Patent Description:
Over the past decade, endovascular stent-grafts for aortic dissections have been widely used in lesions such as thoracic and abdominal aortic aneurysms and arterial dissections, and have become a first-line treatment with definite efficacy, less trauma, faster recovery and fewer complications. However, for special lesions such as aortic arch, celiac trunk, bilateral renal artery or superior mesenteric artery, the use of stent grafts can affect the blood supply to the arterial branch vessels. In view of this situation, the stent graft is usually opened in situ by laser or mechanical means during the operation, so that the stent graft produces an expected hole, and then the branch stent is transported to the hole and docked with the stent graft. Such therapeutic regimen overcomes the dependence on the anatomical structure of human branch vessels.

In the prior art, when a stent graft is opened in situ, there are often problems that the window size is difficult to meet the requirements, or the window edge support is poor.

<CIT> discloses a stent graft. A body of the stent graft comprises a plurality of wavy supporting rings which are arrayed to form a tubular structure. At least one supporting ring is a multi-wave ring. The multi-wave ring comprises a first wave and a second wave which are connected. The stent graft has the advantages that in the endovascular repair treatment process of aortic dissection involving arch, the second wave of the multi-wave ring minimizes the gap between the aorta body stent graft and a chimney graft, the body stent graft can better wrap the chimney graft, and the endoleak occurrence rate is decreased; the first wave of the multi-wave ring makes the radial acting force of the body stent graft on the chimney graft within the fatigue strength range of the chimney graft, the pressure stress of a pipe wall can not be excessively increased, and meanwhile the chimney graft is prevented from being blocked; the small amplitude of the first wave and the large amplitude of the second wave make the stent graft fit the bend of the aortic arch.

<CIT> discloses an endoluminal prosthesis including a tubular graft having a proximal end and a distal end; a suprarenal spring stent operably connected to the proximal end, the suprarenal spring stent having suprarenal positive apices and suprarenal negative apices connected in a sinusoidal ring pattern by suprarenal struts; and a sealing spring stent operably connected to the tubular graft, the sealing spring stent having sealing positive apices, sealing negative apices, and intermediate sealing negative apices connected in a ring pattern, the sealing negative apices alternating with the intermediate sealing negative apices between adjacent sealing positive apices, the sealing positive apices being connected to the sealing negative apices by sealing struts, and the sealing positive apices being connected to the intermediate sealing negative apices by intermediate sealing struts. The suprarenal positive apices are axially aligned with the intermediate sealing negative apices.

<CIT> discloses a stent comprises at least one curve deployment section. The at least one curve deployment section comprises at least one expansion ring having a circumferential length, a longitudinal length and comprising a first circumferential section and a second circumferential section. The first circumferential section comprises an expansion column and the second circumferential section comprises at least two expansion columns longitudinally offset from one another. The expansion column of the first circumferential section is engaged to the at least two expansion columns of the second circumferential section.

<CIT> discloses an intravascular stent assembly for implantation in a body vessel, such as a coronary artery, includes undulating circumferential rings having peaks on the proximal end and valleys on the distal end. Adjacent rings are coupled together by links. The rings and links are arranged so that the stent has good conformability as it traverses through, or is deployed in, a tortuous body lumen. The stent is also configured such that the likelihood of peaks and valleys on adjacent rings which point directly at each other to overlap in tortuous body vessels is reduced.

The present application is to provide a stent graft suitable for in-situ fenestration to overcome the defects in the prior art.

In order to overcome the defects in the prior art, the technical solution of the application is as follows:
Provided is a stent graft, including a plurality of wavy rings. The stent graft includes, in a circumferential direction, a region A and a region B connected with the region A; each wavy ring includes first wavy segments located in the region A and second wavy segments located in the region B; region A being for fenestration; the ratio of a wave height of the first wavy segment to a spacing between the adjacent first wavy segments ranges from <NUM>/<NUM> to <NUM>; a wave included angle of each second wavy segment is <NUM>°-<NUM>°; the ratio of a wave height of the second wavy segment to a spacing between the adjacent second wavy segments is <NUM>/<NUM>-<NUM>/<NUM>; and the ratio of the wave height of the first wavy segment to the wave height of the second wavy segment is greater than or equal to <NUM>/<NUM> and less than <NUM>; characterized in that a wave included angle (α) of each first wavy segment ranges from <NUM>° to <NUM>°.

