stent graft

Abstract

Provided are a stent graft and a skeleton for a stent graft that can improve adhesion to a living lumen. This stent graft (1) includes an end skeleton (23) disposed to protrude from a coating at one axial end of a tubular body part (11). The end skeleton is formed by bending a wire rod so that a mountain part (23a) and a valley part (23b) are repeated via a connection part (23c) in a circumferential direction, and the connection part has an inflection part that changes from a downward convex shape to an upward convex shape from the mountain part toward the valley part. Then, the inflection part is connected to the coating so that the protrusion length of the end skeleton in an expanded state is shorter than the protrusion length of the end skeleton in a contracted state.

Description

[Technical Field]

[0001] The present invention relates to a stent graft. To Regarding. [Background technology]

[0002] Conventionally, stent grafts have been known that are placed in narrowed or obstructed areas in biological lumens such as blood vessels, esophagus, bile duct, trachea, and ureter, and that expand the diameter of the diseased area to maintain the patency of the biological lumen (see, for example, Patent Document 1). Stent graft placement is a treatment method in which, for example, a groin is surgically incised to expose the blood vessel, a stent graft placement device is introduced into the blood vessel and delivered to the lesion site, and the stent graft is then released from the sheath and placed in close contact with the blood vessel wall. This has the advantage of being minimally invasive, as the incision is small and the burden on the patient is minimal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-516509 Summary of the Invention [Problem to be solved by the invention]

[0004] As disclosed in Patent Document 1, some stent grafts have an end skeleton arranged at the distal end (e.g., the proximal end) of the stent graft so as to protrude from the membrane in order to prevent the stent graft from shifting from the placement site in the biological lumen and to ensure accurate placement. However, in such stent grafts, wrinkles are likely to form in the membrane portion where the end skeleton is connected, which may reduce adhesion to the biological lumen.

[0005] In addition, some stent grafts have a framework sewn to a membrane. To properly secure the framework to the membrane, the more stitches there are, the better. However, the greater the number of stitches, the lower the flexibility and the lower the ability to conform to the body lumen, resulting in poor adhesion.

[0006] An object of the present invention is to provide a stent graft that can improve adhesion to a biological lumen. To The purpose is to provide. [Means for solving the problem]

[0007] The stent graft according to the present invention comprises: Using a delivery system A stent graft to be placed in a biological lumen, a cylindrical main body having a main body skeleton covered with a membrane; A film is disposed at one axial end of the main body so as to protrude from the film. , separate from the main body skeleton and of a different shape An end skeleton, Equipped with The end skeleton is formed by bending the wire material. Has a convex corner Mountain and peripheral side Has a convex corner The valley portions are formed so as to be repeated in the circumferential direction via the connecting portions, the connecting portion has an inflection portion that changes from a convex portion toward the peripheral side to a convex portion toward the central side from the peak portion toward the valley portion, and is bent in a substantially "S" shape as a whole together with the peak portion and the valley portion, The inflection portion changes from a convex toward the peripheral side to a convex toward the central side with an inflection point as a boundary, The inflection portion is attached to the membrane so that the protrusion length of the end skeleton in the expanded state is shorter than the protrusion length in the contracted state, and the portion of the end skeleton from the protruding portion on the peripheral side to the mountain portion can move relative to the membrane. sewing And 、 The portion of the end skeleton protruding from the coating is used to engage with a hook of the delivery system. . [Effects of the Invention]

[0010] According to the present invention, it is possible to improve the adhesion to the biological lumen. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the appearance of a stent graft. [Figure 2] FIG. 2 is a diagram schematically illustrating the state in which the stent graft is placed. [Figure 3] FIG. 3 is an enlarged view of the bare portion. [Figure 4] 4A and 4B are diagrams schematically showing the shape and length of the end skeleton in the expanded state and the contracted state, respectively. [Figure 5] 5A and 5B are diagrams schematically showing a fixing mode of the second main body skeleton. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, as an example of the present invention, a stent graft 1 is described which is used to treat an occlusion (stenosis) by radially expanding a diseased area (e.g., an aortic aneurysm B) in the descending aorta A (see Figure 2) outward.

