Expandable sheath and support structure thereof

Abstract

The supporting structure for expanding the sheath comprises a support, the support is provided with a main body part and a connecting part, the main body part expands in the radial direction under the action of external force and contracts in the radial direction after the external force is removed, and the main body part comprises a fixing rib extending in the axial direction so as to limit the axial length of the main body part. The connecting part is arranged at the near end of the fixing rib and used for being in butt joint with an external assembly, and a limiting structure is arranged between the connecting part and the external assembly. When an external instrument penetrates into or withdraws from the stent, one part of the main body part is stressed to move in the axial direction, at the moment, the inner surface of the stent covering film is subjected to friction stress in the axial direction, the friction stress is generated by conveying force, and the other part of the friction stress is limited by the limiting structure in the axial direction and keeps static relative to an operator. The main body part is kept static and matched with corresponding axial friction stress, so that the main body part can be expanded in the conveying (withdrawing) process, the conveying (withdrawing) force of an instrument is reduced, and the passing difficulty of the instrument in the expandable sheath is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of medical devices, and in particular to an expandable sheath and its supporting structure. Background Art

[0002] In recent years, mechanical circulatory assistance has become an important treatment for critical cardiovascular conditions such as end-stage heart failure and cardiogenic shock. Through the implantation of a mechanical circulatory assist system, part of the patient's heart's pumping function is replaced by a mechanical circulatory assist device, allowing the heart to effectively rest and facilitating functional recovery of the patient's failing heart. It can also be used in percutaneous high-risk coronary interventions and acute heart failure. Mechanical circulatory assist devices include intra-aortic balloon pumps, extracorporeal membrane oxygenation, implantable left ventricular assist devices, and interventional catheter pumps. Compared to other mechanical circulatory assist devices, interventional catheter pumps are less invasive and easier to implant. However, the advantage of their small size is directly contradictory to their pumping performance. Reducing the size and space required for intervention and intravascular delivery while providing adequate blood supply replacement is key to improving treatment efficacy, improving patient prognosis, and expanding the product's applicable population.

[0003] The size of the interventional wound is directly related to the size of the vascular interventional sheath. The expandable vascular interventional sheath (expandable sheath) has a smaller inner diameter (such as 9Fr) during percutaneous intervention in human blood vessels. When an interventional device needs to pass through, its inner diameter expands with the size of the interventional device (such as expanding to 20Fr), and then completely returns to its original size (such as 9Fr) after the device passes through. The size of the expandable sheath only expands briefly when the interventional device passes through, so it is beneficial to reduce the size of the interventional wound. Generally speaking, the greater the expansion ratio of the expandable sheath (the ratio of the size before expansion to the size after expansion), the more conducive it is to reducing the size of the interventional wound, but the less conducive it is to reducing the size of the delivery (withdrawal) force when the device passes through; especially for a disposable expandable sheath containing a metal support structure, the size of the delivery (withdrawal) force will greatly affect the difficulty of delivering (withdrawing) the interventional device, and even affect the success or failure of the device intervention.

[0004] Therefore, there is a need to improve the expandable sheath and its supporting structure to reduce the difficulty of passing the interventional device through the expandable sheath. Summary of the Invention

[0005] The purpose of the present application is to provide an expandable sheath and its supporting structure, which can reduce the delivery (withdrawal) force of the device and reduce the difficulty of the device passing through the expandable sheath.

[0006] The technical solutions provided by the present invention are as follows:

[0007] A support structure for an expandable sheath, comprising:

[0008] The bracket comprises a main body portion and a connecting portion;

[0009] The main body is cylindrical and is configured to expand radially under the action of an external force and contract radially after the external force is removed. The main body includes a fixing rib extending in the axial direction to limit the axial length of the main body.

[0010] The connecting portion is provided at the proximal end of the fixing rib and is used for docking with the external component, and a limiting structure is provided between the connecting portion and the external component;

[0011] When an external instrument penetrates into or withdraws from the stent, a part of the main body is forced to move axially, and the other part is axially limited by the limiting structure.

[0012] In some embodiments, the main body further comprises a plurality of annular frames, and the plurality of annular frames are sequentially arranged along an axis and fixedly connected via fixing ribs;

[0013] The annular skeleton includes a plurality of deformation units connected end to end. The deformation units are configured to expand radially under the action of an external force and contract radially after the external force is removed.

