JP2003250906A - Stent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stent which has a dilation force, facilitates contraction while well following up a curved blood vessel, is less changed in the length during the dilation and contraction, and can pressure evenly to the blood vessel during the dilation. <P>SOLUTION: The substantially cylindrical stent 10 for dilating and holding the constricted segments and closed segments of the blood vessels, bile ducts, tracheas, etc., of vascular segments of the living organism has a plurality of main body portions 1 and 2 which are arranged in the axial direction of the cylinder along the prescribed cylinder and extend in the circumferential direction of the cylinder and a plurality of straight and curvilinear joined portions 3 which exist between the adjacent portions of a plurality of the main body portions 1 and 2 and tie up these portions to each other, in which each of a plurality of the main body portions 1 and 2 has a zigzag shape consisting of straight lines or curves having the amplitude in the axial direction of the cylinder and grid shapes are formed by the portions adjacent to each other of the main body portions 1 and 2 and the joined portions 3 for tying up these portions to each other. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stent as a prosthesis, and more particularly to a device which can be easily inserted into a predetermined position and can be surely prosthesed.

[0002]

2. Description of the Related Art In recent years, treatment of stenosis and obstruction of blood vessels and trachea, and intravascular aneurysms is often performed by percutaneous minimally invasive medical surgery.

The above-mentioned treatment of stenosis / occlusion of blood vessels and trachea is
After guiding the catheter containing the balloon and the stent at the tip to the treatment area from the femoral artery or the mouth, release the balloon and the stent from the catheter by hand operation,
A stent is placed to expand the stenosis / occlusion by the balloon and hold the expanded diameter.

On the other hand, as for the aneurysm generated in the blood vessel, the blood flow to the aneurysm is stopped by embolizing the aneurysm generation portion with the stent by operating the catheter in the same manner as described above.

Conventionally, the shape of the stent is shown in FIG.
Mesh-like / lattice-like as shown in (a), (b) and (c)
Those in which zigzag shapes are connected have been proposed.

In the case of the stents 51, 52, 53 made of tantalum or stainless wire 50, the stent is inserted into the outer tube of the double-tube catheter by being wound around a balloon and reduced in diameter, and then introduced into the body. After releasing the stent and the balloon, the stenosis and the like are expanded with the balloon, and at the same time, the stent is expanded to the original diameter. Alternatively, there is also a type in which the stainless wire 50 or the like is formed in a zigzag shape to form a cylinder, and the pantograph is folded to reduce its diameter, and at the same time as the constraint is released from the catheter, the shape is restored to the original diameter by spontaneous spring force.

Further, a stent made of a shape memory alloy and having superelasticity to give more spontaneous shape recovery has been recently developed. With superelasticity, a cylindrical stent is folded into a small size and the diameter is constrained and reduced between the inner and outer tubes of a double-tube catheter. Let In addition, a stent in which a cylindrical shape is provided by cutting out a shape memory alloy sheet into a lattice shape has also been devised.

[0008]

Generally, the above-mentioned stents satisfy the expansion force, and various types of stents have been conventionally proposed.

However, when such a stent is used for a curved portion of a curved blood vessel, these mesh-like, lattice-like, and
In the cylindrical shape constructed in a zigzag shape or the like, the circular shape gradually becomes an ellipse as the curvature is reduced, and finally the cylinder cannot be maintained and it is crushed. Therefore, the function of expanding a blood vessel or the like cannot be fulfilled.

On the other hand, in order to carry the stent to the affected area, it is necessary that it can be inserted into a catheter having an inner diameter of about 2 mm and easily contract. The shape of the lattice, zigzag, etc. can be easily reduced. However, there is a drawback that the cylinder length when expanded and the length when contracted are greatly different. This makes it difficult to position the stent in the optimum portion during indwelling surgery.

Proposals for these measures have also been made. Specifically, as shown in FIG. 4, a separation portion 54a is formed by separating a part of the lattice shape, and a stent having a shape in consideration of the distance of the separated lattice or a wave as shown in FIG. For example, a stent in which a cutout portion 56 in which the number of connecting portions 57 having a zigzag shape or a zigzag shape is reduced is formed and the size of a wave-shaped or zigzag-shaped space is considered. However, these impair the portion that does not come into contact with the blood vessel wall and cause a large amount of pressure on the blood vessel in the stent.

Concrete examples of conventional stents, FIGS. 4 and 5, will be given.

Portions 54b and 56 of FIGS. 4 and 5 produce no pressure on the blood vessel. The portions 54a and 57 exert a large amount of pressure on the blood vessel due to the fact that there is nothing else to apply pressure to the blood vessel in the vicinity and the relatively sharp shape. These can cause vascular damage. From this point, it is desirable that the lattice shape is formed continuously.

Since the above three items are contradictory, it is difficult to combine them to a high degree.

Therefore, the general technical problems of the present invention are as follows.
An object of the present invention is to provide a new stent that solves this problem.

Further, a special technical problem of the present invention is that the blood vessel contracts while following a curved blood vessel having an expanding force. It is an object of the present invention to provide a stent that is easy to perform, has a small change in the lengths of the dilation and contraction, and can uniformly apply pressure to the blood vessel in the dilation.

