Patent Publication Number: US-11642115-B2

Title: System for a minimally-invasive, operative gastrointestinal treatment background

Description:
This application is a continuation of U.S. application Ser. No. 15/261,930, filed Sep. 10, 2016, which is a continuation in part of U.S. application Ser. No. 14/622,831, filed Feb. 14, 2015, now U.S. Pat. No. 10,595,711, which is a continuation in part of U.S. application Ser. No. 13/913,466, filed Jun. 9, 2013, now U.S. Pat. No. 9,186,131, which is a continuation in part of U.S. application Ser. No. 12/970,604, filed Dec. 16, 2010, now U.S. Pat. No. 8,506,479, which claims priority under 35 U.S.C. § 119 to U.S. Provisional Application Ser. No. 61/287,077, filed Dec. 16, 2009, and U.S. application Ser. No. 13/913,466, filed Jun. 9, 2013, now U.S. Pat. No. 9,186,131 is a continuation in part of U.S. application Ser. No. 13/531,477, filed Jun. 22, 2012, now U.S. Pat. No. 8,932,211. The entire contents of each of these applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This application is directed to endoscopic systems and methods for expanding body lumens and for treating tissue within the body lumen. 
     DESCRIPTION OF THE RELATED ART 
     Endoscopic procedures involving the gastrointestinal system offer advantages over conventional surgery in that they are less invasive and may provide visualization. 
     One current problem includes a lack of technology for an optimal minimally-invasive expansion of a stable, working space adjacent to the target tissues that could otherwise collapse around the target lesion or defect during an operative treatment. Having the ability to effectively expand and optimally reconfigure or reshape the working space could markedly facilitate an intra-luminal operation. A better expanded, stable and optimally configured working space allows the instruments and endoscope to be independently manipulated and properly visualized around the target tissue. 
     Another current problem includes a lack of an endoscopic technology for not only expanding, but also affixing and reshaping, both the target tissue and surrounding tissue. In a bowel, for example, such a stable operative space could include a space that is non or less collapsible, with limited peristalsis or aperistaltic, and/or affixed at a particular point in the abdominal cavity. The fixed point can be considered fixed in relation to, for example, a fixed body point in the patient, such as the patient&#39;s hip. Significant bowel movement is considered to be highly undesirable during an intra-luminal operation on the bowel, for example, since it may create a challenging, unstable operative environment. Such bowel movement is normal, of course, even in a sedated patient and can be caused, for example, by bowel collapse from an air leak, peristalsis, breathing, and movement of the scope and instruments. Having a technology to overcome this problem would help provide a stable operative space, which is clinically desired in the operative environment. 
     Another current problem includes a lack of an endoscopic technology for retracting the tissue dynamically, for example, through an adjustable tissue retraction structure allowing for a controlled degree of expansion or collapse of the structure, to further configure the working space as desired around the instruments and target tissue. Such control can effectively provide for a method of adjusting the retractor, as well as tissue placement, in-and-around the working space. By increasing and releasing the tension on the retractor, the amount of tissue to be placed in the working space, for example, can be better-gauged and controlled during a procedure. Moreover, the tissue retraction and, particularly, traction-contra-traction can be facilitated to help create a desired dissecting plane or position the tissue more optimally during an operation. Having a technology to overcome this problem would help create an operative environment that is more desirable for tissue dissection, retraction, cutting and a removal of tissue. 
     Another current problem includes a lack of an endoscopic technology for organizing the endoscope, instruments, and working space in a manner that can maximize the working space for the treatment. The larger working space can improve the ability to manipulate the instruments and endoscope in a minimally-invasive manner from outside the body. Namely, one of skill would like to have a working space that has a point of entry for the instruments that is as far as practical from the target tissue to provide additional flexibility in approaching and visualizing the target tissue, perhaps providing more operating room for selecting a trajectory of the instruments toward the target tissue that is, for example, at least substantially perpendicular to the plane of dissection of the target tissue. Having a technology to overcome this problem would provide the person of skill with a system and procedure that is more desirable for a removal of tissue. 
     In view of at least the above, one of skill in the art of endoscopic, gastrointestinal surgical treatments would appreciate the technology taught herein which provides one or more of (i) a minimally-invasive expansion of the intra-luminal working space; (ii) an affixing, particularly an affixing that includes a reconfiguring without stretching or reconfiguring with stretching, of both the target tissue and surrounding tissue to help provide a stable, operative space; (iii) a retracting of the tissue dynamically, allowing for a partial or complete expansion or collapse, to further configure the working space between the instruments and the target tissue; and (iv) an organization of the endoscope instruments, such as the retractor and tools to maximize the working space and maneuverability, allowing for a maximum flexibility in approaching and visualizing the target tissue. It should be appreciated that having such improvements would reduce the technical complexity, and increase the efficacy and safety of, otherwise complex endoscopic operations. Moreover, doing so at a low cost, while using an affordable system that is introduced in the subject atraumatically and in a manner that does not substantially disrupt the conventional colonoscopy workflow, would be seen by those of skill as a very substantial advancement in the field of endoscopic surgical procedures. 
     In endoscopic procedures, to enable non-traumatic advancement of the catheter through the anatomy to the target site, sufficient flexibility is necessary. However, sufficient stability is also necessary to limit flexing of the distal region of the catheter once at the target site where the expanded working space is created. It would be advantageous to provide a catheter that achieves an effective balance of these competing objectives. 
     SUMMARY 
     The teachings provided herein are generally directed to improved methods and devices for operatively treating gastrointestinal disorders endoscopically in a stable, yet dynamic operative environment, and in a minimally-invasive manner. The systems, for example, include an endoscopic surgical suite. The surgical suite can have a reversibly-expandable retractor that expands to provide a stable, operative environment within a subject. The expansion can be asymmetric around a stabilizer subsystem to maximize space for a tool and in some embodiments an endoscope to each be maneuvered independently to visualize a target tissue and treat the target tissue from outside the patient in a minimally invasive manner. Embodiments taught herein provide, among other improvements, an increase in distance between tool ports and the target tissue to improve maneuverability and triangulation of the tools with respect to the target tissue, as well as a larger field of view. 
     In some embodiments, floating channels are provided to increase the flexibility of the system as compared to the use of fixed channels. The floating channels receive flexible instrument guides which provide channels for working instruments. Alternatively, working instruments can be inserted directly into the floating channels. 
     In accordance with one aspect of the present invention, a system for performing minimally invasive procedures in a working space within a body lumen of a patient is provided comprising a flexible catheter configured to receive a working instrument therethrough, the flexible catheter having a proximal portion, a distal portion, and a working space expanding system positioned at the distal portion. The working space expanding system includes first and second flexible elements movable from a non-expanded insertion position to an expanded position forming an expanded region to expand the working space within the body. The first and second flexible elements are connected to a coupling structure at a distal region. An expandable stabilizing member is movable axially with respect to the coupling structure to stabilize the distal portion of the flexible catheter. 
     In some embodiments, a covering is positioned over the first and second flexible elements, the covering having an opening to receive body tissue. 
     In some embodiments, the stabilizing member is movable from a first position further from the coupling structure to a second position closer to the coupling structure. In some embodiments, in the second position the stabilizing member is positioned over the coupling structure; in other embodiments, in the second position the stabilizing member is positioned adjacent a distal end of the coupling structure. 
     In some embodiments, the stabilizing member is an inflatable balloon, and can have in some embodiments a donut-shape to form a gap to receive the coupling structure within the gap. In other embodiments, the stabilizing member includes a mesh-like structure. In other embodiments, the stabilizing member includes a stent-like structure. 
     In some embodiments, the stabilizing member is connected to a second catheter, the second catheter extending through a lumen in the flexible catheter. 
     The system can further include one or more flexible guides slidably positioned within the flexible catheter, wherein a distal portion of the flexible guides is movable to angled positions within the expanded region and the flexible guides are configured and dimensioned to receive an endoscopic working instrument therethrough. 
     In some embodiments, a bridge member extends transversely between the first and second flexible elements to increase stability. 
     In accordance with another aspect of the present invention, a system for performing minimally invasive procedures in a working space within a body lumen of a patient is provided comprising a flexible catheter configured to receive a working instrument therethrough, the flexible catheter having a proximal portion, a distal portion, and a working space expanding system positioned at the distal portion. The working space expanding system includes first and second flexible elements movable from a non-expanded insertion position to an expanded position forming an expanded region to expand the working space within the body. The first and second flexible elements are connected to a coupling structure at a distal region. An expandable stabilizing member is positioned over the coupling structure and movable from a non-expanded position to an expanded position to stabilize the distal portion of the flexible catheter. 
     In some embodiments, the stabilizing member includes a mesh-like structure. In other embodiments, the stabilizing member includes a stent-like structure. In other embodiments, the stabilizing member includes an inflatable balloon. 
     In some embodiments, the stabilizing member is connected to a second catheter, the second catheter extending through a lumen in the flexible catheter. 
     In accordance with another aspect of the present disclosure, a system for performing minimally invasive procedures in a working space within a body lumen of a patient is provided comprising a flexible catheter configured to receive a working instrument therethrough, the flexible catheter having a proximal portion, a distal portion and a working space expanding system positioned at the distal portion. The working space expanding system includes first and second flexible elements movable from a non-expanded insertion position to an expanded position forming an expanded region to expand the working space within the body. An expandable stabilizing member is positioned at the distal portion of the flexible catheter. The first and second flexible elements are connected to the stabilizing member, wherein the stabilizing member is expandable to expand from a low profile insertion position to an expanded position to stabilize the distal portion of the flexible catheter. 
     In some embodiments, the stabilizing member is an inflatable balloon. The stabilizing member can be axially fixed about the coupling structure and can be inflatable to move from a deflated insertion position to an inflated stabilizing position. In some embodiments, the inflatable balloon includes a rigid element supported therein and the first and second flexible elements are connected to the rigid element. 
     In some embodiments, the first flexible element has a lumen extending therethrough communicating with the stabilizing member for transport of fluid to inflate the stabilizing member. 
     In accordance with another aspect of the present disclosure, a method for performing a minimally invasive procedure in a body lumen of a patient is provided comprising: a) providing a flexible catheter having a working space expanding system and an expandable stabilizing member; b) providing a flexible endoscope to visualize target tissue; c) advancing the flexible catheter within the body lumen adjacent target tissue to be treated; d) visualizing target tissue with the flexible endoscope; e) expanding the working space expanding system from a non-expanded insertion position to an expanded position to increase the working space within the body lumen; and f) either before or after step (e), expanding the stabilizing member. 
     In some embodiments, the method further includes the step of retracting the stabilizing member closer to the working space expanding system. The step of retracting can occur prior to or after the step of expanding the working space expanding system. The step of retracting can occur prior to or after expanding the stabilizing member. 
     In some embodiments, the step of expanding the stabilizing member includes the step of inflating the expandable member. In other embodiments, the step of expanding the stabilizing member includes the step of expanding a mechanical structure. 
     In some embodiments, the working space expanding system includes first and second flexible elements, the first and second flexible elements connected at a distal end by a coupler. In some embodiments the step of retracting the stabilizing member moves the stabilizing member to a position overlying the coupler and in other embodiments the step of retracting the stabilizing member moves the stabilizing member to a position adjacent a distal end of the coupler. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG.  1    illustrates a system for operatively treating gastrointestinal disorders endoscopically in a stable, yet dynamic operative environment, and in a minimally-invasive manner, according to some embodiments. 
         FIGS.  2 A and  2 B  illustrate how a system as taught herein can be positioned for treating a lesion in the ascending colon, according to some alternate embodiments. 
