CN111374809B

CN111374809B - Vertebral artery stent

Info

Publication number: CN111374809B
Application number: CN202010218321.4A
Authority: CN
Inventors: 张弛; 柳朝晖; 林贝勒
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2021-07-27
Anticipated expiration: 2040-03-25
Also published as: CN111374809A

Abstract

The invention discloses a vertebral artery stent, which is designed aiming at the problem of restenosis after the implantation of a vertebral artery initial stent, and consists of annular support bodies which are longitudinally stacked and connecting ribs which are connected with the adjacent annular support bodies. The support both sides divide into for the great and less two arc side of camber, can carry out the support of not equidimension to the characteristics of the initial segment blood vessel of vertebral artery, make the vascular wall receive different holding power, form asymmetric blood vessel cross-section to change the hemodynamic environment wherein. Meanwhile, in the stent, the connecting ribs with different structures are adopted between one side with large curvature and one side with small curvature of the adjacent annular support bodies, so that the direction of the stent can be distinguished conveniently, and the direction can be better distinguished when the stent is placed into a vertebral artery blood vessel.

Description

Vertebral artery stent

Technical Field

The invention belongs to the field of blood vessel stents, and particularly relates to a blood vessel stent implanted into vertebral artery.

Background

Cerebrovascular disease is one of three main diseases causing human death, cerebral ischemic stroke accounts for about 80% of cerebrovascular disease, and cerebrovascular stenosis is the most important cause of cerebrovascular disease. The vertebral artery initial part stenosis accounts for 25 to 40 percent of all cerebrovascular stenosis. The morphological change caused by the drug treatment can not be reversed, and the part is not suitable for surgical operation due to the factors of large treatment technical difficulty, high risk and the like. Since the 20 th century and the 80 th century, endovascular angioplasty was used for the treatment of vertebral artery stenosis, including balloon dilatation and stenting, with high success rate, but the problem of postoperative restenosis was not negligible. Restenosis refers to a stenosis with a degree of recurrence at the site of original treatment of > 50%. If the treatment is carried out by balloon dilatation, the restenosis rate is about 75-100% within one year; the rate of restenosis after stenting is approximately 10% to 43%.

Because the tube diameter of the vertebral artery initial section is thin and the position is special, the incidence rate of restenosis after the stent implantation is obviously higher than that of carotid artery stent implantation. The influence factors include the following aspects: stent type, post-operative drug treatment, control of atherosclerosis-related risk factors and other factors including pathological and technical operational aspects, and the like. The specific analysis is as follows: (1) the vertebral artery originates from the subclavian artery, and the bifurcation angle is larger, so that the blood flow velocity and the wall shear stress distribution of the vertebral artery present remarkable asymmetric characteristics to induce asymmetric stenosis, and the asymmetric hemodynamics environment is not changed after the stent is implanted, so that the restenosis is difficult to avoid; (2) the restenosis after the treatment of coronary artery stenosis by balloon dilatation is closely related to the elastic retraction of blood vessels, and the restenosis after the vertebral artery stent is implanted into the operation is also the same, because the tube cavity of the initial segment of the vertebral artery is thin, the structure of the vessel wall is rich in elastin and smooth muscle, the tube cavity is easy to retract, and the plaque at the stenosis part is usually relatively hard, and the tube wall is not easy to expand, thereby increasing the retraction force of the blood vessels; (3) the difference in the suitability of the selected stent type to the diseased vessel alters the tissue structure of the vessel, thereby promoting restenosis, and the unsuitable vertebral artery stent increases the internal stress of the vessel, breaks the internal elastic membrane, overstretches the tunica media of the vessel, and causes the excessive proliferation of muscle fibers and neointima. The research of the stent implantation shows that although the existing related stent can improve the diameter of vertebral artery and the blood supply of posterior circulation and reduce the incidence rate of stroke events, the incidence rate of restenosis is high, the long-term curative effect is influenced, and other stent types suitable for the stenosis of the vertebral artery proximal segment still need to be searched. The invention patent CN201721319460.6 proposes a bell-mouth-shaped balloon dilatation stent device for a vertebral artery opening part, which can solve the adaptation problem of the proximal end and the distal end to a certain extent, but does not greatly improve the hemodynamic environment of asymmetric stenosis and can not solve the restenosis problem after stent implantation.

