Vascular conduits to facilitate temporary direct access to blood vessels

Abstract

Methods, devices, and systems according to the present invention establish and facilitate arterial access for interventional procedures such as stenting, angioplasty, grafting, replacement valve therapy, and atherectomy.

Description

[Technical field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to co-pending U.S. Provisional Application No. 63 / 127818, filed December 18, 2020, and U.S. Provisional Application No. 63 / 187759, filed May 12, 2021, the entire contents of each of which are incorporated herein by reference. [Background technology]

[0002] Temporarily accessing a blood vessel such as the common carotid artery (CCA) using an arterial access sheath is an important aspect in various interventional procedures, including transcarotid artery revascularization (TCAR) procedures and other procedures in which an arterial access sheath is inserted directly into the common carotid artery (CCA). To ensure safe insertion of the arterial sheath into the common carotid artery (CCA), the distance between the clavicle and the carotid bifurcation is preferably at least 5 cm. This portion of the common carotid artery (CCA) is also preferably relatively disease-free. Atherosclerosis usually consists of deposits of plaque P in the carotid artery that narrow the junction of the common carotid artery (CCA) with the internal carotid artery (ICA), the artery that supplies blood flow to the brain. Insertion of the arterial sheath at this location may release embolic material when one or more system components contact the plaque deposits. For example, the introducer guidewire, arterial dilator, or arterial sheath may all disrupt the plaque, causing the release of embolic particles. The embolic particles generated can enter the cerebral vasculature and cause neurological consequences such as transient ischemic attacks (TIAs), ischemic strokes, or death. Furthermore, if such stenosis becomes severe, it can obstruct blood flow to the brain, with serious, even fatal, consequences. The shorter the common carotid artery (CCA), the higher the risk of this complication.

[0003] Furthermore, insertion of the arterial sheath into the common carotid artery (CCA) may cause arterial dissection, especially in patients with a CCA that is relatively deep below the skin surface. Also, the insertion angle of the arterial sheath for patients with a deep CCA is generally steeper (e.g., 50-80 degrees to the horizontal). Also, a steeper insertion angle between the arterial sheath and the sheath expander used to advance the arterial sheath through the vessel wall may increase the risk of arterial dissection or perforation of the posterior arterial wall.

[0004] Additionally, some carotid artery patients or procedures (e.g., procedures in short / deep vessels, diseased patients, dissected patients, patients with scar tissue, etc.) may require a larger inner diameter sheath or delivery system and therefore a larger entry point into the carotid artery. Such patients and procedures would benefit from the use of a larger diameter conduit (e.g., as part of a large diameter delivery system). Additionally, the conduits described herein can improve surgical outcomes and reduce patient discomfort. For example, sutures such as purse string sutures can be used to attach the conduit to the access site during left ventricular apical access. Use of conduits such as those described herein stabilizes tissue at the access site, thus improving surgical outcomes and reducing patient discomfort. Summary of the Invention

[0005] Solutions to these and other problems in the art are provided herein, among other things. Aspects of the inventive subject matter relate, among other things, to systems for accessing an artery via a transcarotid approach. Related systems and methods are also provided.

[0006] In accordance with certain aspects of the present subject matter, a system for accessing an artery via a transcarotid approach is disclosed comprising: an arterial access device having a distal connector, a lumen and a hemostatic valve disposed on an opposing side of the lumen from the distal connector; a conduit having a lumen extending between a proximal end and a distal end and a coupler located at the proximal end, the distal end configured for end-to-side surgical anastomosis to a blood vessel, the distal connector of the arterial access device configured to operably couple to the coupler at the proximal end of the conduit to fluidly connect the lumen of the arterial access device to the lumen of the conduit.

[0007] In variations, one or more of the following features may be included in any feasible combination. For example, in some embodiments, the conduit is a flexible tubular structure formed of a biotextile. In some embodiments, the conduit is a vascular graft. In some embodiments, the vascular graft is formed of a substrate selected from the group consisting of polyethylene terephthalate, polyester, nylon, expanded polytetrafluoroethylene, heparin-bonded ePTFE, hooded PTFE, ring-reinforced ePTFE, and a hybrid weave of nylon and ePTFE. In some embodiments, the lumen of the conduit has a diameter greater than about 2 mm and less than or equal to about 10 mm. In some embodiments, the lumen of the conduit has a diameter greater than or equal to about 6 mm and less than or equal to about 16 mm. In some embodiments, the lumen of the conduit has a diameter greater than or equal to about 8 mm and less than or equal to about 10 mm. In some embodiments, the arterial access device further comprises a distal sheath coupled to the distal connector and extending distally therefrom, the distal sheath comprising a sheath lumen. In some embodiments, the outer size of the sheath lumen is 7 Fr or more and 10 Fr or less. In some embodiments, the outer size of the sheath lumen is 12 Fr or more and 36 Fr or less. In some embodiments, the outer size of the sheath lumen is 14 Fr or more and 20 Fr or less. In some embodiments, the length of the conduit from the proximal end to the distal end is longer than the length of the distal sheath, such that the distal end of the distal sheath remains proximal to the distal end of the conduit within the lumen of the conduit as the distal sheath extends through the lumen of the conduit. In some embodiments, the length of the conduit is 5 cm or more and 30 cm or less, and the length of the distal sheath is 4 cm or more and 29 cm or less. In some embodiments, the blood vessel is a common carotid artery, a femoral artery, a radial artery, a brachial artery, an ulnar artery, or a subclavian artery.

[0008] In some embodiments, the system further comprises a shunt fluidly connected to the arterial access device, the shunt providing a pathway for blood to flow from the arterial access device to a return site. In some embodiments, the system further comprises a flow control assembly coupled to the shunt and configured to regulate blood flow through the shunt. In some embodiments, the system further comprises a suction device coupled to a port on the shunt. In some embodiments, the suction device is a syringe or a pump. In some embodiments, the system further comprises a distal adapter coupled to the distal sheath and extending distally therefrom.

[0009] In a related aspect, another system for accessing an artery via a transcarotid approach is provided that includes a conduit having a lumen extending between a proximal end and a distal end, the distal end configured for surgical end-to-side anastomosis to a blood vessel, a coupler disposed at the proximal end of the conduit, and a shunt fluidly connected to the coupler, the lumen of the conduit being connected to a lumen of the shunt to provide a pathway for blood to flow from the conduit through the shunt to a return site.

[0010] In variations, one or more of the following features may be included in any feasible combination. For example, in some embodiments, the system further comprises a port in fluid communication with the shunt, the port configured to connect an aspiration device to the shunt, and a distal connector of an arterial access device configured to operably couple to the coupler at the proximal end of the conduit to fluidly connect a lumen of the arterial access device to the lumen of the conduit. In some embodiments, the conduit is a flexible tubular structure formed of a biotextile. In some embodiments, the conduit is a vascular graft. In some embodiments, the conduit provides an access port for procedures in the innominate artery ostium, the aorta, the aortic root, the carotid artery, or the cerebral vasculature.

[0011] In another related aspect, a method is provided for treating a patient comprising attaching a conduit to a vessel wall of a blood vessel, the conduit having a lumen extending between a proximal end and a distal end, the distal end of the conduit being attached to the vessel wall, forming an arteriotomy in the vessel wall, inserting a device into the blood vessel through the lumen of the conduit, and performing a treatment with the device.

[0012] In another related aspect, a method is provided for treating a patient having atypical anatomy, the method comprising attaching a conduit to a wall of a blood vessel, the conduit having a lumen extending between a proximal end and a distal end, the distal end of the conduit being attached to the wall of the blood vessel, forming an arteriotomy in the wall of the blood vessel, inserting a device through the lumen of the conduit and into the blood vessel, and performing a treatment with the device.

[0013] In a variation, one or more of the following features may be included in any feasible combination. For example, in some embodiments, the proximal end of the conduit comprises a coupler, and the device is inserted into the lumen of the conduit through the coupler. In some embodiments, attaching the conduit to the vessel wall further comprises suturing the conduit to the vessel wall with a suture. In some embodiments, the method further comprises tightening the suture for primary closure of the vessel after the performing the treatment. In some embodiments, the distal end of the conduit comprises a mechanical element to facilitate attachment of the conduit to the vessel. In some embodiments, the mechanical element comprises a hood, a gasket, or a sewing ring. In some embodiments, forming the arteriotomy comprises forming the arteriotomy through the lumen of the conduit attached to the vessel wall. In some embodiments, the method further comprises reversing blood flow in the vessel during the performing the treatment. In some embodiments, the vessel comprises a common carotid artery. In some embodiments, the blood vessel comprises a vein, a left ventricular apex, an axillary artery, or an aorta. In some embodiments, the method further comprises advancing the device through the common carotid artery to the brachiocephalic artery, the aortic arch, the descending aorta, the ascending aorta, the aortic root, a coronary artery, the internal carotid artery, the external carotid artery, or an intracranial vessel. In some embodiments, the method further comprises advancing the device through the vein, the left ventricular apex, the axillary artery, or the aorta to the brachiocephalic artery, the aortic arch, the descending aorta, the ascending aorta, the aortic root, a coronary artery, the internal carotid artery, the external carotid artery, or an intracranial vessel. In some embodiments, the device comprises a balloon catheter, a stent delivery catheter, or an aspiration catheter. In some embodiments, the device comprises a vascular loop. In some embodiments, the treatment comprises one or more of delivery of a stent, angioplasty dilation, delivery of a stent graft, delivery of a valve, suction embolectomy, and combinations thereof.In some embodiments, the diameter of the lumen of the conduit is about 6 mm or more and about 16 mm or less. In some embodiments, the diameter of the lumen of the conduit is about 8 mm or more and about 10 mm or less. In some embodiments, the conduit further comprises a vascular loop controller located at a proximal end of the conduit opposite the blood vessel, the vascular loop controller configured to actuate one or more vascular loops.

[0014] It should be understood that all combinations of the foregoing concepts and further concepts described in more detail below (provided that such concepts are not mutually inconsistent) are contemplated as part of the inventive subject matter disclosed herein. In particular, all combinations of subject matter recited in the claims of this disclosure are considered to be part of the inventive subject matter disclosed herein. It should also be understood that terms explicitly used in this specification and that may also appear in any disclosures incorporated by reference should be given the meaning most consistent with the particular concepts disclosed herein. [Brief description of the drawings]

[0015] These and other aspects are described in detail with reference to the following drawings: In general, the drawings are not to scale, but are for illustrative purposes, and the relative placement of features and elements may be altered for clarity of illustration.

[0016] [Figure 1A] 1 is a schematic diagram of a retrograde blood flow system including a flow control assembly with an arterial access device accessing the common carotid artery via a transcarotid approach and a venous return device in communication with the internal jugular vein. [Figure 1B] FIG. 1 is a schematic diagram of a retrograde blood flow system with an arterial access device accessing the common carotid artery via a transcarotid approach and a venous return device communicating with the femoral vein. [Figure 1C]FIG. 1 is a schematic diagram of a retrograde blood flow system with an arterial access device accessing the common carotid artery via a transfemoral approach and a venous return device in communication with the femoral vein. [Figure 1D] FIG. 1 is a schematic diagram of a retrograde blood flow system with retrograde blood flow collected in an external reservoir. [Figure 2A] FIG. 1 is an enlarged view of the carotid artery after it has been occluded by an occlusion element on a sheath and connected to a retrograde shunt, and an interventional device, such as a stent delivery system or other working catheter, has been introduced into the carotid artery via an arterial access device. [Figure 2B] 1 shows an alternative system in which the carotid artery is occluded with a separate external occlusion device and connected to a retrograde shunt, and an interventional device, such as a stent delivery system or other working catheter, is introduced into the carotid artery via the arterial access device. [Figure 2C] 1 shows an alternative system in which the carotid artery is connected to a retrograde shunt, an interventional device such as a stent delivery system or other working catheter is introduced into the carotid artery via an arterial access device, and the carotid artery is occluded using a separate occlusion device. [Figure 2D] 1 shows an alternative system in which the carotid artery is occluded and connected to a retrograde shunt via an arterial access device, and an interventional device, such as a stent delivery system, is introduced into the carotid artery via a separate arterial introducer device. [Figure 2E] 1 shows a system in which an arterial access device is inserted through a conduit attached to the common carotid artery. [Diagram 3] A diagram of normal cerebral circulation including the Circle of Willis is shown. [Figure 4] The vasculature of a patient's neck is shown, including the common carotid artery (CCA), internal carotid artery (ICA), external carotid artery (ECA), and internal jugular vein (IJV). [Figure 5A] 1 illustrates one embodiment of an arterial access device useful in the methods and systems of the present disclosure. [Figure 5B] 1 illustrates an embodiment of an arterial access device configuration with a narrowed distal end. [Figure 5C]1 illustrates one embodiment of a conduit for use with a retrograde blood flow system. [Figure 5D] 1 illustrates one embodiment of an arterial access device for use with a conduit. [Figure 5E] 1 illustrates one embodiment of an arterial access device for use with a conduit. [Figure 5F] 1 illustrates one embodiment of a conduit attached to a sheathless arterial access device. [Figure 6] 1 illustrates one embodiment of a sheath inserted into a blood vessel. [Figure 7] 1 shows a sheath positioned within a deep vessel. [Figure 8A] 1 shows a sheath extending through a conduit attached to a blood vessel. [Figure 8B] 1 shows a sheath extending partially through a conduit attached to a blood vessel. [Figure 8C] 1 shows a sheath coupled to a hemostatic valve of a conduit attached to a blood vessel. [Figure 9A] 1 illustrates one embodiment of a venous flow device useful in the methods and systems of the present disclosure. [Figure 9B] 1 illustrates one embodiment of a venous flow device useful in the methods and systems of the present disclosure. [Figure 9C] 1 illustrates one embodiment of a venous flow device useful in the methods and systems of the present disclosure. [Figure 9D] 1 illustrates one embodiment of a venous flow device useful in the methods and systems of the present disclosure. [Figure 10A] 1 illustrates a procedure for implanting a stent at the carotid bifurcation in accordance with the principles of the present disclosure. [Figure 10B] 1 illustrates a procedure for implanting a stent at the carotid bifurcation in accordance with the principles of the present disclosure. [Figure 10C] 1 illustrates a procedure for implanting a stent at the carotid bifurcation in accordance with the principles of the present disclosure. [Figure 10D] 1 illustrates a procedure for implanting a stent at the carotid bifurcation in accordance with the principles of the present disclosure. [Figure 10E] 1 illustrates a procedure for implanting a stent at the carotid bifurcation in accordance with the principles of the present disclosure. [Figure 11] 1 illustrates one embodiment of a large bore delivery system useful in the methods and systems of the present disclosure. [Figure 12A] 12 illustrates the assemblies and components of the system shown in FIG. 11. [Figure 12B] 12 illustrates components of the system shown in FIG. [Figure 12C] 12 illustrates components of the system shown in FIG. [Figure 12D] 12 illustrates components of the system shown in FIG. [Figure 12E] 12 illustrates components of the system shown in FIG. [Figure 13A] 1 illustrates an interconnected embodiment of a large bore delivery system for delivering devices useful in the methods and systems of the present disclosure. [Figure 13B] 1 illustrates an interconnected embodiment of a large bore delivery system for delivering devices useful in the methods and systems of the present disclosure. [Figure 14A] 1 illustrates a conduit with a side port according to an embodiment of the present disclosure. [Figure 14B] 1 illustrates a conduit with a side port according to an embodiment of the present disclosure. [Figure 15A] 1 illustrates a vascular loop assembly according to an embodiment of the present disclosure. [Figure 15B] 1 illustrates a vascular loop assembly according to an embodiment of the present disclosure. [Figure 16] 1 illustrates one embodiment of a coupler consistent with embodiments of the present disclosure. [Figure 17A] 1 illustrates an interconnected embodiment of a conduit assembly for delivering devices useful in the methods and systems of the present disclosure. [Figure 17B] 1 illustrates an interconnected embodiment of a conduit assembly for delivering devices useful in the methods and systems of the present disclosure. [Figure 17C] 1 illustrates an interconnected embodiment of a conduit assembly for delivering devices useful in the methods and systems of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The methods, devices, and systems disclosed herein establish and facilitate vascular access. The methods, devices, and systems may provide temporary vascular access for a variety of indications to limit or prevent emboli release into the cerebral vasculature or into peripheral vasculature leading to the cerebral vasculature, such as the internal carotid artery, including situations of retrograde or reverse blood circulation in the carotid bifurcation region. The methods are particularly useful for interventional procedures, such as, for example, stenting, delivery of stent grafts or valves, and angioplasty, atherectomy, performed through a transcarotid approach to the common carotid artery. The interventional procedures are varied, including access to and treatment of the cerebral vasculature, such as, for example, stroke, intracranial atherosclerosis (ICAD), transient ischemic attack (TIA), acute ischemic stroke (AIS), tandem lesions, embolization of ruptured and unruptured intracranial and extracranial aneurysms, chronic occlusion, and other diseases of the neurovascular system. The present disclosure also relates to methods and systems not directed to the neurovascular system, including treatment of innominate ostial lesions, delivery of stent grafts to the aorta (TEVAR, aortic root valve delivery (TAVR)), and the like. The present disclosure also relates to methods and systems for accessing and treating other vessels by facilitating device delivery and reducing the risk of dissection, especially when the access vessel is particularly deep or the distance before bifurcation is short. The methods, devices, and systems disclosed herein may also be useful for other approaches to the target vessel, including transfemoral, transbrachial, transulnar, transsubclavian, and transradial. The systems disclosed herein may be useful for a variety of indications, including delivery of stents, angioplasty dilation, delivery of stent grafts, delivery of valves, aspiration embolectomy, and combinations thereof, with or without reflux. The systems disclosed herein provide large caliber access with a highly flexible conduit that is temporarily secured to the vascular access site in a manner that allows a variety of angles and curvatures to be achieved without problems of pullout from the access site, kinking or collapse of the lumen.The conduit can have a large inner diameter, and once attached directly to the vessel wall, any of a variety of interventional tools can be inserted through the conduit to perform any of a variety of procedures, after which the conduit can be removed to close the vascular access site. In some embodiments, described in more detail below, an access sheath can be placed through the conduit and the interventional tools can be inserted through the sheath. In other embodiments, no access sheath is used and the interventional tools are inserted through the conduit itself, thereby taking advantage of the improved fluid dynamics of a large caliber conduit attached to a vessel.

