Vascular stent of axial zero poisson's ratio structure

Abstract

The application provides a vascular stent with an axial zero Poisson's ratio structure, comprising a plurality of circular ring-shaped support bodies; the circular ring-shaped support body comprises a plurality of circular ring-shaped support units, the circular ring-shaped support units are arranged in a circumferential direction, and adjacent circular ring-shaped support units are connected through connecting units; the plurality of circular ring-shaped support bodies are arranged in an axial direction, and adjacent circular ring-shaped support bodies are connected through connecting ribs; and the circular ring-shaped support units are uniformly provided with circular small holes for loading drugs or fixing a developing agent. The application can realize an almost zero axial shortening rate, keep the axial length of the stent almost unchanged during the crimping and expansion of the vascular stent, and improve the positioning accuracy during the implantation of the vascular stent.

Description

Technical Field

[0001] This invention belongs to the field of interventional medical device technology, specifically relating to a vascular stent with an axial zero Poisson's ratio structure. Background Technology

[0002] Atherosclerosis is a major cause of coronary heart disease, cerebral infarction, and peripheral vascular disease. Lipid metabolism disorders form the pathological basis of atherosclerosis, characterized by lesions starting in the intima of affected arteries. This typically begins with the accumulation of lipids and complex carbohydrates, hemorrhage, and thrombosis, followed by fibrosis and calcification, and gradual degeneration and calcification of the arterial media, leading to thickening and hardening of the arterial wall and narrowing of the lumen. The lesions commonly affect large and medium-sized muscular arteries; once they progress to the point of obstructing the arterial lumen, the tissues or organs supplied by that artery will experience ischemia or necrosis. Because the lipids accumulated in the arterial intima appear as a yellowish, porridge-like substance, it is called atherosclerosis.

[0003] The basic pathological change is the formation of plaques on the arterial intima, including lipid streaks, fibrous plaques, and atherosclerotic plaques. Further progression of the disease can lead to secondary complications such as calcification, atherosclerotic ulceration, thrombosis, and intraplaque hemorrhage. The latter two types of secondary complications, in particular, are prone to causing adverse consequences. The disease easily affects large elastic arteries, such as the aorta and its first-order branches, and medium-sized muscular arteries, such as the coronary arteries, cerebral arteries, renal arteries, and large branches of limb arteries. Narrowing or even occlusion of muscular arteries, in particular, can cause ischemic changes in tissues or organs. Myocardial infarction caused by coronary atherosclerosis and cerebral infarction caused by cerebral atherosclerosis pose the greatest threat to human health and are the leading causes of death from cardiovascular diseases. The nature of atherosclerotic lesions is now considered to be an excessive reaction following damage to the endothelial cells and smooth muscle cells of the arterial wall, similar in nature to inflammation.

[0004] The symptoms of atherosclerosis mainly depend on the degree of ischemia in the vascular lesions and affected organs. Aortic atherosclerosis often has no specific symptoms; coronary atherosclerosis, if the diameter is narrowed by more than 75%, can cause angina pectoris, myocardial infarction, arrhythmia, and even sudden death; cerebral arteriosclerosis can cause cerebral ischemia, cerebral atrophy, or cerebral hemorrhage due to rupture of cerebral blood vessels; renal artery atherosclerosis often causes nocturia, refractory hypertension, and in severe cases, renal insufficiency; mesenteric artery atherosclerosis can manifest as abdominal pain after meals, indigestion, constipation, etc., and in severe cases, intestinal wall necrosis can cause symptoms such as hematochezia and paralytic ileus; lower extremity arteriosclerosis causing severe stenosis of the vascular lumen can cause intermittent claudication, disappearance of dorsalis pedis pulse, and in severe cases, even gangrene.

[0005] Risk factors for coronary heart disease (CHD) include modifiable and unmodifiable risk factors. Understanding and intervening in these risk factors is helpful in the prevention and treatment of CHD. Modifiable risk factors include: hypertension, dyslipidemia (high total cholesterol or high LDL cholesterol, high triglycerides, low HDL cholesterol), overweight / obesity, hyperglycemia / diabetes, unhealthy lifestyle habits including smoking, unhealthy diet (high fat, high cholesterol, high calories, etc.), lack of physical activity, excessive alcohol consumption, and psychosocial factors. Unmodifiable risk factors include: gender, age, and family history. In addition, infections such as cytomegalovirus, Chlamydia pneumoniae, and Helicobacter pylori can also contribute. CHD attacks are often associated with seasonal changes, emotional stress, increased physical activity, overeating, heavy smoking, and alcohol consumption.

