Artificial blood vessel and method for manufacturing the same

Abstract

To provide an artificial blood vessel which hardly causes fraying when the artificial blood vessel is cut.SOLUTION: An artificial blood vessel VE, in which mountains M and valleys V are alternately formed in an axial direction, includes a warp 1 extending along an axial direction and a weft 2 extending along a circumferential direction of the artificial blood vessel VE. The warp 1 has positions in the circumferential direction aligned at a pair of tops Mt1 and Mt2 of the adjacent mountains in the axial direction, and extends in a wavy shape when the artificial blood vessel VE is viewed in a radial direction such that a position at a bottom Vb of the valley V between the pair of mountains M is circumferentially deviated relative to the positions at the pair of tops Mt1 and Mt2 of the mountains M.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an artificial blood vessel and a method for producing the artificial blood vessel. [Background technology]

[0002] Artificial blood vessels are used, for example, to replace diseased biological blood vessels. Artificial blood vessels are cut to a predetermined size and shape depending on the treatment site, and then sutured to the blood vessels of the human body.

[0003] Since artificial blood vessels may be bent while in the human body, they are preferably flexible and resistant to buckling when bent. To achieve this performance, artificial blood vessels with a pleated structure, in which multiple peaks and valleys are continuously formed in the axial direction of the artificial blood vessel, are known, as shown in Patent Document 1, for example. In Patent Document 1, the pleated artificial blood vessel is formed by subjecting a cylindrical structure without a pleated structure to a predetermined process. Specifically, a round rod wound with a spiral wire is inserted inside the cylindrical structure, and another wire is spirally wound around the outside of the cylindrical structure. As a result, the cylindrical structure is subjected to external force applied by the wire and restrained, and then sintered to form a pleated artificial blood vessel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 63-54171 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the tubular structure is made of torsion lace or warp knitting, but the tubular structure may also be made of a woven structure of warp and weft threads. For woven artificial blood vessels, there is a demand for artificial blood vessels that are less likely to unravel the cut weft threads when the artificial blood vessel is cut obliquely, for example.

[0006] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an artificial blood vessel that is less likely to unravel when cut, and a method for manufacturing the artificial blood vessel. [Means for solving the problem]

[0007] The artificial blood vessel of the present invention is an artificial blood vessel in which peaks and valleys are alternately formed in the axial direction, and the artificial blood vessel has warp threads extending along the axial direction and weft threads extending along the circumferential direction of the artificial blood vessel, and the warp threads extend in a wavy pattern when viewed radially of the artificial blood vessel so that the positions in the circumferential direction are aligned at the tops of a pair of peaks adjacent in the axial direction, and the position of the bottom of the valley between the pair of peaks is shifted in the circumferential direction relative to the position at the tops of the pair of peaks.

[0008] Furthermore, the method for manufacturing an artificial blood vessel of the present invention is the method for manufacturing the above-mentioned artificial blood vessel, and includes the steps of: preparing a tubular body formed by a woven structure of the warp threads and the weft threads; arranging the tubular body outside a molding core having convex portions and concave portions corresponding to the peaks and valleys; with the tubular body arranged outside the molding core, wrapping a winding member around part of the circumferential direction of the tubular body outside the molding core, along the concave portions of the molding core; with the winding member wrapped around the tubular body, rotating the side of the tubular body not wrapped with the winding member by a predetermined amount in the axial direction relative to the side on which the winding member is wrapped; and firing the tubular body in which the peaks and valleys are formed by the winding member. [Effects of the Invention]

[0009] According to the artificial blood vessel and the method for producing the artificial blood vessel of the present invention, it is possible to provide an artificial blood vessel that is less likely to unravel when cut. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view of an artificial blood vessel according to one embodiment of the present invention. [Figure 2] FIG. 2 is a partial enlarged view of region II in FIG. [Figure 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] FIG. 2 is a schematic enlarged view of the artificial blood vessel of FIG. 1 as viewed in the radial direction. [Figure 5] 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 6] 1 is a schematic view of a state in which a cylindrical body is arranged on the outside of a molding core material, as viewed in the axial direction. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] An artificial blood vessel and a method for manufacturing an artificial blood vessel according to one embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment shown below is merely an example, and the artificial blood vessel and the method for manufacturing an artificial blood vessel of the present invention are not limited to the following embodiment.

[0012] In this specification, the expressions "perpendicular to A" and similar expressions do not refer only to a direction that is completely perpendicular to A, but also refer to a direction that is approximately perpendicular to A. In this specification, the expressions "parallel to B" and similar expressions do not refer only 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 expressions "C-shape" and similar expressions do not refer only to a perfect C-shape, but also refer to a shape that visually resembles a C-shape (approximately a C-shape).

[0013] 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.

[0014] Artificial blood vessels are used, for example, to replace diseased biological blood vessels and to bypass the biological blood vessels. As shown in Figures 1 and 2, the artificial blood vessel VE of this embodiment has peaks M and valleys V formed alternately in the direction of axis X (see Figure 1). By forming the peaks M and valleys V alternately in the artificial blood vessel VE, the artificial blood vessel can be made flexible and is less likely to kink when bent. The shape of the artificial blood vessel VE is not particularly limited as long as it has peaks M and valleys V, but 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.

[0015] The diameter of the artificial blood vessel VE can be changed depending on the site of use, etc., 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 but less than 10 mm, such as 6 mm or 8 mm (for 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 can be changed appropriately depending on the inner diameter and length of the artificial blood vessel used, and is not particularly limited. For example, the thickness of the artificial blood vessel VE can be 0.1 to 2 mm.

[0016] The length of the artificial blood vessel VE in the direction of axis 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 direction of axis X can be 100 to 1000 mm. When the artificial blood vessel VE is to be transplanted into 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 direction of axis X, or may be cut obliquely at a predetermined angle relative to the direction of axis X (see, for example, the two-dot chain line CL in Figure 1).

[0017] 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 depending on the required kink resistance. For example, in the case of an artificial blood vessel with an outer diameter of 15 mm, 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. Furthermore, the spacing (pitch) in the axial direction X between the apex Mt of a peak M of the artificial blood vessel VE (see FIG. 2) and the apex Mt of an adjacent peak M of the artificial blood vessel VE is not particularly limited, but can be, for example, 10 to 30%, preferably 15 to 25% of the outer diameter of the artificial blood vessel VE (the outer diameter at the apex Mt of the peak M). Furthermore, the depth from the apex 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%, preferably 5 to 15% of the outer diameter of the artificial blood vessel VE.

