Patent Description:
The present disclosure relates generally to the field of medical devices. More particularly, some embodiments relate to vascular access technologies, such as vascular access assemblies that facilitate hemodialysis. <CIT> describes an endovascular anastomotic connector that includes an endovascular component and a vascular conduit and a supply conduit that forms a bifurcation joint with the vascular conduit, wherein the vascular conduit s a single tube where both ends are within the vasculature and does not include a first branch configured to couple to an artery and a second branch coupled to the second tubular conduit.

<CIT> retates to a vascular prosthesis system comprising an introducing system for introducing a vascular prosthesis intraluminally into a blood vessel and expanding an outer end thereof in situ. The introducing system comprises a first placing device for placing and temporarily holding an external fixation body outside the blood vessel. The introducing system also comprises a second placing device for placing and expanding in situ the vascular prosthesis in the blood vessel. The first and second placing devices are provided with mutually co-acting registering means which give an indication detectable externally of the blood vessel of a correct registering of the expandable outer end of the vascular prosthesis in the blood vessel relative to the fixation body outside the blood vessel.

The written disclosure herein describes illustrative embodiments that are nonlimiting and non-exhaustive. Reference is made to certain of such illustrative embodiments that are depicted in the figures, in which:.

Many patients that suffer from kidney malfunction undergo hemodialysis to remove waste products from their blood. Hemodialysis generally requires access to an adequate blood supply. In some cases, access to a blood supply may be established via an arteriovenous fistula. In other circumstances, other methods for accessing the blood supply are used.

For example, in some embodiments, access to a blood supply is established via an arteriovenous graft. In other embodiments, access to a blood supply is established via a graft that extends from a peripheral blood supply to an outlet that is positioned in the central venous system.

Certain embodiments disclosed herein may be used to establish an artificial blood flow path, such as along a non-natural or artificial conduit, that improves or provides alternative access to a blood supply. The artificial flow path may be used, for example, to bypass a central venous stenosis. In some embodiments, the artificial blood flow path, when implanted into a patient, is fully subcutaneous. Access to a blood supply that is provided by an artificial flow path may be particularly advantageous for access in hemodialysis patients (such as hemodialysis patients that have exhausted peripheral venous access sites for fistulas).

The components of the embodiments as generally described and illustrated in the figures herein can be arranged and designed in a wide variety of different configurations. While various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The phrase "coupled to" is broad enough to refer to any suitable coupling or other form of interaction between two or more entities. Thus, two components may be coupled to each other even though they are not in direct contact with each other. For example, two components may be coupled to each other through an intermediate component. The phrase "attached to" refers to interaction between two or more entities which are in direct contact with each other and/or are separated from each other only by a fastener of any suitable variety (e.g., an adhesive). The phrase "fluid communication" is broad enough to refer to arrangements in which a fluid (e.g., blood) can flow from one element to another element when the elements are in fluid communication with each other. Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints.

The terms "central" and "peripheral," as used herein, are opposite directional terms. For example, a peripheral end of a device or component is the end of the device or component that is furthest from the heart when the device or component is assembled and implanted within the patient. The central end refers to the opposite end, or the end closest to the heart of the patient when the device is in use. Further, this reference frame is applied herein to devices configured or designed to have one end (a central end) positioned closer to the heart when the device is in use, whether or not the device itself is deployed within the body.

<FIG> and <FIG> provide perspective views of a vascular access assembly <NUM> in different states. As shown in <FIG> and <FIG>, the vascular access assembly <NUM> includes a first tubular conduit <NUM>, a second tubular conduit <NUM>, and an expandable stent graft <NUM>.

In some embodiments, the first tubular conduit <NUM> has an initial length of at least <NUM>, at least <NUM>, at least <NUM>, and/or at least <NUM>. For example, the first tubular conduit <NUM> may have an initial length of between <NUM> and <NUM> and/or between <NUM> and <NUM>. In some embodiments, the first tubular conduit <NUM> has an internal diameter of between <NUM> and <NUM>. For example, in some embodiments, the internal diameter of the first tubular conduit <NUM> is between <NUM> and <NUM>.

