KR100501649B1 - Vascular stents - Google Patents

Abstract

Vascular stents that are mounted in vessels such as blood vessels, lymphatic vessels, bile ducts, or urinary tracts. The vessel stents have a coronal body that constitutes one flow passage from one end to the other end, and both end sides of the central main body of the coronary body. Each of the low rigidity parts having a lower rigidity than the central main body is formed integrally with each other. The low rigidity portion is formed to have a Young's modulus close to the Young's modulus of the vessel of the living body on which the stent is mounted, thereby suppressing the occurrence of stress concentration in the vessel when inserted into the vessel.

Description

Vascular stents

The present invention is a vessel stent mounted in vessels such as blood vessels, lymph vessels, bile ducts and urine vessels, and the vessel stent is used to maintain the shape of the vessel in a constant state when mounted on the vessel.

Conventionally, in the case where a stenosis has occurred in a blood vessel of a living body, particularly an artery or the like, the vascular stenosis is formed by inserting a balloon forming portion placed near the distal end of the catheters to the constriction to form a balloon. Percutaneous angioplasty (PAT), which is a surgery to expand blood flow and improve blood flow, is performed.

However, even after percutaneous angioplasty, it is known that restenosis occurs with a high probability of stenosis.

In order to prevent such restenosis, a coronary stent is inserted into and mounted on a portion subjected to percutaneous angioplasty. As shown in Fig. 11, the stent 1 is embedded in the blood vessel 2 in an expanded state to support the blood vessel 2 therein, and to prevent the restenosis of the blood vessel 2 from occurring. .

According to a clinical example in which a stent formed by combining a wire rod made of stainless steel, which has been used conventionally, was inserted into a portion subjected to percutaneous angioplasty, restenosis occurred in about 15%.

In order to prevent such restenosis, a stent formed of polyma fiber containing a drug for preventing the occurrence of stenosis has been proposed in Japanese Patent Laid-Open No. 5-502179 (WO 91/01097).

By the way, the restenosis of the blood vessel after the stent mounting occurs a lot at the end of the stent or occurs at the end.

The stent used to be inserted into the blood vessel is formed to have sufficiently large rigidity as compared to the blood vessel to maintain the blood vessel in an expanded state. For example, the Young's modulus of blood vessels is about 3 × 10 ⁷ Pascals, while the Young's modulus of stainless steel, which is the main stent material used to keep the vessels expanded, is about 3 × 10 ¹¹ Pascals.

The stent 1 expanded and inserted into the blood vessel 2 is kept in the expanded state as shown in FIG. 11. At this time, the blood vessel 2 is reduced in diameter at positions corresponding to the respective ends 1a and 1b of the stent 1, which are not supported by the stent 1. At this time, the part supported by each end part 1a, 1b of the stent 1 of the blood vessel 2 turns into a stress concentration part.

And the blood vessel 1, especially an artery, is always repeating a beat in order to flow blood. Therefore, the load is repeatedly applied based on the pulsation of the stress concentration portion of the blood vessel 2 supported at each end 1a, 1b of the stent 1. As a result, the inner wall of the blood vessel 2 may be damaged by the end portions 1a and 1b of the stent 1. When a load is applied to the stress concentration portion supported on the inner wall of the blood vessel 2, damage occurs from the inner film of the blood vessel 2 or the inner film of the blood vessel 2 to the outer film. When the blood vessel 2 is damaged, the blood vessel 2 repairs the damage by a biological reaction. When repairing the damage, the blood vessel 2 may overgrow the inner lining and cause restenosis.

1 is a perspective view showing a stent for a vasculature according to the present invention.

FIG. 2 is a cross-sectional view of the vessel stent shown in FIG. 1. FIG.

Fig. 3 is a perspective view showing a state where the vessel stent shown in Fig. 1 is inserted into a blood vessel.

FIG. 4 is a cross-sectional view showing the state when the vessel stent shown in FIG. 1 is inserted into a blood vessel and the blood vessel is pulsating.

5 is a perspective view showing another example of the vessel stent according to the present invention.

FIG. 6 is a cross-sectional view showing another example of the vascular stent according to the present invention, in which the low rigidity portion formed at each end of the tubular body is gradually reduced in diameter.

7 is a cross-sectional view showing a stent for vasculature according to the present invention in which a tubular body is formed of a polymeric material.

