JPH1199208A - Stent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the obtaining of a desired rigidity and a localization, and prevent a positional slip at a self-retaining region from arising by a method wherein a grille-forming beam to form a grille at the time of diameter contraction is formed into a flat shape which goes along a grille-form cylindrical, surface, and the grille- forming beam is formed in such a manner that the grille-forming beam may be cut- erect-crossed to the cylindrical surface. SOLUTION: A TiNi alloy sheet which is a shape-memory alloy sheet, is cut-worked and formed into a grille-shape, and a beam of the grille is formed into a flat surface- shape. Then, the sheet is rolled into a cylindrical shape of a first diameter D1 and retained to make a first cylinder 1, and after mechanically expanding the cylinder to a cylinder of a second diameter, a heat-treated and fixed second cylinder is formed. In this case, the first cylinder 1 of the first diameter D1 becomes the dimension with a contracted diameter of this stent which is housed in a catheter, and the second cylinder of the second diameter is made slightly larger than the internal diameter of an indwelling region or a windpipe. The stent which is diameter-contracted in icy water is restored to the original diameter by expanding a baloon at a constriction region, and at the same time, a blood vessel expansion and the expansion-retaining are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art It is well known that a shape memory alloy such as a TiNi alloy exhibits a remarkable shape memory effect and superelasticity accompanying a reverse transformation of martensitic transformation.
Above all, TiNi alloy has excellent functions near the living environment temperature, so actuators for household appliances such as microwave oven damper, air conditioner air direction control, rice cooker steam pressure regulating valve, etc.
It is used in a wide range of fields, such as ventilation openings for architecture, antennas for mobile phones, and eyeglass frames. Attempts to apply it to the medical field have been made since the beginning of alloy development, and orthodontics, artificial dental roots, vascular dilatation coils, catheter guide wires, and the like have been put to practical use.

In recent years, stenosis and occlusion of blood vessels and trachea and endovascular aneurysms are often treated by percutaneous minimally invasive medical surgery. For treatment of stenosis and occlusion of blood vessels and trachea, a catheter containing a balloon and a stent at its distal end is guided to the treatment site through the femoral artery or mouth, and then the balloon and stent are released from the catheter by manual operation. A stent is deployed to expand the stenosis / occlusion with a balloon and maintain the expanded diameter. On the other hand, in the case of an aneurysm generated in a blood vessel, blood flow to the aneurysm is stopped by embolizing the cancer-causing site with a stent by operating a catheter as described above.

[0004] In the case of a mesh-like or lattice-like stainless steel stent, the stent is wound around the inner tube of a double-lumen catheter, and is advanced into the body in a state of reduced diameter. After releasing the stent and balloon from the outer tube at a predetermined site, the balloon is used. At the same time as the stenosis is expanded, the stent is expanded to its original diameter. Alternatively, there is a type in which a stainless steel wire is formed in a zigzag shape to form a cylinder, the diameter of the cylinder is reduced by folding the bantagraph, and the original diameter is restored by spontaneous spring force simultaneously with release of restraint from the catheter.

Further, a stent having a spontaneous shape recovery force by using a stent made of a shape memory alloy has been recently developed. Among them, the one utilizing the shape memory effect, the stent reduced in diameter with cold water is continuously cooled with cold air or cold water even when introduced into the body, and the shape is restored to the original diameter at body temperature during the expansion operation. In addition, those using superelasticity have a reduced diameter by extending the helical coil of the wire, or a small meshed cylinder that is constricted between the inner and outer tubes of a double-tube catheter, At the same time as the release of the restraint.

[0006]

However, in the case of a stainless steel stent, the rigidity of the cylinder that constitutes the stent must be sufficiently low because the catheter must have a storage property and expandability with a balloon. The rigidity at the time of restoring the original diameter for preventing restenosis, which is required in a conventional manner, has a disadvantage that it cannot be said that the rigidity is sufficient. In the case of a stent that uses the shape memory effect of a shape memory alloy and recovers its shape at body temperature, there is a technical problem in maintaining cooling and transporting the stent to a predetermined site. In the case of recovering the shape at a temperature exceeding the body temperature, there are difficulties in a heating method for shape recovery at a predetermined site and a decrease in the rigidity of the stent due to a decrease in the ambient temperature until the body temperature at the time of placement. Here, generally, the shape memory alloy becomes extremely soft in the martensite phase. Therefore, a stent using a shape memory alloy that exhibits superelasticity at body temperature has the best shape retention, but the conventional structure has problems in its storage properties and gripping force when expanded.

That is, in the case of a coil spring, the diameter of the stent can be reduced by pulling the coil, but the length of the deformed stent in the axial direction becomes longer, and it is difficult to store the stent in the catheter and to position it in the indwelling site. Has disadvantages.

