Covered stents and combined stents

Abstract

This invention relates to a covered stent and a combined stent. The covered stent includes a stent body, the stent body including a first stent segment and a second stent segment connected to the proximal end of the first stent segment. The first stent segment includes a covering. The second stent segment includes at least one first wave rod, and at least one segment of the distal end of the first wave rod is at a distance greater than the distance from the proximal end of the first wave rod to the axis of the covered stent. The combined stent includes a covered stent. By adjusting the structure of the bare stent, the covered stent avoids excessive stress concentration and impact on the vascular wall after release and implantation, thereby improving the covered stent's adaptability to the blood vessel and reducing the original irritation to the blood vessel.

Description

Technical Field

[0001] This invention relates to the field of interventional medical device technology, and in particular to a covered stent and a combined stent. Background Technology

[0002] With the rapid increase in the incidence of hypertension, the incidence of arterial-related diseases is also rising significantly, and is projected to increase by more than 40% in the next 5 to 7 years. Acute Stanford aortic dissection type A (AADA) is the most common and dangerous aortic emergency in cardiovascular surgery. Without treatment, the mortality rate of AADA within one week is as high as 50-91%. With only conservative medical treatment, the 24-hour mortality rate reaches 20%, and the 48-hour mortality rate can reach 30%. Therefore, AADA, once diagnosed, requires emergency surgical intervention if there are no contraindications. However, even under modern medical conditions, the perioperative mortality rate is as high as 15-35%.

[0003] Currently, minimally invasive endovascular interventional surgery can be used to treat the above-mentioned diseases. Specifically, a covered stent is implanted into the blood vessel to isolate blood flow from the aortic dissection. When using a covered stent, it is usually necessary to first compress and load the unstressed, naturally positioned stent into a sheath for subsequent transport and release to the designated site. After implantation, to ensure a tight fit between the covered stent and the vessel wall, the diameter of the covered stent is generally smaller than the vessel diameter. This means the covered stent is continuously subjected to pressure from the vessel wall. Since blood vessels (especially arteries) are subject to movement, the vessel wall continuously and dynamically compresses the covered stent. Because the bare stent portion of the covered stent lacks a covering structure, it is easily irritated by vessel movement, and the pressure at the tip may even become too concentrated, causing it to puncture the vessel wall. The bare stent portion plays a crucial role in anchoring and radial support. Therefore, a covered stent is needed that can preserve the structure of the bare stent while avoiding or reducing its irritation to the vessel wall. Summary of the Invention

[0004] Based on this, the present invention provides a covered stent and a combined stent to solve the problem that the covered stent is prone to irritating the blood vessel wall with blood vessel movement, and even the pressure of the end on the blood vessel wall is too concentrated and punctures the blood vessel wall.

[0005] A covered stent includes a stent body, the stent body including a first stent segment and a second stent segment connected to the proximal end of the first stent segment, the first stent segment including a covering, the second stent segment including at least one first wave rod, and at least one segment of the distal end of the first wave rod being at a distance from the axis of the covered stent to a distance greater than the distance from the proximal end of the first wave rod to the axis of the covered stent.

[0006] In one embodiment, the first wave rod includes at least a first segment near the proximal end and a second segment near the distal end, with the first segment and the second segment extending in opposite directions along the axial direction.

[0007] In one embodiment, the first segment is located inside the first support segment, and the second segment is located outside the first support segment.

[0008] In one embodiment, the rate of change of the distance from the first wave rod to the axis changes from a positive value to a negative value in the direction from the far end to the near end, and the absolute value of the rate of change first increases and then decreases.

[0009] In one embodiment, the second support segment has several curved surfaces, and the projections of a single waveform rod on the second support segment coincide on the curved surfaces.

[0010] In one embodiment, the relative distance between the projection of the single wave rod on the curved surface and the projection of the axis on the curved surface increases and then decreases, or increases and then remains unchanged, from the crest to the trough.

[0011] In one embodiment, the second support segment includes a first band and a second band, the first band and the second band are arranged opposite to each other, and the axial length of the first band is greater than the axial length of the second band.

[0012] In one embodiment, the second support segment includes a second wave rod, which extends in the same direction as the first wave rod but deflects at different degrees; or extends in a different direction than the first wave rod but deflects at the same degree; or extends in a different direction than the first wave rod and deflects at different degrees.

