Self-tracting occlusion-crossing catheter with controlled steering based on impedance sensing

Abstract

The endovascular treatment device 10 includes a catheter 12 and a plurality of parallel cutting instruments 14, 16, 18 disposed at at least the distal end of the catheter. Each cutting instrument is configured to affect a portion of a clot disposed within a blood vessel through which the catheter is advanced. Each cutting instrument is independently advanceable into the clot.

Description

[Technical Field]

[0001] The following relates generally to catheter, mechanical thrombectomy, spectroscopy, and related technologies. [Background technology]

[0002] A chronic total occlusion (CTO) is a complete blockage of a blood vessel. To treat such a CTO (or other near-total occlusion) in a typical endovascular treatment workflow, a guidewire is first inserted into the blood vessel and maneuvered to pass through the occlusion (also referred to herein as a blood clot). After passing the occlusion, an interventional catheter (i.e., a balloon / stent device, etc.) is inserted along the guidewire to access the CTO and perform treatment. Because the guidewire is flexible, passing the CTO is difficult and sometimes impossible due to guidewire buckling issues. The problem is that the guidewire is not stiff enough to push through the CTO without buckling. Furthermore, the guidewire must remain within the blood vessel and therefore requires maneuverability while advancing through the CTO; otherwise, the guidewire may accidentally push into or penetrate the vessel wall, potentially causing undesired damage or rupture of the vessel. Sensing is useful to provide feedback to know whether the guidewire or catheter is inside the (occluded) lumen, inside the vascular tissue, or has completely perforated the vessel wall.

[0003] One way to obtain such feedback is by employing interventional imaging using modalities such as computed tomography (CT) or another x-ray imaging modality, or ultrasound imaging. However, while these imaging techniques can be useful for tracking the progress of a guidewire to the occlusion, they have limited spatial resolution and contrast and therefore may not accurately detect vascular penetration when the operator attempts to insert the tip of the guidewire into the occlusion. An experienced operator may be able to determine that tissue has been penetrated by manual tactile feedback as the guidewire is pushed into the occlusion area and / or by monitoring aspirated material if suction is performed during passage, but these, too, can be inaccurate and misleading to the operator. Summary of the Invention [Problem to be solved by the invention]

[0004] The following discloses specific improvements to overcome these and other problems. [Means for solving the problem]

[0005] In some embodiments disclosed herein, an endovascular treatment device includes a catheter and a plurality of parallel cutting instruments disposed at at least a distal end of the catheter, each configured to act on a portion of a clot disposed within a blood vessel through which the catheter is advanced, each cutting instrument being independently advanceable within the clot.

[0006] In some embodiments disclosed herein, an endovascular treatment device includes a flexible catheter including at least three parallel flexible sub-catheters, each having a tip configured to act on a portion of a clot, each sub-catheter being independently movable relative to the other sub-catheters of the at least three parallel flexible sub-catheters.

[0007] In some embodiments disclosed herein, an occlusion-crossing method includes performing an electrospectroscopy measurement on at least one cutting instrument positioned at the distal end of the catheter to act on a portion of a blood clot located within a blood vessel through which the catheter is advanced, and determining, based on the electrospectroscopy measurement, a type of tissue against which the at least one cutting instrument is to act.

[0008] One advantage is that it provides feedback to correct the advancement of the catheter into the occluded area.

[0009] Another advantage resides in providing a catheter that provides a traction component during passage of the occlusion to improve the ability and efficiency of penetration through the occlusion.

[0010] Another advantage resides in providing a catheter with multiple cutting devices (eg, sub-catheters) for affecting occlusions.

[0011] Another advantage resides in measuring the impedance of the catheter's cutting tool to determine the type of tissue the catheter is acting on.

[0012] Another advantage is that it provides an optical measurement of the type of tissue the catheter is acting on.

[0013] A given embodiment may provide none, one, two, more, or all of the aforementioned advantages, and / or other advantages that will become apparent to those skilled in the art upon reading and understanding this disclosure.

