Covered stent

Abstract

This invention provides a covered stent, including a main stent. The surface friction coefficient of the first covering membrane in the proximal and middle sections of the main stent is set to be greater than that of the second covering membrane in the distal section, thereby providing better long-term anchoring and fixation performance in the proximal and middle sections and better long-term blood flow performance in the distal section. Furthermore, a double-embedded stent covering the second covering membrane is disposed in the middle section, which can improve the long-term patency of the middle section while further reducing the volume of the middle section in the compressed delivery state. Moreover, the partial exposure of the first embedded stent can provide better long-term anchoring for other stent implantations, while the integrated design of the second embedded stent and the distal section can improve the long-term flowability within the channel. By designing different covering membranes in different positions and structures on the same stent, different stent segments can exhibit different excellent effects, which is more beneficial to the long-term use of the stent as a whole in vivo.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more particularly to a covered stent. Background Technology

[0002] The iliac arteries include the common iliac artery, external iliac artery, and internal iliac artery. Current techniques for treating iliac artery aneurysms involve endovascular treatment, implanting an iliac artery bifurcation stent and an internal iliac artery covered stent to reconstruct the arterial vessel. Existing iliac artery bifurcation stents typically have two branch channels, one for reconstructing the internal iliac artery and the other for the external iliac artery. Generally, the proximal end of the iliac artery bifurcation stent is used for anchoring to the vessel or connecting to other stents, while the distal end directly reconstructs the external iliac artery channel. The transition segment between the proximal and distal ends has a branch interface for connecting the internal iliac artery covered stent. Current techniques generally use PTFE or PET as the covering material to fabricate iliac artery bifurcation stents; however, PTFE is difficult to integrally mold at the bifurcation transition segment, while PET has poor long-term patency rates. Intravascular patency is affected by the stent covering material and the lumen size. Summary of the Invention

[0003] Therefore, it is necessary to provide a new covered stent that can exhibit different superior effects in different stent segments through different combinations of coverings, which is more beneficial for the long-term use of the stent as a whole in vivo.

[0004] A covered stent includes a main stent having a tubular body, the main stent comprising, axially, a proximal segment, an intermediate segment, and a distal segment, wherein the diameter of the distal segment is smaller than the diameter of either the proximal segment or the intermediate segment; the distal end of the intermediate segment includes a distal opening, the distal segment being connected to the intermediate segment via the distal opening and only partially covering the distal opening; the surfaces of the proximal segment and the intermediate segment are covered with a first coating, and the surface of the distal segment is covered with a second coating, wherein the surface friction coefficient of the second coating is less than or equal to the surface friction coefficient of the first coating.

[0005] In one embodiment, both the proximal segment and the distal segment include a plurality of first wave coils spaced apart along the axial direction, and the inner cavity of the intermediate segment is connected to an embedded support, the surface of which is provided with a second coating.

[0006] In one embodiment, the embedded support includes a first embedded support and a second embedded support, wherein the first embedded support is radially offset from the distal segment, and the second embedded support is connected to the distal segment.

[0007] In one embodiment, the intermediate section includes a plurality of second waverings spaced apart along the axial direction, wherein the second waverings are continuous annular waverings or have openings at least at the position where they overlap with the first embedded bracket in the circumferential direction.

[0008] In one embodiment, the diameter of the second embedded bracket is equal to the diameter of the distal segment, and the second embedded bracket and the distal segment are integrally formed or formed separately and then connected together.

[0009] In one embodiment, the second coating includes an outer surface coating and an inner surface coating, which are fused together by thermoforming. The second embedded support includes a support frame, and the support frame and the first wave ring of the distal segment are both disposed between the outer surface coating and the inner surface coating.

[0010] In one embodiment, the outer surface coating only partially covers the outer walls of the first embedded bracket and the second embedded bracket, or the inner surface coating only partially covers the inner wall of the first embedded bracket.

[0011] In one embodiment, both the outer surface coating and the inner surface coating are formed by melting and molding multiple sub-films, wherein the number of sub-films in the inner surface coating is greater than or equal to the number of sub-films in the outer surface coating.

[0012] In one embodiment, the total number of sub-membranes in the distal segment is greater than or equal to the total number of sub-membranes in the second embedded scaffold.

[0013] In one embodiment, the distal opening of the intermediate segment is flush with the distal ports of the first embedded bracket and the second embedded bracket, and the distal ports of the first embedded bracket and the second embedded bracket are mutually opposite beveled openings.

[0014] The beneficial effects of this invention are as follows: Compared with the prior art, this invention provides a covered stent, including a main stent with a tubular body. The surface friction coefficient of the first covering in the proximal and middle sections of the main stent is set to be greater than that of the second covering in the distal section, thereby providing better long-term anchoring and fixation performance in the proximal and middle sections, and better long-term blood flow performance in the distal section. Furthermore, a double-embedded stent covering the second covering is provided in the middle section, which can improve the long-term patency of the middle section while further reducing the volume of the middle section in the compressed delivery state. Moreover, the partial exposure of the first embedded stent located in the internal iliac canal can provide better long-term anchoring of the internal iliac covered stent, while the integrated design of the second embedded stent and the distal section can further improve the long-term flowability in the external iliac canal. Through the design of different coverings in different positions and structures on the same stent, different stent segments exhibit different excellent effects, which is more beneficial to the long-term use of the stent as a whole in vivo. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the overall structure of the film-coated stent in Embodiment 1 of the present invention;

[0016] Figure 2 This is a side view of a second wave ring in the middle section of the film-coated support in one embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of an opening structure provided in the second wave coil of the middle section in another embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of the overall internal cross-sectional structure of the membrane-covered stent in Embodiment 1 of the present invention;

[0019] Figure 5 For the present invention Figure 4 A magnified schematic diagram of the structure at position A in the middle;

[0020] Figure 6 This is a schematic diagram of the structure without a corrugated ring in the middle section of the film-coated support in Embodiment 2 of the present invention;

[0021] Figure 7 This is a schematic diagram of the radial cross-sectional structure of the second membrane covering of the embedded support in Embodiment 2 of the present invention;

