Suction catheter system and method of use

Abstract

A coaxial catheter system (150) has a catheter (200) and a catheter advancement element (300) located coaxially within a lumen of a distal portion of the catheter. The catheter advancement element includes a tip portion (346) that tapers and has different flexibility along its longitudinal axis. A system includes a coaxial catheter system, a guide sheath (400), and a vacuum source.

Description

[0001] This application is a divisional application of the patent application for invention with the application number 201980047301.0, the application date of May 16, 2019, and the invention title of "Suction Catheter System and Method of Use".

[0002] Cross - reference to related applications

[0003] This application claims the benefit of the priority of co - pending U.S. Provisional Patent Application Serial No. 62 / 673,009, filed on May 17, 2018. The entire disclosure of this provisional application is incorporated herein by reference. Technical field

[0004] This technology generally relates to medical devices and methods, and more particularly to a suction catheter system and its method of use. Background art

[0005] Acute ischemic stroke (AIS) typically occurs when an artery leading to the brain becomes blocked, preventing the delivery of fresh oxygenated blood from the heart and lungs to the brain. These blockages are usually caused by a thrombus or embolus lodging in an artery and obstructing the artery that supplies blood to a region of brain tissue. If the artery is blocked, ischemic damage then occurs, and brain cells may stop functioning. Additionally, if the artery remains blocked for more than a few minutes, brain cells may die, resulting in permanent neurological deficits or death. Therefore, immediate treatment is crucial.

[0006] Two main therapies are used to treat ischemic stroke: thrombolytic therapy and endovascular therapy. The most common treatment for restoring blood flow or reperfusing the stroke area is the use of intravenous (IV) thrombolytic therapy. The time window for implementing thrombolytic therapy is within 3 hours (4.5 hours for some patients) after the onset of symptoms by intravenous infusion, or within 6 hours for intra - arterial infusion at a fixed point. Treating at a later time has not been shown to provide a proven benefit and may subject the patient to a greater risk of bleeding due to the thrombolytic effect. Endovascular treatment most commonly uses a set of tools to mechanically remove the embolus without using thrombolytic therapy.

[0007] The scope of endovascular treatment includes mechanical thrombectomy and aspiration techniques. Mechanical thrombectomy utilizes retrievable structures such as coil - based retrievable stents (also known as stent retrievers or STENTRIEVERs), braided wire stents, or laser - cut stents with struts. These stents can be opened within the clot in the brain anatomy to engage the clot with the stent struts, forming a channel in the embolism to restore a certain blood flow, and then retrieved by pulling the retrievable structure out of the anatomy. Other endovascular techniques for mechanically removing AIS - related emboli include manual aspiration thrombectomy (MAT) (also known as the "ADAPT" technique). ADAPT / MAT is an endovascular procedure where a large - bore catheter is inserted through the femoral artery and maneuvered through complex anatomy until the level of the embolus, which may be in the extracranial carotid artery, vertebral artery, or intracranial artery. The aspiration technique can be used to remove emboli through the large - bore catheter. Another endovascular procedure is STENTRIEVER - mediated manual aspiration thrombectomy (SMAT) (similar to the STENTRIEVER - assisted "Solumbra" technique). SMAT is similar to MAT and involves accessing the embolus through the femoral artery. However, after access is achieved, the embolus is pulled back into the large - bore catheter using a retrievable structure.

[0008] To access the brain anatomy, a guiding catheter or guiding sheath is used to direct the interventional device from the arterial access site (usually the femoral artery) to the target anatomy. The length of the guide is determined by the distance between the access site and the desired location of the distal tip of the guide. Interventional devices for sub - selective guidance and aspiration (such as guidewires, microcatheters, and intermediate catheters) are inserted through the guide and advanced to the target site. Typically, the devices are used in a coaxial manner, i.e., the guidewire inside the microcatheter inside the intermediate catheter is advanced step - by - step as a component with the least invasive element inside to the target site, first advancing distally and providing support for the advancement of the outer elements. The length of each element of the coaxial assembly takes into account the length of the guide, the length of the proximal connector on the catheter, and the length required to extend distally.

[0009] For example, a typical triaxial system for aspirating or delivering stent retrievers and other interventional devices requires a series of overlapping catheters, each catheter having its own rotational hemostatic valve (RHV) at the proximal end. For example, a guidewire can be inserted through a Penumbra Velocity microcatheter having a first proximal RHV, the Penumbra Velocity microcatheter can be inserted through a Penumbra ACE68 having a second proximal RHV, and the Penumbra ACE68 can be inserted through a Penumbra NeuronMAX 088 access catheter having a third proximal RHV located in the cervical carotid artery via a femoral introducer. Maintaining the coaxial relationship between these catheters can be technically challenging. The three RHVs must be continuously adjusted, either with two hands or more commonly with four hands (i.e., two operators). In addition, the working area for a typical triaxial system for aspiration and / or intracranial device delivery may require a working area of 3 - 5 feet at the bottom of the operating table.

[0010] The time required to access the occluded site and restore (even partially) blood flow to the vessel is critical for determining the successful outcome of such procedures. Similarly, the occurrence of distal embolization during the procedure, as well as potential negative neurological effects and surgical complications such as perforation and intracerebral hemorrhage, limit the success of the procedure. There is a need for a system and method of a device that allows for rapid access, optimized catheter aspiration, and treatment to fully restore blood flow to the occluded cerebral blood vessel. Summary of the Invention

[0011] In one aspect, a coaxial catheter system is described that includes a catheter and a catheter advancement element. The catheter includes: a distal catheter portion having a lumen and a distal end with an opening from the lumen, the lumen having an inner diameter of at least about 0.052” at the distal end; and a proximal extension that is coupled to the distal catheter portion and extends proximally from the distal catheter portion, the proximal extension being less flexible than the distal catheter portion. The catheter advancement element includes: a tubular portion having an outer diameter and an inner diameter of at least about 0.014” to about 0.024”, the outer diameter having at least one engagement point. The difference between the inner diameter of the distal catheter portion and the outer diameter of the tubular portion at the engagement point is no greater than about 0.010”. The catheter advancement element includes a proximal extension that is coupled to the tubular portion and extends proximally from the tubular portion, the proximal extension being less flexible than the tubular portion. The tip is located distally of at least one engagement point of the tubular portion. The tip has a length and tapers along at least a portion of the length of the tip. The coaxial catheter system has an advancement configuration characterized in that: the catheter advancement element is coaxially located within the lumen of the distal catheter portion, and at least one engagement point of the tubular portion is substantially aligned with the distal end of the distal catheter portion. The advancement configuration is further characterized in that, in the advancement configuration, the tip has at least three points spaced along the length of the tip. The at least three points include a distal point among the at least three points, the distal point being positioned proximally a distance from the most distal end of the catheter advancement element, the distal point having a first bending force of no greater than about 0.05 Newtons. An intermediate point among the at least three points is positioned proximally a distance from the distal point, the intermediate point having a second bending force; a proximal point among the at least three points is positioned proximally a distance from the intermediate point, the proximal point having a third bending force. The advancement configuration is further characterized in that the coaxial system has at least two system points along the length of the coaxial system. The at least two system points include: a first system point among the at least two system points, which is positioned near the distal end of the catheter portion, the first system point having a first system bending force; and a second system point among the at least two system points, which is positioned distally of the first system point at a distance of at least about 1 mm distally of the distal end of the catheter portion, wherein the second system point can be the same as or different from the proximal point, and the second system point having a second system bending force.

[0012] The difference between the second bending force and the first bending force divided by the distance between the distal point and the intermediate point may be equal to a first flexure slope. The difference between the third bending force and the second bending force divided by the distance between the intermediate point and the proximal point may be equal to a second flexure slope. The average of the first flexure slope and the second flexure slope may define an average tip flexure slope. The difference between the first system bending force and the second system bending force divided by the distance between the first system point and the second system point may be equal to a third flexure slope. The ratio of the third flexure slope to the average tip flexure slope may be less than about 25.

[0013] The proximal extension of the catheter advancement element may have at least one stiffness point located within about 125 cm from the distalmost end of the catheter advancement element, and the at least one stiffness point has a bending force. The ratio of the bending force of the at least one stiffness point to the first bending force of the distal point may be at least about 100. The proximal extension of the catheter advancement element may have at least one stiffness point located within about 125 cm from the distalmost end of the catheter advancement element, the at least one stiffness point has a bending force, wherein the ratio of the bending force of the at least one stiffness point to the first bending force of the distal point is at least about 200. The proximal extension of the catheter advancement element may have at least one stiffness point located within about 125 cm from the distalmost end of the catheter advancement element, and the at least one stiffness point has a bending force. The ratio of the bending force of the at least one stiffness point to the first bending force of the distal point may be greater than at least about 300. The length of the tip portion may be at least about 1 cm to about 4 cm. The ratio of the third bending force of the proximal point to the first bending force of the distal point may be at least 2. The ratio of the first system bending force to the first bending force of the distal point may be at least 2. The distal catheter portion may have a catheter point located at least 5 mm proximally from the distal end, and the catheter point has a catheter bending force. The first bending force of the distal point may be about 5%-15% of the catheter bending force. The third bending force of the proximal point may be about 50%-90% of the catheter bending force. The difference between the first bending force at the distal point and the third bending force at the proximal point may be a function of the wall thickness. The inner diameter at the distal end of the distal catheter portion may be about 0.054", and the difference at the fitting point may be about 0.006" to about 0.008". The inner diameter at the distal end of the distal catheter portion may be about 0.070" to about 0.088", and the difference at the fitting point may not be greater than about 0.006" to about 0.008".

[0014] The tubular portion of the catheter advancement element may have a radiopaque marker band that is embedded within the wall of the tubular portion or located above the wall of the tubular portion, and the radiopaque marker band is located at the fitting point. The radiopaque marker band may have a proximal edge, a distal edge, and a width between the proximal edge and the distal edge. When in the advancement configuration, the proximal edge of the radiopaque marker band may be substantially aligned with the distal end of the distal catheter portion such that the radiopaque marker band remains outside the lumen of the distal catheter portion. The outer diameter of the tubular portion may have a length of at least about 5 cm to about 10 cm. The fitting point may be located along at least a portion of the length. The outer diameter may be substantially uniform along the length. The outer diameter may not be substantially uniform along the length. The distal point may be located at least 5 mm proximally from the distalmost end of the catheter advancement element. The first system point may be located at least about 5 mm proximally from the distal end of the catheter portion.

[0015] In a related aspect, a coaxial catheter system is described that includes a catheter and a catheter advancement element. The catheter includes a distal catheter portion having a lumen and a distal end with an opening from the lumen, the lumen having an inner diameter of at least about 0.052” at the distal end. The catheter includes a proximal extension that is coupled to the distal catheter portion and extends proximally from the distal catheter portion, the proximal extension being less flexible than the distal catheter portion. The catheter advancement element includes a tubular portion having an outer diameter and an inner diameter of at least about 0.014” to about 0.024”. The outer diameter has at least one engagement point. The difference between the inner diameter of the distal catheter portion and the outer diameter of the tubular portion at the engagement point is no greater than about 0.010”. The catheter advancement element includes a tip portion that is located distally of at least one engagement point of the tubular portion. The tip portion has a length and tapers along at least a portion of the length of the tip portion. The tip portion has a distal point that is positioned at least 5 mm proximally from the most distal end of the catheter advancement element, the distal point having a bending force of no greater than about 0.05 Newtons.

[0016] In a related aspect, a method of performing a medical procedure in a patient's cerebrovascular vessel is described. The method includes advancing a first assembled coaxial system of a device toward an occlusion within the cerebrovascular vessel. The first assembled coaxial system of the device includes a first catheter having a first catheter portion with a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end. A first proximal extension is coupled to the first catheter portion and extends proximally from the first catheter portion, the first proximal extension being less flexible than the first catheter portion. The first assembled coaxial system of the device includes a first delivery element having a flexible elongate body and a soft tapered distal tip. At least a portion of the elongate body is located within the lumen of the first catheter portion, and the tapered distal tip extends distally beyond the distal end of the first catheter portion. The method includes withdrawing the first delivery element proximally from the lumen of the first catheter portion and advancing a second assembled coaxial system of the device through the lumen of the first catheter portion, out the distal opening of the lumen, and to a position adjacent to the proximal face of the occlusion within the cerebrovascular vessel. The second assembled coaxial system of the device includes a second catheter and a second delivery element. The second catheter includes: a second catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a second proximal extension coupled to the second catheter portion and extending proximally from the second catheter portion, the second proximal extension being less flexible than the second catheter portion. The second delivery element includes a flexible elongate body and a soft tapered distal tip, at least a portion of the elongate body being located within the lumen of the second catheter portion, and the tapered distal tip extending distally beyond the distal end of the second catheter portion. After the distal end of the second catheter portion is distal to the petrous portion of the internal carotid artery, the second assembled coaxial system of the device is advanced together. The method includes withdrawing the second delivery element proximally from the lumen of the second catheter portion; applying a suction pressure through the lumen of the second catheter portion; anchoring the distal end of the second catheter portion to the occlusion by the suction pressure; and applying a proximally directed force on the second catheter while the distal end of the second catheter portion remains anchored to the occlusion to reduce slack of the second catheter relative to the surrounding anatomy.

[0017] The method may further include withdrawing the second catheter from the cerebrovascular vessel, the distal end of the second catheter portion having occlusive material attached thereto. The method may further include advancing the first catheter over the second catheter while anchoring the distal end of the second catheter portion to the occlusion by the suction pressure. The method may further include positioning the distal end of the first catheter portion adjacent to the proximal face of the occlusion. The method may further include withdrawing the second catheter into the lumen of the first catheter; and automatically applying a suction pressure through the lumen of the first catheter portion when the second catheter is withdrawn into the lumen. The suction pressure applied through the lumen of the first catheter portion and the lumen of the second catheter portion may be applied from a single suction source. The distal end of the second catheter portion may be attached with occlusive material.

[0018] The method may further include withdrawing a second catheter from the lumen of a first catheter while maintaining a suction pressure through the lumen of the first catheter portion. The method may further include advancing a guide sheath from a passage position, wherein the guide sheath includes a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. Advancing the first assembled coaxial catheter system may include advancing the first assembled coaxial catheter system through the guide sheath. The first catheter portion may have an outer diameter configured to seal with the central lumen of the guide sheath when suction pressure is applied. The second catheter portion may have an outer diameter configured to seal with the lumen of the first catheter when suction pressure is applied. The outer surface of the second catheter portion may seal with the inner surface of the first catheter portion, thereby forming an adjoining lumen between the distal opening of the second catheter portion and the proximal end of the guide sheath. The connector may include a single-headed or double-headed rotary hemostatic valve. Both the first assembled coaxial catheter system and the second assembled coaxial catheter system may be advanced through the connector. Advancing the guide sheath includes advancing the distal opening of the guide sheath to a position in the distal internal carotid artery (ICA). The inner diameter of the second catheter may be between 0.054” and 0.070”, the inner diameter of the first catheter may be between 0.072” and 0.088”, and the guide sheath may be between 6Fr and 8Fr. The method may further include advancing a guide wire through the occlusion. The occlusion need not be penetrated during the method. The first assembled coaxial catheter system may further include a guide wire. At the time of assembly, the guide wire may be positioned within the lumen of the flexible elongate body of the first delivery element, and the first delivery element may be positioned within the lumen of the first catheter portion such that the tapered distal tip extends distally beyond the distal end of the first catheter portion and the guide wire extends distally beyond the tapered distal tip. The outer surface of the second catheter portion may seal with the inner surface of the first catheter portion, thereby forming an adjoining lumen between the distal opening of the second catheter portion and the proximal opening of the first catheter portion.

[0019] In a related aspect, a method of performing a medical procedure in a patient's cerebrovascular vessel is described. The method includes advancing a first assembled coaxial catheter system to a position near the proximal side of an occlusion within the cerebrovascular vessel. The first assembled coaxial catheter system includes a first catheter and a first delivery element. The first catheter includes: a first catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a first proximal extension coupled to the first catheter portion and extending proximally from the first catheter portion, the first proximal extension being less flexible than the first catheter portion. The first delivery element includes a flexible elongated body and a soft tapered distal tip, at least a portion of the elongated body being located within the lumen of the first catheter portion, and the tapered distal tip extending distally beyond the distal end of the first catheter portion. After the distal end of the first catheter portion is distal to the petrous portion of the internal carotid artery, the first assembled coaxial system of the device is advanced together. The method includes retracting the first delivery element proximally from the lumen of the first catheter portion; applying a suction pressure through the lumen of the first catheter portion; anchoring the distal end of the first catheter portion to the occlusion by the suction pressure; applying a proximally directed force on the first catheter while maintaining the distal end of the first catheter anchored to the occlusion to reduce slack of the first catheter relative to the surrounding anatomy; and advancing a second catheter over the first catheter while anchoring the distal end of the first catheter portion to the occlusion by the suction pressure. The second catheter includes a second catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a second proximal extension coupled to the second catheter portion and extending proximally from the second catheter portion. The second proximal extension is less flexible than the second catheter portion.

[0020] The method may further include withdrawing the first catheter from the cerebral blood vessel. The distal end of the first catheter portion may have an attached occlusive material. The method may further include positioning the distal end of the second catheter portion adjacent to the proximal side of the occlusion. The method may further include withdrawing the first catheter into the lumen of the second catheter; and automatically applying a suction pressure through the lumen of the second catheter portion when the first catheter is withdrawn into the lumen. The suction pressure that may be applied through the lumen of the first catheter portion and the lumen of the second catheter portion is applied from a single suction source. The distal end of the first catheter may have an attached occlusive material. The method may further include withdrawing the first catheter from the lumen of the second catheter while the second catheter maintains a suction pressure through the lumen of the second catheter portion. The method may further include advancing a guide sheath from a passage position. The guide sheath may include a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. The second catheter portion may include an outer diameter configured to seal with the central lumen of the guide sheath when a suction pressure is applied. The first catheter portion may have an outer diameter configured to seal with the lumen of the second catheter when a suction pressure is applied. The outer surface of the first catheter portion may seal with the inner surface of the second catheter portion such that an adjoining lumen is formed between the distal opening of the first catheter portion and the proximal end of the guide sheath. The connector may include a single- or double-headed rotary hemostatic valve. Both the first assembled coaxial catheter system and the second catheter may be advanced through the connector.

[0021] The method may include: advancing the guide sheath includes advancing the distal opening of the guide sheath to a position in the distal internal carotid artery (ICA). The inner diameter of the first catheter may be between 0.054” and 0.070”. The inner diameter of the second catheter may be between 0.072” and 0.088”. The guide sheath may be between 6Fr and 8Fr. The method may further include advancing a guide wire through the occlusion. It is not necessary to penetrate the occlusion during the method. The inner surface of the second catheter portion may seal with the outer surface of the first catheter portion such that an adjoining suction lumen is formed between the distal opening of the first catheter portion and the proximal opening of the second catheter portion.

[0022] In a related aspect, a system for a device to perform a medical operation in a patient's cerebrovascular vessel is disclosed. The system includes a first catheter and a second catheter. The first catheter includes: a first catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening into the lumen, and a distal end; and a first proximal extension coupled to the first catheter portion and extending proximally from the first catheter portion, the first proximal extension being less flexible than the first catheter portion. The second catheter is configured to be disposed coaxially within the lumen of the first catheter portion. The second catheter includes a second catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a second proximal extension coupled to the second catheter portion and extending proximally from the second catheter portion, the second proximal extension being less flexible than the second catheter portion. The system includes a guiding sheath having a tubular sheath body having a central lumen, a proximal end, a distal opening, and a connector operably connected to the proximal end of the sheath body. A single shared vacuum source is coupled to the connector of the guiding sheath and is configured to apply a suction pressure through the central lumen of the guiding sheath, the lumen of the first catheter portion, and the lumen of the second catheter portion. The outer surface of the second catheter portion is sealable with the inner surface of the first catheter portion to form an adjoining lumen between the distal opening of the first catheter portion and the proximal opening of the second catheter portion.

[0023] In a related aspect, a method for performing a medical operation in a patient's cerebrovascular vessel is disclosed. The method includes advancing a first catheter toward an occlusion within the cerebrovascular vessel. The first catheter includes: a first catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a first proximal extension coupled to the first catheter portion near the proximal opening, the first proximal extension being less flexible than the first catheter portion. The method includes advancing a second catheter through the lumen of the first catheter portion, exiting through the distal opening of the lumen, and reaching a position near the proximal side of the occlusion within the cerebrovascular vessel. The second catheter includes: a second catheter portion having a lumen, a proximal opening leading to the lumen, a distal opening from the lumen, and a distal end; and a second proximal extension coupled to the second catheter portion near the proximal opening, the second proximal extension being less flexible than the second catheter portion. The method includes forming a seal between the outer diameter of the second catheter portion and the inner diameter of the first catheter portion; and applying a suction pressure through at least one of the lumen of the second catheter portion, the lumen of the first catheter portion, or an adjoining suction lumen formed by the lumen of the first catheter portion and the lumen of the second catheter portion. The adjoining suction lumen extends from the distal end of the second catheter portion toward the proximal opening of the first catheter portion. The method may further include anchoring the distal end of the second catheter portion to the occlusion by the suction pressure. The method may further include applying a proximally directed force on the second catheter while the distal end of the second catheter portion remains anchored to the occlusion to reduce slack of the second catheter relative to the surrounding anatomy.

[0024] In some variations, one or more of the following methods can optionally be included in any feasible combination of the above methods, devices, apparatuses, and systems. More details of the methods, devices, apparatuses, and systems are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the specification and the drawings. Description of the Drawings

[0025] These and other aspects will now be described in detail with reference to the following drawings. Generally, the drawings are not drawn to absolute or relative scale but are for illustrative purposes. Also, for clarity of illustration, the relative positions of features and elements may be modified.

[0026] Figures 1A to 1B Shows the route from the end of the internal carotid artery to the cerebral blood vessels;

[0027] Figure 1C Shows the aortic arch, which includes the origins of the brachiocephalic trunk BT, left common carotid artery LCC, and left subclavian artery LSA leading from the aortic arch AA;

[0028] Figure 2A Is an exploded view of an embodiment of a suction catheter system;

[0029] Figure 2B Is Figure 2A An assembled view of the suction catheter system;

[0030] Figure 2C Is a detail view taken at the C-C circle of Figure 2A ;

[0031] Figure 2D Shows an embodiment of an arterial access device with a distal occlusion balloon;

[0032] Figure 3 Is a side view of an embodiment of a spiked distal access catheter;

[0033] Figure 4A Is a cross-sectional view of a first embodiment of the proximal control element of a spiked distal access catheter;

[0034] Figure 4B Is a cross-sectional view of another embodiment of the proximal control element of a spiked distal access catheter;

[0035] Figure 4C Is of Figure 4A in the working lumen of the access sheath;

[0036] Figure 4D Is a cross-sectional view of Figure 4B in the working lumen of the access sheath with a catheter advancement element extending therethrough;

[0037] Figure 4E is a comparison Figure 4A of the proximal control element and Figure 4D in the working lumen of the access sheath of Figure 4B a schematic cross-sectional view of the surface area of the proximal control element of

[0038] Figures 4F - 4G are schematic cross-sectional views comparing the trapezoidal proximal extension and the D-shaped proximal extension relative to the working lumen of the access sheath, respectively;

[0039] Figure 5A is a side view of an embodiment of a spiked distal access catheter;

[0040] Figure 5B is Figure 5A a top view of the spiked distal access catheter of

[0041] Figure 5C is along Figure 5B a cross-sectional view of the spiked distal access catheter taken along line C-C of

[0042] Figure 5D is along Figure 5B a cross-sectional view of the spiked distal access catheter taken along line D-D of

[0043] Figures 5E - 5F is Figure 5A a partial perspective view of the spiked distal access catheter of

[0044] Figure 6A is a side view of an embodiment of a spiked distal access catheter;

[0045] Figure 6B is Figure 6A a top view of the spiked distal access catheter of

[0046] Figure 6C is along Figure 6B a cross-sectional view of the spiked distal access catheter taken along line C-C of

[0047] Figure 6D is along Figure 6B a cross-sectional view of the spiked distal access catheter taken along line D-D of

[0048] Figures 6E - 6F is Figure 6A a partial perspective view of the spiked distal access catheter of

[0049] Figure 7A is a side view of an embodiment of a catheter advancement element;

[0050] Figure 7B is Figure 7ACross-sectional view of the catheter advancement element;

[0051] Figure 7C is taken along the C-C circle Figure 7B Detail view of;

[0052] Figure 7D Side view of another embodiment of the catheter advancement element;

[0053] Figure 7E is Figure 7D Cross-sectional view of an embodiment of the proximal portion of the catheter advancement element;

[0054] Figures 7F - 7J is for connection to Figure 7E Various views of an embodiment of the proximal hub for the proximal portion shown;

[0055] Figure 8A Side view of an embodiment of the catheter;

[0056] Figure 8B is Figure 8A Schematic cross-sectional view of the distal region of the catheter;

[0057] Figure 8C is Figure 8A Schematic cross-sectional view of the distal region of the catheter;

[0058] Figures 9A - 9C Various views of the proximal extension connector;

[0059] Figure 10A Schematic cross-sectional view of an embodiment of the catheter advancement element;

[0060] Figure 10B is Figure 10A Schematic cross-sectional view of the distal region of the catheter advancement element;

[0061] Figure 10C is Figure 10A Schematic cross-sectional view of the intermediate region of the catheter advancement element;

[0062] Figure 11 Schematic diagram of an embodiment of a catheter aligned with an embodiment of the catheter advancement element, showing staggered material transitions;

[0063] Figure 12 Schematic diagram of an embodiment of a bending force test system;

[0064] Figure 13A Schematic diagram of the distal region of the catheter advancement element extending through the catheter and the point for bending force testing;

[0065] Figure 13BShows the bending force (in Newtons (N)) along the length of a catheter system, which includes a catheter and a catheter advancement element in a deployed configuration (dashed line), a separate catheter advancement element (dotted line), and a separate catheter (solid line);

[0066] Figure 14A Is a graph of the bending force along the length of a catheter system formed by a catheter advancement element configured to extend through a catheter with an inner diameter of 0.054”;

[0067] Figure 14B Is a graph of the bending force along the length of a catheter system formed by a catheter advancement element configured to extend through a catheter with an inner diameter of 0.070”;

[0068] Figure 14C Is a graph of the bending force along the length of a catheter system formed by a catheter advancement element configured to extend through a catheter with an inner diameter of 0.070”;

[0069] Figure 14D Is a graph of the bending force along the length of a catheter system formed by a catheter advancement element configured to extend through a catheter with an inner diameter of 0.088”;

[0070] Figure 14E Is a graph of the bending force along the length of another catheter system;

[0071] Figure 15 Shows an embodiment of a nested catheter system.

[0072] It should be understood that the figures are merely exemplary and are not meant to be drawn to scale. It should be understood that the devices described herein may include features that are not necessarily depicted in each figure. Detailed Description

[0073] Navigating the carotid artery anatomy to treat various neurovascular lesions at the cerebral artery level such as acute ischemic stroke (AIS) requires a catheter system with superior flexibility and deliverability. The internal carotid artery (ICA) originates from the bifurcation of the common carotid artery (CCA) at the disc level between the C3 and C4 vertebrae. As Figure 1AAs shown, the course of the ICA is divided into four parts - the cervical Cr part, the petrous Pt part, the cavernous Cv part, and the cerebral Cb part. In the anterior circulation, the terminal part of the continuous tortuous carotid artery is locked in its position by bone elements. The carotid Cr enters the petrous bone and is locked within a set of turns while being enclosed within the bone. The cavernous carotid artery is an artery that passes through the venous bed, the cavernous sinus. Although it is flexible, it is locked by another bone element when it exits the cavernous sinus, and this other bone element surrounds and secures the entrance into the cranial cavity. Due to these bony fixation points, the petrous and cavernous carotid arteries (Pt and Cv) and above are relatively consistent in terms of their tortuosity. The carotid siphon CS is the S-shaped part at the terminal end of the ICA. The carotid siphon CS begins at the posterior bend of the cavernous ICA and ends at the point where the ICA branches into the anterior cerebral artery ACA and the middle cerebral artery MCA. The ophthalmic artery originates from the cerebral ICA and represents the common point where the catheter hangs when entering the anterior circulation. The MCA is initially defined by a single M1 segment and then further branches into two or three M2 segments and then further arborizes to create the M3 segments. These points where the catheter hangs can significantly increase the time required to restore blood perfusion to the brain, which is disadvantageous in the treatment of AIS and has serious consequences.

[0074] As people age, the large blood vessels generally expand and elongate. The internal carotid artery, fixed proximally and distally, usually becomes tortuous with age. The common carotid artery CCA is relatively fixed within the thoracic cavity as it enters the neck region through the clavicle. The external carotid artery ECA and the internal carotid artery ICA are not fixed relative to the common carotid artery CCA, and thus, with age and the elongation of the entire carotid artery system, they become tortuous. This can cause them to elongate and kink and become tortuous, or in the worst-case scenario, form a complete loop or a so-called "neck loop". If the catheter used to traverse these kinked or curved areas is too stiff or not flexible enough, these areas may be subjected to straightening, which can lead to vessel entanglement or a "barbershop pole", resulting in significant kinking and folding of the vessel. These extreme tortuosities also significantly increase the time required to restore blood perfusion to the brain, especially in the aging population. In some cases, if the blood vessel twists on its own or if an untwisted artery kinks, normal antegrade blood flow may be reduced to stasis, causing local ischemia. Manipulating the loosening or unknotting of blood vessels such as the cervical ICA may also increase the time required to perform the procedure.

