Suction catheter

Abstract

A system and method for performing aspiration thrombectomy is disclosed. The aspiration catheter assembly can include a support catheter and an aspiration catheter extending through the support catheter. The catheter assembly can include a distal valve device that can control the level of vacuum at the distal end of the catheter system. Irrigation fluid can be passed between the support catheter and the aspiration catheter to flush the catheter assembly.

Description

Technical Field

[0001] [Incorporation by reference to any priority applications] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 200,995, entitled "Devices and Methods for Increasing Suction," filed Apr. 7, 2021, and U.S. Provisional Patent Application No. 63 / 267,031, entitled "Suction Catheter," filed Jan. 21, 2022, the entireties of which are hereby incorporated by reference herein.

[0002] Any and all applications identified in the application data sheet submitted herewith as claiming foreign or domestic priority are subject to 37 C.F.R. § 1.57 and are hereby incorporated by reference herein.

[0003] [Field] The present disclosure relates to suction thrombectomy.

Background Art

[0004] [Description of Related Art] Thromboembolism is a disease caused by blood clot formation. In the venous system, thromboembolism presents two different peripheral manifestations: deep vein thrombosis (DVT) and pulmonary embolism (PE). Venous thromboembolism is a major cause of death and disability worldwide and is the third most common vascular diagnosis in the United States after myocardial infarction and stroke. Researchers estimate that there are approximately 1 million patients with venous thromboembolism in the United States each year, with 600,000 hospitalizations. As a result, in the United States, approximately 60,000 to 180,000 people die within the first 30 days each year, and the direct medical costs associated with venous thromboembolism are estimated to exceed $10 billion annually.

[0005] Blood clots and their effects are, by their nature, heterogeneous and unpredictable. Thrombi can have various forms.

[0006] Arterial blood clots are subjected to high flow velocity and high shear forces. Clinically significant blood clots are typically found in vessels with a diameter of 1.5 mm to 7 mm. Arterial blood clots are soft but can harden over time. As blood clots grow larger and older, their responsiveness to anticoagulants decreases.

[0007] On the other hand, blood clots in peripheral veins are subjected to lower flow velocities and lower shear forces. Clinically significant venous blood clots can typically be found in vessels with a diameter of 3 mm to 25 mm. Pulmonary embolism clots are harder, more viscous, and larger in volume than arterial clots. Anticoagulants are dangerous because they are contraindicated in many pulmonary embolism patients. Typically, the response to systemic anticoagulants is suboptimal due to the size of the clots. Deep vein thrombosis shares similar characteristics with pulmonary embolism and can adhere to the vessel wall. Deep vein thrombosis can release blood clots that can lead to pulmonary embolism.

[0008] Due to the characteristics of the vascular system and blood clot morphology, the size and hardness of the underlying blood clot can increase with age by the time thromboembolism is diagnosed. Consequently, methods designed to remove new, soft blood clots may be insufficient and ineffective in removing larger, older clots associated with venous thromboembolism. Current products are cumbersome and often suffer from poor delivery due to rigid catheters and complex mechanical components.

[0009] Of the population, 40-50% develop sub-extensive pulmonary embolism, and 5-10% develop extensive pulmonary embolism. The size of blood clots may be underestimated because the flow of contrast agent is difficult in the presence of large blood clots. Anticoagulants can reduce the risk of future blood clots, but their use for clot removal typically requires a 12-24 hour procedure, and they may not break down or remove existing blood clots, significantly increasing the patient's bleeding risk. [Overview of the Initiative]

[0010] Aspiration thrombectomy is a standard endovascular procedure for removing occlusive thrombi, such as those that cause ischemic stroke. During aspiration thrombectomy, a suction catheter (typically 90-165 cm in length, with a diameter adapted to the size of the vessel being treated) is used, with a vacuum source attached to its proximal end and the thrombus aspirated at its distal end. The vacuum source creates a low-pressure area, which contributes to the suction force. This can be likened to using a household vacuum cleaner hose to suck up dirt and particles. A syringe may also be used to create the vacuum.

[0011] Current solutions for thromboembolism do not offer an effective and reproducible approach to mechanical thrombectomy. Most mechanical thrombectomy systems are based on flawed assumptions, such as the requirement to provide larger diameter catheters. However, larger catheters lead to decreased deliverability and stiffness in the catheter system, causing blockages and excessive blood drainage.

[0012] Furthermore, current mechanical thrombectomy systems are designed to remove soft, young blood clots and encounter difficulties when faced with older, harder, and larger clots. Conventional aspiration systems have difficulties with extensive and subextensive pulmonary embolism due to poor delivery, clot shape, clot volume, and thrombus composition. Consequently, procedures using conventional systems are significantly longer due to the complex procedural methods, multiple catheter removals for clot lavage, and the operations required for mobilizing and aspirating the clot.

[0013] Current solutions for aspiration thrombectomy are based on an accompanying force that is much smaller than the suction force predicted by a simple calculation such as suction force = (blood pressure - vacuum pressure) × area. The suction force may be insufficient to adequately aspirate large or dense thrombi that may become lodged at the distal end of the aspiration catheter. To remove a thrombus lodged at the distal end of the catheter, the physician must pull the thrombus, along with the catheter, out of the patient's body along the entire insertion route of the catheter. This process can be likened to pulling a fish (thrombus) out of the water with a hook at the end of a fishing line (catheter). Once the fragments of the blood clot are removed from the tip, the catheter can be reinserted to continue the process and retrieve any remaining portion.

[0014] When dealing with blood clots in the brain, time is of the essence, and the treatment window for successful recovery is limited. Current aspiration methods are time-consuming and inefficient, and particles can separate from the blood clot during the withdrawal process, which can lead to future embolisms or blockages of smaller blood vessels, potentially causing further damage in the case of ischemic stroke. Furthermore, this method requires repeated removal and reinsertion of the catheter, resulting in longer overall procedure times and an increased risk of vascular damage and complications. These risks are particularly high when using aspiration thrombectomy to treat ischemic stroke, but they also exist when treating blood clots in the legs or venous system.

[0015] As mentioned above, it is a widely accepted view and design convention that suction force is a function of the cross-sectional area of ​​the suction catheter and the pressure applied to the proximal end of the catheter. Both factors are limited and have reached their limits in current designs. The theoretical maximum vacuum pressure is limited to a theoretical minus 29.92 inHg in the pump (it is well known that the overall pressure difference is higher because blood pressure is higher than atmospheric pressure), and the internal cross-section of the suction catheter is determined by the size of the blood vessel being treated. Veins and some peripheral arteries are relatively large in diameter (4-14 mm or more), while distal vessels of the lower extremities are approximately 4 mm or less, and cerebral arteries are typically in the range of 2.5 mm or less. Current suction pumps can only reach 80%-95% of the maximum vacuum pressure, but catheter technology has been improved so that thin-walled suction catheters can have wall thicknesses as thin as 0.1 mm to maximize their cross-sectional area, and sometimes slightly improved with the use of chamfered tips. These limitations have led to a deadlock in this field, with procedures still not optimal, and improvements being limited by the physical laws governing the steady-state pressure difference. Furthermore, when the vacuum pressure is placed within the anatomical structure of the human body, it decreases rapidly with the length and curvature of the suction catheter. Several measurements have shown that, a few seconds after the pump is turned on, near the blood clot where it is most needed, the vacuum pressure at the tip of the catheter can drop to as low as 10 inHg, sometimes even 3-5 inHg, making suction less effective for the rapid and complete removal of the blood clot. Attempts have also been made to improve suction efficiency by slowly "fatiguing" the blood clot using vibrating vacuum pumps, but these methods have not become standard treatment due to their minimal improvement and difficulty with larger, more complex clots. In fact, these methods can further increase the total suction time, as the vacuum pump transitions from 29.92 inHg to lower pressures (to generate pulses), and the average is lower than the maximum. Also, because it is pulsatile, it can contribute to distal embolism. The forces generated by these methods are limited by the maximum vacuum force, which is the only energy supplied to the system that generates force.

