Patent Description:
Many medical procedures use medical devices to remove an obstruction (such as clot material) from a body lumen, vessel, or other organ. An inherent risk in such procedures is that mobilizing or otherwise disturbing the obstruction can potentially create further harm if the obstruction or a fragment thereof dislodges from the retrieval device. If all or a portion of the obstruction breaks free from the device and flows downstream, it is highly likely that the free material will become trapped in smaller and more tortuous anatomy. In many cases, the physician will no longer be able to use the same retrieval device to again remove the obstruction because the device may be too large and/or immobile to move the device to the site of the new obstruction.

Procedures for treating ischemic stroke by restoring flow within the cerebral vasculature are subject to the above concerns. The brain relies on its arteries and veins to supply oxygenated blood from the heart and lungs and to remove carbon dioxide and cellular waste from brain tissue. Blockages that interfere with this blood supply eventually cause the brain tissue to stop functioning. If the disruption in blood occurs for a sufficient amount of time, the continued lack of nutrients and oxygen causes irreversible cell death. Accordingly, it is desirable to provide immediate medical treatment of an ischemic stroke.

To access the cerebral vasculature, a physician typically advances a catheter from a remote part of the body (typically a leg) through the abdominal vasculature and into the cerebral region of the vasculature. Once within the cerebral vasculature, the physician deploys a device for retrieval of the obstruction causing the blockage. Concerns about dislodged obstructions or the migration of dislodged fragments increases the duration of the procedure at a time when restoration of blood flow is paramount. Furthermore, a physician might be unaware of one or more fragments that dislodge from the initial obstruction and cause blockage of smaller more distal vessels.

Many physicians currently perform thrombectomies (i.e. clot removal) with stents to resolve ischemic stroke. Typically, the physician deploys a stent into the clot in an attempt to push the clot to the side of the vessel and re-establish blood flow. Tissue plasminogen activator ("tPA") is often injected into the bloodstream through an intravenous line to break down a clot. However, it takes time for the tPA to reach the clot because the tPA must travel through the vasculature and only begins to break up the clot once it reaches the clot material. tPA is also often administered to supplement the effectiveness of the stent. Yet, if attempts at clot dissolution are ineffective or incomplete, the physician can attempt to remove the stent while it is expanded against or enmeshed within the clot. In doing so, the physician must effectively drag the clot through the vasculature, in a proximal direction, into a guide catheter located within vessels in the patient's neck (typically the carotid artery). While this procedure has been shown to be effective in the clinic and easy for the physician to perform, there remain some distinct disadvantages to using this approach.

For example, one disadvantage is that the stent may not sufficiently retain the clot as it pulls the clot to the catheter. In such a case, some or all of the clot might remain in the vasculature. Another risk is that, as the stent mobilizes the clot from the original blockage site, the clot might not adhere to the stent as the stent is withdrawn toward the catheter. This is a particular risk when passing through bifurcations and tortuous anatomy. Furthermore, blood flow can carry the clot (or fragments of the clot) into a branching vessel at a bifurcation. If the clot is successfully brought to the end of the guide catheter in the carotid artery, yet another risk is that the clot may be "stripped" or "sheared" from the stent as the stent enters the guide catheter.

In view of the above, there remains a need for improved devices and methods that can remove occlusions from body lumens and/or vessels.

<CIT> describes a distal element comprising an expandable mesh. a treatment device includes an elongated member having a proximal portion and a distal portion configured to be positioned within a blood vessel at a treatment site at or near a thrombus.

<CIT> describes an electrically enhancing attachment of the material to the removal device. The removal device can have a core assembly that includes a hypotube coupled to a first electrical terminal and a pushwire coupled to a second electrical terminal, the pushwire extending through the hypotube lumen.

<CIT> describes an obstruction removal device is described having a retrieval component used to engage an obstruction within the vasculature and a sheath component that is capable of inverting to fold over the obstruction and the retrieval component. The sheath component helps contain the obstruction and minimizes trauma to the blood vessel during the removal process.

<CIT> describes a flexible catheter device capable of being introduced into body passages, withdraw fluids therefrom or introduce fluids thereinto, and which includes electrodes configured to apply electrical signals in the body passage for carrying out thrombus dissolution and/or thrombectomy, wherein one of said electrodes is designed to contact the thrombus material and remove it or dissolve it, and wherein the electrical voltage signals are a unipolar pulsatile voltage signal.

<CIT> describes an apparatus (<NUM>) for removal of a thrombus from a body of a subject. The apparatus includes a first electrode (<NUM>), made of a first conductive metal having a first electronegativity, and a second electrode (<NUM>), made of a second conductive metal having a second electronegativity that is less than the first electronegativity.

Mechanical thrombectomy (e.g., clot-grabbing and removal) has been effectively used for treatment of ischemic stroke. Although most clots can be retrieved in a single pass attempt, there are instances in which multiple attempts are needed to fully retrieve the clot and restore blood flow through the vessel. Additionally, there exist complications due to detachment of the clot from the interventional element during the retrieval process as the interventional element and clot traverse through tortuous intracranial vascular anatomy. For example, the detached clot or clot fragments can obstruct other arteries leading to secondary strokes. The failure modes that contribute to clot release during retrieval are: (a) boundary conditions at bifurcations; (b) changes in vessel diameter; and (c) vessel tortuosity, amongst others. Certain blood components, such as platelets and coagulation proteins, display negative electrical charges. The treatment systems of the present technology provide an interventional element and a current generator configured to positively charge the interventional element during one or more stages of a thrombectomy procedure. For example, the current generator may apply a constant or pulsatile direct current (DC) to the interventional element. The positively charged interventional element attracts negatively charged blood components, thereby improving attachment of the thrombus to the interventional element and reducing the number of device passes or attempts necessary to fully retrieve the clot. In some aspects of the present technology, the treatment system includes an elongate core assembly (e.g., a cable) extending between the current generator and the interventional element. A delivery electrode may be integrated into the core assembly and/or interventional element, and the treatment system further includes a negative electrode that may be disposed at a number of different locations. For example, the negative electrode can be a wire coupled to or integrated within the core assembly. Additionally or alternatively, a negative electrode can take the form of a needle, a grounding pad, a conductive element carried by a one or more catheters of the treatment system, a separate guide wire, and/or any other suitable conductive element configured to complete an electrical circuit with the delivery electrode and the extracorporeally positioned current generator. When the interventional element is placed in the presence of blood (or any other electrolytic medium) and voltage is applied at the terminals of the current generator, current flows along the core assembly to the interventional element, through the blood, and to the return electrode, thereby positively charging at least a portion of the interventional element and adhering clot material thereto.

