Method and system for establishing carotid artery blood flow regurgitation

Abstract

To provide devices and methods for establishing and facilitating retrograde flow blood circulation in a region of a carotid artery bifurcation in order to limit or prevent the release of emboli into a cerebral vasculature such as into an internal carotid artery.SOLUTION: A retrograde flow system 100 includes an arterial access device 110, a venous return device 115, and a shunt 120 that provides a passageway for a retrograde flow from the arterial access device 110 to the venous return device 115. A flow control assembly 125 interacts with the shunt 120. The arterial access device 110 is at least partially inserted into a common carotid artery CCA, and the venous return device 115 is at least partially inserted into a venous return site such as an internal jugular vein IJV. The arterial access device 110 and the venous return device 115 couple to the shunt 120 at connection locations 127A, 127B.SELECTED DRAWING: Figure 1A

Description

[Background technology]

[0001] Reference to related applications This application claims priority to the concurrently pending U.S. Provisional Patent Application No. 62 / 145,809 (titled “Methods and Systems for Establishing Retrograde Carotid Arterial Blood Flow,” filed April 10, 2015). Claiming priority as of the aforementioned filing date, this Provisional Patent Application is incorporated herein by reference in its entirety.

[0002] background The disclosures of this application relate, in general, to medical methods and medical devices. In particular, the disclosures of this application relate to methods and systems for accessing the carotid artery and establishing blood flow regurgitation during carotid artery stenting and other procedures.

[0003] Carotid artery disease typically consists of plaque deposits that narrow the junction between the common carotid artery (CCA) and the internal carotid artery (ICA) (Figure 5), which supply blood to the brain. These deposits generate embolic particles, increasing the risk of them entering the cerebral blood vessels and causing neurological consequences such as transient ischemic attacks (TIAs), ischemic stroke, or death. Furthermore, if such narrowing becomes severe, blood flow to the brain is obstructed, leading to serious, and often fatal, consequences.

[0004] There are two main treatment methods used to treat carotid artery disease. The first is a surgical incision called carotid endarterectomy (CEA), in which the common carotid, internal carotid, and external carotid arteries are occluded, the carotid arteries are incised at the site of the disease (usually the bifurcation where the common carotid artery (CCA) divides into the internal carotid artery (ICA) and the external carotid artery (ECA)), the plaque (P) is detached and removed, and then the carotid arteries are closed. The second method involves the placement of a stent in the carotid artery, called carotid artery stenting (CAS), which is typically placed at or across the bifurcation from the common carotid artery (CAA) to the internal carotid artery (ICA), or entirely within the internal carotid artery. Typically, a self-expanding stent is introduced into the target common carotid artery (CCA) via percutaneous puncture into the femoral artery in the groin, ascending the aortic arch.

[0005] Both of these methods expose the patient to the risk of embolisms being released into the cerebral blood vessels via the internal carotid artery (ICA). The clinical implications of embolic release into the external carotid artery (ECA), which supplies blood to the facial structures, are less significant. During CEA, the risk of embolic release into the internal carotid artery (ICA) is minimized by arterial debridement and vigorously flushing before closing the vessel and restoring blood flow. Since all carotid arteries are occluded while the arteries are incised during surgery, particles cannot enter the vessels.

[0006] During carotid artery stenting (CAS) surgery, additional embolic protection devices are typically used to reduce, at least partially, the risk of embolism. One example of such a device is a distal filter, which is deployed into the internal carotid artery distal to the stent area. The filter is intended to capture embolic particles and prevent them from passing into the cerebral blood vessels. However, such filtering devices have certain limitations. These filtering devices must advance towards the target vessel and traverse the stenosis prior to deployment, which exposes the cerebral blood vessels to a shower of emboli. It is not always easy for them to advance, deploy, and remove through narrow stenoses and / or severely angular vessels. And finally, they only filter particles larger than the filter pore size (typically 100-120 μm). Furthermore, these devices cannot filter 100% of the blood flow because the filter walls are not properly aligned, and there is also a risk of debris slipping through during filter retrieval.

[0007] Of particular interest in this disclosure is the proposed alternative method to reduce the risk of embolic discharge into the internal carotid artery (ICA) during carotid artery stenting (CAS), utilizing the concept of reversed blood flow within the ICA to prevent embolic debris from entering the cerebral vessels. Numerous specific protocols have been described, but they generally rely on inserting a sheath into the common carotid artery via the femoral artery (transfemoral access). Blood flow in the common carotid artery is typically occluded by inflating a balloon on the distal end of the sheath. Blood flow into the external carotid artery (ECA) may also typically be occluded using a balloon catheter or balloon guidewire introduced through the sheath. Subsequently, the sheath is connected to a vein or a low-pressure external receptacle to establish reverse or retrograde flow from the internal carotid artery through the sheath away from the cerebral vessels. After such reverse flow is established, stenting can be performed with a significantly reduced risk of embolic debris entering the cerebral vessels.

[0008] An alternative system to simply stopping forward blood flow in the ICA consists of a carotid access sheath equipped with two integrated balloons (an ECA occlusion balloon at the distal end and a CCA occlusion balloon placed at a certain distance from the ECA balloon). Between the two balloons is an opening for inserting interventional carotid stenting devices. This system does not allow blood to flow backward from the ICA to the venous system, but instead blocks the blood flow and removes embolic debris by aspirating before forward blood flow can be established within the ICA.

[0009] While protocols for regurgitating or halting blood flow for intravascular stenting and other interventional procedures in the carotid arteries are highly promising, such methods have generally required the manipulation of multiple separate access and occlusion components. Furthermore, these protocols are somewhat complex, requiring numerous separate steps, and their execution has been limited to only the most skilled vascular surgeons, interventional radiologists, and cardiologists. Moreover, dimensional limitations of femoral access mean that the access device itself provides very high blood flow resistance, limiting the possibility of regurgitation and / or aspiration. Additionally, the requirement to occlude the external carotid artery adds risk and complexity to the procedure. If the stent is placed across the bifurcation from the common carotid to the internal carotid artery and its removal would damage the deployed stent, the balloon catheter for occluding the external carotid artery may be trapped within the arterial wall.

[0010] None of the described brain protection devices and methods provide postoperative protection. However, the occurrence of embolic particles has been measured up to 48 hours or more after stenting. In CEA, flushing at the end of the procedure while blocking blood flow to the internal carotid artery (ICA) would help reduce postoperative embolism. A similar flushing step in CAS would also reduce the risk of embolism. Furthermore, stents designed to improve embolic particle uptake would also reduce postoperative embolism.

[0011] Furthermore, all currently available carotid artery stenting and cerebral protection systems are designed to access the carotid artery from the femoral artery. Unfortunately, the route from the femoral artery to the common carotid artery is relatively long, has several turns that are quite angular in some patients, and often contains plaque and other disease. The part of the procedure involving access to the common carotid artery from the femoral artery is difficult, time-consuming, and carries the risk of creating a shower of embolic debris from both the target and the opposite common carotid artery into the cerebral vessels. Several studies suggest that half or more of embolic complications during CAS surgery occur during access to the CCA. No protocol or system provides protection during this part of the surgery.

[0012] In recent years, Criado has proposed a retrograde protocol with an alternative access route to the carotid artery. This alternative route consists of direct surgical access to the common carotid artery (CCA) and is called transcervical or transcarotid access. Transcervical access significantly reduces the length and twists of the path from the access point to the vessel to the target treatment site, thereby mitigating the time and difficulty of the procedure. Furthermore, this access route reduces the risk of embolism from the navigation of diseased, angular, or tortuous aortic arch or common carotid artery anatomy.

[0013] The Criado protocol is described in several publications of medical literature cited below. As shown in Figure 3, the Criado protocol uses a flow shunt containing an arterial sheath 210 and a venous sheath 212. Each sheath has side arms 214 and is terminated with a stopcock 216. The two sheath stopcocks are connected by a connector tube 218, thereby completing a regurgitant shunt from the arterial sheath 210 to the venous sheath 212. The arterial sheath is placed in the common carotid artery (CCA) through a surgical incision opened in the neck below the bifurcation of the carotid artery. Occlusion of the common carotid artery (CCA) can be achieved using temporary vessel ligation, e.g., a Rummel tourniquet and umbilical tape, or a vessel loop. A venous return sheath 212 is also placed in the internal jugular vein (IJV) (Figure 3) via an open surgical incision. Then, reflux from the internal carotid artery (ICA) and external carotid artery (ECA) will be established by opening the stent 216. The Criado protocol is an improvement over the earlier reflux protocol because it does not require femoral access. Thus, potential complications associated with femoral access are completely avoided. Furthermore, the lower flow restrictions provided by the shorter access route offer an opportunity for a more vigorous reflux velocity, increasing the efficiency of embolic debris removal. These reduced flow restrictions will allow the desired reflux of the internal carotid artery (ICA) to be established without the need for external carotid artery (ECA) occlusion, as required in the earlier protocol.

[0014] While significantly improved compared to femoral access-based regurgitation protocols, the Criado protocol and blood flow shunts can still benefit from advancements. In particular, existing arterial and venous sheaths used during surgery still have significant blood flow limitations in the side arms 214 and plugs 216. Reverse flow circuit resistance is maximized when the intervention catheter is inserted into the arterial access sheath. In some percentage of patients, the perfusion pressure in the external carotid artery (ECA) is greater than that in the internal carotid artery (ICA). In these patients, this pressure difference may drive antegrade blood flow from the ECA to the ICA. Regurgitation shunts with low blood flow resistance have been able to ensure regurgitation in both the ECA and ICA despite the pressure gradient from the ECA to the ICA.

[0015] Furthermore, there is no means to monitor or adjust the regurgitation velocity. The ability to increase and / or adjust the blood flow velocity would give the user the ability to set an optimal regurgitation velocity for the patient's tolerance and physiology as well as the stage of the surgery, thereby providing advanced protection from embolic debris. Moreover, the system described by Criado relies on manually turning one or more plugs to open and close the regurgitation shunt, for example, while injecting contrast agent to facilitate the placement of the CAS system. Finally, the Criado protocol relies on occlusion of a surgical incision of the common carotid artery via a vascular loop or Rummel hemostatic device. A system with means to occlude the common carotid artery in the vessel (e.g., with an occlusion element on the arterial access sheath) would allow the entire procedure to be performed using percutaneous techniques. A percutaneous approach not only allows non-surgical physicians to perform the procedure but also limits the size of the surgical incision and the associated complications.

[0016] For these reasons, it is desirable to provide improved methods, devices, and systems for transcervical access, regurgitation, and flushing procedures, and for inserting carotid stents into the carotid arteries, in order to reduce the risk of surgical and postoperative embolization, improve the level of hemostasis throughout the procedure, and improve the ease and speed of carotid stent placement. These methods, devices, and systems would simplify the procedure performed by the physician, while reducing the risk of improper procedure and / or insufficient regurgitation and flushing for protection against embolic discharge. The system would provide individual devices and components that are easy to use with one another and prevent embolism-related complications. These methods and systems would also provide convenient and convenient automatic closures for some or all arterial penetrations to prevent unintended blood loss at the end of the procedure. Furthermore, these systems, devices, and methods would be suitable for use via either surgical incision or percutaneous intravascular access routes. Furthermore, this method, apparatus, and system will enable the insertion of prosthetic implants into blood vessels, thereby reducing postoperative complications. At least some of these objectives will be achieved by the present invention as described below in this specification. [Overview of the project]

[0017] The disclosed methods, apparatus, and systems establish and facilitate the retrograde flow of blood circulation within the carotid bifurcation region to restrict or prevent the release of embolus into the cerebral blood vessels, particularly into the internal carotid artery. This method is particularly useful for interventions performed in the common carotid artery via a transcervical or transfemoral approach, such as stent placement and angioplasty, atherectomy, and employs either surgical incision or percutaneous techniques, such as the modified Seldinger technique or micropuncture techniques.

[0018] Access to the common carotid artery (Figure 5) is established by inserting a sheath or other tubular access cannula into the lumen of the artery, typically having the distal end of the sheath positioned near the junction or bifurcation B (Figure 5) of the common carotid artery into the internal and external carotid arteries. The sheath may have an occlusion member (e.g., a compliant occlusion balloon) at its distal end. An occlusion member such as a balloon may be placed through the access sheath and positioned proximal to the external carotid artery (ECA) to prevent the embolus from entering the external carotid artery, although occlusion of the external carotid artery is usually not essential. A second return sheath is placed in the venous system (e.g., the internal jugular vein (IJV) or femoral vein (FV)). The arterial access sheath and the venous return sheath are connected to form an external arteriovenous shunt.

[0019] The regurgitation is established and adjusted to meet the patient's needs. Blood flow through the common carotid artery is blocked by either an external vascular loop or an internal occlusion device such as tape, vascular clamps, or a balloon, or any other type of occlusion means. When blood flow through the common carotid artery is blocked, the natural pressure gradient between the internal carotid artery and the venous system will result in reverse blood flow from the cerebral blood vessels through the internal carotid artery and through the shunt to the venous system.

[0020] Alternatively, the venous sheath can be removed, and the arterial sheath can be connected to an external collection reservoir or receptacle. The backflowed blood can be collected in this receptacle. If necessary, the collected blood can be filtered and returned to the patient during or at the end of surgery. The pressure in the receptacle can accept atmospheric pressure, creating a pressure gradient that causes reverse blood flow from the cerebral blood vessels to the receptacle, or the pressure in the receptacle can be negative.

[0021] Optionally, to achieve or enhance retrograde flow from the internal carotid artery, typically, a balloon or other occlusive element may be deployed just above (i.e., distal to) the bifurcation with the internal carotid artery in the external carotid artery to block blood flow from the external carotid artery.

[0022] The techniques and protocols described below are particularly directed to carotid artery stenting, but it will be recognized that the methods of accessing the carotid artery described herein are also useful in angioplasty, atherectomy, and other interventional procedures performed in the carotid artery system, particularly in locations near the bifurcation between the internal carotid artery and the external carotid artery. Further, it will be well understood that some of those access methods, vascular occlusion methods, and embolism prevention methods are applicable to other vascular interventional procedures (such as the treatment of acute stroke).

[0023] The disclosure of the present application includes many specific aspects for improving the performance of carotid artery access protocols. To facilitate and enhance the performance of specific interventions in the carotid artery system, at least most of these individual aspects and improvements can be performed individually or in combination with one or more other improvements.

[0024] In one aspect, a system for access to and treatment of the carotid artery is disclosed. The system includes an arterial access device suitable for introduction into the common carotid artery and receiving blood flow from the common carotid artery, a shunt fluidly connected to the arterial access device and providing a path for blood flow from the arterial access device to a return site, and a flow control assembly coupled to the shunt and suitable for regulating blood flow between at least a first blood flow state and at least a second blood flow state through the shunt, the flow control assembly including one or more components that interact with the blood flow through the shunt.

[0025] In another aspect, a system for access to and treatment of the carotid artery is disclosed. The system includes an arterial access device suitable for introduction into the common carotid artery and receiving blood flow from the common carotid artery, a shunt fluidly connected to the arterial access device and providing a path for blood flow from the arterial access device to a return site, a flow mechanism coupled to the shunt and suitable for changing blood flow between a first blood flow rate and a second blood flow rate through the shunt, and a controller that automatically interacts with the flow mechanism to regulate blood flow between the first blood flow rate and the second blood flow rate through the shunt without requiring input from a user.