[0018] Furthermore, in this embodiment, the curvature at the tops Mt of the peaks M is smaller than the curvature at the bottoms Vb of the valleys V (in this embodiment, the radius of curvature at the tops Mt of the peaks M is larger than the radius of curvature at the bottoms Vb of the valleys V). Note that "the curvature at the tops Mt of the peaks M is smaller than the curvature at the bottoms Vb of the valleys V" means that the degree of curvature of the peaks Mt of the peaks M along the axial direction X is smaller than the degree of curvature of the bottoms Vb of the valleys V along the axial direction X (the curve of the peaks M is gentler than the curve of the valleys V), and the peaks M and the valleys V do not need to form completely arcuate surfaces. If the curvature at the tops Mt of the peaks M is smaller than the curvature at the bottoms Vb of the valleys V, stress will be concentrated at the valleys V when an external force is applied to the artificial blood vessel VE, making it easier for the artificial blood vessel VE to bend starting from the valleys 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). bottom The radius of curvature of Vb is 2 to 3% (and Yamabe M of Top Mt than the radius of curvature of small) The artificial blood vessel VE can be easily bent, which makes it difficult for the bent artificial blood vessel VE to return to its original shape, thereby reducing the load on the connection portion between the artificial blood vessel VE and the blood vessel, etc. The curved portions at the tops Mt of the peaks M and the curved portions at the bottoms Vb of the valleys V can be connected by flat portions 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°. The angle θ between the flat portion PL1 on one side and the flat portion PL2 on the other side can be set appropriately depending on the diameter of the artificial blood vessel, the height of the peaks, the height and pitch of the valleys, etc.

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

[0020] In this embodiment, the artificial blood vessel VE is formed with a woven fiber structure. 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 (the 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 (the 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 (the axial X direction of the artificial blood vessel VE) is referred to as D1. In addition, in FIG. 3, the weft threads 2 extend in the horizontal direction, and the extending direction of the weft threads 2 (the circumferential direction of the artificial blood vessel VE) is referred to as D2. In Figure 3, the black (dotted) areas indicate the areas where the warp threads 1 emerge on the outer surface of the artificial blood vessel VE, and the white areas indicate the areas where the weft threads 2 emerge on the outer surface of the artificial blood vessel VE. Note that the loom for manufacturing the artificial blood vessel VE is not particularly limited.

[0021] In this embodiment, the artificial blood vessel VE has a first region R1 in which warp yarns 1 and weft yarns 2 are woven in a plain weave, as shown in Fig. 3. The artificial blood vessel VE also has, on one surface of the artificial blood vessel VE (the outer surface of the artificial blood vessel VE in this embodiment), a second region R2 having a second-region-side first portion R21 in which the warp yarns 1 cross over multiple weft yarns 2 and a second-region-side second portion R22 in which the warp yarns 1 extend across a single weft yarn 2. The artificial blood vessel VE also has, on one surface of the artificial blood vessel VE (the outer surface of the artificial blood vessel VE in this embodiment), a third region R3 having a third-region-side first portion R31 in which the warp yarns 1 cross over multiple weft yarns 2 and a third-region-side second portion R32 in which the warp yarns 1 extend across a single weft yarn 2. The first region R1, the second region R2, and the third region R3 are alternately formed in the extending direction D2 of the weft yarns 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 extending direction D2 of the weft yarn 2. The second-region-side first portion R21 is adjacent to the third-region-side second portion R32 in the extending direction D2 of the weft yarn 2, and the second-region-side second portion R22 is adjacent to the third-region-side first portion R31 in the extending direction D2 of the weft yarn 2. In addition, in this embodiment, the warp yarns 1 are made of multifilament yarns. When the artificial blood vessel VE of this embodiment has the above-mentioned configuration, as will be described later, the warp yarns 1 made of multifilament yarns that extend long without being restrained in the second-region-side first portion R21 or the third-region-side first portion R31 spread toward the plain-woven first region R1 (and toward the front of the paper in FIG. 3 ) Due to the three-dimensional structure of the warp yarns 1, when blood seeps out through the gaps between the fibers in the plain weave first region R1, the blood is prevented from leaking and is retained within the three-dimensional structure. The blood coagulates in this retained state, improving the resistance to blood leakage. The configuration and weaving structure of each part of the artificial blood vessel VE are explained below.

[0022] <Warp composition> The warp threads 1 are fibers that extend in one direction among the fibers that make up the artificial blood vessel VE. In this embodiment, the warp threads 1 extend in the axial direction X of the artificial blood vessel VE. The warp threads 1 are made of a material that is applicable to a fabric artificial blood vessel formed by a woven fiber structure. The material of the warp threads 1 is not particularly limited as long as it is a material that is applicable to a fabric artificial blood vessel. For example, the material of the warp threads 1 can be polyester, polytetrafluoroethylene, polyamide, etc. Alternatively, a composite material composed of two or more applicable materials with different properties such as melting point and stretch rate can be used. For example, a synthetic fiber can be made by combining polyethylene terephthalate (PET) and polytrimethylene terephthalate (PTT) during the spinning stage to form a single long fiber with a spiral crimp. For example, if 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 will easily expand in the extension direction D2 of weft thread 2, thereby improving the blood retention ability and blood leakage resistance.

[0023] Each of the warp yarns 1 may be either a monofilament yarn or a multifilament yarn, but in this embodiment, it is composed of a multifilament yarn. The fineness of the warp yarns 1 is not particularly limited. For example, if the warp yarns 1 are monofilament yarns, the single warp yarn fineness can be 15 to 100 dtex, preferably 20 to 75 dtex. If the warp yarns 1 are multifilament yarns, the single warp yarn fineness can be 0.25 to 2.50 dtex, preferably 0.50 to 2.00 dtex, and the total warp yarn fineness can be 2 to 2500 dtex, preferably 6 to 1600 dtex, more preferably 10 to 540 dtex, and even more preferably 30 to 200 dtex. By setting the single warp yarn fineness and the total warp yarn fineness within the above ranges, the warp yarns 1 in the second region R2 and the third region R3 can be effectively spread toward the first region R1. Therefore, when blood seeps through the gaps in the first region R1, the warp yarns 1 in the second region R2 and the third region R3 prevent the blood from leaking out and are held in place by the three-dimensional structure of the warp yarns 1, allowing the blood to coagulate while held in place, thereby improving leakage resistance. The "single yarn fineness" refers to the fineness per 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 filaments constituting one warp yarn (hereinafter referred to as the number of filaments) is not particularly limited. 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 per weft yarn 2 and the number of warp yarns 1 spanning multiple weft yarns 2 in the second region R2 is one, the number of filaments per warp yarn 1 can be 8 to 1,000, preferably 12 to 800, more preferably 20 to 270, and even more preferably 60 to 100. As will be described later, when the number of filaments per warp thread 1 is 0.8 to 1.2 times the number of filaments per weft thread 1 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.

