JP2004174281A - Placement stent within the living body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a placement stent within the living body which is easy to place in the living body, in addition does not cause damage to tissues within the living body when placing, and moreover, can retain the widening of a living body hollow or a body cavity securely after placement. <P>SOLUTION: A stent 1 has a cylindrical frame 2, an opening 4 marked off by a frame 6a, 6b comprising the cylindrical frame 2, and a cutout part 5 marked off by the frame 6a. The frame 2 has both ends 3a, 3b. The stent 1 is formed by a superelastic metal and is a casting which does not have a convulsive change of solid state properties such as a junction. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a stent for indwelling in a living body used for improving a stenosis in a living body such as a blood vessel, a bile duct, a trachea, an esophagus, a urethra, and other organs.

  2. Description of the Related Art Conventionally, various stents have been proposed for inserting into a stenosis of a living body lumen or body cavity such as a blood vessel, a bile duct, an esophagus, a trachea, a urethra, and other organs to secure a lumen or body cavity space.

  Stents are divided into self-expandable stents and balloon-expandable stents according to function and placement method. The balloon expandable stent does not have a function of expanding the stent itself.To place the stent at the target site, insert the stent into the target site, then place the balloon inside the stent, expand the balloon, and expand the balloon. The stent is expanded (plastically deformed) by force, and is fixed in close contact with the inner surface of the target site. Therefore, in the case of this type of stent, the operation of expanding the stent as described above is required.

  In the self-expandable stent, the stent itself has contraction and expansion functions. In order to place the stent at the target site, the stent is inserted into the target site in a contracted state, and then the stress applied to maintain the contracted state is removed. For example, this is performed by shrinking and storing the stent in a tube having an outer diameter smaller than the inner diameter of the target portion, and after pushing the distal end of the tube to the target portion, extruding the stent from the tube. When the extruded stent is released from the tube, the stress load is released, and the stent is restored to the shape before contraction and expanded. Thereby, it adheres and fixes to the inner surface of the target part. This type of stent does not require an expansion work like a balloon expandable stent, and is easy to perform.

  Various types of such self-expandable stents have been proposed. Specifically, a stent using a superelastic metal is disclosed in Japanese Patent Publication No. 5-43392 (Patent Document 1). The catheter disclosed in Japanese Patent Publication No. 5-43392 (Patent Document 1) has a sheath covered around the outer periphery, and a living organ dilator (stent) is attached between the sheath and the insertion distal end side. As the vessel (stent), a strain in which the strain at the time when the action is exerted after the sheath is removed and the strain at the time when the sheath is attached to the sheath before the insertion is in the superelastic region is used. And, as the shape of the stent, a coil, a cylindrical, a roll, a deformed tubular, a higher coil, a leaf spring coil, a basket or a mesh are shown. ing.

Japanese Patent Publication No. 5-43392

The stent disclosed in Japanese Patent Publication No. 5-43392 (Patent Document 1) uses a superelastic metal exhibiting superelasticity before and after insertion into a living body, and is therefore placed in a living body. Since the operation is easy and the stent placed in the living body constantly exhibits superelasticity, the living body lumen or body cavity can be expanded for a long term. However, the stent disclosed in Japanese Patent Publication No. 5-43392 (Patent Document 1) has the shape as described above.
First, in a coil shape, a roll shape, a higher coil shape, and a leaf spring coil shape, when inserted into a living body, the stent expands, and at this time, ends, for example, both ends of the coil, side ends of the roll, Department moves. In other words, in order to return to the basic shape from the reduced diameter state, the length of the coil is reduced, and accordingly, the distance between the ends of the coil is also reduced. The length of the roll does not change, but the distance between the side edges changes. The stent is exposed in the living body in a state of being released from the sheath, and the movement of the end of the stent often occurs in a state of being in contact with the inner surface of the living body lumen or body cavity, thereby causing a risk of damaging the inner body surface. There is. Then, there is a higher possibility that the stenosis will be caused again than the damage given.

