Artificial blood vessel and method for manufacturing artificial blood vessel

Abstract

The artificial blood vessel is provided with weft yarns and warp yarns formed by multifilament yarns, the artificial blood vessel has a first region woven in a plain weave, a second region having a second-region-side first portion in which a warp yarn spans a plurality of weft yarns, and a second-region-side second portion in which the warp yarn spans one weft yarn. And a third region having a third-region-side first portion in which the warp threads extend across the plurality of weft threads and a third-region-side second portion in which the warp threads extend across one weft thread, the second-region-side first portion and the third-region-side first portion having a covering portion. The covering portion is configured so as to be relatively movable with respect to the surface of the warp yarn disposed between the pair of second region-side first portions and between the pair of third region-side first portions. By means of this configuration, it is possible to provide an artificial blood vessel capable of maintaining flexibility and improving leakproofness.

Description

Artificial blood vessels and methods for manufacturing artificial blood vessels Technical Field

[0001] This invention relates to artificial blood vessels and methods for manufacturing artificial blood vessels. Background Technology

[0002] Artificial blood vessels are used, for example, to replace unhealthy biological blood vessels. As shown in Patent Document 1, artificial blood vessels are constructed from a woven structure of warp and weft yarns. Artificial blood vessels require minimal blood leakage, i.e., high resistance to blood leakage. This resistance can be improved by increasing the fabric density of the warp and weft yarns.

[0003] Prior art literature, patent literature, patent literature 1: Japanese Patent Application Publication No. 2012-139498 Summary of the Invention The technical problem to be solved by the invention However, if the fabric density of the artificial blood vessel is increased, the resistance to blood leakage can be improved, but the flexibility required by the artificial blood vessel will be compromised.

[0004] Therefore, the object of the present invention is to provide an artificial blood vessel that can maintain flexibility and improve resistance to blood leakage, and a method for manufacturing the artificial blood vessel.

[0005] Solution to the technical problem: The artificial blood vessel of the present invention is an artificial blood vessel having weft yarns and warp yarns composed of multifilament yarns, wherein the artificial blood vessel alternately has, in the extension direction of the weft yarns: a first region, which is woven with the warp yarns and the weft yarns in a plain weave; a second region, which has a second region side first portion on one side of the artificial blood vessel, wherein the warp yarns extend across multiple weft yarns and a second region side second portion on one side of the artificial blood vessel, wherein the warp yarns extend across one weft yarn; and a third region, which has a third region side first portion on one side of the artificial blood vessel, wherein the warp yarns extend across multiple weft yarns and a third region side second portion on one side of the artificial blood vessel, wherein the second region side first portion is adjacent to the third region side second portion in the extension direction of the weft yarns, and the second region side second portion is adjacent to the third region side first portion in the extension direction of the weft yarns, wherein the second region side first portion and the third region side first portion have The device has a covering portion, which is composed of a resin layer either in a melt-cured state of the multifilament yarn on the surfaces of the first portion on the second region side and the first portion on the third region side, or coated on the surface of the multifilament yarn. The covering portion covers the multifilament yarn on the first portion on the second region side and the first portion on the third region side in a planar manner. The covering portion extends in the extension direction of the weft yarn in such a way that it covers at least a portion of the surfaces of the warp yarns disposed between a pair of first portions on the second region side in the extension direction of the weft yarn and the surfaces of the warp yarns disposed between a pair of first portions on the third region side in the extension direction of the weft yarn. The covering portion is configured to be able to move radially relative to the surfaces of the warp yarns disposed between a pair of first portions on the second region side in the extension direction of the weft yarn and the surfaces of the warp yarns disposed between a pair of first portions on the third region side in the extension direction of the weft yarn, depending on the movement of the artificial blood vessel.

[0006] Furthermore, the method for manufacturing the artificial blood vessel of the present invention is a method for manufacturing an artificial blood vessel having weft yarns and warp yarns composed of multifilament yarns, wherein the method includes: a step of preparing a substrate, the substrate having alternating first, second, and third regions in the extension direction of the weft yarns, the first region being woven by the warp yarns and the weft yarns in a plain weave structure, the second region having a second region side first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a second region side second portion on one side of the artificial blood vessel where the warp yarns extend across one weft yarn, the third region having a third region side first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a third region side second portion on one side of the artificial blood vessel; melting and solidifying the multifilament yarns on the surfaces of the second region side first portion and the third region side first portion by contacting a heating medium with the surface of the substrate that becomes the outer surface of the artificial blood vessel, or forming a surface covering the second region side first portion and the third region side first portion by coating the surfaces of the second region side first portion and the third region side first portion with a resin layer. The process includes: a process of covering a portion of multifilament yarn; a process of processing the substrate into a tubular shape to form a tubular body; a process of housing the tubular body in a housing member having a compression element, and applying pressure to the tubular body radially inward in a point-like manner using the compression element disposed between the inner surface of the housing member and the outer side of the tubular body; and a process of heating the compression element while the tubular body is under point-like radial inward pressure, deforming the surface of the covering portion into a shape under pressure, wherein the covering portion extends in the weft direction in such a way that it covers at least a portion of the surface of the warp yarn disposed between a pair of second region side first portions in the weft direction and the surface of the warp yarn disposed between a pair of third region side first portions in the weft direction, and the covering portion is configured to be able to move radially relative to the surface of the warp yarn disposed between a pair of second region side first portions in the weft direction and the surface of the warp yarn disposed between a pair of third region side first portions in the weft direction, according to the movement of the artificial blood vessel.

[0007] The invention provides that the artificial blood vessel and the method for manufacturing the artificial blood vessel according to the invention can maintain flexibility and improve resistance to blood leakage. Attached Figure Description

[0008] Figure 1 is a side view of an artificial blood vessel according to an embodiment of the present invention.

[0009] Figure 2 is a magnified view of a portion of region II in Figure 1.

[0010] Figure 3 is a fabric structure diagram showing an example of the braided structure of the substrate used for the artificial blood vessel in Figure 1.

[0011] Figure 4 is a schematic diagram of the substrate cross-section obtained by cutting the substrate along line IV-IV in Figure 3.

[0012] Figure 5 is a schematic diagram of the substrate cross-section obtained by cutting the substrate along the VV line in Figure 3.

[0013] Figure 6A is a 30x SEM image of the surface of the artificial blood vessel of this embodiment, taken radially.

[0014] Figure 6B is a 100x SEM image of the surface of the artificial blood vessel in Figure 6A, taken along an oblique direction.

[0015] Figure 6C is a 30x SEM image of the surface of an artificial blood vessel in another embodiment, taken radially.

[0016] Figure 7 is a schematic diagram showing the state in which the covering part of one warp yarn covers other warp yarns.

[0017] Figure 8 is a schematic diagram of a portion cut along the extension direction of the weft yarn, which is set in the covering part of one warp yarn to cover other warp yarns.

[0018] Figure 9 is a schematic diagram showing the relative movement of the covering portion of a warp yarn and other warp yarns when a force is applied radially outward relative to the inner surface of the artificial blood vessel from the state shown in Figure 8.

[0019] Figure 10 is a photograph of the artificial blood vessel of this embodiment when visible light is transmitted through it.

[0020] Figure 11 is a schematic diagram showing the state in which a cylindrical body is arranged on the outside of the core material for forming the peaks and valleys of the artificial blood vessel, and the winding component is partially wound around the outside of the cylindrical body.

[0021] Figure 12 is a schematic diagram of the state in which a cylindrical body is arranged on the outside of the core material for forming, viewed from the axial direction.

[0022] Figure 13 is a diagram of an example of the structure of a cylindrical body arranged on the outside of the forming core material for pressurizing the cylindrical body and a housing component for housing the compression element.

[0023] Figure 14 is a schematic diagram showing the interior of the storage component. Detailed Implementation

[0024] Hereinafter, an artificial blood vessel according to one embodiment of the present invention will be described with reference to the accompanying drawings. Furthermore, the embodiments shown below are merely examples, and the artificial blood vessel of the present invention is not limited to these embodiments.

[0025] Furthermore, in this specification, "perpendicular to A" and similar expressions refer not only to a direction that is completely perpendicular to A, but also include and indicate a direction that is approximately perpendicular to A. Additionally, in this specification, "parallel to B" and similar expressions refer not only to a direction that is completely parallel to B, but also include and indicate a direction that is approximately parallel to B. Furthermore, in this specification, "C-shape" and similar expressions refer not only to a complete C-shape, but also include and indicate a shape that is visually reminiscent of a C-shape (approximately C-shaped).

[0026] Figure 1 is a side view of an artificial blood vessel according to an embodiment of the present invention. Figure 2 is a partially enlarged view of region II of the artificial blood vessel of Figure 1. Figure 3 is a fabric structure diagram showing an example of the braided structure of the substrate used for the artificial blood vessel of Figure 1.

