Electrosurgical device for puncturing tissue

Abstract

An electrosurgical device is disclosed for creating a channel through a region of tissue within a patient's body using radiofrequency (RF) energy. The electrosurgical device is configured to have an outer diameter that is smaller than conventional RF wires. The electrosurgical device further includes an elongated active electrode tip, which provides enhances visualization capabilities. The low-profile electrosurgical device is capable of traversing narrow blood vessels, such as those in the peripheral vasculature. An electrically insulative thermal shield is disposed between the active electrode tip and an insulated proximal region. A rigidity component and a reinforcement structure are disposed proximal to the thermal shield. The components being formed on a core wire having reduced diameter distal region.

Description

ELECTROSURGICAL DEVICE FOR PUNCTURING TISSUETECHNICAL FIELD

[0001] The disclosure relates to radio frequency (RF) wires for applying RF energy to create a channel through a region of tissue within a patient's body. More specifically, the disclosure relates to a low-profile RF wire capable of puncturing tissue and traversing blood vessels, including but not limited to the peripheral vasculature.BACKGROUND OF THE ART

[0002] A totally occluded blood vessel is one that is completely blocked. To treat this condition, blood flow must be restored to the affected area. To accomplish this, a physician can perform a balloon angioplasty procedure to restore blood flow through the vessel.

[0003] A balloon angioplasty involves a physician crossing the occlusion so that they can inflate a balloon to open the vessel. If the physician is unable to cross the occlusion with a needle, and radio frequency (RF) needle / puncture device may be used.

[0004] Radio frequency wires are well-known devices used by interventional radiologists to puncture through tissue and / or tough occlusions that mechanical wires cannot cross. A common size for an RF wire is one with an outer diameter of 0.035” (0.889 mm), for example the Baylis PowerWire®, disclosed in US 9,510,900, which is hereby incorporated by reference. This particular RF wire is typically used for vessels larger than 3 mm in diameter. i

[0005] US 9,510,900 discloses an electrosurgical apparatus for cutting through tissue including an electrically conductive elongate member comprising a core wire, electrically connected to an energy delivery component comprising an electrode tip, an insulation layer, an electrically insulative thermal shield, and a support structure defining a planar distal face for forming the electrode tip. The outer diameter dimensions of the electrosurgical apparatus described are substantially similar to an 0.035” (0.889 mm) wire. These 0.889 mm guidewires are relatively narrow and flexible, however they cannot be used in smaller, peripheral blood vessels, such as blood vessels located in the arms, legs, hands, and feet.

[0006] Smaller diameter guide wires, sometimes referred to as “microwires”, typically have outer diameters in the range of 0.014” (0.3556 mm) to 0.018” (0.4572 mm) and can be used in the peripheral vasculature. However, in some cases, microwires are not able to pass through tough occlusions because they are limited to mechanical energy, which is not strong enough to pass through certain types of occlusions. A device that combines radio frequency puncture with microwire dimensions could offer advantages.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order that the invention may be readily understood, embodiments of the invention are illustrated by way of examples in the accompanying drawings, in which:

[0008] FIGS. 1A-1 B are illustrations of an electrosurgical device in accordance with an embodiment of the present invention;

[0009] FIG. 2 is an illustration of an electrically conductive inner elongate member of the electrosurgical device in accordance with an embodiment of the present invention;

[0010] FIG. 3 is an illustration of a support structure used to form an energy deliver component in accordance with an embodiment of the present invention;

[0011] FIGS. 4A and 4B are illustrations showing the formation of the energy delivery component in accordance with an embodiment of the present invention;

[0012] FIGS. 4C and 4D are illustrations showing the formation of the energy delivery component in accordance with an alternative embodiment of the present invention;

[0013] FIG. 5 is an illustration of a thermal shield for use on the electrosurgical device in accordance with an embodiment of the present invention;

[0014] FIG. 6 is an illustration of a coil for use on the electrosurgical device in accordance with an embodiment of the present invention;

[0015] FIGS. 7A-7D are illustrations of insulation layers on the electrosurgical in accordance with various embodiments of the present invention;

[0016] FIGS. 8A-8D are illustrations of insulation layers on the electrosurgical in accordance with alternative embodiments of the present invention; and

[0017] FIG. 9 is an illustration of an electrosurgical device in accordance with an alternative embodiment of the present invention.

[0018] In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily toscale, emphasis instead being placed upon generally illustrating the various concepts discussed herein.DETAILED DESCRIPTION

[0019] In one broad aspect, embodiments of the present invention comprise an electrosurgical device for creating a channel through a region of tissue using energy, the electrosurgical device comprising: an electrically conductive elongate member; and an energy delivery component provided at a distal end of the electrosurgical device, the energy delivery component being electrically coupled to the electrically conductive elongate member, the energy delivery component having an outer diameter and a length; the length of the energy delivery component is greater than the outer diameter of the energy delivery component.

[0020] As a feature of this aspect, the length of the energy delivery component is between about 1.4 mm and about 2.5 mm and the outer diameter of the energy delivery component is between about 0.3 mm and about 0.4 mm.

[0021] As a feature of this aspect, the energy delivery component is radiopaque.

[0022] As a feature of this aspect, the electrically conductive elongate member defines a proximal segment, a distal segment, and a tapered segment disposed between the proximal and distal segments, and a diameter of the electrically conductive elongate member in the distal segment is smaller than a diameter of the electrically conductive elongate member in the proximal segment.

[0023] As a feature of this aspect, the diameter of the electrically conductive elongate member in the distal segment is between about 0.1016 mm and about 0.1524 mm, and the diameter of the electrically conductive elongate member in the proximal segment is between about 0.2032 mm and about 0.2794 mm.

[0024] As a feature of this aspect, a length of the tapered segment is between about 5 mm and about 7 mm and a length of the distal segment is between about 23 mm and 27 mm.

[0025] As a feature of this aspect, the electrosurgical device further comprises a rigidity component located about at least a portion of the distal segment.

[0026] As a feature of this aspect, the electrosurgical device further comprises a reinforcement structure located proximal of the rigidity component, the reinforcement structure surrounding the tapered segment.

[0027] As a feature of this aspect, the electrically conductive elongate member defines a proximal segment, a distal segment, and an intermediate segment located between the proximal and distal segments, a diameter of the electrically conductive elongate member in the distal segment is smaller than a diameter of the electrically conductive elongate member in the intermediate segment, and a diameter of the electrically conductive elongate member in the proximal segment is greater than the diameter of the electrically conductive elongate member in the intermediate segment.

