Reverse microcatheter for interventional therapy

Abstract

The invention discloses a reverse micro-catheter for interventional therapy, which comprises a catheter main body provided with a through consumable channel for an interventional consumable to pass through, a plurality of restraining cavities are arranged in the catheter wall of the catheter main body along the axial direction parallel to the catheter main body, and the restraining cavities are distributed along the circumferential direction of the catheter main body; at least part of the elastic piece is located in the restraining cavity and is in sliding connection with the restraining cavity, and the far end of the elastic piece has an initial state restrained by the restraining cavity and an expansion state in which the elastic piece is separated from restraining and expands under the action of self elasticity; the elastic sleeve is arranged at the far end of the catheter body, the far end of the elastic piece is configured to extend into the elastic sleeve in an operable mode, and in the expansion state, the elastic piece stretches the elastic sleeve and enables the elastic sleeve to expand outwards. According to the microcatheter, a stable axial guide channel can be formed, the forward guide wire can be conveniently led into the reverse microcatheter, the inner space of the catheter body is released to the maximum extent through the restraining cavity formed in the catheter wall, and the effective diameter of the consumable channel is remarkably increased.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and more specifically, to a retrograde microcatheter for interventional therapy. Background Technology

[0002] In CTO interventional treatment, cases of chronic total coronary artery occlusion (CTCO) are frequently encountered. In these cases, the proximal fibrous cap of the lesion often becomes abnormally hard due to long-term fibrosis and calcification, making it difficult for the antegrade guidewire (especially a rigid guidewire) to penetrate or causing it to easily deviate from the true lumen, thus hindering the passage of the occluded segment. Conversely, because the distal fibrous cap of the occluded segment is usually thinner or more loosely structured, the guidewire can penetrate more easily into the true lumen. Therefore, the operator often chooses to utilize good collateral circulation and initiate the retrograde guidewire technique to establish access. The retrograde guidewire technique involves the retrograde microcatheter and the retrograde guidewire advancing synchronously through the occluded segment. The retrograde guidewire first enters the antegrade extension catheter, and then, along the retrograde guidewire, the retrograde microcatheter enters the extension catheter to form access. The antegrade guidewire is then advanced, and after passing through the occluded segment, the retrograde microcatheter and retrograde microguidewire are withdrawn. The antegrade extension catheter is then guided through the occluded segment along the antegrade guidewire to achieve access. When inserting a positron into a retrograde microcatheter, the operator often needs to spend a lot of time getting the positron into the retrograde microcatheter. Summary of the Invention

[0003] The main objective of this application is to provide a retrograde microcatheter for interventional treatment, in order to solve the problem that when a antegrade guidewire is inserted into a retrograde microcatheter in related technologies, the operator often needs to spend a lot of time to insert the antegrade guidewire into the retrograde microcatheter.

[0004] To achieve the above objectives, this application provides a retrograde microcatheter for interventional therapy, comprising: The catheter body has a through consumable channel for interventional consumables to pass through. A constraint cavity is provided inside the wall of the catheter body. The constraint cavity is arranged along the axial direction parallel to the catheter body, and multiple constraint cavities are provided and distributed along the circumference of the catheter body. An elastic element is at least partially located within and slidably connected to the constraint cavity. The distal end of the elastic element has an initial state constrained by the constraint cavity and an expanded state in which it is freed from the constraint and expands under its own elastic force. An elastic sleeve is located at the distal end of the catheter body. The distal end of the elastic element is configured to extend operably into the elastic sleeve. In the expanded state, the elastic element stretches the elastic sleeve and causes the elastic sleeve to expand outward.

[0005] With the above settings, on the one hand, when the elastic element is removed from the constraint cavity by the operation, its distal end enters an expansion state under its own elastic force, thereby stretching the elastic sleeve fitted on the distal end of the catheter body, so that the elastic sleeve expands radially outward and tightly abuts against the inner wall of the antegrade catheter, forming a stable axial guide channel. This limits the travel path of the antegrade guidewire to the coaxial range between the elastic sleeve and the consumable channel of the catheter body, effectively avoiding the problem of guidewire deviation, jamming or mis-entry into branches in complex vascular environments (such as tortuous vessels, branch vessels or proximal occlusion lesions). It significantly reduces the difficulty of the antegrade guidewire entering the consumable channel of the catheter body, and improves the accuracy and efficiency of guidewire puncture, especially suitable for complex coronary artery surgery scenarios such as CTO intervention. On the other hand, by using the built-in constraint cavity in the tube wall, the expansion process only requires pushing the elastic element to slide along the constraint cavity to trigger the expansion of the elastic sleeve. There is no need to configure the movable sleeve used to constrain / release the elastic element in the traditional design, thereby maximizing the release of the internal space of the conduit body and significantly increasing the effective diameter of the consumable channel.

[0006] Optionally, the elastic element is configured to have two or more expansion states, in which the elastic sleeve has different maximum outer diameters.

[0007] With the above settings, the elastic element can drive the elastic sleeve to stretch and expand to different maximum outer diameters under different expansion states, which can accurately adapt to the needs of different catheter diameters in interventional surgery, maintain the stability of the constructed guide channel, and avoid the elastic sleeve support from loosening due to changes in catheter diameter.

[0008] Optionally, the elastic element includes a stabilizing segment and an expanding segment, with the expanding segment connected to the distal end of the stabilizing segment. In the initial state, the stabilizing segment and the expanding segment are located within the constraint cavity, and the expanding segment is constrained by the constraint cavity. In the expanding state, at least a portion of the expanding segment extends beyond the distal end of the constraint segment and expands under its own elastic force. In different expanding states, the length by which the expanding segment extends beyond the distal end of the constraint segment is different.