[0014] In some embodiments, the fixing rib includes a first fixing rib disposed between two adjacent deformation units;

[0015] The connecting portion includes a first connecting rod, which is provided at the proximal end of the first fixing rib;

[0016] The limiting structure includes a limiting member, which is arranged at the proximal end of the first connecting rod, and the size of the limiting member in the circumferential direction of the main body is larger than the size of the first connecting rod in the circumferential direction of the main body.

[0017] In some embodiments, the deformation unit includes two connected deformation arms, and ends of the two deformation arms that are away from each other extend toward the proximal end or the distal end and are respectively connected to the first fixing ribs on both sides of the deformation unit.

[0018] In some embodiments, the fixing rib includes a second fixing rib disposed between two deformable arms of the deformable unit;

[0019] The connecting portion includes a second connecting rod, which is arranged at the proximal end of the second fixing rib.

[0020] In some embodiments, the ends of the two deformable arms of the deformable unit that are away from each other both extend toward the distal end;

[0021] The external component is a sheath head, and the limiting structure further includes a first limiting groove and a second limiting groove, and the first limiting groove and the second limiting groove are both opened at the distal end of the sheath head;

[0022] The first groove is used to accommodate the proximal end of the first connecting rod and the limiting member, and a movable space for axial movement of the limiting member is formed in the first groove, and the distal end of the movable space has a first limiting surface; the second limiting groove is used to accommodate the proximal end of the second connecting rod, and the second connecting rod can move axially relative to the second limiting groove, and the proximal end of the second limiting groove has a second limiting surface;

[0023] When the external instrument penetrates from the proximal end of the bracket and drives the main body to expand under force, the first limiting surface limits the limiting member from moving toward the distal end, and the second connecting rod moves toward the distal end relative to the second limiting groove; when the external instrument penetrates from the proximal end of the bracket and the main body contracts, the second limiting surface limits the second connecting rod from moving toward the proximal end, and the limiting member moves toward the proximal end relative to the first limiting groove.

[0024] In some embodiments, the first limiting groove includes a first groove body and a second groove body;

[0025] The first groove body is used to accommodate the proximal end of the first connecting rod, and the second groove body is connected to the proximal end of the first groove body and is used to accommodate the limiting member;

[0026] The axial dimension of the second groove body is larger than the axial dimension of the limiting member, and is used to provide a movable space for the limiting member. In addition, a step structure is formed at the connection between the first groove body and the second groove body, and the proximal end of the step structure forms a first limiting surface.

[0027] In some embodiments, the axial dimension of the first groove body is 3-5 times the axial dimension of the deformation unit, and the difference between the axial dimension of the second groove body and the axial dimension of the limiter is 3-5 times the axial dimension of the deformation unit;

[0028] and / or

[0029] The axial dimension of the second limiting groove is 3-5 times the axial dimension of the deformation unit;

[0030] and / or

[0031] The circumferential size of the second connecting rod is 1-3 times the circumferential size of the first connecting rod, and the circumferential size of the limiting member is not less than 2 times the circumferential size of the first connecting rod.

[0032] In some embodiments, the deformable arm includes a first deformable segment and a second deformable segment;

[0033] The distal end of the first deformable segment is connected to the proximal end of the second deformable segment, and the proximal end of the first deformable segment is connected to the second fixing rib, and the distal end of the second deformable segment is connected to the first fixing rib; the first deformable segment and the second deformable segment are both arc-shaped and tangent, and the concave surface of the first deformable segment is set toward the distal end, and the concave surface of the second deformable segment is set toward the proximal end.

[0034] The present application also provides an expandable sheath, comprising:

[0035] A sheath tube and an expandable sheath support structure provided on the sheath tube, wherein the expandable sheath support structure is the expandable sheath support structure provided in any of the above embodiments;

[0036] The sheath has a sheath head, and the connecting part is installed at the distal end of the sheath head; the sheath is suitable for external instruments to pass through, and when the external instruments penetrate the main body, the main body expands radially under the external force of the external instruments.

