JP2021052967A - Stent - Google Patents

Abstract

To provide a stent that can control a coating part coating an outside surface of an interweaving type stent from being detached due to wear.SOLUTION: A stent 1 is formed by interweaving a wire material 10 including: a skeleton wire 20 including a proximal end and a distal end and a coil wire 40; and a coating part 30 for coating an outside surface of the skeleton wire 20, where the coil wire helically turns around the skeleton wire 20 from a proximal end side to a distal end side of the skeleton wire 20.SELECTED DRAWING: Figure 4

Description

The present invention relates to a stent.

A stent is a medical device used to dilate a stenosis or occlusion site and secure a lumen in order to treat various diseases caused by stenosis or occlusion of a lumen such as a blood vessel or a gastrointestinal tract. .. Stents consist of a mesh structure and are obtained by braiding wires or laser cutting tubes.

Regarding the stent placement site, for example, in the case of a lower limb artery, the stent may be deformed and fractured due to expansion / contraction, twisting, compression, etc. of a blood vessel due to postoperative movement. Therefore, when a stent is placed in a blood vessel having a large amount of deformation, it is preferable to use a stent made of a material having good resilience to deformation and having good durability. A superelastic alloy such as NiTi is known as a material having good resilience to deformation. Further, regarding durability, it is known that a stent formed by braiding a wire (hereinafter, referred to as a braided stent) has better durability than a stent formed by another manufacturing method.

On the other hand, in recent years, a drug-eluting stent (DES: Drug) that coats the outer surface of a stent with a drug capable of suppressing the migration and proliferation of vascular smooth muscle cells and elutes the drug at the stent placement site to prevent restenosis. Eluting Stent) is being developed.

In this regard, for example, in Patent Document 1 below, the outer surface of the braided stent is coated with a polymer in order to limit the elution amount of the drug, and the drug is contained in the polymer. With such stents, the polymer acts as a barrier and slows the diffusion rate of the drug. That is, the period until the drug disappears becomes longer, and the period during which the drug has a medicinal effect becomes longer.

Japanese Unexamined Patent Publication No. 2004-237118

However, the braided stent according to Patent Document 1 does not have a structure or a component for improving the retention of the polymer. In a braided stent, the wires are likely to rub against each other during delivery storage, release, and indwelling, so the coating containing the polymer or drug covering the outer surface of the stent may peel off prematurely. is there.

The present invention has been made to solve the above-mentioned problems associated with the prior art, and an object of the present invention is to provide a stent capable of suppressing the coating portion covering the outer surface of the braided stent from being peeled off by friction. And.

The stent according to one aspect of the present invention is formed by knitting a composite wire having a first wire and a second wire having a proximal end portion and a distal end portion and a coating portion covering the outer surface of the first wire. The second wire is spirally swirled around the first wire from the base end side to the tip end side of the first wire.

According to the above-mentioned stent, the second wire can suppress the peeling of the coating portion covering the outer surface of the first wire.

It is the schematic which shows the structure of the stent which concerns on this embodiment. It is a partially enlarged view which shows the structure of the wire rod forming a stent. It is a partial cross-sectional view which shows the structure of a wire rod. It is a partially enlarged view which shows the structure of a wire rod. It is a partially enlarged view which shows the modification of the structure of a wire rod. It is a partially enlarged view which shows the modification of the structure of a wire rod. It is a partially enlarged view which shows the modification of the structure of a wire rod. It is a partially enlarged view which shows the modification of the structure of a wire rod. It is a schematic diagram which shows the manufacturing method of a wire rod. It is a schematic diagram which shows the manufacturing method of a wire rod. It is a schematic diagram which shows the manufacturing method of a wire rod. It is a schematic diagram which shows the manufacturing method of a wire rod. It is a schematic diagram which shows the manufacturing method of a wire rod. It is a schematic diagram which shows the manufacturing method of a stent. It is a schematic diagram which shows the manufacturing method of a stent. It is a schematic diagram which shows the manufacturing method of a stent. It is a schematic diagram which shows the joining method of the end part of a wire rod. It is a schematic diagram which shows the joining method of the end part of a wire rod. It is a schematic diagram which shows the joining method of the end part of a wire rod. It is a schematic diagram which shows the joining method of the end part of a wire rod. It is a schematic diagram which shows the joining method of the end part of a wire rod.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a schematic view showing the configuration of the stent 1 according to the present embodiment, FIG. 2 is a partially enlarged view showing the configuration of the wire rod 10 forming the stent 1, and FIG. 3 is a partially enlarged view showing the configuration of the wire rod 10. It is a partial cross-sectional view shown, and FIG. 4 is a partially enlarged view which shows the structure of the wire rod 10.

(Stent substrate, shape)
As shown in FIG. 1, the stent 1 is a long tubular body. The stent 1 is formed of a plurality of wires (corresponding to "composite wires") 10 and is formed by knitting the plurality of wires 10 in a mesh shape.

