Abstract:
A surgical snare instrument according to several embodiments includes a first handle capable of controlling the rotational position of the snare, and a second handle adapted to control the opening and closing of the snare and cauterization. The first handle serves as a grippable element on the sheath and contains a system which rotates the shaft, and consequently the snare, so that when the physician grips the first handle, the physician is capable of steering the snare by operating the first handle. In addition, the physician is also capable of positioning the entire sheath relative to the endoscope by sliding the sheath into and out of the working channel of the endoscope. The proximal handle is operable by an assistant and permits longitudinal movement of the shaft and cautery application. According to other embodiments, the snare instrument is provided with a mount which enables the snare instrument to be adjustably fixed relative to an endoscope handle. Additionally, an embodiment is also provided in which a single handle provides a physician with a system which advances and retracts the sheath of the snare instrument relative to the endoscope, a system which opens and closes the snare, and a system which rotates the shaft and the snare to position the snare over a polyp.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates broadly to surgical instruments. More particularly, this invention relates to a surgical snare instrument for excising polyps.  
         [0003]     2. State of the Art  
         [0004]     Polypectomy snare instruments are used for the endoscopic removal of hypertrophic tissue growths within a body cavity, and particularly within the colon. Polypectomy snare instruments generally include an elongate tubular member, such as a catheter sheath, a shaft extending through the tubular member, an elastic wire forming a snare (loop) at the distal end of the shaft, and a handle for moving the shaft distally and proximally within the tubular member. The snare can be opened by moving the snare beyond the distal end of the sheath and closed by retraction of the snare into the tubular member, each effected by movement of the shaft relative to the sheath.  
         [0005]     In operation, a physician introduces the distal end of the instrument, with the snare of the snare instrument in a retracted position, through the working channel of an endoscope until the sheath begins to extend out of the distal end of the endoscope. The physician then directs an assistant, who has control of the handle of the snare instrument, to open the snare. The assistant accomplishes this function by moving two portions of the handle relative to each other. The physician then advances and retracts the sheath into and out of the endoscope, while applying torque to some portion of the instrument to position the snare loop over and around a polyp. Once the snare loop is positioned around the polyp, the physician orders the assistant to close the snare around the polyp. Then, the physician or assistant energizes a source of electrocautery current coupled to the shaft to desiccate, sever, and cauterize the polyp. Finally, the polyp is removed by withdrawing the snare (or, in some cases, the polyp is retrieved by use of another instrument such as a biopsy forceps). In a variation of the procedure, the physician uses suction applied to a channel of the endoscope to remove the polyp or to hold it to the end of the endoscope.  
         [0006]     Prior art snare instruments have several problems. First, it is difficult for the physician to precisely position the snare because the physician relies on gripping the small, slippery sheath over the shaft near where the sheath enters the endoscope handle. Typically, it is necessary for the physician to repeatedly push, pull, and torque the sheath and the shaft of the instrument in order to achieve the desired position with the snare around the polyp. Second, the prior art instruments are not capable of efficient steering, because the shaft which is generally used is a cable having low torsional stiffness, and is not usually free of camber or “set”. The result of these defects is that when the instrument is used in a tightly-flexed endoscope, the distal end of the snare does not respond directly to torsional input on the shaft where it enters the endoscope handle; i.e., rather than directly respond to torsional input from the physician, the shaft stores the torsional force and upon reaching a threshold, uncontrollable rotationally whips to release the force. Third, while several attempts have been made at providing a snare instrument with a handle adapted to more adeptly steer the snare, most of such prior art instruments do not specifically allow for rotating the snare to position it relative to the polyp. Rather, the physician must rotate the shaft of the instrument by tightly gripping and rotating the sheath where it enters the endoscope to try to maneuver the snare over the polyp. In addition, in the several prior art devices specifically adapted for rotational control, e.g., U.S. Pat. No. 5,066,295 to Kozak et al. and U.S. Pat. Nos. 3,955,587, 4,256,113, and 4,294,254 to Chamness et al., the rotational control function is placed in the handle at the proximal end of the instrument. This handle then controls the extension and retraction of the snare loop as well as the rotation of the snare loop. However, this handle is typically held by the assistant, so the physician must orally direct the assistant to coordinate the handle controls while the physician moves the jacket in and out of the endoscope. As a result, these instruments have not been widely accepted by physicians.  
