CN116785023A

CN116785023A - Covered stent and suturing method thereof

Info

Publication number: CN116785023A
Application number: CN202210266472.6A
Authority: CN
Inventors: 李安伟; 孙孟孟
Original assignee: Hangzhou Wei Qiang Medical Technology Co ltd
Current assignee: Hangzhou Wei Qiang Medical Technology Co ltd
Priority date: 2022-03-17
Filing date: 2022-03-17
Publication date: 2023-09-22

Abstract

The invention relates to a covered stent and a sewing method thereof, wherein the covered stent comprises a covered film, a bare stent, a pre-buried line group and an envelope line group; the bare bracket is arranged on the outer side surface of the tectorial membrane; the embedded line group is arranged on the covering film along the outline of the bare bracket and comprises a plurality of embedded line segments arranged on the outer side surface of the covering film, and a gap is formed between each embedded line segment and the covering film; the envelope line group winds the bare bracket on each embedded line segment along the outline of the bare bracket. Because of the arrangement of the embedded line group, at least most of the suture lines can be fixed on the tectorial membrane by winding the bare stent and the embedded line segments, at least most of the suture lines do not need to penetrate through the tectorial membrane, the number of suture holes on the tectorial membrane is correspondingly reduced, and suture points are correspondingly reduced, so that the risk of internal leakage of the tectorial membrane stent is reduced, the inner wall of the tectorial membrane stent is smoother, and the risk of thrombus formation on the inner wall of the tectorial membrane stent after the tectorial membrane stent is implanted into a human blood vessel is reduced.

Description

Covered stent and suturing method thereof

Technical Field

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

Background

Cardiovascular and cerebrovascular diseases and peripheral vascular diseases seriously affect human health and even endanger life, and the most advanced and ideal treatment means at the present stage is interventional therapy. The interventional therapy is an emerging subject which adopts a minimally invasive method and combines medical imaging and clinical medicine to achieve the treatment effect, and has small trauma to patients and high safety.

For the interventional therapy of cardiovascular and cerebrovascular diseases and peripheral vascular diseases, a lumen stent is commonly used, and the lumen stent is conveyed to the focus position through a tiny wound or a natural lumen of a human body and then is released in an adjusting way. Most luminal stents include covered stents and bare stents, which refer to structures that include multiple wavy rings with no covering between each wavy ring. The covered stent is a structure of a bare stent covered with a covered film, the bare stent and a covered film material are stitched together by a suture line, the bare stent and the covered film material are conveyed to a vascular lesion position by a conveying catheter in a percutaneous puncture mode, and the covered film stent conveyed to the vascular lesion position plays a role in remodelling blood vessels.

However, current post-operative stent grafts have a certain chance of endoleak, which is typically caused by leakage of the stent material itself (gaps exist with the vessel wall), or by leakage through suture holes in the stent material. The reason for the internal leakage of the latter is mainly due to the problems of separation of the bare stent and the covered stent material, more suture holes, enlarged suture holes and the like, and the generation of the problems is closely related to the structure of the covered stent and the suture method of the covered stent.

Disclosure of Invention

The invention aims to provide a covered stent, which solves the problem of stent endoleak caused by leakage of suture holes in covered materials, so as to optimize the performance of the covered stent after suture to remodel a blood vessel and reduce the risk of endoleak of the covered stent implanted in the blood vessel.

Another object of the present invention is to provide a stent graft suturing method to optimize the performance of a sutured stent graft to remodel a blood vessel and reduce the risk of endoleak of an implanted stent graft.

According to one aspect of the present invention, there is provided a covered stent comprising a covered and a bare stent; the bare support is arranged on the outer side surface of the coating film; the embedded line group is arranged on the covering film along the outline of the bare bracket and comprises a plurality of embedded line segments arranged on the outer side surface of the covering film, and a gap is formed between each embedded line segment and the covering film; and the envelope line group winds the bare bracket on each embedded line segment along the outline of the bare bracket.

Preferably, the covering film is provided with a plurality of suture holes which are distributed at intervals along the outline of the bare bracket; the embedded line group penetrates through the sewing holes, and the embedded line segment is arranged between two adjacent sewing holes.

Preferably, the covered stent further comprises an inner membrane, wherein the inner membrane is arranged on the inner side surface of the covered membrane, and the inner membrane covers the suture hole.

Preferably, the embedded line group further comprises an embedded line segment which is arranged on the inner side surface of the covering film and positioned between two adjacent suture holes; the embedded line segments and the built-in line segments are alternately arranged to form continuous suture lines, and the suture lines alternately penetrate through a plurality of suture holes along the outline of the bare stent.

Preferably, the projection of the embedded line segment on the reference plane is not coincident with the projection of the embedded line segment on the reference plane; or the projection of the embedded line segment on the reference plane is overlapped with the projection part of the embedded line segment on the reference plane; the reference plane is an outer side surface or an inner side surface of the covering film when the covering film is in flat spreading.

Preferably, the bare bracket has alternately arranged wave crests and wave troughs, and the length value of the embedded line segments, which are arranged close to the wave crests and the wave troughs, in the embedded line group is smaller than the length value of the embedded line segments, which are arranged far away from the wave crests and the wave troughs, in the embedded line group.

Preferably, the bare stent has alternately arranged peaks and valleys, and the envelope group wraps the embedded line segments arranged near the peaks and valleys for a plurality of turns to form a plurality of envelope roots on the embedded line segments arranged near the peaks and valleys.

Preferably, the envelope group is a suture, the envelope group having a head end, a tail end, and an envelope segment connecting the head end and the tail end; the tail end is provided with a lantern ring, the lantern ring is sleeved on the initial section of the bare support and the embedded line groups, the enveloping section is wound and arranged on the bare support and each embedded line section along the outline of the bare support, and the head end penetrates through the initial section of the embedded line groups where the lantern ring is located and forms a fixed node.

According to another aspect of the present invention, there is provided a stent graft suturing method comprising the steps of:

arranging an embedded line group on the coating along the outline of the bare bracket, wherein the embedded line group comprises a plurality of embedded line segments positioned on the outer side surface of the coating, and a gap is formed between each embedded line segment and the coating;

and winding the bare bracket on each embedded line segment by utilizing a suture line along the outline of the bare bracket.

