Abstract:
A cutting device for tissue separation includes a cutting edge using electrical energy such as RF power that is coupled to, but thermally insulated from, a catheter in an elongated medical device. Thermal insulation between a ring-type cutting device and the catheter is provided by a gap, slots within the ring, and/or slanted slots within the ring. In one embodiment, tissue separation occurs by rotation of a ring-type electrically-powered cutting edge having internal cross-bar elements. In an alternate embodiment, tissue separation occurs by longitudinal movement of an offset electrically-powered cutting edge that is pressed against tissue by an inflatable balloon. In a further alternate embodiment, a cutting edge is coupled longitudinally to a catheter, is provided electrical energy by wired connection to the braided catheter, but is thermally isolated from the catheter.

Description:
BACKGROUND 
     1. Field 
     The present invention relates to an electrosurgical device and, in particular, to a cutting device for use with a catheter device inserted into a body. 
     2. Background Art 
     Medicine is providing ever-increasing demands for devices that can navigate narrow passageways to a desired location within a body so that diagnostic and therapeutic procedures can be performed at that location. Currently, elongated medical devices such as catheters can extend into a body from outside via an access point through various connected passageways to a desired location. At this location, it is desirable that an electrosurgical procedure be one of the procedures that are made available. 
     An electrosurgical procedure involves a medical device that uses electrical energy to perform a procedure, such as coagulation, dissection, desiccation and cautery. The electrical energy can be provided in either direct current (DC) form or in alternating current (AC) form. However, low frequency electrical energy, including DC, can stimulate muscle and nerves and have potentially undesirable outcomes such as cardiac arrest, if not properly handled. Higher frequency electrical energy, and in particular electrical energy in the radiofrequency (RF) range, does not stimulate muscle or nerves, and can therefore be used to core and coagulate tissue. 
     Modern day elongated medical devices provide the ability for clinicians to navigate to remote and narrow locations within a body. To provide such access, these elongated medical devices must meet a wide variety of requirements such as a desired length and a sufficiently small outer diameter. Further, such a device must also have a sufficiently large inside diameter to permit navigation and delivery of the required functionality to the remote location. In the case of an RF-powered electrosurgical device located at the end of such an elongated medical device, the inside diameter needs to be both sufficiently large to transfer the required energy of the electrosurgical device, as well as provide sufficient diameter consistent with the aspiration requirements of the device. More specifically, sufficient electrical current needs to be delivered to support the RF power level desired at the particular location in the body. In the case of a coring procedure, the size of the inner diameter of the cutting device must also permit the required aspiration of cored tissue from that location. Further, it is necessary to ensure that the heat generated in the immediate vicinity of the cutting device be sufficiently isolated from the rest of the elongated medical device so that the elongated medical device does not deteriorate or self-destruct under the resulting thermal conditions. 
     BRIEF SUMMARY 
     What is needed is a cutting device suitable for coupling to an elongated medical device that can navigate a tortuous pathway within a body in a highly articulable fashion. In addition, it is desirable that the coupling from the elongated medical device to the cutting tip provide sufficient thermal isolation to permit operation without deterioration or self-destruction of distal portions of the elongated medical device. 
     In an embodiment of the present invention, a cutting device is provided that contains a substantially cylindrical body (e.g., ring) that has a peripheral cutting edge powered by electrical energy, such as RF energy, and is mechanically supported by one or more struts coupled to a catheter, but thermally isolated from the catheter. Thermal isolation is provided by inserting between the substantially cylindrical body and the catheter a material (e.g., air) that has a thermal resistance that is higher than the thermal resistance of the material (e.g., stainless steel) from which the substantially cylindrical body is formed. In one embodiment, an air gap is placed between the substantially cylindrical body (e.g., the ring) and the catheter. Thermal isolation can be further enhanced by the provision of slots in the ring. Additional thermal isolation can be provided by using slanted slots in the ring. The ring has an open interior that provides a channel for aspiration of the cored tissue. In further embodiments of the present invention, the open interior can be divided into four quadrants for separation of the tissue into four pieces, thereby allowing easier aspiration of the separated tissue. 