[0037] The technical effects of this application are:

[0038] 1. In the present application, a portion of the main body can be axially limited by providing a connecting portion, so that it remains stationary relative to the operator during the delivery (withdrawal) process, and the remaining portion can move axially under the action of the delivery (withdrawal) force. In addition, during the delivery (withdrawal) process, the inner surface of the stent coating will be subjected to a corresponding friction stress along the axial direction. Combined with the expandable structure of the main body, the friction stress can cause the main body to have an expansion tendency during delivery and / or withdrawal, thereby reducing the resistance of the device during delivery (withdrawal), and then reducing the delivery (withdrawal) force of the device under the same mechanism, reducing the difficulty of the device passing through the expandable sheath.

[0039] 2. In the present application, a first fixing rib is provided between two adjacent deformation units of the stent, and a first connecting rod is provided at the proximal end of the first fixing rib to achieve axial limitation of the first fixing rib. When the ends of the two deformation arms of the deformation unit that are away from each other extend toward the distal end, then, when the instrument penetrates the interior of the stent, the inner surface of the stent coating will be subjected to a friction stress axially pointing toward the distal end. Since the first fixing rib is axially limited, the proximal ends of the two deformation arms will be more inclined to open when subjected to the friction stress, making the main body easier to be stretched during transportation, thereby reducing the transportation force of the instrument. Conversely, when the ends of the two deformation arms of the deformation unit that are away from each other extend toward the proximal end, then when the instrument is withdrawn from the interior of the stent, the main body will also tend to be stretched, reducing the withdrawal force of the instrument.

[0040] 3. In the present application, a second fixing rib is provided between the two deformable arms, and a second connecting rod is provided at the proximal end of the second fixing rib to realize axial limitation of the second fixing rib, in conjunction with the originally provided first connecting rod, and the first limiting surface and the second limiting surface provided on the sheath head corresponding to the first connecting rod and the second connecting rod, when the instrument penetrates into or withdraws from the interior of the bracket, the main body can be correspondingly inclined to expand, thereby reducing the resistance during the delivery (withdrawal) of the instrument and reducing the difficulty of the instrument passing through the expandable sheath. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0042] Figure 1 This is a schematic structural diagram of an expandable sheath support structure provided in one embodiment of the present application;

[0043] Figure 2 This is a schematic diagram of the assembly of a sheath head and an expandable sheath support structure provided in one embodiment of the present application;

[0044] Figure 3 yes Figure 2 A local enlarged schematic diagram of point A shown;

[0045] Figure 4 yes Figure 2 A structural diagram of the support structure for the expandable sheath shown;

[0046] Figure 5 Schematic diagram of the structural deformation of a support structure for an expandable sheath during device delivery (withdrawal) provided in one embodiment of the present application;

[0047] Figure 6 This is a schematic diagram of the design of a support structure for an expandable sheath provided in one embodiment of the present application;

[0048] Figure 7 yes Figure 6 A partial enlarged schematic diagram of point B is shown;

[0049] Figure 8 yes Figure 6 Schematic diagram of deformation of the deformation arm at B shown;

[0050] Figure 9 This is a schematic diagram of the design of a support structure for an expandable sheath provided in another embodiment of the present application;

[0051] Figure 10 This is a schematic design diagram of a support structure for an expandable sheath provided in another embodiment of the present application.

[0052] Description of Figure Numbers:

[0053] 1. Bracket;

[0054] 100, main body; 110, deformation unit; 111, deformation arm; 1111, first deformation section; 1112, second deformation section; 120, first fixing rib; 130, second fixing rib;

[0055] 200, connecting portion; 210, first connecting rod; 211, limiting member; 220, second connecting rod;

[0056] 300, sheath head; 310, first limiting groove; 311, first groove body; 312, second groove body; 313, movable space; 314, first limiting surface; 320, second limiting groove; 321, second limiting surface;

[0057] 400. Equipment. DETAILED DESCRIPTION

[0058] In the following description, specific details such as specific system structures and technologies are provided for illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obstructing the description of the present application with unnecessary details.

[0059] In order to more clearly illustrate the embodiments of this application or the technical solutions in the prior art, the specific implementation methods of this application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without inventive work.

[0060] To simplify the drawings, only the parts relevant to this application are schematically shown in each figure. They do not represent the actual structure of the product. In addition, to simplify the drawings and facilitate understanding, in some figures, only one of the components with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one."

[0061] It should be further understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0062] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this application.

