Covered stent

Abstract

This invention provides a covered stent, comprising a main stent having a tubular body. The main stent includes a proximal segment, a middle segment, and a distal segment along the axial direction. The middle segment includes a concave portion disposed axially on the sidewall of the middle segment. The concave portion is at least partially recessed toward the inner cavity of the middle segment, so that the middle segment forms a first channel and a second channel radially separated by the concave portion. The second channel communicates with the distal segment, and the distal side of the first channel has a distal opening. The first channel and the second channel separated by the concave portion can better facilitate blood diversion and ensure patency. At the same time, it can enhance the stability of the small stent when implanted in the first channel. Furthermore, the middle segment with the concave portion replaces the method of independently setting embedded stents and branch stents, which can minimize the radial volume of the covered stent during compression delivery.

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. These two branch channels are generally designed as either bifurcated or parallel. Bifurcation designs are larger and require a higher level of vascular anatomy expertise from the patient. Existing parallel designs typically include an embedded covered branch stent, which, when compressed, becomes too large, hindering device assembly and fabrication. Summary of the Invention

[0003] Therefore, it is necessary to provide a new covered stent that can at least stably anchor the implanted internal iliac covered stent while effectively reducing the radial volume of the covered stent after compression.

[0004] A covered stent includes a main stent having a tubular body. The main stent includes a proximal segment, a middle segment, and a distal segment in sequence along the axial direction. The middle segment includes a concave portion disposed axially on the sidewall of the middle segment. The concave portion is at least partially recessed toward the inner cavity of the middle segment, so that the middle segment forms a first channel and a second channel that are radially separated. The distal segment communicates with the second channel, and the distal side of the first channel has a distal opening.

[0005] In one embodiment, multiple recesses are provided, and the multiple recesses are symmetrically arranged on both sides of the sidewall of the middle section, so that the first channel and the second channel respectively form a near-circular radial cross section with partial overlap, and the diameter of the near-circular radial cross section of the second channel is greater than or equal to the diameter of the near-circular radial cross section of the first channel.

[0006] In one embodiment, the inner cavity of the intermediate segment includes a partition that connects to the recesses on both sides of the sidewall of the intermediate segment to isolate the first channel and the second channel.

[0007] In one embodiment, the partition at least encloses the first channel to form a circular pipe with a complete circular radial cross-section.

[0008] In one embodiment, the recessed portion is either continuously or spaced along the axial direction of the intermediate segment.

[0009] In one embodiment, the intermediate segment includes a proximal portion and a distal portion along the axial direction, wherein the depth of the recess in the proximal portion is greater than or equal to the depth of the recess in the distal portion.

[0010] In one embodiment, the intermediate section includes a surface coating and a support frame arranged along the axial direction, wherein the radial support force of the support frame in the second channel is greater than or equal to the radial support force of the support frame in the first channel.

[0011] In one embodiment, the support frame has a break in the portion of the first channel away from the second channel, and the arc length of the break is less than half the perimeter of the radial cross-section of the first channel.

[0012] In one embodiment, the support frame includes multiple support corrugations along the axial direction, and the support corrugations include multiple crests and troughs along the circumferential direction, with the concave portion located at the crest or trough position.

[0013] In one embodiment, the supporting wave coil includes a first wave coil portion surrounding the first channel and a second wave coil portion surrounding the second channel, and the surface coating includes a first coating portion surrounding the first channel and a second coating portion surrounding the second channel. The maximum expansion diameter of the first coating portion is less than or equal to the expansion diameter of the first wave coil portion in its natural state, and the maximum expansion diameter of the second coating portion is greater than or equal to the expansion diameter of the second wave coil portion in its natural state.

[0014] In one embodiment, the first wave coil portion and the second wave coil portion are integrally formed continuously, or the first wave coil portion and the second wave coil portion are disconnected at the recessed position and then movably connected.

[0015] In one embodiment, the recess includes an elastic element having an elastic support force at least in the radial direction, and the elastic element is connected to the first wave coil portion and the second wave coil portion.

