Aortic stent graft capable of step-by-step release

Abstract

The present invention discloses a step-by-step release aortic stent graft, comprising a tubular graft and an annular support frame. Connectors for threading a release guidewire are axially arranged on the graft from the proximal end to the distal end, with the connectors arranged in at least two axially spaced rows. The present invention provides a step-by-step release aortic stent graft that enables precise positioning during the release process and offers high stability during assembly.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and specifically relates to a covered stent, and more particularly to an aortic covered stent that can be released in steps and can be used for interventional treatment of aortic diseases. Background Art

[0002] An aortic aneurysm is a localized or diffuse abnormal dilation of the aortic wall, which compresses surrounding organs and causes symptoms. Aortic aneurysms are primarily categorized by structure as true aortic aneurysms, false aortic aneurysms, and dissecting aortic aneurysms. Aortic aneurysms increase the pressure inside the vessel, leading to progressive enlargement. If prolonged, they can eventually rupture, with the larger the aneurysm, the greater the likelihood of rupture. Statistics show that without surgical treatment, 90% of thoracic aortic aneurysms and three-quarters of abdominal aortic aneurysms result in death within five years.

[0003] Thoracic endovascular aortic repair (TEVAR) is currently used to treat a variety of aortic dilatation lesions, including aortic dissection, penetrating aortic ulcers, intramural hematomas, thoracic aortic aneurysms, and pseudoaneurysms. Since the first case of abdominal aortic aneurysm treatment was reported in the 1990s, abdominal endovascular aortic repair (EVAR) has rapidly developed in just 20 years due to its advantages, including minimal invasiveness, short surgical and hospital stays, rapid postoperative recovery, and low perioperative mortality and complication rates.

[0004] TEVAR and EVAR often use expandable covered stents as treatment devices. In order to maintain good adhesion to the blood vessel to be repaired, the diameter of the covered stent after release is generally about 10% larger than the blood vessel diameter. Since the covered stent is tightly attached to the blood vessel after complete release, it cannot be readjusted even if the release position is inaccurate. This requires the surgical operator to have rich experience and spend a lot of time to accurately locate the release angle of the stent before stent release. Therefore, it is necessary to develop a stent that can still adjust its position after the stent is released in the blood vessel. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an aortic covered stent that can be accurately positioned during the release process and has high stability during assembly and can be released in steps, in response to the defects of the existing technology.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A step-by-step releasable aortic stent graft comprises a tubular graft and an annular support frame. Connectors for threading and releasing guide wires are axially arranged on the graft from the proximal end to the distal end, and the connectors are axially spaced in at least two rows.

[0008] Furthermore, in the aortic covered stent that can be released in steps, the connecting piece is preferably a closed-loop structure or an open-loop structure for the release guide wire to be passed through or wrapped around; the closed-loop structure is that the connecting piece has a through hole for the release guide wire to pass through, or the connecting piece and the covering cooperate to form a through hole or gap for the release guide wire to pass through; the open-loop structure is that the connecting piece has a limiting groove for the release guide wire to pass through.

[0009] Furthermore, in the step-by-step releasable aortic stent graft, the connector is preferably a soft connector that is disposed on the graft or can be attached to the graft.

[0010] Furthermore, in the aortic covered stent that can be released in steps, the connecting member is preferably a coil fixed on the outer wall of the covering; or the connecting member is a section of axially spaced fixed wire rope, and a gap is formed between the spaced fixed wire rope and the covering for the release guide wire to pass through; or the connecting member is a through hole provided on the covering; or the connecting member is at least two rows of soft connecting buckles with limiting grooves, and the limiting groove openings of different rows are arranged back to back.

[0011] Furthermore, in the step-by-step releasable aortic stent graft, preferably, at least one axially arranged support rod is fixed to the graft at least at the proximal end along the circumference of the graft.

[0012] Furthermore, in the aortic covered stent that can be released in steps, the support rod is preferably fixed on the outer wall or inner wall of the covering, the connecting piece is fixed on the position of the outer wall of the covering corresponding to the support rod, or the connecting piece is arranged on the support rod or on the covering near the support rod.

[0013] Furthermore, in the step-by-step releasable aortic stent graft, the support rod is preferably fixed to the graft by suturing, heat sealing or bonding.

[0014] Furthermore, in the step-by-step releasable aortic covered stent, it is preferred that at least one fixing point for fixed connection with the covering is provided on the support rod, and the fixing point is a connecting hole or an open groove with an opening provided on the support rod.