[0016] If the flow is not completely blocked, the pressure at the distal end of the catheter (static or pulsating) will never approach the pressure applied at the proximal end of the suction (near the vacuum source) due to losses in the small diameter suction tube and the damping effect of the fluid and particles already present in the tube. In fact, as mentioned above, the distal pressure is only slightly lower (by more than the blood pressure difference) than the pressure of the fluid surrounding the suction tip, resulting in a weak suction force and a large damping effect, which further contributes to inefficiency. This can be likened to the pressure profile of a long pipe with a pump at one end. Due to friction and damping forces, the pressure continues to decrease along the length of the pipe and with each bend or change of direction in the pipe. In aspiration thrombectomy, this pressure loss is caused by the small suction tube lumen radius and the anatomical structure of the curved human blood vessels, which require the catheter to be fitted into narrow vessels.

[0017] In standard aspiration thrombectomy, the force that aspirates the thrombus is the resistance between the blood flowing into the catheter tip and the thrombus, also known as the accompanying force. The accompanying force, like the resistance, is a function of the fluid velocity. The distal pressure approaches the pressure applied by the vacuum source only when the distal tip is completely blocked, blood flow stops, and distal vacuum pressure accumulates. However, to reach this level of blockage, the thrombus must be adhering to the distal tip, obstructing any further aspiration and effectively leading to malfunction.

[0018] Current thromboembolic removal solutions on the market fail to provide an effective and reproducible approach to mechanical thrombectomy. No currently available devices offer a complete, effective, and predictable solution for venous, peripheral, or neurovascular structures. The aspiration catheter system described herein is designed to address clinical demands and overcome many of the limitations of currently available products. The system addresses the effectiveness of peripheral blood clot removal regardless of age, size (length and diameter), solidity, or location, while reducing the risk of bleeding.

[0019] One or more features described herein contribute to these improved results. For example, the suction catheter system described herein maintains maximum suction force at the distal tip (e.g., at least about 90% of the vacuum pressure at the vacuum source, or at least about 95% of the vacuum pressure at the vacuum source, or at least about 98% of the vacuum pressure at the vacuum source, or at least about 99% of the vacuum pressure at the vacuum source). The valve assembly described herein allows pressure to accumulate at the distal end of the catheter assembly, thereby improving blood clot collection when the valve opens. Resistance can be reduced by taking advantage of the physical weaknesses of the blood clot structure. Since blood clots are five times less resistant to shear force than to the tension used in conventional suction, shear force can be used to break up the blood clot, reducing its length and friction.

[0020] In some embodiments, the suction catheter system can provide simultaneous perfusion to minimize blockage and occlusion during the procedure. The hydraulic column can increase the pressure within the catheter assembly beyond the theoretical maximum vacuum pressure supplied by a single vacuum source. This self-cleaning mechanism removes blood clots without the need to remove the device during the procedure. Using these features, the suction catheter system can remove larger blood clots in less time without removing or manipulating the catheter system.

[0021] In some embodiments, the suction catheter system may include a dual-catheter design with an outer support catheter and an inner suction catheter. One or both catheters may have braided and / or coiled reinforcements with non-invasive tips that facilitate guidance into vascular structures.

[0022] A suction catheter can be operably connected to any vacuum source. Unlike current thrombectomy approaches that use pulsatile vacuum, the vacuum source can apply a constant or continuous vacuum throughout the procedure. There is no valve to regulate the vacuum pressure at the vacuum source or the proximal end of the catheter assembly. Instead, the catheter assembly reduces pressure loss along the length of the suction catheter assembly, amplifying the clot removal force. For example, a support catheter may include a valve in the distal portion of the support catheter. When the valve is closed, pressure can be accumulated at the distal end of the catheter assembly. When the valve is open, the suction catheter can aspirate at least a portion of the blood clot. Using shear force, the suction catheter assembly can break the blood clot into smaller fragments, reducing blockage. These features make this catheter assembly suitable for all types of blood clots. Reducing blockages reduces the number of replacements, thereby making the procedure quicker and less labor-intensive. Furthermore, periodically closing the valve further increases the shear force while minimizing blood loss from the suction catheter.

[0023] Valve control can be performed manually or automatically. Automated systems can incorporate safety features to stop suction when discontinuous suction is detected. Furthermore, the system can collect input regarding blood clot characteristics or catheter performance to modify valve control and optimize suction.

[0024] Optionally, the support catheter can be operably connected to an irrigation source, for example, to provide saline irrigation during aspiration. The irrigation fluid can flow distally through the space between the support catheter and the aspiration catheter, into the distal end of the aspiration catheter, and then flow back proximal from the aspiration catheter towards the vacuum source. Perfusion facilitates aspiration and can minimize blockage. This reduces the need for separate catheter irrigation during the procedure. Irrigation can be performed continuously during the thrombectomy procedure, independently of the application of vacuum. There are no valves to regulate perfusion at the irrigation source or the proximal end of the catheter system. The irrigation source can be pressurized (e.g., by pressurizing or increasing the pressure of the saline bag using a pressure pump), further increasing the overall pressure difference. Without such a system, the theoretical maximum pressure difference would be the pressure plus (minus) blood pressure provided by the vacuum source. Thus, this would be approximately 1 bar, with some difference due to blood pressure. In current systems, it is possible to significantly increase this pressure difference, and it may be possible to double the pressure difference by providing a pressurized irrigation source. This pressure is added to the vacuum pressure during the backflow irrigation cycle.

[0025] Certain aspects of this disclosure relate to a suction catheter assembly for removing blood clots. The suction catheter assembly may include a support catheter configured to connect to an irrigation source for fluid flow, and a suction catheter configured to connect to a vacuum source for fluid flow. The suction catheter may be disposed within the support catheter and may be movable relative to the support catheter. The suction catheter may include a suction lumen for receiving at least a portion of the blood clot. The suction catheter assembly may include a valve for controlling the level of vacuum at the distal end of the suction catheter assembly and / or for preventing perfusion from the distal end of the suction catheter assembly. For example, the support catheter may include a single valve for controlling the vacuum at the distal end of the suction catheter assembly and / or for preventing perfusion from the support catheter. In some embodiments, the valve opens as the suction catheter advances through the valve, and closes as the suction catheter is drawn proximal to the valve.

[0026] The support catheter may include a long tubular body and a valve at or near the distal end of the support catheter, for example, within 5 cm from the distal end, within 1 cm from the distal end, within 0.5 cm from the distal end, or at the distal end of the support catheter. The valve may be a one-way valve, such as a slit valve, a valve with a leaflet, or a valve with a projection such as a duckbill valve. The valve may include a rim surrounding the valve opening sufficient to break up blood clots. The valve can control the level of vacuum pressure at the distal end of the suction catheter assembly by accumulating pressure when the valve is closed. The valve can also prevent the irrigation fluid from flowing out of the support catheter when the valve is open and / or closed.

[0027] In some embodiments, the support catheter can include a valve housing fixed to the distal end of a long tubular body. The distal end of the valve housing can be at the distal end of the support catheter. The distal end of the valve housing can be tapered. The valve housing can be located radially outward of the long tubular body and can be fixed to the outer surface of the long tubular body. However, in other configurations, the valve housing may be inserted into the long tubular body. The valve can be disposed within the valve housing. The distal end of the support catheter, which can be the valve housing, can form a cutting shoulder for tearing blood clots.

[0028] The aspiration catheter can include an aspiration lumen for receiving at least a portion of a blood clot. In some embodiments, the working length of the aspiration catheter can be at least as long as the working length of the support catheter. In other embodiments, the working length of the aspiration catheter can be less than the working length of the support catheter. Movement of the aspiration catheter relative to the support catheter can be restricted by stoppers in the support catheter and / or the aspiration catheter.

