Systems, catheters and catheter advancement devices for performing medical procedures in intracranial vessels

Abstract

A system, catheter, and catheter advancement device for performing a medical procedure in an intracranial vessel are described. A catheter advancement device includes a flexible, elongated body having a proximal portion coupled to a proximal region of the flexible, elongated body and extending proximally to a proximal end of a catheter advancement element. The hardness of the flexible, elongated body transitions proximally toward increasingly harder materials until the proximal end, forming a first plurality of material transitions. At least a portion of the flexible, elongated body is formed from a plurality of layers including a reinforcement layer. The outer diameter of the flexible, elongated body is sized to be coaxially positioned within the lumen of the catheter so that the distal tip of the flexible, elongated body extends distally beyond the distal end of the catheter to assist in delivery of the catheter to the intracranial vessel.

Description

[0001] This application is a divisional application of the PCT international invention patent application with application number 201880016784.3, application date January 9, 2018, and invention name “Suction catheter system and method of use”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority under 35 U.S.C. §119(e) to co-pending U.S. Provisional Patent Application No. 62 / 444,584, filed on January 10, 2017, and co-pending U.S. Provisional Patent Application No. 62 / 607,510, filed on December 19, 2017. The disclosures of the provisional applications are incorporated by reference in their entirety. Technical Field

[0004] The present technology relates generally to medical devices and methods and, more particularly, to systems, catheters, and catheter advancement devices for performing medical procedures in intracranial vessels. Background Art

[0005] Acute ischemic stroke (AIS) usually occurs when an artery to the brain becomes blocked, which prevents fresh oxygenated blood from being delivered to the brain from the heart and lungs. These blockages are usually caused by a blood clot or embolus that gets stuck in an artery and blocks the artery that supplies an area of ​​brain tissue. If an artery is blocked, post-ischemic damage ensues, and brain cells may stop working. Furthermore, if the artery remains blocked for more than a few minutes, brain cells may die, which leads to permanent neurological deficits or death. Therefore, immediate treatment is critical.

[0006] There are two main therapies used to treat ischemic stroke: thrombolytic therapy and endovascular therapy. The most common treatment used to restore flow or reperfuse the stroke area is the use of intravenous (IV) thrombolytic therapy. The time period for thrombolytic therapy is within 3 hours of symptom onset for IV infusion (4.5 hours for selected patients) or within 6 hours for fixed-point intra-arterial infusion. Giving therapy later has not been shown to be beneficial and may expose the patient to a greater risk of bleeding due to the thrombolytic effect. Endovascular therapy most often uses a set of tools to mechanically remove the embolus, and we do not use thrombolytic therapy.

[0007] The entire spectrum of endovascular treatments includes mechanical embolectomy, which uses a retractable structure, such as a coil tip retractable stent (also known as a "stent retriever" or STENTRIEVER), a wire mesh stent, or a laser cut stent with struts that can be opened within a clot in the brain anatomy to allow the clot to engage with the stent struts, create a channel in the embolus to restore a certain amount of blood flow, and then retract the retractable structure by pulling it out of the anatomy together with aspiration techniques. Other endovascular techniques for mechanically removing AIS-associated emboli include manual aspiration thrombectomy (MAT) (also known as the "ADAPT" technique). ADAPT / MAT is an endovascular procedure in which a large bore catheter is inserted through the transfemoral artery and manipulated through the complex anatomy to the level of the embolus, which may be located in the extracranial carotid artery, vertebral artery, or intracranial artery. Aspiration techniques can be used to remove emboli with the aid of a large bore catheter. Another endovascular procedure is Stentriever-mediated manual aspiration thrombectomy (SMAT) (similar to the Stentriever-assisted "Solumbra" technique). Like MAT, SMAT involves accessing the embolus via the femoral artery. However, after access is achieved, a retractable structure is used to pull the embolus back into the large-bore catheter.

[0008] In order to enter the brain anatomical structure, a guide catheter or guide sheath is used to guide the interventional device from the arterial access site (usually the femoral artery) to the target anatomical structure. The length of the guide is determined by the distance between the access site and the desired position of the guide far tip. Interventional devices such as guide wires, microcatheters, and intermediate catheters used for sub-selective guidance and suction are inserted and advanced to the target site with the help of guides. Typically, the device is used in a coaxial style, that is, the guide wire inside the microcatheter inside the intermediate catheter is advanced to the target site as a component in a step-by-step manner, and the most non-traumatic element inside is first advanced to the distal end and provides support for the advancement of other 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 from the distal end.

[0009] Typical triaxial systems (e.g., for aspiration or delivery of stent retrievers and other interventional devices) require an overlapping series of catheters, each with its own rotary hemostatic valve (RHV) on the proximal end. For example, a guidewire can be inserted with the aid of a Penumbra Velocity microcatheter having a first proximal RHV, which can be inserted with the aid of a Penumbra ACE68 having a second proximal RHV, which can be inserted with the aid of a Penumbra NeuronMAX 088 access catheter having a third proximal RHV positioned in the high carotid artery via a femoral introducer. Maintaining a coaxial relationship between these catheters can be technically challenging. The three RHVs must be constantly adjusted with two hands or, more commonly, four hands (i.e., two operators). Further, the working area of ​​a typical triaxial system for aspiration and / or intracranial device delivery may require a 3-5 foot working area at the base of the operating table.

[0010] The time required to access the occlusion site and even partially restore flow to the vessel is critical in determining the successful outcome of such surgery. Similarly, the occurrence of distal emboli during surgery and potential negative neurological effects and surgical complications such as perforation and intracerebral hemorrhage are limitations to surgical success. A system of devices and methods is needed that allow rapid access, optimized catheter aspiration, and treatment to fully restore flow to an obstructed cerebral vessel. Summary of the invention

[0011] In aspect, an intravascular catheter advancement device for facilitating intraluminal medical procedures within a neurovascular vessel is described. The catheter advancement device includes: a flexible, elongated body having a proximal region, an outer diameter, a tapered distal tip, a distal opening, and a single lumen extending longitudinally through the flexible, elongated body to the distal opening; and a proximal portion coupled to the proximal region of the flexible, elongated body. The proximal portion extends proximally to the most proximal end of the catheter advancement element. The hardness of the flexible, elongated body transitions proximally toward increasingly harder materials until the proximal end, forming a first plurality of material transitions. At least a portion of the flexible, elongated body is formed by a plurality of layers including a reinforcement layer. The outer diameter of the flexible, elongated body is sized to be coaxially positioned within the lumen of the catheter so that the distal tip of the flexible, elongated body extends distally beyond the distal end of the catheter to assist in delivery of the catheter to the intracranial vessel.

[0012] The reinforcement layer can be a webbing. The webbing can extend from the proximal region of the flexible elongated body and terminate at a point proximal to the distal tip. The point can be between 4 cm and 15 cm from the farthest end of the flexible elongated body. The plurality of layers can also include a first polymer material layer and a second polymer material layer. The webbing can be positioned between the first polymer material layer and the second polymer material layer. The proximal portion can be a hypotube having a distal end coupled to the flexible elongated body. The webbing can be positioned between the first polymer material layer and the second polymer material layer and positioned above the distal end of the hypotube.

[0013] The distal tip portion may include a material having a material hardness of no more than 35D. The proximal region of the elongated body may include a material having a material hardness between 55D and 72D. The elongated body may include a first section including a distal tip portion having a hardness of no more than 35D. The elongated body may include a second section located at the proximal end of the first section having a hardness of no more than 55D. The elongated body may include a third section located at the proximal end of the second section having a hardness of no more than 72D. The proximal portion may be coupled to the elongated body within the third section. The first section may not be reinforced, and the third section may be reinforced. The second section may be at least partially reinforced. The reinforcement webbing may extend through at least the third section. The first section, the second section, and the third section may be combined to form an insertion length of the elongated body. The first section may have a length of about 4cm to about 12.5cm. The second section may have a length of about 5cm to about 8cm. The third section may have a length of about 25cm to about 35cm.

[0014] The system may also include a catheter having a lumen and a distal end. The catheter may include a flexible distal lumen portion having a proximal end, a proximal region, and a proximal opening. The lumen may extend between the proximal end and the distal end. The catheter may also include a proximal extension extending from an attachment point adjacent to the proximal opening to the proximal end. The proximal extension may be less flexible than the flexible distal lumen portion and may be configured to control the movement of the catheter. The proximal extension may have an outer diameter at the attachment point that is smaller than the outer diameter of the distal lumen portion at the attachment point. The material hardness of the flexible distal lumen portion may transition toward a harder and harder material toward the proximal end until the proximal extension. The flexible distal lumen portion may include a second plurality of material transitions. The flexible, slender body can be coaxially positioned within the lumen of the catheter such that the distal tip portion of the flexible, slender body extends distally beyond the distal end of the catheter, such that a first plurality of material transitions of the flexible, slender body are staggered relative to a second plurality of material transitions of the flexible distal lumen portion and do not overlap with the second plurality of material transitions.

[0015] The catheter may be wrapped with a device coaxially positioned within the lumen of the catheter such that the proximal end of the flexible elongate body is locked with the proximal extension of the catheter.At least a portion of the proximal extension of the catheter may be color coded.

[0016] The single lumen of the flexible, elongated body can be sized to accommodate a guide wire. The flexible, elongated body can include a proximal opening sized to accommodate a guide wire. The proximal opening can be located in the proximal region of the flexible, elongated body. The proximal opening can pass through the sidewall of the flexible, elongated body and be located at a distance distal to the proximal portion coupled to the proximal region. The distance can be about 10 cm from the distal tip to about 20 cm from the distal tip. The proximal portion can have an outer diameter smaller than the outer diameter of the flexible, elongated body. The proximal portion can be a hypotube. The device can be configured to advance together with the catheter after the distal end of the catheter is at the distal end of the petrous portion of the internal carotid artery.

[0017] In a related aspect, a method for performing a medical procedure in a cerebral blood vessel of a patient is disclosed, the method comprising the following steps: inserting an assembled coaxial catheter system into a blood vessel of the patient. The assembled coaxial catheter system includes a catheter and a catheter advancement element. The catheter includes: a flexible distal lumen portion having a proximal end, a proximal region, a proximal opening, a distal end, and a lumen extending between the proximal end and the distal end; and a proximal extension portion extending proximally from an attachment point adjacent to the proximal opening. The proximal extension portion is less flexible than the flexible distal lumen portion and is configured to control movement of the catheter. The proximal extension portion has an outer diameter at the attachment point that is smaller than the outer diameter of the distal lumen portion at the attachment point. The catheter advancement element includes: a flexible, elongated body having a proximal region, an outer diameter, a tapered distal tip, a distal opening, and a single lumen extending longitudinally through the flexible, elongated body to the distal opening; and a proximal portion extending proximally from the proximal region to the proximal-most end of the catheter advancement element. When assembled, the catheter advancement element extends through the catheter lumen, and the tapered distal tip extends distally of the distal end of the distal lumen portion. The method also includes the steps of advancing the assembled catheter system until the distal end of the distal lumen portion reaches a target site within a cerebral vessel, and the attachment point between the distal lumen portion and the proximal extension portion is positioned proximal to a brachiocephalic artery exit point in the aortic arch. The method also includes the steps of removing the catheter advancement element from the lumen of the catheter; and removing the occlusive material while applying negative pressure to the lumen of the catheter.

[0018] When the attachment point is positioned proximal to the brachiocephalic artery lead-out point within the aortic arch, the distal end of the distal lumen portion can be positioned distal to the carotid siphon portion. The distal lumen portion can have a length between 35 cm and 60 cm. The proximal portion of the catheter advancement element can be coupled to the proximal region of the flexible, slender body at the attachment point, and the proximal portion extends proximally from the attachment point to the nearest end of the catheter advancement element. The proximal portion can have a single lumen extending through the entire length of the proximal portion, and the proximal portion is connected to the single lumen of the slender body. The slender body can have a length sufficient to allow the attachment point between the slender body and the proximal portion to remain within the aortic arch or proximal to the aortic arch when assembled with the catheter. The distal end of the catheter can be positioned near the target site within the cerebral blood vessels.

[0019] The assembled catheter system can be pre-wrapped with a catheter advancement element coaxially positioned within the lumen of the distal lumen portion so that the proximal end of the flexible elongated body is locked with the proximal extension of the catheter. At least a portion of the proximal extension of the catheter can be color-coded. A single lumen of the flexible elongated body can be sized to accommodate a guidewire. The flexible elongated body can include a proximal opening sized to accommodate a guidewire. The proximal opening can be located in the proximal region of the flexible elongated body. The proximal opening can pass through the sidewall of the flexible elongated body and can be located at a distance distal to the proximal end coupled to the proximal region. The distance can be about 10 cm from the distal tip to about 20 cm from the distal tip. The hardness of the flexible elongated body can transition toward increasingly harder materials toward the proximal end until the proximal end, forming a first plurality of material transitions. At least a portion of the flexible elongated body can be formed by a plurality of layers including a reinforcement layer. The reinforcement layer can be a webbing. The webbing can extend from the proximal region of the flexible elongated body and terminate at a point proximal to the distal tip. The point may be located between 4 cm and 15 cm from the farthest end of the flexible elongated body. The plurality of layers may further include a first polymer material layer and a second polymer material layer. The webbing may be positioned between the first polymer material layer and the second polymer material layer. The proximal end may be a hypotube having a distal end coupled to the flexible elongated body. The webbing positioned between the first polymer material layer and the second polymer material layer is positioned above the distal end of the hypotube.

[0020] The distal tip portion may include a material having a material hardness of no more than 35D. The proximal region of the elongated body may include a material having a material hardness between 55D and 72D. The elongated body may include a first section including a distal tip portion having a hardness of no more than 35D. The elongated body may include a second section located at the proximal end of the first section having a hardness of no more than 55D. The elongated body may include a third section located at the proximal end of the second section having a hardness of no more than 72D. The proximal portion may be coupled to the elongated body within the third section. The first section may not be reinforced, and the third section may be reinforced. The second section may be at least partially reinforced. The reinforced webbing may extend through at least the third section. The first section, the second section, and the third section may be combined to form an insertion length of the elongated body. The first section may have a length of about 4cm to about 12.5cm. The second section may have a length of about 5cm to about 8cm. The third section may have a length of about 25cm to about 35cm. The material hardness of the flexible distal lumen portion may transition toward increasingly harder materials toward the proximal end until the proximal extension. The flexible distal lumen portion may include a second plurality of material transitions. The flexible elongated body may be coaxially positioned within the lumen of the catheter such that the distal tip portion of the flexible elongated body extends distally beyond the distal end of the catheter such that the first plurality of material transitions of the flexible elongated body are staggered relative to, and do not overlap, the second plurality of material transitions of the flexible distal lumen portion.

[0021] In a related aspect, a method for performing a medical procedure in a cerebral blood vessel of a patient is described, the method comprising the steps of inserting a guide sheath into the blood vessel. The guide sheath includes a lumen extending between a proximal region and a distal region of the guide sheath, the distal region of the guide sheath having an opening in communication with the lumen of the guide sheath. The method comprises the steps of positioning the guide sheath so that the distal region of the guide sheath is positioned within the plane of at least the common carotid artery. The method comprises the steps of inserting an intermediate catheter through the lumen of the guide sheath. The intermediate catheter includes a lumen and a distal opening at the distal end of the intermediate catheter. The method comprises the steps of advancing the intermediate catheter so that the distal end of the intermediate catheter advances through the opening of the guide sheath and beyond the distal region of the guide sheath. The method comprises the steps of inserting a distal access catheter through the lumen of the intermediate catheter. The distal access catheter includes: a flexible distal lumen portion having a proximal end, a proximal region, a proximal opening, a distal end, and a lumen extending between the proximal end and the distal end; and a proximal extension portion extending proximally from an attachment point adjacent to the proximal opening. The proximal extension portion is less flexible than the flexible distal lumen portion and is configured to control movement of the catheter. The proximal extension portion has an outer diameter at the attachment point that is smaller than the outer diameter of the flexible distal lumen portion at the attachment point. The method also includes the following steps: advancing the distal access catheter so that the distal end of the flexible distal lumen portion advances through the distal opening of the intermediate catheter and beyond the distal end of the intermediate catheter.

[0022] The distal region of the guide sheath may include an inflatable occlusion balloon. The method may further include the steps of inflating the occlusion balloon to occlude antegrade flow through the common carotid artery. The distal region of the guide sheath may have an unlined, unreinforced region that is configured to seal to the outer surface of the intermediate catheter. Prior to the advancement step, the distal access catheter may be assembled with a catheter advancement element to form an assembled coaxial catheter system. The catheter advancement element includes: a flexible, elongated body having a proximal region, an outer diameter, a tapered distal tip, a distal opening, and a single lumen extending longitudinally through the flexible, elongated body to the distal opening; and a proximal portion that extends proximally from the proximal region to the most proximal end of the catheter advancement element.

[0023] When assembled, the catheter advancement element can extend through the lumen of the distal lumen portion, and the tapered distal tip portion can extend distal to the distal end of the distal lumen portion. The method can also include the steps of advancing the assembled coaxial catheter system until the distal end of the distal lumen portion reaches a target site within a cerebral vessel and the attachment point between the distal lumen portion and the proximal extension portion is positioned proximal to a brachiocephalic artery exit point in the aortic arch. The method can also include the steps of removing the catheter advancement element from the lumen of the catheter; and removing the occlusive material while applying negative pressure to the lumen of the catheter.