[0013] In one embodiment, the second support segment includes a third wave rod and a fourth wave rod, which are interlaced to form a mesh structure. The third wave rod and the fourth wave rod each include a first protrusion and a second protrusion, and the intersection of the third wave rod and the fourth wave rod is located at the maximum protrusion position of both the first protrusion and the second protrusion.

[0014] A composite stent includes a covered stent and a smaller stent, the smaller stent pressing against and abutting the proximal end of the first stent segment from the outside in, the proximal end of the covered stent of the smaller stent being flush with the proximal end of the covered stent of the first stent segment, and at least one segment from the proximal end of the second stent segment to the distal end of the second stent segment near the smaller stent having a tangential direction parallel to the axis.

[0015] The covered stent and combined stent provided by this invention, by adjusting the structure of the bare stent (i.e., the second stent segment), prevent excessive stress concentration and impact on the vascular wall after the covered stent is released and implanted, thereby improving the adaptability of the covered stent to the blood vessel and reducing the original stimulation of the blood vessel by the position of the bare stent. The combined stent also ensures that when used with other stents, the compression and deformation of the bare stent portion of the original covered stent will not stimulate the blood vessel wall, reducing and avoiding point contact between the bare stent and the blood vessel wall, thereby reducing the risk of stress concentration that could damage or even puncture the blood vessel wall. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the film-coated stent in the first embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the bare stent segment of the covered stent in the first embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the state during the release phase of the covered stent in the first embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram illustrating the release phase of a straight bare stent covered with a stent in the prior art.

[0020] Figure 5 This is a schematic diagram of the state after implantation of a bare stent covered with a stent in the existing technology;

[0021] Figure 6 This is a schematic diagram of the state of the covered stent after implantation in the first embodiment of the present invention;

[0022] Figure 7 This is a schematic diagram of the structure of the bare stent segment of the covered stent in one embodiment of the present invention;

[0023] Figure 8 yes Figure 7 A schematic diagram of the cross-section of the projection plane D;

[0024] Figure 9 This is a schematic diagram of the structure of the film-coated stent in the second embodiment of the present invention;

[0025] Figure 10 This is a schematic diagram of the working state of the covered stent in the third embodiment of the present invention;

[0026] Figure 11 This is a schematic diagram of the operation of a straight bare stent, a covered stent, and a small stent in the existing technology;

[0027] Figure 12 This is a schematic diagram of the working of the film-coated stent and the small stent in the fourth embodiment of the present invention;

[0028] Figure 13 This is a schematic diagram of the structure of the film-coated stent in the fifth embodiment of the present invention;

[0029] Figure 14 This is a schematic diagram of the bare stent segment of the covered stent in the fifth embodiment of the present invention;

[0030] Figure 15 This is a schematic diagram of the initial state of the release phase of the covered stent in the fifth embodiment of the present invention;

[0031] Figure 16 This is a schematic diagram showing the end state of the release phase of the covered stent in the fifth embodiment of the present invention;

[0032] Figure 17 This is a schematic diagram of the structure of the film-coated stent in the sixth embodiment of the present invention;

[0033] Figure 18 This is a first-view structural schematic diagram of the bare stent segment of the covered stent in the third embodiment of the present invention;

[0034] Figure 19 This is a second-view structural schematic diagram of the bare stent segment of the covered stent in the third embodiment of the present invention. Detailed Implementation

[0035] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0036] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] In the field of interventional medical devices, the proximal end of an implant (such as a stent) after deployment is typically defined as the end closer to the heart and the distal end as the end farther from the heart. "Axial" generally refers to the length direction of the implant during delivery, while "radial" generally refers to the direction perpendicular to the implant's "axial" direction. Based on this principle, the "axial" and "radial" of any component of the implant are defined.

[0039] First Embodiment

[0040] The coated scaffold 100 includes a bare scaffold 10 and a coating 20. The bare scaffold 10 is made of a biocompatible material, such as nickel-titanium or stainless steel. Generally, the bare scaffold 10 includes multiple spaced-apart metal coils. The coating 20 is made of a biocompatible polymer material, such as PTFE, FEP, or PET.