[0014] 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 preferred embodiments and are not to be construed as limiting the disclosure. [Brief explanation of the drawings]

[0015] [Figure 1] 1 illustrates an embodiment of an endovascular treatment device according to the present disclosure. [Figure 2] 1 illustrates an embodiment of an endovascular treatment device according to the present disclosure. [Figure 3] 2 illustrates a method of performing an endovascular treatment using the device of FIG. 1; DETAILED DESCRIPTION OF THE INVENTION

[0016] In embodiments disclosed herein, the catheter (e.g., in some embodiments, a guidewire) provides a traction force to assist in penetrating the occlusion to achieve passage. This traction force can advantageously reduce or eliminate the use of a pushing force to achieve passage. As previously discussed, attempting to pass an occlusion by pushing a catheter or guidewire through the occlusion can result in buckling of the catheter and inability or difficulty in achieving passage. This is because the pushing force is applied to the proximal end of the catheter, i.e., the end located outside the patient's vasculature, and is transmitted along the entire length of the catheter positioned in the vasculature to reach the distal end where the pushing force is applied to the occlusion. Because the catheter is flexible to accommodate the tortuous curves of the vasculature through which it is passed, the transmitted pushing force can lead to buckling of the catheter. In contrast, the catheters disclosed herein employ multiple parallel cutting instruments located at at least the distal end of the catheter (in some embodiments, with sub-catheters extending the length of the catheter or other catheters). Each of the parallel cutting instruments can move or slide relative to the other cutting instruments. When there are at least three cutting instruments, the one currently moving cutting instrument generates less frictional force than the remaining two (or more) currently stationary cutting instruments. See Scali et al., "Ovipositor-inspired steerable needle: design and preliminary experimental evaluation," 2018 Bioinspir. 9Biomim. 13 016006. As a result, the stationary cutting instruments provide frictional forces that tend to hold the catheter tip in a fixed position to allow the moving cutting instruments to advance into the clot. This process is repeated cyclically for each cutting instrument in turn, advancing the catheter tip as a whole through the clot and thereby achieving (or at least assisting in) passage of the clot.In various embodiments, the cyclical advancement of each cutting instrument in sequence can be achieved manually (e.g., by a human operator sequentially pushing each cutting instrument with its sub-catheter in sequence) or by a mechanical or electromechanical mechanism.

[0017] A further advantage of the exemplary catheters disclosed herein is that the cutting instruments provide a platform for performing tissue measurements. In one approach, each cutting instrument is conductive and used as an electrode in an impedance measurement (or other type of electrical property measurement). For example, spectral impedance measurements between a pair of cutting instruments can provide a tissue signature for identifying the type of tissue (e.g., blood, clot tissue, vessel wall, etc.) located between the pair of cutting instruments. See, for example, Gabriel et al., "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues," Phys. Med. Biol., vol. 41, pp. 2271-93 (1996); Ambrogio et al., "Investigation of Blood Coagulation Using Impedance Spectroscopy: Toward Innovative Biomarkers to Assess Fibrinogenesis and Clot Retraction," Biomedicines 2022, 10, 1833.

[0018] In another approach, the ablation instruments have sub-catheters, each containing one or more optical fibers (or waveguides) for injecting light into the distal tip of the sub-catheter. By arranging the fiber optic ends of adjacent ablation instruments facing each other, light can be transmitted through the gap between the adjacent ablation instruments to perform optical measurements of the tissue disposed between the instruments. This allows optical spectroscopy to be performed to provide a tissue signature for identifying the type of tissue (e.g., blood, clot tissue, vessel wall, etc.) disposed between the pair of ablation instruments. See, for example, Skyrman et al., "Clot composition characterization using diffuse reflectance spectroscopy in acute ischemic stroke," Biomedical Optics Express, vol. 13, no. 6 (June 2022); Skyrman et al., "Identifying clot composition using intravascular diffuse reflectance spectroscopy in a porcine model of endovascular thrombectomy," J. NeuroIntervent Surg, April 2021. In some embodiments, a pair (or more) of fibers can be included. One fiber can be used to emit light and another fiber can be used to receive light.

[0019] Although primarily described in terms of spectral impedance measurements, the systems and methods described herein may also include optical sensing (optical spectroscopy, fluorescence spectroscopy, Raman spectroscopy, optical coherence tomography, etc.) requiring optical fibers, pressure sensors within sub-catheters (i.e., measuring tissue resistance), acoustic sensors (i.e., measuring acoustic properties), etc. Other types of sensors, including cutting instruments, are also contemplated for sensing the type of tissue upon which the cutting instrument is acted upon.