Disclosure of Invention

Aiming at the defects of the prior art, the invention discloses a novel bracket aiming at the asymmetrical stenosis of the vertebral artery starting part, which has the advantages of improving the local hemodynamic environment, improving the use efficiency, solving the problem of the restenosis of the vertebral artery starting part caused by the asymmetrical hemodynamic environment after the bracket is implanted and the problem that the bracket can not be used for a long time.

Because of the special blood vessel shape of the initial segment of the vertebral artery blood vessel, the blood flow speeds on the same radial section are greatly different, so that the shearing force applied to the blood vessel wall is different. The shear force on the side with higher blood flow velocity is larger, and the shear force on the side with lower blood flow velocity is relatively smaller. Because the side with smaller shearing force is more likely to be narrowed, the radial section of the tapered artery stent is asymmetric ellipse-like and consists of two arc surfaces at the side with larger curvature and the side with smaller curvature. The method specifically comprises the following steps:

the support is composed of annular supports which are vertically stacked and connecting ribs which connect adjacent annular supports. The annular support body is a wave-shaped annular structure formed by U-shaped support units which are sequentially arranged in the circumferential direction; the U-shaped structures on the left side and the right side have different opening angles, and the equivalent stiffness of the side with small curvature is larger than that of the side with large curvature.

Two cambered surfaces through the design support have different curvatures, can carry out the support of different degrees to the characteristics of the blood vessel of the initial segment of vertebral artery, make the vascular wall receive different holding power, form asymmetric blood vessel cross-section to change the hemodynamic environment wherein. Wherein, the side with larger curvature corresponds to the side of the blood vessel with larger blood flow velocity in the blood vessel, namely, larger shearing force, and the side with smaller curvature corresponds to the side of the blood vessel with smaller blood flow velocity in the blood vessel, namely, smaller shearing force. Can well inhibit the side which is easy to generate restenosis from generating stenosis, thereby reducing the probability of generating restenosis at the initial segment of vertebral artery blood vessel.

Meanwhile, in the stent, the connecting ribs with different structures are adopted between one side with large curvature and one side with small curvature of the adjacent annular support bodies, so that the direction of the stent can be distinguished conveniently, and the direction can be better distinguished when the stent is placed into a vertebral artery blood vessel.

The invention has the advantages that:

1. when the vertebral artery stent is placed, one side with smaller curvature of the vertebral artery stent corresponds to the narrow side according to the characteristics of the hemodynamics of the vertebral artery blood vessel, so that the supporting force of blood flow on the blood vessel wall can be well balanced, and the restenosis rate of the vertebral artery blood vessel is greatly reduced.

2. After the vertebral artery stent is implanted, the hemodynamics environment of the vertebral artery stenosis part is changed, so that the problems of low flow rate and low wall shear stress of the vertebral artery starting end are greatly reduced, and the occurrence of restenosis is avoided.

3. The vertebral artery stent can not increase the operation difficulty of the existing implanting technology of the vertebral artery stent.

Drawings

FIG. 1 is a cross-sectional view of the vertebral artery stent of the invention.

Fig. 2 is a structural schematic diagram of two sides of the vertebral artery stent after being unfolded.

FIG. 3 is a schematic view of the vertebral artery stent of the present invention after being placed in the stenotic vertebral artery.

Fig. 4 is a schematic diagram of the vertebral artery stent implanted in a dilated stenotic blood vessel.