  Further, a simple cylindrical shape does not have the above-mentioned problems, but it is not easy to reduce the diameter, and it is difficult to insert it into a living body. In the case of a deformed tubular type, the rate of diameter reduction is small, and there is a risk that stenosis may occur again due to a portion protruding inward, further impeding blood flow and the like. A cage or a mesh-shaped stent is not easy to form using a superelastic metal wire, and may be displaced at the intersection of the metal wires. Making decisions difficult.

  An object of the present invention is to facilitate the indwelling operation in a living body by using a superelastic metal that exhibits superelasticity before and after insertion into a living body, and furthermore, damage the tissue in the living body during the indwelling. It is an object of the present invention to provide a stent for indwelling in a living body that can reliably maintain an expanded state of a living body lumen or body cavity after being placed without giving it.

What achieves the above object is formed of a superelastic metal exhibiting superelasticity in a substantially cylindrical shape before and after insertion into a living body, and further has a plurality of notches or a plurality of notches formed on a side surface. Has a deformation assisting function that assists deformation in the direction in which the outer diameter is reduced at the time of a stress load formed by the openings, and is integrally formed without forming sudden changes in physical properties as a whole. In-vivo indwelling stent. The notch or the opening is formed by partially cutting and removing the side surface of the superelastic metal pipe by laser with the indwelling stent, and furthermore, the stent has no edge in the whole. It is in a chamfered state, and a heat-denatured portion formed during the cutting or melting is removed.
In addition, what achieves the above-mentioned object has a notch or an opening formed by partially cutting and removing a side surface of a metal pipe by a laser, and a sharp change in physical properties is formed as a whole. This is an in-vivo indwelling stent that is integrally formed without being edged, and is an in-vivo indwelling stent that is chamfered without edges as a whole.
And the said stent connects the 1st frame body provided with the said notch part or opening, the 2nd frame body provided with the said notch part or opening, and the 1st frame body and the 2nd frame body. Preferably, a connection frame is provided.

  The opening is preferably circular or polygonal. The opening is preferably an ellipse or a polygon in which the axial direction of the stent is longer than the direction orthogonal to the axis of the stent. Preferably, the cutout is semicircular or polygonal.

  Further, the surface of the stent is preferably coated with a biocompatible metal or a biocompatible resin. The biocompatible metal is, for example, one of gold, silver, platinum, and titanium.

  Since the stent of the present invention has a substantially cylindrical shape, and the deformation assisting function is constituted by a plurality of cutouts or a plurality of openings formed on the side surfaces, the stent is expanded when the stent is expanded (in other words, when the stent is indwelled, stress is reduced). When the stent is unloaded (when the diameter is reduced) and when the stent is not placed (when the diameter is reduced), there is little difference in shape and size between the two, and the stent is deformed in the axial direction during shape restoration in vivo. The amount is small, and there is little damage to the inner wall of the living body at the time of shape restoration. Further, the length of the stent, which can be confirmed by the contrast image of the stent during the placement operation, hardly changes even during the placement, so that accurate placement at the target site is possible. Further, since no sudden change in physical properties is formed in the stent, there is no portion to which metal stress is continuously applied, and there is little risk of breakage even if the stent is left for a long time. Furthermore, when applied to a so-called vasodilator stent in which blood flows inside, an unnatural flow is not formed in the blood flow flowing inside, thereby preventing the stent from causing re-stenosis.

The stent of the present invention will be described with reference to an embodiment shown in the drawings.
FIG. 1 is a plan view of one embodiment of the stent of the present invention.
The stent 1 of the present invention is formed in a substantially cylindrical shape from a superelastic metal exhibiting superelasticity before and after insertion into a living body. And, it has a deformation assisting function of assisting the deformation in the direction in which the outer diameter is reduced when a stress is applied, which is constituted by a plurality of notches or a plurality of openings formed on the side surface of the cylindrical body 2. Further, the whole is integrally formed without abrupt changes in physical properties.

