Diameter-variable interventional micro-catheter

Abstract

The invention provides a variable-diameter interventional micro-catheter. The variable-diameter interventional micro-catheter comprises an outer catheter and a variable-diameter assembly arranged in the outer catheter, the variable-diameter assembly comprises a plurality of variable-diameter units distributed in the axial direction of the outer guide pipe, and each variable-diameter unit is configured to be capable of expanding or contracting according to the pressure change of a medium in the variable-diameter unit so as to adjust the radial size of the outer guide pipe in a segmented mode. According to the variable-diameter interventional micro-catheter, segmented diameter changing is achieved through the multiple diameter changing units based on medium pressure changes, the precise local diameter changing capacity is achieved, the micro-catheter can dynamically adapt to pipe diameter changes of different sections in a cerebrovascular complex channel, and especially when the micro-catheter passes through a narrow blood vessel, the diameter of the micro-catheter can be changed. The outer diameter of the target section can be adjusted instead of overall reducing so that smooth passing can be achieved, and therefore the risk of vasospasm or plaque disengagement caused by forced passing is avoided.

Description

Technical Field

[0001] This invention relates to the field of microcatheter technology, and more particularly to a variable-diameter interventional microcatheter. Background Technology

[0002] Interventional cerebrovascular therapy relies on the precise navigation of microcatheters in the complex intracranial vascular network. Intracranial cerebrovascular vessels have anatomical characteristics such as "small diameter (only 1-2 mm at the thinnest point), tortuous course (such as the "S" shape of the M2-M4 segment of the middle cerebral artery), and dense branching (such as as many as 10-15 branches around the circle of Willis)".

[0003] The aforementioned traditional interventional microcatheters have the following defects, making it difficult to meet the treatment needs of complex pathways: poor diameter adaptability and limited passage. Traditional microcatheters are mostly fixed diameter or simple stepped variable diameter structures, which cannot dynamically adapt to the diameter changes of cerebral blood vessels.

[0004] When there is a narrow segment in the cerebral blood vessels (such as 50% to 70% narrowing caused by atherosclerosis), microcatheters with a fixed diameter (such as 1.5 mm outer diameter) are difficult to pass through the narrowed area. Forcibly pushing them can easily compress the vascular endothelium, causing vasospasm (with an incidence rate as high as 25%) or plaque detachment, leading to cerebral embolism.

[0005] Simple stepped diameter-changing structures have crude diameter-changing power control. Some hydraulically driven diameter-changing microcatheters use a single gas / liquid channel to control the overall diameter change, which cannot achieve "local precise diameter change" (such as adjusting only the outer diameter of the distal 1 / 4 of the catheter). At branch vessels, the overall diameter change can easily cause adjacent vessels to be compressed.

[0006] Therefore, in order to solve the above problems, the present invention proposes a variable diameter interventional microcatheter with variable diameter function and adjustable outer diameter in sections. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention provides a variable diameter interventional microcatheter.

[0008] According to one objective of the present invention, the present invention provides a variable diameter interventional microcatheter, comprising:

[0009] An external conduit, and a variable diameter assembly disposed inside the external conduit;

[0010] The variable diameter assembly includes multiple variable diameter units distributed along the axial direction of the outer conduit. Each variable diameter unit is configured to expand or contract according to pressure changes of its internal medium to adjust the radial dimension of the outer conduit in segments.

[0011] Preferably, the variable diameter assembly includes:

[0012] Multiple gas delivery pipes are disposed inside the outer conduit. The gas delivery pipes extend along their axial direction. The ends of the extended gas delivery pipes correspond one-to-one with the variable diameter unit and are interconnected. The head end of the extended gas delivery pipes is configured to fill or discharge gas.

[0013] A control valve is provided at the head end of each of the gas pipelines, and the control valve is configured to control the pressure of the medium transported by the gas pipeline.

[0014] Preferably, each of the variable diameter units includes:

[0015] A connecting pipe is disposed circumferentially on the outside of the gas transmission pipe along the outer conduit, and the connecting pipe is connected to the gas transmission pipe;

[0016] An extension tube is provided on the side of the connecting tube facing the inner wall of the gas transmission pipe, which communicates with the connecting tube. The extension tube can expand or contract according to the pressure changes of the internal medium.

[0017] Preferably, in each of the variable diameter units, there are multiple connecting pipes, which are arranged sequentially at intervals along the axial direction of the outer conduit; and there are multiple extension pipes, which are arranged sequentially at intervals along the circumference of the connecting pipes.

