Patent Description:
A medical catheter defining at least one lumen has been proposed for use with various medical procedures. For example, in some cases, a medical catheter may be used to access and treat defects in blood vessels, such as, but not limited to, lesions or occlusions in blood vessels. <CIT> discloses a catheter including an elongated body including a proximal portion and a distal portion. The elongated body includes an inner liner, an outer jacket, a structural support member positioned between at least a portion of the inner liner and at least a portion of the outer jacket, and an expandable member coupled to the structural support member at the distal portion of the elongated body. The expandable member may be configured to expand radially outward, e.g., to engage a clot within vasculature of a patient.

<CIT> discloses a reentry device for withdrawing an object into a distal end of a sheath. <CIT> discloses methods and catheter apparatus for passing one or more guidewires (via the use of one or more telescoping guidewire lumens) through a chronic total occlusion of a vasculature. <CIT> discloses a radiopaque composite wire for medical applications has a core comprising a rare earth metal, an outer layer comprising a nickel-titanium alloy disposed over the core, and a controlled diffusion zone between the core and the outer layer.

This disclosure describes example catheters including an elongated body and an expandable member at a distal portion of the elongated body and defining at least part of a distal tip of the catheter. The expandable member is configured to expand radially outward within a hollow anatomical structure (e.g., a blood vessel) of a patient, e.g., to engage a thrombus. The expandable member is formed from materials that enable a distal tip of the catheter to be radiopaque without the addition of a separate radiopaque marker (e.g., a solid metal ring of radiopaque material separate from and connected to the elongated body) at the distal tip of the catheter, e.g., proximal to the expandable member. A solid metal radiopaque marker band may contribute to the overall stiffness of a distal tip of a catheter. Forming the expandable member from a radiopaque material may enable the solid metal radiopaque marker to be eliminated from the distal tip of the catheter, thereby enabling the distal tip of the catheter to be more flexible. In addition, because the expandable member is formed from a radiopaque material, a longer extent of the distal tip of the catheter may be visible under fluoroscopy or x-ray imaging. This may provide a clinician with a better indication of a location of the distal tip within a patient.

In some examples, the expandable member is formed from a plurality of structural elements (e.g., drawn-filled tubes), each structural element comprising an outer first material surrounding an inner core comprising a second material, where the first material is more radiopaque than the second material, or where the second material is more radiopaque than the first material. For example, the expandable member may include a braided structure comprising interwoven structural elements. As another example, the expandable member may include a stent-like expandable frame defined by struts, each strut being formed from a structural element. In other examples, the expandable member includes a braided structure comprising first filaments of a first material interwoven with second filaments of a second material, wherein the second material is more radiopaque than the first material.

In some examples in which an expandable member of a catheter is formed from a radiopaque material, the catheter is devoid of any separate radiopaque markers at a distal tip of the elongated body, e.g., anywhere along the expandable member. For example, a radiopaque marker band may be located at a more-proximal portion of the catheter, such as proximal to the expandable member, but not distal to a proximal end of the expandable member. In other examples, the catheter is devoid of any solid metal radiopaque marker bands anywhere along the catheter.

This disclosure also describes examples of methods of forming the catheters described herein and methods of using the catheters.

According to the invention, there is provided, a catheter according to claim <NUM>. Optional features are defined in the dependent claims.

In some examples, the catheter includes a radiopaque marker band located at a junction between the elongated body and the expandable member.

In some examples, an outer diameter of the expandable member while the expandable member is in an expanded configuration is greater than an outer diameter of the elongated body.

In some examples of the catheter, the expandable member defines a cylindrical tube when in an expanded configuration.

In some examples, a distal end of the cylindrical tube forms a distal mouth of the catheter when the expandable member is in the expanded configuration.

In some examples, when the expandable member is in the expanded configuration, an outer diameter of the cylindrical tube is greater than an outer diameter of the distal body portion, wherein the outer diameter of the cylindrical tube is no more than <NUM>% of the outer diameter of the distal body portion.

In some examples, the cylindrical tube has an axial length of about <NUM> centimeters to about <NUM> centimeters while the expandable member is in the expanded configuration.

In some examples, the expandable member includes a tapered section at a proximal end of the cylindrical tube when the expandable member is in the expanded configuration.

In some examples, the expandable member further includes a proximal section at a proximal end of the tapered section, wherein an outer diameter of the proximal section is substantially equal to an outer diameter of the distal body portion of the elongated body.

In some examples of the catheter, the cylindrical tube defines a distal-most section of the expandable member.

In some examples of the catheter, the first material includes an electroplated coating on an exterior surface of the core.

In some examples of the catheter, one or more structural elements of the plurality of structural elements includes a drawn-filled tube.

In some examples of the catheter, the plurality of structural elements include filaments interwoven into a braided structure.

In some examples of the catheter, the plurality of structural elements include struts defining an expandable frame.

In some examples, the elongated body further includes: an inner liner; a structural support member; and an outer jacket, wherein the structural support member is positioned between the inner liner and the outer jacket.

In some examples, the structural support member includes a coil and a braid disposed over at least a portion of the coil.

In some examples, the expandable member extends over at least a portion of the coil.

In some examples, the structural support member includes a coil, and the expandable member extends over at least a portion of the coil.

In some examples, the inner liner extends distally past a proximal end of the expandable member.

In some examples, the distal body portion includes a plurality of concentric layers, and a proximal end of the plurality of structural elements of the expandable member forms one of the concentric layers along an axial length of the distal body portion.

In some examples, the concentric layers of the distal body portion include a structural support member having a distal end, and a proximal end of the plurality of structural elements of the expandable member is located distal of the distal end of the structural support member.

In some examples, the proximal end of the plurality of structural elements and the structural support member are substantially radially equidistant from a central longitudinal axis of the catheter.

In some examples of the catheter, the catheter does not have a solid metal radiopaque marker band distal to a proximal end of the expandable member.

In some examples, the first material includes a nickel-titanium alloy, and wherein the second material includes platinum or a platinum alloy.

In some examples, the first material includes gold, and the second material includes a nickel-titanium alloy.

In some examples, the expandable member further includes a flexible membrane coupled to the plurality of structural elements.

In some examples, the flexible membrane at least partially covers an inner surface or an outer surface of the plurality of structural elements.

In some examples, the flexible membrane includes a fluid-impermeable polymer.

In some examples, the flexible membrane is radiopaque.

In some examplesthe flexible membrane includes a thermoplastic elastomer combined with a radiopaque material.

In some examples, the expandable member is configured to axially contract in response to an application of a suction force to the proximal body portion of the elongated body.

In some examples, the expandable member has an axial length of about <NUM> centimeters to about <NUM> centimeters.

In some examples, when the expandable member is in an expanded configuration, a greatest outer diameter of the expandable member is greater than an outer diameter of the distal body portion, and the outer diameter of the cylindrical tube is no more than <NUM>% of the outer diameter of the distal body portion.

In some examples, while a suction force is applied to the body inner lumen, the expandable member is configured to axially contract in response to contact with a thrombus enabling a user to observe, via fluoroscopic imagery, that the catheter is engaged with the thrombus.

In some examples, a system includes an introducer sheath; the catheter of the invention; and a compression tool configured to compress the expandable member for insertion of the catheter into the introducer sheath.

The examples described herein may be combined in any permutation or combination.

The disclosure describes a medical device, referred to herein as a "catheter," including an expandable member configured to expand radially outward within a hollow anatomical structure (e.g., a blood vessel) of a patient, e.g., to engage with a thrombus to facilitate aspiration of the thrombus (or other material or object(s) to be removed, such as a plaque or foreign body). Some catheters include a distinct radiopaque marker band (e.g., a solid metal ring) near a distal tip of the catheter, which may facilitate placement of the catheter via fluoroscopic imaging. This radiopaque marker band may also contribute to an overall (e.g., excessive) stiffness of the distal tip of the catheter, which may adversely impact navigability of the catheter to distal sites in the vasculature of a patient. According to the examples of this disclosure, the expandable members described herein can be integrally formed from one or more materials that enable a distal tip or portion of the catheter to be radiopaque without the addition of a separate, more-rigid radiopaque marker band (e.g., a solid metal radiopaque marker band), thereby improving the flexibility of the distal tip and improving the navigability of the catheter. In addition, because a length of the expandable member is formed from a radiopaque material as compared to a separate, smaller or shorter (as measured in a direction parallel to a longitudinal axis of the catheter) radiopaque marker band, a longer portion of the distal tip or distal portion of the catheter (e.g., about <NUM> centimeter to about <NUM> centimeters) may be visible under fluoroscopy or x-ray imaging, thereby providing a clinician with a better indication of a location of the distal tip or distal portion within the vasculature of the patient.