In the stent graft of the present application, the region A includes a greater curvature side region and a lesser curvature side region that are distributed in the circumferential direction, the wave included angle of the greater curvature side region is <NUM>°-<NUM>°, and the wave included angle of the lesser curvature side region is <NUM>°-<NUM>°.

In the stent graft of the present application, the ratio of the wave height of the first wavy segment in the greater curvature side region to the wave height of the first wavy segment in the lesser curvature side region is <NUM>-<NUM>.

In the stent graft of the present application, the ratio of the wave spacing between the adjacent first wavy segments in the greater curvature side region to the wave spacing between the adjacent first wavy segments in the lesser curvature side region is <NUM>-<NUM>.

In the stent graft of the present application, the greater curvature side region and the lesser curvature side region are symmetrically disposed in the circumferential direction, and the region B is located between the greater curvature side region and the lesser curvature side region.

In the stent graft of the present application, the ratio of the area covered by the greater curvature side region on an outer surface of the stent graft to the area covered by the lesser curvature side region on the outer surface of the stent graft is <NUM>-<NUM>.

In the stent graft of the present application, the included angle of the region B in the circumferential direction is <NUM>°-<NUM>°.

In the stent graft of the present application, when a connecting line between a wave crest of the first wavy segment and a corresponding wave crest of the adjacent first wavy segment is parallel to a busbar of the stent graft, the value of L1/L2 is greater than or equal to <NUM>/<NUM> and less than or equal to <NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>.

In the stent graft of the present application, when a connecting line between the wave crest of the first wavy segment and a corresponding wave trough of the adjacent first wavy segment is parallel to the busbar of the stent graft, the value of L1/L2 is greater than or equal to <NUM>/<NUM> and less than or equal to <NUM>/<NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>.

In the stent graft of the present application, the wave height of the first wavy segment is <NUM>-<NUM>, and the wave height of the second wavy segment is <NUM>-<NUM>.

In conclusion, the stent graft for in-situ fenestration of the application has the following beneficial effects that according to the application, with the arrangement of the region A and the region B with different wave included angles in the circumferential direction of the stent graft, and the adjustment on the ratio of the wave height of the region A to the wave height of the region B, the region A can meet the requirements of fenestration, and the region B can meet the requirement of axial supporting force, so that the stent graft is prevented from shortening into a tumor cavity. In addition, by adjusting the ratio of the wave height to the wave spacing of the region A and the ratio of the wave height to the wave spacing of the region B, the requirements of fenestration can be well met in each position of the region A, the adaptability of the stent graft is improved, and meanwhile, the situation that the bending property of the stent graft in the position is affected due to dense distribution of local waves in the region A and the region B, or the situation that the stent graft is prone to deformation due to poor the supporting effect of the stent graft in the position caused by sparse distribution of local waves in the region A and the region B, is avoided.

The application will be further described in combination with accompanying drawings and embodiments. In drawings:.

In order that the technical features, objects and effects of the present application may be more clearly understood, specific embodiments thereof will now be described in detail with reference to the accompanying drawings.

It should be noted that "distal" and "proximal" are used as orientation words, which are customary terms in the field of interventional medical apparatuses, wherein the "distal" means an end away from an operator during a surgical procedure, and the "proximal" means an end close to the operator during the surgical procedure. An axial direction refers to a direction which is parallel to the connecting line of a distal center and a proximal center of a medical apparatus; a radial direction refers to a direction perpendicular to the axial direction; and the distance from the axis refers to the distance reaching the axis in the radial direction.

As shown in <FIG>, a first exemplary embodiment of the present application provides a stent graft which is substantially of an open-ended and hollow tubular structure, the stent graft including a plurality of wavy rings <NUM>, and covering membranes <NUM> fixed to the plurality of the wavy rings <NUM> to connect the plurality of the wavy rings <NUM>.

The covering membranes <NUM> are substantially of middle-closed and open-ended tube cavity structures and made of high molecular materials having good biocompatibility, such as e-PTFE, PET, or the like. The covering membranes <NUM> are fixed to the plurality of wavy rings <NUM> and enclosed to form a tube cavity with a longitudinal axis, and the tube cavity serves as a channel through which blood flows when the stent graft is implanted in a blood vessel.