Preferably, the pre-buried line group is arranged on the covering film along the outline of the bare bracket, specifically: and (3) penetrating a suture line into the covering film along the outline of the bare stent and sewing the suture line on the covering film to form the embedded line group.

Preferably, the stitching thread penetrates through the covering film along the outline of the bare stent and is stitched on the covering film to form the embedded thread group, specifically: providing a continuous suture line in the length extension direction, alternately penetrating the suture line through a covering film along the outline of the bare stent to form the embedded line segment positioned on the outer side surface of the covering film and the built-in line segment positioned on the inner side surface of the covering film, wherein the embedded line segment and the built-in line segment form the embedded line group.

Preferably, in the step of forming the pre-buried string set, the suture thread is sewn to the cover film using a plain stitch method or a backstitch method.

Preferably, the bare bracket comprises a plurality of support rods connected in sequence at an angle, the support rods are connected end to end and form a wave structure, the support rods comprise a first side and a second side in the length direction, the bare bracket is wound on each embedded line segment by a suture line along the outline of the bare bracket, and the bare bracket specifically comprises: the suture line is driven by a needle rod to pass through a gap between the embedded line segment and the coating film from the first side of the supporting rod to the second side; enabling the needle bar to drive the suture line penetrating through the gap to wrap the support bar from the second side to the first side of the support bar; the above steps of passing the suture through the slit and wrapping the support bar are repeated along the contour of the bare stent.

Preferably, the bare bracket comprises a plurality of support rods connected in sequence at an angle, the support rods are connected end to end and form a wave structure, the support rods comprise a first side and a second side in the length direction, the bare bracket is wound on each embedded line segment by a suture line along the outline of the bare bracket, and the bare bracket specifically comprises: the needle bar is utilized to drive the suture line to wrap the support bar from the first side to the second side of the support bar; the suture thread surrounding the supporting rod is driven by the needle rod to pass through a gap between the embedded line segment and the coating film from the second side of the supporting rod to the first side; the above steps of wrapping the suture around the support bar and passing through the slit are repeated along the contour of the bare stent.

Preferably, the suturing method of the covered stent further comprises the following steps:

fixing the tail end of the suture line on the tectorial membrane/bare bracket/embedded line segment to form an initial fixing position;

the head end of the suture is fixed to the covered/bare stent/pre-buried wire segment to form a termination fixation site.

Preferably, the tail end of the suture is fixed on the covered film/bare stent/embedded line segment to form an initial fixed position, specifically: and a needle rod connected with the suture head end is used for outputting a needle from the inner side surface of the covering film to the outer side surface of the covering film from the first side of the supporting rod, and the tail end of the suture is fixed and then limited on the inner side surface of the covering film.

Preferably, the tail end of the suture is fixed on the covered film/bare stent/embedded line segment to form an initial fixed position, specifically: the tail end of the suture is provided with a collar, the suture is wound on the bare bracket and the initial embedded line segment at least one circle by using a needle bar connected with the head end of the suture, the needle bar penetrates through the collar, the suture is tensioned, and the bare bracket is fixed on the initial embedded line segment by the collar to form the initial fixed position.

Preferably, the head end of the suture is fixed to the covered/bare stent/pre-buried wire segment to form a termination fixation site, specifically: after the naked bracket is wound on each embedded line segment along the outline of the naked bracket by using a suture, the head end of the suture is driven by a needle rod to penetrate out of a gap between the initial embedded line segment and the coating film and is fixed to be a limiting part.

Preferably, the bare bracket has alternately arranged wave crests and wave troughs, and in the step of arranging the embedded line group, the length value of the embedded line segments arranged close to the wave crests and the wave troughs is smaller than the length value of the embedded line segments arranged far away from the wave crests and the wave troughs.

Preferably, in the step of winding the bare stent around each of the pre-buried wire segments along the contour of the bare stent with a suture, the suture is made to wrap the same pre-buried wire segment around a plurality of turns in at least a part of the pre-buried wire segments to form a plurality of envelope roots.

Preferably, the bare stent has alternately arranged peaks and valleys, and in the step of winding the bare stent around each of the pre-buried wire segments along the contour of the bare stent using a suture, the pre-buried wire segments near the peaks and valleys are wrapped around a plurality of turns using the suture to form a plurality of envelope roots at the pre-buried wire segments near the peaks and valleys.

As can be seen from the technical scheme, the embodiment of the invention has at least the following advantages and positive effects:

in the process of preparing the covered stent by using the suturing method provided by the embodiment of the invention, the embedded line groups are preset along the outline of the bare stent on one side of the covered stent close to the bare stent, so that a plurality of suturing nodes can be preformed on one side of the covered stent close to the bare stent, and the suturing nodes can be understood as the gap space between each embedded line segment in the embedded line groups and the covered stent. Based on this, in the follow-up sewing process, the seam can pass the gap space between each pre-buried line segment and the tectorial membrane and/or pass the gap space between the bare bracket and the tectorial membrane along the profile sequence of bare bracket to the seam can twine bare bracket and each pre-buried line segment each other along the profile of bare bracket, will greatly improve the sewing efficiency of support like this. In addition, due to the arrangement of the embedded line group, at least most of the suture thread can be fixed on the tectorial membrane by winding the bare stent and the embedded line segment, at least most of the suture thread does not need to penetrate through the tectorial membrane, the number of suture holes on the tectorial membrane is correspondingly reduced, and suture points are correspondingly reduced, so that the risk of internal leakage of the tectorial membrane stent prepared by the suture method is reduced, the inner wall of the tectorial membrane stent is smoother, and the risk of thrombus formation on the inner wall of the tectorial membrane stent after the tectorial membrane stent is implanted into a human blood vessel is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

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

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

FIG. 3 is a schematic view of a partial enlarged structure at A in the stent graft shown in FIG. 2;

FIG. 4 is a flow chart of the preparation of the stent graft shown in FIG. 2;

FIG. 5 is a schematic view of a partial structure of a side of the inner wall of the stent graft shown in FIG. 2;

FIG. 6 is a schematic view of a partial structure of a bare stent sewn to a stent according to the stent shown in FIG. 2;

FIG. 7 is a schematic structural view of a stent graft according to an embodiment of the present invention;

FIG. 8 is a schematic view of a part of the stent graft shown in FIG. 7 at B;

FIG. 9 is a schematic view of the stent graft shown in FIG. 7 without an envelope group;

FIG. 10 is a schematic view of a structure of a stent graft without an envelope curve set according to another embodiment;

FIG. 11 is a schematic view of a partially enlarged structure of a stent graft according to another embodiment of the present invention;

FIG. 12 is a schematic view of the structure of the stent graft of the present invention after the free ends of the envelope curve sets are knotted;

FIG. 13 is a schematic flow chart of a suturing method for a covered stent provided by the invention;

FIGS. 14-18 are flowcharts of suture preparation for a stent graft according to an embodiment of the present invention;

FIGS. 19-21 are flowcharts of suture preparation for a stent graft according to another embodiment of the present invention.

