Endovascular device comprising a plurality of electrodes

Abstract

The present invention relates to a novel endovascular device incorporating a plurality of independent electrodes on an elastic helix that allows said electrodes to be positioned against the walls of blood vessels and can assume an extended configuration enabling the removal of the device. In particular, the invention proposes incorporating the plurality of electrodes onto a core made of an elastic material such as to preserve the elasticity of the core to the greatest extent possible, specifically by securing the plurality of electrodes on the surface of the core essentially by bonding and by means of the braiding characteristics of the plurality of electrodes.

Description

[0001] Description

[0002] Title: Endovascular Device Containing Multiple Electrodes

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The present invention relates to the field of endovascular electrodes for the collection and / or stimulation of electrical signals. In particular, the invention relates to an endovascular device comprising a plurality of electrodes configured on a superelastic helix capable of returning to an extended configuration allowing the removal of said device after endovascular implantation.

[0005] TECHNICAL FIELD OF THE INVENTION

[0006] Endovascular electrodes are essential tools in the medical field, designed to collect electrical signals within blood vessels. These devices are particularly valuable for monitoring and recording cardiac or intracranial electrical activity. Furthermore, they have potential applications in monitoring neurological disorders, deep brain stimulation, and research on neurodegenerative diseases. Beyond neurological applications, these electrodes are also used to monitor cardiac activity, assess muscle function, and in the diagnosis of various vascular pathologies. The development of these electrodes focuses on achieving biocompatibility, flexibility, and precision to operate effectively in the complex and electrically noisy environment of the human body.

[0007] One of the main challenges in this field is achieving high sensitivity and accuracy in signal acquisition, while maintaining the flexibility required for insertion and positioning within blood vessels. Furthermore, devices must ensure consistent data collection despite the challenges posed by blood flow and natural body movements. Devices such as stents are designed to be securely anchored to blood vessel walls. However, stent anchoring can lead to problems such as vessel wall irritation, inflammation, or even blood clot formation. These complications underscore the importance of designing devices that minimize excessive contact with vessel walls while ensuring secure and effective fixation.

[0008] Document EP 4 282 463 A1 discloses a device used to detect or stimulate nerve tissue activity. This device comprises at least one intravascular device positioned inside a blood vessel and equipped with electrodes to detect or stimulate nerve tissue activity outside the vessel. In one embodiment, the intravascular device includes a guide wire incorporating electrodes and having a linear proximal portion and a helical distal portion with a helix diameter capable of expanding or contracting. The expanded diameter state allows the helix to be held against the vessel walls. A lower expansion force than that of a stent is provided by a spiral body with deformation capacity, achieving both a small expansion force and a position-fixing effect more readily than a rigid stent.The device is inserted via a catheter, and the cable ensures smooth gliding of the device along the catheter. The document describes the use of a guidewire with a conductive core covered by an insulator, with electrodes configured in a ring around the wire element and in electrical contact with the core. The device is designed to remain in the blood vessel for extended periods, thus facilitating long-term monitoring or stimulation. The possibility of removing the device is not addressed.

[0009] Document AU2013205434 A1 also relates to a device incorporating a flexible intravascular electrode array for cortical measurement and stimulation. The device has two positions: an insertion position, which is a cable thin enough to move through the vessels; and a deployed position, which is a helical position that extends the electrodes. When the guide wire is in the desired position, the deployed helical position is induced thermally or by removing a covering catheter. Several embodiments are described; generally, it is suggested to use a flexible, shape-memory guide wire that allows the device to be positioned in both ways and incorporates the electrodes. The electrodes are defined as uninsulated sections of the guide wire, optionally incorporating additional material by brazing, welding, chemical deposition, and other methods of attachment directly to the device.The guide wire can be made of nitinol, shape-memory alloys, and biodegradable / bioabsorbable polymers. The electrodes can be constructed with wires wrapped around the guide wire or arranged alongside it. The electrodes are made of stainless steel, gold, platinum, etc. This device is also designed to integrate the electrodes onto an elastic helix, facilitating insertion when its extended position is held by a catheter; however, the document does not mention the possibility of returning to this position or removing the device.

