroscopic camera 30, the fixed end portion 14 containing the X-ray opaque metal coil 12 is displayed, so that the position of the stent 10 can be accurately grasped. Misplacement of 10 can be prevented.

FIG. 6 shows another embodiment of the stent of the present invention. This stent 30 corresponds to FIGS.
Has basically the same structure as the stent of the embodiment shown in FIG. 1, and is formed by knitting a metal wire 11 in a mesh shape and a tubular shape. A fixed end portion 14 similar to that of the above-described embodiment is formed by aligning and integrating wires that cross or fold at both ends in the axial direction. However,
In this embodiment, the fixed end 14 is composed of a long fixed end 14a that protrudes in the axial direction and a short fixed end 14b that does not protrude in the axial direction.
4b are alternately arranged in the circumferential direction.

As a result, this stent 30 is
When the diameter is reduced from the state shown in (a) to the state shown in FIG. (B), the stent 30 is reduced in diameter to a smaller diameter without interference between the adjacent fixed ends 14a and 14b. Can be.

FIG. 7 shows another embodiment of the stent of the present invention. In this stent, the folded portion of the wire 11 is simply twisted into a stranded wire 11b and bound.

FIG. 8 shows still another embodiment of the stent of the present invention. In this stent, the folded portion 11c of the wire 11 is simply arranged in parallel.

FIG. 9 shows still another embodiment of the stent of the present invention. In this stent, ends 11a of a pair of wires 11 are aligned in parallel, welded and integrated.

Also in each of the stents shown in FIGS. 7 to 9, both ends of the stent can be smoothly and smoothly reduced in diameter without requiring any extra force.

[0044]

As described above, according to the present invention,
When trying to reduce the diameter of the stent at the time of insertion into the catheter, the portions where the wire intersects or folds at both ends are aligned in the axial direction in advance, so even if the catheter has a small diameter, it may be folded in a loop. Such extra force is not required, and the diameter can be smoothly and smoothly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a stent according to the present invention.

FIG. 2 is an explanatory view showing an example of a method for forming a fixed end of the stent.

FIG. 3 is an enlarged sectional view showing a fixed end of the stent.

FIG. 4 is an explanatory view showing a state in which the stent is changed from an expanded state to a reduced state.

FIG. 5 is an explanatory diagram showing a state where the stent is placed inside an aneurysm of a blood vessel.

FIG. 6 is a perspective view showing another embodiment of the stent according to the present invention.

FIG. 7 is a partially enlarged view showing still another embodiment of the stent according to the present invention.

FIG. 8 is a partially enlarged view showing still another embodiment of the stent according to the present invention.

FIG. 9 is a partially enlarged view showing still another embodiment of the stent according to the present invention.

[Explanation of symbols]

 10, 30 Stent 11 Metal wire 11a End 11b Stranded wire 11c Folded portion 12 X-ray opaque metal coil 13 Solder or metal brazing 14, 14a, 14b Fixed end

Claims (5)

[Claims] 1. A stent formed by knitting a metal wire into a mesh and a tubular shape, wherein wires crossed or folded at both ends are aligned in the axial direction. 2. The stent according to claim 1, wherein an X-ray opaque material is fixed to portions of the wires at the both ends which are aligned in the axial direction. 3. The stent according to claim 1, wherein the wires at both end portions are aligned in the axial direction to form a stranded wire and integrated. 4. The stent according to claim 1, wherein axially aligned portions of the wire at both ends are alternately shifted in the axial direction between adjacent ones. 5. The wire material at both ends is aligned in the axial direction,
5. A fixing device comprising a radiopaque material covered thereon and fixed thereto.
A stent according to any one of the preceding claims.