One approach to delivering current to an interventional element is to conduct current along a core member coupled to a proximal end of the interventional element. However, the inventors have discovered that this approach can lead to disadvantageous concentration of electrical charge along a proximal portion of the interventional element, with insufficient charge density in more distal portions of the interventional element (e.g., along some or all of the working length of the interventional element). This is particularly true of an interventional element having a proximal portion that tapers to a connection point with the core member. This concentration of current in the proximal portion can reduce the efficacy of electrostatic enhancement of clot adhesion, as the mechanical clot engagement occurs primarily at a location distal to the region at which the charge density is greatest. Additionally, when used in an aqueous chloride environment, such as the blood, hydrogen and chlorine gas bubbles can form along the surface of the interventional element in areas with high surface charge density (e.g., along a proximal portion of the interventional element). To reduce risk to the patient and ensure the treatment system functions properly, it may be beneficial to ensure that current flows through the entire interventional element, particularly ensuring sufficient current density in distal portions of the interventional element. When the entire interventional element exhibits a positive electrical charge, all portions of the interventional element can attract negatively charged blood components, thereby improving attachment of the thrombus to the interventional element. If portions of the interventional element are not positively charged (e.g., the distal portion is electrically neutral or exhibits insufficient charge density), those portions of the interventional element may not adequately attract negatively charged blood components, which can prevent improved attachment of the thrombus to the interventional element.

Embodiments of the present technology address these and other problems by providing an electrically conductive coating to one or more components of the treatment system. The conductive coating can be applied to an outer surface of the interventional element. By coating the interventional element with an electrically conductive material, current can easily be distributed through the interventional element instead of concentrating at the more proximal portions of the interventional element. Additionally or alternatively, a conductive coating can be applied to a distal end portion of the core assembly. The core assembly can take the form of an elongated conductor, such as a wire, and be positioned in relation to the interventional element such that the coated distal end portion is positioned distally of the interventional element's distal end. Positioning the interventional element and core assembly in this manner, along with applying a conductive coating to the core assembly and/or interventional element, encourages current to flow through all portions of the interventional element and thereby allows for the interventional element to reliably maintain a positive charge during treatment.

Additional features and advantages of the present technology are described below, and in part will be apparent from the description, or may be learned by practice of the present technology. The advantages of the present technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. The subject technology is illustrated, for example, according to various aspects described below. These various aspects are provided as examples and do not limit the subject technology.

In one embodiment, a medical device is described. The medical device can include a core assembly configured to be advanced within a corporeal lumen. The core assembly can include a first conductor having a proximal end portion and a distal end portion, the first conductor forming a lumen; a second conductor at least partially disposed within the lumen of the first conductor, the second conductor comprising a first conductive material and having a proximal end portion and a distal end portion extending distal to the distal end portion of the first conductor; an insulative material disposed over at least a portion of the second conductor, the insulative material defining one or more uninsulated portions of the second conductor; and a second conductive material surrounding the second conductor along at least part of the one or more uninsulated portions, the second conductive material having a higher electrical conductivity than the first conductive material. The medical device can also include an interventional element coupled to the distal end portion of the first conductor, the interventional element being electrically coupled to the first conductor, the interventional element comprising a body formed of a third conductive material; and a fourth conductive material disposed over at least a portion of the third conductive material of the interventional element, the fourth conductive material having a higher electrical conductivity than the third conductive material.

In some embodiments, the second conductive material and the fourth conductive material are the same. In some embodiments, the second conductive material and the fourth conductive material each comprises gold. In some embodiments, the distal portion of the second conductor defines a distal tip having an enlarged radial dimension.

In one embodiment, a medical device is described. The medical device can include an elongated shaft having a proximal portion configured to be electrically coupled to a terminal of a current generator, an intermediate portion at least partially covered with an insulative material, and a distal portion, the elongated shaft comprising a first conductive material; an elongated tubular member having a proximal portion configured to be electrically coupled to a current generator, a distal portion, and a lumen receiving the elongated shaft therethrough such that the distal portion of the elongated shaft extends distal to the distal portion of the elongated tubular member; an interventional element coupled to the distal portion of the elongated tubular member, the interventional element at least partially surrounding the distal portion of the elongated shaft, the interventional element comprising a second conductive material; an insulative material disposed over at least a portion of the elongated shaft, the insulative material defining one or more uninsulated portions of the elongated shaft; a third conductive material surrounding the distal portion of the elongated shaft along at least a part of its length, the conductive material being configured to increase the electrical conductivity of the distal portion of the elongated shaft; and a fourth conductive material surrounding the interventional element along at least a part of its length, the fourth conductive material being configured to increase the electrical conductivity of the interventional element.

In some embodiments, the third conductive material has a higher electrical conductivity than the first conductive material. In some embodiments, the fourth conductive material has a higher electrical conductivity than the second conductive material. In some embodiments, the third conductive material is positioned radially adjacent to or distal of the interventional element.

In some embodiments, the third conductive material and the fourth conductive material are the same. In some embodiments, the third conductive material and the fourth conductive material each comprises gold. In one embodiment, a method for delivering an electrical current to a treatment device is described. The method can include inserting a treatment device into a patient, the treatment device comprising: a core assembly comprising: a first conductor having a proximal end portion and a distal end portion, the first conductor forming a lumen; a second conductor at least partially disposed within the lumen of the first conductor, the second conductor comprising a first conductive material and having a proximal end portion and a distal end portion extending distal to the distal end portion of the first conductor; an insulative material disposed over at least a portion of the second conductor, the insulative material defining one or more uninsulated portions of the second conductor; and a second conductive material surrounding the second conductor along at least part of the one or more uninsulated portions, the second conductive material having a higher electrical conductivity than the first conductive material. The treatment device can further include an interventional element coupled to the distal end portion of the first conductor of the core assembly, the interventional element being electrically coupled to the first conductor, the interventional element comprising a body formed of a third conductive material; and a fourth conductive material disposed over at least a portion of the third conductive material of the interventional element, the fourth conductive material having a higher electrical conductivity than the third conductive material. The method can further include positioning the treatment device proximate a thrombus within a lumen of a blood vessel at a treatment site; and delivering an electrical current to the treatment device.

