Full-Length Aortic Stent, Stent Kit, and Stent Delivery System - Patent application

Abstract

The present invention relates to a stent for the entire length of the aorta, a stent kit, and a stent delivery system, the stent comprising a stent body and a cavity surrounded by the stent body, the stent having a length of 200 to 600 mm and an outer diameter that gradually narrows from 60 to 30 mm to 30 to 10 mm, the stent body being braided with wires of at least two different diameters, and having a structure that allows compression and expansion along the axial direction of the stent at any position in a released state, the first wire having a diameter of 20 to 150 μm, the second wire having a diameter of 150 to 800 μm, and at least one branched stent fixing mechanism provided within the cavity.

Description

[Technical field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application is filed based on a Chinese patent application bearing application number 202220454074.2, filed with the China Patent Office on March 3, 2022, and claims priority to said Chinese patent application, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a stent, a stent kit, and a stent delivery system, in particular to a full-length aortic stent, a stent kit, and a delivery system in the treatment of aortic pathologies such as aortic aneurysm or aortic dissection. [Background technology]

[0003] The arterial wall is made up of the intima, media, and adventitia, which are tightly attached to each other. When the inner wall of the arterial blood vessel is locally damaged, the strong impact of the arterial blood flow causes the media of the arterial wall to gradually peel off, and blood enters between the media and adventitia of the vascular wall, forming two cavities: a true lumen and a false lumen. The most common is aortic dissection. Aortic dissection weakens the arterial wall and is at risk of rupture at any time. If the rupture of the tunica media occurs, the patient will die within a few minutes.

[0004] Aortic dissections are classified into two types (e.g., Stanford classification) according to the location of the intimal tear and the extent of stretching: type A and type B. Type A refers to lesions involving the ascending aorta, where the dissection of the arterial wall begins in the ascending aorta or occurs in the aortic arch or proximal end of the descending aorta, but may also involve the ascending aorta. Type B refers to dissection of the arterial wall occurring in the descending aorta but not beyond the proximal end of the opening of the left subclavian artery.

[0005] Aortic aneurysm is another type of disease in which the aorta becomes abnormally enlarged. If an aortic aneurysm ruptures, it can be fatal to the patient.

[0006] Therefore, early diagnosis and timely treatment of aortic dissection and aortic aneurysm are highly necessary.

[0007] Currently, a low-cost, low-risk interventional therapy for the treatment of aortic dissection or aortic aneurysm is stent placement.

[0008] Stent grafts are usually used to treat aortic dissection or aortic aneurysm. When the lesion site extends to the aortic arch and / or abdominal aorta site with branch arterial vessels, a common method to avoid the occlusion of the branch arteries by the stent is to drill holes in the stent graft site corresponding to the important branch arteries on-site. This method increases the difficulty of the operation and needs to be performed by experienced surgeons, while it may cause serious consequences if the important branch vessels are occluded due to inaccurate positioning during placement or stent migration during the release process. In addition, manufacturers may refuse to provide quality assurance services if the stent is modified before surgery.

[0009] Recently, a method of using a high-density mesh stent to perform intraluminal intervention of the aorta has been proposed. Unlike the EVAR intraluminal intervention method, this method does not adopt a mechanism of mechanically blocking the false lumen, and the high-density mesh stent does not significantly impede the passage of blood flow, and forms a blood flow obstruction on the inner wall of the diseased blood vessel, thereby changing the hemodynamics in the false lumen, reducing the pressure therein, and promoting intraluminal thrombosis to achieve the treatment purpose. In this method, the use of a high-density mesh stent not only has the advantages of less trauma, faster recovery, and lower mortality compared with the EVAR intraluminal intervention method, but also greatly reduces the difficulty of the operation because the high-density mesh stent does not significantly impede the blood flow to the branch arteries, so that doctors with ordinary experience can also perform it.

[0010] However, the therapeutic effect of this type of stent is not ideal, the tears in the inner wall of the blood vessel are not completely sealed, and ideal intraluminal thrombus is not always formed. Moreover, the current high-density mesh stent is still difficult to apply to all types of aortic dissection and aortic aneurysm lesions, especially to type A aortic lesions.

[0011] Type A aortic dissection involves the ascending aorta, where the internal diameter of the vessel at that site increases significantly due to the lesion, usually to 38-55 cm. Such large diameter dense mesh stents cannot be radially compressed to a smaller diameter, and therefore require a thicker delivery system. This makes it difficult, or even impossible, to place the delivery system through the femoral artery, which has a relatively small diameter, especially for Asians, whose vessels are relatively small. To reduce the diameter of the stent in the compressed state, the stent can be braided with relatively thin wires, but this results in insufficient radial support of the stent, which is unable to exert its therapeutic effect.

[0012] In addition, type A aortic dissection lesions often involve the descending aorta and abdominal aorta. In such cases, multiple stents need to be placed, which not only increases the surgical risk but also the surgical cost due to the long surgical time and the large number of stents.

[0013] Therefore, for aortic dissection lesions involving a large area of ​​the aorta, there remains a need for stents that can improve the safety of surgery and allow the surgery to be completed quickly. Summary of the Invention

[0014] In view of this, the main objective of the present invention is to provide a high-density mesh stent and its delivery system applicable to the entire length of the aortic vessel, the diameter of which is designed to pass through the femoral artery in the delivery state, and is suitable for treating aortic dissection or aortic aneurysm, especially for treating lesions involving the entire aorta. When the stent is released, it can be locally axially compressed and / or expanded by adjusting the delivery system, and the length after placement can be adapted to any patient. In addition, by adjusting the degree of local compression, it can effectively seal the tears in the inner wall of the vessel that cause aortic dissection and provide enhanced radial support to the vessel wall, thereby achieving a better treatment effect.

[0015] It is a further object of the present invention to provide a stent kit comprising the above-mentioned stent and a branch artery stent for use in combination with the above-mentioned stent, which upon release forms a stable stent combination and provides effective treatment and prevention of existing, potential or deteriorating disease sites in the aorta and major branch arterial vessels of a patient.

[0016] To this end, a first aspect of the present invention provides a stent for use in the entire aorta, the stent comprising a stent body and a cavity surrounded by the stent body, the stent having a length of 200 to 600 mm and an outer diameter gradually tapering from 60 to 30 mm to 30 to 10 mm, the stent body being braided with wires having at least two different diameters and having a structure that is compressible and extensible at any site along the axial direction of the stent in a released state, wherein a first wire has a diameter of 20 to 150 μm and a second wire has a diameter of 150 to 800 μm, and at least one branched stent fixing mechanism is provided within the cavity.

[0017] The stent is a stent for the entire aorta, and has a total length of 400-600 mm in the natural state, and can be appropriately compressed / expanded when placed in a blood vessel to obtain an appropriate length suitable for the aortic structure of different patients. Furthermore, since the inner diameter gradually narrows from the proximal end of the aorta to the abdominal aorta, the outer diameter of the stent also gradually narrows from 60-30 mm at the proximal end (ascending aorta portion) to 30-10 mm at the distal end (abdominal aorta portion), allowing it to adapt to the physiological structure of the aorta where a lesion has occurred.

[0018] The stent can be axially compressed and expanded at any site during the release process, especially according to the stent delivery system and stent placement method described below. And unlike the current high-density mesh stent used in the aorta, the stent is braided by at least two different diameter wires. On the one hand, when the stent is released in the vessel, the total length of the stent can be adjusted to fit the structure and length of the aortic vessel of different patients by local axial compression and / or expansion. On the other hand, the thick second wire plays the role of forming the basic stent frame and providing basic radial support, and the thin first wire plays the role of effectively filling the gap between the second wires and providing auxiliary support and maintaining the stent shape. When the stent is compressed in the axial direction, the presence of the first wire significantly reduces the fluid permeability of the compressed portion, effectively sealing the cleft site of the blood vessel inner wall, and at the same time, when the thick second wire is compressed in the axial direction, the density of the second wire per unit length increases, forming a significantly strengthened radial support force, thereby playing a role in expanding the true lumen of the blood vessel, which is favorable for reducing the false lumen. In this way, the two types of wire diameter ranges of the stent complement each other to exert a better therapeutic effect. On the other hand, due to the above characteristics, the stent can be easily compressed into a delivery configuration with an appropriate diameter by stretching the stent in the axial direction to significantly reduce the density of the braided wire, and then compressing it in the radial direction, and can be easily assembled into the delivery system described below. Thus, a stent for the entire aorta can be delivered using a delivery device with a normal diameter (e.g., 5 to 10 mm) even if it has a proximal end with an outer diameter of up to 50 to 60 mm after release. In addition, due to the above-mentioned characteristics of the stent, any mesh constituting the stent is easy to expand, and the branch stent can be placed through the mesh at any suitable position in the branch artery as necessary, while the tail of the branch stent is firmly fixed in the lumen of the stent by the branch stent fixing device.

