Catheter mouth designs

Abstract

To provide an expandable mouth for a catheter.SOLUTION: An expandable mouth for a catheter provides a large mouth opening for providing sufficient radial direction force while having flexibility to reach and retrieve an occlusive clot. The expandable mouth has a framework which has: a folded state for allowing a clot collection catheter to adapt to an external catheter of a low profile; and an expanded state for contacting a blood vessel wall for sealing or restricting flow on a proximal side. The framework has narrowed segments, undulations, closed cells, and other flexibility enhancing features, and has one or more support arms and a distal curved part. The framework can provide safe and rapid access to complex areas and more reliably remove occlusions while shortening procedure times.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to devices and methods for removing acute occlusions from blood vessels during intravascular medical procedures. More specifically, the present disclosure relates to an expandable tip for a retrieval aspiration catheter.

Background Art

[0002] Suction and thrombus retrieval catheters and devices are often used for mechanical thrombus removal for intravascular intervention when a patient has conditions such as acute ischemic stroke (AIS), myocardial infarction (MI), and pulmonary embolism (PE). In the prior art, access to the neurovascular bed in particular has been difficult because the target blood vessels are of small diameter, far from the insertion site, and highly tortuous.

[0003] To deliver an effective device to the thin, highly branched cerebral arterial system, conventional catheters often require a balance of many factors. The catheter needs to have sufficient flexibility to follow the vascular structure and withstand large bending strains, while also having axial stiffness to provide smooth and stable advancement along the path. In addition, sudden stiffness or geometric changes can interfere with tracking, cause significant stress concentrations, and increase the likelihood of device torsion or buckling.

[0004] Some designs of aspiration-type thrombus retrieval catheters, such as those with a fixed port, may have difficulty guiding complete aspiration of the aspirate to the fluid volume and blood clots distal to the port. When aspirating using a catheter that cannot seal in the target blood vessel, a significant portion of the aspiration flow will come from the vascular fluid proximal to the catheter tip rather than the distal vascular region with the blood clot. This significantly reduces the aspiration efficiency and the success rate of thrombus removal. For example, a firm thrombus rich in fibrin may clog the tip of a conventional fixed-port catheter, often making it difficult to extract. This clogging can cause the soft part of the thrombus to break away from the firm region.

[0005] The design of aspiration catheters featuring a larger or expandable port for efficiency improvement requires a balance between flexibility for delivery, appropriate radial force, and atraumatic deployment. The catheter element not only needs to withstand large mechanical strains acting on it, but also needs to generate sufficient radial force during expansion to prevent it from collapsing under the action of the suction force of aspiration. To meet these requirements, the ports of some aspiration catheters are designed to have a diameter significantly larger than that of typical delivery catheters or sheaths. These designs may not be able to effectively balance competing requirements to be truly effective and safe for a wide range of treatment situations. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] The present design aims to provide an improved retrieval catheter with an expandable distal tip incorporating features to address the above-mentioned drawbacks. MEANS FOR SOLVING THE PROBLEM

[0007] The design herein can be for an expandable distal tip of a thrombus retrieval catheter capable of providing local flow restriction / stop within a target blood vessel with a large port facing the thrombus. The catheter can be flexible enough to navigate very tortuous regions of anatomical structures such as neurovascular vessels to reach the occlusive clot. The expandable distal tip of the catheter may also be compatible with a relatively low-profile access sheath and catheter for delivery advantages.

[0008] The thrombus retrieval catheter can have a substantially tubular support tube that defines a longitudinal axis. The large-diameter catheter central lumen can be configured to allow a guide wire, a microcatheter, a stent retrieval device, and other such devices to pass through. The lumen can also direct suction to the distal end of the catheter. The tubular body can terminate at a distal end, and at the distal end, an expandable tip can be integrally formed or fixedly connected.

[0009] The catheter can have a self-expanding oral framework comprising a plurality of interconnected struts formed in a porous framework. The oral framework can be configured to expand from a folded delivery configuration to an expanded deployment configuration when deployed at the site of an occlusive thrombus. In the expanded deployment configuration, the tip can assume a substantially conical or funnel shape. The funnel shape formed by the tip can improve suction efficiency, stop unnecessary flow, and reduce the risk of vascular trauma due to snagging at the vascular opening.

[0010] In the deployed state, the expandable tip is tapered such that the proximal end of the tip has a first radial dimension and a more distal portion of the tip has a second radial dimension that is larger than the first radial dimension. The second radial dimension may be larger than the diameter of the target blood vessel. At least a portion of the tip can have a radial dimension that is larger than the inner diameter of the outer catheter in the expanded deployment configuration.

[0011] In another embodiment, at least a portion of the struts forming the outer periphery of the oral framework can extend radially inward from the maximum radial dimension of the oral framework in a distal direction such that a maximum radial dimension occurs at an axial position intermediate the proximal and distal ends of the framework. With such a configuration, the tip can contact the blood vessel wall in an expanded state with a large and smooth radius to avoid vascular trauma and reduce friction. When expanded and unconstrained, the diameter of the tip framework can be in the range of 1 mm to 10 mm, preferably close to 3 mm.

[0012] The oral strut framework can be in the cut pattern of stainless steel in the form of sheets or tubes, or a superelastic shape memory alloy such as Nitinol. The struts of the oral framework can be connected to form a closed cell, loop, or undulating pattern. A plurality of distal hoops or crown struts can form the outer periphery of the tip oral opening. One or more support arm struts can extend longitudinally between the proximal and distal ends of the oral framework to connect adjacent hoops that contact the hoop trough, and the support arm can extend proximally from the hoop trough to connect the expandable tip to the support tube and can form a substantially conical surface about the longitudinal axis.

[0013] The catheter body is characterized by a combination of ribs and a spine and can define a substantially tubular shape. The expandable mouth can be formed integrally with the support tube for a monolithic structure, such as by machining the tube and the mouth together from the same hypotube material. In another embodiment, the tubular body can be a metal or polymer braid / mesh or coiled wire structure.

[0014] The support arm can be axisymmetric with the longitudinal axis of the catheter or can be wound or placed helically around the axis. Individual support arms can be attached independently to the most distal rib or can extend from or be aligned with one of one or more axial spines of the support tube. Alternatively, a portion of the support arm can be connected via a slot, stitch, or some other non-rigid connection such that the arm does not add rigidity to the strut framework.

[0015] The struts of the hoop and support arm can also contain features such as constrictions, curves, and / or undulations to enhance or adjust the flexibility of the structure. The support arm can take on a circumferential waveform or sine wave pattern so that it can bend more freely along the axis of the arm. In another case, the strut of the support arm can have a portion that is narrower than another portion of the support arm, or the support arm can have a width different from at least a portion of the width of the distal hoop or crown that forms the outer perimeter of the mouth.

[0016] The struts of the hoop and support arm of the mouth framework can intersect in a plurality of troughs located at various axial and clock positions around the longitudinal axis. The number and location of the trough intersections can, in part, help determine the local rigidity of the framework. For example, the support arm can terminate proximally in a support trough and distally in a hoop trough to form a closed cell. In one example, adjacent support arms can share one or more cells. In another example, the support arm can extend proximally from the intersection with one or more hoops in the hoop trough and terminate at the spine of the support tube, i.e., the most distal rib, to form a closed cell. These cells can help the mouth framework stretch or contract longitudinally under tensile or compressive loads during a thrombectomy procedure.

[0017] When in the delivery configuration with the tip folded, the troughs of the framework can function as hinges around which the strut framework folds. When expanded, the support arms of the mouth framework can form an angle with the longitudinal axis, and this angle determines the taper rate of the conical funnel shape of the expanded tip. The angle can, for example, range from about 10 degrees to about 45 degrees. In another example, the taper can be shallow, and the angle between the support arm and the longitudinal axis can be about 30 degrees.

[0018] The strut framework can be a cut pattern of sheet or tube stainless steel, or a superelastic shape memory alloy such as nitinol. The funnel shape formed by the tip can improve suction efficiency, reduce friction, and reduce the risk of vascular trauma due to snagging at the vascular opening. The funnel shape also means that in the deployed state, the expandable tip is tapered such that the proximal end of the tip has a first radial dimension and a more distal portion of the tip has a second radial dimension that is larger than the first radial dimension. The second radial dimension may be larger than the diameter of the target blood vessel.