Example catheters in accordance with this disclosure include a relatively flexible elongated body configured to be navigated through vasculature of a patient, e.g., tortuous vasculature in a brain of the patient. The elongated body may include a plurality of concentric layers, such as an inner liner, an outer jacket, and a structural support member (e.g., a coil, braid, and/or hypotube) positioned between at least a portion of the inner liner and outer jacket. A distal tip or distal portion of the catheter includes an expandable member, such as an expandable stent-like structure or an expandable braid, positioned distal to a distal portion of the elongated body. In some examples, the expandable member is distinct from, but mechanically coupled to, the distal portion of the elongated body. In other examples, the expandable member is integrally formed with (e.g., laminated with and/or forming a distal extension of) the distal portion of the elongated body. The expandable member is configured to expand radially outward within a hollow anatomical structure (e.g., a blood vessel) of the patient. This may enable, for example, the expandable member to engage with a thrombus, such as a clot, embolism, or other material such as plaques or foreign bodies during an aspiration procedure, such as, but not limited to, a medical procedure using A Direct Aspiration first Pass Technique (ADAPT) for acute stroke thrombectomy.

The expandable member may help improve aspiration of the thrombus into the catheter by providing a relatively large luminal diameter (and therefore exert a larger aspiration force against the thrombus or other material to be removed) and interior space for the thrombus to engage with the catheter compared to examples in which an otherwise similar catheter does not include an expandable member. For example, such a catheter that does not include an expandable member may have limited radial expansion due to a structural support member that extends to the distal end of the catheter, and may thus make it harder to aspirate a thrombus (e.g., due to a smaller cross-sectional dimension of the distal end of the catheter). The expandable member may overcome such radial expansion limitations, thereby increasing thrombus engagement, reducing the amount of time required for revascularization, and increasing revascularization success rates for various procedures, as compared to similar procedures performed using catheters that do not include an expandable member to engage a thrombus.

In some examples, the radiopacity of the expandable member is provided by a plurality of structural elements from which the expandable element is formed, some or all of the structural elements comprising an outer first material surrounding an inner core comprising a second material, where the first material is more radiopaque than the second material, or wherein the second material is more radiopaque than the first material. For example, some or all of the structural elements can comprise a wire or filament, which can take the form of a drawn-filled tube. In some examples, the expandable member includes a braided structure comprising braided or interwoven filaments, some or all of the filaments being formed from such a structural element. In other examples, the expandable member may include a stent-like expandable frame defined by struts, each strut being formed from a structural element.

In other examples, in addition to, or instead of, the aforementioned structural elements, the radiopacity of the expandable member is provided by radiopaque structural elements combined with less radiopaque or even radiotransparent structural elements. For example, the expandable element can include a braided structure comprising first filaments of a first material interwoven with second filaments of a second material, where either the first material or the second material is more radiopaque than the other (e.g., where one of the two materials is radiopaque and the other is not radiopaque, or where both materials are radiopaque but one is more radiopaque than the other). In other examples, the expandable element includes a multicoaxial-layered laser-cut stent, wherein at least one of the coaxial layers includes a material that is radiopaque.

<FIG> is a conceptual side view of an example catheter <NUM>, and <FIG> is a conceptual cross-sectional view of a distal tip or distal portion <NUM> of the example catheter <NUM>. As shown in <FIG> and <FIG>, catheter <NUM> can include an elongated body <NUM>, a hub <NUM>, and an expandable member <NUM>. Catheter <NUM> defines an inner lumen <NUM>, including a hub lumen 26A, a body lumen 26B, and an expandable member lumen 26C.

Elongated body <NUM> is configured to be advanced through vasculature of a patient via a pushing force applied to proximal body portion 16A (e.g., via hub <NUM>) of elongated body <NUM> without buckling, kinking, or otherwise undesirably deforming (e.g., ovalization). As shown in <FIG>, elongated body <NUM> can include a plurality of concentric layers, such as an inner liner <NUM>, an outer jacket <NUM>, and a structural support member <NUM> positioned between at least a portion of inner liner <NUM> and at least a portion of outer jacket <NUM>. Elongated body <NUM> includes a proximal body portion 16A and a distal body portion 16B, which are each longitudinal sections of elongated body <NUM> and do not overlap in the longitudinal direction (along longitudinal axis <NUM>). Elongated body <NUM> extends from body proximal end 12A to body distal end 12B and defines at least one body lumen 26B (also referred to as a body inner lumen). In the example shown in <FIG>, proximal end 12A of elongated body <NUM> is received within hub <NUM> and is mechanically connected to hub <NUM> via an adhesive, welding, or another suitable technique or combination of techniques. Inner lumen <NUM> of catheter <NUM> may be defined by portions of hub <NUM>, inner liner <NUM>, and expandable member <NUM>.

Catheter <NUM> may be used as an aspiration catheter to remove a thrombus or other material such as plaques or foreign bodies from vasculature of a patient. In such examples, a suction force (e.g., a vacuum) may be applied to proximal end 10A of catheter <NUM> (e.g., via hub <NUM>) to draw a thrombus or other blockage into inner lumen <NUM>. An aspiration catheter may be used in various medical procedures, such as a medical procedure to treat an ischemic insult, which may occur due to occlusion of a blood vessel (arterial or venous) that deprives brain tissue, heart tissue or other tissues of oxygen-carrying blood.

In some examples, catheter <NUM> is configured to access relatively distal locations in a patient including, for example, the middle cerebral artery (MCA), internal carotid artery (ICA), the Circle of Willis, and tissue sites more distal than the MCA, ICA, and the Circle of Willis. The MCA, as well as other vasculature in the brain or other relatively distal tissue sites (e.g., relative to the vascular access point), may be relatively difficult to reach with a catheter, due at least in part to the tortuous pathway (e.g., comprising relatively sharp twists or turns) through the vasculature to reach these tissue sites. Elongated body <NUM> may be structurally configured to be relatively flexible, pushable, and relatively kink- and buckle- resistant, so that it may resist buckling when a pushing force is applied to a relatively proximal section of catheter <NUM> (e.g., via hub <NUM>) to advance elongated body <NUM> distally through vasculature, and so that it may resist kinking when traversing around a tight turn in the vasculature. In some examples, elongated body <NUM> is configured to substantially conform to the curvature of the vasculature. In addition, in some examples, elongated body <NUM> has a column strength and flexibility that allow at least distal body portion 16B of elongated body <NUM> to be navigated from a femoral artery, through the aorta of the patient, and into the intracranial vascular system of the patient, e.g., to reach a relatively distal treatment site.

Although primarily described as being used to reach relatively distal vasculature sites, catheter <NUM> may also be configured to be used with other target tissue sites. For example, catheter <NUM> may be used to access tissue sites throughout the coronary and peripheral vasculature, the gastrointestinal tract, the urethra, ureters, fallopian tubes, veins and other hollow anatomical structures of a patient.

In some examples, a "working length" of catheter <NUM> may be measured from distal end 14B of hub <NUM> (e.g., a distal end of a strain relief member of a hub assembly) to distal end 10B of catheter <NUM> along longitudinal axis <NUM>. The working length of catheter <NUM> may depend on the location of the target tissue site within the body of a patient or may depend on the medical procedure for which catheter <NUM> is used. For example, if catheter <NUM> is a distal access catheter used to access vasculature in a brain of a patient from a femoral artery access point at the groin of the patient, catheter <NUM> may have a working length of about <NUM> centimeters (cm) to about <NUM> or more, such as about <NUM>, although other lengths may be used. The distal tip or distal portion <NUM> of catheter <NUM>, including distal body portion 16B of elongated body <NUM> and expandable member <NUM>, may be about <NUM> to about <NUM> in length. Proximal body portion 16A of elongated body <NUM> may be about <NUM> to about <NUM> in length, depending on the length of distal tip or distal portion <NUM>.

Expandable member <NUM> is configured to radially expand within a vessel of a patient, e.g., to engage a thrombus within the vessel. Expandable member <NUM> is positioned at (e.g., overlapping with or entirely distal to) distal body portion 16B of elongated body <NUM>, such that a distal end of expandable member <NUM> defines distal end 10B of catheter <NUM> and a distal mouth <NUM> open to inner lumen <NUM> of catheter <NUM>. For example, expandable member lumen 26C (also referred to as an expandable member inner lumen) forms a distal extension of the inner lumen 26B of the elongated body <NUM>. In these examples, expandable member lumen 26C is in fluid communication with inner lumen 26B of the elongated body <NUM>.

Expandable member <NUM> can include a frame configured to expand radially outward, thereby expanding lumen 26C radially outward. The frame of expandable member <NUM> can be formed from at least two different materials (e.g., two different chemical compositions), one of which is more radiopaque than the other, which can be less radiopaque or radiotransparent. For example, the expandable frame can enable expandable member <NUM> to maintains its expanded shape (after it is expanded), even in the presence of a suction force applied to inner lumen <NUM> of catheter <NUM> during an aspiration process. Example expandable frames include an expandable stent-like structure or an expandable tubular braid or weave, which can each be formed from a plurality of structural elements, each structural element comprising a first material surrounding a core comprising a second material, where the first material is more radiopaque than the second material, or wherein the second material is more radiopaque than the first material. For example, each structural element can comprise a wire or filament, which can take the form of a drawn-filled tube. In some examples, the expandable member includes a braided structure comprising interwoven filaments, each filament being formed from such a structural element.

In other examples, the expandable frame of expandable member <NUM> may be formed from radiopaque structural elements combined with less radiopaque or even radiotransparent structural elements.