[0026] In yet another embodiment, a device used for accessing and treating the carotid artery is disclosed. The device includes a distal sheath having a distal end, a proximal end, and a lumen extending between the distal and proximal ends, suitable for introduction into the common carotid artery; a proximal extension having a distal end, a proximal end, and a lumen between them, wherein the distal end of the proximal extension is connected to the proximal end of the sheath at a junction such that the lumens of the proximal extension are contiguous; a flow line having a lumen, connected near the junction so that blood flowing into the distal end of the sheath can flow into the lumen of the flow line; and a hemostatic valve at the proximal end of the proximal extension, suitable for restricting blood flow from the proximal extension while allowing catheter introduction into the distal sheath through the proximal extension.

[0027] In another embodiment, a method for accessing and treating a carotid artery is disclosed. This method includes the steps of forming a penetration into the wall of the common carotid artery, positioning an access sheath through the penetration, blocking blood flow from the common carotid artery through which the sheath has passed, enabling blood flow in reverse from the carotid artery to the sheath and from the sheath to a return site via a flow path, and modifying the blood flow through the flow path based on feedback data.

[0028] In another embodiment, a method for accessing and treating a carotid artery is disclosed. This method includes the steps of forming a penetration in the wall of the common carotid artery, positioning an access sheath through the penetration, blocking blood flow from the common carotid artery through which the sheath has passed, enabling blood flow from the carotid artery to the sheath and from the sheath to a return site via a blood flow path, and monitoring blood flow through the blood flow path.

[0029] In another embodiment, a method for accessing and treating the carotid artery is disclosed. The method includes the steps of forming a penetration in the wall of the common carotid artery, positioning an arterial access sheath through the penetration, blocking blood flow from the common carotid artery through which the sheath passes, enabling blood flow to flow backward from the internal carotid artery to the sheath while keeping the common carotid artery blocked, and adjusting the state of the blood flow flowing backward through the sheath.

[0030] In another embodiment, a method for accessing and treating a carotid artery is disclosed. This method includes the steps of forming a penetration in the wall of the common carotid artery, positioning an arterial access sheath through the penetration, blocking blood flow from the common carotid artery through which the sheath has passed, allowing blood flow to flow backward from the internal carotid artery to the sheath while keeping the common carotid artery blocked, and adjusting the velocity of the blood flow backward from the sheath to a level that is tolerable to the patient, wherein the adjusted velocity is the baseline.

[0031] This application relates to U.S. Patent No. 8,157,760 (titled "Methods and Systems for Establishing Retrograde Carotid Arterial Flow") and U.S. Patent Application No. 14 / 227,585 (titled "Methods and Systems for Establishing Retrograde Carotid Arterial Blood Flow"), both of which are incorporated herein by reference.

[0032] Other features and advantages will become apparent from the following description of various embodiments illustrated for illustrative purposes and for the purpose of illustrating the principles of the invention. [Brief explanation of the drawing]

[0033] [Figure 1A]Figure 1A is a schematic diagram of a retrograde blood flow system including a blood flow control assembly, where the arterial access device accesses the common carotid artery via a transcervical approach, and the venous return device is connected to the internal jugular vein.

[0034] [Figure 1B] Figure 1B is a schematic diagram of the retrograde blood flow system, in which the arterial access device accesses the common carotid artery via a transcervical approach, and the venous return device is connected to the femoral vein.

[0035] [Figure 1C] Figure 1C is a schematic diagram of a retrograde blood flow system, in which the arterial access device accesses the common carotid artery via a transfemoral approach, and the venous return device is connected to the femoral vein.

[0036] [Figure 1D] Figure 1D is a schematic diagram of a retrograde blood flow system, where the retrograde flow is collected at an external receptacle.

[0037] [Figure 1E] Figure 1E is a schematic diagram of an alternative, retrograde blood flow system, in which the arterial access device accesses the common carotid artery via a transcervical approach, and the venous return device is connected to the femoral vein.

[0038] [Figure 2A] Figure 2A is a magnified view of the carotid artery, which is occluded by an occlusion element on the sheath and connected to a retrograde shunt, and an intervention device (e.g., a stent delivery system or other working catheter) is introduced into the carotid artery via an arterial access device.

[0039] [Figure 2B] Figure 2B shows an alternative system in which the carotid artery is occluded by a separate external occlusion device and connected to a retrograde shunt, and an intervention device (e.g., a stent delivery system or other working catheter) is introduced into the carotid artery via an arterial access device.

[0040] [Figure 2C] Figure 2C shows an alternative system in which the carotid artery is connected to a retrograde shunt, an intervention device (e.g., a stent delivery system or other working catheter) is introduced into the carotid artery via an arterial access device, and the carotid artery is occluded by a separate occlusion device.

[0041] [Figure 2D] Figure 2D shows an alternative system in which the carotid artery is occluded, the artery is connected to a regurgitation shunt via an arterial access device, and an intervention device (e.g., a stent delivery system) is introduced into the carotid artery via a separate arterial introducer device.

[0042] [Figure 3] Figure 3 shows a conventional Criado blood flow shunt system.

[0043] [Figure 4] Figure 4 shows a diagram of normal cerebral circulation, including the ring of Willis.

[0044] [Figure 5] Figure 5 shows the blood vessels in the patient's neck, including the common carotid artery (CCA), internal carotid artery (ICA), external carotid artery (ECA), and internal jugular vein (IJV).

[0045] [Figure 6A] Figure 6A illustrates an arterial access device useful for the method and system disclosed herein.

[0046] [Figure 6B] Figure 6B shows an additional arterial access device structure with a reduced diameter distal end.

[0047] [Figure 7A-B] Figures 7A and 7B illustrate tubes useful for the sheath shown in Figure 6A.

[0048] [Figure 7C] Figure 7C shows an embodiment of the sheath stopper.

[0049] [Figure 7D] Figure 7D shows the sheath stopper shown in Figure 7C attached to the sheath.

[0050] [Figure 7E-F] Figures 7E and 7F show the adaptable sheath stopper during use.

[0051] [Figure 7G] Figure 7G shows an embodiment of a sheath with a flexible distal section and a sheath stopper for use.

[0052] [Figure 8A] Figure 8A shows an additional arterial access device structure with an expandable occlusion element.

[0053] [Figure 8B] Figure 8B shows an additional arterial access device structure with an expandable occlusion element and a reduced distal end.

[0054] [Figure 9A-B] Figures 9A and 9B show additional embodiments of the arterial access device.

[0055] [Figure 9C-D] Figures 9C and 9D show embodiments of valves on arterial access devices.

[0056] [Figure 10A-D] Figures 10A to 10D show embodiments of venous return devices useful for the methods and systems disclosed herein.

[0057] [Figure 11]Figure 11 shows the system from Figure 1, including the blood flow control assembly.

[0058] [Figure 12A-B] Figures 12A-12B show embodiments of variable flow resistance components useful for the methods and systems disclosed herein.

[0059] [Figure 13A-C] Figures 13A-13C show embodiments of a blood flow control assembly within a single housing.

[0060] [Figure 14A-E] Figures 14A-14E show a typical blood flow path during a procedure to insert a stent into a carotid artery bifurcation according to the principles disclosed herein.

[0061] [Figure 15A-D] Figures 15A-15D show typical kit and package shapes. [Modes for carrying out the invention]

[0062] Detailed explanation Figure 1A shows a first embodiment of the reflux system 100, which is suitable for establishing and facilitating reflux of blood circulation within the region of the carotid bifurcation in order to limit or prevent the release of embolus into the cerebral blood vessels (particularly the internal carotid artery). The system 100 interacts with the carotid artery to provide reflux from the carotid artery to a venous return site, such as the internal jugular vein (or another superior vena cava or, in an alternative embodiment, another return site such as an external receptacle). The reflux system 100 includes an arterial access device 110, a venous return device 115, and a shunt 120 that provides a reflux passage from the arterial access device 110 to the venous return device 115. A blood flow control assembly 125 interacts with the shunt 120. As will be described in more detail below, the blood flow control assembly 125 is suitable for regulating and / or monitoring reflux from the common carotid artery to the internal jugular vein. The blood flow control assembly 125 interacts with the blood flow paths via the shunt 120, either one or both of the internal and external blood flow paths. As described in more detail below, the arterial access device 110 is inserted at least partially into the common carotid artery (CCA), and the venous return device 115 is inserted at least partially into a venous return site such as the internal jugular vein (IJV). The arterial access device 110 and the venous return device 115 are coupled to the shunt 120 at coupling positions 127a, 127b. If 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 the reverse direction (RG) (Figure 2A) from the cerebral blood vessels through the internal carotid artery and the shunt 120 to the venous system. The blood flow control assembly 125 regulates, augments, assists, monitors, and / or otherwise modulates the regulating blood flow.

[0063] In the embodiment shown in Figure 1A, the arterial access device 110 accesses the common carotid artery (CCA) via a transcervical approach. The transcervical access provides a short, uncurved 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 from the incised artery (arteriotomy) to the target treatment site (measured by the distance traveled through the artery) is 15 cm or less. In another embodiment, the distance is 5 to 10 cm. Furthermore, this access route reduces the risk of embolism from diseased, angular, or curved aortic arch or common carotid artery tissue. At least a portion of the venous return device 115 is placed in the internal jugular vein (IJV). In one embodiment, transcervical access to the common carotid artery is achieved percutaneously via a skin incision or puncture into which the arterial access device 110 is inserted. If an incision is used, the length of the incision can be approximately 0.5 cm. An occlusion element 129, such as an expandable balloon, can 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 can be placed 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 transcervical approach. In the surgical approach, the common carotid artery can be occluded using a hemostatic device 2105. To indicate that it is a device used in any surgical approach, the hemostatic device 2105 is illustrated with a dashed-dotted line (phantom).

[0064] In another embodiment shown in Figure 1B, the arterial access device 110 accesses the common carotid artery (CCA) via a transcervical approach, while the venous return device 115 accesses a venous return site other than the jugular vein (e.g., a venous return site consisting of the femoral vein (FV)). The venous return device 115 can be inserted into a central vein, such as the femoral vein (FV), via percutaneous puncture in the groin.

[0065] According to another embodiment shown in Figure 1C, the arterial access device 110 accesses the common carotid artery via a femoral approach. The femoral approach allows the arterial access device 110 to access the target common carotid artery (CCA) by ascending the aortic arch (AA) to the CCA, for example, via percutaneous puncture of the femoral artery (FA) in the groin. The venous return device 115 can be connected to the jugular vein (JV) or the femoral vein (FV).

[0066] Figure 1D shows yet another embodiment in which the system provides reflux from the carotid artery to an external receptacle 130 (rather than a venous return site). An arterial access device 110 is connected to the receptacle 130 via a shunt 120, which is connected to a blood flow control assembly 125. The refluxed blood is collected in the receptacle 130. If necessary, the blood can be filtered and then returned to the patient. The pressure in the receptacle 130 may be set to zero pressure (atmospheric pressure) or below, thereby providing a reverse flow of blood from the cerebral blood vessels to the receptacle 130. Optionally, to achieve or enhance reflux from the internal carotid artery, blood flow from the external carotid artery may be blocked by deploying a balloon or other occlusion element, typically in the external carotid artery, directly above the bifurcation with the internal carotid artery. Figure 1D shows the arterial access device 110 arranged in the CCA in a transcervical approach, but it should be noted that an external receptacle 130 can also be used in conjunction with the arterial access device 110 in a transfemoral approach.

[0067] Figure 1E shows yet another embodiment of the backflow system 100. Similar to the previous embodiment, this system includes an arterial access device 110, a shunt 120 with a blood flow control assembly 125, and a venous return device 115. The arterial access device 110 and the venous return device 115 are coupled to the shunt 120 at coupling positions 127a and 127b. In this embodiment, the blood flow control assembly also includes an inline filter, a one-way valve, and a blood flow control actuator, which are housed in a single blood flow control housing.

[0068] With respect to the enlarged view of the carotid artery in Figure 2A, an intervention device such as a stent delivery system 135 or other working catheter can be introduced into the carotid artery via the arterial access device 110, as described in detail below. The stent delivery system 135 can be used to treat plaque P, for example, by deploying a stent into the carotid artery. The arrow RG in Figure 2A represents the direction of regurgitation.

[0069] Figure 2B shows another embodiment in which the arterial access device 110 is used not only to introduce at least one intervention device into the carotid artery but also to form an arterial-to-venous shunt. A separate arterial occlusion device 112 with an occlusion element 129 can be used to occlude the common carotid artery (CCA) at a location proximal to the distal end of the arterial access device 110.

[0070] Figure 2C shows yet another embodiment in which the arterial access device 110 is used not only to occlude the artery using the occlusion element 129 but also to form an arteriovenous shunt. A separate arterial introducer device can be used to introduce at least one intervention device into the carotid artery at a location distal to the arterial access device 110.

[0071] Organizational description Collateral Brain Circulation The Circle of Willis (CW) is the main artery anastomosis of the brain, connecting all major arteries supplying the brain: the two internal carotid arteries (ICAs) and the vertebral basilar system. Blood is delivered from the Circle of Willis to the brain by the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery. This interarterial connection can form collateral circulation through the brain. This provides a safety mechanism in case one or more of the blood vessels supplying blood to the brain are blocked, as blood flow can be formed through alternative routes. Even if any part of the arterial system is blocked (for example, when the ICAs are ligated as described in this specification), the brain can, in most cases, continue to receive adequate blood supply. Blood flow through the Circle of Willis ensures adequate cerebral blood flow through numerous pathways that redistribute blood to the deprived side.

[0072] The collateral potential of the Circle of Willis is thought to depend on the presence and size of its constituent vessels. It should be recognized that considerable anatomical variations between individuals can exist in these vessels, and that many of the included vessels may be diseased. For example, some individuals lack one of the communicating arteries. If occlusion is initiated in such individuals, the collateral circulation is at risk of resulting in ischemic events and potential brain injury. Furthermore, the autoregulatory response to a decrease in perfusion pressure may include dilation of collateral arteries (e.g., communicating arteries) within the Circle of Willis. This compensation mechanism sometimes requires adjustment time before the collateral circulation reaches a level that supports normal function. This autoregulatory response can occur over a period of 15–30 seconds and can only compensate for pressure and blood flow reductions within a certain range. Therefore, transient ischemic attacks (TIAs) may occur during this adjustment period. A very high regurgitation rate over a long period can lead to a situation where the patient's brain does not receive sufficient blood flow, potentially causing unbearable conditions for the patient, such as neurological symptoms or, in some cases, transient ischemic attacks.

[0073] Figure 4 shows the normal cerebral circulation and structure of the Circle of Willis (CW). The aorta (AO) gives rise to the brachiocephalic artery (BCA), which branches into the left common carotid artery (LCCA) and the left subclavian artery (LSCA). The aorta (AO) further gives rise to the right common carotid artery (RCCA) and the right subclavian artery (RSCA). The left and right common carotid arteries (CCAs) give rise to the internal carotid artery (ICA), which branches into the middle cerebral artery (MCA), the posterior communicating artery (PcoA), and the anterior cerebral artery (ACA). The anterior cerebral artery (ACA) supplies blood to the frontal lobe and several parts of the striatum. The middle cerebral artery (MCA) is an aorta with dendritic branches that supply blood to the entire lateral surface of each hemisphere of the brain. The left and right posterior cerebral arteries (PCAs) originate from the basilar artery (BA) and supply blood to the posterior part of the brain (occipital lobe).

[0074] Anteriorly, the Circle of Willis is formed by the anterior cerebral artery (ACA) and the anterior communicating artery (ACoA), which connects the two ACAs. The two posterior communicating arteries (PCoA) connect the Circle of Willis to the two posterior cerebral arteries (PCA), which branch off from the basilar artery (BA) to complete the posterior part of the circle.

[0075] The common carotid artery (CCA) also gives rise to the external carotid artery (ECA), which branches extensively to supply most of the structures of the head except the brain and the contents of the orbit. The ECA also helps supply the structures of the neck and face.