[0019] The catheter may further have a radially disposed flexible elastomeric cover so as to form a sleeve around at least a portion of the support tube and the expandable tip of the thrombus retrieval catheter. The cover can be homogeneous or can have multiple layers. Alternatively, the cover can be one or more polymer jackets.

[0020] Another expandable mouth for a thrombus retrieval catheter can have a self-expanding mouth framework disposed around the longitudinal axis. The mouth framework can have a folded delivery configuration when constrained within the outer catheter and delivered to the target site, and an expanded deployed configuration when the outer catheter is retracted and the framework is exposed. The mouth framework can have a plurality of interconnected struts, and the struts can form a petal-like shape circumferentially disposed around the longitudinal axis. Each petal can have struts of longitudinal arms that behave similarly to the support arms described above. The petals can have undulations or variable widths with constrictions to improve flexibility. These features can promote bending and flexion along the axis of each arm. The longitudinal arms can extend individually, or the struts of one or more longitudinal arms can be divided to form one or more closed cells connected by distal hoops. This cell allows the petals to expand independently and avoid the support tube pulling the mouth framework proximally during expulsion of the blood clot.

[0021] The polymer membrane or cover may be disposed on, around, or enclosing the mouth framework such that support is provided to the membrane when the suction force of aspiration is directed through the catheter during a thrombus removal procedure. The cover may be taut such that when the distal end expands to the deployed configuration, the cover expands under the radial force of the mouth framework, or may be loose or slack such that all radial forces can be directed towards the vessel wall.

[0022] The petals of a self-expanding mouth framework can be made more flexible by individually connecting the longitudinal support arms to a trough, connecting struts, common spine, or the most distal rib of a catheter support tube in the proximal direction. The distal peak of each petal may be a crown or hoop member that is not circumferentially connected to the crown of an adjacent petal such that each petal extends independently from its proximal connection(s). As a result, the petals can respond separately to forces and thrombus morphology such that each petal can bend individually without being constrained by adjacent petals.

[0023] In a further example, the expandable mouth of a thrombus retrieval catheter can have a proximal end, a distal end, and a radial strand arrangement that forms a closed cell mesh disposed around a longitudinal axis and extends from the proximal end to the distal end. The mesh arrangement can be made from wire or shape memory alloy such that the mouth can expand from a folded delivery configuration to an expanded deployed configuration. When not constrained by an outer catheter in the expanded deployed configuration, the cell mesh can form a substantially conical surface about the longitudinal axis. As with other examples, a flexible polymer membrane can cover some or all of the closed cell mesh at the catheter tip.

[0024] The closed cell mesh array of the mouth framework may be a continuous polygonal pattern such as triangular or quadrilateral cells connected through the vertices of adjacent cells. The pattern may be one of those commonly seen in stent applications, where a low-invasive mesh is used to support and hold an open blood vessel passage. In one example, an elongated quadrilateral pattern forms cell pores and shows vertices where local arrangement peaks are shared. The pattern can repeat axially and radially, and the most distal arrangement peaks of adjacent pores may be joined by a curved distal hoop or crown to show the outer periphery of the expandable mouth.

[0025] The density of the closed cell mesh pattern can be varied. A higher density mesh can have greater rigidity and radial force, but can also provide more support for the overlying cover or membrane. In one embodiment, the pattern may be of high density such that blood flow across the mesh is blocked by the small diameter pores. In this situation, a membrane cover may not be necessary because the pattern of pores is fine enough to function as a seal that blocks blood within the blood vessel proximal to the tip.

[0026] To enable smooth delivery of the thrombus retrieval catheter through the outer catheter, the outer surface of the closed cell mesh and / or membrane or outer jacket at the tip can be coated with a low-friction material such as PTFE or FEP, or a hydrophilic lubricious material such as those provided by Surmodics, DSM, and Harland Medical. The coating can prevent the accumulation of static or kinetic friction and reduce the risk of catheter movement difficulty or torsion in the tortuous regions of the vasculature.

[0027] Other aspects and features of the present disclosure will become apparent to those skilled in the art by considering the following detailed description in conjunction with the accompanying figures.

Brief Description of the Drawings

[0028] The above and further aspects of the present invention will be further considered with reference to the following description in conjunction with the accompanying drawings, where like reference numerals indicate functionally similar or identical elements. The drawings are not necessarily to scale, and instead, emphasis is placed on illustrating the principles of the present invention. The figures depict one or more implementations of the device of the present invention by way of illustration and not limitation.

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BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The disclosed design aims to create an expandable tip for a thrombectomy catheter that can provide both local flow restriction / deterrence with a large distally facing opening adjusted to provide sufficient radial force and high flexibility to navigate tortuous regions of the vasculature within the outer catheter to reach occlusive blood clots. The large opening design provides substantially higher suction efficiency and flow restriction capabilities. Such advantages can also be particularly beneficial in the case of stroke intervention procedures, where the blood vessels within the neurovascular bed are particularly thin, tortuous, and fragile. As a result, the adjusted axial stiffness and bending stiffness profiles of the expandable tip can prevent torsion and resistance to movement while following through these blood vessels. The tip can have a folded state, whereby the thrombectomy catheter can be compatible with a relatively low-profile access sheath and outer catheter, and thus (in the case of femoral access) can easily and reliably close the puncture wound at the patient's groin. The expandable tip can also comprise an internal and / or external low-friction liner, and an outer polymer jacket or membrane disposed around the support structure. These improvements can lead to safe and more rapid access to complex regions of the catheter and other devices to more reliably remove occlusions and shorten the treatment time.

[0030] Another advantage of using and having a thrombectomy catheter with an expansion port delivered through an outer catheter is that when a blood clot enters the distal end of the thrombectomy catheter, the thrombectomy catheter can be retracted through the outer catheter such that the outer catheter remains in place to maintain access at the target treatment location. It is recognized that in certain thrombi, it may be necessary to retract the outer catheter along with the thrombus and the inner thrombectomy catheter, but most thrombi are likely to be removed through the inner thrombectomy catheter. This combination reduces the risk that potential thrombus residues can dislodge from the catheter during injection of the contrast agent, thus increasing the likelihood that there are no debris in the lumen of the outer catheter. With conventional catheters, the user often had to pay the price of losing access to the target treatment location and flush all thrombus residues out of the body outside the body by removing the outer catheter prior to injection of the contrast agent. The present invention provides means for minimizing the number of catheter advancements required to treat a patient, thereby reducing the potential for blood vessel damage and the associated risk of vessel dissection if multiple passes are required.

[0031] Here, specific examples of the present invention will be described in detail with reference to the figures. As used herein, it should be understood that the tip framework, mouth framework, support frame, etc. are replaceable and all refer to the same structure. The design can often have a polymer membrane cover, which is typically not shown to clarify the underlying framework. These descriptions are often related to mechanical thrombectomy treatment, but the design can be similarly adapted to other procedures and other body passages.

[0032] Regardless of whether it is a coronary vessel, a pulmonary vessel, or a cerebral vessel, accessing various vessels within the vascular system to reach a blood clot involves well-known procedural steps and the use of many conventional commercially available accessory products. These products, such as angiographic materials, rotary hemostatic valves, delivery access catheters, and guidewires, are widely used in examination institutions and medical procedures. If these or similar products are used in conjunction with the disclosure of the present invention in the following description, their functions and exact configurations will not be described in detail.

[0033] Referring to FIG. 1, the thrombus retrieval catheter can have a proximal tubular portion 35 and a distal expandable tip 100 that expands radially when exiting a delivered outer catheter or intermediate catheter. The tip 100 is sized to have an expanded diameter that is approximately the same as or slightly larger than the expected upper end of the diameter of the target vessel when not constrained, as further shown in FIG. 2, and provides a large distal opening 113 for aspirating (including capturing) a blood clot 40 or thrombus. Thus, upon deployment, the opening 113 of the tip 100 aligns with the diameter of the vessel 20 and, when aspiration is applied (as indicated by the arrow), has a radial force that seals the vessel or creates sufficient flow restriction such that blood and the blood clot distal to the opening, rather than the blood proximal to the tip, are drawn into the catheter. If the expanded tip does not seal or forms only a partial seal, the suction force applied to the blood clot may be directed to the region of the vessel and outer catheter 30 where the flow is less likely to be restricted proximal to the tip, resulting in reduced effectiveness. However, even an expandable tip 100 that seals partially is still superior in performance to many current aspiration catheters that leave a larger cross-sectional area open to the vessel proximal to the tip. In other examples, a support tube 35 of the enlarged catheter body or a dedicated sealing portion (not shown) can also be used to occlude the lumen between the thrombus retrieval catheter and the outer catheter 30.