[0041] like Figure 1-2 As shown, Figure 1 This is a schematic diagram of the structure of the film-coated stent 10 in this embodiment. Figure 2 This is a schematic diagram of the bare stent segment 112 of the covered stent 10 in this embodiment. The covered stent 10 includes a stent body 11 and a covering 12 covering the surface of the stent body 11. The stent body 11 includes several wave-shaped rings arranged axially along the center line of the stent. It is generally made of materials with good biocompatibility, such as nickel-titanium or stainless steel. The covering 12 is made of polymer materials with good biocompatibility, such as PTFE, FEP, or PET.

[0042] The stent body 11 includes a covered stent segment 111 (first stent segment) and a bare stent segment 112 (second stent segment) connected to the proximal end of the covered stent segment 111. The bare stent segment 112 includes a wave-shaped ring. It is understood that the bare stent segment 112 may also include multiple wave-shaped rings. In another embodiment, the stent body includes a spiral ring. In this embodiment, the covering 12 located on the inner and outer surfaces of the stent body 11 is fixed by thermal fusion bonding. In addition to thermal fusion bonding, other connection methods such as adhesive bonding or sutures can achieve the same effect. This embodiment is not limited to any particular method. Each wave-shaped ring can be connected to each other or only connected through the covering 12. This embodiment is not limited to any particular method.

[0043] In this embodiment, the bare stent segment 112 includes at least one first wave rod 1121. The distance from at least a segment of the distal end of the first wave rod 1121 to the axis of the stent body 11 is greater than the distance from at least a segment of its proximal end to the axis of the stent body 11. That is, at least a segment of the distal end of the first wave rod 1121 is offset outward relative to at least a segment of its proximal end. Therefore, the near-peak segment of the first wave rod 1121 is closer to the axis of the stent body 11 than its near-trough segment.

[0044] Specifically, the first wave rod 1121 includes at least a first segment 11211 near the wave crest and a second segment 11212 near the wave trough. Viewed from the distal end to the proximal end, the first segment 11211 extends inward, and the second segment 11212 extends outward. Viewed from the proximal end to the distal end, the first segment 11211 extends outward, and the second segment 11212 extends inward. Therefore, along the axial direction, the extension directions of the first segment 11211 and the second segment 11212 are opposite. That is, viewed from the distal end to the proximal end (i.e., from the support body 11 to the bare support segment 112), the first wave rod 1121 first extends outward and then inward. Thus, the rate of change of the distance of the first wave rod 1121 from the axis changes from a positive value to a negative value (positive values ​​increase, negative values ​​decrease) from the distal end to the proximal end. Furthermore, the first segment 11211 is located inside the covered stent segment 111 of the covered stent 10, and the second segment 11212 is located outside the covered stent segment 111 of the covered stent 10.

[0045] In another embodiment, the absolute value of the rate of change of the distance from the first wave rod to the axis first increases and then decreases from the distal end to the proximal end, thereby making the extension of the proximal and distal ends of the first wave rod smoother and more easily conforming to the extension direction of the blood vessel wall.

[0046] The covered stent 10 includes a natural state and a compressed state. During the implantation surgery, the covered stent 10 is compressed to the compressed state and then loaded into the delivery sheath. The bare stent segment 112 of the covered stent 10 is bound to the tip at the distal end of the sheath core tube. The covered stent 10 is delivered along the sheath to the implantation site in the body. Then, the outer tube of the delivery sheath is gradually withdrawn. The bare stent segment 112 of the covered stent 10 is bound to the tip at the distal end of the sheath core tube, and the remaining part expands naturally. After confirming that the position of the covered stent 10 is accurate, the bare stent segment 112 of the covered stent 10 at the tip position is released, thereby releasing the covered stent 10.

[0047] According to the above process, during the release of the covered stent 10, there is a stage where the bare stent segment 112 is bound to the TIP head, and the covered stent segment 111 naturally expands. During this stage, the bare stent segment 112 is in a semi-open state, as shown in the reference. Figure 3-4 , Figure 3 This is a schematic diagram of the state of the covered stent 10 during the release phase in this embodiment. Figure 4This is a schematic diagram of the deployment phase of a bare stent covered with a stent. It is clearly visible that, due to the concave curved structure of the first wave rod 1121, the area of ​​the opening region 1123 formed by the first wave rod 1121 and adjacent wave rods is larger than the opening region 1124 of the straight-tube covered stent. In this embodiment, the bare stent segment 112 can provide a larger patency area, preventing blood flow obstruction. Furthermore, due to fluid characteristics, the blood flow velocity near the vessel centerline is slightly faster than that near the vessel wall. Since the rate of change of the distance from the first wave rod 1121 to the axis changes from positive to negative from the distal to the proximal end in this embodiment, the distal end of the bare stent segment 112, where the first wave rod 1121 is located, is closer to the vessel wall. This results in a larger opening region 1123 at the vessel wall, providing more space for the slower-moving blood flow at the vessel wall, ensuring unobstructed blood flow.

