CN109419570B - Tectorial membrane bracket and preparation method thereof - Google Patents

Abstract

The invention relates to a covered stent and a preparation method thereof. The utility model provides a tectorial membrane support, includes support body and tectorial membrane, the support body have first surface and with the second surface that first surface is relative, the tectorial membrane includes first diaphragm and second diaphragm, first diaphragm is located first surface, the second diaphragm is located the second surface and with first diaphragm bonding, the tectorial membrane still include with support body rigid coupling's connecting piece, the connecting piece be located first diaphragm with between the second diaphragm, the connecting piece with at least one bonding in first diaphragm and the second diaphragm. The tectorial membrane support can improve the joint strength between tectorial membrane and the support body.

Description

Tectorial membrane bracket and preparation method thereof

Technical Field

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

Background

The existing endograft stent is divided into a bare stent formed by a metal stent and a covered stent formed by a covered material and the metal stent according to the structural form type, wherein the covered stent adopts an anti-seepage covered material to wrap the stent, and when the stent is released at a lesion position, the covered material plays a role in isolating blood flow.

The covered stent generally adopts a mode of covering and wrapping a metal stent by heat treatment and stitching with single-layer or multi-layer covered materials. One type of prior art stent is a stent made of polyethylene terephthalate (PET) and is generally fixed to one or both sides of a metal stent by stitching. Referring to fig. 1 to 3, when using an expanded polytetrafluoroethylene (ePTFE) coating 240, the coating 240 has a high elongation and is easily deformed, and is not suitable for connecting the metal stent 210 by a sewing process, in which the ePTFE is required to be melted at a high temperature (such as 327 ℃) and the films are bonded to each other after cooling, the ePTFE inner film 241 and the ePTFE outer film 243 completely or partially encapsulate the metal stent 210, and the contact portion of the inner film and the outer film is bonded to form a whole after heat treatment, so that the metal stent 210 is fixed between the inner film 241 and the outer film 243.

Referring to fig. 4 to 6, the ePTFE material itself is not adhered to the metal bracket 210, and a certain gap 260 exists when the inner film 241 and the outer film 243 are combined with the metal wires of the metal bracket 210, so that the metal bracket 210 is easy to loosen between the inner film 241 and the outer film 243 under the action of external force, and a tearing force is generated on the adhesive contact surface between the inner film 241 and the outer film 243, under the action of the force, the inner film 241 and the outer film 243 are gradually separated, and the separation is irreversible because the ePTFE loses adhesion at normal temperature, which may cause the inner film 241 and the outer film 243 to be partially separated, even the metal bracket is separated from the cover 240 to fail.

Disclosure of Invention

Based on this, it is necessary to provide a stent graft capable of improving the strength of the connection between the stent graft and the stent graft, and a method for producing the same.

The utility model provides a tectorial membrane support, includes support body and tectorial membrane, the support have first surface and with the second surface that first surface is relative, the tectorial membrane includes first diaphragm and second diaphragm, first diaphragm is located first surface, the second diaphragm is located the second surface and with first diaphragm bonding, the tectorial membrane still include with support body rigid coupling's connecting piece, the connecting piece be located first diaphragm with between the second diaphragm, the connecting piece with at least one bonding in first diaphragm and the second diaphragm.

Above-mentioned tectorial membrane support, tectorial membrane support is under the effect that receives the external force, and the support body is together fixed through one of connecting piece and first diaphragm and second diaphragm to be difficult for taking place not hard up between first diaphragm and second diaphragm, thereby increased the joint strength of tectorial membrane and support body, reduced the tectorial membrane support and when atress or deformation the aversion of support body leads to the fact the risk of tectorial membrane support inefficacy.

In one embodiment, the connector is an envelope that surrounds the stent body.

In one embodiment, the ratio of the sum of the thicknesses of the first and second diaphragms to the thickness of the envelope is 4: 1-20: 1.

In one embodiment, the bracket body comprises a wave ring, the wave ring comprises wave crests, wave troughs and side rods, the side rods are connected with the wave crests and the wave troughs, and the thickness of the coating on the surfaces of the wave crests and the wave troughs is smaller than that of the coating on the surfaces of the side rods.

