Long-section peripheral vascular stent

Abstract

The invention discloses a long-section peripheral vascular stent which is used for treating diseases such as peripheral vascular stenosis below knees and the like and solves the problems that an existing stent is difficult to introduce into peripheral blood vessels and lacks effective support. The stent has two states of a pressing and holding state and an expansion state with different section radiuses, is implanted into a peripheral vascular affected part in the pressing and holding state, and supports a blood vessel at the affected part in the expansion state. Sufficient radial yield strength is provided through a plurality of supporting rings so as to adapt to the characteristics that the peripheral blood vessel is large in elasticity and thick in outer base layer. And the stent is prepared from a degradable material, so that mechanical support required in the early stage of fusion is met, the stent also has relatively high strength and toughness, and the stent can be degraded in vivo, so that the use safety is greatly improved. Moreover, the pattern of the stent is optimized, so that the circumferential rotation phenomenon of the longer intravascular stent in the expansion process is improved, and the damage to the vascular wall in the implantation process is reduced to the greatest extent.

Description

Technical Field

[0001] The present application belongs to the field of interventional therapy, and specifically relates to a long-segment peripheral vascular stent. Background Art

[0002] Peripheral arterial disease (PAD) is a vascular disease that affects more than 200 million people worldwide. Its most severe manifestation is critical limb-threatening ischemia (CLTI). CLTI covers a series of serious symptoms, such as occlusion of the below-the-knee artery, lower limb rest pain caused by insufficient blood supply to the limbs, tissue damage and even gangrene. The high disability and mortality rates caused by CLTI undoubtedly put a heavy burden on the medical system. Despite the huge medical expenses, the five-year survival rate of patients is still worrying. It is particularly noteworthy that traditional treatment methods for CLTI-related below-the-knee artery (BTK) lesions have significant limitations. Although endovascular treatment methods such as POBA (balloon angioplasty), DCB (drug-coated balloon), DES (drug-eluting stent), and volume reduction are widely used, these methods all have certain defects and cannot achieve ideal treatment effects.

[0003] Below-the-knee artery (BTK) lesions are characterized by long lesions, small vessel diameter, severe calcification, and high severity. They are one of the difficulties in endovascular treatment of lower limbs. Existing technologies for endovascular treatment of BTK disease include POBA (balloon angioplasty), DCB (drug-coated balloon), DES (drug-eluting stent), volume reduction, etc., but they all have certain limitations. For local BTK lesions, compared with POBA or BMS, DES stents improve the primary patency rate, TLR-free rate, and limb salvage rate, and reduce the risk of re-intervention and amputation.

[0004] However, the peripheral blood vessels are highly elastic, with thick outer base layers and high blood vessel elasticity, requiring a stent with greater support force; and the peripheral blood vessel stenosis is longer, so correspondingly, the stent needs to be longer. Due to the increase in length, the vascular stents in the prior art are prone to uneven expansion. Summary of the invention

[0005] The purpose of the present invention is to provide a peripheral stent for treating diseases such as below-the-knee peripheral vascular stenosis, to solve the problem that existing stents are difficult to introduce into peripheral blood vessels and lack effective support, and by optimizing the pattern of the stent, to improve the circumferential rotation phenomenon of longer vascular stents during the expansion process, thereby minimizing the damage to the blood vessel wall during the implantation process.

[0006] To achieve the above objectives, this application adopts the following technical solutions: A long-segment peripheral vascular stent comprises: a curved arc and a connecting arc; the curved arc is an axisymmetric arc, the connecting arc comprises an arc portion and a connecting portion, the arc portion and the curved arc have exactly the same shape, one end of the connecting portion is arranged outside the arc portion, and the other end extends outward; the connecting arc and the curved arc are connected end to end to form a closed support ring, and adjacent support rings are connected to each other, thereby forming a tubular support structure.

[0007] Furthermore, the adjacent curved arcs, the arc-shaped parts, and the curved arcs on the same support ring are all centrally symmetrical figures, and the connection point is the rotation center.