In some embodiments, the first tubular conduit <NUM> is resistant to kinking and/or crush forces. In some embodiments, the first tubular conduit <NUM> is reinforced with nitinol, such as braided nitinol, which provides resistance to kinking and/or crush forces. More specifically, in some embodiments, the first tubular conduit <NUM> includes silicone-coated nitinol.

In some embodiments, the first tubular conduit <NUM> includes one or more radiopaque bands or markers (not shown). For example, the first tubular conduit <NUM> may include a radiopaque band adjacent the central end of the first tubular conduit <NUM>. The radiopaque band(s) or marker(s) may facilitate fluoroscopic placement of the first tubular conduit <NUM> within a patient.

In some embodiments, the second tubular conduit <NUM> is configured to be accessed for hemodialysis. In other words, during some medical procedures (e.g., hemodialysis), the second tubular conduit <NUM> may be accessed in lieu of the natural vasculature of a patient. In some embodiments, the second tubular conduit <NUM> comprises and/or consists of polytetrafluoroethylene (PTFE), such as expanded PTFE (ePTFE), rotational spun PTFE, or electrospun PTFE. In some embodiments, the second tubular conduit <NUM> comprises silicone. In some embodiments, the second tubular conduit <NUM> comprises a fibrous polymer.

In some embodiments, the second tubular conduit <NUM> includes a puncturable and self-sealing wall such that the wall may be punctured by insertion of a needle and then reseal upon withdrawal of the needle. The self-sealing wall may be of any suitable composition. In some embodiments, the self-sealing wall is a multi-layered construct. For example, some embodiments include an outer layer, an inner layer, and at least one tie layer disposed between the outer layer and the inner layer. In some embodiments, one or more of the outer layer and the inner layer comprise PTFE. For example, the outer layer may comprise or consist of expanded PTFE, while the inner layer comprises and/or consists of rotational spun or electrospun PTFE. In some embodiments, the tie layer comprises an elastomer, such as elastomeric silicone. Due, at least in part, to the properties of the silicone, the resulting construct may be self-sealing. In other words, when a needle that has been inserted through the wall is withdrawn from the second tubular conduit <NUM>, the wall may seal itself, thereby preventing leakage of blood from the second tubular conduit <NUM>.

In some embodiments, the second tubular conduit <NUM> has an initial length of at least <NUM>, at least <NUM>, and/or at least <NUM>. In some embodiments, the second tubular conduit <NUM> is between <NUM> and <NUM> and/or between <NUM> and <NUM> in length. In some embodiments, the second tubular conduit <NUM> has an internal diameter of between <NUM> and <NUM>. For example, in some embodiments, the internal diameter of the second tubular conduit <NUM> is between <NUM> and <NUM>.

In some embodiments, both the first tubular conduit <NUM> and the second tubular conduit <NUM> are self-sealing. In other embodiments, only the second tubular conduit <NUM> is self-sealing.

The expandable stent graft <NUM> may be coupled to and disposed adjacent to a peripheral end of the second tubular conduit <NUM>. In some embodiments, the expandable stent graft <NUM> is coupled to the peripheral end of the second tubular conduit <NUM> such that there is a continuous luminal surface for contacting blood. For example, in some embodiments, the vascular access assembly <NUM> includes a tubular liner that is disposed within both the expandable stent graft <NUM> and the second tubular conduit <NUM>. The tubular liner may provide a continuous luminal surface for contact with blood from the patient. In this manner, the luminal surface formed by the expandable stent graft <NUM> and the second tubular conduit <NUM> may be free from seams, joints, or other discontinuities.

The expandable stent graft <NUM> may be unbranched as depicted in <FIG> or branched (see <FIG> and <FIG>). The unbranched expandable stent graft <NUM> may be sized for positioning within and coupling to an arteriovenous graft of a patient. In other words, the unbranched expandable stent graft <NUM> may be positioned within a blocked or failing artervenious graft to divert substantially all of the blood from the arteriovenous graft to a flow path defined, at least in part, by the second tubular conduit <NUM>.