[0076] Carotid artery bifurcation Figure 5 shows a magnified view of the relevant blood vessels in the patient's neck. The common carotid artery (CCA) branches into the internal carotid artery (ICA) and the external carotid artery (ECA) at bifurcation B. The bifurcation is located approximately at the level of the fourth cervical vertebra. Figure 5 shows plaque P formed at bifurcation B.

[0077] As described above, the arterial access device 110 can access the common carotid artery (CCA) via a transcervical approach. Following the transcervical approach, the arterial access device 110 is inserted into the common carotid artery (CCA) at an arterial access site L, which may be, for example, a surgical incision or puncture of the wall of the common carotid artery (CCA). There is typically a distance D of about 5–7 cm between the arterial access site 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 come into contact with the bifurcation B, as this may break up the plaque P and lead to the generation of embolic particles. To minimize the possibility of the arterial access device 110 coming into contact with the bifurcation B, in one embodiment, only about 2–4 cm of the distal region of the arterial access device is inserted into the common carotid artery (CCA) during the procedure.

[0078] The common carotid artery is enclosed on each side by a fascial layer called the carotid sheath. This carotid sheath also encloses the internal jugular vein and the vagus nerve. The sternocleidomastoid muscle is located anterior to the carotid sheath. Percutaneous or surgical transcervical access to the common carotid artery and internal jugular vein is performed from just above the clavicle, through the carotid sheath between the two heads of the sternocleidomastoid muscle, taking care to avoid the vagus nerve.

[0079] At the upper end of the carotid sheath, the common carotid artery divides into the internal and external carotid arteries. The internal carotid artery continues upward without branching until it enters the skull and supplies blood to the retina and brain. The external carotid artery branches to supply blood to the scalp, face, eyes, and other epidermal structures. Several facial and cranial nerves intertwine with the artery both anteriorly and posteriorly. Further neck muscles will also cover the bifurcation. During carotid endarterectomy, these nerve and muscular structures can be dissected and pushed aside to access the carotid bifurcation. In some cases, the carotid bifurcation is closer to the level of the mandible, where access is more challenging and there is less room to separate it from various nerves that need to be avoided. In these cases, incisional endarterectomy may not be the preferred option, as the risk of inadvertent nerve damage may increase.

[0080] Detailed description of the reverse blood flow system As previously mentioned, the regurgitation system 100 includes an arterial access device 110, a venous return device 115, and a shunt 120 that provides a passage for regurgitation from the arterial access device 110 to the venous return device 115. The system also includes a blood flow control assembly 125 that interacts with the shunt 120 to regulate and / or monitor the blood flow regurgitating through the shunt 120. Typical embodiments of the components of the regurgitation system 100 are described here.

[0081] Arterial access devices Figure 6A shows a typical embodiment of an arterial access device 110, which includes a distal sheath 605, a proximal extension 610, a blood flow line 615, an adapter or Y-connector 620, and a hemostatic valve 625. The arterial access device also includes a dilator 645 with a tapered tip 650 and an introducer guidewire 611. Arterial access devices with a dilator and introducer guidewire are used together to increase access to blood vessels. A key feature of arterial access devices is that they can be optimized for transcervical access. For example, the arrangement of the components of the access device can be optimized to limit potential damage to blood vessels by acute-angle insertion, enable non-traumatic and safe sheath insertion, and limit the length of the sheath, sheath dilator, and introducer guidewire inserted into the blood vessel.

[0082] The distal sheath 605 is suitable for introduction through an incision or puncture into the wall of the common carotid artery, either by an open surgical incision or percutaneous puncture established using, for example, the Seldinger technique. The length of the sheath can range from 5 to 15 cm, and is typically 10 to 12 cm. The inner diameter is typically in the range of 7 Fr to 10 Fr (French: 1 Fr = 0.33 mm), and is usually 8 Fr. In particular, when the sheath is introduced via a transcervical approach, above the clavicle but below the carotid bifurcation, it is desirable that the sheath 605 be very flexible while retaining hoop strength to resist kinking and buckling. Thus, the distal sheath 605 may be reinforced from the periphery by a braid, helical ribbon, helical wire, cut tubing, etc., and the inner liner may have a reinforcing structure sandwiched between the outer jacket layer and the inner liner. The inner liner may be a low-friction material such as PTFE. The outer jacket may be one or more materials including Pebax, thermoplastic polyurethane, or nylon. In one embodiment, the reinforcing structure or material and / or the outer jacket material or thickness may vary along the length of the sheath 605 to change the flexibility along the length. In an alternative embodiment, the distal sheath is suitable for introduction, for example, via percutaneous puncture of the femoral artery in the inguinal region, up the aortic arch AA, and into the target common carotid artery CCA.

[0083] As shown in Figure 6B (showing a magnified view of the distal region 630 of the 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 is sized for insertion into the carotid artery, with an inner diameter typically ranging from 2.16 mm (0.085 inches) to 2.92 mm (0.115 inches), while the remaining proximal region of the sheath has larger outer and luminal diameters, with an inner diameter typically ranging from 2.794 mm (0.110 inches) to 3.43 mm (0.135 inches). The larger luminal diameter of the proximal region minimizes the overall blood flow resistance of the sheath. In one embodiment, the length of the reduced-diameter distal portion 630 is approximately 2 cm to 4 cm. The relatively short length of the reduced distal portion 630 allows this portion to be positioned in the common carotid artery (CCA) via a transcervical approach, while reducing the risk of the distal end of the sheath 605 contacting bifurcation B. Furthermore, the reduced distal portion 630 also allows for a reduction in the size of the incised artery into which the sheath 605 is introduced, with minimal impact on the level of blood flow resistance. Moreover, the reduced distal portion is more flexible and therefore can be more conformal to the lumen of the vessel.

[0084] Referring again to Figure 6A, the elongated proximal extension 610 has a lumen that is contiguous with the lumen of the sheath 605. These lumens can be connected by a Y-connector 620, which also connects the lumen of the blood flow line 615 to the sheath. In the assembly system, the blood flow line 615 is connected to the first leg of the regurgitation shunt 120 (Figure 1) to form it. The proximal extension 610 can be long enough to space the hemostatic valve 625 away from the Y-connector 620, which is adjacent to the percutaneous or surgical insertion site. By spacing the hemostatic valve 625 away from the percutaneous insertion site, the physician can introduce the stent delivery system or other working catheter into the proximal extension 610 and sheath 605 while keeping it out of the field of view of the fluoroscopy. In one embodiment, the proximal extension is approximately 16.9 cm from the most distal junction with the sheath 605 (e.g., a hemostatic valve) to the proximal end of the proximal extension. In one embodiment, the proximal extension has an inner diameter of 0.125 inches and an outer diameter of 0.175 inches. In one embodiment, the proximal extension has a wall thickness of 0.025 inches. For example, the inner diameter may range from 0.60 inches to 0.150 inches with a wall thickness of 0.010 inches to 0.050 inches. In another embodiment, for example, the inner diameter may range from 0.150 inches to 0.250 inches with a wall thickness of 0.025 inches to 0.100 inches. The dimensions of the proximal extension may vary. In one embodiment, the proximal extension is approximately 12 to 20 cm in length. In another embodiment, the proximal extension is approximately 20 to 30 cm in length.

[0085] In one embodiment, the distance along the sheath from the hemostatic valve 625 to the distal tip of the sheath 605 is in the range of approximately 25–40 cm. In another embodiment, the distance is in the range of approximately 30–35 cm. With a system configuration that allows for 2.5 cm of sheath introduction into the artery and a 5–10 cm arterial distance from the incised arterial site to the target site, the system allows the distance from the 32–43 cm hemostatic valve 625 (the site of introduction of the intervention device into the access sheath) to the target site to be in the range of approximately 32.5 cm–42.5 cm. This distance is about one-third of the distance required in the prior art.

[0086] A flush line 635 can be connected to the hemostatic valve 625 and may have a plug 640 at its proximal or distal end. The flush line 635 allows for the introduction of saline solution, contrast fluid, etc., during surgery. The flush line 635 will also allow for pressure monitoring during surgery. A dilator 645 with a tapered distal end 650 can be provided to facilitate the introduction of the distal sheath 605 into the common carotid artery. As best seen in Figure 7A, 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 sheath 605. The dilator 645 may have a central lumen to accommodate a guidewire. Typically, the guidewire is first placed in the vessel, and then the dilator / sheath combination moves over the guidewire and is introduced into the vessel.

[0087] As shown in Figure 7A, an optional sheath stopper 705, such as a tube, may be provided, which is coaxially received on the outside of the distal sheath 605. The sheath stopper 705 is designed to act as a sheath stopper to prevent the sheath from being inserted too far into the blood vessel. The sheath stopper 705 is sized and shaped to be positioned on the sheath body 605 so as to cover a portion of the sheath body 605, leaving the distal portion of the sheath body 605 exposed. The tube 705 may have a flared proximal end 710 for engaging with the adapter 620 and a distal end 715. As shown in Figure 7B, the distal end 715 may optionally be angled. The sheath stopper 705 will serve at least two purposes. Firstly, as shown in Figure 7A, the length of the sheath stopper 705 restricts the introduction of the sheath 605 to the exposed distal portion of the sheath 605, thereby limiting the length of the sheath to be inserted to the exposed distal portion of the sheath. In one embodiment, the sheath stopper restricts the exposed distal portion to a range of 2-3 cm. In another embodiment, the sheath stopper restricts the exposed distal portion to 2.5 cm. In other words, the sheath stopper can restrict the insertion of the sheath into the artery to a range of approximately 2-3 cm or 2.5 cm. Secondly, the tube 705 can engage with a pre-deployed puncture closure device placed in the carotid artery wall, allowing the sheath 605 to be withdrawn without removing the closure device, if present. The sheath stopper 705 may be manufactured from a transparent material so that the sheath body beneath it is clearly visible. The sheath stopper 705 may also be made of a flexible material, or it may include an articulating portion or section with increased flexibility to allow the sheath to bend to the appropriate position when inserted into an artery. For example, the distal portion of the sheath stopper may be made of a rigid material, and the proximal portion may be made of a more flexible material.In one embodiment, the harder portion has a durometer hardness of 85A, while the more flexible portion has a durometer hardness of 50A. In one embodiment, the harder distal portion is 1-4 cm of the sheath stopper 705. The sheath stopper 705 may be detachable from the sheath so that, if the user desires to insert a longer sheath, the user can remove the sheath stopper 705, cut it shorter, and reassemble the sheath stopper 705 on the sheath so that a longer insertable sheath protrudes from the sheath stopper 705.

[0088] Figure 7C shows another embodiment of a sheath stopper 705 adjacent to a sheath 605 that houses an expander 645. The sheath stopper 705 in Figure 7C may be deformed from a first shape, such as a straight line, to a second shape different from the first shape, and the sheath stopper 705 remains in the second shape until sufficient external force acts on the sheath stopper to change its shape. The second shape may not be straight, but be curved, or have other contours or irregular shapes. For example, Figure 7C shows a sheath stopper 705 with multiple bends and straight sections. It should be noted that Figure 7C is merely an example and the sheath stopper 705 may be molded to have any amount of bending along the longitudinal axis. Figure 7D shows a sheath stopper 705 positioned on the sheath 605. The sheath stopper 705 is rigider than the sheath 605 so that the sheath 605 takes on a shape or contour that conforms to the contour of the sheath stopper 705.

[0089] The sheath stopper 705 may be shaped according to the insertion angle of the sheath into the artery and the depth of the artery or the patient's body shape. This feature reduces the force on the sheath tip within the vessel wall, especially when the sheath is inserted into the vessel at a steep angle. Even if the angle of incidence to the arterial incision is relatively steep, the sheath stopper may be bent or otherwise deformed to help the entering artery and the sheath be oriented coaxially. The surgeon may shape the sheath stopper before inserting the sheath into the patient. Alternatively, the sheath stopper may be shaped and / or reshaped in situ after the sheath has been inserted into the artery. Figures 7E and 7F show examples of an adaptable sheath stopper in use. Figure 7E shows a linear sheath stopper 705 positioned on the sheath 605. The sheath 605 is fitted with the linear sheath stopper 705 and enters artery A at a relatively steep angle such that the distal tip of the sheath 605 is adjacent to or facing the arterial wall. In Figure 7F, the user bends the sheath stopper 705 to adjust the angle of incidence of the sheath 605 so that the long axis of the sheath 605 is more parallel to the axis of artery A. In this configuration, the sheath stopper 705 is formed by the user in a shape that assists the sheath 605 in oriented away from the opposite wall of artery A, and in a direction that is more coaxial with the axis of artery A compared to the shape in Figure 7E.

[0090] In one embodiment, the sheath stopper 705 is made of an adaptable material or includes an adaptable composite component placed on or inside the sheath stopper. In another embodiment, the sheath stopper is configured to be joined using actuators such as concentric tubes or pull wires. The walls of the sheath stopper may be reinforced with ductile wires or ribbons to help maintain its shape against external forces, for example, when the sheath stopper faces a bend in an artery or passageway. Alternatively, the sheath stopper may be constructed of a uniform, adaptable tubular material including metal and polymer. The body of the sheath stopper may also be at least partially constructed of a reinforced braid or coil capable of retaining its deformed shape.

[0091] Another embodiment of a sheath stopper is designed to facilitate adjustment of the position of the sheath stopper (relative to the sheath) even after the sheath has been placed in the blood vessel. One embodiment of a sheath stopper includes a tube having a slit along its entire length or most of its length so that the sheath stopper can be removed from the sheath body, moved forward or backward as desired, and then repositioned along the length of the sheath body. The tube may have a grip or feature at its proximal end to allow it to be grasped and removed more easily.

[0092] In another embodiment, the sheath stopper is a very short tube (such as a band) or a ring located on the distal portion of the sheath body. The sheath stopper may be easily grasped with forceps and may include features that allow it to be pulled backward or forward to a desired new position, for example, to properly set the length of sheath insertion during a procedure. The sheath stopper may be secured to the sheath body either by friction from the tubular material or through a clamp that can be opened and closed relative to the sheath body. The clamp may be a spring-loaded clamp, usually fixed on the sheath body. To move the sheath stopper, the user may open the clamp with their fingers or an instrument, adjust the position of the clamp, and then release the clamp. The clamp should be designed so as not to interfere with the sheath body.

[0093] In another embodiment, the sheath stopper includes a feature that allows the sheath stopper and sheath to be sutured to the patient's tissue, which improves sheath retention and reduces the risk of sheath dislodgement. This feature may also be a suture eyelet that is present within or formed within the sheath stopper tube.

[0094] In another embodiment, as shown in Figure 9A, the sheath stopper 705 includes a distal flange 710, which is sized and shaped to distribute the force of the sheath stopper over a larger area on the vessel wall, thereby reducing the risk of accidental insertion of the sheath stopper into the vessel through a damaged or incised artery. The flange 710 may be circular or other non-traumatic shape, large enough to distribute the force of the sheath stopper over a larger area on the vessel wall. In one embodiment, the flange is expandable or mechanically expandable. For example, the arterial sheath and sheath stopper may be inserted into the surgical site through a small puncture in the skin and then expanded before insertion of the sheath into the artery.

[0095] The sheath stopper may include one or more cutouts or indentations 720 along its length, forming a staggered configuration such that the indentations increase the flexibility of the sheath stopper while maintaining axial strength that allows the sheath stopper to exert a forward force against the arterial wall. Indentations may also be used to facilitate securing the sheath to the patient via sutures and to reduce sheath dislodgement. The sheath stopper may also include a connector element 730 on its proximal end, corresponding to the features of the arterial sheath, so that the sheath stopper can be fixed to or detached from the arterial sheath. For example, the connector element is generally a hub with an L-shaped slot 740, which corresponds to a pin 750 on the hub for making a mount-style bayonet connection. In this configuration, the sheath stopper can be securely connected to the hub, reducing the likelihood of the sheath stopper being inadvertently removed from the hub unless it is detached from the hub.