[0034] The support tube 35 of the thrombus retrieval catheter can have many different configurations. The support tube 35 can have one or more axial spines 42 extending along the length of the support tube. For example, the support tube 35 shown in FIG. 1 has two spines spaced 180 degrees apart. The spine(s) can have a tubular or wire structure, providing good axial rigidity for advancing and retracting the catheter while having excellent lateral flexibility for navigating through blood vessels. Using multiple spines promotes bending along a defined plane while reducing the likelihood that the support tube 35 will elongate under tensile load, such as when the expandable tip 100 is drawn into the outer catheter opening. Along the length of the axial spine(s), there may be a support structure defining a series of ribs or a tubular mesh or braid that defines the inner lumen 44 of the support tube 35. The support structure may be a simple circular configuration as shown, or may take a more complex shape as needed, this example being shown with an axially curved profile connected to the spine 42. The substantially cylindrical support tube 35, which does not have a planar cross-section, can have the ability to expand under compression during expulsion of the blood clot, even when covered by an elastomeric cover or jacket, and can "swallow" a high-density blood clot that in another situation may not be able to enter a non-expandable lumen.

[0035] The support tube 35 can be formed by laser cutting a hypo tube or other tube material, or from other similar structures including braids having overlaid or woven spines. This enables the support tube 35 to have good push-in characteristics and torque characteristics, a small bending radius, kink resistance, and reliable resistance to tensile elongation. Commonly used materials include Nitinol, as well as well-known medical grade stainless steel alloys such as 304 and 316. In hypo tubes of different materials such as stainless steel in the proximal portion of the tubular support tube and Nitinol in the distal portion of the tubular support tube and the dilation opening, the different materials are joined by welding, adhesion, or by holding the engagement features in position by means of inner and / or outer polymer jacket materials.

[0036] The funnel-shaped design of the expandable tip 100 of the disclosed embodiment can be an integral lattice laser cut directly and integrally with the support tube 35 of the catheter shaft. Alternatively, the lattice of the expandable tip may be an injection molded support or mesh frame configured as a single piece and attached to the support tube by heat welding, adhesive, or similar means. The tip can be designed to expand to the diameters of a wide range of target blood vessels such as the distal jugular vein (3.2 - 5.2 mm), the horizontal M1 segment of the middle cerebral artery (1.6 - 3.5 mm), and / or the internal carotid artery (ICA, 2.7 - 7.5 mm). When the catheter is then retracted from the M1 segment to the ICA (or to another path having an increasing blood vessel inner diameter in the proximal direction), the expandable tip 100 continues to seal the blood vessel over a range of blood vessel diameters. Further, a tip capable of taking a range of target blood vessel diameters can also seal a blood vessel bifurcation having a larger cross-sectional area than the proximal and distal blood vessels of the bifurcation. Preferably, the expandable tip 100 of the catheter is expanded at the treatment location so that it is not necessary to advance the expanded tip through the blood vessel structure.

[0037] By disposing the expandable tip 100 so as to have a linear connection with one or more of the spines 42 of the support tube 35, during advancement through the outer catheter, the advancement force can be directly transmitted through the spine to the tip for improved pushability. Also, due to the linear connection, other peripheral portions of the support tube 35 can be maintained free of adjacent ribs or junctions to the tip to limit the effect on catheter deliverability due to increased friction with the outer catheter.

[0038] The catheter can also have a cover or membrane (not shown) disposed around at least a portion of the support tube 35 and the expandable tip 100 or enclosing them. Suitable membrane materials can include elastic polyurethanes such as Chronoprene which can have a Shore hardness of 40A or less, or silicone elastomers. A single or variable stiffness cover can be extrusion - formed or post - formed over the support tube 35 and the tip 100. The cover can also be laminated or heat - welded to the structure.

[0039] Alternatively, the cover can be formed of a series of polymer jackets. By disposing different jackets or sets of jackets at individual lengths along the axis 111 of the support tube 100, different pushability and flexibility characteristics can be imparted to different portions of the tubular part of the catheter. By configuring the jackets in an axial arrangement, it is possible to transition the overall stiffness of the catheter from a proximal end with higher stiffness to a distal end with very high flexibility. Alternatively, by making the polymer jackets of the cover a radial arrangement disposed around the support tube, the material properties can be adjusted across the thickness. In a further embodiment, by tapering or slotting the transition between jackets, a smoother transition between the flexibility profiles of adjacent jackets within the longitudinal arrangement can be provided.

[0040] In the example shown in FIGS. 3a - 3d, the expandable tip 100 of FIG. 1 can have a mouth support frame 110 of a strut comprising four distal hoops 118 and two support arms 116. The distal hoop 118 can have four proximal hoop troughs 121 and four distal peaks 119. The support arms 116 can contour the funnel shape of the tip 100, and when expanded and unconstrained, the diameter of the tip can be in the range of 1 mm to 10 mm, or more specifically 2.5 mm to 7.0 mm, for a device intended to treat occlusions at the ICA, carotid terminus, M1, and M2 locations. The support arms 116 also facilitate having a distal hoop 118 with four proximal hoop troughs 121 fully connected to the support arms, thereby eliminating the risk that the hoop troughs catch on the mouth of the outer catheter during retraction of the expanded mouth.

[0041] The support arms 116 can be V - shaped or Y - shaped struts extending from a support tube 35 that couple to two connections to a spine 42 or support tube at the proximal end 112 of the expandable tip 100 and four connections to the distal hoop 118. The V - shaped or Y - shaped support arms 116 can provide the frame 110 with the same support as a device having four or more support arms while reducing the number of connections to the support tube 35. By having two connections to the support tube 180 degrees apart, the support frame 110 can hinge about the connections when folded within the outer catheter while advancing through a tortuous vasculature, or can fully juxtapose the blood vessel wall using the hoop 118 when deployed within a curved blood vessel. The hinging action biases the bending along a plane extending radially through the two connections and the longitudinal axis 111 of the frame 110. The support frame 110 having two connections to the support tube 35 can have additional support arms extending from one connection, in which case it should be understood that a distal hoop 118 with more than four proximal troughs 121 is used.

[0042] The stiffness and changes in stiffness of the port support frame 110 are important in situations where significant distances and tortuosity can occur, such as when advancing from the patient's inner thigh through the aortic arch and into the neurovascular system within the skull. To further adjust the stiffness, the strut widths of the support arms 116 and the distal hoop 118 can be varied along the length of the struts by incorporating one or more constrictions 124. For example, a wider width at the peak of the V-shaped support arm 116 can provide greater radial force capabilities, while the narrowed central portion can help reduce lateral stiffness to aid in bending to follow a tortuous vascular structure. Having a greater width adjacent to the proximal trough 121 of the distal hoop 118 can also provide increased radial force. The constriction 124 at the distal hoop peak 119 can soften the distal end of the expandable tip 100 and improve the atraumatic properties of the tip. The constriction 124 can also help fold the hoop 118 back into the mouth of the outer catheter by reducing the force required to fold the distal peak 119 of the frame 110.

[0043] Referring to FIGS. 4a-4d, the support frame 110 can have an arrangement of four Y-shaped support arms 116 each having two support struts, and four distal hoops 118 having four hoop troughs 121 and four distal hoop peaks 119. The arrangement where each support arm 116 has two support struts allows for greater support of a cover or outer jacket, while limiting the number of distal peaks 119 to four can make the contour of the distal hoop 118 larger, rounder, and more atraumatic. As shown in FIG. 4a, by having four connections between the support tube 35 and the proximal end of the mouth framework 112 having the four support arms 116, when it is necessary to advance the tip 100 in an expanded configuration, greater axial stiffness can be provided to the joints than a tip having only two connections. The curvature of the support arms 116 also allows the frame 110 to expand and contract on both sides when folded within the outer catheter to improve followability through tortuous blood vessels.

