A degradable vascular stent with uniform expansion and compression performance

Abstract

A degradable vascular stent with uniform tensile and compressive expansion performance. The present invention relates to the technical field of medical devices, and specifically to a degradable vascular stent with uniform tensile and compressive mechanical deformation behavior. It is composed of a number of basic structural units with uniform tensile and compressive expansion arranged circumferentially and axially along the vascular stent. The basic structural unit with uniform tensile and compressive expansion includes a concave structure and a hexagonal honeycomb structure. The purpose of the present invention is to provide a degradable vascular stent with uniform tensile and compressive expansion. Within a certain radial expansion range, as the radial diameter increases, there will be no axial contraction, which is convenient for the positioning of the implant during the implantation surgery. And after implantation, when subjected to vascular compressive stress, it will expand radially, thereby providing good support and reducing the late restenosis rate of blood vessels. The present invention can be prepared by additive manufacturing technology. The vascular stent can adopt a degradable material with good biocompatibility, and the stent will eventually completely degrade in the body, and its degradation products are absorbed and metabolized by the human body.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly relates to a degradable vascular stent with tensile and compressive uniform expansion performance. Background Art

[0002] In recent years, with the acceleration of the modern life rhythm and the transformation of the dietary structure, the prevalence of vascular obstructive diseases has shown a continuous growth trend and has become an important hidden danger threatening public health. In the field of vascular disease treatment, stent interventional therapy has become one of the mainstream clinical treatment methods due to its minimally invasive and immediate curative effect advantages. However, while existing stents play a mechanical support role, the mechanical damage to the blood vessel wall may be caused during their expansion process, leading to local inflammatory reactions and abnormal intimal hyperplasia, and ultimately triggering the clinical complication of in-stent restenosis. Research shows that such restenosis phenomena are closely related to the imbalance of stress distribution after stent implantation. Therefore, inhibiting in-stent restenosis has become the core topic in the research and development of vascular stent technology, and optimizing the geometric configuration and mechanical property distribution of stents has become an important breakthrough direction for improving the long-term curative effect of stents.

[0003] As a precision medical device, vascular stents play an important role in the medical field, but at the same time, they also face some challenges. Its function is to mechanically support and expand stenotic or occluded blood vessels, restore blood flow, provide continuous radial support force, inhibit vascular elastic recoil, and at the same time inhibit intimal hyperplasia and restenosis. However, due to the limitations of its structure, local stress will be too high during expansion, which may lead to stent fracture or blood vessel damage.

[0004] The tensile and compressive uniform expansion structure is a structure with switchable positive and negative Poisson's ratios. When this structure is under uniaxial tension or compression, it will expand in the transverse direction, that is, it shows a negative Poisson's ratio effect during tension and a positive Poisson's ratio effect during compression. During the implantation operation, the actual position of the traditional vascular stent deviates from the expectation due to axial contraction during radial expansion, and doctors need to repeatedly adjust it during the operation. However, this structure eliminates axial contraction, so that the length of the stent is basically unchanged after expansion, and doctors can accurately position it at one time, reducing the surgical risk; moreover, after the traditional vascular stent is implanted into the human body, it will radially contract when compressed, which may lead to blood vessel restenosis. Different from traditional vascular stents, the tensile and compressive uniform expansion structure can expand radially when it is stretched or compressed, which is more conducive to better positioning of the vascular stent during implantation and playing a fixed support role after implantation. The switchable effect of positive and negative Poisson's ratios of the tensile and compressive uniform expansion material stems from its special internal structure, that is, the concave structure and the hexagonal honeycomb structure. Since the tensile and compressive uniform expansion structure is relatively complex, and the additive manufacturing technology has the characteristics of high design freedom and the ability to precisely control the microstructure of materials, the additive manufacturing technology is very suitable for preparing the tensile and compressive uniform expansion structure. Summary of the Invention

[0005] By providing a degradable vascular stent with tensile and compressive uniform expansion performance, the present invention solves the technical problems that traditional vascular stents with auxetic structures are not easy to position during implantation and cannot provide good support when subjected to vascular contraction stress after implantation, and reduces the probability of in-stent restenosis. The degradable vascular stent with tensile and compressive uniform expansion performance can expand uniformly under the action of tensile and compressive stresses, significantly improving the conformity between the stent and the vascular intima, the expansion consistency and the long-term service stability, and is suitable for the treatment of vascular stenosis or occlusive diseases.

