JPH1066729A - Luminal expanding indwelling implement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balloon expansion type stent excellent in flexibility and the shape holding property after indwelling by providing tubular bodies extending notches in the peripheral direction and having the dynamic characteristic that the primary diameter insertable into an organism lumen can be expanded to the secondary diameter larger than the primary diameter, or made of two different materials. SOLUTION: Two kinds of tubular bodies including tubular bodies 1, 3 and a tubular body 2 are provided, and they are connected so that the tubular body 2 at the center section is pinched by the tubular bodies 1, 3 located at both ends. The width of linear elements left by the notches of the tubular bodies 1, 3 is set wider than the width of a continuous linear element by the notch of the tubular body 2, and the tubular bodies 1, 3 are formed with the notches formed with a part of a circle or an ellipse. The tubular bodies 1, 3 have structures extended in the peripheral direction with the force stronger than that of the tubular body 2, or they are made of a material requiring high expanding force. Since a spiral notch is applied to the tubular body 2, the linear element has a continuous spiral structure, and the tubular body 2 has flexibility in the longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indwelling device for expanding a lumen for treating a stenosis of a living body lumen such as a blood vessel and a digestive tract, and more particularly, to an indwelling device which is disposed on a balloon of a balloon catheter. After being introduced percutaneously to the stenosis site of the lumen, it is placed in a state where the stenosis site is expanded by the expansion force of the balloon, and is used for lumen expansion for maintaining the patency of the lumen permanently or temporarily. It relates to an indwelling device.

[0002]

2. Description of the Related Art At present, various stents and implants as indwelling devices for lumen expansion have been proposed and put into practical use.
These can be broadly classified into self-expanding types, which use elastic materials for the luminal indwelling device and expand the stenosis site with their own elastic force, and stents or implants themselves which have an expanding force. Instead, a balloon expandable type that is mounted on a balloon catheter and expands the stenosis site with the expansion force of the balloon.
Further, there are three types of shape memory type in which a stenosis site is expanded by body temperature or hot water using a shape memory material for the indwelling device for lumen expansion.

As a self-expanding stent, for example, Japanese Patent Application Laid-Open No. Sho 59-500652 discloses a tubular stent having an elastic wire formed in a mesh shape. A stent having a tubular structure in which an elastic wire is formed in a zigzag structure is disclosed. This is stored in a contracted state in the catheter,
It is expanded by pushing it out of the catheter inserted into the target site, and retains the lumen of the lumen. However, since the stent itself has an expanding force and keeps stimulating the lumen wall even after placement, especially when used in the circulatory system, the stimulus causes overgrowth of cells and leads to restenosis. There is a problem. Further, it is structurally very difficult to produce a self-expanding stent having an extremely small inner diameter of about 2 to 2.5 mm, and there is no stent that can be used for a thin blood vessel such as a coronary artery. Furthermore, this has the disadvantage that positioning in the target lumen is difficult due to the longitudinal contraction that occurs during self-expansion.

[0004] JP-A-3-9745, JP-B-6-2
Japanese Patent No. 6578 discloses a stent using a shape memory material. However, due to the drawback of the low elasticity of the shape memory material itself and the extremely low expansion force, those having satisfactory performance have not been completed.
In addition, since this is expanded by heat, the heat required for expansion may affect blood and tissues around the stent and cause thrombus formation and burns.

[0005] A balloon-expandable stent is expanded by inserting a balloon catheter having a stent mounted on a balloon into a target site and inflating the balloon. This is less structurally limited than a self-expanding stent, and can be made much smaller. The deployment of the balloon-expandable stent can be performed by the same operation as percutaneous transluminal coronary angioplasty; PTCA, and does not require special skill in surgical procedures. After inflation with a balloon, the deployed stent maintains its shape to prevent stenosis and occlusion. Due to its structure, unlike a self-expanding stent, it does not continue to press and stimulate the lumen wall, and does not cause overgrowth of cells, which is a problem with self-expanding stents. For this reason,
This is particularly preferably used as a circulatory stent.

A disadvantage of the balloon-expandable type is that the delivery system becomes thicker than the self-expandable type because the stent is mounted on the balloon during delivery. However, due to recent advances in balloon catheter formation technology, micro-balloon catheters with very small diameter balloons before expansion have also been developed.
The above problems have been eliminated.

