Abstract:
A tissue resecting device includes an elongated shaft having a central axis, a distal end, and a proximal end. A ceramic or other housing is mounted at the distal end of the shaft and has a tissue-receiving window. A movable electrode is configured to be rotationally oscillated or otherwise moved across the window. In one instance, the rotatable moveable electrode may have a dogleg configuration with a free end constrained within an arcuate slot formed near the window. In another instance, the movable electrode may have a U-shaped configuration with a distal end coupled to a pivot in the housing which is aligned with a rotational drive member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional application No. 62/340,445 (Attorney Docket No. 42005-707.101), filed on May 23, 2016, the full disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention. The present invention relates to devices and methods for resecting and removing tissue from the interior of a patient&#39;s body, for example in a transurethral resection of prostate tissue to treat benign prostatic hyperplasia. 
         [0003]    Electrosurgical cutting devices often comprise a shaft or sleeve having a tissue extraction lumen with one or more radio frequency (RF) cutting blades arranged to resect tissue which may then be drawn into the extraction lumen, often via vacuum assistance through a cutting window. Most such electrosurgical tissue cutting devices rely on manually engaging the cutting window against the target tissue to be resected. While such manual engagement is often sufficient, in other cases, such as in laparoscopic procedures having limited access and field of view, the target tissue can be difficult to visualize prior to resection and, in particular, it can be difficult to assure that the optimum target site has been engaged by the cutting window. For these reasons, it would be desirable to provide improved electrosurgical cutting tools having improved visibility and ability to engage and immobilize tissue prior to cutting and to extract the tissue from tools after cutting. 
         [0004]    US2017/0105748, commonly owned with the present application and incorporated herein by reference herein, describes an improved electrosurgical cutting device comprising an elongated shaft having a central axis, a distal end, and an outer surface. An offset housing is mounted on the distal of the shaft and has a tissue-receiving window. The tissue-receiving window is offset radially outwardly from the outer surface of the shaft, and a moveable electrode is configured to oscillate back and forth across the window to resect tissue which extends into the window. The offset housing improves visibility of the cutting window when viewed from endoscopes and other visualization apparatus. 
         [0005]    While a substantial improvement over earlier electrosurgical cutting devices, the moveable electrode of the device of US2017/0105748 has a free distal end that is free-floating and which in rare instances can be caught by tissue and be lifted away from the ceramic housing. In other rare instances, the wire-like shaft of the devices of US2017/0105748 can potentially twist to an unwanted degree when the electrode engaged dense tissue. 
         [0006]    For these reasons, it would be desirable to provide improved electrosurgical cutting devices, of the type generally taught in US2017/0105748, where the motion of the moveable electrode is more stabilized and the shaft is less prone to twisting. At least some of these objectives will be met by the inventions described below. 
         [0007]    2. Description of the Background Art. US2017/0105748 has been discussed above. Other related patents and published applications include U.S. Pat. No. 8,221,404; U.S. Pat. No. 7,744,595; U.S. Pat. Publ. 2014/0336643; U.S. Pat. Publ. 2010/0305565; U.S. Pat. Publ. 2007/0213704; U.S. Pat. Publ. 2009/0270849; and U.S. Pat. Publ. 2013/0090642. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides improved devices and methods for resecting tissue. Devices according to the present invention include an elongated member having a ceramic or other housing at its distal end. The elongated member typically has an axial lumen extending between distal and proximal ends, and the lumen typically receives a rotatable shaft having a distal end which terminates near the window in the housing and a proximal end which is configured to connect to a motor, typically located in a handle at a proximal end of the elongated member. A moveable electrode is coupled to a distal end of the rotatable shaft, and the electrode usually comprises an active portion which is radially offset from a central axis of the rotatable shaft so that rotational oscillation of the rotatable shaft causes the active portion to reciprocate, i.e. sweep back-and-forth, across the window in the housing. 
