WO2021177303A1 - Stent graft and skeleton for stent graft - Google Patents

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

Stent graft and skeleton for stent graft

The present invention relates to a stent graft and a skeleton for a stent graft.

Conventionally, a stent graft that is placed in a stenosis or an obstruction formed in a living lumen such as a blood vessel, esophagus, bile duct, trachea, or ureter, and expands the lesion site to maintain a patency of the living lumen is known. (See, for example, Patent Document 1).
In stent graft placement, for example, the groin is surgically incised to expose the blood vessel, a stent graft placement device is introduced into the blood vessel to deliver it to the lesion site, and the stent graft is released from the sheath to be brought into close contact with the blood vessel wall. It is an indwelling treatment method and has the advantage that the incision is small and the burden on the patient is small (minimally invasive).

Special Table 2019-516509

As disclosed in Patent Document 1, the stent graft has a tip (for example, the central side) of the stent graft in order to suppress the displacement of the living lumen from the indwelling site and to perform accurate indwelling. At the end), the end skeleton is arranged so as to protrude from the film. However, in such a stent graft, wrinkles are likely to occur in the film portion to which the end skeleton is connected, and there is a possibility that the adhesion to the living lumen may be lowered.

In addition, some stent grafts have a skeleton sewn to the coating. In order to properly fix the skeleton to the film, it is preferable that there are more sewing points. However, when the number of sewn portions increases, there is a problem that the flexibility is lowered, the followability to the living lumen is lowered, and the adhesion is lowered.

An object of the present invention is to provide a stent graft and a skeleton for a stent graft that can improve the adhesion to a living lumen.

The stent graft according to the present invention
A stent graft that is placed in the lumen of a living body.
A tubular body whose skeleton is covered with a film, and
An end skeleton arranged so as to protrude from the film is provided at one end of the main body in the axial direction.
The end skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction via a connecting portion.
The connecting portion has an inflection point that changes from a downward convex to an upward convex from the mountain portion to the valley portion.
The inflection point is connected to the film so that the protruding length of the end skeleton in the expanded state is shorter than the protruding length in the contracted state.

The stent graft according to the present invention
A stent graft that is placed in the lumen of a living body.
It has a tubular main body whose skeleton is covered with a film.
The main body skeleton has a first main body skeleton and a second main body skeleton arranged on one end side in the axial direction with respect to the first main body skeleton.
The second main body skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction, and is sewn to the film at a portion other than the valleys.

Further, the skeleton for stent graft according to the present invention is
A skeleton for stent grafts placed in the lumen of a living body.
The main body skeleton, which is placed in a tubular body covered with a film,
An end skeleton arranged so as to protrude from the film is provided at one end of the main body in the axial direction.
The end skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction via a connecting portion.
The connecting portion has an inflection point that changes from a downward convex to an upward convex from the mountain portion to the valley portion.

According to the present invention, the adhesion to the living lumen can be improved.

FIG. 1 is a diagram showing the appearance of a stent graft. FIG. 2 is a diagram schematically showing an indwelling state of the stent graft. FIG. 3 is an enlarged view of the bare portion. 4A and 4B are diagrams schematically showing the shape and length of the end skeleton in the expanded state and the contracted state, respectively. 5A and 5B are diagrams schematically showing a fixed mode of the second main body skeleton.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, as an example of the present invention, it is used when the lesion site (for example, aortic aneurysm B) of the descending aorta A (see FIG. 2) is expanded radially outward to treat an occlusion (stenosis). The stent graft 1 to be formed will be described.

FIG. 1 is a diagram showing the appearance of the stent graft 1. FIG. 2 is a diagram showing an indwelling state of the stent graft 1.

As shown in FIG. 1, the stent graft 1 has a main body portion 11 and a bare portion 12 arranged at the central end of the main body portion 11. Further, the main body portion 11 has a tubular shape that defines a blood flow path, and has a straight body portion 11a and a seal portion 11b connected to a central end portion of the body portion 11a. doing. The stent graft 1 is placed in the descending aorta A so that the bare portion 12 is on the upstream side (heart side) in the blood flow direction (see FIG. 2).