As a balloon-expandable stent, for example, Japanese Patent Application Laid-Open No. 62-231657 discloses a stent having an opening formed in a cylinder so that a plurality of elongated members intersect. In this device, a ladder-like member left after a number of square openings are formed in a cylinder is used as a stent, and the square opening is expanded by a balloon to expand the stent. However, although this stent has excellent shape stability after expansion, it is inflexible in the longitudinal direction and cannot pass through a bent lumen,
It is difficult to place in a curved lumen, and if the lumen is bent after placement, the stent cannot follow the flexible movement of the lumen, which may damage the lumen wall.

Japanese Patent Application Laid-Open No. 1-145076 discloses a balloon-expandable stent in which a wire obtained by bending a wire in a snake shape is spirally formed. Although this stent is very flexible, it has two problems because it is formed from a single continuous wire and is helically wound over its entire length. One is that when the balloon is inflated, it does not expand uniformly, but becomes distorted due to uneven expansion. That is, in this device, the circumferential force generated during expansion escapes in the spiral direction formed by the wire, and the snake-shaped wire cannot be uniformly and sufficiently extended over the entire length of the stent. This phenomenon appears remarkably at both ends. That is, since the central portion of the stent is difficult to expand, it expands so as to escape from both ends to the central portion, and the central portion is deformed into an unexpanded gourd shape. If the stenosis is expanded in such a distorted shape, there is a possibility that the entire stenosis site cannot be expanded.

Another problem is that the stent has a weak retention force after expansion due to the structure of the stent, and suppresses the danger of the stent contracting due to the pressure on the lumen wall after the stent is placed and the overgrowth of cells. There is a risk of restenosis due to failure.

[0010]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in order to solve the above-mentioned conventional problems, and has a flexibility which can be suitably used for obstructive lesions of the circulatory system. It is an object of the present invention to provide a balloon-expandable stent having excellent shape retention after placement.

[0011]

That is, the present invention has a notch, and extends from the primary diameter which can be inserted into the lumen of a living body by extending the notch in the circumferential direction to a diameter larger than the primary diameter. Consisting of at least two tubular bodies having different mechanical properties or materials capable of being expanded to the next diameter, the tubular bodies being arranged in a cylindrical shape, and adjacent tubular bodies being connected at at least one point. The indwelling device for expanding a lumen is provided.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail using embodiments. FIG. 1A is a view showing a lumen expanding indwelling device according to an embodiment of the present invention, and FIG. 1B is a developed view thereof. The stent (5) is a combination of two types of tubular bodies, tubular bodies (1) and (3) and a tubular body (2), and the tubular body (2) is replaced by the tubular bodies (1) and (3). It is connected in a sandwiching manner. The width of the remaining linear element due to the notch in the tubular bodies (1) and (3) is wider than the width of one continuous linear element due to the notch in the tubular body (2). ),
(3) is formed of a notch formed by a part of a circle or an ellipse, and has a structure in which rigidity in the circumferential direction is stronger than that of the tubular body (2).

According to the present invention, the tubular bodies (1) and (3) located at both ends among the tubular bodies (1), (2) and (3) constituting the stent depending on the use site are tubular located at the center. A tubular body having a structure that does not extend in the circumferential direction unless a stronger force is applied than the body (2) or a tubular body made of a material requiring a high expansion force is arranged. Conversely, it is preferable that the tubular body located at the center of the stent be configured to expand in the circumferential direction with a smaller force than the tubular bodies located at both ends. Conversely, when the tubular body located at both ends of the stent has a structure that expands with a smaller force than the tubular body provided with a spiral cutout located at the center, when expanding with a balloon, It is not preferable because the central portion is deformed into an unexpanded gourd shape for expansion, and the entire stenosis site cannot be expanded.

The tubular body (2) is provided with a spiral notch to form a continuous spiral structure with one linear element, thereby obtaining flexibility in the longitudinal direction. If the tubular body (2) located at the center of the stent has a flexible structure, it is advantageous to obtain flexibility in the longitudinal direction. In order to impart flexibility to the tubular body (2), it is preferable to provide a spiral cutout in the tubular body, such as a structure in which a pattern depicting an S-shaped curve is spirally cut out. However, the design of the tubular body (2) is one embodiment of the present invention, and the present invention is not limited to this shape alone. By arranging and connecting the tubular body having the structure described above at the center of the stent, the flexibility in the longitudinal direction of the stent can be obtained without impairing the shape stability when the stent is expanded.

[0015] By these combinations, when the balloon catheter is expanded, the stent prevents the stent from expanding from both ends, so that the tubular body (1) has a relatively high rigidity structure.
(3) makes it possible to stabilize the shape after expansion, and is a lumen expansion indwelling device provided with a tubular body (2) that is flexible in the longitudinal direction.