       SUMMARY OF THE INVENTION  
       [0007]     It is therefore an object of the invention to provide a snare instrument which permits the physician to control all aspects of positioning the snare loop relative to the polyp, while allowing the assistant to perform the cauterizing and severing of the polyp.  
         [0008]     It is a further object of the invention to provide a snare instrument which provides to the physician the means for advancing and retracting the distal end of the snare instrument through the endoscope, as well as rotating the snare, and which provides to the assistant the means for extending and retracting the snare loop from the sheath of the snare instrument.  
         [0009]     It is another object of the invention to provide a snare instrument in which the physician has direct and immediate control of the entire instrument.  
         [0010]     It is also an object of the invention to provide a snare instrument which obviates the need for an assistant during a polypectomy procedure.  
         [0011]     It is yet another object of the invention to provide a snare instrument which improves the speed and efficiency of a polypectomy procedure.  
         [0012]     In accord with these objects, which will be discussed in detail below, a surgical snare instrument is provided. The snare instrument includes an elongate flexible tubular sheath, a flexible shaft extending through and axially movable relative to the sheath, a snare coupled to or formed at the distal end of the shaft, and a system to move the shaft, and consequently the snare, relative to the sheath. According to several embodiments of the invention, the system for moving the shaft relative to the sheath includes a first (physician&#39;s) handle capable of controlling the position of the snare, and a second (assistant&#39;s) handle proximal the first handle and adapted to control contraction of the snare and cauterization. The handles are coupled by a tubular sheath extension.  
         [0013]     The physician&#39;s handle is preferably positioned along the sheath of the snare instrument so that it is a few inches proximal to the entry port of the endoscope handle when the distal end of the sheath is adjacent to the distal end of an endoscope. The physician&#39;s handle serves as a grippable element on the sheath and contains a rotating means for rotating the shaft, so that when the physician grips that handle the physician is capable of steering (rotating) the snare by operating the rotating means. In addition, the physician is also capable of positioning the entire sheath relative to the endoscope by sliding the sheath into and out of the working channel of the endoscope. The proximal handle is operable by an assistant and permits longitudinal movement of the shaft and snare and the application of a cautery current to the shaft and snare.  
         [0014]     According to other embodiments, the snare instrument is provided with a connector which enables the snare instrument to be fixed relative to an endoscope handle. Additionally, an embodiment is also provided in which a single handle provides a physician with means for advancing and retracting the sheath of the snare instrument relative to the distal end of the endoscope, means for advancing (opening) and retracting (closing) the snare relative to the distal end of the sheath, and means for steering (rotating) the snare to position the snare over a polyp. Since the physician has direct and immediate control of the entire instrument, the snare instrument obviates the need for an assistant during the procedure, and improves the speed and efficiency of the polypectomy procedure. Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is broken side elevation in section of a first embodiment of a snare instrument according to the invention;  
         [0016]      FIG. 2  is an enlarged cross-section taken through line  2 - 2  in  FIG. 1 ;  
         [0017]      FIG. 3  is an enlarged cross-section taken through line  3 - 3  in  FIG. 1 ;  
         [0018]      FIG. 4  is an enlarged cross-section taken through line  4 - 4  in  FIG. 1 ;  
         [0019]      FIG. 5  is a broken section view of a physician&#39;s handle assembly according to a second embodiment of the snare instrument of the invention;  
         [0020]      FIG. 6  is an enlarged cross-section through line  6 - 6  in  FIG. 5 , showing the engagement of a key in a knob shaft;  
         [0021]      FIG. 7  is an enlarged cross-section through line  7 - 7  in  FIG. 5 , at a location proximal of the key;  
         [0022]      FIG. 8  is a broken section view of a third embodiment of the snare instrument according to the invention;  
         [0023]      FIG. 9  is an enlargement of the area between lines  9   a - 9   a  and  9   b - 9   b  in  FIG. 8 ;  
         [0024]      FIG. 10  is a broken section view of a fourth embodiment of the snare instrument of the invention; and  
         [0025]      FIG. 11  is a broken section view of a fifth embodiment of the snare instrument of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     Turning now to  FIG. 1 , a first embodiment of a surgical snare instrument  10  according to the invention is shown. The snare instrument  10  includes an elongate flexible tubular sheath  12  having a proximal end  14  and a distal end  16 , a flexible shaft  18  having a proximal end  20  and a distal end  22  extending through and axially movable relative to the sheath  12 , a snare  24  coupled to or formed at the distal end  22  of the shaft  18 , preferably adjacent the distal end  16  of the sheath  12 , and first and second handle assemblies  26 ,  28 , respectively, for moving the shaft  18  relative to the sheath  12 .  