[0019] According to one embodiment, in a naturally relaxed state (ie, without axial compression or stretching), the stent has a metal coverage of at least 30% and a radial support force of 100N or more.

[0020] According to one embodiment, the stent has a metal coverage of 30-90% and a radial support force of 100-600N in a naturally released state. As described above, the stent is locally compressed during the release process to form a segment with low liquid permeability and high support force, thereby sealing the cracks in the blood vessel inner wall and exerting a therapeutic effect. Thus, according to one embodiment, the stent has a metal coverage of at least 80% and a radial support force of 400N or more in a released and axially maximally compressed state. According to one specific embodiment, the stent has a metal coverage of 80-100% and a radial support force of 400-1000N in a released and axially maximally compressed state. By having a radial support force within the above range after the stent is axially maximally compressed, it is possible to effectively support the narrowed blood vessel true lumen. In particular, a radial support force within the preferred range is particularly effective for affected areas that have been formed for a certain amount of time, where the torn vascular intima fragments have hardened and a large force is required to expand them.

[0021] Therefore, in practical application, when the stent is released in a blood vessel (especially the aorta), it has different compression ratios along its axial direction. The radial support force of different parts of the stent can vary within the range of 100-1000N, and the metal coverage can vary within the range of 30-100%.

[0022] Stents require the right braid density: if the braid is too dense, radial compression may be difficult even with fewer second wires, while if the braid is too loose, axial compression may be difficult to effectively seal the intimal tear.

[0023] Therefore, in practical applications, when the stent is released in a blood vessel, the metal coverage at different sites may be different depending on the compression / stretch ratio, for example, between the metal coverage at maximum axial compression and the metal coverage at natural release or moderate stretch.

[0024] The above-mentioned characteristics of the stent allow it to flexibly meet various treatment needs of blood vessels throughout the entire length of the aorta, from the ascending aorta to the abdominal aorta, and simultaneously meet needs such as repairing tears, expanding the true lumen of the blood vessel, reducing the false lumen, and ensuring blood flow in branch arteries.

[0025] According to one embodiment, a branch stent fixing mechanism for fixing a branch stent is provided in the stent lumen at a segment corresponding to a main branch vessel close to the aortic arch and / or abdominal aorta. Specifically, the branch stent fixing mechanism comprises at least one circular hole that fits the outer diameter of the fixing part of a branch stent of a stent kit described below, and the circular hole is provided in the lumen of the stent approximately perpendicular to the inner wall of the stent body, so that the fixing part of the branch stent can be firmly joined with the branch stent fixing mechanism when inserted into the circular hole. Therefore, in this embodiment, the inner diameter of the circular hole is preferably slightly smaller than the outer diameter of the fixing end of the branch stent.

[0026] According to one embodiment, depending on the corresponding site, the branch stent fixing mechanism comprises two or three circular holes for fixing two or three branch stents. More specifically, each circular hole may be arranged tangent to each other.

[0027] According to one embodiment, the branch stent fixation mechanism may be integrally braided with the stent body of the stent, thereby fixedly connecting it to the inner wall of the stent body.

[0028] According to one embodiment, different segments of the stent can have different metal coverage and / or radial support within the above ranges. By varying the braiding of the metal wires, different metal coverage and / or radial support can be obtained, thereby adapting to the requirements of different regions of the aorta.

[0029] According to one embodiment, in the naturally released state, at least some segments of the stent have substantially complete liquid permeability, i.e., little or no obstruction to blood flow from the aorta to the branch arteries. According to the embodiment, in the naturally released state, the segments, for example, the segment corresponding to the descending aorta portion and / or the segment corresponding to the abdominal aorta portion, can have a metal coverage of 30-60% and a radial support force of 200-600N. A stent having a radial support force and a metal coverage within the specified range has a relatively low radial support force and metal coverage in the naturally released state, but has a large compression ratio, and even after compression, can form the necessary radial support force and metal coverage that meet the above specifications, and can effectively seal tears in the inner wall of the blood vessel. The stent has a metal coverage of 80-90% and a radial support force of 400-1000N in the released and maximally compressed axial state.

[0030] At the same time, in the naturally released state, at least another part of the segments of the stent has a metal coverage of 60-90%, for example 70-90%, and a radial support force of 100-600N. A stent having a radial support force and a metal coverage rate within the specified range has a relatively high radial support force and metal coverage rate even in the naturally released state, has a large elongation rate, and can be radially compressed to an appropriate size and assembled into an appropriate delivery system even after being elongated. After being locally released, the stent of this embodiment has a relatively large radial support force and metal coverage rate without compression, and can immediately support and expand the vascular true lumen and block the crack to a certain extent. Furthermore, the radial support force and metal coverage rate can be further increased by axially compressing a local segment of the stent to form the required radial support force and metal coverage rate specified above, and more effectively block the crack in the inner wall of the blood vessel. The stent, in its released and maximally axially compressed state, has a metal coverage of 90-100%, for example 90-95%, and a radial support force of 500-1000 N. Such segments are particularly suitable for the ascending aorta and / or aortic arch region.

[0031] According to this embodiment, in the naturally released state, the segments of the stent having a relatively high metal coverage have a certain (not complete) liquid permeability, i.e., they provide a certain obstruction to the blood flow from the artery to the branch artery. In one specific embodiment, the stent is axially expandable, so that when the stent is placed, the local segments corresponding to the branch vessels can be appropriately stretched to obtain a suitable blood permeability. Therefore, the corresponding portions of the stent are configured to have a larger diameter than the adjacent portions, so that the diameter after the stretching of the region fits the inner diameter of the vessel lumen having the branch vessel.

[0032] According to another embodiment, the stent further comprises a bifurcation segment corresponding to the left and right common iliac arteries, wherein the bifurcation segment includes a first longer common iliac artery segment and a second shorter common iliac artery segment, wherein the first common iliac artery segment is ultimately placed in one common iliac artery through which the stent is delivered, and the second common iliac artery segment is ultimately placed in the other common iliac artery.

[0033] If necessary, an additional stent can be further placed in the common iliac artery where the second common iliac artery segment is located to support a longer length of vessel.

[0034] According to a preferred embodiment, the first wires used in the stent may have a diameter of 50-150 μm and the second wires may have a diameter of 150-600 μm. The stent is braided with 48-202 wires, where the number of the second wires is 4-32 and the remaining are the first wires.

[0035] According to one embodiment, the stent is braided with three types of wires having different diameters, where the second wires may include a first thick wire and a second thick wire having different diameters. According to a specific embodiment, the first thick wire may have a diameter of 150 to 300 μm, and the second thick wire may have a diameter of 300 to 600 μm. The stent is braided with 48 to 202 wires, where the second wires include 6 to 24 first thick wires and 4 to 24 second thick wires, with the remainder being first wires, provided that the total number of the first thick wires and the second thick wires does not exceed 30.

[0036] According to another embodiment, the stent is braided with wires having three different diameters, where the first wires may include a first thin wire and a second thin wire having different diameters. According to a specific embodiment, the first thin wire may have a diameter of 50-100 μm and the second thin wire may have a diameter of 100-150 μm. The stent is braided with 48-202 wires, where the second wires are 4-30 and the rest are first wires, where the first wires include 32-166 of the first thin wires and 32-166 of the second thin wires, provided that the total number of the first thin wires and the second thin wires does not exceed 198.

[0037] According to yet another embodiment, the stent is braided with four different diameter wires: a first thin wire, a second thin wire, a first thick wire, and a second thick wire.

[0038] If there are too many thick wires (i.e., second wires), the stent cannot be effectively compressed to the desired delivery state, and if there are too few, the stent will not provide the expected radial support after compression and will not be able to maintain the expected structure and configuration of the stent in the released state. On the other hand, the thin wires (i.e., first wires) serve to fill the gaps of the second wires, increasing the metal coverage without excessively increasing the support, and effectively sealing the gaps in the blood vessel. However, the amount of first wires used should not be too large, as too many first wires will make it difficult to compress the stent to a delivery state with the appropriate diameter.