As shown in FIGS. 2 to 4, the wire rod 10 includes a skeleton wire (corresponding to the “first wire”) 20, a coating portion 30 for coating the skeleton wire 20, and a coil wire (corresponding to the “second wire”). ) 40 and.

In the present specification, in each component of the stent 1 and the stent 1, the portion including a certain range in the axial direction from the proximal end (the most proximal end) is defined as the "base end portion", and the portion from the tip end (state-of-the-art) to the axis The part including a certain range in the direction is defined as the "tip part".

(Skeletal wire)
The skeleton wire 20 is a wire that serves as a skeleton of the stent 1. The size of the skeletal wire 20 is not particularly limited as long as it can exert a force to spread the narrowed portion. For example, the diameter of the skeleton wire 20 according to the present embodiment is 60 to 500 μm, preferably 80 to 250 μm, and more preferably 100 to 150 μm.

The material of the skeleton wire 20 is preferably an alloy or polymer having superelastic properties or biodegradability. As an alloy having superelastic properties, for example, Ni—Ti alloy is known, and as an alloy having biodegradability, for example, Mg alloy is known. Further, it is more preferable to have both superelastic properties and biodegradability, and as such an alloy, an Mg—Sc alloy as described in International Publication No. 2017/065208 is known.

When the skeletal wire 20 has superelastic properties, the stent 1 placed in the narrowed portion of the blood vessel can be deformed according to movements such as expansion and contraction, twisting, and compression of the blood vessel. Since the blood vessels of the lower limbs are greatly deformed, the skeleton wire 20 needs to be made of a material having high durability against repeated deformation and restoration. Therefore, the skeleton wire 20 is preferably made of a superelastic alloy.

When the skeletal wire 20 is biodegradable, the stent 1 placed in the narrowed portion of the blood vessel can be decomposed and disappear after the narrowed portion of the blood vessel is improved.

The blood vessel in which the stent 1 is placed can maintain a patency state after a certain period of time. Therefore, the blood vessel does not need to be supported by the stent 1. If the stent 1 is not made of a biodegradable material, the stent 1 will remain in the vessel for an extended period of time after the vessel has improved, but the stent 1 may break in the vessel due to aging. In this case, the fractured stent 1 may damage the intravascular tissue and cause restenosis. In addition, the presence of a stent 1 that is harder than the vascular tissue may limit the motor function of the blood vessels and promote arteriosclerosis.

In addition, when a stent 1 is placed in the gastrointestinal tract to improve benign gastrointestinal stenosis, if the stent 1 is placed in the gastrointestinal tract for a long period of time, it may cause perforation or fall off from the place where the stent 1 is placed. there's a possibility that. In addition, when the stenosis is improved, the stent 1 may be removed, but the digestive tract may be damaged. Therefore, the skeletal wire 20 forming the stent 1 is preferably made of a biodegradable material that is decomposed and disappears after the narrowed portion is improved.

The material of the skeleton wire 20 is not particularly limited as long as it has either superelastic properties or biodegradability. Specific examples of alloys having superelastic properties other than Mg-Sc alloys include Ni-Ti alloys (which may include Co, Fe, Zr, Hf, Pd, Au, Fe, Pt, and Mo) and Cu alloys. (Al, Mn, Ni, Zn may be contained), Mg alloy (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, Nd, and other rare earth metals may be contained. ). Specific examples of alloys having biodegradability other than Mg-Sc alloys include Mg alloys (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, Nd). , Other rare earth metals may be included)), Zn alloy (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, and other rare earth metals may be included), Fe alloy ( Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, and other rare earth metals may be included).

(Coating part)
As shown in FIG. 4, the coating portion 30 includes a polymer coat 30A and a drug coat 30B arranged on the upper part (outside) of the polymer coat 30A. The coating portion 30 covers the outer surface of the skeleton wire 20.

The polymer coat 30A can suppress the progress of corrosion of the skeleton wire 20. Therefore, the polymer coat 30A can retain the shape of the stent 1 placed in the narrowed portion of the blood vessel until the narrowed portion is improved.

The thickness of the polymer coat 30A is not particularly limited as long as the corrosion resistance can be controlled. For example, the thickness of the polymer coat 30A according to the present embodiment is 1 to 100 μm, preferably 2 to 30 μm, and more preferably 5 to 20 μm.

Specific examples of the polymer coat 30A include homopolymers composed of monomers such as L-lactic acid, D-lactic acid, DL-lactic acid, caprolactone, butyrolactone, valerolactone, glycolic acid, trimethylene carbonate, and paradioxanone. Examples include copolymers and copolymers or blended polymers thereof. Further, as a coating similar to a polymer, a diamond-like carbon coating (DLC), a fluorinated coating, a magnesium hydroxide coating and the like can be mentioned. These may be used alone or in combination of two or more.