[0029] Any of the catheter assemblies described herein can include a manifold in the proximal portion of the aspiration catheter assembly. The manifold can be fixed to the proximal end of the support catheter. The aspiration catheter can extend proximally to the manifold for connection to a vacuum source. The manifold can include an inlet for irrigation fluid. The manifold can include a seal member that forms a seal with the aspiration catheter and can prevent fluid in the space between the support catheter and the aspiration catheter from flowing out of the proximal end of the manifold.

[0030] The movement of any catheter assembly described herein may be manual or automatic. When automatic, the aspiration catheter assembly may include a drive unit attached to or integrated with the aspiration catheter. The drive unit may include a motor operably connected to the aspiration catheter. The catheter assembly may include a controller, either within or separately from the drive unit. The controller may cause the motor to advance and retract the aspiration catheter relative to the valve of the support catheter according to a pre-selected pattern or in response to blood clot parameters or the operation of the aspiration catheter assembly.

[0031] The catheter assemblies described herein can form part of a suction catheter system including a vacuum source. The vacuum source communicates with the suction catheter and can apply a constant vacuum through the suction lumen. The applied vacuum pressure may be constant and continuous.

[0032] The catheter assemblies described herein may form part of a suction catheter assembly that includes an irrigation source. The irrigation source can deliver the irrigation fluid distally through the space between the support catheter and the suction catheter. When the suction catheter extends through the valve, the seal between the suction catheter and the valve can prevent the irrigation fluid from flowing out from the distal end of the support catheter. When the suction catheter is retracted through the valve, the valve can prevent the irrigation fluid from flowing out from the distal end of the support catheter.

[0033] Certain aspects of this disclosure relate to a method for removing a blood clot using a suction catheter assembly having any of the features described herein. The method may include a step of applying a vacuum to the proximal portion of the suction catheter assembly. The applied vacuum may be constant and continuous over the removal of the blood clot. The method may include a step of opening and closing the flow to the distal portion of the suction catheter assembly. This step may be performed, for example, by opening and closing a valve by advancing and retracting the suction catheter toward the distal end of a support catheter. The method may include a step of repeatedly opening and closing the flow to the distal portion of the suction catheter assembly to remove the blood clot, for example, at least twice per second, at least five times per second, or at least ten times per second. The flow may be opened and closed over a variety of time periods. The flow may be opened for a longer time than the flow is closed. For example, the flow can be interrupted for at least approximately 0.05 seconds (or at least approximately 0.1 seconds, or at least approximately 0.25 seconds, or at least approximately 0.5 seconds) and opened for approximately 1 second or less (or 0.5 seconds or less, or 0.25 seconds or less, or 0.5 seconds or less). The steps of opening and closing the flow can be performed manually or automatically.

[0034] When the flow is released in the distal portion of the suction catheter assembly, the suction catheter assembly can aspirate at least a portion of the blood clot through the suction lumen of the suction catheter assembly. When the flow is blocked in the distal portion of the suction catheter assembly, the vacuum pressure in the distal portion of the suction catheter assembly increases. For example, if the diameter of the suction lumen is 1 mm to 3 mm, the absolute pressure in the distal portion of the suction catheter assembly can be at least about 15 inHg (or at least about 20 inHg, at least about 25 inHg, or at least about 30 inHg). The vacuum pressure in the distal portion of the suction catheter system can be at least about 50% (or at least 80%, at least 85%, at least 90%, or at least 95%) of the vacuum pressure applied to the proximal portion of the suction catheter.

[0035] A particular method may include the steps of applying a vacuum to a suction catheter and delivering irrigation fluid through the space between the suction catheter and the support catheter, extending through the support catheter. The method may include advancing the suction catheter distal to the support catheter to aspirate at least a portion of the blood clot through the suction lumen of the suction catheter and retracting the suction catheter to block the fluid flow at the distal end of the support catheter. This step can be repeated to remove the blood clot. By applying a vacuum, irrigation fluid can flow from the space between the suction catheter and the support catheter into the distal end of the suction catheter. This can propel the blood clot through the suction lumen. In some methods, the flow of irrigation fluid may be constant when the flow is opened and closed. In other methods, the flow of irrigation fluid may be intermittently stopped when the flow is open at the distal end of the suction catheter assembly.

[0036] Any feature, structure, or step disclosed herein may be replaced with, combined with, or omitted from any other feature, structure, or step disclosed herein. Furthermore, for the purpose of providing an overview of this disclosure, specific aspects, advantages, and features of the invention are described herein. It should be understood that not all or any of such advantages are necessarily achieved according to any specific embodiment of the invention disclosed herein. Individual aspects of this disclosure are neither essential nor indispensable.

[0037] Various embodiments are described in the accompanying drawings, which are intended to be illustrative, and should not be construed in any way as limiting the scope of the embodiments. Furthermore, various features of the various embodiments disclosed may be combined to form further embodiments, which are part of this disclosure. [Brief explanation of the drawing]

[0038] [Figure 1A-1D]Figures 1A to 1D show the cycle of the suction catheter exiting and returning to the distal valve. Figure 1A shows the suction catheter moving towards the closed distal valve. Figure 1B shows the distal valve opening and the suction catheter grasping the thrombus. Figure 1C shows the suction catheter being pulled back into the support catheter and cutting the thrombus fragment. Figure 1D shows the cut thrombus fragment being aspirated when the suction catheter is behind the closed valve. [Figure 2] Figure 2 shows a simplified mechanism of a clogged suction catheter. [Figure 3] Figure 3 shows a simplified mechanism of a suction catheter that prevents blockage during aspiration by breaking down the thrombus into smaller fragments. [Figure 4] Figure 4 shows a schematic diagram of the entire suction catheter extending through the support catheter. [Figure 5] Figure 5 shows a schematic diagram of the entire other suction catheter, which is actuated by a push wire that extends through a portion of the support catheter and extends the remaining length to the proximal end of the support catheter. [Figure 6A-6B] Figures 6A and 6B show cross-sectional views of the distal cap device used to secure the valve to the support catheter. [Figure 7] Figure 7 shows a cross-sectional view of another system in which valve fixation material is heat-bonded to the support catheter on both sides of the valve, securing the valve to the support catheter. [Figure 8A-8B] Figures 8A and 8B show cross-sectional views of the suction catheter and support catheter. Figure 8A is an exploded view, and Figure 8B is an assembled view. [Figure 9A] Figure 9A shows a cross-sectional view of the system, which allows fluid to enter the gap between the support catheter and the suction catheter, so that thrombi are continuously aspirated through the suction tube lumen even when the distal valve is closed. [Figure 9B] Figure 9B shows the same embodiment in the active phase, where there is no flow between the support catheter and the aspiration catheter. [Figure 10]Figure 10 shows a cross-sectional view of another system in which a stopper joint prevents the insertion of a suction catheter beyond a safe distance. [Figure 11] Figure 11 shows the suction catheter assembly. [Figure 12] Figure 12 shows a suction catheter system equipped with a vacuum source and an irrigation source. [Figures 13A-13E] Figures 13A to 13E show a method for aspirating blood clots using an aspiration catheter assembly. [Figure 14] Figure 14 shows the distal segment of the suction catheter assembly. [Figures 15A-15B] Figures 15A and 15B show typical records of vacuum pressure filling and release at the distal tip of the catheter assembly when the flow is stopped and restarted using the suction catheter assembly. [Modes for carrying out the invention]

[0039] This disclosure provides a device for treating and removing intravascular thrombi by aspiration thrombectomy to address the challenges outlined above and to significantly enhance the ability to remove blood clots. Specific aspects of this disclosure relate to a device for aspiration thrombectomy equipped with a valve that significantly improves the transmission of vacuum pressure from the proximal end to the distal end of the suction lumen, and thus reduces or eliminates the attenuation effect, which is the pressure drop gradient between the vacuum pump and the tip of the suction catheter (typically 90 cm to 165 cm or longer depending on the anatomical structure of the target and specific appendages). The valve can be located at the distal end of the catheter system. In this case, the suction catheter becomes vacuumed without being subjected to longitudinal and temporal attenuation effects that hinder the current product. This system allows for the application of immediate, short-range, transient force effects applied directly to the blood clot by utilizing an active distal valve without significantly impairing the catheter lumen (which contributes to the steady-state pressure difference). This can be done without pulsating the flow in the pump or altering the flow in the proximal portion of the suction catheter system. For example, a pump can operate at a constant flow rate.

