Patent Description:
Interventional procedures are performed to treat vascular disease, for example stenosis, occlusions, aneurysms, or fistulae. Interventional procedures are also used to perform procedures on organs or tissue targets that are accessible via blood vessels, for example denervation or ablation of tissue to intervene in nerve conduction, embolization of vessels to restrict blood flow to tumors or other tissue, and delivery of drugs, contrast, or other agents to intra or extravascular targets for therapeutic or diagnostic purposes. Interventional procedures are typically divided into coronary, neurovascular, and peripheral vascular categories. Most procedures are performed in the arterial system via an arterial access site.

Methods for gaining arterial access to perform these procedures are well-established, and fall into two broad categories: percutaneous access and surgical cut-down. The majority of interventional procedures utilize a percutaneous access. For this access method, a needle puncture is made from the skin, through the subcutaneous tissue and muscle layers to the vessel wall, and into the vessel itself. Vascular ultrasound is often used to image the vessel and surrounding structures, and facilitate accurate insertion of the needle into the vessel. Depending on the size of the artery and of the access device, the method will vary, for example a Seldinger technique or modified Seldinger technique consists of placing a sheath guide wire through the needle into the vessel. Typically the sheath guide wire is <NUM> or <NUM> (<NUM>" or <NUM>"). In some instances, a micro-puncture or micro access technique is used whereby the vessel is initially accessed by a small gauge needle, and successively dilated up by a 4F micropuncture cannula through which the sheath guidewire is placed. Once the guidewire is placed, an access sheath and sheath dilator are inserted over the guide wire into the artery. In other instances, for example if a radial artery is being used as an access site, a smaller sheath guidewire is used through the initial needle puncture, for example a <NUM> (<NUM>") guidewire. The dilator of a radial access sheath is designed to accommodate this smaller size guidewire, so that the access sheath and dilator can be inserted over the <NUM> (<NUM>") wire into the artery.

In a surgical cut-down, a skin incision is made and tissue is dissected away to the level of the target artery. This method is often used if the procedure requires a large access device, if there is risk to the vessel with a percutaneous access, and/or if there is possibility of unreliable closure at the access site at the conclusion of the procedure. Depending on the size of the artery and of the access device, an incision is made into the wall of the vessel with a blade, or the vessel wall is punctured directly by an access needle, through which a sheath guide wire is placed. The micropuncture technique may also be used to place a sheath guide wire. As above, the access sheath and sheath dilator are inserted into the artery over the sheath guide wire. Once the access sheath is placed, the dilator and sheath guide wire are removed. Devices can now be introduced via the access sheath into the artery and advanced using standard interventional techniques and fluoroscopy to the target site to perform the procedure.

Access to the target site is accomplished from an arterial access site that is easily entered from the skin. Usually this is the femoral artery which is both relatively large and relatively superficial, and easy to close on completion of the procedure using either direct compression or one of a variety of vessel closure devices. For this reason, endovascular devices are specifically designed for this femoral access site. However, the femoral artery and its vicinity are sometimes diseased, making it difficult or impossible to safely access or introduce a device into the vasculature from this site. In addition, the treatment target site may be quite some distance from the femoral access point requiring devices to be quite lengthy and cumbersome. Further, reaching the target site from the femoral access point may involve traversing tortuous and/or diseased arteries, which adds time and risk to the procedure. For these reasons, alternate access sites are sometimes employed. These include the radial, brachial and axillary arteries. However, these access sites are not always ideal, as they involve smaller arteries and may also include tortuous segments and some distance between the access and target sites.

In some instances, a desired access site is the carotid artery. For example, procedures to treat disease at the carotid artery bifurcation and internal carotid artery are quite close to this access site. Procedures in the intracranial and cerebral arteries are likewise much closer to this access site than the femoral artery. This artery is also larger than some of the alternate access arteries noted above. (The common carotid artery is typically <NUM> to <NUM> in diameter, the radial artery is <NUM> to <NUM> in diameter.

Because most access devices used in interventional procedure are designed for the femoral access, these devices are not ideal for the alternate carotid access sites, both in length and mechanical properties. This makes the procedure more cumbersome and in some cases more risky if using devices designed for femoral access in a carotid access procedure. For example, in some procedures it is desirable to keep the distal tip of the access sheath below or away from the carotid bifurcation, for example in procedures involving placing a stent at the carotid bifurcation. For patients with a low bifurcation, a short neck, or a very deep carotid artery, the angle of entry of the sheath into the artery (relative to the longitudinal axis of the artery) is very acute with respect to the longitudinal axis of the artery, i.e. more perpendicular than parallel relative to the longitudinal axis of the artery. This acute angle increases the difficulty and risk in sheath insertion and in insertion of devices through the sheath. In these procedures, there is also risk of the sheath dislodgement as only a minimal length of sheath can be inserted. In femoral or radial access cases, the sheaths are typically inserted into the artery all the way to the hub of the sheath, making sheath position very secure and parallel to the artery, so that the issues with steep insertion angle and sheath dislodgement do not occur in femoral or radial access sites.

In other procedures, it is desirable to position the sheath tip up to and possibly including the petrous portion of the internal carotid artery, for example in procedures requiring access to cerebral vessels. Conventional interventional sheaths and sheath dilators are not flexible enough to be safely positioned at this site.

In addition, radiation exposure may be a problem for the hands of the operators for procedures utilizing a transcarotid access site, if the working areas are close to the access site.

Document <CIT>discloses a micropuncture access needle comprising a proximal hub coupled to an elongate shaft defining an inner lumen, an access guidewire sized to be received through the inner lumen of the micropuncture access needle, the guidewire comprising a distal tip and at least one depth indicator positioned on the access guidewire a distance away from the distal tip of the guidewire; and a microaccess cannula comprising an elongate body defining an inner lumen and a depth indicator formed on the elongate body.

What is needed is a system of devices that optimize ease and safety of arterial access directly into the common carotid artery. What is also needed is a system of devices which minimize radiation exposure to the operator. What are also needed are methods (not claimed according to the present invention) for safe and easy access into the carotid artery to perform peripheral and neurovascular interventional procedures. These objectives are obtained, according to the invention, by means of a micropuncture kit for direct access into a lumen of a surgically exposed vessel using direct visual guidance according to appended claim <NUM>.

Disclosed are also methods (not claimed according to the present invention) and devices that enable safe, rapid and relatively short and straight transcarotid access to the arterial vasculature to treat coronary, peripheral and neurovascular disease states. The devices and associated methods (not claimed) include transcarotid access devices, guide catheters, catheters, and guide wires specifically to reach a target anatomy via a transcarotid access site. Included in this disclosure are kits of various combinations of these devices to facilitate multiple types of transcarotid interventional procedures.

In one example, there is disclosed a system of devices for accessing a carotid artery via a direct puncture of the carotid arterial wall, comprising a sheath guide wire, an arterial access sheath and a sheath dilator, wherein the arterial access sheath and sheath dilator are sized and configured to be inserted in combination over the sheath guide wire directly into the common carotid artery, and wherein the sheath has an internal lumen and a proximal port such that the lumen provides a passageway for an interventional device to be inserted via the proximal port into the carotid artery.

In another example, the system for accessing a carotid artery also includes: an access needle, an access guide wire, and an access cannula, all sized and configured to insert a sheath guide wire through the wall of the carotid artery so that the arterial access sheath and dilator may be placed into the carotid artery either percutaneously or via a surgical cut down.

In another example, there is disclosed a method (not claimed according to the present invention) for treatment of coronary, peripheral or neurovascular disease, comprising: forming a penetration in a wall of a carotid artery; positioning an arterial access sheath through the penetration into the artery; and treating a target site using a treatment device.

In another example, there is disclosed an arterial access sheath for introducing an interventional device into an artery. The arterial access sheath includes an elongated body sized and shaped to be transcervically introduced into a common carotid artery at an access location in the neck and an internal lumen in the elongated body having a proximal opening in a proximal region of the elongated body and a distal opening in a distal region of the elongated body. The internal lumen provides a passageway for introducing an interventional device into the common carotid artery when the elongated body is positioned in the common carotid artery. The elongated body has a proximal section and a distalmost section that is more flexible than the proximal section. A ratio of an entire length of the distalmost section to an overall length of the sheath body is one tenth to one half the overall length of the sheath body.

In an aspect, there is disclosed a micropuncture kit for direct access into a lumen of a surgically exposed vessel using direct visual guidance. The kit includes a micropuncture access needle having a proximal hub coupled to an elongate shaft defining an inner lumen and a visible depth indicator positioned on the elongate shaft a distance away from a distal tip of the elongate shaft. The kit includes an access guidewire sized to be received through the inner lumen of the micropuncture access needle. The guidewire includes a distal tip and at least one visible depth indicator positioned on the access guidewire a distance away from the distal tip of the guidewire. The kit includes a microaccess cannula having an elongate body defining an inner lumen and a plurality of visible depth indicators formed on the elongate body, wherein each of the plurality of visible depth indicators identifies a distance from a distal tip of the cannula.

The access guidewire can include a distalmost flexible section including the distal tip of the guidewire, a transition section proximal to the distalmost flexible section, and a stiffer core section extending proximally from the transition section. The distalmost flexible section can be between <NUM> and <NUM>, and the transition section can be between <NUM> and <NUM>. The transition section and the core section can be configured to support the microaccess cannula inserted into the vessel. The guidewire can be in a range of <NUM> to <NUM> (<NUM>" to <NUM>") outer diameter and the micropuncture needle can be in a range from <NUM> to <NUM> (<NUM> to <NUM>). The at least one visible depth indicator positioned on the access guidewire can have a proximal edge, a distal edge and a width extending between the proximal edge and the distal edge. The distance away from the distal tip of the guidewire can be measured from the distal tip to the distal edge of the at least one visible depth indicator. Inserting the access guidewire through the inner lumen of the elongate shaft until the distal edge is aligned with a back end of the proximal hub of the access needle can extend the distal tip of the guidewire beyond the distal tip of the elongate shaft an extension length. Advancing the access guidewire through the inner lumen of the elongate shaft until the proximal edge is aligned with the back end of the proximal hub of the access needle can extend the distal tip of the guidewire beyond the distal tip of the elongate shaft the extension length plus the width of the at least one visible depth indicator. The extension length can be <NUM> and the width of the at least one visible depth indicator can be <NUM>. The visible depth indicator of the access needle can be a chemical-etched marker, a laser-etched marker, or a pad printed marker. Each of the plurality of visible depth indicators can be formed by a number of marks. The number of marks can identify a number of increments from the distal tip of the cannula. Each increment can be <NUM> and the number of marks can be at least one mark. A first of the plurality of visible depth indicators on the cannula can include one mark and the first visible depth indicator can be <NUM> away from the distal tip of the cannula. A second of the plurality of visible depth indicators on the cannula can be two marks and the second visible depth indicator can be <NUM> away from the distal tip of the cannula. A third of the plurality of visible depth indicators on the cannula can be three marks and the third visible depth indicator can be <NUM> away from the distal tip of the cannula. A fourth of the plurality of visible depth indicators on the cannula can be four marks and the fourth visible depth indicator can be <NUM> away from the distal tip of the cannula. A fifth of the plurality of visible depth indicators on the cannula can be <NUM> away from the distal tip of the cannula and can be a solid band having a width that is greater than a width of one mark. The distance the visible depth indicator of the access needle is from the distal tip of the elongate shaft can be between <NUM> and <NUM>. The visible depth indicator of the access needle can be a chemical-etched marker, a laser-etched marker, or a pad printed marker.

