CN113413256B

CN113413256B - Self-expanding stent

Info

Publication number: CN113413256B
Application number: CN202110777379.7A
Authority: CN
Inventors: 汪泽辉; 陈奕龙
Original assignee: Shenzhen Kyd Biomedical Technology Co ltd
Current assignee: Shenzhen Kyd Biomedical Technology Co ltd
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2023-06-02
Anticipated expiration: 2039-01-31
Also published as: CN109662819A; CN109662819B; CN113413256A

Abstract

The invention relates to the technical field of medical instruments for interventional procedures, and particularly discloses a self-expanding stent suitable for supporting a narrow lumen, and a preparation method and application thereof. The invention can solve the technical problem that the performance of the stent in the prior art can not completely meet the implantation of the iliac veins, has higher safety, and is particularly suitable for the treatment of the iliac vein stenosis.

Description

Self-expanding stent

The application is a divisional application with the original application number 2019100963223 and the name of self-expanding stent and a preparation method and application thereof, and the application date of the original application is 2019, 01, 31.

Technical Field

The invention relates to the technical field of medical instruments for interventional procedures, in particular to a self-expanding bracket suitable for supporting a narrow lumen, and a preparation method and application thereof.

Background

The stent is used for being placed in a lesion section of the lumen so as to support the lumen of the narrow occlusion section and keep the lumen unobstructed. Such as vascular stents, are typically used to be placed in a diseased portion of a vessel to support a stenosed vessel, reduce elastic recoil and reshaping of the vessel, and maintain patency of lumen blood flow. Due to differences in vascular physiology in different parts of the human body, specialized stents have been developed for different vascular lesions, and stents of different indications are often not used instead. At present, a plurality of blood vessel support type stents, including coronary stents, peripheral arterial stents and the like are researched and applied, and a plurality of mature products are marketed.

The clinically common causes of the vein stenosis include Cockett syndrome, postthrombotic syndrome (Postthrombotic Syndrome, PTS), tumor compression and the like. The most important of these is the Cockett syndrome, also called iliac vein compression syndrome, which refers to the mechanical action generated by long-term compression of the left iliac total vein at the junction of the lower vena cava crossing from the front and the pulsation thereof and the compression of the rear fifth lumbar vertebra, which leads to the hyperplasia of the left iliac total vein to form acanthosis, intra-cavity adhesion, lumen stenosis or occlusion and other changes, thereby leading to the obstruction of the return flow of the iliac vein, and the consequences of deep vein thrombosis of lower limbs, varicose veins, pigment deposition, lower limb erosion and the like.

Implantation of a stent in the left total iliac vein lesion by interventional surgery is the first choice for treatment of the Cockett syndrome. However, vascular stents suitable for the iliac veins, particularly the left common iliac vein, are currently not commercially available in mature form, and are used clinically in place of other types of stents. Typically, such as the Wallstent venous stent produced by boston science, and the E-luminaexx peripheral arterial stent produced by the more commonly used bard corporation, none of the above stents, however, are developed for the physiological anatomy of the iliac vein, are still inadequate for application to the iliac vein, and can be potentially risky.

The ideal iliac vein stent has the characteristics that:

1. compared with the common vein or arterial vessel stenosis, which is the deposition of embolism or hyperplasia of blood vessel inner wall, the stenosis lesion of the left common iliac vein of the Cockett syndrome occurs mainly due to the physical compression of the artery and the fifth lumbar vertebra and the intravascular fibrous adhesion caused by the physical compression, thus the stent is required to have stronger supporting performance;

2. the iliac veins are closely attached to the pelvis to walk, the physiological structure is more curved, and the support is required to have excellent flexibility;

3. the stenotic lesion of the left common iliac vein is usually close to the opening which is converged into the inferior vena cava, and in order to avoid that the stent cannot completely cover the stenotic lesion due to shrinkage or drifting after the stent is released, the two ends of the stent are required to exceed the lesion respectively when the stent is released in a blood vessel, the distal end of the stent stretches into the inferior vena cava, and the distal end of the stent can interfere with contralateral blood flow, and researches report that the stent stretches into the inferior vena cava too much after being implanted into the left common iliac vein to cause the potential risk of contralateral thrombus to increase, so that the stent can completely cover the stenotic lesion, and simultaneously, the least stent stretches into the inferior vena cava is hoped;

4. the opening of the left common iliac vein which is converged into the inferior vena cava is horn-shaped, the distal end of the bracket is difficult to position at the opening, and the bracket is easy to jump forward when released, so that the bracket is released and positioned inaccurately.