[0048] After the covered stent 10 is implanted, it remains in the blood vessel. To ensure that the covered stent 10 fully expands and adheres tightly to the inner wall of the blood vessel, the diameter of the covered stent 10 in its natural state is slightly larger than the inner diameter of the blood vessel at the implantation site. That is, the inner wall of the blood vessel will exert pressure on the covered stent 10. Figure 5 , Figure 5 This is a schematic diagram of the state after implantation of a straight bare stent covered with a stent 90. During implantation, the straight bare stent covered with a stent 90 is under pressure. The covered stent segment 911 has a larger contact area with the vessel wall, causing the shape of the straight bare stent covered with a stent 90 to be more inclined to maintain the shape of the covered stent segment 911 adhering to the vessel wall. Since the surface of the bare stent segment 912 is not covered, there is no structure to evenly distribute the pressure of the vessel wall. This causes the connection point between the covered stent segment 911 and the bare stent segment 912 to deform to adapt to the expansion state after implantation of the straight bare stent covered with a stent 90. That is, the connection point between the covered stent segment 911 and the bare stent segment 912 will slightly inward to compensate for the deformation. This results in the bare stent segment 912 taking on an outwardly flared trumpet shape, with its proximal end abutting against the vessel wall. At this time, the contact area between the proximal end of the bare stent segment 912 and the vessel wall is small, resulting in excessive pressure on the vessel wall and a high risk of damage. In addition, when the bare stent segment 912 is deployed, its proximal end has the greatest deformation relative to other locations, the longest stroke to recover its expanded state, and the greatest release force. At this time, when the proximal end of the bare stent segment 912 collides with the vessel wall (point contact), it is easy to cause excessive impact on the vessel wall.

[0049] Reference Figure 6 , Figure 6This is a schematic diagram of the state after implantation of the covered stent 10 in this embodiment. After implantation of the covered stent 10 in this embodiment, because the bare stent segment 112 in its natural state protrudes outward at the distal end near the covered stent segment 111, that is, the distal end of the bare stent segment 112 protrudes outward relative to the covered stent segment 111, the vessel wall will always be in contact with and press against the distal end of the bare stent segment 112. In other words, the distal end of the bare stent 112 has already undergone deformation compensation. On this basis, the bare stent segment 212 actually forms a near-straight cylinder. Furthermore, because the bare stent segment 112 in its natural state is concave inward at the proximal end far from the covered stent segment 111, the proximal end of the bare stent segment 212 will not contact the vessel wall. Moreover, when the bare stent segment 212 is released, as its proximal end expands toward the vessel wall, the distal protruding segment of the bare stent segment 112 first contacts the vessel wall, and then the concave segment of the proximal end of the bare stent segment 112 gradually contacts the vessel wall, thus avoiding point contact between the proximal end of the bare stent segment 112 and the vessel wall, thereby avoiding impact on the vessel wall.

[0050] In another embodiment, the bare support segment 112 includes a plurality of first wave rods 1121, which are spaced apart.

[0051] In another embodiment, the bare support segment 112 includes a plurality of first wave rods 1121, which are continuously distributed.

[0052] In another embodiment, the bare support segment 112 is entirely composed of the first wave rod 1121.

[0053] In this embodiment, since the distal end of the bare stent segment 112 has a protruding structure, it abuts against the blood vessel wall after release, eliminating the need for an anchoring structure and thus reducing damage to the blood vessel wall.

[0054] In another embodiment, the bare wave loop in the bare stent segment 112 may be partially covered by the covering 13, but the covered length is less than or equal to 75% of the total length L of the bare stent segment 112. This is to ensure that the proximal position of the covering 13 has sufficient support to avoid deformation or wrinkling due to blood impact.

