Clot retrieval system for removing occlusive clots from blood vessels

Abstract

The present invention provides a clot capture catheter, which includes an elongated tubular shaft having a proximal end, a distal end, and an inflatable expandable member at the distal end. The expandable member is capable of being inflated from a collapsed delivery configuration to an expanded configuration. In the expanded configuration, the expandable member expands to define a funnel shape having an enlarged distal clot entry tube head at the distal-most end of the catheter. In the expanded configuration, the expandable member may extend distally beyond the distal-most end of the shaft. The expandable member may be integral with the distal end of the catheter shaft.

Description

Technical Field

[0001] The present invention relates to a device intended for use in an operation involving the removal of acute blockages from a blood vessel. Acute blockages may include clots, displaced devices, migrating devices, large emboli, and the like. Thromboembolism occurs when part or all of a thrombus detaches from the vessel wall. The clot (now referred to as an embolism) is then transported in the direction of blood flow. If the clot is lodged in the cerebral vasculature, an ischemic stroke may result. If the clot originates from the venous system or the right side of the heart and is lodged in the pulmonary artery or its branches, a pulmonary embolism may result. The clot may also not be released in the form of an embolism, but may form locally and block the vessel, a mechanism common in the formation of coronary artery blockages. The present invention is particularly useful in cases involving the following situations: removing clots from cerebral arteries of patients with acute ischemic stroke (AIS), coronary native or transplanted vessels of patients with myocardial infarction (MI), and pulmonary arteries of patients with pulmonary embolism (PE), as well as other peripheral arterial and venous vessels occluded by clots. Background Art

[0002] Recent clinical studies have shown that mechanical thrombectomy is a very effective method for restoring blood flow to ischemic tissue in patients who have recently suffered an acute ischemic stroke. The procedure typically involves advancing a thrombectomy device (which may be a stent retriever and / or a suction catheter) to the occluded clot, engaging the clot and retracting the clot into a local suction catheter or into a safe position in a more proximal guide or sheath. In the latter case, a balloon-guided catheter is typically employed, and when such a catheter is used, the balloon can be inflated to restrict the flow through the catheter to more easily and safely retrieve the captured clot into the catheter tip. Aspiration through a balloon-guided catheter is typically used to reverse flow in the distal vasculature, assisting in transferring the captured clot into the catheter tip.

[0003] However, despite the benefits provided by balloon guides, currently available devices suffer from significant limitations:

[0004] One of these limitations is due to the location of the balloon on the catheter. Conventional balloon guide catheters have a "dead space" distal to the balloon due to the way the distal neck of the balloon is attached to the catheter shaft and the presence of the distal catheter tip. This dead space is an area where clots cannot be easily aspirated or aspirated, so if clot fragments become lodged in this area, they can escape distally when the balloon is deflated (which must be performed before the catheter is removed from the patient), potentially causing a blood vessel obstruction and serious harm to the patient.

[0005] A second limitation of conventional balloon guide catheters is the level of shear stress induced in the clot when the clot is withdrawn into the catheter. This stress is affected by multiple factors, including the relative size of the clot and the catheter lumen and the friction coefficient of the clot relative to the catheter. The clot entering the catheter must suddenly change shape to conform to the inner diameter of the catheter in order to enter the catheter. This sudden change can produce high shear stress at the contact surface between the clot and the catheter end, which can shear or tear the clot, release clot fragments, which can then be suspended in the aforementioned dead space, or most or all of the clot can be removed from the stent retractor or aspiration catheter that has been withdrawn into the balloon guide catheter. If these clot portions or fragments are not then completely aspirated into the balloon guide catheter, they can move distally and cause damage or death. Summary of the invention

[0006] The present invention solves the problems of clot shearing and clot fragments stuck in "dead space" at the distal tip of previously described balloon guide catheters.The subject of the present invention is a catheter configured for use in a mechanical thrombectomy procedure comprising an elongated tubular shaft having an expandable distal tip portion.

[0007] The elongated shaft includes a first lumen through which other catheters or components can pass and through which clots can be aspirated, and a second lumen within the shaft wall extending from the proximal hub of the catheter to the inflatable member at the distal end of the shaft. The second lumen can be circular in cross-section, or can be oblong, and can include multiple lumens.

[0008] One embodiment of the expandable distal tip portion includes a funnel-shaped balloon and has a collapsed state and an expanded state. In the collapsed state, the balloon is deflated and may be pleated and / or pleated to minimize its profile for advancement through the introducer sheath and through the patient's vasculature. In the expanded state, the balloon is inflated. Balloon inflation serves multiple purposes:

[0009] 1) The balloon can be inflated to a diameter that causes it to contact the vessel wall, thereby partially or completely blocking blood flow past the balloon. This in turn can help reduce the likelihood that part or all of the clot will be retrieved into the catheter during the thrombectomy procedure. This also facilitates effective suction through the catheter, ensuring that the suction produces reverse flow in the distal vessel.

[0010] 2) Balloon inflation can help stabilize the catheter within the vessel, preventing accidental migration of the catheter and subsequent vascular trauma.

[0011] 3) The inflation of the balloon of the present invention also changes the shape of the catheter tip, optimizing the geometry of the interface between the catheter tip and any material or device drawn into it. Specifically, this shape change reduces the shear forces exerted on the thrombotic material as it is drawn into the catheter, and minimizes or eliminates any "dead space" or grooves that may trap thrombi.

[0012] In one embodiment of the invention, the funnel-shaped balloon is integral with the distal catheter tip portion and is formed from a length of polymer tubing that is inverted so that the distal junction between the balloon and the catheter is located below (and inside) the balloon itself.

[0013] The balloon wall thickness can be profiled / tapered to force the balloon to preferentially expand more in certain areas than in other areas, thereby enabling a funnel-shaped cross-section when inflated. In one embodiment, the wall thickness of the proximal and distal portions of the balloon is greater than the wall thickness of the middle section. In another embodiment, the wall thickness of the proximal portion of the balloon is greater than the wall thickness of the middle and distal sections.

[0014] In another embodiment, the proximal portion of the balloon is reinforced to limit its expansion when inflated, so that the distal portion of the balloon preferentially expands and forms a bulbous funnel shape at the distal end. The reinforcement can be in the form of ribs that can extend axially or radially along the balloon and / or can be formed of the same or different material as the balloon itself.

[0015] The inverted balloon can be positioned so that it hangs over the catheter tip, in which case the balloon material is not subject to any axial tension in the unexpanded state, unlike most conventional flexible balloons. This lack of axial tension coupled with the overhang (ideally greater than 0.5 mm but less than 3.5 mm) is key to ensuring that the balloon can be inflated into a funnel-like shape.

[0016] Prior to assembly onto the catheter shaft, the balloon may be pre-formed into a funnel-like shape, in which case it may be advantageous to also provide corrugations or preferably pleats thereon to facilitate efficient rolling down into a low profile.

[0017] In one series of embodiments, multiple balloons are used on the catheter shaft. This has the advantage of allowing individual balloon properties to be customized for specific tasks. For example, a low-pressure flexible balloon can be designed to seal against the vessel wall to help form a flow block, while another balloon can be designed to adopt a funnel-like shape at the distal catheter tip to minimize shear forces on the clot and facilitate easy entry of large and / or firm clots into the catheter tip. In some cases, a higher pressure, less flexible balloon can be used to help prevent the catheter tip from getting too close to the vessel wall and hindering clot retrieval.