[0016] The beneficial effects of this application are as follows: It provides a covered stent, including a main stent with a tubular body. The main stent includes a proximal segment, a middle segment, and a distal segment in sequence along the axial direction. The middle segment includes a concave portion, which is disposed axially on the side wall of the middle segment. The concave portion is at least partially recessed towards the inner cavity of the middle segment, so that the middle segment forms a first channel and a second channel that are radially separated by the concave portion. The second channel communicates with the distal segment, and the distal side of the first channel is provided with a distal opening. The first channel and the second channel separated by the concave portion can better shunt blood and ensure patency. At the same time, it can enhance the stability of the small stent when implanted in the first channel. Furthermore, the middle segment with the concave portion replaces the method of independently setting the embedded stent and the branch stent, which can minimize the radial volume of the covered stent during compression delivery. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the film-coated stent in Embodiment 1 of the present invention;

[0018] Figure 2 This is a schematic diagram of the internal structure of the middle section of the film-coated stent in Embodiment 1 of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of the film-coated stent connecting the small stent in Embodiment 1 of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of the first channel and the second channel with different diameters in the middle section of Embodiment 1 of the present invention;

[0021] Figure 5 This is a schematic diagram of a fracture structure in the middle section of one embodiment of the present invention;

[0022] Figure 6 This is a radial cross-sectional view of the support frame with a fracture structure in the middle section in one embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of a structure in another embodiment of the present invention, showing a partition between the first channel and the second channel;

[0024] Figure 8 This is a schematic diagram of a partition frame structure in another embodiment of the present invention;

[0025] Figure 9 This is a three-dimensional schematic diagram of a support frame structure provided at intervals in the concave portion of the middle section in one embodiment of the second embodiment of the present invention;

[0026] Figure 10 A bottom view of the recessed support frame structure in the middle section of one embodiment of the present invention;

[0027] Figure 11 This is a schematic diagram of an inner concave structure with different concave depths in the proximal and distal portions of the middle section in another embodiment of the second embodiment of the present invention.

[0028] Figure 12 This is a top view schematic diagram of the concave portion with different depths at the proximal and distal ends of the middle section in another embodiment of the second embodiment of the present invention.

[0029] Figure 13 This is a partial structural diagram of the middle section of the concave portion of the supporting wave loop located at the wave crest position in Embodiment 3 of the present invention;

[0030] Figure 14 This is a schematic diagram of the supporting wave coil structure, including a first wave coil section and a second wave coil section, in Embodiment 3 of the present invention.

[0031] Figure 15 This is a schematic diagram of the surface coating structure in Embodiment 3 of the present invention, which includes a first coating portion and a second coating portion;

[0032] Figure 16 This is a schematic diagram of the movable hook structure of the first wave coil and the second wave coil in one embodiment of the present invention;

[0033] Figure 17 This is a schematic diagram of the connection structure between the first wave coil and the second wave coil via an elastic element in another embodiment of the present invention. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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".

[0038] Example 1:

[0039] Please see Figures 1-3This application provides a covered stent 100, including a main stent 10 with a tubular body. The main stent 10 includes a proximal segment 1, a middle segment 2, and a distal segment 3 along the axial direction. Here, the covered stent 100 provided in this application is used to treat vascular lesions at bifurcation vessels. The bifurcation vessels consist of a main vessel and two branch vessels. After implantation, the proximal segment 1 is usually anchored within the covered stent 100, the middle segment 2 is located at the junction of the main vessel and the two branch vessels, and the distal segment 3 is anchored within one of the branch vessels. Typically, to facilitate the intervention and delivery of the covered stent 100, another small stent 4 needs to be additionally inserted into the covered stent 100 to complete the treatment and repair. Therefore, the middle segment 2 provided in this application is intended to provide better anchoring performance when the small stent 4 is implanted, while not affecting the intraluminal space of the other middle segments 2, thus ensuring the safety of the middle segment 2. The other cavities of segment 2 have good blood flow. Specifically, the intermediate segment 2 includes a concave portion 21, which is axially disposed on the side wall of the intermediate segment 2. The concave portion 21 is at least partially recessed towards the inner cavity of the intermediate segment 2, so that the intermediate segment 2 forms a first channel 22 and a second channel 23 that are radially separated. The distal segment 3 communicates with the second channel 23. The distal end of the first channel 22 is provided with a distal opening 221. The communication between the distal segment 3 and the second channel 23 directly receives the blood flow from the proximal segment 1 to the second channel 23, so as to further guide this part of the blood flow into the branch vessel implanted by the distal segment 3. The distal opening 221 at the distal end of the first channel 22 is used to allow the small stent 4 to extend from the distal opening 221 and extend into another branch vessel. The part of the small stent 4 located in the intermediate segment 2 is anchored and connected to the side wall where the first channel 22 is located, so as to cooperate with the covered stent 100 to reconstruct the bifurcation vessel part. Here, the recessed portion 21 allows the intermediate segment 2 to partially or completely enclose the first channel 22 and the second channel 23 radially. The distinction between the two channels allows blood flowing from the proximal segment 1 to form a clearer blood diversion in the intermediate segment 2. At the same time, the concavity of the recessed portion 21 increases the contact area between the side wall of the intermediate segment 2 and the small stent 4 when the first channel 22 is used for implantation, thereby providing more anchoring positions to increase the anchoring force and preventing the small stent 4 from falling off due to blood flushing during long-term use.

