Artificial blood vessel and method of producing artificial blood vessel

Abstract

To provide an artificial blood vessel capable of improving blood leakage resistance while maintaining flexibility.SOLUTION: An artificial blood vessel VE comprising weft yarns 2 and warp yarns 1 composed of multifilament yarns, the artificial blood vessel VE comprises: a first region R1 woven in a plain weave; a second region R2 including second region-side first parts R21 where the warp yarns 1 straddle the plurality of weft yarns 2, and second region-side second parts R22 where the warp yarns 1 extend across one weft yarn 2; and a third region R3 including third region-side first parts R31 where the warp yarns 1 straddle the plurality of weft yarns 2 and third region-side second parts R32 where the warp yarns 1 extend across one weft yarn 2. The second region-side first parts R21 and the third region-side first parts R31 include covering portions, and the covering portions are configured to be movable relative to the surfaces of the warp yarns 1 disposed between the pair of second region-side first parts R21 and between the pair of third region-side first parts R31.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vascular graft and a method for producing the same. [Background technology]

[0002] Artificial blood vessels are used, for example, to replace diseased biological blood vessels. As shown in Patent Document 1, for example, artificial blood vessels are constructed with a woven structure of warp threads and weft threads. Artificial blood vessels are required to have low blood leakage from the artificial blood vessel, i.e., high blood leakage resistance. The blood leakage resistance of artificial blood vessels can be improved by increasing the weaving density of the warp threads and weft threads. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-139498 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, while increasing the weave density of an artificial blood vessel can improve the resistance to blood leakage, it impairs the flexibility required of the artificial blood vessel.

[0005] Therefore, an object of the present invention is to provide an artificial blood vessel capable of improving blood leakage resistance while maintaining flexibility, and a method for producing the artificial blood vessel. [Means for solving the problem]

[0006] The artificial blood vessel of the present invention has weft yarns and warp yarns made of multifilament yarns, and the artificial blood vessel has a first region in which the warp yarns and the weft yarns are woven in a plain weave, a second region having a first portion on a second region side where the warp yarns cross over a plurality of weft yarns on one surface of the artificial blood vessel and a second portion on the second region side where the warp yarns extend across one weft yarn, and a third region having a second portion on a second region side where the warp yarns extend across one weft yarn on one surface of the artificial blood vessel. a third region having a third region first portion and a third region second portion in which the warp extends across one weft, the third region having a third region first portion and a third region having a third region second portion in which the warp extends across one weft, the second region first portion being adjacent to the third region second portion in the extension direction of the weft, the second region second portion being adjacent to the third region first portion in the extension direction of the weft, the second region first portion and the third region first portion being adjacent to the second region first portion and the The artificial blood vessel has a covering portion formed by a melted and solidified state of the multifilament yarn on the surface of the third region side first portion, or a resin layer coated on the surface of the multifilament yarn, the covering portion covering the multifilament yarn in the second region side first portion and the third region side first portion in a planar manner, the covering portion spreading in the extension direction of the weft yarn so as to cover at least a portion of the surface of the warp yarn arranged between the pair of the second region side first portions in the extension direction of the weft yarn and the surface of the warp yarn arranged between the pair of the third region side first portions in the extension direction of the weft yarn, and the covering portion is configured to be able to move radially of the artificial blood vessel relative to the surface of the warp yarn arranged between the pair of the second region side first portions in the extension direction of the weft yarn and the surface of the warp yarn arranged between the pair of the third region side first portions in the extension direction of the weft yarn in response to the movement of the artificial blood vessel.

[0007] The method for producing an artificial blood vessel of the present invention is a method for producing an artificial blood vessel having weft yarns and warp yarns composed of multifilament yarns, the method including: a first region in which the warp yarns and the weft yarns are woven in a plain weave; a second region on one surface of the artificial blood vessel having a first portion on a second region side where the warp yarns cross over a plurality of weft yarns and a second portion on the second region side where the warp yarns extend across a single weft yarn; a third region on one surface of the artificial blood vessel having a first portion on a third region side where the warp yarns cross over a plurality of weft yarns and a second portion on the third region side where the warp yarns extend across a single weft yarn; a third region having a third region-side second portion extending across the weft, and a third region having a third region-side second portion alternately arranged in an extending direction of the weft; and a heating medium is brought into contact with a surface of the base material that will become an outer surface of the artificial blood vessel, thereby melting and solidifying the multifilament yarns on the surfaces of the second region-side first portion and the third region-side first portion, or by coating a resin layer on the surfaces of the second region-side first portion and the third region-side first portion, thereby solidifying the multifilament yarns on the surfaces of the second region-side first portion and the third region-side first portion. the step of forming a covering portion that covers a surface of a warp yarn in a planar manner; the step of forming a tubular body by processing the base material into a tubular shape; the step of accommodating the tubular body in a container having a compression element and applying spot-like pressure to the radially inward direction of the tubular body by the compression element arranged between the inner surface of the container member and the outside of the tubular body; and the step of heating the compression element in a state in which the tubular body is pressed in spot-like manner radially inward, thereby deforming the surface of the covering portion into a shape in a pressurized state, wherein the covering portion extends in the extension direction of the weft yarn so as to cover at least a portion of the surface of the warp yarn arranged between the pair of second region side first portions in the extension direction of the weft yarn and the surface of the warp yarn arranged between the pair of third region side first portions in the extension direction of the weft yarn, and the covering portion is configured to be movable in the radial direction of the artificial blood vessel relative to the surface of the warp yarn arranged between the pair of second region side first portions in the extension direction of the weft yarn and the surface of the warp yarn arranged between the pair of third region side first portions in the extension direction of the weft yarn in response to the movement of the artificial blood vessel. Effect of the Invention

[0008] According to the artificial blood vessel and the method for producing the artificial blood vessel of the present invention, it is possible to improve the blood leakage resistance while maintaining flexibility. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of an artificial blood vessel according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a partial enlarged view of region II in FIG. [Diagram 3] FIG. 2 is a woven fabric diagram showing an example of the woven structure of a base material used in the artificial blood vessel of FIG. 1. [Figure 4] 4 is a schematic cross-sectional view of a base material obtained by cutting the base material along line IV-IV in FIG. [Diagram 5] 4 is a schematic cross-sectional view of a base material obtained by cutting the base material along line VV in FIG. [Figure 6A] 1 is a 30x SEM photograph of the surface of the artificial blood vessel of this embodiment taken in the radial direction of the artificial blood vessel. [Figure 6B] FIG. 6B is a 100x SEM photograph of the surface of the artificial blood vessel in FIG. 6A taken obliquely. [Figure 6C] 13 is a 30x SEM photograph of the surface of an artificial blood vessel according to another embodiment taken in the radial direction of the artificial blood vessel. [Figure 7] FIG. 2 is a schematic diagram showing a state in which a covering portion provided on one warp thread covers another warp thread. [Figure 8] FIG. 2 is a schematic diagram showing a portion where a covering portion provided on one warp thread covers another warp thread, cut in the extending direction of the weft thread. [Figure 9] FIG. 9 is a schematic diagram showing a state in which a covering portion of one warp thread and another warp thread move relative to each other when a radially outward force is applied to the inner surface of the artificial blood vessel from the state shown in FIG. 8. [Figure 10] 1 is a photograph of the artificial blood vessel of this embodiment when visible light is transmitted through it. [Figure 11] This is a schematic diagram showing a state in which a cylindrical body is placed on the outside of a molding core material and a winding member is partially wrapped around the outside of the cylindrical body to form peaks and valleys in an artificial blood vessel. [Figure 12]1 is a schematic diagram showing a state in which a cylindrical body is disposed on the outside of a molding core material, as viewed in the axial direction. FIG. [Figure 13] 13 is a diagram showing an example of the configuration of a housing member that houses a tubular body and a compression element arranged outside a molding core in order to pressurize the tubular body. FIG. [Figure 14] FIG. 4 is a schematic view showing the inside of a housing member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an artificial blood vessel according to one embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is merely an example, and the artificial blood vessel of the present invention is not limited to the following embodiment.

[0011] In this specification, the terms "perpendicular to A" and similar expressions do not only refer to a direction completely perpendicular to A, but also refer to a direction that is approximately perpendicular to A. In this specification, the terms "parallel to B" and similar expressions do not only refer to a direction that is completely parallel to B, but also refer to a direction that is approximately parallel to B. In this specification, the terms "C-shape" and similar expressions do not only refer to a perfect C-shape, but also refer to a shape that visually resembles a C-shape (approximately a C-shape).

[0012] Fig. 1 is a side view of an artificial blood vessel according to one embodiment of the present invention. Fig. 2 is a partially enlarged view of region II of the artificial blood vessel in Fig. 1. Fig. 3 is a woven fabric diagram showing an example of the woven structure of a base material used in the artificial blood vessel in Fig. 1.

