A catheter specifically designed for aspiration of distal cerebral vascular thrombi

Abstract

The present invention relates to a catheter specially used for aspirating thrombus at the distal end of cerebral blood vessels, which is composed of a catheter seat, a stress release tube and a tube body. The main part of the tube body is composed of three layers, namely, an inner layer, a braided layer and an outer layer. The outer layer material is designed in sections, which is designed according to the physiological and anatomical structure of cerebral blood vessels and provides corresponding flexibility according to different sections of blood vessels. The catheter is mainly made of one or more of nylon 12, PEBAX and TPU polyester materials which cooperate with each other. The outer layer material of the catheter of the present invention is segmented according to the physiological and anatomical structure of cerebral blood vessels and provides corresponding flexibility and pushing performance according to different sections of blood vessels, so that the catheter can effectively adapt to the blood vessel structure and facilitate the catheter to reach the lesion position.

Description

Technical Field

[0001] The invention relates to a device for brain tube surgery, in particular to a catheter for treating cerebrovascular diseases. Background Art

[0002] Cerebral infarction, also known as ischemic cerebrovascular disease, is a disease caused by insufficient blood supply due to thrombosis, embolism or other reasons in the cerebral blood vessels. The number of deaths from acute cerebrovascular disease in my country accounts for 36% of the total number of deaths, and it is one of the common diseases that seriously endanger the health of middle-aged and elderly people. Intravenous re-tissue plasminogen activator is a method approved by the US FDA for acute ischemic stroke, but due to the limited treatment time after the onset of symptoms, only a small number of patients are treated. In addition, the effect of intravenous treatment of large vessel occlusion is limited.

[0003] Recently, the emergence of intra-arterial mechanical thrombectomy devices has delayed the time for the occluded artery to reopen to 8 hours after the onset of stroke, further improving the rate of vascular recanalization. Stent thrombectomy uses a minimally invasive interventional treatment method to place the thrombectomy stent at the site of the thrombus through a catheter. After a few minutes, it combines with the thrombus, directly grasps the thrombus, and pulls the thrombus out of the cerebral blood vessels, allowing the occluded blood vessels to reopen. However, stent thrombectomy also has its disadvantages. Stent thrombectomy requires micro-guidewires and distal micro-catheter operations, and the stent needs to pass through the thrombus, which requires high requirements for beginners and the treatment cost is also relatively expensive.

[0004] With the continuous innovation and development of neurointerventional technology, doctors have proposed the ADAPT technology, which is to treat acute stroke by removing thrombi with aspiration catheters. The ADAPT technology can improve the recanalization rate and shorten the recanalization time. In addition, the use of the ADAPT technology is safe and effective, with fewer device-related complications than stent thrombectomy and 0 symptomatic bleeding.

[0005] The existing thrombus aspiration systems on the market are represented by Navien catheters and Penumbra catheters. Current clinical data tell us that Navien and Penumbra also have many problems and cannot meet clinical needs. The middle layer of the Navien tube body is a spring structure, which does not have good pushing performance, and the distal flexibility of the Navien catheter is poor, and it cannot reach the lesion through the tortuous vascular path. The middle layer of the Penumbra catheter is also a spring structure, which lacks good force transmission performance, and the Penumbra lumen is small, and the suction effect is poor. In summary, the thrombus aspiration catheters currently on the market cannot meet the clinical needs of ADAPT technology. The current catheters cannot effectively reach the expected lesion location, the operation is cumbersome, and they do not have good suction performance against negative pressure, resulting in exceeding the golden treatment time of thrombectomy surgery and endangering life. Therefore, medical staff and patients are eager for a cerebral vascular aspiration catheter with simpler surgery, which can reach the lesion location and has better suction performance. Summary of the invention

[0006] The purpose of the present invention is to provide a cerebral vascular thrombus aspiration catheter with good flexibility, which can reach the tortuous lesion position and has a larger inner cavity, so as to effectively facilitate the doctor's operation and save the time of thrombus aspiration surgery.