[0006] Currently, there are three main treatment methods for vascular stenosis: medication, bypass surgery, and stent placement. Medication is suitable for mild to moderate stenosis and typically involves drugs with lipid-lowering and antiplatelet functions. Its characteristics include low cost, limited effectiveness, slow onset of action, and a long treatment period, only reducing the incidence of cardiovascular disease to a certain extent. Bypass surgery involves taking a section of the patient's own blood vessel and suturing it to both ends of the stenotic vessel, bypassing the narrowing to restore blood flow. Bypass surgery is an open procedure with high risks and significant trauma; the procedure can easily cause hidden damage to surrounding tissues and blood vessels, and the recovery period is long. Generally used for patients with complex conditions, interventional treatment involves using a catheter to deliver a vascular stent. The catheter is routed through a curved section of the blood vessel to the target site. After angiography confirms the location, pressure is applied to inflate the stent with a balloon. The stent, due to plastic deformation, supports the narrowed area of ​​the blood vessel. The first interventional treatment was performed in 1977 by German physician Gruentzig, who inserted a pre-coiled balloon into the body using a guidewire. Pressure was applied to the balloon at the site of the vascular lesion, dilating the narrowed vessel and successfully restoring blood flow. Since then, balloon angioplasty has been widely used globally for the treatment of cardiovascular diseases. However, later clinical data showed that due to the elasticity of the blood vessel itself and the compression from surrounding tissues, the narrowed vessel gradually elastically recoils, causing the stent to shorten axially, resulting in a restenosis rate as high as 30%-50%. Therefore, this method has gradually been replaced by vascular stent implantation.

[0007] Poisson's ratio is the ratio of the transverse normal strain to the axial normal strain of a material under uniaxial tension or compression. Also called the transverse deformation coefficient, it is an elastic constant reflecting the transverse deformation of the material. The concept of Poisson's ratio was first discovered and proposed by the French scientist Poisson, who defined it as the ratio of transverse strain to longitudinal strain under uniaxial tension or compression. Most engineering materials experience cross-sectional contraction under uniaxial tension, resulting in negative transverse strain and a positive Poisson's ratio. However, some materials maintain a constant cross-section under uniaxial tension, resulting in a zero Poisson's ratio. A Poisson's ratio of 0 means that the absolute value of the transverse normal strain to the axial normal strain under uniaxial tension or compression is zero; it is also called a transverse deformation coefficient of 0.

[0008] In most cases, interventional therapy is the optimal approach. The treatment outcome of stent placement is largely related to the structural performance parameters of the vascular stent, one crucial aspect being the axial shortening rate. Typically, after radial expansion, the stent shortens axially, affecting the positioning accuracy during implantation. This makes it difficult to completely cover the lesion and increases the risk of in-stent damage to the vascular intima due to stent shortening, potentially inducing restenosis. In other words, axial shortening occurs after radial expansion, meaning the stent length contracts as it expands. Therefore, clinicians must choose a stent longer than the occlusion site. However, the degree of radial expansion and the final stent length after expansion vary from person to person. Thus, stent length selection relies on the physician's experience and judgment, which can lead to errors and stent misalignment. More seriously, excessive stent shortening can cause friction between the stent tip and the vessel wall, resulting in endothelial damage and further inducing in-stent restenosis. Summary of the Invention

[0009] To address the problems existing in the prior art, one objective of this invention is to provide a vascular stent with an axial zero Poisson's ratio structure, comprising several annular supports and connecting ribs. Each annular support comprises several annular support units, which are arranged circumferentially along the stent. Adjacent annular support units are connected by S-shaped connecting units to form an annular support body. This invention can achieve almost zero axial length change, ensuring that the axial length of the stent remains almost constant during the compression and expansion of the vascular stent. The overall structure exhibits a zero Poisson's ratio effect, improving the positioning accuracy during vascular stent implantation.