[0020] Referring to FIG. 1 , an endovascular treatment device 10 for treating a blood clot C or occlusion (e.g., a CTO or near-total occlusion) of a blood vessel V is illustrated. As used herein, “blood clot” and “occlusion” are synonymous and refer to a complete or near-complete blockage of blood flow through a blood vessel. The treatment device 10 includes a flexible catheter (or guidewire) 12 that is advanced into the blood vessel V and adjacent to the clot C. The flexible catheter 12 is flexible in the sense that the catheter 12 can be pushed through a tortuous blood vessel path to move its distal end toward the clot C, and the flexible catheter 12 bends or flexes during the insertion process to conform to the tortuous blood vessel path. The catheter 12 may, for example, be a guidewire in some embodiments. In the first embodiment shown in FIG. 1 , the multiple parallel cutting instruments 14, 16, 18 in this embodiment comprise sub-catheters of the catheter 12 that extend to the distal end of the catheter 12 (i.e., adjacent to or near the clot C). 1 shows three cutting instruments 14, 16, 18 parallel to one another, any suitable number of at least three cutting instruments can be implemented. Each cutting instrument 14, 16, 18 is independently advanceable into the clot C. Each cutting instrument 14, 16, 18 is configured to act on a portion of the clot C, for example, by having a tapered or pointed tip. The cutting instruments 14, 16, 18 of the catheter 12 can be used to create a traction force that pulls the catheter 12 through the clot C, thereby passing the clot C.

[0021] After catheter 12 passes through clot C, various types of treatments can be applied. In some embodiments, the exemplary catheter 12 is a guidewire. In such embodiments, after guidewire 12 passes through clot 12, a second catheter (not shown) is inserted along with guidewire 12 by inserting the proximal end of guidewire 12 into the lumen of the second catheter such that guidewire 12 can guide the distal end of the second catheter up to (possibly over a short distance) clot C. The second catheter suitably carries an angioplasty balloon, an expandable stent, a mechanical or laser cutter, and / or other treatment components for treating clot C by angioplasty, stenting, thrombectomy, etc.

[0022] In other contemplated embodiments, the illustrated catheter 12 may be a second catheter inserted along a (significantly smaller diameter) guidewire previously inserted through the guidewire lumen 21. In this case, the illustrated catheter 12 would suitably carry a therapeutic component, while the guidewire would be used both to pass through the clot C as disclosed herein and to carry a therapeutic component (not shown) for treating the clot C.

[0023] The sub-catheters 14, 16, 18 of the catheter 12 are held together in a parallel bundle by a suitable retention mechanism 19. In an illustrative example, this retention mechanism comprises a carrier catheter 19 having a lumen within which the sub-catheters 14, 16, 18 are disposed. In another contemplated embodiment, the retention mechanism may include interlocking mechanisms incorporated into the sub-catheters 14, 16, 18 themselves, such as mating longitudinal keyed edges and slots (not shown) on the sub-catheters 14, 16, 18 that engage to lock the sub-catheters 14, 16, 18 in a parallel arrangement with one another. In either case, the retention mechanism 19 allows the sub-catheters 14, 16, 18 to move or slide relative to one another, and more specifically, allows one of the sub-catheters (e.g., sub-catheter 18) to move or slide at any given time, while the other sub-catheters (e.g., sub-catheters 14, 16) may or may not be fixed. Such movement can be cyclical, such as by sequentially advancing each sub-catheter in sequence, e.g., by advancing and then retracting sub-catheter 18, then advancing and then retracting sub-catheter 14, then advancing and then retracting sub-catheter 16, then advancing and then retracting sub-catheter 18, etc. In another example, each of sub-catheters 14, 16, and 18 can be advanced, and then retention mechanism 19 can be pulled forward to retract sub-catheters 14, 16, and 18. This process can be repeated as needed. In another example, catheter 12 can be steered so that each of sub-catheters 14, 16, and 18 can be advanced in a different motion. These are merely examples and should not be construed as limiting.

[0024] For purposes of illustration, as shown in FIG. 1 , a first cutting instrument 14 is advanced out of the catheter 12 and impinges on a portion of the clot C. A second cutting instrument 16 is partially advanced out of the catheter 12. A third cutting instrument 18 is shown disposed within the catheter 12. Each of the cutting instruments 14, 16, 18 includes serrations 20, such as illustrative serrations or saw-tooth structures 20, configured to impinge on a portion of the clot C. The serrations 20 can anchor the extended end of the sub-catheter 18 to the clot C, such that when the extended sub-catheter 18 is withdrawn, the serrations 20 anchor the sub-catheter 18 to facilitate retracting the remainder of the catheter 12 deeper into the clot C. This mechanism for retracting the catheter 12 into and across the clot C bears some similarity to the biomechanical mechanism by which a parasitic wasp's ovipositor penetrates a host to deposit eggs. See Scali et al., "Ovipositor-inspired steerable needle: design and preliminary experimental evaluation," 2018 Bioinspir. Biomim. 13 016006.