[0024] The assembled catheter system can be pre-wrapped with a catheter advancement element, which is coaxially positioned in the lumen of the distal lumen portion so that the proximal portion of the flexible elongated body is locked with the proximal extension of the catheter. At least one of the intermediate catheter and the distal entry catheter may also include a tab to prevent excessive insertion of the catheter relative to the lumen through which the catheter extends. At least one of the intermediate catheter and the distal entry catheter may also include a distinguishable color-coded element. The single lumen of the flexible elongated body can be sized to accommodate a guide wire. The flexible elongated body can include a proximal opening sized to accommodate a guide wire. The proximal opening can be located in the proximal region of the flexible elongated body. The proximal opening can pass through the sidewall of the flexible elongated body and can be located at a distance to the distal end of the proximal portion coupled to the proximal region. The distance can be about 10 cm from the distal tip to about 20 cm from the distal tip.

[0025] Prior to the advancement step, the intermediate catheter can be assembled with the catheter advancement element to form an assembled coaxial catheter system. The catheter advancement element may include: a flexible, elongated body having a proximal region, an outer diameter, a tapered distal tip, a distal opening, and a single lumen extending longitudinally through the flexible, elongated body to the distal opening; and a proximal portion extending proximally from the proximal region to the nearest end of the catheter advancement element. When assembled, the catheter advancement element may extend through the lumen of the intermediate catheter, and the tapered distal tip may extend distally to the distal end of the distal end of the intermediate catheter. The intermediate catheter may include a flexible distal lumen portion and a proximal extension portion, which extends proximally from an attachment point adjacent to the proximal opening in the flexible distal lumen portion. The proximal extension portion may be less flexible than the flexible distal lumen portion of the intermediate catheter and have an outer diameter smaller than the outer diameter of the proximal elongated body.

[0026] In some variations, one or more of the following may be optionally included in the above methods, devices, apparatuses, and systems in any feasible combination. More details of the apparatus, system, and method are set forth in the accompanying drawings and the following description. Other features and advantages will be apparent from the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] These and other aspects will now be described in detail with reference to the following drawings. In general, the drawings are not to scale, absolutely or comparatively, but are intended to be illustrative. Moreover, the relative placement of features and elements may be modified for purposes of illustration clarity.

[0028] Figure 1A to Figure 1B The course of the terminal end of the internal carotid artery up to the cerebral vessels is illustrated;

[0029] Figure 1C The location of the brachiocephalic artery exit point from the aortic arch is illustrated;

[0030] Figure 2A is an exploded view of an embodiment of an aspiration catheter system;

[0031] Figure 2B yes Figure 2A Assembly diagram of the system;

[0032] Figure 2C It is intercepted at circle CC Figure 2A Detailed diagram of

[0033] Figure 2D An embodiment of an arterial access device having a distal occlusion balloon is illustrated;

[0034] Figure 3 is a side view of an embodiment of a catheter;

[0035] Figure 4Ais a cross-sectional view of a first embodiment of a proximal extension of a catheter;

[0036] Figure 4B is a cross-sectional view of another embodiment of a proximal extension of a catheter;

[0037] Figure 4C It is in the working lumen of the access sheath. Figure 4A a cross-sectional view of the proximal extension of;

[0038] Figure 4D It is in the working lumen of the access sheath. Figure 4B a cross-sectional view of a proximal extension of the access sheath having a catheter advancing element extending therethrough;

[0039] Figure 4E It is relatively Figure 4D The working lumen of the access sheath Figure 4A The proximal extension of Figure 4B A schematic cross-sectional view of the surface area of ​​the proximal extension of the embodiment;

[0040] Figures 4F to 4G are schematic cross-sectional views comparing the trapezoidal and D-shaped proximal extensions, respectively, relative to the working lumen of the entry sheath;

[0041] Figure 5A is a side view of an embodiment of a catheter;

[0042] Figure 5B yes Figure 5A A top plan view of the catheter;

[0043] Figure 5C It is along Figure 5B A cross-sectional view of the catheter taken along line CC;

[0044] Figure 5D It is along Figure 5B A cross-sectional view of the catheter taken along line DD;

[0045] FIG. 5E to FIG. 5F yes Figure 5A A partial stereoscopic view of a catheter;

[0046] Fig. 6A is a side view of an embodiment of a catheter;

[0047] Figure 6B yes Fig. 6A A top plan view of the catheter;

[0048] Figure 6C It is along Figure 6B A cross-sectional view of the catheter taken along line CC;

[0049] Fig.6D It is along Figure 6BA cross-sectional view of the catheter taken along line DD;

[0050] FIG. 6E to FIG. 6F yes Fig. 6A A partial stereoscopic view of a catheter;

[0051] Fig. 7A is a side view of an embodiment of a catheter advancement element;

[0052] Figure 7B yes Fig. 7A A cross-sectional view of a catheter advancement element;

[0053] Figure 7C It is taken along circle CC Figure 7B Detailed diagram of

[0054] Fig.7D is a side view of another embodiment of a catheter advancement element;

[0055] Fig. 7E yes Fig.7D A cross-sectional view of an embodiment of a proximal portion of a catheter advancement element;

[0056] FIG. 7F to FIG. 7J is used to couple to Fig. 7E Various views of an embodiment of a proximal hub of the proximal portion are shown;

[0057] Fig. 8A is a side view of an embodiment of a catheter;

[0058] Figure 8B yes Fig. 8A A schematic cross-sectional view of a distal end region of a catheter;

[0059] Figure 8C yes Fig. 8A A schematic cross-sectional view of a distal region of a catheter;

[0060] 9A to 9C are various views of the proximal extension connector;

[0061] Fig. 10A is a schematic cross-sectional view of an embodiment of a catheter advancement element;

[0062] Fig. 10B yes Fig. 10A A schematic cross-sectional view of a distal region of a catheter advancement element;

[0063] Fig. 10C yes Fig. 10A A schematic cross-sectional view of a middle region of a catheter advancement element;

[0064] Fig.11is a schematic diagram of an embodiment of a catheter aligned with an embodiment of a catheter advancement element illustrating staggered material transitions; and

[0065] Fig.12 It is a tear-off disc coupler.

[0066] It should be understood that the drawings are only examples and are not intended to be to scale. It should be understood that the devices described herein may include features that are not necessarily depicted in each of the drawings. DETAILED DESCRIPTION

[0067] Navigating the carotid anatomy to treat various neurovascular pathologies at the level of the cerebral arteries, such as acute ischemic stroke (AIS), requires a catheter system with excellent flexibility and deliverability. The internal carotid artery (ICA) originates from the bifurcation of the common carotid artery (CCA) at the level of the intervertebral disc between the C3 and C4 vertebrae. Figure 1A As shown, the course of ICA is divided into four parts—cervical Cr, petrous Pt, cavernous Cv and brain Cb parts. In the anterior circulation, the consistently tortuous terminal carotid artery is locked into its position by a bone element. The cervical carotid artery Cr enters the petrous bone and is locked into a set of turns wrapped in the bone. The cavernous carotid artery is an artery that passes through the venous bed (cavernous sinus) and is locked while being flexible as it leaves the cavernous sinus by another bone element, which surrounds and is fixed to the entrance in the cranial cavity. Due to these bone fixation points, the petrous and cavernous carotid arteries (Pt and Cv) and above are relatively consistent in their tortuosity. The carotid siphon CS is the S-shaped part of the terminal ICA. The carotid siphon CS starts at the back bend of the cavernous ICA and ends at the ICA bifurcation to the anterior cerebral artery ACA and the middle cerebral artery MCA. The ophthalmic artery originates from the brain ICA, which represents the common point where the catheter hangs when entering the anterior circulation. These points at which the catheter hangs up can significantly increase the amount of time required to restore blood perfusion to the brain, a drawback with serious consequences in the treatment of AIS.

[0068] As age increases, large blood vessels often become larger and longer. Fixed at the proximal and distal ends, the internal carotid artery often becomes tortuous as age increases. The common carotid artery CCA is relatively fixed in the thoracic cavity as it leaves the neck region by the clavicle. The external and internal carotid arteries EC A, ICA are not fixed relative to the common carotid artery CCA, so as the entire carotid system is extended, they form tortuosity as age increases. This may cause them to stretch and form kinks and tortuosity, or in the worst case, form a complete ring or so-called "neck ring". If the catheter used to cross these kinks or tortuosity areas is too rigid or inflexible, these areas may be subjected to the straightening that may cause the blood vessel to entangle or cause the concentrated kinks and folding of the blood vessel "barbershop pole (barbershop pole)". The extreme tortuosity of these types may also significantly increase the amount of time required for blood perfusion to the brain, particularly in the elderly population. In some cases, the torsion of the blood vessel on itself or if the untwisted artery kinks, the normal antegrade flow may be reduced to stillness, which produces ischemia. Managing dekinking or delooping of vessels such as the ICA in the neck may also increase the time it takes to perform the procedure.

[0069] A major disadvantage of current catheter systems used for stroke intervention procedures is the amount of time required to restore blood perfusion to the brain, including the time spent accessing the occluded site in the cerebral artery and the time spent completely removing the occlusion in the artery. Because it is often the case that more than one attempt must be made to completely remove the occlusion, reducing the number of attempts and reducing the time required to exchange devices for additional attempts are important factors in minimizing the total time. In addition, each attempt is associated with potential surgical risks due to device advancement in fragile cerebral vessels. Another limitation is the need for multiple operators to deliver and effectively manipulate long triaxial systems with multiple RHVs that are typically used with traditional guide and distal access catheters.

[0070] A catheter system for treating various neurovascular pathologies, such as acute ischemic stroke (AIS), is described herein. The system described herein provides rapid and simple single operator access to a distal target anatomical structure, particularly the tortuous anatomical structure of cerebral blood vessels at a single manipulation point. The medical methods, devices, and systems described herein allow navigation of complex tortuous anatomical structures to perform rapid and safe aspiration and removal of cerebral occlusions in order to treat acute ischemic stroke. The medical methods, devices, and systems described herein can also be used to deliver intracranial medical devices with or without aspiration for removing cerebral occlusions in the treatment of acute ischemic stroke. The system described herein can be particularly useful for the treatment of AIS, whether the user intends to perform stent retractor delivery alone, aspiration alone, or a combination of aspiration and stent retractor delivery as a first-line treatment for AIS. Further, the extreme flexibility and deliverability of the distal access catheter system described herein allow the catheter to take the shape of a tortuous anatomical structure, rather than applying a straightening force that creates a new anatomical structure. The distal access catheter system described herein can pass through a tortuous loop while maintaining the natural curve of the internal anatomical structure, which reduces the risk of vascular straightening. Thus, the distal access catheter system described herein can create a secure tract through the neurovascular system that maintains the natural tortuosity of the anatomy for passage of other catheters (e.g., interventional device delivery catheters). The catheters that pass through the tract do not need to have the same degree of flexibility and deliverability such that if they were delivered directly to the same anatomy rather than through the tract, straightening, kinking, or folding of the anterior circulation would result.

[0071] It should be understood that, although some embodiments are described herein, particularly with respect to the delivery of access to neurovascular anatomical structures or therapeutic devices, the systems and methods described herein should not be limited thereto and may also be applicable to other uses. For example, the catheter system described herein may be used to deliver a working device to a target vessel of a coronary artery anatomical structure or other vascular anatomical structure. It should also be understood that, where the phrase "suction catheter" is used herein, such a catheter may also be used for purposes other than suction, such as delivering fluid to a treatment site or as a support catheter or distal access catheter that provides a conduit for facilitating and guiding the delivery or exchange of other devices (such as guidewires or interventional devices, such as stent retractors). Alternatively, the access system described herein may also be used to access other parts of the body outside of a blood vessel. Similarly, where the working device is described as an expandable brain treatment device, a stent retractor, or a self-expanding stent, the delivery system described herein may be used to deliver other interventional devices.

[0072] Now referring to the accompanying drawings, FIG. 2A to FIG. 2BA system 100 is illustrated, which includes a device for accessing and removing a cerebral occlusion to treat acute ischemic stroke from an access site. The system 100 can be a single operator system so that the various components and systems can be delivered and used together by one operator using minimal hand movement. As will be described in more detail below, all wire and catheter manipulations can occur at or near a single rotary hemostatic valve (RHV) 434 or more than a single RHV co-located in the same device. The system 100 may include one or more of a catheter 200, a catheter advancement element 300, and an entry guide sheath 400, each of which will be described in more detail below. The catheter 200 is configured to be received by means of a guide sheath 400 and is designed to have superior delivery capabilities. The catheter 200 can be a rotating distal entry catheter coaxial with the lumen of the guide sheath 400, thereby providing a step of the inner diameter in the conduit. The catheter 200 can be delivered using a catheter advancement element 300 inserted through the lumen 223 of the catheter 200 to form a catheter delivery system 150. System 100 can be a distal access system that can produce a variable length from the entry point of a percutaneous arteriotomy (e.g., femoral artery) to the target control point of the distal catheter. Conventional distal access systems for stroke interventions typically include a long guide sheath or guide catheter placed in the groin with the help of a shorter "introducer" sheath (e.g., 11-30 cm in length). Long guide sheaths are typically positioned in the ICA to support neurovascular interventions including stroke thrombectomy. To increase support, these elements can be advanced all the way to the end of the bone petrosal, and rarely enter the cavernous or sellar or supraclinoid end d terminal ICA when possible. In order to reach the target in the M1 or M2 distribution for the ADAPT / MAT or Solumbra / SMAT methods, additional catheters are inserted with the help of long guide catheters. These catheters are typically large-caliber suction catheters, which can be 130 cm or longer in length. As will be described in more detail below, the distal access system 100 described here can be shorter, for example, only 115 cm in length. Additionally, a single operator can use the systems described herein by inserting them through a single rotary hemostasis valve (RHV) 434 on an introducer sheath 400 or more than one RHV (such as a dual-ended RHV) co-located in the same device. Thus, what was once a two-person procedure can be a one-person procedure.

[0073] Each of the various components of the various systems will now be described in greater detail.

[0074] Enter the introducer sheath

[0075] Refer again FIG. 2A to FIG. 2D, the distal access system 100 may include an access guide sheath 400 having a body 402, and a working lumen extending through the body 402 to a distal opening 408 of the distal region from a proximal hemostasis valve 434 coupled to a proximal region 403 of the body 402. The working lumen is configured to receive a catheter 200 therethrough so that the distal end of the catheter 200 can extend beyond the distal end of the sheath 400 through the distal opening 408. The guide sheath 400 can be used to deliver any of the catheters described herein and various working devices known in the art. For example, the working device can be configured to provide thrombosis treatment and can include large-bore catheters, aspiration thrombectomy, advanced catheters, wires, balloons, retractable structures (such as coil tip retractable stents "Stentriever"). The guide sheath 400 in combination with the catheter 200 can be used to apply distal suction, as will be described in more detail below.

[0076] 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 Cook SHUTTLE 6F (Cook Medical, Inc., Bloomington, Indiana), Terumo DESTINATION 6F (Terumo Europe NV), Cordis VISTABRITE TIP (Cordis, Inc., Hialeah, Florida), and Penumbra NEURON MAX 088 (Penumbra, Inc., Alameda, California), or similar commercially available guide sheaths. Typically, the French (F) scale is used here to describe sheath size. For example, where a sheath is described as 6F, it should be understood that the inner diameter of the sheath is capable of receiving a catheter having an outer diameter of 6F, which is approximately 1.98 mm or 0.078". Therefore, it should be understood that a catheter may be described herein as having a particular size of French to refer to the compatibility of its inner diameter to receive the outer diameter of another catheter. A catheter may also be described herein as having a particular size of French to refer to its outer diameter being compatible with another catheter having a particular inner diameter.

[0077] Refer again FIG. 2A to FIG. 2D, the catheter body 402 can extend from a proximal bifurcation or a rotary hemostatic valve (RHV) 434 at a proximal region 403 to a tip 406 at a 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. As described above, the working lumen can receive the catheter 200 and / or any of a variety of working devices for delivery to the target anatomical structure. The RHV 434 can be constructed of a thick-walled polymer tube or a reinforced polymer tube. The RHV 434 allows the device to be introduced into the blood vessel with the help of 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 integral with the guide sheath 400, or the guide sheath 400 can terminate on the proximal end of a female Luer adapter to which a separate hemostatic valve component (such as a passive sealing valve, a Tuohy-Borst valve, or a rotary hemostatic valve) can be attached. The RHV 434 may have an adjustable opening that opens large enough to allow removal of a device with an adhered clot on the tip without displacing the clot during removal at the RHV 434. Alternatively, the RHV 434 may be removable, such as when the device is removed from the sheath 400 to prevent displacement of a clot at the RHV 434. The RHV 434 may be a double RHV.

[0078] RHV 434 can form a Y-shaped connector on the proximal end 403 of sheath 400, so that the first port of RHV 434 can be used to insert the working catheter into the working lumen of sheath 400, and the second port to arm 412 can be used for another purpose. For example, a syringe or other device can be connected to arm 412 via connector 432 to deliver forward instillation, flushing line for contrast or saline injection through body 402 toward tip 406 and target anatomical structure. Arm 412 can also be connected to a large-caliber suction line and suction source (not shown), such as a syringe or pump, to draw suction with the help of the working lumen. Arm 412 can also allow the guide sheath 400 to be flushed with saline or radiopaque contrast during surgery. The working lumen can extend from the distal end to the working proximal port of the proximal region 403 of the catheter body 402.

