Devices, systems, and methods for clot detection and removal

Abstract

Methods, apparatuses and systems for monitoring, including electrically and optically monitoring an aspiration catheter to identify material in proximity to or within the catheter. In particular, described herein are methods and apparatuses that may be used to identify clot material, and to distinguish clot material from blood and / or vessel wall. Also described herein are methods and apparatuses for sizing vessels and identifying side vessels.

Description

DEVICES, SYSTEMS, AND METHODS FOR CLOT DETECTION AND REMOVALCLAIM OF PRIORITY

[0001] This patent application claims priority to U.S. provisional patent application no. 63 / 663,039, titled “DEVICES, SYSTEMS, AND METHODS FOR CLOT DETECTION AND REMOVAL,” and filed on June 21, 2024, herein incorporated by reference in its entirety.INCORPORATION BY REFERENCE

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.BACKGROUND

[0003] Blockage of blood vessels may result in serious medical and health issues. For example, a thromboembolism is characteristic of numerous common, life-threatening conditions. Examples of potentially fatal diseases resulting from thrombotic occlusion include pulmonary embolism, deep vein thrombosis, and acute limb ischemia. Acute pulmonary embolism is a significant cause of death in the United States. Pulmonary embolism can be a complication from deep vein thrombosis, which has an annual incidence of 1% in patients 60 years and older. All of the aforementioned diseases are examples of conditions in which treatment may include aspiration or evacuation of clot using a vacuum- assisted thrombectomy procedure.

[0004] However, vacuum-assisted thrombectomy procedures must sometimes be terminated due to the risk of excessive blood loss by the patient, especially when using large aspiration catheters. During aspiration thrombectomy, prior to contacting the clot material and / or when the catheter tip falls out of contact with the clot material (e.g., thrombus or other occlusive material), the tip is exposed to healthy blood and may remove blood at full flow and the blood loss rate may be excessive. In addition the tip may contact and adhere to the vessel wall, referred to as latching, which may be difficult to distinguish from clot. These problems may be exacerbated where clot is hard and difficult to remove.

[0005] It may also be difficult to determine when clot has been taken into the lumen of the aspiration apparatus, including when the aspiration apparatus is clogged. It would also be very helpful to accurately and / or quantitatively determine how much clot has been removed.

[0006] It would therefore be desirable to provide methods and apparatuses (e.g., systems, devices, etc.) for detecting thrombus using a catheter. It would be particularly useful to provide apparatus and methods for automatically sensing clot (thrombus) to assist in removal of clot material as well as apparatus and methods for detecting wall latch upon aspiration. The methods and apparatuses described herein may address these issues.SUMMARY OF THE DISCLOSURE

[0007] Described herein are methods and apparatuses for sensing clot material using one or more sensing electrodes. These methods and apparatuses may include sensing electrodes that may be present on tools for insertion and manipulation within a blood vessel, and / or on one or more tools or apparatuses (e.g., devices, systems, etc.) that may be inserted or implanted within he body. For example, described herein are devices including one or more sensing electrodes for sensing, detecting, and / or characterizing clot material based on impedance or the combination of impedance and another modality. The devices may include, but are not limited to catheters, funnels, occluder, obturators, baskets, etc. Also described herein are methods and apparatuses for refining the sensed impedance signal, including determining a differential impedance signal, signal filtering, signal amplification, or the like. These systems may include a monopolar sensing electrode and / or a bipolar sensing electrode.

[0008] For example, described herein are systems for detecting a clot in a blood vessel, comprising: a catheter comprising a first monopolar electrode and a second monopolar electrode, the catheter configured for insertion into a blood vessel; a reference electrode; a non-transitory computer readable storage medium storing a set of instructions capable of being executed by a processor, wherein the set of instructions, when executed by the processor, causes the processor to: obtain a first impedance signal from the first monopolar electrode; obtain a second impedance signal from the second monopolar electrode; subtract the second impedance signal from the first impedance signal to forma differential impedance signal; and determine from the differential impedance signal if the first electrode is in proximity to a clot material.

[0009] In any of these examples, the first and second monopolar electrodes may be positioned at different locations along a distal end region of the catheter. The reference electrode may comprise a large-area (e.g., greater than 1 cm2, greater than 5 cm2, greater than 15 cm2, greater than 25 cm2, greater than 50 cm2, greater than 100 cm2, etc.) patch electrode configured to be placed on the skin of a subject. The processor may be further configured to filter the differential impedance signal to remove noise artifacts caused by respiration, heartbeat, or patient motion.

[0010] In any of these apparatuses, the catheter may further comprise a third monopolar electrode configured to serve as a noise-removal electrode. In some cases, the processor may be further configured to determine a type of clot material based on the magnitude or phase of the differential impedance signal. The catheter may comprise a distal aspiration opening and the first monopolar electrode is positioned adjacent to the aspiration opening.

[0011] The processor may be further configured to control an aspiration mechanism based on the determination of clot proximity. In some examples, the catheter includes a conductive braid or hypotube forming at least part of the reference electrode. The processor may be further configured to compare the differential impedance signal to a threshold value to determine the presence of clot material.

[0012] In some examples the catheter is further configured to transmit a signal between 10 MHz and 10 GHz for radiofrequency impedance sensing.

[0013] For example, described herein are clot aspiration catheters, comprising: a monopolar electrode at a distal end region, wherein a first conductive wire or trace connects the monopolar electrode with a proximal end region of the catheter; and a reference electrode along an outer length of the catheter, wherein a second conductive wire or trace connects the monopolar electrode with the proximal end of the catheter; wherein the monopolar electrode and reference electrode are configured to cooperate to provide an impedance value to a microprocessor. The reference electrode may comprise a conductive braid or coil embedded in the catheter wall. In some cases the monopolar electrode is a ring electrode positioned adjacent to a distal aspiration opening. In any of these catheters the reference electrode may be a hypotube extending along a proximal portion of the catheter. The microprocessor may be configured to filter the impedance value to remove physiological noise.

[0014] Also described herein are methods for detecting a blood clot in a vessel, the method comprising: inserting a catheter having one or more electrodes at a distal end region into a blood vessel, wherein each of the one or more electrodes is in electrical communication with a signal generator; transmitting, from the signal generator, a signal between 10Hz - 10GHz; transmitting, from each of the one or more electrodes, a transmitted signal from each of the one or more electrodes; detecting a magnitude and phase shift in the transmitted signal, wherein the presence of the phase shift is indicative of blood clot near the one or more electrodes. In any of these methods, the signal may be transmitted at a frequency between 100 MHz and 1 GHz. Any of these methods may include comparing the detected phase shift to a reference signal to determine clot presence. The one or more electrodes may be configured as radiofrequency antennas.

[0015] Also described herein are methods for extracting a clot from a blood vessel, the method comprising: detecting an impedance signal from one or more electrodes at a distal end region of a catheter; identifying, based on the impedance signal, that a clot is adjacent to the one or more electrodes and what type of clot is adjacent to the one or more electrodes by comparing the impedance signal to a threshold value; controlling the application of aspiration through the catheter based on determined type of clot. The type of clot may be determined as acute or chronic based on the impedance signal. In any of these methods, aspiration may be initiated only if the impedance signal indicates an acute clot. The catheter may further comprise a controller configured to adjust aspiration strength based on clot type.

[0016] Also described herein are embolic filter devices that include: an embolic filter basket comprising a mesh configured to capture clots and to allow blood to pass through; one or more bipolar electrode pairs configured to sense impedance on the filter basket; and a controller configured to receive an impedance signal from the one or more bipolar electrode pairs to determine the presence of clot material within the embolic filter basket. The mesh may comprise a plurality of conductive strands forming the bipolar electrode pairs. The controller may be configured to wirelessly transmit clot detection data to an external receiver. The impedance signal may be used to estimate the volume of clot captured in the filter basket.

[0017] Also described herein are methods of removing a clot from a blood vessel in a subject, the method comprising: advancing a catheter and an obturator extending distally from the catheter through the blood vessel; sensing an impedance signal from one or more electrodes on an outer surface of the obturator extending distally from the catheter; determining that the distal end of the obturator is adjacent to a clot material based on the impedance signal; removing the obturator from the catheter while leaving the catheter in place; and aspirating through the catheter to remove the clot material from the blood vessel. The obturator may comprise a conical tip with multiple sensing electrodes along its slant height. Any of these methods may include determining the distance between the clot and the catheter tip based on electrode position. The catheter may be configured to aspirate only after the obturator is withdrawn.

[0018] Also described herein are methods of forming an aspiration catheter having one or more sensing electrodes, any of these method may include: forming a first electrode at a distal end region of the aspiration catheter and forming conductive trace electrically coupling the first electrode to a proximal electrode pad; applying a non-conductive layer over the catheter body to electrically insulate the conductive trace; applying an outer jacket over the non-conductive layer of the catheter body; and forming a ring electrode at a proximal endregion of catheter body, so that the ring electrode is in electrical communication with the proximal electrode pad. The conductive trace may be formed by printing a conductive ink on the catheter body. The non-conductive layer may comprise a polyether block amide material. The ring electrode may be formed by exposing a conductive pad embedded within the catheter wall.

[0019] An aspiration catheter device having a distal funnel region may include: a catheter body; a distal funnel coupled to the catheter body; one or more sensing electrodes on the distal funnel; and a controller configured to receive an impedance signal from the one or more sensing electrodes to determine the presence of clot material within the distal funnel. The distal funnel may be collapsible and self-expanding. The sensing electrodes may be positioned on an inner surface of the funnel. The controller is configured to adjust funnel deployment based on detected clot presence.

[0020] Also described herein are systems for capturing clot from a blood vessel in a subject that include: a catheter configured for insertion into the blood vessel; a plurality of expandable tines at the distal end region of the catheter; one or more sensing electrode on each of the plurality of expandable tines; a controller configured to receive an impedance signal from the one or more sensing electrodes to determine the presence of clot material adjacent to the tines. The expandable tines may be configured to form a reverse umbrella shape. The sensing electrodes may be configured to detect clot in side branches of the blood vessel. The controller may be configured to generate a visual or auditory alert upon clot detection.

[0021] A clot sensing device may include: an elongate body; an expandable member at a distal end of the elongate body; one or more sensing electrodes on the expandable member; a proximal handle comprising a control input configured to controllable expand or collapse the expandable member; a proximal output configured to indicate when the one or more sensing electrodes are in contact with clot. The expandable member may comprise a plurality of splines with embedded electrodes. The proximal output may comprise a visual indicator that changes color based on clot detection. The control input may be configured to rotate the expandable member to assist in clot removal.

[0022] All of the methods and apparatuses described herein, in any combination, are herein contemplated and can be used to achieve the benefits as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] A better understanding of the features and advantages of the methods and apparatuses described herein will be obtained by reference to the following detaileddescription that sets forth illustrative embodiments, and the accompanying drawings of which:

[0024] FIG. 1 A is a schematic diagram of a patient showing an aspiration catheter with sensing electrode and a large reference electrode.

[0025] FIG. IB is a graph of an example of impedance measured using monopolar electrodes before and after filtering.

[0026] FIG. 1C is a schematic illustration of the contribution to impedance of a small monopolar electrode vs. a large reference electrode.

[0027] FIG. ID is an illustration of catheter monopolar electrode arrangement.

[0028] FIG. IE is an illustration of another catheter monopolar electrode arrangement.

[0029] FIG. IF is an illustration of another catheter monopolar electrode arrangement.

[0030] FIG. 1G is an illustration of another catheter monopolar electrode arrangement.

[0031] FIG. 1H is a flowchart illustrating steps for impedance filtering.

[0032] FIG. 2A is an illustration of a catheter with an exposed braid / coil as a reference electrode.

[0033] FIG. 2B is an illustration of a catheter with a hypotube as a reference electrode.

[0034] FIG. 2C is an illustration of a catheter with a hypotube at the proximal side as a reference electrode.

[0035] FIG. 3 A is an illustration of electrodes on a rim of an aspiration catheter or accessory component.

[0036] FIG. 3B is a representation of low frequency impedance measurements in an aspiration catheter.

[0037] FIG. 3C illustrates using high frequency and a pair of RF antenna to monitor impedance of bodily material.

[0038] FIG. 3D illustrates using high frequency and a single RF antenna to monitor impedance of bodily material.

[0039] FIG. 3E illustrates a system for using high frequency to monitor impedance of bodily material.

[0040] FIG. 4 illustrates analyzing clot characteristics for use in determining a clot extraction method.

[0041] FIG. 5A is a diagram of distal embolic protection with sensors and clot.

