Endovascular device with guide wire

Abstract

The invention relates to an endovascular device (1) with a stent structure (2) which is provided in an expanded state, in which it is at least temporarily released in a blood vessel, and in a compressed state, in which it is introduced into the blood vessel in a microcatheter, wherein the stent structure (2) has a substantially cylindrical main portion (3), wherein the stent structure (2) has at least one point of connection (6) with a guide wire (5) and the guide wire (5) extends distally beyond the stent structure (2), wherein the guide wire (5) runs along the periphery of the stent structure (2). According to an alternative embodiment, the stent structure (2) is connected to a tube (12) through which a guide wire (5) extends distally beyond the stent structure (2). The device (1) according to the invention permits the simultaneous introduction of guide wire (5) and stent structure (2) into the blood vessel together with a microcatheter without there having to be, in the interim, a change between guide wire (5), microcatheter and stent structure (2).

Description

[0001] Endovascular device with guidewire

[0002] The invention relates to an endovascular device comprising a stent structure which is in an expanded state in which it is at least temporarily released into a blood vessel and in a compressed state in which it is introduced into the blood vessel through a microcatheter, wherein the stent structure has a substantially cylindrical main portion.

[0003] Thromboembolic diseases such as myocardial infarction, pulmonary embolism, peripheral thrombosis, organ embolism, etc., are typically triggered by a thromboembolus (hereinafter referred to as a thrombus), i.e., a viscoelastic blood clot composed of platelets, fibrinogen, clotting factors, etc., that has lodged in a blood vessel and completely or partially occludes it. The occlusion of organ arteries leads to an interruption of the supply of oxygen and nutrients to the dependent tissue. The disruption of functional metabolism with loss of function is quickly followed by the cessation of structural metabolism with the destruction of the affected tissue (infarction). The organs most commonly affected by this in humans are the heart and brain. However, such changes also affect the arteries of the extremities and the pulmonary arteries. Venous thrombosis and thromboembolic occlusions also occur frequently in the leg and pelvic veins.The clinical picture of a thrombotic occlusion of an intracranial sinus can lead to severe cerebral hemorrhages due to the disruption of venous drainage of the brain tissue.

[0004] Given the severity of the conditions caused by thromboembolism and the frequency of these diseases, various techniques for dissolving or removing thrombi are known. For example, patients can be treated with thrombolytic agents such as streptokinase or urokinase, or with anticoagulants, which serve to thrombolyse the thrombus or contain its growth. Since these treatment methods are usually time-consuming, they are often combined with methods for fragmenting or removing the thrombus or embolus.

[0005] In addition to open surgical procedures, transluminal or endovascular catheter-guided interventional therapies are increasingly being used in the state of the art because they are less invasive. For example, it is known to remove the thrombus from the patient's body using suction catheters that generate negative pressure or mechanically with catheters equipped with baskets, coils, hooks, or the like; see US 6,245,089 B1; US ​​5,171,233 A1, Thomas E. Meier et al., Stroke 2002 (9), 2232.

[0006] The disadvantage of thrombolytic treatment methods is that they are rarely successful after the time window has expired. Even the well-known transluminal devices often cannot completely remove a thrombus, and there is also a risk that the thrombus or fragments may become released and travel through the bloodstream to smaller-bore vessels, where they are more difficult to reach and treat.

[0007] WO 2012 / 156069 A1 discloses a thrombectomy device with a slit that extends helically across the outer surface of the device, with a tensioning bar spanning the slit at the proximal end in a wave-like manner. After capturing the thrombus, the device is retracted into a microcatheter (aspiration catheter) and removed from the vascular system together with the thrombus. This thrombectomy device is particularly suitable for removing thrombi from small-lumen or highly tortuous vessels, such as those of the brain.

[0008] Other endovascular devices are implants that, unlike thrombectomy devices, are not designed to be removed from the blood vessel system after capturing a thrombus, but are intended to remain permanently in the blood vessel. Such implants include stents, for example, which serve to keep a blood vessel open, particularly after a stenosis (narrowing) in the blood vessel has been eliminated. The latter can be achieved using angioplasty (PTA) and a balloon catheter. Typically, stents have a tubular structure and are either laser-cut, creating a surface of struts with openings between them, or consist of a wire mesh. Stents can be delivered to the target site via a catheter and expanded there; in the case of self-expanding stents made of shape-memory materials, this expansion and attachment to the inner vessel wall occurs automatically.

[0009] Another type of implant that is permanently inserted into the blood vessel is a flow diverter. These are placed in front of the neck of an aneurysm to prevent or at least significantly reduce the flow of blood into the aneurysm, ultimately resulting in obliteration of the aneurysm. Flow diverters generally have a higher surface density than conventional stents used to keep a blood vessel open. An example of a flow diverter is described in the application WO 2008 / 107172 A1.

