A nested contrast catheter and contrast catheter system

Abstract

This application relates to a nested angiography catheter and an angiography catheter system. The nested angiography catheter includes an inner angiography catheter and an outer cannula. The inner angiography catheter is used for superselective entry into the vertebral artery orifice via a radial approach and is advanced to the distal end of the vertebral artery. The inner angiography catheter includes a lumen for injecting contrast agent. The outer cannula is nested outside the inner angiography catheter and can be coaxially advanced relative to the inner angiography catheter. The outer cannula can be advanced through the vertebral artery orifice and reach the distal target position at the C4-C5 level of the vertebral artery. The length of the inner angiography catheter is greater than the length of the outer cannula. An anti-reflux gap is formed between the outer cannula and the inner angiography catheter. The anti-reflux gap is configured to form a fluid barrier structure that prevents the contrast agent from flowing back to the proximal end during injection. The anti-reflux gap in this application can reduce the contrast agent reflux rate, reduce the amount of contrast agent used, avoid continuous stimulation of the vessel wall, and stably anchor the vertebral artery orifice, thereby improving diagnostic accuracy.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and more specifically, to a nested angiography catheter and angiography catheter system. Background Technology

[0002] The existing catheters used for posterior circulation angiography via the radial approach are mainly general-purpose 5F single-lumen nerve angiography catheters. In a few scenarios, they are used in conjunction with conventional guiding catheters or long sheaths. There are no nested coaxial cannula angiography catheters specifically designed for posterior circulation angiography via the radial approach.

[0003] (1) Conventional single-lumen angiography catheters include a single lumen and a single hardness segment (usually 60-70D uniform throughout), and can only be superselected with the assistance of guidewires, without an independent outer cannula structure.

[0004] (2) The coaxial delivery system for treatment consists of a guiding tube and a microcatheter. Its main purpose is to serve as a delivery channel for intracranial vascular interventional therapy (thrombectomy, embolization, drug administration). It has not been structurally optimized to meet the specific needs of contrast agent anti-reflux and distal imaging optimization.

[0005] (3) Single-section multi-hardness catheter: Some catheters undergo multi-section hardness transitions between soft-tip end and hard-support end within a single tube body, but still have a single tube structure and no concept of outer tube nesting.

[0006] (4) Anti-reflux technology: Currently, the mainstream anti-reflux designs are concentrated on general solutions such as balloon occlusion and Y-valve hemostasis valve. There is no publicly available technology specifically for posterior circulation angiography with nested coaxial clearance fit and precision radial clearance.

[0007] The existing applications of the above-mentioned transradial approach have the following drawbacks: Single catheters provide insufficient support under complex aortic arch conditions: the radial path is long, usually 110-130 cm, and the tip of a traditional single-lumen angiography catheter is difficult to anchor stably to the vertebral artery opening. Contrast agent flows back in large quantities through the opening towards the aortic arch, with a contrast agent reflux rate as high as 42%. The distal basilar artery, posterior cerebral artery and other posterior circulation vessels are faintly visualized, affecting the accuracy of diagnosis.

[0008] Uniform hardness at the tip of a single catheter can easily induce vasospasm: The tip of a conventional catheter is a hard segment of 60-70D. When it enters the opening of the vertebral artery, it continuously stimulates the vessel wall, and the vasospasm induction rate reaches 11%. Spasm causes false stenosis artifacts in the vessel wall, which seriously interferes with the doctor's correct judgment of the lesion.

[0009] The single-lumen structure has poor anti-reflux capability: Once the contrast agent is injected into the single-lumen angiography catheter, the reflux pressure acts directly on the vessel wall without any buffer gap, resulting in a persistently high reflux rate; at the same time, the contrast agent can also enter the aortic arch after refluxing through the vertebral artery opening, which may affect the synchronous imaging observation of other vessels such as the thoracic aorta.

[0010] General coaxial systems are not optimized for angiography: Existing coaxial delivery systems for guiding catheters and microcatheters focus on the delivery channel for therapeutic devices. The overall outer diameter of 8-9F is relatively large, making it difficult to push via the radial approach.

[0011] Torque transmission lag: The radial approach is about 30 cm longer than the femoral artery approach. The torque transmission of a conventional single-lumen angiography catheter is significantly delayed, resulting in delayed operator response, longer superselection time, increased X-ray exposure time, and a corresponding increase in contrast agent usage. Summary of the Invention

[0012] The purpose of this application is to provide a nested angiography catheter and angiography catheter system, specifically a nested coaxial cannula angiography catheter for transradial intracranial posterior circulation angiography, which can solve at least one of the above-mentioned technical problems.

