Abstract:
A method of deploying an antenna of an ablation device includes the step of placing an introducing member relative to tissue. The introducing member is disposed on a distal end of a handle member. The method also includes the steps of advancing an antenna distally through the handle member and at least partially through the introducer and rotating the handle member about the longitudinal axis thereof relative to the antenna. The method also includes the step of moving the handle member proximally along the longitudinal axis thereof to retract the introducer proximally relative to the antenna such that the antenna is at least partially deployed relative to the introducer to treat tissue.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to ablation devices and methods. More particularly, the disclosure relates to systems and methods for deploying an ablation antenna assembly into tissue. 
     2. Background of Related Art 
     Treatment of certain diseases requires destruction of malignant tissue growths (e.g., tumors). It is known that tumor cells denature at elevated temperatures that are slightly lower than temperatures injurious to surrounding healthy cells. Therefore, known treatment methods, such as hyperthermia therapy, heat tumor cells to temperatures above 41° C., while maintaining adjacent healthy cells at lower temperatures to avoid irreversible cell damage. Such methods involve applying electromagnetic radiation to heat tissue and include ablation and coagulation of tissue. In particular, microwave energy is used to coagulate and/or ablate tissue to denature or kill the cancerous cells. 
     Microwave energy is applied via microwave ablation antennas that penetrate tissue to reach tumors. There are several types of microwave antennas, such as monopole and dipole, in which microwave energy radiates perpendicularly from the axis of the conductor. A monopole antenna includes a single, elongated microwave conductor whereas a dipole antenna includes two conductors. In a dipole antenna, the conductors may be in a coaxial configuration including an inner conductor and an outer conductor separated by a dielectric portion. More specifically, dipole microwave antennas may have a long, thin inner conductor that extends along a longitudinal axis of the antenna and is surrounded by an outer conductor. In certain variations, a portion or portions of the outer conductor may be selectively removed to provide more effective outward radiation of energy. This type of microwave antenna construction is typically referred to as a “leaky waveguide” or “leaky coaxial” antenna. 
     SUMMARY 
     According to an embodiment of the present disclosure, a method of deploying an antenna of an ablation device includes the step of placing an introducing member relative to tissue. The introducing member is disposed on a distal end of a handle member. The method also includes the steps of advancing an antenna distally through the handle member and at least partially through the introducer and rotating the handle member about the longitudinal axis thereof relative to the antenna. The method also includes the step of moving the handle member proximally along the longitudinal axis thereof to retract the introducer proximally relative to the antenna such that the antenna is at least partially deployed relative to the introducer to treat tissue. 
     According to another embodiment of the present disclosure, an antenna assembly includes a handle member defining a longitudinal axis and having a feedline disposed on its distal end. The feedline extends along the longitudinal axis and includes an inner conductor disposed within an outer conductor. The inner conductor is deployable relative to the outer conductor and configured to deliver energy from an energy source to tissue. The antenna assembly also includes a first track portion disposed longitudinally along at least a portion of the handle member. The first track portion has a distal end intersecting a second track portion disposed perpendicular to the first track portion and latitudinal along at least a portion of the handle member. The second track portion intersects a proximal end of a third track portion disposed longitudinally along at least a portion of the handle member. The antenna assembly also includes an actuating member movable longitudinally within the first and third track portions to cause corresponding movement of the inner conductor along the longitudinal axis and latitudinally along the second track portion upon rotational movement of the handle member about the longitudinal axis. Proximal movement of the handle member along the longitudinal axis when the actuating member is substantially aligned with the third track portion causes corresponding proximal movement of the outer conductor and distal movement of the inner conductor such that the inner conductor is deployed relative to the outer conductor for treating tissue. 
     According to another embodiment of the present disclosure, a method of deploying an antenna of an ablation device includes the step of placing an introducing member relative to tissue. The introducing member is disposed on a distal end of a handle member. The method also includes the steps of advancing an antenna distally through the handle member and at least partially through the introducer and retracting the introducer within the handle member such that the antenna is at least partially deployed relative to the introducer to treat tissue. 
