JP2009034127A - Coated stent and method for producing the same - Google Patents

Abstract

Provided is a coated stent having a coating film, which has high flexibility and excellent followability to a body lumen.
A covered stent 10 of the present invention is formed of a strut 21 and has a cylindrical stent base material 20 having a gap portion 22 formed between the struts 21 and at least an outer periphery of the strut 21 of the stent base material 20. The coating film 30 is provided so as to cover a part and fill the gap portion 22, and the film thickness of the coating film 30 in the gap portion 22 is 1 μm to 40 μm.
[Selection] Figure 2

Description

  The present invention relates to a coated stent that secures the patency of a body lumen by being placed in a body lumen such as a bile duct, and a manufacturing method thereof. The present invention relates to a coated stent having excellent followability to the above and a manufacturing method thereof.

  When the digestive tract such as bile duct, urinary tract, respiratory tract, genital tract, etc. are narrowed or occluded by cancer cells, etc. In order to ensure survival, it is known to place a stent in a site where a body lumen is narrowed or occluded.

  A stent generally has a cylindrical outer shape, and is inserted into a body lumen in a contracted state so that the outer diameter of the cylinder is reduced. It is a medical device that is expanded and placed so that its diameter increases. Stents are broadly classified into self-expandable stents and balloon-expandable stents depending on the form of expansion. The stents are usually made of a metallic material so that they can be expanded. It has a cylindrical shape with a gap.

  However, if a stent formed of a metal material is placed in a blood vessel as it is, a thrombus formation is caused on the metal surface, resulting in a problem that the blood vessel is narrowed by the thrombus. Therefore, Patent Document 1 proposes a stent in which a stent body is covered with a polymer film containing a drug having antithrombotic properties such as heparin.

  In addition, when a stent having a void in the side wall is used when the stent is placed in a body lumen such as a bile duct that is narrowed or occluded by cancer cells, the cancer cell grows to the inside of the stent through the void. In some cases, there was a problem that the lumen of the body eventually narrowed. Therefore, it is known that a film component formed of a plastic material is used for a stent placed in a body lumen that is narrowed or occluded by cancer cells such as bile ducts in order to fill a void (space) of the stent component. (See, for example, Patent Document 2).

  Since the stent described in Patent Document 1 is formed by manufacturing a cylindrical polymer film and bringing it into close contact with the outer periphery of the stent body, on the inner peripheral surface side of the stent, However, the unevenness of the metallic stent body still exists. If the inner peripheral surface of the stent placed in the blood vessel has irregularities, the irregularities cause disturbances in the blood flow inside the stent, resulting in a problem that blood clots are likely to occur.

 In the stent described in Patent Document 2, since the stent film component is provided so as to cover the stent component even on the inner peripheral surface side of the stent, there is no unevenness of the stent component itself. However, since the film thickness of the stent film component is almost the same between the portion where the stent component is present and the portion where the stent component is not present, there are irregularities in the stent component itself on the outer peripheral surface side and the inner peripheral surface side of the stent. Corresponding irregularities of the stent film components are present. When a stent placed in a digestive tract such as a bile duct has irregularities on its inner peripheral surface, there is a problem that wastes such as bile mud accumulate on the irregularities and cause infection.

 Therefore, Patent Document 3 proposes to cover not only the outer peripheral surface of the stent body but also the inner peripheral surface thereof with a polymer layer, and further smooth the inner peripheral surface of the stent with the polymer layer. When this stent is used, since the inner peripheral surface of the stent formed by the polymer layer is smooth, the above-described problems caused by the irregularities on the inner peripheral surface of the stent do not occur.

  However, the stent described in Patent Document 3 has a drawback that it lacks the flexibility necessary for the stent body. If the stent is not flexible enough, the stent will not be able to follow the curved body lumen, and the stent will be displaced from its intended indwelling position, or the stent will be loaded into the body lumen and will re-apply. There is a possibility that a problem of causing stenosis may occur.