[0027] Artificial blood vessels are used, for example, to replace unhealthy biological blood vessels or to bypass biological blood vessels. As shown in Figures 1 and 2, the artificial blood vessel VE of this embodiment has alternating peaks M and valleys V along its axis X (refer to Figure 1). With alternating peaks M and valleys V, the artificial blood vessel VE can be formed with flexibility, making it less prone to kinking when bent. Furthermore, for ease of explanation in this specification, the portion of the artificial blood vessel VE extending radially from the midpoint between the top Mt of the peak M (refer to Figure 2) and the bottom Vb of the valley V (refer to Figure 2) to the radially outer side (upper side in Figure 2) is referred to as the peak M, and the portion extending radially from the midpoint between the top Mt of the peak M and the bottom Vb of the valley V to the radially inner side (lower side in Figure 2) is referred to as the valley V. In this embodiment, the artificial blood vessel VE is formed as a cylinder with the peaks M and valleys V spirally formed; however, the artificial blood vessel may also lack peaks M and valleys V.

[0028] The diameter of an artificial blood vessel (VE) can be varied depending on the site of application and is not particularly limited. For example, an artificial blood vessel (VE) can be a large-diameter vessel with an inner diameter of 10mm or more (used for aortas in the chest and abdomen), a medium-diameter vessel with an inner diameter of 6mm or 8mm (used for arteries in the lower limbs, neck, and axillary region), or a small-diameter vessel with an inner diameter of less than 6mm. The thickness of the artificial blood vessel (VE) is not particularly limited and can be appropriately varied depending on the inner diameter and length of the artificial blood vessel used. For example, the thickness of an artificial blood vessel (VE) can be set from 0.1mm to 2mm.

[0029] The length of the artificial blood vessel (VE) along its X-axis is not particularly limited and can be varied depending on the site of application. For example, the length of the artificial blood vessel (VE) along its X-axis can be set from 100mm to 1000mm. Furthermore, the artificial blood vessel (VE) is cut to the prescribed length by doctors or other personnel before transplantation to the desired site. Sometimes the artificial blood vessel (VE) is cut perpendicular to the X-axis, and sometimes it is cut at a prescribed angle relative to the X-axis.

[0030] When the artificial blood vessel VE has a peak M and a trough V, the number of peaks M (or troughs V) (the number of pleats) of the artificial blood vessel VE is not particularly limited, but can be appropriately set according to the desired twisting performance. 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 set to 20 to 70 per 100 mm of length along the X-axis, preferably 25 to 35. In addition, the interval (spacing) along the X-axis between the top Mt of the peak M of the artificial blood vessel VE (refer to Figure 2) and the top Mt of the adjacent peak M is not particularly limited, but can be set to, for example, 10% to 30% of the outer diameter of the artificial blood vessel VE (the outer diameter of 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 Figure 2) is not particularly limited, but it can be set to, for example, 5% to 20% of the outer diameter of the artificial blood vessel VE, preferably 5% to 15%.

[0031] Furthermore, in this embodiment, the curvature of the top Mt of the peak M is smaller than the curvature of the bottom Vb of the valley V (in this embodiment, the radius of curvature of the top Mt of the peak M is larger than the radius of curvature of the bottom Vb of the valley V). Moreover, "the curvature of the top Mt of the peak M is smaller than the curvature of the bottom Vb of the valley V" means that the degree of curvature of the top Mt of the peak M along the X-axis is smaller than the degree of curvature of the bottom Vb of the valley V along the X-axis (the curvature of the peak M is gentler than the curvature of the valley V), and the peak M and valley V do not need to form a complete arc surface. When the curvature of the top Mt of the peak M is smaller than the curvature of the bottom Vb of the valley V, stress is concentrated in the valley V when an external force is applied to the artificial blood vessel VE, therefore the artificial blood vessel VE is prone to curvature starting from the valley V. The curvature of the peak M and valley V is not particularly limited. For example, the radius of curvature of the top Mt of the peak M can be set to 5% to 8% of the diameter of the artificial blood vessel VE (and is greater than the radius of curvature of the bottom Vb of the trough V). Furthermore, the radius of curvature of the bottom Vb of the trough V can be set to 2% to 3% of the diameter of the artificial blood vessel VE (and is less than the radius of curvature of the top Mt of the peak M). By making the artificial blood vessel VE easily bendable and preventing it from easily returning to its original shape after bending, the load on the connection points between the artificial blood vessel VE and blood vessels can be reduced.

[0032] Furthermore, the curved portion of the top Mt of the peak M and the curved portion of the bottom Vb of the valley V can be connected via the planar portion PL (refer to Figure 2). This further improves flexibility and resistance to kinking compared to directly connecting the curved portions. Additionally, the angle between the planar portion PL1 on one side and the planar portion PL2 on the other side can be set to 20° to 40°, preferably 30°. The angle θ between the planar portion PL1 on one side and the planar portion PL2 on the other side can be appropriately set according to the diameter of the artificial blood vessel, the height of the peak, the height of the valley, and the spacing.

[0033] Next, the structure of the substrate constituting the artificial blood vessel VE will be described.

[0034] The artificial blood vessel VE of this embodiment has a prescribed weave structure formed by warp yarns 1 and weft yarns 2. In this embodiment, the artificial blood vessel VE has weft yarns 2 and warp yarns 1 composed of multifilament yarns. In this embodiment, at least the warp yarns 1 of the warp yarns 1 and weft yarns 2 constituting the artificial blood vessel VE are composed of multifilament yarns comprising multiple monofilament yarns. Furthermore, the weft yarns 2 may be composed of multifilament yarns or monofilament yarns. The prescribed weave structure of the artificial blood vessel VE will be described below.

[0035] In this embodiment, as shown in FIG3, the artificial blood vessel VE has warp yarns 1a-1l (hereinafter collectively referred to as warp yarns 1) extending along the X-axis direction (vertical direction in FIG3) and weft yarns 2a-2l (hereinafter collectively referred to as weft yarns 2) extending along the circumferential direction of the artificial blood vessel VE (horizontal direction in FIG3). More specifically, as shown in FIG3, the artificial blood vessel VE has multiple warp yarns 1a-1l and multiple weft yarns 2a-2l, and has a weaving structure in which the warp yarns 1 and weft yarns 2 are interlaced. Furthermore, in FIG3, the warp yarns 1 extend in the vertical direction, and the direction of extension of the warp yarns 1 (the X-axis direction of the artificial blood vessel VE) is referred to as D1. In addition, in FIG3, the weft yarns 2 extend in the horizontal direction, and the direction of extension of the weft yarns 2 (the circumferential direction of the artificial blood vessel VE) is referred to as D2. In FIG3, the portion of the warp yarns 1 exposed to the outer surface (surface) of the artificial blood vessel VE is shown in black (dotted portion), and the portion of the weft yarns 2 exposed to the outer surface of the artificial blood vessel VE is shown in white. Furthermore, there are no particular limitations on the looms used to manufacture VE artificial blood vessels.

[0036] As described below, in this embodiment, the warp yarn 1 has portions R21 and R31 extending across multiple weft yarns 2 (see Figures 3 and 5). Specifically, as shown in Figure 3, the warp yarn 1 has portions R21 and R31 extending across multiple weft yarns 2 and portions R1, R22, and R32 extending across a single weft yarn 2. Furthermore, the braiding structure of the artificial blood vessel VE is not necessarily limited to the braiding structure shown in Figure 3, and may have other braiding structures.

[0037] In this embodiment, as shown in FIG3, the artificial blood vessel VE has a first region R1 formed by warp yarns 1 and weft yarns 2 woven in a plain weave. Furthermore, the artificial blood vessel VE has a second region R2 on one side (in this embodiment, the outer surface of the artificial blood vessel VE). The second region R2 has a first portion R21 on the second region side where the warp yarns 1 extend across multiple weft yarns 2 (the portion extending across multiple weft yarns 2) and a second portion R22 on the second region side where the warp yarns 1 extend across one weft yarn 2 (the portion extending across one weft yarn 2). Moreover, the artificial blood vessel VE has a third region R3 on one side (in this embodiment, the outer surface of the artificial blood vessel VE). The third region R3 has a first portion R31 on the third region side where the warp yarns 1 extend across multiple weft yarns 2 (the portion extending across multiple weft yarns 2) and a second portion R32 on the third region side where the warp yarns 1 extend across one weft yarn 2 (the portion extending across one weft yarn 2). As shown in Figure 3, the first region R1, the second region R2, and the third region R3 are alternately formed in the extension direction D2 of the weft yarn 2. 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 yarn 2. The first part R21 on the second region side is adjacent to the second part R32 on the third region side in the extension direction D2 of the weft yarn 2, and the second part R22 on the second region side is adjacent to the first part R31 on the third region side in the extension direction D2 of the weft yarn 2. When the artificial blood vessel VE of this embodiment has the above structure, as described later, the warp yarn 1, which is made of multifilament yarn and extends longer without restraint in the first part R21 on the second region side or the first part R31 on the third region side, extends into the first region R1 woven with plain weave. Through the three-dimensional structure of this warp yarn 1, when blood seeps out from the fiber gaps generated in the first region R1 woven with plain weave, blood leakage can be suppressed, and blood is retained within the three-dimensional structure. By allowing blood to coagulate under a controlled state, resistance to blood leakage can be improved. The structure and weaving of each part of the artificial blood vessel (VE) are described below.

