Methods and devices for transcarotid access

Abstract

The present invention relates to methods and devices for transcarotid access. An arterial access sheath for introducing an interventional device into an artery is disclosed. The arterial access sheath includes an elongated body and an inner cavity located in the elongated body, the elongated body is sized and shaped to be introduced into the common carotid artery through the carotid artery at an access site in the neck, the inner cavity having a proximal opening in a proximal region of the elongated body and a distal opening in a distal region of the elongated body. The inner cavity provides a passage for introducing an interventional device into the common carotid artery when the elongated body is located in the common carotid artery. The elongated body has a proximal segment and a distal-most segment that is more flexible than the proximal segment. The ratio of the entire length of the distal-most segment to the total length of the sheath body is one-tenth to one-half of the total length of the sheath body.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of August 31, 2015, application number 201580047474.4, and invention name “Method and device for transcarotid access”.

[0002] Citation of priority documents

[0003] No. 14 / 575,199, filed on December 18, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS,” which is a continuation of U.S. patent application serial number 14 / 537,316, filed on November 10, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS,” which claims priority to U.S. provisional application serial number 62 / 046,112, filed on September 4, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS,” and to U.S. provisional application serial number 62 / 046,112, filed on September 4, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS,” and to U.S. provisional application serial number 62 / 046,112, filed on November 4, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS,” and to U.S. provisional application serial number 62 / 046,112, filed on September 4, 2014, entitled “METHODS AND DEVICES FOR TRANSCAROTID ACCESS" is a patent application filed on July 24, 2008. Priority is claimed to the above filing dates and the entirety of each patent application is incorporated herein by reference. Technical Field

[0004] The present disclosure generally relates to medical methods, systems and devices for performing intravascular interventions. More specifically, the present disclosure relates to methods and systems for directly accessing the carotid artery to perform interventional procedures in the treatment of vascular disease and other vascular-related diseases. Background Art

[0005] Interventional procedures are performed to treat vascular disease, such as vascular stenosis, occlusion, aneurysm or fistula. Interventional procedures are also used to perform surgery on organs or tissue objects that can be accessed via blood vessels, such as denervation or ablation of tissue to intervene in nerve conduction, vascular embolization to limit blood flow to tumors or other tissues, and delivery of drugs, contrast agents or other agents to intravascular or extravascular objects for therapeutic or diagnostic purposes. Interventional procedures are typically divided into several categories: coronary, neurovascular and peripheral vascular. Most procedures are performed in the arterial system via an arterial access site.

[0006] Methods for obtaining arterial access to perform these procedures are well established and fall into two broad categories: percutaneous access and surgical cut-down. Most interventional procedures employ percutaneous access. For this access method, a needle puncture is made from the skin through the subcutaneous tissue and muscle layer to the vessel wall and into the vessel itself. Vascular ultrasound is often used to image the vessel and surrounding tissue and facilitates accurate insertion of the needle into the vessel. Depending on the size of the artery and the access device, the method will be different, for example, the Seldinger technique or modified Seldinger technique involves placing a sheath guidewire in the vessel with the aid of a needle. Typically, the sheath guidewire is 0.035" or 0.038". In some cases, micropuncture or microentry techniques are used, based on which the vessel is initially entered through a small needle and then dilated through a 4F microperforated catheter for placement of the sheath guidewire. Once the guidewire is placed, the access sheath and sheath dilator are inserted into the artery over the guidewire. In other cases, such as where the radial artery is being used as the access site, a smaller sheath guidewire, such as a 0.018" guidewire, is used with the initial needle puncture. The dilator of the radial access sheath is designed to accommodate this smaller size guidewire so that the access sheath and dilator can be inserted into the artery along the 0.018" guidewire.

[0007] In surgical incision, a skin incision is made and the tissue is cut to the level of the target artery. This method is usually used when the operation requires a large access device, the puncture entry is risky to the blood vessel and / or there is a possibility of unreliable closure of the access site at the end of the operation. Depending on the size of the artery and the access device, a blade is used to form an incision in the vessel wall, or the vessel wall is directly pierced by an access needle, and the access needle is penetrated by a sheath guide wire. Micropuncture technology can also be used to penetrate the sheath guide wire. As mentioned above, the access sheath and sheath dilator are inserted into the artery along the sheath guide wire. Once the access sheath is in place, the dilator and sheath guide wire are removed. The device can now be introduced into the artery via the access sheath and moved forward to the target site using standard interventional techniques and fluoroscopy to perform the operation.

[0008] Access to the target site is accomplished from an arterial access site that is easily accessible from the skin. Typically, the femoral artery is both relatively large and relatively shallow, and is easily closed at the completion of the procedure using direct compression or one of a variety of vascular closure devices. Therefore, intravascular devices are specifically designed for this femoral artery access site. However, the femoral artery and its surrounding areas are sometimes pathological, making it difficult or impossible to safely enter from this site or introduce the device into the blood vessel. In addition, the treatment target site may be a considerable distance from the femoral artery access point, requiring the device to be quite long and bulky. In addition, reaching the target site from the femoral artery access point may involve traversing a tortuous and / or diseased artery laterally, which increases time and surgical risk. For these reasons, alternative access sites are sometimes used. These alternative access sites include the radial artery, the brachial artery, and the axillary artery. However, these access sites are not necessarily ideal because they involve smaller arteries and may also include tortuous sections, and there is also a certain distance between the access site and the target site.

[0009] Some exemplary problems existing in the prior art

[0010] In some cases, the ideal access site is the carotid artery. For example, procedures to treat disease at the carotid bifurcation and internal carotid artery are fairly close to this access site. Procedures within the intracranial and cerebral arteries are also closer to this access site than the femoral artery. This artery is also larger than some of the alternative access arteries noted above (the common carotid artery is typically 6 to 10 mm in diameter, and the radial artery is 2 to 3 mm in diameter).

[0011] Since most of the access devices used in interventional surgery are designed for femoral artery access, these devices are not ideal for alternative carotid artery access in terms of length and mechanical properties. This makes the operation more cumbersome and in some cases, if a device designed for femoral artery access is used in a carotid artery access operation, the risk is greater. For example, in some operations, such as in an operation involving placing a stent at the carotid bifurcation, it is desirable to keep the distal end of the access sheath below or away from the carotid bifurcation. For patients with low bifurcation, short neck or deep carotid artery, the angle at which the sheath enters the artery (relative to the longitudinal axis of the artery) is very steep relative to the longitudinal axis of the artery, that is, it is more inclined to be vertical rather than parallel relative to the longitudinal axis of the artery. This steep angle increases the difficulty and risk of sheath insertion and device insertion through the sheath. In these operations, there is also the risk of sheath displacement because only a minimum length of sheath can be inserted. In the case of femoral or radial artery access, the sheath is typically inserted into the artery until the hub of the sheath, so that the sheath position is very reliable and parallel to the artery, so that the problem of steep insertion angle and sheath displacement will not occur in the femoral artery range.

[0012] In other procedures, such as those requiring cerebral vascular access, it is desirable to position the sheath tip up to and possibly including the petrous portion of the internal carotid artery. Conventional access sheaths and sheath dilators are not flexible enough to be safely positioned at this site.

[0013] Furthermore, radiation exposure may be a problem for the operator's hands used for procedures utilizing a transcarotid access site if the working area is close to the access site. Summary of the invention

[0014] There is a need for a system of devices that optimizes ease and safety of direct arterial access into the common carotid artery. There is also a need for a system of devices that minimizes radiation exposure to the operator. There is also a need for methods for safely and easily accessing the carotid artery to perform peripheral vascular and neurovascular interventional procedures.

[0015] Disclosed are methods and devices for achieving safe, rapid, and relatively short and direct transcarotid access to arterial vessels for the treatment of coronary heart disease, peripheral vascular and neurovascular diseases. The devices and related methods include transcarotid access devices, guide catheters, catheters and guidewires specifically for reaching target anatomical tissues via transcarotid access sites. Also included in the present disclosure are kits of various combinations of these devices for facilitating various types of transcarotid interventional procedures.

[0016] In one aspect, a system is disclosed for accessing a device for the carotid artery via direct puncture of the carotid artery wall, comprising a sheath guidewire, an arterial access sheath, and a sheath dilator, wherein the arterial access sheath and the sheath dilator are sized and configured to be inserted directly into the common carotid artery in combination along the sheath guidewire, and wherein the sheath has an inner lumen and a proximal port such that the inner lumen provides a passage for insertion of an interventional device into the carotid artery via the proximal port.

[0017] In another aspect, a system for accessing a carotid artery further comprises an access needle, an access guidewire, and an access cannula, all sized and configured to insert the sheath guidewire into the carotid artery wall so that an arterial access sheath and dilator may be placed either percutaneously or via surgical incision.

[0018] In another aspect, a method for treating coronary artery disease, peripheral vascular or neurovascular disease is disclosed, comprising: forming a puncture in a wall of a carotid artery; positioning an arterial access sheath within the artery through the puncture; and treating a target site using a treatment device.

[0019] In another aspect, an arterial access sheath for introducing an interventional device into an artery is disclosed. The arterial access sheath includes an elongated body and an inner cavity located in the elongated body, the elongated body is sized and shaped to be introduced into the common carotid artery through the carotid artery at an entry site in the neck, the inner cavity having a proximal opening in the proximal region of the elongated body and a distal opening in the distal region of the elongated body. The inner cavity provides a passage for introducing an interventional device into the common carotid artery when the elongated body is located in the common carotid artery. The elongated body has a proximal segment and a distal-most segment that is more flexible than the proximal segment. The ratio of the total length of the distal-most segment to the total length of the sheath body is one-tenth to one-half of the total length of the sheath body.