[0013] The artificial blood vessel is used, for example, to replace a diseased biological blood vessel and to bypass the biological blood vessel. As shown in Figs. 1 and 2, the artificial blood vessel VE of this embodiment has peaks M and valleys V alternately formed in the direction of the axis X (see Fig. 1) of the artificial blood vessel VE. When the peaks M and valleys V are alternately formed in the artificial blood vessel VE, the artificial blood vessel can be flexible and is less likely to kink when bent. In this specification, for convenience of explanation, the portion radially outward (upper side in Fig. 2) from the midpoint between the top Mt of the peak M (see Fig. 2) and the bottom Vb of the valley V (see Fig. 2) in the radial direction of the artificial blood vessel VE is called the peak M, and the portion radially inward (lower side in Fig. 2) from the midpoint between the top Mt of the peak M and the bottom Vb of the valley V is called the valley V. In this embodiment, the artificial blood vessel VE is formed in a cylindrical shape with the peaks M and valleys V formed in a spiral shape, but the artificial blood vessel does not necessarily have to have the peaks M and valleys V.

[0014] The diameter of the artificial blood vessel VE can be changed depending on the site to be used, and is not particularly limited. For example, the artificial blood vessel VE may be a large-diameter artificial blood vessel with an inner diameter of 10 mm or more (for the thoracic and abdominal aorta), a medium-diameter artificial blood vessel with an inner diameter of 6 mm or more and less than 10 mm, such as 6 mm or 8 mm (for the arteries in the lower limbs, neck, and axillary regions), or a small-diameter artificial blood vessel with an inner diameter of less than 6 mm. The thickness of the artificial blood vessel VE is appropriately changed depending on the inner diameter and length of the artificial blood vessel to be used, and is not particularly limited. For example, the thickness of the artificial blood vessel VE can be 0.1 to 2 mm.

[0015] The length of the artificial blood vessel VE in the axial direction X can be changed depending on the site where it is used, and is not particularly limited. For example, the length of the artificial blood vessel VE in the axial direction X can be 100 to 1000 mm. When the artificial blood vessel VE is to be transplanted to a desired site, it is cut to a predetermined length by a doctor or the like. Depending on the site where it is to be transplanted, the artificial blood vessel VE may be cut perpendicular to the axial direction X, or may be cut obliquely at a predetermined angle to the axial direction X.

[0016] When the artificial blood vessel VE has peaks M and valleys V, the number of peaks M (or valleys V) (the number of pleats) of the artificial blood vessel VE is not particularly limited, but can be appropriately set according to the required kink performance. For example, the number of peaks M (the number of pleats) of the artificial blood vessel VE can be 20 to 70, preferably 25 to 35 per 100 mm of length in the axial direction X, in the case of an artificial blood vessel with an outer diameter of 15 mm. In addition, the interval (pitch) in the axial direction X between the top Mt of the peak M of the artificial blood vessel VE (see FIG. 2) and the top Mt of the adjacent peak M is not particularly limited, but can be, for example, 10 to 30% of the outer diameter of the artificial blood vessel VE (the outer diameter at the top Mt of the peak M), preferably 15 to 25%. In addition, the depth from the top Mt of the peak M to the bottom Vb of the valley V (see FIG. 2) is not particularly limited, but can be, for example, 5 to 20% of the outer diameter of the artificial blood vessel VE, preferably 5 to 15%.

[0017] In this embodiment, the curvature at the apex Mt of the peak M is smaller than the curvature at the bottom Vb of the valley V (in this embodiment, the radius of curvature at the apex Mt of the peak M is larger than the radius of curvature at the bottom Vb of the valley V). Note that "the curvature at the apex Mt of the peak M is smaller than the curvature at the bottom Vb of the valley V" means that the degree of curvature along the axis X at the apex Mt of the peak M is smaller than the degree of curvature along the axis X at the bottom Vb of the valley V (the curve of the peak M is gentler than the curve of the valley V), and the peak M and the valley V do not need to form a complete arc surface. If the curvature at the apex Mt of the peak M is smaller than the curvature at the bottom Vb of the valley V, when an external force is applied to the artificial blood vessel VE, stress is concentrated at the valley V, and the artificial blood vessel VE is likely to bend starting from the valley V. The curvature of the peaks M and valleys V is not particularly limited. For example, the radius of curvature of the tops Mt of the peaks M can be 5 to 8% of the diameter of the artificial blood vessel VE (and larger than the radius of curvature of the bottoms Vb of the valleys V). The radius of curvature of the bottoms Vb of the valleys V can be 2 to 3% of the diameter of the artificial blood vessel VE (and smaller than the radius of curvature of the tops Mt of the peaks M). By making the artificial blood vessel VE easier to bend, the curved artificial blood vessel VE is less likely to return to its original shape, and the load on the connection site between the artificial blood vessel VE and a blood vessel, etc., can be reduced.

[0018] The curved portion at the top Mt of the peak M and the curved portion at the bottom Vb of the valley V can be connected by a flat portion PL (see FIG. 2). This can improve flexibility and kink resistance compared to when the curved portions are directly connected to each other. The angle θ between the flat portion PL1 on one side and the flat portion PL2 on the other side can be set to 20° to 40°, preferably 30°, and the angle θ between the flat portion PL1 on one side and the flat portion PL2 on the other side can be appropriately set depending on the diameter of the artificial blood vessel, the height of the peaks, the height of the valleys, the pitch, etc.

[0019] Next, the structure of the base material constituting the artificial blood vessel VE will be described.

[0020] The artificial blood vessel VE of this embodiment has a predetermined weaving structure in which warp threads 1 and weft threads 2 are woven. In this embodiment, the artificial blood vessel VE has weft threads 2 and warp threads 1 made of multifilament yarns. In this embodiment, of the warp threads 1 and weft threads 2 constituting the artificial blood vessel VE, at least the warp threads 1 are made of multifilament yarns including a plurality of filament yarns. The weft threads 2 may be made of multifilament yarns or monofilament yarns. The predetermined weaving structure of the artificial blood vessel VE will be described later.

[0021] In this embodiment, as shown in Fig. 3, the artificial blood vessel VE has warp threads 1a-1l (hereinafter collectively referred to as warp threads 1) extending along the axial X direction (vertical direction in Fig. 3) and weft threads 2a-2l (hereinafter collectively referred to as weft threads 2) extending along the circumferential direction of the artificial blood vessel VE (horizontal direction in Fig. 3). More specifically, as shown in Fig. 3, the artificial blood vessel VE has a plurality of warp threads 1a-1l and a plurality of weft threads 2a-2l, and has a woven structure in which the warp threads 1 and the weft threads 2 are intertwined. In Fig. 3, the warp threads 1 extend in the vertical direction, and the extending direction of the warp threads 1 (axial X direction of the artificial blood vessel VE) is referred to as D1. In Fig. 3, the weft threads 2 extend in the horizontal direction, and the extending direction of the weft threads 2 (circumferential direction of the artificial blood vessel VE) is referred to as D2. In Fig. 3, the black parts (dotted parts) are the parts where the warp threads 1 appear on the outer surface (front surface) of the artificial blood vessel VE, and the white parts are the parts where the weft threads 2 appear on the outer surface of the artificial blood vessel VE. The loom for manufacturing the artificial blood vessel VE is not particularly limited.

[0022] As described later, in this embodiment, the warp threads 1 have portions R21, R31 extending across multiple weft threads 2 (see Figs. 3 and 5). Specifically, as shown in Fig. 3, the warp threads 1 have portions R21, R31 extending across multiple weft threads 2, and portions R1, R22, R32 extending across a single weft thread 2. In addition, the weave structure of the artificial blood vessel VE is not necessarily limited to the weave structure shown in Fig. 3, and may have other weave structures.

[0023] In this embodiment, the artificial blood vessel VE has a first region R1 in which warp threads 1 and weft threads 2 are woven in a plain weave, as shown in Fig. 3. The artificial blood vessel VE also has a second region R2 on one surface of the artificial blood vessel VE (in this embodiment, the outer surface (front surface) of the artificial blood vessel VE), which has a second region side first portion R21 (portion extending across multiple weft threads 2) where the warp threads 1 extend across multiple weft threads 2, and a second region side second portion R22 (portion extending across one weft thread 2) where the warp threads 1 extend across one weft thread 2. Furthermore, the artificial blood vessel VE has a third region R3 on one surface of the artificial blood vessel VE (in this embodiment, the outer surface (front surface) of the artificial blood vessel VE), which has a third region side first portion R31 (portion extending across multiple weft threads 2) where the warp thread 1 extends across multiple weft threads 2, and a third region side second portion R32 (portion extending across one weft thread 2) where the warp thread 1 extends across one weft thread 2. The first region R1, the second region R2, and the third region R3 are alternately formed in the extension direction D2 of the weft thread 2 as shown in FIG. 3. That is, the first region R1, the second region R2, and the third region R3 are repeatedly arranged in this order in the extension direction D2 of the weft thread 2. The second region first portion R21 is adjacent to the third region second portion R32 in the extending direction D2 of the weft 2, and the second region second portion R22 is adjacent to the third region first portion R31 in the extending direction D2 of the weft 2. When the artificial blood vessel VE of this embodiment has the above-mentioned configuration, as described later, the warp yarn 1 made of multifilament yarn that is extended long without being restrained in the second region first portion R21 or the third region first portion R31 spreads to the plain weave first region R1. Due to the three-dimensional structure of this warp yarn 1, when blood seeps out from the fiber gaps generated in the plain weave first region R1, the blood is prevented from leaking out and is retained within the three-dimensional structure. The blood is coagulated in the retained state, thereby improving the blood leakage resistance. The configuration and weaving structure of each part of the artificial blood vessel VE are described below.

