Patent Publication Number: US-2017348017-A1

Title: Open loop polypectomy system

Description:
This application claims the benefit as a continuation-in-part of U.S. patent application Ser. No. 14/370,617, filed Jul. 3, 2014, for ENDOSCOPIC SNARE DEVICE, which is a 371 of international application serial no. PCTUS1320457, filed Jan. 7, 2013, for ENDOSCOPIC SNARE DEVICE, which in turn claims the benefit of U.S. provisional patent application Ser. No. 61/648,312, filed May 17, 2012, for ENDOSCOPIC SNARE DEVICE, and U.S. provisional patent application Ser. No. 61/583,785, filed Jan. 6, 2012, for POLYPECTOMY SNARE DEVICE, all of which are incorporated herein by reference. This application also claims the benefit of U.S. provisional patent application Ser. No. 62/377,743, filed Aug. 22, 2016, for OPEN LOOP POLYPECTOMY SYSTEM, incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     Embodiments of this invention relate to endoscopic and laparoscopic surgical instruments. More specifically, embodiments of this invention relate to an open loop polypectomy system including a means for securely closing the loop. In some embodiments, the open loop polypectomy system comprises a snare wire and a capture mechanism wherein, when the snare wire is advanced, the snare wire extends from a distal portion of the open loop polypectomy system along a path passing through the capture mechanism. After the snare wire has advanced through the plane of the capture mechanism, retraction of the capture mechanism secures the snare wire, creating a formed loop around a target tissue. Retraction of at least one of the snare wire and capture mechanism contracts the formed loop, resecting the target tissue. 
     BACKGROUND OF THE INVENTION 
     Polyps are routinely found in the mucosal lining of colons and rectums of adults over the age of 50 years. In addition to the colon and rectum, polyps can develop in the mucosal lining of other hollow organs and cavities in the body, including the small intestine, ear, nose, sinuses, bronchi, stomach, and uterus. Removal of colon polyps has been strongly associated with a reduction in the incidence of colorectal cancer. 
     Polyps can be removed by surgical and endoscopic methods. Many polyps are routinely removed by biopsy forceps or closed loop endoscopic snares followed by cauterization or the application of a ligature. Snare polypectomy with cutting electrosurgical currents is a well-regarded currently available method for complete polyp removal. Polypectomy snares are monofilament, braided or coiled wire snares shaped into a closed loop at the end of an endoscopic tool. Snares are typically categorized as mini (&lt;11 mm diameter) or standard (15 mm-45 mm diameter). Snare geometries also vary widely and closed loop snares include oval, hexagonal, crescent, and circular-shaped loops. 
     Certain types of polyps can be difficult to remove. Difficult polyps include large pedunculated polyps with thick pedicles and/or large heads as well as sessile polyps (i.e. large, flat polyps) that have little to no stalk. Polyps may also be difficult to remove due to their location or multiple polyps clustering together. These difficult polyps present challenges to the clinician using existing snare technology. 
     The endoscopic treatment of difficult polyps presents unique challenges to the safety and efficacy of polypectomies. Encircling the stalk, or elongated pedicle, of a large polyp is often difficult with existing closed loop snares as the size of the polyp head inhibits the seating of the snare&#39;s loop around the stalk of the polyp which in turn prevents the typically necessary step of cauterization used to facilitate removal of the polyp. Sessile polyps often require the creation of a saline pillow beneath the polyp by using a submucosal saline injection technique to separate the tissue layers of the colon wall to reduce the chance of removal causing thermal injury or perforation of the colon wall. 
     Snare polypectomy is made more difficult when polyps are located in the right colon and cecum, behind folds, flexures and turns, or when polyps present themselves in an arrangement which creates access complications relative to the path of the endoscopic snare. Proper alignment can be particularly difficult to obtain when resecting a polyp from the medial wall of the cecum, just proximal to the ileocecal valve or at a flexure, or bend, of the colon. Polyp resection in the cecum and ascending colon are especially problematic due to the thinness of the colon wall which increases the risk of perforation or transmural burn. 
     Clinicians have dealt with complicated polypectomies in a number of ways. Difficult polyps are often removed piecemeal, sometimes over several procedures. The removal of colorectal polyps in this manner increases the risk to the patient, adds to the backlog of procedures scheduled for surgical suites, and unnecessarily consumes the valuable time of the clinician and support staff. Large pedunculated polyps located in sharp sigmoid bends can also be difficult and require individualized approaches, especially when utilizing conventional closed loop polypectomy snares. 
     SUMMARY 
     The disclosed open loop polypectomy system is an open loop snare device with a capture mechanism to secure an extended snare wire, thereby forming a loop. The diameter of the formed loop may then be decreased, resecting tissue surrounded by the formed loop. The loop used to resect tissue is controllably formed by the user at a desired location in contrast to existing closed loop snares, wherein closed loops must be maneuvered over and around obstacles to reach the desired location. 
     In some embodiments, the invention comprises an open loop polypectomy system including a snare wire and a capture mechanism, wherein, when the snare wire is advanced, the snare wire extends from a distal portion of the system along a path passing through the capture mechanism, wherein, after the snare wire is advanced at least to the capture mechanism, activation of the capture mechanism captures the snare wire, creating a formed loop, and wherein retraction of at least one of the snare wire and capture mechanism contracts the formed loop. 
     In further embodiments, the invention comprises an open loop polypectomy system including a handle, an elongated flexible sheath including a distal end and a proximal end, the proximal end being attached to the handle, a snare wire extending from the distal end of the sheath, and a closed loop extending from the distal end of the sheath, wherein when the snare wire is advanced, the snare wire extends from the distal end through the closed loop, wherein, after the snare wire is advanced through the closed loop, retraction of the closed loop captures the snare wire, creating a formed loop, and wherein retraction of at least one of the snare wire and the capture mechanism contracts the formed loop. 