In any of these examples, expandable member <NUM> may include a flexible membrane <NUM> coupled to (e.g., radially inward and/or radially outward of) the expandable frame, or integrated into the expandable frame. In some examples, flexible membrane <NUM> may be formed of an elastomeric material, such as polyolefin thermoplastic elastomers, polyurethane elastomeric alloys or silicone, that permits the expansion of expandable member <NUM>. In other examples, expandable member <NUM> does not include such flexible membrane <NUM>.

Instead of or in addition to including a relatively small (e.g., relatively short or narrow, as measured in an axial direction, along longitudinal axis <NUM>) radiopaque marker band, such as a solid metal radiopaque ring or partial ring, located at a distal portion or tip of the catheter, in examples described herein, a radiopaque material extends across or throughout a substantial portion of a longitudinal length of expandable member <NUM> (e.g., along a length parallel to longitudinal axis <NUM>). Such configurations enable a solid metal radiopaque marker band to be eliminated from the distal tip of catheter <NUM> while still enabling the distal tip of catheter <NUM> to be radiopaque, which may provide one or more advantages over a catheter including a solid radiopaque marker band at the distal tip. For example, a solid metal radiopaque marker band may be formed from a relatively rigid ring of metal (e.g., platinum-iridium), and may contribute to the overall stiffness of a distal tip or portion of a catheter. Forming expandable member <NUM> from a solid metal radiopaque material may enable such a stiff radiopaque marker band to be eliminated from the distal tip or portion of catheter <NUM>, thereby enabling the distal tip or portion <NUM> of catheter <NUM> to be more flexible. In addition, by eliminating the rigid radiopaque marker band, a distal tip or portion <NUM> of catheter <NUM> may be less rigid and more easily expand or neck down for delivery into vasculature of a patient through a sheath. This increased radial flexibility (e.g., range of expandability in a radial direction) may be useful, for example, when a relatively smaller introducer catheter is required for insertion via certain vasculature access sites, such as the radial artery. As one non-limiting example, a radial access sheath may have an inner diameter of about <NUM> French, as compared to about <NUM> French for femoral access sheaths. Accordingly, a smaller diameter (or other maximum cross-sectional dimension) catheter <NUM> may be useful for such applications.

Incorporating the radiopaque material throughout the axial length of expandable member <NUM> enables a longer extent of the distal tip or portion <NUM> of catheter <NUM> (e.g., about <NUM> centimeters to about <NUM> centimeters, such as about <NUM> centimeters to about <NUM> centimeters) to be visible under fluoroscopy or x-ray imaging. This may provide a clinician with a better indication of a location of the distal tip or portion <NUM> within a patient. In addition, expandable member <NUM> formed from a radiopaque material may be fluoroscopically illuminated, enabling the clinician to monitor the shape of expandable member <NUM> as the clinician navigates expandable member <NUM> through the patient's vasculature. For example, the radiopaque material may enable the clinician to observe when expandable member <NUM> is bending or not bending around a curve in the patient's vasculature. As another example, the radiopaque material may allow the clinician to observe if expandable member <NUM> becomes kinked or otherwise deformed in an undesirable manner that may inhibit navigation of catheter <NUM> through the vasculature. A radiopaque marker band alone, on the other hand, would not enable a shape of expandable member <NUM> to be visible under fluoroscopy or x-ray imaging.

In addition, by incorporating a radiopaque material throughout expandable member <NUM>, a clinician may be able to more-easily discern when the distal mouth <NUM> of expandable member <NUM> has come into contact with a thrombus within the vasculature of a patient. For example, the clinician may distally advance expandable member <NUM> through the vasculature of the patient toward a thrombus. When the mouth <NUM> of expandable member <NUM> contacts the thrombus, the thrombus may form a seal over the distal mouth <NUM> of expandable member <NUM>. In the presence of a suction force (e.g., via an aspiration pump) applied to inner lumen <NUM> of catheter <NUM>, such a seal over the mouth <NUM> of expandable member <NUM> may cause expandable member <NUM> to partially axially contract and/or otherwise change shape along longitudinal axis <NUM>. Expandable member <NUM> may be configured to partially axially contract and/or otherwise change shape when engaged with a thrombus due to its relative flexibility, e.g., compared to expandable members that include a solid metal radiopaque marker band. Due to the radiopaque material of expandable member <NUM>, the clinician may easily observe this axial contraction of expandable member <NUM> on a fluoroscopic imaging screen, informing the clinician when catheter <NUM> has engaged the thrombus.

In some, but not all, examples, catheter <NUM> includes a more rigid radiopaque marker band (e.g., a solid metal radiopaque ring or partial ring) proximal to expandable member <NUM> along elongated body <NUM>. For example, as shown in <FIG>, catheter <NUM> may include a marker band <NUM> located at the distal end of elongated body <NUM>, e.g., at the junction between elongated body <NUM> and expandable member <NUM>. Marker band <NUM> can be entirely proximal to a proximal end of expandable member <NUM> in some examples. Marker band <NUM> may improve the durability of the joint between the elongated body <NUM> and expandable member <NUM>, and may also act as a locator point to help a clinician identify the proximal end of expandable member <NUM> within fluoroscopic imagery. For example, expandable member <NUM> alone, though radiopaque, may be relatively less radiopaque than marker band <NUM>. Accordingly, marker band <NUM> may help a clinician to more quickly locate expandable member <NUM> within the fluoroscopic imagery.

In some examples, in its expanded states, expandable member <NUM> defines a tubular, cylindrical, or funnel shape configured to provide catheter <NUM> with a relatively large diameter (or other maximum cross-sectional diameter) distal end 10B (compared to, for example, proximal body portion 16A of elongated body <NUM>) and interior space 26C for better engagement with a thrombus (e.g., clot or embolus). In some examples, the cross-section of expandable member <NUM> in its expanded state may be round (e.g., circular) and the cross-sectional axis may be referred to as a diameter. In some examples, the cross-section may be irregularly shaped, in which case the cross-sectional dimension may be referred to as the major axis (e.g., a longest dimension of the cross-section). In the expanded configuration, the cross-section of expandable member <NUM> may be wider at a distal end than a proximal end. For example, in the expanded configuration, the inner diameter at the distal end of expandable member <NUM> (e.g., along all or part of distal section 20C of expandable member (<FIG>) and/or at distal opening <NUM>) may be about <NUM> percent to about <NUM> percent wider than an inner diameter of expandable member <NUM> near distal body portion 16B of elongated body <NUM>.

In some examples, such as the examples shown in <FIG> and <FIG>, expandable member <NUM> may resemble a stent-like structure that includes a tubular body comprising a plurality of struts <NUM> (e.g., an individual straight portion of an undulating ring) that are interconnected via one or more connections at adjacent vertices <NUM> (peaks or valleys) to define a plurality of cells <NUM> between adjacent struts <NUM>, such as diamond-shape cells or other cell designs. In general, each of the struts <NUM> of expandable member <NUM> may be a substantially straight portion (e.g., a straight or nearly straight member) that may join with one or more other struts <NUM> at a respective vertex <NUM>. Struts <NUM> may be forced apart and radially outward from one another (e.g., via straightening of the undulating rings) to increase the diameter at various portions of expandable member <NUM>. In other examples, expandable member <NUM> may include an expandable braid, an expandable mesh (e.g., woven sleeve or woven tubular structure), or other design.

Expandable member <NUM> can be configured to facilitate thrombus removal. In examples in which catheter <NUM> is used with an aspiration procedure (e.g., ADAPT technique), the size and shape of expandable member <NUM> may enable catheter <NUM> to better engage a thrombus by increasing the distal opening <NUM> into which the thrombus may be received, increasing the total aspiration force exerted on the thrombus via a larger luminal area, and/or by distributing the aspiration forces over a greater portion of the thrombus rather than a localized area, thereby allowing the thrombus to be aspirated into catheter <NUM> more effectively. Expandable member <NUM> enables catheter <NUM> to maintain a relatively small diameter elongated body <NUM> (e.g., within proximal body portion 16A) to facilitate navigability of catheter <NUM>, while also enabling catheter <NUM> to exhibit improved engagement and suction force characteristics that may be attributed to having a large-diameter distal end 10B. In some examples, the presence of expandable member <NUM> may lead to improved revascularization success rates, such as due to the improved thrombus engagement and/or suction (e.g., to better pull the entirety of the thrombus into catheter <NUM> during aspiration) as described herein.

In addition, expandable member <NUM> can be configured to exhibit a relatively low longitudinally compressive stiffness, which can facilitate thrombus removal. For example, when combined with cyclical aspiration, in which suction force applied to inner lumen <NUM> of catheter <NUM> is varied over time, the relatively low longitudinally compressive stiffness of expandable member <NUM> may enable the expandable member <NUM> to undergo "flutter"-type motion, in which expandable member <NUM> alternatingly contracts and expands in an axial direction (e.g., parallel to longitudinal axis <NUM>), e.g. at a periodic frequency. This cyclical longitudinal contraction and expansion of expandable member <NUM> can in turn cause cyclical axial motion of the distal mouth <NUM> relative to the (stationary or relatively stationary) thrombus, which may facilitate dislodgment of the thrombus from vasculature. Additionally, as the expandable member <NUM> contracts longitudinally rather than radially in response to the application of cyclical aspiration, distal mouth <NUM> of expandable member <NUM> may remain more open and engaged with the thrombus, thereby further facilitating removal of the thrombus.