[0015] Furthermore, in the step-by-step releasable aortic covered stent, preferably, the support rods are arranged parallel to the central axis of the stent; or the support rods are arranged in an eight-shaped or inverted eight-shaped shape.

[0016] Furthermore, in the step-by-step releasable aortic covered stent, the stent is preferably a tubular structure with equal diameter extension or a tubular structure with non-equal diameter extension.

[0017] Furthermore, in the step-by-step releasable aortic stent graft, the stent is preferably a tubular structure extending in equal diameters, and a window for placing a branch stent or a branch blood vessel is provided at the proximal end or the middle portion of the stent;

[0018] Alternatively, the stent is a tubular structure with non-uniform diameter extension, including a main section and an extension section, the diameter of the main section is larger than the diameter of the extension section, and a transition section is provided between the main section and the extension section; the main section and / or the transition section are provided with a window for placing a branch stent or a branch blood vessel.

[0019] The present invention provides a coated stent, which is provided with several rows of connectors on the coating. The stent between two rows of connectors is folded, that is, two or more adjacent connectors are pulled closer together, and is then passed through the connectors on a release guide wire of a delivery device; after being bound and fixed, the stent can maintain a semi-expanded state in the blood vessel to be repaired. The diameter of the stent in the semi-expanded state is smaller than the diameter of the blood vessel, and the stent can freely rotate and move longitudinally in the blood vessel to adjust its position, which facilitates the precise positioning of the stent during the release process.

[0020] A support rod is provided inside or outside the covering. On the one hand, the support rod can facilitate the folding of the bracket. On the other hand, the support rod can be used as a tie column when assembling the bracket, which can not only ensure the stability of the bracket during the assembly process, but also ensure the stable semi-expanded state of the circumferential structure after the bracket is partially released. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 This is a schematic structural diagram of a stent graft according to embodiment 1 of the present invention;

[0023] Figure 2 1 is a schematic diagram of the rear structure of the stent graft in the lower half of the restraint release state according to embodiment 1 of the present invention;

[0024] Figure 3 This is a schematic structural diagram of a single-ring annular support frame according to embodiment 1 of the present invention;

[0025] Figure 4 Schematic diagram of only the proximal end of the stent graft being released during the release process of the stent graft according to Example 1 of the present invention;

[0026] Figure 5 This is a schematic diagram of the structure of the stent graft according to embodiment 2 of the present invention;

[0027] Figure 6 This is a schematic diagram of the support rod structure of Example 2 of the present invention;

[0028] Figure 7 2 is a schematic diagram of the rear structure of the stent graft in the second embodiment of the present invention when the stent graft is half released under restraint;

[0029] Figure 8 This is a schematic diagram of the structure of the stent graft according to Example 3 of the present invention;

[0030] Figure 9 This is a schematic structural diagram of a funnel-shaped annular support frame according to Example 3 of the present invention;

[0031] Figure 10 This is a schematic diagram of the structure of the stent graft according to Example 4 of the present invention;

[0032] Figure 11 This is a schematic diagram of the structure of the stent graft according to Example 5 of the present invention;

[0033] Figure 12 This is a schematic diagram of the structure of a window support frame according to embodiment 5 of the present invention;

[0034] Figure 13A The present invention is a schematic diagram of the back structure of Example 5 in which only the proximal end of the stent graft is released during the release process;

[0035] Figure 13B This is a front structural schematic diagram of a stent graft in which only the proximal end of the stent graft is released during the release process of the stent graft in Example 5 of the present invention; DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0037] The "proximal end" mentioned in the present invention refers to the part of the stent or stent component close to the patient's heart along the direction of blood flow, and the "distal end" refers to the part of the stent or stent component far away from the patient's heart.

[0038] Definition of front and rear: The tube surface of the bracket with the window is the front wall, the tube surface of the bracket opposite the window is the rear wall, and the tube surfaces on both sides of the bracket between the front wall and the rear wall are the side walls.

[0039] Example 1, as Figure 1 As shown, an aortic covered stent that can be released in steps includes a tubular covering 120 and an annular support frame 110. The covering 120 is axially provided with connectors 142 for threading and releasing guide wires from the proximal end to the distal end, and the connectors 142 are axially spaced in at least two rows.