         [0009]    In a first aspect of the present invention, the rotatable shaft comprises a tubular member having sufficient torsional strength or “stiffness” to resist twisting of the shaft while it is being rotationally oscillated or otherwise driven by the motor. In particular, the tubular member may comprise a rigid typically metal tube, usually having an insulative (electrically insulating) outer surface, often comprising a stainless steel tube covered by the insulated outer coating, sleeve, or the like. In more specific examples, the insultive outer surface may comprise a heat shrink polymer. 
         [0010]    It has been found that a tubular member, typically a stainless steeled tubular member, having a wall thickness of at least about 0.005 in., more typically at least about 0.010 in., will be sufficient to provide torsional strength necessary to resist twisting of the shaft during motor driven movement. 
         [0011]    In other specific aspects of this first example of the tissue resecting device of the present invention, the moveable electrode will have an active portion that extends across the tissue-receiving window with a profile that is substantially smaller than the window area. In this way, the active portion of the electrode will still leave a sufficient cross-sectional area of the window open to permit fluid aspiration around and past the active portion of the electrode even while the electrode is moving relative to the window. 
         [0012]    In still further specific examples of this first example of the tissue resecting device, the motor may be configured to drive the active portion of the electrode at an oscillatory rate equal to or greater than 1 cycle per second (CPS) relative to the window. In many instances, the oscillatory rate will be equal to or great than 5 CPS relative to the window. 
         [0013]    In still further specific aspects of this tissue resecting device, the active portion of the electrode may be offset outwardly from an axis of the rotatable electrode shaft by a distance of at least 2 mm, often by a length of at least 4 mm. 
         [0014]    In a second aspect or example of the present invention, a tissue resecting device comprises an elongated member having a proximal end and a distal end. A housing is located at the distal end of the elongated member, and the housing has a tissue-receiving window through a side portion or wall thereof. Both the elongated member and the housing are typically hollow and have lumens therethrough where the lumen in the elongated member is aligned with the lumen in the housing. In this way, a continuous path is formed from the window in the housing to the proximal end of the elongated member. A rotatable shaft extends axially through the elongated member, typically through the lumen thereof, from the proximal end to the distal end of the housing. A movable electrode is coupled to a distal end of the rotatable shaft. A means for constraining the movable electrode is provided so that the electrode will move across the window in a fixed path as the rotatable shaft is rotated. 
         [0015]    In a first specific embodiment, the means for constraining the movable electrode comprises a constraining channel located adjacent to a distal end of the window in the housing. A distal tip of the movable electrode travels in the constraining channel as the rotatable shaft is rotationally oscillated about its axis. Typically, at least an active of the movable electrode is radially offset from a rotational axis of the rotatable shaft. The constraining channel will usually have an arcuate path with a radius equal to the distance of the radial offset, and in this way the active portion of the electrode is able to track in the constraining channel as it is rotationally oscillated. 
         [0016]    In such specific embodiments where the distal tip follows in a constraining channel, the movable electrode is usually a continuous element with a “dogleg” shape with one end attached to the elongated member and a free end (the distal tip) traveling in the constraining channel. By “dogleg” shape, it is meant that the movable electrode will have a first straight portion disposed along an axis and an active portion radially offset from the first straight portion. The active portion will usually be aligned with the first straight portion along a parallel axis. The active portion will usually also be straight, but in other instances could be slightly curve or have irregular profiles. A lateral portion or segment of the movable electrode joins the first straight portion and the active portion so that the movable electrode is an integrated structure capable of conducing electricity, typically being an electrically conductive metal. At least the active portion of the movable electrode will be exposed to engage or contact tissue and deliver electrosurgical current, usually a cutting current, while other portions not intended to contact tissue may be covered with an insulating sleeve or other material. 