[0024] The warp threads 1 are fibers that extend in one direction among the fibers that constitute the artificial blood vessel VE. In this embodiment, the warp threads 1 are fibers that extend along the length direction (axis X direction) of the artificial blood vessel VE. The warp threads 1 are made of a material that is applicable to a cloth artificial blood vessel that is made of a woven fiber structure. The material of the warp threads 1 is not particularly limited as long as it is applicable to a cloth artificial blood vessel. For example, the material of the warp threads 1 can be polyester, polytetrafluoroethylene, polyamide, etc. In addition, a composite material composed of two or more applicable materials having different properties such as melting point and stretch rate may be used as the material of the warp threads 1. For example, the material of the warp threads 1 can be a synthetic fiber in which polyethylene terephthalate (PET) and polytrimethylene terephthalate (PTT) are combined in the spinning stage to form one long fiber having a spiral crimp. For example, when a composite material having a spiral crimp and composed of two types of materials with different melting points and elasticity is used as the material for warp thread 1, the three-dimensional structure formed by warp thread 1 described below tends to expand in the extension direction D2 of weft thread 2, thereby improving the blood retention performance and improving blood leakage resistance.

[0025] In this embodiment, the warp threads 1 are made of multifilament yarns. The fineness of the warp threads 1 can be, for example, 0.25 to 2.50 dtex for the single yarn fineness of the warp threads 1, preferably 0.50 to 2.00 dtex, and 2 to 2500 dtex for the total yarn fineness of the warp threads 1, preferably 6 to 1600 dtex, more preferably 10 to 540 dtex, and even more preferably 30 to 200 dtex. By setting the single yarn fineness of the warp threads 1 and the total yarn fineness of the warp threads 1 within the above ranges, the warp threads 1 in the second region R2 and the third region R3 can be favorably spread toward the first region R1. Therefore, when blood seeps out from the gaps in the first region R1 by the warp threads 1 in the second region R2 and the third region R3, the blood is prevented from leaking out and is held by the three-dimensional structure of the warp threads 1, and the blood coagulates in the held state, thereby improving the blood leakage resistance. The "single yarn fineness" refers to the fineness of each filament constituting the warp yarn 1, and the "total fineness" refers to the product of the single yarn fineness and the number of filaments constituting the warp yarn 1. The number of filament yarns constituting each warp yarn (hereinafter referred to as the number of filaments) is not particularly limited, but for example, as described below, when the total number of filaments in the warp yarn 1 is 1.5 times or more the number of filaments in each weft yarn 2, and the number of warp yarns 1 straddling a plurality of weft yarns 2 in the second region R2 is one, the number of filaments in each warp yarn 1 can be 8 to 1000, preferably 12 to 800, more preferably 20 to 270, and even more preferably 60 to 100. As described below, when the number of filaments per warp thread 1 is 0.8 to 1.2 times the number of filaments per weft thread 2 and the number of warp threads 1 spanning multiple weft threads 2 in the second region R2 is two or more, the number of filaments per warp thread 1 can be 4 to 500, preferably 6 to 400, more preferably 10 to 135, and even more preferably 30 to 50.

[0026] The weft threads 2 are fibers that extend in a direction intersecting with the warp threads 1 among the fibers that constitute the artificial blood vessel VE. In this embodiment, the weft threads 2 are fibers that extend in the circumferential direction of the artificial blood vessel VE. The weft threads 2 are made of a material that is applicable to a cloth artificial blood vessel that is formed by a woven fiber structure. The material of the weft threads 2 is not particularly limited as long as it is a material that is applicable to a cloth artificial blood vessel. For example, the material of the weft threads 2 can be polyester, polytetrafluoroethylene, polyamide, etc.

[0027] Each of the weft yarns 2 may be a monofilament yarn or a multifilament yarn, but in this embodiment, the weft yarn 2 is made of a multifilament yarn. The fineness of the weft yarn 2 is not particularly limited, but for example, when the weft yarn 2 is a monofilament yarn, the single yarn fineness of the weft yarn can be 15 to 100 dtex, preferably 20 to 75 dtex. When each of the weft yarns 2 is made of a multifilament yarn, the single yarn fineness of the weft yarn 2 can be 0.25 to 2.50 dtex, preferably 0.50 to 2.00 dtex, and the total fineness of the weft yarn 2 can be 1 to 1250 dtex, preferably 3 to 800 dtex, more preferably 5 to 270 dtex, and even more preferably 15 to 100 dtex. The "single yarn fineness" is the fineness per filament (monofilament or multifilament) constituting the weft yarn 2, and the "total fineness" is the product of the single yarn fineness and the number of filaments constituting the weft yarn 2. When the weft yarn 2 is made of a multifilament yarn, the number of filament yarns constituting one weft yarn may be 4 to 500, preferably 6 to 400, more preferably 10 to 135, and further preferably 30 to 50.

[0028] The first region R1 is a part where the warp threads 1 and the weft threads 2 are plain woven. In FIG. 3, the first region R1 is a region where the warp threads 1a, 1b, 1e, 1f, 1i, and 1j intersect with the weft threads 2 (weft threads 2a to 2l). In the first region R1 of the plain weave structure, the warp threads 1 extend, as shown in FIG. 4, from one side of the artificial blood vessel VE (the outer surface (surface) of the artificial blood vessel VE; the upper surface in FIG. 4) to the other side (the inner surface of the artificial blood vessel VE; the lower surface in FIG. 4) so ​​as to cross only one weft thread 2 (without crossing multiple weft threads 2) from the other side to the one side. The first region R1 improves the strength of the artificial blood vessel VE, particularly the tensile strength (in the axial direction of the artificial blood vessel VE). The first region R1 extends along the extending direction D1 of the warp threads 1, and extends in the axial direction of the artificial blood vessel VE. A plurality of first regions R1 are arranged at predetermined intervals in the extension direction D2 of the weft yarn 2. A second region R2 and a third region R3 are arranged between one first region R1 and another first region R1 in the extension direction D2 of the weft yarn 2.

[0029] In this embodiment, as shown in FIG. 3, the first region R1 is formed by plain weaving two warp threads 1a, 1b (warp threads 1e, 1f or warp threads 1i, 1j) and multiple weft threads 2a-2l (and weft threads not shown). The number of warp threads 1 provided in one first region R1 can be 2 to 4, preferably 2 to 3, and more preferably 2. In this specification, when the warp thread 1 is a multifilament thread, the term "number of warp threads" refers not to the number of filaments constituting the multifilament thread, but to the number of warp threads 1 each consisting of multiple filament threads. By setting the number of warp threads 1 within the above-mentioned range, the area of ​​the first region R1 that is not covered by the warp threads 1 of the second region side first portion R21 and the warp threads 1 of the third region side first portion R31 can be reduced. Therefore, the plain weave first region R1 is easily covered three-dimensionally by the warp threads 1 of the second region first portion R21 and the warp threads 1 of the third region first portion R31, and when blood seeps out from the first region R1, the blood is held by the three-dimensional structure of the warp threads 1 of the second region first portion R21 and the warp threads 1 of the third region first portion R31, and the blood coagulates in the held state, thereby reducing the amount of blood leakage from the artificial blood vessel VE. In the artificial blood vessel VE, the ratio of the number of warp threads 1 in the first region R1 to the total number of warp threads 1 arranged in the extension direction D2 of the weft threads 2 in the first region R1 to the third region R3 (number of warp threads in the first region R1 / total number of warp threads) is not particularly limited, but may be, for example, 0.2 to 0.4 (1 / 3 in this embodiment). By setting the number of warp threads 1 and the ratio of the number of warp threads in the first region R1 within the above range, the strength of the artificial blood vessel VE can be increased while reducing the amount of blood leakage from the artificial blood vessel VE.