The braided stent represented by the Wallstent is a reticular stent braided by alloy wires, the alloy wires are staggered to form a closed diamond-shaped mesh, and the alloy wires staggered at the mesh are not physically connected, so that the stent has very excellent flexibility and vascular adaptability, but the stent has weaker supporting performance, inaccurate positioning and short length, and the left common iliac vein implanted in clinical operation needs to be stretched into the inferior vena cava too much.

The E-luminanex stent is used as a hollowed-out stent formed by cutting a metal tube, the periphery of the stent consists of a plurality of groups of annular wavy rods which are axially arranged in parallel and connecting rods for connecting adjacent wavy rods, and staggered rods which enclose hollowed-out holes are integrally connected, so that the stent has more excellent supporting performance, but insufficient fracture resistance, and has insufficient adaptability to a bent blood vessel, the left common iliac vein still needs to be implanted into the inferior vena cava in clinical operation, and the stent is positioned at the opening of the left common iliac vein by utilizing the inclination of the part extending into the inferior vena cava to the inner wall of the inferior vena cava.

A stent having a spiral pattern cut from a metal tube different from the foregoing two types of stents has been proposed, which has excellent torsional flexibility. For example, chinese publication CN108670511A, CN108371572A, CN103784222A, CN203662949U, CN103313681A, CN106137479a, US publication US20040044401A, US20130338759a, PCT publication WO2012018844A, etc., disclose various stents having single-helix support structures, respectively. In addition, chinese publication CN108348345 a discloses a stent with a double helix support structure.

The stent disclosed in the foregoing patent has a uniform single spiral or double spiral as a supporting structure, and the single spiral or double spiral is provided with a wave structure, and the enhanced supporting performance can be obtained to a certain extent by increasing the number of waves. However, the contradiction between different structures and performance requirements of the stent at different parts of the iliac vein can not be solved, and the technical problem that the stent needs to extend into the inferior vena cava can not be overcome.

Thus, there is a need to develop new structural and performance stents, particularly stents suitable for use in the iliac veins.

Disclosure of Invention

The invention firstly provides a self-expanding stent, which can solve the technical problem that the stent in the prior art cannot meet the application requirements of special lumens such as ilium veins and the like.

The technical scheme adopted by the invention is as follows:

a self-expanding stent comprises two different types of spiral sections which are formed into a hollow tube shape and are arranged along the axial direction of the hollow tube shape, wherein a first spiral section comprises a single spiral line, and a second spiral section comprises a double spiral line formed by two parallel spiral lines;

the single spiral line and the double spiral line extend in the same direction and in a circumferential shape around the central axis of the tube shape, and one end of each of the adjacent single spiral line and the adjacent double spiral line is combined into a single spiral line in a transition area between the two, and the single spiral line and the double spiral line are respectively closed in other transition areas along the circumferential direction of the tube shape to form a closed ring without a free end.

Wherein the lead angle of the single spiral line is not larger than the lead angle of the double spiral line; the spiral line is formed by a spiral wave-shaped rod, and the wave-shaped rod is provided with a wave-shaped structure which is distributed along the length direction of the wave-shaped rod.

The waveforms of the front spiral turn and the rear spiral turn of the single spiral line are staggered in the circumferential direction of the pipe, and the waveforms of the front spiral turn and the rear spiral turn of the double spiral line are arranged in parallel in the circumferential direction of the pipe.

And, adjacent line turns of the single spiral line are connected by the crest and trough that the distance is closest by the first connecting component, any spiral line in the double spiral line and adjacent spiral line connect two crest or two trough that the distance is closest by the second connecting component;

the first connecting part and the second connecting part are distributed along the circumferential direction of the tubular shape.

Further, the self-expanding stent further comprises a non-helical section, the non-helical section comprises an inclined ring surrounding the central axis of the tube shape, the inclined ring is composed of an annular wavy rod, and the inclined ring and a closed ring of a single helical line in the first helical section are jointly biased to one side of the radial section of the tube shape;

the inclined rings and the closed ring waveforms of the first spiral section are staggered in the circumferential direction of the pipe shape, and the wave crests and wave troughs which are closest to the inclined rings and the closed ring waveforms of the first spiral section are connected through the first connecting part.

