Subintimal alert during guidewire advancement

Abstract

A guidewire or other elongate member is configured for insertion into vasculature. At least one electrode is disposed at a distal end of the guidewire, and at least one electrical lead passes along or through at least a portion of the catheter and is connected with the at least one electrode. At least one electronic processor is operatively connected with the at least one electrode via the at least one electrical lead, and is programmed to, during insertion of the elongate member into the vasculature: measure an electrical parameter using the at least one electrode; detect an indication of incipient subintimal penetration of the distal end of the elongate member based on the measured electrical parameter; and output a subintimal penetration warning in response to the detection of the indication of incipient subintimal penetration.

Description

SI BIM IMAL ALERT DURING GUIDEWIRE ADVANCEMENTFIELD

[0001] The following relates generally to the intravascular catheter arts, guidewire and guidewire navigation arts, intravascular therapy arts, and related arts.BACKGROUND

[0002] Intravascular therapy (e.g., thrombectomy, atherectomy, and so forth) devices are medical devices designed to remove or modify tissue or material from inside a diseased vessel (e.g., an artery, a vein, etc.). For example, mechanical thrombectomy can treat ischemic strokes by direct removal of arterial brain clots. In intravascular procedures, a catheter carrying a removal device is inserted through the vasculature to move the catheter tip into proximity with the clot. Proper device selection and placement is important for procedure success. In a common approach, a thin catheter usually referred to as a guidewire is first inserted up to and often crossing through the clot, and the therapeutic catheter is then delivered along the guidewire.

[0003] To this end, the therapeutic catheter includes a guidewire lumen into which the proximal end of the guidewire (i.e., the end outside of the patient) is inserted, so that the therapeutic catheter can then be delivered along the guidewire. The tip of the therapeutic catheter includes one or more interventional instruments, such as a mechanical or laser cutter for performing mechanical or laser thrombectomy, an inflatable balloon to perform angioplasty, and / or so forth. The interventional instrument may sometimes also include an intravascular ultrasound (IVUS) imaging sensor to provide direct imaging of the treatment site. As the intravascular treatment may produce debris whose flow through the bloodstream may be undesirable, a stent retriever may be used for such procedures, and / or aspiration may be employed to remove the debris.

[0004] When treating atherosclerotic lesions by percutaneous interventions, guidewires are inserted into the patients’ vasculature to guide the path for subsequent devices towards and across the lesion, in order to perform the actual treatment (e.g. angioplasty or stenting). Guidewires are used in many different types of vascular interventions (coronary, peripheral, neuro) and are available with various geometries (e.g. diameters) and mechanical properties. In particular, shape and stiffness of the wire tip are relevant parameters an interventionalist must choose in the context of his / her current intention and procedure step. While stiffer wires are easierto control and navigate, floppy (i.e., less stiff) wire tips are gentler when trying to carefully spare critical structures. The choice of the wire is a compromise based on the current priority.

[0005] Depending on the lesion morphology and composition (e.g. highly stenotic, calcified, micro-calcified, or fibrous), crossing the lesion with a guidewire can be challenging. Instead of crossing in the lumen, especially stiffer wires may penetrate the intima and continue advancement subintimally (i.e. in the vessel wall). This is difficult to detect in contrasted or noncontrasted two dimensional (2D) fluoroscopic projections, where the lumen boundaries are not always visible or difficult to see due to foreshortening effects of the projective image formation or because the lesion prevents contrast inflow into the occluded lumen. Subintimal penetration can also occur when attempting to maneuver the guidewire tip through tortuous sections of the blood vessel.

[0006] If subintimal advancement goes unnoticed, (1) a seemingly successful crossing may only turn out as a failure in the next treatment step (e.g. ballooning), (2) lesion crossing may not be possible from this dead end and valuable procedure time is lost, or (3) piercing of the intima and subsequent layers of the vessel wall can turn into a more severe situation such as dissections, which require additional effort to be treated.

[0007] The following discloses certain improvements to overcome these problems and others.SUMMARY

[0008] In some embodiments disclosed herein, an intravascular device includes an elongate member configured for insertion into vasculature, at least one electrode disposed at a distal end of the elongate member, at least one electrical lead passing along or through at least a portion of the catheter and connected with the at least one electrode at the distal end of the elongate member, and at least one electronic processor operatively connected with the at least one electrode via the at least one electrical lead. The at least one electronic processor is programmed to, during insertion of the elongate member into the vasculature: measure an electrical parameter using the at least one electrode; detect an indication of incipient subintimal penetration of the distal end of the elongate member based on the measured electrical parameter; and output a subintimal penetration warning in response to the detection of the indication of incipient subintimal penetration. The elongate member may, for example, be a guidewire configured to guide an intravascular treatment catheter through the vasculature.