[0040] In this embodiment, please refer to Figure 2By setting the concave portion 21, the intermediate section 2 can be formed into a structure with two radially distributed channel profiles, which is beneficial for blood diversion. The lumens of the first channel 22 and the second channel 23 are interconnected. Compared with directly setting an embedded stent or setting two stents side by side, the intermediate section 2 can have a smaller radial compression volume when it is compressed and folded and sent into the outer sheath of the delivery device, so as to fit a smaller outer sheath body and provide better flexibility to pass through more tortuous vascular channels.

[0041] In this embodiment, please refer to Figure 4 To give the first channel 22 and the second channel 23 a radial cross-section that more closely resembles the structure of human blood vessels, the concave portion 21 has a V-shaped structure, with the V-shaped tip pointing towards the inner cavity of the middle section 2. Multiple concave portions 21 are provided, symmetrically arranged on both sides of the sidewall of the middle section 2, so that the first channel 22 and the second channel 23 each form a nearly circular radial cross-section with partial overlap, i.e., a figure-eight-shaped radial cross-section. Typically, the diameter of the nearly circular radial cross-section of the second channel 23 is equal to the diameter of the nearly circular radial cross-section of the first channel 22, to accommodate bifurcation vessels with the same lumen size. Furthermore, in certain types of blood vessels in the body, such as the iliac artery, the diameter of the bifurcated external iliac artery is usually larger than that of the internal iliac artery. Therefore, the stent diameter of the distal segment 3 will be set to be larger than that of the small stent 4. Thus, setting the diameter R1 of the near-circular radial section of the second channel 23 to be larger than the diameter r1 of the near-circular radial section of the first channel 22 can give the second channel 23 a larger lumen and better blood flow, thereby allowing more blood to flow to the distal segment 3. At the same time, the diameter of the second channel 23 can be matched with the diameter of the distal segment 3 to form a smoother connection. Here, the outer contours of the first channel 22 and the second channel 23 formed by the enclosed middle section 2 are formed by the overlapping of two circles on their adjacent sides. The near-circular radial section mentioned in this application refers to the fact that, on at least one cross section of the middle section 2, the outer contours of the first channel 22 or the second channel 23 have an approximately circular outline but are not complete circles, and are therefore called near-circular radial sections. The two near-circular outlines overlap to form the outer contour of the middle section 2.

[0042] In this embodiment, please refer to Figure 3 and Figure 4The intermediate segment 2 includes a surface covering 26 and a support frame 25 arranged axially. The surface covering 26 provides blood barrier capability, and the support frame 25 supports the surface covering 26 and provides support to form the intermediate segment 2 with a figure-eight radial cross-section. The proximal segment 1 and distal segment 3 may also be provided with the surface covering 26 and the support frame 25. The support frame 25 can be a mesh stent, a wave-shaped stent, or a combination of both. Furthermore, to better maintain the blood patency of the vessel anchored by the distal segment 3 connected to the second channel 23 in the long-term use of the covered stent 100 after implantation, the radial support force of the support frame 25 in the second channel 23 is greater than or equal to the radial support force of the support frame 25 in the first channel 22, thereby providing better lumen retention performance at the second channel 23 location. Specifically, the wire diameter of the support frame 25 in the second channel 23 section can be greater than that in the first channel 22 section, or the metal density of the support frame 25 in the second channel 23 section can be greater than that in the first channel 22 section at the same wire diameter.