         [0027]     The shaft  18  is preferably a high strength, straightened (camber-free) stainless steel wire of high elastic limit. The shaft  18  is adapted to be bent through a tortuous path without permanent deformation. In addition, since the shaft  18  is free of camber, it is possible to precisely rotate the snare  24  by rotating the shaft at any point along its length.  
         [0028]     Referring now to  FIGS. 1 through 3 , the physician&#39;s handle assembly  26 , which is the more distal of the two handles, generally includes a body  30  and a knob  32  mounted in the body  30  on bearings  33   a,    33   b  in a manner which permits the knob  32  to rotate coaxially relative to the body. The body  30  includes a central bore  34  with one or more apertures  35 , a threaded distal end  36 , and a threaded proximal end  38 . The sheath  12  of the snare instrument  10  is connected to the threaded distal end  36  of the body  32 , e.g., by means of a flare-nut connection  42 . Preferably, a stiffening sleeve  44  is provided over the sheath  12  at the connection  42 . The knob  32  includes a non-circular bore  40 , e.g., having the cross-sectional shape of a square. The knob  32  (for reasons discussed below) is preferably at least as long as the distance of movement required to open and close the snare  24 ; i.e., the length of the snare when compressed in the sheath  12 . The apertures  35  provide access to the knob  32 , so that the knob  32  can be rotated relative to the body  30 , e.g., by a physician.  
         [0029]     A portion of the shaft  18  extending through the bore  40  of the knob  32  is provided with a key  46 ; that is, a spline element fixed on and about the shaft  18  or, alternatively, rigidly and fixedly interposed between two portions of the shaft. The key  46  preferably has a rectangular shape but may have another non-circular shape. The key  46  is slidably axially movable within the bore  40 . Therefore, the shaft  12  may be moved axially through the bore  40  (and that is why the length of the knob  32  is preferably at least as long as the distance of movement required to open and close the snare). However, when the knob  32  is rotated relative to the body  30 , the key  46  within the bore  40  is rotated and, consequently, the shaft  18  and snare  24  are rotated relative to the sheath  12 .  
         [0030]     The distal handle assembly  28  is preferably positioned approximately 210 cm from the distal end  16  of the sheath  12  for a snare instrument  10  designed to be inserted into a 200 cm endoscope. Thus, the physician can grip the body  30  in a manner which permits rotating the knob  32  relative to the body, and hence the snare  24  relative to the sheath  12 , while using the body  30  as a grip to axially position the snare instrument  10  within the working channel of an endoscope.  