[0030] The second region R2 has a second region first portion R21 where the warp thread 1 crosses over a plurality of weft threads 2, and a second region second portion R22 where the warp thread 1 crosses over one weft thread 2. The second region first portion R21 and the second region second portion R22 are alternately provided in the extending direction D1 of the warp thread 1, as shown in FIG. 3. Since the second region R2 has the second region first portion R21 and the second region second portion R22, the artificial blood vessel VE can be made more flexible than an artificial blood vessel VE in which all of the artificial blood vessel VE has a plain weave structure. The portion of the warp thread 1c provided in the second region R2 may be made of one warp thread or may be made of multiple warp threads. The number of warp threads 1 provided in the second region R2 may be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0031] The second region side first portion R21 is a portion woven such that the warp threads 1 have a portion crossing a plurality of weft threads 2. In this embodiment, the warp threads 1c, 1g, 1k, etc. cross a plurality of weft threads 2. In the second region side first portion R21, the warp threads 1 cross a plurality of weft threads 2, so that the artificial blood vessel VE becomes more flexible in that portion than in the plain weave structure. In addition, when the warp threads 1 of the second region side first portion R21 are made of multifilament yarns, both ends of the second region side first portion R21 in the extension direction D1 of the warp threads 1 are bound by the weft threads 2 of the second region side second portion R22 (see portion P1 in FIG. 3). In this case, the second region side first portion R21 of the warp threads 1 made of multifilament yarns with both ends bound forms a three-dimensional structure in which the center portion in the extension direction D1 of the warp threads 1 extends in the extension direction D2 of the weft threads 2 (note that this three-dimensional structure also extends in the left-right direction and toward the front of the paper in FIG. 3). That is, in the warp yarn 1, the width of the central part in the extension direction D1 of the warp yarn 1 is larger than the width of the end part in the extension direction D1 of the warp yarn 1 (see FIG. 10). Therefore, the plain weave structured first region R1 adjacent to the second region side first portion R21 in the extension direction D2 of the weft yarn 2 is partially covered by the spread multifilament yarn of the second region side first portion R21. Due to this three-dimensional structure of the warp yarn 1, when blood seeps out from the fiber gaps generated in the plain weave woven first region R1, the seeped blood is held in the gaps between the filaments of the three-dimensional structure formed by the multifilaments. As a result, the blood coagulates in the held state, thereby improving the blood leakage resistance. In addition, in this embodiment, the third region side second portion R32 adjacent to the second region side first portion R21 in the extension direction D2 of the weft yarn 2 is also partially covered by the spread multifilament yarn of the second region side first portion R21. As a result, any gaps occurring in the third region side second portion R32 are also covered by the multifilament yarn of the second region side first portion R21, making it difficult for blood in the artificial blood vessel VE to leak to the outside.

[0032] In the second region side first portion R21 (from when the warp thread 1 emerges from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) to the other surface), the number of weft threads of the weft thread 2 that the warp thread 1 crosses over is not particularly limited, but may be, for example, 2 to 5, preferably 3 to 4, and more preferably 3 (as shown in FIG. 3). By setting the number of weft threads of the weft thread 2 that the warp thread 1 crosses over in the above-mentioned range in the second region side first portion R21, it is easy to spread the multifilament yarn of the warp thread 1 in the extending direction D2 of the weft thread 2, and the artificial blood vessel VE can be maintained at a predetermined strength.

[0033] The number of warp threads 1 constituting the second region side first portion R21 is not particularly limited as long as the warp threads 1 have a portion crossing over a plurality of weft threads 2. For example, the second region side first portion R21 (second region R2) may be composed of a plurality (two) warp threads (each of warp threads 1c, 1g, and 1k is composed of a plurality of warp threads). In addition, the second region side first portion R21 (second region R2) may have at least one warp thread 1 extending across (only) one weft thread 2 and at least one warp thread 1 crossing over a plurality of weft threads 2.

[0034] The second region side second portion R22 is a portion woven such that the warp thread 1 crosses only one weft thread 2 (the warp thread 1 does not cross multiple weft threads 2 from the time it exits from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) until it reaches the other surface). The second region side second portion R22 has a length approximately equal to the length of the second region side first portion R21 in the extending direction D1 of the warp thread 1. That is, the number of weft threads of the weft thread 2 in the second region side first portion R21 (three in FIG. 3) is equal to the number of weft threads of the weft thread 2 in the second region side second portion R22 (three in FIG. 3).

[0035] The third region R3 has a third region first portion R31 where the warp thread 1 crosses over a plurality of weft threads 2, and a third region second portion R32 where the warp thread 1 crosses over one weft thread 2. The third region first portion R31 and the third region second portion R32 are alternately provided in the extending direction D1 of the warp thread 1, as shown in FIG. 3. Since the third region R3 has the third region first portion R31 and the third region second portion R32, the artificial blood vessel VE can be made more flexible than an artificial blood vessel VE whose entire structure is a plain weave structure. The portion of the warp thread 1d provided in the third region R3 may be made of one warp thread or may be made of multiple warp threads. The number of warp threads 1 provided in the third region R3 may be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0036] The third region side first portion R31 is a portion woven such that the warp thread 1 has a portion crossing a plurality of weft threads 2. In this embodiment, the warp threads 1d, 1h, 1l, etc. cross a plurality of weft threads 2. In the third region side first portion R31, the warp threads 1 cross a plurality of weft threads 2, so that the artificial blood vessel VE becomes more flexible in that portion than in the plain weave structure. In addition, when the warp threads 1 of the third region side first portion R31 are made of multifilament yarns, both ends of the third region side first portion R31 in the extension direction D1 of the warp threads 1 are bound by the weft threads 2 of the third region side second portion R32 (see portion P2 in FIG. 3). In that case, the third region side first portion R31 of the warp threads 1 made of multifilament yarns with both ends bound forms a three-dimensional structure in which the center portion in the extension direction D1 of the warp threads 1 extends in the extension direction D2 of the weft threads 2. That is, in the warp yarn 1, the width of the central part in the extension direction D1 of the warp yarn 1 is larger than the width of the end part in the extension direction D1 of the warp yarn 1 (see FIG. 10). Therefore, the plain weave structured first region R1 adjacent to the third region side first portion R31 in the extension direction D2 of the weft yarn 2 is partially covered by the spread multifilament yarn of the third region side first portion R31. When blood seeps out from the fiber gaps generated in the plain weave woven first region R1 due to the three-dimensional structure of the warp yarn 1, the seeped blood is held in the gaps between the filaments of the three-dimensional structure formed by the multifilaments. As a result, the blood coagulates in the held state, improving the blood leakage resistance. In addition, in this embodiment, the second region side second portion R22 adjacent to the third region side first portion R31 in the extension direction D2 of the weft yarn 2 is also partially covered by the spread multifilament yarn of the third region side first portion R31. As a result, any gaps occurring in the second region-side second portion R22 are also covered by the multifilament yarn of the third region-side first portion R31, making it difficult for blood in the artificial blood vessel VE to leak to the outside.

[0037] In the third region side first portion R31 (from when the warp thread 1 emerges from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) to the other surface), the number of weft threads of the weft thread 2 that the warp thread 1 crosses over is not particularly limited, but may be, for example, 2 to 5, preferably 3 to 4, and more preferably 3 (as shown in FIG. 3). By setting the number of weft threads of the weft thread 2 that the warp thread 1 crosses over in the above-mentioned range in the third region side first portion R31, it is easy to spread the multifilament yarn of the warp thread 1 in the extending direction D2 of the weft thread 2, and the artificial blood vessel VE can be maintained at a predetermined strength.

[0038] The number of warp threads 1 constituting the third region side first portion R31 is not particularly limited as long as the warp threads 1 have a portion crossing over a plurality of weft threads 2. For example, the third region side first portion R31 (third region R3) may be composed of a plurality (two) warp threads (each of warp threads 1d, 1h, and 1l is composed of a plurality of warp threads). In addition, the third region side first portion R31 (third region R3) may have at least one warp thread 1 extending across (only) one weft thread 2 and at least one warp thread 1 crossing over a plurality of weft threads 2.

[0039] The third region side second portion R32 is a portion woven such that the warp thread 1 crosses only one weft thread 2 (the warp thread 1 does not cross multiple weft threads 2 from the time it exits from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) until it reaches the other surface). The third region side second portion R32 has a length approximately equal to that of the third region side first portion R31 in the extending direction D1 of the warp thread 1. That is, the number of weft threads of the weft thread 2 in the third region side first portion R31 (three in FIG. 3) is the same as the number of weft threads of the weft thread 2 in the third region side second portion R32 (three in FIG. 3).

[0040] As shown in Figures 5 and 6A to 6C, the artificial blood vessel VE of this embodiment has a plurality of covered portions C that are provided at multiple locations on the surface of the artificial blood vessel VE, each of which covers the multifilament yarn in a planar manner, and uncovered portions UC that are provided between the multiple covered portions C on the surface of the artificial blood vessel VE and are not covered by the covered portions C.

[0041] The covering portion C partially covers the filament yarns of the multifilament yarns constituting one warp yarn or one weft yarn on the surface of the artificial blood vessel VE. "Coating the multifilament yarns in a planar manner" means that the covering portion C extends on the surface of the artificial blood vessel VE in the extending direction of the multifilament yarns (extending direction D1 of warp yarn 1) and in a direction perpendicular to the extending direction of the multifilament yarns (extending direction D2 of weft yarn 2) so as to close the gaps on the surface side of the artificial blood vessel VE between the adjacent filament yarns constituting the multifilament yarn. As will be described in detail later, the covering portion C is provided so that the gaps between the filament yarns located inside the covering portion C in the radial direction of the artificial blood vessel VE are closed on the surface of the artificial blood vessel VE. This improves the blood leakage resistance of the artificial blood vessel VE.