[0038] Warp 1 is a fiber that extends in one direction among the fibers constituting the artificial blood vessel VE. In this embodiment, warp 1 is a fiber that extends along the length direction (axis X direction) of the artificial blood vessel VE. Warp 1 is made of a material that can be applied to a fabric artificial blood vessel composed of a woven structure of fibers. The material of warp 1 is not particularly limited as long as it can be applied to fabric artificial blood vessels. For example, the material of warp 1 can be polyester, polytetrafluoroethylene, polyamide, etc. In addition, the material of warp 1 can also be a composite material, which is composed of two or more applicable materials with different properties such as melting point and elongation. For example, the material of warp 1 can be a synthetic fiber such as polyethylene terephthalate (PET) and polypropylene terephthalate (PTT) that are compounded during the spinning stage to form a long fiber with a helical crimp. For example, when a composite material consisting of two materials with different melting points and elongation rates, having a spiral curl, is used as the material for warp 1, the three-dimensional structure composed of warp 1, as described below, is easily extended in the extension direction D2 of weft 2, further improving the blood retention performance and enhancing blood leakage resistance.

[0039] In this embodiment, the warp yarn 1 is composed of multifilament yarn. Regarding the fineness of the warp yarn 1, for example, the single filament fineness of the warp yarn 1 can be set to 0.25 dtex to 2.50 dtex, preferably 0.50 dtex to 2.00 dtex, and the total fineness of the warp yarn 1 can be set to 2 dtex to 2500 dtex, preferably 6 dtex to 1600 dtex, more preferably 10 dtex to 540 dtex, and even more preferably 30 dtex to 200 dtex. By setting the single filament fineness and the total fineness of the warp yarn 1 to the above ranges, the warp yarns 1 in the second region R2 and the third region R3 can extend well toward the first region R1. Therefore, when blood seeps out from the gap in the first region R1, blood leakage can be suppressed by the warp yarns 1 in the second region R2 and the third region R3. The blood is held by the three-dimensional structure of the warp yarn 1, and the blood coagulates in the held state, thereby improving blood leakage resistance. Furthermore, "monofilament fineness" refers to the fineness of each single fiber constituting the warp yarn 1, and "total fineness" is the product of the monofilament fineness and the number of single fibers constituting the warp yarn 1. In addition, the number of single fibers constituting a single warp yarn (hereinafter referred to as the number of single fibers) is not particularly limited. However, for example, as described below, when the total number of single fibers in the warp yarn 1 is more than 1.5 times the number of single fibers in each 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 single fibers in each warp yarn 1 can be set to 8 to 1000, preferably 12 to 800, more preferably 20 to 270, and even more preferably 60 to 100. Furthermore, as described below, when the number of single fibers in each warp yarn 1 is 0.8 to 1.2 times the number of single fibers in each weft yarn 2, and the number of warp yarns 1 that cross multiple weft yarns 2 in the second region R2 is two or more, the number of single fibers in each warp yarn 1 can be set to 4 to 500, preferably 6 to 400, more preferably 10 to 135, and even more preferably 30 to 50.

[0040] The weft yarn 2 is a fiber that extends in the direction intersecting with the warp yarn 1 among the fibers constituting the artificial blood vessel VE. In this embodiment, the weft yarn 2 is a fiber that extends circumferentially in the artificial blood vessel VE. The weft yarn 2 is made of a material that can be applied to a fabric artificial blood vessel composed of a woven structure of fibers. The material of the weft yarn 2 is not particularly limited as long as it can be applied to fabric artificial blood vessels. For example, the material of the weft yarn 2 can be polyester, polytetrafluoroethylene, polyamide, etc.

[0041] Each weft yarn 2 can be a monofilament yarn or a multifilament yarn, but in this embodiment, the weft yarn 2 is composed of 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 monofilament fineness can be set to 15 dtex to 100 dtex, preferably 20 dtex to 75 dtex. Furthermore, when each of the weft yarns 2 is composed of multifilament yarn, for example, the monofilament fineness of the weft yarn 2 can be set to 0.25 dtex to 2.50 dtex, preferably 0.50 dtex to 2.00 dtex, and the total fineness of the weft yarn 2 can be set to 1 dtex to 1250 dtex, preferably 3 dtex to 800 dtex, more preferably 5 dtex to 270 dtex, and even more preferably 15 dtex to 100 dtex. Furthermore, "monofilament fineness" refers to the fineness of each single fiber (monofilament or multifilament) constituting the weft yarn 2, and "total fineness" is the product of the monofilament fineness and the number of single fibers constituting the weft yarn 2. In addition, when the weft yarn 2 is composed of multifilament yarn, the number of single fiber yarns constituting one weft yarn can be set to 4 to 500, preferably 6 to 400, more preferably 10 to 135, and even more preferably 30 to 50.

[0042] The first region R1 is the portion where warp yarns 1 and weft yarns 2 are woven in a plain weave. In Figure 3, the first region R1 is the area where warp yarns 1a, 1b, 1e, 1f, 1i, 1j and weft yarns 2 (weft yarns 2a~2l) intersect. In the first region R1 of the plain weave structure, as shown in Figure 4, the warp yarns 1 extend from one side of the artificial blood vessel VE (the outer surface of the artificial blood vessel VE, the upper side in Figure 4) to another side (the inner surface of the artificial blood vessel VE, the lower side in Figure 4) and from the other side to one side, crossing only one weft yarn 2 (not crossing multiple weft yarns 2). The first region R1 improves the strength of the artificial blood vessel VE, especially the tensile strength (in the X direction of the artificial blood vessel VE's axis). The first region R1 extends along the extension direction D1 of the warp yarns 1 in the X direction of the artificial blood vessel VE's axis. In addition, multiple first regions R1 are arranged separately from each other at predetermined intervals in the extension direction D2 of the weft yarns 2. In the extension direction D2 of the weft yarn 2, a second region R2 and a third region R3 are arranged between a first region R1 and another first region R1.

[0043] In this embodiment, in the first region R1, as shown in FIG3, two warp yarns 1a, 1b (warp yarns 1e, 1f or warp yarns 1i, 1j) and multiple weft yarns 2a~2l (and weft yarns not shown) are woven in a plain weave. The number of warp yarns 1 provided in one first region R1 can be set to 2 to 4, preferably 2 to 3, and more preferably 2. Furthermore, in this specification, when the warp yarn 1 is multifilament yarn, the term "number of warp yarns" does not refer to the number of individual fibers constituting the multifilament yarn, but rather to the number of warp yarns 1 that are composed of multiple individual fibers gathered together. By setting the number of warp yarns 1 to the above range, the range of the first region R1 that is not covered by the warp yarns 1 of the first part R21 on the second region side and the warp yarns 1 of the first part R31 on the third region side can be reduced. Therefore, the first region R1 of the plain weave is easily covered three-dimensionally by the warp yarns 1 of the first portion R21 on the second region side and the warp yarns 1 of the first portion R31 on the third region side. When blood seeps out from the first region R1, the three-dimensional structure of the warp yarns 1 of the first portion R21 on the second region side and the warp yarns 1 of the first portion R31 on the third region side retains the blood, and the blood coagulates in the retained state, thus reducing the amount of blood leakage from the artificial blood vessel VE. In addition, 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 set to, for example, 0.2 to 0.4 (1 / 3 in this embodiment). By setting the ratio of the number of warp yarns 1 to the number of warp yarns in the first region R1 to the range mentioned above, the strength of the artificial blood vessel VE can be improved, and the amount of blood leakage from the artificial blood vessel VE can be reduced.