Specifically, the stent 1 has a shape as shown in FIG.
The stent 1 of this embodiment has a cylindrical frame body 2, an opening 4 partitioned (bent) by frames 6 a and 6 b constituting the cylindrical frame 2, and a notch 5 partitioned by the frame 6 a. The frame 2 has both ends 3a and 3b. The entire stent 1, in other words, the frame body 2, is formed of a superelastic metal, and is formed integrally so as not to form a sudden change in physical properties such as a connection portion.

  Each of the ends 3a and 3b is constituted by a set of a plurality of arcs on one circle, and they are separated from each other at substantially equal angles. In other words, the end of the frame body 2 is almost a perfect circle if the notch 5 is not formed, and by forming the notch 5, a plurality of arcs spaced equiangularly from the center of the frame 2 are formed. ing. The ends 3a and 3b are formed by end side surfaces of the frame 6a. The frame 6 a is formed so as to extend obliquely at a predetermined angle with respect to the center axis of the frame body 2. Two frames 6a continuous at the ends 3a and 3b form two equal sides of an isosceles triangle. The frames 6a at both ends are connected by a frame 6b. The frame 6b is formed substantially parallel to the central axis of the frame body 2. In this embodiment, the width of the frame 6b is almost twice the width of the frame 6a. The cross-sectional shape of each of the frames 6a and 6b when cut in a direction perpendicular to the center axis of the frame body is a fan shape in which the upper side is an arc, the bottom side is an arc shorter than the upper side, and the side is a straight line. Further, the outer surface of the frame (stent) is chamfered without edges as a whole. Thereby, the stent can be further prevented from damaging the inner wall of the living body,

  In this stent 1, since the notch is provided at the end of the frame body, the ends 3a and 3b of the stent can be easily deformed, and in particular, the ends can be partially deformed. Good response. Further, since the end 3 is formed by the ends of the plurality of frames 6a, the end 3 is hardly crushed and has sufficient strength. An opening 4 surrounded by frames 6a and 6b is formed between both ends, and this opening 4 is easily deformed by deformation of the frame 6a. For this reason, the stent 1 can be easily deformed at its central portion (the central portion of the frame body 2).

In this embodiment, the opening 4 has a crushed hexagonal shape, and the cutout portion 5 has an isosceles triangle. In addition, a plurality of cutouts 5 are formed at each end, specifically six cutouts 5, each having substantially the same shape. In addition, a plurality of openings 4 are formed, specifically, six openings 4 so as to form side surfaces of the stent 1. The shape and the number of the notches and the openings are not limited to the above-mentioned shapes and numbers, and the number of the notches is preferably 3 to 10 and the number of the openings is preferably about 3 to 10.
The stent 1 has an outer diameter of 2.0 to 30 mm, preferably 2.5 to 20 mm, and an inner diameter of 1.4 to 29 mm, preferably 1.6 to 29.4 mm, and has a length of: It is 10 to 150 mm, more preferably 15 to 100 mm.

  As the superelastic metal forming the stent 1, a superelastic alloy is preferably used. The superelastic alloy mentioned here is generally called a shape memory alloy, and exhibits superelasticity at least at a biological temperature (around 37 ° C.). Particularly preferably, a TiNi alloy of 49 to 53 atomic% Ni, a Cu-Zn alloy of 38.5 to 41.5 wt% Zn, and a Cu-Zn-X alloy of 1 to 10 wt% X (X = Be, Si, Superelastic metal bodies such as Sn, Al, Ga) and a 36-38 atomic% Al-Ni-Al alloy are preferably used. Particularly preferred is the above-mentioned TiNi alloy. In addition, a Ti-Ni-X alloy in which a part of the Ti-Ni alloy is substituted with 0.01 to 10.0% X (X = Co, Fe, Mn, Cr, V, Al, Nb, W, B, etc.) Or a Ti—Ni—X alloy (X = Cu, Pb, Zr) in which part of the Ti—Ni alloy is substituted with 0.01 to 30.0% of atoms, and a cold working rate Alternatively, by selecting the conditions of the final heat treatment, the mechanical properties can be appropriately changed.