Preferably, the wave form of the wave form rod is a Z-shaped wave, the wave height of the wave form rod is 1-5 mm, the wave form rod is provided with 10-25 wave crests or 10-25 wave troughs on each 360-degree spiral turn, and the number of the first connecting part and the second connecting part distributed along the circumferential direction of the tube shape is 3-8 respectively;

the width of the rod body of the wave-shaped rod is larger than that of the first connecting part and the second connecting part, the width of the rod body of the wave-shaped rod is 0.1-0.4 mm, the width of the first connecting part is 0.2-0.5 mm, and the width of the second connecting part is 0.1-0.3 mm;

the length of the first connecting part along the axial direction of the bracket is not more than 2mm;

the length of the second connecting part along the axial direction of the bracket is larger than the wave height of the wave rod, and the difference value between the length and the wave height is not larger than 2mm.

In a preferred embodiment, the first connecting part is angled with respect to the axial direction of the holder, and the second connecting part is substantially parallel with respect to the axial direction of the holder.

Optionally, the two wavy bars of the double spiral line are combined into a wavy bar in the transition area of the other end of the wavy bar, and then a closed loop without a free end is formed.

In a preferred embodiment, in the transition zone, one wave-shaped bar, which is composed of two wave-shaped bars, has a tendency to decrease in height and in width in the circumferential direction of the stent.

Optionally, the length of the first helical segment is less than the length of the second helical segment; the total length of the support is 50-120 mm, the sum of the lengths of the non-spiral section and the first spiral section is 10-60 mm, and the length of the double-spiral section is 30-100 mm.

The self-expanding stent may be straight or tapered in diameter, wherein in an alternative embodiment the self-expanding stent is monotonically tapered in its axial direction in the unconstrained free expanded state and the diameter of the first helical segment is generally greater than the diameter of the second helical segment.

In a preferred embodiment, adjacent first connecting parts in a single spiral line are arranged in a staggered manner along the axial direction of the bracket, and adjacent second connecting parts in a double spiral line are arranged in parallel.

Alternatively, the first connecting member and the second connecting member are linear or arcuate or S-shaped or dumbbell-shaped.

The invention also provides application of the self-expanding stent as an iliac vein stent.

The invention also provides a preparation method of the self-expanding stent, which comprises the steps of cutting a tube material by using laser and removing redundant parts of the tube material to obtain a hollow tubular structure with a waveform rod and a connecting part integrated, wherein the tube material is made of a shape memory material.

The self-expanding stent adopts a supporting structure of a single spiral section and a double spiral section which are simultaneously designed on the single stent, and connecting parts with different structures are designed on the single spiral section and the double spiral section along the circumferential direction, so that the stent has different flexibility and extrusion resistance on the two sections, the single spiral section has better extrusion resistance relative to the double spiral section, can well support a narrow lumen, the double spiral section has better flexibility relative to the single spiral section, can fully adapt to the lumen section with complex bending, and can better adapt to the shape of a blood vessel and realize better wall attaching performance.

The self-expanding stent can be further provided with an annular supporting structure at the front side of the single spiral section, so that the extrusion resistance and the anchoring capacity of the stent at the front end are further enhanced, and the occurrence rate of forward jump of the release of the stent is reduced. And when the front end of the support needs to be designed into a bevel connection, the annular supporting structure is an inclined ring, and the support can obtain a required bevel connection angle without influencing the setting of the lift angle of the single spiral section through the adjustment of the waveform size of the inclined ring along the circumferential direction.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic view of a self-expanding stent embodiment of the present invention;

FIG. 2 is a schematic view of the self-expanding stent embodiment of FIG. 1 rotated about its central axis by a certain angle;

FIG. 3 is a schematic view of the self-expanding stent embodiment of FIG. 1 rotated another angle along its central axis;

FIG. 4 is a plan expanded view of the embodiment of the self-expanding stent of FIG. 1, wherein the A, B portion is a segment of a wavy rod that self-closes and forms a closed loop, respectively;

FIG. 5 is a cut-line plan-out schematic view of the raw tubing of the self-expanding stent embodiment of FIG. 1;

fig. 6 is an enlarged schematic view of the first connecting member;

