CN109464213B

CN109464213B - Covered stent and covered stent system

Info

Publication number: CN109464213B
Application number: CN201811563118.XA
Authority: CN
Inventors: 肖本好; 唐江峰
Original assignee: Shenzhen Xianjian Changtong Medical Co ltd
Current assignee: Lifetech Scientific Shenzhen Co Ltd
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-12-15
Anticipated expiration: 2038-12-20
Also published as: CN109464213A

Abstract

The invention discloses a covered stent which comprises a first stent section and a second stent section, wherein the far end of the first stent section is connected with the near end of the second stent section; the area of the cross section of the first bracket section is gradually reduced from the near end to the far end; the first support section comprises a first arc surface and a second arc surface, the first arc surface and the second arc surface are enclosed to form a tubular structure, and the radius of the first arc surface is smaller than that of the second arc surface on the same cross section. The invention also discloses a covered stent system which comprises the covered stent and the main stent, so that after the covered stent and the main stent are matched for use, the covered stent and the main stent are tightly attached to each other, the occurrence of internal leakage is reduced, and sufficient blood can be ensured to flow into branch blood vessels.

Description

Covered stent and covered stent system

Technical Field

The invention relates to the field of medical instruments, in particular to a covered stent and a covered stent system.

Background

The advent of Thoracic aortic endoluminal repair (TEVAR) has fundamentally changed the strategy for treating vascular diseases such as arterial dissections and aneurysms. In recent years, some vascular surgery centers at home and abroad have tried to treat arterial diseases involving the arch part by using the TEVAR technique, on the basis of the great mastery of the technique for treating aortic arch diseases descending from the arch. Often, this type of disease is due to insufficient stent anchoring area or disease affecting the branch vessels, and the aortic stent graft needs to be released from the ascending aorta during surgery to cover a portion of the branch, at which time one or more branch stents need to be implanted to reconstruct the covered branch of the arch in order to ensure that the branch vessels are providing blood after surgery.

There are various reconstruction techniques for branch vessels, and among them, the parallel chimney stent technique is popularized due to low requirements on the intracavity technique and equipment preparation. However, since the aortic stent and the branch arterial stent (also called as a chimney stent) are arranged in parallel, a gap inevitably occurs between the stents, and the I-shaped internal leakage is easily caused. As shown in fig. 1, the chimney holder 02 and the main body holder 01 of the prior art are both cylindrical structures with uniform size, and the risk of inner leakage caused by the cooperation of the holders is high. As shown in fig. 2, after the main body stent 01 and the chimney stent 02 are implanted, the main body stent 01 and the chimney stent 02 are both compressed and deformed by the extrusion of the blood vessel wall, and the main body stent 01 is deformed to be locally concave at the contact position of the main body stent 01 and the chimney stent 02, so that a large gap is formed at the two directly attached edge positions. As shown by the shaded portion in fig. 2, blood easily passes through the gap, thereby causing type I endoleak and affecting the therapeutic effect. Meanwhile, when the main body support 01 and the chimney support 02 are attached in a blood vessel, the maximum strain force is concentrated at the position, inwards concave, of the main body support 01, the local deformation is large, stress concentration is easy to cause, and the position is a high risk point of fatigue fracture of the support in the middle and long term. Therefore, the use of the chimney holder 02 and the body holder 01 according to the prior art causes the fatigue property of the body holder 01 to be lowered. In addition, the inner diameter of the main body part of the chimney support 02 is small, when the chimney support 02 is squeezed by the main body support 01, the chimney support 02 is further compressed, and in a long term, the squeezed part at the near end of the chimney support 02 is possibly narrowed or even blocked, so that the blood supply of a branch blood vessel is insufficient, and the health and even life safety of a patient are affected.

In view of the above, there is a need for a stent graft system that does not leak after use.

Disclosure of Invention

The invention provides a tectorial membrane bracket, which comprises a first bracket section and a second bracket section, wherein the far end of the first bracket section is connected with the near end of the second bracket section; the area of the cross section of the first bracket section is gradually reduced from the near end to the far end; the first support section comprises a first arc surface and a second arc surface, the first arc surface and the second arc surface are enclosed to form a tubular structure, and the radius of the first arc surface is smaller than that of the second arc surface on the same cross section.

In one embodiment, the hardness of the first cambered surface is greater than the hardness of the second cambered surface.

In one embodiment, the distal end of the first stent section is connected to the proximal end of the second stent section by a connecting section which is an annular membrane section with an outer surface that is concave toward the central axis of the second stent section.