[0018] Preferably, the gas delivery pipes are arranged sequentially at intervals along the circumference of the outer conduit, the connecting pipes are arranged in a ring shape, and the connecting pipes penetrate the outer surface of the gas delivery pipes. In the diameter-changing units adjacent to each other in the axial direction of the outer conduit, the connection positions of the connecting pipes and the gas delivery pipes are arranged sequentially at intervals along the circumference of the connecting pipes.

[0019] Preferably, the size of the extension tube gradually increases away from the connecting tube; the outer wall of the extension tube does not extend beyond the outer wall of the outer conduit.

[0020] Preferably, the variable diameter assembly further includes:

[0021] A gas delivery tube is provided, one end of which is connected to the head end of the gas supply tube extension. The control valve is installed on the gas delivery tube. The other end of the gas delivery tube is connected to a gas chamber. An air hole and a pressure sensor are installed on the side of the gas chamber away from the external conduit.

[0022] Preferably, the air chamber is annular, with a drug delivery tube sleeved on its inner ring. The other end of the drug delivery tube is connected to an inner conduit, which passes through the inner side of the outer conduit and has a pre-set delivery channel inside.

[0023] Both the gas delivery pipe and the variable diameter unit are located between the outer conduit and the inner conduit.

[0024] Preferably, a support structure is provided between the inner conduit and the outer conduit. The support structure consists of a plurality of spring coils arranged sequentially along the axial direction of the inner conduit and embedded between the inner conduit and the outer conduit. The spring coils are spring coils with shape memory characteristics.

[0025] Preferably, the gas supply pipe is divided into gas supply pipe one, gas supply pipe two, gas supply pipe three and gas supply pipe four arranged sequentially in the circumferential direction of the outer conduit.

[0026] The length of the gas supply pipe is equal to the length of the outer conduit and the ends are flush. Gas supply pipe one, gas supply pipe two and gas supply pipe three are provided with a sealing part, wherein the sealing part on gas supply pipe one is located at 1 / 4 of its total length, the sealing part on gas supply pipe two is located at 1 / 2 of its total length, the sealing part on gas supply pipe three is located at 3 / 4 of its total length, and the end of gas supply pipe four is connected to the connecting pipe.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This variable-diameter interventional microcatheter achieves segmented diameter changes based on media pressure variations through multiple variable-diameter units, enabling precise local diameter changes. This allows the microcatheter to dynamically adapt to diameter changes in different segments of complex cerebrovascular pathways. Especially when passing through narrowed vessels, it can adjust only the outer diameter of the target segment rather than changing the overall diameter to ensure smooth passage, thus avoiding the risk of vasospasm or plaque dislodgement caused by forced passage. At the same time, this segmented control enhances the catheter's compliance in tortuous vessels, effectively solving the problems of poor passage and low success rate caused by fixed or coarse diameter changes in traditional microcatheters.

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an interventional microcatheter with variable diameter as described in this invention;

[0031] Figure 2 This is a schematic diagram of the external catheter in a variable-diameter interventional microcatheter according to the present invention;

[0032] Figure 3 This is a schematic diagram of a drug delivery device in a variable-diameter interventional microcatheter according to the present invention;

[0033] Figure 4 This is a schematic diagram of the interior of the outer catheter in a variable-diameter interventional microcatheter according to the present invention;

[0034] Figure 5 This is a schematic diagram showing the connection state of the gas delivery tube and connecting tube in a variable diameter interventional microcatheter according to the present invention;

[0035] Figure 6 This is a schematic diagram of the connecting tube in a variable-diameter interventional microcatheter according to the present invention;

[0036] Figure 7 This is a schematic diagram showing the connection state between the inner catheter and the spring coil in a variable-diameter interventional microcatheter according to the present invention.

[0037] In the diagram: 101, external conduit; 102, gas delivery tube; 103, connecting tube; 104, extension tube; 105, gas guide tube; 106, three-way valve; 107, gas chamber; 108, air hole; 109, drug delivery tube; 110, internal conduit; 111, spring coil; 112, connection port. Detailed Implementation

[0038] The following description is intended to provide a detailed account of the invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0039] This invention provides a technical solution: a variable-diameter interventional microcatheter that can be used for complex cerebrovascular access, and is suitable for precise navigation and treatment of complex cerebrovascular access in neurointerventional surgery, such as intracranial arterial tortuosity, vascular stenosis, and densely branched areas. It can adapt to cerebrovascular vessels of different diameters by dynamically adjusting the outer diameter of the catheter, and at the same time realize the synergistic function of drug delivery and gas-assisted diameter adjustment, thereby improving the safety and effectiveness of interventional treatment of complex cerebrovascular diseases, such as intracranial aneurysms and arteriovenous malformations.