[0020] In another aspect, a system for introducing an interventional device into a carotid artery is disclosed, the system comprising: an arterial access sheath suitable for introducing a catheter into the artery, the arterial access sheath comprising a sheath body sized and shaped to be introduced into the common carotid artery via a carotid access site, the sheath body defining an inner cavity that provides a passage for introducing the catheter into the common carotid artery when the sheath body is located in the common carotid artery; an elongated first dilator positionable within the inner cavity of the sheath body, the first dilator having a tapered shape sized and shaped to dilate the needle puncture site to a larger diameter for inserting the arterial access sheath into the artery A distal end, the first dilator has an inner cavity to allow the dilator to be inserted into the artery along the sheath guidewire, wherein at least a portion of the first dilator has a first bending stiffness, wherein the arterial access sheath and the first dilator can be introduced into the common carotid artery together; an elongated second dilator positionable in the inner cavity of the sheath body, the second dilator having a tapered distal end, the second dilator having an inner cavity to allow the second dilator to be inserted into the artery along the guidewire, wherein the second dilator has a distal region having a second bending stiffness that is smaller than the first bending stiffness of the first dilator.

[0021] In the above system, the first dilator has a distal section that is more flexible than a proximal section of the first dilator to accommodate a steeper angle of insertion into the artery.

[0022] In the above system, the length of the distal section of the first dilator is 2 to 5 cm.

[0023] In the above system, the distal section of the first dilator is 20% to 50% more flexible than the proximal section of the first dilator.

[0024] In the above system, the distal region of the second dilator is more flexible than the distal section of the first dilator.

[0025] In the above system, the length of the distal region of the second dilator is 2 to 5 cm.

[0026] In the above system, the distal region of the second dilator is 20% to 50% more flexible than the proximal region of the second dilator.

[0027] In the above system, the second dilator has a mid-portion that provides a smooth transition in stiffness between a proximal region of the second dilator and a distal region of the second dilator.

[0028] In the above system, the distal region of the first dilator has a force between 50 and 100 N-mm 2 The bending stiffness of the distal region of the second dilator is within the range of 5 to 15 N-mm 2 flexural stiffness within the range of.

[0029] The above system further comprising a radiopaque tip marker on at least one of the first dilator and the second dilator.

[0030] In the above system, the lumen of the second dilator has a diameter that is smaller than a diameter of the lumen of the first dilator.

[0031] In the above system, the lumen of the first dilator accommodates a guidewire having a diameter of 0.035 to 0.038 inches and the lumen of the second dilator accommodates a guidewire having a diameter of 0.014 to 0.018 inches.

[0032] In the above system, a proximal region of at least one of the first dilator and the second dilator includes a hub with a side opening that provides access to the lumen of the corresponding dilator to allow a guidewire to be inserted into or removed from the lumen of the corresponding dilator.

[0033] In the above system, the hub includes a sleeve that moves between a first position covering the side opening and a second position not covering the side opening.

[0034] In the above system, the second dilator is a two-part dilator formed by an outer dilator and one or more inner dilators slidably attached to the outer dilator in a coaxial arrangement.

[0035] In the above system, the outer dilator accommodates a guidewire having a diameter of 0.035 to 0.038 inches and the inner dilator accommodates a guidewire having a diameter of 0.014 to 0.018 inches.

[0036] In the above system, the inner dilator and the outer dilator include proximal hubs that interlock to lock the inner dilator and the outer dilator to each other.

[0037] In the above system, at least one of the inner dilators has an angled tip that is angled to the longitudinal axis of the corresponding dilator.

[0038] In the above system, the sheath body has a proximal section and a distal-most section that is more flexible than the proximal section, and wherein the ratio of the entire length of the distal-most section to the total length of the sheath body is one tenth to one half of the total length of the sheath body.

[0039] In the above system, the sheath body has a proximal section and a distal-most section that is more flexible than the proximal section, and wherein the length of the distal-most section is 2.5 to 5 cm and the length of the entire sheath body is 20 to 30 cm.

[0040] In the above system, the sheath body has a proximal segment and a distal-most segment that is more flexible than the proximal segment and a transition segment between the flexible distal-most segment and the proximal segment, wherein the length of the distal-most segment is 2.5 to 5 cm, the length of the transition segment is 2 to 10 cm, and the length of the entire sheath body is 20 to 30 cm.

[0041] In the above system, at least one of the first dilator and the second dilator is configured to lock onto the arterial access sheath when seated within the lumen of the arterial access sheath.

[0042] Other features and advantages will become apparent from the following description of various embodiments illustrating, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Initial access to the system via the carotid artery is shown.

[0044] Figure 2 The transcarotid access sheath system is shown.

[0045] Figure 3 Components of a transcarotid access system are shown being used to access the carotid artery for carotid surgery.

[0046] Figure 4 An access sheath of a transcarotid access system is shown being used to access the internal carotid artery for intracranial or neurovascular surgery.

[0047] Figure 5 An embodiment of an arterial access sheath is shown.

[0048] Figure 6 and 7 The distal region of the arterial access sheath is shown.

[0049] Figures 8 to 11b An embodiment of an arterial access sheath is shown.

[0050] Fig.12 An embodiment of a dilator is shown.

[0051] Fig.13 and 14 An enlarged view of the proximal region of the dilator is shown.

[0052] Fig.15 and 16 A two-part dilator embodiment is shown.

[0053] Fig.17 The distal region of the dilator is shown with two guidewire lumens.

[0054] Fig.18 Show Fig.17 Cross-sectional view of the distal region of . DETAILED DESCRIPTION

[0055] Methods, systems, and devices for accessing and treating a blood vessel via a transcarotid access point in the carotid region are disclosed.

[0056] Figure 1 A first embodiment of a transcarotid initial access system 100 of a device for establishing initial access to a carotid artery to enable introduction of a guidewire into the carotid artery is shown. Initial access to the carotid artery occurs at an access site located in the patient's neck, such as in the area of ​​the patient's carotid artery. The device of the transcarotid initial access system 100 is particularly suitable for directly accessing the carotid artery through the wall of the common carotid artery.

[0057] like Figure 1 As shown, the transcarotid initial access system 100 includes an access needle 120, an access guidewire 140, and a micropuncture cannula 160. The access needle 120, the access guidewire 140, and the micropuncture cannula 160 are all suitable for introduction into the carotid artery via carotid puncture, as further described below. The carotid puncture can be performed, for example, percutaneously or via surgical incision. Embodiments of the initial access system 100 can be adjusted for one or another puncture method as further described below.

[0058] After establishing access to the carotid artery using the initial access system 100, an access sheath can be inserted into the carotid artery at the access site, wherein the access sheath can be part of a transcarotid access sheath system. Figure 2A first embodiment of a transcarotid access sheath system 200 of a device for inserting an access sheath into a carotid artery along a sheath guidewire is shown. When inserted into the carotid artery, the access sheath enables or allows at least one interventional device to be introduced into the carotid artery via the inner lumen of the access sheath for the purpose of performing an interventional procedure on the vascular region. The transcarotid access sheath system 200 includes an access sheath 220, a sheath dilator 260, and a sheath guidewire 300. The access sheath 220, the sheath dilator 260, and the sheath guidewire 300 are all suitable for introduction into the carotid artery via a carotid puncture, as further described below. The carotid puncture can be performed percutaneously or via a surgical incision. Embodiments of the system 200 can be adjusted for one or other puncture methods as further described below.

[0059] In one embodiment, some or all of the components of the transcarotid initial access system 100 and the transcarotid access sheath system 200 can be combined into a transcarotid access system kit, such as by combining the components into a single package, container, or collection of containers bundled together.

[0060] Figure 3 An access sheath 220 is shown being used to access a common carotid artery 310 for carotid stenting. The access sheath 220 is inserted into the common carotid artery 310 via a surgical incision 315. As further described below, the access sheath 220 has a lumen with openings at the proximal and distal ends or regions of the access sheath 220. With the distal portion of the access sheath 220 within the carotid artery and the proximal portion outside the patient's body, the lumen provides a pathway for inserting an interventional device into the artery.

[0061] Figure 4 The access sheath 200 of the transcarotid access system for intracranial vascular or neurovascular surgery is shown being used to access the internal carotid artery 405 for intracranial or neurovascular surgery. The arterial access sheath 200 is inserted into the common carotid artery 310 via percutaneous puncture. Once inserted into the common carotid artery 310, the distal tip of the access sheath 220 is advanced into the internal carotid artery ICA 320 and upward (relative to the distal cervical or petrous ICA 405) toward or beyond the distal cervical or petrous ICA 405. Figure 4 The perforation in the

[0062] Figure 3 and 4 Both show that the arterial access sheath 220 is being advanced upward through the patient's neck toward the patient's brain. In another embodiment, the arterial access sheath 220 can be downward (relative to the patient's heart) toward the patient's heart, such as toward the aorta, for example. Figure 3-4U.S. Patent No. 8,545,552, entitled “Systems and Methods for Transcatheter Aortic Valve Treatment,” describes an exemplary method for inserting an access sheath directly into the carotid artery and advancing an interventional device toward the aorta and ultimately the aortic valve.