The wavy rings <NUM> are made of materials with good biocompatibility, such as nickel titanium, stainless steel, or the like. The plurality of wavy rings <NUM> are arranged sequentially from a proximal end to a distal end, such as arranged in a parallelly spaced manner. The embodiment does not limit a specific arrangement of the plurality of wavy rings <NUM>, and the plurality of wavy rings <NUM> may be connected into a mesh-like structure. Each wavy ring <NUM> is a closed cylindrical structure, and includes a plurality of proximal vertexes <NUM>, a plurality of distal vertexes <NUM>, and supporting bodies <NUM> connecting the adjacent proximal vertexes <NUM> and distal vertexes <NUM>, and the proximal vertexes <NUM> and distal vertexes <NUM> are wave crests and troughs of corresponding waves, respectively. The plurality of wavy rings <NUM> have the same or similar wavy shapes, for example, the wavy rings <NUM> may be of Z-shaped wave, M-shaped wave, V-shaped wave or sinusoidal wave structures, or of other structures that are radially compressible to a small diameter.

The stent graft may be prepared as follows: weaving a metal wire into a required wave shape, wherein the metal wire may be a nickel-titanium alloy wire with a wire diameter of, for example, <NUM>; and after heat setting, sleeving two end portions of the metal wire with a steel jacket and fixing by mechanical pressing so that the metal wire and the steel jacket are connected and fastened to form a metal ring. After all the wavy rings <NUM> are manufactured, surfaces of the wavy rings <NUM> which are sequentially arranged are covered with membranes. For example, inner surfaces and outer surfaces of the plurality of wavy rings <NUM> may be integrally covered with e-PTFE membranes, the plurality of wavy rings <NUM> are located between two covering membranes <NUM>, and the e-PTFE covering membranes of an inner layer and an outer layer are bonded together by high-temperature pressing, thereby fixing the plurality of wavy rings <NUM> between the two covering membranes. In other embodiments, the wavy rings <NUM> may also be sutured to PET membranes.

Of course, when formed by integrally cutting a metal tube, the wavy rings <NUM> are not required to be fixedly connected by the steel jacket. Alternatively, the wavy ring may be formed by welding two end points of the metal wire.

Referring to <FIG>, the stent graft includes, in a circumferential direction, a region A and a region B connected with the region A, where a region surrounded by dotted lines in <FIG> is the region B. The wavy ring <NUM> includes first wavy segments located in the region A and second wavy segments located in the region B, wherein a wave included angle α of each first wavy segment is <NUM>°-<NUM>°; the ratio of a wave height L1 of the first wavy segment to a spacing L2 between the adjacent first wavy segments is <NUM>/<NUM>-<NUM>; a wave included angle α of the second wavy segment is <NUM>°-<NUM>°; the ratio of a wave height L3 of the second wavy segment to a spacing L4 between the adjacent second wavy segments is <NUM>/<NUM>-<NUM>/<NUM>; and the ratio of the wave height L1 of the first wavy segment to the wave height L3 of the second wavy segment is greater than or equal to <NUM>/<NUM> and less than <NUM>. The wave included angle α refers to an included angle between supporting bodies <NUM> connected to two sides of the same proximal vertex <NUM> or the distal vertex <NUM>.

When in-situ fenestration is carried out on the stent graft, a puncture component is used to puncture a small hole in the stent graft, and the small hole is dilated to a required size by the use of a balloon. Referring to <FIG>, the wave heights of the wavy rings <NUM> in <FIG> are the same, and the wave included angles are <NUM>°, <NUM>° and <NUM>°, respectively. A balloon with a diameter of D1 (such as D1 being <NUM>-<NUM>) is used to expand a circle of the same size in the corresponding position of each wavy ring <NUM>, wherein the corresponding position refers to a position where the distance of a connecting line between the circle center of the balloon and a proximal vertex of the wavy ring <NUM> in each of <FIG> in the axis direction of the stent graft is equal. The hatched lines in the figures indicate the shapes of windows expanded by the balloon, and it can be seen from the figures that when the wave included angle is <NUM>° or <NUM>°, the windows meeting the size requirements may be expanded, while the wavy ring <NUM> with the wave included angle being <NUM>° may limit the fenestration size so that a fenestration edge follows the wavy ring <NUM>. In the figures, the region of the wavy ring <NUM> covered by a circle with a diameter of D2 (D2=<NUM>%D1) is a region where the wavy ring <NUM> supports the fenestration edge, that is, the greater the corresponding angle δ of an intersection of the wavy ring <NUM> and the circle with the diameter of D2 is, the higher the supporting effect that the wavy ring <NUM> provides for the fenestration edge is. As can be seen from the figures, the larger the wave included angle is, the smaller the corresponding angle δ of the intersection of the wavy ring <NUM> and the circle with the diameter of D2 is, leading to a failure to provide sufficient support for the fenestration edge by the wavy ring <NUM>.