[0008] On the other hand, in the case of a mesh or lattice, the cylindrical processed product of the plate is squeezed in a spiral shape to reduce the diameter, and after release, the lattice constituting the cylinder is reduced when the diameter is reduced. At the time of expansion, both are parallel to the outer peripheral surface of the cylindrical tube, and when used, there is little biting into the inner wall of the expanded portion.

Accordingly, one technical object of the present invention is to provide a stent which has desired rigidity and easy positioning.

[0010] Another technical object of the present invention is to provide a stent that can prevent displacement at an indwelling site.

[0011]

According to the present invention, there is provided a stent for expanding and holding a stenosis or obstruction such as a blood vessel or a trachea or for embolizing an aneurysm in a blood vessel. The lattice-forming beam that forms the lattice when the diameter is reduced has a flat shape substantially along the circumferential surface. When the original shape is restored, the lattice-forming beam cuts and intersects with the cylindrical surface. A stent characterized by being formed is obtained. That is, in the present invention, a stent for expanding and holding a stenosis or obstruction such as a blood vessel or a trachea or an aneurysm embolization stent in a blood vessel is substantially formed by a cylindrical lattice forming beam when the diameter is reduced. The flat shape makes it easy to store in the catheter, and when restoring the original shape, the lattice forming beam is deformed so as to stand up against the cylindrical surface to increase the bite into the inner wall of the required site and prevent displacement during use. Is what you do.

Further, according to the present invention, in the stent, there is obtained a stent in which the cylinder is a bifurcated branching partway, and at least a part thereof is connected without a seam. That is, in the present invention, the bifurcated stent is configured to prevent the displacement of the stent during use, and by making at least a part of this cylinder seamless, the stent does not break off during use. It is intended to provide a stent with improved safety.

Further, according to the present invention, there is provided the above-mentioned stent, wherein at least one bifurcated cylinder has a cut. That is, in the present invention, by providing a cut in at least one of the bifurcated cylinders, a stent that can be easily reduced in diameter and introduced into the body can be provided.

Further, according to the present invention, in the stent according to any of the above, at least the biological temperature (about 37
(C) A stent characterized by being made of a TiNi-based shape memory alloy exhibiting superelasticity is obtained. That is, in the present invention, the stent is placed at least at the biological temperature (about 37 ° C.).
By using a TiNi-based shape memory alloy that exhibits superelasticity with
An object of the present invention is to provide a stent in which penetration into an inner wall at a predetermined site is further enhanced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of a lattice shape at the time of cutting in a shape memory alloy sheet according to an embodiment of the present invention. Referring to FIG. 1, a stent according to an embodiment of the present invention is formed of a cylinder obtained by processing a TiNi alloy sheet into a lattice shape, and a lattice beam 11 of the TiNi alloy sheet 10 has a planar structure and a width W thereof is reduced. The circumferential length at the time of diameter, and the length L is the length of the stent.

FIG. 2 is a perspective view of a first cylinder formed from the TiNi alloy sheet 10 of FIG. 1, and FIG. 3 is a TiNi of FIG.
FIG. 3 is a perspective view of a second cylinder formed from the alloy sheet 10.

As shown in FIGS. 2 and 3, the TiN of FIG.
The i-alloy sheet 10 is rounded and constrained to a cylindrical shape having a first diameter D1 to form a first cylinder 1, which is then mechanically expanded into a cylinder having a second diameter D2, and then heat-treated and fixed. 2 cylinder 2. Here, the first cylinder 1 having the first diameter D1
Indicates the diameter reduction dimension of the stent accommodated in the catheter, and the second cylinder 2 having the second diameter D2 is placed in the body or slightly larger than the inner diameter of the trachea.

(First Embodiment) In the first embodiment, a stent for coronary artery will be described as an example.

First, a 50 μm-thick TiNi alloy sheet was cut out in a lattice shape and was cylindrically constrained to a diameter of 1 mm to obtain a first cylinder 1 shown in FIG. Next, the mandrel is inserted and expanded to an inner diameter of 5 mm, and the lattice beam 11 is made substantially perpendicular to the circumference by expanding the diameter. Thereafter, heating was performed in a constrained state, and at the same time, superelasticity at 37 ° C. was imparted to the shape. Completed length 5m
m The cut of the cylinder of the second cylinder 2 was tied with a thread such as nylon to obtain a constrained cylinder stent.

FIG. 4 is a diagram showing a cross-sectional shape of the stent 3 for coronary artery when the catheter is housed, and FIG. 5 is a diagram showing a cross-sectional shape of the stent 3 for coronary artery after the restraint release when the inner wall of the blood vessel is placed. An example of using the coronary stent 3 will be described with reference to FIGS. The specific operation is shown in FIG.
As shown in Fig. 3, a stent 3 reduced in diameter to 1 mm in ice water
Is inserted between the catheter inner tube 4 and an outer tube (not shown) from the femoral artery to the stenosis site of the heart. Next, as shown in FIG. 5, the stent 5 is released from the catheter outer tube for restraining the stent to release the restraint of the stent 3 and the balloon 5 is inflated.
At the same time as restoring the original diameter, vasodilation and dilation maintenance are performed. Reference numeral 21 denotes a body wall of a stent placement site.