[0018] The material used in the catheter construction must be carefully selected. For high-pressure balloons, relatively high modulus materials such as PET or polyamide are good choices, but for some inflatable parts of the catheter of the present invention, softer, more flexible materials are needed. This preferably includes an amorphous elastomeric polymer so that it can be stretched / strained to at least twice and up to 5 times its uninflated diameter under inflation pressure, and recovers most or all of its unexpanded shape when deflated. This requires the material to withstand at least 200% and ideally 500% or more elastic strain, with minimal plastic deformation. The cross-linking of polymer chains greatly facilitates such high-level recoverable strains, so thermosetting materials such as silicone rubber may be a good choice for flexible balloons. However, silicone is not a material that is easily joined to a second material, because it is not easy to melt and is not easy to miscible with another material to form, for example, a strong and low-profile welded joint. For this reason, polyurethane elastomers are preferred materials for balloons of the present invention. In particular, thermoplastic polyurethane elastomers would be ideal materials because they can be melted as part of a welding or joining process, or can be solvent bonded or adhesively bonded. In addition, such polyurethanes can be bonded to a compatible family of materials to form a stiffness gradient along the length of the catheter that is greater than that possible when limited to polyurethane. For example, a very soft polyurethane can be used for the balloon and very distal section of the catheter; one or more Pebax (polyether block amide copolymer) materials can be used for the middle section of the catheter; and a polyamide material can be used for the proximal section of the catheter shaft. This family of materials offers increasingly higher hardness and Young's modulus (or stiffness), allowing a very flexible distal shaft region to smoothly transition to a stiffer proximal shaft region. Polyether block amide materials have the advantage of being bondable to both polyurethanes and polyamides, although polyurethanes and polyamides do not readily bond to each other.

[0019] In one aspect, the present invention provides a clot capture catheter comprising an elongated tubular shaft having a proximal end, a distal end, and an inflatable expandable member at the distal end, the expandable member being capable of being inflated from a collapsed delivery structure to an expanded structure, wherein in the expanded structure the expandable member extends to at least the distal-most end of the shaft and extends radially outward from the shaft at the distal-most end of the shaft to define a tube head.

[0020] In one aspect, the present invention provides a clot capture catheter comprising an elongated tubular shaft having a proximal end, a distal end, and an inflatable expandable member at the distal end, the expandable member being capable of being inflated from a collapsed delivery configuration to an expanded configuration, wherein in the expanded configuration the expandable member extends radially outward at the distal-most end of the catheter to define a funnel-shaped cross-section having an enlarged distal clot entry tube tip.

[0021] In one embodiment, in the expanded configuration, the diameter of the distal-most portion of the catheter defined by the expandable member is greater than the diameter of the generally cylindrical lumen of the distal region of the catheter.

[0022] In one instance, in the expanded configuration, the expandable member extends distally beyond the distal-most end of the shaft.

[0023] In one embodiment, the expandable member comprises a balloon.In the expanded configuration, the balloon can be funnel-shaped with an enlarged distal access tip and a narrower proximal end.

[0024] In one instance, the balloon is integral to the distal tip of the catheter shaft.

[0025] The expandable member is formed from a polymer tube that is inverted such that a distal junction between the balloon and the catheter shaft is located within the balloon.

[0026] In one embodiment, the balloon includes regions having different properties from each other.

[0027] The balloon may include a proximal region, a distal region, and an intermediate region between the proximal region and the distal region, and wherein in the expanded configuration, the distal region expands to a greater extent than the proximal region.

[0028] In one case, at least one region has a different wall thickness than at least one other region.

[0029] In one instance, the wall thickness of the proximal and distal regions is greater than the wall thickness of the middle region.

[0030] In one embodiment, the wall thickness of the proximal region is greater than the wall thickness of the middle region and the distal region.

[0031] In one embodiment, the expandable member includes a proximal neck and a distal neck, the proximal neck having a first thickness and connected to a catheter shaft proximal to the distal end of the catheter, the proximal portion of the expandable member including a second thickness, the distal portion of the expandable member including a third thickness, and the distal neck inverted and joined to the distal end of the catheter shaft including a fourth thickness.

[0032] In one embodiment, the middle portion of the expandable member comprises a variable thickness that gradually decreases from the second thickness to the third thickness.

[0033] In one instance, the first thickness is greater than the second thickness, and the second thickness is greater than the third thickness.

[0034] In one embodiment, the fourth thickness is greater than the third thickness.

[0035] In one instance, the fourth thickness is greater than the third thickness.

[0036] In one embodiment, the first thickness is approximately the same as the second thickness in the deflated state, but greater than the second thickness in the inflated state.

[0037] In one instance, a band is disposed between a proximal region and a distal region of an expandable member, the band having a wall thickness greater than the wall thickness of the proximal region and / or the distal region to form a relatively non-expandable region such that the expandable member preferentially inflates proximal and distal to the band to provide a funnel-shaped cross-section.

[0038] In one instance, at least one of the regions is reinforced to limit expansion of that region.

[0039] In one embodiment, the proximal region includes reinforcements.

[0040] In one instance, the reinforcement comprises ribs.

[0041] The ribs may extend axially and / or radially along at least a portion of the proximal region.

[0042] In one embodiment, the material of the ribs is the same as or different from the material of the balloon.

[0043] In one instance, the expandable member in the collapsed configuration extends beyond the distal tip of the catheter shaft.

[0044] The expandable member extends beyond the distal tip of the catheter shaft by a distance of 0.5 mm to 3.5 mm.

[0045] In one embodiment, the catheter shaft includes a main lumen and an inflation lumen for inflating the expandable member.

[0046] The inflation lumen may extend within the wall of the catheter shaft.

[0047] In one embodiment, the inflation lumen and the catheter lumen are eccentric.

[0048] In another aspect, the inflation lumen and the catheter lumen are concentric.

[0049] In one instance, the inflatable expandable member includes an amorphous elastomeric polymer.

[0050] The elastomeric polymer may be a thermoplastic polyurethane elastomer.

[0051] In one embodiment, a portion of the shaft of the catheter includes an inflatable expandable member.

[0052] In one instance, the distal region of the catheter shaft includes an amorphous elastomeric polymer.

[0053] In one embodiment, the amorphous elastomeric polymer of the distal region of the catheter is a thermoplastic polyurethane elastomer.

[0054] In one instance, the distal portion of the shaft includes a first amorphous elastomeric polymer and the inflatable expandable member includes a second amorphous elastomeric polymer different from the first amorphous elastomeric polymer.

[0055] In one embodiment, a catheter shaft comprises a proximal region, a distal region, and an intermediate region between the proximal region and the distal region, and wherein the proximal region, the intermediate region, and the distal region of the shaft comprise materials having different stiffnesses.

[0056] In one instance, the proximal region of the catheter shaft comprises a polyamide, the distal region comprises a thermoplastic polyurethane elastomer, and the intermediate region comprises a polyether block amide copolymer.

[0057] In one instance, the catheter further includes an expandable marker band at or adjacent to the expandable member.

[0058] In one embodiment, a distal marker band is located beneath the expandable member.

[0059] In one instance, the radiopaque distal marker is generally tubular in shape with an axially extending slot configured to facilitate expansion of the marker.

[0060] In one embodiment, the clot capture catheter includes two or more expandable members.

[0061] In another embodiment, at least some of the expandable members have different compliances.

[0062] In one instance, a clot capture catheter includes an expandable balloon member mounted on a distal segment of the catheter, the balloon member including an inner balloon member positioned within an outer balloon.

[0063] In one embodiment, the elastic compliance of the balloon members varies.

[0064] In one instance, only the inner balloon is in communication with the inflation lumen to facilitate inflation.

[0065] In one embodiment, the inner balloon is configured to contact the outer balloon when inflated.

[0066] In one instance, in the expanded configuration, the effective diameter of the distal-most portion of the expandable member is at least 20% greater than the diameter of the lumen at the distal end of the catheter shaft.

[0067] In another instance, the effective diameter is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 100% greater than the diameter of the lumen at the distal end of the catheter shaft.

[0068] In one embodiment, the distal end region of the expandable member flares outwardly from the catheter shaft lumen at an angle.