The stent of the expandable stent graft <NUM> may be made from any suitable material, such as steel or nitinol. The expandable stent graft <NUM> may also include a coat. The coat may be made from any suitable material. For example, in some embodiments, the coat is formed from PTFE, such as fibrous (e.g., electrospun or rotational spun) PTFE. Other polymers may also be used to form the coat of the expandable stent graft <NUM>. The expandable stent graft <NUM> may be configured to transition from a compact state as shown in <FIG> to a deployed state as shown in <FIG>. In some embodiments, the expandable stent graft <NUM> is expanded (and thereby deployed) by inflation of a balloon that is positioned within a lumen of the expandable stent graft <NUM>. The expandable stent graft <NUM> is a self-expanding stent graft that transitions from the compact state to the expanded state when a restraint, such as a sheath or other delivery constraint, is removed from around the expandable stent graft <NUM>. The restraint is removed by use of a pull string <NUM> that releases the restraint. The restraint comprises filaments that extend around a circumference of the expandable stent graft <NUM> in a compressed state. These filaments are coupled to the pull string <NUM> such that displacement of the pull string <NUM> decouples the filaments from the expandable stent graft <NUM> allowing the expandable stent graft <NUM> to expand. The expandable stent graft <NUM> is biased to adopt the expanded state when unconstrained. As described below, the expandable stent graft <NUM> may be configured to couple to an arteriovenous graft of a patient such that the arteriovenous graft is in fluid communication with the second tubular conduit <NUM>.

In some embodiments, one or both of the inner surface and the outer surface of the vascular access assembly <NUM> may be associated with a therapeutic agent. In other words, the therapeutic agent may be disposed on or embedded within a surface of the vascular access assembly <NUM>. The therapeutic agent may be released from the surface(s) of the vascular access assembly <NUM> to deliver a therapeutically effective dose of the therapeutic agent to the patient when the vascular access assembly <NUM> is implanted within a patient. In some embodiments, a first therapeutic agent is associated with the inner surface of the vascular access assembly <NUM> and a second therapeutic agent that differs from the first therapeutic agent is associated with the outer surface of the vascular access assembly <NUM>. In such embodiments, both the first therapeutic agent and the second therapeutic agent may be delivered into the bloodstream of the patient in therapeutically effective doses when the vascular access assembly <NUM> is implanted within the patient. In some embodiments, heparin is used as a therapeutic agent. In some embodiments, the therapeutic agent reduces thrombus or tissue proliferation.

In some embodiments, the vascular access assembly <NUM> further includes one or more connectors <NUM> that facilitate coupling of the first tubular conduit <NUM> to the second tubular conduit <NUM>. In some embodiments, such as the embodiment shown in <FIG> and <FIG>, the connector <NUM> is disposed at a central end the second tubular conduit <NUM>.

In the depicted embodiment, the connector <NUM> includes one or more barbs or protrusions <NUM> that are designed to engage with an inner diameter of the first tubular conduit <NUM> to form a fluid-tight connection. While <FIG> and <FIG> show the connector <NUM> at the central end of the second tubular conduit <NUM>, a skilled artisan will recognize that, in other embodiments, the connector <NUM> may instead be disposed at a peripheral end of the first tubular conduit <NUM>. In still other embodiments, the connector <NUM> may include components disposed at both the central end of the second tubular conduit <NUM> and the peripheral end of the first tubular conduit <NUM>. The connector <NUM> may be made from any suitable material, such as steel or titanium.

The vascular access assembly <NUM> may be used in any suitable medical procedure, such as to establish vascular access for hemodialysis. For example, where an arteriovenous graft has become occluded or otherwise failed, an alternative artificial flow path that bypasses the occlusion or failure may be established. For example, an artificial flow path may be established from a portion of the arteriovenous graft that is upstream of the occlusion or failure in the arteriovenous graft to the right atrium of the heart.

As shown in <FIG>, such a medical procedure may initially involve making a first incision <NUM> in or adjacent to the neck of a patient <NUM> to access the internal jugular vein of the patient <NUM>. A guidewire may then be passed into the internal jugular vein to the inferior vena cava, followed by a dilator that is passed over the guidewire to facilitate insertion of an introducer. The dilator may then be removed, and the introducer passed over the guidewire into the internal jugular vein of the patient <NUM>. Once the introducer is placed within the internal jugular vein, a central end <NUM> of the first tubular conduit <NUM> may be inserted through the introducer and advanced within the patient <NUM> such that the central end <NUM> of the first tubular conduit <NUM> passes through the superior vena cava into the right atrium of a heart <NUM> as depicted in <FIG>. Advancement of the first tubular conduit <NUM> into the patient <NUM> may be done under fluoroscopic guidance.