[0010] One objective of this invention is to provide a circular support unit with uniformly distributed small circular holes for loading drugs or fixing contrast agents. CT angiography (CTA) combines CT enhancement technology with thin-slice, large-area, and rapid scanning techniques, and through proper post-processing, clearly displays the details of blood vessels throughout the body. It is non-invasive and easy to operate, and is of great value for vascular variations, vascular diseases, and displaying the relationship between lesions and blood vessels. Contrast agents allow for clearer observation of the relationship between the vascular stent and the lesion location during CT angiography. Loaded drugs, such as flunarizine, rapamycin, or paclitaxel, can effectively inhibit intimal hyperplasia, promote blood circulation, and treat some cardiovascular and cerebrovascular diseases. The near-zero axial length variation improves the positioning accuracy during implantation, completely covers the lesion location, reduces stent damage to vascular tissue, and lowers the probability of in-stent restenosis.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A vascular stent with an axial zero Poisson's ratio structure includes several annular supports;

[0013] The annular support body includes several annular support units, which are arranged circumferentially, and adjacent annular support units are connected by connecting units.

[0014] Several annular supports are arranged along the axial direction, and adjacent annular supports are connected by connecting ribs.

[0015] The annular support unit has evenly distributed circular holes for loading drugs or fixing contrast agents.

[0016] In the above scheme, two adjacent annular support units are connected by an S-shaped connecting unit.

[0017] Furthermore, the length L1 from the crest to the trough of the S-shaped connecting unit is between twice the outer radius R1 and twice the inner radius R2 of the annulus, satisfying the following relationship:

[0018] 2R2 <L1<2R1。

[0019] In the above scheme, the radius R3 of the circular hole should satisfy the following relationship with the outer radius R1 and the inner radius R2 of the annulus:

[0020]

[0021] In the above scheme, the first and last annular support units of the annular support body are connected by a connecting unit to form a ring structure.

[0022] In the above scheme, the S-shaped connecting ribs between the axially arranged annular supports are staggered.

[0023] In the above scheme, the vascular stent is made by laser engraving using medical 316L stainless steel microtubes, L605 cobalt-chromium alloy microtubes, shape memory alloy microtubes, or biodegradable magnesium alloy microtubes.

[0024] In the above scheme, the number of the annular support bodies is determined according to the length of the bracket.

[0025] The drugs listed in the above protocol are flunarizine, rapamycin, or paclitaxel.

[0026] In the above scheme, the number and radius of the circular holes are determined according to the required metal coverage and drug loading or the amount of fixative developer.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides a vascular stent with almost zero axial length change during compression and expansion, formed by the annular support and S-shaped connecting ribs. The axial length of the stent remains almost constant during compression and expansion, exhibiting a zero Poisson's ratio effect. This improves the positioning accuracy during stent implantation. Furthermore, since the stent experiences almost no axial length change during expansion, it reduces frictional damage to the vascular endothelial tissue, thereby lowering the probability of in-stent restenosis.

[0029] This invention features a circular support unit with evenly distributed small circular holes for loading drugs or fixing contrast agents. CT angiography (CTA) combines CT enhancement technology with thin-slice, large-area, and rapid scanning techniques. Through proper post-processing, it clearly displays the details of blood vessels throughout the body. It is non-invasive and easy to operate, and is of great value for vascular variations, vascular diseases, and displaying the relationship between lesions and blood vessels. Contrast agents allow for clearer observation of the relationship between vascular stents and lesion locations during CT angiography. The loaded drugs, such as flunarizine, rapamycin, or paclitaxel, can effectively inhibit intimal hyperplasia, promote blood circulation, and treat some cardiovascular and cerebrovascular diseases.

[0030] The S-shaped connecting ribs of this invention can provide better flexibility, making it easier to deliver the stent to the lesion site and better conform to the lesion site of the tortuous blood vessel; while the support body composed of a circular structure can provide higher radial support force after the stent expands; thus taking into account the two important mechanical properties of stent flexibility and support, it has better overall performance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the circumferentially unfolded planar structure of a vascular stent according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of a single annular support of a vascular stent according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the annular support unit of a vascular stent according to an embodiment of the present invention.

