Stent Delivery System

Abstract

The present application discloses a stent delivery system, including a tip, a sheath core tube, a self-expanding stent, and an outer sheath tube. The tip is disposed at one end of the sheath core tube. The sheath core tube is disposed within the outer sheath tube. The stent is sleeved on the sheath core tube, and the stent is located between the sheath core tube and the outer sheath tube. The system further includes a first soft gasket and a second soft gasket. Both the first soft gasket and the second soft gasket are disposed on the sheath core tube. The first soft gasket is located between the second soft gasket and the tip. The first soft gasket and the second soft gasket are located between the stent and the outer sheath tube. The sizes of the first soft gasket and the second soft gasket are not equal. The circumferential arc degrees of the first soft gasket and the second soft gasket covering the sheath core tube are both greater than 180 degrees. The spacing distance between the first soft gasket and the second soft gasket is greater than 0.1 mm and less than 30 mm. The stent includes a bare section and a covered section. When the stent is within the outer sheath tube.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and particularly to a stent delivery system. Background Art

[0002] A stent device is a tubular vascular implant having a structure capable of supporting a section of blood vessel or other anatomical lumen to prevent collapse; at the same time, it allows blood or other body fluids to flow through the lumen of the stent device. The stent device is delivered to the location of the diseased section of blood vessel by a delivery catheter and is deployed there to support the blood vessel to prevent radial collapse. The stent device enters the location within the collapsed structure and expands to contact the inner wall of the blood vessel when deployed.

[0003] The PCT patent document with publication number WO0071058A1 discloses a stent delivery system. This stent delivery system proposes to arrange a series of soft protrusion structures on the sheath core tube in the region near the head end, so as to engage with the corrugated metal frame of the self-expanding stent device, in order to block the displacement or axial compression and stacking behavior of the stent device when withdrawing the outer sheath to release the self-expanding stent device. For a stent device having both a bare stent section and a covered stent section, these protrusion structures engaging with the corrugated metal frame are likely to damage / puncture the covered structure; and in actual use, these protrusion structures engaging with the corrugated metal frame will also significantly increase the stent release force of the delivery system (i.e., the resistance when the outer sheath slides relative to the stent device), which seriously affects the operator's handling feel and sensitivity during the operation, distracting the operator and thus affecting the operation quality.

[0004] The PCT patent document with publication number WO2010031755A1 discloses a stent device delivery system, which proposes to axially arrange a series of sheet-like viscous materials providing viscosity on the sheath core tube in the region near the head end, so that the stent device is adhered to the sheet-like viscous materials, in order to block the relatively large displacement or axial compression and stacking behavior of the stent device when withdrawing the outer sheath to release the self-expanding stent device. However, due to the viscous characteristics of the sheet-like viscous materials in this design, they will still have an adhesive effect on the outer sheath, thus significantly increasing the stent release force of the delivery system. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a stent delivery system.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A stent delivery system includes a tip, a sheath core tube, a self-expanding stent, and an outer sheath tube. The tip is disposed at one end of the sheath core tube. The sheath core tube is disposed within the outer sheath tube. The stent is sleeved on the sheath core tube and is located between the sheath core tube and the outer sheath tube. It further includes a first soft gasket and a second soft gasket. Both the first soft gasket and the second soft gasket are disposed on the sheath core tube. The first soft gasket is located between the second soft gasket and the tip. The first soft gasket and the second soft gasket are located between the stent and the outer sheath tube. The sizes of the first soft gasket and the second soft gasket are not equal. The circumferential arc of the sheath core tube covered by the first soft gasket and the second soft gasket is greater than 180 degrees. The spacing distance between the first soft gasket and the second soft gasket is greater than 0.1 mm and less than 30 mm. The stent includes a bare segment and a membrane-covered segment. When the stent is within the outer sheath tube, the second soft gasket presses against a part of the membrane-covered segment, and the first soft gasket presses against the bare segment.