[0009] In some embodiments disclosed herein, an intravascular method includes: inserting an elongate member into vasculature, the elongate member having at least two electrodes disposed at a distal end of the elongate member; during the inserting, measuring an electrical parameter indicative of a medium disposed between the at least two electrodes; analyzing the electrical parameter measured during the inserting to determine an indication of subintimal penetration of the distal end of the elongate member into the vasculature; and, in response to the indication indicating that subintimal penetration of the distal end of the elongate member into the vasculature is occurring, outputting a subintimal penetration warning.

[0010] In some embodiments disclosed herein, an intravascular device includes: a guidewire configured for insertion into vasculature; at least two electrodes disposed at a distal end of the guidewire; and at least one electronic processor operatively connected with the at least two electrodes. The at least one electronic processor is programmed to, during insertion of the guidewire into the vasculature: measure an electrical parameter using the at least two electrodes; detect an indication of whether the distal end of the guidewire is in blood or in subintimal space based on the measured electrical parameter; and output the indication.

[0011] One advantage resides in automatically and immediately detecting subintimal advancement of a guidewire into tissue of a patient.

[0012] Another advantage resides in measuring an electrical parameter of a guidewire to detect incipient subintimal penetration of the guidewire.

[0013] Another advantage resides in determining a permittivity value of tissue which a guidewire contacts to detect incipient subintimal penetration of the guidewire.

[0014] Another advantage resides in detecting incipient subintimal penetration of a guidewire based on shape data of the guidewire.

[0015] Another advantage resides in detecting incipient subintimal penetration of a guidewire based on a frequency spectrum of an electrical parameter of the guidewire input into an artificial intelligence (Al) model.

[0016] A given embodiment may provide none, one, two, more, or all of the foregoing advantages, and / or may provide other advantages as will become apparent to one of ordinary skill in the art upon reading and understanding the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the disclosure.

[0018] FIGURE 1 diagrammatically illustrates an intravascular therapy device in accordance with the present disclosure.

[0019] FIGURE 2 diagrammatically illustrates a guidewire comprising a guidewire being inserted along a blood vessel, with the tip of the guidewire experiencing incipient subintimal intrusion.

[0020] FIGURE 3 diagrammatically illustrates an exemplary flowchart of operations performed with the device of FIGURE 1.

[0021] FIGURE 4 diagrammatically shows an example of detection of entry of a guidewire (e.g. guidewire) tip into subintimal tissue based on measured permittivity.DETAILED DESCRIPTION

[0022] During insertion of a guidewire, a principal risk is that the tip of the guidewire may be pushed into or even through the blood vessel wall. As the inner wall of the blood vessel is referred to as the subintimal region, this constitutes subintimal incursion. While X-ray imaging may be employed to provide visualization of the guidewire insertion in an image guided therapy (IGT) environment, the X-ray image resolution may be insufficient to provide early detection of incipient subintimal incursion.

[0023] To address this, two (or more) electrodes are disposed at or near the tip of the guidewire. As the guidewire is typically metallic, these may be in the form of electrode rings with electrical insulation disposed between the electrode and the guidewire. Electrical leads insulated with medical grade isolation material are suitably incorporated into the guidewire, or otherwise run along or within the guidewire, to provide for electrical readout of the electrodes at the proximal end of the guidewire located outside of the patient.

[0024] An electrical parameter is measured between the electrodes. The electrical parameter could be impedance or conductance, and may be converted to a metric of tissue permittivity or capacitance based on the geometry of the electrodes. The measured electrical parameter is indicative of the permittivity of the material between the electrodes. This should be blood if the tip of the guidewire is remaining within the bloodstream - but if the tip moves closeto or into contact with the subintimal layer of the blood vessel then the measured parameter will change relatively abruptly to reflect the different permittivity of the blood vessel wall or plaque, fibrous material or the like that may be in contact with the intima the blood vessel wall.