After the central end <NUM> of the first tubular conduit <NUM> has been placed within the right atrium of the heart <NUM>, a second incision <NUM> (see <FIG>) may be made in the shoulder region of the patient <NUM> (e.g., adjacent the deltopectoral groove). A tunneling device may then be used to establish a subcutaneous path between the first incision <NUM> in the neck region of the patient <NUM> and the second incision <NUM> in the shoulder region of the patient <NUM>. The peripheral end <NUM> of the first tubular conduit <NUM> may then be inserted into the first incision <NUM> and advanced along the path established by the tunneling device (i.e., the first tubular conduit <NUM> is tunneled) such that the first tubular conduit <NUM> extends from the right atrium of the heart <NUM> to the second incision <NUM> in the shoulder region of the patient <NUM> as shown in <FIG>.

Once the first tubular conduit <NUM> has been placed such that the first tubular conduit <NUM> extends from the right atrium of the heart <NUM> to the second incision <NUM> in the shoulder region of the patient <NUM>, a third incision <NUM> (see <FIG>) may be made in the arm of the patient <NUM> adjacent the target site of an arteriovenous graft <NUM>. For example, the third incision <NUM> may be made at a position that is upstream of an occlusion or failure in the arteriovenous graft <NUM>. The expandable stent graft <NUM> at the peripheral end of the second tubular conduit <NUM> may then be coupled to the arteriovenous graft <NUM> adjacent the third incision <NUM> in the arm of the patient <NUM> (see <FIG> and <FIG>). For example, in some embodiments, the arteriovenous graft <NUM> may be pierced adjacent the third incision <NUM> by a needle. A guidewire may then be inserted through the needle and into the arteriovenous graft <NUM> of the patient <NUM>. In some embodiments, a distal end of a stent graft deployment device (not shown) may then be passed over the guidewire and inserted into the arteriovenous graft <NUM> of the patient <NUM>. The practitioner may then manipulate the stent graft deployment device and expandable stent graft <NUM> to deploy the expandable stent graft <NUM> in the arteriovenous graft <NUM> of the patient <NUM>. For example, a sheath of the stent graft deployment device may be retracted, thereby allowing a self-expanding stent to deploy within the arteriovenous graft <NUM> of the patient <NUM>. In some such embodiments, the second tubular conduit <NUM> may be disposed within a deployment device such that the expandable stent graft <NUM> is disposed distal (along the deployment device) from the remaining portion of the second tubular conduit <NUM>, allowing the expandable stent graft <NUM> to be advanced by the deployment device into a bodily structure before the remaining portion of the second tubular conduit <NUM>. In other embodiments, a pull string <NUM> (see <FIG> and <FIG>) is used to deploy the expandable stent graft <NUM> within the arteriovenous graft <NUM> of the patient <NUM>. In still other embodiments, the expandable stent graft <NUM> is deployed via a balloon catheter.

In other words, the expandable stent graft <NUM> may be inserted into the arteriovenous graft <NUM> when in a compact state. Once the expandable stent graft <NUM> is appropriately positioned within the arteriovenous graft <NUM>, the expandable stent graft <NUM> may be deployed, thereby forming a fluid-tight seal with the arteriovenous graft <NUM> as shown in <FIG> and <FIG>. The fluid-tight seal formed by deployment of the expandable stent graft <NUM> may divert essentially all of the blood from the arteriovenous graft <NUM> into the second tubular conduit <NUM> of the vascular access assembly <NUM>.

A tunneling device may then be used to establish a subcutaneous path between the third incision <NUM> in the arm of the patient <NUM> to the second incision <NUM> in the shoulder region of the patient <NUM> (see <FIG>). The second tubular conduit <NUM> may then be inserted into and advanced through the tunneling device such that the second tubular conduit <NUM> extends from the third incision <NUM> to the second incision <NUM>. The tunneling device may then be removed such that the second tubular conduit <NUM> is disposed within the patient <NUM> as shown in <FIG>. In this manner, the tunneling device may facilitate placement and delivery of the second tubular conduit <NUM> within the patient <NUM>.