In some embodiments, the second conductive material is positioned radially adjacent to or distal of the interventional element. In some embodiments, the second conductive material and the fourth conductive material are the same. In some embodiments, the second conductive material and the fourth conductive material each comprises gold. In some embodiments, the method further includes ceasing delivery of the electrical current to the treatment device after a time period.

Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Instead, emphasis is placed on clearly illustrating the principles of the present disclosure.

The present technology provides devices, systems, and methods for removing clot material from a blood vessel lumen. Although many of the embodiments are described below with respect to devices, systems, and methods for treating a cerebral or intracranial embolism, other applications and other embodiments, in addition to those described herein, are within the scope of the technology. For example, the treatment systems and methods of the present technology may be used to remove emboli from body lumens other than blood vessels (e.g., the digestive tract, etc.) and/or may be used to remove emboli from blood vessels outside of the brain (e.g., pulmonary, abdominal, cervical, or thoracic blood vessels, or peripheral blood vessels including those within the legs or arms, etc.). In addition, the treatment systems and methods of the present technology may be used to remove luminal obstructions other than clot material (e.g., plaque, resected tissue, foreign material, etc.). In some embodiments, aspects of the present technology can be applied to medical devices and systems that are not configured for removal of material from vessel lumens, for example systems and devices for ablation, neuromodulation, or any other suitable medical procedure.

<FIG> illustrates a view of an electrically enhanced treatment system <NUM> according to one or more embodiments of the present technology. As shown in <FIG>, the treatment system <NUM> can include a current generator <NUM> and a treatment device <NUM> having a proximal portion 104a configured to be coupled to the current generator <NUM> and a distal portion 104b configured to be intravascularly positioned within a blood vessel (such as an intracranial blood vessel) at a treatment site at or proximate a thrombus. The treatment device <NUM> includes an interventional element <NUM> at the distal portion 104b, a handle <NUM> at the proximal portion 104a, and a plurality of elongated shafts or members extending therebetween. For example, in some embodiments, such as that shown in <FIG>, the treatment device <NUM> includes a first catheter <NUM> (such as a guide catheter or balloon guide catheter), a second catheter <NUM> (such as a distal access catheter or aspiration catheter) configured to be slidably disposed within a lumen of the first catheter <NUM>, and a third catheter <NUM> (such as a microcatheter) configured to be slidably disposed within a lumen of the second catheter <NUM>. In some embodiments, the treatment device <NUM> can include a core assembly <NUM> extending between the proximal portion 104a and distal portion 104b of the treatment device <NUM>. In some embodiments, the treatment device <NUM> does not include the first catheter <NUM> and/or the second catheter <NUM>.

The core assembly <NUM> is configured to be slidably disposed within the lumen of the third catheter <NUM>. In the illustrated embodiment, the core assembly <NUM> can take the form of an electrical cable or other such assembly that includes a first electrical conductor <NUM> and a second electrical conductor <NUM>. As discussed in more detail below, in some instances the first conductor <NUM> can take the form of an elongated tube (e.g., a hypotube) made of or including an electrically conductive material, and the second conductor <NUM> can take the form of an elongated wire or rod that is made of or includes an electrically conductive material. In some embodiments, the second conductor <NUM> is configured to be disposed within a lumen of the first conductor <NUM>. In some embodiments, the first conductor <NUM> and second conductor <NUM> are coaxial. In various embodiments, the first conductor <NUM> and second conductor <NUM> are non-slidably coupled together. The first conductor <NUM> and second conductor <NUM> can be sized and configured to be advanced through a corporeal lumen to the treatment site. For example, the first conductor <NUM> and second conductor <NUM> can be sized to be positioned proximate a thrombus within a lumen of a blood vessel, such as within a patient's neurovasculature. The first conductor <NUM> and/or the second conductor <NUM> can be electrically insulated along at least a portion of their respective lengths. In some embodiments, the first catheter <NUM> can be coupled to (or incorporate) the handle <NUM>, which provides proximal access to the first conductor <NUM> and second conductor <NUM>.

<FIG> are schematic views of different embodiments of the current generator <NUM>. With reference to <FIG>, the current generator <NUM> can include a power source <NUM>, a first terminal <NUM>, a second terminal <NUM>, and a controller <NUM>. The controller <NUM> includes a processor <NUM> coupled to a memory <NUM> that stores instructions (e.g., in the form of software, code or program instructions executable by the processor or controller) for causing the power source <NUM> to deliver electric current according to certain parameters provided by the software, code, etc. The power source <NUM> of the current generator <NUM> may include a direct current power supply, an alternating current power supply, and/or a power supply switchable between a direct current and an alternating current. The current generator <NUM> can include a suitable controller that can be used to control various parameters of the energy output by the power source or generator, such as intensity, amplitude, duration, frequency, duty cycle, and polarity. For example, the current generator <NUM> can provide a voltage of about <NUM> volts to about <NUM> volts and a current of about <NUM> mA to about <NUM> mA.

<FIG> illustrates another embodiment of the current generator <NUM>, in which the controller <NUM> of <FIG> is replaced with drive circuitry <NUM>. In this embodiment, the current generator <NUM> can include hardwired circuit elements to provide the desired waveform delivery rather than a software-based generator of <FIG>. The drive circuitry <NUM> can include, for example, analog circuit elements (e.g., resistors, diodes, switches, etc.) that are configured to cause the power source <NUM> to deliver electric current via the first and second terminals <NUM>, <NUM> according to the desired parameters. For example, the drive circuitry <NUM> can be configured to cause the power source <NUM> to deliver periodic waveforms via the first and second terminals <NUM>, <NUM>.

The current generator <NUM> may be coupled to the core assembly <NUM> to deliver electrical current to the interventional element <NUM> and thereby provide an electrically charged environment at the distal portion 104b of the treatment device <NUM>. Further, the current generator <NUM> may be coupled to the core assembly <NUM> to return electrical current from the electrically charged environment to the current generator <NUM>. In various embodiments, the current generator <NUM> can be electrically coupled to the first conductor <NUM>, the second conductor <NUM>, or both.

In some embodiments, the treatment system <NUM> includes a suction source <NUM> (e.g., a syringe, a pump, etc.) configured to be fluidically coupled (e.g., via a connector <NUM>) to a proximal portion of one or more of the first catheter <NUM>, the second catheter <NUM>, and/or the third catheter <NUM> to apply negative pressure therethrough. In some embodiments, the treatment system <NUM> includes a fluid source <NUM> (e.g., a fluid reservoir, a syringe, pump, etc.) configured to be fluidically coupled (e.g., via the connector <NUM>) to a proximal portion of one or more of the first catheter <NUM>, the second catheter <NUM>, and/or the third catheter <NUM> to supply fluid (e.g., saline, contrast agents, a drug such as a thrombolytic agent, etc.) to the treatment site.