[0039] In an embodiment in which the stent has a metal coverage of 30-60% and a radial support force of 200-600N in a naturally released state, the number of wires for braiding the stent may be 48-156, for example, 48-128. Here, the number of second wires may be 4-30, and the remainder may be first wires. According to one specific embodiment, the stent is braided with two types of first wires and one type of second wire, in which 4-30 of the second wires are used, and the remainder are first wires, and the first wires may include 32-120 first thin wires and 32-120 second thin wires, provided that the total number of the first thin wires and the second thin wires does not exceed 152. According to another specific embodiment, the stent is braided with one type of first wire and two types of second wires, where the second wires include 6 to 24 first thick wires and 6 to 24 second thick wires, with the remainder being first wires, provided that the total number of the first thick wires and the second thick wires does not exceed 30.

[0040] In an embodiment in which the stent has a metal coverage of 60-90% and a radial support force of 100-600N in a naturally released state, the number of wires for braiding the stent may be 96-202, for example, 96-156. Here, the number of second wires may be 4-30, for example, 4-24, and the remainder is the first wire. According to one specific embodiment, when two types of thick wires of different diameters are used, the second wires include 6-12 first thick wires and 4-12 second thick wires, and the remainder is the first wire. If the number of thick wires (i.e., second wires) is too large, the stent cannot be effectively compressed to the desired delivery state, and if the number is too small, the stent cannot provide the expected radial support force even after compression and cannot maintain the expected structure and configuration of the stent in the released state. According to another specific embodiment, when two types of thin wires of different diameters are used, the second wires are 4 to 30, for example 4 to 24, and the remainder are first wires, where the first wires include 32 to 120 of the first thin wires and 32 to 120 of the second thin wires, provided that the sum of the first thin wires and the second thin wires does not exceed 198.

[0041] According to one embodiment, the stent is composed of at least two layers of braided mesh. According to one embodiment, the stent has 2 to 4 layers of braided mesh. When the stent has multiple layers of braided mesh, the entire stent has the above-specified radial support and metal coverage.

[0042] The braiding method of the stent is not particularly limited. As long as the stent can be easily compressed and expanded in the axial direction, a normal overlapping braid (i.e., no binding at the crossing portions of the wires) can be adopted.

[0043] It should be understood that, based on the radial support range and metal coverage range required for a specific treatment type, a person skilled in the art can select an appropriate braiding material under specific device conditions, determine a reasonable number of layers, and further determine the appropriate wire diameter, quantity, etc., and determine an appropriate braiding scheme based on the description in this specification, to obtain a stent with the desired radial support range and metal coverage range. For example, an appropriate braiding scheme can be designed by dedicated software.

[0044] According to a further embodiment, the ends of the stent (especially the proximal end where the radial support of the stent is the largest) can be formed in a back-knitted manner. If there is a burr that cannot be back-knitted again at the other end, the burr can be located inside the stent by selecting a suitable distribution manner for each layer. Or, if there are two layers of burrs, one layer of the burr can be back-knitted for a short distance and another burr can be wrapped in the back-knitted step, or if multiple stents are used together, a single layer or two layers of burrs can be overlapped and placed inside another mesh stent. The stent in this embodiment has smooth ends, thereby avoiding mechanical damage to the inner wall of the blood vessel caused by exposed wire ends (burrs).

[0045] According to one embodiment, the stent has a first segment located at the proximal end, a second segment, and a third segment. The first segment has a tapered diameter in the range of 55-38 mm to suit the ascending aorta, and the length of the first segment is 8-11 cm, for example 8-10 cm. The second segment is adjacent to the first segment and has a tapered diameter in the range of 38-20 mm to suit the portion of the artery from the aortic arch to the abdominal aorta, and the length of the second segment may be 28-40 cm, for example 28-31 cm. The third segment is adjacent to the second segment and has a branch, where the pre-branch portion has a diameter of 20-32 mm, the long branch (i.e., the first common iliac artery segment) has a diameter of 10-16 mm and a length of 5-20 cm to suit the common iliac artery into which the stent is delivered, and the short branch (i.e., the second common iliac artery segment) has a diameter of 10-16 mm and a length of 5-20 cm to facilitate release into another common iliac artery.

[0046] The stent can be self-expandable or balloon expandable. The materials of the first and second wires for braiding the stent can be different, but are preferably the same. Typically, the material of the wires can be a metal, such as a shape memory alloy (e.g., Nitinol), a cobalt chromium alloy, tungsten, or tantalum.

[0047] A second aspect of the invention provides a stent kit comprising a full length aortic stent as described above and a branch stent for at least one branch arterial vessel of the aorta.

[0048] According to one embodiment, the branch stent comprises a support portion and a fixation portion, wherein the support portion is configured to be positioned in and support a corresponding branch arterial vessel after the branch stent is deployed, and the fixation portion is provided within a lumen of the stent and extends through a branch stent fixation mechanism provided within the lumen, thereby fixing the branch stent relative to the full-length aortic stent.

[0049] According to one specific embodiment, the support part and the fixation part of the branch stent may have the same diameter or different diameters. More specifically, the support part may have an outer diameter that matches the inner diameter of the branch vessel. The fixation part has an outer diameter that is slightly larger than the inner diameter of the circular hole of the branch stent fixation mechanism, so that the branch stent is firmly joined to the branch stent fixation mechanism, as described above.

[0050] According to one specific embodiment, the branch stent has an opening in the side wall of the anchoring part, the opening being configured to allow unhindered blood flow in the aorta to pass through the anchoring part after the branch stent is placed in the branch arterial vessel.

[0051] According to another specific embodiment, the support and anchor parts of the branch stent are disposed at an angle, the angle being approximately equal to the included angle between the branch vessel and the aortic vessel, and the anchor part has an opening at its end proximal to the support part, the projection of the opening at least partially overlapping the end opening of the anchor part, thereby forming a through channel inside the anchor part.

[0052] According to one embodiment, the stent kit may comprise 1 to 7 of the above branched stents.

[0053] A third aspect of the invention provides a stent delivery system comprising a delivery catheter and a full-length aortic stent as described above.

[0054] The delivery catheter includes an outer catheter, an inner catheter, and a push rod arranged coaxially from outside to inside, wherein the outer catheter has a proximal end and a distal end and has a first lumen extending therethrough, the inner catheter extends into the first lumen at the distal end of the outer catheter and has a second lumen extending therethrough, and the push rod extends through the first lumen of the outer catheter and the second lumen of the inner catheter and exits the distal end of the inner catheter.

[0055] In a delivery configuration, the stent is releasably retained between the push rod and the outer catheter and is located within a first lumen in the proximal end of the outer catheter.

[0056] The delivery catheter is configured such that the outer catheter, the inner catheter, and the push rod are axially movable relative to one another, and opposite ends of the stent are releasably constrained to the proximal end of the push rod and the proximal end of the inner catheter, respectively.

[0057] According to one embodiment, in a stent delivery system, both ends of a stent (i.e., the proximal and distal ends) are releasably constrained to the proximal end of a push rod and the proximal end of an inner catheter, respectively, such that, to release the stent, the outer catheter is held stationary and the push rod is pushed toward the heart, causing the push rod to move the stent and inner catheter toward the heart while the outer catheter moves relatively away from the heart, thereby releasing the stent from its proximal end.

[0058] Since the proximal end of the stent is restrained by the proximal end of the push rod, the stent is not fully expanded at the time of initial release and is in a semi-released state. At this time, the stent has not reached the diameter of the fully released state and is not in close contact with the vascular wall, so that the position can be easily adjusted. For example, the partially released stent can be retrieved into the delivery catheter and released again after adjusting the position. There is another advantage to restraining the proximal end of the stent by the proximal end of the push rod, that is, the frictional resistance between the stent and the outer catheter at the time of initial release is reduced by the restraint of the end of the stent. The reduction of the frictional resistance is very favorable for the release of the stent, especially the release in the ascending aorta. This is because after the delivery catheter passes through the aortic arch, a bend of approximately 180 degrees occurs, and the pushing direction of the push rod on the operator side and the moving direction on the ascending aorta side are almost opposite. Therefore, the smaller the frictional force between the stent and the outer catheter, the smaller the force required for the operator to push the push rod, and the operator can more easily control the release process and release the stent smoothly.