The buckling strength (yield stress under load) of the superelastic alloy used is 5 to 20 kg / mm ² (22 ° C.), more preferably 8 to 150 kg / mm ² , and the restoring stress (unloading time). Yield stress) is 3 to 180 kg / mm ² (22 ° C.), more preferably 5 to 130 kg / mm ² . Superelasticity here means that even if the metal is deformed (bent, tensioned, compressed) to the area where normal metal plastically deforms at the operating temperature, it recovers to almost its original shape without the need for heating after the deformation is released. Means that.
The stent 1 is formed by removing (for example, cutting or dissolving) a notch and an opening portion using, for example, a superelastic metal pipe, so that a sharp change in physical properties is not formed. It is an integral product. If there is a sudden change in physical properties, that part will show a different deformation kinetics than the other parts. Further, there is a risk that metal stress is applied to a portion having different physical properties and the portion is damaged. In addition, if there is a change in the physical properties, the stent as a whole becomes unnaturally deformed, an unnatural flow is formed in the blood flow flowing inside, and again causes stenosis. However, the stent according to the present invention does not have the above-described problem because it is formed of an integrated product in which abrupt changes in physical properties are not formed.

The superelastic metal pipe used for forming the stent 1 is melted in an inert gas or vacuum atmosphere to form a superelastic alloy ingot such as a Ti-Ni alloy, and the ingot is mechanically polished. Then, a large diameter pipe is formed by hot pressing and extrusion, and then the die drawing step and the heat treatment step are sequentially repeated to reduce the diameter to a pipe having a predetermined thickness and an outer diameter. Alternatively, it can be manufactured by physical polishing.
The notch or the plurality of openings can be formed in the superelastic metal pipe by laser processing (for example, YAG laser), electric discharge processing, chemical etching, cutting processing, and the like. Is also good.
Next, the stent of the embodiment shown in FIG. 2 will be described.

The basic shape of the stent 10 of this embodiment is the same as that shown in FIG.
The stent 10 is used when a stenosis is formed over a relatively long portion or when a blood vessel having a stenosis is meandering or curved. The shape is a shape in which the two stents shown in FIG. 1 are connected by a frame 6c. The stent 10 is also formed of an integrally formed product in which no sudden change in physical properties is formed, similarly to the above-described product.

  Specifically, in the stent 10, the ends of the frame 6a facing each other are connected at only one position by the frame 6c (connection frame), and the ends of the other frames 6a are free ends. As described above, since the connection is made at only one location, the connection between the frame body 2a (first frame body) and the frame body 2b (second frame body) can be greatly deformed, and the constricted portion extends over a long portion. It is effective for improving blood vessels formed, meandering or curved blood vessels, and the like. And one blood vessel can be improved by one stent, and there is no need to deploy a plurality of stents.

  The shape of the stent is not limited to the stent shown in FIGS. 1 and 2. For example, like the stent 20 shown in FIG. 3, trapezoidal cutouts are formed at both ends and a honeycomb shape is formed at the center. A plurality of hexagonal openings are formed, and as in the stent 30 shown in FIG. 4, rectangular notches are formed at both ends, and a plurality of rectangular notches are formed at the center (double the notch). ) Having an opening (having a length of).

  In the stent of FIGS. 1 to 4 described above, when the stent is expanded (in other words, at the time of indwelling, at the time of stress unloading) and when the stent is not indwelled (reduced diameter state), the stent is not indwelled. Sometimes the notch and the opening extend slightly in the axial direction of the stent, and there is little difference in shape and size between the two. For this reason, the amount of deformation at the time of shape restoration in the living body is small, that is, there is almost no movement of the end of the stent in the living body at the time of shape restoration, and therefore, it is possible to damage the inner wall of the living body at the time of shape restoration. Few.

  In addition, the stent of the present invention may be formed of only a superelastic metal, but the outer or inner wall of the superelastic metal pipe 4 or both surfaces may be coated with a biocompatible material. As the biocompatible material, a synthetic resin or a metal having a biocompatible material can be considered. Examples of methods for coating the surface of the stent with an inert metal include gold plating using an electroplating method, stainless steel plating using a vapor deposition method, silicon carbide using a sputtering method, titanium nitride plating, and gold plating.