[0034] Figure 4 This is a front view schematic diagram of the overall structure of a vascular stent according to an embodiment of the present invention.

[0035] Figure 5 This is a three-dimensional schematic diagram of the overall structure of a vascular stent according to an embodiment of the present invention.

[0036] Figure 6 This is a simulation diagram of ABAQUS vascular stent expansion according to one embodiment of the present invention.

[0037] In the diagram: 1 - First circular support; 2 - Second circular support; 3 - Third circular support; 4 - Fourth circular support; 5 - Fifth circular support; 6 - Sixth circular support; 7 - Seventh circular support; 8 - Eighth circular support; 11 - First group of S-shaped connecting ribs; 12 - Second group of S-shaped connecting ribs; 13 - Third group of S-shaped connecting ribs; 14 - Fourth group of S-shaped connecting ribs; 15 - Fifth group of S-shaped connecting ribs; 16 - Sixth group of S-shaped connecting ribs; 17 - Seventh group of S-shaped connecting ribs; R1 - Circular support. R2 - Outer radius of the support unit; R3 - Inner radius of the annular support unit; L1 - Radial length from crest to trough of the S-shaped connecting unit; 21 - First annular support unit; 22 - First S-shaped connecting unit; 23 - Second annular support unit; 24 - Second S-shaped connecting unit; 25 - Third annular support unit; 26 - Third S-shaped connecting unit; 27 - Fourth annular support unit; 28 - Fourth S-shaped connecting unit; 29 - Fifth annular support unit; 30 - Fifth S-shaped connecting unit; 31 - Sixth annular support unit; 32 - Sixth S-shaped connecting unit. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "front," "rear," "left," "right," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] Figure 1-5 The image shows a preferred embodiment of a vascular stent with an axial zero Poisson's ratio structure according to the present invention. The vascular stent, whose axial length changes almost zero during compression and expansion, includes several annular supports.

[0042] The annular support body includes several annular support units, which are arranged circumferentially, and adjacent annular support units are connected by connecting units.

[0043] Several circular supports are arranged circumferentially, and adjacent circular supports are connected by connecting ribs.

[0044] The annular support unit has evenly distributed circular holes for loading drugs or fixing contrast agents.

[0045] The annular support unit mainly provides radial support for the vascular stent, while the S-shaped connecting unit mainly provides circumferential and axial connection.

[0046] According to this embodiment, preferably, two adjacent annular support units are connected by an S-shaped connecting unit.

[0047] According to this embodiment, preferably, the length L1 from the crest to the trough of the S-shaped connecting unit is between twice the outer radius R1 of the annulus and twice the inner radius R2 of the annulus, that is, it satisfies the following relationship:

[0048] 2R2 <L1<2R1。

[0049] According to this embodiment, preferably, the radius R3 of the circular hole should satisfy the following relationship with the outer radius R1 and the inner radius R2 of the annulus:

[0050]

[0051] According to this embodiment, preferably, the first and last annular support units in the circumferential direction of the annular support body are connected by a connecting unit to form a ring structure.

[0052] According to this embodiment, preferably, the S-shaped connecting ribs between the axially arranged annular supports are arranged in an alternating pattern.

[0053] According to this embodiment, preferably, the vascular stent is made by laser engraving using medical 316L stainless steel microtubes, L605 cobalt-chromium alloy microtubes, shape memory alloy microtubes, or biodegradable magnesium alloy microtubes.

[0054] Laser engraving is a process based on CNC technology, using laser as the processing medium. The material undergoes instantaneous melting and vaporization under laser irradiation, achieving the desired processing effect. Laser processing characteristics include: no contact with the material surface, no mechanical movement, no surface deformation, and generally no need for fixation. It is unaffected by the elasticity or flexibility of the material, making it suitable for processing soft materials. It offers high precision, high speed, and a wide range of applications. Laser cutting uses a focusing lens to focus a CO2 laser beam onto the material surface, melting it. Simultaneously, compressed gas coaxial with the laser beam blows away the molten material, causing the laser beam and material to move relative to each other along a specific trajectory, thus forming a cut of a certain shape. Laser cutting technology is widely used in the processing of both metallic and non-metallic materials, significantly reducing processing time, lowering costs, and improving workpiece quality. Pulsed lasers are suitable for metallic materials, while continuous lasers are suitable for non-metallic materials; the latter is an important application area for laser cutting technology.