The reference numerals are explained as follows: 1,2, a tectorial membrane bracket; 11 A bare stent, 21; 12 22, coating; 13 20, suture; 14 30, a needle bar; 131. an intersection; 121 221, suture holes; 110 210, support bars; 1101 2101, first side; 1102 2102, second side; 111. a protrusion; 211. a peak; 212. a trough; 23. embedding a line group; 231. pre-burying line segments; 231a, a start section; 233. a built-in line segment; 24. envelope groups; 241. envelope root; 24a, a head end; 24b, tail end; 24c, an envelope segment; 242. a collar; 244. a node;

Detailed Description

For the covered stent, the proximal end refers to the end of the covered stent, which is close to the heart of the human body after the covered stent is used for interventional therapy, and the distal end refers to the end of the covered stent, which is far away from the heart of the human body after the covered stent is used for interventional therapy.

Prior art stent grafts have a certain probability of endoleak, which is typically caused by leakage of the stent material itself (gaps exist with the vessel wall), or by leakage through suture holes in the stent material. The leakage caused by the suture holes in the tectorial membrane material is mainly due to the problems of separation of the bare stent and the tectorial membrane, more suture holes, enlarged suture holes and the like, and the generation of the problems is closely related to the suture structure and the suture method of the tectorial membrane stent.

For an easy understanding of the reasons for the above problems with prior art stent grafts, please see below.

Referring to fig. 1 and 2, a related art stent graft 1 includes a bare stent 11, a stent graft 12, and a suture 13, and the bare stent 11 is suture-fixed to the stent graft 12 by the suture 13. The number of the bare stents 11 is at least one, and the number of the bare stents 11 is plural as illustrated in fig. 1, and the plurality of bare stents 11 are arranged at intervals along the axial direction of the stent graft 1. The bare stent 11 comprises a plurality of support struts 110 connected in angular sequence. By "angularly connected" is meant interconnected and forming an included angle greater than 0 degrees and less than 180 degrees. The plurality of support rods 110 are sequentially connected to form a wave form having undulation, so that the bare stent 11 can be contracted or expanded in the radial direction. Among the included angles formed by any two adjacent support rods 110 in each bare stent 11, the included angle near the proximal end of the covered stent 1 forms a peak, and the included angle near the distal end of the covered stent 1 forms a trough.

Referring to fig. 3, the cover 12 is positioned inside or outside the bare stent 11, and the suture lines 13 alternately penetrate the cover 12 along both sides of the outline of the bare stent 11 to suture the bare stent 11 on the cover 12. In the suturing method of the stent graft 1 in the prior art, the conventional cross puncture suturing method, the so-called "cross puncture suturing method", is that the suture thread 13 is alternately threaded on two sides of the length direction of the support rod 110 by manual or machine operation to suture the bare stent 11 on the stent graft 12, and because the suture holes are distributed on the stent graft 12 on two sides of the length direction of the support rod 110 along the outline of the bare stent 11, and because the direction of the puncture force in the suturing process is mostly pulled in multiple directions, the diameter of the suture holes on the stent graft 12 is generally larger than the diameter of the suture thread 13, and the larger number of suture holes with larger diameter are very easy to cause the occurrence of internal leakage of the stent graft 1.

Referring to fig. 4, fig. 4A to 4E in fig. 4 are schematic views illustrating a suturing process of the prior art stent graft 1. For convenience of distinction, both sides of the support bar 110 in the length direction are respectively designated as a first side 1101 and a second side 1102. Specifically, step one: referring to fig. 4A, a needle bar 14 connected to the head end of the suture thread 13 is withdrawn from the first side 1101 of the support bar 110 (the withdrawn needle is that the needle bar 14 drives the suture thread 13 to pierce the covering film 12 from the inner side surface of the covering film 12 to penetrate the outer side surface of the covering film 12, the inner side surface is that side of the covering film bracket 1 through which blood flows, and the outer side surface is that side of the covering film bracket 1 which is in contact with the blood vessel wall), and the tail end of the suture thread 13 is knotted and then limited to the inner side surface of the covering film 12; step two: referring to fig. 4B, the needle bar 14 carries the suture thread 13 around the support bar 110 from the first side 1101 to the second side 1102 of the support bar 110 (the needle carrying means that the needle bar 14 carries the suture thread 13 to pierce the covering film 12 from the outer side of the covering film 12 to penetrate the inner side of the covering film 12; the wrapping means that the suture thread 13 contacts with the side of the support bar 110 away from the inner side of the covering film 1, thereby fixing the bare stent 11 on the covering film 12) to fix the bare stent 11 on the covering film 12; step three: referring to fig. 4C, the needle bar 14 drives the suture thread 13 to be withdrawn from the first side 1101 of the support bar 110, and the needle bar 14 is inserted through a gap formed between the suture thread 13 and the support bar 110 when withdrawn; step four: referring to fig. 4D, the suture 13 is pulled by an external force, so that the suture 13 is crossed to form a crossing point 131; step four: referring to fig. 4E, steps two to four are repeated along the outline of the bare stent 11 to form a plurality of crossing points 131, thereby firmly fixing the bare stent 11 to the covering film 12.

As is clear from the suturing step of fig. 4, in order to promote a better fit between the bare stent 11 and the covering film 12, the sutures 13 used in the suturing process often intersect each other to form a plurality of intersecting points 131. However, an increased number of crossing points 131 may cause a certain stimulation of the vessel wall, which may have unexpected consequences, for example, which may lead to damage of the vessel wall or thrombus formation.