[0018] Access to an artery, such as the common carotid artery, may be established by placing a sheath or other tubular access cannula in the lumen of the artery. In the case of the common carotid artery, the distal end of the sheath is typically placed proximal to the junction or bifurcation B of the common carotid artery to the internal and external carotid arteries. In other indications requiring neural access, etc., the sheath may be placed deeper beyond bifurcation B, such as in the intracranial portion of the internal carotid artery (ICA) over the vertebral prominence, and advanced, for example, through the carotid siphon to the distal petrous or cavernous portion of the internal carotid artery, to the cerebral portion of the internal carotid artery, and even to more distal sites such as the anterior and middle cerebral arteries.

[0019] In the case of a retrograde system, the sheath may have an occlusion member at its distal end, e.g., a fitted occlusion balloon. A catheter or guidewire with an occlusion member, such as a balloon, may be placed through the access sheath and placed in the proximal external carotid artery (ECA) to block entry of emboli, although occlusion of the external carotid artery is not usually necessary. A second return sheath may be placed in the venous system, e.g., in the internal jugular vein (IJV) or femoral vein (FV). The arterial access sheath and the venous return sheath may be connected to create an external arterial-venous shunt. The retrograde flow may be established and adjusted to meet the patient's requirements. Blood flow through the common carotid artery may be occluded using either an external vascular loop or tape, a vascular clamp, an internal occlusion member such as a balloon, or other types of occlusion means. When blood flow through the common carotid artery is blocked, the natural pressure gradient between the internal carotid artery and the venous system causes blood to flow retrogradely or in a reverse direction from the cerebral vasculature through the internal carotid artery and the shunt into the venous system. Alternatively, the venous sheath may be omitted and the arterial sheath may be connected to an external collection reservoir or collection container. Retrograde flow may be collected in this collection container. If necessary, the collected blood may be filtered and then returned to the patient during or at the end of the procedure. The pressure in the collection container is released to atmospheric pressure, and a pressure gradient may cause a retrograde flow of blood from the cerebral vasculature to the collection container or the pressure in the collection container may become negative. Optionally, to achieve or enhance retrograde flow from the internal carotid artery, flow from the external carotid artery may be blocked, usually by deploying a balloon or other occlusion element in the external carotid artery just above (i.e., distal to) the bifurcation in the internal carotid artery.

[0020] The conduits described herein can facilitate direct and temporary access to the common carotid artery (CCA) for a sheath and an interventional tool, or for an interventional tool alone without the presence of a sheath. If the vessel at the access site is the common carotid artery (CCA) and the distance between the access site and the bifurcation is very short, no instruments need to be inserted into the vessel. Rather, the conduit may be sewn to the vessel and the instruments may be inserted only into the conduit, thereby reducing the risk of dissecting the vessel at the access site. The conduit sewn to the vessel facilitates direct access to even very deep vessels. Deep vessels tend to increase the risk of dissection because the introducer (introducing instrument) must be inserted into the lumen of the deep vessel or rotated sharply to impinge on the back wall. Sewing the conduit to the deep vessel reduces the risk of dissecting the back wall because the vessel can be accessed by the conduit without the need for abrupt instrument rotation.

[0021] The systems, tools, procedures, and protocols described below may be useful in the treatment of carotid artery disease, such as carotid stenting, angioplasty, atherectomy, and other interventional procedures that may be performed in the carotid system, particularly at locations near the bifurcation of the internal and external carotid arteries. Additionally, the systems and methods may be used in other vascular interventional procedures, such as treating acute strokes in more distal neural structures. The systems and methods described herein may provide conduit access for transcarotid artery revascularization (TCAR) and neurovascular procedures, for example, when the common carotid artery (CCA) is very short or very deep. The systems and methods described herein may provide access ports for procedures other than transcarotid artery revascularization (TCAR) or neurovascular procedures such as aspiration embolectomy. Conduits may be attached to the common carotid artery (CCA) to facilitate delivery of devices directed to the proximal common carotid artery (proximal CCA), the aorta, and other locations. The systems and methods described herein may be used to treat innominate ostial lesions, delivery of stent grafts to the aorta (TEVAR), delivery of valves to the aortic root (TAVR), and other procedures. The left and right carotid arteries may be used as access points, with the right common carotid artery (CCA) accessing the brachiocephalic artery and the left common carotid artery (CCA) directly supplying the aorta, including the aortic arch, ascending aorta, descending aorta, aortic root, coronary arteries, internal carotid artery, external carotid artery, intracranial vessels, etc. Devices used to treat innominate artery disease, aortic disease, or aortic valve disease tend to be very large (e.g., 20F-24F or larger). Delivering these devices through or manipulating within the common carotid artery (CCA) can damage the vessel and cause bleeding in and around the device. Delivering large-caliber devices through a conduit sewn directly into the common carotid artery (CCA) provides a safer and simpler method to access the proximal common carotid artery (proximal CCA), brachiocephalic artery, aorta, and other locations.

[0022] The systems and methods may be part of a retrograde shunt circuit. The retrograde system may be attached directly to the conduit, allowing the larger arterial sheath to be eliminated from the retrograde system. Eliminating the arterial sheath significantly reduces flow resistance throughout the system, thereby increasing retrograde flow and improving embolic protection.

[0023] This application is related to U.S. Patent No. 8,157,760, entitled "METHOD AND SYSTEM FOR ESTABLISHING RETROGRADE CAROTID BLOOD FLOW," and U.S. Patent Application Publication No. 2014 / 0296769, entitled "METHOD AND SYSTEM FOR ESTABLISHING RETROGRADE CAROTID BLOOD FLOW," the contents of both of which are incorporated herein by reference.

[0024] FIG. 1A illustrates a retrograde blood flow system 100 according to a first embodiment. The retrograde blood flow system 100 is configured to establish and promote retrograde or reverse blood circulation in the region of the carotid artery bifurcation to limit or prevent the release of emboli into the cerebral vasculature, particularly the internal carotid artery. The retrograde blood flow system 100 interacts with the carotid artery to provide retrograde blood flow from the carotid artery to a venous return site, such as the internal jugular vein (or in alternative embodiments, another return site, such as another large vein or an external vessel). The retrograde blood flow system 100 includes a conduit 105, an arterial access device 110, a venous return device 115, and a shunt 120 that provides a passage for reverse flow from the arterial access device 110 to the venous return device 115. The arterial access device 110 can be inserted directly into the arterial lumen or via the conduit 105 attached to the arterial wall. A flow control assembly 125 interacts with the shunt 120. The flow control assembly 125 is configured to regulate and / or monitor backflow from the common carotid artery to the internal jugular vein, as described in more detail below. The flow control assembly 125 interacts with the flow path via the shunt 120, either external to the flow path, internal to the flow path, or both. As described in more detail below, the arterial access device 110 is at least partially inserted into the common carotid artery (CCA), and the venous return device 115 is at least partially inserted into a venous return site, such as the internal jugular vein (IJV). In one embodiment, the arterial access device 110 is configured to be insertable through a conduit 105 attached to the common carotid artery such that a distal tip of the arterial access device 110 enters the vessel lumen, or to be only partially insertable through the conduit 105 such that a distal tip of the arterial access device 110 does not directly enter the vessel lumen. In some embodiments, the arterial access device 110 and the conduit 105 are coupled together to place them in fluid communication, but without any portion of the arterial access device 110 inserting substantially within the lumen of the conduit 105. In yet other embodiments, the retrograde blood flow system 100 need not incorporate an arterial access device 110. A conduit 105 attached directly to the blood vessel at the access site can form part of a retrograde shunt circuit.Attaching the retrograde shunt circuit directly to the conduit 105, rather than using a smaller diameter arterial access device 110, improves the fluid dynamics of the retrograde blood flow system and improves embolic protection. Although the retrograde blood flow system is described as having an arterial access device 110 and a conduit 105 that interacts with the arterial access device 110, the retrograde blood flow system may be used without the arterial access device 110 and may instead rely on the conduit 105, as will be described in more detail below.

[0025] The arterial access device 110 and the venous return device 115 couple to the shunt 120 at connection locations 127a, 127b. When blood flow through the common carotid artery is blocked, the natural pressure gradient between the internal carotid artery and the venous system causes blood to flow in a retrograde direction, or retrograde RG (FIG. 2A), from the cerebral vasculature through the internal carotid artery and the shunt 120 into the venous system. The flow control assembly 125 regulates, augments, assists, monitors, and / or otherwise regulates the retrograde blood flow.

[0026] In the embodiment of FIG. 1A, the arterial access device 110 accesses the common carotid artery (CCA) via a transcarotid approach. Transcarotid access provides a short, non-tortuous path from the vascular access point to the target treatment site, which reduces procedure time and difficulty, as compared to, for example, a transfemoral approach. The arterial distance (measured through the artery) from the arteriotomy to the target treatment site is typically 15 cm or less, but may be as short as 5-10 cm. Additionally, this access route reduces the risk of embolic events, as compared to navigating diseased, angulated, or tortuous aortic arch or common carotid tissue when approached from a transfemoral site. At least a portion of the venous return device 115 is positioned in the internal jugular vein (IJV). In one embodiment, transcarotid access to the common carotid artery is achieved percutaneously via an incision or puncture in the skin through which the arterial access device 110 is inserted. If an incision is used, the incision length may be approximately 0.5 cm. An occlusion element 129, such as an expandable balloon, may be used to occlude the common carotid artery (CCA) at a location proximal to the distal end of the arterial access device 110. The occlusion element 129 may be disposed on the arterial access device 110 or may be disposed on a separate device. In an alternative embodiment, the arterial access device 110 accesses the common carotid artery (CCA) via a direct surgical transcarotid approach. In the surgical approach, a tourniquet 2105 may be used to occlude the common carotid artery. The tourniquet 2105 is shown in phantom to indicate that it is a device used in the optional surgical approach. The tourniquet 2105 may be a Rummel device or an arterial loop or other hemostatic technique or tool.

[0027] 1B, an arterial access device 110 accesses the common carotid artery (CCA) via a transcarotid approach, while a venous return device 115 accesses a venous return site other than the jugular vein, such as a venous return site that includes the femoral vein (FV). The venous return device 115 can be inserted into a central vein, such as the femoral vein (FV), via a percutaneous puncture in the groin.

[0028] In another embodiment shown in Figure 1C, the arterial access device 110 accesses the common carotid artery via a femoral approach. According to the femoral approach, the arterial access device 110 approaches the common carotid artery (CCA) via a percutaneous puncture into the femoral artery (FA), such as in the groin, and travels up the aortic arch (AA) to the target common carotid artery (CCA). The venous return device 115 can communicate with the jugular vein (JV) or the femoral vein (FV).

[0029] FIG. 1D illustrates yet another embodiment, in which the retrograde blood flow system 100 provides for backflow from the carotid artery to an external container 130 rather than to a venous return site. The arterial access device 110 is connected to the external container 130 via a shunt 120 in communication with a flow control assembly 125. The backflow of blood is collected in the external container 130. If desired, the blood can be filtered and then returned to the patient. The pressure in the external container 130 may be set to zero pressure (atmospheric pressure) or even lower, allowing blood to flow in a retrograde direction from the cerebral vasculature to the external container 130. Optionally, to achieve or enhance backflow from the internal carotid artery, flow from the external carotid artery can be blocked, usually by placing a balloon or other occlusion element in the external carotid artery just above its bifurcation with the internal carotid artery. Although FIG. 1D illustrates the arterial access device 110 placed in a transcarotid approach via the common carotid artery (CCA), it should be understood that the use of the external container 130 may also be used for the arterial access device 110 in a transfemoral approach.

[0030] Referring to the close-up view of the carotid artery in FIG. 2A, an interventional device, such as a stent delivery system 135 or other working catheter, may be introduced into the carotid artery via the arterial access device 110, as described in detail below. The stent delivery system 135 may be used to treat plaque P, such as by deploying a stent within the carotid artery. The arrow RG in FIG. 2A represents the direction of retrograde blood flow. Alternatively, the conduit 105 may be attached directly to the common carotid artery (CCA) and the stent delivery system 135 may be inserted directly through the conduit 105 without the arterial access device 110. The conduit 105 may be part of a retrograde shunt circuit that provides improved embolic protection due to its larger inner diameter. The conduit 105 may be sized to accommodate devices that are 4-6° F., 10-15° F., 20-24° F., or higher temperatures up to about 28° F., and any temperature in between. Devices used for transcarotid revascularization may be delivered through the conduit 105 (e.g., stent delivery systems, balloons) and tend to be in the size range of 4-6°F. The conduit 105 can also allow passage of devices in the range of 10-15°F, so long as it maintains retrograde flow. In some embodiments where the device is introduced in a retrograde direction (e.g., towards the brachiocephalic artery or aorta), the device introduced through the conduit 105 can be in the size range of 24-36°F.

[0031] Figure 2B illustrates another embodiment, in which an arterial access device 110 is used to create an arterial-venous shunt and to introduce at least one interventional device into the carotid artery. A separate arterial occlusion device 112 with an occlusion element 129 may be used to occlude the common carotid artery (CCA) proximal to the distal end of the arterial access device 110 (see Figure 2C).

[0032] 2D illustrates yet another embodiment in which an arterial access device 110 is used to create an arterial-venous shunt and an arterial occlusion using an occlusion element 129. A separate arterial introducer device may be used to introduce at least one interventional device into the carotid artery distal to the arterial access device 110.

[0033] FIG. 2E illustrates a retrograde blood flow system 100 according to another embodiment. In this embodiment, an arterial access device 110 is inserted through a conduit 105 attached to the common carotid artery and has a coupler 107, such as a female luer fitting, a one-way, two-way, or multi-way rotating hemostatic valve (RHV), or other adapter or coupling. The coupler 107 may be any of a variety of adapters for a vascular graft that allow sealing and access to the lumen of the conduit 105. Further embodiments of the coupler 107 and conduit 105 are illustrated in FIGS. 11-17C. The distal end of the conduit 105 may be temporarily attached to the vessel wall. The proximal end of the conduit 105 may extend outside the body to allow a user to access the lumen of the conduit 105 through the coupler 107 to insert an interventional device (e.g., a catheter such as a balloon catheter, a large bore aspiration catheter, a stent delivery catheter, etc.). The arterial access device 110 can extend through the conduit 105 such that the distal end of the arterial access device 110 is inserted into the artery (see FIG. 5E and FIG. 8A). The arterial access device 110 can extend partially through the conduit 105 such that the distal end of the arterial access device 110 does not directly enter the artery (see FIG. 8B). Yet another embodiment is contemplated in which the arterial access device 110 does not insert into the conduit 105 at all, but instead simply couples with a coupler 107 to place the conduit 105 and the arterial access device 110 in fluid communication with each other (see FIG. 5F). Although FIG. 2E shows the conduit 105 attached to the common carotid artery, the conduit 105 can be attached to another access site, including a radial, ulnar, subclavian, brachial, or femoral access site. The conduit 105 may be used in combination with a retrograde blood flow system, such that the larger inner diameter of the conduit 105 may provide advantages from a hydrodynamic standpoint for improving aspiration and / or retrograde flow. As discussed above, the conduit 105 may be attached directly to the common carotid artery (CCA) and form part of a retrograde shunt circuit without the use of an arterial access device 110. Interventional devices may be inserted into the vessel through the conduit 105 without having to traverse a smaller diameter access sheath.The interventional device can have significantly smaller dimensions than the conduit 105 such that retrograde flow through the circuit is improved compared to when the interventional device is inserted through an 8F arterial sheath. The larger diameter conduit 105 also allows for the insertion of larger devices that would be difficult to advance through a conventional sheath system. The neuroprotection system can be attached directly to the conduit 105 without the need for an arterial sheath, which can significantly reduce flow resistance throughout the system, improving embolic protection from retrograde flow. This is a major advantage when delivering balloon or stent systems, as a large portion of the cross-sectional area of ​​the sheath is blocked when placed within the arterial sheath. The risk of developing an embolus is increased during some procedures, such as transcarotid artery revascularization (TCAR) procedures, where catheters and instruments are delivered within the vasculature. Improving the retrograde flow rate during these "high risk" stages of the procedure can improve the overall outcome of the procedure. Reducing blood flow resistance may also reduce or eliminate the need to increase the patient's systemic blood pressure during a transcarotid artery revascularization (TCAR) procedure. Typically, a transcarotid artery revascularization (TCAR) procedure may involve increasing the patient's blood pressure to a hypertensive state (e.g., 140-160 mmHg) during the high-risk phase of the procedure. Elevated blood pressure increases the arteriovenous pressure difference, thereby increasing backflow within the system and theoretically improving embolic protection. With low resistance within the large-caliber conduit 105, good embolic protection can be achieved without the need to increase the patient's blood pressure from the inside, thereby simplifying the procedure and benefiting the patient.

[0034] Each of the above embodiments, and others, are described in greater detail below.

[0035] <Explanation of anatomical structure (biological structure)> [Collateral cerebral circulation] The Circle of Willis (CW) is the major arterial anastomosis trunk of the brain, connecting all the major arteries supplying blood to the brain, namely the two internal carotid arteries (ICA) and the vertebrobasilar system. Blood is carried from the Circle of Willis to the brain by the anterior, middle, and posterior cerebral arteries. This communication between arteries allows collateral circulation through the brain. It allows blood to flow through alternative routes, thereby providing a safety mechanism in the event that one or more of the blood vessels supplying the brain are occluded. The brain can continue to receive an adequate blood supply in most cases, even if there is an occlusion anywhere in the arterial system (e.g., when the internal carotid artery (ICA) is ligated as described herein). Blood flow through the Circle of Willis ensures adequate cerebral blood flow by multiple pathways that redistribute blood to the deprived side.