[0079] The length of the catheter body 402 is configured to allow the distal tip 406 of the body 402 to be positioned in the internal carotid artery (ICA), for example, as far as the femoral approach, which has an additional length to provide adjustment when needed. 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, but it should be understood that the length of the body 402 can be longer, for example, up to about 100 cm or up to about 105 cm or up to about 117 cm in total. In an embodiment, the body 402 length is suitable for the transcarotid approach to the carotid bifurcation, in the range of 20-25 cm. In other embodiments, the body 402 length is suitable for the percutaneous transcarotid approach to the CCA or proximal ICA, and in the range of 10-15 cm. The body 402 is configured to assume and navigate the bend of the blood vessel without kinking, collapsing or causing vascular trauma, even when subjected to high suction force, for example.

[0080] The tip 406 of the guide sheath 400 can have an outer diameter that is the same or similar to the segment of the body 402 leading to the distal end. Therefore, the tip 406 can have a distal face that is orthogonal to the longitudinal axis passing through the body 402, and the distal face can have an outer diameter that is substantially equal to the cross-sectional outer dimension of the body 402. In an embodiment, the tip 406 includes a chamfer, a rounded corner, or a taper, which makes the distal face diameter slightly smaller than the cross-sectional dimension of the body 402. In other embodiments, the tip 406 can be an elongated tubular portion that extends at the distal end of the region of the body 402 with a uniform outer diameter, so that the elongated tubular portion has a reduced diameter compared to the uniform outer diameter of the body 402. Thus, the tip 406 can be elongated or can be more bluntly shaped. Therefore, the tip 406 can be configured to smoothly track through the blood vessel and / or expand the blood vessel restriction as it tracks through the blood vessel. The working lumen can have a distal end that forms a distal opening 408.

[0081] The guide sheath 400 may include a tip 406 that tapers from the section 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 about 0.110" to about 0.035", or from about 0.106" to about 0.035". The angle of the taper 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.

[0082] In an embodiment, the guide sheath 400 includes one or more radiopaque markers 411. The radiopaque markers 411 can be arranged near the distal tip 406. For example, a pair of radiopaque bands can be forged, painted, embedded or otherwise arranged in or on the body 402. In some embodiments, the radiopaque markers 411 include barium polymers, tungsten polymer mixtures, 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 guide 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 figure as rings around the circumference of one or more regions of the body 402. However, the markers 411 need not be rings and can have other shapes or produce various patterns that provide the operator with orientation related to the location of the distal opening 408 within the blood vessel. Thus, the operator can visualize the position of the distal opening 408 under fluoroscopy to confirm that the distal opening 408 points to the target anatomical structure to which the catheter 200 is to be delivered. For example, the radiopaque marker 411 allows the operator to rotate the body 402 of the guide sheath 400 at an anatomical entry point (e.g., the patient's groin) so that the distal opening is provided with access to the ICA by subsequent working devices (e.g., a catheter and wire that advances to the ICA). In some embodiments, the radiopaque marker 411 includes platinum, gold, tantalum, tungsten, or any other material visible under an X-ray fluoroscope. It should be understood that any of the various components of the system described herein can be incorporated into a radiopaque marker as described above.

[0083] In some embodiments, the guide sheath 400 can have similar performance characteristics to other sheaths used in carotid access and AIS surgery in terms of kink resistance, radiopacity, column strength, and flexibility. The liner can be constructed of a low-friction polymer, such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene), to provide a smooth surface for advancing the device with the aid of the inner lumen. The outer sheath material can provide mechanical integrity for the liner, and can be constructed of materials such as PEBAX, thermoplastic polyurethane, polyethylene, nylon, etc. A third layer can be incorporated, which can provide reinforcement between the liner and the outer sheath. The reinforcement layer can prevent the inner lumen of the body 402 from flattening or kinking, to allow unimpeded device navigation and suction or reverse flow through the bends in the blood vessel. The body 402 can be circumferentially enhanced. The reinforcement layer can be made of metal (such as stainless steel, nitinol, nitinol webbing, spiral ribbon, spiral wire, cut stainless steel, etc.) or a rigid polymer (such as PEEK). The reinforcement layer can be a structure such as a coil or a webbing, or a laser cut or machine cut tube for flexibility. In another embodiment, the reinforcement layer can be a cut hypotube, such as a nitinol hypotube or a cut rigid polymer, etc. The outer sheath of the body 402 can be formed by a material that is increasingly softer toward the distal end. For example, the proximal region of the body 402 can be formed by a material such as nylon, and the region of the body 402 at the distal end of the proximal region of the body 402 can have a hardness of 72D, while the more distal region can be increasingly flexible and formed by a material with a hardness of 55D, 45D, 35D extending toward the distal tip 406, which can be formed by a material having a hardness of no more than 35D and softer than 35D in some embodiments. The body 402 may include a hydrophilic coating.

[0084] The flexibility of the body 402 can vary over its length, with increased flexibility toward the distal portion of the body 402. The variability of flexibility can be achieved in various ways. For example, the outer sheath can vary in hardness and / or material at various segments. An outer sheath material of lower hardness can be used in the distal segment of the guide sheath compared to other segments of the guide sheath. Alternatively, the wall thickness of the sheath material can be reduced, and / or the density of the reinforcement layer can be changed to improve flexibility. For example, the pitch of the coil or webbing can be stretched, or the cutting pattern in the tube can be changed to be more flexible. Alternatively, the reinforcement structure or material can vary over the length of the elongated body 402. In another embodiment, there is a transition segment between the distal-most flexible segment and the proximal segment, and one or more segments of varying flexibility are between the distal-most segment and the rest of the elongated body 402. In this embodiment, the distal-most segment is about 2 cm to about 5 cm, the transition segment is about 2 cm to about 10 cm, and the proximal segment occupies the rest of the sheath length.

[0085] Sheaths 400 of different inner diameters can be used to receive catheters 200 of different outer diameters. In some embodiments, the working lumen of the first sheath 400 can have an inner diameter sized to receive a 6F catheter, and the working lumen of the second sheath 400 can have an inner diameter sized to receive an 8F catheter. In some embodiments, the distal region of the sheath 400 can have an inner diameter of about 0.087” to 0.088”. The sheath 400 can receive catheters having outer diameters adapted to these inner diameter sizes. It should be understood that the sheath 400 (and any of the various components used in combination with the sheath 400) can be an over-the-wire (OTW) or rapid exchange device, which will be described in more detail below.

[0086] As described above, the sheath 400 can include a body 402 formed of generally three layers, which include a lubricious liner, a reinforcement layer, and an outer sheath layer. The reinforcement layer can include a braid that provides good torsional flexibility, which is optionally overlaid with coils to provide good kink resistance. In sheaths where the reinforcement layer is only a braid, the polymer of the outer sheath layer can typically be of higher hardness and thicker to avoid kinking issues. The wall thickness of such a sheath woven only with a thicker polymer can be about 0.011”. The wall thickness of the sheath 400 described here with a braid overlaid with coils provides both torsional flexibility and kink resistance, and can have a generally thinner wall, e.g., a wall thickness of about 0.0085”. Thus, the proximal outer diameter can be reduced to about 0.107” outer diameter. Thereby, the sheath 400 is a high-performance sheath 400 that has good torque and kink resistance, and 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 sheath 400 can gradually step down to be thinner towards the distal end of the sheath compared to the proximal end.

[0087] The sheath 400 can include a distal tip 406 that is designed to provide a good seal with the outer diameter of a catheter extending through its working lumen. The distal tip 406 can be formed of a soft material that lacks both a liner and a reinforcement layer. The lubricious liner layer and the reinforcement layer can extend through most of the body 402 except for the length of the distal tip 406 (see Figure 2C). The length of this unlined, unreinforced 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 distal-most terminus of the sheath 400, leaving the last 3 mm of unlined soft material forming the distal tip 406. In some embodiments, the coils and webbing of the reinforcement layer can have their ends held in place by a radiopaque marker 411 (such as a marker band positioned near the distal-most terminus of the sheath 400). The lining layer 409 can extend at least a length, for example, about 1 mm in length, distal to the marker band 411 before terminating. The staggered termination of the wall layers can assist in the transition from the marker band 411 to the soft polymer material 407 of the distal tip 406. The soft polymer material 407 can extend beyond the length of the lining layer 409. The unlined soft material 407 forming the distal tip 406 can be a PEBAX material having a hardness of no more than about 40D, no more than about 35D, no more than about 62A, or no more than about 25D. The softness of the material and the length of the unlined distal tip 406 of the sheath 400 can vary. Typically, the material is soft enough to be compressed downwardly to the outer diameter of the catheter 200 extending through the lumen of the sheath 400, such as when negative pressure is applied by means of the lumen. The length of the unlined unreinforced region 407 of the distal tip 406 is long enough to provide a good seal, but not long enough to cause the following problems: having accordion folds or folds between the sheath 400 and the catheter 200 during relative sliding, which may block the sheath lumen, or negatively affect the slidability of the catheter 200 in the sheath lumen.

[0088] The distal tip 406 can have an inner diameter that approximates 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 depending on what size catheter is to be used. For example, when the outer diameter of the catheter near the proximal end is approximately 0.101", the inner diameter of the sheath at the distal tip 406 can be approximately 0.106", so that the difference in diameter is approximately 0.005". When a vacuum is applied, the soft, unlined and unreinforced distal tip 406 can move to eliminate this 0.005" gap and compress downward onto the outer diameter of the catheter 200 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 approximately 0.002"-0.006". The inner diameter of the distal tip 406 can also be tapered so that the inner diameter at the distal-most terminus 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 formed so that the wall is inclined at a certain angle relative to the central axis of the sheath 400, such as approximately 60 degrees.

[0089] In some cases, it is desirable that the sheath body 402 also be able to occlude the artery in which it is located, for example, during surgery where distal emboli may occur. Occluding the artery stops antegrade blood flow, thereby reducing the risk of distal emboli, which may cause neurological symptoms such as TIA or stroke. Figure 2D An arterial access device or sheath 400 is shown having a distal occlusion balloon 440 that, when inflated, occludes the artery at the location of the sheath distal tip 406. At any point in the procedure, for example, during removal of the occlusion by suction and / or delivery of a stentriever or other interventional device, the occlusion balloon 440 can be inflated to occlude the vessel to reduce the risk of distal emboli to the cerebral vessels. The sheath 400 can include an inflation lumen in addition to the working lumen of the sheath 400, which is configured to deliver a fluid for inflating the occlusion balloon 440. The inflation lumen can fluidly connect the balloon 440 to an arm 412, such as on a proximal adapter. When vascular occlusion is desired, the arm 412 can be attached to an inflation device, such as a syringe, to inflate the balloon 440 with a fluid. The arm 412 can be connected to a passive or active suction source to further reduce the risk of distal emboli.

[0090] According to some embodiments, the length of the guide sheath 400 is long enough to enter the target anatomical structure and leave the arterial access site with the additional length outside the patient's body for adjustment. For example, the guide sheath 400 (whether or not with the distal occlusion balloon 440) can be long enough to enter the petrous ICA from the femoral artery, so that the additional length can still be used for adjustment. The guide sheath 400 can be of various sizes to accept various working devices and can adapt to the operator's preferences. For example, current MAT and SMAT techniques describe delivering an aspiration catheter with an inner diameter of 0.054"-0.072" to the embolus during AIS. Therefore, the working lumen of the guide sheath 400 can be constructed to receive the catheter 200 and other catheters or working devices known in the art. For example, the working lumen can have an inner diameter that is sized to accommodate at least a 6 French catheter (1.98mm or 0.078" OD), or preferably at least a 6.3 French catheter (2.079mm or 0.082" OD). However, the inner diameter of the guide sheath 400 can be smaller or larger to be compatible with other catheter sizes. In some embodiments, the working lumen can have an inner diameter that is sized to accommodate 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. In some embodiments, the working lumen can have an inner diameter of at least about 0.054" up to about 0.070", 0.071", 0.074", 0.087", 0.088" or 0.100", thereby being constructed to receive a catheter 200 having an outer diameter that fits snugly with these sizes. Regardless of the length and inner diameter, the guide sheath 400 resists kinking during distal advancement through a vessel.

[0091] The working lumen included in the sheath 400 can be sized to receive its corresponding working device with a sliding fit. The working lumen can have an inner diameter that is at least 0.001 inches larger than the outer diameter of any catheter 200 it is expected to receive, particularly when the catheter 200 will be used for suction as described in more detail below. As described in more detail below, the catheter 200 can include a slit 236 in the lumen portion 222 that is configured to slightly widen and improve the seal between the catheter 200 and the guide sheath 400 when suction is applied from a suction source. Additionally or alternatively, as described above, 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 seal achieved allows a continuous suction lumen from the distal tip of the catheter 200 to the proximal end 403 of the guide sheath (where the guide sheath 400 is connected to the suction source) even when there is a lower suction force with minimal or no leakage. Typically, when there is sufficient overlap between the catheter 200 and the guide sheath 400, there is substantially no leakage. However, when attempting to reach distal anatomical structures, the catheter 200 may be advanced to its limit, and the overlap between the catheter 200 and the guide sheath 400 is minimal. Thus, additional sealing may be desired to prevent leakage around the catheter 200 into the sheath 400. The seal between the catheter 200 and the guide sheath 400 may prevent this leakage at maximum extension of the catheter 200 relative to the sheath 400.

[0092] Distal access catheter

[0093] Refer again FIG. 2A to FIG. 2B as well as Figure 3 and 8A to Figure 8C , the distal access system 100 may include a distal access or support catheter 200 that is configured to extend through and out of the distal end of an introducer sheath 400. Figure 3 A side view of an embodiment of a catheter 200 is illustrated. The catheter 200 may include a relatively flexible distal lumen portion 222 coupled to a more rigid, kink-resistant proximal extension 230. The catheter 200 provides a rapid means of simply accessing a stroke site even through the extreme tortuosity of the cerebral vasculature. The catheters described herein have a degree of flexibility and deliverability that makes them optimally suited for advancement through the cerebral vascular anatomy without kinking or ovulation, even when navigating sharp turns. For example, the distal lumen portion 222 may perform a 180 degree turn (see FIG. 2 ). Figure 1BThe distal lumen portion 222 has a degree of flexibility that maintains the natural tortuosity of the vessel, and the distal lumen portion is advanced through the vessel without applying a straightening force, so that the natural shape and curvature of the anatomical structure is maintained during use. The catheter 200 (particularly in combination with the catheter advancement element 300 described in more detail below) provides an extended conduit beyond the guide sheath 400, which has superior delivery capabilities through tortuous anatomical structures, which allows for the transfer of suction forces to the target stroke site and the delivery of stroke intervention devices, such as stent retrievers, stents, drains or other working devices.

[0094] The inner lumen 223 extends through the lumen portion 222 between the proximal and distal ends of the lumen portion 222. The inner lumen 223 of the catheter 200 can have a first inner diameter, and the working lumen of the guide sheath 400 can have a second, larger inner diameter. When the catheter 200 is inserted through the working lumen of the sheath 400, the lumen 223 of the catheter 200 can be configured to be fluidly connected and continuous with the working lumen of the sheath 400 so that fluid flow into and / or out of the sheath 400 is possible, such as by applying suction from a suction source coupled to the system 100 at the proximal end. As the catheter 200 is advanced and withdrawn, the combination of the sheath 400 and the catheter 200 can be in continuous communication with the blood flow during suction at the proximal end.

[0095] The rotary catheter system can produce advantages over conventional catheters, particularly in distal access with respect to aspiration. The step change in the catheter column inner diameter produces a great advantage in the aspiration flow and force that can be generated by the rotary catheter 200 in combination with a conventional guide catheter. For example, where a rotary catheter 200 having a 0.070" inner diameter is paired with a standard 6F OD / 0.088" ID guide catheter (e.g., Penumbra Neuron MAX 088), an aspiration physics can be created in which the 0.088" catheter diameter will dominate and produce a 0.080 equivalent flow throughout the system.

[0096] In addition to aspiration procedures, the catheter 200 and distal access system 100 can be used for delivery tools and interventional work devices. As will be described in more detail below, a typical stent retriever to be delivered with the aid of the catheter 200 can have a 180 cm push wire control element. The distal access system 100 with a rotating support catheter 200 allows a shorter length (e.g., 120 cm-150 cm) to be used to reach the distal stroke site. The overall length can be as important as the diameter and radius when aspiration is performed with the aid of a catheter. The shorter length combined with the elimination of multiple RHVs typical in a triaxial system allows for use by a single operator.

[0097] It should be understood that where a catheter is described herein as an aspiration catheter, it should not be limited to aspiration only. Similarly, where a catheter is described herein as a delivery stent retriever or other working device, it should not be limited as such. It should also be understood that the systems described herein can be used to perform surgeries that incorporate a combination of treatments. For example, catheter 200 can be used to deliver a stent retriever delivery system, optionally in the presence of aspiration with the aid of catheter 200. As another example, a user can begin performing a first interventional procedure using the system described herein, such as an aspiration thrombectomy, and switch to another interventional procedure, such as a delivery stent retriever or implant.

[0098] It should also be understood that catheter 200 need not rotate or include proximal extension 230, but can be a non-rotating conventional catheter having a uniform diameter. The terms "support catheter," "rotating catheter," "distal access catheter," and "intermediate catheter" are used interchangeably herein.

[0099] It is desirable to have a catheter 200 with as large an inner diameter as possible that can be safely navigated to the occlusion site in order to optimize suction force and / or provide sufficient clearance for delivery of working devices in the event of suction. Depending on the patient anatomy and the clot size and composition, suitable sizes for the inner diameter of the distal lumen portion 222 can be in the range between 0.040" and 0.100", or more preferably in the range 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 segment or M2 segment of the cerebral vessel. The outer diameter (OD) should be as small as possible while still maintaining the mechanical integrity of the catheter 200. In an 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 guide sheath 400 is between 0.001" and 0.002". In another embodiment, the difference is between 0.001" and 0.004".

