Patent Description:
Medical catheters may be used in various medical procedures. For example, a medical catheter may be used to transport a fluid such as a drug or a medical agent (e.g., an embolic substance) to a target site within a patient. Additionally, or alternatively, a medical catheter may be used to transport an insertable or implantable medical device, a guidewire, or the like to a target site within a patient. <CIT> discloses an endoluminal catheterization device. <CIT> discloses a stent delivery balloon catheter system. <CIT> discloses an endovascular valve device. <CIT> discloses a catheter system includes an inflatable structural balloon and collapsible filter.

Further aspects are defined in dependent claims <NUM>-<NUM>. In some examples, this disclosure describes catheters that include an elongated body, an expandable member, and a retainer configured to hold the expandable member in a collapsed configuration. The expandable member is configured to expand radially outward away from the elongated body from a collapsed configuration to an expanded configuration while a first end of the expandable member is mechanically connected to the elongated body. The retainer may be configured to overlap a second end of the expandable member to hold the expandable member in the collapsed configuration. The expandable member may be configured to contact the inner walls of a vessel of a patient when the expandable member is in the expanded configuration. In some examples, expandable member may be configured to deflect a portion of the elongated body distal to the expandable member when the expandable member contacts the inner walls of the vessel. In this way, the expandable member may aid navigation of the catheter through vasculature of a patient.

In some examples, the catheter further may include an occlusive material attached to the expandable member and configured to unfold or expand with the expandable member from a folded or collapsed configuration to an unfolded or expanded configuration that approximates the expanded configuration of the expandable member. When in the respective unfolded and/or expanded configurations, the occlusive material and the expandable member may be configured to provide a flow barrier to reduce or prevent antegrade blood flow within the vessel and/or to reduce or prevent retrograde flow of a fluid from the target vessel to a feeding vessel.

Other features, objects, and advantages of the systems and techniques described in this disclosure will be apparent from the description and drawings, and from the claims.

In examples described herein, a catheter includes an elongated body, an expandable member mechanically connected at a first end to the elongated body, and a retainer configured to releasably retain the expandable member in a collapsed configuration. Catheters as described herein may be configured for navigation through vasculature of a patient to facilitate the delivery of a therapeutic substance or a medical device to a target site within the patient, the aspiration of material from a blood vessel or other anatomical structure of a patient, and/or occlusion of a blood vessel of the patient. The expandable member of such catheters may be configured to expand radially outward away from the elongated body from the collapsed configuration to an expanded configuration when a second end of the expandable member (e.g., opposite the first end) is released by the retainer while the first end remains mechanically coupled to the elongated body.

An expandable member of a catheter described herein may act as a navigation structure that helps a user navigate the catheter through vasculature, e.g., by enabling deflection of the elongated body within vasculature when the expandable member is in the expanded configuration. As further described below, in some examples, an occlusive material may be connected to the expandable member. When the expandable member is expanded in these examples, the occlusive material may provide a flow barrier to reduce or prevent antegrade blood flow within a vessel and/or reduce or prevent retrograde flow of a fluid (e.g., an embolic substance) introduced into a target vessel, from the target vessel to an undesired location such as a feeding vessel.

The expandable members described herein may be configured to self-expand from a collapsed configuration to an expanded configuration. For example, the expandable member may be formed from a shape-memory material (e.g., Nitinol) in a stent-like or mesh-like configuration. In other examples, the expandable member may not necessarily be self-expandable and may be expanded with the aid of, for example, a balloon or another expandable structure.

The retainer is configured to hold the expandable member in a collapsed configuration by overlapping the second end of the expandable member. The retainer is expandable to release the second end of the expandable member, thereby enabling the expandable member to expand from the collapsed configuration to the expanded configuration. In some such examples, the elongated body may define a lumen and an outer wall that defines at least one opening fluidically connecting the lumen and the retainer to enable an inflation fluid (e.g., saline) to be introduced into the retainer. An end of the retainer that does not overlap the second end of the expandable member (e.g., an end of the retainer furthest from the second end of the expandable member) may be mechanically coupled to the elongated body of the catheter. The retainer may be expandable to release the second end of the expandable member when an inflation fluid is introduced into the retainer via the lumen and the at least one opening. As the retainer expands, the retainer may move away from the expandable member such that the retainer does not overlap the second end of the expandable member, thereby releasing the expandable member and enabling the expandable member to expand radially outward from the elongated body from the collapsed configuration to the expanded configuration. In the expanded state, the first end of the expandable member may remain connected to the elongated member while the second end of the expandable member is spaced from the elongated member in a radial direction.

In other examples, the retainer can be configured to release the second end of the expandable member using another technique. For example, the elongated body may include an inner member and an outer member, and the expandable member may be mechanically connected to the outer member and the retainer may be mechanically connected to the inner member. Longitudinal movement of the inner member relative to the outer member moves the retainer relative to the expandable member, thereby releasing the second end of the expandable member from the retainer and enabling the expandable member to expand from the collapsed configuration to the expanded configuration. In these examples, the retainer may not be expandable.

In any such examples, the expandable member may be configured to engage with a vessel wall of a patient when the expandable member is in the expanded configuration, which may help a clinician navigate the catheter through vasculature by deflecting the elongated body when the expandable member is in the expanded configuration. For example, contact between the expandable member and the vessel wall may enable deflection of the elongated body during navigation of the catheter through the vasculature to a treatment site when a distal (i.e., leading) portion of the catheter encounters a curved portion of the vessel. As an example, a clinician may advance the catheter through a blood vessel until the expandable member is positioned within the curved portion of the vessel or proximal to the curved portion. The clinician then may release the second end of the expandable member from the retainer to expand the expandable member, such as by expanding the retainer or moving an inner member of the elongated body to move the retainer relative to the expandable member and release the second end of the expandable member from the retainer. The expandable member expands into contact with the curved portion of the vessel, and contact between the expandable member and the curved portion of the vessel may cause deflection of a portion of elongated body distal to the expandable member into a curved or bent configuration that better approximates the curved shape of the vessel than a straight elongated body configuration. With the elongated body in such a curved or bent configuration, the clinician may advance the elongated body through the curved portion of the vessel more readily relative to when the elongated body is in a linear configuration.

In some examples, the catheter further may include a layer of occlusive material that is attached to the expandable member and configured to at least partially cover (e.g., fully cover or partially cover) the expandable member when the expandable member is in the expanded configuration. The occlusive material may be a flexible, substantially fluid-impermeable (e.g., fluid impermeable but for weep holes that are configured to help prevent air pockets) material such as a polymer. The expandable member and the layer of occlusive material together may help prevent retrograde flow of a substance (e.g., an embolic substance) introduced into a vessel during a medical procedure past the expandable member and/or may provide a temporary vessel-occlusion device by reducing or preventing antegrade blood flow. For example, the layer of occlusive material and the expandable member may be configured to reduce or prevent antegrade blood flow within a vessel of a patient when the layer of occlusive material and the expandable member are in the expanded configuration and the expandable member is engaged with a vessel wall. In some examples, the expandable member may define a funnel shape when in the expanded configuration, with a mouth of the funnel facing in either a proximal or a distal direction relative to the elongated body. Regardless of the direction a mouth of such a funnel, the retainer may be configured to overlap the end of the expandable member that defines the funnel when the retainer is holding the expandable member in the collapsed configuration.

The retainers described herein may reduce or eliminate a need to include an additional sheath in a catheter to retain an expandable member in a collapsed configuration, thereby enabling an elongated body of a catheter to have a relatively larger diameter relative to other example catheters in which an additional sheath is used to retain an expandable member. Thus, the example retainers described herein may enable an elongated body of a catheter to define a relatively larger working channel that may be used in a medical procedure, such as for aspiration of a fluid and/or delivery of a medical device or fluid.

Other proposed methods of preventing retrograde flow of embolic substance from a target vessel into a primary feeding vessel include first casting a liquid embolic substance to form a plug at a tip of a delivery catheter and then delivering additional embolic substance to fill the target vessel. This process may reduce or prevent retrograde flow of the embolic substance but may be relatively time consuming compared to the use of an expandable member and occlusive material described herein. In other examples, a dual-lumen balloon may be used as a backstop while injecting an embolic substance into the target vessel. This option also may reduce or prevent retrograde flow but can add complexity to the procedure and may involve a possibility of balloon rupture due to over-inflation of the balloon.

This disclosure describes examples of catheters having expandable members that may function as a backstop and/or steering member to help increase the efficiency and/or improve clinical outcomes of vascular treatment procedures. For example, an expandable member and layer of occlusive material, as described herein, may reduce the amount of time needed to treat a vessel with an embolic substance by reducing or eliminating need for casting a plug of embolic substance at a tip of a delivery catheter, and/or reducing or eliminating need for a balloon backstop. Additionally, or alternatively, the steerability provided to the catheter by an expandable member and a retaining member, as described herein, may reduce the amount of time needed to navigate the catheter through curved portions of the patient's vasculature to reach a target vessel. Thus, the example catheters described herein may provide one or more benefits over other catheters that may be used in vascular procedures.

While the present disclosure describes catheters primarily in the context of procedures for treating vascular conditions such as arteriovenous malformations (AVMs), the devices of the present disclosure may also be used in procedures to treat other vascular conditions or to access portions of a patient's vasculature for other purposes. For example, the catheters described herein may be used as temporary vessel occlusion devices for use in ischemic stroke interventional procedures (such as clot aspiration procedures or stentriever thrombectomy procedures) or as a backstop device during other neuro-interventional procedures.