[0036] The collateral potential of the Circle of Willis is thought to depend on the presence and size of its constituent vessels. It should be understood that there may be considerable anatomical variation among individuals in these vessels, and many of the involved vessels may be diseased. For example, some individuals may lack one of the communicating arteries. If an occlusion occurs in such an individual, collateral circulation may be compromised, ischemic phenomena may occur, and brain damage may result. Additionally, the autoregulatory response to a drop in perfusion pressure may include enlargement of collateral arteries, such as the communicating arteries of the Circle of Willis. This compensatory mechanism may require time for adjustment before collateral circulation reaches a level that will support normal function. This autoregulatory response may occur over 15-30 seconds and is only compensable within a certain pressure range and within a certain range of flow reduction. Thus, transient ischemic attacks may occur during the adjustment period. Extremely high retrograde flow rates over a prolonged period may result in a condition in which the patient's brain does not receive sufficient blood flow, which may lead to patient intolerance as indicated by neurological symptoms and possibly transient ischemic attacks.

[0037] Figure 3 shows normal cerebral circulation and the formation of the Circle of Willis (CW). The aorta (AO) gives rise to the brachiocephalic artery (BCA), which branches into the left common carotid artery (LCCA) and the left subclavian artery (LSCA). The aorta (AO) further gives rise to the right common carotid artery (RCCA) and the right subclavian artery (RSCA). The vertebral artery (VA) branches from the left subclavian artery (LSCA) and the right subclavian artery (RSCA). The left and right common carotid arteries (CCA) give rise to the internal carotid arteries (ICA), which branch into the middle cerebral artery (MCA), posterior communicating artery (PCoA), and anterior cerebral artery (ACA). The anterior cerebral artery (ACA) supplies blood to parts of the frontal lobe and the striatum. The middle cerebral artery (MCA) is a large artery with tree-like branches that carry blood throughout the sides of each hemisphere of the brain. The right and left posterior cerebral arteries (PCAs) arise from the basilar artery (BA) and carry blood to the back of the brain (occipital lobes).

[0038] Anteriorly, the circle of Willis is formed by the anterior cerebral artery (ACA) and the anterior communicating artery (ACoA), which connects the two anterior cerebral arteries (ACA). Two posterior communicating arteries (PCoA) connect the circle of Willis to the two posterior cerebral arteries (PCA) and branch off the basilar artery (BA) to complete the communicating arteries posteriorly.

[0039] The common carotid artery (CCA) also gives rise to the external carotid artery (ECA), which branches extensively to supply most structures of the head except the brain and orbital contents. The ECA also helps supply structures of the neck and face.

[0040] [Carotid artery bifurcation] Figure 4 shows a close-up of the relevant vasculature in the patient's neck. The common carotid artery (CCA) bifurcates at bifurcation B into the internal carotid artery (ICA) and the external carotid artery (ECA). Bifurcation B is located at approximately the level of the fourth cervical vertebra. Figure 4 shows plaque P formed at bifurcation B.

[0041] As mentioned above, the common carotid artery (CCA) can be accessed via a transcarotid approach. According to the transcarotid approach, the common carotid artery (CCA) can be accessed at an arterial access location L. The access can be, for example, a surgical incision or a puncture in the wall of the common carotid artery (CCA). Typically, there is a distance D of about 5-7 cm between the arterial access location L and the bifurcation B. When the arterial access device 110 is inserted into the common carotid artery (CCA), it is undesirable for the distal tip of the arterial access device 110 to contact the bifurcation B, as this may disrupt plaque P and cause the generation of embolic particles. This is especially dangerous when the common carotid artery (CCA) is short. To minimize the possibility of the arterial access device 110 contacting the bifurcation B, in one embodiment, only about 2-4 cm of the distal region of the arterial access device may be inserted into the common carotid artery (CCA) during the procedure.

[0042] In other embodiments, the arterial access device 110 is placed in fluid communication with the common carotid artery via a conduit 105 attached to a vessel wall, such as the anterior vessel wall (see FIG. 2E and FIGS. 8A-8C). The distal tip of the arterial access device 110 is inserted a short distance into the vessel lumen through the lumen of the conduit 105 (FIG. 8A) or does not enter the vessel lumen at all and remains within the lumen of the conduit 105 (FIG. 8B). The conduit 105 can provide a safer insertion of the arterial access device 110 and reduce the risk of plaque rupture. The conduit 105 can also reduce the risk of injury to the artery, for example, from vessel dissection or vessel perforation.

[0043] In yet another embodiment, the conduit 105 is attached directly to the common carotid artery (CCA) and the system completely eliminates the arterial access device 110. Interventional tools are inserted directly through the conduit 105 which forms part of the retrograde shunt circuit. Although a configuration has been described in which the arterial access device 110 is inserted through the conduit 105, it should be understood that an interventional device or tool may be inserted through the conduit without incorporating the arterial access device 110 into the system.

[0044] The common carotid artery is surrounded on both sides by a layer of fascia called the carotid sheath. The carotid sheath also encases the internal jugular vein and the vagus nerve. In front of the carotid sheath is the sternocleidomastoid muscle. Percutaneous or surgical transcarotid access to the common carotid artery and internal jugular vein can be achieved through the carotid sheath just above the clavicle, between the two crests of the sternocleidomastoid muscle, taking care to avoid the vagus nerve. One complication during insertion of the arterial access device 110 is dissection of the common carotid artery (CCA), especially in anatomy where the CCA is located relatively deep beneath the surface of the skin S. When the common carotid artery (CCA) is located deep beneath the skin and sternocleidomastoid muscle, the insertion angle can be greater than 50 degrees, for example up to about 80 degrees. This angle can result in dissection of the vessel wall during insertion, or even perforation of the posterior wall of the artery.

[0045] The conduit 105 can facilitate safe insertion of catheters (e.g., interventional tools, arterial access device 110, etc.) into the common carotid artery (CCA) even in challenging anatomy that causes steep entry angles. The conduit 105 can be a temporary vascular conduit attached to the anterior wall of the common carotid artery (CCA) via sutures using standard surgical techniques. "Temporary" as used herein refers to a period of time sufficient to perform an interventional procedure. The conduit 105 that is attached to the blood vessel and provides temporary access for the procedure is temporary in that flow from the blood vessel through the conduit 105 is occluded after the procedure because the conduit 105 is detached from the blood vessel and the opening of the blood vessel is closed or the lumen of the conduit 105 is occluded or sealed, preventing flow through the conduit 105 after the procedure. The arterial access device 110 can be inserted through the conduit lumen rather than directly into the blood vessel wall and does not need to be advanced to the blood vessel lumen to be in fluid communication with the blood vessel lumen. The conduit 105 reduces the risk of common carotid artery (CCA) dissection or the inadvertent release of embolic material from plaque at the carotid bifurcation.

[0046] Devices inserted through conduit 105 may be advanced proximally from the common carotid artery into, for example, the brachiocephalic artery, the aortic arch, portions of the aorta including the descending or ascending aorta, the aortic root, or a coronary artery. Conduit 105 may also provide access for devices intended for insertion into the internal carotid artery, external carotid artery, or intracranial vessels for neurovascular procedures.

[0047] [Detailed description of the retrograde blood flow system with additional conduits] As described above, the retrograde blood flow system 100 according to one embodiment includes an arterial access device 110, a venous return device 115, a shunt 120 that provides a pathway for retrograde blood flow from the arterial access device 110 to the venous return device 115, and a conduit 105. The conduit 105 is configured to attach to an arterial wall and fluidly connect the arterial access device 110 to an arterial lumen (see FIG. 5D). The retrograde blood flow system 100 also includes a flow control assembly 125 that interacts with the shunt 120 to regulate and / or monitor retrograde blood flow through the shunt 120. The arterial access device 110 can directly access a blood vessel or can be accessed via a separate conduit 105. In an embodiment, the retrograde blood flow system 100 can incorporate a conduit 105 having a distal end configured to attach directly to a blood vessel wall and a proximal end configured to couple to the shunt 120 via a coupler 107 or the like. This embodiment does not incorporate an arterial access device 110. Exemplary embodiments of the components of the retrograde blood flow system 100 will now be described.

[0048] [conduit] FIG. 5C illustrates a conduit 105 according to one embodiment. The conduit 105 may be configured for use with the retrograde blood flow system 100. The conduit 105 may be a flexible tubular structure that can be attached to a vessel wall. The material of the conduit is flexible and radially expandable. This allows larger devices to be delivered through the conduit 105 while minimizing the size of the arteriotomy / anastomosis. The conduit 105 may be coated on the inside and / or outside with anti-thrombogenic materials (e.g., heparin) and / or hydrophilic materials to facilitate delivery of instruments and devices through the lumen of the conduit 105. The conduit 105 may be configured to accommodate patient anatomy and / or pathology that is not conducive to large bore access, for example, short / deep vessel procedures, patients with disease, dissections, patients with scar tissue, etc. The conduit 105 may also reduce the difficulties and risks associated with such procedures and patients. 11-17C show other interrelated embodiments of conduits, which are described in more detail below.

[0049] The conduit body may be a knitted or woven fabric that may provide flexibility and may be coated with a polymer to provide resistance to blood leakage through the fabric. For example, the knitted or woven fabric may be polyethylene terephthalate (PET) and the coating may be polyurethane or a similar polymer. The coating to prevent leakage may be concentrated at the location where the suture passes. The coating may also reduce fraying of the fabric at the distal and / or proximal ends. The fabric may be a polyethylene terephthalate (Dacron) fabric impregnated with collagen to create a leak-free conduit (e.g., Hemashield Gold graft from Maquet, Getinge AB).

[0050] The conduit 105 may be a synthetic arterial prosthesis or a molded biotextile. The conduit 105 may be an arterial vascular graft manufactured from a substrate and extruded into a tubular shape. The substrate may be a synthetic polymeric material such as polyethylene terephthalate (Dacron), polyester, nylon, expanded polytetrafluoroethylene (ePTFE), heparin-bonded ePTFE, hooded PTFE, ring-reinforced ePTFE, nylon-ePTFE hybrid fabric, or other suitable material. The conduit 105 may be formed of a commercially available vascular graft, such as CARBOFLOW (Bard), FLIXENE PTFE (Atrium Medical), PROPATEN (Gore), a bilayer heparin vascular graft with ePTFE and PET layers (FUSION BIOLINE, Getinge AB), HERO hemodialysis access graft (Merit Medical), and ACUSEAL (Gore). The conduit 105 may be formed of a bioabsorbable material, such as, for example, polyglycolic acid (PGA), polyglycolic acid-polylactic acid (PGA-PLA), glycolic / lactic acid polymer (PGLA), polycaprolactone (PCL), and the like.

[0051] The distal end of the conduit 105 may be attached to the vessel wall according to techniques known in the art. In some embodiments, the conduit 105 is sutured to the vessel wall such that the lumen of the conduit 105 is placed in fluid communication with the vessel lumen. The conduit 105 can be sutured to the vessel wall using standard surgical techniques to form an end-to-side anastomosis (see Criado "Iliac arterial conduits for endovascular access: technical considerations" J. Endovasc. Ther. 2007 14(3):347-351). The conduit 105 may also be attached using a sutureless technique to form an end-to-side anastomosis. The conduit 105 may be implanted in the artery such that it is disposed at an angle relative to the longitudinal axis of the vessel lumen. The angle between the conduit 105 and the longitudinal axis of the vessel lumen can vary within a range of 0 degrees to 90 degrees, preferably within a range of 20 degrees to 45 degrees. The flexibility of the conduit 105 compared to conventional access sheaths, combined with the flexibility of the blood vessel, allows for relatively extreme attachment angles while still allowing safe passage of the device through the conduit 105 and into the blood vessel.

[0052] The conduit 105 may be sewn directly to the vessel prior to creating the arteriotomy that will form the anastomosis. Once the anastomosis is complete, the arteriotomy may be created from inside the conduit. In this manner, no distal or proximal prerequisites are required prior to the anastomosis. The sutures used to sew the conduit 105 to the vessel to create the anastomosis may also be used for primary closure of the arteriotomy in the vessel at the conclusion of the procedure after the conduit 105 has been removed from its attachment.

[0053] The distal end region of the conduit 105 may include mechanical features configured to reduce bleeding and promote faster anastomosis. The mechanical features may include a hood, gasket, sewing ring, or similar features disposed at the distal end region of the conduit 105. The distal end region of the conduit 105 may include a pre-placed or pre-sewn closure suture, such that at the end of the procedure performed through the conduit 105, the pre-placed suture may be tightened to quickly close the conduit 105 and the vessel, similar to a "suture" technique. Pre-positioning the suture to be sutured to the distal end region of the conduit 105 may help ensure more accurate placement of the closure suture to more completely and more efficiently close the conduit 105. With suture techniques, small remnants of conduit material may remain after closure, but the remnants do not carry blood.

[0054] The conduit 105 may incorporate a reinforcing feature in the proximal end region. The reinforcing feature on the conduit may include one or more coils, braids, rings, or combinations thereof configured to reduce kinking or crushing when the conduit 105 is bent. The reinforcing feature may extend from the proximal end region to a location 1-2 cm proximal to the most distal end of the conduit 105. That is, the distal 1-2 cm of the conduit 105 may be unreinforced to maintain the conformability and flexibility of the conduit material. This non-reinforced region may be sewn to the vessel.

[0055] The conduit 105 has an inner diameter sufficient to accommodate the outer diameter of an arterial access device or the outer diameter of various interventional devices and tools used in procedures, including transcarotid artery revascularization (TCAR), treatment of innominate artery ostial lesions, delivery of stent grafts to the aorta (TEVAR), delivery of valves to the aortic root (TAVR), neurovascular procedures, and the like. In some embodiments, the conduit 105 may have an inner diameter of about 6 mm to about 16 mm. In some embodiments, the conduit 105 may have an inner diameter of about 6 mm to about 15 mm. In some embodiments, the conduit 105 may have an inner diameter of about 7 mm to about 12 mm. In some embodiments, the conduit 105 may have an inner diameter of about 8 mm to about 10 mm. In some embodiments, the sheath of the arterial access device 110 is sized in the range of 7 Fr to 10 Fr. In this case, the inner diameter of the conduit 105 is sized to accommodate a sheath in that size range. Typically, the outer diameter of an 8 Fr sheath is about 10.5 F (1 Fr = 0.33 mm). A sheath of this size is large enough to be inserted through the arterial wall into the vessel lumen without unnecessary damage to the artery and to allow strong backflow for embolic protection. The conduit 105 can be significantly larger than this size because it is attached to the vessel wall rather than inserted through the vessel wall, which typically has an inner diameter of about 6 mm. The outer diameter of the sheath entering the vessel is limited by the inner diameter of the vessel lumen, but the outer diameter of the conduit 105 is not. The outer diameter of the conduit 105 may be about 16 Fr or more and about 20 Fr or less, and may have an inner diameter in the range of 15 Fr or more and 18 Fr or less (5-6 mm). Devices used to treat innominate artery disease, aortic disease, or aortic valve disease may be sized within the range of 20 Fr or more and 24 Fr or more. The conduit 105 may be sized to accommodate sizes up to 24 Fr or more for these procedures. In some embodiments, the sheath size of the arterial access device 110 is in the range of 12 Fr to 36 Fr inclusive. In some embodiments, the sheath size of the arterial access device 110 is in the range of 14 Fr to 20 Fr inclusive.

[0056] The conduit 105 may have any reasonable inner diameter that allows for implantation into the vessel wall and adequate fluid flow through the conduit 105 for embolic protection during the procedure. In some embodiments, the inner diameter of the conduit is between about 2 mm and about 10 mm, or between about 4 mm and about 8 mm. The arterial lumen may be about 6-8 mm depending on the size of the conduit. In some embodiments, the inner diameter of the conduit approaches the inner diameter of the blood vessel to which the conduit is attached. It should be understood that the arterial access device 110 does not need to be inserted into the lumen of the conduit 105 to be placed in fluid communication with the blood vessel. For example, since the arterial access device 110 does not have a distal sheath, upon coupling the arterial access device to the coupler 107, blood flows directly from the common carotid artery (CCA) to the inner diameter of the conduit 105, and the system is effectively free of an arterial sheath. This reduces the resistance to fluid flow that would occur if blood flowed into a smaller arterial sheath (e.g., 2,7 mm inner diameter). Reducing the resistance to fluid flow increases backflow through the system. The inner diameters of other components in the system may also be increased to further reduce flow resistance from the point where blood proximally enters the conduit.

[0057] The conduit 105 may have a length between the proximal and distal openings of the conduit 105 during use. The length of the conduit 105 may be between about 1 cm and 15 cm, preferably between about 5 cm and 10 cm, and in some applications up to about 20 cm and 30 cm. A length greater than 20 cm may be considered, for example, to connect directly to a blood vessel while keeping the user away from the x-ray beam during fluoroscopy. The length of the conduit 105 is sufficient to attach to the anterior wall of the common carotid artery (CCA), even if the CCA is a deep anatomical structure. The length of the conduit 105 is also sufficient to allow the length to extend outside the neck incision to couple with the arterial access device 110 without creating external tension on the system. The length of the conduit 105 may be customized during use. Thus, the length of the conduit 105 may be manufactured to be longer than the length that may be used during a procedure, for example, at least about 30 cm, or between about 20 cm and about 50 cm. Also, the length of the conduit 105 may be trimmed (cut) to a size for use, for example, from about 5 cm to about 30 cm. In yet other embodiments, the conduit 105 may be provided in a variety of pre-sized lengths ranging from about 5 cm up to about 30 cm. The length of the conduit 105 between the proximal and distal ends may be longer than the length of the distal sheath, such that as the distal sheath extends through the lumen of the conduit 105, the distal end of the distal sheath remains inside the lumen of the conduit proximal to the distal end of the conduit. For example, the conduit may have an insertable length of about 5 cm to about 30 cm, and the insertable length of the distal sheath may be shorter, for example, from about 4 cm to about 29 cm.