[0040] See Figure 1-2 The interventional microcatheter includes:

[0041] An external conduit 101, and a variable diameter assembly disposed inside the external conduit 101;

[0042] The variable diameter assembly includes multiple variable diameter units distributed along the axial direction of the outer conduit 101. Each variable diameter unit is configured to expand or contract according to pressure changes of its internal medium to adjust the radial dimension of the outer conduit 101 in segments.

[0043] A variable diameter unit is provided inside the outer conduit 101 and distributed along the axial direction of the outer conduit 101. During use, the internal medium pressure of the variable diameter unit in each section of the outer conduit 101 can be adjusted to achieve segmented precise diameter change.

[0044] To address the problem of difficulty in adapting to multi-branched vessels with existing variable-diameter microcatheters, specifically in densely branched areas such as the Willis ring, where the vessel diameter drops sharply from 2-3 mm to less than 1 mm, the diameter variation range of traditional microcatheters is limited (usually only 0.5-1 mm), making it impossible to quickly adapt to the diameter change, and it is easy to mistakenly enter non-target branches, thus prolonging the operation time (an average extension of 30-60 minutes).

[0045] Preferably, the diameter variation range of the variable diameter unit is 0.8~1.8mm, which can adapt to the 1~3mm diameter change of cerebral blood vessels, improve the success rate of passing through narrow blood vessels, and thus solve the problems of poor diameter adaptability and limited passage of traditional microcatheters, and avoid vasospasm caused when forcibly passing through narrow segments.

[0046] See Figure 4 The variable diameter assembly includes:

[0047] Multiple gas delivery pipes 102 are disposed inside the outer conduit 101. The gas delivery pipes 102 extend along its axial direction. The extended ends of the gas delivery pipes 102 correspond one-to-one with the variable diameter unit and are interconnected. The extended head end of the gas delivery pipes 102 is configured to fill or discharge gas.

[0048] A control valve is provided at the head end of each of the gas pipelines 102, and the control valve is configured to control the pressure of the medium conveyed by the gas pipeline 102.

[0049] In use, the gas flow of each gas delivery tube 102 can be independently controlled by the control valve, thereby controlling the medium delivered by the gas delivery tube 102 and the pressure of the medium delivered into the variable diameter unit by the gas delivery tube 102. According to the inner diameter of the inserted blood vessel, the expansion or contraction size of each variable diameter unit can be adjusted, thereby achieving localized and precise diameter change of some sections of the external catheter 101. This avoids the problems of coarse control of the variable diameter power and pressure on adjacent blood vessels caused by overall diameter change, and overcomes the defect that traditional hydraulic / pneumatic driven microcatheters cannot achieve localized diameter change using a single channel.

[0050] See Figure 4 , Figure 5 and Figure 6 Each of the aforementioned variable diameter units includes:

[0051] A connecting pipe 103 is disposed circumferentially on the outside of the gas transmission pipe 102 along the outer conduit 101, and the connecting pipe 103 is connected to the gas transmission pipe 102.

[0052] An extension tube 104 is provided on the side of the connecting tube 103 facing the inner wall of the gas supply tube 102, communicating with the connecting tube 103. The extension tube 104 can expand or contract according to the pressure change of the internal medium. The extension tube 104 acts as an actuator, and its expansion and contraction directly adjust the outer diameter of the conduit. Specifically, when a medium (such as gas) is introduced into the extension tube 104 through the gas supply tube 102, the extension tube 104 expands, increasing the radial dimension of that section of the outer conduit 101; conversely, when the medium is discharged, the extension tube 104 contracts, decreasing its radial dimension. The extension tube 104 is made of an elastic material and can be equipped with internal elastic support ribs to ensure that the tube wall does not collapse after diameter change, solving the problem of weak tube wall support after diameter change.

[0053] Furthermore, in each of the diameter-changing units, there are multiple connecting pipes 103, which are arranged sequentially at intervals along the axial direction of the outer conduit 101; and multiple extension pipes 104, which are arranged sequentially at intervals along the circumference of the connecting pipes 103. This ensures that the diameter-changing unit on each section of the outer conduit 101 can adjust the radial dimension of the outer conduit 101 relatively uniformly when adjusting the radial dimension of the outer conduit 101. Specifically, the extension pipes 104 can uniformly compress the outer conduit 101 circumferentially during expansion and contraction, thereby achieving the diameter-changing effect.