[0010] Ideally, a retractable endovascular device would be desirable, allowing for safe removal from the body after use and thus minimizing the risks associated with permanent implantation. Retractability would reduce potential complications such as infection, chronic inflammation, and blood clot formation. In the field of medical diagnostics, retractability would enable precise and temporary assessment of internal conditions without the need for permanent implantation. This characteristic is particularly advantageous for specific observations, such as monitoring sedated patients in intensive care, or for tracking the progression of transient pathologies at critical moments, especially during their onset.

[0011] DESCRIPTION OF THE INVENTION

[0012] The present invention aims to provide a novel retractable endovascular device incorporating a plurality of electrodes. To this end, the invention proposes an endovascular device incorporating a plurality of electrodes arranged on a helical portion of an elastic core. The core is configured to ensure increased elasticity of its helical portion, allowing it to adopt a substantially linear conformation upon implantation in a vessel and to return to this substantially linear conformation when the device is pulled for withdrawal. In other words, the elastic core is designed so that the diameter of a cylinder (in this case, a virtual cylinder) formed by and containing the helical portion is smaller than the diameter of a blood vessel at the time of insertion and / or retraction of the device into that blood vessel.

[0013] In particular, the invention relates to an endovascular device comprising a core made of elastic material having, at one end, a helical portion integrating a plurality of electrodes, and wherein each electrode of the plurality of electrodes is formed by a dedicated conductive wire comprising a conductive portion forming a tight spiral of wire wound around the core, and a connecting portion for linking said spiral with a signal processing unit at a proximal end of the core, characterized in that

[0014] - the conductive wires of the electrodes of said plurality of electrodes are braided on the surface of the core, and in that:

[0015] -said plurality of electrodes is fixed at the level of said helical part by means of braiding the conductive wires on the core, and by gluing the spirals of the electrodes with the core.

[0016] The plurality of electrodes is thus integrated on the core so as to preserve and benefit to the maximum of the elastic properties of the helical part.

[0017] Preferably, the electrode spirals are bonded to the core using adhesive zones applied to the ends of the spirals. These adhesive zones ensure the mechanical stability and electrical continuity of the electrode without the need for welding and / or crimping of the spiral ends.

[0018] In one embodiment, the electrode spirals are positioned along the core at its helical portion, and in said braiding, the connecting portions of the conducting wires are wound in the same direction around the core up to a positioning level of the spiral formed respectively by each conducting wire, such that the connecting portion of at least some of the conducting wires passes under a spiral or spirals of the electrodes positioned upstream and closer to the proximal end of the core, and such that said conducting wires are held on the core by means of said spirals. Preferably, the connecting portions of the conducting wires are braided, wound adjacently, and with a spaced turn pitch.

[0019] The device of the invention may also incorporate any of the following features or combinations of features:

[0020] - the connecting parts of the conductive wires are electrically insulated;

[0021] - the core is a nitinol wire; - the conductive wires are made of platinum, gold, silver, stainless steel, copper or CrCoMo alloy, preferably platinum.

[0022] - the electrodes are electrically isolated from the core;

[0023] - the electrodes are insulated from the core by means of an inner face of the electrodes facing the core, and said electrodes are formed by a spiral of wire having an insulating coating having been removed from an external surface of the electrode intended to be in contact with the body;

[0024] - the glue is a photopolymerizable glue;

[0025] - the plurality of electrodes is configured to provide an independent signal for each electrode;

[0026] - the helical part integrating the plurality of electrodes has an elasticity capable of switching to an extended configuration substantially linear or of reduced helix diameter when tension is applied to said helical part from the proximal end of the core, and without the need for the use of a retention element for said extended configuration;

[0027] - the core incorporates a second plurality of electrodes designed to collect extravascular signals, and located on a proximal side of the core; and

[0028] - the core includes a linear part connecting said helical part to the proximal end of the core.