[0042] FIG. 5B illustrates a system for using impedance to monitor impedance of bodily material.

[0043] FIG. 5C illustrates an embodiment of a distal embolic protection device with a filter.

[0044] FIG. 5D illustrates the distal embolic protection device shown in FIG. 5C filled about 1 / 3 with clot.

[0045] FIG. 5E illustrates the distal embolic protection device shown in FIG. 5C filled about 2 / 3 with clot.

[0046] FIG. 6A illustrates the distal end of a dilator (e.g., obturator) in a deployed state with sensor electrodes.

[0047] FIG. 6B illustrates the proximal end of the catheter illustrated in FIG. 6A, showing the dilator in its collapsed state.

[0048] FIG. 6C illustrates another embodiment with electrodes on a dilator tip.

[0049] FIG. 6D illustrates another embodiment with electrodes on a dilator tip.

[0050] FIG. 7 A illustrates ring electrodes on catheter wall.

[0051] FIG. 7B illustrates ring electrodes on catheter wall.

[0052] FIGS. 7C-7D illustrates a cross-sectional and side view of an inner liner of a multi-layered shaft electrodes and circuitry is affixed.

[0053] FIGS. 7E-7F illustrates a cross-sectional and side view of the second non- conductive layer of a multi-layered shaft having electrodes and circuitry within the wall.

[0054] FIGS. 7G-7H illustrates a cross-sectional and side view of a tie-layer layer of a multi-layered shaft having electrodes and circuitry within the wall.

[0055] FIGS. 71-7 J illustrates a cross-sectional and side view of outer jacket & reinforced braid layers of a multi-layered shaft having electrodes and circuitry within the wall with inwall conductive pads exposed on the distal end and on the exterior wall of the shaft.

[0056] FIGS. 7K-7L illustrates a cross-sectional and side view of multi-layered shafts with conductive rings affixed to exposed conductive pads.

[0057] FIGS. 7M-7N illustrates a cross-sectional and side view of a multi-layered shaft within wall electrode circuitry and exposed distal electrodes built into a catheter having a proximal hub having an aspiration port and a more proximal port attached.

[0058] FIG. 8A illustrates a catheter with an optical emitter and photodetector at its distal tip.

[0059] FIG. 8B illustrates another catheter with an optical emitter and photodetector at its distal tip.

[0060] FIG. 9A illustrates a catheter with a deployed funnel and electrodes on the inside of the funnel.

[0061] FIG. 9B illustrates a catheter with a deployed funnel and electrodes on the inside of the funnel and reference electrode towards the proximal end of the catheter.

[0062] FIG. 9C illustrates another embodiment of a catheter with a funnel and electrodes.

[0063] FIG. 9D illustrates another embodiment of a catheter with a funnel and electrodes.

[0064] FIG. 9E illustrates another embodiment of a catheter with a funnel and electrodes.

[0065] FIG. 10A illustrates a catheter and funnel in a deployed state. The funnel has electrodes on an outside rim.

[0066] FIG. 10B illustrates another view of the catheter and funnel shown in FIG. 10 A.

[0067] FIG. 10C illustrates a system for using impedance for to monitor impedance of bodily material and to control funnel movement.

[0068] FIG. 11 A illustrates a catheter with deployed umbrella spines with electrodes at the end of each of the splines.

[0069] FIG. 1 IB illustrates a catheter with deployed umbrella splines with electrodes at the end of each of the splines showing a spline falling into a tributary or collateral vessel.

[0070] FIG. 11C illustrates a catheter with deployed umbrella splines with electrodes at the end of each of the splines showing a spline falling into a tributary or collateral vessel and encountering a blood clot.

[0071] FIG. 1 ID illustrates another example of reverse umbrella electrodes in a deployed and captured state.

[0072] FIGS. 12A-12C illustrates placement of a distal protection element being placed through a Popliteal access site, an Internal Jugular (IJ) access site, and a Femoral access site.

[0073] FIGS. 13A-13B illustrates the use of an emboli protection device in conjunction with an aspiration catheter where the emboli protection device is placed upstream of the thrombus.

[0074] FIGS. 14A-14B illustrates a catheter having an expandable distal assembly where electrodes expand away from the longitudinal axis of the catheter for sensing vessel or obstruction within a vessel.

[0075] FIGS. 15A-15D illustrates a catheter having an expandable distal sensing assembly where electrodes expand away from the longitudinal axis of the catheter for measuring the diameter of vessel and / or presences of obstruction within a vessel.

[0076] FIGS. 16A-16D illustrates a catheter having a handle with indicator and an expandable distal sensing assembly where electrodes expand away from the longitudinal axis of the catheter for investigating vessel and / or obstructive material on within the vessel

[0077] FIG. 16E illustrates a macerating catheter having a handle with a controllable, expandable distal assembly that is attached to a drive motor that is able to spin the distal assembly.DETAILED DESCRIPTION

[0078] Described herein are apparatuses (e.g., systems, devices, etc.), and methods useful in sizing and treating bodily vessels such as blood vessels. In particular, described are systems, apparatus, and methods that may be especially useful for sizing bodily vessels such as blood vessels, and identifying and removing blood clots or other blockages from a bodily vessel. These methods and apparatuses may be configured to identify a material that is at or near the distal end of a catheter and / or may be configured to identify one or more characteristics of a material at or near the distal end of the catheter. The catheter may be an aspiration catheter. The methods and apparatuses may be configured to monitor one or more electrical property, such as impedance. In some cases one or more additional sensing modalities, in addition to electrical sensing, may be used, such as but not limited to optical information (e.g., reflectance), and / or ultrasound.

[0079] This patent application may be related to, may improve on, and / or incorporate, one or more of features or elements of international application no. PCTUS2022035392, filed June 28, 2022, U.S. patent application no. 17 / 866,462 (filed on July 15, 2022), which issued as U.S. patent no. 11,730,925, and U.S. patent application no. 18 / 329,532, filed on June 5, 2023, each of which is herein incorporated by reference in its entirety.

[0080] In some examples an apparatus may be configured for sensing / detecting and / or identifying clot material (e.g., distinguishing clot material may from other materials, such as vessel wall, blood, etc.) and / or identifying the type of clot material (e.g., soft clot, hard / calcified clot, etc.) and / or extracting clot material. In some cases monopolar sensing may be used. For example, any of these apparatuses may include a catheter (e.g., aspiration catheter) with a monopolar dispersive electrode. FIG. 1 A schematically illustrates an example of a system 100 being used on subject 104. System 100 includes catheter 102, one or more electrode(s) 106 on a distal end region of catheter 102, one or more reference electrode(s) 108, and external apparatus 110. Reference electrode 108 in FIG. 1 A is shown a patch type electrode (a pad) mounted to the skin of subject 104. Electrode 106 is in, on, around, or otherwise connected to catheter 102. Electrode(s) 106 can also be configured as monopolar electrode(s). An external apparatus 110 is shown including aspiration syringe configured for aspirating a blood clot and can also include other components such as a catheter handle, power source, signal generator, microprocessor, memory, etc.

[0081] FIG. 1A also illustrates catheter 102 (with electrode 106 on a distal end region) that has been inserted into a blood vessel in leg of subject 102. In use, system 100 can deliver an electrical current from electrode 106, passing the electrical current through tissues in the patient’s body to a reference electrode 108. The impedance measured at the monopolarelectrode may primarily reflect the region around the monopolar electrode and the resulting signal may be passed to external apparatus 110 for analysis. The impedance value may be referred to as a bioimpedance value.

[0082] System 100 can be used to sense, measure, and / or analyze bioimpedance values across tissues. In particular, system 100 can be used to measure bioimpedance values indicative of blockages in a bodily vessel such as blood clots in a blood vessel. Blood clots or other blockages resist passage of electrical current and this bioimpedance measurement may be useful for detecting or identifying blood clots or other blockages. However, interference from other, unwanted signals (a) from within a subject’s body can overwhelm a bioimpedance system and mask a desired bioimpedance measurement.

[0083] A subject’s body possesses its own forms of energy that may result in artifacts, e.g., due to heartbeat, respiration, body motion, etc., and the signals from such energy (“noise”), including noise from sources outside the body (environmental artifact), can overwhelm a specific or desired bioimpedance signal. A monopolar setup is believed to be more susceptible to these unwanted signals than a local bipolar configuration. The methods and apparatuses described herein may address this susceptibility.

[0084] Any of these apparatuses may include filtering when using monopolar sensing that allows detection of a local monopolar impedance signal out of other signals that will exist simultaneously in the same waveform. These unwanted signals can be filtered out (removed from the signal), typically through digital signal processing (DSP), to better determine the local impedance at the monopolar electrode. Otherwise, these other conditions can have an impact on the measured impedance from a monopolar electrode. When filtered as described herein, the signals can provide an implementation which informs the user of spatially-specific impedance information and can allow for a single-conductor in a catheter shaft, which may simplify the design and manufacturing of the system.

[0085] In general, these methods and apparatuses using a monopolar electrode may apply filtering to the received impedance signal from the monopolar electrode to remove respiration artifact (which may have a characteristic frequency range relative to respiration), hear rate artifact (which may also have a characteristic frequency range relative to respiration), and / or motion artifact. FIG. IB, illustrates the use of filtering to remove these noise components from the signal. Filtering may be based on frequency domain information (e.g., removing or reducing frequency components within the respiration frequency range, e.g., 0.05 and 1.5 Hz, and / or heartbeat frequency range, e.g., between 0.2 Hz and 3 Hz). Very rapid changes in the impedance, e.g., due to motion artifacts, may also be removed.

[0086] Alternatively or additionally, a second monopolar electrode may be used to remove noise, since the second monopolar electrode will be exposed to the same noise background (e.g., heartbeat, respiration, etc.) as the sensing monopolar electrode. The second (or more) electrode may be referred to as a noise-removal electrode and may be the same size as the sensing electrode. In some cases the noise-removal electrode may be adjacent to or nearby the sensing electrode, but may be positioned in a region that is protected from contact, e.g., with a clot material, wall, etc. The signal from the noise-removal electrode may be scaled with the signal from the sensing electrodes. In some cases the noise-removal electrode may be proximal to the sensing electrode and / or may be within a partially enclosed chamber within the catheter (e.g., the distal tip region, etc.).

[0087] For example, a system for detecting a clot in a blood vessel may include one or more of a catheter including a first electrode, the catheter configured for insertion into a blood vessel; a reference electrode for receiving a signal from the first electrode; a non- transitory computer readable storage medium storing a set of instructions capable of being executed by a processor, wherein the set of instructions, when executed by the processor, causes the processor to: obtain a first set of impedance values from a first set of signals from the first electrode, wherein the first electrode is not in contact with a suspected blood clot; obtain a second set of impedance values from second set of signals from the first electrode or a second monopolar electrode in electrical contact with the same or a different reference electrode, wherein the first electrode or the second electrode is in contact with a suspected blood clot; filter the second set of values to remove the first set of values from it to generate filtered values; and determine from the filtered values an impedance value of the suspected blood clot.

[0088] FIG. 1H shows a flowchart 150 illustrating one example of steps that can be taken for detecting an intended target such as a blood clot in a vessel. Flowchart 150 shows the steps of obtaining impedance data 152 from a monopolar electrode (e.g., on a distal end region of a catheter), filter artifact or unwanted signals and / or subtract a signal from the noise-removal electrode (e.g., after registering the signal from the noise-removal electrode with the signal from the sensing signal) 164 to generate filtered impedance values. This filtered signal may then be examined to identify data features to determine if filtered impedance values corresponds to a suspected target 156, such as a blood clot. This method may be particularly useful where there is a size disparity between the sensing and return electrodes (e.g., in a monopolar configuration), typically with a very small sensing electrode and a very large return (e.g., reference) electrode.

[0089] FIG. 1C shows an example of impedance results over time measured using a monopolar electrode before (top panel) and after (bottom panel) filtering to remove unwanted signals. The top panel in FIG. 1C illustrates impedance values over time including respiration artifact 130, heartbeat artifact 132, and body motion or environmental artifact 134, as well as underlying signal 136. After filtering and / or smoothing of the signal, filtered impedance values 140 (e.g., intended monopolar impedance waveform) are shown in the bottom panel. Techniques that may be employed to use in conjunction with filtering include manipulating breath (e.g., including instruction the subject how to breath, the subject holds their breath for a prescribed length of time, the subject breathes with a particular frequency such as IX, 2X, 3X, 4X, 5X, 6X, 7X per minute, the subject breathes with a prescribed depth such as belly breathing). Some embodiments include identifying characteristic waveforms in an individual. Some embodiments include identifying characteristic waveforms in a population or in an environment (such as, in an operating room or due to equipment). For example, a waveform characteristic of a respiration artifact, heartbeat artifact, body motion or environmental artifact, another artifact, or an underlying signal can include one or more of a monophasic spike, a diphasic spike, a triphasic spike, polyspikes, a spike equivalent sharp wave (e.g., an ascending ramp), a sharp wave, etc. A characteristic waveform from an artifact may last from 0.01 seconds to 1 or more seconds and may be isolated or may repeat (e.g., with frequency as long as testing is performed).