[0100] In some embodiments, the distal lumen portion 222 of the catheter 200 has an outer diameter (OD) that is configured to fit through a 6F introducer sheath (0.070"-0.071"), and the lumen 223 has an inner diameter (ID) that is sized to receive a 0.054" catheter. In some embodiments, the distal lumen portion 222 of the catheter 200 has an OD that is configured to fit through an 8F introducer sheath (0.088"), and the lumen 223 has an ID that is sized to receive a 0.070" or 0.071" catheter. In some embodiments, the OD of the distal lumen portion 222 is 2.1 mm and the lumen 223 has an ID of 0.071". In some embodiments, the lumen 223 has an ID of 0.070" to 0.073". The outer diameter of the guide sheath 400 can be suitable for insertion into at least the carotid artery, with the working lumen appropriately sized to provide a channel for the catheter 200 to treat occlusions at the distal end of the carotid artery toward the brain. In some embodiments, the ID of the working lumen can be approximately 0.074", and the OD of the body of the guide sheath 400 can be approximately 0.090", corresponding to a 5 French sheath size. In some embodiments In some embodiments, the ID of the working lumen can be approximately 0.087" and the OD of the body of the guide sheath 400 can be approximately 0.104" corresponding to a 6 French sheath size. In some embodiments, the ID of the working lumen can be approximately 0.100" and the OD of the body of the guide sheath 400 can be approximately 0.117" corresponding to a 7 French sheath size. In some embodiments, the guide sheath 400 ID is between 0.087" and 0.088" and the OD of the distal lumen portion 222 of the catheter 200 is approximately 0.082" and 0.086", so that the diameter difference is between 0.001" and 0.005".

[0101] In an embodiment, the lumen 222 of the catheter 200 has a uniform diameter from the proximal end to the distal end. In other embodiments, the lumen 222 of the catheter 200 is tapered and / or has a step-down toward the distal end of the distal lumen 222, so that the distal end of the catheter 200 has a smaller outer diameter than the more proximal region of the catheter 200, for example, near the more proximal region, the distal lumen 222 is sealed with a guide sheath 400. In another embodiment, as will be described in more detail below, the lumen 222 of the catheter OD steps at or near the overlap portion to more closely match the sheath inner diameter. It should be understood that this stepping of the outer diameter can be due to changing the wall thickness of the catheter 200. For example, compared with the wall thickness of the catheter 200 near the distal end, the catheter 200 can have a slightly thicker wall thickness near the proximal end to provide a better seal with the sheath. This embodiment is particularly useful in a system with more than one catheter suitable for use with a single entry sheath size. It should be understood that smaller or larger sheath sizes are contemplated herein.

[0102] The length of the lumen portion 222 can be shorter than the length of the working lumen of the guide sheath 400, so that when the lumen portion 222 is advanced toward the target location, a short overlap region 348 between the lumen portion 222 and the working lumen still exists (see Figure 2B ). Taking into account the variation of the occlusion site and the site where the distal tip 406 of the guide sheath 400 can be positioned, the length of the lumen 222 can be in the range of from about 10 cm to about 45 cm. In some embodiments, the distal lumen 222 of the catheter 200 can be between 20-45 cm, and the proximal extension 230 of the catheter 200 can be between about 90 cm to about 100 cm, so that the catheter 200 can have a total working length of approximately 115 cm. The body 402 of the guide sheath 400 can be between 80 cm to about 90 cm. In other embodiments, the working length of the catheter 200 between the proximal end of the catheter 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 of 133 cm between the proximal tab 234 (or proximal hub) and the distal tip, and the distal lumen 222 can have an axial length of about 38.7 mm.

[0103] The length of the lumen portion 222 can be less than the length of the body 402 of the guide sheath 400, so that as the catheter 200 extends from the working lumen, a seal is maintained between the overlap region 348 of the catheter 200 and the inner diameter of the working lumen. In some embodiments, the length of the lumen portion 222 is sufficient to reach the region of the M1 segment of the middle cerebral artery (MCA) and other major vessels from the internal carotid artery region, so that the proximal region of the lumen portion 222 of the catheter 200 avoids extending within the aortic arch. This limits the number of severe abnormal bend formations (angulations) that the lumen portion 222 of the catheter 200 must navigate while still reaching the target site in the more distal brain anatomy. In embodiments where the catheter 200 reaches the ICA and the distance to the embolus can be less than 20 cm, a guide sheath 400 having a sheath body 402 and a working lumen is used in combination.

[0104] A distal lumen 222 having a length of less than 30 cm (e.g., approximately 10 cm to 30 cm, such as 25 cm) can allow a seal to be created with the overlap region 348 of the body 402 while still providing adequate access to the intracranial vessels. As described above, the carotid siphon CS is an S-shaped portion of the terminal ICA that begins at the posterior bend of the cavernous ICA and terminates at the ICA bifurcation to the anterior cerebral artery ACA and the middle cerebral artery MCA. In some embodiments, as will be described in more detail below, the length of the distal lumen 222 can be between approximately 35 cm-60 cm, or between 40 cm-60 cm, or between 40 cm-45 cm to allow the distal end of the catheter 200 to extend into at least the middle cerebral artery while the proximal extension 230 remains proximal to the carotid siphon.

[0105] The distal lumen portion 222 can have a length measured from its attachment point to the proximal extension 230 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). As the lumen portion 222 extends into the target anatomical structure, an overlap region 348 can be maintained between the working lumen of the introducer sheath 400 proximate the distal region of the sheath body 402 and the lumen portion 222 of the catheter 200. It should be understood that sealing against infused or aspirated fluids can be achieved by the overlap region 348 when the OD of the catheter 200 along at least a portion of the distal lumen portion 222 substantially matches the inner diameter of the introducer sheath 400 or the difference can be between 0.001"-0.002". The difference between the catheter OD and the inner diameter of the guide sheath 400 can vary, for example, between 1 / 1000 and 2 / 1000 of an inch, or between 1 / 1000 and 4 / 1000 of an inch, or between 1 / 1000 and 12 / 1000 of an inch. Sealing between the catheter and the sheath for injected or aspirated fluids can be achieved by the overlap 348 between their substantially similar dimensions without incorporating any separate sealing structure or sealing feature.

[0106] The overlap region 348 can have a length of several centimeters and can vary depending on the distance from the embolus to the distal end of the distal lumen portion 222 (e.g., depending on how far the catheter 200 is advanced relative to the guide sheath). The overlap region 348 is sized and configured to create a seal that allows a continuous suction lumen from the distal tip region of the catheter 200 to the proximal region 403 of the guide sheath where the guide sheath 400 can be connected to a suction source. 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 overlap region 348, the suction force applied, and the material of the component. For example, the seal can be improved by increasing the length of the overlap region 348. However, increasing the length of the overlap region 348 may produce a larger length through which the suction is pulled by the lumen portion 222 of a smaller diameter, rather than by the working lumen of a larger diameter. As another example, a higher suction force applied by the suction source can produce a stronger seal between the lumen portion 222 and the working lumen even when there is a shorter overlap region 348. Further, even if the suction force is small and the overlap region 348 is short, the relatively softer material forming the lumen portion and / or body 402 can still provide an adequate seal. In an embodiment, the overlap region 348 is configured to enable sealing for vacuums up to 28inHg. In an embodiment, the overlap region 348 is configured to enable sealing for pressures up to 300mmHg, or up to 600mmHg, or up to 700mmHg with minimal or no leakage.

[0107] The catheter 200 can be telescoped upward so that the distal end of the distal lumen portion 222 can reach a cerebral vascular target in, for example, the M1 or M2 region, while the proximal end of the distal lumen portion 222 remains in the aorta. Figure 2C The aortic arch 905 is illustrated. The most distal carotid artery from the femoral entry point is the right common carotid artery 906, which exits the brachiocephalic trunk 910 (or the left common carotid artery in the so-called "cow-like anatomy," which exits the same brachiocephalic trunk 910). The distal lumen portion 222 is constructed to extend downward to the side of the aortic arch 905, or below the exit point of the brachiocephalic trunk 910. This avoids the proximal extension 230 from making a turn at the brachiocephalic exit point, which can often be very severe. The exit point of the brachiocephalic artery is often the first severe turn that catheters may traverse as they ascend to the brain. The less flexible portion of the catheter segment can avoid these increased tortuosity areas seen at the level of the internal carotid artery. The more proximal region of the distal lumen portion 222 is typically designed to approach the flexibility of the more rigid proximal extension 230 to avoid kinking. These more rigid proximal regions, including the material transition between the distal lumen portion 222 at the proximal extension 230, can remain below the tortuosity of the brachiocephalic artery turns.

[0108] In some embodiments, the distal lumen portion 222 can have a length that allows the distal end of the distal lumen portion 222 to reach the distal end of the carotid siphon into the cerebral portion of the internal carotid artery, while the proximal end of the distal lumen portion 222 (e.g., where it transitions to the proximal extension 230, as described in more detail below) remains within the aorta proximal to the point of exit of the brachiocephalic trunk 910, such as within the descending aorta 915 (see Figure 2C ). In this embodiment, the distal lumen may be between about 35 cm and 60 cm.

[0109] As mentioned above, the attachment point between the proximal extension 230 and the distal lumen portion 222 creates a transition in material and flexibility that may be prone to kinking. Thus, preferably, advancing the attachment point into an extreme bend is avoided. For example, the distal lumen portion 222 can have a length that allows the attachment point to be advanced no further than the first turn of the carotid siphon, or no further than the brachiocephalic exit point 610 or the aortic arch 905. In some embodiments, the distal lumen portion 222 has a length sufficient to allow the attachment point to remain within the descending aorta 915 while still accessing the M1 or M2 region of the neurovasculature. Positioning the material transition within the extreme bend of the brachiocephalic exit point 910 from the aortic arch 905 is generally avoided when the distal lumen portion 222 has a length between about 35 cm and about 60 cm.

[0110] As described above, a seal can be created at the overlap region 348 between the distal lumen portion 222 and the sheath body 402. It can generally be desirable to position the sealing overlap region 348 outside of the extreme bends of the neurovascular vessel. In some embodiments, the distal lumen portion 222 can have a length that allows the distal end of the distal lumen portion 222 to extend distal to the carotid siphon into the cerebral portion of the internal carotid artery while the overlap region 348 remains within the brachiocephalic artery exit point 910, the proximal end of the aortic arch 905, or the descending aorta 915. In this embodiment, the length can be between about 35 cm and about 60 cm, between about 40 cm and about 60 cm, or greater than 40 cm up to less than the working length of the sheath body 402.

[0111] As mentioned above Figure 2CAs described, the unreinforced region 407 of the distal tip 406 of the sheath 400 can have a length that allows it to provide sufficient sealing force to the outer surface of the catheter 200 when negative pressure is applied. The distal lumen portion 222 of the catheter 200 used with this embodiment of the sheath 400 can have a length shorter than 60 cm, shorter than 50 cm, shorter than 40 cm, shorter than 35 cm, shorter than 30 cm to about 10 cm. For example, the distal lumen portion 222 of the catheter 200 when used with the sheath 400 having the unreinforced region 407 configured to seal can be less than about 30 cm, for example, between 10 cm and about 30 cm.

[0112] It should be understood that the seal at the overlap region 348 can be due to the small difference between the inner diameter and the outer diameter and / or can be due to the other sealing elements located on the outer surface of the distal lumen or the inner surface of the sheath body. The sealing element can include a stepped diameter or a protruding feature in the overlap region. The sealing element can include one or more external ridge features. When the lumen is inserted into the lumen of the sheath body, one or more ridge features can be compressible. The ridge geometry can make the sealing element appear as an O-ring, a square ring or other piston seal design. The sealing element can include one or more inclined surfaces that are biased on the inner surface of the sheath body lumen. The sealing element can include one or more expandable members that are actuated to seal. The expandable or expandable member can be a balloon or a covered webbing structure, which can expand or expand at any time (including after the catheter is positioned at the desired position) and provide a seal between the two devices. Thus, there is no need to apply a sealing force on the catheter during positioning, but to apply or actuate a sealing force to seal after the positioning catheter. The sealing element may be positioned on an outer surface of the distal lumen portion, for example, near a proximal region of the distal lumen portion, and may be located within the overlapping region.More than one sealing element may be positioned along the length of the catheter.

[0113] In some embodiments, additional sealing elements can be cup seals, balloon seals or disc seals formed by soft polymers, which are positioned around the outside of the distal lumen portion near the overlap area to provide additional sealing. The sealing element can be a thin-walled tube having an outer diameter that roughly matches the inner diameter of the sheath body lumen. The tube can be sealed on one end to produce a cup seal, or sealed on both ends to form a disc or balloon seal. The balloon seal can include trapped air that produces a collapsible space. One or more slits can be formed through the wall tube so that the balloon seal can be collapsible and more easily pass through the RHV. The balloon seal does not need to include a slit for maintaining a smaller collapsible sealing element for trapped air. The sealing element can be adjustable to achieve sheath coordination and collapse.

[0114] In some embodiments, the system can include one or more features that limit the extension of the catheter 200 to a specific distance relative to the sheath 400 so that the overlap area 348 achieved is optimal and / or prevents over-insertion of the catheter 200. For example, a tab can be positioned on a region of the catheter 200 such that when the catheter 200 is inserted a selected distance through the sheath 400, the tab has a size configured to abut against a port through which the catheter 200 is inserted to prevent further distal extension of the catheter 200 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 to assist in advancing the catheter 200 into the intracranial blood vessels.

[0115] Refer again Figure 3 , the proximal extension 230 is configured to move the distal lumen 222 through the working lumen of the guide sheath 400 in a bidirectional manner so that the distal lumen 222 can be advanced out of the guide sheath 400 and into a target location for treatment within a target vessel. Figure 3As shown, the proximal extension 230 of the catheter 200 can have an outer diameter that is smaller than the outer diameter of the distal lumen portion 222, which forms a proximal spine or tether of the catheter 200. The smaller outer diameter for the proximal extension 230 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 delivery of a working device through the lumen with less friction. The significantly shorter length of the lumen portion 222 causes a step in lumen diameter between lumen portions 222 that are continuous with the working lumen, which provides a significantly increased radius and lumen area for delivering working devices and / or aspirating clots, particularly compared to other systems where the aspiration lumen extends along the entire inner diameter of the aspiration catheter. More specifically, the combined volume of the lumen area of ​​the catheter 200 and the lumen area of ​​the working lumen proximal to the distal lumen portion 222 is greater than the lumen area of ​​a large-caliber catheter along the entire length of the system. Thus, the likelihood of removing an embolus during a single aspiration attempt can be increased. More specifically, the stepped lumen diameter along the proximal extension 230 can enable greater aspiration forces to be achieved, which results in improved aspiration of the embolus. Further, this configuration of the catheter 200 and the proximal extension 230 greatly accelerates the time required to retract and re-advance the catheter 200 and / or the working device through the working lumen to exit the distal lumen 408. This describes the time taken to aspirate the occlusion. The proximal extension 230 of the catheter 200 has a length and structure that extends through the working lumen of the guide sheath 400 to the proximal end of the system 100, so that the proximal extension 230 can be used to advance and retract the catheter 200 through the working lumen. However, the proximal extension 230 of the catheter 200 only occupies a portion of the lumen space of the system 100, which results in an increased lumen area for aspiration and / or delivery of the working device. The stepped lumen diameter also increases the annular area available for forward flushing of contrast, saline or other solutions while a device such as a microcatheter or other device can be coaxially positioned within the lumen portion 222 and / or working lumen of the catheter 200. This can improve the ease and ability to perform angiography during device navigation.

[0116] In an embodiment, the distal lumen 222 of the catheter 200 is constructed to be flexible and lubricated so that it can be safely navigated to the target location. The distal lumen 222 can be anti-kink and anti-collapse when subjected to high suction forces so that clots can be effectively aspirated. The lumen 222 can have an increased flexibility toward the distal end, with a smooth material transition along its length to prevent any kink, abnormal bend formation or sharp bends in its structure, for example, during navigation of severe abnormal bend formation (such as severe abnormal bend formation with 90° or greater to 180° turns), for example, just like in the carotid siphon, at the aorta-iliac junction, the left subclavian artery lead-out point from the aorta, the lead-out point of the brachiocephalic (innominate) artery from the ascending aorta, and many other peripheral locations. The distal lumen 222 can transition from being more inflexible near its junction with the proximal extension 230 to being more flexible at the farthest end. The change in flexibility from the proximal end to the distal end of the distal lumen portion 222 can be achieved by any of a variety of methods as described herein. For example, a first portion of the distal lumen portion 222 can be formed of a material having a hardness of 72D along a first length, a second portion can be formed of a material having a hardness of 55D along a second length, a third portion can be formed of a material having a hardness of 40D along a third length, a fourth portion can be formed of a material having a hardness of 35D along a fourth length, a fifth portion can be formed of a material having a hardness of 25D along a fifth length, a sixth portion can be formed of a material such as Tecoflex having a hardness of 85A along a sixth length, and the final distal portion of the catheter can be formed of a material such as Tecoflex having a hardness of 80A. In some embodiments, the final distal portion of the distal lumen portion 222 of the catheter 200 can be formed of a material such as Tecothane having a hardness of 62A, which matches the hardness of a region of the catheter advancement element 300, which will be described in more detail below. Thus, the distal lumen portion 222 transitions from being more inflexible near its junction with the proximal extension 230 to being more flexible at the distal-most end, from which, for example, the distal tip of the catheter advancement element 300 may extend. It should be understood that other surgical catheters described herein may have similar configurations, as will be described elsewhere herein, that provide a variable relative stiffness transitioning from the proximal end to the distal end of the catheter.