[0042] As shown in Fig. 5 and Figs. 6A to 6C, the covered portions C are provided at a plurality of locations on the surface of the artificial blood vessel VE. Here, "a plurality of locations" means that the covered portions C are provided at a plurality of locations when the entire surface of the artificial blood vessel VE is divided into a plurality of portions. The covered portions C may be provided separately from one another and scattered at a plurality of locations (see Fig. 6A), or may be provided continuously at a plurality of locations in the axial direction (extension direction D1 of the warp threads 1) and / or circumferential direction (extension direction D2 of the weft threads 2) of the artificial blood vessel VE (non-covered portions UC are scattered; see Fig. 6C). Note that the covered portions C are not regularly distributed and may have some locations where they are locally concentrated and some locations where they are not concentrated.

[0043] As shown in Figs. 6A to 6C, the uncovered portions UC are the remaining portions of the covered portions C that are not covered by the covered portions C on the surface of the artificial blood vessel VE. As shown in Figs. 6A to 6C, the uncovered portions UC are arranged between the covered portions C provided at a plurality of locations. The uncovered portions UC are arranged between the covered portions C, for example, in the axial direction (extension direction D1 of the warp threads 1) and / or the circumferential direction (extension direction D2 of the weft threads 2) of the artificial blood vessel VE. As will be described in detail later, the uncovered portions UC are arranged between the covered portions C on the surface of the artificial blood vessel VE, thereby contributing to maintaining the flexibility of the artificial blood vessel VE. In this embodiment, the multifilament yarns of the warp threads 1 and the weft threads 2 in the region of the uncovered portions UC are exposed on the surface of the artificial blood vessel VE with the gaps between the adjacent filament yarns maintained (see Figs. 6A and 6B).

[0044] As described above, in this embodiment, the artificial blood vessel VE has a plurality of covered portions C provided at a plurality of locations on the surface of the artificial blood vessel VE, each of which covers a plurality of multifilament yarns in a planar manner, and uncovered portions UC provided on the surface of the artificial blood vessel VE between the plurality of covered portions C and which are not covered by the covered portions C. In this case, as will be described later, the visible light transmittance can be reduced by the covered portions C, and for example, it becomes easy to set the visible light transmittance of the artificial blood vessel VE to a range of 1.5 to 4%, making it easy to achieve both flexibility and blood leakage resistance of the artificial blood vessel VE.

[0045] In this embodiment, as shown in FIG. 5, the artificial blood vessel VE has an inner woven portion IW in which a plurality of filament yarns of a multifilament yarn extend in a state in which they are separated from each other on the radially inner side of the artificial blood vessel VE (lower side in FIG. 5) with respect to the covering portion C. The inner woven portion IW constitutes a part of the woven structure of the artificial blood vessel VE, and is covered by the covering portion C in a state in which a plurality of filament yarns are separated from each other with a gap therebetween. The plurality of filament yarns of the inner woven portion IW are shown in FIG. 5 as a schematic, but extend in a bundle shape in which a plurality of adjacent yarns are adjacent in the radial direction of the artificial blood vessel VE (up and down direction in FIG. 5) and a plurality of adjacent yarns are adjacent in the extension direction D2 of the weft yarn 2 (depth direction of the paper in FIG. 5). Note that the inner woven portion IW is covered by the covering portion C and is not visible in FIG. 6A and FIG. 6C, but is located in the depth direction of the paper with respect to the covering portion C. The structure of the inner woven portion IW is not particularly limited as long as a plurality of filament yarns extend in a state in which they are separated from each other on the radially inner side of the artificial blood vessel VE with respect to the covering portion C. In this embodiment, the inner woven portion IW has a structure in which the multifilament yarns in the region corresponding to the second region side first portion R21 (and the third region side first portion R31) are spread in the extension direction D2 of the weft yarn 2, and the multiple filament yarns constituting the multifilament yarns of the inner woven portion IW extend in a mutually scattered state along the extension direction D1 of the warp yarn 1. Note that in this embodiment, as shown in Fig. 5, the warp yarns 1 have a two-layer structure in the region corresponding to the second region side first portion R21 (and the third region side first portion R31) of a covering portion C which is a planar resin layer on the surface side of the artificial blood vessel VE, and an inner woven portion IW which is a multifilament layer located radially inward from the covering layer C.

[0046] By providing the inner woven portion IW on the radially inner side of the covering portion C, a plurality of filament yarns extend in a separated state with gaps between each other on the radially inner side of the planar covering portion C. Therefore, the inner woven portion IW made of multifilament yarns covered by the covering portion C extends while maintaining a predetermined flexibility. Therefore, even if the planar covering portion C is provided, the flexibility of the artificial blood vessel VE as a whole is unlikely to be impaired, and it is possible to achieve both flexibility and blood leakage resistance of the artificial blood vessel VE. Furthermore, by having the inner woven portion IW, the artificial blood vessel inner structure can maintain a woven structure and suppress impairment of cell invasion.

[0047] In addition, it is preferable that the covered portions C and the uncovered portions UC are alternately provided in the axial direction (extension direction D1 of the warp threads 1) and / or circumferential direction (extension direction D2 of the weft threads 2) of the artificial blood vessel VE on a part of the surface of the artificial blood vessel VE. In this case, the covered portions C and the uncovered portions UC are arranged in a balanced manner in the axial direction and / or circumferential direction of the artificial blood vessel VE. Therefore, the flexibility and blood leakage resistance of the artificial blood vessel VE are improved in a balanced manner, and the artificial blood vessel VE is prevented from becoming locally hard or from becoming locally susceptible to blood leakage. In particular, when the covered portions C and the uncovered portions UC are alternately provided in the axial direction of the artificial blood vessel VE, the artificial blood vessel VE becomes easier to bend, and the artificial blood vessel VE is easier to place in the body. In addition, when the covered portions C and the uncovered portions UC are alternately provided in the circumferential direction of the artificial blood vessel VE, the artificial blood vessel VE becomes easier to twist, and deformation (crushing) when the artificial blood vessel VE is twisted is suppressed. Therefore, even if the artificial blood vessel VE is subjected to a twisting force, for example, by screwing when connected to an artificial heart-lung machine, the artificial blood vessel VE is prevented from being crushed by twisting. Therefore, adverse effects caused by twisting of the artificial blood vessel VE, such as blood coagulating at the crushed portion and blocking the artificial blood vessel VE, are prevented. In this embodiment, the artificial blood vessel VE has the covered portions C and the uncovered portions UC alternately provided in both the axial direction and the circumferential direction of the artificial blood vessel VE. In this case, the flexibility and leakage resistance of the artificial blood vessel VE are improved in a well-balanced manner throughout the artificial blood vessel VE.

[0048] The region where the covering portion C is provided is not particularly limited as long as the covering portion C is provided at a plurality of locations on the surface of the artificial blood vessel VE with a predetermined area. In this embodiment, the covering portion C is provided at the portions R21 and R31 of the warp thread 1 that extend across a plurality of weft threads 2 as shown in Figs. 5 and 7 (only the portion R21 that extends across a plurality of weft threads 2 is shown in Figs. 5 and 7). More specifically, the covering portion C is provided at the portions corresponding to the second region side first portion R21 and the third region side first portion R31. Note that the covering portion C does not necessarily need to cover all of the plurality of filament threads provided at the portions that extend across a plurality of weft threads 2 (the second region side first portion R21 and the third region side first portion R31), but it is sufficient that the covering portion C covers most of the plurality of filament threads (for example, but not limited to, 50% or more, preferably 80% or more).

[0049] The structure of the covering part C is not particularly limited as long as it can cover the multifilament yarn in a planar manner. In this embodiment, the covering part C is configured by a resin layer coated on the surface of the multifilament yarn or a state in which the multifilament yarn is melted and solidified. The "state in which the multifilament yarn is melted and solidified" refers to a state in which a part of the multifilament yarn constituting the warp yarn 1 and / or the weft yarn 2 is melted once by heating or the like and then solidified to form a planar resin layer. In this case, the surface of the artificial blood vessel VE is covered with the planar covering part C, which is a melted and solidified resin layer. The "resin layer coated on the surface" refers to a resin layer formed by coating the multifilament yarn constituting the warp yarn 1 and / or the weft yarn 2 with a resin material in a planar manner.

[0050] In this embodiment, the artificial blood vessel VE may be configured to have the above-mentioned first region R1, second region R2, and third region R3, and to have a visible light transmittance of 1.5 to 4%. In this case, as described later, it is possible to achieve a high level of both flexibility and blood leakage resistance of the artificial blood vessel VE. By setting the lower limit of the visible light transmittance of the artificial blood vessel VE to 1.5%, more preferably 2%, the flexibility of the artificial blood vessel VE can be increased. Furthermore, by setting the upper limit of the visible light transmittance of the artificial blood vessel VE to 4%, more preferably 3%, the blood leakage resistance of the artificial blood vessel VE can be increased.