         FIGS.  3 A- 3 L  illustrate how a system as taught herein can be used in removing a lesion in a colon, according to some embodiments, the colon shown in a cutaway view to show the system in perspective, wherein  FIG.  3 A  illustrates the system being inserted into the colon and having a sheath covering the retractor,  FIG.  3 B  illustrates the retractor in the non-expanded position,  FIG.  3 C  illustrates the retractor in the expanded position to create an asymmetric working space and further showing the endoscope in an articulated position,  FIG.  3 D  is a view similar to  FIG.  3 C  showing two endoscopic instruments extending from respective tool channels,  FIG.  3 E  illustrates the tool channels and the endoscopic instruments bent toward the target lesion,  FIG.  3 F  illustrates the lesion being removed from the wall of the colon by the endoscopic instruments,  FIG.  3 G  illustrates the lesion removed from the wall of the colon and positioned within the retractor,  FIG.  3 H  illustrates endoscopic instruments extending from the tool channels and bent toward the colon wall to repair the defect in the colon wall resulting from removal of the lesion,  FIG.  3 I  illustrates placement of clamps to close the tissue defect in the colon wall,  FIG.  3 J  illustrates the retractor in the collapsed position to capture the lesion for removal from the colon;  FIG.  3 K  illustrates the retractor encapsulated within the sheath for removal from the colon, and  FIG.  3 L  illustrates the closed tissue defect after completion of the surgical procedure. 
         FIGS.  4 A- 4 E  illustrate details of a system as taught herein, in side, axial, and oblique views of expanded and collapsed configurations, and including a stabilizer subsystem, according to some alternate embodiments, wherein  FIG.  4 A  is a side view of the system with the retractor in the non-expanded (collapsed) position,  FIG.  4 B  is an axial view of the system with the retractor in the non-expanded position,  FIG.  4 C  is an axial view of the system with the retractor in the expanded position,  FIG.  4 D  is a perspective view of the system in the position of  FIG.  4 A , and  FIG.  4 E  is a view similar to  FIG.  4 D  showing the retractor in the expanded position. 
         FIGS.  5 A- 5 D  illustrate side and top views of a system as taught herein, having side views and top views of expanded and collapsed configurations, according to some alternate embodiments, wherein  FIG.  5 A  is a side view of the system with the retractor in the non-expanded (collapsed) position,  FIG.  5 B  is a side view similar to  FIG.  5 A  showing the retractor in the expanded position;  FIG.  5 C  is a top view of the system with the retractor in the non-expanded position of  FIG.  5 A , and  FIG.  5 D  is a top view of the system with the retractor in the expanded position of  FIG.  5 B . 
         FIGS.  6 A- 6 D  illustrate side views of a system as taught herein, having side views and cross-sections of expanded and collapsed configurations of the system, according to some other alternate embodiments, wherein  FIG.  6 A  is a side view of the system with the retractor in a non-expanded (collapsed) position;  FIG.  6 B  is a side view similar to  FIG.  6 A  with a housing half removed to show internal components of the system,  FIG.  6 C  is a side view similar to  FIG.  6 A  showing the retractor in an expanded position, and  FIG.  6 D  is a side view similar to  FIG.  6 B  showing the retractor in the expanded position. 
         FIG.  7    illustrates a cutaway view of the distal end of the outer tube of a system as taught herein, showing components of the expansion and collapse of the retractor, according to some embodiments. 
         FIG.  8    illustrates the cutaway view of  FIG.  7   , showing the distal end of the outer tube of a system as taught herein, in which components of the system can be floating in the outer tube to enhance flexibility for positioning the system in a subject, according to some embodiments. 
         FIGS.  9 A and  9 B  illustrate side views of working, and/or floating, channels that can be used to guide tools as taught herein, according to some embodiments. 
         FIGS.  10 A- 10 E  illustrate an alternate embodiment of the system wherein a retractor sheath covers a retractor of a system as taught herein, according to some embodiments, wherein  FIG.  10 A  is a top view of the system with the retractor in a non-expanded (collapsed) position,  FIG.  10 B  is a perspective view of the system in a non-expanded position,  FIG.  10 C  is a side view of the system with the retractor in a non-expanded position,  FIG.  10 D  is a top view of the system showing the retractor in an expanded position, and  FIG.  10 E  is a side view of the system showing the retractor in the expanded position. 
         FIG.  11    is a perspective view of an alternate embodiment of the system showing the catheter and two tool channels. 
         FIG.  12    is a perspective view of the catheter of  FIG.  11    being inserted over the proximal end of the endoscope of  FIG.  13    (prior to insertion of the endoscope into the colon), the retractor system shown in the collapsed position. 
         FIG.  13    illustrates insertion of the endoscope through the colon. 
         FIG.  14    is a perspective view showing the catheter of  FIG.  11    being further advanced over the endoscope of  FIG.  13   , the retractor system shown in the collapsed position. 
         FIG.  15    is a perspective view showing the catheter fully advanced over the endoscope to the desired position adjacent the target tissue, the retractor system shown in the collapsed (non-expandable) position. 
         FIG.  16    is a perspective view of the proximal end of the catheter of  FIG.  11   . 
         FIGS.  17 A and  17 B  are side views in partial cross-section showing movement of the actuator from a proximal position to a distal position to advance the rigidifying structure to stiffen the retractor system. 
         FIG.  17 C  is a perspective view similar to  FIG.  15    showing an alternate embodiment of the rigidifying structure. 
         FIG.  17 D  is a perspective view similar to  FIG.  17 C  showing the rigidifying structure of  FIG.  17 C  advanced over the flexible element. 
         FIG.  18    is a perspective view showing the two tool channels (guides) adjacent the proximal end of the catheter of  FIG.  11    for insertion therethrough. 
         FIG.  19 A  is a perspective view illustrating the tool channels inserted into the catheter of  FIG.  11    and  FIG.  19 B  is a perspective view illustrating an alternative embodiment of the tool channels. 
         FIGS.  20 A and  20 B  are side views in partial cross-section showing movement of the actuator from a proximal position to a distal position to move the retractor system to the expanded position. 
         FIG.  21 A  is a view similar to  FIG.  15    showing the retractor system in the expanded position and further illustrating the tool channels being advanced into the working space (chamber) created by the expansion of the retractor system. 
         FIG.  21 B  is a view similar to  FIG.  21 A  illustrating an alternate embodiment wherein the tool channels are advanced from the catheter prior to expansion of the retractor system. 
         FIG.  22    is a view similar to  FIG.  21 A  showing a first endoscopic instrument (tool) advanced from a first tool channel. 
         FIG.  23    is a view similar to  FIG.  22    showing a second endoscopic instrument (tool) advanced from a second tool channel. 
         FIG.  24    is a view similar to  FIG.  23    showing both endoscopic instruments further advanced from the tool channels. 
         FIG.  25    is a view similar to  FIG.  24    showing the endoscopic instruments further advanced from the tool channels to dissect the lesion on the colon wall. 
         FIG.  26    is a view similar to  FIG.  25    showing the lesion which has been removed from the colon wall by the dissecting instrument placed within the retractor system. 
         FIG.  27    is a perspective view of the proximal end of the catheter showing proximal movement of the actuator to return the retractor system to the collapsed position for removal from the colon. 
         FIG.  28    is a view similar to  FIG.  26    showing the retractor system in the collapsed position. 
         FIG.  29    is a view similar to  FIG.  28    showing the covering member closed to encapsulate the lesion for removal. 
         FIG.  30    is a front view of the system in the expanded position of the retractor system and showing two tool channels extending from the catheter. 
         FIGS.  31 A and  31 B  are cross-sectional views illustrating the switch for retaining the suture for closing the covering (bag). 
         FIG.  32    is a perspective view of the distal end of the outer tube (catheter) of an alternate embodiment of the system showing two floating channels therein. 
         FIG.  33    is a perspective view of a proximal portion of the system of  FIG.  32   . 
         FIG.  34    is a close up cutaway view showing one of the floating channels of  FIG.  32   . 
         FIG.  35 A  is a view similar to  FIG.  34    showing an alternate embodiment of the floating channel. 
         FIG.  35 B  is a view similar to  FIG.  35 A  showing the floating channel advancing within the fixed distal tube. 
         FIG.  35 C  is a view similar to  FIG.  35 B  showing movement of the floating channel beyond the fixed distal tube. 
         FIG.  36    is a front view of the system of  FIGS.  32  and  33    shown within the colon. 
         FIGS.  37 A and  37 B  are transverse cross-sectional views through the outer tube showing radial movement of an intermediate portion of the floating channels within the lumen of the outer tube. 
         FIG.  38    is a cross-sectional view illustrating bending of the outer tube and movement of the floating channels of  FIGS.  35 A- 35 C . 
         FIGS.  39 A and  39 B  are side perspective views of the distal portion of the system of  FIG.  38    showing the effect of bending of the outer tube and movement of the floating channels, and the retractor system shown in the non-expanded configuration. 
         FIG.  39 C  is a bottom perspective view of the retractor system of  FIG.  39 A . 
         FIG.  40    is a longitudinal cross-sectional view of an alternate embodiment of the system with the retractor system shown in the collapsed insertion position. 
         FIG.  41    is a bottom perspective view of the system of  FIG.  40    with the retractor system shown in the non-expanded configuration. 
         FIG.  42    is a side perspective view of the system of  FIG.  41   . 
         FIG.  43 A  is a bottom perspective view of another alternate embodiment of the system having two flexible elements and a balloon stabilizer, and showing the balloon in the distal non-expanded position. 
         FIG.  43 B  is a perspective view of a distal portion of the system of  FIG.  43 A  showing the balloon in the proximal non-expanded position; 
         FIG.  43 C  is a perspective view of the distal portion of the system of  FIG.  43 A  showing the balloon in the proximal expanded position adjacent the distal coupler and further showing the retractor system expanded within a patient&#39;s colon. 
         FIG.  43 D  is a view similar to  FIG.  43 B  showing a cover over the flexible elements. 
         FIG.  44 A  is a perspective view of another alternate embodiment of the system having a balloon stabilizer and showing a donut shaped balloon in the distal non-expanded position. 
         FIG.  44 B  is a perspective view of a distal portion of the system of  FIG.  44 A  showing the balloon in the expanded position distal of the distal coupler; 
         FIG.  44 C  is a perspective view similar to  FIG.  44 B  showing the expanded balloon overlying the distal coupler. 
         FIG.  45 A  is a perspective view of the distal portion of another embodiment of the system showing the donut shaped balloon in the non-expanded position overlying the distal coupler. 
         FIG.  45 B  is a perspective view similar to  FIG.  45 A  showing the donut shaped balloon in the expanded position over the distal coupler. 
         FIG.  46 A  is a perspective view of the distal portion of another alternate embodiment of the system showing the mesh structure in the non-expanded position within the catheter. 
         FIG.  46 B  is a perspective view similar to  FIG.  46 A  showing the catheter in the proximal position. 
         FIG.  46 C  is a perspective view similar to  FIG.  46 B  showing the mesh structure in the expanded position. 
         FIG.  47 A  is a perspective view of the distal portion of another alternate embodiment of the system showing the stent-like structure in the non-expanded position within the catheter. 
         FIG.  47 B  is a perspective view of the system of  FIG.  47 A  showing the catheter in the proximal position within a patient&#39;s colon. 
         FIG.  47 C  is a perspective view similar to  FIG.  47 A  showing the stent structure in the expanded position, and further showing the retractor system expanded within a patient&#39;s colon. 