In the figure:

1-annular support body 2-connecting rib 101-U-shaped support unit

Detailed Description

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

The vertebral artery stent is an asymmetric vascular stent and comprises annular support bodies 1 and connecting ribs 2 used for connecting two adjacent groups of annular support bodies 1, and is shown in figures 1 and 2.

The annular support body 1 is a wave-shaped annular structure formed by a plurality of U-shaped support units 101 which are sequentially arranged in the circumferential direction. The number of the U-shaped supporting units 101 on the left side and the right side of the annular supporting body 1 can be the same or different, the left side uses the material rigidity to be larger than the right side material rigidity, the opening angle of the U-shaped supporting unit 101 on the left side is larger than the opening angle of the U-shaped supporting unit 101 on the right side, the left side curvature is smaller than the right side curvature, and the arc length ratio of the left side to the right side is 1: 2; finally, the asymmetric-structure annular support body 1 is formed. The left side with small curvature is usually arranged on the easy-to-narrow side of the blood vessel wall, and compared with the traditional circular section with consistent transverse width ratio, the asymmetric transverse width ratio design structure can effectively improve the local hemodynamic structure of the blood vessel narrow part; the blood vessel stent has directionality due to the asymmetric structure, so that the blood vessel interface after the stent is expanded is asymmetric and round, the hemodynamic environment of the narrow side in an eccentric narrow blood vessel can be improved, and the occurrence of restenosis is reduced.

A plurality of annular support body 1 of above-mentioned structure vertically sets up, and the splice bar 2 that adopts different structures between the left side of adjacent annular support body 1 and the right side links to each other, and the position of meeting between splice bar 2 and the adjacent annular support body 1 lies in crest and trough department of U type supporting element in adjacent annular support body 1. Wherein, the right sides with large curvature are connected by I-shaped connecting ribs 2; the left sides with small curvature are connected by any one of V-shaped, W-shaped, S-shaped or other combined connecting ribs. The left side and the right side of the annular support body 1 are connected by adopting different types of connecting ribs, and finally the marking of the direction of the blood vessel support is realized.

The design structure of the blood vessel support can enable the diameter of a narrow blood vessel to be restored to the diameter of a normal blood vessel to a greater degree, the inner and outer side tube walls of the vertebral artery at the initial section are supported by different degrees through the asymmetric structure, the physiological characteristics of the narrow blood vessel are better met, the shearing force applied to the two sides of the blood vessel is balanced, the problem of infirm support is effectively solved, and the incidence rate of restenosis after a stent implantation is reduced. The diameter of the stent body is usually designed to be equal to or slightly larger than the inner diameter of the blood vessel at the desired stent position.

The cross sections of the annular support body 1 and the connecting ribs 2 are both rectangular structures, so that the processing is convenient, and the stress generated to blood vessels is relatively uniform. Meanwhile, the annular support body 1 and the connecting ribs 2 are designed to be made of one or more of stainless steel, cobalt-chromium alloy, nickel-titanium alloy, biodegradable polymer material, biodegradable metal, pure magnesium, magnesium alloy, pure iron or iron alloy.

The vertebral artery stent can be designed into a bare stent, or a drug-coated vascular stent or a degradable vascular stent, and is prepared by a laser engraving method, or a weaving method, or a 3D printing method.

Example (b):

in this embodiment, the stent has 5 annular supports and eight sets of connecting ribs 2, each set having four connecting ribs. In each ring support 1, the side with the smaller curvature has 4U-shaped support units, and the side with the larger curvature has 4U-shaped support units. Two adjacent annular supporting bodies 1 adopt a closed-loop wave crest-to-wave trough connection mode, and the wave crests are connected with the wave troughs through connecting ribs 2, in the embodiment, the connecting ribs 2 on one side with large curvature all adopt I shapes, and the connecting ribs 2 on one side with small curvature all adopt V shapes; the I-shaped connecting ribs and the V-shaped connecting ribs can be distinguished under X-ray perspective.