[0044] Another support frame 110 can have, as shown in FIGS. 5a-5d, six Y-shaped support arms 116 and six hoops 118 with six distal peaks 119. It should be understood that the number of distal peaks 119 and support arms 116 used can vary from 1 to 50 or more. Configurations with an increased number of distal peaks 119, hoops 118, and / or support arms 116 can increase the support of the outer cover or jacket and increase the stiffness and radial force of the lateral frame. Similar to other examples, portions of the frame 110 can have variable-width struts to adjust the desired flexibility characteristics and bias bending at specific points on the frame.

[0045] FIGS. 6a-6d show another example of a support frame 110 of an expandable tip 100 that can have six hoops 118, six distal peaks 119, and six support arms. Two of the support arms can be Y-shaped support arms 152 having a connection to the support tube 35 at the proximal end 112 of the frame 110, while the other four arms can be V-shaped support arms 154 that can terminate at the proximal peaks 117 of their respective hoop support troughs 121. This design provides a frame 110 with closed-cell support hoops 118, improving the radial force capability of the tip 100, while having only two connections to the support tube 35. By having two connections to the support tube 35 that are 180 degrees apart, the frame can hinge about the support on a plane that extends radially through the Y-shaped support 152 and the longitudinal axis 111. This hinge can improve the tracking through the outer catheter and the wall conformity when the deployment position is a curved blood vessel.

[0046] The V-shaped support arm 154 provides additional surface area for supporting an outer cover or membrane (not shown). The outer membrane can reduce the possibility that the proximal peak 117 of the V-shaped arm 154 catches on a branched blood vessel or the mouth of an outer catheter during retraction. In another example, the proximal peak 117 of the arm 154 may be more rounded or U-shaped, similar to the distal peak 119 of the support hoop 118.

[0047] In another example, the mouth support framework 110 of the thrombectomy catheter can have six distal hoop peaks 119, two Y-shaped support arms 152, and four V-shaped support arms 154, as seen in FIGS. 7a-7d. The V-shaped support arm 154 can have a stitch 127 at its proximal peak 117 that is longitudinally aligned with the hem of the support tube 35. The arrangement of the link members 128 can extend between the stitches 127 and be connected to each stitch using knots, welding, or plastic deformation to form valves, loops, or enlarged abutting portions. Alternatively, the polymer member can utilize a thermoforming process to form the valves. The link members 128 can be string-like members, chain link members, rigid or semi-rigid members, or combinations thereof. Or, or in addition thereto, a radiopaque marker (not shown) can be disposed within the stitches 127 to assist in positioning the mouth 110.

[0048] Similar to other examples, this design can provide a closed cell structure to the distal hoop 118 to improve the radial force, while the stitches 127 and the link members 128 mean that there are only two rigid connections of the Y-shaped arms 152 to the support tube at the proximal end 112. By spacing the connection between the support tube 35 and the Y-shaped arm 152 at diametrically opposed positions of the tube, the frame 110 can hinge about the connection for following through the outer catheter and can better conform when the target position is in a curved blood vessel.

[0049] The arrangement of the link members 128 reduces the likelihood that the free proximal peak 117 of the V-shaped support arm 154 will catch on the mouth of the outer catheter when the expandable tip 100 retracts. The connection of the link members to the crimp 127 at the proximal peak 117 of the V-shaped arm 154 and to the crimp of the support tube is not rigid, and the members can move gently through the crimp 127 of these connections, whereby the support frame 110 can bend easily in tortuous blood vessels. If the link members 128 are made flexible, they will not contribute to the bending stiffness of the tip 100 in the folded state, but can snap taut when the distal support hoop 118 is expanded. The flexible members are strong enough to support the outer cover or membrane and can counteract the negative pressure forces applied to the cover during suction.

[0050] Another example of a mouth frame 110 may have a distal support hoop 118 with six peaks 119 around the perimeter of the mouth, as shown in FIGS. 8a-8d. The frame 110 can have three Y-shaped support arms 152 that connect adjacent hoop troughs 121 to the support tube 35. While similar in some respects to the previous example, the expandable tip 100 with three support arms will be more flexible in the folded delivery configuration than a tip with more arms. The fewer connections to the support tube can also help to fold the frame 110 back into a constrained state during retraction.

[0051] Figures 9a - 9d show another support frame 110 having four distal hoops 118 with four round distal peaks 119 and four hoop troughs 121. The struts of the distal hoops 118 can be tangentially aligned with four support arms 116 that extend from their respective hoop troughs 121 to the support tube 35. The support arms can have a circumferential undulation or sinusoidal pattern 130 along at least a portion of their length, where together with the support arms, a substantially conical contour of the support frame 110 is defined. The sinusoidal pattern 130 can be arranged such that when the tip 100 is in the folded configuration, the local peaks of adjacent support arms 116 do not overlap, but instead nest within each other, allowing the frame to be folded in a complementary manner. The amplitude of the waveform pattern 130 can be selected to be large enough to provide sufficient support to the polymeric cover or outer jacket, while not being so large that the support arms 116 need to be stretched longitudinally to fold neatly within the outer catheter. The waveform pattern 130 imparts flexibility to the frame 110, stretching and contracting in various directions when following a tortuous outer catheter within a blood vessel, or conforming to the blood vessel wall to achieve complete juxtaposition when deployed at a target location having a complex geometry.

[0052] To optimize lateral flexibility, when the frame is in a flat pattern or plan view, the support frame 110 can be configured such that the struts forming the waveform pattern 130 of the support arms 116 form an angle of 45 degrees to 135 degrees with respect to the longitudinal central axis 111. In this configuration, the more longitudinally oriented portions of the support arms 116 can bias bending about the struts extending between the peaks of the waveform pattern 130 when the frame is subjected to a torsional moment, and the support arms rely more on torsional flexibility than lateral flexibility. It should be understood that the angle formed by the struts of the pattern can be outside the range of 45 - 135 degrees if it is desired to obtain additional lateral flexibility instead of some torsional flexibility in bending.

[0053] In a similar example seen in FIGS. 10a - 10d, the support frame 110 can have a distal hoop 118 with four rounded distal peaks 119 and four support arms 116 with a sinusoidal pattern 130 extending from the hoop trough 121. Compared to the example of FIG. 9a, the support arms 116 can have additional local peaks within the wave pattern 130, thereby reducing the effective gap the frame has between adjacent support arms and providing additional support to a flexible outer membrane or cover. The additional undulations within the pattern also result in a longer strut length that can distribute torsional and lateral strain when the frame 110 is in a bent state while following through an outer catheter.

[0054] Another support frame 110 of an expandable tip 100 similar to FIGS. 10a - 10d is shown in FIGS. 11a - 11d. The frame can have four distal hoops 118 and four support arms 116 with a sinusoidal pattern 130 along at least a portion of their length. As described, the number and amplitude of the undulations of the wave pattern 130 can be adjusted to the desired flexibility characteristics of the frame 110. Additionally, the width of the struts can be adjusted to maintain flexibility while achieving the desired radial force.

[0055] Frame 110 can have additional strut(s) that function as one or more torsion members 132 extending between proximal hoop troughs 121 of support hoop 118. The torsion member 132 can extend circularly about the longitudinal central axis 111 of the device as shown, such that it can move distally under torsional load during retraction into the outer catheter, and this movement can assist the frame 110 in gripping a firm blood clot that in another situation might not fit completely into catheter lumen 44, resulting in secure gripping of the blood clot when the catheter is withdrawn through the vasculature. In another example, a portion of hoop peak 119 and / or torsion member 132 can have an axially rounded or curved profile, or the struts can intersect at an intermediate point and function as a hinge to reduce the transmission of torsional moment when the frame 110 is folded. This reduction in moment can be beneficial in a device where the outer cover or jacket is composed of a more rigid material with low elastic strain capacity and elongation at break, as it requires less movement of the cover as the frame is folded or collapsed within the outer catheter.