[0055] In another embodiment, such as Figure 7 , Figure 7 This is a structural schematic diagram of the bare support segment 112. The bare support segment 112 has several curved surfaces D, such that the projections of a single-waveform wave rod 1122 on these curved surfaces D overlap and merge onto the projection surface to form a projected waveform 1123. A single waveform refers to a wave crest and the wave rod connected to that crest. The number of curved surfaces D is equal to the number of wave crests of the single-waveform wave rod 1122. Further, refer to... Figure 8, for the projection of any wave rod 1122 on the curved surface D (i.e., the waveform 1123), the distance between its projection on the same curved surface as the axis (i.e., the axis) increases first and then decreases, or increases first and then remains unchanged from the wave crest to the wave trough. That is to say, the distance L1 from the position near the wave crest to the axis is less than the distance L2 from the position between the wave crest and the wave trough to the axis, and L2 is less than or equal to the distance L3 from the position near the wave trough to the axis.

[0056] L1 < L2 ≤ L3. Such a setting ensures the consistency and symmetry of the bare stent segment 112, making the bare stent segment 112 have uniform radial supporting force.

[0057] Second Embodiment

[0058] Refer to Figure 9 , Figure 9 is a schematic structural view of the covered stent 20 of the second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the covered stent 20 does not have a strictly defined bare stent segment, and a film 22 is also provided between the proximal wave loops 212 and the main body wave loops 211 of the covered stent 20. This embodiment has a better effect of isolating blood compared with the first embodiment.

[0059] Third Embodiment

[0060] This embodiment is for the use of the covered stent in the aortic arch. Refer to Figure 10 , Figure 10 is a schematic view of the working state of the covered stent 30 of the third embodiment of the present invention. The difference between the third embodiment and the first embodiment is that the covered stent 30 includes a first wave rod 3121 and a second wave rod 3122 disposed opposite to the first wave rod 3121. When the covered stent is implanted in the aortic arch, due to the importance of the upper branch vessels, the covered stent 30 must not block the branch vessels. Therefore, the proximal end of the film of the covered stent 30 needs to be accurately positioned at the edge of the branch vessels. Since the distal end of the first wave rod 3121 protrudes and the proximal end is concave, the bare stent segment 312 partially extends into the branch vessels at the position near the branch vessels, making the wave loop where the first wave rod 3121 is located abut and anchor at the opening of the branch vessels, increasing the overall stability of the covered stent 30. In addition, since the extending direction of the first wave rod 3121 is consistent with the extending direction of the aortic arch, the proximal end of the first wave rod 3121 does not abut against the inner wall of the blood vessel at the aortic arch position.

[0061] On this basis, reducing the offset of the proximal and distal ends of the second wave rod 3122 (i.e., the degree of concavity of the proximal end and the degree of protrusion of the distal end) can better adapt to the bending state of the aortic arch.

[0062] It should be noted that although the extension direction of the second wave rod 3122 is not the same as the extension direction of the aortic arch, since the second wave rod 3122 is set opposite to the first wave rod 321, the proximal end of the second wave rod 3122 will not abut against the inner wall of the blood vessel at the aortic arch position.

[0063] In another embodiment, the second wave bar follows the extension direction of the aortic arch, that is, the second wave bar is parallel to the axis of the covered stent in its natural state, or extends outward relative to the axis of the covered stent.

[0064] In another embodiment, the second wave rod follows the extension direction of the aortic arch, with the proximal end of the second wave rod offset inward relative to the axis of the covered stent in its natural state, and the distal end of the second wave rod offset outward relative to the axis of the covered stent in its natural state.

[0065] Therefore, in addition to the first wave rod 3121, the bare stent segment 312 of the covered stent 30 may include a second wave rod 3122 that extends in the same direction as the first wave rod 3121 but with different degrees of deflection (i.e., different angles and distances of extension) and / or different directions of extension.

[0066] Fourth embodiment

[0067] This embodiment demonstrates the use of a covered stent in conjunction with a small stent, as described in the following reference. Figure 11-12 , Figure 11 This is a schematic diagram of the operation of a straight bare stent covered stent 90mm in conjunction with a small stent. Figure 12 This is a schematic diagram of the working of the film-coated stent 40 in conjunction with the small stent in this embodiment.