The drug coat 30B can prevent restenosis due to excessive formation of the new endometrium in the blood vessel after the stent 1 is placed in the stenosis. The drug coat 30B has an immunosuppressive effect or a cell growth inhibitory effect, and can suppress the narrowing of the lumen of the stent 1 due to the excessively formed neointima.

The thickness of the drug coat 30B is not particularly limited as long as it can secure a drug capable of suppressing the restenosis described above. For example, the thickness of the drug coat 30B according to the present embodiment is 1 to 100 μm, preferably 2 to 40 μm, and more preferably 5 to 30 μm.

Specific examples of the drug coat 30B include sirolimus, everolimus, biolimus A9, zotarolimus, tacrolimus, cilostazol, paclitaxel. These may be used alone or in combination of two or more.

The coating portion 30 may include either the polymer coating 30A or the chemical coating 30B (see FIGS. 5B and 5C). Further, the polymer coat 30A may be composed of a plurality of polymer coat layers in order to control the corrosion resistance. Further, a top coat or the like for controlling the sustained release of the drug may be formed on the upper layer of the drug coat 30B, and the drug coat 30B may be composed of a plurality of coat layers for controlling the sustained release.

(Coil wire)
As shown in FIGS. 3, 4, 5A to 5D, the coil wire 40 is a wire that spirally swirls around the skeleton wire 20 from the base end side to the tip end side of the skeleton wire 20. .. As shown in FIGS. 5A to 5D, when the uppermost portion (outermost) of the outer surface of the coating portion 30 is arranged outside the coil wire 40, other wires (skeleton wire 20 or coil wire 40) or the coating portion Even if the coating portion 30 receives a force acting in the peeling direction due to friction from the 30 or the like, the starting point of the peeling remains on the outer surface of the coil wire 40. Therefore, the coil wire 40 can prevent the coating portion 30 from peeling off from the outer surface of the skeleton wire 20. In particular, as shown in FIGS. 3 and 4, when at least a part of the coil wire 40 is arranged outside the outermost surface of the outer surface of the coating portion 30, other wires (skeleton wire 20 or coil wire 40) or The friction from the coating portion 30 and the like acts directly on the coil wire 40 and does not act directly on the coating portion 30. Therefore, the coil wire 40 can further suppress the coating portion 30 from peeling off from the outer surface of the skeleton wire 20, and can improve the coating retention property.

When the stent 1 is placed at the target position of the lumen in the body, for example, the stent 1 is housed inside a tubular catheter (not shown), and the catheter is introduced from outside the body into the body at the target position. The procedure is performed in which the stent is delivered together with the catheter, only the catheter is removed from the stent 1, and the stent 1 is placed at a target position. In such a procedure, friction acts between the stent 1 and the catheter when the stent 1 is retracted and when the catheter is removed. Similarly, in such a case, the coil wire 40 of the present embodiment is the skeleton wire 20. It is possible to prevent the coating portion 30 from peeling off from the outer surface.

The size of the coil wire 40 is not particularly limited as long as it can be wound around the skeleton wire 20. For example, the diameter of the coil wire 40 according to the present embodiment is 10 to 200 μm, preferably 20 to 80 μm, and more preferably 30 to 70 μm.

The swivel interval of the coil wire 40 is such that in the region where the plurality of skeleton wires 20 forming the stent 1 overlap, the other skeleton wire 20 is swiveled at the swivel interval of the coil wire 40 swirling one skeleton wire 20. By preventing the coil wire 40 from entering, the distance is not particularly limited as long as the peeling of the coating portion 30 can be suppressed. For example, the turning interval of the coil wire 40 according to the present embodiment is 1 to 150 μm, preferably 2 to 100 μm, and more preferably 5 to 50 μm. The turning interval is the distance between the adjacent coil wires 40 and the side surfaces of the wires closest to each other.

The material of the coil wire 40 is preferably an alloy having elasto-plasticity or shape memory, and when a biodegradable alloy is used for the skeleton wire 20, it is preferably a biodegradable alloy. The biodegradable alloy having elasto-plasticity is, for example, Mg or an alloy containing Mg as a main component.

When the coil wire 40 is made of Mg alloy and the skeleton wire 20 is made of Mg—Sc alloy, galvanic corrosion can be suppressed. Galvanic corrosion is likely to occur when the coil wire 40 is made of an alloy having a large potential difference with the skeleton wire 20. Therefore, in the stent 1 of the present embodiment, galvanic corrosion can be suppressed by forming the coil wire 40 and the skeleton wire 20 with an Mg alloy. This allows the stent 1 to suppress unexpected premature degradation due to galvanic corrosion. When a biodegradable alloy is not used for the skeleton wire 20, for example, even when a Ni—Ti alloy is used for the skeleton wire 20, the potential difference between the skeleton wire 20 and the coil wire 40 becomes large, resulting in galvanic corrosion. May cause harmful ions to elute. Therefore, when the skeleton wire 20 is made of Ni—Ti alloy, galvanic corrosion can be suppressed by using Ni—Ti alloy having shape memory characteristics for the coil wire 40.