[0008] It should be noted that the main structure of the stent is a frame, and the frame is made of a shape memory metal. The part of the frame without a membrane is the bare segment (i.e., the frame itself can be regarded as the bare segment), and the part of the frame with a membrane is the membrane-covered segment.

[0009] In this stent delivery system, when the stent is completely within the outer sheath tube, the first soft gasket presses against the bare segment of the stent, and the second soft gasket presses against a part of the membrane-covered segment of the stent. When the inner sheath core with the stent exits the outer sheath tube, the first soft gasket leaves the outer sheath tube first, and the second soft gasket leaves the outer sheath tube later. When the stent is within the outer sheath tube, the stent is in a compressed state, and when the stent exits the outer sheath tube, the stent has a tendency to expand and return to its natural state.

[0010] In this stent delivery system, when the stent is completely within the outer sheath tube, the first soft gasket and the second soft gasket have a tendency to push the stent against the inner wall of the outer sheath tube. Therefore, the presence of the first soft gasket and the second soft gasket can prevent the stent within the outer sheath tube from stacking. When this stent delivery system is in use, the inner sheath core (together with the stent) is in a fixed state, and the outer sheath tube slides relative to the inner sheath core under the action of an external force, so that the inner sheath core gradually slides out relative to the outer sheath tube. During the sliding out process, since the first soft gasket and the second soft gasket have a tendency to push the stent against the inner wall of the outer sheath tube, the contact area between the stent and the inner wall of the outer sheath tube also decreases during the sliding out process, and the frictional resistance (i.e., the release resistance during the stent release process) received by the outer sheath tube also gradually decreases, making the release resistance during the stent release process gradually decrease.

[0011] In this middle stent delivery system, there is a gap between the first soft gasket and the end, and the gap distance is greater than 1 mm and less than 35 mm. The length of the exposed section is equal to the sum of the length of the first soft gasket and the gap distance value, which means that the friction between the stent at the first soft gasket and the inner wall of the outer sheath is less than the friction between the second soft gasket and the inner wall of the outer sheath. This can reduce the frictional resistance borne by the outer sheath when the outer sheath starts to slide for the first time (i.e., the release resistance during the stent release process).

[0012] Specifically, the frame can be formed by linking several waveform winding wire units; it can also be woven from open waveform winding wire units. The covered section and the exposed section are smoothly connected, and the connection method is loop buckling. The entire exposed section (near the end) is constricted and pressed onto the first soft gasket, and a part of the covered section is constricted and pressed onto the second soft gasket.

[0013] In summary, in the above delivery system, through the setting of the first soft gasket and the second soft gasket, the stacking of the stent on the inner wall of the outer sheath is avoided, and the release resistance during the release process is small.

[0014] Optionally, a ramp portion is provided on the second soft gasket, and the ramp portion is located at one end of the second soft gasket close to the first soft gasket.

[0015] The introduction of the ramp portion can further reduce the release resistance when the stent is released.

[0016] Optionally, the hardness of the ramp portion is greater than the hardness of other parts of the second soft gasket.

[0017] The hardness of the ramp portion being greater than the hardness of other parts of the second soft gasket can, on the one hand, further reduce the release resistance when the stent is released, and on the other hand, can prevent the frame winding wire from getting stuck and causing damage to the film.

[0018] Optionally, the covered section of the stent includes a frame and a film, the film is attached to the frame, and the exposed section of the stent includes a frame.

[0019] The frame is the general structure of the stent, the framework is the exposed section of the stent, and the film part on the framework is the covered section of the stent.

[0020] Optionally, the frame is a cylindrical helical spring or a conical helical spring or a double-cone helical spring.

[0021] Optionally, the winding wire of the frame is a waveform winding wire or a linear winding wire.

[0022] Optionally, a radiopaque ring is provided in the connection area between the covered section and the exposed section, and the cross-sectional diameter of the radiopaque ring is smaller than the cross-sectional diameter of the stent.