         [0031]     The shaft  18  extends out of the proximal end  38  of the body  30  to the proximal handle assembly  28 , or assistant handle. The proximal handle assembly  28  preferably includes a stationary member  50  and a spool member  52  slidable relative to the stationary member. The stationary member  50  includes a longitudinal throughbore  56  through which the proximal end  20  of the shaft  18  extends, a transverse slot  58 , a proximal thumb ring  60 , and a distal threaded connector  62 . The proximal end of the shaft  18  is preferably provided with a conductive stiffening sleeve  64 , and a cylindrical conductive bearing  66  is coupled about the proximal end of the stiffening sleeve  64 . The spool member  62  includes a cross bar  68  which extends through the transverse slot  58  to secure the spool member  52  on the stationary member  50 . In addition, the spool member  62  preferably includes a cautery plug  70 . The conductive bearing  66  extends through the cross bar  68  and a collar  74  secures the bearing  66  in the cross bar  68  in a manner which permits the conductive bearing to freely rotate within the cross bar  68 . A spring  72  extends between the cautery plug  70  and the conductive bearing  66 , and provides a contact between the plug  70  and the bearing  66  regardless of the rotational position of the bearing  66 . Movement of the spool member  52  relative to the stationary member  50  causes the snare  24  to extend from and retract into the distal end  16  of the sheath  12 .  
         [0032]     Referring to  FIGS. 1 and 4 , an electrically insulative extension sheath  80  extends over the shaft  18  between the proximal end  38  of the body  30  and the distal end  62  of the stationary member  50 , coupled, e.g., via flare-nut connections  82 ,  84 . Thus, there is a continuous outer connection joining, yet spacing apart, the distal handle assembly  26  and the proximal handle assembly  28 . A stiffening sleeve  86  is preferably provided over the extension sheath  80  at the proximal end  38  of the body  30 , and another stiffening sleeve  88  is preferably provided over the extension sheath  80  at the distal end  62  of the stationary member  50 .  
         [0033]     In use, the physician introduces the snare instrument  10  into the endoscope (not shown), typically by means of a port in the endoscope handle which communicates with the working channel of the endoscope. Then, the physician gives the proximal assistant&#39;s handle  28  to the assistant. The physician then grips the body  30  of the distal physician&#39;s handle  26  of the snare instrument and uses it to position the distal end  16  of the sheath  12  adjacent to the polyp to be excised. The physician then instructs the assistant to extend the snare, which is performed by moving the spool member  52  relative to the stationary member  50 . The physician then uses the distal handle  26  to simultaneously axially position and rotate the snare over the polyp. Then, the physician instructs the assistant to close the snare and sever the polyp, using cautery if desired. In this manner, the physician controls the means of positioning the snare onto the polyp, and the assistant controls the opening and closing of the snare and the cauterization.  
         [0034]     In the first embodiment, as discussed above, it will be appreciated that the knob  32  is preferably at least as long as the distance of movement needed to open and close the snare  24 . However, turning now to  FIGS. 5-7 , according to a second embodiment of a snare instrument  110 , the key  146  on the shaft  118  is made sufficiently small in diameter such that it can pass partly into the bearings  190 ,  191  on the body  130  (which support the knob  132 ) and proximal and distal ends  136 ,  138  of the body  130 , or even into the sheath  112  and extension sheath  180 , and their respective stiffening sleeves. Accordingly, the knob  132  is provided with a hollow knob shaft  192  having a non-circular bore  140  which rotatably engages the key  146  on the instrument shaft  118 . The knob shaft  192  extends beyond the proximal and distal ends of the knob  132 . The knob shaft  192  extends into bearings  190 ,  191  of the body  130  which allows the knob  132  and knob shaft  192  to spin within the body  130 . The knob shaft  192  may optionally extend through the proximal and distal ends  136 ,  138  of the body  130 , into the sheath (on the distal end) and into the extension sheath (on the proximal end). In this manner, it is possible to achieve a large range of axial motion (e.g., 3.5 inches) while having a knob  132  of much shorter dimension (e.g., 1.25 inches). It should be noted that if the key  146  has a substantial length (e.g., 0.75 inch), the body  130  and knob  132  can be made even shorter, since it is necessary for only a portion of the key  146  to be engaged with the non-circular bore  140  of the knob shaft  192  at any time.  