     This summary is provided to introduce a selection of the concepts that are described in further detail in the detailed description and drawings contained herein. This summary is not intended to identify any primary or essential features of the claimed subject matter. Some or all of the described features may be present in the corresponding independent or dependent claims, but should not be construed to be a limitation unless expressly recited in a particular claim. Each embodiment described herein is not necessarily intended to address every object described herein, and each embodiment does not necessarily include each feature described. Other forms, embodiments, objects, advantages, benefits, features, and aspects of the present invention will become apparent to one of skill in the art from the detailed description and drawings contained herein. Moreover, the various apparatuses and methods described in this summary section, as well as elsewhere in this application, can be expressed as a large number of different combinations and subcombinations. All such useful, novel, and inventive combinations and subcombinations are contemplated herein, it being recognized that the explicit expression of each of these combinations is unnecessary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention will be had upon reference to the following description in conjunction with the accompanying drawings. The drawings are described in greater detail as follows: 
         FIG. 1  depicts an embodiment of a first embodiment of an open loop polypectomy system. 
         FIG. 2  depicts a front view of a distal end of the first embodiment with an extended capture mechanism. 
         FIG. 3  depicts a side view of the distal end of the first embodiment shown in  FIG. 2 . 
         FIG. 4  depicts the side view of the distal portion of the first embodiment shown in  FIG. 3  with a snare wire partially extended. 
         FIG. 5  depicts the side view of the distal portion of the first embodiment shown in  FIG. 4  with the snare wire extended through the capture mechanism. 
         FIG. 6  depicts a flexible sheath of the first embodiment adjacent to a target object (a cylinder, serving as a proxy for a polyp stalk). 
         FIG. 7  depicts the first embodiment shown in  FIG. 6  with a capture mechanism extended from the sheath to partially encircle the target object. 
         FIG. 8  depicts the first embodiment shown in  FIG. 7  with a snare wire extended from the sheath to pass through the capture mechanism. 
         FIG. 9  depicts the first embodiment shown in  FIG. 8  with the capture mechanism partially retracted into the sheath, the capture mechanism and snare wire cooperatively forming a loop encircling the target object. 
         FIG. 10  depicts the first embodiment shown in  FIG. 9  with the snare wire partially retracted into the sheath, thereby tightening the formed loop around the target object. 
         FIG. 11  depicts the handle of the first embodiment. 
         FIG. 12  depicts a side view of the distal portion of a second embodiment of an open loop polypectomy system with a capture mechanism partially exposed. 
         FIG. 13  depicts a side view of the distal portion of the second embodiment with the capture mechanism further exposed and having two jaws in an open configuration. 
         FIG. 14  depicts a side view of the distal portion of the second embodiment with a snare wire deployed along an arcuate path and curling back toward the capture mechanism. 
         FIG. 15  depicts a side view of the distal portion of the second embodiment with the snare wire deployed along an arcuate path and curling back toward and through the open jaws of the capture mechanism. 
         FIG. 16  depicts a side view of the distal portion of the second embodiment with the snare wire deployed along an arcuate path captured by the closed jaws of the capture mechanism, with the capture mechanism being partially retracted. 
         FIG. 17  depicts a side view of the distal portion of the second embodiment with the snare wire being retracted. 
         FIG. 18  depicts a perspective view of the distal portion of the second embodiment with the snare wire capture mechanism partially exposed. 
         FIG. 19  depicts a perspective view of the distal portion of a third embodiment of an open loop polypectomy system. 
         FIG. 20  depicts a perspective view of the distal portion of the third embodiment with a capture mechanism extended, and with a snare wire deployed along an arcuate path and curling back toward the snare wire capture mechanism. 
         FIG. 21  depicts a perspective view of the distal portion of the third embodiment with the snare wire deployed along an arcuate path and curling back toward and through the closed loop of the capture mechanism. 
         FIG. 22  depicts a perspective view of the distal portion of the third embodiment with the snare wire deployed along an arcuate path and captured by the retraction of the capture mechanism. 
         FIG. 23  depicts a side view of the distal portion of a fourth embodiment of an open loop polypectomy system, with a snare wire deployed along an arcuate path and curling back toward and through the closed loop of a snare wire capture mechanism. 
         FIG. 24  depicts a top perspective view of the distal portion of the fourth embodiment. 
         FIG. 25  depicts a bottom perspective view of the distal portion of the fourth embodiment. 
         FIG. 26  depicts a rear perspective view of the head of the fourth embodiment of the snare device, with the snare wire and legs of the closed loop shown in cross section along lines  16 - 16  of  FIG. 23 . 
         FIG. 27  depicts a top view of the head of a fifth embodiment of an open loop polypectomy system. 
         FIG. 28  depicts a side view of the head of the fifth embodiment. 
         FIG. 29  depicts a bottom perspective view of the head of the fifth embodiment. 
         FIG. 30  depicts a rear view of the head of the fifth embodiment, with the sheath omitted for clarity. 
         FIG. 31  depicts a rear perspective view of the head of the fifth embodiment of the snare device, with the sheath omitted for clarity. 
         FIG. 32  depicts a side view of the distal portion of the fifth embodiment, with a snare wire deployed along an arcuate path and captured by a retracted closed loop capture mechanism. 
         FIG. 33  depicts a top view of the distal portion of the fifth embodiment. 
         FIG. 34  depicts a side view of the distal portion of the fifth embodiment, with the sheath shown in cross section along lines  24 - 24  of  FIG. 33 . 