[0063] Arterial access sheath

[0064] Refer to Figure 2 , one embodiment of the transcarotid access sheath 220 includes an elongated sheath body 222 and a proximal adapter 224 at the proximal end of the elongated sheath body 222 of the access sheath 220. The elongated sheath body 222 is the portion of the arterial access sheath 220 that is sized and shaped to be inserted into an artery, and wherein at least a portion of the elongated sheath body is actually inserted into the artery during surgery. The proximal adapter 224 includes a hemostatic valve 226 and an elongated flushing line 228 having an inner lumen that communicates with the inner lumen of the sheath body 222. The proximal adapter 224 may have a larger diameter or cross-sectional size than the sheath body 222. The hemostatic valve 226 is in communication with the inner lumen of the sheath body 222 to allow a device to be introduced therein while preventing or minimizing blood loss through the inner lumen during surgery. In one embodiment, the hemostatic valve 226 is a static sealing type passive valve. In an alternative embodiment of the arterial access sheath 220 (in Figure 5 ), the hemostasis valve 226 is an adjustable opening valve such as a Tuohy-Borst valve 227 or a rotating hemostasis valve (RHV). Alternatively, the access sheath 220 may terminate at the proximal end of a female Luer adapter to which a separate hemostasis valve member may be attached, the hemostasis valve being a passive sealing valve, a Tuohy-Borst valve, or a rotating hemostasis valve (RHV).

[0065] The elongated sheath body 222 of the arterial access sheath 220 has a diameter suitable for or specifically optimized to provide arterial access to the carotid artery. In one embodiment, the elongated sheath body 222 is in the size range of 5 to 9 Fr, or alternatively in the inner diameter range of 0.072 inches to 0.126 inches. In one embodiment, the elongated sheath body 222 is a 6 or 7 Fr sheath. In embodiments where the sheath is also used for pumping or reverse flow or for introducing larger devices, the sheath is an 8 Fr sheath.

[0066] The elongated sheath body 222 of the arterial access sheath 220 has a length from the proximal adapter 224 to the distal end of the elongated sheath body 222 suitable for reaching a treatment site located in or toward the brain relative to an arterial access site in the common carotid artery CCA. For example, in order to enter the carotid bifurcation or the proximal internal carotid artery ICA from the CCA access site, the elongated sheath body 222 of the access sheath 220 (i.e., the portion that can be inserted into the artery) can have a length in the range of 7 to 15 cm. In one embodiment, the elongated sheath body 222 has a length in the range of 10-12 cm. In order to enter the same target site from the femoral artery access site, a typical access sheath must be between 80 cm and 110 cm, or a guide catheter must be inserted through the arterial access sheath and moved forward to the target site. The guide catheter passing through the access sheath occupies the lumen area and thus constrains the size of the device that can be introduced into the target site. Therefore, an access sheath that allows an interventional device to reach the target site without using a guide catheter is superior to an access sheath that requires the use of a guide catheter to allow the interventional device to reach the target site.

[0067] Alternatively, in order to position the distal tip of the elongated sheath body 222 more distally relative to the access site, for example to perform intracranial or neurovascular surgery from the CCA access site, the elongated sheath body 222 of the access sheath 220 may have a length in the range of 10 cm to 30 cm, depending on the desired target location of the distal tip of the sheath. For example, if the target location is the distal CCA or the proximal ICA, the elongated sheath body 222 may be in the range of 10 cm to 15 cm. If the desired target location is the mid-to-distal cervical, petrous, or cavernous segments of the ICA, the elongated sheath body 222 may be in the range of 15 to 30 cm.

[0068] Alternatively, the arterial access sheath 220 is constructed or adapted for a treatment site or target location proximal to the arterial access site (i.e., toward the aorta) when the access site is within the common carotid artery. For example, the treatment site can be a proximal region of the CCA, CCA orifice, ascending or descending aorta or aortic arch, aortic valve, coronary arteries, or other peripheral arteries. For these target locations, the appropriate length of the elongated sheath body 222 depends on the distance from the target site to the access site. In this configuration, the elongated sheath body 222 is placed through the arterial access site and oriented toward the lower part of the aorta.

[0069] The access sheath 220 may also include a radiopaque end marker 230. In one example, the radiopaque end marker is a metal band embedded near the distal end of the sheath body 222 of the access sheath 220, such as a platinum-iridium alloy. Alternatively, the access sheath end material may be a separate radiopaque material, such as a barium polymer or a tungsten polymer mixture. The sheath end itself is constructed so that when the access sheath 220 is assembled using a sheath dilator 260 to form a sheath assembly, the sheath assembly can be smoothly inserted along the sheath guidewire 300 through the arterial perforation with minimal resistance. In one embodiment, the elongated sheath body 222 of the access sheath 220 has a smooth or hydrophilic coating to reduce friction during insertion into the artery. In one embodiment, the distal coating is limited to the farthest 0.5 to 3 cm of the elongated sheath body 222, so that it is conducive to insertion without sacrificing the safety of the sheath at the perforation site or the ability of the operator to firmly hold the sheath during insertion. In an alternative embodiment, the sheath is not coated.

[0070] refer to Figure 2 In one embodiment, the arterial access sheath 220 has features that help secure the sheath during surgery. For example, the access sheath 220 may have suture eyelets 234 or one or more ribs 236 molded into or otherwise attached to the adapter 224 (located at the proximal end of the elongated sheath body 222) to allow the operator to sew the sheath hub to the patient.

[0071] For a sheath suitable for insertion into the common carotid artery for the purpose of accessing the carotid bifurcation, the length of the elongated sheath body 222 may be in the range of 7 to 15 cm, typically 10 to 12 cm. The inner diameter is typically in the range of 5 Fr (1 Fr = 0.33 mm) to 10 Fr, typically 6 to 8 Fr. For a sheath suitable for insertion into the middle or distal internal carotid artery via the common carotid artery for the purpose of accessing the intracranial or cerebral vessels, the length of the elongated sheath body 222 may be in the range of 10 to 30 cm, typically 15 to 25 cm. The inner diameter is typically in the range of 5 Fr (1 Fr = 0.33 mm) to 10 Fr, typically 5 to 6 Fr.

[0072] Particularly when the sheath is introduced above the clavicle but below the carotid bifurcation by transcarotid approach, it is desirable that the elongated sheath body 222 be flexible while maintaining the hoop strength to resist twisting or buckling. This is particularly important in surgeries where the amount of sheath insertion into the artery is limited and there is a steep insertion angle as in transcarotid access in patients with deep carotid arteries and / or short necks. In these situations, there is a tendency for the end of the sheath body to be oriented toward the posterior wall of the artery due to the rigidity of the sheath. This causes the risk of injury due to the insertion of the sheath body itself or a device such as a guide wire inserted into the artery through the sheath. Alternatively, the distal region of the sheath body may be placed in a distal carotid artery including one or more bends, such as the rocky ICA. Therefore, it is desirable that the sheath body 222 be constructed so that it can bend when inserted into the artery without twisting. In one embodiment, the sheath body 222 is circumferentially reinforced, such as by a stainless steel or nitinol braid, a spiral ribbon, a spiral wire, a cut stainless steel or nitinol hypotube, a cut rigid polymer, etc. and an inner liner so that the reinforcement structure is sandwiched between the outer shell layer and the inner liner. The inner liner can be a low friction material such as PTFE. The outer shell can be one or more materials in the group of materials including Pebax, thermoplastic polyurethane, or nylon.

[0073] In one embodiment, the flexibility of the sheath body 222 can vary along its length. This change in flexibility can be achieved in various ways. For example, the hardness and / or material of the outer shell can vary in various sections. Alternatively, the reinforcing structure or material can vary along the length of the sheath body. In one embodiment, the distal-most section of the sheath body 222 is more flexible than the rest of the sheath body. For example, the bending stiffness of the distal-most section is one-third to one-tenth of the bending stiffness of the rest of the sheath body 222. In one embodiment, the distal-most section has a bending stiffness of 50 to 300 N-mm 2 The bending stiffness (E*I) of the sheath body 222 is in the range of 500 to 1500 N-mm 2 , where E is the elastic modulus and I is the area moment of inertia of the device. For a sheath configured for a CCA access site, the flexible distal-most segment comprises a significant portion of the sheath body 222 that can be expressed as a ratio. In one embodiment, the length of the flexible distal-most segment accounts for a ratio of the total length of the sheath body 222 that is at least one-tenth and at most one-half of the length of the entire sheath body 222.

[0074] In some cases, the arterial access sheath is configured to enter the carotid bifurcation or the proximal internal carotid artery ICA from the CCA access site. In this case, an embodiment of the sheath body 222 has a distal-most section 223 of 3 to 4 cm and the entire sheath body 222 is 10 to 12 cm. In this embodiment, the ratio of the length of the flexible distal-most section to the total length of the sheath body 222 is about one-quarter to one-half of the total length of the sheath body 222. In another embodiment, there is a transition section 225 between the distal-most flexible section and the proximal section 231, wherein there are one or more sections with different flexibility between the distal-most section and the rest of the sheath shell. In this embodiment, the distal-most section is 2 to 4 cm, the transition section is 1 to 2 cm, and the entire sheath body 222 is 10 to 12 cm, or expressed as a ratio, the distal-most flexible section and the transition section together form at least one-quarter and at most one-half of the total length of the sheath body.

[0075] In some cases, the sheath body 222 of the arterial access sheath is configured to be inserted further into the internal carotid artery relative to the arterial access position, and can be inserted into the intracranial section of the internal carotid artery. For example, the most distal section 223 of the elongated sheath body 222 is 2.5 to 5 cm and the length of the entire sheath body 222 is 20 to 30 cm. In the present embodiment, the length of the most distal section of the flexibility accounts for one-tenth to one-quarter of the total length of the sheath body of the entire sheath body 222. In another embodiment, there is a transition section 225 between the most distal flexible section and the proximal section 231, wherein the most distal section is 2.5 to 5 cm, the transition section is 2 to 10 cm, and the entire sheath body 222 is 20 to 30 cm. In the present embodiment, the most distal flexible section and the transition section together form at least one-sixth and at most one-half of the sheath body.

