Patent Description:
This invention relates to a medical device for the removal of tissue from the body. One specific use of this device is removal of blood clots (thrombus) or plaque from arteries or veins.

It is often desirable to remove tissue from the body in a minimally invasive manner as possible, so as not to damage other tissues. For example, removal of tissue (e.g., blood clots) from the vasculature may improve patient conditions and quality of life.

Many vascular system problems stem from insufficient blood flow through blood vessels. One causes of insufficient or irregular blood flow is a blockage within a blood vessel referred to as a blood clot, or thrombus. Thrombi can occur for many reasons, including after a trauma such as surgery, or due to other causes. For example, a large percentage of the more than <NUM> million heart attacks in the United States are caused by blood clots (thrombi) which form within a coronary artery.

When a thrombus forms, it may effectively stop the flow of blood through the zone of formation. If the thrombus extends across the interior diameter of an artery, it may cut off the flow of blood through the artery. If one of the coronary arteries is <NUM>% thrombosed, the flow of blood is stopped in that artery, resulting in a shortage of oxygen carrying red blood cells, e.g., to supply the muscle (myocardium) of the heart wall. Such a thrombosis is unnecessary to prevent loss of blood but can be undesirably triggered within an artery by damage to the arterial wall from atherosclerotic disease. Thus, the underlying disease of atherosclerosis may not cause acute oxygen deficiency (ischemia) but can trigger acute ischemia via induced thrombosis. Similarly, thrombosis of one of the carotid arteries can lead to stroke because of insufficient oxygen supply to vital nerve centers in the cranium. Oxygen deficiency reduces or prohibits muscular activity, can cause chest pain (angina pectoris), and can lead to death of myocardium which permanently disables the heart to some extent. If the myocardial cell death is extensive, the heart will be unable to pump sufficient blood to supply the body's life sustaining needs. The extent of ischemia is affected by many factors, including the existence of collateral blood vessels and flow which can provide the necessary oxygen.

Clinical data indicates that clot removal may be beneficial or even necessary to improve outcomes. For example, in the peripheral vasculature, inventions and procedures can reduce the need for an amputation by <NUM> percent. The ultimate goal of any modality to treat these conditions of the arterial or venous system is to remove the blockage or restore patency, quickly, safely, and cost effectively. This may be achieved by thrombus dissolution, fragmentation, thrombus aspiration or a combination of these methods.

Catheter directed thrombectomy and thrombolysis are commonly perceived to be less traumatic, less likely to decrease the morbidity and mortality associated with conventional surgical techniques. In recent years, direct administration of chemical lysing agents into the coronary arteries has shown to be of some benefit to patients who have thrombosed coronary arteries. In this procedure, a catheter is placed immediately in front of the blockage and a drip of streptokinase is positioned to be directed at the upstream side of the thrombus. Streptokinase is an enzyme which is able in time to dissolve the fibrin molecule. This procedure can take several hours and is not always successful in breaking up the thrombus. Furthermore, it can lead to downstream thrombus fragments (emboli) which can lead to blockage of small diameter branches.

Thrombectomy is a technique for mechanical removal of blood clots in an artery or vein. It refers to physically removing a clot as opposed to employing chemical lysis to dissolve it. Multiple devices have been introduced to break up and remove clot and plaque, but each has its own shortcomings. For example, <CIT> provides an angioplasty device wherein an embolic mesh filter is integrated within the catheter, designed to capture embolic particles. As the thrombectomy device is properly positioned, ribs which connect the mesh filter to the device are bowed outwards to erect the filter to trap particles. Similarly, <CIT> provides a declotting apparatus comprising one or more catheter portions with a slidable member and braided mesh jacket disposed upon a member forming a proximal and distal region. The braided mesh is composed of a plurality of deformable members which can be bowed or collapsed by sliding the catheter to expand and contract the jacket and accordingly declot the site. <CIT> discloses a "recanalization device" for removing blood clots, wherein the design comprises an expandable cage slidably coupled to an elongate wire with attached collars either side of the cage. Part of the elongate wire may be advanced through the vasculature of the patient, meanwhile the medical personnel manipulate the other end for effective contact with the clot. Specifically, the existing systems do not provide adequate methods for breaking up the clot into smaller pieces for subsequent aspiration. Also, they do not provide a method for removing the thrombectomy device over a guidewire and reinserting into the same location to complete the procedure. There is a need for an improved thrombectomy device that is more effective for removing thrombus and plaque from the vascular system.

The invention relates to a thrombectomy device as defined in claim <NUM>. Further embodiments are specified in the dependent claims. No methods of surgery or treatment are claimed.

The devices and methods disclosed herein provide an improved thrombectomy device that achieves the objective of more efficient clot removal via improved intra-arterial geometry with over-the-wire functionality. The thrombectomy devices disclosed herein remove thrombi using braided assemblies that can be expanded to a diameter of the practitioner's choosing, enabling the practitioner to custom fit the device to the particular thrombus during the procedure. Unlike conventional thrombectomy devices, the diameter of the disclosed braided assembly can be changed mid-procedure as needed, for example, should additional grip be needed for removal of the thrombus. In some embodiments, multiple braided assemblies can be used to address longer thrombi. Each braided assembly can be separately expanded, such that the individual assemblies have different diameters during the procedure.

The aspiration catheter includes a proximal end and a distal end. The retrieval device extends through the lumen of the aspiration catheter and exits at the distal end. The retrieval device includes a proximal region, a distal region, and a first lumen extending between the proximal and distal regions. At least one braided assembly extends over a distal region of the retrieval device. The at least one braided assembly includes at least one slidable collar extending circumferentially around the retrieval device and configured to slide longitudinally along the retrieval device, and a braid attached to the slidable collar. The braid can be one ply or two ply. The braid extends from the slidable collar toward a fixed attachment point that anchors the braid to the retrieval device. Upon expansion, the braid takes an elliptical or a spindle shape, having a maximum diameter near the center and narrowing as the proximal and distal regions approach the longitudinal axis of the braid.