[0028] As a feature of this aspect, the electrically conductive elongate member defines a first tapered region and a second tapered region, the first tapered region located between the proximal segment and the intermediate segment, and the second tapered region located between the intermediate segment and the distal segment.

[0029] As a feature of this aspect, the electrosurgical device further comprises an electrically insulative thermal shield disposed between the energy delivery component and an electrically insulated region.

[0030] As a feature of this aspect, the longitudinal length of the energy delivery component is greater than a longitudinal length of the electrically insulative thermal shield.

[0031] As a feature of this aspect, the longitudinal length of the electrically insulative thermal shield is between about 1.9 mm and about 2.1 mm.

[0032] As a feature of this aspect, the electrically conductive elongate member comprises stainless steel.

[0033] As a feature of this aspect, the rigidity component comprises a coil.

[0034] As a feature of this aspect, the coil is radiopaque.

[0035] As a feature of this aspect, the reinforcement structure comprises a hypotube.

[0036] As a feature of this aspect, the electrically insulative thermal shield comprises platinum.

[0037] As a feature of this aspect, the energy delivery component comprises a tubular support structure and a distal tip, and a distal portion of the electrically conductive elongate member is positioned through the tubular support structure, the tubular support structure defining a substantially planar distal face that is substantially perpendicular to a device longitudinal axis for enabling the distal tip to be formed integrally with a distal end of the electrically conductive elongate member.

[0038] As a feature of this aspect, the energy delivery component comprises a tubular support structure and a distal tip, and a distal portion of the electrically conductive elongate member is positioned within the tubular support structure and the distal tip is formed integrally with a distal end of the electrically conductive elongate member.

[0039] As a feature of this aspect, a diameter of distal tip is greater than a diameter of the support structure.

[0040] As a feature of this aspect, the electrosurgical device further comprises an insulation layer covering a portion of the proximal segment and extending to at least a proximal end of the electrically insulative thermal shield.

[0041] As a feature of this aspect, the electrosurgical device further comprises an adhesive located between the electrically insulation thermal shield and the insulation layer.

[0042] As a feature of this aspect, the insulation layer surrounds a proximal portion of the electrically insulated thermal shield.

[0043] As a feature of this aspect, the electrically insulated thermal shield defines a reduced diameter proximal portion.

[0044] As a feature of this aspect, the reduced diameter proximal portion defines a taper.

[0045] As a feature of this aspect, a diameter of the electrically insulated thermal shield is smaller than the outer diameter of the energy delivery component.

[0046] As a feature of this aspect, the electrosurgical device further comprises a plurality of radiopaque support structures.

[0047] As a feature of this aspect, the electrosurgical device further comprises: a first insulation layer; a second insulation layer; an electrically exposed region for delivering energy to the region of tissue; and an electrically insulated region, the electrically insulated region comprising a proximal insulated portion and a distal insulated portion; the first insulation layer surrounds the proximal insulated portion and the second insulation layer surrounds the firstinsulation layer and extends beyond the first insulation layer to cover the distal insulated portion.

[0048] As a feature of this aspect, the electrosurgical device of claim 4 further comprises: a first insulation layer; a second insulation layer; the first insulation layer surrounds the proximal segment and the second insulation layer surrounds the first insulation layer and extends beyond the first insulation layer to cover the distal segment.

[0049] In another broad aspect, embodiments of the present invention comprise a low-profile electrosurgical device for creating a channel through a region of tissue using energy, the electrosurgical device comprising: an electrically conductive elongate member; and an energy delivery component provided at a distal end of the electrosurgical device, the energy delivery component being electrically coupled to the electrically conductive elongate member, the energy delivery component having an outer diameter and a length; the length of the energy delivery component is greater than the outer diameter of the energy delivery component.

[0050] With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of certain embodiments of the present invention only. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0051] As mentioned above, 0.889 mm RF wires cannot be used in blood vessels of a particular size, such as in the peripheral vasculature. Microwires such as 0.3556 mmm wires may traverse the peripheral vasculature, but traditional, mechanical wires lack the ability to cut through tissue using RF energy.

[0052] Merely reducing the diameter of known components will not lead to a functioning wire, as will be described here. For example, the PowerWire® disclosed above discloses a 0.254 mm long tantalum puck, with a dome welded at the distal end to form at energy delivery component the distal tip. Proximal to the puck is a thermal shield, and proximal to the thermal shield is a marker band. Insulation layers extend from the proximal end up to the thermal shield, and cover part of the thermal shield. This RF wire was designed to have a point of energy highly focused at the distal most tip.

[0053] US 9,510,900 further discloses a distal electrode tip that is shorter than it is wide, as well as a tip that is much shorter than the thermal shield. For example, the outer diameter of the tantalum is 0.0821 mm. The length of the weld at the distal tip is approximately 0.2 mm, and the total tip length of weld plus puck is approximately 0.454 mm. A specific example is given of the electrode tip having an outer diameter between about 0.6858 mm (0.027”) and 0.8128 mm (0.032”), and longitudinal length of 0.015 mm to 0.20 mm. The thermal shield disclosed has a length of about 2 - 3 mm, and, in a specific example, a length of 2.54 mm.

[0054] As discussed further hereinbelow, for a given RF generator output, the active tip should have a surface area above a certain threshold in order to effectively cut through tissue. Reducing the diameters of the components while maintaining the same longitudinal lengths would reduce the surface area of the active tip and result in inefficient or ineffective cutting. More specifically, reductions to the tip surface area below a given amount increase the impedanceof the AC circuit formed by the generator, RF wire and grounding pad such that the power required for effective cutting may be too high for the generator to provide, resulting in decreased cutting efficacy. Thus, simply reducing the overall diameter may result in a non-functional, or at least inefficient, energy delivery system.

[0055] The inventors have devised a novel solution to create an RF wire with microwire-type dimensions, characteristics, and capabilities that is usable to effectively cut tissue using energy delivery. More specifically, they have developed a radio frequency wire having a lower profile, with an elongated active electrical tip. The elongated tip provides surface area to conduct the RF energy. This low-profile wire, or RF microwire, can access the peripheral vasculature, and apply RF energy to pass through tissue such as occlusions. The slender, elongated active electrode tip provides enough energy to pass through an occlusion, similar to an 0.889 mm wire.