[0075] The main drawbacks of current catheter systems for stroke intervention procedures are the amount of time required to restore blood perfusion to the brain, including the time required to access one or more occluded sites in the cerebral arteries and the time required to completely clear the occlusion from the artery. Since more than one attempt is usually necessary to completely eliminate the occlusion, reducing the number of attempts and the time required to change devices for additional attempts are important factors in minimizing the total time. Additionally, each attempt is associated with potential procedural risks due to the advancement of the device through the delicate cerebrovascular system. Another limitation is the need for multiple operators to deliver and effectively manipulate a long triaxial system with multiple RHVs that are typically used with a conventional guiding catheter and a distal access catheter.

[0076] This document describes catheter systems and methods for treating various neurovascular pathologies, such as acute ischemic stroke (AIS). The systems described herein provide rapid and simple single-operator access to distal target anatomy, particularly tortuous anatomy of the cerebral vasculature, at a single manipulation point. The medical methods, devices, and systems described herein allow navigation of complex, tortuous anatomy for rapid and safe aspiration and clearance of cerebral occlusions to treat acute ischemic stroke. The medical methods, devices, and systems described herein can also be used to deliver intracranial medical devices, whether aspiration is required to clear a cerebral occlusion during the treatment of acute ischemic stroke or not. Whether the user intends to perform aspiration alone as a first-line treatment for AIS or not, the systems described herein are particularly useful for the treatment of AIS. Additionally, the extremely high flexibility and deliverability of the distal access catheter systems described herein allow the catheter to assume the shape of the tortuous anatomy rather than applying a straightening force to create a new anatomy. The distal access catheter systems described herein can traverse tortuous loops while maintaining the natural curvature of the anatomy therein, thereby reducing the risk of vessel straightening. Thus, the distal access catheter systems described herein can form a safe conduit through the neurovascular system, thereby maintaining the natural tortuosity of the anatomy for other catheters to cross (e.g., a large-bore aspiration catheter).

[0077] The devices, systems, and methods of use described herein are related to, and can be used in combination with and alternatively to, the devices, systems, and methods of use described in U.S. Publication No. 2013 / 0035628, filed Aug. 3, 2012, U.S. Publication No. 2015 / 0173782, filed Dec. 19, 2014, and U.S. Publication No. 2016 / 0220741, filed Feb. 4, 2016. The disclosures of each of these publications are incorporated herein by reference in their entirety.

[0078] Although some embodiments are described herein specifically with respect to accessing neurovascular anatomy for applying aspiration, the systems and methods described herein should not be limited thereto and may also be applicable to other uses. For example, the catheter systems described herein can be used to deliver working devices to target vessels in coronary anatomy or other vascular anatomy. When using the phrases "distal access catheter" or "aspiration catheter" herein, the catheter can be used for aspiration, delivering fluid to a treatment site, or serving as a support catheter, or providing a distal access for facilitating and guiding the delivery or replacement of other devices (such as guidewires) or interventional devices (such as stent retrievers). Alternatively, the access systems described herein can also be used to access other parts of the body outside the vascular system. Similarly, when the working device is described as an expandable brain treatment device, a stent retriever, or a self-expanding stent, other interventional devices can be delivered using the delivery systems described herein.

[0079] Reference is now made to the accompanying drawings, Figures 2A - 2BSystem 100 is shown, which includes devices for accessing and clearing brain occlusions to treat acute ischemic stroke. System 100 can be a single-operator system such that one operator can deliver and use each component and the system together with a single-point operation that requires minimal hand movement. As will be described in more detail below, all wire and catheter manipulations can occur at a single rotary hemostatic valve (RHV) 434 or at more than one RHV co-located in the same device or adjacent to the single rotary hemostatic valve 434 or the more than one RHV. System 100 can include one or more catheter delivery systems 150, each having a catheter 200 and a catheter advancement element 300. The catheter delivery system 150 is configured to advance through an access guide sheath 400. The catheter 200 is configured to be received through the guide sheath 400 and is designed to have excellent deliverability. The catheter 200 can be a stylet-tipped distal access catheter coaxial with the lumen of the guide sheath 400, thereby providing a stepped increase in inner diameter within the catheter. The catheter 200 can be delivered using a catheter advancement element 300 inserted through the lumen 223 of the catheter 200. System 100 can be a distal access system, which can create a variable length from an access point (e.g., femoral artery) of a percutaneous arteriotomy to a target control point of a distal catheter. Conventional distal access systems for stroke intervention typically include a long guide sheath or guiding catheter placed through a shorter "introducer" sheath (e.g., 11 - 30 cm in length) at the groin. The long guide sheath is typically located in the ICA to support neurovascular interventions including stroke thrombectomy (sometimes referred to as "thrombectomy"). To increase support, they can be advanced up to the end of the petrous bone and rarely enter the cavernous or clinoid or supraclinoid segment of the ICA when possible. To reach a target in the M1 or M2 distribution for an ADAPT / MAT or Solumbra / SMAT approach, additional catheters can be inserted through the long guiding catheter. These catheters are typically large-bore aspiration catheters, which can be, for example, 130 cm or longer in length. As will be described in more detail below, when considered as a system measured from the access point (usually the common femoral artery), the distal access system 100 described herein can be shorter, for example, only 115 cm in length. Additionally, a single operator can use the system described herein by inserting the system described herein through a single rotary hemostatic valve (RHV) 434 on the guide sheath 400 or more than one RHV co-located in the same device (e.g., a dual-headed RHV). Thus, a process that was once a two-operator procedure can be a single-operator procedure.

[0080] The individual components of the various systems will now be described in more detail.

[0081] Access guide sheath

[0082] Against Figures 2A - 2D, the distal access system 100 may include an access guide sheath 400 having a body 402. A working lumen extends through the body 402 from a proximal hemostatic valve 434 coupled to a proximal region 403 of the body 402 to a distal opening 408 in a distal region. The working lumen is configured to receive a catheter 200 therethrough such that a distal end of the catheter 200 can extend beyond a distal end of the sheath 400 through the distal opening 408. The guide sheath 400 can be used to deliver the catheters described herein as well as any of a variety of working devices known in the art. For example, the working device can be configured to provide a thrombotic treatment and can include a large-bore catheter, aspiration thrombectomy (or thromboembolectomy), a push catheter, a guide wire, a balloon, a retrievable structure (such as a coil-bearing retrievable stent “stent retriever”). The guide sheath 400 in combination with the catheter 200 can be used to apply distal aspiration, as will be described in more detail below.

[0083] The guide sheath 400 can be any of a variety of commercially available guide sheaths. For example, the guide sheath 400 can have an ID between 0.087”-0.089”, such as the Cook SHUTTLE 6F (Cook Medical, Inc. of Bloomington, Indiana), Terumo DESTINATION 6F (Terumo Europe NV), Cordis VISTA BRITE TIP (Cordis Corporation of Hialeah, Florida), and Penumbra NEURON MAX 088 (Penumbra, Inc. of Alameda, California), Stryker Infinity (Stryker Neurovascular of Fremont, California) or similar commercially available guide sheaths. Generally, the French (F) scale is used herein to describe sheath sizes. For example, when a sheath is described as 6 French, the inner diameter of the sheath is capable of receiving a catheter with an outer diameter of 6F, which outer diameter is approximately 1.98 mm or 0.078”. A catheter can be described herein as having a specific size in French, indicating its compatibility for receiving the outer diameter of another catheter within its inner diameter. A catheter can also be described herein as having a specific size in French, indicating its compatibility for having an outer diameter that is compatible with another catheter having a specific inner diameter.

[0084] The guide sheath 400 can have various sizes to receive various working devices such as the catheter 200 and can accommodate the preferences of the operator. The working lumen of the guide sheath 400 can be sized to receive its corresponding catheter 200 in a sliding fit manner. Generally, it is desirable to minimize the overall size of the vascular insertion site by limiting the outer diameter of the guide sheath 400 to less than 0.122". It is also desirable to select the corresponding outer and inner diameters to provide a good sliding fit between the catheter 200 and the guide sheath 400. The inner diameter of the working lumen of the guide sheath can be at least 0.001" larger than the maximum outer diameter of any catheter 200 it is intended to receive, especially when the catheter 200 will be used for aspiration. The inner diameter of the working lumen can be sized to accommodate at least a 6 French catheter (1.98 mm or 0.078"), or at least a 6.3 French catheter (2.079 mm or 0.082" OD), or at least a 7 French (2.31 mm or 0.091" OD) catheter, or an 8 French (2.64 mm or 0.104" OD) or larger catheter. However, the inner diameter of the guide sheath 400 can be smaller or larger to be compatible with other catheter sizes. Regardless of the length and inner diameter, the guide sheath 400 does not kink during advancement distally through the blood vessel.

[0085] The aspiration catheter described herein may have an ID between 0.054” and 0.088”. If the catheter 200 has an inner diameter of 0.088” and has a maximum outer diameter between 0.105” and 0.107”. The guide sheath 400 may in turn have a working lumen with an inner diameter between 0.106” and 0.108”. Generally, the difference or gap between the maximum outer diameter of the catheter 200 and the inner diameter of the guide sheath 400 is less than about 0.002”, for example between 0.001” and 0.002”. The low-gap region between the maximum outer diameter of the catheter 200 and the inner diameter of the guide sheath 400 may be restricted to a local area. This means that the low-gap fit between the two may only extend over a small portion of the cylindrical length of the catheter 200 and the sheath 400. Thus, the OD-ID difference between the catheter 200 and the guide sheath 400 may be greater than or equal to 0.002” along a first cylindrical length where the two devices overlap during use, and less than 0.002” along a different cylindrical length of the overlap, thereby providing a local area of low gap within the overlap. This allows for convenient relative slidability and sufficient sealing when placed under aspiration pressure, as will be described in more detail below. For example, the distal region of the guide sheath 400 may have a first inner diameter at the distal end region and a different second inner diameter at the proximal end region such that the low gap of the sliding fit with the catheter 200 varies along its length. In some embodiments, the catheter 200 has a first outer diameter at the distal end region and a second larger outer diameter at the proximal end region. The larger second outer diameter may be less than 0.002” of the inner diameter of the sheath 400, while the first outer diameter may be greater than 0.002” of the inner diameter of the sheath 400. This provides a tighter overall fit between the guide sheath 400 and the proximal end region of the catheter 200 at the location of this larger second outer diameter.

[0086] Again with respect to Figures 2A - 2D, the sheath body 402 can extend from a proximal branch or a rotary hemostatic valve (RHV) 434 at the proximal region 403 to a tip 406 at the distal end of the body 402. The proximal RHV 434 can include one or more lumens molded into the connector body to connect to the working lumen of the body 402 of the guide sheath 400. The working lumen can receive the catheter 200 and / or any of a variety of working devices for delivery to a target anatomical structure. The RHV 434 can be composed of a thick-walled polymer tube or a reinforced polymer tube. The RHV 434 allows devices to be introduced into the vasculature through the guide sheath 400 while preventing or minimizing blood loss and preventing air from being introduced into the guide sheath 400. The RHV 434 can be integrated with the guide sheath 400, or the guide sheath 400 can terminate at the proximal end of a female Luer adapter to which a separate hemostatic valve component, such as a passive seal valve, a Tuohy-Borst valve, or a rotary hemostatic valve, can be attached. The RHV 434 can have an adjustable opening that is large enough to allow removal of a device with a clot adhered to the tip without causing the clot to dislodge at the RHV 434 during removal. Alternatively, the RHV 434 can be removable, for example, when removing a device from the sheath 400 to prevent a clot from shifting at the RHV 434. The RHV 434 can be a dual RHV.

[0087] The RHV 434 can form a Y-shaped connector on the proximal end 403 of the sheath 400 such that a first port of the RHV 434 can be used to insert a working catheter into the working lumen of the sheath 400, while a second port in the access arm 412 can be used for another purpose. For example, a syringe or other device can be connected at the arm 412 via the connector 432 to deliver a forward drip, a flush line for contrast agent or saline injection, and into the target anatomical structure through the body 402 toward the tip 406. The arm 412 can also be connected to a suction source 505 (see Figure 2B)。The aspiration source 505 can be an active aspiration source configured to draw aspiration through the working lumen, such as an aspiration pump, a regular or locking syringe, a hand-held aspirator, a hospital aspirator, etc. In one embodiment, the aspiration source 505 is a locking syringe (such as a VacLok syringe) attached to a flow controller. Before the embolus removal step of the operation, while closing the connection to the pipeline, the user can pull the plunger on the syringe back to the locked position. During operation, when the tip of the catheter is near or at the occluded surface, the user can open the connection to the aspiration syringe. This allows for maximum transfer of the suction force applied through the working lumen of the sheath 400 and any catheter extending through the sheath 400, which in turn communicates with the blood vessel at its distal end. Aspiration can be quickly applied by a single user at a single shared source. In another embodiment, the arm 412 can be connected to the aspiration source 505, which is a pump configured to apply aspiration pressure through the working lumen of the guiding sheath 400. Even when multiple aspiration catheters 200 are nested within each other through the working lumen of the guiding sheath 400, a single shared aspiration source is sufficient to draw aspiration through the entire system 100. The arm 412 also allows for flushing the guiding sheath 400 with saline or radiopaque contrast agent during the operation. The working lumen can extend from the distal end of the sheath body 402 to the working proximal port in the proximal region 403.

[0088] The length of the catheter body 402 is configured to allow the distal tip 406 of the body 402 to be positioned distally from, for example, the internal carotid artery (ICA) for a transfemoral approach, where the additional length provides for adjustment if necessary. In some embodiments (e.g., femoral or radial percutaneous access), the length of the body 402 can be in the range of 80 to 90 cm or can be longer, e.g., up to about 100 cm or up to about 105 cm. In an embodiment, the length of the body 402 is suitable for a transcarotid approach to a branch of the carotid artery and is in the range of 20 - 25 cm. In additional embodiments, the length of the body 402 is suitable for a percutaneous transcarotid approach to the CCA or proximal ICA and is in the range of 10 - 15 cm. The body 402 is configured to withstand and navigate the bends of the vasculature without kinking, collapsing, or causing vascular trauma even when, for example, subjected to high suction forces.

[0089] In some embodiments, system 100 may further include a selection tool for advancing guide sheath 400. The selection tool may have an outer diameter configured to receive within the working lumen of guide sheath 400 such that the distal region of the selection tool extends a distance distally beyond the distal end of guide sheath 400. The outer diameter of the selection tool sufficiently fills the inner diameter of the working lumen of guide sheath 400 to minimize the lip at the distal opening 408 of guide sheath 400. For example, if the inner diameter of the working lumen of guide sheath 400 is between about 0.087” and about 0.113”, the outer diameter of the selection tool may be about 0.006” less than the inner diameter, or between about 0.081” and about 0.107”. The brachiocephalic trunk (BT) is typically a very steep branch of the aortic arch AA for a catheter for transfemoral delivery seeking right cerebral circulation ( Figure 1C shown). The catheter passes from the femoral artery through the iliac circulation and into the descending aorta DA. The catheter rotates as it approaches the aortic arch AA and passes through the origins of the other major vessels to reach the brachiocephalic trunk (BT), which is the most distal “reach” of the major vessels of the aortic arch AA. Figure 1C An obvious mandatory S-shaped turn is shown resulting from this anatomy. The catheter must traverse this S-shaped turn along the insertion path from the femoral artery insertion site to reach the internal carotid artery (ICA). The left ICA typically originates from the brachiocephalic trunk and thus faces a similar challenge and may result in a sharper S-shaped turn. If the left ICA has a typical origin between the brachiocephalic BT and the origin of the left subclavian artery LSA, the situation may be less severe, but the S-shaped turn will still occur less acutely. The distal region of the selection tool may be tapered and / or shaped to provide support and guidance for sheath 40 around this turn as it advances into the ICA. In some embodiments, the selection tool may have a Bernstein Select-type or Simmons-type reverse curve catheter tip known in the art.

[0090] The tip 406 of guide sheath 400 may have an outer diameter that is the same as or similar to the distal portion of the body 402 leading to the distal end. Thus, the tip 406 may have a distal face orthogonal to the longitudinal axis passing through the body 402, and the distal face may have an outer diameter that is substantially equal to the outer cross-sectional dimension of the body 402. In one embodiment, the tip 406 includes a chamfer, rounded corner, or tapered portion such that the distal face diameter is slightly less than the cross-sectional dimension of the body 402. In additional embodiments, the tip 406 may be an elongate tubular portion that extends distally into a region of the body 402 having a uniform outer diameter such that the elongate tubular portion has a reduced diameter compared to the uniform outer diameter of the body 402. Thus, the tip 406 may be elongate or may be more bluntly shaped. Accordingly, the tip 406 may be configured to smoothly track through the vasculature and / or dilate vascular restrictions as it tracks through the vasculature. The working lumen may have a distal end that forms the distal opening 408.

[0091] The guiding sheath 400 may include a tip 406 that tapers from a portion of the body 402 leading to the distal end. That is, the outer surface of the body 402 may have a diameter that decreases from a larger size to a smaller size at the distal end. For example, the tip 406 may taper from an outer diameter of approximately 0.114" to about 0.035", or from an outer diameter of about 0.110" to about 0.035", or from an outer diameter of about 0.106" to about 0.035". The taper angle of the tip 406 may vary depending on the length of the tapered tip 406. For example, in some embodiments, the tip 406 tapers from 0.110" to 0.035" over a length of approximately 50 mm.

[0092] In one embodiment, the guiding sheath 400 includes one or more radiopaque markers 411. The radiopaque markers 411 may be disposed near the distal tip 406. For example, a pair of radiopaque bands may be forged, painted, embedded, or otherwise disposed in or on the body 402. In some embodiments, the radiopaque markers 411 include barium polymers, tungsten polymer blends, tungsten-filled or platinum-filled markers that maintain the flexibility of the distal end of the device and improve the transition along the length of the guiding sheath 400 and its kink resistance. In some embodiments, the radiopaque markers 411 are tungsten-loaded PEBAX or polyurethane that are heat-welded to the body 402. The markers 411 are shown in the figures as rings around the circumference of one or more regions of the body 402. However, the markers 411 may have other shapes or create various patterns to provide the operator with an orientation regarding the position of the distal opening 408 within the blood vessel. Thus, the operator may visualize the position of the distal opening 408 under fluoroscopy to confirm that the distal opening 408 is directed at the target anatomical structure where the catheter 200 is to be delivered. For example, the radiopaque markers 411 allow the operator to rotate the body 402 of the guiding sheath 400 at the anatomical entry point (e.g., the patient's groin) such that the distal opening provides access to the ICA via subsequent working devices (e.g., a catheter and a guide wire advanced into the ICA). In some embodiments, the radiopaque markers 411 include platinum, gold, tantalum, tungsten, or any other material visible under x-ray fluoroscopy. Any of the various components of the systems described herein may incorporate radiopaque markers.

[0093] In some embodiments, the guide sheath 400 may have performance characteristics similar to other sheaths used in carotid access and AIS procedures in terms of kinkability, radiopacity, column strength, and flexibility. The inner lining may be composed of a low-friction polymer (such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene)) to provide a lubricious surface for advancing the device through the inner lumen. The outer sleeve material may provide mechanical integrity to the inner lining and may be composed of materials such as PEBAX, thermoplastic polyurethane, polyethylene, nylon, etc. The body 402 may include a hydrophilic coating. A third layer may be incorporated, which may provide reinforcement between the inner lining and the outer sleeve. The reinforcement layer may prevent the inner lumen of the body 402 from flattening or kinking to allow the device to pass unobstructed through bends in the vasculature and for aspiration or reflux navigation. The body 402 may be circumferentially reinforced. The reinforcement layer may be made of a metal such as stainless steel, nitinol, nitinol braid, helical band, helix, cut stainless steel, or a rigid polymer such as PEEK. The reinforcement layer may be a structure such as a coil or braid, or a tube that has been laser cut or machine cut to be flexible. In another embodiment, the reinforcement layer may be a cut hypotube (such as a nitinol hypotube) or a cut rigid polymer, etc. The outer sleeve of the body 402 may be formed of a material with a gradually increasing softness towards the distal end. The flexibility of the body 402 may vary along its length, with the flexibility increasing towards the distal portion of the body 402. The variability of flexibility may be achieved in various ways. For example, the hardness and / or material of the outer sleeve may vary in different sections. A lower hardness outer sleeve material may be used in the distal portion of the guide sheath compared to other parts of the guide sheath. Alternatively, the wall thickness of the sleeve material may be reduced, and / or the density of the reinforcement layer may be altered to increase flexibility. For example, the pitch of the coil or braid may be stretched, or the cut pattern in the tube may be varied to be more flexible. Alternatively, the reinforcement structure or material may vary along the length of the sheath body 402. In another embodiment, there is a transition portion between the most distal flexible portion and the proximal portion, where there are one or more portions with different flexibilities between the most distal portion of the sheath body 402 and the rest of the portion. In this embodiment, the most distal portion is about 2 cm to about 5 cm, the transition portion is about 2 cm to about 10 cm, and the proximal portion occupies the remainder of the sheath length. In some embodiments, the proximal region of the body 402 may be formed of a material such as nylon, the region of the body 402 located distal to the proximal region of the body 402 may have a material hardness of 72D, and the flexibility of the more distal regions may gradually increase and be formed of materials having material hardnesses of 55D, 45D, 35D extending towards the distal tip 406. For example, it may be formed of a material having a material hardness of 35D.

[0094] The working lumen of the guiding sheath 400 may have different inner diameters configured to receive catheters 200 of different outer diameters. In some embodiments, the working lumen of the first guiding sheath 400 may have an inner diameter sized to receive a 6F catheter, and the working lumen of the second guiding sheath 400 may have an inner diameter sized to receive an 8F catheter. The guiding sheath 400 may receive a catheter that has an outer diameter along at least a length that conforms to the inner diameter size of the guiding sheath 400. The guiding sheath 400 (and any of the various components used in conjunction with the sheath) may be an over-the-wire (OTW) or rapid exchange device, which will be described in more detail below.

[0095] The sheath 400 may include a body 402 that is typically formed of three layers, including a lubricious inner liner, a reinforcement layer, and an outer sleeve layer. The reinforcement layer may include a braid to provide good torsionality and may optionally be covered with a coil to provide good kink resistance. In sheaths where the reinforcement layer is only a braid, the polymer of the outer sleeve layer may typically be harder and thicker to avoid kinking issues. The wall thickness of such a sheath braided only with a thicker polymer may be about 0.011". The wall thickness of the sheath 400 having a braid covered with a coil as described herein provides torsionality and kink resistance and may have a generally thinner wall, e.g., a wall thickness of about 0.0085". Thus, the proximal outer diameter may be reduced to less than 0.112", e.g., an outer diameter of about 0.107". It is generally beneficial to limit the overall OD of the guiding sheath 400 such that the entry into the patient's body (e.g., at the femoral artery) can be kept to a minimum size. Thus, the sheath 400 is a high-performance sheath 400 having good torsionality and kink resistance, where the thinner wall provides an overall lower profile for the system. The thinner wall and lower profile allow for a smaller insertion hole through the blood vessel without affecting the overall lumen size. In some embodiments, the wall thickness of the guiding sheath 400 may decrease slowly in a stepped manner towards the distal end of the sheath as compared to the proximal end.

[0096] The system can include a low-clearance local point between the guide sheath 400 and the catheter 200 extending through the guide sheath 400. The low-clearance local point can provide a local seal between the structures. In some embodiments, the local seal can be near the distal region of the guide sheath 400, while in other embodiments, the local seal can be a distance away from the distal end of the guide sheath 400. The OD of the catheter 200 can increase near the proximal region of the cylindrical region forming the catheter, so as to form a tight fit with the ID of the guide sheath 400 (e.g., a clearance less than about 0.002”). The length of the low-clearance seal region can vary and depends on the total clearance between the ID and OD. By increasing the length of the cylindrical seal region, a larger difference in ID / OD (i.e., a higher clearance) can provide sufficient sealing under suction pressure. A smaller difference in ID / OD (i.e., a smaller clearance) can provide sufficient sealing under suction pressure while having a shorter cylindrical length. In other words, a shorter seal region can have a tighter fit or a lower clearance, while a longer seal region does not need to have such a tight fit and can have a higher clearance.

[0097] The guide sheath 400 can also include additional local seal points through which the catheter extends through its working lumen. In some embodiments, the local seal can occur at a distance from the distal end 406 of the sheath 400. In some embodiments, the local seal can occur at the distal end 406 of the sheath 400. For example, the guide sheath 400 can include a distal tip 406 that is designed to seal well with the outer diameter of the catheter extending through its working lumen. The distal tip 406 can be formed of a soft material without both a lining layer and a reinforcing layer. In addition to the length of the distal tip 406, the lubricious lining layer and the reinforcing layer can extend through most of the body 402 (see Figure 2C)。The length of this unlined and un-reinforced portion of the distal tip 406 of the sheath 400 can vary. In some embodiments, the length is between about 3 mm and about 6 mm in the distal region of the sheath 400. Thus, the liner 409 of the sheath 400 can terminate at least about 3 mm from the farthest distal end of the sheath 400, leaving a final 3 mm of unlined soft material to form the distal tip 406. In some embodiments, the ends of the coils and braids of the reinforcement layer can be held in place by radiopaque markers 411, such as marker bands positioned near the farthest distal end of the sheath 400. The liner layer 409 can extend at least to a length distal to the marker band 411 before termination, for example, a length of about 1 mm. The staggered termination of the wall layers can facilitate the transition of the soft polymeric material 407 from the marker band 411 to the distal tip 406. The soft polymeric material 407 can extend beyond the length of the liner layer 409. The unlined soft material 407 forming the distal tip 406 can be a PEBAX material having a hardness of no greater than about 40D, no greater than about 35D, no greater than about 62A, or no greater than about 25D. The softness and length of the material of this unlined distal tip 406 of the sheath 400 can vary. Generally, the material is soft enough to be compressed, for example, onto the outer diameter of the catheter 200 extending through the lumen of the sheath 400 when negative pressure is applied through the lumen. The length of the unlined and un-reinforced region 407 of the distal tip 406 is long enough to provide a good seal but not so long as to cause problems such as accordion folding or doubling over during relative sliding between the sheath 400 and the catheter 200, which could block the sheath lumen or have a negative impact on the slidability of the catheter 200 within the sheath lumen.

[0098] The inner diameter of the distal tip 406 can be close to the outer diameter of the catheter 200 extending through the sheath 400. In some embodiments, the inner diameter of the distal tip 406 can vary according to the size of the catheter to be used. For example, when the outer diameter of the catheter near the proximal end is about 0.101", the inner diameter of the sheath at the distal tip 406 can be about 0.106", such that the difference in diameter is about 0.005". After application of a vacuum, the soft unlined and un-reinforced distal tip 406 can move to eliminate this 0.005" gap and compress onto the outer diameter near the proximal region of the catheter 200 as the catheter 200 extends out of its distal opening 408. The difference between the inner diameter of the distal tip 406 and the outer diameter of the catheter can be between about 0.002" and 0.006". The inner diameter of the distal tip 406 can also be tapered such that the inner diameter at the farthest distal end of the opening 408 is only 0.001" to 0.002" larger than the outer diameter of the proximal end of the catheter 200 extending through the working lumen. In some embodiments, the distal tip 406 is shaped such that the wall is at an angle relative to the central axis of the sheath 400, for example, about 60 degrees.

[0099] In some cases, it is desirable for the sheath body 402 to also be able to occlude the artery in which it is positioned, for example, during an operation where distal embolization may occur. Occluding the artery prevents antegrade blood flow, thereby reducing the risk of distal embolization that may cause neurological symptoms such as TIA or stroke. Figure 2D An arterial access device or sheath 400 with a distal occlusion balloon 440 is shown. The distal occlusion balloon 440, when inflated, occludes the artery at the location of the distal tip 406 of the sheath. At any point during the operation, for example, during aspiration to clear the occlusion and / or delivery of a stent retriever or other interventional device, the occlusion balloon 440 can be inflated to occlude the blood vessel, thereby reducing the risk of distal embolization to the cerebral blood vessels. In addition to the working lumen of the sheath 400, the sheath 400 can include an inflation lumen that is configured to deliver fluid for inflation of the occlusion balloon 440. The inflation lumen can fluidly connect the balloon 440 to an arm 412 on a proximal adapter, for example. The arm 412 can be attached to an inflation device such as a syringe to inflate the balloon 440 with fluid when vascular occlusion is desired. The arm 412 can be connected to a passive or active aspiration source to further reduce the risk of distal embolization.

[0100] According to some embodiments, the length of the guiding sheath 400 is long enough to access the target anatomy and exit the arterial access site with additional length outside the patient's body for adjustment. For example, the guiding sheath 400 (with or without a distal occlusion balloon 440) can be long enough to enter the Petrolet ICA from the femoral artery, leaving additional length available for adjustment.

[0101] The sealing gap between the guiding sheath 400 and the catheter 200 can be a function of a locally low-gap region in the ID / OD. The size of the gap can vary depending on whether aspiration pressure is applied through the system. For example, the catheter 200 can also include a lumen portion 222 ( Figure 5BThe slit 236 (shown in []) is configured to slightly widen when suction is applied from a suction source and improve the seal between the catheter 200 and the guiding sheath 400. Additionally or alternatively, the distal tip 406 of the sheath 400 can be designed to move downward onto the outer diameter of the catheter 200 to improve the seal. The strength of the achieved local seal allows for a continuous suction lumen from the distal tip of the catheter 200 to the proximal end 403 of the guiding sheath 400, where the proximal end 403 of the guiding sheath 400 is connected to the suction source even in the presence of a relatively low suction force. There is little leakage. Generally, when there is sufficient overlap between the catheter 200 and the guiding sheath 400, there is substantially no leakage. However, when attempting to reach a distal anatomical structure, the catheter 200 can be advanced to its limit, and the overlap between the catheter 200 and the guiding sheath 400 is minimal. Therefore, additional sealing may be desired to prevent leakage around the catheter 200 into the sheath 400. The seal between the catheter 200 and the guiding sheath 400 can prevent such leakage when the catheter 200 is maximally extended relative to the sheath 400.

