JP2019150077A - Stent - Google Patents

Abstract

To provide a stent capable of alleviating or preventing a problem caused by galvanic corrosion, and reducing a burden on a living body by a foreign material.SOLUTION: A stent 100 is configured so that a marker 120 formed of metal and having radiopacity is arranged in a stent body 110 formed of metal different from the aforesaid metal. The stent includes a polymer 130 capable of inhibiting conductivity between the marker and the stent body. At least one of the metal that forms the stent body and the polymer is a bioerodible material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a stent.

  Conventionally, a radiopaque marker is disposed on a stent body so that the position of the stent placed in the living body can be easily confirmed.

  The marker is made of a metal having a radiopacity higher than that of the stent body. In a stent in which the stent body is also made of metal, the metal forming the stent body and the marker. Is different.

  When such dissimilar metals come into contact with each other in a living body, galvanic corrosion occurs, and as a result, there is a risk that the stent body deteriorates. However, for example, a state in which a marker is embedded in a polymer as in Patent Document 1 In this case, direct contact between the stent body and the marker is less likely to occur.

  Further, in the above prior art, the stent body and the polymer are formed of a non-biodegradable material that does not degrade in vivo, and the stent body and the polymer are permanent while the marker is firmly held. Remains in vivo.

Special table 2008-503270 gazette

  However, they are foreign matter for the living body, and it is preferable to reduce such a foreign matter as much as possible after the lesion site is treated with the stent.

  The present invention has been made in view of this, and an object of the present invention is to provide a stent that can alleviate or prevent harmful effects caused by galvanic corrosion and can reduce the burden on a living body due to foreign substances.

  In order to achieve the above object, a stent of the present invention has a configuration in which a marker made of metal and having radiopacity is arranged on a stent body formed of a metal different from the metal. The stent of the present invention has a polymer capable of inhibiting conductivity between the marker and the stent body, and at least one of the metal forming the stent body and the polymer is biodegraded. Material.

  According to the stent having the above-described configuration, the electrical connection between the stent body and the marker is inhibited by the polymer, so that the adverse effects caused by galvanic corrosion can be prevented or alleviated. In addition, since at least one of the stent body and the polymer is hardly decomposed to become a foreign substance, the burden on the living body can be reduced.

It is a figure which shows the stent of embodiment. It is sectional drawing which follows the 2-2 line of FIG. It is a graph which compares and shows the magnitude of the corrosion rate about the stent of an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and differs from an actual ratio.

  As shown in FIG. 1, the stent 100 of the embodiment has a stent body 110, a marker 120, and a polymer 130. The stent 100 is used to treat a stenosis site or an occlusion site occurring in a living body lumen such as a blood vessel, a bile duct, a trachea, an esophagus, or a urethra.

  The stent body 110 is a member formed in a substantially cylindrical shape by a strut 111 that is a linear component, and can be expanded and contracted in a radial direction D1 of the cylindrical shape.

  How the struts 111 extend to form the stent body 110 is not particularly limited. For example, the stent body 110 may be formed by forming an endless annular body while the struts 111 are folded back in a wave shape, and a plurality of the annular bodies are connected in the axial direction D2 orthogonal to the radial direction D1. Alternatively, the stent main body 110 may be formed by the struts 111 being spirally extended around the axial direction D2 while being folded in a wave shape, and the struts 111 adjacent in the axial direction D2 being connected to each other.

  The stent body 110 expands at a stenosis site or an occlusion site in the living body lumen and supports them to maintain the patency of the living body lumen. The stent body 110 may be a self-expanding type that expands by its own elastic force, or may be a balloon expansion type that expands by a balloon catheter or the like.

  The stent body 110 is made of metal. The metal forming the stent body 110 is a biodegradable material that decomposes in vivo. Examples of the metal forming the stent body 110 include magnesium, zinc, iron, or an alloy containing an element selected from any of these.

  The markers 120 are disposed on both ends of the stent body 110 in the axial direction D2, but the present invention is not limited to this, and the markers 120 may be disposed on only one of these ends, or disposed between them. May be. The marker 120 is disposed in the hole 112 formed in the stent body 110.

  The marker 120 is radiopaque and can be visually recognized under fluoroscopy, for example. The position of the stent 100 in the living body lumen can be confirmed by the marker 120.

  The marker 120 is formed of a metal different from the metal forming the stent body 110. Examples of the metal forming the marker 120 include gold, platinum, iridium, tantalum, or an alloy containing an element selected from any of these. Alternatively, the marker 120 includes, for example, these radiopaque metal particles and biodegradable metals such as magnesium, zinc, iron, or an alloy containing an element selected from any of these. By combining them into a composite material, it may be configured to be disassembled.

