Stent graft

Abstract

The present invention provides a covered stent, comprising a main body, the main body comprising a proximal segment, a distal segment and an intermediate segment located between the proximal segment and the distal segment, the intermediate segment comprising an intermediate unit and at least one bare stent segment, a gap being formed between the outer surfaces of the bare stent segment and the intermediate unit; the main body having an inner cavity running through the proximal segment, the distal segment and the intermediate unit, the gap being connected to the inner cavity; the projection of the intermediate unit on a certain cross section of the main body having a first boundary, the projection of the proximal segment on the cross section having a second boundary, the projection of the distal segment on the cross section having a third boundary, the first boundary being within the second boundary and within the third boundary. The present invention solves the technical problem of the prior art covered stents that, before the branch vessels are reconstructed, the branch vessels are always in an ischemic state, and the probability of postoperative complications is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of interventional medical devices, and in particular relates to a stent graft. Background Art

[0002] Aortic aneurysm and aortic dissection are diseases that currently pose a serious threat to human life. If not actively treated, aortic aneurysm and aortic dissection will continue to grow and eventually rupture, causing serious complications or even death. With the increasing number of patients with hypertension, hyperlipidemia and hyperglycemia, the incidence of aortic aneurysm and aortic dissection is also increasing significantly.

[0003] Traditional open surgical treatments for aortic aneurysms and aortic dissections are highly invasive, have high mortality rates, long operative times, high rates of postoperative complications, and high surgical difficulty. Endovascular treatment, on the other hand, is characterized by minimal trauma, fewer postoperative complications, shorter operative times, and lower surgical difficulty, and has gradually become the primary method for treating aortic aneurysms and aortic dissections. Endovascular treatment primarily involves implanting a covered stent in the aorta to isolate the diseased portion of the vessel outside the covered stent and restrict blood flow through the inside of the covered stent, thereby protecting the blood vessels. To ensure post-implant fixation of the covered stent and to prevent blood flow from flowing into the blood vessels through the proximal and distal ends of the covered stent, the covered stent requires a certain length of anchoring area for fixation. Therefore, when an aortic aneurysm or aortic dissection involves a branch artery, the implanted covered stent will block the branch artery to varying degrees, and may even make endovascular treatment impossible, leading to surgical failure.

[0004] For endovascular treatment of aortic aneurysms or aortic dissections involving branch arteries, fenestrated stent technology and chimney stent technology are often used to ensure blood flow to the branch arteries. Fenestrated stent technology involves creating a fenestration in the stent graft, either in vitro or in situ, to create a side hole in the stent. The side hole is positioned to align with the opening of the branch artery. During the procedure, a bridging stent is implanted with the opening aligned with the branch artery. The bridging stent is then implanted through the branch artery to coordinate with the stent graft. Chimney stent technology involves implanting the stent graft and then inserting a bridging stent through the branch artery to coordinate with the stent graft.

[0005] Fenestrated stent technology is difficult to position and requires customization, which takes a long time and cannot meet emergency needs, and the stent structure is easily damaged; chimney stent technology is prone to internal leakage and is limited by vascular anatomy, making it difficult to reconstruct multiple branch arteries; at the same time, whether using fenestrated stent technology or chimney stent technology, the branch arteries are always in a state of ischemia before they are reconstructed, and the probability of postoperative complications is high. Summary of the Invention

[0006] The purpose of the present invention is to provide a covered stent, aiming to solve the technical problem of the existing covered stent in that the branch vessels are always in an ischemic state before they are reconstructed, and the probability of postoperative complications is high.

[0007] The present invention provides a stent graft, comprising:

[0008] a main body, the main body comprising a proximal segment, a distal segment, and an intermediate segment located between the proximal segment and the distal segment, the intermediate segment comprising an intermediate unit and at least one bare stent segment, a gap being formed between at least a portion of the bare stent segment and an outer surface of the intermediate unit;

[0009] The main body has an inner cavity running through the proximal section, the distal section and the middle unit, and the gap is in communication with the inner cavity;

[0010] The projection of the intermediate unit on a certain cross section of the main body has a first boundary, the projection of the proximal segment on the cross section has a second boundary, the projection of the distal segment on the cross section has a third boundary, and the first boundary is located within the second boundary and within the third boundary.

[0011] In one embodiment, the intermediate unit includes a tubular intermediate segment membrane, and the inner cavity formed by the intermediate segment membrane is connected to the inner cavity of the proximal segment and the inner cavity of the distal segment.

[0012] In one embodiment, the intermediate covering includes a first intermediate covering and a second intermediate covering connected to the first intermediate covering, and the first intermediate covering and the second intermediate covering together form an inner cavity of the intermediate unit.