[0017]

According to the present invention, a substantially cylindrical stent for expanding and holding a narrowed portion or a closed portion such as a blood vessel, a bile duct, a trachea of a tubular portion of a living body is formed into a predetermined cylinder. A plurality of main body portions that are arranged along the axial direction of the cylinder and extend in the circumferential direction of the cylinder, and a plurality of linear and curved connecting portions that connect these to each other between adjacent main body portions of the plurality of main body portions. However, each of the plurality of main body parts has a zigzag shape consisting of a straight line or a straight line and a curve having an amplitude in the cylindrical axis direction, and the adjacent main body parts and the connecting parts that connect them have a lattice shape. A stent is obtained which is characterized in that

Further, according to the present invention, in the stent, there can be obtained a stent characterized in that each of the plurality of connecting portions is connected to the main body portion while avoiding an apex portion of the main body portion.

Further, according to the present invention, in any one of the above-mentioned stents, a stent is obtained which is characterized in that the lattice shape is formed continuously in the circumferential direction and in the axial direction without loss.

Further, according to the present invention, in any one of the above-mentioned stents, a stent characterized in that the lattice shape is a straight line or a shape consisting of straight lines and curved lines can be obtained.

Further, according to the present invention, in any one of the above-mentioned stents, in a reduced diameter for mounting on a catheter, a lattice shape is formed by adjacent ones of the main body portions and the connecting portions connecting them. A stent is obtained which is characterized by not forming.

Furthermore, according to the present invention, in any one of the above-mentioned stents, at least a living body temperature (37 ° C.)
A stent is obtained which is characterized by being made of a TiNi-based shape memory alloy that exhibits superelasticity in the vicinity.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the drawings. Here, in the embodiment of the present invention, a stent having a relatively large diameter for the aorta of the chest and abdomen will be described as an example.

FIG. 1 (a) is a diagram showing a state in which a stent according to an embodiment of the present invention is in a flat shape when contracted, and FIG. 1 (b) is a partially enlarged view of (a). Is.
As shown in FIGS. 1 (a) and 1 (b), the zigzag-shaped main body 1 and main body 2 arranged in the axial direction of the stent along a predetermined cylinder and extending in the circumferential direction of the cylinder are curved at their apexes. It is formed by relaxing the strain due to expansion and contraction and connecting them with a straight line to have a zigzag shape. The connecting portions 3 which connect the adjacent main bodies to each other form a curved line mainly as a straight line and are arranged so as not to be one body as shown in FIG. 4A. Connected with. At the time of contraction, the main body parts 1 and 2 and the connecting part 3 do not form a lattice shape.

FIG. 2 (a) is a view showing a state where the expanded shape of the stent of FIGS. 1 (a) and 1 (b) is developed on a plane, and FIG. 2 (b) partially shows (a). FIG.
Here, in FIG. 2A, the upper and lower widths correspond to the length of the circumference when expanded. The left and right lengths correspond to the length of the stent and can be designed arbitrarily. 2 (a) and (b)
As shown in FIG. 4, in the stent according to the embodiment of the present invention, a rhombus-shaped lattice is continuously formed by the main body portion 2, the same main body portion 2 adjacent to the main body portion 1, and the connecting portion 3.

In this shape, the vertices 4 of the zigzag-shaped main body are not directly joined, but since there is the connecting portion 3,
4 and 5, there is no portion that does not come into contact with the blood vessel wall as shown in the portions 54a and 56 of the stent, and it is possible to uniformly apply pressure to the blood vessel within the stent.

Further, the stent according to the embodiment of the present invention is 1
Even if it was bent by 80 degrees, it was difficult for the cylindrical shape to completely collapse, and a space was secured inside the cylinder. Unlike the simple rhombic lattice shown in FIG. 3 of the related art, the stent according to the embodiment of the present invention does not directly join the apexes 4 of the main body. Therefore, when the stent is bent or curved, the main body It is possible for the spacing of the vertices 4 of V to vary. In addition, these improve the difficulty of collapsing the cylindrical shape.

Next, a concrete production of the stent according to the embodiment of the present invention will be described.

First, the specific dimensions and shape of the stent will be described. The main body parts 1 and 2 are, as shown in FIGS.
The zigzag shape has 6 vertices in the circumferential direction, the radial length is 6.28 mm, which is the circumferential length of φ2, and the length in the left-right direction of the zigzag shape, that is, the axial direction of the stent cylinder is 3.1.
It was set to 7 mm. Furthermore, 16 main bodies 1 and 2 were arranged alternately at intervals of 3,51 mm in the axial direction of the stent. The axially main components were displaced in the radial direction by 0.35 mm, and were arranged such that every other main body had the same radial position. This is to facilitate the formation of the rhombic lattice upon expansion. The total length of the stent was 54.8 mm. These main body parts 1 and 2 were connected by a connecting part 3 as shown in FIGS. 1 (a) and 1 (b).

