JP2004049806A - Stent and graft with stent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stent and a graft with the stent that can be diametrally easily contracted, have a sufficient expansive force, and reduce an application of a local compressive force to the inwall of a tubular organ even in a case where the stent is set in a curved position of the tubular organ. <P>SOLUTION: The stent 20 is formed into a cylinder by weaving metal wires 21 and has portions A crosswise intersecting and portions B each curved into a U shape in the net structure of the metal wires 21. The portions B each curved into the U shape are entangled with the crosswise intersecting portions A with the curved tip portions B1 directed outward. By covering the inside periphery and/or the outside periphery of the stent 20 with a cylindrical cover 30, the graft 30 with the stent is formed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stent and a graft with a stent to be inserted and placed in a tubular organ of a human body such as a blood vessel, a ureter, a bile duct, and a trachea.
[0002]
[Prior art]
In recent years, stents have been inserted and placed 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 arranged at a stenotic portion of a blood vessel to expand the stent, or a stent is arranged at a place where an aneurysm is formed to prevent rupture of the aneurysm. In particular, in the treatment of aneurysms, a stent-attached graft obtained by coating the outer periphery of a stent with a woven fabric called a graft is used.
[0003]
As a conventional stent, for example, Japanese Patent Application Laid-Open No. 11-57021 discloses that a predetermined number of filaments are twisted in a sine curve to form a cylindrical cage-shaped braided structure. A stent is disclosed in which the ends are formed into a loop structure by folding or joining the filaments, and each filament is an infinite loop having no ends as a whole.
[0004]
Japanese Patent No. 2975584 discloses a stent for expanding a body cavity comprising a single filament formed in a cylindrical shape having a large number of zigzag bands, and the band has a large number of linear portions, peak portions and valley portions. Wherein the peaks and valleys are disposed circumferentially on the stent and on the same plane, and the valleys forming the band have at least one and a half turns of the peak of the adjacent lower band. There is disclosed a stent for expanding a body cavity, wherein the stent is connected in a twisted manner as described above, and the filament of the adjacent lower band is a filament extending downward from a linear end portion of the adjacent upper band.
[0005]
[Problems to be solved by the invention]
These stents are transported to a predetermined position in a tubular organ of a human body while being mounted on the inner periphery of the distal end portion of the catheter, and are pushed out of the catheter there and are placed in the tubular organ. For this reason, when it is attached to the inner periphery of the distal end of the catheter, the diameter can be easily reduced, and when it is pushed out of the catheter, the tubular organ can be expanded with a sufficient expanding force, that is, elastic expansion. Power is required.
[0006]
However, when the stent is placed in a place where the tubular organ is bent, if the elastic expansion force of the stent is too strong, the force of the stent to return to a linear state is also increased. It is strongly pressed locally against the inner wall, which is not preferable.
[0007]
Therefore, an object of the present invention is to allow the diameter of the tubular organ to be easily reduced when mounted on the inner circumference of the catheter, and to expand the tubular organ with a sufficient expansion force when the tubular organ is pushed out from the catheter. An object of the present invention is to provide a stent and a graft with a stent in which local pressing force is reduced on the inner wall of the tubular organ even when the stent is placed at a bent portion of the organ.
[0008]
[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 into a cylindrical shape, wherein a cross-shaped portion and a U-shaped portion are formed in the knitted structure of the metal wire. A stent having a bent portion, wherein the U-shaped bent portion is entangled with the cross-shaped portion with the bent tip end directed toward the outer peripheral side. Things.
[0009]
In the above invention, the metal wire is knitted and formed into a cylindrical shape, and since there is a portion crossing in a cross shape in this knitted structure, sliding between the wires and variation in the crossing angle are easily performed, so that shrinkage occurs. The diameter of the tubular organ can be easily reduced when the catheter is mounted on the inner circumference of the catheter, and when expanded from the catheter, the tubular organ can be expanded with a sufficient expansion force.