At least one activation wire extends through the first lumen of the retrieval device and through an exit point located on the distal region. A distal end of the activation wire is attached to the slidable collar. In some embodiments, the exit point is a portal in a sidewall of the retrieval device. The portal can be positioned beneath the braid of the braided assembly, for example. In some embodiments, the retrieval device includes a proximally located hypotube and a distally located support tube that has greater flexibility than the proximal hypotube. The portal can be defined in a sidewall of the distal support tube, and the braided assembly can be positioned over the distal support tube. In some embodiments, the distal support tube is attached to the distal end of the proximal hypotube.

Applying tension to the activation wire causes the braided assembly to expand to a diameter of the practitioner's choosing. As such, the braided assembly can be expanded to a range of expanded outer diameters by varying the level of tension on the activation wire. For example, the braided assembly is deployable to a first expanded outer diameter by placing a first level of tension on the activation wire, or to a second expanded outer diameter by placing a second level of tension on the activation wire. The practitioner may apply a first level of tension to the activation wire to deploy the braided assembly to a first diameter and then later change the diameter by applying a different level of tension. In some embodiments, the first level of tension in the activation wire is less than the second level of tension in the activation wire, such that the first expanded outer diameter is the maximum diameter of the braid in a partially expanded configuration, and the second expanded outer diameter is the maximum diameter of the braid in a fully expanded configuration. The expanded braided assembly contacts the thrombus and is pulled proximally toward the aspiration catheter to assist in thrombus removal. The braid has a shape memory of the collapsed configuration, so releasing tension in the activation wire allows the braid to relax to back to the collapsed state, for example, as it enters the aspiration catheter during removal.

Some embodiments of the thrombectomy device can further include a guidewire tubing. In some embodiments, the guidewire tubing can be shorter than the retrieval device. The retrieval device extends through the first lumen of the guidewire tubing, and the second lumen of the guidewire tubing extends over a guidewire. The fixed point of attachment of the braided assembly can be located on the guidewire tubing in some embodiments. The guidewire tubing can be shorter than the retrieval device in the longitudinal direction in some embodiments.

Some embodiments of the thrombectomy device can include a braided assembly with multiple braided sections and multiple sliding collars. In these embodiments, each additional slidable collar is positioned between two braided sections. Tensioning the activation wire causes at least partial expansion of each of the braided sections. The multiple braided sections can be formed of one continuous braid, or they can be formed of separate braids. In some embodiments, the activation wire is attached to one of multiple slidable collars. For example, the activation wire may be attached to the distal-most slidable collar.

Some embodiments of the thrombectomy device include at least one additional braided assembly and at least one additional activation wire. Each additional activation wire is attached to an additional slidable collar of an additional braided assembly, such that each braided assembly is separately expandable via an attached activation wire.

Some embodiments of the thrombectomy device include a proximally located tensioning element for controlling the activation wire that expands the braided assembly. The proximal end of the activation wire is attached to a tensioning element, which can be attached to a proximally located handle, for example.

Methods of performing thrombectomy procedures are also disclosed herein, but do not form part of the claimed invention. The methods include advancing the distal end of the aspiration catheter through the vasculature to an area proximal to a thrombus, and advancing the distal end of the retrieval device carrying at least one braided assembly out of the distal end of the aspiration catheter and to a position distal to the thrombus. A first level of tension is applied to the activation wire that attaches to the braided assembly. The first level of tension moves the activation wire longitudinally within a lumen of the retrieval device, thereby moving the slidable collar of the braided assembly longitudinally over an exterior surface of the retrieval device and deploying the braided assembly to a first expanded outer diameter. If desired, a second level of tension, either greater or smaller than the first level of tension, can be applied to the activation wire. The second level of tension moves the activation wire longitudinally within the lumen of the retrieval device, thereby moving the slidable collar of the braided assembly longitudinally over the exterior surface of the retrieval device and deploying the braided assembly to a second expanded outer diameter. The distal end of the retrieval device maintains a stationary position as the slidable collar moves longitudinally over the exterior surface of the retrieval device and the braided assembly is expanded to the optimal diameter. In some embodiments, the second level of tension opens the braided assembly to a wider second expanded outer diameter to more firmly contact the thrombus with the braid. The thrombus is pulled toward the aspiration catheter and aspirated into the distal end of the aspiration catheter. In some embodiments, the thrombus is aspirated into the distal end of the aspiration catheter using an external vacuum source.

In some embodiments of the methods, which are not covered by the claimed invention, the thrombus can be contacted and pulled using multiple braided sections or multiple braided assemblies. For example, movement of a single slidable collar can cause expansion of more than one braided section of a braided assembly. In another example, a proximally positioned braided assembly can collapse from a first expanded outer diameter to a narrower second outer diameter as it approaches the distal end of the aspiration catheter, while a distally positioned braided assembly can maintain an expanded outer diameter that is equivalent to or wider than the second outer diameter of the proximally positioned braided assembly.

Some embodiments of the methods, which are not covered by the claimed invention, can include the use of a guidewire. These methods include advancing the guidewire to a position distal to the thrombus prior to advancing the distal end of the retrieval device. The retrieval device can extend at least partially through a first lumen of a guidewire tubing, and the method includes advancing the guidewire tubing with the retrieval device over the guidewire. The activation wire moves longitudinally within the retrieval device, which is in the first lumen of the guidewire tubing. The guidewire moves longitudinally within a second lumen of the guidewire tubing.

Other examples, features, aspects, embodiments, and advantages will become apparent to those skilled in the art from the following description. As will be realized, the device and/or methods are capable of other different and obvious aspects.

For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.

Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein provided they align with the scope of the claims. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive or where such combinations do not align with the scope of the claims.

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) provided said features or combinations thereof align with the scope of the claims.

As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. The terms "about" and "approximately" are defined as being "close to" as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within <NUM>%. In another non-limiting embodiment, the terms are defined to be within <NUM>%. In still another non-limiting embodiment, the terms are defined to be within <NUM>%.

Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises," means "including but not limited to," and is not intended to exclude, for example, other additives, components, integers or steps. "Exemplary" means "an example of" and is not intended to convey an indication of a preferred or ideal aspect. "Such as" is not used in a restrictive sense, but for explanatory purposes.