[0023] Since the developing ring and the frame are made of different metals and the cross-sectional diameter of the developing ring is smaller than that of the stent (i.e., the frame), when the developing ring is located inside the outer sheath tube, the developing ring does not contact the inner wall of the outer sheath tube, so the developing ring does not affect the release resistance during stent release.

[0024] Specifically, the developing ring is located between the first soft gasket and the second soft gasket.

[0025] Optionally, a radiopaque film is provided inside the covered film section.

[0026] Specifically, the radiopaque film is provided on the covered film section to show the position of the stent. Specifically, both the developing ring and the radiopaque film can be made of gold.

[0027] Optionally, a push rod is further included, and the push rod is arranged inside the outer sheath tube.

[0028] Optionally, a handle assembly is further included, and the handle assembly is cooperated with the outer sheath tube.

[0029] Specifically, the push rod is fixedly connected to the handle assembly, and the length interval between the push rod and the end is used to place the stent. The function of the handle assembly is to drive the outer sheath tube to move relative to the inner sheath core.

[0030] The beneficial effects of the present invention are: through the arrangement of the first soft gasket and the second soft gasket, the stacking of the stent on the inner wall of the outer sheath tube is avoided, and at the same time, the release resistance during the release process is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the state where the stent of the stent delivery system is completely located inside the outer sheath tube;

[0032] Figure 2 is Figure 1 an enlarged schematic diagram of part A in

[0033] Figure 3 is Figure 2 a schematic cross-sectional diagram perpendicular to the axial direction of the first soft gasket in

[0034] Figure 4 is Figure 2 a schematic cross-sectional diagram perpendicular to the axial direction of the second soft gasket in

[0035] Figure 5 is Figure 2 a schematic cross-sectional diagram in the axial direction of the second soft gasket in

[0036] Figure 6 is Figure 1 an enlarged schematic diagram of part B in

[0037] Figure 7 is a schematic diagram of the state where the stent of the stent delivery system begins to leave the outer sheath tube;

[0038] Figure 8 is Figure 4 a schematic enlarged view of the C position in the middle;

[0039] Figure 9 is a schematic structural view of the stent;

[0040] Figure 10 is a schematic view of an embodiment of the arrangement of the soft gasket on the inner sheath core;

[0041] Figure 11 is a schematic view of an embodiment of the inner sheath core with a ramp portion and a soft gasket;

[0042] Figure 12 is a schematic view of an embodiment of the inner sheath core with a stepped soft gasket;

[0043] Figure 13 is a schematic cross-sectional view of the handle assembly of the stent delivery system in some embodiments.

[0044] The reference numerals in the figure are: 1, end; 2, outer sheath tube; 3, push rod; 4, inner sheath core; 501, exposed section; 5011, exposed section support rod; 502, film-covered section; 5021, film-covered section support rod; 5022, film; 503, radiopaque ring; 601, first soft gasket; 6011, first soft gasket lower step; 6012, first soft gasket upper step; 602, second soft gasket; 6021, second soft gasket lower step; 6021, second soft gasket upper step; 6021, ramp portion; L1, first soft gasket length; L2, spacing between the first soft gasket and the second soft gasket; L3, second soft gasket length; L4, first soft gasket height; L5, second soft gasket height; L11, first soft gasket lower step length; L12, first soft gasket upper step length; L31, second soft gasket lower step length; L32, second soft gasket upper step length. Detailed implementation manners

[0045] The present invention will be described in detail below with reference to the accompanying drawings.