[0040] The tubular covering 120 can be a straight tube with a constant diameter, or a funnel, dumbbell, or other suitable shape with a non-constant diameter structure. This embodiment uses a straight tube with a constant diameter structure. Covering 120 is made of a polymer material with good biocompatibility, preferably PET film in this embodiment, with a thickness of 0.07 mm to 0.1 mm. Covering 120 has good mechanical strength and anti-internal leakage performance.

[0041] The annular support frame 110 plays a supporting role for the membrane 120. A plurality of annular support frames 110 are uniformly sutured on the membrane 120 in parallel along the axial direction of the membrane 120. The annular support frames 110 at the proximal and / or distal ends of the stent are bare stents partially sutured on the membrane 120. Figure 1 As shown, a plurality of annular support frames 110 are sequentially arranged from the proximal end to the distal end of the membrane 120. The annular support frame 110 located at the proximal end of the membrane stent is a semi-sutured stent, and its extended section is sutured on the membrane 120. Figure 3 As shown, each ring support frame 110 is cylindrical and consists of multiple Z-shaped or sine waves. Each Z-shaped or sine wave has a crest 111 and an adjacent trough 112. There is a connecting rod 113 between the crest 111 and the adjacent trough 112. Each ring support frame 110 is woven with a super elastic nickel titanium wire. The nickel titanium wire diameter is relatively thin and can be between 0.2 and 0.5 mm. In this embodiment, a nickel titanium wire with a diameter of 0.45 mm is woven. The number of Z-shaped or sine waves is 6, and the vertical height of the ring support frame is 12 mm. Figure 3 Each ring-shaped support frame 110 is shown with a connecting steel sleeve 114. The two endpoints of the nickel-titanium wire are inside the connecting steel sleeve 114, and then the two endpoints of the nickel-titanium wire are fixed inside the steel sleeve by mechanical compression or welding. The ring-shaped support frame 110 is fixed to the inner or outer surface of the coating 120 by suturing, heat sealing, or bonding or other processes. The stent specification of this embodiment is 30 specifications, that is, the diameter of the ring-shaped support frame 110 and the coating 120 is 30 mm. The ring-shaped support frame 110 is fixed to the outer surface of the coating 120 by suturing, maintaining the good resilience of the coated stent as a whole.

[0042] The connecting member 142 is used to axially pass the release guide wire 141 and assist the release guide wire 141 in radially restraining the stent to form a semi-expanded state. Figure 2 As shown, a schematic diagram of the structure of the coated stent in Example 1 of the present invention is shown, in which a release guide wire is inserted at the connector to restrain the lower half of the stent. The structure of the connector 142 needs to meet the above purposes at the same time, so the connector 142 can choose two structures: a closed-loop structure or an open-loop structure for the release guide wire 141 to be inserted or wrapped. In the first structural formula, the closed-loop structure is that the connector 142 has a through hole for the release guide wire 141 to pass through, or the connector 142 cooperates with the coating 120 to form a through hole or gap for the release guide wire 141 to pass through. Specifically, the first embodiment is: the connector 142 is a coil fixed to the outer wall of the coating; the second embodiment is: the connector 142 is a section of axially spaced fixed wire rope, and a gap is formed between the fixed wire rope and the coating for the release guide wire 141 to pass through; the third embodiment is: the connector 142 is a through hole directly set on the coating.

[0043] The open-loop structure has a limiting groove for the release guide wire 141 to pass through, that is, the connecting member 142 is at least two rows of soft connecting buckles with limiting grooves, and the openings of different rows of limiting grooves are set back to back. The release guide wire 141 passes through the limiting grooves of different rows of soft connecting buckles in turn to restrain the bracket.

[0044] In order to prevent the connector from damaging the blood vessel during the stent release process, the connector 142 is a soft connector that is arranged on the membrane or can be attached and fixed on the membrane. The shape of the connector is not limited and can be any shape that meets the requirements of the present invention, preferably for example: a soft coil, a soft rope, etc. The connector is preferably made of a biocompatible polymer material, such as polyester, and a metal material, such as a metal wire, can also be selected.