Certain terminology is used in the following description for convenience only and is not limiting. The words "right," "left," "lower," and "upper" designate direction in the drawings to which reference is made. The words "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of the described feature or device. The words "distal" and "proximal" refer to directions taken in context of the item described and, with regard to the instruments herein described, are typically based on the perspective of the practitioner using such instrument, with "proximal" indicating a position closer to the practitioner and "distal" indicating a position further from the practitioner. The terminology includes the above-listed words, derivatives thereof, and words of similar import.

The thrombectomy devices disclosed herein remove a thrombus using a braided assembly that can be expanded to a diameter of the practitioner's choosing, enabling the practitioner to custom fit the device to the particular vessel and thrombus and during the procedure. Unlike conventional thrombectomy devices, the diameter of the disclosed braided assembly can be changed mid-procedure as needed. For example, the braided assembly can be opened to a wider diameter to apply more outward force against the thrombus should additional grip be needed for its removal. In some embodiments, multiple braided assemblies can be used to address longer thrombi. Each braided assembly can be separately expanded, such that the individual assemblies have different diameters during the procedure.

The device disclosed herein is used to the remove a thrombus, clot, or plaque from the veins or arteries of the body. It includes an aspiration catheter and a retrieval device that extends through the lumen of the aspiration catheter. An expandable braided assembly extends over a distal region of the retrieval device, such that when the retrieval device exits the distal end of the aspiration catheter, the braided assembly is positioned outside of the aspiration catheter. An activation wire extends through the lumen of the retrieval device. The distal end of the activation wire exits the retrieval device at an exit point to connect to and control the expansion of a braided assembly. On the proximal end, the activation wire is attached to a tensioning element. Applying tension to the activation wire causes the braided assembly to expand to a diameter of the practitioner's choosing. For example, the practitioner may apply a first level of tension to deploy the braided assembly to a first, partially expanded configuration and then later decide to widen the diameter to the fully expanded configuration by applying a greater level of tension to the activation wire. The expanded braided assembly contacts the thrombus, clot, or plaque and is pulled proximally toward the aspiration catheter to assist in removal. Hereinafter the device and methods will be described as removing (or being configured to remove) a thrombus. However, it will be understood that the device can also be used to remove clots or plaques from the vasculature with no structural (or only slight structural) modifications. Various embodiments of the thrombectomy catheter include a retrieval device with multiple braided assemblies, multiple activation wires, multiple braided sections of a single braided assembly, and retrieval devices with multiple lumens to, for example, enable use with a guidewire.

<FIG> show an embodiment of the thrombectomy device <NUM>. <FIG> shows the aspiration catheter <NUM>, the retrieval device <NUM>, a collapsed braided assembly <NUM>, and a guidewire tip <NUM>. The aspiration catheter <NUM> is an elongated tube with reinforced construction that allows a vacuum to be applied at the proximal end to pull clot and emboli out of the artery or vein without collapsing. The aspiration catheter <NUM> can be formed of a polymer material. The aspiration catheter <NUM> can include an imaging marker <NUM> (such as a fluorescent or radiopaque marker) for use in imaging the position of the catheter during a procedure. Thrombus retrieval device <NUM> extends through aspiration catheter <NUM>. The braided assembly <NUM> extends over a distal region <NUM> of the retrieval device <NUM>, such that when the retrieval device <NUM> exits the distal end <NUM> of the aspiration catheter <NUM>, the braided assembly <NUM> is positioned outside of the aspiration catheter <NUM>. In the collapsed configuration, braided assembly <NUM> is sized and configured for insertion through the aspiration catheter <NUM> and into an artery or vein. Guidewire tip <NUM> extends distally from the distal end <NUM> of the retrieval device <NUM>. The guidewire tip <NUM> can be flexible, shapeable, and steerable.

The braided assembly <NUM> is moveable from a collapsed to an expanded configuration. An example of a braided assembly <NUM> in an expanded configuration is shown in <FIG>, but the maximum diameter, dmax, of the expanded braided assembly <NUM> can be changed to any value over a continuous range, from a fully collapsed diameter, to a partially expanded diameter, to a fully expanded diameter. The maximum diameter of the braided assembly, dmax, is the widest point measured perpendicular to a longitudinal axis, a, extending through the center of the braided assembly <NUM>. The braided assembly <NUM> can be sized and configured to disrupt and capture one or more clots, plaques, and/or thrombi and pull them toward the aspiration catheter <NUM> where they can be removed. The braided assembly <NUM> includes a braid <NUM>, a slidable collar <NUM>, and a fixed attachment point <NUM> where the braid <NUM> anchors to the retrieval device <NUM>. The braid <NUM> may be attached directly to the retrieval device <NUM> at attachment point <NUM>, or the braid <NUM> may be attached indirectly to the retrieval device <NUM> at attachment point <NUM>. In some embodiments, the fixed attachment point <NUM> is a fixed collar that extends around the retrieval device <NUM>, and the braid is welded, bonded, or otherwise adhered to the fixed collar. Regardless, at the fixed attachment point <NUM>, the braid <NUM> does not move longitudinally relative to the retrieval device <NUM>.

The opposite end of braid <NUM> is welded, bonded, or otherwise adhered to slidable collar <NUM>. In the embodiments shown, the slidable collar <NUM> is slidably connected to the retrieval device <NUM> by virtue of its annular shape, which extends circumferentially around the retrieval device <NUM>. The slidable collar <NUM> slides longitudinally along the retrieval device <NUM> as braid <NUM> is expanded and collapsed. The slidable collar <NUM> can be positioned distally to the fixed attachment point <NUM> (a distal position), as shown in <FIG>, or the slidable collar <NUM> can be positioned proximally to the fixed attachment point <NUM> (a proximal position). In some embodiments, slidable collar <NUM> or fixed attachment point <NUM> can include a marker that can be viewed using imaging modalities during a procedure. For example, the slidable collar <NUM> or fixed attachment point <NUM> can include a fluorescent or radiopaque label.

