CN111513900A

CN111513900A - Novel auxetic degradable vascular stent structure based on wave configuration

Info

Publication number: CN111513900A
Application number: CN202010256785.4A
Authority: CN
Inventors: 王丽珍; 袁慧静; 樊瑜波; 高元明
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2020-04-02
Filing date: 2020-04-02
Publication date: 2020-08-11
Anticipated expiration: 2040-04-02
Also published as: CN111513900B

Abstract

The invention provides a novel auxetic degradable vascular stent structure based on a wave configuration, which is formed by arranging and connecting large cell structures along the axial direction and the circumferential direction of a stent; each large cell structure further comprises four small cell structures; two small cell structures adjacent along the circumferential direction are arranged in a mirror image mode relative to a symmetrical axis in the axial direction; two small cell structures adjacent along the axial direction of the bracket are arranged in a mirror image mode relative to a symmetrical axis in the radial direction; each small cell structure is formed by intersecting two equilong wavy lines at the middle position, and each wavy line comprises n first circular arcs which are sequentially connected; at least one second arc is arranged at two ends of the n first arcs which are sequentially connected, and the radius of the second arc is larger than that of the first arc. The vascular stent structure has the characteristic of auxetic expansion, is matched with the characteristic that the length of a blood vessel is increased while the inner diameter of the blood vessel is enlarged, can effectively avoid the uneven degradation of the stent, and prevents the fracture of the stent after the stent is placed into a human body.

Description

Novel auxetic degradable vascular stent structure based on wave configuration

Technical Field

The invention relates to the field of medical instruments, in particular to a novel auxetic degradable vascular stent structure based on a wave configuration.

Background

The morbidity and mortality of cardiovascular diseases of residents in China are increased year by year, and according to a report 2018 on cardiovascular diseases in China issued by the research center for cardiovascular disease control of the Ministry of health, the number of people suffering from cardiovascular diseases in China is 2.9 hundred million at present, and the number of people suffering from cardiovascular diseases accounts for 50 percent of the number of people suffering from cardiovascular diseases in the whole world in 2020, which is estimated to reach 2500 million people per year.

Currently, for cardiovascular diseases, interventional therapy is the most common treatment method, and is also the preferred treatment method for patients because of the advantages of no need of thoracotomy, short operation time and quick postoperative recovery. The interventional therapy technique is to insert a medical device into a heart, a blood vessel, or the like to perform a therapy. The blood vessel support is an important medical appliance used in interventional therapy, and can be placed into a blood vessel of a lesion section, so that the purpose of keeping the blood flow in the blood vessel smooth can be achieved. Since the appearance and development of the vascular stent in the 80 th century till now, the vascular stent is sequentially subjected to the research and development processes of a metal bare stent, a non-degradable drug eluting stent, a degradable stent and a degradable drug eluting stent. Among them, the undegradable vascular stent remains permanently in the body and becomes a "foreign body" in the body, and in order to prevent complications thereof, patients need to take antiplatelet drugs for a long period of time. The degradable blood vessel stent is gradually degraded and absorbed after being placed into a human body to complete blood vessel remodeling, so that side effects caused by long-term administration of drugs are avoided, and the degradable blood vessel stent gradually becomes a focus of attention in the field compared with a traditional stent.

However, the degradable vascular stent in the prior art still has the following technical problems: on one hand, the stress concentration effect generated after the stent is placed into a human body and is propped open can cause the stent to be degraded unevenly, so that the phenomenon that a stress concentration area is easy to break can occur when the stent is used, the service life of the stent is further influenced, and the stent can lose efficacy before the function of blood vessel remodeling is completed; on the other hand, the blood vessel has the property of negative poisson ratio, and can be correspondingly expanded in the axial direction when the blood vessel is radially expanded, namely, the blood vessel has the auxetic characteristic, most of the common stents in the market at present are positive poisson ratio structures and are not matched with the negative poisson ratio characteristic of the blood vessel, so that the problems of inaccurate positioning, dog bone effect and the like can be caused after the stent is placed in the blood vessel. In this case, to improve the performance of the degradable scaffold, the above-mentioned two problems must be solved. However, the problem to be solved by those skilled in the art is how to find a vessel stent with negative poisson ratio, which can slow down the stress concentration phenomenon and prevent the rupture failure after implantation.