[0013] To achieve the above objectives, in a first aspect, the present invention provides a nested angiography catheter, comprising: an inner angiography catheter and an outer cannula, wherein the inner angiography catheter is used to superselectively enter the vertebral artery opening via a radial approach and push it to the distal end of the vertebral artery, and the inner angiography catheter includes a catheter lumen for injecting contrast agent. The outer cannula is nested outside the inner angiography catheter and can be pushed coaxially relative to the inner angiography catheter. The outer cannula can be advanced through the vertebral artery opening and reach the distal target position at the C4-C5 level of the vertebral artery. The length of the inner contrast catheter is greater than the length of the outer cannula. An anti-backflow gap is formed between the outer cannula and the inner contrast catheter. The anti-backflow gap is configured to form a fluid barrier structure that prevents the contrast agent from flowing back to the proximal end when the contrast agent is injected.

[0014] In an optional embodiment, the anti-backflow gap is disposed between the outer wall of the inner angiography catheter and the inner wall of the outer sheath, including a radial fitting gap between the inner angiography catheter and the outer sheath, the radial dimension of which is 0.02-0.03 mm.

[0015] In an optional embodiment, the intraneurography catheter includes a neuro-endoneurography catheter with an outer diameter of 5F and a length of 120-130cm. The outer diameter of the outer sleeve is 5.5-6.5F, and the length is 105-115cm; The radial gap between the inner diameter of the outer sheath and the outer diameter of the internal angiography catheter is 0.02-0.03 mm.

[0016] In an optional embodiment, the internal angiography catheter sequentially includes a proximal segment, a transition segment, and a tube head. The hardness of the proximal section is greater than that of the transition section, and the hardness of the transition section is greater than that of the tube head. The tube head is shaped to fit the opening of the vertebral artery.

[0017] In an optional embodiment, the internal angiography catheter includes a smooth outer wall surface; The hardness of the proximal section is Shore hardness 72-78D, the hardness of the transition section is Shore hardness 58-63D, and the hardness of the tube head is Shore hardness 25-33D or 80±10A.

[0018] In an optional embodiment, the outer sleeve includes a proximal support section, an intermediate transition section, and a distal flexible section; The distal soft segment includes a hydrophilic soft segment; The outer tube is provided with a developing ring at its distal end. The developing ring is located in the distal flexible section, and the developing ring is spaced 3-8 mm away from the distal opening of the distal flexible section. The hydrophilic soft segment has a Shore hardness of less than or equal to 35D, or the hydrophilic soft segment has a Shore hardness of 80±10A, and the proximal support segment has a Shore hardness of 72-78D.

[0019] In an optional embodiment, the proximal end of the internal angiography catheter is connected to an internal angiography catheter seat, the proximal end of the outer cannula is connected to an outer cannula seat, and the outer cannula seat is nested on the distal side of the internal angiography catheter seat.

[0020] In an optional implementation, the outer tube is configured after being pushed into place as follows: The distal end of the internal angiography catheter extends outward relative to the distal end of the outer cannula, or the distal end of the outer cannula extends outward relative to the distal end of the internal angiography catheter. The distance between the distal end of the internal angiography catheter and the distal end of the outer cannula does not exceed 5 mm.

[0021] In an optional implementation, after the outer cannula is advanced into place, it can be configured such that the distal end of the outer cannula is flush with the distal end of the internal angiography catheter.

[0022] Secondly, the present invention provides an angiography catheter system for use in post-radial circulatory angiography, including a radial artery sheath and a nested angiography catheter as described in any of the foregoing embodiments, wherein the inner angiography catheter is pushed to the distal end of the vertebral artery via the radial artery sheath, and the outer cannula is coaxially advanced along the inner angiography catheter to a distal target position at the C4-C5 level of the vertebral artery.

[0023] The nested angiography catheter and angiography catheter system in this application can reduce the reflux rate of contrast agent and reduce the amount of contrast agent used by forming an anti-reflux gap between the outer cannula and the inner angiography catheter, avoid continuous stimulation of the blood vessel wall, reduce the impact of vasospasm on lesion assessment, and at the same time, can stably anchor the vertebral artery opening and improve diagnostic accuracy.

[0024] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure of the nested angiography catheter in this application before application; Figure 2 This is a schematic diagram of the distal portion of the nested angiography catheter in application of this application; Figure 3 This is a schematic diagram of the outer jacket in this application.

[0027] icon: 1-Intra-angiography catheter; 11-Proximal segment; 12-Transition segment; 13-Catheter tip; 14-Intra-angiography catheter hub; 2-Outer sleeve; 21-Proximal support segment; 22-Intermediate transition segment; 23-Distal soft segment; 24-Iconizing ring; 25-Outer sleeve seat; 3- Anti-backflow gap. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] The nested angiography catheter and angiography catheter system involved in this application are mainly used in transradial intracranial posterior circulation angiography.