[0117] The distal lumen portion 222 includes two or more layers. In some embodiments, the distal lumen portion 222 includes an inner lubricious lining, a reinforcement layer, and an outer sheath layer, each of which will be described in more detail.

[0118] The lubricated liner can be a PTFE liner having one or more thicknesses along a variable flexible section. The PTFE liner can be a tubular liner formed by dip coating or film casting a removable mandrel (e.g., a silver-plated copper wire as known in the art). Various layers with different thicknesses can be applied. For example, a base layer of etched PTFE having a thickness of about 0.005" can be formed. A second intermediate layer can be formed above the base layer, which is Tecoflex SG-80A having a thickness of about 0.0004". A third top layer can be formed above the intermediate layer, which is Tecoflex SG-93A having a thickness of about 0.0001" or less. A reinforcement layer and / or reinforcement fibers can be applied to the liner, followed by an outer jacket layer and / or additional outer coating, before the mandrel is removed by axial elongation.

[0119] The reinforcement layer is a generally tubular structure formed, for example, by a winding belt or coil or braid. The material for the reinforcement structure can 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 some embodiments, the distal lumen portion 222 has a reinforcement structure that is a nitinol belt wrapped into the coil. For example, the coil reinforcement can be a tapered nitinol belt that is set to a specific inner diameter (e.g., 0.078" to 0.085" inner diameter) and has a pitch (e.g., between 0.012" and 0.016"). The belt can be 304 stainless steel (e.g., approximately 0.012"×0.020"). Before the coil is transferred to the catheter, the coil can be heat-set. The pitch of the coil can increase from the proximal end of the distal lumen portion 222 toward the distal end. For example, the ribbon coil can have a gap between them, and the size of the gap can increase toward the distal end of the distal lumen portion 222. For example, the size of the gaps between the ribbon coils near the proximal end of the distal lumen portion 222 can be approximately a 0.016" gap, and the size of the gaps between the ribbon coils near the distal end can be larger, such as a 0.036" gap. This variation in pitch provides increased flexibility near the distal-most end of the distal lumen portion 222. The reinforcing structure can include a variety of materials and / or designs, again varying the flexibility along the length of the distal lumen portion 222.

[0120] The outer jacket layer may be composed of discrete segments of polymers having different durometers, compositions, and / or thicknesses to vary flexibility along the length of the distal lumen portion 222 as described above.

[0121] At least a portion of the outer surface of the catheter 200 may be coated with a lubricating 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 various materials as known in the art. The proximal extension 230 may also be coated to improve tracking through the working lumen. Suitable lubricating polymers are well known in the art, and they may include silicones, etc., hydrophilic polymers (such as high-density polyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides, polyvinyl pyrrolidone, polyvinyl alcohol, hydroxyalkyl cellulose, alginic acid, sugars, caprolactones, HYDAK coatings (e.g., B-23K, HydroSleek), etc., and mixtures and combinations thereof. Hydrophilic polymers may be mixed with each other or with a specified amount of water-insoluble compounds (including some polymers) to produce a coating with suitable lubricity, binding, and solubility.

[0122] In an embodiment, the distal end of the distal lumen portion 222 has a maximum force of 1500 to 3000 N-mm. 2 The flexural rigidity (E*I) within the range of 200° and the remainder of the distal lumen 222 has a higher flexural rigidity, where E is the elastic modulus and I is the area moment of inertia of the device. These units are N-mm 2 The bending stiffness range can be measured by evaluating the grams of force generated when the device is deflected a specific distance using a specific length gauge. For example, using a 3mm length dynamometer and deflecting the tip of the catheter by 2mm can generate a force of 30-60 grams, or can be between 1500-3000N-mm 2 The flexibility of the distal lumen portion 222 can be based on deflection measurements and related calculations. In comparison, the flexibility of the catheter advancement element 300 based on similar deflection measurements and calculations can be as follows. At 2 mm deflection and 3 mm dynamometer length, the catheter advancement element 300 can range between 1-5 grams of force, or can be 50-200 N-mm in bending stiffness. 2 It should be understood that other surgical catheters described herein can have a similar range of flexibility, as will be described elsewhere herein, that provides a variable relative stiffness transitioning from the proximal end to the distal end of the catheter.

[0123] Refer again FIG. 2A to FIG. 2B, the distal lumen portion 222 of the catheter 200 may have a radiopaque marker 224a at the distal tip region to assist in navigation and proper positioning of the tip under fluoroscopy. In addition, the proximal region of the catheter 200 may have one or more proximal radiopaque markers 224b so 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. In an embodiment, the two radiopaque markers (the marker 224a at the distal tip and the more proximal marker 224b) are different to minimize confusion of the fluoroscopic image, for example, the catheter proximal marker 224b may be a single band, and the marker 411 on the guide sheath 400 may be a double band, and any marker on the working device delivered by the distal access system may have another type of band or marker. The radiopaque markers 224 of the distal lumen 222 (particularly markers near the distal tip region for navigating extremely tortuous anatomical structures) can be relatively flexible so that they do not affect the overall flexibility of the distal lumen 222 near the distal tip region 222. The radiopaque markers 224 can be tungsten-loaded or platinum-loaded markers, which are relatively flexible compared to other types of radiopaque markers used in devices where flexibility is not the most important. In some embodiments, the radiopaque marker can be a band of tungsten-loaded PEBAX with a hardness of 35D.

[0124] like FIG. 8B to FIG. 8CAs best shown in FIG. 1 , at least one reinforcing fiber 801 can be incorporated into the wall of the distal lumen portion 222 to prevent the curled reinforcing layer 803 from stretching. The fiber 801 can be positioned between the lining layer 805 and the reinforcing layer 803. The fiber 801 can extend from the proximal region of the distal lumen portion 222 to the distal region of the portion 222 along the longitudinal axis A of the catheter 200. The proximal end of the fiber 801 can be coupled to the region of the distal lumen portion 222 near which the distal lumen portion 222 is coupled to the location of the proximal extension. 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 completely encapsulated between the liner 805 and the outer sheath 807. In some embodiments, the distal end of the fiber 801 extends at the distal end of the last coil of the reinforcement layer 803, which extends below the marker band 224a and then returns to wrap around the band 224a in the proximal direction. Thus, the free end of the fiber 801 is captured below the reinforcement layer 803 and the marker band 224a. Thus, the reinforcement fiber 801 terminates at the position where the reinforcement layer 803 terminates, leaving a length of about 10cm-12cm between the farthest tip area that is not enhanced. The catheter 200 may include a plurality of reinforcement 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 portion 222 and aligned parallel to each other and to the longitudinal axis A of the catheter 200. The material of the reinforcement fiber 801 can vary, including but not limited to various high-toughness polymers, such as polyester, PEEK and other similar materials.

[0125] As mentioned previously, the proximal extension 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 passing out of the distal lumen 408. In an embodiment, the length of the proximal extension 230 is longer than the entire length of the guide sheath 400 (from the distal tip to the proximal valve), such as about 5 cm to 15 cm. 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 extension 230 can be between 90 and 100 cm.

[0126] Refer again Figure 3, the proximal extension 230 may include one or more markings 232 to indicate overlap between the distal lumen portion 222 of the catheter 200 and the sheath body 402 and 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 a first marking 232a may be an RHV proximity marking positioned so that when the marking 232a is aligned with the sheath proximal hemostasis valve 434 during insertion of the catheter 200 through the introducer sheath 400, the catheter 200 is positioned in the most distal position with the minimum overlap length required to create a seal between the catheter 200 and the working lumen. At least a second marking 232b may be a fluorine protection marking that may be positioned on the proximal extension 230 and located a distance from the distal tip of the distal lumen portion 222. In some embodiments, the marking 232 may be positioned approximately 100 cm from the distal tip of the distal lumen portion 222.

[0127] The proximal extension 230 may include a gripping feature, such as a tab 234 on the proximal end, which makes the proximal extension 230 easy to grasp and advance or retract. As will be described in more detail below, the tab 234 can be coupled to one or more other components of the system. The proximal tab 234 can be designed to be easily identified in any other device (such as a guide wire or a retractable stent device wire) that can be inserted into the sheath proximal valve 434. A portion of the proximal extension 230 and / or the tab 234 can be colored in a bright color or marked with a bright color so that it can be easily distinguished from a guide wire, a retractable stent tether, etc. In the case of using multiple catheters 200 together in a nested style to reach a more distal position in the brain, each proximal extension 230 and / or tab 234 can be color-coded or otherwise marked to clearly show the operator which proximal extension 230 of which catheter 200 it is coupled to. The proximal portion 366 of the catheter advancing element 300 may also include a color that distinguishes it from the proximal extension 230 of the catheter 200 .

[0128] Tab 234 may be integrated with or in addition to a proximal hub that is coupled to the proximal end of proximal extension 230. For example, as will be described in more detail below, proximal extension 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 proximal extension 230 so that suction and / or fluid may be delivered via the proximal hub by means of the hypotube.

[0129] The proximal extension 230 can be constructed with sufficient rigidity to allow advancement and retraction of the distal lumen 222 of the catheter 200, yet flexible enough to navigate through the brain anatomy as needed without kinking. The configuration of the proximal extension 230 can vary. In some embodiments, the proximal extension 230 can be a tubular element having an outer diameter that is approximately the same as the outer diameter of the distal lumen 222, similar to a typical catheter device. In other embodiments, the outer diameter of the proximal extension 230 is sized as described above to avoid occupying too much lumen area in the lumen of the guide sheath 400.

[0130] The proximal extension 230 may be a solid wire having a circular, rectangular, trapezoidal, D-shaped, or elliptical cross-sectional shape (see FIG. 4A to FIG. 4G ). The proximal extension 230 may be a Figure 4A The flattened ribbon may have a rectangular cross-sectional shape as shown. The flattened ribbon may also have a square, rectangular, or other cross-sectional shape. The ribbon may be curved into a circle, an ellipse, a C-shape, or a quarter circle, or other cross-sectional area along an arc. It can be seen that the inwardly facing surface of the ribbon may be generally flat, and the outwardly facing surface of the ribbon (i.e., the surface configured to abut against the inner diameter of the access sheath through which it extends) may be generally curved (see FIG. Figures 4F to 4G ). The curvature of the surface can roughly match the curvature of the inner surface of the entry sheath. The cross-sectional shape of such a band produced can be generally trapezoidal. The overall size of the band can vary depending on its cross-sectional shape and the size of the distal lumen portion. A 0.054" size catheter 200 can have a proximal extension 230 that is trapezoidal or D-shaped in cross-section. The inwardly facing flat surface can have a width that is approximately 0.020" wide, and in the case of a trapezoidal shape embodiment, the outwardly facing curved surface can extend along an arc that is approximately 0.030" long. A 0.070" size catheter 200 can have a proximal extension that is trapezoidal or D-shaped in cross-section, and the width of the inwardly facing flat surface is slightly larger, for example, approximately 0.025", and in the case of a trapezoidal shape embodiment, the outwardly facing curved surface can extend along an arc that is approximately 0.040" long. A 0.088" size catheter 200 may have a proximal extension that is trapezoidal or D-shaped in cross section with an inwardly facing flat surface approximately 0.035" wide and an outwardly facing curved surface of a trapezoidal shaped embodiment may extend along an arc approximately 0.050" long.

[0131] The proximal extension 230 may be a hollow wire having a lumen 235 extending therethrough, such as Figure 4BThe hypotube shown. The hypotube can have an oval or circular shape. In an embodiment, the proximal extension 230 is a stainless steel strip having dimensions of approximately 0.012"×0.020". In an embodiment, the proximal extension 230 is a stainless steel strip having dimensions of approximately 0.014"×0.020". In an embodiment, the proximal extension 230 is a round wire having dimensions from 0.014" to 0.018". In another embodiment, the proximal extension 230 is a strip having dimensions ranging from 0.010" to 0.015" thick, and 0.015" thick to 0.025" thick. In an embodiment, the proximal extension 230 is a hypotube formed from a flattened strip of rigid material that is rolled into a tubular shape to have a lumen 235. In some embodiments, proximal extension 230 can be formed from a flattened stainless steel strip and rolled into a hypotube such that proximal extension 230 has a wall thickness of about 0.007", an inner diameter of about 0.004", and an outer diameter of about 0.018" prior to modifying the hypotube into an elliptical cross-sectional shape. The ovalized hypotube can maintain an inner diameter of at least 0.001" along at least a first dimension and an outer diameter of at least 0.015" along at least a first dimension. In an embodiment, the proximal extension 230 material is a metal such as stainless steel or nitinol and a plastic such as any of a variety of polymers. In an embodiment, proximal extension 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 extension 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 Illustrated is a cross-sectional view of a working lumen of a sheath 400 having a proximal end portion 230 extending therethrough. The proximal end portion 230 has a rectangular cross-sectional shape. Figure 4D A cross-sectional view of a working lumen is illustrated having an ovalized hypotube proximal portion 230 and a catheter advancing element 300 extending therethrough. Figure 4EA comparison of surface area between a rectangular band and an oval hypotube is illustrated. An oval hypotube has a smaller surface area than a rectangular band, which allows, for example, a greater flow rate through the working lumen during application of a suction force. The material, size, and shape of the proximal extension 230 can be selected based on the material, size, and shape of the distal lumen portion 222. For example, the proximal extension 230 can be a 0.012"x0.020" rectangular band of 340 stainless steel, and the distal lumen portion 222 can have an inner diameter of about 0.054" to about 0.072". In another embodiment, the proximal extension 230 can be a 0.014"x0.020" rectangular band of 340 stainless steel, and the distal lumen portion 222 can have an inner diameter of about 0.088". The additional weight of the stainless steel band 230 can be useful in advancing a larger inner diameter catheter without kinking.

[0132] Now refer to FIG. 5A to FIG. 5F , the joint between the distal lumen portion 222 and the proximal extension portion 230 of the catheter 200 can be constructed to allow a smooth transition of flexibility between the two parts so as not to create kinks or weak points. The smooth transition of the joint between the distal lumen portion 222 and the proximal extension portion 230 also allows the device to smoothly pass through the continuous inner lumen created by the working lumen of the guide sheath 400 and the lumen 223 of the lumen portion 223 of the catheter 200. In an embodiment, the distal lumen portion 222 has a transition section 226, near which the lumen portion 222 is coupled to the proximal extension portion 230 (see Figure 5A). The transition section 226 may have an angled cut so that there is no sudden step 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 planar. In an alternative embodiment, the angled cut is curved or stepped to provide a smoother transition zone. It should be understood that the proximal region of the distal lumen portion 222 may be angled in an oblique manner relative to the longitudinal axis of the catheter 200 so that the proximal end and the proximal opening entering the lumen are at an angle different from 90° with the longitudinal axis of the catheter 200, for example, between approximately 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40° or 45° until less than 90°. The proximal region of the distal lumen portion 222 may also be aligned approximately vertically with the longitudinal axis of the catheter 200 so that the proximal end and the proximal opening entering the lumen are approximately 90° with the longitudinal axis of the catheter 200. Similarly, the distal region of the distal lumen portion 222 can be angled in an oblique manner relative to the longitudinal axis of the catheter 200, such that the distal end and the distal opening away from the lumen 223 are at an angle different from 90° 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 can also be aligned approximately perpendicularly to the longitudinal axis of the catheter 200, such that the distal end and the distal opening into the lumen are approximately 90° to the longitudinal axis of the catheter 200.

[0133] The proximal extension 230 can be coupled to the proximal region of the catheter 200 and / or can extend along at least a portion of the distal lumen 222 such that the proximal extension 230 is coupled to the distal lumen 222 at a distance away from the proximal end. The proximal extension 230 can be coupled to the distal lumen 222 by various mechanisms, including bonding, welding, gluing, clamping, stringing, tying or fastening one or more components that make up the proximal extension 230 and / or portion 222. The distal lumen 222 and the proximal extension 230 can be joined by welding, mechanical bonding, adhesive bonding or a combination thereof. In some embodiments, the proximal extension 230 and the lumen 222 are coupled together by sandwiching the proximal extension 230 between the layers of the distal lumen 222. For example, the proximal extension 230 can be a hypotube or a rod having a distal end that is thinned, ground, or cut so that the distal end can be laminated or otherwise attached to a layer of the catheter portion 222 near the proximal region. The area of ​​overlap between the distal end of the proximal extension 230 and the portion 222 can be at least about 1 cm. This type of coupling allows for a smooth and uniform transition from the proximal extension 230 to the lumen portion 222.

[0134] Still refer to FIG. 5A to FIG. 5F, the transition section 226 of the distal lumen portion 222 can open upward into a groove 238, which extends a length at the proximal end of the transition section 226. In some embodiments, the groove 238 has a generally curved cross-sectional geometry. For example, the groove 238 can extend about 20 to about 90 degrees along the arc of the longitudinal axis of the catheter 200. In some embodiments, the groove 238 is curved to create a funnel shape and assist in loading and reloading the catheter advancement element 300 into the lumen of the catheter 200. In other embodiments, the edge of the groove 238 is curved so that the groove 238 is generally uneven. The curved shape can vary, including a teardrop shape, which allows a smooth transition and better loading / reloading of the catheter advancement element 300 into the lumen and avoids a flat edge that can abut and capture components as it is inserted. In other embodiments, the groove 238 is generally flat. When the device is forced to bend, the groove 238 can provide a smooth transition between the distal lumen portion 222 and the proximal extension 230. This reduces the likelihood of kinking and promotes push resistance.

[0135] The proximal region of distal lumen 222 may include one or more markers to provide visualization under fluorine during loading / reloading of catheter advancing element 300. For example, the proximal region may include a region of Pebax (e.g., 35D) loaded with tungsten (80%) for radiopacity.