[0076] Other embodiments are adapted to reduce, minimize or eliminate the risk of damage to the artery due to the distal-most sheath tip facing and contacting the posterior arterial wall. In some embodiments, the sheath has a structure configured to center the sheath body tip within the lumen of the artery so that the longitudinal axis of the distal region of the sheath body is generally parallel to the longitudinal axis or central axis of the vessel lumen. Figure 6 In the illustrated embodiment, the sheath alignment feature is an inflatable or expandable bumper, such as a balloon 608, located on the outer wall of the arterial access sheath 220. The balloon 608 can expand in size to apply a force on the inside of the artery to contact and push the elongated body 222 of the arterial access sheath away from the arterial wall.

[0077] In another embodiment, the sheath alignment feature is one or more mechanical structures on the sheath body that can be actuated to extend outward from the sheath tip. In one embodiment, the sheath body 222 is configured to be inserted into the artery in such a way that a specific edge of the arterial access site is against the posterior wall of the artery. In this embodiment, the sheath alignment feature only needs to extend outward in one direction relative to the longitudinal axis of the sheath body 222 to lift or push the sheath tip away from the posterior wall of the artery. For example, Figure 6 As shown, the inflatable buffer 608 is a blister on one side of the sheath body. In another example, the mechanical feature extends only on one side of the sheath body.

[0078] In another embodiment, at least a portion of the sheath body 222 is preformed so that after the sheath is inserted, the end is further aligned with the longitudinal axis of the vessel, even if the angle of the sheath insertion is steeper. In this embodiment, when the dilator is assembled with the sheath during insertion of the sheath along the sheath guidewire, the sheath body is generally straight, but once the dilator and guidewire are removed, the distal-most section of the sheath body is in a curved or angled shape. In one embodiment, the sheath body is formed so that, when measured from the main axis of the sheath body, the distal-most 0.5 to 1 cm section is at an angle of 10 to 30 degrees, with a radius of curvature of approximately 0.5". In order to maintain the curved or angled shape of the sheath body after it has been straightened during insertion, the sheath can be heat set in an angled or curved shape during manufacturing. Alternatively, the reinforcement structure can be composed of nitinol and heat formed into a curved or angled shape during manufacturing. Alternatively, another spring element can be added to the sheath body, such as adding a strip of spring steel or nitinol having a suitable shape to the reinforcement layer of the sheath.

[0079] In an alternative embodiment, there are methods where it is desirable to minimize resistance to flow through an access sheath, such as described in US Pat. Nos. 7,998,104 to Chang and 8,157,760 to Criado, both of which are incorporated herein by reference. Figure 7An embodiment of a sheath body 222 is shown wherein the sheath body has a stepped or tapered configuration having a distal region 705 of reduced diameter (wherein the reduced diameter is relative to the remainder of the sheath). The distal region 705 of the stepped sheath can be sized for insertion into a carotid artery, which typically has an inner diameter in the range of 0.065 inches to 0.115 inches, with the remainder of the proximal region of the sheath having a larger outer diameter and lumen diameter, wherein the inner diameter is typically in the range of 0.110 inches to 0.135 inches. The larger lumen diameter of the remainder of the sheath body minimizes flow resistance through the sheath. In one embodiment, the reduced diameter distal segment 705 has a length of approximately 2 cm to 4 cm. The relatively short length of the reduced diameter distal segment 705 allows the segment to be positioned within the common carotid artery CCA via a transcarotid approach with a reduced risk that the distal end of the sheath body will contact bifurcation B. In addition, the reduced diameter section also allows the size of the arteriotomy for introducing the sheath into the artery to be reduced while minimizing the impact on the level of flow resistance. In addition, the reduced diameter distal section can be more flexible and therefore can better conform to the lumen of the blood vessel.

[0080] In some cases, such as in procedures where distal emboli / thrombi may form, it may be desirable for the sheath body 222 to also occlude the artery in which it is positioned. In these cases, occluding the artery stops antegrade vascular flow within the artery and thereby reduces the risk that distal emboli may cause neurological symptoms such as TIA or stroke. Figure 8 An embodiment of an arterial access sheath 220 is shown with an inflatable balloon 805 on the distal region, which is inflated by means of tubing 810 connecting the internal inflation lumen in the sheath body 222 to a stopcock 229, which in turn can be connected to an inflation device. In this embodiment, there is also a Y-arm 815 that can be connected to a passive or active pumping source to further reduce the risk of distal emboli.

[0081] In some cases, it may be desirable to move the hemostasis valve away from the distal end of the sheath while maintaining the length of the sheath that is insertable into the sheath body 222. The present embodiment is configured to move the operator's hands, and indeed his or her entire body, away from the target site and therefore away from the image intensifier used to fluorescently image the target site, thereby reducing the user's radiation exposure during surgery. Essentially, this extends the portion of the arterial access sheath 220 that is outside the body. The inner and outer diameters of this portion may be greater than the sheath body 222. In situations where the outer diameter of the catheter inserted into the sheath approaches the inner diameter of the sheath body, the annular space available for flow in the lumen is limited. Minimizing the sheath body length therefore helps minimize flow resistance, such as during flushing of the sheath with saline or contrast solution or during pumping or backflow out of the sheath. In situations such as Fig. 9In the illustrated embodiment, the arterial access sheath 220 has an insertable elongated sheath body 222 (i.e., a portion configured to be inserted into an artery) and a proximal extension 905. In one embodiment, the sheath body 222 has an inner diameter of approximately 0.087" and an outer diameter of approximately 0.104", corresponding to a 6Fr sheath size, and the proximal extension has an inner diameter of approximately 0.100" to 0.125" and an outer diameter of approximately 0.150" to 0.175". In another embodiment, the sheath body 222 has an inner diameter of approximately 0.113" and an outer diameter of approximately 0.136", corresponding to an 8Fr sheath size, and the proximal extension has an inner diameter of approximately 0.125" and an outer diameter of approximately 0.175". In yet another embodiment, the sheath body 222 is stepped, having a smaller diameter distal section 705 to further alleviate flow restriction, such as Figure 7 As shown. In one embodiment, the length of the proximal extension 905 is suitable for significantly reducing the radiation exposure of the user during the transcarotid access procedure. For example, the proximal extension 905 is between 10 cm and 25 cm, or between 15 cm and 20 cm. Alternatively, the proximal extension 905 has a length configured to provide a distance of about 30 cm to 60 cm between the hemostasis valve 226 and the distal end of the sheath body, depending on the insertable length of the access sheath. The connector structure 915 can connect the elongated sheath body 222 to the proximal extension 905. In this embodiment, the connector structure 915 may include suture eyelets 920 and / or ribs 925 to help secure the access sheath to the patient. In one embodiment, the hemostasis valve 2266 is a static sealing passive valve. In an alternative embodiment, the hemostasis valve 226 is an adjustable opening valve such as a Tuohy-Borst valve 227 or a rotating hemostasis valve (RHV). Alternatively, the proximal extension may terminate at a proximal end in a female Luer adapter to which a separate hemostasis valve member may be attached, which may be a passive sealing valve, a Tuohy-Borst valve, or a rotary hemostasis valve (RHV).

[0082] Typically, a vascular closure device requires an arterial access sheath with a maximum distance between the distal end of the sheath body and the proximal structure of the hemostatic valve of about 15 cm, where the sheath body 222 is about 11 cm and the remaining 4 cm includes the length of the proximal hemostatic valve; therefore, if the access sheath has a distance of more than 15 cm, it is desirable to remove the proximal extension 905 at the end of the procedure. In one embodiment, the proximal extension 905 can be removed in such a way that hemostasis is maintained after removal. For example, the hemostatic valve is built into the connector 915 between the sheath body 222 and the proximal extension 905. The hemostatic valve opens when the proximal extension 905 is attached to allow fluid communication and insertion of the device, but prevents blood from flowing out of the sheath when the proximal extension 905 is removed. After the procedure is completed, the proximal extension 905 can be removed, thereby reducing the distance between the proximal structure of the hemostatic valve and the sheath end from more than 15 cm to less than 15 cm and thereby allowing the vascular closure device to be used in conjunction with the access sheath 220 to close the access site.

[0083] In some procedures, it may be desirable to connect a low resistance (large bore) flow line or shunt to the access sheath, such as described in U.S. Pat. No. 7,998,104 to Chang and U.S. Pat. No. 8,157,760 to Criado, both of which are incorporated herein by reference. Fig.10 The arterial sheath embodiment shown has a flow line 1005 with an inner cavity of a Y-shaped arm 1015 leading to a connector 915. The flow line has an inner cavity that is fluidly connected to the inner cavity in the sheath body. The flow line 1005 can be connected to a low-pressure return site such as a venous return site or a reservoir. The flow line 1005 can also be connected to a pumping source such as a pump or a syringe. In one embodiment, an occluding element, such as an occluding balloon, can also be included on the far end of the sheath body 222. This may be desirable in percutaneous surgery where a blood vessel cannot be occluded by a vascular surgical device such as a vascular hoop or a vascular clamp.