Fig. 8 is a perspective view showing the vessel stent according to the present invention formed by woven a tubular body with a thin metal wire or a polymame yarn.

Fig. 9 is a perspective view showing a stent for vasculature according to the present invention in which a reinforcing member is provided in a central main body portion of a tubular body formed by woven with thin metal wire or polymaed yarn.

Fig. 10 is a cross-sectional view showing a thin metal wire or a polymer made of a metal forming the central main body of the tubular body.

11 is a perspective view showing a state where a conventional vessel stent is inserted into a blood vessel.

It is an object of the present invention to provide a novel vessel stent that can solve the problems of the conventional vessel stent.

Another object of the present invention is to provide a stent for a vasculature which can reliably prevent damage to the vasculature while reliably maintaining an expanded state of a living vessel such as a blood vessel.

It is still another object of the present invention to provide a stent for vasculature, which makes it possible to insert and mount a stress vessel without generating a stress concentration portion.

Vascular stent according to the present invention proposed to achieve the above object has a tubular body constituting one flow passage from one end to the other end side and the central main body portion on both ends of the central main body portion of the tubular body Each of the lower rigidity parts having lower rigidity is integrally formed. The low rigidity portion is formed to have a Young's modulus close to the Young's modulus of the vessel of the living body on which the stent is mounted.

The low rigidity portion is formed by extending both ends of the tubular body to increase the thickness.

The low rigidity portion is formed by setting both ends of the tubular body at a lower surface density with respect to the central body portion having a predetermined surface density. In the case where the tubular body is formed by weaving or weaving a metal thin wire or a polymaze thread, it is formed by lowering the nose or nose precision of both ends of the tubular body.

The low rigidity portion is formed by forming both ends of the tubular body by using a material having a Young's modulus lower than that of the material forming the central main portion.

By forming the coronal body using a bioabsorbable polymer yarn, the stent can be absorbed and removed by living body tissues several months before and after insertion after maintaining the shape for several weeks to several months after insertion into the vessel.

In the case where the tubular body is formed of a thin metal wire or a polymer made of thread, the wire body constituting the both ends is formed of a soft wire body having a smaller strength than the wire body constituting the central main body. The low rigidity part is comprised in the both ends of a tubular body by using

EMBODIMENT OF THE INVENTION Hereinafter, the vessel stent concerning this invention is demonstrated concretely with reference to drawings.

As shown in Fig. 1, the vascular stent 11 according to the present invention is used by being inserted into a blood vessel, for example, a coronary artery, to form a tubular body constituting one flow channel from one end to the other end ( 12) This tubular body 12 is formed using the stainless steel which is excellent in corrosion resistance and biocompatible.

As the metal constituting the tubular body 12, stainless steel, nickel-titanium alloy, pratina, tantalum and platinum can be used.

The tubular body 12, when inserted into the blood vessel, has a central body portion 13 having rigidity sufficient to keep the blood vessel in an expanded state. On both ends of the central main body 13, low rigidity parts 14 and 15 having lower rigidity than the central main body 13 are integrally formed. These low rigidity parts 14 and 15 are formed by making both ends of the tubular body 12 thinner than the thickness of the central body 13.

The low rigidity portions 14 and 15 having a thin thickness are formed by cutting or forging both ends of the tubular body 12. At this time, as shown in FIG. 2, it is preferable that the low rigidity parts 14 and 15 are formed so that thickness may become thin gradually toward the edge part of the tubular body 12 from the central main part 13 of thickness. That is, the tubular body 12 is provided with the low rigidity parts 14 and 15 which become low rigidity gradually toward the both ends from the center main body part 13 side.

At this time, the central portion 12 is formed to have a sufficiently large Young's modulus compared to the Young's modulus of the blood vessel to maintain the blood vessel in which the stent 11 is inserted in an expanded state. Since the Young's modulus of the blood vessel into which the stent 11 is inserted is about 3 × 10 ⁷ Pascals, the central portion 12 is formed to have a Young's modulus of about 3 × 10 ¹¹ Pascals. The low rigidity portions 14 and 15 are formed to have a Young's modulus that is approximately equal to or slightly larger than the Young's modulus of blood vessels.