     According to another embodiment of the present disclosure, an antenna assembly includes a handle member defining a longitudinal axis and having a feedline disposed on its distal end. The feedline extends along the longitudinal axis and includes an inner conductor disposed within an outer conductor. At least a portion of the inner conductor is deployable relative to the outer conductor and is configured to deliver electrosurgical energy from an energy source to tissue. The antenna assembly also includes a first actuation member movable along a first track disposed longitudinally along at least a portion of the handle member to cause corresponding movement of the inner conductor along the longitudinal axis. The antenna assembly also includes a second actuation member movable along a second track having a latitudinal track portion and a longitudinal track portion each disposed along at least a portion of the handle member. Upon movement of the second actuation member along the latitudinal track portion into substantial alignment with the longitudinal track portion, the second actuation member is movable proximally along the longitudinal track portion to retract the outer conductor relative to the inner conductor such that at least a portion of the inner conductor is deployed relative to the outer conductor to treat tissue when the first actuation member is disposed at a distal end of the first track. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the presently disclosed ablation devices are disclosed herein with reference to the drawings, wherein: 
         FIG. 1  is a perspective view of an ablation device in accordance with an embodiment of the present disclosure; 
         FIG. 2A  is a schematic view of the ablation device of  FIG. 1  connected to a generator; 
         FIG. 2B  is a cross-sectional view of a portion of a feedline of the ablation device of  FIG. 2A  taken along section line  2 B- 2 B of  FIG. 2A ; 
         FIGS. 3A, 3B, and 3C  are perspective views of an ablation device in accordance with one embodiment of the present disclosure showing sequentially the steps for deploying the radiating tip; 
         FIGS. 4A, 4B, and 4C  are perspective views of an ablation device in accordance with another embodiment of the present disclosure showing sequentially the steps for deploying the radiating tip; 
         FIG. 5  is a schematic view of an ablation device connected to a generator in accordance with another embodiment of the present disclosure; and 
         FIGS. 6A and 6B  are perspective views of the ablation device of  FIG. 5  according to various embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the presently disclosed microwave ablation devices are described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein the term “distal” refers to that portion of the microwave ablation device, or component thereof, farther from the user while the term “proximal” refers to that portion of the microwave ablation device or component thereof, closer to the user. 
     An ablation device in accordance with the present disclosure is referred to in the figures as reference numeral  10 . While a microwave ablation device is described herein, it is contemplated that the present disclosure may also be used in connection with other types of ablation devices. Such ablation devices may include an antenna and/or an electrode. 
     Referring initially to  FIG. 1 , ablation device  10  includes an antenna  12  and a handle portion  13 . Antenna  12  includes a shaft or feedline  14  having an inner conductor  16  and an outer conductor  20 , which defines a longitudinal axis X-X. Outer conductor  20  may be, for example, an introducing structure (e.g., needle) configured to pierce and/or penetrate tissue. Ablation device  10  is connected by a cable  21  (e.g., coaxial cable) to a connector  15  that, in turn, operably connects ablation device  10  to a suitable electrosurgical generator  22  (see  FIGS. 2A and 5 ). Additionally, an actuation element  7  is illustrated in  FIG. 1  in accordance with various embodiments of the present disclosure. Actuation element  7  is operably coupled to inner conductor  16  and movable along a track  9  disposed longitudinally along at least a portion of the length of handle portion  13  to move inner conductor  16  along longitudinal axis X-X relative to outer conductor  20 . More specifically, distal and proximal actuation of actuation element  7  along track  9  moves inner conductor  16  distally and proximally along longitudinal axis X-X, respectively, relative to outer conductor  20 . Actuation element  7  may be, for example, a slide button, a ring, a lever, or any element ergonomically suited to be actuated along track  9 . 
     As seen in  FIG. 2A , inner conductor  16  includes a distal tip  17  and is extendable from outer conductor  20 . Several types of inner conductor  16  may be used in connection with the disclosed ablation device  10 , including an inner conductor configured to deploy substantially in line with outer conductor  20  (e.g.,  FIG. 2A ) and an inner conductor configured to deploy in a curved orientation along a curvilinear path to define an ablation region  39  (See  FIG. 5 ). In the illustrated embodiments of  FIGS. 2A and 5 , a proximal end of feedline  14  includes a coupler  18  that electrically couples antenna  12  to generator  22  via cable  21 . 