The number of the tubular bodies constituting the stent according to the present invention is at least three, and the tubular body arranged at the center compared with the tubular bodies at both ends is characterized by placing an object having a small force required for expansion. one of. The expansion balloon starts to expand from both ends where the stent is not mounted because the stent mounted on the balloon is placed at the center of the stent. It is possible to eliminate the need to extend from a section.

Although the total length of the stent can be adjusted by changing the length of each tubular body, it can be easily adjusted by increasing the number of tubular bodies, and new advantages can be obtained. When the length of the tubular body having a flexible structure as shown in (2) of FIG. 1A is increased, the holding force after expansion is weakened, and the stent may contract due to the pressure on the lumen wall after placement. There is a danger that restenosis may occur due to inadequate control of cell overgrowth. According to the present invention, there is provided a stent having a structure in which the tubular body (1) and the tubular body (2) of FIG. 1A are alternately connected when the stent is to be placed in such a long curved lumen. It is possible to solve the problem.

Although there is no particular limitation on the method of connecting the tubular bodies, there are, for example, laser welding, adhesion, and a method of hooking and connecting the tubular bodies. The stent according to the present invention can also be realized by cutting the tubular member by laser processing. In order for the tubular body constituting the indwelling device for lumen expansion according to the present invention to expand in the circumferential direction, the tubular body needs to have a notch. The widening of the notch or crack widens the entire tubular body in the circumferential direction.

Here, it is preferable that the portion deformed when the notch or the crack is expanded is formed by a part of a circle or an ellipse having no corner. If all the notches are composed of straight lines, there is a corner at the intersection of the straight lines,
When the deformed portion undulates during expansion, the corners become projections on the surface of the tubular body and bite into the lumen wall, which may cause a serious situation such as lumen wall damage or pressure necrosis of the ulcer. It is not preferable because it also damages the balloon surface and increases the risk of balloon rupture. The material of the indwelling device for lumen expansion of the present invention is not particularly limited, and metals such as gold, platinum, silver, tantalum, stainless steel, and titanium, and all resins such as polypropylene, polyester, and tetrafluoroethylene can be used. is there. Further, the above metal can be coated with a resin for use. Further, in order to enhance antithrombotic properties and biocompatibility, a material to which an anticoagulant such as heparin or ticlopidine is fixed, or a substance stable in the living body such as polyparaxylylene may be coated.

[0020]

According to the present invention, there is provided a lumen expansion indwelling device in which at least three or more tubular bodies expandable from a primary diameter to a secondary diameter larger than the primary diameter are connected in the longitudinal direction. By changing the characteristics of the tubular body in various ways, it is possible to obtain a lumen expansion indwelling device having excellent circumferential shape stability and longitudinal flexibility. In addition, from the combination of the tubular body constituting the lumen expansion indwelling device,
When the balloon catheter is indwelled in a lumen using a balloon catheter, it is possible to produce a lumen expansion indwelling device that can prevent unbalanced deformation and securely indwell.

[Brief description of the drawings]

FIG. 1 is a view of a stent in which a plurality of tubular bodies having respective characteristics are combined according to an embodiment of the present invention.
(A) is a side view of the stent, and (b) is a developed view of the stent. As shown in FIG. 1A, the tubular bodies (1) and (3) consist of notches formed by a part of a circle or an ellipse, and the tubular body (2) has a flexibility in the longitudinal direction due to a spiral structure. I have. FIG. 1 (b) is an exploded view of the stent (5). The tubular bodies (1) and (3) at both ends are directed in the circumferential direction unless the force is stronger than the tubular body (2) located at the center. The structure does not expand and deform.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tubular body 2 Tubular body 3 Tubular body 4 Connecting part 5 Stent

Claims (4)

[Claims] At least one notch having a notch and extending from a primary diameter insertable into a lumen of a living body to a secondary diameter larger than the primary diameter by extending the notch in a circumferential direction. A lumen expansion indwelling device comprising three tubular bodies, wherein the tubular bodies are arranged in series in a cylindrical shape, and adjacent tubular bodies are connected to each other at at least one location. 2. The indwelling device for expanding a lumen according to claim 1, wherein a highly flexible tubular body is disposed between the highly rigid tubular bodies. 3. The indwelling device according to claim 1, wherein flexibility and rigidity are adjusted by changing the width of the linear element of the tubular body. 4. The indwelling device for lumen expansion according to claim 1, wherein at least a part of the notch is formed as a part of a circle or an ellipse.