As can be seen from the above, when the wave included angle of the wavy ring <NUM> in a certain region is large, the wavy ring <NUM> does not limit the fenestration size, thereby being beneficial to the fenestration; however, if the wave included angle is too large, the fenestration edge is caused to be far away from the wavy ring <NUM>, and the wavy ring <NUM> cannot provide enough support for the fenestration edge; and if the fenestration edge lacks the support from the wavy ring <NUM>, the window may be further expanded under the action of radial force of a branch stent, finally leading to the separation of the branch stent from the stent graft. In addition, if the wave included angle of the wavy ring <NUM> is too large, the number of waves distributed in the circumferential direction of the stent graft in the region is too small, which is not conducive to maintaining the tube cavity shape of the stent graft. However, when the wave included angle of the wavy ring <NUM> in a certain region is small, although enough support may be provided for the fenestration edge, the fenestration size may be limited, resulting in that the fenestration size hardly meets the size of a branch vessel. In addition, the wavy ring <NUM> has certain rigidity and is not prone to deformation under the action of external force, and after a fenestration component is abutted against the wavy ring <NUM>, the wavy ring <NUM> is easily broken or the wavy ring <NUM> is excessively displaced with respect to the covering membrane <NUM>, so that the radial supporting effect of the stent graft is affected.

According to the application, with the arrangement of the region A and the region B with different wave included angles in the circumferential direction of the stent graft, and the adjustment on the ratio of the wave height of the region A to the wave height of the region B, the region A can meet the requirements of fenestration, and the region B can meet the requirement of axial supporting force, so that the stent graft is prevented from shortening into a tumor cavity. In addition, by adjusting the ratio of the wave height to the wave spacing of the region A and the ratio of the wave height to the wave spacing of the region B, the requirements of fenestration can be well met at each position of the region A, the adaptability of the stent graft is improved, and meanwhile, the situation that the bending property of the stent graft at the position is affected due to dense distribution of local waves in the region A and the region B, or the situation that the stent graft is prone to deformation due to poor the supporting effect of the stent graft in the position caused by sparse distribution of local waves in the region A and the region B, is avoided.

Referring to <FIG>, the first wavy segment includes a plurality of first proximal vertexes 102a, a plurality of first distal vertexes 103a, and first supporting bodies 104a connecting the adjacent first proximal vertexes 102a and first distal vertexes 103a. The second wavy segment includes at least one second proximal vertex 102b, at least one second distal vertex 103b, and a second supporting body 104b connecting the adjacent second proximal vertex 102b and second distal vertex 103b. Where, the wave height L1 of the first wavy segment refers to the distance in the axial direction between the first proximal vertex 102a and the first distal vertex 103a, and the spacing L2 between the adjacent first wavy segments is the distance in the axial direction between the first proximal vertex 102a on the first wavy segment and the first proximal vertex 102a on the adjacent first wavy segment. The wave height L3 of the second wavy segment refers to the distance in the axial direction between the second proximal vertex 102b and the second distal vertex 103b, and the spacing L4 of the adjacent second wavy segments is the distance in the axial direction between the second proximal vertex 102b on the second wavy segment and the second proximal vertex 102b on the adjacent second wavy segment. In the illustrated embodiment, the first distal vertex 103a and the second distal vertex 103b are located in the same plane perpendicular to the longitudinal central axis of the stent graft.

When the wave height of the wavy ring <NUM> is too low, not only the wave processing is not facilitated, but also the radial supporting effect of the stent graft is poor; and when the wave height of the wavy ring <NUM> is too high, the deformation resistance of the stent graft is poor, and the stent graft is prone to folding. Therefore, L1 and L3 meet the conditions that L1 is greater than or equal to <NUM> and less than or equal to <NUM> and L3 is greater than or equal to <NUM> and less than or equal to <NUM>. For example, L1 is greater than or equal to <NUM> and less than or equal to <NUM>, and L3 is greater than or equal to <NUM> and less than or equal to <NUM>.

