Occlusion sheath configured for percutaneous vascular access - Patent Application 20070122997

Abstract

The systems and methods are configured for vascular and / or neurointerventional procedures. The systems and methods allow safe and rapid access, including percutaneous access, to the carotid arteries, as well as cerebral or intracranial arteries, for the introduction of interventional devices, such as to treat disease conditions. The methods and devices may include vascular access and retrograde systems.

Description

[Technical Field]

[0001] The present disclosure relates generally to medical methods and devices. More specifically, the present disclosure relates to methods, systems, and devices for accessing and treating the carotid vasculature, optionally establishing retrograde blood flow during carotid stenting and other procedures. The present disclosure also relates to methods and systems for accessing and treating cerebral arterial vessels, such as for treating stroke, intracranial atherosclerosis (ICAD), transient ischemic attack (TIA), acute ischemic stroke (AIS), tandem lesions, ruptured and unruptured intracranial and extracranial aneurysm embolism, chronic occlusion, and other neurovascular disease conditions. Summary of the Invention

[0002] Methods and devices for vascular and / or neurointerventional procedures are disclosed. The systems and methods allow safe and rapid access, including percutaneous access, to the carotid arteries, as well as cerebral or intracranial arteries, for the introduction of interventional devices, such as for treating stroke and / or other disease states. The methods and devices include vascular access and retrograde systems.

[0003] In one aspect, a system for use in accessing and treating a carotid artery is disclosed, the system comprising: an outer guide sheath configured to be delivered percutaneously into a carotid artery; an inner catheter movably disposed within the outer guide sheath, the inner catheter having an expandable element disposed at a distal region of the inner catheter, the inner catheter having a lumen extending between a proximal end and a distal end adapted to receive blood flow from a common carotid artery, the outer guide sheath and the inner catheter adapted to be introduced collectively into the common carotid artery, the expandable element adapted to dilate and occlude the common carotid artery; and a locking collar disposed at a proximal region of the outer guide sheath, the locking collar adapted to rotate about an outer wall of the outer guide sheath. the locking collar having a first set of threads on an inner wall thereof that engage a second set of threads on an outer wall of the inner catheter, the locking collar rotating to engage the first set of threads with the second set of threads and fix the position of the inner catheter relative to the outer guide sheath, the inner catheter being movably positioned inside the outer guide sheath between a first position in which the outer guide sheath is positioned relative to the outer guide sheath such that a portion of the outer guide sheath covers the expandable element and constrains it in a contracted state, and a second position in which the outer guide sheath does not constrain the expandable element, and when the inner catheter is in the first position, the locking collar is aligned with the second set of threads.

[0004] Other aspects, features and advantages will become apparent from the following description of various embodiments, which illustrate, by way of example, the principles of the present disclosure. [Brief explanation of the drawings]

[0005] [Figure 1A]FIG. 1A 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 communicating with the internal jugular vein. [Figure 1B] FIG. 1B 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. 1C 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 communicating with the femoral vein. [Figure 1D] FIG. 1D is a schematic diagram of a retrograde blood flow system in which retrograde blood flow is collected in an external reservoir. [Figure 2A] FIG. 2A 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 the arterial access device. [Figure 2B] FIG. 2B 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 3] Figure 3 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 the arterial access device, and the carotid artery is occluded using a separate occlusion device. [Figure 4] Figure 4 shows a normal cerebral circulation diagram including the circle of Willis. [Figure 5] Figure 5 shows the vasculature of a patient's neck, including the common carotid artery (CCA), internal carotid artery (ICA), external carotid artery (ECA), and internal jugular vein (IJV). [Figure 6A] FIG. 6A illustrates an arterial access device useful in the methods and systems of the present disclosure. [Figure 6B] FIG. 6B shows a further arterial access device configuration with a necked-down distal end. [Figures 7A-7B] 7A and 7B show a tube that can be used in the sheath of FIG. 6A. [Figure 7C] FIG. 7C shows an embodiment of a sheath stopper. [Figure 7D] FIG. 7D shows the sheath stopper of FIG. 7C positioned on a sheath. [Figure 8A] FIG. 8A shows a further arterial access device configuration with an expandable occlusion element. [Figure 8B] FIG. 8B shows a further arterial access device configuration with an expandable occlusion element and a reduced diameter distal end. [Figure 9A-9B] 9A and 9B show a further embodiment of an arterial access device. [Figure 9C-9D] 9C and 9D show an embodiment of a valve on an arterial access device. [Figures 10A-10C] 10A-10C illustrate an embodiment of a venous return device useful in the methods and systems of the present disclosure. [Figure 11] FIG. 11 illustrates an embodiment of a venous return device useful in the methods and systems of the present disclosure. [Figure 12] FIG. 12 shows the system of FIG. 1 including a flow control assembly. [Figure 13] FIG. 13 illustrates an embodiment of a variable flow resistance component useful in the methods and systems of the present disclosure. [Figure 14] FIG. 14 illustrates an embodiment of a variable flow resistance component useful in the methods and systems of the present disclosure. [Figures 15A-15C] 15A-15C show schematic diagrams of one embodiment of a sheath 1505 configured for percutaneous access and occlusion of a blood vessel, such as an artery. [Figures 16A-16B] 16A and 16B show schematic views of the distal region of one embodiment of a sheath configured for percutaneous access and occlusion of a blood vessel. [Figures 17A-17B]17A and 17B show schematic views of the distal region of one embodiment of a sheath 1705 configured for percutaneous access and occlusion of a blood vessel. [Figure 18A] FIG. 18A shows one embodiment of a sheath having a distal umbrella element. [Figure 18B] FIG. 18B shows a cross-sectional view of the sheath of FIG. 18A. [Figures 19A-19B] 19A and 19B show another embodiment of an umbrella element on a sheath. [Figures 20A-20B] 20A and 20B show the distal region of a sheath having an expandable element such as a balloon. [Figures 21A-21B] 21A and 21B show another embodiment of a sheath that includes an expandable balloon. [Figures 22A-22C] 22A-22C show one embodiment of a sheath that includes an expandable balloon integrated within the outer wall of the sheath. [Figures 23A-23B] 23A and 23B show the proximal hub of the sheath configured to control the tension configuration of the balloon. [Figures 24A-24B] 24A and 24B show an alternative mechanism that can be coupled to the sheath to control the tension configuration of the balloon. [Figures 25A-25B] 25A and 25B show one embodiment of a sheath system that includes a balloon sheath integrated with a guide sheath. [Figures 26A-26C] 26A-26C show another embodiment of a sheath system that includes a balloon sheath integrated with a guide sheath. [Figure 27] FIG. 27 shows a schematic cross-sectional view of one embodiment of a sheath. [Figure 28] FIG. 28 shows a schematic cross-sectional view of one embodiment of a sheath. [Figures 29A-29B] 29A and 29B show one embodiment of a sheath positioned within a blood vessel. [Figure 30A-30B] 30A and 30B show one embodiment of a sheath positioned within a blood vessel. DETAILED DESCRIPTION OF THE INVENTION

[0006] The methods, devices, and systems disclosed herein establish and facilitate retrograde or reverse flow blood circulation in the region of the carotid bifurcation to limit or prevent emboli release into the cerebral vasculature, particularly into the internal carotid artery. In a non-limiting example, the methods are particularly useful for interventional procedures, such as stenting, angioplasty, atherectomy, and the like, performed through a transcarotid or transfemoral approach to the common carotid artery, either using open surgical techniques or percutaneous techniques such as a modified Seldinger technique or a micropuncture technique. Any of a wide variety of interventions can be performed in conjunction with the systems and methods described herein, including treatment of stroke, intracranial atherosclerosis (ICAD), transient ischemic attack (TIA), acute ischemic stroke (AIS), tandem lesions, ruptured and unruptured intracranial and extracranial aneurysm embolism, chronic occlusion, intravascular lithotripsy (VLI), shock wave intravascular lithotripsy (IVL), and other neurovascular disease conditions.

[0007] Access to the common carotid artery (as shown in Figure 5) is established by placing an access sheath or other tubular access cannula within the arterial lumen; typically, the distal end of the sheath is positioned proximal to the junction or bifurcation B of the common carotid artery with the internal and external carotid arteries. The percutaneous sheath may have an occlusion element, such as a compliant occlusion balloon, at its distal end. A catheter or guidewire equipped with an occlusion element, such as a balloon, may be passed through the access sheath and placed into the proximal external carotid artery (ECA) to prevent emboli from entering, although occlusion of the ECA is not usually necessary. A second return sheath is placed in the venous system, such as the internal jugular vein (IJV) or femoral vein (FV). The arterial access sheath and venous return sheath are connected to form an external arterial-venous shunt.

[0008] Retrograde blood flow can be established and adjusted to suit the patient's needs. Blood flow through the common carotid artery is occluded by an external vascular loop or tape, a vascular clamp, an internal occlusion element such as an occlusion balloon, or other type of occlusion device. 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 or reverse direction from the cerebral vessels, through the internal carotid artery, and into the venous system through the shunt.

[0009] Alternatively, the venous sheath may be omitted and the arterial sheath connected to an external collection reservoir or receptacle, where retrograde blood flow is collected. If necessary, the collected blood may be filtered and returned to the patient during or at the end of the procedure. The pressure in the receptacle may be vented to atmospheric pressure, allowing a pressure gradient to drive blood back from the cerebral vasculature to the receptacle, or the receptacle may be under negative pressure.

[0010] If necessary, to achieve or enhance retrograde blood flow from the internal carotid artery, blood 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 (i.e., distal to) the bifurcation in the internal carotid artery.

[0011] While the procedures and treatments described below are directed specifically to carotid stenting, it will be understood that the carotid access methods described herein are also useful for angioplasty, atherectomy, and other interventional procedures that may be performed in the carotid artery system, e.g., at locations near the bifurcation between the internal and external carotid arteries. Furthermore, it will be understood that some of these access, vascular closure, embolic therapy, and protection methods may also be applicable to other vascular interventional procedures, such as the treatment of acute stroke.

[0012] The disclosure herein includes several specific aspects for improving the performance of carotid access procedures, and at least most of these individual aspects and improvements may be implemented individually or in combination with one or more other improvements to facilitate and enhance the performance of a particular intervention in the carotid system.

[0013] FIG. 1A illustrates a first embodiment of a retrograde blood flow system 100. The retrograde blood flow system 100 is configured to establish and promote retrograde or reverse blood circulation in the region of the carotid bifurcation to limit or prevent emboli from being released 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, to another return site, such as another large vein or an external vessel). The retrograde blood flow system 100 includes an arterial access device 110, a venous return device 115, and a shunt 120 that provides a pathway for reverse blood flow (retrograde blood flow) from the arterial access device 110 to the venous return device 115. A flow control assembly 125 interacts with the shunt 120. The flow control assembly 125 is configured to regulate and / or monitor retrograde flow 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 inserted at least partially within the common carotid artery (CCA), and the venous return device 115 is inserted at least partially within a venous return site, such as the internal jugular vein (IJV). The arterial access device 110 and the venous return device 115 couple to the shunt 120 at connection locations 127a and 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 retrogradely, or retrogradely (RG) (FIG. 2A), from the cerebral vasculature through the internal carotid artery and shunt 120 into the venous system. The flow control assembly 125 regulates, augments, assists, monitors, and / or otherwise regulates retrograde blood flow.

[0014] 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, thereby reducing the time and difficulty of the procedure compared to, for example, a transfemoral approach. In one embodiment, the arterial distance (measured through the artery) from the arteriotomy to the target treatment site is typically 15 cm or less. In one embodiment, the arterial distance may be 5-10 cm. Furthermore, this access route reduces the risk of emboli generation when traversing diseased, angulated, or tortuous aortic arch or common carotid artery anatomy. At least a portion of the venous return device 115 is positioned within 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 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 an optional surgical approach.