     In a further embodiment of the present invention, an RF-powered half-ring cutting device having a cutting edge is provided that is connected to one side of a catheter. On the opposing side of the catheter, an inflatable stabilization balloon is provided to provide mechanical support during operation of the cutting device. Lateral motion of the half-ring cutting edge results from external manipulation of the catheter that is coupled to the half-ring cutting edge. Thermal isolation is provided by use of thermally isolating materials at the junction between the half-ring cutting edge and the wire carrying the electrical current to the half-ring. 
     In a still further embodiment, an RF-powered substantially cylindrical body (e.g., ring) with cutting edge is connected via thermally insulating material to a catheter that includes a braided wire disposed within the catheter (either in the wall of the catheter or disposed in the lumen of the catheter). Electrical current is provided to the ring via one or more wires connected to the braided wire. 
     Further embodiments, features, and advantages of the invention, as well as the structure and operation of the various embodiments of the invention are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
       Embodiments of the present invention are described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. 
         FIG. 1  illustrates an elongated medical device to which a cutting device can be coupled. 
         FIG. 2  illustrates a cutting device, in accordance with an embodiment of the present invention. 
         FIG. 3  illustrates a front view of the cutting device, in accordance with an embodiment of the present invention. 
         FIG. 4  illustrates a usage model of the cutting device, in accordance with an embodiment of the present invention. 
         FIG. 5  illustrates another cutting device, in accordance with another embodiment of the present invention. 
         FIG. 6  illustrates still another cutting device, in accordance with another embodiment of the present invention. 
         FIG. 7  and inset  7 A illustrate a still further cutting device, in accordance with an embodiment of the present invention. 
         FIG. 8  illustrates a further view of the cutting device illustrated in  FIG. 7 . 
         FIGS. 9A and 9B  illustrate another cutting device, in accordance with an embodiment of the present invention. 
         FIG. 10  provides a flowchart of a method for applying an RF-based electrosurgical procedure in a body using a cutting device, according to an embodiment of the current invention. 
     
    
    
     The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. 
     DETAILED DESCRIPTION 
     This specification discloses one or more embodiments that incorporate the features of this invention. The disclosed embodiment(s) merely exemplify the invention. The scope of the invention is not limited to the disclosed embodiment(s). The invention is defined by the claims appended hereto. 
     The embodiment(s) described, and references in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such a feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
       FIG. 1  depicts an example of a delivery device in the form of an elongated medical device  100 , to which a cutting device (not shown) can be coupled. In exemplary embodiments, elongated medical device  100  is a flexible catheter or contains multiple flexible catheters. In various embodiments, elongated medical device  100  is an endoscope or other medical device. Elongated medical device  100  contains an elongated shaft  110  having a distal end  120  and a proximal end  130 . Connected to proximal end  130  is a handle  140 . Connected to distal end  120  is an interface  150  to the cutting device. Based on the location within the body for which access is sought, elongated shaft  110  can take on a wide variety of lengths. Ports  160 ,  170  and  180  provide access to one or more lumens of elongated medical device  100  to permit passage of other catheters or instruments (e.g., power to a cutting device, a vision system (e.g., fiber-optic device), an aspiration needle, a drug-delivery catheter, a biopsy instrument, a cutter, a balloon catheter, a electrocautery instrument, a hemostatic sealing instrument, etcetera). Some exemplary embodiments of elongated medical device  100  are described in U.S. patent application Ser. No. 12/862,677, filed Aug. 24, 2010 and entitled “Highly Articulable Catheter,” which is incorporated herein by reference in its entirety. 
       FIG. 2  depicts a cutting device  260 , in accordance with an embodiment of the present invention. Interface  150  to the exemplary delivery device (elongated medical device  100 ) contains an outer catheter  210 , inner catheter  220  and fiber optics  230 . In this illustration, cutting device  260  is coupled to inner catheter  220  using one or more struts  250 . Cutting device  260  is of a substantially cylindrical shape (e.g., ring-shaped) with a peripheral cutting edge  240 . Struts  250  provide both mechanical support, as well as electrical connectivity, to cutting device  260 . Struts  250  also provide a gap  270  between inner catheter  220  and cutting device  260 , so that gap  270  provides a thermal barrier to prevent significant heat transfer from cutting device  260  back to inner catheter  220 . In addition, struts  250  also provide sufficient open interior space so that aspirated tissue can be removed from the treatment site. In an exemplary embodiment, cutting device  260  has an outer diameter of about 2.5 mm (0.10 inches), a width (in the longitudinal direction of elongated medical device  100 ) of about 0.5-0.6 mm (0.020 to 0.025 inches), a wall thickness of about 0.125 mm (0.005 inches), and is separated by gap  270  of approximately 0.9 mm (0.035 inches). In other exemplary embodiments, cutting device  260  has ranges of dimensions such as an outer diameter of 2.3-3.2 mm (0.09-0.125 inches), a width of 0.5-1.9 mm (0.020 to 0.075 inches), a wall thickness of 0.0.8-0.5 mm (0.003-0.02 inches), and is separated by gap  270  of approximately 0.25-1.9 mm (0.01-0.075 inches). 