[0010] Stents or flow diverters can also be used to prevent occlusion agents or embolic agents introduced into an aneurysm from escaping the aneurysm. Coils, i.e. small wire coils, are often used as occlusion agents. If these escape from an aneurysm into the bloodstream, it can lead to significant complications and occlusions or injury to more distal blood vessels. This is prevented by stents or flow diverters placed in front of the aneurysm. If a sufficient number of occlusion agents have been introduced into the aneurysm, they interlock and thus prevent each other from escaping the aneurysm. This means that once the aneurysm is completely filled, further covering of the aneurysm neck may not be necessary.The technique of placing an additional endovascular device in front of the aneurysm to prevent the leakage of occlusion agents is also called “jailing.”

[0011] Another area of ​​application for endovascular devices is the treatment of vasospasm. Vasospasm is defined as a spasmodic narrowing of a blood vessel. This carries the risk that subsequent vessels will no longer receive sufficient blood supply (ischemia), which can lead to necrosis of the tissue supplied with blood by the vessels. Particularly in the cerebral region, vasospasm can occur several days after a subarachnoid hemorrhage (SAH), often as a result of the rupture of an aneurysm. WO 2017 / 207689 A1 describes a device for treating vasospasm. This essentially consists of a stent structure that does not remain permanently in the blood vessel system, but is placed at the site of the vasospasm, expanded there, and then withdrawn again. Implants that remain permanently in the blood vessel for the treatment of vasospasm are also conceivable.

[0012] The typical procedure for inserting an endovascular device is to first place a guidewire, over which a microcatheter is advanced to the target position. The guidewire is then removed, and finally, the endovascular device itself is introduced through the microcatheter. Typically, a guide catheter is also used, through which the microcatheter is initially advanced. The distal end of the guide catheter is positioned proximal to the actual target position, meaning that the microcatheter is advanced beyond the distal end of the guide catheter.

[0013] In principle, this procedure has proven effective, but it requires several steps and therefore a certain amount of time. Especially for time-critical treatments such as thrombus removal, it would be desirable to have an endovascular device that allows for faster positioning of the device at the target site. Furthermore, simplified handling would be desirable.

[0014] The object of providing a corresponding device is achieved according to the invention by an endovascular device with a stent structure which is present in an expanded state in which it is at least temporarily released into a blood vessel, and in a compressed state in which it is introduced into the blood vessel in a microcatheter, wherein the stent structure has a substantially cylindrical main section, wherein the stent structure has at least one connection point with a guide wire and the guide wire extends distally beyond the stent structure, wherein the guide wire runs along the periphery of the stent structure. The invention is based on the idea of ​​bringing the stent structure and the guide wire to the target position in one process together with the microcatheter.The guidewire is connected to the stent structure, with the guidewire extending further distally beyond the distal end of the stent structure.

[0015] During insertion, the stent structure with mounted guidewire is typically inserted in a compressed state into a microcatheter. It is positioned in the microcatheter such that the distal end of the guidewire protrudes distally from the microcatheter. Typically, the endovascular device is pushed the appropriate distance into the microcatheter for this purpose. The microcatheter, together with the endovascular device contained in the microcatheter, can then be advanced distally in a guide catheter and finally in the blood vessel itself until the stent structure has reached the target position. Release is then usually achieved by retracting the microcatheter in a proximal direction while maintaining the position of the endovascular device, or possibly by further advancing the endovascular device in a distal direction while maintaining the same position of the microcatheter.The withdrawal of the microcatheter and the advancement of the endovascular device can also be combined. Because the guidewire protrudes distally from the microcatheter, the guidewire remains capable of guiding the microcatheter and its stent structure through the vascular system. The advantage of this approach is that the conventional transition between guidewire, microcatheter, and finally endovascular device is eliminated, making the procedure simpler and more time-saving.

[0016] The guidewire runs along the periphery of the stent structure so that when the stent structure expands, its function is not impaired by the guidewire itself. If, for example, the endovascular device is used to remove thrombi, the stent structure can penetrate the thrombus without the still-present guidewire interfering. The device can also be withdrawn with the captured thrombus, for example into an aspiration catheter, while the stent structure remains connected to the guidewire. This also distinguishes the device according to the invention from devices known from the prior art, in which a device is sometimes fixed to an introduction wire, but the release of the device occurs precisely by severing the connection between the device and the introduction wire, which is not the case with the invention.

[0017] The connection between guide wire and stent structure can be fixed, i.e. the guide wire remains fixed relative to the stent structure both with regard to rotation and with regard to longitudinal displacement. This type of design has the advantage of being particularly simple. The fixed connection between stent structure and guide wire can be created, for example, by gluing, welding or soldering. Since in this case twisting of the guide wire relative to the stent structure is also not possible, it is advantageous for probing, i.e. the careful advancement of the device in a distal direction through the blood vessel system, whereby the treating physician has to follow bends in the respective blood vessel, if the distal section of the guide wire is curved to the side or, better still, in a proximal direction. In other words, the distal end of the guide wire can have a J-shape or walking stick shape.The guide wire thus follows bends in the blood vessel largely automatically, without the risk of damaging the vessel wall.