[0015] 1B, arterial access device 110 accesses the common carotid artery (CCA) via a transcarotid approach, while venous return device 115 accesses a venous return site other than the jugular vein, such as a venous return site consisting of the femoral vein (FV). Venous return device 115 can be inserted into a central vein, such as the femoral vein (FV), via a percutaneous puncture in the groin.

[0016] 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 reach the target common carotid artery (CCA). The venous return device 115 can communicate with either the jugular vein (JV) or the femoral vein (FV).

[0017] FIG. 1D illustrates yet another embodiment in which a retrograde blood flow system 100 provides retrograde blood flow from the carotid artery to an external container 130 rather than through 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 retrograde blood flow 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 retrogradely from the cerebral vasculature to the external container 130. Optionally, to achieve or enhance retrograde blood flow from the internal carotid artery, flow from the external carotid artery can be blocked, typically by placing a balloon or other occlusion element in the external carotid artery just above its bifurcation with the internal carotid artery. While FIG. 1D illustrates an arterial access device 110 placed via 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 with an arterial access device 110 placed via a transfemoral approach.

[0018] Referring to the close-up view of the carotid artery in FIG. 2A, a therapeutic or interventional device, such as a stent delivery system 135 or other working catheter, may be introduced into the carotid artery through the arterial access device 110 or a percutaneous sheath, as described in detail below. The stent delivery system 135 may be used to treat plaque P, such as by placing a stent within the carotid artery. Arrow RG in FIG. 2A indicates the direction of retrograde blood flow. In an alternative embodiment, as shown in FIG. 2B, a clamp element is used to occlude the artery.

[0019] FIG. 3 illustrates an alternative embodiment in which an occlusion element 129 may be introduced into the carotid artery 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 common carotid artery in a proximal, or "downward," direction, away from the cerebral vasculature. The second, or proximal, sheath may include an inflatable balloon 129 or other occlusion element, as generally described above. The distal sheath 605 of the arterial access device 110 may then be positioned within the common carotid artery distal to the second, or proximal, sheath and oriented generally 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.

[0020] <Description of anatomical structure> [Collateral cerebral circulation] The Circle of Willis (CW) is the major arterial trunk of the brain, connecting all major arteries supplying the brain: the two internal carotid arteries (ICA) and the vertebrobasilar system. Blood is transported from the Circle of Willis to the brain by the anterior, middle, and posterior cerebral arteries. This arterial communication allows collateral circulation through the brain. This allows blood to flow through alternate routes, providing a safety mechanism in the event that one or more blood vessels supplying the brain are blocked. The brain can, in most cases, continue to receive an adequate blood supply, even if there is a blockage elsewhere 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 through multiple pathways that redistribute blood to the deprived side.

[0021] 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 considerable anatomical variation in these vessels may exist between individuals, and many of the involved vessels may be diseased. For example, some individuals lack one of the communicating arteries. If an occlusion occurs in such individuals, collateral circulation may be impaired, ischemic events may occur, and brain damage may result. Furthermore, the autoregulatory response to a decrease in perfusion pressure may include enlargement of collateral arteries, such as the communicating arteries in the Circle of Willis. This compensatory mechanism may require an adjustment period before collateral circulation reaches a level that supports normal function. This autoregulatory response may occur over a period of 15–30 seconds and is only compensated for within a specific pressure range and a specific range of flow reduction. Therefore, transient ischemic attacks may occur during this adjustment period. Prolonged, extremely high retrograde flow may result in insufficient blood flow to the patient's brain, potentially leading to intolerance, as evidenced by neurological symptoms and, in some cases, transient ischemic attacks.

[0022] Figure 4 illustrates 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 left subclavian artery (LSCA). The aorta (AO) further gives rise to the right common carotid artery (RCCA) and right subclavian artery (RSCA). The left and right common carotid arteries (CCA) give rise to the internal carotid artery (ICA), which branches into the middle cerebral artery (MCA), posterior communicating artery (PCoA), and anterior cerebral artery (ACA). The anterior cerebral artery (ACA) supplies blood to part of the frontal lobe and the striatum. The middle cerebral artery (MCA) is a large artery with tree-like branches that carries blood throughout the lateral sides of each hemisphere of the brain. The left and right posterior cerebral arteries (PCA) arise from the basilar artery (BA) and supply blood to the posterior part of the brain (occipital lobe).

[0023] Anteriorly, the circle of Willis is formed by the anterior cerebral arteries (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), which branch off the basilar artery (BA) and complete the communicating arteries posteriorly.

[0024] 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 external carotid artery (ECA) also helps supply structures of the neck and face.

[0025] [Carotid artery bifurcation] Figure 5 shows a close-up of the relevant vasculature in a patient's neck. The common carotid artery (CCA) bifurcates at bifurcation B, dividing into the internal carotid artery (ICA) and the external carotid artery (ECA). Bifurcation B is located approximately at the level of the fourth cervical vertebra. Figure 5 shows plaque P formed at bifurcation B.

[0026] As described above, the arterial access device 110 may access the common carotid artery (CCA) via a transcarotid approach. According to the transcarotid approach, the arterial access device 110 is inserted into the common carotid artery (CCA) at an arterial access location L. The insertion may be, for example, a surgical incision or puncture of the wall of the common carotid artery (CCA). Typically, there is a distance D of approximately 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 potentially cause the generation of embolic particles. To minimize the possibility of the arterial access device 110 contacting the bifurcation B, in one embodiment, only approximately 2-4 cm of the distal region of the arterial access device is inserted into the common carotid artery (CCA) during the procedure.

[0027] 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 vagus nerve. The sternocleidomastoid muscle is located in front of the carotid sheath. Percutaneous or surgical transcarotid access to the common carotid artery and internal jugular vein can be achieved through the carotid sheath between the two crests of the sternocleidomastoid muscle, just above the clavicle, taking care to avoid the vagus nerve.

[0028] At the upper end of the carotid sheath, the common carotid artery branches into the internal and external carotid arteries. The internal carotid artery continues upward without branching, entering the skull and supplying blood to the retina and brain. The external carotid artery branches to supply blood to the scalp, face, eyes, and other superficial structures. Several facial and cranial nerves intertwine before and after the artery. Additional neck muscles may overlap the bifurcation. These nerve and muscle structures are dissected and pushed aside during carotid endarterectomy to access the carotid bifurcation. In some cases, the carotid bifurcation is closer to the level of the mandible, making access more difficult and providing less room to separate the bifurcation from the various nerves that must be protected. In these cases, the risk of inadvertent nerve injury may be increased, and open endarterectomy may not be an appropriate option.

[0029] Retrograde Blood Flow System As described above, retrograde blood flow system 100 includes an arterial access device 110, a venous return device 115, and a shunt 120 that provides a pathway for retrograde blood flow from arterial access device 110 to venous return device 115. Retrograde blood flow system 100 also includes a flow control assembly 125 that interacts with shunt 120 to regulate and / or monitor retrograde blood flow through shunt 120. Exemplary embodiments of the components of retrograde blood flow system 100 will now be described.

[0030] Arterial Access Devices FIG. 6A shows an exemplary embodiment of an arterial access device 110 including a distal sheath 605, a proximal extension 610, a flow channel 615, an adapter or Y-connector 620, and a hemostatic 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 is used in conjunction with the dilator and introducer guidewire to access a blood vessel. The functionality of the arterial access device can be optimized for transcarotid access. For example, the design of the access device components can be optimized to limit potential vessel damage due to sharp insertion angles, enable atraumatic and secure sheath insertion, and limit the length of the sheath, sheath dilator, and introducer guidewire inserted into the blood vessel. The arterial access device 110 can include or comprise any of the embodiments of a percutaneous sheath described herein.

[0031] The distal sheath 605 is configured to be introduced through an incision or puncture in the wall of the common carotid artery, 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, typically 10 cm to 12 cm. The inner diameter of the distal sheath 605 ranges from 7 Fr (1 Fr = 0.33 mm) to 10 Fr, typically 8 Fr. It is desirable for the distal sheath 605 to be highly flexible while maintaining hoop strength to resist kinking or buckling, particularly when the sheath is introduced supraclavicularly and below the carotid bifurcation via a transcarotid approach. Therefore, the distal sheath 605 may be circumferentially reinforced with braid, spiral ribbon, spiral wire, cut tubing, or the like, and may have an inner liner such that the reinforcement structure is sandwiched between an outer jacket layer and an 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 reinforcing structure or material and / or the material or thickness of the outer jacket layer may vary with the length of the distal sheath 605, thereby allowing for varying flexibility along its length. In another embodiment, the distal sheath may be configured to be introduced via percutaneous puncture into a femoral artery, such as the groin, and introduced through the aortic arch (AA) to the target common carotid artery (CCA).

[0032] As shown in FIG. 6B (a close-up of the distal region 630 of the distal sheath 605), the distal sheath 605 may have a stepped or other configuration with a reduced-diameter distal region 630. The distal region 630 of the sheath may be sized for insertion into the carotid artery and typically has an inner diameter ranging from 0.085 inches (2.16 mm) to 0.115 inches (2.92 mm). The remaining proximal region of the sheath has a larger outer diameter and lumen diameter, with the inner diameter typically ranging from 0.110 inches (2.794 mm) to 0.135 inches (3.43 mm). The larger lumen diameter in 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 approximately 2 cm to 4 cm. The relatively short length of the narrowed distal region (distal section) 630 allows this section to be placed within 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. Furthermore, 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 magnitude (level) of flow resistance. Furthermore, the narrowed distal region (distal section) 630 may be more flexible, thereby allowing it to better fit the lumen of the blood vessel.

[0033] Referring again to FIG. 6A , the proximal extension 610, which is an elongate body, has a lumen continuous with the lumen of the distal sheath 605. The lumens may be joined by a Y-connector 620, which connects the lumen of the flow channel 615 to the sheath. In the assembled system, the flow channel 615 connects to a retrograde shunt (shunt 120) and forms the first shunt limb of the shunt 120 (see FIG. 1 ). The proximal extension 610 may be long enough to space the hemostatic valve 625 far enough 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 can introduce a stent delivery system or other working catheter within the proximal extension 610 and distal sheath 605 while remaining out of the fluoroscopic field of view during a fluoroscopic examination. In one embodiment, the proximal extension 610 is approximately 16.9 cm from its most distal junction with the distal sheath 605 (e.g., hemostasis valve 625) to the proximal end of the proximal extension 610. In one embodiment, the proximal extension has an inner diameter of 3.175 mm (0.125 inches) and an outer diameter of 4.445 mm (0.175 inches). In one embodiment, the wall thickness of the proximal extension is 0.635 mm (0.025 inches). The inner diameter may be, for example, in the range of 15.24 mm (0.60 inches) to 3.81 mm (0.150 inches), and the wall thickness may be in the range of 0.254 mm (0.010 inches) to 1.27 mm (0.050 inches). In another embodiment, the inner diameter may be, for example, in the range of 3.81 mm (0.150) to 6.35 mm (0.250) inches, and the wall thickness may be in the range of 0.635 mm (0.025) to 2.54 mm (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.

[0034] In one embodiment, the distance along the sheath from the hemostatic valve 625 to the distal tip of the distal sheath 605 is in the range of approximately 25 cm to 40 cm. In one embodiment, the distance is in the range of approximately 30 cm to 35 cm. With a system configuration that allows for 2.5 cm of 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 (the location of introduction of the interventional device into the access sheath) to the target site of 32-43 cm, in the range of approximately 32.5 cm to 42.5 cm. This distance is approximately one-third the distance required by the prior art.