[0008] Furthermore, the connection arcs are distributed at intervals on the same support ring and are distributed alternately on adjacent support rings, so that the connection parts are inclined to the axial direction.

[0009] Furthermore, the number of curved arcs between adjacent connecting arcs on the same support ring is the same.

[0010] Furthermore, in the connecting arcs, the number of curved arcs between adjacent connecting arcs on the same supporting ring is an even number, so that adjacent connecting parts are located on both sides of the supporting ring.

[0011] Furthermore, the connection part is inclined relative to the connection line (aa line) of the rotation center of each arc segment of the support ring, and the connection parts on both sides of the support ring have the same angle with the aa line, but the connection arcs on both sides of the support ring are inclined in opposite directions. And among the connection parts, the inclination angles of the groups of connection parts with the same inclination direction are all the same.

[0012] This application has at least the following beneficial effects.

[0013] The support ring formed by connecting arc units of different shapes has good compressibility and can deform circumferentially. It is particularly suitable for peripheral blood vessels with longer lengths and more complex vascular conditions, improving the problem of uneven expansion of different parts of longer catheters. At the same time, the structure of the connecting arc also optimizes the connection between the support rings, and can bend moderately based on the vascular conditions, thereby improving the smoothness of delivery. In addition, it also has high circumferential strength, overcoming the circumferential rotation phenomenon during the expansion process.

[0014] In addition, the present application uses zinc alloy material as the main structure, which itself and its degradation products are non-toxic and have good tissue compatibility and blood compatibility. The peripheral vascular stent made of degradable zinc alloy material can meet the mechanical support required in the early stage of fusion, and its mechanical properties meet the strength and toughness requirements of medical implant materials, while being degradable in vivo. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram schematically shows a circumferential rotation defect after expansion in the prior art; Figure 2 The schematic diagram of the structure of the curved arc in the present application is shown schematically; Figure 3 The schematic diagram of the structure of the connection arc in the present application is shown schematically; Figure 4 A schematic diagram of the structure of the connection state of the curved arc and the connecting arc in the present application is schematically shown; Figure 5 The structural diagram of the support ring in the present application is schematically shown; Figure 6 The plan view of the present application is schematically shown; Figure 7 The schematic diagram shows the physical image of the present application after the compression and expansion; Figure 8 The finite element simulation diagram of the present application after expansion is schematically shown.

[0017] Among them: 1-support ring, 11-curved arc, 12-connecting arc, 121-arc-shaped part, 122-connecting part. DETAILED DESCRIPTION

[0018] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0019] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0020] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present invention; however, it should be clear to those skilled in the art that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, and methods are omitted to avoid obstructing the description of the present invention with unnecessary details. Example

[0021] A long-segment peripheral vascular stent is formed by connecting a number of identical curved arcs 11 and connecting arcs 12 to each other. A closed support ring 1 is formed by the combination of the curved arcs 11 and the connecting arcs 12. A number of support rings 1 are connected to each other to form a hollow tubular structure. The stent has two states, a compressed state and an expanded state, with different cross-sectional radii. It is implanted in the affected part of the peripheral blood vessel in the compressed state and supports the affected blood vessel in the expanded state. Sufficient radial yield strength is provided by a number of support rings 1 to adapt to the characteristics of large elasticity and thick outer base of the peripheral blood vessel; and the stent is made of degradable materials. While meeting the mechanical support required in the early stage of fusion, it also has high strength and toughness, and can also be degraded in the body, greatly improving the safety of use.

[0022] Peripheral blood vessels are different from coronary blood vessels. They are often more elastic and longer. Currently, the vascular stents on the market are mainly designed for coronary blood vessels. As for peripheral vascular stents, most of them are simply extended based on coronary stents. However, for long segments of peripheral blood vessels, the simple extension of coronary stents cannot fully meet the requirements of support strength and delivery flexibility.