         FIG. 35 (A-D) is a series perspective views sequentially showing steps of a method of using an open loop snare device. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to selected embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended; any alterations and further modifications of the described or illustrated embodiments, and any further applications of the principles of the invention as illustrated herein are contemplated as would normally occur to one skilled in the art to which the invention relates. At least one embodiment of the invention is shown in great detail, although it will be apparent to those skilled in the relevant art that some features or some combinations of features may not be shown for the sake of clarity. 
     Any reference to “invention” within this document is a reference to an embodiment of a family of inventions, with no single embodiment including features that are necessarily included in all embodiments, unless otherwise stated. Furthermore, although there may be references to “advantages” provided by some embodiments of the present invention, other embodiments may not include those same advantages, or may include different advantages. Any advantages described herein are not to be construed as limiting to any of the claims. 
     Specific quantities (spatial dimensions, dimensionless parameters, etc.) may be used explicitly or implicitly herein, such specific quantities are presented as examples only and are approximate values unless otherwise indicated. Discussions pertaining to specific compositions of matter, if present, are presented as examples only and do not limit the applicability of other compositions of matter, especially other compositions of matter with similar properties, unless otherwise indicated. 
       FIGS. 1-11  depict a first embodiment of an open loop polypectomy system  10 .  FIGS. 3-5  depict the stepwise progression of advancement of the snare wire in the first embodiment.  FIGS. 6-10  depict the stepwise progression of advancement, capture of a target object (a cylinder, serving as a proxy for a polyp stalk), and retraction. 
     The first embodiment of an open loop polypectomy system  10  includes a proximal portion  11  and a distal portion  13 . The open loop polypectomy system  10  is designed to ensnare polyps or other tissues in proximity to the distal portion  13  of the open loop polypectomy system  10  and to be controlled by a user manipulating the proximal portion  11 . The proximal portion  11  is designed to remain outside a patient and includes a means for controlling the distal portion  13 , such as, for example, a handle  15 . Attached to the handle  15  is an elongated flexible sheath  14 . The distal portion  13  of the open loop polypectomy system  10  includes the distal end  9  of the sheath  14 , and a snare wire  16  and a capture mechanism  18  extending from the distal end  9 . The distal portion  13  is designed to be inserted into a patient.  FIG. 1  displays the snare wire  16  and capture mechanism  18  cooperatively surrounding a cylindrical tube  4 , the tube  4  serving as a proxy for a polyp stalk. 
     The open loop polypectomy system  10  is adapted to be channeled to a desired position within a patient by passing the elongated flexible sheath  14  though a channel in an elongated flexible tube adapted for introduction into a patient, such as an endoscopic or laparoscopic tube containing an instrument insertion channel. The sheath  14  preferably has a smaller diameter than that of the instrument insertion channel through which the distal portion  13  is to be channeled such that the distal portion  13  may pass with relative ease through the length of an endoscopic tube, and exit through the distal end of the endoscopic or laparoscopic tube when inserted within a body cavity. In some embodiments, the sheath  14  may be channeled to a desired position within a patient without use of a separate endoscopic or laparoscopic tube. In the depicted first embodiment, the sheath  14  is an elongated, transparent plastic tube. In other embodiments, the sheath may be translucent or opaque, or may be formed of a different biocompatible substance. 
     The distal portion  13  of an embodiment of an open loop polypectomy system  10  is shown in  FIGS. 2-10 . In this embodiment, the sheath  14  terminates at a sheath distal end  9 . At least a portion of the snare wire  16  and at least a portion of the capture mechanism  18  reside within the sheath  14 . 
     The distal portion  13  can be rotated within the endoscope&#39;s instrument insertion channel by manipulating the proximal portion  12  to modify the position and orientation of the snare wire  16  and capture mechanism  18  relative to the target polyp or tissue. Furthermore, as described in further detail below, in some embodiments at least one of the snare wire  16  and capture mechanism  18  is independently rotatable with respect to the sheath  14  to facilitate orienting the snare wire  16  and capture mechanism to encircle a target polyp or tissue. 
     In the depicted first embodiment, the capture mechanism  18  is a curved closed loop  24  that can be controllably extended and retracted from the distal end  9  of the sheath  14 , enlarging and shrinking the diameter of the closed loop  24 . As most easily seen in  FIGS. 2 and 3 , the curved closed loop  24  is generally oval shaped when viewed from the front and shaped similar to a letter “C” when viewed from the side. In some embodiments, the closed loop  24  is made from a memory shape material such as a memory shape alloy, for example, nickel titanium, also known as nitinol, or a memory shape polymer configured to adopt the depicted curved closed loop shape. As the closed loop  24  is retracted into the sheath  14 , it collapses to fit within the relatively narrow opening of the sheath distal end  9 . As the closed loop  24  is advanced to extend outwards from the distal end  9 , the closed loop  24  returns to the depicted curved closed loop shape. As most easily seen in  FIG. 2 , in some embodiments, the closed loop  24  includes a notch  52  sized to receive the snare wire  16 . 
     Referring now to  FIGS. 3-5 , the snare wire  16  is advanced from the sheath  14  to pass through the closed loop  24 . At least one of the snare wire  16  and the closed loop  24  can be rotated to facilitate the snare wire  16  passing through the closed loop  24 . 