[0025] The detection of incipient subintimal incursion is thus based on a detected change of the measured electrical parameter. Various approaches for deciding when incipient subintimal incursion has occurred may be used. In a thresholding method, blood has a higher permittivity than vessel wall, so if the permittivity decreases below a lower threshold, then an alert of incipient subintimal incursion may be issued. As the blood permittivity may vary between patients or based on other factors such as injection of contrast agent, the baseline blood permittivity may be measured early in the guidewire insertion process and used to adjust the threshold. In more elaborate detection approaches, a frequency spectrum of the electrical characteristic may be measured using a frequency sweep and the entire spectrum input to an artificial neural network trained to detect incipient subintimal incursion.

[0026] If ancillary information is available, this could be used to improve the detection of incipient subintimal incursion. For example, if the distal end of the guidewire includes a fiber optic real shape (FORS) sensor then the geometry of the distal end of the guidewire can be included in the analysis, under the expectation that if the distal end of the guidewire is bending toward the blood vessel wall this increases likelihood of subintimal incursion. If there is a body electrode, then the electric metric measured between an electrode at / near the tip of the guidewire and the body electrode can provide additional input to an artificial neural network.

[0027] In a variant embodiment, the measured electrical characteristic along with such ancillary information may be input to an artificial neural network or the like to generate a likelihood of subintimal incursion, rather than a binary alert / no alert. The likelihood computation can take into account further information such as the stiffness of the distal end of the guidewire (higher stiffness increases likelihood of subintimal incursion). The likelihood of subintimal incursion can be displayed on the IGT display or a display in an interventional room where the imaging is occurring to inform the surgeon of the risk of subintimal incursion, and this could for example turn red and / or flash if the likelihood of subintimal incursion is calculated to be above a threshold. In a further variant, the likelihood of subintimal incursion can be tracked over the course of the insertion and later used to assess the surgeon’s performance, hence providing a training tool.

[0028] The disclosed system can be used with guidewires since they are initially inserted and most likely to be pushed into or through a blood vessel wall. By contrast, a therapeutic catheter is usually inserted along the guidewire, and due to the guidance of the previously inserted guidewire subintimal penetration by the therapeutic catheter is substantially less likely. However, the disclosed system could be applied to other types of catheters, such as microcatheters that may be extended in an unguided fashion (that is, not guided along a previously inserted guidewire) to perform a procedure such as aneurysm coiling.

[0029] With reference to FIGURE 1, an illustrative intravascular device 10 is diagrammatically shown. As shown in FIGURE 1, the intravascular device 10 is insertable into a blood vessel V for treating an occlusion O (or a clot, or a lesion, and so forth) in the blood vessel V. The intravascular therapy device 10 includes, for example, a catheter 12 that is configured for insertion into vasculature. In some embodiments, the catheter 12 is an elongate member such as a guidewire configured to be inserted into the blood vessel V, usually past the occlusion O, to subsequently guide an intravascular treatment catheter (not shown) through the vasculature. In some illustrative embodiments disclosed herein, the elongate member 12 is a guidewire 12, but more generally the elongate member 12 could be another type of flexible intravascular instrument designed for insertion through potentially tortuous vasculature, such as a microcatheter as another illustrative example. The guidewire 12 in some nonlimiting illustrative embodiments has a diameter of 1 mm or less. As one specific nonlimiting illustrative example, the guidewire 12 may be a standard coronary guidewire with a 0.36 mm diameter. The guidewire is typically relatively long and flexible, e.g. having a length on the order of 175-330 centimeters in some nonlimiting illustrative examples. The guidewire 12 can be electrically conductive, or in other embodiments may be electrically insulating. As another example, the guidewire 12 could have a stainless steel or nitinol central shaft or core surrounded by coils or polymers and an outer biocompatible surface coating. The distal tip of the guidewire 12 may have a different construction, such as comprising a platinum or tungsten alloy, and optionally may have a tapered end, a built-in bend, and / or other features.

[0030] With continuing reference to FIGURE 1 and with further reference to FIGURE 2, a larger portion of the guidewire 12 is shown in FIGURE 2 being advanced by an operator (e.g., surgeon) in the indicated direction of guidewire tip advancement. As shown in FIGURE 2, the guidewire 12 is disposed in and traveling through a lumen Lv of the blood vessel V; however, atip 13 of the guidewire 12 is experiencing incipient subintimal intrusion as it is beginning to penetrate the inner lumen wall of the blood vessel V.