[0040] A suction catheter assembly may include two working components: (1) a valved support catheter and (2) an internal vacuum suction catheter that fits inside the valved support catheter and is capable of rapid relative movement manually or automatically. The valved support catheter may include a valve device positioned close to or at the distal end of the support catheter, with a recess extending from the distal tip, allowing the distal end zone of the support catheter to function as a thrombus-cutting shoulder. For example, the valve device may be positioned within 15 cm, 10 cm, 5 cm, 1 cm, 0.5 cm, or less from the distal end of the support catheter.

[0041] As shown in Figures 1A to 1D, the catheter assembly includes a suction catheter 2 housed within a support catheter 1, which moves distally toward the valve 4 (Figure 1A) so that the suction catheter 2 grasps the blood clot 5 when it opens the distal valve 4 (Figure 1B). As shown in Figure 1C, the suction catheter 2 is then pulled back behind the valve 4, stretching the blood clot 5 between the suction catheter 2 and the outer wall (or part of the support catheter 1) of the support catheter 1 (referred to here as the thrombus cutting shoulder 6). The shoulder 6 may be the end of the suction catheter 2 and / or the support catheter 1. The blood clot 5 is cut along the thrombus cutting line 7. Figure 1D shows the suction of the cut blood clot 5 fragments when the suction catheter 2 is behind the closed valve 4.

[0042] As shown in Figures 1A to 1D, the distal region of the support catheter 1 may include a valve 4. The distal region can be within 15 cm of the distal tip of the support catheter, within 10 cm of the distal tip, within 5 cm of the distal tip, within 1 cm of the distal tip, or the distal tip of the support catheter. The suction catheter 2 operates through the valve 4, for example, being pushed out, protruding from the support catheter 1, and being pushed back into the support catheter 1. By pushing the suction catheter 2, the valve 4 can be opened outward. This allows a seal to be formed between the valve 4 and the suction catheter 2. In other configurations, the suction catheter is initially positioned outside the valve, and the lumen can be opened by pulling the valve inward. Optionally, the tip of the suction catheter may be chamfered to apply greater force to the blood clot as it protrudes through the valve. The suction catheter and / or support catheter may include side holes so that the suction catheter can direct suction to its sides. This helps prevent thrombi from adhering around or on the distal tip. The suction catheter can be the same length as the support catheter or longer, but it can also be constructed using a short (1cm to 5cm or longer) distal segment actuated by a push wire.

[0043] This system operates as a "grasp and pull" combination, where the continuous vacuum in the suction lumen 3 and the suction catheter 2 "grasp" the blood clot when it protrudes outside the valve 4 of the support catheter 1. The vacuum force is not strong enough to deform or cut the blood clot and may be less than the blood clot's maximum resistance, causing the resisting blood clot to "get stuck" and block the vacuum in the suction lumen 3 (see Figure 1B). At that point, the suction catheter is rapidly pulled back proximal to the valve (see Figure 1C), and the mechanical tensile force is added to the vacuum force, so the maximum force applied to the thrombus is greater than the maximum force that can be generated by the vacuum pump (total force = vacuum suction force + rapid pull force). This combination generates a combined force greater than the blood clot's maximum resistance, and therefore splits the blood clot at the cutting shoulder of the distal tip of the support catheter, which is designed to be rigid enough to cut the blood clot. Because blood clots are viscoelastic, they respond not only to total force but also to the speed of loading, so rapid retraction has another significance. Rapid retraction allows the viscoelastic blood clot material to be cut with less force than applying a gentle or quasi-static force. The cut shoulder contributes to the three-dimensional stress field applied to the blood clot, creating tensile and shear strains that do not exist in the same way in other suction systems (this is why suction attempts generally fail to remove blood clots in a "single pass" when dealing with resistant blood clots). The mechanical tensile and shear forces from the cut shoulder enhance the maximum force that the suction vacuum pump can generate by adding a mechanical tensile component that cannot be produced by a vacuum pump (continuous vacuum or pulsating vacuum). As the suction catheter enters and passes through the valve, the valve seals, and the blood clot fragments, torn apart by the stress field, receive maximum vacuum, are aspirated to the proximal end of the device, and expelled from the body. This will be explained in more detail with reference to Figures 2 and 3 below.

[0044] As the suction catheter 2 is drawn into the valve 4, the suction is converted into a vacuum that "fills" the suction catheter 2, bringing the vacuum to the tip of the suction catheter and avoiding the damping effect of the tube and the curved anatomical structure. The suction catheter 2 is then pushed out, and the process continues. This allows for a significant improvement in outcomes, including the ability to break resistant blood clots and reduce procedure time.

[0045] Conventional suction catheters often become clogged because the suction force is insufficient to continue pushing further thrombi into the suction lumen or to cleave thrombus fragments within the catheter from the rest of the thrombus (see Figure 2). However, in the system described herein, the force used to pull the suction catheter back behind the membrane as it protrudes from and returns to the seal valve is added to the suction force applied to the thrombus. Together, these forces are sufficient to cleave the aspirated fragments from the rest of the thrombus, preventing clogging and clearing the suction lumen to take in further thrombi (see Figure 3).

[0046] Thrombi containing more fibrin and being cross-linked can clog conventional aspiration catheters, regardless of the vacuum source parameters (continuous or pulsating), obstructing fluid flow or aspiration until the entire system must be removed from the body, significantly delaying the procedure and increasing the risk of distal embolism. Such clogs have been called extrusion clogs in the art because the thrombus stretches and conforms to the shape of the aspiration lumen as it is aspirationed towards the proximal end of the aspiration catheter. These extruded thrombus segments clog because even the maximum vacuum pressure difference does not provide enough energy to cut and separate the thrombus. Figure 2 shows a simplified mechanism of a clogged aspiration catheter 2. In pure aspiration thrombectomy, the suction force is less than the force required to cut the thrombus. This causes the thrombus 5 to become lodged in the tip of the aspiration catheter 2, preventing sufficient aspiration and delaying treatment.

[0047] In the systems described herein, these blockages are prevented by increasing the maximum force well beyond the maximum force that can be produced by the pressure gradient of any vacuum suction pump (all limited by the theoretical maximum pressure difference). This prevents suction blockages by cutting and separating the blockage and reducing the volume of the thrombus fragments being aspirated. Figure 3 shows a simplified mechanism of an example system of this disclosure that prevents blockages during aspiration by dividing the thrombus 5 into smaller fragments. The retraction force used to pull in the suction catheter 2 is added to the suction force via friction applied to the thrombus 5 in the contact area with the suction catheter 2. The sum of these two forces is sufficient to exceed the yield stress of the thrombus, separating the smaller fragments of the thrombus from the larger mass. This smaller fragment can then be successfully aspirated while the suction catheter is advanced to grasp another thrombus fragment and start this cycle again.

[0048] Because this thrombus-cutting function occurs only within the support catheter, the possibility of severed thrombus fragments being released into the vascular structure as smaller emboli is minimized. This is further aided by a "vacuum-filling valve" that allows for a complete vacuum within the aspiration catheter without attenuation effects and provides a large force kick (vacuum force surge) as the aspiration catheter protrudes through the valved support catheter. The vacuum at the distal end of the aspiration catheter, when filled, can be at least about 90%, at least about 95%, at least about 98%, or at least about 99% of the vacuum supplied by the vacuum source. Combined with its ability to cut blood clots, this reduces procedure time. While the system can still cut resistant blood clots even without the valve, the dual-catheter system may have longer procedure times than the single-catheter system due to its smaller cross-sectional area. The volumetric flow rate of fluid passing through a smaller cross-sectional area is inherently smaller, and the vacuum-filling valve adequately compensates for the smaller cross-sectional area.