[0051] Here, the "visible light transmittance" of the artificial blood vessel VE is the ratio of light transmitted from one surface (inner surface) of the artificial blood vessel VE to the other surface (outer surface) when the artificial blood vessel VE is irradiated with visible light in the wavelength range of 380 to 780 nm (see FIG. 10). As a calculation method, the maximum light (255) is set as the portion through which light is transmitted with respect to the image data when the surface of the artificial blood vessel VE is photographed by a digital microscope with maximum light (e.g., 255 in the case of 256 gradations), and the ratio of the number of pixels with maximum light to the total number of pixels is calculated as the light transmittance. The visible light transmittance is the visible light transmittance of the artificial blood vessel VE in a predetermined region (e.g., a region including 10 warp threads 1 and 10 weft threads 2) having a predetermined area or more including the peaks M and valleys V, and for example, the visible light transmittance in the predetermined region can be calculated at a plurality of points and the average value thereof can be calculated. The visible light transmittance of the artificial blood vessel VE is not limited to the above-mentioned range. Furthermore, when the visible light transmittance of the artificial blood vessel VE is within the above-mentioned range, even if the visible light transmittance is locally outside the range of 1.5 to 4% in a part of the artificial blood vessel VE, it is sufficient as long as the average value of the transmittance is within the range. The visible light transmittance can be measured, for example, by cutting a part of the artificial blood vessel VE as a sample and using a commercially available spectrophotometer. The method for measuring the visible light transmittance is not particularly limited, but for example, the sample of the artificial blood vessel VE to be measured is moved while measuring the spectral transmittance at multiple points (for example, 10 points), and the visible light transmittance can be calculated as the arithmetic average of the multiple measured values.

[0052] The visible light transmittance corresponds to the size of the gaps that occur in the intersection regions of the warp threads 1 and weft threads 2 in the weave structure of the artificial blood vessel VE. Normally, if the weave structure has a visible light transmittance in the above-mentioned range of 1.5 to 4%, the artificial blood vessel will have a dense weave structure and will become hard. On the other hand, in this embodiment, if the specific weave structure having the above-mentioned first region R1, second region R2, and third region R3 is used and the visible light transmittance is 1.5 to 4%, it is possible to achieve a high level of both flexibility and blood leakage resistance of the artificial blood vessel VE, as will be described later.

[0053] In this embodiment, as shown in FIG. 7, the covering portion C spreads in the extending direction D2 of the weft yarn 2 so as to cover at least a part of the surface of the warp yarn 1 arranged between a pair of the second region side first parts R21 in the extending direction D2 of the weft yarn 2. In this embodiment, the covering portion C is configured to cover at least a part of the other warp yarns 1d, 1e, 1f different from the one warp yarn 1c including the second region side first part R21 in which the covering portion C is provided. More specifically, the covering portion C is configured to cover at least a part of the warp yarns 1d, 1e, 1f in the first region R1 or the second region side second part R22. In addition, although not shown in FIG. 7, the covering portion C spreads in the extending direction D2 of the weft yarn 2 so as to cover at least a part of the surface of the warp yarn 1 arranged between a pair of the third region side first parts R31 in the extending direction D2 of the weft yarn 2. In this embodiment, the covering portion C is configured to cover at least a part of a warp thread other than one warp thread including the third region side first portion R31 in which the covering portion C is provided. More specifically, the covering portion C is configured to cover at least a part of a warp thread of the first region R1 or the third region side second portion R32.

[0054] In this case, as shown in FIG. 7, the covering portion C of one of the warp threads 1c, 1g covers the other warp threads adjacent in the extending direction D2 of the weft thread 2 (for example, warp threads 1d, 1e, 1f in the case of FIG. 7). This suppresses not only blood leakage from the gaps between the multifilament threads of one warp thread 1, but also blood leakage from the gaps between the multifilament threads of the other warp threads 1 different from the one warp thread 1. Therefore, the blood leakage resistance of the artificial blood vessel VE is improved. In addition, the covering portion C is provided on the surface of one of the warp threads 1 that is on the radially outer side of the artificial blood vessel VE, and the multifilament threads are in a loose state in the radially inner part. Therefore, the one warp thread 1 provided with the covering portion C and the other warp threads 1 are prevented from being fixed to each other by facing each other in the radial direction of the artificial blood vessel VE with the loose multifilament threads (note that there may be cases where some parts are partially fixed to each other due to individual differences, temperature conditions, etc.). Therefore, the covering portion C can move in the radial direction of the artificial blood vessel VE relative to the surface of the warp yarn 1 arranged between a pair of the second region side first parts R21 in the extension direction D2 of the weft yarn 2 and the surface of the warp yarn 1 arranged between a pair of the third region side first parts R31 in the extension direction D2 of the weft yarn 2 in response to the movement of the artificial blood vessel VE. Specifically, as shown in FIG. 8, the covering portion C is formed on the surface of one warp yarn 1, and the multifilament yarns in a loose state come into contact with the surfaces of the other warp yarns 1. In this state, for example, when the artificial blood vessel VE is placed in the body, a force may be applied radially outward relative to the inside of the artificial blood vessel VE due to pulsation of the blood flow, etc. In this case, the artificial blood vessel VE is deformed so that the diameter increases. In this embodiment, one warp yarn 1 and the other warp yarns 1 are not fixed to each other, so that one warp yarn 1 can move relative to the other warp yarns 1 in the radial direction of the artificial blood vessel VE and in the extension direction D2 of the weft yarn 2. Therefore, for example, when the artificial blood vessel VE expands, blood leakage is suppressed by the covering portion C, and the artificial blood vessel VE can flexibly deform in accordance with the blood flow through the artificial blood vessel VE by moving one warp thread 1 relative to the other warp threads 1. This allows the artificial blood vessel VE to have both resistance to blood leakage and flexibility.

[0055] In this embodiment, as shown in Fig. 2 and Fig. 6A, the artificial blood vessel is configured such that peaks M and valleys V are alternately formed in the axial direction X, and the visible light transmittance of the valleys V is lower than that of the peaks M. In this case, the valleys V have low transmittance and high blood leakage resistance, but are hard. However, the peaks M are more flexible than the valleys V, so that the artificial blood vessel VE as a whole is flexible. In addition, since the artificial blood vessel VE has the above-mentioned transmittance, the artificial blood vessel VE as a whole is ensured to have blood leakage resistance, while the valleys V have low transmittance (small gaps) and high strength. Therefore, when a medical instrument such as a guide wire or a catheter is inserted inside the artificial blood vessel VE, the strength of the valleys V that come into contact with the medical instrument is high, so that damage to the artificial blood vessel VE due to contact with the medical instrument or the like can be suppressed. The visible light transmittance of the peaks M and valleys V is not limited, but may be, for example, 1 to 3% in the valleys V and 2 to 4.5% in the peaks M. The visible light transmittance of the valleys V and the visible light transmittance of the peaks M may be approximately the same.

[0056] An example of a method for producing the artificial blood vessel VE of this embodiment will be described below. However, the following description is merely an example, and the artificial blood vessel VE of the present invention is not limited to the following method.

[0057] First, a base material for the artificial blood vessel VE having the above-mentioned woven structure is prepared. Specifically, as shown in Fig. 3, the base material includes a first region R1 in which warp yarns 1 and weft yarns 2 are woven in a plain weave, a second region R2 having a second region-side first portion R21 and a second region-side second portion R22, and a third region R3 having a third region-side first portion R31 and a third region-side second portion R32. At this point, the base material is not cylindrical but sheet-like.

[0058] Next, the covering portion C is formed on the base material. Specifically, a heating medium (not shown) is brought into contact with the surface of the base material that will become the outer surface (surface) of the artificial blood vessel VE, a part of the base material (a part of the multifilament yarn) is melted, and the melted part is cooled and solidified. In the above-mentioned base material, the second region side first portion R21 and the third region side first portion R31 protrude toward the outer surface side of the artificial blood vessel VE in the thickness direction of the base material more than other portions (for example, the first region R1, the second region side second portion R22, and the third region side second portion R32). Therefore, the multifilament yarn on the surface of the second region side first portion R21 and the third region side first portion R31 melts first. By adjusting the temperature of the heating medium, the heating time, etc., it becomes possible to melt only the surface of the base material. Specifically, in the thickness direction of the base material, only the surface layer portion of the multifilament yarn of the second region side first portion R21 and the third region side first portion R31 that will be the outer surface side of the artificial blood vessel VE is melted, and the portion that will be the inner surface side of the artificial blood vessel VE is not melted. As a result, a covering portion C is formed that covers the multifilament yarns of the second region side first portion R21 and the third region side first portion R31 in a planar manner. In this case, the multifilament yarns of the base material remain in a state in which multiple filament yarns are loosened in the portion on the inner surface side of the artificial blood vessel VE. As a result, a base material having a two-layer structure of the covering portion C and the inner woven portion IW is obtained. Since the inner side (inner woven portion IW) of the multifilament yarns of the second region side first portion R21 and the third region side first portion R31 is not melted, as shown in FIG. 7, when the covering portion C of the warp yarns 1c, 1g covers the surface of the warp yarns 1d, 1e, 1f arranged between the second region side first portions R21, R21 of the pair of warp yarns 1c, 1g, the covering portion C (inner woven portion IW) is not fixed to the covered warp yarns 1d, 1e, 1f. 8 and 9, the covering portion C can move relative to the warp threads 1 covered by the covering portion C in the radial direction of the artificial blood vessel VE and in the extension direction D2 of the weft threads 2 in response to the movement of the artificial blood vessel VE (for example, the movement of the artificial blood vessel VE when it expands radially outward). Thus, in this embodiment, even if the artificial blood vessel VE moves, one warp thread 1 provided with the covering portion C and another warp thread 1 covered by the covering portion C can move relative to each other and flexibly deform while maintaining a high blood leakage resistance.Therefore, the artificial blood vessel VE of this embodiment can improve the blood leakage resistance while maintaining flexibility. Instead of melting the substrate, a resin layer may be coated on the multifilament yarn on the surface of the substrate. When coating the surface of the multifilament yarn with a resin layer, instead of the above-mentioned substrate heating process (process of melting a part of the multifilament yarn), a resin material can be applied to the surface of the multifilament yarn in a desired pattern by a known method to form the covering portion C.