[0058] An apparatus such as an arterial access device 110 (arterial sheath) or another device may be inserted through a proximal opening in the conduit 105 or through a sidewall of the conduit 105. The arterial access device 110 (arterial sheath) or another device may be secured within the conduit 105 using a Rummel tourniquet, a vascular loop, or a similar device. Regardless of how the arterial access device 110 (arterial sheath) (or a retrograde shunt if no arterial sheath is incorporated) is placed in fluid communication with the conduit 105, leakage of blood around the sheath and inadvertent movement of the sheath relative to the conduit should be controlled.

[0059] In one embodiment, the conduit 105 may have a coupler 107 disposed within a proximal opening of the conduit 105. The coupler 107 may be a luer fitting, a hemostasis valve adapter (HVA), a rotating hemostasis valve (RHV), or other type of connection device. The coupler 107 may be configured to attach to a standard connector (e.g., a syringe, a stopcock, a hemostasis valve, a Y connector, or other type of connector). The coupler 107 may provide both securement of a sheath, such as an arterial access device 110 or a shunt, providing proximal attachment to the conduit 105, and hemostasis against blood leakage during use. Further interrelated embodiments of the coupler 107 are described in Figures 11, 12A, 12E-14A, and 16, as well as elsewhere herein. The coupler 107 may be an integrated non-standard connector that limits compatibility to certain mating components. The coupler 107 may be a multi-port adapter with a rotating hemostasis valve on each port. The multi-port adapter allows for the introduction of additional devices into the conduit 105 (and optionally the common carotid artery (CCA)). For example, one or more ports can be used for the delivery of a "buddy" wire or support catheter to facilitate delivery of an interventional device (e.g., 0.014 inch guidewire, balloon catheter, stent delivery system) to a target location. One or more ports can be used to attach an auxiliary extracorporeal shunt line to increase retrograde flow through the retrograde blood flow system 100. One or more ports can be used to deliver an aspiration catheter into a vessel, for example, into the common carotid artery (CCA) or further into the internal carotid artery (ICA) to provide auxiliary embolic protection during a procedure or to provide aspiration to remove a thrombus in the case of an acute ischemic stroke. The conduit 105 can be incorporated into a retrograde flow system that can be used with any of a variety of tools for any of a variety of procedures in the neurovasculature, coronary arteries, and peripheral vessels. The inner diameter of the conduit 105 and the stable connection between the conduit 105 and the blood vessel at the access site allows additional flexibility in the procedure that can be performed while still providing adequate embolic protection.Blood flow through the aspiration catheter may be passive, or blood flow may be supplemented by an external vacuum pump.

[0060] A distal portion of the arterial access device 110 (e.g., distal sheath 605 shown in FIG. 5A) may, but need not, be inserted through the conduit 105. In some embodiments, the distal sheath 605 is inserted at least partially through the coupler 107 into the lumen of the conduit 105 (see FIG. 5E and FIGS. 8A-8B). The distal sheath 605 inserted into the lumen of the conduit 105 may be inserted deep enough that a coupler (e.g., distal connector 690 shown in FIG. 5D) on the arterial access device 110 proximal to the distal sheath 605 may engage and attach to the coupler 107 of the conduit 105. The distal sheath 605 further includes a sheath lumen, which may have a diameter of about 12 Fr or more and about 36 Fr or less. In some embodiments, the diameter of the sheath lumen may have a diameter of about 14 Fr or more and about 20 Fr or less. In other embodiments, the coupler 107 of the conduit 105 may be attached directly to the coupler of the arterial access device 110 without inserting the distal sheath 605 into the lumen of the conduit 105 (see FIG. 5F). The conduit 105 attached to the arterial wall may take the place of any arterial sheath that is normally inserted into the vessel lumen. As discussed elsewhere herein, eliminating the presence of the sheath body in the retrograde flow circuit significantly reduces flow resistance, increases retrograde flow rate, and improves embolic protection. The conduit 105 is temporary and is removed after use, for example, by removing the sutures and closing the hole in the vessel.

[0061] [Arterial access device] FIG. 5A illustrates an exemplary embodiment of an arterial access device 110 that may include a distal sheath 605, a proximal extension 610, a flow path 615, an adapter or Y-connector 620, and a hemostasis valve 625. The arterial access device may also include a dilator 645 with a tapered distal end 650 and an introducer guidewire 611. The arterial access device may be used with the dilator and introducer guidewire to access a vessel. The functionality of the arterial access device may be optimized for transcarotid access. For example, the design of the access device components may be optimized to limit potential vessel damage from sharp insertion angles, allow for atraumatic and secure sheath insertion, and limit the length of the sheath, sheath dilator, and introducer guidewire inserted into the vessel.

[0062] In some embodiments, the distal sheath 605 includes an occlusion element 129 for occluding flow through a blood vessel, for example, the common carotid artery. If the occlusion element 129 is an inflatable structure, such as a balloon, the distal sheath 605 can include an inflation lumen in communication with the occlusion element 129. The occlusion element 129 can be an inflatable balloon, but can also be an inflatable cuff, a cone-shaped or other circumferential element that expands outwardly to engage the inner wall of the common carotid artery to block antegrade flow past the occlusion element 129, a membrane-covered braid, a slotted tube that expands radially when compressed axially, or a similar structure that can be deployed by mechanical means. In the case of balloon occlusion, the balloon can be compliant, non-compliant, elastomeric, reinforced, or have a variety of other properties. In one embodiment, the balloon is an elastomeric balloon that is received snugly on the outside of the distal end of the sheath before inflation. Upon inflation, the elastomeric balloon expands to conform (fit) the inner wall of the blood vessel. In one embodiment, the elastomeric balloon can expand to a diameter at least twice that of the undeployed configuration, and often can expand to a diameter at least three times that of the undeployed configuration, and more preferably at least four times or more that of the undeployed configuration.

[0063] FIG. 2B illustrates an alternative embodiment, in which the occlusion element 129 may be introduced into the blood vessel on a second sheath (arterial occlusion device 112) separate from the distal sheath 605 of the arterial access device 110. The second or "proximal" sheath (arterial occlusion device 112) may be configured to be inserted into the blood vessel toward the proximal or "downward" direction, away from the cerebral vasculature. The second or proximal sheath (arterial occlusion device 112) may include an inflatable balloon (occlusion element 129) or other occlusion element, generally as described above. The distal sheath 605 of the arterial access device 110 may then be positioned within the blood vessel distal to the second or proximal sheath and generally oriented distally toward the cerebral vasculature. The use of separate occlusion and access sheaths may reduce the size of the arteriotomy required for introduction of the access sheath.

[0064] 2C illustrates yet another embodiment of a dual arterial sheath system in which an interventional device is introduced through an introducer sheath 114 that is separate from the distal sheath 605 of the arterial access device 110. The second or "distal" sheath 114 may be configured for insertion into the vessel distal to the arterial access device 110. As with the previous embodiment, the use of two separate access sheaths may reduce the size of each arteriotomy.

[0065] When the sheath is inserted at an acute angle, such as in a transcarotid access procedure to the common carotid artery, and / or when the length of the sheath inserted into the artery is short, the distal end of the sheath is likely to partially or completely impinge on the vessel wall, thereby restricting flow into the sheath. In one embodiment, the sheath is configured to center its tip in the vessel lumen. One such embodiment includes a balloon, such as the occlusion element 129 described above. In another embodiment, the balloon does not occlude flow, such as an inflatable bumper, but can still center the tip of the sheath away from the vessel wall. In another embodiment, an expandable feature is located at the tip of the sheath and is mechanically expanded once the sheath is in place. Examples of mechanically expandable features include braided structures, helical structures, or longitudinal struts that radially expand when foreshortened.

[0066] The distal sheath 605 is configured to be introduced through an incision, arteriotomy, or puncture in the vessel wall, e.g., a surgical incision or percutaneous puncture established using the Seldinger technique. The length of the distal sheath 605 may range from 5 cm to 15 cm, and typically is 10 cm to 12 cm. The distal sheath 605 may also be disposed in fluid communication with the vessel via the conduit 105, as discussed elsewhere herein. In yet another embodiment, the arterial access device 110 does not have a distal sheath 605, which will be described in more detail below.

[0067] The inner diameter of the distal sheath 605 may range from 7 Fr (1 Fr=0.33 mm) to 10 Fr, typically 8 Fr. If the distal sheath 605 is inserted through an arteriotomy, the outer diameter is preferably in the range of about 10 Fr or less. As described in more detail below, the distal sheath 605 may be of a larger diameter, for example in the range of 15 Fr to about 18 Fr, for use with the conduit 105.

[0068] It is desirable for the distal sheath 605 to be highly flexible while maintaining hoop strength to resist kinking and buckling, especially when the sheath is introduced into the common carotid artery supraclavicular and below the carotid bifurcation via a transcarotid approach. Thus, the distal sheath 605 may be circumferentially reinforced by braid, helical ribbon, helical wire, cut tube, etc., and has an inner liner such that the reinforcement structure is sandwiched between the outer jacket layer and the inner liner. The inner liner may be a low friction material such as PTFE. The outer jacket layer may be one or more of a group of materials including polyether block amide copolymer (Pebax), thermoplastic polyurethane, or nylon. In one embodiment, the reinforcement structure or material, and / or the material or thickness of the outer jacket layer may vary with longitudinal position of the distal sheath 605, thereby allowing for varying flexibility along the length.

[0069] The conduits described herein may be attached to any of a variety of access points including the carotid, femoral, radial, brachial, ulnar, or subclavian arteries. Certain vascular structures such as veins, the left ventricular apex, the axillary artery, the aorta, etc. may be used for alternative large diameter access, such as access using a large diameter delivery system 1100 as described in further detail elsewhere herein. These structures are not as robust as the carotid artery, and procedures on these structures may benefit from attachment of a conduit 105, which may be made of inorganic or graft materials, such as those of the large diameter delivery system described herein (see Figures 11-17C). The conduits may be attached to the walls of these access vessels and to another access device, such as a distal sheath 605, which is advanced through the access vessel. Preferably, the conduits provide access without the insertion of other access devices or sheaths into the conduits, allowing interventional devices to be inserted directly through the conduits into the anatomical structure to be treated. The interventional device may include a balloon catheter, a stent delivery catheter, an aspiration catheter, and the like. The interventional device may be inserted under retrograde flow using a retrograde system attached directly to a coupler on the conduit 105. The target vessel may also vary, including extracranial or intracranial vessels. The target vessel may include the common carotid artery (CCA), external carotid artery (ECA), internal carotid artery (ICA), cerebral artery (M1 or M2 portion of the middle cerebral artery), vertebral artery, subclavian artery, brachiocephalic artery, brachiocephalic artery, ascending aorta, aortic arch, descending aorta, or aortic root. Other target vessels include vessels of the coronary anatomy, peripheral anatomy, or other vasculature. The coronary arteries include the left and right coronary arteries, the posterior descending artery, the right marginal artery, the left anterior descending artery, the left circumflex artery, the M1 left marginal artery, and the M2 left marginal artery, as well as the D1 diagonal branch and the D1 diagonal branch. Any of a variety of peripheral blood vessels are considered target vessels herein, including the popliteal artery, anterior tibial artery, dorsalis pedis artery, posterior tibial artery, and peroneal artery. Where specific anatomical structures are mentioned in connection with the devices described herein, other anatomical structures are contemplated, although they may not be specific in each case.

[0070] In some embodiments, as shown in FIG. 5B, the distal sheath 605 may have a stepped or other configuration with a distal region 630 that has a smaller outer diameter compared to the more proximal regions. FIG. 5B shows a close-up of the distal region 630 of the distal sheath 605. The distal region 630 of the sheath may be sized for insertion into the carotid artery and typically has an inner diameter in the range of 0.085 inches to 0.115 inches. The remaining proximal region of the sheath has a larger outer and lumen diameter, with the inner diameter typically in the range of 0.110 inches to 0.135 inches. The larger lumen diameter of the proximal region minimizes the overall flow resistance of the sheath. In one embodiment, the reduced diameter distal region (distal section) 630 has a length of about 2 cm to 4 cm. The relatively short length of the narrowed distal region (distal section) 630 allows this section to be placed in the common carotid artery (CCA) via a transcarotid approach while reducing the risk of the distal end of the distal sheath 605 contacting bifurcation B. Additionally, the narrowed distal region (distal section) 630 also allows for a reduced size of the arteriotomy for introducing the distal sheath 605 into the artery while minimizing the effect on the level of blood flow resistance. Additionally, the narrowed distal region (distal section) 630 may be more flexible, which may allow it to better fit the lumen of the blood vessel.

[0071] 5A, the proximal extension 610, which is an elongate body, has a lumen that is continuous with the lumen of the distal sheath 605. The lumen may be joined by a Y-connector 620 that connects the lumen of the flow path 615 to the sheath. The flow path connection may terminate in a valve, and the sheath may include a Y-adapter that connects a distal portion of the sheath to the proximal extension 610. The Y-adapter may include a valve that may be operated to open or close a fluid connection to a connector or hub that is removably connectable to a flow path, such as a shunt. The valve may be located immediately adjacent to the lumen of the adapter that communicates with the lumen of the distal sheath 605.

[0072] In the assembled system, the flow path 615 connects to the retrograde shunt 120, forming the first shunt limb of the shunt 120 (see FIG. 1A). The proximal extension 610 may be long enough to space the hemostatic valve 625 far enough away from the Y-connector 620 adjacent to the percutaneous or surgical insertion site. By spacing the hemostatic valve 625 away from the percutaneous insertion site, a physician may introduce tools such as a stent delivery system or other working catheter into the proximal extension 610 and distal sheath 605 while remaining out of the fluoroscopic field of view when a fluoroscopic examination is being performed. In one embodiment, the proximal extension 610 is approximately 16.9 cm from its most distal junction with the distal sheath 605 (e.g., the hemostatic valve 625) to the proximal end of the proximal extension 610. In one embodiment, the proximal extension has an inner diameter of 0.125 inches and an outer diameter of 0.175 inches. In one embodiment, the wall thickness of the proximal extension is 0.025 inches. The inner diameter may be, for example, in the range of 0.60 inches to 0.150 inches, and the wall thickness may be, for example, in the range of 0.010 inches to 0.050 inches. In another embodiment, the inner diameter may be, for example, in the range of 0.150 inches to 0.250 inches, and the wall thickness may be, for example, in the range of 0.025 inches to 0.100 inches. The dimensions of the proximal extension may vary. In one embodiment, the proximal extension has a length in the range of about 12 cm to 20 cm. In another embodiment, the proximal extension has a length in the range of about 20 cm to 30 cm.

[0073] In one embodiment, the distance along the sheath from the hemostatic valve 625 to the distal end of the distal sheath 605 is in the range of about 25 cm to 40 cm. In one embodiment, the distance is in the range of about 30 cm to 35 cm. With a system configuration that allows for 2.5 cm sheath introduction into the artery and an arterial distance of 5-10 cm from the arteriotomy site to the target site, the system allows for a distance from the hemostatic valve 625 (location of introduction of the interventional device into the access sheath) to the target site of 32-43 cm, in the range of about 32.5 cm to 42.5 cm. This distance is approximately one-third the distance required by the prior art.

[0074] In system configurations where a sheath is not introduced into the artery and the conduit 105 is attached to the arterial wall, the sheath dimensions may be the same or different as described above. Similarly, the sheath dimensions may be optimized to have optimized dimensions depending on the access site (e.g., femoral, radial, brachial, ulnar, subclavian, carotid, etc.) and indication (e.g., carotid stenting under reflux) used. In some embodiments, the length of the conduit 105 from the proximal opening to the distal opening may be about 5 cm or more and about 30 cm or less. The coupler 107 may add additional length to bring the total length to about 6 cm or more and about 31 cm or less. The distal sheath 605 may be shorter than this length, such as about 5 cm or more and about 30 cm or less, such that the distal tip of the distal sheath 605 remains within the conduit 105 during use. In other embodiments, the distal sheath 605 is longer than this length such that at least a portion of the distal sheath 605 extends within the arterial lumen. The length of the distal sheath 605 extending into the arterial lumen can be from about 1 cm to about 5 cm. This can depend on the patient's anatomy and the length of the conduit 105. In general, if the vessel is about 4-5 cm deep or deeper, direct insertion of the arterial sheath into the vessel faces greater difficulties and challenges. Factors such as the length of the vessel, the presence or absence of disease in the vessel near the desired insertion point, the consistency of the vessel wall, the operator's technique, and the presence of disease distal to the insertion point can all affect direct insertion of the sheath into the vessel. The conduit 105 can be used to mitigate challenges caused by any of these factors. In some embodiments, the distal sheath 605 can be inserted about 2.5 cm into the vessel to ensure adequate stability. During insertion of the distal sheath 605, the tip of the dilator can extend (e.g., about 1.5 cm) beyond the tip of the distal sheath 605. To provide adequate support for the distal sheath 605 and dilator during insertion, a guidewire (e.g., a 0.035 inch guidewire) is also inserted a minimum distance into the vessel beyond the arteriotomy, which may be approximately 5 cm, but is preferably longer than this.A system incorporating conduit 105 can access blood vessels and establish retrograde flow within a patient without placing instruments, including distal sheaths, dilators, or guidewires, distal to the arteriotomy.

[0075] The conduit 105 may be a pre-cut conduit. A pre-cut conduit provides optimal access angles for large bore devices and eliminates the need for the physician to modify the conduit 105 during the procedure. The conduit 105 may be pre-cut to a desired length, such as from about 5 cm to about 30 cm in length, as described above. Improved attachment of the conduit 105 to the patient's blood vessel may improve the seal of the conduit 105 to the access site and allow for use of the conduit 105 in other medical specialties that are less familiar with attaching conduits. In some embodiments, the conduit 105 may be formed from a bioabsorbable material that facilitates re-access by leaving no material at the access site, and a radiopaque marker that allows visualization of previous access sites. In some embodiments, the conduit 105 may be attached directly to the artery or vascular structure via sutures or other suitable attachment methods (e.g., clips, staples, etc.). In some embodiments, the conduit 105 may have a 15-25 degree angle at the distal end 1125 of the conduit 105, which may aid in attachment of the conduit 105 and a direct access angle for auxiliary devices, including sheaths and delivery systems. In some embodiments, the conduit 105 may have a pre-attached absorbable material, for example, configured as a pledget or suture cuff for attachment to the artery, or a bioabsorbable material (e.g., PGA, PGA-PLA, etc.). In some embodiments, the outer body of the conduit 105 may be configured to be straight, wavy, or have an outer ring for kink resistance. In some embodiments, the conduit 105 may have radiopaque markers embedded therein to aid in visualization for re-access. Radiopaque markers may include any substance capable of absorbing x-rays, such as barium or iodine. A radiopaque marker may be embedded into the material of the conduit 105, imprinted on the surface of the conduit 105, glued to the surface of the conduit, or otherwise placed on or within the conduit 105 to aid in visualization of the access site for potential re-access.