[0102] Distal access catheter

[0103] Against Figures 2A - 2B For [], the distal access system 100 can include one or more catheters 200 configured to extend through the distal end of the guiding sheath 400 and extend out from the distal end of the guiding sheath 400. Depending on the method being performed, the catheter 200 can be a distal access, support, or suction catheter. Figure 3 A side view of an embodiment of the catheter 200 is shown. The catheter 200 includes a relatively flexible distal lumen portion 222 that is coupled to a more rigid, kink-resistant proximal extension or proximal control element 230. The term "control element" as used herein can refer to a proximal region configured to cause a pushing movement in the distal direction and a pulling movement in the proximal direction by the user. The control elements described herein can also be referred to as stylets, tethers, wires, push tubes, or other elements having any of a variety of configurations. The proximal control element can be a hollow or tubular element. The proximal control element can also be solid and not have an internal lumen, such as a solid rod, strip, or other solid linear element. Generally, the proximal control elements described herein are configured to move their respective components (which can be attached or integrated therewith) bidirectionally through the lumen.

[0104] The catheter 200 provides a method for simply and quickly accessing a stroke location even through the extreme tortuosity of the cerebral blood vessels. The catheters described herein have a degree of flexibility and deliverability such that they are optimally suited for advancing through the cerebral vascular anatomy without kinking or forming an oval even when navigating sharp turns. For example, the distal lumen portion 222 can perform a 180-degree turn (see Figure 1BThe T-shaped turn near the carotid siphon shown) and maintains a folded width of 4.0 mm without kinking or forming an oval. In addition, the distal lumen portion 222 has a degree of flexibility to maintain the natural tortuous advancement of the blood vessel through which it passes without applying a straightening force, so that the natural shape and curvature of the anatomical structure are maintained during use. The catheter 200, particularly in combination with the catheter advancement element 300 (to be described in more detail below), provides a tubing that extends beyond the guide sheath 400 and has excellent deliverability through the curved anatomical structure, thereby allowing suction to be delivered to the target stroke site and allowing the delivery of a stroke intervention device (such as another suction catheter) or a device such as a stent retriever, stent, shunt, or other working device.

[0105] A single internal lumen 223 extends through the lumen portion 222 between the proximal and distal ends of the lumen portion 222. The internal lumen 223 of the catheter 200 may have a first inner diameter, and the working lumen of the guide sheath 400 may have a larger second inner diameter. When the catheter 200 is inserted through the working lumen of the sheath 400, the lumen 223 of the catheter 200 may be configured to be in fluid connection and abut with the working lumen of the sheath 400, such that fluid can flow into and / or out of the system 100, for example, by applying suction from a suction source connected to the system 100 at the proximal end. The combination of the sheath 400 and the catheter 200 may be in continuous communication with the blood flow during proximal suction as the catheter 200 is advanced and retracted.

[0106] Compared to conventional full-length catheters, the stylet catheter system provides benefits for distal access, particularly in terms of suction. The stepped change in catheter inner diameter (i.e., from the lumen 223 of the catheter to the working lumen of the sheath 400) provides significant benefits in terms of the suction flow and forces that can be generated by the combination of the stylet catheter 200 and a conventional guiding catheter. For example, a stylet catheter 200 with an inner diameter of 0.070” paired with a standard 6F outer diameter / inner diameter of 0.088” guiding catheter (such as the Penumbra NeuronMAX 088) will produce a suction physics phenomenon where the 0.088” catheter diameter will dominate and produce an equivalent flow rate of 0.080 throughout the system.

[0107] In addition to suction operations, the catheter 200 and the distal access system 100 can be used for the delivery of tools and interventional working devices. For example, a typical stent retriever to be delivered through the catheter 200 may have a long wire pusher control element (such as 180 cm long). The distal access system 100 with the stylet support catheter 200 allows access to the distal stroke site using a much shorter length (such as 120 cm - 150 cm). When aspirating through the catheter, the total length can be as important as the diameter and radius. The shorter length combined with the elimination of the typical multiple RHVs in a triaxial system allows a single operator to use it.

[0108] When the catheter is described herein as a suction catheter, it should not be limited to suction only. Similarly, when the catheter is described herein as a means for delivering a stent retriever or other working device, it should not be limited in that way. The systems described herein can be used to perform procedures that include a combination of therapies. For example, optionally in the presence of suction through catheter 200, catheter 200 can be used to deliver a stent retriever delivery system. As another example, a user can start performing a first interventional procedure, such as suction thrombectomy (sometimes referred to as "thrombectomy"), using the systems described herein and switch to another interventional procedure, such as delivering a stent retriever or an implant.

[0109] The terms "support catheter", "spike catheter", "tethered catheter", "distal access catheter", "suction catheter", and "intermediate catheter" may be used interchangeably herein.

[0110] It is desirable to have a catheter 200 with as large an inner diameter as possible that is capable of safely navigating to an occluded site in order to optimize suction force in the case of suction and / or provide sufficient clearance for delivering a working device. Depending on the patient's anatomy and the size and composition of the blood clot, a suitable size for the inner diameter of the distal lumen portion 222 can range between 0.040" and 0.100", or more preferably between 0.054" and 0.088". The outer diameter of the distal lumen portion 222 can be sized to navigate into a cerebral artery, for example, at the level of the M1 or M2 segment of the cerebral vasculature. The outer diameter (OD) should be as small as possible while still maintaining the mechanical integrity of the catheter 200. In one embodiment, the difference between the OD of the distal lumen portion 222 of the catheter 200 and the inner diameter of the working lumen of the guiding sheath 400 is between 0.001" and 0.002". In another embodiment, the difference is between 0.001" and 0.004". The clearance between the inner diameter of the guiding sheath 400 and the outer diameter of the catheter 200 can vary along the entire length of the catheter 200. For example, the distal lumen portion 222 of the catheter 200 can have a local region of enlarged outer diameter, creating a local low-clearance region (e.g., a difference of about 0.001"), which is configured to provide a local seal when suction pressure is applied through the system.

[0111] In some embodiments, the distal lumen portion 222 of the catheter 200 has a maximum outer diameter (OD) that is configured to fit through a 6F introducer sheath (0.070” - 0.071”), and the inner diameter (ID) of the lumen 223 is sized to receive a 0.054” catheter. In some embodiments, the distal lumen portion 222 has a lumen and a distal end with an opening from the lumen, and the lumen may have an inner diameter (ID) of at least about 0.052” at the distal end. In some embodiments, the distal lumen portion 222 of the catheter 200 has a maximum OD that is configured to fit through an 8F introducer sheath (0.088”), and the ID of the lumen 223 is sized to receive a 0.070” or 0.071” catheter. In some embodiments, the maximum OD of the distal lumen portion 222 is 2.1 mm, and the ID of the lumen 223 is 0.071”. In some embodiments, the lumen 223 has an ID between 0.070” and 0.073”. The outer diameter of the guiding sheath 400 may be adapted to be inserted at least into the carotid artery, wherein the working lumen is appropriately sized to provide a passage for the catheter 200 to treat an occlusion distal to the carotid artery towards the brain. In some embodiments, the ID of the working lumen may be about 0.074”, and the OD of the body of the guiding sheath 400 may be about 0.090”, corresponding to a 5 French sheath size. In some embodiments, the ID of the working lumen may be about 0.087”, and the OD of the body of the guiding sheath 400 may be about 0.104”, corresponding to a 6 French sheath size. In some embodiments, the ID of the working lumen may be about 0.100”, and the OD of the body of the guiding sheath 400 may be about 0.117”, corresponding to a 7 French sheath size. In some embodiments, the ID of the guiding sheath 400 is between 0.087” and 0.088”, and the OD of the distal lumen portion 222 of the catheter 200 is between approximately 0.082” and 0.086”, such that the diameter difference is between 0.001” and 0.005”. Consider smaller or larger sheath sizes. For example, in some embodiments, the ID of the lumen 223 is about 0.088”, and the OD of the distal lumen portion is between 0.101” and 0.102”. However, the ID of a conventional 7 French sheath is only about 0.100”, while the ID of a conventional 8 French sheath is about 0.113”, such that a proper sealing fit (i.e., a 0.011” gap) cannot be provided with the OD of the distal lumen portion of the catheter for aspiration thrombectomy. Thus, the guiding sheath 400 may be designed to have an inner diameter more suitable for a 0.088” catheter, i.e., between 0.106” and 0.107”.In addition, the OD of the 0.088” catheter may stepwise increase from 0.101”-0.102” to about 0.105”-0.107” near the proximal region, thereby providing an optimized local area for sealing with the guide sheath during application of high pressure.

[0112] In one embodiment, the lumen portion 222 of the catheter 200 has a uniform diameter from the proximal end to the distal end. In other embodiments, the lumen portion 222 of the catheter 200 tapers and / or has a stepped decrease towards the distal end of the distal lumen portion 222 such that the outermost distal end of the catheter 200 has a smaller outer diameter compared to the more proximal regions of the catheter 200, e.g., near the location where the distal lumen portion 222 seals with the guide sheath 400. In another embodiment, the OD of the lumen portion 222 of the catheter steps up at or near the overlap portion to more closely match the inner diameter of the sheath, as will be described in more detail below. This stepped increase in the outer diameter may be caused by changing the wall thickness of the catheter 200. For example, the catheter 200 may have a slightly thicker wall near the proximal end compared to the wall thickness of the catheter 200 near the distal end to provide a better seal with the sheath. The catheter 200 may have a thicker wall at this location while maintaining a uniform inner diameter. This embodiment is particularly useful in systems having more than one catheter adapted for a single access sheath size. In some embodiments, the thicker wall may be created by embedding a radiopaque material (e.g., tungsten) such that the local stepped increase in the OD during operation may be visualized. The outer diameter of the catheter 200 may stepwise increase near the proximal region, which is not caused by a thicker wall. For example, the inner diameter of the lumen may also stepwise increase such that the wall thickness remains uniform, but the lumen size increases, thereby increasing the total OD at this location.

[0113] The length of the lumen portion 222 may be shorter than the length of the working lumen of the guide sheath 400 such that when the lumen portion 222 is advanced towards the target location, an overlap region 348 is created between the lumen portion 222 and the working lumen (see Figure 2B)。The length of the overlapping region 348 can vary according to the length of the distal lumen portion 222 and the distance from the distal end of the guiding sheath 400 to the target location. Considering the variations in the occluded site and the site where the distal tip 406 of the guiding sheath 400 can be positioned, the length of the lumen portion 222 can be in the range of about 10 cm to about 80 cm, or in the range between 35 cm and about 75 cm, or in the range between about 45 cm and about 60 cm. In some embodiments, the distal lumen portion 222 of the catheter 200 can be between 45 cm and 70 cm, and the control element 230 of the catheter 200 can be between about 90 cm and about 100 cm. In some embodiments, the catheter 200 can have a total working length of approximately 115 cm. In other embodiments, the working length of the catheter 200 between the proximal end and the distal end of the catheter can be greater than 115 cm, up to about 130 cm. In some embodiments, the catheter 200 can have a working length greater than 130 cm, such as 133 cm, between the proximal tab 234 (or proximal hub) and the distal tip. The distal lumen portion 222 can have an axial length of about 40 cm ± 3 cm. The distal lumen portion 222 can have an axial length of at least about 45 cm up to a length less than the working length of the sheath 400. The body 402 of the guiding sheath 400 can be between about 80 cm and about 90 cm.

[0114] The length of the lumen portion 222 can be less than the length of the body 402 of the guiding sheath 400 such that when the catheter 200 extends from the working lumen, the overlapping region 348 of the inner diameters of the catheter 200 and the working lumen still exists. A seal can be formed within the region of the overlapping region 348. In some embodiments, the length of the lumen portion 222 is sufficient to reach from the region of the internal carotid artery to the region of the M1 segment of the middle cerebral artery (MCA) and other major blood vessels while the proximal region of the lumen portion 222 of the catheter 200 remains proximal to certain tortuous anatomical structures (e.g., within the brachiocephalic origin BT, aortic arch AA, or descending aorta DA). In one embodiment, the lumen portion 222 of the catheter has a length sufficient to position its distal end within the M1 segment of the MCA and its proximal end proximal to the origin leading from the aortic arch. In one embodiment, the lumen portion 222 of the catheter has a length sufficient to position its distal end within the M1 segment of the MCA and its proximal end proximal to the descending aorta DA proximal to the aortic arch AA. In embodiments where the catheter 200 reaches the ICA and the distance to the embolus can be less than 20 cm, it is used in combination with a guiding sheath 400 having a sheath body 402 and a working lumen.

[0115] The distal lumen portion 222 has a length of less than 80 cm, for example, about 45 cm to about 70 cm. The distal lumen portion 222 may permit an overlap region 348 that overlaps with the body 402, within which a seal is formed with the sheath while still providing sufficient access to the intracranial blood vessels. The carotid siphon CS is the S-shaped portion at the end of the ICA, starting from the posterior bend of the cavernous ICA and ending at the ICA branches that enter the anterior cerebral artery ACA and the middle cerebral artery MCA. In some embodiments, the length of the distal lumen portion 222 may be between about 35 cm and 80 cm, or between 40 cm and 75 cm, or between 45 cm and 60 cm, to permit the distal end of the catheter 200 to extend to at least the middle cerebral artery while the proximal control element 230 and / or the sealing element on the proximal region of the distal lumen portion 222 remains proximal to the carotid siphon and preferably within the aorta, as will be described in more detail below.

[0116] The distal lumen portion 222 may have a length measured from the point at which it is attached to the proximal control element 230 to its distal end that is long enough to extend from a region of the internal carotid artery (ICA) proximal to the carotid siphon to a region of the ICA distal to the carotid siphon, including at least the M1 region of the brain. When the lumen portion 222 extends into the target anatomy, there is an overlap region 348 between the lumen portion 222 of the catheter 200 and the working lumen of the guide sheath 400. A seal for the injected or aspirated fluid may be achieved within the overlap region 348, within which the OD of the catheter 200 along at least a portion of the distal lumen portion 222 substantially matches the inner diameter of the guide sheath 400, or the difference may be between 0.001” and 0.002”. The difference between the catheter OD and the inner diameter of the guide sheath 400 may vary, for example, between 1 - 2 thousandths of an inch, or between 1 - 4 thousandths of an inch, or between 1 - 12000 thousandths of an inch. This difference in OD / ID between the sheath and the catheter may be along the entire length of the distal lumen portion 222, or may be the difference in a discontinuous region of the distal lumen portion 222 (e.g., the cylindrical proximal region of the distal lumen portion 222). In some embodiments, a seal for the injected or aspirated fluid between the catheter and the sheath may be achieved between their substantially similar dimensions within the overlap portion 348 without incorporating any separate sealing structure or sealing feature. In some embodiments, an additional sealing structure positioned near the proximal region of the distal lumen portion 222 provides a seal between the inner diameter of the sheath and the outer diameter of the catheter.

[0117] The length of the overlapping region 348 between the sheath and the distal lumen portion varies according to the distance between the distal end of the sheath and the embolus and the length of the lumen portion 222 between its proximal and distal ends. The overlapping region 348 can be sized and configured to form a seal that permits a continuous suction lumen from the distal tip region of the catheter 200 to the proximal region 403 of the guide sheath 400, in which it can be connected to a suction source. In some embodiments, the strength of the seal achieved can be a function of the difference between the outer diameter of the catheter 200 and the inner diameter of the working lumen, the length of the overlapping region 348, the applied suction force, and the materials of the components. For example, the seal can be improved by increasing the length of the overlapping region 348. However, increasing the length of the overlapping region 348 can result in a greater length, whereby suction is pulled through the smaller diameter of the lumen portion 222 rather than the larger diameter of the working lumen. As another example, even in the presence of a shorter overlapping region 348, a higher suction force applied by the suction source can form a stronger seal between the lumen portion 222 and the working lumen. Additionally, a relatively softer material forming the lumen portion and / or the body 402 can provide an adequate seal even with a small suction force and a short overlapping region 348. In one embodiment, the gap in the overlapping region 348 can achieve a seal at a vacuum of up to approximately 28 inHg (inches of mercury), with leakage minimized to no leakage. The gap in the overlapping region can achieve a seal at a vacuum of up to about 730 mmHg, with leakage minimized to no leakage.

[0118] In other embodiments, the overlap region 348 itself does not provide a seal between the body 402 and the lumen portion 222. Instead, additional sealing elements located within the overlap region 348 (e.g., at discreet locations along the region of the lumen portion 222) narrow the gap between their respective ID and OD such that a seal is provided by the sealing elements located within the overlap region 348. In this embodiment, the seal location between the lumen portion 222 and the body 402 can be positioned more proximally with respect to certain tortuous regions of the anatomy. For example, the proximal region of the lumen portion 222 can have a deliberate stepwise increase in outer diameter, which narrows the gap between the OD of the lumen portion 222 and the ID of the body 402. This stepwise increase in the outer diameter of the lumen portion 222 can be positioned with respect to the entire length of the lumen portion 222 such that the seal region between the two components avoids forming a sharp turn. For example, the seal region can include the proximal region of the lumen portion 222 at a distance from the distal tip of the catheter, and this seal region can be designed to remain within the descending aorta DA as the distal region of the lumen portion 222 is advanced through the aortic arch, into the brachiocephalic trunk BT, the right common carotid artery RCC, until and beyond the level of the petrous portion of the internal carotid artery. When the distal end of the catheter is positioned, for example, within the M1 region of the MCA, keeping the seal region below the level of the aortic arch depends on the length of the lumen portion 222 as well as the length and position of the sealed portion on the catheter. The seal region on the lumen portion 222 can be positioned at a distance of at least about 40 cm, 45 cm, 50 cm, 55 cm, 60 cm, 65 cm, 70 cm from the distal tip of the catheter, up to about 75 cm from the distal tip of the catheter.

[0119] The use of the term "seal" in the context of a catheter and a guiding sheath refers to a situation where fluid is substantially prevented from flowing from one side of the seal to the other when suction is applied. For example, a low gap between the OD of the catheter and the ID of the sheath at the seal can prevent substantial blood flow between the outer surface of the catheter and the inner surface of the sheath when suction pressure is applied through the system, and thus form a seal. A seal does not necessarily mean that the entire catheter system is sealed. For example, even when the catheter is "sealed" to the sheath, blood can still be suctioned into the lumen of the catheter and through the guiding sheath (at least until the distal end of the catheter 200 is "blocked", at which point a complete seal of the entire system may occur).

[0120] The catheter 200 is telescopically extendable relative to the sheath (and / or relative to another catheter 200) such that the distal end of the distal lumen portion 222 can reach a cerebrovascular target within, for example, the M1, M2 regions, while the proximal end of the distal lumen portion 222 remains at or below the level of a sharp bend along the insertion path. For example, the entry location of the catheter system can be in the femoral artery, and the target embolus can be distal in the right common carotid artery (RCC), for example, within the M1 segment on the right side of the middle cerebral artery. When transitioning from the descending aorta DA, the proximal region of the distal lumen portion 222 (e.g., the location of the sealing element and / or the location where the material transition to the proximal control element 230 occurs) can remain within the blood vessel near the highly tortuous anatomical structures (carotid siphon, right common carotid artery RCC, brachiocephalic trunk BT, the origin of the brachiocephalic arteries branching from the aortic arch, aortic arch AA). In most anatomical structures, the descending aorta DA is a continuous straight segment. Figure 1C The aortic arch AA is shown, which separates the ascending aorta AscA and the descending aorta DA. The most distal carotid artery from the femoral artery access point is the right common carotid artery RCC, which originates from the brachiocephalic trunk BT (or the left common carotid artery LCC, which originates from the same brachiocephalic trunk BT in some patients - the so-called "bovine anatomy"). The distal lumen portion 222 can have a length that, when inserted into the RCC, is configured to extend downward from the target location in the M1 or M2 region to the brachiocephalic trunk BT, or down to the level of the aortic arch AA, or down to the descending aorta DA, sometimes referred to herein as "below the origin" of the brachiocephalic trunk BT. This avoids the insertion of the relatively rigid proximal control element 230 or the material transition between the relatively rigid proximal control element 230 and the distal lumen portion 222 from being affected by the very sharp turns of the aortic arch or the turns at the origin of the brachiocephalic arteries. The turns of the aortic arch and the origin of the brachiocephalic arteries are typically the first sharp turns that the catheter is likely to pass through when ascending to the brain through the RCC artery. The less flexible portion of the catheter segment can avoid areas with increased tortuosity near the internal carotid artery level. The flexibility of the distal lumen portion 222 can transition toward the proximal region to approximate the flexibility of the relatively rigid proximal control element 230. The distal end of the catheter can be used to target the left cerebral circulation, while the proximal control element 230 of the catheter 200 and the material transition of the distal lumen portion 222 near the proximal control element 230 remain below the tortuous level of the brachiocephalic turn (e.g., within the aorta, near the origin of the left common carotid artery (LCC), preferably within the descending aorta DA). Similarly, the sealing region or most of the sealing region between the distal lumen portion 222 and the sheath preferably remains proximal to these sharp turns.

[0121] In some embodiments, the length of the distal lumen portion 222 may allow the distal end of the distal lumen portion 222 to reach distal to the carotid siphon and enter the cerebral portion of the internal carotid artery, while the proximal end of the distal lumen portion 222 (e.g., at its transition to the proximal control element 230, as will be described in more detail below) remains within the aorta near the origin of the brachiocephalic trunk BT, e.g., within the descending aorta DA (see Figure 2C ). In this embodiment, the length of the distal lumen portion may be between about 35 cm and 75 cm, e.g., between 45 cm and 70 cm, or 65 cm long.

[0122] The attachment region between the relatively rigid proximal control element 230 and the relatively flexible distal lumen portion 222 creates a transition in material and flexibility that may be prone to kinking. Therefore, it is preferably avoided to advance the attachment region into extreme curvatures. For example, when the catheter is advanced from a femoral artery access site, the distal lumen portion 222 may have a length that allows the attachment point to be advanced no further than the first bend of the carotid siphon, no further than the origin 610 of the brachiocephalic artery, no further than the aortic arch AA, or no further than the descending aorta DA. In some embodiments, the length of the distal lumen portion 222 is sufficient to allow the attachment point to remain within the descending aorta DA while still entering the M1 or M2 region of the neurovascular system. When the length of the distal lumen portion 222 is between about 35 cm and 75 cm or 45 cm - 70 cm or 65 cm, it is generally avoided to position the material transition within the sharp turn from the aortic arch AA to the brachiocephalic origin BT.

[0123] A seal may be formed at and / or within the overlap region 348 between the distal lumen portion 222 and the sheath body 402. It is generally desirable to position the seal between the distal lumen portion 222 and the sheath body 402 outside of the extreme curvatures of the neurovascular system. In some embodiments, the length of the distal lumen portion 222 may allow the distal end of the distal lumen portion 222 to extend distal to the carotid siphon and into the cerebral portion of the internal carotid artery, while the seal region within the sheath body 402 remains proximal to the brachiocephalic origin BT, the aortic arch AA, or within the descending aorta DA. In this embodiment, the length may be between about 35 cm and about 75 cm, between about 40 cm and about 65 cm, or greater than 40 cm up to a length less than the working length of the sheath body 402.

[0124] For Figure 2C, the length of the un-reinforced region 407 of the distal tip 406 of the sheath 400 may allow it to provide sufficient sealing force on the outer surface of the catheter 200 when negative pressure is applied. The length of the distal lumen portion 222 of the catheter 200 used in conjunction with this embodiment of the sheath 400 may be less than 60 cm, less than 50 cm, less than 40 cm, less than 35 cm, less than 30 cm to about 10 cm. For example, when the distal lumen portion 222 of the catheter 200 is used with a sheath 400 having an un-reinforced region 407 configured to seal tightly against the outer diameter of the catheter 200, the distal lumen portion 222 of the catheter 200 may be less than about 30 cm, for example, between about 10 cm and 30 cm.

[0125] The seal within the overlap region 348 may be attributed to the smaller difference between the inner diameter and the outer diameter. The proximal region of the distal lumen portion 222 may have a stepwise increased outer diameter (e.g., increased wall thickness), thereby providing a local sealing region with the inner diameter of the guiding sheath. Additionally or alternatively, the local seal may be attributed to additional sealing elements located on the outer surface of the distal lumen portion or the inner surface of the sheath body. The sealing element may include a stepwise increased diameter or a protruding feature in the overlap region. The sealing element may include one or more external ridge features. When the lumen portion is inserted into the lumen of the sheath body, one or more ridge features may be compressible. The ridge geometry may cause the sealing element to behave as an O-ring, a square ring, or other piston seal design. The sealing element may include one or more inclined surfaces that bias against the inner surface of the sheath body lumen. The sealing element may include one or more expandable members that are actuated to seal. The expandable or dilatable member may be a balloon or a covered braided structure that can expand or dilate and provide a seal between the two devices at any time (including after the catheter is positioned at the desired site). Therefore, it is not necessary to apply a sealing force to the catheter during positioning, but rather to apply or actuate it to seal after the catheter is positioned. The sealing element may be located on the outer surface of the distal lumen portion, for example, near the proximal region of the distal lumen portion, and may be located within the overlap region. More than one sealing element may be positioned along the length of the catheter.

[0126] Additional sealing elements for the distal lumen portion 222 can be cup-shaped seals, balloon-shaped seals, or disk-shaped seals formed of a soft polymer, which are positioned around the exterior of the distal lumen portion near the overlap region to provide additional sealing. The sealing element can be a thin-walled tube, the outer diameter of which substantially matches the inner diameter of the sheath body lumen. One end of the tube can be sealed to form a cup-shaped seal, or both ends can be sealed to form a disk-shaped or balloon-shaped seal. The balloon-shaped seal can include trapped air, thereby forming a collapsible space. One or more slits can be formed through the wall tube such that the balloon-shaped seal can be collapsible and more easily passed through the RHV. The balloon-shaped seal need not include slits for a less collapsible sealing element that retains trapped air. The sealing element can be adjustable to achieve sheath fit and collapse.

[0127] In some embodiments, the system can include one or more features that limit the extension of the catheter 200 relative to the sheath 400 to a specific distance such that the resulting overlap region 348 is optimal and / or prevents the catheter 200 from being over-inserted. For example, a tab can be positioned on a region of the catheter 200 such that when the catheter 200 is inserted through the sheath 400 a selected distance, the tab is sized to abut the port through which the catheter 200 is inserted, thereby preventing the catheter 200 from extending further distally through the sheath 400. The tab can also be positioned on a region of the catheter advancement element 300 to ensure optimal extension of the catheter advancement element 300 relative to the distal end of the catheter 200, thereby facilitating advancement of the catheter 200 into an intracranial vessel.

[0128] Against Figure 3 , the proximal control element 230 is configured to move the distal lumen portion 222 in a bidirectional manner through the working lumen of the guide sheath 400 such that the distal lumen portion 222 can be advanced out of the guide sheath 400 into a target position for treatment within a target vessel. In some embodiments, as Figure 3As shown, the outer diameter of the proximal control element 230 of the catheter 200 can be smaller than the outer diameter of the distal lumen portion 222 that forms the proximal spiked portion or the tethering portion of the catheter 200. The outer diameter of the proximal control element 230 being smaller than the outer diameter of the distal lumen portion 222 allows the larger-diameter working lumen of the sheath 400 to maintain a greater suction force than would otherwise be provided by the smaller-diameter lumen portion 222 of the catheter 200, or allows the working device to be delivered through the lumen with less friction. The significantly shorter length of the lumen portion 222 causes a stepwise-increasing lumen diameter between the lumen portions 222 that are in communication with the working lumen, thereby providing a significantly increased radius and lumen area for delivering the working device and / or aspirating clots, particularly as compared to other systems where the aspiration lumen extends along the entire inner diameter of the aspiration catheter. More particularly, along the entire length of the system, the total volume of the lumen area of the catheter 200 and the lumen area of the working lumen near the distal lumen portion 222 is greater than the lumen area of a large-bore catheter. Thus, the likelihood of clearing an embolus during a single aspiration attempt can be increased. More specifically, the stepwise-increasing lumen diameter along the proximal control element 230 enables a greater suction force to be achieved, thereby improving the aspiration of emboli. In addition, this configuration of the catheter 200 and the proximal control element 230 greatly reduces the time required to retract and re-advance the catheter 200 and / or the working device through the working lumen from the distal opening 408. The proximal control element 230 of the catheter 200 has a length and structure that extends through the working lumen of the sheath 400 to the proximal end of the system 100 such that the proximal control element 230 can be used to advance and retract the catheter 200 through the working lumen. However, the proximal control element 230 of the catheter 200 occupies only a small portion of the lumen space of the system 100, such that the increased lumen area is available for aspiration and / or delivery of the working device. The stepwise-increasing lumen diameter also increases the annular area available for forward flushing with contrast agent, saline, or other solutions, while devices such as a microcatheter or other devices can be coaxially positioned within the lumen portion 222 of the catheter 200 and / or the working lumen. This can improve the convenience and ability to perform angiography during device navigation.