[0013] Fig. 1 is a diagram showing the appearance of a stent graft 1. Fig. 2 is a diagram showing the stent graft 1 in an indwelling state.

[0014] As shown in Figure 1, the stent graft 1 has a main body portion 11 and a bare portion 12 disposed at the central end of the main body portion 11. The main body portion 11 has a tubular shape that defines a blood flow path, and has a straight trunk portion 11a and a seal portion 11b connected to the central end of the trunk portion 11a. The stent graft 1 is placed in the descending aorta A so that the bare portion 12 is located upstream (toward the heart) in the direction of blood flow (see Figure 2).

[0015] The stent graft 1 is composed of a framework 20 and a membrane 30 . The framework 20 is a reinforcing member for maintaining the expanded state of the stent graft 1. The framework 20 is formed to be self-expandable in a radial direction substantially perpendicular to the axial direction, from a contracted state in which it contracts inward to an expanded state in which it expands outward.

[0016] The skeleton 20 includes a first main body skeleton 21 arranged in the trunk portion 11a, a second main body skeleton 22 arranged in the seal portion 11b, and an end portion skeleton 23 arranged in the bare portion 12. The first main body skeleton 21 and the second main body skeleton 22 are arranged on the circumferential surface of the coating 30. For example, the peripheral side portion of the end portion skeleton 23 is fixed to the coating 30, and a central side portion is exposed from the coating 30. Note that a fixing pin may be provided so as to protrude radially outward near the peak 23a (bent portion on the central side) of the end skeleton 23. This allows the fixing pin to bite into the blood vessel wall, preventing the stent graft 1 from shifting position.

[0017] The first main body skeleton 21 and the second main body skeleton 22 are each formed as a spiral skeleton, for example, by spirally winding a single metal wire while bending it in a zigzag (Z-shape) so that peaks 21a, 22a (bent portions on the central side) and valleys 21b, 22b (bent portions on the peripheral side) are alternately formed. The first main body skeleton 21 and the second main body skeleton 22 are each spirally wound a plurality of times and arranged at predetermined intervals along their respective axial directions (extension directions of the stent graft 1). In this embodiment, the bending angles of the bent portions (peaks 21a, 22a and valleys 21b, 22b) in the first main body skeleton 21 and the second main body skeleton 22 are set to be the same, and the lengths of the sides sandwiching the bent portions are set to be different from each other. The bending angles of the bent portions and the lengths of the sides sandwiching the bent portions are merely examples and are not limited thereto, and can be changed as appropriate, and the bending angles may be different or the lengths of the sides may be the same. Furthermore, the ends of the metal wires constituting the first main body skeleton 21 and the second main body skeleton 22 may be fixed by being sewn to the coating 30, or may be fixed by being crimped to other parts of the metal wires or to each other.

[0018] The end skeleton 23 is configured, for example, as a circular ring skeleton obtained by bending a single metal wire so that peaks 23a (bent portions on the central side) and valleys 23b (bent portions on the peripheral side) are repeatedly formed in the circumferential direction via connecting portions 23c. The end skeleton 23 may also be configured as a laser-cut circular ring skeleton formed by laser processing a metallic cylindrical member. The ends of the metal wire constituting the end skeleton 23 may be fixed by being sewn to the coating 30, or may be fixed by being crimped to other parts of the metal wire or to each other.

[0019] The cross-sectional areas of the wire rods forming the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23 may be the same or different. When the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23 are formed of round wire rods, the "cross-sectional area" may be read as "wire diameter." Furthermore, the cross-sectional area of ​​the first main body skeleton 21 arranged in the trunk portion 11a may be set smaller than the cross-sectional area of ​​the second main body skeleton 22 arranged in the seal portion 11b. This allows the outer diameter of the main body portion 11 in the contracted state to be further reduced, further improving the ease of storing the stent graft 1 in a sheath and the ease of releasing it from the sheath. Furthermore, as long as the expansion force of at least the sealing portion 11b ensures adhesion to the blood vessel wall, it is possible to prevent blood from flowing in (endoleak) from the upstream side (central side) in the blood flow direction. Therefore, the expansion force of the trunk portion 11a, which is located downstream (peripheral side) in the blood flow direction from the sealing portion 11b, may be smaller than the expansion force of the sealing portion 11b.