[0029] Other features and advantages of the invention will become apparent from the following supplementary description, which refers to the accompanying figures. It is understood that this supplementary description is provided solely as a non-limiting illustration of the subject matter of the invention.

[0030] LIST OF FIGURES

[0031] Figure 1. A schematic representation of an endovascular device integrating a plurality of electrodes on a core comprising an elastic helical portion according to the invention.

[0032] Figure 2. A schematic representation of the braiding of the plurality of electrodes on the core of the endovascular device of the invention according to one embodiment. Figure 3. A schematic representation of a cross-section of the endovascular device at the level of one electrode of the plurality of electrodes according to an embodiment incorporating 13 electrodes.

[0033] DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention aims to provide a novel retractable endovascular device incorporating a plurality of electrodes for the stimulation and / or collection of electrical signals. To this end, the invention proposes an endovascular device integrating the plurality of electrodes arranged on an elastic helical portion of the device. In particular, the device is designed to ensure superelasticity of the helical portion, allowing it to return to a substantially linear extended conformation or a reduced diameter when subjected to tension, thus facilitating its retraction. That is to say, the endovascular device is designed so that the diameter of a cylinder (in this case, a virtual cylinder) formed by and containing this helical portion is smaller than the diameter of a blood vessel at the time of insertion and / or retraction of the device into that blood vessel.Another objective of the invention is that the plurality of electrodes is designed so that each electrode provides an independent signal.

[0035] To this end, the invention proposes an endovascular device 1 comprising a core 2 having a first linear portion, referred to as the "proximal portion," on a proximal side P of the core, and a second helical portion on a terminal side T (also called the distal side) of the core, referred to as the "helical portion," on which a plurality of electrodes 30 are integrated. The helical portion exhibits superelasticity, enabling it to adopt several configurations, including an "operational configuration" in which the helical portion retains said helical shape, allowing the electrodes to be positioned against the walls of the blood vessels 5, and an insertion or removal configuration of the device in which said helix is ​​stretched into an "extended configuration" that is substantially linear or has a reduced helix diameter.

[0036] The term "extended configuration" refers to a configuration where the diameter of the cylinder formed by the helical shape is smaller than the diameter of the blood vessel into which the device 1 is inserted, or from which it is to be removed. This cylinder diameter is subsequently referred to as the "helical diameter," "helical portion diameter," or "helix diameter." The extended configuration therefore has a smaller helical diameter than when the device 1 is in place within the blood vessel and the electrodes are in contact with the vessel wall. In the latter case, the helical diameter is equal to, or nearly equal to, the diameter of the blood vessel. This latter case corresponds to the operating configuration.

[0037] The core is made of an elastic material, preferably superelastic, and sufficiently rigid to hold the electrodes against the walls of blood vessels. Distinctively, the plurality of electrodes is braided onto the surface of the core, said core corresponding to a metallic wire shaped helically on its helical portion. In a preferred embodiment, this core is made of nitinol wire, a material known for its excellent elasticity-to-rigidity ratio and its biocompatible properties.

[0038] Optionally, the core is pre-treated with a surface treatment, such as electropolishing. For example, electropolishing the nitinol core results in a particularly smooth and homogeneous surface, reducing micro-defects that could affect mechanical performance or biocompatibility. This treatment also promotes the formation of a protective titanium oxide (TiO2) layer on the nitinol surface. This layer, generated by natural passivation after electropolishing, acts as an effective barrier to limit the release of nickel from the alloy, thus improving the device's biocompatibility.