[0022] Figure 8 This is a schematic diagram showing the coating portion on the outer surface of the embedded bracket in one embodiment of the present invention;

[0023] Figure 9 This is a schematic diagram showing the coating on the inner surface of the embedded bracket in Embodiment 4 of the present invention;

[0024] Figure 10 This is a schematic cross-sectional view of the multilayer sub-film structure of the second coating in Embodiments 2 to 4 of the present invention;

[0025] Figure 11 This is a schematic diagram of the double oblique opening structure at the distal end of the middle section in Embodiment 4 of the present invention;

[0026] Figure 12 This is a schematic diagram of the structure in Embodiment 5 of the present invention, in which the proximal end of the distal segment has an extension portion;

[0027] Figure 13 For the present invention Figure 12 Enlarged sectional view of the structure at position B in the middle;

[0028] Figure 14 This is a schematic diagram of the structure when the extension is a skirt-shaped film in Embodiment 5 of the present invention;

[0029] Figure 15 For the present invention Figure 14 A magnified schematic diagram of the structure at position C in the middle;

[0030] Figure 16 This is a schematic diagram of a ring-shaped spring coil structure for the connector in Embodiment 5 of the present invention;

[0031] Figure 17 This is a cross-sectional schematic diagram of the connection structure between the connector and the exposed wave crest of the near-end wave ring in Embodiment Six of the present invention;

[0032] Figure 18 For the present invention Figure 17 A magnified schematic diagram of the structure at position D in the middle;

[0033] Figure 19 This is a schematic diagram of the connecting sleeve structure for the near-end wave coil in Embodiment Six of the present invention;

[0034] Figure 20 For the present invention Figure 19 A magnified schematic diagram of the structure at position E in the middle;

[0035] Figure 21 This is a schematic diagram of the connection structure between the first mating component and the second mating component in Embodiment Six of the present invention;

[0036] Figure 22 This is a schematic diagram of the structure of the first mating component in Embodiment Six of the present invention;

[0037] Figure 23 This is a schematic diagram of the second mating component in Embodiment Six of the present invention. Detailed Implementation

[0038] To better understand the concept of this application, the implementation methods of this application will be described in detail below with reference to the accompanying drawings. The following specific embodiments are only some embodiments of this application and are not intended to limit this application.

[0039] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0040] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0041] To more clearly describe the structure of this application, the terms "proximal" and "distal" are used here as conventional terms in the field of interventional medicine. Specifically, "distal" refers to the end of the blood vessel furthest from the heart, and "proximal" refers to the end of the blood vessel closest to the heart; "axial" refers to its length direction, and "radial" refers to the direction perpendicular to the "axial" direction; "upper end" and "lower end" refer to two relatively distant ends, and when one end is defined as "upper end", the other distant end is "lower end".

[0042] Example 1:

[0043] This invention provides a film-coated stent 100, please refer to [link / reference]. Figure 1 and Figure 2The covered stent 100 typically consists of a metal skeleton and a covering material. The metal skeleton can be designed with a Z-shaped wave or a woven mesh. The covering material has a certain blood flow isolation capability and is combined with the metal skeleton through methods such as pressure heating and suturing to form a complete covered stent 100. In this invention, the covered stent 100 is typically used in arteries and their branches in the human body. However, this does not mean that the covered stent 100 can only be applied to arteries. Other vascular locations in the human body with different types of structures and environments may also be suitable for the covered stent 100. The proximal end of the covered stent 100 is generally placed in the common iliac artery or connected to an abdominal aortic stent, and the lumen diameter is generally matched to the diameter of the common iliac artery. In this embodiment, the covered stent 100 includes a main stent with a tubular body. The main stent, along its axial length from proximal to distal, includes a proximal segment 1, a middle segment 2, and a distal segment 3. The proximal segment 1 is typically used to provide overall vascular anchoring, anchored within the common iliac artery or abdominal aorta stent, and receives blood. The proximal end of the middle segment 2 connects to the proximal segment 1, and the distal end connects to the distal segment 3. The middle segment 2 is typically positioned as a blood diversion point, spatially divided into an internal iliac channel portion and an external iliac channel portion depending on the blood flow direction. The internal iliac channel portion typically uses an internal iliac covered stent to drain a portion of the blood flowing through the middle segment 2 to the internal iliac vessel portion of the body. After the covered stent 100 is implanted and released into the body's blood vessels, the distal segment 3 is typically located within the external iliac vessel, used to drain a portion of the blood flowing through the middle segment 2 to the external iliac vessel portion of the body. The distal segment 3 has a smaller diameter than the proximal segment 1 and the intermediate segment 2. This design allows the distal segment 3 to be better positioned within the external iliac vessels during implantation and to better adapt to the morphology of the external iliac vessels. Please refer to [link to relevant documentation]. Figure 1 and Figure 2The distal end of the intermediate segment 2 includes a distal opening 22, which includes an opening portion for implantation of an internal iliac stent graft and a portion for proximal connection with the distal segment 3. The distal segment 3 is connected to the distal opening 22 and only partially covers it, thus allowing the portion of the distal opening 22 not connected to the distal segment 3 to be used for implantation of the internal iliac stent graft. The surfaces of the proximal segment 1 and the intermediate segment 2 are covered with a first covering 11, and the surface of the distal segment 3 is covered with a second covering 31. The surface friction coefficient of the second covering 31 is less than or equal to that of the first covering 11. Here, since the intermediate segment 2 and the proximal segment 1 are typically covered... The stent 100 is mainly anchored to the blood vessel. The anchoring force of the covered stent 100 depends first on the radial elastic force after the stent expands, and second on the frictional force along the length of the stent. Therefore, the first covering 11 covering the middle segment 2 and the proximal segment 1 is provided with a large surface friction force, so that after the covered stent 100 expands in the blood vessel, the proximal segment 1 and the middle segment 2 are tightly attached to and anchored to the inner wall of the blood vessel by the elastic force of the stent itself. At this time, since the first covering 11 has a large surface friction force, the frictional force between the stent and the blood vessel wall can be further increased, making the stent anchoring more stable. On the other hand, because the surface of the first cover 11 has good surface friction, blood can stay on the surface of the first cover 11 better when flowing over it, thereby promoting surface thrombosis and endothelialization of the first cover 11. Surface thrombosis and endothelialization increase the connection between the first cover 11 and the inner wall of the blood vessel, thereby further increasing the long-term anchoring force between the proximal segment 1 and the middle segment 2 of the covered stent 100 and the blood vessel. At the same time, the middle segment 2 also uses the first cover 11 with greater surface friction, which makes it more difficult for the internal iliac covered stent to slip out after it is implanted into the lumen of the middle segment 2 through the opening, resulting in better anchoring force and stability after implantation. The distal segment 3 is usually located in the external iliac vessels after the covered stent 100 is implanted. The diameter of the external iliac vessels is usually smaller than that of the common iliac vessels where the proximal segment 1 and the intermediate segment 2 are located. If they are blocked, it will lead to incalculable consequences. Therefore, maintaining the patency of blood flow in the external iliac vessels is essential. By setting a relatively low surface friction on the surface of the second covered stent 31 located in the external iliac vessels, the surface of the stent in the distal segment 3 can have a smoother surface, preventing blood from staying on the stent surface, thereby maintaining good long-term patency and ensuring the patency of blood flow in the external iliac vessels.

