Neurovascular catheters and methods of use

Abstract

An improved catheter is provided for removing obstructions from blood vessels, e.g., retrieving clots / thrombi in the neurovasculature for the treatment of stroke. The catheter has a collapsed state that is small and flexible enough for easier delivery through challenging vasculature, and an expanded state that is sized and robust enough to remove obstructions. The catheter may include a self-collapse and expansion mechanism for transitioning a portion of the outer tube (e.g., the braided portion) between the collapsed and expanded states. Such a mechanism may include an inner actuator tube that is slidable over the actuation wire to collapse a distal branch section of the actuation wire, thereby collapsing the braided portion. The catheter may also include an intermediate coiled tube to reinforce the braided portion in the expanded state.

Description

[Technical field]

[0001] I. CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 267,032, filed January 21, 2022, the entire contents of which are incorporated herein by reference.

[0002] (II. TECHNOLOGY FIELD) The present technology relates generally to catheter systems for removing obstructions from blood vessels, for example, retrieving clots / thrombi within the neurovasculature for the treatment of stroke. [Background technology]

[0003] (III. Background) Ischemic stroke is caused by a partial or complete interruption to cerebral blood perfusion. Such interruption can be caused by a thrombus or an embolus, i.e., a blood clot originating from a more proximal location in the bloodstream that becomes trapped in a narrowing intracranial vessel. Interruption of blood flow to a portion of the brain for any extended period of time results in an area of ​​infarcted tissue, known as a core infarct, that is irreversibly damaged and grows larger over time. The infarcted area of ​​the brain will result in neurological deficits that can range from mild speech and coordination problems to a total loss of muscle and cognitive control.

[0004] The oxygen-deprived area surrounding the core infarct also grows larger and the disruption lasts longer. This area, known as the penumbra, can regenerate if blood perfusion is restored in a timely manner. This phenomenon of treatable ischemic events has given rise to the phrase "time is brain," now common among associated clinicians.

[0005] In recent years, techniques for mechanical removal of such blockages have allowed for reperfusion of blood flow and effective treatment of stroke in some cases. Recently, the first of several clinical studies were published that demonstrated the effectiveness of stent retrievers for restoring blood flow versus the standard treatment at the time, which was intravenous thrombolytic agents and aspiration clot retrieval.

[0006] Mechanical clot retrieval devices are generally metal baskets or stents connected to a retrieval wire. During a clot removal procedure, a guidewire is placed across the length of the clot and a catheter is passed over the guidewire to cross the clot. The clot retrieval device is delivered to the required location through the catheter. The catheter or sheath is retracted from over the clot retrieval device, which then expands and engages the clot. The clot retrieval device and the clot integrated therein can then be removed through the vessel using tension by withdrawing the retrieval wire. Optionally, a suction catheter can be used to aid in the removal.

[0007] In many cases, the clot cannot be removed intact during the first pass of the clot retrieval device, and multiple passes are required to obtain restoration of blood flow. Improvement of first pass clot removal is the target of many current developments in the art.

[0008] In practice, clinicians will use a number of different devices to remove clots during endovascular procedures. Generally, a guidewire will be placed into the femoral artery using a modified Seldinger technique and threaded through the carotid artery and into the cerebral vasculature of the brain.

[0009] The guidewire is then pushed through the clot. Once the guidewire is in place, a very narrow tubular catheter known as a microcatheter (approximately 0.4 mm diameter) is advanced over the wire to the distal side of the clot.

[0010] The guidewire is then removed and a stent retriever is pushed through the microcatheter and deployed along the length of the clot. The stent retriever engages the clot and is then retracted to remove the clot from the patient's circulatory system. In most cases, as the procedure is performed, suction is simultaneously applied through a larger diameter catheter that is passed over the microcatheter in close proximity to the clot. The aspiration catheter is stiffer than the microcatheter due to its larger diameter and the reinforcement required to prevent collapse during aspiration. The microcatheter is therefore also required as a support and guide for the introduction of the aspiration catheter through the vasculature.

[0011] European Patent Application No. EP 3718492 A1 discloses a catheter device for removal of blood clots from a patient's circulatory system in which multiple clot engaging elements are deployable independently of each other. In this way, first pass clot removal rates can be improved.

[0012] In addition to the techniques mentioned above, there are several different approaches described using a combination of a stent retriever and an aspiration catheter. Some of these techniques describe complete withdrawal of the stent retriever and clot into the aspiration catheter. Other approaches are directed to the withdrawal of the clot and stent retriever using an aspiration catheter, where the proximal portion of the clot is attached to the aspiration catheter during removal.

[0013] The clot retrieval approach chosen is often influenced by the clot composition; in some cases where the clot is a very soft thrombus, an aspiration catheter alone may be sufficient to remove the entire clot via suction. In this case, a microcatheter may still be required to assist in aiding in navigation of the aspiration catheter to the desired site.

[0014] Regardless of the specific technique used, removal of the clot without delay is crucial. Guidewires and microcatheters are generally advanced quickly to the clot, but positioning of the aspiration catheter can be a limiting factor. The process of advancing the aspiration catheter becomes difficult, especially after passing through the internal carotid artery. This is due to the narrow and tortuous vessels from this point onwards in the cerebral vasculature, and is exacerbated in older patients with diseased and elongated vasculature. This time-consuming portion of the procedure can affect the patient's clinical outcome. In cases where the clot is not removed during the first pass, the cumulative time taken between multiple attempts can be significant.