The stent graft 1 is composed of a skeleton 20 and a coating 30.
The skeleton 20 is a reinforcing member for maintaining the expanded state of the stent graft 1. The skeleton 20 is formed so as to be self-expandable from a contracted state contracted inward to an expanded state expanded outward in a radial direction substantially orthogonal to the axial direction.

The skeleton 20 includes a first main body skeleton 21 arranged on the body portion 11a, a second main body skeleton 22 arranged on the seal portion 11b, and an end skeleton 23 arranged on the bare portion 12. The first main body skeleton 21 and the second main body skeleton 22 are arranged on the peripheral surface of the film 30. For example, the peripheral skeleton 23 is fixed to the coating 30 on the peripheral side, and a part on the central side is exposed from the coating 30.
A fixing pin may be provided in the vicinity of the mountain portion 23a (bent portion on the central side) of the end skeleton 23 so as to project outward in the radial direction. As a result, the fixing pin bites into the blood vessel wall, and the displacement of the stent graft 1 can be prevented.

In the first main body skeleton 21 and the second main body skeleton 22, for example, one metal wire rod is alternately provided with mountain portions 21a and 22a (bent portions on the central side) and valley portions 21b and 22b (bent portions on the peripheral side). It is composed of a spiral skeleton that is spirally wound while bending in a zigzag shape (Z shape) so as to be formed. The first main body skeleton 21 and the second main body skeleton 22 are each wound in a spiral shape a plurality of times, and are arranged at predetermined intervals along their respective axial directions (extending direction of the stent graft 1). Further, in the present embodiment, the bending angles of the bending portions (mountain portions 21a, 22a and valley portions 21b, 22b) in the first main body skeleton 21 and the second main body skeleton 22 are set to be the same, and the bending portions of the sides sandwiching the bending portions are set to be the same. The lengths are set differently from each other.
The bending angle of the bent portion and the length of the side sandwiching the bent portion are not limited to this as an example, and can be arbitrarily changed as appropriate, and the bending angle may be different. The lengths of the sides may be the same. Further, the ends of the metal wires constituting the first main body skeleton 21 and the second main body skeleton 22 may be sewn and fixed to the film 30, for example, or the other parts or ends of the metal wires may be sewn to each other. It may be crimped and fixed.

In the end skeleton 23, for example, one metal wire rod is repeatedly formed in the circumferential direction with a mountain portion 23a (bent portion on the central side) and a valley portion 23b (bent portion on the peripheral side) via a connecting portion 23c. It is composed of an annulus skeleton bent in this way. The end skeleton 23 may be formed of a laser-cut type annulus skeleton formed by laser processing a metal cylindrical member. Further, the end portion of the metal wire rod constituting the end skeleton 23 may be sewn to the film 30 and fixed, or may be crimped and fixed to other parts or ends of the metal wire rod. good.

The cross-sectional areas of the wires forming the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 may be the same or different. When the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 are formed of a round wire rod, "cross-sectional area" may be read as "wire diameter".
Further, the cross-sectional area of the first main body skeleton 21 arranged on the body portion 11a may be set smaller than the cross-sectional area of the second main body skeleton 22 arranged on the seal portion 11b. As a result, the outer diameter of the main body 11 in the contracted state can be made smaller, and the storage property of the stent graft 1 in the sheath and the release property from the sheath are further improved.
If the adhesion to the blood vessel wall is ensured by at least the expanding force of the seal portion 11b, the inflow (end leak) of blood from the upstream side (central side) in the blood flow direction can be prevented, so that the seal portion 11b The expanding force of the body portion 11a located on the downstream side (peripheral side) in the blood flow direction may be smaller than the expanding force of the sealing portion 11b.