The coil wire 40 can be formed of the same Mg—Sc alloy as the skeleton wire 20 in order to suppress galvanic corrosion. However, the Mg—Sc alloy having superelastic properties is not preferable as a material for the coil wire 40.

The Mg—Sc alloy having superelastic properties has the property of returning to its original shape even when deformed as described above. Therefore, when the coil wire 40 is formed of Mg—Sc alloy, the clearance between the coil wire 40 and the skeleton wire 20 may be increased due to this characteristic. Therefore, the coil wire 40 formed of the Mg—Sc alloy may be difficult to prevent the coating portion 30 covering the outer surface of the skeleton wire 20 from peeling off. Therefore, the coil wire 40 is preferably formed of a heat-treated Mg—Sc alloy that does not have superelastic properties, or an Mg alloy that does not have superelastic properties.

When the coil wire 40 has elasto-plasticity, the clearance between the coil wire 40 and the skeleton wire 20 when manufacturing the wire rod 10 can be reduced. When the coil wire 40 has shape memory, the coil wire 40 can be wound around the skeleton wire 20 while being shaped into a desired shape when the wire rod 10 is manufactured. Therefore, when the coil wire 40 has elasto-plasticity or shape memory, it is possible to manufacture the wire rod 10 in which the clearance between the coil wire 40 and the skeleton wire 20 is controlled. Therefore, according to the stent 1 formed of the wire rod 10, it is possible to prevent the coil wire 40 from peeling off the coating portion 30 covering the outer surface of the skeleton wire 20.

Further, when the coil wire 40 is biodegradable, as described above, the stent 1 placed in the narrowed portion of the blood vessel can be decomposed and disappear after the narrowed portion of the blood vessel is improved.

The material of the coil wire 40 is not particularly limited as long as it has either elasto-plasticity, shape memory property, or biodegradability. Specific examples of alloys having elasto-plastic or shape memory other than Mg or alloys containing Mg as the main component include Ni—Ti alloys (Co, Fe, Zr, Hf, Pd, Au, Fe, Pt, Mo may be included), Co—Cr alloy, stainless steel and the like. Further, specific examples of Mg or alloys having biodegradability other than alloys containing Mg as a main component include Zn alloys (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc. , Cu, Ag, and other rare earth metals), Fe alloys (which may contain Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, and other rare earth metals) Can be mentioned.

Further, the arrangement relationship between the coil wire 40 and the coating portion 30 described above is not particularly limited as long as the coil wire 40 can prevent the coating portion 30 from peeling off from the outer surface of the skeleton wire 20. In the wire rod 10 according to the present embodiment, the arrangement of each component can be changed by appropriately changing the manufacturing process of the wire rod 10 described below.

Further, the clearance between the coil wire 40 and the skeleton wire 20 described above is not particularly limited as long as the coil wire 40 can improve the coating retention of the coating portion 30 and the coating portion 30 can be suppressed from being peeled off by friction. The coil wire 40 and the skeleton wire 20 may be in contact with each other or may be separated from each other.

(Manufacturing method of wire rod)
Next, a method for manufacturing the wire rod 10 in the present embodiment will be described. 6A to 6E are schematic views showing a method of manufacturing the wire rod 10.

The method for producing the wire rod 10 according to the present embodiment is roughly described by forming a polymer coat 30A on the outer surface of the skeleton wire 20 (S10) and forming a drug coat 30B on the upper part (outside) of the polymer coat 30A. (S20) and winding the coil wire 40 around the skeleton wire 20 coated by the coating portion 30 (S30). Hereinafter, a specific description will be given.

First, a polymer coat 30A and, if necessary, a first solution 30a in which other components are dissolved in a solvent are prepared. Then, as shown in FIG. 6A, the first solution 30a is applied or sprayed (hereinafter, referred to as coating) on the outer surface of the skeleton wire 20 by the nozzle N. Then, the solvent is removed from the first solution 30a by drying the first solution 30a coated on the outer surface of the skeleton wire 20. As a result, the polymer coat 30A is formed on the outer surface of the skeleton wire 20 as shown in FIG. 6B (S10).

Next, a second solution (not shown) in which the material of the drug coat 30B and, if necessary, other components are dissolved in a solvent is prepared. Then, the second solution is coated on the upper part (outer side) of the polymer coat 30A fixed on the outer surface of the skeleton wire 20. Then, the solvent is removed from the second solution by drying the second solution coated on the upper part of the polymer coat 30A. As a result, the drug coat 30B is formed on top of the polymer coat 30A as shown in FIG. 6C (S20).