In one embodiment, at least one of the first surface and the second surface is recessed inward to form a groove, and the connector is received in and fixed to the groove.

In one embodiment, the material of the connecting piece is the same as the material of the first membrane and/or the second membrane.

The preparation method of the covered stent comprises the following steps:

Forming a connecting piece wrapping the bracket body on the bracket body; and

The first membrane is arranged on the first surface of the bracket body, the second membrane is arranged on the second surface of the bracket body, and the first membrane and the second membrane are subjected to heat treatment so that the first membrane, the second membrane and the connecting piece are bonded and fixed.

In one embodiment, the step of forming the connecting piece on the bracket body to wrap the bracket body specifically includes: and winding the connecting piece on the bracket body to form a coating wrapping the bracket body.

In one embodiment, the step of forming the connecting piece on the bracket body to wrap the bracket body specifically includes: and forming a coating on the surface of the bracket body to obtain the connecting piece.

The other preparation method of the covered stent comprises the following steps:

providing the bracket body, wherein at least one of the first surface and the second surface of the bracket body is recessed inwards to form a groove;

the first membrane is arranged on the first surface of the bracket body, the second membrane is arranged on the second surface of the bracket body, the first membrane and the second membrane are subjected to heat treatment to enable the first membrane and the second membrane to be fixed in an adhesive mode, and at least one of the first membrane and the second membrane is filled in the groove after heat treatment to obtain a connecting piece which is accommodated in and fixed to the groove.

Drawings

FIG. 1 is a schematic structural view of a prior art stent graft;

FIG. 2 is a schematic view of a part of the stent shown in FIG. 1;

FIG. 3 is a partial cross-sectional view of the stent graft of FIG. 2;

FIG. 4 is an enlarged view of a portion of FIG. 3;

FIG. 5 is a schematic view of the stent graft of FIG. 3 in a use configuration;

FIG. 6 is a schematic view of the stent graft of FIG. 3 in another use configuration;

FIG. 7 is a partial cross-sectional view of a stent graft of an embodiment;

FIG. 8 is a schematic view of the wave ring of the stent graft of FIG. 7;

FIG. 9 is an enlarged view of a portion of the wave ring of FIG. 8;

FIG. 10 is an enlarged view of a portion of a side bar of the wave band of FIG. 8;

FIG. 11 is a cross-sectional view of the sidebar of FIG. 10;

FIG. 12 is an enlarged view of a portion of the stent graft of FIG. 7;

FIG. 13 is a partial cross-sectional view of another embodiment of a stent graft;

FIG. 14 is a schematic view of the stent body of the stent graft of FIG. 13;

FIG. 15 is a schematic structural view of a stent graft according to yet another embodiment

FIG. 16 is a schematic view of the wave ring of the stent graft of FIG. 15;

FIG. 17 is a cross-sectional view of the wave ring of FIG. 16;

fig. 18 is a schematic structural view of the wave ring and the connecting member of the stent graft of fig. 15.

Detailed Description

In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," "upper," "lower," "far," "near," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to fig. 7 and 8, an exemplary stent graft 300 includes a stent body 310 and a stent graft 340.

The bracket body 310 includes a wave ring 312. The wave ring 312 is an alloy wire woven wave ring or a cut metal wave ring. In the illustrated embodiment, the eyelet 312 is braided from titanium-nickel alloy wire. The cross section of the wave ring 312 is circular.

In one embodiment, the stent body 310 is substantially cylindrical, and a plurality of wave rings 312 are spaced apart along the axial direction of the stent body 310. Of course, in other embodiments, the structure of the stand body 310 is not limited thereto. For example, the bracket body 310 further includes and connects a connecting rod (not shown) between two adjacent wave rings 312, and the two adjacent wave rings 312 are connected by at least one connecting rod. The spacing between the wave rings 312 is equal, but of course, the spacing between the wave rings 312 may be unequal.

In the illustrated embodiment, the band 312 is a Z-band. The band 312 includes peaks 3121, valleys 3123 and side bars 3125. The side bars 3125 connect adjacent peaks 3123 and valleys 3125.

The bracket body 310 has a first surface and a second surface opposite to the first surface. In the illustrated embodiment, the first surface refers to an outer surface of the stent body 310 and the second surface refers to an inner surface of the stent body 310.