[0096] The distal sheath 605 can be configured to establish a change in curve from the usual anterior-posterior approach over the common carotid artery to the axial direction of the usual lumen within the common carotid artery. Arterial access through the wall of the common carotid artery, whether from a direct surgical incision or percutaneous access, may typically require a larger access angle than other arterial access sites. This is because the insertion site in the common carotid artery is much closer to the treatment site (i.e., the carotid bifurcation) than from other access points. A larger access angle is necessary to increase the distance from the insertion site to the treatment site, which allows for sheath insertion at an appropriate distance without the distal tip of the sheath reaching the carotid bifurcation. For example, the insertion angle of the sheath via transcervical access is typically 30-45° or even larger, while in access to the femoral artery, the insertion angle of the sheath may be 15-20°. Therefore, the sheath must bend more than typical, with an introducer sheath, without twisting and without creating excessive force on the contralateral arterial wall. In addition, the tip of the sheath should not be adjacent to or in contact with the arterial wall after insertion, in a manner that restricts blood flow to the sheath. The insertion angle of the sheath is defined as the angle between the axis of the arterial lumen and the long axis of the sheath.

[0097] The sheath body 605 may be formed in various ways to allow for the greater bending required by the angle of access. For example, the sheath and / or expander may have a combined flexible bending stiffness that is lower than that of a typical introducer sheath. In one embodiment, the sheath / expander combination (i.e., a sheath with an expander positioned inside the sheath) has a bending stiffness of approximately 80 and 100 N-m 2 x 10 -6 The flexible composite has a stiffness (E*I) in the range of E, where E is the modulus of elasticity and I is the area moment of inertia of the device. The sheath alone has a stiffness of approximately 30 to 40 N-m 2 x 10 -6It has a bending stiffness in the range of [range], and the expander alone has a bending stiffness of approximately 40 to 60 N-m 2 x 10 -6 It has a bending stiffness in the range of 150 to 250 N-m. The bending stiffness of a typical sheath / expander is 150 to 250 N-m. 2 x 10 -6 This is within the range. Greater flexibility can be achieved through the selection of reinforcing materials or designs. For example, the sheath may have reinforcement of a stainless steel ribbon coil with dimensions of 0.002” to 0.003” thickness and 0.005” to 0.015” width and an outer coating with a durometer hardness of 40 to 55D. In one embodiment, the coil ribbon is 0.003” x 0.010” and the outer coating has a durometer hardness of 45D. In one embodiment, the sheath 605 can be pre-shaped to have a curved or angular section at a predetermined distance (typically 0.5 to 1 cm) from the tip. The pre-shaped curved or angular section may provide a bend (turn) typically in the range of 5° to 90°, preferably in the range of 10° to 30°. In the initial stages of insertion, the sheath 605 will be straightened by an obturator, such as a dilator 645, or other straight or shaped instruments placed in its lumen. After the sheath 605 has been at least partially introduced through percutaneous or other arterial wall penetration, the obturator is withdrawn to allow the sheath 605 to regain its pre-shaped form within the arterial lumen. To retain the shape of the curved or angular portion of the sheath body after being straightened during insertion, the sheath may be heat-set in the shape of the curved or angular portion during manufacturing. Alternatively, a reinforcing structure may be made of nitinol and heat-formed into the shape of the curved or angular portion during manufacturing. Alternatively, an additional spring element may be added to the sheath body, for example, a spring of spring steel or nitinol, in the precise shape, to the reinforcement layer of the sheath.

[0098] Other sheath structures include having a deflection mechanism that allows the sheath to be placed, and the catheter can deflect to a desired deployment angle in situ. In yet another structure, the catheter has a non-rigid configuration when placed within the lumen of the common carotid artery. After placement within the lumen, a pull wire or other stiffening mechanism can be deployed to shape or stiffen the sheath into a desired structure. One specific example of such a mechanism is commonly known as a "shape-lock" mechanism, which is well described in medical and patent literature.

[0099] Another sheath structure includes a curved dilator that is inserted into a straight and flexible sheath, and the dilator and the sheath curve during insertion. The sheath is sufficiently flexible to conform to tissue after the dilator is removed.

[0100] Another sheath embodiment is a sheath that includes one or more flexible distal portions that can be bent to a large angle at the corner structure during insertion without twisting the sheath and without generating excessive force on the opposite arterial wall. In one embodiment, the most distal portion of the sheath body 605 is more flexible than the remainder of the sheath body. For example, the bending stiffness of the most distal portion is from one-half to one-tenth of the bending stiffness of the remainder of the sheath body 605. In certain embodiments, the bending stiffness of the most distal portion is from 30 to 300 N-mm 2 and the bending stiffness of the remaining portion of the sheath body 605 is from 500 to 1500 N-mm 2In a sheath configured for a CCA access site, the most distal flexible portion includes a significant portion of the sheath body 222 that can be expressed as a ratio. In one embodiment, the ratio of the length of the most distal flexible portion to the total length of the sheath body 222 is at least one-tenth and at most one-half of the total length of the sheath body 222. This modification in flexibility can be achieved in various ways. For example, the durometer hardness and / or material of the outer covering in different portions may be changed. Alternatively, the reinforcing structure or reinforcing material may be changed along the length of the sheath body. In one embodiment, the most distal flexible portion is in the range of 1 cm to 3 cm. In one embodiment with one or more flexible portions, the less flexible portion (relative to the most distal portion) may be 1 cm to 2 cm from the proximal portion of the most distal portion. In one embodiment, the distal flexible portion is about 30 to 50 N-m 2 x 10 -6 It has a bending stiffness in the range of approximately 50 to 100 N-m, with the less flexible parts having a bending stiffness of about 50 to 100 N-m. 2 x 10 -6It has a bending stiffness in the range of . In another embodiment, the more flexible portion is located at 0.5 to 1.5 cm of a length of 1 to 2 cm, and the sheath enters the artery at a certain angle, but creates an articulation portion that allows the distal portion of the sheath to become more easily parallel to the axis of the vessel. These configurations, including various flexible portions, may be manufactured in several ways. For example, the less flexible reinforced portions may vary, such that the proximal portion has a stiffer reinforcement and the distal portion or articulation portion has a more flexible reinforcement. In one embodiment, the outermost covering material of the sheath has a durometer hardness of 45D to 70D in the proximal portion and 80A to 25D in the most distal portion. In one embodiment, the flexibility of the sheath varies continuously along the length of the sheath body. Figure 7G shows such a sheath for insertion into an artery, having a flexible distal portion that allows the sheath body to bend, and its distal tip to become roughly in line with the lumen of the vessel. In one embodiment, the distal portion is made to include a more flexible reinforcing structure by either varying the pitch of the coil or braid, or by incorporating hypotube cut with different cutting patterns. Alternatively, the distal portion has a different reinforcing structure from the proximal portion.

[0101] In one embodiment, the tapered tip of the distal sheath is manufactured from a material harder than the body of the distal sheath. The purpose of this is to facilitate sheath insertion by allowing for a very smooth tapering on the sheath and to reduce changes in sheath tip distortion or elliptical deformation during and after sheath insertion into the blood vessel. In one embodiment, the material of the distal tapered tip is manufactured from a harder durometer hardness material, such as a material with a Shore hardness of 60-72D. In another embodiment, the distal tip is manufactured from a separate material, such as HDPE, stainless steel, or another suitable polymer or metal. In an additional embodiment, the distal tip is manufactured from a radiopaque material, either as an addition to a polymer material such as tungsten or barium sulfate, or as an inherent property of the material (as in the case of most metallic materials).

[0102] In another embodiment, the dilator 645 may also have varying degrees of stiffness. For example, the tapered tip 650 of the dilator may be made of a more flexible material than the proximal portion of the dilator, which minimizes the risk of vascular damage when inserting the sheath and dilator into the artery. In one embodiment, the flexible distal portion may have a stiffness of about 45 to 55 N-m 2 x 10 -6 It has a bending stiffness in the range of 60 and 90 N-m, with the less flexible proximal portion being approximately 60 and 90 N-m. 2 x 10 -6 It has a bending stiffness in the range of [range]. The tapered shape of the dilator may be optimized for transcervical access. For example, to limit the amount of sheath and dilator that enters the artery, the tapered length and the amount of dilator extending beyond the sheath should be shorter than that of a typical introducer sheath. For example, the tapered length may be 1 to 1.5 cm and may extend 1.5 to 2 cm from the end of the sheath body. In one embodiment, the dilator includes a radiopaque marker at the distal tip so that the position of the tip is easily visible under fluoroscopy.

[0103] In another embodiment, the introducer guidewire is optimally configured for transcervical access. Typically, when inserting the introducer sheath into a blood vessel, the introducer guidewire is inserted first into the vessel. This may be done using either micropuncture techniques or the modified Seldinger method. For example, in the femoral artery, where the introducer guidewire may be inserted, there is usually a long vessel in the direction from which the sheath is inserted. In this case, the user may introduce the guidewire 10 to 15 cm or more into the vessel before inserting the sheath. To avoid damaging the vessel when introduced into the artery, the guidewire is designed to have a flexible distal portion. The flexible portion of the introducer sheath guidewire is typically 5 to 6 cm long and gradually transitions to a stiffer portion. Inserting 10 to 15 cm of the guidewire means that the stiff portion of the guidewire is positioned in the puncture area, allowing for stable assistance in the subsequent insertion of the sheath and dilator into the blood vessel. However, in the case of transcervical sheath insertion into the common carotid artery, there are limitations on the amount of guidewire that can be inserted into the carotid artery. In cases of carotid artery disease at the bifurcation or internal carotid artery, it is desirable to minimize the risk of embolism by inserting the wire into the external carotid artery, which means inserting only about 5 to 7 cm of guidewire, or it is desirable to stop the wire before reaching the branch, which means inserting only 3 to 5 cm of guidewire. Therefore, transcervical sheath guidewires may have a shorter transition to a more flexible distal portion of 3 to 4 cm and / or a more rigid portion. Alternatively, transcervical sheath guidewires may have a non-traumatic tip portion but a very distal and short transition to a more rigid portion. For example, the flexible tip portion may be 1.5 to 2.5 cm, followed by a transition portion of 3 to 5 cm in length, and then a rigid proximal segment with a rigid proximal portion containing the rest of the wire.

[0104] In addition to the above configuration, introducer guidewires, micropuncture catheters, or micropuncture catheter guidewires may include features to prevent inadvertent advancement of these devices into the affected portion of the carotid artery. For example, stopper features may be placed on the introducer guidewire, micropuncture catheter, and / or micropuncture guidewire to limit the insertable length of these devices. For example, the stopper feature may be a short section of tubing that can be slidably positioned on the device and, once positioned, remains in place on the device by friction. For example, the stopper feature may be made of a soft polymer material such as silicone rubber, polyurethane, or other thermoplastic elastomers. The stopper feature may have an inner diameter the same size as or slightly smaller than the diameter of the device. Alternatively, the stopper feature may be configured to be fixed on the device such that the user must press firmly on the stopper feature or release it to detach or re-fix the stopper feature from the device in order to release the device and reposition the device. The characteristics of the stopper may be positioned to be optimally inserted into the blood vessel based on the location of the puncture site, the distance of the bifurcation to the puncture site, and the amount of disease at the carotid artery bifurcation.

[0105] The sheath guidewire may have guidewire markings to help the user determine the position of the wire tip relative to the dilator. For example, there may be a mark at the proximal end of the wire corresponding to when the wire tip is just present at the tip of the microaccess cannula. This mark provides quick feedback on wire position and helps limit the amount of wire the user inserts. In another embodiment, the wire may include additional marks, indicated by a set distance (e.g., 5 cm), to inform the user when the wire is present in the cannula. Alternatively, the introducer guidewire, micropuncture catheter, and / or micropuncture guidewire may consist of, or have a portion of, a material that can be marked with a marking pen, where this mark is easily visible within the catheterization lab or operating room (OR) environment. In this embodiment, the user pre-marks the components based on anatomical information as described above and uses these marks to determine the maximum insertion amount in each component. For example, the guidewire may have a white coating around the marked portion.

[0106] In one embodiment, the sheath has a built-in puncture capability and an atraumatic tip similar to that of a guidewire. This eliminates the need for needle and wire changes currently used in arterial access using micropuncture technology, thus saving time, reducing blood loss, and requiring less surgical skill.

[0107] In another embodiment, the sheath dilator is configured to be inserted onto a 0.018” guidewire for transcervical access. Standard sheath insertion using a micropuncture kit requires the initial insertion of a 0.018” guidewire through a 22Ga needle, followed by replacement with a 0.035” or 0.038” guidewire using a micropuncture catheter, and finally insertion of the sheath and dilator onto the 0.035” or 0.038” guidewire. Since there are sheaths that can be inserted over a .018” guidewire, wire replacement is unnecessary. These sheaths (designed for insertion into the radial artery and therefore commonly called “transradial” sheaths) typically have a longer tapered dilator, allowing for a suitable increase in diameter from the .018” wire to the sheath body. Unfortunately, in transcervical access, the length of sheath and dilator insertion is limited, and therefore these existing sheaths are not suitable. Another disadvantage is that the .018” guidewire cannot provide the necessary assistance to insert the sheath into the carotid artery at a sharper angle. In embodiments disclosed herein, the transcervical sheath system includes a sheath body, a sheath dilator, and an internal tube with a tapered distal end that slides slidably into the sheath dilator and can accommodate a .018” guidewire.

[0108] To use this embodiment of the sheath system, a .018” guidewire is first inserted into the blood vessel through a 22Ga needle. The coaxially mounted sheath system is then inserted onto the .018” wire. The inner tube is first advanced onto the .018” wire, which essentially converts the .018” wire to something equivalent to a .035” or .038” guidewire, both in terms of outer diameter and mechanical assistance. It is then secured to the .018” wire at its proximal end. The sheath and dilator are then advanced into the blood vessel on the .018” wire and inner tube. This configuration eliminates the need for a longer dilator tapering, similar to current transradial artery sheaths, and eliminates the wire change procedure, with guidewire assistance similar to standard introducer sheaths. As described above, this configuration of the sheath system may also include a stopper feature, which prevents the .018” guidewire and / or internal tube from inadvertently advancing too far during sheath insertion. Once the sheath is inserted, the dilator, internal tube, and .018” guidewire are removed.

[0109] Figure 8A shows another embodiment of the arterial access device 110. This embodiment is substantially similar to the embodiment shown in Figure 6A, except that the distal sheath 605 includes an occlusion element 129 for occluding blood flow (e.g., through 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 communicating with the occlusion element 129. The occlusion element 129 may be an inflatable balloon, but may also be an inflatable cuff, an outwardly flared conical or other circumferential element that engages with the inner wall of the common carotid artery and blocks blood flow passing through it, a membrane-covered braid, a slotted tube that expands radially when compressed axially, or a similar structure that can be deployed by mechanical means, etc. In the case of balloon occlusion, the balloon may be compliant, non-compliant, elastomeric, reinforced, or have a variety of other characteristics. In one embodiment, the balloon is an elastic balloon that, before inflation, is tightly fitted to the outside of the distal end of the sheath. When inflated, the elastic balloon can expand and conform to the inner wall of the common carotid artery. In one embodiment, the elastic balloon can expand to at least twice its diameter compared to its unexpanded form, often to at least three times its diameter compared to its unexpanded form, and more preferably to at least four times its diameter, or more, compared to its unexpanded form.