<FIG> and <FIG> illustrate an example catheter <NUM>, which is configured to be navigated through vasculature of a patient and defines one or more lumens that facilitate the delivery of a therapeutic substance or a medical device to a target site within the patient, aspiration of material from a blood vessel or other part of a patient, and/or occlusion of a blood vessel of the patient. <FIG> is a schematic cross-sectional view of catheter <NUM>, where the cross-section is taken along a longitudinal axis <NUM> of catheter <NUM>. Longitudinal axis <NUM> may be a central longitudinal axis of one or more components of catheter <NUM>, such as an elongated body <NUM> of catheter <NUM>.

Elongated body <NUM> of catheter <NUM> extends from a proximal end <NUM> to a distal end <NUM>. In some examples, catheter <NUM> may include a strain relief member <NUM>. In such examples, proximal end <NUM> of elongated body <NUM> may be partially covered by strain relief member <NUM>, such that proximal end <NUM> of elongated body <NUM> may be more distal than as shown in <FIG>. Catheter <NUM> further includes an expandable member <NUM> that extends from a first (e.g., proximal) end <NUM> and a second (e.g., distal) end <NUM>. In the example of <FIG> and <FIG>, first end <NUM> of expandable member <NUM> is mechanically coupled to elongated body <NUM> either directly or indirectly (e.g., with a sleeve or another material positioned between first end <NUM> and elongated body <NUM>). For example, first end <NUM> of expandable member <NUM> may be bonded, crimped, swaged, welded, or otherwise secured to elongated body <NUM>. In <FIG>, expandable member <NUM> is in a collapsed configuration, in which expandable member <NUM> may be folded or rolled into a physically smaller radial profile than an expanded configuration of expandable member <NUM> illustrated in <FIG>. The general shape of the collapsed configuration of expandable member <NUM> shown in <FIG> is intended to be illustrative and not limiting. Other shapes and configurations of the collapsed configuration of expandable member <NUM> are also possible.

Expandable member <NUM> is configured to expand radially outward from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG>. For example, second end <NUM> of expandable member <NUM> may be configured to move radially outward relative to elongated body <NUM> to permit a portion of expandable member <NUM> including second end <NUM> to expand radially away from elongated body <NUM> while first end <NUM> remains mechanically coupled to elongated body <NUM>.

Dimensions of expandable member <NUM> and/or one or more other components of catheter <NUM> may be selected based on dimensions of one or more vessels of the patient. Expandable member <NUM> has a length "LEM" (measured parallel to longitudinal axis <NUM>) and a collapsed expandable member diameter "DEM1" measured orthogonal to longitudinal axis <NUM> when expandable member <NUM> is in the collapsed configuration. Length LEM and diameter DEM1 may be selected based on the desired properties for catheter <NUM>. In some examples, length LEM of expandable member <NUM> may be from about <NUM> millimeters (mm) to about <NUM> and collapsed expandable-member diameter DEM1 may be from about <NUM> to about <NUM>. Although DEM1 is described herein as being a diameter of expandable member <NUM>, in some examples, expandable member <NUM> may have a non-circular cross-sectional shape in the collapsed and/or expanded configurations in other examples. DEM1 may be any greatest dimension of expandable member <NUM> measured orthogonal to longitudinal axis <NUM> when expandable member <NUM> is in the collapsed configuration.

Expandable member <NUM> has any suitable configuration that enables it to be collapsed into a low-profile configuration for delivery and navigation through vasculature of a patient, and expand radially outward from collapsed diameter DEM1 to an expanded configuration (e.g., as shown in <FIG>) in which expandable member <NUM> may engage with a vessel wall of a patient, such as a target vessel to which a clinician may navigate catheter <NUM>. In the example shown in <FIG>, expandable member <NUM> may include a plurality of struts <NUM>. Struts <NUM> may define any suitable pattern and cell structure (e.g., open cells or closed cells), such as a serpentine, zig-zag, or accordion-like pattern. In other examples, struts <NUM> of expandable member <NUM> may have other configurations, such as one or more compressible coils. In other examples, expandable member <NUM> may include an expandable mesh material. In any such examples, expandable member <NUM> may be self-expandable (e.g., formed from nitinol or another shape-memory material).

In some examples, expandable member <NUM> may include a hydrophobic coating or a lubricious coating on one or more outer surfaces defined by expandable member <NUM>, which may help reduce or prevent sticking of expandable member <NUM> to some substances that may be delivered during a vascular interventional procedure, such as some embolic substances. In some examples, one or more components of expandable member <NUM> (e.g., struts <NUM>) may include markers, coatings, or jackets, formed from a material that may be visualized during fluoroscopy, such as platinum, or another suitable radiopaque material.

Catheter <NUM> further includes an expandable retainer <NUM> including a proximal portion <NUM> and a distal portion <NUM> distal to proximal portion <NUM>. In some examples, distal portion <NUM> of expandable retainer <NUM> is mechanically connected to elongated body <NUM> distal to second end <NUM> of expandable member <NUM>, such as by bonding, crimping, swaging, welding, or otherwise securing distal portion <NUM> of expandable retainer <NUM> to elongated body <NUM>. In <FIG>, expandable retainer <NUM> is in a collapsed configuration, in which expandable retainer <NUM> may be folded or rolled into a physically smaller profile than when in an expanded configuration illustrated in <FIG>. The general shape of the collapsed configuration of expandable retainer <NUM> shown in <FIG> is intended to be illustrative and not limiting. Other shapes and configurations of the collapsed configuration of expandable member <NUM> are also possible.

Expandable retainer <NUM> is configured to overlap second end <NUM> of expandable member <NUM> and retain expandable member <NUM> in the collapsed configuration, as illustrated in <FIG>. For example, proximal portion <NUM> of expandable retainer <NUM> may be configured to overlap a distal portion of expandable member <NUM> that includes second end <NUM> of expandable member <NUM>. Proximal portion <NUM> may have an overlap length "LOL" that defines the portion of expandable retainer <NUM> that overlaps expandable member <NUM>. In some examples, a ratio of overlap length LOL to length LEM of expandable member <NUM> may be about <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM> or <NUM>:<NUM>. However, the extent to which proximal portion <NUM> overlaps expandable member <NUM> may vary in other examples.

In the example shown in in <FIG> and <FIG>, expandable retainer <NUM> is configured to expand radially outward from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG>. Expandable retainer <NUM> has a length "LR" (measured parallel to longitudinal axis <NUM> when expandable retainer <NUM> is in the collapsed configuration) and a collapsed retainer diameter "DR1" (measured orthogonal to longitudinal axis <NUM>) when retainer <NUM> is in the collapsed configuration. Length LR may be from about <NUM> to about <NUM>. Collapsed retainer diameter DR1 may be from about <NUM> to about <NUM>. Although DR1 is described herein as being a diameter of expandable retainer <NUM>, in some examples, expandable retainer <NUM> may have a non-circular cross-sectional shape, such that DR1 may be any greatest dimension of expandable retainer <NUM> measured orthogonal to longitudinal axis <NUM> when expandable retainer <NUM> is in the collapsed configuration. For example, proximal portion <NUM> of expandable retainer <NUM>, which overlaps the distal portion of expandable member <NUM> that includes second end <NUM>, may have a non-circular cross-sectional shape.

In some examples, proximal portion <NUM> of expandable retainer <NUM> may comprise two or more tabs defining spaces therebetween. The force with which expandable retainer <NUM> retains expandable member <NUM> in the collapsed configuration may be varied by varying the dimensions or number of the tabs of proximal portion <NUM> and/or the spaces defined by the tabs of proximal portion <NUM>. According to the invention, expandable retainer <NUM> is configured as a balloon.

Elongated body <NUM> defines a lumen <NUM>, an optional valve <NUM>, and an outer wall <NUM>. In examples in which distal end <NUM> of elongated body <NUM> defines an opening, elongated body <NUM> may include valve <NUM>, which is configured to block the flow of inflation fluid introduced into lumen <NUM> from exiting distal end <NUM> of elongated body <NUM>. Valve <NUM> may extend radially inward from outer wall <NUM> into lumen <NUM>. In other examples, elongated body <NUM> may define one or more additional lumens (not shown) in addition to lumen <NUM>. Such additional lumens may be used to aspirate fluid and/or deliver a drug or medical agent to a vessel. In such examples, lumen <NUM> may be an inflation lumen that does not define a distal opening and, therefore, may not include valve <NUM>. Outer wall <NUM> may define at least one opening that fluidically connects lumen <NUM> and expandable retainer <NUM>. For example, outer wall <NUM> may define two openings, 42A and 42B, as illustrated in <FIG>. In some examples, catheter <NUM> further may include a hub <NUM> positioned at proximal end <NUM> of elongated body <NUM>. In such examples, lumen <NUM> may extend longitudinally through elongated body <NUM> at least from openings 42A, 42B to hub <NUM>. Hub <NUM> may include at least one of a first port <NUM> or a second port <NUM>, one or both of which may be in fluid communication with lumen <NUM>. Lumen <NUM> is configured to receive a fluid that is introduced into the lumen <NUM> via hub <NUM> to expand or inflate expandable retainer <NUM> (e.g., once catheter <NUM> has been navigated to a target site in the vessel).