[0032] The specific procedure for intracranial posterior circulation angiography via the radial approach is as follows: a pathway is established through radial artery puncture, a catheter is superselectively inserted into the vertebral artery opening via the radial artery, and then advanced along the vertebral artery to the target location. Contrast agent is injected to visualize the vertebral artery and other posterior circulation vessels, which is used to diagnose diseases such as posterior circulation ischemia, vertebral artery stenosis or occlusion, aneurysm, and arteriovenous malformation.

[0033] Compared to the femoral artery approach, the radial approach has a longer path, usually 110-130cm, and passes through a complex aortic arch, which places higher demands on the catheter's support, torque transmission, and tip stability.

[0034] See Figure 1 and combined Figures 2-3 In view of the technical defects of the existing transradial approach, the main improvement direction of this application is to construct a nested coaxial cannula angiography catheter specifically for the transradial approach posterior circulation angiography scenario. Through the coaxial nesting cooperation of the inner angiography catheter 1 and the outer cannula 2, the inner angiography catheter 1 is responsible for the basic superselection of the vertebral artery orifice, and the outer cannula 2 is responsible for reaching the distal C4-C5 level of the vertebral artery and forming an anti-reflux barrier.

[0035] Meanwhile, the multi-segment rigid structure of the inner angiography catheter 1 reduces the risk of vasospasm, and the precise radial gap between the outer cannula 2 and the inner angiography catheter 1 forms a fluid barrier structure that prevents proximal reflux of contrast agent. This reduces the amount of contrast agent used, shortens the operation time, and is compatible with existing operator habits while reducing the reflux rate.

[0036] The nested angiography catheter and angiography catheter system provided in this application are particularly suitable for intracranial posterior circulation angiography via the radial approach. The nested angiography catheter includes an inner angiography catheter 1 and an outer cannula 2. The inner angiography catheter 1 is used for superselective access to the vertebral artery orifice via the radial approach and can be further advanced to the distal end of the vertebral artery. The inner angiography catheter 1 includes a catheter lumen for injecting contrast agent.

[0037] The outer cannula 2 is nested outside the inner angiography catheter 1 and can be pushed coaxially relative to the inner angiography catheter 1. The outer cannula 2 can be advanced through the vertebral artery opening and reach the distal target position at the C4-C5 level of the vertebral artery.

[0038] The length of the inner contrast catheter 1 is greater than the length of the outer tube 2. An anti-backflow gap 3 is formed between the outer tube 2 and the inner contrast catheter 1. The anti-backflow gap 3 is configured to form a fluid barrier structure that prevents the contrast agent from flowing back to the proximal end when the contrast agent is injected.

[0039] This application utilizes the coaxial nesting of the inner angiography catheter 1 and the outer cannula 2, allowing the outer cannula 2 to advance along the inner angiography catheter 1 to the C4-C5 level of the vertebral artery, thereby creating a more stable anchoring position distal to the vertebral artery. During contrast agent injection, the anti-reflux gap 3 between the outer cannula 2 and the inner angiography catheter 1 forms a fluid barrier, preventing a large amount of contrast agent from flowing back through the vertebral artery opening proximally, or even towards the aortic arch, thereby improving the visualization clarity of posterior circulation vessels such as the vertebral artery, basilar artery, and posterior cerebral artery.

[0040] The endovascular catheter 1 can adopt a multi-segment rigid structure, so that the proximal end of the endovascular catheter 1 has sufficient support, the transition segment 12 takes into account the pushability, and the tip remains soft, thereby reducing the continuous stimulation of the vessel wall when entering the vertebral artery opening, reducing the induction rate of vasospasm, and reducing the interference of false stenosis artifacts on the judgment of lesions.

[0041] This application does not rely on common structures such as balloon occlusion or Y-valve hemostasis, but instead forms an anti-reflux barrier through a precise radial fit gap between the outer cannula 2 and the inner contrast catheter 1. The barrier structure formed by the precise radial fit gap does not add any additional complex operation, and can hinder the flow of reflux when the contrast agent is injected under high pressure, thereby reducing contrast agent waste and lowering the total amount of contrast agent used during the operation.

[0042] This application limits the radial fit gap between the outer cannula 2 and the inner contrast catheter 1 to a small range and controls its overall outer diameter to a range suitable for radial approach. Compared with existing coaxial delivery systems for treatment, it focuses more on preventing contrast agent backflow and optimizing distal imaging, rather than simply serving as a delivery channel for treatment devices.

[0043] By coordinating the internal angiography catheter 1 and the outer cannula 2, the internal angiography catheter 1 can first perform superselection of the vertebral artery orifice, and then the outer cannula 2 can be advanced coaxially along the internal angiography catheter 1 to the target position. The operation method conforms to the existing operator habits, which can shorten the superselection arrival time and reduce X-ray exposure time and contrast agent usage.