     In an exemplary embodiment of the present invention, three struts  250   a ,  250   b ,  250   c  are used to provide the coupling between cutting device  260  and inner catheter  220 . Struts  250   a ,  250   b ,  250   c  are positioned so as to ensure sufficient mechanical stability in all three degrees of freedom for cutting device  260 . Struts  250  extend into interface  150  and are mechanically secured therein. In the example embodiment described above, struts  250  can be approximately one inch in length, and thus the majority of the length of struts  250  is secured within interface  150 . At least one of the struts  250  is connected (via welding or any other suitable method of securing) to a wire within a lumen in inner catheter  220 , where the wire continues through the length of inner catheter  220  of elongated medical device  100  and finally emerges to be connected to an external electrical power supply. An exemplary electrical power supply is the Force FX™ RF electrosurgical generator that is manufactured by Valleylab, a division of Tyco Healthcare Group located in Boulder, Colo. With such an electrical connection, cutting device  260  is energized by the RF energy. Struts  250  can be made of any suitable material to provide the required mechanical strength and current carrying ability such as stainless steel. 
     In the exemplary embodiment shown in  FIG. 2 , cutting device  260  is a monopole device such that a return pad is required to be positioned on the body at a suitable location. Thus, electrical current such as RF current is emitted from cutting device  260  into the tissue immediately surrounding cutting device  260 . From this tissue, the RF current propagates towards the return pad at which point the RF current converges at the return pad and exits the body. 
     Cutting device  260  can be made of stainless steel, although many other materials can be used consistent with the need to provide a suitable cutting edge  240 , conduct electrical current such as electrical current in the RF frequency range, as well as handle the heat generated in the electrosurgical procedure. In a further embodiment, cutting edge  240  can be coated with silicone to avoid charring of the surrounding tissue, with the resulting difficulties posed by the aspiration of the charred tissue. In further additional optional embodiments, inner surface  285 , outer surface  280 , or both surfaces  280 ,  285  of cutting device  260  can be coated with silicone or a similar lubricious material. Coating inner surface  285  with a substance such as silicone facilitates a clean separation of tissue and subsequent tissue shrinkage, while coating outer surface  280  with silicone facilitates sliding in the immediate tissue environment. Silicone is one example of a coating. In fact, the coating can be any substance that provides either or both electrical insulation and thermal insulation. For example, a hydrophilic coating can be used to provide an electrically insulating layer, but not a thermally insulating layer. In a further embodiment, cutting device  260  can be used without any coating. For example, if hemostasis is desired, then no coating would be typically used, and the separated tissue will typically exhibit greater shrinkage than the shrinkage obtained with a coated embodiment. Depending on the electrosurgical procedure, the amount of RF power delivered to cutting device  260  can be, for example, up to 20 W. In a typical example, 20 W of RF power is delivered to cutting device  260 . 
       FIG. 3  illustrates a front view of another embodiment of cutting device  300 . In this embodiment, cutting device  300  includes peripheral cutting edge  320  and cross-bars  310  (including cross-bar segments  310   a ,  310   b ,  310   c ,  310   d ) which are arranged to be orthogonal to one another to form four (4) sections. In an exemplary embodiment as shown in  FIG. 3 , the four sections can be equal, i.e., quadrants. Cross-bars  310  are electrically connected to cutting edge  320  and are also energized with electrical energy. Thus, cross-bars  310  also provide additional cutting surfaces and thus this embodiment provides additional cutting surface area beyond that shown in the embodiment in  FIG. 2 . The sections (e.g., quadrants) are open in the interior and therefore these sections enable the aspiration of the cored tissue. Other arrangements and numbers of struts can be used so that the inner space is broken into two or more sections, and thereby fall within the scope of the present invention. Further, as noted above, the two or more sections can be non-equal and fall within the scope of the present invention. Cross-bars  310  using similar materials as mentioned for cutting device  260 , and include stainless steel. 