Other features and advantages should be apparent from the following description of various embodiments, which illustrate, by way of example, the principles of the invention.

Disclosed are methods (not claimed according to the present invention), systems, and devices for accessing and treating the vasculature via a transcarotid access point in the region of the carotid artery.

<FIG> shows a first embodiment of a transcarotid initial access system <NUM> of devices for establishing initial access to a carotid artery for the purpose of enabling introduction of a guide wire into the carotid artery. The access to the carotid artery occurs at an access site located in the neck of a patient such as in the region of the patient's carotid artery. The devices of the transcarotid initial access system <NUM> are particularly suited for directly accessing the carotid artery through the wall of the common carotid artery.

As shown in <FIG>, the transcarotid initial access system <NUM> includes an access needle <NUM>, access guidewire <NUM>, and micropuncture cannula <NUM>. The access needle <NUM>, access guidewire <NUM>, and micropuncture cannula <NUM> are all adapted to be introduced via a carotid puncture into the carotid artery as further described below. The carotid puncture may be accomplished, for example, percutaneously or via a surgical cut down. Embodiments of the initial access system <NUM> may be adapted towards one or the other method of puncture, as further described below.

Upon establishment of access to the carotid artery using the initial access system <NUM>, an access sheath may be inserted into the carotid artery at the access site wherein the access sheath may be part of a transcarotid access sheath system. <FIG> shows a first embodiment of a transcarotid access sheath system <NUM> of devices for inserting an access sheath into the carotid artery over a sheath guidewire. When inserted into the carotid artery, the access sheath enables or allows introduction of at least one interventional device into the carotid artery via a lumen of the access sheath for the purpose of performing an interventional procedure on a region of the vasculature. The transcarotid access sheath system <NUM> includes an access sheath <NUM>, a sheath dilator <NUM>, and a sheath guidewire <NUM>. The access sheath <NUM>, sheath dilator <NUM> and sheath guidewire <NUM> are all adapted to be introduced via a carotid puncture into the carotid artery as further described below. The carotid puncture may be accomplished percutaneously or via a surgical cut down. Embodiments of the system <NUM> may be adapted towards one or the other method of puncture, as further described below.

In an embodiment, some or all of the components of transcarotid initial access system <NUM> and the transcarotid access sheath system <NUM> may be combined into one transcarotid access system kit such as by combining the components into a single, package, container or a collection of containers that are bundled together.

<FIG> shows the access sheath <NUM> being used to access a common carotid artery <NUM> for a carotid stenting procedure. The access sheath <NUM> is inserted into the common carotid artery <NUM> via a surgical cut down <NUM>. As described further below, the access sheath <NUM> has an internal lumen with openings at proximal and distal tips or regions of the access sheath <NUM>. With a distal portion of the access sheath <NUM> in the carotid artery and a proximal portion external to the patient, the internal lumen provides a passageway to insert an interventional device into the artery.

<FIG> shows an access sheath <NUM> of the transcarotid access system being used to access an internal carotid artery <NUM> for an intracranial or neurovascular procedure. The arterial access sheath <NUM> accesses the common carotid artery <NUM> via insertion through a transcervical puncture. Once inserted into the common carotid artery <NUM>, the distal tip of the access sheath <NUM> is advanced into the internal carotid artery ICA <NUM> and upward (relative to the puncture in <FIG>) toward distal cervical or petrous ICA <NUM> or beyond.

<FIG> and <FIG> both show the arterial access sheath <NUM> being advanced upward through the patient's neck toward the patient's brain. In another embodiment, the arterial access sheath <NUM> may be advanced downward (relative to access locations in <FIG>) toward the patient's heart such as toward the aorta for example. <CIT> entitled "Systems and Methods for Transcatheter Aortic Valve Treatment" describes exemplary methods of directly inserting an access sheath into the carotid artery and advancing an interventional device toward the aorta and ultimately towards the aortic valve.

With reference again to <FIG>, an embodiment of a transcarotid arterial access sheath <NUM> includes an elongated sheath body <NUM> and a proximal adaptor <NUM> at a proximal end of the elongated sheath body <NUM> of the access sheath <NUM>. The elongated sheath body <NUM> is the portion of the arterial access sheath <NUM> that is sized and shaped to be inserted into the artery and wherein at least a portion of the elongated sheath body is actually inserted into the artery during a procedure. The proximal adaptor <NUM> includes a hemostasis valve <NUM> and an elongated flush line <NUM> having an internal lumen that communicates with an internal lumen of the sheath body <NUM>. The proximal adaptor <NUM> may have a larger diameter or cross-sectional dimension than the sheath body <NUM>. The hemostasis valve <NUM> communicates with the internal lumen of the sheath body <NUM> to allow introduction of devices therein while preventing or minimizing blood loss via the internal lumen during the procedure. In an embodiment, the hemostasis valve <NUM> is a static seal-type passive valve. In an alternate embodiment of the arterial access sheath <NUM> (shown in <FIG>) the hemostasis valve <NUM> is an adjustable-opening valve such as a Tuohy-Borst valve <NUM> or rotating hemostasis valve (RHV). Alternately, the access sheath <NUM> may terminate on the proximal end in a female Luer adaptor to which a separate hemostasis valve component may be attached, either a passive seal valve, a Tuohy-Borst valve or rotating hemostasis valve (RHV).

The elongated sheath body <NUM> of the arterial access sheath <NUM> has a diameter that is suitable or particularly optimized to provide arterial access to the carotid artery. In an embodiment, the elongated sheath body <NUM> is in a size range from <NUM> to <NUM> French, or alternately in an inner diameter range from <NUM> to <NUM> (<NUM> inches to <NUM> inches). In an embodiment, the elongated sheath body <NUM> is a <NUM> or <NUM> French sheath. In an embodiment where the sheath is also used for aspiration or reverse flow, or to introduce larger devices, the sheath is an <NUM> French sheath.

The elongated sheath body <NUM> of the arterial access sheath <NUM> has a length from the proximal adapter <NUM> to a distal tip of the elongated sheath body <NUM> that is suitable for reaching treatment sites located in or toward the brain relative to an arterial access site in the common carotid artery CCA. For example, to access a carotid artery bifurcation or proximal internal carotid artery ICA from a CCA access site, the elongated sheath body <NUM> (i.e., the portion that can be inserted into the artery) of the access sheath <NUM> may have a length in a range from <NUM> to <NUM>. In an embodiment, the elongated sheath body <NUM> has a length in the range of <NUM>-<NUM>. For access to a same target site from a femoral access site, typical access sheaths must be between <NUM> and <NUM>, or a guide catheter must be inserted through an arterial access sheath and advanced to the target site. A guide catheter through an access sheath takes up luminal area and thus restricts the size of devices that may be introduced to the target site. Thus an access sheath that allows interventional devices to reach a target site without a guide catheter has advantages over an access sheath that requires use of a guide catheter to allow interventional devices to the target site.

Alternately, to position the distal tip of the elongated sheath body <NUM> more distally relative to the access site, for example to perform an intracranial or neurovascular procedure from a CCA access site, the elongated sheath body <NUM> of the access sheath <NUM> may have a length in the range from <NUM> to <NUM>, depending on the desired target position of the sheath distal tip. For example, if the target position is the distal CCA or proximal ICA, the elongated sheath body <NUM> may be in the range from <NUM> to <NUM>. If the desired target position is the mid to distal cervical, petrous, or cavernous segments of the ICA, the elongated sheath body <NUM> may be in the range from <NUM> to <NUM>.

Alternately, the arterial access sheath <NUM> is configured or adapted for treatment sites or target locations located proximal to the arterial access site (i.e. towards the aorta) when the access site is in the common carotid artery. For example the treatment site may be the proximal region of the CCA, CCA ostium, ascending or descending aorta or aortic arch, aortic valve, coronary arteries, or other peripheral arteries. For these target locations, the appropriate length of the elongated sheath body <NUM> depends on the distance from the target location to the access site. In this configuration, the elongated sheath body <NUM> is placed through an arterial access site and directed inferiorly towards the aorta.

The access sheath <NUM> may also include a radiopaque tip marker <NUM>. In an example the radiopaque tip marker is a metal band, for example platinum iridium alloy, embedded near the distal end of the sheath body <NUM> of the access sheath <NUM>. Alternately, the access sheath tip material may be a separate radiopaque material, for example a barium polymer or tungsten polymer blend. The sheath tip itself is configured such that when the access sheath <NUM> is assembled with the sheath dilator <NUM> to form a sheath assembly, the sheath assembly can be inserted smoothly over the sheath guide wire <NUM> through the arterial puncture with minimal resistance. In an embodiment, the elongated sheath body <NUM> of the access sheath <NUM> has a lubricious or hydrophilic coating to reduce friction during insertion into the artery. In an embodiment, the distal coating is limited to the distalmost <NUM> to <NUM> of the elongated sheath body <NUM>, so that it facilitates insertion without compromising security of the sheath in the puncture site or the ability of the operator to firmly grasp the sheath during insertion. In an alternate embodiment, the sheath has no coating.

With reference to <FIG>, in an embodiment, the arterial access sheath <NUM> has features to aid in securement of the sheath during the procedure. For example the access sheath <NUM> may have a suture eyelet <NUM> or one or more ribs <NUM> molded into or otherwise attached to the adaptor <NUM> (located at the proximal end of the elongated sheath body <NUM>) which would allow the operator to suture tie the sheath hub to the patient.