[0015] Devices with a distally expanding funnel at the distal end of the aspiration catheter have been described. These devices are generally separate from the aspiration catheter, attached through the lumen, and pushed out and expanded from the distal end of the aspiration catheter. Such devices are intended to widen the already large lumen diameter of the aspiration catheter, entangle the stent retriever for removal and / or the clot, and ensure that no microemboli are released during clot removal. WO 02 / 087677 A2 (Patent Document 2), U.S. Patent Application Publication Nos. 2017 / 0303949 and WO 2016 / 113047 A1 to Ribo Jacobi, U.S. Patent Application Publication No. 2019 / 0269491 to Jalgaonkar, and U.S. Patent Application Publication No. 2017 / 0333060 to Panian are examples of documents that are directed to this type of technique.

[0016] No. 6,632,236 to Hogendijk describes an apparatus for embolizing a vessel and enhancing blood flow within a catheter. The catheter includes a multi-section self-expanding woven wire forming a radially expandable body and an embolization distal section, coated with an elastomeric polymer coating and disposed within an outer sheath.

[0017] U.S. Patent No. 6,929,634 to Dorros describes an apparatus and method for the treatment of stroke using a catheter with a distal embolic member in the common carotid artery of the hemisphere of the cerebral embolus. Retrograde flow is provided through the catheter to effectively control the cerebral flow characteristics. Under such controlled flow conditions, a thrombus removal device is used to treat the embolus, and any emboli generated are directed into the catheter.

[0018] Parodi, U.S. Patent No. 6,206,868, discloses an obturation element with a self-expanding wire mesh basket coated with an elastomeric polymer coating. A catheter is first surrounded by a movable sheath and transluminally inserted with the sheath to a distal-most position. The sheath is retracted proximally, deploying the basket, which is again collapsed within the sheath by moving the sheath to its distal-most position.

[0019] U.S. Patent Application Publication No. 2017 / 0238951 to Yang describes a neurovascular catheter for distal neurovascular access or aspiration. The catheter includes an elongated flexible tubular body having a proximal end, a distal end, and a sidewall that defines a central lumen. The distal section of the tubular body includes a tubular inner liner, a tie layer separated from the lumen by the inner liner, a helical coil surrounding the tie layer, an outer jacket surrounding the helical coil, and an opening at the distal end. Adjacent windings of the helical coil are spaced progressively further apart in the distal direction. The opening at the distal end of the tubular body is expandable from a first inner diameter for transluminal passage to a second, larger inner diameter for facilitating aspiration of thrombus into the lumen.

[0020] U.S. Patent Application Publication No. 2017 / 0143938 to Ogle describes a suction catheter system described with a suction nozzle that may extend from a guide catheter of the equivalent. The suction nozzle can be positioned by tracking the suction nozzle through the vessel while moving a proximal portion of the suction extension within the lumen of the guide catheter. The suction lumen extends from the proximal end of the guide catheter, through at least a portion of the guide catheter central lumen, and through the suction tip.

[0021] Vale's U.S. Patent Application Publication No. 2016 / 0256180 describes a rapid exchange (RX) catheter that provides a proximal seal against the guide catheter inner lumen so that suction can be applied through the guide catheter. The catheter may include an exit port that defines a transfer port for suction and may allow minimal frictional engagement with the guide catheter proximal to the exit port. Suction can be applied to the lumen of the guide catheter and directed to and effective at the tip of the RX aspiration catheter. The tip of the RX catheter may expand under load to facilitate aspiration and retrieval of clots and may partially or completely occlude the vessel.

[0022] WO 2017 / 097616 A1 discloses several devices and methods for removing obstructions from blood vessels. A stent retriever is first deployed via a microcatheter, and an aspiration catheter is then advanced to the location of the clot to improve the clot removal process. A clot acceptor device is deployed that seals circumferentially against the distal section of the aspiration catheter so that the stent retriever and clot can be aspirated through a tapered opening of the acceptor device during the removal process. The stent retriever may also be deployed using a microcatheter, and an aspiration catheter is then advanced to the location of the clot to aspirate the stent retriever and clot.

[0023] No. 8,425,549 to Lenker discloses a catheter having a distal portion that can be radially expanded with a coil or helical ribbon that is distally displaceable within the catheter. The expanded configuration allows for the application of negative pressure through the lumen of the catheter to aspirate occlusive material into the lumen through the distal end opening of the catheter.

[0024] Further devices for intraluminal neurovascular intervention of the type shown are disclosed in WO 2016 / 126974, WO 2018 / 169959, and WO 98 / 23320.

[0025] In addition to the catheter devices described above, introducer sheaths are known, which are short cannula-like devices used for vascular access. They are inserted percutaneously into the target vessel and a central dilator is then removed, allowing access for the insertion of guidewires and other devices such as catheters. Recently, several introducer devices have been developed that have the ability to expand and accommodate devices larger than the nominal vessel size. An example of an expandable sheath type device is the Edwards eSheath. TM and Terumo Solopath TM It is.