[0013] In one embodiment, the middle segment coating covers a portion of the bare stent segment in the circumferential direction, and the uncovered portion of the bare stent segment forms an exposed portion, and the gap is formed between the exposed portion and the outer surface of the middle segment coating.

[0014] In one embodiment, the intermediate segment coating includes a tubular third intermediate coating, which is disposed in the inner cavity formed by the bare stent segment and is separated from the bare stent segment.

[0015] In one embodiment, the bare stent segment includes a plurality of annular waves arranged along the axial direction of the main body, and among the plurality of annular waves, at least two adjacent waves are movable relative to each other.

[0016] In one embodiment, at least one window is provided on the intermediate unit, and the window communicates with the gap and the inner cavity of the intermediate unit.

[0017] In one embodiment, the stent graft further includes an embedded branch having an inner cavity. The embedded branch is disposed in the inner cavity of the main body, and the inner cavity of the embedded branch is communicated with the gap.

[0018] In one embodiment, the embedded branch includes a proximal tube body correspondingly arranged in the proximal segment and a distal tube body correspondingly arranged in the distal segment, and the inner cavities of the proximal tube body and the distal tube body are both connected to the inner cavity of the main body.

[0019] In one embodiment, the embedded branch also includes a proximal transition section connecting the gap and the proximal tube body, and a distal transition section connecting the gap and the distal tube body, the proximal transition section and the distal transition section are both trumpet-shaped, and the narrowing end of the trumpet-shaped proximal transition section is toward the proximal end of the main body, and the narrowing end of the trumpet-shaped distal transition section is toward the distal end of the main body.

[0020] In one embodiment, one end of the intermediate segment covering is connected to the proximal segment via a proximal sealing membrane, and the other end is connected to the distal segment via a distal sealing membrane.

[0021] In one embodiment, the diameter of the bare stent segment is greater than or equal to the diameter of the proximal segment and / or the distal segment.

[0022] In one embodiment, the central axis of the bare stent segment is closer to the embedded branch than the central axis of the intermediate unit.

[0023] The beneficial effects of the present invention are as follows: by providing proximal and distal segments with larger radial dimensions, a good supporting effect can be provided for the lumen, so that a gap is formed between the narrowed middle unit and the inner wall of the lumen. After implantation into the target lumen, the middle segment of the main body is squeezed less than the proximal and distal segments, so the blood flow in the middle segment is more stable, and a larger operating space is provided for the bridging stent connected to the outside of the middle segment. For twisted lumens, especially those with smaller true lumens, a more stable operating space is provided during surgery by providing a bare stent segment, which can avoid compression of the operating space due to squeezing of the middle unit by the lumen. In addition, the bare stent segment can also enhance the anchoring force of the middle part of the coated stent, greatly reducing the risk of displacement after implantation into the blood vessel. At the same time, since the middle part of the coated stent has reliable support, the swinging of the bridging stent with the blood flow can be avoided or reduced, thereby ensuring the stability of blood supply and facilitating the implantation of the bridging stent, and avoiding prolonged ischemia of the branch vessels. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a three-dimensional schematic diagram of the stent graft provided in Example 1 of the present invention;

[0025] Figure 2 This is a schematic diagram showing the tangent boundary of the projections of the proximal segment and the middle segment of the stent graft provided in the first embodiment of the present invention in a direction perpendicular to the axis of the main body;

[0026] Figure 3 Schematic diagram of an embodiment of the stent graft provided in the first embodiment of the present invention, wherein the embedded branch is provided with two proximal tube bodies;

[0027] Figure 4 yes Figure 3 Schematic diagram of the end face of the covered stent;

[0028] Figure 5 is a schematic diagram of an embedded branch provided in Example 1 of the present invention;

[0029] Figure 6 is another three-dimensional schematic diagram of the stent graft provided in Example 1 of the present invention;

[0030] Figure 7 1 is an exploded schematic diagram of the main body coating provided in Example 1 of the present invention;

[0031] Figure 8 Schematic diagram of the base film and proximal transition section of the branch coating provided in Example 1 of the present invention;

[0032] Figure 9 is a schematic front view of a proximal transition section provided in the first embodiment of the present invention;

[0033] Figure 10 is a three-dimensional schematic diagram of a stent graft provided in Example 2 of the present invention;

[0034] Figure 11 is another three-dimensional schematic diagram of the stent graft provided by the second embodiment of the present invention;

[0035] Figure 12 This is a partial exploded schematic diagram of the stent graft and branch grafts provided in the second embodiment of the present invention;

[0036] Figure 13 is a schematic structural diagram of a stent graft provided by another embodiment of the present invention;