       FIGS. 6-10  depict the stepwise progression of advancement, capture of a target object  50  (a simple cylinder, serving as a proxy for a polyp stalk or other tissue), and retraction of the same embodiment of the open loop polypectomy system. As shown in  FIG. 6 , the sheath  14  is positioned in proximity to or adjacent to a target object  50 . As shown in  FIG. 7 , the curved closed loop  24  is advanced from the sheath  14  and oriented to partially encircle the target object  50 . As shown in  FIG. 8 , the snare wire  16  is advanced to extend past the target object  50  and pass through the closed loop  24 . As shown in  FIG. 9 , the capture mechanism  18  can be activated by retracting at least a portion of the closed loop  24  into the sheath  14 , capturing the snare wire  16  against the target object and creating a formed loop  32 . As shown in  FIG. 10 , at least a portion of the snare wire  16  is retracted into the sheath  14 , further tightening the formed loop  32  encircling the target object  50 . The snare wire  16  is received in and extends through the notch  52 . In the depicted embodiment, the snare wire  16  includes a distal bulb  30  to prevent the snare wire  16  from reversing back through the capture mechanism  18 , once captured. Preferably, the notch  52  is sized to pass the snare wire  16  and sized to prevent passage of the distal bulb  30  through the notch  52 . If advisable, the capture mechanism  18  may be re-extended to release the snare wire  16  and disassemble the formed loop  32 , thereby removing the risk of the formed loop  32  being “hung” on a polyp or other tissue. 
     In the event that the target object is a polyp, target object can be incised by further decreasing the diameter of the formed loop  32 , or by retraction of the open loop polypectomy system  10  along the path of the endoscope as the endoscope is withdrawn from the colon, or as the open loop polypectomy system  10  is retracted into the instrument insertion channel of the endoscope. 
     In certain embodiments, the capture mechanism  18  and snare wire  16  are controlled by control wires (not visible within the sheath) affixed to the capture mechanism  18  and snare wire  16 , passing through the sheath  14 , and extending to the proximal portion  11  of the open loop polypectomy system  10 , where the control wires may be manipulated by the user. For example, advancing the control wire attached to the snare wire  16  would extend the snare wire  16 , and withdrawing the same control wire would retract the snare wire  16  into the sheath  14 . Referring now to  FIG. 11 , in some embodiments, the handle  15  includes independent first and second control mechanisms  54 ,  56 . The first control mechanism  54  is mechanically connected to the snare wire  16  via a control wire extending through the sheath  14  and the second control mechanism  56  is mechanically connected to the capture mechanism  18  via a separate control wire extending through the sheath  14 . Manipulation of the first and second control mechanisms  54 ,  56  by the user allows the user to control the snare wire  16  and control mechanism  18 . In the depicted embodiment, sliding the first control mechanism  54  in the direction of the sheath  14  advances the snare wire  16  to extend from the sheath distal end  9 . Sliding the first control mechanism  54  in the opposite direction retracts the snare wire  16  into the sheath distal end  9 . In the depicted embodiment, advancing the second control mechanism  56  into the handle  15  advances the capture mechanism  18  to extend from the sheath distal end  9 . Retracting the second control mechanism  56  from the handle  15  retracts the capture mechanism  18  into the sheath distal end  9 . Rotating the second control mechanism  56  rotates the capture mechanism  18 . While the snare wire  16  is not rotatable in the depicted embodiment, additional embodiments are envisioned in which a first control mechanism is configured to retract, extend, and rotate the snare wire. In some embodiments, the control wires are omitted and the snare wire extends through the sheath to connect to the first control mechanism and the capture mechanism extends through the sheath to connect to the second control mechanism. 
     In some embodiments, the handle  15  includes an electrical input  58  for receiving electrical current, whereby the current is delivered to the formed loop  32  as described in further detail below. The snare wire  16 , capture mechanism  18 , and control wires are preferably formed of materials with low resistance to minimize heating of the snare wire, capture mechanism, and control wires when current is passed therethrough. In some embodiments, the snare wire, capture mechanism, and control wires are formed of stainless steel. In further embodiments, one or more of the snare wire, capture mechanism, and control wires are formed of stainless steel, a shape memory polymer, or a shape memory alloy, such as nickel titanium alloy, commonly referred to as nitinol. 
       FIGS. 12-17  depict the stepwise progression of advancement, capture, and retraction of a second embodiment of an open loop polypectomy system  210 .  FIG. 18  depicts an intermediate step between  FIGS. 13 and 14  at a different view to display additional components of the polypectomy system  210 . 
     The distal portion  113  of the second embodiment of an open loop polypectomy system  110  is shown in  FIGS. 12-18 . In this embodiment, the sheath  114  terminates at a sheath distal end  109 . A substantially cylindrical head  117  is inserted within the sheath  114  and terminates at a flat distal end  112  flush with the sheath distal end  109 . The head  117  includes at least one channel in which at least a portion of a snare wire  116  and at least a portion of a capture mechanism  118  reside. In some embodiments, the head  117  may include at least two channels, at least one retaining the capture mechanism  118  and at least one retaining the snare wire  116 . In embodiments incorporating a plurality of snare wires  116 , the polypectomy system  110  may include three or more channels, at least one for the capture mechanism  118  and at least one for each of the plurality of snare wires  116 . As shown in  FIG. 18 , the distal end  112  of the first embodiment of the polypectomy system  110  includes two channels: a snare wire channel  120  and a capture mechanism channel  122 . 
     The capture mechanism  118  is configured to capture the snare wire  116 . In the second embodiment depicted in  FIGS. 12-18 , the capture mechanism  118  is a pair of opposing jaws  124  that can be controllably opened and closed from the proximal end (not shown for this embodiment) of the open loop polypectomy system  110 . Activation of the capture mechanism  118 , that is, transitioning the jaws  124  from an open position to a closed position, captures the snare wire  116  when the snare wire  116  extends between the jaws  124 . 