[0018] However, connections between the stent structure and the guidewire that allow degrees of freedom of movement between the guidewire and the stent structure are particularly advantageous. For example, the connection point can be a fixed bearing that allows rotation of the guidewire relative to the stent structure while preventing longitudinal displacement. As the endovascular device and microcatheter are advanced, the attending physician can rotate the guidewire accordingly to probe the further course of a blood vessel. In this embodiment, too, a distal section of the guidewire with a curvature to the side or in a proximal direction is advantageous to further simplify probing and prevent injury to the inner vessel wall.

[0019] Finally, according to a further advantageous embodiment, the connection point between the stent structure and the guidewire is a floating bearing, which allows the guidewire to be moved longitudinally and rotated relative to the stent structure. This allows the attending physician to not only rotate the guidewire during advancement to better follow the course of the blood vessel, but also to carefully slide it back and forth relative to the stent structure and microcatheter. Typically, the longitudinal movement of the guidewire is limited proximally and distally by stops.

[0020] According to a particularly advantageous embodiment, the stent structure has at least two connection points to the guidewire, one connection point being a fixed bearing that allows rotation of the guidewire relative to the stent structure, and one connection point being a loose bearing that allows longitudinal displacement of the guidewire and rotation of the guidewire relative to the stent structure, the fixed bearing and the loose bearing being spaced apart from one another in the longitudinal direction. The combination of fixed bearing and loose bearing serves to compensate for the change in length of the stent structure that occurs when the stent structure is compressed or expanded. This is the case when the stent structure is inserted into the microcatheter, and also during release.During expansion during release of the stent structure, it shortens, whereas during compression during insertion into a catheter, it stretches. To prevent curvature or bending of the guidewire in this context, two connection points between the guidewire and the stent structure are advantageous. One of which remains fixed with regard to longitudinal displacement, while the other allows relative longitudinal displacement between the guidewire and the stent structure. Typically, the more distal connection point is designed as a loose bearing, while the more proximal connection point is designed as a fixed bearing; however, the reverse configuration is also possible. With regard to the loose bearing, it is also advisable to limit the longitudinal displacement, particularly by means of stops.

[0021] According to an alternative embodiment, an endovascular device is provided with a stent structure which is present in an expanded state in which it is at least temporarily released into a blood vessel, and in a compressed state in which it is introduced into the blood vessel in a microcatheter. The stent structure has a substantially cylindrical main section and at least one connection point with a tube through which a guidewire extends, which can be brought into a position in which it extends distally beyond the stent structure. According to this alternative embodiment, the stent structure is thus not connected directly to the guidewire, but to a tube through whose lumen the guidewire extends.Even with this design, the guidewire extends distally beyond the stent structure during use, allowing for probing of the blood vessel and advancing the guidewire together with a microcatheter containing the endovascular device. The guidewire can be moved and rotated longitudinally through the tube, further simplifying advancement through the vascular system and probing.

[0022] The tube to which the stent structure is connected can also be referred to as a hypotube. This is usually understood to be a thin tube with an internal cavity or lumen, such as that used as the proximal section of a catheter. The tube is usually metallic and can be made of stainless steel or a cobalt-chromium alloy, for example.

[0023] To increase the flexibility of the tube, it can have slots or notches. These are typically inserted into the tube from the outside and run essentially orthogonally to the longitudinal direction. Diagonal or spiral slots or notches are also possible.

[0024] As in the first embodiment, in which the stent structure is directly connected to the guide wire, the guide wire preferably runs along the periphery of the stent structure when the stent structure is connected to the tube, so that when the stent structure expands, its function is not impaired by the guide wire itself.

[0025] The guidewire, in turn, ideally has a distal section that is curved laterally or proximally. This makes it easier for the attending physician to find and probe the path through the blood vessel without risking damage to the blood vessel.

[0026] Regardless of the embodiment of the invention and the design of the connection points, when reference is made to a stent structure according to the invention, this is understood to be a substantially tubular structure, similar to that used in stents. This applies regardless of whether the endovascular device is actually used as a stent in the true sense of the word or as a thrombectomy device, flow diverter, device for treating vasospasm, or for other purposes. The stent structure has a substantially cylindrical main section that makes up the largest part of the length of the stent structure. The stent structure can be open or closed at the proximal and distal ends. Open means that there are no struts or wires at either end of the stent structure, and that struts / wires are limited to the outer circumference (surface area) of the stent structure.With a closed end, however, struts or wires are also present in the center of the stent structure. Because there are openings between the struts or wires, even with a closed distal end, this end is not completely sealed; blood flow can still occur through the openings. At the distal end of the stent structure, it can be essentially cylindrical, as in the main section, but a different design is also possible, for example, a radially expanded distal end, which can also be referred to as a trumpet shape.