[0039] The invention also proposes integrating the plurality of electrodes onto the core 2 in such a way as to preserve the core's superelastic properties as much as possible. In particular, the device 1 comprises a braiding of the plurality of electrodes 30 on the surface of the core 2 (i.e., the braiding corresponds to a winding of the wires, each corresponding to one of the electrodes, onto the core), and this plurality of electrodes 30 is fixed essentially by the characteristics of the braiding (i.e., by the characteristics of the winding of the wires around the core) of the plurality of electrodes and by bonding the electrodes 30 to the core 2. Figure 2 illustrates the specifics of the braiding of the plurality of electrodes 30 according to a preferred embodiment on the helical portion 20. To facilitate understanding of the braiding, the helical shape of the core is omitted here.The plurality of electrodes comprises several electrodes 30a, 30b, 30c, each electrode being formed by a tight spiral of a conducting wire 3a, 3b, 3c, wound around the core 2. By "tight spiral" is meant that the turns of the winding are contiguous for each electrode, and that the conducting wire is directly against the core 2. The conducting wires can be made of gold, silver, copper, stainless steel, an alloy such as CrCoMo, or platinum. In a preferred embodiment, the conducting wires 3a, 3b, 3c are platinum wires to maintain the elasticity of the helix, allowing good signal transmission with a small wire cross-section, and thus enabling the integration of a large number of electrodes, typically more than 10, or even more than 15 or 20.

[0040] Specifically, electrodes 30a, 30b, and 30c are attached to the core 2 by applying adhesive zones 4 to the ends of each of the spirals defining said electrodes 30a, 30b, and 30c. These adhesive zones 4 ensure the mechanical stability and electrical continuity of the electrode without the need for welding and / or crimping of the spiral ends. This attachment method is therefore highly advantageous as it preserves the core's elastic properties to the greatest extent possible. This adhesive is, for example, a biocompatible, light-curing adhesive, such as a UV-curing acrylate adhesive.

[0041] At least at the helical portion, these adhesive zones 4 will preferably be the primary means of additional fixation used to secure the electrodes 30. The plurality of electrodes is also held on the core by the characteristics of the braiding, said braiding optionally including a final coating applied outside the electrode spirals. Furthermore, the conductive wire 3 of each electrode 30a, 30b, 30c comprises a conductive portion, which forms the afferent electrode, and a connecting portion. The connecting portion extends wound along the core 2 from the conductive portion (i.e., the electrode) to the proximal portion, or even to the proximal end of the proximal portion. The conductive portion is preferably not electrically insulated at the surface intended to be in contact with the wall of the blood vessel when the device 1 is in said blood vessel.This means that the portion of each electrode that is in contact with the blood vessel wall is not electrically insulated. This uninsulated portion is called the "active surface" of the electrode. Preferably, the connecting part is also electrically insulated.

[0042] The connecting portion can be such that it passes, where appropriate, beneath a spiral of one or more electrodes positioned upstream in the braiding of the plurality of electrodes, i.e., closer to the proximal end of the core 2. This braiding allows the spirals of the electrodes 30 to be used to secure the connecting portions of the conductive wires 3 forming each electrode. As illustrated in Figure 2, each electrode 30a, 30b, 30c is formed by an independent wire providing an independent signal to a signal processing and acquisition unit. Similarly, the spiral design of the electrodes using a dedicated conductive wire allows for better conformity to the helical design and also avoids soldering with connecting wires for signal transmission, thus preserving the elasticity of the core.

[0043] In other words, the connecting portion of a conducting wire 3 can be positioned along the core, typically by winding it around the core, so that this connecting portion is held on the core by the conducting portion forming another electrode of the plurality of electrodes. That is to say, the connecting portion of at least some of the conducting wires forming the plurality of electrodes runs along the core so as to pass under the electrodes located upstream on the helical portion. An "upstream electrode" is understood to be an electrode located between the proximal portion and the electrode associated with the conducting wire in question (passing under the upstream electrode). This upstream electrode is therefore located upstream relative to the electrode associated with the wire in question.

[0044] In particular, each electrode in the plurality of electrodes is positioned at a given distance from the proximal portion, typically the proximal end of the proximal portion. The plurality of electrodes thus includes a first electrode positioned on the helical portion such that its distance from the proximal portion is the smallest, compared to the distance of the other electrodes in the plurality of electrodes from the proximal portion (typically the proximal end of the proximal portion). Each electrode, other than the first electrode, has its afferent conducting wire positioned on the core so that it runs under the electrodes in the plurality of electrodes for which the distance from the proximal portion is smaller than that of the electrode in question (thus also including the first electrode).