     The distal portion  113  can be rotated within the endoscope&#39;s instrument insertion channel by manipulating the proximal portion (not shown in this embodiment) of the endoscope to modify the position and orientation of the snare wire  116  and capture mechanism  118  relative to the target polyp or tissue. In certain embodiments, the snare wire channel  120  is preferably slotted or otherwise non-circular, so that the snare wire  116  is maintained at a specific orientation and reliably extends from the snare wire channel  120  on a predetermined plane. In this first embodiment, as shown in  FIG. 18 , the snare wire channel  120  is substantially circular. 
     The snare wire  116  is made from a memory shape material such as a memory shape alloy, for example, nickel titanium, also known as nitinol, or a memory shape polymer. As it exits the snare wire channel  120 , as shown by  FIGS. 14-15 , the snare wire  116  is fashioned so as to preferably curl toward the capture mechanism  118  along a predetermined arcuate path to produce a snare of sufficient diameter to ensnare a target polyp or other tissue. The snare wire  116 , being made from a memory shape material and being configured to curl back upon a predetermined arcuate path of sufficient diameter, will curl around the stalk of the target polyp and will pass through the open jaws  124  of the capture mechanism  118 , as shown in  FIG. 15 , at which point the jaws  124  will transition from an open position to a closed position, as shown in  FIG. 16 . When in a closed position, jaw distal portions  126  fit flush or interlock, the jaws  124  thereby forming a snare wire capture orifice  128  surrounding the snare wire  116 . The diameter of the snare wire capture orifice  128  is larger than the diameter of the snare wire  116 . In this first embodiment, the snare wire includes a distal bulb  130  with a diameter larger than that of the snare wire capture orifice  128 , such that the distal bulb  130  cannot pass back through the snare wire capture orifice  128  once captured. The snare wire  116  and the capture mechanism  118 , when the jaws  124  are in the closed position capturing the distal bulb  130 , cooperatively create a formed loop  132 . The formed loop  132  is a closed loop formed when the capture mechanism  118  captures the snare wire  116 . 
     In some embodiments, the capture mechanism  118  is maintained at a predetermined orientation to aid capture of the snare wire  116 . In other embodiments, the capture mechanism  118  may be capable of rotating freely in the capture mechanism channel  122 . For example, in  FIG. 18 , the capture mechanism  118  is shown rotated approximately  180  degrees compared to its orientation in  FIGS. 12-17 . 
     In some embodiments, as shown in  FIGS. 13-15 , the jaws  124  of capture mechanism  118  are biased in an open position, and may be forced into a closed position by partially retracting them into the capture mechanism channel  122 , as shown in  FIGS. 16-17 , or by advancing an endoscopic tube over the jaws  124 . In other embodiments, not shown, the jaws  124  are hingedly attached at their proximal end. 
     In various embodiments, the diameter of the formed loop  132  may be decreased by at least one of: retracting at least a portion of the capture mechanism  118  into the capture mechanism channel  122  and retracting at least a portion of the snare wire  116  into the snare wire channel  120 . In some embodiments, as shown in  FIG. 17 , both the capture mechanism  118  and snare wire  116  may be retracted into their respective channels  120 ,  122  to decrease the diameter of the formed loop  132 . 
       FIGS. 19-22  depict the stepwise progression of advancement, capture, and retraction of a third embodiment of the open loop polypectomy system. The distal portion  213  of the third embodiment of an open loop polypectomy system  210  is shown in  FIGS. 19-22 . In this embodiment, the sheath  214  terminates at a sheath distal end  209 . The substantially cylindrical head  217  is inserted within the sheath  214  and terminates at a flat distal end  212  flush with the sheath distal end  209 . The head  217  includes at least one channel in which at least a portion of a snare wire  216  and a capture mechanism  218  reside. In this third embodiment, the head  217  includes at least two channels: a snare wire channel  220  and a capture mechanism channel  222 . 
     The capture mechanism  218  of the third embodiment is a closed loop  224  that can be controllably extended and retracted from the distal end  212  of the head  217 , enlarging and shrinking the diameter of the closed loop  224 . The capture mechanism  218  is extended through the polypectomy system  210  via a capture mechanism channel  222 . In this third embodiment, as shown in  FIGS. 19-22 , the capture mechanism channel  222  is generally rectangular or otherwise non-circular in shape, so that the capture mechanism  218  is maintained at a specific orientation and reliably extends from the capture mechanism channel  222  on a predetermined plane. In further embodiments, the capture mechanism channel  222  may be two separate channels, each containing a leg of the capture mechanism  218 . 
     The snare wire  216  is advanced through the head  217  via a snare wire channel  220 . The open loop polypectomy system  210  can be rotated within an endoscope&#39;s instrument insertion channel from the proximal end of the endoscope to modify the orientation of the snare wire  216  and capture mechanism  218  relative to a target polyp or tissue. In certain embodiments, the snare wire channel  220  is preferably slotted or otherwise non-circular, so that the snare wire  216  is maintained at a specific, predetermined orientation and reliably extends from the snare wire channel  220  on a predetermined plane. 
     The snare wire  216  is made from a memory shape material such as a memory shape alloy, for example, nickel titanium, or a memory shape polymer. As it exits the snare wire channel  220 , as shown by  FIGS. 19-22 , the snare wire  216  is fashioned so as to curl toward the capture mechanism  218  along a predetermined arcuate path to produce a snare of sufficient diameter to ensnare a target polyp or tissue. The snare wire  216 , being made from a memory shape material and being configured to curl back upon a predetermined arcuate path designed to curl around a target tissue and will pass through the extended closed loop  224 , as shown in  FIG. 21 . As shown in  FIG. 22 , the capture mechanism  218  can be activated by retracting at least a portion of the closed loop  224  into the capture mechanism channel  222 , capturing the snare wire  216  against the head  217  and creating a formed loop  232 . The snare wire  216  includes a distal bulb  230  to prevent the wire  216  from reversing back through the capture mechanism  218 , once captured. In some embodiments, the distal end  212  includes a recessed portion shaped to receive the distal bulb  130 . 