The solvent in steps S10 and S20 is not particularly limited as long as the polymer can be dissolved, and for example, acetone, ethanol, methanol, dichloromethane, chloroform, carbon tetrachloride, and tetrahydrofuran (THF) can be used.

Further, the coating in steps S10 and S20 can be performed by using, for example, air spray, ultrasonic spray, dipping, CVD, PVD. In this case, the first solution 30a and the second solution (not shown) can be coated while rotating the skeleton wire 20, and the coating portions 30 can be formed on the entire circumference (both sides) of the skeleton wire 20.

However, the coating in steps S10 and S20 is not limited to the entire circumference of the skeleton wire 20, and may be applied only to a half circumference (one side) of the outer surface of the skeleton wire 20. In this case, air spray or ultrasonic spray is used for coating, and the coating is performed in a state where the skeleton wire 20 is fixed. According to this method, the coating portion 30 can be formed only on a half circumference (one side) of the outer surface of the skeleton wire 20.

The method for drying the first solution 30a and the second solution (not shown) is not particularly limited, and is appropriately performed by a method such as depressurization, ventilation, or heating.

Further, before coating in steps S10 and S20, the surface of the skeleton wire 20 is cleaned or surface-treated in order to improve the adhesion between the skeleton wire 20 and the first solution 30a and the second solution (not shown). May be performed as needed. Examples of the surface treatment method include chemical treatment with an oxidizing agent, fluorine gas, etc., surface graft polymerization, plasma discharge treatment, corona discharge treatment, UV / ozone treatment, electron beam irradiation, and the like.

Next, as shown in FIG. 6D, the coil wire 40 is wound around the skeleton wire 20 covered by the coating portion 30 (S30). At this time, as shown in FIG. 6E, the skeleton wire 20 is rotatably fixed to the fixed jig M with tension applied to both ends so as to be linear. Further, one end of the coil wire 40 (left side in the drawing) is fixed by sandwiching it with the skeleton wire 20 in the fixing jig M, and the other end of the coil wire 40 (right side in the drawing) is fixed via the roller R. It is gripped under tension. Then, the coil wire 40 is wound around the rotating skeleton wire 20 while being subjected to a constant load. The tension applied to the other end of the coil wire 40 can be set within a range in which the coil wire 40 can be wound by the rotation of the skeleton wire 20 and a range in which the coil wire 40 is not broken.

The method of fixing one end of the coil wire 40 to the skeleton wire 20 is not particularly limited. For example, methods such as welding, adhesive, and crimping may be used.

Further, step S30 may be performed mechanically or manually.

The wire rod 10 is manufactured by carrying out the above method, and the stent 1 is formed by knitting a plurality of wire rods 10 by the method for manufacturing the stent 1 described below.

The order of steps S10, S20, and S30 in the method for manufacturing the wire rod 10 can be changed. For example, when the steps are carried out in the order of steps S10, S30, and S20, the wire rod 10 as shown in FIG. 5A can be manufactured. Further, when the steps are carried out in the order of steps S30, S10 and S20, the wire rod 10 as shown in FIG. 5D can be manufactured. When steps S10 and S20 are performed after step S30, in addition to the steps described above, the first solution 30a and the second solution (not shown) sprayed on the outer surface of the coil wire 40 depend on the turning interval of the coil wire 40. You may perform the step of dropping it into the gap. Further, after the step S30, the stent 1 described later may be manufactured, and then the steps S10 and S20 may be carried out. Even in that case, it is possible to manufacture the stent 1 having the wire rod 10 as shown in FIG. 5D.

(Stent manufacturing method)
Next, the method for manufacturing the stent 1 in the present embodiment will be described. 7 to 9 are schematic views showing a method for manufacturing the stent 1.

The stent 1 is manufactured by winding a plurality of wire rods 10 around a mandrel 200 and knitting them. As a method for manufacturing the stent 1 according to the present embodiment, an example in which six wire rods 10 are woven at the same time will be described.

The winding start positions 10A to 10F of the six wires (not shown) are arranged at different positions in the axial direction or the circumferential direction of the mandrel 200. For example, as shown in FIG. 8, the winding start positions 10A to 10F are alternately arranged at one end 200A or the other end 200B of the mandrel 200, and are arranged at equal intervals of 60 ° in the circumferential direction of the mandrel 200. There is. The winding start position of the wire rod 10 can be appropriately changed depending on the number of wire rods 10 used for manufacturing the stent 1. In this way, by winding the plurality of wire rods 10 from different positions in the axial direction or the circumferential direction of the mandrel 200, the plurality of wire rods 10 can form a mesh-like elongated body.

Hereinafter, as a method of winding the wire rod 10 around the mandrel 200, the wire rod 10 is attached to the winding start position 10A of the winding start positions 10A, 10C, and 10E provided on the one end 200A side of the mandrel 200 with reference to FIG. A method of winding the wire rod 10 around the mandrel 200 will be described.