[0007] In order to solve the above technical problems, the present invention is implemented as follows: 1. A catheter specially used for aspiration of distal thrombus in cerebral blood vessels, which is composed of a catheter seat, a stress release tube and a tube body, and the main part of the tube body is composed of three layers, an inner layer, a braided layer and an outer layer;

[0008] The outer layer material is designed in sections, based on the physiological and anatomical structure of the cerebral blood vessels, and provides corresponding flexibility according to different sections of the blood vessels; it is mainly made of one or more of nylon 12, PEBAX, and TPU polyester materials;

[0009] The middle layer adopts a double-layer structure combining a braid layer (Braid) and a spiral layer (Coil). The braid layer is made of heat-treated 304 stainless steel flat wire material, consisting of 12 to 20 flat wires, with a braiding density of preferably 60PPI at the proximal end and 80 to 100PPI at the distal end; the braid is in a mesh shape, and the spiral layer is wound around the braid layer;

[0010] The inner layer is made of PTFE material, and the wall thickness of the inner tube is 0.001; the top of the tube body corresponding to the M segment and the M2 segment is only composed of the inner layer and the outer layer; a spring is added at the distal end; the diameter of the spring wire is preferably 0.0015 inches, the pitch is preferably 0.0035 inches, and the material is preferably 304 stainless steel; a C-shaped developing ring is installed at the distal end; the top of the tube body is extended to the intracranial M1 or M2 segment; the thrombus suction operation is directly performed after entering the M1 or M2 segment.

[0011] The segmentation of the outer material of the catheter of the present invention is designed according to the physiological and anatomical structure of the cerebral blood vessels, and provides corresponding flexibility and pushing performance according to different segments of the blood vessels, so that the catheter can effectively adapt to the blood vessel structure and facilitate the catheter to reach the lesion site.

[0012] The middle layer of this solution is a braided layer. The middle layer adopts a double-layer structure combining a braided layer (Braid) and a spiral layer (Coil). The braided structure can provide the catheter with good pushing performance and torsion performance. The spring layer can provide good negative pressure resistance during thrombus aspiration, which can reach the distal M2 segment (middle cerebral artery encircling segment) and has good aspiration performance. The outer layer material of the distal end of the catheter uses a polymer material with very low hardness, which provides good flexibility for the catheter and facilitates the catheter to reach the lesion location.

[0013] The inner layer is preferably made of PTFE material, and the wall thickness of the inner tube is 0.001", which meets the requirements of high temperature resistance, corrosion resistance, low friction coefficient, non-adhesion and non-toxicity.

[0014] The distal end of the catheter of this solution is a C-shaped developing ring, which can provide good radial elasticity during the pushing process, making it easier to pass through the tortuous cerebral vascular system. At the same time, during the thrombus aspiration process, the C-shaped developing ring design provides good radial tension, making it easier for the thrombus to be aspirated into the catheter.

[0015] The above scheme as a whole needs to meet the following requirements:

[0016] (1) The length of the product can be designed to meet the required vascular location according to different lesion types, and the farthest can reach the distal M2 segment (middle cerebral artery circumferential segment). In order to facilitate the identification of the product position, it must be visible under X-ray, especially the distal end must be clearly visible under X-ray. The specific segmented design is shown in the following embodiment. The radiopaque material is preferably barium sulfate, bismuth subcarbonate, etc. added to the outer layer material.

[0017] At the same time, the distal diameter of the product should be suitable for the blood vessel to be reached and should not exceed the blood vessel diameter to be reached. The product is designed with two outer diameters, one of which can reach the M2 segment (the middle cerebral artery circumferential segment) and the other can reach the M1 segment (the horizontal segment of the middle cerebral artery).

[0018] (2) The product tube body is designed in sections according to the anatomical structure of the cerebral blood vessels. The characteristics of each section of the blood vessels are taken into consideration in the design to balance the appropriate length and hardness of each section of the product. The anatomical diagram of the cerebral blood vessels is as follows, including the extracranial segment of the internal carotid artery (C1), petrous segment (C2), foramen rupture segment (C3), cavernous sinus segment (C4), clinoid segment (C5), ophthalmic artery segment (C6), posterior communicating segment (C7), horizontal segment of the middle artery (M1), and circumferential segment of the middle artery (M2).

[0019] In order to comprehensively consider the pushing ability and overall performance of the catheter, the catheter is divided into a three-layer structure: inner layer, braided layer, and outer layer.

[0020] In order to enhance the support force at the proximal end, the hardness of the proximal material needs to be enhanced, including the material hardness of the braided layer, PPI (braiding density), braiding method, and the selection of the material of the outer layer.

[0021] The outer layer material is made of nylon 12, PEBAX, TPU and other polyester materials.