[0110] As shown in Figure 8B, the distal sheath 605 with the occlusion element 129 may have a stepped or other configuration having 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 a larger outer and inner diameter, with the inner diameter typically ranging from 2.794 mm (0.110 inches) to 3.43 mm (0.135 inches). The larger inner diameter of the proximal region minimizes the overall blood flow resistance of the sheath. In one embodiment, the length of the reduced-diameter distal portion 630 is approximately 2 cm to 4 cm. The relatively short length of the reduced-diameter distal portion 630 allows this portion to be positioned in the common carotid artery (CCA) via a transcervical approach, while reducing the risk of the distal end of the sheath 605 contacting bifurcation B.

[0111] Figure 2B shows an alternative embodiment in which the occlusion element 129 can be introduced into the carotid artery on a separate second sheath 112 from the distal sheath 605 of the arterial access device 110. The second or “proximal” sheath 112 would be suitable for insertion into the common carotid artery in a proximal or “inferior” direction away from the cerebral blood vessels. As schematically described above, the second proximal sheath may contain an inflatable balloon 129 or other occlusion element. The distal sheath 605 of the arterial access device 110 can then be placed in the common carotid artery distal to the second proximal sheath and typically oriented distally toward the cerebral blood vessels. Using separate occlusion and access sheaths can reduce the size of the artery incised for introduction of the access sheath.

[0112] Figure 2C shows yet another embodiment of the two arterial sheath systems, in which the intervention device is introduced by an introduction sheath 114 separate from the distal sheath 605 of the arterial device 110. The second or “distal” sheath 114 would be suitable for insertion into the common carotid artery distal to the arterial access device 110. As with the previous embodiment, the size of each incised artery can be reduced by using two separate access sheaths.

[0113] As can be seen in transcervical access procedures, when the insertion of a sheath into an artery is at an acute angle and / or the length of the sheath to be inserted is short, the distal tip of the sheath is more likely to be positioned in partial or complete contact with the vessel wall, thereby restricting blood flow to the sheath. In one embodiment, the sheath is designed so that its tip is centrally positioned within the lumen of the vessel. One such embodiment includes a balloon, such as the occlusion element 129 described above. In another embodiment, the balloon does not occlude blood flow and, like an inflatable bumper, the tip of the sheath may be centrally positioned away from the vessel wall. In another embodiment, an inflatable feature is located at the tip of the sheath and mechanically inflates when the sheath is placed in place. Embodiments of mechanically inflatable features include a braided or helical structure or a longitudinal support that expands radially when compressed.

[0114] In one embodiment, occlusion of the vessel proximal to the distal tip of the sheath may be performed from the outside of the vessel, such as with a Rummel tourniquet or a vascular loop proximal to the sheath insertion site. In an alternative embodiment, the occlusion device may be fitted to the outside of the vessel around the sheath tip, such as an elastic loop, an inflatable cuff, or a mechanical clamp that can constrict the vessel and the distal tip of the sheath. In a system of blood flow regurgitation, this method of vascular occlusion minimizes the area where blood flow is stagnant, thereby reducing the risk of thrombus formation, and ensures that the sheath tip is axially aligned with the vessel and not partially or completely blocked by the vessel wall.

[0115] In one embodiment, the distal portion of the sheath body may include a side hole so that blood flow to the sheath is maintained even if the tip of the sheath is partially or completely blocked by the arterial wall.

[0116] Another arterial access device is shown in Figures 9A-9D. This configuration has a different style of connection to the blood flow shunt than the previously described variant. Figure 9A shows the components of the arterial access device 110, including an arterial access sheath 605, a sheath dilator 645, a sheath stopper 705, and a sheath guidewire 111. Figure 9B shows the arterial access device 110 as assembled for insertion onto the sheath guidewire 611 into the carotid artery. After insertion of the sheath into the artery and during the procedure, the sheath guidewire 611 and the sheath dilator 705 are removed. In this configuration, the sheath has a sheath body 605, a proximal extension 610, and a hemostatic valve 625 with a flush line 635 and a plug 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 605 is the part that is sized to be inserted into the carotid artery, and is actually inserted into the artery during use.

[0117] Instead of a Y-connector with a blood flow line connection terminating within the valve, the sheath has 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 that can be operated to open and close a fluid connection to a connector or hub 680 to which a blood flow line, such as a shunt, can be detachably connected. The valve 670 is positioned immediately adjacent to the internal lumen of the adapter 660, which communicates with the internal lumen of the sheath body 605. Figures 9C and 9D show cross-sectional details of the Y-adapter 660 with the valve 670 and hub 680. Figure 9C shows the valve closed to the connector. This is the valve configuration during adjustment of the arterial sheath. The valve is configured so as not to trap air during adjustment of the sheath. Figure 9D shows the valve open to the connector. This configuration is used when a blood flow shunt 120 is connected to the hub 680, allowing blood flow from the arterial sheath to the shunt. This configuration eliminates the need to adjust both the flush line and the blood flow line, instead allowing adjustment at a single flush line 635 and stopper 640. This single-point adjustment is identical to the adjustment of conventional introducer sheaths without a shunt line connection, making it more familiar and convenient for the user. In addition, the absence of a blood flow line on the sheath makes handling the arterial sheath easier during adjustment and insertion into the artery.

[0118] Again, with respect to Figure 9A, the sheath may also include a second, more distal connector 690, which is separated from the Y-adapter 660 by a section of tube 665. The purpose of this second connector and tube 665 is to allow the valve 670 to be positioned further proximal to the distal end of the sheath while still limiting the length of the insertable portion of the sheath 605, and thus allowing for a reduction in the level of the user's exposure to the radiation source when the blood flow shunt is connected to the arterial sheath during the procedure. In one embodiment, the distal connector 690 includes a small opening for sutures to help secure the sheath to the patient after placement.

[0119] Vein return device Referring next to Figure 10, the venous return device 115 may include a distal sheath 910 and a blood flow line 915, which, during use of the system, are connected to a shunt 120 to form a leg of the shunt 120. The distal sheath 910 is suitable for introduction into a venous return site (such as a jugular or femoral vein) through an incision or puncture. The distal sheath 910 and blood flow line 915 can be permanently attached or attached using conventional Luer fittings, as shown in Figure 10A. Optionally, the sheath 910 can be connected to the blood flow line 915 by a Y-connector 1005, as shown in Figure 10B. 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 vein or other vein. Similar to the arterial access dilator 645, the venous dilator 1015 includes a central lumen on the guidewire, thereby allowing the combination of the venous sheath and dilator to be placed on the guidewire 611. Optionally, the venous sheath 910 may include a flush line 1020 with a plug 1025 at its proximal or distal end.

[0120] Alternative configurations are shown in Figures 10C and 10D. Figure 10C shows the components of a venous return device 115, including a venous return sheath 910, a sheath dilator 1015, and a sheath guidewire 611. Figure 10D shows the venous return device 115 as assembled for insertion onto 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 blood flow line 915. A plug 1025 at the end of the blood flow allows the venous sheath to be flushed through the blood flow line before use. This configuration allows the sheath to be adjusted from a single point, similar to a conventional introducer sheath. The connection of the blood flow shunt 120 is made with a connector 1030 on the plug 1025.

[0121] To reduce the overall system blood flow resistance, each of the arterial access blood flow line 615 (Figure 6A) and venous return blood flow line 915, as well as the Y connectors 620 (Figure 6A) and 1005, can have a relatively large internal diameter for blood flow, typically ranging from 2.54 mm (0.100 inches) to 5.08 mm (0.200 inches), and a relatively short length, typically ranging from 10 cm to 20 cm. Low system blood flow resistance is desirable because it allows for maximum blood flow during a period of the procedure when the risk of embolism is highest. As will be described in detail below, low system blood flow resistance also allows for the use of variable blood flow resistance to control blood flow in the system. The dimensions of the venous return sheath 910 are approximately the same as those of the arterial access sheath 605 described above. No extension for the hemostatic valve 1010 is required within the venous return sheath.

[0122] Retrograde Shunt The shunt 120 can be formed from a single tube or multiple connecting tubes that provide fluid communication between the arterial access catheter 110 and the venous return catheter 115, and provide a pathway for blood flow to flow back between them. As shown in Figure 1A, the shunt 120 connects at one end to the blood flow line 615 of the arterial access device 110 (via connector 127a) and at the other end to the blood flow line 915 of the venous return catheter 115 (via connector 127b).

[0123] In one embodiment, the shunt 120 may be formed by at least one tube leading to a blood flow control assembly 125. The shunt 120 may be any structure that provides a fluid pathway for blood flow. The shunt 120 may have a single lumen or multiple lumen. The shunt 120 may be detachably attached to the blood flow control assembly 125, the arterial access device 110 and / or the venous return device 115. Prior to use, the user can select a shunt 120 of the optimal length for use at the arterial access site and the venous return site. In one embodiment, the shunt 120 may include one or more extension tubes that can be used to change the length of the shunt 120. The extension tubes may be modularly attached to the shunt 120 to achieve the desired length. The modular configuration of the shunt 120 allows the user to extend the shunt 120 depending on the venous return site as needed. For example, in some patients, the internal jugular vein (IJV) is small and / or twisted. Because of its proximity to other tissue structures, the risk of complications at this location may be higher than at other locations. Furthermore, a hematoma in the neck may cause airway obstruction and / or cerebrovascular complications. Therefore, for such patients, it would be preferable to place the venous return site in a location other than the internal jugular vein (IJV), such as the femoral vein. A femoral vein return site may be achieved percutaneously with a lower risk of serious complications and also provides alternative venous access to a central vein if the internal jugular vein (IJV) is unavailable. In addition, a femoral vein return modifies the layout of the regurgitant shunt so that the shunt control is positioned closer to the "working area" of the intervention where the device is introduced and the contrast injection port is located.

[0124] In one embodiment, the shunt 120 has an inner diameter of 4.76 mm (3 / 16 inch) and a length of 40-70 cm. Yes. As mentioned above, the length of the shunt can be adjusted. In one embodiment, the connector between the shunt and the arterial and / or venous access device is configured to minimize blood flow resistance. In one embodiment, as shown in Figures 1A-1D, an arterial access sheath 110, a regurgitation shunt 120, and a venous return sheath 115 are combined to create an arteriovenous AV shunt with low blood flow resistance. As mentioned above, the connections and blood flow lines of all these devices are optimized to minimize or reduce blood flow resistance. In one embodiment, the AV shunt has a blood flow resistance that allows for blood flow of up to 300 mL / min when there is no device in the arterial sheath 110 and the AV shunt is connected to a fluid source with blood viscosity and a static pressure of 60 mmHg of water. The actual shunt resistance may vary depending on the presence or absence of a check valve 1115 or filter 1145 (as shown in Figure 11) or the length of the shunt, and blood flow of 150 to 300 mL / min may be possible.

[0125] When a device such as a stent delivery catheter is present within the arterial sheath, there is a portion of the arterial sheath that increases blood flow resistance, which in turn increases the overall blood flow resistance of the AV shunt. This increase in blood flow resistance has a corresponding decrease in blood flow. In one embodiment, a Y-arm 620, as shown in Figure 6A, connects the arterial sheath body 605 to a blood flow line 615 located a short distance from the hemostatic valve 625 that introduces the catheter into the sheath. This distance is determined 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 605. The actual restriction of blood flow depends on the length and inner diameter of the sheath body 605 as well as the outer diameter of the catheter. As mentioned above, the sheath length may range from 5 to 15 cm, but is usually 10 to 12 cm, and the inner diameter is typically 7 Fr to 10 Fr (1 Fr = 0.33 mm), but is usually 8 Fr. Stent delivery catheters may range from 3.7 Fr to 5.0 Fr or 6.0 Fr, depending on the stent and manufacturer size. As shown in Figure 6B, this limitation can be further reduced if the sheath body is designed to increase the inner diameter of the portion other than the intravascular portion (stepped sheath body). Since blood flow restriction is proportional to the fourth power of the lumen distance, small increases in lumen or annular area result in a large reduction in blood flow restriction.

[0126] The actual blood flow through the AV shunt during use further depends on the patient's brain blood pressure and blood flow resistance.

[0127] Blood flow control assembly - regulation and monitoring of regurgitation The blood flow control assembly 125 interacts with the regurgitation shunt 120 to regulate and / or monitor the regurgitation velocity from the common carotid artery to venous return sites such as the femoral vein or internal jugular vein, or to the external receptacle 130. In this regard, the user can achieve a higher maximum blood flow velocity than existing systems with the blood flow control assembly 125, and can also selectively regulate, set, or adjust the regurgitation velocity. The regurgitation velocity can be regulated using various mechanisms, as fully described below. As described below, the user can configure the regurgitation velocity with the blood flow control assembly 125 in a manner suitable for various procedures.

[0128] Generally, the ability to control continuous regurgitation velocity allows physicians to adapt protocols for individual patients and surgical stages. Regurgitation velocity is typically controlled across a low-to-high range. High velocity is at least twice as fast as low velocity, typically at least three times faster than low velocity, and often at least five times or more faster than low velocity. In some embodiments, high velocity is at least three times faster than low velocity, and in other embodiments, high velocity is at least six times faster than low velocity. While it is generally desirable to increase regurgitation velocity to maximize embolic extraction from the carotid artery, patients' ability to tolerate regurgitation varies. Thus, having systems and protocols that allow for easy adjustment of regurgitation velocity allows the treating physician to determine and adjust the regurgitation velocity accordingly when the velocity exceeds a level that the patient can tolerate. For patients who cannot tolerate continuous high regurgitation velocity, the physician can choose to activate high-velocity blood flow only for a short period of time when the risk of embolic debris is highest and the procedure is dangerous. At short intervals, such as 15 seconds to 1 minute, the patient's tolerance limit is usually not a factor.

[0129] In certain embodiments, the continuous regurgitating blood flow velocity can be controlled at a baseline velocity in the range of 10 ml / min to 200 ml / min, typically in the range of 20 ml / min to 100 ml / min. These velocity ranges are tolerable for the majority of patients. While the blood flow velocity is maintained at the baseline for most of the procedure, it can be briefly increased above baseline to enhance the ability to capture such emboli when the risk of embolic ejection increases. For example, the regurgitating blood flow velocity can be increased above baseline when the stent catheter is introduced, when the stent is deployed, before and after stent expansion, and during removal of the common carotid artery occlusion.

[0130] The blood flow velocity control system can alternate between relatively low and relatively high blood flow velocities to "flush" the carotid arteries within the carotid bifurcation region before restoring antegrade blood flow. Such repetitions can establish a high blood flow velocity that is approximately 2 to 6 times faster than the low blood flow velocity, typically about 3 times faster. The repetition cycle can typically range in length from 0.5 to 10 seconds, usually from 2 to 5 seconds, and the total duration of the repetitions can range from 5 to 60 seconds, usually from 10 to 30 seconds.

[0131] Figure 11 shows an embodiment of system 100, including a layout diagram of the blood flow control assembly 125, which is positioned along the shunt 120 such that the regurgitating blood flow passes through or is connected to at least a portion of the blood flow control assembly 125. The blood flow control assembly 125 may include various controllable mechanisms for regulating and / or monitoring the regurgitation. These mechanisms may include various means for regurgitation control, including one or more pumps 1110, valves 1115, syringes 1120, and / or variable resistance components 1125. The blood flow control assembly 125 can be manually controlled by the user and / or automatically controlled via a controller 1130 to alter the blood flow through the shunt 120. For example, the velocity of the regurgitating blood flow through the shunt 120 can be controlled by changing the blood flow resistance. The controller 1130 (described in more detail below) can be integrated into the blood flow control assembly 125, or it can be a separate component connected to the components of the blood flow control assembly 125.