[0031] With returning reference to FIGURE 1, at least one electrode 14 is disposed at the distal end 13 of the guidewire 12. As shown in FIGURE 1, two electrodes 14, 14' are shown. The first electrode 14 can comprise an electrically conductive ring 14 and an electrical insulation layer16 (i.e., foam) disposed between the ring 15 and the guidewire 12. The second electrode 14' can include a ring 15' and an electrical insulation layer 16' (e.g., foam) disposed between the ring 15' and the guidewire 12. The rings 14, 14' form a pair of electrodes, and an electrical property is to be measured between the ring electrodes 14 and 14’. Note that FIGURE 1 shows the distal tip 13 of the guidewire 12 in a side sectional view, and the electrode rings 14, 14’ and annular insulating layer 16 are being intersected by the section plane. Moreover, while ring electrodes 14 and 14’ are shown, the electrodes could have other geometries, e.g. two circular electrodes disposed on the insulation layer 16’.

[0032] At least one electrical lead 17 passes along or through at least a portion of the guidewire 12. As shown in FIGURE 1, two electrical leads 17, 17' are shown. The electrical leads 17, 17' are connected with a corresponding electrode 14, 14'. Note that the electrical leads17 and 17’ are indicated diagrammatically, and in implementation will typically be electrical wires or conductors disposed along or inside and extending along the guidewire 12. To accommodate the electrical leads 17, 17', the guidewire 12 can be any suitable guidewire (e.g., an Omniwire pressure guide wire, available from Koninklijke Philips N.V., Eindhoven, the Netherlands). In such embodiments, the electrical leads 17, 17' run along a first side of the guidewire 12 and connect to the electrodes 14, 14' on an opposing second side of the guidewire 12. If the guidewire 12 or the portion thereof contacting the leads 17, 17’ is electrically conductive, then the leads 17, 17’ may be coated with electrical insulation to avoid electrical shorting to the guidewire 12. In some examples, the electrical leads 17, 17' are attached to the guidewire 12, and the electrodes 14, 14' are connected to an electronic processing device 18 via the electrical leads 17, 17'.

[0033] FIGURE 1 further shows the electronic processing device 18, such as a workstation computer, an image-guided therapy (IGT) controller, or more generally a computer which can be used to determine incipient subintimal penetration of the guidewire 12. The electronic processing device 18 may also include a server computer or a plurality of server computers, e.g., interconnected to form a server cluster, cloud computing resource, or so forth, to perform morecomplex computational tasks. The workstation 18 includes typical components, such as an electronic processor 20 (e.g., a microprocessor), at least one user input device (e.g., a mouse, a keyboard, a trackball, and / or the like) 22, and a display device 24 (e.g., an LCD display, plasma display, cathode ray tube display, and / or so forth). In some embodiments, the display device 24 can be a separate component from the electronic processing device 18 or may include two or more display devices.

[0034] The electronic processor 20 is operatively connected with one or more non- transitory storage media 26. The non-transitory storage media 26 may, by way of non-limiting illustrative example, include one or more of a magnetic disk, RAID, or other magnetic storage medium; a solid-state drive, flash drive, electronically erasable read-only memory (EEROM) or other electronic memory; an optical disk or other optical storage; various combinations thereof; or so forth; and may be for example a network storage, an internal hard drive of the electronic processing device 18, various combinations thereof, or so forth. It is to be understood that any reference to a non-transitory medium or media 26 herein is to be broadly construed as encompassing a single medium or multiple media of the same or different types. Likewise, the electronic processor 20 may be embodied as a single electronic processor or as two or more electronic processors. The non-transitory storage media 26 stores instructions executable by the at least one electronic processor 20. The instructions include instructions to generate a visualization of a graphical user interface (GUI) 28 for display on the display device 24.

[0035] The at least one electronic processor 20 is configured as described above to perform an intravascular method or process 100. The non-transitory storage medium 26 stores instructions which are readable and executable by the at least one electronic processor 20 to perform disclosed operations including performing the intravascular method or process 100. In some examples, the method 100 may be performed at least in part by cloud processing.

[0036] Referring to FIGURE 3, and with continuing reference to FIGURE 1 , an illustrative embodiment of the intravascular method 100 is diagrammatically shown as a flowchart. To begin the method 100, the guidewire 12 is inserted into the blood vessel V adjacent the occlusion O. During insertion of the guidewire 12, at an operation 102, an electrical parameter of vasculature of the patient is measured using the electrodes 14, 14' The electrical parameter is indicative of a medium disposed between the at least two electrodes 14, 14'. The electrical parameter of the atleast one electrode electrodes 14, 14 comprises impedance or conductance. In some examples, the impedance or conductance is converted to a permittivity value.