[0010]
Further, the knitted structure further has a portion bent in a U-shape, and the portion bent in the U-shape is entangled with the portion crossed in the cross shape with the bent tip end toward the outer peripheral side. Therefore, when the stent is bent, the bent portion comes into contact with the crossed portion to apply a frictional force, and the bent shape can be easily maintained. That is, even when the tubular organ is arranged at a bent portion, the resilient force is reduced by adapting to the bent shape, so that the local pressing force applied to the inner wall of the tubular organ is reduced.
[0011]
Furthermore, when the stent is bent, the knitted tissue tends to shrink on the inner circumferential side of the bent portion, but at that time, the bent portion crosses in a cross shape with its distal end directed toward the outer circumferential side. Since it is entangled with the portion, the distal end portion may protrude to the outer peripheral side of the stent, but does not protrude to the inner peripheral side. For this reason, there is no fear that the blood flow flowing inside the stent is affected.
[0012]
According to a second aspect of the present invention, in the first aspect, the bent portion is formed by inserting a portion extending to both sides from the bent tip portion into an opposing lattice space of the cross-shaped portion from the outer peripheral side. To provide a stent that has been entangled.
[0013]
According to the above invention, the bent tip portion comes into contact with two of the wires extending in four directions from the cross-shaped intersection from the outer peripheral side, and the portions extending on both sides correspond to the remaining two of the wires extending in the four directions. Since the contact is made from the inner peripheral side, when the stent is bent, the frictional force acts more effectively, and the bent shape is easily maintained.
[0014]
According to a third aspect of the present invention, in the first or second aspect, a portion where the crossed portion and the bent portion are entangled is arranged in an annular or spiral shape along the circumferential direction. A stent is provided.
[0015]
According to the above invention, since the rigidity is imparted by the entangled portion along the circumferential direction, the expansion force in the radial direction of the stent is improved, and when the stent is bent in the axial direction, the stent is easily bent and entangled. The bent shape is easily maintained by the frictional force of the bent portion.
[0016]
A fourth aspect of the present invention is to provide a stent-attached graft including the stent according to any one of the first to third aspects of the present invention and a tubular cover that covers the inner periphery and / or the outer periphery of the stent.
[0017]
According to the above invention, for example, the blood flow can be disposed inside the aneurysm of a blood vessel to prevent the blood flow from flowing toward the aneurysm. In addition, when the stent is bent, even if the distal end of the U-shaped bent portion protrudes to the outer peripheral side, the outer periphery is covered by the cylindrical cover, so there is no risk of damaging the inner wall of the tubular organ.
[0018]
Note that the tubular cover can be fixed to a part or the whole of the stent by using a known fixing means such as sewing, adhesion, and welding. In particular, it is preferable that the tubular cover is fixed to the end of the stent of the present invention or at the vicinity of the end. Further, the tubular cover can cover a part or all of the outer periphery and / or the inner periphery of the stent, but is preferably attached so as to cover the outer periphery of the stent.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited only to these embodiments.
[0020]
1 to 5 show one embodiment of a graft with a stent according to the present invention. 1A and 1B show the stent-attached graft, wherein FIG. 1A is a perspective view of a stent used therein, FIG. 1B is a perspective view of the stent-attached graft with a cylindrical cover partially cut away, and FIG. FIG. 3 is a partially developed view showing a knitting pattern. FIG. 3 is an explanatory view showing a state in which the stent-attached graft is arranged inside an aneurysm of a blood vessel. FIG. 4 is an explanatory view showing stress when the stent-attached graft is bent. FIG. 5 is an explanatory diagram showing, in an enlarged manner, the outer and inner states of the portion where the wire is entangled when the graft with the stent is bent. FIG. 6 is an explanatory diagram showing, in an enlarged manner, the outer and inner states of the wire entangled portion when the stent in which the distal ends of the U-shaped bent portions are entangled is bent. It is.
[0021]
As shown in FIG. 1, the stent-attached graft 10 has a stent 20 formed by knitting a predetermined number of metal wires 21 into a mesh and a tubular shape, and a tubular cover 30 that covers the stent 20. I have.