[0054] Further, see Figure 5 The gas delivery pipes 102 are arranged sequentially at intervals along the circumference of the outer conduit 101. The connecting pipes 103 are arranged in a ring shape and penetrate the outer surface of the gas delivery pipes 102. In the diameter-changing units adjacent to the outer conduit 101 in the axial direction, the connection positions of the connecting pipes 103 and the gas delivery pipes 102 are arranged sequentially at intervals along the circumference of the connecting pipes 103. This ensures that after the gas delivery pipes 102 and the connecting pipes 103 are installed, the connecting pipes 103 can support the gas delivery pipes 102 to a certain extent, ensuring that they have a relatively stable installation position within the outer conduit 101. Specifically, the side wall of the connecting pipe 103 has a connection port 112 that connects to the gas delivery pipes 102. The connection ports 112 adjacent to the diameter-changing units in the axial direction of the outer conduit 101 are arranged at equal intervals along the circumference of the connecting pipes 103. That is, each set of connection ports 112 corresponds one-to-one with the connection pipe 103. When the connection port 112 is located at the top of the connection pipe 103, the connection port 112 is connected to the first connection pipe 103, and so on.

[0055] Further, see Figure 4 and 6The size of the extension tube 104 gradually increases away from the connecting tube 103, that is, the extension tube 104 contracts into a conical diameter shape from the end away from the connecting tube 103 to the other end. By limiting the size of the extension tube 104, and ensuring its wall thickness is uniform when the medium is poured in, the end away from the connecting tube 103 can deform before other parts, thereby improving its efficiency in adjusting the radial size of the external catheter 101. In addition, the outer wall of the extension tube 104 does not extend beyond the outer wall of the external catheter 101 to avoid the protruding part scratching the blood vessel. Preferably, the outer wall of the extension tube 104 is flush with the outer wall of the external catheter 101. It should be noted that the outer wall here specifically refers to the wall surface of the extension tube 104 and the external catheter 101 on the radially outer side of the external catheter 101.

[0056] As a preferred embodiment, see [link to previous document]. Figure 4 The gas delivery tubes 102 are four in number, evenly distributed circumferentially along the outer conduit 101. To achieve precise segmented control, the gas delivery tubes 102 adopt a segmented sealed design. The sealed portion of the first gas delivery tube 102 is located at 1 / 4 of its total length, the second at 1 / 2, the third at 3 / 4, and the fourth is fully open. By independently controlling the pressure of different gas delivery tubes 102, independent diameter changes can be achieved in different sections of the conduit, such as the distal, middle, and proximal ends.

[0057] Specifically, the gas supply pipe 102 is divided into gas supply pipe one, gas supply pipe two, gas supply pipe three and gas supply pipe four arranged sequentially in the circumferential direction of the outer conduit 101;

[0058] The length of the gas inlet tube 102 is equal to the length of the external catheter 101, and their ends are flush. Gas inlet tube one, gas inlet tube two, and gas inlet tube three are equipped with sealing sections. The sealing section on gas inlet tube one is located at 1 / 4 of its total length, the sealing section on gas inlet tube two is located at 1 / 2 of its total length, and the sealing section on gas inlet tube three is located at 3 / 4 of its total length. The end of gas inlet tube four connects to the connecting tube 103. The segmented, sealed gas inlet tube 102 achieves precise four-segment diameter change. The different sealing section positions of the gas inlet tube 102 precisely control the axial segment of the diameter change, achieving local diameter change capability. This reduces operation time in densely branched areas such as the circle of Willis, avoids accidental entry into non-target branches, and this design achieves precise segmented diameter change, improving the success rate of navigating complex cerebrovascular pathways.

[0059] To address the lack of real-time status feedback in existing variable-diameter microcatheters, specifically, key parameters such as catheter outer diameter and intravascular pressure cannot be monitored during the diameter-changing process. Operators can only make indirect judgments through imaging, which can easily lead to vascular damage due to excessive diameter change or affect the passability due to insufficient diameter change. Furthermore, existing variable-diameter microcatheters have cumbersome control methods that require extensive operator experience. Specifically, the diameter-changing operation involves multiple steps, with some mechanically controlled variable-diameter microcatheters requiring adjustments via multiple sets of knobs, resulting in 5-8 steps. When rapid passage through narrow vessels is required, delays can easily lead to vasospasm. The lack of visual guidance means that matching the diameter-changing range with the vessel diameter relies on the operator's experience and judgment, without clear scales or feedback. Novice operators are prone to "over-diametering" or "under-diametering," resulting in a surgical complication rate 2-3 times higher than experienced operators.