[0055] Laser engraving and laser cutting have the following advantages:

[0056] Wide range of applications: CO2 lasers can engrave and cut almost any non-metallic material. And the price is low!

[0057] Safe and reliable: Utilizing non-contact processing, it avoids mechanical compression or stress on the material. There are no "tool marks," so it does not damage the surface of the workpiece; it does not deform the material.

[0058] Precise and meticulous: the machining accuracy can reach 0.02mm;

[0059] Economical and environmentally friendly: The beam and spot diameter are small, generally less than 0.5mm; cutting and processing save materials and are safe and hygienic;

[0060] Consistent Results: Ensure that the processing results of the same batch are completely consistent.

[0061] High speed and efficiency: It can immediately perform high-speed engraving and cutting based on the computer-generated drawings.

[0062] Low cost: Laser processing is cheaper for small-batch processing services as it is not limited by the number of processing orders.

[0063] 316 stainless steel: Due to the addition of molybdenum, 316 stainless steel has particularly good corrosion resistance, atmospheric corrosion resistance and high temperature strength, and can be used under harsh conditions; it also has excellent work hardening properties (non-magnetic).

[0064] L605 Cobalt-Chromium Alloy: L605 superalloy is the most suitable cobalt-based alloy for machining and forming in continuous 1800°F operating environments. Due to its long service life and wide range of applications, this alloy has been used extensively in various working conditions, thus it is a material with highly versatile properties. When exposed to prolonged moderate temperatures, L605 superalloy exhibits a slight decrease in room temperature ductility.

[0065] Magnesium alloys possess excellent mechanical properties. The elastic modulus of magnesium alloys (41-45 GPa) is closest to that of human bone (3-21 GPa), which can alleviate stress shielding effects. Magnesium ions produced by the degradation of magnesium alloys are essential elements for the human body and act as catalysts for various enzymes. The local alkaline environment created by degradation can effectively inhibit inflammation, exhibiting good anti-platelet deposition effects and a low tendency to thrombosis. They also possess good biocompatibility.

[0066] According to this embodiment, preferably, the number of the annular supports is determined according to the length of the bracket.

[0067] According to this embodiment, preferably, the drug contained is flunarizine, rapamycin, or paclitaxel.

[0068] According to this embodiment, preferably, the number and radius of the circular holes are determined based on the required metal coverage and drug loading or the amount of fixative developer.

[0069] The metal coverage and drug loading, as well as the amount of fixed developer, can be changed by altering the number and radius of their circumferential arrangement.

[0070] The number of circular support units arranged along the axial direction of the vascular stent is greater than 2. This number of arrangements determines the axial length of the vascular stent. Therefore, the specific number of axial arrangements is determined according to the clinical application requirements for the axial length of the stent.

[0071] The number of circular support units arranged along the circumference of the vascular stent is greater than 2. This number of arrangements determines the diameter of the vascular stent. Therefore, the specific number of circumferential arrangements is determined according to the needs of the stent diameter in clinical applications. Specific implementation examples:

[0073] In this embodiment, a schematic diagram of the circumferential unfolding of the vascular stent is shown below. Figure 1 As shown, the vascular stent is composed of 8 annular supports connected by 7 sets of S-shaped connecting ribs. Each set of S-shaped connecting ribs is composed of 3 S-shaped connecting units arranged circumferentially. Each support is composed of 6 annular support units of the same shape and 6 S-shaped connecting units of the same shape.