[0056] A further example of the support frame 110 having a distal hoop 118, four support arms 116, and four hoop peaks 119 is disclosed in FIGS. 12a - 12d. Each support arm 116 can branch between a hoop trough 121 and a more proximal support trough 126 to form an enlarged cell or opening 220. The enlarged opening within the arm 116 allows the arm to expand and contract on both sides about the longitudinal axis 111 of the frame, whereby the device can easily follow through an outer catheter within a tortuous vascular pathway. The branching of the struts of the support arm 116 allows the arm to rotate and bend more freely than if a single strut directly connected the hoop trough 121 to the support trough 126 without a cell. The junctions in the hoop trough 121 may also be axially longer than shown in FIG. 12c to better distribute transverse and torsional strains when the frame 110 needs to bend between the hoop peaks 119. Similarly, the enlarged openings may also have a smaller or larger spacing than shown to further encourage independent movement of the support arms 116 relative to each other.

[0057] The struts of the distal hoop 118 may also have a different width than the support arms 116. For example, if the struts of the hoop closer to the hoop peak 119 are wider or thicker, a support frame 110 with greater radial force capacity in the hoop and a more flexible support arm can be provided. If the struts closer to the peak 119 are narrower, the hoop can be made more flexible when sealing against the vessel wall.

[0058] Another support frame 110 having four bifurcated support arms 116 and four hoop peaks 119 is shown in FIGS. 13a - 13d. Compared with that of FIGS. 12a - 12d, this design can be characterized by a change in the shape of the hoop trough 121 connecting the joints, in which case, by direct connection, load can be transmitted more smoothly between the portion of the distal hoop 118 and the enlarged cell 220 of the support arm 116. The shape of the hoop trough 121 can also be changed to adjust the intersection angle of the bifurcated struts forming the distal hoop 118 and the support arm 116 in order to adjust the axial rigidity of the support frame 110.

[0059] FIGS. 14a - 14d show another variant of the orifice support framework 110 having four support arms 116 with enlarged cell openings 220 and both a proximal support hoop 134 and a distal support hoop 118. The distal support hoop 118 has four hoop peaks 119 and can be joined in the proximal direction by four respective hoop troughs 121. The arrangement of the connector struts 136 can connect the more distal hoop trough 121 and the proximal hoop trough 123 that functions as the joint between the struts of the proximal support hoop 134 and the struts of the support arm 116. An apparatus having multiple support hoops in an axial arrangement can exert a greater radial force to enhance juxtaposition and sealing in the target vessel. The seal provided by the expandable tip 100 allows for more effective suction by directing a complete suction force to the vascular portion distal to the tip, while maintaining a funnel-shaped contour to provide the blood clot with an inlet that converges in a gradually elongating manner, preventing shearing and fragmentation of the blood clot.

[0060] Various views of a design in which an expandable support frame 110 has an elongated connector strut 136 between a distal hoop 118 and a support arm 116 are shown in FIGS. 15a - 15d. The connector strut 136 can extend between the terminal end of the support arm 116 of the enlarged cell opening 220 and the strut of the distal hoop 118. The enlarged opening 220 within the arm 116 allows the tip 100 to expand and contract on both sides when operated within the outer catheter, while having a longer connector 136 provides greater lateral flexibility in bending, allowing the distal support hoop 118 to curve and flex relative to the support arm within a tortuous path. Further, the length of the connector strut 136 can be varied or can include curves or undulations to allow for different profiles of a cover or outer jacket, or to provide a more atraumatic contact surface with the vessel wall.

[0061] FIGS. 16a - 16d show a variant of another support frame 110 having a distal support hoop 118 and four support arms 116 with enlarged openings for flexibility. The struts of the support arms 116 can have a first strut width 114 along at least a portion of the length between the support trough 126 and the hoop trough 121, which is different from the second strut width 146 used for the support hoop 118. For example, the second strut width 146 of the hoop can be thinner, reducing the radial force exerted by the hoop and providing a more gentle contact with the vessel wall. The thinner hoop can also reduce the friction that occurs between the hoop 118 and the inner diameter of the outer catheter, allowing the tip to move forward and backward more easily through the outer catheter. Similarly, an increase in the thickness of the first strut width 114 in the support arm 116 can offset the decrease in the radial force of the support hoop 118 by adding rigidity when the tip 100 is expanded, resisting the negative pressure generated during suction and maintaining the expanded frame 110 in juxtaposition with the vessel wall. The arm 116 can also have closed cells or undulations to provide more surface area for supporting an outer cover or membrane.

[0062] Depending on the position of the occluding clot and the required pushability and flexibility of the support frame, other advantages can be obtained by varying the strut width of the support arms of the frame. A support frame 110 having four support arms 116 with enlarged closed cell openings and variable thickness struts can be seen in FIGS. 17a-17d. The struts of the support arms can include one or more constrictions 124 along the length between the proximal support trough 126 and the distal hoop trough 121. The constriction 124 can improve the lateral flexibility of the frame 110 when in a folded configuration for advancing through the outer catheter or when deployed in a curved blood vessel, such that the frame can bend while maintaining full apposition to the vessel wall. When the constriction 124 is located away from the support trough 126 and the hoop trough 121 and at the center of the strut of the support arm 116, the frame can maintain a high degree of flexibility along with support of the membrane.

[0063] When flexible characteristics are added to the support arms 116 of the tip framework 110, the radial force capability of the tip 100 can be maintained by making the support arm angle α with respect to the longitudinal axis 111 larger. The radial force can be adjusted to maintain proper sealing without causing vessel trauma. For example, when the tip framework 110 is heat set at an angle α of 30 degrees or more, a larger radially expanding force component can be applied.

[0064] Various views of a similar design of an expanded support frame 110 with a smaller tapered funnel shape and four support arms 116 with a reduced support arm angle θ are shown in FIGS. 18a-18d. The support arm angle θ can be, for example, about 30 degrees as opposed to about 45 degrees in FIGS. 17a-17d. The lower support arm angle can reduce the force required to advance the device through the outer catheter and, at the same time, can reduce the corresponding force required to retract the expanded frame 110 into the outer catheter during treatment. These forces can be further reduced by incorporating widened or constricted portions 124 into the arms 116 and / or the distal hoop 118.

[0065] Alternatively, the support arm angle θ may be in a range less than 45 degrees such that it is less likely to further expand when the catheter tip 100 is advanced distally within the outer sheath or within the blood vessel, but may be in a range greater than 10 degrees such that the mouth framework 110 of the catheter is maintained at a relatively short length. Optimizing the support arm angle θ can also help the tip 100 to seat against the distal tip of the outer catheter and the target vessel wall.

[0066] In the expanded state, at least a portion of the mouth framework 110 may taper distally from a larger maximum radial dimension to a smaller radial dimension. In this configuration, the outer axial profile of the tip body may also be generally rounded to provide a smooth contact surface with the vessel wall. A portion of the distal support hoop 118 may extend radially inward as shown in FIG. 18d to reduce the likelihood that the distal hoop peak 119 presses against the vessel wall, and the expanded tip can be advanced through the vessel over a short distance without causing vessel damage.

[0067] Figures 19a - 19c show another support frame 110 of the expandable tip 100 connected to the support tube 35 by four support arms 116. This frame 110 can also have a support arm angle θ smaller than that of the previously shown design. The portion of the distal support hoop 118 can extend radially inwardly between adjacent hoop troughs 121. The support arms 116 may be spaced 90 degrees apart in the clockwise position about the longitudinal axis 111 and may branch to form one or more closed cells, whereby the frame can expand and contract on both sides while navigating through the tortuous regions of the vascular structure. Additionally, the support arms 116 can include one or more wavy patterns or undulations 130 between the proximal end 112 and the distal end 114 of the tip, and this wavy pattern or undulation 130 includes, as shown, segments adjacent to portions of the closed cells or the more proximal support troughs 126 and the more distal hoop troughs 121. The undulations 130 combined with the constrictions 124 can improve the lateral flexibility of the support frame.

[0068] The support arms 116 can be connected to the support tube 35 of the catheter at the proximal end 112 of the mouth frame 110. One or more spines 42 of the support tube may be aligned with one or more of the support arms, and longitudinal forces can be smoothly transmitted between the spine and the frame. The support arms 116 that are not aligned with the spines 42 can be connected to the aligned support arms or can terminate at a point near the distal end of the support tube 35. In such a configuration, the compressive forces generated during thrombus retrieval may not cause unnecessary expansion of the support tube 35 or the mouth frame 110 during the procedure.