[0068] For the straight bare stent covered stent 90, the small stent 80 compresses the proximal end of the covered stent segment 911, causing the proximal end of the covered stent segment 911 to indent inward. This causes the distal end of the bare stent segment 912 to move towards the axis of the straight covered stent 90. Due to the natural outward expansion of the straight covered stent 90, the bare stent segment 912 deforms. The proximal end of the bare stent 912 abuts against the vessel wall, causing compression. Because the contact between the proximal end of the bare stent segment 912 and the vessel wall is point contact, the proximal end of the bare stent segment 912 exerts significant pressure on the vessel wall, which can easily damage the vessel wall.

[0069] For the covered stent 40 in this embodiment, the small stent 80 also compresses the proximal end of the covered stent segment 411, causing the proximal end of the covered stent segment 411 to indent inward. This, in turn, causes the distal end of the first wave rod 4121 on the bare stent segment 412 to move toward the axis of the covered stent 40, resulting in deformation of the bare stent segment 412. The deformation of the first wave rod 4121 has the following characteristics:

[0070] 1. The distal end of the first wave rod 4121 moves toward the axis of the film-coated support 40 under the pressure of the small support 80, and the pressure is transmitted along the rod body of the first wave rod 4121.

[0071] 2. The proximal end of the first wave rod 4121 moves along the axis of the distal end toward the covered support 40. At this time, the proximal end of the first wave rod 4121 is deflected by the force transmitted from the distal end of the rod. When the external force and the elastic force of the self-expansion of the first wave rod 4121 are in balance, the relative position of the proximal end of the first wave rod 4121 to the distal end is more outward than in the natural state, that is, the proximal end of the first wave rod 4121 will deflect outward.

[0072] Based on the above characteristics, the proximal end of the first wave rod 4121 will deflect outwards. However, since the rate of change of the distance from the first wave rod 4121 to the axis changes from positive to negative from the distal end to the proximal end, that is, the distal end of the first wave rod 4121 extends outwards and the proximal end extends inwards, the proximal end of the first wave rod 4121 will deflect in a horizontal direction when it deflects outwards. There will be no point contact between the proximal end of the bare stent segment 412 and the vessel wall. In other words, from the proximal end to the distal end of the first wave rod 4121, there is at least one segment of the wave rod whose tangent is parallel to the axis, so that the proximal end of the bare stent segment 412 will never collide or squeeze with the vessel wall, which can effectively prevent damage to the vessel wall.

[0073] Fifth embodiment

[0074] Compared to the first embodiment, refer to Figure 13-14 The covered stent 50 includes a covered stent segment 511 and a bare stent segment 512. The bare stent segment 512 includes a first segment 5121 and a second segment 5122. The first segment 5121 and the second segment 5122 are arranged opposite to each other. The axial length of the first segment 5121 is greater than the axial length of the second segment 5122. Specifically, the axial length of the first segment 5121 is at least 1.5 times greater than the axial length of the second segment 5122.

[0075] Combination Figure 15-16 , Figure 15 This is a schematic diagram of the initial stage of the covered stent 50 being released at a predetermined position through the sheath in this embodiment. Figure 16This is a schematic diagram of the final stage of the covered stent 50 being released at a predetermined position through the sheath in this embodiment. During deployment, the bare stent segment 512 of the covered stent 50 is fixed at the TIP tip 520 of the sheath. The first segment 5121 is closer to the greater curvature of the aortic arch, and the second segment 5122 is closer to the lesser curvature of the aortic arch. Since the axial length of the first segment 5121 is greater than that of the second segment 5122, the positions of the first segment 5121 and the second segment 5122 at the TIP tip 520 will be biased towards the second segment 5122. When leaving the TIP tip 520, the second segment 5122 on the lesser curvature side has a shorter stroke to return to its expanded state, resulting in less impact on the lesser curvature side and better protection of the vascular wall. In addition, the first segment 5121 on the greater curvature side is longer. During deployment, the distal end of the first segment 5121 contacts the greater curvature side first, and due to the curvature of the blood vessel on the greater curvature side, the free end (i.e., the proximal end) of the first segment 5121 is prevented from impacting the blood vessel.