[0020] 3 and the like, connecting portion 23c connecting peak portion 23a and valley portion 23b is not linear, but has a characteristic shape such that the protrusion length in the expanded state of end skeleton 23 (see FIG. 4A) is shorter than the protrusion length in the contracted state (see FIG. 4B). Figures 4A and 4B are developments showing the shape and length of end skeleton 23, with Fig. 4A showing the expanded state and Fig. 4B showing the contracted state.

[0021] Specifically, connecting portion 23c has an inflection portion (a portion located near the central opening) that changes from a downward convex to an upward convex from peak portion 23a to valley portion 23b. Here, "changing from a downward convex to an upward convex from peak portion 23a to valley portion 23b" includes a case in which the slope of the contact point gradually decreases, passes through a slope of 0, and then gradually increases, as shown in Fig. 4A, as well as a case in which the slope increases by bending at the inflection point. Furthermore, connecting portion 23c may be entirely or partially inflected.

[0022] Furthermore, connecting portion 23c is bent, for example, together with peaks 23a and valleys 23b, into a generally "S" shape overall, and the length of connecting portion 23c is longer than the length when peaks 23a and valleys 23b are linearly connected. Note that the bent portion of connecting portion 23c of end skeleton 23 is sewn to membrane 30 so that the protruding length in the expanded state is shorter than the protruding length in the contracted state, a detailed description of which will be given later.

[0023] Furthermore, the first main body skeleton 21, the second main body skeleton 22 and the end skeleton 23 are arranged so that the peaks 21a, 22a, 23a and the valleys 21b, 22b, 23b are aligned on the axis of the stent graft 1. This improves the contractibility when contracting the stent graft 1, and improves the ease of storage in a sheath and release from the sheath.

[0024] Examples of materials for forming the framework 20 include known metals or metal alloys such as stainless steel, nickel-titanium alloy (nitinol), and titanium alloy. Alternatively, an alloy material having X-ray contrast properties may be used. In this case, the position of the stent graft 1 can be confirmed from outside the body. The framework 20 may also be formed from materials other than metals (for example, ceramics, resin, etc.).

[0025] The material of the wire forming the skeleton 20, the type of wire (for example, circular wire such as wire, or angular wire made by laser cutting), cross-sectional area (corresponding to the wire diameter in the case of round wire), the number of bends in the circumferential direction and the shape of the bends (the number of ridges and the shape of the ridges), and the wire spacing in the axial direction (amount of skeleton per unit length) are selected based on criteria such as the ability to be stored in a sheath, the ability to be released from the sheath, and the ability to be placed (corresponding to the expansion force) required for each stent graft 1 depending on the placement site.

[0026] The coating 30 is a membrane that forms a blood flow path. Examples of materials that can be used to form the coating 30 include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate. The thickness of the coating 30 is preferably, for example, 80 μm or less.

[0027] In this embodiment, the first main body skeleton 21 is disposed on the outer peripheral surface of the coating 30. As a result, when the stent graft 1 is placed, the first main body skeleton 21 disposed in the trunk portion 11a, which is the main portion of the stent graft 1, is embedded in the blood vessel wall, effectively preventing the stent graft 1 from shifting position.

[0028] Additionally, the second main body skeleton 22 is disposed on the inner circumferential surface of the membrane 30. This increases the adhesion of the seal portion 11b located on the central side to the blood vessel wall, thereby suppressing endoleak from the central side.

[0029] The end skeleton 23 is disposed with its central side exposed on the inner peripheral surface of the central side of the coating 30. The portion of the end skeleton 23 protruding from the coating 30 is used to engage with a hook of a delivery system (not shown) with a tip-opening mechanism when the stent graft 1 is placed using the delivery system, for example.