As shown in FIG. 3, the stent 11 using the tubular body 12 having the low rigidity portions 14 and 15 formed at both ends of the central body portion 13 having high rigidity as described above is inserted into the blood vessel 16. When mounted, the vessel 16 can be kept in an expanded state by the central body 12 having high rigidity.

Blood flows through the stent 11 and into the blood vessel 16. In addition, the blood vessel 16 pulsates, and expands and repeats the shaft diameter, thereby imparting a load as reduced against the stent 11. At this time, the low rigid portions 14 and 15 formed at both ends of the tubular body 12 are easily elastically displaced by the pulsation of the blood vessel 16, as shown in FIG. That is, the low rigidity portions 14 and 15 can be elastically displaced so as to gradually shrink from the central main body 13 toward each end portion of the tubular body 12, thereby preventing the occurrence of stress concentration in the blood vessel 16. .

The stent 11 configured as described above can prevent the damage of the blood vessel 16 and prevent damage to the blood vessel 16 when the stent 11 is inserted into and mounted on the blood vessel 16. Based on this, occurrence of restenosis can be suppressed.

Further, as shown in FIG. 5, a plurality of minute perforations 16 are laid on each end side of the tubular body 12 having an equal thickness, and the density of each end is made smaller than the density of the central body 13. Thereby, the low rigidity parts 14 and 15 which are lower in rigidity than the center main body part 13 are formed in each end part of the tubular body 12. As shown in FIG. At this time, it is preferable that the micropores 16 constituting the low rigidity portions 14 and 15 are laid so that the number gradually increases from the central main body portion 13 toward each end portion. By laying the micropores 16 in this manner, the low rigidity portions 14 and 15 gradually decrease in rigidity from the central body portion 13 toward each end portion.

Further, the plurality of micropores 16 are laid so that the diameter of the hole gradually increases from the central main body 13 toward each end, so that the rigidity of the low rigidity parts 14 and 15 is moved from the central main body 13 to each end. It can be made small gradually toward.

And as shown in FIG. 6, the low rigidity parts 14 and 15 formed in each edge part of the tubular body 12 are preferably formed so that it may be gradually reduced toward the edge part from the center main body part 13 side. By forming the tubular body 12 as described above, when the stent 11 is inserted into the blood vessel 16, the blood vessel expanded by the central main body 13 is gradually reduced along the low rigid portion 14 and 15 where the blood vessel is reduced. It is possible to reliably suppress the occurrence of the portion where the stress is concentrated.

The stent 11 is formed of a metal like stainless steel, but may be made of a polymer material.

As shown in FIG. 7, the stent 21 using this polymer material is formed by tubular shape of a polymer material, or a tubular body formed by tubular formation of a sheet material made of a polymer material. Has (22).

As the polymer material constituting the tubular body 22, a material having biocompatibility is selected, and in particular, one having bioabsorbability is selected. Polylactic acid (PLA), polyglycolic acid (PGA), polyglycine (polyglycolic acid, polylactic acid copolymer), polydioxanone, polyglyconate (trimetalene carbonate, glycolide) Copolymer), polyglycolic acid or polylactic acid, and an epsilon -caflolactone copolymer. The stent 11 formed of the polymer material having such a bioabsorbability can be absorbed and lost in living tissues several months after insertion, in which it maintains its shape for several weeks to several months after insertion into the blood vessel.

The tubular body 22 constituting the stent 21 also has a central main body 23 having rigidity sufficient to keep the blood vessel in an expanded state when inserted into the blood vessel as shown in FIG. On both ends of the central body portion 23, low rigidity portions 24 and 25 having lower rigidity than the central body portion 23 are integrally formed. These low rigidity parts 24 and 25 are formed by making both ends of the tubular body 22 thinner than the thickness of the central body 13.

Such thin, low rigid portions 24 and 25 are formed by extending both ends of the tubular body 12.

The stent 21 using the polymer material may also form the low rigidity portions 24 and 25 by laying micropores at each end of the tubular body 22 in the same manner as using the metal described above. The low rigidity portions 24 and 25 are preferably formed to be gradually reduced in diameter toward the end portion from the central main body portion 23 side.

In addition, the stent according to the present invention can be formed by weaving a metal thin wire or a polymer made of yarn.

Next, a stent using a thin metal wire will be described with reference to the drawings.