The covering film 340 includes a first membrane 341, a second membrane 343, and a connecting member 345. The material of the cover 340 is expanded polytetrafluoroethylene. Preferably, the materials of the first membrane 341, the second membrane 343 and the connecting piece 345 are the same materials, so that the hot-melt adhesion of the covering film 340 is conveniently realized. Of course, in other embodiments, the materials of the first membrane 341, the second membrane 343 and the connecting member 345 can be fused and bonded together, and the melting points of the materials are close. It is understood that the connection member 345 may also be an encapsulation formed by an adhesive coated on the stent body 310 to increase the bonding strength of the stent body 310 and the cover 340. For example, the material of the connector 345 is Fluorinated Ethylene Propylene (FEP).

The first membrane 341 is disposed on the first surface of the bracket body 310, and the second membrane 343 is disposed on the second surface of the bracket body 310, so as to clamp the bracket body 310 and the connector 345 between the first membrane 341 and the second membrane 343. In the illustrated embodiment, the first membrane 341 and the second membrane 343 have the same thickness.

Referring also to fig. 9, the connector 345 is an envelope that encloses the collar 312. In the illustrated embodiment, the connector 345 is enveloped around a wire provided to the eyelet 312. The wire spirally wound around the eyelet 312 by the connector 345 forms an envelope to be secured to the eyelet 312. In the illustrated embodiment, the helically wound strips 3451 are flush, overlap-free and gapless, thereby ensuring that the formed envelope is smooth and free of protrusions. Thus, the connecting member 345 may be bonded to the first and second diaphragms 341, 343 by heat-fusing, the connecting member 345 being heat-fused to form an envelope around the collar 312. The number of the connection members 345 is not limited, and the envelope may be formed by winding one connection member 345 around the wave ring 312, or may be formed by winding a plurality of connection members 345 around the wave ring 312. It will be appreciated that in other embodiments, the wire may be inserted into the expanded polytetrafluoroethylene hose and the collar woven.

The thickness of the envelope formed by winding the collar 312 around the connector 345 affects the bonding strength between the bracket body 310 and the first and second diaphragms 341 and 343, and the greater the thickness of the envelope, the better the bonding strength between the envelope and the first and second diaphragms 341 and 343. Preferably, the ratio of the sum of the thicknesses of the first membrane 341 and the second membrane 343 to the thickness of the envelope is 4: 1-20: 1.

It should be noted that thicker envelopes will affect the compressive strength of the stent body 310. Therefore, it is preferable that the thickness of the envelope on the surfaces of the peaks 3121 and the valleys 3123 is smaller than the thickness of the envelope on the surface of the side bar 3125, so that the impact of the envelope on the compressive strength of the stent body 310 is reduced while the bonding strength of the envelope with the first membrane 341 and the second membrane 343 is ensured. The ratio of the thickness of the sum of the thicknesses of the first membrane 341 and the second membrane 343 to the thickness of the envelope on the surfaces of the peaks 3121 and the valleys 3123 is greater than 8:1, and the ratio of the thickness of the envelope on the surfaces of the side bars 3125 is 2:1 to 6:1. in one embodiment, the ratio of the thickness of the envelope at the peaks and troughs to the thickness of the envelope at the sidebar is 1:1.5 to 1:3. It will be appreciated that in one embodiment, the envelope may be provided only at the side bars of the wave band, with no envelope at the peaks and troughs of the wave band. It will also be appreciated that different thickness envelopes may be provided axially of the wire surface of the band 312 depending on the particular requirements for performance of the stent graft 300. It will also be appreciated that different coating thicknesses may also be provided in the circumferential direction of the wire of the band 312. For example, the thickness of the envelope at both sides of the wire of the wave band 312 is greater than the thickness at the first and second surfaces. The two side surfaces are surfaces perpendicular to the first surface and the second surface. Preferably, the ratio of the thickness of the envelope at both sides of the wire of the wave ring 312 to the distance between the first surface and the second surface of the wire is 2:1 to 4:1 to further increase the connection strength of the wire and the coating.