[0069] In one embodiment, the opening angle is 10 to 60 degrees or 15 to 45 degrees.

[0070] In one embodiment, the expandable member includes features such as undulations and / or bends to facilitate expansion of the distal tip region.

[0071] In one instance, the inflatable member is inverted and joined to a catheter shaft at a proximal joining region, wherein the shaft comprises a plurality of layers including an outer sleeve, an intermediate layer, an inner liner, and a reinforcing braid or coil.

[0072] In one embodiment, the proximal end of the inflatable member is joined to the elongated shaft at a proximal joining area, and the other end of the inflatable member is inverted and joined to the intermediate layer at a joint, so that the middle section of the generally tubular polymer member forming the expandable member is positioned at the distal end of the catheter, and the portion of the tubular polymer member located between the joint and the middle section is joined to the distal section of the catheter shaft.

[0073] In one instance, a strip of material is mounted on the expandable member and proximally joined to the catheter body, and a distal end of the strip of material is bonded to the atraumatic distal catheter tip.

[0074] In one embodiment, a plurality of strips of material are positioned radially around the balloon.

[0075] In one instance, the strip of material comprises a low elastic compliance polymer such as PET.

[0076] In one embodiment, the expandable element is a composite construction comprising semi-rigid ribs interspersed with segments of resilient expandable material.

[0077] In one instance, the ribs extend parallel to the axis of the catheter.The ribs may extend in a helical configuration.

[0078] In one embodiment, the catheter includes a sealed, inflatable chamber adapted to be filled with a radiopaque fluid.

[0079] In one instance, a clot capture catheter includes a plunger for inflating and deflating an expandable member.

[0080] In another instance, a clot capture catheter includes a controller for moving a plunger to control inflation and deflation of the expandable member.

[0081] The controller may include a manual knob.

[0082] In one embodiment, the plunger is defined by a bellows.

[0083] In one instance, the clot capture catheter includes a spring to bias movement of the bellows.

[0084] In one embodiment, the cross-section of the distal tip of the expandable member in the expanded configuration is a non-uniform shape.

[0085] In one instance, the cross-section comprises an ellipse.

[0086] In one embodiment, a kit includes a clot capture catheter, a clot engaging device, and a microcatheter for the clot engaging device.

[0087] The clot engaging device is a stent retriever device.

[0088] In another aspect, the present invention provides a clot capture procedure comprising:-

[0089] providing a clot capture catheter having an inflatable member at a distal-most tip of the catheter;

[0090] advancing the clot capture catheter toward the clot while the inflatable member is in the collapsed configuration;

[0091] inflating an inflatable member at the distal end of the catheter so that the inflatable member extends outwardly from the distal-most end of the catheter to the vessel wall; drawing the clot into the catheter;

[0092] deflation of the inflatable member; and

[0093] Withdraw the catheter.

[0094] In one instance, the method includes applying suction to draw the clot into the catheter. Alternatively or additionally, the method includes engaging the clot with a mechanical device, such as a stent retriever, to draw the clot into the catheter.

[0095] In one embodiment, a clot capture procedure includes providing a microcatheter, advancing the microcatheter through a clot capture catheter, and deploying a clot engaging device from the catheter.

[0096] In another aspect, the present invention provides a method for capturing a clot, comprising:-

[0097] advancing the catheter through the vasculature to a location proximal to a target clot in the vessel;

[0098] Pass the clot with a microcatheter;

[0099] advancing a clot capture device through the microcatheter to the clot site;

[0100] retracting the microcatheter to deploy the clot capture device at least partially beneath the clot;

[0101] inflating an expandable member of the catheter to slow or stop flow in the vessel; retracting the clot capture device proximally toward the catheter;

[0102] Connect a syringe or pump to the proximal end of the catheter and apply suction to reverse blood flow in the vessel;

[0103] retracting the clot capture device and the captured clot into the tip of the catheter under suction;

[0104] continuing to retract the clot capture device under suction through and out of the catheter; and

[0105] Suction is stopped and the expandable member is deflated to restore blood flow to the vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] The invention will be more clearly understood from the following description of some embodiments of the invention given by way of example only, with reference to the accompanying drawings, in which:

[0107] Figure 1 is an isometric view of a clot retrieval catheter of the present invention;

[0108] Figure 2a to Figure 2d is a cross-sectional view taken through the shaft of a clot retrieval catheter of the present invention;

[0109] Figures 3a to 3e A cross-sectional view taken through the shaft and portion of the shaft of a clot retrieval catheter of the present invention;

[0110] Figure 4 A side view showing a method for manufacturing a catheter shaft;

[0111] Figure 5 is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0112] Figure 6a to Figure 6b is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0113] Figures 7a to 7c is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0114] Figures 8a to 8c is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0115] Figures 9a to 9d A view of a conventional prior art thrombectomy procedure;

[0116] Figures 10a to 10d is a view of a thrombectomy procedure using a clot retrieval catheter of the present invention;

[0117] Fig.11is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0118] Fig.12 is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0119] Fig.13 is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0120] Fig.14 is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0121] Fig.15 is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0122] Figures 16a to 16c is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0123] Fig.16d is a side view of a distal portion of a clot retrieval catheter of the present invention;

[0124] Figure 16e to Figure 16f A view of an expandable marker band of the present invention;

[0125] Figure 16h to Figure 16i is a view of another expandable marker band of the present invention;

[0126] Figure 17a to Figure 17b is a cross-sectional view of a distal portion of a clot retrieval catheter of the present invention;

[0127] Fig.17c for Fig.17a and 17b an isometric view of the distal end of the catheter;

[0128] Fig.18a is a simplified view of a distal portion of a clot retrieval catheter of the present invention;

[0129] Fig.18b For along Fig.18a A cross-sectional view taken along line AA in FIG.

[0130] Figures 18c to 18d is a cross-sectional view taken through the distal portion of a clot retrieval catheter of the present invention;

[0131] Figure 19a to Figure 19b is a view of the proximal hub of the clot retrieval catheter of the present invention;

[0132] Fig.20a and Fig.20b is an isometric view of the distal end of a clot retrieval catheter of the present invention; and

[0133] Fig.20c is a simplified illustration of a clot retrieval catheter of the present invention in use. Detailed Description

[0134] Specific embodiments of the present invention are now described in detail with reference to the accompanying drawings, wherein the same reference numerals represent the same or functionally similar elements. The terms "distal" or "proximal" are used in the following descriptions of positions or directions relative to the treating physician. "Distal" or "towards the distal side" is a position far from the physician or a direction away from the physician. "Proximal" or "towards the proximal side" or "approaching" is a position close to the physician or a direction toward the physician.

[0135] Accessing the cerebral, coronary, and pulmonary vessels involves the use of a number of commercially available products and conventional procedural steps. Access products such as guidewires, diagnostic catheters, microcatheters are described elsewhere and are commonly used in catheterization laboratory procedures. In the description that follows, it is assumed that these products and methods are used in conjunction with the devices and methods of the present invention and do not require detailed description.

[0136] The following detailed description is merely exemplary in nature and is not intended to limit the invention or its application and use. Although the invention is described in many cases in the context of treating intracranial arteries, the invention may also be used in other body passages as described above.

[0137] Figure 1 100 shows a clot capture catheter of the present invention, which includes a distal inflatable portion 101 attached to a distal shaft 102, which in turn is attached to a shaft mid-section 103, which is attached to a shaft proximal section 104. A proximal hub 105 is connected to the proximal end of the catheter shaft and includes a Luer attachment 106 and a side port 107. The side port 107 provides access to an inflation lumen that passes from the hub through the wall of the catheter shaft to the inflatable portion 101. The inflation lumen is shown in FIG. Figure 2a to Figure 2d In the cross-sectional view of the shaft shown in .