According to some embodiments, the catheters <NUM>, <NUM>, and <NUM> can each be formed as a generally tubular member extending along and about a central axis. According to some embodiments, the third catheter <NUM> is generally constructed to track over a conventional guidewire in the cervical anatomy and into the cerebral vessels associated with the brain and may also be chosen according to several standard designs that are generally available. Accordingly, the third catheter <NUM> can have a length that is at least <NUM> long, and more particularly may be between about <NUM> and about <NUM> long. Other designs and dimensions are contemplated.

The second catheter <NUM> can be sized and configured to slidably receive the third catheter <NUM> therethrough. As noted above, the second catheter <NUM> can be coupled at a proximal portion to a suction source <NUM> (<FIG>) such as a pump or syringe in order to supply negative pressure to a treatment site. The first catheter <NUM> can be sized and configured to slidably receive both the second catheter <NUM> and the third catheter <NUM> therethrough. In some embodiments, the first catheter <NUM> is a balloon guide catheter having an inflatable balloon or other expandable member surrounding the catheter shaft at or near its distal end. In operation the first catheter <NUM> can first be advanced through a vessel and then its balloon can be expanded to anchor the first catheter <NUM> in place and/or arrest blood flow from areas proximal of the balloon, e.g., to enhance the effectiveness of aspiration performed via the first catheter <NUM> and/or other catheter(s). Alternatively, a guide catheter without a balloon can be employed. Next, the second catheter <NUM> can be advanced through the first catheter <NUM> until its distal end extends distally beyond the distal end of the first catheter <NUM>. The second catheter <NUM> can be positioned such that its distal end is adjacent or proximal of a treatment site (e.g., a site of a blood clot within the vessel). The third catheter <NUM> may then be advanced through the second catheter <NUM> until its distal end extends distally beyond the distal end of the second catheter <NUM>. The interventional element <NUM> may then be advanced through the third catheter <NUM> via the core assembly <NUM> for delivery to the treatment site.

According to some embodiments, the bodies of the catheters <NUM>, <NUM>, and <NUM> can be made from various thermoplastics, e.g., polytetrafluoroethylene (PTFE or TEFLON®), fluorinated ethylene propylene (FEP), high-density polyethylene (HDPE), polyether ether ketone (PEEK), etc., which can optionally be lined on the inner surface of the catheters or an adjacent surface with a hydrophilic material such as polyvinylpyrrolidone (PVP) or some other plastic coating. Additionally, either surface can be coated with various combinations of different materials, depending upon the desired results.

In some embodiments, the current generator <NUM> may be coupled to a proximal portion of the first conductor <NUM>, and/or a proximal portion of the third catheter <NUM>, the second catheter <NUM>, and/or first catheter <NUM> to provide an electric current to the interventional element <NUM>. For example, as shown in <FIG>, the current generator <NUM> can be coupled to a proximal portion of the core assembly <NUM> and/or the first conductor <NUM> such that the first conductor <NUM> functions as a first conductive path (e.g., as a positive conductive path transmitting current from the current generator to the treatment site). As shown in <FIG>, the current generator <NUM> can also be coupled to a proximal portion of the second conductor <NUM> such that the second conductor <NUM> functions as a second conductive path (e.g., as a negative conductive path transmitting current from the treatment site to the current generator <NUM>). In other embodiments, the negative electrode can be separate from the second conductor <NUM>. In some embodiments, the positive electrode can comprise the interventional element <NUM>, and the negative electrode can be carried by one or more of the third catheter <NUM>, the second catheter <NUM>, and/or first catheter <NUM>, or be coupled to or formed by a portion of the second conductor <NUM>. In some embodiments, the negative electrode can be provided via one or more external electrodes, such as a needle puncturing the patient, or a grounding pad applied to the patient's skin; in some such embodiments, or otherwise, the first conductor <NUM> or the second conductor <NUM> may be omitted from the core assembly <NUM>.

The system can include multiple (e.g., two or more), distinct conductive paths or channels for passing electrical current along the system. The interventional element <NUM> can serve as one electrode (e.g., a positive electrode) in electrical communication with a conductive path via the first conductor <NUM>. Another of the conductive paths of the system can be in electrical communication with another electrode (e.g., a negative electrode). For example, the second conductor <NUM> can serve as the second conductive path, with one or more uninsulated portions of the second conductor <NUM> forming the negative electrode(s).

As shown in <FIG>, the first conductor <NUM> and the interventional element <NUM> can be joined at a connection <NUM> to secure the interventional element <NUM> relative to the first conductor <NUM> and to complete an electrical pathway between the elongate first conductor <NUM> and the interventional element <NUM>. As illustrated in <FIG>, the distal end portion of the second conductor <NUM> is configured to be positioned distal of the distal end portion of the first conductor <NUM>. The interventional element <NUM> can be metallic or otherwise electrically conductive so that when the interventional element <NUM> is placed in the presence of blood (or thrombus, and/or any other electrolytic medium which may be present, such as saline) and voltage is applied via the electrical connectors of the current generator <NUM>, current flows from the positive connector of the current generator <NUM>, distally along the first conductor <NUM> to the interventional element <NUM> and through the surrounding media (e.g., blood, tissue, thrombus, etc.) before returning proximally along the second conductor <NUM> to the negative electrical connector of the current generator <NUM>, thereby positively charging at least a portion of the interventional element <NUM> and promoting clot adhesion.

In certain embodiments, the polarities of the current generator <NUM> can be switched, so that the negative electrical connector is electrically coupled to the first conductor <NUM> and the positive electrical connector is electrically coupled to the second conductor <NUM>. This can be advantageous when, for example, attempting to attract predominantly positively charged material to the interventional element <NUM>, or when attempting to break up a clot rather than grasp it with an interventional element <NUM>. In some embodiments alternating current (AC) signals may be used rather than DC. In certain instances, AC signals may advantageously help break apart a thrombus or other material.

In various embodiments, the interventional element <NUM> can take any number of forms, for example a removal device, a thrombectomy device, or other suitable medical device. For example, in some embodiments the interventional element <NUM> may be a stent and/or stent retriever, such as Medtronic's Solitaire™ Revascularization Device, Stryker Neurovascular's Trevo® ProVue™ Stentriever, or other suitable devices. In some embodiments, the interventional element <NUM> may be a coiled wire, a weave, and/or a braid formed of a plurality of braided filaments. Examples of suitable interventional elements <NUM> include any of those disclosed in <CIT>, <CIT>, <CIT>, and <CIT>.