The braid <NUM> is composed of multiple strands of wire. The braid <NUM> takes an elliptical or a spindle shape when expanded, having a maximum diameter dmax at or near the center of the braid <NUM> and narrowing as the braid approaches the fixed attachment point <NUM> and the slidable collar <NUM>. The wires are formed of a shape memory material such as, but not limited to, shape memory polymers or shape memory metals (e.g., nitinol). The braid <NUM> has a baseline shape memory of the collapsed configuration, which forms a cylindrical structure around the retrieval device <NUM>, as shown in <FIG>. In the activated, expanded configuration, the braid <NUM> has a tendency to relax toward the collapsed configuration.

When the practitioner is pulling a thrombus or plaque proximally toward aspiration catheter <NUM> using braided assembly <NUM>, the braid <NUM> encounters distally oriented drag forces that are strongest along the widest portions (for example, the central region of the braid adjacent dmax). These drag forces resist the proximally oriented pulling force exerted by the practitioner. The distal end of braid <NUM> at slidable collar <NUM> will encounter less drag force while being pulled proximally because the radial force it exerts on the radially adjacent vasculature or thrombus is small, negligible, or non-existent. If the braid is not properly designed, the sliding collar <NUM> and distal end of the braid <NUM> will invert into the wider, central regions of the braid <NUM>. Inversion during the procedure can be prevented by optimizing factors such as the pic count (crosses per inch), the wire diameter, the number of wires, and the ply of the braid (sets of overlapping braids). Higher pic counts increase flexibility, while lower pic counts increase longitudinal stiffness. Likewise, a braid with more than one ply (multiple sets of braids nested within each other), will be stiffer than a single-ply braid. Braids can be one-ply, two-ply, three-ply, or more. Braids with more wires will be stiffer than those with fewer wires, and braids with wider diameter wires will be stiffer than those with narrow diameter wires. Wires of varying diameters can be used within the same braid <NUM>.

The design of the braided assemblies <NUM> disclosed herein may vary based on whether the device <NUM> is intended for an arterial procedure or for a venous procedure, since the procedure site will be wider in a venous setting. For example, a braid <NUM> designed for a venous application may have a dmax of from about <NUM> to <NUM> (<NUM> inches to <NUM> inches), including about <NUM> (<NUM> inches) , about <NUM> (<NUM> inches), about <NUM> (<NUM> inch), about <NUM> (<NUM> inches), and about <NUM> (<NUM> inches). For venous applications, a braid <NUM> may have a wire diameter range from about <NUM> × <NUM>-<NUM> m to about <NUM> × <NUM>-<NUM> m (<NUM> inches to about <NUM> inches), including <NUM> × <NUM>-<NUM> m (<NUM> inches), <NUM> × <NUM>-<NUM> m (<NUM> inches), <NUM> ×<NUM>-<NUM> m (<NUM> inches), <NUM> × <NUM>-<NUM>m (<NUM> inches), <NUM> × <NUM>-<NUM> m (<NUM> inches), <NUM> × <NUM>-<NUM> m (<NUM> inches), and <NUM> × <NUM>-<NUM> m (<NUM> inches). Different wires of the braid <NUM> may have different diameters, or they may have the same diameter. In some venous embodiments, the diameters of the wires of the braid <NUM> are <NUM> ×<NUM>-<NUM> m (<NUM> inches), <NUM> ×<NUM>-<NUM> m (<NUM> inches), and/or <NUM> × <NUM>-<NUM> m (<NUM> inches). Two-ply braids can utilize smaller wire diameters without sacrificing the radial force that can be applied. The pic count can be from <NUM> to <NUM> for venous applications. In some embodiments used in venous applications, the pic count is <NUM>, <NUM>, or <NUM>. The number of wires per braid for a venous application can be anywhere from <NUM> to <NUM>, including <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>.

Braids for venous applications were tested using a selection of the above listed venous application parameters. End points included the expansion force and the radial outward force applied by the braid to the inner surface of a tubing that simulates a vein (the tubing having an inner diameter of <NUM> millimeters). The expansion force is the force required to open the braid, as applied to the activation wire. The data is shown below in Table <NUM>.

For arterial applications, the braid <NUM> can have dmax of from about <NUM> to about <NUM> (<NUM> inches to about <NUM>), including about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches) , about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches), about <NUM> (<NUM> inches) and about <NUM> (<NUM> inches). For example, the braid <NUM> can have a dmax of about <NUM> (<NUM> inches), <NUM> (<NUM> inches), or <NUM> (<NUM> inches). The diameter of the wires of the braid <NUM> for an arterial application can range from about <NUM> × <NUM>-<NUM> m to about <NUM> × <NUM>-<NUM> m (<NUM> inches to about <NUM> inches), including about <NUM> × <NUM>-<NUM> m (<NUM> inches), about <NUM> × <NUM> -<NUM> m (about <NUM> inches), about <NUM> × <NUM>-<NUM> m (<NUM> inches), about <NUM> × <NUM>-<NUM> m (<NUM> inches), about <NUM> × <NUM>-<NUM> m (<NUM> inches), about <NUM> × <NUM>-<NUM> m (<NUM> inches), and about <NUM> × <NUM>-<NUM> m (<NUM> inches). Different wires of the braid <NUM> may have different diameters, or they may have the same diameter. In some arterial embodiments, the diameters of the wires of braid <NUM> are <NUM> × <NUM>-<NUM> m (<NUM> inches), <NUM> × <NUM>-<NUM> m (<NUM> inches) and/or <NUM> × <NUM>-<NUM> m (<NUM> inches). Two-ply braids can utilize smaller wire diameters without sacrificing the radial force that can be applied. The pic count can be from <NUM> to <NUM> for arterial applications, including a pic count of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM>. In some embodiments used in arterial applications, the pic count is <NUM>, <NUM>, or <NUM>. The number of wires per braid <NUM> for an arterial application can be anywhere from <NUM> to <NUM>, including <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In some embodiments, the number of wires per braid <NUM> for an arterial application is <NUM>, <NUM>, or <NUM>.