[0009] Through the above setup, on the one hand, the stabilizing section always remains within the constraint cavity and slides smoothly connected to it. Its rigid structure provides a fixed motion reference for the expansion section. When the elastic element is pushed, the stabilizing section slides smoothly along the axial direction of the constraint cavity, ensuring that the expansion section extends only along the axis of the catheter body without radial offset or swaying. The expansion section is specifically designed for "elastic expansion after release from constraint," without needing to consider support and guidance. It can use more suitable elastic materials (such as shape memory alloy wire, high-elasticity medical plastic) and structures, making the expansion force more concentrated and the expansion shape more regular. At the same time, the constraint effect of the stabilizing section prevents the expansion section from expanding prematurely before it is fully extended, ensuring that all the expansion force acts on the stretching of the elastic sleeve, improving the uniformity and reliability of the elastic sleeve's expansion. On the other hand, doctors can precisely control the extension length of the dilation segment by controlling the stroke of the elastic element, thereby controlling the outward expansion of the elastic sleeve and avoiding the uncontrollability of traditional elastic elements that expand completely after being pushed. For example, in a small-diameter catheter, only a small stroke is pushed to slightly extend the dilation segment, and the elastic sleeve expands slightly to fit the inner wall of the blood vessel; in a large-diameter catheter or when large consumables need to be delivered, a larger stroke is pushed to fully extend the dilation segment, and the elastic sleeve expands to the maximum to achieve stable support.

[0010] On the other hand, the expansion state of the elastic element can be precisely controlled by a single operation (such as pushing the elastic element's stroke). The operation logic is simple and intuitive, and doctors do not need to learn complicated instrument control methods to quickly master the outer diameter adjustment skills. On the other hand, the supporting effect of the stabilizing segment makes the expansion of the elastic sleeve more uniform, further improving the coaxiality of the guide channel. Combined with the expanded consumable channel, it makes the advancement of large-diameter interventional consumables smoother. The variable extension length brings precise expansion adjustment, which allows the elastic element to adapt to blood vessels of different diameters and to be dynamically adjusted throughout the entire surgical procedure. This avoids surgical interruptions caused by changing instruments. Together with the "no movable cannula required" design, it simplifies the instrument structure and improves surgical efficiency and safety.

[0011] Optionally, the distal end of the elastic element is provided with a return bend, which abuts against the inner wall of the elastic sleeve in the expanded state.

[0012] With the above configuration, on the one hand, the return bend has an arc-shaped or hook-shaped structure, providing a large contact area with the distal inner end face of the elastic sleeve. This provides stable support for the elastic sleeve when passing through the blocking section in reverse and prevents stress concentration that could puncture the elastic sleeve. On the other hand, during the extension of the elastic element, the large contact area between the return bend and the elastic sleeve disperses the expansion pressure of the elastic element to multiple areas of the inner wall of the elastic sleeve, preventing excessive local pressure that could lead to fatigue, tearing, or permanent deformation of the elastic sleeve material. Especially in multi-stage expansion states, even if the elastic sleeve is stretched significantly, the uniform force distribution of the return bend ensures that the elastic sleeve always operates within a safe elastic range.

[0013] On the other hand, in the expanded state, the contact between the bend and the inner wall of the elastic sleeve forms an "internal support skeleton", which allows the elastic sleeve to not only expand outward by its own elasticity, but also resist the compression of the inner wall of the blood vessel or the pushing pressure of interventional consumables through the rigid support of the bend.

[0014] Optionally, the elastic element is a metal wire.

[0015] With the above configuration, on the one hand, the metal wire has both moderate rigidity and elasticity, which can provide sufficient radial expansion force during expansion to push the elastic sleeve to expand evenly outward along the circumference and form a regular circular guide channel; on the other hand, it can avoid excessive rigidity from causing localized force concentration on the elastic sleeve. On the other hand, metal wire has high plasticity and can be precisely bent into arc-shaped, hook-shaped, and other bend structures. Once formed, the shape is stable and will not deform at the bend angle due to expansion or retraction operations. A reliable bend structure can form a stable multi-point contact with the inner wall of the elastic sleeve, dispersing pressure through the contact surface and reducing the risk of damage to the elastic sleeve. On the other hand, the diameter of the metal wire can be precisely controlled. Compared with traditional plastic elastic components, the thinner diameter metal wire occupies less space in the constraint cavity, eliminating the need to reserve too much radial space for the elastic component. This further frees up the internal space of the catheter body. Combined with the design of "internal constraint cavity built into the tube wall and no additional movable sleeve", the effective diameter of the consumable channel is maximized, ensuring the smooth passage of large-diameter interventional consumables. In addition, multiple metal wire elastic components (matching the number of constraint cavities) can be set along the circumference of the catheter body. Each metal wire independently bears part of the expansion force, which can improve the uniformity of elastic sleeve expansion through multi-point support, and will not occupy too much space due to the large diameter of a single metal wire. This achieves a balance between enhanced support force and compact space, meeting the core requirements of small outer diameter and multi-functionality of minimally invasive interventional devices.

[0016] Optionally, the elastic element is a flat metal wire.

[0017] With the above configuration, on the one hand, when the metal flat wire is in the expanded state, there is more contact area between the metal flat wire and the elastic sleeve, so that the expansion force can be evenly distributed to the circumferential direction of the inner wall of the elastic sleeve, avoiding uneven stretching of the elastic sleeve caused by local force concentration, ensuring that the elastic sleeve always forms a regular circular guide channel, reducing friction and jamming when the guide wire and interventional consumables are advanced, especially suitable for the smooth passage of large-diameter consumables; on the other hand, the metal flat wire has a smaller radial thickness, reducing the radial space occupied, which can further reduce the radial size of the constraint cavity, thereby maximizing the release of the internal space of the catheter body; On the other hand, after the elastic element is set as a flat metal wire, its flat cross section makes it less prone to torsion and slippage during axial sliding and radial expansion. When the flat wire in the stable section slides along the axial direction of the constraint cavity, the flat structure has a higher degree of fit with the inner wall of the constraint cavity and the movement trajectory is more accurate, ensuring that the expansion section extends only along the axial direction and does not have the "spiral offset" that is common with round wires. This further ensures the coaxiality of the elastic sleeve and the consumable channel and improves the accuracy of the guide wire guidance. On the other hand, the flat cross-section of metal flat wire is easier to process and shape through precision bending, laser cutting and other processes. In particular, the preset shape of the expansion section and the arc structure of the return bend have a dimensional accuracy that is much higher than that of the round wire. This ensures that the expansion shape and return bend angle of multiple elastic elements are completely consistent, and the tension on the elastic sleeve is uniform and synchronous during expansion, avoiding the tilting or irregular expansion of the elastic sleeve caused by the forming deviation of a single elastic element.