[0022]
Referring also to FIG. 2, the stent 20 has, in its knitted structure, a portion A where the metal wires 21 cross in a cross shape and a portion B where the metal wires 21 are bent in a U-shape. The portion B bent in a U-shape is entangled with the portion A intersecting in the cross shape.
[0023]
In this case, the portion B bent in a U-shape is inserted from the outer periphery into the opposing lattice spaces C1 and C2 of the crossed portions in the portions B2 and B3 extending to both sides from the bent front end portion B1. Being entangled. The front side (paper side) in FIG. 2 forms the outer peripheral side of the stent 20.
[0024]
In this embodiment, the metal wires 21 are woven in a lattice pattern, and cross portions A are formed at predetermined intervals. A bent portion B is intertwined with some of the cross portions A. A portion D1 having a high mesh density and portions B2 and B3 extending on both sides of the bent portion B extend in the axial direction, and a low-mesh density portion D2 is formed in a ring shape along the circumferential direction, and the It is formed alternately in the direction.
[0025]
The high-density mesh portion D1 contributes to imparting an expanding force in the radial direction of the stent 20, and the low-density mesh portion D2 contributes to easily bending the stent 20 in the axial direction. .
[0026]
The tubular cover 30 covers the outer periphery of the stent 20, and is sewn to the stent 20 at both ends. The tubular cover 30 may be mounted so as to cover the inner circumference of the stent 20, may be mounted so as to cover both the inner circumference and the outer circumference, and may be further mounted so as to cover a part of the stent 20. However, preferably, the stent 20 is attached so as to cover the outer periphery of the stent 20.
[0027]
It is preferable that the intersection of the metal wires 21 is not fixed, thereby increasing the degree of freedom of displacement between the wires 21 and facilitating diameter reduction at the time of insertion of the catheter and expansion at the time of extrusion from the catheter. Can be. The portion where the ends of the metal wires 21 overlap with each other, or the portion where the ends of the metal wires 21 overlap with the metal wires 21 may be fixed with, for example, solder, metal brazing, an adhesive, or the like, or with a metal material or the like. You may squeeze.
[0028]
In addition, as a material of the metal wire 21, a shape memory alloy imparting a shape memory effect by heat treatment or superelasticity is preferably adopted, but depending on the use, stainless steel, tantalum, titanium, platinum, gold, tungsten, or the like is used. May be. As the 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 21 is not particularly limited. For example, in the case of a vascular stent or the like, the thickness is preferably 0.08 to 1 mm.
[0029]
The cylindrical cover 30 is formed by extruding a thermoplastic resin into a cylindrical shape by a molding method such as blow molding, a knitted fabric of fibers of a thermoplastic resin formed into a cylindrical shape, or a thermoplastic resin formed into a cylindrical shape. A nonwoven fabric, a sheet of a flexible resin formed in a cylindrical shape, a porous sheet, or the like can be used. Known knits or woven fabrics such as plain weave and twill weave can be used as the knitted fabric. Further, as the cylindrical cover 30, one with a crease such as crimping may be used. In addition, as the cylindrical cover 30, a cover provided with a hole on a side portion of the cover can be used.
[0030]
Among these, as the cylindrical cover 30, in particular, a knitted and woven fabric of a thermoplastic resin fiber formed in a cylindrical shape, and a plain woven woven fabric of a thermoplastic resin fiber formed in a cylindrical shape, have strength and porosity, It is preferable because of excellent productivity.
[0031]
Examples of the thermoplastic resin include polyolefins such as polyethylene, polypropylene, and ethylene-α-olefin copolymer, polyamides, polyurethanes, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polycyclohexane terephthalate, and polyethylene-2,6-naphthalate; A resin having low durability and a small tissue reaction, such as a fluororesin such as ethylene fluoride and polyfluorinated propylene, can be used.
[0032]
In particular, polyesters such as polyethylene terephthalate, and fluororesins such as polyfluoroethylene and polyfluoropropylene, which are chemically stable, have high durability, and have low tissue reaction, can be preferably used.