Expandable member <NUM> may be of any suitable length and diameter, which may be selected based on the target vessel or particular procedure being performed. For example, expandable member <NUM> may be made be long enough to fully engulf a thrombus (e.g., an average amount of thrombus material), but short enough to avoid excessive friction between an outer surface of expandable member <NUM> and an inner surface of an introducer sheath or an outer catheter. In some examples, expandable member <NUM> may be about <NUM> centimeters to about <NUM> centimeters long, measured in a direction parallel to longitudinal axis <NUM>. For example, expandable member <NUM> may be about <NUM>, about <NUM>, or about <NUM> in length, such as from about <NUM> to about <NUM>.

As discussed above, in some examples, in the collapsed state, a distal section of expandable member <NUM> may have a cross-sectional dimension substantially equal to (e.g., equal to or nearly equal to) or less than the outer diameter of elongated body <NUM> proximate to expandable member <NUM>. In some examples in which expandable member <NUM> defines a tube shape or a cylinder shape (having an open distal mouth <NUM>) in an expanded state, expandable member <NUM> may define a substantially constant diameter (e.g., constant or nearly constant in the absence of forces compressing expandable member <NUM>) along about <NUM> to about <NUM>, or <NUM> to about <NUM> of a length of expandable member <NUM>, which can be a distal-most length in some examples. The length of expandable member <NUM> can be selected to be long enough to engulf a thrombus, but short enough to enable catheter <NUM> to be inserted into and/or withdrawn from a patient via an outer sheath. An expandable member that is too long may exert too much friction that interferes with movement of catheter <NUM> into or out of a patient via a sheath.

In some examples, in the expanded configuration, distal end 10B of expandable member <NUM> is larger than the outer diameter of elongated body <NUM>, but smaller than the inner diameter of the target vasculature of the patient, such that expandable member <NUM> may be advanced through the vasculature of the patient while in the expanded configuration. Expandable member <NUM> may, for example, be configured to be in an expanded configuration within the vasculature of a patient without engaging with the vessel walls around an outer perimeter of expandable member <NUM>, which may facilitate navigation of the expanded expandable member <NUM> through the vasculature. In some examples, distal end 10B of expandable member <NUM> may be about <NUM> percent to about <NUM> percent of the diameter of the proximal end of expandable member <NUM>. In some examples, the expanded outer diameter or the cross-sectional dimension of expandable member <NUM> at distal end 10B may be about <NUM> percent to about <NUM> percent of the diameter of elongated body <NUM>. As one illustrative example, catheter <NUM> may include an elongated body <NUM> with an inner diameter of about <NUM> inches (about <NUM>) and an outer diameter of about <NUM> inches (about <NUM>), and an expandable member <NUM> having, in the expanded configuration, a maximum inner diameter of about <NUM> inches (about <NUM>) and a maximum outer diameter of about <NUM> inches (about <NUM>), corresponding to an expansion of the diameter of expandable member <NUM> to about <NUM> percent of the diameter of elongated body <NUM>. In other examples, expandable member may expand to about <NUM> percent, <NUM> percent, <NUM> percent, or another larger percentage of the outer diameter or cross-sectional dimension of a portion of elongated body <NUM>.

In some examples, the expandability of expandable member <NUM> at distal tip or portion <NUM> may allow the cross-sectional dimension of elongated body <NUM> within proximal body portion 16A to remain comparatively small. As described above, such a combination may allow catheter <NUM> to exhibit the improved navigability characteristics of a catheter body with a small diameter while still providing catheter <NUM> with the improved engagement and suction characteristics that may be attributed to having a large-diameter distal end 10B.

In some examples, an inner surface of expandable member <NUM> may comprise a surface treatment configured to promote at least one of mechanical or chemical engagement between the inner surface and the thrombus, and enable the thrombus to be pulled into lumen <NUM> of catheter <NUM> more effectively. For example, a coating may be applied to portions of the inner surface of expandable member <NUM> (e.g., the inner surface of the struts or braided filaments, or a flexible membrane <NUM> if present), where the coating has a relatively high clot affinity. Such affinity may be measured, for example, with a dynamic mechanical analyzer (DMA) equipped with a shear sandwich clamp. Examples of suitable coating materials to increase the affinity of the thrombus to expandable member <NUM> may include, for example, a thermoplastic elastomer such as ChronoPrene™ (AdvanSource Biomaterials, Wilmington, Massachusetts), ChronoPrene™ (AdvanSource Biomaterials, Wilmington, Massachusetts), ChronoPrene™ 5A, ChronoPrene™ 15A; a polyolefin elastomer such as ethylene-octene or ethylene-butene copolymer, for example, ENGAGE™ Polyolefin Elastomers (Dow Chemical Company, Midland, Michigan), ENGAGE™ <NUM>, <NUM>, <NUM>; or the like.

As another example, portions of the inner surface of expandable member <NUM> may be textured via etching or otherwise roughened (or rougher) in comparison to the outer surface of the expandable member <NUM> to better mechanically engage the thrombus. In some examples, an inner surface of expandable member <NUM> can include a polymer that is etched to promote mechanical thrombus engagement.

In some examples, thrombus engagement with expandable member <NUM> may be enhanced by delivering electrical energy to expandable member <NUM>. For example, a source of electrical energy (e.g., an electrical signal generator) may deliver an electrical signal to expandable member <NUM> via one or more electrical conductors (not shown) electrically coupled to expandable member <NUM>. The electrical energy may be positively charged to electrostatically engage a thrombus. Characteristics of the electrical energy may be adjusted to better engage the thrombus, such as polarity, or an amount or type of current delivered. For example, pulsed direct current may be employed, optionally with a non-square and/or non-negative waveform. The electrical conductors can extend through inner lumen 26B of elongated body <NUM>, can extend along an outer surface of elongated body <NUM>, can be embedded in a wall of elongated body <NUM>, or have any other suitable configuration.

Expandable member <NUM> may expand from a collapsed configuration to an expanded configuration using any suitable technique. In some examples, expandable member <NUM> may be balloon-expandable. For example, once elongated body <NUM> is positioned within the vessel of a patient adjacent a target treatment site, a balloon (not shown) may be introduced through lumen <NUM> of catheter <NUM> and inflated to radially expand expandable member <NUM> from a collapsed configuration to an expanded configuration. Once in the expanded configuration, expandable member <NUM> may maintain its shape to allow the balloon to be deflated and removed. Expandable member <NUM> may then be collapsed for removal from the vessel of the patient by, for example, pulling elongated body <NUM> or at least expandable member <NUM> into an outer sheath having an inner lumen with a diameter less than the outer diameter of an expanded expandable member <NUM>. The outer sheath may apply an inward force to expandable member <NUM> as expandable member <NUM> is retracted proximally into the outer sheath.

In other examples, expandable member <NUM> may be configured to self-expand. For example, the expandable frame of expandable member <NUM> may be formed from a metal, and may include a shape-memory material such as Nitinol (and, optionally, additional material(s) or metal(s) such as radiopaque material(s) or metal(s)). In some such examples as described further below, an outer sheath can be positioned over expandable member <NUM> to retain expandable member <NUM> in a collapsed configuration, e.g., during navigation of elongated body <NUM> to a target treatment site within the vasculature of a patient. Once at the target treatment site, the outer sheath can be retracted or elongated body <NUM> may be extended distally outward from the sheath to allow expandable member <NUM> to self-expand. In other examples, catheter <NUM> may be navigated through vasculature with expandable member <NUM> in an expanded state.

In other examples, an electrical energy may be used to expand expandable member <NUM>. For example, expandable member <NUM> (or a portion or a layer thereof) may be formed from a material or metal that bends or deflects in response to a current passed therethrough (or to heat generated as a result of such current). One such type of material is shape memory alloy actuator material, e.g. nitinol or Flexinol™ available from Dynalloy, Inc. of Irvine, California USA.

Hub <NUM> may be positioned at (e.g., proximal to or at least partially overlapping with) a proximal body portion 16A of elongated body <NUM>. Proximal end 14A of hub <NUM> may define the catheter proximal end 10A of catheter <NUM> and may include an opening <NUM> aligned with inner lumen 26B of elongated body <NUM>, such that inner lumen 26B of elongated body <NUM> may be accessed via opening <NUM> and, in some examples, closed via opening <NUM>. For example, hub <NUM> may include a luer connector, a hemostasis valve, or another mechanism or combination of mechanisms for connecting hub <NUM> to another device such as a vacuum source for performing the aspiration techniques described herein. In some examples, proximal end 10A of catheter <NUM> can include another structure in addition to, or instead of, hub <NUM>.

In some examples, inner liner <NUM> of elongated body <NUM> defines at least a portion 26B of inner lumen <NUM> of catheter <NUM>, inner lumen 26B defining a passageway through elongated body <NUM>. In some examples, inner lumen 26B may extend over the entire length of inner liner <NUM> (e.g., from proximal end 12A of elongated body <NUM> to the distal end 12B). Inner lumen 26B may be sized to receive a medical device (e.g., another catheter, a guidewire, an embolic protection device, a stent, or any combination thereof), a therapeutic agent, or the like. Elongated body <NUM>, alone or with inner liner <NUM> and/or other structures, may define a single inner lumen <NUM>, or multiple inner lumens (e.g., two inner lumens or three inner lumens 26A-26C) of catheter <NUM>.