The interventional element <NUM> can have a low-profile, constrained or compressed configuration for intravascular delivery to the treatment site within the third catheter <NUM>, and an expanded configuration for securing and/or engaging clot material and/or for restoring blood flow at the treatment site. The interventional element <NUM> has a proximal portion including an attachment portion 106a that may be coupled to the first conductor <NUM> and a distal portion comprising an open cell framework or body 106b. In some embodiments, the body 106b of the interventional element <NUM> can be generally tubular (e.g., cylindrical), and the proximal portion of the interventional element <NUM> can taper proximally to the attachment portion 106a. In various embodiments, the interventional element <NUM> can define a lumen that is located radially inward from the body 106b.

The interventional element <NUM> can be a metallic and/or electrically conductive thrombectomy device. For example, the interventional element can include or be made of stainless steel, nitinol, cobalt-chromium, platinum, tantalum, alloys thereof, or any other suitable material. In some embodiments, the interventional element <NUM> is a mesh structure (e.g., a braid, a stent, etc.) formed of a superelastic material (e.g., Nitinol) or other resilient or self-expanding material configured to self-expand when released from the third catheter <NUM>. The mesh structure may include a plurality of struts and open spaces between the struts. In some embodiments, the struts and spaces may be situated along the longitudinal direction of the interventional element <NUM>, the radial direction, or both.

In some embodiments, the first conductor <NUM> can be a structural element configured to push and pull a device such as the interventional element <NUM> along the bodily lumen. The first conductor <NUM> can be any suitable elongate member configured to advance the interventional element <NUM> to a treatment site within a blood vessel. For example, the first conductor <NUM> can be or include a wire, tube (e.g., a hypotube), coil, or any combination thereof. According to some embodiments, the first conductor <NUM> comprises an elongate tubular member defining a lumen therethrough. In some embodiments, the first conductor <NUM> can comprise a distally located aperture configured to receive the attachment portion of the interventional element. In some embodiments, the first conductor <NUM> comprises a distally located joining element comprising the aperture configured to receive the attachment portion. The first conductor <NUM> can have a length sufficient to extend from a location outside the patient's body through the vasculature to a treatment site within the patient's body. The first conductor <NUM> can be a monolithic structure or formed of multiple joined segments. In some embodiments, the first conductor <NUM> can comprise a laser-cut hypotube having a spiral cut pattern (or other pattern of cut voids) formed in its sidewall along at least a portion of its length. The first conductor <NUM> can be metallic and/or otherwise electrically conductive to deliver current from the current generator <NUM> to the interventional element <NUM>. For example, the first conductor <NUM> can comprise or consist of nickel titanium alloy, stainless steel, or other metals or alloys. In embodiments that comprise multiple joined segments, the segments may be of the same or different materials. For example, some or all of the first conductor <NUM> can be formed of stainless steel, or other suitable materials known to those skilled in the art. Nickel titanium alloy may be preferable for kink resistance and reduction of imaging artifacts.

In some embodiments, the second conductor <NUM> can be a structural element configured to secure or retain a position of the interventional element <NUM> relative to the first conductor <NUM>. Additionally, or alternatively, the second conductor <NUM> can be configured to be a negative electrode. The second conductor <NUM> can be any suitable elongate member configured to extend through a lumen of the first conductor <NUM>. For example, the second conductor <NUM> can be or include a wire, tube (e.g., a hypotube), coil, or any combination thereof. The second conductor <NUM> can have a length sufficient to extend from a location outside the patient's body through the vasculature to a treatment site within the patient's body. The second conductor <NUM> can be a monolithic structure or formed of multiple joined segments. The second conductor <NUM> can be metallic or electrically conductive to deliver current from the surrounding media (e.g., blood, tissue, thrombus, etc.) to the current generator <NUM>. For example, the second conductor <NUM> can comprise or consist of nickel titanium alloy, stainless steel, or other metals or alloys. In embodiments that comprise multiple joined segments, the segments may be of the same or different materials. For example, some or all of the second conductor <NUM> can be formed of stainless steel, or other suitable materials known to those skilled in the art. Nickel titanium alloy may be preferable for kink resistance and reduction of imaging artifacts. The second conductor <NUM> can be electrically insulated along some or all of its length. In some embodiments, the second conductor <NUM> comprises an insulated wire or guide wire having one or more exposed, electrically conductive portions. For example, a distal end portion of the second conductor <NUM> can be exposed to conduct current from surrounding media (e.g., blood, tissue, thrombus, etc.) at a treatment site.

In some embodiments, the treatment device <NUM> can comprise one or more electrically insulating materials. For example, an insulating material can be disposed on one or more portions of the second conductor <NUM> to electrically isolate the second conductor <NUM> from the first conductor <NUM>, the connection <NUM>, and/or the interventional element <NUM>. Additionally or alternatively, an insulating material can be disposed within a lumen of the first conductor <NUM> to electrically isolate the first conductor <NUM> from the second conductor <NUM> and/or the attachment portion of the interventional element <NUM>. In various embodiments, an insulating material is disposed over an outer surface of the interventional element <NUM> along at least a portion of the length of the interventional element <NUM>. In some embodiments, an insulating material is disposed over an outer surface of the first conductor <NUM> along at least a portion of a length of the first conductor <NUM> to direct current through the first conductor <NUM> and prevent current loss from the first conductor <NUM> to the surrounding environment. As shown in <FIG>, in some embodiments, an insulating material <NUM> can be disposed adjacent to a proximal end portion 116a and/or a distal end portion 116b of the first conductor <NUM>. The insulating material <NUM> may be disposed along an entire length of the first conductor <NUM> and/or the second conductor <NUM> or the insulating material may be disposed along select portions of the first conductor <NUM> and/or the second conductor <NUM>. The insulating material <NUM> may comprise a polymer, such as polyimide, parylene, PTFE, or another suitable electrically insulating material.