[0056] For clarity, the term low-profile means a diameter similar to that of microwires, as would be known to those skilled in the art and having outer diameters in the range 0.014” (0.3556 mm) to 0.018” (0.4572 mm). Further, low- profile means have flexibility / stiffness characteristics similar to microwires, capable of maneuvering through vasculature that a corresponding 0.035” (0.889 mm) wire could not.

[0057] A 0.014” (0.3556 mm) diameter wire offers other advantages over an 0.035” (0.889 mm) wire in larger vessels as well. In some cases, a low-profile wire can offer increased flexibility, and can be capable of traversing more difficult, or more tortuous anatomy that requires sharp turns.

[0058] Referring to FIGS. 1A and 1 B, in accordance with one embodiment of the present invention, an electrosurgical device 100 is provided having an inner elongate member 102 extending from a distal end 101 to a proximal end 103.Inner elongate member 102 is an electrical conductor and is electrically coupled to an energy delivery component or active electrode tip 104 at distal end 101. Electrosurgical device 100 additionally comprises an electrically insulative thermal shield 106, rigidity component 108, reinforcement structure 148, and electrical insulation layer 110. FIG. 1 B shows the features of electrosurgical device 100 with the insulation layer 110 removed for clarity. “Electrically insulative thermal shield 106” may be referred to as “thermal shield 106”.

[0059] Active electrode tip 104 includes support structure 112 and distal tip 114, described in more detail herein. Thermal shield 106 separates the active electrode tip 104 from insulation layer 110. Electrosurgical device 100 further comprises an electrically exposed region 120 and an electrically insulated region 122. Electrosurgical device 100 may also be referred to as “RF wire” or “RF guidewire”.

[0060] In one embodiment, active electrode tip 104 is integrally formed with the inner elongate member 102 and is located at distal end 101 of electrosurgical device 100, thermal shield 106 is proximal to the active electrode tip 104, rigidity component 108 is proximal to thermal shield 106, and reinforcement structure 148 is proximal to rigidity component 108. Electrical insulation layer 110 surrounds rigidity component 108, reinforcement structure 148, and a proximal portion of inner elongate member 102. In some embodiments, electrical insulation layer 110 surrounds a portion of thermal shield 106, as will be described herein.

[0061] In one embodiment, rigidity component 108 comprises a coil 108, for example a metal coil. Coil 108 adds additional rigidity to a portion of the inner elongate member 102 with a smaller diameter to the rest of the elongate member

[0062] In one embodiment, reinforcement structural 48 comprises a hypotube 148, for example a metal hypotube. In other embodiments, reinforcement structure 148 comprises a different material. Hypotube 148 is a rigid structure and prevents gaps from forming between other components during the manufacturing process. In some embodiments, electrosurgical device 100 does not have a reinforcement structure 148.

[0063] In one embodiment, electrosurgical device 100 has a substantially uniform outer diameter, for example about between about 0.0115” (0.2921 mm) and 0.014” (0.3556 mm) along its length. In one embodiment, the outer diameter of electrosurgical device 100 that is covered by insulation layer 110 in the proximal region is approximately 0.014” (0.3556 mm), the outer diameter of the thermal shield 106 is 0.0115” (0.2921 mm), and the outer diameter of the support structure 112 is 0.0125” (0.3175 mm). In one example, the device has sufficient flexibility and dimensions to conform to the peripheral vasculature of a patient, for example, in a narrow blood vessel such as a blood vessel below the knee. The electrosurgical device 100 further has sufficient rigidity to allow pushability through tissue.Tapered Inner Member

[0064] Referring to FIG. 2, in one embodiment, inner elongate member 102 comprises a core wire 118 and has a varying diameter along its length. In one example, core wire 118 comprises stainless steel. Alternatively, any other suitable material may be used for core wire 118, for example nitinol. Core wire 118 extends the entire length of the device and connects the power source at the proximal end 103 to the active electrode tip 104 at the distal end 101. Core wire 118 is electrically conductive and provides the desired mechanical properties required for vascular procedures such as stiffness and torque-ability so aphysician can navigate through the patient’s vasculature and through an occlusion.

[0065] In one embodiment the distal region of the core wire 118 has a smaller diameter than the proximal portion to allow room for the components to be added. In one embodiment, inner elongate member 102 defines a taper between a larger diameter proximal region and a smaller diameter distal region so that support structure 112, thermal shield 106, hypotube 148, and coil 108 can be placed on inner elongate member 102 in the distal region. The reduced diameter of the distal portion of the core wire 118 also provides reduced flexural rigidity.

[0066] In one embodiment, inner elongate member 102 has a longitudinal length L1 and defines proximal region 102a, tapered region 102b, and distal region 102c. In other embodiments, inner elongate member 102 does not have a tapered region 102b, in other words, there is a discrete change in outer diameter, such as a step. Tapered region 102b has a longitudinal length L3 and distal region 102c has a length L4. In some examples, L1 is between about 180 and about 310 cm, L3 is between about 4 and about 8 mm and L4 is between about 23 mm and about 27 mm.

[0067] The outer diameter D1 of the elongate member 102 in the proximal region 102a is greater than the outer diameter D2 of the elongate member 102 in the distal region 102c. Tapered region 102b has a varying diameter. In one example, D1 is between about 0.2032 mm (0.008”) and about 0.2794 mm (0.011”), for example about 0.254 mm (0.01”), and D2 is between about 0.1016 mm (0.004”) and 0.1524 mm (0.006”), for example about 0.127 mm (0.005”).

[0068] A proximal end 103 of the inner elongate member 102 is configured to be coupled to an energy source, such as a generator (not shown), and a proximal portion of the inner elongate member 102 having a longitudinal lengthL2 is exposed / uninsulated, i.e., does not have the same insulation layers as the rest of the device. In one example, L2 is between about 4 mm and about 14 mm.Elongated Active Tip

[0069] To pass through an occlusion, electrosurgical device 100 comprises an active tip that applies RF energy to the occlusion and vaporizes the occlusion material. The active tip should have a relatively small surface area to focus the RF energy and heat the tissue rapidly. For a 0.035” (0.889 mm) diameter RF wire, to direct the RF energy forwards into the occlusion, the tip should have a short and wide profile compared to a long and narrow one (i.e., the tip diameter should be maximized, and the length should be minimized).