[0024] The weft threads 2 are fibers that make up the artificial blood vessel VE and extend in a direction that intersects with the warp threads 1. 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 fabric artificial blood vessel that is formed with a woven fiber structure. The material of the weft threads 2 is not particularly limited as long as it is applicable to a fabric artificial blood vessel. For example, the material of the weft threads 2 can be polyester, polytetrafluoroethylene, polyamide, etc.

[0025] Each weft yarn 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. For example, when the weft yarn 2 is a monofilament yarn, the single weft yarn fineness can be 15 to 100 dtex, preferably 20 to 75 dtex. When each weft yarn 2 is a multifilament yarn, the single weft yarn fineness can be 0.25 to 2.50 dtex, preferably 0.50 to 2.00 dtex, and the total weft yarn fineness 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" refers to the fineness of each filament (monofilament or multifilament) constituting the weft yarn 2, and the "total fineness" refers to 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 multifilament yarn, the number of filament yarns constituting one weft yarn can be 4 to 500, preferably 6 to 400, more preferably 10 to 135, and even more preferably 30 to 50.

[0026] The first region R1 is a plain-woven portion of the warp yarns 1 and the weft yarns 2. In FIG. 3, the first region R1 is a region where the warp yarns 1a, 1b, 1e, 1f, 1i, and 1j intersect with the weft yarns 2 (weft yarns 2a to 2l). The first region R1 improves the strength of the artificial blood vessel VE, particularly the tensile strength (in the axial X direction of the artificial blood vessel VE). The first region R1 extends along the extending direction D1 of the warp yarns 1, and also extends in the axial X direction of the artificial blood vessel VE. A plurality of first regions R1 are arranged spaced apart from each other at predetermined intervals in the extending direction D2 of the weft yarns 2. A second region R2 and a third region R3 are arranged between one first region R1 and another first region R1 in the extending direction D2 of the weft yarns 2.

[0027] In this embodiment, as shown in FIG. 3, the first region R1 is formed by plain weaving two warp threads 1a and 1b (warp threads 1e and 1f or warp threads 1i and 1j) and multiple weft threads 2a to 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 threads 1 are multifilament yarns, the term "number of warp threads" refers not to the number of filaments constituting the multifilament yarn, but to the number of warp threads 1 each consisting of multiple filament yarns. 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 more likely to be three-dimensionally covered by the warp yarns 1 of the second-region-side first portion R21 and the warp yarns 1 of the third-region-side first portion R31, and when blood seeps out from the first region R1, the three-dimensional structure of the warp yarns 1 of the second-region-side first portion R21 and the warp yarns 1 of the third-region-side first portion R31 holds the blood and causes it to clot while held, thereby reducing the amount of blood leaking from the artificial blood vessel VE. Furthermore, in the artificial blood vessel VE, the ratio of the number of warp yarns 1 in the first region R1 to the total number of warp yarns 1 arranged in the extension direction D2 of the weft yarns 2 in the first region R1 to the third region R3 (number of warp yarns in the first region R1 / total number of warp yarns) is not particularly limited, but can 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 ranges, the strength of the artificial blood vessel VE can be increased while reducing the amount of blood leakage from the artificial blood vessel VE.

[0028] The second region R2 has a second-region-side first portion R21 where the warp yarn 1 crosses multiple weft yarns 2, and a second-region-side second portion R22 where the warp yarn 1 crosses one weft yarn 2. As shown in FIG. 3, the second-region-side first portion R21 and the second-region-side second portion R22 are alternately arranged in the extending direction D1 of the warp yarn 1. Since the second region R2 has the second-region-side first portion R21 and the second-region-side second portion R22, the artificial blood vessel VE can be made more flexible than an artificial blood vessel VE entirely having a plain weave structure. The portion of the warp yarn 1c in the second region R2 may be composed of a single warp yarn or multiple warp yarns. The number of warp yarns 1 in the second region R2 can be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0029] The second-region-side first portion R21 is a woven portion in which the warp yarns 1 cross multiple weft yarns 2. In this embodiment, warp yarns 1c, 1g, 1k, etc. cross multiple weft yarns 2. In the second-region-side first portion R21, the warp yarns 1 cross multiple weft yarns 2, making the artificial blood vessel VE more flexible in that portion than in a plain weave structure. Furthermore, when the warp yarns 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 extending direction D1 of the warp yarns 1 are bound by the weft yarns 2 of the second-region-side second portion R22 (see portion P1 in Figure 3). In this case, the second-region-side first portion R21 of the warp yarns 1, which are made of multifilament yarns with both ends bound, forms a three-dimensional structure in which the center portion in the extending direction D1 of the warp yarns 1 extends in the extending direction D2 of the weft yarns 2 (note that this three-dimensional structure also extends left and right and toward the front of the page in Figure 3). Therefore, the plain weave first region R1 adjacent to the second region-side first portion R21 in the extending direction D2 of the weft 2 is partially covered by the expanded multifilament yarns of the second region-side first portion R21. Due to this three-dimensional structure of the warp 1, when blood seeps through the inter-fiber gaps in the plain weave first region R1, the seeped blood is retained in the gaps between the filaments in the three-dimensional structure formed by the multifilaments. This allows the blood to coagulate in a retained state, improving 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 extending direction D2 of the weft 2 is also partially covered by the expanded multifilament yarns of the second region-side first portion R21. This also covers the gaps in the third region-side second portion R32 with the multifilament yarns of the second region-side first portion R21, making it less likely for blood in the artificial blood vessel VE to leak to the outside.

[0030] In the second region side first portion R21 (from the time when the warp threads 1 emerge from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) until they reach the other surface), the number of weft threads of the weft threads 2 that the warp threads 1 cross over is not particularly limited, but can 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 threads 2 that the warp threads 1 cross over to within the above range in the second region side first portion R21, it becomes easier to spread the multifilament yarns of the warp threads 1 in the extending direction D2 of the weft threads 2, and the artificial blood vessel VE can be maintained at a predetermined strength.

[0031] 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 where they cross over multiple weft threads 2. For example, the second-region-side first portion R21 (second region R2) may be composed of multiple (two) warp threads (where each of warp threads 1c, 1g, and 1k is composed of multiple warp threads). Furthermore, 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 multiple weft threads 2.

[0032] The second-region-side second portion R22 is a portion woven so 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 emerges 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 that 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 in the weft thread 2 in the second-region-side first portion R21 (three in FIG. 3) is equal to the number of weft threads in the weft thread 2 in the second-region-side second portion R22 (three in FIG. 3).