[0018] Optionally, the cross-section of the elastic element in the radial direction of the conduit body is a flat rectangle.

[0019] With the above configuration, the elastic element, having a flat rectangular cross-section, achieves a higher degree of fit with the inner wall of the constraint cavity. Furthermore, its geometric shape effectively restricts the torsional movement of the elastic element within the constraint cavity, improving the accuracy of the motion trajectory and further enhancing the coaxiality of the elastic sleeve and the consumable channel. Moreover, the long side of the flat rectangular cross-section is distributed circumferentially along the conduit body, allowing multiple elastic elements to be closely arranged without requiring excessive circumferential gaps. With the same conduit outer diameter, more elastic elements can be arranged to achieve multi-point support.

[0020] Optionally, the catheter body includes: The inner tube has a through-flow consumable channel through which interventional consumables pass; The outer tube is sleeved and fixed outside the inner tube. The inner wall of the outer tube is provided with multiple mounting cavities distributed circumferentially, and the mounting cavities are arranged parallel to the axial direction of the outer tube. The sheath tube is embedded and fixed inside the installation cavity, and a constraint cavity is provided inside the sheath tube.

[0021] Through the above setup, the inner tube independently undertakes the core function of allowing interventional consumables to pass through. It can be made of low-friction, high-smoothness medical materials (such as PTFE or PEEK), and its inner diameter can be precisely controlled to maximize the smoothness and effective diameter of the consumable channel. The outer tube is sleeved and fixed outside the inner tube, forming a rigid support framework. Multiple installation cavities distributed circumferentially within its inner wall provide a precise installation reference for the sheath. The outer tube can be made of medical tubing with moderate rigidity, ensuring the overall structural strength of the catheter body and preventing bending or deformation under pressure within the blood vessel. Precision machining ensures the uniform circumferential distribution of multiple installation cavities, laying the foundation for the synchronous movement of the elastic element and the uniform expansion of the elastic sleeve. The sheath is embedded and fixed within the installation cavities, and its internal constraint cavity is specifically adapted to the structural shape of the elastic element. This dedicated cavity design avoids direct contact between the elastic element and the inner and outer tubes, concentrating the constraint function within the sheath, ensuring that the sliding and expansion movements of the elastic element always follow a preset trajectory.

[0022] Optionally, it further includes: an operating part connected to the proximal end of the catheter body, the operating part including a fixed end and an operating end, the operating end being configured to be operably movable relative to the fixed end along the axial direction of the catheter body, the proximal end of the elastic element extending out of the catheter body and connected to the operating end, the operating end driving the elastic element to move toward the distal end.

[0023] With the above settings, the operating end moves only along the axial direction of the catheter body, and the driving force is directly converted into the axial advancement of the elastic element. The operation action and the expansion effect of the elastic sleeve form a "linear correspondence". That is, the farther the operating end is pushed, the longer the elastic element extends and the greater the expansion amplitude of the elastic sleeve. There is no need for complex force transmission and conversion. The intuitive operation logic allows doctors to directly predict the expansion effect through the "pushing stroke" and confirm it with intraoperative imaging, reducing the learning and operation difficulty. It is especially suitable for interventional scenarios with limited surgical field and narrow operating space.

[0024] Optionally, the fixed end includes a tube seat, the proximal end of the conduit body is fixedly connected to the tube seat, the tube seat is provided with a push channel and a slide groove communicating with the push channel, and the proximal end of the elastic element extends into the slide groove through the push channel; The operating end includes a push block that is slidably sleeved onto the outside of the tube seat. A portion of the push block is located within the groove and abuts against the proximal end of the elastic element.

[0025] With the above configuration, the push channel within the tube seat perfectly matches the constraint cavity structure of the sheath tube. The proximal end of the elastic element extends into the groove via the push channel. The push channel restricts the radial displacement and torsional movement of the elastic element throughout its entire length, ensuring that the elastic element always moves along the axial axis during axial advancement. The portion of the push block located within the groove can be provided with circumferentially corresponding abutment surfaces for each elastic element, with the proximal ends of multiple elastic elements tightly abutting their respective abutment surfaces. When the push block moves axially, the abutment surfaces synchronously apply driving force to all elastic elements, ensuring that the advancement speed and stroke of each elastic element are completely consistent.

[0026] In addition, the axial length of the groove can precisely limit the maximum sliding stroke of the push block, which is perfectly matched with the maximum safe extension length of the elastic element. When the push block slides to the end of the groove, it will be mechanically limited by the groove wall and cannot continue to advance, thereby avoiding the tearing of the elastic sleeve, deformation of the return bend, or damage to blood vessels caused by excessive extension of the elastic element.

[0027] Optionally, the fixed end also includes a fixing block, which is sleeved and fixed outside the tube seat. The inner side of the fixing block has a pressing part, which presses against the outer surface of the elastic element located in the groove.

[0028] With the above settings, the pressing part of the fixing block is pressed against the outer surface of the elastic element located in the slide groove. The pre-tightening force eliminates the assembly gap between the elastic element and the slide groove and the pushing channel, and firmly fixes the elastic element in the central axis position of the "pushing channel-slide groove". This prevents radial movement, torsion or axial slippage during the axial advancement process, and ensures that the movement trajectory of the elastic element is completely coincident with the axis of the guide tube body, thereby strengthening the coaxiality of the guide channel.