Braids for arterial applications were tested using a selection of the above listed arterial application parameters. End points included the radial outward force applied by the braid to the inner surface of a tubing (the tubing having an inner diameter of <NUM> millimeters), and the proximal force needed to pull the braid through a restriction in the tubing (the inner diameter of the restriction being <NUM> millimeters). The tubing and the restriction simulate an artery and a thrombus/plaque, respectively. Favorable prototypes give a high radial outward force without requiring excessive force to pull the braid through the restriction. The data is shown below in Table <NUM>. All braids tested were one-ply.

The activation wire <NUM> extends through the lumen of the retrieval device <NUM>, exits the retrieval device <NUM> at exit point <NUM>, and extends distally along the exterior surface of the retrieval device <NUM>. The distal end <NUM> of the activation wire <NUM> is attached to slidable collar <NUM>. As such, the activation wire <NUM> is able to control the expansion and collapse of the braid <NUM> via the slidable collar <NUM>. The distance between exit point <NUM> and slidable collar <NUM> affects the length that the slidable collar can be pulled along retrieval device <NUM> to open the braided assembly <NUM>. If it is too close to slidable collar, the braided assembly <NUM> will not be able to open fully. As such, exit point <NUM> should be positioned proximally far enough from the unexpanded position of slidable collar <NUM> to enable the braided assembly <NUM> to open to its maximum outer diameter. <FIG> shows the embodiment of <FIG> without braid <NUM> to facilitate viewing the activation wire <NUM> and the activation wire exit point <NUM>. ID is a cross sectional view of activation wire <NUM> in retrieval device <NUM>, taken at line A-A of <FIG>. The internal positioning of the proximal regions of the activation wire <NUM> (within retrieval device <NUM>) is advantageous in that no friction or bulk is added by the system that controls expansion of the braided assembly <NUM>.

The proximal region of activation wire <NUM> (not shown) may be tensioned and released to control the expansion and collapse of the braided assembly <NUM> via movement of slidable collar <NUM>. Under tension, the activation wire <NUM> moves proximally within the lumen of the retrieval device <NUM> as it translates the tension from the proximal region of the activation wire <NUM> to the braided assembly <NUM>. In implementations where the slidable collar <NUM> is in the distal position (as shown), the exit point <NUM> of the activation wire is located proximally to the slidable collar <NUM>. The exit point <NUM> can be, for example, a portal in the sidewall of retrieval device <NUM>. Use of a slidable collar <NUM> to expand the braided assembly <NUM> is advantageous because the distal end of the braided assembly <NUM> can be moved while the distal region <NUM> of the retrieval device <NUM> maintains a constant position within the vasculature. Maintaining a constant position of the distal region <NUM> of retrieval device <NUM> is advantageous because sliding proximal/distal movement of the distal region <NUM> within the vessel can result in vessel damage or perforation.

In implementations where the slidable collar <NUM> is in the proximal position relative to the fixed attachment point (not shown), the activation wire <NUM> extends distally past the slidable collar <NUM> inside the retrieval device <NUM>, exits the retrieval device <NUM> at exit point <NUM>, then doubles back and extends along the exterior surface of the retrieval device <NUM> to attach to the proximally located slidable collar <NUM>. The exit point <NUM> can be a portal in the sidewall of the retrieval device as described above, or the exit point <NUM> can be the distal end <NUM> of the retrieval device <NUM>.

Retrieval device <NUM> can include a proximal hypotube <NUM> and a distal support tube <NUM>, as shown in <FIG>. In some embodiments, the hypotube <NUM> extends through the support tube <NUM>. However, the distal region can be made more flexible by attaching the proximal end of the distal support tube <NUM> to the distal end <NUM> of the proximal hypotube <NUM> (for example, by adhesive bonding, heat bonding, or welding processes). The fixed attachment point <NUM> of the braided assembly <NUM> can be located on distal support tube <NUM> and the slidable collar <NUM> can extend around the distal support tube <NUM>, such that the braided assembly <NUM> is positioned over and around the distal support tube <NUM>. The braided assembly <NUM> can alternatively be positioned only partially over the distal support tube (i.e., one of the fixed attachment point <NUM> or the slidable collar <NUM> is attached to the proximal hypotube <NUM>, and the other of the fixed attachment point or the slidable collar <NUM> is attached to the distal support tube <NUM>). In some embodiments, the support tube <NUM> serves to increase the overall diameter of the retrieval device <NUM>, for example, to accommodate a larger diameter braid and to encapsulate the guidewire tip <NUM>. The distal support tube <NUM> can also provide a lower friction surface for movement of the slidable collar <NUM> than the proximal hypotube <NUM> would provide.

In some embodiments, distal support tube <NUM> has greater flexibility than the proximal hypotube <NUM>. For example, the distal support tube <NUM> can be made of a polymer material, while the proximal hypotube <NUM> is made of a more rigid metal material. In some embodiments, the proximal hypotube <NUM> is constructed from metal hypodermic needle tubing. The hypotube <NUM> can be up to <NUM> times stiffer than the support tube <NUM>. There are several advantages to having a distal support tube <NUM> with greater flexibility than proximal hypotube <NUM>. The greater flexibility of the support tube <NUM> enables a gradual transition in flexibility between the hypotube <NUM> and the guidewire tip <NUM>. In some scenarios, the greater flexibility of the distal support tube <NUM> can facilitate movement of the braided assembly <NUM> through a tortuous thrombus. The greater flexibility can promote kink resistance. The greater flexibility of the distal support tube <NUM> can also facilitate the introduction of a portal or exit point <NUM> during the production of the device. The higher rigidity of the hypotube <NUM> (as compared to support tube <NUM>) is important because it allows the retrieval device <NUM> to be pushed through the vasculature. The rigidity of hypotube <NUM> also helps to ensure that the braided assembly <NUM> can be pushed through a thrombus or plaque.

On the proximal end, the activation wire <NUM> can be attached to a tensioning element (not shown) that allows the activation wire <NUM> to be moved forward or retracted backward within the retrieval device <NUM>. Applying tension to the activation wire <NUM> causes the slidable collar <NUM> to move and causes the braided assembly <NUM> to expand to a diameter of the practitioner's choosing. Similarly, releasing tension on the activation wire <NUM> allows the braided assembly <NUM> to relax into the collapsed, baseline configuration.