[0044] From the perspective of the composition of the anti-backflow gap 3 and the fluid dynamics mechanism, the anti-backflow gap 3 in this application is set between the outer wall of the inner angiography catheter 1 and the inner wall of the outer tube 2. The anti-backflow gap 3 is set between the outer wall of the inner angiography catheter 1 and the inner wall of the outer tube 2, including the radial fitting gap between the inner angiography catheter 1 and the outer tube 2. Specifically, the radial fitting gap is an annular gap set between the outer wall of the inner angiography catheter 1 and the inner wall of the outer tube 2, and the radial dimension of the annular gap is 0.02-0.03mm.

[0045] The radial fit gap in this application is not a physical space gap setting, but a flow obstruction setting based on the high flow resistance barrier mechanism in fluid mechanics. Furthermore, the determination of the aforementioned radial dimension range is closely related to the composition and physical properties of the clinical contrast agent.

[0046] In existing coaxial delivery systems for therapeutic applications, the catheter gap allows for rapid backflow of contrast agent, exacerbating contrast agent waste and insufficient distal imaging. This application controls the radial fit gap to within the range of 0.02-0.03 mm, creating a more precise radial fit between the outer cannula 2 and the inner angiography catheter 1. During high-pressure injection of the contrast agent, this precise radial gap forms a fluid barrier, preventing proximal backflow. In other words, the contrast agent is primarily injected distally through the lumen of the inner angiography catheter 1, while the smaller gap between the outer cannula 2 and the inner angiography catheter 1 creates a throttling effect on backflow, thereby reducing the probability of contrast agent backflow through the vertebral artery opening towards the aortic arch.

[0047] The radial gap range in this application is not arbitrarily selected, but rather a specific selection based on the composition and physical properties of the clinical contrast agent. Iodine contrast agents used for transradial post-circuit contrast imaging (such as iohexol, iodofol, iodixanol, etc.) are water-soluble triiodide benzene ring derivatives, whose molecular structure contains three iodine atoms and multiple hydroxyl groups, and have a large molecular volume and high rigidity.

[0048] Compared to water, contrast agents have the following significant physical properties: Viscosity: Pure water has a viscosity of approximately 0.7 mPa·s at 37°C, while commonly used iodine contrast agents in clinical settings have a viscosity of approximately 3.4-10.4 mPa·s at 37°C, with some high-concentration formulations reaching 26.6 mPa·s, approximately 5-15 times that of water. The high viscosity is fundamentally due to the large molecular structure of the triiodide benzene ring and the strong intermolecular interactions.

[0049] Density: Pure water has a density of 1.0 g / mL, while the density of iodine contrast agent is usually in the range of 1.27-1.43 g / mL, which is significantly higher than that of water. The high density is due to the high atomic weight of the three iodine atoms in the molecule.

[0050] Flowability: Due to its high viscosity and high density, the flowability of contrast agents in the same gap is much lower than that of water. The intermolecular friction is greater, and the resistance to be overcome during flow is higher.

[0051] For laminar flow within an annular gap, there is a linear positive correlation between pressure drop and fluid dynamic viscosity. Under the same gap size and flow velocity conditions, the higher the fluid viscosity, the greater the flow resistance. This means that when a high-viscosity contrast agent flows within an annular gap, the flow resistance per unit gap is much greater than that of water.

[0052] After experimentation, it was found that with pure water as the flow medium, a radial gap of approximately 0.01 mm is sufficient to generate sufficient flow resistance to form an effective anti-backflow barrier. This application sets the radial gap to 0.02-0.03 mm, which is compatible with the high viscosity characteristics of the contrast agent. Based on this, the anti-backflow gap 3 in this application works synergistically through the following multiple mechanisms: High flow resistance throttling mechanism: The flow resistance of the annular gap is inversely proportional to a high power of the gap size. When the gap size is reduced from that of a conventional coaxial system to 0.02-0.03 mm, the flow resistance increases by an order of magnitude. When high-pressure injection of contrast agent generates backflow pressure, the contrast agent attempts to escape proximally, but must pass through the extremely narrow anti-backflow gap 3. Due to the extremely high flow resistance, most of the backflow pressure is consumed in the anti-backflow gap 3, ultimately preventing backflow.

[0053] Static pressure support mechanism: Due to the extremely small radial clearance, the fluid in the annular space between the outer tube 2 and the inner tube is almost stationary or flows at a very low speed, and its pressure distribution is closer to static pressure. When the contrast agent attempts to flow back towards the proximal end, it needs to overcome the existing static pressure in the clearance. The nearly stationary fluid forms a fluid pad, creating static pressure support in the radial clearance to counteract the backflow driving force.