         FIG.  48    is a perspective view of a distal portion of another alternate embodiment having four flexible elements for symmetric expansion and showing the balloon in the expanded position. 
         FIG.  49 A  is a perspective view of a distal portion of another alternate embodiment of the system showing the flexible elements attached directly to the balloon and the balloon in the non-expanded position. 
         FIG.  49 B  is a view similar to  FIG.  49 A  showing the balloon in the expanded position. 
     
    
    
     DETAILED DESCRIPTION 
     The teachings provided herein are generally directed to improved methods and devices for operatively treating gastrointestinal disorders endoscopically in a stable, yet dynamic operative environment, and in a minimally-invasive manner. The systems, for example, include an endoscopic surgical suite that is created by the systems disclosed herein. The surgical suite can have a reversibly-expandable retractor that expands to provide a stable, operative environment within a subject. In some embodiments, the expansion can be asymmetric around a stabilizer subsystem to maximize space for a tool and an endoscope to each be maneuvered independently to visualize a target tissue and treat the target tissue from outside the patient in a minimally invasive manner. Embodiments taught herein can provide, among other improvements, an increase in distance between tool ports and the target tissue to enhance the independent maneuverability and triangulation of each of the tools with respect to the target tissue. This increase in distance can also provide a way of obtaining a larger field of view. The systems taught herein, for example, can (i) enable a working space to be dynamically configured around the target tissue in tortuous body lumens and orifices such as the gastrointestinal tract using controls from outside the body; (ii) provide a flexible, passageway for multiple surgical tools and instruments, such as endoscope and graspers to be passed from outside the body towards the target tissues; (iii) organize and/or constrain tools in the working space; (iv) at least substantially immobilize and/or stabilize the target tissue and surrounding tissue for a treatment; and/or (v) enable control over the geometry position, and orientation of the instruments such as the grasper in the working space from outside the body. 
     In some embodiments disclosed herein, an articulating endoscope is inserted through a channel of the catheter; in other embodiments the system is backloaded over a flexible endoscope, such as a conventional colonoscope, then the endoscope is inserted to a position adjacent the target tissue and then the catheter is advanced over the flexible endoscope so the reshaping (retractor) system (cage) is next to the target tissue. 
     In some embodiments disclosed herein, the endoscopic working instruments (tools) for treating the target tissue are inserted directly through a respective lumen or channel of the multi-lumen catheter. In these embodiments where the instruments (tools) are inserted directly into the lumen of channel of the catheter, the working instruments can have a curve at a distal end which automatically assumes the curved position when exposed from the catheter so it can curve toward the target tissue, or alternatively, the working instruments can have a mechanism actively controlled by the user to articulate/angle the distal tip. In other embodiments, instead of the endoscopic working instruments (tools) being inserted directly into the channel or lumen of the catheter, a flexible tube is inserted through the lumen or channel of the catheter and acts as a guide for the instrument. That is, the flexible tube is first inserted into the lumen or channel of the catheter and then the endoscopic instrument is inserted through the respective flexible tube. The flexible tube can have a curve at a distal end which automatically assumes the curved position when exposed from the catheter so it can curve toward the target tissue, or alternatively, the flexible tube can have a mechanism actively controlled by the user to articulate/angle the distal tip. In these embodiments utilizing the flexible tubes, the curving and maneuverability of the flexible tubes controls the positioning and orientation of the endoscopic instruments, and therefore the endoscopic instruments need not be provided with a pre-curved tip or articulating mechanisms. 
     In preferred embodiments, the systems disclosed herein include a retractor which creates an asymmetric working space within the body lumen. More particularly, when working in a confined body lumen, such as the colon, expansion of the lumen is limited because it is undesirable to over-expand which could stretch the lumen beyond its ability to return to its normal state or more dangerously could rupture the lumen. The asymmetric working spaces disclosed herein are designed to reconfigure or reshape the body lumen-transform the cylindrical space within the body lumen to a non-cylindrical asymmetrical space (i.e., changing the geometry) to shift the space around the target tissue to create more working space around the target tissue to provide both visual and mechanical improvements. Stated another way, in a cylindrical working space, there is a lot of area of unused space while in the reshaping of the embodiments disclosed herein the space is moved or shifted to reduce the unused space and create a larger area for tissue access and treatment. 
     The terms “treat,” “treatment”, and “treating” used herein include, for example, the therapeutic and/or prophylactic uses in the prevention of a disease or disorder, inhibition of a disease or disorder, and/or amelioration of symptoms of disease or disorder. The term “subject” and “patient” can be used interchangeably and refer to an animal such as a mammal including, but not limited to, non-primates such as, for example, a cow, pig, horse, cat, dog, rat, and mouse; and, primates such as, for example, a monkey or a human. 
     In some embodiments, the systems taught herein can include dynamically reconfigurable, asymmetric retractor structures on the distal end of a flexible and torque-able multi-channel shaft having a handle that allows for control over both the stiffness and geometry of the working space formed by the expansion of the retractor. In some embodiments, the retractor can include a stabilizer subsystem having 2-8, 3-5, 4-6, or any range therein, flexible retractor elements. In some embodiments, the retractor elements can be aligned at least substantially parallel to each other when fully collapsed for positioning in the patient. In some embodiments, the retractor elements are aligned on planes that are within about 5-30 degrees, about 10-25 degrees, about 15-20 degrees, about 15 degrees, or any range therein, of each other. In some embodiments, the retractor elements form a frame that has a length ranging from about 4-12 cm. 6-10 cm, 7-9 cm, 5-11 cm, or any range therein. In some embodiments, the frame is about 8 cm long. In some embodiments, the retractor elements form a frame that has a width ranging from about 1-5 cm. 2-4 cm, or any range therein. In some embodiments, the frame is about 3 cm wide. In some embodiments, the retractor elements form a frame that has a height ranging from about 1-5 cm. 2-4 cm, or any range therein. In some embodiments, the frame is about 3 cm high. One of skill will appreciate that there are a number of suitable materials that can be used to make the retractor elements for the purposes set-forth herein. In some embodiments, the retractor elements can be made from NITINOL. In some embodiments, the retractor element can comprise multifilament steel wires or polymer cords. The polymer materials can include polyetheretherketone (PEEK), nylon, polyester, polycarbonate, polyurethane, or polyethylene. The gauge of the retractor elements can vary, depending on material. In some embodiments, the retractor elements can comprise wires that range from about 0.020″-0.40″ in diameter. In some embodiments, the retractor elements are about 0.030″ in diameter. 
     The term “about” is used in the teachings herein to describe possible variations in amounts or ranges that can be used in embodiments. It can be used in embodiments, for example, to include the exact amount or range specified, as well as a variation of which that would not create a substantial difference in function. A difference in function can be insubstantial, for example, where it is less than 20% in some embodiments, less than 15% in other embodiments, less than 10% in yet other embodiments, or perhaps even less than 5% in yet other embodiments. One of skill will appreciate that the percentage difference in function required for to be substantial will depend on the function of the embodiment itself that is under comparison. 
     The methods, devices, and systems taught herein can be used for minimally-invasive procedures. A non-invasive procedure, in contrast, can be defined as a procedure that includes no violation of the skin or the mucosa, and no appreciable damage to any other tissues of the body. A minimally-invasive surgical operation, on the other hand, involves minimal access trauma and minimal collateral tissue damage during a surgical operation. The terms “minimal,” “minimize,” “minimizing,” “minimized,” “avoid,” “avoiding,” “avoided,” can be used interchangeably in some embodiments. Minimally-invasive surgery is desirable, for example, to reduce trauma to the patient, speed the healing process, reduce risk and, thus, reduce the length and expense of a hospital stay by minimizing or avoiding tissue damage, or risk of tissue damage. Tissue damage, or the risk thereof, can be minimized or avoided, for example, where a procedure is designed to minimize or avoid unnecessary tissue contact that may otherwise be associated with a procedure. The gentle procedures taught herein, for example, are directed to preserving tissue during a gastrointestinal surgery. 
     The systems taught herein can be dynamic in some embodiments, for example, such that the tissue retraction can include partial or complete expansion or collapse of a retractor to facilitate an increase or decrease in the distance between instruments and the target tissue, which is useful in reconfiguring the work space and aiding in axial movements of the tools. By increasing and releasing the tension, the amount of tissue to be placed in the working space can also be better-gauged during a procedure, for example, and tissue traction-contra-traction can be facilitated to help in creating a dissecting plane during a removal of tissue. One of skill will appreciate having the ability to dynamically reconfigure the working space and optimize traction-contratraction on the target tissue, as this can facilitate surgical manipulations. 
     The systems disclosed herein also enable triangulation to be achieved. Tissue triangulation, wherein the tissue is triangulated between two endoscopic instruments, enhances access and maneuverability. 
       FIG.  1    illustrates a system for operatively treating gastrointestinal disorders endoscopically in a stable, yet dynamic operative environment, and in a minimally-invasive manner, according to some embodiments. The system  100  can include a multi-lumen-catheter retractor system for ease of positioning in a subject, and such systems can be designed to provide a minimally invasive treatment of the subject. The system  100  can have a flexible outer tube  105  configured for guiding one or more channels  110  and an endoscope  115  within the system  100 . The flexible outer tube  105  can have a lumen (not shown), a proximal end (not shown), and a distal end  108  to house, for example, the channel(s) and the endoscope during use of the system  100 . The lumen can extend from the proximal to the distal end so the tool channels  110  can be manipulated at a proximal end by the user. The outer tube  105  can alternatively be a multi-luminal tube, so a separate lumen accommodates the endoscope and the individual tool channels, and during the use of the system  100 , the channel  110  can serve as a guide through which a tool  120 , 125  can be inserted and manipulated in a treatment of a target tissue  190  in the gastrointestinal tract  195  (or other areas) of the subject. The channel  110  can, for example, be in operable contact with an independently manipulable-and-articulable tool, the channel having an elevator component for moving a bendable section. Thus, the length of the channel in some embodiments is sufficient so it can extend out the proximal end of the outer tube  105  for manipulation by the user. The tool channels are bendable or articulable at a distal end so they angle away from the longitudinal axis and toward the target tissue  190 . Such bendability can be achieved by providing tool channels (guides)  110  of shape memory material with a shape memorized bent position as shown in  FIG.  1   . When contained within the lumen of the outer tube  105  for insertion, the tool channels  110  would have a substantially straightened position, and when advanced from the distal end of the outer tube  105 , would return to the bent position of  FIG.  1   . Other materials could also be utilized. In alternate embodiments, the tool channel  110  can have a mechanism such as an elevator component or a control wire attached to a distal end which can be pulled by the user or pulled by an actuator to move the tool channel to the bent position. These different ways to achieve bendability (articulation) of the tool channels can be used for the various embodiments of the systems described herein. 
     In some embodiments, the tool inserted through the tool channel can be any tool known to one of skill. For example, the tool  120 , 125  can include a grasper, a forceps, a snare, a scissor, a knife, a dissector, a clamp, an endoscopic stapler, a tissue loop, a clip applier, a suture-delivering instrument, or an energy-based tissue coagulator or cutter. The bendability of the channel  110  for moving a bendable section, often a distal end of the channel  110 , manipulates, i.e., bends, the tool  120 , 125  positioned therein. In some embodiments, at least one channel  110  and/or the endoscope  115  can have at least substantial freedom to move within the outer tube  105  during operation, or “float,” such that the system  100  can be considered to be a floating, multi-lumen-catheter retractor system. It should be appreciated that the terms “tool” and “instrument” can be used interchangeably in some embodiments taught herein. As can be appreciated, the tool  120 , 125  can be flexible, at least at a distal end such that when the tool channel  110  bends in a manner described above, it also bends the tool which is positioned therein. Alternatively, it is also contemplated that the tool  120 , 125  can be articulable or controllably bendable or composed of shape memory or other material so it bends without reliance on the bendability of the tool channels  110 . 