In an embodiment, the second stent section is a hollow cylindrical structure and has a central axis, and a projection of the second stent section on a projection plane perpendicular to the central axis is inscribed in a projection of the first cambered surface on the projection plane.

In an embodiment, a projection of the second stent segment on the projection plane is tangent to a midpoint of a projection of the first cambered surface on the projection plane.

In one embodiment, the first cambered surface and the second cambered surface are bent in the same or opposite directions.

In one embodiment, the second arc surface is a plane.

The invention also provides a covered stent system which comprises a main stent and a branch stent, wherein the branch stent is any one of the covered stents.

In one embodiment, the first cambered surface of the branch stent has a radius equal to that of the proximal opening of the main stent.

In one embodiment, the hardness of the second cambered surface is smaller than that of the main body support.

The covered stent provided by the invention comprises a first stent section and a second stent section, the area of the cross section of the first stent section is designed to be gradually reduced from the near end to the far end, the first stent comprises a first cambered surface and a second cambered surface, and the radius of the first cambered surface on the same cross section is smaller than that of the second cambered surface. The covered stent system provided by the invention comprises the covered stent and the main stent, so that after the covered stent and the main stent are matched for use, the covered stent and the main stent are tightly attached to each other, the occurrence of internal leakage is reduced, and sufficient blood can be ensured to flow into the branch blood vessel.

Drawings

FIGS. 1 and 2 are schematic structural views of a main body bracket and a chimney bracket in cooperation with each other in the prior art;

FIG. 3 is a schematic view of the overall structure of a stent graft according to a first embodiment of the present invention;

FIG. 4 is a side view of the stent graft of FIG. 3;

FIG. 5 is an enlarged partial view of the stent graft shown in FIG. 4;

FIG. 6 is a front view of the stent graft of FIG. 3;

FIGS. 7a and 7b are each a front view of a stent graft according to other embodiments of the present invention;

FIG. 8 is a covered stent system according to an embodiment of the present invention, including the covered stent shown in FIG. 3;

FIG. 9 is an elevation view of the stent graft system of FIG. 8;

FIG. 10 is a schematic view of the overall structure of a stent graft according to a second embodiment of the present invention;

FIG. 11 is a top view of the stent graft of FIG. 10;

FIG. 12 is a front view of the stent graft of FIG. 10;

FIG. 13 is a stent graft system according to another embodiment of the invention, comprising the stent graft shown in FIG. 10;

FIG. 14 is a stent graft according to another embodiment of the present invention.

Detailed Description

For better understanding of the technical solutions and advantages of the present invention, the following embodiments are further illustrated in the accompanying drawings, and the following specific embodiments are only some preferred embodiments and are not intended to limit the present invention.

In the field of medical devices, the direction of blood flow in is defined as "proximal" and the direction of blood flow out is defined as "distal". The term "coupled" as used below may refer to a direct connection between two elements or a connection through a third element.

The covered stent comprises a support main body and a covered membrane, wherein the covered membrane is arranged on the support main body, namely the covered membrane can be arranged inside and/or outside the support main body. The two ends of the supporting main body are provided with openings, and the openings at the two ends are communicated. The support main body can be a net structure formed by weaving braided wires, or can be a plurality of support units formed by cutting tubes through laser firstly, and the support main body is formed by connecting the plurality of support units. The support body should have good support and shape memory properties, and the material may be selected from nitinol. The covering film can be made of a high polymer material with good biocompatibility, such as PET or PTFE. For convenience of description, the following figures do not distinguish between the support body and the stent graft, and only show the overall profile structure of the stent graft.

In addition, the covered stent system comprises a main stent and a branch stent, wherein the branch stent is the covered stent of the invention and is used for providing blood for a branch blood vessel; the main body support is a hollow tubular structure used for supporting the inner wall of the aorta, and also comprises a supporting main body and a covering film.

Example one

As shown in FIGS. 3-6, the stent graft 100 of the present embodiment includes a first stent section 10, a second stent section 20, and a connecting section 30. Wherein the distal end of the first stent segment 10 is connected to the proximal end of the second stent segment 20 by a connecting segment 30. The second stent segment 20 is intended for implantation in a branch vessel to provide blood flow to the branch vessel. The second stent section 20 is of a hollow cylindrical structure and has a longitudinal central axis, a cylindrical radius R20, R20 may range from 3mm to 10 mm.