[0033] The third region R3 has a third-region-side first portion R31 where the warp yarn 1 crosses multiple weft yarns 2, and a third-region-side second portion R32 where the warp yarn 1 crosses one weft yarn 2. As shown in FIG. 3, the third-region-side first portion R31 and the third-region-side second portion R32 are alternately arranged in the extending direction D1 of the warp yarn 1. Because the third region R3 has the third-region-side first portion R31 and the third-region-side second portion R32, the artificial blood vessel VE can be made more flexible than an artificial blood vessel VE entirely having a plain weave structure. The portion of the warp yarn 1d in the third region R3 may be composed of a single warp yarn or multiple warp yarns. The number of warp yarns 1 in the third region R3 can be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0034] The third-region-side first portion R31 is a woven portion in which the warp yarns 1 cross multiple weft yarns 2. In this embodiment, warp yarns 1d, 1h, 1l, etc. cross multiple weft yarns 2. In the third-region-side first portion R31, the warp yarns 1 cross multiple weft yarns 2, making the artificial blood vessel VE more flexible in that portion than in a plain weave structure. Furthermore, if the warp yarns 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 extending direction D1 of the warp yarns 1 are bound by the weft yarns 2 of the third-region-side second portion R32 (see portion P2 in Figure 3). In this case, the third-region-side first portion R31 of the warp yarns 1, which are made of multifilament yarns with both ends bound, forms a three-dimensional structure in which the center portion in the extending direction D1 of the warp yarns 1 extends in the extending direction D2 of the weft yarns 2 (note that this three-dimensional structure also extends left and right and toward the front of the page in Figure 3). Therefore, the plain weave first region R1 adjacent to the third region-side first portion R31 in the extending direction D2 of the weft 2 is partially covered by the expanded multifilament yarns of the third region-side first portion R31. Due to this three-dimensional structure of the warp 1, when blood seeps through the inter-fiber gaps in the plain weave first region R1, the seeped blood is retained in the gaps between the filaments in the three-dimensional structure formed by the multifilaments. This allows the blood to coagulate in a retained state, improving blood leakage resistance. Furthermore, in this embodiment, the second region-side second portion R22 adjacent to the third region-side first portion R31 in the extending direction D2 of the weft 2 is also partially covered by the expanded multifilament yarns of the third region-side first portion R31. As a result, gaps in the second region-side second portion R22 are also covered by the multifilament yarns of the third region-side first portion R31, making it less likely for blood in the artificial blood vessel VE to leak to the outside.

[0035] In the third region side first portion R31 (from the time when the warp threads 1 emerge from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) until they reach the other surface), the number of weft threads of the weft threads 2 that the warp threads 1 cross over is not particularly limited, but can 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 threads 2 that the warp threads 1 cross over to the above range in the third region side first portion R31, it is easy to spread the multifilament yarns of the warp threads 1 in the extending direction D2 of the weft threads 2, and the artificial blood vessel VE can be maintained at a predetermined strength.

[0036] 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 where they cross over multiple weft threads 2. For example, the third-region-side first portion R31 (third region R3) may be composed of multiple (two) warp threads (where each of warp threads 1d, 1h, and 1l is composed of multiple warp threads). Furthermore, 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 multiple weft threads 2.

[0037] The third-region-side second portion R32 is a portion woven so 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 emerges from the other surface of the artificial blood vessel VE to one surface (the surface shown in FIG. 3) until it returns to 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 in 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 in the weft thread 2 in the third-region-side second portion R32 (three in FIG. 3).

[0038] The woven structure of the artificial blood vessel VE is not limited to the above-mentioned woven structures, and the artificial blood vessel VE may have, in whole or in part, a plain weave structure, a twill weave structure, a satin weave structure, or a composite structure of these weave structures.

[0039] FIG. 4 is a schematic enlarged view of the artificial blood vessel VE viewed radially, i.e., viewed from the outside toward the axis X of the artificial blood vessel VE (or cut and unfolded along the axis X). In FIG. 4, dots indicate warp yarns 1, and non-dotted yarns indicate weft yarns 2. Note that FIG. 4 shows the same orientation as the artificial blood vessel VE in FIG. 1, rotated 90 degrees from the woven structure diagram in FIG. 3. Also, in FIG. 4, the peaks Mt1 and Mt2 of the peaks M and the bottoms Vb of the valleys V of the artificial blood vessel VE are indicated by two-dot chain lines. Note that FIG. 4 is exaggerated to better illustrate how the warp yarns 1 extend; the gaps between the warp yarns 1 and weft yarns 2 in the schematic diagram of FIG. 4 are actually covered by the warp yarns 1 and weft yarns 2 in the woven structure of the actual artificial blood vessel VE.

[0040] In this embodiment, as shown in Fig. 4, the warp yarns 1 extend in a wavy pattern when viewed radially of the artificial blood vessel VE such that the crests Mt1, Mt2 of a pair of adjacent peaks M in the axial direction X are aligned in the circumferential direction (the vertical direction in Fig. 4), and the bottom Vb of the valley V between a pair of peaks M is offset in the circumferential direction from the crests Mt1, Mt2 of the pair of peaks M. Here, "the crests Mt1, Mt2 of a pair of adjacent peaks M are aligned in the circumferential direction" does not mean that the crests Mt1, Mt2 of a pair of adjacent peaks M need not be completely aligned in the circumferential direction; as long as the warp yarns 1 are wavy, the crests Mt1, Mt2 of a pair of adjacent peaks M may be slightly offset in the circumferential direction. Note that, because misalignment or deformation may occur in a portion of the length of the warp yarns 1 during the formation of the artificial blood vessel, the warp yarns 1 do not necessarily need to be aligned in the circumferential direction. Furthermore, "extending in a wavy manner when viewed radially of the artificial blood vessel VE" means that when a single warp thread 1 extending from one end of the artificial blood vessel VE in the direction of axis X to the other end is viewed radially of the artificial blood vessel VE, the warp thread 1 extends in a meandering manner, repeatedly displacing in the circumferential direction of the artificial blood vessel VE. Specifically, as shown in Fig. 4, of each warp thread 1 of the artificial blood vessel VE, the portion extending from the top Mt1 of the peak M to the bottom Vb of the valley V (see region A1 in Fig. 4) extends while being displaced in one circumferential direction (as its radial position on the artificial blood vessel VE moves closer to axis X). Furthermore, of each warp thread 1 of the artificial blood vessel VE, the portion extending from the bottom Vb of the valley V to the top Mt2 of the peak M (see region A2 in Fig. 4) extends while being displaced in the other circumferential direction (as its radial position on the artificial blood vessel VE moves away from axis X).