Expandable retainer <NUM> may be formed from any suitable material that provides sufficient strength and flexibility to withstand the pressures exerted on expandable retainer <NUM> during a medical procedure. The materials from which the expandable retainer <NUM> is formed may be biocompatible with patient tissue. In some examples, materials from which expandable retainer <NUM> is formed may include nylon, polyethylene terephthalate (PET), polyethylene (such as crosslinked polyethylene), expanded polytetrafluoroethylene (ePTFE), polyurethane, polyvinyl chloride, silicone elastomer, or the like. The material of expandable retainer <NUM> may have sufficient elasticity to enable expandable retainer <NUM> to expand to the expanded configuration and thereafter to collapse to a smaller diameter (e.g., substantially to collapsed retainer diameter RD1) when the fluid used to expand expandable retainer <NUM> is aspirated from expandable retainer <NUM> or otherwise exits expandable retainer <NUM>. For example, fluid used to expand expandable retainer <NUM> may be aspirated from expandable retainer <NUM> after expanding expandable member <NUM> to deflect a portion of elongated body <NUM> distal to expandable member <NUM> and prior to continuing to advance catheter <NUM> to a treatment site and/or prior to aspirating a portion of catheter <NUM> including expandable retainer <NUM> into an outer sheath (not shown). Expandable retainer <NUM> may be made by any suitable technique, such as by molding, or extrusion, or other manufacturing techniques.

<FIG> is a schematic cross-sectional view of catheter <NUM> of <FIG> with expandable member <NUM> in the expanded configuration and released from expandable retainer <NUM>, where the cross-section is taken along longitudinal axis <NUM> of catheter <NUM>. <FIG> illustrates catheter <NUM> after a fluid has been introduced into expandable retainer <NUM>, via lumen <NUM> and openings 42A, 42B, to expand expandable retainer <NUM>. As expandable retainer <NUM> expands, a diameter of expandable retainer <NUM> increases from collapsed expandable-retainer diameter DR1 to a larger expanded retainer diameter "DR2" of the expanded configuration of expandable retainer <NUM>. Larger expanded retainer diameter DR2 may be from about <NUM> to about <NUM>. Thus, larger expanded retainer diameter DR2 may be smaller than a larger expandable member diameter "DEM2. " As expandable retainer <NUM> expands, the proximal portion of expandable retainer <NUM> that overlaps second end <NUM> of expandable member <NUM> releases second end <NUM>, which enables expandable member <NUM> to expand radially outward (e.g., self-expand) from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG>. Additionally, or alternatively, expandable member <NUM> may be expandable via actuation of a push/pull wire attached to expandable member <NUM> (not shown), or any other suitable feature configured to expand and/or collapse expandable member <NUM>.

In the expanded configuration, expandable member <NUM> defines a larger expandable-member diameter "DEM2" compared to the collapsed expandable-member diameter DEM1. Expandable member <NUM> may define diameter DEM2 at least at second end <NUM> of expandable member <NUM>. Expandable-member diameter DEM2 may be from about <NUM> to about <NUM>. In some examples, expandable member diameter DEM2 may correspond to an inner diameter of a vessel of a patient into which catheter <NUM> may be introduced, as self-expansion of expandable member <NUM> within a lumen defined by the vessel of the patient may bring expandable member <NUM> into contact with an inner surface of the vessel. Because expanded retainer diameter DR2 of expandable retainer <NUM> may be smaller than larger expandable-member diameter DEM2, expandable retainer <NUM> is not necessarily configured to contact the inner surface of the vessel when expandable retainer <NUM> is in the expanded configuration. In this manner, the configuration of expandable retainer <NUM> advantageously may reduce or eliminate a possibility of vessel rupture due to over-inflation of the balloon against an inner surface defined by the vessel.

Additionally, or alternatively, expandable retainer <NUM> may reduce or eliminate a need to include an additional sheath in catheter <NUM> to retain expandable member <NUM> in the collapsed configuration. In this manner, expandable retainer <NUM> may enable elongated body <NUM> to define a relatively larger diameter for a given target vessel, thereby enlarging lumen <NUM> (e.g., relative to other catheters that may include an additional sheath). Thus, lumen <NUM> may define a relatively larger working channel that may be used in a medical procedure using catheter <NUM>.

Expandable member <NUM> may contact and engage with the inner surface of the vessel (e.g., as shown in <FIG> and described with respect thereto) when in an expanded state, which may cause a portion of elongated body <NUM> distal to first end <NUM> of expandable member <NUM> to deflect relative to a central longitudinal axis of a more proximal portion of elongated body <NUM>. Thus, at least a portion of elongated body <NUM> distal to expandable member <NUM> may better conform to a curved shape of a vessel of a patient, deflect to better center itself within the vessel, and/or pivot within the vessel when expandable member <NUM> is in the expanded configuration. In this manner, expandable member <NUM> may help a user navigate catheter <NUM> through vasculature by enabling deflection of elongated body <NUM> when expandable member <NUM> is expanded from the collapsed configuration to the expanded configuration at a curved portion of a vessel through which catheter <NUM> is navigated, as further described below with respect to <FIG>.

The presence of expandable member <NUM> on elongated body <NUM> may increase the flexural stiffness of catheter <NUM> at that location on elongated body <NUM>. Connecting first end <NUM> of expandable member <NUM> to elongated body <NUM> closer to proximal end <NUM> of elongated body <NUM> than distal end <NUM> may enable a distal portion (distal to expandable member <NUM>) of elongated body <NUM> to be more flexible yet still aid navigation of elongated body <NUM> into distal vasculatures.

In some examples, second end <NUM> of expandable member <NUM> may be about <NUM> to about <NUM> proximal to distal end <NUM> of elongated body <NUM>, although second end <NUM> of expandable member <NUM> may be positioned closer to distal end <NUM> or further from distal end <NUM> in other examples. For example, second end <NUM> of expandable member <NUM> may be more than about <NUM> to about <NUM> proximal to distal end <NUM> of elongated body <NUM> when blocking antegrade blood flow toward a captured clot during a medical procedure using A Direct Aspiration first Pass Technique (ADAPT) for acute stroke thrombectomy, or any other aspiration or removal of thrombus or other material from the neurovasculature or other blood vessels. The clot may be suctioned at distal end <NUM> of elongated body <NUM>, and blocking antegrade blood flow toward the captured clot may help prevent antegrade blood flow from breaking up the captured clot or opposing or disrupting the suction applied to the clot. In this manner, restriction of blood flow provided relatively closer to proximal end <NUM> of elongated body <NUM> may improve an outcome of an aspiration procedure in which blocking antegrade blood flow may be desirable. In some such examples, expandable member <NUM> may remain in the expanded configuration until at least a portion of catheter <NUM> including expandable member <NUM> is aspirated into an outer sheath (not shown).

As illustrated in <FIG>, in some examples, expandable member <NUM> may define a funnel shape when in the expanded configuration. The funnel shape may help expandable member <NUM> reduce retrograde flow of a substance (e.g., an embolic substance) through vasculature (e.g., into a parent vessel) when in the expanded configuration by providing a framework to which occlusive material (not shown) may attach, which in combination with expandable member <NUM> may prevent backflow of the introduced substance. Examples of occlusive material that may be attached to expandable member <NUM> are discussed below with respect to <FIG>.

In examples in which expandable member <NUM> defines a funnel shape, a diameter of expandable member <NUM> may taper from expanded diameter DEM2 at second end <NUM> of expandable member <NUM> to a diameter "DEM3" at first end <NUM> of expandable member <NUM>, such that a mouth of the funnel defined by expandable member <NUM> faces a distal direction (e.g., toward distal end <NUM> of elongated body <NUM>). Diameter DEM3 may be substantially similar to diameter DEM1 of expandable member <NUM> when expandable member <NUM> is in the collapsed configuration. That is, in some examples in which expandable member <NUM> defines a funnel shape when in the expanded configuration, a proximal portion of expandable member <NUM> that includes first end <NUM> may not expand substantially from DEM1, although the dimensions of expandable member <NUM> may be adapted to dimensions of a target vessel or a technique in which catheter <NUM> may be used.

Additionally, or alternatively, a mouth of a funnel defined by expandable member <NUM> that faces in a distal direction, as shown in <FIG> and <FIG>, may enable expandable member <NUM> to reduce or prevent pooling of blood within expandable member <NUM> during a procedure in which expandable member acts as a backstop against retrograde flow of a substance introduced into a target vessel. For example, catheter <NUM> may further include a layer of occlusive material (not shown), which may be formed of a substantially fluid-impermeable (e.g., fluid impermeable but for weep holes that are configured to help prevent air pockets) material and which in combination with expandable member <NUM> may prevent backflow of a substance (e.g., an embolic substance) introduced into a target vessel to reduce or prevent retrograde flow of the introduced substance from the target vessel into a parent vessel that may be located proximal of expandable member <NUM>. Catheter <NUM> may be introduced into a vessel of a patient with the flow of blood, such that blood flows from first end <NUM> of expandable member <NUM> toward second end <NUM> of expandable member <NUM>. Thus, connecting first end <NUM> of expandable member <NUM> to elongated body <NUM> such that a mouth of a funnel defined by expandable member <NUM> when expandable member <NUM> is in the expanded configuration may enable blood to flow against expandable member <NUM> substantially without pooling within expandable member <NUM>. In some examples, reducing or eliminating pooling of blood within an expandable member configured to temporarily occlude the vessel may provide one or more advantages. For example, pooling of blood may cause stasis that can initiate a clotting cascade that can later embolize when withdrawing catheter <NUM> into an outer sheath for withdrawal from the patient.