[0029] Optionally, a guide ring groove is provided at the end of the push block facing the fixed block, and a guide ring is provided at the end of the fixed block facing the push block, with the guide ring and the guide groove being inserted into each other.

[0030] With the above settings, the guide ring groove and guide ring work together to guide the pushing process during the pushing of the push block, thereby improving the accuracy of the movement.

[0031] Optionally, the outer periphery of the push block is the push operation surface, which expands outward along the push direction.

[0032] With the above settings, the expanded push surface makes it easier for doctors to hold the push block and apply force in the desired push manner, making the operation more convenient.

[0033] Optionally, the push channel is inclined and forms an acute angle with the push direction. The proximal end of the elastic element includes an inclined section and a straight section, with the inclined section located within the push channel and the straight section located within the groove.

[0034] With the above settings, the push channel can better guide the proximal end of the elastic element to extend outward, reduce the degree of bending of the proximal end of the elastic element, and the straight section located in the groove can better transmit the thrust. Attached Figure Description

[0035] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a radial cross-sectional view of the reverse microcatheter according to an embodiment of this application; Figure 2 This is a schematic cross-sectional view of the reverse microcatheter along the axial direction of the elastic element in the initial state according to the embodiments of this application; Figure 3 This is a schematic cross-sectional view of the reverse microcatheter in the expanded state according to the embodiments of this application. Figure 4 This is a schematic diagram of the elastic element in its natural state according to the embodiments of this application; Figure 5 This is a cross-sectional structural diagram of the operating part according to an embodiment of this application.

[0036] The components include: 1. Catheter body; 100. Consumable channel; 110. Inner tube; 111. PTFE tube; 112. Braided wire; 120. Outer tube; 130. Sheath tube; 140. Constraint cavity; 2. Elastic element; 200. Stabilizing section; 210. Expansion section; 220. Bending section; 3. Elastic sleeve; 4. Operating section; 40. Fixed end; 400. Tube seat; 4001. Slide groove; 4002. Pushing channel; 401. Fixed block; 4010. Crimping section; 41. Operating end; 410. Pushing block; 4100. Pushing operating surface; 4101. Guide ring groove. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate for the embodiments of this application described herein.

[0039] In this application, the terms "upper," "lower," "inner," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily used to better describe this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0040] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0041] Furthermore, the terms "set up," "equipped with," "connected," and "fixed" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0042] In addition, the term "multiple" should mean two or more.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] To solve related technical problems, such as Figures 1 to 4 As shown, this embodiment provides a retrograde microcatheter for interventional therapy, comprising: a catheter body 1 having a through consumable channel 100 for interventional consumables to pass through, wherein in retrograde CTO, the consumable channel 100 is used for at least the passage of a retrograde guidewire and a forward guidewire. A constraint cavity 140 is provided within the wall of the catheter body 1, the constraint cavity 140 being arranged along an axial direction parallel to the catheter body 1, and multiple constraint cavities 140 are provided and distributed circumferentially along the catheter body 1. Figure 1 As shown, eight constraint cavities 140 are evenly arranged circumferentially on the main body of the catheter 1.

[0045] The elastic element 2 is pre-shaped as intended. As an example, the elastic element 2 is pre-shaped in its natural state as follows: Figure 4 The shape shown includes at least two straight segments and an inclined segment connecting the two straight segments. The inclined segment is located at the distal end of the elastic member 2. After the inclined segment is constrained to overcome the elastic force and is flush with the straight segments, the inclined segment stores elastic potential energy. After the constraint is released, the inclined segment releases the elastic potential energy and expands outward. In this embodiment, the elastic member 2 is at least partially located within the constraint cavity 140 and is slidably connected to the constraint cavity 140, such as... Figure 2 As shown, the distal end of the elastic member 2 has an initial state constrained by the constraint cavity 140, that is, after the inclined section is completely located within the constraint cavity 140, the constraint cavity 140 constrains its elastic potential energy to be released. At this time, the inclined section and the straight section remain flush. Figure 3 As shown, the distal end of the elastic member 2 also has an expansion state in which it is detached from the constraint cavity 140 and expands under its own elastic force, that is, at least a part of the inclined section extends out of the constraint cavity 140 to the distal end, releasing elastic potential energy and expanding outward.

[0046] An elastic sleeve 3 is connected to the distal end of the catheter body 1. The elastic sleeve 3 can be made of super-elastic silicone material with a large elastic elongation. Figure 2 and Figure 3 As shown, the elastic sleeve 3 has a cavity, and the distal end of the elastic member 2 is configured to extend operably into the cavity of the elastic sleeve 3. When the distal end of the elastic member 2 extends out of the constraint cavity 140, it is in an expanded state. The distal end of the elastic member 2 will stretch the elastic sleeve 3 and cause the elastic sleeve 3 to expand outward synchronously. The expanded elastic sleeve 3 is continuous in the circumferential direction. After abutting against the inner wall of the forward conduit, the forward guide wire located in the forward conduit can pass through the elastic sleeve 3 and enter the consumable channel 100 of the conduit body 1.

[0047] In this embodiment, during use, the reverse microcatheter first maintains the elastic element 2 in its initial state, completely constrained by the constraint cavity 140. The reverse guidewire passes through the consumable channel 100 within the catheter body 1 and reverses through the occluded section into the forward catheter. The catheter body 1 is pushed along the reverse guidewire through the occluded section, allowing the elastic sleeve 3 to enter the forward catheter. Then, the elastic element 2 is manipulated so that its distal end at least partially extends out of the constraint cavity 140. After disengaging from the constraint cavity 140, it releases elastic potential energy and expands outward, simultaneously stretching the elastic sleeve 3 outward and abutting against the inner wall of the forward catheter, thereby constructing a channel between the forward catheter and the catheter body 1. The forward guidewire located within the forward catheter can smoothly enter the consumable channel 100 of the catheter body 1 and pass through the occluded section along the consumable channel 100. Then, the reverse microcatheter is withdrawn, and the forward catheter passes through the occluded section along the forward guidewire.

