A bare stent compressible in the axial direction

Abstract

The present application relates to an axially compressible bare stent. The bare stent is used for the aorta, and is formed by overlapping and interweaving at least two first wires and second wires of different diameters. In the natural release state, the bare stent has a metal coverage of at least 30%, wherein the first wire has a diameter of 20 to 150 μm, and the second wire has a diameter of 150 to 600 μm. The bare stent of the present invention is used to treat aortic aneurysms and / or aortic dissection lesions, and through the axial compressibility of the stent, it provides low permeability and strong radial support force in the aorta where it is needed.

Description

Technical Field

[0001] The present invention relates to a bare stent, and in particular to a bare stent used for treating aortic diseases such as aortic aneurysm or aortic dissection. Background Art

[0002] The arterial wall is composed of the intima, media, and adventitia that fit tightly together. When the inner wall of the artery is partially damaged, the media of the arterial wall gradually peels off under the strong impact of arterial blood flow, allowing blood to enter between the media and adventitia of the blood vessel wall, forming two true and false cavities. The most common is aortic dissection. Aortic dissection weakens the arterial wall and is at risk of rupture at any time. Once the dissection ruptures, it will cause the patient's death within a few minutes.

[0003] Aortic dissection is divided into type A and type B according to the site and extension of the intimal tear (ie, Stanford classification). Type A refers to lesions involving the ascending aorta, where the arterial wall dissection starts from the ascending aorta, and can also occur in the aortic arch or the proximal part of the descending aorta but involves the ascending aorta. Type B refers to the site of arterial wall dissection occurring in the descending aorta, not exceeding the proximal end of the opening of the left subclavian artery.

[0004] Aortic aneurysm is an abnormal dilation of the aorta. A rupture of an aortic aneurysm can be fatal.

[0005] Therefore, early diagnosis and timely treatment of aortic dissection and aortic aneurysm are very necessary.

[0006] Currently, there are three common options for the treatment of aortic dissection or aortic aneurysm.

[0007] One option is to use open surgery to replace artificial blood vessels. This option is currently used for type A aortic dissection. Its disadvantages are high intraoperative mortality, residual dissection (i.e. type B dissection) after surgery, and the proportion of patients who need reoperation within 10 years is as high as 9-67%. In addition, the cost of treatment is very high, and relatively few hospitals have mastered this surgical technique. In addition, open surgery is not suitable for all patients, so the proportion of patients who can benefit from this option is very small.

[0008] Another option is EVAR, which is also known as covered stent implantation. This option has the advantages of less trauma, faster recovery, and low mortality, but because the stent placement site often involves the aortic arch and / or abdominal aorta, the three major branch arteries on the convex side of the aortic arch, as well as the main branch arteries such as the left renal artery, right renal artery, celiac trunk, and superior mesenteric artery in the abdominal aorta cannot be blocked during and after the entire operation. The conventional practice is to make a hole on-site at the site of the covered stent corresponding to the important branch artery. On the one hand, this increases the difficulty of the operation and requires experienced surgeons to implement it; on the other hand, if the positioning is inaccurate during placement, or the stent shifts during the release process, blocking important branch blood vessels will cause serious consequences. In addition, if the stent is modified before the operation, the manufacturer may refuse to provide warranty services on this basis.

[0009] The third option is a recently proposed total aortic endovascular intervention using a dense mesh stent. Unlike the EVAR endovascular intervention, this option does not use a mechanical occlusion mechanism for the false lumen, and the dense mesh stent does not significantly hinder blood flow. Instead, it achieves the purpose of treatment by forming an obstruction to blood flow on the inner wall of the diseased blood vessel, changing the hemodynamics in the false lumen, reducing the pressure therein, and promoting intraluminal thrombosis. Compared with the EVAR endovascular intervention, this option uses a dense mesh stent, which not only has the advantages of less trauma, faster recovery, and lower mortality, but also the dense mesh stent will not significantly block blood flow to the branch arteries, thereby greatly reducing the difficulty of the operation. Therefore, doctors with ordinary experience can implement it.

[0010] However, the therapeutic effect of this type of stent is not ideal, because the rupture of the vascular wall is not completely blocked, and an ideal intraluminal thrombus cannot always be formed. In addition, the current dense mesh stent is still difficult to apply to all types of aortic dissection and aortic aneurysm, especially type A aortic lesions.