[0044] Please refer to Figure 2The surface friction of the first coating 11 and the second coating 31 in this application can be changed by the different weaving structure, porosity or coating material of the coating. In this embodiment, the first coating 11 and the second coating 31 are formed by using different coating materials. Preferably, the first coating 11 is made of PET material and the second coating 31 is made of ePTFE material.

[0045] In this embodiment, please refer to Figure 1 and Figure 2 The proximal segment 1 and distal segment 3 include multiple first wave coils 12 spaced apart along their axial length, while the intermediate segment 2 includes multiple second wave coils 21 spaced apart along the axial direction. The first wave coils 12 and second wave coils 21 are formed by continuous bending of metal wires and connecting them end to end to form an annular wave coil structure, forming multiple peaks and troughs in the axial direction. The first wave coils 12 provide radial elasticity to the proximal segment 1 and distal segment 3, and the second wave coils 21 provide radial elasticity to the intermediate segment 2, thereby providing anchoring force in the blood vessel and supporting force to maintain the lumen of the covered stent 100 when it is implanted into the blood vessel.

[0046] In this embodiment, please refer to Figure 3 and Figure 4 In order to make the blood diversion within the intermediate segment 2 more direct and stable, the inner cavity of the intermediate segment 2 can be connected to an embedded stent 4. The embedded stent 42 can be installed only in the part of the intermediate segment 2 that is offset from the distal segment 3 in the radial direction. At this time, the proximal port of the first embedded stent 42 is connected to the proximal segment 1, and the distal port is connected to the opening of the distal opening 22 of the intermediate segment 2 for the implantation of the internal iliac stent graft. When the internal iliac stent graft is implanted into the intermediate segment 2, it is directly implanted into the inner cavity of the first embedded stent 42. The first embedded stent 42 creates a tubular anchoring space with a completely encapsulated structure within the lumen of the middle segment 2. This ensures that when the internal iliac stent is implanted, the entire circumferential direction of the implanted portion has anchorable positions, thereby increasing the anchoring force and stability of the internal iliac stent. Furthermore, it prevents the implanted portion of the internal iliac stent from swaying to the external iliac passage due to insufficient anchoring force and blood flow, thus blocking blood flow to the distal segment 3 and affecting the blood flow to the external iliac vessels. In another embodiment, in order to reduce the radial compression volume of the intermediate segment 2 after compression, the second wave ring 21 may have an opening or break at least at the position where it overlaps with the first embedded stent 42 in the circumferential direction, and may only include one layer of the first covering 11. With this configuration, the intermediate segment 2 can take into account the enhanced anchoring effect of the first embedded stent 42 on the iliac internal covering stent, while avoiding the formation of a large compression volume in the intermediate segment 2 of the covering stent 100 during compression delivery due to the addition of the first embedded stent 42. The first embedded stent 42 may be provided in the intermediate segment 2 by stitching or bonding.

[0047] In other embodiments, please continue to refer to Figure 4 and Figure 5 The embedded stent 4 may include a first embedded stent 42 and a second embedded stent 41 arranged radially side by side within the intermediate segment 2. The proximal ports of both the first embedded stent 42 and the second embedded stent 41 are connected to the proximal segment 1. The first embedded stent 42 is radially offset from the distal segment 3 of the intermediate segment 2, and its distal port is connected to the opening portion of the distal opening 22 of the intermediate segment 2 for implantation of the internal iliac stent graft. The second embedded stent 41 is radially coaxially arranged with the distal segment 3 of the intermediate segment 2, and its distal port is connected to the proximal end of the distal segment 3. In this way, the internal iliac passage portion and the external iliac passage portion of the intermediate segment 2 are isolated by the first embedded stent 42 and the second embedded stent 41 to form two relatively independent channels. This allows the blood flowing out of the proximal segment 1 to form a shunt state in advance. At the same time, the first embedded stent 42 can increase the anchoring force and anchoring stability of the internal iliac stent graft, and the second embedded stent 41 can isolate the interference of the first embedded stent 42 on the external iliac passage portion, ensuring the passage of blood in the external iliac passage portion. The first embedded stent 42 and the second embedded stent 41 are provided with a second covering 31 on their surfaces. This arrangement ensures that the outer wall of the intermediate segment 2, which is separated from the blood vessel wall, is covered by the first covering 11, which has high surface friction, while the inner wall is covered by the second covering 31 provided by the first and second embedded stents 42 and 41. This creates a structure with good long-term anchoring force and stability on the outer wall and a structure with good long-term blood flow permeability on the inner wall. This results in the intermediate segment 2 of the covered stent 100 exhibiting different long-term characteristics on the inner and outer walls, achieving better long-term performance of the covered stent 100. Furthermore, using the second covering 31 as the surface covering for the first and second embedded stents 42 and 41 allows for the division of blood channels in the intermediate segment 2 by the first and second embedded stents 42 and 41, while minimizing the impact of the covering on the compressed volume of the intermediate segment 2.