[0136] The distal end of the proximal extension 230 and / or the distal lumen 222 may have features that facilitate mechanical engagement during welding, such as a textured surface, protruding features, or cut-off features. During the thermal welding process, the features will facilitate mechanical bonding between the polymer distal lumen 222 and the proximal extension 230. For example, 6A to 6F As shown, the proximal end of the distal lumen portion 222 may include a short matching sleeve 240 that is coupled to the proximal edge 221 of the distal lumen portion 222. The sleeve 240 may include an inner lumen extending between the proximal opening 242 and the distal opening 241. The distal end of the proximal extension 230 may be inserted through the proximal opening 242 and the inner lumen of the sleeve 240 to couple the proximal extension 230 to the distal lumen portion 222. In some embodiments, the proximal extension 230 may be coupled to the distal lumen portion 222 so that the distal opening 231 of the hypotube forming the proximal extension 230 may communicate with the lumen 223 of the distal lumen portion 222, for example, via the distal opening 241 of the sleeve 240. The sleeve 240 may also provide a transition between the distal lumen portion 222 and the proximal extension 230 similar to the groove 238. The distal lumen portion 222 need not include a matching sleeve 240 to couple with the proximal extension 230. For example, the distal end of the proximal extension 230 can be inserted through the wall of the slot 238 at the proximal end of the distal lumen portion 222 (see Figure 5A , FIG. 5E to FIG. 5F ). The distal end of the proximal extension 230 can extend along the length of the groove 238 and along at least a length of the wall of the distal lumen 222. The connection between the proximal extension 230 and the distal lumen 222 can be modified later as an inventive point, and the above are various connection methods.

[0137] As mentioned above, the lumen 222 of the catheter 200 can have a uniform diameter or wall thickness from the proximal end to the distal end, or the lumen 222 can have different outer diameters or wall thicknesses along its length. For example, the distal end of the distal lumen 222 can have a smaller outer diameter than the more proximal region of the distal lumen 222. FIG. 5A to FIG. 5B , FIG. 5E to FIG. 5F as well as Figures 6A to 6B , FIG. 6E to FIG. 6F and Fig. 8A The distal lumen portion 222 is shown having a distal tubular region or distal tube 245 having a smaller outer diameter, and a proximal tubular region or proximal tube 246 having a larger outer diameter. The distal tube 245 transitions to the proximal tube 246 via a step 247. Figure 5A and Fig. 6A As best shown, the inner diameters of the distal tube 245 and the proximal tube 246 are approximately the same, which provides a smooth inner wall surface for the lumen 223. The outer diameter of the distal tube 245 is less than the outer diameter of the proximal tube 246. The step 247 is formed by the transition of the wall thickness between the distal tube 246 and the proximal tube 247. In some embodiments, the outer diameter of the distal tube 246 can be about 0.080" to about 0.084", and the outer diameter of the proximal tube 247 can be about 0.087" to about 0.088".

[0138] At least a portion of the wall of the larger outer diameter proximal tube 246 may be discontinuous such that it includes the slit 236 (see FIG. 5A to FIG. 5C , FIG. 5E to FIG. 5F , FIG. 6A to FIG. 6C as well as FIG. 6E to FIG. 6F ). The slit 236 can extend a 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 of the length of the proximal tube 247. The slit 236 can, but need not, extend along the entire length of the proximal tube 247 to the location of the step-in portion 247. In addition, the proximal tube 247 can include more than one slit 236. The slit 236 can be positioned in the larger diameter proximal tube 246 at a location opposite to where the distal end of the proximal extension 230 is coupled to the wall of the distal tube cavity portion 222. It can be seen that the distal end of the proximal extension 230 embedded in the wall of the proximal tube 246 is positioned opposite the slit 236 (see Figure 5C and Figure 6C ). It should be appreciated that the slit 236 may be positioned around the proximal tube 246 at another location.

[0139] The slit 236 can allow the proximal tube 246 to expand slightly so that the ends of the wall forming the slit 236 separate, which forms a gap between them. For example, when the catheter 200 is inserted through the working lumen of the sheath 400, the outer diameter can be received in a sliding fit so that at least the overlap area 348 is retained. When a suction force is applied through the working lumen, for example by applying suction from a suction source coupled to the proximal end 403 of the guide sheath 400, the seal provided at the overlap area 348 can be enhanced by slightly widening the gap formed by the slit 236. 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 because the outer surface of the wall of the catheter 200 can be pressed against the inner surface of the working lumen, which creates 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 leakage of blood from the blood vessel into the working lumen directly through the distal opening 408. Thus, the larger outer diameter of the proximal tube 246 combined with the slit 236 can enhance the seal between the catheter 200 and the sheath 400 by accommodating changes in the inner diameter of the sheath. The slit 236 can effectively increase the outer diameter of the proximal tube 246 depending on whether the walls forming the slit 236 are separated by a distance. The walls forming the slit 236 can 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, can be the same as or larger than the inner diameter of the sheath through 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 close to each other and there is no gap, the outer diameter of the proximal tube 246 can be 0.081". When the walls forming the slit 236 are separated from each other by a maximum distance, the outer diameter of the proximal tube 246 can increase to about 0.087". Additionally, the increased wall thickness of the proximal tube 246 allows for a more robust joint between the distal lumen portion 222 and the proximal extension 230 of the catheter.

[0140] Additionally or alternatively, the distal tip 406 of the sheath 400 may include one or more features that 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 as described elsewhere herein.

[0141] Catheter Advancement Element

[0142] As mentioned above, the distal access system 100 may, but need not, include a catheter advancement element 300 for delivering the catheter 200 to the distal anatomical structure. It should be understood that in the case where the catheter 200 is described herein as being used with or advanced with the catheter advancement element 300, the catheter advancement element 300 need not be used to deliver the catheter 200 to the target location. For example, other advancement tools, such as microcatheters and / or guidewires known in the art, will be considered here. Similarly, the catheter advancement element 300 can be used together to advance other catheters other than the catheter 200 described herein. For example, the catheter advancement element 300 can be used to deliver a 5MAX reperfusion catheter (Reperfusion Catheter) (Alameda, California, Pinumblr, Inc.) or other reperfusion catheters known in the art for clot removal in patients with acute ischemic stroke. Although the catheter advancement element 300 is described herein with reference to the catheter 200, it should be understood that the catheter advancement element can be used to advance other catheters and is not intended to limit its use.

[0143] As described above, the distal access system 100 can provide fast and simple access to distal target anatomical structures, particularly tortuous anatomical structures of cerebral vessels. The flexibility and deliverability of the distal access catheter 200 allow the catheter 200 to take the shape of tortuous anatomical structures and avoid applying straightening forces that create new anatomical structures. The distal access catheter 200 can achieve this even in the presence of a catheter advancement element 300 extending through the lumen of the distal access catheter 200. Thus, the flexibility and deliverability of the catheter advancement element 300 are equal to or better than the flexibility and deliverability of the distal lumen portion 222 of the distal access catheter 200, because both are constructed to reach the middle cerebral artery (MCA) circulation without clearing the curves of anatomical structures along the way.

[0144] The catheter advancement element 300 may include a non-expandable flexible elongated body 360 coupled to a proximal portion 366. The elongated body 360 may be received within and extend through the inner lumen 223 of the distal lumen portion 222 of the catheter 200 (see Figure 2B ). The distal tip 346 of the catheter advancement element 300 may be as Figure 2B360 and the catheter system 100 as a whole. The elongated body 360 can be inserted through the inner lumen 223 of the lumen portion 222 in a coaxial manner. The outer diameter of at least one region of the elongated body 360 can be sized to substantially fill the inner lumen 223 of the lumen portion 222.

[0145] The overall length of the catheter advancement element 300 (e.g., between the proximal end and the distal-most tip) can vary, but is generally long enough to extend through the support catheter 200 plus at least a distance beyond the distal end of the support catheter 200, while at least a length of the proximal portion 366 remains outside the proximal end of the guide sheath 400. In some embodiments, the overall length of the catheter advancement element 300 is about 149 cm, and the working length is 143 cm from the proximal tab or hub to the distal-most tip. The elongated body 360 can have a length at least as long as the lumen 222 of the catheter 200, but it should be understood that the elongated body 360 can be shorter than the lumen 222 as long as at least a length remains within the lumen 222 when the distal end of the elongated body 360 extends at the distal end of the lumen 222. In some embodiments, the axial length of the distal lumen 222 can be about 39 cm, and the insertion length of the elongated body 360 can be at least about 48.5 cm, 49 cm, or about 49.5 cm. The proximal portion 366 may also have a variable length. In some embodiments, the proximal portion 366 is about 94 cm. The distal portion extending at the distal end of the distal end of the lumen portion 222 may include a distal tip 346 that protrudes beyond a length of the distal end of the lumen portion 222 during the use of the catheter advancement element 300. As will be described in more detail below, the distal tip 346 of the elongated body 360 that is configured to protrude distally from the distal end of the lumen portion 222 assists the navigation of the catheter system through the tortuous anatomical structure of the cerebral blood vessel. The proximal portion 366 coupled to the elongated body 360 and extending proximally from the elongated body 360 can be aligned substantially side by side with the proximal extension 230 of the catheter 200. As will be described in more detail below, the structure between the elongated body 360 and the lumen portion 222 can be maintained during the catheter's advancement through the tortuous anatomical structure to reach the target position for treatment in the distal blood vessel, and assists in preventing the distal end of the catheter 200 from being stuck on the tortuous branch blood vessel.

[0146] In some embodiments, the elongated body 360 can have a region of relatively uniform outer diameter extending along at least a portion of its length, and the distal tip 346 tapers downward from the uniform outer diameter. When the catheter advancement element 300 is inserted through the catheter 200, the tapered distal tip 346 is configured to extend beyond and protrude through the distal end of the lumen 222, while the more proximal region of the body 360 with uniform diameter remains within the lumen 222. As mentioned, the distal end of the lumen 222 can be blunt and have no variation in the size of the outer diameter, while the distal tip 346 can be tapered, which provides an overall elongated tapered geometry of the catheter system. The outer diameter of the elongated body 360 is also close to the inner diameter of the lumen 222, minimizing the stepping of the outer diameter from the elongated body 360 to the lumen 222. Minimizing this stepping prevents problems with the lip formed by the distal end of the lumen portion 222 getting caught on a tortuous neurovascular vessel (such as around the carotid siphon near the ophthalmic artery branch) as the distal tip 346 bends and curves along the vascular anatomy. In some embodiments, the inner diameter of the lumen portion 222 can be 0.054", and the outer diameter of the elongated body 360 can be 0.048", so that the difference therebetween is approximately 0.006". In some embodiments, the inner diameter of the lumen portion 222 can be 0.070", and the outer diameter of the elongated body 360 can be 0.062", so that the difference therebetween is approximately 0.008". In some embodiments, the inner diameter of the lumen portion 222 can be 0.088", and the outer diameter of the elongated body 360 can be 0.080", such that the difference therebetween is approximately 0.008". In some embodiments, the inner diameter of the lumen portion 222 can be 0.072", and the outer diameter of the elongated body 360 is 0.070", such that the difference therebetween is approximately 0.002". In other embodiments, the outer diameter of the elongated body 360 is 0.062", such that the difference therebetween is approximately 0.010". Although the outer diameter of the elongated body 360 extends through the lumen of the lumen portion 222, the lumen portion 222 and the elongated body 360 extending therethrough in a coaxial fashion are flexible enough to navigate tortuous anatomical structures leading to the level of the M1 or M2 arteries without kinking and without damaging the vessels.

[0147] The length of the distal tip 346 (e.g., the area of ​​the catheter advancement element 300 that is configured to extend distally of the distal end of the catheter 200 during use) can vary. In some embodiments, the length of the distal tip 346 can be in the range of about 0.50 cm to about 3.0 cm from the most distal end of the elongated body 360. In other embodiments, the length of the distal tip 346 is at least about 0.8 cm. In other embodiments, the length of the distal tip 346 is between 2.0 cm and about 2.5 cm. In some embodiments, the length of the distal tip 236 varies depending on the inner diameter of the elongated body 360. For example, the length of the distal tip 236 can be as short as 0.5 cm, and the inner diameter of the catheter 200 can be 0.054". The distal tip 346 can be a constant taper from the outer diameter of the elongated body 360 downward to a second smaller outer diameter at the distal tip. In some embodiments, the constant taper of the distal tip 346 can be from about 0.048" outer diameter downward to about 0.031" outer diameter. In some embodiments, the constant taper of the distal tip 346 can be from 0.062" outer diameter to about 0.031" outer diameter. In yet other embodiments, In one embodiment, the constant taper of the distal tip 346 can be from 0.080" outer diameter to about 0.031" outer diameter. 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 depending on the outer diameter of the slender body 360. For example, the taper can be between 0.9 and 1.6 degrees relative to horizontal. The taper can be at an angle of 2-3 degrees to the centerline of the slender body 360.

[0148] It should be understood that the distal tip 346 need not taper, and its soft, atraumatic and flexible properties can be achieved due to material properties rather than changes in outer dimensions to facilitate intravascular navigation of emboli in tortuous anatomical structures. In addition or alternatively, the distal tip 346 of the elongated body 360 can have a flexible transition along its length. The most flexible area of ​​the distal tip 346 can be its distal terminus. Moving along the length of the distal tip 346 from the distal terminus toward the area proximal to the distal terminus, the flexibility can gradually approach the flexibility of the distal end of the lumen portion 222. For example, the distal tip 346 can be formed of a material with a hardness of no more than 35D or about 62A, and transition to a proximal end toward increasingly harder materials with a hardness of no more than 55D and 72D until the proximal end 366, which can be a stainless steel hypotube, or a combination of material properties and a tapered shape. The material used to form the region of the elongated body 360 can include PEBAX (e.g., PEBAX 25D, 35D, 55D, 72D) with a lubricating additive compound such as Mobilize (Compounding Solutions, Lewiston, Maine). In some embodiments, the material used to form the region of the elongated body 360 can be Tecothane 62A. Incorporating the lubricating additive directly into the polymer elongated body means that incorporating a separate lubricating lining (such as a Teflon lining) is unnecessary. This allows a more flexible element that can navigate distal brain anatomy and is less likely to kink. Similar materials can be used to form the distal lumen portion 222 of the catheter 200, which provides similar advantages. It should also be understood that the flexibility of the distal tip 346 can be achieved by a combination of a flexible lubricating material and a tapered shape. For example, the length of the tip 346 can be kept shorter than 2cm-3cm, but the optimal delivery capacity is maintained due to the change in the flexible material from the farthest tip toward a more proximal region at a distance from the farthest tip. In an embodiment, the elongated body 360 is formed of a PEBAX (polyether block amide) embedded silicone designed to maintain the highest degree of flexibility. It should be understood that the wall thickness of the distal end of the lumen portion 222 can also be made thin enough so that the lip formed by the distal end of the lumen portion 222 relative to the elongated body 360 is minimized.

[0149] As mentioned above, the elongated body 360 can be configured to have variable stiffness between the distal and proximal ends of the elongated body 360. The flexibility of the elongated body 360 is highest at the most distal end of the distal tip 346, and can gradually transition in flexibility to the flexibility of the distal end near the lumen 222, which is generally not as flexible as the most distal end of the distal tip 346. When the catheter advancement element 300 is inserted through the catheter 200, the area of ​​the elongated body 360 extending beyond the distal end of the lumen 222 can be the most flexible, and the area of ​​the elongated body 360 that is configured to align with the distal end of the lumen 222 during advancement in the blood vessel can have approximately the same flexibility as the distal end of the lumen 222 itself. It can be seen that the flexibility of the distal end of the lumen 222 and the flexibility of the body 360 just proximal to the extension (whether tapered or not) can be approximately the same. This provides a smooth transition in material properties to improve the tracking of the catheter system through tortuous anatomical structures. Further, the more proximal segments of the elongated body 360 can be less flexible and increasingly rigid. It should be understood that the change in flexibility of the elongated body 360 can be a function of material differences, dimensional changes (e.g., by tapering), or a combination of both. The benefit of the elongated body 360 over a microcatheter is that it can have a larger 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 anatomical structures. 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 cause damage to one or both of the components and increase risk to the patient during the procedure. The gap results in a fit that is too tight to provide optimal relative sliding. When the gap between the two components is too loose (e.g., greater than about 0.010"), the distal end of the catheter 200 forms a lip that is prone to snagging on branch vessels during advancement through tortuous neurovascular vessels (such as around the carotid siphon at the ophthalmic artery bifurcation).

[0150] The gap of ID / OD between the elongated body 360 and the distal lumen portion 222 can be within this size range (e.g., 0.003"-0.010") along most of their length. For example, the elongated body 360 can have a relatively uniform outer diameter, which is between about 0.048" and about 0.080" from the proximal region to the distal region until 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, which is between about 0.054" and about 0.088" from the proximal region to the distal region. It can be seen that the difference between their respective inner and outer diameters along most of their length can be within such a gap size range of 0.003" to 0.010". However, it should be understood that the distal tip 346 of the tapered elongated body 360 will have a larger gap size relative to the inner diameter of the distal lumen portion 222. However, during use, the tapered distal tip 346 is constructed to extend distally of the distal end of the catheter 200 so that a region of the elongated 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 so that it can minimize a lip at the distal end of the catheter 200.