Referring to fig. 10 and 11, in the illustrated embodiment, the wire of the connecting piece 345 is spirally wound around the wave ring 312 to form a coating, gaps are formed between the strips formed by the spiral winding, the coating formed by the connecting piece 345 wrapping the wave ring covers part of the surface of the wave ring, and of course, when the gaps are smaller, the coating formed by the connecting piece 345 after hot melting can also completely cover the surface of the wave ring 312. Of course, the gap may be larger under certain conditions, and the connector 345 may form a discontinuous coating on the wire surface.

Referring to fig. 12, after the first membrane 341, the second membrane 343 and the connecting member 345 are bonded by a lamination process, the connecting member 345 is coated on the surface of the bracket body 310 by hot melting to form a coating, the connecting member 345 fills up the gap between the first membrane 341 and the second membrane 343, so that the bracket body 310 is fully fixed in the lamination 340, the connection strength between the bracket body 310 and the lamination 340 is greatly improved, and the stability and safety of the lamination bracket 300 are ensured.

According to the covered stent 300, under the action of external force, the stent body 310 is adhered and fixed with the first membrane 341 and the second membrane 343 through the connecting piece 345, so that looseness is not easy to occur between the first membrane 341 and the second membrane 343, and the risk of failure of the covered stent 300 caused by displacement of the stent body 310 when the covered stent 300 is stressed or deformed is reduced.

Referring to fig. 13 and 14, the structure of the stent graft 400 according to another embodiment is substantially the same as that of the stent graft 300, and the difference is that: the stent body 410 of the stent graft 400 is a cut metal stent, and the connecting members 445 are envelopes formed by coating layers coated on the surface of the stent body 410.

In the illustrated embodiment, the stent graft 400 is a stainless steel ball stent graft and the band 412 of the stent body 410 is a cut metal band made by metal laser engraving. The cross section of the wave ring 412 is rectangular. Preferably, the four corners of the rectangle are rounded.

In one embodiment, the attachment 445 is a coating formed by spraying, which adheres to the surface of the collar 412 to form an envelope. The material of the attachment 445 is preferably expanded polytetrafluoroethylene.

In one embodiment, the ratio of the sum of the thicknesses of the first diaphragm 441 and the second diaphragm 445 to the thickness of the envelope is 4: 1-20: 1.

In one embodiment, the thickness of the envelope of the surfaces of the crests 4121 and troughs 4123 is less than the thickness of the envelope of the surface of the side bar 3125. Preferably, the ratio of the sum of the thicknesses of the first diaphragm 341 and the second diaphragm 443 to the thickness of the coating on the surfaces of the peaks 4121 and the valleys 4123 is greater than 8:1, and the ratio of the sum of the thicknesses of the first diaphragm 441 and the second diaphragm 443 to the thickness of the coating on the surface of the side bar 4125 is 2:1 to 6:1.

In the film-covered stent 400, the connecting piece 445 is prepared by preparing the coating on the surface of the stent body 410, the first film 441, the second film 443 and the connecting piece 445 are subjected to hot melt adhesion, and then the connecting piece 445 is subjected to hot melt cladding on the surface of the stent body 410 to form the coating film, the connecting piece 445 fills the gap between the first film 441 and the second film 443, so that the stent body 410 is fully fixed in the film 440, the connection strength between the stent body 410 and the film 440 is greatly improved, and the stability and the safety of the film-covered stent 400 are ensured.

In the above-mentioned stent graft 400, under the action of external force, the stent body 410 is adhered and fixed to the first membrane 441 and the second membrane 443 by the connecting piece 445, so that the first membrane 441 and the second membrane 443 are not easy to loose, and the risk of failure of the stent graft 400 caused by displacement of the stent graft 410 when the stent graft 400 is stressed or deformed is reduced.

Referring to fig. 15 and 16, the structure of a stent graft 500 according to another embodiment is substantially the same as that of the stent graft 400, and the difference is that: the surface of the wave ring 512 of the stent graft 500 is formed with grooves 5121.

In the illustrated embodiment, the groove 5121 is formed by recessing inward from the first surface of the wave ring 512, although in other embodiments, the groove 5121 may be formed by recessing inward from the second surface of the wave ring 512, or both the first surface and the second surface of the wave ring 512 may be formed with grooves.