[0048] Example 2:

[0049] In this embodiment, please refer to Figure 5 and Figure 6The proximal segment 1 and distal segment 3 of the covered stent 100 are largely the same as those in Embodiment 1, except that the intermediate segment 2 does not have a second wave coil 21, but only a first covering 11. With this configuration, the inner cavity of the intermediate segment 2 simultaneously houses a first embedded stent 42 and a second embedded stent 41. The first embedded stent 42 and the second embedded stent 41 provide support for the intermediate segment 2. The outer wall of the intermediate segment 2 is only provided with the first covering 11, ensuring that, supported by the first embedded stent 42 and the second embedded stent 41, the first covering 11 adheres to the vessel wall after the intermediate segment 2 is implanted into the blood vessel. This ensures the frictional force of the covered stent 100 when anchoring between the intermediate segment 2 and the vessel wall, thus ensuring anchorage. Furthermore, the first... The higher surface friction of the first covering 11 compared to the second covering 31 allows for better thrombosis and endothelialization of the outer wall of the intermediate segment 2 with the vessel wall, resulting in long-term stable anchoring. Simultaneously, the intermediate segment 2, with the second wave coil 21 removed and incorporating the first and second embedded stents 42 and 41, achieves independent separation of the internal and external iliac channels of the intermediate segment 2 by the first and second embedded stents 42 and 41, without sacrificing radial support. Furthermore, when the covered stent 100 is in a compressed delivery state, the compressed volume of the intermediate segment 2 does not increase due to the absence of the second wave coil 21 and the presence of only the bare membrane, which is beneficial for the compressed delivery of the covered stent 100 within the vessel.

[0050] In this embodiment, please refer to Figures 7-10 The second coating 31 includes an outer surface coating 312 and an inner surface coating 311, which are fused together by hot pressing. The first embedded support 42 and the second embedded support 41 include a support frame 411, which can be a mesh support frame 411 with multiple mesh openings. In this design, the first wave coil 12 of both the support frame 411 and the distal segment 3 is positioned between the outer surface covering and the inner surface covering 311. This arrangement, embedding the support frame 411 and the first wave coil 12 of the distal segment 3 within the outer and inner surface coverings 312 and 311, prevents the support frame 411 from directly contacting the blood, thus avoiding long-term effects of blood on the support frame 411. Furthermore, the low surface friction of the second covering 31 reduces blood migration across the inner surfaces of the first and second embedded stents 42 and 41, thereby reducing thrombosis and endothelialization on the inner surfaces of the first and second embedded stents 42 and 41, ensuring good blood flow. Please refer to further details. Figure 10During the molding process, both the outer surface coating 312 and the inner surface coating 311 are formed by melting and molding multiple sub-films 3101. After the multiple sub-films 3101 are stacked radially, they are formed into a complete inner surface coating 311 or outer surface coating 312 by hot melting. Therefore, the number of sub-films 3101 used can determine the overall thickness of the inner surface coating 311 and the outer surface coating 312 after molding. After the inner surface coating 311 and the outer surface coating 312 of different thicknesses are combined with the support frame 411 and the first wave ring 12 of the distal segment 3, the degree of protrusion of the support frame 411 and the first wave ring 12 of the distal segment 3 on the surface of the inner surface coating 311 and the outer surface coating 312 is different, resulting in different degrees of surface smoothness.

[0051] In one embodiment, please continue reading Figure 10 The outer walls of the first embedded stent 42, the second embedded stent 41, and the distal segment 3 are used for direct or indirect attachment and anchoring to the vessel wall. Therefore, in order to enable the outer wall of the stent to provide better anchoring performance, the number of sub-membrane 3101 layers of the inner surface covering 311 can be set to be greater than or equal to the number of sub-membrane 3101 layers of the outer surface covering 312. This allows different sub-membrane 3101 layers of the second covering 31 to exhibit different structural characteristics on the inner and outer walls of the first embedded stent 42, the second embedded stent 41, and the distal segment 3, so as to better achieve different long-term effects. With fewer sub-membrane 3101 layers in the outer surface coating 312, the overall thickness of the outer surface coating 312 decreases after molding. Consequently, the protrusions of the embedded stent 4, the second embedded stent 41, the supporting framework 411 of the distal segment 3, and the first wave coil 12 on the outer wall are more pronounced. Therefore, when the embedded stent 4, the second embedded stent 41, the inner wall of the intermediate segment 2, and the distal segment 3 are anchored to the vessel wall, the reduced smoothness of the outer wall surface due to the protrusions allows for better surface friction, thereby increasing the anchoring force. The inner surface coating 311 has more sub-membrane 3101 layers than the outer surface coating 312. When the inner surface coating 311 is fully formed, the supporting skeleton 411 and the first corrugated coil 12 do not protrude from the inner wall, thus maintaining a good surface smoothness. As a result, since the second embedded stent 41 and the distal segment 3 jointly drain blood to the external iliac vessels, the increased thickness of the inner surface coating 311 can maintain a good surface smoothness, thereby improving the long-term patency of blood flow. Preferably, the inner surface coating 311 and the outer surface coating 312 are typically set to 3-8 layers of sub-membrane 3101. In this embodiment, in order to make the outer and inner walls of the first embedded stent 42, the second embedded stent 41, and the distal segment 3 exhibit different long-term effects, the inner surface coating 311 can be set to 6 layers of sub-membrane 3101, while the outer surface coating 312 can be set to 3 layers of sub-membrane 3101, all of which are made of ePTFE material.