[0049] With a blood clot 3.5 cm long and 7.5 mm in diameter, a suction lumen 1 mm in diameter, and a vacuum pressure of 24 in Hg applied to the proximal side of the suction catheter, the clot removal time is 2.5 minutes without a valve and 1.5 minutes with a valve. In the dual-catheter assembly described herein, the clot-cutting shoulder can remove resistant blood clots by utilizing an added mechanical force component. The distal edges of support catheter 1 and / or suction catheter 2 can be made sufficiently rigid to cut the blood clot. This valve reduces the procedure time measured in the laboratory model by at least 40%, which can have life-changing results for patients in some procedures. A further time reduction of at least 10% can be achieved by using the self-cleaning cycle shown in Figures 9A and 9B.

[0050] The valves described herein may be made from one or more layers of polymers such as silicone, but may also be made from other materials including thin nitinol or flexible metal, ethylene vinyl acetate, polyurethane, PTFE, nylon or Pebax, and in some cases, biological tissue. The valve design provides sufficient rigidity to stop the flow of fluid when the suction catheter is retracted, and sufficient fit to allow the tip of the suction catheter to be exposed to blood. The valve leaflets may be cut into slit-like, triangular, semicircular, or other shapes. The leaflets may overlap each other to ensure that a good seal is formed when the valve is closed. The valve thickness may be 0.05 to 2.0 mm, for example 0.1 to 1.0 mm. The leaflets may also be reinforced with more robust wires or fibers made from stainless steel, nitinol, or harder polymers. The valve may have 2 to 10 leaflets, for example 3 to 8. The valve may be located within the distal region of the support catheter, or it may be recessed within the distal tip of the support catheter up to 10 mm, and in some cases up to 100 mm, depending on the target vessel (head, neck, leg, or vein). The valve may be recessed only 1.0 mm to 10.0 mm within the distal tip of the support catheter. The concave valve may have a portion of the support catheter that extends distally to the distal surface of the valve. When a thrombus extends beyond the distal end of the support catheter, it will be aspirated into the aspiration catheter, and when the aspiration catheter is drawn in, the thrombus will be pulled toward the distal end of the support catheter, creating a three-dimensional stress field including shear and tensile stresses that contribute to the cutting of the aspirated thrombus fragments. Thus, this portion of the support catheter forms a thrombus-cutting shoulder that dramatically improves the aspiration effect. The concave valve also makes the device safer by preventing the aspiration catheter from penetrating the wall of the vascular structure when exposed through the valve.

[0051] Silicone offers high resistance to fatigue and can provide a good seal for many cycles of insertion and withdrawal of the suction catheter. The valve can be heat-bonded or mechanically fixed within the shaft of the support catheter.

[0052] In some embodiments, the silicone valve can be fixed within the suction tip by inserting the distal end of the support catheter and the silicone valve into a valve fixing cap (also referred to herein as the valve housing). The valve can be held in place radially and / or distally by the cap material. The valve can be held in place proximal by the support catheter. In this way, the valve can have material on both sides, allowing for its mechanical fixation. Figures 6A and 6B show schematic cross-sectional views of this configuration. The valve may be exposed to the suction lumen up to a certain radius, and beyond that radius, proximal and distal, it can be supported by the material, by a valve support lip of the material. In neurovascular applications, the radial thickness of this valve support lip can be 0.1 mm to 1.0 mm, for example, 0.1 mm to 0.3 mm, depending on the overall diameter of the valve. For peripheral or venous applications, the dimensions can be larger. The outer diameter of the fixing cap can be the same as the outer diameter of the support catheter. In this case, the support catheter can be swaged so that the valve fixing cap can be attached without increasing the overall outer diameter of the distal tip.

[0053] Figures 6A and 6B show cross-sectional views of a configuration in which the valve housing 16 is used to fix the valve 4 to the support catheter 1. Figure 6A shows only the valve housing 16 and the valve 4. Figure 6B shows the suction catheter 2 and the support catheter 1 inserted into the valve housing 16. The support catheter 1 can be fixed to the valve housing 16 by the use of an adhesive applied through a hole 17 in the valve housing 16. The valve 4 can be held in place by materials on both sides that can form a cap support protrusion 20. The valve housing 16 may include a distal wall portion 19 that can form a gap 18 between the distal end of the valve housing 16 (or suction catheter system) and the valve 4. This gap 18 holds the thrombus 5 at a distance from the valve 4 during suction, and the wall portion of the valve housing 16 forms a thrombus cutting shoulder portion 6.

[0054] In some embodiments, the valve can be fixed within the suction tip of the support catheter by embedding the valve between two pieces of valve fixing material that can be heat-bonded within the distal tip of the support catheter. Figure 7 shows a schematic cross-sectional view of this configuration. Figure 7 shows a cross-sectional view of an alternative form of the valve housing, in which the valve fixing material 21 is heat-bonded within the support catheter 1 on both sides of the valve 4, fixing the valve 4 within the support catheter. The valve may be exposed to the suction lumen up to a predetermined radius and supported beyond that radius in the proximal and distal directions by a valve fixing material that substantially embodies a valve support lip of material. The radial thickness of this valve support lip can be 0.1 mm to 1.0 mm, for example, 0.1 mm to 0.3 mm, and varies with the overall diameter of the valve. The valve support material may include polymers such as silicone or nylon or other known polymers, as well as materials containing metals such as nitinol and certain elastic alloys, as well as composite materials or fabrics.

[0055] Both the suction catheter and the support catheter may be lined with Teflon® or other materials to enhance lubrication. The suction catheter or a portion thereof may be made from a more rigid material, such as braided metal, to facilitate operation through the distal valve. The suction catheter may be the same length as the support catheter, or shorter (see Figure 5), and in many cases, longer than the support catheter to have a connection to a vacuum pump (see Figure 4). The suction catheter can be operated back and forth through the valve manually or automatically.

[0056] Figure 4 shows a schematic diagram of the overall configuration in which the catheter assembly extends through the head 13 to the neurovascular structure 14. The suction catheter 2 extends along the entire length of the support catheter 1. The vacuum source 8 can be attached to the catheter hub 12 (also referred to herein as the manifold) via the suction source tube 9. In some embodiments, the hub 12 may include or be operably connected to a camshaft with a battery 10 and a motor 11. The motor 11 moves the suction catheter 2 to automatically move out of and back from the valve 4.

[0057] In some embodiments, as shown in Figure 5, the suction catheter is shorter than the support catheter and is attached to a metal wire or mandrel that may extend to a proximal operating mechanism. Figure 5 shows a schematic diagram of another configuration in which the suction catheter 2 extends through part of the length of the support catheter 1. A vacuum source 8 may be attached to the catheter hub 12 via a suction source tube 9. A camshaft with a battery 10 and motor 11 is either outside the hub 12 or part of the hub 12. This motor 11 moves the suction catheter 2 to automatically move out of and back through the valve 4 via a push wire 15.

[0058] In these configurations, the number of system operations is not limited, but a vacuum can be applied to the support catheter 1, allowing the suction catheter 2 to be exposed distally to the valve 4 2 to 10 times per second. This translates to an exposure time of approximately 0.05 seconds and / or 0.25 seconds or more (depending on the system calibration and operating parameters), and the valve 4 is filled posteriorly in at least 0.05 seconds and / or 0.25 seconds or more, although with asymmetric operating parameters, the filling time may increase to 0.5 seconds or more, providing sufficient time to open the suction lumen, allowing pressure to build up and enabling a sudden increase in vacuum force in addition to mechanical force, thus maximizing the possibility of a temporary power surge. The suction catheter 2 may be exposed distally to the valve 4 for a shorter time than when the suction catheter 2 is posterior to the valve 4. The suction time may be approximately 1 second or less, or approximately 0.5 seconds or less, approximately 0.25 seconds or less, or approximately 0.1 seconds or less, or approximately 0.5 seconds or less. For example, the suction time may be approximately 0.5 seconds to 0.25 seconds, or 0.25 seconds to 0.5 seconds, or 0.5 seconds to 1.0 seconds. The filling time may be approximately 1 second or less, approximately 0.5 seconds or less, approximately 0.25 seconds or less, approximately 0.1 seconds or less, or approximately 0.5 seconds or less. For example, the filling time may be approximately 0.5 seconds to 0.25 seconds, or 0.25 seconds to 0.5 seconds, or 0.5 seconds to 1.0 seconds. In some methods, the suction time may be the same as the filling time. In other methods, the suction time may be less than the filling time.