[0037] Figure 14 is an exploded schematic diagram of a membrane in a stent graft provided by another embodiment of the present invention;

[0038] 100. Covered stent;

[0039] 1. Subject;

[0040] 10. Main stent; 11. Proximal segment; 12. Middle segment; 13. Distal segment; 14. Main body covering; 101. Annular wave ring;

[0041] 111, proximal main body support; 122, exposed portion; 131, distal main body support; 141, proximal main body covering; 142, distal main body covering; 143, first intermediate covering;

[0042] 121a / 121b, bare stent segment;

[0043] 2. Embedded branches;

[0044] 20. Embedded stent; 21. Branch covering; 22. Proximal tube body; 23. Intermediate unit; 24. Distal tube body; 25. Proximal transition section; 26. Distal transition section; 27. Proximal external opening; 28. Distal external opening; 251. Arc-shaped sheet; 252. Transition section bottom sheet; 211. Second intermediate covering; 231. Third intermediate covering; 232. Window;

[0045] 30. Proximal sealing membrane; 301. First through-hole;

[0046] 40. Distal sealing membrane; 401. Second through-hole. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] It should be noted that when an element is referred to as being “fixed to” or “disposed on” another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0049] In the field of medical devices, the end where blood flows in is defined as the "proximal end" and the direction where blood flows out is defined as the "distal end". For example, after a stent is implanted in the body, blood flows from the proximal end of the stent to the distal end of the stent.

[0050] It should also be noted that the directional terms such as left, right, up, and down in this embodiment are merely relative concepts or are based on the normal use status of the product, and should not be considered as restrictive.

[0051] Example 1

[0052] See also Figure 1The stent graft 100 provided in the first embodiment of the present invention includes a main body 1 and embedded branches 2, each of which has an inner lumen. The main body 1 includes a tubular main stent 10 and a main body graft 14 covering the main stent 10. More specifically, the main body 1 has a proximal segment 11 at the proximal end, an intermediate segment 12, and a distal segment 13 at the distal end, with the intermediate segment 12 located between the proximal segment 11 and the distal segment 13.

[0053] Please also refer to Figure 6 The intermediate section 12 includes an intermediate unit 23 and at least one bare stent segment 121a. The bare stent segment 121a is disposed outside the intermediate unit 23 and forms a gap (or void, cavity) with the outer surface of the intermediate unit 23. The main body 1 has an inner cavity that passes through the proximal section 11, the distal section 13, and the intermediate unit 12, and the inner cavity is connected to the above-mentioned gap.

[0054] The projection of the intermediate unit 23 on a certain cross section A of the main body 1 (i.e., a plane perpendicular to the axial direction of the main body 1) (the "projection" mentioned in the present invention refers to the positive projection) has a first boundary, the projection of the proximal segment 11 on the cross section A has a second boundary, and the projection of the distal segment 13 on the cross section A has a third boundary. The first boundary is located within the second boundary and within the third boundary.

[0055] The coated stent 100 of this embodiment can provide good support for the lumen by providing a proximal segment 11 and a distal segment 13 with larger radial dimensions, so that a gap is formed between the narrowed middle unit 23 and the inner wall of the lumen. After implantation into the target lumen, the middle segment 12 of the main body 1 is less squeezed than the proximal segment 11 and the distal segment 13, so the blood flow in the middle segment 12 is smoother and more stable, and a larger operating space is provided for the middle segment 12 to be connected to the external bridging stent. For twisted lumens, especially those with smaller true lumens, the bare stent segment 121a is provided as a portion to avoid compression of the operating space due to squeezing of the lumen on the middle unit 23 during surgery, thereby providing a more stable operating space. In addition, the bare stent segment 121a can also enhance the anchoring force of the middle portion of the coated stent 100, thereby greatly reducing the risk of displacement after implantation in the blood vessel. At the same time, the bridging stent can pass through the bare stent segment 121a to communicate with the embedded branch 2, so the coated stent 100 has a reliably supported middle portion to avoid or reduce the occurrence of the bridging stent swinging with the blood flow, thereby ensuring the stability of blood supply and avoiding prolonged ischemia of the branch vessels.

[0056] See also Figure 2 In this embodiment, the projections of the proximal segment 11 and the middle segment 12 on the cross section A of the main body 1 are tangent to each other and form a tangent point P. There is a partially uncovered area on the bare stent segment 121a (refer to Figure 6 The exposed portion 122 in the cross section A is located at the projection of the exposed portion 122.