[0132] Furthermore, the blood flow control assembly 125 may include one or more flow sensors 1135 and / or anatomical data sensors 1140 (described in detail below) to detect one or more conditions of backflow. A filter 1145 may be positioned along the shunt 120 to remove embolus before blood returns to the venous return site. Positioning the filter 1145 upstream of the controller 1130 allows the filter 1145 to prevent embolus from entering the controller 1145 and clogging the variable flow resistance component 1125. It should be recognized that the various components of the blood flow control assembly 125 (including the pump 1110, valve 1115, syringe 1120, variable resistance component 1125, sensors 1135 / 1140, and filter 1145) can be positioned at various locations along the shunt 120 and at various upstream or downstream positions relative to each other. The components of the blood flow control assembly 125 are not limited to the locations shown in Figure 11. Furthermore, the blood flow control assembly 125 does not necessarily include all components, but rather may include various sub-combinations of components. For example, a syringe may be optionally used within the blood flow control assembly 125 for the purpose of regulating blood flow, or it may be used outside the assembly for purposes other than blood flow regulation, such as introducing a fluid such as a radiographic contrast agent into an artery in an anterograde direction via the shunt 120.

[0133] Both the variable resistance component 1125 and the pump 1110 can be connected to the shunt 120 to control the velocity of the regurgitating blood flow. The variable resistance component 1125 controls the blood flow resistance while the pump 1110 delivers blood through the shunt 120 in a positive displacement manner. In this way, the regurgitation can be driven by operating the pump rather than relying on the perfusion stump pressures of the ECA and ICA and the back pressure of the veins. The pump 1110 can be any type of pump, including a peristaltic tube pump or a positive displacement pump. The pump 1110 can be started or stopped (manually or automatically via the controller 1130) to selectively achieve blood movement through the shunt 120 and to control the velocity of the blood flow through the shunt 120. Blood movement through the shunt 120 can also be achieved by other means, including the use of a suction syringe 1120, or by using an insulation source such as a vacutainer, vaculock syringe, or wall aspiration. The pump 1110 can be connected to the controller 1130.

[0134] One or more blood flow control valves 1115 can be positioned along the shunt pathway. The valves can be moved manually or automatically (via the controller 1130). The blood flow control valves 1115 can be, for example, one-way valves to prevent anterograde blood flow in the shunt 120, check valves, or high-pressure valves to close the shunt 120 during, for example, high-pressure contrast agent injection (they are intended to enter the arterial vessels in an anterograde direction). In one embodiment, the one-way valve is a low-resistance blood flow valve, for example, described in U.S. Patent No. 5,727,594 or other low-resistance blood flow valves.

[0135] In an embodiment of a shunt comprising both a filter 1145 and a one-way check valve 1115, the check valve is located downstream of the filter. In this configuration, as debris advances into the shunt, it is trapped by the filter before reaching the check valve. Many check valve configurations include a sealing member that seals the housing containing the blood flow lumen. Debris can be trapped between the sealing member and the housing, impairing the valve's ability to seal back pressure.

[0136] The controller 1130 is connected to components of the system 100, including the blood flow control assembly 125, and enables manual and / or automatic adjustment and / or monitoring of regurgitation through the components of the system 100 (e.g., including the shunt 120, arterial access device 110, venous return device 115, and blood flow control assembly 125). For example, a user can manually control components of the blood flow control assembly 125 by moving one or more actuators on the controller 1130. Manual control may include switches, dials or similar components located directly on the controller 1130, or components located away from the controller 1130, such as a foot pedal or similar device. The controller 1130 can also automatically control components of the system 100 without prompting user input. In one embodiment, a user can program software on the controller 1130 to enable such automatic control. The controller 1130 can control the operation of the mechanical parts of the blood flow control assembly 125. The controller 1130 may include electrical circuits or programming to interpret such signals generated by sensors 1135 / 1140, so that the controller 1130 can control the operation of the blood flow control assembly 125 in response to the signals generated by the sensors.

[0137] The depiction of the controller 1130 in Figure 11 is for illustrative purposes only. It should be recognized that the appearance and structure of the controller 1130 can be modified. In Figure 11, the controller 1130 is illustrated as being integrated into a single housing. This allows the user to control the blood flow control assembly 125 from one location. It should be recognized that all components of the controller 1130 can be distributed into separate housings. Furthermore, Figure 11 illustrates the controller 1130 and the blood flow control assembly 125 as separate housings. It should be recognized that the controller 1130 and the blood flow control regulator 125 can be integrated into a single housing, or they can be divided into multiple housings or multiple components.

[0138] Blood flow state indicator(s) The controller 1130 may include one or more indicators (displays) that provide the user with visual and / or audible signals regarding the state of regurgitation. Audible indication is advantageous for making the user aware of the blood flow state without requiring the user to visually check the blood flow controller 1130. The indicators may include a speaker 1150 and / or a light 1155, or any other means for communicating the state of regurgitation to the user. The controller 1130 may control the operation of the indicators through one or more sensors in the system. Alternatively, the operation of the indicators may be directly linked to the user moving one of the blood flow control actuators 1165. The indicators do not have to be speakers or lights. The indicators can be simply buttons or switches that visually indicate the state of regurgitation. For example, a button in a certain state (e.g., pressed or lowered) may visually indicate that regurgitation is in a rapid state. Or, a switch or dial pointing to a specific labeled blood flow state may visually indicate that regurgitation is in a labeled state.

[0139] The indicator can provide a signal indicating one or more states of regurgitation. In one embodiment, the indicator identifies only two distinct states (a "high" blood flow velocity state and a "low" blood flow velocity state). In another embodiment, the indicator identifies two or more blood flow velocities, including a "high" blood flow velocity, a "moderate" blood flow velocity, and a "low" velocity. The indicator can be configured to identify any amount of any of the distinct states of regurgitation, or to identify a graduated signal corresponding to the state of regurgitation. In this case, the indicator can be a digital meter or analog meter 1160 that displays a value of the regurgitation velocity, such as ml / min or other units.

[0140] In one embodiment, the indicator is configured to show the user whether the regurgitation velocity is in a "high" or "low" blood flow velocity state. For example, the indicator may light up in a first manner (e.g., a level of brightness) and / or emit a first audible signal when the blood flow velocity is high, and then change to a second mode of brightness and / or emit a second audible signal when the blood flow velocity is low. Alternatively, the indicator may light up and / or emit an audible signal only when the blood flow velocity is high, or only when the blood flow velocity is low. Considering that some patients cannot tolerate high blood flow velocities or cannot tolerate high blood flow velocities for extended periods, it would be desirable for the indicator to provide notification to the user when the blood flow velocity is high. This serves as a fail-safe feature.

[0141] In another embodiment, the indicator provides a signal (audible and / or visual) when the blood flow velocity changes, for example, when the blood flow velocity changes from a high state to a low state and / or vice versa. In another embodiment, the indicator provides a signal when there is no backflow, for example, when shunt 120 is blocked or when one of the plugs of shunt 120 is closed.

[0142] Blood flow velocity actuators The controller 1130 may include one or more actuators that the user can press, switch, manipulate, or actuate to adjust and / or monitor the velocity of the regurgitating blood flow. For example, the controller 1130 may include a blood flow control actuator 1165 (e.g., one or more buttons, knobs, dials, switches, etc.) that the user can move to selectively change the mode of regurgitation. For example, in the illustrated embodiment, the blood flow control actuator 1165 is a knob that can be rotated to various distinct positions, each corresponding to a controller 1130 that causes the system 100 to achieve a particular regurgitation state. These states include, for example, (a) an OFF state, (b) a LO-FLOW state, (c) a HI-FLOW state, and (d) an ASPIRATE state. It should be recognized that the states described above are merely examples, and different states or combinations of states are also available. The controller 1130 achieves various backflow states by interacting with one or more components of the system, including sensors, valves, variable resistance components, and / or pumps. It should also be recognized that the controller 1130 may also include electrical circuits and software to regulate the backflow rate and / or monitor the blood flow rate, so that the user does not need to actively operate the controller 1130.

[0143] The OFF state corresponds to a state in which there is no regurgitating blood flow through the shunt 120. When the user sets the blood flow control actuator 1165 to OFF, the controller 1130 stops the regurgitation, for example, by tightening the valve or closing the plug on the shunt 120. The low flow state and high flow state correspond to a low regurgitation velocity and a high regurgitation velocity, respectively. When the user sets the blood flow control actuator 1165 to low flow or high flow, the controller 1130 interacts with the components of the blood flow control 125, including the pump 1110, valve 1115 and / or variable resistance component 1125, to increase or decrease the blood flow velocity accordingly. Finally, if active regurgitation is desired, the suction state corresponds to opening the circuit to an inspiratory source (e.g., a vacuum or suction device).

[0144] The system can be used to change blood flow between various states, including active, passive, suction, and off states. The active state corresponds to a system that uses means to actively drive the regurgitating blood flow. Such active means may include, for example, a pump, syringe, or vacuum source. The passive state corresponds to a system where the regurgitating blood flow is driven by the perfusion trunk pressure of the ECA and ICA, and possibly venous pressure. The suction state corresponds to a system that drives the regurgitating blood flow using an inspiratory source (e.g., a vacuum or suction device). The off state corresponds to a system where there is no regurgitating blood flow, such as as a result of closing a stopper or valve. Low and high blood flow velocities can be either passive or active blood flow states. In some embodiments, specific values ​​(e.g., in units of ml / min) for either the low and / or high blood flow velocities can be predetermined and / or pre-programmed within the controller so that the user does not actually set or input the values. More precisely, the user simply selects "high blood flow" and / or "low blood flow" (for example, by pressing an actuator such as a button on the controller 1130), and the controller 1130 interacts with one or more components of the blood flow control assembly 125 so that the blood flow velocity becomes a predetermined high blood flow velocity value or a low blood flow velocity value. In another embodiment, the user sets or inputs the low blood flow velocity and / or high blood flow velocity values, for example, within the controller. In another embodiment, the low blood flow velocity and / or high blood flow velocity are not actually set. More precisely, external data (for example, data from an anatomical data sensor 1140) is used as a reference that acts on the blood flow velocity.

[0145] The blood flow control actuator 1165 may consist of multiple actuators, for example, one actuator (e.g., a button or switch) for switching the state from a low flow state to a high flow state, and another actuator for closing the blood flow loop and turning it off, for example, during the injection of contrast agent when the contrast agent is directed anterogradely into the carotid artery. In one embodiment, the blood flow control actuator 1165 may include multiple actuators. For example, one actuator may be operated to switch the blood flow velocity from low to high, another actuator may be operated to temporarily stop the blood flow, and a third actuator (e.g., a plug) may be operated to aspirate using a syringe. In another example, one actuator may be operated to switch to a low flow state, and another actuator may be operated to switch to a high flow state. Alternatively, the blood flow control actuator 1165 may include multiple actuators for switching from a low flow state to a high flow state, and additional actuators for fine-tuning the blood flow velocity between high and low blood flow velocities. When switching between low and high flow states, these additional actuators can be used to fine-tune the blood flow velocity within those states. Thus, it should be understood that various blood flow velocities can be fine-tuned by turning a dial in each state (i.e., high and low blood flow states). A wide variety of actuators can be used to achieve control over blood flow states.

[0146] The controller 1130, or its individual components, can be positioned in various locations relative to the patient and / or other components of the system 100. For example, when introducing an intervention tool to a patient, the blood flow control actuator 1165 can be placed near the hemostatic valve to facilitate access to it during tool introduction. As shown in Figures 1A-C, the placement may be changed based on whether, for example, a transfemoral or transcervical approach is used. The controller 1130 can have wireless and / or adjustable-length wired connections to the rest of the system 100 to enable remote control of the system 100. The controller 1130 can also have wireless and / or adjustable-length wired connections to the blood flow control regulator 125 to enable remote control of the blood flow control regulator 125. The controller 1130 can also be integrated with the blood flow control regulator 125. When the controller 1130 is mechanically connected to a component of the blood flow control assembly 125, the controller 1130 can be connected to one or more components within the range of its mechanical operating capability (tether). In one embodiment, the controller 1130 can be positioned outside the radiation field when fluoroscopy is being used by positioning it at a sufficient distance from the system 100.

[0147] The controller 1130 and its components can interact with other components of the system (e.g., pumps, sensors, shunts, etc.) in various ways. For example, various mechanical connections can be used to enable communication between the controller 1130 and the components of the system. Alternatively, the controller 1130 can communicate with the components of the system electronically or magnetically. Electromechanical connections can also be used. The controller 1130 can be equipped with control software that enables the controller to implement functions for controlling the components of the system. The controller itself can be a mechanical, electrical, or electromechanical device. The controller can be moved mechanically, pneumatically, or hydraulically, or electromechanically (e.g., in the case of solenoid operation in a blood flow control state). The controller 1130 can include a computer, computer processor, and memory, as well as data storage capabilities.

[0148] Figure 12 shows a typical embodiment of the variable blood flow control element 1125. In this embodiment, the blood flow resistance through the shunt 120 may be modified by providing two or more alternative blood flow paths that create blood flow paths of low and high resistance. As shown in Figure 12A, the blood flow through the shunt 120 passes through the primary lumen 1700 and the secondary lumen 1705. The secondary lumen 1705 is longer and / or has a smaller radius than the primary lumen 1700. Therefore, the secondary lumen 1705 has higher blood flow resistance than the primary lumen 1700. By blood passing through both of these lumen, the blood flow resistance is minimized. Blood can flow through both lumen 1700 and 1705 by a drop in blood pressure created in the primary lumen 1700 across the inlet and outlet of the secondary lumen 1705. This has the advantage of preventing blood stagnation. As shown in Figure 12B, by blocking blood flow through the primary lumen 1700 of the shunt 120, all blood flow is diverted to the secondary lumen 1705, thus increasing blood flow resistance and decreasing blood flow velocity. It should be noted that additional blood flow lumens may be provided, allowing for three, four, or more separate parallel blood flow resistances. The shunt 120 may include a valve 1710 that controls blood flow to the primary lumen 1700 and the secondary lumen 1705. The position of the valve may be controlled by an actuator, such as a button or switch on the housing of the blood flow controller 125. The embodiments in Figures 12A and 12B have the advantage that they maintain the correct blood flow lumen size, even at the slowest blood flow settings. The size of the secondary blood flow lumen can be configured to prevent thrombus formation, even under the slowest or continuous blood flow conditions. In one embodiment, the inner diameter of the lumen of the secondary lumen 1705 is 0.063 inches or larger.

[0149] Figures 13A–C illustrate an embodiment of a blood flow controller 125, comprising many blood flow shunt components and features contained within or enclosed in a single housing 1300. This configuration simplifies and reduces the space required for the blood flow controller 125 and the blood flow shunt 120. As shown in Figure 13A, the housing 1300 includes a variable blood flow element 1125 of the type illustrated in Figure 12. An actuator 1330 moves a valve 1710 back and forth, transitioning the blood flow resistance in the shunt between a low resistance state and a high resistance state. In Figure 13A, the valve is in the open position, with a shunt in a low resistance (high flow) state. In Figure 13B, the valve is in the closed position, and the shunt is in a high resistance (low flow) state. A second actuator 1340 moves a second valve 1720 back and forth, opening and closing the shunt line 120. In Figures 13A and 13B, the valve 1720 is in the open position, allowing blood flow through the shunt 120. In Figure 13C, valve 1720 is in the closed position, completely stopping blood flow in shunt 120. The housing 1300 also includes a filter 1145 and a one-way check valve 1115. In one embodiment, the housing may be opened after the procedure and the filter 1145 may be removed. This embodiment has the advantage that the filter may be rinsed and inspected after the procedure so that the physician can obtain direct visual evidence of the embolism debris captured by the system during the procedure.