JP 11-299901 A JP-A-8-47540 JP 2004-261567 A

  In view of the above circumstances, an object of the present invention is to provide a coated stent having high flexibility and excellent followability to a body lumen while being a coated stent having a coating film.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the thickness of the coating film in the gap portion has a great influence on the flexibility of the covered stent. That is, in the stent described in Patent Document 3, it has been clarified that the polymer layer in the portion where the stent strut does not exist is too thick, and the inherent flexibility of the stent body is lost. And the present inventors can obtain a coated stent having high flexibility by setting the film thickness of the coating film in the void portion to a specific range, and in forming the coating film on the stent substrate, It has been found that if a specific method is employed, such a covered stent can be manufactured relatively easily, and the present invention has been completed.

  Thus, according to the present invention, a cylindrical stent base material formed by struts and having a gap portion formed between the struts, and covering at least a part of the outer periphery of the strut of the stent base material, and the gap portion. The coated stent is provided with a coating film provided to fill the gap, and the thickness of the coating film in the gap portion is 1 μm to 40 μm.

  In the coated stent, the thickness of the coating film on the strut surface on the outer peripheral surface side of the stent base material is 10% to 100% with respect to the thickness of the coating film in the void portion of the stent base material. Is preferred.

  In the coated stent, the thickness of the coating film on the strut surface on the outer peripheral surface side of the stent base material is preferably 1 μm to 20 μm.

  In the coated stent, the thickness of the coating film on the strut surface on the inner peripheral surface side of the stent base material is preferably 0 to 20 μm.

  In the coated stent, the strut surface coating film on the inner peripheral surface side of the stent base material and the coating film on the void portion of the stent base material, or the strut surface on the inner peripheral surface side of the stent base material and It is preferable that the inner peripheral surface of the stent base material formed by the coating film on the void portion of the stent base material is formed substantially smoothly.

  In addition, according to the present invention, the coating film is formed on the stent base material by rotating the shaft with the stent base material fitted on the shaft member, and attaching the resin solution to the stent base material rotating on the shaft. A method of manufacturing the coated stent is provided.

  ADVANTAGE OF THE INVENTION According to this invention, although it is a covered stent which has a coating film, it has high softness | flexibility and is excellent in the followability with respect to a body lumen, and the coating | cover which can obtain such a covered stent comparatively easily A method for manufacturing a stent is provided.

  Hereinafter, the covered stent of the present invention will be described based on embodiments shown in the drawings. FIG. 1 is an overall view showing an embodiment according to the coated stent of the present invention. FIG. 2 is an enlarged cross-sectional view of the coated stent shown in FIG.

  A coated stent 10 shown in FIGS. 1 and 2 is a cylindrical stent substrate 20 formed of struts 21 and a coating film that is provided so as to cover the stent substrate 20 and covers at least a part of the outer periphery of the struts 21. 30.

  The stent base material 20 is formed in a cylindrical shape by arranging struts 21 in a mesh shape. For this reason, the outer peripheral surface side of the stent base material 20 is comprised by the strut 21 and the space | gap part 22 formed between the struts 21. As shown in FIG.

  Various designs of the shape of the strut 21 in the stent base material 20 are known, but the stent base material 20 used for obtaining the covered stent 10 of the present invention has the strut 21 and the void portion 22. As long as it is, the design of the shape of the strut 21 is not limited, and a conventionally used one can be used.

  The length and outer diameter of the stent base material 20 are not particularly limited, and may be determined according to the site where the covered stent 10 is placed, but the length is usually 10 mm to 200 mm, and the outer diameter is 3 mm to 30 mm.

  The width (width in the horizontal direction with respect to the cylinder surface) and thickness (width in the direction perpendicular to the cylinder surface) of the struts 21 constituting the stent base material 20 are not particularly limited, but the width is usually 1 mm to 20 mm. Yes, the thickness is 0.1 mm to 3 mm. Further, the cross-sectional shape of the strut 21 is not particularly limited, and can be, for example, a square, a rectangle, a trapezoid, or a circle.