[0011] Type A aortic dissection involves the ascending aorta, where the inner diameter of the blood vessel is significantly increased due to the lesion, usually up to 38 to 55 mm. Such a large diameter dense mesh stent cannot be radially compressed to a very small diameter, so a thicker transmission system is often required. This makes it difficult to place the transmission system through the relatively thin femoral artery, especially for Asians with relatively thinner blood vessels, and even makes it impossible to implement. In order to reduce the diameter of the stent in the compressed state, thinner wires can be used to weave the stent, but this results in the radial support force of the stent being insufficient to play a therapeutic role. Summary of the invention

[0012] In view of this, the main purpose of the present invention is to provide a stent that can solve or improve at least one of the above-mentioned prior art problems. Specifically, the purpose of the present invention is to provide a stent for treating aortic dissection or aortic aneurysm, especially type A aortic lesions, with a diameter suitable for delivery through the femoral artery in the delivery state, and the stent can be locally axially compressed in the released state, so as to form a segment with low liquid permeability and high radial support force at the site in need (such as the site of vascular intimal tear), thereby completing the treatment of the lesion site.

[0013] To this end, the present invention provides a bare stent for the aorta, which is formed by overlapping and interweaving at least two first wires and second wires of different diameters. In a naturally released state, the bare stent has a metal coverage of at least 30%, wherein the first wire has a diameter of 20 to 150 μm, and the second wire has a diameter of 150 to 600 μm.

[0014] The bare stent of the present invention is formed by overlapping and interweaving at least two wires of different diameters, namely the first wire and the second wire as defined above. The bare stent woven with the wires within the above range and having the above metal coverage has an appropriate radial support force in the naturally released state (i.e., without axial compression or extension), thereby solving the problem that such stents are difficult to be radially compressed to a delivery configuration of a suitable diameter. Within the range of appropriate radial support force, the stent can be relatively easily radially compressed.

[0015] However, the radial support force of the stent of the present invention is not sufficient to block the intimal tear in the aorta, and the bare stent in the natural release state still has a high fluid permeability. To solve this problem, according to the stent placement method as described in detail below, the bare stent of the present invention is at least partially axially compressible after release. This feature also benefits from the above-mentioned use of two wires of different diameters to form the bare stent of the present invention through overlapping and interweaving. Due to the overlapping weaving method, any wire can move in an orderly manner at the intersection of the wires, which is conducive to the radial compression of the bare stent. When the stent is released in the blood vessel, through local axial compression, a sufficient braid density is obtained in the local section of the non-branched blood vessel of the stent, thereby significantly enhancing the local radial support force and basic liquid-impermeability, and at the same time playing the role of expanding the true lumen of the blood vessel and blocking the tear at the site of the intimal tear.

[0016] The stent of the present invention needs to have an appropriate metal coverage. If the braiding is too dense, it may cause difficulty in radial compression and hinder blood flow; on the contrary, if the braiding is too sparse, even if axial compression is performed, it is difficult to achieve the expected radial support force and liquid-tight performance, and thus the intimal tear site cannot be effectively blocked.

[0017] According to the present invention, when the bare stent is placed in the aorta, it has different compression degrees along its length direction.

[0018] In practical applications, when the bare stent of the present invention is released in the aorta, the metal coverage of different sections of the bare stent may be different depending on the compression ratio, for example, it may vary between the metal coverage at maximum axial compression and the metal coverage in the natural release state.

[0019] Due to the above-mentioned characteristics of the stent of the present invention, the bare stent of the present invention can present different radial supporting forces and fluid permeability in the treatment site according to different requirements, so as to play multiple roles of sealing the rupture of the inner wall of the blood vessel, expanding the true lumen of the blood vessel and maintaining blood delivery to the branch arteries.

[0020] According to one embodiment, in a naturally released state within a blood vessel, the bare stent has a radial supporting force of no less than 200N.

[0021] According to one embodiment, the bare stent of the present invention has a metal coverage rate of 30-60% and a radial support force of 200-600N when in a naturally released state within a blood vessel.

[0022] According to the present invention, when the bare stent is placed in the aorta, it has different compression degrees along its axial direction.

[0023] According to one embodiment, the entire bare stent of the present invention has a uniform braid density. To this end, the first wire and the second wire are interwoven into the bare stent in a uniformly distributed manner.

[0024] According to one embodiment, the bare stent has a metal coverage of not less than 80%, preferably 80-90%, when in a released and axially maximally compressed state.

[0025] According to one embodiment, the stent has a radial supporting force of not less than 400N, preferably 400-1000N, when it is released and in a state of maximum axial compression.

[0026] When the bare stent is compressed to the maximum along the axial direction, the radial support force within the above range can effectively support the narrowed blood vessel lumen. Therefore, in practical applications, when the stent of the present invention is released in a blood vessel (especially the aorta), the radial support force of different sections is actually different according to the compression ratio, and can vary within the range of 200-1000N.

[0027] In the case where the treatment site of the bare stent of the present invention involves the abdominal aorta, the bare stent may be provided with two common iliac artery stent fixing parts for fixing the left and right common iliac artery stents in the internal space. In a specific example, the common iliac artery stent fixing parts are arranged inside the bare stent at the bifurcation of the left and right common iliac arteries corresponding to the abdominal aorta, and the two common iliac artery stent fixing parts are arranged in a tangent ring shape and are formed integrally with the inner wall of the bare stent.