         [0017]    In a second specific embodiment, the constraining means may comprise a fixed pivot in a distal end of the housing where the pivot is axially aligned with an axis of the rotatable shaft. A distal tip of the movable electrode is axially aligned with the axis of the rotatable shaft and is rotatably coupled to the fixed pivot, and the active portion of the movable electrode is radially offset from the axis of the rotatable shaft, usually being formed with U-shaped deflection in a continuous metal element. A forward or free end of such the rotatable shaft can be rotatably coupled to the fixed pivot in order to constrain movement of the active portion of the movable electrode as the rotatable shaft is rotated. In particular, the active portion of the movable electrode will circumscribe an arcuate path with a center of rotation defined by the axis of the rotatable member. The arcuate path will usually span the entire width of the window and in some instances will extend beyond the sides or lateral edges of the window. The span of arcuate travel will usually be at least 5°, more usually being at least 10°, and frequently being in the range from 5° to 60°, often from 10° to 40°. 
         [0018]    Such tissue resecting devices will usually further comprise a motor configured to rotationally oscillate the rotatable shaft in order to move the electrode. The motor will typically be located in a handle permanently or removable attached to a proximal end of the elongated member. For example, the movable electrode may be adapted to move or reciprocate from side-to-side across the window. The motor drive may be further configured to oscillate the active portion of the electrode at a rate greater than or equal to 1 CPS and the window on the housing may be radially offset outwardly from the outer surface of the elongate member by at least 2 mm, frequently by at least 4 mm. 
         [0019]    The window in the ceramic or the housing may have two laterally spaced-apart edges or sides, where the movable electrode may further have a range of movement that extends the active portion thereof past these sides of the windows. Such sides of the windows may alternatively or additionally include ledges for receiving the electrode. 
         [0020]    All embodiments of the present invention will usually be configured to be attached to a negative pressure or vacuum source to in order to extract resected tissue through tissue extraction lumens in the elongated member and the housing. Usually but not necessarily, the rotatable shaft will also be located at least partially in such tissue extraction lumens, but in other instances the rotatable shaft may be located in separate lumen(s) in the elongated member and the housing. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a view of a tissue resecting device and a block diagram of systems and operating components corresponding to the invention. 
           [0022]      FIG. 2  is a perspective view of the working end of the resecting device of  FIG. 1  showing an asymmetric ceramic housing and moving electrode that is adapted to sweep across a tissue-receiving window. 
           [0023]      FIG. 3  is another perspective view of the working end of the resecting device of  FIG. 1  from a different angle. 
           [0024]      FIG. 4A  is a schematic view of the working end of  FIGS. 2-3  interfacing with tissue targeted for resection under endoscopic vision. 
           [0025]      FIG. 4B  is a schematic view of a working end of a prior art tubular cutting device used in a hypothetical resection procedure. 
           [0026]      FIG. 5  is another schematic view of the working end of  FIGS. 2-3  being used to resect targeted tissue to a significant depth from the organ surface. 
           [0027]      FIG. 6  is a perspective view of a distal dielectric housing of a working end similar to that of  FIGS. 2-3  showing window sides with ledges for receiving the electrode at the ends of its movement in a sweeping arc. 
           [0028]      FIG. 7A  is a perspective view of a distal ceramic housing of a working end similar to that of  FIG. 6  with the distal tip of the moveable electrode adapted to move in a constraining slot or channel. 
           [0029]      FIG. 7B  is a perspective view of an alternative ceramic housing similar to that of  FIG. 7A  with the distal tip of the moveable electrode adapted to pivot or rotate in a bore or pivot. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]      FIGS. 1  illustrates an electrosurgical tissue resecting system  100  for use in urological procedures to resect tissue that includes an introducer sleeve or sheath  102  and a hand-held single-use tissue resecting device or probe  105 . The resecting device  105  has a handle portion  108  that is coupled to an elongated shaft or extension portion  110  that has an outer diameter ranging from about 2 mm to 7 mm, and in one variation is 5 mm in diameter. The shaft  110  extends about longitudinal axis  112  to a working end  115  that is radially asymmetric relative the shaft  110  and its axis  112  as further described below. In one variation, the device is adapted for performing a TURP procedure (transurethral resection of prostate) or a bladder tumor resection procedure and thus the shaft portion  110  extends about axis  112  with a length suitable for introducing in a transurethral approach to reach the targeted prostate tissue or bladder tissue. 