[0035] The flush line 635 can be connected to the side of the hemostatic 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 media, 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 hemostatic valve 625 so that the tapered distal end 650 extends through the distal end of the distal sheath 605 (see FIG. 7A). The dilator 645 can have a central lumen to accommodate a guidewire. Typically, a guidewire is placed into the vessel first, and the dilator / sheath combination travels over the guidewire as it is introduced into the vessel.

[0036] Optionally, as shown in FIG. 7A , a sheath stopper 705, e.g., a tube-shaped sheath stopper, may be provided that is coaxially received on the outside of the distal sheath 605. The sheath stopper 705 is configured to function as a sheath stopper that prevents the sheath from being inserted too deeply into the blood vessel. 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 (flange 710) that engages with the adapter (Y connector 620) and a distal end 715. Optionally, as shown in FIG. 7B , the distal end 715 may be beveled. The sheath stopper 705 may serve at least two purposes. First, as shown in FIG. 7A, 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 so 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 of between 2 cm and 3 cm. In one embodiment, the sheath stopper limits 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 of between approximately 2 cm and 3 cm, or up to 2.5 cm. Second, the sheath stopper 705 engages with a pre-placed puncture closure device (if present) in the carotid artery wall, allowing the distal sheath 605 to be withdrawn without removing the closure device. The sheath stopper 705 may be fabricated from a transparent material so that the sheath body can be clearly seen beneath the sheath stopper 705. The sheath stop 705 may also be made from a flexible material, or it may include articulations or portions that increase flexibility to allow the sheath to bend as needed into place once inserted into the artery. The sheath stop may also be plastically bendable so that it can be bent into a desired shape by the user and retain that shape when released.The distal portion of the sheath stopper may be made from a harder material and the proximal portion may be made from a softer material. In one embodiment, the harder material is 85A durometer and the softer portion is 50A durometer. In one embodiment, the distal 1-4 cm of the sheath stopper 705 is harder. 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, and reassemble it onto the sheath so that a longer insertable sheath length protrudes from the sheath stopper 705.

[0037] FIG. 7C illustrates another embodiment of a sheath stopper 705 positioned adjacent to a sheath 605 having a dilator 645 disposed therein. The sheath stopper 705 is positioned adjacent to the sheath 605 within which the dilator 645 is disposed. The sheath stopper 705 in FIG. 7C can be transformed from a first shape, such as a straight shape, to a second shape different from the first shape. The sheath stopper retains the second shape until a sufficient external force acts on the sheath stopper to change shape. The second shape may be, for example, nonlinear, curved, or otherwise contoured or irregular. For example, FIG. 7C illustrates a sheath stopper 705 having multiple bends in addition to straight sections. It should be understood that FIG. 7C is merely an example, and the sheath stopper 705 may be formed with any number of bends along its longitudinal axis. FIG. 7D illustrates the sheath stopper 705 positioned on the sheath 605. The sheath stopper 705 has a greater stiffness than the distal sheath 605 so that the distal sheath 605 assumes a shape or contour that matches the contour of the sheath stopper 705 .

[0038] 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 body habits. This feature reduces the force of the sheath tip 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 before 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.

[0039] In another embodiment, as shown in FIG. 9A, the sheath stop 705 includes a distal base or flange 710 sized and shaped to distribute the force of the sheath stop over a wider area of the vessel wall, thereby reducing the risk of vessel injury or accidental insertion of the sheath stop into the vessel through an arteriotomy. The flange 710 may have a round or other atraumatic shape large enough to distribute the force of the sheath stop over a wider area on the vessel wall. In one embodiment, the flange is inflatable or mechanically expandable. For example, the arterial sheath and sheath stop can be inserted into the surgical field through a small puncture in the skin and then expanded before inserting the sheath into the artery.

[0040] The sheath stopper can include one or more notches or indentations 720 patterned in a staggered configuration along its length, increasing the sheath stopper's flexibility while maintaining axial strength to allow forward force of the sheath stopper against the arterial wall. The indentations can also be used to facilitate securing the sheath to the patient via sutures to mitigate sheath dislodgement. The sheath stopper can also include a connector element 730 at its proximal end that corresponds to features of the arterial sheath to allow the sheath stopper to be locked or unlocked from the arterial sheath. For example, the connector element may be a hub with a generally L-shaped slot 740 that corresponds to a pin 750 on the hub, creating a bayonet-mount-style connection. In this way, the sheath stopper can be securely attached to the hub, reducing the likelihood of inadvertent removal of the sheath stopper from the hub unless unlocked from the hub.

[0041] The distal sheath 605 can be configured to establish a curvilinear transition from a generally anterior-posterior approach above the common carotid artery to a generally luminal axial approach within the common carotid artery. Arterial access through the common carotid artery wall, either via direct surgical incision or percutaneous access, may typically require a larger access angle than other arterial access sites. This is due to the fact that the common carotid artery insertion site is much closer to the treatment site (i.e., the carotid bifurcation) than other access points. A larger access angle is necessary to increase the distance from the insertion site to the treatment site, allowing the sheath to be inserted the appropriate distance without the distal tip of the sheath reaching the carotid bifurcation. For example, for transcarotid access, the sheath insertion angle is typically 30-45 degrees or more, while for femoral artery access, the sheath insertion angle may be 15-20 degrees. Therefore, the sheath must bend more than typically performed with introducer sheaths without kinking or applying excessive force to the opposing arterial wall. Additionally, it is desirable that the tip of the sheath not abut or contact the arterial wall in a manner that would restrict flow into the sheath after insertion. The insertion angle of the sheath is defined as the angle between the luminal axis of the artery and the longitudinal axis of the sheath.

[0042] Another sheath configuration includes a curved dilator inserted into a straight but flexible sheath, which curves the dilator and sheath during insertion, and the sheath is flexible enough to conform to the anatomy after the dilator is removed.

[0043] In one embodiment, the sheath may incorporate puncture-capable and atraumatic tips similar to those of guidewires, eliminating the need for needle and wire exchanges currently used for micropuncture arterial access, saving time, reducing blood loss, and requiring less surgeon skill.

[0044] FIG. 8A illustrates another embodiment of an arterial access device 110. This embodiment is substantially similar to the embodiment illustrated in FIG. 6A, except that the distal sheath 605 includes an occlusion element 129 for occluding flow through, for example, the common carotid artery. If the occlusion element 129 is an inflatable structure, such as a balloon, the sheath 605 may include an inflation lumen in communication with the occlusion element 129. The occlusion element 129 may be an inflatable balloon, but may also be an inflatable cuff, a conical or other shaped circumferential element that expands radially outward to engage the inner wall of the common carotid artery and block flow therethrough, a membrane-covered braid, a slotted tube that expands when axially compressed, or a similar structure that can be deployed by mechanical means. In the case of a balloon occlusion, the balloon may be flexible, non-compliant, elastic, high-strength, or have a variety of other properties. In one embodiment, the balloon is an elastic balloon that fits closely around the circumference of the distal end of the sheath before inflation. Upon inflation, the compliant balloon expands and fits snugly against the interior wall of the common carotid artery. In one embodiment, the compliant balloon is expandable to at least twice its diameter in the non-deployed configuration, and often is deployable to at least three times its diameter in the non-deployed configuration, and more preferably to at least four times its diameter in the non-deployed configuration or more.

[0045] As shown in FIG. 8B , the distal sheath 605 with the occlusion element 129 can have a stepped or other configuration with a reduced diameter distal region 630. The distal region 630 is sized for insertion into the carotid artery, while the remaining proximal region of the sheath 605 has larger outer and luminal diameters. The lumen of the remaining proximal region of the sheath 605 typically ranges from 0.110 inches to 0.135 inches. The larger luminal diameter in the proximal region minimizes the overall flow resistance of the sheath. In one embodiment, the reduced diameter distal region 630 is approximately 2 cm to 4 cm in length. The relatively short length of the reduced diameter distal region 630 allows this section to be placed in the common carotid artery (CCA) via a transcarotid approach, reducing the risk of the distal end of the sheath 605 contacting bifurcation B.

[0046] When the sheath is inserted at an acute angle and / or the length of the sheath inserted into the artery is short, as occurs in transcarotid access procedures, the distal tip 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 within 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, like an inflatable bumper, but can still center the sheath tip away from the vessel wall. In another embodiment, an expandable mechanism is located at the sheath tip 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 shortened.

[0047] In one embodiment, occlusion of the vessel near the distal tip of the sheath may be performed from outside the vessel, for example, with a Rummel tourniquet or vessel loop near the sheath insertion site. In another embodiment, an occlusion device may be attached to the exterior of the vessel around the sheath tip, such as an elastic loop, an inflatable cuff, or a mechanical clamp that can be tightened around the vessel and the distal sheath tip. In a retrograde blood flow system, this method of vessel occlusion minimizes static blood flow regions and reduces the risk of thrombus formation. It also ensures that the sheath tip is axially aligned with the vessel and is not partially or completely blocked by the vessel wall.

[0048] Another arterial access device is shown in Figures 9A-9D. This configuration differs from the configuration described above in the way it is connected to the shunt. Figure 9A shows the components of an arterial access device 110, including an arterial access sheath (distal sheath 605), a sheath dilator 645, a sheath stopper 705, and a sheath guidewire 611. Figure 9B shows the arterial access device 110 assembled for insertion into the carotid artery over the sheath guidewire 611. After the sheath is inserted into the artery, the sheath guidewire 611 and sheath dilator 645 are removed during the procedure. In this configuration, the sheath includes 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 a Y-adapter 660 to the hemostatic valve 625, to which the flush line 635 is connected. The sheath body (distal sheath 605) is sized to be inserted into the carotid artery, and is the part that is actually inserted into the artery during use.

[0049] Instead of a Y-connector with a fluid connection terminating in a valve, the sheath is provided with a Y-adapter 660 that connects the distal portion of the sheath to the proximal extension 610. The Y-adapter may also include a valve 670 operable to open or close a fluid connection to a connector or hub 680 that may be removably connected to a fluid path, such as a shunt. The valve 670 is located immediately adjacent to the lumen of the adapter 660 that communicates with the lumen of the sheath body (distal sheath 605). Figures 9C and 9D show a cross-sectional detail of the Y-adapter 660 with the valve 670 and hub 680. Figure 9C shows the valve closed relative to the connector. The valve position in Figure 9C is during preparation of the arterial sheath. The valve is configured to prevent the possibility of air being trapped during sheath preparation. Figure 9D shows the valve open relative to the connector. The position in Figure 9D is used when 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 prime both a flush line and a flow path, instead allowing for prime from a single flush line 635 and stopcock 640. This single-point prime is more familiar and convenient for the user because it is identical to the prime of a traditional introducer sheath without a connection to a shunt line. Additionally, the lack of a flow path in the sheath makes the arterial sheath easier to handle during prime and insertion into the artery.

[0050] 9A, the sheath may also include a more distal second connector 690 separated from the Y adapter 660 by a segment of tubing 665. The purpose of this second connector 690 and tubing 665 is to limit the length of the insertable portion of the sheath 605 while allowing the valve 670 to be positioned more proximally from the distal tip of the sheath, thereby reducing the user's exposure to the radiation source when the shunt is connected to the arterial sheath during the procedure. In one embodiment, the distal connector (second connector 690) includes suture eyelets that help secure the sheath to the patient after placement.