[0048] In this embodiment, through the above-mentioned settings, on the one hand, when the elastic element 2 is removed from the constraint cavity 140 by operation, its distal end enters an expansion state under its own elastic force, thereby stretching the elastic sleeve 3 sleeved on the distal end of the catheter body 1, so that the elastic sleeve 3 expands radially outward and tightly abuts against the inner wall of the antegrade catheter, forming a stable axial guide channel, which limits the travel path of the antegrade guidewire to the coaxial range between the elastic sleeve 3 and the consumable channel 100 of the catheter body 1, effectively avoiding the problem of guidewire deviation, jamming or mis-entry into branches in complex vascular environments (such as tortuous vessels, branch vessels or proximal occlusion lesions), significantly reducing the difficulty of antegrade guidewire entering the consumable channel 100 of the catheter body 1, and improving the accuracy and efficiency of guidewire puncture, especially suitable for complex coronary artery surgery scenarios such as CTO intervention; On the other hand, by using the built-in constraint cavity 140 in the tube wall, the expansion process only requires pushing the elastic element 2 to slide along the constraint cavity 140 to trigger the expansion of the elastic sleeve 3. There is no need to configure the movable sleeve used to constrain / release the elastic element 2 in the traditional design, thereby maximizing the release of the internal space of the conduit body 1 and significantly increasing the effective diameter of the consumable channel 100.

[0049] In some embodiments, the elastic element 2 is configured to have two or more expansion states, and the elastic sleeve 3 has different maximum outer diameters in different expansion states. Through the above configuration, the elastic element 2 can drive the elastic sleeve 3 to stretch and expand to different maximum outer diameters in different expansion states, which can accurately adapt to the needs of different catheter diameters in interventional surgery, maintain the stability of the constructed guide channel, and avoid the elastic sleeve 3 from loosening due to changes in catheter diameter.

[0050] In some embodiments, such as Figures 2 to 4As shown, the elastic element 2 includes a stabilizing section 200 and an expanding section 210. The expanding section 210 is connected to the distal end of the stabilizing section 200. The stabilizing section 200 is the part of the elastic element 2 with the same shape in both the constrained and natural states. The expanding section 210 is the part of the elastic element 2 with different shapes in both the constrained and natural states, wherein in the natural state, it is in an outwardly expanding shape relative to the constrained state. During the expansion process, the stabilizing section 200 can always remain within the constrained cavity 140.

[0051] In the initial state, the stabilizing segment 200 and the expanding segment 210 are located within the constraining cavity 140, with the expanding segment 210 constrained by the constraining cavity 140, ensuring that both the expanding segment 210 and the stabilizing segment 200 are aligned and aligned. In the expanding state, at least a portion of the expanding segment 210 extends beyond the distal end of the constraining cavity 140 and expands under its own elastic force. Within a preset expansion range, as the length of the expanding segment 210 extending beyond the constraining cavity 140 increases, the degree of expansion of the expanding segment 210 increases, and the degree of expansion of the elastic sleeve 3 increases accordingly. In other words, within the preset expansion range, the expansion state can be controlled by controlling the length of the expanding segment 210 extending beyond the constraining segment, thereby controlling the maximum diameter of the elastic sleeve 3.

[0052] In this embodiment, through the above-mentioned settings, on the one hand, the stabilizing section 200 always remains within the constraint cavity 140 and is slidably connected to the constraint cavity 140. Its rigid structure provides a fixed motion reference for the expansion section 210. When the elastic element 2 is pushed, the stabilizing section 200 slides smoothly along the axial direction of the constraint cavity 140, ensuring that the expansion section 210 extends only along the axial direction of the catheter body 1 without radial offset or swaying. The expansion section 210 is specifically designed to perform the function of "elastic expansion after release from constraint," without the need to consider support and guidance. More suitable elastic materials (such as shape memory alloy wire, high-elasticity medical plastic) and structures can be used to make the expansion force more concentrated and the expansion shape more regular. At the same time, the constraint effect of the stabilizing section 200 prevents the expansion section 210 from expanding prematurely before it is fully extended, ensuring that the expansion force is entirely applied to the stretching of the elastic sleeve 3, improving the uniformity and reliability of the expansion of the elastic sleeve 3. On the other hand, doctors can precisely control the extension length of the dilation segment 210 by controlling the stroke of the elastic element 2, thereby controlling the outward expansion of the elastic sleeve 3 and avoiding the uncontrollability of the traditional elastic element 2 which expands completely after being pushed. For example, in a small-diameter catheter, only a small stroke is needed to slightly extend the dilation segment 210, and the elastic sleeve 3 can be slightly expanded to fit the inner wall of the blood vessel; in a large-diameter catheter or when large consumables need to be delivered, a larger stroke is needed to fully extend the dilation segment 210, and the elastic sleeve 3 expands to the maximum extent to achieve stable support.

[0053] On the other hand, the expansion state of the elastic element 2 can be precisely controlled by a single operation (such as pushing the elastic element 2 to adjust its stroke). The operation logic is simple and intuitive, and doctors do not need to learn complicated instrument control methods to quickly master the outer diameter adjustment skills. On the other hand, the supporting effect of the stabilizing segment 200 makes the expansion of the elastic sleeve 3 more uniform, further improving the coaxiality of the guide channel. Together with the expanded consumable channel 100, it makes the advancement of large-diameter interventional consumables smoother. The fine expansion adjustment brought by the variable extension length allows the elastic element 2 to adapt to blood vessels of different diameters and to be dynamically adjusted throughout the entire surgical procedure, avoiding surgical interruptions caused by changing instruments. Together with the "no movable cannula required" design, it simplifies the instrument structure and improves surgical efficiency and safety.