[0044] The second region R2 has a first portion R21 on the second region side where the warp yarn 1 crosses multiple weft yarns 2 and a second portion R22 on the second region side where the warp yarn 1 extends across one weft yarn 2. As shown in FIG3, the first portion R21 and the second portion R22 on the second region side are alternately arranged in the extension direction D1 of the warp yarn 1. By having the first portion R21 and the second portion R22 on the second region side of the second region side, the artificial blood vessel VE can be made more flexible compared to an artificial blood vessel VE that is entirely composed of plain weave tissue structure. Furthermore, the portion of the warp yarn 1c provided in the second region R2 can be composed of a single warp yarn or multiple warp yarns. The number of warp yarns 1 provided in the second region R2 can be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0045] The first portion R21 of the second region side is a portion woven in such a way that the warp yarn 1 crosses multiple weft yarns 2. In this embodiment, the warp yarns 1c, 1g, 1k, etc., cross multiple weft yarns 2. By having the warp yarn 1 cross multiple weft yarns 2 in the first portion R21 of the second region side, the artificial blood vessel VE becomes softer in this portion compared to a plain weave structure. In addition, when the warp yarn 1 of the first portion R21 of the second region side is composed of multifilament yarn, the two ends of the first portion R21 of the second region side in the extension direction D1 of the warp yarn 1 are bound by the weft yarns 2 of the second portion R22 of the second region side (see part P1 in Figure 3). In this case, the first portion R21 of the second region side of the warp yarn 1, composed of multifilament yarns bound at both ends, forms a three-dimensional structure in which the central portion of the warp yarn 1 extends in the extension direction D1 of the warp yarn 1 toward the extension direction D2 of the weft yarn 2 (in addition, this three-dimensional structure also extends in the left-right direction and the forward direction of the paper in Figure 3). That is, in the first portion R21 of the second region side of warp 1, the width of the central portion of warp 1 in the extension direction D1 is greater than the width of the end portion of warp 1 in the extension direction D1 (see Figure 10). Therefore, the first region R1 of the plain weave structure adjacent to the first portion R21 of the second region side in the extension direction D2 of weft 2 is partially covered by the multifilament yarn of the extended first portion R21 of the second region side. Through this three-dimensional structure of warp 1, when blood seeps out from the fiber gaps generated in the first region R1 woven with plain weave, the seeping blood is held in the gaps between the single fibers of the three-dimensional structure composed of multifilaments. As a result, the blood coagulates in the held state, which improves the resistance to blood leakage. In addition, in this embodiment, the second portion R32 of the third region side adjacent to the first portion R21 of the second region side in the extension direction D2 of weft 2 is also similarly partially covered by the multifilament yarn of the extended first portion R21 of the second region side. Therefore, the gap created in the second part R32 of the third region is also covered by the multifilament yarn of the first part R21 of the second region, making it difficult for blood in the artificial blood vessel VE to leak out to the outside.

[0046] In the first portion R21 of the second region side (from the moment the warp yarn 1 emerges from one side of the artificial blood vessel VE to the other side (the side shown in Figure 3), the number of weft yarns 2 crossed by the warp yarn 1 is not particularly limited, but can be set to, for example, 2 to 5, preferably 3 to 4, and more preferably 3 (as shown in Figure 3). By setting the number of weft yarns 2 crossed by the warp yarn 1 within the above range in the first portion R21 of the second region side, it is easy to extend the multifilament yarn of the warp yarn 1 in the extension direction D2 of the weft yarn 2, and the artificial blood vessel VE can be maintained at the specified strength.

[0047] The first part R21 of the second region side only needs to have a portion where the warp yarn 1 crosses multiple weft yarns 2, and there is no particular limitation on the number of warp yarns 1 constituting the first part R21 of the second region side. For example, the first part R21 of the second region side (second region R2) can be composed of multiple (2) warp yarns (each warp yarn 1c, 1g, 1k is composed of multiple warp yarns). Alternatively, the first part R21 of the second region side (second region R2) can also have at least one warp yarn 1 that extends across (only) one weft yarn 2 and at least one warp yarn 1 that crosses multiple weft yarns 2.

[0048] The second portion R22 on the second region side is a section woven in such a way that the warp yarn 1 crosses only one weft yarn 2 (from the warp yarn 1 emerging from one face of the artificial blood vessel VE to the other face, without crossing multiple weft yarns 2). The second portion R22 on the second region side is set to the same length as the first portion R21 on the second region side in the extension direction D1 of the warp yarn 1. That is, the number of weft yarns 2 in the first portion R21 on the second region side (3 in Figure 3) is equal to the number of weft yarns 2 in the second portion R22 on the second region side (3 in Figure 3).

[0049] The third region R3 has a first portion R31 on the third region side where the warp yarn 1 crosses multiple weft yarns 2, and a second portion R32 on the third region side where the warp yarn 1 extends across one weft yarn 2. As shown in Figure 3, the first portion R31 and the second portion R32 on the third region side are alternately arranged in the extension direction D1 of the warp yarn 1. By having the first portion R31 and the second portion R32 on the third region side in the third region R3, the artificial blood vessel VE can be made more flexible compared to an artificial blood vessel VE that is entirely composed of plain weave tissue. Furthermore, the portion of the warp yarn 1d provided in the third region R3 can be composed of a single warp yarn or multiple warp yarns. The number of warp yarns 1 provided in the third region R3 can be, for example, 1 to 4, preferably 2 to 3, and more preferably 2.

[0050] The first portion R31 on the third region side is a portion woven in such a way that the warp yarn 1 crosses multiple weft yarns 2. In this embodiment, the warp yarns 1d, 1h, 1l, etc., cross multiple weft yarns 2. By having the warp yarn 1 cross multiple weft yarns 2 in the first portion R31 on the third region side, the artificial blood vessel VE becomes softer in this portion compared to a plain weave structure. In addition, when the warp yarn 1 of the first portion R31 on the third region side is made of multifilament yarn, the two ends of the first portion R31 on the third region side are bound by the weft yarns 2 of the second portion R32 on the third region side (see part P2 in Figure 3) in the extension direction D1 of the warp yarn 1. In this case, the first portion R31 on the third region side of the warp yarn 1, which is made of multifilament yarn with bound ends, forms a three-dimensional structure in which the central part of the extension direction D1 of the warp yarn 1 extends toward the extension direction D2 of the weft yarn 2. That is, in the first portion R31 of the third region side of warp 1, the width of the central portion of warp 1 in the extension direction D1 is greater than the width of the end portion of warp 1 in the extension direction D1 (see Figure 10). Therefore, the first region R1 of the plain weave structure adjacent to the first portion R31 of the third region side in the extension direction D2 of weft 2 is partially covered by the multifilament yarn of the extended first portion R31 of the third region side. Through this three-dimensional structure of warp 1, when blood seeps out from the fiber gaps generated in the first region R1 woven with plain weave, the seeping blood is held in the gaps between the single fibers of the three-dimensional structure composed of multifilaments. As a result, the blood coagulates in the held state, which improves the resistance to blood leakage. In addition, in this embodiment, the second portion R22 of the second region side adjacent to the first portion R31 of the third region side in the extension direction D2 of weft 2 is also similarly partially covered by the multifilament yarn of the extended first portion R31 of the third region side. Therefore, the gap created in the second part R22 on the second region side is also covered by the multifilament yarn in the first part R31 on the third region side, making it difficult for blood in the artificial blood vessel VE to leak out to the outside.

[0051] In the first part R31 of the third region side (from the moment the warp yarn 1 emerges from one side of the artificial blood vessel VE to the other side (the side shown in Figure 3), the number of weft yarns 2 crossed by the warp yarn 1 is not particularly limited, but can be set to, for example, 2 to 5, preferably 3 to 4, and more preferably 3 (as shown in Figure 3). By setting the number of weft yarns 2 crossed by the warp yarn 1 within the above range in the first part R31 of the third region side, it is easy to extend the multifilament yarn of the warp yarn 1 in the extension direction D2 of the weft yarn 2, and the artificial blood vessel VE can be maintained at the specified strength.

[0052] The first part R31 on the third region side only needs to have a portion where the warp yarn 1 crosses multiple weft yarns 2, and there is no particular limitation on the number of warp yarns 1 constituting the first part R31 on the third region side. For example, the first part R31 on the third region side (third region R3) can also be composed of multiple (2) warp yarns (each warp yarn 1d, 1h, 1l is composed of multiple warp yarns). In addition, the first part R31 on the third region side (third region R3) can also have at least one warp yarn 1 that extends across (only) one weft yarn 2 and at least one warp yarn 1 that crosses multiple weft yarns 2.

[0053] The second portion R32 on the third region side is a section woven in such a way that the warp yarn 1 crosses only one weft yarn 2 (from the warp yarn 1 emerging from one face of the artificial blood vessel VE to the other face, without crossing multiple weft yarns 2). The second portion R32 on the third region side is set to the same length as the first portion R31 on the third region side in the extension direction D1 of the warp yarn 1. That is, the number of weft yarns 2 in the first portion R31 on the third region side (3 in Figure 3) is equal to the number of weft yarns 2 in the second portion R32 on the third region side (3 in Figure 3).

[0054] As shown in Figures 5 and 6A-6C, the artificial blood vessel VE of this embodiment has: multiple covering portions C provided on the surface of the artificial blood vessel VE and covered with multifilament yarn in a planar manner; and non-covering portions UC provided on the surface of the artificial blood vessel VE between the multiple covering portions C and not covered by the covering portions C.

[0055] The covering portion C partially covers the surface of the artificial blood vessel VE with a single warp yarn or multiple monofilament yarns forming a weft yarn of a multifilament yarn. "Surface-like coverage of multifilament yarn" means that the covering portion C extends on the surface of the artificial blood vessel VE in the direction of extension of the multifilament yarn (the extension direction D1 of warp yarn 1) and in a direction perpendicular to the extension direction of the multifilament yarn (the extension direction D2 of weft yarn 2) by blocking the gaps between the multiple adjacent monofilament yarns forming the multifilament yarn on the surface of the artificial blood vessel VE. By providing the covering portion C, the gaps between the multiple monofilament yarns located radially inside the covering portion C are blocked on the surface of the artificial blood vessel VE, as will be explained in detail below. This improves the blood leakage resistance of the artificial blood vessel VE.