<FIG> and <FIG> illustrate another example catheter <NUM> that includes an expandable member <NUM> and a retainer <NUM> configured to hold the expandable member in a collapsed configuration. Catheter <NUM> is similar to catheter <NUM> shown in <FIG> and <FIG>, except that the expandable member <NUM> faces in an opposite direction than expandable member <NUM> of catheter <NUM>. <FIG> and <FIG> are schematic cross-sectional view of catheter <NUM>, where the cross-section is taken along a longitudinal axis <NUM> of catheter <NUM>. Longitudinal axis <NUM> may be a central longitudinal axis of one or more components of catheter <NUM>, such as an elongated body <NUM> of catheter <NUM>.

Elongated body <NUM> of catheter <NUM> extends from a proximal end <NUM> to a distal end <NUM>. Catheter <NUM> further includes an expandable member <NUM> that extends from a first (e.g., distal) end <NUM> to a second (e.g., proximal) end <NUM>. In the example of <FIG> and <FIG>, first end <NUM> of expandable member <NUM> is mechanically coupled to elongated body <NUM> either directly or indirectly (e.g., with a sleeve or another material positioned between first end <NUM> and elongated body <NUM>). For example, first end <NUM> of expandable member <NUM> may be bonded, crimped, swaged, welded, or otherwise secured to elongated body <NUM>. Expandable member <NUM> can be generally similar to expandable member <NUM> and may include a plurality of struts <NUM> or an expandable mesh material. As illustrated in <FIG>, expandable member <NUM> may be expandable from collapsed diameter DEM1 to the expanded configuration in which expandable member <NUM> may engage with a vessel wall of a patient, such as a target vessel to which a clinician may navigate catheter <NUM>.

Catheter <NUM> further includes an expandable retainer <NUM> extending from a proximal portion <NUM> to a distal portion <NUM>. Expandable retainer <NUM> can be generally similar to expandable retainer <NUM>, except expandable retainer <NUM> can be configured to retain a proximal end of an expandable member (<NUM>). In some examples, proximal portion <NUM> of expandable retainer <NUM> is mechanically connected to elongated body <NUM> proximal to second end <NUM> of expandable member <NUM>, such as by bonding, crimping, swaging, welding, or otherwise securing proximal portion <NUM> of expandable retainer <NUM> to elongated body <NUM>. Distal portion <NUM> of expandable retainer <NUM> is configured to overlap second end <NUM> of expandable member <NUM> and retain expandable member <NUM> in the collapsed configuration, as illustrated in <FIG>. For example, distal portion <NUM> of expandable retainer <NUM> is configured to overlap a proximal portion of expandable member <NUM> that includes second end <NUM> of expandable member <NUM>. Distal portion <NUM> may have an overlap length "OLL" that defines the portion of expandable retainer <NUM> that overlaps expandable member <NUM>.

Elongated body <NUM> defines a lumen <NUM>, a valve <NUM>, and an outer wall <NUM>. In examples in which distal end <NUM> of elongated body <NUM> defines an opening, elongated body <NUM> may include valve <NUM>, which may extend radially inward from outer wall <NUM> into lumen <NUM>. In such examples, valve <NUM> may help prevent inflation fluid introduced into lumen <NUM> from exiting distal end <NUM> of elongated body <NUM>. In other examples, elongated body <NUM> may define one or more additional lumens (not shown) in addition to lumen <NUM>. Such additional lumens may be used to aspirate fluid and/or deliver a drug or medical agent to a vessel. In such examples, lumen <NUM> may not necessarily define a distal opening and may not necessarily include valve <NUM>. Outer wall <NUM> may define at least one opening that fluidically connects lumen <NUM> and expandable retainer <NUM>. For example, outer wall <NUM> may define two openings, 82A and 82B, as illustrated in <FIG>. In some examples, catheter <NUM> further may include a hub <NUM> positioned at proximal end <NUM> of elongated body <NUM>. Hub <NUM> may include at least one of a first port <NUM> or a second port <NUM>, one or both of which may be in fluid communication with lumen <NUM>.

<FIG> is a schematic cross-sectional view of catheter <NUM> of <FIG> with expandable member <NUM> in the expanded configuration and released from expandable retainer <NUM>, where the cross-section is taken along longitudinal axis <NUM> of catheter <NUM>. <FIG> illustrates catheter <NUM> after a fluid has been introduced into expandable retainer <NUM>, via lumen <NUM> and openings 82A, 82B, to expand expandable retainer <NUM> radially outward. As expandable retainer <NUM> releases second end <NUM> of expandable member <NUM>, expandable member <NUM> expands radially outward from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG> while first end <NUM> remains mechanically coupled to elongated body <NUM>.

One or more features of catheter <NUM> of <FIG> and <FIG> may be substantially similar to the corresponding features of catheter <NUM> described above with respect to <FIG> and <FIG> and will not be discussed again in detail here. For example, elongated body <NUM>, expandable member <NUM>, expandable retainer <NUM>, and hub <NUM> may be substantially similar to elongated body <NUM>, expandable member <NUM>, expandable retainer <NUM>, and hub <NUM> of catheter <NUM>, respectively. As another example, distal portion <NUM> of expandable retainer <NUM> is configured to release second end <NUM> of expandable member <NUM> when a fluid has been introduced, via lumen <NUM> and openings 82A, 82B, to expand expandable retainer <NUM> to the expanded configuration illustrated in <FIG>, in a manner substantially similar to the manner in which expandable member <NUM> is configured to release second end <NUM> of expandable member <NUM>. As with catheter <NUM>, a ratio of overlap length LOL of distal portion <NUM> of expandable retainer <NUM> to length EML of expandable member <NUM> may be about <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM> or <NUM>:<NUM>, although the extent to which distal portion <NUM> of expandable retainer <NUM> overlaps expandable member <NUM> may vary in other examples.

Catheter <NUM> may differ from catheter <NUM> in that first end <NUM> of expandable member <NUM>, which is mechanically connected to elongated body <NUM>, is distal to second end <NUM> of expandable member <NUM> instead of being proximal to second end <NUM>. Catheter <NUM> further may differ from catheter <NUM> in that distal portion <NUM> of expandable retainer <NUM> is configured to overlap first end <NUM> of expandable member <NUM> instead of proximal portion <NUM> being configured to overlap first end <NUM> of expandable member <NUM> when expandable member <NUM> is retained by expandable retainer <NUM> in the collapsed configuration. Thus, distal portion <NUM> of expandable retainer <NUM> may comprise two or more tabs defining spaces therebetween, as described above with respect to proximal portion <NUM> of expandable retainer <NUM>. Thus, in examples in which expandable member <NUM> defines a funnel shape when expandable member <NUM> is in the expanded configuration, as illustrated in <FIG>, catheter <NUM> may further differ from catheter <NUM> in that expandable member <NUM> defines a funnel shape in which a mouth of the funnel faces a proximal direction (e.g., toward proximal end <NUM> of elongated body <NUM>) instead of a distal direction.

Expandable member <NUM> that defines a funnel shape having a mouth facing in a proximal direction may, in some examples, enable the use of antegrade flow of blood to help expand expandable member <NUM>, such that expandable member <NUM> does need a lot of radial outward force to expand. Reducing the amount of radially outward force needed to expand expandable member <NUM> may enable expandable member <NUM> (or at least the expandable structures of expandable member <NUM>) to be thinner, which may reduce the overall profile of expandable member <NUM>. A lower profile expandable member <NUM> may further facilitate navigation of catheter <NUM> to certain target sites within the vasculature of a patient.

In some other examples, a retainer may be disengaged from an expandable member to permit the expandable member to expand using techniques other than inflation of an expandable retainer via introduction of an inflation fluid via a lumen defined by an expandable member, as described above with respect to the examples of catheter <NUM> of <FIG> and <FIG> and catheter <NUM> of <FIG> and <FIG>. For example, a retainer may be disengaged from an end of an expandable member via relative longitudinal movement of two portions of an elongated body of a catheter, one of which may be mechanically connected to the expandable member and the other of which may be mechanically connected to the retainer, as described below with respect to <FIG> and <FIG>. Regardless of a manner in which an expandable member is configured to be expanded or a number of ends of an expandable member that are mechanically connected to an elongated body of an catheter, the expandable members described herein may provide a flow barrier to reduce or prevent antegrade blood flow within a vessel, reduce or prevent retrograde flow of a fluid, and/or may act as a navigation structure that helps a user navigate the catheter through vasculature.

<FIG> and <FIG> illustrate another example catheter <NUM> that includes an expandable member <NUM> configured to provide a flow barrier to reduce or prevent antegrade blood flow within a vessel, reduce or prevent retrograde flow of a fluid, and/or may act as a navigation structure that helps a user navigate the catheter through vasculature. <FIG> and <FIG> are schematic cross-sectional views of catheter <NUM>, where the cross-section is taken along a longitudinal axis <NUM> of catheter <NUM>. Longitudinal axis <NUM> may be a central longitudinal axis of one or more components of catheter <NUM>, such as an elongated body <NUM> of catheter <NUM>.

Elongated body <NUM> of catheter <NUM> includes an outer member <NUM>, which extends from a proximal end <NUM> to a distal end <NUM> and defines a lumen <NUM>. Elongated body <NUM> further includes an inner member <NUM> extending from a proximal end <NUM> to a distal end <NUM> and at least partially received within lumen <NUM> defined by outer member <NUM>. Inner member <NUM> may be slidably received within outer member lumen <NUM> such that inner member <NUM> is longitudinally movable relative to outer member <NUM>. As shown in <FIG>, proximal end <NUM> of inner member <NUM> may extend proximally of proximal end <NUM> of outer member <NUM>. Inner member <NUM> is configured to be grasped by a clinician at or near proximal end <NUM> (e.g., either directly or indirectly via a handle, hub, or the like) to move inner member <NUM> longitudinally relative to outer member <NUM>.