In the embodiment of the present invention, the wall thickness is 150 μm.
After obtaining a TiNi alloy processed into a pipe shape with an outer diameter of 2 mm, the pipe surface is irradiated with Nd: YAG laser light while rotating the pipe, and the pipe is cut, as shown in FIGS. 1 (a) and 1 (b). The shape was made. During the laser processing, the line widths of the main body parts 1 and 2 and the connecting part 3 were set to 0.16 mm. After the laser processing, the oxide film on the TiNi pipe and burrs and melts generated during the laser processing were removed and chamfered by etching with hydrofluoric acid and electrolytic polishing.

Thereafter, expansion restraint was applied to the outside of the solid rod having a diameter of 8.4 mm, and the restraint state was maintained at 500 in an argon atmosphere.
Heat treatment at ℃ for 10 to 20 minutes and fix the shape at the same time as 37
It gave superelasticity at ° C. With the constraint released, a stent having an outer shape of 8 mm and a length of 49 mm having the shape of FIG. 2 was obtained.

The shape of the lattice when the main body parts 1 and 2 and the connecting part 3 are expanded is not limited to the embodiment of the present invention, and the number of zigzag-shaped vertices of the main body part, the length, and the axial direction. By changing the spacing, the expansion force, kink resistance, and bending load during bending can be changed. Further, the entire main body may be formed by only a straight line, or the apex portion may be formed by a straight line and the other portion may have a curvature.

In the embodiment of the present invention, TiNi is used.
The method of processing the pipe by laser was adopted, but TiN
It is also possible to form a stent shape on the i-sheet by laser or etching, and then weld it into a cylindrical shape.

The alloy used in the present invention is TiNiX which can have superelasticity at a living body temperature (for example, 37 ° C.).
An alloy is desirable, a TiNiX alloy with a third element added,
(X = Cr, V, Fe, Co, etc.) is preferable, but Fe
It is also applied to various shape memory alloys such as a system and alloys such as beta-Ti alloy, stainless steel, tantalum or other biological metals.

Further, in consideration of biocompatibility or toxicity, titanium or the like may be coated on the stent of the present invention.

[0036]

As described above, according to the present invention,
It has a sufficient expansion force, good bending characteristics, that is, it does not collapse even if it is used for the curved part of a curved blood vessel, and it has an easy contraction that can be inserted into the catheter. It is possible to provide a stent having a lattice-like shape in which the change in length upon expansion is small, and the number of portions that do not contact the blood vessel wall is small and pressure can be uniformly applied to the inner wall of the blood vessel.

[Brief description of drawings]

FIG. 1A is a diagram in which a shape of a stent according to an embodiment of the present invention when contracted is developed on a plane. (B) is a partial enlarged view of the stent of (a).

FIG. 2 is a plan view of the expanded shape of the stent according to the embodiment of the present invention.

FIG. 3 is a view showing a conventional stent shape.

FIG. 4 is a view showing a conventional stent having improved kink resistance and difference in length between expansion and contraction.

FIG. 5 is a view showing a conventional stent having improved kink resistance and difference in length between expansion and contraction.

[Explanation of symbols]

1, 2 main part 3 joints 4 Zigzag-shaped apex 10,51,51 ', 52,53,55 stent 50 stainless wire

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirotaka Asawaka             3-2-1 Nishi-Nakada, Taihaku-ku, Sendai City, Miyagi Prefecture               Maruki Medical Instruments Co., Ltd. (72) Inventor Tadashi Ishibashi             1-1 Seiryo-cho, Aoba-ku, Sendai City, Miyagi Prefecture (72) Inventor Hiroshi Nashihara             2-10-21 Kabira, Aoba-ku, Sendai City, Miyagi Prefecture F-term (reference) 4C167 AA44 AA53 AA55 BB31 BB40                       BB47 CC09 CC21 CC22 DD01                       FF05 GG24 GG32 GG33 HH01                       HH18

Claims (6)

[Claims] 1. A substantially cylindrical stent for expanding and holding a narrowed part or a closed part such as a blood vessel, a bile duct, a trachea of a tubular part of a living body, the stent being arranged along a predetermined cylinder in an axial direction of the cylinder. A plurality of main body portions extending in the cylindrical circumferential direction and between adjacent main body portions of the plurality of main body portions, and having a plurality of straight and curved connecting portions connecting these to each other, each of the plurality of main body portions A stent having a zigzag shape composed of a straight line having an amplitude in the cylindrical axis direction or a straight line and a curved line, and forming a lattice shape by adjacent ones of the main body portions and the connecting portions connecting them. 2. The stent according to claim 1, wherein each of the plurality of connecting portions is connected to the main body portion while avoiding an apex portion of the main body portion. 3. The stent according to claim 1 or 2, wherein the lattice shape is formed continuously without being damaged in the circumferential direction and the axial direction. 4. The stent according to any one of claims 1 to 3, wherein the lattice shape is a straight line or a shape composed of straight lines and curved lines. 5. The stent according to any one of claims 1 to 4, wherein in a reduced diameter to be mounted on a catheter, the main body portions are adjacent to each other and the connecting portion connects them. A stent characterized by not forming a lattice shape by and. 6. The stent according to claim 1, wherein the stent is made of a TiNi-based shape memory alloy that exhibits superelasticity at least near a living body temperature (37 ° C.).