[0033]
The tubular cover 30 is sewn to both ends of the stent 20 in the above embodiment, but may be fixed by bonding, welding, or the like. In this case, it is necessary to select a place to be fixed to the stent 20 so as not to hinder the contraction and expansion of the diameter of the stent 20.
[0034]
As the tubular cover 30, the fibers constituting the cover, and the metal wires 21 constituting the stent 20, those coated with an antithrombotic material such as heparin, collagen, acetylsalicylic acid, gelatin, etc. can also be used. .
[0035]
Further, an X-ray opaque material may be fixed to an appropriate portion of the graft 10 with a stent, for example, at both ends. As the X-ray opaque material, for example, gold, platinum, iridium, tantalum, tungsten, silver, etc., and alloys containing them are preferably used. The radiopaque material can be fixed to the stent 20 by means of soldering, brazing, welding, bonding, caulking, or the like.
[0036]
Further, the graft 10 with a stent of the present invention thus obtained preferably has an outer diameter of 2 to 50 mm and a length of about 1 to 20 cm.
[0037]
Next, a method of using the graft 10 with a stent will be described. The stent-graft 10 can be applied to any part of a human tubular organ such as a blood vessel, a ureter, a bile duct, a bronchus, etc., but is particularly arranged inside an aneurysm of a blood vessel so that blood flows into the aneurysm. This is suitable for the treatment for preventing the rupture of the aneurysm.
[0038]
An example of a procedure for inserting a blood vessel into a blood vessel for treatment of an aneurysm will be described below. First, a guide wire is inserted into a blood vessel by a conventional method, and the distal end thereof is positioned at an affected part. Then, a parent catheter is inserted along the outer periphery of the guide wire, and when the distal end reaches a target portion, the guide wire is pulled out.
[0039]
Then, the diameter of the stent-attached graft 10 is reduced and inserted into the distal end of the child catheter. At this time, the cross section A of the stent 20 of the stent-attached graft 10 is reduced in diameter because the metal wires 21 are displaced relatively freely and the crossing angle can be changed relatively freely. It has the effect of making it easier.
[0040]
When the distal end of the child catheter reaches the affected part in this way, a pusher is inserted into the child catheter, and the graft 10 with a stent is pushed into the aneurysm A 'of the blood vessel A shown in FIG. Then, since the graft 10 with a stent is of a self-expanding type, its diameter is expanded by its own expanding force. As a result, both ends of the graft 10 with a stent are closely arranged on the inner periphery of both ends of the aneurysm A ′.
[0041]
At this time, since the stent 20 constituting the graft 10 with a stent is formed by knitting the metal wire 21 into a mesh shape and a tubular shape, the stent 20 naturally fits the bent shape of the blood vessel A, and has the same shape as the blood vessel A. Closely adheres to the inner circumference without gaps.
[0042]
As shown in FIG. 4, when the graft 10 with a stent is bent, a tensile force F1 acts on the outer peripheral side and a compressive force F2 acts on the inner peripheral side. As a result, as shown in FIG. 5, on the outer side O of the bent shape of the stent-attached graft 10, the distal end portion B1 of the bent portion B of the metal wire 21 engages with the portion A crossing in a cross shape. In the inside I of the bent shape of the stent-attached graft 10, the distal end portion B1 of the bent portion B protrudes outward with respect to the peripheral surface of the stent 20 away from the portion A crossing in a cross shape.
[0043]
However, since the outside of the stent 20 is covered with the cylindrical cover 30, even if the bent portion B of the metal wire 21 projects, there is no fear that the inner wall of the blood vessel A is damaged. In addition, since it does not protrude from the inner periphery of the stent 20, there is no risk of affecting the blood flow flowing inside.
[0044]
Further, the distal end portion B1 of the bent portion B of the metal wire 21 abuts from the outside on two of the four metal wires 21 extending radially from the portion A crossing in a cross shape, and is provided on both sides of the bent portion B. Since the extending portions B2 and B3 are in contact with the other two of the four metal wires 21 radially extending from the portion A intersecting in a cross shape, the frictional force between the metal wires 21 is effective. And it is easy to maintain the stent-attached graft 10 in a bent shape.