[0084] In some procedures, it may be desirable to limit the amount of sheath body that is inserted into the artery, such as in procedures where the target area is very close to the arterial access site. For example, in stenting of the carotid bifurcation, the sheath tip should be proximal to the treatment site (relative to the access site) so that it does not interfere with stent deployment or access to the diseased area and potentially cause emboli to be shaken loose. Fig.11a and 11bIn the illustrated embodiment of the arterial sheath 220, the sheath stop 1105 is slidably or mounted on the outside of the distal portion of the sheath body. The sheath stop 1105 is shorter than the distal portion of the sheath, thereby effectively shortening the insertable portion of the sheath body 222 by forming a reliable stop at a certain length along the sheath body 222. The sheath stop 1105 can be a tube that is slidably fitted on the sheath body 222 at a length that exposes the distal portion of the sheath body when located on the sheath body 222. The length can be in the range of 2 to 4 cm. More specifically, the length is 2.5 cm. The distal end of the sheath stop 1105 can be angled and oriented so that, when the sheath is inserted into the artery when the blood vessel is inserted into the artery, the angle is flush with the blood vessel and acts as a stop against the arterial wall, such as Fig.11a Alternatively, the distal end of the sheath stopper may be formed as an angled flange 1115 that contacts the arterial wall, such as Fig.11b As shown. Flange 1115 is rounded or has an atraumatic shape to form a more reliable and atraumatic stop against the arterial wall. Sheath stop 1105 can be permanently fixed to the arterial sheath, for example, the proximal end of the sheath stop can be attached to the connector 915 of the arterial access sheath. Alternatively, sheath stop 1105 can be removed from the arterial access sheath 220 by the user, so it can be selectively used in surgery. In this case, sheath stop 1105 can have a locking feature structure on the proximal portion that engages with a corresponding locking feature structure on the connector 915, such as a groove or recess on the proximal sheath stop that engages with a protrusion on the connector. Other locking feature structures can also be used.

[0085] In conditions where insertion of the sheath body is limited to between 2 and 3 cm, and particularly when the sheath body is inserted at a steep angle, the sheath may conform to a bayonet shape when secured to the patient. For example, the bayonet shape may include a first portion extending along a first axis and a second portion extending along a second axis axially offset from the first axis and / or not parallel to the first axis. The elasticity of the sheath body causes this shape to apply force to the vessel at the insertion site and increases the tendency of the sheath to dislodge from the vessel if it is not properly secured. In order to reduce stress on the vessel, the sheath stop may be pre-formed into a curved or bayonet shape so that the stress of the sheath body when bent is distributed to the sheath stop rather than the vessel. The sheath stop may be made of a resilient but bendable material or include a spring element such as a stainless steel or nitinol wire or strip so that when the dilator is inserted into the sheath and sheath stop assembly, the sheath is relatively straight, but when the dilator is removed, the sheath stop is in a pre-curved shape to reduce the force distributed by the sheath on the vessel wall. Alternatively, the sheath stop may be made of a malleable material or include a malleable element such as a bendable wire or ribbon so that it can be reshaped to a desired curvature after sheath insertion to reduce stress imparted by the sheath on the vessel wall.

[0086] Sheath Dilator

[0087] Refer to Figure 2 , the sheath dilator 260 is a component of the transcarotid access sheath system 200. The sheath dilator 260 is an elongated body that is inserted into the artery and enables the access sheath 220 to be smoothly inserted along the sheath guidewire 300 through the puncture site in the arterial wall. Therefore, the distal end of the dilator 260 is generally tapered / conical to allow the dilator to be inserted into the artery along the sheath guidewire 300 and to expand the needle puncture site to a larger diameter for the insertion of the access sheath 220 itself. To accommodate these functions, the dilator 260 has a tapered end 268 with a total angle (relative to the longitudinal axis of the dilator) generally between 6 degrees and 12 degrees, with a rounded leading edge. The sheath dilator is typically locked on the access sheath when assembled for insertion into the artery. For example, the proximal hub 264 of the sheath dilator 260 is configured to snap into or on a corresponding structure on the hemostatic valve 226 of the arterial access sheath 220. The lumen of dilator 260 accommodates sheath guidewire 300 with an inner diameter between 0.037" and 0.041", depending on, for example, the sheath guidewire size.

[0088] For the transcarotid access sheath system 200, it may be desirable to make the distal section of the sheath dilator 260 more flexible to correspond with the increased flexibility section of the access sheath 220. For example, the distal 2 to 5 cm of the sheath dilator 260 may be 20% to 50% more flexible than the proximal portion of the sheath dilator 260. This embodiment will allow the inserted sheath and dilator to accommodate steeper insertion angles (enabling smoother insertion over the guidewire while still maintaining the columnar support of the dilator), as is the case in transcarotid access procedures. It is desirable that the columnar support provide the insertion force required to expand the puncture site and insert the access sheath.

[0089] For some transcarotid access sheath systems, it may be desirable to also use a smaller diameter access guidewire (e.g., in the range of 0.014" to 0.018" in diameter) to introduce the sheath and dilator into the artery. In the present embodiment, the sheath dilator tapered end 268 is configured to provide a smooth transition from the smaller guidewire size to the access sheath. In one variation, the sheath guidewire is 0.018" and the dilator lumen is in the range of 0.020" to 0.022". In another variation, the sheath guidewire is 0.014" and the dilator lumen is in the range of 0.016" to 0.018". The taper is similarly modified, such as being longer in length to accommodate the taper from the smaller diameter to the inner diameter of the access sheath, or may include two taper angles to provide a smooth transition from the smaller diameter guidewire to the access sheath without excessively extending the overall length of the taper.

[0090] In some operations, it is desirable to position the distal end of the sheath body 222 of the arterial access sheath 220 in the middle to distal vertebral segment, petrous segment or cavernous sinus segment of the ICA as described above. These segments have a curvature generally greater than 90 degrees. It may be desirable that the sheath dilator has a softer and longer taper so that these bends can be easily manipulated without the risk of damaging the artery. However, in order to insert the sheath through the arterial perforation, the dilator ideally has a certain rigidity and taper to provide expansion force. In one embodiment, the transarterial access sheath system 200 is provided or included in a kit including two or more tapered dilators 260A and 260B. The first tapered dilator 260A is used in conjunction with the arterial access device to enter the artery, and is therefore sized and constructed in a manner similar to that of a standard introducer sheath dilator. Exemplary materials that can be used for the tapered dilator include, for example, high-density polyethylene, 72D Pebax, 90D Pebax, or materials with comparable rigidity and smoothness. The second tapered dilator 260B of the kit can be used with an arterial access device with a softer distal section or a distal section with lower bending stiffness than the distal section of the first tapered dilator. That is, the second dilator has a distal region that is softer, more flexible, or more easily articulated or bent than the corresponding distal region of the first dilator. The distal region of the second dilator is therefore easier to bend than the corresponding distal region of the first dilator. In one embodiment, the distal section of the first dilator 260A has a bending stiffness of 50 to 100 N-mm 2 The bending stiffness of the distal section of the second dilator 260B is within the range of 5 to 15 N-mm 2 flexural stiffness within the range of.

[0091] A second dilator 260B (which has a distal section with lower bending stiffness) can be exchanged with the initial first dilator so that the arterial access device can be inserted into the internal carotid artery and around the bend in the artery without causing unnecessary force or trauma to the vessel due to the softer distal section of the second dilator. The distal section of the softer second dilator can be, for example, 35 or 40D Pebax, with the proximal portion made of, for example, 72D Pebax. One or more intermediate sections may be included on the second dilator to provide a smooth transition between the softer distal section and the stiffer proximal section. In one embodiment, one or both dilators may have a radiopaque end marker to make the position of the dilator end visible during fluoroscopy. In one variation, the radiopaque marker is a tungsten-containing Pebax or polyurethane section that is heat welded to the distal end of the dilator. Other radiopaque materials may be similarly used to form a radiopaque marker at the distal end.

[0092] To facilitate exchange of a first dilator for a second dilator, one or both dilators may be configured such that the distal section of the dilator is comprised of a tapered single lumen tube, but the proximal portion of the dilator and any adapter on the proximal end have side openings. Fig.12 An example of a dilator 1205 formed of an elongated member sized and shaped to be inserted into an artery and a proximal hub 1210 is shown. The dilator has a side opening 1215, such as a slot, extending along at least a portion of the length of the dilator 1205, such as along the elongated body and the proximal hub 1210. In one embodiment, the side opening 1215 is located only on the proximal region of the dilator 1205 and passes through the proximal hub 1210, although this can vary. The side opening 1215 provides access to the lumen of the dilator 1205, such as inserting a guide wire into the lumen and / or removing a guide wire from the lumen. An annular, movable sleeve 1220 with a slot on one side is located on or near the proximal hub 1210 of the dilator 1205. The sleeve 1220 can move around the longitudinal axis of the hub 1210, such as by rotation, as described below. Note that the distal end of the dilator 1205 has a tapered configuration for dilating tissue.

[0093] Fig.13 An enlarged view of the proximal region of the dilator 1205 is shown. As described above, the dilator 1205 has a side opening 1215 in the form of a groove extending along the length of the dilator 1205 and the proximal hub 1210. The sleeve 1220 is located around the periphery of the dilator and is formed so that it covers at least a portion of the side opening 1215. Thus, the sleeve 1220 can prevent a guidewire located inside the dilator 1205 from exiting the dilator through the side opening 1215. As described above, the sleeve 1220 can rotate relative to the dilator 1205 and the proximal hub 1210. In the illustrated embodiment, the sleeve 1220 can rotate about the longitudinal axis of the dilator 1205, although other types of relative motion are also within the scope of the present disclosure. Fig.14 As shown, sleeve 1220 has a slot 1225 that can be aligned with the side opening 1215. When so aligned, slot 1225 and side opening 1215 together provide an opening for a guide wire to be inserted into or removed from the lumen of dilator 1205. Sleeve 1220 can be Fig.13 The position shown (in which the sleeve covers the side opening 1215) is similar to Fig.14 12. The side opening 1215 is rotated between the positions shown (in which the side opening is exposed due to the alignment of the slot 1225 with the side opening 1215).