FIG. 7 is an enlarged schematic view of a second connection member;

FIG. 8 is a schematic view of the embodiment of FIG. 1 with the self-expanding stent in place in the left common iliac vein;

FIG. 9 is an X-ray image of a self-expanding stent of an embodiment of the present invention placed in the left common iliac vein of an experimental rabbit, wherein the left image A is a partial release of the front end of the stent and the right image B is a complete release of the stent;

FIG. 10 is a test fixture for radial support force of a bracket;

fig. 11 is an anatomic photograph of a self-expanding stent placed in the left common iliac vein of an experimental rabbit showing the vessel and stent cut apart in the axial direction, in accordance with one embodiment of the present invention.

It should be noted that fig. 1-3 hide the structure of the stent on the opposite side of the viewing direction of the view in order to clearly show the structure of the stent in the illustrated embodiment.

In the drawings, reference numerals are described as follows:

100. a first helical segment; 200. a transition region between the first helical segment and the second helical segment; 300. a second helical segment; 400. a diagonal ring;

110. a transition region at the other end of the first helical segment; 310. a transition region at the other end of the second helical segment;

610. a first connecting member; 620. and a second connection member.

201 and 202 are respectively the upper and lower ends of the transition zone shown as 200 along the circumferential direction of the bracket;

311 is the area where the two wavy bars of the double helix in the transition area shown by 310 are combined into one wavy bar; 312 is the area where the segment B is merged with one of the wavy bars obtained after merging in the transition area indicated at 310; 313. a closed loop with no free ends in the transition region shown at 310;

511. 512, 513, 514 are four X-ray opaque material markers disposed at the front elliptical bezel of the stent, respectively, wherein 511 and 513 are located at the two endpoints of the elliptical major axis of the bezel and 512 and 514 are located at the two endpoints of the elliptical minor axis of the bezel;

521. 522 are two X-ray opaque material markers, respectively, disposed at the rear circular stand of the stent, and 521 and 522 are located at the two ends of one diameter of the circle of the straight tube orifice.

In fig. 8, 1 is a self-expanding stent, 701 is the inferior vena cava, 702 is the left common iliac vein, 703 is the right common iliac vein, 704 is the right common iliac artery.

Detailed Description

The invention is described in further detail below with reference to the drawings and the detailed description.

Self-expanding stent

Example 1

The present embodiment provides a self-expanding stent having two different types of helical segments arranged in the axial direction thereof forming a hollow tube shape, wherein the first helical segment comprises a single helix and the second helical segment comprises a double helix of two parallel helices. Referring to fig. 1-3, 100 and 300 illustrate a first helical segment comprising a single helix and a second helical segment comprising two parallel double helices, respectively.

Specifically, in the transition region between the first spiral section and the second spiral section in this embodiment, referring to fig. 1, the region 200 shows the structure of the transition region, two waveform rods forming a double spiral line are combined from the end 201 to the end 202 into one waveform rod, the wave height of the first waveform of the waveform rod is equal to or similar to the sum of the wave heights of the two waveform rods at the upper end of the waveform rod, and the wave height of the waveform in the direction of the end 202 is gradually reduced until approaching and extending to the waveform rod of the first spiral section. The 200-region is unfolded to form a quadrilateral with the same slant of two waists and different inclination angles, and the two bottoms of the quadrilateral are obviously different in size.

Similarly, in the transition region at the other end of the second spiral section, see region 311 in fig. 2, the two waved rods forming the double spiral line of the second spiral section are combined into one waved rod at the other end, and the wave height mutation of one wave is increased at a certain position in region 312, see fig. 3, the wave heights of the subsequent waves are in a tendency of decreasing along the circumferential direction, so as to form a flush pipe orifice, and finally, the pipe orifice is closed at the wave position where the wave height mutation is increased, so as to form a closed ring 313. A more visual presentation can be seen in fig. 4.

In the transition region of the other end of the first helical section, a wave-shaped rod forming a single helical line can also form a closed loop forming a flush orifice in the same manner as the closing. However, in this embodiment, the closed loop of the first spiral section is selected to form an oblique closed loop by adjusting the wave height of the waveform, that is, the closed loop is biased to one side of the radial section of the tubular shape to form an oblique nozzle, see region 110 shown in fig. 2.