[0056] As shown in Figures 5 and 6A-6C, the covering portion C is disposed in multiple locations on the surface of the artificial blood vessel VE. Here, "multiple locations" means that when the surface of the artificial blood vessel VE is divided into multiple parts, the covering portion C is disposed in multiple parts. The covering portions C can be distributed separately from each other in multiple locations (see Figure 6A), or they can be continuously distributed in multiple locations along the axial direction (the extension direction D1 of the warp yarn 1) and / or the circumferential direction (the extension direction D2 of the weft yarn 2) of the artificial blood vessel VE (non-covering portions UC are distributed. See Figure 6C). Furthermore, the covering portions C are not regularly dispersed; sometimes they have locally concentrated areas and non-concentrated areas.

[0057] As shown in Figures 6A-6C, the uncovered portion UC is the portion of the artificial blood vessel VE that remains relative to the covered portion C on its surface and is not covered by the covered portion C. As shown in Figures 6A-6C, the uncovered portion UC is disposed between the covered portions C located in multiple places. For example, the uncovered portion UC is disposed between the covered portions C in the axial direction (the extension direction D1 of the warp yarn 1) and / or the circumferential direction (the extension direction D2 of the weft yarn 2) of the artificial blood vessel VE. The uncovered portion UC's placement between the covered portions C on the surface of the artificial blood vessel VE helps maintain the flexibility of the artificial blood vessel VE, as will be described in detail below. In this embodiment, the multifilament yarns of the warp yarn 1 and weft yarn 2 in the region of the uncovered portion UC are exposed on the surface of the artificial blood vessel VE while maintaining the gap between adjacent monofilament yarns (see Figures 6A and 6B).

[0058] As described above, in this embodiment, the artificial blood vessel VE has: multiple covering portions C, each having multiple multifilament yarns planarly covered on the surface of the artificial blood vessel VE; and non-covering portions UC, located between the multiple covering portions C and not covered by the covering portions C, on the surface of the artificial blood vessel VE. In this case, as described below, the transmittance of visible light can be reduced by partially covering the covering portions C. For example, the transmittance of visible light of the artificial blood vessel VE can easily be set to a range of 1.5% to 4%, easily balancing the flexibility and blood leakage resistance of the artificial blood vessel VE.

[0059] In this embodiment, as shown in FIG5, the artificial blood vessel VE has an inner braided portion IW on the radially inner side of the artificial blood vessel VE (lower side of FIG5) relative to the covering portion C. Multiple monofiber yarns of the multifilament yarn in the inner braided portion IW extend in a separated state. The inner braided portion IW constitutes part of the braided structure of the artificial blood vessel VE, and the multiple monofiber yarns are covered by the covering portion C in a separated state with gaps between them. The multiple monofiber yarns of the inner braided portion IW are schematically shown in FIG5, extending in a bundle-like manner with multiple adjacent yarns in the radial direction (vertical direction in FIG5) of the artificial blood vessel VE and multiple adjacent yarns in the extension direction D2 of the weft yarn 2 (depth direction of the paper in FIG5). Furthermore, in FIG6A and FIG6C, the inner braided portion IW is covered by the covering portion C and is not visible, but it is located in the depth direction of the paper relative to the covering portion C. The structure of the inner braided portion IW is not particularly limited as long as multiple monofiber yarns extend radially inside the artificial blood vessel VE relative to the covering portion C in a mutually separated state. In this embodiment, the inner braided portion IW has a structure in which the multifilament yarns in the region corresponding to the first portion R21 (and the first portion R31) of the second region side extend in the extension direction D2 of the weft yarn 2, and the multiple monofiber yarns constituting the multifilament yarns of the inner braided portion IW extend along the extension direction D1 of the warp yarn 1 in a mutually separated state. Furthermore, in this embodiment, as shown in FIG5, the warp yarn 1 has a covering portion C, which is a planar resin layer on the surface side of the artificial blood vessel VE, and an inner braided portion IW, which is a multifilament layer located radially inside the covering layer C, in the region corresponding to the first portion R21 (and the first portion R31) of the second region side.

[0060] An inner braided section (IW) is provided radially inside the covering section C. Multiple monofilament yarns extend separately within the radially inner side of the planar covering section C, with gaps between them. Therefore, the inner braided section (IW), composed of multifilament yarns covered by the covering section C, extends while maintaining a specified degree of flexibility. Thus, even with the planar covering section C, the overall flexibility of the artificial blood vessel (VE) is not easily compromised, achieving a balance between flexibility and blood leakage resistance. Furthermore, by having the inner braided section (IW), the inner structure of the artificial blood vessel can maintain its braided structure, inhibiting the invasiveness of damaging cells.

[0061] Furthermore, preferably, the covering portion C and the non-covering portion UC are alternately arranged on a portion of the surface of the artificial blood vessel VE in the axial direction (the extension direction of the warp yarn 1, D1) and / or the circumferential direction (the extension direction of the weft yarn 2, D2) of the artificial blood vessel VE. In this case, the covering portion C and the non-covering portion UC are evenly arranged in the axial and / or circumferential directions of the artificial blood vessel VE. Therefore, the flexibility and blood leakage resistance of the artificial blood vessel VE are evenly improved, and the situation of local hardening or easy local blood leakage of the artificial blood vessel VE is suppressed. In particular, when the covering portion C and the non-covering portion UC are alternately arranged in the axial direction of the artificial blood vessel VE, the artificial blood vessel VE is easy to bend, thereby facilitating the placement of the artificial blood vessel VE in the body. In addition, when the covering portion C and the non-covering portion UC are alternately arranged in the circumferential direction of the artificial blood vessel VE, the artificial blood vessel VE is easy to twist, and deformation (collapse) of the artificial blood vessel VE during twisting is suppressed. Therefore, for example, even if the artificial blood vessel VE is subjected to a torsional force due to thread tightening or the like when connected to an artificial heart-lung device, the collapse of the artificial blood vessel VE due to twisting can be suppressed. Therefore, the drawbacks caused by the torsion of the artificial blood vessel VE, such as blood clotting at the site of torsion and subsequent VE occlusion, are suppressed. In this embodiment, the covering portion C and the uncovered portion UC of the artificial blood vessel VE are alternately arranged in both the axial and circumferential directions. In this case, the flexibility and blood leakage resistance of the artificial blood vessel VE are uniformly improved throughout the entire artificial blood vessel VE.

[0062] The area where the covering portion C is provided is simply that the covering portion C is provided in multiple locations on the surface of the artificial blood vessel VE with a specified area, without any particular limitation. In this embodiment, as shown in Figures 5 and 7, the covering portion C is provided in the portions R21 and R31 of the warp yarn 1 that extend across multiple weft yarns 2 (in Figures 5 and 7, only the portion R21 extending across multiple weft yarns 2 is shown). More specifically, the covering portion C is provided in the portions corresponding to the first portion R21 on the second region side and the first portion R31 on the third region side. Furthermore, the covering portion C does not necessarily need to cover all the multiple single fiber yarns provided in the portions extending across multiple weft yarns 2 (the first portion R21 on the second region side and the first portion R31 on the third region side), as long as it covers most of the multiple single fiber yarns (there is no limitation, but for example, 50% or more, preferably 80% or more).

[0063] Furthermore, the structure of the covering portion C is not particularly limited as long as it covers the multifilament yarn in a planar manner. In this embodiment, the covering portion C is composed of a resin layer in a molten and solidified state of the multifilament yarn or coated on the surface of the multifilament yarn. "Molten and solidified state of the multifilament yarn" refers to a state in which a portion of the multifilament yarn constituting the warp yarn 1 and / or weft yarn 2 is temporarily melted by heating or the like, and then solidified to become a planar resin layer. In this case, the molten and solidified resin layer, i.e., the planar covering portion C, covers the surface of the artificial blood vessel VE with multiple single-fiber yarns in an unmelted state. In addition, "resin layer coated on the surface" refers to a resin layer formed by applying resin material in a planar manner to the multifilament yarn constituting the warp yarn 1 and / or weft yarn 2.

[0064] In this embodiment, the artificial blood vessel VE may also be configured to have the aforementioned first region R1, second region R2, and third region R3, and the visible light transmittance of the artificial blood vessel VE is 1.5% to 4%. In this case, as described below, the flexibility and blood leakage resistance of the artificial blood vessel VE can be balanced at a high level. By setting the lower limit of the visible light transmittance of the artificial blood vessel VE to 1.5%, more preferably to 2%, the flexibility of the artificial blood vessel VE can be improved. Furthermore, by setting the upper limit of the visible light transmittance of the artificial blood vessel VE to 4%, more preferably to 3%, the blood leakage resistance of the artificial blood vessel VE can be improved.