[0094] A method of using this embodiment of the access sheath kit is now described. A sheath guidewire, such as a 0.035" guidewire, is inserted into the common carotid artery using a modified Seldinger technique or a micropuncture technique. The distal end of the guidewire can be positioned within the internal carotid artery or the external carotid artery, or stopped within the unbranched common carotid artery. An arterial access sheath with a first, stiffer dilator is inserted into the artery along the 0.035" guidewire. The arterial access sheath is inserted in such a manner that at least 2.5 cm of the sheath body 222 is located within the artery. If additional purchases are desired, the arterial access sheath can be further oriented and oriented within the internal carotid artery. The first dilator is removed while maintaining the arterial access sheath and 0.035" guidewire in place. The side opening 1215 in the proximal portion of the dilator allows the dilator to be removed in a "quick exchange" manner so that the majority of the guidewire outside the access device can be directly grasped during dilator removal. The second dilator is then loaded onto the 0.035" guidewire and inserted into the sheath. Likewise, a dilator with side openings 1215 in the proximal portion of the dilator can be used to allow a 0.035" guidewire to be directly grasped during guidewire insertion in a "rapid exchange" technique. Once the second dilator is fully inserted into the arterial access device, the arterial access sheath of the second dilator with a softer tip is advanced within the internal carotid artery and around the bends within the artery without causing unnecessary force or fear of causing vascular trauma. This configuration allows the arterial access sheath to be placed more distally without sacrificing the ability of the device to be inserted into the artery.

[0095] Alternatively, one or more standard dilators without side openings may be used. If a standard dilator without side openings is used, after the access device is inserted into the artery along the guidewire using the first dilator, the first dilator can be removed along with the guidewire, leaving only the access device in place. The second dilator can be inserted into the arterial access device together with the guidewire preloaded into the central lumen. Once fully inserted, the access device and the second dilator with a softer tip can be advanced distally in the internal carotid artery as described above. In this alternative method, the initial guidewire can be used with both dilators, or can be interchanged with a guidewire with a softer tip when inserted together with a second dilator with a softer tip.

[0096] In some cases, it may be desirable to insert an access sheath system into the carotid artery over a 0.035" guidewire, but then replace the guidewire with a smaller guidewire in the range of 0.014" to 0.018". Because a steep entry angle may be required to enter the carotid artery, it may be desirable to first introduce the access sheath into the CCA using a guidewire that provides good support, such as a 0.035" guidewire. However, once the sheath is in the artery but the user wants to advance it further over the smaller guidewire, it may be desirable to replace the 0.035" guidewire with a smaller guidewire. Alternatively, the user may replace both the dilator and the 0.035" guidewire with a softer dilator and a smaller guidewire in the range of 0.014" to 0.018". Alternatively, the user may wish to position a 0.14" guidewire that he or she will subsequently use to introduce the interventional device while the sheath and dilator are still in place. The dilator can provide access and support for the guidewire and, in the case of a demanding sheath entry angle, can assist in guiding the guidewire away from the posterior wall of the artery so that the guidewire can be safely advanced into the vessel lumen without risk of luminal damage.

[0097] In such Fig.15 In the illustrated embodiment, the sheath dilator 260 is a two-part dilator assembly having an inner dilator 269 and an outer dilator 270 slidably attached to one another in a coaxial arrangement. The two dilators have proximal hubs 264a and 264b. When the two dilators are assembled together, the two hubs 264a and 264b have a feature structure that allows the two dilators to be locked together, such as a snap or threaded fit, so that the two dilators can be manipulated as a whole. In one embodiment, the inner dilator 269 has a proximal hub 264b including a swivel connector having internal threads that engage with external threads on the proximal hub 264a of the outer dilator 270. The inner dilator 269 effectively converts the dilator assembly from a 0.035" or 0.038" guidewire-compatible dilator to a 0.018" or 0.014" guidewire-compatible dilator and extends from the distal end of the outer dilator. Fig.16 In the illustrated embodiment, the inner dilator has an angled tip 276 that is bent or angled relative to the longitudinal axis of the rest of the dilator. In one embodiment, the angle is a 45 degree angle. The angled tip 276 allows the user to more easily introduce a guidewire into one or another branch vessel. The inner dilator may have a Fig.15 tapered, straight end as shown or as Fig.16Angled tip as shown. Alternatively, the inner dilator may have a constant outer diameter leading to the distal end with a rounded leading edge. In one embodiment, the inner dilator has a radiopaque marker 274 at or near the distal tip to assist in visualization of the dilator under fluoroscopy. In one embodiment, the inner dilator is reinforced to make it easier to twist to assist in guiding the angled tip in a particular direction. For example, the dilator may have a spiral or braided reinforcement layer. Once the interventional guidewire is in place, the two-part dilator is removed and the guidewire can then be used to insert the interventional device through the arterial sheath into the artery and advance to the treatment site.

[0098] Fig.17 The alternative embodiment shown allows two separate guidewire sizes to be used with the dilator.This embodiment includes a dilator 1705 having two guidewire lumens extending along the length of the device. Fig.17 The distal end of this embodiment is shown. Fig.18 As seen more clearly in the cross-sectional view of , one lumen 1805 is configured for a 0.035" or 0.038" guidewire, while the other lumen 1815 is for a 0.014" to 0.018" guidewire. In this embodiment, the larger lumen 1805 is centered about the centerline of the cone 268, while the smaller lumen 1815 is offset from the centerline of the cone. In this configuration, the entry sheath is introduced into the artery along the larger guidewire located within the larger lumen 1805. Once positioned, an interventional guidewire can be placed through the second lumen 1815. The larger guidewire and dilator are then removed from the entry sheath and the interventional guidewire can then be used to insert the interventional device into the artery through the arterial sheath and advance it to the treatment site as described above.

[0099] Sheath Guidewire

[0100] The arterial access sheath is typically introduced into the artery over a sheath guidewire having a diameter of 0.035" or 0.038" . The inner diameter and taper length of the distal tip of the dilator are sized to fit such a guidewire. For example, some sheaths used for radial artery access are sized to accommodate a sheath guidewire having a diameter of 0.018" , with the corresponding dilator having a distal tip inner diameter and taper length. The sheath guidewire may have an atraumatic straight, angled, or J-shaped tip. The guidewire smoothly transitions to a stiffer section on the proximal end. This configuration allows the guidewire to be introduced and advanced into the artery atraumatically while allowing the sheath to be supported as the sheath is introduced into the artery over the guidewire. Typically, the transition from the atraumatic tip is 4 to 9 cm in front of the stiffer section. The sheath is typically inserted 15 to 20 cm into the artery so that the stiffer section of the guidewire is at the arterial access site when the sheath is inserted.

[0101] However, in the case of a transcarotid access point, the amount of guidewire that can be inserted before potentially causing damage to the distal vessel is much less than 15 cm. In the case of transcarotid access for arterial stenting or PTA procedures, it is very important to limit the guidewire insertion length to avoid the risk of distal emboli of the sheath guidewire at the carotid patient site. Therefore, it is desirable to provide a guidewire that can provide support for potentially steep sheath entry angles while limiting the insertion length. In one embodiment, a transcarotid sheath guidewire has an atraumatic terminal segment with a very far and short transition before a stiffer segment. For example, a softer terminal segment is 1.5 to 2.5 cm, followed by a transition segment of 3 to 5 cm in length, followed by a stiffer proximal segment, wherein the stiffer proximal segment includes the remainder of the guidewire. .

[0102] The sheath guidewire may have a guidewire marker 318 to help the user determine the position of the end of the guidewire relative to the dilator. For example, there may be a marker on the proximal end of the guidewire corresponding to when the end of the guidewire is about to leave the end of the micro-entry cannula. The marker will provide fast guidewire position feedback to help the user limit the amount of insertion of the guidewire. In another embodiment, the guidewire may include another marker to let the user know that the guidewire has left the distance set by the cannula, such as 5 cm.

[0103] Micro-entry components

[0104] Reference Figure 1 , a micro-entry kit 100 for initial trans-arterial access includes an access needle 120, an access guidewire 140, and a micro-entry cannula 160. The micro-entry cannula 160 includes a body 162 and an inner dilator 168 slidably located within the lumen of the body 162. Typically, for arterial access, the initial needle puncture can use a 21G or 22G access needle, or an 18G needle in the case of using a modified Seldinger technique. For trans-carotid access, it may be desirable to use a smaller needle puncture for access. Carotid puncture access is typically more challenging than femoral puncture access. The carotid artery is a thicker-walled artery, it is surrounded by a tissue sheath called the carotid sheath, and it is not anchored by surrounding muscle tissue, so the initial needle puncture is more difficult and must be completed with greater force on an unstable artery, thereby increasing the risk of misplaced puncture, arterial dissection, or posterior wall puncture. A smaller initial needle puncture, such as a 23G or 24G needle, increases the ease of needle access and reduces these risks. The sheath guidewire should therefore be sized to fit within a smaller needle, such as a 0.016" or 0.014" guidewire. The access needle 120 may include a textured surface on the distal end to make it visible under ultrasound, thereby facilitating ultrasound-guided insertion of the needle into the artery. The needle length may be in the range of 4 cm to 8 cm.

[0105] Similar to the sheath guidewire, the micro-entry guidewire has a transition section from a soft distal tip to a core section that is harder than the distal tip or distal region. Such micro-entry guidewires are typically 0.018" in diameter, with a soft distal section of approximately 1 to 2 cm and a transition zone of 5-6 cm before the harder section. In one embodiment, the transcarotid access guidewire is 0.014" to 0.018" in diameter and has a 1 cm soft section, a 2-3 cm transition zone to bring the harder support section much closer to the distal tip. This will allow the user to provide good support for his micro-entry cannula insertion even with steep entry angles and limited guidewire insertion length.