[0043] In this embodiment, the magnitude of the radial support force of the first channel 22 and the second channel 23 in the middle section can be characterized by observing the degree of deformation of the two parts when the same force is applied to the first channel 22 and the second channel 23 respectively. The part with a greater degree of deformation has a smaller radial support force, and the part with a smaller degree of deformation has a larger radial support force. In an experiment of this embodiment, when other conditions are the same, by applying the same force to the first channel 22 and the second channel 23 in the middle section of the covered support 100 provided in this application using a flat plate force gauge, it can be observed that the deformation and deformation rate of the first channel 22 are both greater than those of the second channel 23.

[0044] In one embodiment, see Figure 5 and Figure 6To achieve a smaller radial compression volume when the intermediate segment 2 is compressed and folded before being inserted into the outer sheath of the delivery device, thus accommodating a smaller outer sheath, the compressed volume can be reduced by decreasing the density of the support skeleton 25. Specifically, the support skeleton 25 can be provided with a break 251 in the portion of the first channel 22 away from the second channel 23. This break reduces the coverage of part of the support skeleton 25, thereby reducing the compressed radial volume. Simultaneously, the figure-eight radial cross-section design of the intermediate segment 2 adds an anchoring area for the small support 4 on the other side of the break 251, ensuring that the break 251 does not affect the implantation of the small support 4. Furthermore, the arc length of the break 251 is less than half the circumference of the circle containing the radial cross-section of the first channel 22 on the cross-section of the break 251. This ensures that while the break 251 is provided, the support skeleton 25 maintains its surrounding structure in the portion of the first channel 22 away from the second channel 23, thus ensuring its anchoring stability.

[0045] In other embodiments, please refer to Figure 7 To achieve a smaller radially compressible volume in the intermediate section 2 while better isolating the first channel 22 and the second channel 23, a partition 24 can be provided within the inner cavity of the intermediate section 2. The partition 24 connects to the recesses 21 on both sides of the sidewall of the intermediate section 2 to isolate the first channel 22 and the second channel 23. This allows blood to be diverted as it enters the intermediate section 2 from the proximal section 1, preventing the blood flow from interfering with each other and creating turbulence, thus ensuring smooth blood flow. Furthermore, the partition 24 can be an insulating membrane 241 extending from the surface membrane 26 of the intermediate section 2 into the inner cavity, connecting to the surface membrane 26 at the recesses 21 to provide the effect of isolating the first channel 22 and the second channel 23.

[0046] In another embodiment, please refer to Figure 7 and Figure 8 To improve the anchoring effect of the first channel 22 of the intermediate segment 2 during the implantation of the stent 4, a septal frame 242 supporting the insulating membrane 241 can be provided simultaneously with the insulating membrane 241 in the septum 24. The septal frame 242 can help the insulating membrane 241 isolate blood while providing support to prevent it from swaying due to blood flow and thus compromising the stability of the stent. Furthermore, the septal frame 242 can protrude and bend towards the second channel 23, forming a circular tube with a curved radial cross-section with the first channel 22. This allows for a complete circumferential anchoring structure for the stent 4 during implantation, providing a better anchoring effect.

[0047] Example 2:

[0048] In this embodiment, the structure of the proximal section 1, the middle section 2 and the distal section 3 of the main support 10 is generally the same as that in Embodiment 1. The difference is that multiple recesses 21 are provided, and multiple recesses 21 can be continuously arranged along the axial direction of the middle section 2, thereby forming an axially continuous groove on the side wall of the middle section 2, so that the first channel 22 and the second channel 23 form a channel with a uniform axial diameter.

[0049] In one embodiment, see Figure 9 and Figure 10 The concave portions 21 can be spaced apart along the axial direction. Here, the intermediate section 2 may include a first section 201 with a figure-eight-shaped radial cross section having the concave portions 21, and an elliptical or sausage-shaped second section 202 without the concave portions 21. The first section 201 and the second section 202 are staggered. In this way, the first section 201 can provide better anchoring performance for the small stent 4, while the second section 202 can provide a larger lumen volume for the distal section 3 connected to the second channel 23. While ensuring blood flow, the second section 202 can provide a better area for anchoring with the vascular sidewall, thereby enhancing the vascular anchoring force of the covered stent 100 in the intermediate section 2.