     In some embodiments, distal tip  17  allows for insertion of antenna  12  into tissue with minimal resistance. In those cases where the antenna  12  is inserted into a pre-existing opening, distal tip  17  may be rounded or flat. 
     As shown in  FIG. 2B , feedline  14  may be in the form of a coaxial cable. Portions of feedline  14  may be formed of outer conductor  20  surrounding inner conductor  16 . Each of inner conductor  16  and/or outer conductor  20  may be made of a suitable conductive metal that may be semi-rigid or flexible, such as, for example, copper, gold, or other conductive metals with similar conductivity values. Alternatively, portions of each inner conductor  16  and outer conductor  20  may also be made from stainless steel that may additionally be plated with other materials, e.g., other conductive materials, to improve their properties, e.g., to improve conductivity or decrease energy loss, etc. 
     With continued reference to  FIG. 2B , feedline  14  of antenna  12  is shown including a dielectric material  28  surrounding at least a portion of a length of inner conductor  16  and outer conductor  20  surrounding at least a portion of a length of dielectric material  28  and/or inner conductor  16 . That is, a dielectric material  28  is interposed between inner conductor  16  and outer conductor  20 , to provide insulation therebetween and is comprised of any suitable dielectric material. 
     In some embodiments, inner conductor  16  is configured to pierce or slice through tissue, either mechanically and/or with the aid of energy, e.g., radiofrequency or microwave. In the embodiment where inner conductor  16  mechanically pierces or slice through tissue, inner conductors  16  is thin enough to pierce or slice through tissue upon the exertion of a predetermined amount of force. Additionally or alternatively, inner conductor  16  may be configured to receive energy, e.g., from generator  22 , to piece or slice through tissue or assist in piercing or slicing through tissue. 
     With reference to  FIGS. 3A, 3B, and 3C , one embodiment of ablation device  10  includes a track  19  disposed along handle body  13  and including track portions  19   a ,  19   b , and  19   c . Track  19  operates similar to track  9  of  FIG. 1  and is described below to the extent necessary to detail the differences between the embodiments. Track portions  19   a  and  19   c  are disposed longitudinally along at least a portion of the length of handle body  13  and track portion  19   b  is disposed between and substantially perpendicular to track portions  19   a  and  19   c  about at least a portion of the circumference of handle body  13 . As substantially described above with respect to  FIG. 1 , actuation element  7  is operably coupled to inner conductor  16  and is movable along tracks  19   a ,  19   b , and  19   c .  FIGS. 3A, 3B, and 3C  illustrate distal actuation of actuation element  7  relative to handle body  13  according to one embodiment of the present disclosure. As will be discussed in further detail below, distal actuation of actuation element  7  along track portions  19   a  and  19   c  is configured to move inner conductor  16  distally along the longitudinal axis X-X. As shown in  FIG. 3A , distal translation of actuation element  7  along track portion  19   a , in particular, causes inner conductor  16  to move distally in the direction of directional arrow “A” such that the tip  17  of inner conductor  16  is proximate or adjacent a distal end of outer conductor  20 . 
     As shown in  FIG. 3B , rotation of handle body  13 , as indicated by rotational arrow “B”, causes actuation element  7  to move within track portion  19   b  away from track portion  19   a  and into substantial alignment with track portion  19   c . When actuation element  7  is positioned within track portion  19   b  and misaligned with track portion  19   a , as shown in  FIG. 3B , proximal movement of actuation element  7  relative to handle body  13  is restricted. As shown in  FIGS. 3B and 3C , distal movement of actuation element  7  beyond track portion  19   b  is permitted only when actuation element  7  is in substantial alignment with track portion  19   c.    