[0006] To achieve the above object, the present invention adopts the following technical solution: A degradable vascular stent with tensile and compressive uniform expansion performance is composed of a number of basic tensile and compressive uniform expansion structural units arranged circumferentially and axially along the vascular stent to form a tensile and compressive uniform expansion vascular stent structure;

[0007] The basic tensile and compressive uniform expansion structural unit is formed by combining an inward concave structure with a hexagonal honeycomb structure; the hexagonal honeycomb structure is the outer layer, and there are gaps at both its upper and lower ends; the inward concave structure is inserted into the gaps at both the upper and lower ends of the hexagonal honeycomb structure, so as to have a tensile and compressive uniform expansion mechanical deformation effect;

[0008] The tensile and compressive uniform expansion vascular stent structure is made of a degradable material, and the tensile and compressive uniform expansion vascular stent structure not only has a tensile and compressive uniform expansion effect but also can degrade in the body.

[0009] The inward concave structure includes a T-shaped rod and an inclined rod; the horizontal part of the T-shaped rod is located outside the hexagonal honeycomb structure; after the vertical part of the T-shaped rod is inserted from the gap, the vertices are respectively connected to the sides of the hexagonal honeycomb structure through two inclined rods.

[0010] The number of the basic tensile and compressive uniform expansion structural units arranged circumferentially along the vascular stent is 4 to 8.

[0011] The number of the basic tensile and compressive uniform expansion structural units arranged axially along the vascular stent is greater than 2.

[0012] The degradable material is a metal material, a polymer material or a metal-polymer composite material, so that the vascular stent can be completely degraded in the body after completing its treatment task, and the degradation products can be absorbed and metabolized by the human body.

[0013] The metal material is magnesium and its alloys, iron and its alloys, zinc and its alloys; the polymer material is polylactic acid, polyglycolic acid, polycaprolactone.

[0014] Since degradable materials usually have relatively weak mechanical properties, by reducing the number of arrangements of the basic tensile and compressive uniform expansion structural units, the cross-sectional area of the stent structure can be increased, thereby enhancing the mechanical support ability of the degradable stent for the blood vessel wall.

[0015] The tension-compression uniform expansion degradable vascular stent is composed of tension-compression uniform expansion basic structural units arranged axially, and the number of arranged units exceeds 2. The number of these units directly determines the axial length of the stent. Therefore, in clinical applications, the specific axial arrangement number will be determined according to the actual requirement for the axial length of the stent.

[0016] The present invention has the following beneficial effects: The degradable vascular stent with tension-compression uniform expansion performance can not only adapt to the contraction and relaxation stresses of blood vessels, provide uniform and stable mechanical support, and reduce the risk of restenosis, but also achieve stage functions through degradable materials - ensuring the patency of the lumen in the early stage, and gradually transferring the load to the newly formed tissue with the degradation of the material in the later stage, promoting the natural repair of blood vessels. At the same time, it avoids complications such as inflammation and thrombosis caused by the long-term retention of metal stents, providing a safer and more physiologically demanding solution for the treatment of cardiovascular diseases. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the structure of the tension-compression uniform expansion basic structural unit;

[0018] Figure 2 It is a figure obtained by superimposing the structures of the tension-compression uniform expansion basic structural unit in the two-dimensional direction;

[0019] Figure 3 It is Figure 2 a structure formed by curling and thickening.

[0020] Figure 4 It is a curve reflecting the Poisson's ratio effect of the tension-compression uniform expansion basic structural unit. Detailed Description of the Embodiments

[0021] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0022] As Figure 1 shown, when the tension-compression uniform expansion basic structural unit is subjected to longitudinal compressive stress, the overall structure is equivalent to a traditional hexagonal honeycomb structure. Therefore, the structure will expand laterally, showing a positive Poisson's ratio effect. When subjected to longitudinal tensile stress, the overall structure can be regarded as a concave honeycomb structure. Therefore, the structure will also expand laterally, showing a negative Poisson's ratio effect. The tension-compression uniform expansion structure is formed by thickening after two-dimensional superposition of many figures such as Figure 1 shown. When subjected to in-plane tensile or compressive stress in the longitudinal direction, in-plane lateral expansion will occur; the structure shown in Figure 2 is curled into the three-dimensional tubular structure shown in Figure 2 shown. When the axial direction is subjected to tensile stress or compressive stress, radial expansion will also occur. Figure 3 When the axial direction is subjected to tensile stress or compressive stress, radial expansion will also occur.