[0059] The suction catheter may also contact the support catheter in a screw-like manner, allowing it to rotate and retract in one or the other direction, providing additional shear force.

[0060] The lumen of a suction catheter may have a circular opening with a diameter that conforms to the anatomical structure of the target. In most applications, the inner diameter of the suction catheter ranges from 0.5 mm to 6 mm for arteries and 10 mm or more for veins, and in specific embodiments, it may have various diameters specific to that application. For example, the diameter may be at least about 1 mm and / or about 12 mm or less, for example, at least about 3 mm and / or about 12 mm or less, for example, between about 1 mm and about 3 mm, between about 2 mm and about 4 mm, or between about 3 mm and about 6 mm. For example, when calibrated for use in ischemic stroke, the diameter of the inner lumen opening of the suction catheter may range from 0.030 to 0.070 inches, and in extreme cases, it may range from 0.020 to 0.090 inches.

[0061] The gap between the suction catheter and the support catheter can be sealed by design or by a vacuum sealant material such as a sheet of polyurethane or other polymer that can be installed between the proximal ends of the support catheter and the proximal end of the suction catheter, preventing air from being drawn in from the outside of the support catheter (if the boundary between the tubes is outside the body lumen) and maintaining a good vacuum at the distal end. Alternatively, both the proximal ends of the suction catheter and the support catheter can be held within a larger vacuum seal container.

[0062] Alternatively, as shown in Figure 9A, the fluid may enter this space between the inner suction catheter 2 and the outer support catheter 1 along the flow path 23. Figure 9A shows a cross-sectional view of a configuration in which the fluid flow 23 enters the gap between the support catheter 1 and the suction catheter 2, so that the thrombus 5 is continuously aspirated through the suction lumen 3 even when the distal valve 4 is closed. The fluid that enters this space can enable a small, continuous fluid flow, as shown in Figure 9B. Figure 9B shows the same embodiment in which the suction catheter 2 extends through the valve 4 and there is no flow from the support catheter 1 to the suction catheter 2. In some methods, perfusion can be stopped as the suction catheter 2 advances through the valve 4. However, in other methods, perfusion can be continued regardless of whether the valve 4 is open or closed.

[0063] If a small amount of fluid (blood if from within the body, or other fluid from a designated reservoir or feedback system) can thus enter, fragments of the thrombus 5 that have been severed and aspirated into the suction catheter 2 will be continuously aspirated at a greater rate through the suction lumen 3 when the suction valve 4 is closed, providing self-cleaning and further enhancing the effectiveness of the system by reducing the total suction time. This mechanism ensures that fragments of the severed thrombus 5 do not obstruct the tip of the suction catheter 2 when the tip of the suction catheter 2 moves through the valve 4 in the active state to sever another fragment of the thrombus 5. Fluid can be supplied to the space between the suction catheter 2 and the support catheter 1 by a separate fluid supply lumen within the body of the support catheter 1, or by a separate lumen led into the body parallel to the support catheter 1. This fluid may be blood, saline solution, or other solution of water and some solute supplied from an external saline source. Figures 9A and 9B show the operating states: (1) as shown in Figure 9B, the suction catheter 2 exits the valve 4 and actively aspirates the thrombus 5, and (2) as shown in Figure 9A, the suction catheter 2 is inside the support catheter 1, the valve 4 is sealed, and self-washing is enabled.

[0064] To prevent distal pressure on vascular trauma or thrombus, the suction catheter 2 cannot rapidly protrude beyond a safe distance from the valve 4. Such a distance is assessed for each target anatomical structure (peripheral, coronary, neurovascular, or others) depending on the size and complexity of the surrounding anatomical structures. To prevent this, a stopper can be used proximal to the valve. As an example of a stopper, the proximal end of the suction catheter 2 may have the same outer diameter as the support catheter 1 up to a certain point (around reference numeral 22). Distal to that point, the outer diameter of the suction catheter 2 can be made smaller than the inner diameter of the support catheter 1. This stopper joint 22 allows the suction catheter 2 to be inserted into the support catheter 1 to a predetermined length and limits insertion beyond that length. This embodiment is shown in Figure 10. Figure 10 shows a cross-sectional view of a configuration in which the stopper joint 22 prevents insertion of the suction catheter 2 beyond a safe distance. Other mechanisms to prevent the suction catheter 2 from protruding too far include mechanical, electrical, and pneumatic solutions. For example, Figures 8A and 8B show a separate stopper 22 positioned around the suction catheter 2. In another example, the drive unit can be configured to limit the travel distance of the suction catheter 2.

[0065] Figure 11 shows a catheter assembly 100 of a suction catheter system. The catheter assembly 100 may include any of the features of the catheter system described above, including an outer support catheter and an inner suction catheter.

[0066] Figure 12 shows a suction catheter system having a catheter assembly 100 operably connected to a vacuum source 150 and an irrigation source 160. The suction catheter system may include a container 170 for collecting blood clots and fluids aspirated by the catheter assembly 100. In the method described herein, the vacuum source and / or irrigation source can supply a continuous and constant flow or pressure.

[0067] Figures 13A to 13E are schematic diagrams of the catheter assembly 100 at various stages of a thrombectomy procedure. As shown, the catheter assembly 100 may include an outer support catheter 102 and an inner suction catheter 104 extending through the support catheter 102.

[0068] The suction catheter 104 can define the suction lumen 106. The suction catheter 104 can be operably connected to a vacuum source (see Figure 12). The vacuum source can cause the suction catheter 104 to aspirate the blood clot C through the suction lumen 106.

[0069] The suction catheter 104 may include a polymer material having a reinforcing braid or coil. The outer diameter of the suction catheter 104 can be at least about 1.0 mm and / or about 12.0 mm or less, for example 2.0 mm to 10.0 mm, for example 5.0 mm or less, 4.0 mm or less, or 3.0 mm or less. The wall thickness of the suction catheter 104 can be about 0.5 mm or less, about 0.4 mm or less, about 0.3 mm or less, about 0.2 mm or less, or about 0.1 mm or less.

[0070] As shown in Figure 13A, the suction lumen 106 can have a constant diameter. The distal segment of the suction catheter 104 may contain a first material, and the proximal segment of the suction catheter may contain a second material having different properties, for example, a different rigidity than the first material.

[0071] In other embodiments, the suction lumen 106 may have a variable diameter such that the distal portion of the lumen 106 has a smaller diameter than the proximal portion of the lumen 106. As shown in Figure 14, the suction catheter 104 may include a distal segment 104a joined to a proximal segment 104b. The distal segment 104a and the proximal segment 104b may be made of the same material or different materials. For example, the proximal segment 104b may be harder than the distal segment 104a. The distal segment 104a may have a first inner diameter, and the proximal segment 104b may have a second inner diameter that is larger than the first inner diameter. The distal segment 104a may extend into the proximal segment 104b such that the outer surface of the distal segment 104a is joined to the inner surface of the proximal segment 104b. The outer diameter of the proximal segment 104b may be smaller than the inner diameter of the valve housing 110. The transition between the distal segment 104a and the proximal segment 104b can form a stop joint that prevents the suction catheter 104 from moving a predetermined distance beyond the distal end of the support catheter 102. For example, the suction catheter may only extend 5 cm or less (or 3 cm or less, or 2 cm or less, 1 cm or less, 0.5 cm or less, or 0.1 cm or less) beyond the distal end of the support catheter 102. However, if a blood clot remains in a small distal vessel, in "exploration" mode, it is possible to complete the procedure by manually or gently extending the suction tube a longer distance from the support tube to capture this remaining blood clot and quickly pull it back into the support tube.