Adjacent turns of a single helix are connected by a first connection member 610 and any helix within a double helix is connected to its adjacent helix by a second connection member 620. The first connecting part and the second connecting part are distributed along the circumference of the tubular shape.

The spiral may have a width along its axial direction to provide greater radial support of the stent. Obviously, the larger the axial width is, the larger the radial supporting force is, but the compliance of the whole spiral line attached to the inner wall of the lumen is reduced, and the attaching area is reduced. The spiral line of the embodiment is formed by a spiral wave-shaped rod, and the wave-shaped rod is provided with a wave-shaped structure which is distributed along the length direction of the wave-shaped rod.

In order to make the performance of the two spiral sections different and meet specific requirements, waveforms of a front spiral turn and a rear spiral turn of the single spiral line are staggered in the circumferential direction of the tube, and waveforms of a front spiral turn and a rear spiral turn of the double spiral line are arranged in parallel in the circumferential direction of the tube. The front and back waveforms are staggered in the circumferential direction of the tube shape, so that the support has more uniform radial supporting force in the section, and the extrusion resistance is enhanced; on the contrary, the front and rear waveforms are arranged in parallel in the circumferential direction of the tube shape, so that the support has consistent flexibility in the axial direction of the section and better compliance.

The waveform of the waveform rod can be selected from the prior art, such as Z-shaped wave, omega-shaped wave, sine wave and the like, and the structural parameters of the waveform rod are selected and adjusted corresponding to the waveform and the size of the bracket so as to obtain the required structural performance of the bracket. The shape of the first and second connection members may also be selected as desired, such as straight, arcuate, S-shaped, etc.

In this embodiment, the wave form of the wave form rod of the bracket is a Z-shaped wave, see FIGS. 1-3; the first connecting part and the second connecting part are dumbbell-shaped with two wide ends and a narrow middle, see fig. 6 and 7, the two ends are fused with the wave crest or the wave trough of the wave rod, the whole is round or elliptic, and the middle width is unchanged. Obviously, in some cases, the intermediate width of the first and second connection members may also be gradual.

Example 2

A further improvement of this embodiment, based on embodiment 1, is that the lead angle of the single helix is no greater than the lead angle of the double helix in the unconstrained stable free expanded state of the stent. The lift angle refers to the inclination angle of a tangent line of a point on the spiral line to the radial section of the bracket. Referring to fig. 1, the complementary angle of the lead angle of the double helix of the second helical segment 300 is α, i.e., the helix angle of the double helix is α, and the complementary angle of the lead angle of the single helix of the first helical segment 100 is β, i.e., the helix angle of the single helix is β, α+.β.

Example 3

Based on embodiment 1 or embodiment 2, a further improvement of this embodiment is that adjacent turns of a single spiral are connected by a first connecting member to the closest crest and trough, and any one spiral within a double spiral is connected by a second connecting member to the closest two crests or two troughs. The length of the first connecting part is significantly smaller than that of the second connecting part, so that the anti-extrusion performance and the flexibility of the two spiral sections are respectively further enhanced.

Referring to fig. 1-4, the first connecting member is angled with respect to the axial direction of the bracket and the second connecting member is substantially parallel with respect to the axial direction of the bracket.

Example 4

A further development of this embodiment, based on embodiment 3, consists in that adjacent first connection elements in a single spiral are arranged offset in the axial direction of the stent, and adjacent second connection elements in a double spiral are arranged in parallel, see the expanded view of the stent of fig. 4.

Example 5

A further improvement of this embodiment, based on embodiment 1, is that this embodiment proposes a self-expanding stent suitable for use in a blood vessel.

Based on the physiological anatomy of human or animal body vessels, particularly inferior vena cava vessels, the present embodiment selects a wave beam having a Z-shaped wave with a wave height of 1-5 mm, the wave height being the vertical distance between adjacent peaks and valleys. In addition, the wave-shaped rod can have 10-25 wave crests or 10-25 wave troughs on each 360-degree spiral turn; the width of the rod body of the wave rod is 0.1-0.4 mm, the width d1 of the first connecting part is 0.2-0.5 mm, and the width d2 of the second connecting part is 0.1-0.3 mm, see fig. 6 and 7; the length of the first connecting part along the axial direction of the bracket is not more than 2mm; the length of the second connecting part along the axial direction of the bracket is larger than the wave height of the wave rod, and the difference value between the length and the wave height is not larger than 2mm; the number of the first connecting parts and the second connecting parts distributed every 360 degrees along the circumferential direction of the tubular shape is 3-8 respectively.