[0076] 5A-5B, the flush line 635 can be connected to the side of the hemostasis valve 625 and can have a stopcock 640 at its proximal or distal end. The flush line 635 allows for the introduction of saline, contrast, etc. during the procedure. The flush line 635 can also allow for pressure monitoring during the procedure. A dilator 645 having a tapered distal end 650 can be provided to facilitate the introduction of the distal sheath 605 into the common carotid artery. The dilator 645 can be introduced through the hemostasis valve 625 such that the tapered distal end 650 extends through the distal end of the distal sheath 605. The dilator 645 can have a central lumen to accommodate the guidewire 611. Typically, the guidewire 611 is placed in the vessel first, and the dilator / sheath combination travels over the guidewire 611 as it is introduced into the vessel. When used with the conduit 105, the guidewire 611 is not necessary. Rather, the distal sheath 605 with the dilator 645 may be inserted through the coupler 107 of the conduit 105 attached to the blood vessel.

[0077] The distal sheath 605 may be configured to establish a curved transition from a generally anterior-posterior approach on a vessel, such as the common carotid artery, to a generally axial luminal direction within the vessel. Arterial access through a vessel wall by direct surgical incision or percutaneous access may require access at a different angle that is greater than other arterial access sites, especially if the insertion site is much closer to the treatment site (i.e., the carotid bifurcation) than other access points. For example, arterial access through the common carotid artery (CCA) wall may require a larger access angle compared to access through the femoral vessel wall in the groin. For common carotid artery (CCA) access and carotid treatment sites, a larger access angle is required to increase the distance from the insertion site to the treatment site so that the sheath can be inserted at an appropriate distance without the distal tip of the sheath reaching the carotid bifurcation. For example, the insertion angle of the sheath is typically 30-45 degrees, or even greater, for transcarotid access, whereas for femoral artery access, the insertion angle of the sheath may be 15-20 degrees. The sheath may be configured to bend more than is typical for introducer sheaths without kinking or causing excessive forces on the opposing arterial wall. Additionally, it is desirable for the sheath tip not to abut or contact the arterial wall after insertion in a manner that would restrict flow into the sheath. The sheath insertion angle is defined as the angle between the luminal axis of the artery and the longitudinal axis of the sheath.

[0078] The distal sheath 605 may be shaped in a variety of ways to allow for this greater flexure necessitated by the access angle. For example, the sheath and / or dilator may have a combined flexible bending stiffness that is lower than that of a typical introducer sheath. In one embodiment, the sheath / dilator combination (i.e., a sheath with a dilator placed inside the sheath) has a combined bending stiffness of approximately 80-100 N·m 2 ×10 -6 The sheath has a combined bending stiffness (EI) in the range of 30 to 40 N m, where E is the elastic modulus and I is the cross-sectional moment of inertia of the device. The bending stiffness of the sheath alone is approximately 30 to 40 N m 2 ×10 -6 The bending stiffness of the expander alone is in the range of 40 to 60 N·m2 ×10 -6 The bending stiffness of a typical sheath / dilator is in the range of 150 to 250 N·m. 2 ×10 -6 The stiffener material and design may provide greater flexibility. For example, the sheath may have a stainless steel ribbon coil stiffener with dimensions of 0.002" to 0.003" thick, 0.005" to 0.015" wide, and an outer jacket durometer of 40-55D. In one embodiment, the coil ribbon is 0.003" by 0.010" and the outer jacket durometer is 45D. In one embodiment, the distal sheath 605 may be preformed to have a curve or angle at a predetermined distance from the tip, typically 0.5-1 cm. The preformed curve or angle may provide a rotational range of typically 5 degrees to 90 degrees, preferably 10 degrees to 30 degrees. For initial introduction, the distal sheath 605 may be straightened with an obturator or other straightening instrument or shaped instrument such as a dilator 645 placed within its lumen. After the distal sheath 605 has been introduced at least partially through a percutaneous or other arterial wall penetration, the obturator is withdrawn, allowing the distal sheath 605 to resume its preformed shape within the arterial lumen. To retain the curved or angled shape of the sheath body after being straightened during insertion, the sheath may be heat set into the angled or curved shape during manufacture. Alternatively, the reinforcing structure may be constructed from Nitinol and heat formed into the curved or angled shape during manufacture. Alternatively, additional spring elements may be added to the sheath body, for example, strips of correctly shaped spring steel or Nitinol may be added to the reinforcing layer of the sheath.

[0079] Other sheath configurations include having a deflection mechanism such that the sheath can be positioned and the catheter can be deflected in situ to a desired deployment angle. In yet other configurations, the catheter has a non-rigid configuration when positioned within the lumen of the common carotid artery. Once in place, pull wires or other stiffening mechanisms can be deployed to mold and stiffen the sheath to a desired shape. One particular example of such a mechanism is commonly known as a "shape lock" mechanism, as is well described in the medical and patent literature.

[0080] Another sheath configuration involves a curved dilator inserted into a straight but flexible sheath, with the dilator and sheath curving during insertion, the sheath being flexible enough to conform to the anatomy after removal of the dilator.

[0081] Another sheath embodiment is a sheath that includes one or more flexible distal sections, such that once inserted and in an angled configuration, the sheath can bend at large angles without kinking or causing excessive forces on the opposing arterial wall. In one embodiment, there is a distal-most section of the sheath body that is more flexible than the remainder of the sheath body (distal sheath 605). For example, the bending stiffness of the distal-most section is 2-10 times less than the bending stiffness of the remainder of the sheath body (distal sheath 605). In one embodiment, the distal-most section has a bending stiffness of 30-300 N·m 2 , and the remainder of the sheath body (distal sheath 605) has a bending stiffness in the range of 500 to 1500 N·m 2For a sheath configured for a common carotid artery (CCA) access site, the flexible distal-most section comprises a significant portion of the sheath body (distal sheath 605) that can be expressed as a ratio. In one embodiment, the ratio of the length of the flexible distal-most section to the total length of the sheath body (distal sheath 605) is at least one-tenth and at most one-half the length of the entire sheath body (distal sheath 605). This change in flexibility can be achieved in a variety of ways. For example, the outer jacket may vary in durometer and / or material in various portions. Alternatively, the reinforcing structure or material may vary over the length of the sheath body. In one embodiment, the distal-most flexible section ranges from 1 cm to 3 cm. In an embodiment having two or more flexible sections, the less flexible section (relative to the distal-most section) may be 1 cm to 2 cm from the distal-most proximal section. In one embodiment, the distal flexible section has a stiffness of about 30 to 50 N·m. 2 ×10 -6 The less flexible sections have a bending stiffness in the range of about 50-100 N·m 2 ×10 -6In another embodiment, the more flexible sections are placed between 0.5-1.5 cm with lengths between 1-2 cm to form an articulation section that allows the distal section of the sheath to more easily align with the vessel axis, even if the sheath enters the artery at an angle. These configurations with variable flexibility sections can be manufactured in several ways. For example, the reinforced less flexible section may vary such that there is a stiffer reinforcement in the proximal section and a softer reinforcement in the distal or articulation section. In one embodiment, the outermost jacket material of the sheath has a durometer of 45D-70D in the proximal section and a durometer of 80A-25D in the most distal section. In one embodiment, the flexibility of the sheath varies continuously along the length of the sheath body. The flexible distal section of the sheath body (distal sheath 605) allows the sheath to bend and the distal tip to be approximately aligned with the vessel lumen. In one embodiment, the distal section is made with a softer reinforcement structure by changing the pitch of the coil or braid, or by incorporating cut hypotubes with a different cut pattern, or the distal section has a different reinforcement structure than the proximal section.

[0082] In one embodiment, the distal sheath tapered tip is manufactured from a harder material than the distal sheath body. The purpose of this is to facilitate insertion of the sheath by allowing a very smooth taper of the sheath and reducing distortion and ovalization changes of the sheath tip during and after insertion of the sheath into the vessel. In one example, the distal tapered tip material is manufactured from a higher durometer material, for example, 60D-72D Shore material. In another example, the distal tip is manufactured from a separate material, for example, HDPE, stainless steel, or other suitable polymer or metal. In an additional embodiment, the distal tip is manufactured from a radiopaque material, either as an additive to the polymeric material, for example, tungsten or barium sulfate, or as an inherent property of the material (as is the case with most metallic materials).

[0083] When used with a conduit 105, the sheath need not have such an angle since the sheath can remain within the lumen of the conduit rather than being inserted directly into the vessel lumen distal to the arteriotomy.

[0084] In another embodiment, the introducer guidewire 611 is optimally configured for transcarotid access. Typically, when inserting the introducer sheath into a blood vessel, the introducer guidewire is inserted into the blood vessel first. This can be done using either the micropuncture technique or the modified Seldinger technique. Typically, there is a long blood vessel in the direction of the sheath insertion, into which the introducer guidewire can be inserted, for example, into the femoral artery. In this case, the user can introduce the guidewire 10 cm to 15 cm or more into the blood vessel before inserting the sheath. The guidewire is configured to have a flexible tip portion so as not to injure the blood vessel when it is introduced into the artery. The flexible section of the introducer sheath guidewire 611 is typically 5-6 cm in length and gradually transitions into a stiffer section. Inserting the guidewire 10-15 cm places the stiffer portion of the guidewire in the puncture area, allowing it to stably support the subsequent insertion of the sheath and dilator into the blood vessel. However, when inserting a transcarotid sheath into the common carotid artery, there is a limit to the amount of guidewire that can be inserted into the carotid artery. If there is carotid disease at the bifurcation or internal carotid artery, it is desirable to minimize the risk of emboli by inserting the wire into the external carotid artery (ECA), which means only 5-7 cm of guidewire insertion, and preferably the wire stops before reaching the bifurcation (only 3-5 cm of guidewire insertion). Thus, a transcarotid sheath guidewire may have a distal flexible section of 3-4 cm, and / or a shorter transition to a stiffer section. Alternatively, a transcarotid sheath guidewire may have an atraumatic tip section, but a shorter transition to a stiffer section very distally. For example, the soft tip section may be 1.5-2.5 cm, followed by a transition section 3-5 cm long, followed by a stiffer proximal section, with the stiffer proximal section making up the remainder of the wire.

[0085] To use this embodiment of the sheath system, a micropuncture kit may be used to initially access the vessel. First, a 0.018 inch guidewire is inserted into the vessel through the 22 Ga needle. The coaxially assembled sheath system is then inserted over the 0.018 inch wire. First, an inner tube is advanced over the 0.018 inch wire, essentially converting it into a wire equivalent to a 0.035 inch or 0.038 inch guidewire in both outer diameter and mechanical support. The inner tube is secured to the 0.018 inch wire at the proximal end. The sheath and dilator are then advanced into the vessel over the 0.018 inch wire and inner tube. This configuration eliminates the need for a long taper on the dilator as with current transradial sheaths, and uses the same guidewire support as a standard introducer sheath, eliminating the need for a wire exchange step. As mentioned above, this configuration of the sheath system can include a stop mechanism that prevents the 0.018 inch guidewire and / or inner tube from inadvertently advancing too far during insertion of the sheath. Once the sheath is inserted, the dilator, inner tube, and 0.018 inch guidewire are removed.

[0086] The operator can also drill a larger hole in the arterial wall and attach the conduit 105 to provide a larger access area through which the sheath can be delivered, or the flow reversal system can be attached directly without a sheath.

[0087] Another arterial access device is shown in Figures 5D-5E. This configuration has a different style of connection to the retrograde shunt than the version previously described with respect to Figures 5A-5B. Figure 5D shows the components of the arterial access device 110, including the arterial access sheath (distal sheath 605), sheath dilator (dilator 645), conduit 105, and sheath guidewire 611. Figure 5E shows the arterial access device 110 assembled over the sheath guidewire 611 for insertion into a vessel, which may be the common carotid artery or another access site described elsewhere herein. After the sheath is inserted into fluid communication with the artery, such as via the conduit 105, the sheath guidewire 611 and sheath dilator (dilator 645) are removed (if used). In this configuration, the sheath has a sheath body (distal sheath 605), a proximal extension 610, and a proximal hemostatic valve 625 with a flush line 635 and a stopcock 640. The proximal extension 610 extends from the Y adapter 660 to a hemostasis valve 625 to which a flush line 635 is connected. The sheath body (distal sheath 605) is formed to a size that allows it to be inserted into the carotid artery, and is the portion that is actually inserted into the artery during use.

[0088] Instead of a Y-connector with a fluid path connection terminating in a valve, the sheath has a Y-adapter 660 that connects the distal portion of the sheath to the proximal extension 610. The Y-adapter can also include a valve 670 that can be operated to open or close a fluid connection to a connector or hub 680 that can be removably connected to a fluid path such as a shunt. The valve 670 is located immediately adjacent to the lumen of the Y-adapter 660 that communicates with the lumen of the sheath body (distal sheath 605). The valve 670 is closed to the connector during preparation of the arterial sheath. The valve 670 is configured to eliminate the possibility of air being trapped during preparation of the sheath. The valve 670 opens to the connector once the shunt 120 is connected to the hub 680, allowing blood flow from the arterial sheath to the shunt. This configuration eliminates the need to prepare both a flush line and a flow line, instead allowing preparation from a single flush line 635 and stopcock 640. This single point preparation is the same as preparation of a conventional introducer sheath that does not have a connection to a shunt line, and is therefore more familiar and convenient for the user. Additionally, the lack of movement in the sheath allows for easier handling of the arterial sheath during preparation and insertion into the artery.

[0089] 5D, the sheath may also include a more distal second connector (distal connector 690) that is separated from the Y-adapter 660 by a segment of tubing 665. The purpose of this second connector and tubing 665 is to allow the valve 670 to be positioned further proximally from the distal end of the sheath while still limiting the length of the insertable portion of the distal sheath 605, thus reducing the user's level of exposure to the radiation source when the flow shunt is connected to the arterial sheath during the procedure. In one embodiment, the distal connector 690 includes a suture eyelet that helps secure the positioned sheath to the patient.

[0090] As an exemplary method, the conduit 105 may be useful during a transcarotid artery revascularization (TCAR) procedure. In this procedure, an arterial sheath (distal sheath 605) may be inserted directly into the patient's common carotid artery (CCA) or through the conduit 105. It should be understood that the arterial sheath (distal sheath 605) need not be inserted through the conduit 105, as long as it can also be inserted into the common carotid artery. As described elsewhere herein, to achieve retrograde blood flow, the common carotid artery (CCA) may be occluded to stop antegrade blood flow from the aorta through the common carotid artery (CCA). Flow through the common carotid artery (CCA) may be occluded with an external vascular loop or internal occlusion member such as a tape, vascular clamp, balloon, or other type of occlusion means such as a tourniquet 2105 as shown in FIG. 1A. When flow through the common carotid artery (CCA) is blocked, the natural pressure gradient between the internal carotid artery (ICA) and the venous system causes blood to flow in a retrograde or reverse direction from the cerebral vasculature. Blood from the internal carotid artery (ICA) and external carotid artery (ECA) flows in a retrograde direction, and the system described herein allows the retrograde blood to flow through the flow control assembly 125, the venous return device 115, into the arterial sheath (distal sheath 605), and then back into the patient's femoral vein, as described elsewhere herein. Loose embolic material may be carried into the arterial sheath (distal sheath 605) with the retrograde blood flow.

[0091] Manual occlusion of the vessel V by the clinician at an occlusion location proximal to the distal tip of the arterial sheath (distal sheath 605) may be provided from outside the vessel V using a vascular clamp 800, such as a Rummel tourniquet or vessel loop, positioned proximal to the sheath insertion site. An occlusion device may be attached to the outside of the vessel V around the sheath tip, such as an elastic loop, an inflatable cuff, or a mechanical clamp that can be tightened around the vessel and distal sheath tip. In a flow reversal system, this type of vessel occlusion may minimize the creation of static blood flow zones, thereby reducing the risk of thrombus formation. This ensures that the tip of the sheath is axially aligned with the vessel V, avoiding partial or complete occlusion of the distal opening by the vessel wall.

[0092] FIG. 6 shows an arterial sheath (distal sheath 605) inserted directly into a vessel V, such as the common carotid artery or another vascular access site exposed through an incision I. The vascular access site does not need to be an ablation procedure, it can be a percutaneous procedure. A sheath guidewire 611 and an arterial access sheath dilator (dilator 645) protrude from a distal opening near a distal region of the arterial sheath (distal sheath 605). As described in U.S. Patent Application Publication No. 2019 / 0125512, a sheath stopper 705 can be used with the arterial sheath (distal sheath 605) to prevent overinsertion of the arterial sheath (distal sheath 605) through the arteriotomy. FIG. 7 shows the arterial sheath (distal sheath 605) extending distal to the sheath stopper 705 inside the vessel V. The conduit 105 can be used to insert the arterial sheath (distal sheath 605) into a vessel without a sheath stopper 705 or mechanical hard stop that establishes the insertion length of the arterial sheath (distal sheath 605), for example, when deeper access of the arterial sheath (distal sheath 605) is desired. The arterial sheath (distal sheath 605) can be advanced through the common carotid artery distal to the bifurcation into the distal portion of the internal carotid artery or through the petrous portion of the internal carotid artery (ICA). In this embodiment, it may be preferable to omit the sheath stopper 705 to provide deeper access that is not limited by a mechanical stop. Other indications may benefit from the presence of a sheath stopper, for example, when it is preferred that the sheath be implanted proximal to the bifurcation.