[0069] Any of the mouth support frames 110 disclosed herein can be sealed or encapsulated by an elastomeric membrane cover 50. Although many of the previous figures do not show the cover for clarity, Figure 20 shows how the membrane 50 can cover at least a portion or all of the struts of the mouth framework 110 of the expandable tip 100 and at least a portion of the circumferential ribs 43 and the axial spines 42 of the support tube 35.

[0070] The thickness of the membrane cover 50 may be maintained between and on the struts of the mouth support frame 110, or the thickness may vary along the frame 110. In one embodiment, the cover 50 may be applied such that the membrane thickness between the struts is close to the ligament thickness of the membrane above and below the struts. In another embodiment, the cover may have a uniform wall thickness, and the thickness between the struts is greater than the ligament thickness remaining above and below the struts. The membrane cover 50 may also include geometric features and / or thinning regions appropriately arranged to vary the contribution of the membrane to the rigidity of the combined support frame 110 and cover from the membrane.

[0071] The membrane cover 50 may be stitched to the support tube 35 and the struts of the mouth frame 110, or may be reflowed onto and between the struts (using inner and outer layers such that it is flush with the inner surface of the support strut or the strut has membrane material above the outer surface and below the inner surface of the support strut), heat shrunk to bond to the outer surface of the support strut, or welded in place within a defined zone 52. The cover 50 may also be formed by an immersion process (using inner and outer layers such that it is flush with the inner surface of the support strut or the strut has membrane material above the outer surface and below the inner surface of the support strut). As seen in the profile examples of FIGS. 21a - 21c, the method of fitting the cover 50 to the distal end 114 of the mouth frame work 110 can also vary. The membrane cover 50 may be finished flat (FIG. 21a), or the cover may be trimmed to follow the contour of the struts of the support frame 110 and heat welded within a zone 52 along the outer perimeter of the distal hoop 118 (FIG. 21b). Heat can be used to locally reflow and / or bond the membrane to the support strut, and at least bond within the region of the hoop peak 119 of the distal hoop 118. In another example of FIG. 21c, the cover 50 is sufficiently loose or slack so as to be folded radially inwards (or outwards) to a position proximal to the distal end 114 of the mouth frame work hoop strut 118 and can be heat welded or otherwise bonded between the inner and outer layers. The membrane can extend completely within the frame such that the frame struts are not exposed.

[0072] As shown in FIG. 22, the membrane cover 50 may have a structure with good ductility and a high elastic strain limit so that it can be easily expanded by the minimum radial force from the underlying support frame 110. Alternatively, when the frame is in the expanded form and the cover 50 is formed using an elastomeric material or a non-flexible material, the cover can be properly wrapped when folded for delivery and can cover again when expanded for use. The membrane cover 50 may be formed with a circular opening and, as shown, may include ribs 54 of a soft elastomer or gel (formed by a reflow, dipping, or molding process) to provide non-invasive contact with the blood vessel wall. The cover of the orifice support frame 110 may also have flow-inducing features such as a plurality of flexible fins, vanes, or recesses disposed around the outer and / or inner periphery in a configuration with vortices or laminar flow. Such features can be included in a molding or forming mandrel.

[0073] The outer surface of the expandable tip and / or the membrane or outer jacket can be coated with a low-friction or lubricious hydrophilic material, or a low-friction material such as a fluoropolymer like PTFE or FEP so that the thrombectomy catheter can be smoothly delivered through the outer catheter and the auxiliary device can be smoothly delivered through the lumen of the thrombectomy catheter. In addition, the inner surface of the struts of the expandable tip or, if enclosing the tip, the inner surface of the membrane cover can be coated with a liner or otherwise manufactured to have low-friction properties.

[0074] In many examples, the support tube 35 can also share an outer and / or inner lubricious film or coating with the tip 100. The coating can be delivered via dipping, spraying, plasma, profiled mandrel, or any other commonly used technique. Alternatively, the membrane cover or jacket can be impregnated with particles having low-friction properties.

[0075] In another embodiment, the mouth framework 110 may include an electrospun or other porous cover that can reduce the flow of blood from the proximal side of the tip-vessel wall seal. A 50% to 99%, more preferably 60% to 80%, reduction in flow still allows a small recirculation flow portion from the proximal side while directing most of the suction flow to the blood clot. This flow can help reduce the likelihood of vessel collapse under excessive suction where the vessel is poorly supported by the surrounding tissue or where there is no lateral branch between the occluded vessel and the expanded tip 100 and a mechanical thrombectomy device or stent retrieval device cannot open a portion of the occluded vessel.

[0076] Examples of other mouth support frames can have longitudinal supports that are independent of each other in the distal direction, whereby the longitudinal supports can bend individually. FIGS. 23a-23d show an example having a support frame 210 with a plurality of interconnected struts formed in unconnected petals 215 where the expandable tip 200 is disposed about the longitudinal axis 111 of the device. The petals 215 can have a distal hoop member 218 that joins one or more longitudinal arms 216, and the petals can be sized and shaped such that there is no overlap between them. Alternatively, the petals 215 may be formed in an oversize shape such that they can overlap each other when held in the desired expanded shape by a membrane cover. Overlapping petals help increase the radial force capacity of the frame while being able to slide relative to each other to share and distribute strain during the procedure.

[0077] Similar to other disclosed unconstrained embodiments, the petals 215 can expand radially so that a substantially conical surface is formed by the combination of the arms 216 around the longitudinal axis 111. The struts of the longitudinal arms 216 can branch to form one or more undulations or closed cells 220, whereby the petals 215 can expand and contract independently of the forces received when the tip 200 is deployed and expanded at the target site during navigation through the outer catheter or during a thrombus removal procedure. By having longitudinal arms 216 aligned closely with the longitudinal axis 111 of the tip 200, good column rigidity and pushing-in characteristics can be maintained. The petals 215 can also include other members to improve the radial force generated and further support the membrane cover during suction.

[0078] The support frame 210 can also have a proximal support hoop 230 that extends distally from the support trough 126, and the support trough 126 forms a connection with a support tube of a catheter (not shown for clarity). The connection strut 236 can form the distal end peak of the proximal support hoop 230 and connect the hoop to the longitudinal arms 216 of the frame.

[0079] Figures 24a - 24d have various views of an alternative support frame 210 for a catheter having distally unconnected petals 215. The struts of the proximal support hoop 230, the longitudinal arms 216, and the distal hoop member 218 can have variable or tapered thicknesses between the proximal end 112 and the distal end 114 of the support frame 210. The struts of the support hoop 230 can be thicker, for example, than the struts of the connection strut 236, and then the struts of the connection strut 236 can have a greater thickness than the struts of the longitudinal arms 216 that form the closed cells 220. Similar to local constrictions in other examples, the strut width of this orifice frame 210 tapering gradually distally maintains the radial force capability while keeping the individual petals 215 flexible, thereby allowing them to react independently to lateral loads.

[0080] In a similar variant, FIGS. 25a - 25d show various orientations of the support frame 210 for the expandable tip 200 having eight proximal support hoops 230 that connect four distal unconnected flaps 215. In FIG. 25b, the support troughs 126 that form the proximal end portions of the support hoops can have alternating axial spacing, and the intersection of the struts on the proximal and distal sides of the connectors 236 and the closed cells 220 occurs at different angles than in FIG. 24c, allowing for a more uniform and balanced strut spacing throughout the frame 210.

[0081] Alternatively, the orifice support frame 210 having distal unconnected flaps 215 can have a direct connection to the support tube and a direct connection to either a common axial strut or the most distal rib or lip (not shown). FIGS. 26a - 26d show a support frame with a direct connection portion having eight longitudinal arms 216 that join four distal hoop members 216 to form the four unconnected flaps 215. In this example, the direct connection of the longitudinal arms 216 at the proximal end 112 of the frame 210 can replace or complement the proximal support hoops 230 formed in other designs. The direct connection allows the individual flaps to bend and curve more freely relative to each other and about the support frame when the catheter faces a tortuous forward path.

[0082] The longitudinal arms 216 can include one or more closed cells 220 to maintain the necessary radial forces while providing additional support for the membrane cover. The spacing between the direct proximal connection and the closed cells can overlap or not overlap with each other when the flaps are held in the desired radial shape of the frame by the cover and can be such that they can collapse properly when the tip is folded into the outer catheter.