[0051] During a transcarotid artery revascularization (TCAR) procedure, an arterial sheath 605 may be inserted into a patient's common carotid artery (CCA). 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). Blood flow through the common carotid artery (CCA) may be occluded with an external vascular loop or tape, a vascular clamp, an internal occlusion member such as a balloon, or other type of occlusion. When blood 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 retrogradely, or backward, from the cerebral vasculature. Blood from the internal carotid artery (ICA) and external carotid artery (ECA) flows retrogradely, and the system described herein allows the retrograde blood to flow through the flow controller 1130, the venous sheath 910, 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.

[0052] (venous return device) 10A and 10B, the venous return device 115 may include a distal sheath 910 and a flow channel 915 that connects to the shunt 120 to form the 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 flow channel 915 may be permanently attached or may be attached using a conventional luer fitting, as shown in FIG. 10A. Optionally, as shown in FIG. 10B, the distal sheath 910 may be coupled to the flow channel 915 by a Y-connector 1005. The Y-connector 1005 may include a hemostatic valve 1010. The venous return device also includes a venous sheath dilator 1015 and an introducer guidewire 611 to facilitate introduction of the venous return device into the internal jugular or other vein. Similar to the arterial access dilator (dilator 645), the venous sheath dilator 1015 includes a central guidewire lumen so that a venous sheath and dilator combination can be placed over the guidewire 611. Optionally, the venous sheath (distal sheath 910) can include a flush line 1020 with a stopcock 1025 at its proximal or distal end.

[0053] Another configuration is shown in Figures 10C and 11. Figure 10C shows the components of a venous return device 115, including a venous return sheath (distal sheath) 910, a venous sheath dilator 1015, and a sheath guidewire 611. Figure 11 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 before 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.

[0054] To reduce flow resistance throughout the system, the arterial access channel 615 (FIG. 6A) and venous return channel 915, as well as the Y-connector 620 (FIG. 6A) and Y-connector 1005, may each have a relatively large inner diameter (typically in the range of 0.100 inches (2.54 mm) to 0.200 inches (5.08 mm)) and a relatively short length (typically in the range of 10 cm to 20 cm). Low flow resistance in the system is desirable because it maximizes flow during portions 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. The venous return sheath does not require an extension of the hemostatic valve 1010.

[0055] (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 the flow path 615 of the arterial access device 110 and at the other end (via a connector at connection location 127b) to the flow path 915 of the venous return catheter (venous return device 115).

[0056] 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 arterial access device 110, and / or the venous return device 115. Prior to use, the user may select the shunt 120 length most appropriate for use at the arterial access and venous return locations. In one embodiment, the shunt 120 may include one or more extension tubes that can be used to vary the length of the shunt 120. The extension tubes may be modularly attached to the shunt 120 to achieve the desired length. The modular nature of the shunt 120 allows the 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). Because this site is closer to other anatomical structures, it may be at higher risk for complications than other sites. Furthermore, neck hematomas can lead to airway obstruction and cerebrovascular complications. Therefore, for such patients, it may be desirable to place a venous return site elsewhere than the internal jugular vein (IJV), such as the femoral vein. Femoral venous return sites can be performed percutaneously, with a lower risk of serious complications, and also provide alternative venous access to central veins if the IJV is unavailable. Furthermore, femoral venous return alters the layout of retrograde shunts, 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 located.

[0057] In one embodiment, the shunt 120 has an inner diameter of 4.76 mm (3 / 16 inches) and a length of 40 to 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 sheath (arterial access device 110), the reflux shunt (shunt 120), and the venous return sheath (venous return device 115) are combined to create a low flow resistance arteriovenous shunt (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 of 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 varies depending on the presence or absence of a check valve (valve 1115) and filter 1145 (see FIG. 12) and the length of the shunt, and may allow a flow rate of 150 to 300 mL / min.

[0058] The presence of a device such as a stent delivery catheter within the arterial sheath increases flow resistance in portions of the arterial sheath, thereby increasing flow resistance throughout 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. 6A 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 sheath length ranges from 5 cm to 15 cm, typically 10 cm to 12 cm, and the inner diameter typically ranges from 7 Fr (1 Fr = 0.33 mm) to 10 Fr, typically 8 Fr. Stent delivery catheter sizes may range from 3.7 Fr to 5.0 Fr, or even 3.7 Fr to 6.0 Fr, depending on the stent size and manufacturer. This limitation can be further alleviated by designing the non-intravascular portion of the sheath body (the stepped sheath body) with a larger inner diameter, as shown in Figure 6B. Because flow restriction is proportional to the fourth power of the luminal distance, a small increase in luminal or annular area can significantly reduce flow resistance.

[0059] When using an arteriovenous shunt (AV shunt), the actual flow rate through the AV shunt further depends on the patient's cerebral blood pressure and flow resistance. [Flow Control Assembly (regulation and monitoring of retrograde blood flow)] The flow control assembly 125 interacts with the retrograde shunt (shunt 120) to regulate and / or monitor the rate of retrograde blood flow from the common carotid artery to a venous return site (e.g., femoral vein, internal jugular vein) or to an external reservoir 130. In this regard, the flow control assembly 125 allows a user to achieve higher maximum flow rates than existing systems and also to selectively adjust, set, or regulate the rate of retrograde blood flow. Various mechanisms may be used to regulate the rate of retrograde blood flow. The flow control assembly 125 allows a user to configure retrograde blood flow in a manner suitable for various treatment plans, as described below.

[0060] FIG. 12 shows an example of the system 100 and a schematic diagram of a flow control assembly 125. The flow control assembly 125 is positioned along the shunt 120 so that retrograde blood flow passes through or is in communication with at least a portion of the flow control assembly 125. The flow control assembly 125 may include various controllable mechanisms for regulating and / or monitoring retrograde blood flow. The mechanisms may include, for example, one or more pumps 1110, valves 1115, syringes 1120, and / or variable flow resistance components 1125 as various means for controlling retrograde blood flow. The flow control assembly 125 may be controlled manually by a user or automatically via a controller 1130 to vary the flow through the shunt 120. For example, by varying the flow resistance, the rate of retrograde blood flow through the shunt 120 may be controlled. The controller 1130 , which will be described in more detail below, may be integrated into the flow control assembly 125 or may be a separate component that communicates with components of the flow control assembly 125 .

[0061] Additionally, the flow control assembly 125 may include one or more flow sensors 1135 and / or anatomical data sensors 1140 (described in more detail below) for sensing one or more aspects of retrograde blood flow. A filter 1145 may be positioned along the shunt 120 to remove emboli before blood is returned to the venous return site. If the filter 1145 is positioned upstream of the controller 1130, the filter 1145 can prevent blood clots from entering the controller 1130 and potentially clogging the variable flow resistance component 1125. It should be noted that the various components of the flow control assembly 125 (including the pump 1110, valve 1115, syringe 1120, variable flow resistance component 1125, sensors 1135, 1140, and filter 1145) may be positioned at various locations along the shunt 120 and upstream or downstream relative to one another. The locations of the components of the flow control assembly 125 are not limited to those shown in FIG. 12 . Furthermore, flow control assembly 125 may not necessarily include all of the components, but rather may include various subcombinations of components. For example, a syringe may optionally be used within flow control assembly 125 for purposes of regulating flow, or may be used external to the assembly for purposes other than flow regulation, such as introducing a fluid, such as a radiopaque contrast agent, into an artery in the antegrade direction through shunt 120.

[0062] Both the variable flow resistance component 1125 and the pump 1110 may be connected to the shunt 120 to control the rate of retrograde blood flow. The variable flow resistance component 1125 controls the flow resistance, and the pump 1110 provides positive displacement of blood through the shunt 120. That is, rather than relying on perfusion stump pressure and venous backpressure in the external carotid artery (ECA) and internal carotid artery (ICA) to drive retrograde blood flow, the pump may be activated. The pump 1110 may be a peristaltic tube pump or any type of pump, including a positive displacement pump. The pump 1110 may be started and stopped (manually or automatically via the controller 1130) to selectively achieve blood movement through the shunt 120 and control the flow rate through the shunt 120. Movement of blood through the shunt 120 may be achieved in other ways, including by use of the suction syringe 1120, or a suction source (e.g., a vacutainer, a backlock syringe, or wall suction, etc.) may be used. The pump 1110 is in communication with a controller 1130 .

[0063] One or more flow control valves 1115 may be positioned along the shunt pathway. The valves may be manually or automatically actuated (via controller 1130). The flow control valves 1115 may be, for example, one-way valves that prevent antegrade flow through the shunt 120, check valves, or high-pressure valves that close the shunt 120, for example, during high-pressure contrast injections (injections intended to enter the arterial vasculature in the antegrade direction). In one embodiment, the one-way valves are low-flow resistance valves, such as those disclosed in U.S. Pat. No. 5,727,594, or other low-resistance valves.

[0064] In shunt embodiments that include both a filter 1145 and a one-way check valve (flow control valve 1115), the one-way check valve (flow control valve 1115) is positioned downstream of the filter 1145. In this manner, if there is debris traveling through the shunt, the debris is captured by the filter 1145 before reaching the one-way check valve (flow control valve 1115). Many check valve configurations include a seal member that seals against a housing that contains the flow lumen. Debris can become trapped between the seal member and the housing, thereby compromising the valve's ability to seal against reverse pressure.

[0065] The controller 1130 can communicate with components of the system 100, including the flow control assembly 125, to enable manual and / or automatic adjustment and / or monitoring of retrograde blood flow through the components of the system 100 (e.g., including the shunt 120, the arterial access device 110, the venous return device 115, and the flow control assembly 125). For example, a user can actuate one or more actuators on the controller 1130 to manually control the components of the flow control assembly 125. Manual controls may include switches, dials, or similar components located directly on the controller 1130, or may include components located remotely from the controller 1130 (e.g., a foot pedal or similar device). The controller 1130 can also automatically control the components of the system 100 without requiring input from the user. In one embodiment, a user can program software into the controller 1130 to enable such automatic control. The controller 1130 can control the operation of the mechanical portions of the flow control assembly 125. The controller 1130 may include circuitry or programming that interprets the signals generated by the sensors 1135, 1140, thereby enabling the controller 1130 to control the operation of the flow control assembly 125 in response to the signals generated by the sensors.

[0066] The representation of the controller 1130 shown in FIG. 12 is for illustrative purposes only. It should be understood that the appearance and structure of the controller 1130 may be varied as appropriate. In FIG. 12, the controller 1130 is shown as being integrated into a single housing. This allows a user to control the flow control assembly 125 from a single location. It should be noted that any component of the controller 1130 may be separated into individual housings. Furthermore, FIG. 12 shows the controller 1130 and the flow control assembly 125 as separate housings. It should be noted that the controller 1130 and the flow control assembly 125 may be integrated into a single housing or separated into multiple housings or components.

[0067] [Flow Status Indicator] The controller 1130 may include one or more indicators that provide a visual and / or audio signal to the user regarding the status of retrograde blood flow. Audio prompts advantageously notify the user of the status of retrograde blood flow without the user having to visually check the controller 1130. The indicators may include a speaker 1150 and / or a light 1155, or other means, for communicating the status of retrograde blood flow to the user. The controller 1130 may communicate with one or more sensors in the system to control activation of the indicators. Alternatively, activation of the indicators may be directly tied to the user's activation of one of the flow control actuators 1165. The indicators are not limited to speakers or lights. The indicators may simply be buttons or switches that visually indicate the status of retrograde blood flow. For example, a button in a particular state (e.g., pressed or down) may visually indicate a high retrograde blood flow state (high flow rate). Alternatively, a switch or dial may be provided that points to a particular labeled flow state, providing a visual indication that retrograde blood flow is in that labeled state.