[0093] The sheath stopper 705 may be in the form of a tube that is coaxially received on the outside of the distal sheath 605. The sheath stopper 705 is configured to prevent the sheath from being inserted too deeply into the vessel V. The sheath stopper 705 is sized and shaped to be disposed on the sheath body (distal sheath 605) so as to cover a portion of the sheath body (distal sheath 605) and leave a distal portion of the sheath body (distal sheath 605) exposed. The sheath stopper 705 may have a flared proximal end that engages with the adapter (Y connector 620) and a distal end that abuts the exterior of the vessel V. The length of the sheath stopper 705 limits the introduction of the distal sheath 605 to the exposed distal portion of the distal sheath 605 such that the sheath insertion length is limited to the exposed distal portion of the sheath. In one embodiment, the sheath stopper limits the exposed distal portion to a range between 2 cm to 3 cm. In one embodiment, the sheath stopper limited the exposed distal portion to 2.5 cm. In other words, the sheath stopper can limit the insertion of the sheath into the artery to a range between about 2 cm to 3 cm, or to 2.5 cm. Second, the sheath stopper 705 engages with a pre-deployed puncture closure device (if present) positioned in the carotid artery wall, allowing the distal sheath 605 to be withdrawn without removing the closure device. The sheath stopper 705 may also be made from a flexible material, or the sheath stopper 705 includes articulations or portions of increased flexibility so that the sheath can bend as needed in place once inserted into the artery. The sheath stopper may be plastically bendable so that it can be bent into a desired shape such that it retains that shape when released by the user. The distal portion of the sheath stopper may be made from a harder material and the proximal portion from a softer material. In one embodiment, the harder material is 85A durometer and the softer portion is 50A durometer. In one embodiment, the stiffer distal portion is 1-4 cm of the sheath stopper 705.The sheath stopper 705 may be removable from the sheath, so that if a user desires a longer sheath insertion, the user can remove the sheath stopper 705, cut it shorter (the length of the sheath stopper), and reassemble the sheath stopper 705 onto the sheath so that a longer insertable sheath length protrudes from the sheath stopper 705.

[0094] The sheath stopper 705 can be deformed from a first shape, such as a straight shape, to a second shape different from the first shape, and the sheath stopper retains the second shape until a sufficient external force acts on the sheath stopper to change shape. The second shape can be, for example, a non-straight, curved, or other contoured or irregular shape. The sheath stopper 705 can have multiple bends as well as straight sections. The sheath stopper 705 has a higher stiffness than the distal sheath 605 such that the distal sheath 605 assumes a shape or contour that matches the shape of the contour of the sheath stopper 705.

[0095] The sheath stop 705 can be shaped according to the angle of sheath insertion into the artery and the depth of the artery or the patient's anatomy. This feature reduces the force of the tip of the sheath on the vessel wall, especially when the sheath is inserted into the vessel at a steep angle. The sheath stop can be bent or otherwise deformed into a shape that helps orient the sheath coaxially with the entering artery, even when the angle of entry into the arteriotomy is relatively steep. The sheath stop can be shaped by the operator prior to inserting the sheath into the patient. Alternatively, the sheath stop can be shaped and / or reshaped in situ after the sheath is inserted into the artery.

[0096] In one embodiment, the sheath stopper 705 is made from a malleable material or made of an integral malleable component disposed on or within the sheath stopper. In another embodiment, the sheath stopper is constructed to articulate using an actuator such as a concentric tube, pull wire, or the like. The walls of the sheath stopper may be reinforced with ductile wire or ribbon to help the sheath stopper retain its shape against external forces such as when it encounters a bend in the artery or inlet. Alternatively, the sheath stopper may be constructed of a homogenous malleable tubular material including metals and polymers. The sheath stopper body may be constructed at least in part of a reinforced braid or coil that can retain its shape after deformation.

[0097] Another sheath stop embodiment is configured to facilitate adjustment of the position of the sheath stop (relative to the sheath) even after the sheath is positioned within the vessel. One sheath stop embodiment includes a tube with slits along most or all of its length so that the sheath stop can be peeled away from the sheath body, moved forward or backward as desired, and then repositioned along the length of the sheath body. The tube includes a tab or mechanism at the proximal end so that it can be grasped and more easily peeled away.

[0098] In another embodiment, the sheath stop is a very short tube (such as a band) or ring on the distal section of the sheath body. The sheath stop may include features that allow it to be easily grasped, for example with forceps, and pulled back and forth to a new position as desired to set the appropriate sheath insertion length for the procedure. The sheath stop may be secured to the sheath body by friction from the tubing material or by a clamp that can be opened and closed relative to the sheath body. The clamp may be a spring-loaded clamp that is normally clamped to the sheath body. To move the sheath stop, the user opens the clamp with a finger or an instrument, adjusts the clamp position, and then releases the clamp. The clamp is configured to not interfere with the sheath body.

[0099] In another embodiment, the sheath stop includes a feature that allows the sheath stop and sheath to be sutured to the patient's tissue to improve fixation of the sheath and reduce the risk of sheath dislodgement. This feature may be a suture eyelet attached to or molded into the sheath stopper tube.

[0100] In another embodiment, as shown in FIG. 6, the sheath stopper 705 includes a distal flange sized and shaped to distribute the force of the sheath stopper over a larger area of ​​the vessel wall, thereby reducing the risk of vessel injury or accidental insertion of the sheath stopper into the vessel through an arteriotomy. The flange may have a round or other atraumatic shape large enough to distribute the force of the sheath stopper over a larger area on the vessel wall. In one embodiment, the flange is inflatable or mechanically expandable. For example, the arterial sheath and sheath stopper may be inserted into the surgical area through a small puncture in the skin and then expanded prior to inserting the sheath into the artery.

[0101] The sheath stopper may include one or more notches or indentations patterned in a staggered configuration along the length of the sheath stopper, such that the indentations increase the flexibility of the sheath stopper while maintaining axial strength to allow forward force of the sheath stopper against the arterial wall. The indentations may also be used to facilitate securing the sheath to the patient via sutures to mitigate sheath dislodgement. The sheath stopper may also include a connector element at the proximal end that corresponds to features of the arterial sheath so that the sheath stopper can be locked or unlocked to the arterial sheath. For example, the connector element may be a hub with a generally L-shaped slot that corresponds to a pin on the hub, creating a bayonet mount style connection. In this way, the sheath stopper may be securely attached to the hub, reducing the likelihood that the sheath stopper will be inadvertently removed from the hub unless unlocked from the hub.

[0102] FIG. 7 shows the distal end of the arterial sheath (distal sheath 605) extending through sheath stop 705 into vessel V along a very steep entry angle. The angle between the axis of vessel V and the axis of the arterial sheath (distal sheath 605) (proximal to the bend) is shown to be approximately 50-60 degrees, however, depending on the patient anatomy, this angle may be closer to 90 degrees from the axis of vessel V. The distal-most tip of the arterial sheath (distal sheath 605) extends toward the posterior wall of vessel V which, along with the steep angle, increases the risk of arterial dissection and perforation.

[0103] The conduit 105 can have a distal-most end configured to be secured to the wall of the blood vessel by sutures that create a leak-tight connection with the blood vessel, unlike the sheath stopper 705. The flexible conduit 105 can effectively become an extension of the blood vessel itself, like a temporary anastomosis into which an arterial sheath (distal sheath 605) can be inserted.

[0104] The conduit 105 material, as described elsewhere herein, is inert, biocompatible, and strong. The conduit 105 material can be conformable, customizable, and relatively easy to work with. The conduit 105 material can be attached to the vessel wall by suturing, as opposed to other types of conduits 105 that can only be inserted through holes in the vessel sidewall. In some embodiments, the conduit 105 can be formed of a polymer, such as polyethylene terephthalate (Dacron), polyfluorotetraethylene (PTFE), or a bioabsorbable material (e.g., PGA, PGA-PLA, PLGA, PCL, etc.). The conduit 105 can be formed of one or more layers of material, such as expanded PTFE (ePTFE). A soft, pliable material, such as ePTFE, that can carry liquids, such as blood, while minimizing leakage through the wall, is preferred. The flexibility and malleability of the material used to form the conduit 105 allows needles and sutures to pass through the wall, making the conduit 105 relatively easy to suture. The material is also preferably tear resistant, making it easier to sew than, for example, silicone rubber tubing. The conduit 105 is preferably formed of a compliant material that is tear resistant, relatively impermeable to fluids, and thrombus resistant, so that the conduit 105 can carry blood through its lumen and also form a leak-tight seal at the conduit-vessel interface. ePTFE possesses all of these properties and is particularly well suited for forming the conduit 105. Other materials, such as tightly woven Dacron, may have similar properties. A flexible elastomeric material, such as silicone, may be used if additional structural reinforcement is incorporated into the conduit to prevent tearing. However, reinforced silicone elastomers provide a more cost-effective alternative than ePTFE, given the short-term nature of the temporarily attached conduit 105.

[0105] The layers of the conduit 105 may be formed into a substantially cylindrical or tubular shape according to known techniques (e.g., extrusion, dip coating a mandrel, etc.). The tubular shape may be tapered such that a first end of the conduit 105 is smaller than an opposing end of the conduit 105. The inner diameter of the conduit 105 may be constant from the proximal to the distal end or may increase in the proximal direction near the coupler.

[0106] The conduit 105 may be configured to suture to the vessel wall. The material of the tubular conduit 105 is configured to be penetrated by needles and sutures without catching, peeling, or tearing the walls of the conduit 105 and while maintaining a substantial seal. The wall thickness of the conduit 105 may be from about 0.25 mm to about 3.0 mm. In some embodiments, the conduit 105 has a graduated wall thickness such that the wall thickness of at least one region is reduced for suturing. The segment of reduced wall thickness of the conduit 105 may be at least 1 mm long from the distal-most end. The sealing of the sutured region allows the conduit 105 to be used to pass fluids in and out of the vessel lumen as well as to insert devices therein.

[0107] In some embodiments, the conduit 105 may include an inner layer, a middle layer, and an outer layer of material. The inner layer may be heparinized to prevent platelet adhesion, and the middle layer may be elastomeric and configured to minimize post-suturing oozing and suture hole bleeding.

[0108] The exterior surface of the conduit 105 may have one or more visual markers to identify the length of the conduit 105 from the proximal coupler. The visual markers may provide a guide for a user wishing to customize the length of the conduit 105 prior to use. For example, the conduit 105 may be provided with a length of at least about 20 cm from the coupler to the most distal end. The conduit 105 may have visual markers every 5 cm from the coupler to the most distal end so that a 20 cm long conduit 105 can be more easily changed to a length of 15 cm, 10 cm, or 5 cm. The visual markers may provide various graduations to identify the length.

[0109] 8A-8C show a distal sheath 605 extending through the coupler 107 of the conduit 105 with its distal end attached to the wall of the blood vessel V. The distal sheath 605 may be inserted through the coupler 107 on the proximal end of the conduit 105. FIG. 8A shows that the distal end of the distal sheath 605 extends completely through the conduit 105 and out the distal end, such that the distal end of the distal sheath 605 may be disposed inside the blood vessel V. FIG. 8B shows that the distal end of the distal sheath 605 remains within the lumen of the conduit 105 and does not enter the lumen of the blood vessel V. In this embodiment, the distal end of the distal sheath 605 remains outside the blood vessel, reducing the risk of dissection or perforation. In yet another embodiment, the arterial access device does not have a distal sheath 605 inside the conduit 105 (see FIG. 5F), and the coupler 107 at the proximal end of the conduit 105 operably couples directly with the distal connector 690 of the arterial access device. The lumen of the conduit 105 maintains its maximum size without any flow resistance due to the presence of a small tube within its lumen.

[0110] FIG. 8C shows a conduit 105 with a coupler 107 at its proximal end that can be coupled directly to a blood vessel and coupled to an arterial access device 110 of a retrograde system. As described elsewhere herein, the conduit 105 can be part of a retrograde shunt circuit without a sheath extending into its lumen. Thus, the conduit 105 can take the place of an access sheath and be directly connected to a retrograde shunt circuit, and can be configured to insert an interventional device into a blood vessel without the use of a traditional access sheath (e.g., an 8Fr sheath). The coupler 107 of the conduit 105 can be a simple luer fitting (see FIG. 5C) or the coupler 107 can be a multi-port device (see FIG. 8C) with a rotating hemostatic valve 670 (valve 670) at each port. Any of a variety of hemostatic coupling configurations are contemplated herein to provide fluid communication between the retrograde shunt circuit and the lumen of the conduit 105 such that retrograde flow through the common carotid artery (CCA) can be directed out through the arterial access device 110 and one or more devices or fluids can be provided to the common carotid artery (CCA) or beyond.

[0111] The hemostatic valve 670 (e.g., a passive valve such as a Tuohy valve) may be configured as an integrated hub or hemostatic valve 670. The hemostatic valve 670 provides hemostasis without the need to insert a specific sheath into the conduit 105. The integrated hub or hemostatic valve 670 may also cooperate with a clamp to provide hemostasis during insertion and removal of large diameter tools. A primary port with an insert for small diameter access, or a small diameter adapter 1155, may be used to increase the utility of the assembly in small diameter applications. A second port, such as a Y-port 1120, may provide additional opportunities to reverse blood flow or use other surgical instruments. The integrated hub or hemostatic valve 670 may be attached directly to the conduit 105. The integrated hub or hemostatic valve 670 may be attached to the distal tubular body 1605 via adhesive and / or overmolding. The integrated hub or hemostatic valve 670 may be a passive hemostatic valve with a self-sealing polymer valve. The integrated hub or hemostatic valve 670 may be an active Tuohy valve, such as to allow passage of a delivery device and / or sheath that has the potential to restrict blood flow. The integrated hub or hemostatic valve 670 may be a combination of active and / or passive valves. The integrated hub or hemostatic valve 670 may be coated with silicone or another suitable polymer or plastic. The integrated hub or hemostatic valve 670 may include a second port (Y-port 1120), such as for purging, degassing, backflow, or other uses. The integrated hub or hemostatic valve 670 may have an insert, such as a hubbed insert or small bore adapter 1155, to facilitate access to small bore as well as sheath / pigtail and wire delivery. The second port may be configured as a Y-port 1120.

[0112] [Venous return device] 9A-9D, the venous return device 115 may include a distal sheath 910 and a flow channel 915 that connects to the shunt 120 to form a shunt limb of the shunt 120 during use of the system. The distal sheath 910 is configured to be introduced into a venous return location, such as the jugular or femoral vein, through an incision or puncture. The distal sheath 910 and the flow channel 915 may be permanently attached or may be attached using a conventional luer fitting, as shown in FIG. 9A. Optionally, the distal sheath 910 may be coupled to the flow channel 915 by a Y-connector 1005, as shown in FIG. 9B. The Y-connector 1005 may include a hemostasis valve 1010.

[0113] The venous flow device also includes a venous sheath dilator 1015 and introducer guidewire 611 to facilitate introduction of the venous flow device into the internal jugular vein or other vein. Like the arterial access dilator (dilator 645), the venous sheath dilator 1015 includes a central guidewire lumen so that a venous sheath and dilator combination may be placed over the guidewire 611. Optionally, the venous sheath (distal sheath 910) may include a flush line 1020 with a stopcock 1025 at its proximal or distal end.

[0114] An alternative configuration is shown in Figures 9C and 9D. Figure 9C shows the components of the venous return device 115, including the venous return sheath (distal sheath 910), venous sheath dilator 1015, and sheath guidewire 611. Figure 9D shows the venous return device 115 assembled for insertion over the sheath guidewire 611 into a central vein. Once the sheath is inserted into the vein, the dilator and guidewire are removed. The venous sheath may include a hemostatic valve 1010 and a flow channel 915. A stopcock 1025 at the end of the flow channel allows the venous sheath to be flushed through the flow channel prior to use. This configuration allows the sheath to be prepared from a single point, similar to a conventional introducer sheath. Connection to the shunt 120 is made using a connector 1030 on the stopcock 1025.

[0115] To reduce flow resistance throughout the system, the arterial access channel 615 (FIG. 5A) and the venous return channel 915, as well as the Y-connector 620 (FIG. 5A) and the Y-connector 1005 (FIG. 9B), may each have a relatively large inner diameter (typically in the range of 0.100 inches to 0.200 inches) and a relatively short length (usually in the range of 10 cm to 20 cm). Low flow resistance in the system is desirable because it can maximize flow during the portion of the procedure where the risk of emboli is highest. Low flow resistance in the system also allows for the use of variable flow resistance to control flow within the system, as described in more detail below. The dimensions of the venous return sheath (distal sheath 910) may be approximately the same as those described for the arterial access sheath (distal sheath 605) above. An extension of the hemostatic valve 1010 is not required in the venous return sheath.

[0116] [Retrograde shunt] The shunt 120 may be formed of a single tube or multiple connected tubes that provide fluid communication between the arterial access device 110 (arterial access catheter) and the venous return catheter (venous return device 115) and provide a path for retrograde blood flow therebetween. As shown in FIG. 1A, the shunt 120 connects at one end (via a connector at connection location 127a) to a flow path 615 of the arterial access device 110 and at the other end (via a connector at connection location 127b) to a flow path 915 of the venous return catheter (venous return device 115).

[0117] In one embodiment, the shunt 120 may be formed of at least one tube in communication with the flow control assembly 125. The shunt 120 may have any structure that provides a fluid pathway for blood flow. The shunt 120 may have a single lumen or multiple lumens. The shunt 120 may be removably attached to the flow control assembly 125, the conduit 105, the arterial access device 110, and / or the venous return device 115. Prior to use, a user may select a length of the shunt 120 that is most suitable for use at the arterial access and venous return locations. In one embodiment, the shunt 120 may include one or more extension tubes that may be used to vary the length of the shunt 120. The extension tubes may be modularly attached to the shunt 120 to achieve a desired length. The modular nature of the shunt 120 allows a user to lengthen the shunt 120 as needed depending on the venous return site. For example, some patients may have small and / or tortuous internal jugular veins (IJVs). This site may be at higher risk of complications than other sites due to its proximity to other anatomical structures. Furthermore, hematomas in the neck may lead to airway obstruction and cerebrovascular complications. Therefore, for such patients, it may be desirable to place a venous return site at a location other than the internal jugular vein (IJV), such as the femoral vein. A femoral venous return site can be performed percutaneously, which has a lower risk of serious complications, and also provides alternative venous access to central veins when the IJV is unavailable. Furthermore, femoral venous return changes the layout of the retrograde shunt, allowing the shunt control device to be located closer to the interventional "working area" where the device is introduced and the contrast injection port is placed.