[0138] The inflatable portion 101 of the distal end preferably comprises an amorphous elastomeric polymer so that it can be stretched / strained to at least twice and up to 5 times its uninflated diameter under inflation pressure, and recover most or all of its unexpanded shape when deflated. This requires the material to withstand at least 200% and ideally 500% or more elastic strain, ideally with minimal plastic deformation or hysteresis. The cross-linking of polymer chains greatly facilitates such high levels of recoverable strain, so thermosetting materials such as silicone rubber may be a good choice. However, silicone is not a material that is easy to join to a second material because it is not easy to melt and is not easily miscible with another material to form, for example, a strong and low-profile welded joint. For this reason, polyurethane elastomers are also materials suitable for the balloon of the present invention. In particular, thermoplastic polyurethane elastomers will become ideal materials because they can be melted as part of a welding or joining process, or can be solvent bonded or bonded in an adhesive manner.

[0139] Figure 2a to Figure 2d Shown by Figure 1 A plurality of possible cross-sectional views of various embodiments of the catheter shaft are shown, Figure 1 As shown in the section line 108 in FIG. Figure 2a A shaft 150 is shown having an inner lumen 152 and a single inflation lumen 151 . Figure 2b A shaft 160 is shown having an inner lumen 162 and three gas-filled lumens 161 . Figure 2c A shaft 170 having an inner lumen 172 and a single oblong crescent-shaped inflation lumen 171 is shown. Figure 2d A shaft 180 is shown having an outer shaft wall 184, an inner shaft wall 183, and an inner cavity 182. The space between the inner shaft wall and the outer shaft wall forms an inflatable cavity 181. In all of these shaft variations, the shaft construction may also include a low friction coating or lining (such as PTFE) on the inner cavity wall. Reinforced braids and / or coil wires or fibers may be used to provide hoop strength (to withstand suction through the lumen without collapsing) and kink resistance. The main wall of the shaft may include one or more materials, with thermoplastic polymers such as polyurethane, Pebax, and polyamide being preferred examples. In one example of a preferred shaft material construction, one or more grades of polyurethane are used for the very distal segments of the balloon and catheter; one or more Pebax (polyether block amide copolymer) materials are used for the middle segment of the catheter; and one or more polyamide materials are used for the proximal segment of the catheter shaft. This series of materials provides increasingly higher hardness and Young's modulus (or stiffness) so that a very flexible distal shaft region can smoothly transition to a more rigid proximal shaft region. The polyether block amide material has the advantage of being able to bond with both polyurethane and polyamide, although polyurethane and polyamide cannot be easily bonded with each other.

[0140] The plenum cavity may be formed in a number of different ways as described below, and may be lined with one or more materials having a higher melting or softening point than the main wall of the shaft (such as PTFE, FEP, PET or polyimide) to facilitate the formation of the plenum cavity and the subsequent removal of any forming mandrel used in the process. Figure 2a to Figure 2c As shown in , the shaft can be designed to be eccentric to provide sufficient wall thickness to form an inflation lumen without causing the overall diameter of the catheter to be too large. Alternatively, a concentric design can be used, such as Figure 2d as shown in .

[0141] Figures 3a to 3e A series of cross-sectional views taken through a portion of the shaft of a clot retrieval catheter of the present invention are shown, illustrating one embodiment of how the inflation lumen may be formed. In this embodiment, Figure 3a The elongated tube 200 in the embodiment is provided with three core axes 201, so that the tube is deformed into the following Figure 3b The assembly of tube 200 and wire 201 is then placed on top of the elongated shaft 203, and the outer sheath 202 is placed over both, as shown in FIG. Figure 3c Heat and pressure are then applied as shown by line 204 (optionally mediated by another outer sheath or heat shrink, not shown) to laminate the entire assembly together. This process fuses the outer sheath 202 to the inner elongated shaft 203 and surrounds the inflation lumen 200 with its inner core axis 201, as shown in FIG. Figure 3d The mandrel is used to prevent the air-filled cavity from collapsing and maintain its desired shape during the forming process. Once the forming process is completed, the mandrel is removed so that the air-filled cavity 206 is open and unobstructed from passing through the composite shaft 205, as shown in FIG. Figure 3e Many variations of this design and process are possible, for example the inflatable tube may be made of a low friction material such as PTFE, in which case it may remain in place when the core axis is removed, or it may be removed on its own with or after the core axis. In another embodiment, the inflatable tube is made by solution casting and comprises polyimide or other relatively high modulus material that can be manufactured to a wall thickness as small as 0.001 or less and still maintain a high degree of structural integrity. Another advantage of polyimide as a material of choice is that it will not melt during the catheter forming / fusion process, thereby minimizing the challenges of finally removing the core shaft. The core shaft itself may be metallic or formed of a very high tension polymer and is ideally coated with a low friction material such as PTFE or polyparaxylene.

[0142] Figure 4The preferred manufacturing method of the catheter shaft of the present invention is shown. The contact surface between two sections of polymer tubes (251 and 252) with different hardness and / or elastic modulus is shown as being joined together at points along the length of the shaft by a thermoforming process and a pressure forming process involving an external heat shrink tube 252 and a heat source 253. The catheter shaft needs to have a stiffness gradient along most of its length to seamlessly transition from a rigid and pushable proximal end to a highly flexible and non-traumatic distal end. This stiffness gradient does not need to be abrupt, which may become a problem for the joint between the two shaft materials. As shown in region 254, feathering the end of the tube to be joined enables a more gradual stiffness transition from the first material 250 to the second material 251. In this way, the % of each material in a given cross-section of the shaft can vary over a greater length than the length that can be achieved with the minimum amount of material mixing produced in a simple docking. If necessary, the structure shown enables the overlap region 254 to extend to a length greater than 10 mm, but the overlap length is preferably between 1 mm and 5 mm.

[0143] Figure 5 Shows something like Figure 1 1 is a cross-sectional side view of the distal end of the clot retrieval catheter 300 of the catheter 100 shown in FIG. The catheter includes a substantially cylindrical elongated tubular shaft 302, to which an inflatable distal balloon 301 is mounted. The distal balloon 301 is configured so that a funnel-shaped profile is formed when expanded. The funnel-shaped profile can be achieved by the position and wall thickness profile of the expandable membrane that forms the balloon, and / or can be achieved by using additional elements to help expand the catheter end, as described in more detail elsewhere in this document. Line 303 represents the centerline of the catheter end area. Lines 305 and 306 are lines parallel to the centerline 303, indicating the diameter 311 of the opening at the farthest side of the catheter. Points 309 and 310 indicate the location where lines 305 and 306 intersect with the distal side 304, indicating the range of the opening diameter of the distal end of the catheter. Lines 307 and 308 are lines parallel to centerline 303 and indicate the diameter 312 of the catheter lumen into which the clot must ultimately be squeezed in order to be fully removed by the catheter.

[0144] A key feature of this cross section is that the effective diameter 311 of the most distal portion of the catheter is significantly larger than the diameter 312 of the generally cylindrical lumen of the distal region of the catheter. The distal end of a conventional clot retrieval catheter may have some rounding or chamfering to form a very small lead-in tip, but this has little effect on reducing shear stresses on the clot and avoiding loss of fragments. The disclosed invention forms a true funnel shape without the need for pull wires or other such rigid and cumbersome mechanical actuation. The funnel is formed so that the diameter 311 is ideally at least 20% larger than the diameter 312, and preferably 50% or 100% larger than the diameter 312. Thus, if the diameter 312 is 0.084" (as may be the case for a typical catheter of this type), the diameter 311 is at least 0.101" and ideally up to 0.126" or 0.168" or more.

[0145] The wall thickness profile of the inflatable member 301 is very similar to Figure 7b The wall thickness profile of the inflatable member 400 is shown in FIG. 4 and reference may be made to the description provided therein.