In some embodiments, such as the one shown in <FIG>, the device includes a proximal handle <NUM>. The handle <NUM> is coupled to a proximal end of retrieval device <NUM>. The tensioning element is a knob <NUM> that is coupled to the proximal end of activation wire <NUM> on the inside of the handle. Actuation of the knob <NUM> in one direction causes the activation wire <NUM> to be tensioned (expanding the braided assembly), and actuation of the knob <NUM> in the opposite direction releases tension on the activation wire <NUM> (collapsing the braided assembly). In other embodiments, the tensioning element can include a slider, ratcheting mechanism, or lever. The aspiration catheter <NUM> terminates in a y-adaptor (not shown) that separates the lumen of the aspiration catheter to be connected to a vacuum source for removal of the clot or emboli and allows the activation wire to be connected to the handle <NUM>.

Another embodiment of a proximal handle <NUM> is shown in <FIG>. The handle <NUM> of <FIG> is advantageous in that it enables a practitioner to lock the braided assembly <NUM> at a fixed outer diameter. This can be useful, for example, when pushing and pulling the device through a thrombus. As shown in <FIG>, proximal handle <NUM> is coupled to a proximal end of retrieval device <NUM>. Activation wire <NUM> extends proximally past the proximal end retrieval device <NUM> and into proximal handle <NUM>. Strain relief section <NUM> is formed of a flexible material that prevents kinking of the retrieval device <NUM> just distal to the handle <NUM>. Proximal handle <NUM> also includes a tensioning element in the form of locking slider <NUM>, which slides proximally and distally within groove <NUM> and can be locked in place to secure the outer diameter of the braided assembly <NUM> during a procedure. The underside of locking slider <NUM> and groove <NUM> is shown in <FIG>, and a cross sectional view of locking slider and groove <NUM> is shown in <FIG>. Locking slider <NUM> includes a sliding portion <NUM> and a lock button <NUM>. As seen in <FIG>, downward pointing teeth <NUM> extend downward from the inner surface <NUM> of the outer casing <NUM> of handle <NUM>, from a position adjacent the groove <NUM>. The lock button <NUM> includes an exterior portion <NUM> with a textured gripping surface. The lock button <NUM> extends downward through sliding portion <NUM>, and includes an interior portion <NUM>. The interior portion <NUM> of the lock button <NUM> extends away from the exterior portion <NUM> of lock button <NUM> in a direction that is perpendicular to the longitudinal axis A-A of the locking slider <NUM>. Interior portion <NUM> includes upward facing teeth <NUM> that are configured to engage with the downward facing teeth <NUM> of the outer casing <NUM> of the handle <NUM>. Spring <NUM>, which is vertically positioned within slider <NUM>, beneath the exterior surface <NUM> of lock button <NUM>, exerts an upward force on lock button <NUM> to hold the upward facing teeth <NUM> in a locked configuration with the downward facing teeth <NUM> of the outer casing <NUM>. When lock button <NUM> is compressed, the spring <NUM> is compressed and the teeth <NUM>, <NUM> disengage. With the lock button <NUM> pressed and the teeth <NUM>, <NUM> disengaged, proximal or distal force can be applied to sliding portion <NUM> to move the locking slider <NUM> within the groove <NUM>. An interior portion <NUM> of the sliding portion <NUM> grips the activation wire <NUM>. As the locking slider <NUM> is moved within groove <NUM>, the activation wire <NUM> is moved proximally or distally to affect the expansion or allow the collapse of the braided assembly <NUM>.

Conventional thrombectomy devices utilize shape memory elements with a baseline expanded configuration. These conventional devices risk inadvertent overexpansion and damage to the vessel. Furthermore, conventional devices are often restrained by a bulky overlying sheath, which is pulled back to allow the device to self-expand.

Advantageously, using a device with a shape memory of the collapsed position reduces the risk of overexpansion and injury during self-expansion. Self-collapse also allows the device to be restrained using the low-profile activation wire system described herein. An additional advantage is the ability to expand the braided assembly to various diameters to precisely custom fit the size of the vessel. This can be especially useful if the size of the vessel is different than originally anticipated. The level of grip between the braid <NUM> and the surrounding thrombus can also be customized as needed by applying different levels of tension to the activation wire <NUM>. For example, the practitioner may apply a first level of tension to deploy the braided assembly <NUM> to a first expanded outer diameter to contact the thrombus. If the force between the thrombus and the braid <NUM> is not enough to pull the thrombus toward the aspiration catheter <NUM>, the practitioner can widen the braid <NUM> to a second expanded outer diameter by applying a greater second level of tension to the activation wire <NUM>. This widened diameter provides a greater contact force between the thrombus and the braid <NUM>, such that the thrombus can be more easily pulled toward aspiration catheter <NUM>.

<FIG> show an additional embodiment of a thrombectomy device having a braided assembly <NUM> with multiple braided sections <NUM>, <NUM>. The elongated nature of this embodiment facilitates the capture and retrieval of long thrombi. As shown in <FIG>, ach of the braided sections <NUM>, <NUM> is attached to and extends around the distal region <NUM> of retrieval device <NUM>. The braided assembly <NUM> includes multiple sliding collars <NUM>, <NUM> and a fixed attachment point <NUM>. Proximal braided section <NUM> is attached to and extends between the fixed attachment point <NUM> and the proximal slidable collar <NUM>, where it is welded, bonded, or otherwise adhered at a central sliding attachment point <NUM>. Distal braided section <NUM> is attached to and extends between the proximal slidable collar <NUM> and the distal slidable collar <NUM>. In some embodiments, the braided sections are formed by constraining one larger braid with the proximal slidable collar <NUM>. In other embodiments, each braided section is formed from a separate braid (such that each of the proximal and distal braided assemblies are separately fixedly attached to proximal slidable collar <NUM>). In some embodiments, the slidable collars <NUM>, <NUM> can be positioned distally to the fixed attachment point <NUM>, as illustrated in <FIG>. In other embodiments, the slidable collars can be positioned proximally to the fixed attachment point (not shown). Though illustrated with two braided sections <NUM>, <NUM>, other embodiments of the braided assembly <NUM> could include more than two braided sections and more than two slidable collars.