[0037] At an operation 104, an indication of incipient subintimal penetration of the distal end of the guidewire 12 is detected based on the measured electrical parameter by analyzing the electrical parameter measured during the inserting to determine an indication of subintimal penetration of the distal end of the elongate member 12 into the vasculature. For example, the indication of incipient subintimal penetration is detected based on the permittivity value and / or a change in the permittivity value over time.

[0038] With brief reference to FIGURE 4, an example of how the measured permittivity as a function of time during advancement of the guidewire can be used to detect incipient subintimal penetration. As seen in FIGURE 4, while the guidewire tip remains in the bloodstream (indicated in FIGURE 4 as “guidewire tip in blood”), the measured permittivity is relatively high. The average blood permittivity is shown in FIGURE 4 as Sbiood- At a time Tp the tip begins subintimal penetration. Due to a lower permittivity of the blood vessel wall tissue (indicated in FIGURE 4 as tissue) compared with blood permittivity Sbioocb the measured permittivity rapidly decreases as the guidewire tip enters into the subintimal tissue , as seen in the right portion of the graph of FIGURE 4 labeled “Guidewire tip in tissue”. Because the electrodes 14 and 14’ are at the guidewire tip 13 (see FIGURE 1), the subintimal penetration is quickly detected. For example, if the tip of the elongate member 12 is being advanced at a rate of 10 mm / s and the electrodes 14 and 14’ are spaced apart by 1 mm (by way of a nonlimiting illustrative example), then both electrodes 14 and 14’ will be fully within the subintimal tissue in 0.1 seconds. In some embodiments, the detecting operation 104 is performed by calibrating a baseline value of the electrical parameter corresponding to the distal tip of the elongate member 12 being immersed in blood contained in the vasculature (that is, corresponding to Sbiood) based on the electrical parameter measured over a calibration time interval. After the calibration time interval, the indication of incipient subintimal penetration is determined as a change in the electrical parameter from the baseline value, e.g. a decrease as shown in FIGURE 4. It should be noted that while FIGURE 4 plots measured “permittivity”, more typically the measured electrical parameter will be an electrical parameter such as impedance, capacitance, or the like, which correlates with the blood or tissue permittivity but is not equal to it.

[0039] In other embodiments, the detecting operation 104 is performed by generating a frequency spectrum of the electrical parameter, and determining the indication of incipient subintimal penetration based on the frequency spectrum and / or a change in the frequency spectrum over time.

[0040] In some embodiments, the detecting operation 104 is performed by inputting the electrical parameter measured as a function of time and / or a frequency spectrum generated from the electrical parameter measured as a function of time to an artificial neural network (ANN) 30 trained to detect incipient subintimal penetration. The ANN is implemented in the electronic processing device 18.

[0041] In some embodiments, the device 10 further includes a sensor 32, such as or a fiber optic real shape sensor. The sensor 32 is disposed inside the guidewire 12 and is configured to measure shape data related to a shape of the distal end of the guidewire 12. The detecting operation 104 then includes determining the indication of incipient subintimal penetration further based on the shape data measured by the sensor 32.

[0042] At an operation 106, in response to the indication indicating that subintimal penetration of the distal end of the elongate member 12 into the vasculature is occurring, a subintimal penetration warning 36 in response to the detection of the indication of incipient subintimal penetration can be output, for example on the GUI 28 of the display device 24. The penetration warning 36 is a human-perceptible (e.g. audible and / or visual) indicator of incipient subintimal penetration that can be implemented in various ways. For example, if the representation shown in FIGURE 2 is a display of an image of the guidewire 12 and blood vessel V captured by an external image-guided therapy (IGT) imaging device such as a C-arm X-ray imaging device, then the penetration warning 36 can be implemented as a flashing indicator 36 (see FIGURE 2) that is presented proximate to the location of the guidewire tip 13 and optionally on a side of the displayed blood vessel 12 where the incipient subintimal penetration is occurring, as shown in FIGURE 2. In another embodiment, the penetration warning 36 could be an audible signal emitted by a loudspeaker of the electronic processing device 18. In another embodiment, the penetration warning 36 could be a textual warning (e.g. “WARNING: SUBINTIMAL PENETRATION DETECTED!”) displayed on the display 24 of the electronic processing device 18. Various combinations are contemplated, such as providing both audible and visual warning.