[0052] Example 3:

[0053] In this embodiment, please refer to Figures 8-10 The structures of the proximal segment 1 and distal segment 3 of the covered stent 100, as well as the structures of the intermediate segment 2 and the embedded stent 4, are largely the same as those in Embodiments 1 and 2. The difference is that, in order to further reduce the impact of the first embedded stent 42 and the second embedded stent 41 on the volume of the intermediate segment 2 of the covered stent 100 after compression, the radial thickness of the second covering membrane 31 of the first embedded stent 42 or the second embedded stent 41 can be set to be less than the radial thickness of the second covering membrane 31 of the distal segment 3. Here, since the outer walls of the first embedded stent 42 and the second embedded stent 41 are at least covered with the first covering membrane 11, the second covering membrane 31 mainly plays the role of improving the long-term patency of blood flow in the internal iliac channel and the external iliac channel of the intermediate segment 2. Therefore, as long as the inner wall surfaces of the first embedded stent 42 and the second embedded stent 41 are covered with at least one sub-membrane 3101, the long-term patency can be better than that of the inner cavity where the first covering membrane 11 is the inner wall surface. Therefore, minimizing the total number of sub-membranes 3101 in the second covering 31 of the first embedded stent 42 and / or the second embedded stent 41, and reducing the thickness of the second covering 31, ensures long-term blood patency in the intermediate segment 2 while minimizing the volume of the first embedded stent 42 and the second embedded stent 41 after compression in the intermediate segment 2. This reduces the radial volume of the covered stent 100 after overall compression in the intermediate segment 2, facilitating sheathing of the covered stent 100 and ensuring the flexibility of the delivery sheath in the intermediate segment 2 during delivery. Conversely, providing a relatively larger total number of sub-membranes 3101 in the distal segment 3 avoids the problem of the second covering 31 rupturing during long-term use due to an insufficient number and thickness of sub-membranes 3101. Furthermore, it allows for the placement of more layers of sub-membranes 3101 on the inner surface of the distal segment 3, ensuring the surface smoothness of the inner wall of the distal segment 3 and improving long-term blood patency. In one embodiment, the total number of sub-films 3101 of the second covering film 31 of the first embedded support 42 and the second embedded support 41 is set to be less than the total number of sub-films 3101 of the distal segment 3.

[0054] In one embodiment, since the intermediate segment 2 of the covered stent 100 contains a first embedded stent 42 and a second embedded stent 41, and the proximal and distal ports of the first embedded stent 42 and the second embedded stent 41 are connected to the proximal opening and the distal opening 22 of the intermediate segment 2 by suturing or adhesive bonding, blood typically does not pass through the second covering 31 of the first embedded stent 42 and the second embedded stent 41 and the first covering 11 of the intermediate segment 2. The first covering 11 can serve as an outer protective covering for the first embedded stent 42 and the second embedded stent 41 to provide further blood barrier protection. Therefore, please refer to... Figure 8The outer surface covering 312 of the second covering 31 of the first embedded bracket 42 and the second embedded bracket 41 can be configured to only partially cover their outer walls. In this embodiment, the partially configured outer surface covering 312 can be configured only on the outer walls of the first embedded bracket 42 and the second embedded bracket 41 along the support frame 411, covering only part of the support frame 411. That is, when viewed from a radial cross section, the outer surface covering 312 surrounds and covers the part of the support frame 411 near the outer wall, and then connects with the inner surface covering 311. The part without the support frame 411 only includes the inner surface covering 311. This configuration reduces the total amount of covering material on the outer surface of the second covering 31, resulting in a smaller volume of the second covering 31 after compression of the first embedded stent 42 and the second embedded stent 41 in the intermediate segment 2. This makes it easier to sheath the covered stent 100. At the same time, this covering configuration allows the support skeleton 411 of the first embedded stent 42 and the second embedded stent 41 to protrude on the outer wall, which is more beneficial when the intermediate segment 2 is released and deployed in the blood vessel. The first embedded stent 42 and the second embedded stent 41 compress the first covering 11 to adhere to the blood vessel wall, increasing the anchoring force.

[0055] In another embodiment, the partially configured outer surface covering 312 can be configured such that the supporting skeleton 411 of the outer wall is partially exposed in the space formed between the first covering 11 and the second covering 31. With this configuration, firstly, the partial covering reduces the total amount of covering on the outer surface of the second covering 31, thereby reducing the volume of the second covering 31 after compression of the first embedded stent 42 and the second embedded stent 41 of the intermediate segment 2, making it easier to sheath the covered stent 100; secondly, the partially exposed supporting skeleton 411 reduces the constraint of the outer surface covering 312 on the portion of the supporting skeleton 411 on the outer wall, thereby having better radial expansion performance, which is more beneficial when the intermediate segment 2 is released and deployed in the blood vessel, the first embedded stent 42 and the second embedded stent 41 squeeze the first covering 11 to adhere to the blood vessel wall, increasing the anchoring force.

[0056] Example 4:

[0057] In this embodiment, please refer to Figure 9The structures of the proximal segment 1 and distal segment 3 of the covered stent 100, as well as the structures of the intermediate segment 2 and the embedded stent 4, are largely the same as in Embodiment 3. The difference is that the inner surface covering 311 of the first embedded stent 42 can be set to partially cover the inner wall of the first embedded stent 42, that is, the supporting skeleton 411 of the first embedded stent 42 is partially exposed on the inner wall of the first embedded stent 42. Since after the first embedded stent 42 is implanted into a human blood vessel, an internal iliac covered stent is usually implanted to reconstruct the internal iliac branch. The exposure of the supporting skeleton 411 allows the supporting skeleton 411 to directly abut and support the implanted internal iliac covered stent. Since the supporting skeleton 411 has a greater surface friction than the second covering 31, the exposed supporting skeleton 411 can provide better surface friction to the implanted internal iliac covered stent, so as to ensure the long-term stability of the internal iliac covered stent after implantation and avoid slippage. Furthermore, the exposed inner wall of the support skeleton 411, under the flushing effect of long-term inflowing blood, can form thrombosis and surface endothelialization between the first embedded stent 42 and the iliac internal covered stent, thereby enhancing the long-term anchoring of the iliac internal covered stent and the first embedded stent 42. The partial placement of the second cover 31 on the inner surface of the second cover 31 also reduces the total amount of the second cover 31 on the inner surface of the second cover 31, resulting in a smaller volume of the second cover 31 after compression of the first embedded stent 42 in the middle segment 2, thus making the covered stent 100 easier to sheath.