[0030] The arrangement of the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23 in the coating 30 is merely an example and is not limited thereto, and can be arbitrarily changed as appropriate. For example, the coating 30 may be arranged on the outer peripheral surface side and inner peripheral surface side of the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23 so as to sandwich the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23. Furthermore, the coating 30 may be arranged on the outer peripheral surface side of the first main body skeleton 21, the inner peripheral surface side of the second main body skeleton 22, or the inner peripheral surface side of the end portion skeleton 23.

[0031] In this embodiment, the framework 20 is sewn to the outer periphery of the membrane 30 with sutures 40 (for example, polyethylene or polyester threads).

[0032] Specifically, the peaks 21a and valleys 21b of the first main body skeleton 21 are sewn to the membrane 30. Only the peaks 22a of the second main body skeleton 22 are sewn to the membrane 30. This allows the area near the valleys 22b of the second main body skeleton 22 to move freely relative to the membrane 30, improving the flexibility of the sealing portion 11b and improving its ability to conform to the body lumen.

[0033] 5A and 5B, the end 22d of the second main body skeleton 22 is sewn to the membrane 30 at a portion other than the bent portion. Only the peaks 22a of the second main body skeleton 22 are fixed to the membrane 30, increasing the degree of freedom of the portion of the second main body skeleton 22 other than the peaks 22a relative to the membrane 30. If the end 22d of the second main body skeleton 22 were firmly fixed to the membrane 30, there would be no escape route for the force applied to the end 22d, and the degree of freedom of the entire second main body skeleton 22 relative to the membrane 30 might decrease. Therefore, in this embodiment, the bent portion of the end 22d of the second main body skeleton 22 is not fixed, but is fixed by sewing at a portion other than the bent portion.

[0034] Specifically, the tip of second main body skeleton 22 extends toward the position where valley portion 22b is likely to be located, and the portion bent toward peak portion 22a to have an R-shape constitutes end portion 22b. The vicinity of the R-shaped portion of end portion 22b (the periphery of the bent portion) is sewn. This prevents end portion 22d of second main body skeleton 22 from piercing the blood vessel wall and also prevents end portion 22d from slipping off from the sewn portion. 5B, the periphery of the end 22d of the second main body skeleton 22 may be covered with a patch 50. The patch 50 is made of, for example, the same material as the membrane 30 and is fixed to the membrane 30 by stitching. This reliably prevents the end 22d from coming loose from the stitched portion.

[0035] 5A and 5B show the central end of the second main body skeleton 22, but the same end treatment is also applied to the peripheral end. The same end treatment as that of the second main body skeleton 22 may also be applied to the end of the first main body skeleton 21. The patch 50 may be fixed by adhesion instead of by suturing. The patch 50 may also be formed of a heat-sealing film and fixed to the membrane 30 by heat welding.

[0036] The manner in which the first main body skeleton 21, the second main body skeleton 22, and the end portion skeleton 23 are sewn to the membrane 30 is merely an example and is not intended to be limiting, and can be arbitrarily modified as appropriate. For example, in addition to the peaks 21a and valleys 21b of the first main body skeleton 21, the connecting portions 21c connecting the peaks 21a and valleys 21b may be sewn to the membrane 30. Furthermore, in addition to the peaks 22a of the second main body skeleton 22, at least one of the valleys 22b and the connecting portions 22c may be sewn to the membrane 30.