[0090] Reference electrode(s) 108 can be a large-area patch electrode such as a conductive, adhesive gel patch with an Ag / AgCl electrode with a conductive hydrogel layer and adhesive or a dry electrode (e.g., conductive textile, gold, stainless steel, carbonized rubber) and can be placed against the skin, such as shown in FIG. 1 A or described elsewhere herein. Such placement provides a low-impedance path from the reference electrode 108 to the subject, so that a bioimpedance measurement made between reference electrode 108 and monopolar electrode 106 on the catheter is nearly completely determined by the local material (e.g., clot vs non-clot) around the monopolar electrode, giving the user local impedance information at the monopolar electrode location. In some variations, a large electrode could also be a conductive structure inside a catheter handle where blood contact is made, a large electrode could be a needle inserted into the leg of the subject, such as at the access site, or the large electrode could be part of another device with consistent low- impedance contact to the body. FIG. 1C graphically illustrates an example of a bar graph 124 showing the relative contributions to impedance measurements of a relatively small monopolar electrode 122 vs a large reference electrode 120. By using a relatively large reference electrode, impedance due to the large electrode is relatively small and reducessignal noise. For example, a large reference electrode may have a surface area of at least 100 mm2, at least 225 mm2, at least 400 mm2, at least 900 mm2, at least 1600 mm2, at least 2500 mm2, at least 3600 mm2or between or less than any of these values (e.g., less than 2500 mm2, less than 1600 mm2, or between 400 mm2and 3600 mm2, etc.).

[0091] FIG. ID schematically illustrates an example of a distal end region 170 of a clot detection system as disclosed herein. FIG. ID illustrates catheter 172 with distal aspiration opening 174, a navigation catheter and / or guidewire lumen 176, and a monopolar proximal edge electrode 178 on the rim at the 12 o’clock position. Catheter 172 is configured to navigate a bodily vessel, such as a blood vessel. Aspiration opening 174 of catheter 172 is configured to accept at least a portion of a clot. When subject to negative pressure / vacuum, opening 174 is also configured to allow the clot to be aspirated through opening, through the catheter and into a collection apparatus (not shown). When catheter 172 is inserted into and along the inside of a blood vessel and encounters a blood clot, part of the clot enters the catheter through opening 174, contacting and even surrounding electrode 178. Electrical signals from electrode 178 (used with a large area return electrode such as shown in FIG. 1 A or described elsewhere herein) may sense impedance due to clot when clot is present. As indicated above, two sets of signals can be obtained using catheter 172. A first set of impedance values from a first set signals can be obtained using electrode 178, wherein electrode 178 is not in contact with a suspected blood clot. A second set of impedance values from a second monopolar electrode can be obtained, wherein electrode 178 is in contact with a suspected blood clot and the second electrode does not contact clot. The second signal from the second electrode can be aligned or synchronized with the first signal using software, and the second signal subtracted form the first signal to remove noise due to heartbeat, respiration, etc. The subtracted signal may be further filtered (smoothed, etc.) and the filtered signal can be used to determine an impedance value that is indicative of suspected blood clot. As indicated above, two sets of signals can be obtained using catheter 172. A first set of impedance values from a first set signals can be obtained using electrode 178, wherein electrode 178 is not in contact with a suspected blood clot. A second set of impedance values from a second set of signals can be obtained, wherein electrode 178 in contact with a suspected blood clot. The filter the second set of values can be filtered to remove the first set of values from it to generate filtered values. The filtered values can be used to determine an impedance value that is indicative of suspected blood clot or indicative that no blood clot is present, clot or indicative that no blood clot is present.

[0092] Unwanted signals may be effectively filtered out using two nearby monopolar electrodes, each using the same (or similar) large-area reference electrode, the waveformsmay be subtracted from each other and the majority of the common-mode noise (in this case, the unwanted signals) can be removed. This is another way of creating a simulated bipolar sensing system. FIG. IE graphically illustrates another embodiment of a distal end region of a detection system. FIG. IE illustrates distal end region 180 of a detection system as disclosed herein. FIG. IE illustrates catheter 182 with a lateral, tapered aspiration opening 174, a navigation catheter and / or guidewire lumen 176 for receiving a navigation catheter and / or guidewire, and monopolar distal ring electrode 188. Catheter 182 is configured to navigate a bodily vessel, such as a blood vessel. When catheter 182 is inserted into and along the inside of a blood vessel and encounters a blood clot, part of the clot may surround distal ring electrode 188. Impedance signal obtained through distal ring electrode 188 (using a large area electrode such as shown in FIG. 1 A or described elsewhere herein) will be impeded by the clot when clot is present. As indicated above, two sets of signals can be obtained using catheter 182. A first set of impedance values from a first set signals can be obtained using distal ring electrode 188, wherein electrode 188 is not in contact with a blood clot. A second set of impedance values from a second set of signals can be obtained, wherein distal ring electrode 188 in contact with a suspected blood clot. The second set of values can be filtered to remove the first set of values from it to generate filtered values. The filtered values can be used to determine an impedance value that is indicative of suspected blood clot or indicative that no blood clot is present.

[0093] FIG. IF graphically illustrates another embodiment of a distal end region of a detection system. FIG. IF illustrates distal end region 190 of a detection system as disclosed herein. FIG. IF illustrates catheter 192 with aspiration opening 174, a guidewire lumen 176, and two monopolar electrodes, proximal edge electrode 178 and distal ring electrode 188. Catheter 192 is configured to navigate a bodily vessel, such as a blood vessel. When catheter 192 is inserted into and along the inside of a blood vessel and encounters a blood clot, part of the clot may surround one or both of proximal edge electrode 178 and distal ring electrode 188. Signal obtained through either or both of proximal edge electrode 178 and / or distal ring electrode 188 may sense clot based on the impedance change when clot is present. Such information may indicate the size of a clot or other characteristics of the clot (e.g., acute or chronic). Furthermore, signals from both (or either) electrodes can be utilized to obtain a first set of impedance values from a first set of signals from the first electrode, wherein the first electrode is not in contact with a suspected blood clot such that a first set of impedance values is obtained from each of proximal edge electrode 178 and distal ring electrode 188. Such values may be combed (e.g., averaged, subtracted, added, etc.) together to generate a new impedance signal and the new impedance signal can be filtered to remove the noise.

[0094] FIG. 1G graphically illustrates another embodiment of a distal end region of a detection system. FIG. 1 G illustrates distal end region 200 of a detection system as disclosed herein. FIG. 1G illustrates catheter 202 with an aspiration opening 174, a guidewire lumen 176, and two monopolar electrodes, first electrode 208a and second electrode 208b. First electrode 208a and second electrode 208b are shown along an outer perimeter of opening 174 at a distal tip of catheter 202. First electrode 208a and second electrode 208b can be on opposite sides of the perimeter (e.g., 180 degrees apart) or can be less than 180 degrees apart. Catheter 202 is configured to navigate a bodily vessel, such as a blood vessel. When catheter 202 is inserted into and along the inside of a blood vessel and encounters a blood clot, part of the clot may surround one or both of first electrode 208a and second electrode 208b. Signal obtained through either or both of first electrode 208a and second electrode 208b (using a large area electrode such as shown in FIG. 1 A or described elsewhere herein) will be impeded by the clot when clot is present, which indicates the presence of clot. Such information may indicate the size of a clot or other characteristics of the clot (e.g., whether the clot is acute or chronic). Furthermore, signals from both (or either) electrodes can be utilized to obtain a first set of impedance values from a first set of signals from each or one or the other electrode, wherein each or one or the other electrode is not in contact with a suspected blood clot such that a first set of impedance values is obtained from each of first electrode 208a and second electrode 208b. Such values may be averaged together to generate a new set of impedance values and the new set of impedance values can be filtered from the second set of values to remove the first set of values (e.g., artifact or background) from it to generate filtered values, which can be used to determine whether or not clot is present.

[0095] In any of these apparatuses a larger return electrode may be used. The return electrode may be greater than 2x, 3x, 4x, 5x, 6x, 7x, 8x, 9x, lOx, 12x, 15x, 20x, 25x or more than the area of the sensing electrode. In some cases a large-area electrode can be as part of the conductive construction of a catheter (such as an aspiration catheter or an accessory catheter). Similarly, other conductive components such as a braid or coil of a catheter shaft, when sufficiently exposed on the interior of the catheter, can be used as a reference electrode for a catheter with monopolar impedance measurement capabilities.

[0096] In some cases the apparatuses for sensing and / or removing clot material described herein may be configured to include a hypotube as art of the assembly, as shown in FIGS. 2A-2C. For example, the hypotube may form all or a portion of a wall of the catheter assembly, including but not limited to an internal channel, e.g., for a navigation catheter and / or guidewire.

[0097] Thus, the large-area electrode of a monopolar pair (as describe above), could be chosen as part of the conductive construction of a catheter (either the aspiration catheter, or an accessory catheter). If a catheter includes a conductive hypotube, that component (as long as it has large areas exposed to the body) could be used as the reference electrode.

[0098] FIGS. 2A-2C schematically illustrate catheters with reference electrodes that can be used with the systems herein. These catheters can be used with one, two, or more monopolar electrodes, including an array of electrodes, for monopolar measurements. FIG. 2A illustrates distal end region 210 of catheter 212. Catheter 212 includes distal opening 214, monopolar electrode 218, and exposed electrode 228. Exposed electrode 228 can be, for example, a braid or coil that is part of the catheter wall and which is exposed on an inside of the catheter. Monopolar electrode 218 and reference electrode 228 are configured to cooperate to provide an impedance value to a microprocessor typically at a proximal end region of catheter 212 in a catheter handle or other apparatus (such as external apparatus 110 shown in FIG. 1A). The impedance value from monopolar electrode 218 is indicative of impedance of its surrounding environment. Catheters, such as catheter 212, can be manufactured with three layers an inner liner layer, a middle layer which may be a braid or other reinforcement layer, and an outer jacket. The middle layer can be made from aluminum, gold, magnesium, molybdenum, nickel, platinum, silver, stainless steel, alloys thereof, such as nitinol, electroactive polymer or another conductive material. The inner liner layer and outer jacket may be manufactured from or coated with a non-conductive material, such as a synthetic resin, such as polyolefin, polyamide, polyetherpolyamide, polyurethane, nylon, or polyether blockamide except that the area of the desired exposed electrode in the inner liner layer will have the conductive layer exposed. The non-conductive material is either not added to or can be removed from this region. In some variations, a conductive material can be overlaid or coated onto an inner layer.

[0099] When a catheter includes a conductive hypotube, that component (as long as it has large areas exposed to the body) can be used as the reference electrode. FIG. 2B illustrates distal end region 230 of catheter 232. Catheter 232 includes distal opening 214, monopolar electrode 218, hypotube 234, and exposed electrode 238 on hypotube 234. Hypotube 234 can be attached to an inner (or outer) wall of a catheter. Monopolar electrode 218 and reference electrode 238 are configured to cooperate to provide an impedance value (such as to a microprocessor typically at a proximal end region of catheter 212 in a catheter handle or other apparatus, such as external apparatus 110 shown in FIG. 1 A) for the local area surrounding monopolar electrode 218. The impedance value from monopolar electrode 218 is indicative of impedance of its surrounding environment. Hypotube 234 can be manufacturedwith an exposed layer of aluminum, gold, magnesium, molybdenum, nickel, platinum, silver, stainless steel, alloys thereof, such as nitinol, electroactive polymer or another conductive material that serve as reference electrode 238. Other parts of hypotube 234 could be manufactured from or coated with a non-conductive material, such as a synthetic resin, such as polyolefin, polyamide, polyetherpolyamide, polyurethane, nylon, or poly ether blockamide except that the area of the desired exposed electrode in the inner liner layer will have the conductive layer exposed. The non-conductive material is either not added to or can be removed from the reference electrode 238 region. In some variations, a conductive material can be overlaid or coated onto an inner layer.