[0146] Figure 6a and Figure 6b Simplified cross-sectional views of the distal region of the clot retrieval catheter of the present invention in the inflated state and the uninflated state are shown respectively. The catheter includes an elongated shaft 320 having an inner liner 323, a distal end section 326 and an inflatable portion 328. The inflatable portion 328 has different wall thicknesses in different regions to produce the desired shape and effect when inflated. The low wall thickness region 321 is subjected to the highest strain and therefore expands the most when inflated, forming a balloon-like shape that can be used to limit or prevent blood flow through the catheter. The high wall thickness region 322 is subjected to much lower strain at the same stress (and pressure) level and therefore cannot expand to the same diameter as the lower wall thickness region, however it is under axial tension due to the pressure in the inflatable member, and the tension continues to pull and help to open the end section 326 to an opening angle 330. The opening angle 330 is preferably between 10 degrees and 60 degrees, and most preferably between 15 degrees and 45 degrees. The thin wall thickness region 327 acts as a hinge to minimize the resistance to the end opening. Additional features such as bends or undulations may also be provided to this region to aid in the flaring of the ends. Figures 16a to 16i An example of this is provided. An additional thin-walled hinge (not shown) may be provided at region 329 to assist in the opening of the tip region into a funnel-like shape. A marker band 324 is shown below the inflatable portion and serves a dual purpose: providing visibility of the catheter tip under fluoroscopy and providing hoop strength to the catheter shaft to prevent deformation under inflation pressure.

[0147] Figures 7a to 7cA simplified cross-sectional view taken through the distal portion of a clot retrieval catheter of the present invention is shown, illustrating how varying the wall thickness profile of the inflatable portion of the catheter can be used to affect the shape of the inflation balloon.

[0148] exist Figure 7a , a proximal neck 351 of an inflatable member 354 comprises a first thickness and is connected to a catheter shaft 350 proximal to the distal end of the catheter. A proximal portion 352 of the inflatable member comprises a second thickness, while a distal portion 353 comprises a third thickness, and a distal neck 355 that is inverted and joined to the distal end of the catheter shaft 350 comprises a fourth thickness. An intermediate portion 356 of the inflatable member 354 comprises a variable thickness that gradually decreases from the second thickness 352 to the third thickness 353. In one embodiment, the first thickness is greater than the second thickness, and the second thickness is greater than the third thickness. In one embodiment, the fourth thickness is greater than the third thickness. In one embodiment, the fourth thickness is greater than the first thickness. In one embodiment, the first thickness is generally equal to the second thickness in a deflated state, but greater than the second thickness in an inflated state. This thinner cross-section of the distal segment of the inflatable member causes the segment to preferentially inflate and expand distally, forming the desired funnel-shaped cross-section. However, overinflation of such a cross-section may cause the distal segment 356 to impact the catheter lumen, a problem that may be caused by Figure 7b and the profiles shown elsewhere in this document.

[0149] Figure 7b Another embodiment of the distal portion of the clot retrieval catheter of the present invention is shown, which has a slightly different wall thickness profile. In this case, the wall thickness of the proximal 401 and distal 403 portions of the inflatable member 400 is greater than the wall thickness of the middle 402 portion. This thinner profile of the middle section of the inflatable member causes this section to be preferentially radially inflated, causing axial strain in the proximal and distal sections. This axial strain causes the distal portion 403 to lift and open, forming the desired funnel-shaped profile.

[0150] Figure 7c Another embodiment of the distal portion of the clot retrieval catheter of the present invention is shown, having a slightly different wall thickness profile. In this case, a band 451 of greater wall thickness is disposed between the proximal and distal regions of the balloon 450 to form a relatively non-expandable region 451, forcing the balloon to preferentially inflate proximally and distally of the band, thereby forming a distal "bump" 452 and thus the desired funnel-shaped profile.

[0151] In each of these embodiments, the wall thickness of the thinner wall segments decreases by a greater % when inflated than the wall thickness of the thicker wall segments, which enables the uninflated wall thickness to be used to control the inflated shape of the inflatable member.

[0152] Figures 8a to 8cA partial cross-sectional view taken about centerline 502 through the distal portion of a clot retrieval catheter of the present invention is shown, illustrating an example of how an inverted member (tubular or otherwise) may be used to form an inflatable member of a catheter.

[0153] Figure 8a Inflatable member 500 is shown, which is joined to elongated shaft 501 at proximal engagement area 507. Axle 501 includes multiple layers, which include outer sleeve 510, intermediate layer 503, liner 505 and reinforced braid or coil 504. Axle 501 also includes an internal inflation chamber (not shown) as described elsewhere. Inflatable member 500, catheter outer sleeve 510 and catheter intermediate layer 503 are preferably all made of the same family material (such as polyurethane), or at least made of a material with compatible components so that they can be joined together by heat and pressure or solvent bonding process. The proximal end of inflatable member 500 is joined to elongated shaft 501 at proximal engagement area 507, and the other end of inflatable member 500 is reversed and joined to intermediate layer 503 at joint 508. Thus, an intermediate section of the generally tubular polymer member 511 forming the inflatable member 500 is positioned at the distal end of the catheter and a portion 509 of the tubular polymer member 511 located between the joint 508 and the intermediate section is laminated to a distal section of the catheter shaft (including an inner lining and reinforcing braid or coil).

[0154] Figure 8b Shown with Figure 8a , except that in this case, the inflatable member 550 has a shorter inverted length and the intermediate layer 503 of the shaft 501 extends substantially to the distal end of the catheter liner and braid. Therefore, the junction 508 between the inverted portion of the inflatable member 550 and the shaft can be made closer to the distal end of the catheter.

[0155] Figure 8c Shown with Figure 8a A very similar construction is shown in , except that in this case the inflatable member 600 is formed by an extended inverted portion of the middle layer 503 of the shaft 501 .

[0156] Figures 9a to 9d (Prior Art) illustrates one of the huge problems with conventional balloon guide catheter technology, which can cause serious harm to the patient during a clot retrieval procedure.

[0157] Figure 9a A clot retractor device such as a stent retriever 701 is shown retracting a clot or thrombus 702 through a vessel 700 into a distal tip 705 of a balloon guide catheter 703. The balloon guide catheter 703 includes a balloon 704 positioned just proximal to its distal end portion 710. A typical thrombectomy procedure involving a stent retriever includes:

[0158] Advancing a balloon guide catheter 703 (or similar guide or sheath) through the vasculature to a location proximal to the target clot using conventional intravascular access techniques;

[0159] A microcatheter is passed through the clot, usually over a guidewire.

[0160] Advance the stent retriever through the microcatheter to the clot site;

[0161] retracting the microcatheter to deploy the stent retriever at least partially beneath the clot;

[0162] Inflating the balloon 704 of the balloon guide catheter 703 to slow or stop flow in the vessel 700;

[0163] Retract the stent retriever proximally toward the balloon guide catheter;

[0164] Connect a syringe or pump to the proximal end of balloon guide catheter 703 and apply suction to reverse blood flow in vessel 700;

[0165] Retract the stent retriever and captured clot into the tip 705 of the balloon guide catheter 703 under suction;

[0166] Continue to retract the stent retriever under suction, passing through and out of the balloon guide catheter 703;

[0167] • Stop suction and deflate balloon 704 to restore blood flow to vessel 700.

[0168] Figure 9a A stage of the procedure is shown where the stent retriever 701 and clot 702 are to be drawn back into the tip 710 of the balloon guide catheter 703. The balloon 704 is inflated and the operator has begun suctioning through the balloon guide catheter 703 to reverse the blood flow in the vessel 700 and help draw the clot safely back into the tip 710 of the catheter. However, because the tip 710 extends distally at the distal end of the balloon 704, there is a dead space 706 around the distal tip 710 just distal to the balloon 704. There is little or no reverse flow to pull the clot or any clot fragments into the catheter tip.