In some examples, outer member <NUM> and inner member <NUM> may be threadably connected such that inner member <NUM> and outer member <NUM> may be rotated relative to one another in order to move outer member <NUM> and inner member <NUM> longitudinally relative to each other. In some examples, inner member <NUM> and outer member <NUM> may be threadably connected via a threaded connection provided by external handles respectively coupled to outer member <NUM> and inner member <NUM>, or via an internal threaded connection. In this manner, longitudinal movement of inner member <NUM> relative to outer member <NUM> may be controlled via rotation of inner member <NUM> relative to outer member <NUM>. Control of longitudinal movement of inner member <NUM> relative to outer member <NUM> via relative rotation of inner member <NUM> and outer member <NUM> may enable the longitudinal positions of inner member <NUM> and outer member <NUM> to be more tightly controlled relative to examples in which an inner member and an outer member are configured to longitudinally slide freely relative to each other. Additionally, or alternatively, a threaded connection between inner member <NUM> and outer member <NUM> may keep inner member <NUM> and outer member <NUM> longitudinally fixed relative to one another when the not being rotated. Although the foregoing example is described with respect to movement of inner member <NUM> relative to outer member <NUM>, longitudinal movement of outer member <NUM> relative to inner member <NUM> may be controlled in a substantially similar manner.

Expandable member <NUM> extends from a first (e.g., proximal) end <NUM> to a second (e.g., distal) end <NUM>. In the example of <FIG> and <FIG>, first end <NUM> of expandable member <NUM> is mechanically coupled to outer member <NUM> of elongated body <NUM> either directly or indirectly (e.g., with a sleeve or another material positioned between second end <NUM> and outer member <NUM>). For example, first end <NUM> of expandable member <NUM> may be bonded, crimped, swaged, welded, or otherwise secured to outer member <NUM>. Expandable member <NUM> may be similar to expandable member <NUM> and may include a plurality of struts <NUM> or an expandable mesh material. As illustrated in <FIG>, expandable member <NUM> is configured to be expanded from collapsed configuration in which expandable member <NUM> defines diameter DEM1 to an expanded configuration in which expandable member <NUM> defines a larger diameter. In the expanded configuration, expandable member <NUM> may engage with a vessel wall of a patient, e.g., expandable member <NUM> may contact the vessel walls to block fluid flow past expandable member <NUM> and/or to deflect or otherwise change an orientation of a portion of catheter <NUM> distal to expandable member <NUM>.

Catheter <NUM> further includes a retainer <NUM> extending from a proximal portion <NUM> to a distal portion <NUM>. As illustrated in <FIG>, distal portion <NUM> of retainer <NUM> is mechanically connected to a portion of inner member <NUM> that extends distally of distal second end <NUM> of expandable member <NUM>, such as by bonding, crimping, swaging, welding, or otherwise securing distal portion <NUM> of retainer <NUM> to inner member <NUM>. Retainer <NUM> is configured to overlap second end <NUM> of expandable member <NUM> and retain expandable member <NUM> in the collapsed configuration, as illustrated in <FIG>. For example, proximal portion <NUM> of retainer <NUM> is configured to overlap a distal portion of expandable member <NUM> that includes second end <NUM> of expandable member <NUM>. Proximal portion <NUM> may have an overlap length "OLL" that defines the portion of expandable retainer <NUM> that overlaps expandable member <NUM>.

In some examples, catheter <NUM> further may include a hub <NUM> positioned at proximal end <NUM> of outer member <NUM>. Hub <NUM> may include at least one of a first port <NUM> or a second port <NUM>, one or both of which may provide access to lumen <NUM> defined by outer member <NUM> and/or a lumen defined by inner member <NUM> in examples in which inner member <NUM> defines a lumen (e.g., through which a substance may be delivered to, or aspirated from, a vessel of a patient.

<FIG> is a schematic cross-sectional view of catheter <NUM> of <FIG> with expandable member <NUM> in the expanded configuration and released from retainer <NUM>, where the cross-section is taken along longitudinal axis <NUM> of catheter <NUM>. <FIG> illustrates catheter <NUM> after inner member <NUM> has been moved distally, relative to outer member <NUM>, until proximal portion <NUM> of retainer <NUM> no longer overlaps second end <NUM> of expandable member <NUM>, thereby releasing second end <NUM> of expandable member <NUM>. After retainer <NUM> releases second end <NUM> of expandable member <NUM>, expandable member <NUM> can expand (e.g., self-expand) radially outward from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG> while first end <NUM> remains mechanically coupled to elongated body <NUM>.

One or more features of catheter <NUM> of <FIG> and <FIG> may be substantially similar to the corresponding features of catheter <NUM> described above with respect to <FIG> and <FIG> (or catheter <NUM> of <FIG> and <FIG>) and will not be discussed again in detail here. For example, expandable member <NUM> and hub <NUM> may be substantially similar to expandable member <NUM> and hub <NUM> of catheter <NUM>, respectively. Retainer <NUM> may be similar to expandable retainer <NUM> of catheter <NUM> in one or more aspects. For example, retainer <NUM> may be formed from one or more biocompatible materials from which expandable retainer <NUM> may be formed, such as nylon, polyethylene terephthalate (PET), polyethylene (such as crosslinked polyethylene), polyurethane, polyvinyl chloride, silicone elastomer, or the like. Proximal portion <NUM> of retainer <NUM> may comprise two or more tabs defining spaces therebetween, as described above with respect to proximal portion <NUM> of expandable retainer <NUM>.

In some examples, the configuration of retainer <NUM> when proximal portion <NUM> of retainer <NUM> overlaps second end <NUM> of expandable member <NUM> and retains expandable member <NUM> in the collapsed configuration may be substantially similar to the configuration of expandable retainer <NUM> when expandable retainer <NUM> is in the collapsed configuration. For example, a retainer diameter DR of retainer <NUM> and/or a retainer length LR of retainer <NUM> may be substantially similar to collapsed retainer diameter DR1 and/or retainer length LR of expandable retainer length, respectively. As with catheter <NUM>, a ratio of overlap length LOL of proximal portion <NUM> of retainer <NUM> to length LEM of expandable member <NUM> may be about <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM> or <NUM>:<NUM>, although the extent to which proximal portion <NUM> of retainer <NUM> overlaps expandable member <NUM> may vary in other examples.

Catheter <NUM> generally differs from catheter <NUM> in the configuration of the features of catheter <NUM> that enable proximal portion <NUM> of retainer <NUM> to release second end <NUM> of expandable member <NUM>. For example, elongated body <NUM> includes outer member <NUM>, to which expandable member <NUM> is mechanically connected, and inner member <NUM>, to which retainer <NUM> is mechanically connected, instead of elongated body <NUM> that may comprise a single member to which both expandable member <NUM> and expandable retainer <NUM> are attached. As discussed above, inner member <NUM> is received within lumen <NUM> defined by outer member <NUM> such that inner member <NUM> and outer member <NUM> are longitudinally movable relative to one another. Catheter <NUM> further may differ from catheter <NUM> in that proximal portion <NUM> of retainer <NUM> is configured to release second end <NUM> of expandable member <NUM> when inner member <NUM> and retainer <NUM> are moved away from expandable member <NUM> (e.g., distally) until proximal portion <NUM> of retainer <NUM> no longer overlaps second end <NUM>, instead of releasing second end <NUM> of expandable member <NUM> by expanding expandable retainer <NUM> with an inflation fluid delivered via lumen <NUM> and openings 42A, 42B.

In some other examples, first end <NUM> of expandable member <NUM> may be distal to second end <NUM> of expandable member <NUM> instead being proximal to second end <NUM>. In such other examples, first end <NUM> of expandable member <NUM> may be mechanically connected to inner member <NUM> and distal portion <NUM> of retainer <NUM> may be mechanically connected to outer member <NUM> such that distal portion <NUM> of retainer <NUM> is configured to overlap second end <NUM> of expandable member <NUM>. Thus, in such other examples, a funnel shape defined by expandable member <NUM> when expandable member <NUM> is in the expanded configuration may have a mouth facing a proximal direction (e.g., toward hub <NUM>) instead of a distal direction. In such examples, distal portion <NUM> of retainer <NUM> is configured to release second end <NUM> of expandable member <NUM> when inner member <NUM> and expandable member <NUM> are moved relative to retainer <NUM> until distal portion <NUM> no longer overlaps second end <NUM> of expandable member <NUM>. In other examples, distal portion <NUM> of retainer <NUM> may be configured to release second end <NUM> of expandable member <NUM> when outer member <NUM> and retainer <NUM> are moved relative to expandable member <NUM> until distal portion <NUM> no longer overlaps second end <NUM> of expandable member <NUM>. Thus, second end <NUM> of expandable member <NUM> generally may be released from retainer <NUM> via relative movement (e.g., longitudinal and/or rotational) of inner member <NUM> and outer member <NUM>.