[0027] The terms "proximal" and "distal" are to be understood in such a way that, during insertion of the device, parts facing toward the attending physician are referred to as proximal, and parts facing away from the attending physician are referred to as distal. The device is therefore typically advanced distally through the vascular system together with the microcatheter. The term "axial" refers to the longitudinal axis of the device, running from proximal to distal, while the term "radial" refers to planes perpendicular to this axis.

[0028] The stent structure, which is cylindrical at least in some areas and preferably entirely, generally has openings or cells distributed across the cylinder's outer surface. In other words, it is a lattice or mesh structure constructed from struts, webs, or wires, resulting in a multitude of openings / cells on the cylinder's outer surface.

[0029] A stent structure composed of interconnected webs or struts can be manufactured by laser cutting in a generally known manner; in this context, they are also referred to as cut structures. This creates a multitude of openings or a mesh structure within the stent structure, with the openings distributed over the circumference of the stent structure. Other manufacturing processes are also conceivable, for example, electroplating or lithography, 3D printing, or rapid prototyping.

[0030] Alternatively, the stent structure can also be a mesh structure made of wires forming a braid. The wires typically run helically along the longitudinal axis, with opposing wires running over and under each other at the intersection points, forming honeycomb-shaped openings between the wires. The total number of wires is preferably 8 to 128. The wires forming the mesh structure can be individual metal wires, but it is also possible to provide strands, i.e., several small-diameter wires that together form a filament and are preferably twisted together.

[0031] The term "opening" or "cell" refers to the lattice structure, regardless of whether the opening is separated from the environment by a membrane. In other words, an opening covered by a membrane is also referred to as an opening. A membrane can be applied externally or internally to the lattice structure, if required. Embedding the lattice structure in a membrane is also possible. The membranes can be made of a polymer material such as polytetrafluoroethylene, polyester, polyamides, polyurethanes, polyolefins, or polysulfones. Polycarbonate urethanes (PCU) are particularly preferred.

[0032] One advantage of a stent structure made of interconnected webs or struts, particularly one produced by laser cutting, over a mesh structure made of wires is that a stent structure made of struts is less prone to longitudinal contraction upon expansion than a mesh structure. When used as a thrombectomy device (a device for removing thrombi and clots from blood vessels), a stent structure made of interconnected struts is also advantageous in that the radial force exerted by such a stent structure, with otherwise comparable construction, strut-to-wire density, and strut-to-wire thickness, is higher than that exerted by a mesh structure made of wires. This is because the struts are firmly connected at their intersection points, whereas the wires in a mesh structure typically only run over and under each other.

[0033] The struts or wires can have a round, oval, square, rectangular, or trapezoidal cross-section. Rounded edges are advantageous in the case of a square, rectangular, or trapezoidal cross-section. Additionally, electropolishing the stent structure is recommended to make it smoother and more rounded, thus reducing the trauma. Furthermore, the risk of germs or other contaminants adhering to the surface is reduced. The use of flat struts / wires in the form of thin strips, particularly metal strips, is also possible.

[0034] The diameter of the stent structure in the freely expanded state is typically in the range of 2 to 8 mm, preferably in the range of 4 to 6 mm. The total length of the stent structure in the expanded state is generally 5 to 50 mm, preferably 10 to 45 mm, more preferably 20 to 40 mm.

[0035] In the case of a stent structure made of struts, for example, it can be cut from a tube with a wall thickness of 25 to 70 μm; in the case of a mesh structure made of interwoven wires, the wire thickness is preferably 20 to 70 μm. A microcatheter, with which the device can be delivered to the target site in a compressed state, has an inner diameter of 0.4 to 0.9 mm, for example.

[0036] Advantageously, the stent structure has a tapered proximal section proximal to the cylindrical main section, which tapers towards a connection point with the guidewire or tube located on the periphery of the stent structure. Accordingly, the guidewire can run straight in the longitudinal direction of the device, namely along the periphery of the stent structure. In this context, the periphery of the stent structure refers to the peripheral surface of the stent structure, which can also be referred to as the lateral surface. The eccentric attachment of the guidewire is also advantageous in that it prevents the guidewire from impairing the functions of the endovascular device and the stent structure or from obstructing blood flow.The eccentric arrangement of the guidewire also facilitates retraction of the device into the microcatheter, if necessary, or into an aspiration catheter.