     The distal portion  313  of a fourth embodiment of an open loop polypectomy system  310  is shown in  FIGS. 23-26 . In this embodiment, the head  317  is generally cylindrical in shape, terminating in a rounded distal end  312 . In this third embodiment, the polypectomy system  310  possesses a snare channel  320  located at the bottom of the head  317  and a pair of capture mechanism channels  321 ,  322  located at the top of the head  317 . The polypectomy system  310  may be freely rotated, so the description of channels or other features at the “top” or “bottom” of the head  317  only describes their positions relative to each other in the referenced drawings, and does not limit the orientation of the polypectomy system  310  as a whole. 
     The capture mechanism  318  of the fourth embodiment is a closed loop  324  that can be controllably extended and retracted from the distal portion  312  of the polypectomy system  310 , enlarging and shrinking the closed loop  324 . At least a portion of each leg  323 ,  325  of the closed loop  324  extends through the head  317  via a separate capture mechanism channel  321 ,  322 . By using two separate capture mechanism channels  321 ,  322 , the closed loop  324  is maintained at a specific orientation and reliably extends from the channels  321 ,  322  on a predetermined plane. The closed loop  324  may be extended or retracted by extending or retracting either leg  323 ,  325  of the closed loop  324  individually or both legs  323 ,  325  of the loop in combination. In some embodiments, one of the legs  323 ,  325  of the closed loop  324  may be fixed to the head  317  such that only the other, non-fixed leg may be extended or retracted. In this third embodiment, neither leg  323 ,  325  is fixed to the head  317 . 
     The snare wire  316  is advanced through the polypectomy system  310  via a snare wire channel  320 . In this embodiment, as best shown in  FIG. 26 , the snare wire  316  is a flattened, substantially rectangular shape, at least a portion of which resides in a substantially rectangular snare wire channel  320 . The snare wire  316  is unable to rotate within the snare wire channel  320 , thus maintaining the snare wire  316  at a predetermined orientation. 
     In this fourth embodiment, the distal portion  313  includes a slot  334  extending from the snare wire channel  320 , over the distal end  312 , in the direction of the capture mechanism  318 . The slot  334  is sized to accept the snare wire  316  such that the snare wire  316 , when retracted after being captured by the capture mechanism  318 , enters into the slot  334  and is thereby maintained at a specific orientation. 
     The snare wire  316  is made from a memory shape material such as a memory shape alloy, for example, nickel titanium, or a memory shape polymer. As it exits the snare wire channel  320 , as shown by  FIGS. 23-26 , the snare wire  316  is fashioned so as to curl toward the capture mechanism  318  along a predetermined arcuate path to produce a snare of sufficient diameter to ensnare a target polyp or tissue. The snare wire  316 , being made from a memory shape material and being configured to curl back upon a predetermined arcuate path of sufficient diameter, will curl around the stalk of the target polyp and will pass through the extended capture mechanism  318 . The capture mechanism  318  can then be activated by retracting at least a portion of the closed loop  324  into at least one of the capture mechanism channels  321 ,  322 , decreasing the diameter of the closed loop  324  and capturing the snare wire  316  against the head  317 , thereby creating a formed loop (not shown for this embodiment). The snare wire  316  includes a distal hook  330  to catch the closed loop  324  and prevent the wire  316  from reversing back through the capture mechanism  318 , once captured. In this embodiment, the head  317  includes a recessed portion  336  shaped to receive the distal hook  330 , once captured. 
     The head  317  is adapted to contact the distal end of the sheath (not shown). Unlike the head  117 ,  217  in the second and third embodiments, the head  317  in the fourth embodiment is shaped to fit over the distal end of the sheath. As shown in  FIG. 26 , the head  317  includes a cavity  340  sized to accept the distal end of the sheath. In various embodiments, the head may be adapted for at least a portion of the head to be inserted into the distal end of the sheath, for the distal end of the sheath to be inserted into the head, to abut the distal end of the sheath, or otherwise contact and be secured to the distal end of the sheath. 
     The distal portion  413  of a fifth embodiment of an open loop polypectomy system  410  is shown in  FIGS. 27-34 , with  FIGS. 27-31  focusing on the head  417 . In this embodiment, the head  417  is generally cylindrical in shape, terminating in a rounded distal end  412  and having a decreased diameter at its proximal end  440  to aid insertion of the proximal end  440  of the head  417  into the sheath  414 , as shown in  FIG. 34 , contacting the sheath distal end  409 . In this fifth embodiment, the polypectomy system  410  possesses a snare wire channel  420  located at the bottom of the head  417  and a pair of capture mechanism channels  421 ,  422  located at the top of the distal portion  413 , within a recessed portion  436 . The polypectomy system  410  may be freely rotated, so the description of channels or other features at the “top” or “bottom” of the head  417  only describes their positions relative to each other in the referenced drawings, and does not limit the orientation of the polypectomy system  410  as a whole. 
     As shown in  FIGS. 29 and 30 , the snare wire channel  420  has a round exit but the interior of the channel  420  is substantially rectangular in shape. In this fifth embodiment, the substantially rectangular interior of the snare wire channel  420  maintains the snare wire  416  at a specific orientation, as the wire  416  cannot rotate within the channel  420 . 