[0070] Although a smaller tip focusses energy and vaporizes (“cuts”) tissue more efficiently, there is a point at which further reductions to the tip surface area increase the impedance of the AC circuit such that power delivered from the generator is reduced, resulting in decreased cutting efficacy. Therefore, the cutting efficacy is maximized when the surface area is above a threshold.

[0071] One type of generator for use with electrosurgical device 100 may deliver 468 kHz sinusoidal RF energy, with a maximum output power of 50 W. In use, for example with such a generator, if the impedance of the circuit remains below approximately 1800 Ohms, the generator can apply 50 Watts of power to the electrosurgical device 100. If the impedance of the circuit is above 1800 Ohms, the generator applies less power.

[0072] In order to achieve the most efficient use for cutting through tissue, when used with the generator described herein, the tip surface area should be within a certain range so that maximum power is applied from the generator and cutting time is minimized. In one embodiment, the upper limit of the surface areausable to achieve 1800 Q impedance was found to be between about 2.2 mm2. Above this range, the surface area of the active tip may be too large to concentrate the RF energy and direct it to cut tissue effectively.

[0073] To achieve the required surface area under about 2.2 mm2with a 0.3175 mm (0.0125”) diameter, the active tip in this embodiment has a length of between about 1 .6 mm to about 1 .8 mm.

[0074] As shown in FIGS. 1A and 1 B, active electrode tip 104 is located at the distal end 101 of electrosurgical device 100 and is configured to deliver energy to a region of tissue within a patient. In one embodiment, active electrode tip 104 comprises support structure 112 and a distal tip 114.

[0075] In one embodiment, support structure 112 is an electrically conductive tubular member comprising a radiopaque material, for example platinum. In other examples, support structure 112 may comprise materials such as iridium, gold, silver, stainless steel, tantalum, tungsten, or their alloys. In one example, support structure 112 comprises 90% platinum and 10% iridium (90 / 10 Ptlr). In one specific example, support structure 112 is a radiopaque marker band.

[0076] Referring to FIG. 3, in one embodiment, support structure 112 is a tubular member defining a channel or lumen, such that the inner elongate member 102 can pass through the channel. In other words, a tubular member through which core wire 118 can be threaded. Support structure has a distal face 116 and a proximal face (not shown). Support structure has a length L5, an outer diameter D4 and inner diameter D5. In one example, L5 is between about 1.6 mm and 1.8mm, D4 is between about 0.3302 mm (0.012”) and 0.3556 mm (0.013”), and D5 is between about 0.127 mm (0.005”) and 0.1778 mm (0.007”).

[0077] Referring to FIGS. 4A and 4B, the active electrode tip 104 may be formed by inserting the core wire 118 through support structure 112, such that a distal portion of the elongate member 102 extends through the distal end ofsupport structure 112. In one embodiment, the distal end 101 of elongate member 102 is laser welded to form a distal tip 114. Support structure 112 defines a distal face 116 that is substantially perpendicular to the support structure longitudinal axis. Distal face 116 provides a surface for the distal tip 114 to be formed.

[0078] FIG. 4A shows the inner elongate member 102 extending distally through support structure 112 and past distal face 116, before laser welding. FIG. 4B shows the distal tip 114 after laser welding, the active tip being formed on distal face 116. In other words, core wire 118 is welded to form the distal tip 114 on the support structure 112, such that core wire 118, distal tip 114 and support structure 112 are integrally formed.

[0079] With reference to FIG. 4C, in another embodiment, core wire 118 does not extend beyond distal face 116 prior to welding. In such an embodiment, support structure 112 distal end can be formed into a rounded distal tip, for example by welding. FIG. 4C shows the core wire 118 extending partially into support structure 112 prior to forming the distal tip. In such an embodiment, the distal tip (dome) is the same material as the support structure 112.

[0080] In some embodiments, support structure 112 is smaller than .014” in diameter, and the distal tip 114 may be formed with a wider diameter than support structure 112, for example a rounded shape or “mushroom” shape, as shown in FIG. 4D. Such an embodiment may create slightly larger holes in tissue than the embodiment in FIG. 4B.

[0081] In one embodiment, support structure 112 comprises a radiopaque material, for example platinum, thus, electrosurgical device 100 has an elongated radiopaque tip, which may offer improvements over the existing RF wires as the tip is more visible under visualization modalities.

[0082] Distal tip 114 may have an atraumatic shape, for example a rounded shape or half-spherical as shown in FIG. 4B. In other embodiments, distal tip 114 may have other shaped tips that are substantially atraumatic, for example spherical or ellipsoid. In one embodiment, distal tip 114 is a generally half- spherical shape, has a longitudinal length L6 and diameter D5. Thus, the longitudinal length L7 of the active electrode tip 104 is the sum of L5 and L6. In one example, D5 is between about 0.3302 mm (0.012”) and about 0.3556 mm (0.014”) and L7 is between about 1.6 mm and about 2.5 mm, such that the longitudinal length of the active electrode tip 104 is greater than its diameter.

[0083] The active electrode tip 104 is thus significantly longer than it is wide. In other words, it is an elongated energy delivery component. For clarity, the term ‘elongate’ or ‘elongated’ means something with a length greater than its widest point. For example, for a cylindrical or tubular member: the length is greater than the diameter. In one example, the surface area of the active electrode tip 104 is between about 1.6 mm2and 2.1 mm2. The active electrode tip 104 surface area should be above a minimum threshold to be compatible with a power source (so impedance is not too high) but cannot be too large because of the need to focus energy.

[0084] The need to create an elongated energy delivery component for this application is an unexpected result because in other radio frequency wires, a focused point of energy delivery at the very distal-most point, (distal tip) is typically the goal. In the present invention, the entire energy delivery component radiates energy in all directions, yet still focuses enough energy to cut tissue.Thermal Shield

[0085] In one embodiment, electrosurgical device 100 comprises an electrically insulative thermal shield 106 (or “heat shield”) affixed to the innerelongate member 102 and positioned proximal of the active electrode tip 104 and distal to insulation layer 110. Thermal shield 106 isolates and absorbs heat generated by the active electrode tip 104 and prevents damage to insulation layer 110. In one embodiment, thermal shield 106 comprises sapphire material. In other embodiments, thermal shield 106 may comprise alumina, silicon nitride, silicone, or another ceramic material.

[0086] Referring to FIG. 5, in one embodiment, thermal shield 106 has a tubular shape with rounded edges, with a longitudinal length L8, an inner diameter D6, outer diameter D7, and rounded edges having radius R1. D6 may be slightly larger than D2, such that thermal shield 106 may be slid over the distal region 102c of core wire 118.