Further, in the end skeleton 23, the connecting portion 23c connecting the mountain portion 23a and the valley portion 23b is not linear as shown in FIG. 3 and the like, and the protruding length of the end skeleton 23 in the expanded state (FIG. 4A). (See) has a characteristic shape that is shorter than the protruding length in the contracted state (see FIG. 4B). 4A and 4B are development views showing the shape and length of the end skeleton 23, FIG. 4A shows an expanded state, and FIG. 4B shows a contracted state.

Specifically, the 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 the mountain portion 23a to the valley portion 23b. Here, "changing from a downward convex to an upward convex from the mountain portion 23a to the valley portion 23b" means that the inclination of the contact point gradually decreases and passes through an inclination of 0, as shown in FIG. 4A. In addition to the case where it gradually increases, it also includes the case where the inclination increases by bending at the inflection point as a boundary. Further, the entire connecting portion 23c may be an inflection point, or a part of the connecting portion 23c may be an inflection point.

Further, the connecting portion 23c is bent in a substantially "S" shape as a whole together with the mountain portion 23a and the valley portion 23b, for example, and the length of the connecting portion 23c is such that the mountain portion 23a and the valley portion 23b are linear. It is longer than the length when connected. In the end skeleton 23, the inflection point of the connecting portion 23c is sewn to the film 30 so that the protruding length in the expanded state is shorter than the protruding length in the contracted state. The explanation will be described later.

Further, in the first main body skeleton 21, the second main body skeleton 22 and the end skeleton 23, the peaks 21a, 22a, 23a and the valleys 21b, 22b, 23b are aligned on the axis of the stent graft 1. Is located in. As a result, the contractility when contracting the stent graft 1 is improved, and the storage property in the sheath and the release property from the sheath are improved.

Examples of the material forming the skeleton 20 include known metals or metal alloys typified by stainless steel, nickel-titanium alloy (nitinol), titanium alloy and the like. Further, an alloy material having X-ray contrast property may be used. In this case, the position of the stent graft 1 can be confirmed from outside the body. The skeleton 20 may be formed of a material other than the metal material (for example, ceramic or resin).

The material of the wire forming the skeleton 20, the wire type (for example, a circular wire such as a wire or a square wire obtained by laser cutting), the cross-sectional area (corresponding to the wire diameter in the case of a round wire), the number of bends in the circumferential direction, and The bending shape (the number of peaks and the shape of the peaks), the wire spacing in the axial direction (the amount of skeleton per unit length), and the like can be determined, for example, to the sheath required for each stent graft 1 according to the placement site. It is selected based on storability, release from the sheath, indwellability (corresponding to expanding force), and the like.

The membrane 30 is a membrane that forms a blood flow path. Examples of the material for forming the film 30 include a silicone resin, a fluororesin such as PTFE (polytetrafluoroethylene), and a polyester resin such as polyethylene terephthalate. The film thickness of the film 30 is preferably 80 μm or less, for example.

In the present embodiment, the first main body skeleton 21 is arranged on the outer peripheral surface of the film 30. As a result, when the stent graft 1 is placed, the first main body skeleton 21 arranged on the body portion 11a, which is the main part of the stent graft 1, is buried in the blood vessel wall, and the displacement of the stent graft 1 is effectively prevented. NS.

Further, the second main body skeleton 22 is arranged on the inner peripheral surface of the film 30. As a result, the adhesion of the seal portion 11b located on the central side to the blood vessel wall is enhanced, and end leakage from the central side is suppressed.

Further, the end skeleton 23 is arranged on the inner peripheral surface of the film 30 on the central side in a state where the central side is exposed. The portion of the end skeleton 23 protruding from the coating 30 is used for engagement with the hook of the delivery system, for example, when the stent graft 1 is placed using the delivery system (not shown) of the tip opening mechanism.

The arrangement mode of the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 in the film 30 is an example and is not limited to this, and can be arbitrarily changed as appropriate. For example, the film 30 sandwiches the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 so as to sandwich the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 on the outer peripheral surface side and the inner circumference. It may be arranged on the surface side. Further, the film 30 may be arranged on the outer peripheral surface side of the first main body skeleton 21, may be arranged on the inner peripheral surface side of the second main body skeleton 22, or may be arranged on the inner peripheral surface side of the end skeleton 23. May be placed in.