[0129] In one embodiment, the distal lumen portion 222 of the catheter 200 is configured to be flexible and lubricious so as to be safely navigated to a target location. The distal lumen portion 222 is kink-resistant and collapse-resistant under high suction forces so as to be able to effectively aspirate clots. The lumen portion 222 may have increasing flexibility towards the distal end, with a smooth material transition along its length to prevent any kinking, angulation or sharp bends in its structure, e.g., during highly angulated navigation such as 90° turns or greater up to 180° turns, such as at the aortic-iliac junction, at the origin of the left subclavian artery LSA leading from the aorta AA, at the origin of the brachiocephalic (innominate) artery BT leading from the ascending aorta AscA, and at many other peripheral locations, such as in the carotid siphon. The distal lumen portion 222 may transition from less flexible near its junction with the proximal control element 230 to greater flexibility at its most distal end. For example, a first portion of the distal lumen portion 222 may be formed of a material having a material hardness of 72D along a first length, a second portion may be formed of a material having a material hardness of 55D along a second length, a third portion may be formed of a material having a material hardness of 40D (e.g., Pebax or MX1205) along a third length, a fourth portion may be formed of a material having a material hardness of 35D along a fourth length, a fifth portion may be formed of a material having a material hardness of 25D along a fifth length, a sixth portion may be formed of a material having a material hardness of 85A (e.g., Tecoflex) along a sixth length, and the most distal portion of the catheter may be formed of a material having a material hardness of 80A (e.g., Tecoflex). In some embodiments, the most distal portion of the distal lumen portion 222 of the catheter 200 may be formed of a material having a material hardness of 62A (e.g., Tecothane). Thus, the distal lumen portion 222 transitions from less flexible near its junction with the proximal control element 230 to greater flexibility at its most distal end, where, for example, the distal tip of the catheter advancement element 300 may extend from the distal end of the catheter 200. Other operative catheters described herein may have a similar construction providing variable relative stiffness transitioning from the proximal end to the distal end of the catheter, as described elsewhere herein. The change in flexibility from the proximal end to the distal end of the distal lumen portion 222 may be achieved by any of a variety of methods.

[0130] The distal lumen portion 222 may include two or more layers. In some embodiments, the distal lumen portion 222 includes an inner lubricious liner, a reinforcement layer, and an outer sleeve layer, which will be described in detail separately.

[0131] The lubricious inner liner can be a PTFE liner having one or more thicknesses along the flexible variable portion. The PTFE liner can be a tubular liner formed by dip coating or thin film casting onto a removable mandrel (such as a silver-plated copper wire known in the art). Various layers of different thicknesses can be applied. For example, a PTFE etch base layer having a thickness of about 0.005” can be formed. A second intermediate layer can be formed over the base layer, the intermediate layer being Tecoflex SG-80A having a thickness of about 0.0004”. A third top layer can be formed over the intermediate layer, the top layer being Tecoflex SG-93A having a thickness of about 0.0001” or less. Before removing the mandrel by axial elongation, a reinforcement layer and / or reinforcing fibers can be applied to the inner liner, followed by application of an outer sleeve layer and / or additional outer coating.

[0132] The reinforcement layer is a generally tubular structure formed by, for example, wound tapes or coils or braids. The material for the reinforcement structure can be stainless steel (such as 304 stainless steel), nitinol, cobalt-chrome alloy, or other metal alloys that provide a desired combination of strength, flexibility, and crush resistance. In some embodiments, the distal lumen portion 222 has a reinforcement structure that is a nitinol tape wrapped into a coil. For example, the coil reinforcement can be a nitinol tapered tape set to a specific inner diameter (such as an inner diameter of 0.078” to 0.08”) and having a pitch (such as between 0.012” and 0.016”). The tape can be 304 stainless steel (such as, about 0.012”×0.020”). The coil can be heat set before being transferred onto the catheter. The pitch of the coil can increase from the proximal end to the distal end of the distal lumen portion 222. For example, there can be a gap between the ribbon coils, and the size of the gap can increase as it moves toward the distal end of the distal lumen portion 222. For example, near the proximal end of the distal lumen portion 222, the size of the gap between the ribbon coils can be a gap of about 0.016”, while near the distal end, the size of the gap between the ribbon coils can be larger, such as a gap of 0.036”. This variation in pitch provides increased flexibility near the most distal end of the distal lumen portion 222. The distal lumen portion 222 can additionally incorporate one or more reinforcing fibers (see Figures 8B - 8C ), which are configured to prevent elongation of the coil, as will be described in more detail below. The reinforcement structure can include a variety of materials and / or designs to similarly vary the flexibility along the length of the distal lumen portion 222.

[0133] The outer sleeve layer can be composed of discontinuous portions of polymers having different hardnesses, compositions, and / or thicknesses to vary the flexibility along the length of the distal lumen portion 222.

[0134] At least a portion of the outer surface of the catheter 200 may be coated with a lubricious coating, such as a hydrophilic coating. In some embodiments, the coating may be on the inner surface and / or the outer surface to reduce friction during tracking. The coating may include a variety of materials known in the art. The proximal control element 230 may also be coated to improve tracking through the working lumen. Suitable lubricious polymers are well known in the art and may include silicones and the like, hydrophilic polymers such as high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides, polyvinylpyrrolidone, polyvinyl alcohol, hydroxyalkylcellulose, alginates, sugars, caprolactone, HYDAK coatings (such as B-23K, HydroSleek), etc., and mixtures and combinations thereof. The hydrophilic polymers may be mixed with each other or with a certain amount of water-insoluble compounds (including certain polymers) to produce a coating having suitable lubricity, binding, and solubility.

[0135] In some embodiments, the distal lumen portion 222 includes two or more layers. In some embodiments, the distal lumen portion 222 includes an inner lubricious lining, a reinforcing layer, and an outer sleeve layer. The outer sleeve layer may be composed of discontinuous portions of polymers having different hardnesses, compositions, and / or thicknesses to vary the flexibility along the length of the distal lumen portion 222. In one embodiment, the lubricious inner lining is a PTFE lining having one or more thicknesses along the flexibility variable portion. In one embodiment, the reinforcing layer is a generally tubular structure formed, for example, by wound bands or coils or braids. The material for the reinforcing structure may be stainless steel (such as 304 stainless steel), nitinol, cobalt-chromium alloy, or other metal alloys that provide a desired combination of strength, flexibility, and crush resistance. In one embodiment, the reinforcing structure includes a variety of materials and / or designs to also vary the flexibility along the length of the distal lumen portion 222. In one embodiment, the outer surface of the catheter 200 is coated with a lubricious coating, such as a hydrophilic coating. The proximal control element 230 may also be coated to improve tracking through the working lumen. Suitable lubricious polymers are well known in the art and may include silicones, etc., hydrophilic polymers such as high density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides, polyvinylpyrrolidone, polyvinyl alcohol, hydroxyalkylcellulose, alginates, sugars, caprolactone, etc., and mixtures and combinations thereof.

[0136] Against Figures 2A - 2B, the distal lumen portion 222 of the catheter 200 may have a plurality of radiopaque markers. A first radiopaque marker 224a may be positioned near the distal tip region to assist in the navigation and proper positioning of the tip under fluoroscopy. Additionally, the proximal region of the catheter 200 may have one or more proximal radiopaque markers 224b such that the overlap region 348 can be visualized as the relationship between the radiopaque marker 411 on the guide sheath 400 and the radiopaque marker 224b on the catheter 200. The proximal region of the catheter 200 may also have one or more radiopaque markers to provide visualization, for example, of the proximal opening of a single lumen leading to the catheter, as will be described in more detail below. In one embodiment, the two radiopaque markers (the marker 224a at the distal tip and the more proximal marker 224b) are different to minimize confusion in the fluoroscopic image. For example, the catheter proximal marker 224b may be a single band, while the marker 411 on the guide sheath 400 may be a double band, and any markers on the working device delivered through the distal access system may have another type of band or marker. The radiopaque markers 224 of the distal lumen portion 222, particularly those near the distal tip region navigating highly tortuous anatomy, may be relatively flexible such that they do not affect the overall flexibility of the distal lumen portion 222 near the distal tip region. Compared to other types of radiopaque markers used in devices where flexibility is not as critical, the radiopaque markers 224 may be tungsten-loaded or platinum-loaded markers. In some embodiments, the radiopaque marker may be a tungsten-loaded PEBAX band having a hardness of 35D.

[0137] As Figures 8B - 8CAs best shown, at least one reinforcing fiber 801 can be incorporated within the wall of the distal lumen portion 222 to prevent elongation of the coiled reinforcing layer 803. The fiber 801 can be located between the liner layer 805 and the reinforcing layer 803. The fiber 801 can extend along the longitudinal axis A of the catheter 200 from the proximal region of the distal lumen portion 222 to the distal region of the distal lumen portion 222. The proximal end of the fiber 801 can be coupled to a region of the distal lumen portion 222 near its connection to the proximal control element 230. The distal end of the fiber 801 can terminate near the distal end of the distal lumen portion 222. The distal end of the fiber 801 can be captured between the distal marker band 224a and the end of the reinforcing layer 803. The distal marker band 224a can be fully encapsulated between the inner liner 805 and the outer sleeve 807. In some embodiments, the distal end of the fiber 801 extends distally beyond the last coil of the reinforcing layer 803 that extends beneath the marker band 224a and then loops around the band 224a in the proximal direction. Thus, the free end of the fiber 801 is captured beneath the reinforcing layer 803 and the marker band 224a. Accordingly, the reinforcing fiber 801 terminates at the location where the reinforcing layer 803 terminates, leaving a length between about 10 cm and 12 cm of the most distal tip region un-reinforced. The catheter 200 can include multiple reinforcing fibers 801 extending longitudinally along the distal lumen portion 222, such as two, three, four or more fibers 801 distributed around the circumference of the distal lumen portion 222 and parallel to each other and parallel-aligned with the axial axis A of the catheter 200. The reinforcing fibers 801 can also terminate at a location further distal than the distal end marker 224a, or at a location closer to the distal end marker 224a. The material of the reinforcing fibers 801 can vary and include, but is not limited to, various high-strength polymers such as polyester, PEEK, and other similar materials.

[0138] The distal lumen portion 222 of the catheter 200 can have a proximal control element 230 that is coupled to a single lumen of the distal lumen portion 222 near the proximal opening. The distal lumen portion 222 and the proximal control element 230 can be attached to each other by a coupling band 901 (see Figures 9A - 9C)。The proximal end 905 of the coupling band 901 can be attached to the distal end of the proximal control element 230, and the distal end of the coupling band 901 can be attached to the distal lumen portion 222. The proximal end 905 of the coupling band 901 can include a groove 907 that is configured to be welded to the proximal control element 230 of the catheter 200. The catheter 200 can include a strain relief along the scraping length, such as tungsten-loaded PEBAX. The distal end of the cuttable coupling band 901 can be formed into a plurality of helical portions 903. These helical portions 903 are configured to be interspersed with the coils of the reinforcement layer 803 at the proximal region of the distal lumen portion 222. The size of the gap between the helical portions 903 of the coupling band 901 can be substantially similar to the size of the gap between the coils of the reinforcement layer 803, such that they can be neatly interspersed with each other without any local areas of increased wall thickness due to overlap. The thickness of the helical portions 903 can, but need not, be similar to the thickness of the band forming the reinforcement layer 803. For example, the coiled reinforcement layer 803 can be formed from a Nitinol band having a thickness of about 0.003". The coupling band 901 can have a wall thickness of about 0.003", such that the helical portions 903 and the coils of the reinforcement layer 803 can be similar in material thickness. This similarity in material thickness between the coils and the helical portions 903 contributes to a generally uniform outer profile that can be kept to a minimum and avoids a significantly increased wall thickness in this coupling region. The low-profile proximal end of the distal lumen portion 222 helps to maximize the inner diameter while keeping the outer diameter as small as possible, e.g., such that the inner diameter of the guide sheath is minimized (e.g., less than about 0.113" or about 0.107"). The coupling band 901 can include a hole 911 that passes through an intermediate region 909 and is configured to receive the proximal end of the reinforcing fiber 801 that extends longitudinally through the distal lumen portion 222. The overlap region between the distal end of the proximal control element and the distal lumen portion 222 can vary, but can be at least about 5 mm, at least about 7 mm, at least about 10 mm to provide a smooth and uniform transition. The overlap between the proximal control element and the distal lumen portion 222 can be from about 5 mm to about 15 mm.

[0139] As mentioned, the distal end of the proximal control element 230 can be welded to the proximal end 905 of the coupling band 901. In some embodiments, the distal region of the proximal control element 230 is thinned by pins in place and flat in other locations. The proximal control element 230 can be a stainless steel strip (e.g., 0.012”×0.020” or 0.014”×0.020” along most of its length). The distal region of the proximal control element 230 can have a discontinuous taper that allows the thickness of the strip to transition from a thickness of 0.012” or 0.014” to a thickness that matches or is not significantly different from the thickness of the helical portion 903 on the coupling band 901 attached to the proximal region of the distal lumen portion 222. The discontinuous taper can include flat lengths defined at the proximal and distal ends with decreasing lengths. This flat length allows for a more uniform minimum material thickness between the distal lumen portion 222 and the proximal control element 230, thus avoiding introducing vulnerable points that are more prone to kinking. For example, the distal region of the proximal control element 230 can have a first taper length and a second taper length, where the thickness of the first taper length transitions from 0.012” to 0.008” thickness, and the second taper length transitions from the thickness of the flat length to about 0.003”. In other embodiments, the distal region of the proximal control element 230 can have a first taper length and a second taper length, where the thickness of the first taper length transitions from 0.014” to 0.010” thickness, and the second taper length transitions from the thickness of the flat length to about 0.003”. The thickness of the helical portion 903 of the coupling band 901 can match this end thickness of the proximal control element 230. The lengths of the tapered and flat portions can vary. In some embodiments, the first taper length can be about 0.12 cm, the flat length can be about 0.2 cm, and the second taper length can be about 0.15 cm. The uniform thickness along this flat length provides a useful target in manufacturing the catheter. The catheter does not have to incorporate the ribbon-like proximal control element 230 and can have any of the various configurations described elsewhere herein.

[0140] As previously mentioned, the proximal control element 230 is configured to allow the catheter 200 to be advanced distally and retracted proximally through the working lumen of the guide sheath 400, including exiting through the distal opening 408. In one embodiment, the length of the proximal control element 230 is longer than the entire length of the guide sheath 400 (from the distal tip to the proximal valve), e.g., about 5 cm to 15 cm longer. The length of the body 402 can be in the range of 80 to 90 cm or up to about 100 cm or up to about 105 cm, and the length of the proximal control element 230 can be between 90 and 100 cm.

[0141] Against Figure 3, the proximal control element 230 may include one or more markers 232 to indicate the overlap between the distal lumen portion 222 of the catheter 200 and the sheath body 402 and the overlap between the distal lumen portion 222 of the catheter 200 and other interventional devices that may extend through the distal lumen portion 222. At least the first marker 232a may be an RHV proximity marker positioned such that when the marker 232a aligns with the sheath proximal hemostatic valve 434 during insertion of the catheter 200 through the guiding sheath 400, the catheter 200 is positioned at the most distal position with the minimum overlap length required to form a seal between the catheter 200 and the working lumen. At least the second marker 232b may be a fluoroscopic guard marker that may be positioned on the control element 230 and at a distance from the distal tip of the distal lumen portion 222. In some embodiments, the marker 232 may be positioned approximately 100 cm from the distal tip of the distal lumen portion 222.

[0142] The proximal control element 230 may include a gripping feature such as a tab 234 on the proximal end to facilitate gripping and advancing or retracting the proximal control element 230. The tab 234 may be coupled to one or more other components of the system, as will be described in more detail below. The proximal tab 234 may be designed to be easily recognizable among any other devices that may be inserted into the sheath proximal valve 434, such as a guide wire or a retrievable stent device wire. A portion of the proximal control element 230 and / or the tab 234 may be colored bright or marked bright to distinguish it from a guide wire, a retrievable stent tether, etc. In cases where multiple catheters 200 are used together in a nested manner to reach more distal locations within the brain, each proximal control element 230 and / or tab 234 may be color-coded or otherwise marked to clearly show the operator which proximal control element 230 of which catheter 200 it is coupled to. The proximal portion 366 of the catheter advancement element 300 may also include a color to distinguish it from the proximal control element 230 of the catheter 200.

[0143] The tab 234 may be integrated with or supplemental to a proximal hub coupled to the proximal end of the control element 230. For example, as will be described in more detail below, the proximal control element 230 may be a hypotube having a lumen. The lumen of the hypotube may be in fluid communication with the proximal hub at the proximal end of the control element 230 such that suction and / or fluid may be delivered through the hypotube via the proximal hub. The proximal control element 230 may also be a solid element and need not include a lumen for guiding suction to the distal end of the catheter 200.

[0144] The proximal control element 230 can be configured to have sufficient stiffness to allow for the advancement and retraction of the distal lumen portion 222 of the catheter 200, but also be flexible enough to navigate through the brain anatomy as needed without kinking. The configuration of the proximal control element 230 can vary. In some embodiments, similar to a typical catheter device, the proximal control element 230 can be a tubular element having an outer diameter that is substantially the same as the outer diameter of the distal lumen portion 222. In other embodiments, the outer diameter of the proximal control element 230 is sized to avoid occupying too much lumen area within the lumen of the guide sheath 400 to provide a stepped increase in the inner diameter for aspiration.

[0145] The proximal control element 230 can be a solid wire having a circular, rectangular, trapezoidal, D-shaped, or oval cross-sectional shape (see Figures 4A - 4G ). The proximal control element 230 can be a flat ribbon having a rectangular cross-sectional shape as shown in Figure 4A . The flat ribbon can also have a square, rectangular, or other cross-sectional shape. The ribbon can be bent into a circle, oval, C-shape, or quarter circle, or other cross-sections along an arc. In this way, the inward-facing surface of the ribbon can be substantially flat, and the outward-facing surface of the ribbon (i.e., the surface configured to abut the inner diameter of the access sheath through which it extends) can be substantially curved (see Figures 4F - 4G ). The curvature of the surface can substantially match the curvature of the inner surface of the access sheath. The resulting cross-sectional shape of such a ribbon can be generally trapezoidal. The overall dimensions of the ribbon can vary depending on its cross-sectional shape and the dimensions of the distal lumen portion. A catheter 200 sized 0.054” can have a proximal control element 230 with a trapezoidal or D-shaped cross-section. The inward-facing flat surface can have a width of approximately 0.020”, and in the case of a trapezoidal embodiment, the outward-facing curved surface can extend along an arc of approximately 0.030” in length. A catheter 200 sized 0.070” can have a proximal extension with a trapezoidal or D-shaped cross-section, and the width of the inward-facing flat surface is slightly larger, e.g., approximately 0.025”, and in the case of a trapezoidal embodiment, the outward-facing curved surface can extend along an arc of approximately 0.040” in length. A catheter 200 sized 0.088” can have a proximal extension with a trapezoidal or D-shaped cross-section, the width of the inward-facing flat surface is approximately 0.035”, and the outward-facing curved surface of the trapezoidal embodiment can extend along an arc of approximately 0.050” in length.

[0146] The proximal control element 230 can be a hollow wire having a lumen 235 extending through it, such as in Figure 4BThe hypotube shown. The hypotube may have an oval or circular shape. In one embodiment, the proximal control element 230 is a stainless steel strip having dimensions of approximately 0.012"×0.020". In one embodiment, the proximal control element 230 is a stainless steel strip having dimensions of approximately 0.014"×0.020". In one embodiment, the proximal control element 230 is a round wire having dimensions of 0.014" to 0.018". In another embodiment, the proximal control element 230 is a strip having dimensions ranging from 0.010" to 0.015" thick and 0.015" thick to 0.025" thick. In one embodiment, the proximal control element 230 is a hypotube formed from a flat rigid material strip that is rolled into a tubular shape to have a lumen 235. In some embodiments, the proximal control element 230 can be formed from a flat stainless steel strip and rolled into a hypotube prior to modifying the hypotube to an elliptical cross-sectional shape such that the proximal control element 230 has a wall thickness of approximately 0.007", an inner diameter of approximately 0.004", and an outer diameter of approximately 0.018". The elliptical hypotube can maintain an inner diameter of at least 0.001" along at least the first dimension, and an outer diameter of at least 0.015" along at least the first dimension. In one embodiment, the material of the proximal control element 230 is a metal such as stainless steel or nickel titanium alloy, and a plastic such as any of a variety of polymers.

[0147] In one embodiment, the proximal control element 230 is a stainless steel hypotube having an elliptical cross-sectional shape (see Figure 4B ). The oval tubular shape can increase the column strength, pushability and kink resistance of the proximal control element 230 to improve advancement through tortuous anatomical structures. The cross-sectional area of ​​the oval hypotube minimizes the effect of the catheter 200 on the movement of other tools through the working lumen of the sheath 400. Figure 4C Shown is a cross-sectional view of the working lumen of a sheath 400 having a proximal control element 230 extending therethrough. The proximal control element 230 has a rectangular cross-sectional shape. Figure 4D A cross-sectional view of a working lumen is shown having an elliptical hypotube proximal control element 230 and a catheter advancement element 300 extending therethrough. Figure 4EA comparison of surface area between a rectangular band and an oval hypotube is shown. The oval hypotube has a smaller surface area than the rectangular band, thereby allowing a greater flow through the working lumen, for example, during application of a suction force. The material, size, and shape of the proximal control element 230 may be selected based on the material, size, and shape of the distal lumen portion 222. For example, the proximal control element 230 may be a rectangular band of 340 stainless steel that is 0.012" x 0.020", and the distal lumen portion 222 may have an inner diameter of approximately 0.054" to approximately 0.072". In other embodiments, the proximal control element 230 may be a rectangular band of 340 stainless steel that is 0.014" x 0.020", and the distal lumen portion 222 may have an inner diameter of approximately 0.088". The additional weight of the stainless steel band 230 may be used to advance catheters of larger inner diameters without kinking.

[0148] Now targeting Figures 5A - 5F , the joint between the distal lumen portion 222 of the catheter 200 and the proximal control element 230 can be configured to allow a smooth transition of flexibility between the two portions without creating kinks or weak points. The smooth transition of the joint between the distal lumen portion 222 and the proximal control element 230 also allows the device to smoothly pass through the connected internal lumen formed by the working lumen of the guide sheath 400 and the lumen 223 of the lumen portion 222 of the catheter 200. In one embodiment, the distal lumen portion 222 has a transition portion 226 near the proximal opening leading to a single lumen, and the lumen portion 222 is connected to the proximal control element 230 at the transition portion 226 (see Figure 5A)。The transition portion 226 may have an angled cut such that there is no sudden stepped transition from the working lumen of the guide sheath 400 to the inner lumen 223 of the catheter 200. The angled cut may be substantially flat. In an alternative embodiment, the angled cut is curved or stepped to provide a more gradual transition zone. The proximal region of the distal lumen portion 222 may be angled obliquely relative to the longitudinal axis of the catheter 200 such that the proximal end and the proximal opening leading to the lumen are at an angle other than 90° relative to the longitudinal axis of the catheter 200, such as between approximately 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45° up to less than 90°. The proximal region of the distal lumen portion 222 may also be substantially perpendicular to the longitudinal axis of the catheter 200 such that the proximal end and the proximal opening leading to the lumen are substantially at 90° to the longitudinal axis of the catheter 200. Similarly, the distal region of the distal lumen portion 222 may be angled obliquely relative to the longitudinal axis of the catheter 200 such that the distal end and the distal opening from the lumen 223 are at an angle other than 90° relative to the longitudinal axis of the catheter 200, such as between approximately 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45° up to less than 90°. The distal region of the distal lumen portion 222 may also be substantially perpendicular to the longitudinal axis of the catheter 200 such that the distal end and the distal opening leading to the lumen are substantially at 90° to the longitudinal axis of the catheter 200.

[0149] The proximal control element 230 may be coupled to the proximal region of the catheter 200 and / or may extend along at least a portion of the distal lumen portion 222 such that the proximal control element 230 is coupled to the distal lumen portion 222, for example, by a coupling band 901, distal to the proximal end that defines the proximal opening leading to the lumen. The proximal control element 230 may be coupled to the distal lumen portion 222 by various mechanisms including bonding, welding, gluing, clamping, threading, tethering, or tying one or more components that make up the proximal control element 230 and / or portion 222. The distal lumen portion 222 and the proximal control element 230 may be joined by a welded bond, a mechanical bond, an adhesive bond, or some combination thereof. In some embodiments, the proximal control element 230 and the lumen portion 222 are joined together by sandwiching the proximal control element 230 between the layers of the distal lumen portion 222. For example, the proximal control element 230 may be a hypotube or rod with a distal end that is scored, ground, or cut such that the distal end can be laminated or otherwise attached to the layers of the catheter portion 222 near the proximal region. The scored length of the proximal control element 230 may be about 7 mm and may incorporate a tungsten-loaded Pebax strain relief along that length. The overlap region between the distal end of the proximal control element 230 and the lumen portion 222 may be at least about 1 cm. This type of coupling allows for a smooth and uniform transition from the proximal control element 230 to the lumen portion 222.

[0150] Still targeting Figures 5A - 5F , the transition portion 226 of the distal lumen portion 222 may lead to a proximal tail 238, which extends a length proximal to the transition portion 226. In some embodiments, the proximal tail 238 has a substantially curved cross-sectional geometry. For example, the proximal tail 238 may extend between about 20 degrees and about 90 degrees along the arc of the longitudinal axis of the catheter 200. In some embodiments, the proximal tail 238 is bent to form a funnel shape, and helps to load and reload the catheter propulsion element 300 into the lumen of the catheter 200. In other embodiments, the edge of the proximal tail 238 is bent so that the proximal tail 238 is not substantially flat. The curved shape may vary, including a teardrop shape, thereby allowing the catheter propulsion element 300 to smoothly transition and better load / reload into the lumen, and avoid being able to abut and capture the flat edge of the component when the component is inserted. In other embodiments, the proximal tail 238 is substantially flat. When the device is forced to bend, the proximal tail 238 can provide a smooth transition between the distal lumen 222 and the proximal control element 230. This can reduce the likelihood of kinking and aid in pushing against resistance.

[0151] The size of the proximal tail 238 can vary. Compared to the width of the proximal control element 230, Figures 5A - 5F The proximal tail 238 shown in the figure is relatively wide, and can then have a greater length without negatively affecting the ability of other devices to be inserted into the lumen through the proximal opening at the transition region 226. In other embodiments, the proximal tail 238 defined by the area that is not supported by the coils of the reinforcement layer 803 and is located proximal to the coupling band 901 can have a shorter length. The width of the proximal tail 238 can taper along the shorter length to the width of the proximal control element 230. The tapered shorter proximal tail 238 can alleviate the problem of inserting tools into the proximal opening. In general, the wider proximal tail 238 can be longer than the proximal tail 238 that tapers down to the width of the proximal control element 230.

[0152] The proximal region of the distal lumen portion 222 may incorporate one or more markers to provide visualization under fluorescence during loading / reloading of the catheter advancement element 300. For example, the proximal region may include a Pebax region (e.g., 35D) loaded with tungsten (80%) to achieve radiopacity. In some embodiments, the proximal tail 228 and / or transition portion 226 defining the proximal opening into the lumen of the lumen portion 222 may be coated or embedded with a radiopaque material so that the opening to the lumen can be fully visualized during use. The radiopaque material embedded in the proximal region causes a step-like increase in the outer diameter.

[0153] The distal end of the proximal control element 230 and / or the distal lumen 222 may have features that facilitate mechanical engagement during welding, such as a textured surface, protruding features, or cutout features. During the thermal welding process, these features will facilitate mechanical bonding between the polymer distal lumen 222 and the proximal control element 230. For example, Figures 6A - 6F As shown, the proximal end of the distal lumen portion 222 may include a short mating sheath 240 coupled to the proximal edge 221 of the distal lumen portion 222. The sheath 240 may include an internal lumen extending between a proximal opening 242 and a distal opening 241. The distal end of the proximal control element 230 may be inserted through the proximal opening 242 and into the internal lumen of the sheath 240 to couple the proximal control element 230 to the distal lumen portion 222. In some embodiments, the proximal control element 230 may be coupled to the distal lumen portion 222 such that the distal opening 231 of the hypotube forming the proximal control element 230 may communicate with the lumen 223 of the distal lumen portion 222, for example, through the distal opening 241 of the sheath 240. Similar to the proximal tail 238, the sheath 240 may also provide a transition between the distal lumen portion 222 and the proximal control element 230. The distal lumen portion 222 need not include a mating sheath 240 coupled to the proximal control element 230. For example, the distal end of the proximal control element 230 may be inserted through the wall of the proximal tail 238 at the proximal end of the distal lumen portion 222 (see Figure 5A , 5E -5F). The distal end of the proximal control element 230 can extend along the length of the proximal tail 238 and along at least a portion of the length of the wall of the distal lumen portion 222.

[0154] The lumen 222 of the catheter 200 may have a uniform diameter or wall thickness from the proximal end to the distal end, or the lumen 222 may have different outer diameters or wall thicknesses along its length. For example, the distal end of the distal lumen 222 may have a smaller outer diameter than the more proximal region of the distal lumen 222. Figures 5A - 5B , 5E-5F and Figures 6A - 6B , 6E-6F and Figure 8A The distal lumen 222 having a distal tubular region, or a distal tube 245 having a smaller outer diameter, and a proximal tubular region or a proximal tube 246 having a larger outer diameter are shown. The distal tube 245 transitions to the proximal tube 246 via a step-up 247. Figure 5A and 6AAs shown, the inner diameter of the distal tube 245 and the inner diameter of the proximal tube 246 are substantially the same, thereby providing a smooth inner wall surface for the lumen 223. The outer diameter of the distal tube 245 can be smaller than the outer diameter of the proximal tube 246. The stepped enlargement 247 is formed by the transition of the wall thickness between the distal tube 245 and the proximal tube 246. In some embodiments, the outer diameter of the distal tube 245 can be from about 0.080” to about 0.084”, while the outer diameter of the proximal tube 246 can be from about 0.087” to about 0.088”. In other embodiments, the outer diameter of the proximal tube 246 can be from 0.106” to about 0.107”. The relative lengths of the proximal tube 246 and the distal tube 245 can vary, as described elsewhere herein. For example, the proximal tube 246 can form a proximal seal area, which is a cylindrical section with a length of about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, up to about 10 mm or 15 mm. The proximal seal area of the proximal tube 246 can have a larger OD compared to the OD of the distal tube. In some embodiments, the distal tube can have an OD of about 0.082”, and the proximal tube 246 at the proximal seal area can have an OD of about 0.087”. In other embodiments, the distal tube can have an OD of about 0.102”, and the proximal tube 246 at the proximal seal area can have an OD of about 0.105”.