Referring to fig. 5, fig. 5 illustrates a schematic partial structure of the inner side of the stent graft 1, and the stent graft 1 is manufactured by the above-mentioned prior art sewing method. Two groups of continuous suture holes 121 are formed on both sides of the support bar 110 along the outline of the bare stent 11 on the inner side surface of the stent graft 1, and the two suture holes 121 opposite to both sides of the support bar 110 are connected by a section of suture 13. Because of this, a large number of suture holes 121 easily cause leakage in the stent graft 1, and the presence of the suture thread 13 connecting the two suture holes 121 to the inner wall of the stent graft 1 will make the inner wall of the stent graft 1 uneven, which is easy to form thrombus.

Referring to fig. 6, fig. 6 illustrates a partial structure of the support bar 110 of the stent graft 1 sewn to the stent graft 12. The above prior art suturing method is used to tightly fix the covering film 12 and the supporting rod 110 together, and the supporting rod 110 presses the covering film 12 on the side close to the covering film 12, so that the protrusions 111 are formed on the inner side surface of the covering film bracket 1, and blood is easy to form thrombus at the protrusions 111 to damage the body of a patient.

In summary, in order to overcome the problems that the covered stent 1 prepared by adopting the suturing method in the prior art leaks in the vessel after being implanted, thrombus is easy to form on the inner wall of the covered stent, the invention provides the covered stent and the suturing method thereof.

First, referring to fig. 7, the present invention provides a stent graft 2, where the stent graft 2 includes a bare stent 21, a stent graft 22, a pre-buried wire set 23 and an envelope set 24. The bare stent 21 is sewn and fixed to the outer peripheral surface of the covering film 22 by the pre-buried wire group 23 and the envelope wire group 24. The bare stent 21 comprises a plurality of support struts 210 connected in angular sequence. By "angularly connected" is meant interconnected and forming an included angle greater than 0 degrees and less than 180 degrees. The plurality of support rods 210 are sequentially connected to form a wave shape having undulation, so that the bare stent 21 can be contracted or expanded in the radial direction. Among the angles formed by any two adjacent support rods 210 in each bare stent 21, the angle near the proximal end of the stent graft 2 forms a peak, and the angle near the distal end of the stent graft 2 forms a trough.

The bare stent 21 may be made of one or more of nickel-titanium alloy, nickel-titanium super elastic alloy, cobalt-chromium-nickel-molybdenum alloy, copper-based shape memory alloy, iron-based shape memory alloy, medical stainless steel alloy, various polymers (e.g., polynorbornene, polyurethane, polylactic acid copolymer, etc.), and the like. The above materials have high elasticity and shape memory characteristics, and thus the bare stent 21 can be contracted in the radial direction and can be restored to its original shape. The cover film 22 may be formed of any suitable cover film material including, but not limited to: low porosity woven or knitted polyester, dacron material, expanded polytetrafluoroethylene, polyurethane, silicone, ultra high molecular weight polyethylene, or other suitable material. The pre-buried line group 23 and the envelope line group 24 can be medical sutures, preferably polymer sutures, and the polymer sutures can be PTFE or PET sutures.

The embedded wire group 23 is fixedly connected to the covering film 22 along the outline of the bare stent 21. The embedded line group 23 comprises a plurality of embedded line segments 231 arranged on the outer side surface of the covering film 12, and a gap for allowing the suture to pass is formed between each embedded line segment 231 and the covering film 22. That is, the two ends of the embedded line segment 231 are connected to the coating film 22, and the middle of the embedded line segment 231 is not connected to the coating film 22.

In an embodiment, referring to fig. 8, the covering film 22 is provided with a plurality of stitching holes 221 penetrating through both inner and outer sides of the covering film 22 and arranged at intervals along the outline of the bare stent 21, the pre-buried line group 23 is penetrated through the stitching holes 221, and the pre-buried line segment 231 is disposed between two adjacent stitching holes 221.

A plurality of pre-buried line segments 231 are provided for obtaining the outer layer of the coating 22. Referring to fig. 9, the pre-buried wire group 23 is a continuous suture thread which is alternately penetrated through the plurality of suture holes 221 along the contour of the bare stent 21 to suture and fix the bare stent 21 to the cover film 22.

Specifically, fig. 9 illustrates that the suture is stitched on the covering film 22 by a full-loop stitching method, at this time, a plurality of pre-buried line segments 231 formed on the outer side surface of the covering film 22 by a stitching process of the full-loop stitching are arranged at intervals along the length direction of the supporting rod 210, and the plurality of pre-buried line segments 231 on the outer side surface of the covering film 22 are generally in an end-to-end line shape. It should be appreciated that in other embodiments, the suture may be sewn to the covering film 22 by a half-loop sewing process to form the embedded line segments 231, and at this time, the plurality of embedded line segments 231 formed on the outer side surface of the covering film 22 are arranged at intervals along the length direction of the supporting rod 210.

It should be noted that, in the sewing process of the suture thread, whether a full-loop stitch or a half-loop stitch is adopted, the suture thread forms a plurality of embedded line segments 231 on the outer side surface of the covering film 22, and simultaneously, the suture thread forms a plurality of built-in line segments (not shown) on the inner side surface of the covering film 22, the built-in line segments are located between two adjacent suture holes 221, and the built-in line segments and the embedded line segments 231 are alternately arranged in a linear manner along the outline of the embedded line group 23. The projection of the embedded line segment 231 on the reference plane coincides with the projection of the built-in line segment on the reference plane, and the reference plane can be understood as the outer side or the inner side of the coating film 22 when it is spread.

In other embodiments, referring to fig. 10, fig. 10 illustrates that the suture thread is sewn on the covering film 22 by a flat stitch, and the embedded thread group 23 is a continuous suture thread, at this time, a plurality of embedded thread segments 231 formed on the outer side surface of the covering film 22 are arranged at intervals along the length direction of the supporting rod 210. Note that, in the suture thread using the sewing process of the flat stitch, the suture thread forms a plurality of embedded line segments 231 on the outer side surface of the cover film 22, and simultaneously forms a plurality of built-in line segments 233 on the inner side surface of the cover film 22 (the broken line is schematically shown in fig. 10, the broken line indicates that the built-in line segments 233 are located on the inner side surface of the cover film 22), the built-in line segments 233 are located between two adjacent suture holes 221, and the built-in line segments 233 and the embedded line segments 231 are alternately arranged in a linear manner along the outline of the embedded line group 23. In addition, in the sewing process using the flat stitch, the projection of the pre-embedded line segment 231 on the reference plane does not coincide with the projection of the built-in line segment 233 on the reference plane, and the reference plane may be understood as the outer side or the inner side of the covering film 22 when it is spread in a flat state.