  Although the space | interval of the adjacent struts 21 in the stent base material 20, ie, the width | variety of the space | gap formed between the struts 21, is not specifically limited, Usually, they are 0.1 mm-30 mm.

  As the material constituting the struts 21, a metal or a resin is usually used. However, in order to obtain the covered stent 10 of the present invention, a metal is preferably used. As the metal to be used, for example, a superelastic alloy such as a nickel titanium alloy, stainless steel, tantalum, titanium, cobalt chrome alloy or the like can be used, but it is preferable to use a superelastic alloy, and in particular, a nickel titanium alloy is used. preferable.

  The method for obtaining the stent substrate 20 is not particularly limited, and a conventionally known method can be used. For example, by cutting the pipe by a technique such as laser processing (for example, YAG laser), electric discharge processing, chemical etching, There is a method of making the wall surface of the pipe mesh.

  The stent base material 20 may be provided with an X-ray marker formed of an X-ray contrast material (X-ray opaque material) so that the position can be confirmed by X-ray fluoroscopy when placed in the body lumen. Thereby, the position of the stent base material 20 can be grasped under X-ray contrast. As the radiopaque material, for example, an X-ray contrasting metal such as gold, platinum, platinum iridium alloy, platinum, silver, stainless steel, or an alloy thereof is suitable. Further, the X-ray marker may be a resin molded product containing an X-ray contrast material powder. As the X-ray contrast material powder, barium sulfate, bismuth subcarbonate, tungsten powder, the above-described metal powder, and the like can be used.

  As shown in FIG. 2, the coated stent 10 is provided with a coating film 30 so as to cover the strut 21 of the stent base material 20 and fill the gap portion 22. As a material constituting the coating film 30, a resin is usually used, but among them, a material that dissolves in an organic solvent and has low toxicity is preferable.

  Examples of the resin that can be used for the coating film 30 include conjugated diene polymers such as polybutadiene, polyisoprene, styrene-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer; polyε-caprolactone; polyurethane; cellulose acetate; Cellulosic polymers such as celluloid, cellulose nitrate, acetyl cellulose and cellophane; polyamide polymers such as polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 12 and polyamide 46; polytetrafluoroethylene, polytrifluoroethylene, Fluoropolymers such as perfluoroethylene-propylene copolymer; polystyrene, styrene-ethylene-propylene copolymer, styrene-ethylene-butylene copolymer, styrene-i Prene copolymer, chlorinated polyethylene-acrylonitrile-styrene copolymer, methacrylate ester-styrene copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, acrylate ester-acrylonitrile-styrene copolymer Styrenic polymers such as polymers; polyethylene, chlorinated polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, polypropylene, olefin -Olefin polymers such as vinyl alcohol copolymer and polymethylpentene; Formaldehyde polymers such as phenol resin, amino resin, urea resin, melamine resin, and benzoguanamine resin; Polybutylene terephthalate, polyethylene terephthalate Polyester polymers such as acrylate and polyethylene naphthalate; epoxy resins; (meth) acrylic polymers such as poly (meth) acrylic acid esters, poly-2-hydroxyethyl acrylate, methacrylic acid ester-vinyl acetate copolymers; Norbornene-based resins; silicone resins; polymers of hydroxycarboxylic acids such as polylactic acid, polyhydroxybutyric acid, and polyglycolic acid; These can be used alone or in combination of two or more.

  As the resin that can be used for the coating film 30, either a non-biodegradable resin or a biodegradable resin can be used, but it is preferable to use a non-biodegradable resin that is not easily decomposed in vivo. Among the functional resins, it is particularly preferable to use polyurethane. Moreover, you may mix | blend additives, such as chemical | medical agents, such as an anticancer agent and an antithrombotic agent, and anti-aging agent, with resin which comprises the coating film 30 as needed.