[0155] At least a portion of the wall of the proximal tube 246 with a larger outer diameter can be discontinuous such that it includes a slit 236 (see Figures 5A - 5C , 5E - 5F, 6A - 6C and 6E - 6F). The slit 236 can extend a certain distance along the length of the proximal tube 246. The slit 236 can extend from the edge 221 of the proximal tube 246 for at least about 2 cm in length of the proximal tube 246. The slit 236 can, but need not, extend along the entire length of the proximal tube 246 to the position of the stepped enlargement 247. Additionally, the proximal tube 246 can include more than one slit 236. The slit 236 can be located at a position in the proximal tube 246 with a larger diameter that is opposite to the position where the distal end of the proximal control element 230 is coupled to the wall of the distal lumen portion 222. In this way, the distal end of the proximal control element 230 embedded in the wall of the proximal tube 246 is positioned opposite to the slit 236 (see Figure 5C and 6C ). The slit 236 can be positioned around the proximal tube 246 at another position.

[0156] The slit 236 may allow the proximal tube 246 to expand slightly such that the end portions of the walls forming the slit 236 separate, thereby creating a gap therebetween. For example, when inserting the catheter 200 through the working lumen of the sheath 400, the outer diameter may be received in a sliding fit manner such that at least the overlapping region 348 is maintained. When applying a suction force through the working lumen, for example, by applying a suction force from a suction source coupled to the proximal end 403 of the guiding sheath 400, the seal provided at the overlapping region 348 may be enhanced by slightly widening the gap formed by the slit 236. Since the outer surface of the wall of the catheter 200 may press against the wall of the working lumen, this slight expansion provides a better seal between the outer diameter of the proximal tube 246 and the inner diameter of the working lumen of the sheath 400, thereby creating a tight fit between the catheter 200 and the sheath 400. This improved seal between the outer surface of the catheter 200 and the inner surface of the working lumen minimizes the infiltration of blood from the blood vessel directly into the working lumen through the distal opening 408. Thus, the larger outer diameter of the proximal tube 246 in combination with the slit 236 may enhance the seal between the catheter 200 and the sheath 400 by accommodating changes in the inner diameter of the sheath. The slit 236 may effectively increase the outer diameter of the proximal tube 246 depending on whether the walls forming the slit 236 are separated by a certain distance. The walls forming the slit 236 may separate from each other and increase the width of the slit. The outer diameter of the proximal tube 246 including the increased width when the walls forming the slit 236 are separated may be of the same or greater size compared to the inner diameter of the sheath into which the proximal tube 246 is inserted. This allows a single catheter to be compatible with a wider range of inner diameters. In some embodiments, when the walls forming the slit 236 are adjacent to each other and there is no gap, the outer diameter of the proximal tube 246 may be 0.081” or about 0.100”. When the walls forming the slit 236 are separated by the maximum distance, the outer diameter of the proximal tube 246 may increase to about 0.087” or increase to about 0.106”. Additionally, the increased wall thickness of the proximal tube 246 allows for a more robust junction to be formed between the distal lumen portion 222 and the proximal control element 230 of the catheter.

[0157] Additionally or alternatively, the distal tip 406 of the sheath 400 may include one or more features to improve the seal between the inner diameter of the working lumen of the sheath 400 and the outer diameter of the proximal region of the catheter 200.

[0158] Catheter advancement element

[0159] The distal access system 100 may, but need not, include a catheter advancement element 300 for delivering the catheter 200 to a distal anatomy. Similarly, in addition to the catheter 200 described herein, the catheter advancement element 300 can be used together to advance other catheters. For example, the catheter advancement element 300 can be used to deliver a 5MAX reperfusion catheter (Penumbra, Inc., Alameda, Calif.) for clot removal in a patient with acute ischemic stroke or other reperfusion catheters known in the art. Although the catheter advancement element 300 is described herein with reference to the catheter 200, the catheter advancement element 300 can be used to advance other catheters and is not intended to limit its use.

[0160] The distal access system 100 can provide rapid and simple access to a distal target anatomy, particularly the tortuous anatomy of the cerebral vasculature. The flexibility and deliverability of the distal access catheter 200 allow the catheter 200 to assume the shape of the tortuous anatomy and avoid applying straightening forces that create new anatomy. The distal access catheter 200 can do this even when the catheter advancement element 300 extends through its lumen. Thus, the flexibility and deliverability of the catheter advancement element 300 are comparable to or better than those of the distal lumen portion 222 of the distal access catheter 200, as both are configured to reach the middle cerebral artery (MCA) circulation without straightening the curves of the anatomy along the path.

[0161] The catheter advancement element 300 can include a non-expandable flexible elongate body 360 coupled to a proximal portion 366. The catheter advancement element 300 and the catheter 200 described herein can be configured for a rapid exchange or integral exchange method. For example, the flexible elongate body 360 can be a tubular portion that extends along the entire length of the catheter advancement element 300 and can have a proximal opening that begins at the lumen of the flexible elongate body 360 and is configured to extend outside the patient during use. Alternatively, the tubular portion can have a proximal opening that is positioned such that the proximal opening remains inside the patient during use. The proximal portion 366 can be a proximal element that is coupled to and extends proximally from the distal tubular portion. The proximal opening that begins at the tubular portion can be positioned near the location where the proximal element is coupled to the tubular portion. Alternatively, the proximal portion 366 can be a proximal extension of the tubular portion whose length extends to a proximal opening near the proximal end of the catheter advancement element 300 (i.e., outside the patient).

[0162] The configuration of the proximal portion 366 can be varied. In some embodiments, the proximal portion 366 is only a proximal extension of the flexible elongated body 360, which has no significant changes in structure, but changes significantly in flexibility. For example, the proximal portion 366 transitions from the extremely high flexible distal region of the catheter propulsion element 300 to the less flexible proximal region of the catheter propulsion element 300. The proximal portion 366 provides a relatively rigid proximal end, which is suitable for manipulating and twisting the more distal region of the catheter propulsion element 300. In other embodiments, the proximal portion 366 is a hypotube. The hypotube may be exposed or may be coated with a polymer. In other embodiments, the proximal portion 366 may be a polymer portion enhanced by a coiled band. The proximal portion 366 may have an outer diameter identical to the flexible elongated body, or may have an outer diameter smaller than the flexible elongated body.

[0163] The proximal portion 366 need not include a lumen. For example, the proximal portion 366 can be a solid rod, a band or a silk that is connected to the tubular elongated body 360 without a lumen extending therethrough. In the case where the proximal portion 366 is described herein as having a lumen, it should be understood that the proximal portion 366 can also be solid and without a lumen. Compared with the elongated body 360, the proximal portion 366 is usually less flexible, and can be transitioned to even more rigidity toward the most proximal end of the proximal portion 366. Therefore, the catheter propulsion element 300 can have an extremely soft and flexible distal tip that transitions to the proximal rigid proximal portion 366 that is very suitable for twisting and pushing the distal elongated body 360. The flexible transition of the catheter propulsion element 300 and the entire system will be described in more detail below in an example.

[0164] The elongated body 360 can be received within and extend through the interior lumen 223 of the distal lumen portion 222 of the catheter 200 (see Figure 2B ). The elongated body 360 or tubular portion may have an outer diameter. The outer diameter of the tubular portion may have at least one abutment point, at which the difference between the inner diameter of the catheter 200 and the outer diameter of the tubular portion may be no greater than about 0.010", for example, from 0.003" to about 0.010", preferably about 0.006" to about 0.008". As will be described in more detail below, the catheter advancement element 300 may also include a tip portion or distal tip 346 located distal to the at least one abutment point of the tubular portion. The tip portion may have a length and taper along at least a portion of the length. The distal tip 346 of the catheter advancement element 300 may extend beyond the distal end of the catheter 200, such as Figure 2BAs shown. The proximal portion 366 or proximal extension of the catheter advancement element 300 is coupled to and extends proximally from the proximal region of the elongate body 360. The proximal portion 366 may be less flexible than the elongate body 360 and is configured for bi-directional movement of the elongate body 360 of the catheter advancement element 300 within the lumen portion 222 of the catheter 200, and is configured for movement of the catheter system 100 as a whole. The elongate body 360 may be inserted coaxially through the lumen 223 of the lumen portion 222. The outer diameter of at least one region of the elongate body 360 may be sized to substantially fill at least a portion of the inner lumen 223 of the lumen portion 222.

[0165] The total length of the catheter advancement element 300 (e.g., between the proximal end and the most distal tip) may vary, but is typically long enough to extend through the support catheter 200 and beyond the distal end of the support catheter 200 by at least a distance, while at least a length of the proximal portion 366 remains outside the proximal end of the guide sheath 400 and outside the patient's body. In some embodiments, the total length of the catheter advancement element 300 is from about 145 cm to about 150 cm and has a working length from the proximal tab or hub to the most distal tip of from about 140 cm to about 145 cm. When the distal portion of the elongate body 360 extends distally beyond the distal end of the lumen portion 222 to form a mating point or mating region with the catheter, the elongate body 360 may have a length at least as long as the lumen portion 222 of the catheter 200, but the elongate body 360 may be shorter than the lumen portion 222 as long as at least a minimum length remains within the lumen portion 222. In some embodiments, when the distal tip 346 is positioned in its optimal advancement configuration, the minimum length of the elongate body 360 remaining within the lumen portion 222 is at least about 5 cm, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm to about 50 cm. In some embodiments, the axial length of the distal lumen portion 222 may be from about 35 cm to about 75 cm and is shorter than the working length of the guide sheath, and the insertion length of the elongate body 360 may be at least about 45 cm, 46 cm, 47 cm, 48 cm, 48.5 cm, 49 cm, 49.5 cm to about 85 cm.

[0166] The length of the elongate body 360 may allow the distal end of the elongate body 360 to reach a cerebrovascular target within, for example, the M1 or M2 regions, while the proximal region of the elongate body 360 remains at or below the level of a sharp turn along the insertion path. For example, the entry location of the catheter system may be in the femoral artery, and the target embolus may be distal to the right common carotid artery (RCC), such as within the M1 segment of the right middle cerebral artery. As it transitions from the descending aorta (DA), the proximal region of the elongate body 360 (where it transitions to the proximal portion 366) may remain within the blood vessel near highly tortuous anatomical structures (such as the carotid siphon, right common carotid artery (RCC), brachiocephalic trunk (BT), the origin of the brachiocephalic artery from the aortic arch, aortic arch (AA)). This avoids subjecting the insertion of the relatively rigid proximal portion 366 or the material transition between the relatively rigid proximal portion 366 and the elongate body 360 to the sharp turns of the aortic arch or the turns at the origin of the brachiocephalic arteries leading from the aortic arch, which are typically very acute. The length described herein for the distal lumen portion 222 may also apply to the elongate body 360 of the catheter advancement element.

[0167] The length of the proximal portion 366 may also vary. In some embodiments, the proximal portion 366 is from about 90 cm to about 95 cm. The distal portion distal to the distal end of the lumen portion 222 may include a distal tip 346 that projects beyond the length of the distal end of the lumen portion 222 during use of the catheter advancement element 300. As will be described in more detail below, the distal tip 346 of the elongate body 360 is configured to project distally from the distal end of the lumen portion 222 during advancement of the catheter 200 through the tortuous anatomical structures of the cerebrovasculature. The proximal portion 366 that is coupled to and extends proximally from the elongate body 360 may be generally aligned side-by-side with the proximal control element 230 of the catheter 200. During advancement of the catheter 200 through the tortuous anatomical structures to a target location for treatment in a distal blood vessel, the arrangement between the elongate body 360 and the lumen portion 222 may be maintained, and this arrangement helps prevent the distal end of the catheter 200 from getting stuck on a tortuous branch vessel, as will be described in more detail below.

[0168] In some embodiments, the elongate body 360 may have a region of relatively uniform outer diameter extending along at least a portion of its length, and the distal tip 346 tapers from the uniform outer diameter. The outer diameter of the elongate body 360 may include a stepped reduction at a location along its length, for example, a stepped reduction in the outer diameter at the proximal region where the elongate body 360 is coupled to the proximal portion 366. Depending on the inner diameter of the catheter 200, the gap between the catheter 200 and the outer diameter of the elongate body 360 along at least a portion of its length shall not exceed about 0.010", for example, in the range of about 0.003" to 0.010" or between 0.006" and 0.008".

[0169] The elongate body 360 may have an overall shape profile from a proximal end to a distal end that transitions from a first outer diameter having a first length to a tapered outer diameter having a second length. The first length of the first outer diameter region (i.e., the interference fit region between the distal lumen portion 222 and the elongate body 360) may be at least about 5 cm or 10 cm up to about 50 cm. The length of the tapered outer diameter may be between 1 cm and 4 cm. When the catheter advancement element 300 is inserted through the catheter 200, the tapered distal tip 346 is configured to extend beyond and project through the distal end of the lumen portion 222 while a more proximal region of the body 360 (i.e., the first length described above) remains within the lumen portion 222.

[0170] As described above, the distal end of the lumen portion 222 may be blunt and have no change in outer diameter, while the distal tip 346 may be tapered, providing an overall elongate tapered geometry of the catheter system. The outer diameter of the elongate body 360 is also close to the inner diameter of the lumen portion 222 such that the step - up in outer diameter from the elongate body 360 to the lumen portion 222 is minimized. Minimizing the step - up prevents the problem of a lip formed by the distal end of the lumen portion 222 catching on tortuous neurovascular systems (e.g., around the carotid siphon near the ophthalmic artery branch) when the distal tip 346, which is combined with the distal region of the catheter 200, bends and flexes with the vascular anatomy. In some embodiments, the inner diameter of the lumen portion 222 may be at least about 0.052", about 0.054", and the maximum outer diameter of the elongate body 360 may be about 0.048", such that the difference between them is about 0.006". In some embodiments, the inner diameter of the lumen portion 222 may be about 0.070", and the maximum outer diameter of the elongate body 360 may be about 0.062", such that the difference between them is about 0.008". In some embodiments, the inner diameter of the lumen portion 222 may be about 0.088", and the maximum outer diameter of the elongate body 360 may be about 0.080", such that the difference between them is about 0.008". In some embodiments, the inner diameter of the lumen portion 222 may be about 0.072", and the maximum outer diameter of the elongate body 360 is about 0.070", such that the difference between them is only two thousandths of an inch. In other embodiments, the maximum outer diameter of the elongate body 360 is about 0.062", such that the difference between them is about 0.010". Although the outer diameter of the elongate body 360 extends through the lumen of the lumen portion 222, the lumen portion 222 and the elongate body 360 extending coaxially through the lumen portion 222 have sufficient flexibility to navigate tortuous anatomy to reach the level of the M1 or M2 artery without kinking and without damaging the blood vessel.

[0171] The dimensions provided herein are approximate, and each dimension may have engineering tolerances or allowable limits of variation. The use of the term "about" or "approximately" is intended to provide such allowable tolerance for the dimensions involved. Where "about" or "approximately" is not used with a specific dimension herein, the dimension need not be exact.

[0172] The length of the distal tip 346 (e.g., the region of the catheter advancement element 300 configured to extend distally beyond the distal end of the catheter 200 during use to obtain an optimal advancement configuration) can vary. In some embodiments, the length of the distal tip 346 can range between about 0.50 cm to about 4.0 cm from the most distal end of the elongate body 360, or between about 1.0 cm to about 3.0 cm. In other embodiments, the length of the distal tip 346 is between 2.0 cm to about 2.5 cm. In some embodiments, the length of the distal tip 346 varies according to the inner diameter of the catheter 200 to be used with the catheter advancement element 300. For example, for a catheter advancement element 300 sized to be used with a catheter 200 having an inner diameter of about 0.054", the length of the distal tip 346 can be relatively shorter (e.g., 1.2 cm), while for a catheter advancement element 300 sized to be used with a catheter 200 having an inner diameter of about 0.088", the length of the distal tip 346 can be longer (e.g., 2.5 cm). The distal tip 346 can be a constant taper from the outer diameter of the elongate body 360 (e.g., the distal end of the marker 344b) to a second, smaller outer diameter at the most distal end (e.g., the proximal end of the marker 344a), as Figure 7C shown. In some embodiments, over a length of about 1 cm, the constant taper of the distal tip 346 can decrease from an outer diameter of about 0.048" to an outer diameter of about 0.031". In some embodiments, over a length of about 2 cm, the constant taper of the distal tip 346 can decrease from an outer diameter of 0.062" to about 0.031". In additional embodiments, over a length of about 2.5 cm, the constant taper of the distal tip 346 can decrease from an outer diameter of 0.080" to about 0.031". The length of the constant taper of the distal tip 346 can vary, for example, between 0.8 cm to about 2.5 cm, or between 1 cm and 3 cm, or between 2.0 cm and 2.5 cm. The angle of the taper can vary according to the outer diameter of the elongate body 360. For example, the taper can be between 0.9 degrees and 1.6 degrees relative to the horizontal plane. The taper can be at an angle of 2 - 3 degrees with respect to the centerline of the elongate body 360.

[0173] The catheter advancement element 300 may include a distal tip 346 that tapers over a length. The elongate body 360 of the catheter advancement element 300 may have an inner diameter that does not vary along its length even as the distal tip 346 tapers. Accordingly, the inner diameter of the lumen extending through the tubular portion of the catheter advancement element 300 may remain uniform, and the wall thickness of the distal tip 346 may be reduced to provide a tapered portion. The wall thickness may thin distally along the length of the tapered portion. Thus, the material properties, in combination with the wall thickness, angle, and length of the tapered portion, may all contribute to the overall maximum flexibility of the distal most end of the distal tip 346. The catheter advancement element 300 undergoes a transition in flexibility from the distal most end toward a point of engagement where the outer diameter achieved is no more than about 0.010” different from the inner diameter of the catheter 200.

[0174] Due to material properties rather than changes in external dimensions, the distal tip 346 need not be tapered and can achieve its soft, atraumatic, and flexible characteristics, thus facilitating intravascular navigation to emboli in tortuous anatomy. Additionally or alternatively, the distal tip 346 of the elongate body 360 can have a flexible transition along its length. The most flexible region of the distal tip 346 can be its distal end. Move proximally from the distal end towards the proximal region of the distal tip 346 along its length. For example, the distal tip 346 can be formed of a material having a material hardness of no greater than 35D or approximately 62A and transitions proximally to a position formed of a material having a material hardness of no greater than 55D and 72D until the proximal portion 366 is less flexible, which can be a stainless steel hypotube, or a combination of material properties and a tapered shape. The material for the region forming the elongate body 360 can include a PEBAX (e.g., PEBAX 25D, 35D, 55D, 72D) with a lubricity additive compound such as Mobilize (Compounding Solutions of Lewiston, Maine). In some embodiments, the material for the region forming the elongate body 360 can be tetrahydrofuran 62A. Incorporating the lubricity additive directly into the polymeric elongate body means that there is no need to incorporate a separate lubricity liner, such as a polytetrafluoroethylene liner. This allows for a more flexible element that can navigate the distal cerebral anatomy and is not prone to kinking. Similar materials can be used to form the distal lumen portion 222 of the catheter 200, thus providing similar advantages. The flexibility of the distal tip 346 can be achieved through a combination of a flexible lubricious material and a tapered shape. For example, the length of the tip 346 can be kept shorter than 2 cm - 3 cm, but maintain optimal deliverability due to the change in the flexible material from the farthest distal tip to a more proximal region away from the farthest distal tip. In one embodiment, the elongate body 360 is formed of silicone embedded with PEBAX (polyether block amide), which is designed to maintain the highest degree of flexibility. The wall thickness of the distal end of the lumen portion 222 can also be made thin enough such that the lip formed by the distal end of the lumen portion 222 relative to the elongate body 360 is minimized.

[0175] The advantage of the elongate body 360 over the microcatheter is that it can have a relatively large outer diameter that is only 0.003” - 0.010” smaller than the inner diameter of the distal lumen portion 222 of the catheter 200 and still maintain a high degree of flexibility for navigating tortuous anatomy. When the gap between the two components is too tight (e.g., less than about 0.003”), the force required to slide the catheter advancement element 300 relative to the catheter 200 may damage one or both of the two components and increase the risk to the patient during the procedure. This gap results in an over-tight fit and does not provide optimal relative sliding. When the gap between the two components is too loose (e.g., greater than about 0.010”), a lip forms at the distal end of the catheter 200 that can easily catch on branch vessels when advancing through the tortuous neurovascular system (e.g., around the carotid siphon from which the ophthalmic artery branches).

[0176] The ID / OD gap between the elongate body 360 and the distal lumen portion 222 can be within this size range (e.g., 0.003” – 0.010”) along most of its length. For example, the elongate body 360 can have a relatively uniform outer diameter that is between about 0.048” and about 0.080” from the proximal region to the distal region up to the point where the taper of the distal tip 346 begins. Similarly, the distal lumen portion 222 of the catheter 200 can have a relatively uniform inner diameter that is between about 0.054” and about 0.088” from the proximal region to the distal region. Thus, the difference between their respective inner and outer diameters along most of their length can be within the gap size range of 0.003” to 0.010”. The distal tip 346 of the tapered elongate body 360 will have a larger gap size relative to the inner diameter of the distal lumen portion 222. However, during use, this tapered distal tip 346 is configured to extend distally beyond the distal end of the catheter 200 such that the region of the elongate body 360 having an outer diameter sized to match the inner diameter of the distal lumen portion 222 is positioned within the lumen of the catheter 200, thereby minimizing the lip at the distal end of the catheter 200.

[0177] The elongated body 360 may be formed of various materials that provide suitable flexibility and lubricity. Exemplary materials include high density polyethylene, 72D PEBAX, 90D PEBAX or equivalent rigid and lubricious materials. At least a portion of the elongated body 360 may be enhanced to improve navigation and torsion (e.g., braided reinforcement layer). The flexibility of the elongated body 360 may increase toward the distal tip 346, so that the distal region of the elongated body 360 is softer, more flexible and easier to articulate and bend than the proximal region. For example, the more proximal region of the elongated body may have a bending stiffness that is flexible enough to navigate tortuous anatomical structures such as the carotid siphon without kinking. If the elongated body 360 has a braided reinforcement layer along at least a portion of its length, the braided reinforcement layer may terminate at a distance proximal to the distal tip 346. For example, the distance from the braided end to the distal tip may be about 10 cm to about 15 cm or about 4 cm to about 10 cm or about 4 cm to about 15 cm.

[0178] In some embodiments, the elongated body 360 can be generally tubular along at least a portion of its length such that it has a single lumen 368 extending parallel to the longitudinal axis of the catheter advancement element 300 (see Figures 7A - 7C as well as Figures 10A - 10C In one embodiment, the single lumen 368 of the elongated body 360 is sized to accommodate a guidewire, but the use of the catheter advancement element 300 generally does not require a guidewire. Methods of using the catheter advancement element 300 to deliver a catheter to a distal region of the brain without a guidewire are described in more detail below.

[0179] A guidewire may extend generally concentrically from the proximal opening through a single lumen 368 to a distal opening, and the guidewire may extend through the distal opening. In some embodiments, the proximal opening is at the proximal end of the catheter advancement element 300, such that the catheter advancement element 300 is configured for an over-the-air (OTW) approach. In other embodiments, the proximal opening is a quick-change opening 362 through the wall of the catheter advancement element 300, such that the catheter advancement element 300 is configured for quick replacement, rather than OTW or in addition to OTW. In this embodiment, the proximal opening 362 extends through the side wall of the elongated body and is positioned a distance from the proximal tab 364 and distal to the proximal portion 366 (see Figures 7A - 7B 7D). The proximal opening 362 can be positioned about 10 cm from the distal tip 346, up to about 20 cm from the distal tip 346. In some embodiments, the proximal opening 362 can be positioned near the area where the elongated body 360 joins the proximal portion 366, for example, just distal to one end of the hypotube (see Figure 7B In other embodiments, the proximal opening 362 is located more distally, for example, about 10 cm to about 18 cm from the distal end of the elongated body 360 (seeFigure 7D )。The proximal opening 362 positioned closer to the distal tip 346 allows for easier removal of the catheter advancement element 300 from the catheter 200, leaving the guide wire in place for "quick exchange" type procedures. The quick exchange can be performed by only one person. The catheter advancement element 300 can be easily replaced with another device using the same guide wire held in place. The single lumen 368 of the elongate body 360 can be configured to receive a guide wire having a diameter in the range between 0.014" and 0.018" or between 0.014" and 0.022". In this embodiment, the inner diameter of the lumen of the elongate body 360 can be between 0.020" and 0.024". The guide wire, the catheter advancement element 300, and the catheter 200 can all be coaxially assembled and inserted through the working lumen of the guide sheath 400. The inner diameter of the lumen 368 of the elongate body 360 can be from 0.019" to about 0.021".

[0180] Figure 7D Another embodiment of the catheter advancement element 300 configured for quick exchange is shown. The quick exchange configuration can significantly shorten the device length, reduce staffing, and reduce fluoroscopy. As with other embodiments described herein, the catheter advancement element 300 can include an inextensible flexible elongate body 360 coupled to a proximal portion 366, the proximal portion 366 being coupled to a proximal tab 364 or hub 375. The region near the distal tip 346 can be tapered such that the outer diameter tapers over a length of about 1 cm to 4 cm. In some embodiments, the distal taper length is 2.5 cm. In some embodiments, the distal tip 346 tapers from about 0.080" to about 0.031". Moreover, the distal tip 346 can be formed of a material having a material hardness (such as 62A and 35D), which transitions in the proximal direction until the proximal portion 366 to a material with an increasing hardness (such as 55D and 72D). For example, Figure 7D A section 371 of the elongate body 360 is shown, which includes a distal tip 346 formed of a material having a material hardness of 35D and a length of about 10 cm to about 12.5 cm. The section 371 of the elongate body 360 includes a distal tip 346 formed of a material having a material hardness of 62A and a length of about 10 cm to about 12.5 cm. The section 372 of the elongate body 360 is formed of a material having a material hardness of 55D and has a length of about 5 cm to about 8 cm. The length of the section 373 of the elongate body 360 formed of a material having a material hardness of 72D can be about 25 cm to about 35 cm. The combined three sections 371, 372, 373 can form the insertion length of the elongate body 360, from which the proximal portion 366 is coupled to the end of the elongate body 360 to the distal tip 346, and this insertion length can be about 49 cm.

[0181] Figures 10A - 10C One embodiment of a catheter advancement element 300 incorporating a reinforcement layer 380 is shown. The reinforcement layer 380 can be a braid or other type of reinforcement to improve the torquability of the catheter advancement element 300 and to help bridge components of the catheter advancement element 300 that have these differences in flexibility. The reinforcement layer 380 can bridge the transition from the rigid proximal portion 366 to the flexible elongated body 360. In some embodiments, the reinforcement layer 380 can be a braid located between the inner and outer layers of Pebax 382, ​​384 (see Figure 10C ). The reinforcement layer 380 may terminate a certain distance proximal to the distal tip portion 346. Figure 10A An elongated body 360 is shown having a segment 371 and a segment 373 located proximal to the segment 371. The segment 371 may include a distal tip 346 formed of a material having a material hardness of at most about 35D. The segment 371 is an unreinforced polymer having a length of about 4 cm to about 12.5 cm. The segment 373 of the elongated body 360 located proximal to the segment 371 may include a reinforcement layer 380 and may extend a total of about 37 cm to the unreinforced distal segment 371. The proximal region of the reinforcement layer 380 may overlap with the distal region of the proximal portion 366, so that a small overlap of the hypotube and reinforcement exists near the transition between the proximal portion 366 and the elongated body 360.

[0182] Again targeting Figure 7D , an entry port 362 for an operative guidewire may be positioned a distance from the most distal end of the elongated body 360. In some embodiments, the entry / exit port 362 may be about 18 cm from the most distal end, thereby forming a quick-change wire entry / exit segment 370. The outer diameter of the elongated body 360 (segments 371 and 372) within segment 370 may be about 0.080"-0.082", while the segment 373 on the proximal side of the quick-change wire entry / exit segment 370 may have a stepped-down outer diameter, for example, about 0.062"-0.064".

[0183] The tubular portion of the catheter advancement element may have an outer diameter having at least one abutment point. The difference between the outer diameter at the abutment point and the inner diameter of the lumen at the distal end of the distal catheter portion may be no greater than about 0.010". The at least one abutment point of the tubular portion may be a point along the length of the tubular portion. The at least one abutment point of the tubular portion may have a length of at least about 5 cm to about 50 cm, including, for example, at least about 6 cm, at least about 7 cm, at least about 8 cm, at least about 9 cm, at least about 10 cm, at least about 11 cm, or at least about 12 cm up to about 50 cm. The length does not have to be uniform, such that the length does not have to be just snug along its entire length. For example, the abutment point area may include ridges, grooves, slits, or other surface features.

[0184] In other embodiments, the entire catheter advancement element 300 can be a tubular element configured to receive a guidewire through both the proximal portion 366 and the elongate body 360. For example, the proximal portion 366 can be a hypotube or tubular element having a lumen in communication with a lumen 368 extending through the elongate body 360 ( Figure 3 as shown). In some embodiments, the proximal portion 366 can be a tapered hypotube of stainless steel coated with PTFE having an outer diameter of 0.026”. In other embodiments, the outer diameter can be between 0.024” and 0.030”. In some embodiments, such as in an over-the-wire configuration, the proximal portion 366 can be a tapered hypotube coupled to the proximal hub 375. The proximal portion 366 can extend eccentrically or concentrically with the distal lumen portion 222. As Figure 7E best shown, the proximal portion 366 can be a stainless steel hypotube. The proximal portion 366 can be a solid wire having a circular or oval cross-sectional shape. The proximal portion 366 can be a flat ribbon having a rectangular cross-sectional shape. The ribbon can be bent into a circular, oval, C-shaped, or quarter-circle, or other cross-sectional shape along an arc. Whether or not a lumen extends therethrough, the proximal portion 366 can have any of a variety of cross-sectional shapes, including circular, oval, C-shaped, D-shaped, or other shapes. In some embodiments, the proximal portion 366 is a hypotube having a D-shape such that the inward-facing side is flat and the outward-facing side is circular. The circular side of the proximal portion 366 can be shaped to engage the corresponding circular inner surface of the sheath 400. The hypotube can have a lubricious coating, such as PTFE. The hypotube can have an inner diameter of approximately 0.021”, an outer diameter of approximately 0.0275”, and a total length of approximately 94 cm, thereby providing a working length of approximately 143 cm for the catheter advancement element 300. Including the proximal hub 375, the catheter advancement element 300 can have a total length of approximately 149 cm. In some embodiments, the hypotube can be a tapered section having a length of approximately 100 mm starting at 0.3 mm thick proximally and ending at a thickness of 0.10 mm to 0.15 mm. In additional embodiments, the elongate body 360 can be a solid element coupled to the proximal portion 366 that does not have a guidewire lumen.