[0151] The elongated body 360 can be formed by various materials that provide suitable flexibility and lubricity. Example materials include high-density polyethylene, 72D PEBAX, 90D PEBAX or equivalent rigidity and lubricity materials. At least a portion of the elongated body 360 can be enhanced to improve navigation and torque (e.g., braided reinforcement layer). The flexibility of the elongated body 360 can be increased 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 proximal region of the elongated body can 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 can terminate at a distance from the proximal end of the distal tip 346. For example, the distance from the end of the webbing to the distal tip may be from about 10 cm to about 15 cm or from about 4 cm to about 10 cm or from about 4 cm to about 15 cm.

[0152] 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 that extends parallel to the longitudinal axis of the catheter advancement element 300 (see 7A to 7C as well as FIG. 10A to FIG. 10C). In an embodiment, the single lumen 368 of the elongated body 360 is sized to accommodate a guidewire, however it should be understood that the use of the catheter advancement element 300 generally eliminates the need for a guidewire lead. The guidewire can extend generally concentrically through the single lumen 368 from the proximal opening to the distal opening through which the guidewire can extend. 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-wire (OTW) approach. In other embodiments, the proximal opening is a rapid exchange opening 362 through the wall of the catheter advancement element 300, such that the catheter advancement element 300 is configured for rapid exchange, rather than for 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 away from the proximal tab 364 and distal to the proximal end 366 (see FIG. 7A to FIG. 7B and Fig.7D ). The proximal opening 362 can be located at a distance of about 10 cm from the distal tip 346 to about 20 cm from the distal tip 346. In some embodiments, the proximal opening 362 can be located near the area where the elongated body 360 joins the proximal end 366, for example, just distal to the end of the hypotube (see Figure 7B In other embodiments, the proximal opening 362 is positioned more distally, such as about 10 cm to about 18 cm from the distal end of the elongated body 360 (see Fig.7D ). The proximal opening 362, which is positioned closer to the distal tip 346, allows the catheter advancement element 300 to be more easily removed from the catheter 200, which leaves the guidewire in place for a "quick exchange" type of surgery. Quick exchange relies on only a single person to perform the exchange. The catheter advancement element 300 can easily replace another device using the same guidewire that remains in place. The single lumen 368 of the elongated body 360 can be configured to receive a guidewire having a diameter in the range of 0.014" and 0.018", or in the range of 0.014" and 0.022". In this embodiment, the inner lumen diameter of the elongated body 360 can be between 0.020" and 0.024". The guidewire, catheter advancement element 300, and catheter 200 can all be coaxially assembled for insertion through the working lumen of the guide sheath 400. The inner diameter of the lumen 368 of the elongated body 360 can be 0.019" to approximately 0.021".

[0153] Fig.7DAnother embodiment of a catheter advancement element 300 configured for rapid exchange is shown. The rapid exchange configuration can significantly shorten the length of the device, reduce staffing requirements, and reduce fluoroscopy. Similar to other embodiments described herein, the catheter advancement element 300 can include a non-expandable flexible elongated body 360 coupled to a proximal portion 366, which is coupled to a proximal tab 364 or a hub 375. As described elsewhere herein, the area near the distal tip 346 can be tapered so that the outer diameter tapers over a length of about 1 cm to about 3 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". Also as described elsewhere herein, the distal tip 346 can be formed of a material having a hardness (e.g., 62A and 35D) that transitions toward an increasingly harder material having (e.g., 55D and 72D) toward the proximal end until the proximal portion 366. For example, Fig.7D The segment 371 of the elongated body 360 including the distal tip 346 is illustrated to have a hardness of 35D and a length of about 10cm to about 12.5cm. The segment 371 of the elongated body 360 including the distal tip 346 can have a hardness of 62A and a length of about 10cm to about 12.5cm. The segment 372 of the elongated body 360 can have a hardness of 55D and a length of about 5cm to about 8cm. The segment 373 of the elongated body 360 can have a hardness of 72D and can be about 25cm to about 35cm in length. The three segments 371, 372, 373 in combination can form an insertion length of the elongated body 360, and the proximal end 366 is coupled to the elongated body 360 from the insertion length to the end point of the distal tip 346, which can be about 49cm in length.

[0154] FIG. 10A to FIG. 10C An embodiment of a catheter advancement element 300 incorporating a reinforcement layer 380 is illustrated. As mentioned above, the reinforcement layer 380 can be a webbing or other type of reinforcement to improve the torquability of the catheter advancement element 300 and help bridge the components of the catheter advancement element 300 that have such flexibility differences. 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 webbing positioned between the inner and outer layers of Pebax 382, ​​384 (see Fig. 10C ). The reinforcement layer 380 may terminate a distance proximal to the distal tip region 346. For example, Fig. 10AAn elongated body 360 is illustrated having a segment 371 and a segment 373 located proximal to the segment 371. The segment 371 may include a distal tip 346 having a hardness of up to about 35D. The segment 371 is an unreinforced polymer having a length of about 4 cm up 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 up 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 the reinforcement exists near the transition between the proximal portion 366 and the elongated body 360.

[0155] Refer again Fig.7D , the entry port 362 for the surgical guide wire 805 can be positioned a distance from the distal end of the elongated body 360. In some embodiments, the entry / exit port 362 can be about 18 cm from the distal end, which creates a rapid exchange wire entry / exit segment 370. The outer diameter of the elongated body 360 within the segments 370 (segments 371 and 372) can be about 0.080"-0.082", while the segment 373 at the proximal end of the rapid exchange wire entry / exit segment 370 can have a step-down in outer diameter, such as about 0.062"-0.064".

[0156] In other embodiments, the entire catheter advancement element 300 can be a tubular element that is configured to receive a guidewire via the proximal portion 366 and the elongated body 360. For example, the proximal portion 366 can be a hypotube or a tubular element having a lumen that communicates with a lumen 368 extending through the elongated body 360 ( Figure 3 366). In some embodiments, the proximal portion 366 can be a skived 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 the over-the-wire version, the proximal portion 366 can be a skived hypotube coupled to the proximal hub 375. The proximal portion 366 can extend eccentrically or concentrically with the distal lumen portion 222. As shown in FIG. Fig. 7EAs best shown in , the proximal portion 366 can be a stainless steel hypotube as described elsewhere herein. The proximal portion 366 can be a solid wire of circular or elliptical cross-sectional shape. As described elsewhere herein, the proximal portion 366 can be a flattened ribbon having a rectangular cross-sectional shape. The ribbon can be bent into a circular, elliptical, c-shaped or quarter-circular shape or other cross-sectional shapes along an arc. The proximal portion 366 can have any of a variety of cross-sectional shapes, whether or not the lumen extends through the shape, including circular, elliptical, C-shaped, D-shaped or other shapes. In some embodiments, the proximal portion 366 is a hypotube having a D-shape, so that it is flat facing the inside and circular facing the outside. The circular side of the proximal portion 366 can be shaped to engage with the corresponding circular inner surface of the sheath 400. The hypotube can have a lubricating coating, such as PTFE. The hypotube can have an inner diameter of approximately 0.021", an outer diameter of approximately 0.0275", and an overall length of approximately 94 cm, which provides the catheter advancement element 300 with a working length of approximately 143 cm. Including the proximal hub 375, the catheter advancement element 300 can have an overall length of approximately 149 cm. In some embodiments, the hypotube can be a tapered portion having a length of approximately 100 mm, starting at a thickness of 0.3 mm at the proximal end and ending at a thickness of 0.10 mm to 0.15 mm. In yet other embodiments, the elongated body 360 can be a solid element coupled to the proximal portion 366, the solid element having no guidewire lumen.

[0157] like FIG. 7F to FIG. 7J , the proximal end of the hypotube can be coupled to a proximal hub 375. The proximal hub 375 can be an overmolded component with Luer threads 377 and a Luer taper 378 formed on the interior of the proximal hub 375. The proximal hub 375 can incorporate tabs 364 that provide a user with an easier grip. The proximal hub 375 prevents the catheter advancement element 300 and catheter 200 from advancing beyond the distal tip of the base sheath 400 or guide catheter by limiting insertion into the proximal RHV 434, which provides a critical functional and safety feature for proper operation of the system 10.

[0158] At least a portion of the solid elongated body 360 (e.g., elongated distal tip 346) can be formed of a forgeable material or embedded with or attached to the material, which is thinned down to a smaller size at the distal end. The distal tip 346 can be shaped to a desired angle or shape similar to the way a guide wire can be used. The forgeable length of the elongated body 360 can be at least about 1 cm, 3 cm, 5 cm and up to about 10 cm, 15 cm or longer. In some embodiments, the forgeable length can be about 1%, 2%, 5%, 10%, 20%, 25%, 50% or more of the total length of the elongated body 360. In some embodiments, the catheter advancement element 300 can have a working length of about 140 cm to about 143 cm, and the elongated body 360 can have an insertion length of about 49 cm. The insertion length can be the PEBAX portion of the elongated body 360 of about 49.5 cm. It can be seen that the forgeable length of the elongated body 360 can be between about 0.5 cm and about 25 cm or more. The shape change can be a function of the user manually shaping the forgeable length before insertion, or the tip can be preformed to a specific angle or curve during manufacture. Alternatively, the shape change can be a reversible and actuable shape change, so that the tip is shaped when the user actuates, so that the tip can be used in a straight format until the user expects the shape change. The catheter advancement element 300 can also include a forming mandrel extending through the lumen of the elongated body 360, so that the doctor can shape the distal tip 346 into a desired shape when in use. It can be seen that the formable distal tip 346 can be incorporated into the elongated body 360 with the guidewire lumen.

[0159] It should be understood that, as described above, the elongated body 360 can extend along the entire length of the catheter 200, including the distal lumen portion 222 and the proximal extension 230, or the elongated body 360 can incorporate a proximal portion 366 that is generally aligned side by side with the proximal extension 230 of the catheter 200. The proximal portion 366 of the elongated body 360 can be coaxially or eccentrically positioned with the elongated body 360. The proximal portion 366 of the elongated body 360 can have a lumen extending therethrough. Alternatively, the portion 366 can be a solid rod or ribbon without a lumen.

[0160] Refer again 7A to 7D As with the distal lumen portion 222 of the catheter 200, the elongated body 360 can have one or more radiopaque markers 344 along its length. The size, shape, and location of the one or more markers 344 can vary. The one or more markers 344 can be incorporated along one or more portions of the catheter advancement element 300, such as a tip-to-tip marker, a tip-to-cone marker, an RHV approach marker, a fluorine protection marker, or other markers that provide various information regarding the relative position of the catheter advancement element 300 and its components. In some embodiments and as Figure 7C, the distal region can have a first radiopaque marker 344a, and a second radiopaque marker 344b can be positioned to indicate the boundary between the tapering of the distal tip 346 and the more proximal region of the elongated 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 222, which minimizes the lip at the distal end of the lumen 222 in order to advance through tortuous anatomical structures. In other embodiments, such as where the distal tip 346 is not necessarily tapered but has a change in overall flexibility along its length, the second radiopaque marker 344b can be positioned to indicate an area where the relative flexibility of the elongated body 360 (or the distal tip 346 of the elongated body 360) and the distal end of the lumen 222 is approximately the same. The marker material can be a platinum / iridium band, tungsten, a platinum or tantalum impregnated polymer, or other radiopaque markers that do not affect the flexibility of the distal tip 346 and the elongated body 360. In some embodiments, the radiopaque marker is an extruded PEBAX loaded with tungsten for radiopacity.In some embodiments, the proximal marker band can be about 2.0 mm wide and the distal marker band can be about 2.5 mm wide to provide discernible information about the distal tip 346.

[0161] As mentioned above, the proximal extension 230 of the catheter 200 may include a proximal tab 234 on the proximal end of the proximal extension 230. Similarly, the proximal portion 366 coupled to the elongated body 360 may include a tab 364. Tabs 234, 364 can be configured to be removably and adjustably connected to each other and / or to their corresponding proximal portions. Coupling allows the catheter advancement element 300 to be reversibly connected to the catheter 200 to lock (and unlock) the relative extension of the distal lumen 222 and the elongated body 360. This allows the catheter 200 and the catheter advancement element 300 to advance as a single unit. In the locked configuration, the tab 364 or the proximal portion 366 can engage with the catheter tab 234. In the unlocked configuration, the tab 364 can be disengaged from the catheter tab 234. The tab 364 or proximal end 366 can be attached to the catheter tab 234 in a manner with respect to the relationship of the elongated body 360 and the corresponding section of the catheter 200 that maintains a locked configuration, for example, clicks or locks into the catheter tab 234. It should be understood that the tab 364 can be a proximal hub 375 (such as FIG. 7F to FIG. 7J Features on the hub 375) shown.

[0162] This locking can be achieved by, for example, using a pawl on the tab 364 that snaps into place in a recess formed in the catheter tab 234, or vice versa. For example, the tab 234 of the catheter 200 can form a ring having a central opening extending through it. The tab 364 of the body 360 can have an annular pawl having a center column that is sized to be inserted through the central opening of the tab 234 so that the ring of the tab 234 is received in the annular pawl of the tab 364, which forms a single grasping element for the user to advance and / or withdraw the catheter system through the entry sheath. Tabs 234, 364 can be fixed or can be slidable to accommodate different relative positions between the elongated body 360 and the lumen 222 of the catheter 200. In some embodiments, the proximal end of the proximal extension 230 of the catheter 200 may include a coupling feature 334 configured to receive the proximal end 366 of the catheter advancement element 300, such as a clip, clamp, c-shaped element, or other connector (see Figure 2A ). The coupling feature 334 can be configured to snap together with the proximal portion 366 by means of 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, greater level of force is required to remove the proximal portion 366 from the clip of the tab 234. However, when the proximal portion 366 is inserted into the coupling feature 334, the catheter advancement element 300 and the catheter 200 can still be slidably adjusted relative to each other along the longitudinal axis of the system. The amount of force required to slidably adjust the relative position of the two components can be such that unintentional adjustment is avoided, and the relative position can be maintained during use, but the position can be adjusted upon conscious modification. It should be understood that the configuration of the coupling between the proximal portion 366 of the catheter advancement element 300 and the proximal extension 360 of the catheter 200 can vary. However, in general, the coupling is configured to be reversible and adjustable while still providing adequate retention between the two elements in a manner that is relatively user-friendly (e.g., allowing one-handed use) and organizes the proximal ends of the components (e.g., preventing the proximal extension 360 and the proximal end portion 366 from becoming twisted and tangled with each other). It should also be understood that the coupling features 334 configured to prevent tangling and assist in the organization of the proximal end portion can be integrated with the tabs, or can be separate features located along their proximal region.

[0163] The catheter advancement element 300 can be placed in a locking configuration, and the catheter 200 is configured to improve tracking through the tortuous and often diseased blood vessels in acute ischemic stroke. Other configurations are considered here. For example, the elongated body 360 can include one or more ratchets on the outer surface. The ratchets can be located near the proximal region and / or distal region of the elongated body 360. The ratchets are configured to lock together with the corresponding shaped surface features on the inner surface of the lumen portion 222, and the elongated body 360 extends through the surface features. The catheter advancement element 300 and the catheter 200 can incorporate more than a single locking connection point between them. For example, as described elsewhere herein, a coupling feature 334 (such as a clip, a clamp, a c-shaped element or other connector) is configured to keep the proximal extension 230 or the tab 234 of the catheter advancement element 300 and the catheter 200 together.

[0164] In some embodiments, the proximal extension 230 of the catheter 200 can extend beside or within a dedicated channel of the proximal portion 366. The channel can 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 extension 230, so that the proximal extension 230 of the catheter 200 can be received in the channel and smoothly slide along the channel in both directions. Once the catheter 200 and the elongated body 360 are fixed, the combined system (i.e., the catheter 200-catheter advancement element 300) can be delivered to the target site, for example, through the working lumen of the guide sheath 400 described elsewhere herein.

[0165] A catheter advancement element 300 loaded within the lumen of the catheter 200 (whether or not a reinforcement layer is incorporated) can be used to advance the catheter 200 to a distal region of the brain (e.g., at the level of the MCA). The conventional approach to the Circle of Willis is to use a triaxial system that includes a guidewire placed within a conventional microcatheter, which is placed within an intermediate catheter. The entire coaxial system can extend through a base catheter or sheath. The sheath is typically positioned so that the distal tip of the sheath is placed in the high neck carotid artery. Coaxial systems are often advanced in unison until around the distal end of the carotid artery, where conventional coaxial systems must then be advanced in a stepwise manner in separate throws. This is due to two consecutive 180 degree or greater turns (see Figures 1A to 1C ). The first turn is at the level of the petrous to cavernous internal carotid artery. The second turn is at the terminal cavernous carotid artery as it passes through bony elements and reaches the bifurcation of the anterior cerebral artery ACA and the middle cerebral artery MCA. This S-shaped region is referred to herein as the "siphon" or "carotid siphon". The ophthalmic artery arises from the cerebral ICA, which represents a common point for catheters to hang off upon entering the anterior circulation.

[0166] Traditional microcatheter system can be advanced until the anterior circulation by guide wire. Because the inner diameter of traditional microcatheter is significantly larger than the outer diameter of the guide wire through which it advances, a lip can be formed on the distal region of the system, which may be stuck on these side branches during passing through the siphon. Thus, traditional microcatheter system (i.e., guide wire, microcatheter and intermediate conduit) never advances through the two bends of the carotid siphon in a single smooth pass to reach the distal target site. On the contrary, the bend of the carotid siphon is turned one by one in the step-by-step advancement technique. For example, in order to pass through the carotid siphon, traditional microcatheter is kept fixed while the guide wire is advanced a first distance (i.e., the first turn through the siphon) alone. Then, the guide wire is kept fixed while the traditional microcatheter is advanced through the first turn alone by the guide wire. Then, traditional microcatheter and guide wire are kept fixed while the intermediate conduit is advanced through the first turn alone by the microcatheter and guide wire. This process is repeated so as to pass through the second turn of the siphon, which is generally considered to be a more challenging turn to the cerebral blood vessels. The microcatheter and intermediate catheter are held stationary while the guidewire is advanced alone a second distance (i.e., through the second turn of the siphon). The guidewire and interventional catheter are then held stationary while the microcatheter is advanced alone through the second turn via the guidewire. The guidewire and microcatheter are then held stationary while the interventional catheter is advanced alone through the second turn. This multi-stage step-by-step process is a time-consuming process that requires multiple people to perform multiple manual changes to the components. For example, two hands hold the components and push them over each other, which forces the user to hold the steps as described above. A step-by-step procedure is required because the stepped transitions between these components (e.g., guidewire, microcatheter, and intermediate catheter) make advancement too challenging.