[0068] [Flow Actuator] The controller 1130 may include one or more actuators that a user can press, toggle, manipulate, or otherwise activate to adjust or monitor the retrograde blood flow rate. For example, the controller 1130 may include a flow control actuator 1165 (e.g., one or more buttons, knobs, dials, switches) that a user can activate to selectively change aspects of the retrograde blood flow. For example, in the illustrated embodiment, the flow control actuator 1165 is a knob that can be turned to various discrete positions that correspond to the controller 1130 and cause the system 100 to achieve a particular retrograde blood flow state. Retrograde blood flow states include, for example, (a) off, (b) low flow, (c) high flow, (d) suction, etc. It should be understood that these states are merely exemplary, and different states or combinations of states may be used. The controller 1130 achieves various retrograde blood flow states by interacting with one or more components of the system, including sensors, valves, variable flow resistance components, and / or pumps. It should be noted that the controller 1130 also includes circuitry and software for adjusting and monitoring the retrograde blood flow rate, thereby eliminating the need for the user to actively operate the controller 1130.

[0069] The off state corresponds to no retrograde blood flow through the shunt 120. When the user sets the flow control actuator 1165 to off, the controller 1130 shuts off valves or closes stopcocks in the shunt 120 to stop retrograde blood flow. A low-flow state corresponds to a low retrograde blood flow rate, and a high-flow state corresponds to a high retrograde blood flow rate. When the user sets the flow control actuator 1165 to a low or high flow rate, the controller 1130 interacts with components of the flow control assembly (flow control regulator) 125, including the pump 1110, valve 1115, and / or variable flow resistance component 1125, to increase or decrease the flow rate accordingly. Finally, the aspiration state corresponds to opening the circuit to a suction source (e.g., a vacutainer or aspiration unit) when active retrograde blood flow is required.

[0070] The system allows blood flow to be varied among various states, including active, passive, suction, and off states. The active state corresponds to a system that uses a means to actively drive retrograde blood flow. Such active means include, for example, a pump, syringe, or vacuum source. The passive state corresponds to when retrograde blood flow is driven by perfusion stump pressure in the external carotid artery (ECA) and internal carotid artery (ICA), and possibly venous pressure. The suction state corresponds to a system that uses a suction source (e.g., a vacutainer or suction unit) to facilitate retrograde blood flow. The off state corresponds to a state in which retrograde blood flow in the system is zero, for example, as a result of closing a stopcock or valve. Low and high flow rates can be either passive or active flow states. In one embodiment, specific values for the low and / or high flow rates (e.g., values in ml / min) can be predetermined and / or preprogrammed into the controller, eliminating the need for the user to actually set or input these values. Rather, the user simply selects "high flow" and / or "low flow" (e.g., by pressing an actuator such as a button on the controller 1130), and the controller 1130 interacts with one or more components of the flow control assembly 125 so that the flow achieves the predetermined high or low flow value. In another embodiment, the user sets or inputs values for the low and / or high flow into a controller or the like. In another embodiment, the low and / or high flow rates are not actually set. Rather, external data (e.g., data from the anatomical data sensor 1140, etc.) is used as a basis for influencing the flow rate.

[0071] The flow control actuator 1165 may be multiple actuators. For example, one actuator (e.g., a button or switch) switches the state from low to high flow, and another actuator closes and turns off the flow loop, for example, when contrast is directed antegrade into the carotid artery during contrast injection. In one embodiment, the flow control actuator 1165 may include multiple actuators. For example, one actuator may be operated to switch the flow rate from low to high, another actuator may be operated to temporarily stop the flow, and a third actuator (e.g., a stopcock) may be operated to perform aspiration using a syringe. In another example, one actuator may be operated to switch to a low flow rate and another actuator may be operated to switch to a high flow rate. Alternatively, the flow control actuator 1165 may include multiple actuators to switch the state from low to high flow, and additional actuators to fine-tune the flow rate within a range between the high and low flow rates. Such additional actuators may be used to fine-tune the flow rate within these states when switching between low and high flow rates. Thus, it should be appreciated that within each state (i.e., high flow state and low flow state), various flow rates can be set and fine-tuned. Various actuators can be used to achieve control of the flow states.

[0072] The controller 1130 or individual components of the controller 1130 may be located in various positions relative to the patient and / or relative to other components of the system 100. For example, the flow control actuator 1165 may be located near a hemostasis valve where an interventional tool is introduced into the patient to facilitate access to the flow control actuator 1165 during tool introduction. As shown in FIGS. 1A-1C , the location may vary depending on whether a transfemoral or transcarotid approach is used, for example. The controller 1130 may include a wireless connection and / or an adjustable-length wired connection to the rest of the system 100 to enable remote control of the system 100. The controller 1130 may include a wireless connection and / or an adjustable-length wired connection to the flow control assembly (flow control regulator) 125 to enable remote control of the flow control assembly (flow control regulator) 125. The controller 1130 may be integrated into the flow control assembly (flow control regulator) 125. If the controller 1130 is mechanically connected to a component of the flow control assembly 125, a tether with mechanical actuation may connect the controller 1130 to one or more components. In one embodiment, the controller 1130 may be located a sufficient distance from the system 100 so that the controller 1130 can be located outside the radiation field when using fluoroscopy.

[0073] The controller 1130 and any of its components can communicate with other components of the system (e.g., pumps, sensors, shunts, etc.) in various ways. For example, any of a variety of mechanical connections can be used to enable communication between the controller 1130 and the system components. Alternatively, the controller 1130 can communicate electronically or magnetically with the system components. Electromechanical connections can also be used. The controller 1130 can be equipped with control software that enables the controller to implement control functions using the system components. The controller itself can be a mechanical, electrical, or electromechanical device. The controller can be mechanically, pneumatically, or hydraulically actuated (e.g., in the case of solenoid actuation of flow control states), or can be electromechanically actuated. The controller 1130 can include computer functionality, computer processor functionality, memory functionality, and data storage functionality.

[0074] FIG. 13 illustrates an exemplary embodiment of a variable flow control element (variable flow resistance component 1125). In this embodiment, flow resistance through the shunt 120 can be varied by providing two or more alternative flow paths to create low-resistance and high-resistance flow paths. As shown in FIG. 13, flow through the shunt 120 passes through a main lumen 1700 and a secondary lumen 1705. The secondary lumen 1705 is longer and / or has a smaller diameter than the main lumen 1700. Therefore, the flow resistance of the secondary lumen 1705 is greater than that of the main lumen 1700. By passing blood through both the main lumen 1700 and the secondary lumen 1705, flow resistance is minimized. The pressure drop across the main lumen 1700 across the inlet and outlet of the secondary lumen 1705 allows blood to flow through both the main lumen 1700 and the secondary lumen 1705. This has the advantage of preventing blood stagnation. As shown in FIG. 14 , blocking flow through the primary lumen 1700 of the shunt 120 completely diverts flow to the secondary lumen 1705, resulting in increased flow resistance and reduced blood flow. It is understood that additional flow lumens may be provided in parallel to allow for three, four, or more separate flow resistances. The shunt 120 may be provided with a valve 1710 that controls flow to the primary lumen 1700 and the secondary lumen 1705. The position of the valve may be controlled by an actuator (e.g., a button, switch, etc.) on the housing of the flow control assembly 125. The embodiment of FIGS. 13 and 14 has the advantage of maintaining precise lumen size even at the lowest flow setting. The size of the secondary lumen may be configured to prevent thrombus formation even under minimum or prolonged flow conditions. In one embodiment, the inner diameter of the secondary lumen 1705 is approximately 1.6 mm (0.063 inches) or greater.

[0075] In one embodiment, the connectors connecting the elements of the retrograde blood flow system are large-bore quick-connect connectors. For example, as shown in FIG. 9B, a male large-bore hub 680 on a Y-adapter 660 of the arterial sheath (arterial access device 110) connects to a female corresponding hub 1320 on the arterial side of the shunt 120. Similarly, as shown in FIG. 10C, a male large-bore connector 1310 on the venous side of the shunt 120 connects to a female corresponding connector 1310 on the flow path of the venous sheath (venous return device 115). The connections are standard female and male Luer connectors or other style tubing connectors.

[0076] [Sensor] As previously mentioned, the flow control assembly 125 may include or be in communication with one or more sensors that communicate with the system 100 and / or obtain information from the patient's anatomy. Each sensor may be configured to respond to a physical stimulus (e.g., heat, light, sound, pressure, magnetism, motion, etc.) and transmit a resulting signal (output signal) for measurement, display, or operation by the controller 1130. In one embodiment, the flow sensor 1135 interacts with the shunt 120 to sense a characteristic of the flow (e.g., blood flow rate or volumetric flow rate) through the shunt 120. The flow sensor 1135 may be directly connected to a display that directly displays the volumetric flow rate or flow rate value. Alternatively, the flow sensor 1135 may transmit data to the controller 1130 for displaying the volumetric flow rate or flow rate.

[0077] The flow sensor 1135 can be of various types. It can be a mechanical device (e.g., a paddle wheel, a flapper valve, a rolling ball, or any mechanical component responsive to flow through the shunt 120). The movement of the mechanical device in response to flow through the shunt 120 can serve as a visual indication of fluid flow or can be calibrated to a scale as a visual indication of fluid flow rate. The mechanical device can also be coupled to electrical components. For example, a paddle wheel can be positioned within the shunt 120 such that fluid flow rotates the paddle wheel, and the greater the fluid flow rate, the faster the paddle wheel rotates. The paddle wheel can be magnetically coupled to a Hall Effect sensor to detect the rotational speed, which can indicate the flow rate of fluid through the shunt 120.

[0078] The system 100 is not limited to the use of a flow sensor 1135 disposed within the shunt 120 or a sensor that interacts with the venous return device 115 or the arterial access device 110. For example, the anatomical data sensor 1140 may communicate with or otherwise interact with the patient's anatomy (e.g., the patient's neurological anatomy, etc.). In this manner, the anatomical data sensor 1140 may sense a measurable anatomical characteristic that is directly or indirectly related to the rate of retrograde blood flow from the carotid artery. For example, the anatomical data sensor 1140 may measure blood flow conditions in the brain (e.g., flow velocity in the middle cerebral artery) and communicate the conditions to the display and / or controller 1130 to adjust the rate of retrograde blood flow based on predetermined criteria. In one embodiment, the anatomical data sensor 1140 comprises a transcranial Doppler ultrasound (TCD), an ultrasound test that uses reflected sound waves to assess blood flow in the brain. The use of a TCD generates a TCD signal that can be communicated to the controller 1130, which can control the rate of retrograde blood flow to achieve or maintain a desired TCD profile. The anatomical data sensor 1140 can be based on any physiological measurement, including retrograde blood flow rate, blood flow through the middle cerebral artery, a TCD signal of embolic particles, or other neuromonitoring signal.

[0079] As another safety feature, the controller 1130 includes a timer 1170 (FIG. 12) that records the time for which the flow rate has been at a high flow rate. The controller 1130 may be programmed to automatically return the system 100 to a low flow rate after a predetermined period of high flow rate (e.g., 15, 30, or 60 seconds or more). After the controller returns to a low flow rate, the user may initiate another predetermined high flow rate period, if desired. Additionally, the user may override the controller 1130 to transition the system 100 to a low (or high) flow rate as desired.