[0185] The proximal portion 366 is shown in Figure 2A 、 7A -7D and 10A as having an outer diameter smaller than the outer diameter of the elongate body 360. The outer diameter of the proximal portion 366 need not decrease in a stepped fashion and can also have the same outer diameter as the elongate body 360. For example, the proximal portion 366 can incorporate a hypotube or other reinforcing element coated with one or more polymers such that the proximal portion 366 has substantially the same outer diameter as the elongate body 360.

[0186] As Figures 7F - 7JAs best shown, the proximal end of the proximal portion 366 can be coupled to the proximal hub 375. The proximal hub 375 can be a overmolded component having a Luer threaded portion 377 and a Luer taper portion 378 formed on the inner side of the proximal hub 375. The proximal hub 375 can incorporate tabs 364 to make it easier for the user to grasp. The proximal hub 375 prevents the catheter advancement element 300 and the catheter 200 from advancing beyond the distal tip of the base sheath 400 or the guiding catheter by restricting insertion into the proximal RHV 434, thus providing critical functional and safety features for the normal operation of the system 10.

[0187] At least a portion of the solid elongate body 360 (such as the distal tip 346) can be formed of, or embedded with, or attached to a malleable material that tapers down to a smaller size at the distal end. The distal tip 346 can be shaped at a desired angle or shape, similar to the way a guide wire can be used. The malleable length of the elongate body 360 can be at least about 1 cm, 3 cm, 5 cm, up to about 10 cm, 15 cm or more. In some embodiments, the malleable length can be about 1%, 2%, 5%, 10%, 20%, 25%, 50% or more of the total length of the elongate body 360. In some embodiments, the catheter advancement element 300 can have an operating length of about 140 cm to about 143 cm, and the elongate body 360 can have an insertion length of about 49 cm. The insertion length can be the PEBAX portion of the elongate body 360, which is about 49.5 cm. Thus, the malleable length of the elongate body 360 can be between about 0.5 cm to about 25 cm or greater. The shape change can be determined by the user manually shaping the malleable length prior to insertion, or the tip can be pre-shaped at a specific angle or curve during manufacturing. Alternatively, the shape change can be a reversible and actuatable shape change such that the tip forms a shape when activated by the user, allowing the tip to be used in a straight form until the user desires a shape change. The catheter advancement element 300 can also include a shaping mandrel extending through the lumen of the elongate body 360 such that the physician can mold the distal tip 346 into a desired shape during use. Thus, the moldable distal tip 346 can be incorporated onto the elongate body 360 having a guide wire lumen.

[0188] The elongate body 360 can extend along the entire length of the catheter 200, including the distal lumen portion 222 and the proximal control element 230, or the elongate body 360 can incorporate a proximal portion 366 that is generally aligned side by side with the proximal control element 230 of the catheter 200. The proximal portion 366 of the elongate body 360 can be positioned coaxial or eccentric with the elongate body 360. The proximal portion 366 of the elongate body 360 can have a lumen extending therethrough. Alternatively, the portion 366 can be a solid rod or strip without a lumen.

[0189] Again with respect to Figures 7A - 7D , similar to the distal lumen portion 222 of the catheter 200, the elongate body 360 may have one or more radiopaque markers 344 along its length. The one or more markers 344 may vary in size, shape, and position. One or more markers 344 may be coupled to one or more portions of the catheter advancement element 300, such as tip-to-tip markers, tip-to-taper markers, RHV proximity markers, fluoroscopic shield markers, or other markers, to provide various information about the relative positions of the catheter advancement element 300 and its components. In some embodiments, as best shown in Figure 7C , the distal region may have a first radiopaque marker 344a, and a second radiopaque marker 344b may be positioned to indicate the boundary between the tapered portion of the distal tip 346 and a more proximal region of the elongate body 360 having a uniform or maximum outer diameter. This provides the user with information about the optimal extension of the distal tip 346 relative to the distal end of the lumen portion 222 such that the lip at this distal end of the lumen portion 222 is minimized for advancing through tortuous anatomy. In other embodiments, such as where the distal tip 346 is not necessarily tapered but has an overall flexural variation along its length, the second radiopaque marker 344b may be positioned to indicate the region where the relative flexure of the elongate body 360 (or the distal tip 346 of the elongate body 360) and the distal end of the lumen portion 222 is substantially the same. The marker material may be a platinum / iridium band, tungsten, platinum, or tantalum-impregnated polymer, or other radiopaque markers that do not affect the flexibility of the distal tip 346 and the elongate body 360. In some embodiments, the radiopaque marker is an extruded PEBAX loaded with tungsten to achieve radiopacity. In some embodiments, the proximal marker band may be approximately 2.0 mm wide, and the distal marker band may be approximately 2.5 mm wide to provide distinguishable information about the distal tip 346.

[0190] The proximal control element 230 of the catheter 200 may include a proximal protrusion 234 on the proximal end of the proximal control element 230. Similarly, the proximal portion 366 of the elongate body 360 may include a tab 364. The tabs 234, 364 may be configured to be removably and adjustably connected to each other and / or to their corresponding proximal portions. This connection allows the catheter advancement element 300 to be reversibly coupled to the catheter 200 to lock (and unlock) the relative extension of the distal lumen portion 222 and the elongate body 360. This allows the catheter 200 and the catheter advancement element 300 to be advanced as a unit. In the locked configuration, the tab 364 or the proximal portion 366 may engage the catheter tab 234. In the unlocked configuration, the tab 364 may disengage from the catheter tab 234. The tab 364 or the proximal portion 366 may be attached (e.g., snapped or locked) into the catheter tab 234, thereby maintaining the relationship of the corresponding portions of the elongate body 360 and the catheter 200 in the locked configuration. The tab 364 may be a part of the proximal hub 375, such as Figures 7F - 7J the hub 375 shown.

[0191] This locking may be achieved, for example, by using a brake on the tab 364 that snaps into place within a recess formed in the catheter tab 234 and vice versa. For example, the tab 234 of the catheter 200 may form a ring having a central opening extending therethrough. The tab 364 of the body 360 may have an annular brake having a central post sized to be inserted through the central opening of the tab 234 such that the ring of the tab 234 is received within the annular brake of the tab 364, thereby forming a single gripping element to facilitate advancement and / or retraction of the catheter system through the access sheath by the user. The tabs 234, 364 may be fixed or slidable to accommodate different relative positions between the elongate body 360 and the lumen portion 222 of the catheter 200. In some embodiments, the proximal end of the proximal control element 230 of the catheter 200 may include a coupling part 334, such as configured to receive the proximal portion 366 of the catheter advancement element 300 (see Figure 2A) clips, clamps, C-shaped elements, or other connectors. The coupling part 334 may be configured to snap together with the proximal portion 366 by an interference fit, such that a first level of force is required to insert the proximal portion 366 into the clip of the tab 234, and a second, higher level of force is required to remove the proximal portion 366 from the clip of the tab 234. However, after the proximal portion 366 is inserted into the coupling part 334, the catheter advancement element 300 and the catheter 200 may still be slidably adjustable relative to each other along the longitudinal axis of the system. The amount of force required to slidably adjust the relative positions of the two components may be such that inadvertent adjustment is avoided and the relative position can be maintained during use, but adjustment can be made when deliberately modified. The configuration of the connection between the proximal portion 366 of the catheter advancement element 300 and the proximal control element 230 of the catheter 200 may vary. However, generally, the connection is configured to be reversible and adjustable while still providing sufficient holding force between the two elements in a relatively user-friendly manner (e.g., allowing single-handed use) and managing the proximal ends of the components (e.g., preventing the proximal control element 230 and the proximal portion 366 from twisting and tangling with each other). The coupling part 334 configured to prevent tangling and assist in the management of the proximal portion may be integrated with the tab or may be a separate part located along its proximal region.

[0192] The catheter advancement element 300 may be placed in a locked configuration with the catheter 200, which is configured to improve tracking through tortuous and often diseased vasculature in acute ischemic stroke. Other configurations are contemplated herein. For example, the elongate body 360 may include one or more brakes on its outer surface. The brakes may be located near the proximal region and / or the distal region of the elongate body 360. The brakes are configured to lock with corresponding shaped surface parts on the inner surface of the lumen portion 222 through which the elongate body 360 extends. The catheter advancement element 300 and the catheter 200 may incorporate more than one locking connection point between them. For example, the coupling part 334 (e.g., a clip, clamp, C-shaped element, or other connector) is configured to hold together the proximal control element 230 or the tab 234 of the catheter advancement element 300 and the catheter 200.

[0193] In some embodiments, the proximal control element 230 of the catheter 200 may extend beside or inside a dedicated channel of the proximal portion 366. The channel may be located along the length of the proximal portion 366 and have a cross-sectional shape that matches the cross-sectional shape of the catheter proximal control element 230, such that the proximal control element 230 of the catheter 200 can be received within the channel and slide smoothly bidirectionally along the channel. Once the catheter 200 and the elongate body 360 are fixed, the combined system (i.e., the catheter 200 - catheter advancement element 300) may be delivered to the target site, for example, through the working lumen of the guide sheath 400 described elsewhere herein.

[0194] The catheter advancement element 300 (with or without an incorporated reinforcement layer) loaded within the lumen of catheter 200 can be used to advance catheter 200 into the distal regions of the brain (e.g., the level of the MCA). The traditional approach for the Circle of Willis uses a triaxial system that includes a guidewire placed within a conventional microcatheter, which is placed within an intermediate catheter. The entire coaxial system can be extended through a base catheter or sheath. The sheath is typically positioned such that the distal tip of the sheath is placed within the high carotid artery. The coaxial system is typically advanced consistently near the end of the carotid artery, and then the conventional coaxial system must be advanced in a stepwise manner in a separate pass. This is due to two consecutive 180-degree or greater turns (see Figures 1A - 1C ). The first 180-degree turn is at the level of the petrous to cavernous internal carotid artery. The second 180-degree turn is at the end of the cavernous carotid artery when it passes through the bony element and reaches the branches entering the anterior cerebral artery (ACA) and middle cerebral artery (MCA). This S-shaped region is referred to herein as the "siphon" or "carotid siphon". The ophthalmic artery originates from the cerebral ICA, which represents the common point where the catheter hangs when entering the anterior circulation.

[0195] The conventional microcatheter system can be advanced into the anterior circulation via a guidewire. The inner diameter of the conventional microcatheter is significantly larger than the outer diameter of the guidewire over which it is advanced, thereby forming a lip at the distal region of the system that can get caught on these side branches when passing through the siphon. The conventional microcatheter system (i.e., guidewire, microcatheter, and intermediate catheter) is advanced through the curves of the carotid siphon sequentially to the distal target site rather than passing through smoothly in one go. The curves of the carotid siphon are performed one by one with a stepwise advancement technique. For example, to pass through the carotid siphon, the conventional microcatheter is held stationary while the guidewire is advanced alone for a first distance (i.e., through the first turn of the siphon). Then, the guidewire is held stationary while the conventional microcatheter is advanced alone over the guidewire through the first turn. Then, the conventional microcatheter and guidewire are held stationary while the intermediate catheter is advanced alone over the microcatheter and guidewire through the first turn. The process is repeated to pass through the second turn of the siphon, which is generally considered the more challenging turn for entering the cerebral blood vessels. The microcatheter and intermediate catheter are held stationary while the guidewire is advanced alone for a second distance (i.e., through the second turn of the siphon). Then, the guidewire and the intervening catheter are held stationary while the microcatheter is advanced alone over the guidewire through the second turn. Then, the wire and microcatheter are held stationary while the intervening catheter is advanced alone through the second turn. This multi-stage stepwise operation is a time-consuming process that requires multiple handovers of components by multiple people. For example, two hands hold the components in place and push them over each other, forcing the user to perform preparatory steps. The need for a stepwise operation is because the stepped transition between these components (e.g., guidewire, microcatheter, and intermediate catheter) makes advancement overly challenging.

[0196] In contrast, the catheter 200 and the catheter advancement element 300 eliminate this multi-stage, stepwise component advancement process through the siphon into the distal site. The catheter 200 and the catheter advancement element 300 can be advanced as a single unit through the two turns of the carotid siphon CS. Both turns can be smoothly traversed or pushed through in a single pass to reach the target in the cerebral vasculature without the need to gradually adjust their relative extension or rely on conventional stepwise advancement techniques using conventional microcatheters. The catheter advancement element 300 passing through the catheter 200 through which it extends allows the user to consistently advance them from the first bend of the siphon to the second bend in the same relative position, past the end of the cavernous carotid artery and into the ACA and MCA. Importantly, the advancement of both components can be achieved in a single smooth movement through the two bends without any change in the position of the hand.

[0197] The catheter advancement element 300 can be juxtaposed relative to the catheter 200 to provide an optimal relative extension between the two components for a single smooth advancement. The catheter advancement element 300 can be positioned to pass through the lumen of the catheter 200 such that its distal tip 346 extends beyond the distal end of the catheter 200. The distal tip 346 of the catheter advancement element 300 eliminates the stepped transition between the inner member and the outer catheter 200, thus avoiding problems of getting stuck on the branch vessels in the region of the vasculature and allowing the catheter 200 to easily traverse the multiple angled turns of the carotid siphon CS. The optimal relative extension can be, for example, that the distal tip 346 of the elongate body 360 extends distally beyond the distal end of the catheter 200. The length by which the distal tip 346 extends distally beyond the distal end of the catheter 200 during advancement can be between 0.5 cm and about 4 cm. This juxtaposition can be a locking engagement with a mechanical element or a locking engagement simply by the user holding the two components together.

[0198] The components can be advanced over a pre-positioned guidewire or without any guidewire at all. In some embodiments, the guidewire can be pre-assembled with the catheter advancement element 300 and the catheter 200 such that the guidewire extends through the lumen of the catheter advancement element 300 and is all loaded through the lumen of the catheter 200 before insertion into the patient. The pre-assembled components can be simultaneously inserted into the sheath 400 and advanced together through and past the turns of the carotid siphon.

[0199] The optimal relative extension of the catheter 200 and the catheter advancement element 300 can additionally be based on the staggering of material transitions. Figure 11is a schematic diagram showing the approximate location of material transitions in the catheter advancement element 300 and the approximate location of material transitions in the catheter 200. For example, the catheter advancement element 300 may include a proximal portion 366, which may be a hypotube, having a material hardness of approximately 72D. The proximal portion 366 transitions to a region having a material hardness of approximately 55D at location 1101a, transitions to a region having a material hardness of approximately 35D at location 1101b, and transitions to a region having a material hardness of approximately 35D at location 1101c. Similarly, the catheter 200 may include a proximal control element 230, which is a stainless steel band. The proximal control element 230 transitions to a region having a material hardness of 72D at position 1103a, transitions to a region having a material hardness of 55D at position 1103b, transitions to a region having a material hardness of about 40D at position 1103c, transitions to a region having a material hardness of about 35D at position 1103d, transitions to a region having a material hardness of 25D at position 1103e, transitions to a region having a material hardness of about 85A at position 1103f, and transitions to a region having a material hardness of about 80A at position 1103g. The distal-most region of the catheter advancement element 300 may be formed of tetrahydrofuran having a material hardness of about 62A. Position 1101 of the catheter advancement element 300 and position 1103 of the catheter 200 may be staggered such that these positions are offset from each other. There may be more or fewer material transitions within the catheter advancement element and the catheter.

[0200] The catheter 200 and the catheter push element 300 can be preassembled during manufacture so that the optimal length of the catheter push element 300 extends to the distal extension and / or material transition staggered to the distal end of the catheter 200. The optimal extension length can be such that the entire length of the tapered distal tip of the catheter push element 300 extends beyond the distal end of the catheter 200, so that the outer diameter of the catheter push element 300 positioned with at least one fitting point is substantially aligned with the distal end of the catheter 200. This can substantially align the outer diameter area of ​​the elongated body 360 that fits with the distal end of the catheter 200, so that it remains in the lumen of the catheter 200 and only the tapered area of ​​the distal tip 346 extends to the distal side of the lumen of the catheter 200. This relative arrangement provides an optimal arrangement for advancement through tortuous blood vessels, in which the lip at the distal end of the system will constitute the greatest difficulty. This optimal preassembled arrangement can be maintained by a coupler configured to engage both the proximal control element 230 of the catheter 200 and the proximal portion 366 of the catheter push element 300. The coupling can be used during surgery. Alternatively, the coupling can be removed before surgery.

[0201] Different regions of the distal lumen 222 and the elongated body 360 of the catheter advancement element 300 may have different bending stiffnesses. Bending stiffness (in N-mm2 ) It can be measured by evaluating the force (in Newtons (N)) generated after deflecting the device by a certain distance using a specific gauge length. Figure 12 It is a schematic diagram of a test system 1205 for evaluating the flexural stiffness or flexural force of the various components described herein. The test system 1205 can vary as known in the art. Figure 12 The illustrated test system includes a pin 1210 that forms a fixed point, and an anvil 1215 that is connected to a strain gauge 1220 forming a measurement point through a rod 1222. The pin 1210 can hold a sample 1201 to be tested such that the gauge length 1225 of the sample 1201 is exposed. The anvil 1215 is attached to the strain gauge 1220 through the rod 1222 and can be urged against a portion of the sample 1201 that is positioned at the gauge length 1225 away from the pin 1210. The anvil 1215 can displace this portion such that this portion triggers a force measurable by the strain gauge 1220. The gauge length 1225 can be about 5 mm. The anvil 1215 can have a width of, for example, about 2 mm, such that the minimum gauge length is about 3 mm. This length may vary depending on the test system.

[0202] The flexural stiffness (modulus of elasticity x moment of inertia of the area) can be calculated according to the equation EI = FL 3 / 3δ, where F is the deflection force, L is the gauge length, and δ is the deviation. For example, using a gauge length of 3 mm (L = 3 mm) and deflecting the tip of the catheter by 2 mm (δ = 2 mm), a force of 0.05 - 0.5 N can be generated. In some embodiments, the flexural stiffness at the most distal end of the distal lumen portion can be in the range between 0.225 - 2.25 N-mm 2 As a comparison, the flexibility of the catheter advancement element 300 based on similar deflection measurements and calculations can be as follows. At a deviation of 2 mm and a force gauge length of 3 mm, the flexural force at the distal tip of the catheter advancement element 300 can be in the range between 0.005 - 0.05 N, or the flexural stiffness can be in the range between 0.0225 - 0.225 N-mm 2 between the ranges. Other operational catheters described herein can have a similar flexibility range, thereby providing a variable relative stiffness from the proximal end to the distal end of the catheter, as described elsewhere herein.

[0203] Figures 13A - 13B Schematically shows points along the catheter system that can be utilized Figure 12Tested using the test system shown. These points may vary depending on the overall dimensions of the catheter system. The various points of the catheter system 150 can be tested when the catheter system 150 is placed in the advancement configuration. The catheter 200 can have a lumen and a distal end with an opening starting from the lumen 223. The inner diameter of the lumen at the distal end can be at least about 0.052". The tubular portion 360 of the catheter advancement element 300 can have an outer diameter with at least one mating point, where the difference between the inner diameter and the outer diameter at the mating point is no greater than about 0.010". The at least one mating point can be a point on the catheter advancement element 300 that is exactly proximal to the tapered distal tip 346. When the catheter advancement element 300 is in the advancement configuration and coaxially positioned within the distal lumen portion 222 of the catheter 200, at least one mating point of the tubular portion 360 can be substantially aligned with the distal end of the catheter 200. When in this configuration, the distal tip portion 346 of the catheter advancement element 300 extends distally beyond the distal end of the catheter 200. In some embodiments, the difference at the mating point is no greater than about 0.010" or between about 0.006" and 0.008".

[0204] The tubular portion 360 of the catheter advancement element 300 can have a radiopaque marker band that is embedded within or located on the wall of the tubular portion 360 near the distal region. A first radiopaque marker band 344a can be located at the distal end of the tapered tip portion 346, and a second radiopaque marker band 344b can be located at the proximal end of the tapered tip portion 346. The proximal radiopaque marker band 344b can have a proximal edge, a distal edge, and a width between the proximal edge and the distal edge. When in the advancement configuration, the proximal edge of the radiopaque marker band 344b can be substantially aligned with the distal end of the distal catheter portion 222 such that the radiopaque marker band 344b remains outside the lumen 223 of the distal catheter portion 222. At least a portion of the radiopaque marker band 344b can be located at the mating point or at a point where the outer diameter of the catheter advancement element 300 is no greater than 0.010", preferably about 0.006" and 0.008" smaller than the inner diameter of the catheter 200 within which it is located. At least one mating point of the tubular portion 360 can be located proximal to the tip portion 346 and can be the location where the tapered portion of the tip portion 346 substantially terminates. This allows the tapered tip portion 346 to extend completely beyond the distal end of the catheter 200, and the mating point to be substantially aligned within the distal opening of the lumen 223 of the distal catheter portion 222, thereby minimizing the distal-facing lip that may be formed by the catheter 200. The mating point can be located along at least a portion of the length of the outer diameter of the tubular portion 360, which has a length of at least about 5 cm to about 10 cm and is substantially uniform or non-uniform.

[0205] The tip portion 346 can include at least three points spaced along the length of the tip portion (e.g., seeFigures 13A - 13B Of P1, P2, P3). The distal point P1 of at least three points can be positioned proximally a certain distance from the most distal end of the catheter advancement element 300. This distance can be the minimum distance required for the test system to generate a gauge length, such as at least about 3 mm to about 5 mm. The middle point P2 of at least three points can be positioned proximally a certain distance from the distal point P1. The proximal point P3 of at least these points can be positioned proximally a certain distance from the middle point P2. Additional points can be measured on the tapered tip 346, and these additional points are provided as examples.

[0206] Figure 13A Points that can be generally tested on the system 150 are also shown. The coaxial catheter system 150 in the advancement configuration can include at least two system points along the length of the coaxial system 150. The first system point S1 of at least two system points can be located proximally to the distal end of the catheter 200. The first system point S1 generally takes into account the combined bending force of the catheter 200 and the bending force of the catheter advancement element 300 extending through the catheter 200 (see Figure 13B the dashed line in). The first system point S1 can be located proximally to the distal end of the catheter 200 with a gauge length of about 5 mm. The second system point S2 of at least two system points can be located distally to the first system point S1 with a distance of at least about 1 mm distally from the distal end of the catheter portion, for example. The second system point S2 can take into account the bending force of the catheter advancement element 300 extending outside the catheter 200. The second system point S2 is Figure 13A shown in as a point different from P3, but the second system point S2 can be the same as the proximal portion P3 or can be the same as other points (such as P4). These points are provided for illustrative purposes and are not intended to be limiting. Other points are considered herein.

[0207] Figure 13B The theoretical bending forces (N) of the catheter system 150 at various points along the length of the system 150 are shown. At least three points on the tip 346 include P1, P2, P3, and P4 spaced along the length of the tip 346 of the catheter advancement element 300 (represented by the dotted line). When in the advancement configuration, each of these points can be located distally to the distal end of the catheter 200 (solid line), and thus, only the bending force of the catheter advancement element 300 is considered. Figure 13B A fifth point P5 along the length of the catheter advancement element 300 is also shown in, and when the system 150 is in the advancement configuration, P5 can be located at a position inside the catheter 200. However, P5 is only considered for measuring the bending force of the catheter advancement element 300.

[0208] Both the catheter 200 and the catheter advancement element 300 can have any one of a variety of material transitions from the distal end towards the proximal end, such that when the catheter advancement element 300 is coaxially positioned within the catheter 200 in the advancement configuration, the flexibility of the system 150 linearly transitions from the flexibility of the distal tip of the catheter advancement element 300 towards the more proximal regions of the system 150. In other words, the transition from the flexibility of the distal tip 346 of the catheter advancement element 300 (which, when in the advancement configuration, is outside the distal end of the catheter 200) to the flexibility of the system 150 as a whole (i.e., the catheter advancement element 300 plus the catheter 200) can be defined by a slope that does not include a distinct step increase and is substantially constant.

[0209] Figure 13B This additional stiffness of the system 150 moving proximally along the length of the system 150 is shown. Figure 13B It is shown that the bending force at the distal end of the catheter advancement element 300 at P1 is significantly lower (e.g., at least greater by about 2 times) than the bending force at the distal end of the catheter 200 through which it extends. In some embodiments, the bending force at the distal end of the catheter advancement element 300 at P1 is not greater than about 0.05 N. The bending force of the catheter advancement element 300 can increase along the length of the distal tip portion 346 to approach the higher bending force at the distal end of the catheter 200. For example, the stiffness of the distal tip portion 346 can increase by at least 2 times along its length to approach the higher bending force at the distal end of the catheter 200. The catheter system 150 can have a generally constant slope along its length. This generally constant slope of the increasing bending force of the distal tip portion of the catheter advancement element 300 (shown as a dotted line in Figure 13B can transition to the generally constant slope of the increasing bending force of the combined system 150 (shown as a dashed line in Figure 13B such that there is no distinct step increase or slope change between the two. The bending force of the distal tip portion 346 can have a constant slope until it transitions to the constant slope of the system 150 as a whole (i.e., the additional bending force between the catheter 200 and the catheter advancement element 300 shown by the dashed line). The bending force of the catheter advancement element 300 can continue to increase along the length of the tip portion 346 (e.g., from P1 to P2 to P3 to P4), and then decrease again, for example, proximal to at least one engagement point (e.g., see P5 in Figure 13B ). The bending force of the catheter advancement element 300 can decrease proximal to this engagement point and remain significantly lower than the bending force of the catheter 200 over a certain length. In some embodiments, the proximal marker band 344b identifying the proximal end of the tapered distal tip 346 of the catheter advancement element 300 can be at this point (e.g., at Figure 13Blocally increase the stiffness of the catheter advancement element 300 near P3, P4, and S2, thereby minimizing the stepwise increase in stiffness from the distal tip 346 of the catheter advancement element 300 to the distal end of the catheter 200 of the assembly system 150. Tables 1, 3, 4, and 5 of Example 1 in the Experimental Section below describe the bending forces at various points along the length of different catheter systems.

[0210] The bending force along the length of the catheter system 150 can be used to calculate the slope of various parts of the system 150. The difference between the bending force at P2 and the bending force at P1 divided by the distance between P2 and P1 and / or the difference between the bending force at P3 and the bending force at P2 divided by the distance between P3 and P2 can provide the first flexural slope. The difference between the bending force at P3 and the bending force at P2 divided by the distance between P3 and P2 can provide the second flexural slope. The average of the first flexural slope and the second flexural slope can define the average tip flexural slope. In some embodiments, a fourth distal tip point can be measured such that the average tip flexural slope can take into account this additional segment (e.g., the segment between P3 and P4) when calculating the average slope. The difference between the bending force at S1 and the bending force at S2 (whether P3 or P4) divided by the distance between S1 and S2 (whether P3 or P4) can provide the first system flexural slope.

[0211] In some embodiments, the bending force at the distal end of the catheter advancement element 300 can be no greater than about 0.05 N. The average tip flexural slope can be at least about 0.005 N / mm. The system flexural slope can be between about 0.01 N / mm and about 0.03 N / mm. The ratio of the system flexural slope to the average tip flexural slope can be less than about 25, less than about 15, and preferably less than about 5, e.g., about 3 to about 1. The slope can be substantially constant or close to constant, and there is substantially no stepwise increase in the bending force slope from one segment to the next along the length of the catheter system 150. In particular, the catheter systems described herein avoid a large stepwise increase in the flexibility of the portion extending distally beyond the distal end of the catheter and the slope of the flexibility of the system as a whole (see also the Figures 14A - 14D ) described in Example 1 below.

[0212] The bending force at the distal tip of the catheter advancement element 300 at P1 can be a portion of the bending force of the distal end of the catheter 200, such as between about 5% and 15%. In contrast, the bending force at the engagement point (e.g., P3 or P4 or S2) on the catheter advancement element 300 proximal to the proximal end of the distal tip 346 can be about 50%–90% of the bending force (or flexibility) of the distal end of the catheter 200. Thus, the bending force at the engagement point of the catheter advancement element 300 can be closer to the bending force of the distal end of the catheter 200. In some embodiments, a portion of the catheter advancement element 300 proximal to the tapered distal tip 346 can have a length of about 5 cm to about 10 cm, and this portion can have a bending force (or flexibility) that is about 40% - 90% of the bending force of the distal end of the catheter 200.

[0213] The smooth transition of the flexibility along the length of the catheter system described herein provides optimal navigability without the risk of kinking. The catheter system described herein can have a particularly flexible distal end and transition to a particularly rigid proximal end to enable optimal torsion and manipulation. Thus, the bending force at P1 of the catheter advancement element 300 can be a portion of the bending force of a portion of the proximal portion 366 of the catheter advancement element 300. The proximal portion 366 can include at least one stiffness point within about 20 cm proximal to the tubular portion 360. The stiffness point can have a relatively high bending force, such as between about 5 N and about 15 N. The ratio of the bending force of the at least one stiffness point to the first bending force at P1 can be at least about 100, at least about 200, or at least about 300. The proximal portion 366 of the catheter advancement element 300 can be more than 300 times stiffer than the distal tip P1 of the catheter advancement element at P1. The bending force at the distal tip P1 of the catheter advancement element 300 can be no more than about 0.30% of the bending force of the proximal portion 366, such as between 0.10% and about 0.50%.