Inner lumen 26B formed at least by inner liner <NUM> may define the inner diameter of elongated body <NUM>. The diameter of inner lumen 26B (as measured in a direction perpendicular to a longitudinal axis <NUM> of elongated body <NUM>) may vary based on the one or more procedures with which catheter <NUM> may be used. In some examples, the diameter of inner lumen 26B of elongated body <NUM> may be substantially constant (e.g., constant or nearly constant) from proximal end 12A to distal end 12B or may taper (gradually or more step-wise) from a first inner diameter at proximal end 12A to a second, smaller inner diameter at distal end 12B. As described further below, the inner diameter of expandable member <NUM> may be larger than the inner diameter of elongated body <NUM> proximal to expandable member <NUM> while expandable member <NUM> is in an expanded configuration.

Inner liner <NUM> may be formed using any suitable material, such as, but not limited to, polytetrafluoroethylene (PTFE), expanded PTFE (ePTFE, e.g., unidirectional ePTFE or bi-directional ePTFE), a fluoropolymer, perfluoroalkyoxy alkane (PFA), fluorinated ethylene propylene (FEP), polyolefin elastomers or any combination thereof. A unidirectional ePTFE may be stretched in one of the longitudinal or radial directions, and a bi-directional ePTFE may be stretched in both the longitudinal and radial directions. Other examples of materials from which inner liner <NUM> may be formed include, but are not limited to, Low Density Polyethylene (LDPE) (e.g., about 42D), a PTFE having a durometer of about 60D, High Density Polyethylene (HDPE), or any combination thereof. Some such polyolefin materials may have similar coefficients of friction as PTFE and may be conducive to processing.

In some examples, one or more portions of the inner surface of inner liner <NUM> defining inner lumen 26B (and in some examples, the inner surface of expandable member <NUM> defining inner lumen 26C) may be lubricious to facilitate the introduction and passage of a medical device (e.g., another catheter, a guide member, an embolic protection device, a stent, a thrombectomy device, or any combination thereof), a therapeutic agent, a thrombus, or the like, through lumen 26B. A lubricious inner liner <NUM> may also enable relatively easy tracking of elongated body <NUM> over a guide member (e.g., a guidewire or a microcatheter). In some examples, the material from which portions of inner liner <NUM> is formed may itself be lubricious (e.g., PTFE). In addition to, or instead of, being formed from a lubricious material, in some examples, an inner surface of inner liner <NUM> is coated with a lubricious coating such as a hydrophilic coating.

Elongated body <NUM> includes one or more structural support members <NUM> positioned over inner liner <NUM>. Structural support member <NUM> is configured to increase the structural integrity of elongated body <NUM> while allowing elongated body <NUM> to remain relatively flexible. For example, structural support member <NUM> may be configured to help elongated body <NUM> substantially maintain its cross-sectional shape (e.g., circular or nearly circular) or at least help prevent elongated body <NUM> from buckling or kinking as it is navigated through tortuous anatomy. Additionally, or alternatively, structural support member <NUM>, together with inner liner <NUM>, and outer jacket <NUM>, may help distribute both pushing and rotational forces along a length of elongated body <NUM>, which may help prevent kinking of elongated body <NUM> upon rotation of body <NUM> or help prevent buckling of body <NUM> upon application of a pushing force to body <NUM>. As a result, a clinician may apply pushing forces, rotational forces, or both, to the proximal portion of elongated body <NUM>, and such forces may cause a distal portion of elongated body <NUM> to advance distally, rotate, or both, respectively.

Structural support member <NUM> may include one or more tubular braided structures, one or more coil members defining a plurality of turns, e.g., in the shape of a helix, or a combination of one or more braided structures and one or more coil members. Thus, although the examples of the disclosure primarily describe structural support member <NUM> as a coil, in other examples, catheter <NUM> may include a braided structure instead of a coil, a braided structure in addition to a coil, or a combination that includes one or more of each structure. As one example, a proximal portion of structural support member <NUM> may include a braided structure and a distal portion of structural support member <NUM> may include a coil member.

Structural support member <NUM> can be made from any suitable material, such as, but not limited to, a metal (e.g., a nickel titanium alloy (Nitinol), stainless steel, tungsten, titanium, gold, platinum, palladium, tantalum, silver, or a nickel-chromium alloy, a cobalt-chromium alloy, or the like), a polymer, a fiber, or any combination thereof. In some examples, structural support member <NUM> may include one or more metal wires braided or coiled around inner liner <NUM>. The metal wires may include round wires, flat-round wires, flat wires, or any combination thereof.

In other examples, structural support member <NUM> may include a spiral-cut hypotube that is positioned over inner liner <NUM>. Structural support member <NUM> may extend along only a portion of a length of elongated body <NUM> and is positioned proximal to expandable member <NUM>. In some examples, the distal end of structural support member <NUM> may abut the proximal end of expandable member <NUM> and may be coupled to expandable member <NUM> (e.g., mechanically coupled or bonded with adhesive, or welded). In other examples, expandable member <NUM> may not be coupled to structural support member <NUM> or may not be in direct contact (e.g., abutting contact) with structural support member <NUM>, although the two members may be in the same radial layer of elongated body <NUM> (and/or have the same inner diameter and/or outer diameter where structural support member <NUM> and expandable member <NUM> meet or come closest to each other in the longitudinal direction). For example, the distal end of structural support member <NUM> may be adjacent to the proximal end of expandable member <NUM> but separated by a small gap. In such examples, structural support member <NUM> and expandable member <NUM> may be in the same radial layer and inner liner <NUM>, outer jacket <NUM>, or both may secure both expandable member <NUM> and structural support member <NUM> in place along elongated body <NUM>.

In some examples, structural support member <NUM> may be coupled, adhered, or mechanically connected to at least a portion of an outer surface of inner liner <NUM>. For example, structural support member <NUM> may be positioned over inner liner <NUM> and secured in place (e.g., fixed) relative to inner liner <NUM> by outer jacket <NUM> using a melt-reflow/heat shrink process, via adhesives or other suitable technique.

Additionally or alternatively, structural support member <NUM> may be secured to inner liner <NUM> with the assistance of a support layer (not shown) that helps adhere structural support member <NUM> to one or both of inner liner <NUM> and outer jacket <NUM>. The support layer may include a thermoplastic material or a thermoset material, such as a thermoset polymer or a thermoset adhesive that bonds to inner liner <NUM>, outer jacket <NUM>, or both. In some cases, the material forming the support layer may have elastic properties, such that there may be a tendency for the support layer to return to a resting position. In some examples, the support layer is positioned over the entire length of structural support member <NUM> and inner liner <NUM>. In other examples, the support layer is only positioned over a part of the length of structural support member <NUM> and inner liner <NUM>.

Elongated body <NUM> can also include outer jacket <NUM> positioned over structural support member <NUM> and inner liner <NUM>, the structural support member <NUM> being positioned between portions of inner liner <NUM> and outer jacket <NUM>. In some examples, outer jacket <NUM> may be positioned around structural support member <NUM> such that outer jacket <NUM> covers at least a part or all of both inner liner <NUM> and structural support member <NUM>. Outer jacket <NUM>, together with inner liner <NUM> and structural support member <NUM>, may be configured to define elongated body <NUM> having the desired structural characteristics (e.g., flexibility, kink resistance, torque responsiveness, structural integrity, pushability, and column strength, which may be a measure of a maximum compressive load that can be applied to elongated body <NUM> without taking a permanent set). For example, outer jacket <NUM> may have stiffness characteristics that contribute to the desired stiffness profile of elongated body <NUM>.

In some examples, outer jacket <NUM> may be formed to have a stiffness that decreases from a proximal end 12A of elongated body <NUM> toward distal end 12B. The lowered stiffness of outer jacket <NUM> within the distal body portion 16B of elongated body <NUM> may improve the flexibility and navigability of catheter <NUM> through tortious vasculature of the patient, while the relatively higher stiffness of outer jacket <NUM> within the proximal body portion 16A of catheter <NUM> may provide better pushability or kink resistance. In some examples, outer jacket <NUM> may be formed from two or more different materials with different mechanical properties that enable outer jacket <NUM> to exhibit the desired stiffness characteristics. In some examples outer jacket <NUM> may define a stiffness that is greater than the stiffness of flexible membrane <NUM> of expandable member <NUM>.

In some examples, outer jacket <NUM> may be formed using any suitable material including, but are not limited to, polymers, such as a polyether block amide (e.g., PEBAX®, commercially available from Arkema Group of Colombes, France), an aliphatic polyamide (e.g., Grilamid®, commercially available from EMS-Chemie of Sumter, South Carolina), another thermoplastic elastomer (e.g., a thermoplastic, elastomeric polymer configured to accommodate radial expansion of expandable member <NUM>), polyurethanes, polyamides, or other thermoplastic material, or combinations thereof.