[0028] Different from the fixing parts that form two cylindrical branches at the lower part of the abdominal aorta stent, the two fixing parts of the bare stent of the present invention are arranged inside the bare stent, so that the outer part of the bare stent still maintains a cylindrical shape, which is more conducive to opening the blood vessel without deteriorating the support near the common iliac artery. Moreover, the common iliac artery fixing part is formed integrally with the stent, which can more stably fix the left and right iliac artery stents.

[0029] The bare stent of the present invention can be used in the aorta region from the ascending aorta to the abdominal aorta, including at least the aortic arch and / or the abdominal aorta, or in the aorta region from the ascending aorta to the abdominal aorta, including at least the ascending aorta. To adapt to different application sites, the bare stent of the present invention can have different specifications. Those skilled in the art can choose according to the specific conditions of the patient.

[0030] According to the present invention, the bare stent may have the same diameter as a whole, or the bare stent may have a variable diameter, and the diameter is in the range of 20 to 60 mm, preferably 20 to 55 mm. In general, the stent should have an inner diameter slightly larger than the inner diameter of the blood vessel at the release site after release in order to play a therapeutic role.

[0031] According to one embodiment, the bare stent has a diameter in the range of 20 to 35 mm. For a bare stent, the entire stent may have the same diameter in the above range, or the entire stent may have a diameter that varies in the above range. Such a bare stent is suitable for the aortoiliac vessels from the descending aorta to the abdominal aorta and the iliac arteries on both sides.

[0032] According to another embodiment, a portion of the bare stent has a diameter in the range of 38 to 60 mm, preferably 38 to 55 mm. The bare stent in this embodiment may have a first section located at the proximal end of the bare stent in the released state. The first section may have a diameter of 38 to 55 mm to be suitable for the ascending aorta. The length of the first section after release is 8-11 cm, preferably 8-10 cm. The stent may further have a second section adjacent to the first section. The second section may have a diameter of, for example, 20 to 35 mm to be suitable for the aortic arch, or even extend to a portion of the abdominal aorta. The second section extends to the distal end of the stent following the first section. The length of the second section after release may be 28-40 cm, preferably 28-31 cm. The above two sections may also be formed into two stents respectively, and the second section stent portion extends to the interior of the first section stent when placed. The second method is more flexible. If necessary, three independent stents may also be formed to facilitate operation.

[0033] According to other embodiments, the bare stent may have only a portion corresponding to the descending aorta to the auxiliary aorta, and thus has a diameter of, for example, 20 to 35 mm and a length of 20 to 30 cm.

[0034] The first wire used in the bare stent of the present invention may have a diameter of 50 to 150 μm; and the second wire may have a diameter of 150 to 600 μm.

[0035] According to another embodiment, the bare stent is woven from wires having three different diameters, wherein the first wire may include a first filament and a second filament having different diameters. According to a specific embodiment, the first filament may have a diameter of 20 to 100 μm, and the second filament may have a diameter of 100 to 150 μm.

[0036] According to another embodiment, the bare stent is woven from wires having three different diameters, wherein the second wire 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.

[0037] According to another embodiment, the bare stent is woven from the first and second thin filaments and the first and second thick filaments, four types of filaments with different diameters.

[0038] Of course, more wires with different diameters can be used, but considering the effect and cost, the cost performance of doing so is low.

[0039] The number of wires used to braid the bare stent may be 48 to 156, preferably 48 to 128. The number of second wires may be 4 or more, for example 4 to 32, and the rest are first wires.

[0040] According to one embodiment, the number of wires used to weave the bare stent may be 48 to 156, of which the number of second wires is 4 to 32, and the rest are first wires, which may include 32-120 first filaments and 32-120 second filaments, provided that the total of the first filaments and the second filaments does not exceed 152.

[0041] According to another embodiment, the number of wires used to weave the bare stent may be 48 to 156, wherein the second wires include 6 to 24 first thick wires and 6 to 24 second thick wires, and the rest are first wires, provided that the first thick wires and the second thick wires do not exceed 32.

[0042] Too many thick filaments (i.e., second filaments) will result in the stent being unable to be effectively compressed into an ideal delivery state, while too few will result in the stent being unable to provide the expected radial support force even after compression, and unable to maintain the expected structure and morphology of the stent in the released state. In particular, for the bare stent of the present invention, the number of second thick filaments is preferably no more than 30, preferably no more than 24.

[0043] According to one embodiment, the bare stent is composed of at least two layers of braided mesh. According to one embodiment, the bare stent may have 2 layers, 3 layers or 4 layers of braided mesh, preferably 2 layers. When the bare stent has multiple layers of braided mesh, the stent as a whole has the radial support force and metal coverage specified above.