[0118] In one embodiment, the shunt 120 has an inner diameter of 4.76 mm (3 / 16 inches) and a length of 40-70 cm. As previously mentioned, the length of the shunt is adjustable. In one embodiment, the connectors between the shunt and the arterial and / or venous access devices are configured to minimize flow resistance. In one embodiment, the arterial access device 110 (arterial access sheath), retrograde shunt 120, and venous return device 115 (venous return sheath) are combined to create a low flow resistance arteriovenous AV shunt as shown in Figures 1A-1D. As previously mentioned, the connections and flow paths of all these devices are optimized to minimize or reduce flow resistance. In one embodiment, the AV shunt has a flow resistance that allows a maximum of 300 mL / min flow when no device is present in the arterial access device 110 (arterial access sheath) and the AV shunt is connected to a fluid source with blood viscosity and a static pressure head of 60 mmHg. The actual shunt resistance will vary depending on the presence or absence of a check valve or filter and the length of the shunt, and may allow flow rates of 150-300 mL / min.

[0119] When a device such as a stent delivery catheter is present within the arterial sheath, the flow resistance increases in a portion of the arterial sheath, thus increasing the flow resistance across the AV shunt. This increased flow resistance results in a corresponding decrease in flow. In one embodiment, a Y-arm (Y-connector 620) as shown in FIG. 5A connects the arterial sheath body (distal sheath 605) to a flow path 615 some distance from a hemostasis valve 625 where the catheter is introduced into the sheath. This distance is set by the length of the proximal extension 610. Thus, the portion of the arterial sheath restricted by the catheter is limited to the length of the sheath body (distal sheath 605). The actual flow restriction depends on the length and inner diameter of the sheath body (distal sheath 605) and the outer diameter of the catheter. As mentioned above, the length of the sheath body (distal sheath 605) is in the range of 5 cm to 15 cm, usually 10 cm to 12 cm, and the inner diameter is usually in the range of 7 Fr (1 Fr = 0.33 mm) to 10 Fr, usually 8 Fr. The size of the stent delivery catheter may be in the range of 3.7 Fr to 5.0 Fr, or in the range of 3.7 Fr to 6.0 Fr, depending on the size and manufacturer of the stent. This limitation can be further alleviated by designing the portion of the sheath body other than the intravascular portion (the stepped sheath body) to have a larger inner diameter, as shown in Figure 5B. Since the flow restriction is proportional to the fourth power of the lumen distance, a small increase in the lumen area or annular area significantly reduces the flow resistance.

[0120] The presence of the conduit 105 further reduces flow resistance in the retrograde blood flow system 100, particularly when the conduit 105 is coupled directly to the distal coupler (distal connector 690) of the arterial access device 110 (arterial access system) and the arterial access device 110 (arterial access system) lacks the distal sheath 605, or when the conduit 105 is coupled directly to a retrograde shunt without an arterial access device 110 (arterial access system). As discussed elsewhere herein, the inner diameter of the conduit 105 can be very large (i.e., about 5 mm to 6 mm) compared to the inner diameter (e.g., 2.3 mm to 3.0 mm) of an interventional device such as a stent delivery catheter or even an arterial access sheath designed to enter a vascular lumen. This size range of the conduit 105 can facilitate reasonably rapid anastomosis times and provide an inner diameter sufficient for delivery of devices having a variety of sizes. Conduit 105 significantly reduces flow resistance through the retrograde circuit compared to an 8Fr or 10Fr arterial sheath. The inner diameter of the flow path proximal to conduit 105 can be enlarged as well, resulting in a significant increase in retrograde flow through the system while at the same time increasing safety for patients who present with difficult anatomy for sheath insertion.

[0121] The flow control assembly and the regulation and monitoring of countercurrent flow through the system are described in detail in U.S. Patent Application Publication No. 2019 / 0125512, which is incorporated herein by reference.

[0122] [Example of usage] Entry into the common carotid artery (CCA) may be made by a transcarotid approach by surgical resection. The conduit 105 may be provided with a coupler 107 integral with the proximal end of the conduit 105 or the coupler 107 may be attached to the proximal end of the conduit 105 during surgery. The conduit 105 may be attached to the common carotid artery (CCA) using any of a variety of standard surgical techniques for end-to-side ligation or anastomosis, as discussed elsewhere herein. The conduit 105 may be prepared by cutting the distal end region to the desired overall length. The incision through the distal end region of the conduit 105 may be at an angle, such as an oblique angle, to the longitudinal axis of the lumen through the conduit 105, thereby forming a toe and heel portion at the distal end of the conduit 105. An arteriotomy may be made at a target location in the wall of the exposed common carotid artery (CCA) to form a hole of the desired size. The length of the arteriotomy may be 1.5 times the diameter of the conduit 105. In other embodiments, an incision may be made in the vessel wall and the incision may be enlarged to become a hole. In one embodiment, the hole may be approximately 5 mm to 6 mm along its largest dimension. The distal end of the conduit 105 may be sutured to the vessel wall surrounding the hole using any of a variety of suturing techniques to form a sealed connection between the distal end of the conduit 105 and the vessel wall. As discussed above, the arteriotomy may be formed through the conduit 105 already attached to the vessel wall, thereby providing a bloodless / clampless anastomosis. The sutures for coupling the conduit 105 to the vessel may be pre-placed and / or may incorporate one or more attachment mechanisms to reduce bleeding and promote a quicker anastomosis, such as a hood, gasket, sewing ring, or other distal mechanism on the conduit.

[0123] 10A-10E, the flow through the carotid bifurcation at different stages of the method of the present disclosure is described. The distal sheath 605 of the arterial access device 110 may be introduced into or placed in fluid communication with the common carotid artery (CCA) via the conduit 105. In some embodiments, the distal end of the distal sheath 605 is inserted into the lumen of the conduit 105 through the coupler 107. The distal end of the distal sheath 605 may be inserted beyond the distal end of the conduit. Preferably, the distal end of the distal sheath 605 does not exit the distal end of the conduit 105 into the vascular lumen, but instead remains within the conduit 105. In other embodiments, the arterial access device 110 does not have a distal sheath 605 and couples directly to the coupler 107 without any tubular configuration extending into the lumen of the conduit 105. After the arterial access device 110 is placed in fluid communication with the common carotid artery (CCA) via the conduit 105, blood flow proceeds in the antegrade direction AG, with flow from the common carotid artery entering both the internal carotid artery (ICA) and the external carotid artery (ECA), as shown in FIG. 10A. In yet another embodiment, the arterial access device 110 is not integrated into the system. The distal end of the conduit 105 is coupled directly to a reservoir, and the proximal end of the conduit 105 is attached to a retrograde circuit, such as via a coupler 107. This embodiment maximizes the lumen size of the entire circuit.

[0124] Next, a venous return device 115 is inserted into a venous return site, such as the internal jugular vein (IJV) or femoral vein (not shown in FIGS. 10A-10E). A shunt 120 is used to connect the flow paths 615, 915 of the arterial access device 110 (or the coupler 107 of the conduit 105 in an embodiment without the arterial access device 110) to the venous return device 115, respectively (see FIG. 1A). In this manner, the shunt 120 provides a pathway for backflow from the conduit 105, the arterial access device 110 (if present) to the venous return device 115. In another embodiment, as shown in FIG. 1C, the shunt 120 is connected to an external reservoir 130 rather than to the venous return device 115.

[0125] Once all components of the system are in place and connected, flow through the common carotid artery (CCA) is stopped, typically by using a tourniquet 2105 or other external vascular occlusion device to occlude the CCA. At that point, retrograde flow RG from the external carotid artery (ECA) and internal carotid artery (ICA) begins and flows through the conduit 105 (distal sheath 605, if present), the flow path 615 (if present), the shunt 120 (if present), and into the venous return device 115 via the flow path 915. The flow control assembly 125 regulates retrograde flow as described above. FIG. 10B illustrates the occurrence of retrograde flow RG. While retrograde flow is maintained, an interventional tool 2110 may be introduced into the vessel, as shown in FIG. 10C. The interventional tool 2110 may be introduced through the hemostasis valve 625 and the proximal extension 610 (not shown in FIGS. 10A-10E) of the arterial access device 110. The interventional tool 2110 may be introduced directly into the vessel through the coupler 107 of the conduit 105 without insertion through the arterial access device 110. FIG. 10D shows the interventional tool 2110 being a stent delivery catheter advanced into the internal carotid artery (ICA) with a stent 2115 deployed at bifurcation B. The interventional tool may also be an angioplasty catheter, an aspiration catheter, or any of a variety of interventional devices for treating either the carotid artery, the internal carotid artery, or various cerebral vessels. The conduit 105 may provide an access port for procedures other than transcarotid artery revascularization (TCAR) and neurovascular procedures. For example, the conduit 105 may be attached to the common carotid artery (CCA) to facilitate delivery of devices directed to the proximal common carotid artery (CCA), within the aorta, and elsewhere for treatment of innominate artery ostial lesions, delivery of stent grafts in the aorta (TEVAR), delivery of valves to the aortic root (TAVR), etc. These procedures may require larger devices that would benefit from entering the vessel through a conduit, as opposed to a traditional 8Fr access sheath. The conduit provides safer access to the proximal common carotid artery (CCA), brachiocephalic artery, aorta, and other locations with efficient and easy access.The larger size of direct vascular access provides particular advantages for insertion of catheters and instruments, which tend to be larger and tend to impede flow through conventionally sized sheaths, reducing the effectiveness of backflow embolic protection.

[0126] The retrograde flow rate may be increased during periods of high risk of embolic events, such as while the stent delivery catheter (interventional tool 2110) is being introduced and, optionally, while the stent 2115 is being deployed. The rate of retrograde flow may also be increased during balloon placement and expansion for pre- or post-stent deployment. Atherectomy may be performed prior to placing the stent under retrograde flow. The conduit 105 may improve the fluid dynamics for the deployment of such devices by providing a larger internal dimension than a conventional access sheath.

[0127] Further optionally, after the stent 2115 has been expanded, bifurcation B may be flushed by cycling the flow backward between low and high flow rates. The area in the carotid artery where the stent was deployed or other procedure was performed may be flushed with blood before re-establishing normal blood flow. In particular, a balloon catheter or other occlusion element may be advanced into the internal carotid artery and deployed to completely occlude that artery while the common carotid artery remains occluded. The common carotid artery may be occluded using an external occlusion mechanism such as a tourniquet 2105. The same maneuver may also be used to perform post-deployment stent expansion. This is currently typically done with self-expanding stent procedures. Flow from the common carotid artery to the external carotid artery may then be re-established by temporarily opening the occlusion means present in the artery. The resulting flow may thus flush the common carotid artery where slow, turbulent, or stagnant flow was seen during carotid occlusion to the external carotid artery. Additionally, the same balloon may be placed distal to the stent during the backward and forward flow, followed by temporary relief and flushing of the occlusion of the common carotid artery. Thus, a flushing action occurs in the stented area, helping to remove loose or loosely attached embolic debris in that area.

[0128] If necessary, steps can be taken to further loosen emboli from the treatment area while flow from the common carotid artery continues and the internal carotid artery remains blocked. For example, mechanical elements can be used to flush or remove loose or loosely attached plaque or other potential embolic debris within the stent, thrombolysis catheters or other fluid delivery catheters can be used to flush the area, or other procedures can be performed. For example, treatment of in-stent restenosis using balloons, atherectomy, or multiple stents can be performed under reverse flow. In another example, an occlusion balloon catheter can include a flow lumen (flow channel) or aspiration lumen (suction channel) that opens proximal to the balloon. Saline, thrombolytic agents, or other fluids can be injected, and blood and debris can be aspirated into or out of the treatment area without the need for additional devices. Emboli released in this way flow into the external carotid artery, which is generally less susceptible to embolic release than the internal carotid artery. The risk of emboli release is further reduced by prophylactically removing any remaining potential emboli when flow is restored to the internal carotid artery. Emboli can also be released under retrograde flow, allowing them to flow through the shunt 120 to the venous system, a filter within the shunt 120, or to an external reservoir 130.

[0129] After the bifurcation is cleared of emboli, the tourniquet 2105 (or occlusion element 129 on the distal sheath 605, if applicable) can be released and antegrade flow can be re-established as shown in FIG. 10E. The distal sheath 605 can then be removed from the conduit 105, or, if no distal sheath 605 is used in the system, the proximal coupler (Y-adapter 660) can be disconnected from the coupler 107 on the conduit 105. The conduit 105 can be removed from the vessel after use, such as by removing the sutures attaching the distal end of the conduit 105 to the vessel wall and closing the hole through the vessel wall with a suture or another closure method. The vessel may be temporarily clamped proximal and distal to the vessel hole to stop blood flow while the vessel hole is closed. Alternatively, the conduit 105 can be closed, such as using a suture closure technique, such as via a pre-placed / pre-sewn suture positioned near the distal end region of the conduit 105.

[0130] The conduit 105 can provide an access port for procedures other than stent placement. For example, the conduit 105 can be attached to the common carotid artery (CCA) to facilitate delivery of a device for stent grafting in the aorta (TEVAR) or delivery of a valve to the aortic root in combination with retrograde flow (TAVR). Because the neuroprotection system can be attached directly to the conduit 105, the overall flow resistance is much lower than if an access sheath were used to deliver the device for the procedure.

[0131] FIG. 11 illustrates an interrelated embodiment of a large bore delivery system 1100 that can be adapted for use with retrograde or reverse blood circulation, as described elsewhere herein. The large bore delivery system 1100 is further configured for use with a larger bore sheath or delivery system, such as for use in certain carotid procedures, as well as access systems described in detail elsewhere herein. As previously mentioned, some carotid patients or procedures (e.g., procedures in short / deep vessels, diseased patients, dissections, patients with scar tissue, etc.) may require a larger bore sheath or delivery system and therefore a larger entry point into the carotid artery. Such patients and procedures would benefit from the use of a large bore conduit (e.g., as part of the large bore delivery system 1100).

[0132] An embodiment of a large bore delivery system 1100 is shown in Figures 11-12E. The large bore delivery system 1100 includes a conduit 105, which may be a polymer, fabric, graft, or other material as described elsewhere herein. The conduit 105 may be coupled at a proximal end to a distal tubular body 1605 via a coupler 107. The distal tubular body 1605 may be a distal sheath 605, described in more detail elsewhere herein, or may be a length of tubing that may include a polymeric material or other inorganic material. The length of tubing may be rigid or flexible. The distal tubular body 1605 may include at least a portion of a transparent or translucent material, for example, to visualize the contents of the distal tubular body 1605. The distal end of the distal tubular body 1605 is coupled to the conduit 105, and at least a portion of the proximal end of the distal tubular body 1605 is inserted into a hub assembly 1635. The hub assembly 1635 may include a hub 1135 with a side port 1134 , a hemostasis valve 670 , such as a Tuohy valve, a Tuohy knob 1140 , and a strain relief connector 1130 .

[0133] 12A-12E, the components of the large bore delivery system 1100 are shown in further detail. As shown in FIG. 12A, the conduit 105 can include inorganic or graft materials, as described in further detail elsewhere herein. As previously mentioned, the use of the large bore delivery system 1100 can improve surgical outcomes because there is no need to manipulate tissue surrounding the large bore device to control the access site. The conduit 105 can be coupled to the distal tubular body 1605 via a coupler 107, as described above. The coupler 107 can be a through-tube coupler, as shown in FIGS. 12A and 12E. Alternatively, the coupler 107 can be any suitable coupler or connector (e.g., threaded or non-threaded coupler, genderless coupler, flanged coupler, clip, clamp, etc.). The coupler 107 can be constructed of any suitable material, such as metal, plastic, polymer, bioabsorbable material, combinations thereof, etc. The conduit 105 may also provide increased assurance of the integrity of the material used to close the surgical site (ie, the conduit / graft material has greater structural integrity than the patient's tissue).

[0134] FIG. 12A shows an exploded view of the large bore delivery system 1100 including the conduit 105, coupler 107, and distal tubular body 1605 that may be connected as described above. FIG. 12A further shows an exploded view of the hub assembly 1635. The hub assembly 1635 may include a strain relief connector 1130, a hub 1135 with a side port 1134, a hemostatic valve 670 such as a silicone Tuohy valve and Tuohy knob 1140, and a small bore adapter 1155. The small bore adapter 1155 is configured to allow the large bore delivery system 1100 to be connected to a small bore sheath or device. The coupler 107 may be configured as a conduit / polymer tubing connector as shown in FIG. 12A. The coupler 107 provides a seamless transition between the conduit 105 and the distal tubular body 1605. FIG. 12E shows a close-up view of the coupler 107 configured as a through-tubing coupler. 12E, the coupler 107 has a distal end 1104 and a proximal end 1109. The coupler 107 may have a suture tab 1108 located at a point between the distal end 1104 and the proximal end 1109. The coupler 107 has a hole 1103 with a lumen that fluidly connects with the distal tubular body 1605 when the conduit 105 is coupled through the coupler 107. The suture tab 1108 is perpendicular to the hole 1103 and further includes a hole 1102 for connecting the suture tab 1108 to a blood vessel.