         [0031]    As will be described below and shown in  FIG. 1 , the resecting device  105  is adapted for introduction through the introducer sleeve  102 . Such an introducer sleeve  102  is adapted to receive a commercially available endoscope  130  as can be understood from  FIG. 1 . 
         [0032]    Referring to  FIGS. 1-3 , in general, it can be seen the resecting device  105  has an elongated shaft  110  that extends to a distal shaft portion  132  that is coupled to an offset resecting housing  140  that has an offset tissue-receiving window  144 . A moveable electrode  145  is adapted to be driven by a motor drive unit  148  in handle  108  (see  FIG. 1 ) so that the longitudinal portion  149  of the electrode  145  sweeps across the window  144  from side to side to electrosurgically resect tissue that is captured in the window  144 . The targeted tissue can be suctioned into and captured in window  144  by means of a negative pressure source or outflow pump  150  in controller  155  that communicates with a tissue extraction channel  158  extending through the device  105  and terminating in the window  144 . 
         [0033]    More in particular, referring to  FIGS. 2 and 3 , the configuration of the offset housing  140  is adapted to perform multiple functions. First, the offset housing  140  positions the window surface WS (within curved plane P indicated in  FIG. 2 ) outwardly from the outer surface  160  of shaft  110  which then allows the window surface WS to be fully visible through a endoscope  130  or other viewing means that would be introduced parallel to the device shaft  110  (see  FIG. 4A ). For example,  FIG. 4A  is a schematic view of the working end  115  with working surface WS in contact with targeted tissue T. As can be seen in  FIG. 4A , the endoscope  130  is positioned with the field of view FV directly aligned with the working surface WS thus allowing optimal viewing of the tissue resection process. 
         [0034]    In contrast,  FIG. 4B  shows a working end  115 ′ of a conventional dual sleeve tubular cutter having a window surface WS′ which when pressed against an organ prevents endoscopic vision of the interface between the tubular cutting edge and the tissue T during a resection procedure. 
         [0035]    Second, the offset housing  140  is adapted for resecting tissue to a greater depth in a localized region of an organ, rather than resecting surface tissues over a broad area. More in particular as shown in  FIG. 5 , the offset portion  170  of housing  140  can be pushed into tissue perpendicular to axis  112  of the probe shaft  110 . Thus, as shown in  FIG. 5 , the offset housing  140  can be used to resect tissue deep into in a localized region that would not be possible with a resecting device having the configuration shown in  FIG. 4B . 
         [0036]      FIGS. 2 and 3  illustrate the asymmetric or offset dielectric housing  140  that can comprise a ceramic material such as zirconium oxide, aluminum oxide or similar materials as is known in the art. In  FIGS. 2-3 , it can be seen that window surface WS is offset from the shaft surface  160  by a predetermined dimension D which can be from 2 mm to 8 mm and in one embodiment comprises a 5 mm offset. 
         [0037]    As can be further be seen in  FIGS. 2-3 , the width W of the window surface WS around at least portions of the perimeter of the window  144  is a limited dimension, for example less than 3 mm, or less than 2 mm or less than 1 mm. which allows the offset portion  170  of housing  140  to be pushed into tissue perpendicular to the device axis  112  as the electrode  145  sweeps across the window  144 . 
         [0038]    Referring to  FIGS. 2-3 , one variation of resecting device  105  has an electrode  145  that can be tungsten or stainless steel wire that with electrode portion  149  adapted to sweep across the window  144  at any suitable rate, for example from 1 CPS (cycles per second) to 50 CPS or more. In  FIG. 3 , it can be understood that the electrode  145  has an elongated proximal shaft portion  176  that extends into handle  108  of the device ( FIG. 1 ). The proximal end of electrode  145  is operatively coupled to a motor drive unit  148  and a suitable mechanism or controller is provided to rotate the elongated electrode shaft portion  176  in an arc to resect tissue. 