[0044] It should be understood that according to the radial support force range and metal coverage range required for a specific treatment type, those skilled in the art can select appropriate braiding materials under specific equipment conditions, determine a reasonable number of layers, further select appropriate wire diameters, numbers, etc., and determine an appropriate braiding scheme based on the description herein to obtain a stent with the required radial support force range and metal coverage range. For example, a suitable braiding scheme can be designed using dedicated software.

[0045] According to a further embodiment, the end of the bare stent of the present invention (especially the proximal end, where the radial support force of the stent is the largest) can be formed by a back-weaving method. For the other end, if there is a burr that cannot be back-weaved again, the burr can be located on the inner side of the bare stent by selecting a suitable arrangement of each layer; or if there are two layers of burrs, one layer of burrs can be back-weaved a short distance and the other burr can be wrapped in the back-weaving section, or when multiple stents are used in combination, a single layer or two layers of burrs can be overlapped and placed in another dense mesh stent. The bare stent of this embodiment has a smooth end, thereby avoiding mechanical damage to the inner wall of the blood vessel by the exposed wire end (burr).

[0046] The bare stent of the present invention is self-expandable or capsule-expandable. The materials of the first wire and the second wire of the bare stent can be different, but preferably the same. Usually the material of the wire can be metal, such as shape memory alloy (such as Nitinol), cobalt-chromium alloy, tungsten or tantalum.

[0047] The bare stent of the present invention can be delivered through the femoral artery using a delivery system with a conventional outer diameter (such as about 5 to about 10 mm, preferably about 5 to about 7 mm), without using a delivery system with a larger outer diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of a bracket according to the present invention and a partially enlarged schematic diagram;

[0049] Figure 2 A schematic diagram of a stent according to the present invention partially undergoing axial compression and stretching;

[0050] Figure 3 A schematic diagram of a bare stent according to another embodiment of the present invention;

[0051] Figure 4 A schematic diagram of a partial enlargement of a stent according to an embodiment of the present invention;

[0052] Figure 5 is a schematic cross-sectional view of a multi-layer stent wall according to the present invention;

[0053] Figure 6 is a schematic diagram of a stent delivery system according to the present invention; and

[0054] Figure 7 It is a schematic diagram of placing a stent at an aortic intimal rupture using the stent delivery system of the present invention. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. In the absence of conflict, the technical solutions recorded in the embodiments of the present invention can be implemented in any combination. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0057] The same reference numerals in the drawings refer to the same components. The shapes and sizes of the components in the schematic drawings are for illustration only and should not be considered to reflect the actual shapes, sizes and absolute positions.

[0058] It should be noted that, in the present invention, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a method or apparatus including a series of elements includes not only the elements explicitly stated, but also includes other elements not explicitly listed, or also includes elements inherent to the implementation of the method or apparatus.

[0059] It should be noted that the terms "first\second" involved in the present invention are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that "first\second" can be interchanged with a specific order or sequence where permitted. It should be understood that the objects distinguished by "first\second" can be interchanged where appropriate, so that the embodiments and examples of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0060] In order to describe the present invention more clearly, the terms "proximal end" and "distal end" are commonly used in the field of interventional medicine, wherein the "distal end" refers to the end away from the heart during the surgical operation, and the "proximal end" refers to the end close to the heart during the surgical operation.

[0061] As used herein, the terms "bare stent" and "stent", unless otherwise specified, are used interchangeably and have the same meaning, i.e., referring to a bare stent.

[0062] The present invention provides a bare stent for use in the aorta, wherein the bare stent is woven from a first wire and a second wire having at least two different diameters, and the stent is constructed to be at least partially compressible along the axial direction of the stent in a released state.

[0063] Figure 1 The schematic diagram and the partially enlarged schematic diagram of the stent 1 according to the present invention are shown. The stent 1 is formed by overlapping and weaving a plurality of first wires 3 and a plurality of second wires 4. Figure 1 The stent 1 shown is a single-layer mesh structure having meshes 5 .

[0064] The stent of the present invention may also have a multi-layer structure, for example, 2 to 4 layers. For example, the multi-layer structure may be formed by back-weaving.

[0065] The stent of the present invention is suitable for use in any segment from the ascending aorta to the abdominal aorta or in the entire aorta, and thus may have a large diameter ranging from about 60 mm (preferably 55 mm) to about 20 mm.

[0066] According to the present invention, the stent 1 can be woven with a total of 48 to 156, preferably 48 to 128 wires. For example, the stent of the present invention can be woven with 48, 64, 96, or 128 wires. The number of wires can be determined according to the diameter of the stent, the number of layers, and the material of the wires used.

[0067] The material used for the stent of the present invention can be any suitable material used for peripheral vascular stents, as long as the material can provide sufficient radial support and has a certain fineness. Usually, metal wires are preferably used, such as nickel-titanium alloy wires, cobalt-chromium alloy wires, tungsten wires, tantalum wires, etc., and nickel-titanium alloy wires are more preferably used.