[0060] See Figures 2 to 4 The variable diameter assembly further includes:

[0061] A gas guide pipe 105 is provided, one end of which is connected to the extended end of the gas delivery pipe 102. A control valve is installed on the gas guide pipe 105. The other end of the gas guide pipe 105 is connected to a gas chamber 107. An air vent 108 and a pressure sensor are installed on the side of the gas chamber 107 away from the outer conduit 101. The pressure sensor can monitor the pressure inside the gas chamber 107 in real time, indirectly providing feedback on the gas pressure in the gas delivery pipe 102, thus achieving real-time status feedback and solving the problem of excessive or insufficient diameter changes due to a lack of real-time status feedback. The three-way valve 106 has three states: "inlet," "outlet," and "closed." It can independently control each gas delivery tube 102, providing clear operation and solving the problems of multiple steps and steep learning curves in diameter-changing operations. Preferably, the three-way valve 106 is equipped with a control knob: clockwise rotation is for "inlet," used to control the expansion of the extension tube 104, increasing the outer diameter of the catheter; counterclockwise rotation is for "outlet," used to control the contraction of the extension tube 104, decreasing the outer diameter of the catheter. The knob has a scale corresponding to 0-5 levels, with each level corresponding to an outer diameter change of 0-0.8 mm. The conical diameter-changing design of the extension tube 104 and the scaled control knob improve the accuracy of outer diameter adjustment, reduce the error in matching the blood vessel diameter, and lower the rate of blood vessel damage.

[0062] To address the issue that existing variable-diameter microcatheters only focus on "diameter adjustment" and do not integrate treatment-related functions, leading to complex surgical procedures, specifically, existing variable-diameter microcatheters do not have an independent drug delivery channel. When treating intracranial aneurysms or vascular malformations, additional microcatheters need to be inserted to deliver embolic agents or chemotherapy drugs. The parallel use of multiple catheters increases the risk of vascular blockage, and drugs are prone to leakage in non-target areas (leakage rate 10% to 15%).

[0063] See Figure 3 and 4The device also integrates drug delivery functionality. The gas chamber 107 is annular, with a drug delivery tube 109 fitted inside. The other end of the drug delivery tube 109 is connected to an inner catheter 110, which passes inside the outer catheter 101 and has a pre-set delivery channel. The gas delivery tube 102 and the variable diameter unit are both located between the outer catheter 101 and the inner catheter 110. In use, the device and medication can be delivered using the drug delivery tube 109 and the inner catheter 110, achieving a synergistic function of drug delivery and gas-assisted variable diameter. This eliminates the need for additional microcatheters, solving the problems of single-function limitations and lack of synergistic treatment capabilities, and reducing the risks of vascular occlusion and drug leakage associated with multiple catheters operating in parallel.

[0064] Preferably, the inner wall of the infusion tube 109 is coated with an anti-adsorption coating to reduce drug adsorption on the tube wall and ensure accurate drug dosage.

[0065] To address the issue of weak wall support in existing variable-diameter microcatheters after diameter change, specifically, the wall thickness of the elastic variable-diameter microcatheter in the constricted state is only 0.1-0.2 mm, with insufficient radial compressive strength (≤0.5 MPa). It is easily squeezed and collapsed by intravascular pressure, leading to lumen blockage and affecting device / drug delivery.

[0066] See Figure 7 To enhance the overall structural stability of the catheter, a support structure is provided between the inner catheter 110 and the outer catheter 101. This support structure consists of several spring coils 111, arranged sequentially along the axial direction of the inner catheter 110 and embedded between them. The spring coils 111 possess shape memory properties. During use, the shape memory properties of the spring coils 111 provide stable support within the body. Optionally, the spring coils 111 have a recovery temperature of 37°C, maintaining the axial stability of the inner catheter 110 within the body, preventing the catheter from kinking in tortuous blood vessels. Simultaneously, they enhance the support between the inner catheter 110 and the outer catheter 101, reducing lumen deformation during diameter changes and addressing the issue of insufficient structural stability. The spring coils 111 also enhance the radial compressive strength of the catheter (>0.5 MPa), preventing collapse due to intravascular pressure and subsequent lumen blockage.