As shown in FIG. 8, the stent 31 has a tubular body 33 formed by woven together thin wires 32 made of metal such as stainless steel, nickel-titanium alloy, platinum, tantalum, and platinum having biocompatibility. . This tubular body 33 is formed in the shape of a nose by combining the fine wire 32 made of one metal, ie, it is woven so as to form a loop by the fine wire 33.

The coronal body 33 has a central main body portion 34 having rigidity sufficient to keep the blood vessels in an expanded state when inserted into the blood vessel. On both ends of the central main body 34, low rigidity parts 35 and 36 having lower rigidity than the central main body 34 are integrally formed. These low rigidity portions 35 and 36 are formed by making the nose density rougher than the central main body portion 34 having a predetermined nose density. At this time, the low rigidity portions 35 and 36 are preferably woven so as to gradually reduce the precision of the nose toward the end of the tubular body 33 in the central body portion 34.

In addition, the central portion 34 is assembled to have a nose of a density sufficient to obtain a sufficiently high Young's modulus compared to the Young's modulus of the blood vessel to maintain the vessel in the expanded state when the stent 31 is inserted into the vessel, 35, 36) are framed to have a nose whose density is approximately equal to the Young's modulus of blood vessels or sufficient to obtain a slightly higher Young's modulus.

In order to form the stent 31 having low rigidity portions 35 and 36 with lower rigidity than the central main body portion 34 on the end side of the tubular body 33, the entire coronal body 33 is also approximately equal to the Young's modulus of blood vessels. The fine metal wire 32 is woven at the density of the nose to have the same or slightly higher Young's modulus. And as shown in FIG. 9, the reinforcement part 37 which laminated | stacked the polymeric material is provided in the center main body part 34 of the tubular body 33, and rigidity is improved. At this time, the polymer material constituting the reinforcing portion 37 is laminated so that the central main portion 34 has sufficient rigidity to maintain the vessel in an expanded state.

The reinforcement part 37 is formed by outer-out forming a polymeric material in the tubular body 33 which formed the fine metal wire 32 together. That is, the reinforcement part 37 is formed by injection-molding a polymeric material to the tubular body 33 arrange | positioned in the shaping | molding die.

Further, in order to increase the rigidity of the central main body 34 of the tubular body 33, the fine metal wire 32 may be interwoven into the central main body 34.

As illustrated in FIG. 8 described above, the woven stent 31 may be formed by using a yarn made of polymer. This thread is formed by pulling out a fiber made of polymer.

At this time, the stent 31 composed of the tubular body 33 interwoven with a bioabsorbable polymar filament is retained its shape for several weeks to several months after being inserted into a blood vessel. It can be absorbed and lost.

The bioabsorbable polymer may include polylactic acid (PLA), polyglycolic acid (PGA), polyglycotin (polyglycolic acid, polylactic acid copolymer), polydioxanone, polyglyconate (trimetalene carbonate, glycolide air) Copolymer), polyglycolic acid or polylactic acid, and an epsilon -caflolactone copolymer.

It is possible to mix various chemical | medical agents in the yarn made of polyma fiber. Therefore, by incorporating an X-ray impermeable agent at the time of spinning the fiber, the state of the vessel stent inserted into the blood vessel can be observed by X-ray, and a thrombolytic or antithrombotic agent such as heparin, urokinase or t-PA is mixed. It is also valid.

The stent 31 described above is basically formed by weaving a single metal thin wire or a polymer made of a substantially uniform size, but by varying the size of the thin wire or the yarn, the stent 31 has a high rigidity. It can be comprised by the tubular body 33 which has the low rigidity parts 35 and 36 with low rigidity at an edge part. That is, the central main body 34 of the tubular body 33 is formed by a highly rigid thin wire or thread, and each end of the tubular body 3 is compared with the thin wire or thread which constitutes the central main body 34. The low rigidity parts 35 and 36 are formed in each end part of the tubular body 33 by weaving with thin wire | wire or a thread with a low rigidity.

The low rigidity portions 35 and 36 are formed at each end of the tubular body 33 by changing the cross-sectional shape of the thin wire or thread constituting the central main body 34 and the thin wire or thread constituting each end of the tubular body 33. May be formed. In other words, the cross-sectional shape of the thin wire or the yarn constituting each end of the tubular body 33 is made flat so as to lower the rigidity. Alternatively, the cross-sectional shape of the thin wire 32 or the thread 42 constituting the central main body 34 of the tubular body 33 may be increased in rigidity compared to the section line or thread constituting each end of the tubular body 33. For example, as shown in FIG. 10, it forms so that cross section H shape may be formed.