[0023] The tension-compression uniform expansion structure of the present invention can be thickened by stacking the figure shown in Figure 1 in the drawing (or other two-dimensional figures with tension-compression uniform expansion effect) in the two-dimensional direction, and the structure can be bent into a cylindrical shape shown in Figure 3 according to actual needs.

[0024] The tension-compression uniform expansion structure involved in the present invention includes all structures with switchable positive and negative Poisson's ratios, including but not limited to the structures shown in the drawings.

[0025] See Figure 3 , Figure 3 It is a schematic diagram of the arrangement of the tension-compression uniform expansion basic structure units along the circumferential and axial directions of the stent. The arrangement of the tension-compression uniform expansion basic structure units along the circumferential and axial directions of the stent constitutes the tension-compression uniform expansion degradable stent structure, and the number of axial arrangements determines the axial length of the vascular stent. The specific number of axial arrangements is determined according to the requirement for the axial length of the vascular stent in clinical applications.

[0026] From Figure 4 , it can be seen that under tensile stress (strain is positive), the structure shows a negative Poisson's ratio and the volume expands; under compressive stress (strain is negative), the structure shows a positive Poisson's ratio and the volume also expands. Thus, it is verified that this structure can achieve an expansion effect under both tensile and compressive stress conditions.

[0027] The tension-compression uniform expansion vascular stent structure provided by the present invention can be applied to degradable materials, mainly including three categories: metal materials, polymer materials, and composite materials. The degradable materials have good biocompatibility, reduce the risk of complications, and can be degraded and absorbed in the body. Ferroalloys, zinc alloys, magnesium alloys, and polylactic acid belong to the above-mentioned degradable materials.

[0028] The tension-compression uniform expansion degradable vascular stent structure provided in the present invention can be manufactured by an additive manufacturing method.

Claims

1. A degradable vascular stent with uniform expansion and compression performance, characterized in that, A tension-compression uniform expansion vascular stent structure is formed by arranging a number of tension-compression uniform expansion basic structural units circumferentially and axially along the vascular stent. The tension-compression uniform expansion basic structural unit is formed by combining an inner concave structure and a hexagonal honeycomb structure; the hexagonal honeycomb structure is the outer layer, with gaps opened at both its upper and lower ends; the inner concave structure is inserted into the gaps at both the upper and lower ends of the hexagonal honeycomb structure, so as to have a mechanical deformation effect of tension-compression uniform expansion. The tension-compression uniform expansion vascular stent structure is made of a degradable material, and the tension-compression uniform expansion vascular stent structure not only has a mechanical deformation effect of tension-compression uniform expansion but also can degrade in vivo. The inner concave structure includes a T-shaped rod and an inclined rod; the horizontal part of the T-shaped rod is located outside the hexagonal honeycomb structure; after the vertical part of the T-shaped rod is inserted from the gap, the vertices are respectively connected to the sides of the hexagonal honeycomb structure through two inclined rods.

2. The degradable vascular stent with both tensile and compressive uniform expansion performance according to claim 1, wherein The number of the tension-compression uniform expansion basic structural units arranged circumferentially along the vascular stent is 4 to 8.

3. The degradable vascular stent with uniform tensile and compressive expansion performance according to claim 1, wherein The number of the tension-compression uniform expansion basic structural units arranged axially along the vascular stent is greater than 2.

4. The degradable vascular stent with both tensile and compressive uniform expansion performance according to claim 1, characterized in that, The degradable material is a metal material, a polymer material or a metal-polymer composite material.

5. The degradable vascular stent with both tensile and compressive uniform expansion performance according to claim 4, wherein The metal material is magnesium and its alloys, iron and its alloys, zinc and its alloys; the polymer material is polylactic acid, polyglycolic acid, polycaprolactone.

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