         [0039]    As can be understood from  FIGS. 2-3 , the electrode portion  149  moves back and forth akin to a windshield wiper across window  144  in the offset housing  140 . A number of mechanisms can be used to effectuate the desired movements of the electrode, or the motor drive  148  simply can be controlled by software to move in intermittent clockwise and counter-clockwise directions. In one variation, the elongated proximal portion  176  of the electrode  145  will twist over its length and thus the motor drive  148  can be adapted to rotate the electrode shaft in an arc with radial angle which is greater than the window&#39;s comparable radial angle or arc. Thus, the electrode portion  149  can be expected to move back and forth entirely across the window even when meeting some tissue resistance by compensating for some twisting that is allowed in the proximal electrode shaft portion  176 . In one variation, the motor drive unit can be adapted to over-rotate the electrode shaft portion  176  at its proximal end by a selected amount which can be from 10° radial motion to 90° radial motion to compensate for twisting of the electrode shaft portion to insure that electrode portion  149  sweeps entirely across the surface of window  144 . 
         [0040]    In general, the window  144  in housing  140  can be configured to have a radial arc relative to the electrode shaft  176  ranging between 30° and 180°. In one variation of housing  140 ′ shown in  FIG. 6 , it can be seen that the electrode portion  149  has a range of motion that extends across the radial dimension of the window  144  to ensure that any tissue captured in the window is resected as the electrode portion  149  passes the window edges  182   a  and  182   b  to function like a shear or in a scissor-like manner. The electrode portion  149  moves over ledges  186   a  and  186   b  on either side of the housing  140 ′ and can bump into surfaces  190   a  and  190   b . By bumping into the surfaces  190   a  and  190   b , any over rotation in the electrode shaft  176  to accommodate twisting as described above can limit the rotation of the electrode portion in the housing  140 ′. Further, in  FIG. 6 , it can be seen that the distal tip  192  of electrode portion  149  extends distally beyond window  144  and onto distal ledge  194  in the housing  140 ′ to ensure tissue is resected by the electrode in the distal window region. 
         [0041]    Now turning back to  FIG. 1 , it can be understood that the resecting device  105  and endoscope  130  can be used with introducer sleeve assembly or sheath  102 . As shown in  FIG. 1 , the introducer assembly  102  has a proximal handle body  202  with a connector  204  that is adapted to couple to connector member  205 . The connector  205  is adapted to couple a conduit  206  to controller  155  and provide within a single cable the following: (i) a first lumen communicating with the fluid outflow pump  150 , (ii) a second lumen communicating with a fluid inflow pump  225 , and (iii) a third lumen communicating with a pressure sensor positioned in the controller  155  or in or near the connector  205 . As can be seen in  FIG. 1 , the introducer sleeve  102  can also accommodate an endoscope  130 . Thus, the introducer sleeve  120  can be assembled with the endoscope  130  (and without the resection device  105 ) and coupled by connector  205  to the controller  155  to provide an inflow of irrigation fluid from fluid source  226 , and outflow of irrigation fluid to collection reservoir  228  together with pressure sensing to allow the assembly to be used in a diagnostic procedure prior to a tissue resection procedure. In other words, the introducer sleeve  102  can function as a ‘continuous flow’ optical introducer for use in trans-urethral access to a targeted sire in the prostate or bladder. 
         [0042]    After the introducer sleeve assembly  102  is used for an initial diagnostic procedure, the endoscope  130  can be removed from the assembly  102  and connector  205  can be disconnected from handle body  205 . Thereafter, the sleeve portion  240  (see  FIG. 1 ) of introducer assembly  102  can be detached from proximal handle body  204  with the sleeve portion  240  remaining in the patient. Next, the endoscope  130  and connector  205  can be assembled with the resecting device  105  and the physician can insert the resecting device  105  through the sleeve portion  240  remaining in the patient to access the targeted site. The resecting device  105  and sleeve portion  204  in combination then provide lumens as described above for fluid inflows, fluid outflows and direct pressure sensing through lumens in connector  205 . 