[0023] In addition, the applicant discovered that the prior art has new technical problems. The stent is prone to circumferential rotation during the compression and expansion process. Circumferential rotation refers to the fact that when the support ring 1 expands, the support ring 1 rotates to varying degrees in the circumferential direction. This is not obvious in coronary stents. For long-segment stents, the longer the stent, the more obvious the circumferential rotation phenomenon is. Moreover, during the torsion process, the circumferential rotation process will promote adverse interactions between the arterial wall and the device, which may cause damage to the arterial wall and increase the risk of treatment failure.

[0024] It should be noted that the long segment here is longer than the coronary artery. For example, the length of the coronary stent is generally 8~40mm, while the length of the peripheral vascular stent can usually reach 170mm. Technical personnel in this field can flexibly choose stents of different lengths based on different parts of use.

[0025] Preferably, the length of the long-segment peripheral vascular stent is 50-200 mm.

[0026] like Figure 1 The figure shows a coronary stent in the prior art, which is obtained by extending it and then compressing and expanding it. Figure 1 The connection points between different parts of the stent are taken as the connection points. The connection point on the left is used as the starting point to construct a horizontal line. This horizontal line is the connection line of each connection point before crimping. As a reference line, the starting point and the connection point at the distal end are connected to each other into a straight line. This line is the connection line of the connection points after crimping and expansion. Obviously, after crimping and expansion, the stent rotates circumferentially. The farther apart, the more obvious the degree of rotation. If circumferential rotation occurs during the operation, and the blood vessel itself is curved, the stent will further strengthen the adverse interaction with the arterial wall during the torsion process, making it more likely to cause arterial wall damage.

[0027] In order to avoid the above problems, this application adopts different technical solutions.

[0028] The stent of the present application is formed by connecting arc units, and the arc units have two different forms, namely, a curved arc 11 and a connecting arc 12. Figure 2 As shown, the curved arc 11 is an axisymmetric arc, with both ends of the curved arc 11 facing the same side, appearing as an arc unit similar to a U-shape or a C-shape. The both ends of the curved arc 11 can be opened, and the middle part of the curved arc 11 is a circular arc or an elliptical arc, which avoids local stress concentration after opening and ensures balanced force.

[0029] like Figure 4As shown, the arc portion 121 of the connecting arc 12 has exactly the same shape as the curved arc 11. The connecting arc 12 and the curved arc 11 are connected end to end to form a closed support ring 1. The adjacent curved arcs 11 and the arc portion 121 of the connecting arc 12 and the curved arc 11 form a centrally symmetrical figure, which is rotationally symmetrical with the connection point between the two as the center, thereby ensuring that the support ring 1 is evenly expanded in the circumferential direction.

[0030] The difference between the connecting arc 12 and the curved arc 11 is that the connecting arc 12 has a connecting portion 122, such as Figure 3 As shown, the connection portion 122 is fixed to the middle portion of the connection arc 12 and extends outward, and the connection portions 122 of the connection arcs 12 on adjacent support rings 1 are connected to each other, thereby connecting the support rings 1 into a tubular stent.

[0031] It should be noted that the side of the connecting portion 122 on the connecting arc 12 that extends outward is the side opposite to the opening of the connecting arc 12 .

[0032] Furthermore, the connecting arcs 12 are distributed at intervals on the same support ring 1 and staggered on adjacent support rings 1, thereby avoiding mutual interference during the pressing, gripping, expansion and bending processes and improving the flexibility of transportation.

[0033] Specifically, the connecting arcs 12 on adjacent support rings 1 are not in the same axial direction. Figure 6 It can be seen from the plane unfolded view that the connecting arcs 12 on adjacent support rings 1 are not on the same horizontal line, and there is at least a width of the curved arc 11 between them, so that the connecting portion 122 is inclined to the horizontal line, and the inclination angles are the same.