The different numerical combinations within the above parameter ranges can be selected to obtain stents of various specifications, and stents of different specifications can also have different lengths, such as the total length of the stent, the length of the first helical segment, the length of the second helical segment, etc. The total length of the bracket in this embodiment is selected to be 50-120 mm. The length of the double helical section 300 is 30mm to 100mm. If the second helical segment is too long, the stent is at risk of piling up during the release process, resulting in a disturbance of the waveform arrangement of the stent after the stent is released into the vessel.

Example 6

A further improvement of this embodiment, based on embodiment 5, is that the body width of the wavy lever of this embodiment is greater than the widths of the first connecting part and the second connecting part. And the length of the first connecting part along the axial direction of the bracket is not more than 1mm; the second connecting part has a length along the axial direction of the bracket greater than the wave height of the wave rod, and the difference between the length and the wave height is not greater than 1mm.

Example 7

A further improved embodiment is presented on the basis of embodiment 1, the self-expanding stent of this embodiment further comprises a non-helical section 400 comprising an inclined ring surrounding the central axis of the tubular shape, the inclined ring being formed by an annular wave shaped rod, the inclined ring and the closed ring of the single helix in the first helical section being jointly biased to one side of the radial cross section of the tubular shape, see fig. 1-3.

The waveforms of the closed loops of the oblique loops and the first helical segments are staggered in the circumferential direction of the tube shape and connect the peaks and the valleys closest to each other by means of a first connecting member, see fig. 1-4. Four markers are fixedly arranged on the inclined ring to indicate the direction of the inclined opening of the bracket.

Obviously, the non-spiral section can be provided with a plurality of parallel inclined rings, and the inclined rings are connected by corresponding connecting parts, so that the inclined rings are one in the best embodiment.

The circumferential wave form of the diagonal ring can be adjusted to achieve the desired diagonal angle for the stent, see fig. 1, with a diagonal angle of κ. To obtain proper radial support and axial compliance, the helix angles β, α typically need to be chosen within a certain range and may in some cases result in the helix angle β not matching the bevel angle of the lumen, e.g., the bevel of the left common iliac vein opening is a bevel. The oblique ring can be added to obtain a required oblique angle at the front end of the bracket, so that the requirements of special blood vessel physiological anatomy angles are met. Also, the bevel ring has a relatively more stable bevel angle under compression, as well as providing enhanced support at the front end. Normally, κ > β > α is chosen.

Example 8

A further improvement of this embodiment, based on embodiment 7, is that the sum of the lengths of the non-helical section 400 and the first helical section 100 is less than the length of the second helical section 300. Wherein the sum of the lengths of the non-helical section 400 and the first helical section 100 is 10mm to 60mm.

Example 9

A further improvement of this embodiment, based on either embodiment 1 or embodiment 7, is that in the transition zone, one wavy bar, which is composed of two wavy bars, has a tendency to gradually decrease in height and gradually decrease in width of the bar as a whole along the circumference of the stent. The variation of the width of the rod can adjust the difference of different expansion capacities of the wave angles caused by different wave heights when the diameter of the bracket is increased, and the supporting capacity of each radial approach in the transition zone is obtained.

Example 10

Based on any of the foregoing embodiments, this embodiment proposes a further improvement in that the self-expanding stent in its unconstrained free expanded state has a diameter that is monotonically graded along its axis, and the diameter of the first helical segment is generally greater than the diameter of the second helical segment. Namely, the longitudinal section of the bracket is in a cone shape with a large front end and a small rear end;

for self-expanding stents suitable for use in the iliac veins, the diameter of the anterior end is 10 to 18mm and the diameter of the posterior end is 10 to 14mm.

Summary

Obviously, in the above embodiment, the multiple helix is selected as a double helix. However, based on the above description, the person skilled in the art may also select other forms of multi-spirals, for example three, four or more spirals in parallel and co-directional, which may be correspondingly formed by three, four or more wavebars. The wave bars of the multiple spiral lines in the transition zone are combined into a wave bar in pairs until all wave bars are finally combined into a wave bar.