[0106] Like the sheath guidewire, the micro-entry guidewire may have a guidewire marker 143 to help the user determine the position of the end of the guidewire relative to the microcannula. For example, the marker may correspond to when the end of the guidewire is about to leave the microcannula and be located on the proximal end of the guidewire. The marker will provide fast guidewire position feedback to help the user limit the amount of insertion of the guidewire. In another embodiment, the guidewire may include another marker to let the user know that the guidewire has left the dilator set distance, such as 5cm.

[0107] The micro-entry cannula itself can be configured for transcarotid insertion. Typically, the micro-entry cannula 160 includes a cannula 162 and an inner dilator 168 with a tapered tip. The inner dilator 168 provides a smooth transition between the cannula and the access guidewire. The cannula is sized to receive a 0.035" guidewire, and the inner diameter of the cannula size ranges from 0.038" to 0.042". In one embodiment, the micro-entry cannula 160 is configured for transcarotid access. For example, the dilator of the cannula can be sized for a smaller 0.014" access guidewire 140. In addition, the cannula itself can have depth markings to assist the user in limiting the amount of insertion. In one embodiment, the micro-entry cannula 160 has a radiopaque marker 164 at the distal tip of the cannula 162 to help the user visualize the tip position under fluoroscopy. This is useful, for example, in situations where the user may wish to position the cannula, for example, within the ICA or ECA.

[0108] Example Kits:

[0109] Any or all of the above devices may be provided to the user in kit form such that one or more components of the system are included in a common package or packaged collection.An embodiment of an access sheath kit includes an access sheath, a sheath dilator, and a sheath guidewire all configured for transcarotid access as described above.

[0110] In one embodiment, the microaccess kit includes an access needle, a microaccess guidewire, and a microaccess cannula, and a dilator, wherein the guidewire is 0.014" and the microaccess cannula and dilator are sized to be compatible with the 0.014" guidewire.

[0111] In one embodiment, an access kit includes an access sheath, a sheath dilator, a sheath guidewire, an access needle, a micro access guidewire and a micro access cannula, and a dilator, all configured for transcarotid access.

[0112] In an alternative embodiment, the access guidewire is also used as a sheath guidewire. In this embodiment, the access kit includes an access needle, an access guidewire, an access sheath, and a dilator. The sheath and dilator are inserted into the blood vessel using the access guidewire, thereby avoiding the need to change to a larger sheath guidewire. In this embodiment, the dilator taper length and lumen size are determined to be compatible with a smaller access guidewire. In one embodiment, the access guidewire is 0.018". In an alternative embodiment, the access guidewire is 0.016". In an alternative embodiment, the access guidewire is 0.014".

[0113] Exemplary methods:

[0114] An exemplary method of using the transcarotid access system is now described. In an exemplary transcarotid procedure for treating carotid stenosis, the user first cuts the common carotid artery. The user then inserts the access needle 120 into the common carotid artery at the desired access site. An access guidewire 140 with a taper configured for transcarotid access is inserted through the needle into the common carotid artery and advanced into the CCA. The access needle 120 is removed and a micro-entry cannula 160 is inserted into the CCA along the guidewire 140. The micro-entry cannula is inserted into the desired depth using the markings 166 on the cannula as a guide to prevent over-insertion.

[0115] The user removes the dilator 168 and the guide wire 140 in the cannula, leaving the cannula 162 in place. If necessary, the user performs angiography via the cannula 162. The user then places the sheath guide wire 300 via the cannula, using the guide wire marker 318 to assist in inserting the guide wire to the desired insertion depth. The cannula 162 is removed from the guide wire and the entry sheath 220 and the sheath dilator 260 are inserted into the CCA as a component along the sheath guide wire 300. The sheath stop flange 1115 of the sheath stop 1105 limits the insertion length of the arterial sheath. Once positioned, the dilator 260 and the guide wire 300 are removed. The sheath is then sutured to the patient using the fixing eyelet 234 and / or rib 236. The interventional procedure is then performed by guiding the interventional device to the proximal end of the arterial sheath through the hemostatic valve 226 and to the desired treatment site. During the operation, contrast medium injection can be performed as needed via the flushing arm 228 on the arterial sheath 220.

[0116] Alternatively, the sheath guidewire 300 is placed into the CCA via a single needle puncture using a larger access needle, such as an 18G needle. In this embodiment, an access cannula and access guidewire are not required. This embodiment reduces the number of steps required to access the artery and may be desirable to the user in some situations.

[0117] Alternatively, the sheath dilator is Fig.15 The two-part sheath dilator assembly 260 shown includes an inner dilator 269 and an outer dilator 270. The outer dilator 270 is configured to receive a 0.035" sheath guidewire 300 and provide a smooth transition from the 0.035" guidewire to the entry sheath 220. The inner dilator 269 is configured to receive a smaller guidewire in the range of 0.014" to 0.018" and provide a smooth transition from the smaller guidewire to the outer dilator 270. Once the sheath guidewire is within the CCA, the entry sheath and outer sheath dilator 270 are inserted into the CCA over the 0.035" sheath guidewire 300. The guidewire is then removed and the intrathecal dilator 269 is inserted into the extrathecal dilator. In one embodiment, the intrathecal dilator has a Fig.16 . An interventional 0.014" guidewire is inserted through the intrathecal dilator and guided to the target treatment site using the angled tip to aid in guidewire positioning. Alternatively, the intrathecal dilator has a straight tip and is used to assist in safely positioning the guidewire within the CCA. Once the 0.014" guidewire is positioned at or passed through the target treatment site, the sheath dilator 260 and sheath 0.035" guidewire 300 are then removed and the intervention is performed.

[0118] In an alternative embodiment, the sheath dilator is a dual lumen sheath dilator 1705. In this embodiment, the sheath and dilator are inserted over a sheath guidewire 300, wherein the sheath guidewire is located within the larger lumen 1805 of the dilator 1705. Once the sheath and dilator are in place, an interventional 0.014" guidewire is positioned through the smaller lumen 1815. The dilator provides distal support and maintains the axial position of the sheath tip within the vessel lumen, thereby making advancement of the 0.014" guidewire safer and easier than it might be if the dilator was removed and the sheath tip was at least partially directed toward the posterior wall of the artery. Once the 0.014" guidewire is positioned at or through the target treatment site, the sheath dilator 1705 and sheath 0.035" guidewire are then removed and the intervention is performed.

[0119] In yet another embodiment, it may be desirable to occlude the CCA during intervention to minimize the antegrade flow of emboli. In this embodiment, the occlusion step may be performed via vascular surgery, such as using a vascular hoop, tourniquet, or vascular clamp. In an alternative embodiment, the access sheath 220 has an occlusion element such as an occlusion balloon 250 on the distal end. In this embodiment, the balloon is inflated when the CCA is desired to be occluded. In yet another variation, although the CCA is occluded surgically or by balloon occlusion, it may also be desirable to connect the arterial sheath to the shunt, such as to establish a reverse flow system around the area of ​​the treatment site to minimize distal emboli. In this embodiment, the arterial sheath 220 has a Y-shaped connection to the flow line 256. The flow line can be connected to a return site, such as an external reservoir or a central venous return site such as the femoral vein or internal jugular vein, where the pressure is lower than the arterial pressure, to establish a pressure gradient that causes reverse flow through the shunt. Alternatively, the flow line may be connected to a pumping source such as a pump or syringe.

[0120] In another embodiment, the transcarotid access system is used to perform percutaneous neurointerventional surgery. In this embodiment, the user performs percutaneous puncture of the common carotid artery CCA using the access needle 120 at the desired access site. Ultrasound can be used to accurately determine the appropriate access site and guide needle puncture. The access guide wire 140 is inserted into the common carotid artery through the needle and moved forward into the CCA. The access needle 120 is removed and the micro-access cannula 160 is inserted into the CCA along the guide wire 140. The user removes the cannula dilator 168 and the guide wire 140, thereby leaving the cannula 162 in place. If necessary, the user performs angiography via the cannula 162. The user then places the sheath guide wire 300 via the cannula, using the guide wire marker 318 to assist the desired insertion length. The cannula 162 is removed from the guide wire and the access sheath 220 and the sheath dilator 260 are inserted into the CCA as a component along the sheath guide wire 300.

[0121] Alternatively, a smaller access guidewire 140 is used to position the access sheath 220 and sheath dilator 260 within the CCA. In the present embodiment, the sheath dilator tapered tip 266 has been configured to smoothly transition from the access guidewire 140 to the access sheath 220. In one variation, the access needle is 21G and the access guidewire is 0.018". In another variation, the access needle is 24G and the access guidewire is 0.014". Once the sheath is in place, the guidewire and sheath dilator are removed and the interventional procedure is then performed by guiding the interventional device through the hemostasis valve 226 on the proximal end of the arterial sheath and directing it to the desired treatment site. Contrast injections may be performed as needed during the procedure via the flush arm 228 on the arterial sheath 220.