[0072] The support catheter 102 may include a long tubular body. The long tubular body may include a polymer material having a reinforcing braid or coil. One or more radiopaque markers may be placed along the long tubular body.

[0073] The inner diameter of the support catheter 102 can be made larger than the outer diameter of the suction catheter 104 to leave a space 108 for fluid to flow between the two catheters. The outer diameter of the support catheter 102 can be at least about 1.0 mm and / or about 12.0 mm or less, for example 2.0 mm to 10.0 mm, or 3.0 mm to 5.0 mm. The inner diameter of the support catheter 102 can be at least 0.1 mm larger than the outer diameter of the suction catheter 104, for example at least about 0.1 mm larger than the outer diameter of the suction catheter 104, and / or about 1.0 mm or less larger than the outer diameter of the suction catheter 104, for example about 0.25 mm to about 0.75 mm larger than the outer diameter of the suction catheter 104. The wall thickness of the support catheter 102 can be about 0.5 mm or less, about 0.4 mm or less, about 0.3 mm or less, about 0.2 mm or less, or about 0.1 mm or less.

[0074] The support catheter 102 may include a valve 112 at or near the distal end 116 of the elongated tubular body. For example, the valve 112 may be within 15 cm (or 10 cm, or 5 cm, 1 cm, 0.5 cm, or 0.1 cm) of the distal end 116 of the elongated tubular body. The valve 112 can be disposed inside or outside the lumen of the support catheter 102. The valve 112 can be fixed to the elongated tubular body using any of the features described above with respect to the valve 4.

[0075] As illustrated, the valve 112 can be fixed to a long tubular body by a valve housing 110. The valve housing 110 can protect the blood vessel wall from the valve 112. The valve 112 can be disposed within the valve housing 110 such that the valve housing 110 extends distally and / or proximal to the valve 112. The valve 112 can be fixed within the valve housing 110 mechanically or chemically.

[0076] The valve housing 110 can be fixed to the distal end 116 of the elongated tubular body, for example, by welding or adhesive. The valve housing 110 can also be fixed to the outer surface of the elongated tubular body. The valve housing 110 can be made from plastic or metal.

[0077] The inner diameter of the valve housing 110 may be larger than the inner diameter of the elongated tubular body. However, in other configurations, the valve housing 110 may extend into the elongated tubular body. The diameter of the opening at the distal tip 114 may be less than or equal to the inner diameter of the distal end 116 of the elongated tubular body. The distal tip 114 of the valve housing 110 may form the distal tip of the support catheter 102. The distal tip 114 of the valve housing 110 may be tapered. A tapered distal tip 114 may function as a cutting shoulder for breaking or dividing blood clots. This helps to divide harder blood clots.

[0078] When assembled, the distal end 116 of the elongated tubular body may abut the proximal side of the valve 112 to maintain the position of the valve 112 within the valve housing 110. The distal end 116 of the elongated tubular body may be spaced away from the proximal-facing surface of the valve 112 to allow the irrigation flow to enter the suction catheter 104.

[0079] The valve housing 110 is optional. The valve 112 may be incorporated directly into or on a long tubular body. For example, a metal ring can be placed inside the valve 112 and welded to a reinforcing structure within the long tubular body.

[0080] Valve 112 can be a one-way valve. As shown in the figure, valve 112 is a duckbill valve, but may include any of the valve features described above. Valve 112 can be any valve with an opening edge that is rigid enough to divide blood clots. Valve 112 may be any valve through which the suction catheter 104 can advance and retract. For example, valve 112 may be a slit valve, or a valve with overlapping leaflets having an edge suitable for valve division. The inner diameter of valve 112 may be less than the inner diameter of the support catheter 102, but greater than the outer diameter of the suction catheter 104.

[0081] The catheter assembly 100 may include a manifold 118 at the proximal end of the support catheter 102. The manifold 118 may include an inlet 120 for connecting to an irrigation source (see Figure 12). The manifold 118 allows irrigation fluid to flow into the space 108 between the support catheter 102 and the aspiration catheter 104. The manifold 118 also includes a passage 122 extending for the aspiration catheter 104 to connect to a vacuum source.

[0082] The passage 122 may include a sealing member 124 to prevent the irrigation fluid from flowing out of the space outside the suction catheter 104. The sealing member 124 can provide contact with the suction catheter 104 at less than 360 degrees. For example, the sealing member 124 may have one or more protrusions or branches, such as two, three, or four protrusions, to form a boundary with the suction catheter 104. The separate contact points reduce the amount of friction between the suction catheter 104 and the sealing member 124, allowing the use of a lower torque motor.

[0083] The internal suction catheter 104 can be moved manually or automatically within the lumen of the support catheter. When automated, the catheter assembly 100 may include a drive unit 126. The drive unit 126 may include a motor for driving the suction catheter 104 relative to the support catheter 102. The drive unit 126 may include, or be operably connected to, a controller configured to cause the motor to advance and retract the suction catheter. The drive unit 126 may include a battery source. The drive unit 126 may be a handheld component that can be separately attached to the suction catheter 104. For example, the same drive unit 126 can be used with a disposable catheter assembly.

[0084] Figure 13A shows the catheter assembly 100 in the closed position with the suction catheter 104 retracted into the valve 112. In this configuration, an irrigation fluid (e.g., saline solution) flows through the catheter assembly 100 to lubricate the system, and a vacuum builds up at the distal end of the catheter assembly 100.

[0085] As the suction catheter 104 advances (see Figure 13B), the valve 112 opens outward. The valve 112 can be made from a material that forms a seal with the suction catheter 104, preventing the irrigation fluid from flowing out of the support catheter 102. When the valve 112 opens, the accumulation of vacuum increases the engagement between the blood clot C and the suction catheter 104.

[0086] The operation of moving a blood clot toward the catheter opening is performed by inducing a flow field that generates force on the blood clot in the direction of the catheter opening. However, there is a fundamental physical limit to the maximum vacuum level that can be accumulated in the vascular structure, which is 1 bar. Conventional aspiration devices rely on high blood flow to move the blood clot toward the catheter, but blood flow is insufficient in various regions of the vascular structure to achieve sufficient aspiration. Unlike conventional systems, the catheter assembly 100 minimizes its dependence on flow velocity. The catheter assembly 100 accumulates pressure at its distal end such that the absolute pressure is at least about 25 inHg and / or about 35 inHg or less, for example, at least about 26 inHg and / or about 33 inHg or less, when the valve 112 is open (see Figure 15B). The absolute pressure at the distal end of the catheter assembly 100 can be at least about 15 inHg, at least about 20 inHg, at least about 25 inHg, at least about 30 inHg, or at least about 35 inHg when the valve 112 is open. This creates a sufficient flow field to move the blood clot C toward the aspiration catheter 104. Furthermore, moving the aspiration catheter 104 distally toward the blood clot C facilitates the acquisition of the blood clot.

[0087] As the suction catheter 104 is retracted, it engages sufficiently with the blood clot C to draw it into the support catheter 102. The pushing force can be increased by adding a hydraulic column, as will be discussed later with respect to Figure 13E. When the suction catheter 104 is retracted proximal to the valve 112, the valve 112 closes. As shown in Figures 13C and 13D, the valve housing 110 breaks up the blood clot C, and the valve 112 cuts the blood clot C into fragments. The valve 112 can improve the fragmentation, either alone or in combination with the valve housing 110.

[0088] In conventional systems, the length of the blood clot within the catheter and the increased friction against the wall create resistance to suction, leading to blockages. To reduce the length of the blood clot, the catheter assembly 100 cuts the clot at the distal tip 114 of the valve housing 110 and / or the valve 112. The combination of the vacuum force on one side of the thrombus C and the shear force of the catheter assembly 100 on the thrombus C causes fragmentation. This step utilizes the clot's vulnerability to shear force to reduce its length and minimize friction.