[0067] To address the issue of easy breakage at the connection points of existing variable-diameter microcatheters, specifically, the connection points of multi-segment variable-diameter microcatheters use a simple adhesive bonding process. After repeated bending in tortuous blood vessels, the breakage rate at the connection points is as high as 8%, and broken catheter fragments may cause serious complications such as vascular embolism. Furthermore, in this variable-diameter microcatheter, the connection between the connecting tube 103 and the gas delivery tube 102 is made using a laser welding process; the two ends of the spring coil 111 are fixed to the inner catheter 110 by laser welding.

[0068] To address the biocompatibility concerns of existing variable-diameter microcatheters, specifically, some variable-diameter microcatheters use elastic materials (such as ordinary polyurethane) that, upon prolonged contact with blood in the body, can easily induce platelet adhesion (thrombosis incidence rate of 12%) or release trace amounts of harmful substances, leading to vascular inflammatory reactions. Furthermore, in this variable-diameter microcatheter, the outer catheter 101 is made of medical-grade polyimide-polyurethane composite material; the inner catheter 110 is made of highly flexible medical-grade nylon; the gas delivery tube 102 is made of medical-grade polyetheretherketone (PEEK); the connecting tube 103 is made of medical-grade stainless steel; the extension tube 104 is made of medical-grade elastic silicone; the gas delivery tube 105 is made of medical-grade PVC; the air chamber is made of medical-grade ABS; the drug delivery tube 109 is made of medical-grade fluoropolymer; and the spring coil 111 is made of medical-grade nickel-titanium alloy.

[0069] The present invention provides the following specific embodiment, in which each component of the variable diameter interventional microcatheter is described in detail.

[0070] External catheter 101: Made of medical-grade polyimide-polyurethane composite material, it is a long and thin tube with four evenly distributed "gas delivery tube 102 mounting grooves" on the tube wall for embedding the gas delivery tube 102; the inner wall of the external catheter 101 is coated with a super-slippery PTFE coating to reduce the relative friction between the inner catheter 110 and the external catheter 101.

[0071] Inner catheter 110: Made of highly flexible medical nylon, it is coaxially positioned inside the outer catheter 101 and used to deliver embolic agents, stents and other therapeutic devices; the outer surface of the inner catheter 110 has an axially formed "spring coil 111 fixing groove" to ensure the stable fixation of the spring coil 111;

[0072] The catheter is segmented: both the outer catheter 101 and the inner catheter 110 are divided into 4 segments along their length, corresponding to the sealing positions of the gas delivery tube 102, to achieve "segmented independent diameter change" - the proximal end of the first segment corresponds to the sealing point of 1 / 4 length of the gas delivery tube 102, the second segment corresponds to the sealing point of 1 / 2 length, the third segment corresponds to the sealing point of 3 / 4 length, and the distal end of the fourth segment is open for the entire length, to meet the diameter change requirements of different parts.

[0073] Gas delivery tubes 102: There are 4 tubes, each embedded in the mounting groove of the external catheter 101. They are made of medical-grade polyetheretherketone (PEEK) material, which has the characteristics of high temperature resistance and high pressure resistance. Each gas delivery tube 102 is a "unidirectional sealed structure". The sealed position of the first gas delivery tube 102 is located at 1 / 4 of the total length, the second at 1 / 2, the third at 3 / 4, and the fourth is completely open without sealing. Local diameter change control is achieved through "segmented sealing".

[0074] Connecting tube 103: Each set of gas supply tubes 102 corresponds to 4 sets of connecting tubes 103, which are made of medical stainless steel and are connected to the outer surface of the gas supply tube 102. The connection between the connecting tube 103 and the gas supply tube 102 is made of laser welding to avoid gas leakage. A "one-way connection port 112" is opened on the inner wall of the connecting tube 103. The connection port 112 is connected to the extension tube 104, and each set of connection ports 112 corresponds to the connecting tube 103 one by one. When the connection port 112 is located at the top of the inner wall of the connecting tube 103, it is only connected to the first gas supply tube 102. As the connecting tube 103 is rotated, it can be switched to the corresponding gas supply tube 102 to realize the selection of variable diameter section.

[0075] Extension tube 104: Communicates with the outer surface of connecting tube 103, and is made of medical elastic silicone material. It contracts from the end away from connecting tube 103 to the other end in a "conical diameter change shape". The outer wall of extension tube 104 is flush with the outer wall of external catheter 101 to avoid the protruding part scratching blood vessels. The extension tube 104 is equipped with "elastic support ribs" to ensure that the tube wall does not collapse after the diameter change.