The cross-sectional area of the first stent section 10 tapers from the proximal end to the distal end and is larger than the cross-sectional area of the second stent section 20 except at the distal end face. The first bracket section 10 is formed by enclosing a first cambered surface 11 and a second cambered surface 12, and the first cambered surface 11 and the second cambered surface 12 are in smooth transition. Further, the radius R11 at the proximal end of the first arc 12 should be less than the radius R12 at the proximal end of the second arc. Like this, the crookedness of second cambered surface 12 is less, can guarantee that tectorial membrane support and main part support use together, and the upper portion deflection of the second cambered surface 12 and the main part support of mutual contact is little, and closely laminating between the two can reduce the emergence of interior hourglass. The range of R11 can be 10-23 mm, and the first cambered surface 11 and the relative undeformed part of the main body support form a complete circle to conform to the inner wall of the blood vessel when the covered stent 100 is matched with the main body support for use, so that internal leakage is avoided; the value range of R12 can be R12 is more than or equal to 14mm, and R12 is ensured to be more than R11. When the second arc 12 is a plane as shown in fig. 6, R12 can be considered to be infinite.

It is understood that, in other embodiments, the second arc surface 12a may have the structure shown in fig. 7a, that is, the second arc surface 12a and the first arc surface 11a are bent in the same direction and are bent toward the same side, that is, the first arc surface 11a protrudes outward relative to the central axis, and the second arc surface 12a is recessed inward relative to the central axis; or, the second arc surface 12b may also be the structure shown in fig. 7b, that is, the bending directions of the second arc surface 12b and the first arc surface 11b are opposite, and the two arc surfaces are bent toward opposite sides, that is, the first arc surface 11b and the second arc surface 12b both protrude outward relative to the central axis, at this time, even if the second arc surface 12b protrudes out of the central axis, because the radius of the second arc surface 12b is greater than the radius of the first arc surface 11b, when the body support is used in cooperation, the second arc surface 12b can still be tightly attached to the outer surface of the body support, thereby reducing the occurrence of inner leakage.

In order to make the second cambered surface 12 better adapt to the shape of the main stent when the stent graft 100 is used with the main stent, the hardness of the first cambered surface 11 is set to be greater than that of the second cambered surface 12. By the arrangement, the second cambered surface 12 is easier to deform compared with the first cambered surface 11, and the first cambered surface 11 can better keep the shape of the opening at the proximal end of the first bracket section 10, so that blood can smoothly flow in. The difference in hardness between the two arcs can be achieved by controlling the knitting density or the yarn diameter of the knitting yarn, for example, the knitting density of the first arc 11 can be made greater than the knitting density of the second arc 12, or the yarn diameter of the knitting yarn of the first arc can be made greater than the yarn diameter of the knitting yarn of the second arc. The same or similar measures can be taken for the stent formed by cutting.

As can be seen from fig. 4, the generatrix of the second bracket segment 20 may be tangent to the arc vertex of the first arc surface 11, i.e. the projection of the second bracket segment 20 on the projection plane perpendicular to its central axis shown in fig. 6 is inscribed on the projection plane of the first arc surface 11. This avoids the formation of gaps between the first stent section 10 and the vessel. In this embodiment, the tangent point is a midpoint of the projection of the first arc surface 11. The second arc surface 12 forms a certain angle a with the central axis, and the range of a may be greater than 0 ° and less than or equal to 50 °. When the radius R20 of the second stent section 20 is determined, the range of the angle a is mainly determined by the distance L11 from the proximal end to the distal end of the first curve 11 on the first stent section 10 and the distance H between the midpoint of the first curve 11 and the midpoint of the second curve 12 on the proximal end of the first stent section 10. Preferably, L11 ranges from 15mm ≦ L11 ≦ 20 mm. L11 should not be too long or too short, and after L11 is larger than 20mm, when the covered stent and the main stent are used in a matched mode, the joint part between the covered stent and the main stent is correspondingly lengthened, and the risk of internal leakage is easily increased; if the L11 is less than 15mm, the anchoring length of the covered stent on the main body stent is insufficient, and the use performance is influenced. And H may optionally range from less than radius R11 proximal to first curve 11 but greater than the diameter of second stent segment 20, i.e., 2 x R20. H needs to be larger than the diameter of the second stent section 20 to ensure normal blood supply of the branch vessel; meanwhile, if H is too large, the proximal opening of the first stent 10 is too large, which may cause the main stent blood flow inlet to be relatively reduced, thereby affecting the blood flow supply of the main aortic vessel. H should be less than radius R11 at the proximal end of first arc 11.