[0063] In the embodiments shown in the accompanying drawings, directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of various components of the present application are not absolute but relative. These descriptions are applicable when these components are in the positions shown in the accompanying drawings. If the descriptions of the positions of these components are changed, these directional indications will also change accordingly.

[0064] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0065] In the embodiments of the present application, "proximal end" refers to the end of the associated object closest to the operator; "distal end" refers to the end of the associated object farther from the operator. "Proximal end" and "distal end" refer to the position or orientation of the associated object (e.g., a component of a medical device) relative to the operator (e.g., a doctor) using the device (e.g., a medical device) on which the associated object resides. For example, "proximal end" refers to the end closest to the doctor during normal operation of the medical device, while "distal end" refers to the end farther from the doctor during normal operation, i.e., the end that first enters the patient's body.

[0066] In order to reduce the size of the interventional wound while reducing the difficulty of the instrument passing through the expandable sheath, the present application provides a support structure for the expandable sheath, which includes an expandable stent. When the instrument enters or exits the stent, a part of the stent is axially limited, and the other part can move axially and assist in the expansion of the stent under the friction of the instrument and the stent coating, thereby reducing the delivery (withdrawal) force of the instrument and reducing the difficulty of the instrument passing through the expandable sheath.

[0067] The following is a description with reference to the accompanying drawings:

[0068] Please refer to Figure 1 、 Figure 4 、 Figure 5 and Figure 10 , which is a support structure for an expandable sheath provided in an embodiment of the present application, including a stent 1, the stent 1 having a main body 100 and a connecting portion 200, wherein the main body 100 is cylindrical in structure and is configured to expand radially under the action of an external force and to contract radially after the external force is removed. The main body 100 also includes a fixing rib extending in the axial direction, which is used to limit the axial length of the main body 100. The connecting portion 200 is provided at the proximal end of the fixing rib and is used to dock with an external component, and the size and shape of the connecting portion 200 can be finalized according to the shape of the external component, so as to achieve circumferential positioning of the entire expandable sheath support structure while also achieving connection transition. The connecting portion 200 can deform in the radial direction in response to the intervention of an external instrument 400, and a limiting structure is provided between the connecting portion 200 and the external component.

[0069] When the external instrument 400 penetrates into or withdraws from the stent 1, a portion of the main body 100 is forced to move axially. At this time, the inner surface of the stent 1 coating (not shown, but the coating is fully integrated with the stent 1 and does not produce relative movement) will be subjected to an axial friction stress. For example, when the instrument 400 penetrates the stent 1 from the proximal end, the friction stress is axially directed to the distal end. This part of the friction stress is generated by the delivery force; another part of the stent 1 is axially limited by the limiting structure and remains stationary relative to the operator. When the delivery force is constant, the above mechanism can convert part of the delivery force to offset the internal stress of the stent 1 material generated when the main body 100 is stretched and deformed, thereby reducing the delivery force of the instrument 400 and reducing the difficulty of the instrument 400 passing through the expandable sheath.

[0070] Specifically, the main body 100 also includes several annular skeletons, preferably made of a superelastic material such as nickel-titanium alloy, with a Young's modulus of 10 to 100 GPa and an elastic strain range greater than 1%. The annular skeletons are arranged sequentially along an axis and fixedly connected by fixing ribs. The annular skeletons include several deformable units 110 connected end to end. The deformable units 110 are configured to expand radially under external force and contract radially after the external force is removed, thereby achieving radial expansion and contraction of the main body 100.

[0071] In one example embodiment, see Figure 5 and Figure 10 The fixing ribs include a first fixing rib 120, which is disposed between two adjacent deformation units 110. The connecting portion 200 includes a first connecting rod 210, which is disposed proximal to the first fixing rib 120. The limiting structure includes a limiting member 211, which is disposed proximal to the first connecting rod 210. In this case, the deformation unit 110 may specifically include two connected deformation arms 111, wherein the ends of the two deformation arms 111 that are away from each other extend toward the distal end and are respectively connected to the first fixing ribs 120 on both sides of the deformation unit 110.