[0058] In one embodiment, please continue reading Figure 9 The inner surface coating 311 of the part is provided with multiple annular coatings. The multiple annular coatings are spaced apart along the axial direction on the inner wall of the first embedded bracket 42, and gaps are left between the spaced annular coatings, so that the support frame 411 is exposed from the gaps to form an exposed part. Preferably, since the support frame 411 is a mesh support frame 411 in this embodiment, the spacing of the adjacent annular coatings is located at the mesh intersection of the support frame 411. With this arrangement, the exposure at the mesh intersection of the support frame 411 can also reduce the restraint at the intersection when the first embedded bracket 42 is bent, compressed or expanded by the coating bracket 100, so as to have better conformability and better response performance when the middle section 2 is bent, compressed or expanded.

[0059] In another embodiment (not shown in the figure), the partially formed inner surface covering 311 is provided with multiple slots or openings. The support frame 411 is exposed on the inner wall of the first embedded stent 42 through these slots or openings. Preferably, the multiple slots or openings are respectively located at the intersections of the mesh of the mesh support frame 411. This arrangement creates a distributed, multi-point high-friction position along the circumference of the inner wall of the first embedded stent 42, resulting in a uniform and multi-point distribution of the anchoring force of the implanted iliac intracorporeal stent, which further enhances long-term anchoring performance. The exposure at the intersections of the mesh of the support frame 411 also reduces the constraint at the intersections when the first embedded stent 42 is bent, compressed, or expanded by the covered stent 100, resulting in better compliance and improved response performance when the middle segment 2 is bent, compressed, or expanded. The slots or openings can be any one or a combination of square, circular, triangular, or polygonal shapes.

[0060] In one embodiment, to ensure good long-term patency of the external iliac channel portion and distal segment 3 of the second embedded stent 41 separated within the intermediate segment 2, the second embedded stent 41 and the distal segment 3 are coaxial and have the same diameter. This arrangement avoids the obstruction of blood flow between the two stent segments due to a difference in diameter. Furthermore, to further improve the connection between the second embedded stent 41 and the distal segment 3, the distal end of the second embedded stent 41 and the proximal end of the distal segment 3 are butted and sutured together to form a unified conduit, thereby reducing endoleak and improving the long-term patency of blood flow between the two stent segments.

[0061] In another embodiment, to achieve a high degree of smoothness on the inner wall surfaces of the second embedded support 41 and the distal segment 3, please refer to... Figure 5 The second embedded stent 41 and the distal segment 3 are integrally formed into a single stent. Here, integral forming means that the supporting skeleton 411 of the second embedded stent 41 and the first wave 12 of the distal segment 3 are formed into a single stent by heat fusion through a continuous and complete inner surface coating 311 and outer surface coating 312. The single stent can ensure that the inner wall is continuous and the surface is smooth, and there are no sutures or other structures that affect the surface smoothness, thereby improving the long-term patency of blood flow between the two stent segments.

[0062] In this embodiment, please refer to Figure 11To ensure unobstructed blood flow at the proximal and distal ends of the first embedded stent 42 and the second embedded stent 41, and to facilitate easier and faster insertion of the internal iliac stent graft at the distal end of the first embedded stent 42, the distal ends of the first embedded stent 42 and the second embedded stent 41 are at least set as mutually opposing oblique openings 221, forming a V-shaped double oblique opening 221 structure. The design of the oblique opening 221 can maximize the size of the opening without increasing the original stent tube diameter, thereby facilitating the entry and exit of liquids or other medical devices or implants. Correspondingly, the distal opening 22 of the middle section 2 is flush with the distal ends of the first embedded stent 42 and the second embedded stent 41 to accommodate the double oblique opening 221 structure.

[0063] Example 5:

[0064] In this embodiment, please refer to Figure 5 and Figure 13 The structures of the proximal segment 1 and the intermediate segment 2 of the covered stent 100 are largely the same as those in Embodiments 1 to 4. The difference lies in that, after the distal segment 3 is integrally formed with the second embedded stent 41, in order to ensure better connection stability with the intermediate segment 2 of the main stent and to guarantee the integrity of the stent, the distal segment 3 is simultaneously connected to the distal opening 22 and the second embedded stent 41. Here, the intermediate segment 2 can be connected to the distal segment 3 by suturing or bonding. Bonding is not conducive to long-term stability, while suturing provides better connection stability in the long term. However, since the distal segment 3 uses a PTFE membrane to pursue better long-term patency, the tensile strength of the PTFE membrane is low. After suturing, the suture hole may enlarge or tear under long-term axial force on the stent, resulting in bleeding at the suture site. Therefore, in this embodiment, please refer to... Figure 13 This ensures that, after connection, at least the inner surfaces of the distal segment 3 and the second embedded support 41 are integral continuous surfaces, meaning that the suture holes of the intermediate segment 2 and the distal segment 3 are not formed on the integrally formed inner surfaces of the distal segment 3 and the second embedded support 41. Specifically, as mentioned in the above embodiments, the distal segment 3 includes a plurality of first corrugated coils 12 spaced apart along the axial direction, and the second coating 31 includes an outer surface coating 312 and an inner surface coating 311, with the outer surface coating 312 and the inner surface coating 311 covering the first corrugated coils. The outer and inner surfaces of the 12 are fused together by hot pressing. The inner surface film 311 of the distal segment 3 is integrally and continuously formed with the inner surface film 311 of the first embedded support 42. The distal opening 22 of the middle segment 2 is only connected to the distal segment 3 at other locations except for the inner surface film 311. Therefore, after connection, in the event of long-term deformation, at least the deformation will not extend into the inner surface film 311 and damage the smoothness of the flow from the second embedded support 41 to the distal segment 3 and the airtightness of the channel.

[0065] In this embodiment, not shown in the figure, the distal opening 22 can be connected to the proximal end of the outer surface coating 312. Here, since the middle section 2 is made of PET film, the PET film has good tensile strength and can effectively resist long-term axial tensile deformation. Connecting the distal opening 22 of the middle section 2 to the proximal end of the outer surface coating 312 can provide a certain resistance to axial elongation at the connection point. The connection point of the distal section 3 is on the outer surface coating 312. Even if the coating is deformed and stretched under long-term blood impact, it will not affect the overall surface continuity and unobstructedness of the inner surface coating 311.