[0214] Method of Use

[0215] In Figure 15In the illustrated embodiment, the guide sheath 400 may be deployed such that the distal end of the sheath 400 is advanced to a location, for example, within the internal carotid artery (ICA). The sheath 400 may be advanced over a guide wire to the carotid artery using a pusher tool. The guide wire and the pusher tool (if used) may be removed or replaced with a smaller guide wire, which is further advanced distally into the cerebral vasculature, or there may be no guide wire at all, as described in more detail below. The first catheter 200a may be advanced through the working lumen of the guide sheath 400 and protrude from the distal end. The first catheter 200a may have a distal lumen portion 222a that is coupled to a proximal control element 230a. The proximal control element 230a may have a smaller outer diameter compared to the outer diameter of the distal lumen portion 222a and may be coupled near a proximal opening that begins at the lumen of the distal lumen portion 222a. The first catheter 200a may be advanced using a catheter pusher element without the assistance of a guide wire. The catheter pusher element may assist the first catheter 200a in advancing through the blood vessel without snagging on sharp angles and / or branched blood vessels. The first catheter 200a may be advanced through the working lumen of the guide sheath 400 and then through the blood vessel to a first target location. The catheter pusher element 300 may be removed from the lumen of the first catheter 200a. A second catheter 200b having a second catheter pusher element 300 may be advanced through the lumen of the first catheter 200a. The second catheter 200b may also include a distal lumen portion 222b that is coupled to a proximal control element 230b near a proximal opening of the lumen of the distal lumen portion 222b. Similar to the first catheter 200a, the proximal control element 230b of the second catheter 200b may have an outer diameter that is smaller than the outer diameter of the distal lumen portion 222b. The distal end of the second catheter 200b may be extended using its proximal control element 230b to extend beyond the distal end of the first catheter 200a such that the smaller diameter second catheter 200b may reach a target site in a distal blood vessel that has a narrower size compared to the location of the first catheter 200a. In this embodiment, the first stylet catheter 200a may be used as a support catheter for the second stylet catheter 200b. The second catheter 200b may be advanced to the appropriate location with or without a guide wire. When the second catheter pusher element 300 is removed, the internal lumen of the second stylet catheter 200b may be in fluid communication with the internal lumen of the first stylet catheter 200a, which is in fluid communication with the working lumen of the guide sheath 400, thereby forming an adjoining lumen formed by three portions that gradually increase in size toward the proximal end of the catheter system. For example, the first catheter 200a may have a distal lumen portion 222a with an inner diameter of approximately 0.088", and the second catheter 200b may have a distal lumen portion 222b with an inner diameter of approximately 0.070". More than two nested stylet catheters are contemplated, and their respective inner and outer diameters are sized to receive one another for use together. The corresponding ID and OD of the catheters may be sized such that they slide relative to one another but still provide sufficient sealing.For example, adjacent lumens formed by a nested arrangement can be sealed tightly against each other so that aspiration can be drawn through them, and appropriate pressure can be applied through the nested catheter to achieve, for example, a suction force sufficient for aspiration thrombectomy of a distant clot.

[0216] The proximal end of the nested catheter system can incorporate various grasping, handling, and attachment features. For example, the guide sheath 400 can include a proximal end coupled to a rotary hemostatic valve 434 that provides access to the working lumen into which the catheter can be inserted. Each component of the catheter system can project proximally from the valve 434. For example, the proximal control elements 230a, 230b of the catheters 200a, 200b can extend through the valve 434. The proximal extensions of their respective catheter advancement elements ( Figure 15 not shown in the figure) can also project proximally through the valve 434. Each of these components in the nested or telescoping catheter set can incorporate identifying features in their proximal regions to distinguish them from each other. For example, each proximal control element 230a, 230b can include tabs 234a, 234b having different shapes, colors, or other visual characteristics unique to that particular catheter. Each proximal control element 230a, 230b can include coupling parts, such as clips or other connectors, that manage the various control elements and prevent entanglement. The nested catheters and their respective catheter advancement elements can be incorporated in a kit.

[0217] The systems described herein are intended for use with a base sheath and a catheter that can pass through the sheath and have sufficient length to reach an intracranial target, such as the M1 segment of the middle cerebral artery. The use of a delivery catheter or catheter advancement element with a tapered tip allows for the delivery of a large-diameter catheter of full length "over-the-wire" catheter or a catheter having a proximal extension as described herein. The catheter advancement element can include a pair of radiopaque markers configured to assist the operator in delivering the system. The distal marker closest to the distal end of the catheter advancement element can be distinguished from the distal marker on the catheter by its characteristic appearance under fluoroscopy and by simply moving the atraumatic catheter advancement element slowly back and forth to understand the relationship and position of the catheter advancement element relative to the catheter. A second marker on the catheter advancement element near the most distal tip marker can delineate the tapered portion of the distal tip, i.e., the outer diameter of the catheter advancement element has sufficient dimensions to reduce the "lip" of the transition between the catheter advancement element and the catheter into which it is inserted and configured to deliver. The markers assist in positioning the catheter advancement element relative to the distal end of the large-diameter catheter such that the tip of the catheter is aligned with the tapered portion of the catheter advancement element and facilitate optimal alignment.

[0218] The relationship between the distal tip marker of the large-bore catheter and the tapered marker of the catheter advancement element, or ideally precisely proximal to the tapered marker of the catheter advancement element (i.e., the proximal marker identifying the start of the taper), can be identified using a tandem marker system. The paired elements are in a "tip-to-taper" position. The relative extension between the catheter advancement element and the catheter can be adjusted when the system is inserted into the RHV. However, the relative extension can change as the advancement through the sheath or guiding catheter progresses. As the system exits the guiding catheter and moves towards a more distal target across the often tortuous proximal vessels (such as the internal carotid artery), the large-bore catheter and the catheter advancement element can be adjusted to present a tip-to-taper position. The system of the large-bore catheter and the catheter advancement element can be locked in their relative extension to maintain the juxtaposition of the catheter advancement element and the large-bore catheter. When the large-bore catheter is visible within or even beyond the distal end of the sheath, the catheter advancement element can be adjusted to present an appropriate position relative to the catheter prior to further advancement. The optimal relative extension between the distal marker of the catheter and the tapered marker on the catheter advancement element can be maintained through as much of the anatomy as possible to maximize the delivery capabilities of the catheter advancement element, thereby navigating tortuous structures and avoiding side branches such as the ophthalmic artery. Once the target is reached, the catheter advancement element is held stationary, and then the large-bore catheter is advanced over the catheter advancement element towards the target without overshooting the target.

[0219] The catheter advancement element is specifically designed such that the catheter can be delivered without the need for a guidewire. This ability to deliver without dislodging emboli and without a guidewire is based on the smooth transition between the outer diameters of the catheter advancement element and the large-bore catheter and the smooth transition in flexibility between the two. When the catheter advancement element is bent into an arc greater than 180 degrees, the flexibility and pliability result in a smooth arc without significant bends or kinks in the geometry of the catheter. Thus, the catheter advancement element seeks out the larger lumen and reaches where most of the blood flow goes, rather than entering smaller branch arteries. The distal tip of the catheter advancement element can facilitate a greater tendency to seek out larger vessels during advancement into the distal vessels. This tendency to stay within the main channel allows the large-bore catheter to be advanced without the assistance of a guidewire. The tendency to follow the main blood flow channel is consistent with the pathophysiology of acute ischemic stroke, in which the main embolus tends to follow these same paths to the point where the embolus lodges and interrupts antegrade blood flow. Additionally, these main channels are often ideal for placing access catheters because these conduit arteries allow smaller catheters to enter specific target arteries for therapeutic intervention.

[0220] Standard neurovascular interventions, and nearly all endovascular interventions, are based on the concept of guiding a catheter to a target location with a guidewire. Guidewires are typically preformed, and often find side branches where the guidewire will bunch up or prolapse, creating a time-consuming nuisance during the intervention, which typically requires the operator to repeatedly re-guide the wire to overcome. Additionally, this tendency for the guidewire to enter side branches can be dangerous. Guidewires are typically 0.014” to 0.018” in neuroanatomy and will find and often traumatize small branches adapted to that size, which can lead to minor bleeding or dissection and occlusion. In a sensitive area such as the brain, these events can be catastrophic. The tendency for the guidewire to bunch up and prolapse can also cause the leading edge of the guidewire, which can be advanced alone or as part of a triaxial system, to form an anatomical plane and traumatize small blood vessels.

[0221] In contrast, the catheter advancement element described herein preferably stays within the larger lumen of the conduit vessel. In the case of stroke treatment, due to the blood flow drawn by the arterial system in the brain anatomy, emboli are driven to specific anatomical structures. The catheter advancement element tends to traverse the same path as the embolus will take, particularly emboli driven from locations such as cardiac or carotid etiologies. Even considering the highly tortuous anatomy and curves being navigated, the catheter advancement element is delivered to the largest lumen within the anatomy. The catheter advancement element can preferably take the larger lumen at branch points while also following the flow of the maximum blood flow, thus maintaining the general direction and angle of the parent vessel.

[0222] When observing the standard anatomical structures found in the cerebral vasculature, the Circle of Willis is supplied by two vertebral arteries and two carotid artery conduits. Since these four arteries are the entry points to the cerebral anatomy, the route of the catheter advancement element can be identified and has been verified in standard cerebral anatomical models. In the anterior circulation (the catheter arterial entry point for endovascular surgery of the cerebral vessels is the internal carotid artery (ICA)), the catheter advancement element can direct a large-bore catheter to the M1 segment of the middle cerebral artery (MCA). The very flexible nature of the catheter advancement element is combined with the distal flexibility of most cerebral catheters to allow delivery through extremely tortuous structures. Independent of the tortuous nature of the arterial route, the catheter advancement element tends to navigate turns and deliver from the parent artery to the largest offspring, e.g., from the ICA to the M1 segment of the MCA. The M2-level branches of the M1 can be variable but are generally considered to have two main M2 branches (superior and inferior branches) and, depending on the anatomy that can vary significantly between patients, can be considered to branch "equally" or "unequally". If the calibers of the M2 branches have similar dimensions and angles, the catheter advancement element can take either of the two branches. If the target for catheter placement is not at a favorable angle or size of the artery, the catheter advancement element may need to be bent (e.g., by shaping the distally extendable tip) and oriented or a guidewire may be used.

[0223] In some anatomies where the dimensions of the M2 branches are "uniform", back-and-forth movement can help select one branch and then the other while still avoiding the need for or use of a guidewire or the bent distal tip of the catheter advancement element. The back-and-forth movement can allow the catheter advancement element to be directed into either branch of the M2. Even if initially straight, the catheter advancement element can achieve a certain curvature that helps direct it into the branch vessel. Thus, when the operator encounters the M2 branches and wishes to cannulate either of the equally separated branches, the catheter advancement element can be used to select either branch without a guidewire.

[0224] Therefore, the main channels in the anterior circulation (e.g., ICA, middle cerebral artery and its tributaries) will naturally become the preferred routes for the catheter advancement element and subsequent delivery of the large-bore catheter (through the access from the ICA). A similar phenomenon may occur in the posterior circulation, which is accessed through the vertebral arteries originating from the subclavian arteries on both the left and right sides. The catheter advancement element will also take the main channels in this circulation by traversing the vertebral arteries to reach the basilar artery and the main tributaries of the basilar artery: the posterior cerebral artery and the superior cerebellar artery in the posterior circulation.

[0225] Navigation using a catheter advancement element can provide maximum deliverability with minimal vascular trauma. Since the blunt end of a large-bore catheter may tend to take a larger curve when rounding a blood vessel as it is pushed by an operator, the catheter can cause a "shaving" effect in a curved blood vessel. This blunt end may chisel out or "shave" a larger curve, and its sharp edges increase the risk of dissecting along the anatomical plane within medium- or large-sized arteries or veins in multiple layers (see, e.g., Catheter Cardiovasc.Interv. 2014 Feb;83(2):211-20). In such cases, placing a partially inflated balloon and a guide wire through the catheter can mitigate this "shaving" effect by separating the edges from the large-bore catheter. Similarly, a catheter advancement element can be used to minimize the edges of these catheters. Positioning the catheter advancement element within the lumen of the large-bore catheter to optimally align the tapered marker of the catheter advancement element with the distal tip marker of the catheter minimizes the edges, thereby eliminating the "shaving" when the large-bore catheter is advanced through a turn in the blood vessel. This is particularly useful for the cerebral anatomy. In the region distal to the carotid siphon (especially distal to the extremely tortuous larger curve of the "anterior knee" of the carotid siphon, which is typically considered part of the end of the internal carotid artery (ICA) and is the origin of the ophthalmic artery at the last turn "S-turn" of the carotid siphon), stroke treatment is often required. The details of the proper alignment of the catheter advancement element within the large-bore catheter relative to the tapered marker of the catheter advancement element (the "tip-to-taper" position indicated by the distal tip marker) maximize the likelihood of avoiding shaving and hanging on the ophthalmic artery. The tapered marker of the catheter advancement element can be positioned at or beyond the origin of the ophthalmic artery to minimize these adverse effects and allow the large-bore catheter to pass smoothly through the ophthalmic artery. In the relatively straight segment common after passing through the siphon, the large-bore catheter can be advanced over the catheter advancement element, which still serves as a guiding element to the target. In particular, compared to the stepped changes present in typical microcatheters or guide wires, the transition between the distal edge of the catheter advancement element and the large-bore catheter is not pronounced, thus not preventing hanging on branches such as the ophthalmic artery. The catheter advancement element allows the large-bore catheter to be maneuvered unobstructed to the surface of the embolus without the use of a microcatheter or guide wire and without in any way crossing and / or disrupting the embolus.

[0226] Conventional techniques for treating AIS, whether using a stent retriever, aspiration technique, or a combination of both, require using a guide wire and a microcatheter to cross the target occlusion. Crossing the embolus with a guide wire and then with a microcatheter can cause fragmentation of the occlusion, which may be friable and thrombotic in nature. Therefore, an aspiration technique is advantageous in which the embolus is completely removed without using any device to cross the occlusion.

[0227] In the case where the stent retriever does not have a "no cannula" passing through the embolus, the stent retriever cannot pass through or engage the target occlusion. ADAPT is a technique solely for frontline aspiration that avoids using a stent retriever to cross the target occlusion, thereby reducing the risk of fragmentation. However, the ADAPT method still requires both a guidewire and a microcatheter to cross the target occlusion (see Turk et al., J. Neurointerv. Surg. 2014 Apr 1;6(3):231-7). A guiding catheter such as the Neuron Max (Penumbra) is positioned as far distally as possible. The microcatheter and the microguidewire are advanced through the guiding catheter and distally to the occlusion. Using the microcatheter and the microguidewire as a support, a reperfusion catheter (e.g., Penumbra 5Max) is advanced to the occlusion. Aspiration is applied until the occlusion lodges or wedges within the tip of the reperfusion catheter. The reperfusion catheter is withdrawn and removed while maintaining aspiration and the occlusion within the catheter tip.

[0228] The systems described herein do not require the incorporation of a guidewire or a microcatheter. Moreover, when using a guidewire and a microcatheter, there is no need to advance them across the target occlusion. Thus, the systems described herein can incorporate relatively large-diameter catheters that are delivered without disturbing the target occlusion, thereby reducing the risk of stroke and downstream effects resulting from fragmentation of the occlusion, and having increased efficiency. Additionally, the systems described herein are single-operator systems that allow the operator to work under a single RHV, and in the case of spiked components, a single-handed "pinch" can be utilized to manipulate all elements for navigating the anatomy. This is sometimes referred to as "single-point."

[0229] As described above, the catheter advancement element can be coaxially disposed within a single lumen of the distal catheter portion, thereby forming a coaxial catheter system. The catheter can have a distal catheter portion and a proximal extension. The distal catheter portion can have an inner diameter defining a single lumen and a distal end defining a distal opening of the lumen. The proximal extension can be coupled to the distal catheter portion and extend proximally from the distal catheter portion. The catheter advancement element can have a tubular polymer portion having an inner diameter defining a lumen, a first outer diameter that is substantially uniform along its length, and a radiopaque marker band that is embedded within or located on the wall of the tubular polymer portion. The radiopaque marker band can create a second outer diameter that is distal to and greater than the first outer diameter. A tapered polymer tip can be located distal to the second outer diameter, which terminates at the distal opening of the lumen of the tubular portion. The length of the tapered polymer tip can be between about 0.5 cm and about 4 cm, such as between about 1 cm and about 3 cm, or about 2.5 cm. The catheter advancement element can further include a proximal extension that is coupled to the tubular polymer portion and extends proximally from the tubular polymer portion.

[0230] The coaxial catheter system may have a delivery configuration in which the tapered polymeric tip of the catheter advancement element extends distally beyond the distal end of the distal catheter portion, and the radiopaque marker band is substantially aligned with the distal end of the distal catheter portion, and the first outer diameter of the catheter portion is located within the lumen of the distal catheter portion.

[0231] The operator may work from a single RHV of the guiding sheath to manipulate both the catheter and the catheter advancement element. The coaxial catheter system may be advanced together so as to maintain the delivery configuration. The relative relationship between the radiopaque marker band on the catheter advancement element and a second marker band near the distal end of the catheter may assist in maintaining this delivery configuration during delivery. The operator may hold the two in relative position with a single clamp and advance the coaxial catheter system.

[0232] The coaxial catheter system may be advanced as far as possible until the catheter advancement element is at the surface of the embolus. The proximal extension of the catheter advancement element may be held "fixed" at the RHV, and the catheter is advanced over the catheter advancement element such that the distal end of the distal catheter portion is advanced over the catheter advancement element to the surface of the embolus. No guidewire or microcatheter is required to advance the coaxial catheter system to the surface of the embolus. Importantly, no device needs to penetrate the embolus.

[0233] Then, the catheter advancement element may be withdrawn from the coaxial catheter system and removed from the single RHV while the catheter is held in position at the surface of the embolus. The system is ready to begin aspiration, as will be described in more detail below.

[0234] In some embodiments, the first coaxial catheter system may not be able to reach the surface of the embolus. Thus, the catheter advancement element of the coaxial catheter system may be removed such that the lumen of the distal catheter portion is open, allowing the second coaxial catheter system to be advanced through the first catheter. The second coaxial catheter system may include a second catheter and a second catheter advancement element and is advanced in a manner similar to the first coaxial catheter system (i.e., by single-point manipulation), but through the first catheter which serves as a support catheter.

[0235] Once the catheter is in place at the surface of the embolus, the RHV may be sealed and aspiration may be initiated through the same RHV (e.g., through a side arm). The embolus may be aspirated from the body through the catheter solely by the aspiration pressure. Alternatively, when aspiration is applied to effect embolus removal, the catheter with the embolus plugged at the distal opening of the catheter may be slowly withdrawn, e.g., toward the lumen of the large-bore catheter.

[0236] Retrieving an embolus that is occluding the distal opening of a catheter back into the distal opening of a guiding sheath increases the risk of fragmentation and embolization, depending on the distance that must be retrieved before it is fully encapsulated within the lumen. Thus, it is desirable to use a nested system of sequentially larger catheter sizes to create a series of aspiration catheters, all of which operate from a single operating point through a single RHV. This allows the smallest caliber catheter to be advanced to the most distal side and withdrawn only a short distance into a larger caliber catheter, which can then aspirate the embolus completely, or, if necessary, withdrawn another short distance into a larger caliber catheter, which can aspirate the embolus from the body. Thereby, the likelihood of fragmentation of the captured clot is reduced, and the likelihood of aspirating the clot completely is increased.

[0237] The guiding sheath can be a large 7F sheath configured to receive a larger caliber catheter having an inner diameter of approximately 0.088", which in turn can receive an intermediate caliber catheter having an inner diameter of approximately 0.070", which in turn can receive a smaller caliber catheter having an inner diameter of approximately 0.054". Any of a variety of sizes are contemplated herein, and these examples are not intended to be limiting.

[0238] Although a larger caliber catheter can more effectively capture an embolus by aspiration, there is a likelihood that the significantly larger size of the larger caliber catheter can prevent its advancement to the embolus without additional manipulation. In some embodiments, a smaller caliber catheter extending through the lumen of the larger caliber catheter can be advanced to the surface of the embolus. The smaller caliber catheter (and its catheter advancement element) can be held stationary such that the larger caliber catheter is advanced as far as possible over the smaller caliber catheter. If the larger caliber catheter advancing on the larger aperture catheter can reach the embolus in this manner, the catheter advancement element can be removed from the smaller caliber catheter, the RHV can be closed to seal, and aspiration can be initiated. The distal end of the smaller caliber catheter and the distal end of the larger caliber catheter are both located at the surface of the embolus. The smaller caliber catheter can be removed from the system under continuous aspiration. If free flow is established with aspiration (e.g., visible by flow into the aspiration source), then after ensuring complete clearance of debris from the large caliber catheter with aggressive aspiration and flushing, the operator can leave the larger caliber catheter in place and consider whether to perform angiography to determine the establishment of antegrade flow and resolution of the occlusion. If free flow is not established, aspiration can continue, and after removing the smaller caliber catheter, the larger caliber catheter can be removed, thereby removing the embolus from the body by aspiration using the higher flow rate and force generated by the larger caliber catheter under full aspiration, provided that the smaller aperture catheter located within its lumen does not obstruct the flow. A single shared aspiration source can be used during the removal of both the smaller caliber catheter and the larger caliber catheter.

[0239] If the larger-diameter catheter cannot reach the target embolus by slowly advancing over the smaller-diameter catheter, the larger-diameter catheter and the catheter advancement element for the smaller-diameter catheter can be held fixed at the RHV such that the smaller-diameter catheter can be advanced between them to the surface of the embolus. The smaller-diameter catheter can then provide a track for another attempt to advance the larger-diameter catheter toward the surface of the embolus. These steps can be repeated in sequence to "slowly move" the larger-diameter catheter toward the embolus until the distal ends of both the smaller-diameter catheter and the larger-diameter catheter are near the surface of the embolus such that aspiration thrombectomy can be performed through them.

[0240] The smaller-diameter catheter can be attached to the embolus and the embolus withdrawn toward the larger-diameter catheter. Thus, in cases where the embolus may be too large to fully enter the lumen of the smaller-diameter catheter, the embolus can be enveloped or retrieved by the lumen of the larger-diameter catheter. The smaller-diameter catheter with the embolus attached to its distal end by aspiration can be withdrawn and then immediately the embolus can be captured and withdrawn through the larger-diameter catheter under aspiration.

[0241] Tension can be stored in a catheter system advanced through tortuous brain anatomy. When the distal end of the catheter encounters resistance, downward and lateral forces may be generated on the support catheter system. When the distal tip of the catheter is released past these resistance points, the entire system can be advanced forward. Resistance can occur at vascular tortuosities or occlusions or bifurcations, or due to pre-existing implants or other reasons. Generally, the tension is stored without loss of position. The resulting effect is a back-and-forth movement of the system to reach the target, as well as a steady storage of tension in the guiding sheath as it is continuously pushed downward (i.e., backward in the proximal direction opposite the insertion direction).

[0242] In the case of aspiration systems for stroke, as a larger diameter catheter (e.g., a 0.088” ID catheter) is advanced, the same stored tension occurs. As the larger diameter catheter creates stored tension and the operator attempts to advance it to the target embolus (e.g., in the M1 branch of the MCA), the larger diameter catheter traverses the anatomy in a “larger curve to larger curve” manner, introducing a certain amount of slack force into the system. The stored tension creates resistance that can cause the catheter to get stuck at a point and not reach the target. If the larger diameter catheter does not reach the target, a smaller diameter catheter can be advanced to reach the embolus due to its smaller diameter and better deliverability. The smaller diameter catheter can navigate the stored tension as well as the larger diameter catheter, and also navigate the anatomy in a “larger curve to larger curve” manner. The smaller diameter catheter can be anchored to the embolus via aspiration pressure applied through the system. The smaller diameter catheter can be fixed at the occlusion point, and the aspiration is opened to maximum (e.g., via a pump). This fixes or anchors the smaller diameter catheter to the embolus such that the operator can “straighten” the entire system, thereby applying a proximally directed force to the smaller diameter catheter to eliminate the slack relative to the surrounding anatomy while the distal end of the smaller diameter catheter remains anchored to the occlusion. Once the slack is reduced, the catheters now traverse the anatomy in a “smaller curve to smaller curve” manner rather than a “larger curve to larger curve” manner, thus straightening their path relative to the surrounding anatomy. The straightened path allows the larger diameter catheter to be advanced over the anchored smaller diameter catheter so that its distal end can also reach the embolus target. The aspiration and anchoring through the smaller diameter catheter are maintained, and the operator creates a straighter, tension-free path to “deliver” the larger diameter catheter over the smaller diameter catheter. Once the larger diameter catheter is in place—even if the larger diameter catheter does not reach the embolus—adequate embolic protection can be provided and embolization off-target can be avoided, especially if the larger diameter catheter is distal to the branch closest to the embolus site.

[0243] Once the larger diameter catheter is in place, the smaller diameter catheter extending through it can be withdrawn. As the smaller diameter catheter is withdrawn toward the distal end of the larger diameter catheter, aspiration can still be applied through a single aspiration source, and the seal between the occluded emboli can be maintained. Once the smaller diameter catheter is pulled into the distal end of the larger diameter catheter, the aspiration pressure can be automatically opened within the larger diameter catheter, thereby capturing the embolus within the lumen of the larger diameter catheter. Due to the larger inner diameter, the embolus may be evacuated under continuous aspiration pressure through a single shared aspiration source. Both the smaller diameter catheter and the larger diameter catheter can be withdrawn from the system.

[0244] Material

[0245] One or more components of the catheter described herein may comprise or be made of a variety of materials, including one or more of the following: metals, metal alloys, polymers, metal-polymer composites, ceramics, hydrophilic polymers, polyacrylamide, polyethers, polyamides, polyethylene, polyurethane, its copolymers, polyvinyl chloride (PVC), PEO, PEO-impregnated polyurethane, such as hydrogenated ethane, thermophilic polyurethane, tetrahydrofuran, PEO soft-segment polyurethane blended with Tecoflex, thermoplastic starch, PVP, and combinations thereof, or other suitable materials.

[0246] Some examples of suitable metals and metal alloys include: stainless steels, such as 304V, 304L, and 316LV stainless steels; mild steel; nitinol alloys, such as wire elastic and / or superelastic nitinol alloys; other nickel alloys, such as nickel-chromium-molybdenum alloys (e.g., UNS:N06625, such as 625; UNS:N06022, such as UNS:N10276, such as others alloys, etc.), nickel-copper alloys (e.g., UNS:N04400, such as 400, 400, 400, etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS:R30035, such as MP35- etc.), nickel-molybdenum alloys (e.g., UNS:N10665, such as ), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, etc.; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS:R30003, such as etc.); platinum-rich stainless steels; titanium; combinations thereof; and the like; or any other suitable materials as described elsewhere herein.

[0247] The inner lining material of the catheter described herein may include low-friction polymers such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene), PTFE with a polyurethane layer (Tecoflex). The reinforcing layer material of the catheter described herein may be bonded to provide mechanical integrity for applying torque and / or preventing flattening or kinking, for example metals including stainless steel, nitinol, nitinol braids, helical bands, helical wires, cut stainless steel, etc. Or rigid polymers such as PEEK. The reinforcing fiber material of the catheter described herein may include various high-strength polymers such as Kevlar, polyester, meta-aramid, PEEK, single fibers, multi-fiber bundles, high tensile strength polymers, metals or alloys, etc. The sleeve material of the catheter described herein may provide mechanical integrity and may include a variety of materials such as polyethylene, polyurethane, PEBAX, nylon, tetrahydrofuran, etc. Other coating materials of the catheter described herein include parylene, polytetrafluoroethylene, silicone, polyimide-polytetrafluoroethylene, etc.

[0248] Examples

[0249] Using systems such as Figure 12 shown for measuring bending force to test the catheter systems described herein, and data are provided below. The first catheter system incorporates a catheter advancement element whose outer diameter is sized to extend through a catheter (Form A) having an inner diameter of approximately 0.054”. The second catheter system includes a catheter advancement element whose outer diameter is sized to extend through a catheter (Forms B1 and B2) having an inner diameter of approximately 0.070”. The third catheter system includes a catheter advancement element whose outer diameter is sized to extend through a catheter (Form C) having an inner diameter of approximately 0.088”.

[0250] At least three points along the tapered tip of the catheter advancement element were tested (see Figures 13A - 13B P1, P2, P3, P4). The distal point P1 among the at least three points is located at a distance of approximately 5 mm proximal from the most distal end of the catheter advancement element. The second point P2 of the distal tip is the midpoint of the at least three points located at a distance proximal from the distal point P1. For Form A, the second point P2 is at approximately 12 mm proximal from the most distal end of the catheter advancement element. For Forms B1, B2, and C, the second point P2 is at approximately 20 mm proximal from the most distal end of the catheter advancement element. The proximal point P3 among at least these points may be located at a distance proximal from the midpoint P2, and for Form A, it is at approximately 13 mm proximal from the most distal end of the catheter advancement element, while for Forms B1, B2, it is at approximately 25 mm proximal from the most distal end of the catheter advancement element. Some catheter system forms include a fourth point P4. For Forms B1, B2, and C, P4 is measured at approximately 27 mm, 27 mm, and 28 mm, respectively.