[0059] After at least a portion of the stent is released, the released portion of the stent can be compressed by moving one end of the stent toward the other end without moving the other end (e.g., pulling back the push rod without moving the inner and outer catheters), thereby closing the breach and supporting the true lumen of the blood vessel. Alternatively, the released portion of the stent can be expanded by moving one end of the stent away from the other end without moving the other end (e.g., moving the inner and outer catheters simultaneously without moving the push rod), thereby elongating the stent.

[0060] The manner of restraining both ends of the stent is not particularly limited, and any existing restraining manner that is ultimately removable can be used, for example, the stent can be temporarily fixed to the push rod and the inner catheter, respectively, via conventional stoppers.

[0061] The stent delivery system may have a normal outer diameter, facilitating placement of the stent via the femoral artery at the site of the aorta requiring treatment. According to the present invention, even a stent to be released into the ascending aorta can be assembled onto the delivery catheter by stretching the stent axially and compressing it radially to the appropriate diameter.

[0062] According to one embodiment, the outer catheter of the stent delivery system has an outer diameter of about 5-10 mm, for example, about 5-7 mm.

[0063] According to one embodiment, the push rod is hollow to allow a guidewire to pass therethrough.

[0064] A method for placing a full-length aortic stent using the above delivery system may include the steps of guiding the stent delivery system to a treatment site, at least partially releasing the stent, immobilizing one end of the released portion of the stent and manipulating the stent delivery system to move the other end of the released portion along the axial direction of the stent to compress / expand the released portion, and releasing the constraints on both ends of the stent after the stent is completely released.

[0065] According to the stent placement method, after the stent is released for a certain length, the position can be adjusted, for example, by pulling the push rod in a direction away from the heart while fixing the inner and outer catheter positions (the inner and outer catheters can be pulled in a direction away from the heart while fixing the positions of the push rods), thereby compressing (stretching) the semi-released stent in the axial direction. Such axial compression / stretching occurs because, in the stent delivery system, both ends of the stent are constrained, or a part of the stent has already been released and fixed in contact with the vessel wall, and when one end of the stent is fixed and the other end is moved, the released part of the stent is compressed / stretched in the axial direction. For a site with a tear in the blood vessel, the stent delivery system is used to compress the released stent segment until it obtains its maximum or appropriate metal coverage and maximum or appropriate radial support force, and the radial support force can firmly contact the vessel wall at the corresponding site (especially the site with the intimal tear), thereby completing the release of the segment.

[0066] Similarly, other parts of the stent can be directly and completely released or compressed / expanded while being partially released segment by segment as required, thereby adapting to the lesion locations and different structures and lengths in the aortic vessels of different patients to obtain optimal therapeutic effects. After the final release is essentially completed, the constraints on both ends of the stent are released, and the delivery catheter together with the push rod is removed from the vessel lumen.

[0067] The method for deploying a stent further includes the steps of detecting whether the release position is correct after at least partially releasing the stent, and if the release position is found to be incorrect, adjusting the stent delivery system so that the released portion is in the correct position, or retrieving the released portion into a delivery catheter and adjusting the stent delivery system to the correct position, and then releasing the stent again.

[0068] In the stent delivery system, both ends of the stent are temporarily restrained, so that the stent can be compressed or expanded segment by segment during the process of releasing the stent. In particular, for the cleft site of the inner wall of the blood vessel, the compression operation can effectively occlude the site and provide the necessary radial support to obtain the optimal therapeutic effect. At the same time, other or specific parts of the stent do not obstruct the blood flow, and do not create the risk of interruption or insufficient blood supply to the branch arteries.

[0069] Optionally, in one embodiment, in the branch artery region, the stretching operation can create larger mesh holes in the branch artery region to facilitate the placement of the branch stent in the branch vessel. In another embodiment, the stent is woven in an overlapping manner, so that any mesh hole can be expanded, and thus the branch stent can be placed by directly expanding the mesh hole.

[0070] According to one embodiment, the method further comprises introducing the stent delivery system through a femoral artery of a subject and removing the delivery catheter after stent placement.

[0071] According to one embodiment, the method further comprises guiding the stent delivery system to the treatment site with a guidewire.

[0072] According to one embodiment, said subject is a mammal, in particular a pig or a human, in particular a human, more particularly a human of the yellow race.

[0073] According to one embodiment, the method further comprises the step of placing at least one branch stent, in which the treatment site further comprises a branch vessel.

[0074] The present invention further provides a method of treating an aortic dissection or aortic aneurysm in a subject, said method comprising the step of placing the above-described stent or a stent and a branch stent in a stent kit at a treatment site in the aorta of the subject in need thereof according to the above-described stent placement method. [Brief description of the drawings]

[0075] [Figure 1] 1 is a schematic diagram of a stent for an entire length of an aortic vessel according to an embodiment of the present invention, and a schematic diagram of an entire length of an aortic vessel as an application example thereof. [Diagram 2] FIG. 2 is an enlarged view of a local portion of the stent shown in FIG. [Diagram 3] 1A-1C are schematic diagrams illustrating localized axial compression and axial expansion and radial compression of a stent according to an embodiment of the present invention. [Figure 4] 2 is a schematic diagram of a full length aortic vessel stent according to another embodiment. FIG. [Diagram 5] 1 is a schematic diagram of a stent according to an embodiment of the present invention; [Figure 6] 1 is a schematic cross-sectional view of a multi-layered stent wall according to an embodiment of the present invention. [Figure 7] 1 is a schematic diagram of a bifurcated stent in a stent kit according to an embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing placement of the branched stent A shown in FIG. 7. [Figure 9] 1 shows a stent delivery system according to an embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram of the semi-released state of the stent delivery system shown in FIG. [Figure 11] FIG. 1 is a schematic diagram showing the placement of a stent using a stent delivery system in a Type A aortic dissection lesion. [Figure 12] 2 is a schematic diagram showing the placement of a stent in an aortic intimal tear using a stent delivery system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0076] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the embodiments of the present invention and drawings. Obviously, the described embodiments are only some of the embodiments of the present invention, not all the embodiments, and the technical solutions described in the embodiments of the present invention can be implemented in any combination without conflict. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts are all included in the protection scope of the present invention.

[0077] Throughout this specification, unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. In case of conflict, the present specification shall prevail.

[0078] The same reference numbers in the drawings refer to the same parts. The shapes and sizes of parts in the exemplary drawings are merely illustrative and should not be considered as representing the actual shapes, sizes and absolute positions.

[0079] It should be noted that, in the present invention, the terms "comprises," "includes," or any other variations thereof are intended to cover a non-exclusive inclusion, whereby a method or apparatus comprising a set of elements not only includes the elements explicitly described, but also includes other elements not explicitly listed or elements inherent to the implementation of the method or apparatus.

[0080] It should be noted that the terms "first / second" in the embodiments of the present invention are merely used to distinguish between similar objects and do not represent a particular order of objects. It should be understood that "first / second" can be interchanged with a particular order or sequence, where permitted. It should be understood that objects distinguished by "first / second" can be interchanged under appropriate circumstances to allow the embodiments and examples of the present invention described herein to be practiced in an order other than that shown or described.

[0081] To more clearly describe the present invention, the terms "proximal end" and "distal end" are terms of common use in the field of interventional therapy, where "distal end" refers to the end that is farther from the heart during a surgical procedure, and "proximal end" refers to the end that is closer to the heart during a surgical procedure.

[0082] Stents The present invention provides a full length aortic vessel stent, the stent being braided with wires having at least two different diameters, the stent structure being configured to be compressible and expandable anywhere along the axial direction of the stent.

[0083] 1 is a schematic diagram of a stent according to one embodiment of the present invention and an aortic blood vessel to which the stent is applied. As shown in the figure, a stent 1 is applied to an aortic blood vessel 900. The stent 1 includes a stent body 2 and a cavity 9 surrounded by the stent body 2. The stent 1 shown in FIG. 1 is bent into the same shape as the aorta, but the actual stent 1 has a straight cylindrical shape with one end thick and the other end thin when no external force is applied.

[0084] Further referring to Figure 2, there is shown an enlarged view of the local stent body of the stent 1 shown in Figure 1. The stent body 2 of the stent 1 is formed by overlapping and braiding a plurality of first wires 3 and a plurality of second wires 4. Thus, the stent is a bare stent. The local stent body shown in Figure 2 is a single-layer mesh structure having mesh holes 5.

[0085] The stent may further have a multi-layer structure, such as 2 to 4 layers, for example, by forming multiple layers using a back-knit method.