[0045]
FIG. 6 shows an example in which the distal end portions B1 of the bent portion B of the metal wire 21 are entangled for comparison. In such an example, in the bent outer portion O of the stent-attached graft, the distal end portions B1 of the bent portion B of the metal wire 21 are engaged with each other. Since the entanglement between the bent portions B of the wire 21 is loosened, their distal ends B1 project toward the inner peripheral side of the stent 20. For this reason, there is a possibility that a turbulent flow is caused in the blood flow flowing inside the stent, and a thrombus or the like is generated.
[0046]
FIG. 7 shows an example of an entangled shape in a knitted structure employed in the stent of the present invention.
[0047]
In the example shown in FIG. 3A, a portion B bent in a U-shape is formed by connecting portions B2 and B3 extending on both sides from the bent end portion B1 to the second row from the end of the region woven in a lattice shape. Are inserted and entangled from the outer peripheral side into the opposing lattice spaces C1 and C2 of the portion A2 crossing in a cross shape. The tip B1 abuts from the outside on the two wires 21a and 21b of the four wires extending radially from the intersecting portion A2, and the portions B2 and B3 extending on both sides are the four wires, The other two wires 21c and 21d are in contact with each other from the inside. Further, the portions B2 and B3 extending on both sides abut from outside on the wires 21e and 21f extending from the cross-shaped portion A1 located at the end of the region woven in a lattice shape. According to this entangled shape, the number of wires that come into contact with each other increases in the bent portion B of the wires 21, so that the frictional force between the wires 21 when the stent 20 is bent in the axial direction strongly acts, It becomes easier to maintain the shape.
[0048]
In the example shown in FIG. 2B, a portion B bent in a U-shape has portions B2 and B3 extending to both sides from the bent tip portion B1 in the second row from the end of the region woven in a lattice shape. Are inserted and entangled from the outer peripheral side into the opposing lattice spaces C1 and C2 of the portion A2 crossing in a cross shape. The tip B1 abuts from the outside on the two wires 21a and 21b of the four wires extending radially from the intersecting portion A2, and the portions B2 and B3 extending on both sides are the four wires, The other two wires 21c and 21d are in contact with each other from the inside. Further, the portions B2 and B3 extending on both sides abut the wires 21e and 21f radially extending from the crossed portion A1 located at the end of the region woven in a lattice shape from the inside, and extend outside the region. Have been.
[0049]
In the example shown in FIG. 3C, a portion B bent in a U-shape is formed by connecting portions B2 and B3 extending to both sides from the bent front end portion B1 with a cross located at an end of a region woven in a lattice shape. It is inserted from the outer peripheral side and entangled in the opposing lattice spaces C1 and C2 of the portion A1 that intersects in the shape. The tip B1 abuts from the outside on the two wires 21a and 21b of the four wires extending radially from the intersecting portion A1, and the portions B2 and B3 extending on both sides are of the above four wires. After abutting against the remaining two wires 21c and 21d from inside, respectively, the wires are extended out of the region woven in a lattice shape.
[0050]
8 to 11 are pattern diagrams each showing another example of the knitting structure employed in the stent of the present invention.
[0051]
In the example of FIG. 8, the regions D3 and D4 woven in a lattice shape extend in the circumferential direction in parallel with each other. A portion B bent in a U-shape extends from one region D4 to the other region D3. The bent portion B is entangled with the cross-shaped portion A formed in the region D <b> 3, with its distal end directed toward the outer peripheral side of the stent 20. Between the regions D3 and D4, a region D5 is formed in which both side portions of the portion B bent in a U-shape extend in parallel.
[0052]
In the example of FIG. 9, in the example of FIG. 8, a large number of U-shaped bent portions B extending from one region D4 toward the other region D3 are formed at a smaller pitch than the above. It is entangled with each of the cross-shaped portions A formed in D3. Therefore, in the region D3, many portions entangled with the portion A where the bent portion B intersects are arranged at a smaller pitch than in the example of FIG. Further, the arrangement pitch of the wires 21 in the region D5 is also narrowed.