[0150] In a preferred embodiment, the connectors connecting the elements of the regurgitation system are large-bore, quick-connect type connectors. For example, a large-bore male hub 680 on a Y-adapter 660 of an arterial sheath 110, as shown in Figure 9B, connects to a female counterpart 1320 on the arterial side of a blood flow shunt 120, as shown in Figure 13. Similarly, a large-bore male connector 1310 on the venous side of a blood flow shunt 120 connects to a female counterpart connector 1310 on the blood flow line of a venous sheath 115, as shown in Figure 10C. The connected regurgitation system 100 is shown in Figure 1E. This preferred embodiment reduces blood flow resistance through the blood flow shunt, thus enabling a faster blood flow velocity, and also prevents the blood flow shunt from being accidentally reversed (with a check valve in the wrong position). In an alternative embodiment, the connections are standard female and male Luer connectors or other types of tubing connectors.

[0151] <Sensor> As described above, the blood flow control assembly 125 may include or interact with one or more sensors, which are in contact with the system 100 and / or with the patient's tissue. Each sensor may be suitable for responding to physical stimuli (e.g., including heat, light, sound, pressure, magnetism, motion, etc.) and may also be suitable for transmitting signals obtained for measurement or display or for operating the controller 1130. In one embodiment, the blood flow sensor 1135 interacts with the shunt 120 to detect the condition of the blood flow through the shunt 120 (e.g., blood flow velocity or volumetric flow rate). The blood flow sensor 1135 may be directly connected to a display that directly displays the volumetric flow rate or velocity value of the blood flow. Alternatively, the blood flow sensor 1135 may input volumetric flow rate or velocity data for display to the controller 1130.

[0152] The type of blood flow sensor 1135 can be changed. The blood flow sensor 1135 may be a mechanical device, such as a paddle wheel, a flapper valve, a rolling ball, or a mechanical component that responds to the blood flow through the shunt 120. The movement of the mechanical device in response to the blood flow through the shunt 120 can serve as a visual indicator of the flow rate and can also be calibrated to a scale as a visual indicator of the fluid velocity. The mechanical device can be connected to an electrical component. For example, a paddle wheel can be positioned within the shunt 120 such that the flow rate causes the paddle wheel to rotate, with the greater the flow rate, the greater the rotational speed of the paddle wheel. The paddle wheel can be magnetically connected to a Hall effect sensor to detect its rotational speed, which indicates the flow velocity through the shunt 120.

[0153] In one embodiment, the blood flow sensor 1135 is an ultrasonic, electromagnetic, or electro-optical flowmeter that enables blood flow measurement through the walls of the shunt 120 without contact with the blood. The ultrasonic or electromagnetic flowmeter can be configured so that it does not need to contact the lumen of the shunt 120. In another embodiment, the blood flow sensor 1135 includes, at least partially, a Doppler flowmeter (e.g., a transonic flowmeter) that measures the flow rate through the shunt 120. In yet another embodiment, the blood flow sensor 1135 measures the pressure difference along the blood flow line to determine the flow rate. It should be recognized that a wide variety of sensor types can be used, including ultrasonic flowmeters and transducers. Furthermore, the system may include multiple sensors.

[0154] The system 100 is not limited to using a blood flow sensor 1135 located within the shunt 120, or a sensor that interacts with a venous return device 115 or an arterial access device 110. For example, an anatomical data sensor 1140 may communicate with or interact with patient tissue (e.g., patient neurological tissue). In this configuration, the anatomical data sensor 1140 may detect the condition of a measurable tissue that is directly or indirectly related to the regurgitation velocity from the carotid artery. For example, the anatomical data sensor 1140 may measure blood flow conditions in the brain (e.g., blood flow velocity in the middle cerebral artery) and communicate such conditions to a controller 1130 for display and / or for adjusting the regurgitation velocity based on predetermined criteria. In one embodiment, the anatomical data sensor 1140 includes transcranial Doppler ultrasound (TCD), which is an ultrasound examination that uses reflected sound waves to assess blood flow through the brain. The use of TCD yields a TCD signal, which can be communicated to a controller 1130 for controlling the regurgitation velocity to achieve or maintain a desired TCD profile. The anatomical data sensor 1140 can be based on physiological measurements, including regurgitation velocity, blood flow through the middle cerebral artery, TCD signals from embolic particles, or other neuromonitoring signals.

[0155] In one embodiment, system 100 includes a closed-loop control system. In the closed-loop control system, one or more sensors (such as a blood flow sensor 1135 or an anatomical data sensor 1140) detect or monitor predetermined conditions of system 100 or tissue (e.g., regurgitation velocity and / or neurological monitoring signals). The sensors input relevant data to controller 1130, which continuously adjusts the system conditions as needed to maintain a desired regurgitation velocity. The sensors provide feedback on how system 100 is operating controller 1130 so that controller 1130 can translate the data and drive components of blood flow control regulator 125 to dynamically compensate for disturbances in regurgitation velocity. For example, controller 1130 may include software that causes controller 1130 to send signals to components of blood flow control assembly 125 to adjust blood flow velocity so that it is maintained at a constant level despite varying blood pressure from the patient. In this embodiment, the system 100 does not need to rely on the user to determine when, for how long, and / or by what value to set the backflow velocity to a high or low state. Rather, the software within the controller 1130 can govern such factors. In a closed-loop system, the controller 1130 can control the components of the blood flow control assembly 125 to establish a level or state of backflow (either an analog level or individual states such as high, low, baseline, intermediate, etc.) based on the backflow velocity detected by the sensor 1135.

[0156] In this embodiment, an anatomical data sensor 1140 (which measures the patient's physiological measurements) transmits a signal to a controller 1130, which adjusts the blood flow velocity based on the signal. For example, the physiological measurements may be based on flow velocity through the MCA, a TCD signal, or other cerebral vascular signals. In the case of a TCD signal, the TCD may be used to monitor changes in cerebral blood flow and detect microembolus. The controller 1130 may adjust the blood flow velocity to maintain the TCD signal within a desired profile. For example, the TCD signal may indicate the presence of microembolus ("TCD hits"), and the controller 1130 may adjust the regurgitating blood flow velocity to keep the TCD hits below a threshold for TCD hits. (See Ribo et al., "Transcranial Doppler Monitoring of Transcervical Carotid Stenting with Flow Reversal Protection: A Novel Carotid Revascularization Technique," Stoke 2006, 37, 2846-2849, and Shekel et al., "Experience of 500 Cases of Neurophysiological Monitoring in Carotid Endarterectomy," Acta Neurochir, 2007, 149:681-689. These are incorporated herein by reference in their entirety.)

[0157] In the case of MCA blood flow, the controller 1130 can set the regurgitation velocity to the "maximum" blood flow velocity that the patient can tolerate, as assessed by perfusion to the brain. The controller 1130 can optimize the level of patient protection by controlling the regurgitation velocity without relying on user intercede. In another embodiment, the feedback is based on the state of the device or intervention tool used in system 100. For example, when system 100 is in a high-risk state (e.g., when the intervention catheter is located inside the sheath 605), the sensor may notify the controller 1130. The controller 1130 then adjusts the blood flow velocity to compensate for such a state.

[0158] The controller 1130 can be used to selectively increase regurgitation in various forms. For example, it has been observed that higher regurgitation velocities result in a greater drop in blood flow toward the brain, most importantly in the ipsilateral MCA, which may not be adequately compensated for by collateral flow from the Circle of Willis. Thus, prolonged high regurgitation velocities can lead to a situation where the patient's brain does not receive sufficient blood flow, which the patient cannot tolerate and may manifest as neurological symptoms. Studies have shown that MCA blood flow velocities below 10 cm / sec are the threshold below which the patient is at risk of neurological blood deficiency. Other markers (e.g., EEG signals) exist to monitor adequate perfusion to the brain. However, even high blood flow velocities that lead to a complete cessation of blood flow to the MCA may be tolerable for short periods of about 15 seconds to 1 minute.

[0159] Thus, the controller 1130 can optimize the capture of embolic debris by automatically increasing regurgitation only for limited periods corresponding to periods of high risk of embolism during surgery. High-risk periods include the period when the intervention device (inflation balloon before and after stent expansion or stent delivery device) crosses the plaque P. Another period is during intervention operations such as stent deployment or inflation or deflation of the balloon before and after expansion. A third period is during contrast agent injection for angiographic imaging of the treatment area. During low-risk periods, the controller can return the regurgitation velocity to a lower baseline level. This lower level may correspond to a low regurgitation velocity in the ICA, or to slight antegrade blood flow in the patient with a high perfusion pressure ratio of the ECA to the ICA.

[0160] In blood flow control systems where the user manually sets the blood flow state, there is a risk that the user may not pay attention to the backflow state (high or low) and inadvertently maintain the circuit at a high blood flow. This could later cause an adverse patient response. In one embodiment, as a safety mechanism, the initial value of the blood flow velocity is a low blood flow velocity. This serves as a fail-safe measure for patients who cannot tolerate high blood flow velocities. In this regard, the controller 1130 can be biased toward the initial velocity value so that after a predetermined time has elapsed at a high blood flow velocity, the system returns to a low blood flow velocity by the controller. The bias toward a low blood flow velocity can be achieved by electronics or software, or by using mechanical components or a combination thereof. In one embodiment, the blood flow control actuator 1165 and / or valve 1115 and / or pump 1110 of the blood flow control regulator 125 of the controller 1130 are spring-loaded toward a state that achieves a low blood flow velocity. The controller 1130 is configured so that the user has priority over the controller 1130 so that the system can be manually returned to a low blood flow velocity state if necessary.

[0161] In another safety mechanism, the controller 1130 includes a timer 1170 (Figure 11) that records the duration of the high blood flow velocity. The controller 1130 can be programmed to automatically return the system 100 to a low blood flow velocity after a predetermined period (e.g., 15, 30, 60 seconds or more) has elapsed at the high blood flow velocity. After the controller returns to the low blood flow velocity, the user can, if necessary, initiate another predetermined period at the high blood flow velocity. Furthermore, the user can override the controller 1130 and move the system 100 to a desired low (or high) blood flow velocity.

[0162] In an exemplary procedure, the capture of embolic debris is optimized without causing patient tolerance issues by initially setting a low regurgitation level and then switching to a high level only for individual periods during critical phases of the procedure. Alternatively, the blood flow velocity is initially set to a high level, and the patient's tolerance to that level is checked before continuing the rest of the procedure. If the patient shows signs of intolerance, the regurgitation velocity is reduced. The patient's tolerance may be determined automatically by the controller based on feedback from the anatomical data sensor 1140, or it may be determined by the user based on observation of the patient. The adjustment of the regurgitation velocity can be done automatically by the controller or manually by the user. Alternatively, the user may monitor the flow velocity through the middle cerebral artery (MCA) using, for example, a TCD, and set it to the maximum level of regurgitation that can maintain an MCA flow velocity above a threshold level. In this situation, the entire procedure may be performed without modifying the blood flow state. If the MCA flow velocity changes during the course of the procedure, or if the patient shows neurological symptoms, the necessary adjustments will be made.

[0163] Typical kit configuration and package design In a typical embodiment of the backflow system 100, all components of the backflow system, including an arterial sheath, arterial sheath dilator, venous sheath, venous sheath dilator, blood flow shunt / blood flow controller, and one or more sheath guidewires, are packaged together in a single, sterile package. In one configuration, the components are placed on a flat card, such as a cardboard or polymer card, which has one or more openings or cutouts, sized and shaped to receive and close the components. In another configuration, the card is configured to open and close in a book-like manner or in any clamshell manner, reducing the overall shape of the package. In this embodiment, the card may have cutouts that allow at least a portion of the product to be visible when in the closed position. Figure 15A shows a kit placed on an open book card 1510. Figure 15B shows a kit with a closed book card. The cutouts 1520 allow visualization of at least one portion of the package device, such as the blood flow controller housing 1300, even when the card is in the closed position. Figure 15C shows a kit and book card inserted into additional packaging components, including a sterile bag 1530 and a shelf carton 1540. In this embodiment, the shelf carton 1540 also includes cutouts 1550, which are aligned in a row with the cutouts 1520 in the book card, as shown in Figure 15D, allowing visualization of at least a portion of the product from the outside of the closed shelf carton. To protect the sterile bag from soiling or damage, nylon or other transparent film material may be affixed to the window of the shelf carton.

[0164] In one embodiment, a package card, either flat or book-shaped, may be printed with the names of the components, connection instructions, and / or adjustment instructions to assist in the adjustment and use of the device.

[0165] In an alternative embodiment, the blood flow shunt, including the arterial access device, venous return device, and blood flow controller, is packaged in three separate sterile packages. For example, the arterial access device, including the arterial access sheath, sheath dilator, and sheath guidewire, is placed in a first sterile package; the venous return device, including the venous return sheath, venous sheath dilator, and sheath guidewire, is placed in a second sterile package; and the blood flow shunt, including the blood flow controller, is placed in a third sterile package.

[0166] Examples of usage Referring to Figures 14A–14E, blood flow through the carotid bifurcation at different stages of the method disclosed herein is described. Initially, as shown in Figure 14A, the distal sheath 605 of the arterial access device 110 is introduced into the common carotid artery CCA. As described above, access to the common carotid artery CCA may be made via a transcervical or transfemoral approach, and may be either by direct surgical incision or percutaneous access. After the sheath 605 of the arterial access device 110 is introduced into the common carotid artery CCA, as shown in Figure 14A, blood flow continues in the anterograde direction AG, and the blood flow will enter both the internal carotid artery ICA and the external carotid artery ECA from the common carotid artery.

[0167] Subsequently, the venous return device 115 is inserted into a venous return site such as the internal jugular vein (IJV) (not shown in Figures 14A-14E) or the femoral vein. A shunt 120 is used to connect the blood flow lines 615 and 915 of the arterial access device 110 and the venous return device 115, respectively (as shown in Figure 1A). In this configuration, the shunt 120 provides a passage for backflow from the arterial access device 110 to the venous return device 115. In another embodiment, as shown in Figure 1C, the shunt 120 is connected to an external receptacle 130 instead of the venous return device 115.

[0168] Once all components of the system are in place and connected, blood flow through the common carotid artery (CCA) is typically occluded and stopped using a hemostatic device 2105 or other external vascular occlusion device. In an alternative embodiment, the occlusion element 129 is located at the distal end of the arterial access device 110. Alternatively, as shown in Figure 2B, the occlusion element 129 is introduced in a second occlusion device 112, separated from the distal sheath 605 of the arterial access device 110. The ECA may be occluded by separate occlusion elements on the same device 110 or on separate occlusion devices.

[0169] At that point, reflux RG will begin from the external carotid artery (ECA) and internal carotid artery (ICA), flowing through the sheath 605, blood flow line 615, shunt 120, and then through blood flow line 915 to the venous return device 115. The blood flow control assembly 125 regulates the reflux as described above. Figure 14B shows the onset of reflux RG. While the reflux is maintained, the stent delivery catheter 2110 is introduced into the sheath 605, as shown in Figure 14C. The stent delivery catheter 2110 is introduced into the sheath 605 through the hemostatic valve 615 and the proximal extension 610 of the arterial access device 110 (not shown in Figures 14A-14E). As shown in Figure 14D, the stent delivery catheter 2110 is advanced into the internal carotid artery (ICA), and the stent 2115 is deployed at bifurcation B.

[0170] For example, the regurgitation velocity can be increased during periods of high risk of embolism, such as while the stent delivery catheter 2110 is being introduced or, optionally, while the stent 2115 is being deployed. The regurgitation velocity can also be increased during the placement and inflation of the expansion balloon before and after stent deployment. Atherectomy can also be performed under regurgitation conditions prior to stent placement.