[0086] The stent has a diameter that gradually narrows from 50 to 60 mm (eg, about 55 mm) to 30 to 10 mm (eg, about 20 mm) since it is applied to the entire aortic blood vessel from the ascending aorta to the abdominal aorta.

[0087] According to the present invention, the stent 1 can be braided with a total of 48 to 202 wires. For example, the stent may be braided with 48, 64, 96, 128, 156, or 196 wires. The number of wires can be determined based on the diameter of the stent, the number of layers, the material of the wires used, etc.

[0088] The material used for the stent may be any suitable material used for peripheral vascular stents, so long as it can provide sufficient radial support and has a certain degree of fineness. In general, it is preferable to use metal wires such as nickel-titanium alloy wires, cobalt-chromium alloy wires, tungsten wires, and tantalum wires, and more preferably nickel-titanium alloy wires.

[0089] The number of the second wires 4 as thick wires is at least 4, not more than 32, and usually not more than 30. The diameter of the second wire 4 is 150-800 μm, preferably 150-600 μm, for example, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm or 600 μm. The second wire 4 provides the stent 1 with basic support and complete structure. However, the number of the second wires should not be too large. For example, even if only a 300 μm diameter wire is adopted, if the number of wires is about 32, it cannot be compressed to a suitable delivery size, especially in the case of a super-large diameter stent portion exceeding about 40 mm, and cannot be used.

[0090] In the stent 1, all wires except the thick wire are the first wires 3 as thin wires. The first wires 3 may have a diameter of 20 to 150 μm, preferably 50 to 150 μm, for example, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, and 150 μm. The first wires 3 supplementarily support the stent 1 and fill the gaps of the second wires 4. In addition, the first wires 3 are far more numerous than the second wires 4, and therefore exert an effect of maintaining the shape of the stent 1. The inventor has found that, although it seems logically possible, in reality, when the overlapping weave braiding method is adopted, a large-diameter stent having a specific shape and sufficient supporting force cannot be formed only by the second wires (i.e., thick wires). On the other hand, a large diameter stent formed by fixing the wire-wire intersections, for example using laser engraving technology, has a much smaller supporting force even though the wire diameter is the same, and cannot meet the requirements for aortic vessels.

[0091] The stent 1 is braided by overlapping weaves, and regular relative movement can occur at the crossing points of the wires, so that any mesh hole 5 on the stent 1 can be easily expanded or compressed.

[0092] FIG. 3 exemplarily shows that one end of a local segment 8 of stent 1 is fixed while the other end is moved along the axis AA to obtain a compressed segment 8' by axial compression, or an expanded segment 8'' by axial expansion.

[0093] The "axial direction" of the stent referred to in this specification refers to the direction along AA shown in Fig. 3, which is the direction of the central axis of the cylindrical shape of the stent. The "radial direction" of the stent referred to in this specification refers to the direction along DD shown in Fig. 3, which is the direction of any one diameter of the cylindrical circle of the stent. Generally, in this specification, "compression along the radial direction" refers to compression from the circumference to the center.

[0094] The above-mentioned properties of the stent of the present invention can provide a variety of advantages.With further reference to Figure 3, a schematic diagram of axial compression and expansion of a local segment 8 of the stent 1 shown in Figure 1 is shown.

[0095] Because the stent is axially expandable, the braided wires, especially the second wire, have a significantly reduced density per unit length. Thus, a properly expanded extension segment 8'' is easily radially compressed into a small diameter delivery configuration 8''', which allows it to be assembled into a delivery system having a conventional outer diameter (e.g., 5-10 cm, preferably 5-7 cm). Thus, the stent solves the problem in the prior art that large size, high support stents cannot be mounted into a delivery system having a suitable diameter.

[0096] Furthermore, the stent has axially compressible and expandable properties, allowing the length of the stent to be adjusted during the deployment process, thereby allowing it to adapt to the aortic anatomy and length of any patient.

[0097] Most importantly, since the stent is axially compressible, the compressed stent can form a high metal coverage and obtain a high radial support force due to the increased density of the second wire per unit length. The high radial support force can effectively expand the stenosed blood vessel, and the high metal coverage can obtain a very low fluid permeability, thereby effectively blocking the damaged part of the vascular intima. At this time, the second wire 4 plays the role of supporting the framework, and the first wire 3 fills the gap between the second wires 4 and acts like a woven membrane of the stent graft. Unlike a stent graft, the stent can provide a fairly high radial support force after being axially compressed, and can also be effectively used in the treatment of type A aortic dissection involving the ascending aorta. Therefore, the stent also solves the problem that the conventional high-density mesh stent or stent graft is difficult to apply to the ascending aorta. Since any part of the stent of the present invention is compressible, the tear forming the aortic dissection can be targeted and blocked during the placement of the stent, regardless of its location.

[0098] The stent 1 has a radial supporting force of 100N or more, preferably 100 to 600N in a naturally released state, and has a radial supporting force of 400N or more, preferably 400 to 1000N in a maximum axially compressed state.

[0099] The "naturally released state" of the stent referred to in this specification refers to a state in which the stent is released without being axially compressed when the stent is fixed in water at 37±2°C.

[0100] The "maximum axially compressed state" of a stent referred to in this specification refers to a state in which the stent is compressed to the point where it cannot be compressed axially in a naturally released state.

[0101] The "radial support force" of a stent as referred to herein refers to the force required to compress the stent, in its natural released state, diametrically to 85% of its original diameter after fixation.

[0102] In response to the radial support force, the stent needs to have a high degree of liquid impermeability in order to effectively seal tears in the vascular intima. This property can be expressed as a metal coverage rate. The stent according to the embodiment of the present invention can have a metal coverage rate of 30 to 90% in a naturally released state, and a metal coverage rate of 80 to 100%, preferably 80 to 95%, in a maximum axial compression state.

[0103] The "metal coverage" of a stent referred to herein refers to the percentage of metal coverage per unit area as measured by scanning with an electron microscope.

[0104] According to one embodiment, the stent can have a radial support force of 200N or more in a naturally released state and a metal coverage rate of 30 to 60%. In this embodiment, the braid density of the stent is relatively low, and the radial support force of the stent in the naturally released state is also relatively low. The stent in this embodiment has a high axial compression rate, and can obtain the necessary radial support force and metal coverage rate even after compression. When placing, it is necessary to release a relatively long one-stage stent and then compress it, which requires the blood vessel to have a relatively long straight portion, and therefore is not suitable for a blood vessel such as the ascending aorta that has a bend.

[0105] According to another embodiment, the stent can have a radial support force of 100N or more in a naturally released state, and a metal coverage rate of 60-90%, preferably 70-90%. In this embodiment, the braid density of the stent is relatively high, and the radial support force of the stent is also relatively high in a naturally released state. The axial compression rate of the stent in this embodiment is low, and after being released, a certain radial support force and metal coverage rate can be obtained without compression. It is suitable for blood vessels such as the ascending aorta, which have a short straight portion.

[0106] Thus, according to one embodiment, the stent 1 can have different metal coverage and radial support in different segments, which can be achieved by different braiding schemes or by providing different numbers of layers.

[0107] Continuing with reference to FIG. 1, several branch stent fixing mechanisms 6 are provided in the cavity 9 of the stent 1. As shown in the figure, the branch stent fixing mechanisms 6 are provided in the cross section of the cavity 9 perpendicular to the inner wall of the stent body 2. In order to fix the branch stent placed in the branch arterial blood vessel, the position of the branch stent fixing mechanism 6 corresponds to the position of the main branch blood vessel on the aortic blood vessel 900. The stent 1 shown in FIG. 1 is provided with three branch stent fixing mechanisms 6, which correspond to the three branch arteries in the aortic arch portion, the left and right renal arteries in the abdominal aorta portion connected to both kidneys, and the celiac trunk artery and superior mesenteric artery, respectively. Of course, the number of branch stent fixing mechanisms may be one to three according to specific needs.

[0108] Each of the branch stent fixing mechanisms 6 has two or three circular holes 7. The number of circular holes 7 corresponds to the number of branch arterial vessels to be further treated near the branch stent fixing mechanism 6. As can be seen from the structure of the branch stent detailed below, the inner diameter of the circular holes 7 of the branch stent fixing mechanism 6 is adapted to the outer diameter of the fixing part of the branch stent (e.g., slightly smaller than the outer diameter of the fixing part of the branch stent), so that the branch stent can be firmly fixed.