[0074] The eight annular supports are designated as follows: first annular support 1, second annular support 2, third annular support 3, fourth annular support 4, fifth annular support 5, sixth annular support 6, seventh annular support 7, and eighth annular support 8. The seven groups of S-shaped connecting ribs are designated as follows: first group S-shaped connecting rib 11, second group S-shaped connecting rib 12, third group S-shaped connecting rib 13, fourth group S-shaped connecting rib 14, fifth group S-shaped connecting rib 15, sixth group S-shaped connecting rib 16, and seventh group S-shaped connecting rib 17. The first annular support 1 is connected to the adjacent second annular support 2 by a first set of S-connecting ribs 11. The second annular support 2 is connected to the adjacent third annular support 3 by a second set of S-connecting ribs 12. The third annular support 3 is connected to the adjacent fourth annular support 4 by a third set of S-connecting ribs 13. The fourth annular support 4 is connected to the adjacent fifth annular support 5 by a fourth set of S-connecting ribs 14. The fifth annular support 5 is connected to the adjacent sixth annular support 6 by a fifth set of S-connecting ribs 15. The sixth annular support 6 is connected to the adjacent seventh annular support 7 by a sixth set of S-connecting ribs 16. The seventh annular support 7 is connected to the adjacent eighth annular support 8 by a seventh set of S-connecting ribs 17. The first group of S-shaped connecting bars 11, the second group of S-shaped connecting bars 12, the third group of S-shaped connecting bars 13, the fourth group of S-shaped connecting bars 14, the fifth group of S-shaped connecting bars 15, the sixth group of S-shaped connecting bars 16, and the seventh group of S-shaped connecting bars 17 are arranged alternately. Combined with... Figure 1Specifically, each of the following annular support bodies—the first, second, third, fourth, fifth, sixth, seventh, and eighth—has six vertically arranged annular support units arranged from top to bottom in the circumferential direction: 1. The connection between the first and second annular support bodies is the first vertically arranged annular support unit in the first annular support body 1. The third and fifth annular support units are respectively connected to the corresponding first vertically arranged annular support units in the second annular support body 2. The third and fifth annular support units are connected by S-shaped connecting ribs. The connection between the second and third annular support bodies is the second vertically arranged annular support unit in the first annular support body 1. The sixth and fourth annular support units are respectively connected to the second annular support unit in the third annular support 3, which is vertically aligned from top to bottom in the circumferential direction. The sixth and fourth annular support units are connected by S-shaped connecting ribs. The connection between the third and fourth annular support 3 and the first and second annular support 2 is the same as the connection between the first and second annular support 1. The connection between the fourth and fifth annular support 5 and the second and third annular support 3 is the same as the connection between the fifth and sixth annular support 6 and the first and second annular support 1. The connection between the sixth and seventh annular support 7 and the second and third annular support 3 is the same as the connection between the seventh and eighth annular support 8 and the first and second annular support 1. The staggered arrangement of the S-shaped connecting ribs in this invention provides better flexibility, facilitating stent delivery to the lesion site and better conforming to the lesion site of tortuous blood vessels.

[0075] like Figure 2As shown, the vascular stent of the present invention has an axial zero Poisson's ratio structure, and the axial length change is almost zero during compression and expansion. The first annular support unit 21 and the second annular support unit 23 are connected by the first S-shaped connecting unit 22. The second annular support unit 23 and the third annular support unit 25 are connected by the second S-shaped connecting unit 24. The third annular support unit 25 and the fourth annular support unit 27 are connected by the third S-shaped connecting unit 26. The fourth annular support unit 27 and the fifth annular support unit 29 are connected by the fourth S-shaped connecting unit 28. The fifth annular support unit 29 and the sixth annular support unit 31 are connected by the fifth S-shaped connecting unit 30. The sixth annular support unit 31 and the first annular support unit 21 are connected by the sixth S-shaped connecting unit 32, forming an annular support body including six annular support units and six S-shaped connecting units.

[0076] like Figure 3 As shown, the present invention provides a vascular stent with almost zero axial length change during compression and expansion. R1 is the outer radius of the annular support unit, R2 is the inner radius of the annular support unit, R3 is the radius of the evenly distributed circular holes on the annular support unit that can be used for drug loading or fixation of contrast agents, and L1 is the radial length from the crest to the trough of the S-shaped connecting unit.

[0077] The radial length L1 from the crest to the trough of the S-shaped connecting unit is between twice the inner radius R2 and twice the outer radius R2 of the annulus. The annular support unit has evenly distributed circular holes that can be used for drug loading or fixing contrast agents, and the radius R3 of the holes should be less than half of (outer radius R1 - inner radius R2). Contrast agents can be used to more clearly observe the relationship between the vascular stent and the lesion location during CT angiography. The loaded drugs, such as flunarizine, rapamycin, or paclitaxel, can effectively inhibit intimal hyperplasia, promote blood circulation, and treat some cardiovascular and cerebrovascular diseases.