[0045] In this embodiment, the connecting piece 142 is a coil with a through hole, and the through hole can pass the release guide wire 141 with a wire diameter of 0.5mm to 1.5mm. In this embodiment, the release guide wire 141 is preferably made of nickel-titanium alloy wire with a wire diameter of 0.5mm. The number of connecting pieces 142 is 6, which are evenly fixed on the coating 120 in two rows, with three connecting pieces 142 in each row, and the three connecting pieces 142 are axially spaced. Figure 2 As shown, during assembly, first pull the two rows of connectors 142 together, and then the fixed release guide wire 141 of the delivery device sequentially passes through the connectors 142 of different rows to form a constraint on the stent. The stent graft is kept in a semi-expanded state under the constraint of the release guide wire 141, and then the stent is completely pressed and gripped in the delivery sheath. Figure 4 As shown, when releasing, the part of the proximal end of the coated stent that is not restrained by the release guide wire 141 is released first. At this time, the coating 120 between the connectors 142 is still in a restrained state, the distal coating is contracted in the outer sheath 20, and the proximal annular support frame 110 as a bare stent is still restrained in the conveyor TIP head 10. The coated stent is not completely released, and the overall diameter is smaller than the blood vessel diameter. It can rotate freely and move longitudinally in the blood vessel, which facilitates the precise positioning of the stent. After finding the correct release position of the stent, the release guide wire 141 is withdrawn, and the coated stent is completely released and firmly adheres to the blood vessel.

[0046] Example 2, as Figure 5 As shown, this embodiment is an improvement based on embodiment 1.

[0047] A step-by-step release aortic stent graft includes a tubular graft 120 and an annular support frame 110 fixed to the graft 120. The graft 120 is circumferentially fixed with at least one axially arranged support rod 130 at least at the proximal end thereof. The support rod 130 is fixed to the outer wall or inner cavity wall of the graft 120. A connector 142 is fixed to a position on the outer wall of the graft 120 corresponding to the support rod 130, or the connector 142 is disposed on the graft 120 near the support rod 130. In this embodiment, the support rod 130 is disposed on the inner wall of the graft 120, and a connector 142 for securing a release guidewire is provided on the outer side of the graft 120 corresponding to the support rod 130.

[0048] The first function of the support rod 130, that is, the most important function is to form a stent in a semi-expanded state, that is, to pull two or more adjacent support rods 130 closer together and fix them through the connecting piece 142. During the pulling process, the support rod 130 can always maintain the flatness of the coating and the stability of the overall structure of the stent. The coating 120 and the annular support frame 110 between the support rods 130 are folded, reducing the diameter of the stent to form a semi-expanded state. The diameter of the stent in the semi-expanded state is smaller than the diameter of the blood vessel, and can freely rotate and move longitudinally in the blood vessel to adjust its position, which is convenient for the precise positioning of the stent during the release process.

[0049] The support rods 130 are arranged axially along the circumference of the coating 120. The multiple support rods 130 are preferably arranged axially symmetrically. There are two types of relative positions between the support rods 130: one is that the support rods 130 are arranged parallel to the central axis of the stent; the other is that they are not parallel to the central axis of the stent, that is, the support rods 130 are arranged in an "eight" or "inverted eight" shape. Figure 7 As shown, when support rods 130 are arranged parallel to the central axis of the stent, the diameter of the stent is synchronously reduced after being constrained and fixed. For example, if the stent is originally a straight cylindrical stent, it will also be a straight cylindrical stent in the semi-expanded state. When support rods 130 are arranged non-parallel to the central axis of the stent, the diameter of the stent is asynchronously reduced after being constrained and fixed. For example, if the stent is originally a straight cylindrical stent, it will be conical in the semi-expanded state. In this embodiment, it is preferred that support rods 130 be arranged parallel to the central axis of the stent. The number of support rods 130 provided is generally 2-6, and preferably 2-3.

[0050] The support rod 130 is at least arranged at the proximal end of the coating 120, which means that the proximal end of the support rod 130 is arranged at the proximal end of the coating 120. The support rod 130 can extend toward the distal end of the stent. Its extension length can extend to the axial middle of the stent or to the axial distal end of the stent as needed.

[0051] like Figure 5As shown, in this embodiment, two support rods 130 are preferably fixed to the inner surface of the tubular structure coating 120. The two support rods 130 are located at the rear of the proximal end of the coating 120 and are fixed to the inner wall of the coating 120 by suturing, heat sealing or bonding, preferably by suturing.