[0087] In one embodiment, L8 is between about 1.0 mm and about 3.0 mm, for example 2.0 mm, D6 is between about 0.127 mm (0.005”) and about 0.2032 mm (0.008”), for example about 0.1524 mm (0.006”), and D7 is between about 0.2794 mm (0.011”) and about 0.3556 mm (0.014”), for example about 0.2921 mm (0.0115”). In some embodiments, thermal shield 106 is longer than active electrode tip 104, in other words, L8 is greater than L7. In an alternative embodiment, thermal shield 106 is shorter than active electrode tip 104, in other words, L8 is less than L7.

[0088] In one embodiment, the thermal shield 106 has a uniform inner diameter D6 and a uniform outer diameter D7. In other embodiments, the thermal shield has a varying outer diameter, for example a tapered proximal segment, or a reduced outer diameter segment in the proximal region, to allow for a portion of insulation layer 110 to cover a portion of the thermal shield 106 proximal region, and to allow for a smooth transition from the electrically insulated region 122 to the thermal shield 106. In another embodiment, described herein, thermal shield 106 has an outer diameter D7 between about 0.2032 mm (0.008”) and about0.254mm (0.010”), for example about 0.2286 mm (0.009”), to allow for insulation layer 110 to overlap a portion of it.Radiopaque Coil

[0089] In one embodiment, a distal region of low-profile RF wire has a slender diameter (approximately 0.127 mm (0.005”)) so that components can be added. This slender core wire 118 makes the electrosurgical device 100 more flexible wire than typical RF wires, however this also reduces rigidity and / or pushability properties. To increase the stiffness and to prevent the core wire 118 from kinking in the distal region 102c, in one embodiment, electrosurgical device 100 comprises rigidity component 108, for example coil 108, positioned about distal region 102c, such that coil 108 covers or wraps around core wire 118. In one embodiment, coil 108 comprises a radiopaque material, for example tungsten, or platinum tungsten. In another example, coil 108 comprises platinum iridium. In some embodiments, core wire 118 is not radiopaque. In other embodiments, rigidity component 108 has another structure, for example flexible element that adds additional rigidity, for example an extra segment of insulation.

[0090] With reference to FIG. 6, in one embodiment, coil 108 is made from a wire having diameter D8 and is configured to wind around a portion of core wire 118 to form a coiled shape with a longitudinal length L9, inner diameter D9, and outer diameter D10. Inner diameter D9 defined by coil 108 is substantially the same as the other diameter D2 of the core wire 118 in the distal region 102c. Wire diameter may also be referred to as “wire thickness”. In one example, wire thickness D8 is between about 0.0254 mm (0.001”) and 0.0508 mm (0.002”), for example about 0.04191 mm (0.00165”).

[0091] Coil 108 is configured to surround or “wrap around” the inner elongate member 102 in distal region 102c. In one example, outer diameter D10 isbetween about 0.2032 mm (0.008”) and 0.254 mm (0.010”), for example about 0.2413 mm (0.0095”) and inner diameter D9 is between about 0.127 mm (0.005”) and 0.1778 mm (0.007”), for example about 0.1524 mm (0.006”), to accommodate for the reduced outer diameter D2 of the inner elongate member 102 in the distal region 102c, which is approximately 0.127 mm (0.005”). In one example, L9 is between about 17 mm and 19 mm, for example about 18 mm.

[0092] In some embodiments, when coil 108 is wrapped around the distal region 102c, the diameter of the wrapped coil 108 plus inner elongate member 102 may be approximately equal to the diameter D1 of the proximal region 102a, thereby creating a more uniform outer diameter along electrosurgical device 100. In some embodiments, coil 108 covers a portion of the tapered region 102b.

[0093] In embodiments having reinforcement structure 148, for example hypotube 148, hypotube 148 surrounds a portion of the core wire 118 proximal to coil 108 to prevent other components from shifting and prevent gaps from forming. In one example, hypotube 148 is a tubular component positioned over a proximal portion of coil 108, near the tapered region 102b. In some embodiments, hypotube 148 is affixed to coil 108 and / or a portion of elongate member 102. In other embodiments, one or more components are not affixed to elongate member 102, and are secured in place via the application of insulation layer 110, described herein.

[0094] In one embodiment, hypotube 148 is a tubular structure similar to support structure 112 described herein, but not shown in detail in the figures. In one embodiment, hypotube has a length L20, an inner diameter D22 and an outer diameter D24 (not shown). In one specific example, L20 is between about 0.30 mm and 0.70 mm, D22 is between about 0.0055” and 0.0073”, and D24 is between about 0.0088” and 0.0108”. In some embodiments, hypotube 148 comprises a metal hypotube.

[0095] During formation of the active electrode tip 104 described herein, hypotube 148 and coil 108 are placed on the inner elongate member 102 up to approximately the distal end of the tapered region 102b, or alternatively at the proximal end of the distal region 102c. Next the thermal shield 106 is placed on the inner elongate member 102 distal to coil 108, and then support structure 112 is placed on the inner elongate member distal to the thermal shield 106, as shown in FIG. 1 B. In one embodiment, hypotube 148 surrounds a portion of the tapered region 102b. In other embodiments, hypotube 148 is placed on the tapered region 102b, and length of 102b is longer than hypotube 128, and a portion of coil 108 also surrounds a portion of tapered region 102b.Insulation Layer(s)

[0096] In one embodiment, electrosurgical device 100 comprises insulation layer 110 disposed on a proximal portion of the elongate member 102, such that the insulation layer 110 substantially surrounds the inner elongate member 102 to minimize energy leakage. As would be apparent to one skilled in the art, the terms ‘surrounds’ or ‘covers’ as used herein can indicate, for example, that the insulation is applied directly to the elongate member 102 or, as another example, that the insulation is applied to some intermediate layer located on the elongate member. “Surrounds” may also mean “disposed about” or “disposed on”.

[0097] Insulation layer 110 helps to electrically insulate a portion of the electrosurgical device 100. This may help protect the patient and the physician from exposure to electrical current during use of electrosurgical device 100. In one embodiment, electrically insulated region 122 extends from a proximal region near the proximal end 103 and overlaps a portion of thermal shield 106, as shown in FIG. 1A. In another embodiment, the electrically insulated region 122 extends substantially from a proximal region of the electrosurgical device 100 tothe proximal end of the thermal shield 106. The electrosurgical device 100 proximal end 103 has an uninsulated region adapted to be connected to an energy source, for example a generator. In other words, the electrically insulated region 122 is substantially covered by insulation layer 110 except for a portion of the proximal region.