       FIG. 4  illustrates a usage model of a cutting device such as cutting device  300 . As  FIG. 4  illustrates, separation of tissue can be achieved by rotation of cutting device  300  in the direction indicated by arrows  402  while applying forward pressure in the direction indicated by arrow  404 , in connection with delivery of RF energy. Rotation of cutting device  300  can be performed by external rotation of the proximal end of the catheter to which cutting device  300  is coupled, e.g., inner catheter  220 . Tissue separation can be accomplished by rotation in either or both directions. Such rotation can be performed manually or automatically by a machine (e.g., a stepper motor). Upon separation of the tissue of interest, aspiration of the separated tissue proceeds by way of the interior of the sections of cutting device  300  and the interior of its attached catheter, e.g., inner catheter  220 . Cutting device  300  and its rotational mode of use is particularly appropriate for longer portions of tissue removal that require tunneling forward over an extended length, with separation and aspiration as one moves forward. For removing relatively small portions of tissue, some forward pressure of cutting device  260  will often be sufficient without requiring rotation. 
     With respect to the thermal environment, significant heat is dissipated locally in the immediate vicinity of cutting devices  260 ,  300 . Particularly vulnerable to the temperature increases is interface  150  of elongated medical device  100 . In order to provide sufficient electrical energy to cutting devices  260 ,  300  without a resulting destruction of the cutting device, thermal considerations must be accommodated in the design. In an exemplary embodiment of cutting devices  260 ,  300 , as noted above, a gap  270  (see  FIG. 2 ) is provided in series between cutting devices  240 ,  300  and the catheter to which it is attached, e.g., inner catheter  220 . The provision of gap  270  introduces additional thermal resistance and therefore heat is unable to travel as freely towards inner catheter  220 . This helps to protect the stability and integrity of inner catheter  220  and elongated medical device  100 . As noted above, in an exemplary embodiment, gap  270  is approximately 0.035 inches in width. Other dimensions can be used that are consistent with the need to provide a suitable thermal resistance between cutting devices  260 ,  300  and interface  150 . 
     In an alternative thermal embodiment as shown in  FIG. 5 , increased thermal resistance can be further achieved by the use of slots or other openings in the substantially cylindrical portion (ring-portion)  520  of cutting device  540 . For example,  FIG. 5  shows cutting device  540  having slots  530  that reduce the amount of thermally conducting material in the thermal pathway between peripheral cutting edge  510  and inner catheter  220 . Slots  530  decrease the ability for heat to travel from the heat source, namely cutting edge  510 , towards inner catheter  220  (not shown in  FIG. 5 ) via struts  250 . Instead of a thermal path that consists of an entire ring, much of the metal has been removed to form slots  530 , which thereby increases the thermal resistance. As known by one of ordinary skill in the relevant arts, increased thermal resistance diminishes the ability for heat to propagate to inner catheter  220 , increased temperature effects are confined to cutting edge  510 , and interface  150  and the rest of elongated medical device  100  is thereby protected from thermal damage. Example dimensions for slots  530  are: six slots having a width in the range of 0.13-0.76 mm (0.005-0.030 inches) and a length in the range of 0.13-0.76 mm (0.005-0.030 inches), although the number of slots and the dimensions can take on a wide range consistent with maintaining the structural integrity of substantially cylindrical portion  520  while providing an appropriate thermal resistance. 