[0025] Catheter 12 may include other components, such as the illustrated central lumen 21 for aspiration or for receiving a guidewire (if catheter 12 is not itself a guidewire). As another example, catheter 12 may carry a therapeutic device (not shown—e.g., an angioplasty balloon, a stent delivery device, a cutting tool, etc.).

[0026] In optical embodiments, the electronic processing device 24 includes a light source (not shown) coupled to send light to the optical fiber of the first cutting instrument 16, and an optical sensor (not shown) coupled to receive light from the optical fiber of the second cutting instrument 16 after the light exits an opening at the distal end of the first cutting instrument 14 and enters an opening at the distal end of the second cutting instrument. This light is suitably multispectral to allow measurement of a light spectrum that serves as a signature of the material disposed between the pair of cutting instruments, allowing, for example, an accurate determination of whether the tissue is clot material, vessel wall material, or blood.

[0027] In another example, the electronic processing device 24 can include a fluorescent dye (or molecular marker) delivery device configured to deliver a compound into the blood vessel V to enable imaging of the blood vessel V, the clot C, and / or portions of the catheter 12, including the sub-catheters 14, 16, 18. In some examples, the presence of collagen and elastin in the walls of the blood vessel V can induce an autofluorescence process. In another example, the cutting instruments 14, 16, 18 can include ultrasound sensors, and the tissue determination can be based on ultrasound measurements. Generally, a sensor can be included in at least two of the multiple parallel cutting instruments 14, 16, 18, configured to sense the type of tissue acted upon by at least two of the multiple parallel cutting instruments. This configuration advantageously utilizes the two cutting instruments to provide a path through the tissue, for example, as two electrodes contacting the tissue across the cutting instruments for electrical tissue measurements, or similarly to provide an optical aperture / collector for optical tissue measurements. More broadly, in some embodiments, a sensor can comprise at least one of a plurality of mutually parallel cutting instruments 14, 16, 18, the sensor configured to sense the type of tissue that the cutting instrument is acting on. For example, two electrodes for electrical tissue measurements can be integrated into one cutting element, or an optical aperture and collector can be integrated into one cutting element.

[0028] In addition to facilitating advancement of the catheter 12 through the clot C, the sub-catheters 14, 16, 18 can also function as sensor components for detecting the type of tissue the tip of the catheter 12 is interacting with. For example, the cutting instruments 14, 16, 18 may each have optical fibers extending along their length to enable optical measurements, and / or each can be made of a conductive material (e.g., metal) to enable electrical measurements. In certain examples, the measurements may include electrical impedance measurements. The cutting instruments 14, 16, 18 are connected to a motor 22 operably connected to cyclically advance each of the cutting instruments 14, 16, 18 through the catheter 12 and into the clot C in sequence. For example, the motor 22 can drive a cam mechanism to which the proximal ends of the cutting instruments 14, 16, 18 are secured. As the cam rotates, it pushes each successive cutting instrument forward and then withdraws it. The cutting instruments 14, 16, 18 are also connected via wires 26 to an electronic processing device 24 (such as a workstation computer, tablet, or more generally a computer) for implementing tissue sensors (not shown).

[0029] In electrical sensing embodiments, the electronic processing device 24 is operatively connected to measure AC electrical properties (e.g., impedance) as a function of frequency of applied current between the pair of cutting instruments 14, 16, 18, or between one of the cutting instruments and an electrical ground, a counter electrode, or another electrical reference (not shown). The resulting impedance spectrum serves as a signature of the material placed between the pair of cutting instruments, allowing for an accurate determination of, for example, whether the tissue is clot material, vessel wall material, or blood.

[0030] In some embodiments, the motor 22 is also operably connected via wires 28 to an electronic processing unit 24 configured to control the motor 22 to effect the advancement of the cutting instruments 14 , 16 , 18 .

[0031] The electronic processing unit 24 includes an electronic processor 30 (e.g., a microprocessor), optionally at least one user input device 32 (e.g., a mouse, keyboard, and / or trackball, etc.), and a display device 34 (e.g., an LCD display, a plasma display, and / or a cathode ray tube display, etc.) for displaying the results of the electrical or optical tissue measurements.