<FIG> shows the thrombectomy device of <FIG> without the braided assembly <NUM>. Retrieval device <NUM> has a hypotube <NUM> fixedly attached to a support tube <NUM>. A single activation wire <NUM> extends through hypotube <NUM> and support tube <NUM> to an exit point <NUM> positioned on the support tube <NUM>. From there, it travels along the outer surface of support tube <NUM>, running beneath proximal sliding collar <NUM> to attach to distal sliding collar <NUM>. Cross sectional views shown in <FIG> show the radial position of activation wire <NUM> with respect to hypotube <NUM>, the support tube <NUM>, and the guidewire tip <NUM> at various axial locations along the thrombectomy device shown in <FIG>. The activation wire <NUM> is utilized to control expansion of the braided assembly via connection to the distal sliding collar <NUM>. In other embodiments, the activation wire <NUM> can be attached to the proximal sliding collar <NUM>. retrieval device. Proximal movement of the proximal slidable collar <NUM> or the distal slidable collar <NUM> by the activation wire generates a force on the other of the two slidable collars, such that the two braided sections <NUM>, <NUM> are expanded (or partially expanded) in unison. As described above, the braids are formed of a shape memory material with a bias toward the collapsed configuration, so that tensioning the activation wire enables multiple levels of expansion.

<FIG> shows an additional embodiment with multiple, separately expandable braided assemblies <NUM>, <NUM>. The braided assemblies <NUM>, <NUM> are spaced from each other along the distal region <NUM> of retrieval device <NUM>. The proximal braided assembly <NUM> includes braided section <NUM> that extends between a fixed attachment point <NUM> and a slidable collar <NUM>. The distal braided assembly <NUM> includes braided section <NUM> that extends between a fixed attachment point <NUM> and a slidable collar <NUM>. Each braided assembly is controlled by a separate activation wire, such that each braided assembly can be individually controlled. Each activation wire exits the retrieval device <NUM> from an exit point beneath the individual braid and attaches to the individual slidable collar (not shown). The multiple activation wires can travel through the same lumen in retrieval device <NUM>, or they could have individual lumens. Depending upon the positioning of the slidable collars in relation to the fixed attachment points, in some embodiments, each additional activation wire can travel through the same lumen and exit the retrieval device at the same portal, or at different portals. In some embodiments, one or more activation wires can exit from the distal end of the retrieval device <NUM>.

As with the previously described embodiments, the braids of the embodiment shown in <FIG> are formed of a shape memory material with a bias toward the collapsed configuration, such that tensioning the activation wire enables deployment of the braid to a range of diameters. Each braided assembly is deployable to a partially expanded configuration by placing a first level of tension in the attached activation wire, or to a fully expanded configuration by placing a second, greater level of tension into the activation wire. Thus, when multiple activation wires and braided assemblies are used, a first braided assembly can be deployed to a partially expanded state while a second braided assembly is deployed in a fully expanded state. In some scenarios, it may be advantageous for one braided assembly to be fully collapsed while another braided assembly is either partially or fully expanded. This can be advantageous, for example, when pulling a longer thrombus into the aspiration catheter <NUM>. The proximal braided section <NUM> can be collapsed as it enters the aspiration catheter, prior to the distal braided section <NUM> which is still outside of the aspiration catheter.

In some embodiments, braids of separate braided sections or separate braided assemblies can have different properties, such as different maximum expanded diameters, different wire sizes, different wire densities, different numbers of wires, etc. These properties can vary depending upon the positioning of the braided section or the braided assembly along the retrieval device. For example, the distal braided section or braided assembly might have a larger expanded diameter to better pull back against the thrombus, while the proximal braided section(s) or braided assembly(s) might be less dense and stronger to better engage the middle of the thrombus.

<FIG> show an embodiment of the thrombectomy device that enables use with a guidewire, such that a practitioner can remove and reinsert the device to the same anatomic position multiple times (for example, to clean the device during the procedure). <FIG> shows aspiration catheter <NUM>, retrieval device <NUM>, guidewire tubing <NUM>, braided assembly <NUM> (in the collapsed configuration), and guidewire <NUM>. Guidewire tubing <NUM> is positioned around the distal region <NUM> of retrieval device <NUM>. The guidewire tubing <NUM> is shorter than the retrieval device <NUM> in the longitudinal direction, such that the guidewire <NUM> leaves the guidewire tubing <NUM> at the proximal guidewire exit <NUM> and extends alongside retrieval device in a proximal direction. <FIG> shows the embodiment of <FIG> with the braided assembly <NUM> in an expanded state. As shown in the cross section of <FIG> taken at line B-B of <FIG>, guidewire <NUM> extends through the first lumen <NUM> of the guidewire tubing <NUM>. The guidewire <NUM> exits guidewire tubing <NUM> at distal guidewire exit <NUM>. The guidewire tubing <NUM> can include a distal atraumatic tip <NUM>. The guidewire tubing <NUM> can be formed, for example, of a polymer material. Retrieval device <NUM>, including activation wire <NUM>, extends through a second lumen <NUM> of the guidewire tubing <NUM>. As described above, the activation wire <NUM> is connected on the proximal end to a tensioning element, extends through retrieval device <NUM> to an exit point, leaves the retrieval device <NUM> at the exit point (beneath the braid), and attaches at its distal end to the slidable distal collar <NUM> on the braided assembly <NUM>. The exit point can be, for example, a tunnel through the sidewalls of the retrieval device <NUM> and the guidewire tubing <NUM> (i.e., a tunnel formed by a portal in the sidewall of the retrieval device <NUM> that is aligned/coaxial with a portal in the sidewall of the guidewire tubing <NUM>). In use, the guidewire tubing <NUM> and the retrieval device <NUM> are introduced together over the previously placed vascular guidewire <NUM>. Because the guidewire <NUM> is retained within the guidewire tubing <NUM>, it is pulled at least partially to the side within the lumen of aspiration catheter <NUM> and can move without interfering with activation wire <NUM>. The guidewire tubing <NUM> and the retrieval device <NUM> keep the activation wire <NUM> and the guidewire <NUM> moving in an axial direction, independently from one another, using a low-profile and low-friction design. Once in position, the braided assembly <NUM> is expanded and the proximal end of the aspiration catheter <NUM> is connected to a vacuum source. The braided assembly <NUM> is expanded and then retracted back toward the aspiration catheter <NUM>, pulling the clot with it and breaking it into small pieces.