[0072] By means of the stopper 211 and the first connecting rod 210, the first fixing rib 120 and the ends of the deformable arm 111 connected thereto are axially limited, while the portion of the deformable arm 111 other than the two ends can still move axially. When the instrument 400 is delivered (penetrating from the proximal end into the interior of the stent 1), the inner surface of the stent 1 coating is subjected to a frictional stress directed axially toward the distal end. Because the first connecting rod 210 is axially limited, the first fixing rib 120 and the ends of the deformable arm 111 connected thereto remain stationary relative to the operator; while the portion of the deformable arm 111 other than the two ends is pushed toward the distal end along with the coating under the influence of the frictional stress, causing the stent 1 main body 100 to tend to expand. This reduces the resistance during delivery of the instrument 400, thereby reducing the delivery force of the instrument 400 under the same mechanism, reducing the difficulty of the instrument 400 passing through the expandable sheath. Conversely, under the same delivery force, a larger instrument 400 can pass through.

[0073] However, when the device 400 is withdrawn (from the stent 1 proximally), the inner surface of the stent coating is subjected to a frictional stress directed axially toward the proximal end. Driven by this frictional stress, the portion of the deformable arm 111 other than the two ends is connected to the coating and pushed proximally, causing the main body 100 to contract, thereby generating a side effect of increased withdrawal force. For example, when the friction coefficient between the coating and the device 400 is 0.1-0.2, the withdrawal force is approximately 20% greater than the delivery force. In one embodiment, the maximum deformation shape of the deformable arm 111 tends to be a monotonic function curve (e.g., a straight line) so that when the device 400 passes, the deformable arm 111 can always maintain a tendency to move toward the distal end and toward an increasing circumferential dimension. Specifically, the deformable arm 111 includes a first deformable segment 1111 and a second deformable segment 1112. The proximal ends of the first deformable segments 1111 of the two deformable arms 111 corresponding to each deformable unit 110 are connected, the distal ends of the first deformable segments 1111 are respectively connected to the proximal ends of the second deformable segments 1112, and the distal ends of the second deformable segments 1112 are respectively connected to the first fixing ribs 120 on both sides of the deformable unit 110. The first deformable segment 1111 and the second deformable segment 1112 are both arc-shaped and tangent to each other, with the concave surface of the first deformable segment 1111 facing the distal end, and the concave surface of the second deformable segment 1112 facing the proximal end. On the one hand, when the main body 100 is expanded to its maximum size, the tangent direction of the curve at the intersection of the first deformation segment 1111 and the second deformation segment 1112 remains parallel to the axial direction, thereby reducing the adverse effect on the withdrawal force; on the other hand, the arc-shaped structure is more conducive to the deformation unit 110 obtaining a larger deformation length within a limited plane space.

[0074] In contrast, if the ends of the two deformable arms 111 of the deformable unit 110 that are away from each other both extend toward the proximal end (not shown), the withdrawal force of the instrument 400 can be reduced with the help of the limiter 211 and the first connecting rod 210, but it will also have an adverse effect on the delivery force. In this regard, the deformable arm 111 structure proposed in the above embodiment (the maximum deformation shape of the deformable arm 111 tends to be a monotonic function curve) can be used for improvement. No further details will be given here, as they are all within the scope of protection of this application.

[0075] The main body 100 in the above embodiments is only provided with the first fixing rib 120, which has a simple structure and is easy to manufacture. Figure 5 and Figure 9In some specific embodiments, to further enhance the structural stability of the stent 1, the fixing ribs may further include a second fixing rib 130 disposed between the two deformable arms 111 of the deformable unit 110. The second fixing rib 130 is not axially constrained, and therefore does not affect the deformation of the deformable arms 111 during delivery (or withdrawal) of the device 400. The distal ends of the first fixing rib 120 and the distal ends of the second fixing rib 130 are both connected to the proximal end wall of the distalmost annular framework.

[0076] In one exemplary embodiment, the connecting portion 200 further includes a second connecting rod 220, which is disposed proximal to the second fixing rib 130. In this case, the second connecting rod 220 can be circumferentially limited to the outer components of the expandable sheath by means of opening a hole or other methods, thereby improving the operator's control over the entire expandable sheath.