For a sheath adapted to be inserted into the common carotid artery for the purpose of access to the carotid bifurcation, the length of the elongated sheath body <NUM> can be in the range from <NUM> to <NUM>, usually being from <NUM> to <NUM>. The inner diameter is typically in the range from <NUM> Fr (<NUM> Fr = <NUM>), to <NUM> Fr, usually being <NUM> to <NUM> Fr. For a sheath adapted to be inserted via the common carotid artery to the mid or distal internal carotid artery for the purpose of access to the intracranial or cerebral vessels, the length of the elongated sheath body <NUM> can be in the range from <NUM> to <NUM>, usually being from <NUM> to <NUM>. The inner diameter is typically in the range from <NUM> Fr (<NUM> Fr = <NUM>), to <NUM> Fr, usually being <NUM> to <NUM> Fr.

Particularly when the sheath is being introduced through the transcarotid approach, above the clavicle but below the carotid bifurcation, it is desirable that the elongated sheath body <NUM> be flexible while retaining hoop strength to resist kinking or buckling. This is especially important in procedures that have limited amount of sheath insertion into the artery, and there is a steep angle of insertion as with a transcarotid access in a patient with a deep carotid artery and/or with a short neck. In these instances, there is a tendency for the sheath body tip to be directed towards the back wall of the artery due to the stiffness of the sheath. This causes a risk of injury from insertion of the sheath body itself, or from devices being inserted through the sheath into the arteries, such as guide wires. Alternately, the distal region of the sheath body may be placed in a distal carotid artery which includes one or more bends, such as the petrous ICA. Thus, it is desirable to construct the sheath body <NUM> such that it can be flexed when inserted in the artery, while not kinking. In an embodiment, the sheath body <NUM> is circumferentially reinforced, such as by stainless steel or nitinol braid, helical ribbon, helical wire, cut stainless steel or nitinol hypotube, cut rigid polymer, or the like, and an inner liner so that the reinforcement structure is sandwiched between an 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 of a group of materials including Pebax, thermoplastic polyurethane, or nylon.

In an embodiment, the sheath body <NUM> may vary in flexibility over its length. This change in flexibility may be achieved by various methods. For example, the outer jacket may change in durometer and/or material at various sections. Alternately, the reinforcement structure or the materials may change over the length of the sheath body. In one embodiment, there is a distalmost section of sheath body <NUM> which is more flexible than the remainder of the sheath body. For example, the flexural stiffness of the distalmost section is one third to one tenth the flexural stiffness of the remainder of the sheath body <NUM>. In an embodiment, the distalmost section has a flexural stiffness (E*I) in the range <NUM> to <NUM> N-mm<NUM> and the remaining portion of the sheath body <NUM> has a flexural stiffness in the range <NUM> to <NUM> N-mm<NUM> , where E is the elastic modulus and I is the area moment of inertia of the device. For a sheath configured for a CCA access site, the flexible, distal most section comprises a significant portion of the sheath body <NUM> which may be expressed as a ratio. In an embodiment, the ratio of length of the flexible, distalmost section to the overall length of the sheath body <NUM> is at least one tenth and at most one half the length of the entire sheath body <NUM>.

In some instances, the arterial access sheath is configured to access a carotid artery bifurcation or proximal internal carotid artery ICA from a CCA access site. In this instance, an embodiment of the sheath body <NUM> has a distalmost section <NUM> which is <NUM> to <NUM> and the overall sheath body <NUM> is <NUM> to <NUM>. In this embodiment, the ratio of length of the flexible, distalmost section to the overall length of the sheath body <NUM> is about one forth to one half the overall length of the sheath body <NUM>. In another embodiment, there is a transition section <NUM> between the distalmost flexible section and the proximal section <NUM>, with one or more sections of varying flexibilities between the distalmost section and the remainder of the sheath body. In this embodiment, the distalmost section is <NUM> to <NUM>, the transition section is <NUM> to <NUM> and the overall sheath body <NUM> is <NUM> to <NUM>, or expressed as a ratio, the distalmost flexible section and the transition section collectively form at least one fourth and at most one half the entire length of the sheath body.

In some instances, the sheath body <NUM> of the arterial access sheath is configured to be inserted more distally into the internal carotid artery relative to the arterial access location, and possibly into the intracranial section of the internal carotid artery. For example, a distalmost section <NUM> of the elongated sheath body <NUM> is <NUM> to <NUM> and the overall sheath body <NUM> is <NUM> to <NUM> in length. In this embodiment, the ratio of length of the flexible, distalmost section to the overall length of the sheath body is one tenth to one quarter of the entire sheath body <NUM>. In another embodiment, there is a transition section <NUM> between the distalmost flexible section and the proximal section <NUM>, in which the distalmost section is <NUM> to <NUM>, the transition section is <NUM> to <NUM> and the overall sheath body <NUM> is <NUM> to <NUM>. In this embodiment, the distalmost flexible section and the transition section collectively form at least one sixth and at most one half the entire length of the sheath body.

Other embodiments are adapted to reduce, minimize or eliminate a risk of injury to the artery caused by the distal-most sheath tip facing and contacting the posterior arterial wall. In some embodiments, the sheath has a structure configured to center the sheath body tip in the lumen of the artery such that the longitudinal axis of the distal region of the sheath body is generally parallel with the longitudinal or center axis of the lumen of the vessel. In an embodiment shown in <FIG>, the sheath alignment feature is an inflatable or enlargeable bumper, for example a balloon <NUM>, located on an outer wall of the arterial access sheath <NUM>. The balloon <NUM> may be increased in size to exert a force on inner the arterial that contacts and pushes the elongated body <NUM> of the aerial access sheath away from the arterial wall.

In another embodiment, the sheath alignment feature is one or more mechanical structures on the sheath body that can be actuated to extend outward from the sheath tip. In an embodiment, the sheath body <NUM> is configured to be inserted into the artery such that a particular edge of the arterial access is against the posterior wall of the artery. In this embodiment, the sheath alignment feature need only extend outward from one direction relative to the longitudinal axis of the sheath body <NUM> to lift or push the sheath tip away from the posterior arterial wall. For example, as shown in <FIG>, the inflatable bumper <NUM> is a blister on one side of the sheath body. In another example, the mechanical feature extends only on one side of the sheath body.

In another embodiment, at least a portion of the sheath body <NUM> is pre-shaped so that after sheath insertion the tip is more aligned with the long axis of the vessel, even at a steep sheath insertion angle. In this embodiment the sheath body is generally straight when the dilator is assembled with the sheath during sheath insertion over the sheath guide wire, but once the dilator and guidewire are removed, the distalmost section of the sheath body assumes a curved or angled shape. In an embodiment, the sheath body is shaped such that the distalmost <NUM> to <NUM> section is angled from <NUM> to <NUM> degrees, as measured from the main axis of the sheath body, with a radius of curvature about <NUM> (<NUM>"). To retain the curved or angled shape of the sheath body after having been straightened during insertion, the sheath may be heat set in the angled or curved shape during manufacture. Alternately, the reinforcement structure may be constructed out of nitinol and heat shaped into the curved or angled shape during manufacture. Alternately, an additional spring element may be added to the sheath body, for example a strip of spring steel or nitinol, with the correct shape, added to the reinforcement layer of the sheath.

In an alternate embodiment, there are procedures in which it is desirable to minimize flow resistance through the access sheath such as described in <CIT>and <CIT>. <FIG> shows such an embodiment of the sheath body <NUM> where the sheath body has stepped or tapered configuration having a reduced diameter distal region <NUM> (with the reduced diameter being relative to the remainder of the sheath). The distal region <NUM> of the stepped sheath can be sized for insertion into the carotid artery, typically having an inner diameter in the range from <NUM> to <NUM> (<NUM> inch to <NUM> inch) with the remaining proximal region of the sheath having larger outside and luminal diameters, with the inner diameter typically being in the range from <NUM> to <NUM> (<NUM> inch to <NUM> inch). The larger luminal diameter of the remainder of the sheath body minimizes the overall flow resistance through the sheath. In an embodiment, the reduced-diameter distal section <NUM> has a length of approximately <NUM> to <NUM>. The relatively short length of the reduced-diameter distal section <NUM> permits this section to be positioned in the common carotid artery CCA via a transcarotid approach with reduced risk that the distal end of the sheath body will contact the bifurcation B. Moreover, the reduced diameter section also permits a reduction in size of the arteriotomy for introducing the sheath into the artery while having a minimal impact in the level of flow resistance. Further, the reduced distal diameter section may be more flexible and thus more conformal to the lumen of the vessel.

In some instances it is desirable for the sheath body <NUM> to also be able to occlude the artery in which it is positioned, for examples in procedures that may create distal emboli. In these cases, occluding the artery stops antegrade blood flow in the artery and thereby reduces the risk of distal emboli that may lead to neurologic symptoms such as TIA or stroke. <FIG> shows an embodiment of an arterial access sheath <NUM> with an inflatable balloon <NUM> on a distal region that is inflated via an inflation line <NUM> that connects an internal inflation lumen in the sheath body <NUM> to a stopcock <NUM> which in turn may be connected to an inflation device. In this embodiment, there is also a Y-arm <NUM> that may be connected to a passive or active aspiration source to further reduce the risk of distal emboli.