[0046] As shown in the attached Figure 1 to the attached Figure 8 and the attached Figure 10As shown, a stent delivery system includes a tip 1, a sheath core tube, a self-expanding stent, and an outer sheath tube 2. The tip 1 is disposed at one end of the sheath core tube. The sheath core tube is disposed within the outer sheath tube 2. The stent is sleeved on the sheath core tube, and the stent is located between the sheath core tube and the outer sheath tube 2. It further includes a first soft gasket 601 and a second soft gasket 602. Both the first soft gasket 601 and the second soft gasket 602 are disposed on the sheath core tube. The first soft gasket 601 is located between the second soft gasket 602 and the tip 1. The first soft gasket 601 and the second soft gasket 602 are located between the stent and the outer sheath tube 2. The sizes of the first soft gasket 601 and the second soft gasket 602 are not equal (the unequal sizes refer to the length of the soft gasket along the axial direction of the sheath core tube and the thickness in the direction perpendicular to the sheath core tube). The circumferential arcs of the first soft gasket 601 and the second soft gasket 602 covering the sheath core tube are both greater than 180 degrees. The spacing distance L2 between the first soft gasket 601 and the second soft gasket 602 is greater than 0.1 mm and less than 30 mm. The stent includes a bare section 501 and a membrane-covered section 502. The bare section 501 includes bare section support rods 5011. The membrane-covered section 502 includes membrane-covered section support rods 5021 and a membrane 5022. The length L3 of the second soft gasket is less than the length of the membrane-covered section 502. When the stent is within the outer sheath tube 2, a part of the membrane-covered section 502 abuts and presses against the second soft gasket 602, and the bare section 501 abuts and presses against the first soft gasket 601. After a soft gasket with a certain thickness is pressed, the part in contact with the support rod undergoes conformable elastic deformation, as Figure 3 and Figure 5 shown, the support rod sinks into the soft gasket.

[0047] It should be noted that the main structure of the stent is a frame. The frame is made of a shape memory metal. The part of the frame without a membrane is the bare section 501 (i.e., the frame itself can be regarded as the bare section 501), and the part of the frame with a membrane is the membrane-covered section 502. In this stent delivery system, when the stent is completely within the outer sheath tube 2 (this state is as shown in the appendix Figure 1 ), the first soft gasket 601 abuts against the bare section 501 of the stent, and the second soft gasket 602 abuts against a part of the membrane-covered section 502 of the stent. When the inner sheath core 4 takes the stent out of the outer sheath tube 2, the support rod sunk into the soft gasket will not undergo position slippage with the relative sliding of the outer sheath tube 2. The first soft gasket 601 leaves the outer sheath tube 2 first (this state is as shown in the appendix Figure 7 ), and the second soft gasket 602 leaves the outer sheath tube 2 later. When the stent is within the outer sheath tube 2, the stent is in a compressed state, and when the stent leaves the outer sheath tube 2, the stent has a tendency to expand by itself and return to its natural state.

[0048] In this middle stent delivery system, when the stent is fully within the outer sheath tube 2, the first soft gasket 601 and the second soft gasket 602 tend to push the stent against the inner wall of the outer sheath tube 2. Therefore, the presence of the first soft gasket 601 and the second soft gasket 602 can prevent the stents within the outer sheath tube 2 from stacking. The stacking of stents causes a certain radial cross-section in the space between the inner and outer sheath tubes to be over-saturated; the adverse effect of this over-saturation is that the resistance to the relative movement between the inner and outer sheath tubes increases sharply, and most of this resistance comes from the force exerted by the stacked part of the stents on the inner and outer sheath tubes; as the stacking degree intensifies, the force exerted by the stacked part of the stents on the inner and outer sheath tubes becomes greater, resulting in a sharp increase in the stent release resistance, which is not conducive to the stent release operation. When this stent delivery system is in use, the inner sheath core 4 (together with the stent) is in a fixed state, while the outer sheath tube 2 slides relative to the inner sheath core 4 under the action of an external force, so that the inner sheath core 4 gradually slides out relative to the outer sheath tube 2. During the sliding out process, since the first soft gasket 601 and the second soft gasket 602 tend to push the stent against the inner wall of the outer sheath tube 2, the stacking of the stents within the outer sheath tube 2 is avoided. However, inappropriate soft gasket design and arrangement will still cause an increase in the stent release resistance. This stent delivery system is further improved by arranging the first soft gasket 601 and the second soft gasket 602 at intervals and adding a differential design in terms of size at the same time, so that the force exerted by the soft gaskets to push the stent support rod against the inner wall of the outer sheath tube 2 shows a dot matrix-like strong and weak distribution along the axial and circumferential directions. It can be understood that this design of the force distribution with a dot matrix-like strong and weak effect along the axial and circumferential directions can optimize the force exerted by the stent support rod against the inner wall of the outer sheath tube 2 after the introduction of the soft gaskets to reduce redundant forces; on the other hand, the contact area between the stent and the inner wall of the outer sheath tube 2 is also reduced, and the frictional resistance received by the outer sheath tube 2 (i.e., the release resistance during the stent release process) is gradually reduced, making the release resistance gradually decrease during the stent release process.