[0109] According to the present invention, the branch stent anchoring mechanism 6 is integrally braided with the stent body 2, thereby fixedly connecting it to the inner wall of the stent body 2. The branch stent anchoring mechanism 6 can be made of the same material and braiding method as the stent body 2. Alternatively, unlike the stent body 2, the branch stent anchoring mechanism 6 can be braided with wires of only one diameter, or, like the stent body 2, it can be braided with wires of different diameters, but in a relatively loose braid, which makes it easier to compress the mechanism into a suitable delivery configuration while still ensuring stable anchoring of the branch stent.

[0110] FIG. 4 shows a schematic diagram of a stent 10 according to another embodiment of the present invention. The stent 10 has a structure similar to that of the stent 1 shown in FIG. 1, that is, it has a stent body 12 and a cavity 19 surrounded by the stent body 12. The cavity 19 is provided with three branch stent fixing mechanisms 16 having circular holes 17 for fixing the branch stents. Unlike the stent 1, the stent 10 has branch segments at its distal end corresponding to the left and right iliac arteries, namely, a first iliac artery segment 18-1 and a second iliac artery segment 18-2. As shown in the figure, the first iliac artery segment 18-1 is significantly longer than the second iliac artery segment 18-2. As will be seen from the stent placement method described later, the stent can be inserted and placed in the aorta via the femoral artery using a normal-sized delivery system. Therefore, the first iliac artery segment 18-1 is suitable for placement in the iliac artery on the side where the stent is inserted, and the relatively short second iliac artery segment 18-2 is suitable for placement in the iliac artery on the other side. The specific placement method can be selected according to the vascular condition of the patient. According to another embodiment, the first iliac artery segment 18-1 and the second iliac artery segment 18-2 may have the same length.

[0111] According to one specific embodiment of the present invention, the length of the first iliac artery segment 18-1 (first branch) may be 50 to 200 mm, and the length of the second iliac artery segment 18-2 (second branch) may be 50 to 200 mm. If it is necessary to place a stent in the extension part of the iliac artery on the side where the second iliac artery segment 18-2 is placed, away from the heart, an appropriate stent can be placed in the end of the second iliac artery segment 18-2 after placing the stent 10. The present invention is not particularly limited to the additional stent to be placed, and it may be a bare stent or a stent graft.

[0112] According to one embodiment, the stent is braided by three or more wires having different diameters. As shown in FIG. 6, a local enlarged schematic diagram of a single layer of the stent of the embodiment is shown. The stent is braided by one type of wire, the first wire 33, and two types of wires, the second wires 34a and 34b. Here, the first wire 33 is a thin wire and can have a diameter of 20 to 150 μm, preferably 50 to 150 μm. The second wire includes a first thick wire 34a that can have a diameter of 150 to 300 μm and a second thick wire 34b that can have a diameter of 300 to 600 μm. Here, 6 to 12 first thick wires can be used, and 4 or more but not more than 12 second thick wires can be used, and the rest are first wires. This embodiment may also have other variations, for example, but is not limited to, a stent made of two types of first wires (e.g., having diameters in the ranges of 20-100 μm and 100-150 μm, respectively) and one type of second wire, or a stent made of two types of first wires and two types of second wires.

[0113] A stent formed with three or more different diameter wires provides more uniform radial support throughout the stent and also improves the flexibility of the stent.

[0114] As mentioned above, the stent has multiple layers, preferably 2, 3 or 4 layers. According to a preferred embodiment, a multi-layer stent can be formed by back-knitting a single layer braided mesh. As shown in Fig. 6A-C, schematic cross-sectional views of stent walls with 2-4 layers are shown. Fig. 6A shows a two-layer structure, in which the upper layer 42 of the structure in the figure is located inside the stent and the lower layer 44 is located outside the stent (i.e., the side in contact with the vessel wall). Back-knitting forms a smooth end opening at the proximal end 41 of the structure. At the distal end 43, the lower layer 44 toward the outside of the stent is back-knitted for a certain distance to wrap the opening edge (burr) of the upper layer 42 on the inside of the stent toward the distal end inside the lower layer 44. This forms a smooth end opening at both ends. Similarly, in Fig. 6B, the upper layer 52 is back-knitted at the proximal end 51 to form the lower layer 54, and is further back-knitted at the distal end 53 to form the middle layer 56. The bottom layer 54 and the middle layer 56 at the distal end 53 are slightly longer than the top layer 52 so that the open edge of the distal end of the top layer is located inside the stent. In this way, both ends of the stent have smooth end openings. The same is true for the four-layer case in FIG. 6C, where the inner two layers 62, 68 of the stent are shorter than the edges formed by the back-knit of the outer two layers 64, 66 of the stent at the distal end 63, and at the proximal end 61, the top layer 62 is back-knit to form the bottom layer 64, enclosing the two middle layers 68 and 66 therebetween. As a variant, only a small portion of the distal end of the top layer 62 or the middle layer 68 can be back-knitted to enclose the open edge of the other layer therein. In this way, both ends of the stent have completely smooth end openings.

[0115] The stent is preferably in a multi-layer form, which allows both ends (particularly the proximal end) of the stent to form smooth end openings and prevents secondary damage to the blood vessel due to the open edges of the braid.

[0116] The above stent has been described in detail with examples. As can be understood by those skilled in the art, the above examples are not intended to limit the scope of the present invention, but are intended to illustrate the advantages of the stent, and the features in the examples can be applied independently or in combination to the stents of other examples under appropriate circumstances. Any obvious variations and modifications made by those skilled in the art to the stent based on the disclosure of this specification are also included in the scope of the present invention as long as they conform to the concept of the present invention.

[0117] Stent Kit The present invention further provides a stent kit, comprising the above-described stent and a matching bifurcated stent.

[0118] The branched stent used in the stent kit of the present invention may be a stent commonly used in the prior art, so long as the portion to be fixed (in other words, the portion remaining in the lumen of the aortic stent) has an outer diameter that fits the circular hole of the branched stent fixing mechanism of the stent of the present invention. The branched stent may be braided with at least two wires of different diameters, or may be braided with only one wire of different diameter, and the present invention is not particularly limited thereto. Preferably, the material for braiding the branched stent is the same as the material of the aortic stent described above.

[0119] Figure 7 shows the schematic diagrams of two preferred bifurcated stents. As shown in the figure, A and B are bifurcated stents 80 and 90, respectively, which are applied to two specific embodiments of the stent kit of the present invention. As shown in the figure, both bifurcated stents 80, 90 are bare stents and are braided by a single diameter metal wire.

[0120] The branch stent 80 shown in FIG. 7A includes a support portion 81 for supporting a branch blood vessel and a fixing portion 82 for fixing the branch stent to the branch stent fixing mechanism 6, 16 in the cavity of the aortic stent 1, 10. The support portion 81 and the fixing portion 82 have the same diameter. An opening 83 is formed in the stent wall between the two portions. As shown in FIG. 8, when the branch stent 80 is placed in an aortic blood vessel 900 having a branch arterial blood vessel 990 in combination with a stent 1 (only a portion is shown), the support portion 81 passes through one mesh hole of the stent 1 to insert into and support the branch arterial blood vessel 990, and the fixing portion 82 extends into the cavity of the stent 1 and passes through one circular hole 7 of the fixing portion 6 of the branch stent. The opening 83 of the branch stent 80 and the end port 84 at the end of the fixing portion of the branch stent form a blood flow passage through both ends of the fixing portion 82, which makes the blood flow in the aorta smoother.

[0121] Further, please refer to the branch stent 90 shown in FIG. 7B. The branch stent 90 also includes a support portion 91 and a fixing portion 92, but the diameter of the support portion 91 is smaller than that of the fixing portion 92. In this embodiment, the diameters of the support portion 91 and the fixing portion 92 are respectively suitable for the inner diameter of the branch arterial vessel to be supported and the inner diameter of the circular hole 7, 17 in the branch stent fixing mechanism 6, 16 in the aortic stent 1, 16. Also, unlike the branch stent 80, the branch stent 90 has an included angle α between the support portion 91 and the fixing portion 92. The included angle α matches the angle between the branch arterial vessel and the aortic vessel in which the branch stent is placed. Such a method of dividing the branch stent into two parts with a certain included angle can maximize the elimination of the restoring force of bending deformation caused by the placement of the branch stent and can better adapt to the structure of the blood vessel itself. Similar to the branch stent 80, the branch stent 90 has an opening 93 at one end where the fixing part 92 and the support part 91 are connected. The opening 93 and the end port 94 of the fixing part 92 form a through channel in the fixing part 92 through which blood can easily pass.