[0052] The support rod 130 is made of metal or polymer material with a certain support strength, preferably metal material, such as nickel titanium alloy wire, with a wire diameter ranging from 0.3mm to 0.6mm. In this embodiment, the wire diameter is preferably 0.45mm. The structure of the support rod 130 is as follows Figure 6 As shown, the support rod 130 shown in the figure is a straight rod structure, and at least one fixed point is provided on the support rod 130. The support rod 130 is fixed to the inner wall of the coating 120 by suturing, heat sealing or bonding through the fixed point. The fixed point is a connecting hole or an open groove with an opening provided on the support rod 130. In this embodiment, there are two fixed points at both ends of the support rod 130. The fixed points of this embodiment are two limiting round heads 131 with connecting holes, which are formed by curling the two ends of the support rod 130. The diameter range of the limiting round head 131 is 1.5mm to 3.5mm. In this embodiment, the limiting round head 131 preferably has a diameter of 2.5mm. The limiting round head 131 is fixed to the proximal end of the coating 120 by suturing to prevent the support rod 130 from slipping axially in the bracket. In addition to the connecting hole, the fixing point can also be a non-closed loop structure, or an open slot with an opening. For example, the support rod 130 is bent at a certain point to form a semicircular or arc-shaped open slot. After being fixed at the open slot, the support rod 130 cannot move axially.

[0053] like Figure 7 As shown, in this embodiment, the support rod 130 not only plays a supporting role in the axial direction, but also serves as a bolt during the assembly of the coated stent, which can not only ensure the stability of the stent during the assembly process, but also ensure the semi-expanded state of the circumferential structure stability after the stent is partially released. The diameter of the stent in the semi-expanded state is smaller than the diameter of the blood vessel, and it can freely rotate and move longitudinally in the blood vessel to adjust its position, which facilitates the precise positioning of the stent during the release process.

[0054] The remaining structures are the same as those in Example 1 and will not be described again here.

[0055] Example 3: This example is an improvement on Example 2. The difference between the two is that the coating 120 of this example is a tubular structure with non-uniform diameter extension.

[0056] like Figure 8As shown, Example 2 of the present invention comprises a multi-ring annular support frame 110. It includes a funnel-shaped covering 120, annular support frames 110 and 140 fixed to the covering 120, and two support rods 130 fixed to the inner wall of the covering 120. The configuration of the support rods 130 in Example 2 is the same as that of the support rods 130 in Example 1 and will not be repeated here.

[0057] The stent graft has a funnel-shaped structure, comprising a main section 100A and an extension section 100C. A transition section 100B is located between the main and extension sections 100A and 100C, with the diameter of the extension section 100C being smaller than that of the main section 100A. Both the main and extension sections 100A and 100C comprise a straight cylindrical graft 120 and an annular support frame 110, respectively. The transition section 100B comprises a funnel-shaped graft 190 and a funnel-shaped annular support frame 140.

[0058] like Figure 9 As shown, the funnel-shaped annular support frame 140 is composed of multiple Z-shaped or sinusoidal waves, each of which has a crest 111 and an adjacent trough 112. A connecting rod 113 is provided between crest 111 and adjacent trough 112. Annular support frame 140 differs from annular support frame 110 in the embodiment in that it is tapered, with the diameter difference between the two ends of annular support frame 140 being 10 mm.

[0059] The remaining structures are the same as those in Example 2 and will not be described again here.

[0060] Example 4: This example is an improvement on Example 2.

[0061] The difference between the two is that the stent graft of this embodiment is further provided with a long branch segment 102A and a short branch segment 102B at the distal end of the stent graft of embodiment 2. Figure 10 As shown, the stent graft of Example 2 is the main stent 101 of this Example 4. The configuration of the main stent 101 is the same as that of Example 2. Two support rods 130 are fixedly provided on the inner wall of the coating 120. Connectors 142 for fixing the release guide wire are provided on the outer side of the coating 120 corresponding to the support rods 130. The configuration of the support rods 130 and connectors 142 of Example 4 is the same as that of Example 2 and will not be repeated here.

[0062] The distal end of the main support 101 is connected to two branch segments, namely a long branch segment 102A and a short branch segment 102B.

[0063] The long branch segment 102A and the short branch segment 102B are circumferentially provided with a branch segment coating 120A and a branch segment coating 120B, respectively. The branch segment coating 120A and the branch segment coating 120B are sewn together with the coating 120 of the main support 101 to form an integral structure, or are an integral structure formed integrally with the coating 120. The branch coating 120A is a straight cylindrical structure with a diameter ranging from 10mm to 14mm and a length of 70mm; the branch coating 120B is also a straight cylindrical structure with a diameter ranging from 10mm to 14mm and a length of 30mm. A transition zone can also be provided between the coating 120 and the branch segment coating 120A and the branch segment coating 120B to connect the main support and the long branch segment 102A and the short branch segment 102B. The length of the transition zone ranges from 10mm to 20mm, preferably 15mm. The materials of the coating 120, the branch segment coating 120A and the branch segment coating 120B can be selected from polyester, polyurethane, ePTFE, PET or other polymer materials. In this embodiment, the material selected is PET film, and the thickness of the PET film ranges from 0.07mm to 0.12mm, preferably 0.1mm.