Retainer <NUM> further may differ from expandable retainer <NUM> in that retainer <NUM> may not necessarily be expandable. For example, a composition of a material from which retainer <NUM> is formed may differ from a material from which retainer <NUM> is formed. Values of one more mechanical, physical, or chemical properties of the material from which retainer <NUM> is formed may thus differ from the corresponding values of one or more properties of the material from which expandable retainer <NUM> is formed. For example, a value of an elastic modulus of retainer <NUM> may be less than a value of the elastic modulus of expandable retainer <NUM>, as expandable retainer <NUM> is configured to release second end <NUM> of expandable member <NUM> by expanding from collapsed retainer diameter RD1 to expanded retainer diameter RD2.

<FIG> illustrate expandable member <NUM> of catheter <NUM> of <FIG> and an occlusive material <NUM> that catheter <NUM> optionally may include in some examples. <FIG> is a perspective view of elongated body <NUM>, expandable member <NUM>, and occlusive material <NUM>, and illustrates an example configuration of the attachment of occlusive material <NUM> to expandable member <NUM>. <FIG> is a perspective view of occlusive material <NUM> in an unfolded or expanded configuration. Occlusive material <NUM> is illustrated in <FIG> and described with respect thereto as being a structure of catheter <NUM> of <FIG> and <FIG>. However, any of the other example catheters described herein (e.g., catheter <NUM> or catheter <NUM>) may include occlusive material <NUM>, which may be attached to expandable member <NUM> or expandable member <NUM> in a manner substantially similar to that described below with respect to catheter <NUM>.

Occlusive material <NUM> may be attached to expandable retainer <NUM> and configured to expand with the expandable member <NUM> from the collapsed configuration to the expanded configuration. In other examples, occlusive material <NUM> may not necessarily be expandable, but instead may be folded into the collapsed configuration and configured to unfold into an unfolded configuration that approximates the expanded configuration of expandable member <NUM>. Occlusive material <NUM> is primarily described herein as being "expandable" from the collapsed configuration to the expanded configuration; however, it should be understood that occlusive material <NUM> may not necessarily be expandable in some such examples, but instead may be configured to unfold from the collapsed configuration when expandable retainer <NUM> is expanded.

Occlusive material <NUM> may be a flexible, substantially fluid-impermeable and/or hydrophobic material such as a polymer (e.g., ePTFE), which in some examples may be the same material from which expandable retainer <NUM> is formed. Occlusive material may be substantially fluid-impermeable such that occlusive material <NUM> does not permit a physiologically significant flow of blood therethrough. For example, occlusive material <NUM> may block <NUM>-<NUM>% of a flow of fluid through a vessel or may block any other portion of the flow of fluid through the vessel such that any remaining fluid flow not blocked by occlusive material <NUM> is not physiologically significant. Expandable member <NUM> and occlusive material <NUM> together may help prevent retrograde flow of a substance introduced into a vessel during a medical procedure (e.g., an embolic substance) past expandable member <NUM> and/or may provide a temporary vessel-occlusion device by reducing or preventing antegrade blood flow within the vessel, e.g., distal of expandable member <NUM>.

As illustrated in <FIG>, occlusive material <NUM> may be attached to expandable member <NUM> using any suitable technique. Expandable member <NUM> may define an inner surface <NUM> and an outer surface <NUM> that is radially outwards of inner surface <NUM>. In some examples, a proximal portion <NUM> (illustrated in <FIG>) of occlusive material <NUM> may be attached to inner surface <NUM> near first end <NUM> of expandable member <NUM> (e.g., at or near an apex of expandable member <NUM> when expandable member <NUM> is in the expanded configuration). Inner surface <NUM> may include inner surfaces of plurality of struts <NUM> in examples in which expandable member includes plurality of struts <NUM> or an inner surface of an expandable mesh material of expandable member <NUM>.

In some examples, occlusive material <NUM> may be attached to inner surface <NUM> via an adhesive positioned between occlusive material <NUM> and inner surface <NUM>. Additionally, or alternatively, proximal portion <NUM> of occlusive material <NUM> may be positioned between first end <NUM> of expandable member <NUM> and elongated body <NUM> such that proximal portion <NUM> of occlusive material <NUM> is attached to first end <NUM> of expandable member <NUM> when first end <NUM> of expandable member <NUM> is bonded, crimped, swaged, welded, or otherwise attached to elongated body <NUM>.

In examples in which occlusive material <NUM> is attached to inner surface <NUM> and a mouth of a funnel defined by expandable member <NUM> faces distally, occlusive material <NUM> also may be attached to inner surface <NUM> at distal portion <NUM> and/or at one or more other points on occlusive material <NUM>. Attaching occlusive material <NUM> to expandable member <NUM> at both proximal portion <NUM> and distal portion <NUM> in such examples may help prevent occlusive material <NUM> from collapsing radially inward toward central longitudinal axis <NUM> when expandable member <NUM> and occlusive material <NUM> are expanded within a vessel of a patient and antegrade blood flow exerts force on occlusive material <NUM>. To help retain occlusive material <NUM> against expandable member <NUM> in such examples, occlusive material <NUM> may be formed from or otherwise include a stiff, thin material (e.g., a biaxially oriented nylon or polyester or other similar materials), which may bias occlusive material <NUM> to self-expand against inner surface <NUM>. Additionally, or alternatively, occlusive material <NUM> may include one or more rigid ribs, which may bias occlusive material <NUM> to self-expand against inner surface <NUM>.

In some other examples, a proximal portion <NUM> (illustrated in <FIG>) of occlusive material <NUM> may be attached to outer surface <NUM> defined by expandable member <NUM>. For example, proximal portion <NUM> of occlusive material <NUM> may be attached to outer surface <NUM> near first end <NUM> of expandable member <NUM> (e.g., at or near an apex of expandable member <NUM> when expandable member is in the expanded configuration). Outer surface <NUM> may include outer surfaces of plurality of struts <NUM>, in examples in which expandable member includes plurality of struts <NUM>, or an inner surface of an expandable mesh material of expandable member <NUM>. In some examples, occlusive material <NUM> may be attached to outer surface <NUM> via an adhesive positioned between occlusive material <NUM> and outer surface <NUM>. Occlusive material <NUM> also may be attached to outer surface <NUM> at distal portion <NUM> and/or at one or more other points on occlusive material <NUM>. In any examples in which occlusive material <NUM> is attached to outer surface <NUM> and expandable member <NUM> and a mouth of a funnel defined by expandable member <NUM> faces distally, antegrade blood flow may be reduced or occluded as antegrade flow pushes occlusive material <NUM> against expandable member <NUM> when expandable member <NUM> and occlusive material <NUM> are in the expanded configurations. That is, antegrade blood flow may cause occlusive material <NUM> to seal against expandable member <NUM>, thereby reducing or occluding blood flow.

In any examples in which expandable member <NUM> and occlusive material <NUM> define a funnel having a distal-facing mouth, the orientation of expandable member <NUM> and occlusive material <NUM> may reduce or prevent antegrade-flowing blood from pooling within the funnel. Additionally, or alternatively, a distal-facing mouth of a funnel defined by expandable member <NUM> when expandable member <NUM> is in the expanded configuration may enable expandable member <NUM> to reduce retrograde flow of a substance (e.g., an embolic substance) into a parent vessel from a target vessel in which expandable member <NUM> is deployed by capturing retrograde-flowing substances within the funnel. Expandable member <NUM> and occlusive material <NUM> later may be withdrawn from the vessel and removed from the patient. For example, expandable member <NUM> may be withdrawn into an outer sheath (not shown), which then may be removed from the patient. In some examples, expandable member <NUM> may remain in the expanded configuration until expandable member <NUM> is drawn into an outer sheath, although in other examples expandable member <NUM> may be collapsed toward or into the collapsed configuration prior to withdrawal of expandable member <NUM> into an outer sheath.

As illustrated in <FIG>, proximal portion <NUM> of occlusive material <NUM> may define a proximal opening <NUM> and a distal portion <NUM> of occlusive material <NUM> may define distal opening <NUM>. Proximal opening <NUM> may be sized to receive elongated body <NUM> during a method of manufacturing catheter <NUM>. For example, proximal portion <NUM> defining proximal opening <NUM> may have an expanded diameter "DOM1," which in some examples may be substantially similar to diameter DEM3 (shown in <FIG>) of first end <NUM> of expandable member <NUM> when expandable member <NUM> is in the expanded configuration. Distal portion <NUM> defining distal opening <NUM> may have an expanded diameter DOM2, which in some examples may be substantially similar to expanded diameter DEM2(shown in <FIG>) of second end <NUM> of expandable member <NUM> when expandable member <NUM> is in the expanded configuration.

In examples in which occlusive material <NUM> is attached to outer surface <NUM> defined by expandable member <NUM>, a material from which occlusive material <NUM> is formed may be stretchable enough to be stretched over expandable member <NUM> when expandable member <NUM> is in the expanded configuration. Additionally, or alternatively, dimensions of occlusive material <NUM> may be slightly larger than corresponding dimensions of expandable member <NUM>. For example, dimensions of occlusive material <NUM> (e.g., DOM1 or DOM2) may be sufficiently larger than respective ones of diameter DEM3 and DEM2 of expandable member <NUM> to receive expandable member <NUM> while allowing occlusive material <NUM> to seal against expandable member <NUM> under the force of antegrade blood flow.