[0135] In some examples, such as shown in FIG. 14A, the coupler 107 may also include a side port 1134 for accessing small holes. For example, a side port 1134 for small bore access can provide greater availability of the access site, including a point for reflux. A seamless conduit 105 to distal tubular body 1605 transition allows for customization of the total length of the distal tubular body 1605, such as using less expensive materials (e.g., polymers). The distal tubular body 1605 can also facilitate improved attachment to the hub 1135 or hemostatic valve 1670. Suture tabs can provide a secondary location for stabilizing the conduit 105 assembly. The coupler 107 can provide a transition from the conduit 105 to the distal tubular body 1605 or hemostatic valve 1670. The coupler 107 may include, for example, a small bore adapter 1155 with a hub 1135, a side port 1134 for access (e.g., a 4-8F sheath, pigtail catheter, or other device) and a hemostatic valve 1670 (Tuohy valve). The side port 1134 may also be used for backflow or to provide distal occlusion. As previously mentioned, the coupler 107 may include suture tabs 1108 for securing the large bore delivery system 1100 (large bore delivery assembly) to a blood vessel.

[0136] The distal tubular body 1605 can comprise, for example, a soft polymer, and can provide an alternative site for placement of a primary or secondary clamp, such as, for example, a pinch clamp, to control blood flow into the large bore delivery system 1100, such as to initiate retrograde flow as described elsewhere herein. The distal tubular body 1605 can comprise a plastic or polymer that serves as an improved substrate for adhesively bonding to the hemostasis valve 670 or hub 1135. For example, the distal tubular body 1605 can provide a length of tubing that is attached to the hemostasis valve 670 or hub 1135 via adhesive or the like, and the arterial access device 110 can be inserted into the distal tubular body 1605, rather than attaching the arterial access device 110 directly to the hemostasis valve 670 or hub 1135. The distal tubular body 1605 can be formed of a soft polymer, and can include primary and / or secondary clamps, such as, for example, pinch, tube, or ratchet clamps, as described above, that are used to control blood flow into the large bore delivery system 1100. The distal tubular body 1605 may be lined with a secondary polymer, such as PTFE, for improved lubricity, or may be constructed with a secondary reinforcement, such as a braid or coil, for improved kink resistance. The secondary polymer may be any polymer composition suitable for providing improved lubrication. The secondary reinforcement may include rigid or flexible plastics or polymers, metals or metal alloys, or combinations of metals and polymers or plastics.

[0137] FIG. 12B is a see-through view of a hub 1135 with a side port 1134 .

[0138] FIG. 12C is a perspective view of a small bore adapter 1155. The small bore adapter 1155 includes a distal end 1156 and a proximal end 1157. The distal end 1156 couples to a large bore delivery system 1100, while the proximal end 1157 couples to a small bore sheath or device. FIG. 12D is a close-up view of the proximal end 1157 of the small bore adapter 1155, which includes a coupling channel 1158 through which the small bore adapter 1155 couples to a small bore sheath or device. For example, the arterial access device 110 may have a diameter smaller than the diameter of the distal tubular body 1605 such that the arterial access device 110 cannot couple to the distal tubular body 1605. The small bore adapter 1155 has a lumen that tapers from a smaller diameter at the proximal end 1157 to a larger diameter at the distal end 1156 , thus providing fluid communication between a small bore sheath or device and the distal tubular body 1605 .

[0139] As described elsewhere herein, the conduit 105 may be formed of an inorganic material such as a polymer or plastic. The conduit 105 may be formed of a graft material formed from tissue, such as the patient's own tissue. FIGS. 13A-13B show an interrelated embodiment of a large bore delivery system 1300 including a conduit 105 that may be formed of a graft material. As described above, the conduit 105 may be coupled to a distal tubular body 1605 via a coupler 107. The graft material may be formed of tissue and / or an inorganic material such as a polymer or plastic. The conduit 105 may be formed of polyethylene terephthalate (Dacron), a polymer, or a bioabsorbable material. The conduit 105 may be spiraled onto a straight graft for attachment to a vessel or structure accessed by the large bore delivery system 1300. The distal tubular body 1605 is further coupled to a hemostasis valve 670, such as a passive hemostasis valve as shown in FIGS. 13A and 13B. FIG. 13B shows another angle of the large bore delivery system 1300 showing the connection of the conduit 105 to the distal tubular body 1605 via the coupler 107.

[0140] 14A-14B, an embodiment of a coupler 107 is shown. The coupler 107 may be a polymeric feed-through type tubing connector as shown in the bottom of FIG. 14A and in FIG. 12E, or may be configured as a connector with a side port 1176 as shown in the top of FIG. 14A. A connector with a side port 1176 may be configured as a small bore access port to allow for the introduction of a small bore device into the large bore delivery system 1100. A connector with a side port 1176 is used to introduce another device, tool, or substance into the large bore delivery system 1100. FIG. 14B shows a see-through perspective view of a hub 1135 with a side port 1134. A hub 1135 with a side port 1134 may be configured for large or small bore access.

[0141] 15A-15B and 17A-17C show an embodiment of a vascular loop controller 1165. The vascular loop controller 1165 is used to manage a vascular loop 1168 (see FIGS. 17A-17C). The vascular loop 1168 may be a disposable, single-use vascular loop used to occlude, constrict, and / or identify blood vessels, veins, or nerves and tendons in various medical procedures as described herein. In some embodiments, there are one or more vascular loops 1168 attached to the mechanism 1565 for actuation. For example, the vascular loop 1168 may be wrapped circumferentially around at least a portion of the distal tubular body 1605. Actuation of the vascular loop 1168 may tighten the distal tubular body 1605 to stop blood flow completely, establish retrograde flow, stabilize or "lock in" the position of the device, etc. The vascular loop 1168 may be used to control bleeding by sealing the device completely or around the device. In embodiments, a knob such as the Tuohy knob 1140 or other mechanism (e.g., crank, motor, slider, handle, etc.) can be used to actuate the vascular loop 1168. In some embodiments, the vascular loop 1168 can be formed of an elastomeric material, such as silicone, that does not undergo elastic deformation within the range of movement of the vascular loop 1168. The vascular loop controller 1165 can be attached to the conduit 105, such as at the coupler 107. The conduit 105 can extend through a hole 1510 in the controller 1165 such that the knob 1140 is located above the conduit 105. The coupler 107 can be configured as a reversible clip or clamp to reversibly attach the vascular loop controller 1165 or hub 1135 to the conduit 105 or graft material and place the vascular loop controller 1165 in fluid communication with the conduit 105 or graft material. The vascular loop controller 1165 can then be used to introduce the vascular loop 1168 into the large bore delivery system 1100. Coupler 107, if reversible, provides a means for temporarily attaching vascular loop controller 1165 or hub 1135 to conduit 105 or graft material.

[0142] FIG. 16 shows an embodiment of a primary integral clamp 1127. The primary integral clamp 1127 is placed on the conduit 105 or graft material to allow the physician to completely stop blood flow during device introduction and removal, thus minimizing blood loss and establishing backflow. Moving the clamp's location from its traditional location on the patient's neck (proximal vessel) to a location on the conduit 105 improves patient comfort and reduces the risk of arterial injury or creation or dislodging of embolic material in the case of arterial disease. In some embodiments, a partially actuated clamp may be used to stabilize the position of the delivery system within the conduit 105, for example, for therapeutic device delivery. In some embodiments, the primary integral clamp 1127 may be pre-positioned on the conduit 105 or distal tubular body 1605 to stop blood flow through the conduit 105 assembly during device exchange. In some embodiments, the primary integral clamp 1127 may be used to partially clamp the conduit 105 or distal tubular body 1605 to a sheath or delivery system, such as to increase stability. The primary integral clamp 1127 may be configured as a Luer fitting, as shown in FIG. 16, or may be configured as other suitable clamps (e.g., pinch clamps, tubing clamps, ratchet clamps, vessel loops, pipe clamps, etc.).

[0143] Referring to FIG. 17A, another embodiment of a large bore delivery system 1700 incorporating the vascular loop controller 1165 described above is shown. The large bore delivery system 1700 is sized to accommodate a delivery device 1710, such as a TAVR delivery device. The system 1700 can include a hub 1135 with a side port 1134, a distal tubular body 1605, and a flushing tube 1611. In some embodiments, the side port (Y-port 1120) of the hub 1135 with side port 1134 is optional and a conduit hub 1136 is used. The delivery device 1710 is inserted into the proximal end of the hub 1135 with side port 1134. The hub 1135 with side port 1134 is connected to the distal tubular body 1605 at its distal end. At the distal point of the hub 1135 with side port 1134, proximal to the distal end of the hub 1135 with side port 1134, is a connection point for a flushing tube 1611. The flushing tube 1611 can facilitate removal of liquid or gas from the large bore delivery system 1700. The distal tubular body 1605 can then be connected at its distal end to a hub such as a vascular loop controller 1165. The conduit hub 1136 can provide a secondary seal or mechanism to provide hemostasis. In some embodiments, the secondary seal or hemostatic mechanism can be a passive design, such as a cross-cut silicone seal or a series of seals. Alternatively, the seal can be an active seal, such as a Tuohy valve. Other possible features include the hub 1135 with a side port 1134 or a small bore adapter 1155 for delivery of a small bore device or sheath, or an insert into the primary hemostatic mechanism to allow delivery of a small bore device.

[0144] The distal tubular body 1605 may be configured to attach to the vascular loop controller 1165 and provide a bridge between the conduit hub 1136 and the conduit 105. The bridge may be a graft. In some embodiments, the distal tubular body 1605 has a durometer of about 15 Shore A to about 80 Shore A. In some embodiments, the distal tubular body 1605 may have a durometer of about 10 Shore A to about 100 Shore A. In some embodiments, the distal tubular body 1605 may have a durometer of about 20 Shore A to about 90 Shore A. In some embodiments, the distal tubular body 1605 may have a durometer of about 30 Shore A to about 80 Shore A. In some embodiments, the distal tubular body 1605 may have a durometer of about 40 Shore A to about 70 Shore A. In some embodiments, the distal tubular body 1605 may have a durometer of about 50 Shore A to about 60 Shore A. In some embodiments, the portions of the distal tubular body 1605 where the vascular loop 1168 will be located after insertion may have a reduced wall thickness to facilitate actuation of the vascular loop 1168 in these regions. In some embodiments, the distal tubular body 1605 may be press fit onto the conduit hub 1136. In some embodiments, the distal tubular body 1605 may have a clamp or other connector for attachment to the conduit hub 1136 and / or graft material. In some embodiments, an adhesive or thermal bond may also be used to attach the distal tubular body 1605 to the conduit hub 1136 and / or graft material. In some embodiments, the length of the distal tubular body 1605 between the conduit hub 1136 and the vascular loop controller 1165 may be used to remove air bubbles, i.e., degas, from the implant prior to delivery of the implant. This configuration may eliminate the need for loading tubes or other features commonly used with balloon expandable valves and other conventional interventional procedures. This region of the distal tubular body 1605 also allows the user to retract the delivery device 1710 and / or sheath into the region of the distal tubular body 1605 and subsequently remove the delivery device 1710 and / or sheath to completely close the vessel loop and prevent blood loss during removal.

[0145] FIG. 17B illustrates a large bore delivery system 1700 including a conduit 105 and clamp 1116, a vascular loop controller 1165, a hub 1135 with a side port 1134, and a distal tubular body 1605. The conduit 105 may be formed of Dacron or other suitable material as described elsewhere herein. The clamp 1116 is configured to couple the conduit 105 to the vascular loop controller 1165. The clamp 1116 may be any clip or clamp, permanent or reversible, suitable for connecting the conduit to the vascular loop controller 1165. FIG. 17C illustrates an enlarged view of the distal tubular body 1605 with a delivery device 1710 inserted. A portion of the distal tubular body 1605 may function as a window to allow a user to visualize the delivery device 1710 within the distal tubular body 1605. Additionally, the user can perform blood flow control or remove air from the large bore delivery system 1700 when the delivery system is placed within the portion of the flexible tubing that forms the window 1610 .

[0146] In various examples, the description is made with reference to the drawings. However, a particular example may be practiced without one or more of these specific details or in combination with other known methods and configurations. In the description, many specific details, such as specific configurations, dimensions, processes, etc., are described to provide a thorough understanding of the examples. In some cases, well-known processes and manufacturing techniques are not described in particular detail so as not to unnecessarily obscure the description. Throughout this specification, references to "one embodiment," "one example," and the like, mean that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment or example. Thus, phrases such as "one embodiment," "one example," and the like appearing in various places throughout this specification do not necessarily refer to the same embodiment or example. Furthermore, particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more examples.

[0147] Use of relative terms throughout the description may indicate relative locations or orientations. For example, "distal" may indicate a first direction away from a reference point. Similarly, "proximal" may indicate a second direction opposite the first direction. However, such terms are provided to establish a relative frame of reference and are not intended to limit the use or orientation of the catheters and / or delivery systems to the particular configurations described in the various embodiments.

[0148] The term "about" refers to a range of values ​​that includes the specified value and that one of ordinary skill in the art would consider reasonably similar to the specified value. In embodiments, "about" refers to within a standard deviation using measurements generally accepted in the art. In embodiments, "about" refers to a range of up to + / - 10% of the specified value. In embodiments, "about" includes the specified value.

[0149] Although this specification contains many details, these should not be construed as limitations on the scope of what is claimed or what may be claimed, but as descriptions of features specific to particular embodiments. Certain features described herein in the context of separate embodiments may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may be implemented in multiple embodiments individually or in any suitable subcombination. Furthermore, although features may be described above as acting in a particular combination and initially claimed as such, in some cases one or more features from the claimed combination may be deleted from that combination and the claimed combination may be directed to a subcombination or variation of the subcombination. Similarly, although operations are shown in the figures in a particular order, this should not be understood as requiring that such operations be performed in the particular order or sequential order shown, or that all of the illustrated operations be performed, to achieve desirable results. Only some examples and embodiments are disclosed. Variations, modifications, and extensions to the described examples and embodiments, as well as other embodiments, may be made based on the disclosed content.

[0150] In the above description and in the claims, phrases such as "at least one of" or "one or more of" may be followed by a connected list of elements or features. The term "and / or" may be used with a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such phrases are intended to mean any of the listed elements or features individually or any of the listed elements or features in combination with other listed elements or features. For example, the terms "at least one of A and B," "one or more of A and B," and "A and / or B" are intended to mean "A alone, B alone, or a combination of A and B," respectively. A similar interpretation applies to lists containing more than two items. For example, the terms "at least one of A, B, and C," "one or more of A, B, C," and "A, B, and / or C" are intended to mean "A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C," respectively.

[0151] Use of the term "based on" above and in the claims is intended to mean "based at least in part on," allowing for unrecited features or elements.

Claims

1. 1. A system for accessing an artery via a transcarotid approach, comprising: an arterial access device having a distal connector, a lumen, and a hemostasis valve disposed on an opposite side of the lumen from the distal connector; a conduit having a lumen extending between a proximal end and a distal end and a coupler located at the proximal end, the distal end configured for surgical end-to-side anastomosis to a blood vessel; the distal connector of the arterial access device is configured to operably couple to the coupler at the proximal end of the conduit to fluidly connect the lumen of the arterial access device to the lumen of the conduit.

2. The conduit is a flexible tubular structure formed of a biotextile. The system of claim 1 .

3. The conduit is a vascular graft. The system of claim 1 .

4. 4. The system of claim 3, wherein the vascular graft is formed from a substrate selected from the group consisting of polyethylene terephthalate, polyester, nylon, expanded polytetrafluoroethylene, heparin-bonded ePTFE, hooded PTFE, ring-reinforced ePTFE, and hybrid woven nylon and ePTFE.

5. The lumen of the conduit has a diameter greater than about 2 mm and less than or equal to about 10 mm. The system of claim 1 .

6. The diameter of the lumen of the conduit is about 6 mm or more and about 16 mm or less. The system of claim 1 .

7. The diameter of the lumen of the conduit is about 8 mm or more and about 10 mm or less. The system of claim 1 .

8. The arterial access device further comprises a distal sheath coupled to the distal connector and extending distally therefrom; the distal sheath comprises a sheath lumen. The system of claim 5.

9. The outer size of the sheath lumen is 7 Fr or more and 10 Fr or less. The system of claim 8.

10. The outer size of the sheath lumen is 12 Fr or more and 36 Fr or less. The system of claim 8.

11. The outer size of the sheath lumen is 14 Fr or more and 20 Fr or less. The system of claim 8.

12. 9. The system of claim 8, wherein a length of the conduit from the proximal end to the distal end is greater than a length of the distal sheath such that when the distal sheath extends through the lumen of the conduit, a distal end of the distal sheath remains within the lumen of the conduit proximal to the distal end of the conduit.

13. The length of the conduit is between 5 cm and 30 cm, The length of the distal sheath is greater than or equal to 4 cm and less than or equal to 29 cm. The system of claim 12.

14. The system of claim 1 , wherein the blood vessel is a common carotid artery, a femoral artery, a radial artery, a brachial artery, an ulnar artery, or a subclavian artery.

15. and a shunt fluidly connected to the arterial access device. The system of claim 1 , wherein the shunt provides a pathway for blood to flow from the arterial access device to a return site.

16. The system of claim 15 , further comprising a flow control assembly coupled to the shunt and configured to regulate blood flow through the shunt.

17. and a suction device coupled to a port in the shunt. The system of claim 15.

18. The suction device is a syringe or a pump.

20. The system of claim 17.

19. 14. The system of claim 8, further comprising a distal adapter coupled to and extending distally from the distal sheath.

20. 1. A system for accessing an artery via a transcarotid approach, comprising: a conduit having a lumen extending between a proximal end and a distal end, the distal end configured for end-to-side surgical anastomosis to a blood vessel; a coupler disposed at the proximal end of the conduit; a shunt fluidly connected to the coupler, the lumen of the conduit being connected to a lumen of the shunt to provide a pathway for blood to flow from the conduit through the shunt to a return site.

21. a port in fluid communication with the shunt; the port is configured to connect a suction device to the shunt; 21. The system of claim 20, wherein a distal connector of an arterial access device is configured to operably couple to the coupler at the proximal end of the conduit to fluidly connect a lumen of the arterial access device to the lumen of the conduit.

22. The conduit is a flexible tubular structure formed of a biotextile.

21. The system of claim 20.

23. The conduit is a vascular graft.

21. The system of claim 20.

24. 24. The system of claim 23, wherein the conduit provides an access port for procedures in the ostium of the innominate artery, the aorta, the aortic root, the carotid artery, or the cerebrovascular system.

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