[0169] Figure 9bThe stage of the above-mentioned procedure is shown, wherein the stent retractor 701 and the clot 702 are being withdrawn into the tube head 710 of the balloon guide catheter 703. When the clot is pulled into the catheter, it must be deformed into a certain shape to fit into the catheter lumen. The required degree of deformation depends on the relative size of the clot and the catheter lumen, and also depends on the degree to which the stent retractor compresses the clot against the catheter. A greater degree of deformation will produce a higher level of shear stress on the clot, which is usually concentrated at the end of the catheter because the clot undergoes a sudden change in shape here. This can tear the clot and release fragments, especially if the clot does not have a very organized fibrin structure and / or if a dissolving drug such as tPa has been provided to the patient. In this case, the clot fragments 707 and 708 have been released from the clot and are located in the dead space 706, and the shear stress on the clot induces an overhanging area 709, which is pushed to the proximal side of the distal tube head 705 of the catheter and there is a risk of tearing away from the main body of the clot.

[0170] Fig.9c The results of the high shear forces described previously combined with the dead space 706 are shown: Figure 9b The clot fragments 707 and 708 shown in FIG. 7 have been joined by a third fragment 709 and the reverse flow induced by suction through the vessel into the catheter has failed to pull them out of the dead space and into the catheter tip.

[0171] Figure 9d A later stage in the procedure is shown after the stent retriever 701 and any captured clot have been removed from within the catheter 703. At this stage, suction through the catheter is stopped and the balloon 704 is deflated. This restores blood flow to the vessel 700 distal to the catheter, so that the clot fragments 707, 708 and 709 are released and flow downstream, where they may obstruct one or more vessels, potentially causing serious injury or even death to the patient.

[0172] Any suitable clot capture device may be used as part of the kits and procedures described herein. The clot capture device may be of the stent retriever type. The clot capture device may be as described in any of our WO2012 / 120490A, WO2014 / 139845A, WO2016 / 083472A and / or WO2017 / 089424A.

[0173] Figures 10a to 10d Shown with Figures 9a to 9d A similar thrombectomy procedure is performed as shown in FIG, but this time using the clot retrieval catheter 803 of the present invention. The same procedural steps are performed as above, but because the catheter 803 has the following two advantages: 1) there is little or no dead space distal to the balloon; 2) the distal tip is open to minimize shear stress on the clot, so in this case the clot is completely retrieved into the catheter and no clot fragments are lost when the balloon is deflated.

[0174] Fig.10a A clot retrieval device, such as a stent retriever 801, is shown retrieving a clot or thrombus 802 through a vessel 800 into a distal tip 805 of a clot retrieval catheter 803. The clot retrieval catheter 803 includes a balloon 804 positioned at its distal end. Figures 9a to 9d As shown, balloon 804 has been inflated to restrict flow in vessel 800 , and suction through catheter 803 may be used to further assist the clot in entering catheter tip 805 by reversing blood flow in vessel 800 .

[0175] Fig.10b A stage of the above-described procedure is shown in which the stent retriever 801 and clot 802 are being withdrawn into the tip 805 of the catheter 803. The funnel-shaped cross-section 806 of the catheter 803 minimizes shear stresses induced in the clot as it is withdrawn into the catheter, and there is little or no dead space between the balloon and the tip to trap any debris (such as the illustrated debris 807) that is generated or otherwise present therein.

[0176] Fig.10c The benefit of having no dead space is shown, namely that after the stent retriever 801 and the main body of the clot 802 are pulled back, the debris 807 is safely pulled into the catheter lumen by aspiration and reverse flow through the catheter.

[0177] Fig.10d A later stage in the procedure is shown after the stent retriever 801 and captured clot 802 have been removed from within the catheter 803. At this stage, suction through the catheter is stopped and the balloon 804 is deflated. This restores blood flow to the vessel 800 distal to the catheter, restoring oxygenated blood safely to the distal vasculature without releasing any harmful clot fragments.

[0178] Fig.11An embodiment 900 of the present invention is shown, which shows a partial cross-section of the distal end of a clot capture catheter. Two inflatable balloon members 902 and 906 are mounted on the distal section of a catheter 905, wherein one balloon member 906 is positioned within the outer balloon 902. One or both inflatable balloon members may be communicated with an inflation chamber to allow fluid to be injected into the balloon, thereby inflating it. The elastic compliance of the two inflatable members may vary as the flexibility of balloon 902 is lower than that of balloon 906, and vice versa. In one case, only balloon 906 is communicated with the inflation chamber to facilitate expansion. When this balloon 906 expands, it blocks the artery or vessel at its deployment location to improve the effectiveness of suction and retracting the clot into the catheter. In addition, when balloon 906 expands, it contacts balloon 902, forcing it to expand and increase in diameter. The flexibility of balloon 902 ensures that as the diameter increases, the length of the balloon decreases, thus pulling the distal end of catheter 904 into a funnel shape that is conducive to the retrieval of the clot. The joint 903 between balloon 902 and distal end 904 is positioned at or near the distal end of the catheter to facilitate the formation of the funnel shape. The flexibility of one or both of these balloons can be different from the circumferential direction to the longitudinal direction parallel to the catheter axis. This will facilitate preferential expansion in one direction when fluid is injected under pressure through the inflation cavity.

[0179] Fig.12Another embodiment 920 of the present invention is shown, in which a plurality of expandable balloons are mounted on a catheter. This figure is also a partial cross-sectional view, and in this embodiment, an expandable member 922 is mounted at the distal end of a catheter 924. The distal expandable member 922 forms an introduction end shape 921 to facilitate the retraction of the clot into the catheter. The installation of multiple balloons or expandable members on the catheter allows the functional separation of the expandable balloons and allows different expandable elements to meet different performance attributes. For example, in this case, the distal balloon 922 is conducive to the retraction of the clot and can concentrate the catheter end in the vessel when the balloon 923 blocks the vessel and provides flow retardation. Therefore, the diameter of the distal balloon 922 can be smaller than the vessel in which the catheter is deployed, and can be a "non-flexible" or low-flexibility balloon, while the balloon 923 positioned more proximally can be a soft, flexible balloon having a diameter greater than the vessel to provide atraumatic vessel occlusion. The distance between the balloons along the catheter axis can vary between 2 mm and 150 mm, and in a preferred embodiment, between 2 cm and 10 cm. Because the distal balloon has a smaller diameter than the vessel, it can be inflated to a higher pressure without causing any expandable strain to the vessel. This higher pressure can bring benefits, and is about to concentrate the catheter end part in the vessel. Positioning the balloon 923 that provides flow retardation at the proximal side of the catheter end is conducive to designing the catheter so that the balloon is positioned in a more suitable vessel segment than the position of the distal end, for example, with an increased bone support or externally supported vessel segment. Alternatively, the proximal balloon can be positioned in the proximal segment of the internal carotid artery, or even positioned in the common carotid artery.

[0180] Fig.13 Another partial cross-sectional view of a catheter with multiple balloons is shown. In this embodiment 940, balloon 942 is located within balloon 943. Both balloons can be communicated with the inflation chamber and can be inflated simultaneously or separately as desired by the operator. Balloon 942 is a low compliance balloon with a diameter suitable for partially self-centering the catheter tip in the vessel. The higher compliance softer outer balloon 943 provides atraumatic vessel occlusion prior to clot aspiration or retraction, thereby providing flow retardation. This vessel occlusion can occur with equal pressure in both balloons, or increased pressure can be applied to one of the balloons depending on the stage of the procedure.