[0026] In light of the foregoing, there is a need for a catheter that is sufficiently small and flexible to allow navigation through small and / or tortuous vessels (e.g., neurovasculature) while being sufficiently robust to remove obstructions such as blood clots / thrombi. WO 2021 / 1151969 (the entire contents of which are incorporated herein by reference) describes improved catheters for neurovascular endoluminal intervention, e.g., for the treatment of ischemic stroke, that overcome many of the aforementioned shortcomings. It would be beneficial to provide an improved design for easily expanding catheters for obstruction removal and collapsing such catheters for delivery and removal within the vasculature. [Prior art documents] [Patent documents]

[0027] [Patent Document 1] European Patent Application Publication No. 3718492 [Patent Document 2] International Publication No. 2002 / 087677 [Patent Document 3] U.S. Patent No. 6,632,236 [Patent Document 4] U.S. Patent No. 6,929,634 Summary of the Invention [Means for solving the problem]

[0028] (IV. Overview) Provided herein are systems and methods for removing obstructions from blood vessels. Improved catheters are provided that are sufficiently robust to remove obstructions such as clots / thrombi (e.g., via aspiration through the catheter) while being small and flexible enough to allow navigation through small and / or tortuous vessels (e.g., neurovasculature). The catheters are designed to be easily expandable for obstruction removal and collapsible for delivery and removal within the vasculature.

[0029] According to some aspects, a catheter is provided for removing an obstruction from a blood vessel. The catheter may include an elongate tube, an actuator tube disposed within the elongate tube, and an actuation wire disposed within the actuator tube. The elongate tube may be transitionable between an expanded state and a collapsed state. For example, the elongate tube may be sized and shaped to be advanced through the blood vessel to the obstruction in the collapsed state. The actuation wire may include an elongate shaft coupled to a plurality of struts via an articulation region. A distal end of each one of the plurality of struts may be affixed about an outer periphery of the distal end of the elongate tube. The actuator tube and actuation wire may be used to transition the elongate tube between the collapsed state and the expanded state. For example, translation of the actuator tube relative to the actuation wire may cause the plurality of struts to expand radially outward and transition the elongate tube to the expanded state, thereby enabling removal of the obstruction from the blood vessel.

[0030] The elongate tube may include a braided material, which may have an expandable biocompatible coating (e.g., elastomer). The elongate tube may be collapsible via a longitudinal force at a distal end of the elongate tube such that the elongate tube is longer in the collapsed state than in the expanded state.

[0031] The catheter may include an intermediate tube slidably positioned between the elongate tube and the actuator tube. A distal portion of the intermediate tube may be advanced distally within the elongate tube to reinforce the elongate tube for removal of the obstruction. A distal region of the intermediate tube may include a metal coil, which may have a biocompatible coating.

[0032] The catheter may include a vacuum source for applying suction within the elongated tube to draw occluding material into the elongated tube while in the expanded state and remove the occluding material from the blood vessel. For example, the vacuum source may be coupled to the intermediate tube, which is disposed within the elongated tube during application of suction such that occluding material is drawn into the lumen of the intermediate tube.

[0033] The actuator tube and actuation wire may maintain the elongated tube in a collapsed state during delivery and transition the elongated tube from the expanded state to the collapsed state following removal of an obstruction from the blood vessel such that the catheter system can be removed from the subject in the collapsed state. Each strut of the multiple struts may have a curvature to promote uniform collapse of the actuation wire. In some embodiments, the curvature ensures that the distance from the distal tip of each strut to the apex of the actuation wire proximal to the multiple struts is the same. The articulation region of the actuation wire may include a branched structure. Each strut of the multiple struts may include an aperture at its distal tip for coupling to the elongated tube. The elongated wire may be offset from a central longitudinal axis of the elongated tube in the expanded state. The distal ends of the multiple struts may be equidistantly spaced about the circumference of the distal end of the elongated tube. The actuation wire may be formed from Nitinol.

[0034] The actuator tube may be a dual lumen microcatheter having a guidewire lumen configured to receive a guidewire, the guidewire lumen may extend distally from the actuation lumen for the actuation wire within the actuator tube.

[0035] The distal end of the catheter may be sized and shaped to be tunneled to a blood vessel in the brain, for example, the distal end of the catheter may be sized and shaped to be tunneled to the middle cerebral artery in the brain.

[0036] According to some aspects, a method is provided for removing an obstruction from a blood vessel using a catheter. The method may include advancing a distal end of the elongated tube in a collapsed state through the blood vessel to the obstruction while the actuator tube is disposed within the elongated tube, translating the actuator tube relative to an actuation wire to expand a plurality of struts of the actuation wire radially outwardly and transition the elongated tube to an expanded state within the blood vessel, a distal end of each one of the plurality of struts being affixed about an outer periphery of the distal end of the elongated tube, and removing the obstruction from the blood vessel using the elongated tube while in the expanded state. The method may include translating the actuator tube relative to the actuation wire to collapse a plurality of struts of the actuation wire radially inwardly and transition the elongated tube to a collapsed state within the blood vessel. The method may include translating the intermediate tube into the lumen of the elongated tube (e.g., after the actuator tube is removed from the elongated tube) such that the intermediate tube moves into the expanded distal region of the elongated tube and reinforces the distal region for obstruction removal (e.g., via suction). [Brief description of the drawings]

[0037] V. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features, and advantages of the description set forth herein will be apparent from the following description of specific embodiments of those inventive concepts, as illustrated in the accompanying drawings. It should be noted that the drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the inventive concepts. Also, in the drawings, like reference characters may refer to the same or similar parts throughout the different views. It is intended that the embodiments and figures disclosed herein should be considered illustrative, and not limiting.

[0038] [Figure 1A] FIG. 1A shows exemplary components of a catheter for removing obstructions from a blood vessel.

[0039] [Figure 1B] 1B and 1C show the catheter in a collapsed and expanded state, respectively. [Figure 1C] 1B and 1C show the catheter in a collapsed and expanded state, respectively.

[0040] [Diagram 2] FIG. 2A shows a distal region of an elongated tube of a catheter for an exemplary embodiment having a collapsible and expandable braided section that uses a self-collapse / expansion mechanism. FIG. 2B shows the distal region of an exemplary mechanism for self-collapse / expanding the distal region of the elongated tube (e.g., the braided section). FIG. 2C and 2D are perspective views of the exemplary mechanism of FIG. 2B.