[0068] The second wires 4 as thick wires are at least 4, usually not more than 32. The diameter of the second wire 4 is between 150 and 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 basic support and complete structure for the stent 1. However, the number of second wires cannot be too much. For example, even if only 300 μm diameter wires are used, when it reaches about 32, especially for the ultra-large diameter stent part greater than about 40 mm, it is difficult to compress it to a suitable delivery size, resulting in it being unusable.

[0069] In the stent 1, except for the thick wire, the rest are the first wire 3 as thin wires. The first wire 3 used in the present invention can have a diameter of 20 to 150 μm, preferably 50 to 150 μm, for example: 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 1120 μm, 130 μm, 140 μm and 150 μm. The first wire 3 plays the role of auxiliary support for the stent 1 and fills the gap of the second wire 4. And the first wire 3, because the number is much larger than the second wire 4, also plays the role of maintaining the shape of the stent 1. The inventors found that although it seems feasible in theory, in fact, using the overlapping braiding method of the present invention, a large-diameter stent with a certain shape and sufficient supporting force cannot be formed by the second wire (i.e., thick wire) alone. And the large-diameter stent fixed by the intersection of the wire and the wire formed by, for example, laser engraving technology, even if the diameter of the wire is the same, the supporting force is much smaller, and it cannot meet the requirements of the present invention for aortic blood vessels.

[0070] The stent 1 of the present invention is interwoven by overlapping, and the intersections between the filaments can generate free relative movement, so any mesh 5 on the stent 1 of the present invention can be easily compressed. The stent 1 formed in this way can be axially compressed along its central axis AA to form a compressed stent 1' or radially compressed along the direction DD to the central axis of the stent to form a compressed stent 1" (see Figure 2 ).

[0071] The "interweaving" mentioned in this article refers to the first wire and the second wire being woven together from one end of the stent to the other end, so as to distinguish it from the weaving method of those stents including multiple segments, one segment of which is woven with wires of one diameter and the other segment is woven with wires of another diameter.

[0072] The "axial direction" of the stent mentioned in this article refers to Figure 2 The direction along AA shown is the direction of the central axis of the cylindrical shape of the stent. The "radial direction" of the stent mentioned in this article refers to the direction along the AA direction. Figure 1 The direction shown is along DD, which is the diameter direction of the circle of the cylindrical shape of the stent. Generally, "compression along the radial direction" herein refers to compression from the circumference to the center of the circle.

[0073] The above characteristics of the stent of the present invention can bring various benefits. Since the stent can be axially compressed, the compressed stent forms a high radial support force and a high braid coverage. The high radial support force can achieve effective expansion of the narrowed part of the blood vessel, while the high braid coverage can achieve very low fluid permeability, effectively blocking the damaged part of the vascular endothelium. At this time, the second wire 4 in the stent 1 plays the role of supporting the skeleton, and the first wire fills the gap between the second wires, playing a role similar to the fabric membrane of the coated stent. Unlike the coated stent, the bare stent of the present invention can provide a relatively high radial support force after axial compression, and can even be effectively used in the treatment of type A aortic dissection involving the ascending aorta.

[0074] The stent 1 of the present invention can have a radial supporting force of not less than 200N in a naturally released state; and can have a radial supporting force of not less than 400N in a state of maximum axial compression.

[0075] The "natural release state" of the stent mentioned herein refers to the state in which the stent is not axially compressed and released when fixed in a 37±2°C water bath.

[0076] The "maximum axial compression state" of the stent mentioned herein refers to a state in which the stent is axially compressed to the point where it cannot be further compressed when in a naturally released state.

[0077] The "radial support force" of the stent mentioned in this article refers to the force required to compress the stent to 85% of its original diameter along the diameter direction after the stent is fixed in the natural release state.

[0078] In contrast to the radial support force, the stent of the present invention also needs a high degree of liquid impermeability in order to effectively block the rupture of the vascular intima. This property can be represented by the metal coverage. The stent 1 of the present invention can have a metal coverage of 30-60% in the natural release state; and can have a metal coverage of not less than 80% in the axial maximum compression state.

[0079] The "metal coverage" of the stent mentioned in this article refers to the metal coverage ratio per unit area measured by electron microscope scanning. The sum of the metal coverage and void ratio per unit area should be 100%.

[0080] Figure 3 A modified embodiment of the present invention is shown. According to this embodiment, the bare stent of the present invention may have two iliac artery stent fixing parts for receiving and fixing the left and right iliac artery stents in the portion corresponding to the treatment site of the abdominal aorta. Figure 3 , in which a bare stent of this embodiment is schematically shown. Figure 3 The stent 20 shown is suitable for use in the abdominal aorta segment. The interior of the lower portion of the stent 20 has a common iliac artery stent fixing portion 22 arranged as two adjacent annular channels. For clarity, Figure 3 The fixing portion 22 is shown as a plane in the figure, but in fact the fixing portion 22 has a certain thickness. In some examples, the fixing portion 22 of the common iliac artery stent may extend downward to the lower end of the stent 20.