  The synthetic resin can be selected from thermoplastic or thermosetting resins. For example, polyolefin (eg, polyethylene, polypropylene, ethylene-propylene copolymer, etc.), polyvinyl chloride, and ethylene-vinyl acetate copolymer may be used. Copolymers, polyamide elastomers, polyurethanes, polyesters, fluororesins, silicone rubbers and the like can be used, and preferably, polyolefins, polyamide elastomers, polyesters or polyurethanes, and biodegradable resins (for example, polylactic acid, polyglycolic acid, Copolymer). It is preferable that the synthetic resin coating is flexible enough not to hinder the curvature of the frame constituting the stent. The thickness of the synthetic resin film is 5 to 300 μm, preferably 10 to 200 μm.

  As a method of thinly coating the surface of the stent with a synthetic resin, for example, a method of inserting a superelastic metal pipe into a synthetic resin in a molten state or a solution state to coat the same, or polymerizing a monomer on the surface of the superelastic metal pipe There is a chemical vapor deposition for coating while being performed. When an extremely thin resin coating is required, coating using a dilute solution or chemical vapor deposition is preferable.

  Further, in order to further improve the biocompatible material, the resin film may be coated or fixed with an antithrombotic material. As the antithrombotic material, various known resins can be used alone or as a mixture. For example, polyhydroxyethyl methacrylate, a copolymer of hydroxyethyl methacrylate and styrene (for example, HEMA-St-HEMA) Block copolymer) can be suitably used.

Next, a method for manufacturing the stent of the present invention will be described.
In the method for producing a stent of the present invention, a step of preparing a superelastic metal pipe having an outer diameter adapted to an in-vivo site to be indwelled, and partially removing a side surface of the prepared superelastic metal pipe, At least a step of forming a plurality of notches or a plurality of openings.

  The superelastic metal pipe is melted in an inert gas or vacuum atmosphere to form a superelastic alloy ingot, such as a Ti-Ni alloy, and mechanically polishing the ingot, followed by hot pressing and extrusion, A large diameter pipe is formed, and then the die drawing step and the heat treatment step are sequentially repeated to reduce the diameter to a pipe having a predetermined thickness and an outer diameter, and finally manufactured by chemically or physically polishing the surface. be able to.

  The step of forming the plurality of cutouts or the plurality of openings on the side surface can be performed by, for example, laser processing (for example, YAG laser), electric discharge machining, cutting by mechanical polishing, or chemical etching. Further, they may be performed in combination. And since the stent is formed by processing the pipe in this way, the outer diameter of the pipe becomes the outer diameter of the stent as it is, the dimensional accuracy after preparation is high, and it returns to the prepared shape when placed in the living body Therefore, the stenosis can be reliably improved. In addition, since the physical property change point is hardly formed, there is no breakage due to metal stress accumulated at the rapid change in physical property and unnatural blood flow formation.

  Specifically, in the step of forming a notch or an opening in the side surface of the superelastic metal pipe, first, the superelastic metal pipe is subjected to electric discharge machining to remove a portion to be the notch and the opening by heating and melting, and remove the stent. An electric discharge machining (primary machining) process for initial machining into a substantially target shape of the above is performed. Subsequently, a chamfering step (secondary processing) for shaving off the edge of the stent formed body subjected to the electric discharge processing is performed. The chamfering step is performed by, for example, blasting using hard fine particles. Deburring and chamfering are performed by this blast processing. Then, in order to remove the heat denatured portion formed on the periphery of the stent formed body during the electric discharge machining, a heat denatured portion processing step (tertiary processing, chemical etching) is performed. This heat denaturation partial treatment step is performed, for example, by immersing the blasted stent formed body in a denaturation part treatment liquid in which a small amount of hydrogen peroxide is mixed with a mixture of hydrofluoric acid and nitric acid. Note that deburring and chamfering may be performed simultaneously by chemical etching (thermally modified partial processing step), and in this case, the blast processing step may not be performed.