In some instances it is desirable to move the hemostasis valve away from the distal tip of the sheath, while maintaining the length of the insertable sheath body <NUM> of the sheath. This embodiment is configured to move the hands of the operator, and in fact his or her entire body, away from the target site and therefore from the image intensifier that is used to image the target site fluoroscopically, thus reducing the radiation exposure to the user during the procedure. Essentially, this lengthens the portion of the arterial access sheath <NUM> that is outside the body. This portion can be a larger inner and outer diameter than the sheath body <NUM>. In instances where the outer diameter of the catheter being inserted into the sheath is close to the inner diameter of the sheath body, the annular space of the lumen that is available for flow is restrictive. Minimizing the sheath body length is thus advantageous to minimize this resistance to flow, such as during flushing of the sheath with saline or contrast solution, or during aspiration or reverse flow out of the sheath. In an embodiment, as shown in <FIG>, the arterial access sheath <NUM> has an insertable, elongated sheath body <NUM> (i.e. the portion configured to insert into the artery) and a proximal extension portion <NUM>. In an embodiment, the sheath body <NUM> has an inner diameter of about <NUM> (<NUM>") and an outer diameter of about <NUM> (. <NUM>"), corresponding to a <NUM> French sheath size, and the proximal extension has an inner diameter of about <NUM> to <NUM> (. <NUM>") and an outer diameter of about <NUM> to <NUM> (. In another embodiment, the sheath body <NUM> has an inner diameter of about <NUM> (. <NUM>") and an outer diameter of about <NUM> (. <NUM>"), corresponding to an <NUM> French sheath size, and the proximal extension has an inner diameter of about <NUM> (. <NUM>") and an outer diameter of about <NUM> (. In yet another embodiment, the sheath body <NUM> is stepped with a smaller diameter distal section <NUM> to further reduce flow restriction, as in <FIG>. In an embodiment, the proximal extension <NUM> is a length suitable to meaningfully reduce the radiation exposure to the user during a transcarotid access procedure. For example, the proximal extension <NUM> is between <NUM> and <NUM>, or between <NUM> and <NUM>. Alternately, the proximal extension <NUM> has a length configured to provide a distance of between about <NUM> and <NUM> between the hemostasis valve <NUM> and the distal tip of the sheath body, depending on the insertable length of the access sheath. A connector structure <NUM> can connect the elongated sheath body <NUM> to the proximal extension <NUM>. In this embodiment, the connector structure <NUM> may include a suture eyelet <NUM> and/or ribs <NUM> to assist in securing the access sheath to the patient. In an embodiment, the hemostasis valve <NUM> is a static seal-type passive valve. In an alternate embodiment the hemostasis valve <NUM> is an adjustable-opening valve such as a Tuohy-Borst valve <NUM> or rotating hemostasis valve (RHV). Alternately, the proximal extension may terminate on the proximal end in a female Luer adaptor to which a separate hemostasis valve component may be attached, either a passive seal valve, a Tuohy-Borst valve or rotating hemostasis valve (RHV).

Typically, vessel closure devices require an arterial access sheath with a maximum distance of about <NUM> between distal tip of the sheath body to the proximal aspect of the hemostasis valve, with sheath body <NUM> of about <NUM> and the remaining <NUM> comprising the length of the proximal hemostasis valve; thus if the access sheath has a distance of greater than <NUM> it is desirable to remove the proximal extension <NUM> at the end of the procedure. In an embodiment, the proximal extension <NUM> is removable in such a way that after removal, hemostasis is maintained. For example a hemostasis valve is built into the connector <NUM> between the sheath body <NUM> and the proximal extension <NUM>. The hemostasis valve is opened when the proximal extension <NUM> is attached to allow fluid communication and insertion of devices, but prevents blood flowing out of the sheath when the proximal extension <NUM> is removed. After the procedure is completed, the proximal extension <NUM> can be removed, reducing the distance between the proximal aspect of the hemostasis valve and sheath tip from greater than <NUM> to equal or less than <NUM> and thus allowing a vessel closure device to be used with the access sheath <NUM> to close the access site.

In some procedures it may be desirable to have a low resistance (large bore) flow line or shunt connected to the access sheath, such as described in <CIT>and <CIT>. The arterial sheath embodiment shown in <FIG> has a flow line <NUM> with internal lumen to a Y-arm <NUM> of the connector <NUM>. This flow line has a lumen fluidly connected to a lumen in the sheath body. The flow line <NUM> may be connected to a lower pressure return site such as a venous return site or a reservoir. The flow line <NUM> may also be connected to an aspiration source such as a pump or a syringe. In an embodiment, an occlusion element may also be included on the distal end of the sheath body <NUM>, for example an occlusion balloon. This may be desirable in percutaneous procedures, where the vessel cannot be occluded by vascular surgical means such as vessel loops or vascular clamps.

In some procedures, it may be desirable to limit the amount of sheath body insertion into the artery, for example in procedures where the target area is very close to the arterial access site. In a stent procedure of the carotid artery bifurcation, for example, the sheath tip should be positioned proximal of the treatment site (relative to the access location) so that it does not interfere with stent deployment or enter the diseased area and possibly cause emboli to get knocked loose. In an embodiment of arterial sheath <NUM> shown in <FIG>, a sheath stopper <NUM> is slidably connected or mounted over the outside of the distal portion of the sheath body (see also <FIG>). The sheath stopper <NUM> is shorter than the distal portion of the sheath, effectively shortening the insertable portion of the sheath body <NUM> by creating a positive stop at a certain length along the sheath body <NUM>. The sheath stopper <NUM> may be a tube that slidably fits over the sheath body <NUM> with a length that, when positioned on the sheath body <NUM>, leaves a distal portion of the sheath body exposed. This length can be in the range <NUM> to <NUM>. More particularly, the length is <NUM>. The distal end of the sheath stopper <NUM> may be angled and oriented such that the angle sits flush with the vessel and serves as a stop against the arterial wall when the sheath is inserted into the artery when the vessel is inserted into the artery, as shown in <FIG>. Alternately, the distal end of the sheath stopper may be formed into an angled flange <NUM> that contacts the arterial wall, as shown in <FIG>, <FIG>. The flange <NUM> is rounded or has an atraumatic shape to create a more positive and atraumatic stop against the arterial wall. The sheath stopper <NUM> may be permanently secured to the arterial sheath, for example the proximal end of the sheath stopper may be adhered to connector <NUM> of the arterial access sheath. Alternately, the sheath stopper <NUM> may be removable from the arterial access sheath <NUM> by the user so it can be optionally utilized in a procedure. In this instance, the sheath stopper <NUM> may have a locking feature <NUM> on the proximal portion that engages with a corresponding locking features on the connector <NUM>, for example slots or recesses on the proximal sheath stopper engaging protrusions on the connector. Other locking features may also be utilized.

Again with respect to <FIG>, the sheath stopper <NUM> can include one or more cutouts, indents, or recessed grooves 1120a or other features along a length of the sheath stopper <NUM>, for example along the anterior surface of the sheath stopper <NUM>. The grooves 1120a can be sized to receive sutures used to secure the sheath <NUM> to the patient to improve sheath stability and mitigate against sheath dislodgement. The one or more recessed grooves 1120a on the sheath stopper <NUM> can extend along an arc around the longitudinal axis of the sheath stopper <NUM>. The one or more recessed grooves 1120a on the anterior surface can alternate or be in a staggered pattern with corresponding one or more recessed grooves 1120b on the posterior surface of the sheath stopper <NUM> to provide additional flexibility to the sheath assembly in the anterior-to-posterior plane while maintaining axial strength to allow forward force of the sheath stopper against the arterial wall. Increased flexibility of the sheath assembly can reduce the amount of stress that may be placed on a vessel. In some implementations, a visual indicator <NUM> can be positioned on the anterior surface of the sheath stopper <NUM>. The visual indicator <NUM> can be pad-printed text, line, or other pattern. The visual indicator <NUM> can be molded directly into the body of the sheath stopper <NUM>. The indicator <NUM> can provide an external visual reference for rotational orientation of the sheath stopper (and thereby orientation of the distal flange <NUM>) with respect to the vessel. In use, the indicator <NUM> can face anteriorly with respect to the patient. Using this orientation, the distal flange <NUM> can lie approximately flat against the anterior wall of the vessel, e.g. the common carotid artery. Additional features the sheath stopper <NUM> may incorporate are described in <CIT>.

As mentioned above, the access sheath <NUM> may include a radiopaque tip marker <NUM>. The access sheath <NUM> can also incorporate one or more markers <NUM> positioned on the sheath body <NUM> (see <FIG>) providing external visual guidance during insertion of the sheath <NUM> without special imaging to assess depth of insertion, as will be described in more detail below. In some implementations, the markers <NUM> can be pad printed markers that designate insertion depths in increments of <NUM> up to about <NUM>. The external visual reference markers <NUM> on the sheath body <NUM> can supplement the radiopaque tip marker <NUM> and the physical depth limit provided by the sheath stopper <NUM>. The external visual reference markers <NUM> can be useful, for example, when a user wants to insert the sheath <NUM> to a shallower depth than prescribed by the sheath stopper <NUM> or when a user removes the sheath stopper <NUM> from the sheath body <NUM>.

In situations where the insertion of the sheath body is limited to between <NUM> and <NUM>, and particularly when the sheath body is inserted at a steep angle, the sheath may conform to a bayonet shape when secured to the patient. For example, the bayonet shape may comprise a first portion that extends along a first axis and a second portion that extends along a second axis that is axially offset from the first axis and/or non-parallel to the first axis. The springiness of the sheath body causes this shape to exert a force on the vessel at the site of insertion and increase the tendency of the sheath to come out of the vessel if not properly secured. To reduce the stress on the vessel, the sheath stopper may be pre-shaped into a curved or bayonet shape so that the stress of the sheath body when curved is imparted onto the sheath stopper rather than on the vessel. The sheath stopper may be made from springy but bendable material or include a spring element such as a stainless steel or nitinol wire or strip, so that when the dilator is inserted into the sheath and sheath stopper assembly, the sheath is relatively straight, but when the dilator is removed the sheath stopper assumes the pre-curved shape to reduce the force the sheath imparts on the vessel wall. Alternately, the sheath stopper may be made of malleable material or include a malleable element such as a bendable metal wire or strip, so that it can be shaped after the sheath is inserted into a desired curvature, again to reduce the stress the sheath imparts on the vessel wall.

With reference again to <FIG>, the sheath dilator <NUM> is a component of the transcarotid access sheath system <NUM>. The sheath dilator <NUM> is an elongated body that is inserted into the artery and enables smooth insertion of the access sheath <NUM> over the sheath guidewire <NUM> through a puncture site in the arterial wall. Thus, the distal end of the dilator <NUM> is generally tapered to allow the dilator to be inserted over the sheath guidewire <NUM> into the artery, and to dilate the needle puncture site to a larger diameter for insertion of the access sheath <NUM> itself. To accommodate these functions, the dilator <NUM> has a tapered end <NUM> with a taper that is generally between <NUM> and <NUM> degrees total included angle (relative to a longitudinal axis of the dilator), with a radiused leading edge. Sheath dilators are typically locked to the access sheath when assembled for insertion into the artery. For example a proximal hub <NUM> of the sheath dilator <NUM> is structured to snap into or over a corresponding structure on the hemostasis valve <NUM> of the arterial access sheath <NUM>. An inner lumen of the dilator <NUM> accommodates a sheath guidewire <NUM>, with an inner diameter of between <NUM> to <NUM> (. <NUM>"), depending on the sheath guide wire size for example.