[0081] The common iliac artery stent fixing portion 22 is also woven from the same first and second wires as the stent 20 (the first and second wires are not shown), and is formed integrally with the bare stent. The two annular outer portions are integrally woven with the inner wall of the stent 20. The inner diameters of the two circular channels are adapted to the outer diameters of the left and right common iliac artery stents to be received and fixed, and are usually slightly smaller than the outer diameters of the left and right common iliac artery stents, so as to be able to fix the common iliac artery stents.

[0082] According to one embodiment, the stent of the present invention can be woven from three wires having different diameters. Figure 4 As shown, a partially enlarged schematic diagram of a single layer of the stent of this embodiment is shown. The stent is woven from two first wires 33a, 33b and a second wire 34. The first wire includes a first filament 33a, which may have a diameter of 50 to 100 μm, and a second filament, which may have a diameter of 100 to 150 μm; the second wire may have a diameter of 150 to 600 μm, preferably a diameter of 150 to 400 μm. This embodiment may also have other variations, such as having a first wire and two second wires (for example, with diameters in the range of 150 to 300 μm and 300 to 600 μm, respectively), or a stent composed of two first wires and two second wires (not shown), but is not limited thereto.

[0083] The radial supporting force of a stent formed by three or more wires of different diameters is more uniform throughout the stent, and the flexibility of the stent may also be enhanced.

[0084] As described above, the stent of the present invention may have multiple layers, preferably double layers, three layers or four layers. According to a preferred embodiment, the multi-layer stent may be formed by back-weaving a single-layer woven mesh. Figure 5 As shown in A to C, a cross-sectional schematic diagram of 2 to 4 layers of the support wall is shown. Figure 5 A is a double-layer structure, in which the upper layer 42 of the structure is located on the inner side of the stent, and the lower layer 44 is located on the outer side of the stent (i.e., the side in contact with the blood vessel wall). In this structure, the proximal end 41 is braided back to form a smooth port. At the distal end 43, the lower layer 44 facing the outside of the stent is braided back for a distance, and the open edge (burr) of the distal end of the upper layer 42 facing the inside of the stent is wrapped inside the lower layer 44. Thus, a port with smooth ends is formed. Similarly, Figure 5 In the B, the upper layer 52 is woven back at the proximal end 51 to form the lower layer 54, and further woven back at the distal end 53 to form the middle layer 56. The lower layer 54 and the middle layer 56 at the distal end 53 are slightly longer than the upper layer 52, so that the open edge of the distal end of the upper layer is located inside the stent. In this way, both ends of the stent are smooth ports. Figure 5 The same is true for the four layers in C. The two layers 62 and 68 on the inner side of the stent are shorter than the edges formed by the two layers 64 and 66 on the outer side of the stent at the distal end 63, while the proximal end 61 forms the bottom layer 64 by weaving the top layer 62 back to wrap the two middle layers 68 and 66 in the middle. A modified method can be to weave a small section back at the distal end of the top layer 62 or the middle layer 68 to wrap the open edge of another layer in the middle. In this way, both ends of the stent are completely smooth ports.

[0085] The stent of the present invention is preferably in a multi-layered form, so that both ends (especially the proximal end) of the stent can form smooth ports to prevent the open edges of the braid from causing secondary damage to the blood vessels.

[0086] The above is a detailed description of the stent of the present invention by way of examples. Those skilled in the art should understand that the above examples are used to illustrate the advantages of the stent of the present invention rather than to limit the scope of the present invention, and the features in the examples can be applied to the stents of other examples individually or in combination under appropriate circumstances. Obvious deformations and modifications made to the stent by those skilled in the art based on the disclosure herein are also within the scope of the present invention as long as they conform to the concept of the present invention.

[0087] The stent of the present invention can be placed in the corresponding blood vessel part through the stent delivery system. The delivery system that can be used to deliver the stent of the present invention has an outer diameter for placing a conventional aortic stent, such as 5 to 10 cm, preferably 5 to 7 cm. The stent of the present invention as described above is assembled in the system in a delivery configuration, and both ends of the stent are restrained, and the restraint is removed only when the other parts of the stent are completely released, so that the stent is completely released.

[0088] refer to Figure 6, which shows a schematic diagram of a stent delivery system 100 according to the present invention. The delivery catheter 120 for stent delivery comprises an outer catheter 130, an inner catheter 140 and a push rod 170 which are coaxially arranged in sequence from outside to inside along the longitudinal axis XX. The delivery catheter 120 has a distal end 123 and a proximal end 122. The delivery catheter 120 also has a hemostatic valve 125. The outer catheter 130 has a proximal end 180 and a distal end 190, and a first hollow cavity 133 runs through the entire outer catheter 130. The inner catheter 140 is coaxially arranged with the outer catheter 130 along the longitudinal axis XX in the first hollow cavity 133 of its distal end 190, and has a second hollow cavity 143. The push rod 170 extends through the first hollow cavity 133 of the outer catheter 130 and through the second hollow cavity 143 of the inner catheter 140 to the outside of the distal end port 135 of the outer catheter. The push rod 170 may have a third hollow cavity (not shown) for the guide wire to pass therethrough.