In addition, when the tubular body 33 is formed by woven with thin metal wire or polymaid yarn, the number of thin wires or yarns when woven together is reduced as the central main body part 34 reaches each end. As a result, the low rigid portions 35 and 36 may be formed at each end of the tubular body 33.

The stent according to the present invention can be used not only for blood vessels but also for vessels of living bodies such as lymphatic vessels, bile ducts, and urine tubes.

As described above, the vessel stent according to the present invention is constituted by a tubular body in which low rigidity portions having low rigidity are integrally formed at both end sides of the central main body portion, so that the vessel can be reliably maintained in an expanded state. It is possible to suppress the occurrence of stress concentration in the vessel. Therefore, according to the vessel stent concerning this invention, the effective effect that the inflammation, excess thickening, etc. of a vessel can be prevented and restenosis can be prevented can be acquired.

Claims (18)

In the stent for vasculature mounted in the vasculature of the human body, It has a tubular body constituting one flow path from one end to the other end side, The tubular body is a vessel stent formed by forming a central body portion and a low rigidity portion having lower rigidity than the central body portion, respectively, on both ends of the central body portion. The method of claim 1, The tubular body is a vessel stent, characterized in that it consists of a central main body portion having a predetermined thickness, and a low rigidity portion gradually thinned from the central main body portion toward each end. The method of claim 1, The tubular body is a vessel stent, characterized in that the surface density of both ends is set lower than the central main body portion having a predetermined surface density. In accordance with claim 2, The tubular stent for the vessels, characterized in that formed by a metal. The method of claim 2, The tubular stent for the vessels, characterized in that formed by a polymeric material. The method of claim 1, The tubular body is a stent for a vessel, characterized in that the central main body portion is formed of a metal, the low rigidity portion is formed of a polyma material. In the stent for vasculature mounted in the vasculature of the human body, With a tubular body constituting one flow path from one end to the other end, The tubular body is a vessel stent, in which a central main body portion of a metal wire mesh is formed in a mesh shape, and a low rigidity portion having a lower rigidity than the central main body portion is integrally formed on both ends of the central main body portion. The method of claim 7, wherein The tubular body has a low stiffness portion formed by making the density of the nose smaller than the central body portion at both ends of the central body portion having a predetermined nose density. The method of claim 7, wherein The tubular body is a stent for vascular vessels, wherein low-rigidity portions are formed on both ends of the central main body by laminating a polyma material in the central main body. The method of claim 7, wherein The vessel stent according to claim 1, wherein the low rigidity portion is formed of a polymer material. The method of claim 7, wherein The tubular body is composed of a central main body portion of the fine metal wire mesh is formed in a mesh shape, and a low-stiffness portion formed by tubularly squeezing the polymer fibers successively to the central main body portions on both ends of the central main body portion. Vascular stent. In the stent for vasculature mounted in the vasculature of the human body, With a tubular body constituting one flow path from one end to the other end, The tubular body is a vessel stent, each of which is formed by forming a central main body portion that is made of a polymer made of tubular yarn, and a low rigidity portion having a lower rigidity than the central main body portion on both ends of the central main body portion. The method of claim 12, The tubular body has a low stiffness portion formed by forming a lower rigidity portion of the central main body portion having a predetermined nose density by making the density of the nose smaller than that of the central main body portion. The method of claim 12, The tubular body is a stent for vascular vessels, wherein low rigidity is formed at both ends of the central main body by laminating a polyma material in the central main body. The method of claim 12, The yarn of the polymerase is stent for vasculature, characterized in that formed by a bioabsorbable polymer. In the stent for vasculature mounted in the vasculature of the human body, With a tubular body constituting one flow path from one end to the other end, The tubular body is composed of a central main body portion that tubularly sculpts a linear body having a predetermined strength, and a low rigidity portion that is squeezed by a flexible linear body of less strength than the linear body that is continuously joined to both ends of the central main body portion. Vascular stent. The method of claim 16, Said linear body is a thin wire made of metal. The method of claim 16, The tubular stent for a vasculature, characterized in that the yarn made of polyma.