[0049] The differential design of the soft gasket in terms of size can be either a difference design in length or a difference design in thickness; for example, the length L1 of the first soft gasket 601 along the axial direction of the sheath core tube is not equal to the length L3 of the second soft gasket 602 along the axial direction of the sheath core tube, and the thickness L4 of the first soft gasket 601 is not equal to the thickness L5 of the second soft gasket 602. The length L1 of the first soft gasket 601 along the axial direction of the sheath core tube is greater than the length L3 of the second soft gasket 602 along the axial direction of the sheath core tube. The thickness L4 of the first soft gasket 601 is greater than the thickness L5 of the second soft gasket 602. The length L3 of the second soft gasket 602 is less than 0.5 times the length of the coated section 502. The length L3 of the second soft gasket 602 is less than 20 mm. The thickness L4 of the first soft gasket 601 is less than 2 mm.

[0050] In some embodiments, there is a gap (not shown in the figure) between the first soft gasket 601 and the end 1, and the gap distance is greater than 1 mm and less than 35 mm. The length of the exposed section 501 is equal to the sum of the length of the first soft gasket 601 and the gap distance value, which means that the frictional force between the stent at the first soft gasket 601 and the inner wall of the outer sheath tube 2 is less than the frictional force between the second soft gasket 602 and the inner wall of the outer sheath tube 2. In this way, the frictional resistance borne by the outer sheath tube 2 when it starts to slide (i.e., the release resistance during the stent release process) can be reduced.

[0051] In some embodiments, the thickness L4 of the first soft gasket 601 is greater than the thickness L5 of the second soft gasket 602 to avoid excessive extrusion of the film 5022 of the film-covered section 502 by the second soft gasket 602, as Figure 5 shown.

[0052] The specific stent frame can be formed by linking a plurality of waveform-wrapping wire units; it can also be woven from open waveform-wrapping wire units. The film-covered section 502 and the exposed section 501 are smoothly connected in a way of loop connection. The exposed section 501 (near the end 1) is all bundled and a part of it is pressed on the first soft gasket 601, and a part of the film-covered section 502 is bundled and pressed on the second soft gasket 602.

[0053] In summary, through the settings of the first soft gasket 601 and the second soft gasket 602 in the above-mentioned delivery system, the stacking of the stent on the inner wall of the outer sheath tube 2 is avoided, and the release resistance during the release process is small.

[0054] As shown in the appendix Figures 1 to 8 and Figure 11 shown, a ramp portion 6021 is provided on the second soft gasket 602, and the ramp portion 6021 is located at one end of the second soft gasket 602 close to the first soft gasket 601.

[0055] The introduction of the ramp portion 6021 can further reduce the release resistance when the stent is released.

[0056] As shown in the appendix Figure 1 to the appendix Figure 8 and the appendix Figure 11 shown, the hardness of the ramp portion 6021 is greater than the hardness of other parts of the second soft gasket 602. The material of the ramp portion 6021 is different from the material of the second soft gasket 602.

[0057] The material of the ramp portion 6021 is different from the materials of the first soft gasket 601 and the second soft gasket 602.