A plurality of first wavy segments in the region A are arranged in a spaced manner in the axial direction, and when the adjacent first wavy segments are different in phase, the areas for fenestration between the adjacent first wavy segments are different. <FIG> are sequentially schematic diagrams of the adjacent first wavy segments being opposite in phase, being identical in phase, and having a phase difference, in the case that the wave structures and wave spacings of the adjacent first wavy segments are identical when the adjacent first wavy segments have no overlap in the axial direction. The being opposite in phase means that the wave crests of the first wavy segment are opposite to the wave troughs of the adjacent first wavy segment, the being identical in phase means that the wave crests of the first wavy segment are opposite to the wave crests of the adjacent first wavy segment, and the phase difference means that the wave crests of the first wavy segment are staggered with the wave crests and troughs of the adjacent first wavy segment. It can be seen from the figures that when the adjacent first wavy segments are opposite in phase, the area available for fenestration between the adjacent first wavy segments is maximum, and when the adjacent first wavy segments are identical in phase, the area available for fenestration is minimum. However, when the adjacent first wavy segments are identical in phase, the distribution of a fenestration region is relatively uniform.

In order to meet the fenestration requirement of the stent graft, different phase conditions can be adapted by adjusting the wave height of the first wavy segment and the ratio of the wave height to the wave spacing. In the case that the adjacent first wavy segments have no overlap in the axial direction, when the connecting line between the wave crest of the first wavy segment and the corresponding wave crest of the adjacent first wavy segment is parallel to the busbar of the stent graft, the value of L1/L2 is greater than or equal to <NUM>/<NUM> and less than or equal to <NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>; when the connecting line between the wave crest of the first wavy segment and the corresponding wave trough of the adjacent first wavy segment is parallel to the busbar of the stent graft, the value of L1/L2 is greater than or equal to <NUM>/<NUM> and less than or equal to <NUM>/<NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>; and when the connecting line between the wave crest of the first wavy segment and the corresponding wave crest of the adjacent first wavy segment is inclined with respect to the busbar of the stent graft, and the connecting line between the wave trough of the first wavy segment and the corresponding wave trough of the adjacent first wavy segment is also inclined with respect to the busbar of the stent graft, the value of L1/L2 is greater than or equal to <NUM>/<NUM> and less than or equal to <NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>. As shown in conjunction with <FIG>, in the case that the adjacent first wavy segments have overlaps in the axial direction, the value of L1/L2 is greater than <NUM> and less than or equal to <NUM>, and L1 is greater than or equal to <NUM> and less than or equal to <NUM>. The corresponding wave crest here refers to a wave crest of the adjacent first wavy segment, having the shortest connecting distance between which and the wave crest of the first wavy segment than other wave crests of the adjacent first wavy segment; and the corresponding wave trough here refers to a wave trough of the adjacent first wavy segment, having the shortest connecting distance between which and the wave trough of the first wavy segment than other wave troughs of the adjacent first wavy segment.

As shown in <FIG> and <FIG>, the region A includes two sub-regions, namely a greater curvature side region 100a and a lesser curvature side region 100b, that are distributed in the circumferential direction. Where, the wave included angle of the greater curvature side region 100a is <NUM>°-<NUM>°, such as <NUM>°, and the wave included angle of the lesser curvature side region 100b is <NUM>°-<NUM>°, such as <NUM>°. The ratio of the wave height of the first wavy segment in the greater curvature side region 100a to the wave height of the first wavy segment in the lesser curvature side region 100b is about <NUM>-<NUM>, the ratio of the wave spacing between the adjacent first wavy segments in the greater curvature side region 100a to the wave spacing between the adjacent first wavy segments in the lesser curvature side region 100b is <NUM>-<NUM>, and the ratio of the area covered by the greater curvature side region 100a on the outer surface of the stent graft to the area covered by the lesser curvature side region 100b on the outer surface of the stent graft is <NUM>-<NUM>. In the illustrated embodiment, the ratio of the area covered by the greater curvature side region 100a on the outer surface of the stent graft is equal to the area covered by the lesser curvature side region 100b on the outer surface of the stent graft, the wave heights of the first wavy segments in the greater curvature side region 100a are equal, and the wave spacings between the adjacent first wavy segments in the greater curvature side region 100a are equal. Also, the wave heights of the first wavy segments in the lesser curvature side region 100b are equal, and the wave spacings between the adjacent first wavy segments in the lesser curvature side region 100b are equal.

In the illustrated embodiment, the greater curvature side region 100a and the lesser curvature side region 100b are disposed oppositely in the circumferential direction, and the region B is connected between the greater curvature side region 100a and the lesser curvature side region 100b. It will be appreciated that the region A may also include three or more circumferentially distributed sub-regions as desired, the sub-regions may be arranged in a spaced manner or continuously, and the wave shapes, the number of waves, the wave heights, and the wave angles of the wavy segments of each sub-region may be set as desired.