[0054] In some embodiments, such as Figures 2 to 4 As shown, the distal end of the elastic element 2 is provided with a bend 220, which has an arc or hook-shaped structure. The bend 220 prevents the distal end face of the elastic element 2 from directly abutting against the inner wall of the elastic sleeve 3. In the expanded state, the bend 220 abuts against the inner wall of the elastic sleeve 3. In this embodiment, the above arrangement provides a large contact area between the bend 220 and the distal inner end face of the elastic sleeve 3, providing stable support for the elastic sleeve 3 when passing through the blocking section in reverse and preventing stress concentration that could puncture the elastic sleeve 3. During the extension of the elastic element 2, the large contact area between the bend 220 and the elastic sleeve 3 disperses the expansion pressure of the elastic element 2 to multiple areas of the inner wall of the elastic sleeve 3, preventing excessive local pressure that could lead to material fatigue, tearing, or permanent deformation of the elastic sleeve 3. Especially in multi-level expansion states, even if the elastic sleeve 3 is significantly stretched, the uniform force of the bend 220 ensures that the elastic sleeve 3 always operates within a safe elastic range.

[0055] On the other hand, in the expanded state, the contact between the bend 220 and the inner wall of the elastic sleeve 3 forms an "internal support skeleton", which allows the elastic sleeve 3 to not only expand outward by its own elasticity, but also resist the compression of the inner wall of the blood vessel or the pushing pressure of the interventional consumables through the rigid support of the bend 220.

[0056] In one embodiment, the elastic element 2 is a metal wire. The metal wire possesses both moderate rigidity and elasticity, providing sufficient radial expansion force during expansion to push the elastic sleeve 3 outwards uniformly along the circumference, forming a regular circular guide channel; it also avoids excessive rigidity leading to localized stress concentration in the elastic sleeve 3. Furthermore, the metal wire is highly malleable, allowing for precise bending to create arc-shaped, hook-shaped, or other bend structures 220, which remain stable after forming and do not deform at the bend angle during expansion or retraction. The reliable bend structure 220 forms a stable multi-point contact with the inner wall of the elastic sleeve 3, dispersing pressure through the contact surface and reducing the risk of damage to the elastic sleeve 3. On the other hand, the diameter of the metal wire can be precisely controlled. Compared with the traditional plastic elastic element 2, the thinner diameter metal wire occupies less space in the constraint cavity 140, and there is no need to reserve too much radial space for the elastic element 2, thereby further freeing up the internal space of the catheter body 1. Combined with the design of "the constraint cavity 140 built into the tube wall and no additional movable sleeve", the effective diameter of the consumable channel 100 is maximized, ensuring the smooth passage of large-diameter interventional consumables. In addition, multiple metal wire elastic elements 2 (matching the number of constraint cavities 140) can be set along the circumference of the catheter body 1. Each metal wire independently bears part of the expansion force, which can improve the uniformity of the expansion of the elastic sleeve 3 through multi-point support, and will not occupy too much space due to the large diameter of a single metal wire. This achieves a balance between enhanced support force and compact space, which is suitable for the core requirements of small outer diameter and multi-functionality of minimally invasive interventional instruments.

[0057] In one embodiment, the elastic element 2 is a metal flat wire. On the one hand, when the metal flat wire is in an expanded state, there is more contact area between the metal flat wire and the elastic sleeve 3, so that the expansion force can be evenly distributed to the circumferential direction of the inner wall of the elastic sleeve 3, avoiding uneven stretching of the elastic sleeve 3 caused by local force concentration, ensuring that the elastic sleeve 3 always forms a regular circular guide channel, reducing friction and jamming when the guide wire and interventional consumables are advanced, especially suitable for the smooth passage of large-diameter consumables; and, the metal flat wire has a smaller radial thickness, reducing the radial space occupied, which can further reduce the radial dimension of the constraint cavity 140, thereby maximizing the release of the internal space of the catheter body 1; On the other hand, after the elastic element 2 is set as a flat metal wire, its flat cross section makes it less prone to torsion and slippage during axial sliding and radial expansion. When the flat wire of the stable section 200 slides along the constraint cavity 140 axially, the flat structure has a higher degree of fit with the inner wall of the constraint cavity 140 and the movement trajectory is more accurate, ensuring that the expansion section 210 extends only along the axial direction and does not have the "spiral offset" that is common with round wires. This further ensures the coaxiality of the elastic sleeve 3 and the consumable channel 100 and improves the accuracy of the guide wire guidance. On the other hand, the flat cross-section of the metal flat wire is easier to process and shape through precision bending, laser cutting and other processes. In particular, the preset shape of the expansion section 210 and the arc structure of the return bend 220 have a dimensional accuracy that is much higher than that of the round wire. This ensures that the expansion shape and return bend angle of multiple elastic elements 2 are completely consistent, and the tension on the elastic sleeve 3 is uniform and synchronous during expansion, avoiding the tilting or irregular expansion of the elastic sleeve 3 caused by the forming deviation of a single elastic element 2.

[0058] In one implementation, such as Figure 1As shown, the elastic element 2 has a flat rectangular cross-section in the radial direction of the conduit body 1. With this flat rectangular cross-section, the elastic element 2 has a higher degree of fit with the inner wall of the constraint cavity 140, and its geometry can effectively restrict the torsional movement of the elastic element 2 within the constraint cavity 140, improving the accuracy of the movement trajectory and further enhancing the coaxiality of the elastic sleeve 3 and the consumable channel 100. Furthermore, the long side of the flat rectangular cross-section is distributed circumferentially along the conduit body 1, allowing multiple elastic elements 2 to be arranged closely without requiring excessive circumferential gaps. With the same conduit outer diameter, more elastic elements 2 can be arranged to achieve multi-point support.