[0083] Figures 27a - 27d show an alternative expandable tip 200 in which the mouth frame 210 has six distally unconnected petals 215 and six longitudinal arms 216 each extending from a direct connection to a support tube (not shown) at the proximal end 112. Each longitudinal arm 216 can include one or more closed cells 220 that end at a generally rounded hoop member 218 at the distal end 114. A portion of the hoop member 218 of the petal 215 can take on a diameter that is slightly smaller than the maximum expansion diameter of the contour of the tip 200 by curving radially inward. This curvature can reduce the likelihood that the distal hoop member 218 will push against the blood vessel wall and, without causing blood vessel damage, can easily advance the expanded tip through the blood vessel as needed.

[0084] The support frame 210 can also have six longitudinal arms 216 each extending from a direct connection at the proximal end 112 and can form six distally unconnected petals 215, as shown in Figures 28a - 28d. When unrestrained, the petals 215 expand radially, such that the contour of the combination of arms 216 around the longitudinal axis 111 can be substantially conical. One or more of the longitudinal arms 216 can have circumferential undulations 130 or waveforms along at least a portion of their contours. The undulations 130 give the arms a contour that provides more support areas for the membrane cover while improving the lateral flexibility of the frame 210. The support areas of the cover can be further improved by increasing the magnitude of the undulations, decreasing the period of the amplitude, or both. The undulations 130 can also be staggered or otherwise configured to nest within each other and fold in a complementary manner when the frame is in its folded configuration. Additionally, the longitudinal arms 216 may be capped at the distal end by a hoop member 218 to form loops or closed cells 220. The most distal ends of the closed cells 220 of the arm 216 taper inward from the maximum expansion diameter of the frame, as shown in Figures 28b and 28d, and can give the frame 210 a more atraumatic contour.

[0085] As can be observed from FIGS. 29a - 29c, an alternative expandable oral support frame 210 can have five unconnected petals 215 equally spaced around the longitudinal axis 111. The longitudinal arms 216 that make up each petal can be independently connected to the support tube. The struts of the longitudinal arms 216 may have a first thickness different from a second thickness of the struts in the more distal region of the arm, near the proximal end 112, in order to combine good pushability and distal flexibility. As with other examples, the arms 216 may have undulations 130 that allow the arms to curve and bend independently about their own axes, and may have distal closed cells 220 that provide greater support by the membrane cover.

[0086] It should be understood that the unconnected petals 215 of FIGS. 29a - 29c are fewer compared to six or more in the designs of other examples, but can provide a non - traumatic curve to the tip of the mouth and increased bending flexibility for a given strut thickness and width. To maintain proper support of the membrane cover, designs with fewer petals can incorporate additional undulations 130 and / or closed cells 220 to adequately provide the appropriate radial force and prevent the cover from collapsing under the suction force during the procedure.

[0087] Some views of the support frame 210 having a plurality of undulations or corrugations 130 along the length of the longitudinal arms 216 and an array of closed cells 220 around the longitudinal axis 111 at the distal end 114 are considered in FIGS. 30a - 30d. The undulations 130 may be circumferential and have a smooth periodic amplitude, or the arms and amplitude may be helically twisted with respect to the axis 111. Adding undulation length to the arms 216 allows each petal 215 to rotate and bend better about the longitudinal axis of the arm independently of the other petals, providing a device that can more easily follow through the outer catheter when the frame is in a folded state. The helical twist within the arms 216 can further assist the petals 215 in rotating through the tortuous anatomical structure of the blood vessel.

[0088] In another alternative configuration, the expandable distal end portion 300 of the catheter can have a radial arrangement of struts or strands configured in a closed cell mesh 310, as shown in FIGS. 31a - 31b. The mesh has a proximal end 112 and a distal end 114 and can form a substantially conical or funnel - like shape around the longitudinal axis 111 when expanded without being constrained upon exiting the outer catheter. The mesh arrangement can be made from wire or cut from a shape - memory alloy, whereby the mouth can be heat - set to self - expand from a folded delivery configuration to an expanded deployment configuration. The mesh 310 can be adhered or otherwise connected to the support tube 35 of the catheter at the proximal end 112. The mesh pattern 310 may be manufactured to have a single circumferential junction for attaching the proximal end, or if the support tube 35 has a structure of ribs 43 and spines 42, the individual strands of the mesh may be coupled to the most distal rib of the tube. A flexible polymer membrane 50 (such as that seen in FIG. 22) can cover some or all of the closed cell mesh 310 of the catheter tip 300.

[0089] In another example, the support tube 35 can have a metal and / or polymer strand structure formed in a patterned mesh or coiled structure. The structure can form a radial arrangement as a continuous tubular catheter body and may in some cases be integral with the further expandable tip 300. In this case, the change in rigidity between the support tube 35 and the tip 300 is kept near a single support and minimized to better distribute strain. The tube can be coated or encapsulated with a cover or membrane to provide a smooth surface for tracking within the outer catheter and for internal passage of auxiliary devices.

[0090] Figure 31b shows a close-up view showing a possible repeating pattern of the closed cell mesh 310 of the expandable tip 300. When cut from a flat pattern, the radial profile of the formed mesh pattern 310 can be linear as shown and can have a constant angle with respect to the longitudinal axis 111. In other examples, the profile may be a more widely spread concave arc to form a more non-invasive rounded outer surface for contacting the vessel wall.

[0091] The closed cell mesh array 310 that makes up the mouth framework may be a continuous polygonal pattern such as triangular or quadrilateral cells connected by sharing the vertices of adjacent cells. In one example, the array 310 can have an elongated quadrilateral pattern forming individual closed cells, as seen in Figure 31b, where the local array peak 312 indicates the shared vertex. The pattern can repeat axially and radially, and the most distal array peaks 312 of adjacent cells may be joined by a curved distal hoop 314 or crown to indicate the outer perimeter of the expandable mouth. Similarly, the peaks of the distal hoops may be joined together by a single circumferential hoop or crown to prevent individual distal hoops from snagging or catching on branch vessels or similar features.

[0092] The cells formed by the shared array peaks 312 define the open holes 316 of the closed cell mesh 310 structure. The holes 316 of the mesh can be sized to adjust the filtering characteristics of the expandable tip 300. For example, large holes provide improved flexibility at the tip, resulting in delivery advantages, but an outer membrane cover or jacket (not shown) may be incorporated to block or restrict blood flow from the proximal region of the tip when deployed in an expanded form at the target site.

[0093] Alternatively, the holes 316 may be of a micro size and form a mesh array 310 that is dense enough to impede flow even without an outer jacket or membrane cover. In this case, the outer cover of the support tube 35 can terminate near or within a region immediately distal to the proximal end 112 of the expandable tip 300, at which position the diameter of the tip begins to expand into the deployed configuration. By not requiring an outer membrane cover, the expandable tip 300 can more easily follow through the outer catheter and the required forward force can be limited. As a result, although still applicable, a lubricity or low friction coating may not be required.

[0094] There are a variety of minimally invasive stent patterns, meshes, or screens found in a wide range of performance and applications in commercially available products. The closed cell mesh 310 of the expandable tip 300 can utilize any expandable stent pattern known in the art of stent patents and products, and it should be understood that the size of the holes 316 need not be limited to those disclosed herein.

[0095] The present invention is not necessarily limited to the described examples, which may vary in composition and detail. The terms "distal" and "proximal" are used throughout the foregoing description and are meant to refer to the position and direction with respect to the treating physician. Thus, "distal" or "distally" refers to a position away from or a direction away from the physician. Similarly, "proximal" or "proximally" refers to a position near or a direction toward the physician. Further, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0096] As used herein, the term "about" or "approximately" with respect to any numerical value or range of numerical values indicates a tolerance of a suitable dimension that enables a component part or a set of components to function in accordance with its intended purpose as described herein. More specifically, "about" or "approximately" can refer to a range of values of ±20% of the recited value. For example, "about 90%" can refer to a range of values from 71% to 99%.

[0097] In describing exemplary embodiments, technical terms are used for clarity. Each term is intended to have its broadest meaning as understood by those skilled in the art and is intended to include all technical equivalents that operate in a similar manner to achieve similar purposes without departing from the scope and spirit of the present disclosure. Similarly, it should be understood that references to one or more components in a device or system do not exclude the presence of additional components or components intervening between those explicitly identified. References to one or more steps of a method do not exclude the presence of additional method steps or method steps intervening between those explicitly identified. For the sake of clarity and brevity, not all possible combinations are listed, and such modifications are often obvious to those skilled in the art and are intended to be within the scope of the following claims.