[0022] The middle layer adopts a double-layer structure combining a braid layer (Braid) and a spiral (Coil). The braid layer uses heat-treated 304 stainless steel flat wire material. The weaving density is preferably 60PPI (mesh per inch) at the proximal end to achieve better support, and 80PPI (mesh per inch) at the distal end to achieve better flexibility.

[0023] The inner layer is preferably made of PTFE material, and the wall thickness of the inner tube is 0.001", which meets the requirements of high temperature resistance, corrosion resistance, low friction coefficient, non-adhesion and non-toxicity.

[0024] (3) The catheter needs to be flexible, especially the flexibility of the bending material at the front end. At the same time, it must have good bending ability, torsion transmission ability, anti-bending ability, and good lubricity when passing through each section of the blood vessel. When the product is delivered through the catheter sheath, it should be smooth and without resistance. When the product passes through the corresponding microcatheter in the lumen, the microcatheter is easy to deliver without bending. At the same time, it is necessary to ensure that the lumen is large enough to meet the requirements of the outer diameter to meet the requirements of interventional operations.

[0025] The above-mentioned design requires that the inner diameter is large enough, while the outer diameter is limited, that is, the wall thickness is controlled. At present, the inner diameter achieved by the present invention can meet the minimum breakthrough of 1.804mm, and the maximum outer diameter can be controlled at 2.133mm.

[0026] (4) After the product is in place, when the syringe is connected to the negative pressure suction, the lumen will not be deflated, and effective and continuous suction must be ensured during the negative pressure. In order to meet the above design requirements, the present invention breaks through the distal E segment (see attached Figure 3 ) The technical difficulty of adding Coil (spring) is to meet the requirements of both flexibility and resistance to negative pressure suction, where the spring wire diameter is preferably 0.0015", the pitch is preferably 0.0035", and the material is preferably 304 stainless steel.

[0027] The above technical solution is further refined, the inner diameter of the catheter is controlled within 1.804mm, and the maximum outer diameter can be controlled at 2.133mm. The catheter is made in sections, from proximal to distal, they are sections A, B, C, D, E, and F; the process of each section is the same or different. The distal tip of the catheter should be smooth, and the distal tip is designed as the first section. The outer layer is polyester elastomer and mixed nylon. The outer layer of sections A and B is made of nylon elastomer mixed with 20% Baso4; the outer layer of section C is made of polyurethane TPU mixed with 20% Baso4, and the outer layer of sections D, E, and F is made of a composite material of polyether and polyamide with 20% (BIO)2CO 3。 The woven mesh of the middle weave of D and E is 80PPI, and the size is 0.003"*0.001". The inner layer is dip coated.

[0028] The structure disclosed in this article is suitable for establishing a distal access and thrombus aspiration guide catheter in the treatment of cerebrovascular diseases. The structure has high burst pressure resistance, fracture strength, tensile strength, flexibility, torsion transmission ability, bending resistance, and good self-lubrication. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Diagram of cerebral vascular anatomy.

[0030] Figure 2 The overall structure of the product.

[0031] Figure 3 Schematic diagram of the pipe body segmentation.

[0032] Figure 4 Schematic diagram of the shaping needle.

[0033] Figure 5 Schematic diagram of the guide sheath.

[0034] In the figure, 1-catheter seat, 2-stress relief tube, 3-tube body

[0035] The following detailed description and the accompanying drawings to which it refers are intended to describe some, but not necessarily all, examples of the present invention. The described embodiments are considered to be merely illustrative and not restrictive in any way. The content of the detailed description and the accompanying drawings do not limit the scope of the present invention in any way.

[0036] A, B, C, D, E, and F represent segments of the tube from the proximal end to the distal end. In this article, the terms proximal and distal refer to the direction along the longitudinal axis of the catheter. The proximal end refers to the catheter end closer to the operator, and the distal end refers to the catheter end closer to the patient.

[0037] 1. According to the present invention, there is provided a method for accessing the cerebral vascular system by an interventional method, wherein the access Figure 1 The M1 segment and even the M2 segment shown are very difficult, and currently no similar catheter product can enter the M2 segment to directly aspirate the thrombus.