[0034] Specifically, the connection arcs 12 located on the same support ring 1 are distributed at intervals, such as Figure 5 As shown, line aa is the line where the curved arc 11 and the connecting arc 12 are connected in the plane unfolding state. Line aa is a ring when in use. The plane constructed by line aa is perpendicular to the axis direction. Figure 5 The plane is unfolded to be a straight line, and adjacent support rings 1 on the same support ring 1 are spaced by an even number of curved arcs 11, so that on the same support ring 1, the connecting arc 12 and its two closest connecting rings are respectively located on both sides of the aa line, and the connecting parts 122 on both sides of the connecting arc 12 are inclined in opposite directions, and the extended lines of the connecting parts 122 on both sides have the same angles α and β with the aa line.

[0035] Of course, since there is no supporting ring 1 connected to the other side of the end supporting ring 1, the number of curved arcs 11 between adjacent supporting rings 1 on the end supporting ring 1 is an even multiple of that of the middle supporting ring 1, and there is no connecting portion 122 on the outward side.

[0036] Preferably, adjacent support rings 1 on the same support ring 1 are spaced apart by two curved arcs 11 , and adjacent support rings 1 on the end support rings 1 are spaced apart by four curved arcs 11 .

[0037] Additionally, since the connecting arcs 12 are evenly distributed on both sides of the support ring 1 and the inclination angles of the connecting portions 122 on both sides are also different, both clockwise and counterclockwise rotation will be restricted by the connecting portions 122, thereby improving axial stability and reducing the occurrence of circumferential rotation.

[0038] Of course, the connecting portion 122 can be either a straight line or a curve. In this embodiment, a straight line is used as an example for description.

[0039] like Figure 7 The figure shows an enlarged view of the peripheral stent of this embodiment after compression and expansion. Figure 1 It can be seen from the above that the peripheral support of this embodiment does not undergo significant circumferential rotation, which indicates that the structure of this application effectively overcomes the occurrence of circumferential rotation. Figure 8 It can be seen that during the expansion process of the peripheral support structure, each part is evenly stressed and there is no stress concentration location, which means that the combined structure of the curved arc 11 and the connecting arc 12 used in the present application meets the requirements of expansion uniformity while reducing the occurrence of defects.

Claims

1. A long-segment peripheral vascular stent, characterized in that: include: Curved arc, connecting arc; The curved arc is an axisymmetric arc, the connecting arc comprises an arc portion and a connecting portion, the arc portion is completely the same shape as the curved arc, one end of the connecting portion is arranged outside the arc portion, and the other end extends outward; The connecting arc and the curved arc are connected end to end to form a closed support ring, and adjacent support rings are connected to each other to form a tubular support structure.

2. A long-segment peripheral vascular stent according to claim 1, characterized in that: In the support ring, the adjacent curved arcs, the arc-shaped parts, and the curved arcs on the same support ring are all centrally symmetrical figures, and the connection point is the rotation center.

3. A long-segment peripheral vascular stent according to claim 2, characterized in that: The connecting arcs are distributed at intervals on the same supporting ring and are distributed alternately on adjacent supporting rings.

4. A long-segment peripheral vascular stent according to claim 3, characterized in that: In the connecting arcs, the number of curved arcs between adjacent connecting arcs on the same supporting ring is the same.

5. The long-segment peripheral vascular stent according to claim 4, characterized in that: In the connecting arcs, the number of curved arcs between adjacent connecting arcs on the same supporting ring is an even number, so that adjacent connecting parts are located on both sides of the supporting ring.

6. The long-segment peripheral vascular stent according to claim 3, characterized in that: Among the connecting arcs, the connecting arcs located on adjacent supporting rings are staggered so that the connecting parts are inclined to the axial direction.

7. The long-segment peripheral vascular stent according to claim 6, characterized in that: The connecting part is inclined relative to the connecting line (aa line) of the rotation centers of the arc segments of the support ring. The connecting parts on both sides of the support ring have the same angle with the aa line, but the connecting arcs on both sides of the support ring are inclined in opposite directions.

8. The long-segment peripheral vascular stent according to claim 7, characterized in that: In the connection parts, the inclination angles of the connection parts of the same arrays with the same inclination direction are all the same.

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