[0058] The material of the slope part 6021 is one or a combination of the following: UV glue, thermoplastic polyurethane elastomer rubber, fluorinated ethylene propylene, polyolefin, PVC, PU, TPE, nylon.

[0059] If the hardness of the slope part 6021 is greater than that of other parts on the second soft gasket 602, on the one hand, the release resistance during stent release can be further reduced, and on the other hand, the damage of the film caused by the winding wire of the stent frame getting stuck can be avoided.

[0060] As shown in the attached Figure 1 to the attached Figure 9 As shown, the film-covered section 502 of the stent includes a frame and a film, the film is attached to the frame, and the frame is composed of corrugated spiral film-covered section support rods 5021; the bare section 501 of the stent includes a frame, and the frame is composed of woven bare section support rods 5011.

[0061] The frame is the general structure of the stent. The framework is the bare section 501 of the stent, and the film-covered part on the framework is the film-covered section 502 of the stent.

[0062] As shown in the attached Figure 1 to the attached Figure 9 As shown, the frame is a cylindrical spiral spring or a conical spiral spring or a double-cone spiral spring.

[0063] As shown in the attached Figure 1 to the attached Figure 9 As shown, the winding wire of the frame is a corrugated winding wire or a linear winding wire.

[0064] As shown in the attached Figure 1 to the attached Figure 9 As shown, a radiopaque ring 503 is provided in the connection area between the film-covered section 502 and the bare section 501. The cross-sectional diameter of the radiopaque ring 503 is smaller than the cross-sectional diameter of the stent. The cross-sectional diameter is less than or equal to the thickness of the film.

[0065] Because the radiopaque ring 503 and the frame are made of different metals, and the cross-sectional diameter of the radiopaque ring 503 is smaller than the cross-sectional diameter of the stent (i.e., the frame), when the radiopaque ring 503 is located in the outer sheath 2, the radiopaque ring 503 does not contact the inner wall of the outer sheath 2, so the radiopaque ring 503 does not affect the release resistance during stent release.

[0066] Specifically, the radiopaque ring 503 is located between the first soft gasket 601 and the second soft gasket 602.

[0067] As shown in the attached Figure 1 to the attached Figure 9 As shown, a radiopaque film is provided in the film-covered section 502.

[0068] The radiographic film is provided on the specific film covering section 502 to show the position of the stent. The specific radiographic ring 503 and the radiographic film can both be made of gold.

[0069] As shown in the Figure 1 to the Figure 9 accompanying drawings, it further includes a push rod 3, and the push rod 3 is arranged inside the outer sheath tube 2.

[0070] As shown in the Figure 1 to the Figure 9 and the Figure 13 accompanying drawings, it further includes a handle assembly, and the handle assembly is fitted with the outer sheath tube 2.

[0071] Specifically, the push rod 3 is fixedly connected to the handle assembly, and the length interval between the push rod 3 and the end 1 is used to place the stent. The function of the handle assembly is to drive the outer sheath tube 2 to move relative to the inner sheath core 4.

[0072] The handle assembly can also adopt the handle assemblies disclosed in CN103505311B or CN110368160A.

[0073] In the stent delivery system provided in this embodiment, compared with the currently common stent delivery systems on the market (the specification model is T06802075), a first soft gasket and a second soft gasket are added. Therefore, further comparison of the release resistance of T06802075 before and after improvement (i.e., before and after adding the soft gaskets) is carried out. For the convenience of presenting data, a total of two specifications of stents, 6X100 and 8X100, are selected for the test. The test results are shown in the following table.