Outer jacket <NUM> may be heat shrunk around structural support member <NUM> and, in some examples, at least a portion (e.g., a proximal portion) of expandable member <NUM> to secure the two members <NUM>, <NUM> in the same radial layer. In some examples, during the heat shrinking of outer jacket <NUM> around structural support member <NUM>, the material of outer jacket <NUM> may flow into at least some of the inner spacings or gaps (e.g., gaps between the adjacent turns of the coils, or between the struts or braids) within structural support member <NUM> or expandable member <NUM> such that portions of outer jacket <NUM>, structural support member <NUM>, and/or expandable member <NUM> form a laminated structure.

In some examples, at least a portion of an outer surface of outer jacket <NUM> and/or expandable member <NUM> includes one or more coatings, such as, but not limited to, an anti-thrombogenic coating, which may help reduce the formation of thrombi in vitro, an anti-microbial coating, and/or a lubricating coating. In some examples, the lubricating coating may be configured to reduce static friction or kinetic friction between elongated body <NUM> and tissue of the patient as elongated body <NUM> is advanced through the vasculature. In addition, or instead, in some examples, the lubricating coating may be configured to reduce static or kinetic friction between elongated body <NUM> and another catheter through which elongated body <NUM> may be inserted. The lubricating coating can be, for example, a hydrophilic coating. In some examples, the entire working length of elongated body <NUM> (from distal end 14B of hub <NUM> to the distal end of outer jacket <NUM>) may be coated with the hydrophilic coating. In other examples, only a portion of the working length of elongated body <NUM> coated with the hydrophilic coating. This may provide a length of elongated body <NUM> distal from distal end 14B of hub <NUM> with which the clinician may grip elongated body <NUM>, e.g., to rotate elongated body <NUM>, pull elongated body <NUM> when removing elongated body <NUM> from the patient, or push elongated body <NUM> through vasculature.

Although a coating or another material may be applied over the outer surface of outer jacket <NUM>, outer jacket <NUM> may still substantially define shape and size of the outer surface of elongated body <NUM>. In some examples, the outer diameter of elongated body <NUM> may be substantially constant (e.g., constant or nearly constant) along the length of elongated body <NUM>. In other examples, the outer diameter of elongated body <NUM> may taper from the first outer diameter within proximal body portion 16A of elongated body <NUM> to a second outer diameter at a point proximate to the proximal end of expandable member <NUM>.

In some examples, expandable member <NUM> may be mechanically coupled to structural support member <NUM> and/or layered between (at least in a proximal portion of the expandable member <NUM>) inner liner <NUM> and outer jacket <NUM>. For example, expandable member <NUM> and structural support member <NUM> can be formed independently of one another, and the proximal end of expandable member <NUM> may be coupled to the distal end of structural support member <NUM>. In some examples, expandable member <NUM> and structural support member <NUM> may be joined via welding, brazing, soldering, adhesives, epoxy, or other suitable technique. In some examples, expandable member <NUM> may be welded, soldered, bonded, or hooked to structural support member <NUM>. In some examples, expandable member <NUM> comprises a plurality of struts <NUM> that define a plurality of cells <NUM>. One or more of the proximal peaks of the proximal-most strut (e.g., at the proximal end of expandable member <NUM>) may be coupled to structural support member <NUM> such that expandable member <NUM> is mechanically coupled to structural support member <NUM> at a plurality of circumferential positions around structural support member <NUM>, such as shown in <FIG>. In some examples, expandable member <NUM> may be bonded (e.g., glued), hooked (e.g., mechanically interlocked), or coupled to structural support member <NUM> using other means.

In some examples, structural support member <NUM> and expandable member <NUM> may be integrally formed. In some such examples, at least a proximal portion 20A of expandable member <NUM> and structural support member <NUM> form the same radial layer of catheter <NUM>, or in other words, are radially equidistant from central longitudinal axis <NUM>. For example, structural support member <NUM> may include a plurality of wires (e.g., coils or braids) that are subsequently woven to form expandable member <NUM>, such that the manufacture may not necessarily require welding or other assembly or connection of expandable member <NUM> to structural support member <NUM>. In other examples, structural support member <NUM> and expandable member <NUM> may be formed using the same hypotube; the proximal portion of the hypotube being spirally cut to form a somewhat coil-like structure (e.g. structural support member <NUM>) while the distal portion of the hypotube is cut to form a plurality of interconnected struts that form expandable member <NUM>.

Additionally, or alternatively, expandable member <NUM> may be at least partially secured to structural support member <NUM> via inner liner <NUM> and/or outer jacket <NUM>. For example, expandable member <NUM> may not be directly coupled to structural support member <NUM> or may not be in direct contact (e.g., abutting contact) with structural support member <NUM>, although the two members may be in the same radial layer of catheter <NUM>. In an example, expandable member <NUM> may be positioned adjacent to structural support member <NUM> over inner liner <NUM>, and outer jacket <NUM> may be positioned over expandable member <NUM> and structural support member <NUM>. Outer jacket <NUM> may be heat shrunk over the two members such that outer jacket <NUM> secures both expandable member <NUM> and structural support member <NUM> in place relative to inner liner <NUM>. In such examples, expandable member <NUM> may be positioned at least partially between inner liner <NUM> and outer jacket <NUM> (e.g., layered or positioned between an inner and outer flexible membrane <NUM>, wherein flexible membrane <NUM> includes extensions of inner liner <NUM> and outer jacket <NUM>).

For example, at least a proximal portion of expandable member <NUM> may be positioned between inner liner <NUM> and outer jacket <NUM>. One or both of inner liner <NUM> or outer jacket <NUM> may extend over the entire length of expandable member <NUM> or may extend over only a portion of the length of expandable member <NUM>. For example, flexible membrane <NUM> may include a distal portion of inner liner <NUM> extending over only part of the length of expandable member <NUM> leaving portions of expandable member <NUM> exposed to inner lumen 26C. The exposed portions of expandable member <NUM> may provide better engagement with a thrombus and/or prevent distal migration of thrombus from catheter <NUM> due to the texture of expandable member <NUM> or direct electrostatic engagement with expandable member <NUM>. For example, as described herein, elongated body <NUM> may comprise an electrical conductor electrically coupled to expandable member <NUM>, and expandable member <NUM> may be configured to receive an electrical signal via the conductor that causes expandable member <NUM> to electrostatically engage the thrombus. In some examples, expandable member <NUM> may be configured to expand radially outward in response to receiving the electrical signal.

In some examples, both inner liner <NUM> and outer jacket <NUM> terminate proximal to a distal end of expandable member <NUM>. In other examples, inner liner <NUM> and outer jacket <NUM> can have other arrangements relative to expandable member <NUM>.

Expandable member <NUM> may include any suitable arrangement relative to inner liner <NUM>, outer jacket <NUM>, and structural support member <NUM>. For example, <FIG> is a conceptual cross-sectional view of another example of the distal tip or portion <NUM> of catheter <NUM> of <FIG>, where the cross-section is taken through a center of the catheter and along a longitudinal axis <NUM>. As shown in <FIG>, distal tip or portion <NUM> includes distal end 12B of elongated body <NUM> and expandable member <NUM>, including parts of inner liner <NUM>, outer jacket <NUM>, a coiled support member <NUM> ("structural coil <NUM>"), and a braided structural support member <NUM> ("structural braid <NUM>"). Coiled support member <NUM> and structural braid <NUM> are individually or collectively examples of structural support member <NUM> of <FIG> and <FIG>. Accordingly, one or both of coil <NUM> and braid <NUM> may be omitted in practicing the catheter <NUM> of <FIG>, or other catheters disclosed herein.

Expandable member <NUM> can include an expandable frame, e.g. in the form of an expandable, generally tubular weave or braid <NUM> ("expandable braid <NUM>") and a liquid barrier layer, e.g. in the form of a relatively thin and flexible membrane <NUM>, coupled to the expandable frame. In some examples, where both structural coil <NUM> and structural braid <NUM> are present, structural braid <NUM> does not overlap (e.g., in an axial direction parallel to longitudinal axis <NUM>) with expandable braid <NUM>, whereas structural coil <NUM> may overlap with both structural braid <NUM> and expandable braid <NUM>.

In the example shown in <FIG>, flexible membrane <NUM> of expandable member <NUM> includes an inner layer <NUM>, which in some examples, but not all examples, may be a distal extension of inner liner <NUM> of elongated body <NUM> that extends distally to (e.g., to a location radially inward of) at least a proximal portion of expandable member <NUM>, or to a location at or near a distal end of expandable member <NUM>. In some such examples, the distal extension of inner liner <NUM> is adhered or otherwise coupled to the inner surface of expandable member <NUM>, or to the outer surface thereof, or otherwise coupled to expandable member <NUM>.

In some examples, a distal portion of elongated body <NUM> and a proximal portion of expandable member <NUM> includes a tie layer <NUM> configured to retain both a distal portion of outer jacket <NUM> and a proximal portion of expandable member <NUM> in place overtop of inner liner <NUM> and inner layer <NUM> of flexible membrane <NUM>, respectively. However, tie layer <NUM> may be absent in some other examples.