[0080] Exemplary Percutaneous Sheath Embodiments FIG. 15A shows a schematic diagram of one embodiment of a sheath 1505 configured for percutaneous access and occlusion of a blood vessel, such as an artery (e.g., the common carotid artery). The sheath 1505 (or any of the sheaths described herein) may be configured in accordance with or as a complement to the arterial access device 110 described above. The sheath 1505 has an internal lumen and a distal tip 1502. The sheath 1505 has a distal region 1510 including an expandable portion 1515 configured to expand radially outward when positioned within a blood vessel to occlude or partially occlude the blood vessel. The expandable portion 1515 includes a plurality of corrugations or other similar structures (such as an accordion-like structure or a corrugated body that expands and contracts along its length) that can transition between a contracted state and an expanded state, the expanded state being suitable for occlusion (or partial occlusion) of the blood vessel. In one embodiment, the expandable portion 1515 is a braid or mesh (such as Nitinol) with a coating, such as a polymer coating, or a fabric (such as a polymer-coated fabric) positioned on or over the braid or mesh. In any of the embodiments described herein, the sheath can have an angled shape, such as one or more bends or curves, to facilitate centering of the distal tip within the vessel. Such one or more bends can have an acute or steep angle with respect to the longitudinal axis of the sheath, or the bends can have a soft curve. Such one or more bends can be positioned at the distal tip distal to an expandable element, such as a balloon, within the balloon, or immediately adjacent to the balloon.

[0081] The expandable portion 1515 can be coupled to elongated actuator elements, such as one or more tension wires, that extend through a small or appropriately sized lumen in the wall of the sheath 1505 to the proximal end of the sheath 1505. The one or more actuator elements are coupled to a control element, such as a tension ring 1525 on a proximal hub 1525 of the sheath 1505. The proximal hub 1525 can include a flush port 1517.

[0082] The expandable portion 1515 can be transitioned between a contracted state ( FIG. 15B ) and an expanded state ( FIG. 15C ) by applying or removing tension (or compression) to the expandable portion 1515 via the actuator element 1520 and tension ring 1525. When force (tension or compression) is applied, the expandable portion 1515 radially expands into an enlarged, disc-like shape that occludes the vessel when positioned within the vessel. When the force is removed, the expandable portion 1515 relaxes and returns to flat, allowing the sheath to be removed from the vessel. Depending on the mechanism, increasing or decreasing the applied force will either occlude or unocclude the vessel.

[0083] Actuation of the tension ring 1525, such as via a screw or pulley system, can impart force (tension or compression) to the expandable portion 1515. It should be understood that other mechanisms for creating and reducing tension can also be used, such as a stretch and lock system, advancing / retracting a braid / mesh into / outside a polymer material, or other means known in the art.

[0084] 16A shows a schematic diagram of a distal region of one embodiment of a sheath 1605 configured for percutaneous access and occlusion of a blood vessel. This embodiment includes one or more wings or flaps 1610 disposed in the distal region of the sheath 1605. The flaps 1610 are attached to the outer region of the sheath 1605 at a base region 1612. One or more expandable members 1615 (such as multiple balloons) are disposed at or near the base region 1612 between the inner surface of the flaps and the outer surface of the sheath. In a contracted state, the flaps 1610 are positioned flush or substantially flush with the outer surface of the sheath 1605 such that the flaps 1610 do not contribute, or contribute minimally, to the diameter of the sheath 1605.

[0085] The flap 1610 can be transitioned to an expanded state ( FIG. 16B ), where the flap 1610 cantilevers outward from the sheath 1605. This occurs because the expandable member 1615 transitions to a larger size, pushing the flap 1610 into the expanded state. The expandable member 1615 can be transitioned to a larger size, such as by being inflated via one or more inflation lumens in the sheath 1605. To transition back to the contracted state, the expandable member 1615 is contracted to a smaller size. The flaps close, allowing the sheath to be withdrawn from the vessel. The flap 1610 may be used in combination with any of the expandable elements (such as an expandable balloon) described herein.

[0086] The flaps may be made from any of a variety of materials, such as polymeric materials, polymer-coated fabrics, or other non-porous materials, that can prevent blood from flowing through the vessel and occlude the vessel. One or more flaps may overlap each other around the circumference of the sheath, allowing for complete circumferential occlusion of the vessel.

[0087] FIG. 17A shows a schematic diagram of the distal region of one embodiment of a sheath 1705 configured for percutaneous access and occlusion of a blood vessel. This embodiment includes an expandable umbrella element 1710 (shown in phantom) in the distal region, which extends around the entire circumference of the sheath in a circular fashion. The umbrella element 1710 transitions between a contracted state, shown in FIG. 17A, and an expanded state, shown in FIG. 17B. The umbrella may be made from a variety of materials, such as Nitinol or stainless steel (frame), or a polymer, polymer-coated fabric, or other non-porous material (cover). The umbrella element 1710 includes or is attached to one or more tethers 1715 (such as wires, rods, etc.) that extend from the umbrella element 1710 to the proximal hub of the sheath 1705, and a user can actuate the tethers 1715 to control the expansion and contraction of the umbrella element 1710. The tether 1715 is actuated by pushing, twisting, screwing, or other mechanisms at the proximal hub to move the umbrella elements between expanded and contracted states. As the wires advance distally, they act to open (i.e., expand) the umbrella elements to occlude the vessel. The tether may have sufficient column strength to allow a user to push the tether so that it applies force to the umbrella elements.

[0088] In the embodiment of FIGS. 17A and 17B , the umbrella element is located on the outer surface of the sheath 1705. In the retracted, collapsed, or unexpanded state shown in FIG. 17A , the umbrella element is positioned flush or substantially flush with the outer surface of the sheath such that the umbrella element does not substantially increase the outer size of the sheath. One or more tethers 1715 can be advanced distally (to the left relative to FIGS. 17A and 17B ) to apply a force to the umbrella element. As the tethers 1715 are advanced, the distal-most tip of the umbrella element remains fixed to the sheath, while the proximal region of the umbrella element moves distally. This causes the umbrella element 1710 to radially open into a conical, bicone, or other expanded shape. The tethers can be pulled back to close the umbrella element.

[0089] FIG. 18A shows another embodiment of an umbrella element 1810 on a sheath 1805. In this embodiment, the umbrella element 1810 is disposed between an outer sheath layer 1815 and a coaxial inner sheath layer 1820, as shown in cross section in FIG. 18B. The umbrella element 1810 is attached to one or more tethers 1830, which can be advanced to slide the umbrella element distally outward from between the outer sheath layer 1815 and the coaxial inner sheath layer 1820. The umbrella element expands outward to an expanded state. Once the umbrella element 1810 is out of the sheath, the umbrella element can be made from a shape-memory wire, such as Nitinol, that expands radially outward. The tethers 1830 can be retracted, sliding the umbrella between the outer sheath layer 1815 and the coaxial inner sheath layer 1820 or by pulling it back into the sheath.

[0090] 19A and 19B show another embodiment of an umbrella element 1910 on a sheath 1905. In this embodiment, the umbrella element is composed of a frame 1920 coupled to a plurality of push wires (or the like, e.g., a plurality of rods) 1930 that extend toward a proximal hub. The metal frame 1920 and the plurality of push wires 1930 can be slidably disposed between an inner sheath layer and an outer sheath layer.

[0091] The umbrella element 1910 can be made from a deformable material such as fabric or a polymer and is disposed on the outside of the sheath 1905. The umbrella element 1910 includes a slotted track 1935. When the frame 1920 is pushed distally (via multiple push wires 1930), multiple arms of the frame 1920 are pushed out to slide along the slotted track 1935. This allows the umbrella element to expand, as shown in FIG. 19B.

[0092] 20A and 20B show the distal region of the sheath 2005. An expandable element, such as a balloon 2010, is coupled to the distal region of the sheath 2005. The balloon 2010 is shown in an expanded state in FIGS. 20A and 20B such that the balloon 2010 flares outward from the outer wall or distal edge of the sheath 2005 in a manner that allows the balloon 2010 to at least partially occlude a blood vessel. The sheath 2005 can be formed such that the inner and outer walls form an annular cavity that accommodates the balloon 2010 in a constrained or unexpanded state. Alternatively, the balloon 2010 can be constrained within the inner lumen of the sheath 2005 when constrained. In this manner, the sheath 2005 can protect the balloon 2010, such as during insertion of the sheath 2005 into a blood vessel.

[0093] Balloon 2010 can vary in configuration, for example, in one embodiment, balloon 2010 is formed solely from a compliant or malleable material that is configured to expand into a desired shape upon inflation (such as via one or more inflation lumens in sheath 2005).

[0094] In another embodiment, the balloon includes or is coupled to one or more actuating elements 2015 that can be actuated to transition the balloon to an expanded shape. The actuating elements can be, for example, wires attached to or molded into the balloon. The wires can be used to push the balloon 2010 out of a distal region of the sheath 2005, thereby inflating the balloon to an expanded state. The wires can include, for example, a shape memory material (such as Nitinol) that provides scaffolding for the desired shape of the balloon 2010 in the expanded state. The balloon can be deflated and pulled back into the sheath using the wires to transition the balloon 2010 to a constrained state, such as during withdrawal of the sheath 2005 from the vessel.

[0095] In another embodiment, the balloon 2010 is molded around one or more shape memory wires, which when expanded, cause the balloon 2010 to flare outward toward the vessel wall, and when the balloon is deflated, vacuum pressure induces the wires to retract into the sheath.

[0096] 21A and 21B show another embodiment of the distal region of the sheath 2005, including an expandable balloon 2110 formed of a compliant ring integrated into the outer wall of the sheath 2105. The balloon 2110 is a deformable annular structure extending circumferentially around the outer wall of the sheath. The sheath 2005 includes one or more inflation lumens that can be used to expand the balloon from a constrained or smaller-sized configuration (shown in FIG. 21A) to an expanded configuration (shown in FIG. 21B). The inflation lumens can be coaxial or non-coaxial with the sheath. In a manufacturing method, the balloon is attached to the sheath 2005 using a laser bonding process. A laser is used to heat the balloon's material, fusing or bonding the balloon to the distal region of the sheath. In one embodiment, the balloon can be made of a flexible, compliant material, and the sheath can be made of a polymer.

[0097] 22A-22C illustrate another embodiment of the distal region of the sheath 2205, including an expandable balloon 2210 integrated into the outer wall of the sheath 2205. For example, the balloon 2210 may rest on the outer wall or may be at least partially disposed within the outer wall, such as between the inner and outer layers of the sheath's outer wall. The expandable balloon 2210 is coupled to the outer wall such that the balloon 2210 does not increase the diameter of the sheath when the balloon 2210 is in a contracted or unexpanded state, as shown in FIG. 22A. The balloon 2210 is made of a compliant material that can stretch along the longitudinal axis of the sheath 2205, as shown in FIG. 22A, which illustrates the balloon 2210 in a stretched state (stretched along the length of the sheath). This stretched configuration eliminates or reduces folds or waves in the balloon. The stretched configuration also places tension 2210 on the balloon such that the outer diameter of the balloon 2210 (and sheath 2205) is reduced or minimized, such as during insertion of the sheath 2205 into a blood vessel.

[0098] 22B, by releasing or otherwise removing tension on the balloon 2210, the length of the balloon 2210 along the longitudinal axis of the sheath 2205 becomes shorter than the stretched configuration shown in FIG. 22A. With the balloon 2210 in its untensioned state, the material of the balloon 2210 is allowed to expand radially outward. The balloon 2210 is then inflated (such as via one or more inflation lumens in the sheath 2205), which allows the balloon 2210 to transition to an expanded state with a larger outer diameter, as shown in FIG. 22C.