[0089] In the proximal end 180 of the outer catheter 130, the stent 150 is releasably held in the first hollow cavity 133 between the push rod 170 and the outer catheter 130 in a delivery configuration. The first restraint 161 restrains the proximal end 154 of the stent 150 at the proximal end of the push rod 170. The first restraint 161 can be a conventional stopper, which can be removed from the stent 150 when necessary, so that the proximal end 154 of the stent 150 is released. The second restraint 162 restrains the distal end 156 of the stent 150 at the proximal end of the inner catheter 140. Similarly, the second restraint 162 can be a conventional stopper, which can be removed from the stent 150 when necessary, so that the distal end 156 of the stent 150 is released.

[0090] According to the delivery system 100 of this embodiment, the proximal end 131 of the outer catheter 130 can be separated from the proximal end 122 of the delivery catheter 120. By pushing the push rod 170 toward the proximal end or by pulling the outer catheter 130 toward the distal end, the outer catheter 130, the inner catheter 140 and the push rod 170 can be moved relative to each other.

[0091] Figure 6 The system 100 shown in the figure pushes the push rod 170 toward the proximal end 122, so that the proximal end 122 of the delivery catheter 120 drives the push rod 170 fixedly connected thereto, the stent 150 bound together with the end of the push rod 170, and the inner catheter bound together with the distal end of the stent to move toward the proximal end relative to the outer catheter 130. In this way, the stent 150 begins to be released from its proximal end 154.

[0092] Combination Figure 7 , which shows a schematic diagram of placing a stent at an aortic intimal rupture using the stent delivery system of the present invention. Figure 7A of FIG. 1 shows a section of an aorta 91 including a rupture 93 in the intima of the blood vessel, which causes a tear in the intima to form a false lumen 92. The stent delivery system 100 of the present invention has been guided to the rupture 93, and while keeping the position of the outer catheter 130 unchanged, a section of the stent 151 has been released by pushing the push rod in the direction indicated by the arrow. Figure 7 B, keep the inner and outer catheters of the delivery system 100 unchanged, pull the push rod back in the direction of the arrow in the figure, so that the released stent segment 151 is compressed back and finally abuts against the blood vessel area where the rupture 93 of the vascular endothelium is located, forming a compressed segment 151'. When designing a stent, the diameter of the stent is usually designed to be slightly larger than the diameter of the blood vessel at the placement site, so that the compressed segment 151' tightly abuts against the inner wall of the segment of the blood vessel, blocks the rupture 93, and expands the true lumen of the segment of the blood vessel. Due to the inward contraction force of the blood vessel wall, the compressed segment 151' is maintained in the segment of the blood vessel in the compressed shape.

[0093] then, Figure 7 As shown in C, the outer catheter 130 is pulled toward the distal end in the direction indicated by the arrow in the figure (the inner catheter 140 and the push rod 170 remain stationary) to further release the remaining stent segments 152. Finally, when the stent 150 is completely released, the restraints on both ends of the stent by the stopper are removed, so that the entire stent 150 is released to the treatment site, and the delivery catheter is withdrawn from the blood vessel (see Figure 7 D). The stent 150 placed at the lesion site has two sections, one is a compression section 151', and the other is a natural release section 152. The compression section 151' has a blocking effect on the breach 93 and a strong radial support effect on the blood vessel, and the natural release section 152 has a proper support effect on other parts of the blood vessel and does not hinder the flow of blood, especially does not hinder the flow of blood to the branch blood vessels.

[0094] According to the present invention, after the stent segment 151 is released (ie, Figure 7 The position of the stent can be confirmed when the stent is in the state shown in A, so that the compressed section can accurately block the breach 93. If the position is not ideal, it can be adjusted, or even the released section 151 can be retracted into the outer catheter again, and the position of the delivery system can be adjusted before it is released again.

[0095] Similarly, the position of the stent can be confirmed after any section is released to obtain the best placement effect. Finally, before removing the restraints on both ends of the stent, the position of the stent is confirmed again, because at this time, if the placement position is found to be unsatisfactory, the stent can be recovered and released again. When the restraints on both ends of the stent are removed, the position of the stent can no longer be adjusted.

[0096] In addition, the compression patterns of other sections of the stent are similar to Figure 7 Similar to that shown in B. For example, after the front part of the stent is released and has already abutted against the vessel wall, a section of the stent is continuously released. Since the end of the subsequently released stent is bounded by the outer catheter, the outer catheter and the inner catheter can be simultaneously moved toward the proximal end by keeping the push rod stationary, so that a section of the stent that is newly released but has not yet abutted against the vessel wall is compressed and abuts against the vessel wall, forming a section with high metal coverage and high radial support force.