[0098] 〔Embodiments〕 (1) An expandable mouth for a thrombectomy catheter, the expandable mouth having a proximal end, a distal end, a longitudinal axis, a self-expanding mouth framework comprising a plurality of interconnected struts, a folded delivery configuration, an expanded deployment configuration, and a polymeric membrane cover, wherein the struts of the mouth framework extend longitudinally between the proximal end and the distal end and form a substantially conical surface about the longitudinal axis in the deployment configuration, one or more support arms An expandable mouth, comprising: a self-expanding mouth framework including one or more distal hoops that form the outer periphery of the mouth opening of the thrombus retrieval catheter. (2) The expandable mouth according to embodiment 1, further comprising a support tube connected proximally to the mouth framework, the support tube comprising a plurality of ribs and one or more axial spines. (3) The expandable mouth according to embodiment 1, wherein the mouth framework further comprises one or more constrictions. (4) The expandable mouth according to embodiment 2, wherein at least one axial spine of the support tube is axially aligned with a support arm. (5) In the deployed state, the mouth framework is tapered such that the proximal portion of the mouth framework has a first radial dimension and the distal portion of the mouth framework has a second radial dimension that is greater than the first maximum radial dimension. The expandable mouth according to embodiment 1.

[0099] (6) The expandable mouth according to embodiment 5, wherein the second maximum radial dimension is at least 2.5 mm in diameter and is sized to be larger than the inner diameter of the target blood vessel. (7) The expandable mouth according to embodiment 1, wherein at least a portion of the distal hoop extends radially inward in the distal direction from the maximum radial dimension of the mouth framework. (8) The expandable mouth according to embodiment 1, wherein at least a portion of the strut of the support arm has a width different from at least a portion of the width of the strut of the distal hoop. (9) The expandable mouth according to embodiment 1, wherein at least one strut of the one or more support arms terminates in a support trough and a hoop trough to form a closed cell. (10) The expandable mouth according to embodiment 1, wherein the one or more support arms include at least one circumferential undulation.

[0100] (11) The at least one strut of the one or more support arms terminates at the support tube and the hoop trough to form a closed cell, the expandable port according to embodiment 2. (12) Further including an angle formed between the support arm and the longitudinal axis, the angle having a range of about 10 degrees to about 45 degrees, the expandable port according to embodiment 1. (13) Further including an angle formed between the support arm and the longitudinal axis that is about 30 degrees, the expandable port according to embodiment 1. (14) An expandable port for a thrombus retrieval catheter, the expandable port being a longitudinal axis and a self-expanding port framework comprising a plurality of interconnected struts, the port framework having a folded delivery configuration and an expanded deployment configuration, the plurality of interconnected struts configured as one or more distally unconnected petals disposed about the longitudinal axis, each of the one or more distally unconnected petals configured to bend independently, the petals connecting one or more longitudinal arms and comprising one or more distal hoop members formed from the struts of the port framework, a self-expanding port framework; and a polymer membrane coating at least a portion of the port framework. An expandable port. (15) Each strut of the one or more longitudinal arms of the distally unconnected petals includes at least one circumferential undulation, the expandable port according to embodiment 14.

[0101] (16) Each strut of the one or more distally unconnected petals forms at least one closed cell, the expandable port according to embodiment 14. (17) An expandable port forming a distal end of a suction catheter, the expandable port being a proximal end and a distal end and A radial strand array forming a closed cell mesh disposed about a longitudinal axis extending from the proximal end to the distal end, the closed cell mesh being self-expandable from a folded delivery configuration to an expanded deployment configuration, the expanded deployment configuration forming a substantially conical surface about the longitudinal axis, the strands of the closed cell mesh including a local array peak and a fully connected stent pattern of enclosed holes, adjacent array peaks at the distal end of the expandable mouth being connected by a distal hoop, a radial strand array, comprising an expandable mouth. (18) The expandable mouth according to embodiment 17, wherein the holes of the closed cell mesh are sized to impede blood flow. (19) The expandable mouth according to embodiment 17, wherein at least a portion of the closed cell mesh is covered with a polymer membrane cover. (20) The expandable mouth according to embodiment 17, wherein at least a portion of the closed cell mesh is coated with a low friction coating.

Claims

1. 1. An expandable port for a thrombectomy catheter, the expandable port comprising: A proximal end; A distal end. A longitudinal axis; a self-expanding mouth framework comprising a plurality of interconnected struts; a polymeric membrane cover supported by at least a portion of the self-expanding ostomy framework; the self-expanding ostial framework having a collapsed delivery configuration and an expanded deployed configuration; the plurality of interconnected struts of the self-expanding ostial framework comprising a plurality of support arms and a plurality of distal curved portions; In the deployed configuration, the self-expanding ostial framework is tapered such that a proximal portion of the self-expanding ostial framework has a first radial dimension and a distal portion of the self-expanding ostial framework has a second radial dimension that is greater than the first radial dimension; The plurality of distal curved portions form an expandable port opening of the thrombectomy catheter.

2. The expandable port of claim 1 , wherein in the deployed configuration, each of the plurality of distal curved portions has an inverted U-shape or a semicircular shape.

3. each of the plurality of distal curved portions has a rounded distal peak extending in a distal direction; The expandable port of claim 2 , wherein proximal ends of the plurality of distal curved portions are connected to distal ends of the plurality of support arms.

4. The expandable port of any one of claims 1 to 3, wherein the port opening of the thrombus retrieval catheter formed by the plurality of distal curves is circular in a plane perpendicular to the longitudinal axis.

5. a support tube proximally connected to the self-expanding ostium framework; The expandable port of any one of claims 1 to 4, wherein a proximal end of at least one of the plurality of support arms is connected to a distal end of the support tube.

6. The expandable ostium of any one of claims 1 to 5, wherein in the deployed configuration, the self-expanding ostium framework has a funnel shape.

7. a support tube proximally connected to the self-expanding ostium framework; 2. The expandable port of claim 1, wherein in the deployed configuration, at least one of the plurality of support arms has a Y-shape, two distal ends of the at least one of the plurality of support arms of the Y-shape are connected to two proximal ends of one of the plurality of distal curved portions, and the proximal end of the at least one of the plurality of support arms of the Y-shape is connected to a distal end of the support tube.

8. 8. The expandable port of claim 7, wherein in the deployed configuration, a support arm other than the at least one of the plurality of support arms has a V-shape, two distal ends of the V-shaped support arm are connected to two proximal ends of a distal curved portion of any one of the plurality of distal curved portions, and a proximal end of the V-shaped support arm is not connected to the support tube.

9. The expandable ostium of claim 1 , further comprising a support tube connected proximally to the self-expanding ostium framework, the support tube comprising a plurality of ribs and one or more axial spines.

10. The expandable port of claim 9 , wherein at least one of said one or more axial spines of said support tube is axially aligned with at least one of said plurality of support arms.

11. The expandable port of claim 1 , wherein the second radial dimension is at least 2.5 mm in diameter and sized larger than an inner diameter of a target vessel.

12. The expandable port of claim 7, wherein the plurality of support arms consist of two support arms, and in the deployed configuration, each of the two support arms has the Y-shape, and the proximal ends of the two support arms of the Y-shape are connected to the distal end of the support tube 180° apart in the circumferential direction of the support tube.

13. The expandable port of any one of claims 1 to 12, wherein in the deployed configuration, a closed space is formed by one of the plurality of support arms having a V-shape or a Y-shape and one of the plurality of distal curved portions.

14. The expandable port of any one of claims 1 to 13, wherein in the deployed configuration, at least one of the plurality of support arms has a wavy shape.

15. a support tube proximally connected to the self-expanding ostium framework; and a string member.

2. The expandable port of claim 1, wherein in the deployed configuration, at least one of the plurality of support arms has a V-shape, two distal ends of the at least one of the plurality of V-shaped support arms are connected to two proximal ends of one of the plurality of distal curved portions, and the proximal end of the at least one of the plurality of V-shaped support arms is connected to one end of the string-like member, the other end of the string-like member being connected to the support tube.

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