[0099] 22A can be achieved in a variety of ways. For example, the outer portion of the sheath 2205 can be pulled back proximally (as shown by arrow 2215), thereby pulling and stretching the attached portion of the balloon 2210. The outer portion of the sheath 2205 can then be secured in place using a locking element, such as a latch, screw, lock, hook, or the like, located on the proximal hub of the sheath 2205.

[0100] Non-limiting examples of mechanisms that may be coupled to the sheath 2205 to control the tension configuration of the balloon 2210 will now be described. FIG. 23A shows a first mechanism 2305 incorporated into or otherwise coupled to the proximal hub 2302 of the sheath 2205, which includes an inner shaft 2310 and a coaxial outer shaft 2315 that is slidable relative to the inner shaft 2310. The hub 2302 includes a first component 2320 attached to the outer shaft 2315 and a second component 2325 attached to the inner shaft 2310. A sealing element 2330, such as an O-ring, provides a sealed relationship between the first component 2320 and the second component 2325. The balloon is attached to the outer shaft 2315 at a proximal end and to the inner shaft 2310 at a distal end, such that relative movement between the inner shaft 2310 and the outer shaft 2315 can place the balloon 2210 in a stretched configuration. Hub 2302 also includes an inflation passage 2335 that can be used to inflate balloon 2210 .

[0101] FIG. 23B shows a perspective view of the second component 2325. The second component 2325 has an elongate body 2340 slidably disposed within a cavity 2345 ( FIG. 23A ) in the first component 2320, allowing the second component 2325 to slide along the longitudinal axis of the sheath 2205 relative to the first component 2320, as represented by arrow A in FIG. 23A . Referring to FIG. 23B , the body 2340 of the second component 2325 has a path of travel 2350 in which the pin 2355 of the first component 2320 is disposed. The path of travel 2350 and the pin 2355 are engaged with one another such that the path of travel 2350 and the pin 2355 collectively define slidable movement between the first component 2320 and the second component 2325.

[0102] Before the balloon 2210 is inflated, the hub 2302 is actuated by moving the first component 2320 relative to the second component 2325. This can cause relative movement between the inner shaft 2310 (attached to the balloon 2210) and the outer shaft 2315 (also attached to the balloon 2210) such that a user can selectively place the balloon 2210 in a tensioned configuration (as shown in FIG. 22A) or an untensioned configuration (as shown in FIG. 22B). When the balloon 2210 is in the untensioned configuration, it can be inflated via inflation passage 2335.

[0103] 24A and 24B (not to scale) illustrate alternative mechanisms that may be coupled to the sheath 2205 to control the tension configuration of the balloon 2210. FIG. 24A illustrates the balloon 2210 in a deflated state, and FIG. 24B illustrates the balloon 2210 in an expanded state. The hub 2405 is located in a proximal region of the sheath 2205 and includes an access device, such as a Luer element 2415, that provides access to the interior lumen of the sheath 2205. The hub 2405 includes a first hub portion 2420 attached to the inner shaft 2310 and a second hub portion 2425 attached to the outer shaft 2315 of the sheath 2205. The inner shaft 2310 is attached to the distal end of the balloon 2210. The outer shaft 2315 is attached to the proximal end of the balloon 2210.

[0104] The second hub portion 2425 is slidably disposed within the internal cavity of the first hub portion 2420. The second hub portion 2425 is movable within the cavity along the longitudinal axis of the sheath 2205. The second hub portion 2425 divides the internal cavity into a proximal portion 2435 and a distal portion 2440. A biasing element, such as a spring 2440, is disposed within the second hub portion 2425 and biases the second hub portion 2425 toward the proximal portion 2435 of the internal cavity. A seal may be disposed to provide a sealed separation between the proximal portion 2435 and the distal portion 2440. Additionally, an inflation shaft 2450 communicates with the proximal portion 2435 and the balloon 2210.

[0105] The spring 2440 applies a constant tension to the outer shaft 2315 via the second hub portion 2425 so that the balloon 2210 is maintained in a default, deflated state as shown in FIG. 24A . In this state, the balloon 2210 is stretched along its length. The balloon 2210 can be inflated via the inflation shaft 2450, which causes the balloon 2210 to expand outward and retract the outer shaft 2315 proximally as shown in FIG. 24B . Inflation of the balloon via the inflation shaft 2450 also increases the pressure in the cavity 2435, which acts like a piston on the second hub portion 2425, causing the second hub portion 2425 to slide downward as permitted by the spring 2440. Then, to operate, the air pressure on the second hub portion 2425 is appropriately balanced (and exceeds) the resistive spring force of the spring 2440. Additionally, the inflation shaft 2450 can be used to inject fluids such as water / saline / contrast into the inflation lumen (between the outer and inner shafts) and the balloon 2210.

[0106] 25A and 25B illustrate one embodiment of a sheath system including an inner balloon sheath 2505 (or balloon catheter 2505) integrated with an outer guide sheath 2510. The guide sheath 2510 is coaxially and slidably disposed over the balloon sheath 2505 such that the balloon sheath is slidably and removably disposed inside the inner lumen of the guide sheath. The balloon sheath 2505 includes an expandable element, such as a balloon 2515, that can transition between a contracted state and an expanded state. The balloon 2515 extends circumferentially around the outer wall of the sheath. FIG. 25A illustrates the system in a first state or position, where the guide sheath 2510 is positioned relative to the balloon sheath 2505 such that a portion of the guide sheath 2510 covers the balloon 2515, restraining it in the contracted state. That is, the guide sheath 2510 covers the balloon 2215 such that the inner wall of the guide sheath 2510 restricts the balloon 2215 from expanding outward. The inner catheter 2505 includes a lumen extending between a proximal end and a distal end, the distal end adapted to receive blood flow from the common carotid artery. The outer guide sheath and inner catheter 2505 are adapted to be introduced together through a puncture in the common carotid artery or another artery, such as the femoral artery. Any of the embodiments described herein can be introduced through the common carotid artery, femoral artery, or other artery.

[0107] FIG. 25B shows the system in a second state or position, in which the guide sheath 2510 has been moved axially (along the long axis of the sheath, such as proximally or to the right relative to FIG. 25B) relative to the balloon sheath 2505 (or vice versa) so that the guide sheath 2510 no longer covers or constrains the balloon 2515. Relative movement between the guide sheath and balloon sheath can be achieved by movement of the guide sheath alone, the balloon sheath alone, or both the guide sheath and the balloon sheath. The distal edge of the guide sheath 2510 is thus positioned proximal to the proximal edge of the balloon 2515 in FIG. 25B. The balloon 2515 is free to expand outward, such as via inflation, via a self-biasing force toward expansion, or via some other mechanism. The balloon sheath 2505 can include a locking element, such as a threaded structure 2520, that mechanically couples with a corresponding locking element 2525 (e.g., corresponding threads) on the guide sheath 2510. That is, the outer wall of the balloon sheath 2505 has one or more threads that interact with complementary threads on the inner wall of the locking element 2525 of the outer guide sheath 2510. In one embodiment, the locking element 2525 is an annular collar that has an outwardly expanded size relative to at least a portion of the outer guide sheath 2510, such as an adjacent region of the outer guide sheath 2510 where the collar is disposed. The collar can rotate about the outer wall and / or longitudinal axis of the outer guide sheath 2510 relative to the remainder of the outer guide sheath 2510. This allows a user to rotate the locking element 2525 and lockably engage the threads of the guide sheath with the threads of the inner balloon catheter 2505. Thus, the locking collar has a first set of threads on its inner wall that engage a second set of threads on the outer wall of the inner catheter to fix the position of the inner catheter relative to the outer guide sheath. In one embodiment, the locking collar is aligned with the second set of threads on the guide sheath when the inner catheter is in the first position.In another embodiment, there is a third set of threads on the guide sheath (or a continuous thread configuration along the inner catheter), and the locking collar is aligned with the threads when in the second position.

[0108] Figure 25B shows the guide sheath 2510 positioned such that the guide sheath's locking elements 2525 lock with the balloon sheath's threads 2520 (Figure 25A). When in the configuration shown in Figure 25A, the guide sheath 2510 can also protect the balloon 2515, for example, during passage through tissue. As described above, the collar 2525 can be rotated to engage the threads, locking the relative positions of the guide sheath and balloon catheter together.

[0109] 26A-26C illustrate another embodiment of a sheath system including a balloon sheath 2605 (or catheter) integrated with a guide sheath. Referring to FIG. 26A, the sheath 2605 includes a window cover 2610 aligned with an internal balloon. As described in more detail below, the window cover 2610 can be a layer of material disposed between the outer housing of the sheath 2605 and the inner layer of the sheath. FIG. 26A shows the window cover 2610 in a closed state such that the window cover 2610 covers and restrains the internal balloon. The window cover 2610 includes a proximal region 2615 that can be actuated by a user, such as by retracting the proximal region 2615. This also retracts the window cover 2610 proximally, exposing an opening in which the balloon 2620 is disposed. The balloon 2620 can then be inflated to an expanded state, as shown in FIG. 26C. A variety of mechanisms can be used to retract the window covering 2610, such as a slidable pull tab, a trigger, a screw mechanism, a button, or the like.

[0110] Figure 27 shows a schematic cross-sectional view of one embodiment of the sheath 2605 of Figures 26A-26C. The sheath 2605 includes an outer layer forming an outer housing 2705. A window layer 2710 (e.g., a polymer) is disposed inside the outer housing and forms the window covering 2610. A balloon layer 2715 is disposed inside the window layer 2710 and forms the balloon 2620. A middle layer 2720 is formed from a polymer and is disposed below the balloon layer 2715. An inflation lumen 2725 is formed between the middle layer 2720 and an inner layer 2730 and may be, for example, by a braid and / or a coil. An inner lumen 2740 is inside the sheath 2605.

[0111] Figure 28 shows a schematic cross-sectional view of another embodiment of the sheath 2605 of Figures 26A-26C. This embodiment of the sheath 2605 includes an outer layer forming an outer housing 2805. A balloon layer 2820 (e.g., a polymer) is disposed between the outer housing 2805 and a window layer 2815. An inflation lumen is disposed between the window layer 2815 and an inner layer 2825, which may be formed, for example, by a braid and / or a coil. An inner lumen 2830 is inside the sheath 2605.

[0112] A window layer 2710 (e.g., a polymer) is disposed inside the outer housing and forms the window covering 2610. A balloon layer 2715 is disposed inside the window layer 2710 and forms the balloon 2620. A middle layer 2720 is formed from a polymer and is disposed below the balloon layer 2715. An inflation lumen 2725 is formed between the middle layer 2720 and the inner layer 2730 and may be, for example, a braid and / or a coil. An inner lumen 2740 is inside the sheath 2605.

[0113] 29A and 29B show another embodiment of a sheath 2805 (or inner balloon catheter) positioned within a blood vessel. The sheath 2805 has a bent distal region, and the bend can be a fixed bend that remains in place unless acted upon to remove the bend. The bend can be the default state of the sheath, or the bend can be achieved after placement within the blood vessel. Referring to FIG. 29A, the sheath 2805 includes a main lumen 2810 that opens at the distal end of the sheath 2805. The sheath also includes a secondary lumen 2815 aligned with the main lumen 2810. The secondary lumen 2815 forms a hole or opening 2820 positioned a distance from the distal end of the sheath 2805. In an exemplary embodiment, opening 2820 is 1-5 cm from the distal end of sheath 2805, e.g., at a bend or 1-2 cm, 1-3 cm, or 2-3 cm from the distal end of sheath 2805. Inflatable balloon 2830 is adhered or otherwise fixedly positioned inside secondary lumen 2815 adjacent opening 2820. When positioned inside secondary lumen 2815 as shown in FIG. 29A , balloon 2830 is in a deflated state with a reduced size. Balloon 2830 can also be moved and positioned outside secondary lumen 2815 such that balloon 2830 is positioned flush with the outer surface of sheath 2805, thereby blocking opening 2820. Balloon 2820 can be further moved outside secondary lumen 2815 and outside sheath 2805 to engage the interior of the blood vessel and occlude or at least partially occlude the blood vessel. The balloon 2830 is made from a compliant or semi-compliant material. For example, the balloon 2830 may be made from silicone, polyblend, urethane, Pellethane, or other suitable material. The embodiment of Figures 29A-30B can be used in conjunction with the configuration shown in Figures 25A and 25B (or any other embodiment) to constrain the balloon 2830.