[0089] The steps shown in Figures 13A to 13D are repeated until the entire blood clot C is aspirated. The steps can be repeated at least twice per second, at least three times per second, at least four times per second, at least five times per second, at least six times per second, at least seven times per second, at least eight times per second, at least nine times per second, or at least ten times per second.

[0090] During this process, positive pressure can be applied to the suction lumen 106. For example, as shown in Figure 13E, the irrigation fluid can flow periodically or continuously. This helps to push the macerated blood clots through the suction catheter 104 and out into the container 170. Furthermore, the irrigation prevents the formation of air bubbles within the catheter assembly 100.

[0091] As shown in Figure 13E, the fluid flows between the outer surface of the suction catheter 104 and the inner surface of the support catheter 102. When the irrigation fluid reaches the valve 112, it enters the distal end of the suction catheter 104, and the vacuum force pushes the macerated blood clot segment proximal through the suction catheter 104 as it aspirates the blood clot segment. By applying water pressure, the vacuum force can be doubled to at least about 1 bar and / or about 2 bar or less. Adding propellant speeds up suction and prevents clogging. Positive pressure can also be applied by other means, such as using a pump.

[0092] If the suction catheter 104 becomes blocked, it can be retracted proximal to the valve 112 without completely withdrawing it from the body. This increases the suction of the irrigation fluid. The perfusion will clear the blockage in the suction catheter 104. In some methods, perfusion can be activated only when discontinuous flow (blockage) is detected, or perfusion can be increased when discontinuous flow is detected. During this process, the suction catheter 104 may remain stationary, or it may advance and be retracted while remaining behind the distal valve 112.

[0093] Figures 15A and 15B show typical records of vacuum pressure filling and release at the distal tip of the suction catheter 104 when the flow stops (Figure 13A) and restarts (Figure 13B).

[0094] term This specification describes specific suction catheter systems and methods, along with dual catheter systems having a support catheter and an internal suction catheter. However, the principles of the systems and methods described herein are also applicable to single catheter systems having different types of valves, such as automatic valves. Furthermore, while the support catheter and the internal suction catheter provide coaxial irrigation and suction lumens, other configurations are possible, such as separate, non-coaxial lumens.

[0095] As used herein, the relative terms “proximal” and “distal” are defined in terms of the catheter system. Thus, proximal refers to the direction of the handle, and distal refers to the direction of the suction tip.

[0096] Terms such as "include," "contain," and "possess" are synonymous and are used comprehensively and expansively, without excluding further components, features, functions, or actions. The term "or" is also used in a comprehensive sense (rather than an exclusive sense), and when used to connect a list of components, for example, "or" means one, some, or all of the components in the list.

[0097] While specific embodiments and examples are described herein, it will be understood by those skilled in the art that many aspects of the delivery systems shown and described herein may be combined and / or modified in different ways to form further embodiments or acceptable examples. All such modifications and variations are intended to be included within the scope of this disclosure. A wide variety of designs and approaches are possible. Features, structures, or steps disclosed herein are not essential or indispensable.

[0098] For the purposes of this disclosure, specific embodiments, advantages, and novel features are described herein. It should be understood that not all such advantages can necessarily be achieved according to any particular embodiment. Thus, a person skilled in the art will recognize that, for example, this disclosure can be implemented or carried out in a manner that obtains one or more advantages as taught herein, but not necessarily other advantages as may be taught or suggested herein.

[0099] Furthermore, while exemplary embodiments are described herein, the scope of any and all embodiments having equivalent components, modifications, omissions, combinations (e.g., combinations of aspects across various embodiments), alterations, and / or variations will be understood by those skilled in the art based on this disclosure. The matters of the claims should be understood broadly based on the language used in the claims and not limited to the examples described herein or at the time of filing, and such examples should be construed as non-exclusive. Furthermore, the operations in the disclosed processes and methods can be modified in any way, including changing the order of operations, and / or inserting additional operations, and / or deleting operations. Thus, it is intended that the specification and examples are considered only as examples, and the true scope and spirit are indicated by the entire scope of the claims and their equivalents.

[0100] In particular, conditional language used herein, such as “can,” “could,” “may,” and “for example,” is intended to mean, in general, that some embodiments include certain features, components, and / or states, while others do not, unless otherwise stated or understood in the context in which they are used. Therefore, such conditional language is not intended to suggest, in general, that features, components, blocks, and / or states are required in any way to one or more embodiments, or that one or more embodiments necessarily include logic that determines whether these features, components, and / or states are included or implemented in any particular embodiment, with or without information or instructions from the authors.

[0101] Furthermore, the scope disclosed herein includes all overlaps, sub-scopes, and combinations thereof. Words such as “maximum,” “minimum,” “greater than,” “less than,” and “between” include the stated numbers. Numbers preceded by terms such as “about” or “approximately” include the stated numbers and should be interpreted on a case-by-case basis (e.g., as accurately as reasonably possible under the circumstances, e.g., ±1%, ±5%, ±10%, ±15%). For example, “about 1.0 mm” includes “1.0 mm.”

Claims

1. A suction catheter assembly for removing blood clots, A long tubular body, and a support catheter including a valve at the distal end of the support catheter, A suction catheter configured to communicate with a vacuum source, comprising a suction catheter disposed within the support catheter, movable relative to the support catheter, and including a suction lumen for receiving at least a portion of the blood clot, The distal end of the suction catheter is configured to repeatedly advance distally and retract proximally relative to the distal end of the support catheter. When the distal end of the suction catheter advances distal to the valve, the valve opens. When the distal end of the suction catheter is retracted proximal to the valve, the valve closes. A suction catheter assembly wherein the distal end of the support catheter includes a cut shoulder portion configured to separate at least a portion of the blood clot from the blood clot while drawing out at least a portion of the blood clot through the valve.

2. The suction catheter assembly according to claim 1, wherein the valve controls the level of vacuum pressure at the distal end of the suction catheter assembly.

3. The aspiration catheter assembly according to claim 1, wherein the valve prevents the irrigation fluid from flowing out of the support catheter.

4. The suction catheter assembly according to claim 1, wherein the support catheter includes a valve housing fixed to the distal end of the long tubular body, and the valve is disposed within the valve housing.

5. The suction catheter assembly according to claim 4, wherein the distal end of the valve housing is the distal end of the support catheter.

6. The suction catheter assembly according to claim 4, wherein the distal end of the valve housing is tapered.

7. The suction catheter assembly according to claim 4, wherein the valve housing is located radially outward of the elongated tubular body.

8. The suction catheter assembly according to claim 1, wherein the valve is a duckbill valve.

9. The suction catheter assembly according to claim 1, further comprising a manifold at the proximal end of the support catheter, wherein the suction catheter extends proximal to the manifold for connection to the vacuum source.

10. The suction catheter assembly according to claim 9, wherein the manifold includes an inlet for the irrigation fluid.

11. The suction catheter assembly according to claim 9, wherein the manifold includes a seal for the suction catheter.

12. A motor operably connected to the aforementioned suction catheter, The suction catheter assembly according to claim 1, further comprising a controller configured to advance and retract the suction catheter relative to the valve of the support catheter.

13. The suction catheter assembly according to claim 1, wherein the working length of the suction catheter is at least as long as the working length of the support catheter.

14. The suction catheter assembly according to claim 1, wherein the working length of the suction catheter is less than the working length of the support catheter.

15. The suction catheter assembly according to claim 1, wherein the movement of the suction catheter is restricted relative to the support catheter.

16. The suction catheter assembly according to claim 1, wherein the space between the suction catheter and the support catheter is sealed to prevent the flow of fluid through the space.

17. The suction catheter assembly according to claim 1, further comprising a space between the suction catheter for perfusion and the support catheter.

18. The suction catheter assembly according to claim 1, further comprising a stopper mechanism configured to prevent the distal end of the suction catheter from moving beyond a predetermined distance from the distal end of the support catheter.

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