     Although two tool channels  110  are illustrated, it should also be appreciated that a system with more than two tool channels or with only one tool channel can also be utilized. Additionally, the endoscope can have a working channel for insertion of a working instrument such as a grasper or dissector. 
     It is also contemplated that the tools can be provided with bendability characteristics so that they can be inserted directly through the lumen of the outer tube  105  without the need for tool channels. In these embodiments, the tools themselves have the bendable or articulable feature so as not to rely on the tool channels for bending/angling toward the target tissue. 
     In some embodiments, the system can comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor  150 , as shown in  FIG.  1   , that expands to form a treatment space or working chamber  160  in the subject. The retractor  150  can be configured, for example, for the expansion to occur distal to the distal end  108  of the outer tube  105 . In some embodiments, the retractor can at least substantially render the target tissue  190  aperistaltic for the treatment. The retractor  150  can have a variety of configurations to serve, for example, as a scaffolding within the gastrointestinal tract  195 . For example, the retractor  150  can include retractor elements  151 , 152 , 153 , 154 , along with a proximal coupler  198  operably connected to the retractor elements  151 , 152 , 153 , 154 , whether at least substantially attached and/or at least slidably-engaged to the retractor elements  151 , 152 , 153 , 154 , and a distal nexus or hub (or coupler)  199  for a distal point of an operable connection with the retractor elements  151 , 152 , 153 , 154 . 
     In the embodiment of  FIG.  1   , retractor element  151  is a flexible element having a proximal portion  151   a  extending from the proximal coupler  198  at a first angle, a distal portion  151   b  extending from the distal hub or coupler  199  at a second angle preferably different from the first angle, and an engaging portion  151   c , which engages the tissue, extending between the proximal and distal portions  151   a ,  151   b . As shown, portion  151   a  extends at a greater angle to the longitudinal axis than distal portion  151   c  providing an asymmetric expansion of the retractor element itself. Thus, the length of the distal portion  151   b  exceeds the length of proximal portion  151   a . Retractor element  152  can be similarly configured and angled as retractor element  151 , or alternatively of a different configuration and angle. Retractor elements  151  and/or  152  can alternatively be configured so the proximal and distal portions are of the same length and angles. Note the retractor elements  151 ,  152  expand in a direction to one side of the longitudinal axis. This asymmetric expansion creates an asymmetric chamber described below. 
     The retractor  150  can be a reversibly-stabilized and reversibly-expandable retractor, the retractor  150  forming an asymmetrical treatment space  160  upon the expansion. And, the retractor  150  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  150 , the arrangement designed to facilitate ease of positioning of the system  100  in the subject and to reversibly stiffen for the expansion of the retractor  150 . The stabilization of the retractor  150  can, in some embodiments, include a stabilizer subsystem for stabilizing the retractor  150  as taught herein, the stabilizer having, for example, an at least substantially-rigid beam  175  to support the expanded retractor  150 . 
     Rigidifying the retractor systems as disclosed in the various embodiments herein, i.e., by utilizing a substantially rigid beam, advantageously stabilizes the retractor system, i.e., limits bending of the distal tip which could otherwise occur due to the opposing force of the tissue during expansion. Thus, the stabilizer carries the load and works to create a more stabilized chamber. In some embodiments, beam  175  can be substantially rectangular in cross-section, substantially circular in cross-section or of other cross-sectional shapes. It can be provided of a stiffer material than the retractor elements. In some embodiments, the beam can have a cross sectional dimension larger than a cross sectional dimension of the retractor element. As shown in  FIG.  1   , the beam  175  is at the base of the chamber formed by the retractor elements, with the retractor elements extending radially (laterally) away from the beam  175 . The beam  175  can be formed by the more rigid element exposed when the retractor elements are exposed from the outer tube for expansion, or alternatively, can be advanced independently from within the outer tube as in some of the embodiments described in more detail below. 
     In some embodiments, the outer tube can have any dimensions believed to be useful to one of skill for the purposes taught herein. For example, the outer tube can have an outer diameter ranging from about 3 mm to about 30 mm, about 5 mm to about 25 mm, about 7 mm to about 22 mm, from about 9 mm to about 20 mm, from about 11 mm to about 18 mm, from about 8 mm to about 15 mm, from about 10 mm to about 16 mm, or any range therein in increments of 1 mm. The length of the outer tube can range, for example, from about 30″ to about 72″, from about 31″ to about 36″, from about 28″ to about 80″, from about 32″ to about 40″, from about 34″ to about 38″, or any range therein in increments of 1″. 
     The outer tube can be manufactured from any materials know to be useful to one of skill for the purposes taught herein. For example, the outer tube can comprise a polymer, or perhaps a polymer having an embedded wire reinforcement. The wire reinforcement can be a mesh, a braid, a helical coil or any combination thereof. The wire reinforcement can include any material believed by one of skill to be useful for the purposes set-forth herein. For example, wire reinforcement can comprise a material having an elastic modulus that is about 1-3 orders of magnitude higher than the polymer tube. The wire material can comprise, for example, a stainless steel having a diameter ranging from about 0.003″ to about 0.017″, about 0.005″ to about 0.015″, about 0.010″ to about 0.012″, or any range therein in increments of about 0.001″. The tube hardness, or durometer, can be any of that which one of skill will find useful for the purposes set forth herein. For example, the hardness can range, for example, from about 50 Shore A to about 60 Shore A, about 40 Shore A to about 80 Shore A, about 45 Shore A to about 70 Shore A, or any range therein in increments of 1 Shore A. One of skill will appreciate that the outer tube should be flexible, elastically bendable, but sufficiently stiff torsionally to transmit torque from the handle or proximal end of the system to the retractor or distal end of the system. 
     The outer tube can be connected to at a distal end to a ring, referred to herein as the proximal coupler in some embodiments, which can have portals formed therein for retractor elements to slide through, as well as a desired orientation and positioning of the channels for the endoscope and at least one tool, such that the retractor elements, endoscope, and at least one tool are organized relative to each other in a predetermined manner to achieve a particular function, such as an increase in working space, a better view of a plane of dissection, or any other procedural variable deemed of interest to one of skill. For example, in the embodiment shown in  FIG.  1   , the portals for the retractor elements are spaced radially outwardly from the portals for the endoscope and the tool channels. 
     In some embodiments, the retractor structures taught herein for substantially immobilizing the lesion to the extent desired for the treatment. For example, the current use of loops and a piece-meal removal of flat or wide-based polyps, such as those having a base of about 1 cm or wider, may not provide clear surgical margins, whereas the systems taught herein can, in some embodiments, immobilize or affix the entire circumference of the bowel wall around the treatment area and facilitate the production of clear surgical margins. One of skill will appreciate having a working space that can be provided by the systems taught herein, the working space being (i) at least substantially non-collapsible, (ii) at least substantially aperistaltic; and, (iii) at least substantially affixed at a particular point in the abdominal cavity in relation to any fixed body point, like a hip, for example. This is a significant improvement over existing systems, as existing systems have not addressed many existing problems including, for example, bowel collapse that can result from an air leak from the working space; peristalsis that is normal, even in a sedated patient; and, additional undesired bowel movements caused by the patient&#39;s breathing, movement of the scope or other instrument manipulation, or perhaps even by a surrounding peristalsis causing movement at a treatment area. Such problems are addressed by systems taught herein. As such, systems taught herein can offer a rigid, stable structure having at least substantial resistance to a variety of moving forces in the abdomen that are typically present during a gastrointestinal endoscopic procedure. One of skill will appreciate decreasing the effects of these moving forces on the working space to help reduce otherwise inherent technical complexities, limited efficacies, and decreased safety during endoscopic procedures. 
     In addition to creating the working space with the above advantages, the working space is formed to create a sufficient working distance for the tools for treatment, e.g., polyp dissection, to enhance maneuvering and manipulating the individual tools, enabling tissue triangulation. Working space distance is also advantageously formed to enhance visibility of the target tissue. 
     In some embodiments, the systems taught herein can be slidably positioned over an endoscope during use. In these embodiments, the endoscope would first be inserted to a position adjacent the target tissue and then the multi-lumen tube or catheter advanced over the endoscope, with the endoscope sliding over the endoscope receiving lumen (channel) of the outer tube or catheter. In fact, it should be appreciated that there are a variety of methods of using systems taught herein that are already used by one of skill in current state-of-the-art procedures. For example, the method can include inserting the multi-luminal tube into an overtube, cover, or sheath. And, in some embodiments, the endoscope can be a colonoscope. In many embodiments, regardless of the method of use, the retractor structures can mechanically retract one side of the colonic wall in an asymmetric manner to increase the distance between the target lesion and the opposite wall, as well as between the lesion and the instruments in their most retracted, but visualized, position to increase the effective work space. 
     In some embodiments, the systems can include a multi-lumen catheter having at least 2 working channels for manipulating tools and an endoscope, each of the two working channels having 6 degrees of freedom that are independent from each other and the endoscope. The ability to independently manipulate the endoscope and tools allows, for example, one instrument to retract the tissue or lesion away or substantially perpendicular to another instrument, for example, the dissecting instrument, while independently optimizing the endoscope&#39;s position and, hence, the view of the treatment area. This would facilitate the removal of tissue with clear margins. The channels can manipulate the tools with several degrees of freedom, 6 degrees of freedom in some embodiments, providing a greatly enhanced maneuverability in the working area when compared to current state-of-the-art systems. In some embodiments, the at least one independently manipulable-and-articulable tool can be independently rotatable to an angle of up to about 360 degrees, about 315 degrees, about 270, about 225 degrees, about 180 degrees, about 135 degrees, or about 90 degrees in the working area. In addition the tools can be independently bendable to an angle of up to about 180 degrees, about 135 degrees, about 90 degrees, or about 45 degrees in at least one direction in the working area. 
     The systems taught herein can provide for organizing the orientation of the floating channels, in order to further facilitate improving the flexibility of the system. In some embodiments, for example, the proximal coupler, the ring that can be attached to the distal end of the outer tube, can be used to organize the tools and endoscope in a particular arrangement to facilitate a particular positioning of the tools as they emerge from the shaft into the working space created by the retractor. In some embodiments, the tool channels can be placed further than the endoscope from the retractor elements that expand the most. Likewise, the proximal end of the outer tube can also have respective openings for each of the channels, and these openings can be, for example, a part of a handle coupler, or the handle itself, operably connecting one or more of the channels to the outer tube. The operable connection between the outer tube and channels can provide for controlling the endoscope and tools, for example, from outside the patient. The rings can be made of any material believed by one of skill to be suitable for the purposes discussed herein. For example, the rings can be made of stainless steel, or perhaps a plastic such as polycarbonate or acrylonitrile butadiene styrene (ABS). 
     It should be appreciated that, in some embodiments, the systems taught herein can include any combination of components, the selected combination of which is designed to be operable with components that are obtained separate from the system. For example, the system can include an outer tube and a retractor component, the outer tube being operable with at least one channel obtained separately and an endoscope obtained separately. Likewise, the system can include an outer tube, a retractor, and an endo scope, and the channels are obtained separately; or an outer tube, a retractor, and a channel, the endoscope obtained separately. Moreover, the system can include an outer tube, a retractor, an endoscope, and at least one channel; or, a handle, an outer tube, a retractor, an endoscope, at least one channel, and at least one tool. 