[0057] This embodiment makes the projected boundaries of the proximal segment 11 and the middle segment 12 on the cross section of the main body 1 tangent, so that the coated stent 100 has a better wall adhesion effect and prevents the formation of steps on the proximal segment 11 and the middle segment 12 that are prone to wear of blood vessels. In addition, it can also prevent the size of the coated stent 100 from being too large after radial compression, which is conducive to sheathing and release.

[0058] Bare stent segment Bare stent segment Please see again Figure 2 The tangent point P is located on the projection of the exposed portion 122 on the cross-section A, for example, approximately at the 12 o'clock position of the proximal end opening of the middle section 12 on the cross-section A. In other embodiments, the tangent point P may also be located on the projection of the cross-section A at an angle a relative to the 12 o'clock direction of the proximal end opening of the middle section 12, and a is less than 60°. That is, the tangent point P may be offset to the left or to the right of the 12 o'clock direction of the proximal end opening of the middle section 12, and the central angle a′ of the distribution range of the projection of the edge of the proximal end opening of the middle section 12 on the cross-section A is less than 120°. In other words, the exposed portion 122 is generally arc-shaped, and the central angle corresponding to the projection of the exposed portion 122 on the cross-section A is less than or equal to 120 degrees. Since the three major branches of the aortic arch are drawn upward from the convex side of the arch, when the tangent point P is set at the above position, when the covered stent is used in the arch blood vessel and the bare stent segment 121a is close to the large bend side (i.e. the side with a large bending radius), the proximal segment 11 and the middle segment 12 can fit more closely with the inner wall of the blood vessel, ensuring the stability of the position of the proximal segment 11 and the middle segment 12 of the stent, and the subsequent bridging stent can be smoothly implanted into the bare stent segment 121a. Please refer again Figure 1 、 Figure 6 In this embodiment, the main stent 10 includes a plurality of axially arranged annular corrugations 101, and the main body coating 14 covers the outside and / or inside of each annular corrugation 101. That is, the main body coating 14 can be attached to the outside and inside of the annular corrugations 101 in sections, or can be attached to the outside or inside of the annular corrugations 101 simultaneously. The embedded branch 2 of the coated stent 100 provided in this embodiment of the present invention is disposed within the inner cavity of the main body 1 and maintains communication with the inner cavity of the main body 1, so that blood flow in the inner cavity of the main body 1 can maintain a flow with blood flow in the embedded branch 2.

[0059] The bare stent segment 121a includes a plurality of annular wave rings 101 located in the middle segment 12 of the main stent 10, and each annular wave ring 101 includes a plurality of wave crests and wave troughs.

[0060] The intermediate unit 23 includes a tubular intermediate section coating. The inner cavity formed by the intermediate section coating is connected to the inner cavity of the proximal section 11 and the inner cavity of the distal section 13. The intermediate section coating covers a portion of the bare stent segment 121a in the circumferential direction, and the uncoated portion of the bare stent segment 121a forms an exposed portion 122, and a gap is formed between the exposed portion 122 and the outer surface of the intermediate section coating. In other embodiments, the exposed portion 122 includes at least a pair of adjacent crests and troughs in the axial direction that are hooked and connected to each other and can move relative to each other, which is beneficial to improving the radial support force of the exposed portion 122 and can better reduce the probability of the implanted bridging stent swinging with the blood flow.

[0061] In this embodiment, the middle section of the coating includes a first middle coating 143 and a second middle coating 211 connected to the first middle coating 143. The first middle coating 143 and the second middle coating 211 enclose an inner cavity of the middle unit 23.

[0062] See also Figure 3 、 Figure 4 and Figure 5 The embedded branch 2 may include an embedded stent 20 and a branch covering 21 covering the embedded stent 20. The branch covering 21 may cover the inner side and / or the outer side of the embedded stent 20. The main covering 14 and the branch covering 21 may be integrally formed by a single covering, or may be formed by splicing multiple coverings by suturing, bonding, or the like. The embedded stent 20 and the branch covering 21, as well as the main stent 10 and the main covering 14, may be fixed by suturing, bonding, or the like.

[0063] As a specific embodiment, the embedded branch 2 includes a proximal tube body 22 corresponding to the proximal segment 11 of the main body 1 and a distal tube body 24 corresponding to the distal segment 13 of the main body 1. The inner lumens of the proximal tube body 22 and the distal tube body 24 are both connected to the inner lumen of the main body 1, and are connected to the gap formed by the outer surface of the intermediate unit 23 and the bare stent segment 121a. Among them, the proximal tube body 22 and the distal tube body 24 can be set to only 0 or more. For example, when it is applied to the aortic arch, two proximal tube bodies 22 can be set and one distal tube body 24 can be set; or one proximal tube body 22 can be set and two distal tube bodies 24 can be set, or all can be set at the proximal end or distal end. The specific setting and selection can be made according to the number and position of the bridging stents to be connected. Therefore, it can meet the needs of emergency surgery in clinical use and avoid the need for long waiting times for customization and missing the best time for treatment. The presence or absence and the number of the proximal tube body 22 and the distal tube body 24 can be set accordingly according to actual possible situations, so as to design various specifications of the coated stent 100 for optimal selection for clinical emergency needs. Therefore, its specific implementation method is not limited to the above-mentioned embodiments.