The embedded line groups 23 may be discontinuous sutures, that is, the embedded line segments 231 in the embedded line groups 23 are independent of each other, and two ends of each embedded line segment 231 pass through two adjacent suture holes 221 and are knotted, at this time, the embedded line groups 23 do not include the embedded line segments 233, that is, the embedded line groups 23 can be formed by a plurality of embedded line segments 231.

In an embodiment, the stent graft 2 may further include at least one inner membrane (not shown) disposed on the inner side of the stent graft 22 and covering the suture holes 221 and the inner line segment 233, i.e., the inner line segment 233 is disposed between the stent graft 22 and the inner membrane. At this time, the inner membrane and the covering membrane 22 are combined to form a multi-layer thin film structure, the inner membrane is used for avoiding the generation of inner leakage of the covering membrane bracket 2 by covering the stitching hole 221, the inner side surface of the covering membrane bracket 2 can be smoother by covering the inner line segment 233, the inner side surface of the covering membrane bracket 2 is prevented from being uneven due to the inner line segment 233, and the risk of thrombus generation can be reduced.

Note that, the formation of the embedded line segment 231 is not limited to the above-described form in which the suture hole 221 is provided in the coating film 22, without considering the difficulty of manufacturing or processing the coating film 22 by the embedded line group 23. For example, two ends of the embedded wire segment 231 may be adhered to the covering film 22, and the embedded wire group 23 may be a continuous suture line, where a plurality of spaced adhesion fixing points are provided along the outline of the bare stent 21, and an area between two adjacent adhesion fixing points may be regarded as the embedded wire segment 231. Alternatively, the pre-buried wire set 23 may include a plurality of independent pre-buried wire segments 231, where the plurality of independent pre-buried wire segments 231 are disposed along the outline of the bare stent 21, and both ends of each pre-buried wire segment 231 are adhered to the covering film 22.

With continued reference to fig. 7 and 8, the envelope curve set 24 may be understood as a continuous or discontinuous suture, and the envelope curve set 24 winds the bare stent 21 around each pre-buried line segment 231 along the contour of the bare stent 21. Specifically, the envelope curve group 24 sequentially passes through the gap space between each embedded line segment 231 and the covering film 22 and/or passes through the gap space between the bare stent 21 and the covering film 22 along the outline of the bare stent 21, and after the envelope curve group 24 passes through the two spaces, the envelope curve group 24 reversely wraps the bare stent 21 and the embedded line segments 231, so that the envelope curve group 24 can wind the bare stent 21 and each embedded line segment 231 along the outline of the bare stent 21, and the stent sewing efficiency is also improved during specific sewing. Of course, instead of sequentially passing through each pre-embedded line segment 231 along the contour of the bare stent 21, the envelope set 24 may also pass through a portion of the pre-embedded line segments 231 along the contour of the bare stent 21 to implement skip stitching.

Note that, in the envelope group 24 of the present embodiment, the embedded line segments 231 disposed near the peaks 211 and the valleys 212 are wrapped around a plurality of circles to form a plurality of envelope roots 241 on the embedded line segments 231 disposed near the peaks 211 and the valleys 212. For example, fig. 7 and 8 illustrate that the envelope group 24 wraps the pre-buried line segment 231 disposed near the peaks 211 and the valleys 212 two times, thereby forming two envelope roots 241 on the pre-buried line segment 231 disposed near the peaks 211 and the valleys 212. Since the bare stent 21 is stressed more at the peaks 211 and the troughs 212, the bare stent 21 at the position is easy to separate from the covering film 22, so the suturing strength of the bare stent 21 and the covering film 22 can be improved based on the increase of the number of the envelope curve roots 241. It will be appreciated that in other embodiments, the envelope group 24 wraps each pre-buried wire segment 231 one or more turns to form one or more envelope roots 241, regardless of the suture strength of the bare stent 21 and the covering film 22.

In addition, in the present embodiment, the length value of each of the embedded line segments 231 in the embedded line group 23 is equal. It will be appreciated that in other embodiments, referring to fig. 11, fig. 11 illustrates only one peak 211 of the bare stent 21, and the peak and trough are the same but not illustrated, and the length of the embedded line segment 231 of the embedded line set 23 disposed near the peak 211 and the trough 212 is smaller than the length of the embedded line segment 231 of the embedded line set 23 disposed far from the peak 211 and the trough 212. This can be also understood that, at the positions where the forces such as the peaks 211 and the valleys 212 are larger, the needle pitch of the pre-buried line segment 231 is smaller, so as to ensure the stitching strength of the positions where the peaks 211 and the valleys 212 are located of the bare stent 21, and avoid the separation of the bare stent 21 from the coating film 22 at the positions where the peaks 211 and the valleys 212 are located. The stress at the wave waist position is smaller, the needle distance of the pre-buried line segment 231 is larger, and the sewing process can be simplified.

Due to the arrangement of the embedded wire group 23, at least most of the suture (the suture is used for forming the envelope wire group 24 after the bare stent 21 and the embedded wire segment 231 are wound) only needs to be wound around the bare stent 21 and the embedded wire segment 231, the bare stent 21 can be fixed on the tectorial membrane 22, at least most of the suture does not need to penetrate through the tectorial membrane 22, the number of suture holes 221 on the tectorial membrane 22 is correspondingly reduced, and suture points are correspondingly reduced, so that the risk of internal leakage of the tectorial membrane stent 2 is reduced, the inner wall of the tectorial membrane stent 2 is smoother, and the risk of thrombus formation on the inner wall of the tectorial membrane stent 2 after the tectorial membrane stent 2 is implanted into a human blood vessel is reduced.

It should be emphasized that with reference to fig. 12, the suture used to form envelope segment 24 has a leading end 24a, a trailing end 24b, and an envelope segment 24c connecting leading end 24a and trailing end 24b, where at least a majority of the suture need not penetrate through cover 22, it is understood that some portions of the suture may still penetrate through the cover, such as where the free ends of the suture in its length extension (i.e., leading end 24a and trailing end 24b of the suture) penetrate through cover 22 and are constrained to cover 22, such as where leading end 24a and trailing end 24b are constrained to cover 22 by knotting to form a junction. However, in this embodiment, both the leading end 24a and the trailing end 24b of the suture may be restrained without penetrating the covering film 22, so that the number of openings on the covering film 22 may be reduced.