[0100] FIG. 2C illustrates distal end region 250 of aspiration catheter 252. Aspiration catheter 252 has reference electrode 258 towards a proximal end region of aspiration catheter 252. Exposed electrode 258 can be attached to an inner wall of catheter 252. Any one or more than one or array of monopolar electrodes as described elsewhere herein can be present on a distal end region of 218. The one or more or array of monopolar electrodes and reference electrode 258 are configured to cooperate to provide an impedance value (such as to a microprocessor typically at a proximal end region of catheter 252 in a catheter handle or other apparatus, such as external apparatus 110 shown in FIG. 1 A) for the local area surrounding the monopolar electrode(s). The impedance value from the monopolar electrode(s) is indicative of impedance in its surrounding environment, such as a blood clot. Reference electrode 258 can be manufactured as an exposed layer of aluminum, gold, magnesium, molybdenum, nickel, platinum, silver, stainless steel, alloys thereof, such as nitinol, electroactive polymer or another conductive material that serve as reference electrode 258. In some variations, a conductive material can be overlaid or coated onto an inner layer of aspiration catheter 252.

[0101] Thus, in general, the return electrode may be configured as a portion of the elongate catheter (including an outer surface) or an elongate hypotube within the catheter. RF Antenna Sensing

[0102] Another aspect of the disclosure provides a catheter with electrodes (conductors) useful as radiofrequency (RF) antenna.

[0103] As described above, impedance measurements between electrodes on an aspiration catheter may be within a lower frequency range, e.g., less than 10 MHz, such as between about 1kHz to 1MHz. This frequency range may evaluate the impedance of a material in contact with the electrodes themselves as well as the material between them. Alternatively or additionally, one or more electrical conductors in or on a catheter (or an accessory to be used with the catheter) may be configured to use the electrical conductor(s) asan RF antenna. For example, a ground plane for the resulting antenna could be a groundplane of a printed circuitry (e.g., PCBA) in the catheter handle, in another conductor, etc. To treat the conductor(s) as an RF antenna, the frequency of excitation may be much higher than previously described, such as between about 10MHz - 10GHz. If the excitation current is measured, the characteristic impedance of the material in the antenna-profile vicinity of the catheter tip may be determined. The characteristic impedance of clot is typically different from that of blood, so the sensing electrode may sense nearby clot that is not in direct contact with the electrodes themselves. This may allow for visibility beyond direct touch, which may further allow the apparatus to identify when clot is present in the extraction zone of an aspiration catheter.

[0104] For example, the systems, methods and apparatuses described herein may be configured for determining impedance of material in contact with or adjacent to the electrodes themselves, as well as the material between them. As mentioned, in some configurations an RF antenna for transmission / reception can be used to evaluate the characteristic impedance of material in the antenna pattern. For example, described herein is a detecting a blood clot in a vessel, the method including one or more of the steps of inserting, into a first site in a blood vessel suspected of having a blood clot, a catheter including one or more electrodes at a distal end region, wherein each of the one or more electrodes is in electrical communication with a signal generator; transmitting, from the signal generator, a signal between 10MHz - 10GHz; receiving, with each of the one or more electrodes, the transmitted signal from the signal generator, wherein each of the one or more electrodes is not in contact with a blood clot; transmitting, from each of the one or more electrodes, a first transmitted signal to a detector; moving the catheter to a second site in the blood vessel, wherein the second site is suspected of having a blood clot; transmitting, from the signal generator, a signal between 10MHz - 10GHz; receiving, with each of the one or more electrodes, the second transmitted signal from the signal generator; transmitting, from each of the one or more electrodes, the second transmitted signal to a detector; comparing the second transmitted signal with the first transmitted signal and detecting a phase shift between the second and first transmitted signals, wherein the presence of the phase shift is indicative of blood clot at the second site. This is illustrated in FIGS. 3A-3B (showing proximity impedance sensing between a pair of electrodes by low-frequency impedance measurements) and FIGS. 3C and 3D, showing much higher frequency (e.g., RF) antenna sensing.

[0105] As mentioned, the ground plane in such examples can be, for example, a groundplane of a printed circuit board assembly (PCBA) in a handle of a catheter another conductor, etc. To treat the conductor(s) as a radiofrequency (RF) antenna the frequency of excitation ishigh (and typically higher than previously described), such as 10MHz - 10GHz. When the excitation current is measured, the characteristic impedance of the material in the antennaprofile vicinity of the catheter tip can be determined. Since the characteristic impedance of clot differs from blood, so the sensing would be able to sense nearby clot that is not in direct contact with the electrodes themselves. This allows for visibility beyond direct touch (contact), to identify when clot is present in an extraction zone (e.g., a region in a blood vessel that can be extracted) of an aspiration catheter. FIG. 3 A schematically illustrates distal end region 270 of catheter 272 with first electrode 278 attached to sensing wire 282 and second electrode 288 attached to sensing wire 284. First electrode 278 attached to sensing wire 282 and second electrode 288 attached to sensing wire 284 are on a distal rim of an aspiration catheter or another accessory component and the sensing wires run along, on, in, and / or within that catheter body to the proximal end of the elongated catheter. FIG. 3B illustrates how the catheter in FIG. 3 A can measure impedance between electrode 278 and electrode 288. Low frequency impedance measurements (1kHz to 10 MHz for lower frequencies and above this for RF) send small amplitude AC current between electrodes, evaluating the impedance of material at each electrode and the space between. FIG. 3C schematically illustrates how using much higher frequencies (e.g., 10MHz - 10GHz) and treating the conductors / electrodes 278 and 288 as an RF antenna for transmission / reception can evaluate the characteristic impedance of material in the antenna pattern. FIG. 3C shows electric field lines 280 using high frequency of excitation and two spaced apart conductors / electrodes 278 and 288 as shown in FIG. 3B. FIG. 3D shows a single electrode emitting high frequency electrical signals creating Electrical Fields 288 where the single electrode 292 also receives and measures the signal received back for interrogating the fluid and volume within the region around the single electrode 292. FIG. 3E graphically illustrates an example of a system, system 330 for using conductors / electrodes / as RF antenna for transmission / reception can evaluate the characteristic impedance of material in the antenna pattern. FIG. 3E illustrates system 330 can include one or more of electrodes 338 (also referred to herein as conductors), signal generator 342, wireless connector 344, input module 346, processor 332, memory module 334, power module 336, data storage module 340, and output module 348. Although any components illustrated in FIG. 3E may be included in this or other systems herein, a component may also be excluded if not needed in a particular configuration.Lower Frequency (1 kHz-lOMHz)

[0106] As mentioned above, the methods and apparatuses described herein may be used for lower frequency impedance measurements between electrodes on an aspiration catheter. For example, less than 10 MHz, such as between about 1kHz to 10 MHz (e.g., between about 1 kHz to 7.5 MHz, 1 kHz to 5 MHz, 1 kHz to 2.5 MHz, 1 kHz to 1 MHz, etc ). This frequency range may evaluate the impedance of a material in contact with the electrodes themselves as well as the material between them. For example, FIGS. 3A and 3B may be configured for low frequency application of energy.Sensing Acute vs. Chronic Clot

[0107] The methods and apparatuses described herein may also be configured to remove a clot from a blood vessel. In particular, these methods and apparatuses may determine how old and / or how adherent a clot is, e.g., using impedance, in order to help guide or control treatment, and specifically removal, of a clot material. For example, these methods and apparatuses may use the measured impedance values to determine if a clot is an acute clot (which typically has a higher relative impedance change as compared with blood and / or vessel wall) or a chronic clot (which typically has a lower relative impedance change as compared with blood and / or vessel wall).

[0108] For example, a method for extracting a clot from a blood vessel may include one or more of: detecting a blood clot in a blood vessel; determining the blood clot impedance; and removing the blood clot from the blood vessel, wherein, when the blood clot impedance value meets certain data analysis criteria, such as within a magnitude and / or phase range, time-dependent variability features, etc. In some cases, this value may be below a predetermined threshold, removing the clot comprises first aspirating the clot with an aspiration apparatus comprising a catheter with a distal opening and a vacuum source, including positioning the distal opening adjacent the clot and generating, with the vacuum source, a vacuum at the distal opening, wherein, when the blood clot impedance value is at or above a predetermined threshold, removing the clot comprises treating the clot without first aspirating the clot with the aspiration apparatus.

[0109] In some variations, a method for extracting a clot from a blood vessel is provided, that may include, one or more of the steps of detecting a blood clot in a blood vessel; determining the blood clot impedance; and removing the blood clot from the blood vessel, wherein, when the blood clot impedance value is below a first predetermined threshold, removing the clot comprises first aspirating the clot with an aspiration apparatus comprising a catheter with a distal opening and a vacuum source, including positioning the distal opening adjacent the clot and generating, with the vacuum source, a vacuum at the distal opening,,and wherein, when the blood clot impedance value is at or above a second predetermined threshold, removing the clot comprises first treating the clot without aspirating the clot with an aspiration apparatus. Any of these methods may include wherein the clot is a deep vein clot, a deep vein thrombosis (DVT) clot. An aspiration or other catheter may be configured (sized and shaped) to fit in a deep vein. An aspiration or other catheter may have an external diameter of 1 Fr, 2 Fr, 3 Fr, 4 Fr, 5 Fr, 6 Fr, 7 Fr, 8 Fr, 9 Fr, 10 Fr, etc. An aspiration or other catheter may have a maximum external diameter of not more than 1 Fr, 2 Fr, 3 Fr, 4 Fr, 5 Fr, 6 Fr, 7 Fr, 8 Fr, 9 Fr, 10 Fr, etc. An aspiration catheter may have an external diameter of not less than 1 Fr, 2 Fr, 3 Fr, 4 Fr, 5 Fr, 6 Fr, 7 Fr, 8 Fr, 9 Fr, 10 Fr or may have an external diameter between any of these values (e.g., at least 2 Fr and not more than 6 Fr, etc.). An aspiration apparatus can include those described in US Patent Publication No. 2023 / 0405273. Clot impedance value can be determined, for example, using any of the apparatuses and methods herein, such as using sensors (electrodes) either on an aspiration catheter tip or on an accessory extension, to obtain information about the type of clot which is present, particularly in a DVT (deep vein thrombosis) case. A level of chronicity of the clot , such as how old and / or adherent to the wall the clot is, can be used so that the user can choose the appropriate method of clot extraction. Clot which tends to be more acute can be extracted through aspiration, whereas a more fibrous chronic clot may be extracted through non-aspiration, such as using a physical intervention such as a nitinol wire mesh clot retriever device. FIG. 4 schematically illustrates flowchart 280 showing a method for extracting a clot from a blood vessel. FIG. 4 illustrates 293 measuring clot impedance. If impedance is less than a predetermined threshold, the clot is likely acute clot 294 and 295 acute clot (or any clot with an impedance value below a pre-determined threshold) can be treated by 296 aspiration. If impedance is above a pre-determined threshold, the clot is likely a 297 chronic clot and 298 chronic clot (or any clot with an impedance value above the pre-determined threshold) is treated by 299 non-aspiration. In some embodiments, the pre-determined threshold is the same value for determining whether to use aspiration methods or non-aspiration methods. In some embodiments, a pre-determined value is a first value for determining aspiration and a pre-determined value is a second value for determining use of non-aspiration methods. Impedance values falling between the first threshold value and the second threshold may be subject to further analysis.

[0110] In any of these methods and apparatuses the type of clot may be determined based on a relative change in the impedance when detecting clot material as compared with blood. As mentioned, more chronic clot may have a lower change in impedance as compared with more acute clot. Any of these apparatuses or methods may include a second modality (e.g.,optical, pressure, ultrasound, etc.) to confirm that the electrode(s) is / are in contact with clot, or are transitioning between blood and clot, allowing accurate assessment of the change in (delta) impedance. In some cases the apparatus or method may examine the impedance as a ramp or change between blood and clot material. Acute clot may have a change of 3x or greater in the magnitude of the impedance, whereas more chronic clot may change between 1 ,5x and 2x. In some cases, the slope of impedance over time may be used to confirm clot material and may distinguish between acute and chronic clot.Distal Embolic Protection with Sensing[OHl] Also described herein are apparatuses (e.g., systems, devices, etc.), and methods for distal embolic protection with sensing, e.g., impedance sensing. Use filters are one technique for preventing blood clots from migrating to the lungs. One example of a filter is an Inferior Vena Cava (IVC) filter. With this technique, a collapsed filter is typically placed using a catheter, which is advanced to the intended location of the filter. The filter is then pushed out of the catheter, expands, and attaches to the vessel walls, such as to the IVC walls if the filter is an IVC filter. The catheter may be removed, and the filter left in place. Some filters are removed after a period of time and in other cases the filter is left in place long term (permanently).