[0032] The electronic processor 30 is operatively connected to one or more non-transitory storage media 36. The non-transitory storage media 36 may include, by way of non-limiting example only, one or more of a magnetic disk or other magnetic storage medium, a solid-state drive, a flash drive or other electronic memory, an optical disk or other optical storage device, various combinations thereof, and the like. Any reference herein to a non-transitory medium or media 36 should be understood to be broadly interpreted to encompass a single medium or multiple media of the same or different types. Similarly, the electronic processor 30 may be embodied as a single electronic processor or as two or more electronic processors. The non-transitory storage media 36 store instructions executable by at least one electronic processor 30.

[0033] 1, cutting instruments 14, 16, 18 are in the form of sub-catheters 14, 16, 18 that each extend along the length of catheter 12 so that their distal ends are located at the distal end of catheter 12. This design allows motor 22, which operates cutting instruments 14, 16, 18, to be located at the proximal end of catheter 12 outside the patient.

[0034] FIG. 2 illustrates another embodiment of the vascular treatment device 10 in which the cutting instruments 14, 16, and 18 are not sub-catheters, but are instead located only at the distal end of the catheter 12. The embodiment of FIG. 2 is configured similarly to the embodiment of FIG. 1. However, here, the cutting instruments 14, 16, and 18 are located only at the distal end of the catheter 12, rather than in the form of sub-catheters extending the length of the catheter 12. To enable the cutting instruments 14, 16, and 18 to move back and forth in this embodiment, a cam mechanism or other drive mechanism 22D is located at the tip of the catheter 12 to drive the reciprocating motion of the cutting instruments 14, 16, and 18. A coupling 23 connects the distally located drive mechanism 22D to a power source located at the proximal end of the catheter 12 outside the patient. In one approach, the drive mechanism 22D includes an electric motor, in which case the coupling 23 is a pair of wires that provide power to the motor. In another approach, the motor is located at the proximal end of the catheter 12, and the coupling 23 is a mechanical coupling, such as a high torsional resistance wire, that transmits rotational force from the motor to the drive mechanism 22D. If electrical (e.g., impedance) spectroscopy measurements are to be performed, the coupling 23 may further include wires connected to the respective cutting instruments 14, 16, 18 to allow connection to an impedance meter of the electronic processing device 24. Conversely, if optical spectroscopy measurements are to be performed, the coupling 23 may further include optical fibers connected to the respective cutting instruments 14, 16, 18 to allow optical signals to be transmitted between the cutting instruments 14, 16, 18.

[0035] At least one electronic processor 30 is configured to execute occlusion passage method or process 100, as described above. Non-transitory storage medium 36 stores instructions readable and executable by at least one electronic processor 30 to perform the disclosed operations, including executing occlusion passage method or process 100. In some examples, method 100 may be performed, at least in part, by cloud processing.

[0036] 3 and with continuing reference to FIG. 1 (although method 100 is applicable to the embodiment of device 10 shown in FIG. 2), an exemplary embodiment of occlusion crossing method 100 is illustrated as a flow chart. To begin method 100, catheter 12 is inserted into blood vessel V and adjacent to clot C.

[0037] In operation 102, an electrical spectroscopy measurement is performed on at least one of the cutting devices 14, 16, 18. In some examples, the electrical spectroscopy measurement can be an impedance measurement of the cutting devices 14, 16, 18. The output is an impedance spectrum or a portion of an impedance spectrum, i.e., impedance as a function of AC frequency. In another embodiment, operation 102 can be an optical spectroscopy measurement that produces an optical spectrum. In another embodiment, impedance can be measured at specific frequencies (or only a few discrete frequencies), and tissue determination can be performed based on these measurements.

[0038] In operation 104, based on the electrical (or optical) spectroscopic measurements, the type of tissue to which the at least one cutting instrument 14, 16, 18 is applied is determined. For example, the electrical (or optical) spectroscopic measurements for the at least one cutting instrument 14, 16, 18 applied to a blood clot C differ from the electrical (or optical) spectroscopic measurements for the at least one cutting instrument 14, 16, 18 applied to healthy tissue (i.e., a blood vessel V).

[0039] In operation 106, based on the determined tissue type, a number of the plurality of cutting instruments 14, 16, 18 acting on the clot C is determined. For example, the electrical spectroscopy measurement may determine that two of the cutting instruments 14, 16, 18 are acting on the clot C, and that other of the cutting instruments 14, 16, 18 are not acting on the clot C.