  The primary processing in the step of forming a notch or an opening in a side surface of the superelastic metal pipe is performed by laser processing a prepared superelastic metal pipe having a predetermined outer diameter with a laser device (for example, a YAG laser device). It can also be performed by doing. Also in this laser processing, similarly to the above-mentioned electric discharge machining, a portion to be a notch and an opening is removed by heating and melting by laser irradiation, and the superelastic metal pipe is processed into a substantially desired shape of the stent.

The step of forming a notch or an opening in the side surface of the superelastic metal pipe may be performed by using a photofabrication technique as described below.
In this method, the inner and outer surfaces of the superelastic metal pipe are first degreased and cleaned. Degreasing and washing are performed, for example, by immersion in a surfactant aqueous solution, immersion in RO water, or immersion in a cleaning organic solvent such as hexane. After drying, a photoresist is applied to the outer and inner surfaces of the superelastic metal pipe. The photoresist may be either a positive type or a negative type, and may be a UV resist, an electron beam resist, or an X-ray resist. The thickness of the photoresist is preferably about 0.5 to 4 μm. Then, a heat treatment (prebaking) is performed at about 80 to 90 ° C. in order to increase the adhesion of the photoresist film to the pipe.

  Subsequently, a masking film having a pattern corresponding to the shape of the notch or opening on the side surface of the superelastic metal pipe (the photoresist is different depending on the positive type or the negative type) was wound around the outer surface of the superelastic metal pipe and brought into vacuum contact. Thereafter, an exposure operation is performed. The exposure operation can be performed using, for example, an ultra-high pressure mercury lamp. In this case, it is preferable to perform the rotation while rotating the superelastic metal pipe so that the entire surface is irradiated with certainty. Then, a developing process is performed. The development process is performed by immersing the superelastic metal pipe in a photoresist developer. Then, it heats to 120-145 degreeC and performs a post-baking process. Thus, the masking step is completed.

In this manner, no photoresist is present in the notch or opening on the side surface of the superelastic metal pipe, and the hardened photoresist is present in the portion of the frame forming the notch or opening. A superelastic metal pipe is created. The stent formed body is immersed in an edging solution to dissolve and remove the notch or opening. The cutout or opening of the superelastic metal pipe is in contact with the edging liquid and thus is dissolved, and the frame is not dissolved by the hardened photoresist because it does not contact the edging liquid. By this edging liquid treatment, a stent formed body having a substantially external shape of the stent is created. Then, the cured photoresist adhering to the surface of the stent formed body is removed. This is done by immersing the stent in a solution that dissolves the hardened photoresist. Further, blasting is performed as described above for removing and chamfering burrs formed on the periphery of the stent. Furthermore, it is immersed in an edging solution to perform a surface treatment. Thereby, the stent of the present invention is produced.
Further, if necessary, a step of forming a metal plating or a resin film on the stent is performed.

Next, specific examples of the stent of the present invention will be described.
(Example 1)
A TiNi alloy (51 atomic% Ni) alloy pipe was cold-worked to produce a superelastic metal pipe having an outer diameter of 7.8 mm, an inner diameter of 7.0 mm, and a length of about 15 mm. Then, using an NC electric discharge machine (with an A3R rotary head) manufactured by Soldick Co., Ltd., a super-elastic metal pipe was set on the movable side, and a machining die was set on the fixed side to obtain a shape as shown in FIG. Was made. The electric discharge machining was performed at a machining current of 2 A and a servo voltage of 3 to 4 V. In this state, the width of the frame 6a shown in FIG. 1 was 0.45 mm. Then, in order to chamfer the edge of the frame of the stent, blasting was performed at a pressure of ^{2 to 3} kg / cm ² using glass beads having a particle size of 15 to 30 μm. Deburring and chamfering were performed by this blast processing, and as a result, the width of the frame 6a shown in FIG. 2 became 0.40 mm.