In the present embodiment, the skeleton 20 is sewn on the outer peripheral surface of the film 30 by the suture thread 40 (for example, polyethylene thread or polyester thread).

Specifically, in the first main body skeleton 21, the mountain portion 21a and the valley portion 21b are sewn on the film 30. In the second main body skeleton 22, only the mountain portion 22a is sewn to the film 30. As a result, the vicinity of the valley portion 22b of the second main body skeleton 22 can freely move with respect to the coating film 30, so that the flexibility of the sealing portion 11b is improved and the followability to the living lumen is improved. be able to.

Further, as shown in FIGS. 5A and 5B, the end portion 22d of the second main body skeleton 22 has a portion other than the bent portion sewn to the film 30. In the second main body skeleton 22, only the mountain portion 22a is fixed to the film 30, and the degree of freedom for the film 30 in the portion other than the mountain portion 22a is increased. Here, if the end portion 22d of the second main body skeleton 22 is firmly fixed to the coating portion 30, there is no escape for the force applied to the end portion 22d, and the degree of freedom of the entire second main body skeleton 22 with respect to the coating portion 30 is reduced. There is a risk of doing so. Therefore, in the present embodiment, the bent portion of the end portion 22d of the second main body skeleton 22 is not fixed, but is sewn and fixed at a portion other than the bent portion.

Specifically, the tip of the second main body skeleton 22 extends toward the position where the valley 22b will exist, and the end 22b is bent toward the mountain 22a so as to have an R shape. Consists of. The vicinity of the R portion of the end portion 22b (peripheral portion of the bent portion) is sewn. As a result, it is possible to prevent the end portion 22d of the second main body skeleton 22 from sticking into the blood vessel wall, and it is possible to prevent the end portion 22d from coming off from the sutured portion.
Further, as shown in FIG. 5B, the periphery of the end portion 22d of the second main body skeleton 22 may be covered with the patch 50. The patch 50 is formed of, for example, the same material as the film 30, and is fixed to the film 30 by suturing. As a result, it is possible to reliably prevent the end portion 22d from coming off from the sutured portion.

Although FIGS. 5A and 5B show the end portion on the central side of the second main body skeleton 22, the same end treatment is applied to the end portion on the erasing side. Further, the same end treatment as that of the second main body skeleton 22 may be applied to the end portion of the first main body skeleton 21. Further, the patch 50 may be fixed by adhesion other than fixing by suturing. Alternatively, the patch 50 may be formed of a heat-welded film and fixed to the film 30 by heat welding.

The sewing mode of the first main body skeleton 21, the second main body skeleton 22, and the end skeleton 23 to the film 30 is an example and is not limited to this, and can be arbitrarily changed as appropriate. For example, in the first main body skeleton 21, in addition to the mountain portion 21a and the valley portion 21b, the connecting portion 21c connecting the mountain portion 21a and the valley portion 21b may be sewn to the film 30. Further, in the second main body skeleton 22, in addition to the mountain portion 22a, at least one of the valley portion 22b and the connecting portion 22c may be sewn to the film 30.

In the end skeleton 23, the inflection point of the connecting portion 23c is sewn to the film 30 so that the protruding length in the expanded state is shorter than the protruding length in the contracted state. Specifically, substantially the center of the inflection portion of the connecting portion 23c is sewn to the film 30, and the mountain portion 23a side of the inflection portion is freely movable with respect to the film 30. As a result, the portion located at the open end of the film 30 in the expanded state (see FIG. 4A) protrudes from the film 30 in the contracted state (see FIG. 4B). In other words, the portion protruding from the film 30 in the contracted state is also located at the open end of the film 30 in the expanded state, and contributes to the expansion of the film 30.
Therefore, at the time of expansion, the length (skeleton amount) of the end skeleton 23 located at the open end of the film 30 becomes long in the bare portion 12, and the end skeleton 23 is not arranged at the open end of the film 30. Since the portion is relatively small and the coating film 30 is appropriately expanded, the coating film 30 is less likely to be wrinkled, and the adhesion to the descending portion A of the aorta can be improved. In addition, the central end of the stent graft 1 can be reliably expanded and opened.
In particular, the end skeleton 23 is shaped so as to extend the inflection point of the connecting portion 23c along the open end portion of the film 30 in the expanded state, that is, the extending direction of the open end portion of the film 30. The film 30 can be expanded more appropriately by lengthening a portion having a small inclination with respect to a relative portion, preferably a portion having a substantially zero inclination.