     The capture mechanism  418  of the fifth embodiment is a closed loop  424  that can be controllably extended and retracted from the distal portion  412  of the polypectomy system  410 , enlarging and shrinking the closed loop  424 . Each leg  423 ,  425  of the closed loop  424  is extended through the polypectomy system  410  via a separate capture mechanism channel  421 ,  422 . By using two separate capture mechanism channels  421 ,  422 , the closed loop  424  is maintained at a specific orientation and reliably extends from the channels  421 ,  422  on a predetermined plane. As shown in  FIG. 31 , in this fifth embodiment, leg  423  of the closed loop  424  is fixed to the head  417  such that only the other, non-fixed leg  425  may be extended or retracted. In this fourth embodiment, the fixed leg  423  terminates in a bulb  439  with a diameter greater than the diameter of the capture mechanism channel  421 . The capture mechanism  418  is thereby formed by single wire extending from the bulb  439 , through the capture mechanism channel  421 , out of the head  417  to form the closed loop  424 , returning through the capture mechanism channel  422 , and extending proximally down the sheath  414 . In other embodiments, other means for fixing a leg to the head may be used. 
     The snare wire  416  is advanced through the polypectomy system  410  via a snare wire channel  420 . In this embodiment, the distal portion  413  includes a slot  434  extending from the snare wire channel  420 , over the distal end  412 , in the direction of the capture mechanism  418 . The slot  434  is sized to accept the snare wire  416  such that the snare wire  416 , when retracted after being captured by the capture mechanism  418 , enters into the slot  434  and is thereby maintained at a specific orientation. 
     The snare wire  416  is made from a memory shape material such as a memory shape alloy, for example, nickel titanium, or a memory shape polymer. As in other embodiments, the snare wire  416  is fashioned so as to curl toward the capture mechanism  418  along a predetermined arcuate path to produce a snare of sufficient diameter to ensnare a target polyp or tissue and pass through the extended capture mechanism  418 . The capture mechanism  418  can then be retracted into the capture mechanism channels  421 ,  422 , capturing the snare wire  416  and creating a formed loop  432 . The snare wire  416  includes a distal bulb  430  to prevent the wire  416  from reversing back through the capture mechanism  418 , once captured. In this embodiment, the distal portion  412  includes a recessed portion  436  shaped to receive the distal bulb  430 . As shown in  FIGS. 32 and 33 , once the snare wire  416  is captured, retracting the capture mechanism  418  secures the distal bulb  430  in the recessed portion  436 . 
     Referring now  FIG. 35 (A-D), when the disclosed open loop polypectomy system  510  is used in a polypectomy procedure, the snare wire  516  may be extended to surround a polyp stalk  550  (panels A-B), then the distal bulb  530  be captured by the capture mechanism  518 , forming the formed loop  532  around the polyp stalk  550  (panel C). The polyp stalk  550  can be incised across the width of the stalk by decreasing the diameter of the formed loop  532 , or by retraction of the polypectomy system  510  of the along the path of the endoscope as the endoscope is withdrawn from the colon, or as the polypectomy system  510  is retracted into the instrument insertion channel of the endoscope (panel D). 
     Optionally, the formed loop  32 ,  132 ,  232 ,  332 ,  432 ,  532  created by the snare wire  16 ,  116 ,  216 ,  316 ,  416  and the capture mechanism  18 ,  118 ,  218 ,  318 ,  418 ,  518  completes a circuit across which current may be applied. This circuit will allow for the delivery of a bipolar current, which provides an integrated path for current return from the body to the current generator. This configuration may avoid the need for a grounding pad for bleeding current from the body, as is used with snares with a monopolar current configuration. The current may range from a level of amperes known by those skilled in the art to facilitate cutting up to a level of amperes known to those skilled in the art to facilitate coagulation and sealing of the wound created by the polyp removal. The known resistance of the snare wire facilitates the accurate calculation of the heat generated by electrically charging the snare wire. In one embodiment, the formed loop  32 ,  132 ,  232 ,  332 ,  432 ,  532  is a means for biopolar current delivery in which electrical current travels from the snare wire  16 ,  116 ,  216 ,  316 ,  416 ,  516  to the capture mechanism  18 ,  118 ,  218 ,  318 ,  418 ,  518 . 
     After incision of a polyp stalk, the bleeding polyp stalk remnant is preferably sealed to prevent bleeding. In one embodiment, the stalk remnant can be cauterized by the application of sufficient electric current through the snare wire  16 ,  116 ,  216 ,  316 ,  416 ,  516  or the capture mechanism  18 ,  118 ,  218 ,  318 ,  418 ,  518 . In a further embodiment, the stalk remnant is sealed by application of a ligature. In a still further embodiment the stalk remnant is sealed both by application of a ligature and by cauterization by the charged snare wire  16 ,  116 ,  216 ,  316 ,  416 ,  516  or the capture mechanism  18 ,  118 ,  218 ,  318 ,  418 ,  518 . 
     Further embodiments (not shown) incorporate a first magnet on the distal end of the snare wire and a second a magnet or an electromagnet on the capture mechanism or the head to facilitate the capture of the snare wire, or alternatively, to guide the snare wire to the capture mechanism. In these embodiments, the first magnet may act as a complement to or a replacement for the distal bulb or distal hook. In these embodiments, the second magnet may be positioned to attract and secure the first magnet, when the snare wire has been captured. 
     The open loop polypectomy system disclosed herein is adapted to be channeled to a desired position within a patient by passing the snare device though a channel in an elongated flexible tube adapted for introduction into a patient, such as an endoscopic tube containing an instrument insertion channel. In some embodiments, the polypectomy system may be used in conjunction with at least one additional endoscopic device. For example, an endoscopic tube may include two instrument insertion channels, one for the polypectomy system disclosed herein and the other for an endoscopic camera. In some embodiments, the camera may be used to detect cancerous masses or other target tissue and the polypectomy system used to remove the identified masses during a single colonoscopy procedure. By viewing the environment local to the distal end of the polypectomy system using the camera, the user may watch the progress of the snare wire and manipulate the polypectomy system so as to capture the snare wire using the capture mechanism when the snare wire is in the desired position. 