[0251] Place the catheter system in the advancement configuration and soak it in a 37 °C bath for a period of time before testing. The experimental advancement configuration is when the catheter advancement element is coaxially located within the lumen of the distal catheter portion of the catheter such that at least one mating point of the tubular portion is substantially aligned with the distal end of the catheter, and the distal tip of the catheter advancement element extends distally beyond the distal end of the catheter. The area near P3 on the catheter advancement element forms a mating point with the catheter, where the difference between the inner diameter and the outer diameter at the mating point is no greater than about 0.010”. For Form A, the difference is about 0.006”, while for Forms B1 and C, the difference is about 0.008”. Each of the points P1, P2, P3, and P4 (when applicable) is located on the tip of the catheter advancement element and extends distally beyond the distal end of the catheter.

[0252] For all forms, a fifth point P5 is measured, and a bending force is applied to the catheter advancement element only proximal to the mating point (see Figure 13B ). When the system is in the advancement configuration, the fifth point P5 is located at a position inside the catheter, but P5 only takes into account the bending force measurement of the catheter advancement element. For Form A, this fifth point P5 is measured at approximately 16 mm proximal to the distal end of the catheter advancement element. For Forms B1 and C, the fifth point P5 is located at approximately 30 mm proximal to the distal end of the catheter advancement element. When the components of the catheter system are in the advancement configuration, this fifth point P5 on the catheter advancement element can be located inside the catheter. Therefore, P5 is measured on the catheter advancement element in the absence of the catheter.

[0253] At least two points along the catheter system are also tested to measure the bending force of the system when in the advancement configuration (see Figures 13A - 13B for S1 and S2). The first system point S1 takes into account the combined bending force of the catheter and the catheter advancement element extending through the catheter and is represented by a dashed line in Figure 13B . For Form A, the first system point S1 of the at least two system points is located proximal to the distal end of the catheter at a gage length of approximately 5 mm or approximately 19 mm from the most distal end of the catheter system. For Forms B1 / B2 and C, the first system point S1 of the at least two system points is located proximal to the distal end of the catheter at gage lengths of approximately 50 mm and approximately 34 mm, respectively, from the most distal end of the catheter system.

[0254] The second system point S2 of the at least two system points is located a distance distally from the first system point S1. The second system point S2 takes into account the bending force of the catheter advancement element extending outside the catheter. In some tests, the second system point S2 is located distally beyond the distal end of the catheter and is the same as the proximal point P3 or the proximal point P4 (if any).

[0255] Table 1 below provides the bending forces measured in Newtons (N) at various points along the length of the catheter system in the advancement configuration. The points referred to in the table are typically related to Figures 13A - 13B the points shown, but are not shown to scale. These points are merely exemplary, and different points may be measured.

[0256] Table 1

[0257]

[0258] Table 1 shows that the bending force at the distal end of the catheter advancement element at P1 is not greater than about 0.05 N. The difference between the bending force at P2 and the bending force at P1 divided by the distance between P2 and P1 and / or the difference between the bending force at P3 and the bending force at P2 divided by the distance between P3 and P2 provides the first flexural slope. The first flexural slope is about 0.008 N / mm for Form A, 0.010 N / mm for Form B1, and 0.012 N / mm for Form C. The difference between the bending force at P3 and the bending force at P2 divided by the distance between P3 and P2 provides the second flexural slope. The second flexural slope is about 0.008 N / mm for Form A, 0.006 N / mm for Form B1, and 0.007 N / mm for Form C. The average of the first flexural slope and the second flexural slope defines the average tip flexural slope. In some tests, a fourth distal tip point is measured such that the average tip flexural slope takes into account this additional segment (e.g., the segment between P3 and P4) when calculating the average slope. For each form of the catheter system tested, the average tip flexural slope is at least 0.005 N / mm. For example, the average tip flexural slope is about 0.008 N / mm for Form A and Form B1, and about 0.010 N / mm for Form C. The difference between the bending force at S1 and the bending force at S2 (either P3 or P4) divided by the distance between S1 and S2 (either P3 or P4) provides the first system flexural slope. The first system flexural slope using P3 as S2 is about 0.024 N / mm for Form A, 0.013 N / mm for Form B1, and about 0.009 N / mm for Form C. In this calculation, the ratio of the first system flexural slope to the average tip flexural slope is about 3.0 for Form A, about 1.6 for Form B, and about 0.9 for Form C. The first system flexural slope using P4 as S2 is about 0.035 N / mm for Form B1 and about 0.02 N / mm for Form C. In this calculation, the ratio of the first system flexural slope to the average tip flexural slope is about 4.4 for Form B1 and about 2.0 for Form C. Regardless of which point is used as S2 (either P3 or P4), for each form, the ratio of the first system flexural slope to the average tip flexural slope is less than about 5.

[0259] Figures 14A - 14D The bending force at each of the above points is shown relative to the distance in millimeters along the length of the system. Figure 14A Data for the Form A system is shown, which incorporates a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of approximately 0.054". Figure 14B Data for the Form B1 system is shown, which incorporates a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of approximately 0.070". Figure 14C Data for another form (Form B2) of the catheter system is shown, which incorporates a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of approximately 0.070". Figure 14D Data for the Form C system is shown, which incorporates a catheter advancement element 300 having an outer diameter sized to extend through a catheter having an inner diameter of approximately 0.088".

[0260] Figures 14A - 14D It is shown how the slope of the line is substantially constant or close to constant from one segment to the next along the length of the catheter system, and there is substantially no step - increase in the bending - force slope. In particular, for each form tested, there is no step - increase in the bending force between the distal tip point (i.e., the point distal to where the catheter advancement element extends to the distal end of the catheter) and the system point (i.e., the combination of the catheter and the catheter advancement element). Thus, when in the advancement configuration, the overall slope of the system is substantially constant over the entire length of the system, e.g., its length is from the most distal end of the system (0 mm) to approximately 35 mm proximal from the most distal end.

[0261] In each form tested, the bending force at the distal end of the catheter advancement element at P1 is significantly lower (e.g., at least about 2 times greater) than the bending force at the distal end of the catheter through which it extends (see also Table 4 below). The bending force at the distal end of the catheter advancement element at P1 is not greater than approximately 0.05 N. The bending force of the catheter advancement element increases over the length of the distal tip portion to approach the higher bending force of the distal end of the catheter. For example, the stiffness of the distal tip portion increases by at least 2 times over its length to approach the bending force of the distal end of the catheter. The bending force of the catheter system has a generally constant slope over its length. This generally constant slope of the increasing bending force of the distal tip portion of the catheter advancement element (shown as a dotted line in Figure 13B transitions to the generally constant slope of the increasing bending force of the combined system (in Figure 13Bshown as a dashed line), such that there is no significant step - increase in the slope between the two. The slope of the bending force at the distal tip transitions to the slope of the system as a whole (i.e., the additional bending force between the catheter and the catheter advancement element shown by the dashed line), and there is no significant step - increase in the slope from one segment to the next.

[0262] As a comparison, corresponding points on different catheter systems (GUIDELINER navigation catheter system; Vascular Solutions, Minneapolis, Minnesota) were tested. This data is provided in Table 2 below and Figure 14E is provided in Figure 14E shows the bending force at various points along the length of the GUIDELINER system relative to the distance in millimeters.

[0263] Table 2

[0264]

[0265]

[0266] The first bending force of P1 is greater than 0.05 N, specifically about 0.114 N. Various calculations were performed using the bending force data shown in Table 2. The first deflection slope of the GUIDELINER system is about 0.005 N / mm. The second flexural slope of the GUIDELINER system is about 0.001 N / mm. The average tip flexural slope of the GUIDELINER system is about 0.003 N / mm. The first system flexural slope of the GUIDELINER system is about 0.10 N / mm. The ratio of the first system flexural slope of the GUIDELINER system to the average tip flexural slope is greater than 30. This ratio numerically illustrates the situation visible in the Figure 14E graph. Figure 14E shows a step - increase in the slope of the GUIDELINER catheter system experiencing the flexure from the extension of the navigation catheter to the distal part of the catheter through which it extends and the flexure of the system as a whole. These step - increases in the large slopes imply a sharp transition in stiffness along the length of the catheter system, thus preventing the GUIDELINER catheter system from advancing around the curves of tortuous blood vessels through the bony anatomy of the skull. In contrast, the catheter systems described herein have a smaller slope ratio, which indicates that they have as smooth a transition in stiffness from the distal end to the proximal end as possible, and are thus suitable for delivery through tortuous anatomy.

[0267] Table 3 below shows the slope of the catheter system described herein compared to the slope of the GUIDELINER navigation catheter system. The "average tip flexibility slope" was calculated. More specifically, the average tip flexibility slope is the average of the slopes of segments P1 to P2, P2 to P3, and P3 to P4 (when available). Additional segments of the tip may be included. The "slope of segment S2 - S1" is the slope of the segment between system points S2 and S1. System point S2 may be the same or different from one of the other points (e.g., P4 or P3). The "slope of segment P1 - S1" is the slope of the line drawn directly from the most distal point P1 to system point S1.

[0268] Table 3

[0269]

[0270]

[0271] The tapered distal tip experiences a change in bending force over its length that is at least 2 times greater. The tapered distal tips of the catheter advancement elements of forms A, B1, B2, and C have a minimum slope of at least 0.005 N / mm. In contrast, the GUIDELINER experiences an increase in bending force over its length of only about 1.2 times. Additionally, the GUIDELINER has an average tip flexibility slope of less than about 0.003 N / mm. The slope of each catheter system (forms A, B1, B2, and C) from the distal point P1 to the system point S1 increases by no more than about 5 times, while the GUIDELINER increases by more than 30 times from 0.114.

[0272] Table 4 below shows the bending force of the distal tip of the catheter advancement element relative to the bending force of the distal end of the catheter. The point measured and referred to as "Catheter Point C1" in Table 4 below is the point along the length of the catheter closest to the distal end, which can be measured using the system described herein, e.g., a gauge length of at least about 5 mm from the most distal end of the catheter. The bending force (or flexibility) of the distal tip at P1 is about 16% of the bending force (or flexibility) of C1 for Form A, about 10% for Form B1, and about 8% for Form C. Thus, the bending force at P1 is between about 5% and 15% of the bending force at C1. The bending force (or flexibility) of the conforming points (e.g., P3 or P4) proximal to the proximal end of the distal tip is about 59% for Form A, about 91% for Form B1, and about 82% for Form C.. Thus, the bending force at the conforming point is between about 50% and 90% of the bending force (or flexibility) of C1. In contrast, the distal tip point P1 on the GUIDELINER is more rigid compared to the same points on Forms A, Bl, or C. The proximal point P3 on the GUIDELINER has a greater bending force compared to its distal tip point P1, but this bending force is much lower compared to the bending force of Catheter Point C1 (i.e., only 23% of the stiffness of Catheter Point C1). Thus, there is a greater difference between the bending force of the navigation catheter at P3 and the bending force of the catheter at C1 compared to the forms of the catheter systems described herein. As Figure 14E best seen in, this difference results in a relatively large stepped increase in the slope of the GUIDELINER catheter system.

[0273] Table 4

[0274]

[0275] Table 5 below shows the bending force of P1 of the catheter advancement element relative to the bending force of the proximal extension of the catheter advancement element. The point E1 on the proximal extension selected for testing is within about 20 cm proximal from the tubular portion of the catheter advancement element. Point E1 has a bending force of about 9.21 N. The bending force of the catheter advancement element at the distal tip P1 is not greater than about 0.30% of the bending force of the proximal extension at E1. The ratio of the bending force of Point E1 to the first bending force at the distal tip P1 is at least about 300. At P1, the proximal extension of the catheter advancement element of Form C is about 318 times more rigid than the distal tip of the catheter advancement element, about 368 times more rigid for Form B1, and about 400 times more rigid for Form A.

[0276] Table 5

[0277]

[0278] For comparison, two other catheter systems were analyzed. The GUIDELINER steerable catheter has a greater bending force at E1 than any of the forms tested at 17.52 N. The bending force at the distal tip P1 is likewise higher compared to the form of the catheter system described herein. The bending force of the steerable catheter at the distal tip P1 is approximately 0.65% of the bending force of the proximal extension at E1. Additionally, the bending force at point E1 of the GUIDELINER steerable catheter is only 154 times that of the distal tip P1. The ORION-21 catheter (Medtronic, Minneapolis, Minnesota) has a bending force at the distal tip P1 that is approximately 1.64% of the bending force at E1. The bending force at point E1 of the ORION-21 is only approximately 60 times stiffer than its distal tip at P1.

[0279] The data described herein provide a numerical picture of a smooth transition in flexibility along the lengths of the various catheter systems described herein, which provides optimal navigability without the risk of kinking. The catheter systems described herein have a particularly flexible distal end that transitions towards a particularly rigid proximal end to achieve optimal torsional and manipulative capabilities. Manage the flexible transition along the length of the system so that the two components work seamlessly together as if they were a single component, and from one section to another, there is no large stepwise increase in stiffness.

[0280] Embodiments describe a catheter and a delivery system and method for delivering the catheter to a target anatomy. However, although some embodiments are specifically described for delivering a catheter to a target vessel in a neurovascular anatomy (e.g., a cerebrovascular vessel), these embodiments are not limited thereto, and certain embodiments may also be applicable to other uses. For example, the catheter may be adapted for delivery to different neuroanatomies, such as the subclavian artery, vertebral artery, carotid vessels, as well as for delivery to a coronary anatomy or a peripheral vascular anatomy, to name just a few possible applications. Although the systems described herein are described as being useful for treating a particular condition or lesion, the condition or lesion being treated may vary and is not limiting. The use of terms such as "embolus," "embolism," "embolic," "thrombus," "occlusion," "clot," etc. in relation to the targets of treatment using the devices described herein is not intended to be limiting. These terms are used interchangeably and may include, but are not limited to, blood clots, air bubbles, small fat deposits, or other objects carried in the blood to a distant location or formed at a location within a blood vessel. These terms are used interchangeably herein to refer to something that may cause partial or complete occlusion of the blood flow through a blood vessel or within a blood vessel.

[0281] In various embodiments, the description is made with reference to the accompanying drawings. However, a particular embodiment may be practiced without one or more of these specific details or in combination with other known methods and configurations. In the specification, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail so as not to unnecessarily obscure the description. Throughout the specification, references to "one embodiment", "an embodiment", "one implementation", "an implementation", etc. mean that the particular feature, structure, configuration, or characteristic described is included in at least one embodiment or implementation. Thus, the phrases "one embodiment", "an embodiment", "one implementation", "an implementation", etc. that appear throughout the specification are not necessarily referring to the same embodiment or implementation. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

[0282] The use of relative terms throughout the specification may denote relative position or direction. For example, "distal" may indicate a first direction away from a reference point. Similarly, "proximal" may indicate a position in a second direction opposite the first direction. The reference point used herein may be the operator such that the terms "proximal" and "distal" are referenced to the operator using the device. The region of the device closer to the operator may be described herein as "proximal", while the region of the device farther from the operator may be described herein as "distal". Similarly, the terms "proximal" and "distal" may also be used herein to refer to the anatomical position of a patient from the perspective of the operator or from the point of entry or along the insertion path from the point of entry of the system. Thus, a proximal position may refer to a position within the patient along the insertion path towards the target that is closer to the point of entry of the device, while a distal position may refer to a position within the patient along the insertion path towards the target position that is farther from the point of entry of the device. However, these terms are provided to establish a relative frame of reference and are not intended to limit the use or orientation of the catheter and / or delivery system to the specific configurations described in the various embodiments.

[0283] Although this specification contains many details, these details should not be construed as limitations on the scope of the claims or the scope of what may be claimed, but rather as descriptions of specific features of particular embodiments. Specific features described in the context of separate embodiments in this specification can also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment can also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although the features above may be described as acting in a particular combination and even initially so claimed, in some cases, one or more features of the claimed combination can be removed from the combination, and the claimed combination can be directed to a sub-combination or a variation of the sub-combination. Similarly, although the operations are depicted in the drawings in a particular order, this should not be construed as requiring that the operations be performed in the particular order shown or in a sequential order, or that all of the operations shown be performed to obtain the desired result. Only a few examples and embodiments are disclosed. Changes, improvements, and enhancements can be made to the described examples and embodiments and other embodiments based on what is disclosed.

[0284] In the above description, phrases such as "at least one" or "one or more" may appear, followed by a list of elements or features. The term "and / or" may also appear in a list of two or more elements or features. Unless the context in which it is used implies otherwise or is clearly contradictory thereto, this phrase is intended to mean any of the elements or features listed individually, or any combination of any of the referenced elements or features with any other referenced element or feature. For example, the phrases "at least one of A and B", "one or more of A and B", and "A and / or B" are each intended to mean "A alone, B alone, or A and B together". Similar interpretations apply to lists including three or more items. For example, the phrases "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, and / or C" are intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together".

[0285] The use of the term "based on" above is intended to mean "at least partially based on", such that features or elements not recited are also permitted.

[0286] 1. A catheter system, the system comprising:

[0287] a catheter including a lumen and having a distal end from an opening of the lumen; and

[0288] a catheter advancement element including:

[0289] a tubular portion having an inner diameter and an outer diameter;

[0290] A conical tip, located distally of the tubular portion, wherein the length of the conical tip is at least 1 centimeter to 4 centimeters; and

[0291] A radiopaque marker band that identifies the proximal end of the conical tip,

[0292] wherein the catheter system has an assembled configuration, characterized in that the catheter advancement element is located within the lumen of the catheter, and the radiopaque marker band is substantially aligned with the distal end of the catheter, and

[0293] wherein the radiopaque marker band locally increases the stiffness of the catheter advancement element, and wherein, when the catheter and the catheter advancement element are in the assembled configuration, the radiopaque marker band minimizes the stepwise increase in bending force from the conical tip to the distal end of the catheter.

[0294] 2. The catheter system according to item 1, wherein the bending force of the catheter advancement element increases along the length of the conical tip to the radiopaque marker band, and wherein the bending force of the catheter advancement element decreases near the radiopaque marker band.

[0295] 3. The catheter system according to item 1, wherein the radiopaque marker band is embedded within the wall of the tubular portion or is located above the wall of the tubular portion.

[0296] 4. The catheter system according to any one of items 1-3, wherein a first radiopaque marker band is located at the distal end of the conical tip, and a second radiopaque marker band is located at the proximal end of the conical tip.

[0297] 5. The catheter system according to item 4, wherein the second radiopaque marker band has a proximal edge, a distal edge, and a width between the proximal edge and the distal edge, and the proximal edge of the second radiopaque marker band is substantially aligned with the distal end of the catheter such that the second radiopaque marker band remains outside the lumen of the catheter.

[0298] 6. The catheter system according to item 1, wherein the catheter advancement element includes a flexible elongate body coupled to a proximal portion, and the proximal portion transitions from a highly flexible distal region of the catheter advancement element to a less flexible proximal region of the catheter advancement element.

[0299] 7. The catheter system according to item 1, wherein the tubular portion has a region of relatively uniform outer diameter that extends along at least a portion of the length of the tubular portion.

[0300] 8. The catheter system according to item 1, wherein the tapered tip portion has a flexible transition along the length of the tapered tip portion.

[0301] 9. The catheter system according to item 8, wherein the tapered tip portion has an overall maximum flexibility at the most distal end of the tapered tip portion.

[0302] 10. The catheter system according to item 8, wherein the transition from the flexibility of the tapered tip portion to the flexibility of the catheter system as a whole is defined by a slope that does not include an obvious step increase and is substantially constant.

[0303] 11. The catheter system according to item 1, wherein the ratio of the bending force of the proximal portion of the tapered tip portion to the bending force of the distal point of the tapered tip portion is at least 2.

[0304] 12. The catheter system according to item 1, wherein the additional bending force between the catheter and the catheter advancement element of the catheter system gradually increases from the distal end of the catheter system towards the proximal end of the catheter system.

[0305] 13. The catheter system according to item 12, wherein the additional bending force gradually increases without a step increase in slope.

[0306] 14. A catheter system, the system comprising:

[0307] A catheter, comprising a lumen and a distal end having an opening from the lumen; and

[0308] A catheter advancement element, comprising:

[0309] A tubular portion having an inner diameter and an outer diameter; and

[0310] A tapered tip portion located distally of the tubular portion,

[0311] wherein the alignment point of the catheter advancement element is proximal to the tapered tip portion;

[0312] wherein the catheter system has an assembled configuration, characterized in that:

[0313] a) The catheter advancement element is located within the lumen of the catheter, wherein the alignment point of the catheter advancement element is substantially aligned with the distal end of the catheter, and

[0314] b) wherein, in the assembled configuration, the tapered tip portion has at least three points spaced along the length of the tapered tip portion, the at least three points including:

[0315] The distal point among the at least three points, the distal point being located 5 mm proximally from the most distal end of the catheter advancement element, the distal point having a first bending force;

[0316] The middle point among the at least three points, the middle point being located 12 mm proximally from the most distal end of the catheter advancement element, the middle point having a second bending force; and

[0317] The proximal point among the at least three points, the proximal point being located 13 mm proximally from the most distal end of the catheter advancement element, the proximal point having a third bending force; and

[0318] c) wherein the catheter system has at least two system point...

Claims

1. A catheter system, the system comprising: a catheter including a lumen and a distal end having an opening from the lumen; and a catheter advancement element including: a tubular portion having an inner diameter and an outer diameter; a tapered tip portion located distally of the tubular portion, wherein the length of the tapered tip portion is at least 1 centimeter to 4 centimeters; and a radiopaque marker band identifying the proximal end of the tapered tip portion, wherein the catheter system has an assembled configuration, characterized in that the catheter advancement element is located within the lumen of the catheter, and the radiopaque marker band is substantially aligned with the distal end of the catheter, and wherein the radiopaque marker band locally increases the stiffness of the catheter advancement element, and wherein when the catheter and the catheter advancement element are in the assembled configuration, the radiopaque marker band minimizes a stepwise increase in bending force from the tapered tip portion to the distal end of the catheter.

2. The catheter system according to claim 1, wherein, The bending force of the catheter advancement element increases along the length of the tapered tip portion to the radiopaque marker band, and wherein the bending force of the catheter advancement element decreases near the radiopaque marker band.

3. The catheter system according to claim 1, wherein, The radiopaque marker band is embedded within the wall of the tubular portion or located above the wall of the tubular portion.

4. The catheter system according to any one of claims 1-3, wherein, A first radiopaque marker band is located at the distal end of the tapered tip portion, and a second radiopaque marker band is located at the proximal end of the tapered tip portion.

5. The catheter system according to claim 4, wherein, The second radiopaque marker band has a proximal edge, a distal edge, and a width between the proximal edge and the distal edge, and the proximal edge of the second radiopaque marker band is substantially aligned with the distal end of the catheter such that the second radiopaque marker band remains outside the lumen of the catheter.

6. The catheter system according to claim 1, wherein, The catheter advancement element includes a flexible elongate body coupled to a proximal portion, and the proximal portion transitions from a highly flexible distal region of the catheter advancement element to a less flexible proximal region of the catheter advancement element.

7. The catheter system according to claim 1, wherein The tubular portion has a region of relatively uniform outer diameter extending along at least a portion of the length of the tubular portion.

8. The catheter system according to claim 1, wherein, The tapered tip portion has a flexible transition along the length of the tapered tip portion.

9. The catheter system according to claim 8, wherein, The tapered tip portion has an overall maximum flexibility at the most distal end of the tapered tip portion.

10. The catheter system according to claim 8, wherein, The transition from the flexibility of the tapered tip portion to the flexibility of the catheter system as a whole is defined by a slope that does not include an obvious stepwise increase and is substantially constant.

11. The catheter system according to claim 1, wherein, The ratio of the bending force of the proximal portion of the tapered tip portion to the bending force of the distal point of the tapered tip portion is at least 2.

12. The catheter system according to claim 1, wherein, The additional bending force between the catheter and the catheter advancement element of the catheter system gradually increases from the distal end of the catheter system towards the proximal end of the catheter system.

13. The catheter system according to claim 12, wherein, The additional bending force gradually increases without a stepwise increase in slope.

14. A catheter system, the system comprising: a catheter including a lumen and a distal end having an opening from the lumen; and a catheter advancement element including: a tubular portion having an inner diameter and an outer diameter; and a tapered tip portion located distally of the tubular portion, wherein the alignment point of the catheter advancement element is located proximally of the tapered tip portion; Among them, the catheter system has an assembled configuration, characterized in that: a) The catheter propulsion element is located within the lumen of the catheter, wherein the alignment point of the catheter propulsion element is substantially aligned with the distal end of the catheter, and b) Wherein, in the assembled configuration, the tapered tip has at least three points spaced along the length of the tapered tip, and the at least three points include: The distal point among the at least three points, the distal point is located 5 mm proximal from the most distal end of the catheter propulsion element, and the distal point has a first bending force; The middle point among the at least three points, the middle point is located 12 mm proximal from the most distal end of the catheter propulsion element, and the middle point has a second bending force; and The proximal point among the at least three points, the proximal point is located 13 mm proximal from the most distal end of the catheter propulsion element, and the proximal point has a third bending force; and c) Wherein, the catheter system has at least two system points along the length of the catheter system, and the at least two system points include: The first system point among the at least two system points, the first system point is located 19 mm proximal from the most distal end of the catheter system, and the first system point has a first system bending force; and The second system point among the at least two system points, the second system point is located 13 mm proximal from the most distal end of the catheter system, wherein the second system point can be the same as or different from the proximal point, and the second system point has a second system bending force; Wherein, the difference between the second bending force and the first bending force divided by the distance between the distal point and the middle point is equal to the first flexural slope; Wherein, the difference between the third bending force and the second bending force divided by the distance between the middle point and the proximal point is equal to the second flexural slope; Wherein, the average of the first flexural slope and the second flexural slope defines the average tip flexural slope; Wherein, the difference between the first system bending force and the second system bending force divided by the distance between the first system point and the second system point is equal to the third flexural slope; and Wherein, the ratio of the third flexural slope to the average tip flexural slope is less than 25.

15. The catheter system according to claim 14, wherein, The length of the tip is at least 1 cm to 4 cm.

16. The catheter system according to claim 15, wherein, The ratio of the third bending force of the proximal point to the first bending force of the distal point is at least 2.

17. The catheter system according to claim 14, wherein, The ratio of the first system bending force to the first bending force of the distal point is at least 2.

18. The catheter system according to claim 14, wherein, The tubular portion of the catheter propulsion element has a radiopaque marker band, the radiopaque marker band is embedded within the wall of the tubular portion or located above the wall of the tubular portion, and the radiopaque marker band is located at the fitting point.

19. The catheter system according to claim 14, wherein, The outer diameter of the tubular portion extends along the length of the tubular portion, and the length is at least 5 cm to 10 cm, wherein the fitting point is positioned along at least a part of the length.

20. The catheter system according to claim 19, wherein, The outer diameter is substantially uniform along the length.

21. The catheter system according to claim 20, wherein, The outer diameter is substantially non-uniform along the length.

22. A catheter system, the system comprising: A catheter, including a lumen and a distal end having an opening from the lumen; And A catheter propulsion element, including: A tubular portion having an inner diameter and an outer diameter; and A tapered tip portion located distally of the tubular portion, wherein an alignment point of the catheter advancement element is proximal to the tapered tip portion; wherein the catheter system has an assembled configuration, characterized in that: a) The catheter advancement element is located within the lumen of the catheter, wherein the alignment point of the catheter advancement element is substantially aligned with the distal end of the catheter, and b) wherein, in the assembled configuration, the tapered tip portion has at least three points spaced along the length of the tapered tip portion, the at least three points including: A distal point of the at least three points, the distal point being located 5 mm proximal from the most distal end of the catheter advancement element, the distal point having a first bending force; An intermediate point of the at least three points, the intermediate point being located 20 mm proximal from the most distal end of the catheter advancement element, the intermediate point having a second bending force; and A proximal point of the at least three points, the proximal point being located 25 mm proximal from the most distal end of the catheter advancement element, the proximal point having a third bending force; and c) wherein the catheter system has at least two system points along the length of the catheter system, the at least two system points including: A first system point of the at least two system points, the first system point being located 33 mm proximal from the most distal end of the catheter system, the first system point having a first system bending force; and A second system point of the at least two system points, the second system point being located 25 mm proximal from the most distal end of the catheter system, wherein the second system point can be the same as or different from the proximal point, the second system point having a second system bending force; wherein the difference between the second bending force and the first bending force divided by the distance between the distal point and the intermediate point equals a first flexural slope; wherein the difference between the third bending force and the second bending force divided by the distance between the intermediate point and the proximal point equals a second flexural slope; wherein the average of the first flexural slope and the second flexural slope defines an average tip portion flexural slope; wherein the difference between the first system bending force and the second system bending force divided by the distance between the first system point and the second system point equals a third flexural slope; and wherein the ratio of the third flexural slope to the average tip portion flexural slope is less than 25.

23. A catheter system, the system comprising: A catheter including a lumen and a distal end having an opening from the lumen, the lumen having an inner diameter of at least about 0.052” at the distal end; and A catheter advancement element, comprising: A tubular portion having a single lumen, the single lumen having an inner diameter of at least 0.014” to 0.024” and an outer diameter between 0.048” and 0.080”, sized to substantially fill the lumen of the catheter; At least one radiopaque marker located near the attachment point; A tubular polymer tip portion located distally of the attachment point, wherein the tip portion tapers along the length of the tip portion, the length being at least 1 centimeter to 4 centimeters; and A proximal hub is coupled to the proximal end of the catheter advancement element at a distance from the distal end of the catheter advancement element, and the proximal hub is sized to remain outside of the catheter lumen. Wherein, the bending force of the catheter advancement element increases along the length of the tip portion to the at least one radiopaque marker located near the engagement point and then decreases near the engagement point. Wherein, the catheter system has an assembled configuration, characterized in that the catheter advancement element is located within the lumen of the catheter, wherein the engagement point of the tubular portion is substantially aligned with the distal end of the catheter, and Wherein, in the assembled configuration, the transition of the flexibility of the catheter system from the distal end of the tip portion to a point proximal to the distal end of the catheter is defined by a substantially constant slope that does not include a step increase.

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