[0171] Optionally, after expanding stent 2115, bifurcation B can be flushed by repeatedly alternating between low and high blood flow velocities. Before restoring normal blood flow, the area of ​​the carotid artery where the stent was deployed or other procedures were performed may be flushed with blood. In particular, while the common carotid artery remains occluded, the internal carotid artery may be completely occluded by advancing and deploying a balloon catheter or other occluding element into it. The same procedure may also be used to perform a post-deployment stent dilatation, which is now typically done in self-expanding stent procedures. Subsequently, the occluding element present in the artery may be temporarily opened to restore blood flow from the common carotid artery to the external carotid artery. The resulting blood flow (slow, turbulent, or stagnant blood flow during carotid occlusion in the external carotid artery) will be able to flush the common carotid artery. Furthermore, the same balloon may be positioned distal to the stent during regurgitation, and forward flow may be established by temporarily removing and flushing the occlusion of the common carotid artery. In this way, a flushing action occurs in the stented area, which helps to remove any loose or loosely attached embolic debris in that area.

[0172] Optionally, while blood flow from the common carotid artery continues and the internal carotid artery remains occluded, further free embolus from the treated area can be removed by means of measures. For example, mechanical elements may be used to wash or remove plaque or other potential embolic debris that is free or loosely attached within the stent, or the area may be washed using a catheter that delivers a thrombolytic agent or other fluid, or other procedures may be performed. For example, treatment for in-stent restenosis with a balloon, atherectomy, or additional stent can be performed under retrograde flow. In another embodiment, the occluding balloon catheter may include a lumen or channel for blood flow or aspiration that opens proximal to the balloon. Without requiring additional devices, saline, a thrombolytic agent, or other fluid may be injected into or from the treated area, and / or blood and debris may be aspirated. The embolus thus released may flow into the external carotid artery, although the external carotid artery is generally less sensitive to embolic release than the internal carotid artery. Prophylactically removing any remaining potential emboli further reduces the risk of emboli being released when blood flow to the internal carotid artery is restored. Embolisms can also be released under regurgitation, potentially leading to them flowing through shunt 120 into the venous system, the filter within shunt 120, or receptacle 130.

[0173] After the embolus is removed from the bifurcation, the occlusive element 129 or the alternative hemostatic device 2105 can be removed to reconstruct antegrade blood flow, as shown in Figure 14E. The sheath 605 can then be removed.

[0174] Before withdrawing the sheath 605 after the procedure is complete, a self-closing element may be deployed around the penetration site in the wall of the common carotid artery. Typically, the self-closing element is deployed at or near the start of the procedure, but optionally, it may also be deployed when the sheath is withdrawn, often when the distal end of the sheath is released from the wall of the common carotid artery. The use of a self-closing element is advantageous because it substantially acts to rapidly close the penetration site in the common carotid artery as the sheath is withdrawn. Such rapid closure can reduce or eliminate unintended blood loss either at the end of the procedure or while the sheath is accidentally removed. Furthermore, such a self-closing element will reduce the risk of dissection of the arterial wall during access. In addition, the self-closing element may be configured to exert a frictional or other retention force on the sheath during the procedure. Such a retention force is advantageous and can reduce the likelihood of the sheath being accidentally removed during the procedure. The auto-closing element eliminates the need for surgical suturing of the artery with sutures after sheath removal, reduces the need for a large surgical field, and significantly reduces the surgical skill required for the procedure.

[0175] The disclosed systems and methods may utilize a wide variety of self-closing elements, typically mechanical elements comprising an anchor portion and a self-closing portion. The anchor portion may include hooks, pins, staples, clips, teeth, sutures, etc., which engage around the penetration on the outer surface of the common carotid artery to secure the self-closing element when the penetration is fully open. The self-closing element may include a spring-like or other self-closing portion, which will close the anchor portion upon sheath removal to provide closure and pull in tissue within the arterial wall. Usually, the closure is sufficient and no further measures will be needed to close or seal the penetration. However, optionally, it may be desirable to provide auxiliary sealing of the self-closing element after the sheath has been withdrawn. For example, the self-closing element and / or tissue tract within the element may be treated with hemostatic materials such as bioabsorbable polymers, collagen plugs, adhesives, sealants, coagulation factors, or other procoagulants. Alternatively, the tissue or self-closing element may be sealed using other sealing protocols such as electrocautery, suturing, clipping, or stapling. Alternatively, the self-closing element may be a self-sealing membrane or gasket material attached to the outer wall of a blood vessel by clips, adhesives, bands, or other means. The self-sealing membrane may have an internal opening, such as a slit or cross-cut, which would normally close in resistance to blood pressure. These self-closing elements may be designed to be placed by an incisional surgical procedure or to be deployed percutaneously.

[0176] In another embodiment, carotid artery stenting may be performed after a sheath is placed in the external carotid artery and an occlusive balloon catheter is deployed. The stent, which has a lateral opening, or other elements intended not to obstruct the external carotid artery orifice, is delivered through a sheath with a guidewire or the shaft of the external carotid artery occlusive balloon, which is received through the lateral opening. Thus, if the stent is advanced by a catheter introduced on a guidewire typically extending into the internal carotid artery, the presence of the catheter shaft in the lateral opening will ensure that the lateral opening aligns with the external carotid artery orifice as the stent is advanced. When the occlusive balloon is deployed in the external carotid artery, the lateral opening prevents the trapping of the external carotid artery occlusive balloon shaft with the stent, which is a drawback of other blood flow reversal systems. This approach also avoids "jailing" the external carotid artery and avoids obstructing blood flow to the external carotid artery if the stent is covered with graft material.

[0177] In another embodiment, a stent is placed that has a shape substantially conforming to the pre-existing angle between the common and internal carotid arteries. Due to significant tissue variations between patients, the bifurcation between the internal and external carotid arteries will have a wide range of angles and shapes. By providing a group of stents with different geometric shapes, or by providing individual stents that can be molded by the physician prior to deployment, the physician can select a stent that matches the patient's specific tissue prior to deployment. The patient's tissue will be determined using angiography or other conventional means. As a further alternative, the stent may have an articulated portion. These stents may be placed first and then articulated in situ to match the angle of the bifurcation between the common and internal carotid arteries. The stent may also be placed in the carotid artery, where the stent has side walls with zones of different densities.

[0178] In another embodiment, the stent would be placed such that one or both ends of the stent are at least partially covered with graft material. Generally, the stent would not have graft material, nor would it have an intermediate portion of the stent deployed adjacent to the external carotid artery orifice to allow blood flow from the common carotid artery to the external carotid artery.

[0179] In another embodiment, the stent delivery system can be optimized for transcervical access by being shorter and / or stiffer than systems designed for transfemoral access. These modifications would enhance the ability to precisely torque and position the stent during deployment. Furthermore, the stent delivery system can be designed to align the stent with the external carotid artery orifice by using either an external carotid artery occlusion balloon within the external carotid artery or a separate guidewire, which is particularly useful for stents with lateral holes or stents with curved, bent, or angled sections in areas where orientation is critical.

[0180] In one embodiment, the shunt may be fixedly connected to the arterial access sheath and venous return sheath, and the entire sheath assembly, including the replaceable blood flow assembly, may be disposable and replaceable as a single unit. In other examples, the blood flow control assembly may be detachably attached to one or both sheaths.

[0181] In one embodiment, the user first determines whether there are periods during the procedure when the risk of embolism is high. As described above, typical high-risk periods include (1) the period during which the device crosses the plaque P, (2) during the interventional procedure, such as during stent delivery or during inflation or deflation of the balloon catheter or guidewire, and (3) during contrast agent injection. The above are merely examples of high-risk periods. During such periods, the user sets a high-speed regurgitation for each period. When the high-risk period is over, or if the patient shows intolerance to the high blood flow velocity, the user returns the blood flow state to baseline blood flow. If the system has a timer, the blood flow state automatically returns to baseline blood flow after the set period has elapsed. In this case, if the procedure is still in a high-risk period for embolism, the user may set the blood flow state to a high blood flow velocity again.

[0182] In another embodiment, if the patient is intolerant to the presence of reflux, the reflux is established only while the filter is positioned distal to the plaque P within the ICA. The reflux is then stopped while the intervention is performed on the plaque P. The reflux is then re-established while the filter is removed. In yet another embodiment, the filter is positioned distal to the plaque P within the ICA, and reflux is established while the filter is in place. In this embodiment, the use of a distal filter is combined with reflux.

[0183] While various methods and embodiments of apparatus are described in detail herein with reference to several types, it should be recognized that other types, embodiments, methods of use, and combinations thereof are also possible. Therefore, the spirit and scope of the appended claims should not be limited to the embodiments described herein. The disclosures in this specification may include the following aspects: (Aspect 1) A transcervical access device: An arterial access sheath having a sheath body that defines an internal lumen, wherein the size and shape of the sheath body are determined so that it is introduced into the common carotid artery and receives blood flow from the artery; An elongated tube attached to the proximal end of the sheath body, wherein a connector connects the tube to the sheath body; An adapter located at the proximal end of the elongated tube, the adapter having a hub adapted for detachable connection to a blood flow shunt line, the adapter further having a valve positioned close to the internal lumen of the transcervical access device, the valve controlling the flow from the internal lumen of the transcervical access device to the hub; A proximal extension portion that connects to the proximal end of the adapter, the proximal extension portion being formed from an elongated body; A hemostatic valve located at the proximal end of the proximal extension such that the proximal extension positions the hemostatic valve away from the adapter; and A transcervical access device including a flushing line that connects to the proximal end of a proximal extension and provides a fluid passage within the sheath body for flushing. (Aspect 2) The transcervical access device according to embodiment 1, further comprising a small hole located on a connector for connecting the elongated tube to an adapter. (Aspect 3) The transcervical access device according to embodiment 1, wherein the valve transitions between an open state that allows blood flow from the internal lumen of the transcervical access device and a closed state that blocks blood flow from the internal lumen of the transcervical access device. (Aspect 4) The transcervical access device according to embodiment 1, further comprising a sheath stopper which can be positioned on the sheath body so as to cover a portion of the sheath body and expose a portion of the sheath body, wherein the sheath stopper restricts the insertion of the sheath body into the carotid artery so as to expose the distal portion of the sheath body, and a flange is positioned at the distal end of the sheath stopper. (Appendix 5) A trans-neck access device according to embodiment 4, wherein the flange is expandable or mechanically expandable. (Aspect 6) A transcervical access device: An arterial access sheath having a sheath body that defines an internal lumen, wherein the size and shape of the sheath body are determined so that it is introduced into the common carotid artery and receives blood flow from the artery; An adapter located at the proximal end of a sheath body, the adapter having a hub adapted for detachable connection to a blood flow shunt line, the adapter further having a valve positioned close to the internal lumen of a transcervical access device, the valve controlling the flow from the internal lumen of the transcervical access device to the hub; A proximal extension portion that connects to the proximal end of an adapter, formed from an elongated body; A hemostatic valve located at the proximal end of the proximal extension such that the proximal extension positions the hemostatic valve away from the adapter; and A transcervical access device including a flushing line that connects to the proximal end of a proximal extension and provides a fluid passage within the sheath body for flushing. (Aspect 7) A transcervical access device according to embodiment 6, further comprising a small hole located on a connector for connecting the sheath body to an adapter. (Pattern 8) The transcervical access device according to embodiment 6, wherein the valve transitions between an open state that allows blood flow from the internal lumen of the transcervical access device and a closed state that blocks blood flow from the internal lumen of the transcervical access device. (Aspect 9) The transcervical access device according to embodiment 6, further comprising a sheath stopper which can be positioned on the sheath body so as to cover a portion of the sheath body and expose a portion of the sheath body, wherein the sheath stopper restricts the insertion of the sheath body into the carotid artery so as to expose the distal portion of the sheath body, and a flange is positioned at the distal end of the sheath stopper. (Aspect 10) The adapter further includes a hub and a detachably connected blood flow shunt line, and further includes a single housing on the blood flow shunt line, the housing being: A blood flow control element that can move between low-flow and high-flow states of blood flow through a blood flow shunt; A valve that can switch between an open state, which allows blood flow through a blood flow shunt, and a closed state, which blocks blood flow through the blood flow shunt; Fluid filters; and A transcervical access device according to embodiment 1 or 6, comprising a one-way check valve. (Aspect 11) The apparatus according to embodiment 10, wherein the blood flow shunt line switches the flow rate from the access device to the return site.

Claims

1. An access sheath having a sheath body that defines an internal lumen, wherein the size and shape of the sheath body are determined so as to be introduced into a carotid artery and to receive blood flow from the carotid artery; An adapter located at the proximal end of the sheath body, the adapter comprising a valve and a hub, the hub being configured to be detachably connected to a blood flow shunt line; A slender body forming a proximal extension that connects to the proximal end of the adapter; A hemostatic valve located at the proximal end of the proximal extension such that the proximal extension is positioned away from the adapter; and A device for accessing the cerebrovascular system via the carotid artery, comprising a sheath stopper detachably disposed on the sheath body so as to cover a portion of the sheath body and expose a portion of the sheath body, wherein the sheath stopper restricts the insertion of the sheath body into the carotid artery to the exposed distal portion of the sheath body, and a flange is disposed at the distal end of the sheath stopper, and the sheath stopper includes a cutout along the length of the sheath stopper.

2. An access sheath having a sheath body that defines an internal lumen, wherein the size and shape of the sheath body are determined so as to be introduced into a carotid artery and to receive blood flow from the carotid artery; An elongated tube attached to the proximal end of the sheath body, wherein a connector connects the tube to the sheath body; An adapter located at the proximal end of the sheath body, the adapter comprising a valve and a hub, the hub being configured to be detachably connected to a blood flow shunt line; A slender body forming a proximal extension that connects to the proximal end of the adapter; A hemostatic valve located at the proximal end of the proximal extension such that the proximal extension is positioned away from the adapter; and A device for accessing the cerebrovascular system via the carotid artery, comprising a sheath stopper detachably disposed on the sheath body so as to cover a portion of the sheath body and expose a portion of the sheath body, wherein the sheath stopper restricts the insertion of the sheath body into the carotid artery to the exposed distal portion of the sheath body, and a flange is disposed at the distal end of the sheath stopper, and the sheath stopper includes a cutout along the length of the sheath stopper.

3. The device according to claim 2, further comprising a small hole located on a connector that connects the elongated tube to the adapter.

4. The device according to claim 1, further comprising a small hole located on a connector that connects the sheath body to the adapter.

5. The device according to claim 1 or 2, wherein the valve is configured to transition between an open state that allows blood flow from the internal lumen of the device and a closed state that blocks blood flow from the internal lumen of the device.

6. The device according to claim 1 or 2, wherein the flange is expandable or mechanically expandable.

7. Further comprising a blood flow shunt line detachably connectable to the hub of the adapter, further comprising a single housing on the blood flow shunt line, the housing being: A blood flow control element capable of moving blood flow between a low-flow state and a high-flow state through the aforementioned blood flow shunt line; A valve that can transition between an open state that allows blood flow through the blood flow shunt line and a closed state that blocks blood flow through the blood flow shunt line; Fluid filters; and The device according to claim 1 or 2, further comprising a one-way check valve.

8. The device according to claim 7, wherein the blood flow shunt line is configured to switch the flow rate from the access device to the return site.

9. The device according to claim 1 or 2, wherein the sheath body includes a reduced-diameter distal region.

10. The device according to claim 1 or 2, wherein the cutout forms a torsional structure to increase the flexibility of the sheath stopper and maintain the strength of the axis that allows the forward force of the sheath stopper against the wall of the artery.

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