[0114] During insertion of the sheath 2805 into the blood vessel, the balloon 2830 is structurally protected by being inside the secondary lumen 2815 or by being taut along the outer surface of the sheath 2805. Once positioned at the desired location within the blood vessel, the balloon 2830 can be inflated to an expanded state through the secondary lumen 2815, as shown in FIG. 29B. During inflation, the balloon 2830 expands outward through the opening 2820. The balloon 2830 can be expanded to a size that occludes the blood vessel. The balloon expands proximally while the main lumen 2810 opens distally. This configuration can provide additional working space within the blood vessel. As described above, the balloon can be positioned at a bend. In one embodiment, the balloon inflates or extends outward from the sheath in a direction opposite the direction of the bend (or in a direction opposite the direction the opening of the lumen 2810 faces), as shown in FIG. 29B.

[0115] 30A and 30B show another embodiment of a sheath 3005 positioned within a blood vessel. This embodiment is similar to the embodiment of FIGS. 29A and 29B , except that the sheath 3005 may have a single lumen 3010 or dual lumens (not shown). The sheath 3005 has a distal opening 3015 at the distal end of the sheath 3005. The sheath 3005 also has a second opening 3020 that communicates with the lumen 3010 (in a single lumen configuration). The lumen 3010 can be used to deliver one or more therapies, such as, for example, a stent delivery system, an aspiration catheter, a stent retriever, etc., through the distal opening 3015.

[0116] The secondary opening 3020 can be used to deliver an occlusion device 3030, which can be mounted on a tether, delivery wire, or delivery shaft 3035, as shown in FIG. 30B. A delivery wire can be used to move a balloon in and out of the sheath 3005 through the opening 3020. The occlusion device can be any device expandable to occlude a blood vessel. The occlusion device 3030 can be positioned to occlude the blood vessel, and then a therapy is delivered through the distal opening 3015.

[0117] The occlusion device 3030 can vary in configuration. For example, the occlusion device can be a balloon on a delivery shaft 3035 formed of a thin wire or tube and hollow for inflation of the occlusion device. The delivery shaft 3035 can have a J-shaped distal region (or other shape) to facilitate passage through the minor opening 3020. The shape of the occlusion device 3030 can vary. In another example, the occlusion device 3030 is an umbrella- or accordion-like device coupled to an actuating element, such as multiple pull wires, for expansion of the occlusion device. A dilator can be used to facilitate delivery of the delivery shaft 3035. Such a dilator has an inner lumen through which the occlusion device 3030 and delivery shaft 3035 can be positioned. The dilator can be used to guide the occlusion system through the minor opening 3020, allowing the occlusion system to automatically enter the vessel and preventing it from striking the vessel wall at a sharp angle. The dilator can also include a bleed-back indicator to confirm that the occlusion system has been properly inserted into the vessel. The occlusion system shown in Figures 30A and 30B can also be delivered through the dual lumen sheath shown in Figures 29A and 29B.

[0118] (Example Usage) Flow through the carotid bifurcation at various stages of the disclosed method will now be described. First, the distal sheath 605 of the arterial access device 110 (or the percutaneous sheath of any embodiment described herein) is introduced into the common carotid artery (CCA). As previously mentioned, entry into the common carotid artery (CCA) may be via a transcarotid or transfemoral approach, and may be accomplished via either a direct surgical cut-down or percutaneous access. After the sheath 605 of the arterial access device 110 is introduced into the common carotid artery (CCA), blood flow continues 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).

[0119] Next, a venous return device 115 is inserted into a venous return site, such as the internal jugular vein (IJV) or femoral vein. A shunt 120 is used to connect to the flow path 615 of the arterial access device 110 and the flow path 915 of the venous return device 115, respectively (see FIG. 1A). In this manner, the shunt 120 provides a pathway for retrograde blood flow from the arterial access device 110 to the venous return device 115. In another embodiment, as shown in FIG. 1C, the shunt 120 is connected to an external container 130 instead of the venous return device 115.

[0120] Once all components of the system are in place and connected, blood flow through the common carotid artery (CCA) is stopped, such as by using an expandable occlusion element in a percutaneous sheath within the CCA. Alternatively, an occlusion element 129 is introduced into the distal sheath 605 of the arterial access device 110 and into a second occlusion device 112, separate from the CCA, as shown in FIG. 2B. The external carotid artery (ECA) may be occluded by a separate occlusion element, either on the same device (arterial access device 110) or on a separate occlusion device.

[0121] At that point, retrograde blood flow RG begins from the external carotid artery (ECA) and internal carotid artery (ICA), passing through the sheath 605, the flow path 615, the shunt 120, and into the venous return device 115 via the flow path 915. The flow control assembly 125 controls the retrograde blood flow as described above. While retrograde blood flow is maintained, a stent delivery catheter 2110 (or other interventional device) is introduced into the sheath 605. The stent delivery catheter 2110 is introduced into the sheath 605 via the hemostatic valve 615 and the proximal extension 610. The stent delivery catheter 2110 is advanced into the internal carotid artery (ICA), and a stent 2115 is deployed at the bifurcation B.

[0122] Optionally, if blood flow from the common carotid artery continues and the internal carotid artery remains occluded, measures may be taken to further loosen emboli from the treatment area. For example, mechanical elements may be used to flush or remove loose or loosely attached plaque or other potential embolic debris from within the stent, a thrombolysis catheter or other fluid delivery catheter may be used to irrigate the area, or other procedures may be performed. For example, treatment of in-stent restenosis with a balloon, atherectomy, or the use of an additional stent may be performed under retrograde blood flow. In another example, an occlusion balloon catheter may include a flow or aspiration lumen or channel opening proximal to the balloon. Saline, thrombolytic agents, or other fluids may be injected into the treatment area, or blood and debris may be aspirated from the treatment area, without the need for additional devices. Emboli released in this manner may flow into the external carotid artery, which is generally less susceptible to embolic release than the internal carotid artery. Prophylactic removal of any remaining potential emboli further reduces the risk of emboli being released when blood flow to the internal carotid artery is re-established. Emboli may also be released by retrograde blood flow, in which case they flow through the shunt 120 to the venous system, a filter within the shunt 120, or an external reservoir 130.

[0123] After the bifurcation is de-occluded, the occlusion element 129, or alternatively the tourniquet 2105, may be released, allowing antegrade blood flow to be re-established, as shown in Figure 14E. The sheath 605 may then be removed.

[0124] A self-closing element may be deployed around the penetration in the wall of the common carotid artery at the end of the procedure, prior to withdrawal of the sheath 605. Typically, the self-closing element is deployed at or near the beginning of the procedure; however, optionally, the self-closing element is deployed as the sheath is withdrawn, often positioned so that it is released from the distal end of the sheath onto the wall of the common carotid artery. Use of a self-closing element is advantageous because it substantially affects rapid closure of the penetration in the common carotid artery as the sheath is withdrawn. Such rapid closure can reduce or eliminate unexpected bleeding at the end of the procedure or in the event of accidental sheath dislodgement. Furthermore, such a self-closing element may reduce the risk of arterial wall dissection during access. Furthermore, the self-closing element may be configured to apply friction or other retention force to the sheath during the procedure. Such retention force may advantageously reduce the likelihood of accidental sheath dislodgement during the procedure. The self-closing element eliminates the need for vascular surgical closure of the artery with sutures after sheath removal, reducing the need for a large surgical field and significantly reducing the surgical technique required for the procedure.

[0125] Although various method and device embodiments have been described in detail herein with reference to particular versions, it should be understood that other versions, embodiments, uses, and combinations thereof are possible, and therefore the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

1. 1. A system for use in accessing and treating a carotid artery, comprising: an outer guide sheath configured to be delivered percutaneously into the carotid artery; an inner catheter movably disposed within the outer guide sheath, the inner catheter having an expandable element disposed in a distal region of the inner catheter, the inner catheter having a lumen extending between a proximal end and a distal end adapted to receive blood flow from a common carotid artery, the outer guide sheath and the inner catheter adapted to be introduced collectively into the common carotid artery, the expandable element adapted to dilate and occlude the common carotid artery; a locking collar disposed in a proximal region of the outer guide sheath, the locking collar configured to rotate about an outer wall of the outer guide sheath, the locking collar having a first set of threads on an inner wall of the locking collar that engage a second set of threads on an outer wall of the inner catheter, the locking collar rotating to engage the first set of threads with the second set of threads and fix the position of the inner catheter relative to the outer guide sheath; The inner catheter a first position in which the outer guide sheath is disposed relative to the outer guide sheath such that a portion of the outer guide sheath covers the expandable element and constrains it in a contracted state, and a second position in which the outer guide sheath does not constrain the expandable element; When the inner catheter is in the first position, the locking collar is aligned with the second set of threads.

2. further comprising a shunt fluidly connected to the inner catheter; The system of claim 1 , wherein the shunt provides a pathway for blood to flow from the inner catheter to a perfusion site.

3. The system of claim 1 , wherein the expandable element is a balloon that extends around the periphery of the outer wall of the sheath.

4. The system of claim 1 , wherein the inner catheter has a bend in a distal region of the inner catheter.

5. The system of claim 4 , wherein the expandable element is a balloon extendable out of a hole in the inner catheter, the hole being located at the bend.

6. The system of claim 5 , wherein the balloon is fixedly attached to the inner catheter near the bend, and the balloon can reside entirely within the inner catheter.

7. 7. The system of claim 6, wherein the balloon is fixedly attached to the inner catheter near the bend, the balloon can be positioned flush with an outer wall of the inner catheter, and the balloon blocks the hole at the bend.

8. 6. The system of claim 5, wherein the distal end of the inner catheter has an opening facing a first direction, and the balloon extends outside the hole in a direction opposite the first direction.

9. The system of claim 5 , wherein the balloon is positioned inside the inner catheter adjacent the opening.

10. The system of claim 5 , wherein the balloon is attached to a delivery wire.

11. The system of claim 10 , wherein the delivery wire has an inflation lumen through which the balloon can be inflated.

12. The system of claim 10 , wherein the delivery wire can be used to move the balloon in and out of the inner catheter through the opening.

13. The system of claim 5 , wherein the inner catheter has a primary lumen and a secondary lumen, and the balloon is disposed at least partially within the secondary lumen.

14. The system of claim 5, wherein the hole is located 1 to 5 cm from the distal end of the balloon catheter.

15. The system of claim 1 , wherein the outer guide sheath and the inner catheter are adapted to be introduced together through a puncture in the common carotid artery.

16. The system of claim 1 , wherein the locking collar has an expanded outer size relative to at least a portion of the outer guide sheath.

17. The system of claim 1 , wherein the system is configured to be delivered percutaneously into the carotid artery via an entry site in the femoral artery.

18. The system of claim 1 , wherein the system is configured to be delivered percutaneously into a carotid artery via an entry site in the neck.

19. The system of claim 1 , wherein the expandable element has a corrugated shape.

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