As shown in FIGS. 4 and 5, the connecting segment 30 is an annular stent graft segment without a supporting body, so as to facilitate relative movement between the first stent segment 10 and the second stent segment 20 and improve the overall compliance of the stent graft 100. The outer surface of the connecting section 30 is a concave surface recessed toward the central axis of the second carrier section 20, and the connecting section 30 is a concave surface, so that the deposition of the coating film can be avoided. And the axial length L30 of the connecting section 30 cannot be too long because there is no supporting body, and if L30 is too long, the connecting section 30 is easily squeezed or piled up by the blood vessel, resulting in a narrow blood passage and being unfavorable for blood circulation. Thus, the length of L30 may be selected to be less than one third of the length of L11. It will be appreciated that in other embodiments, the connector segments may not be provided and the distal end of the first stent segment and the proximal end of the second stent segment may be directly connected.

FIGS. 8 and 9 illustrate a stent graft system 300 including the stent graft 100 of the present embodiment, and the stent graft 100 of the present embodiment plays a role in the stent graft system 300 mainly to ensure normal blood supply to a branch vessel, so the stent graft 100 can also be referred to as a branch stent 100. The stent graft system 300 also includes a main body stent 200 for supporting the aorta. The proximal opening of the main body bracket 200 is circular.

In using the stent graft system 300, the main stent 200 is first implanted at the target site, and the branch stent 100 is then implanted, so that the branch stent 100 is flush with the proximal end surface of the main stent 200, and the branch stent 100 is not completely crushed by the main stent 200 to ensure that part of the blood can flow into the branch stent 100. After the main body stent 200 and the branch stent 100 are implanted, the second stent section 20 is located in the branch vessel, the second cambered surface 12 of the first stent section 10 is in contact with the outer surface of the large-bending side of the main body stent 200, and both have certain deformation.

Compared with the prior art, the first bracket 10 of the branch bracket 100 of the invention is shaped like a funnel with a large opening facing the near end, the contact surface between the second cambered surface 12 and the main bracket 200 is larger, the main bracket 200 does not form local concave, the local maximum strain of the main bracket 200 is greatly reduced, stress concentration is avoided, and the fatigue life of the main bracket 200 is greatly prolonged. In addition, the outer contour of the combination of the portion of the main body stent 200 not in contact with the branch stent 100 and the first cambered surface 11 of the branch stent 100 is approximately circular or elliptical, and blood can flow in from the proximal end opening of the main body stent 200 and the proximal end opening of the branch stent 100, respectively. To better avoid endoleak, it is preferable that the radius R11 of the first cambered surface 11 is equal to the radius R200 of the proximal opening of the main body stent 200 so as to conform to the cross-sectional shape of the blood vessel. Furthermore, the hardness of the second cambered surface 12 can be set to be smaller than that of the main body support 200, so that the second cambered surface 12 is easier to deform, has better adaptability with the outer surface of the main body support 200, and has better inner leakage prevention effect. Meanwhile, it is necessary to ensure sufficient blood entering the main body stent 200, so that the area of the proximal opening of the branch stent 100 is limited to not more than half of the area of the proximal opening of the main body stent 200 after the branch stent 100 and the main body stent 200 are implanted. Meanwhile, in order to ensure that the branch blood vessels supply sufficient blood and do not influence the blood supply of the main body stent part, the proximal opening area S of the first stent section is defined as S1< S ≦ 3S 1, wherein S1 is the proximal opening area of the second stent section.

To sum up, the tectorial membrane stent of this embodiment and the tectorial membrane system that contains the tectorial membrane stent of this embodiment compare with prior art, through the structure that includes first support section and second support section with the tectorial membrane stent setting, and the area of first support section cross section is by near-end to distal end gradually littleer, and first support includes first cambered surface and second cambered surface, the radius of first cambered surface is less than the radius of second cambered surface on the same cross section, make this tectorial membrane stent and main part support cooperation use after, the laminating is inseparabler between the two, the emergence of interior hourglass between tectorial membrane stent and the main part support that can significantly reduce, can guarantee simultaneously that there is sufficient blood inflow branch blood vessel.