[0059] Next, the base material is processed into a cylindrical shape to form a cylindrical body CY (see FIG. 11). At this point, the peaks M and valleys V have not yet been formed in this cylindrical body CY. A known method for manufacturing a cylindrical artificial blood vessel having a predetermined woven structure (an artificial blood vessel having no pleats) can be used as a method for forming the cylindrical body CY, and therefore a detailed description thereof will be omitted. The step of forming the cylindrical body CY may be performed before the step of contacting the base material with a heating medium described above.

[0060] After the base material is processed into a cylindrical shape to form a cylindrical body CY, as shown in FIG. 11, peaks M and valleys V are formed in the cylindrical body CY. Specifically, the cylindrical body CY is placed on the outside of a molding core 3 (see FIG. 11) having protrusions 31 and recesses 32 corresponding to the peaks M and valleys V. The molding core 3 has a size and shape corresponding to an artificial blood vessel VE having peaks M and valleys V of a desired size and shape. In this embodiment, the molding core 3 is configured so that the cylindrical body CY can be covered on its outside. The outer diameter of the protrusions 31 of the molding core 3 is preferably the same as or smaller than the inner diameter of the cylindrical body CY, but the outer diameter of the protrusions 31 may be slightly larger than the inner diameter of the cylindrical body CY. In this embodiment, the molding core 3 is supported rotatably around an axis X by a support (not shown) of a molding device including the molding core 3.

[0061] When the tubular body CY is disposed outside the core material 3, as shown in FIG. 11, the winding member 4 is wound around a part of the circumferential direction of the tubular body CY along the recessed portion 32 of the core material 3 while the tubular body CY is disposed outside the core material 3. The winding member 4 is a member for pressing a part of the tubular body CY disposed outside the core material 3 against the recessed portion 32 of the core material 3 to form a part corresponding to the valley portion V in the tubular body CY. The winding member 4 is not particularly limited as long as it can form the valley portion V in the tubular body CY. In this embodiment, the winding member 4 can be a wire having a size that can enter between a pair of protruding portions 31 corresponding to a pair of peak portions M. In this embodiment, the winding member 4 is stretched in a tensioned state (see FIG. 12), and the core material 3 is rotated around the axis X, whereby the winding member 4 is wound spirally around the outer periphery of the tubular body CY, forming the valley portion V in the tubular body CY. Alternatively, the valleys V may be formed in the tubular body CY by moving the winding member 4 so as to wind helically around the forming core 3 without rotating the forming core 3.

[0062] Next, the cylindrical body CY is pressed inward in the radial direction in a point-like manner. Specifically, the cylindrical body CY, which is disposed outside the molding core 3 and has the winding member 4 wound around it, is stored in the storage member 5 (see Figs. 13 and 14). The storage member 5 has a compression element PR (indicated by a dot in Fig. 14) disposed between the inner surface of the storage member 5 and the outside of the cylindrical body CY. In this embodiment, the compression element PR presses the cylindrical body CY inward in the radial direction. In this embodiment, the compression element PR is composed of a plurality of granular bodies. In this embodiment, since the compression element PR is composed of a plurality of granular bodies, the granular compression element PR comes into contact with the warp threads 1 and weft threads 2 of the cylindrical body CY in a point-like manner. In this case, a force is applied more evenly to the warp threads 1 and weft threads 2 than in a wire-shaped compression element (for example, a wire-shaped compression element that is wound around the entire cylindrical body CY along the extension direction of the peaks M (the circumferential direction of the artificial blood vessel VE)) that comes into linear contact with the cylindrical body CY. Therefore, when the compression element PR compresses the tubular body CY, a large force is applied locally, causing the warp threads 1 and the weft threads 2 to shift in position, thereby preventing the gap from becoming large locally.

[0063] In this embodiment, as shown in FIG. 14, in a state where the cylindrical body CY, in which the molding core 3 and the winding member 4 are wound, is housed in the housing member 5, a plurality of granular compression elements PR are filled in the clearance between the cylindrical body CY and the inner surface of the housing member 5. In this embodiment, the housing member 5 is configured so that the internal volume of the housing member 5 can be reduced, and as the internal volume is reduced, the compression elements PR press the cylindrical body CY radially inward. As a result, a force is applied radially inward to the second region side first portion R21 and the third region side first portion R31 of the warp thread 1, which is made of multifilament yarn. Therefore, the second region side first portion R21 and the third region side first portion R31 are pressed by the compression elements PR and come into close contact with the shape of the surface of the warp thread 1, which is arranged radially inward of the artificial blood vessel VE with respect to the covering portion C. This further improves the blood leakage resistance of the artificial blood vessel VE.

[0064] The material and size of the compression element PR are not particularly limited as long as it is configured to be able to press the cylindrical body CY radially inward. The compression element PR may be configured, for example, from a metallic material that has a predetermined rigidity and is capable of conducting heat.

[0065] The configuration of the storage member 5 is not particularly limited as long as the tubular body CY can be pressed radially inward by the granular compression elements PR. In this embodiment, the storage member 5 includes a cylindrical body 51 and a lid portion 52 configured to be screwed to an end of the body 51, as shown in FIG. 13. By screwing the lid portion 52 to the body 51, the lid portion 52 moves in the axial direction of the body 51 relative to the body 51. When the lid portion 52 moves in the axial direction of the body 51, the pressing body 53 is pressed in the axial direction of the body 51 by the lid portion 52, and the internal volume of the body 51 becomes smaller. As a result, the granular compression elements PR stored in the storage member 5 are pressed, and the tubular body CY is pressed radially inward by the compression elements PR. The storage member may have another configuration. For example, the tubular body CY may be pressed by a pressing member such as a weight instead of the lid portion 52 of the storage member. Specifically, with a granular compression element PR arranged around a cylindrical body CY within a accommodating member, a load may be applied to the compression element PR from outside the accommodating member by a pressure member such as a weight, thereby pressing the cylindrical body CY radially inward.

[0066] Next, the compression element PR is heated in a state where the tubular body CY is compressed by the compression element PR in the housing member 5 (see FIG. 14). In this embodiment, the housing member 5 is placed in a heating furnace and heated, so that the compression element PR is heated via the housing member 5. As a result, the tubular body CY is heated by heat transfer from the compression element PR. The tubular body CY is heated in a state where the parts in contact with the compression element PR (particularly the parts of the first part R21 on the second region side and the first part R31 on the third region side) are pressed in a spot-like manner, so that the tubular body CY is deformed so as to closely fit along the surface shape of the warp yarn 1 covered by the covering part C. Thereafter, the tubular body CY taken out of the housing member 5 is held in the shape in the spot-like pressurized state, and the artificial blood vessel VE is completed. In this embodiment, the tubular body CY is pressed in a spot-like manner, so that the covering part C has a recess that is recessed on the radially inner side of the artificial blood vessel VE (see FIG. 6B). As described above, the recesses reduce the gap between the warp threads 1 covered by the covering C, and the multiple recesses also make the artificial blood vessel VE more flexible and easier to bend. The temperature in the heating step is not particularly limited, and the artificial blood vessel VE may be heated to a temperature that can deform the covering C.

[0067] Incidentally, instead of placing the containing member 5 in a heating furnace, the compression element PR may be made of a conductive material, and an electric current may be passed through the compression element PR to heat it, thereby heating the cylindrical body CY.

[0068] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Note that the above embodiment mainly describes the invention having the following configuration.