  In the coated stent 10 of the present invention, the thickness of the coating film 30 (a shown in FIG. 2) of the void portion 22 of the stent base material 20 needs to be 1 μm to 40 μm, and should be 1 μm to 30 μm. Preferably, it is 1 μm to 20 μm. If the coating film 30 in the gap portion 22 is too thin, the strength of the coating film 30 in that portion may be insufficient, or the effect of the drug may not be sufficiently exhibited when the coating film 30 contains the drug. . If the coating film 30 in the gap portion 22 is too thick, the coated stent 10 is not flexible enough to follow the curved body lumen, and the stent may deviate from the intended placement position. There is a risk that the stent will cause restenosis due to the load on the body lumen.

  In the covered stent 10, the coating film 30 needs to cover the strut 21, but does not necessarily need to cover the entire strut 21. The outer peripheral surface 21A side of the strut 21 is preferably covered with the coating film 30, but the inner peripheral surface 21B side of the strut 21 may be covered with the coating film 30 or may be exposed.

  In the covered stent 10, the thickness of the coating film 30 (b shown in FIG. 2) of the strut 21 on the outer peripheral surface 21A side of the stent base material 20 is preferably 1 μm to 20 μm, and more preferably 1 μm to 15 μm. It is preferably 1 μm to 10 μm, particularly preferably. Further, the thickness of the coating film 30 of the strut 21 on the inner peripheral surface 21B side of the stent base material 20 (c shown in FIG. 2) is preferably 0 to 20 μm, more preferably 1 μm to 15 μm, It is especially preferable that it is 1 micrometer-10 micrometers.

  The film thickness of the coating film 30 on the outer peripheral surface 21A side of the strut 21 is preferably 10% to 100%, more preferably 30% to 100%, with respect to the film thickness of the coating film 30 in the gap portion 22. More preferably, it is particularly preferably 50% to 100%. By making the coating film 30 in such a form, the coating film 30 on the outer peripheral surface 21A side of the strut 21 is too thick while the coating film 30 on the outer peripheral surface 21A side of the strut 21 is sufficiently thick. It is prevented from becoming too thick.

  The covered stent 10 preferably has a substantially smooth inner peripheral surface 30A. That is, when the inner peripheral surface 21B side of the strut 21 is covered with the coating film 30, it is preferable that the coating film on the inner peripheral surface 21B side of the strut 21 and the coating film of the gap portion 22 are formed smoothly. When the inner peripheral surface 21B side of 21 is not covered with the coating film 30, the inner peripheral surface 30A formed by the struts of the stent base material 20 and the coating film of the gap portion 22 is formed substantially smoothly. It is preferable. Thus, by forming the inner peripheral surface 30A of the covered stent 10 substantially smoothly, when placed in a blood vessel, a thrombus is unlikely to occur on the inner peripheral surface 30A of the covered stent 10, and the digestive tract When it is left in place, it becomes difficult for waste to accumulate on the inner peripheral surface 30A of the covered stent, and infectious diseases are prevented.

  The use of the coated stent 10 of the present invention is not particularly limited, and is used to ensure the patency of digestive organs such as bile ducts, body lumens such as blood vessels such as urinary tract, respiratory tract, and genital tract. Can do. Among these, the coated stent 10 of the present invention is preferably used for securing the lumen of the bile duct, which has many bends and branches and tends to be insufficient in flexibility with conventional coated stents.

  The method for obtaining the covered stent 10 of the present invention is not particularly limited, but according to the method for producing a covered stent of the present invention described below, the target covered stent 10 can be obtained relatively easily.

  FIG. 3 is a schematic view showing an embodiment according to the method for producing a covered stent of the present invention. In the method for producing a coated stent of the present invention, the shaft member 40 on which the stent base material 20 is fitted is axially rotated, and the resin solution is attached to the stent base material 20 that is axially rotated, whereby the coating film is formed on the stent base material 20. 30 is formed.

  First, the stent base material 20 is fitted on the shaft member 40. The shaft member 40 to be used is preferably a round bar, and the length thereof is preferably longer than that of the stent base material 20. The material of the shaft member 40 is not particularly limited, but a material having a smooth surface is preferably used, and glass is particularly preferably used.