Further, the axial shortening rate of the region B is less than the axial shortening rate of the region A, and the axial shortening rate of the stent graft in the region B is <NUM>%-<NUM>%.

A method for calculating the shortening rate of the stent graft in the axial direction is as follows: taking the length of the stent graft, which is in a straight tube shape, in the axial direction in a natural state as r and the diameter of the stent graft as d1, sleeving an inner tube with the diameter of d2 (d2 is less than d1, for example, d2 is equal to <NUM>%*d1) with the stent graft, applying pressure F (1N≤F≤2N) in the axial direction to the stent graft till the stent graft cannot shorten anymore to obtain the total length s, and calculating the axial shortening rate of the stent graft in the region B according to the formula (r-s)/r× <NUM>%. Where, the value of (r-s) is an available maximum shortening value of the stent graft. The stent graft sleeves the inner tube for shortening, so that the phenomenon that the stent graft is folded when shortening can be effectively avoided, that is, the value of (r-s) of the present application is the available maximum shortening value when the stent graft is not folded.

When the stent graft is in a frustum shape, that is, the diameters of the two ends of the stent graft are different, the length of the stent graft in the axial direction in the natural state is r, the diameter of the large end is d1, the diameter of the small end is d3, the stent graft sleeves a conical inner tube or a frustum inner tube with the same taper as the stent graft, and the perpendicular distance between the stent graft and the conical inner tube or the frustum inner tube is <NUM>. The position of the small end of the stent graft is fixed and unchanged, the pressure F (1N≤F≤2N) in the axial direction is applied to the large end, and the total length of the stent graft when the stent graft cannot shorten anymore is s, and thus the shortening rate of the stent graft in the axial direction is (r-s)/r <NUM>%. Where, the value of (r-s) is an available maximum shortening value of the stent graft. The stent graft sleeves the inner tube for shortening, so that the phenomenon that the stent graft is folded when shortening can be effectively avoided, that is, the value of (r-s) of the present application is the available maximum shortening value when the stent graft is not folded.

When the stent graft itself is manufactured into a bent shape, as shown in <FIG>, the stent graft includes a first bent section 400a and a second bent section 400b, the first bent section 400a has a first profile line 401a on a greater curvature side of the first bent section 400a and a second profile line 402a on a lesser curvature side of the first bent section 400a, and the second bent section 400b has a third profile line 401b on a greater curvature side of the second bent section 400b and a fourth profile line 402b on a lesser curvature side of the second bent section 400b. At this time, there are two methods for calculating the shortening rate of the bent section of the stent graft. One method is as follows: referring to <FIG> together, by taking the first bent section 400a as an example, partitioning the first bent section 400a with a plane <NUM> perpendicular to the axial direction of the stent graft; cutting a plurality of notches <NUM> in the covering membranes <NUM> close to the second profile line 402a, wherein the sizes of the notches <NUM> can ensure that the stent graft is straightened along the first profile line 401a (or cutting a plurality of notches <NUM> in the covering membranes <NUM> close to the second profile line 402a, wherein the sizes of the notches <NUM> can exactly ensure that the stent graft is straightened along the first profile line 401a ); after the first bent section 400a is straightened as shown in <FIG>, obtaining the length r and the diameter d1 of the straightened first bent section 400a; sleeving an inner tube with a diameter of d2 (d2 is less than d1, for example, d2 is equal to <NUM>%*d1) with the straightened first bent section 400a; applying pressure F (1N≤F≤2N) in the axial direction to the stent graft till the stent graft cannot shorten to obtain the total length s of the region B; and calculating the axial shortening rate of the stent graft in the region B according to the formula (r-s)/r*<NUM>%. The other method is as follows: also by taking the first bent section 400a as an example, re-arranging the wavy rings <NUM> in the axial direction according to the wave spacing between the wavy rings <NUM> at the first profile line 401a, covering the wavy rings <NUM> with membranes (covering materials and a selected process are kept consistent with those of the original stent), as shown in <FIG>, and then calculating the shortening rate according to the above-mentioned method for calculating the shortening rate.