Occlusive material <NUM> further may define an outer surface <NUM>, which may define at least one opening <NUM>. In the illustrated example of <FIG>, outer surface <NUM> defines at least three openings <NUM>. Openings <NUM> may be configured to reduce air pockets that may occur in expandable member <NUM> when expandable member <NUM> is in the expanded configuration and positioned within blood flow within a vessel of a patient. In examples in which occlusive material <NUM> defines at least one opening <NUM>, occlusive material <NUM> nonetheless substantially blocks fluid flow therethrough (e.g., does not permit a physiologically significant flow of blood therethrough, as described above). Thus, even in examples in which occlusive material <NUM> defines at least one opening <NUM>, occlusive material <NUM> may be used to reduce or occlude blood flow within a vessel instead of as a filter configured to permit a greater (e.g., physiologically significant) flow of blood therethrough.

<FIG> is a flow diagram illustrating an example method of deploying and using a catheter, such as catheter <NUM>, within the vasculature of a patient as described herein. The method of <FIG> is described in conjunction with <FIG> illustrate a series of side views showing catheter <NUM> of <FIG> and <FIG> being operated in accordance with the technique described with respect to <FIG>. For example, <FIG> illustrate catheter <NUM> being advanced within a vessel <NUM>, which defines a lumen <NUM>, to a curved portion <NUM> of vessel <NUM>, as well as expandable member <NUM> being expanded into contact with an inner surface <NUM> defined by vessel <NUM> to deflect a portion of elongated body <NUM> distal to expandable member <NUM> about a deflection point <NUM>. While <FIG> are described in the context of catheter <NUM> of <FIG> and <FIG>, the technique of <FIG> may be used in conjunction with other techniques or other catheters (e.g., catheter <NUM> of <FIG> and <FIG> or catheter <NUM> of <FIG> and <FIG>).

<FIG> shows a distal portion <NUM> of catheter <NUM> positioned within vessel <NUM> of the vasculature of a patient. Distal portion <NUM> of catheter <NUM> may include at least the portion of elongated body <NUM> shown in <FIG>, expandable member <NUM>, and expandable retainer <NUM>. Prior to positioning catheter <NUM> as shown in <FIG>, a clinician may create an insertion path from an entry point accessible from outside a patient to a target site into the vasculature, e.g., with the aid of a needle or another device having a cutting surface. The clinician may introduce a guidewire into the insertion path, e.g., through the needle or another device. Once the insertion path has been created, the clinician may introduce distal portion <NUM> of catheter <NUM> into the insertion path over the guidewire, with expandable member <NUM> and expandable retainer in the respective collapsed configurations. In these examples, catheter <NUM> may function as a guide catheter, through which another catheter may be inserted, or may function as both a guide catheter and an aspiration catheter or other catheter. In some cases, the navigability of catheter <NUM> provided by expandable member <NUM> may permit catheter <NUM> to be navigated to a target treatment site in vasculature of a patient without the aid of a guide catheter. In other examples, a guide catheter or another guide device may be introduced over the guidewire and then catheter <NUM> may be inserted through a lumen of the guide device, rather than directly over the guidewire without the aid of a guide device. Hub <NUM> of catheter <NUM> (shown in <FIG> and <FIG>) may remain outside of the body of the patient.

In the example method of <FIG>, at least distal portion <NUM> of catheter <NUM> may be introduced into vessel <NUM> (<NUM>). In some examples, vessel <NUM> may be a feeding vessel that feeds a target vessel in which an interventional procedure may be performed, such as a procedure to deliver an embolic substance to treat an AVM, a procedure to treat ischemic stroke, or other vascular intervention procedure. After introduction of distal portion <NUM> of catheter <NUM> into the vasculature of the patient, the clinician then may advance distal portion <NUM> through vessel <NUM> until one or more portions of distal portion <NUM> (e.g., distal end <NUM> of elongated body <NUM>, expandable member <NUM>, and expandable retainer <NUM>) reach curved portion <NUM> of vessel <NUM> (<NUM>).

Depending one or more factors, such as a stiffness of one or more of elongated body <NUM>, expandable member <NUM>, expandable retainer <NUM>, or an angle formed by curved portion <NUM> of vessel <NUM>, distal portion <NUM> of catheter <NUM> may experience a resistive force applied by inner surface <NUM> of vessel <NUM> as distal portion <NUM> is advanced into curved portion <NUM> when distal portion <NUM> is in the substantially linear configuration illustrated in <FIG>. In some examples, the resistive force applied by inner surface <NUM> of vessel <NUM> may make in more difficult for the clinician to advance distal portion <NUM> through the portion of lumen <NUM> defined by curved portion <NUM> of vessel <NUM> without applying excessive distal pushing force to distal portion <NUM>.

In order to help advance distal portion <NUM> through the portion of lumen <NUM> defined by curved portion <NUM> of vessel <NUM> without applying excessive pushing force to distal portion <NUM>, the clinician may deploy expandable member <NUM> to cause a portion of elongated body <NUM> distal to first end <NUM> of expandable member <NUM> to deflect by bending elongated body <NUM> about deflection point <NUM>, which is proximal to first end <NUM> of expandable member <NUM>. For example, clinician may release second end <NUM> of expandable member <NUM> from expandable retainer <NUM> to allow self-expansion or balloon-aided expansion of expandable member <NUM> from the collapsed configuration shown in <FIG> to the expanded configuration shown in <FIG> and deflection of a portion of catheter <NUM> distal to deflection point <NUM> around the curved shape of curved portion <NUM> of vessel <NUM> (<NUM>). That is, a radial force applied by expandable member <NUM> to inner surface <NUM> of vessel <NUM> when expandable member <NUM> is in the expanded configuration may be sufficient to cause deflection of the portion of catheter <NUM> distal to deflection point <NUM>. However, the radial force applied by expandable member <NUM> to inner surface <NUM> may not necessarily be sufficient to fix catheter <NUM> in place within vessel <NUM>.

In the example of catheter <NUM>, the clinician may release second end <NUM> of expandable member <NUM> from expandable retainer <NUM> by introducing a fluid into expandable retainer <NUM> to expand expandable retainer <NUM>. For example, the clinician may introduce the fluid into lumen <NUM> defined by elongated body <NUM> via first port <NUM> and/or second port <NUM> of hub <NUM>. The fluid introduced into lumen <NUM> may exit lumen <NUM>, via openings 42A, 42B defined by outer wall <NUM> defined by elongated body <NUM>. As illustrated in <FIG>, expandable retainer <NUM> further may define an inner surface <NUM>. Force exerted by the fluid on inner surface <NUM> of expandable retainer <NUM> may cause expandable retainer <NUM> to expand to the expanded configuration, thereby releasing second end <NUM> of expandable member <NUM> while first end <NUM> remains mechanically coupled to elongated body <NUM>. In examples in which expandable member <NUM> is self-expanding, expandable member <NUM> may expand radially outward in response to its second end <NUM> being released from expandable retainer <NUM>.

In examples in which the technique of <FIG> is used in conjunction with catheter <NUM> of <FIG> and <FIG>, the clinician instead may release second end <NUM> of expandable member <NUM> from retainer <NUM> by moving inner member <NUM> relative to outer member <NUM>, either by moving inner member <NUM>, outer member <NUM>, or both inner and outer members <NUM>, <NUM>, thereby distally moving retainer <NUM> and causing retainer <NUM> to release second end <NUM> of expandable member <NUM>. In examples in which expandable member <NUM> is self-expanding, after retainer <NUM> releases second end <NUM> of expandable member <NUM>, expandable member <NUM> expands radially outward from the collapsed configuration illustrated in <FIG> to the expanded configuration illustrated in <FIG> while first end <NUM> remains mechanically coupled to elongated body <NUM>.

As expandable member <NUM> expands from the collapsed configuration shown in <FIG> to the expanded configuration shown in <FIG>, a portion of expandable member <NUM> contacts inner surface <NUM> defined by vessel <NUM> and helps to better conform elongated body <NUM> to the curved shape of curved portion <NUM>. In some examples, expandable member <NUM> may be self-expandable. In other examples, expandable member <NUM> may be expandable via actuation of a push/pull wire attached to expandable member <NUM> (not shown), or any other suitable feature configured to expand and/or collapse expandable member <NUM>. In examples in which expandable member <NUM> defines a funnel, such as the example illustrated in <FIG>, at least second end <NUM> of expandable member <NUM> may contact inner surface <NUM>. In any such examples, resistive force applied by inner surface <NUM> to expandable member <NUM> when expandable member <NUM> is in substantial conformation with inner surface <NUM> may be translated to elongated body <NUM> via expandable member <NUM>, causing deflection of a portion of elongated body <NUM> distal to expandable member <NUM> about deflection point <NUM>.

With the portion of elongated body <NUM> distal to expandable member <NUM> deflected about deflection point <NUM>, distal end <NUM> of elongated body <NUM> may be reoriented away from inner surface <NUM> such longitudinal axis defined by catheter <NUM> and elongated body <NUM> (e.g., longitudinal axis <NUM>, shown in <FIG>) is substantially parallel to a longitudinal axis defined by vessel <NUM> (not shown). Re-orienting distal end <NUM> of elongated body <NUM> in this manner may alleviate resistance applied to distal end <NUM> by inner surface <NUM>, thereby reducing the amount of distal pushing force needed to continue advancing distal portion <NUM> of catheter <NUM>. Additionally, or alternatively, the clinician may deploy expandable member <NUM> to steer distal end <NUM> of elongated body into a desired one of multiple vessels that branch off from vessel <NUM>. In this manner, expandable member <NUM> may enable steering of distal portion <NUM> of catheter <NUM> through tortuous regions of the vasculature of the patient along a desired path of travel to a treatment site within a target vessel, which may help increase the efficiency and/or improve a clinical outcome of the procedure.