With the central end <NUM> of the first tubular conduit <NUM> disposed within the right atrium of the heart <NUM> of the patient <NUM>, the peripheral end of the first tubular conduit <NUM> may then, if needed, be cut to the appropriate length. In other words, the first tubular conduit <NUM> may initially (e.g., when manufactured and inserted as described above) have a length that is longer than is needed to establish a flow path from the right atrium of the heart <NUM> of the patient <NUM> to the second incision <NUM> in the shoulder region of the patient <NUM>. The first tubular conduit <NUM> may then be cut to proper length to facilitate coupling of the second tubular conduit <NUM> to the first tubular conduit <NUM> at the second incision <NUM> in the shoulder region of the patient <NUM>.

Similarly, in some embodiments, the second tubular conduit <NUM> has an initial length that is longer than is needed to establish a flow path from the second incision <NUM> in the shoulder region of the patient <NUM> to the third incision <NUM> in the arm of the patient <NUM>. In such embodiments, the central end of the second tubular conduit <NUM> may be cut to the appropriate length once the second tubular conduit <NUM> has been inserted into the patient <NUM>. In some embodiments, the connector <NUM> (see <FIG>) may then be attached to the newly formed central end of the second tubular conduit <NUM>. In other embodiments, no cutting of the second tubular conduit <NUM> is needed.

Once the first tubular conduit <NUM> and the second tubular conduit <NUM> are the proper length, the second tubular conduit <NUM> may be coupled to the first tubular conduit <NUM>. For example, the connector <NUM> at the central end of the second tubular conduit <NUM> may be inserted to the peripheral end <NUM> of the first tubular conduit <NUM> such that the barbs or protrusions <NUM> of the connector <NUM> engage with an inner diameter of the first tubular conduit <NUM> (see <FIG>). Such engagement may establish a fluid-tight connection between the first tubular conduit <NUM> and the second tubular conduit <NUM>. Establishment of a fluid-tight connection can be confirmed by attaching the peripheral end of the second tubular conduit <NUM> to a syringe and advancing fluid (e.g., heparinized saline) through the system.

Once a flow path from the arteriovenous graft <NUM> to the heart <NUM> has been established as shown in <FIG>, the first incision <NUM>, the second incision <NUM>, and the third incision <NUM> may be closed via any suitable technique. In this manner, the vascular access assembly <NUM> may, when implanted and assembled, be a fully subcutaneous surgical implant. The implanted and assembled vascular access assembly <NUM> may also, as described above, be implanted without establishing a venous anastomosis.

The implanted vascular access assembly <NUM> may be used to facilitate vascular access. For example, in the case of hemodialysis, a practitioner may insert a first needle through the skin of the patient <NUM> and into the vascular access assembly <NUM>. More particularly, the first needle may be inserted into the second tubular conduit <NUM>. Fluid may be withdrawn from the vascular access assembly <NUM> and drawn into a dialysis machine that purifies the blood. The purified blood may then be returned to the patient <NUM> via a second needle that extends through the skin of the patient <NUM> and into more central location of the second tubular conduit <NUM>.

The steps of the procedure described above are only exemplary in nature. In other words, the vascular access assembly <NUM> may be implanted into the patient <NUM> via a procedure that deviates somewhat from the procedure described above. One of ordinary skill in the art, having the benefit of this disclosure, will also appreciate that some of the steps described above need not be performed in the precise order that is specified above.