[0097] The above examples illustrate the detailed scheme of the stent delivery system of the present invention and the method of placing the stent in a blood vessel using the system. Those skilled in the art can easily make deformations and modifications based on the above content to adapt to actual application needs without departing from the spirit of the present invention, and these deformations and modifications are also within the scope of the present invention.

[0098] Example

[0099] This embodiment provides a similar Figure 1 The bare stent of the structure shown is used in the descending aorta area. The bare stent is made of nickel-titanium alloy material and is interwoven with 54 first wires with a diameter of 100 μm and 12 second wires with a diameter of 400 μm. The bare stent is woven in two layers in a back-weaving manner. The back-weaving manner is as follows Figure 5 As shown in A, the proximal end is a smooth end that is braided back, and the distal end is a two-layer hair. The outer rough edge is braided back into a small section and the inner rough edge is placed inside the braided section to prevent the rough edge from being exposed and damaging the blood vessel wall.

[0100] The bare stent is conical, with a proximal diameter of 45 mm, a distal diameter of 32 mm, and a length of 8 cm. The stent can be fixed in a blood vessel for up to 24 cm after being released.

[0101] Scanning electron microscope detection shows that the metal coverage of the stent in this embodiment is 40% in the natural state, and the metal coverage is about 90% after the maximum axial compression. Detected by a radial support force tester, the radial support force of the thicker part of the stent in this embodiment in the natural state is 350N, and the radial support force of each part after the maximum axial compression is greater than 400N, or even greater than 600N.

[0102] In addition, in order to simulate the axial bending stress of the stent when it is fixed at the aortic arch, the radial recoil force of the stent was measured to be 0.4 to 1.0N.

[0103] The above descriptions are only some specific embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An axially compressible bare stent, the bare stent is used for the aorta, characterized in that: The bare stent has at least two layers of woven mesh formed in a back-woven manner, and the bare stent is formed by overlapping and interweaving at least two first wires and second wires of different diameters, wherein the first wire has a diameter of 20 μm to 150 μm, and the second wire has a diameter of 150 μm to 600 μm; The bare stent has a metal coverage of 30%-60% and a radial support force of 200N-600N in a naturally released state; The bare stent has a metal coverage of 80%-90% when it is released and in a state of maximum axial compression; When the bare stent is released and in a state of maximum axial compression, it has a radial supporting force of 400N-1000N.

2. The bare stent according to claim 1, characterized in that: When the bare stent is placed in the aorta, it has different compression degrees along its axial direction.

3. The bare stent according to claim 1, characterized in that: The first wire and the second wire are interwoven into the bare stent in a uniformly distributed manner.

4. The bare stent according to claim 1, characterized in that: The bare stent is used in a region including the abdominal aorta, and the bare stent is provided with two common iliac artery stent fixing parts in the internal space for fixing left and right common iliac artery stents.

5. The bare stent according to claim 4, characterized in that: The common iliac artery stent fixing portion is arranged inside the bare stent at the bifurcation of the left and right common iliac arteries corresponding to the abdominal aorta, and the two common iliac artery stent fixing portions are arranged in tangent rings and are formed integrally with the inner wall of the bare stent.

6. The bare stent according to claim 1, characterized in that: The bare stent has the same diameter as a whole, or the bare stent has a varying diameter, and the diameter is within the range of 20 mm to 60 mm.

7. The bare stent according to claim 6, characterized in that: The bare stent has a diameter in the range of 20 mm to 35 mm, or a portion of the bare stent has a diameter in the range of 38 mm to 60 mm.

8. The bare stent according to claim 1, characterized in that: The first filament includes a first filament and a second filament having different diameters, wherein the first filament has a diameter of 20 μm to 100 μm, and the second filament has a diameter of 100 μm to 150 μm.

9. The bare stent according to claim 1, characterized in that: The second filaments include a first thick filament and a second thick filament having different diameters, wherein the first thick filament has a diameter of 150 μm to 300 μm, and the second thick filament has a diameter of 300 μm to 600 μm.

10. The bare stent according to claim 1, characterized in that: The bare stent is woven from 48 to 156 wires, wherein the second wires are 4 to 32 and the rest are first wires.

11. The bare stent according to claim 8, characterized in that: The bare stent is woven from 48 to 156 wires, wherein the second wires are 4 to 32 and the rest are first wires. When the total of the first filaments and the second filaments does not exceed 152, the first filaments include 32 to 120 first filaments and 32 to 120 second filaments.

12. The bare stent according to claim 9, characterized in that: The bare stent is woven from 48 to 128 wires. When the first thick wires and the second thick wires do not exceed 32, the second wires include 6 to 24 first thick wires and 6 to 24 second thick wires, and the rest are first wires.

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