First, the wire rod 10 is spirally wound from the winding start position 10A to the folding pin P1 provided on the other end 200B side (see the thick wire in FIG. 7). Then, the wire rod 10 is folded back while being curved along the folding pin P1, and is spirally wound up to the winding start position 10A provided at one end 200A (see the thin wire in FIG. 7). Finally, both ends of the wire rod 10 are joined (corresponding to "fixing") at the winding start position 10A.

According to the method described above, when the wire rod 10 attached to the winding start positions 10B, 10D, and 10F provided on the other end 200B side of the mandrel 200 is wound around the mandrel 200, the folding pin (not shown) is a mandrel. One end of the 200 is provided on the 200A side. The wire rod 10 attached to the winding start positions 10B, 10D, and 10F is wound around the mandrel 200 in the same procedure as the winding start positions 10A, 10C, and 10E using a folding pin (not shown).

The method of winding the wire rod 10 around the mandrel 200 can be variously changed. For example, the winding start positions 10A to 10F may be provided at the central portion 200C (see FIG. 9) of the mandrel 200, and may be arranged at different positions in the axial direction of the mandrel 200.

For example, as shown in FIG. 9, the wire rod 10 attached to the winding start position 10A provided in the central portion 200C of the mandrel 200 is located on the other end 200B side from the winding start position 10A provided on the back surface of the mandrel 200. It is wound in a spiral shape up to the provided folding pin P2 (see the thick line in FIG. 9). Then, the wire rod 10 is folded back from the folding pin P2 and wound in a spiral shape from the folding pin P3 provided at one end 200A side (see the thin wire in FIG. 9). Then, the wire rod 10 is folded back from the folded pin P3 and wound in a spiral shape up to the winding start position 10A provided in the central portion 200C (see the alternate long and short dash line in FIG. 9). Finally, both ends of the wire rod 10 are joined at the winding start position 10A.

Further, the position of the folding pin corresponding to each of the winding start positions is not particularly limited.

(How to join the ends of the wire)
Next, a method of joining the ends of the wire rod 10 in the present embodiment will be described. 10 to 13B are schematic views showing a method of joining the end portions 10P and 10Q of the wire rod 10.

As described above, one end 10P and the other end 10Q of the wire rod 10 need to be joined when the stent 1 is manufactured.

The method of joining the one end portion 10P and the other end portion 10Q is a method of welding the base end surface of the one end portion 10P and the tip end surface of the other end portion 10Q (see FIG. 10), and the side surface of the one end portion 10P and the other end portion 10Q. Examples thereof include a method of welding the side surfaces (see FIG. 11). At this time, a joint portion 900 is formed at the contact portion between the one end portion 10P and the other end portion 10Q.

The coil wire 40 may not be wound around the skeleton wire 20 within a certain range from the base end surface of the one end portion 10P on which the joint portion 900 is formed and the tip end surface of the other end portion 10Q. The joining portion 900 joins at least the base end side end portion of the skeleton wire 20 of the one end portion 10P and at least the distal end side end portion of the skeleton wire 20 of the other end portion 10Q.

In particular, when the side surface of the one end portion 10P and the side surface of the other end portion 10Q are joined by welding (see FIG. 11), the coil wire 40 is wound around the skeleton wire 20 in order to further secure the bondability of the joining portion 900. It is preferable that this is not done.

Further, as a method of joining the one end portion 10P and the other end portion 10Q, a method using a tube 300 can be mentioned. As shown in FIG. 12, the tube 300 has an end portion 300A having a first opening 300a into which one end portion 10P of the wire rod 10 (the end portion on the base end side of the skeleton wire 20) can be inserted, and the other end portion of the wire rod 10. It has a second opening 300b into which 10Q (end end of the skeleton wire 20) can be inserted, and an other end 300B. At this time, one end 10P (the end on the base end side of the skeleton wire 20) and the other end 10Q (the end on the tip end side of the skeleton wire 20) are fixed inside the tube 300. The wire rod 10 and the tube 300 are connected by welding, and a joint portion 900 is formed inside the tube 300.

The material of the caulking tube 300 is not particularly limited. For example, the caulking tube 300 may be formed of a metal having a contrast medium in order to give the stent 1 a contrast medium, or an alloy containing a metal having a contrast medium as a main component. Specific examples of the contrast-enhancing metal include iridium, tantalum, gold, platinum, tungsten, and silver. In addition, superelastic Mg-Sc, elasto-plastic Mg alloy (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, Nd, and other rare earth metals may be contained. ), Ni—Ti alloy (may include Co, Fe, Zr, Hf, Pd, Au, Fe, Pt, Mo). Further, it may be formed of an alloy containing a metal having contrast as a main component.

Further, one end 10P (the end on the base end side of the skeleton wire 20) is inserted from the second opening 300b, and the other end 10Q (the end on the tip end side of the skeleton wire 20) is inserted from the first opening 300a. You may.