[0059] Optionally, such as Figure 1 As shown, the catheter body 1 includes: an inner tube 110 having a through consumable channel 100 for interventional consumables to pass through; an outer tube 120, which is sleeved and fixed outside the inner tube 110, and the inner tube 120 has multiple circumferentially distributed installation cavities in its inner wall, which are arranged parallel to the axial direction of the outer tube 120; and a sheath tube 130, which is embedded and fixed in the installation cavity, and the sheath tube 130 has a restraint cavity 140.

[0060] In this embodiment, through the above-mentioned configuration, the inner tube 110 independently undertakes the core function of allowing interventional consumables to pass through. It can be made of low-friction, high-smoothness medical materials (such as PTFE, PEEK) and its inner diameter can be precisely controlled to maximize the smoothness and effective diameter of the consumable channel 100. The outer tube 120 is sleeved and fixed outside the inner tube 110 to form a rigid support skeleton. Multiple installation cavities distributed circumferentially within its tube wall provide a precise installation reference for the sheath tube 130. The outer tube 120 can be made of medical tubing with moderate rigidity, which ensures the overall structural strength of the catheter body 1 and prevents bending or deformation under pressure within the blood vessel. It can also ensure the uniform circumferential distribution of multiple installation cavities through precision machining, laying the foundation for the synchronous movement of the elastic element 2 and the uniform expansion of the elastic sleeve 3. The sheath tube 130 is embedded and fixed within the installation cavity. Its internal constraint cavity 140 is specifically adapted to the structural shape of the elastic element 2. The elastic element 2 and the constraint cavity 140 can be overfitted together, thereby providing a stable constraint on the elastic element 2. The side of the sheath tube 130 facing the inner tube 110 can be set as an arc surface, thereby improving the surface fit between the sheath tube 130 and the inner tube 110. In this embodiment, the dedicated cavity design avoids direct contact between the elastic element 2 and the inner tube 110 and the outer tube 120, concentrating the constraint function on the sheath tube 130, and ensuring that the sliding and expanding movements of the elastic element 2 always follow the preset trajectory.

[0061] In one embodiment, the inner tube 110 comprises a two-layer structure, consisting of a PTFE tube 111 located in the middle and braided wires 112 wound around the PTFE tube 111. The outer tube 120 may be made of Pebax material.

[0062] In some embodiments, such as Figure 5As shown, the reverse microcatheter also includes an operating part 4, connected to the proximal end of the catheter body 1. The operating part 4 includes a fixed end 40 and an operating end 41. The fixed end 40 is fixedly connected to the proximal end of the catheter body 1, for example, the proximal end of the catheter body 1 is inserted into the fixed end 40 and fixed by welding or bonding. The operating end 41 is configured to be operably movable relative to the fixed end 40 along the axial direction of the catheter body 1. The operating end 41 can be sleeved outside the fixed end 40, and the operating end 41 and the fixed end 40 can be slidably connected. The proximal end of the elastic element 2 extends out of the catheter body 1 and is connected to the operating end 41. The operating end 41 drives the elastic element 2 to move toward the distal end. As shown, the elastic element 2 extends radially outward through the side of the catheter body 1 and is connected to the operating end 41. The operating end 41 applies a thrust to the elastic element 2, driving the distal end of the elastic element 2 to extend out of the constraint cavity 140 and be in an expanded state.

[0063] In this embodiment, with the above-mentioned settings, the operating end 41 moves only along the axial direction of the catheter body 1, and the driving force is directly converted into the axial advancement of the elastic element 2. The operation action and the expansion effect of the elastic sleeve 3 form a "linear correspondence". That is, the further the operating end 41 is pushed, the longer the elastic element 2 extends, and the greater the expansion amplitude of the elastic sleeve 3. There is no need for complex force transmission and conversion. The intuitive operation logic allows doctors to directly predict the expansion effect through the "pushing stroke" and confirm it with intraoperative imaging, reducing the learning and operation difficulty. It is especially suitable for interventional scenarios with limited surgical field and narrow operating space.

[0064] In one implementation, such as Figure 5 As shown, the fixed end 40 includes a tube seat 400, which has a channel that communicates with the consumable channel 100 inside the catheter body 1, allowing guidewire-type interventional consumables to enter the consumable channel 100 from the proximal end of the tube seat 400. The proximal end of the catheter body 1 is fixedly connected to the tube seat 400, for example, by insertion and fixation within the channel of the tube seat 400. The tube seat 400 is provided with a push channel 4002, which is structurally perfectly matched to the constraint cavity 140 of the sheath tube 130. The outer wall of the tube seat 400 is provided with a groove 4001 that communicates with the push channel 4002. The proximal end of the elastic member 2 extends out of the catheter body 1 and then extends through the push channel 4002 into the groove 4001. The operating end 41 includes a push block 410, which is a rigid structure. The push block 410 is slidably sleeved to the outside of the tube seat 400. A part of the push block 410 is located in the groove 4001 and abuts against the proximal end of the elastic member 2.

[0065] In this embodiment, through the above-described configuration, the pushing channel 4002 restricts the radial displacement and torsional movement of the elastic element 2 throughout its entire length, ensuring that the elastic element 2 always moves along the axis during axial advancement. The portion of the pushing block 410 located within the groove 4001 can be provided with circumferentially corresponding abutment surfaces to the elastic elements 2, with the proximal ends of multiple elastic elements 2 respectively tightly abutting against their corresponding abutment surfaces. When the pushing block 410 moves axially, the abutment surfaces synchronously apply driving force to all elastic elements 2, ensuring that the advancement speed and stroke of each elastic element 2 are completely consistent.

[0066] In addition, the axial length of the slide 4001 can precisely limit the maximum sliding stroke of the push block 410, which is perfectly matched with the maximum safe extension length of the elastic element 2. When the push block 410 slides to the end of the slide 4001, it will be mechanically limited by the wall of the slide 4001 and cannot continue to advance, thereby avoiding the tearing of the elastic sleeve 3, deformation of the bend 220 or damage to blood vessels caused by the excessive extension of the elastic element 2.