  In the method for manufacturing a covered stent of the present invention, the inner diameter of the strut 21 of the covered stent 10 is selected by selecting the outer diameter of the shaft member 40 and adjusting the clearance between the stent base material 20 to be fitted and the shaft member 40. It is possible to adjust the film thickness of the coating film on the peripheral surface 21B side. For example, when a shaft member having an outer diameter slightly larger than the inner diameter of the stent base material 20 is used as the shaft member and the stent base material 20 is expanded and externally fitted, the stent base material 20 is contracted by the contraction force of the stent base material 20. Since there is almost no clearance between the shaft 20 and the shaft member 40, the thickness of the coating film on the stent inner peripheral surface 21B side is very thin, about 1 μm to 20 μm. It is also possible to prevent the coating film 30 from being present on the inner peripheral surface 21B side of the strut 21 by using the shaft member 40 having a larger outer diameter.

  The shaft member 40 on which the stent base material 20 is fitted is attached to a device such as a motor 41 for rotating the shaft. Although the direction of the shaft member 40 at the time of attachment is not specifically limited, It is preferable to attach in the horizontal direction.

  Next, the shaft member 40 fitted with the stent base material 20 is rotated. The rotation speed is not particularly limited, but is usually set to 50 to 300 rotations / minute.

  Next, the resin solution is attached to the stent base material 20 that rotates along with the shaft member 40. The resin solution is obtained by dissolving a resin for forming the coating film 30 in a solvent. The solvent to be used is usually an organic solvent that can dissolve the target resin, and preferably has high volatility. For example, when the coating film 30 is made of polyurethane, it is preferable to use tetrohydrofuran or a mixed solvent of tetrohydrofuran and 1,4-dioxane as the solvent.

  As for the film thickness of the coating film in the gap portion 22, the thickness of the gap portion 22 can be reduced by moving the resin solution staying in the portion in the outer peripheral direction by the centrifugal force generated by the shaft rotation of the shaft member 40. In controlling the thickness, adjustment of the concentration of the resin solution, the dripping amount of the resin solution, the rotation speed of the shaft member, and the like can be considered.

  A method of attaching the resin solution to the axially rotating stent base material 20 is not particularly limited, but it is preferable to drop the resin solution toward the stent base material 20 using a dropper 42 or the like. The dropping rate at this time is preferably 0.5 ml / min to 5 ml / min. The amount of the solution to be dropped can be specified based on the volume calculated from the surface area obtained from the stent dimensions.

  When the adhesion of the resin solution to the stent substrate 20 is completed, the solvent of the adhered resin solution is vaporized. When a highly volatile solvent is used, the solvent can be vaporized by continuing the axial rotation of the stent substrate 20 at room temperature.

  When the solvent is vaporized, the stent base material 20 is extracted from the shaft member 40. However, in many cases, when the stent base material 20 is simply extracted, the formed coating film 30 is damaged. In such a case, the stent base material 20 that is externally fitted to the shaft member 40 is immersed in a solvent such as ethanol by immersing the shaft base member 20 together with a solvent such as ethanol, and then the stent base material 20 is swelled from the shaft member 40. If 20 is extracted, the coating film 30 will not be damaged. When the coating film 30 is swollen, the stent base material 20 is extracted from the shaft member 40 and then the coating film 30 is dried.

  According to the method for manufacturing a covered stent of the present invention as described above, it is possible to easily adjust the film thickness of the coating film 30 in the gap portion 22 as compared with a conventionally known method. Thus, the covered stent 10 of the present invention can be obtained easily.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

〔Example〕
It has a trapezoidal cross-sectional shape in which a short side with a length of 0.18 mm is positioned on the outer peripheral surface side of the stent base material, and a long side with a length of 0.20 mm is positioned on the inner peripheral surface side of the stent base material. The struts made of nickel-titanium alloy having a diameter of 0.15 mm are arranged at intervals of a maximum of 2.5 mm, and are configured as shown in FIG. 1. The outer diameter is 10.0 mm and the length is 70 mm. A stent substrate was prepared.