  Next, a heat denatured portion formed on the periphery of the frame during electric discharge machining was removed. In this work, a denatured treatment solution was prepared by mixing a small amount of hydrogen peroxide solution with a mixed solution of hydrofluoric acid and nitric acid, and the blast-treated stent was treated with this treatment solution (about 40 ° C.) for about 2 minutes. The immersion was performed by chemically etching the outer surface of the stent. The stent after this chemical etching has the shape as shown in FIG. 1, the average outer diameter is 7.6 mm, the average thickness is 0.29 mm, and the average width of the frame 6a is 0.35 mm. there were. Then, the formed stent was restored to the created shape even when deformed with a finger. Therefore, the heat-denatured portion (the portion not showing superelasticity) was almost removed. This stent can be used for stenosis improvement of the iliac artery, femoral artery, and bile duct.

(Example 2)
An alloy pipe made of a TiNi alloy (51 atomic% Ni) was cold-worked to prepare a superelastic metal pipe having an outer diameter of 4.2 mm, an inner diameter of 3.6 mm, and a length of about 15 mm. Then, laser processing was performed using a YAG laser device [ML-4140A, manufactured by Miyachi Technos Co., Ltd.]. The processing is repeated twice by inserting a stainless steel mandrel having an outer diameter of 3.6 mm and a length of 100 mm into the superelastic metal pipe and under laser irradiation conditions (current 16 A, irradiation speed 10 mm / min). As shown in FIG. 2, a stent formed body in which two stents were continuous was formed. The average wire diameter of this stent formed body was 0.35 mm. Then, in order to chamfer the edge of the frame of the stent formed body, blasting was performed at a pressure of ^{2 to 3} kg / cm ² using glass beads having a particle size of 15 to 30 μm. Deburring and chamfering were performed by this blasting, and as a result, the average frame diameter of the stent frame was 0.31 mm.

  Next, a heat-denatured portion formed on the periphery of the frame during laser processing was removed. In this work, a denatured treatment solution was prepared by mixing a small amount of hydrogen peroxide solution with a mixed solution of hydrofluoric acid and nitric acid, and the blast-treated stent was treated with this treatment solution (about 40 ° C.) for about 2 minutes. The immersion was performed by chemically etching the outer surface of the stent. The stent after this chemical etching had the shape as shown in FIG. 2, the average outer diameter was 4.06 mm, and the average wire diameter was 0.15 mm. Then, the formed stent was restored to the created shape even when deformed with a finger. Therefore, the heat-denatured portion (the portion not showing superelasticity) was almost removed. This stent is used for improving coronary stenosis.

(Example 3)
Using the stent of Example 2, the entire surface was gold-plated to increase its biocompatibility. Gold plating was performed by heating a sulfamic acid-based plating bath (Auroflex TI, manufactured by Tokuriki Honten Co., Ltd.) to about 40 ° C. to dissolve potassium cyanide, and immersing the stent of Example 2 in this plating bath. did. As a result, a 1.8-μm non-glossy gold plating layer was formed on the surface of the stent. This stent is also used for improving the stenosis of the coronary artery as in the second embodiment.

(Example 4)
An alloy pipe made of a TiNi alloy (51 atomic% Ni) was cold-worked to prepare a superelastic metal pipe having an outer diameter of 4.2 mm, an inner diameter of 3.6 mm, and a length of about 15 mm. This superelastic metal pipe was first immersed in a surfactant aqueous solution, subsequently, immersed in RO water, dried, immersed in hexane, degreased and washed.

  The superelastic metal pipe was immersed in a photoresist (a positive type photoresist, manufactured by Tokyo Ohka Kogyo Co., Ltd., trade name OFPR-800) solution to form a coating having a thickness of about 2 μm on the inner and outer surfaces. The superelastic metal pipe was heated at 85 ° C. for 30 minutes to perform prebaking. Then, a masking film in which a portion corresponding to a notch portion and an opening portion of the stent was cut out was prepared, wound around an outer surface of a superelastic metal pipe, and further adhered in vacuum. Subsequently, an exposure process was performed. The exposure treatment was performed for 15 seconds at an output of 3 mw and an exposure of 250 mJ / cm using an ultrahigh pressure mercury lamp while rotating the superelastic metal pipe at a speed of 300 rpm.