[0077] Specifically, see Figures 2 to 8 Taking the example of a deformable unit 110 in which the two deformable arms 111 extend distally at their ends, the external component is the sheath head 300. This, combined with the stent 1 covering structure (not shown), forms a continuous cavity, facilitating operator control of the expandable sheath for guidance and intervention. A sealing structure (not shown) is provided to prevent blood leakage after the device 400 is inserted. The limiting structure also includes a first limiting groove 310 and a second limiting groove 320, both of which are located at the distal end of the sheath head 300. The first groove 311 is used to accommodate the proximal end of the first connecting rod 210 and the stopper 211. A movable space 313 is formed within the first groove 311, allowing the stopper 211 to move axially. The stopper 211 is larger in size around the main body 100 than the first connecting rod 210. The distal end of the movable space 313 has a first stopper surface 314, which abuts against the distal end of the stopper 211, thereby limiting the movement of the stopper 211. The second stopper groove 320 is used to accommodate the proximal end of the second connecting rod 220. The second connecting rod 220 is axially movable relative to the second stopper groove 320. The proximal end of the second stopper groove 320 has a second stopper surface 321. In this way, when the instrument 400 is transported (the instrument 400 penetrates from the proximal end of the bracket 1 and drives the main body 100 to expand under force), the first limiting surface 314 can limit the limiting member 211 and the first connecting rod 210 from moving toward the distal end, and the second connecting rod 220 can move toward the distal end relative to the second limiting groove 320; conversely, when the instrument 400 is withdrawn (the instrument 400 penetrates from the proximal end of the bracket 1 and the main body 100 contracts), the second limiting surface 321 can limit the second connecting rod 220 from moving toward the proximal end, and the limiting member 211 and the first connecting rod 210 can move toward the proximal end relative to the first limiting groove 310.

[0078] In this embodiment, the distal end of the first deformable segment 1111 of the deformable arm 111 is connected to the proximal end of the second deformable segment 1112. The proximal end of the first deformable segment 1111 is connected to the second fixing rib 130, and the distal end of the second deformable segment 1112 is connected to the first fixing rib 120. The first deformable segment 1111 and the second deformable segment 1112 are both arc-shaped and tangential to each other. The concave surface of the first deformable segment 1111 is disposed toward the distal end, while the concave surface of the second deformable segment 1112 is disposed toward the proximal end.

[0079] During delivery of the device 400, the main body 100 tends to move distally, but the first fixing rib 120 and the first connecting rod 210 are axially limited by the limiting member 211 and the first limiting surface 314, while the second fixing rib 130 is still free to move axially. The stent 1 coating can drive the second fixing rib 130 and the deformable arm 111 to move distally under the action of frictional stress, thereby reducing the delivery force of the device 400. During withdrawal of the device 400, the main body 100 tends to move proximally, but the second fixing rib 130 is axially limited because the proximal surface of the second connecting rod 220 is limited by the second limiting surface 321. However, the first fixing rib 120 is still free to move axially proximally. The stent 1 coating drives the first fixing rib 120 and the deformable arm 111 to move proximally under the action of frictional stress, thereby reducing the withdrawal force of the device 400. In this embodiment, the device 400 can reduce resistance by about 10% during delivery (withdrawal), greatly reducing the difficulty of the device 400 passing through the expandable sheath, and facilitating operation for the operator.

[0080] Specifically, see Figure 2 and Figure 3 The first limiting groove 310 includes a first groove body 311 and a second groove body 312. The first groove body 311 is used to accommodate the proximal end of the first connecting rod 210. The second groove body 312 is connected to the proximal end of the first groove body 311 and is used to accommodate the limiting member 211. The axial dimension of the second groove body 312 is larger than the axial dimension of the limiting member 211, and is used to provide a movable space 313 for the limiting member 211. In addition, a step structure is formed at the connection between the first groove body 311 and the second groove body 312, and the proximal end of the step structure forms the above-mentioned first limiting surface 314.

[0081] See also Figure 3 、 Figure 6 and Figure 7The main body of the first connecting rod 210 is a long rod with a width of T1, and the limiting member 211 at its proximal end is a protrusion, the circumferential dimension of the protrusion is a, and the axial dimension is b. In this embodiment, the shape of the limiting member 211 is preferably a circle with a diameter of R1 (after the plane is unfolded), so a=b=R1. Among them, a≥2×T1 (that is, R1≥2×T1) so that an effective limit can be formed. The second connecting rod 220 is a long rod with a width of T2. Since the second connecting rod 220 will be under pressure when the instrument 400 is withdrawn, in order to prevent instability, T2=(1~3)×T1, but to simplify the design, T1=T2.