For a transcarotid access sheath system <NUM>, it may be desirable to make the distal section of the sheath dilator <NUM> more flexible, to correspond with an increased flexible section of the access sheath <NUM>. For example, the distal <NUM> to <NUM> of the sheath dilator <NUM> may be <NUM>% to <NUM>% more flexible than the proximal portion of the sheath dilator <NUM>. This embodiment would allow a sheath and dilator being inserted to accommodate a steep insertion angle, as is often the case in a transcarotid access procedure, with a smoother insertion over the guidewire while still maintaining columnar support of the dilator. The columnar support is desirable to provide the insertion force required to dilate the puncture site and insert the access sheath.

For some transcarotid access sheath systems, it may be desirable to also use a smaller diameter access guidewire (for example in the range <NUM> to <NUM> (. <NUM>" diameter)) to guide the sheath and dilator into the artery. In this embodiment, the sheath dilator tapered end <NUM> is configured to provide a smooth transition from a smaller wire size to the access sheath. In one variation, the sheath guide wire is <NUM> (. <NUM>") and the inner dilator lumen is in the range <NUM> to <NUM> (. In another variation, the sheath guide wire is <NUM> (. <NUM>") and the inner dilator lumen is in the range <NUM> to <NUM> (. The taper is similarly modified, for example the taper length is longer to accommodate a taper from a smaller diameter to the inner diameter of the access sheath, or may comprise two taper angles to provide a smooth transition from the smaller diameter wire to the access sheath without overly lengthening the overall length of the taper.

In some procedures, it is desirable to position the distal tip of the sheath body <NUM> of the arterial access sheath <NUM> in the mid to distal cervical, petrous, or cavernous segments of the ICA as described above. These segments have curvature often greater than <NUM> degrees. In may be desirable to have a sheath dilator with a softer and longer taper, to be able to navigate these bends easily without risk of injury to the arteries. However, in order to insert the sheath through the arterial puncture, the dilator desirably has a certain stiffness and taper to provide the dilating force. In an embodiment, the transcarotid access sheath system <NUM> is supplied or included in a kit that includes two or more tapered dilators 260A and 260B. The first tapered dilator 260A is used with the arterial access device to gain entry into the artery, and is thus sized and constructed in a manner similar to standard introducer sheath dilators. Example materials that may be used for the tapered dilator include, for example, high density polyethylene, 72D Pebax, 90D Pebax, or equivalent stiffness and lubricity material. A second tapered dilator 260B of the kit may be supplied with the arterial access device with a softer distal section or a distal section that has a lower bending stiffness relative to the distal section of the first tapered dilator. That is, the second dilator has a distal region that is softer, more flexible, or articulates or bends more easily than a corresponding distal region of the first dilator. The distal region of the second dilator thus bends more easily than the corresponding distal region of the first dilator. In an embodiment, the distal section of the first dilator 260A has a bending stiffness in the range of <NUM> to <NUM> N-mm<NUM> and the distal section of the second dilator 260B has a bending stiffness in the range of <NUM> to <NUM> N-mm<NUM>.

The second dilator 260B (which has a distal section with a lower bending stiffness) may be exchanged with the initial, first dilator such that the arterial access device may be inserted into the internal carotid artery and around curvature in the artery without undue force or trauma on the vessel due to the softer distal section of the second dilator. The distal section of the soft, second dilator may be, for example, <NUM> or 40D Pebax, with a proximal portion made of, for example 72D Pebax. An intermediate mid portion or portions may be included on the second dilator to provide a smooth transition between the soft distal section and the stiffer proximal section. In an embodiment, one or both dilators may have radiopaque tip markers so that the dilator tip position is visible on fluoroscopy. In one variation, the radiopaque marker is a section of tungsten loaded Pebax or polyurethane which is heat welded to the distal tip of the dilator. Other radiopaque materials may similarly be used to create a radiopaque marker at the distal tip.

To facilitate exchange of the first dilator for the second dilator, one or both dilators may be configured such that the distal section of the dilator is constructed from a tapered single-lumen tube, but the proximal portion of the dilator and any adaptor on the proximal end has a side opening. <FIG> shows an example of a dilator <NUM> formed of an elongated member sized and shaped to be inserted into an artery, and a proximal hub <NUM>. The dilator has a side opening <NUM>, such as a slot, that extends along at least a portion of the length of the dilator <NUM> such as along the elongated body and the proximal hub <NUM>. In an embodiment, the side opening <NUM> is located only on a proximal region of the dilator <NUM> and through the proximal hub <NUM> although this may vary. The side opening <NUM> provides access to an internal lumen of the dilator <NUM>, such as to insert and/or remove a guidewire into or from the lumen. An annular, movable sleeve <NUM> with a slot on one side is located at or near the proximal hub <NUM> of the dilator <NUM>. The sleeve <NUM> may be moved, such as via rotation, about a longitudinal axis of the hub <NUM>, as described below. Note that the distal end of the dilator <NUM> has a tapered configuration for dilating tissue.

<FIG> shows an enlarged view of the proximal region of the dilator <NUM>. As mentioned, the dilator <NUM> has a side opening <NUM> in the form of a slot that extends along the length of the dilator <NUM> and the proximal hub <NUM>. The sleeve <NUM> is positioned around the outer periphery of the dilator and is shaped such that it covers at least a portion of the side opening <NUM>. Thus, the sleeve <NUM> can prevent a guidewire positioned inside the dilator <NUM> from exiting the dilator via the side opening <NUM>. As mentioned, the sleeve <NUM> is rotatable relative to the dilator <NUM> and proximal hub <NUM>. In the illustrated embodiment, the sleeve <NUM> is rotatable about a longitudinal axis of the dilator <NUM> although other types of relative movement are within the scope of this disclosure. As shown in <FIG>, the sleeve <NUM> has a slot <NUM> that can be aligned with the side opening <NUM>. When aligned as such, the slot <NUM> and side opening <NUM> collectively provide an opening for a guidewire to be inserted or removed from the internal lumen of the dilator <NUM>. The sleeve <NUM> can be rotated between the position shown in <FIG> (where it covers the side opening <NUM>) and the position shown in <FIG> (where the side opening is uncovered due to the slot <NUM> being aligned with the side opening <NUM>.

A method of use of this embodiment of an access sheath kit is now described. A sheath guide wire, such as an <NUM>" guidewire, is inserted into the common carotid artery, either using a Modified Seldinger technique or a micropuncture technique. The distal end of the guidewire can be positioned into the internal or external carotid artery, or stop in the common carotid artery short of the bifurcation. The arterial access sheath with the first, stiffer dilator, is inserted over the <NUM> (. <NUM>") wire into the artery. The arterial access sheath is inserted such that at least <NUM> of sheath body <NUM> is in the artery. If additional purchase is desired, the arterial access sheath may be directed further, and into the internal carotid artery. The first dilator is removed while keeping both the arterial access sheath and the <NUM> (. <NUM>") wire in place. The side opening <NUM> in the proximal portion of the dilator allows the dilator to be removed in a "rapid exchange" fashion such that most of the guidewire outside the access device may be grasped directly during dilator removal. The second dilator is then loaded on to the <NUM> (. <NUM>") wire and inserted into the sheath. Again, a dilator with a side opening <NUM> in the proximal portion of the dilator may be used to allow the <NUM> (. <NUM>") wire to be grasped directly during guide wire insertion in a "rapid exchange" technique. Once the second dilator is fully inserted into the arterial access device, the arterial access sheath with the softer tipped, second dilator is advanced up the internal carotid artery and around bends in the artery without undue force or concern for vessel trauma. This configuration allows a more distal placement of the arterial access sheath without compromising the ability of the device to be inserted into the artery.

Alternately, one or more standard dilators may be used without side openings. If a standard dilator without a side opening is used, after the access device is inserted into the artery over a guide wire with the first dilator, the first dilator may be removed together with the guidewire, leaving only the access device in place. The second dilator with a guide wire preloaded into the central lumen may be inserted together into the arterial access device. Once fully inserted, the access device and second dilator with softer tip may be advanced distally up the internal carotid artery as above. In this alternate method, the initial guide wire may be used with both dilators, or may be exchanged for a softer tipped guide wire when inserted with the second softer tipped dilator.

In some instances, it may be desirable to insert the access sheath system over an <NUM> (. <NUM>") wire into the carotid artery, but then exchange the wire to a smaller guidewire, in the range <NUM> to <NUM> (. Because the access into the carotid artery may require a steep angle of entry, a wire that can offer good support such as an. <NUM>" wire may be desirable to initially introduce the access sheath into the CCA. However, once the sheath is in the artery but the user would like to advance it further over a smaller guidewire, it may be desirable to exchange the <NUM> (. <NUM>") wire for a smaller guide wire. Alternately, the user may exchange both the dilator and <NUM> (. <NUM>") wire for a softer dilator and smaller guide wire in the range <NUM> to <NUM> (. Alternately, the user may wish to position an <NUM> (. <NUM>") guidewire which he or she will subsequently use to introduce an interventional device, while the sheath and dilator are still in place. The dilator may offer access and support for this guide wire, and in instances of severe access sheath angle may aid in directing the wire away from the posterior wall of the artery so that the wire may be safely advanced into the vascular lumen without risk of luminal injury.

In an embodiment as shown in <FIG>, the sheath dilator <NUM> is a two-part dilator assembly, with an inner dilator <NUM> and an outer dilator <NUM> that slidably attach to one another in a co-axial arrangement. Both dilators have proximal hubs 264a and 264b. When the two dilators are assembled together, the two hubs 264a and 264b have features which allow them to be locked together, e.g. a snap fit or a threaded fit, so that the two dilators can be handled as one unit. In an embodiment, the inner dilator <NUM> has a proximal hub 264b which includes a rotating coupler with internal threads that engage external threads on the proximal hub 264a of the outer dilator <NUM>. The inner dilator <NUM> effectively transforms the dilator assembly from an <NUM> or <NUM> (. <NUM>") wire compatible dilator to an <NUM> or <NUM> (. <NUM>") wire compatible dilator, and extends out the distal end of the outer dilator. In an embodiment, shown in <FIG>, the inner dilator has an angled tip <NUM> that is bent or angled relative to a longitudinal axis of the remainder of the dilator. In an embodiment, the angle is a <NUM> degree angle. This angled tip <NUM> allows the user to direct the guidewire into one or another branch vessel more easily. The inner dilator may have a tapered tip, straight as shown in <FIG> or an angled tip as shown in <FIG>. Alternately, the inner dilator may have a constant outer diameter to the distal end, with a rounded leading edge. In an embodiment, the inner dilator has a radiopaque marker <NUM> at or near the distal tip to aid in visualization of the dilator under fluoroscopy. In an embodiment, the inner dilator is reinforced to make it more torquable to aid in directing the angled tip in a particular direction. For example the dilator may have a coil or braid reinforcement layer. Once the interventional wire is positioned, the two-part dilator is removed and the wire may then be used to insert interventional devices through the arterial sheath into the artery and advanced to the treatment site.