As shown in <FIG> and <FIG>, the interventional element <NUM> and the first conductor <NUM> can be coupled at a connection <NUM>. According to some embodiments, the interventional element <NUM> and the first conductor <NUM> can be substantially permanently attached together at the connection <NUM>. That is, the interventional element <NUM> and the first conductor <NUM> can be attached together in a manner that, under the expected use conditions of the device, the interventional element <NUM> and the first conductor <NUM> would not become unintentionally separated from one another. In some embodiments, the treatment device <NUM> can comprise a portion, located proximally or distally of the connection <NUM>, that is configured for selective detachment of the interventional element <NUM> from the first conductor <NUM>. For example, such a portion can comprise an electrolytically severable segment of the first conductor <NUM>. In some embodiments, the device can be devoid of any feature that would permit selective detachment of the interventional element <NUM> from the first conductor <NUM>. The connection <NUM> can provide a mechanical interlock between the interventional element <NUM> and the first conductor <NUM>. Moreover, the connection <NUM> can be configured to complete an electrically conductive path between the interventional element <NUM> and the elongate first conductor <NUM>.

<FIG> illustrates an enlarged perspective view of the connection <NUM>, according to some embodiments, between the first conductor <NUM> and the interventional element <NUM>. In some embodiments, for example as shown in <FIG>, the first conductor <NUM> comprises a distally located joining element <NUM> including an aperture <NUM> configured to receive a proximally located attachment portion 106a of the interventional element <NUM> and/or at least a portion of the second conductor <NUM>. As shown in <FIG>, the attachment portion 106a of the interventional element <NUM> is configured to mechanically interlock with a joining element <NUM> to secure the interventional element <NUM> to the core assembly <NUM>. In some embodiments, the second conductor <NUM> can be disposed within the aperture at a radially adjacent position relative to the attachment portion 106a to facilitate such securement. Further, the second conductor <NUM> may be affixed to the joining element <NUM> via a weld, an adhesive, a threaded connection, an interference fit, or any other suitable connection.

In some embodiments, the connection <NUM> can comprise a bonding agent in addition or alternative to the joining element <NUM> and/or second conductor <NUM>. The bonding agent can comprise adhesive, solder, welding flux, brazing filler, etc., disposed within the joining element <NUM>, and/or adjacent to it, just proximal of and/or just distal of the joining element <NUM>. In some embodiments, the bonding agent can bond to the connection <NUM> without applying heat. For example, the bonding agent can comprise a UV-curable adhesive. In embodiments that comprise a polymer coating of the wire or polymer tubing, use of a bonding agent that avoids application of heat that would damage the polymer may be preferred.

<FIG> is a plan view of the interventional element <NUM>, depicted in an unfurled or flattened configuration for ease of understanding. The interventional element <NUM> has a proximal portion that may be coupled to the first conductor <NUM> and a distal portion. The interventional element <NUM> has a proximal portion including an attachment portion 106a that may be coupled to the first conductor <NUM> and a distal portion comprising an open cell framework or body 106b. The attachment portion 106a of the interventional element <NUM> can have a substantially constant thickness, such as would result from the interventional element <NUM> being cut from a tube or sheet of material, for example. In other embodiments, the thickness of the attachment portion 106a can vary across its length, width, or both.

<FIG> illustrate two cross-sectional views of the interventional element <NUM> along the lines 2B and 2C in <FIG>, respectively. As illustrated in <FIG>, the interventional element <NUM> can include an insulating material <NUM> and a conductive material <NUM> coupled to the interventional element <NUM>. The conductive material <NUM> can be disposed over an outer surface of the interventional element <NUM> along at least a portion of the length of the interventional element <NUM>. The insulating material <NUM> can be disposed over an outer surface of the conductive material <NUM> so that the conductive material <NUM> is radially disposed between the interventional element <NUM> and the insulating material <NUM>. In some embodiments, one or more portions of the interventional element <NUM> are uninsulated, which exposes the underlying conductive material <NUM>. For example, as illustrated in <FIG>, the outer surface of the conductive material <NUM> is uninsulated, exposing the conductive material <NUM>. In various embodiments, one or more portions of the interventional element <NUM> do not include a conductive material <NUM> disposed over the outer surface. For example, some portions of the interventional element <NUM> can include an insulating material <NUM> disposed over the outer surface of the body 106b with no intervening conductive material <NUM> disposed between the insulating material <NUM> and the body 106b. In some embodiments, the conductive material <NUM> surrounds substantially all of the interventional element <NUM>. In some embodiments, various sections of the interventional element <NUM> can be coated with the conductive material <NUM> and/or the insulating material <NUM> as shown in <FIG> or as shown in <FIG>.

The conductive material <NUM> can increase the electrical conductivity of the interventional element <NUM>. The conductive material <NUM> can include a material that has a higher electrical conductivity than the material used to form the body of the interventional element <NUM>. For example, the conductive material <NUM> can be a gold coating while the interventional element body can be formed from Nitinol. By coupling a higher electrically conductive material to the body of the interventional element <NUM>, an electric current can more easily pass through the interventional element <NUM> via the conductive material <NUM>, which thus, increases the electrical conductivity of the interventional element <NUM>. In some embodiments, the insulative material <NUM> can electrically isolate one or more portions of the interventional element. For example, the insulated material <NUM> can electrically isolate the attachment portion 106a of the interventional element <NUM>. By electrically isolating portions of the interventional element <NUM>, the insulating material <NUM> can be used to prevent electrical shortages between the interventional element <NUM> and the second conductor <NUM>. Additionally, the electrically isolating portions of the interventional element <NUM> with insulating material <NUM> can encourage current to flow to the distal portions of the interventional element <NUM>.

In some embodiments, the conductive material <NUM> is disposed in a thin layer on the outer surface of the interventional element <NUM>. For example, the conductive material <NUM> can have a thickness between about <NUM> microns to about <NUM> microns. Having a thickness within this range allows for the conductive material <NUM> to distribute current through the interventional element <NUM> without mechanically impacting the interventional element <NUM>. In some embodiments, the conductive material <NUM> can be formed from any suitable electrically conductive material. For example, the conductive material <NUM> can be formed from gold, silver, copper, platinum, palladium, iridium, ruthenium, rhodium, or corresponding alloys and combinations. In various embodiments, the conductive material <NUM> is formed from a metallic material. Additionally or alternatively, the conductive material <NUM> is formed from a noble metal. In some embodiments, the conductive material <NUM> is coupled to the interventional element <NUM> by coating, plating, surface-treating, or through vapor deposition.