[0043] In some examples, bending data of the guidewire 12 can be obtained by X-ray imaging of the guidewire 12 to compensate for foreshortening of the guidewire 12. To do so, at an optional operation 108, an imaging and / or treatment catheter (not shown) and / or treatment device (not shown) at an end thereof having at least one imaging device is inserted (after the inserting of the guidewire 12) along the inserted guidewire 12 to position the at least one imaging and / or treatment device at an intravascular target site. Imaging 108 and / or treatment 110 of the intravascular target site using the at least one imaging and / or treatment device is then performed.

[0044] In the illustrative examples, the elongate member 12 is a guidewire. In other examples, the elongate member 12 comprises another type of intravascular instrument, such as a microcatheter configured to perform an intravascular therapy. In this case, the microcatheter itself performs the treatment 110.EXAMPLE

[0045] Gradients in the electrical field, i.e. the impedance (permittivity & capacitance) will change depending on the material surrounding the wire tip. This is typically blood, but sub- intimally could change into more solid fibrous, fatty, or calcified tissue components. This changes over time & wire advancement are analyzed by the electronic processing device 18. This may comprise but is not limited to simple thresholding to separate out abnormal signals from expected signals within the lumen (may include per patient calibration at the beginning of the advancement), more advance signal processing such as filter bank analyses, or machine / deep learning models trained on historical data.

[0046] The latter may also distinguish between different materials, and can therefore issue warnings and different risk levels based on the penetration path, but also materials (e.g. if a fatty region has been entered by piercing a thin fiber cap and there is immediate danger of a thrombus or plaque rupture). As an extension the dielectric sensing can make use of multiple frequency components for the electric field generated, to not only extract point estimates of permittivity, capacitance or impedance, but get a more informative signature for each material.

[0047] The disclosed device 10 will issue warnings / alerts via the GUI 28 if substantial changes in the measured electrical field properties occur.

[0048] The electronic processing device 18 may also further interpret the material close by (e.g. microcalcifications) or penetrated and make use of the wire parameters to base potential risks on prior knowledge (e.g. a stiffer wire is more likely to penetrate the wall)

[0049] The GUI 28 may also accumulate risk or close-to-risk events during the intervention and may suggest considering changing the wire device to the clinician based on a database of wire with their properties.

[0050] Dielectric spectroscopy measures a real and imaginary permittivity part s’ and where the second is related to conductivity. a ’ is typically given in diagrams relative to that in air or vacuum. Here there are certain dispersion ranges in the spectrum, where s ’ drops due to different physical phenomena (denoted alpha (a), beta (|3), gamma (y), delta (5)), which are typically measured in kHz, low MHz and / or low GHz ranges. For each of these different types of dispersion ranges a number of descriptive features can be defined and extracted from the spectrum so as to characterize the relevant information from each range in the spectrum in a smaller number of informative features. As an example, the center frequency fcenter of the respective dispersion range, its frequency extent Af and drop of permittivity As. For each of these may be distinct for different biological tissues and hence be used to differentiate between them. As an example, there is no substantial dispersion for blood in the kHz (a) range, while there is significant drop in permittivity for fat or fibrous muscle tissue in the same range. Similar differences can be observed for the other dispersion ranges (see, e.g., Gabriel et al., The Dielectric Properties of Biological tissues: III. Parametric models for the dielectric spectrum of tissues. Phys. Med. Biol. 41 (1996) 2271-2293; Escalante-Martinez et al., “Fractional Derivatives modeling dielectric properties of biological tissue” (2018). 1-3. 10.1109 / INTERCON.2018.8526460). Thus, for example, an indication of incipient subintimal penetration can be determined based on detection of a change in permittivity in the alpha and beta dispersion over an analyzed frequency range of the frequency spectrum over time which is indicative of incipient penetration of the distal end of the elongate member 12 into tissue which has a increase (alpha) or decrease (beta) of permittivity in the analyzed frequency range than blood.

[0051] In one approach, N number of measurements (e.g. 4, alpha, beta, gamma, delta) delta eps ’ of the dispersion intervals are carried out and tracked the change over time to detect when entering other tissue. In another approach, a parametric model can be fit into the spectrum (see, e.g., Gabriel S, Lau RW, Gabriel C. The dielectric properties of biological tissues: III.Parametric models for the dielectric spectrum of tissues. Phys Med Biol. 1996 Nov;41(ll):2271- 93. doi: 10.1088 / 0031-9155 / 41 / 11 / 003. PMID: 8938026), and be used to track its parameters over time. In a third approach, the ANN 30 can be trained to classify the difference spectrum between that of blood (calibration reference) and the currently measured one into e.g. one of a plurality of classes such as blood, fibrous, chronic total occlusion (CTO), and others (fatty, calcified). The classification is done by assigning a probability estimate to each of these predefined classes: Outputs may even indicate intermediate states when the vessel wall is approached and not the entire electrical field is covering the more insulating medium. The implementation and design of all three options is data-driven by design and calibrated on-the-fly when the wire enters the vessel in the blood stream. Additional factors such as temperature or hematocrit may also impact the measurement and may vary by patient or even medication.