[0098] Referring to FIG. 7A, in one embodiment, electrosurgical device 100 has an electrically exposed region 120 and an electrically insulated region 122 comprising one or more insulation layers 110. Insulation layer 110 extends from a proximal region to at least the proximal end of thermal shield 106. In some embodiments, insulation layer 110 covers a proximal portion of thermal shield 106. In some embodiments, the outer diameter of thermal shield 106 is less than the outer diameter of the active electrode tip 104 / support structure 112. Insulation layer 110 is disposed around the elongate member 102, surrounding coil 108 and hypotube 148.

[0099] A variety of materials may be used for insulation layer 110, including but not limited to polymer or ceramic. Insulation layer 110 may be provided using a heat shrink process or a melt processing method. Alternatively, any other suitable method may be used. Insulation layer 110 may be a polyimide, polyamide-imide, and polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), Polyethylene terephthalate (PET) polyurethane, nylon, polypropylene, silicone, polyether block amide (Pebax), and High-Density Polyethylene (HDPE), polyolefin (RNF), and fluorinated ethylene propylene (FEP). In some embodiments, insulation layer 110 comprises a lubricious outer coating and / or a hydrophilic coating.

[0100] In one embodiment, with the insulation layer 110, the total outer diameter of electrosurgical device 100 is approximately 0.3556 mm (0.014”). Insulation layer 110 thickness may vary along various portions of electrosurgical device 100, for example, a thicker layer of insulation in tapered region 102b, butthe overall electrosurgical device 100 outer diameter is approximately 0.3556 mm (0.014”), along its entire length.

[0101] In an alternative embodiment, shown in FIG. 7B, insulation extends up the distal end of coil 108 / proximal end of thermal shield 106, and electrosurgical device 100 comprises an adhesive 146 between the distal end of the coil 108 and the proximal end of thermal shield 106. In one example, adhesive 146 comprises epoxy. Adhesive 146 may be used at other locations to secure other components together, for example to secure the thermal shield 106 to the active electrode tip 104 and / or core wire 118.

[0102] In embodiments where insulation layer 110 overlaps a proximal portion of thermal shield 106, the overlapped portion forms a bulge. In order to maintain a low-profile, a smooth transition is required from the insulation layer 110 to the thermal shield 106 while maintaining an overall outer diameter of 0.3556 mm (0.014”), in other words, without producing a bulge greater than 0.3556 mm (0.014”), and without allowing energy leakage.

[0103] In some embodiments, electrosurgical device 100 comprises a reduced diameter thermal shield 106, for example the diameter of thermal shield 106 is smaller than the diameter of support structure 112. In one specific embodiment, thermal shield 106 has an outer diameter of between about 0.2286 mm (0.009”) and about 0.3048 mm (0.012”). The reduced outer diameter of thermal shield 106 allows a portion of insulation layer 110 to extend over and cover a proximal portion of thermal shield 106. In one embodiment, the length of thermal shield is between about 1 mm and about 3 mm.

[0104] Referring to FIG. 7C, in another embodiment, thermal shield 106’ defines a smaller diameter at its proximal end and a greater diameter at its distal end. This allows insulation layer 110 to form around the proximal portion ofthermal shield 106. In one embodiment, thermal shield 106 defines a taper at the proximal region, and insulation layer 110 extends over a portion of the taper.

[0105] Referring to FIG. 7D, in another embodiment, thermal shield 106” defines a discrete diameter change, or a “step-down” change, with a first outer diameter in the distal end, and a second, smaller outer diameter at the proximal end. In such an embodiment, insulation layer 110 forms around the proximal portion. This allows for a smooth transition between the thermal shield 106 and the insulation layer 110 and may also allow for a secure junction to be formed between the two materials.

[0106] This helps ensure that the core wire 118 is not exposed at the junction. Furthermore, the smooth outer profile at the junction may prevent tissue from getting caught and snagging at the junction which may allow electrosurgical device 100 to traverse through the occlusion relatively easily.Other Insulation Configurations

[0107] Referring to FIGS. 8A to 8D, in one embodiment, electrically insulated region 122 comprises proximal insulated portion 124 and a distal insulated portion 126. Distal insulated portion 126 extends from the proximal end of tapered region 102b to the thermal shield 106. In one embodiment insulation layer 110 comprises a first insulation layer 110a, and a second insulation layer 110b. (In some examples, the terms “portion” and “region” may be used interchangeably.)

[0108] In one embodiment, first insulation layer 110a is disposed upon the core wire 118. First insulation layer 110a may be applied to core wire 118 in a spray coating, dip coating, plasma coating process, or an extrusion / reflow process. As a method of manufacture, first insulation layer 110a may be appliedto the length of core wire 118, and then inner elongate member 102 may be ground down to form tapered region 102b and distal region 102c. During the grinding process, first insulation layer 110a is removed, exposing core wire 118 in the distal insulated portion 126. In other words, first insulation layer 110a surrounds only the proximal region 102a, in the proximal insulated portion 124. In other embodiments, first insulation layer 110a may surround both the proximal insulated portion 124 and the distal insulated portion 126. In some embodiments, first insulation layer 110a may be applied to the core wire 118 after the core wire 118 has been ground into the profiled shape.

[0109] In one embodiment, first insulation layer 110a comprises polytetrafluoroethylene (PTFE). In other embodiments, first insulation layer 110a may be ethylene-tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), perfluoroalkoxylethylene-tetrafluoroethylene (PFA), polyimide, parylene, parylene N, or Polyethylene terephthalate (PET).

[0110] Second insulation layer 110b may be disposed around the elongate member 102, including around first insulation layer 110a and surrounding coil 108. Second insulation layer 110b covers both proximal insulation portion 124 and distal insulated portion 126. In other words, it covers first insulation layer 110a and extends distally to cover the remainder of inner elongate member 102 up to the thermal shield 106. A variety of materials may be used for the second insulation layer 110b, including but not limited to polymer or ceramic.