[0064] In this embodiment, the proximal tube body 22 is connected to the second intermediate coating 211 via a proximal transition section 25, and the distal tube body 24 is connected to the second intermediate coating 211 via a distal transition section 26. The proximal transition section 25 penetrates the proximal tube body 22, and the distal transition section 26 penetrates the distal tube body 24. The distal end of the proximal transition section 25 has a proximal external opening 27 that communicates with the gap, and the proximal end of the distal transition section 26 has a distal external opening 28 that communicates with the gap. The proximal external opening 27 of the proximal transition section 25 is disposed opposite the distal external opening 28 of the distal transition section 26. In some embodiments, both the proximal and distal transition sections 25 and 26 can be configured in a trumpet shape, with the tapered end of the trumpet-shaped proximal transition section 25 facing the proximal end of the main body 1, and the tapered end of the trumpet-shaped distal transition section 26 facing the distal end of the main body 1. During surgery, the bridging stent can be accessed through the proximal outer opening 27 and the distal outer opening 28. It is understood that the bare stent segment 121a should be compatible with the bridging stent so that the bridging stent can pass through the gap between adjacent coils on the bare stent segment 121a and access the proximal outer opening 27 or the distal outer opening 28 of the embedded branch 2. The expanded ends of the proximal transition segment 25 and the distal transition segment 26 are both oriented toward the middle segment 12, that is, toward the bare stent segment 121a, and gradually contract in a direction away from the bare stent segment 121a. This provides the bridging stent with a relatively large implantation guide path in the initial stage of implantation, facilitating rapid implantation of the bridging stent and gradually contracting its implantation path, thereby facilitating more precise and stable implantation of the bridging stent. After the bridging stent is implanted into the embedded branch 2, the bare stent segment 121a provides a certain degree of fixation to it, thereby preventing the bridging stent from swinging with the blood flow, making the bridging stent relatively more stable. In addition, the embedded branch 2 and the exposed portion 122 can be located on the same side of the coated stent 100 to reduce the path length of the bridging stent accessing the embedded branch 2 and facilitate the implantation of the bridge stent.

[0065] See also Figure 5 、 Figure 6 and Figure 7In some more specific embodiments, the proximal segment 11 includes a tubular proximal main body stent 111 and a proximal main body coating 141. The proximal main body coating 141 can be applied to the inner or outer side of the proximal main body stent 111 by suturing, bonding, or other methods. The distal segment 13 includes a tubular distal main body stent 131 and a distal main body coating 142. The distal main body coating 142 can also be applied to the distal main body stent 131 by suturing, bonding, or other methods. Both the proximal main body coating 141 and the distal main body coating 142 are part of the main body coating 14. The intermediate segment 12 can include a bare stent segment 121a, a first intermediate coating 143 that partially covers the bare stent segment 121a in the circumferential direction, and a second intermediate coating 211 connected to the first intermediate coating 143. The first intermediate coating 143 is also part of the main body coating 14. The portion of the bare stent segment 121a not attached with the first intermediate coating 143 is the exposed portion 122. As a specific embodiment of the bare stent segment 121a, the bare stent segment 121a includes a plurality of annular wave rings 101 arranged at intervals along the axial direction of the main body 1, and a first intermediate coating 143 is covered on the inner side and / or outer side of each annular wave ring 101. The first intermediate coating 143 is an arc-shaped sheet structure.

[0066] See also Figure 5 、 Figure 6 、 Figure 7 and Figure 8 The intermediate unit 23 includes a first intermediate covering 143 with an arcuate sheet structure and a second intermediate covering 211 connected to the first intermediate covering 143 to form a circumferentially sealed cavity. The cavity enclosed by the second intermediate covering 211 and the first intermediate covering 143 constitutes the inner cavity of the intermediate unit 23. In this embodiment, the second intermediate covering 211 is a sheet structure that is generally coplanar, or alternatively, the second intermediate covering 211 is an arcuate sheet structure, but its curvature is smaller than that of the first intermediate covering 143. This ensures a sufficient gap between the second intermediate covering 211 and the exposed portion 122, providing adequate operating space for implanting the bridging stent.