Disclosure of Invention

The application solves the technical problems that the blood vessel stent in the prior art is easy to be unevenly degraded under the stress concentration effect, so that the blood vessel stent is broken and fails, and the negative Poisson ratio characteristic of the blood vessel is not matched, and then the novel auxetic degradable blood vessel stent structure based on the wave configuration, which can effectively slow down the stress concentration, realize the even degradation and has the negative Poisson ratio characteristic, is provided.

The technical scheme adopted by the application for solving the technical problems is as follows:

a novel tension-expansion degradable vascular stent structure based on a wave configuration is formed by arranging and connecting large cell structures along the axial direction and the circumferential direction of a stent; each large cell structure consists of four small cell structures; two adjacent small cell structures along the circumferential direction are arranged in a mirror image mode relative to the symmetrical plane of the axial direction; two adjacent small cell structures along the axial direction of the bracket are arranged in a mirror image mode relative to the symmetrical plane of the radial direction; each small cell structure is formed by intersecting two wave lines with equal length at the middle position, each wave line comprises n first circular arcs which are sequentially connected and have the equal radius of r, wherein n is more than or equal to 2 and is an even number; at least one second arc with the radius R is arranged at two ends of the n first arcs which are sequentially connected, and the radius R of the second arc is larger than the radius R of the first arc; in the first circular arc and the second circular arc which are positioned on a wavy line, the opening directions of every two adjacent circular arcs are opposite and are connected in a tangent mode; when the small cell structure is tiled and unfolded to a plane, tangent connection points of adjacent first circular arcs of each wave line on the small cell structure are located on the same middle line, and the middle lines of the two wave lines are symmetrically arranged relative to the plane passing through the radial direction and the connection points of the wave lines.

The two ends of each wavy line are also provided with third circular arcs with equal radiuses, and the third circular arcs are connected with one ends, far away from the first circular arcs, of the second circular arcs; and two adjacent small cell structures are connected through a pair of third arcs, and the radius of each third arc is smaller than the radius R of each second arc.

The two wavy lines of each small cell structure are arranged in a geometrical mode that the wavy lines can rotate around the intersection point to coincide.

A pair of the third arcs at the joint of two adjacent small cell structures along the circumferential direction are connected in a tangent mode, and the tangent line of the joint is parallel to the radial plane of the blood vessel support; and a pair of third arcs at the joint of two adjacent small cell structures along the axial direction of the stent are connected in a tangent mode, and the tangent of the joint is parallel to the axial direction of the blood vessel stent.

In the two wavy lines of each small cell structure, two ends of one wavy line are respectively connected with two small cell structures adjacent in the axial direction; two ends of the other wavy line are respectively connected with two small cell structures adjacent in the circumferential direction.

Each wavy line comprises 6 first arcs which are connected in sequence; the two ends of the 6 first arcs connected in sequence are respectively provided with one second arc, and one end, far away from the first arcs, of each second arc is connected with one third arc.

The radius r of the first arc is 0.17mm-0.21 mm; the radius R of the second arc is 0.2mm-0.25 mm; the radius of the third arc is 0.16mm-0.2 mm.

The large cell structures in a row are sequentially arranged and connected along the circumferential direction to form a supporting ring structure of the support, the large cell structures in a row are sequentially arranged and connected along the axial direction of the support to form a connecting rod structure of the support, and one supporting ring structure consists of 2-4 large cell structures.

When the small cell structures are flatly laid and unfolded to a plane, the included angle between the middle line of each wavy line of the small cell structures and the radial plane of the vascular stent is 30-45 degrees.