[0041] [Diagram 3] FIG. 3 shows exemplary steps for self-collapsing a collapsible portion of an elongate tube using an actuator tube and actuation wire system.

[0042] [Figure 4] FIG. 4 shows exemplary steps for self-collapse of a braided section of an exemplary elongated tube using an actuator tube and actuation wire system.

[0043] [Figure 5-1] 5A-5H show steps for transitioning an exemplary catheter between a collapsed state and an expanded state. [Figure 5-2] 5A-5H show steps for transitioning an exemplary catheter between a collapsed state and an expanded state. [Figure 5-3] 5A-5H show steps for transitioning an exemplary catheter between a collapsed state and an expanded state. [Figure 5-4] 5A-5H show steps for transitioning an exemplary catheter between a collapsed state and an expanded state.

[0044] [Figure 6-1] 6A-6F show an exemplary method for removing obstructions from a blood vessel using a catheter described herein. [Figure 6-2]6A-6F show an exemplary method for removing obstructions from a blood vessel using a catheter described herein. [Figure 6-3] 6A-6F show an exemplary method for removing obstructions from a blood vessel using a catheter described herein.

[0045] [Figure 7] 7A-7F show side views of the exemplary method of FIGS. 6A-6F. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] (VI. Detailed Description) Provided herein are systems and methods for removing obstructions from blood vessels. For example, improved catheters may be used for the treatment of ischemic stroke that allow for easier and faster overall removal of blood clots from blood vessels.

[0047] The catheter has a collapsed state in which the distal outer section is adapted to be easily passed through the vascular system, including through small and / or tortuous vessels (e.g., neurovasculature). The catheter can then be preferably reversibly changed to an expanded state, whereby the distal outer section is expanded to a wider diameter, which may be approximately equal to the diameter of the proximal outer section. This approach allows the catheter to be easily and quickly passed to the target site and subsequently dilated to facilitate removal of one or several clots by aspiration. Using this design, clinicians do not waste valuable time passing a large aspiration catheter through tortuous vessels. In addition, the microcatheter and the aspiration catheter may be combined into a single catheter, which also represents a cost savings.

[0048] 1A, an exemplary catheter is shown that may be used to remove obstructions from a blood vessel, for example to treat a stroke. Catheter 100 illustratively includes an elongate tube 200 that is transitionable between an expanded state and a collapsed state. Elongate tube 200 has a proximal region 202, a distal region 204, and a lumen 206 extending therebetween. Elongate tube 200 is sized and shaped to be advanced through the blood vessel to the obstruction in the collapsed state.

[0049] To transition the elongated tube 200 between the collapsed state and the expanded state, an actuation wire 208 is provided. As shown, the actuation wire 208 may include an elongated shaft 210 coupled to a plurality of struts 212 via an articulation region 214. A distal end of each one of the plurality of struts 212 may be affixed about the circumference of the distal end of the elongated tube 200. The actuation wire 208 preferably has a length greater than the elongated tube 200. Thus, the actuation wire 208 may be coupled to the distal end of the elongated tube and extend out from the proximal end, as shown in FIG. 1A, for manipulation by a clinician.

[0050] The portion of the elongate tube 200 at the distal region 204 is preferably formed from a collapsible and expandable material such as a coil, laser cut tube, or braid 216 as shown. The distal region 204 may be coated with an expandable biocompatible material such as an elastomer. For example, the collapsible / expandable portion of the elongate tube 200 may be an elastomer coated braid or coil. The proximal region 202 may be formed from a different material than the distal region 204. For example, the proximal region 202 may include a shaft 218 formed from a polymer, as is known in the art of catheter design. The diameter of the proximal region 202 may be fixed such that only the distal region 204 has a variable diameter. The elastomer coated braid or coil may be bonded to the proximal region 202 via, for example, an adhesive. The extension tube 200 may include a hemostatic valve 220 at its proximal end to allow for the insertion of additional interventional devices into the extension tube's lumen 206 and to block the proximal end of the lumen 206 when the hemostatic valve 220 is closed.

[0051] Preferably, the shaft 218 of the elongate tube 200 is flexible. The distal region 204 (illustratively, the braided portion 216) is flexible to allow navigation through the vascular system, particularly including through small and / or tortuous vessels.

[0052] The catheter 100 may further include an actuator tube 300 that is sized and shaped to be disposed within the elongated tube 200. The actuator tube 300 includes a proximal region 302, a distal region 304, and a lumen 306 extending therebetween. The lumen 306 is sized and shaped to receive an actuation wire 208 therethrough. Preferably, the actuator tube 300 has a length longer than the shaft of the elongated tube 200, while the actuation wire 208 is preferably longer than the actuator tube 300.

[0053] The actuator tube 300 cooperates with the actuation wire 208 to transition the distal region 204 of the elongated tube 200 between a collapsed state and an expanded state. This provides a self-collapse mechanism for easy and repeatable transitions between these states. For example, translation of the actuation wire 208 relative to the actuation tube 300 causes the plurality of struts 212 to expand radially outward, transitioning the elongated tube 200 to the expanded state, thereby enabling removal of obstruction from a blood vessel.