[0067] In some embodiments, the diameter of the proximal segment 11 is D1, the diameter of the middle segment 12 is D2, and the diameter of the distal segment 13 is D3, wherein D1>D2 and D3>D2. In some more specific embodiments, D2 ≥ 0.7×D1. That is, the diameter of the middle segment 12 is smaller than the diameters of the proximal segment 11 and the distal segment 13, and the stent graft 100 is configured as a structure with a reduced diameter in the middle. In addition to ensuring stable support for the middle segment 12 of the stent graft 100, the stent graft 100 within the above value range can also provide a more suitable operating space for the implantation of the bridging stent. Figure 5 、 Figure 8 、 Figure 9In a specific implementation, the proximal transition section 25 can be formed by connecting an arcuate sheet 251 and a transition section bottom sheet 252 through sewing, gluing, or other methods. The transition section bottom sheet 252 can be a separate sheet structure or integrally formed with the second intermediate film 211. Specifically, the proximal end of the second intermediate film 211 extends partially toward the proximal transition section 25 to form the transition section bottom sheet 252, thereby forming part of the proximal transition section 25. In other embodiments, the proximal transition section 25 can also be integrally formed from a trumpet-shaped membrane. It is understood that the structure and manufacturing method of the distal transition section 26 can be determined by reference to the structure and manufacturing method of the proximal transition section 25, or by reference to the configuration methods in the aforementioned embodiments, and will not be further described here.

[0068] Example 2

[0069] See also Figure 10 、 Figure 11 and Figure 12 , are various relevant schematic diagrams of the coated stent provided in the second embodiment of the present invention. The main difference between the second embodiment and the first embodiment lies in the middle section 12. In this embodiment, the middle section 12 includes an intermediate unit 23 and a bare stent section 121b. The bare stent section 121b of this embodiment is tubular as a whole, and no coating is provided on the bare stent section 121b. The two ends of the bare stent section 121b are respectively connected to the distal end of the proximal section 11 and the proximal end of the distal section 13. For example, the bare stent section 121b includes a plurality of annular waves 101 arranged side by side and spaced apart along the axial direction of the main body 1, and the adjacent annular waves 101 are hooked and connected and can move relative to each other. The annular wave 101 located at the nearest end is connected to the distal end of the proximal section 11 of the main body 1, and the annular wave 101 located at the farthest end is connected to the proximal end of the distal section 13 of the main body 1. In this way, the structural integrity of the coated stent 100 can be met, and the bridging stent can also be easily connected from the gap of the bare stent section 121b.

[0070] In this embodiment, the intermediate unit 23 includes a third intermediate coating 231 in a tubular shape. The two ends of the third intermediate coating 231 are fixedly connected to the proximal segment 11 and the distal segment 12, respectively. The third intermediate coating 231 is disposed in the inner cavity formed by the bare stent segment 121b and is separated from the bare stent segment 121b. In this embodiment, the intermediate unit 23 may also include an intermediate segment bracket disposed on the third intermediate coating 231 to support and fix the third intermediate coating 231. For example, the intermediate segment bracket may include a plurality of corrugations arranged at intervals in the axial direction. The radial force of the intermediate segment bracket disposed on the third intermediate coating 231 may be smaller than the radial force of the bare stent segment 121b to reduce the difficulty of loading the coated stent 100. In other embodiments of the present invention, the third intermediate coating 231 may not be supported by a supporting skeleton such as corrugations.

[0071] One end of the middle section covering film may be connected to the proximal section 11 via the proximal sealing film 30 , and the other end may be connected to the distal section 13 via the distal sealing film 40 .

[0072] In a specific embodiment, both the proximal sealing membrane 30 and the distal sealing membrane 40 are sheet-like structures. A portion of the edge of the proximal sealing membrane 30 is connected to the edge of the proximal external opening 27, while the remaining portion is connected to the distal edge of the proximal segment 11. A portion of the edge of the distal sealing membrane 40 is connected to the edge of the distal external opening 28, while the remaining portion is connected to the proximal edge of the distal segment 13. The proximal sealing membrane 30 defines a first through-hole 301, which connects the inner lumen of the third intermediate covering 231 with the inner lumen of the proximal segment 11. The distal sealing membrane 40 defines a second through-hole 401, which connects the inner lumen of the third intermediate covering 231 with the inner lumen of the distal segment 13. It is understood that the proximal sealing membrane 30 and the distal sealing membrane 40 may be inclined to provide a smooth transition between the proximal segment and the intermediate portion 23, thereby minimizing the impact on blood flow.