  Next, the treated superelastic metal pipe was immersed in a developer (trade name: NMP, manufactured by Tokyo Ohka Kogyo Co., Ltd.) to perform development processing. The developed superelastic metal pipe was post-baked at 130 ° C. for 30 minutes. Then, 20 ml of distilled water, 45 ml of glycerin, 25 ml of nitric acid (specific gravity 1.40), and 1 ml of hydrofluoric acid (40%) were mixed to prepare an edging solution. Then, the superelastic metal pipe was immersed in an edging solution heated to about 40 ° C. for about 20 minutes. Subsequently, the superelastic metal pipe was immersed in acetone to dissolve the photoresist. As a result, the notched portion and the portion that becomes the opening were removed from the superelastic metal pipe, and a stent formed body having a shape almost as intended as shown in FIG. 2 was obtained. The wire diameter b of the stent formed body was 0.32 mm.

A side edge peculiar to the wet edging method is formed on the stent formed body, and in order to remove the side edge, glass beads having a particle size of 15 to 30 μm are blasted at a pressure of ^{2 to 3} kg / cm ² . did. Deburring and chamfering were performed by this blast processing. In order to further improve the surface condition, a surface treatment solution prepared by mixing a small amount of hydrogen peroxide solution with a mixture solution of hydrofluoric acid and nitric acid is prepared, and a stent blasted as described above in this treatment solution (about 40 ° C.). The formation was immersed for about 2 minutes to chemically etch the surface of the stent. The stent after this chemical etching had the shape as shown in FIG. 2, and had an average outer diameter of 4.12 mm and an average wire diameter of 0.28 mm. Then, the formed stent was restored to the created shape even when deformed with a finger. Therefore, the heat-denatured portion (the portion not showing superelasticity) was almost removed. This stent is used for improving coronary stenosis.

FIG. 1 is a perspective view of one embodiment of the stent of the present invention. FIG. 2 is a perspective view of another embodiment of the stent of the present invention. FIG. 3 is a perspective view of another embodiment of the stent of the present invention. FIG. 4 is a perspective view of another embodiment of the stent of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Stent 2 Cylindrical frame body 2a, 2b Frame body 3a, 3b Both ends 6a, 6b, 6c Frame 4 Opening 5 Notch 10 Stent 30 Stent 40 Stent

Claims (8)

An in-vivo indwelling body that has a notch or opening formed by partially cutting and removing the side surface of a metal pipe with a laser, and that is integrally formed without forming sudden changes in physical properties as a whole A stent for indwelling in a living body, characterized in that the stent is chamfered without edges as a whole. A stress load formed by a superelastic metal exhibiting superelasticity in a substantially cylindrical shape before and after insertion into a living body, and formed by a plurality of cutouts or a plurality of openings formed on a side surface. An in-vivo indwelling stent that has a deformation assisting function that sometimes assists deformation in a direction in which the outer diameter is reduced, and is integrally formed without forming sudden changes in physical properties as a whole. In the indwelling stent, the notch or the opening is formed by partially cutting and removing the side surface of the superelastic metal pipe by using a laser. Characterized in that the stent is in a chamfered state and a thermally denatured portion formed during the cutting or melting is removed. The stent according to claim 1, wherein the opening is circular or polygonal. 3. The stent for indwelling in a living body according to claim 1, wherein the opening has an elliptical or polygonal shape in which the axial direction of the stent is longer than a direction perpendicular to the axis of the stent. The stent for indwelling in a living body according to claim 1 or 2, wherein the notch has a semicircular shape or a polygonal shape. The stent for indwelling in a living body according to any one of claims 1 to 5, wherein a biocompatible metal or a biocompatible resin is coated on a surface of the stent. The in-vivo stent according to claim 6, wherein the biocompatible metal is, for example, one of gold, silver, platinum, and titanium. The stent includes a first frame body provided with the notch or opening, a second frame body provided with the notch or opening, and a connection frame connecting the first frame body and the second frame body. The stent for indwelling in a living body according to any one of claims 1 to 7, comprising:

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