[0122] Alternatively, it may be desirable to advance the sheath further into the ICA once it is positioned within the CCA, such as the mid-to-distal cervical ICA, the petrous ICA, or beyond. In this embodiment, the sheath dilator may be replaced with a softer sheath dilator so that the sheath may be advanced without damaging the distal ICA. In this embodiment, the softer dilator has a distal radiopaque marker so that the user can easily see the leading edge of the sheath and dilator assembly during positioning of the sheath. Once the sheath is positioned, the dilator and sheath guidewire may be removed and an intervention may be performed. Alternatively, once the sheath is positioned within the CCA, the 0.035" guidewire may be removed and an inner dilator with a smaller guidewire in the range of 0.014" to 0.018" may be inserted into the sheath dilator. The sheath dilator and smaller guidewire assembled with the inner dilator may then be positioned further out of the ICA with reduced risk of vascular trauma.

[0123] In one embodiment, it may be desirable to occlude the CCA or ICA at various stages of the procedure to reduce the chance of distal emboli flowing to the brain. In this embodiment, the CCA or ICA is occluded with the aid of an occlusion balloon 250 on an access sheath 220. It may be desirable to connect the arterial sheath to a shunt, for example to form a reverse flow system around the area of ​​the treatment site to minimize distal emboli. In this embodiment, the arterial sheath 220 has a Y-shaped connection to a flow line 256. The flow line can be connected to a reflux site at a pressure lower than the arterial pressure to form a pressure gradient that causes reverse flow through the shunt. Alternatively, the flow line can be connected to a pumping source such as a pumping pump or a syringe.

[0124] Although this specification contains many details, these details should not be interpreted as a limitation on the scope of the invention for which a patent is claimed or may be claimed, but rather as a description of features specific to a particular embodiment. Certain features described in the context of a separate embodiment in this specification may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. In addition, although the above features are described as working in certain combinations and even initially claiming patent rights, one or more features in the combination claiming patent rights may be separated from the combination in some cases, and the combination claiming patent rights may be directed to a sub-combination or a variation of a sub-combination. Similarly, although operations are depicted in the drawings in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order shown, or to perform all illustrated operations to achieve the desired result.

[0125] Although various methods and apparatus embodiments are described in detail herein with reference to certain variations, it should be understood that other variations, embodiments, methods of use, and combinations thereof are also possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments herein.

Claims

1. An arterial access sheath for introducing an interventional device into an artery, comprising: an elongated sheath body sized and shaped to be introduced through the neck into the common carotid artery at an entry site in the neck; a sheath stop slidably mounted outside the distal portion of the sheath body for effectively shortening the insertable portion of the sheath body by forming a reliable stop at a certain length along the sheath body, the sheath stop having an angled flange at its distal end configured to contact the arterial wall, the flange being rounded or having an atraumatic shape to form a more reliable and atraumatic stop against the arterial wall; a lumen in the sheath body, the lumen having a proximal opening in a proximal region of the sheath body and a distal opening in a distal region of the sheath body, the lumen providing a passage for introducing the interventional device into the common carotid artery when the sheath body is located within the common carotid artery; wherein the sheath body comprises a proximal segment and a distal-most segment which is more flexible than the proximal segment, and wherein the ratio of the total length of the distal-most segment to the total length of the sheath body is one tenth to one half of the total length of the sheath body, and wherein the total length of the sheath body is 20 cm to 30 cm.

2. The sheath of claim 1, wherein: The bending stiffness of the distal-most section is one-third to one-tenth of the bending stiffness of the remainder of the sheath body.

3. The sheath of claim 1, wherein: The distalmost section has a force between 50 and 300 N-mm 2 The bending stiffness (E*I) of the sheath body is in the range of 500 to 1500 N-mm 2 The bending stiffness is within the range of , where E is the elastic modulus and I is the area moment of inertia of the sheath body.

4. The sheath of claim 1, further comprising a transition section between the distal-most section and the proximal section, wherein the flexibility of the transition section is between the flexibility of the distal-most section and the flexibility of the proximal section.

5. The sheath of claim 1, wherein: The ratio of the overall length of the distal-most section to the overall length of the sheath body is between one quarter and one half of the overall length of the sheath body.

6. The sheath of claim 1, wherein: The total length of the sheath body is 20 cm to 30 cm, and wherein the distal-most section is 2.5 cm to 5 cm.

7. The sheath of claim 4, wherein: The total length of the sheath body is 20 cm to 30 cm, the length of the distal-most section is 2.5 cm to 5 cm, and the length of the transition section is 2 cm to 10 cm.

8. The sheath of claim 4, wherein: The distal-most flexible section and the transition section together form at least one quarter and at most one half of the total length of the sheath body.

9. The sheath of claim 4, wherein: The distal-most flexible section and the transition section together form at least one-sixth and at most one-half of the total length of the sheath body.

10. The sheath of claim 1, wherein: The sheath body comprises: Lining; outer shell; A reinforcement structure is sandwiched between the inner liner and the outer shell.

11. The sheath of claim 10, wherein: The flexibility of the reinforcing structure varies along the length of the sheath body.

12. The sheath of claim 10, wherein: The reinforcing structure is a stainless steel braid or a nitinol braid, a spiral ribbon, a spiral wire, a cut stainless steel hypotube or a cut nitinol hypotube, or a cut rigid polymer.

13. The sheath of claim 10, wherein: The outer shell is one or more materials from the group of materials comprising Pebax, thermoplastic polyurethane or nylon.

14. The sheath of claim 10, wherein: The lining comprises a low friction material.

15. The sheath of claim 1, further comprising radiopaque markings on the sheath body.

16. The sheath of claim 1, further comprising a connector structure at a proximal end of the sheath body, and further comprising a proximal extension extending proximally from the connector structure.

17. The sheath of claim 16, wherein: The length of the proximal extension is between 10 cm and 25 cm.

18. The sheath of claim 16, wherein: The length of the proximal extension is between 15 cm and 20 cm.

19. The sheath of claim 16, wherein: The proximal extension has an inner diameter greater than an inner diameter of the sheath body and an outer diameter greater than an outer diameter of the sheath body.

20. The sheath of claim 16, wherein: The connector structure includes suture eyelets.

21. The sheath of claim 16, further comprising a hemostatic valve on the proximal end of the proximal extension.

22. The sheath of claim 16, wherein: The proximal extension is removable from the connector structure, and wherein the connector structure further comprises a hemostatic valve, such that the hemostatic valve is open when the proximal extension is attached to the connector structure but is sealed when the proximal extension is removed from the connector structure.

23. The sheath of claim 1, wherein: The sheath body has a distal section formed in a curved or angled configuration.

24. The sheath of claim 1, further comprising an elongated dilator sized to be positioned within the lumen of the sheath body, wherein the elongated dilator has a distal-most section that is flexible and corresponds to a distal-most section of the sheath body of the sheath.

25. A system for introducing an interventional device into a carotid artery, the system comprising: An arterial access sheath adapted for introducing a catheter into an artery, the arterial access sheath comprising a sheath body sized and shaped to be introduced into a common carotid artery via a carotid access site, the sheath body defining an inner lumen providing a passage for introducing a catheter into the common carotid artery when the sheath body is located within the common carotid artery, the arterial access sheath being coupled to a sheath stop slidably mounted outside a distal portion of the sheath body for effectively shortening an insertable portion of the sheath body by forming a reliable stop at a certain length along the sheath body, the sheath stop having an angled flange at its distal end configured to contact an arterial wall, the flange being rounded or having an atraumatic shape to form a more reliable and atraumatic stop against the arterial wall; an elongated first dilator positionable within the lumen of the sheath body, the first dilator having a tapered distal tip sized and shaped to dilate a needle puncture site to a larger diameter for inserting the arterial access sheath into the artery, the first dilator having an inner lumen to allow the dilator to be inserted into the artery over a sheath guidewire, wherein at least a portion of the first dilator has a first bending stiffness, wherein the arterial access sheath and the first dilator can be co-introduced into the common carotid artery; an elongated second dilator positionable within the lumen of the sheath body, the second dilator having a tapered distal tip, the second dilator having an inner lumen to allow the second dilator to be inserted into an artery over a guidewire, wherein the second dilator has a distal region having a second bending stiffness less than a first bending stiffness of the first dilator; and A flow line is fluidly coupled to the arterial access sheath and is configured to be connected to a reverse flow shunt line to enable reverse flow of blood outwardly from the arterial access sheath via the flow line.

26. The system of claim 25, wherein: The first dilator has a more flexible distal section than a proximal section of the first dilator to accommodate a steeper angle of insertion into the artery.

27. The system of claim 25, wherein: The distal region of the second dilator is more flexible than the distal section of the first dilator.

28. The system of claim 25, wherein: The second dilator has a mid-portion that provides a smooth transition in stiffness between a proximal region of the second dilator and a distal region of the second dilator.

29. The system of any one of claims 25 to 28, wherein: The distal region of the first dilator has a force between 50 and 100 N-mm 2 The bending stiffness of the distal region of the second dilator is within the range of 5 to 15 N-mm 2 flexural stiffness within the range of.

30. The system of claim 25, wherein: The lumen of the second dilator has a diameter that is smaller than a diameter of the lumen of the first dilator.

31. The system of claim 25, wherein: The lumen of the first dilator accommodates a guidewire having a diameter of 0.035 to 0.038 inches and the lumen of the second dilator accommodates a guidewire having a diameter of 0.014 to 0.018 inches.

32. The system of claim 25, wherein: The sheath body has a proximal section and a distal-most section that is more flexible than the proximal section, and wherein the ratio of the entire length of the distal-most section to the total length of the sheath body is one tenth to one half of the total length of the sheath body.

33. The system of claim 25, wherein: At least one of the first dilator and the second dilator is configured to lock onto the arterial access sheath when seated within the lumen of the arterial access sheath.

34. The system of claim 25, wherein: The arterial access sheath includes an inflatable balloon at a distal region configured to be inflated via an inflation line connecting an internal inflation lumen in the sheath body to a stopcock.

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