During the bending of the stent graft, when any one of the region B or the region A reaches the available maximum shortening value, a rigid axial supporting structure is formed in the region, so that the stent graft cannot continue to be bent. Referring to <FIG>, during the bending of the stent graft, one wavy ring <NUM> of the stent graft moves in the direction of pressure together with portions of the covering membranes <NUM> fixed to the wavy ring <NUM>, the portions of the covering membranes <NUM> fixed to the wavy ring <NUM> move together with portions of the covering membranes <NUM> distributed at the periphery of the wavy ring <NUM>, immediately the portions of the covering membranes <NUM> distributed at the periphery of the wavy ring <NUM> pull another wavy ring <NUM> nearby to move towards one side close to the wavy ring <NUM> till the wavy ring <NUM> cannot keep moving, and at this time a rigid axial supporting structure is formed on the stent graft, so that the stent graft is prevented from continuing to shorten anymore.

When the axial shortening rate of the stent graft in the region B is less than <NUM>%, the shortening rate of the region B is too small, and no matter to which direction the stent graft is bent, the region B easily reaches the available maximum shortening value, and the region B cannot shorten anymore, thereby restricting the stent graft from continuing to be bent. When the axial shortening rate of the stent graft in the region B is greater than <NUM>%, the axial supporting effect of the stent graft is poor, and the stent graft may enter the tumor cavity when the distal end of the stent graft shortens towards the proximal end of the stent graft, thus threatening the life of a patient. When the shortening rate of the stent graft in the region B is <NUM>%-<NUM>%, the stent graft can be bent towards all directions to adapt to bent blood vessels, and sufficient axial supporting force can be provided for the stent graft to achieve the axial shortening prevention effect, thus maintaining the tube cavity shape of the stent graft. Referring to <FIG>, the stent graft may be continuously bent towards different directions to better adapt to a bent blood vessel. For example, the axial shortening rate of the stent graft in the region B is <NUM>%-<NUM>%.

Referring to <FIG>, the circumferential angle covered by the region B on an outer surface of the stent graft is ε° which is greater than or equal to <NUM>° and less than or equal to <NUM>°. When ε° is less than <NUM>°, the circumferential angle covered by the region B on the outer surface of stent graft is small, so that poor axial supporting effect of the entire stent graft may be caused, and the stent graft may easily swing and retract under the impact of a blood flow, finally causing the stent graft to retract into the tumor cavity, and endangering the life of the patient; and when ε° is greater than <NUM>°, the circumferential angle covered by the region B on the outer surface of the stent graft is large, which is not conducive to stent bending. When ε° is greater than or equal to <NUM>° and less than or equal to <NUM>°, sufficient axial support can be provided for the stent graft, and when the stent graft is applied to a more bent blood vessel, no folding occurs, thereby keeping the tube cavity smooth, and enabling the stent graft to adapt to a wider range of vascular morphology.

In this embodiment, the region B includes two keel regions in the circumferential direction, namely a first keel region 300a and a second keel region 300b, which are located between the greater curvature side region 100a and the lesser curvature side region 100b, respectively. Circumferential angles covered by the first keel region 300a and the second keel region 300b on the outer surface of the stent graft are <NUM>°-<NUM>°, such as about <NUM>°-<NUM>°, and the circumferential angles covered by the first keel region 300a and the second keel region 300b may be identical or different. It will be appreciated that the region B may also include three or more keel regions as desired, the keel regions may be arranged in a spaced manner or continuously, and the wave shapes, the number of waves, the wave heights, and the wave angles of the wavy segments of each keel region may be set as desired.

In the illustrated embodiment, the second wavy segment includes a second proximal vertex 102b, and the connecting line between the second proximal vertexes 102b of the adjacent second wavy segments is parallel to the axis of the stent graft.

Further, referring to <FIG>, at least one proximal wavy ring 101a is disposed at one end of the plurality of wavy rings <NUM>.

Where, the wave included angle of the proximal wavy ring 101a is <NUM>°-<NUM>°, the waves of the proximal wavy ring 101a and the wavy rings <NUM> are the same, and both are V-shaped, Z-shaped, M-shaped, or the like, and the number of the waves of the proximal wavy ring 101a in the circumferential direction is greater than the number of the waves of the wavy ring <NUM> in the circumferential direction. Due to the fact that the proximal wavy rings 101a located at an end portion of the stent graft has a greater number of waves in the circumferential direction, the radial supporting force of the end portion of the stent graft is high, and the wall adhering effect of the end portion of the stent graft may be effectively improved.