[0112] If a filter is intended to catch blood clots, such as those migrating towards the lungs, it would be useful to know if such an event has occurred. Described herein are filters including electrodes useful for monitoring for presence or (rough) amounts of blood clots in the filters. Monitoring electrical signals from these electrodes can be used to determine if clots have been “caught” by the filter. In some embodiments, sensing on the filter can also indicate to the user when the filter has adequate contact with the vessel wall during placement. In some embodiments, the sensing can indicate when the filter is occluded and needs attention to reduce the incidence of a total exclusion due to tissue growth or thrombus buildup.

[0113] FIGS. 5A-5B illustrates a system and methods for distal embolic protection with sensing. Blood vessel 300 has wall 302 with lumen 304 and direction of blood flow indicated by arrow 306. (Arrow 306 goes from proximal to distal). FIG. 5A illustrates filter 316 that has been placed in blood vessel 300 in a subject in need of blood clot protection. Filter 316 includes a proximal end region with opening 318, and a distal end region 322. Filter 316 also includes an array 310 of a plurality of electrodes 308 and an electronics module 312. A filter can be made from mesh formed into a basket. Mesh is an interlaced structure with spaces in it configured to allow blood to flow through. It can include strands of metal or non-metal (plastic). A plurality (array) of electrodes can be attached to the basket (to strands in themesh) such that blood in a blood vessel can still flow through the mesh and past the electrodes. Electrodes 308 are arranged as bipole pairs. In some variations, the electrode(s) can be monopoles and the system can further include a reference electrode, as described elsewhere herein. Each bipole pair can assay impedance values independently from the other bipole pairs. FIG. 5A also graphically illustrates clot 314 captured by filter 316. FIG. 5B graphically illustrates electronics module 312 can include one or more of data storage module 1350, Bluetooth transmission module 1352, electrode sensor 1354, and power module 1356. A system 320 for distal embolic protection can include electrodes 1338 (e.g., array 310 of a plurality of electrodes 308; a large reference electrode (patch)). System 320 can also include components configured for use external to the body of the subject, including signal generator 1342, wireless connector 1344, input module 1346, and input module 1348. System 320 can also include components configured for use external to the body of the subject including electronics 1330 including processor 1332, memory module 1334, power module 1336, and data storage module 1340. FIGS. 5C-5E illustrate an embodiment of filter 366 similar as to the filter shown in FIG. 5A. Filter 366 includes an array 370 of a plurality of electrodes 378 distributed on an inside of basket 376. (For clarity, electronics module 312 is omitted from this drawing). Electrodes 378 in filter 316 can be used to detect clot 374 and inform the user of the presence of clot 374 in the filter such as described in US Patent Publication No. 2023 / 0405273. Electrodes 378 may also be used to detect clot 374 and inform the user of the presence of clot 374 in the filter of the capacity (for clot) remaining in filter. When the filter is sufficiently filled (e.g., close to full), a user can aspirate the clot. FIG. 5C illustrates an example of placement of filter 366 in a vein leading to the heart between the renal veins and the heart to prevent blood clots from reaching the heart (RA: right atrium; RV: right ventricle; IVC: inferior vena cava; SVC: superior vena cava). In some variations, filter 366 can be placed in the vein between the iliac veins and the renal veins. FIG. 5C shows a plurality of electrode pairs. Clot has not yet been captured by filter 366. FIG. 5D illustrates filter 366 after time has passed with clot captured in distal end region 362 of filter 366. About 30% of basket 376 of filter 366 is filled with clot. Bipole pairs towards distal end region 362 of filter 366 are in contact with and detect clot 374. Bipole pairs towards proximal end region 364 of filter 366 are not in contact with clot and do not detect clot (e.g., impedance values are lower). In this example, if a 60cc basket is used, then analysis using signals obtained from electrodes 378 in filter 366 indicate that 30% or about 20cc of clot has been captured. Analysis of signals from electrodes 378 can provide a semi -quantitative determination of basket fill (and how much basket capacity is remaining). Such information can be used to fordetermining when filter 366 should be further handled (e.g., subject to aspiration to remove clot; filter removed, etc.)

[0114] FIG. 5E illustrates filter 366 after more time has passed with additional clot (relative to FIG. 5D) captured in distal end region 362 of filter 366. About 60% of basket 376 of filter 366 is filled with clot. Bipole pairs towards distal end region 362 of filter 366 as well as bipole pairs between distal end region 362 and proximal end region 364 are in contact with and detect clot 374. Bipole pairs at the most proximal end region 364 of filter 366 are not in contact with clot and do not detect clot (e.g., impedance values are lower). In this example, if a 60cc basket is used, then analysis using signals obtained from electrodes 378 in filter 366 indicate that 60% or about 40 cc of clot has been captured. Electrodes 378 in filter 366 may be configured and positioned (e.g., placed on an inside of basket 376; placed facing an inside of basket 376) to contact and detect clot when clot is in filter 366. Electrodes 378 can also or instead be utilized to determine if filter 366 is appropriately seated against a vessel wall. In this example, when filter 366 is placed appropriately in a vessel, analysis of signals from electrodes at distal end region 362 showing greater impedance values could indicate that they are in contact with vessel wall. Analysis of signals from electrodes at proximal end region 364 and / or electrodes between distal end region 362 and proximal end region 364 showing lower impedance values could indicate that these electrodes are not in contact with vessel wall. Alternatively, when filter 366 is located inappropriately in a vessel, analysis of signals from electrodes at distal end region 362 showing relatively lower impedance values could indicate that they are not in contact with vessel wall. Analysis of signals from electrodes at proximal end region 364 and / or electrodes between distal end region 362 and proximal end region 364 showing relatively higher impedance values (than electrodes at distal end region 362) could indicate that these electrodes are not in contact with vessel wall. Electrodes useful for determining the position of filter 366 may be positioned the same (first configuration) as described above or may be configured and positioned in a second configuration (e.g., placed on an outside of basket 376; placed facing an outside of basket 376; placed on a periphery of opening 318). Pairs of electrodes can be positioned at different heights (h) (separated) along a proximal -distal axis (e.g., along an X-axis direction; see FIG. 5C inset), such as two pairs, three pairs, four pairs, five pairs, six pairs, seven pairs, eight pairs, or more than eight pairs. In some embodiments, multiple pairs can be placed as shown. A filter can have a plurality of electrodes in a first configuration, a second configuration, or in both first and second configurations. In some embodiments, a small integrated circuit can be attached to the filter and a state of the filter can be transmitted out to a nearby receiver, such as by using Bluetooth low energy (BTLE), WiFi direct, Z-wave, Zigbee, etc. This same embodiment could be usedas a 30-90 day implantable IVC filter. The electronics package shown in FIG. 5A, could store the status of the filter with any of several forms of data storage and could be read back upon removal of the filter. In some variations, a filter herein such as filter 316 includes an antenna that can be integrated therein to broadcast a signal that can be picked up by a receiver. Data obtained from electrodes could be broadcasted out of the blood vessel / subject’s body to a receiver that is placed over IVC. Advantages of the filter disclosed herein can include one or more of using smaller distal basket options (length) which can be more easily sheathed and deployed; providing information to a user about what is happening in the distal embolic protection; providing a quantification or semi -quantification of the amount of clot caught in the filter; informing the user that the filter is seated appropriately (or inappropriately) against the vessel wall, etc. Described herein are embolic filters for removing clots from a blood vessel in a subject, including an embolic filter basket with a proximal end region and a distal end region, the filter basket comprising a mesh configured to catch clots and allow blood to pass through; a plurality of bipolar electrode pairs configured to sense impedance adjacent the filter basket; and an electronics module on the filter basket, wherein the electronics module in electronic communication with the bipolar electrode pairs, the electronics module including one or more of an electrode sensor module, a power module, a data storage module, and a short-range wireless module.Dilator with Sensing

[0115] Also described herein are dilators configured to include sensing, e.g., impedance sensing on the tapered end of the dilator. Thus, any of the apparatuses (e.g., systems, devices, etc.) and methods for removing a clot from a blood vessel may use one or more accessory apparatuses or extensions, such as a dilator, that may also or alternatively include sensing. For example, described herein are method of removing a clot from a blood vessel in a subject, including the steps of advancing, in a blood vessel of a subject, a distal end region of an accessory extension, wherein the accessory extension includes a distally flattened cone shape and wherein the accessory extension protrudes from a distal end region of a catheter; sensing a plurality of levels of impedance from a plurality of electrodes on the protruding distal end region of the accessory extension, wherein the electrodes are positioned along a slant height of the cone-shaped accessory extension, and wherein the sensing of the plurality of impedance levels takes place continuously or step-wise; determining, with a processor, that an impedance magnitude is indicative of a clot and is not indicative of blood or of a blood vessel wall; removing the accessory extension from the blood vessel and catheter while leaving the catheter in place in the blood vessel; advancing a clot remover to or beyond the distal end region of the catheter, wherein the clot remover comprises a vacuum aspirator ornon-aspiration grabbing tool; and removing, with the clot remover, the clot from the blood vessel.

[0116] FIG. 6A illustrates a distal end region 404 of a detection system including catheter 402 having diameter 432 and dilator 406 (e.g., obturator) protruding from distal end region 416 of catheter 402 in a deployed state. FIG. 6A also illustrates dilator 406 including first electrode 408 (a ring electrode) with first lead 412 electrically connecting first electrode 408 to external electronics, second electrode 410 (a ring electrode) with second lead 414 electrically connecting second electrode 410 to external electronics, third electrode 418 (a stud electrode) with third lead 422 electrically connecting third electrode 418 to external electronics, and fourth electrode 420 (a stud electrode) with fourth lead 424 electrically connecting fourth electrode 420 to external electronics. FIG. 6A also illustrates dilator 406 with guidewire port 426 and guidewire 428 extending distally through guidewire port 426. FIG. 6A also illustrates that the dilator includes cone-shape with the third and fourth electrodes along a slant height of the cone-shaped portion of the dilator. A distance between an opening of catheter 402 and 420 is represented by dl. In use, dl represents the distance between an electrode that has detected a clot and an end of the catheter for aspirating the clot. In some methods, the distance dl is reduced during clot removal,

[0117] FIG. 6B shows an example of a proximal end of the catheter and dilator shown in FIG. 8, showing the catheter 402 having an aspiration port e448 and coupled to a hemostasis valve 450; a dilator 406 is shown inserted through the catheter, and the proximal end of the dilator may include an indicator (e.g., light or other output) 460 and a controller 458, power source 456, etc. to control operation of the electrodes on the dilator. The dilator may also include a proximal access port 452 for the guidewire lumen 454 (a guidewire is not shown inserted into this lumen in FIG. 6B).

[0118] Large bore catheter systems with an eri face opening at the distal end region may make use of a dilator when advancing the catheter through the vasculature. Electrodes placed in various locations on the dilator inform the user of the condition (of the blood vessel) at the tip. Monitoring the electrical signals from electrodes at the tip of an accessory extension, such as a dilator, is used to determine when tip is in contact with blood, vessel wall, clot, etc. using methods such as those described in US Patent Publication No. 2023 / 0405273. The location of the sensors on the dilator can be positioned such that when the electrodes detect that the aspiration orifice of the aspiration catheter is already positioned proximate to the clot within a desired clot extraction zone. In addition, electrodes on sides of the dilator could be used to determine if the dilator is in full contact with the vessel wall, indicating that the current vessel size is equal to or less than the diameter of the dilator.

[0119] FIG. 6C illustrates distal end region 474 of another detection system. Distal end region 474 is similar as to distal end region 404 described above except that dilator 476 at distal end region 474 includes 2 ring electrodes, first ring electrode 478 and second ring electrode 480, on slant height at a distal end region 472 of dilator 476.