As in the example illustrated in <FIG>, expandable member <NUM> when in its expanded state can have a proximal section 20A, a tapering section 20B, and a distal section 20C. Proximal section 20A can have an inner diameter and/or outer diameter that is substantially equal to the inner and/or outer diameter(s) of distal portion 16B of elongated body <NUM>, even when expandable member <NUM> is in the expanded state as shown in <FIG>. Distal section 20C (e.g., a distal-most section of expandable member <NUM>), when in the expanded state, has a larger inner diameter and outer diameter than distal portion 16B of elongated body <NUM>. Distal section 20C can be configured to be generally cylindrical, with a constant or substantially constant inner diameter and/or outer diameter along its length. The length of distal section 20C can be <NUM> to about <NUM>, or <NUM> to about <NUM>, to facilitate engulfing a thrombus during use (without being so long as to generate unacceptable levels of friction during delivery to a patient through a surrounding catheter or sheath). Expandable member <NUM> (e.g. distal section 20C thereof) can be configured to be self-expanding, e.g. upon advancement beyond the end of a surrounding catheter.

The inside and/or outside diameter of distal section 20C (in the expanded state) can be established by heat-setting expandable braid <NUM> on a generally cylindrical mandrel having a mandrel diameter approximately equal to the desired expanded-state inside diameter of expandable member <NUM>. In this manner, the expanded-state inside and/or outside diameter of distal section 20C can be selected to enable distal section 20C to make firm contact with the vessel wall when expanded, and provide a large distal mouth <NUM> for application of high suction force to a thrombus or other material to be aspirated. However, it can also be desirable not to allow the expanded-state inside and/or outside diameter of distal section 20C to become too large, as this can make it difficult to advance catheter <NUM> through a surrounding catheter or sheath during insertion into a patient (as an aggressively expansive expandable member <NUM> generates high friction forces against the inner wall of the surrounding catheter or sheath). Consequently, the expanded-state outside diameter of distal section 20C can be about <NUM> percent to about <NUM> percent of the outside diameter of distal portion 16B of elongated body <NUM> (or of the outside diameter of proximal section 20A of expandable member <NUM>). In some examples, the expanded-state outer diameter of distal section 20C can be about <NUM> percent, <NUM> percent, <NUM> percent, <NUM> percent, <NUM> percent, or <NUM> percent of the outside diameter of distal portion 16B of elongated body <NUM> (or of the outside diameter of the proximal end of expandable member <NUM>). In some examples, an outer diameter of the distal section 20C (e.g., a cylindrical tube) is no more than <NUM> percent of the outer diameter of the distal body portion 16B.

<FIG> are conceptual cross-sectional views of two examples of expandable member <NUM> of <FIG>, where the cross-section is taken through a center of the respective expandable member and along longitudinal axis <NUM>. <FIG> depicts example expandable member <NUM>, which can be an example of expandable member <NUM> of <FIG>. Expandable member <NUM> includes a plurality of elongated filaments <NUM> that are braided (e.g., interwoven) together to form a cylindrical or tubular structure (e.g., a structure defining a lumen 26C within). Some or all of elongated filaments <NUM> can include at least two different materials, at least one of which is radiopaque. For example, some or all of filaments <NUM> may include an outer tube <NUM> comprising a first material, surrounding an inner core <NUM> comprising a second material, wherein either the first material of the outer tube <NUM>, the second material of the inner core <NUM>, or both, is radiopaque. In examples in which the first material of the outer tube <NUM> is radiopaque, the first material may be more radiopaque than the second material of the inner core <NUM>. In examples in which the second material of the inner core <NUM> is radiopaque, the second material may be more radiopaque than the first material of the outer tube <NUM>. In examples in which both the first material and the second material are radiopaque, the first material and the second material may have the approximately the same or different radiopacities.

As one illustrative example, one or more of the elongated filaments <NUM> of the expandable frame (when braided or woven) may include a drawn-filled tube (DFT) including an outer tube <NUM> comprising a nickel-titanium alloy (e.g., Nitinol), or stainless steel, or a cobalt-chromium alloy, surrounding an inner core <NUM> made of a second material that is radiopaque, for example, a material that is more radiopaque than Nitinol, stainless steel or cobalt-chromium alloy (e.g., more radiopaque than the first material). In some examples, the radiopaque second material of the inner core <NUM> comprises platinum or a platinum alloy. The nickel-titanium alloy may provide expandable member <NUM> with the desired mechanical strength and shape memory, while platinum or other more radiopaque material provides expandable member <NUM> with the desired radiopaque properties.

As another non-limiting, illustrative example, one or more of the elongated filaments <NUM> may include an outer tube <NUM> comprising a first material, e.g., a gold plating, covering the exterior surface of an inner core <NUM> comprising a second material, e.g., a Nitinol wire. For example, the first material may be added to an exterior surface of the second material via electro plating or another suitable technique. In some such examples, the first material of the outer tube <NUM> is more radiopaque than the second material of the inner core <NUM>. However, these examples are not intended to be limiting. Some or all of elongated filaments <NUM> may include any two suitable materials in which an outer tube <NUM> comprising the first material is disposed radially outward from an inner core <NUM> comprising the second material, and at least one of the two materials is radiopaque and more radiopaque than the other material. In this configuration of expandable member <NUM>, the at least one radiopaque material extends throughout a substantial portion of the axial or longitudinal length of expandable member <NUM> (e.g., along central longitudinal axis <NUM>), thereby enabling expandable member <NUM> to be radiopaque along its length.

In other examples, such as examples in which the radiopaque material is added via electroplating, the radiopaque material may be placed only at certain locations or intervals along the length of expandable member <NUM>, rather than along the entire axial length. For example, expandable member <NUM> may include a relatively short (e.g., about <NUM>-long) section of gold plating (or other outer material <NUM>) placed at periodic intervals (e.g., at every <NUM>-long interval) along the axial length of the "core" material <NUM>. Some such examples may allow more flexibility of the structural supports (e.g., the inner core <NUM>), compared to examples in which the entire inner core <NUM> is plated or otherwise covered with outer tube <NUM>.

<FIG> depicts another example expandable member <NUM>, which is an example of expandable member <NUM> of <FIG>. Expandable member <NUM> includes a first plurality of elongated filaments <NUM> that are braided (e.g., interwoven) with a second plurality of elongated filaments <NUM> to form a cylindrical or tubular structure (e.g., a structure defining a lumen 26C within). Each elongated filament of the first plurality <NUM> comprises a first material, and each elongated filament of the second plurality <NUM> comprises a second material, wherein either the first material, the second material, or both is radiopaque. Regardless of whether the second material is radiopaque, however, the first material of the first plurality <NUM> is more radiopaque than the second material of the second plurality <NUM> to provide expandable member <NUM> with the desired radiopacity properties. The first material extends throughout the axial or longitudinal length of expandable member <NUM>, enabling the advantages of catheter <NUM>, as described above with respect to <FIG> and <FIG>.

As one illustrative example of expandable member <NUM>, elongated filaments of the first plurality <NUM> comprise a first material, such as platinum or platinum alloy, and elongated filaments of the second plurality <NUM> comprise a second material, such as Nitinol, stainless steel or cobalt-chromium alloy. However, this example is not intended to be limiting.

<FIG> illustrate liquid impermeable layer or flexible membrane <NUM>, which can be, for example, radially inward of the expandable frame of the respective expandable member <NUM>, <NUM>, <NUM> (e.g., defining an innermost surface of the expandable member), radially outward of the respective expandable member <NUM>, <NUM>, <NUM> (e.g., defining an outermost surface of the expandable member), or any combination thereof. Membrane <NUM> can be configured to help ensure that catheter <NUM> can maintain vacuum pressure when the expandable member is engaged with a thrombus, and also to prevent leakage from inner lumen 26C of the expandable member. Membrane <NUM> may have a relatively low flexural stiffness to allow for easy bending, and relatively high elongation properties such that the respective expandable member may be necked down (e.g., collapsed into a contracted or delivery configuration) to fit into a sheath (<FIG>). Some example materials for flexible membrane <NUM> include polymers such as, but not limited to, polyether-based thermoplastic polyurethanes (TPUs) (e.g., Tecoflex™ or Tecothane™, both available from the Lubrizol Corporation of Wickliffe, Ohio; or Polyblend™, available from Custom Building Products of Santa Fe Springs, California), olefin block copolymer elastomer (available from RTP Company of Winona, Minnesota, or from Foster Corporation of Putnam, Connecticut), silicone, or other similar materials. In some examples, membrane <NUM> is formed from a fluid-impermeable polymer.

In some examples, flexible membrane <NUM> is formed from a softer, more flexible material than inner liner <NUM> and/or outer jacket <NUM> to enable expandable member <NUM> to accommodate the expansion of expandable member <NUM>. In some examples, flexible membrane <NUM> may have a lower coefficient of friction and/or a lower modulus of elasticity, than inner liner <NUM>. The stiffness of flexible membrane <NUM> can be measured by, for example, a flexural stiffness or a torsional stiffness value. An inner liner <NUM> which is more stiff than membrane <NUM> may enable catheter <NUM> to exhibit a more flexible tip while still retaining sufficient strength and rigidity throughout the majority of elongated body <NUM> for navigation.

In some examples, the one or more materials from which flexible membrane <NUM> is formed may be selected to provide better engagement (e.g., mechanical or chemical engagement) with the thrombus. Additionally or alternatively, flexible membrane <NUM> may include a surface treatment that provides better engagement with a thrombus (e.g., mechanical or chemical engagement).