[0064] The outer wall or inner wall of the branch segment coating 120A and the branch segment coating 120B are respectively fixed by sutures of a plurality of branch annular stents 121A and branch annular stents 121B arranged in intervals and sequence. The stent material of the branch annular stents 121A and the branch annular stents 121B is preferably nickel-titanium alloy wire with good biocompatibility and superelasticity.

[0065] The remaining structures are the same as those in Example 2 and will not be described again here.

[0066] Example 5: This example is an improvement on Example 2 or 3. The difference is that a window 300 for arranging branch blood vessels is provided on the covering film 120.

[0067] There are two structures of the coating 120, and there are two situations for opening the window 300. One is as follows Figure 11 The coating 120 shown is a tubular structure extending in equal diameters, and a window 300 for setting a branch blood vessel is provided at the proximal end or the middle portion of the coating 120; the window 300 is located on the coating 120 between two adjacent support rods, and the window support frame 180 surrounding the window 300 is set away from the window 300. Two or more windows 300 are simultaneously set in the same area between the two support rods 130, preferably on the front wall of the stent, and the center lines of the two windows are located on the same axis. Another embodiment is that the coating 120 is a tubular structure extending in non-equal diameters, including a main body section and an extension section, the diameter of the main body section is larger than the diameter of the extension section, and a transition section is provided between the main body section and the extension section; the main body section or the transition section is provided with a window 300 for setting a branch blood vessel.

[0068] The present invention is an improvement on the basis of embodiment 2. The annular support frame includes an annular support frame 110 as a main body, a window support frame 180 corresponding to the window 300, and a window support frame 180. Figure 11 As shown, in the window support frame 180, a window corrugated unit is provided corresponding to the window 300. That is, the annular support frame 110 of this embodiment includes an annular support frame 110 with a multi-ring structure and uniform diameter in the membrane stent, and the window support frame 180 is provided with a single-ring metal ring 160 at the window 300, and two support rods 130 are fixedly provided on the inner surface of the membrane 120. Figure 12 As shown, the window support frame 180 is composed of multiple Z-shaped or sinusoidal waves and a window waveform unit. Each Z-shaped or sinusoidal wave has a peak 111 and an adjacent trough 112, with a connecting rod 113 between the peak 111 and the adjacent trough 112. The window waveform unit has two peaks 121 and a trough 122, and the window waveform unit is located between the two peaks 111 of the Z-shaped or sinusoidal wave. The peak 121 and the trough 122 of the window waveform unit have two connecting rods 123, and the peak 121 and the two peaks 111 of the Z-shaped or sinusoidal wave have two connecting rods 124. The window support frame 180 is woven from a superelastic nickel-titanium wire with a wire diameter ranging from 0.2 to 0.5 mm, and preferably 0.45 mm in this embodiment. The number of Z-shaped or sinusoidal waves is 6, and the vertical height of the window support frame 180 is 15 mm. There is a connecting steel sleeve 314 on the window support frame 180, and the two end points of the nickel-titanium wire are inside the connecting steel sleeve 114, and then the two end points of the nickel-titanium wire are fixed inside the steel sleeve by mechanical compression or welding.

[0069] like Figure 13A As shown, the stent graft is held in a semi-released state by a fixed release guidewire 141 on the conveyor. The release guidewire 141 sequentially passes through connectors 142. In this embodiment, the release guidewire 141 is preferably made of nickel-titanium alloy wire with a diameter of 0.5 mm. The connectors 142 are six in number and are fixed to the support rod 130 in two rows, with three connectors 142 in each row. The three connectors 142 are located at both ends and in the middle of the support rod 130.