[0073] In some embodiments, the diameter of the bare stent segment 121b can be greater than or equal to the diameter of the proximal segment 11 and the distal segment 13 at the same time. At the same time, the diameter of the bare stent segment 121b can also be greater than or equal to the diameter of any one of the proximal segment 11 and the distal segment 13. When the diameter of the bare stent segment 121b is equal to the diameter of the proximal segment 11 and / or the distal segment 13, when the middle segment 12 is squeezed, due to the support of the bare stent segment 121b, the third intermediate coating 231 will basically not be squeezed, ensuring smooth blood flow in the main body; when the diameter of the bare stent segment 121b is greater than the diameter of the proximal segment 11 and / or the distal segment 13, after implantation into the target blood vessel, the bare stent segment 121b will first bear radial pressure, and the radial pressure it bears is greater than the radial pressure of the proximal segment 11 and the distal segment 13, which can provide a more stable and stronger radial support force for the main stent 10, thereby having better anti-displacement performance. In some more specific embodiments, the diameter of the bare stent segment 121b is set to D4, and the diameter of the proximal segment 11 is set to D5. The ratio of D4 to D5 can be set within a range of 1 to 1.2. In this case, the bare stent segment 121b not only provides greater radial support but also provides more maneuvering space for the implantation of the bridging stent. It is understood that in other embodiments, D4 can also be smaller than D5, as long as the bare stent segment 121b can provide good support for the intermediate segment 12 and provide sufficient maneuvering space for the implantation of the bridging stent.

[0074] In some specific embodiments, the diameter of the third intermediate coating 231 is D6. Preferably, the ratio of D6 to D4 ranges from 0.5 to 0.9. This ensures that the third intermediate coating 231 of the main body 1 is not squeezed and also facilitates the implantation of the bridging stent. The third intermediate coating 231 can be coaxial or non-coaxial with the bare stent segment 121b. In this embodiment, the central axis of the bare stent segment 121b is closer to the embedded branch 2 than the central axis of the third intermediate coating 231, providing a relatively large operating space for the implantation of the bridging stent.

[0075] In some specific embodiments, the proximal end of the bare stent segment 121b is fixed to the inner side or outer side of the distal end of the proximal main body covering 141 by suturing, bonding, etc., and the distal end of the bare stent segment 121b is fixed to the inner side or outer side of the proximal end of the distal main body covering 142, and the portion of the bare stent segment 121b fixed to the proximal main body covering 141 and the distal main body covering 142 occupies a ratio of 0.1 to 1 of the axial length of the bare stent segment 121b itself, so that the fixation of the bare stent segment 121b can be more stable, thereby ensuring the structural stability of the main body 1.

[0076] In other embodiments, an outer layer coating and / or connecting structures such as an outer layer coating may also be provided along the axial direction of the coated stent 100 on the side of the bare stent segment 121b away from the embedded branch 2. When the coated stent 100 is used for an arch blood vessel, the side of the bare stent segment 121b away from the embedded branch 2 is close to the small bend of the arch blood vessel. The provision of the outer layer coating and / or connecting structures such as an outer layer coating can prevent the bare stent segment 121b from protruding through peaks and troughs when adapting to the curvature of the blood vessel and damaging the inner wall of the blood vessel.

[0077] The stent graft 100 of the above-mentioned embodiment 1 and embodiment 2 both include an embedded branch 2. Figure 13 、 Figure 14 In other embodiments, the stent graft 100 of the present invention may also omit the embedded branch 2, but instead open windows on the intermediate unit 23 to set one or more windows 231 for the bridging stent to communicate with the stent graft 100 through the windows 231. Alternatively, the stent graft 100 of the present invention not only includes an embedded branch 2, but also may be provided with multiple windows 231 on the intermediate unit 23. However, it should be noted that if the stent graft 100 omits the embedded branch 2, the two ends of the intermediate unit 23 need to be sealed as much as possible with the proximal main body coating 141 and the distal main body coating 142, for example, by sealingly connecting the proximal segment 11 through the proximal sealing film 30, and by sealingly connecting the distal segment 13 through the distal sealing film 40. It will be understood by those skilled in the art that whether the bridging stent is connected by other means such as setting an embedded branch 2 or opening windows, it does not affect the above-mentioned technical effects achieved by the stent graft 100 of the present invention.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A stent graft, characterized in that: include: a main body, the main body comprising a proximal segment, a distal segment, and an intermediate segment located between the proximal segment and the distal segment, the intermediate segment comprising an intermediate unit and at least one bare stent segment, the bare stent segment being disposed outside the intermediate unit, and a gap being formed between at least a portion of the bare stent segment and an outer surface of the intermediate unit; The main body has an inner cavity running through the proximal section, the distal section and the middle unit, and the gap is in communication with the inner cavity; The projection of the intermediate unit on a certain cross section of the main body has a first boundary, the projection of the proximal segment on the cross section has a second boundary, the projection of the distal segment on the cross section has a third boundary, and the first boundary is located within the second boundary and within the third boundary; The intermediate unit includes a tubular intermediate segment covering, wherein the inner cavity formed by the intermediate segment covering is in communication with the inner cavity of the proximal segment and the inner cavity of the distal segment; The coated stent also includes an embedded branch, which has an inner cavity. The embedded branch is arranged in the inner cavity of the main body, and the inner cavity of the embedded branch is connected to the gap. The embedded branch includes an embedded stent and a branch coating covering the embedded stent, and the embedded stent and the branch coating are sutured and fixed. The bare stent segment is used for the bridging stent to pass through and communicate with the embedded branch.