[0111] Second insulation layer 110b may be provided using a heat shrink process or a melt processing method. Alternatively, any other suitable method may be used. Second insulation layer 110b may be a polyimide, polyamideimide, and polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), Polyethylene terephthalate (PET) polyurethane, nylon, polypropylene, silicone, polyether block amide (Pebax), and High-Density Polyethylene (HDPE), polyolefin (RNF), and fluorinated ethylene propylene (FEP). In someembodiments, insulation layer 110 comprises a lubricious outer coating. In other embodiments, electrosurgical device 100 and / or insulation layer 110 comprises a hydrophilic coating.

[0112] Once assembled, proximal insulated portion 124 includes a first insulation layer 110a and second insulation layer 110b, and distal insulated portion 126 includes only the second insulation layer 110b. First insulation layer 110a extends from a proximal region of the inner elongate member 102 up to the distal insulated portion 126 / tapered region 102b. Second insulation layer 110b extends from a proximal region of electrosurgical device 100 to the thermal shield 106. In other words, second insulation layer 110b extends beyond first insulation layer 110a in a distal direction along the electrosurgical device 100 longitudinal axis, as shown in FIG. 8A.

[0113] In one embodiment, with the first and second insulation layers are applied, the total outer diameter of electrosurgical device 100 is approximately 0.3556 mm (0.014”). Insulation layer thickness may vary along various portions of electrosurgical device 100, for example, in the proximal region 102a, where inner elongate member 102 outer diameter D1 is approximately 0.254 mm (0.010”), the thickness of insulation is approximately 0.1016 mm (0.004”). In the tapered region 102b and distal region 102c, insulation layer is thicker, so that overall, the electrosurgical device 100 outer diameter is approximately 0.3556 mm (0.014”), along its entire length.

[0114] With reference to FIG. 8B, in another embodiment, electrosurgical device 100B comprises a first insulation layer 110a that extends over proximal region 102a, tapered region 102b, and a portion of distal region 102c. Electrosurgical device 100A comprises electrically insulated region 122 that includes proximal insulated portion 124 and distal insulated portion 126. Proximal insulated portion 124 extends from the proximal region of the device up tothermal shield 106, in other words it includes proximal region 102a, tapered region 102b, and a portion of distal region 102c.

[0115] In this embodiment, proximal insulated portion 124 includes first insulation layer 110a and second insulation layer 110b, and distal insulated portion 126 includes only first insulation layer 110a, as shown in FIG. 8B.

[0116] With reference to FIG. 8C, in another embodiment, core wire 118 does not comprise a first insulation layer in the proximal region 102a. Electrosurgical device 100B comprises electrically insulated region 122 that includes three insulated portions: proximal insulated portion 125a, middle insulated portion 125b, and distal insulated portion 125c.

[0117] In one embodiment, proximal insulated portion 125a extends from a proximal region of the device up to tapered region 102b, in other words it covers proximal region 102a. Middle insulated portion 125b extends from tapered region 102b to a portion of distal region 102c, for example up to thermal shield 106. Distal insulated portion 125c covers a portion of distal region 102c and extends from the thermal shield 106 to a portion within support structure 112.

[0118] In such an embodiment, proximal insulated portion 125a comprises only the second insulation layer 110b. Middle insulated portion 125b comprises first insulation layer 110a and second insulation layer 110b. Distal insulated portion 125c comprises only first insulation layer 110a, as shown in FIG. 8C. In other words, elongate member 102 / core wire 118 comprises one layer of insulation in a proximal region, two layers of insulation in a middle region, and one layer of insulation in the distal region, where the layer in the proximal region is different from the layer in the distal region, and the middle region comprises both layers.

[0119] In one embodiment, first insulation layer 110a is disposed on the core wire 118 under the coil 108, the thermal shield 106, and a portion of the supportstructure 112, as shown in FIG. 8C. In another embodiment, distal insulated portion 125c covers only a portion of the core wire 118 under the thermal shield 106 (not shown).

[0120] In yet another embodiment, proximal region 102a, tapered region 102b, and distal region 102c all comprise a first insulation layer, with at least two different materials used for the first insulation layer. With reference to FIG. 8D, electrosurgical device 100C comprises electrically insulated region 122 that includes three insulated regions 125a, 125b, and 125c, as described above for electrosurgical device 100B.

[0121] Proximal insulated region 125a comprises insulation layer 110c and second insulation layer 110b, middle insulated region 125b comprises insulation layer 110d and second insulation layer 110b, and distal insulated region 125c comprises only insulation layer 110d, as shown in FIG. 8D. Insulation layer 110c and insulation layer 110d may be any of the same materials as first insulation layer 110a described herein, however insulation layer 110c and 110d are different materials. In one example, insulation layer 110c is a PTFE spray coat applied to the core wire 118 prior to grinding. After grinding, insulation layer 110d is applied to the tapered region 102b and / or distal region 102c, which may be another PTFE spray coat, or may be a different material, for example ETFE, polyimide, parylene, or FEP.

[0122] With reference to FIG. 9, in another embodiment, electrosurgical device 100 comprises an inner elongate member 102’ with multiple varying diameter regions and multiple tapers. In one example, inner elongate member 102’ comprises core wire 118’ having a first portion P1 , second portion P2, and third portion P3. Each portion has a different outer diameter, D1’, D2’, and D3’ as shown in the figure, where D1’ > D2’ > D3’. Further core wire 118’ defines tapered regions 102d and 102e, which separate first, second, and third portions P1 , P2, and P3 respectively. In one specific embodiment, D1’ is between about0.2286 mm (0.009”) and 0.2794 mm (0.011”), for example about 0.254 mm (0.010”), D2’ is between about 0.1651 mm (0.0065”) and 0.2159 mm (0.0085”), for example about 0.1905 mm (0.0075”), and D3’ is between about 0.1016 mm (0.004”) and 0.1524 mm (0.006”), for example about 0.127 mm (0.005”).

[0123] In some embodiments, electrosurgical device 100’ further comprises a plurality of radiopaque marker bands 130. In some embodiments marker band 130 is the same size and material as support structure 112.Additional advantage specific to a TIPS procedure

[0124] One specific advantage to using this more flexible wire may be during a transjugular intrahepatic portosystemic shunt (TIPS) procedure. Such a method was disclosed in Baylis patent US 11 ,324,548. However, if an 0.889 mm (0.035”) RF wire (PoweWire) is used for this procedure, after the puncture is made, such a wire would not be able to track into the portal vein. That is, it would not be flexible enough to turn 90 degrees in a narrow blood vessel such as the portal vein.