[0181] Fig.14 A partial cross-sectional view of a clot retrieval catheter 960 is shown having an inflatable balloon 963 mounted at the distal tip. Figures 8a to 8c and Figures 9a to 9d The benefits of attaching the balloon at the distal tip of the catheter are shown so that there is no "dead space" between the distal tip and the balloon and the risk of clot shearing is subsequently reduced when the clot is retrieved into the catheter. Fig.14It is shown how a balloon 963 may be attached to a catheter 964 by inverting the neck 962 of the balloon to achieve optimal positioning at the end 961. One method of assembly is to glue or weld the neck of the balloon 962 to the end of the catheter 961, then invert the balloon and join the proximal neck 965 of the balloon to the catheter 964. Joining the balloon to the catheter in this manner not only reduces clot shearing, but also allows the atraumatic end of the catheter 961 to open during clot retrieval and act as an introduction port for the clot.

[0182] Fig.15 Shown with Fig.14 980. However, in this embodiment 980, the distal neck 982 of the balloon 983 is attached to the inner surface of the catheter tip 981. In this design, the bonding of the distal neck 982 can be completed by inverting the balloon neck in the catheter before or after the proximal neck bonding.

[0183] Fig.16a 1 is a partial cross-sectional view of the distal end 1000 of the present invention, showing a schematic diagram of an expandable member 1001 mounted on a catheter shaft 1004. The expandable element 1001 is proximally joined to the catheter at 1005 and the distal end 1003 of the catheter. The neck of the expandable element 1002 is shown as being inverted at the junction with the end 1003, so that the element 1001 is fully expanded to the end 1003, reducing the risk of clot shearing as discussed elsewhere in this patent. In addition, as the element 1001 expands, it applies tension to the catheter end 1003. In this embodiment, the distal end segment 1006 has a lower bending stiffness than the catheter segment 1004, so that the end 1003 can be opened and expanded into a funnel shape under tension to facilitate improved clot retrieval performance.

[0184] Fig.16b Shown with Fig.16a1026 is a cross-sectional view of a distal catheter structure similar to the device shown in the schematic diagram. The expandable element in this embodiment is a balloon 1020, which is joined to a catheter 1026 at the proximal end of the balloon 1022. The distal end of the balloon is inverted and welded to a catheter material 1027 to form a distal end 1023. The catheter 1026 is configured so that the material 1027 protrudes distally of the catheter reinforcement braid 1025 and is located below the inflation chamber 1021. The inflation chamber 1021 provides a channel for introducing fluid into the balloon 1020 for expansion. When the balloon is expanded, the tension in the balloon 1020 pulls the end 1023 (the distal side of the braid 1025) into a funnel shape to improve the effectiveness of clot removal. A distal radiopaque marker 1024 is incorporated into the catheter structure to indicate the position of the distal end in the vascular system under fluoroscopic fluoroscopy. The radiopaque marker 1024 is formed into a shape that can be easily expanded so as not to restrict the expansion of the catheter tip 1023 .

[0185] Fig.16c 1 is a partial cross-section of the distal end of another catheter of the present invention. It is shown in an expanded configuration, and in this case, the balloon neck 1040 is bonded to the catheter material 1041, which protrudes above the liner 1042 and the braid. The radiopaque marker 1043 is shown expanded to facilitate the distal catheter end to form a funnel or lead-in shape 1026.

[0186] Fig.16d A distal view of a catheter 1060 with a tip 1063 in an unexpanded configuration is shown. This image shows how the distal tip material is formed in corrugations 1062 to facilitate expansion into a funnel shape when the balloon is inflated. Radiopaque markers 1061 are formed around corrugations 1062, but still have expandability.

[0187] Figure 16e to Figure 16g An isometric view, a side view, and an end view of an optional radiopaque distal marker 1080 for incorporation into a clot capture catheter are shown, respectively. The marker is formed of a highly radiopaque material, such as gold, platinum, or tungsten, and is tubular in shape with a slotted cutout 1081 to allow the marker to expand. Alternatively, a nitinol marker coated with gold may be used so that it can return to its original shape after the balloon is deflated. The benefit of a marker of this shape is that it prevents the catheter tip from collapsing inwardly toward the centerline of the catheter, thereby reducing the aspiration cavity when the balloon is inflated.

[0188] Figure 16h and Fig.16iA side view and an end view of a similar expandable radiopaque marker 1090 are shown, respectively, with an increased slot width 1091 to enhance bonding with the catheter tip material. The marker is also expandable while limiting the reduction in diameter under external pressure. The use of a radiopaque marker or other reinforcement to prevent the inner diameter from decreasing when the balloon is inflated allows the use of a softer catheter tip material.

[0189] Fig.17a 1 is a cross-sectional view of another embodiment of the present invention. The figure shows the distal end of a clot retrieval catheter 1100 in an introduction configuration prior to expansion of an expandable element 1107. The catheter is configured to have an expandable element or balloon 1107 mounted on a main body section 1109 of the catheter. The balloon is bonded at the proximal and distal ends at 1105 and 1104, respectively, and is connected to an inflation chamber (not shown) to facilitate expansion. A material strip 1108 is mounted on the balloon and is joined to the catheter body 1109 proximally 1106. The distal end of the material strip 1108 is bonded to the atraumatic distal catheter tip 1102. In this configuration, the distal end of the strip 1108 is inverted 1103 prior to being joined to the catheter tip 1102. Multiple material strips 1108 are positioned radially around the balloon 1107.

[0190] Fig.17b The device 1100 is shown in its deployed or expanded configuration. Fluid has been injected into the balloon 1134 to expand it and occlude the vessel, causing flow retardation to increase the effectiveness of clot retrieval. In this embodiment, the strips of material 1133 are made of a low elastic compliance polymer such as PET with a thin wall. When the balloon 1134 is expanded, these strips of material 1133 are under tension, and this tension deforms the atraumatic end of the catheter 1132, causing the distal edge to expand and form a funnel shape 1132. By inverting the ends 1131 of the strips 1133 before joining to the catheter end, it ensures that the tension applied to the end is at the distal end, forming a larger diameter funnel shape.

[0191] Fig.17c For Fig.17b 1160. In this case, a strip of material 1163 is positioned radially around a balloon 1160 and joined to the catheter proximal to the balloon at 1164. The distal end of the strip 1163 is inverted 1161 and bonded to the catheter tip 1162. Inflation of the balloon 1160 pulls out the strip of material 1163, applying tension to the catheter tip 1162, thereby forming a funnel shape.

[0192] Fig.18a1 is a cross-sectional schematic diagram of another embodiment of the present invention. The distal end 1200 of the catheter is composed of a distal balloon 1201 mounted on a catheter shaft 1203. As previously described, when the balloon 1201 is expanded, it provides flow retardation in the vessel by blocking the flow. In addition, the balloon expansion applies tension to the catheter end 1202, forming it into a funnel shape, thereby improving the introduction end of the clot, reducing clot shearing and improving the effectiveness of aspiration and clot retrieval with a stent retriever.

[0193] Fig.18b Based on Fig.18a AA of , shows a composite balloon structure, which consists of semi-rigid ribs 1222 interspersed with segments of elastic expandable material 1221. When fluid is introduced into the balloon through an inflation chamber (not shown), the pressure increases and the diameter of the soft segment 1221 expands, causing flow obstruction in the vessel. The rib 1222 may have a different hardness from the expandable segment 1221, which will more effectively transmit the pulling force to the distal end and enhance the ability of the balloon to expand the end to form a funnel shape. The rib 1222 may be co-extruded with the balloon material, or may be formed by integrating wire or other materials into the balloon extrudate. The rib may extend parallel to the axis of the catheter, or may be formed as a spiral structure to enhance the flow retardation ability of the balloon.

[0194] Fig.18c Section AA is shown in a non-expanded configuration, wherein the rib 1242 and the expandable segment 1241 are concentric during introduction of the catheter into the target location.