[0065] Here, the "visible light transmittance" of the artificial blood vessel VE refers to the ratio of light transmitted from one surface (inner surface) to the other surface (outer surface) of the artificial blood vessel VE when it is irradiated with visible light in the 380nm to 780nm wavelength range (see Figure 10). As a calculation method, for image data of the surface of the artificial blood vessel VE taken with a digital microscope at maximum light (e.g., 255 at 256 grayscale), the maximum light (255) is taken as the portion of light transmission, and the ratio of the number of pixels of the maximum light to the total number of pixels is calculated as the light transmittance. Furthermore, the visible light transmittance is the visible light transmittance of the artificial blood vessel VE in a specified region (e.g., a region including 10 warp yarns 1 and 10 weft yarns 2) having a specified area, including the peak M and the valley V. For example, the visible light transmittance in this specified region can be calculated at multiple locations, and their average value can be obtained. However, the visible light transmittance of the artificial blood vessel VE is not limited to the above range. Furthermore, if the visible light transmittance of the artificial blood vessel (VE) is within the aforementioned range, even if the local visible light transmittance deviates from the range of 1.5% to 4% in a portion of the artificial blood vessel (VE), it is acceptable as long as the average transmittance is within this range. Additionally, the visible light transmittance can be measured, for example, by cutting a portion of the artificial blood vessel (VE) as a sample and measuring it using a commercially available spectrophotometer. There are no particular limitations on the method for measuring visible light transmittance; for example, the spectrophotometric transmittance can be measured at multiple locations (e.g., 10 locations) while the sample of the artificial blood vessel (VE) being measured is moved, and the result is calculated by the arithmetic mean of these multiple measurements.

[0066] The transmittance of visible light corresponds to the size of the gap generated in the intersection area of ​​the warp yarns 1 and weft yarns 2 in the braided structure of the artificial blood vessel VE. Normally, if a braided structure with a visible light transmittance in the range of 1.5% to 4% is formed, the artificial blood vessel becomes a tightly woven structure and becomes rigid. However, in this embodiment, based on the formation of a specific braided structure having the aforementioned first region R1, second region R2, and third region R3, when the visible light transmittance is 1.5% to 4%, as described below, it is possible to balance the flexibility and blood leakage resistance of the artificial blood vessel VE at a high level.

[0067] In this embodiment, as shown in FIG7, the covering portion C extends in the extension direction D2 of the weft yarn 2 such that it covers at least a portion of the surface of the warp yarn 1 disposed between a pair of second region-side first portions R21 in the extension direction D2 of the weft yarn 2. In this embodiment, the covering portion C is configured to cover at least a portion of other warp yarns 1d, 1e, 1f that are different from the warp yarn 1c that includes the second region-side first portion R21 where the covering portion C is disposed. More specifically, the covering portion C is configured to cover at least a portion of the warp yarns 1d, 1e, 1f of the first region R1 or the second region-side second portion R22. Furthermore, although not shown in FIG7, the covering portion C extends in the extension direction D2 of the weft yarn 2 such that it covers at least a portion of the surface of the warp yarn 1 disposed between a pair of third region-side first portions R31 in the extension direction D2 of the weft yarn 2. In this embodiment, the covering portion C is configured to cover at least a portion of other warp yarns that are different from the warp yarn that includes the third region-side first portion R31 where the covering portion C is disposed. More specifically, the covering portion C is configured to cover at least a portion of the warp yarns of the first region R1 or the second portion R32 on the third region side.

[0068] In this case, as shown in Figure 7, the covering portion C of one warp yarn 1c, 1g covers the other adjacent warp yarns (e.g., warp yarns 1d, 1e, 1f in the case of Figure 7) in the extension direction D2 of the weft yarn 2. This not only suppresses blood leakage from the gaps between the multifilament yarns of one warp yarn 1, but also suppresses blood leakage from the gaps between the multifilament yarns of other warp yarns 1 different from one warp yarn 1. Therefore, the blood leakage resistance of the artificial blood vessel VE is improved. Furthermore, the covering portion C is located on the radially outer surface of one warp yarn 1, which becomes the artificial blood vessel VE, while the multifilament yarns on the radially inner side are in a spread-out state. Therefore, the spread-out multifilament yarns of the warp yarn 1 with the covering portion C and other warp yarns 1 are opposite each other radially to the artificial blood vessel VE, suppressing mutual fixation (in addition, due to individual differences, temperature conditions, etc., local fixation may sometimes occur). Therefore, the covering portion C, relative to the surfaces of the warp yarns 1 disposed between a pair of second region-side first portions R21 in the weft yarn extension direction D2 and the surfaces of the warp yarns 1 disposed between a pair of third region-side first portions R31 in the weft yarn extension direction D2, can move radially relative to the artificial blood vessel VE according to the movement of the artificial blood vessel VE. Specifically, as shown in FIG8, the covering portion C is formed on the surface of a warp yarn 1, and the multifilament yarns in a spread state between the surfaces of the warp yarn 1 with the covering portion C and other warp yarns 1 are in contact with each other. In this state, for example, when the artificial blood vessel VE is placed in the body, the pulsation of blood flow, etc., sometimes exerts a force radially outward relative to the inner side of the artificial blood vessel VE. In this case, the artificial blood vessel VE deforms in a way that increases in diameter. In this embodiment, since the warp yarn 1 is not fixed to the other warp yarns 1, the 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 weft yarn extension direction D2. Therefore, for example, in the case of expansion of the artificial blood vessel VE, blood leakage is suppressed by the covering portion C, and one warp 1 moves relative to the other warp 1, thereby allowing the artificial blood vessel VE to be flexibly deformed according to the blood flow within it. Thus, both the blood leakage resistance and flexibility of the artificial blood vessel VE can be achieved.

[0069] In this embodiment, as shown in Figures 2 and 6A, the artificial blood vessel is configured with alternating peaks M and valleys V along the X-axis. The transmittance of visible light in the valley V is lower than that in the peak M. In this case, the valley V has low transmittance and high resistance to blood leakage, but it tends to harden. However, the peak M ensures flexibility compared to the valley V, thus ensuring the overall flexibility of the artificial blood vessel VE. Furthermore, the artificial blood vessel VE has the aforementioned transmittance, thus ensuring overall resistance to blood leakage. However, the valley V has low transmittance (small gap), resulting in higher strength. Therefore, when a guidewire, catheter, or other medical device is inserted into the artificial blood vessel VE, the valley V in contact with the medical device has high strength, thus suppressing damage to the artificial blood vessel VE caused by contact with the medical device. Furthermore, the transmittance of visible light in the peak M and the valley V is not limited, but for example, the transmittance of visible light in the valley V can be set to 1% to 3%, and the transmittance of visible light in the peak M can be set to 2% to 4.5%. In addition, the transmittance of visible light in the valley V and the transmittance of visible light in the peak M can also be at the same level.

[0070] The following describes one example of the method for manufacturing the artificial blood vessel VE according to this embodiment. However, the following description is only an example, and the artificial blood vessel VE of the present invention is not limited to the following manufacturing method.

[0071] First, a substrate for an artificial blood vessel (VE) with the aforementioned braided structure is prepared. Specifically, as shown in Figure 3, the substrate comprises a first region R1 woven from warp yarns 1 and weft yarns 2 in a plain weave, a second region R2 having a first portion R21 on a second region side and a second portion R22 on a second region side, and a third region R3 having a first portion R31 on a third region side and a second portion R32 on a third region side. At this point, the substrate is sheet-like rather than tubular.