[0074]

[0075] In some embodiments, as shown in the Figure 12 accompanying drawings, the first soft gasket 601 and the second soft gasket 602 are respectively arranged in a stepped manner, that is, the first soft gasket 601 includes a first soft gasket lower-order part 6011 and a first soft gasket higher-order part 6012; the second soft gasket 602 includes a second soft gasket lower-order part 6021 and a second soft gasket higher-order part 6021. The length L11 of the first soft gasket lower-order part 6011 is greater than the length of the first soft gasket higher-order part 6012; the thickness of the lower-order part is less than the thickness of the higher-order part; the length of the second soft gasket lower-order part 6021 is greater than the length of the second soft gasket higher-order part 6021. It can be understood that such a design makes the acting force of the soft gasket pushing the stent support rod against the inner wall of the outer sheath tube 2 show a dot matrix-like strong and weak distribution along the axial and circumferential directions.

[0076] In some embodiments, the first soft gasket 601 and the second soft gasket 602 are made of different materials. It can be understood that the material differentiation of the soft gasket is beneficial to the force exerted by the soft gasket to push the support strut against the inner wall of the outer sheath 2 to show a dot matrix-like strong and weak distribution along the axial and circumferential directions. The material of the first soft gasket is one or a combination of the following: fluorinated ethylene propylene, polyolefin, silicone, PVC, TPU, PU, nylon.

[0077] The above are only the preferred embodiments of the present invention, and thus do not limit the patent protection scope of the present invention. Any equivalent transformation made by using the content of the specification of the present invention, directly or indirectly applied in other related technical fields, shall be equally included in the protection scope of the present invention.

Claims

1. A stent delivery system, comprising a tip, a sheath core tube, a self-expanding stent, and an outer sheath tube, wherein the tip is disposed at one end of the sheath core tube, the sheath core tube is disposed within the outer sheath tube, the stent is sleeved on the sheath core tube, and the stent is located between the sheath core tube and the outer sheath tube, and is characterized in that, It further includes a first soft gasket and a second soft gasket. Both the first soft gasket and the second soft gasket are arranged on the sheath core tube. The first soft gasket is located between the second soft gasket and the end. The first soft gasket and the second soft gasket are located between the stent and the outer sheath tube. The sizes of the first soft gasket and the second soft gasket are not equal. The circumferential coverage arc of the first soft gasket and the second soft gasket on the sheath core tube is greater than 180 degrees. The spacing distance between the first soft gasket and the second soft gasket is greater than 0.1 mm and less than 30 mm. The stent includes a bare section and a film-covered section. When the stent is inside the outer sheath tube, the second soft gasket is in close contact with a part of the film-covered section, and the first soft gasket is in close contact with the bare section.

2. The stent delivery system according to claim 1, wherein, A ramp portion is provided on the second soft gasket, and the ramp portion is located at one end of the second soft gasket close to the first soft gasket.

3. The stent delivery system according to claim 2, wherein, The hardness of the ramp portion is greater than the hardness of other parts on the second soft gasket.

4. The stent delivery system according to claim 1, wherein, There is a spacing between the first soft gasket and the end, and the spacing distance is greater than 1 mm and less than 35 mm. The length of the bare section is equal to the sum of the length of the first soft gasket and the spacing distance value.

5. The stent delivery system according to claim 4, wherein, The length of the first soft gasket is not equal to the length of the second soft gasket, and the length of the second soft gasket is less than 0.5 times the length of the film-covered section.

6. The stent delivery system according to claim 4, wherein The thickness of the first soft gasket is not equal to the thickness of the second soft gasket, and the thickness of the first soft gasket is less than 2 mm.

7. The stent delivery system according to claim 1, wherein The first soft gasket includes a first soft gasket low-order part and a first soft gasket high-order part. The second soft gasket includes a second soft gasket low-order part and a second soft gasket high-order part. The thickness of the low-order part is less than the thickness of the high-order part.

8. The stent delivery system according to claim 7, wherein The length of the first soft gasket low-order part is greater than the length of the first soft gasket high-order part.

9. The stent delivery system according to claim 1, wherein, The materials of the first soft gasket and the second soft gasket are different.

10. The stent delivery system according to claim 9, wherein, The first soft gasket is made of one or a combination of the following materials: fluorinated ethylene propylene copolymer, polyolefin, silica gel, PVC, TPU, PU, nylon.

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