     The terms “substantial,” and “substantially” can be used, for example, to refer to a relative measure for a parameter. It can be used in some embodiments, for example, to refer to a degree of change or function that relates to an amount, a performance, or some other characteristic. The following are for purposes of example in describing general embodiments: As described, the systems can be considered to be floating systems, can have a floating channel, a floating endoscope, multiple floating channels, or a combination thereof, in some embodiments. For example, the phrase, “an at least substantially floating arrangement within the system”, can refer to an arrangement, for example a channel or endoscope arrangement, that can have some attachment that restricts movement in at least one direction, a minimal attachment to minimize such restriction of movement, or perhaps no attachment at all, to another system component. For example, a channel or endoscope can be arranged to be at least substantially floating in the outer tube relative to a second such system that does not use a floating-type arrangement to increase flexibility, or inherently achieve an increase in flexibility, of the second such system. As such, in many embodiments, the endoscope and/or channel can have a substantial portion of its arrangement unattached within the system, allowing the substantial portion to “float” or move substantially freely within the outer tube. The “substantial portion” can be, for example, a percentage of the arrangement that must remain unattached within the system to provide a performance characteristic, such as an increased flexibility of the system when compared to the second such system that does not use a floating-type arrangement to increase flexibility, or inherently achieve an increase in flexibility, of the second such system. 
     The phrase, “at least substantially render the target tissue aperistaltic for the treatment”, for example, can refer to the target tissue having some minimal peristalsis, or perhaps no peristalsis, under the conditions of normal use to provide a performance characteristic, such as controlling movement of the target tissue to facilitate treatment. The phrase, “at least substantially attached”, for example, “at least substantially attached to the lumen of the outer tube”, for example, can refer to a component having a fixed attachment or moveable attachment. In some embodiments, the attachment can be between the component and the lumen, such that there is a loss of at least one degree of freedom of movement of the component. For example, the component can slide and/or rotate in relation to the lumen of the outer tube, as long as the sliding and/or rotating occur in relation to a particular fixed point on the lumen. Likewise, “at least substantially attached” can, of course, mean “fixed”, “reversibly fixed,” or the like, in some embodiments. Likewise, “at least slidably-attached” can refer to an attachment between components that allows for at least sliding motion between components such as, for example, a sliding motion between a port and a tube. In some embodiments, an endoscope can be at least slidably-attached, for example, where the scope is allowed to slide in the direction of the scope&#39;s central axis in and out of a port, such that the distance that the scope extends beyond the port is adjustable. And, in some embodiments, a component can be “at least slidably-attached” where it can slide as well as move in other directions. For example, the port can be substantially larger than the scope, in some embodiments, such that the scope can slide axially, as well as move side-to-side, align its central axis parallel to the central axis of the outer tube, or perhaps, misalign its central axis to not be parallel to the central axis of the outer tube. 
     The phrase, “at least substantially increases the flexibility” can refer to an orientation of components that enhances the flexibility of a system when compared to another orientation and design of the components. For example the phrase “at least substantially increases the flexibility of the system over a second such system” can refer to a comparison of flexibility of the claimed system over the second system not having the floating arrangement under the conditions of normal use, such that the flexibility of the system has increased to a minimal amount that improves the ease of positioning the system in the subject for the treatment of the target tissue. 
     The phrase, “at least substantially rigid component,” can refer to a component that is rigid, or sufficiently rigid, such that the desired function is obtained, under the forces that are created with normal use. For example, a desired function may be to prevent or inhibit the occurrence of a bending moment of the rigid component at one or more points along the length of a retractor upon expansion of the retractor in the subject. In some embodiments, the systems taught herein can have a retractor with four retractor elements, at least two of which are expandable in the subject to create a working space for a treatment. In this example, the expansion of the at least two retractor elements toward the target tissue to create the working space requires a force sufficient to retract the tissue and, creates an opposing force in the opposite direction that can create the bending moment in the rigid component. One of skill should appreciate that such a bending moment can be problematic, for example, where it contributes to an instability that affects the user&#39;s control over the position of the retractor during a treatment of the target tissue. In such embodiments, a component that prevents or inhibits the bending moment can be “at least substantially rigid,” for example, where the user retains a desired level of control, or at least sufficient control, over the position of the retractor during the retraction of the target tissue. In some embodiments, a component that prevents or inhibits a bending moment, whether in or out of the subject, can be at least substantially rigid where the bending of the component due to the expansion of the retractor creates a deflection that ranges from 0.0 to about 5 degrees, about 1.0 degree to about 10 degrees, about 2.0 degrees to about 12 degrees, about 3.0 degree to about 10 degrees, about 1.0 degree to about 15 degrees, about 1.0 degree to about 9.0 degrees, about 1.0 degree to about 8.0 degrees, about 1.0 degree to about 7.0 degrees, about 1.0 degree to about 6.0 degrees, about 1.0 degree to about 5.0 degrees, about 1.0 degree to about 4.0 degrees, or any range therein in increments of about 0.1 degree. In some embodiments, the deflection of the rigid component cannot exceed about 1.0 degree, about 2.0 degrees, about 3.0 degrees, about 4.0 degrees, about 5.0 degrees, about 6.0 degrees, about 7.0 degrees, about 8.0 degrees, about 9.0 degrees, about 10.0 degrees, or any 0.1 degree increment therein. The bending can be measured, for example, as a point of deflection from the original position of the rigid component&#39;s axis from force created on the rigid component through the expansion. 
     The terms “substantial” or “substantially” can be used interchangeably in some embodiments, and can be described using any relative measures acceptable by one of skill. For example, relative percentages can be used to indicate a substantial amount, substantial change, substantial difference, substantial function, or the like. In some embodiments, the percentage can be greater than 10%, greater than 20%, greater than 30%, greater than 40%, or greater than 50%. In some embodiments, the percentage can be greater than 60%, greater than 70%, or greater than 80%. And, in some embodiments, the percentage can be greater than 90%, greater than 95%, or in some embodiments, even greater than 99%. For example, a substantial [amount]” or a “substantial [change]”, can include any amount or change relative to a reference parameter. The amount or change, for example, can include an increase or decrease relative to the reference parameter, can be compared to a reference point for the parameter. The deviation from the reference point can be, for example, in an amount of at least 1%, at least 2%, at least 3%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, or any 1% increment therein. Also, for example, a “substantial [function]” or “substantially [functioning]” limitation can serve as a comparison to a reference function parameter, to indicate a deviation that will still provide the intended function. Reference functions can include, for example, floating, aperistalsis, attaching, flexing, rigidity, a position or positioning relative to another object, and the like. The deviation from the reference point can be, for example, in an amount of less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, less than 25%, less than 30%, less than 35%, less than 40%, less than 45%, or any 0.1% increment therein. For example, a component can have an acceptable, substantial [function] when it deviates from the reference by less than the acceptable deviation. 
     As such, the system can include a floating, multi-lumen-catheter retractor system for ease of positioning in a subject, and such systems can be designed to provide a minimally invasive treatment of the subject. In some embodiments, the systems comprise a highly flexible outer tube configured for guiding a floating channel and/or a floating endoscope in an at least substantially floating arrangement within the system. This flexible outer tube can have a lumen, a proximal end, and a distal end. And, during a use of the system, the floating channel can serve as a guide through which a tool is manipulated in a treatment of a target tissue in a subject. In some embodiments, the tool can include a grasper, a forceps, a scissor, a knife, a dissector, an endoscopic stapler, a tissue loop, a clip applier, a suture-delivering instrument, or an energy-based tissue coagulator or cutter. And, in some embodiments, the floating channel can have an elevator component for moving a bendable section to manipulate the tool. In some embodiments, at least one channel and/or the endoscope can have at least substantial freedom to move within the outer tube during operation, or “float,” such that the system can be considered to be a floating, multi-lumen-catheter retractor system as taught herein. 
     Likewise, the system can also comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor (working space expanding system) that expands to form a treatment space in the subject. The retractor can be configured, for example, for the expansion to occur distal to the distal end of the outer tube and at least substantially render the target tissue aperistaltic for the treatment; wherein, during a use of the system in a subject, the floating channel can be at least substantially attached to the lumen of the outer tube at a first proximal location and a first distal location, and be at least substantially floating in the lumen of the outer tube between the first proximal location and the first distal location. Likewise, during the use of the system, the floating endoscope can be at least slidably-attached to the lumen of the outer tube at a second proximal location and a second distal location, and be at least substantially floating in the lumen of the outer tube between the second proximal location and second distal location. And, during the use of the system, the at least substantially floating arrangement can at least substantially increase the flexibility of the system over a second such system, the second such system having a lumen for a tool and an endoscope affixed to the lumen throughout the length of the outer tube between the proximal end and the distal end of the outer tube. The increased flexibility of the at least substantially floating arrangement can facilitate an ease of positioning the system in the subject for the treatment of the target tissue. Moreover, the retractor can be a reversibly-stabilized and reversibly-expandable retractor, the retractor forming an asymmetrical treatment space upon the expansion. And, the retractor can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor, the flexible arrangement designed to facilitate the ease of positioning of the system in the subject and to reversibly stiffen for the expansion of the retractor. 
       FIGS.  2 A and  2 B  illustrate how a system as taught herein can be positioned for treating a lesion in the ascending colon, according to some embodiments. It should be appreciated that any series of steps and methods known to one of skill to be useful in the positioning  200  can be used with systems taught herein.  FIG.  2 A  illustrates how an endoscope  215  can be used to locate the lesion, a target tissue  290  in a portion of the ascending colon  295 .  FIG.  2 B  illustrates how the multi-lumen-catheter retractor system  201  can be guided to the target tissue  290  using the endoscope  215  as a guide for the positioning  200  of the system in the treatment of the target tissue  290 . As can be appreciated, the multi-lumen catheter is advanced over the endoscope  215  as shown in  FIG.  2 B . 
       FIGS.  3 A- 3 L  illustrate how a system as taught herein can be used in removing a lesion in a colon, according to some embodiments. As noted above, the system can also be used in other areas of the patient&#39;s body and to treat other target tissue. The description herein regarding removal of a polyp from the wall of the colon is shown and described by way of example as the system (as well as the other systems disclosed herein) can be used for other surgical applications and in other body spaces. The system can be positioned as in  FIGS.  2 A and  2 B  in the treatment  300  of a gastrointestinal lesion  390 , and a multidirectional and multi-angular approach to the lesion can be used. As in  FIGS.  2 A and  2 B , for example, the approach can include identifying a lesion in a gastrointestinal lumen of a subject using an endoscope  315 ; and, forming a substantially rigid and stable endoluminal working area for treating a target tissue, the gastrointestinal lesion  390 . In  FIG.  3 A , the system is positioned at the lesion  390 , and in  FIG.  3 B , the expandable retractor  350  is exposed for subsequent expansion to create an asymmetrical working space  360  ( FIG.  3 C ). In  FIG.  3 A , a sheath or cover  355  is positioned over the retractor elements to facilitate insertion, with the distal end of the sheath  355  abutting the distal coupler  399  or alternatively overlying the distal coupler. After insertion to the target site, the sheath (or outer tube)  355  is removed to expose the retractor elements for subsequent expansion as shown in  FIG.  3 B . It should also be appreciated that, alternatively, the retractor elements can be biased to an expanded position and retained in a collapsed delivery position by the sheath  355 . In such embodiments, removal of the sheath  355  to expose the retractor elements would enable the retractor elements to automatically expand to their expanded position of  FIG.  3 C . 