[0067] In one embodiment, the fixed end 40 further includes a fixed block 401, which is sleeved and fixed to the outside of the tube seat 400. The inner side of the fixed block 401 has a pressing part 4010, which presses against the outer surface of the portion of the elastic member 2 located in the slide groove 4001. With the above arrangement, the pressing part 4010 of the fixed block 401 presses against the outer surface of the elastic member 2 located in the slide groove 4001. By pre-setting a pre-tightening force, the assembly gap between the elastic member 2 and the slide groove 4001 and the push channel 4002 is eliminated, and the elastic member 2 is firmly fixed at the central axis position of "push channel 4002-slide groove 4001", avoiding radial movement, torsion or axial slippage during axial advancement, ensuring that the movement trajectory of the elastic member 2 is completely coincident with the axis of the guide tube body 1, and strengthening the coaxiality of the guide channel.

[0068] In one implementation, such as Figure 5 As shown, the end of the pushing block 410 facing the fixed block 401 is provided with a guide ring groove 4101, and the end of the fixed block 401 facing the pushing block 410 is provided with a guide ring, which is inserted into the guide groove. Through the above arrangement, the pushing process is guided by the cooperation of the guide ring groove 4101 and the guide ring during the pushing process of the pushing block 410, thereby improving the accuracy of the movement.

[0069] In one implementation, such as Figure 5 As shown, the outer peripheral surface of the push block 410 is the push operation surface 4100, which expands outward along the push direction. With this design, the expanded push operation surface 4100 makes it easier for doctors to hold the push block and apply force in the desired pushing manner, making operation more convenient.

[0070] In one implementation, such as Figure 5As shown, the push channel 4002 is inclined and forms an acute angle with the push direction. The proximal end of the elastic member 2 includes an inclined section and a straight section. The inclined section is located within the push channel 4002, and the straight section is located within the groove 4001. With the above arrangement, the push channel 4002 can better guide the proximal end of the elastic member 2 to extend outward, reducing the degree of bending at the proximal end of the elastic member 2. The straight section located within the groove 4001 can better transmit the thrust.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A retrograde microcatheter for interventional therapy, characterized in that, include: The catheter body has a through consumable channel for interventional consumables to pass through. A constraint cavity is provided inside the wall of the catheter body. The constraint cavity is arranged along the axial direction parallel to the catheter body, and multiple constraint cavities are provided and distributed along the circumference of the catheter body. An elastic element, at least partially located within and slidably connected to the constraint cavity, has an initial state constrained by the constraint cavity at its distal end, and an expanded state in which it is freed from constraint and expands under its own elastic force. An elastic sleeve is disposed at the distal end of the catheter body, and the distal end of the elastic element is configured to extend operably into the elastic sleeve. In the expanded state, the elastic element stretches the elastic sleeve and expands the elastic sleeve outward. An operating section includes a fixed end and an operating end, the fixed end being connected to the proximal end of the catheter body, the operating end being configured to be operably movable relative to the fixed end along the axial direction of the catheter body, and the proximal end of the elastic element extending out of the catheter body and connected to the operating end.

2. The reverse microcatheter according to claim 1, characterized in that, The elastic element is configured to have two or more expansion states, and the elastic sleeve has a different maximum outer diameter in different expansion states.

3. The reverse microcatheter according to claim 2, characterized in that, The elastic element includes a stabilizing section and an expanding section, the expanding section being connected to the distal end of the stabilizing section. In the initial state, the stabilizing section and the expanding section are located within the constraint cavity, and the expanding section is constrained by the constraint cavity. In the expanding state, at least a portion of the expanding section extends beyond the distal end of the constraint section and expands under its own elastic force. In different expanding states, the length by which the expanding section extends beyond the distal end of the constraint section is different.

4. The reverse microcatheter according to claim 3, characterized in that, The distal end of the elastic element is provided with a return bend, which abuts against the inner wall of the elastic sleeve in the expanded state.

5. The reverse microcatheter according to claim 1, characterized in that, The elastic element is a metal wire.

6. The reverse microcatheter according to claim 5, characterized in that, The elastic element is a flat metal wire.

7. The reverse microcatheter according to claim 6, characterized in that, The elastic element has a flat rectangular cross-section in the radial direction of the catheter body.

8. The reverse microcatheter according to claim 1, characterized in that, The catheter body includes: The inner tube has a through-flow consumable channel through which interventional consumables pass; An outer tube is sleeved and fixed outside the inner tube. The inner wall of the outer tube is provided with a plurality of mounting cavities distributed circumferentially. The mounting cavities are arranged parallel to the axial direction of the outer tube. A sheath tube is embedded and fixed inside the mounting cavity, and the constraint cavity is provided inside the sheath tube.

9. The reverse microcatheter according to claim 1, characterized in that, The fixed end includes a tube seat, the proximal end of the conduit body is fixedly connected to the tube seat, the tube seat is provided with a push channel and a slide groove communicating with the push channel, and the proximal end of the elastic element extends into the slide groove through the push channel; The operating end includes a push block that is slidably sleeved onto the outside of the tube seat, and a portion of the push block is located within the groove and abuts against the proximal end of the elastic member.

10. The reverse microcatheter according to claim 9, characterized in that, The fixed end also includes a fixing block, which is sleeved and fixed outside the tube seat. The inner side of the fixing block has a pressing part, which is pressed against the outer surface of the portion of the elastic element located in the groove.

11. The reverse microcatheter according to claim 10, characterized in that, The push block has a guide ring groove at one end facing the fixed block, and the fixed block has a guide ring at one end facing the push block. The guide ring is inserted into the guide groove.

12. The reverse microcatheter according to claim 11, characterized in that, The outer peripheral surface of the push block is the push operation surface, which expands outward along the push direction.

13. The reverse microcatheter according to claim 12, characterized in that, The push channel is inclined and forms an acute angle with the push direction. The proximal end of the elastic element includes an inclined section and a straight section. The inclined section is located within the push channel, and the straight section is located within the groove.

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