[0045] For illustration, in relation to Figure 2, the conducting wire for electrode 30a passes under electrode 30b and under electrode 30c, which are located upstream of electrode 30a. The conducting wire for electrode 30b passes under electrode 30c, upstream of electrode 30b. Electrode 30c therefore corresponds here to the first electrode mentioned above.

[0046] Thus, at the level of a given electrode, the conducting wires relating to the electrodes located downstream (i.e., relating to each of the electrodes whose distance to the proximal part is greater than the distance of the given electrode to the proximal part) are positioned under the given electrode.

[0047] The connecting sections of the various conducting wires are, for example, wound around the core, adjacent to each other in the same direction, thus avoiding wire crossings to maintain the flexibility and mechanical integrity of the device. Figure 2 illustrates a non-limiting embodiment with three electrodes 30a, 30b, 30c. On a proximal side P of the helical portion, the wires 3c, 3b, 3a are seen wound adjacently around the core 2, particularly their connecting sections, with a spaced turn pitch p. Each conducting wire is wound at the turn pitch p to its conductive section. Each electrode (i.e., each conductive section) is formed by a tight winding of the corresponding conducting wire. Wires 3b and 3a are secured to the core by the spiral corresponding to electrode 30c, and pass through the underside of the spiral of electrode 30c to continue the braiding according to the same principle towards the terminal side T of the helical part 20.The spaced turn pitch in the winding of the connecting sections reduces the overall length of the conductive wires, thus limiting impedance and ensuring good reception of electrical signals. Furthermore, the close proximity of the connecting sections (i.e., adjacent) allows for better support of the spiral ends, thereby ensuring electrical continuity of the spirals, i.e., the electrode pads. In the present invention, spaced turn pitch means that a minimum distance, here the pitch p, is maintained between each turn of one or more conductive wires wound along the core 2. The conductive wires 3 are electrically insulated from the core to prevent short circuits with the conductive metallic material of the core 2. To this end, the conductive wires have a biocompatible insulating coating that completely covers the wire connection sections and the inner face of the spirals in contact with the core.In one embodiment, the braiding of the plurality of electrodes is done with conductive wires having an insulating coating, and this coating is then removed from the outer surface of the spirals. The outer face of the spirals corresponds to the active surface of the electrodes, i.e., their surface intended to be in contact with the body (typically the wall of a blood vessel, such as an artery) and to collect the signal, and their inner face corresponds to their surface in contact with the core.

[0048] Figure 3 shows a schematic representation of a cross-section at the proximal electrode spiral of the helix, beneath which pass the connecting sections of the conductive wires of the downstream electrodes. The outer surface of the core 2 is covered by the connecting sections of the conductive wires of the more distal electrodes of the device. Also shown are the insulating coating areas i on the conductive wires 3 at the connection sections and on the inner face of the electrode spiral 30. The insulating coating is, for example, a polyamide coating. The total cross-section of a cable thus formed is approximately 70–650 µm, in which the cross-section of the nitinol wire is approximately 50–450 µm, and the cross-section of the conductive wires is approximately 10–100 µm.

[0049] The number of electrodes in the plurality of electrodes can be easily increased by increasing the length of the helix, and, when desired, a spaced turn pitch (p) for winding the connecting parts around the core 2. The number of turns of the electrodes determines the active surface area, and in a non-limiting embodiment, the size of the electrode (specifically, their length along a direction orthogonal to the winding direction of the afferent conductive wire, i.e., their length along the elongation direction of the core) will be approximately 1–2 mm. The diameter of the helical portion will be chosen according to the blood vessel into which the device is intended to be implanted and will be a maximum of approximately 10 mm, the maximum size of a vessel. The turn pitch of the helical portion, as well as the spacing between the electrodes, will be chosen according to the intended use of the device.Similarly, in one embodiment, the device incorporates equivalently braided electrodes on the proximal P side of the core, such as on the linear proximal end of the core intended to collect the signal outside the patient. In one embodiment, the device is manufactured by first applying the helical shape to the terminal end of the core, preferably after surface pretreatment. In a second step, the plurality of electrodes is braided onto the surface of the core. Finally, a final coating is preferably applied to the braiding of the plurality of electrodes, particularly outside the areas of the electrode spirals, to improve lubrication and smoothness of the device during intravascular insertion or removal, and / or to enhance biocompatibility. Naturally, this coating also improves the retention of the plurality of electrodes on the core.For example, this final coating is a thin hydrophilic coating such as a polytetrafluoroethylene (PTFE) or hydrophilic hydrogel coating. In one embodiment, the endovascular device of the invention is a neurovascular microguide for recording cerebral electrical activity, and finds application in a method of collecting intracranial signals to perform a pre-surgical assessment of drug-resistant epilepsies.