As described above, the method of joining the one end 10P and the other end 10Q of the wire rod 10 has been described, but the above method can be variously changed.

For example, the wire rod 10 may be joined by inserting the one end portion 10P and the other end portion 10Q into the caulking tube 400 and caulking them. The caulking tube 400 preferably has superelastic properties or elasto-plastic properties.

When the caulking tube 400 has elasto-plasticity, it is plastically deformed (caulked) in the compression direction from the outside to the inside. At this time, the wire rod 10 and the caulking tube 400 are firmly connected by returning to their original positions even if the skeleton wire 20 is deformed because it has superelastic properties.

The coil wire 40 may or may not be wound around the skeleton wire 20 of the wire rod 10 inserted into the caulking tube 400. Since the coil wire 40 is plastically deformed when the crimping tube 400 is plastically deformed from the outside to the inside in the compression direction, the connection between the crimping tube 400 and the wire rod 10 is not hindered.

Further, one end 10P and the other end 10Q can be joined by caulking with a caulking tube 400 and then welded. In this case, the wire rod 10 and the caulking tube 400 are more firmly connected. Laser welding and resistance welding can be used as the welding method.

When laser welding is used, the wire rod 10 and the caulking tube 400 are connected by applying heat from above the caulking tube 400 into which the wire rod 10 is inserted. Therefore, there is a possibility that a heat-affected portion (not shown) may be generated on the outer surface of the caulking tube 400. Since the affected portion changes the material structure of the caulking tube 400 by heat, there is a concern that the mechanical properties of the caulking tube 400 may be deteriorated (brittleness or the like) or the corrosion resistance may be deteriorated when laser welding is used.

When resistance welding is used, as shown in FIG. 13A, a joint portion 900 is formed between the inner surface of the caulking tube 400 and the outer surface of the skeleton wire 20, so that the outer surface of the caulking tube 400 is not affected by welding. Or less. Therefore, when resistance welding is used, it is possible to suppress deterioration of the mechanical properties of the joints between the ends of the wire rods 10 by the caulking tube 400, rapid corrosion, and breakage of the stent 1 due to corrosion. ..

The material of the caulking tube 400 is not particularly limited. For example, from the viewpoint of suppressing galvanic corrosion, the caulking tube 400 is preferably formed of an alloy having a composition similar to that of the skeleton wire 20. When a superelastic Mg-Sc alloy is used for the skeleton wire 20, the crimping tube 400 is made of an Mg alloy (Li, Al, Zn, Ca, Y, W, Zr, Gd, Mn, Sc, Cu, Ag, Nd, By using other rare earth metals), it is possible to suppress galvanic corrosion between the skeleton wire 20 and the caulking tube 400 as compared with the case where an alloy other than Mg alloy is used for the caulking tube 400. It is possible to suppress early decomposition. When a Ni—Ti alloy is used for the skeleton wire 20, the caulking tube 400 may contain a Ni—Ti alloy (which may contain Co, Fe, Zr, Hf, Pd, Au, Fe, Pt, Mo) or Ti. It is preferable to use an alloy or the like.

Further, the caulking tube 400 may be formed of a metal having a contrast medium in order to give the stent 1 a contrast medium, or an alloy containing a metal having a contrast medium as a main component. Specific examples of the contrast-enhancing metal include iridium, tantalum, gold, platinum, tungsten, and silver. Further, it may be formed of an alloy containing a metal having contrast as a main component.

Further, instead of imparting contrast to the caulking tube 400, a metal piece having contrast between one end 10P and the other end 10Q inserted into the caulking tube 400 (hereinafter, referred to as contrast metal) is used. It may be arranged (see FIG. 13B).

If galvanic corrosion is expected due to the fact that any of the skeleton wire 20, the coil wire 40, the metal caulking tube 400, and the contrast metal 500 forming the wire rod 10 are made of different alloys, the caulking tube 400 is used. It is preferable to dispose the contrast metal 500 coated with the polymer L between the inserted one end 10P and the other end 10Q (see FIG. 13B). This allows the stent 1 to suppress unexpected premature degradation due to galvanic corrosion.

As described above, the stent 1 according to the present embodiment has a skeleton wire (first wire) 20 and a coil wire (second wire) 40 having a proximal end and a tip, and a coating that covers the outer surface of the skeleton wire 20. The coil wire 40 is a stent formed by knitting the portion 30 and the wire rod 10 to be held, and the coil wire 40 spirally swirls around the skeleton wire 20 from the base end side to the tip end side of the skeleton wire 20. ..

With this configuration, the coil wire 40 can be wound around the skeleton wire 20 to prevent the coating portion 30 covering the outer surface of the skeleton wire 20 from peeling off.

Further, at least a part of the coil wire 40 is arranged outside the outer surface of the coating portion 30. As a result, the coil wire 40 can further suppress peeling of the coating portion 30 covering the outer surface of the skeleton wire 20, and can improve the coating retention property.