[0076] The gas delivery tube 105 is connected at one end to the gas delivery tube 102 away from the sealed end, and at the other end to the gas chamber 107. It is made of medical-grade PVC material and a "three-way valve 106" (medical-grade polycarbonate material) is installed on the outer surface. The three-way valve 106 has three states: "inlet", "outlet", and "closed". It can independently control the gas flow of each gas delivery tube 102 to achieve precise diameter control.

[0077] Air chamber 107: It has a ring-shaped structure and is made of medical ABS material. The inner ring is connected to the drug delivery tube 109, and the outer ring is connected to four air delivery tubes 105. The upper surface of the air chamber 107 has "air holes 108" and "pressure sensors" are installed at the air holes 108 to monitor the pressure inside the air chamber 107 in real time and indirectly provide feedback on the gas pressure of the air delivery tube 102, so as to avoid excessive expansion of the extension tube 104 due to excessive pressure.

[0078] Drug infusion tube 109: Made of medical-grade fluororesin, it is coaxially fitted into the inner ring of the air chamber 107. One end is connected to the inner catheter 110, and the other end extends to the outside and connects to the "drug injector interface". The inner wall of the drug infusion tube 109 is coated with an "anti-adsorption coating" to reduce drug adsorption on the tube wall and ensure accurate drug dosage.

[0079] Spring coil 111: Made of medical-grade nickel-titanium alloy, it is linearly distributed along the fixing groove on the outer surface of the inner catheter 110. The two ends of the spring coil 111 are fixed to the inner catheter 110 by laser welding. The spring coil 111 has shape memory characteristics (recovery temperature 37℃), which can maintain the axial stability of the inner catheter 110 in the body and prevent the catheter from bending in tortuous blood vessels. At the same time, the spring coil 111 can enhance the support between the inner catheter 110 and the outer catheter 101 and reduce lumen deformation when the diameter changes.

[0080] The three-way valve 106 control knob: clockwise rotation is "air intake" (controls the extension tube 104 to expand, increasing the outer diameter of the conduit); counterclockwise rotation is "air exhaust" (controls the extension tube 104 to contract, decreasing the outer diameter of the conduit). The knob is marked with scales (0-5 levels, corresponding to an outer diameter change of 0-0.8mm) for precise control of the diameter change range.

[0081] How to use:

[0082] Preoperative preparation: Assemble the outer catheter 101 and inner catheter 110 of the microcatheter, connect the external air source through the air hole 108 of the air chamber 107, and connect the drug injection tube 109 to the drug injection syringe; turn on the power of the operating handle, and check whether the pressure sensor and flow sensor are working properly and whether the LED indicator light is green.

[0083] Catheter insertion and positioning: Under DSA image guidance, the microcatheter is slowly inserted into the cerebral blood vessel along the guidewire. The position of the catheter is observed by contrast markers until the distal end approaches the target area (such as aneurysm or vascular malformation).

[0084] Segmented diameter adjustment operation: Rotate the corresponding three-way valve 106 control knob according to the required change in blood vessel diameter.

[0085] When passing through a narrow blood vessel segment (e.g., 1 mm in diameter), rotate the knob on the distal segment (fourth segment) to release air, the extension tube 104 contracts, and the outer diameter of the distal end of the catheter decreases from 1.8 mm to less than 1 mm, allowing it to pass through the narrow segment smoothly.

[0086] Once the target area is reached, rotate the corresponding knob to allow air in, the extension tube 104 expands, and the outer diameter of the catheter increases to match the diameter of the blood vessel, achieving stable fixation and preventing catheter displacement.

[0087] When a local diameter change is required at a branch vessel, only rotate the knob corresponding to the branch segment (e.g., only adjust the third segment) to achieve local outer diameter adjustment without affecting other areas;

[0088] Drug delivery: Press the drug delivery button to deliver the embolic agent or drug to the target area through the delivery tube 109. If a stent needs to be delivered, push the stent to the target position through the inner catheter 110. The spring coil 111 ensures the stability of the inner catheter 110 and prevents the catheter from deviating during pushing.

[0089] Postoperative recovery: After the treatment is completed, press the emergency exhaust button to expel all the gas in the gas inlet tube 102, restore the catheter to its initial outer diameter, and slowly withdraw the microcatheter to complete the operation.

[0090] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The scope of patent application of the present invention should not be limited by these embodiments. That is, any equivalent changes or modifications made in accordance with the spirit disclosed in the present invention still fall within the patent scope of the present invention.