[0082] The second limiting groove 320 is a rectangular hollow structure. During transport of the instrument 400, the maximum distal movement distance of the second connecting rod 220 is L (the maximum axial deformation length of the deformable arm 111). To prevent it from dislodging from the second limiting groove 320, the axial dimension of the second limiting groove 320 is L3 = (3-5) × L; its circumferential dimension is slightly wider than T2. ​​Conversely, the bearing dimension of the first groove body 311 of the first limiting groove 310 is L2 = L3 = (3-5) × L, and its circumferential dimension is slightly wider than T1, but less than a(R1). The second groove body 312 of the first limiting groove 310 is also a rectangular cavity structure. During the withdrawal of the instrument 400, the maximum distance that the second connecting rod 220 moves toward the proximal end is L. In order to ensure that its axial movement is not interfered with, the axial dimension of the second groove body 312 is L2 = b + (3~5) × L, and its circumferential dimension is slightly larger than a (a=b=R1).

[0083] Furthermore, the maximum axial deformation length of the deformable arm 111 is the length of the deformable unit 110, L = (0.5-1.5) × OD, where OD is the outer diameter of the main body 100 and the width of the deformable unit 110 is 2W = (π × OD) / n, where n is the number of times the deformable unit 110 is repeated circumferentially around the stent 1. If n is greater than or equal to 2, the structure will not hold. A larger n provides better support for the stent 1, but this also increases the delivery (withdrawal) force of the device 400 and the design difficulty. Therefore, a value of 3 for n is a preferred value for practical design and is also the value used in the embodiments of this application. The widths of the first fixing rib 120 and the second fixing rib 130 are T3 and T4, respectively. To simplify the design, T3 = T4 = (0.01-0.08) × OD can be selected. T3 and T4 should be as small as possible to provide more design space for the deformable arm 111. However, T3 and T4 should not be too small, otherwise the first fixing rib 120 and the second fixing rib 130 will easily become unstable and bend during the withdrawal of the instrument 400. The deformable arm 111 is composed of two tangent arcs (a first deformable segment 1111 and a second deformable segment 1112), with radii R2 and R3, respectively. To simplify the design, R2 = R3 = (0.5-1.5) × OD / n can be selected. The larger the R2 and R3, the greater the maximum deformation length of the deformable arm 111, the smaller the delivery (withdrawal) force of the instrument 400, but the support of the stent 1 will be reduced.

[0084] See also Figure 2 and Figure 5 The present application also provides an expandable sheath, comprising a sheath tube and an expandable sheath support structure disposed on the sheath tube, wherein the expandable sheath support structure is the expandable sheath support structure provided in any of the above-described embodiments. The sheath tube comprises a sheath head 300, with a connector 200 mounted at the distal end of the sheath head 300. The sheath tube is adapted to receive an external instrument 400 therethrough. When the external instrument 400 is inserted into the main body 100, the main body 100 expands radially due to the external force exerted by the external instrument 400. When the device 400 is delivered (withdrawn), part of the main body 100 is axially limited, so that it remains stationary relative to the operator during the delivery (withdrawal) process, and the remaining part can move axially under the action of the delivery (withdrawal) force. During the delivery (withdrawal) process, the inner surface of the stent 1 coating will be subjected to a corresponding axial friction stress. Combined with the expandable structure of the main body 100, the friction stress can cause the main body 100 to have an expansion trend during delivery and / or withdrawal, thereby reducing the resistance of the device 400 during delivery (withdrawal), and then reducing the delivery (withdrawal) force of the device 400 under the same mechanism, reducing the difficulty of the device 400 passing through the expandable sheath.

[0085] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0086] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of this application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications should also be considered as the scope of protection of this application.

Claims

1. A support structure for an expandable sheath, characterized in that: include: The bracket comprises a main body portion and a connecting portion; The main body is cylindrical and is configured to expand radially under the action of an external force and contract radially after the external force is removed, and the main body includes a fixing rib extending in the axial direction to limit the axial length of the main body; The connecting portion is provided at the proximal end of the fixing rib and is used for docking with the external component, and a limiting structure is provided between the connecting portion and the external component; When an external instrument penetrates into or withdraws from the bracket, a part of the main body is forced to move axially, and the other part is axially limited by the limiting structure.