[0066] For details, please continue reading. Figure 13 The distal opening 22 is connected to the proximal end of the outer surface coating 312 via the connector 5. Here, in order to further reduce the impact of deformation of the connection between the distal opening 22 and the outer surface coating 312 under long-term blood impact as little as possible, the outer surface coating 312 of the distal segment 3 includes a connecting portion located at the proximal end. The connecting portion extends at least partially radially away from the inner surface coating 311 to form an extension 313. The connector 5 is connected to the extension 313. A connecting portion is further provided on the outer surface coating 312 of the distal segment 3 for connection with the connector 5. So that when the connector 5 is subjected to axial impact force, even if the connection with the connecting portion deforms, it will not spread to the outer surface coating 312. Thus, neither the inner surface coating 311 nor the outer surface coating 312 will produce a connection gap after the distal segment 3 is connected to the middle segment 2. Under axial force, the expansion or tearing of the connection hole occurs on the connecting portion instead of directly on the inner surface coating 311 and the outer surface coating 312.

[0067] In one embodiment, see Figure 12 and Figure 13 The extension 313 can be a thickened film 3131 that protrudes from the outer surface film 312 away from the inner surface film 311. Here, the number of sub-films 3101 at the position of the thickened film 3131 on the outer surface film 312 is greater than the number of sub-films 3101 at other positions on the outer surface film 312. During molding, the thickened film 3131 is additionally covered with more sub-films 3101 at the position of the connecting part on the outer surface of the second film 31 of the original distal segment 3, thereby forming the extension 313. When the connector 5 is connected, it passes through the thickened film 3131 to achieve connection with the outer surface film 312. With such a connection, even if deformation occurs between the connecting part and the thickened film 3131 under axial force in the future, the deformation will not extend to the second film 31 of the distal segment 3, thereby preventing problems such as blood leakage from the second film 31.

[0068] In another embodiment, please refer to Figure 14 and Figure 15The extension 313 can be a skirt-shaped cover 3132 extending away from the inner surface cover 311 and away from the outer surface cover 312. Here, when the skirt-shaped cover 3132 is formed, an additional second cover 31 is attached to the outer surface of the original second cover 31 of the distal segment 3 at the location of the connecting portion. The distal end of the skirt-shaped cover 3132 is connected to the connecting portion, and after the connection, the other positions are separated from the outer surface cover 312 and extend, thereby forming the extension 313. When the connector 5 is connected, it passes through the skirt-shaped cover 3132 to achieve the connection with the outer surface cover 312. With such a connection, even if deformation occurs between the connecting portion and the skirt-shaped cover 3132 under axial force in the long term, the deformation will not extend to the second cover 31 of the distal segment 3, thereby preventing problems such as blood leakage from the second cover 31.

[0069] In this embodiment, please refer to Figure 13 The connector 5 can be a suture, which connects the distal opening 22 of the middle section 2 and the connecting part together by suturing.

[0070] In one embodiment, see Figure 15 The connector 5 can also be a plurality of connecting rings spaced apart circumferentially along the connecting part. The middle section 2 is close to the distal opening 22 and has a plurality of connecting holes spaced apart circumferentially connected to the distal section 3. The plurality of connecting rings pass through the connecting holes and connect to the connecting part of the distal section 3. The connecting ring can be a ring-shaped polymer coil or a ring-shaped metal coil. The setting of the connecting ring can also increase the anchoring area between the covered stent 100 and the blood vessel wall after the covered stent 100 is implanted into the blood vessel, thereby increasing the stability of the anchoring.

[0071] In another embodiment, please refer to Figure 16 The connector 5 can also be a continuous annular spring coil along the circumference of the connecting part. The middle section 2 is close to the distal opening 22, and multiple connecting holes are spaced apart in the circumferential direction connecting with the distal section 3. The annular spring coil passes through multiple connecting holes and connects with the connecting part of the distal section 3. The annular spring coil can be a polymer coil spring or a metal coil spring. When it is set as a metal coil spring, it can be a metal material with imaging function such as tantalum wire, thereby forming the alignment and indication of the bifurcation position of the stent and the blood vessel in the body. The setting of the annular spring coil can also increase the anchoring area between the covered stent 100 and the blood vessel wall after the covered stent 100 is implanted into the blood vessel, thereby increasing the anchoring stability.

[0072] Example 6

[0073] In this embodiment, please refer to Figure 17 and Figure 18The structures of the proximal segment 1 and distal segment 3 of the covered stent 100 are largely the same as in Embodiment 5, except that the first corrugated coil 12 of the distal segment 3 includes a proximal corrugated coil 121 located at the proximal end. One end of the connector 5 is connected to the distal opening 22, and the other end is connected to the proximal corrugated coil 121. Here, by connecting the connector 5 to the proximal corrugated coil 121, the proximal corrugated coil 121 is located at the proximal end of the connector 5 and is close to the connector 5. When the distal segment 3 is subjected to axial force and tends to move towards the distal end, the proximal corrugated coil 121 located at the proximal end of the connector 5 abuts against the connector 5, thereby preventing the connector 5 from pulling the covered film and thus enlarging the pores at the connection position. To further prevent the second coating 31 of the distal segment 3 from being pulled by axial force in the distal direction, the proximal end of the proximal wave ring 121 includes multiple wave crests, which are exposed on the outer surface coating 312. The connector 5 is connected to the wave crests. Here, when the outer surface coating 312 is fused with the inner surface coating 311 to form the second coating 31, the wave crests of the proximal wave ring 121 are exposed from the position of the outer surface coating 312. Thus, the connector 5 is directly connected to the exposed wave crests. After connection, when the distal segment 3 is subjected to axial force and tends to move distally, the pull position of the connector 5 on the distal segment 3 is the wave crest of the proximal wave ring 121, and it does not directly pull the coating, thereby avoiding the connector 5 pulling the coating and causing blood leakage.