Example two

As shown in FIGS. 10-12, the stent graft 400 of the present embodiment has substantially the same structure as the stent graft 100 of the first embodiment, except for the first stent section. The proximal end face of the first stent section 40 of this embodiment forms an angle with the central axis of the second stent section 50, which is acute. The first stent section 40 of this embodiment may be considered to be formed by beveling a portion of the proximal end of the stent graft 100 of the first embodiment. As seen from the top view of FIG. 11, the lengths L1 and L2 of the two sides of the first support section 40 are not equal, that is, there is a length difference Δ L between the two, and the value of Δ L may be 0-15 mm, preferably 5-10 mm. When Δ L is 0, the stent graft 100 of the first embodiment. Meanwhile, the value range of the short sides in L1 and L2 is ensured to be the same as that in the first embodiment, namely, the value range is 15 mm-20 mm. It should be understood that the present invention does not limit which of the two sides of the first bracket section 40 is the long side and which is the short side as long as the lengths of the two sides satisfy the above conditions. As can be seen from fig. 12, on a plane of projection perpendicular to the central axis, the projection of the second stent segment 50 is inscribed in the projection of the first arc of the first stent segment 40 on this plane of projection, but the point of tangency is offset from the midpoint of the first arc.

In the actual implantation process of the branch stent, the proximal port of the branch stent is difficult to be flush with the proximal port of the main stent when the branch stent is released in a blood vessel, and the branch stent is generally deflected by a certain angle. Thus, in this embodiment, the proximal end of the first stent section 40 is configured as a chamfered surface, and after the branch stent is implanted, as shown in FIG. 13, the port at the proximal end of the first stent section 40 is just flush with the proximal port of the main stent 500. To increase the positioning of the branch stent, visualization points may be provided at the proximal port locations of the first stent section 40 to align the branch stent ports with the edges of the main stent proximal end when the branch stent is released.

Compared with the first embodiment, the covered stent of the embodiment is more suitable for the actual operation condition of releasing the stent in the process of implanting the stent, so that the branch stent is flush with the proximal end port of the main stent, and the effective area of the branch stent for blood to flow into can be increased. On the other hand, the stent is also very beneficial to the loading of the stent into the sheath tube, the opening of the proximal end where the first stent section is located in the covered stent is larger than the opening of the distal end where the second stent section is located, so that the sheathing at the proximal end position is possibly difficult, the proximal end of the first stent section is arranged to be a chamfer, the circumferential volume of the proximal end of the compressed stent is reduced, and the loading of the stent into the sheath tube is facilitated.

It will be appreciated that in order to facilitate manufacture and to make the graft more uniform, in other embodiments, the stent graft may be configured as shown in FIG. 14, i.e., the proximal end of the second stent segment 70 extends from the distal end of the first stent segment 60 to the interior of the first stent segment 60 or to the proximal end of the first stent segment 60. Thus, the first frame section 60 and the second frame section 70 can be separately manufactured and then the first frame section 60 can be sewn or adhered to the outside of the second frame section 70.

It should be understood that the above-mentioned embodiments are only some preferred embodiments, and not intended to limit the present invention, and those skilled in the art can make simple substitutions on the part of the structure according to actual needs, and that insubstantial changes without departing from the spirit of the present invention are within the scope of the present invention, which is subject to the claims.

Claims

1. A covered stent comprises a supporting main body and a covering film, wherein the covering film is arranged on the supporting main body, and the covered stent is characterized by comprising a first stent section and a second stent section, wherein the far end of the first stent section is connected with the near end of the second stent section through a connecting section, and the connecting section is an annular covering film section with the outer surface sunken towards the central axis of the second stent section; the area of the cross section of the first bracket section is gradually reduced from the near end to the far end; the first support section comprises a first arc surface and a second arc surface, the first arc surface and the second arc surface are enclosed to form a tubular structure, and the radius of the first arc surface on the same cross section is smaller than that of the second arc surface; the first cambered surface and the second cambered surface both comprise a supporting main body and a covering film.

2. The stent graft of claim 1, wherein the first curve has a hardness greater than a hardness of the second curve.

3. The stent graft of claim 1, wherein the second stent segment is a hollow cylindrical structure and has a central axis, and a projection of the second stent segment on a projection plane perpendicular to the central axis is inscribed in a projection of the first cambered surface on the projection plane.

4. The stent graft of claim 3, wherein a projection of the second stent segment on the plane of projection is tangent to a midpoint of a projection of the first arc surface on the plane of projection.

5. The stent graft of any one of claims 1-4, wherein the first curved surface curves in the same or opposite direction as the second curved surface.

6. The stent graft of any one of claims 1-4, wherein the second curved surface is planar.

7. A stent graft system comprising a main stent graft and a branch stent graft according to any one of claims 1 to 4.

8. The stent graft system of claim 7, wherein the radius of the first curved surface of the branch stent is equal to the radius of the proximal opening of the main stent.

9. The stent graft system of claim 7, wherein the second curved surface has a hardness less than a hardness of the main body stent.