     Once actuation element  7  is positioned within track portion  19   b  away from track portion  19   a  and in substantial alignment with track portion  19   c  (See  FIG. 3B ), proximal movement of handle body  13 , as indicated by directional arrow “C” of  FIG. 3C , causes actuation element  7  to move distally along track portion  19   c . During proximal movement of handle body  13 , inner conductor  16  remains stationary relative to surrounding tissue and outer conductor  20  moves proximally in translation with proximal movement of handle body  13  to retract relative to inner conductor  16 , thereby exposing at least a portion of the length of inner conductor  16  to surrounding tissue. 
     With reference to  FIGS. 4A, 4B, and 4C , another embodiment of ablation device  10  includes a first track  29  and a second track  31  disposed within handle body  13 . Track  29  is disposed longitudinally along at least a portion of the length of handle body  13 . As substantially described above with respect to  FIG. 1 , actuation element  7  is operably coupled to inner conductor  16  and movable along track  29 . More specifically, distal and proximal actuation of actuation element  7  along track  29  moves inner conductor  16  distally and proximally along longitudinal axis X-X, respectively, relative to outer conductor  20 . 
     A second track  31  is disposed within handle body  13  offset an angular distance from track  29 , as best shown in  FIG. 4A , and includes track portions  31   a  and  31   b . In some embodiments, track  31  may be disposed on an opposing side of handle body  13  such that track portion  31   b  is offset or displaced an angular distance of between about 0° and about 180° from track  29 . Track portion  31   a  is disposed circumferentially within at least a portion of handle body  13  perpendicular to track portion  31   b  such that one end of track portion  31   a  intersects a distal end of track portion  31   b . Track portion  31   b  extends proximally from track portion  31   a  longitudinally along at least a portion of the length of handle portion  13 . An actuation element  8  is operably coupled to the outer conductor  20  and movable along track  31 . More specifically, distal translation of actuation element  8  along track portion  31   b  causes outer conductor  20  to move distally in the direction of arrow “A′” (See  FIG. 4A ) and proximal translation of actuation element  8  along track portion  31   b  causes outer conductor  20  to move proximally in the direction of arrow “B′” (See  FIG. 4C ). Movement of actuation element  8  along track portion  31   a  into substantial alignment with track portion  31   b  (See  FIG. 4B ) allows subsequent proximal movement of actuation element  8  along track portion  31   b , as indicated by directional arrow “C” of  FIG. 4C . This causes corresponding proximal retraction of outer conductor  20  within handle body  13  relative to inner conductor  16 , thereby exposing at least a portion of inner conductor  16  to surrounding tissue. 
     In one embodiment of ablation device  10 , shown in  FIG. 5 , inner conductor  16  is configured to deploy in a curved orientation along a curvilinear path to define ablation region  39 . More specifically, in response to the relative movement between outer conductor  20  and inner conductor  16 , at least a portion of inner conductor  16  is forced radially away from longitudinal axis X-X as shown in  FIG. 5 . In such an embodiment, at least a portion of inner conductor  16  may be flexible. 
       FIGS. 6A and 6B  show an ablation device  100  in accordance with embodiments of the present disclosure having an inner conductor  16  configured to deploy in a curved orientation as described above with reference to  FIG. 5 . In particular,  FIG. 6A  shows an embodiment of an ablation device  100  having a handle portion  113  including a trigger assembly  170  and a movable handle  140  movable relative to a stationary handle  150 . An antenna  112  is coupled to a distal end of the handle portion  113  and includes a feedline  114  having an inner conductor  116  and an outer conductor  120 . 
     A power transmission cord  120  is shown that connects ablation device  100  to a suitable electrosurgical generator (e.g., generator  22  of  FIG. 5 ). Trigger assembly  170  is configured to cause delivery of electromagnetic energy from the generator  22  to the inner conductor  116  via power transmission cord  120 . 