[0041] As described above, when the warp threads 1 extend in a wavy pattern so that the positions of the bottoms Vb of the valleys V are shifted circumferentially relative to the positions of the crests Mt1 and Mt2 of the peaks M, the density of the warp threads 1 (the amount of warp threads 1 per unit area of ​​the artificial blood vessel VE) is higher than when the warp threads extend linearly without any circumferential shift. In this case, the warp threads 1 are well entangled with the weft threads 2, and the weft threads 2 are more tightly constrained by the warp threads 1. Therefore, when the artificial blood vessel VE is cut, for example, the unraveling of the weft threads 2 can be suppressed. More specifically, for example, when the warp threads do not extend in a wavy pattern as shown in FIG. 4 but extend linearly when viewed radially of the artificial blood vessel (when the warp threads extend straight from side to side in FIG. 4), the density of the warp threads per unit area is lower. In this case, the entanglement between the warp threads and the weft threads is looser, and the weft threads are not as tightly constrained by the warp threads. Therefore, when the artificial blood vessel VE is cut and a doctor or other professional touches the area around the cut portion of the artificial blood vessel, the weft threads may become loose. In particular, when the artificial blood vessel VE is cut obliquely along the cutting line indicated by reference symbol CL in FIG. 1 , half or more of the looped weft threads are removed in the circumferential direction in the end region E of the artificial blood vessel VE. Therefore, in the end region E, the weft threads are cut to less than half of the circumferential length of the artificial blood vessel VE and are simply supported in a state where they intersect with the warp threads, making them prone to unraveling. If the weft threads are not tightly constrained by the warp threads, they may become loose in the end region E between the time the artificial blood vessel is cut and the time it is sutured to the living blood vessel. This loosening may contribute to blood leakage after the artificial blood vessel is implanted in the living body. In this embodiment, as described above, the position of the bottom Vb of the valley V of the warp thread 1 extends in a wavy manner so as to be circumferentially shifted relative to the positions of the peaks Mt1 and Mt2 of the peaks M, thereby enabling the weft thread 2 to be tightly constrained, and even if the artificial blood vessel VE is cut at an angle, the weft thread 2 can be prevented from unraveling.

[0042] The circumferential positional deviation L1 (see FIG. 4) between the position of the bottom Vb of the valley V of the warp yarn 1 and the position of the crests Mt1, Mt2 of the peaks M can be appropriately changed depending on the flexibility and kink resistance required of the artificial blood vessel. For example, the positional deviation L1 can be set to 5 to 25%, more preferably 8 to 20%, of the distance L2 (see FIG. 4) between the crests Mt1, Mt2 of the peaks M.

[0043] Furthermore, since the positions of the crests Mt of the warp threads 1 are aligned in the circumferential direction of the artificial blood vessel VE, the warp threads 1 extend in a wavy pattern from one end of the artificial blood vessel VE to the other, and extend along the axis X of the artificial blood vessel VE as a whole. If the warp threads extend at an angle with respect to the axis X from one end of the artificial blood vessel to the other (see the two-dot chain line LN in FIG. 1), the artificial blood vessel will twist around the axis X or bend relative to the axis X in its natural state (unloaded state). On the other hand, in this embodiment, the warp threads 1 extend in a wavy pattern from one end of the artificial blood vessel VE to the other, and extend along the axis X of the artificial blood vessel VE as a whole, so that the artificial blood vessel VE is prevented from twisting around the axis X or bending relative to the axis X in its natural state.

[0044] In this embodiment, as described above, the artificial blood vessel VE has 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, which are alternately arranged in the extending direction D2 of the weft yarns 2, the second-region-side first portion R21 being adjacent to the third-region-side second portion R32 in the extending direction D2 of the weft yarns 2, and the second-region-side second portion R22 being adjacent to the third-region-side first portion R31 in the extending direction D2 of the weft yarns 2, and the warp yarns 1 are made of multifilament yarns. In this case, the warp yarns 1 made of multifilament yarns are bundled by the weft yarns 2 at both ends of the portion where they cross multiple weft yarns 2 (see portions P1 and P2 in FIG. 3 ). A strong binding force is generated in the weft yarn 2 due to the reaction force of the warp yarn 1 multifilament yarns that are bound by the weft yarn 2 trying to spread out. Therefore, the weft yarn 2 is bound by the warp yarn 1, and the unraveling of the weft yarn 2 is further suppressed.

[0045] 3, the multifilament yarns of the warp yarns 1 in the second-region-side first portion R21 spread in the extending direction D2 of the weft yarns 2, partially covering the first region R1 adjacent to the second-region-side first portion R21 and filling gaps (porosity) formed at the four corners of the intersections of the warp yarns 1 and weft yarns 2 formed in the first region R1. Furthermore, the multifilament yarns of the warp yarns 1 in the third-region-side first portion R31 spread in the extending direction D2 of the weft yarns 2, partially covering the first region R1 adjacent to the third-region-side first portion R31, and filling gaps (porosity) formed at the four corners of the intersections of the warp yarns 1 and weft yarns 2 formed in the first region R1 with the multifilament yarns of the second-region-side first portion R21 and the third-region-side first portion R31. Therefore, when blood seeps out from the gaps between the fibers in the plain weave first region R1, the three-dimensional structure of the warp yarns 1 retains the seeping blood in the gaps between the filaments in the three-dimensional structure formed by the multifilament, allowing the blood to clot without flowing out. This improves blood leakage resistance. In addition, in this embodiment, the multifilament yarns of the warp yarns 1 in the second-region-side first portion R21 partially cover the third-region-side second portion R32 adjacent to the second-region-side first portion R21, thereby covering gaps (porosity) formed at the intersections of the warp yarns 1 and weft yarns 2 in the third-region-side second portion R32. Furthermore, the multifilament yarns of the warp yarns 1 in the third-region-side first portion R31 partially cover the second-region-side second portion R22 adjacent to the third-region-side first portion R31, thereby covering gaps (porosity) formed at the intersections of the warp yarns 1 and weft yarns 2 in the second-region-side second portion R22. Therefore, blood in the artificial blood vessel VE is less likely to leak to the outside through the gap between the third region-side second portion R32 and the second region-side second portion R22, improving the blood leakage resistance of the artificial blood vessel VE.

[0046] Furthermore, in this embodiment, a first region R1 having a plain weave structure and a second region R2 and a third region R3 having a woven structure different from the plain weave structure are alternately formed in the extending direction D2 of the weft yarn 2. Therefore, the first regions R1 provided at a predetermined interval in the extending direction D2 of the weft yarn 2 ensure a predetermined strength of the artificial blood vessel VE, while the second regions R2 and the third regions R3 provide a predetermined flexibility required for the artificial blood vessel VE. Therefore, when an artificial blood vessel VE is formed with the woven structure shown in Fig. 3, not only is blood leakage resistance improved, but both the strength and flexibility required for the artificial blood vessel VE can be achieved.