[0069] (1) An artificial blood vessel having weft yarns and warp yarns made of multifilament yarns, The artificial blood vessel comprises: A first region in which the warp yarns and the weft yarns are woven in a plain weave; a second region on one surface of the artificial blood vessel, the second region having a first portion on a second region side where the warp threads cross a plurality of weft threads and a second portion on the second region side where the warp threads extend across one weft thread; a third region on one surface of the artificial blood vessel, the third region having a first portion on a third region side where the warp threads cross a plurality of weft threads and a second portion on the third region side where the warp threads extend across one weft thread; are alternately arranged in the extending direction of the weft yarn, the second region side first portion is adjacent to the third region side second portion in the extension direction of the weft, and the second region side second portion is adjacent to the third region side first portion in the extension direction of the weft, the second region side first portion and the third region side first portion have a covering portion constituted by a state in which the multifilament yarn on the surface of the second region side first portion and the third region side first portion is melted and solidified, or a resin layer coated on the surface of the multifilament yarn, the covering portion covering the multifilament yarn of the second region side first portion and the third region side first portion in a planar manner, the covering portion extends in the extending direction of the weft yarn so as to cover at least a part of a surface of the warp yarn arranged between the pair of the second region side first portions in the extending direction of the weft yarn and a part of a surface of the warp yarn arranged between the pair of the third region side first portions in the extending direction of the weft yarn, The covering portion is configured to be movable in the radial direction of the artificial blood vessel relative to a surface of a warp yarn disposed between a pair of first portions on the second region side in the extending direction of the weft yarn and a surface of a warp yarn disposed between a pair of first portions on the third region side in the extending direction of the weft yarn in response to a movement of the artificial blood vessel. Artificial blood vessel.

[0070] (2) The artificial blood vessel described in (1), having an inner woven portion in which the multiple filament yarns of the multifilament yarn extend separately from one another, radially inward of the artificial blood vessel relative to the covering portion.

[0071] (3) The artificial blood vessel according to (1) or (2), wherein the covering portion has a recess that is concave on the radially inner side of the artificial blood vessel.

[0072] (4) A method for producing an artificial blood vessel having a weft yarn and a warp yarn composed of a multifilament yarn, the method comprising the steps of: A first region in which the warp yarns and the weft yarns are woven in a plain weave; a second region on one surface of the artificial blood vessel, the second region having a first portion on a second region side where the warp threads cross a plurality of weft threads and a second portion on the second region side where the warp threads extend across one weft thread; a third region on one surface of the artificial blood vessel, the third region having a first portion on a third region side where the warp threads cross a plurality of weft threads and a second portion on the third region side where the warp threads extend across one weft thread; A step of preparing a base material having the above-mentioned alternately in the extension direction of the weft yarn; a step of contacting a surface of the base material that will become the outer surface of the artificial blood vessel with a heating medium to melt and solidify the multifilament yarns on the surfaces of the second region side first portion and the third region side first portion, or by coating the surfaces of the second region side first portion and the third region side first portion with a resin layer to form a covering portion that covers the multifilament yarns on the second region side first portion and the third region side first portion in a planar manner; A step of forming a cylindrical body by processing the base material into a cylindrical shape; a step of housing the cylindrical body in a housing member having a compression element, and compressing the cylindrical body radially inward in a point-like manner by the compression element disposed between an inner surface of the housing member and an outside of the cylindrical body; a step of heating the compression element while the cylindrical body is pressed in a radially inward manner in a point-like manner, thereby deforming the surface of the covering portion into a shape in a pressurized state; Equipped with the covering portion extends in the extending direction of the weft yarn so as to cover at least a part of a surface of the warp yarn arranged between the pair of the second region side first portions in the extending direction of the weft yarn and a part of a surface of the warp yarn arranged between the pair of the third region side first portions in the extending direction of the weft yarn, The covering portion is configured to be movable in the radial direction of the artificial blood vessel relative to a surface of a warp yarn disposed between a pair of first portions on the second region side in the extending direction of the weft yarn and a surface of a warp yarn disposed between a pair of first portions on the third region side in the extending direction of the weft yarn in response to a movement of the artificial blood vessel. method. [Explanation of symbols]

[0073] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 1k, 1l warp 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j, 2k, 2l weft 3 Core material for molding 31 Convex 32 Recess 4. Winding material 5. Storage material 51 Main unit 52 Lid 53 Pressing body C Covering part CY Cylindrical body D1: Extension direction of warp threads (axial direction of artificial blood vessel) D2 Extension direction of weft thread (circumferential direction of artificial blood vessel) IW Inner Oribe M Yamabe The summit of Mt. P1: The weft thread portion that binds both ends of the first part on the second region side P2: Weft thread portion binding both ends of the first part on the third region side PL, PL1, PL2 flat surface PR compression factor R1 1st area R2 2nd area R21: First portion on the second region side (portion extending across multiple wefts) R22: Second region side, second part (part extending across one weft yarn) R3 3rd area R31: Third region side first portion (portion extending across multiple wefts) R32 2nd part on the 3rd region side (part extending across one weft thread) UC Uncoated part V Tanibe Vb Bottom of valley VE Artificial Blood Vessel X Axis of artificial blood vessel θ Angle between the flat surface on one side and the flat surface on the other side

Claims

1. An artificial blood vessel having a weft and a warp composed of multifilament yarns, The artificial blood vessel comprises: A first region in which the warp yarns and the weft yarns are woven in a plain weave; a second region on one surface of the artificial blood vessel, the second region having a first portion on a second region side where the warp threads cross a plurality of weft threads and a second portion on the second region side where the warp threads extend across one weft thread; a third region on one surface of the artificial blood vessel, the third region having a first portion on a third region side where the warp threads cross a plurality of weft threads and a second portion on the third region side where the warp threads extend across one weft thread; are alternately arranged in the extending direction of the weft yarn, the second region side first portion is adjacent to the third region side second portion in the extension direction of the weft, and the second region side second portion is adjacent to the third region side first portion in the extension direction of the weft, the second region side first portion and the third region side first portion have a covering portion constituted by a state in which the multifilament yarn on the surface of the second region side first portion and the third region side first portion is melted and solidified, or a resin layer coated on the surface of the multifilament yarn, the covering portion covering the multifilament yarn of the second region side first portion and the third region side first portion in a planar manner, the covering portion extends in the extending direction of the weft yarn so as to cover at least a part of a surface of the warp yarn disposed between the pair of the second region side first portions in the extending direction of the weft yarn and a part of a surface of the warp yarn disposed between the pair of the third region side first portions in the extending direction of the weft yarn, The covering portion is configured to be movable in a radial direction of the artificial blood vessel relative to a surface of a warp yarn disposed between a pair of first portions on the second region side in the extending direction of the weft yarn and a surface of a warp yarn disposed between a pair of first portions on the third region side in the extending direction of the weft yarn in response to a movement of the artificial blood vessel. Artificial blood vessels.

2. The artificial blood vessel according to claim 1, further comprising an inner woven portion in which the filament yarns of the multifilament yarn extend in a separated state from each other, the inner woven portion being radially inward of the artificial blood vessel relative to the covering portion.

3. The artificial blood vessel according to claim 1 , wherein the covering portion has a recessed portion that is recessed radially inward of the artificial blood vessel.

4. 1. A method for producing an artificial blood vessel having a weft yarn and a warp yarn composed of a multifilament yarn, the method comprising the steps of: A first region in which the warp yarns and the weft yarns are woven in a plain weave; a second region on one surface of the artificial blood vessel, the second region having a first portion on a second region side where the warp threads cross a plurality of weft threads and a second portion on the second region side where the warp threads extend across one weft thread; a third region on one surface of the artificial blood vessel, the third region having a first portion on a third region side where the warp threads cross a plurality of weft threads and a second portion on the third region side where the warp threads extend across one weft thread; A step of preparing a base material having the above-mentioned alternately in the extension direction of the weft yarn; a step of contacting a surface of the base material that will become the outer surface of the artificial blood vessel with a heating medium to melt and solidify the multifilament yarns on the surfaces of the second region side first portion and the third region side first portion, or by coating the surfaces of the second region side first portion and the third region side first portion with a resin layer to form a covering portion that covers the multifilament yarns on the second region side first portion and the third region side first portion in a planar manner; A step of forming a cylindrical body by processing the base material into a cylindrical shape; a step of housing the cylindrical body in a housing member having a compression element, and compressing the cylindrical body radially inward in a point-like manner by the compression element disposed between an inner surface of the housing member and an outside of the cylindrical body; a step of heating the compression element while the cylindrical body is pressed in a radially inward manner in a point-like manner, thereby deforming the surface of the covering portion into a shape in a pressurized state; Equipped with the covering portion extends in the extending direction of the weft yarn so as to cover at least a part of a surface of the warp yarn disposed between the pair of the second region side first portions in the extending direction of the weft yarn and a part of a surface of the warp yarn disposed between the pair of the third region side first portions in the extending direction of the weft yarn, The covering portion is configured to be movable in the radial direction of the artificial blood vessel relative to a surface of a warp yarn disposed between a pair of first portions on the second region side in the extending direction of the weft yarn and a surface of a warp yarn disposed between a pair of first portions on the third region side in the extending direction of the weft yarn in response to a movement of the artificial blood vessel. method.

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