[0054] Jet confinement mechanism: After the contrast agent jet leaves the inner angiography catheter 1, when the distal end of the inner angiography catheter 1 is located proximal to the distal end of the outer cannula 2, the contrast agent is confined within the lumen of the outer cannula 2 until it reaches the distal opening of the outer cannula 2 before actually entering the blood vessel; or, when the distal end of the inner angiography catheter 1 is located distal to the distal end of the outer cannula 2, the contrast agent is released in the area near the distal end of the inner angiography catheter 1 and directly enters the blood vessel.

[0055] Because the distal end of the outer cannula 2 is anchored at the distal target location at the C4-C5 level of the vertebral artery, the jet direction is more precisely aligned with the target vessel, reducing the dissipation of jet momentum proximally and thus lowering the momentum source driving reflux. At the same injection pressure, more contrast agent momentum is used to fill the target vessel in the posterior circulation, rather than being wasted on reflux and proximal turbulence.

[0056] Density-inertia-assisted mechanism: The high density of the contrast agent gives it greater inertia in the gap. When a reverse pressure gradient occurs, a greater pressure difference is required to accelerate the flow of the contrast agent towards the proximal end, which enhances the stability of the barrier to some extent.

[0057] Whether through high flow resistance throttling mechanism, static pressure support mechanism or density inertia auxiliary mechanism, the radial gap in this application can couple to form a high-pressure injection liquid film seal without any filling components, thereby achieving the effect of preventing contrast agent reflux. Under the condition of no active balloon occlusion, it inhibits the reflux of contrast agent through the target blood vessel opening during high-pressure injection, improves distal imaging and reduces the amount of contrast agent used.

[0058] It should be noted that the anti-backflow gap 3 is not a completely sealed structure, but rather forms fluid resistance through a precise radial fit. This balances the advancement of the outer cannula 2 relative to the inner contrast catheter 1 with providing a backflow barrier for the contrast agent. It allows the outer cannula 2 to be pushed coaxially relative to the inner contrast catheter 1, while also forming a barrier to prevent proximal backflow during contrast agent injection.

[0059] Compared with existing balloon occlusion methods, this application does not require additional balloon inflation and deflation, making the operation simpler; compared with the Y-valve hemostasis method, this application directly acts on the distal catheter fitting relationship, and is more targeted at the reflux problem in posterior circulation angiography.

[0060] From the perspective of the structural composition of the internal angiography catheter 1, the internal angiography catheter 1 in this application can be a conventional 5F neuroangiography catheter, and the length of the internal angiography catheter 1 is 120-130cm to meet the requirements of a longer route via the radial approach.

[0061] The internal contrast catheter 1 includes a lumen for injecting contrast agent. The outer wall surface of the internal contrast catheter 1 is preferably smooth to form a precise radial fit with the inner wall of the outer cannula 2, while facilitating the axial movement of the outer cannula 2 relative to the internal contrast catheter 1.

[0062] Furthermore, the endovascular angiography catheter 1 comprises a proximal segment 11, a transition segment 12, and a distal end 13. The proximal segment 11 has a higher stiffness than the transition segment 12, and the transition segment 12 has a higher stiffness than the distal end 13. Through this multi-segment stiffness setting, the endovascular angiography catheter 1 can balance proximal support, mid-segment advancement, and distal flexibility. Specifically, the proximal segment 11 provides the support force required for advancement via the radial approach, the transition segment 12 achieves a smooth transition in stiffness, and the distal end 13 reduces irritation to the vertebral artery orifice wall.

[0063] In a preferred embodiment, the proximal segment 11 has a Shore hardness of 72-78D, the transition segment 12 has a Shore hardness of 58-63D, and the tip 13 has a Shore hardness of 25-33D or 80±10A. Compared with the existing conventional single-lumen angiography catheters with a uniform hardness of 60-70D throughout, the above hardness range allows for a more flexible tip, thereby reducing the incidence of vasospasm. Simultaneously, the higher proximal hardness facilitates torque and thrust transmission over long radial approaches, alleviating torque transmission hysteresis.

[0064] The tip 13 of the catheter body is shaped to fit the opening of the vertebral artery. Specifically, the tip 13 can be molded into common neuroangiography catheter tip shapes such as Simmons, Headhunter, or Ver. Through this molding, the internal angiography catheter 1 can more easily superselectively enter the opening of the vertebral artery and provide guidance for the subsequent coaxial advancement of the outer cannula 2.