[0122] Of course, the branched stent in the stent kit is not limited to the specific shape shown in Fig. 7. For example, the branched stent used in the stent kit may have the shape of A or B in Fig. 7, but may not have the openings 83, 93, or may be a stent graft having openings, or may be a semi-covered, semi-bare stent in which the support part is covered and the fixation part is not covered, etc.

[0123] The number of branch stents in the stent kit may be multiple, for example, 2, 3, 4, 5, 6, or 7 or even more. Each stent may have different configurations to accommodate the structures and treatment requirements of different branch arterial vessels. Not all of them are listed in detail here.

[0124] STENT DELIVERY SYSTEM AND METHOD FOR PLACING A STENT - Patent application The present invention further provides a stent delivery system, in which the above-mentioned stent is assembled to the system in a delivery configuration, and both ends of the stent are constrained and only after all other portions of the stent have been released, the constraints are released and the stent is fully released.

[0125] 9, there is shown a schematic diagram of a semi-released stent delivery system 100 in accordance with the present invention. The stent delivery system 100 comprises a delivery catheter 120 and a stent 150.

[0126] The delivery catheter 120 includes an outer catheter 130, an inner catheter 140, and a push rod 170, which are arranged coaxially from outside to inside along a longitudinal axis XX. The delivery catheter 120 has a distal end 123 and a proximal end 122. The delivery catheter 120 further has a hemostatic valve 125. The outer catheter 130 has a proximal end 180 and a distal end 190, and a first lumen 133 runs through the entire outer catheter 130. The inner catheter 140 is arranged coaxially with the outer catheter 130 along the longitudinal axis XX within the first lumen 133 at its distal end 190 and has a second lumen 143. The push rod 170 extends through the first lumen 133 of the outer catheter 130 and through the second lumen 143 of the inner catheter 140 to the outside of the end port 135 at the distal end of the outer catheter. The push rod 170 may have a third lumen (not shown) for the passage of a guidewire.

[0127] At the proximal end 180 of the outer catheter 130, the stent 150 is releasably maintained in a delivery configuration in a first lumen 133 between the push rod 170 and the outer catheter 130. A first restraint 161 restrains the proximal end 154 of the stent 150 to the proximal end of the push rod 170. The first restraint 161 may be a conventional stopper and may be removed from the stent 150, when necessary, thereby releasing the proximal end 154 of the stent 150. A second restraint 162 restrains the distal end 156 of the stent 150 to the proximal end of the inner catheter 140. Similarly, the second restraint 162 may be a conventional stopper and may be removed from the stent 150, when necessary, thereby releasing the distal end 156 of the stent 150.

[0128] 10, the stent delivery system 100' shown in Figure 9 is in a semi-released state. In Figure 10, the proximal end 131 of the outer catheter 130 in the delivery system 100' can be separated from the proximal end 122 of the delivery catheter 120, and the outer catheter 130 is caused to move relative to the inner catheter 140 and push rod 170 by holding the outer catheter stationary and pushing the push rod 170 toward the proximal end (or holding the inner catheter and push rod stationary and pulling the outer catheter 130 toward the distal end).

[0129] 10 , by pushing the push rod 170 towards the proximal end 122, actuation of the push rod 170 causes the proximal end 122 of the delivery catheter 120, the stent 150 coupled to the end of the push rod 170, and the inner catheter 140 coupled to the stent 150 to move proximally relative to the outer catheter 13. In this manner, the stent 150 begins to release from its proximal end 154.

[0130] Since the proximal end 154 of the stent 150 is restrained during the release process, the released segment does not reach its natural released diameter and does not contact the vessel wall. This not only makes it easier to adjust the stent position, but also allows the stent 150 to be retrieved back into the outer catheter 130 and released again after adjusting the position. In addition, the restraint of the proximal end 154 of the stent 150 is also advantageous in reducing the frictional force during the initial release, which is advantageous for a smooth release. This is especially important for surgery that involves distal manipulation in narrow vessels.

[0131] The stent delivery system is particularly advantageous for the treatment of Type A aortic dissection.

[0132] Referring to Fig. 11, a schematic diagram of placing a stent 150 in a type A aortic dissection lesion using a stent delivery system 100 according to an embodiment of the present invention is shown to illustrate the therapeutic benefits of the stent delivery system for type A aortic dissection. Fig. 11 shows that a cleft 903 exists in the ascending aorta 910, resulting in the formation of a false lumen 902 extending from the ascending aorta 910 through the aortic arch 920 to the descending aorta 930. The stent delivery system 100 is guided into the true lumen 91 of the aorta by a guide wire 101. To start the release of the stent 150, the operator pushes the push rod 170 toward the proximal end, where the pushing force is indicated by f1 and the direction of the pushing force is indicated by an upward arrow along the descending aorta. The pushing force f1 is transmitted to the proximal end 122 of the delivery catheter along the push rod 170, but at this time, the delivery system 100 is bent by approximately 180° after passing through the aortic arch 920, and the direction of the force f2 acting on the proximal end 122 of the delivery catheter is approximately opposite to the direction of the pushing force at f1 (as shown by the arrow). As a result, it becomes difficult to control the magnitude of the pushing force required for the initial release. In the stent delivery system 100, referring to FIG. 10, the proximal end of the stent 150 is temporarily restrained by a member such as a stopper at the proximal end of the push rod 170, thereby greatly reducing the outward expansion force of the stent 150 at the proximal end, thereby reducing the friction force between the stent 150 and the inner wall of the outer catheter 130. Therefore, the delivery system 100 greatly reduces the pushing force required for the initial release of the stent, and the proximal end of the push rod 170 can be pushed out of the outer catheter 130 relatively easily.

[0133] 12, a schematic diagram of a stent being placed in an intimal cleft of the aorta using a stent delivery system is shown. In FIG. 12A, a portion of an aortic vessel 900 is illustratively shown including an intimal cleft 903, which causes intimal tearing to form a false lumen 902. The stent delivery system 100 is guided to the cleft 903 and releases a portion of the stent 151 by pushing the push rod in the direction shown by the arrow while keeping the outer catheter 130 in place. With further reference to FIG. 12B, by pulling back the push rod in the direction shown by the arrow while keeping the inner and outer catheters of the delivery system 100 in place, the released stent segment 151 is pushed back until it abuts the region of the vessel where the intimal cleft 903 is located, forming a compressed segment 151'. When a stent is designed, the diameter of the stent is typically designed to be slightly larger than the diameter of the blood vessel at the placement site, so that the compressed segment 151' firmly abuts against the inner wall of the blood vessel at that portion, sealing the cleft 903 and expanding the true lumen of the blood vessel at that portion. Due to the inward contraction force of the blood vessel wall, the compressed segment 151' remains within the blood vessel at that portion in its compressed shape.

[0134] Next, as shown in FIG. 12C, the remaining stent segment 152 is further released by pulling the outer catheter 130 toward the distal end in the direction indicated by the arrow in the drawing (the inner catheter 140 and the push rod 170 remain stationary). Finally, when the stent 150 is completely released, the restraints on both ends of the stent by the stoppers are released, thereby releasing the entire stent 150 to the treatment site, and the delivery catheter is removed from the blood vessel (see FIG. 12D). The stent 150 placed at the lesion site has two segments, one is a compressed segment 151' and the other is a natural release segment 152. Here, the compressed segment 151' exerts an effect of sealing the cleft 903 and has a relatively strong radial support effect on the blood vessel, while the natural release segment 152 has an appropriate support effect on the other parts of the blood vessel and does not obstruct blood flow, especially to the branch vessels.

[0135] In accordance with the present invention, the position of the stent can be verified after the stent segment 151 is released (i.e., when it is in the state shown in FIG. 12A) so that the segment after compression can accurately seal the cleft 903. If the position is not ideal, adjustments can be made and the released segment 151 can even be retrieved back into the outer catheter and the position of the delivery system adjusted before being released again.

[0136] Similarly, the stent position can be checked after any segment is released, so that an optimal placement effect can be obtained. Finally, before releasing the constraints on both ends of the stent, the stent position is checked again, because at this time, the stent can be retrieved and released again if the placement position is not ideal. Once the constraints on both ends of the stent are released, the stent position cannot be adjusted.