For the purpose of reducing the openings of the cover film 22. In this embodiment, referring to fig. 12, a collar 242 is disposed at the tail end of the suture, the collar 242 is sleeved on the initial section 231a of the bare stent 21 and the embedded wire set 23, and the envelope section 24c winds the bare stent 21 and each embedded wire segment 231 along the outline of the bare stent 21, and after winding the envelope section 24c for one round, the head end 24a of the suture can pass through the initial section 231a of the embedded wire set 23 where the collar 242 is located and form a node 244.

The above description of the stent graft 2 provided by the present invention also provides a suturing method of the stent graft 2 in order to obtain the stent graft 2 of each of the above embodiments.

First embodiment of method for suturing covered stent

Referring to fig. 13, the suturing method of the covered stent 2 comprises the following steps:

step S10, arranging an embedded line group on the covering film along the outline of the bare bracket, wherein the embedded line group comprises a plurality of embedded line segments positioned on the outer side surface of the covering film, and a gap is formed between each embedded line segment and the covering film.

Step S20, fixing the tail end of the suture line on the covering film to form an initial fixing position.

And S30, winding the bare stent on each embedded line segment by utilizing a suture line along the outline of the bare stent.

Step S40, fixing the head end of the suture line to the covering film to form a termination fixing position.

In step S10, in order to obtain the embedded wire group 23, referring to fig. 14, a suture thread is inserted through the cover film 22 along the outline of the bare stent 21 and is sewn to the cover film 22 to form the embedded wire group 23. Specifically, the present embodiment provides a continuous suture in the length extending direction, and the suture is alternately threaded through the covering film 22 along the outline of the bare stent 21 to form a pre-embedded line segment 231 located on the outer side surface of the covering film 22 and a built-in line segment located on the inner side surface of the covering film 22, where the pre-embedded line segment 231 and the built-in line segment form the pre-embedded line set 23.

The sewing process for sewing the seam on the covering film 22 to form the embedded thread group 23 can be concretely a plain stitch sewing method or a backstitch sewing method. The backstitch stitching method includes a full backstitch stitching method and a half backstitch stitching method, and the present invention is described in detail in the foregoing structural description of the covered stent 2, and is not repeated here.

In other embodiments, the pre-buried wire set 23 may be formed by bonding a suture to the covering film 22, and the specific implementation of the suture-bonding covering film 22 is described above, which is not repeated herein. The description will be made herein with respect to a scheme in which a suture thread penetrates the cover film 22 and is sewn to the cover film 22 to form the embedded thread group 23.

In addition, the bare stent 21 has alternately arranged peaks 211 and valleys 212, and in the step of arranging the embedded wire group 23, the length value of the embedded wire segment 231 arranged near the peaks 211 and valleys 212 may be made smaller than the length value of the embedded wire segment 231 arranged far from the peaks 211 and valleys 212. The different length settings of the pre-buried line segment 231 at different positions are also described in detail above, and are not described here again.

In step S20, the bare stent 21 includes a plurality of support rods 210 connected in sequence at an angle, the plurality of support rods 210 are connected end to end and form a wave structure, the support rods 210 include a first side 2101 and a second side 2102 in the length direction thereof, referring to fig. 15, in order to tie a knot (the knot may be understood as a knot herein, or may be understood as a sintering or other limiting structure, that is, the outer diameter of the end of the suture 20 is larger than the outer diameter of the suture hole to fix the suture 20 to the covering film 22), a needle rod 30 connected to the end 24a of the suture 20 may be needled from the inner side 2101 of the support rod 210 toward the outer side of the covering film 22 from the inner side of the covering film 22, and the tail end of the suture 20 may be limited to the inner side of the covering film 22 after the knot. It will be appreciated that the tail end 24b of the suture 20 may also be tied to the bare stent 21 or the pre-buried wire segment 231. For example, the tail end of the suture 20 may be wrapped around the bare stent 21 or the pre-buried wire segment 231 to achieve tail end containment.

In step S30, step S30 may specifically include the steps of:

in step S31a, referring to fig. 16, the needle bar 30 is used to drive the suture thread 20 to sequentially pass through the gap between the support bar 210 and the coating film 2 and the gap between the pre-buried line segment 231 and the coating film (the gap between the initial pre-buried line segment 231a and the coating film 22) from the first side 2101 of the support bar 210 to the second side 2102.

In step S32a, referring to fig. 17, the needle bar 30 is caused to drive the suture thread 20 passing through the slit to wrap around the support bar 210 from the second side 2102 to the first side 2101 of the support bar 210.

Step S33a, referring to fig. 18, the steps S31a and S32a are repeated along the outline of the bare stent 21, so as to wind the bare stent 21 around each pre-embedded line segment 231, thereby fixing the bare stent 21 and the covering film 22 relatively.

If the length direction of the support rod 210 is parallel to and spaced apart from the length direction of the embedded line segment 231, the suture thread 20 needs to sequentially pass through the gap between the support rod 210 and the coating film 2 and the gap between the embedded line segment 231 and the coating film 22 in step S31 a. If the support bar 210 is attached to/located above the pre-buried line segment, i.e., the support bar 210 is located on the side of the pre-buried line segment 231 away from the covering film 22, the suture 20 only needs to pass through the gap between the pre-buried line segment 231 and the covering film 22.

In other embodiments, step S30 may also include the following steps (not shown):

in step S31b, the suture thread 20 is driven by the needle bar 30 from the first side 2101 of the support bar 210 to the second side 2102 by wrapping the support bar 210 from the side of the support bar 210 facing away from the inner side of the covering film 22.

In step S32b, the needle bar 30 drives the suture thread 20 to sequentially pass through the gap between the pre-buried line segment 231 and the coating film 22 (the gap between the initial pre-buried line segment 231a and the coating film 22) and the gap between the support bar 210 and the coating film 22 from the second side 2102 of the support bar 210 to the second side 2102.

Step S33b, repeating step S31b and step S32b along the outline of the bare stent 21, so as to wind the bare stent 21 around each embedded line segment 231, thereby realizing the relative fixation of the bare stent 21 and the covering film 22.