[0037] It is advantageous if the distal section of the guidewire has as uniform a curvature as possible to the side or in the proximal direction. This makes it easier to follow even narrow, sharply curved blood vessels with the guidewire. The distal end of the guidewire therefore does not simply protrude in a pointed manner in the distal direction, but has a rounded end, for example a J-shape. The curvature of the distal section of the guidewire is particularly important when there is little or no freedom of movement between the guidewire and the stent structure, i.e. particularly when there is a fixed connection between the guidewire and the stent structure.

[0038] Furthermore, it is advantageous if the guidewire, particularly in its distal section, exhibits a certain degree of flexibility. This can be ensured by appropriate material selection. For example, a shape memory metal with superelastic properties, such as a nickel-titanium alloy, can be used as the material for the guidewire. One such alloy is known as Nitinol. Other preferred materials for the guidewire are stainless steel or cobalt-chromium alloys. In particular, a distal section of the guidewire can be made of a particularly flexible material, such as a shape memory metal, while more proximal areas can be made of a different material, such as stainless steel.

[0039] Furthermore, it is advantageous to make at least parts of the distal section of the guidewire radiopaque. This helps the attending physician monitor the advancement of the guidewire, and thus also the stent structure and microcatheter, in the X-ray image. For example, parts of the guidewire can be marked with platinum or platinum-indium, or even with a gold coating.

[0040] The stent structure is advantageously self-expanding, so that it automatically assumes the expanded state after being released from the microcatheter. To ensure this, the stent structure can be constructed from a material with shape memory properties, or at least contain such properties. Nickel-titanium alloys such as Nitinol are also suitable for this purpose. However, polymers with shape memory properties or other alloys, such as nickel-titanium-chromium or nickel-titanium-copper alloys, are also conceivable. The use of cobalt-chromium or cobalt-chromium-nickel alloys is also possible.

[0041] The cylindrical main section is typically formed from a multitude of cells distributed around its circumference, which are open in the radial direction. In other words, the cylindrical main section, and often the entire stent structure, has a lattice or mesh structure constructed from struts or wires, with cells located between the struts or wires.

[0042] The resulting cells in the stent structure can be completely closed, i.e., surrounded by struts or wires without interruptions (so-called "closed-cell design"). An "open-cell design" is also possible, in which at least some struts / wires have an interruption, so that the cells formed by the struts / wires are at least partially open, i.e., not completely closed. Such an open-cell design exhibits greater flexibility, which can be advantageous in highly tortuous blood vessels. On the other hand, the retractability of the device is limited in an open-cell design.

[0043] It is also possible to provide the stent structure or the cylindrical main section with a slot that extends helically over the outer surface of at least parts of the stent structure or in the longitudinal direction, i.e., essentially parallel to the longitudinal axis, along the outer surface of at least parts of the stent structure. Individual struts or wires can span the slot to influence the radial force distribution. A corresponding thrombectomy device with a continuous slot parallel to the longitudinal axis is disclosed in WO 2009 / 105710 A1, and a device with a helical slot and a clamping bracket at the proximal end of the stent structure is disclosed in WO 2012 / 156069 A1.

[0044] To facilitate visualization of the insertion procedure for the attending physician, it is advisable to provide at least some areas of the endovascular device with radiopaque markers. The radiopaque markers can be made of platinum, palladium, platinum-iridium, tantalum, gold, tungsten, or other radiopaque metals. For example, radiopaque / radiopaque coils can be attached to various points on the device. It is also possible to coat the stent structure, particularly the struts or wires of the stent structure, with a coating of a radiopaque material, such as gold. This coating can have a thickness of 1 to 6 μm, for example. The coating with a radiopaque material does not have to cover the entire stent structure; it is particularly important in the areas of the stent structure that expand towards the inner vessel wall, i.e.essentially in the main cylindrical section of the stent structure to allow for observation of the stent structure's expansion. However, even when providing a radiopaque coating, it may be useful to additionally apply one or more radiopaque markers to the device, particularly at the distal end of the stent structure.

[0045] An additional option is the use of struts or wires made of a metal with shape memory properties, in particular a corresponding nickel-titanium alloy, which at least partially contain a platinum core. Such struts / wires are known as DFT wires (DFT = drawn-filled tubing). In this way, the advantageous properties of nickel-titanium, namely its shape memory properties, are combined with the advantageous properties of platinum, namely its X-ray visibility.

[0046] Loose struts or wire ends may be present at the proximal and distal ends of the stent structure, although these should preferably be designed to be atraumatic to avoid injury to the blood vessel. The atraumatic design of the ends can be achieved, for example, by rounding them. Another option is to loop the struts or wires at one or both ends of the stent structure and then loop them back into the stent structure. Accordingly, the end of the stent structure no longer has any free strut or wire ends, thus reducing the risk of injury to the blood vessel wall.