[0120] FIG. 6D illustrates distal end region 484 of another detection system. Distal end region 484 is similar as to distal end region 404 described above except that dilator 486 at distal end region 484 includes a pair 488 of stud electrodes, on slant height at a distal end region 482 of dilator 486.Electrodes within the catheter wall

[0121] Also described herein are apparatuses (e.g., catheters) that may include one or more sensing electrodes within the catheter wall. For example, apparatuses (e.g., systems, devices, etc.) and methods for identifying and distinguishing different types of material (blood, clot, vessel wall, etc.) at a distal tip of a catheter in a blood vessel may include one or more electrodes formed within the wall of the apparatus. FIGS. 7A and 7B illustrate different arrangements for electrodes on an eri face aspiration catheter. FIG. 7A illustrates distal end region 490 of catheter 492. Catheter 492 includes an outer surface 494 and an inner surface 496. FIG. 7A also illustrates first ring electrode 506 and second ring electrode 508 on the distal end region of catheter 492. Second ring electrode is a distance d2 from a distal most end of catheter 492. First ring electrode 506 and second ring electrode 508 are separated by a distance d3. Monitoring the electrical signals from electrodes at the tip of the catheter can be used to determine when tip is in contact with blood, vessel wall, clot, etc. using apparatuses and methods such as those described in US Patent Publication No. 2023 / 0405273 and elsewhere herein, including external electronics, electronics in or on a catheter handle, etc.

[0122] FIG. 7B illustrates distal end region 520 of catheter 522 in a cut-away view. Catheter 522 includes an outer surface 524 and an inner surface 532. FIG. 7B also illustrates two bipolar electrodes outer or first ring electrode 536 (in cross section) on the outer surface 524 of catheter 522 and inner or second ring electrode 538 (in cross section) and on inner surface 532 of catheter 522. Electrical lines 528 and 530 (e.g., wires) may connect the electrodes at the distal end to a proximal connector (not shown). An outermost part of second ring electrode 538 is separated by a distance d4 from an innermost part of first ring electrode 536 in the wall of catheter 492. In some variations, first and second ring electrodes are monopolar electrodes and a reference electrode (e.g., patch electrode, hypotube electrode, etc.) such as described elsewhere herein is utilized. Monitoring the electrical signals from electrodes at the tip of the catheter can be used to determine when tip is in contact with blood, vessel wall, clot, etc. using apparatuses (e.g., systems, devices, etc.) and methods such asthose described in US Patent Publication No. 2023 / 0405273 and elsewhere herein, including external electronics, electronics in or on a catheter handle, etc. A catheter can have a pair of ring electrodes or a plurality of / multiple pairs of rings on the inside or the outside of the distal end region of a catheter. The material at distal end region of the tip (blood, clot, vessel wall, etc.), can be determined by monitoring electrical signals from the electrodes. Provided herein is a clot aspiration catheter, including a proximal end region and a distal end region; and one or more pairs of ring electrodes at a distal end region of the clot aspiration catheter, wherein one or more pairs of ring electrodes are configured to cooperate to provide an impedance value to a microprocessor.

[0123] Thus, a catheter may include one or more electrodes (for sensing impedance) formed within the wall of the catheter by forming different layers of the catheter, as illustrated in FIGS. 7C-7J. FIGS. 7C-7K illustrated sensing electrodes manufactured by exposing an area of conductive material from electrodes that are embedded within the wall of the elongated aspiration. The electrodes in this embodiment are at the distal end region (aspiration orifice) of the aspiration catheter and configured as two electrodes spaced apart to allow them to measure the electrical signal between them. It should be understood that this is only an example, and the conductive exposed area could be larger, the number of discreet electrodes could be increased or decreased, and the exposed area could be exterior facing, internal facing, and / or exposed in all three directions. In this current embodiment, the electrodes are exposed on the distal end region to monitor what the aspiration orifice comes in contact with. Figures below show an example of how this embodiment can be constructed.

[0124] For example, FIG. 7C and 7D show an example of an inner liner of a multilayered shaft electrodes to which circuitry is affixed to the catheter body 540. The inner layer 542 is shown in this example, the electrodes 576, 578 at the distal end (in an eri face configuration in this example, though other placements may be used) are formed on the inner layer and electrical traces (e.g., connecting wires) 552, 554 are shown on the tubular surface. Proximal contacts 548, 550 are formed at the proximal end. FIGS. 7E and 7F so a cross- sectional and side view of the second non-conductive layer of a multi-layered shaft having electrodes and circuitry within the wall. In this example the insulative (e.g., non-conductive) layer 560 has been added to the outside of the catheter from FIGS. 7C-7D; openings may be left or formed over the electrodes and electrode proximal contacts 568, 570. In FIGS. 7G-7H a tie-layer layer 580 of a multi-layered shaft having electrodes and circuitry within the wall has been added, again forming or leaving openings over the electrodes and electrode proximal contacts 568, 570. An outer jacket 600 may then be added over this, as shown in FIGS. 71 and 7 J, which may include reinforced braid layers 602 of a multi-layered shafthaving electrodes and circuitry within the wall with in-wall conductive pads exposed on the distal end and on the exterior wall of the shaft. FIGS. 7K and 7L illustrate the addition of proximal conductive rings 628, 630 affixed to the exposed conductive pads 568, 570 at the proximal end. Finally, FIGS. 7M-7N show an example of the resulting in-wall electrode circuitry and exposed distal electrodes 576, 578 built into a catheter 640 having a proximal hub 660 having an aspiration port 664 and a more proximal port 666 attached.Optical Sensors on the Distal end of Catheter

[0125] Another aspect of the disclosure provides apparatuses and methods utilizing clotdetecting optical sensors. An optical emitter and a detector can be placed at the tip of a catheter, such as aspiration catheter. The frequency of the emitter and detector can be chosen such that the material at the tip can be ascertained.

[0126] FIG. 8A illustrates catheter 722 at a distal end region of a detection system with an optical system. Catheter 722 includes an optical emitter 724 and an optical detector 726 at a distalmost end of catheter. The optical system is useful for identifying characteristics of material, including type and / or amount, that is adjacent to or within a catheter using one or more optical sensors. In use in a blood vessel, optical signal generated from optical emitter 724 can be detected by optical detector 726. In the presence of clot, the signal from the emitter 724 is blocked by the clot. This setup can detect clot in the orifice as clot will block the transmission of light from the emitter to the detector. FIG. 8B illustrates another catheter with an optical system. FIG. 8B illustrates distal end 740 of catheter 742 includes an optical emitter 724 and an optical detector 746 at a distalmost end of catheter. The optical system is useful for identifying characteristics of material, including type and / or amount, that is adjacent to or within a catheter using one or more optical sensors. In use in a blood vessel, optical signal generated from optical emitter 724 is reflected by material in a blood vessel and the reflected light can be detected by optical detector 746.

[0127] Any of the methods and / or apparatus for optical sensing described herein may be used with an electrical (e.g., impedance) monitoring / sensing. Alternatively, a method or apparatus may just use optical sensing. Described herein are methods and apparatuses (e.g., devices, systems, etc., including software, hardware and / or firmware) for interpreting and analyzing sensed data, including sensed optical and / or electrical (e.g., impedance) data, and in particular optical data collected by one or more optical sensors (emitters and / or receivers) placed on or near the aspiration orifice, within the lumen of the catheter, etc. In some cases the data may be collected from optical sensors placed on or near the rim of an aspiration orifice of a thrombectomy catheter. In some cases the data may be collected from optical sensors placed on or within the aspiration lumen of a thrombectomy catheter. These methodsand apparatuses may process sensed optical data to characterize (e.g., classify and / or quantify the sensed material) external to and / or internal to the catheter during a thrombectomy procedure. The sensed optical data may be collected periodically or continuously or some combination of the two. For example, the sensed data may be collected with frequency of between about 0.2 Hz to 1 MHz). In some cases the sensed data may be collected continuously. In some cases the sensor(s) may be turned on for one or more durations that may be periodic or on-demand. The sensed data may be examined over a window of time (e.g., to determine changes within the window of time corresponding to one or more conditions and / or materials. In some cases the sensed optical data (and / or additional sensing modality data) may be analyzed as a stream of data (e.g., data stream). The methods and apparatuses for analyzing the data streams described herein may identify / classify material within the catheter and / or at or near a distal end region (tip) of the catheter, including characterizing the material within a classifications / identification state, such as: air, saline, blood, non-blood tissue (e.g., tumor, vessel wall, etc.), clot (and in particular type of blood clot such as acute or chronic). The non-blood tissue, referred to herein as simply “tissue” may be characterized as vessel wall and / or type of tissue (e.g., common tissues including inferior vena cava (IVC), main pulmonary artery (MPA), right pulmonary artery (RPA), and left pulmonary artery (LPA), etc.).Sensing Electrodes on Aspiration Funnel

[0128] In general, sensing electrodes (e.g., impedance sensing electrodes) may be included on a funnel (including collapsable / expandable funnels) for aspiration. For example, an apparatus (e.g., a system, device, etc.) and / or a methods for detecting (and removing) a clot from a blood vessel using a catheter with an expanded distal end, e.g., a funnel. A funnel at a distal end can aid in directing thrombus into an aspiration or other catheter and to restrict the blood flow over the catheter. FIG. 9A illustrates catheter 762 at a distal end region 760 of a system. Catheter 762 includes funnel 764, the funnel has inner surface 766 and outer surface 768. FIG. 9A illustrates inner surface 766 with an array 770 of first electrodes 772 thereon and outer surface 768 of funnel 764 with an array 774 of second electrodes 776. Monitoring the electrodes for electrical signals can inform the user if they are in contact with thrombus. The electrical monitoring can be impedance or any other technique.

[0129] FIG. 9B illustrates distal portion of catheter 782 at a distal end region 780 of a detection system and more proximal portion 796 of catheter 792. Catheter 782 includes funnel 784, the funnel has inner surface 766 and outer surface 768. FIG. 9B illustrates inner surface 766 with array 790 of electrodes 792 thereon. Counter electrode 794 is on proximal portion 796 of catheter 792. Described herein is a clot aspiration catheter, including aproximal end and a distal end; a funnel at the distal end, the funnel having an inner surface and an outer surface; and an array comprising a plurality of electrodes, wherein the array is on either the funnel inner surface or the funnel outer surface, wherein the electrodes in are configured to cooperate to provide an impedance value to a microprocessor. Monitoring the electrodes for electrical signals can inform the user if they are in contact with thrombus. The electrical monitoring can be impedance or any other technique.

[0130] FIG. 9C illustrates another catheter with an electrical (impedance) detection of blood vessels, clots, and other materials. FIG. 9C illustrates distal end 800 of a catheter 802 with a distal funnel 804, a plurality 810 of electrodes 806 and electrodes 808. Electrodes 806 and electrodes 808 are at different relative distances from the distalmost end of funnel 804. Electrodes are electrically connected to the proximal end of the system and external electronics as described elsewhere herein via leads, such as first lead 812 and second lead 814.

[0131] FIG. 9D illustrates another catheter with an electrical (impedance) detection of blood vessels, clots, and other materials. FIG. 9D illustrates distal end 820 of a catheter 822 with a distal funnel 824, a plurality 830 of electrodes 826, 825, 827. The electrodes are at arranged as lines of electrodes at different relative distances from the distalmost end of funnel 804. Electrodes are electrically connected to the proximal end of the system and external electronics as described elsewhere herein via leads, such as first lead 832 and second lead 834.

[0132] FIG. 9E shows another example of a catheter 840 including a distal funnel 844 (e.g., aspiration funnel) at the end of an elongate catheter body 842. The funnel is shown in a deployed state similar to that shown in FIGS. 9A-9D, in which a mesh 846 of an electrically conductive material (e.g., Nitinol), forms a single electrode on the funnel, and a second electrode (band electrode 848) is located proximally.

[0133] Alternative examples of funnel electrodes are shown in FIGS. 10A-10B. For example, described herein are apparatuses (e.g., systems, devices, etc.) and methods for detecting (and removing) a clot from a blood vessel using a catheter with a deployable expandable distal end chamber. The expandable chamber when deployed can be used for capturing and macerating thrombus. The shape of the deployed chamber can take on various configurations such as circular, elliptical, square, rectangular, polygonal, curvilinear, star or other cross-section shape. In general, when deployed, the chamber maximum diameter should not exceed the diameter of the vessel in which it is deployed. Described herein is a set (one or more) of electrodes on the largest part of the expandable chamber. Electrical signals (e.g., impedance) between these electrodes can be monitored to determine when the chamber hasbeen expanded sufficiently such that it is in contact with the vessel wall. These signals can be continuously monitored and analyzed with a processor. A processor can be attached to a controller which can be used to adjust the diameter of the chamber such that it is not larger than the vessel diameter. In some embodiments, the diameter of the chamber can be continuously adjusted as the catheter and expandable chamber are advanced through a blood vessel. FIG. 10A illustrates a catheter and funnel a deployed state with a plurality of electrodes 868 on the outermost portion of the chamber. FIG. 10A illustrates distal end region of a detection system with catheter 862 and expandable chamber 864 connected thereto in blood vessel 872. FIG. 10A also shows blood vessel 872 has a wall 866 and a lumen 870. FIG. 10C illustrates a system useful with the catheter 862, expandable chamber 864, and electrodes 868 illustrated in FIG. 10A for detecting and / or removing a clot from a blood vessel. Described herein is a system for capturing clot from a blood vessel in a subject, including a catheter having a proximal end and distal end, wherein the catheter is configured for insertion into a blood vessel; an expandable deployable chamber at the distal end of the catheter, the expandable deployable chamber having a proximal end and a distal end and a distal rim surrounding a distal opening, wherein the expandable deployable chamber is in either (i) a first radially expanded configuration or (ii) a second radially compact configuration, wherein the expandable deployable chamber comprises a material configured to repeatedly transform between the first expanded configuration and the second compact configuration; and a plurality of electrodes at the distal rim of the expandable deployable chamber.