[0065] In terms of structure, the outer cannula 2 is nested outside the inner angiography catheter 1 and can be coaxially advanced relative to the inner angiography catheter 1. The outer diameter of the outer cannula 2 is 5.5-6.5F, and its length is 105-115cm. The length of the inner angiography catheter 1 is greater than the length of the outer cannula 2, thereby enabling the construction of a superselective pathway, which facilitates the advancement of the outer cannula 2 relative to the stationary inner angiography catheter 1, and makes it easier for the operator to manipulate the inner angiography catheter 1. Preferably, the outer cannula 2 is 15-20cm shorter than the inner angiography catheter 1.

[0066] The outer sheath 2 includes a proximal support section 21, an intermediate transition section 22, and a distal soft section 23. The proximal support section 21 provides pushing support, the intermediate transition section 22 facilitates a transition in rigidity, and the distal soft section 23 allows for smooth passage through the vertebral artery opening and advancement along the vertebral artery. The distal soft section 23 may include a hydrophilic soft segment to reduce frictional resistance during pushing and improve passability.

[0067] A contrast-enhancing ring 24 is provided at the distal end of the outer cannula 2. The contrast-enhancing ring 24 is located at the distal soft segment 23, and a distance of 3-8 mm is maintained between the contrast-enhancing ring 24 and the distal opening of the distal soft segment 23. Through the contrast-enhancing ring 24, the surgeon can confirm under X-ray fluoroscopy whether the tip of the outer cannula 2 has reached the distal target position at the C4-C5 level of the vertebral artery. Maintaining a distance of 3-8 mm between the contrast-enhancing ring 24 and the distal opening facilitates more accurate determination of the distal position of the outer cannula 2 under fluoroscopy, while preventing the contrast-enhancing ring 24 from being too close to the opening and affecting the passage of the soft segment.

[0068] Furthermore, in this application, the hardness of the hydrophilic soft section of the outer sleeve 2 is Shore hardness less than or equal to 35D, or the hardness of the hydrophilic soft section is Shore hardness 80±10A, and the hardness of the proximal support section 21 is Shore hardness 72-78D.

[0069] By setting the contrast ring 24, the distal part of the outer tube 2 can form an ultra-soft hydrophilic section with an axial length of 3-8mm and a Shore hardness of ≤35D, or a Shore hardness of 80±10A. The hardness is more than two levels lower than the Shore hardness of the proximal support section 21-78D of the tube body. This allows the outer tube 2 to pass over the vertebral artery opening and enter the blood vessel with zero resistance, and penetrate to the distal target position at the C4-C5 level. This maximizes the imaging effect without causing spasm.

[0070] The proximal end of the internal angiography catheter 1 is connected to the internal angiography catheter seat 14, and the proximal end of the outer cannula 2 is connected to the outer cannula seat 25. The outer cannula seat 25 is nested in the distal side of the internal angiography catheter seat 14.

[0071] With this setup, the operator can operate the inner angiography catheter 1 and the outer cannula 2 separately. The inner angiography catheter seat 14 is used to connect the high-pressure injector, guidewire or other accessories, and the outer cannula seat 25 is used to push and pull the outer cannula 2.

[0072] The outer cannula seat 25 is nested on the distal side of the inner angiography catheter seat 14, which makes the overall structure more compact and facilitates one-handed or two-handed operation by the operator during the radial approach. At the same time, the relative positional relationship between the inner angiography catheter seat 14 and the outer cannula seat 25 is compatible with commonly used instruments such as Y valves, guidewires and high-pressure injectors for existing neuroangiography catheters, resulting in a lower clinical learning curve.

[0073] During contrast agent injection, the engagement angle between the distal end of the outer cannula 2 and the distal end of the inner angiography catheter 1 is configured in one specific embodiment as follows: after the outer cannula 2 is advanced into position, the distal end of the inner angiography catheter 1 extends distally outward relative to the distal end of the outer cannula 2, or the distal end of the outer cannula 2 extends distally outward relative to the distal end of the inner angiography catheter 1. The distance between the distal end of the inner angiography catheter 1 and the distal end of the outer cannula 2 does not exceed 5 mm.

[0074] In another specific embodiment, after the outer tube 2 is pushed into place, it can also be configured such that the distal end of the outer tube 2 is flush with the distal end of the internal angiography catheter 1.

[0075] The above-described embodiments provide various distal end fitting methods. In actual angiography, the operator can choose different fitting methods based on the vertebral artery opening morphology, target angiography location, and contrast agent injection method. Regardless of the method used, the anti-reflux gap 3 between the outer cannula 2 and the inner angiography catheter 1 can effectively prevent proximal reflux of the contrast agent.

[0076] Meanwhile, controlling the distance between the distal ends of the two tubes to no more than 5mm helps to avoid affecting the anti-backflow effect due to excessive tube spacing, and also facilitates the smooth injection of contrast agent from the distal end of the internal contrast catheter 1 into the target area.