The central angle range of the first arc is 45-150 degrees; the central angle range of the second arc is 45-150 degrees; the central angle of the third arc ranges from 30 to 60 degrees.

The novel auxetic degradable vascular stent structure based on the wave configuration has the advantages that:

the novel auxetic degradable vascular stent structure based on the wave configuration is provided with large cell structures, the large cell structures are sequentially arranged and connected along the circumferential direction to form a supporting ring structure of the stent, and the large cell structures are sequentially arranged and connected along the axial direction of the stent to form a connecting rod structure of the stent; the large cell structure is composed of four small cell structures, two adjacent small cell structures are arranged in a mirror image mode, and each small cell structure comprises two crossed wavy lines. This kind of mode of setting up makes when will through the sacculus mode when blood vessel support arranges in the blood vessel, the sacculus struts the support, the support ring structure of support can be at the radial expansion of support, the connecting rod structure of support also can take place the extension in the axial simultaneously, make the support at radial inflation and simultaneously, axial length also is greater than original length, and then realize the auxetic characteristic, with the blood vessel internal diameter at the characteristic phase-match that the blood vessel length also can increase of expansion, it fixes a position in the blood vessel to change in, also avoided the support to take place the axial to shorten when the sacculus expansion, produce the problem of "dog bone effect".

The intravascular stent comprises two wavy lines forming a small cell structure, wherein each wavy line comprises n first circular arcs which are sequentially connected and have the same radius of R, two ends of each first circular arc which are sequentially connected are respectively provided with at least one second circular arc with the radius of R, and the radius of R of each second circular arc is larger than the radius of R of each first circular arc; and in the first circular arc and the second circular arc which are positioned on a wavy line, the opening directions of every two adjacent circular arcs are opposite and are connected in a tangent mode. In the two processes of pressing and holding the bracket on the saccule and supporting the bracket by the saccule, n first arcs with radius r can generate elastic deformation to play a role in effectively dispersing the bracket pressure, and then a second arc with larger radius is arranged at the end part, and the second arc can generate large plastic deformation in the processes of pressing and holding and supporting the bracket, so that the stress concentration at the end part is avoided, and the problems of uneven degradation, breakage and the like of the bracket caused by the stress concentration in the degradation process are avoided. As a preferred embodiment, the number n of the first arcs is set to 6, that is, each wavy line includes 6 first arcs connected in sequence, so that the first arcs can achieve a proper partial pressure effect, and unnecessary stress concentration caused by an excessive number of the arcs is also avoided.

According to the invention, preferably, the two ends of each wavy line are also provided with third circular arcs with equal radiuses, and the third circular arcs are connected with one ends of the second circular arcs far away from the first circular arcs; and two adjacent small cell structures are connected through a pair of third arcs, and the radius of each third arc is smaller than the radius R of each second arc. A pair of the third arcs at the joint of two adjacent small cell structures along the circumferential direction are connected in a tangent mode, and the tangent line of the joint is parallel to the radial plane of the blood vessel support; and a pair of third arcs at the joint of two adjacent small cell structures along the axial direction of the stent are connected in a tangent mode, and the tangent of the joint is parallel to the axial direction of the blood vessel stent. The third arc is arranged to realize the connection of the small cell structure, and the advantages are that: the pair of third arcs is used for connecting the second arcs of the small cell structures with the opening directions of the two arcs opposite to the opening direction of the third arc, so that the stress at the stress concentration part of the common bracket can be dispersed to the second arcs of the two small cell structures, and the partial pressure effect is achieved.

In the preferred vascular stent of the present invention, one of the support ring structures is composed of 2-4 of the macro-cellular structures, so as to be suitable for being placed in blood vessels with different inner diameters.

In order to make the technical scheme of the novel auxetic degradable vascular stent structure based on the wavy configuration more clearly understood, the present invention is further described with reference to the accompanying drawings and the specific embodiments.

Drawings

Fig. 1 is a schematic view showing the partial deployment of the auxetic and degradable vascular stent structure based on the wave configuration according to the present invention.