[0134] FIG. 10B illustrates another view of the detection system illustrated in FIG. 10A with catheter 862 and expandable chamber 864. Expandable chamber 864 extends from narrow neck region 874.Reverse Umbrella Configuration

[0135] In some cases, the apparatus or method may use one or more spines with sensing electrodes. In some cases, these spines may project proximally. For example, FIG. 11 A illustrates a reverse umbrella with splines. FIG. 11 A illustrates distal end 880 of another detection system with catheter 882, distal shaft 894, and a plurality of movable splines 884 attached at a distal tip 892 of shaft 894. The reverse umbrella apparatus can be used for vessel sizing. The apparatus can have two states, captured and deployed, and may be able to take any configuration between the two states as it moves between the captured and deployed states. When deployed, spines (typically unable to damage the vessel wall) on springs are allowed to extend out from a central point, similar to a reverse umbrella shape. The spines can be of the same length or varying length. Some of the spines can extend to the vessel walland others will remain inside the vessel lumen (e.g., without contacting the vessel wall). Electrical signals from each of the spines can be monitored to determine which of the spines are in contact with the vessel wall. Using knowledge of the length and angle of each of the spines, the vessel diameter can be gleaned.

[0136] The “reverse umbrella” can alternatively be utilized to detect the presence of side branches from a main vessel or the presence of clot in these side branches. As the reverse umbrella is moving through a vessel, some of these splines may enter side branches. Doing so causes the spine to lose contact with the vessel wall, indicating that a side branch has been located. A catheter with deployed umbrella spines with electrodes at the end of each of the spines can result in a spline falling into a tributary or collateral vessel. This can provide information to the user that a collateral vessel is in proximity of the catheter tip. FIG. 1 IB illustrates blood vessel 872 with side branch 888. Spline with electrode 886b contacts vessel wall 866 and will sense increased impedance. Spline with electrode 886a extends into side branch 888 and will sense lower impedance (e.g., due to contacting blood). A reverse umbrella can also be used to locate or detect clot in a side branch of a vessel. A catheter with deployed umbrella splines with electrodes at the end of each of the splines showing a spline falling into a tributary or collateral vessel containing clot. This can provide information to the user that there is clot in a tributary or collateral vessel. FIG. 11C illustrates blood vessel 872 with side branch 888 with clot 896. Spline with electrode 886c extends into side branch 888, but now contacts a clot and will sense intermediate impedance values, indicative of clot.

[0137] FIG. 1 ID illustrates another embodiment of a reverse umbrella configuration. In FIG. 1 ID, the apparatus include a distal sheath 1105 that may be used to close the selfexpanding umbrella-like structure 1115 by advancing this umbrella-like structure distally over an inner member 1125. The umbrella 1115 may be coupled to an outer member 1135 that may slide axially distally and proximally relative to the inner member 1125. In this example, the proximal umbrella may self-deploy when withdrawn proximally out of the distal sheath, that may hold it in a collapsed configuration, e.g., for deployment. Both the sheath and the umbrella may include electrodes. For example, an electrode pair 1107, 1108 on the sheath may sense clot when the distal end is positioned through the clot material. An electrode pair 1117, 1118 on the umbrella structure 1115 may detect when clot is within the umbrella’s proximally facing opening. In operation, the device may be advanced with the umbrella in the collapsed configuration within the distal sheath, until it reaches and extends past the clot material, which may be detected by impedance sensing from the sheath electrodes. Once it is past the clot, the outer member 1135 may be held in position while advancing the sheath, on the inner member 1125 further distally. The umbrella may self-expand and may be withdrawn proximally by pulling on the outer member or both the outer and inner members, to capture clot within the umbrella, which may be sensed by the electrodes 1117, 1118. Thereafter, the distal sheath may be pulled proximally over the umbrella, collapsing it down over the clot material and capturing clot material within the umbrella, while allowing it to be withdrawn proximally to remove clot. In some cases this system may be used with aspiration, e.g., within or proximal to the basket, e.g., through the outer member 1135.Sensing on Distal Protection Elements

[0138] Also described herein are methods and apparatuses that may include a distal protection device (e.g., filter, funnel, cage, etc.) that may include one or more electrodes (or bipolar pairs of electrodes) configured as described herein and incorporated by reference to detect clot material in contact with the distal protection device by impedance sensing. For example, FIGS. 12A-12C illustrate a distal protection device 1205 that may include one or more (e.g., a pair of bipolar) sensing electrodes. The distal protection device includes a tether 1208 that may leave the body and may include the electrical connection to the one or more sensing electrodes. Thus, a sensing system may be included, connected to the distal protection to detect when clot material is in contact with the distal protection device, which may indicate, for example, that is safe to remove, or if further treatment / process should be performed. In FIG. 12A the access is through a lower body region (e.g., femoral or popliteal). In FIG. 12B access may be through the Internal jugular vein (IJV). In FIG. 12C contralateral accesses (e.g., femoral or popliteal) may be used.

[0139] Any appropriate distal protection device may be used, including a laser cut tube, a braided wire, etc. The distal protection device may be expanded, tethered or otherwise anchored into place.

[0140] FIGS. 13A-13B illustrate another example, of clot capture using aspiration with a distal member, e.g., basket, balloon, umbrella, etc. (similar to FIG. 1 ID). In this example, a distal member (e.g., basket, balloon, umbrella etc. ) may be positioned distally, including anchoring distally, as shown in FIG. 13 A, and the aspiration catheter may be advanced distally towards the distal member, as shown in FIG. 13B, while aspirating. For example, in some cases a mechanism may be employed while applying suction (e.g., through a syringe or other source of suction). Either or both the distal member and the catheter may include one or more (e.g., a pair of) sensing electrodes for sensing impedance and therefore clot.

[0141] For example, FIGS. 14A-14B illustrate another example of an apparatus in which a distal element includes an expandable member (e.g., basket, balloon, splines, etc.) that include sensing electrodes. As shown in FIG. 14A, the catheter may include a navigation portthrough which the expandable distal member may advance in a compact configuration. The electrodes may be extended / expanded, as shown in FIG. 14B, showing the deployed state. This may be used instead of or in addition to contrast angioradiography to sense clot.

[0142] FIGS. 15A-15D illustrate one example of a system and method for operating a similar to that shown in FIGS. 14A-14B. In this example the proximal end (shown in the left side) may include a handle with an output 1525 (e.g., LED) and a deployment control (e.g. lever) 1518 that may be used to convert the distal element from the delivery / compact configuration into the expanded deployed configuration. FIG. 15A shows the device in an undeployed configuration, inserted through the aspiration catheter (e.g., through a navigation channel of the aspiration catheter). FIG. 15B shows the device in a deployed state, with the control (lever 1518) actuated to deploy the expandable distal end region; sensing may be used to determine if clot is present. In the example shown in FIG. 15B clot is present and sensed, while in the example of FIG. 15C, no clot is present or detected (as only wall is contacted). FIG. 15D shows the apparatus being inserted through clot material, which may also (even with the expandable distal end undeployed) detect clot.

[0143] In some examples the expandable distal member may be configured to assist in removing clot material in addition to sensing it. In any of these apparatuses a macerator or clot cutting element may be included and may include sensing (e.g., by including impedance sensing electrodes). For example, FIGS. 16A-16E illustrate another example of an apparatus having an expandable distal end member that includes one or more sensing electrodes or electrode pairs. In FIG. 16A the device, which may be similar to that shown in FIGS. 14A- 14B and 15A-15D, includes a handle with a control 1618 for actuating the expandable distal end 1625 to expand from a compact configuration to a deployed configuration, and an output (e.g., indicator, such as an LED in this example) for indicating when clot material is contacting the expandable distal end region. In This example, the expandable distal end region is configured as a set of expandable splines including sensing electrodes 1608, 1608’. In FIG. 16A the device has been deployed so that the electrodes contact the wall of the vessel lumen, but do not indicate clot material. In FIG. 16B the device has been deployed within clot material (e.g., acute clot) as shown. The indicator is shown (e.g., to illuminated as “green”) indicating acute clot based on the impedance sensed (e.g., or he change in impedance as compared with blood. In FIG. 16C the indicator shows that he expandable member and sensing electrodes detect an impedance consistent with subcutaneous clot. FIG. 16D illustrates an example in which the deployed member and sensing electrodes are in contact with acute clot, which may be distinguished based on the impedance, or the change in impedance as compared with blood.

[0144] In any of these examples the distal end region (deployable member) 1625 may be configured to rotate or otherwise move to remove, e.g., scape, clot material once sensed. For example, in FIG. 16E the distal end region may rotate to apply a radial shear force against the clot to remove it; this apparatus may be used in combination with an aspiration catheter to remove clot material. In some examples the sensing may provide feedback to help control the removal of clot material. For example the apparatus may include a user interface, e.g., in the handle, to set the radial force of the distal rotating element, which may be an expandable cage or set of splines that may be rotated manually and / or by a rotating motor driver. The rate of rotation may be adjusted based on the sensed impedance. In addition, the aspiration may be turned on / off in combination with the sensed impedance and / or the activation of the motor. Thus, any of these apparatuses may be configured as a variable-speed maceration device with sensing electrodes to sense the clot type and / or provide feedback to the user on how much force to deploy / expand. In some cases the apparatus may introduce a new (non-sensing) catheter device in place of the sensing, expandable catheter to macerator or the same catheter device may both expand, sense and macerate (e.g., cut clot). The rotation of the distal element may scape and / or macerator and / or dislodge clot either without or (preferably) with aspiration active. The rotational member may be set to a particular deployed diameter and / or rotational speed based on the sensed impedance.

[0145] The terms “individual”, “subject”, and “patient” refer to any subject for whom diagnosis, treatment, or therapy is desired. In some aspects, the subject is a mammal. In some aspects, the subject is a human being.

[0146] Any of the methods (including user interfaces) described herein may be implemented as software, hardware or firmware, and may be described as a non-transitory computer-readable storage medium storing a set of instructions capable of being executed by a processor (e.g., computer, tablet, smartphone, etc.), that when executed by the processor causes the processor to control perform any of the steps, including but not limited to: displaying, communicating with the user, analyzing, modifying parameters (including timing, frequency, intensity, etc.), determining, alerting, or the like. For example, any of the methods described herein may be performed, at least in part, by an apparatus including one or more processors having a memory storing a non-transitory computer-readable storage medium storing a set of instructions for the processes(s) of the method.

[0147] While various embodiments have been described and / or illustrated herein in the context of fully functional computing systems, one or more of these example embodiments may be distributed as a program product in a variety of forms, regardless of the particular type of computer-readable media used to actually carry out the distribution. Theembodiments disclosed herein may also be implemented using software modules that perform certain tasks. These software modules may include script, batch, or other executable files that may be stored on a computer-readable storage medium or in a computing system. In some embodiments, these software modules may configure a computing system to perform one or more of the example embodiments disclosed herein.

[0148] As described herein, the computing devices and systems described and / or illustrated herein broadly represent any type or form of computing device or system capable of executing computer-readable instructions, such as those contained within the modules described herein. In their most basic configuration, these computing device(s) may each comprise at least one memory device and at least one physical processor.

[0149] The term “memory” or “memory device,” as used herein, generally represents any type or form of volatile or non-volatile storage device or medium capable of storing data and / or computer-readable instructions. In one example, a memory device may store, load, and / or maintain one or more of the modules described herein. Examples of memory devices comprise, without limitation, Random Access Memory (RAM), Read Only Memory (ROM), flash memory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical disk drives, caches, variations or combinations of one or more of the same, or any other suitable storage memory.