An alternate embodiment, shown in <FIG>, allows two separate wire sizes to be used with the dilator. This embodiment includes a dilator <NUM> with two guide wire internal lumens that extend along the length of the device. <FIG> shows the distal end of this embodiment. As seen more clearly in a cross sectional view <FIG>, one lumen <NUM> is configured for an <NUM> or <NUM> (. <NUM>") guidewire, and the other lumen <NUM> is for an <NUM> to <NUM> (. <NUM>") guide wire. In this embodiment, the larger lumen <NUM> is centered around the centerline of the taper <NUM>, whereas the smaller lumen <NUM> is offset from the centerline of the taper. In this configuration, the access sheath is introduced into the artery over the larger guidewire, which is positioned in the larger lumen <NUM>. Once positioned, an interventional wire can be placed through the second lumen <NUM>. The larger guidewire and dilator are then removed from the access sheath and the interventional wire may then be used to insert interventional devices through the arterial sheath into the artery and advanced to the treatment site as above.

Arterial access sheaths are typically introduced into the artery over a sheath guidewire of <NUM> or <NUM> (. <NUM>") diameter. The inner diameter and taper length of the distal tip of the dilator are sized to fit with such a guidewire. Some sheaths, for example for radial artery access, are sized to accommodate a sheath guidewire of <NUM> (<NUM>") diameter, with a corresponding dilator having a distal tip inner diameter and taper length. The sheath guidewire may have an atraumatic straight, angled, or J-tip. The guidewire smoothly transitions to a stiffer segment on the proximal end. This configuration allows atraumatic entry and advancement of the wire into the artery while allowing support for the sheath when the sheath is introduced into the artery over the wire. Typically the transition from the atraumatic tip is about <NUM> to <NUM> to the stiffer section. The sheath is usually inserted <NUM> to <NUM> into the artery, so that the stiffer segment of the wire is at the arterial entry site when the sheath is being inserted.

However, in the case of a transcarotid access entry point, the amount of wire that can be inserted is much less than <NUM> before potentially causing harm to the distal vessels. In a case of a transcarotid access for a carotid stent or PTA procedure, it is very important that the wire insertion length is limited, to avoid risk of distal emboli being generated by the sheath guide wire at the site of carotid artery disease. Thus it is desirable to provide a guide wire that is able to provide support for a potentially steep sheath entry angle while being limited in length of insertion. In an embodiment, a transcarotid sheath guidewire has an atraumatic tip section but has a very distal and short transition to a stiffer section. For example, the soft tip section is <NUM> to <NUM>, followed by a transition section with length from <NUM> to <NUM>, followed by a stiffer proximal segment, with the stiffer proximal section comprising the remainder of the wire. In some implementations, the soft tip section (i.e. the distalmost flexible section including the distal tip of the guidewire) is between <NUM> and <NUM> and the transition section positioned between the flexible distalmost section and the more rigid core section extending proximally from the transition section is between <NUM> and <NUM>.

The sheath guidewire may have guide wire markings <NUM> to help the user determine where the tip of the wire is with respect to the dilator. For example, there may be a marking on the proximal end of the wire corresponding to when the tip of the wire is about to exit the micro access cannula tip. This marking would provide rapid wire position feedback to help the user limit the amount of wire insertion. In another embodiment, the wire may include an additional mark to let the user know the wire has exited the cannula by a set distance, for example <NUM>.

With reference to <FIG>, a micro access kit <NUM> for initial transcarotid access includes an access needle <NUM>, an access guidewire <NUM>, and a micro access cannula <NUM>. The micro access cannula <NUM> includes a body <NUM> and an inner dilator <NUM> slidably positioned within a lumen of the body <NUM>. Typically for arterial access, the initial needle puncture may be with a <NUM> or <NUM> access needle, or an <NUM> needle if the Modified Seldinger technique is used. For transcarotid access, it may be desirable to access with an even smaller needle puncture. Percutaneous access of the carotid artery is typically more challenging than of the femoral artery. The carotid artery is a thicker-walled artery, it is surrounded by a tissue sleeve known as the carotid sheath, and it is not anchored down as much by surrounding musculature, therefore the initial needle stick is more difficult and must be done with more force, onto an artery that is less stable, thus increasing the risk of misplaced puncture, arterial dissection, or back wall puncture. A smaller initial needle puncture, for example a <NUM> or <NUM> needle, increases the ease of needle entry and reduce these risks. The sheath guidewire should be accordingly sized to fit into the smaller needle, for example a <NUM> or <NUM> (<NUM>" or <NUM>") wire. The access needle <NUM> may include a textured surface on the distal end to render it visible on ultrasound, to aid in ultrasound-guided insertion of the needle into the artery. The needle length may be in a range from <NUM> to <NUM> in length.

As best shown in <FIG> and <FIG>, the access needle <NUM> may also include a visible depth indicator <NUM> located near the distal end of the needle shaft. The visible depth indicator <NUM> can be visible to the user without the help of ultrasound or radiography, or other imagining techniques, providing the user with a reference during needle insertion and manipulation of the guidewire during direct insertions into the vessel. The access needle <NUM>, which can be a <NUM>, <NUM>, <NUM>, or <NUM> needle, can have an elongate shaft defining an inner lumen and coupled to a proximal hub <NUM>. The shaft length from the distal end of needle hub <NUM> to the distal tip of its shaft can be between <NUM> to about <NUM>. In some implementations, the shaft length is approximately <NUM> or <NUM>. The visible depth indicator <NUM> can be positioned on the elongate shaft of the needle <NUM> a distance D away from the distal tip of the needle <NUM>, for example about <NUM> to about <NUM>, or preferably <NUM> to <NUM>. In some implementations, the depth indicator <NUM> can have a width W of approximately <NUM> to about <NUM> such that the indicator <NUM> is readily visible to the naked eye during use, such as direct access into the common carotid artery (CCA). Presence of the depth indicator <NUM> reduces the risk that the operator will advance the access needle <NUM> into or through the opposite wall of the vessel. Advancement of the needle <NUM> into the vessel can be metered visually by assessing advancement of the depth indicator <NUM> into the vessel, which is a known distance away from the distal tip. The depth indicator <NUM> can be created using chemical etch, laser-etching, pad printing or other marking methods.

Access guidewires typically used in micropuncture kits can have relatively long distal floppy sections, for example between <NUM>-<NUM> long. However in some applications, such as transcarotid artery revascularization (TCAR), the operator may want to advance the guidewire into the vessel only <NUM>-<NUM> to avoid advancing the tip of the guidewire into a diseased section of the artery. For guidewires with long distal floppy sections, inserting only the first <NUM>-<NUM> of the guidewire means the supportive section of the guidewire remains outside the vessel and only the non-supportive portion of the guidewire is available for advancing the cannula and dilator. Advancing the microaccess cannula and dilator over the non-supportive section of the guidewire carries a higher risk of causing damage to the inner surface of the vessel. Therefore, the access guidewires described herein have a shorter, distal floppy section that allows for a shorter length to be inserted within the vessel while still ensuring the more rigid proximal support section is available within the vessel for advancement of the cannula and dilator over it.

The guidewire <NUM> described herein can have a shorter distalmost flexible section terminating in a distal tip, for example, a flexible section that is just <NUM> to <NUM> long. A transition section proximal to the distalmost flexible section transitions proximally in stiffness towards the stiffer core section extending proximally from the transition section. Such micro access guidewires are typically <NUM> (<NUM>") in diameter, with a distalmost flexible section of about <NUM>-<NUM>, a transition section of <NUM>-<NUM> leading to the stiffer core section extending the remainder of the length of the guidewire. In an embodiment, a transcarotid access guidewire is from <NUM> to <NUM> (<NUM>" to <NUM>") in diameter, and has a distalmost flexible section of <NUM>, a transition section of <NUM>-<NUM> to bring the stiff supportive core section much closer to the distal tip. This will allow the user to have good support for micro access cannula insertion even in steep access angles and limitations on wire insertion length.

As with the sheath guidewire, the micro access guidewire <NUM> may have at least one guidewire marking or depth indicator <NUM> visible to the naked eye that is positioned a known distance from the distal tip of the guidewire <NUM> to help the user determine where the tip of the guidewire <NUM> is with respect to the vessel as well as other components of the microaccess system <NUM>, e.g. the access needle <NUM>, the micro cannula <NUM>, and/or the inner dilator <NUM> (see <FIG> and <FIG>). The depth indicator <NUM> can provide rapid, wire position feedback without any special visualization techniques such as ultrasound or radiography to help the user limit the amount of wire insertion. For example, a depth indicator <NUM> can be located at a first location of the guidewire <NUM> a distance away from the distal tip of the guidewire <NUM> that when aligned with another portion of the system <NUM>, such as the proximal end of the cannula <NUM>, corresponds to when the tip of the wire <NUM> is about to exit the micro cannula <NUM>. In another embodiment, the guidewire <NUM> may include an additional marking <NUM> to let the user know the guidewire <NUM> is about to or has exited the dilator by a set distance, for example <NUM>. In another embodiment, the guidewire <NUM> may include a further marking <NUM> positioned more distally to let the user know when the guidewire <NUM> is inserted through the access needle <NUM> the guidewire <NUM> is about to exit the access needle <NUM> or has exited by a set distance. Thus, the guidewire <NUM> can include a plurality of markings <NUM> that together provide visual guidance related to the depth of insertion and the relative extension of the guidewire <NUM> in relation to other system components.