     The disclosed first, third, fourth and fifth embodiments are capable of functioning as both open loop polypectomy systems, as described above, and as closed loop polypectomy systems. When using the open loop polypectomy systems as closed loop polypectomy systems, the snare wire  16 ,  216 ,  316 ,  416  is not used and the curved closed loop  24 ,  224 ,  324 ,  424  may be used to capture polyps or other tissues using techniques known in the art. 
     Various aspects of different embodiments of the present disclosure are expressed in paragraphs X1, X2, X3 and X4 as follows: 
     X1. One embodiment of the present disclosure includes an open loop polypectomy system comprising: a snare wire; and a capture mechanism; wherein, when the snare wire is advanced, the snare wire extends from a distal portion of the system along a path passing through the capture mechanism; wherein, after the snare wire is advanced at least to the capture mechanism, activation of the capture mechanism captures the snare wire, creating a formed loop; and wherein retraction of at least one of the snare wire and capture mechanism contracts the formed loop. 
     X2. Another embodiment of the present disclosure includes an open loop polypectomy system comprising: a handle; an elongated flexible sheath including a distal end and a proximal end, the proximal end being attached to the handle; a snare wire extending from the distal end of the sheath; and a closed loop extending from the distal end of the sheath; wherein when the snare wire is advanced, the snare wire extends from the distal end through the closed loop; wherein, after the snare wire is advanced through the closed loop, retraction of the closed loop captures the snare wire, creating a formed loop; and wherein retraction of at least one of the snare wire and the capture mechanism contracts the formed loop. 
     X3. One embodiment of the present disclosure includes a snare device comprising: a snare wire; and a capture mechanism; wherein when the snare wire is advanced, the snare wire extends from a distal portion of the device along an arcuate path curving back toward the capture mechanism; wherein after the snare wire is advanced at least to the capture mechanism, activation of the capture mechanism captures the snare wire, creating a formed loop; and wherein retraction of at least one of the snare wire and capture mechanism contracts the formed loop. 
     X4. Another embodiment of the present disclosure includes a snare device comprising: a head including at least one channel; a snare wire, at least a portion of the snare wire residing in the at least one channel; and a closed loop, at least a portion of the closed loop residing in the at least one channel; wherein when the snare wire is advanced, the snare wire extends from the at least one channel along an arcuate path curving back toward the closed loop; wherein, after the snare wire is advanced through the closed loop, retraction of the closed loop the captures the snare wire, creating a formed loop; and wherein retraction of at least one of the snare wire and the capture mechanism contracts the formed loop. 
     Yet other embodiments include the features described in any of the previous paragraphs X1, X2, X3 or X4, as combined with one of more of the following aspects: 
     Wherein at least one of the snare wire and the capture mechanism is rotatable. 
     Wherein the capture mechanism includes opposing jaws. 
     Wherein the capture mechanism includes a closed loop. 
     Wherein the capture mechanism is a curved closed loop. 
     Wherein the head includes a recessed portion. 
     Wherein the snare wire includes one of a distal bulb and a distal hook. 
     Wherein the snare wire includes a distal bulb. 
     Wherein the closed loop includes a notch sized to pass the snare wire and sized to prevent passage of the distal bulb. 
     Wherein, after the snare wire is advanced through the closed loop, retraction of the closed loop captures the snare wire in the notch. 
     Wherein a diameter of the distal bulb is greater than a diameter of the snare wire. 
     Wherein the head includes a recessed portion shaped to receive one of a distal bulb and a distal hook. 
     Wherein activation of the capture mechanism comprises transitioning opposing jaws from an open position to a closed position. 
     Wherein activation of the capture mechanism comprises retraction of the closed loop. 
     Wherein the snare device includes a head contacting a distal end of a sheath. 
     Wherein the open loop polypectomy system includes a head contacting a distal end of a sheath. 
     Wherein the snare device includes a head at least partially inserting within the distal end of a sheath. 
     Wherein the head includes at least one snare wire channel and at least one capture mechanism channel. 
     Wherein the head includes one snare wire channel and one capture mechanism channel. 
     Wherein the head includes one snare wire channel and two capture mechanism channels. 
     Wherein the head includes a notch sized to receive said snare wire. 
     Wherein the snare wire and the capture mechanism both extend from a distal end of an elongated flexible sheath. 
     Wherein creation of said formed loop completes a circuit for delivery of electrical current. 
     Wherein the handle includes a first control mechanism mechanically connected to the snare wire through the sheath. 
     Wherein manipulation of the first control mechanism extends, retracts, or rotates the snare wire. 
     Wherein the handle includes a second control mechanism mechanically connected to the closed loop through the sheath. 
     Wherein manipulation of the second control mechanism extends, retracts, or rotates the closed loop. 
     The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom, for modifications can be made by those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention. 
     Reference systems, if used herein, refer generally to various directions (for example, top, bottom, upper, lower, forward, rearward, left, right, etc.), which are merely offered to assist the reader in understanding the various embodiments of the disclosure and are not to be interpreted as limiting. Other reference systems may be used to describe various embodiments. 
     While illustrated examples, representative embodiments and specific forms of the invention have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive or limiting. The description of particular features in one embodiment does not imply that those particular features are necessarily limited to that one embodiment. Features of one embodiment may be used in combination with features of other embodiments as would be understood by one of ordinary skill in the art, whether or not explicitly described as such. Exemplary embodiments have been shown and described, and all changes and modifications that come within the spirit of the invention are desired to be protected.