[0050] In another embodiment, please refer to Figures 11-12To ensure that the small stent 4, at least at its proximal end, establishes a good anchoring effect with the intermediate segment 2 when implanted, and that the distal end of the intermediate segment 2 has a better swing effect while maintaining stable anchoring, specifically, the intermediate segment 2 includes a proximal portion 203 and a distal portion 204 along the axial direction. The depth H1 of the concave portion 21 of the proximal portion 203 is greater than or equal to the depth H2 of the concave portion 21 of the distal portion 204. Here, when the depth of the concave portion 21 of the proximal portion 203 is equal to the depth of the concave portion 21 of the distal portion 204, and the diameter of the near-circular radial section of the first channel 22 is less than or equal to the diameter of the small stent 4, the first channel 22 can provide a better anchoring force to the small stent 4 along the entire axial direction, thereby enabling the small stent 4 to be stably anchored within the first channel 22. When the depth H1 of the concave portion 21 of the proximal portion 203 is greater than the depth H2 of the concave portion 21 of the distal portion 204, the depth H1 of the concave portion 203 should be set such that the diameter of the first channel 22 is less than or equal to the diameter of the stent 4. The depth H1 of the concave portion 204 can then be reduced to 0, meaning the concave portion does not exist. Since the proximal port of the stent 4 is a crucial location for blood flow after implantation into the intermediate segment 2, the stability of its anchoring position is paramount. Increasing the depth of the concave portion 203 in the proximal portion of the intermediate segment 2 makes the diameter of the first channel 22 less than or equal to the diameter of the stent 4. The proximal portion 203 of channel 22 provides more anchoring positions and stronger compressive force, which can stably anchor the stent 4, including the proximal port portion 203, within the intermediate segment 2, thereby preventing the stent 4 from dislodging under blood flushing and from swinging randomly within the intermediate segment 2. The reduced depth of the distal segment 3 reduces the anchoring area between the stent 4 and the sidewall of the intermediate segment 2, thus providing the stent 4 with some swing space at the distal opening 221 of the first channel 22, thereby increasing the swing amplitude of the stent 4 at that location and allowing it to better adapt to more tortuous blood vessel types. Furthermore, the depth of the concave portion 21 can be set to gradually decrease from the proximal portion 203 to the distal portion 204.

[0051] In this embodiment, the support frame 25 can be a support wavering 250 spaced apart along the axial direction, the concave portion 21 is provided on both sides of the wavering support symmetrically in the circumferential direction, and the concave portion 21 with different concave depth can be multiple wavering supports spaced apart along the axial direction with different concave depths, the first section 201 is an 8-shaped wavering support with a figure-eight-shaped radial cross section, and the second section 202 is a wavering support with an elliptical or sausage-shaped structure.

[0052] Example 3:

[0053] In this embodiment, please refer to Figure 13The structure of the proximal section 1, middle section 2, and distal section 3 of the main support 10 is largely the same as that in Embodiments 1 and 2. The difference lies in that the support frame 25 includes multiple support corrugations 250 along the axial direction, and the support corrugations 250 include multiple crests 2501 and troughs 2502 along the circumferential direction. The concave portion 21 is located at the crest 2501 or trough 2502. The support corrugations 250 can be made of stainless steel wire or nickel-titanium wire. The support corrugations 250 themselves have radial expansion capability, which can provide good elastic support force, and make the support corrugations... The rings 250 are spaced apart in the middle section 2, which gives the middle section 2 a certain degree of flexibility. The concave part 21 is set at the crest 2501 or trough 2502. When the support ring 250 is formed, the crest 2501 and trough 2502 are the positions that need to be bent. While processing their bending, it is further processed into a concave structure, which can reduce the number of process steps. Furthermore, it can avoid the concave part 21 being formed on the wave rod used to connect the crest 2501 and trough 2502, thereby avoiding damage to the integrity of the wave rod and affecting its axial support performance.