Claims

DEMANDS 1. Endovascular device (1) comprising a core (2) made of elastic material having, at one end, a helical portion integrating a plurality of electrodes (30), and wherein each electrode (30a, 30b, 30c) of the plurality of electrodes (30) is formed by a dedicated conducting wire (3a, 3b, 3c) having a conducting portion forming a tight spiral of wire wound around the core (2), and a connecting portion for linking said spiral with a signal processing unit at a proximal end of the core, characterized in that - the conducting wires (3a, 3b, 3c) of the electrodes (30a, 30b, 30c) of the plurality of electrodes (30) are braided on the surface of the core (2), and in that: -the plurality of electrodes (30) is fixed at the level of said helical part by means of braiding the conducting wires on the core (2), and by gluing the spirals of the electrodes with the core (2).

2. Device according to claim 1, wherein the spirals of the electrodes (30a, 30b, 30c) are glued to the core (2) by means of the glue zones (4) applied at the ends of said spirals.

3. A device according to any one of the preceding claims, wherein the spirals of the electrodes (30a, 30b, 30c) are positioned along the core (2) at the level of its helical part, and in said braiding, the connecting parts of the conducting wires are wound in the same direction around the core (2) up to a positioning level of the spiral formed respectively by each conducting wire (3a, 3b, 3c), and such that the connecting part of at least a part of the conducting wires passes under a spiral or spirals of the electrodes positioned upstream (30b, 30c) and closer to the proximal end of the core (2), and such that said conducting wires are held on the core (2) by means of said spirals.

4. Device according to claim 3, in which the connecting parts of the conducting wires are braided wound adjacently and with a spaced turn pitch (p).

5. Device according to any one of the preceding claims, wherein the connecting parts of the conducting wires are electrically insulated.

6. Device according to any one of the preceding claims, wherein the core is a nitinol wire.

7. Device according to any one of the preceding claims, wherein the conducting wires (3a, 3b, 3c) are made of platinum, gold, silver, stainless steel, copper or CrCoMo alloy, preferably platinum.

8. Device according to any one of the preceding claims, wherein the electrodes (30a, 30b, 30c) are electrically isolated from the core (2).

9. Device according to any one of the preceding claims, wherein the electrodes are insulated from the core (2) by means of an inner face of the electrodes facing the core (2), and said electrodes (30a, 30b, 30c) are formed by a spiral of wire having an insulating coating having been removed on an external surface of the electrodes intended to be in contact with the body.

10. Device according to any one of the preceding claims, wherein the glue is a photopolymerizable glue.

11. Device according to any one of the preceding claims, wherein the plurality of electrodes is configured to provide an independent signal for each electrode.

12. Device according to any one of the preceding claims, wherein the helical part incorporating the plurality of electrodes (30) has an elasticity capable of switching to a substantially linear extended configuration or reduced helix diameter when said helical part is tensioned from the proximal end of the core (2), and without the need for the use of a retention element for said extended configuration.

13. Device according to any one of the preceding claims, wherein the core incorporates a second plurality of electrodes for collecting extravascular signals, and being located on a proximal side of the core (2).

14. Device according to any one of the preceding claims, wherein the core (2) comprises a linear part connecting said helical part to the proximal end of the core.

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