(Second Embodiment) In a second embodiment, a tracheal stent will be described.

A TiNi alloy sheet 10 having a thickness of 100 μm
Are cut out in a lattice shape to produce a first cylinder 1 having a diameter of 6 mm.
Thereafter, the tube was expanded and heat-treated to form a second cylinder 2 having a diameter of 20 mm. The manufacturing method is the same as that of the first embodiment.

Next, an example of use of the tracheal stent according to the second embodiment will be described. As a specific operation, a catheter containing the stent 3 reduced in diameter to 5 mm from the mouth is inserted to the tracheal stenosis site, and the indwelling operation is performed. The concept of the cross section of the tracheal stent at the time of the operation is the same as that shown in FIGS.

(Third Embodiment) In a third embodiment, a branched tracheal stent will be described. A problem when the stent is placed in the body is a temporal displacement due to an external load exerted on the stent such as blood flow and patient movement. It can be said that the stent of the present invention is an effective stent that solves this problem.
Placement of a bifurcated stent using branching of blood vessels and trachea near the affected area.

FIG. 6 is a view showing a shape memory alloy sheet for producing a branched tracheal stent according to the third embodiment. Referring to FIG. 6, a TiNi alloy sheet 12 obtained by cutting the TiNi alloy sheet 10 having the lattice beams shown in FIG. 1 as shown in FIG. 6 is obtained, a cylinder having a diameter of 5 mm is formed, and each cylinder is expanded to 20 mm. Then, heat treatment was performed to obtain one having the same performance as that of the second embodiment.

Next, as shown in FIG. 7, the cylinder attached to the inner wall of the treatment affected part is cut with a thread 13 to improve the bite into the wall, and the other forked cylinder 7 prevents the stent 6 from moving. Therefore, the cylindrical cut 8 is left so that it can be reduced to a cuvette shape in consideration of the storage property in the catheter.

Next, an example of use of the branched tracheal stent according to the third embodiment will be described. As a specific operation, a catheter containing a tracheal stent 6 reduced in diameter to 5 mm from the mouth is inserted to a tracheal stenosis site, and the indwelling operation is performed. The concept of the operation is the same as that shown in FIGS. 4 and 5 according to the first embodiment.

In the embodiment of the present invention, a TiNi alloy which can have superelasticity at a living body temperature is used. TiNiX alloy (X = Cr, V, Cu, Fe, C)
o) etc. can also be used and are preferred.
The present invention can also be applied to various kinds of alloys such as Fe-based shape memory alloys and beta Ti alloys.

The lattice pattern forming the cylinder of the stent is not limited to the embodiment of the present invention.
All the structures in which the beams of this lattice are flat when the diameter is reduced and orthogonal when the original diameter is restored are applied.

Further, the titanium may be coated with titanium or gold in consideration of biocompatibility or toxicity.

[0032]

As described above, according to the present invention,
A stent having desired rigidity and easy positioning can be provided.

Further, according to the present invention, it is possible to provide a stent capable of preventing displacement at an indwelling site.

[Brief description of the drawings]

FIG. 1 is a plan view of a shape memory alloy sheet constituting a stent according to an embodiment of the present invention.

FIG. 2 is a perspective view of a stent manufactured using the shape memory alloy sheet of FIG. 1 at the time of diameter reduction.

FIG. 3 is a perspective view of the stent of FIG. 2 when the original diameter is restored.

FIG. 4 is a cross-sectional view of the stent when housed in the catheter according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view of the stent of FIG.

FIG. 6 is a plan view of a shape memory alloy sheet constituting a stent according to a third embodiment of the present invention.

FIG. 7 is a perspective view showing a stent formed from the shape memory alloy sheet of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st cylinder 2 2nd cylinder 3 Stent for coronary artery 4 Inner catheter tube 5 Balloon 6 Stent 7 Bifurcated cylinder 8 Cut 10,12 TiNi alloy sheet 11 Lattice beam 13 Thread 21 Body wall of stent placement site

Claims (4)

[Claims] 1. A stent for expanding and holding a stenosis or obstruction such as a blood vessel or a trachea or for embolizing an aneurysm in a blood vessel, having a lattice-like cylindrical shape, and forming the lattice when the diameter is reduced. The lattice forming beam to be formed is a flat shape substantially along the cylindrical surface, and the lattice forming beam is formed so as to be cut and intersect with the cylindrical surface when the original shape is restored. 2. The stent according to claim 1, wherein the cylinder is a bifurcated branch that branches in the middle, and at least a part of the cylinder is connected seamlessly. 3. The stent according to claim 2, wherein at least one bifurcated cylinder has a cut. 4. The stent according to claim 1, wherein at least the biological temperature (about 37 ° C.)
1. A stent comprising a TiNi-based shape memory alloy showing superelasticity.