If the length direction of the support bar 210 is parallel to and spaced apart from the length direction of the pre-buried line segment 231, in step S32b, the suture thread 20 needs to sequentially pass through the gap between the pre-buried line segment 231 and the coating film 22 and the gap between the support bar 210 and the coating film 2. If the support bar 210 is attached to/located above the pre-buried line segment, i.e., the support bar 210 is located on the side of the pre-buried line segment 231 away from the covering film 22, the suture 20 only needs to pass through the gap between the pre-buried line segment 231 and the covering film 22.

In step S30, the suture thread 20 may be wrapped around the same embedded line segment 231 in at least a portion of the embedded line segments 231 according to actual requirements, so as to form a plurality of envelope roots 241. For example, the pre-buried line segments 231 near the peaks 211 and the valleys 212 may be wrapped multiple times with the suture 20 to form a plurality of envelope roots 241 at the pre-buried line segments 231 near the peaks 211 and the valleys 212. The number of the envelope roots 241 is plural and is described in detail above, and will not be described here.

In step S40, the head end 24a of the suture thread 20 is tied to the cover film 22 to form a termination fixation site. Specifically, after the bare stent 21 is wound around each pre-buried line segment 231 along the outline of the bare stent 21 by using the suture thread 20, the needle bar 30 connected with the head end 24a of the suture thread 20 may be used to drive the suture thread 20 to insert the needle (the insertion is that the needle bar 30 drives the suture thread 20 to pierce the covering film 22 from the outer side surface of the covering film 22 to the inner side surface of the penetrating covering film 22), so that the head end 24a of the suture thread 20 is knotted and limited to the inner side surface of the covering film 22 after the insertion. It will be appreciated that the head end 24a of the suture 20 may also be tied to the bare stent 21 or the pre-buried wire segment 231. For example, the head end 24a of the suture 20 may be wrapped around the bare stent 21 or the pre-buried wire segment 231 to achieve containment of the head end 24a of the suture 20.

The above suturing method for the stent graft has the advantage that in the process of preparing the stent graft 2 by using the suturing method according to the embodiment of the present invention, since the pre-buried line group 23 is provided in advance along the outline of the bare stent 21 at the side of the stent graft 22 close to the bare stent 21, a plurality of suturing nodes can be formed in advance at the side of the stent graft 22 close to the bare stent 21, and the plurality of suturing nodes can be understood as a gap space between each pre-buried line segment 231 in the pre-buried line group 23 and the stent graft 22. Based on this, in the subsequent sewing process, the suture thread 20 sequentially passes through the gap space between each pre-buried line segment 231 and the cover film 22 and the gap space between the bare stent 21 and the cover film 22 along the outline of the bare stent 21, so that the suture thread 20 can intertwine the bare stent 21 and each pre-buried line segment 231 along the outline of the bare stent 21, which greatly improves the sewing efficiency of the stent. In addition, due to the arrangement of the embedded wire group 23, at least most of the suture thread 20 only needs to be wound around the bare stent 1 and the embedded wire segment 231, the bare stent 21 can be fixed on the tectorial membrane 22, at least most of the suture thread 20 does not need to penetrate through the tectorial membrane 22, the number of suture holes 221 on the tectorial membrane 22 is correspondingly reduced, and suture points are correspondingly reduced, so that the risk of internal leakage of the tectorial membrane stent 2 prepared by the suture method is reduced, the inner wall of the tectorial membrane stent 2 is smoother, and the risk of thrombus formation on the inner wall of the tectorial membrane stent 2 after the tectorial membrane stent 2 is implanted into a human blood vessel is reduced.

Second embodiment of the covered stent suturing method

Referring to fig. 19 to 21, another embodiment of the present invention provides a suturing method of a stent graft 2, which is substantially the same as that of the first embodiment, except that the tail end 24b of the suture thread 20 is knotted, and the head end 24a of the suture thread 20 is knotted, that is, the step S20 and the step S40 are different.

In step S20 of the present embodiment, step S20 may specifically include the following steps:

in step S21, referring to fig. 19, a collar 242 is disposed at the tail end 24b of the suture thread 20, the collar 242 may be a circular ring or a non-circular ring, and the needle bar 30 is passed through the collar 242 after the suture thread 20 is wound around the bare stent 21 and the initial pre-embedded line segment 231a at least once by using the needle bar 30 connected to the head end 24a of the suture thread 20.

In step S22, referring to fig. 20, the suture thread 20 is tightened, so that the bare stent 21 is fixed to the initial pre-buried line segment 231a by the collar 242, forming an initial fixing position. At this time, the tail end 24b of the suture 20 is fixed relative to the bare stent 21 and the embedded wire segment 231. The knotting method of the present embodiment can avoid the perforation of the covering film 22.

After performing step S20 of the present embodiment, step S30 may be continuously performed, that is, the bare stent 21 is wound around each pre-buried wire segment 231 with the suture thread 20 along the contour of the bare stent 21. Referring to fig. 21, the suture thread 20 may be stitched to each pre-buried line segment 231 by the needle bar 30, which will not be described herein.

In step S40 of the present embodiment, step S40 may be specifically implemented by referring to fig. 12, after step S30, that is, after the bare stent 21 is wound around each pre-embedded line segment 231 along the outline of the bare stent 21 by using the suture thread 20, the head end 24a of the suture thread 20 may be penetrated out of the gap between the initial pre-embedded line segment 231a and the covering film 22 by using the needle bar 30 and knotted to form a knot (limit portion) 244.

While the invention has been described with reference to several exemplary embodiments, it is to be understood that the terminology used is intended to be in the nature of words of description and of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.

Claims

1. A stent graft, comprising:

coating a film;

the bare bracket is arranged on the outer side surface of the coating film;

the embedded line group is arranged on the covering film along the outline of the bare bracket and comprises a plurality of embedded line segments arranged on the outer side surface of the covering film, and a gap is formed between each embedded line segment and the covering film;

And the envelope line group winds the bare bracket on each embedded line segment along the outline of the bare bracket.

2. The stent graft of claim 1, wherein said stent graft is provided with a plurality of suture holes spaced along the contour of said bare stent; the embedded line group penetrates through the sewing holes, and the embedded line segment is arranged between two adjacent sewing holes.

3. The stent graft of claim 2, further comprising an inner membrane disposed on an inner side of said membrane, said inner membrane covering said suture holes.