[0070] like Figures 13A-13BAs shown, when the stent graft is released, it is in a semi-released state under the restraint of the guidewire 141. The portion of the stent behind the window 300 at the proximal end of the stent graft is still in a restrained state, the overall diameter of the stent is small, and the annular window 300 at the front is in an expanded state. In clinical application, this state is not fully expanded, the distal stent graft is contracted in the outer sheath 20, and the proximal bare stent 110 is still restrained in the conveyor TIP head 10. The overall diameter is small, and the stent graft can be conveniently rotated axially and circumferentially within the blood vessel through the conveying system, which can more quickly and accurately locate the exact position of the annular window 300, thereby smoothly anastomosing the branch blood vessel, shortening the operation time and improving the success rate of the operation. On the other hand, the support rod 130 can also serve as a bolt when assembling the stent graft, which can not only ensure the stability of the stent during the assembly process, but also ensure the semi-expanded state of the circumferential structure of the stent after partial release, preventing the window 300 from deforming when the stent is in a semi-assembled or semi-released state, which may lead to inaccurate positioning.

[0071] The remaining structures are the same as those in Example 2 or 3 and will not be described again here.

Claims

1. A step-by-step releasable aortic stent graft comprising a tubular graft and an annular support frame, characterized in that: The annular support frame is fixed to the outer surface of the membrane, and a connector for threading and releasing a guide wire is axially arranged on the membrane from the proximal end to the distal end, and the connectors are axially spaced apart and arranged in at least two rows; at least two axially arranged support rods are fixed on the membrane at least at the proximal end along the circumference of the membrane; the support rods are fixed on the inner cavity wall of the membrane, and the connectors are fixed on the outer side wall of the membrane at positions corresponding to the support rods; a window for arranging a branch blood vessel is provided at the proximal end or the middle part of the membrane, and the window is located on the membrane between two adjacent support rods, and a plurality of the windows are simultaneously arranged in the same area between the two support rods; The support rod is a straight rod structure; at least two of the support rods are axially symmetrically arranged; The stent is formed into a semi-expanded state by the support rods, wherein adjacent support rods are drawn close together and fixed by the connecting piece, and the coating and the annular support frame between the support rods are folded to form the stent in the semi-expanded state; the diameter of the stent in the semi-expanded state is smaller than the diameter of the blood vessel.

2. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The connecting piece is a closed-loop structure or an open-loop structure for the release guide wire to pass through; the closed-loop structure is that the connecting piece has a through hole for the release guide wire to pass through, or the connecting piece and the coating cooperate to form a gap for the release guide wire to pass through; the open-loop structure is that the connecting piece has a limiting groove for the release guide wire to pass through.

3. The step-by-step releasable aortic stent graft according to claim 2, characterized in that: The connecting piece is a soft connecting piece arranged on the covering film.

4. The step-by-step releasable aortic stent graft according to claim 2, characterized in that: The connecting piece is a soft connecting piece that can be attached and fixed on the covering film.

5. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The connecting member is a coil fixed on the outer wall of the coating; or the connecting member is a section of axially spaced fixed rope, and a gap is formed between the spaced fixed rope and the coating for the release guide wire to pass through; or the connecting member is at least two rows of soft connecting buckles with limiting grooves, and the openings of the limiting grooves in different rows are arranged back to back.

6. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rod is fixed on the covering film by sewing or bonding.

7. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rod is fixed on the covering film by heat sealing.

8. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rod is provided with at least one fixing point for fixed connection with the covering film, and the fixing point is a connection hole provided on the support rod.

9. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rod is provided with at least one fixing point for fixed connection with the covering film, and the fixing point is an open groove with an opening on the support rod.

10. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rods are arranged parallel to the central axis of the bracket; or the support rods are arranged in an "eight" shape.

11. The step-by-step releasable aortic stent graft according to claim 1, characterized in that: The support rods are arranged in an inverted eight shape.

12. The step-by-step releasable aortic stent graft according to any one of claims 1 to 5, characterized in that: The stent is a tubular structure with equal diameter extension or a tubular structure with non-equal diameter extension.

13. The step-by-step releasable aortic stent graft according to claim 12, characterized in that: The stent is a tubular structure extending in equal diameters, and a window for placing a branch stent or a branch blood vessel is provided at the proximal end or the middle portion of the stent.

14. The step-by-step releasable aortic stent graft according to claim 12, characterized in that: The stent is a tubular structure with non-uniform diameter extension, including a main section and an extension section. The diameter of the main section is larger than the diameter of the extension section, and a transition section is provided between the main section and the extension section; the main section and / or the transition section are provided with a window for placing a branch stent or a branch blood vessel.

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