[0054] In this embodiment, please refer to Figure 14 and Figure 15In order to provide better anchoring force for the stent 4 in the first channel 22 and better blood flow in the second channel 23, it should be understood that blood flow in the human body has blood pressure, and blood vessels are elastic, undergoing partial expansion and contraction with changes in blood pressure. Therefore, in the first channel 22 section where better anchoring force is desired, the first channel 22 can resist vascular dilation without radial size increase, thus ensuring long-term stability of the stent 4 anchorage. In the second channel 23 section where better blood flow is desired, the second channel... 23 can expand or contract in response to changes in blood pressure and blood vessels, thus providing better blood flow. Specifically, the supporting coil 250 includes a first coil portion 2503 surrounding the first channel 22 and a second coil portion 2504 surrounding the second channel 23. The surface coating 26 includes a first coating portion 261 surrounding the first channel 22 and a second coating portion 262 surrounding the second channel 23. The maximum expansion diameter r3 of the first coating portion 261 is less than or equal to the natural expansion diameter r2 of the first coil portion 2503. The maximum expansion diameter R3 of the second coating portion 262 is greater than or equal to... The expansion diameter R2 of the second wave coil portion 2504 in its natural state; here, the first wave coil portion 2503 and the second wave coil portion 2504 respectively provide radial support force for the first channel 22 and the second channel 23. At the same time, since the wave coil structure itself is elastic and can be compressed or expanded, the coating applied to the surface of the wave coil structure has low elasticity. Under the condition of reasonably setting the maximum expansion diameter, it can play the role of limiting the further expansion of the wave coil structure. The maximum expansion diameter r3 of the first coating portion 261 applied to the first wave coil portion 2503 and the second coating portion 261 applied to the second wave coil portion 2504 are related to the expansion diameter R2 of the second coating portion 261 applied to the second wave coil portion 2504. The maximum expansion diameter R3 of the membrane portion 262 is set to different sizes, so that the maximum expansion diameter r3 of the first covering portion 261 is less than or equal to the expansion diameter r2 of the first wave coil portion 2503 in its natural state. In this way, when the intermediate segment 2 is implanted into the blood vessel and expands, after the first wave coil portion 2503 expands to the size of the lumen in its natural state, the first covering portion 261 expands to its maximum diameter. Thus, even if the first wave coil portion 2503 has a tendency to expand outward under the impact of blood flow, it is restricted by the first covering portion 261 and cannot expand, thereby ensuring the stability of the first channel 22 anchoring the small stent 4. The maximum expansion diameter R3 of the second membrane portion 262 is greater than or equal to the expansion diameter R2 of the second wave portion 2504 in its natural state. This means that after the second wave portion 2504 expands to its natural lumen, the second membrane portion 262 is not fully expanded. This allows the second wave portion 2504 to better adapt to the shape of the blood vessel as the blood flows and expands and contracts with the pulsation of the blood vessel, thus enabling the blood to pass through more smoothly.Through the above structural design, even though the support wave coil 250 is integrally formed, after the formation of the first channel 22 and the second channel 23, the first channel 22 and the second channel 23 exhibit two completely different characteristics due to the different restrictions imposed on the two channels by the coating.

[0055] In this embodiment, after the intermediate segment 2 with different maximum expansion diameters of the coating is formed, in the natural state of the coating support 100, on the outer surface of the intermediate segment 2, the first coating portion 261 on the first channel 22 has a relatively flat coating surface, while the second coating portion 262 on the second channel 23 forms an uneven surface with more wrinkles. Here, since the maximum expansion diameter of the first coating portion 261 is greater than the expansion diameter of the first corrugated portion 2503 in its natural state, the first corrugated portion 2530 of the first channel 22 is in a compressed and taut state. Therefore, in the natural state of the coating support 100, when the first channel 22 is expanded from the inner cavity of the first channel 22, no significant radial expansion of the channel size occurs. However, when the second channel 23 is expanded from the inner cavity of the second channel 23, a more significant radial expansion of the channel size can be observed.