FIG. 2 is a schematic structural diagram of the striped microcell structure according to the present invention.

FIG. 3 is a schematic structural diagram of the striped microcell structure according to the present invention.

Fig. 4 is a schematic view of a striped large cell structure according to the present invention.

Fig. 5 is a schematic diagram of a macro cell structure according to the present invention.

FIG. 6 is a side view of the novel auxetic and degradable vascular stent structure based on a wavy configuration according to the present invention;

FIG. 7 is a perspective view of the novel structure of the auxetic degradable blood vessel stent based on the wave configuration according to the present invention;

wherein the reference numerals are:

1-a first arc; 2-a second arc; 3-third arc.

Detailed Description

The embodiment provides a novel auxetic degradable vascular stent structure based on a wave configuration, and the vascular stent structure is made of magnesium alloy materials. As shown in fig. 1, the vascular stent structure is formed by arranging and connecting large cell structures B along the axial direction and the circumferential direction of the stent; in this embodiment, one row of the macro cell structures B are sequentially arranged and connected in the circumferential direction to form a support ring structure C of the support, and one row of the macro cell structures B are sequentially arranged and connected in the axial direction of the support to form a connecting rod structure D of the support. Each large cell structure B consists of four small cell structures A; two adjacent small cell structures along the circumferential direction are arranged in a mirror image mode relative to a symmetrical plane passing through the axial direction and a connection point of the small cell structures; two adjacent small cell structures along the axial direction of the stent are arranged in a mirror image mode relative to a symmetrical plane passing through the radial direction and the connection point of the small cell structures.

As shown in fig. 2 and fig. 3, each of the small cell structures a is formed by two wave lines of equal length intersecting at an intermediate position, each of the wave lines includes n first arcs with equal radius r connected in sequence, where n is preferably 6 in this embodiment, that is, each of the wave lines includes 6 first arcs connected in sequence; as an alternative embodiment, n may be set to 2 or more and n is an even number; two ends of the n first arcs which are sequentially connected are respectively provided with a second arc with the radius R, and the radius R of the second arc is larger than the radius R of the first arc; in this embodiment, the radius R of the first arc is 0.17mm, and the radius R of the second arc is 0.2 mm. As a preferred embodiment, the radius r of the first circular arc may be set to 0.17mm to 0.21 mm; the radius R of the second circular arc can be set to be 0.2mm-0.25mm, and the central angles of the first circular arc and the second circular arc are both smaller than 180 degrees. Also as a preferred embodiment, the central angle of the first arc ranges from 45 to 150 °; the central angle of the second arc ranges from 45 to 150 degrees.

The outline of the blood vessel support is cylindrical, so that the large cell structure B and the small cell structure A of the blood vessel support are distributed on the surface of the side wall of the cylindrical outline, as shown in fig. 2, when the small cell structures are tiled and unfolded to a plane, namely the support is tiled in situ into a rectangular plane after being cut off axially, the tangent connection points of the adjacent first arcs of each wavy line of the small cell structures are positioned on the same middle line. The middle line of the two wavy lines is symmetrically arranged relative to a plane passing through the radial direction and the connecting point of the wavy lines. When the microcell structure is laid and unfolded on a plane, an included angle θ/2 between a middle line of each wave line of the microcell structure and a radial plane of the vascular stent in this embodiment is 45 °, and an included angle θ between middle lines of two wave lines is 90 °. As a preferred embodiment, an included angle between a middle line of each wavy line of the small cell structure and a radial plane of the vascular stent can be set to be 30-45 degrees, so that the stent has excellent stretching and expanding performance in the radial direction and the axial direction, and uniform stress of the stent in the processes of stretching and pressing and holding is facilitated.

As shown in fig. 2 and 3, in the first circular arc and the second circular arc which are located on a wavy line, the opening directions of every two adjacent circular arcs are opposite and are connected in a tangential manner. The openings of the first circular arc and the second circular arc are arch-shaped openings formed by intersecting the middle line or the extension line of the middle line and the circular arcs.