Methods of performing thrombectomy procedures are also disclosed herein, but do not form part of the claimed invention. An example method is illustrated in <FIG> illustrates thrombus <NUM> occluding vessel <NUM>. Distal end of aspiration catheter <NUM> is advanced through the vasculature to an area proximal to the thrombus <NUM>, as shown in <FIG>. The distal end of retrieval device <NUM> carrying braided assembly <NUM> is advanced out the distal end of the aspiration catheter <NUM> and through thrombus <NUM>, such that the braided assembly <NUM> is distal to thrombus <NUM>, as shown in <FIG>. The practitioner then places tension in the activation wire housed inside the retrieval device <NUM>, thereby moving the activation wire longitudinally within the lumen of the retrieval device and moving the slidable collar of the braided assembly longitudinally over the exterior surface of the retrieval device. Movement of the slidable collar via the activation wire causes braided assembly <NUM> to expand to the diameter of the practitioner's choosing. Should the practitioner wish to alter the level of expansion during the procedure (i.e., change the maximum diameter d of the braided assembly <NUM>), this is made possible by altering the level of tension in the activation wire, which again moves the activation wire within the retrieval device and moves the slidable collar, as described above. Advantageously, the distal end of the retrieval device <NUM> maintains a stationary position as the braided assembly is expanded to the optimal diameter. Maintaining a constant position of the distal end of retrieval device <NUM> is advantageous because sliding proximal/distal movement of the distal end within the vessel can result in vessel damage or perforation.

<FIG> shows the braided assembly <NUM> in an expanded configuration, sized to fit the vessel <NUM>. The practitioner then pulls the retrieval device <NUM> proximally and contacts the thrombus <NUM> with the braided assembly <NUM>, as shown in <FIG>. The thrombus <NUM> and braided assembly <NUM> are pulled proximally toward aspiration catheter <NUM>. The aspiration catheter <NUM> can be connected to an external vacuum source (not shown), which enables the aspiration of the thrombus <NUM> into the distal end of the aspiration catheter <NUM>. The aspiration catheter <NUM> is then retracted proximally, as illustrated in <FIG>, and removed from the body.

The ability to open the braided assembly to a range of different diameters is useful to thrombectomy procedures for multiple reasons and in multiple scenarios. The ability to custom fit the braid to a particular vessel during the procedure is preferable over introducing a braid that expands to a predetermined size, then discovering mid-procedure that it is either too small to grip the thrombus or that it is too large and has damaged the vessel. As another exemplary advantage, the level of grip between the braid and the thrombus can be optimized mid-procedure. For example, the practitioner may apply a first level of tension to the activation wire to deploy the braided assembly to a first expanded outer diameter to contact the thrombus. If the force between the thrombus and the braid is not sufficient to pull the thrombus toward the aspiration catheter, the practitioner can widen the braid to a second expanded outer diameter by applying a greater second level of tension to the activation wire. This widened diameter increases the contact force between the thrombus and the braid, such that the thrombus is more easily pulled toward aspiration catheter.

The methods, which do not form part of the claimed invention, can also be performed using a guidewire. For example, the guidewire can be positioned distal to the thrombus prior to advancing the distal end of the retrieval device. The retrieval device extends at least partially through a lumen of the guidewire tubing, such as in the embodiment of <FIG>. Together, the retrieval device and guidewire tubing are advanced over the guidewire and toward the thrombus. The guidewire extends through a separate lumen of the guidewire tubing than the retrieval device and activation wire. Once positioned, the activation wire is moved longitudinally within the retrieval device to expand the braided assembly.

Long thrombi can be addressed using braided assemblies with multiple braided sections such as the embodiment shown in <FIG>. Movement of the slidable collar results in expansion of more than one of the braided sections, resulting in a relatively long braided assembly. In some embodiments a device with multiple, separately expandable braided assemblies, such as the one shown in <FIG>, can be used to treat long thrombi. With separately expandable braided assemblies, as the thrombus is drawn proximally closer to the distal end of the aspiration catheter, the proximally positioned braided assembly collapses from a first expanded outer diameter to the collapsed diameter (or to a narrower second expanded outer diameter). The distally positioned braided assembly maintains an expanded outer diameter that is greater than the outer diameter of the proximally positioned braided assembly until it too is pulled into the aspiration catheter.

Claim 1:
A thrombectomy device (<NUM>) comprising:
an aspiration catheter (<NUM>) comprising a proximal end and a distal end (<NUM>);
a retrieval device (<NUM>) configured to extend through the aspiration catheter (<NUM>) and
exit at the distal end (<NUM>), the retrieval device (<NUM>) comprising a proximal region, a distal region (<NUM>), and a first lumen extending therebetween;
at least one braided assembly (<NUM>) extending over the distal region (<NUM>) of the retrieval device (<NUM>), the braided assembly (<NUM>) comprising at least one slidable collar (<NUM>), and a braid (<NUM>), the slidable collar (<NUM>) extending circumferentially around the retrieval device (<NUM>) and configured to slide longitudinally along the retrieval device (<NUM>), the braid (<NUM>) attached to the slidable collar (<NUM>) and extending from the slidable collar (<NUM>) to a fixed attachment point (<NUM>) that anchors the braid (<NUM>) to the retrieval device (<NUM>); and
at least one activation wire (<NUM>) extending through the first lumen of the retrieval device (<NUM>) and through an exit point (<NUM>) located on the distal region (<NUM>), wherein a distal end (<NUM>) of the activation wire (<NUM>) is attached to the slidable collar (<NUM>);
wherein the braid (<NUM>) has a shape memory of a collapsed configuration; and
wherein the braided assembly (<NUM>) can be expanded to a range of expanded outer diameters by varying the level of tension on the activation wire (<NUM>).