  The polymer 130 is provided between the stent body 110 and the marker 120. The polymer 130 is provided between the stent body 110 and the marker 120 over the entire circumference of the hole 112, and holds the marker 120 while separating them so as not to contact at all.

  As shown in FIG. 2, the polymer 130 has an anchor portion 131 that extends to the outside of the hole 112. Anchor portion 131 extends from hole 112 to outer surface 113 of stent body 110. The outer surface 113 is an outer surface in contact with the living body lumen in the stent body 110.

  The polymer 130 has a function of inhibiting conductivity, more specifically, a function of inhibiting current flow. The polymer 130 is a biodegradable material.

  Examples of the polymer 130 include, but are not limited to, chitin, chitosan, poly (3-hydroxyvalylate), poly (lactide-co-glycolide), poly (3-hydroxybutyrate), and poly (4-hydroxybutyrate). Rate), poly (3-hydroxybutyrate-co-3-hydroxyvalerate), polyorthoester, polyanhydride, poly (glycolic acid), poly (glycolide), poly (L-lactide), poly (D, Polylactic acid such as L-lactide), poly (L-lactide-co-D, L-lactide), poly (caprolactone), poly (L-lactide-co-caprolactone), poly (D, L-lactide-co-) Caprolactone), poly (glycolide-co-caprolactone), poly (trimethylene carbonate), polyesteramide, poly (glycol) Lumpur acid - co - trimethylene carbonate), copoly (ether - ester), polyphosphazenes, biomolecules and the like.

  Next, the function and effect of this embodiment will be described.

  The stent 100 of the embodiment is placed in a living body lumen where a stenosis site or an occlusion site has occurred, and treats the living body lumen by supporting it in an open state for a predetermined period of time. Meanwhile, the electrical connection between the stent body 110 and the marker 120 is blocked by the polymer 130.

  Unlike the present embodiment, when the stent body 110 and the marker 120, which are not formed of the polymer 130 and are made of different metals, are in direct contact with each other, there is a possibility that an adverse effect due to galvanic corrosion may occur.

  Specifically, for example, the degradation of the stent body 110 progresses at an accelerated rate due to galvanic corrosion, and the biological lumen cannot be supported in an open state before a predetermined period required for treatment elapses, or the stent body 110 As a result of rapid corrosion, the pH tends to become basic, and as a result, there is a risk that inflammation will occur in the living body lumen at the place where the stent 100 is placed.

  On the other hand, in the present embodiment, since the polymer 130 inhibits the electrical connection between the stent body 110 and the marker 120, galvanic corrosion and, as a result, the above-described adverse effects caused by the galvanic corrosion can be reduced or prevented.

  In addition, since the stent body 110 is formed of a biodegradable material, the stent body 110 is decomposed and disappears after a predetermined period required for treatment, and hardly becomes a foreign substance. Therefore, the burden on the living body can be reduced.

  Furthermore, in the present embodiment, the polymer 130 is also a biodegradable material, which decomposes and disappears after treatment and hardly becomes a foreign substance. Therefore, the burden on the living body can be reduced more effectively.

  In addition, the acid generated by the decomposition of the polymer 130 neutralizes the basic inclination of the pH as the stent body 110 corrodes, so that it is possible to prevent inflammation in the living body lumen.

  The polymer 130 includes an anchor portion 131, thereby being caught on the outer surface 113 of the stent body 110. For this reason, even if the marker 120 held by the polymer 130 is pressed from the inner wall of the living body lumen, for example, even if a force is applied from the outer surface 113 side of the stent body 110 to the opposite inner surface side, the marker 120 is removed. hard.

<Example>
The present inventors actually produced the stent 100 and confirmed that galvanic corrosion was suppressed.

  In the actually produced stent 100 of the embodiment, the forming material of the stent body 110 is magnesium, the forming material of the marker 120 is tantalum, and the forming material of the polymer 130 is polylactic acid. Here, the thickness of the polymer 130 is 70 μm.

  Moreover, the present inventors produced two stents different from the stent 100 as Comparative Examples 1 and 2 to be compared with Examples.

  As Comparative Example 1, the present inventors produced a stent composed only of the stent body 110 from which the marker 120 and the polymer 130 were removed from the stent 100 of the example.

  In addition, as a comparative example 2, the present inventors produced a stent in which the polymer 130 is not provided and the marker 120 formed of tantalum is directly in contact with the hole 112 of the stent body 110 of the example. Table 1 below summarizes the schematic configurations of Examples and Comparative Examples 1 and 2.