[0125] The electrosurgical device 100 described herein may have sufficient pushability and flexibility to create a tract through the liver into the portal vein, and then “track” into the portal vein, without the need to swap for an 0.889 mm (0.035”) wire guide after the puncture. Thereby reducing the complexity of the procedure and the procedure time.

[0126] In other applications, electrosurgical device 100 may be used in pediatric cardiology applications, to puncture through cardiac tissue. Other potential applications are for biliary occlusions that are not inside blood vessels.

[0127] The embodiment(s) of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.

[0128] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

[0129] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation, or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

Claims

CLAIMS1 . An electrosurgical device for creating a channel through a region of tissue using energy, the electrosurgical device comprising: an electrically conductive elongate member; and an energy delivery component provided at a distal end of the electrosurgical device, the energy delivery component being electrically coupled to the electrically conductive elongate member, the energy delivery component having an outer diameter and a length; wherein the length of the energy delivery component is greater than the outer diameter of the energy delivery component.

2. The electrosurgical device of claim 1 , wherein the length of the energy delivery component is between about 1 .4 mm and about 2.5 mm and the outer diameter of the energy delivery component is between about 0.3 mm and about 0.4 mm.

3. The electrosurgical device of claim 1 wherein the energy delivery component is radiopaque.

4. The electrosurgical device of claim 1 , wherein the electrically conductive elongate member defines a proximal segment, a distal segment, and a tapered segment disposed between the proximal and distal segments, and wherein a diameter of the electrically conductive elongate member in the distal segment is smaller than a diameter of the electrically conductive elongate member in the proximal segment.

5. The electrosurgical device of claim 4 wherein the diameter of the electrically conductive elongate member in the distal segment is between about 0.1016 mm and about 0.1524 mm, and the diameter of the electrically conductive elongate member in the proximal segment is between about 0.2032 mm and about 0.2794 mm.

6. The electrosurgical device of claim 4 wherein a length of the tapered segment is between about 5 mm and about 7 mm and a length of the distal segment is between about 23 mm and 27 mm.

7. The electrosurgical device of claim 4, further comprising a rigidity component located about at least a portion of the distal segment.

8. The electrosurgical device of claim 7 further comprising a reinforcement structure located proximal of the rigidity component, the reinforcement structure surrounding the tapered segment.

9. The electrosurgical device of claim 1 wherein the electrically conductive elongate member defines a proximal segment, a distal segment, and an intermediate segment located between the proximal and distal segments, wherein a diameter of the electrically conductive elongate member in the distal segment is smaller than a diameter of the electrically conductive elongate member in the intermediate segment, and a diameter of the electrically conductive elongate member in the proximal segment is greater than the diameter of the electrically conductive elongate member in the intermediate segment.

10. The electrosurgical device of claim 9 wherein the electrically conductive elongate member defines a first tapered region and a second tapered region, the first tapered region located between the proximal segment andthe intermediate segment, and the second tapered region located between the intermediate segment and the distal segment.11 .The electrosurgical device of claim 4 further comprising an electrically insulative thermal shield disposed between the energy delivery component and an electrically insulated region.

12. The electrosurgical device of claim 11 , wherein the length of the energy delivery component is greater than a longitudinal length of the electrically insulative thermal shield.

13. The electrosurgical device of claim 11 , wherein the length of the electrically insulative thermal shield is between about 1.9 mm and about 2.1 mm.

14. The electrosurgical device of claim 1 wherein the electrically conductive elongate member comprises stainless steel.

15. The electrosurgical device of claim 7 wherein the rigidity component comprises a coil.

16. The electrosurgical device of claim 15 wherein the coil is radiopaque.

17. The electrosurgical device of claim 8 wherein the reinforcement structure comprises a hypotube.

18. The electrosurgical device of claim 11 wherein the electrically insulative thermal shield comprises platinum.

19. The electrosurgical device of claim 1 , wherein the energy delivery component comprises a tubular support structure and a distal tip, and wherein a distal portion of the electrically conductive elongate member is positioned through the tubular support structure, the tubular support structure defining a substantially planar distal face that is substantially perpendicular to a device longitudinal axis for enabling the distal tip to be formed integrally with a distal end of the electrically conductive elongate member.

20. The electrosurgical device of claim 1 , wherein the energy delivery component comprises a tubular support structure and a distal tip, and wherein a distal portion of the electrically conductive elongate member is positioned within the tubular support structure and the distal tip is formed integrally with a distal end of the electrically conductive elongate member.

21. The electrosurgical device of claim 20, wherein a diameter of distal tip is greater than a diameter of the tubular support structure.

22. The electrosurgical device of claim 11 further comprising an insulation layer covering a portion of the proximal segment and extending to at least a proximal end of the electrically insulative thermal shield.

23. The electrosurgical device of claim 22 further comprising an adhesive located between the electrically insulation thermal shield and the insulation layer.

24. The electrosurgical device of claim 22, wherein the insulation layer surrounds a proximal portion of the electrically insulated thermal shield.

25. The electrosurgical device of claim 24, wherein the electrically insulated thermal shield defines a reduced diameter proximal portion.

26. The electrosurgical device of claim 25 wherein the reduced diameter proximal portion defines a taper.

27. The electrosurgical device of claim 24 wherein a diameter of the electrically insulated thermal shield is smaller than the outer diameter of the energy delivery component.

28. The electrosurgical device of claim 9 further comprising a plurality of radiopaque support structures.

29. The electrosurgical device of claim 1 further comprising: a first insulation layer; a second insulation layer; an electrically exposed region for delivering energy to the region of tissue; and an electrically insulated region, the electrically insulated region comprising a proximal insulated portion and a distal insulated portion; wherein the first insulation layer surrounds the proximal insulated portion and the second insulation layer surrounds the first insulation layer and extends beyond the first insulation layer to cover the distal insulated portion.

30. The electrosurgical device of claim 4 further comprising:a first insulation layer; a second insulation layer; wherein the first insulation layer surrounds the proximal segment and the second insulation layer surrounds the first insulation layer and extends beyond the first insulation layer to cover the distal segment.

31. A low-profile electrosurgical device for creating a channel through a region of tissue using energy, the electrosurgical device comprising: an electrically conductive elongate member; and an energy delivery component provided at a distal end of the electrosurgical device, the energy delivery component being electrically coupled to the electrically conductive elongate member, the energy delivery component having an outer diameter and a length; wherein the length of the energy delivery component is greater than the outer diameter of the energy delivery component.

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