In the illustrated embodiment, the groove 5121 is a blind groove, although in other embodiments, the groove 5121 may be a through groove, and the groove 5121 extends through the first surface and the second surface.

Referring to fig. 15, 17 and 18, when the envelope surrounding the wave ring 512 is sprayed on the surface of the wave ring 512 as the connecting member 545, the coating material fills the groove 5121, so as to increase the adhesion between the connecting member 545 and the wave ring 512, the portion accommodated in the groove 5121 serves as an anchor point for connecting the connecting member 545 and the wave ring 512, and when the connecting member 545 is bonded to the first membrane 541 and the second membrane 543 by thermal fusion, the connection between the bracket body and the first membrane 541 and the second membrane 543 is more stable.

It is understood that the connection member 545 is not limited to the coating film of the coated wave ring 512 formed by spraying, and in other embodiments, the connection member 545 may be a coating film spirally wound around the wave ring 512, and in this case, after the coating film is subjected to hot pressing, the connection member 545, the first film 541 and the second film 543 may be hot-melted to fill the groove 5121. Of course, it is also understood that the coating applied to the wave ring 512 may be omitted, and after the film is hot-pressed, the first film 541 and the second film 543 are hot-melted and then filled in the groove 5121 to form a protrusion accommodated in the groove as a connecting piece, and at this time, the connecting piece is accommodated in and fixed to the groove, so as to become an anchor point for connecting the film and the wave ring 512. When the support body 510 is subjected to external force, the support body 510 is adhered and fixed with the first membrane 541 and the second membrane 543 through the connecting piece 545, so that looseness is not easy to occur between the first membrane 541 and the second membrane 543, and the risk of failure of the support 500 caused by displacement of the support body 510 when the support 500 is stressed or deformed is reduced.

The preparation method of the covered stent comprises the following steps:

Step S710, providing a bracket body.

The bracket body is provided with a first surface and a second surface opposite to the first surface. The bracket body comprises a wave ring.

In one embodiment, at least one of the first surface and the second surface of the bracket body is recessed inward to form a groove.

Step S720, forming a connecting piece wrapping the bracket body on the bracket body.

In one embodiment, the connector is wrapped around the stent body to form a coating around the stent body. Preferably, the connector is spirally wound around the wave ring. It is further preferred that the stripes formed by the connectors helically wound around the wave ring are flush, overlap-free and gapless to ensure that the envelope formed is smooth and free of protrusions. Of course, in other embodiments, gaps are formed between the stripes formed by the connection members spirally wound around the wave ring.

Further, the thickness of the connecting piece on the wave crest and the wave trough surface is smaller than that of the connecting piece on the side rod surface. It will be appreciated that in one embodiment, the connectors may be wrapped around only the side bars of the wave band and not around the peaks and valleys of the wave band.

In one embodiment, the connector is formed by forming a coating on the surface of the stent body. Preferably, the connection is obtained by spraying, spin coating or knife coating the slurry to form a coating. In one embodiment, the thickness of the coating on the peak and valley surfaces is less than the thickness of the coating on the side bar surfaces. It will be appreciated that in one embodiment, the coating may be applied only to the side bars of the wave band, with no coating at the peaks and valleys of the wave band. It will also be appreciated that different coating thicknesses may also be provided in the circumferential direction of the wave ring. For example, the thickness of the coating at the first and second surfaces is greater than the thickness at both sides of the wire of the wave ring. Preferably, the thickness of the coating at both sides of the bead wire is such that the ratio of the distance between the first surface and the second surface of the wire is 2:1 to 4:1.

In one embodiment, the connector is a hose sleeved on the wave ring of the bracket.

In one embodiment, the material of the connector is expanded polytetrafluoroethylene. In other embodiments, the material of the connector may also be an adhesive, such as Fluorinated Ethylene Propylene (FEP).

Step S730, the first membrane is disposed on the first surface of the support body, the second membrane is disposed on the second surface of the support body, and the first membrane and the second membrane are subjected to heat treatment to fix the first membrane and the second membrane by adhesion.

The first membrane and the second membrane are made of expanded polytetrafluoroethylene, and the first membrane, the second membrane and the connecting piece are made of the same materials. Of course, in other embodiments, at least one of the first membrane and the second membrane may be made of the same material as the connecting member. It is understood that when the material of the connecting member is an adhesive, the material of the connecting member may be different from the material of the first membrane and the second membrane.