[0195] Fig.18d An alternative cross-sectional view of a balloon in a non-expanded configuration is shown. In this embodiment, the balloon 1260 is formed from a single profile extrusion having varying wall thicknesses around the circumference. The regions 1261 having reduced wall thickness expand under pressure, thereby forming flow retardation in the vessel, while the segments 1262 having increased wall thickness act as ribs that apply tension to the atraumatic catheter tip, thereby causing it to expand.

[0196] Fig.19aA stylized view of the handle or proximal region of one embodiment of a clot retrieval catheter 1300 of the present invention is shown, wherein the balloon 1301 can be inflated and deflated without the need for pre-preparation or flushing of the inflation area. This can be achieved through a sealed system, wherein the inflation chamber and inflation area are evacuated of all air and then filled with a sterile radiopaque solution. Thus, the operator only needs to turn a threaded knob or actuator 1307 to inflate the balloon 1301 to the desired diameter. The catheter 1300 includes an elongated shaft 1308 having an inflatable balloon 1301 at its distal end and a proximal hub assembly 1302 at its proximal end. The shaft and balloon can be constructed according to any of those previously disclosed herein. The proximal hub assembly includes an inflation controller 1306, a side port 1303 (optional), a preparation port 1311, and a proximal connector 1305. The proximal connector 1305 may be a rotary hemostatic valve or may simply be a luer or connector to which a valve or other luer, connector or fitting may be attached and / or through which other catheters or devices may be advanced or retracted. The sterile radiopaque solution contained within the chamber 1314 within the inflation controller 1306 may include a contrast agent such as an iodine solution.

[0197] Fig.19b Shown by Fig.19a 13. A cross-sectional view of a portion of the proximal hub assembly 1302 of the catheter 1300 of FIG. 13. Clockwise rotation of the threaded knob 1307 causes the end 1315 of the knob 1307 to compress the bellows 1310. This in turn reduces the volume of the chamber 1314 within the bellows 1310, forcing the fluid (which may be a sterile contrast agent) to flow out of the chamber and into the inflation lumen 1313, which passes from the inflation controller through the elongated shaft 1308 to the distal inflatable balloon 1301. This in turn inflates the balloon, and the degree of inflation can be controlled by controlling the depth to which the knob is screwed into the inflation controller. A transparent inflation controller body 1306 can be used, through which the dark / opaque knob can be seen, allowing the operator to align the end of the knob 1315 with the appropriate marking on the controller body. Counterclockwise rotation of knob 1307 allows bellows chamber 1310 to expand, and this expansion may be assisted by coil spring 1309. This expansion pulls fluid back from the balloon through the inflation port, causing the balloon to deflate.

[0198] Preparation port 1311 and sealing cap 1312 are used to empty, fill and seal the device before use. In a preferred embodiment, these steps are performed by the manufacturer and the device is provided to the customer for use.

[0199] In alternative embodiments, these evacuation, priming, and sealing steps may be completed by a second operator (such as a catheterization lab nurse or technician or colleague) prior to use of the device by the first operator.

[0200] Fig.20a The distal end of various embodiments of the present invention is shown with a balloon 1402 mounted on a catheter shaft 1401. The balloon 1402 is shown in an expanded configuration and the distal tip 1403 is formed into a non-uniform shape. The tip 1403 still provides an introduction point for the clot during retrieval, thereby improving efficacy and reducing clot shear. The shape of the distal tip can be symmetrical and aligned with the curved element of the catheter shaft.

[0201] Fig.20b An alternative embodiment is shown in which the atraumatic distal tip 1423 forms an eccentric shape during introduction and can also expand to form an eccentric introduction end or funnel for the clot.

[0202] Fig.20c shows how to Fig.20b A catheter similar to the catheter of the present invention is positioned in the neurovascular system 1441 so that the balloon 1440 forms a flow blockage and the eccentric end 1443 provides an introduction end for clot retrieval. In one embodiment of such a system, the catheter shaft 1442 is biased to have a curved shape in an unconstrained state to help properly orient the eccentric balloon end to the vascular system. In one embodiment, the bend includes a bend proximal to the balloon 1440, as shown. In another embodiment, the bend includes a more proximal bend that is designed to be positioned within the patient's aortic arch. In yet another embodiment, the catheter includes two such bends. In yet another embodiment, the catheter includes a plurality of bends. In yet another embodiment, the catheter includes a manipulable element by which a bend can be selectively applied to the catheter during or after the catheter is advanced through the vascular system to the target site.

[0203] It will be apparent from the above description that, although specific embodiments of the present invention have been illustrated and described, various modifications may be made without departing from the spirit and scope of the present invention. For example, although the embodiments described herein relate to specific characteristic structures, the present invention includes embodiments having combinations of different characteristic structures. The present invention also includes embodiments that do not include all of the specific characteristic structures described.

[0204] The present invention is not limited to the embodiments described above, the construction and details of which may vary.

Claims

1. A clot capture catheter, comprising an elongated tubular shaft having a proximal end, a distal end, and an inflatable expandable member at the distal end, the expandable member being capable of being inflated from a collapsed delivery configuration to an expanded configuration, wherein in the expanded configuration, the expandable member extends to at least the distal-most end of the elongated tubular shaft and extends radially outward from the elongated tubular shaft at the distal-most end of the elongated tubular shaft to define a tube head, the expandable member comprising a balloon; wherein the expandable member includes a proximal neck and a distal neck, the proximal neck having a first thickness and being connected to the elongated tubular shaft proximal to the distal end of the elongated tubular shaft, the proximal portion of the expandable member including a second thickness, the distal portion of the expandable member including a third thickness, and the distal neck inverted and joined to the distal end of the elongated tubular shaft including a fourth thickness; in, As the expandable member expands, it applies tension to the distal end of the elongated tubular shaft, wherein the distal end of the elongated tubular shaft has a lower bending stiffness than the catheter section of the elongated tubular shaft located proximal to the distal end, so that the distal end of the elongated tubular shaft opens and expands into a funnel shape under the tension.

2. A clot capture catheter according to claim 1, wherein the middle portion of the expandable member includes a variable thickness that gradually decreases from the second thickness to the third thickness.

3. The clot capture catheter of claim 1, wherein the first thickness is greater than the second thickness, and the second thickness is greater than the third thickness.

4. The clot capture catheter of any one of claims 1 to 3, wherein the fourth thickness is greater than the third thickness.

5. The clot capture catheter of any one of claims 1 to 3, wherein the fourth thickness is greater than the first thickness.

6. The clot capture catheter of any one of claims 1 to 3, wherein the first thickness is the same as the second thickness in a deflated state, but is greater than the second thickness in an inflated state.

7. A clot capture catheter according to any one of claims 1 to 3, wherein a band is provided between the proximal portion and the distal portion of the expandable member, the band having a wall thickness greater than the wall thickness of the proximal portion and / or the distal portion to form a relatively non-expandable area, so that the expandable member is preferentially inflated proximally and distally of the band to provide a funnel-shaped cross-section.

8. The clot capture catheter of any one of claims 1 to 3, wherein at least one of the proximal portion and the distal portion is reinforced to limit expansion of the portion.

9. The clot capture catheter of claim 8, wherein the proximal portion includes a reinforcement.

10. The clot capture catheter of claim 9, wherein the reinforcement comprises ribs.

11. The clot capture catheter of claim 10, wherein the ribs extend axially and / or radially along at least a portion of the proximal portion.

12. The clot capture catheter of claim 10 or 11, wherein the material of the ribs is the same as or different from the material of the balloon.

13. The clot capture catheter of any one of claims 1 to 3, wherein in the expanded configuration, the cross-section of the distal tip of the expandable member is a non-uniform shape.

14. The clot capture catheter of claim 13, wherein the cross-section comprises an ellipse.

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