[0056] In one embodiment, see Figure 16 To avoid the first channel 22 and the second channel 23 with different expansion characteristics from affecting each other, specifically, the supporting wave coil 250 can be directly disconnected at the concave portion 21, thereby forming a first wave coil portion 2503 and a second wave coil portion 2504 that are separated from each other. The disconnection position is connected only by the surface coating 26. Alternatively, the first wave coil portion 2503 and the second wave coil portion 2504 can be disconnected at the concave portion 21 and then movably connected. Specifically, the connection position of the first wave coil portion 2503 and the second wave coil portion 2504 can be set as a ring structure 5 and hooked to each other, thereby forming a movable hook structure. In this way, when the second wave coil portion 2504 expands, the expansion force will not directly affect the shape of the first wave coil portion 2503.

[0057] In another embodiment, please refer to Figure 17 To ensure the integrity and radial support force of the support coil 250 through integral continuous molding, while reducing the mutual influence between the first coil portion 2503 and the second coil portion 2504, the recessed portion 21 can include an elastic member 6. The elastic member 6 has elastic support force at least in the radial direction. The elastic member 6 is connected to the first coil portion 2503 and the second coil portion 2504. The elastic member allows the radial elastic support force of the elastic member 6 to buffer most of the expansion force when the second coil expands radially and is transmitted to the first coil portion 2503 through the recessed portion 21, thereby significantly reducing the transmitted expansion force and ensuring the stability of the second coil. Specifically, the elastic member 6 can have a W-shaped bending structure.

[0058] 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 in that, The device includes a main support with a tubular body, the main support comprising a proximal section, a middle section and a distal section in sequence along the axial direction, the middle section including a concave portion disposed axially on the side wall of the middle section, the concave portion being at least partially recessed toward the inner cavity of the middle section, such that the middle section forms a first channel and a second channel radially separated by the concave portion, the second channel communicating with the distal section, and the distal side of the first channel having a distal opening.

2. The covered stent according to claim 1, characterized in that, The recessed portion is provided in multiple ways, and the multiple recessed portions are symmetrically arranged on both sides of the side wall of the middle section, such that on at least one cross section of the middle section, the first channel and the second channel respectively form a near-circular radial section, the two near-circular radial sections partially overlap, and the diameter of the near-circular radial section of the second channel is greater than or equal to the diameter of the near-circular radial section of the first channel.

3. The covered stent according to claim 4, characterized in that, The inner cavity of the intermediate section includes a partition, which is connected to the recesses located on both sides of the sidewall of the intermediate section to isolate the first channel and the second channel.

4. The coated stent according to claim 5, characterized in that, The partition at least encloses the first channel to form a circular pipe with a complete circular radial cross-section.

5. The covered stent according to claim 1, characterized in that, The concave portion is either continuously or intermittently arranged along the axial direction of the middle section.

6. The covered stent according to claim 5, characterized in that, The intermediate segment includes a proximal portion and a distal portion along the axial direction, wherein the depth of the recess in the proximal portion is greater than or equal to the depth of the recess in the distal portion.

7. The covered stent according to any one of claims 1-5, characterized in that, The intermediate section includes a surface coating and a support frame arranged along the axial direction, wherein the radial support force of the support frame in the second channel is greater than or equal to the radial support force of the support frame in the first channel.

8. The covered stent according to claim 7, characterized in that, The supporting frame has a break in the portion of the first channel away from the second channel; the arc length of the break is less than half the circumference of the first channel on the cross-section of the break.

9. The covered stent according to claim 7, characterized in that, The support frame includes multiple support corrugations along the axial direction, and the support corrugations include multiple crests and troughs along the circumferential direction. The concave portion is located at the crest or trough position.

10. The covered stent according to claim 9, characterized in that, The supporting wave coil includes a first wave coil portion surrounding the first channel and a second wave coil portion surrounding the second channel. The surface coating includes a first coating portion surrounding the first channel and a second coating portion surrounding the second channel. The maximum expansion diameter of the first coating portion is less than or equal to the expansion diameter of the first wave coil portion in its natural state, and the maximum expansion diameter of the second coating portion is greater than or equal to the expansion diameter of the second wave coil portion in its natural state.

11. The covered stent according to claim 10, characterized in that, The first wave coil portion and the second wave coil portion are integrally formed continuously, or the first wave coil portion and the second wave coil portion are disconnected at the concave position and then movably connected.

12. The covered stent according to claim 11, characterized in that, The recessed portion includes an elastic element, which has an elastic support force at least in the radial direction, and the elastic element is connected to the first wave coil portion and the second wave coil portion.

Images