[0052] In some examples, the measured and processed frequency information can be differently used in the interventional context. In a first use case, a user may interpret the penetration warning 36 as a warning that the guidewire 12 is unintendedly leaving the lumen of the vessel (i.e. blood stream) and entering subintimal space with the guidewire 12. In a second use case the user can use the information for navigating the guidewire 12, e.g. when crossing a CTO. Here, he may want to leave the vascular lumen intentionally, entering a thrombus or clot blocking the vessel before he re-enters the lumen distally leaving the CTO behind. The guidewire 12 can detect entering the subintimal space as the plaque component constellation (i.e., fibrous, fatty, calcified) would differ from clotted blood. Depending on whether entering these different areas of the diseased vascular anatomy was the intended navigation or not, the user may correct maneuvering of the guidewire 12.

[0053] In some embodiments, a re-entry device (not shown) can be used to retrieve the guidewire 12 from the vessel V after bypassing a lesion (e.g. a CTO) via the subintimal space. Such re-entry devices can include a Philips Pioneer Plus (available from Koninklijke Philips N.V., Eindhoven, the Netherlands), or any other suitable re-entry device. In such embodiments, the guidewire 12 via the electrodes 14, 14' can then be used to make sure the guidewire 12 is in the subintimal space. The re-entry device can be advanced over the guidewire 12 into the subintimal space past the lesion. A puncture will then be made back into the true vascular lumen (behind the lesion) after which the guidewire 12 can be advance into this lumen to verify that a re-entry in the true vascular lumen is made. Hence, more generally, the disclosed approach can be used to detectan indication of whether the distal end of the guidewire (or other elongate member) 12 is in blood or in subintimal space based on the measured electrical parameter. The approaches can thus be used to detect subintimal penetration and subsequent re-entry of the guidewire tip into blood.

[0054] The disclosure has been described with reference to the preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

CLAIMS:

1. An intravascular device (10), comprising: an elongate member (12) configured for insertion into vasculature; at least one electrode (14, 14') disposed at a distal end of the elongate member; at least one electrical lead (17, 17') passing along or through at least a portion of the catheter and connected with the at least one electrode at the distal end of the elongate member; and at least one electronic processor (20) operatively connected with the at least one electrode via the at least one electrical lead, the at least one electronic processor programmed to, during insertion of the elongate member into the vasculature: measure an electrical parameter using the at least one electrode; detect an indication of incipient subintimal penetration of the distal end of the elongate member based on the measured electrical parameter; and output a subintimal penetration warning (36) in response to the detection of the indication of incipient subintimal penetration.

2. The intravascular therapy device (10) of claim 1, wherein the elongate member (12) is a guidewire configured to guide an intravascular treatment catheter through the vasculature.

3. The intravascular therapy device (10) of claim 2, wherein the at least one electrical lead (17, 17') is attached to the guidewire.

4. The intravascular therapy device (10) of any one of claims 1-3, wherein the at least one electrodes (14, 14 ) comprises: a pair of rings (15, 15') forming a pair of electrodes; and an insulation layer (16, 16') disposed between the rings and the elongate member5. The intravascular therapy device (10) of any one of claims 1-4, wherein the electrical parameter of the at least one electrode (14, 14') comprises impedance or conductance.

6. The intravascular therapy device (10) of claim 5, wherein the at least one electronic processor (20) is further programmed to: convert the impedance or conductance to a permittivity value; and detect the indication of incipient subintimal penetration based on the permittivity value and / or a change in the permittivity value over time.

7. The intravascular therapy device (10) of any one of claims 1-6, wherein the at least one electronic processor (20) is programmed to detect the indication of incipient subintimal penetration of the distal end of the elongate member (12) by operations including: calibrating a baseline value of the electrical parameter corresponding to the distal tip of the elongate member being immersed in blood contained in the vasculature based on the electrical parameter measured over a calibration time interval; and after the calibration time interval, determining the indication of incipient subintimal penetration as a change in the electrical parameter from the baseline value.