[0072] Next, a covering portion C is formed on the substrate. Specifically, a heating medium (not shown) is brought into contact with the surface of the substrate that forms the outer surface (surface) of the artificial blood vessel VE, causing a portion of the substrate (a portion of the multifilament yarn) to melt, and the molten portion to cool and solidify. In the aforementioned substrate, the first portion R21 on the second region side and the first portion R31 on the third region side protrude towards the outer surface of the artificial blood vessel VE in the thickness direction of the substrate compared to other portions (e.g., the first region R1, the second portion R22 on the second region side, and the second portion R32 on the third region side). Therefore, the multifilament yarn on the surface of the first portion R21 on the second region side and the first portion R31 on the third region side melts first. By adjusting the temperature of the heating medium, heating time, etc., only the surface of the substrate can be melted. Specifically, only the surface portion of the multifilament yarn of the first portion R21 on the second region side and the first portion R31 on the third region side melts in the thickness direction of the substrate, forming the outer surface of the artificial blood vessel VE; the portion on the inner surface of the artificial blood vessel VE does not melt. Thus, a covering portion C is formed that covers the first portion R21 on the second region side and the first portion R31 on the third region side in a planar manner. In this case, the portion on the inner surface side of the artificial blood vessel VE in the multifilament yarn of the substrate is in a state where multiple single-fiber yarns are spread out. Thus, a substrate with a two-layer structure of covering portion C and inner braided portion IW is obtained. Since the inner side (inner braided portion IW) of the multifilament yarn of the first portion R21 on the second region side and the first portion R31 on the third region side is not melted, as shown in FIG7, when the covering portion C of warp yarns 1c and 1g covers the surface of warp yarns 1d, 1e and 1f disposed between the first portions R21 and R21 on the second region side of a pair of warp yarns 1c and 1g, the covering portion C (inner braided portion IW) is not fixed to the covered warp yarns 1d, 1e and 1f. Therefore, as described above, as shown in Figures 8 and 9, the covering portion C can move relative to the warp yarn 1 covered by the covering portion C in the radial and weft yarn 2 extension directions D2 of the artificial blood vessel VE according to the movement of the artificial blood vessel VE (e.g., the movement of the artificial blood vessel VE when expanding radially outward). In this way, in this embodiment, even if the artificial blood vessel VE moves, one warp yarn 1 with the covering portion C and the other warp yarns 1 covered by the covering portion C can move relative to each other and deform softly while maintaining high blood leakage resistance. Therefore, the artificial blood vessel VE of this embodiment can maintain flexibility while improving blood leakage resistance. Furthermore, instead of melting the substrate, a resin layer can be applied to the multifilament yarn on the surface of the substrate. When applying the resin layer to the surface of the multifilament yarn, instead of the aforementioned heating process of the substrate (the process of melting a portion of the multifilament yarn), the resin material can be applied to the surface of the multifilament yarn in a desired pattern using a known method to form the covering portion C on the substrate.

[0073] Next, the substrate is processed into a cylindrical shape to form a cylindrical body CY (see Figure 11). At this point, the peak M and valley V have not yet formed in the cylindrical body CY. The method for forming the cylindrical body CY can employ known methods for manufacturing cylindrical artificial blood vessels (artificial blood vessels without pleats) with a prescribed braided structure, and therefore description is omitted. Furthermore, the process of forming the cylindrical body CY can also be performed before the process of bringing the heating medium into contact with the substrate.

[0074] After the substrate is processed into a cylindrical shape to form a cylindrical body CY, as shown in FIG11, a peak M and a valley V are formed on the cylindrical body CY. Specifically, the cylindrical body CY is positioned on the outside of a molding core material 3 (see FIG11) having a protrusion 31 and a recess 32 corresponding to the peak M and the valley V. The molding core material 3 has a size and shape corresponding to an artificial blood vessel VE, which has a peak M and a valley V of the desired size and shape. In this embodiment, the molding core material 3 is configured to cover the cylindrical body CY on the outside. Preferably, the outer diameter of the protrusion 31 of the molding core material 3 is the same as or smaller than the inner diameter of the cylindrical body CY, but the outer diameter of the protrusion 31 may also be slightly larger than the inner diameter of the cylindrical body CY. In this embodiment, the molding core material 3 is rotatably supported on a support body (not shown) of a molding apparatus including the molding core material 3 about an axis X.

[0075] If the cylindrical body CY is positioned outside the forming core material 3, as shown in FIG11, with the cylindrical body CY positioned outside the forming core material 3, the winding member 4 is wound around a portion of the circumference of the cylindrical body CY along the recess 32 of the forming core material 3. The winding member 4 is a member used to press a portion of the cylindrical body CY positioned outside the forming core material 3 into the recess 32 of the forming core material 3, forming a portion corresponding to a valley V in the cylindrical body CY. The winding member 4 is not particularly limited as long as it can form a valley V in the cylindrical body CY. In this embodiment, it can be a wire with a size that can enter between a pair of protrusions 31 corresponding to a pair of peaks M. Furthermore, in this embodiment, the winding member 4 is pre-tensioned under tension (see FIG12), and the forming core material 3 is rotated about the axis X, thereby the winding member 4 is wound spirally around the outer periphery of the cylindrical body CY, thereby forming a valley V in the cylindrical body CY. Alternatively, the core material 3 for forming can be moved such that the winding member 4 is wound in a spiral shape around the core material 3 without rotating, thereby forming the valley V in the cylindrical body CY.

[0076] Next, pressure is applied radially inward to the cylindrical body CY in a dotted pattern. Specifically, the cylindrical body CY, which is positioned outside the forming core material 3 and wound with the winding member 4, is housed in the housing member 5 (see Figures 13 and 14). The housing member 5 has a compression element PR (indicated by dots in Figure 14) positioned between the inner surface of the housing member 5 and the outer surface of the cylindrical body CY. In this embodiment, the cylindrical body CY is pressed radially inward using the compression element PR. In this embodiment, the compression element PR is composed of multiple granular bodies. In this embodiment, the compression element PR is composed of multiple granular bodies, whereby the granular compression element PR contacts the warp yarns 1 and weft yarns 2 of the cylindrical body CY in a dotted pattern. In this case, compared to the case where a linear compression element (e.g., a linear compression element wound around the entire cylindrical body CY along the extension direction of the peak M (circumferential direction of the artificial blood vessel VE) contacts the cylindrical body CY in a linear pattern, force is applied uniformly to the warp yarns 1 and weft yarns 2. Therefore, it prevents the warp yarns 1 and weft yarns 2 from shifting due to the large local force applied when the compression element PR compresses the cylindrical body CY, thus preventing the local gap from increasing.

[0077] In this embodiment, as shown in FIG14, with the forming core material 3 and the cylindrical body CY wound with the winding member 4 housed in the housing component 5, a plurality of granular compression elements PR are filled in the gap between the cylindrical body CY and the inner surface of the housing component 5. In this embodiment, the housing component 5 is configured to reduce its internal volume. By reducing the internal volume, the compression elements PR press the cylindrical body CY radially inward. As a result, a force is applied radially inward to the first portion R21 on the second region side and the first portion R31 on the third region side of the warp yarn 1, which is composed of multifilament yarn. Therefore, the first portion R21 on the second region side and the first portion R31 on the third region side are pressed by the compression elements PR and closely adhered to the shape of the surface of the warp yarn 1 disposed radially inward relative to the covering portion C on the artificial blood vessel VE. This further improves the blood leakage resistance of the artificial blood vessel VE.

[0078] The material and size of the compression element PR are not particularly limited, as long as they can be constructed in a way that allows the cylindrical body CY to be pressed radially inward. For example, the compression element PR can be made of a metal material with specified rigidity and the ability to conduct heat.

[0079] Furthermore, the structure of the storage component 5 is not particularly limited as long as it can press the cylindrical body CY radially inward by the granular compression element PR. In this embodiment, as shown in FIG13, the storage component 5 includes a main body 51 formed into a cylindrical shape and a cover 52 configured to be screwed onto the end of the main body 51. By screwing the cover 52 onto the main body 51, the cover 52 moves relative to the main body 51 in the axial direction of the main body 51. If the cover 52 moves in the axial direction of the main body 51, the pressing body 53 is pressed along the axial direction of the main body 51 by the cover 52, and the internal volume of the main body 51 decreases. As a result, by pressing the granular compression element PR stored in the storage component 5, the cylindrical body CY is pressed radially inward by the compression element PR. In addition, the storage component may also have other structures. For example, instead of the cover 52 of the storage component, a pressing component such as a hammer may be used to press the cylindrical body CY. Specifically, with granular compression elements PR arranged around the cylindrical body CY inside the housing component, a load can be applied to the compression elements PR from the outside of the housing component using a pressing component such as a hammer, thereby pressing the cylindrical body CY radially inward.

[0080] Next, the compression element PR is heated while the cylindrical body CY is compressed within the housing component 5 (see Figure 14). In this embodiment, the compression element PR is heated by placing the housing component 5 inside a heating furnace. Thus, the cylindrical body CY is heated by heat transfer from the compression element PR. The cylindrical body CY is heated in a point-pressed state at the points of contact with the compression element PR (especially the portions of the first portion R21 on the second region side and the first portion R31 on the third region side), thereby deforming it in a way that closely adheres to the surface shape of the warp yarn 1 covered by the covering portion C. Then, the cylindrical body CY, removed from the housing component 5, retains its shape under point-pressed conditions, completing the artificial blood vessel VE. In this embodiment, the cylindrical body CY is under point-pressed, thereby the covering portion C has a recess that is radially inward toward the artificial blood vessel VE (see Figure 6B). As described above, the recess reduces the gap between the artificial blood vessel VE and the other warp yarns 1 covered by the covering portion C, and the multiple recesses make the artificial blood vessel VE more flexible and easier to bend. Furthermore, the temperature of the heating process described above is not particularly limited, as long as the heating is performed to a temperature that deforms the covering portion C.

[0081] Alternatively, instead of placing the storage component 5 into the heating furnace, a compression element PR can be constructed using a conductive material, and heating can be achieved by flowing current through the compression element PR, thereby heating the cylindrical body CY.

[0082] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Furthermore, the above embodiments are mainly described based on an invention having the following structure.