  Next, by slightly expanding the diameter of the stent base material inside the obtained stent base material, a glass rod (round bar) having an outer diameter of 10.3 mm is inserted through the entire length of the stent base material. A stent base material was fitted on the outer peripheral surface.

One end of the glass rod on which the stent base material was fitted was fixed to a motor so that the glass rod was oriented in the horizontal direction, and the glass rod was axially rotated at a speed of 140 rotations / minute. Then, a tetrahydrofuran solution of a polyurethane resin (trade name: Estene) was dropped with a dropper onto the stent base material rotating with the glass rod. 1.5 ml of the solution was dropped onto the stent substrate while preventing the amount of the solution dropped from causing unevenness in the longitudinal direction of the stent substrate. Even after the dropping of the solution was completed, the glass rod was kept rotating at room temperature until the solvent on the stent substrate was vaporized. When the solvent on the stent substrate was vaporized, the glass rod was removed from the motor, and the stent substrate fitted on the glass rod was immersed in ethanol. By this operation, the polyurethane resin film formed on the stent substrate was swollen, and then the glass rod was pulled up from ethanol, and the stent substrate was removed from the glass tube. The removed stent substrate was allowed to stand at room temperature to dry the polyurethane resin film.
As described above, a coated stent of an example having a film made of polyurethane resin as a coating film was obtained. When the inner peripheral surface of the coated stent of this example was observed with the naked eye, no step was confirmed and the surface was smooth.

[Comparative Example 1]
After one end of a glass rod (round bar) having an outer diameter of 10.3 mm is immersed vertically in a tetrahydrofuran solution of polyurethane resin (trade name: Estene) in a container, the glass rod is solution at a rate of 1 cm / min. The solution was attached to the glass rod by pulling up from the glass rod. By leaving the glass rod at room temperature, the solvent on the glass rod was vaporized, and a polyurethane resin film was formed on the outer peripheral surface of the glass rod.

Next, a stent base material similar to that used in Example 1 is slightly expanded in diameter, and a glass rod and a polyurethane resin film formed on the outer peripheral surface thereof are inserted through the entire length of the stent base material. The stent base material was fitted onto the polyurethane resin film.
For the glass rod fitted with the stent base material, repeat the operation to form a polyurethane resin film in the same manner as before the stent base material was fitted, and form a polyurethane resin film on the outer peripheral surface of the stent base material. did. After the solvent is vaporized, the stent base material fitted on the glass rod is immersed in ethanol, and this operation swells the polyurethane resin film, and then the glass rod is pulled up from the ethanol, and the stent base material is made of the glass tube. Removed from. The removed stent substrate was allowed to stand at room temperature to dry the polyurethane resin film.
As described above, a coated stent of Comparative Example 1 having a film made of polyurethane resin as a coating film was obtained. When the inner peripheral surface of the coated stent of Comparative Example 1 was observed with the naked eye, no step was confirmed and the surface was smooth.

[Comparative Example 2]
It is made of polyurethane resin in the same manner as in Comparative Example 1 except that the operation of forming a polyurethane resin film on the outer peripheral surface of the glass rod was not performed before the stent base material was fitted onto the outer peripheral surface of the glass rod. A coated stent of Comparative Example 2 having the membrane as a coating membrane was obtained. When the inner peripheral surface of the coated stent of Comparative Example 2 was observed with the naked eye, no step was confirmed and the surface was smooth.