         [0035]     In addition, while the first embodiment describes a shaft  18  that is monolithic and continuous from the snare  24  to the proximal handle assembly  28 , the shaft may alternatively be a composite structure. Specifically, referring to  FIGS. 8 and 9 , according to a third embodiment of the invention, the straightened, torsionally-stiff, camber-free section of the shaft  218  need only extend from the snare to the knob  232 . A swivel joint  290  may be interposed on the shaft  218  between the knob  232  and the proximal handle assembly, and join the shaft  218  to a flexible or stiff proximal shaft extension  292  which extends to the proximal handle assembly. The proximal end  294  of the shaft  218  is preferably formed into an enlarged section, i.e., a head  296 , or a separate, enlarged head may be attached to the proximal end of the shaft. A swivel tube  298 , preferably made of a malleable alloy, such as brass or stainless steel, is provided over the head  296 . A distal end  299  of the swivel tube  298  is swaged or crimped to form a loose fit on the shaft  218 , while being small enough to retain the head  296 . The swivel tube  298  is placed onto the shaft  218  such that the head  296  is trapped inside the non-crimped portion  300  of the swivel tube  298 . The extension shaft  292  is pushed into the proximal open end  304  of the swivel tube  298 , and the swivel tube  298  is firmly crimped onto the extension shaft  292 . The extension shaft  292  is preferably made of either a flexible cable, for example, a 1×7 stranded stainless steel cable preferably of 0.032 inch diameter, or a solid wire of a springy material such as stainless steel, for example, a 0.020 inch diameter  304  stainless steel spring-temper wire. The extension shaft  292  extends proximally from the swivel tube  298  to the spool so that it transmits reciprocating longitudinal motion of the spool through the swivel tube  298  to the shaft  218 .  
         [0036]     This variation in construction of the extension shaft  292  is allowed because the purpose of the extension of the shaft  218  is merely to transmit the reciprocating axial motion imparted by the proximal handle; thus, if there exists a freely rotational joint between distal shaft  218  and the extension shaft  292 , there is no requirement for the extension shaft to be straight, torsionally-stiff, or camber-free.  
         [0037]     Turning now to  FIG. 10 , according to a fourth embodiment of the invention, the distal handle assembly  326  includes a mount  350  capable of firmly coupling the distal handle assembly  326  to a port in an endoscope handle (not shown), for example, by interference fit. In a preferred configuration, the mount  350  includes a coupling fitting  352  which is couplable to the port of the endoscope, and a connector  354  which is slidably movable, yet capable of being secured in a position, relative to the coupling fitting  352 . The connector  354  has a proximal end  356  which is threadably coupled to the distal end  336  of the body  330 .  
         [0038]     The coupling fitting  352  includes a cylindrical block  358  having an axial bore  360 , and a tubular nosepiece  362  secured in the axial bore  360 . The connector  354  includes a stepped bore  364  having a relatively large central portion  366 , and relatively smaller proximal and distal portions  368 ,  370 . The central portion  366  of the stepped bore  364  is sized to permit relative axial movement over the block  358 . The distal portion  370  of stepped bore  364  is sufficiently large to permit axial movement of the connector  354  over the nosepiece  362 . A locking screw  372  extends radially into the central portion  366  of the stepped bore  364  of the connector  354  such that the screw  372  may be rotated to tighten against the block  358  to lock the connector  354  axially relative to the block. The proximal end  314  of the sheath  312  extends through the nosepiece  362  and block  358  and is fixedly coupled in the proximal portion  368  of the stepped bore  364 . Other aspects of the fourth embodiment are substantially as described above with respect to the first embodiment.  