       FIGS.  3 C and  3 D  illustrate the creation of the working space  360  within the body lumen, and manipulation of the endoscope  315  and tools  320 , 325 . After positioning the retractor  350  in proximity to the lesion  390 , the retractor  350  is expanded to form the asymmetrical working space  360  for the treating of the lesion  390 . The retractor  350  in some embodiments can be expanded by moving distal coupler  399  and proximal coupler  398  relative to one another, wherein as the distance between the couplers  399 ,  398 , shortens, the retractor elements are forced more laterally with respect to the longitudinal axis of the outer tube (catheter)  305 . In alternate embodiments, the retractor elements can be operably connected to an actuator such that the actuator is moved to bow the retractor elements such as in the embodiment of  FIG.  11    discussed in detail below. In still other alternative embodiments, the retractor elements can be composed of a shape memory or other material such that when exposed from the outer tube or sheath, they automatically return to their expanded configuration, e.g., their shape memorized expanded configuration. When such shape memorized retractor elements are utilized, once exposed they would automatically move from the position of  FIG.  3 B  to the position of  FIG.  3 C . 
     The system can have any configuration taught herein, such as (i) at least one independently manipulable-and-articulable scope  315  to be used in viewing the lesion  390 , (ii) at least one tool channel  310  for at least one independently manipulable-and-articulable tool  320 , 325  to be used in the treating of the lesion  390 , and (iii) the retractor  350 , which can be an asymmetrically expandable structure. In some embodiments, the retractor  350  can be expanded asymmetrically toward the lesion  390 , the expanding including a portion of the retractor  350  pushing on tissue surrounding the lesion  390  to increase the working area (space) within the body space (lumen) by providing an asymmetrical working area and thus facilitate an entry of the lesion  390  into the working area  360  for the treating. The retractor  350  can be located distal to the distal end of the outer tube  305  and the asymmetrical working area  360  can be substantially rigid and stable relative to the independently manipulable-and-articulable scope  315  and the at least one tool  320 , 325  to facilitate treating the lesion  390 . The treating of the lesion  390  can include, for example, (i) viewing the lesion  390  with the articulating scope  315  and (ii) using the at least one tool  320 , 325  in the treatment of the lesion  390  with a multidirectional and multi-angular approach to the lesion  390  in the asymmetrical working area  360 . 
     In the embodiment of  FIGS.  3 A- 3 J , four retractor elements are provided. Two retractor elements  353 ,  354  are at the base of the retractor system and can have an outwardly bowed or arcuate shape, or alternatively, a substantially straight shape, or have accurate and substantially straight portions. Two retractor elements  351 ,  352  expand more radially outwardly to apply a force against the wall of the colon on which the lesion is found. These retractor elements are described in more detail below. 
     In some embodiments, the independently manipulable-and-articulable scope  315  and the at least one tool  320 , 325  can be independently movable axially in the working area  360 , independently rotatable in the working area  360 , and independently bendable in at least one direction in the working area  360 . Accordingly, in some embodiments, the portion of the retractor  350  pushing on the tissue surrounding the lesion  390 , e.g. retractor elements  351 ,  352 , can be expanded further from the central axis  307  of the distal end of the outer tube  305  than other portions of the retractor to provide an even larger working area  360  for the treating of the lesion  390  when compared to a second such structure that merely expands symmetrically around the central axis  307  of the distal end of the outer tube  305 . This is due to the fact that it is desirable to create the largest working distance from the instrument tips to the target tissue, achieved by changing the configuration, i.e., reshaping, of the colon in the target area, but without overstretching, damaging or rupturing the colon. 
     Note that after the retractor system is expanded as shown in  FIG.  3 C , the endoscope  315  can be articulated in the working space  360  toward the target lesion  390  to improve visibility. 
       FIG.  3 E  illustrates a multidirectional and multi-angular approach to the lesion  390 , showing the step of positioning the work area  360 , endoscope  315 , and tools  320 , 325  in relation to the lesion  390 . After the retractor  350  is expanded as shown in  FIG.  3 C , the user of the system can view and approach the lesion  390  with the tools  320 , 325  from nearly any desired angle within the working space  360 . The tool channels  310  are advanced through the respective lumens in the multi-lumen catheter or tube and the endoscopic tools or instruments are inserted through the tool channels  310 , with the distal ends of the tools extending distally of the tool channel  310  as shown in  FIG.  3 D . The advantages of the tool channels are described below in more detail in conjunction with the embodiment of  FIG.  11   , and such advantages are applicable to this and other embodiments utilizing the tool channels. As noted above, it is also contemplated that in alternative embodiments, the endoscopic tools can be inserted directly into the lumens of the catheter or tube, without the use of tool channels, provided they have the bending/articulating characteristics described above which enable their manipulation without the use of bendable/articulatable tool channels. 
       FIG.  3 F  illustrates the versatility of the system, showing the step of removing the lesion  390  using tool  320  to excise the lesion  390  from an independently chosen first angle, while tool  325  can be used to grasp the lesion  390  from an independently chosen second angle and endoscope  315  can be used to view the lesion  390  from an independently chosen third angle. As shown, the different angling of the tools  320   325  advantageously achieve tissue triangulation to facilitate access, maneuverability and removal of the lesion. After the excision of the lesion  390  from the gastrointestinal tract  395  by the dissection tool  320 , a tissue defect  397  remains. Note the dissection tool  320  can in some embodiments be in the form of an electrosurgical instrument, although other dissecting/excising tools can also be utilized.  FIG.  3 G  illustrates the step of releasing the excised lesion  390  into the retractor assembly in preparation for completion of the procedure.  FIGS.  3 H and  3 I  illustrate the step of closing the tissue defect  397 , showing that tool  320  for excision of the lesion  390  has been replaced by tool  322  for closure of the lesion. The lesion can be closed by various methods such as mechanical (e.g., clips staples or structures), glue, electrosurgical energy, etc.  FIGS.  3 J and  3 K  illustrate the steps of capturing the lesion  390  for removal using tool  323  and collapsing the retractor  350  to capture and contain the lesion  390  within the collapsed retractor elements  351 ,  352 ,  353 ,  354  in preparation for removal of the system from the subject, including the use of an optional retractor cover  355  or other sheath or sleeve which can be slid over the catheter to further encapsulate the lesion retained within the collapsed retractor elements.  FIG.  3 L  is a view of the closed tissue defect following completion of the treatment. 
     In some embodiments, as shown for example in  FIGS.  3 B- 3 J , the system can comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor  350  that expands to form a treatment space  360  in the subject. The retractor  350  can be configured, for example, for the expansion to occur distal to the distal end  308  of the outer tube (catheter)  305 . In some embodiments, the retractor can at least substantially render the target tissue  390  aperistaltic for the treatment. The retractor  350  can have a variety of configurations to serve, for example, as a scaffolding within the gastrointestinal tract  395 . For example, the retractor  350  can include retractor elements  351 , 352 , 353 , 354 , along with a proximal coupler or hub  398  operably connected to the retractor elements  351 , 352 , 353 , 354 , whether at least substantially attached and/or at least slidably-engaged to the retractor elements  351 , 352 , 353 , 354 , and a distal nexus or coupler  399  for a distal point of an operable connection with the retractor elements  351 , 352 , 353 , 354 . The distal nexus or hub  399  is shown in the shape of a ring, although it can be virtually any shape desirable to one of skill, such as a cone, hemisphere, sphere, and the like, and it may or may not include a port for passage of the endoscope beyond the distal end of the system. As noted above, in some embodiments, the proximal coupler  398  can be moved toward the distal coupler  399 , the distal coupler moved toward the proximal coupler  398 , or both couplers moved toward each other to reduce their distance to force the retractor elements radially outwardly. The extent of outward expansion of the retractor elements can be controlled by controlling the distance between the proximal and distal couplers  398 ,  399 , The retractor can be repeatedly moved between expanded and retracted positions as desired by adjusting the distance between the coupler  398 ,  399 . Such controlled expansion of the retractor elements can also be achieved by operatively coupling the proximal end of the retractor elements to an actuator as in the embodiment of  FIG.  11   . Alternatively, as noted above, the retractor elements can be composed of a material, e.g., shape memory material, to automatically expand when exposed from a catheter or sheath. 
     In the expanded position of the retractor elements as shown, retractor element  351  is a flexible element having a proximal portion  351   a  extending from the proximal coupler  398  at a first angle, a distal portion  351   b  extending from the distal hub or coupler  399  preferably at a second angle different from the first angle, and an engaging portion  351   c , which engages the tissue, extending between the proximal and distal portions  351   a ,  351   b . As shown, portion  351   a  extends at a greater angle to the longitudinal axis than distal portion  351   b  providing an asymmetric expansion of the retractor element itself. Thus, the length of the distal portion  351   b  exceeds the length of portion  351   a . Retractor element  352  can be similarly configured and angled as retractor element  351 , or alternatively of a different configuration and angle. Retractor elements  351  and/or  352  can alternatively be configured so the proximal and distal portions are of the same length and angles. Note the retractor elements  351 ,  352  expand in a direction to one side of the longitudinal axis. This asymmetric expansion creates an asymmetric chamber (working space). Retractor elements  351 ,  352  can extend in an arcuate or bowed manner or substantially straight manner as mentioned above. In some embodiments, the retractor elements  351 ,  352  only expand in one direction with respect to the longitudinal axis of the catheter so they remain above (as viewed in the orientation of  FIG.  3 D ) a longitudinal plane containing the longitudinal axis. In some embodiments, only elements  351 ,  352  expand while elements  353 ,  354 , which form the base of the retractor (cage) remain in substantially the same position in the insertion (collapsed) and expanded position of the retractor. Note as with the retractor elements of  FIG.  1   , the elements  351 ,  352 ,  353 ,  354  can be covered with a plastic or other material to create a covered chamber as in the embodiment of  FIG.  10 A  described below. 
     The retractor  350  can be a reversibly-stabilized and reversibly-expandable retractor, the retractor  350  forming an asymmetrical treatment space  360  upon the expansion. And, the retractor  350  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  350 , the arrangement designed to facilitate ease of positioning of the system  300  in the subject and to reversibly stiffen for the expansion of the retractor  350 . The stabilization of the retractor  350  can, in some embodiments, include a stabilizer subsystem as taught herein, the stabilizer having, for example, an at least substantially-rigid beam  375  to support the expanded retractor  350 . The substantially rigid beam  375  can be substantially rectangular in cross-section, substantially circular in cross-section or of other cross-sectional shapes. It can be provided of the same or of a stiffer material than the retractor elements. It helps to create a more stabilized chamber as described herein. As shown, the beam  375  is at the base of the chamber formed by the retractor elements, with the retractor elements extending radially (laterally) away from the beam  375 . The beam  375  can be formed by the more rigid element exposed when the retractor elements are exposed from the outer tube for expansion, or alternatively, can be advanced independently from the outer tube or formed by advancement of a rigidifying structure as in some of the embodiments described in more detail below. 