<FIG> illustrate an implementation of using at least one visible depth indicator on the access guidewire <NUM> that when a portion of the depth indicator is positioned relative to another portion of the system <NUM> can provide the user with rapid, wire position feedback and metering of the advancement of the guidewire <NUM> relative to the vessel and other components of the system <NUM> without needing any special visualization aside from the user's own eyes. This visual reference provides information regarding the distance the guidewire <NUM> extends beyond the access needle <NUM>, for example, and into the vessel. The guidewire <NUM> can include at least one visible depth indicator <NUM> a known distance D from a distal-most end or distal tip of the guidewire <NUM>. The visible depth indicator <NUM> can have a known width W extending between a proximal edge and a distal edge of the indicator <NUM>. For example, one depth indicator <NUM> can be <NUM> wide and the distal edge of the depth indicator <NUM> positioned <NUM> from the distal tip of the guidewire <NUM> such that the proximal edge of the depth indicator <NUM> is positioned <NUM> from the distal tip of the guidewire <NUM>. The distance away from the distal tip of the guidewire <NUM> is measured from the distal tip of the guidewire <NUM> to a distal edge of the at least one visible depth indicator <NUM>. When the access guidewire is inserted through the inner lumen of the elongate shaft of the access needle <NUM> aligning the distal edge of the depth indicator <NUM> with a back end of the proximal hub <NUM> of the access needle <NUM> extends the distal tip of the guidewire <NUM> beyond the distal tip of the elongate shaft a certain extension length. Further advancing the access guidewire <NUM> through the inner lumen of the elongate shaft of the access needle <NUM> until the proximal edge is aligned with the back end of the proximal hub <NUM> of the needle <NUM> extends the distal tip of the guidewire <NUM> beyond the distal tip of the elongate shaft of the access needle <NUM> the extension length plus the width of the depth indicator <NUM>. For example, the needle <NUM> through which the guidewire <NUM> is advanced can measure <NUM> from the back end of the proximal hub <NUM> to the distal tip of the needle. Advancing the guidewire <NUM> through the access needle <NUM> until the distal edge of the depth indicator aligns with the back end of the needle hub <NUM> provides an extension length <NUM> of the guidewire <NUM>, a portion of the guidewire <NUM> extending distal to the distal tip of the needle <NUM>, that is <NUM> long (see <FIG>). Advancing the guidewire <NUM> through the needle <NUM> until the proximal edge of the depth indicator is aligned with the back end of the needle hub <NUM> provides an extension length <NUM> of the guidewire <NUM> distal to the distal tip of the needle <NUM> that is an additional <NUM> or a total of <NUM> long (see <FIG>). It should be appreciated that the guidewire <NUM> may have multiple discrete markings <NUM> to indicate various extension lengths <NUM> and thus depths in the vessel (e.g. <NUM>, <NUM>, <NUM>, etc.) The one or more markings <NUM> can be created by chemical etch, laser marking, pad printing, or other methods.

Typically, the micro access cannula <NUM> includes a cannula body <NUM> configured to receive an inner dilator <NUM> through its lumen, the dilator <NUM> having a tapered tip. The inner dilator <NUM> provides a smooth transition between the cannula <NUM> and the access guide wire <NUM>. The cannula <NUM> is sized to receive the <NUM> (<NUM>") wire, with inner diameter in the range about <NUM> to <NUM> (<NUM>" to about <NUM>"). In an embodiment, a micro access cannula <NUM> is configured for transcarotid access. For example, the dilator <NUM> of the cannula <NUM> may be sized for a smaller <NUM> (<NUM>") access guide wire <NUM>. Additionally, the cannula <NUM> may have one or more visible depth indicators <NUM> to aid the user in assessing the amount of insertion of the cannula <NUM> without any special imaging aside from the naked eye, as will be described in more detail below. A radiopaque material (e.g. barium, bismuth, tungsten) can be added to the entire shaft polymer of the micro access cannula <NUM> and/or dilator <NUM> to provide visibility during fluoroscopy. Alternatively or additionally the micro access cannula <NUM> and/or the dilator <NUM> can have one or more radiopaque markers <NUM>, for example, at the distal tip of the cannula <NUM> or dilator <NUM>, to help the user visualize the tip location under fluoroscopy. This is useful for example in cases where the user may want to position the cannula in the ICA or ECA, for example.

As shown in <FIG>, the microaccess cannula <NUM> can include a plurality of depth indicators <NUM> having a known width W and positioned a known distance D from the distal-most tip of the cannula <NUM>. Each of the plurality of visible depth indicators <NUM> can identify a distance from the distal tip of the cannula <NUM>. The indicators <NUM> can provide rapid metering of the advancement of the cannula <NUM> relative to the insertion point into the vessel as well as other components of the system <NUM> without any special visualization such as ultrasound or radiography. Additionally or alternatively, each of the plurality of visible depth indicators <NUM> can be formed by a number of marks <NUM> such as circumferential rings. Although the marks <NUM> are described herein as being circumferential rings it should be appreciated that the marks <NUM> need not completely encircle the cannula and can take on other shapes such as dots, dashes, or other visible marks.

Each depth indicator <NUM> has at least one mark <NUM>. The number of marks <NUM> forming each of the plurality of depth indicators <NUM> can identify the number of increments that the depth indicator <NUM> is positioned from the distal tip of the cannula <NUM>. This allows for the total distance to be readily and easily surmised simply by looking at the number of marks <NUM> making up each depth indicator <NUM>. In other words, each depth indicator <NUM> can indicate the distance it is from the distal tip of the cannula <NUM> based on the number of marks <NUM> (whether dots, dashes, bands or circumferential rings) forming the particular depth indicator <NUM>. For example, as best shown in <FIG>, a first depth indicator 165a can be formed by a single circumferential ring <NUM> positioned such that a center of the ring <NUM> is a first distance from the distal tip (e.g. <NUM>). A second depth indicator 165b can be formed by two circumferential rings <NUM> positioned such that a center between the pair of rings <NUM> is a second distance from the distal tip (e.g. <NUM>). A third depth indicator 165c can be formed by three circumferential rings <NUM> positioned such that a center of the three rings <NUM> is a third distance from the distal tip (e.g. <NUM>). A fourth depth indicator 165d can be formed by four of the circumferential rings <NUM> positioned such that a center of the four is a fourth distance from the distal tip (e.g. <NUM>). The depth indicators <NUM> can continue in this pattern thereby metering the distance from the distal tip by standard increments in a way that is readily visible and instantaneously understandable to the user.

It should be appreciated that the measured distance need not be from the distal tip to the center of the rings as described above, but instead can be from the distal tip to a distal edge of the mark(s) <NUM> or from the distal tip to a proximal edge of the mark(s) <NUM>. Additionally, one of the depth indicators 165e can be a solid marker of a known width, the middle of which (or distal edge or proximal edge) identifies a known distance from the distal tip of the cannula <NUM> that is generally considered an upper depth limit. In some implementations, the micro access cannula <NUM> is only inserted between <NUM>-<NUM> and an upper depth limit can be generally around <NUM>. These distances can vary and more or fewer depth indicators <NUM> are considered herein. For example, if additional external depth indicators <NUM> are desired the marker increments can be identified by patterns of mark such as <NUM> mark, <NUM> marks, <NUM> marks, <NUM> marks, solid band, as described above and then starting over with <NUM> mark, <NUM> marks, <NUM> marks, <NUM> marks, solid band, and so on. The solid band breaking up the mark pattern provides a quick and easily identifiable indication that the fifth marker increment in the series has been reached without requiring a user to count too many rings. For example, more than <NUM> marks per depth indicator <NUM> can be tedious to differentiate and lead to reading errors by the user. Additionally, an increment size of <NUM> is generally easy to calculate quickly. It should be appreciated, however, that other increment sizes are considered such as <NUM>, <NUM>, or even <NUM> for longer cannulas. One or more of the depth indicators <NUM> can be distinguishable based on its color as well as by the number and/or pattern of marks. For example, a first mark can be a first color, a second mark can be a second color, a third mark can be third color and so on. The marks can be easily distinguishable colors indicating depth of insertion (e.g. white, yellow, orange, red, green, blue, black, etc.) The marks can be within a similar color family, but have an increasing intensity or tone to distinguish the depth of insertion (e.g. a first mark being pale pink towards a last mark being deep red).

The depth indicators <NUM> may be created by pad printing, laser marking, additions of colorant to the cannula material, or other methods. Other components of the micro access kit <NUM> can include similar metering markings as described above. For example, the depth indicators <NUM> of the guidewire <NUM> may also be metered to indicate distance from the distal tip depending on the number of marks (or color, size, shape) per indicator <NUM>. As described above, the sheath body <NUM> and/or the sheath stopper <NUM> can incorporate one or more markings that provide an indication of the depth of insertion of the sheath <NUM>.

Any or all of the devices described above may be provided in kit form to the user such that one or more of the components of the systems are included in a common package or collection of packages.

In an embodiment, a micro access kit comprises an access needle, a micro access guide wire, and a micro access cannula and dilator wherein the guidewire is <NUM> (<NUM>") and the micro access cannula and dilator are sized to be compatible with the <NUM> (<NUM>") guide wire.

In an embodiment, an access kit comprises the access sheath, sheath dilator, sheath guide wire, access needle, micro access guide wire and micro access cannula and dilator, all configured for transcarotid access.

In an alternate embodiment, the access guidewire is also used as the sheath guide wire. In this embodiment, the access kit comprises an access needle, access guide wire, access sheath and dilator. The sheath and dilator use the access guide wire to be inserted into the vessel, thereby avoiding the steps required to exchange up to a larger sheath guidewire. In this embodiment, the dilator taper length and inner lumen is sized to be compatible with the smaller access guide wire. In one embodiment, the access guide wire is <NUM> (<NUM>"). In an alternate embodiment the access guide wire is <NUM> (<NUM>"). In an alternate embodiment, the access guide wire is <NUM> (<NUM>").

There are now described exemplary methods (not claimed according to the present invention) of use for a transcarotid access system. In an exemplary transcarotid procedure to treat a carotid artery stenosis, the user starts by performing a cut down to the common carotid artery. The user then inserts an access needle <NUM> into the common carotid artery at the desired access site. An access guide wire <NUM> with a taper configured for transcarotid access is inserted through the needle into the common carotid artery and advanced into the CCA. The access needle <NUM> is removed and a micro access cannula <NUM> is inserted over the wire <NUM> into the CCA. The micro access cannula is inserted a desired depth using the marks <NUM> on the cannula as a guide, to prevent over insertion.

The user removes the cannula inner dilator <NUM> and guide wire <NUM>, leaving the cannula <NUM> in place. If desired, the user performs an angiogram through the cannula <NUM>. The user then places sheath guide wire <NUM> through the cannula, using guide wire markings <NUM> to aid in inserting the wire to a desired insertion length. The cannula <NUM> is removed from the guidewire and the access sheath <NUM> and sheath dilator <NUM> are inserted as an assembly over the sheath guidewire <NUM> into the CCA. The sheath stopper flange <NUM> of the sheath stopper <NUM> limits the insertion length of the arterial sheath. Once positioned, the dilator <NUM> and guidewire <NUM> are removed. The sheath is then sutured to the patient using the securing eyelets <NUM>, ribs <NUM>, and/or suture grooves 1120a. An interventional procedure is then performed by introduction of interventional devices through hemostasis valve <NUM> on the proximal end of the arterial sheath and to the desire treatment site. Contrast injections may be made as desired during the procedure via the flush arm <NUM> on the arterial sheath <NUM>.