[0047] 3, in this embodiment, the second-region-side first portion R21 and the third-region-side first portion R31 are configured to extend continuously in a zigzag pattern in the extension direction D1 of the warp threads 1. In this case, 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, which extend in the extension direction D2 of the weft threads 2, do not interfere with each other, and the extension of the warp threads 1 is continuous in the extension direction D1 of the warp threads 1, so that the three-dimensional structure can further enhance blood absorbency.

[0048] It is preferable that the average width of the maximum spread of the warp yarns 1 in the extension direction D2 of the weft yarns 2 in the second-region-side first portion R21 and the third-region-side first portion R31 is larger than the average width of the maximum spread of the warp yarns 1 in the first region R1 in the extension direction D2 of the weft yarns 2. In this case, the gaps between the first region R1, the second-region-side second portion R22, and the third-region-side second portion R32 are covered over a wide area by the warp yarns 1 in the second-region-side first portion R21 and the third-region-side first portion R31. Therefore, blood that seeps out from the gaps between the first region R1, the second-region-side second portion R22, and the third-region-side second portion R32 is more easily retained, further improving blood leakage resistance. The average width of the maximum spread of the warp thread 1 in the extension direction D2 of the weft thread 2 in the second region side first portion R21 and the third region side first portion R31 is not particularly limited, but can be, for example, 2.0 to 4.0 times the average width of the maximum spread of the warp thread 1 in the first region R1 in the extension direction D2 of the weft thread 2.

[0049] The "average width of the maximum spread of the warp thread 1 in the extension direction D2 of the weft thread 2 of the second region side first portion R21 and the third region side first portion R31" can be calculated, for example, by measuring the width Wa (not shown) of the portion where the warp thread 1 of the second region side first portion R21 and the third region side first portion R31 spreads the most in a predetermined area (e.g., 1 mm x 1 mm) of the artificial blood vessel for a predetermined number of meters (e.g., 10 or more) and calculating the average value ((Wa1 + Wa2 + ··· Wam) / m).

[0050] In the artificial blood vessel VE, the wefts 2 may be made of multifilament yarns, and the total number of filaments in the warps 1 (warps 1c, 1d, 1g, 1h, 1k, and 1l in FIG. 3) crossing multiple wefts 2 in the second region R2 and the third region R3 may be 1.5 times or more, preferably 1.5 to 3.0 times, the number of filaments per weft 2. Here, "the total number of filaments in the warps 1 crossing multiple wefts 2" refers to the number of filaments in one warp 1 crossing multiple wefts 2 in one second region R2 or one third region R3 when the warp 1 crossing multiple wefts 2 has only one warp 1. Alternatively, when the warp 1 crossing multiple wefts 2 has multiple warp 1s (for example, two or three), the total number of filaments in the multiple warps 1 (the number of filaments constituting one warp 1 multiplied by the number of warps, 2 or 3). By having the total number of filaments of the warp yarns 1 spanning multiple weft yarns 2 greater than the number of filaments per weft yarn 2, the multifilament warp yarns 1 spread more easily than the multifilament weft yarns 2, further improving blood leakage resistance. That is, the warp yarns 1, which have a greater total number of filaments than the weft yarns 2, are bound by weft yarns 2 that are thinner (have fewer filaments) than the warp yarns 1 at both ends of the second-region-side first portion R21 and the third-region-side first portion R31 in the extension direction D1 of the warp yarns 1. As a result, strong pressure is applied to the warp yarns 1 by being bound by the thin weft yarns 2, making the warp yarns 1 more likely to spread in the extension direction D2 of the weft yarns 2. Furthermore, the strong pressure applied to the warp yarns 1 applies an even greater reaction force to the weft yarns 2, further improving the effect of preventing the weft yarns 2 from unraveling. Furthermore, when the total number of filaments in the warp threads 1 and the number of filaments per weft thread 2 are set at the above ratio, the number of weft threads 2 is smaller than the number of filaments in the warp threads 1, making it easier to pack the weft threads 2 in the extending direction D1 of the warp threads 1 when weaving an artificial blood vessel. Therefore, by packing the weft threads 2 in the extending direction D1 of the warp threads 1, it is possible to reduce the gaps (porosity) formed at the intersections between the warp threads 1 and the weft threads 2, and the amount of blood leakage itself can be reduced. Therefore, the reduction in the amount of blood leakage itself, which is achieved by making it easier to pack the weft threads 2, combined with the ability of the three-dimensional structure of the warp threads 1 to absorb leaked blood, results in a dramatic improvement in blood leakage resistance.

[0051] In this embodiment, in each of the second region R2 and the third region R3, the number of warp yarns 1 crossing multiple weft yarns 2 is one, and the number of filaments per warp yarn 1 in the second region R2 and the third region R3 is preferably 1.5 times or more, and preferably 1.5 to 3 times, the number of filaments per weft yarn. Specifically, the number of filaments per weft yarn 2 can be 4 to 500, and the number of filaments per warp yarn 1 can be 8 to 1000. As a result, in the second region R2 and the third region R3, the multifilament yarns constituting the warp yarns 1 crossing multiple weft yarns 2 are bundled together in each of the second region R2 and the third region R3, and the number of filaments per warp yarn 1 is greater than the number of filaments in the weft yarn 2. The configuration of the warp yarns 1 and the weft yarns 2 is not limited to the above-described configuration, as long as the total number of filaments in the warp yarns 1 crossing the multiple weft yarns 2 in the second region R2 and the third region R3 is 1.5 times or more the number of filaments per weft yarn 2. For example, in the second region R2 and the third region R3, the number of warp yarns 1 crossing the multiple weft yarns 2 may be two or more, and the number of filaments per warp yarn 1 may be 0.8 to 1.2 times the number of filaments per weft yarn 2 (preferably the same number of filaments). In this case, too, by having two or more warp yarns 1 crossing the multiple weft yarns 2, the total number of filaments in the warp yarns 1 crossing the multiple weft yarns 2 in the second region R2 and the third region R3 is greater than the number of filaments per weft yarn 2. Therefore, the same effects as those described above can be obtained.

[0052] In the second region R2 and the third region R3, the number of filaments in the warp threads 1 (e.g., 1c, 1d, 1g, 1h, 1k, and 1l) spanning multiple weft threads 2 may be greater than the number of filaments per weft thread 2 (e.g., 1.5 to 3 times) and two warp threads 1 may be provided in each of the second region R2 and the third region R3 (e.g., each of 1c, 1d, 1g, 1h, 1k, and 1l is composed of two warp threads). These two warp threads 1, each with a greater number of filaments than the number of filaments per weft thread 2, are bundled together with one weft thread 2 with a smaller number of filaments. In this case, the reaction force applied from the warp thread 1 to one weft thread 2 is greater than when bundling one warp thread or when bundling warps with a smaller number of filaments per weft thread. This further improves the prevention of unraveling of the weft thread 2. As described above, in the second region R2 and the third region R3, the warp threads 1 spread in the extension direction D2 of the weft threads 2 and cover the surface of the weft threads 2. This makes it difficult for the weft threads 2 to be exposed on the surface of the artificial blood vessel VE, and reduces the chances that a doctor or other person will come into contact with the weft threads 2 when touching the artificial blood vessel VE, thereby preventing the weft threads 2 from fraying at the cut portions of the artificial blood vessel VE.