[0077] At the same time, regardless of the method of combination, provided that the outer cannula 2 is anchored at the distal target position at the C4-C5 level of the vertebral artery, the contrast agent can be directly applied to the target vessel in the posterior circulation, forming a precise and effective imaging basis, which makes the doctor's judgment of the lesion more accurate.

[0078] This application also provides an angiography catheter system for use in transradial posterior circulation angiography. The angiography catheter system includes a radial artery sheath and the nested angiography catheter described in any of the preceding claims. The inner angiography catheter 1 is advanced through the radial artery sheath to the distal end of the vertebral artery, and the outer cannula 2 is coaxially advanced along the inner angiography catheter 1 to a distal target position at the C4-C5 level of the vertebral artery.

[0079] In practical use, the following steps may be included: Step S1: Establish a transradial approach, puncture the radial artery using the standard Seldinger technique, and insert a 6F transradial sheath.

[0080] Step S2: Insert the angiography catheter 1, insert the 5F neuroangiography catheter through the radial artery sheath, adjust its shape under X-ray fluoroscopy, superselect it to the opening of the vertebral artery and push it to the distal end of the vertebral artery.

[0081] Step S3: Push the outer cannula 2 and insert it coaxially along the inner angiography catheter 1. The ultra-soft hydrophilic segment at the tip of the outer cannula 2 smoothly passes through the opening of the vertebral artery and is advanced along the vertebral artery to the distal target position at the C4-C5 level.

[0082] Step S4: Position Confirmation. Observe the position of the tip of the outer sheath 2 using fluoroscopy, and use the pre-set contrast ring 24 at the distal end of the 3-8mm soft segment at the tip to confirm that the outer sheath 2 has reached the C4-C5 level of the vertebral artery.

[0083] Step S5: Inject contrast agent. Fix the position of the outer cannula 2, connect the high-pressure injector through the inner angiography catheter 1, and inject the contrast agent for posterior circulation angiography. The coaxial nesting structure of the outer cannula 2 and the inner angiography catheter 1, along with the precise radial gap, forms a barrier structure, reducing the probability of contrast agent reflux through the vertebral artery opening.

[0084] Step S6: Catheter Removal. After the angiography is completed, first remove the outer cannula 2, then remove the inner angiography catheter 1 to complete the procedure.

[0085] The above-mentioned angiography catheter system combines the specific application scenarios of radial approach and posterior circulation angiography. Compared with the general 5F single-lumen nerve angiography catheter, this application enables the outer cannula 2 to reach the C4-C5 level of the vertebral artery through the coaxial nesting of the outer cannula 2 and the inner angiography catheter 1, forming an angiography position closer to the target area and an anti-reflux barrier.

[0086] Compared to existing coaxial delivery systems for therapeutic use, this application is not primarily intended for delivering thrombectomy, embolization, or drug delivery devices, but rather for structural optimization to address the needs of contrast agent anti-backflow, distal imaging optimization, and transradial approach delivery.

[0087] From a comprehensive performance perspective, this application can reduce the contrast agent reflux rate, reduce the total amount of contrast agent used, shorten the operation time, and is compatible with existing surgeon operating habits.

[0088] In summary, this application, through the nested coaxial structure of the inner angiography catheter 1 and the outer cannula 2, combined with the anti-backflow gap 3 between the outer cannula 2 and the inner angiography catheter 1, can achieve a synergistic technical effect in addressing multiple technical issues in the transradial approach post-circuit angiography scenario.

[0089] Firstly, regarding anti-reflux, this application utilizes a precise radial fit between the outer cannula 2 and the inner angiography catheter 1 to form a fluid barrier during contrast agent injection. This prevents the contrast agent from flowing back in large quantities from the distal end to the proximal end of the vertebral artery opening, thereby improving the visualization clarity of distal basilar artery, posterior cerebral artery, and other posterior circulation vessels. This anti-reflux effect is not simply achieved through size reduction, but rather by combining the high viscosity and high density properties of clinical contrast agents, achieving a balance between flow resistance and injection smoothness through a gap range of 0.02-0.03 mm.

[0090] Secondly, in terms of reducing contrast agent usage, the total amount of contrast agent required to achieve the same distal imaging clarity is reduced due to the decreased reflux rate. This is particularly beneficial for special patient groups such as those with renal insufficiency and the elderly, potentially reducing the risk of contrast-induced nephropathy.

[0091] Furthermore, in terms of reducing vasospasm, the endovascular catheter 1 can adopt a multi-segment rigidity structure with a rigid proximal end, a moderate transition segment 12, and a soft tip. This avoids the continuous stimulation of the vertebral artery orifice wall by the 60-70D rigid segment at the tip of a conventional catheter, thereby reducing the vasospasm induction rate and minimizing false stenosis artifacts.