The clinician then may continue to advance distal portion <NUM> of catheter <NUM> through vessel <NUM> to a treatment site within a target vessel, which may be vessel <NUM> or another vessel within the vasculature of the patient (<NUM>). In some examples, expandable member <NUM> may be collapsed back toward, or into, the collapsed configuration before the clinician continues to advance distal portion <NUM>. For example, as previously mentioned, catheter <NUM> may include a push/pull wire attached to expandable member <NUM> (not shown) that may be actuated to expand and/or collapse expandable member <NUM>, or any other suitable feature that may be configured to expand and/or collapse expandable member <NUM>. Additionally, or alternatively, expandable retainer <NUM> may be collapsed back toward, or into, the collapsed configuration before the clinician continues to advance distal portion <NUM> through vessel <NUM> toward the treatment site, such as by aspirating fluid used to expand expandable retainer <NUM> from expandable retainer <NUM>.

In some other examples, catheter <NUM> may be a guide catheter defining a lumen through which an interventional catheter (e.g., a catheter configured for aspiration and/or delivery of an interventional device such as a thrombectomy device or stent retriever, and/or a drug or medical agent) may be delivered. In such examples, instead of advancing distal portion <NUM> of catheter <NUM> through vessel <NUM> to the treatment site, the clinician instead may leave distal portion <NUM> of catheter <NUM> in place within vessel <NUM>, as illustrated in <FIG>, and introduce the interventional catheter through catheter <NUM> to the treatment site.

In examples in which the clinician has advanced distal portion <NUM> to the treatment site with expandable member <NUM> in the collapsed configuration, the clinician may expand expandable member <NUM> prior to conducting the interventional procedure. With expandable member <NUM> in the expanded configuration at the treatment site, expandable member <NUM> may be in contact with inner surface <NUM> of vessel <NUM>, thereby reducing or occluding blood flow within vessel <NUM>. For example, radial force applied by expandable member <NUM> to inner surface <NUM> of vessel <NUM> when expandable member <NUM> is in the expanded configuration may be sufficient to reduce or occlude blood flow within vessel <NUM>. However, the radial force applied by expandable member <NUM> to inner surface <NUM> when expandable member <NUM> is at the treatment site may not necessarily be sufficient to fix catheter <NUM> in place within vessel <NUM>. With distal portion <NUM> of catheter <NUM> positioned at the treatment site within the target vessel, the clinician then may conduct an interventional procedure, such as a procedure to introduce an embolic substance for treatment of an AVM, ischemic stroke, or other condition via thrombectomy, embolectomy, aspiration, aneurysm treatment procedure, stent placement, or any other suitable procedure (<NUM>). The clinician then may withdraw distal portion <NUM> of catheter <NUM> from vessel <NUM> and remove distal portion <NUM> from the patient (e.g., following the interventional procedure). For example, the clinician may withdraw distal portion <NUM> into an outer sheath or another catheter (not shown), which then may be removed from the patient. In some examples, expandable member <NUM> may remain in the expanded configuration until expandable member is drawn into the outer sheath or other catheter. In other examples, the clinician may collapse expandable member <NUM> toward or into the collapsed configuration prior to withdrawing expandable member <NUM> (e.g., by actuating a push/pull wire attached to expandable member <NUM>) into the outer sheath or other catheter.

<FIG> is a flow diagram illustrating another example method of deploying and using a catheter, such as catheter <NUM>, within the vasculature of a patient as described herein. While <FIG> is described in the context of catheter <NUM> of <FIG> and <FIG>, the techniques of <FIG> may be used in conjunction with other techniques or other catheters (e.g., catheter <NUM> of <FIG> and <FIG> or catheter <NUM> of <FIG> and <FIG>). As with the flow diagram of <FIG>, the flow diagram of <FIG> is described in conjunction with <FIG>. While <FIG> is described with reference to catheter <NUM> of <FIG> and <FIG>, the technique of <FIG> may be used in conjunction with other techniques or other catheters (e.g., catheter <NUM> of <FIG> and <FIG> or catheter <NUM> of <FIG> and <FIG>).

One or more steps of the example method of <FIG> may be substantially similar to the corresponding steps of example method of <FIG> and will not be discussed again in detail here. For example, in the method of <FIG>, a clinician may introduce at least distal portion <NUM> of catheter <NUM> introduced into vessel <NUM> (<NUM>) in a manner substantially as described with respect to (<NUM>) of <FIG>. The clinician may advance distal portion <NUM> of catheter <NUM> through vessel <NUM> to a treatment site within a target vessel, which may be vessel <NUM> or another vessel within the vasculature of the patient.

(<NUM>), in a manner substantially as described with respect to (<NUM>) of <FIG>. For example, the clinician may release second end <NUM> of expandable member <NUM> from expandable retainer <NUM> by introducing a fluid into expandable retainer <NUM> to expand expandable retainer <NUM>, or, in the example of catheter <NUM>, by moving inner member <NUM> and retainer <NUM> distally until proximal portion <NUM> of retainer <NUM> no longer overlaps second end <NUM> of expandable member <NUM> (<NUM>) in a manner substantially as described with respect to (<NUM>) of <FIG> and such that expandable member engages with a vessel wall at or near the treatment site. With distal portion <NUM> of catheter <NUM> positioned at the treatment site within the target vessel, the clinician then may conduct an interventional procedure, such as a procedure to introduce an embolic substance for treatment of an AVM, ischemic stroke, or other condition via embolectomy, aneurysm treatment procedure, stent placement, or any other suitable procedure (<NUM>) in a manner substantially as described with respect to (<NUM>) of <FIG>.

The example method of <FIG> may differ from the example of <FIG> in that the clinician may release second end <NUM> of expandable member <NUM> from expandable retainer <NUM> to expand expandable retainer <NUM> (<NUM>) after advancing distal portion <NUM> of catheter <NUM> to the treatment site (<NUM>) instead of before distal portion <NUM> of catheter <NUM> reaches the treatment site. For example, if a vessel is through which distal portion <NUM> of catheter <NUM> is advanced is substantially linear between the entry point and the treatment site, the clinician may not necessarily deploy expandable member <NUM> to help steer distal portion <NUM> of catheter <NUM>. Thus, in such examples, the clinician may expand expandable retainer <NUM> to release second end <NUM> of expandable member <NUM> from expandable retainer <NUM> when distal portion <NUM> of catheter <NUM> is at the treatment site.

In the example method of <FIG>, catheter <NUM> may include occlusive material <NUM> attached to expandable member <NUM>, as described with respect to <FIG>. Expandable member <NUM> and occlusive material <NUM> together may help prevent retrograde flow of a substance introduced into a vessel during a medical procedure (e.g., an embolic substance) past expandable member <NUM> without requiring the clinician to perform a timeconsuming step of casting a plug of embolic substance at a tip of a delivery catheter used to deliver the embolic substance. Additionally, or alternatively, expandable member <NUM> and occlusive material <NUM> may provide a temporary vessel-occlusion device by reducing or preventing antegrade blood flow within the vessel. In any such examples, expandable member <NUM> and occlusive material <NUM> may reduce or eliminate a need for the use of a balloon backstop to reduce or prevent antegrade blood flow and/or retrograde flow of a substance introduced into the vessel during a vascular treatment procedure.

The example methods of <FIG> and <FIG> are intended to be exemplary in nature. Thus, the example methods of <FIG> and <FIG> are not limited to the steps described above and are not intended to be mutually exclusive. For example, an example method of deploying and using a catheter (e.g., catheter <NUM>) within the vasculature of a patient may include releasing second end <NUM> of expandable member <NUM> from expandable retainer <NUM> to allow expansion of expandable member <NUM> and deflection of a portion of catheter <NUM> distal to deflection point <NUM> around a curved shape of curved portion <NUM> of vessel <NUM> (<NUM>) and collapsing expandable member <NUM> back toward or into the collapsed configuration after the clinician has advanced distal portion <NUM> of catheter <NUM> past curved portion of vessel <NUM>. In such examples, expandable member <NUM> may be in a substantially collapsed configuration when the clinician advances distal portion <NUM> of catheter <NUM> to the treatment site but no longer retained at second end <NUM> by expandable retainer <NUM>. In such examples, the clinician may re-expand expandable member <NUM> at the treatment site (e.g., by actuating a push/pull wire attached to expandable member <NUM>) without necessarily expanding expandable retainer <NUM>.

Claim 1:
A catheter (<NUM>,<NUM>) comprising:
an elongated body (<NUM>,<NUM>);
an expandable member (<NUM>,<NUM>) extending from a first end (<NUM>,<NUM>) to a second end (<NUM>,<NUM>), the first end (<NUM>,<NUM>) of the expandable member (<NUM>,<NUM>) being mechanically connected to the elongated body (<NUM>,<NUM>), wherein the expandable member (<NUM>) is configured to expand radially outward away from the elongated body (<NUM>,<NUM>) from a collapsed configuration to an expanded configuration; and
an expandable retainer (<NUM>,<NUM>) configured to overlap the second end of the expandable member (<NUM>,<NUM>) to hold the expandable member (<NUM>,<NUM>) in the collapsed configuration, wherein the expandable retainer (<NUM>,<NUM>,<NUM>) is configured as a balloon, and wherein the expandable retainer (<NUM>,<NUM>,<NUM>) is expandable to release the second end (<NUM>,<NUM>,<NUM>) of the expandable member (<NUM>,<NUM>,<NUM>) to enable the expandable member (<NUM>,<NUM>,<NUM>) to expand from the collapsed configuration to the expanded configuration.