[0053] Next, an example of a method for manufacturing the above-mentioned artificial blood vessel VE will be described. Note that the following manufacturing method is merely an example, and the artificial blood vessel VE may be manufactured by other manufacturing methods. The following description does not limit the artificial blood vessel VE of the present invention and the method for manufacturing the artificial blood vessel VE.

[0054] First, a tubular body C (see FIG. 5) is prepared, which is made of a woven structure of warp threads 1 and weft threads 2, such as the woven structure described above. Note that the "tubular body C" here refers to a tubular base material in which the peaks M and valleys V shown in FIGS. 1 and 2 have not yet been formed (or in which the peaks M and valleys V have only been formed in some parts, with the peaks M and valleys V not yet formed in other parts). The method for forming the tubular body C can be any known method for producing a tubular artificial blood vessel having a predetermined woven structure (an artificial blood vessel without pleats), and therefore a detailed description thereof will be omitted.

[0055] Next, the cylindrical body C is placed on the outside of a molding core 3 (see FIG. 5) 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 the artificial blood vessel VE having peaks M and valleys V of the desired size and shape. In this embodiment, the molding core 3 is configured so that it can cover the outside of the cylindrical body C. 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 C, but the outer diameter of the protrusions 31 may also be slightly larger than the inner diameter of the cylindrical body C. In this embodiment, the molding core 3 is supported rotatably about axis X by a support (not shown) of a molding device including the molding core 3.

[0056] When the tubular body C is placed outside the core material 3, as shown in FIG. 5 , the winding member 4 is wound around a portion of the tubular body C in the circumferential direction along the recessed portion 32 of the core material 3 while the tubular body C is placed outside the core material 3. The winding member 4 is a member for pressing the portion of the tubular body C placed outside the core material 3 against the recessed portion 32 of the core material 3 to form a portion of the tubular body C corresponding to the valley portion V. The winding member 4 is not particularly limited as long as it can form the valley portion V in the tubular body C, but in this embodiment, it can be a wire having a size that can fit between a pair of protruding portions 31 corresponding to a pair of crest portions M. Note that in this embodiment, the winding member 4 is stretched in a tensioned state (see FIG. 6 ), and the core material 3 is rotated around the axis X, whereby the winding member 4 is spirally wound around the outer periphery of the tubular body C, forming the valley portion V in the tubular body C. Alternatively, the valleys V may be formed in the cylindrical body C by moving the winding member 4 so as to spirally wind around the core material 3 to be formed, without rotating the core material 3 to be formed.

[0057] In the process of winding the winding member 4 around the outside of the tubular body C, the tubular body C is pressed toward the molding core 3 by the winding member 4, forming valleys V in the tubular body C. At this time, the winding member 4 is wound around the tubular body C while being pressed by the winding member 4, and the warp threads 1 of the tubular body C are pulled in the circumferential direction by the winding member 4. Therefore, the warp threads 1 are subjected to a circumferentially shifting force by the winding member 4, and are shifted in the circumferential direction relative to the crests Mt of the peaks M that are not pressed (see area A1 in Figure 4). At this time, as the warp threads 1 are shifted (twisted) in the circumferential direction, the warp threads 1 are pulled in the extension direction of the warp threads 1 more than when they extend approximately parallel to the axis X. This further closes the gaps (voids) between the warp threads 1 and the weft threads 2, thereby further reducing blood leakage. Furthermore, in order to form the valleys V, the cylindrical body C is pressed radially inward of the cylindrical body C by the winding member 4 from a flat state along the direction of the axis X shown on the right side of Fig. 5 toward the recesses 32 of the molding core material 3. At this time, the warp threads 1 of the cylindrical body C are pulled in the extending direction of the warp threads 1 while being deformed along the recesses 32. This makes the meshes (gaps) between the warp threads 1 and the weft threads 2 tighter, improving the blood leakage resistance.

[0058] Next, with the winding member 4 wound around the tubular body C, the side of the tubular body C on which the winding member 4 is not wound (the right-hand portion in FIG. 5) is rotated a predetermined amount relative to the side on which the winding member 4 is wound (the left-hand end portion in FIG. 5). By this step, in the step of winding the winding member 4 described above, the circumferential position of the warp yarn 1 is shifted between the crest Mt1 of one peak M and the bottom Vb of the valley V adjacent to the crest Mt1 of the peak M (see area A1 in FIG. 4), but the tubular body C is rotated a predetermined amount so that the crest Mt2 of another peak M adjacent to the first peak M in the axial X direction is aligned with the circumferential position of the crest Mt1 of the first peak M. More specifically, for example, the molding core 3 is rotated around the axis X by an angle of 360° or less (e.g., 90°) to wind the winding member 4 around the tubular body C by a predetermined amount, and then the side of the tubular body C on which the winding member 4 is not wound is slightly rotated so that the crest Mt2 of the peak M coincides with the circumferential position of the crest Mt1 of the peak M. This changes the circumferential position between the crests Mt1 and Mt2 of the peaks M and the bottoms Vb of the valleys V, thereby making the warp threads 1 wavy. The predetermined amount of relative rotation of the tubular body C may be any rotation angle that makes the circumferential positions of the crests Mt1 and Mt2 of a pair of peaks M adjacent to each other in the direction of the axis X of the warp threads 1 substantially the same. There is no particular restriction on the method for setting the "predetermined amount" that is the amount of rotation of the tubular body C. For example, when a winding member 4 is wound over a predetermined length around a cylindrical body (sample) made of the same material and structure, the amount of circumferential misalignment between the crests Mt of the peaks M of the warp threads 1 and the bottoms Vb of the valleys V can be calculated, and the rotation angle of the cylindrical body C that can eliminate the calculated amount of misalignment can be set as the predetermined amount of rotation of the cylindrical body C. Alternatively, the amount of circumferential misalignment between the crests Mt of the peaks M of the warp threads 1 and the bottoms Vb of the valleys V can be measured using a sensor or the like that can detect the circumferential position of the warp threads 1, and the rotation angle of the cylindrical body C that can eliminate the amount of misalignment measured by the sensor or the like can be set as the predetermined amount of rotation of the cylindrical body C.