[0040] In operation 108, the path of the catheter 12 relative to the clot C can be controlled based on the determined type of tissue that the cutting instruments 14, 16, 18 will act on. Using the same example, the path of the catheter 12 can be controlled by the motor 22 so that the cutting instruments 14, 16, 18 that do not act on the clot C can then act on the clot C. Advantageously, the use of at least three cutting instruments 14, 16, 18 facilitates such steering of penetration. For example, if one cutting instrument is reciprocated more frequently than the other two cutting instruments, this can tilt the direction of penetration.

[0041] The present disclosure has been described with reference to preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiments 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

1. A catheter, a plurality of parallel cutting devices disposed at least at the distal end of the catheter, each configured to act on a portion of a clot disposed within a blood vessel through which the catheter is advanced, each cutting device being independently advanceable within the clot; An intravascular treatment device comprising:

2. The endovascular treatment device of claim 1 , wherein the plurality of cutting instruments each include serrations configured to act on a portion of the clot.

3. The intravascular treatment device of claim 1 or 2, wherein each of the plurality of cutting instruments includes an optical fiber.

4. The intravascular treatment device of claim 1 , wherein each of the plurality of cutting instruments is made from an electrically conductive material.

5. and at least one electronic processor operatively connected to measure an electrical characteristic between a pair of said cutting instruments or between one of said cutting instruments and an electrical reference, said electronic processor comprising: performing an electrospectroscopy measurement on at least one of the cutting instruments; determining a type of tissue acted upon by the at least one cutting instrument based on the electrical spectroscopic measurements; The intravascular treatment device according to claim 1 , wherein the intravascular treatment device is programmed to:

6. the at least one electronic processor: determining the number of cutting instruments to act on the clot based on the determined tissue type; The intravascular treatment device of claim 5 , programmed to:

7. the at least one electronic processor: controlling a path of the catheter relative to the clot based on the determined type of tissue that the at least one cutting instrument will act on. The intravascular treatment device of claim 5 or 6, programmed to:

8. The intravascular treatment device of claim 5 , wherein the electrical spectroscopic measurements include impedance measurements.

9. a motor operably connected to cyclically advance each of said plurality of cutting instruments in sequence; The endovascular treatment device of claim 1 , further comprising:

10. 10. The endovascular treatment device of claim 1, wherein the advancing plurality of mutually parallel cutting instruments comprises at least three mutually parallel cutting instruments.

11. 10. The endovascular treatment device of claim 1, wherein the advancing multiple mutually parallel cutting instruments comprises multiple mutually parallel sub-catheters, each sub-catheter extending along the length of the catheter and having a distal end configured to act on a portion of the clot located within the blood vessel through which the catheter is advanced.

12. a sensor with at least one of the plurality of mutually parallel cutting instruments, the sensor configured to sense a type of tissue acted upon by at least one of the plurality of mutually parallel cutting instruments; The intravascular treatment device of claim 1, further comprising:

13. a flexible catheter including at least three mutually parallel flexible sub-catheters; An intravascular treatment device comprising: Each sub-catheter has a tip configured to act on a portion of the clot; each sub-catheter is independently movable relative to the other sub-catheters of the at least three parallel flexible sub-catheters; Endovascular treatment device.

14. The intravascular treatment device of claim 13 , wherein the tip of each sub-catheter has serrations on an outer surface of the tip.

15. 14. The intravascular treatment device of claim 13, wherein the at least two sub-catheters include optical fibers therethrough having optically coupled openings at the tips of the at least two sub-catheters.

16. The intravascular treatment device of claim 13 , wherein the sub-catheter comprises an electrically conductive material.

17. performing electrical spectroscopy measurements on at least one ablation tool positioned at least at the distal end of the catheter to act on a portion of a clot located in a blood vessel through which the catheter is advanced; determining a type of tissue acted upon by the at least one cutting instrument based on the electrical spectroscopic measurements; The obstruction passing method comprises:

18. determining the number of cutting instruments to act on the clot based on the determined tissue type; 20. The method of claim 17, further comprising:

19. the at least one electronic processor: controlling a path of the catheter relative to the clot based on the determined type of tissue that the at least one cutting instrument will act on.

19. The method of claim 17, wherein the method is programmed to:

20. 20. The method of any one of claims 17 to 19, wherein the electrospectroscopic measurements include impedance measurements.

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