[0074] In one embodiment, see Figure 19 and Figure 20Considering that the stimulation to the blood vessel wall is greater when the metal wave coil is exposed inside the blood vessel and adheres to the vessel wall than when it is covered by a membrane, a connecting sleeve 1201 can be fitted onto the wave crest 1211 of the proximal wave coil 121. The connecting sleeve 1201 has a connecting hole 12111. The connector 5 passes through the connecting hole 12111 and connects to the connecting sleeve 1201. Here, the connecting hole 12111 is located at the top of the wave crest 1211, and the size of the connecting hole 12111 is only slightly larger than the wire diameter of the connector 5. The connecting sleeve 1201 and the proximal wave coil 121 are both covered inside the outer surface membrane 312. The outer surface membrane 312 only has a membrane hole at the position of the connecting hole 12111. The connector 5 passes through the connecting hole 12111 and connects to the connecting sleeve 1201, thereby establishing a connection with the proximal wave coil 121. Compared to a wave crest that is completely covered with film, where the connector 5 is hooked onto the wave crest through the outer film 312 after film coating, the connector 5 will also tear the film during long-term oscillation, thus widening the connection gap of the connector 5. However, by providing a connecting sleeve 1201 and connecting it to the connecting hole 12111 on the connecting sleeve 1201, the size of the connecting hole 12111 directly limits the range of oscillation of the connector 5, thereby preventing the connector 5 from tearing the film. Furthermore, two connecting holes 12111 can be opened adjacent to each other on the top of the connecting sleeve 1201, allowing the connector 5 to pass through one connecting hole 12111 and exit through the other connecting hole 12111, thus forming a connection to the connecting sleeve 1201. In one embodiment, the connecting sleeve 1201 can be a metal connecting sleeve 1201 or a polymer connecting sleeve 1201.

[0075] In one embodiment, please refer to Figures 21-23In order to establish a stable connection between the distal segment 3 and the intermediate segment 2 while avoiding the generation of gaps in the connection hole 12111, the connector 5 can include a first mating part 51 and a second mating part 52. The first mating part 51 is connected to the distal opening 22, and the second mating part 52 is connected to the proximal end of the outer surface coating 312. After connection, the first mating part 51 and the second mating part 52 are adapted to each other. Here, the first mating part 51 and the second mating part 52 can be mutually adapted plug-in parts, physical adhesive parts or fasteners. In this application, the first mating part 51 and the second mating part 52 are set in the form of fasteners. The first mating part 51 has a fastening hole 511, and the second mating part 52 has a fastening block 521 protruding on its surface. The first mating part 51 can be fixed to the distal opening 22 of the intermediate segment 2 by stitching. The second mating part 52 can be fixed to the proximal position of the distal segment 3 by embedding between the outer surface covering 312 and the inner surface covering 311. During connection, the distal segment 3 is fixedly connected to the intermediate segment 2 by fitting and fastening the fastening hole 511 with the fastening block 521. Compared with liquid adhesive bonding, this connection method will not fall off due to aging over time, and it will not produce suture holes like silk thread stitching. At the same time, the fastening structure is sufficient to resist the pressure of blood vessels in the body to achieve a stable connection.

[0076] Furthermore, to avoid the protruding first mating member 51 and second mating member 52 irritating the blood vessel wall, the first mating member 51 is located on the inner surface of the distal opening 22, and the second mating member 52 is located on the proximal outer surface of the distal segment 3 opposite to the first mating member 51. Thus, after the first mating member 51 and the second mating member 52 are adapted and connected, they are hidden in the inner cavity of the middle segment 2, avoiding direct contact with the blood vessel.

[0077] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A covered stent, characterized by, The device includes a main support with a tubular body, the main support comprising, along the axial direction, a proximal segment, a middle segment, and a distal segment, wherein the diameter of the distal segment is smaller than the diameter of either the proximal segment or the middle segment; the distal end of the middle segment includes a distal opening, the distal segment being connected to the middle segment via the distal opening and only partially covering the distal opening; the surfaces of the proximal segment and the middle segment are covered with a first coating, and the surface of the distal segment is covered with a second coating, wherein the surface friction coefficient of the second coating is less than or equal to the surface friction coefficient of the first coating.

2. The stent graft of claim 1, wherein, Both the proximal segment and the distal segment include a plurality of first wave coils spaced apart along the axial direction, and the inner cavity of the middle segment is connected to an embedded support, the surface of which is provided with a second coating.

3. The stent graft of claim 2, wherein, The embedded support includes a first embedded support and a second embedded support, wherein the first embedded support is radially offset from the distal segment, and the second embedded support is connected to the distal segment.

4. The stent graft of claim 3, wherein, The intermediate section includes a plurality of second waverings spaced apart along the axial direction. The second waverings are continuous annular waverings or have openings at least at the position where they overlap with the first embedded bracket in the circumferential direction.

5. The stent graft of claim 3 or 4, wherein, The diameter of the second embedded bracket is equal to the diameter of the distal segment, and the second embedded bracket and the distal segment are integrally formed or formed separately and then connected together.

6. The stent graft of claim 5, wherein, The second coating includes an outer surface coating and an inner surface coating, which are fused together by hot pressing. The second embedded support includes a support frame, and the support frame and the first wave ring of the distal segment are both disposed between the outer surface coating and the inner surface coating.

7. The stent graft of claim 6, wherein, The outer surface coating only partially covers the outer walls of the first and second embedded brackets, or the inner surface coating only partially covers the inner wall of the first embedded bracket.

8. The stent graft of claim 6, wherein, Both the outer surface coating and the inner surface coating are formed by melting and molding multiple sub-films, and the number of sub-films in the inner surface coating is greater than or equal to the number of sub-films in the outer surface coating.

9. The stent graft of claim 8, wherein, The total number of sub-membranes in the distal segment is greater than or equal to the total number of sub-membranes in the second embedded stent and / or the first embedded stent.

10. The stent graft of claim 3, wherein, The distal opening of the middle section is flush with the distal ports of the first embedded bracket and the second embedded bracket, and the distal ports of the first embedded bracket and the second embedded bracket are mutually opposite oblique openings.

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