Further, when the stent graft 1 is contracted, the tip portion (mountain portion 23a) of the end skeleton 23 protrudes from the coating film 30 for a long time, so that a delivery system of a tip opening mechanism for placing the stent graft 1 (not shown). Can be more properly engaged with the hook.

As described above, the stent graft 1 according to the embodiment is a stent graft indwelled in the descending part A (living lumen) of the aorta, and the first main body skeleton 21 and the second main body skeleton 22 (main body skeleton) are covered with a film 30. It includes a tubular main body 11 covered with, and an end skeleton 23 arranged so as to protrude from the coating 30 at a central end (one end in the axial direction) of the main body 11. The end skeleton 23 is formed by bending a wire rod so that a mountain portion 23a and a valley portion 23b repeat in the circumferential direction via a connecting portion 23c. Further, the connecting portion 23c has an inflection point that changes from a downward convex to an upward convex from the mountain portion 23a to the valley portion 23b, and the protruding length of the end skeleton 23 in the expanded state is in the contracted state. The inflection point is connected to the film 30 so as to be shorter than the protruding length of the above.
As a result, the length (skeleton amount) of the end skeleton 23 located near the opening of the film 30 can be secured as long as possible in the expanded state. Therefore, the portion of the open end of the film 30 where the end skeleton 23 is not arranged is relatively small, and the film 30 is appropriately expanded, so that the film 30 is less likely to wrinkle and is in contact with the descending aorta. Adhesion can be improved.

Further, in the end skeleton 23, substantially the center of the inflection point is connected to the film 30. As a result, the mountain portion 23a side of the connecting portion 23c can freely move with respect to the film 30, and is located at the open end of the film 30 in the expanded state, while protruding from the film 30 in the contracted state. Therefore, the film 30 can be appropriately expanded at the time of expansion, and the contractility in the radial direction is improved so that the film 30 can be easily stored in the sheath.

Further, the first main body skeleton 21 and the second main body skeleton 22 (main body skeleton) are formed so that the mountain portions 21a and 22a and the valley portions 21b and 22b repeat in the circumferential direction by bending the wire rod, and the first main body skeleton 21 , The mountain portions 21a, 22a, 23a of the second main body skeleton 22 and the end skeleton 23, and the valley portions 21b, 22b, 23b are arranged so as to be aligned in the axial direction. As a result, the contractility when contracting the stent graft 1 is improved, and the storage property in the sheath and the release property from the sheath are improved.

Further, the second main body skeleton 22 is sewn to the film 30 at the mountain portion 22a (the portion other than the valley portion 22b). As a result, the vicinity of the valley portion 22b of the second main body skeleton 22 can freely move with respect to the coating film 30, so that the flexibility of the sealing portion 11b is improved and the followability to the living lumen is improved. be able to.

Further, the second main body skeleton 22 is sewn on the inner peripheral side of the film 30. As a result, the adhesion of the seal portion 11b located on the central side to the living lumen wall is enhanced, and end leakage from the central side is suppressed.

Further, the end portion 22d of the second main body skeleton 22 is sewn to the film 30 at a portion other than the bent portion without being sewn to the film 30 at the bent portion. As a result, the degree of freedom of the entire second main body skeleton 22 with respect to the coating 30 can be increased by not fixing the bent portion of the end portion 22d, and as a result, the flexibility of the stent graft 1 is improved and the luminal wall of the living body is covered. Adhesion can be improved.