[0150] In addition, the term “processor” or “physical processor,” as used herein, generally refers to any type or form of hardware-implemented processing unit capable of interpreting and / or executing computer-readable instructions. In one example, a physical processor may access and / or modify one or more modules stored in the above-described memory device. Examples of physical processors comprise, without limitation, microprocessors, microcontrollers, Central Processing Units (CPUs), Field-Programmable Gate Arrays (FPGAs) that implement softcore processors, Application-Specific Integrated Circuits (ASICs), portions of one or more of the same, variations or combinations of one or more of the same, or any other suitable physical processor.

[0151] Although illustrated as separate elements, the method steps described and / or illustrated herein may represent portions of a single application. In addition, in some embodiments one or more of these steps may represent or correspond to one or more software applications or programs that, when executed by a computing device, may cause the computing device to perform one or more tasks, such as the method step.

[0152] In addition, one or more of the devices described herein may transform data, physical devices, and / or representations of physical devices from one form to another. Additionally or alternatively, one or more of the modules recited herein may transform aprocessor, volatile memory, non-volatile memory, and / or any other portion of a physical computing device from one form of computing device to another form of computing device by executing on the computing device, storing data on the computing device, and / or otherwise interacting with the computing device.

[0153] The term “computer-readable medium,” as used herein, generally refers to any form of device, carrier, or medium capable of storing or carrying computer-readable instructions. Examples of computer-readable media comprise, without limitation, transmission-type media, such as carrier waves, and non-transitory-type media, such as magnetic-storage media (e.g., hard disk drives, tape drives, and floppy disks), optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks (DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-state drives and flash media), and other distribution systems.

[0154] A person of ordinary skill in the art will recognize that any process or method disclosed herein can be modified in many ways. The process parameters and sequence of the steps described and / or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed.

[0155] The various exemplary methods described and / or illustrated herein may also omit one or more of the steps described or illustrated herein or comprise additional steps in addition to those disclosed. Further, a step of any method as disclosed herein can be combined with any one or more steps of any other method as disclosed herein.

[0156] The processor as described herein can be configured to perform one or more steps of any method disclosed herein. Alternatively or in combination, the processor can be configured to combine one or more steps of one or more methods as disclosed herein.

[0157] When a feature or element is herein referred to as being "on" another feature or element, it can be directly on the other feature or element or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. It will also be understood that, when a feature or element is referred to as being "connected", "attached" or "coupled" to another feature or element, it can be directly connected, attached or coupled to the other feature or element or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected", "directly attached" or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or shown with respect to one embodiment, thefeatures and elements so described or shown can apply to other embodiments. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

[0158] Terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ".

[0159] Spatially relative terms, such as "under", "below", "lower", "over", "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is inverted, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms "upwardly", "downwardly", "vertical", "horizontal" and the like are used herein for the purpose of explanation only unless specifically indicated otherwise.

[0160] Although the terms “first” and “second” may be used herein to describe various features / elements (including steps), these features / elements should not be limited by these terms, unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another feature / element. Thus, a first feature / element discussed below could be termed a second feature / element, and similarly, a second feature / element discussed below could be termed a first feature / element without departing from the teachings of the present invention.

[0161] Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising” means various components can be co-jointly employed in the methods and articles (e.g., compositions and apparatuses including device and methods). For example, the term“comprising” will be understood to imply the inclusion of any stated elements or steps but not the exclusion of any other elements or steps.

[0162] In general, any of the apparatuses and methods described herein should be understood to be inclusive, but all or a sub-set of the components and / or steps may alternatively be exclusive and may be expressed as “consisting of’ or alternatively “consisting essentially of’ the various components, steps, sub-components or sub-steps.

[0163] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or “approximately,” even if the term does not expressly appear. The phrase “about” or “approximately” may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical values given herein should also be understood to include about or approximately that value, unless the context indicates otherwise. For example, if the value " 10" is disclosed, then "about 10" is also disclosed. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. It is also understood that when a value is disclosed that "less than or equal to" the value, "greater than or equal to the value" and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value "X" is disclosed the "less than or equal to X" as well as "greater than or equal to X" (e.g., where X is a numerical value) is also disclosed. It is also understood that the throughout the application, data is provided in a number of different formats, and that this data represents endpoints and starting points, and ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point “15” are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0164] Although various illustrative embodiments are described above, any of a number of changes may be made to various embodiments without departing from the scope of the invention as described by the claims. For example, the order in which various described method steps are performed may often be changed in alternative embodiments, and in other alternative embodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included in some embodiments and not in others. Therefore, the foregoing description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the invention as it is set forth in the claims.

[0165] The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. As mentioned, other embodiments may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is, in fact, disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.

Claims

CLAIMSWhat is claimed is:

1. A system for detecting a clot in a blood vessel, comprising: a catheter comprising a first monopolar electrode and a second monopolar electrode, the catheter configured for insertion into a blood vessel; a reference electrode; a non-transitory computer readable storage medium storing a set of instructions capable of being executed by a processor, wherein the set of instructions, when executed by the processor, causes the processor to: obtain a first impedance signal from the first monopolar electrode; obtain a second impedance signal from the second monopolar electrode; subtract the second impedance signal from the first impedance signal to forma differential impedance signal; and determine from the differential impedance signal if the first electrode is in proximity to a clot material.

2. The system of claim 1, wherein the first and second monopolar electrodes are positioned at different locations along a distal end region of the catheter.

3. The system of claim 1, wherein the reference electrode comprises a large-area patch electrode configured to be placed on the skin of a subject.

4. The system of claim 1, wherein the processor is further configured to filter the differential impedance signal to remove noise artifacts caused by respiration, heartbeat, or patient motion.

5. The system of claim 1, wherein the catheter further comprises a third monopolar electrode configured to serve as a noise-removal electrode.

6. The system of claim 1, wherein the processor is further configured to determine a type of clot material based on the magnitude or phase of the differential impedance signal.

7. The system of claim 1, wherein the catheter comprises a distal aspiration opening and the first monopolar electrode is positioned adjacent to the aspiration opening.

8. The system of claim 1, wherein the processor is further configured to control an aspiration mechanism based on the determination of clot proximity.

9. The system of claim 1, wherein the catheter includes a conductive braid or hypotube forming at least part of the reference electrode.

10. The system of claim 1, wherein the processor is further configured to compare the differential impedance signal to a threshold value to determine the presence of clot material.

11. The system of claim 1, wherein the catheter is further configured to transmit a signal between 10 MHz and 10 GHz for radiofrequency impedance sensing.

12. A clot aspiration catheter, comprising: a monopolar electrode at a distal end region, wherein a first conductive wire or trace connects the monopolar electrode with a proximal end region of the catheter; and a reference electrode along an outer length of the catheter, wherein a second conductive wire or trace connects the monopolar electrode with the proximal end of the catheter; wherein the monopolar electrode and reference electrode are configured to cooperate to provide an impedance value to a microprocessor.

13. The catheter of claim 12, wherein the reference electrode comprises a conductive braid or coil embedded in the catheter wall.

14. The catheter of claim 12, wherein the monopolar electrode is a ring electrode positioned adjacent to a distal aspiration opening.

15. The catheter of claim 12, wherein the reference electrode is a hypotube extending along a proximal portion of the catheter.

16. The catheter of claim 12, wherein the microprocessor is configured to filter the impedance value to remove physiological noise.

17. A method for detecting a blood clot in a vessel, the method comprising: inserting a catheter having one or more electrodes at a distal end region into a blood vessel, wherein each of the one or more electrodes is in electrical communication with a signal generator; transmitting, from the signal generator, a signal between 10Hz - 10GHz;transmitting, from each of the one or more electrodes, a transmitted signal from each of the one or more electrodes; detecting a magnitude and phase shift in the transmitted signal, wherein the presence of the phase shift is indicative of blood clot near the one or more electrodes.

18. The method of claim 17, wherein the signal is transmitted at a frequency between 100 MHz and 1 GHz.

19. The method of claim 17, further comprising comparing the detected phase shift to a reference signal to determine clot presence.

20. The method of claim 17, wherein the one or more electrodes are configured as radiofrequency antennas.

21. A method for extracting a clot from a blood vessel, the method comprising: detecting an impedance signal from one or more electrodes at a distal end region of a catheter; identifying, based on the impedance signal, that a clot is adjacent to the one or more electrodes and what type of clot is adjacent to the one or more electrodes by comparing the impedance signal to a threshold value; controlling the application of aspiration through the catheter based on determined type of clot.

22. The method of claim 21, wherein the type of clot is determined as acute or chronic based on the impedance signal.

23. The method of claim 21, wherein aspiration is initiated only if the impedance signal indicates an acute clot.

24. The method of claim 21, wherein the catheter further comprises a controller configured to adjust aspiration strength based on clot type.

25. An embolic filter device, the device comprising: an embolic filter basket comprising a mesh configured to capture clots and to allow blood to pass through; one or more bipolar electrode pairs configured to sense impedance on the filter basket; anda controller configured to receive an impedance signal from the one or more bipolar electrode pairs to determine the presence of clot material within the embolic filter basket.

26. The embolic filter device of claim 25, wherein the mesh comprises a plurality of conductive strands forming the bipolar electrode pairs.

27. The embolic filter device of claim 25, wherein the controller is configured to wirelessly transmit clot detection data to an external receiver.

28. The embolic filter device of claim 25, wherein the impedance signal is used to estimate the volume of clot captured in the filter basket.

29. A method of removing a clot from a blood vessel in a subject, the method comprising: advancing a catheter and an obturator extending distally from the catheter through the blood vessel; sensing an impedance signal from one or more electrodes on an outer surface of the obturator extending distally from the catheter; determining that the distal end of the obturator is adjacent to a clot material based on the impedance signal; removing the obturator from the catheter while leaving the catheter in place; and aspirating through the catheter to remove the clot material from the blood vessel.

30. The method of claim 29, wherein the obturator comprises a conical tip with multiple sensing electrodes along its slant height.

31. The method of claim 29, further comprising determining the distance between the clot and the catheter tip based on electrode position.

32. The method of claim 29, wherein the catheter is configured to aspirate only after the obturator is withdrawn.

33. A method of forming an aspiration catheter having one or more sensing electrodes, the method comprising: forming a first electrode at a distal end region of the aspiration catheter and forming conductive trace electrically coupling the first electrode to a proximal electrode pad;applying a non-conductive layer over the catheter body to electrically insulate the conductive trace; applying an outer jacket over the non-conductive layer of the catheter body; and forming a ring electrode at a proximal end region of catheter body, so that the ring electrode is in electrical communication with the proximal electrode pad.

34. The method of claim 33, wherein the conductive trace is formed by printing a conductive ink on the catheter body.

35. The method of claim 33, wherein the non-conductive layer comprises a polyether block amide material.

36. The method of claim 33, wherein the ring electrode is formed by exposing a conductive pad embedded within the catheter wall.

37. An aspiration catheter device having a distal funnel region, the device comprising: a catheter body; a distal funnel coupled to the catheter body; one or more sensing electrodes on the distal funnel; and a controller configured to receive an impedance signal from the one or more sensing electrodes to determine the presence of clot material within the distal funnel.

38. The device of claim 37, wherein the distal funnel is collapsible and self-expanding.

39. The device of claim 37, wherein the sensing electrodes are positioned on an inner surface of the funnel.

40. The device of claim 37, wherein the controller is configured to adjust funnel deployment based on detected clot presence.

41. A system for capturing clot from a blood vessel in a subject, comprising: a catheter configured for insertion into the blood vessel; a plurality of expandable tines at the distal end region of the catheter; one or more sensing electrode on each of the plurality of expandable tines; a controller configured to receive an impedance signal from the one or more sensing electrodes to determine the presence of clot material adjacent to the tines.

42. The system of claim 41, wherein the expandable tines are configured to form a reverse umbrella shape.

43. The system of claim 41, wherein the sensing electrodes are configured to detect clot in side branches of the blood vessel.

44. The system of claim 41, wherein the controller is configured to generate a visual or auditory alert upon clot detection.

45. A clot sensing device, the device comprising: an elongate body; an expandable member at a distal end of the elongate body; one or more sensing electrodes on the expandable member; a proximal handle comprising a control input configured to controllable expand or collapse the expandable member; a proximal output configured to indicate when the one or more sensing electrodes are in contact with clot.

46. The device of claim 45, wherein the expandable member comprises a plurality of splines with embedded electrodes.

47. The device of claim 45, wherein the proximal output comprises a visual indicator that changes color based on clot detection.

48. The device of claim 45, wherein the control input is configured to rotate the expandable member to assist in clot removal.