[0053]
In the example of FIG. 10, in the example of FIG. 8, a portion B bent in a U-shape extends from the region D3 toward the region D4, and the portion B bent in the U-shape intersects. The portion entangled with the portion A is formed not only in the region D3 but also in the region D4. Therefore, the region D5 is a region in which the wires on both sides of the U-shaped bent portion B extending from both the regions D3 and D4 are arranged in parallel.
[0054]
In the example of FIG. 11, in the example of FIG. 10, a large number of U-shaped bent portions B extending from both the regions D3 and D4 are arranged at a narrower pitch. Therefore, a large number of portions, which are formed in the regions D3 and D4 and are entangled with the crossing portion A of the U-shaped bent portion B, are also formed at a narrower pitch.
[0055]
【The invention's effect】
As described above, according to the present invention, the diameter of the tubular organ can be easily reduced when the catheter is attached to the inner periphery of the catheter, and when the tubular organ is pushed out of the catheter, the tubular organ can be expanded with a sufficient expanding force. it can.
[0056]
In addition, when the stent is bent, the bent portion comes in contact with the cross-shaped crossing portion and a frictional force is applied, and it is easy to maintain the bent shape, so it is arranged at the bent portion of the tubular organ. Even in this case, the repulsive force is reduced due to the adaptation to the bent shape, and the application of a local pressing force to the inner wall of the tubular organ is reduced.
[0057]
Furthermore, when the stent is bent, the tip of the bent portion may protrude toward the outer periphery of the stent, but does not protrude toward the inner periphery, thereby affecting blood flow flowing inside the stent. There is no fear of giving.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a graft with a stent according to the present invention, wherein (a) is a perspective view of a stent used in the graft, and (b) is a perspective view of the stent-graft in which a cylindrical cover is partially cut away. .
FIG. 2 is a partially developed view showing a knitting pattern of the graft with a stent.
FIG. 3 is an explanatory view showing a state where the stent-attached graft is arranged inside an aneurysm of a blood vessel.
FIG. 4 is an explanatory diagram showing stress when the graft with a stent is bent.
FIG. 5 is an explanatory diagram showing, in an enlarged manner, a state outside and a state inside a portion where a wire is entangled when the graft with a stent is bent.
FIG. 6 shows, as a comparative example, an enlarged view of the outer and inner states of the wire-entangled portion when a stent in which the tips of the U-shaped bent portions are entangled is bent. FIG.
FIG. 7 is a partial pattern diagram showing different examples of entangled shapes in the knitted structure employed in the stent of the present invention.
FIG. 8 is a partial pattern diagram showing another example of the knitting structure used in the stent of the present invention.
FIG. 9 is a partial pattern diagram showing still another example of the knitting structure used in the stent of the present invention.
FIG. 10 is a partial pattern diagram showing still another example of the knitting structure used in the stent of the present invention.
FIG. 11 is a partial pattern diagram showing still another example of the knitting structure used in the stent of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Graft with stent 20 Stent 21 Metal wire 30 Cylindrical cover A The part which crosses in the cross B The part which bends in a U-shape B1 The tip part B2, B3 The part D1, D3, D4 which extends on both sides The area | region woven in the lattice form D2, D5 A region where both sides of the bent portion extend in parallel.

Claims (4)

In a stent formed by knitting a metal wire into a tubular shape, the metal wire has a crossed portion and a U-shaped bent portion in the knitted structure of the metal wire, and the U-shaped bent portion is provided. The bent portion is entangled with the portion crossing in a cross shape with its bent distal end toward the outer peripheral side. 2. The U-shaped bent portion is formed by inserting a portion extending from the bent tip portion to both sides into an opposing lattice space of the cross-shaped cross portion from an outer peripheral side and entangled. Stent. 3. The stent according to claim 1, wherein a portion where the crossed portion and the bent portion are entangled is arranged in a ring or spiral shape along a circumferential direction. 4. A stent-attached graft comprising the stent according to claim 1 and a cylindrical cover covering an inner periphery and / or an outer periphery of the stent.

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