Due to the difference of the opening angles of the U-shaped structures at the two sides, the equivalent stiffness of the side of the annular support body 1 with small curvature is larger than that of the side with large curvature, namely the curvature of the left side surface of the I-shaped connecting rib is larger than that of the right side surface of the V-shaped connecting rib after the annular support body is unfolded. When the stent is delivered to a target lesion part by the delivery catheter, the direction is adjusted to ensure that one side of the V-shaped connecting rib corresponds to the side of the blood vessel wall with smaller shearing force, as shown in figure 3, one side of the I-shaped connecting rib corresponds to the side of the blood vessel wall with larger shearing force, and after the adjustment is finished, the saccule is pressurized and expanded in vivo to open the narrow blood vessel wall, so that the lesion blood vessel is recovered to be smooth, as shown in figure 4; after the stent is unfolded, whether the stent placement direction is correct or not is checked again, and the catheter is withdrawn without error.

When the conveying catheter conveys the blood vessel support to a target lesion part, the direction is adjusted to enable one side, with the V-shaped connecting rib, of the conveying catheter to be close to the side of the blood vessel wall with smaller shearing force, and after the adjustment is finished, the balloon is pressurized and expanded in vitro to expand the narrow blood vessel wall and enable the lesion blood vessel to be recovered to be smooth; and the placing direction of the stent is checked again after the stent is unfolded, so that one side of the connecting rib in the V shape corresponds to the side of the vessel wall with smaller shearing force, one side of the connecting rib in the I shape corresponds to the side of the vessel wall with larger shearing force, and the catheter is withdrawn without error after checking.

The vertebral artery stent has the advantages that the diameter of a narrow blood vessel can be restored to the normal diameter to a greater extent by the aid of the design structure of the vertebral artery stent, the inner and outer side walls of the vertebral artery at the initial section are supported by different degrees due to the design structures of the two different curvature sides of the vertebral artery stent, the physiological characteristics of the narrow blood vessel are better met, the shearing force applied to the two sides of the blood vessel is balanced, accordingly, the problem of unstable support is effectively solved, and the incidence rate of restenosis after stent implantation is reduced.

Claims

1. A vertebral artery stent characterized by: the vertebral artery stent is characterized in that the radial section is in an asymmetric ellipse-like shape and consists of two arc-shaped surfaces with larger curvature and smaller curvature, and the vertebral artery stent consists of annular support bodies which are longitudinally stacked and connecting ribs for connecting the adjacent annular support bodies;

the annular support body is a wave-shaped annular structure formed by U-shaped support units which are sequentially arranged in the circumferential direction; the left and right sides U-shaped structure opens the angle differently, and the equivalent stiffness of the one side that the camber is little is greater than the equivalent stiffness of the one side that the camber is big: the left sides and the right sides of the adjacent annular supporting bodies are connected by adopting connecting ribs with different structures, and the connecting positions of the connecting ribs and the adjacent annular supporting bodies are positioned at the wave crests and the wave troughs of the U-shaped supporting units in the adjacent annular supporting bodies;

the side with larger curvature of the annular support body corresponds to the side surface of the blood vessel with larger shearing force in the blood vessel, and the side with smaller curvature corresponds to the side surface of the blood vessel with smaller shearing force in the blood vessel.

2. A vertebral artery stent as defined in claim 1, wherein: the arc length ratio of the side with small curvature to the side with large curvature is 1: 2.

3. a vertebral artery stent as defined in claim 1, wherein: the sides of the annular supporting bodies with large curvature are connected by I-shaped connecting ribs; the sides with small curvature are connected by adopting any connecting rib.

4. A vertebral artery stent as defined in claim 1, wherein: the material is metal or nonmetal.

5. A vertebral artery stent as defined in claim 1, wherein: bare stents are used, either drug-coated vascular stents or degradable vascular stents.

6. A vertebral artery stent as defined in claim 1, wherein: the fabric is prepared by a laser engraving method, or a weaving method, or a 3D printing method.