[0078] like Figure 4 , 5 As shown, the vascular stent with an axial zero Poisson's ratio structure of the present invention is made of medical 316L stainless steel microtubes, L605 cobalt-chromium alloy microtubes, shape memory alloy microtubes, or biodegradable magnesium alloy microtubes by laser engraving and laser cutting, thus maintaining the integrity of the stent.

[0079] The vascular stent structure includes several annular supports and several sets of S-shaped connecting ribs. The connecting ribs between adjacent annular supports are composed of S-shaped connecting units. The annular support units are arranged circumferentially along the stent, and adjacent annular support units are connected by S-shaped connecting units to form an annular support. The annular support units have evenly distributed circular holes that can be used for drug loading or fixing contrast agents.

[0080] In practical applications, the length of a support can be changed by altering the number of annular supports arranged axially, thus determining the axial length of the vascular stent. Therefore, the specific number of annular supports arranged axially is determined based on the clinical application requirements for the stent's axial length. The circumferential arrangement of the annular support unit 21 and the S-shaped connecting unit 22 determines the diameter of the vascular stent. Therefore, the specific circumferential arrangement is determined based on the clinical application requirements for the stent's diameter. The metal coverage, drug loading, and amount of contrast agent can be changed by altering the number of small holes arranged circumferentially on the annulus and the radius R3. The contrast agent allows for a clearer observation of the relationship between the vascular stent and the lesion location during CT angiography. The loaded drugs, such as flunarizine, rapamycin, or paclitaxel, can effectively inhibit intimal hyperplasia, promote blood circulation, and treat some cardiovascular and cerebrovascular diseases.

[0081] Figure 6 The diagram shown is a simulation of ABAQUS vascular stent expansion. Taking a radial expansion of 0.3 mm as an example, the axial length of the stent before expansion is 7.49997 mm, and the length of the stent after expansion is 7.49855 mm, with an axial shortening of 0.00142 mm, which is close to zero. It can be seen that the vascular stent described in this invention has almost zero change in axial length during compression and expansion, and the overall structure exhibits a zero Poisson's ratio effect. This invention can improve the positioning accuracy during implantation, completely cover the lesion site, reduce stent damage to vascular tissue, reduce the probability of in-stent restenosis, inhibit intimal hyperplasia, and promote blood circulation.

[0082] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0083] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the present invention should be included within the scope of protection of the present invention.

Claims

1. A vascular stent with an axial zero Poisson's ratio structure, characterized in that, It includes several annular supports; The annular support body includes several annular support units, which are arranged circumferentially, and adjacent annular support units are connected by connecting units; Several annular supports are arranged along the axial direction, and adjacent annular supports are connected by connecting ribs. The annular support unit has evenly distributed circular holes for loading drugs or fixing contrast agents. Adjacent circular support units are connected by S-shaped connecting units; The S-shaped connecting ribs between the axially arranged annular supports are staggered. The length L1 from the crest to the trough of the S-shaped connecting unit is between twice the outer radius R1 and twice the inner radius R2 of the annulus, satisfying the following relationship: 2R2 <L1<2R1; The radius R3 of the circular hole should satisfy the following relationship with the outer radius R1 and the inner radius R2 of the annulus: ； The annular support body has a first and last annular support unit connected by a connecting unit to form a ring structure.

2. The vascular stent with an axial zero Poisson's ratio structure according to claim 1, characterized in that, The vascular stent is made by laser engraving using medical 316L stainless steel microtubes, L605 cobalt-chromium alloy microtubes, shape memory alloy microtubes, or biodegradable magnesium alloy microtubes.

3. The vascular stent with an axial zero Poisson's ratio structure according to claim 1, characterized in that, The number of annular supports is determined according to the length of the bracket.

4. The vascular stent with an axial zero Poisson's ratio structure according to claim 1, characterized in that, The listed drugs are flunarizine, rapamycin, or paclitaxel.

5. The vascular stent with an axial zero Poisson's ratio structure according to claim 1, characterized in that, The number and radius of the circular holes are determined according to the required metal coverage and drug loading or the amount of fixative.

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