     Movable handle  140  is operably coupled to inner conductor  116  and movable relative to stationary handle  150  to cause movement of inner conductor  116  relative to outer conductor  120 . In some embodiments, movement of movable handle  140  toward stationary handle  150  advances inner conductor  116  distally relative to outer conductor  120  to expose at least a portion of the length of inner conductor  116  to surrounding tissue. In this scenario, inner conductor  116  may be incrementally advanced distally corresponding to repeated actuation of movable handle  140  relative to stationary handle  150 . Alternatively or additionally, movable handle  140  may be actuated toward stationary handle  150  and held in such actuated position to cause inner conductor  116  to continually advance distally until movable handle  140  is released and/or actuated away from stationary handle  150 . With this purpose in mind, ablation device  100  of  FIGS. 6A and 6B  includes any suitable number of electrical connections, configurations, and/or components (e.g., resistors, capacitors, inductors, rheostats, etc.), mechanical connections, configurations, and/or components (e.g., gears, links, springs, rods, etc.), and/or electro-mechanical connections, configurations, and/or components such that ablation device may function as intended and/or as described in embodiments disclosed herein. 
     In the illustrated embodiment, an optional actuation button  115  is disposed on a proximal end of handle portion  113  and is operably coupled to inner conductor  116 . Substantially as described above with reference to actuation of movable handle  140  relative to stationary handle  150 , actuation button  115  may be pressed repeatedly toward handle portion  113  to cause corresponding incremental distal advancement of inner conductor  116  and/or be pressed toward body portion  113  and held in such actuated position to cause corresponding continuous distal advancement of inner conductor  116 . 
     Proximal retraction of inner conductor  116  through outer conductor  120  and within handle portion  113  may be achieved through actuation of actuation button  115  and/or actuation of movable handle  140  relative to stationary handle  150  through either of the methods described above for distally advancing inner conductor  116 . 
     In some embodiments, actuation of movable handle  140  relative to stationary handle may be configured to cause distal movement of inner conductor  116  along the longitudinal axis X′-X′ and actuation of actuation button  115  may be configured to cause proximal movement and/or retraction of inner conductor  116  along the longitudinal axis X′-X′. 
     As shown in  FIG. 6B , actuation button  115  may be embodied as a plunger-type mechanism operably coupled to a distal end of an actuation rod  119  disposed linearly through handle portion  113  and operably coupled at a proximal end to inner conductor  116 . Actuation rod  119  defines a longitudinal axis X′-X′ about which actuation button  115  and actuation rod  119  may be rotated either clock-wise or counter clock-wise to effect rotation of inner conductor  116  and, thus, the location of ablation region  39  relative to surrounding tissue. Further, proximal and distal movement of actuation rod  119  along longitudinal axis X′-X′ may be effected by rotation of actuation button  115  and/or actuation rod  119 , pulling or pushing of actuation button  115  and/or actuation rod  119 , respectively, or any combination thereof. In this scenario, the plunger-type mechanism may be configured as a linear actuator utilizing electro-mechanical components and/or hydraulic components to advance and retract inner conductor  116 . With this purpose in mind and although not shown, handle portion  113  includes any suitable number of electrical connections, configurations, and/or components (e.g., resistors, capacitors, inductors, rheostats, etc.), mechanical connections, configurations, and/or components (e.g., gears, links, springs, rods, etc.), hydraulic connections, configurations, and/or components (e.g., pumps, motors, cylinders, valves, etc.), and/or electro-mechanical connections, configurations, and/or components such that ablation device may function as intended and/or as described in embodiments disclosed herein. 
     In some embodiments, the plunger-type configuration of actuation button  115  and actuation rod  119  may be configured to actuate in an incremental manner in response to corresponding actuation of movable handle  140  relative to stationary handle  150 , for example, in substantially the same manner as a caulking gun. More specifically, inner conductor  116  may be incrementally advanced distally relative to outer conductor  120  corresponding to repeated actuation of movable handle  140  relative to stationary handle  150 . Alternatively or additionally, movable handle  140  may be actuated toward stationary handle  150  and held in such actuated position to cause inner conductor  116  to continually advance distally until movable handle  140  is released and/or actuated away from stationary handle  150 . 
     In some embodiments, actuation of movable handle  140  relative to stationary handle may be configured to cause distal movement of inner conductor  116  along the longitudinal axis X′-X′ and actuation of actuation button  115  may be configured to cause proximal movement and/or retraction of inner conductor  116  along the longitudinal axis. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.