Alternately, the user inserts an access needle <NUM> directly into the common carotid artery at the desired access site visually monitoring a depth indicator <NUM> on the needle <NUM>. Vessel wall thickness is typically <NUM>-<NUM> and the vessel diameter of the common carotid artery is typically <NUM>-<NUM>. Thus, maintaining the depth indicator <NUM> positioned <NUM> from the distal tip in view outside the vessel ensures the distance the needle is inserted will penetrate the wall thickness fully without contacting the back side of the vessel wall.

Alternately or additionally, an access guidewire <NUM> configured for transcarotid access is inserted through the hub <NUM> of the needle <NUM> until a portion of the depth marker <NUM> aligns with another portion of the needle <NUM> identifying a desired amount of extension length <NUM> of the guidewire <NUM> is positioned within the common carotid artery. For example, the proximal edge of the depth marker <NUM> on the guidewire <NUM> can be aligned with the back end of the needle hub <NUM> indicating <NUM> of wire has been advanced beyond the distal tip of the needle <NUM> into the common carotid artery. Alternatively, the distal edge of the depth marker <NUM> is aligned with the back end of the needle hub <NUM> indicating <NUM> of wire beyond the distal tip of the needle into the common carotid artery.

Leaving the access guidewire <NUM> in place, the access needle <NUM> is carefully withdrawn from the vessel. The micropuncture cannula <NUM> having the inner dilator <NUM> extending through its lumen is advanced over the access guidewire <NUM> into the vessel through the puncture. The depth markings <NUM> of the micropuncture cannula <NUM> are monitored visually by the user to confirm desired depth of micropuncture cannula insertion and to prevent over-insertion. The micropuncture cannula <NUM> is left in place once desired depth is reached, and the dilator <NUM> and access guidewire <NUM> are carefully withdrawn.

Alternately, the sheath guidewire <NUM> is placed into the CCA via a single needle puncture with a larger access needle, for example an <NUM> needle. In this embodiment, the access cannula and access guide wire are not needed. This example reduces the number of steps required to access the artery, and in some circumstances may be desirable to the user.

Alternately, the sheath dilator is a two-part sheath dilator assembly <NUM> as shown in <FIG>, with an inner dilator <NUM> and an outer dilator <NUM>. The outer dilator <NUM> is configured to receive an <NUM> (. <NUM>") sheath guide wire <NUM> and to provide a smooth transition from the <NUM> (. <NUM>") wire to the access sheath <NUM>. The inner dilator <NUM> is configured to receive a smaller guide wire in the range <NUM> to <NUM> (. <NUM>") and to provide a smooth transition from the smaller guide wire to the outer dilator <NUM>. Once the sheath guidewire is positioned in the CCA, the access sheath and outer sheath dilator <NUM> are inserted over an <NUM> (. <NUM>") sheath guidewire <NUM> into the CCA. The guidewire is then removed and an inner sheath dilator <NUM> is inserted into the outer sheath dilator. In an example, the inner sheath dilator has an angled tip <NUM> as seen in <FIG>. An interventional <NUM> (. <NUM>") guide wire is inserted through the inner sheath dilator and is directed to the target treatment site using the angled tip to aid in guide wire positioning. Alternately, the inner sheath dilator has a straight tip and is used to aid in positioning the guide wire safely into the CCA. Once the <NUM> (. <NUM>") wire is positioned at or across the target treatment site, the sheath dilator <NUM> and sheath <NUM> (. <NUM>") guide wire <NUM> are then removed, and the intervention proceeds.

In an alternate example, the sheath dilator is a two lumen sheath dilator <NUM>. In this embodiment, the sheath and dilator are inserted over the sheath guide wire <NUM>, with the sheath guidewire positioned in the larger lumen <NUM> of dilator <NUM>. Once the sheath and dilator is in place, an interventional <NUM> (. <NUM>") guide wire is positioned through the smaller lumen <NUM>. The dilator provides distal support and maintains the position of the sheath tip in the axial direction of the vessel lumen, thus allowing a potentially safer and easier advancement of the <NUM> (. <NUM>") wire than if the dilator were removed and the sheath tip was directed at least partially towards to posterior wall of the artery. Once the <NUM> (. <NUM>") wire is positioned at or across the target treatment site, the sheath dilator <NUM> and sheath guide wire <NUM> (. <NUM>") are then removed, and the intervention proceeds.

In yet another example, it may be desirable to occlude the CCA during the intervention to minimize antegrade flow of emboli. In this embodiment, the occlusion step may be performed via vascular surgical means such as with a vessel loop, tourniquet, or vascular clamp. In an alternate embodiment, the access sheath <NUM> has an occlusion element such as an occlusion balloon <NUM> on the distal tip. In this embodiment, the balloon is inflated when CCA occlusion is desired. In a further variant, while the CCA is occluded either surgically or via balloon occlusion, it may be desirable to connect the arterial sheath to a flow shunt, for example to create a reverse flow system around the area of the treatment site to minimize distal emboli. In this embodiment, the arterial sheath <NUM> has a Y connection to a flow line <NUM>. The flow line <NUM> may be connected to a return site with a pressure lower than arterial pressure to create a pressure gradient that results in reverse flow through the shunt, for example an external reservoir or a central venous return site like the femoral vein or the internal jugular vein. Alternately, the flow line may be connected to an aspiration source such as an aspiration pump or syringe.

In another example, a transcarotid access system is used to perform a percutaneous neurointerventional procedure. In this example, the user performs a percutaneous puncture of the common carotid artery CCA with an access needle <NUM> at the desired access site. Ultrasound may be used to accurately identify a suitable access site and guide the needle puncture. An access guide wire <NUM> is inserted through the needle into the common carotid artery and advanced into the CCA. The access needle <NUM> is removed and a micro access cannula <NUM> is inserted over the wire <NUM> into the CCA. The user removes the cannula inner dilator <NUM> and guide wire <NUM>, leaving the cannula <NUM> in place. If desired, the user performs an angiogram through the cannula <NUM>. The user then places sheath guide wire <NUM> through the cannula, using guide wire markings <NUM> to aid in desired insertion length. The cannula <NUM> is removed from the guidewire and the access sheath <NUM> and sheath dilator <NUM> are inserted as an assembly over the sheath guidewire <NUM> into the CCA.

Alternately, the smaller access guide wire <NUM> is used to position the access sheath <NUM> and sheath dilator <NUM> into the CCA. In this example, the sheath dilator tapered tip <NUM> has been configured to transition smoothly from the access guide wire <NUM> to the access sheath <NUM>. In one variant, the access needle is <NUM> and the access guide wire is <NUM> (<NUM>"). In another variant, the access needle is <NUM> and the access guide wire is <NUM> (<NUM>"). Once the sheath is placed, the guide wire and sheath dilator are removed and an interventional procedure is then performed by introduction of interventional devices through hemostasis valve <NUM> on the proximal end of the arterial sheath and to the desire treatment site. Contrast injections may be made as desired during the procedure via the flush arm <NUM> on the arterial sheath <NUM>.

Alternately, it may be desirable once the sheath is placed in the CCA to advance it further into the ICA, for example in the mid to distal cervical ICA, petrous ICA or further distally. In this example, the sheath dilator may be replaced with a softer sheath dilator so that the sheath may be advanced without risk of damaging the distal ICA. In this example, the softer dilator has a distal radiopaque marker so that the user may easily visualize the leading edge of the sheath and dilator assembly during positioning of the sheath. Once the access sheath is positioned, the dilator and sheath guide wire may be removed and the intervention can proceed. Alternately, once the sheath is placed in the CCA, the <NUM> (. <NUM>") guide wire may be removed and an inner dilator with a smaller guidewire in the range <NUM> to <NUM> (. <NUM>") may be inserted into sheath dilator. The sheath dilator assembly with the inner dilator and smaller guide wire may be then positioned more distally in the ICA with reduced risk of vessel trauma.

In an example, it may be desirable to occlude the CCA or ICA during portions of the procedure to reduce the chance of distal emboli flowing to the brain. In this embodiment, the CCA or ICA is occluded by means of an occlusion balloon <NUM> on the access sheath <NUM>. It may also be desirable to connect the arterial sheath to a flow shunt, for example to create a reverse flow system around the area of the treatment site to minimize distal emboli. In this embodiment, the arterial sheath <NUM> has a Y connection to a flow line <NUM>. The flow line may be connected to a return site with a pressure lower than arterial pressure to create a pressure gradient that results in reverse flow through the shunt. Alternately, the flow line may be connected to an aspiration source such as an aspiration pump or syringe.

Claim 1:
A micropuncture kit for direct access into a lumen of a surgically exposed vessel using direct visual guidance, the kit comprising:
a micropuncture access needle (<NUM>) comprising a proximal hub coupled to an elongate shaft defining an inner lumen and an access needle visible depth indicator (<NUM>) positioned on the elongate shaft;
a microaccess cannula (<NUM>) comprising an elongate body defining an inner lumen and a plurality of microaccess cannula visible depth indicators (<NUM>) formed on the elongate body, wherein each of the plurality of visible depth indicators (<NUM>) identifies a distance from a distal tip of the cannula (<NUM>);
an access guidewire (<NUM>) sized to be received through the inner lumen of the micropuncture access needle (<NUM>), the guidewire (<NUM>) comprising a distal tip and a first visible depth indicator (<NUM>), characterised by the kit further comprising: a second visible depth indicator, and a third visible depth indicator each positioned on the access guidewire (<NUM>) a distance away from the distal tip of the guidewire; and
wherein the first visible depth indicator (<NUM>) aligns with a proximal edge of the microaccess cannula (<NUM>) to provides a visual indication to a user that the distal tip of the access guidewire (<NUM>) is aligned with the distal tip of the microaccess cannula (<NUM>);
wherein the second visible depth indicator aligns with the proximal edge of the microaccess cannula (<NUM>) to provides a visual indication to a user that the distal tip of the access guidewire (<NUM>) is aligned with the distal tip of the micropuncture access needle (<NUM>);
wherein the third visible depth indicator aligns with the proximal edge of the microaccess cannula (<NUM>) to provides a visual indication to a user that the distal tip of the access guidewire (<NUM>) is positioned distally of the distal tip of the micropuncture access needle (<NUM>) by a predetermined distance indicated by the third visible depth indicator.