[Measurement of coating film thickness]
The coating film thickness of the coated stent was determined by cooling the coated stent, that is, the strut of the stent base material and the coating film in liquid nitrogen, and then cutting the section with a scissor. ) And observed.
The film thickness of the coating film in the gap portion 22 is measured at the center of the width of the gap formed between adjacent struts, and the film thickness of the coating film in the strut portion is measured on the outer peripheral surface side and the inner peripheral surface side. Each was measured at the center of the strut width. In addition, the measurement is performed at any three points on one covered stent for each of the gap portion 22, the outer peripheral surface side of the strut 21, and the inner peripheral surface side of the strut 21, and the average value is the coating film at that portion. Film thickness. In addition, actual measurement was performed using the coated stent after evaluating the softness | flexibility of the covered stent shown below.

  Table 1 shows the results of measuring the coating film thicknesses on the void portion 22, the outer peripheral surface side of the strut 21, and the inner peripheral surface side of the strut 21 for the coated stents of Examples, Comparative Example 1 and Comparative Example 2.

[Evaluation of flexibility of coated stent]
A resin hard tube having an inner diameter of 10 mm was oriented in the vertical direction and fixed in a vise so that one end of the tube protruded upward. The coated stent was fixed to the tube by inserting 50 mm of one end of the coated stent into the lumen of the tube. The center of the disk-shaped pressing jig having a diameter of 10 mm attached to the force gauge is placed at a position where the distance from the end of the tube of the coated stent is 20 mm, and the surface of the disk-shaped pressing jig is always on the covering stent. The coated stent is pressed with a disk-shaped pressing jig so as to be in contact with the vertical direction, and the displayed value of the force gauge at the time when the angle between the axis at the initial position and the axis after the movement becomes 60 degrees is represented by the coated stent. Recorded as a repulsive force. The same measurement was repeated by changing the position of the center of the disk-shaped pressing jig to the position of 40 mm and the position of 60 mm from the end of the tube of the coated stent.

  Table 2 shows the results of the above measurements for the coated stents of Examples and Comparative Example 2. It can be said that the lower the repulsive force, the higher the flexibility of the covered stent.

  As is apparent from Table 2, the coated stent of the example in which the coating film of the gap portion 22 is thin has higher flexibility than the coated stent of the coated stent of the comparative example 2 in which the coating film of the gap portion 22 is thick. It is. Therefore, the coated stent of the embodiment easily follows the curved body lumen, and the stent is displaced from the intended indwelling position, or restenosis is caused because the stent places a load on the body lumen. It can be said that this problem is unlikely to occur.

1 is an overall view showing an embodiment according to a covered stent of the present invention. It is a cross-sectional enlarged view of the covered stent shown in FIG. It is the schematic which shows one Embodiment which concerns on the manufacturing method of the covering stent of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Coated stent 20 Stent base material 21 Strut 21A Outer peripheral surface 22B Inner peripheral surface 22 Space | gap part 30 Coating film 40 Rotating shaft

Claims (6)

A cylindrical stent substrate formed by struts and having voids formed between the struts;
A coating film that covers at least a part of the outer periphery of the strut of the stent base material and is provided so as to fill the gap portion;
A coated stent in which the thickness of the coating film in the void is 1 μm to 40 μm.   2. The film thickness of the coating film on the strut surface on the outer peripheral surface side of the stent base material is 10% to 100% with respect to the film thickness of the coating film in the gap portion of the stent base material. Covered stent.   The coated stent according to claim 1 or 2, wherein the thickness of the coating film on the strut surface on the outer peripheral surface side of the stent base material is 1 µm to 20 µm.   The coated stent according to any one of claims 1 to 3, wherein a thickness of the coating film on the strut surface on the inner peripheral surface side of the stent base material is 0 to 20 µm.   The coating film of the strut surface on the inner peripheral surface side of the stent base material and the coating film of the void portion of the stent base material, or the strut surface and the stent base material on the inner peripheral surface side of the stent base material The coated stent according to any one of claims 1 to 4, wherein an inner peripheral surface of the stent base material formed by the coating film of the void portion is substantially smooth.   6. The coating film is formed on the stent base material by rotating the shaft while the stent base material is externally fitted to the shaft member, and attaching the resin solution to the stent base material that rotates axially. A method for producing a covered stent according to claim 1.

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