[0047] In particular, the endovascular device according to the invention can be a device for removing thrombus from blood vessels. Such a device is brought within the microcatheter to the location of the thrombus to be removed and released from the microcatheter there, whereupon the stent structure of the device expands into the thrombus and absorbs the thrombus. The endovascular device is then retracted with the captured thrombus, typically into an aspiration catheter that has a larger inner diameter than the microcatheter to prevent the thrombus or parts of it from being "squeezed out" of the stent structure during compression. At the same time, any detached thrombus fragments can be suctioned away.

[0048] The invention is particularly suitable for a thrombectomy device because the removal of a thrombus that could potentially cause an ischemic stroke is time-critical. By eliminating multiple sequential steps involving switching between the guidewire, microcatheter, and thrombectomy device, valuable time can be saved by the invention. The microcatheter and thrombectomy device are introduced into the blood vessel simultaneously with the guidewire. Recanalization is therefore faster. Since the guidewire runs along the periphery of the stent structure, it has virtually no impact on the effectiveness of the thrombectomy device on site. After capturing the thrombus, the entire thrombectomy device, including the guidewire, is removed from the blood vessel system; therefore, separation of the guidewire from the thrombectomy device is generally not necessary.

[0049] Nevertheless, the endovascular device according to the invention can also be an implant, in particular a stent for keeping blood vessels open, a flow diverter for inhibiting the inflow of blood into an aneurysm, or a stent intended to prevent occlusion agents from escaping the aneurysm. Another possible use is as a device for treating vasospasm, whereby the treatment can be based in particular on a temporary or permanent expansion of the stent structure (cf., e.g., WO 2017 / 207689 A1) or on the application of electrical, radiofrequency, or ultrasound pulses (cf. WO 2018 / 046592 A1).

[0050] Particularly in the case of an implant, it must be possible to separate the stent structure so that it can remain in the blood vessel. It is preferred to provide a detachable stent structure from the guidewire or tube so that the guidewire / tube can be withdrawn from the blood vessel system while the stent structure remains in the target position. In this way, any effects of the guidewire that could influence the function of the stent structure are excluded. Accordingly, the connection points between the guidewire / tube and the stent structure should be designed to be detachable. Various detachment mechanisms are known from the prior art, in particular electrolytic, mechanical, thermal, and chemical separation options.Detachability may also be useful for endovascular devices that are intended to be removed from the blood vessel system, particularly thrombectomy devices and devices used to treat vasospasm, in the event that withdrawal of the device proves to be problematic during treatment and the physician decides to leave the device in the blood vessel.

[0051] The detachment point(s) used to separate the stent structure are preferably electrolytically corrodible. In this case, the at least partial dissolution of the detachment point occurs by applying an electrical voltage to the detachment point using a voltage source. During electrolytic detachment, the detachment point is electrolytically corroded by applying a voltage, causing the stent structure to detach from the guidewire. This is usually direct current, with a low current (< 3 mA) sufficient. The detachment point is usually made of metal and, when the electrical voltage is applied, forms the anode at which oxidation and thus dissolution of the metal takes place.

[0052] To prevent anodic oxidation of the stent structure, it can be electrically insulated from the detachment point and the guidewire. The electrolytic detachment of implants is well known in the art, for example for occlusion coils for closing aneurysms, see, for example, WO 2011 / 147567 A1. The principle is based on the fact that when a voltage is applied, a detachment point made of a suitable material, in particular metal, usually undergoes anodic oxidation to such an extent that the regions of the device distal to the corresponding detachment point are released. The detachment point can be made, for example, of stainless steel, magnesium, magnesium alloys, or a cobalt-chromium alloy. A particularly preferred magnesium alloy is Resoloy®, which was developed by MeKo in Sarstedt, Germany (see WO 2013 / 024125 A1).It is an alloy of magnesium and lanthanides, particularly dysprosium. Another advantage of using magnesium and magnesium alloys is that the retention of magnesium residues in the body is physiologically unproblematic.

[0053] While the detachment point serves as the anode, the cathode can be positioned, for example, on the body surface. Alternatively, another area of ​​the device can also form the cathode. Of course, the detachment point must be electrically connected to the voltage source. The guide wire itself can serve as the conductor. Since the resulting corrosion current is controlled by the surface area of ​​the cathode when the cathode is placed on the body surface, the surface area of ​​the cathode should be chosen to be significantly larger than the surface area of ​​the anode. To a certain extent, the dissolution rate of the detachment point can be controlled by adjusting the surface area of ​​the cathode in relation to the surface area of ​​the anode. The device according to the invention can thus also comprise a voltage source and, if appropriate, an electrode that can be placed on the body surface.