[0054] The actuator tube 300 may function as a microcatheter. The shaft 308 in the proximal region 302 may be relatively rigid, e.g., a hypotube. The diameter of the actuator tube 300 may be fixed such that the actuator tube 300 is not expandable. The distal region 304 is preferably more flexible than the proximal region to allow passage through curved and tortuous vessels. The actuator tube 300 may include a guidewire lumen 310 for receiving a guidewire therethrough. As shown, the actuator tube 300 may be a dual lumen microcatheter having both a guidewire lumen 310 and a lumen 306 for receiving an actuation wire 208 therethrough. The guidewire lumen 310 may extend distally within the shaft than the actuation lumen 306 for the actuation wire 208 within the actuator tube 300.

[0055] Actuator tube 300 may include a hemostatic valve 312 at its proximal end to allow for the insertion of additional interventional devices (e.g., guidewires, actuation wires) into the lumen of actuator tube 300 and may block the proximal ends of lumens 306 and / or 310 when hemostatic valve 312 is closed.

[0056] The catheter 100 may further include an intermediate tube 400 that is sized and shaped to be disposed within the elongate tube 200. The intermediate tube 400 includes a proximal region 402, a distal region 404, and a lumen 406 extending therebetween. The lumen 406 is sized and shaped to receive the actuator tube 300 therethrough. Preferably, the intermediate tube 400 has a length that is less than the actuator tube 300 but longer than the shaft of the elongate tube 200, although the actuation wire 208 is preferably longer than the intermediate tube 400.

[0057] An intermediate tube 200 is slidably disposed within the elongated tube 200. For example, the distal end of the intermediate tube 200 may be positioned proximal to the distal end of the elongated tube 200 during delivery to maintain a low profile of the catheter 200. Once suitable positioning is achieved adjacent to the obstruction in the blood vessel and the elongated tube 200 is transitioned to an expanded state, the intermediate tube 400 may be advanced distally within the elongated tube 200 to reinforce the elongated tube 200 for removal of the obstruction.

[0058] The proximal region 402 may be formed from a different material than the distal region 404. For example, the proximal region 402 may include a shaft 408 formed from a polymer, known in the art of catheter design, to provide flexibility. The distal region 404 may include a coil 410 (e.g., a biocompatible metal such as Nitinol or stainless steel) with a biocompatible coating (e.g., PTFE). The coil 410 may be tightly wound such that adjacent windings within the coil contact one another. The diameter of the intermediate tube 400 may be fixed such that the intermediate tube 400 is not expandable. The intermediate tube 400 may include a hemostatic valve 412 at the proximal end to allow insertion of an additional interventional device (e.g., the actuator tube 300) into the lumen 406 of the intermediate tube 400 and block the proximal end of the lumen 406 when the hemostatic valve 412 is closed. One or more additional valves 414 may be connected to the proximal end of the intermediate catheter 400 to allow for connection to a vacuum source, for example, for aspiration of occlusions within a blood vessel through the catheter 100.

[0059] 1B and 1C, the catheter 100 is shown in a collapsed state and an expanded state, respectively. The actuator tube 300 may be actuated to transition the catheter 100 from the collapsed state to the expanded state and then further actuated to transition the catheter 100 from the expanded state to the collapsed state. The actuator tube 300 may be moved in one direction (e.g., proximally) relative to the actuation wire 208 to actuate the transition from collapsed to expanded, and moved in another direction (e.g., distally) relative to the actuation wire 208 to actuate the transition from expanded to collapsed. For example, the actuator tube 300 may be unlocked and moved proximally by the clinician while the elongate shaft 200 and intermediate tube 400 remain in place to expand the distal region 204 of the elongate shaft (e.g., the braided portion 216). Thus, the elongation tube 200 is collapsible via a longitudinal force at the distal end of the elongation tube 200. As shown, the elongation tube 200 is longer in the collapsed state than in the expanded state.

[0060] In this manner, the braided distal end of the catheter 100 may be collapsed by being stretched. Braid expansion may generally be achieved by applying a longitudinal force to the distal end of the braided section. Conversely, braid expansion may be achieved by releasing the longitudinal force. Advantageously, the distal end of the extension tube 200 may be held in place during expansion to prevent the catheter tip from bouncing back upon release of the force. The self-collapse mechanism allows a force to be applied to the distal end of the braid and hold the distal end in place during expansion. As an additional advantage, these mechanisms allow for the advancement of the actuator tube 300 (e.g., a microcatheter) toward the distal end of the extension tube 200, gradually reducing the diameter of the distal lumen, and using the actuator tube 300 to subsequently stretch the braided section 216 and narrow / collapse the entire distal braided section. Thus, the braid 216 can be collapsed onto the actuator tube 300 to provide microcatheter sizing and flexibility for delivery and removal of the catheter 100.

[0061] The catheter 100 is preferably adapted to be inserted into the femoral artery of an adult human patient and passed to the brain, for example the middle cerebral artery of the patient. Thus, the length of the catheter is preferably such that the catheter extends at least from the femoral artery of an adult human patient to the brain, in particular the middle cerebral artery of the same patient, outside the patient for manipulation at the proximal end by a clinician. Depending on the application (e.g. in animals or humans, in children, in female or male adults, etc.), the catheter 100 preferably has a total length of at least 30 cm, more preferably at least 40 cm. For use in humans, in particular adult humans, the total length of the catheter is preferably in the range of 100 cm to 200 cm, more preferably in the range of 130 cm to 180 cm.