In this embodiment, both ends of each wavy line are further provided with third arcs with equal radius, and the third arcs are connected with one ends of the second arcs far away from the first arcs; two adjacent small cell structures are connected through a pair of the third arcs. In this embodiment, the radius of the third circular arc is 0.16mm, and as a preferred embodiment, the radius of the third circular arc may be set to 0.16-0.2mm, the central angle of the third circular arc is less than 90 °, and the central angle of the third circular arc is preferably in the range of 30-60 °.

The two wave lines of each small cell structure are arranged in a geometrical manner which can be rotated to coincide around the intersection point, i.e. if one of the two wave lines is rotated along the intersection point, it can coincide with the other wave line when rotated to the position of the wave line. In the two wavy lines of each small cell structure, two ends of one wavy line are respectively connected with two small cell structures adjacent in the axial direction; two ends of the other wavy line are respectively connected with two small cell structures adjacent in the circumferential direction. A pair of the third arcs at the joint of two adjacent small cell structures along the circumferential direction are connected in a tangent mode, and the tangent line of the joint is parallel to the radial direction of the blood vessel support; and a pair of third arcs at the joint of two adjacent small cell structures along the axial direction of the stent are connected in a tangent mode, and the tangent of the joint is parallel to the axial direction of the blood vessel stent. As shown in fig. 2, the opening direction of the arcuate opening formed by the intersection of the second arc and the middle line of the wavy line is opposite to that of the first arc adjacent to the second arc, but in order to ensure that a pair of third arcs at the connection of two adjacent cell structures a are connected in a tangent manner, the angle of the second arc is larger than that of the arcuate opening, that is, the second arc continues to extend from the connection point with the first arc to the extension line of the middle line until the second arc is tangent to the third arc. In this embodiment, one second arc is arranged at one end of each wavy line, but the practical application is not limited to this, and more than two second arcs may be arranged, and the number of the second arcs respectively located at the two ends of each wavy line should be the same; when more than two second arcs are arranged, the opening directions of the two adjacent second arcs are opposite; and the angle of one second circular arc positioned at the outermost end, namely the end far away from the first circular arc is larger than the angle of the arched opening, so that the tangential connection with the third circular arc is realized, and the angles of the other second circular arcs are equal to the angle of the arched opening formed by the second circular arc and the extension line of the middle line. When the stent is unfolded or pressed, the second circular arcs are subjected to plastic deformation, preferably, the number of the second circular arcs at each end of the wavy line is not too large, preferably one, and then the effect of sufficient partial pressure and plastic deformation can be achieved.

Referring to fig. 4 and 5, which are schematic diagrams of the macro-cell structure in the structure of the present invention, the macro-cell structure is obtained by first forming a first structure by mirroring the small cell structure in the circumferential direction relative to the axial plane, and then mirroring the first structure in the axial direction relative to the radial plane. The large cell structure is the smallest basic unit structure of the present invention.

As shown in fig. 6 and 7, in the present embodiment, 3 macro cell structures B are sequentially arranged and connected in a circumferential direction to form one support ring structure C of the stent, and as an alternative embodiment, one support ring structure is preferably composed of 2 to 4 macro cell structures. According to practical requirements, the length and the diameter of the support structure can be adjusted by setting the number of the macro cell structures B arranged in the axial direction and the number of the macro cell structures B arranged in the circumferential direction. In this embodiment the intravascular stent has an inner diameter of 0.3mm and a stent wall thickness of 0.145mm in the radial direction. As a preferred embodiment, the thickness of the wall of the bracket is preferably set to 0.12-0.15mm, so that the metal bracket has a good supporting effect.

The invention provides the structure of the pull-expansion degradable vascular stent based on the wave configuration, which enables the stress distribution of the stent to be uniform when the stent is expanded, solves the problem of uneven degradation caused by stress concentration when the degradable stent is degraded, and has the pull-expansion characteristic to enable the stent to be accurately positioned.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the claims.