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment and can be changed without departing from the gist thereof.

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 11 and the end skeleton 23 of the bare part 12 have a predetermined expansion force. However, not all skeletons 21-23 need to have a predetermined expanding force.

Further, the first main body skeleton 21 and the second main body skeleton 22 are spiral skeletons in which one metal wire is spirally wound while being bent in a zigzag shape. For example, a plurality of annular skeletons are axially oriented. It may be arranged so as to be separated from each other. Further, the end skeleton 23 is an annular skeleton in which one metal wire rod is bent in a zigzag shape and extended in the circumferential direction, but for example, it may be wound in a spiral shape.

The present invention is not limited to the stent graft 1 placed in the descending aorta A (see FIG. 2), but can be applied to a stent graft placed in a living lumen such as a digestive system lumen or another blood vessel. Further, the stent graft 1 may have a bifurcated or more branched end on the downstream side in the blood flow direction.

Further, in the embodiment, the main body portion 11 has a curved shape along the lumen shape after indwelling, but the present invention is not limited to this, and may have a straight cylinder shape. , It may have a curved shape depending on the indwelling site.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The disclosures of the specifications, drawings and abstracts contained in the Japanese applications of Japanese Patent Application No. 2020-035005 filed on March 2, 2020 and Japanese Patent Application No. 2020-042584 filed on March 12, 2020 are all incorporated herein by reference. NS.

1 Stent graft 11 Main body 11a Body 11b Seal 12 Bare 20 Skeleton 21 1st main body skeleton 22 2nd main body skeleton 23 End skeleton 21a, 22a, 23a Mountain part 21b, 22b, 23b Tani part 21c, 22c, 23c connection Part 22d End 30 Film

Claims (9)

A stent graft that is placed in the lumen of a living body.
A tubular body whose skeleton is covered with a film, and
An end skeleton arranged so as to protrude from the film is provided at one end of the main body in the axial direction.
The end skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction via a connecting portion.
The connecting portion has an inflection point that changes from a downward convex to an upward convex from the mountain portion to the valley portion.
A stent graft in which the inflection point is connected to the coating so that the protruding length of the end skeleton in the expanded state is shorter than the protruding length in the contracted state. The stent graft according to claim 1, wherein the inflection point extends along the open end of the coating in the expanded state. The stent graft according to claim 2, wherein substantially the center of the inflection point is connected to the coating film. The main body skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction.
The stent graft according to any one of claims 1 to 3, wherein the main body skeleton and the end skeleton are arranged so that the peaks and valleys of each other are aligned in the axial direction. The main body skeleton has a first main body skeleton and a second main body skeleton arranged on one end side in the axial direction with respect to the first main body skeleton.
2. The stent graft according to any one item. A stent graft that is placed in the lumen of a living body.
It has a tubular main body whose skeleton is covered with a film.
The main body skeleton has a first main body skeleton and a second main body skeleton arranged on one end side in the axial direction with respect to the first main body skeleton.
The second main body skeleton is a stent graft in which a wire rod is bent so that peaks and valleys repeat in the circumferential direction, and is sewn to the film at a portion other than the valleys. The stent graft according to claim 6, wherein the second main body skeleton is sewn on the inner peripheral side of the film. The main body skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction.
The stent graft according to claim 6 or 7, wherein the end portion of the main body skeleton is sewn to the coating film at a portion other than the bending portion without being sewn to the coating film. A skeleton for stent grafts placed in the lumen of a living body.
The main body skeleton, which is placed in a tubular body covered with a film,
An end skeleton arranged so as to protrude from the film is provided at one end of the main body in the axial direction.
The end skeleton is formed by bending a wire rod so that peaks and valleys repeat in the circumferential direction via a connecting portion.
The connecting portion is a skeleton for stent grafting, which has an inflection point that changes from a downward convex to an upward convex from the mountain portion to the valley portion.

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