4. The stent graft of claim 2, wherein said pre-buried wire set further comprises a built-in wire segment disposed on an inside surface of said stent graft and between two adjacent said suture holes;

the embedded line segments and the built-in line segments are alternately arranged to form continuous suture lines, and the suture lines alternately penetrate through a plurality of suture holes along the outline of the bare stent.

5. The stent graft of claim 4, wherein the projection of said pre-embedded line segment on the reference plane does not coincide with the projection of said built-in line segment on the reference plane; or the projection of the embedded line segment on the reference plane is overlapped with the projection part of the embedded line segment on the reference plane;

The reference plane is an outer side surface or an inner side surface of the covering film when the covering film is in flat spreading.

6. The stent graft of claim 1, wherein the bare stent has alternating peaks and valleys, and wherein the length of the pre-buried line segments of the pre-buried line set that are disposed proximate to the peaks and valleys is less than the length of the pre-buried line segments of the pre-buried line set that are disposed distal to the peaks and valleys.

7. The stent graft of claim 1, wherein the bare stent has alternating peaks and valleys, and wherein the set of envelopes wraps around pre-buried line segments disposed proximate the peaks and valleys for a plurality of turns to form a plurality of envelope roots on the pre-buried line segments disposed proximate the peaks and valleys.

8. The stent graft of claim 1, wherein said envelope curve set is a suture, said envelope curve set having a head end, a tail end, and an envelope segment connecting said head end and said tail end; the tail end is provided with a lantern ring, the lantern ring is sleeved on the initial section of the bare support and the embedded line groups, the enveloping section is wound and arranged on the bare support and each embedded line section along the outline of the bare support, and the head end penetrates through the initial section of the embedded line groups where the lantern ring is located and forms a fixed node.

9. The suturing method of the covered stent is characterized by comprising the following steps:

10. The suturing method of the covered stent according to claim 9, wherein the arranging of the pre-buried wire group along the outline of the bare stent on the covered stent comprises:

and (3) penetrating a suture line into the covering film along the outline of the bare stent and sewing the suture line on the covering film to form the embedded line group.

11. The method for suturing a covered stent according to claim 10, wherein the steps of threading a suture through a covered film along a bare stent contour and suturing the suture to the covered film to form the embedded wire group are as follows:

providing a continuous suture line in the length extension direction, alternately penetrating the suture line through a covering film along the outline of the bare stent to form the embedded line segment positioned on the outer side surface of the covering film and the built-in line segment positioned on the inner side surface of the covering film, wherein the embedded line segment and the built-in line segment form the embedded line group.

12. The stent graft stitching method according to claim 11, wherein in the step of forming the pre-buried thread group, the stitching thread is stitched to the stent graft using a plain stitch method or a backstitch method.

13. The stent graft stitching method according to claim 9, wherein the bare stent comprises a plurality of struts connected in angular sequence, the struts being connected end-to-end and forming a wave-shaped configuration, the struts comprising a first side and a second side along a length thereof, the bare stent being wrapped around each of the pre-embedded wire segments with stitching along the contour of the bare stent, comprising:

the suture line is driven by a needle rod to pass through a gap between the embedded line segment and the coating film from the first side of the supporting rod to the second side;

enabling the needle bar to drive the suture line penetrating through the gap to wrap the support bar from the second side to the first side of the support bar;

the above steps of passing the suture through the slit and wrapping the support bar are repeated along the contour of the bare stent.

14. The stent graft stitching method according to claim 9, wherein the bare stent comprises a plurality of struts connected in angular sequence, the struts being connected end-to-end and forming a wave-shaped configuration, the struts comprising a first side and a second side along a length thereof, the bare stent being wrapped around each of the pre-embedded wire segments with stitching along the contour of the bare stent, comprising:

The needle bar is utilized to drive the suture line to wrap the support bar from the first side to the second side of the support bar;

the suture thread surrounding the supporting rod is driven by the needle rod to pass through a gap between the embedded line segment and the coating film from the second side of the supporting rod to the first side;

the above steps of wrapping the suture around the support bar and passing through the slit are repeated along the contour of the bare stent.

15. The stent graft suturing method of claim 13 or 14, wherein the stent graft suturing method further comprises the steps of:

16. The stent graft suture method of claim 15, wherein the tail end of the suture is fixed to the stent graft/bare stent/pre-embedded wire segment to form an initial fixation site, specifically:

and a needle rod connected with the suture head end is used for outputting a needle from the inner side surface of the covering film to the outer side surface of the covering film from the first side of the supporting rod, and the tail end of the suture is fixed and then limited on the inner side surface of the covering film.

17. The stent graft suture method of claim 15, wherein the tail end of the suture is fixed to the stent graft/bare stent/pre-embedded wire segment to form an initial fixation site, specifically:

the tail end of the suture is provided with a collar, the suture is wound on the bare bracket and the initial embedded line segment at least one circle by using a needle bar connected with the head end of the suture, the needle bar penetrates through the collar, the suture is tensioned, and the bare bracket is fixed on the initial embedded line segment by the collar to form the initial fixed position.

18. The stent graft suture method of claim 17, wherein the suture head is fixed to the stent graft/bare stent/pre-embedded wire segment to form a stop fixation site, in particular:

after the naked bracket is wound on each embedded line segment along the outline of the naked bracket by using a suture, the head end of the suture is driven by a needle rod to penetrate out of a gap between the initial embedded line segment and the coating film and is fixed to be a limiting part.

19. The stent graft stitching method according to claim 9, wherein the bare stent has alternating peaks and troughs, and wherein in the step of providing the pre-buried wire set, the length of the pre-buried wire segment positioned adjacent the peaks and troughs is less than the length of the pre-buried wire segment positioned away from the peaks and troughs.

20. The stent graft suturing method of claim 9, wherein in the step of wrapping the bare stent around each of the pre-buried wire segments with a suture along the contour of the bare stent, the suture is wrapped around the same pre-buried wire segment a plurality of times in at least a portion of the pre-buried wire segments to form a plurality of envelope roots.

21. The stent graft stitching method according to claim 20, wherein the bare stent has alternating peaks and troughs, and wherein in the step of wrapping the bare stent around each of the pre-buried wire segments with a stitch line along the contour of the bare stent, the pre-buried wire segments adjacent the peaks and troughs are wrapped multiple times with the stitch line to form multiple envelope roots at the pre-buried wire segments adjacent the peaks and troughs.