       FIGS.  4 A- 4 E  illustrate details of an alternate system as taught herein, in side, axial, and oblique views of expanded and collapsed configurations, and including a stabilizer subsystem, according to some embodiments. The figures illustrate an example of a multi-lumen catheter system which is similar to the system of  FIGS.  3 A- 3 K  in that it has a reversibly-stabilized and reversibly-expandable retractor for a minimally invasive treatment of a subject.  FIGS.  4 A- 4 C  illustrate side and axial views that show that the system  400  can comprise a flexible outer tube (or catheter)  405  for guiding a tool channel (not shown) and an endoscope (not shown) within the system  400  in the same manner as system  300 . The flexible outer tube  405  has a lumen, a proximal end (not shown), and a distal end  408 . The one or more tool channels (not shown) serves as a guide through which an endoscopic tool (not shown) can be manipulated in a treatment of a target tissue in a subject in the same manner as tool channels  310  of  FIG.  3 G  manipulate tools  320 ,  325 . In some embodiments, the retractor  450  can be a reversibly-stabilized and reversibly-expandable retractor  450  forming a treatment space upon expansion and configured for the expansion to occur distal to the distal end  408  of the outer tube  405 . The retractor  450  can be designed to reversibly-stiffen an otherwise flexible arrangement of the retractor  450 , the flexible arrangement designed to facilitate the positioning of the system in the subject and to reversibly-stiffen for the expansion of the retractor  450 . In these embodiments, the reversibly-stiffened arrangement of the retractor  450  can form an at least substantially-rigid beam  475  from an otherwise flexible beam  470  as a structural support for the expansion of the retractor  450 . In some embodiments, the stabilizer subsystem can include the flexible beam  470 , which may comprise a flexible tube, and a way for creating the at least substantially-rigid beam  475 . This, as taught herein, can include all embodiments taught herein, including the mechanisms for slidably-engaging an at least substantially-rigid rod or beam, for example, within the flexible rod or beam  470  prior to expanding the retractor. In some embodiments, the terms “rod” and “beam” can be used interchangeably and, in some embodiments, the terms “beam” and “tube” can be used interchangeably. The beam  475  can be configured and function in the same manner as described above for beam  375 , including the alternatives described herein. 
     In some embodiments, the flexible beams taught herein in each of the embodiments disclosed can comprise a polymer, such as polyimide, polyether block amides (PEBAX), nylon, polyethylene, polyurethane, polyvinylchloride (PVC), PEEK, or polytetrafluoroethylene (TEFLON). One of skill will appreciate that the flexible beams can be reinforced tubes made from components and designs known to the art. The flexible beam can be, for example, a flexible tube that is reinforced with metal wires, braids, or coils that include, for example, a metal such as a stainless steel or NITINOL. In some embodiments, the flexible tube can be kink resistant and transmit torque. And, in some embodiments, the flexible tube can comprise a combination of both flexible sections and rigid sections. In these embodiments, a flexible section can lie between rigid sections, for example. Such flexible tubes can include composites of overlapping tubes joined using any method known to one of skill, including bonding using epoxy or cyanoacrylates, in some embodiments. 
     In some embodiments, any of the systems taught herein can include a bridge member to add stability to the retractor. For example, the retractor system  450  can include a bridge member  444  configured to maintain a desired orientation of the retractor elements  451 , 452 , 453 , 454  during the expansion, the bridge member  444  operably stabilizing at least two  451 , 452  of the four retractor elements  451 , 452 , 453 , 454 . That is, in the embodiment of  FIG.  4 A , the bridge member  444  is attached to the two retractor elements  451 ,  452  which are configured to expand laterally outwardly to expand or reconfigure the tissue wall. The bridge member  444  creates a transverse structure for the elements  451 , 452 , limiting side-to side movement. As shown, bridge member  444  can also include a second bridge section  444   a  connected to bridge  444  and to retractor elements  452  and  453  thereby connecting all four retractor elements  451 ,  452 ,  453 ,  454 . The upper surface (as viewed in the orientation of  FIG.  4 B ) can be arcuate as shown. The bridge member  444  can be a separate component or alternately integrally formed with one both of the retractor elements  451 ,  452 . The bridge member can be composed of a material similar to the elements  451 ,  452  or can be composed of a different material. 
     Additional bridge members can be provided on the retractor elements  451 ,  452  to increase stability. Note that one or more bridge members can be used with the other retractor embodiments disclosed herein. Note that the bridge member  444  can, in some embodiments, in the collapsed position, angle radially outwardly from the longitudinal axis such as in  FIGS.  4 B and  4 D , but change to angle more radially inwardly in the expanded position of  FIGS.  4 C and  4 E . 
     Additionally, an additional bridge member (or multiple bridge members) can extend between the two lower (as viewed in the orientation of  FIG.  4 C ) retractor elements  453 ,  454  independent of bridge member  444 . These elements  453 ,  454  can help open up the lower section of the retractor system, and the bridge member(s), whether independent or connected to bridge  444 , can help to stabilize these elements, e.g., limit side to side movement. Such bridge members on the lower retractor elements can be used with the other retractor embodiments disclosed herein. 
     In some embodiments, each of the systems taught herein can have an outer tube that is wire-reinforced, such as mesh, braided, or the like, to provide kink resistance and torqueability to the system, as well as to further facilitate a positioning of the system in the subject. 
       FIGS.  4 D and  4 E  illustrate oblique views of the system  400  in collapsed and expanded configurations. The multi-lumen concept is presented with clarity in these figures, showing multiple lumens  406   a ,  406   b ,  406   c  in the catheter  405  in system  400 . Lumen  406   a  can contain an endoscope (not shown) such as endoscope  315  described above, lumen  406   b  can contain a first working channel  410   b  for a first endoscopic tool (not shown), and lumen  406   c  can contain a second working channel  410   c  for a second endoscopic tool (not shown). The lumens  406   b ,  406   c  can receive the first and second tools directly therein, or alternatively, receive tool channels (flexible guides)  410   b ,  410   c  like tool channels  310  described above for angling the endoscopic tools slidably positioned therein.  FIG.  4 D  illustrates the system in the collapsed configuration and  FIG.  4 E  illustrates the system in the expanded configuration. In  FIG.  4 E , the tool channels (flexible guides)  410   b  and  410   c  are shown exposed from the catheter  405  so their distal ends are in a curved position. The tool channels can be further advanced axially to align the curved distal ends with the target tissue. 
     The system  400  also includes retractor elements  451 ,  452 ,  453  and  454 . The retractor system further includes a flexible tube or beam  470  in the collapsed configuration, whereas in the expanded configuration, the retractor system has a rigid beam  475  that was formed from the flexible beam  470 . A rigid beam can be formed from a flexible beam, in some embodiments, by slidably inserting a rigid rod into a flexible tube that composes the flexible beam. More specifically, in this embodiment, the flexible beam  470  slidably receives thereover a stabilizing or rigidifying structure such as a rigid rod. The rigidifying (stabilizing) structure can be independently actuated by the user by actuating a control, such as a slidable lever, operably connected to the rigidifying structure, such that movement of the actuator distally advances the rigidifying structure over the flexible beam  470  to thereby stiffen the beam. Alternatively, the flexible beam  470  can have a lumen to slidably receive therein a rigidifying structure such as a rigid rod. The structure in either version can optionally be retracted from the flexible beam  470  to return the system back to the original more flexible state to aid collapsing of the retractor system. The beam  470  can be substantially circular in cross-section, although other cross-sectional shapes are also contemplated. As in the aforedescribed embodiments, the rigid beam limits deflection of the distal end of the catheter which could otherwise occur by pressure exerted on the distal end by the body lumen wall. 
     In many embodiments, the term “tool channel” can be used interchangeably with the term “working channel “or tool guide.” And, in some embodiments, a channel can be a separate component placed inside the outer tube, or it can be a space remaining in the lumen of the outer tube between separate components that were placed in the outer tube, the separate components including, for example, an endoscope, a working channel, an instrument, a guide, and the like. 
     In some embodiments, as shown for example in  FIGS.  4 A- 4 E , the system can comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor  450  that expands to form a treatment space  460  in the subject. The retractor  450  can be configured, for example, for the expansion to occur distal to the distal end  408  of the outer tube  405 . In some embodiments, the retractor can at least substantially render the target tissue  490  aperistaltic for the treatment. The retractor  450  can have a variety of configurations to serve, for example, as a scaffolding within the gastrointestinal tract  495 . For example, the retractor  450  can include retractor elements  451 , 452 , 453 , 454 , along with a proximal coupler  498  operably connected to the retractor elements  451 , 452 , 453 , 454 , whether at least substantially attached and/or at least slidably-engaged to the retractor elements  451 , 452 , 453 , 454 , and a distal nexus or coupler  499  for a distal point of an operable connection with the retractor elements  451 , 452 , 453 , 454 . Relative movement of the couplers  498 ,  499  can expand the retractor elements as described above. Alternatively, as described above, the retractor elements can be operably attached to a proximal actuator which moves the proximal portions relative to the fixed distal portions to bow the retractor elements outwardly, which in preferred embodiments can be made of superelastic material (although other materials are contemplated), or shape memorized retractor elements can be utilized. 
     The retractor elements  451  and  452  can have a covering  451   a ,  452   a , respectively, which add bulk to the retractor elements  451 ,  452  by increasing its cross-sectional diameter. This is described in more detail below in conjunction with the embodiment of  FIGS.  6 A- 6 D . 
     Moreover, the retractor  450  can be a reversibly-stabilized and reversibly-expandable retractor, the retractor  450  forming an asymmetrical treatment space upon the expansion. And, the retractor  450  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  450 , the arrangement designed to facilitate ease of positioning of the system  400  in the subject and to reversibly stiffen for the expansion of the retractor  450 . The stabilization of the retractor  450  can, in some embodiments, include stabilizing the retractor  450  through a stabilizer subsystem as taught herein, the stabilizer having, for example, an at least substantially-rigid beam  475  to support the expanded retractor  450 . 
       FIGS.  5 A- 5 D  illustrate side and top views of a system as taught herein, having side views and top views of expanded and collapsed configurations, according to some embodiments. The tool channels and tools are omitted for clarity, being similar to those described herein.  FIGS.  5 A and  5 B  illustrates side views of system  500  in collapsed and expanded configurations showing an example of an asymmetric work space that can be formed during an endoscopic procedure using the system  500 . And, as shown in  FIG.  5 B , as with the previously described embodiments, the expansion can occur in a disproportionally greater amount on the luminal side  559  of the rigid beam  575  than the abluminal side  557  of the rigid beam  575  to increase the treatment, or working space  560 , the treatment space  560  having a volume that is asymmetrically distributed around the rigid beam  575 . In some embodiments, the expansion of the various retractors systems disclosed herein can occur in an amount that is at least 5× greater on the luminal side  559  of the rigid beam  575  than the abluminal side  557  of the rigid beam  575 . And in some embodiments, the expansion can be at least 1.1× greater, at least 1.3× greater, at least 1.5× greater, at least 2.0× greater, at least 2.5× greater, at least 3.0× greater, at least 3.5× greater, at least 4.0× greater, at least 4.5× greater, at least 5.0× greater, at least 5.5× greater, at least 6.0× greater, at least 6.5× greater, at least 7.0× greater, at least 7.5× greater, at least 8.0× greater, at least 8.5× greater, at least 9.0× greater, at least 9.5× greater, at least 10.0× greater, or any 0.1× increment within this range, on the luminal side of the beam than the abluminal side of the beam. 