     In a still further embodiment, thermal resistance is increased using slanted slots  620 , i.e., by placing the slots on an angle, as illustrated in  FIG. 6 . By placing slots  620  on an angle, the length of thermal path between the source of the heat at peripheral cutting edge  610  and the coupled catheter (e.g., inner catheter  220 ) via struts  250  is increased, which in turn raises the thermal resistance. Thus, for the same length of slot, slanted slots  620  lengthen the thermal path and thereby increase the thermal resistance. Example dimensions for slanted slots  620  are: six slots slanted at 30 degrees, having a width in the range of 0.13-0.76 mm (0.005-0.030 inches) and a length in the range of 1.3-7.1 mm (0.050-0.280 inches), although the number of slots, slant angle and the dimensions can take on a wide range consistent with maintaining the structural integrity of substantially cylindrical portion  620  while providing an appropriate thermal resistance. 
     In another embodiment of the present invention,  FIG. 7  illustrates a cutting device  700  with a cutting edge  710  adapted to separate tissue located in a lateral or side direction from the axial or longitudinal direction of cutting device  700 . As with the other embodiments, cutting device  700  can be coupled to elongated medical device  100 . In this embodiment, elongated medical device  100  includes outer catheter  760 , middle catheter  770 , vision system  780 , and inner catheter  790 . Inner catheter  790  is within middle catheter  770 , which in turn is within outer catheter  760 . Vision system  230  is disposed within a lumen of outer catheter  760 . Vision system  230  can be provided to facilitate illumination and viewing of the local surroundings of cutting device  700 . As shown in  FIG. 7 , elongated medical device  100  can be positioned in a body passageway by advancing it over an optional guide wire  702  which extends through a lumen of inner catheter  790 . Outer catheter  760  is retractable to expose cutting edge  710 , as shown in  FIG. 7 . When navigating elongated medical device  100  in a body passageway, outer catheter  760  would be in the non-retracted position so that cutting edge  710  is covered. Outer catheter  760  can be externally manipulated by a clinician at proximal end of elongated medical device  100 . Such manipulation can be either manual or through some automated means. 
     Cutting edge  710  is coupled to inner catheter  790 , and is located on a side of cutting device  700 . On the opposite side of cutting device  700  is a stabilization balloon  720 . Cutting edge  710  can be any shape but is typically semi-circular, or a portion thereof, and is moveable in a longitudinal direction. In an open position, cutting device  700  includes a cavity  706  coupled to a lumen within inner catheter  790  for aspiration of separated tissue. Tissue is separated when cutting edge  710  moves to the closed position (i.e., in a longitudinal direction away from proximal end  130  of elongated medical device  100  and moves against the tissue of interest. To facilitate such manipulation between the open position and closed position of cutting edge  710 , cutting edge  710  is coupled to inner catheter  790 . Inner catheter  790  can be manipulated by a clinician at the proximal end of elongated medial device  100 . Such manipulation of cutting edge  710  can be either manual or via some automated means. 
     Cutting edge  710  is provided energy via a conductor or wire  740 , as illustrated in the cross-section view in inset  FIG. 7A . Providing thermal resistance is support structure  750  that provides support for wire  740  and is connected to cutting edge  710 . Wire  740  is electrically connected to cutting edge  710 , while support structure  750  provides the mechanical coupling between cutting edge  710  and inner catheter  790 . Support structure  750  can be made of any material that provides sufficient mechanical support but high thermal resistance. Such a material includes bakelite. Wire  740  is disposed within a lumen within inner catheter  790  and finally out to an external electrical power supply (not shown), e.g. an RF power supply. As before, an exemplary RF power supply is the Force FX™ electrosurgical generator manufactured by Valleylab, a division of Tyco Healthcare Group located in Boulder, Colo. Cutting edge  710  can be made of stainless steel, although many other materials can be used consistent with the need to provide a suitable cutting surface, conduct RF electrical current, as well as handle the heat generated in the electrosurgical procedure. Cutting edge  710  can be coated with silicone to avoid charring of the surrounding tissue, with the resulting difficulties in aspiration the charred tissue. 
     On the opposing side of inner catheter is a stabilization balloon  720 . Stabilization balloon  720  is coupled via a lumen within middle catheter  770  to a source of gas (such as air) or fluid (such as saline) that can be used for inflation. Inflation of stabilization balloon  720  applies a force that ensures cutting edge  710  is positioned or wedged against the tissue of interest. Then, the clinician manipulates the energized cutting edge  710  as noted above. Separate tissue can be aspirated via a lumen within inner catheter  790 . Example dimensions for cutting edge  710  are about 0.25 mm (0.010 inches) in diameter, about 0.50 mm (0.020 inches) in width, with about 0.13 mm (0.005 inches) in thickness. Example dimensions for stabilization balloon  720  are about 5.1 mm (0.20 inches) in length. Stabilization balloon  720  can be made of any suitable material to provide repetitive inflation and deflation in a biocompatible manner, and such materials include silicone. 