Application of

Referring to fig. 8, the self-expanding stent of example 1 is shown in a post-release position in the left common iliac vein, the physiological anatomy of the left common iliac vein is shown at 702, the anterior orifice of the self-expanding stent is a bezel, and the bezel face is provided with a plurality of markers to indicate the position of the bezel.

For the self-expanding stent of example 7, the front end of the first spiral segment 100 is further provided with a non-spiral segment 400, the oblique ring of the non-spiral segment 400 forms an oblique opening, and the oval oblique opening surface thereof is provided with four markers to indicate the position of the oblique opening, so that the self-expanding stent can be accurately placed in the horn mouth of the left common iliac vein afflux inferior vena cava 701 and stably anchored.

Preparation method

The invention also provides a preparation method of the self-expanding stent, which comprises the steps of cutting a tubular material by using laser and removing redundant parts of the tubular material to obtain a hollow tubular structure with an integrated wavy rod and connecting parts, wherein the tubular material is made of a shape memory material.

Referring to fig. 5, a cutting diagram of a self-expanding stent according to an embodiment of the present invention is shown, the raw material tube is a nickel-titanium alloy tube, fig. 1 to 3 are views of the prepared stent according to the preferred embodiment at different angles after expansion, fig. 4 is a schematic plan-expanding view after expansion, and parameters of the corrugated rod and each connecting rod selected by different specifications of the stent are described in examples 5, 6 and 8.

After laser cutting, the surplus material of the gap between the wave rod and the connecting rod is removed, and the self-expanding stent with the required determined diameter in the free expansion state is obtained through expansion and heat treatment.

Testing

Support positioning and anchoring performance test

The self-expanding stent shown in fig. 1 is placed on the left common iliac vein of sheep (weight 46 Kg) through interventional operation, the diameters of the openings of the left and right iliac veins are 10-11 mm after angiography, and the distal end is about 9mm, so that a 1210060-specification stent is adopted, namely, the diameter of the front end of the stent is 12mm, the diameter of the rear end of the stent is 10mm, the front end of the stent is correspondingly arranged at the opening ends of the left and right iliac veins, and the rear end of the stent is correspondingly arranged at the distal ends of the left and right iliac veins. The left X-ray image a of fig. 9 shows the position of the stent when the front end portion of the stent is released, the right X-ray image B of fig. 9 shows the position of the stent after the stent is completely released, and as can be seen by comparing the two images, the front bevel position of the self-expanding stent is not changed basically, and no obvious forward jump occurs after the stent is released.

After the sheep had been implanted with the stent, the feeding environment was sacrificed after free movement for one month, the iliac veins were dissected, see fig. 11, the stent position was not shifted, the endothelialization of the stent in the blood vessel was good, and the front end of the stent did not enter the inferior vena cava.

Support performance test for bracket

Test method

The radial supporting force of the bracket is measured in a compression mode to characterize the supporting performance of the bracket. With the tooling shown in fig. 10, the bracket is placed on the arc surface between the upper tooling and the lower tooling, the lower clamp is fixed, the upper clamp moves downwards, the moving speed is 20mm/min, the inlet force (the force generated after the self weight of the clamp is removed and the contact is started) is set to be 0.1N, the displacement is calculated after the inlet force is reached, the movement is stopped after the bracket is compressed downwards for 3mm, and the upper clamp moves upwards at the speed of 50mm/min after the bracket is kept at the position for 10 seconds until the clamp is completely evacuated. In the process, the relation between the compression amount and the force of the bracket to the upper clamp is recorded, and the peak value of the force is taken as the radial supporting force of the bracket.

The radial supporting forces of the self-expanding stent shown in fig. 1 and the control stent were measured as described above, and the test results are shown below (the results are the average process after a plurality of measurements).

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The reference substance is a Zilver bracket of COOK company, has a structure similar to an E-luminaexx bracket, is also a hollow bracket formed by cutting a metal tube, and the periphery of the bracket consists of a plurality of groups of annular wavy rods which are axially arranged in parallel and connecting rods for connecting adjacent wavy rods, and is integrally connected with staggered rods which enclose hollow holes.

The standard of the measured bracket is that the diameter of the front end of the bracket shown in the figure 1 is 14mm, the diameter of the rear end of the bracket is 12mm, and the length of the bracket is 60mm; the diameters of the front end and the rear end of the reference substance are 14mm, and the length is 65mm.