In some examples, membrane <NUM> may be formed by reflowing an extruded tube over the braided or coiled structure of the expandable frame of the respective expandable member, or may be formed by dip-coating the expandable frame into the desired material of membrane <NUM>. In some examples, membrane <NUM> may include a hydrophilic coating on an exterior surface of membrane <NUM> to provide lubricity for navigating the patient's vasculature.

In some examples, instead of or in addition to the more-rigid structure elements (e.g., outer tube <NUM>, inner core <NUM>, first filaments <NUM>, and/or second filaments <NUM>) of expandable member <NUM> being radiopaque, membrane <NUM> may itself include a radiopaque material, such as, but not limited to, one or more of Tungsten, Bismuth Subcarbonate, Tantalum, or Barium Sulfate. For example, in some cases, some or all of the radiopaque visibility of expandable member <NUM> may be derived from the membrane <NUM>, reducing or abrogating the need for the more-rigid support structure of expandable member <NUM> to be radiopaque at all. As one illustrative example, membrane <NUM> may include a thermoplastic elastomer (TPE) that is combined (e.g., compounded) with a radiopaque material, such as about <NUM>% Tungsten (e.g., <NUM>% Tungsten or nearly <NUM>% Tungsten to the extent permitted by manufacturing tolerances). The thermoplastic elastomer and the radiopaque material may be combined together to define a composite material or a mixture. In other examples, membrane <NUM> may be radiopaque so as to further improve the visibility of expandable member <NUM>. In some examples, membrane <NUM> may include a distal extension of inner liner <NUM> and/or outer jacket <NUM> (<FIG>) of elongated body <NUM>.

In some examples, catheter <NUM> may be introduced into the vasculature of a patient with the aid of an introducer sheath, which defines a pathway from an exterior access point into the vasculature (e.g., a radial artery or a femoral artery of the patient). For example, <FIG> are conceptual cross-sectional side views of expandable member <NUM> of catheter <NUM> (<FIG> and <FIG>) being deployed with the aid of an introducer sheath <NUM>. For illustrative purposes, <FIG> illustrate expandable member <NUM>, and the details of inner liner <NUM>, structural support member <NUM>, and outer jacket <NUM> are not labeled. <FIG> illustrates expandable member <NUM> in a collapsed configuration within introducer sheath <NUM> positioned over expandable member <NUM>. Introducer sheath <NUM> may include a tubular body configured to receive catheter <NUM>.

In some examples, a clinician may position introducer sheath <NUM> from an incision site (e.g., a femoral access site or a radial access site) and into a patient's vasculature and then introduce catheter <NUM> into the vasculature through introducer sheath <NUM>. In some examples, catheter <NUM> is introduced directly into the vasculature via introducer sheath <NUM>. In examples in which expandable member <NUM> is self-expandable, expandable member <NUM> is deployed into the expanded configuration (also referred to herein as a deployed configuration) once it exits a distal opening of introducer sheath <NUM> (as shown in <FIG>). A clinician may then navigate catheter <NUM> through the vasculature of the patient while expandable member <NUM> is already in the deployed configuration shown in <FIG>.

In other examples, catheter <NUM> may be positioned without an outer catheter that holds expandable member <NUM> in a collapsed configuration until the expandable member <NUM> reaches a target site within vasculature of a patient. In some of these examples, a clinician may introduce the outer catheter (in which catheter <NUM> is positioned) into the vasculature via introducer sheath <NUM>.

Catheter <NUM> may be loaded into introducer sheath <NUM> directly or with the aid of an insertion tool <NUM>, an example of which is shown in <FIG>. As described above with respect to <FIG> and <FIG>, an advantage of incorporating a radiopaque material throughout the structure of expandable member <NUM> and eliminating a more rigid solid metal marker band at the distal tip or portion <NUM> of catheter <NUM> is that expandable member <NUM> may be easily necked down or collapsed to fit within introducer sheath <NUM>. As shown in <FIG>, insertion tool <NUM> (also referred to as an "introducer tool" or a "compression tool") is configured to collapse expandable member <NUM> into a collapsed or delivery configuration and enable expandable member <NUM> to fit within an inner lumen of introducer sheath <NUM>. Expandable member <NUM> may be introduced into funnel <NUM> at one end of insertion tool <NUM>, and as expandable member <NUM> is pushed into insertion tool <NUM>, funnel <NUM> collapses expandable member <NUM> into a collapsed configuration.

A clinician may use introducer tool <NUM> to insert expandable member <NUM> into introducer sheath <NUM>, e.g., during a medical procedure or in preparation for the medical procedure. The clinician may, for example, use introducer tool <NUM> to collapse expandable member <NUM> (or expandable member <NUM> may be preloaded within introducer tool <NUM> at the time of manufacture), and then push distal tip or portion <NUM> of catheter <NUM> from insertion tool <NUM> into proximal end 56A of introducer sheath <NUM> and towards distal end 56B of introducer sheath <NUM>.

Insertion tool <NUM> may be formed from any suitable material, such as, but not limited to, polytetrafluoroethylene (PTFE).

<FIG> is a flow diagram of an example method of aspiration using catheter <NUM> of <FIG> and <FIG>. The techniques of <FIG> include inserting catheter <NUM> into vasculature of the patient (<NUM>), deploying expandable member <NUM> to expand expandable member <NUM> in the vasculature of the patient (<NUM>), and aspirating a thrombus (<NUM>). In some examples, the techniques described herein include removing catheter <NUM> from the vasculature of the patient once the procedure is complete. Throughout the techniques of <FIG>, a clinician may observe a radiopaque material of expandable member <NUM> via fluoroscopic imaging to improve surgical performance and patient outcomes.

A clinician may observe, using fluoroscopic imaging, expandable member <NUM> while distally advancing distal tip or portion <NUM> of catheter <NUM> toward a target site. In some examples, inserting catheter <NUM> into vasculature of a patient (<NUM>) may include initially introducing a guidewire, guide catheter, or another guide member into the vasculature of the patient to a target treatment site. Elongated body <NUM> may then be introduced over the guidewire and advanced to the target treatment site. Additionally, or alternatively, catheter <NUM> may be introduced into vasculature of a patient with the aid of a guide catheter. For example, the guide catheter may be initially introduced into vasculature of a patient and positioned adjacent a target treatment site. Catheter <NUM> may then be introduced through an inner lumen of the guide catheter.

Once within the vasculature, expandable member <NUM> may be deployed into the vasculature (<NUM>). In some examples, expandable member <NUM> may be self-expanding and may expand without the aid of any additional expansion mechanisms once released from introducer sheath <NUM> or another outer sheath. Additionally, or alternatively, expandable member <NUM> may be expanded using a balloon. In other examples, expandable member may be expanded by applying electrical energy to expandable member <NUM>. For example, expandable member <NUM> (or a portion or layer thereof) may be constructed using a shape memory alloy actuator material.

The technique of <FIG> also includes applying a suction force to inner lumen <NUM> of catheter <NUM> to remove a thrombus from the vasculature (<NUM>). For example, once distal tip or portion <NUM> of catheter <NUM> is positioned proximate to a thrombus, a clinician may actuate a suction source to apply a suction force to lumen <NUM>. The suction source can comprise a pump, such as a directacting pump (e.g., a peristaltic pump, or a lobe, vane, gear, or piston pump, or other suitable pumps of this type) or an indirect-acting pump (e.g., a vacuum pump, which creates a partial vacuum in an evacuation volume fluidically coupled to the liquid to be displaced). Due to the radiopacity of expandable member <NUM>, a clinician may observe or determine, using fluoroscopic imagery, a longitudinal or axial contraction of expandable member <NUM> during the aspiration, as well as a shape of expandable member <NUM>, which may indicate that the expandable member <NUM> is in engaged with the thrombus.

In some examples, the suction force applied to inner lumen <NUM> of catheter <NUM> is varied over time, referring to herein as cyclical aspiration. As discussed above, during this cyclical aspiration, expandable member <NUM> may axially compress and expand in response to the varying suction force.

Catheter <NUM> may be removed from the vasculature once the aspiration procedure is complete.

Claim 1:
A catheter (<NUM>) comprising:
an elongated body (<NUM>) comprising a proximal body portion (16A) and a distal body portion (16B), and defining a body inner lumen (26B); and
an expandable member (<NUM>) located at the distal body portion, (16B) the expandable member (<NUM>) defining an expandable member inner lumen (26C), the expandable member inner lumen comprising a distal extension of the body inner lumen (26B),
wherein the expandable member (<NUM>) is configured to expand radially outward and thereby expand the expandable member inner lumen (26C) radially outward,
wherein the expandable member (<NUM>) comprises a plurality of structural elements, one or more of the structural elements of the plurality of structural elements comprising a first material surrounding a core comprising a second material, and
wherein the first material is more radiopaque than the second material, or wherein the second material is more radiopaque than the first material, wherein the expandable member (<NUM>) is configured to self-expand radially outward from a collapsed configuration to an expanded configuration , and wherein, while a suction force is applied to the body inner lumen (26B), the expandable member (<NUM>) is configured to axially contract in response to contact with a thrombus enabling a user to observe, via fluoroscopic imagery, that the catheter (<NUM>) is engaged with the thrombus.