[0038] The method comprises the following steps: the clinician shapes the tip of the catheter according to the location and condition of the patient's cerebrovascular lesions: Figure 4 The shaping needle shown is bent to the desired shaping angle and carefully placed into the distal end of the catheter. The shaping needle and the catheter are steamed together for 30 seconds, and the distal end of the catheter is immediately placed into saline to fix the shape, and then the shaping needle is removed from the catheter.

[0039] Prior to use, flush the lumen of the guide catheter with heparinized saline solution. Continuous flushing with heparinized saline is recommended between the guide catheter and any intraluminal device coaxially passed through the catheter. The hydrophilic coating on the catheter should be hydrated with heparinized saline solution prior to use to keep it moist. Using the selected percutaneous puncture technique, introduce the guide catheter through the catheter puncture sheath and into the vasculature over the guidewire. Continuously flush with heparinized saline through the rotating hemostatic valve side arm fixed on the Luer lock of the guide catheter sheath. Under fluoroscopic monitoring, advance over the guidewire until the desired position is reached. Remove the guidewire before introducing other intravascular devices and perfusing contrast media. During thrombectomy, negative pressure is applied to the proximal end of the catheter or the connected aspiration port to aspirate thrombus emboli into the catheter. Attachment Figure 1 The overall structure of the guide catheter is given.

[0040] 2. According to the present invention, an effect visible under X-ray is provided, and a barium sulfate component is preferably added to the proximal outer layer material, and a bismuth subcarbonate component is preferably added to the distal outer layer material.

[0041] Attached Figure 2 A schematic diagram of the product in sections and a cross-sectional view of the catheter body are given.

[0042] 2.1 Segment design description:

[0043] In order to reduce the damage to blood vessels during use, the distal tip of the catheter should be smooth and designed as the first section

[0044] The diameter of the M1 segment is 2.5 to 4.0 mm, and the length is 12 to 30 mm; there is a bifurcation angle of 90° to 120° from C7 to M1;

[0045] Segment analysis: The diameter of the blood vessels is small here, and the catheter part of the M1 segment has the most tortuous paths; therefore, it must have good flexibility, small radial force of the catheter, and be easy to bend, but it must have a certain pushing performance, so the distal second segment of the catheter is designed here

[0046] The C3 segment (rupture foramen segment) runs from the internal opening of the carotid canal through the rupture foramen to the petroglossal ligament, with a bend and a diameter of about 4 to 8 mm.

[0047] The length of the horizontal part is 15-25 mm, the length of the vertical part is 6-15 mm, the angle is about 100°, and the angle between C3 and C4 is about 120°

[0048] C4 segment (cavernous sinus segment): From the horizontal line above the petroglossal ligament to the anterior clinoid process, the diameter increases, presenting an S-shape or C-shape in front and back, with varying degrees of tortuosity. Starting from C3, it is divided into the posterior ascending segment, horizontal segment, and anterior ascending segment, with a diameter of 4 to 5.5 mm.

[0049] C5 segment (clinoid segment): the part between the distal dural ring and the proximal dural ring, with a diameter of 4 to 5 mm;

[0050] C6 segment (ophthalmic artery segment): diameter is about 3.5-5 mm, length is about 5-11 mm, and it bends posteriorly and superiorly;

[0051] C7 segment (posterior communicating segment): diameter 3.5-4.5 mm;

[0052] Segment analysis: The diameter of the blood vessels in the C3-C7 segment is greater than 4mm. There is a siphon bend in the C3 segment. The angle between C3 and C4 is 120°. C4 is S-shaped and C-shaped in front and back, with different degrees of tortuosity. Therefore, the C3-C7 path is relatively tortuous. The diameter of the C3-C7 segment gradually decreases. Therefore, this segment must have sufficient flexibility, that is, the radial force is small. The C3-C7 segment catheter needs slightly better axial pushing performance, so C3-C7 is the third distal segment of the catheter.

[0053] C2 segment (petrous segment): inside the carotid canal, it is divided into a vertical segment entering the skull and a horizontal segment. The vertical segment is about 2 to 10 mm, the horizontal segment is about 12 to 20 mm, and the angle is 90 to 100°.

[0054] C1 segment (extracranial segment): internal diameter 4-7 mm, from bifurcation to petrous bone;

[0055] Segment analysis: The C1 segment path is relatively straight and easier to pass through, but this catheter requires better push delivery, so it is the fifth distal segment.

