fig1 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 . as will be described below and shown in fig1 , 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 fig1 . referring to fig1 - 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 fig1 ) 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 . more in particular , referring to fig2 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 fig2 ) 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 fig4 a ). for example , fig4 a is a schematic view of the working end 115 with working surface ws in contact with targeted tissue t . as can be seen in fig4 a , 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 . the outer surface 160 typically defines a cylindrical envelope from which the offset housing 140 projects radially . in contrast , fig4 b 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 . 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 fig5 , 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 fig5 , 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 fig4 b . fig2 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 fig2 - 3 , it can be seen that window surface ws is offset from the shaft outersurface 160 by a predetermined dimension d which can be from 2 mm to 8 mm and in one embodiment comprises a 5 mm offset . as can be further be seen in fig2 - 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 . referring to fig2 - 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 hz to 500 hz . in fig3 , it can be understood that the electrode 145 has an elongated proximal shaft portion 176 that extends into handle 108 of the device ( fig1 ). the proximal end of electrode 145 is operatively coupled to a motor drive unit 148 and a suitable mechanism or controller is provided to move the elongated electrode proximal shaft portion 176 in an arc to resect tissue . as can be understood from fig2 - 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 electrode proximal shaft 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 elongated electrode proximal 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 . 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 fig6 , 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 fig6 , 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 . now turning back to fig1 , 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 fig1 , the introducer sleeve 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 to controller 155 and provide within a single cable a first lumen communicating with the fluid outflow pump 150 , a second lumen communicating with a fluid inflow pump 225 , and 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 fig1 , 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 reaction 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 . 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 fig1 ) 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 cam 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 . in another variation , the introducer sleeve assembly 102 can include a removable blunt tip obturator that can assist in atraumatic insertion in a patient &# 39 ; s urethra . referring to fig2 - 3 , one variation of the resecting device as described above has an electrode 145 with a resecting portion 149 that moves radially in an arc relative to axis 112 and a distal window 144 . another variation can provide an electrode 145 that reciprocates axially to move across the window 144 and would have similar effectiveness . referring back to fig1 , the electrode 145 comprises a first polarity electrode or active electrode and the shaft portion indicates that 245 comprise the return electrode . referring to fig1 , the resecting device 105 can be actuated by moveable finger grip 260 which is adapted to be squeezed toward fixed finger grip 262 to thus move the working end 115 and window surface ws axially back and forth to resect tissue . the physician can activate the electrosurgical function with a foot switch 265 ( fig1 ) and then reciprocate the working end 115 back and forth from about 5 mm to 25 mm to resect tissue in a path . at the same time , the physician can slightly rotate the shaft of the resecting device 105 so that the window surface ws engages a wider path in the targeted tissue surface . in typical use , the physician would stabilize the sleeve portion 240 and endoscope 130 , and then reciprocate and slightly rotate the resecting device 105 during a tissue resection procedure . during such a procedure , the physician can also slightly rotate the sleeve 240 and endoscope 130 to optimize viewing of the targeted tissue .
a tissue resecting device includes 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 move 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 .