[0054] As an alternative to an electrolytically dissolved detachment point, other detachment points known from the prior art can also be used, in particular mechanically, thermally, or chemically separable detachment points. Mechanical detachment typically involves a positive, force-, or frictional connection, which is broken upon release of the stent structure, causing the stent structure to detach from the guidewire or tube. Thermal detachment can break the connection by heating the detachment point, causing it to become so soft or melt that separation occurs. Finally, chemical detachment is also possible, in which detachment is brought about by a chemical reaction at the detachment point.

[0055] The different types of detachment, for example, electrolytic and mechanical detachment, can also be combined. In this case, a mechanical connection is established between the units, in particular via a positive fit, which remains until an element maintaining the mechanical connection is electrolytically corroded. At least parts of the stent structure can bear a coating that prevents the adhesion of platelets. Such an antithrombogenic coating can have a functional layer, wherein the functional layer comprises at least one sugar alcohol and / or is formed by an oligo- or polymerization of monosaccharides functionalized with polymerizable groups. Such an antithrombogenic coating is disclosed in WO 2018 / 210989 A1.

[0056] The device according to the invention can be used in particular in the neurovascular area, but it can also be used in the cardiovascular or peripheral area.

[0057] In addition to the endovascular device, the invention also relates to a method for introducing the endovascular device according to the invention into a blood vessel, wherein the device is introduced into a microcatheter and positioned such that the distal end of the guidewire protrudes distally from the microcatheter, and the microcatheter, together with the endovascular device located in the microcatheter, is advanced distally in the blood vessel. Frequently, before the endovascular device is advanced to the target position with the microcatheter, a relatively large-lumen guide catheter is first used, through which the small-lumen microcatheter is advanced further distally. In neurovascular applications, for example, the guide catheter can be advanced from the groin to the carotid artery, with further advancement then taking place solely with the microcatheter.

[0058] Furthermore, the invention also relates to a combination of an endovascular device and a microcatheter, wherein the endovascular device is placed in the microcatheter in such a way that the distal end of the guide wire protrudes distally from the microcatheter.

[0059] Finally, the invention also relates to the use of the device according to the invention for removing a thrombus from a blood vessel and a corresponding method. All descriptions of features of the invention refer to all embodiments, in particular both to the first embodiment, in which the stent structure is connected to the guidewire via the connection point, and to the alternative embodiment, in which a connection point to a tube is present, unless the context indicates otherwise.

[0060] The invention is explained in more detail using the exemplary embodiments illustrated in the figures. It should be noted that the figures show preferred embodiments of the invention; however, the invention is not limited thereto. In general, the invention encompasses, to the extent technically feasible, any combination of the technical features listed in the claims or described in the description as relevant to the invention.

[0061] They show:

[0062] Fig. 1 shows the device according to the invention according to a first embodiment in side view;

[0063] Fig.2 shows the device according to the invention according to a second embodiment in side view;

[0064] Fig. 3 shows the device according to the invention according to a third embodiment in side view and

[0065] Fig. 4 shows the device according to the invention according to an alternative embodiment in side view.

[0066] Fig. 1 shows a side view of a first embodiment of the endovascular device 1 according to the invention. The endovascular device 1 serves to capture a thrombus and essentially consists of a stent structure 2 and a guidewire 5. The stent structure 2 is shown here in the expanded state, with the guidewire 5 running along the periphery of the stent structure 2. The guidewire 5 and the stent structure 2 are connected to each other via a connection point 6, wherein in this embodiment, the connection point 6 represents a fixed connection.

[0067] The stent structure 2 has a cylindrical main section 3 and a proximal section 4 tapering towards the periphery of the stent structure 2, where the struts of the stent structure 2 terminate at the connection point 6 with the guide wire 5. The struts of the stent structure 2 form a plurality of cells 7 distributed over the outer surface of the stent structure, which cells are open in the radial direction so that they can penetrate a thrombus upon expansion. The guide wire 5 extends distally well beyond the stent structure 2 to fulfill its function of guiding the device 1 through the blood vessel system. The distal section 8 of the guide wire 5 is J-shaped to further facilitate probing and minimize the risk of blood vessel injury. To visualize the insertion and release process, the stent structure 2 is provided with radiopaque markings 9 at its distal end.

[0068] Fig. 2 shows a second embodiment of the invention. In contrast to the first embodiment, the connection point 6 here is designed as a fixed bearing, which allows rotation of the guide wire 5 relative to the stent structure 2. This further simplifies the introduction of the endovascular device 1 into the blood vessel system. Here, too, the guide wire 5 extends significantly beyond the stent structure 2 in the distal direction and has a distal section 8 with a side curvature.

[0069] Finally, Fig. 3 shows a third embodiment of the invention. Here, the connection point 6 is designed as a floating bearing, which not only enables rotation of the guide wire 5 relative to the stent structure 2, but also a limited displacement in the longitudinal direction. The longitudinal displacement is symbolized by the arrows 11 and limited by the two stops 10. This additional degree of freedom provides the attending physician with additional options when inserting and advancing the endovascular device 1 in the vascular system.