       FIG. 8  provides a further view of cutting device  700 . Aspiration ports  730 A and  730 B are shown inside inner catheter  790  whereby cored tissue can be aspirated into one or more lumens within inner catheter  790 . 
       FIGS. 9A and 9B  illustrate a further embodiment of a cutting device  900 . Cutting device  900  can be connected to an inner catheter of elongated medical device  100 . Cutting device  900  includes an interface section  910 , followed by a thermally insulating section  920 , which in turn is followed by a cutting tip  930 . Interface section  910  can include an outer surface coating using a thermoplastic elastomer such as polyether block amide (e.g., PEBAX™). Thermally insulating section  920  includes one or more segments of a thermally insulating material. Thermally insulating section  920  can be composed of any thermally insulating material such as polyimide. Thermally insulating section  920  provides a thermal resistance that limits the conduction of heat from cutting tip  930  to the succeeding sections such as interface section  910 , and elongated medical device  100 . On the internal side of thermally insulating section  920  is a liner made from a material such as fluorinated ethylene propylene (FEP), a fluorocarbon-based plastic with good electrical insulating properties and chemical and heat resistance. Other materials with similar properties can also be used. Cutting edge  930  receives electrical energy (e.g., RF energy) via one or more wires  940  coupled to braided wire that forms a part of (or is disposed within a lumen of) the inner catheter of elongated medical device  100 . Coring of tissue occurs by forward longitudinal motion of cutting tip  900 . As before, cutting edge  930  can be coated with silicone to avoid charring of the surrounding tissue, with the resulting difficulties in aspiration the charred tissue. Example dimensions of cutting tip  930  are an inner diameter approximately that of the inner diameter of the inner catheter of elongated medical device  100 , a length less than about 2.5 mm (0.1 inches) and a wall thickness similar to the wall thickness of the inner catheter of elongated medical device  100 . 
     Embodiments of the present invention can be realized in the foam of various endoscopes and other catheter-based devices to support electrosurgical medical procedures in pulmonology, cardiology, urology, gastroenterology and neurology, or any procedure involving a hollow organ. Access by the present invention to the desired site within the body can be by any natural orifice, small incision or through the use of any minimally invasive surgery in order to perform the desired task. Such access points include but are not limited to mouth, nose, urethra, and radial, jugular and femoral arteries. Lengths of the elongated medical device  100  (to which various cutting devices can be attached) can range from 1 cm (as would be applicable in certain brain procedures), to a 5 cm length bronchoscope for use in a procedure on a small infant, to lengths in excess of 130 cm for use in various scopes such as endoscopes and bronchoscopes for adult procedures. In a one example embodiment for use in a flexible bronchoscope, elongated shaft  110  would be about 62.5 to 125 cm (25 to 50 inches) long, with outer catheter  210  having an outer diameter of about 4.2 mm and an inner diameter about 2.8 mm and inner catheter  220  having an outer diameter of about 2.7 mm and a lumen with an inner diameter of about 2.6 mm. 
       FIG. 10  provides a flowchart of an exemplary method  1000  to provide a method for coring tissue at a desired position within a body, according to an embodiment of the present invention. 
     The process begins at step  1010 . In step  1010 , an elongated medical device  100  having an outer catheter  210  and an inner catheter  220  is inserted into a body and navigated to the desired position for an electrosurgical procedure using a cutting device as disclosed herein. 
     In step  1020 , RF power is applied to the cutting device and tissue is cored by mechanical manipulation of the cutting edge. Mechanical manipulation proceeds by way of forward motion of cutting device  260 , rotation of cutting device  300 , by to-and-fro motion of cutting device  700 , or by way of forward motion of cutting tip  930 . 
     In step  1030 , aspiration of the cored tissue occurs via a lumen within the associated catheter, e.g., inner catheter  220 . 
     It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the appended claims in any way. 
     The present invention has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. 
     The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance. 
     The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.