[0137] Furthermore, the compression method of other segments of the stent is similar to that shown in FIG. 12B. For example, after the front part of the stent is released and abuts against the vessel wall, a part of the stent is subsequently released. Since the end of the subsequently released stent is restrained by the outer catheter, the outer catheter and the inner catheter are moved simultaneously to the proximal end without moving the push rod, so that the newly released part of the stent that has not yet abutted against the vessel wall is compressed to abut against the vessel wall, forming a part of a segment with high metal coverage and high radial support.

[0138] The above examples have described the detailed scheme of the stent delivery system and the method of placing a stent in a blood vessel using the system. Those skilled in the art can easily make modifications and alterations based on the above content to meet the actual application requirements without departing from the spirit of the present invention, and such modifications and alterations are also included in the scope of the present invention.

[0139] Example 1 This embodiment provides a stent with the structure shown in Figure 1, which is used in the area of ​​the descending aorta. The stent is made of nickel-titanium alloy material and is braided by 54 first wires with a diameter of 100 μm and 12 second wires with a diameter of 400 μm. The stent is braided in a total of two layers in a back-knit manner. The back-knit manner is as shown in Figure 6A, where the proximal end is a back-knitted smooth end and the distal end is a two-layer burr, where the outer burr is slightly back-knitted and the inner burr is located inside the back-knitted part to avoid the burr being exposed and damaging the vascular wall.

[0140] The stent is cone-shaped, with a proximal diameter of 45 mm, a distal diameter of 32 mm, and a length of 8 cm. After being released in the blood vessel, the stent can reach a maximum fixed length of 24 cm.

[0141] According to the detection by scanning electron microscope, the stent of this embodiment has a metal coverage of 40% in the natural state, and the metal coverage after the maximum axial compression is about 90%. When tested by a radial support strength tester, the stent of this embodiment has a radial support strength of 350N in the thicker part in the natural state, and the radial support strength of each part after the maximum axial compression is all more than 400N, even more than 600N.

[0142] In addition, to simulate the axial bending force of the stent when fixed to the aortic arch, the radial restoring force of the stent was measured to be 0.4 to 1.0 N.

[0143] Example 2 This embodiment provides a stent with the structure shown in Figure 3, which is used in the region from the ascending aorta to the aortic arch. The stent is made of nickel titanium material and is braided by 120 first wires with a diameter of 100 μm and 8 second wires with a diameter of 400 μm. The stent is braided in a total of four layers in a back-knit manner. The back-knit manner is as shown in Figure 6C, where the proximal end is a completely back-knitted smooth end, and at the distal end, two layers of burrs are located inside the stent and two layers of back-knit edges are located outside the stent, which avoids the burrs being exposed and damaging the vascular wall.

[0144] The portion of the stent corresponding to the ascending aorta has a diameter of 45 mm and a length of 9 cm, and the portion of the stent corresponding to the aortic arch has a diameter of 32 mm and a length of 6 cm.

[0145] According to the detection by scanning electron microscope, the stent in this embodiment has a metal coverage of 80% in the natural state, and a metal coverage of 98% after the maximum axial compression. When tested by a radial support force tester, the stent in this embodiment has a radial support force of about 400N corresponding to the thicker part of the ascending aorta in the natural state, and the radial support forces after the maximum axial compression are all more than 400N, even more than 500N.

[0146] In addition, to simulate the axial bending force of the stent when fixed to the aortic arch, the radial restoring force of the stent was measured to be 0.4 to 1.0 N.

[0147] The above description is merely some specific embodiments of the present invention, and is not intended to limit the scope of the claims of the present invention. Based on the concept of the present invention, equivalent structural transformations made using the contents of the specification and drawings of the present invention, or direct / indirect application to other related technical fields, are all intended to be included in the scope of patent protection of the present invention.

Claims

1. A full-length aortic stent having a stent body and a lumen surrounded by the stent body, The stent has a length of 200 to 600 mm and an outer diameter that gradually tapers from 60 to 30 mm to 30 to 10 mm, the stent body is braided with wires having at least two different diameters, and has a structure that is compressible and extensible at any site along the axial direction of the stent in a released state, the first wire has a diameter of 20 to 150 μm, the second wire has a diameter of 150 to 800 μm, and at least one branch stent fixing mechanism is provided within the cavity. A stent for use in the entire aorta.

2. The stent has a metal coverage of at least 30% and a radial support force of 100 N or more in a naturally released state, and preferably has a metal coverage rate of 30 to 90% and a radial support force of 100 to 600 N.

2. The stent of claim 1.

3. The stent has a metal coverage of at least 80% and a radial support of 400N or more in a released and axially compressed state, and preferably has a metal coverage of 80-100% and a radial support of 400-1000N in a released and axially compressed state. The stent of claim 2.

4. the branch stent fixing mechanism is provided in a segment of the stent lumen corresponding to a main branch vessel close to the aortic arch and / or abdominal aorta, and is configured to have at least one circular hole for fixing the branch stent, the circular hole being perpendicular to an inner wall of the stent body; 2. The stent of claim 1.

5. the branch stent fixation mechanism is integrally braided with the stent body; 5. The stent of claim 4.

6. The stent body is braided in an overlapping weave manner to make each mesh of the stent body stretchable and compressible.

2. The stent of claim 1.

7. The stent further comprises a bifurcation segment corresponding to the left and right common iliac arteries.

2. The stent of claim 1.

8. the first wire has a diameter of 50-150 μm and the second wire has a diameter of 150-600 μm; the stent is braided with 48-202, preferably 48-156, more preferably 48-128 wires, the second wire being 4-32 and the remainder being first wires; A stent according to any one of claims 1 to 7.

9. the at least two different diameter wires are three different diameter wires, the second wires include a first thick wire and a second thick wire of different diameters, the first thick wire has a diameter of 150-300 μm, the second thick wire has a diameter of 30-600 μm, the stent is braided with 48-202 wires, the second wires include 6-24, preferably 6-12, first thick wires and 4-24, preferably 6-12, second thick wires, with the remainder being first wires, provided that the total number of the first thick wires and the second thick wires does not exceed 30; A stent according to any one of claims 1 to 7.

10. the at least two different diameter wires are three different diameter wires, the first wires include first and second thin wires of different diameters, the first thin wires have a diameter of 50-100 μm and the second thin wires have a diameter of 100-150 μm, the stent is braided with 48-202 wires, the second wires are 4-30 and the remainder are first wires, the first wires include 32-166, preferably 32-120, of the first thin wires and 32-166, preferably 32-120, of the second thin wires, provided that the total number of the first thin wires and the second thin wires does not exceed 198, preferably 152; A stent according to any one of claims 1 to 7.

11. The stent body has 1 to 4 layers of braided mesh, and preferably the end of the stent body has 2 to 4 layers of braided mesh.

2. The stent of claim 1.

12. The material of the first wire and the second wire is a medical metal or alloy.

2. The stent of claim 1.

13. A stent kit for the entire aorta, comprising a stent according to any one of claims 1 to 12 and at least one branch stent.

14. the branch stent includes a support portion and a fixing portion, the support portion being configured to be located in a corresponding branch arterial blood vessel and support the corresponding branch arterial blood vessel after the branch stent is placed, and the fixing portion being configured to be located in a lumen of the stent and fixed by the branch stent fixing mechanism after the branch stent is placed. The stent kit of claim 13.

15. An opening is provided on a side wall of the fixation portion of the branch stent, and the opening is configured to allow blood in the aorta to pass through the fixation portion without being obstructed after the branch stent is placed in the branch artery blood vessel. The stent kit of claim 14.

16. 1. A stent delivery system comprising: a delivery catheter including an outer catheter, an inner catheter, and a push rod, arranged coaxially from outside to inside; the outer catheter having a proximal end and a distal end and a first lumen extending therethrough; the inner catheter having a second lumen extending within a first lumen at a distal end of the outer catheter and extending through the inner catheter; the push rod extends through a first lumen of the outer catheter and a second lumen of the inner catheter and exits from a distal end of the inner catheter; The stent delivery system further comprises a stent according to any one of claims 1 to 12, wherein in a delivery configuration, the stent is releasably held between the push rod and the outer catheter and is located within a first lumen at a proximal end of the outer catheter.

17. The outer diameter of the stent delivery system is 5-10 mm, preferably 5-7 mm.

17. The stent delivery system of claim 16.

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