[0037] The inflection portion of the connecting portion 23c of the end skeleton 23 is sewn to the membrane 30 so that the protrusion length in the expanded state is shorter than the protrusion length in the contracted state. Specifically, the approximate center of the inflection portion of the connecting portion 23c is sewn to the membrane 30, and the peak portion 23a side of the inflection portion is free to move relative to the membrane 30. As a result, the portion that was located at the open end of the membrane 30 in the expanded state (see FIG. 4A) protrudes from the membrane 30 in the contracted state (see FIG. 4B). In other words, the portion that protrudes from the membrane 30 in the contracted state is also located at the open end of the membrane 30 in the expanded state, and contributes to the expansion of the membrane 30. Therefore, during expansion, the length (amount of skeleton) of the end skeleton 23 located at the open end of the coating 30 in the bare portion 12 increases, and the portion at the open end of the coating 30 where the end skeleton 23 is not located becomes relatively small, allowing the coating 30 to expand appropriately, making it less likely to wrinkle and improving adhesion to the descending aorta A. Furthermore, the central end of the stent graft 1 can be reliably expanded and opened. In particular, by shaping the end skeleton 23 so that the curved portion of the connecting portion 23c extends along the opening end of the coating 30 in its expanded state, that is, by lengthening the portion with a small inclination, preferably a portion with an inclination of approximately 0, relative to the extension direction of the opening end of the coating 30, the coating 30 can be expanded more appropriately.

[0038] Furthermore, when the stent graft 1 is contracted, the tip portion (ridge portion 23a) of the end skeleton 23 protrudes a long distance from the coating 30, allowing for more appropriate engagement with the hook of the delivery system (not shown) of the tip-opening mechanism for placing the stent graft 1.

[0039] As described above, the stent graft 1 according to the embodiment is a stent graft to be placed in the descending aorta A (biological lumen), and comprises a tubular main body portion 11 formed by covering a first main body skeleton 21 and a second main body skeleton 22 (main body skeletons) with a coating 30, and an end skeleton 23 disposed at the central end (one axial end) of the main body portion 11 so as to protrude from the coating 30. The end skeleton 23 is formed by bending a wire material so that peaks 23a and valleys 23b are repeated in the circumferential direction via connecting portions 23c. Furthermore, the connecting portions 23c have an inflection portion that changes from a downwardly convex to an upwardly convex shape from the peaks 23a to the valleys 23b, and the inflection portion is connected to the coating 30 so that the protrusion length of the end skeleton 23 in an expanded state is shorter than the protrusion length in a contracted state. This ensures that, in the expanded state, the length (amount of skeleton) of the end skeleton 23 located near the opening of the coating 30 is as long as possible. Therefore, the portion of the open end of the coating 30 where the end skeleton 23 is not located is relatively small, and the coating 30 is expanded appropriately, making it less likely to wrinkle and improving adhesion to the descending aorta A.

[0040] Furthermore, the approximate center of the inflection portion of end skeleton 23 is connected to membrane 30. This allows peak 23a of connecting portion 23c to move freely relative to membrane 30, and while it is located at the open end of membrane 30 in the expanded state, it protrudes from membrane 30 in the contracted state. This allows membrane 30 to expand appropriately during expansion, and improves radial contractibility, making it easier to store in a sheath.

[0041] Furthermore, the first main body skeleton 21 and the second main body skeleton 22 (main body skeletons) are formed by bending wire rods so that the peaks 21a, 22a and valleys 21b, 22b are repeated in the circumferential direction, and the peaks 21a, 22a, 23a and valleys 21b, 22b, 23b of the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 are arranged so as to be aligned in the axial direction. This improves the contractibility when contracting the stent graft 1, and improves the ease of storage in a sheath and release from the sheath.

[0042] Additionally, the second main body skeleton 22 is sewn to the membrane 30 at the peaks 22a (portions other than the valleys 22b). This allows the second main body skeleton 22 near the valleys 22b to move freely relative to the membrane 30, improving the flexibility of the sealing portion 11b and improving its ability to conform to the body lumen.

[0043] Additionally, the second main body skeleton 22 is sewn to the inner periphery of the membrane 30. This increases the adhesion of the seal portion 11b located on the central side to the biological lumen wall, thereby suppressing endoleak from the central side.

[0044] Furthermore, the bent portion of the end 22d of the second main body skeleton 22 is not sewn to the membrane 30, but is sewn to the membrane 30 at a portion other than the bent portion. This allows the degree of freedom of the entire second main body skeleton 22 relative to the membrane 30 to be increased by not fixing the bent portion of the end 22d, thereby improving the flexibility of the stent graft 1 and improving its adhesion to the biological lumen wall.