Claims

1. A variable diameter interventional microcatheter, characterized in that, The utility model relates to a variable-diameter outer conduit (101) and a variable-diameter assembly arranged inside the outer conduit (101). The variable-diameter assembly comprises a plurality of variable-diameter units arranged along the axial direction of the outer conduit (101), each of which is configured to expand or contract according to the pressure of the medium inside, so as to adjust the radial size of the outer conduit (101) in segments. The variable-diameter assembly comprises:

2. The variable diameter interventional microcatheter of claim 1, wherein, a plurality of gas conveying pipes (102) arranged inside the outer conduit (101), which extend along the axial direction, the extending ends of the gas conveying pipes (102) correspond to and communicate with the variable-diameter units, and the head ends of the gas conveying pipes (102) are configured to fill or discharge gas; a control valve arranged at the head end of each gas conveying pipe (102), which is configured to control the pressure of the medium conveyed by the gas conveying pipe (102). Each variable-diameter unit comprises:

3. The variable diameter interventional microcatheter of claim 2, wherein, a connecting pipe (103) arranged outside the gas conveying pipe (102) along the circumferential direction of the outer conduit (101), which communicates with the gas conveying pipe (102); an extension pipe (104) arranged on the side of the connecting pipe (103) facing the inner wall of the gas conveying pipe (102), which communicates with the connecting pipe (103) and can expand or contract according to the pressure of the medium inside. In each variable-diameter unit, the number of connecting pipes (103) is multiple, which are arranged in sequence along the axial direction of the outer conduit (101); the number of extension pipes (104) is multiple, which are arranged in sequence along the circumferential direction of the connecting pipe (103).

4. The variable diameter interventional microcatheter of claim 3, wherein, The gas conveying pipes (102) are arranged in sequence along the circumferential direction of the outer conduit (101), the connecting pipes (103) are arranged in a ring shape, and the connecting pipes (103) penetrate the outer surface of the gas conveying pipes (102); in the variable-diameter units adjacent in the axial direction of the outer conduit (101), the connecting positions of the connecting pipes (103) and the gas conveying pipes (102) are arranged in sequence along the circumferential direction of the connecting pipes (103).

5. The variable diameter interventional microcatheter of claim 3, wherein, The size of the extension pipe (104) gradually increases away from the connecting pipe (103); the outer wall of the extension pipe (104) does not exceed the outer wall of the outer conduit (101).

6. The variable diameter interventional microcatheter of claim 3, wherein, The variable-diameter assembly further comprises:

7. The variable diameter interventional microcatheter of claim 3, wherein, a gas guide pipe (105) having one end communicating with the head end of the gas conveying pipe (102), the control valve being installed on the gas guide pipe (105), and the other end of the gas guide pipe (105) being communicated with a gas chamber (107), the gas chamber (107) being installed with a gas hole (108) and a pressure sensor on the side away from the outer conduit (101). ​ 8. The variable diameter interventional microcatheter of claim 7, wherein, The air chamber (107) is annular, an inner ring of which is sleeved with a medicine delivery tube (109), another end of the medicine delivery tube (109) is communicated with an inner guide tube (110), the inner guide tube (110) is arranged in the inner side of the outer guide tube (101), and a delivery channel is prearranged in the inner guide tube (110); The gas delivery tube (102) and the variable diameter unit are located between the outer guide tube (101) and the inner guide tube (110).

9. The variable diameter interventional microcatheter of claim 8, wherein, A support structure is arranged between the inner guide tube (110) and the outer guide tube (101), the support structure is a plurality of spring rings (111), the spring rings (111) are sequentially arranged along the axial direction of the inner guide tube (110), the spring rings (111) are embedded between the inner guide tube (110) and the outer guide tube (101), and the spring rings (111) are spring rings (111) with shape memory characteristics.

10. The variable diameter interventional microcatheter of claim 3, wherein, The gas delivery tube (102) is divided into a first gas delivery tube, a second gas delivery tube, a third gas delivery tube and a fourth gas delivery tube which are sequentially arranged in the circumferential direction of the outer guide tube (101); The length of the gas delivery tube (102) is equal to the length of the outer guide tube (101) and the end portions are flush arranged, the first gas delivery tube, the second gas delivery tube and the third gas delivery tube are provided with closed portions, the closed portion on the first gas delivery tube is located at 1 / 4 of the total length, the closed portion on the second gas delivery tube is located at 1 / 2 of the total length, the closed portion on the third gas delivery tube is located at 3 / 4 of the total length, and the fourth gas delivery tube is communicated with the connecting pipe (103) at the end.

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