Further, the skeleton wire 20 is formed of a superelastic material, and the coil wire 40 is formed of an elasto-plastic material or a shape memory material. Since the skeletal wire 20 has superelastic properties, the stent 1 placed in the narrowed portion of the blood vessel can be deformed according to the movement of the blood vessel. Further, since the coil wire 40 has elasto-plasticity or shape memory, the clearance between the coil wire 40 and the skeleton wire 20 or the coating portion 30 can be controlled when the wire rod 10 is manufactured.

Further, the skeleton wire 20 and the coil wire 40 are preferably formed of a biodegradable material. As a result, the stent 1 placed in the narrowed portion of the blood vessel can be decomposed and disappear after the narrowed portion of the blood vessel is improved.

Further, the skeleton wire 20 is formed of an Mg—Sc alloy, and the coil wire 40 is formed of Mg or an alloy containing Mg as a main component. As a result, in the stent 1, galvanic corrosion can be suppressed by forming the coil wire 40 and the skeleton wire 20 with the same Mg alloy. Therefore, the stent 1 can suppress unexpected early degradation due to galvanic corrosion.

Further, the coating portion 30 includes a polymer coat 30A having an effect of suppressing the progress of corrosion of the skeleton wire 20. As a result, the polymer coat 30A can retain the shape of the stent 1 placed in the narrowed portion of the blood vessel until the narrowed portion is improved.

Further, the coating portion 30 includes a drug coat 30B having an immunosuppressive effect or a cell growth inhibitory effect. Thereby, the drug coat 30B can suppress the restenosis caused by the excessive formation of the new endometrium in the blood vessel after the stent 1 is placed in the stenosis portion.

The diameter of the skeleton wire 20 is 60 to 500 μm, and the diameter of the coil wire 40 is 10 to 200 μm. As a result, the coil wire 40 can be wound around the skeleton wire 20.

The turning interval of the coil wire 40 is 1 to 150 μm. As a result, in the region where the plurality of skeleton wires 20 forming the stent 1 overlap, the coil wires 40 swirling the other skeleton wire 20 are arranged at the swirling interval of the coil wires 40 swirling the one skeleton wire 20. By preventing it from entering, peeling of the coating portion 30 can be suppressed. Therefore, the coil wire 40 can further suppress the peeling of the coating portion 30 covering the outer surface of the skeleton wire 20.

Further, the stent 1 has an end portion 300A having a first opening 300a into which the proximal end side end of the skeleton wire 20 can be inserted, and a second opening 300b into which the distal end side end portion of the skeleton wire 20 can be inserted. It further has a tube 300 having an other end 300B. The base end side end portion and the tip end side end portion of the skeleton wire 20 are fixed in the tube 300. Thereby, the base end side end portion of the skeleton wire 20 of the wire rod 10 forming the stent 1 and the distal end side end portion of the skeleton wire 20 can be joined.

Although the medical device according to the present invention has been described above through the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of claims.

1 stent,
10 Wire (composite wire),
20 Skeleton wire (first wire),
30 coating part,
30A polymer coat,
30B drug coat,
40 coil wire (second wire),
200 mandrel,
300 tubes,
400 caulking tube,
500 contrast metal.

Claims (10)

A stent formed by knitting a composite wire having a first wire and a second wire having a base end portion and a tip end portion and a coating portion covering the outer surface of the first wire.
The second wire is a stent that spirally swirls around the first wire from the base end side to the tip end side of the first wire. The stent according to claim 1, wherein at least a part of the second wire is arranged outside the outer surface of the coating portion. The first wire is made of a superelastic material.
The stent according to claim 1 or 2, wherein the second wire is made of an elasto-plastic material or a shape memory material. The stent according to any one of claims 1 to 3, wherein the first wire and the second wire are formed of a biodegradable material. The first wire is made of Mg—Sc alloy and
The stent according to claim 3 or 4, wherein the second wire is formed of Mg or an alloy containing Mg as a main component. The stent according to any one of claims 1 to 5, wherein the coating portion includes a polymer coat having an effect of suppressing the progress of corrosion of the first wire. The stent according to any one of claims 1 to 6, wherein the coating portion comprises a drug coat having an immunosuppressive effect or a cell growth inhibitory effect. The diameter of the first wire is 60 to 500 μm.
The stent according to any one of claims 1 to 7, wherein the diameter of the second wire is 10 to 200 μm. The stent according to any one of claims 1 to 8, wherein the swivel interval of the second wire is 1 to 150 μm. It has one end having a first opening into which the base end side end of the first wire can be inserted, and the other end having a second opening into which the tip end side end of the first wire can be inserted. Has more tubes,
The stent according to any one of claims 1 to 9, wherein the proximal end side end portion and the distal end side end portion of the first wire are fixed in the tube.

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