[0062] The sizing of the catheter 100 may be optimized for navigation within the neurovasculature. For example, the outer diameter of the shape-changing distal section (e.g., braided section) of the elongated tube may be 0.5-6 mm in the collapsed state and 1-10 mm in the expanded state. In addition, the length of the shape-changing distal section of the elongated tube may be at least 10 cm from the distal end of the elongated tube 200, such as 10-25 cm in total, and when transitioned to the expanded state may be shortened in length by about 5-25% compared to the collapsed state. In some embodiments, the diameter of the distal region of the actuator tube 300 may be 0.4-2 mm for a dual lumen microcatheter configuration. The outer diameter of the intermediate tube 400 may be 1-10 mm with an inner diameter of 0.8-8 mm. The length of the coiled section of the intermediate tube 400 may extend at least 10 cm from the distal end of the intermediate tube 400.

[0063] 2A, a diagram of an exemplary distal region of an elongate tube 200 is shown. The elongate tube 200 may include a braid 216 at a distal end and a shaft 218 that is proximally coupled by the braid 216. An actuation wire 208 is shown to facilitate self-collapse / expansion of the distal end of the elongate tube 200 (e.g., the entire braided section). In some embodiments, the self-collapse / expansion mechanism (actuation wire 208) is mounted to the distal end of the braided structure and facilitates reduction in braid diameter by allowing the clinician to both collapse the distal braid and expand the braid by applying a force longitudinally to the distal end of the braid.

[0064] 2B shows a distal region of an exemplary mechanism for self-collapse of the distal region of the elongated tube. The actuation wire 208 illustratively includes an elongated shaft 210 coupled to the struts 212 via an articulation region 214. The actuation wire 208 may be formed from a biocompatible metal, such as Nitinol or stainless steel, and may exhibit shape memory properties. In some embodiments, the actuation wire 208 is formed from Nitinol wire. The actuation wire 208 may be formed from Nitinol wire with a distal multi-armed Nitinol as shown. The actuation wire 208 may be formed from a single piece of Nitinol or multiple Nitinol pieces bonded together. For example, the struts 212 may be laser cut from a single Nitinol tube and bonded to the Nitinol wire at the apex 222, e.g., via welding. The struts 212 may be configured to self-expand when actuated, e.g., exposed from the lumen of the actuator tube. Each strut 212 may have a curvature 224 to promote uniform collapse of the actuation wire 208. In some embodiments, the curvature 224 of each strut 212 ensures that the distance from the distal tip 226 of each strut 212 to the apex 222 of the actuation wire 208 is the same. The apex 222 preferably starts proximal to the plurality of struts 212. Each of the struts 212 may have an S-shape. For example, the top strut may form an S-shape with the extension shaft 210 as shown, with one or more additional struts branching off from the top strut in the S-shape configuration. There may be multiple top struts, for example, two as shown in FIG. 2C. In some embodiments, the struts 212 do not create a perfect circle around the circumference at the distal end of the extension tube. For example, there may be gaps between the struts (e.g., the top strut shown in FIG. 2C). As such, articulation region 214 may have a branched structure, and in some embodiments, the branch has multiple branches extending therefrom that form their own distinct network of branches.

[0065] 2C, a perspective view of the distal region of the actuation wire 208 is shown. The struts 212 may be arranged circumferentially to connect to the inner lumen of the elongate tube (e.g., the braid). The elongate shaft 210 may be offset from the central longitudinal axis of the elongate tube in the expanded state. This ensures that the elongate shaft 210 does not occlude the lumen of the elongate tube. Each strut 212 may include a coupling mechanism for coupling to the distal end of the elongate tube. For example, each strut 212 may include an eyelet 228 at its distal tip to facilitate connection to the braid.

[0066] 2D, the distal ends of the struts 212 may be equidistantly spaced such that the struts are spaced about the circumference of the distal end of the extension tube. As shown, there may be six struts, spaced 60 degrees apart from one another.

[0067] FIG. 3 illustrates exemplary steps for self-collapse using an actuation mechanism. For example, as the actuator tube 300 is advanced relative to the actuation wire 208, the actuation wire 208 is retracted into the lumen 306 of the actuator tube 300. This causes the distal multi-armed strut structure to collapse radially inward and transition to the collapsed state. As shown, the curvature of the struts ensures equal circumferential collapse forces. The actuator tube 300 may be advanced distally while the actuation wire 208 is held in place, the actuation wire 208 may be moved proximally while the actuator tube is held in place, or the actuator tube 300 may be advanced distally while the actuation wire 208 is moved proximally.

[0068] FIG. 4 illustrates the step of FIG. 3 in an exemplary embodiment in which the collapsible section of the elongated tube is braided. The actuator tube 300 and actuation wire 208 maintain the elongated tube 200 in a collapsed state during delivery as illustrated in FIG. 4, and may transition the elongated tube 200 from an expanded state to a collapsed state, for example, after removal of an obstruction from a blood vessel, so that the catheter can be removed from the subject in the collapsed state. As the actuator tube 300 (e.g., a microcatheter) is advanced relative to the Nitinol wire, this causes the self-collapse mechanism (e.g., a distal region of the actuation wire 208) to retract into the microcatheter lumen. This causes the distal multi-armed structure to collapse radially inward. When the self-collapse mechanism is fully retracted into the microcatheter lumen, the distal tip of the braid is fully collapsed and the microcatheter is effectively attached to the distal end of the braid. By advancing the microcatheter even further, the braid is stretched and the entire braided structure can be collapsed onto the microcatheter, as shown at the bottom of FIG.

[0069] Also provided herein are methods of using catheter 100. As should be understood, the description of the methods is merely illustrative, the order of steps may be modified, and no step is optional unless expressly described as required.