[0070] Fig. 4 shows the alternative embodiment of the invention, in which the stent structure 2 is connected via the connection point 6 not to the guidewire 5, but to a tube 12, wherein the guidewire 5 runs through the interior of the tube 12 and extends distally beyond the stent structure 2. The guidewire 5 is rotatable within the tube 12 and displaceable in the longitudinal direction. In this embodiment, too, the endovascular device 1 is placed in a microcatheter (not shown here) such that the guidewire 5 protrudes distally from the microcatheter, allowing the guidewire 5 to find its way through the blood vessel and enable probing.

Claims

Patent claims 1. Endovascular device with a stent structure (2) which exists in an expanded state, in which it is released at least temporarily into a blood vessel, and in a compressed state, in which it is inserted into the blood vessel in a microcatheter, wherein the stent structure (2) has a substantially cylindrical main section (3), characterized in that the stent structure (2) has at least one connection point (6) with a guide wire (5) and the guide wire (5) extends distally beyond the stent structure (2), wherein the guide wire (5) runs along the periphery of the stent structure (2).

2. Endovascular device according to claim 1, characterized in that the connection point (6) between the stent structure (2) and the guide wire (5) is a fixed bearing that allows rotation of the guide wire (5) relative to the stent structure (2).

3. Endovascular device according to claim 1, characterized in that the connection point (6) between the stent structure (2) and the guide wire (5) is a floating bearing that allows the guide wire (5) to be displaced in the longitudinal direction and rotated relative to the stent structure (2).

4. Endovascular device according to claim 3, characterized in that the displacement of the guide wire (5) in the longitudinal direction proximally and distally is limited by stops (10).

5. Endovascular device according to one of claims 1 to 4, characterized in that the stent structure (2) has at least two connection points (6) with the guide wire (5), wherein one connection point (6) is a fixed bearing that allows rotation of the guide wire (5) relative to the stent structure (2), and one connection point (6) is a floating bearing that allows displacement of the guide wire (5) in the longitudinal direction and rotation of the guide wire (5) relative to the stent structure (2), wherein the fixed bearing and the floating bearing are spaced apart from each other in the longitudinal direction.

6. Endovascular device with a stent structure (2) which exists in an expanded state, in which it is released at least temporarily into a blood vessel, and in a compressed state, in which it is inserted into the blood vessel in a microcatheter, wherein the stent structure (2) has a substantially cylindrical main section (3), characterized in that the stent structure (2) has at least one connection point (6) with a tube (12) through which a guide wire (5) runs, which can be brought into a position in which it extends distally beyond the stent structure (2).

7. Endovascular device according to claim 6, characterized in that the guide wire (5) runs along the periphery of the stent structure (2).

8. Endovascular device according to claim 6 or 7, characterized in that the tube (12) is made of a metal.

9. Endovascular device according to one of claims 6 to 8, characterized in that the tube (12) has slots or indentations extending substantially orthogonally or diagonally to the longitudinal direction, which increase the flexibility of the tube (12).

10. Endovascular device according to one of claims 1 to 9, characterized in that the stent structure (2) has a tapered proximal section (4) proximal to the cylindrical main section (3), which tapers towards a connection point (6) located on the periphery of the stent structure (2) with the guide wire (5) or the tube (12).

11. Endovascular device according to one of claims 1 to 10, characterized in that the guide wire (5) has a distal section (8) which is curved to the side or in a proximal direction.

12. Endovascular device according to one of claims 1 to 11, characterized in that at least parts of the distal section (8) of the guide wire (5) are radiopaque.

13. Endovascular device according to one of claims 1 to 12, characterized in that the stent structure (2) is designed to be self-expanding and, after release from a microcatheter, independently assumes the expanded state.

14. Endovascular device according to one of claims 1 to 13, characterized in that the endovascular device (1 ) is a device for removing thrombi from blood vessels.

15. Endovascular device according to one of claims 1 to 13, characterized in that the endovascular device (1 ) is an implant.

16. Endovascular device according to one of claims 1 to 15, characterized in that the connection points (6) between the stent structure (2) and the guide wire (5) or the tube (12) are designed to be separable electrolytically, mechanically, thermally or chemically.

17. Combination of an endovascular device (1 ) according to any one of claims 1 to 16 and a microcatheter, wherein the endovascular device (1 ) is placed in the microcatheter such that the distal end of the guide wire (5) protrudes distally from the microcatheter.

18. Method for introducing the endovascular device (1) according to one of claims 1 to 16 into a blood vessel, characterized in that the endovascular device (1) is inserted into a microcatheter and positioned such that the distal end of the guide wire (5) protrudes distally from the microcatheter, and the microcatheter together with the device in the microcatheter the endovascular device (1) located in the blood vessel is advanced distally.

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