2. The stent graft according to claim 1, wherein: The embedded branch includes a proximal tube body correspondingly arranged in the proximal section and a distal tube body correspondingly arranged in the distal section, and the inner cavities of the proximal tube body and the distal tube body are both communicated with the inner cavity of the main body.

3. The stent graft according to claim 2, wherein: The embedded branch also includes a proximal transition section connecting the gap and the proximal tube body, and a distal transition section connecting the gap and the distal tube body. The proximal transition section and the distal transition section are both trumpet-shaped, and the reduced end of the trumpet-shaped proximal transition section faces the proximal end of the main body, and the reduced end of the trumpet-shaped distal transition section faces the distal end of the main body.

4. The stent graft according to claim 1, wherein: The central axis of the bare stent segment is closer to the embedded branch than the central axis of the intermediate unit.

5. A stent graft, characterized in that: include: a main body, the main body comprising a proximal segment, a distal segment, and an intermediate segment located between the proximal segment and the distal segment, the intermediate segment comprising an intermediate unit and at least one bare stent segment, the bare stent segment being disposed outside the intermediate unit, and a gap being formed between at least a portion of the bare stent segment and an outer surface of the intermediate unit; The main body has an inner cavity running through the proximal section, the distal section and the middle unit, and the gap is in communication with the inner cavity; The projection of the intermediate unit on a certain cross section of the main body has a first boundary, the projection of the proximal segment on the cross section has a second boundary, the projection of the distal segment on the cross section has a third boundary, and the first boundary is located within the second boundary and within the third boundary; The intermediate unit includes a tubular intermediate segment covering, wherein the inner cavity formed by the intermediate segment covering is in communication with the inner cavity of the proximal segment and the inner cavity of the distal segment; At least one window is provided on the intermediate unit, and the window communicates with the gap and the inner cavity of the intermediate unit. The bare stent segment is used for allowing the bridging stent to pass through and communicate with the window.

6. The stent graft according to any one of claims 1 to 5, wherein: The intermediate segment covering includes a first intermediate covering and a second intermediate covering connected to the first intermediate covering, and the first intermediate covering and the second intermediate covering enclose and form the inner cavity of the intermediate unit; or, the intermediate segment covering includes a tubular third intermediate covering, and the third intermediate covering is arranged in the inner cavity formed by the bare stent segment and is separated from the bare stent segment.

7. The stent graft according to any one of claims 1 to 5, wherein: The middle section coating covers a portion of the bare stent segment in the circumferential direction, and the portion of the bare stent segment not coated forms an exposed portion, and the gap is formed between the exposed portion and the outer surface of the middle section coating.

8. The stent graft according to any one of claims 1 to 5, wherein: The diameter of the proximal segment is D1, the diameter of the middle segment is D2, and the diameter of the distal segment is D3, wherein D1>D2, D3>D2.

9. The stent graft according to any one of claims 1 to 5, wherein: The intermediate section coating includes a tubular third intermediate coating, which is arranged in the inner cavity formed by the bare stent segment and is separated from the bare stent segment. The bare stent segment includes a plurality of annular waves arranged along the axial direction of the main body. Among the plurality of annular waves, at least two adjacent waves can move relative to each other.

10. The stent graft according to claim 7, wherein: The exposed portion includes at least one pair of adjacent wave crests and wave troughs in the axial direction, which are hooked and connected to each other and can move relatively.

11. The stent graft according to claim 7, wherein: The exposed portion is in an arc shape, and a central angle corresponding to a projection of the exposed portion on the cross section is less than or equal to 120 degrees.

12. The stent graft according to any one of claims 1 to 5, wherein: One end of the middle section covering film is connected to the proximal section via a proximal sealing film, and the other end is connected to the distal section via a distal sealing film.

13. The stent graft according to any one of claims 1 to 5, wherein: The diameter of the bare stent segment is greater than or equal to the diameter of the proximal segment and / or the distal segment.

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