  The inventors immersed the stent 100 of Example and the stents of Comparative Examples 1 and 2 in 50 ml of Hanks' liquid for about 6 hours, and observed the progress of corrosion. Here, the temperature of the Hanks solution is 37 ° C.

  When corrosion occurs in the Hank's solution in the stent body 110, hydrogen bubbles are generated. In the embodiment in which the polymer 130 is interposed between the stent body 110 and the marker 120, a comparative example including only the stent body 110. As in 1, it was confirmed that almost no hydrogen bubbles were generated and the progress of corrosion was suppressed.

  On the other hand, in Comparative Example 2 in which the stent body 110 and the marker 120 are in direct contact without the polymer 130, it was confirmed that hydrogen bubbles were generated vigorously and the progress of corrosion was accelerated.

  In fact, as shown in FIG. 3, when the corrosion rate is calculated from the amount of change in the weight of the stent when a predetermined time has elapsed, compared to Comparative Example 2 in which the stent body 110 and the marker 120 are in direct contact with each other, The corrosion rate of the example in which the polymer 130 is interposed is small, and is almost equal to that of the comparative example 1 including only the stent body 110. From this result, it was confirmed that the galvanic corrosion was actually suppressed by the polymer 130.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, in the above embodiment, both the metal forming the stent body 110 and the polymer 130 are biodegradable materials, but the present invention is not limited to this form, only one of them. It may be a biodegradable material, and the other may be a non-biodegradable material that remains without being degraded in vivo.

  As an example, the present invention includes a form in which the metal forming the stent body 110 is a biodegradable material similar to that in the above embodiment, and the polymer 130 is a non-biodegradable material.

  In this case, the polymer 130 of the non-biodegradable material is not limited to, for example, polyurethane, silicone, polyester, polyolefin, polyisobutylene and ethylene-alphaolefin copolymer, acrylic polymer and copolymer, vinyl halide polymer and copolymer. , Polyvinyl ether, poly (vinylidene halide), polyacrylonitrile, polyvinyl ketone, polyvinyl aromatic, polyvinyl ester, acrylonitrile-styrene copolymer, ABS resin, polyamide, polycarbonate, polyoxymethylene, polyimide, polyether, polyurethane, rayon, rayon-triacetate , Cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellophane, cellulose nitrate, cellulose propionate , Cellulose ether, carboxymethyl cellulose, ethylene vinyl alcohol copolymer, poly (butyl methacrylate), poly (vinylidene fluoride-co-hexafluoropropene), polyvinylidene fluoride, ethylene vinyl acetate copolymer, poly (vinyl acetate), styrene-isobutylene -Styrene-triblock copolymer, polyethylene glycol, etc. are mentioned.

  If the polymer 130 is a non-biodegradable material in the living body, the degradation of the polymer 130 is suppressed, and the separated state between the stent body 110 and the marker 120 is reliably maintained, so that galvanic corrosion can be more effectively mitigated or prevented. .

  As another modification, the present invention includes a form in which the metal forming the stent body 110 is a non-biodegradable material and the polymer 130 is a biodegradable material similar to the above-described embodiment. .

  In this case, the non-decomposable metal that forms the stent body 110 is not limited to the following, and examples thereof include biosafety metals such as stainless steel, cobalt alloys, and nickel alloys.

  In this way, if the metal forming the stent body 110 is a non-biodegradable material in the living body, the stent body 110 is prevented from being decomposed and the strength is unlikely to decrease, so that the patency state of the living body lumen can be more reliably established. Can be maintained.

  Further, the present invention includes a form in which the polymer is formed only on the inner peripheral surface of the hole 112 without the anchor portion 131.

100 stents,
110 stent body,
111 struts,
112 holes,
113 outer surface of the stent body,
120 markers,
130 polymer,
131 anchor part,
D1 radial direction of the stent body,
D2 Axial direction of the stent body.

Claims (6)

A marker formed of a metal and having radiopacity is disposed on a stent body formed of a metal different from the metal,
A stent having a polymer capable of inhibiting conductivity between the marker and the stent body, wherein at least one of the metal forming the stent body and the polymer is a biodegradable material .   The stent according to claim 1, wherein the metal forming the stent body is a biodegradable material.   The stent according to claim 2, wherein the polymer is a biodegradable material.   The stent according to claim 2, wherein the polymer is a non-biodegradable material that remains without being degraded in vivo.   The stent according to claim 1, wherein the metal forming the stent body is a non-biodegradable material that remains without being degraded in vivo, and the polymer is a biodegradable material. The stent body has a hole in which the marker is disposed,
The stent according to any one of claims 1 to 5, wherein the polymer has an anchor portion extending from the hole to an outer surface of the stent body.