[0092] In addition, in terms of operational compatibility, the internal angiography catheter 1 can use a commercially available general-purpose 5F neuroangiography catheter, and the outer cannula 2 follows the existing guiding catheter push operation logic. The high-pressure injector, guidewire, Y valve and other instruments are fully compatible, with a clinical learning curve of almost zero, and no need for retraining or replacement of the entire set of instruments.

[0093] Finally, in terms of surgical efficiency, the outer cannula 2 is directly anchored to the distal C4-C5 position of the vertebral artery, resulting in a shorter contrast agent injection path, improved imaging clarity, and a simultaneous reduction in X-ray exposure time and contrast agent dosage, thereby shortening the surgical time.

[0094] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0095] 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 nested angiography catheter, characterized in that, include: An internal contrast catheter and an outer cannula, wherein the internal contrast catheter is used to superselectively enter the vertebral artery orifice via a radial approach and push it to the distal end of the vertebral artery, and the internal contrast catheter includes a catheter lumen for injecting contrast agent; The outer cannula is nested outside the inner angiography catheter and can be pushed coaxially relative to the inner angiography catheter. The outer cannula can be advanced through the vertebral artery opening and reach the distal target position at the C4-C5 level of the vertebral artery. The length of the inner contrast catheter is greater than the length of the outer cannula. An anti-backflow gap is formed between the outer cannula and the inner contrast catheter. The anti-backflow gap is configured to form a fluid barrier structure that prevents the contrast agent from flowing back to the proximal end when the contrast agent is injected.

2. The nested angiography catheter according to claim 1, characterized in that, The anti-backflow gap is located between the outer wall of the inner angiography catheter and the inner wall of the outer sheath, including a radial fitting gap between the inner angiography catheter and the outer sheath, the radial dimension of which is 0.02-0.03 mm.

3. The nested angiography catheter according to claim 1, characterized in that, The intraneurography catheter includes a 5F outer diameter neuro-internal angiography catheter with a length of 120-130cm; The outer diameter of the outer sleeve is 5.5-6.5F, and the length is 105-115cm; The radial gap between the inner diameter of the outer sheath and the outer diameter of the internal angiography catheter is 0.02-0.03 mm.

4. The nested angiography catheter according to claim 1, characterized in that, The internal angiography catheter comprises, in sequence, a proximal segment, a transition segment, and a tube head; The hardness of the proximal section is greater than that of the transition section, and the hardness of the transition section is greater than that of the tube head. The tube head is shaped to fit the opening of the vertebral artery.

5. The nested angiography catheter according to claim 4, characterized in that, The internal angiography catheter includes a smooth outer wall surface; The hardness of the proximal section is Shore hardness 72-78D, the hardness of the transition section is Shore hardness 58-63D, and the hardness of the tube head is Shore hardness 25-33D or 80±10A.

6. The nested angiography catheter according to claim 1, characterized in that, The outer sheath includes a proximal support section, an intermediate transition section, and a distal flexible section; The distal soft segment includes a hydrophilic soft segment; The outer tube is provided with a developing ring at its distal end. The developing ring is located in the distal flexible section, and the developing ring is spaced 3-8 mm away from the distal opening of the distal flexible section. The hydrophilic soft segment has a Shore hardness of less than or equal to 35D, or the hydrophilic soft segment has a Shore hardness of 80±10A, and the proximal support segment has a Shore hardness of 72-78D.

7. The nested angiography catheter according to claim 1, characterized in that, The proximal end of the internal angiography catheter is connected to an internal angiography catheter seat, and the proximal end of the outer cannula is connected to an outer cannula seat. The outer cannula seat is nested on the distal side of the internal angiography catheter seat.

8. The nested angiography catheter according to claim 7, characterized in that, After the outer tube is pushed into place, it is configured as follows: The distal end of the internal angiography catheter extends outward relative to the distal end of the outer cannula, or the distal end of the outer cannula extends outward relative to the distal end of the internal angiography catheter. The distance between the distal end of the internal angiography catheter and the distal end of the outer cannula does not exceed 5 mm.

9. The nested angiography catheter according to claim 1, characterized in that, After the outer tube is pushed into place, it can also be configured such that the distal end of the outer tube is flush with the distal end of the internal angiography catheter.

10. A contrast catheter system for use in transradial posterior circulation contrast angiography, characterized in that, The method includes a radial artery sheath and a nested angiography catheter according to any one of claims 1-9, wherein the inner angiography catheter is advanced through the radial artery sheath to the distal end of the vertebral artery, and the outer cannula is coaxially advanced along the inner angiography catheter to a distal target position at the C4-C5 level of the vertebral artery.

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