[0076] Sixth Embodiment

[0077] Compared to the first embodiment, refer to Figure 17-19 The covered stent 60 includes a covered stent segment 611 and a bare stent segment 612. The bare stent segment 612 includes a plurality of alternately arranged third wave rods 6121 and fourth wave rods 6122. The third wave rods 6121 and fourth wave rods 6122 have the same structural properties as the first wave rod in the first embodiment. The difference is that the plurality of alternately arranged third wave rods 6121 and fourth wave rods 6122 form a grid structure. The grid structure of the third wave rods 6121 and fourth wave rods 6122 simultaneously satisfies that, viewed from the distal end to the proximal end, the third wave rods 6121 and fourth wave rods 6122 first extend outward and then extend inward. Therefore, the rate of change of the distance of the third wave rods 6121 and fourth wave rods 6122 from the axis changes from a positive value to a negative value (positive value increases, negative value decreases) from the distal end to the proximal end. In other words, the third wave rod 6121 and the fourth wave rod 6122 each have protrusions to support the blood vessel wall after the covered stent 60 is released. In this embodiment, the intersection of the third wave rod 6121 and the fourth wave rod 6122 is located at the apex of the protrusions of the third wave rod 6121 and the fourth wave rod 6122. When the covered stent 60 is released, the intersection is the point where the stress of the covered stent 60 on the blood vessel wall is most concentrated. The stress at the intersection is distributed in two directions along the third wave rod 6121 and the fourth wave rod 6122, thereby avoiding the problem of excessive stress concentration and damage to the blood vessel wall caused by the third wave rod 6121 and the fourth wave rod 6122 acting alone.

[0078] Furthermore, the third wave rod 6121 and the fourth wave rod 6122 overlap each other. In their natural state, the intersection of the third wave rod 6121 and the fourth wave rod 6122 is also located at the apex of the protrusions of the third wave rod 6121 and the fourth wave rod 6122. After the covered stent 60 is released, the third wave rod 6121 and the fourth wave rod 6122 are deformed under pressure, and the stress concentration point is located at the intersection. At this time, due to the overlap, the third wave rod 6121 and the fourth wave rod 6122 will undergo adaptive deformation, thereby changing the position of the intersection point, thus better adapting to the complex environment within the blood vessel. At the same time, the third wave rod 6121 and the fourth wave rod 6122 can support each other, providing necessary support for the covered stent 60. The application environment of the covered stent 60 in this embodiment includes blood vessels with complex bends, such as the aortic arch. The structure of the overlapping and movable third wave rod 6121 and the fourth wave rod 6122 has better environmental adaptability.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A covered stent comprising a stent body, the stent body comprising a first stent segment and a second stent segment connected proximally to the first stent segment, the first stent segment comprising a covering, characterized in that, The second stent segment includes at least one first wave rod, wherein at least a portion of the distal end of the first wave rod is at a distance greater than the distance from the proximal end of the first wave rod to the axis of the covered stent, wherein the absolute value of the rate of change of the distance from the distal end of the first wave rod to the proximal end of the first wave rod first increases and then decreases. The first wave rod includes at least a first segment near the proximal end and a second segment near the distal end, with the first segment and the second segment extending in opposite directions along the axis. The first segment is located inside the first support segment, and the second segment is located outside the first support segment.

2. The covered stent according to claim 1, characterized in that, The second support segment includes a first band and a second band, which are arranged opposite to each other, and the axial length of the first band is greater than the axial length of the second band.

3. The covered stent according to claim 1, characterized in that, The second support segment includes a second wave rod. The second wave rod extends in the same direction as the first wave rod, but the degree of deflection is different; or the second wave rod extends in a different direction than the first wave rod, but the degree of deflection is the same; or the second wave rod extends in a different direction than the first wave rod, and the degree of deflection is also different.

4. The covered stent according to claim 1, characterized in that, The second support segment includes a third wave rod and a fourth wave rod, which are interwoven to form a mesh structure. The third wave rod and the fourth wave rod each include a first protrusion and a second protrusion. The intersection of the third wave rod and the fourth wave rod is located at the maximum protrusion position of both the first protrusion and the second protrusion.

5. A combined support, characterized in that, The covered stent, including any one of claims 1-4, further includes a small stent, the small stent pressing against and abutting the proximal end of the first stent segment from the outside in, the proximal end of the covered stent of the small stent being flush with the proximal end of the covered stent of the first stent segment, and at least one segment from the proximal end of the second stent segment to the distal end of the second stent segment near the small stent having a tangential direction parallel to the axis.

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