In the step, the first membrane and the second membrane are subjected to heat treatment to enable the first membrane and the second membrane to be bonded in a hot-melting mode, and meanwhile the first membrane, the second membrane and the connecting piece are bonded in a hot-melting mode. Under the condition that the groove is formed on the surface of the bracket body, the connecting piece wound on the bracket body is subjected to hot melting to fill the groove.

The preparation method of the covered stent is simple to operate, and the prepared covered stent can improve the connection strength between the covered stent and the stent.

It is understood that the grooves on the surface of the stent body can be omitted, and the connection strength between the coating and the stent can be improved by directly forming the coating on the stent body. Step S720 may be omitted, in which a first membrane is directly disposed on a first surface of the bracket body having a groove on a surface, a second membrane is disposed on a second surface of the bracket body, and the first membrane and the second membrane are subjected to heat treatment to bond and fix the first membrane and the second membrane, at this time, at least one of the first membrane and the second membrane covered on the groove surface is melted and filled in the groove to obtain a connecting piece accommodated in and fixed to the groove. Of course, in order to better fill the groove, the surface of at least one of the first membrane and the second membrane may be disposed on the protrusion corresponding to the groove, and after the heat melting, the protrusion is accommodated in and fixed to the groove to form the connecting piece. It should be noted that the groove may be a through groove, penetrating through the first surface and the second surface of the wave ring, and filling the groove after the first membrane and the second membrane are hot melted to obtain a connecting piece fixedly connected with the first membrane and the second membrane at the same time.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (7)

1. The film covered bracket comprises a bracket body and a film covered, wherein the bracket body is provided with a first surface and a second surface opposite to the first surface, the film covered comprises a first film and a second film, the first film is arranged on the first surface, and the second film is arranged on the second surface and is adhered to the first film, and the film covered bracket is characterized by further comprising a connecting piece fixedly connected with the bracket body, the connecting piece is positioned between the first film and the second film, and the connecting piece is adhered to at least one of the first film and the second film;

The connecting piece is an envelope for wrapping the bracket body;

the ratio of the sum of the thicknesses of the first diaphragm and the second diaphragm to the thickness of the envelope is 4: 1-20: 1, a step of;

at least one of the first surface and the second surface is recessed inwards to form a groove, and the connecting piece is accommodated in and fixed to the groove.

2. The stent graft of claim 1, wherein said stent body comprises a band comprising peaks, valleys and side bars, said side bars connecting said peaks and valleys, the thickness of the envelope of said peaks and said valleys being less than the thickness of the envelope of said side bar surfaces.

3. The stent graft of claim 1, wherein the material of said connector is the same as the material of said first membrane sheet and/or said second membrane sheet.

4. The method for preparing the covered stent of claim 1, comprising the steps of:

Forming a connecting piece wrapping the bracket body on the bracket body; and the first membrane is arranged on the first surface of the bracket body, the second membrane is arranged on the second surface of the bracket body, and the first membrane and the second membrane are subjected to heat treatment so that the first membrane, the second membrane and the connecting piece are bonded and fixed.

5. The method for preparing a stent graft according to claim 4, wherein the step of forming a connecting member on the stent body to wrap the stent body comprises the steps of: and winding the connecting piece on the bracket body to form a coating wrapping the bracket body.

6. The method for preparing a stent graft according to claim 4, wherein the step of forming a connecting member on the stent body to wrap the stent body comprises the steps of: and forming a coating on the surface of the bracket body to obtain the connecting piece.

7. The method for preparing the covered stent of claim 1, comprising the steps of:

providing the bracket body, wherein at least one of the first surface and the second surface of the bracket body is recessed inwards to form a groove;

the first membrane is arranged on the first surface of the bracket body, the second membrane is arranged on the second surface of the bracket body, the first membrane and the second membrane are subjected to heat treatment to enable the first membrane and the second membrane to be fixed in an adhesive mode, and at least one of the first membrane and the second membrane is filled in the groove after heat treatment to obtain a connecting piece which is accommodated in and fixed to the groove.