2. The expandable sheath support structure according to claim 1, characterized in that: The main body also includes a plurality of annular frames, and the plurality of annular frames are arranged in sequence along an axis and fixedly connected by the fixing ribs; The annular skeleton includes a plurality of deformation units connected end to end, and the deformation units are configured to expand radially under the action of an external force and contract radially after the external force is removed.

3. The support structure for expandable sheath according to claim 2, characterized in that: The fixing ribs include a first fixing rib, which is provided between two adjacent deformation units; The connecting portion includes a first connecting rod provided at the proximal end of the first fixing rib; The limiting structure includes a limiting member, which is provided at the proximal end of the first connecting rod, and a size of the limiting member in the circumferential direction of the main body is larger than a size of the first connecting rod in the circumferential direction of the main body.

4. The expandable sheath support structure according to claim 3, wherein: The deformation unit includes two connected deformation arms, and ends of the two deformation arms that are away from each other extend toward the proximal end or the distal end and are respectively connected to the first fixing ribs on both sides of the deformation unit.

5. The expandable sheath support structure according to claim 4, characterized in that: The fixing rib includes a second fixing rib, which is provided between the two deformable arms of the deformable unit; The connecting portion includes a second connecting rod, which is arranged at the proximal end of the second fixing rib.

6. The support structure for expandable sheath according to claim 5, characterized in that: One end of the two deformable arms of the deformable unit, which are away from each other, both extend toward the distal end; The external component is a sheath head, and the limiting structure further includes a first limiting groove and a second limiting groove, and the first limiting groove and the second limiting groove are both opened at the distal end of the sheath head; The first groove is used to accommodate the proximal end of the first connecting rod and the limiting member, and a movable space for axial movement of the limiting member is formed in the first groove, and the distal end of the movable space has a first limiting surface; the second limiting groove is used to accommodate the proximal end of the second connecting rod, and the second connecting rod can move axially relative to the second limiting groove, and the proximal end of the second limiting groove has a second limiting surface; When an external instrument penetrates from the proximal end of the bracket and drives the main body to expand under force, the first limiting surface limits the movement of the limiting member toward the distal end, and the second connecting rod moves toward the distal end relative to the second limiting groove; when the external instrument penetrates from the proximal end of the bracket and the main body contracts, the second limiting surface limits the movement of the second connecting rod toward the proximal end, and the limiting member moves toward the proximal end relative to the first limiting groove.

7. The support structure for expandable sheath according to claim 6, characterized in that: The first limiting groove includes a first groove body and a second groove body; The first groove body is used to accommodate the proximal end of the first connecting rod, and the second groove body is connected to the proximal end of the first groove body and is used to accommodate the limiting member; The axial dimension of the second groove body is greater than the axial dimension of the limiting member, and is used to provide the movable space for the limiting member. In addition, a step structure is formed at the connection between the first groove body and the second groove body, and the proximal end of the step structure forms the first limiting surface.

8. The support structure for expandable sheath according to claim 7, characterized in that: The axial dimension of the first groove body is 3-5 times the axial dimension of the deformation unit, and the difference between the axial dimension of the second groove body and the axial dimension of the limiting member is 3-5 times the axial dimension of the deformation unit; and / or The axial dimension of the second limiting groove is 3-5 times the axial dimension of the deformation unit; and / or The circumferential size of the second connecting rod is 1-3 times the circumferential size of the first connecting rod, and the circumferential size of the limiting member is not less than 2 times the circumferential size of the first connecting rod.

9. The support structure for expandable sheath according to any one of claims 5 to 8, characterized in that: The deformable arm includes a first deformable segment and a second deformable segment; The distal end of the first deformable segment is connected to the proximal end of the second deformable segment, and the proximal end of the first deformable segment is connected to the second fixing rib, and the distal end of the second deformable segment is connected to the first fixing rib; the first deformable segment and the second deformable segment are both arc-shaped and tangent, and the concave surface of the first deformable segment is set toward the distal end, and the concave surface of the second deformable segment is set toward the proximal end.

10. An expandable sheath, characterized in that: include: A sheath tube and an expandable sheath support structure provided on the sheath tube, wherein the expandable sheath support structure is the expandable sheath support structure according to any one of claims 1 to 9; The sheath tube has a sheath head, and the connecting part is installed at the distal end of the sheath head; the sheath tube is suitable for allowing external instruments to pass through, and when the external instrument penetrates the main body, the main body expands radially under the external force of the external instrument.

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