[0045] The invention made by the inventor has been specifically described above based on an embodiment, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist thereof.

[0046] For example, in the embodiment, the bending angle of the skeleton 20 is set so that the first main body skeleton 21 and the second main body skeleton 22 of the main body portion 11 and the end skeleton 23 of the bare portion 12 have a predetermined expansion force, but all of the skeletons 21 to 23 do not have to have the predetermined expansion force.

[0047] Although the first main body skeleton 21 and the second main body skeleton 22 are spiral skeletons in which a single metal wire is bent in a zigzag shape and wound in a spiral, they may be configured, for example, as multiple ring skeletons spaced apart in the axial direction. Furthermore, the end skeleton 23 is configured as a ring skeleton in which a single metal wire is bent in a zigzag shape and extended in the circumferential direction, but they may be configured, for example, as a spirally wound skeleton.

[0048] The present invention is not limited to stent grafts 1 placed in the descending aorta A (see FIG. 2), but can also be applied to stent grafts placed in other biological lumens such as digestive lumens and other blood vessels. The end of the stent graft 1 downstream in the blood flow direction may be bifurcated or branched into two or more branches.

[0049] Furthermore, in the embodiment, the main body portion 11 will have a curved shape that follows the shape of the lumen after placement, but this is just one example and is not limited to this, and the main body portion 11 may have a straight cylindrical shape or a curved shape depending on the placement site.

[0050] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0051] The disclosures of the specifications, drawings and abstracts contained in Japanese patent applications No. 2020-035005 filed on March 2, 2020 and No. 2020-042584 filed on March 12, 2020 are incorporated herein by reference in their entirety. [Explanation of symbols]

[0052] 1. Stent graft 11 Main body 11a Torso 11b Seal part 12 Bear Club 20 Skeleton 21 First main body skeleton 22 Second main body skeleton 23 End skeleton 21a, 22a, 23a Mountain 21b, 22b, 23b Tanibe 21c, 22c, 23c connection part 22d end 30 membrane

Claims

1. A stent graft that is placed in a biological lumen using a delivery system, a cylindrical main body having a main body skeleton covered with a membrane; an end skeleton that is separate from the main body skeleton and has a different shape from the main body skeleton and is disposed at one axial end of the main body portion so as to protrude from the coating; Equipped with The end skeleton is formed by bending a wire rod so that a peak portion having a convex corner on the central side and a valley portion having a convex corner on the peripheral side are repeated in the circumferential direction via a connecting portion, the connecting portion has an inflection portion that changes from a convex portion toward the peripheral side to a convex portion toward the central side from the peak portion toward the valley portion, and is bent in a substantially "S" shape as a whole together with the peak portion and the valley portion, The inflection portion changes from a convex toward the peripheral side to a convex toward the central side with an inflection point as a boundary, the inflection portion is sewn to the membrane so that the protrusion length of the end skeleton in an expanded state is shorter than the protrusion length in a contracted state, and the portion of the end skeleton from the distally convex portion to the peak portion is movable relative to the membrane; A stent graft, wherein the portion of the end framework protruding from the coating is used for engaging with a hook of the delivery system.

2. The stent graft of claim 1 , wherein the distally convex portion and the proximally convex portion of the inflection portion extend along an open end of the coating in the expanded state.

3. The stent graft according to claim 2 , wherein a portion of the inflection portion closer to the distal side than the distally convex portion is sewn to the membrane.

4. The main body skeleton is formed by bending wire rods so that peaks and valleys are repeated in the circumferential direction, The stent graft according to claim 1 , wherein the main body framework and the end framework are arranged such that the peaks and valleys of each framework are aligned in the axial direction.

5. the main body skeleton includes a first main body skeleton and a second main body skeleton disposed closer to one end in the axial direction than the first main body skeleton, 5. A stent graft as claimed in any one of claims 1 to 4, wherein the second main body skeleton is formed by bending a wire material so that peaks and valleys are repeated in the circumferential direction, and is sewn to the membrane at portions other than the valleys.

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