[0070] 5A-5H show an exemplary method for transitioning the catheter 100 between the collapsed state and the expanded state. For illustrative purposes, the collapsible and expandable distal region of the elongated tube will be described as a braided section. With reference to FIG. 5A, the catheter 100 is shown in a collapsed state for delivery. As shown, the actuator tube 300 is disposed within the lumen of the elongated tube 200 and the distal region of the actuation wire 208 is collapsed within the actuator tube 300. Thus, the actuator tube 300 is fully extended and locked with the expanded / collapsed distal braid ready for delivery (e.g., via one or more hemostatic valves). Additionally, the actuator tube 300 may be disposed within the lumen of an intermediate tube 400, which is disposed within the lumen of the elongated tube 200. However, the distal end of the intermediate tube 400 is positioned proximal to the distal end of the elongated tube 200 such that the braided section of the elongated tube 200 is collapsed onto the actuator tube 300. For example, the distal end of the intermediate tube 400 may be positioned proximal to the braided section of the elongated tube 200 in the delivery state.

[0071] 5B shows the elongated tube 200 transitioned from a collapsed state to an expanded state. For example, the actuator tube 300 may be unlocked (via one or more hemostatic valves) such that the force applied to elongate the distal braid is removed, thus expanding the braid 216. The braid 216 may expand when the struts 212 of the actuation wires 208 are exposed from the distal end of the lumen 306 of the actuator tube 300, causing the struts 212 to self-expand, thereby causing the braid 216 to self-expand.

[0072] 5C, the actuator tube 300 is completely removed, for example, by translating the actuator tube 300 proximally along the actuation wire 208.

[0073] In FIG. 5D, the intermediate tube 400 is translated relative to the elongated tube 200. For example, the intermediate tube 400 may be advanced distally relative to the pushing coil 410 and into the lumen of the collapsible / expandable section (e.g., the braided lumen) of the elongated tube 200 while the elongated tube 200 is in the expanded state. The intermediate tube 400 may be advanced distally to contact the struts 212 as shown. Thus, the struts 212 may stop the distal advancement of the intermediate tube 400 such that the distal end of the intermediate tube does not extend to or beyond the distal end of the elongated tube 200. The intermediate tube 400 preferably reinforces the braid and allows for suction, for example, to suck occlusion material into the catheter 100. For example, a vacuum source 500 may be coupled to the catheter 100 and apply suction into the elongated tube 200 to suck occlusion material into the elongated tube 200 while in the expanded state and remove the occlusion material from the blood vessel. The vacuum source 500 is a device capable of applying suction into the catheter tube to remove obstructions. In some embodiments, the vacuum source 500 is coupled to the intermediate tube 400 (e.g., via one or more valves 414) to apply suction into the lumen of the intermediate tube 400. Thus, obstructions may be sucked into the lumen of the intermediate tube 400 while the intermediate tube 400 is within the lumen of the extension tube 200.

[0074] 5E, the intermediate tube 400 is retracted proximally relative to the distal end of the elongate tube 200. For example, the intermediate tube 400 may be moved proximally to remove the intermediate tube 400 from the lumen of the collapsible / expandable portion of the elongate tube 200 (e.g., from the braided lumen).

[0075] 5F, the actuator tube 300 is repositioned over the actuation wire 208. For example, the actuator tube 300 is advanced distally within the lumen of the extension tube 200 (within the lumen of the intermediate tube 400). The actuator tube 300 may be advanced to the articulating region of the actuation wire 208.

[0076] 5G, the actuator tube 300 is advanced relative to the elongate tube 200 (and intermediate tube 400) to recapture the distal collapse mechanism and narrow the distal braid lumen. For example, the actuator tube 300 may be advanced distally relative to the actuation wire 208 until the struts 212 of the actuation wire 208 collapse, thereby collapsing the distal end of the braid 216.

[0077] In FIG. 5H, the actuator tube 300 is fully advanced, completely collapsing the collapsible section of the elongate tube 200. For example, the struts of the actuation wire 208 may be fully collapsed within the lumen of the actuator tube 300, and the actuator tube 300 advanced distally, reducing the braid diameter and extending the braid length to the collapsed state. The actuator tube 300 may be locked (e.g., via one or more hemostatic valves) in the fully advanced position. The catheter 100 may then be removed from the patient in the collapsed state. Alternatively, the catheter 100 may then be moved to a different location within the blood vessel (or to a different blood vessel) and one or more additional occlusions removed using the methods described herein.

[0078] 6A-6F illustrate an exemplary method for removing an obstruction from a blood vessel using catheter 100. An obstruction within the blood vessel is identified using standard visualization techniques. For example, a patient suffering an ischemic stroke may be determined to have an obstruction O within the M1 segment of the middle cerebral artery MCA, which branches off from the internal carotid artery ICA.

[0079] As shown in Figure 6A, a clinician may thread a guidewire 600 to the target occlusion O. The distal end of the guidewire 600 may cross the occlusion O as shown. The catheter 100 may then be advanced over the guidewire 600 until the distal tip of the catheter 100 is positioned within a desired location within the blood vessel, such as directly adjacent the occlusion O, as shown in Figure 6B. In some embodiments, the guidewire 600 is advanced through a guidewire lumen in the actuator tube 300 of the catheter 100.

[0080] The guidewire may then be removed from the catheter 100, and thereby from the patient, as shown in FIG. 6C.