[0056] Femoral artery to left common carotid artery: maximum diameter of the common artery end is 6-8 mm, maximum inner diameter of the internal carotid artery origin is 4-6 mm

[0057] Segment analysis: The blood vessels from the femoral artery to the common carotid artery are larger in size, less curvature, and require good support, so this is the sixth segment.

[0058] 2.2 Layered design:

[0059] According to the present invention, the catheter product is designed as a three-layer structure of an inner layer, a braided layer, and an outer layer.

[0060] The design requirements of the inner layer pipe are: high temperature resistance, corrosion resistance, low friction coefficient, non-adhesion, and non-toxic.

[0061] PTFE is resistant to high temperatures, has a low coefficient of friction, is non-adhesive, and has no adverse reactions when implanted in the body as artificial blood vessels and organs, so we prefer PTFE as the inner layer material in our design.

[0062] Middle layer design:

[0063] The middle layer of the medical guide catheter is the core of the entire product. It has a mesh structure made of braided wire and a coiled Coil (spring) structure. Its function is to make the catheter resistant to breakage and twisting, while also giving it a certain degree of compliance and elasticity. Based on the above characteristics, 304 stainless steel meets the design requirements.

[0064] Analysis of influencing factors shows that currently round wire and flat wire are commonly used. Under the same cross-sectional area, round wire has smaller radial force, and flat wire can reduce wall thickness and increase inner cavity.

[0065] Clinical feedback shows that the distal end of Sofia (E segment is a braid) has poor anti-suction ability and is easily sucked flat. The E segment has low requirements for axial force. The use of a Coil (spring) structure can enhance the E segment's ability to resist negative pressure.

[0066] Outer material design: The outer material of the guiding catheter determines its shape, hardness and friction with the vascular endothelium. Therefore, the material selection should be easy to process, light, soft and tough, with good resilience and good resistance to flexural fatigue, and less loss of mechanical properties under repeated deformation. Among the many polymer materials, polyester elastomers and mixed nylon can meet the above requirements.

[0067] The following are two attached tables showing specific embodiments of the 5F catheter tube body and the 6F catheter tube body of the present invention:

[0068] Appendix 1: 5F catheter body example

[0069]

[0070] Appendix 2: 6F catheter body example

[0071]

Claims

1. A catheter specially used for aspiration of distal thrombus in cerebral blood vessels, which is composed of a catheter seat, a stress release tube and a tube body, and is characterized in that: The main part of the tube is composed of three layers: inner layer, braided layer, and outer layer; The outer layer material adopts segmented design, which is designed according to the physiological and anatomical structure of cerebral blood vessels, and provides corresponding flexibility according to different segments of blood vessels; The middle layer is a braided layer, which adopts a double-layer structure combining a braided layer and a spiral layer. The braided layer is made of heat-treated 304 stainless steel flat wire material, woven from 12 to 20 flat wires, with a braiding density of 60PPI at the proximal end and 80 to 100PPI at the distal end; the braiding is a mesh, and the spiral layer is wound around the braided layer; the inner layer is made of PTFE material, and the wall thickness of the inner tube is 0.001 inches; The outer layer is made in sections, from the proximal end to the distal end, they are sections A, B, C, D, E, and F; each section has a different process; The outer layers of sections A and B are made of nylon elastomer mixed with 20% BaSO4; the outer layer of section C is made of polyurethane TPU mixed with 20% BaSO4, and the outer layers of sections D, E, and F are made of a composite material of polyether and polyamide mixed with 20% (BiO)2CO3; The tube body at the top end of the tube body corresponding to the M1 segment and the M2 segment is only composed of an inner layer and an outer layer; a spring coil is added to the inner layer of the distal E segment; wherein the spring wire diameter is 0.0015 inches, the pitch is 0.0035 inches, and the material is 304 stainless steel; a C-shaped developing ring is installed at the distal end; the top end of the tube body is extended to the intracranial M1 or M2 segment, and the thrombus suction operation is directly performed by entering the M1 segment or the M2 segment; M1 is the horizontal segment of the middle cerebral artery of the cerebral blood vessel, and the M2 segment is the circumferential segment of the middle cerebral artery; The inner diameter of the catheter is controlled within 1.804mm, and the maximum outer diameter is controlled within 2.133mm.

2. The catheter for aspiration of distal cerebral vascular thrombus according to claim 1, characterized in that: The distal tip of the catheter is smooth, and the distal tip is designed as the first section.

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