The stent in the embodiment of the invention is a cut open-loop stent, and the stent is smaller in shortening under the condition of receiving compression, and the length of the stent cannot be prolonged or shortened even under the condition of flattening the inner cavity of the stent due to non-radial compression. Therefore, the length of the support with the structure cannot be changed after compression, the front end and the rear end of the support cannot be displaced due to expansion, the support has good anchoring force, potential risks caused by the fact that the front end of the support stretches into the inferior vena cava are avoided, and the support is safer.

Claims

1. A self-expanding bracket comprises a supporting structure which forms a hollow pipe shape, wherein the front pipe orifice of the hollow pipe shape formed by the supporting structure is a bevel orifice,

the hollow tubular supporting structure comprises two different types of spiral sections which are formed into a hollow tubular shape and are axially arranged along the hollow tubular supporting structure, wherein the first spiral section comprises a single spiral line, and the second spiral section comprises a double spiral line formed by two parallel spiral lines; the single spiral line and the double spiral line extend in the same direction and in a circumferential shape around the central axis of the tube shape, and one end of each of the adjacent single spiral line and the adjacent double spiral line is combined into a single spiral line in a transition area between the two, and the single spiral line and the double spiral line are respectively closed in other transition areas along the circumferential direction of the tube shape at the other ends to form a closed ring without a free end;

the non-spiral section comprises one or more parallel inclined rings surrounding the central axis of the pipe shape, the inclined rings are formed by annular wavy rods, and the inclined rings and a closed ring of a single spiral line in the first spiral section are jointly biased to one side of the radial section of the pipe shape;

the end face of the bevel connection is formed by an inclined ring.

2. A self-expanding stent as defined in claim 1, wherein: the angle of the bevel opening is matched with the angle of the oblique opening of the left common iliac vein in the human body.

3. A self-expanding stent as defined in claim 1, wherein: the inclined ring forming the inclined port end face is connected with the other inclined ring through a connecting part.

4. A self-expanding stent according to claim 1 or 3, wherein: the bevel is elliptical.

5. A self-expanding stent as defined in claim 4, wherein: the wavy bars forming the oblique rings have a distribution of wavy sizes which varies in the circumferential direction thereof and form substantially flush faces at the oblique end faces.

6. A self-expanding stent as defined in claim 1, wherein: the inclined rings and the closed ring waveforms of the first spiral section are staggered in the circumferential direction of the pipe shape, and the wave crests and wave troughs which are closest to the inclined rings and the closed ring waveforms of the first spiral section are connected through the first connecting part.

7. A self-expanding stent as defined in claim 1, wherein: the first spiral section is configured to have good anti-extrusion performance relative to the second spiral section, can well support a narrow lumen, and the second spiral section has good flexibility performance relative to the first spiral section, and can be fully adapted to a complex curved lumen section.

8. A self-expanding stent as defined in claim 7, wherein: the first helical segment anterior-side placement of the canted loop is configured to further enhance crush resistance and anchoring of the stent at the anterior end.

9. A self-expanding stent as defined in claim 1, wherein: the self-expanding stent has a diameter that is monotonically gradual along its axis in the unconstrained free expanded state and has a maximum diameter at the bezel, with the diameter of the first helical segment being generally greater than the diameter of the second helical segment.

10. A self-expanding stent as defined in claim 1, wherein: the support structure is a unitary structure obtained by cutting a tube of shape memory material.

11. A self-expanding stent as defined in claim 1, wherein: the bevel ring is provided with four markers to indicate the direction of the bevel.

12. A self-expanding stent as defined in claim 11, wherein: the bevel ring forms an elliptical bevel at the bevel, one marker being disposed at each end of the elliptical major and minor axes of the bevel.

13. A self-expanding stent as defined in claim 1, wherein: the waveforms of the front spiral turn and the rear spiral turn of the single spiral line are staggered in the circumferential direction of the pipe, and the waveforms of the front spiral turn and the rear spiral turn of the double spiral line are arranged in parallel in the circumferential direction of the pipe.

14. A self-expanding stent as defined in claim 13, wherein: the adjacent turns of the single spiral line are connected with the wave crest and the wave trough with the closest distance by the first connecting component, and any spiral line in the double spiral lines is connected with the two wave crests or the two wave troughs with the closest distance by the second connecting component;