It will be appreciated that at least one distal wavy ring (not shown) is also disposed at the other end of the plurality of wavy rings <NUM>, the wave included angle of the distal wavy ring is <NUM>°-<NUM>°, the waves of the distal wavy ring and the wavy rings <NUM> are the same, and both are V-shaped, Z-shaped, M-shaped, or the like, and the number of the waves of the distal wavy ring in the circumferential direction is greater than the number of the waves of the wavy ring <NUM> in the circumferential direction. Where, both the proximal wavy ring and the distal wavy ring are made of materials having good biocompatibility, such as nickel titanium, stainless steel or the like. The proximal wavy ring and the distal wavy ring are both of closed cylindrical structures. The proximal wavy ring and the distal wavy ring may be of Z-shaped wave, M-shaped wave, V-shaped wave or sinusoidal wave structures, or of other structures that are radially compressible to a very small diameter. It will be appreciated that not only the numbers of the proximal wavy ring and the distal wavy ring may be set as desired, but also the wave shapes, the number of waves, and the wave heights of the proximal wavy ring and the distal wavy ring may be set as desired.

Further, the stent graft further includes an anchoring bare stent <NUM> located at one or two ends of the stent graft and connected with the proximal wavy ring or the distal wavy ring.

<FIG> shows a stent graft provided by a second exemplary embodiment of the present application, which differs from the first embodiment in that a connecting line between the second proximal vertexes 102b of the adjacent second wavy segments is disposed obliquely with respect to the axis of stent graft.

<FIG> shows a stent graft provided by a third exemplary embodiment of the present application, which differs from the first embodiment in that the second supporting bodies 104b that are connected to one sides of the second proximal vertexes 102b and close to the greater curvature side region 100a are distributed in the direction parallel to the axial direction of the stent graft, and the second supporting bodies 104b that are connected to the other sides of the second proximal vertexes 102b and close to the lesser curvature side region 100b are disposed obliquely with respect to the axis direction of the stent graft.

When the stent graft shown in <FIG> is bent in a direction indicated by a first arrow <NUM>, referring to <FIG>, the second supporting bodies 104b, adjacent to the greater curvature side region 100a, of the adjacent second wavy segments abut against mutually to form axial support, and the included angle between the second supporting bodies 104b, adjacent to the greater curvature side region 100a, of the adjacent second wavy segments is η°. When the stent graft of <FIG> is bent in a direction indicated by a second arrow <NUM>, referring to <FIG>, the second supporting bodies 104b, adjacent to the lesser curvature side region 100b, of the adjacent second wavy segments abut against mutually to form axial support, and the included angle between the second supporting bodies 104b, adjacent to the lesser curvature side region 100b, of the adjacent second wavy segments is θ°. As can be seen from the figures, η° is less than θ°. When the second supporting bodies 104b of the adjacent second wavy segments abut against mutually to form the axial support, the greater the included angle between the second supporting bodies 104b of the adjacent second wavy segments is, the smaller the force divided to the axial direction of the stent graft is, and the poorer the axial supporting effect on the stent graft is. Therefore, the axial supporting effect formed when the second supporting bodies 104b distributed in the direction parallel to the axial direction of the stent graft abut against mutually in <FIG> is superior to the axial supporting effect formed when the second supporting bodies 104b disposed obliquely with respect to the axis direction of the stent graft abut against mutually in <FIG>. Meanwhile, when the included angle between the second supporting bodies 104b of the adjacent second wavy segments is greater, excessive deformation of the covering membranes of the keel regions is easily caused to bring about an uneven surface of the stent graft, thus leading to high probability of thrombosis.

Claim 1:
A stent graft, comprising a plurality of wavy rings (<NUM>), wherein the stent graft further comprises, along a circumferential direction, a region A and a region B connected with the region A; each wavy ring (<NUM>) comprises first wavy segments located in the region A and second wavy segments located in the region B; region A being for fenestration; the ratio of a wave height (L1) of the first wavy segment to a spacing (L2) between the adjacent first wavy segments ranges from <NUM>/<NUM> to <NUM>; a wave included angle (α) of each second wavy segment ranges from <NUM>° to <NUM>°; the ratio of a wave height (L3) of the second wavy segment to a spacing (L4) between the adjacent second wavy segments ranges from <NUM>/<NUM> to <NUM>/<NUM>; and the ratio of the wave height (L1) of the first wavy segment to the wave height (L3) of the second wavy segment is greater than or equal to <NUM>/<NUM> and less than <NUM>; characterized in that a wave included angle (α) of each first wavy segment ranges from <NUM>° to <NUM>°.