         [0043]    Now turning to  FIG. 7A , a perspective view of a distal ceramic housing of a working end  246  similar to that of  FIG. 6  is shown. In this variation, the distal tip  248  of the moveable electrode  250  is configured to be constrained within a constraining slot or channel  252 . In other words, the distal electrode tip  248  is not free-floating as in the variation of  FIG. 6 . It has been found that an electrode with a free-floating distal tip can be caught by tissue and be lifted away from the ceramic housing  255 . Thus, in this variation the distal electrode tip  248  is constrained and cannot be tangled with tissue or lifted away from the ceramic housing and window  260 . The variation of  FIG. 7A  illustrates an arcuate slot or channel  252  that limits the movement of the electrode  250 . In all other respects, the working end functions as described previously. Further, the distal electrode portion  262  and channel  252  can be configured to allow the electrode to pass over the edges  264   a  and  264   b  of the window  260  as described above. 
         [0044]      FIG. 7B  shows another variation of working end  266  in which the electrode  270  has a distal tip  272  that is constrained in a pivot or bore indicated at  274 . In this variation, it can be seen that the electrode  270  has a U-shape with the distal tip  272  aligned with the electrode shaft portion  275  to allow the active electrode portion  277  to move from side to side relative to window  260  as described previously. 
         [0045]    In another aspect of the invention shown in  FIGS. 7A-7B , the electrode shaft portion  275  comprises a tubular member  280  which can comprise a metal hypotube, such as stainless steel or a similar material. In a previous variation as shown in  FIG. 6 , the electrode shaft portion comprised a wire element which could potentially twist to an unwanted degree when the electrode engaged dense tissue, for example. In this variation, it has been found that a metal hypotube with a suitable wall thickness can resist twisting when the electrode is being moved and engaging dense tissue. In one variation, the wall thickness of the tubular member  280  can be at these 0.005″ or at least 0.010″. 
         [0046]    In general, a tissue resecting device corresponding to the invention comprises an elongated member extending along a longitudinal axis to a distal portion having a window communicating with an aspiration source, an electrode having an electrode shaft with a central axis extending within the elongated member to an electrode working end wherein a portion of the electrode working end is offset from said central axis, and a motor configured to rotate the electrode shaft to cause the electrode working end to move relative to the window wherein the electrode shaft comprises a tubular member adapted to resist twisting of said shaft during motor driven movement thereof. Further, the tubular member can comprise a metal tube with an insulative outer surface layer  282 . The tissue tubular member can be a stainless steel tube with the insulative outer surface layer comprising a heat shrink polymer. 
         [0047]    In one variation, the electrode&#39;s working end has a profile that is substantially smaller than the area of the window to thereby permit fluid aspiration around the electrode working end at all times through the window as the electrode is moving relative to the window. This allows the negative pressure source to draw the tissue into the window interface, and maintains the tissue in the interface as the electrode cuts and extracts the resected tissue. In one variation, the electrode working end is motor driven and moves at a rate of equal to or greater than 1 CPS relative to the window, or equal to or greater than 5 CPS relative to the window. As described previously, the electrode working end can be offset radially outward from the shaft assembly by at least 2 mm or by at least 4 mm. 
         [0048]    In another aspect of the invention, the tissue resecting device comprises an elongated member extending to a distal housing having a tissue-receiving window, a moveable electrode configured to move across the window, and a motor configured to move the electrode wherein a distal tip of the electrode moves in a constraining channel in the housing. In another variation, the tissue resecting device comprises an elongated member extending to a distal housing having a tissue- receiving window, a moveable electrode configured to move across the window; and a motor configured to move the electrode wherein a distal end of the electrode is non-free floating or pivots in a pivot channel.