[0083] (1) An artificial blood vessel having a weft yarn and a warp yarn composed of multifilament yarn, wherein the artificial blood vessel alternately has, in the extension direction of the weft yarn: a first region woven with the warp yarn and the weft yarn in a plain weave; a second region having a second region side first portion on one side of the artificial blood vessel where the warp yarn crosses multiple weft yarns and a second region side second portion where the warp yarn extends across one weft yarn; a third region having a third region side first portion on one side of the artificial blood vessel where the warp yarn crosses multiple weft yarns and a third region side second portion where the warp yarn extends across one weft yarn, the second region side first portion being adjacent to the third region side second portion in the extension direction of the weft yarn, the second region side second portion being adjacent to the third region side first portion in the extension direction of the weft yarn, the second region side first portion and the third region side first portion having a covering portion, the covering portion... The covering portion is composed of a resin layer that is either molten and solidified on the surface of the first portion of the second region side and the first portion of the third region side, or coated onto the surface of the multifilament yarn. The covering portion covers the multifilament yarn of the first portion of the second region side and the first portion of the third region side in a planar manner. The covering portion extends in the extension direction of the weft yarn in such a way that it covers at least a portion of the surface of the warp yarn disposed between a pair of first portions of the second region side in the extension direction of the weft yarn and the surface of the warp yarn disposed between a pair of first portions of the third region side in the extension direction of the weft yarn. The covering portion is configured to be able to move radially relative to the surface of the warp yarn disposed between a pair of first portions of the second region side in the extension direction of the weft yarn and the surface of the warp yarn disposed between a pair of first portions of the third region side in the extension direction of the weft yarn, according to the movement of the artificial blood vessel.

[0084] (2) The artificial blood vessel according to (1), wherein the artificial blood vessel has an inner braided portion on the radially inner side of the artificial blood vessel relative to the covering portion, wherein the multiple single fiber yarns of the multifilament yarn of the inner braided portion extend in a mutually separated state.

[0085] (3) The artificial blood vessel according to (1) or (2), wherein the covering portion has a recess that is recessed radially inward toward the artificial blood vessel.

[0086] (4) A method for manufacturing an artificial blood vessel having a weft yarn and a warp yarn composed of multifilament yarn, wherein the method comprises: a step of preparing a substrate, the substrate having alternating first, second, and third regions in the direction of extension of the weft yarn, the first region being woven with the warp yarn and the weft yarn in a plain weave structure, the second region having a second region on one side of the artificial blood vessel having a second region side first portion where the warp yarn crosses multiple weft yarns and a second region side second portion where the warp yarn extends across one weft yarn, the third region having a third region side first portion on one side of the artificial blood vessel having a third region side first portion where the warp yarn crosses multiple weft yarns and a third region side second portion where the warp yarn extends across one weft yarn; and a third region having a third region side first portion where the warp yarn crosses multiple weft yarns and a third region side second portion where the warp yarn extends across one weft yarn; and a method of melting and solidifying the multifilament yarn on the surface of the second region side first portion and the third region side first portion by contacting a heating medium with the surface of the substrate that becomes the outer surface of the artificial blood vessel, or by coating the surface of the second region side first portion and the third region side first portion with a resin layer to form a surface covering the second region side first portion and the third region side first portion. The process includes: a process of covering a portion of multifilament yarn; a process of processing the substrate into a tubular shape to form a tubular body; a process of housing the tubular body in a housing member having a compression element, and applying pressure to the tubular body radially inward in a point-like manner using the compression element disposed between the inner surface of the housing member and the outer side of the tubular body; and a process of heating the compression element while the tubular body is under point-like radial inward pressure, deforming the surface of the covering portion into a shape under pressure, wherein the covering portion extends in the weft direction in such a way that it covers at least a portion of the surface of the warp yarn disposed between a pair of second region side first portions in the weft direction and the surface of the warp yarn disposed between a pair of third region side first portions in the weft direction, and the covering portion is configured to be able to move radially relative to the surface of the warp yarn disposed between a pair of second region side first portions in the weft direction and the surface of the warp yarn disposed between a pair of third region side first portions in the weft direction, according to the movement of the artificial blood vessel.

[0087] Explanation of reference numerals in the attached drawings: 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 1k, 1l: warp yarns; 2, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 2j, 2k, 2l: weft yarns; 3: core material for forming; 31: protrusion; 32: concave part; 4: winding component; 5: storage component; 51: main body; 52: cover; 53: pressing body; C: covering part; CY: tubular body; D1: extension direction of warp yarns (axial direction of artificial blood vessel); D2: extension direction of weft yarns (circumferential direction of artificial blood vessel); IW: inner braided part; M: peak part; Mt: top of peak part; P1: portion of weft yarns at both ends of the first part on the second region side; P 2: The portion binding the weft yarns at both ends of the first part on the third region side; PL, PL1, PL2: Planar portion; PR: Compression element; R1: First region; R2: Second region; R21: First part on the second region side (the portion extending across multiple weft yarns); R22: Second part on the second region side (the portion extending across one weft yarn); R3: Third region; R31: First part on the third region side (the portion extending across multiple weft yarns); R32: Second part on the third region side (the portion extending across one weft yarn); UC: Non-covered portion; V: Valley; Vb: Bottom of the valley; VE: Artificial blood vessel; X: Axis of the artificial blood vessel; θ: Angle between the planar portion on one side and the planar portion on the other side.

Claims

1. An artificial blood vessel, comprising a weft yarn and a warp yarn composed of multifilament yarn, wherein, The artificial blood vessel alternately comprises: a first region woven with the warp and weft yarns in a plain weave; a second region having a first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a second portion on one side of the artificial blood vessel where the warp yarns extend across one weft yarn; and a third region having a first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a second portion on one side of the artificial blood vessel where the warp yarns extend across one weft yarn, the first portion on the second side of the second region being adjacent to the second portion on the third side of the second region in the direction of weft yarn extension, the second portion on the second side of the second region being adjacent to the first portion on the third side of the third region in the direction of weft yarn extension, the first portion on the second side of the second region and the first portion on the third side of the third region having a covering portion formed by the first portion on the second side of the second region. The covering portion is composed of a resin layer that is either melt-cured or coated on the surface of the multifilament yarn of the first portion of the third region side, and is planarly covering the multifilament yarn of the first portion of the second region side and the first portion of the third region side. The covering portion extends in the extension direction of the weft yarn in such a way that it covers at least a portion of the surface of the warp yarn disposed between a pair of first portions of the second region side in the extension direction of the weft yarn and the surface of the warp yarn disposed between a pair of first portions of the third region side in the extension direction of the weft yarn. The covering portion is configured to be able to move radially relative to the surface of the warp yarn disposed between a pair of first portions of the second region side in the extension direction of the weft yarn and the surface of the warp yarn disposed between a pair of first portions of the third region side in the extension direction of the weft yarn, according to the movement of the artificial blood vessel.

2. The artificial blood vessel according to claim 1, wherein, The artificial blood vessel has an inner braided portion on the radially inner side of the artificial blood vessel relative to the covering portion, wherein the multiple single fiber yarns of the multifilament yarn in the inner braided portion extend in a mutually separated state.

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

4. A method for manufacturing an artificial blood vessel having a weft yarn and a warp yarn composed of multifilament yarn, wherein, The method includes: a step of preparing a substrate, wherein the substrate alternately has a first region, a second region, and a third region in the extension direction of the weft yarns; the first region is woven with the warp yarns and the weft yarns in a plain weave; the second region has a first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a second portion on one side of the artificial blood vessel where the warp yarns extend across one weft yarn; the third region has a first portion on one side of the artificial blood vessel where the warp yarns cross multiple weft yarns and a second portion on one side of the artificial blood vessel where the warp yarns extend across one weft yarn; a step of melting and solidifying the multifilament yarns on the surfaces of the first portion on the second region side and the first portion on the third region side by contacting a heating medium with the surface of the substrate that becomes the outer surface of the artificial blood vessel, or forming multifilament yarns that cover the first portion on the second region side and the first portion on the third region side by coating the surfaces of the first portion on the second region side and the first portion on the third region side with a resin layer; and a step of processing the substrate into a tubular shape. The process of forming a cylindrical body includes: housing the cylindrical body in a housing component having a compression element, applying pressure to the cylindrical body radially inward using the compression element disposed between the inner surface of the housing component and the outer side of the cylindrical body in a point-like manner; and heating the compression element while the cylindrical body is being pressed radially inward in a point-like manner to deform the surface of the covering portion into a shape under pressure, wherein the covering portion extends in the weft direction in such a way that it covers at least a portion of the surface of the warp yarn disposed between a pair of first portions of the second region side in the weft direction and the surface of the warp yarn disposed between a pair of first portions of the third region side in the weft direction, and the covering portion is configured to be able to move radially relative to the surface of the warp yarn disposed between a pair of first portions of the second region side in the weft direction and the surface of the warp yarn disposed between a pair of first portions of the third region side in the weft direction, according to the movement of the artificial blood vessel.

Images