<FIG> and <FIG> depict an embodiment of a vascular access assembly <NUM> of the present invention, that resembles the vascular access assembly <NUM> described above in certain respects. Accordingly, like features are designated with like reference numerals, with the leading digits incremented to "<NUM>. " For example, the embodiment depicted in <FIG> and <FIG> includes a first tubular conduit <NUM> that may, in some respects, resemble the first tubular conduit <NUM> of <FIG>. Relevant disclosure set forth above regarding similarly identified features thus may not be repeated hereafter. Moreover, specific features of the vascular access assembly <NUM> and related components shown in <FIG> may not be shown or identified by a reference numeral in the drawings or specifically discussed in the written description that follows. However, such features may clearly be the same, or substantially the same, as features depicted in other embodiments and/or described with respect to such embodiments. Accordingly, the relevant descriptions of such features apply equally to the features of the vascular access assembly <NUM> and related components depicted in <FIG> and <FIG>. Any suitable combination of the features, and variations of the same, described with respect to the vascular access assembly <NUM> and related components illustrated in <FIG> can be employed with the vascular access assembly <NUM> and related components of <FIG> and <FIG>, and vice versa. This pattern of disclosure applies equally to further embodiments depicted in subsequent figures and described hereafter, wherein the leading digits may be further incremented.

<FIG> depicts the implanted vascular access assembly <NUM> with an expandable stent graft <NUM> that, in contrast to the embodiment depicted in <FIG>, is branched. A close-up view of a portion of the vascular access assembly <NUM> is depicted in <FIG>. The branched expandable stent graft <NUM> of the vascular access assembly <NUM> may be used to couple to an artery <NUM> of the patient <NUM>. In other words, the vascular access assembly <NUM> may be configured for coupling to an artery <NUM> of the patient <NUM> instead of coupling to an arteriovenous graft as described above in connection with <FIG>.

The vascular access assembly <NUM> may be implanted within the patient <NUM> in a manner analogous to the procedure described above in connection with the vascular access assembly <NUM>. However, instead of inserting the expandable stent graft <NUM> at the peripheral end of a second tubular conduit <NUM> into an arteriovenous graft, the expandable stent graft <NUM> may be inserted into and deployed in an artery <NUM> (e.g., a brachial artery) such that a first branch of the expandable stent graft <NUM> permits fluid flow through the artery <NUM> and a second branch is configured to direct blood from the artery <NUM> to the right atrium of the heart <NUM> of the patient <NUM>. In this manner, an artificial fully subcutaneous flow path may be established from an artery <NUM> to the heart <NUM> of the patient <NUM>.

In the depicted embodiment, the branched expandable stent graft <NUM> is T-shaped. However, in other embodiments, the branched stent graft may be some other branched shape (e.g., Y-shaped). The portions of the expandable stent graft <NUM> configured for displacement within the artery may be sized such that an outside diameter of the expandable stent graft <NUM> contacts the inside diameter of the artery wall, in some instances sealing against the wall to prevent blood flow around the outside diameter of the expandable stent graft <NUM>.

<FIG> are alternative views of a portion of a vascular access assembly <NUM> according to another embodiment. More particularly, <FIG> depict a second tubular conduit <NUM> and an expandable stent graft <NUM> that is coupled to the peripheral end of the second tubular conduit <NUM>. In the depicted embodiment, the vascular access assembly <NUM> includes a collar <NUM> that is disposed around a periphery of the expandable stent graft <NUM>.

In some embodiments, the collar <NUM> is configured to transition between a compact state (<FIG>) in which the collar <NUM> adopts a low-profile configuration to a deployed state (<FIG> and <FIG>) in which the collar <NUM> extends outward from the exterior surface of the expandable stent graft <NUM>. When the expandable stent graft <NUM> is initially inserted into the arteriovenous graft <NUM> or an artery of the patient <NUM>, the collar <NUM> may be in a compact state as shown in <FIG>. Once the expandable stent graft <NUM> has been inserted into the arteriovenous graft <NUM> or the artery of the patient <NUM>, the collar <NUM> may transition to the deployed state as shown in <FIG>. In some embodiments, this transition occurs as the expandable stent graft <NUM> is deployed. In some instances, the collar <NUM> may be deployed before the entire expandable stent graft <NUM> to facilitate positioning of the expandable stent graft <NUM>. For example, an expanded collar <NUM> may be brought into contact with a wall of the arteriovenous graft <NUM> or an artery of the patent <NUM>, before the entire expandable stent graft <NUM> is expanded and is thus more easily displaceable. The collar <NUM> may be any suitable shape. For example, in the depicted embodiment, the collar <NUM> is a relatively thin, ringshaped sheet of material.