[0081] Then, as shown in FIG. 6D , while the clinician holds the distal tip of the catheter 100 in place (e.g., by holding the proximal end of the actuation wire), the actuator tube 300 is unlocked (e.g., by unlocking the hemostatic valve), expanding the distal braided portion 216 of the elongated tube 200. For example, the actuator tube 300 may be translated relative to the actuation wire 208, causing the struts of the actuation wire 208 to expand radially outward and transition the elongated tube 200 to an expanded state within the blood vessel. In some embodiments, the actuator tube 300 may be moved proximally relative to the actuation wire such that an expandable distal portion of the actuation wire is exposed from the lumen of the actuator tube and expands, thereby expanding the braided portion. The actuator tube may then be removed from the patient.

[0082] 6E, the intermediate tube 400 is advanced distally relative to the elongate tube 200 such that the coiled portion of the intermediate tube is disposed within the braided lumen and reinforces the distal catheter shaft. Suction may then be applied into the lumen of the catheter 100 such that occlusion material is aspirated into the lumen of the catheter 100, as shown in FIG. 6F. The catheter may then be transitioned from the expanded state to the collapsed state, as described above with respect to FIGS. 5E-5H, such that the catheter may be removed from the patient in the collapsed state or moved elsewhere. For example, the actuator tube 300 may be translated relative to the actuation wire 208 to collapse the struts of the actuation wire 208 radially inwardly and transition the elongate tube 200 to the collapsed state within the blood vessel for repositioning / removal.

[0083] 7A-7F show side views of the exemplary method of FIGS. 6A-6F for added clarity.

[0084] While various illustrative embodiments of the present invention are described above, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the invention. It is intended that the appended claims cover all such changes and modifications that fall within the true spirit and scope of the present invention.

Claims

1. 1. A catheter for removing an obstruction from a blood vessel, the catheter comprising: an elongate tube having a lumen and a distal end, the elongate tube configured to transition between an expanded state and a collapsed state, the elongate tube sized and shaped to be advanced through the blood vessel to the occlusion in the collapsed state; an actuator tube disposed within the elongation tube; an actuation wire disposed within the actuator tube, the actuation wire including an elongated shaft coupled to a plurality of struts via an articulation region, a distal end of each one of the plurality of struts being affixed about a circumference of the distal end of the elongated tube; Equipped with A catheter in which translation of the actuator tube relative to the actuation wire causes the plurality of struts to expand radially outward and transition the elongate tube to the expanded state, thereby enabling removal of the obstruction from the blood vessel.

2. The catheter of claim 1 , wherein the elongate tube comprises a braided material having an expandable biocompatible coating.

3. The catheter of claim 1 or 2, wherein the elongate tube is collapsible via a longitudinal force at a distal end of the elongate tube such that the elongate tube is longer in the collapsed state than in the expanded state.

4. 10. The catheter of any preceding claim, further comprising an intermediate tube configured to be positioned between the elongate tube and the actuator tube, a distal portion of the intermediate tube configured to be advanced distally within the elongate tube to reinforce the elongate tube for removal of the occlusion.

5. The catheter of claim 4 , wherein a distal region of the intermediate tube comprises a metal coil having a biocompatible coating.

6. 10. The catheter of any preceding claim, further comprising a vacuum source configured to apply suction within the elongated tube to draw the occlusion material into the elongated tube while in the expanded state and remove the occlusion material from the blood vessel.

7. A catheter as described in any preceding claim, wherein the actuator tube and the actuation wire maintain the elongated tube in the collapsed state during delivery and transition the elongated tube from the expanded state to the collapsed state after removal of the obstruction from the blood vessel such that the catheter system is removable from a subject in the collapsed state.

8. 2. A catheter according to any preceding claim, wherein each strut of the plurality of struts has a curvature to promote uniform collapse of the operating wire.

9. The catheter of claim 8 , wherein the curvature ensures that the distance from a distal tip of each strut to a vertex of the operating wire proximal to the plurality of struts is the same.

10. 2. A catheter according to any preceding claim, wherein the articulation region comprises a branched structure.

11. 2. A catheter according to any preceding claim, wherein each strut of the plurality of struts comprises an aperture at a distal tip for connection to the elongate tube.

12. 2. The catheter of claim 1, wherein the elongate wire is offset from a central longitudinal axis of the elongate tube in the expanded state.

13. 2. The catheter of any preceding claim, wherein the distal ends of the plurality of struts are equidistantly spaced about the circumference of the distal end of the elongate tube.

14. 2. The catheter of any preceding claim, wherein the operating wire is formed from Nitinol.

15. 10. The catheter of any preceding claim, wherein the actuator tube comprises a dual lumen microcatheter having a guidewire lumen configured to receive a guidewire.

16. The catheter of claim 15 , wherein the guidewire lumen extends distally from an actuation lumen for the actuation wire within the actuator tube.

17. 2. A catheter according to any preceding claim, wherein the distal end of the catheter is sized and shaped to be tunneled to the blood vessel in the brain.

18. 20. The catheter of claim 17, wherein the distal end of the catheter is sized and shaped to be tunneled to the middle cerebral artery in the brain.

19. 1. A method for removing an obstruction from a blood vessel using a catheter, the method comprising: advancing a distal end of the elongate tube in a collapsed state through a blood vessel to the occlusion while an actuator tube is disposed within the elongate tube; translating an actuator tube relative to an actuation wire to radially expand struts of the actuation wire outwardly and transition the elongate tube to an expanded state within the vessel, a distal end of each one of the struts being affixed about a circumference of the distal end of the elongate tube; removing the obstruction from the blood vessel using the elongated tube while in the expanded state; A method comprising:

20. 20. The method of claim 19, further comprising translating the actuator tube relative to the actuation wire to cause the plurality of struts of the actuation wire to radially inwardly collapse and transition the elongate tube to the collapsed state within the blood vessel.

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