         [0039]     In use, the snare instrument is inserted through a port of an endoscope until the nosepiece  362  of the snare instrument is stably inserted in the port. The distal end of the sheath of the snare instrument may then be adjustably fixed relative the distal end of the endoscope by adjusting the connector  354  (and hence the handle  326 , shaft  318 , and sheath  312 ) over the block  358 . When the sheath is correctly positioned, screw  372  may be set. The distal handle  326  may then be operated, as described with respect to the first embodiment, to rotate the shaft  318  and snare relative to the sheath  312 . Likewise, a proximal handle assembly, as described with respect to the first embodiment, may then be manipulated to longitudinally move the shaft  318  to open and close the snare (the sheath having been previously set in position). With the above described embodiment, it may be possible for the physician to operate without an assistant as the axial placement of the snare instrument is established and set prior to rotation and activation of the snare loop.  
         [0040]     Referring now to  FIG. 11 , according to a fifth embodiment of the invention, a single handle assembly  427  capable of being fixed relative to an endoscope handle is provided. The handle assembly  427  of the snare instrument includes all of the controls previously provided in the proximal and distal handle assemblies, and is substantially similar to the distal handle assembly  326 , described above, with the additional incorporation of the snare opening and closing functions. To that effect, a sliding spool assembly  428  for longitudinally moving the shaft  418  relative to the sheath  412  may be substantially rigidly fixed to the proximal end  438  of the body  430 . For example, a distal end  462  of a stationary member  450  of the spool assembly  428  may be threadably mated with the proximal end  438  of the body  430 . The spool assembly is preferably otherwise substantially as described with respect to proximal handle assembly  28  of the first embodiment of the invention.  
         [0041]     The resulting device is fixedly couplable relative to an endoscopic handle and provides to the physician the following controls: a means for controllably advancing, retracting, and setting the sheath of the snare instrument relative to the distal end of the endoscope; a means for advancing (opening) and retracting (closing) the snare relative to the distal end of the sheath; and a means for steering (rotating) the snare to position the snare over a polyp. Since the physician has direct and immediate control of the entire instrument, the snare instrument obviates the need for an assistant during the procedure, and improves the speed and efficiency of the procedure.  
         [0042]     There have been described and illustrated herein several embodiments of a surgical snare instrument. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while the use of a particular monolithic and composite shafts have been disclosed with respect to a snare instrument, it will be appreciated that other flexible shafts may also be provided. Also, while the cautery connector has been shown on the proximal handle, it will be appreciated that the cautery connection may be provided in the physician&#39;s handle, or elsewhere along the length of the device, provided that the cautery connection will not interfere with the axial longitudinal and rotating motions of the shaft. Furthermore, while particular shapes and configurations have been described with respect to the proximal and distal handles, it will be appreciated that other shapes and configurations may be provided therefor. As such, it will also be appreciated that other configurations which provide a gripping handle for the sheath, means for rotating the shaft, and means for longitudinally moving the shaft may be used. For example, a control knob which rotates about an axis perpendicular to the axis of the shaft via a right-angle drive (using two meshing bevel gears) may be used to rotate the shaft. The gears may be configured to permit step-up or step-down rotation, for example, such that rotation of the shaft rotates the shaft twice as much or one-half as much. In addition, levers, gears, friction wheels, pulleys, links, etc., may be used to longitudinally move the shaft within the sheath, and the snare relative to the distal end of the sheath. Moreover, while a particular nosepiece has been described for use in the fourth and fifth embodiment, it will be appreciated that other nosepieces enabling stable coupling of the snare handle to an endoscope handle may be used. For example, a threaded connector capable of threading into or over a port on the endoscope handle may be used. Also, in the fourth and fifth embodiment, the mount and the body may be integrally formed or molded, and in the fifth embodiment, the body and the proximal sliding spool assembly may be integrally formed or molded. In addition, it will be appreciated that aspects of the various embodiments may be combined. For example, but not by way of limitation, the key of the second embodiment or the swivel joint of the third embodiment may be used in either of the fourth and fifth embodiments. Furthermore, the described handle assemblies may be used with other surgical instruments where both axial and rotational movement of a control member relative to a tubular member is required. For example, the handle may be used in laparoscopic and endoscopic instruments, generally, which include an end effector other than a snare loop. For example, and not by way of limitation, end effectors such as baskets and forceps may be used with the handle. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.