In some embodiments, the collar <NUM>, when unconstrained, is angled relative to the expandable stent graft <NUM>. For example, the collar <NUM> may form an acute angle (θ) with the expandable stent graft <NUM>. In some embodiments, the acute angle θ is between <NUM>° and <NUM>°, between <NUM>° and <NUM>°, and/or between <NUM>° and <NUM>°. The angle relationship between the collar <NUM> and the expandable stent graft <NUM> may facilitate positioning of the collar <NUM> to function as a seal. For example, as shown in <FIG>, the deployed collar <NUM> may function as a seal, thereby preventing or reducing the leakage of blood from the opening in the arteriovenous graft <NUM> or artery into which the expandable stent graft <NUM> has been inserted. The collar <NUM> may also prevent or reduce the risk of withdrawal of the expandable stent graft <NUM> from the arteriovenous graft <NUM> or the artery. Stated differently, the collar <NUM> may serve as a stop that prevents withdrawal of the expandable stent graft <NUM> from the arteriovenous graft <NUM> or the artery.

During placement and/or implantation of vascular access assemblies, such as those describe above, various strategies may be employed to reduce or prevent the loss of blood. For example, in some embodiments, various clamps are used during implantation to restrict fluid flow through a portion of the first tubular conduit and/or the second tubular conduit. In other or further embodiments, the first tubular conduit and/or the second tubular conduit include one of more valves that obstruct fluid flow, thereby preventing the loss of blood during implantation. For example, in some embodiments, a valve is disposed adjacent the peripheral end of the first tubular conduit or the central end of the second tubular conduit. The valve may be configured to transition from a first configuration that prevents fluid flow through the valve when the first tubular conduit and the second tubular conduit are uncoupled from each other to a second configuration that allows fluid flow through the valve when the first tubular conduit and the second tubular conduit are coupled to each other. In some embodiments, fluid flow is restricted by a balloon that is disposed within a portion of the vascular access assembly.

Kits that include a vascular access assembly are also within the scope of this disclosure. For example, a kit may include any of the vascular access assemblies described above. The kit may also include other elements, such as instructions for using the vascular access assembly to establish a flow path from an artery or an arteriovenous graft of a patient to a heart of the patient. Kits may additionally or alternatively include (<NUM>) one or more clamps for preventing fluid flow through a portion of a tubular conduit, (<NUM>) scissors, (<NUM>) plugs for preventing fluid flow through an end of a tubular conduit, (<NUM>) a tunneling device, (<NUM>) a syringe, (<NUM>) one or more guidewires, (<NUM>) gauze pads, (<NUM>) contrast fluid, and/or (<NUM>) saline (e.g., heparinized saline), among other potential elements.

Any methods disclosed herein include one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. Moreover, sub-routines or only a portion of a method described herein may be a separate method within the scope of this disclosure. Stated otherwise, some methods may include only a portion of the steps described in a more detailed method.

Similarly, it should be appreciated by one of skill in the art with the benefit of this disclosure that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim requires more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims.

Claim 1:
A vascular access assembly (<NUM>; <NUM>; <NUM>) comprising:
a first tubular conduit (<NUM>);
a second tubular conduit (<NUM>);
an expandable stent graft (<NUM>; <NUM>; <NUM>) that is coupled to the second tubular conduit (<NUM>) adjacent a peripheral end of the second tubular conduit (<NUM>), wherein the expandable stent graft (<NUM>; <NUM>; <NUM>) includes a first branch configured to couple to an artery, vein or arteriovenous graft of a patient such that the first branch permits blood flow through the artery, vein, or arteriovenous graft, wherein the expandable stent graft (<NUM>; <NUM>; <NUM>) includes a second branch coupled to the second tubular conduit (<NUM>) such that the artery, the vein, or the arteriovenous graft is in fluid communication with the second tubular conduit (<NUM>); and
a restraint comprising a pull string (<NUM>) coupled to filaments surrounding the expandable stent graft in a compressed state;
wherein the first tubular conduit (<NUM>) is configured to couple to a central end of the second tubular conduit (<NUM>) to form a flow path that extends from the artery, the vein, or the arteriovenous graft to a heart of the patient.