[0059] The method for relatively rotating the tubular body C by a predetermined amount is not particularly limited, as long as it allows the side of the tubular body C on which the winding member 4 is not wound in the axial direction X to be rotated relative to the side on which the winding member 4 is wound. For example, as shown in FIG. 5, a holding unit 5 capable of holding the portion of the tubular body C on which the winding member 4 is not wound may be provided on the outer side of the tubular body C arranged on the outer side of the molding core 3. The holding unit 5 is configured to rotate the side of the tubular body C on which the winding member 4 is not wound relative to the side on which the winding member 4 is wound. As shown in FIG. 4, this relative rotation twists the warp yarns 1 in the opposite direction (see region A2 in FIG. 4) to the portion of the warp yarns 1 twisted by the winding member 4 (see region A1 in FIG. 4), and allows the crests Mt1 and Mt2 of a pair of adjacent peaks M to be positioned at the same position in the circumferential direction. When the wavy shape of the warp threads 1 is formed by twisting the warp threads 1 so that they are inclined relative to the axial direction X using a holding portion 5 or the like, the entanglement between the warp threads 1 and the weft threads 2 becomes stronger, thereby further improving the resistance to blood leakage.

[0060] The process of winding the winding member 4 around the outside of the cylindrical body C and the process of rotating the side of the cylindrical body C in the axial X direction on which the winding member 4 is not wound by a predetermined amount relative to the side on which the winding member 4 is wound are repeated until the winding member 4 is wound over almost the entire length of the cylindrical body C in the axial X direction. Once the winding member 4 has been wound over almost the entire length of the cylindrical body C in the axial X direction, the cylindrical body C, in which peaks M and valleys V have been formed by the winding member 4, is fired. Once the firing of the cylindrical body C is complete, the cylindrical body C is cooled, and the winding member 4 and molding core 3 are removed, completing the artificial blood vessel VE.

[0061] As shown in FIG. 4 , in the artificial blood vessel VE manufactured by the above manufacturing method, the warp threads 1 extend in a wavy pattern when viewed radially (when the artificial blood vessel VE is cut in the axial direction and unfolded) so that the positions of the bottoms Vb of the valleys V of the warp threads 1 are circumferentially offset relative to the positions of the crests Mt of the peaks M. In this case, the density of the warp threads 1 (the amount of warp threads 1 per unit area of ​​the artificial blood vessel VE) is higher than when the warp threads extend linearly without circumferential offset, and the weft threads 2 are more tightly constrained by the warp threads 1. Therefore, when the artificial blood vessel VE is cut, for example, the unraveling of the weft threads 2 can be suppressed. Furthermore, because the positions of the warp threads 1 at the crests Mt1 and Mt2 of the peaks M are aligned circumferentially of the artificial blood vessel VE, the warp threads 1 extend in a wavy pattern from one end of the artificial blood vessel VE to the other, and extend overall along the axis X of the artificial blood vessel VE. Therefore, the artificial blood vessel VE is prevented from twisting around the axis X or bending relative to the axis X in its natural state. In this embodiment, the artificial blood vessel VE has 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, which are alternately arranged in the extending direction D2 of the weft yarns 2, the second-region-side first portion R21 being adjacent to the third-region-side second portion R32 in the extending direction D2 of the weft yarns 2, and the second-region-side second portion R22 being adjacent to the third-region-side first portion R31 in the extending direction D2 of the weft yarns 2, and the warp yarns 1 are made of multifilament yarns. In this case, the warp thread 1 made of multifilament yarn is bound by the weft thread 2 at both ends of the portion where it crosses over multiple weft threads 2, and a strong binding force is generated in the weft thread 2 due to the reaction force that tries to spread out the multifilament yarn of the warp thread 1 bound by the weft thread 2. Therefore, the weft thread 2 is bound by the warp thread 1, and the unraveling of the weft thread 2 is further suppressed. [Explanation of symbols]

[0062] 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 part 32 recess 4 Winding member 5 Holding part A1: The area of ​​the warp yarn that extends from the top of the peak to the bottom of the valley A2: The area of ​​the warp yarn that extends from the bottom of the valley to the top of the peak C. Cylindrical body CL cutting line D1: Warp extension direction D2 Weft extension direction E. End region of vascular prosthesis L1: Amount of misalignment in the circumferential direction between the bottom of the valley and the top of the peak L2 Spacing between peaks LN: Imaginary line when the warp threads extend from one end of the artificial blood vessel to the other at an angle to the axis M Yamabe The summits of Mt, Mt1, and Mt2 P1: The weft thread portion that binds both ends of the first part on the second region side P2: The weft thread that binds both ends of the first part on the third region side PL, PL1, PL2 Floor Plans R1 1st area R2 2nd area R21 2nd area side 1st part R22 2nd area side 2nd part R3 3rd area R31 3rd area side 1st part R32 3rd area side 2nd part V Tanibe Vb Bottom of valley VE Artificial Blood Vessel X-axis θ is the angle between the flat surface on one side and the flat surface on the other side

Claims

1. An artificial blood vessel in which peaks and valleys are alternately formed in the axial direction, The artificial blood vessel has warp yarns extending along the axial direction and weft yarns extending along the circumferential direction of the artificial blood vessel, the warp threads extend in a wavy pattern when viewed radially of the artificial blood vessel such that the positions in the circumferential direction are aligned at the tops of a pair of axially adjacent peaks, and the positions of the bottoms of the valleys between the pair of peaks are shifted in the circumferential direction relative to the positions of the tops of the pair of peaks.

2. The artificial blood vessel is 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 the 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; and alternate in the extension direction of the weft yarn, the second region side first portion is adjacent to the third region side second portion in the extending direction of the weft yarn, and the second region side second portion is adjacent to the third region side first portion in the extending direction of the weft yarn, 2. The artificial blood vessel according to claim 1, wherein the warp threads are made of multifilament threads.

3. 3. The artificial blood vessel according to claim 2, wherein the second region side first portion and the third region side first portion extend continuously in a zigzag pattern in the extending direction of the warp threads.

4. 4. The artificial blood vessel according to claim 1, wherein the curvature at the top of said peaks is smaller than the curvature at the bottom of said valleys.

5. A method for producing an artificial blood vessel according to any one of claims 1 to 4, comprising: The manufacturing method includes: preparing a tubular body formed by a woven structure of the warp yarns and the weft yarns; placing the cylindrical body on the outside of a molding core having protrusions and recesses corresponding to the peaks and valleys; a step of winding a winding member around a part of the circumferential direction of the cylindrical body along the recess of the shaping core while the cylindrical body is disposed outside the shaping core; a step of rotating a side of the cylindrical body, on which the winding member is not wound, by a predetermined amount relative to a side on which the winding member is wound, in the axial direction, while the winding member is wound around the cylindrical body; a step of firing the cylindrical body in which the peaks and valleys are formed by the winding member; A method for manufacturing an artificial blood vessel, comprising:

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