8. The intravascular therapy device (10) of any one of claims 1-7, wherein the at least one electronic processor (20) is programmed to detect the indication of incipient subintimal penetration of the distal end of the elongate member by operations including: generating a frequency spectrum of the electrical parameter; and determining the indication of incipient subintimal penetration based on the frequency spectrum and / or a change in the frequency spectrum over time.

9. The intravascular therapy device (10) of claim 8, wherein the indication of incipient subintimal penetration is determined based on detection of a change in permittivity over an analyzed frequency range of the frequency spectrum over time which is indicative of incipient penetration of the distal end of the elongate member (12) into tissue which has different dispersion in the analyzed frequency range than blood.

10. The intravascular therapy device (10) of any one of claims 1-9, further including: a sensor (32) disposed at the distal end of the elongate member (12) and configured to measure shape data related to a shape of the distal end of the elongate member; and wherein the at least one electronic processor (20) is programmed to determine the indication of incipient subintimal penetration further based on the shape data measured by the sensor.

11. The intravascular therapy device (10) of any one of claims 1-10, wherein the at least one electronic processor (20) is programmed to determine the indication of incipient subintimal penetration by operations including: inputting the electrical parameter measured as a function of time and / or a frequency spectrum generated from the electrical parameter measured as a function of time to an artificial neural network (ANN) (30) trained to detect incipient subintimal penetration.

12. An intravascular method (100), comprising: inserting an elongate member (12) into vasculature, the elongate member having at least two electrodes (14, 14') disposed at a distal end of the elongate member; during the inserting, measuring an electrical parameter indicative of a medium disposed between the at least two electrodes; analyzing the electrical parameter measured during the inserting to determine an indication of subintimal penetration of the distal end of the elongate member into the vasculature; and in response to the indication indicating that subintimal penetration of the distal end of the elongate member into the vasculature is occurring, outputting a subintimal penetration warning (36).

13. The intravascular method (100) of claim 12, wherein the elongate member (12) comprises a guidewire and the method further comprises: after the inserting of the guidewire, inserting an imaging and / or treatment catheter having at least one imaging and / or treatment device at an end thereof along the inserted guidewire to position the at least one imaging and / or treatment device at an intravascular target site; and performing imaging and / or treatment of the intravascular target site using the at least oneimaging and / or treatment device.

14. The intravascular method (100) of claim 12, wherein the elongate member (12) comprises a microcatheter configured to perform an intravascular therapy and the method further comprises: during and / or after the inserting, performing an intravascular therapy using the microcatheter.

15. An intravascular device (10), comprising: a guidewire (12) configured for insertion into vasculature; at least two electrodes (14, 14') disposed at a distal end of the guidewire; and at least one electronic processor (20) operatively connected with the at least two electrodes and programmed to, during insertion of the guidewire into the vasculature: measure an electrical parameter using the at least two electrodes; detect an indication of whether the distal end of the guidewire is in blood or in subintimal space based on the measured electrical parameter; and output the indication.

16. The intravascular device (10), wherein the guidewire has a diameter of 1 mm or less.

17. The intravascular therapy device (10) of either one of claims 15 and 16, wherein the guidewire (12) is electrically conductive, and each electrode comprises a conductive ring (15, 15') encircling the distal end of the guidewire and electrically insulated from the electrically conductive guidewire by an electrical insulator (16, 16') disposed between the ring and the distal end of the guidewire.

18. The intravascular therapy device (10) of any one of claims 15-17, wherein the electrical parameter of the at least two electrodes (14, 14') comprises permittivity.

19. The intravascular therapy device (10) of any one of claims 15-18, wherein the at least one electronic processor (20) is programmed to detect the indication of incipient subintimalpenetration of the distal end of the guidewire by operations including: calibrating a baseline value of the electrical parameter corresponding to the distal tip of the guidewire being immersed in blood contained in the vasculature based on the electrical parameter measured over a calibration time interval; and after the calibration time interval, determining the indication of incipient subintimal penetration into the subintimal space as a change in the electrical parameter from the baseline value.

20. The intravascular therapy device (10) of any one of claims 15-19, further including: a sensor (32) disposed at the distal end of the guidewire (12) and configured to measure shape data related to a shape of the distal end of the guidewire; and / wherein the at least one electronic processor (20) is programmed to determine the indication of whether the distal end of the guidewire is in blood or in subintimal space further based on the shape data measured by the sensor.

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