<FIG> illustrates a side schematic view of a portion of the treatment device <NUM>. <FIG> illustrate cross-sectional views of the second conductor <NUM> along the lines 3B and 3C of <FIG>, respectively, with portions of the treatment <NUM> device hidden for clarity. As illustrated in <FIG>, the interventional element <NUM> is coupled to, and extends distally from, the first conductor <NUM>. The second conductor <NUM> can extend through the lumen of the first conductor <NUM> and beyond a distal end of the first conductor <NUM> such that a distal portion of the second conductor <NUM> extends through an interior region of the interventional element <NUM>. In some embodiments, the second conductor <NUM> can define a distal tip <NUM> at the distal portion <NUM> of the second conductor. As noted previously, an insulative material <NUM> can surround second conductor <NUM> along at least a portion of its length. At one or more positions along a distal region of the second conductor <NUM>, the second conductor <NUM> can include one or more uninsulated portions. In some embodiments, a conductive material <NUM> can couple to the one or more uninsulated portions. As illustrated in <FIG>, the conductive material <NUM> can be disposed over an outer surface of the second conductor <NUM> such that the conductive material <NUM> surrounds the second conductor <NUM> along at least a part of the length of the second conductor <NUM>. In some embodiments, the conductive material <NUM> couples to the second conductor <NUM> only at the uninsulated portions of the second conductor <NUM>. Additionally or alternatively, the conductive material <NUM> couples to the second conductor <NUM> along substantially the entire length of the second conductor <NUM>. In various embodiments, the conductive material <NUM> can be positioned radially adjacent to or distal of the interventional element. In some embodiments, the conductive material <NUM> can be radially disposed between the insulative material <NUM> and the second conductor <NUM>. In some embodiments, various sections of the second conductor <NUM> can be coated with the conductive material <NUM> and/or the insulating material <NUM> as shown in <FIG> or as shown in <FIG>.

The conductive material <NUM> can increase the electrical conductivity of the second conductor <NUM>. The conductive material <NUM> can comprise a material that has a higher electrical conductivity than the material used to form the body of the second conductor <NUM>. For example, the conductive material <NUM> can be a gold coating while the body of the second conductor <NUM> can be formed from stainless steel. By coupling a higher electrically conductive material to the body of the second conductor <NUM>, an electric current can more easily pass through the second conductor <NUM> via the conductive material <NUM>, which thus, increases the electrical conductivity of the second conductor <NUM>. In some embodiments, the insulative material <NUM> can electrically isolate one or more portions of the interventional element. For example, the insulated material <NUM> can electrically isolate the portions of the second conductor <NUM> that are adjacent the attachment portion 106a of the interventional element <NUM>. By electrically isolating portions of second conductor <NUM>, the insulating material <NUM> can be used to prevent electrical shortages between the interventional element <NUM> and the second conductor <NUM>. Additionally, electrically isolating portions of the second conductor <NUM> with insulating material <NUM> can encourage current to flow to the desired portions of the interventional element <NUM> (e.g., more distal portions). For example, as illustrated in <FIG>, the insulating material <NUM> can electrically isolate portions of the second conductor <NUM> adjacent the interventional element <NUM> while the distal tip <NUM> of the second conductor remains uninsulated. In this arrangement, or otherwise, current will be encouraged to flow to the distal portions of the interventional element <NUM> to reach the uninsulated distal tip <NUM>, as the adjacent portions of the second conductor <NUM> are electrically insulated.

In some embodiments, the conductive material <NUM> is disposed in a thin layer on the outer surface of the second conductor <NUM>. For example, the conductive material <NUM> can have a thickness between about <NUM> microns to about <NUM> microns. Having a thickness within this range allows for the conductive material <NUM> to distribute current through the second conductor <NUM> without mechanically impacting the second conductor <NUM>. In some embodiments, the conductive material <NUM> can be formed from an electrically conductive material. For example, the conductive material <NUM> can be formed from gold, silver, copper, platinum, palladium, iridium, ruthenium, rhodium, or corresponding alloys and combinations. In various embodiments, the conductive material <NUM> is formed from a metallic material. Additionally or alternatively, the conductive material <NUM> is formed from a noble metal. In some embodiments, the conductive material <NUM> is substantially the same as the conductive material <NUM>. In various embodiments, the conductive material <NUM> is coupled to the second conductor <NUM> by coating, plating, surface-treating, or through vapor deposition.

In various embodiments, the conductive material <NUM> of the second conductor <NUM> can be disposed radially adjacent to or distal of interventional element <NUM>. For example, the conductive material <NUM> can be disposed distally of the connection <NUM> and be positioned radially inward of the interventional element <NUM>. In some embodiments, one or more conductive material <NUM> portions extend (or are positioned) distally of the distal end of the interventional element <NUM>. In various embodiments, the second conductor <NUM> and the conductive material <NUM> are disposed within the lumen of the interventional element <NUM>. In some embodiments, the conductive material <NUM> can be disposed proximate or radially adjacent to the spaces or cell openings <NUM> bounded by the struts of the body 106b of the interventional element <NUM>. In some embodiments, each portion of the second conductor <NUM> with the conductive material <NUM> is positioned radially adjacent to a cell opening <NUM> of the interventional element <NUM>, and/or each portion of the second conductor <NUM> that is radially adjacent to a strut (and/or other metallic component, such as a radiopaque marker) of the interventional element <NUM> is insulated.

As noted previously, the interventional element <NUM> can be in electrical communication with the first conductor <NUM>, such that current supplied to a proximal end of the first conductor <NUM> is carried through the first conductor <NUM> to the interventional element <NUM>. The second conductor <NUM> can be covered with an electrically insulative material <NUM> with one or more uninsulated portions along the distal region of the second conductor <NUM>. The uninsulated portions can expose the underlying conductive material <NUM>, allowing for second conductor <NUM> to be electrically coupled to the interventional element <NUM> at the distal end portion of the second conductor <NUM>. In operation, the current generator <NUM> can couple to the core assembly <NUM> at the proximal portion 104a of the treatment device <NUM> and send a current through the first conductor <NUM>. This current can flow through the first conductor <NUM> to the interventional element <NUM> via the conductive material <NUM>. At the interventional element <NUM>, the current can flow through the patient's surrounding media (e.g., blood, tissue, saline, thrombus, etc.) to the uninsulated portions of the second conductor <NUM> via the conductive material <NUM>, where the current can then flow through the second conductor <NUM> and return to the current generator <NUM>.

<FIG> illustrate several schematic side views of a portion of the treatment device <NUM> according to one or more embodiments of the present technology. As noted previously, in some embodiments, the second conductor <NUM> can include a distal tip <NUM>. The distal tip <NUM> can be formed at the distal portion <NUM> of the second conductor <NUM> and can be uninsulated.