[0167] In contrast, the catheter 200 and catheter advancement element 300 eliminate this multi-stage stepwise component advancement procedure across the siphon into the distal site. The catheter 200 and catheter advancement element 300 can be advanced as a single unit through the two turns of the carotid siphon CS. The two turns can be passed through in a single smooth pass or throw to reach the target in the cerebral blood vessels without gradually adjusting their relative extensions and not relying on the traditional stepwise advancement technique described above for traditional microcatheters. The catheter 200 with the catheter advancement element 300 extending through it allows the user to advance them consistently from the first bend of the siphon through the second bend in the same relative position, beyond the terminal cavernous carotid artery, into the ACA and MCA. Importantly, the advancement of the two components can be performed in a single smooth movement through the two bends without any change in the position of the hand.

[0168] The catheter advancing element 300 can be juxtaposed relative to the catheter 200, which provides the best relative extension between the two components for single smooth advancement. The catheter advancing element 300 can be positioned to pass the lumen of the catheter 200 so that its distal tip 346 extends beyond the distal end of the catheter 200. The distal tip 346 of the catheter advancing element 300 eliminates the stepped transition between the inner member and the outer catheter 200, thereby avoiding the problem of being stuck on the branch vessels in the vascular region, so that the catheter 200 can easily pass through the multiple angled turns of the carotid siphon CS. For example, as described elsewhere herein, the best relative extension can be that the distal tip 346 of the elongated body 360 extends distally at the distal end of the catheter 200. The length of the distal tip 346 extending to the distal end of the distal end can be between 0.5cm and about 3cm. This juxtaposition can be the locking engagement with the mechanical element, or simply by the user two components are kept together to carry out.

[0169] The components can be advanced with the guidewire, advanced over a pre-positioned guidewire, or advanced without any guidewire at all. In some embodiments, the guidewire can be preassembled with the catheter advancement element 300 and the catheter 200 so that the guidewire extends through the lumen of the catheter advancement element 300, which is loaded by means of the lumen of the catheter 200, all prior to insertion into the patient. The preassembled components can be inserted into the sheath 400 simultaneously and advanced together up through the bend of the carotid siphon.

[0170] The optimal relative extension of catheter 200 and catheter advancing element 300 may additionally be based on the staggering of material transitions. Fig.111 is a schematic diagram illustrating the approximate locations of material transitions in catheter advancing element 300 and the approximate locations of material transitions in catheter 200. For example, catheter advancing element 300 may include proximal portion 366, which may be a hypotube having a hardness of approximately 72D. Proximal portion 366 transitions to a region of material hardness of approximately 55D at location 1101a, which transitions to a region of material hardness of approximately 35D at location 1101b, which transitions to a region of material hardness of 35D at location 1101c. Similarly, catheter 200 may include proximal extension 230 that is a stainless steel band. The proximal extension 230 transitions to a region of 72D hardness at position 1103a, which transitions to a region of 55D hardness at position 1103b, which transitions to a region of about 40D material hardness at position 1103c, which transitions to a region of about 35D material hardness at position 1103d, which transitions to a region of 25D material hardness at position 1103e, which transitions to a region of about 85A material hardness at position 1103f, which transitions to a region of about 80A material hardness at position 1103g. The distal-most region of the catheter advancing element 300 can be formed of Tecothane having a material hardness of about 62A. Position 1101 of the catheter advancing element 300 and position 1103 of the catheter 200 can be staggered so that the positions are offset from each other. It should be understood that more or fewer material transitions can exist within the catheter advancing element and the catheter.

[0171] The catheter 200 and the catheter advancement element 300 can be preassembled during manufacture so that the optimal length of the catheter advancement element 300 extends to the distal end and / or the material transition is staggered at the distal end of the catheter 200. The optimal extension length can extend the entire length of the tapered distal tip of the catheter advancement element 300 to the distal end of the catheter 200, so that the uniform outer diameter of the catheter advancement element 300 is roughly aligned with the distal end of the catheter 200. This can cause the maximum outer diameter of the elongated body 360 to be roughly aligned 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 at the distal end of the lumen of the catheter 200. This relative structure provides an optimal structure for advancing through tortuous blood vessels, in which the lip at the distal end of the system will cause the greatest difficulty. This optimal preassembled structure can be maintained by a coupler, which is configured to engage with both the proximal extension 230 of the catheter 200 and the proximal end 366 of the catheter advancement element 300. The coupler can be used during surgery as described elsewhere herein. Alternatively, the coupler can be removed prior to surgery.

[0172] Fig.12An embodiment of a coupler 1201 that is configured to be removed prior to surgery is illustrated. The coupler 1201 can be a temporary coupler that is configured to engage the catheter 200 and the catheter advancement element 300 only during manufacturing and / or storage. In some embodiments, the coupler 1201 can be a disk with an adhesive material layer on one side. The coupler 1201 is configured to capture the proximal extension 230 of the catheter 200 and the proximal portion 366 of the catheter advancement element 300, and maintain an optimal pre-assembled extension structure. The coupler 1201 can be easily torn off from the proximal extension 230 and the proximal portion 366 without leaving any residue. The coupler 1201 can be a disk of a plastic material such as polyimide. The hemispheres of the disk are designed to fold over themselves until the bonding sides of each hemisphere engage each other, thereby capturing the hypotubes of the proximal extension 230 and the proximal end 366 of the catheter 200 and the catheter advancement element 300 respectively along the equator of the disk. The disk can include a pair of notches 1203 near the equator so that the overall shape of the disk is bilobed. The disk can include a first circular leaf 1202a on one side of the pair of notches 1203 and a second circular leaf 1202b on the opposite side of the pair of notches 1203, each of the first and second leaves 1202a, 1202b having a matching shape. The hypotube can be captured along the equator of the disk between the first and second leaves 1202a, 1202b, which are folded over each other so that their bonding sides can capture the hypotube. The apex of each notch 1203 is aligned with the equator of the disk, and each notch can include a cutout or notch extension 1205 extending toward the center of the disk. The apex of each notch 1203 cooperates with the notch extension 1205 to assist in starting tearing when the catheter system is ready for use, which creates a stress concentration tearing position. The notch extension 1205 helps guide the tearing direction. Thus, the coupler 1201 engages with both the hypotube proximal extension 230 of the catheter 200 and the hypotube proximal body 330 of the catheter advancement element 300, and the hypotube proximal body 330 is inserted through the lumen of the catheter 200. The coupled engagement allows the two parts that are engaged with each other to be easily inserted into the wrapping hoop while maintaining the optimal relative extension of the parts. The coupler 1201 avoids getting stuck on the wrapping hoop due to the lack of a rounded smooth surface and a stuck edge. Before using the catheter system 100, the user can remove the catheter 200 / catheter advancement element 300 from the wrapping hoop. The coupler 1201 can be torn off from the hypotube by the user pulling the leaves 1202a, 1202b folded above that adhere to each other. Thereby, the entire coupler 1201 is removed from the hypotube without leaving any residue on the hypotube.The system is immediately ready for insertion with optimal pre-assembled relative extension.

[0173] The dimensions of couplers 1201 are such that they provide adequate engagement with the hypotube, locking them together and maintaining relative extension to not be so great as to negatively impact storage within the wrapping hoop. The disc of coupler 1201 can have a diameter of about 0.75" to about 1". The disc can be thinner, such as between about 0.0005" to about 0.0015" thick polyimide. In some embodiments, the polyimide disc is about 0.001" thick. One side of the disc can include a layer of an adhesive, such as a silicone adhesive. The adhesive can be about 0.0015" thick. Each side of recess 1203 can have a length 1 extending between the outer perimeter of the disc and the apex of recess 1203. The length can be about 0.200" long. The sides can form an angle θ relative to each other, the angle being between about 50 and 70 degrees, preferably about 60 degrees.

[0174] It should be appreciated that the catheter and catheter advancing element may be releasably pre-wrapped in a locked position according to any of a variety of methods (eg, shrink wrap and other known methods).

[0175] Material

[0176] One or more components of the catheters described herein may include or be made of various materials, including one or more of the following materials: metals, metal alloys, polymers, metal-polymer composites, ceramics, hydrophilic polymers, polyacrylamides, polyethers, polyamides, polyethylene, polyurethanes, their copolymers, polyvinyl chloride (PVC), PEO, PEO-impregnated polyurethanes (such as Hydrothane, Tecophilic polyurethane, Tecothane, PEO soft block polyurethanes blended with Tecoflex, thermoplastic starch, PVP and combinations thereof, etc.), or other suitable materials.

[0177] Some examples of suitable metals and metal alloys include: stainless steels, such as 304V, 304L, and 316LV stainless steels; mild steels; nickel-titanium alloys, such as linear elastic and / or superelastic nickel-titanium alloys; other nickel alloys, such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 (such as 625), UNS: N06022 (such as C- )、UNS:N10276(such as ),other alloys, etc.), nickel-copper alloys (e.g., UNS: N04400 (such as 400、NICKEL 400, 400, etc.), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 (such as MP35- etc.)), nickel-molybdenum alloys (such as UNS: N10665 (such as ALLOY ), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten alloys or tungsten alloys, etc.; cobalt-chromium alloys; cobalt-chromium alloys (for example, UNS: R30003 (such as etc.); platinum-rich stainless steel; titanium; combinations thereof; etc.; or any other suitable material as described elsewhere herein.

[0178] The lining material of the catheter described herein may include a low friction polymer, such as PTFE (polytetrafluoroethylene) or FEP (fluorinated ethylene propylene), PTFE having a polyurethane layer (Tecoflex). The reinforcing layer material of the catheter described herein may be included to provide mechanical integrity for applying torque and / or preventing flattening or kinking, the reinforcing layer material such as: metal, including stainless steel, nitinol, nitinol webbing, spiral tape, spiral wire, cut stainless steel, etc.; or rigid polymers such as PEEK. The reinforcing fiber material of the catheter described here may include various high-toughness polymers, such as Kevlar, polyester, meta-aramid, PEEK, single fiber, multi-fiber bundle, high tensile strength polymer, metal or alloy, etc. The outer sheath material of the catheter described here can provide mechanical integrity and can shrink various materials, such as polyethylene, polyurethane, PEBAX, nylon, Tecothane, etc. Other coating materials of the catheter described here include para-xylene, Teflon, silicone, polyimide-polytetrafluoroethylene, etc.

[0179] Embodiments describe catheters and delivery systems and methods for delivering catheters to target anatomical structures. However, although some embodiments are described particularly with respect to delivering catheters to target vessels (such as cerebral vessels) of neurovascular anatomical structures, the embodiments are not so limited, and specific embodiments may also be applicable to other purposes. For example, the catheter may be suitable for delivery to different neuroanatomical structures, such as subclavian arteries, vertebrae, carotid vessels, and coronary anatomical structures or peripheral vascular anatomical structures, to name a few possible applications. It should also be understood that although the system described herein is described as being used to treat a specific condition or pathology, the condition or pathology treated may vary and is not limited. The use of the terms "embolus", "embolic", "thrombus", "occlusion" and the like related to the use of the device treatment target described herein is not intended to be limited. The terms may be used interchangeably, and may include but are not limited to blood clots, bubbles, small fat deposits, or other objects carried to a distant location or formed in a certain position in a blood vessel in the blood flow. The terms may be used interchangeably here to refer to the contents of partial or complete occlusion of blood flow that may cause blood flow through a blood vessel or within a blood vessel.

[0180] In various embodiments, description is made with reference to the accompanying drawings. However, a particular embodiment can be practiced without one or more of these specific details or in combination with other known methods and structures. In the description, in order to provide a thorough understanding of the embodiment, a large number of specific details, such as specific structures, sizes and processes, are set forth. In other cases, in order not to make the description unnecessarily vague, known processes and manufacturing techniques are not particularly described in detail. Throughout this specification, references to "one embodiment", "embodiment", "one embodiment", "embodiment" etc. mean that the specific features, structures, structures or characteristics described are included in at least one embodiment or embodiment. Thus, the appearance of phrases "one embodiment", "embodiment", "one embodiment", "embodiment" etc. in various places throughout this specification does not necessarily refer to the same embodiment or embodiment. In addition, specific features, structures, structures or characteristics can be combined in one or more embodiments in any suitable manner.

[0181] The use of relative terms throughout the description may indicate a relative position or direction. For example, "distal end" may indicate a first direction away from a reference point. Similarly, "proximal end" may indicate a position in a second direction opposite to the first direction. However, such terms are provided to create a relative frame of reference and are not intended to limit the use and orientation of the catheter and / or delivery system to the specific configurations described in the various embodiments.

[0182] Although the specification includes many details, these details should not be interpreted as limitations on the scope of claiming or claiming, but should be interpreted as descriptions of features dedicated to specific embodiments. The specific features described in the specification under the background of a separate embodiment can also be implemented in combination in a single embodiment. On the contrary, the various features described under the background of a single embodiment can also be implemented individually in multiple embodiments or in any suitable sub-combination. Moreover, although the features can be described above as working in a specific combination and even initially claiming protection as such, one or more features from the claimed combination can be cut out from the combination in some cases, and the claimed combination can be dedicated to the variant of the sub-combination or sub-combination. Similarly, although the operation is depicted in the drawings in a specific order, this should not be understood as requiring such operation to perform or perform all illustrated operations in the specific order shown or in a sequential order in order to achieve the desired result. Only some examples and embodiments are disclosed. Changes, modifications and enhancements of the examples and embodiments and other embodiments can be performed based on the disclosed content.

[0183] In the above description and claims, phrases such as "at least one of" or "one or more of" may appear, followed by a connected list of elements or features. The term "and / or" may also appear in a list of two or more elements or features. Unless otherwise implicitly or explicitly denied by the context in which the phrase is used, such phrases are intended to mean any one of the listed elements or features, either independently or in combination with any one of the other listed elements or features. 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 explanations are also intended to be used for 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 each 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".

[0184] Use of the term "based on" above and in the claims is intended to mean "based, at least in part, on" such that unrecited features or elements are also permissible.

Claims

1. A system for performing a medical procedure in an intracranial blood vessel of a patient, the system include: a guide sheath, the guide sheath comprising a lumen extending between a proximal region and a distal region of the guide sheath, the distal region of the guide sheath having an opening communicating with the lumen of the guide sheath; A first catheter, the first catheter being sized to be inserted through the lumen of the introducer sheath, the catheter comprising: a flexible distal lumen portion having a proximal end, a proximal opening, a distal end, a distal opening, and a lumen extending between the proximal opening and the distal opening; and a proximal extension extending proximally from an attachment point adjacent the proximal opening to a tab on a proximal end of the proximal extension, wherein the proximal extension is configured to control movement of the catheter, and wherein at least a portion of the proximal extension has an outer diameter that is smaller than an outer diameter of the flexible distal lumen portion; and Wherein, the tab is positioned relative to the proximal opening of the flexible distal tubular lumen to prevent over-insertion of the first catheter relative to the guide sheath and maintain the proximal opening in the lumen of the guide sheath while allowing the distal end of the flexible distal tubular lumen to reach the intracranial blood vessels.

2. The system according to claim 1, in, The distal lumen has a length between the proximal end and the distal end that is less than a length of the introducer sheath and forms an overlap region when the first catheter is extended through the opening of the introducer sheath.

3. The system according to claim 2, in, The tab ensures that a minimum length of the overlap region is achieved to create a seal between the first catheter and the introducer sheath when suction is applied and / or fluid is injected through the introducer sheath.

4. The system according to claim 3, in, The seal is sufficient to withstand pressures from 300 mmHg up to about 700 mmHg.

5. The system according to claim 2, in, The introducer sheath is between 6 Fr and 8 Fr and seals with the outer diameter of the first catheter, wherein the difference between the outer diameter of the first catheter and the inner diameter of the introducer sheath is between 0.001" and 0.004".

6. The system according to claim 1, in, A continuous aspiration lumen is formed extending from a proximal region of the introducer sheath to a distal opening of the first catheter.

7. The system according to claim 1, in, The tab is dimensioned to abut against a portion of the introducer sheath, thereby preventing further distal extension of the catheter through the introducer sheath.

8. The system according to claim 1, in, The tabs serve as gripping features.

9. The system of claim 1 further comprising a second conduit include: a flexible distal lumen portion having a proximal end, a proximal opening, a distal end, and a lumen extending between the proximal end and the distal end; and a proximal extension extending proximally from an attachment point adjacent to the proximal opening, wherein the flexibility of the proximal extension is less than the flexibility of the flexible distal lumen portion, and the proximal extension is configured to control movement of the catheter, and wherein at least a portion of the proximal extension proximal to the attachment point has an outer diameter that is smaller than an outer diameter of the flexible distal lumen portion proximal to the attachment point, and The proximal extension of the second catheter includes a tab positioned relative to the distal opening of the flexible distal lumen portion to prevent over-insertion of the second catheter relative to the guide sheath and the first catheter.

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