Claims

1. A novel structure of a novel tensile-expansion degradable blood vessel stent based on a wave configuration is characterized in that the novel structure is formed by arranging and connecting large cell structures along the axial direction and the circumferential direction of the stent; each large cell structure consists of four small cell structures;

two adjacent small cell structures along the circumferential direction are arranged in a mirror image mode relative to the symmetrical plane of the axial direction; two adjacent small cell structures along the axial direction of the bracket are arranged in a mirror image mode relative to the symmetrical plane of the radial direction;

each small cell structure is formed by intersecting two wave lines with equal length at the middle position, each wave line comprises n first circular arcs which are sequentially connected and have the equal radius of r, wherein n is more than or equal to 2 and is an even number; at least one second arc with the radius R is arranged at two ends of the n first arcs which are sequentially connected, and the radius R of the second arc is larger than the radius R of the first arc; in the first circular arc and the second circular arc which are positioned on a wavy line, the opening directions of every two adjacent circular arcs are opposite and are connected in a tangent mode;

when the small cell structure is tiled and unfolded to a plane, tangent connection points of adjacent first circular arcs of each wave line on the small cell structure are located on the same middle line, and the middle lines of the two wave lines are symmetrically arranged relative to the plane passing through the radial direction and the connection points of the wave lines.

2. The novel auxetic and degradable vascular stent structure according to claim 1, wherein both ends of each of the wavy lines are further provided with a third arc with equal radius, and the third arc is connected with one end of the second arc away from the first arc; and two adjacent small cell structures are connected through a pair of third arcs, and the radius of each third arc is smaller than the radius R of each second arc.

3. The novel auxetic and degradable vascular stent structure according to claim 1 or 2, wherein the two wavy lines of each of the small cell structures are arranged in a geometrical manner that can be rotated and coincided around the intersection point.

4. The novel auxetic and degradable vascular stent structure according to claim 3, wherein a pair of the third arcs at the junctions of two of the cell structures adjacent in the circumferential direction are connected in a tangent manner, and the tangent of the junctions is parallel to the radial plane of the vascular stent; and a pair of third arcs at the joint of two adjacent small cell structures along the axial direction of the stent are connected in a tangent mode, and the tangent of the joint is parallel to the axial direction of the blood vessel stent.

5. The novel auxetic and degradable vascular stent structure according to claim 4, wherein two ends of one of the two wavy lines of each of the small cell structures are respectively connected to two small cell structures adjacent in the axial direction; two ends of the other wavy line are respectively connected with two small cell structures adjacent in the circumferential direction.

6. The novel auxetic, degradable vascular stent structure according to claim 5, wherein each of the wavy lines comprises 6 first circular arcs connected in sequence; the two ends of the 6 first arcs connected in sequence are respectively provided with one second arc, and one end, far away from the first arcs, of each second arc is connected with one third arc.

7. The novel auxetic degradable vascular stent structure according to claim 6, wherein the radius r of the first circular arc is 0.17mm-0.21 mm; the radius R of the second arc is 0.2mm-0.25 mm; the radius of the third arc is 0.16mm-0.2 mm.

8. The novel structure of claim 7, wherein a row of said macro-cellular structures are sequentially arranged along the circumferential direction to form a support ring structure of the stent, a row of said macro-cellular structures are sequentially arranged along the axial direction of the stent to form a connecting rod structure of the stent, and a single said support ring structure is composed of 2-4 said macro-cellular structures.

9. The novel auxetic and degradable vascular stent structure according to claim 8, wherein when the small cell structures are laid out flat on a plane, an included angle between a middle line of each wave line of the small cell structures and a radial plane of the vascular stent is 30-45 °.

10. The novel auxetic degradable vascular stent structure according to any of claims 1 to 9, wherein the central angle of the first circular arc ranges from 45 ° to 150 °; the central angle range of the second arc is 45-150 degrees; the central angle of the third arc ranges from 30 to 60 degrees.