The distal tip <NUM> can be formed in a variety of different shapes and sizes. For example, as illustrated in <FIG>, the distal tip <NUM> can form a "J" shape, where the distal tip <NUM> has a first portion that extends distally from the distal portion <NUM> of the second conductor <NUM>, a second portion that curves and extends laterally, and a third portion that extends proximally towards the distal portion <NUM>. In some embodiments, the distal tip <NUM> can be formed in a helical or spiral shape. For example, as illustrated in <FIG>, the distal tip <NUM> can be formed in a helical shape that extends distally from the distal portion <NUM> of the second conductor <NUM>. In various embodiments, the distal tip <NUM> can form a spherical or spheroid shape. For example, as illustrated in <FIG>, the distal tip forms a partially hollowed sphere at the distal portion <NUM>. Additionally or alternatively, the distal tip <NUM> can have an enlarged radial dimension compared to the second conductor <NUM>. The enlarged radial dimension increases the surface area of the distal tip <NUM> relative to the second conductor <NUM>. In some embodiments, the distal tip <NUM> can comprise a distal embolization protection element, for example a basket, mesh, or filter configured to capture any fragments that separate from the thrombus during engagement with the interventional element <NUM>. Although several examples herein refer to a distal tip, in various embodiments such a distal element (e.g., J-shaped wire, helical or spiral winding, spheroid shape, or other radially enlarged portion) at a position spaced proximally from a distal terminus of the second conductor <NUM>. For example, such a distal element may be coupled to the second conductor <NUM> at a position distal of the interventional element <NUM>, while the second conductor <NUM> may extend distally beyond such a distal element, such as in the form of a wire or other feature extending distally of the distal element.

The distal tip <NUM> can improve the surface charge density along the surface of the second conductor <NUM>. For example, the distal tip <NUM> can have structural features (e.g., curves, spiral shape, an expandable spheroid shape, etc.) that provide an enlarged surface area compared to a straight wire or rod. This enlarged surface area may allow for the charge density to distribute throughout the surface of the distal tip <NUM> more evenly. By distributing the charge density in this manner, the risk of hydrogen and chlorine gas bubbles forming along the surface of the second conductor <NUM> is reduced.

In some embodiments, the conductive material <NUM> can be coupled to the distal tip <NUM>. For example, the conductive material <NUM> can surround the distal tip <NUM> along at least a portion of the length of the distal tip <NUM>. In some embodiments, the surface area defined by the conductive material <NUM> coupled to the distal tip <NUM> is between about <NUM>% to about <NUM>% of the surface area defined by the conductive material <NUM> coupled to the interventional element <NUM>. Coupling the conductive material <NUM> to the distal tip <NUM> can increase the electrical conductivity of the distal tip <NUM>. The conductive material <NUM> can comprise a material that has a higher electrical conductivity than the material used to form the distal tip <NUM>. For example, the conductive material <NUM> can be formed from a gold coating while the distal tip <NUM> can be formed from stainless steel. By coupling a more electrically conductive material to the distal tip <NUM>, an electric current can more easily pass through the distal tip via the conductive material <NUM>, which thus, increases the electrical conductivity of the distal tip <NUM>.

In various embodiments, distal tip <NUM> can be configured to allow for the interventional element <NUM> to maintain a desirable electrical charge distribution. For example, positioning the distal tip <NUM> proximate the distal end portion of the second conductor <NUM> encourages the more current to flow through the distal portions of the interventional element <NUM> to reach the distal tip <NUM>, which in turn allows for the interventional element <NUM> to maintain a favorable electrical charge distribution (e.g., with sufficiently high charge density at the distal region of the interventional element, along the working length of the interventional element, or other suitable charge distribution).

An example method of delivering a current to the treatment device <NUM> will now be described. First, the treatment device <NUM> is positioned within a patient at the treatment site. Once the treatment device <NUM> is properly positioned, the user can expand the interventional element <NUM> so that the interventional element <NUM> engages with the thrombus. After the interventional element <NUM> engages with the thrombus, the user can couple the core assembly <NUM> to the current generator <NUM>. In some embodiments, the core assembly <NUM> is previously coupled to the current generator <NUM>. The user can interact with current generator to initiate the supply of an electrical signal to the first conductor <NUM>. The electrical signal can travel toward the treatment site through the first conductor <NUM> and to the interventional element <NUM> via the conductive material <NUM>. The electrical signal can return to the current generator <NUM> by flowing from the interventional element <NUM>, through the surrounding media (e.g., blood, tissue, thrombus, etc.) to the second conductor <NUM> via the conductive material <NUM> and through the second conductor <NUM> to the current generator <NUM>. In some embodiments, the electrical signal is an electrical current of between about <NUM>-<NUM> mA. The electrical signal can be unipolar (e.g., DC) or bipolar (e.g., AC). In various embodiments, the current or voltage level of the electrical signal can be constant, periodic, irregular, or any combination thereof. In some embodiments, the electrical signal is supplied for a duration of time between about <NUM> seconds to about <NUM> minutes. In some embodiments, the electrical signal is supplied for a duration of time of two minutes or less. After the electrical signal is delivered to the treatment device <NUM> for the proper duration, the user can interact with current generator to stop the supply of the electrical signal. The user can then proximally retract the treatment device <NUM>, including the thrombus, into a surrounding catheter, and then remove the entire assembly from the patient.

The descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise form disclosed above. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Although specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, while steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein may also be combined to provide further embodiments.

Claim 1:
A medical device (<NUM>) comprising:
a core assembly (<NUM>) configured to be advanced within a corporeal lumen, the core assembly comprising:
a first conductor (<NUM>) having a proximal end portion (116a) and a distal end portion (116b), the first conductor forming a lumen;
a second conductor (<NUM>) at least partially disposed within the lumen of the first conductor, the second conductor comprising a first conductive material and having a proximal end portion and a distal end portion extending distal to the distal end portion of the first conductor;
an insulative material (<NUM>) disposed over at least a portion of the second conductor, the insulative material defining one or more uninsulated portions of the second conductor; and
a second conductive material (<NUM>, <NUM>) surrounding the second conductor along at least part of the one or more uninsulated portions, the second conductive material having a higher electrical conductivity than the first conductive material;
an interventional element (<NUM>) coupled to the distal end portion of the first conductor, the interventional element being electrically coupled to the first conductor, the interventional element comprising a body (106b) formed of a third conductive material; and
a fourth conductive material disposed over at least a portion of the third conductive material of the interventional element, the fourth conductive material having a higher electrical conductivity than the third conductive material.