     In some embodiments, as shown for example in  FIGS.  5 A- 5 D , the system can comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor  550  that expands to form a treatment space  560  in the subject. The retractor  550  can be configured, for example, for the expansion to occur distal to the distal end  508  of the outer tube  505 . In some embodiments, the retractor can at least substantially render the target tissue  590  aperistaltic for the treatment. The retractor  550  can have a variety of configurations to serve, for example, as a scaffolding within the gastrointestinal tract  595 . For example, the retractor  550  can include retractor elements  551 , 552 , 553 , 554 , along with a proximal coupler  598  operably connected to the retractor elements  551 , 552 , 553 , 554 , whether at least substantially attached and/or at least slidably-engaged to the retractor elements  551 , 552 , 553 , 554 , and a distal nexus or coupler  599  for a distal point of an operable connection with the retractor elements  551 , 552 , 553 , 554 . The couplers  588 ,  599  can be relatively movable to expand the retractor elements  551 ,  552  (and optionally elements  553 ,  554  in the embodiments where they are expandable) in the same manner as the couplers described above, e.g., couplers  198 ,  199 . The retractor elements can alternatively be fixedly attached at their distal ends, e.g., to distal coupler  599 , and operatively connected at proximal ends to an actuator or made of self-expanding material such as shape memory material as in the various embodiments described herein. Each retractor element  551 ,  552  in the embodiment of  FIG.  5 B  expands to a substantially uniform (symmetric) arcuate shape, although alternatively they each can be configured to expand to a non-uniform (non-symmetric) shape as in the embodiments described above. Note that in this embodiment where the retractor elements  551 ,  552  individually expand to a substantially symmetric shape, there expansion is on one side of the multi lumen outer tube  505 , i.e., to only one side of a longitudinal plane through which a longitudinal axis passes. Therefore, their expansion with respect to the retractor system is asymmetric while their individual expanded shape might be symmetric. Retractor elements  553 ,  554  have a slightly bowed configuration similar to retractor elements  353 ,  354 . Retractor elements  553 ,  554 , positioned as the lower elements of the cage as viewed in the orientation of  FIG.  5 A , can have limited expansion or can be provided so they do not expand when the retractor system expands but instead remain substantially in the same position. In such embodiments, the expanding retractor elements  551 ,  552  can be operably connected to an actuator and the lower elements  553 ,  554  can be fixedly (non-movably) attached to the catheter, e.g., to fixed proximal and distal couplers. Such attachment alternative is also applicable to the other embodiments disclosed herein wherein it is disclosed that the lower retractor elements maintain substantially the same position in the collapsed and expanded positions of the retractor system. 
     Moreover, as with the retractors described hereinabove, the retractor  550  can be a reversibly-stabilized and reversibly-expandable retractor, the retractor  550  forming an asymmetrical treatment space  560  upon the expansion. And, the retractor  550  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  550 , the arrangement designed to facilitate ease of positioning of the system  500  in the subject and to reversibly stiffen for the expansion of the retractor  550 . The stabilization of the retractor  550  can, in some embodiments, include stabilizing the retractor  550  through a stabilizer subsystem as taught herein, the stabilizer having, for example, an at least substantially-rigid beam  575  to support the expanded retractor  550 . In the embodiment of  FIGS.  5 A- 5 D , the rigid beam  575  can be provided in a permanently stiffened condition as beam  175  of  FIG.  1   , or alternatively can be formed by advancement of a rigidifying (stabilizing) structure over a flexible element or into the lumen of the flexible tubular member by an actuator as described above. In either case, the beam rigidifies the retractor system in the asymmetrical configuration creating the stable asymmetrical working space to facilitate access and manipulation of the target tissue. 
       FIGS.  6 A- 6 D  illustrate side views of a system as taught herein having side views and cross-sections of expanded and collapsed configurations of the system, according to some embodiments. The figures illustrate an example of a multi-lumen catheter system having a reversibly-stabilized and reversibly-expandable retractor for a minimally invasive treatment of a subject.  FIGS.  6 A and  6 B  illustrate a side view that shows that the system  600  can include a flexible outer tube  605  for guiding one or more tool channels (not shown) similar to the tool channels described above and an endoscope (not shown) similar to the endoscope described above within the system  600 . The flexible outer tube  605  has a lumen, a proximal end extending into the handle  680 , and a distal end  608 . Each tool channel (serves as a guide through which a tool (not shown) can be manipulated in a treatment of a target tissue in a subject. That is, the tool channels are configured to receive and reorient the tools inserted therethrough as in the embodiments described above. In some embodiments, the retractor  650  can be a reversibly-stabilized and reversibly-expandable retractor  650  forming a treatment space  660  upon expansion and configured for the expansion to occur distal to the distal end  608  of the outer tube  605 . The retractor  650  can be designed to reversibly-stiffen an otherwise flexible arrangement of the retractor  650 , the flexible arrangement designed to facilitate the positioning of the system in the subject and to reversibly-stiffen for the expansion of the retractor  650 . In these embodiments, the reversibly-stiffened arrangement of the retractor  650  can form an at least substantially-rigid beam  675  from an otherwise flexible beam  670  as a structural support for the expansion of the retractor  650 . 
     Handle  680  at the proximal end includes entry ports for operatively combining the system with external components, such as an entry port  609  for an endoscope (not shown) and/or a tool (not shown). The handle  680  is also operatively connected to the proximal end of the outer tube  605  and can have exit ports from the handle  680  into the outer tube  605 . The system can include a stabilizer subsystem, in some embodiments. For example, a stabilizer actuator  612  can be included on the handle  680  to reversibly-stiffen the flexible beam  670  to create the at least substantially-rigid beam  675  for the expansion of the retractor  650 . A retractor actuator  614  can be included on the handle  680  to reversibly expand the retractor  650 . The retractor  650  is shown in  FIGS.  6 A and  6 B  in the collapsed (non-expanded) condition. 
       FIGS.  6 C and  6 D  illustrate oblique views of the system  600  in expanded configurations. The expanded configurations have a rigid beam  675  that was formed from the flexible beam that is typically present in the collapsed state for positioning in the subject. The rigid beam  675  can be formed from a flexible beam, in some embodiments, by slidably inserting a rigid member (e.g., a rod) either over or alternatively into a flexible member that composes the flexible beam to transform the flexible beam into a stiffer, more rigid beam. As shown in  FIGS.  6 B and  6 D , the stabilizer actuator  612  is operably connected to the rigid member (stabilizing structure) such as rigid rod  672  through a rod coupler  613 . Consequently, movement of the actuator  612  in a first direction, e.g., a distal direction from a proximal position, will cause the stabilizing structure  672  to advance over the flexible beam  670  to rigidify it (forming beam  675 ) to stabilize the retractor system, and movement of the actuator  612  in a reverse, e.g., a proximal direction back to its proximal position, will retract the stabilizing structure  672  from the flexible beam  670  to return the flexible beam  670  to its more flexible condition. 
     The retractor actuator  614  is operably connected to retractor elements  651 , 652  through an element coupler  611 . The stabilizer actuator  612  and/or the retractor actuator  614  can be reversibly engageable with the handle  680 , in some embodiments, such that the stabilizer actuator  612  and/or the retractor actuator  614  can be reversibly-fixed in position relative to the handle  680 . In some embodiments, the stabilizer actuator  612  and/or the retractor actuator  614  can be multi-positional, having at least three positions for expansion and/or collapse of the retractor. In some embodiments, the stabilizer actuator  612  and/or the retractor actuator  614  can have a plurality of ratchet teeth  616  to provide a plurality of positions for reversibly-fixing the stabilizer and/or for reversibly fixing the retractor in position during expansion or collapse of the retractor. As shown in  FIG.  6 B , in the proximal position of the retractor actuator  614 , coupler  611  is in the proximal position and the retractor elements are in the non-expanded position. To expand the retractor elements, retractor actuator  614  is slid distally to move the attached coupler  611  distally, as shown in  FIG.  6 D , thereby causing the attached elements  651 ,  652  to bend outwardly due to their fixed connection at their distal end to the distal coupler  699 . 
     One of skill will appreciate that the handle can be any of a variety of shapes to provide a desired or ergonomic position for operation of the system. By way of example, the retractor actuator can be configured as a finger-activated button on the handle  680  that slides back and forth through a slot in the handle  680  to expand or collapse the retractor elements. A means for dynamically adjusting or ratcheting the retractor position can be provided along the handle slot to lock the position of the retractor elements in place when the retractor actuator button is not pressed. A button on the opposite side of the handle can be operatively connected to the stabilizer subsystem to convert the flexible beam into a rigid beam, or convert the rigid beam into a flexible beam. The handle can have inner channels routed axially, for example, within the body of the handle and in communication with ports for tools and endoscope introduction into the outer tube. In some embodiments, the handle can be configured to require that the stabilizer actuator is activated before the retractor actuator can be activated, serving as a “safety” mechanism in the operation of the system. 
     As such, in some embodiments, as shown for example in  FIGS.  6 A- 6 D , the system can comprise a stable, yet dynamic operative environment in that it can include a reversibly-expandable retractor  650  that expands to form a treatment space or working chamber  660  in the subject. The retractor  650  can be configured, for example, for the expansion to occur distal to the distal end  608  of the outer tube  605 . In some embodiments, the retractor can at least substantially render the target tissue  690  aperistaltic for the treatment. The retractor  650  can have a variety of configurations to serve, for example, as a scaffolding within the gastrointestinal tract  695 . For example, the retractor  650  can include retractor elements  651 , 652 , 653 , 654 , along with a proximal coupler  698  operably connected to the retractor elements  651 , 652 , 653 , 654 , whether at least substantially attached and/or at least slidably-engaged to the retractor elements  651 , 652 , 653 , 654 , and a distal nexus or coupler  699  for a distal point of an operable connection with the retractor elements  651 , 652 , 653 , 654 . More specifically, the distal end of the retractor elements  651 ,  652  are attached within slots or openings in the proximal end of the distal coupler  699 . The proximal ends of the retractor elements  651 ,  652  extend proximally through lumens in the catheter to attach to movable coupler  611 . In this manner, with the distal ends of the retractor elements  651 ,  652  fixed, distal movement of the coupler  611  forces retractor elements to bow outwardly as shown. Retractor elements  653 ,  654  can be attached to the distal coupler  699  and in some embodiments attached to movable coupler  611  if some expansion of these retractor elements  653 ,  654  is desired, or alternatively, fixedly attached to the catheter if expansion is not desired and expansion is limited to the retractor elements  651 ,  652 . 
     It should be appreciated, that such couplers for retraction element expansion disclosed in  FIGS.  6 A- 6 D  can be utilized with the other embodiments of the retractor systems disclosed herein. Additionally, it should be appreciated that alternative ways to expand the retractor elements can be utilized, including for example providing relatively movable couplers  698 ,  699  to expand the retractor elements  651 ,  652 , (and optionally  653 ,  654 ) in the same manner as the couplers described above, e.g., couplers  198 ,  199 . The retractor elements can also alternatively be made of self-expanding material such as shape memory material. 
     Each of the retractor elements  651 ,  652  in the embodiment of  FIGS.  6 A- 6 D  expand to a substantially symmetric arcuate shape, although alternatively they can be configured to expand to an asymmetric shape as in the embodiments described above. Note that in in this embodiment where the retractor elements  651 ,  652  expand to a substantially symmetric shape, their expansion is on one side of a longitudinal axis of the multi lumen tube outer tube (catheter)  605 . Therefore, the expansion of the retractor system is asymmetric while their individual expanded shape is substantially symmetric. Retractor elements  653 ,  654  can optionally expand slightly outwardly in a bowed configuration. The retractor element  651  can have a covering thereon. Similarly, retractor element  652  can have a covering thereon. The covering extends over an intermediate portion of the elements  651 ,  652  and can be in the form of a heat shrink tubing. The covering helps control expansion by providing a less flexible region. This covering is similar to covering  451   a  and  452   a  of the embodiment of  FIGS.  4 D,  4 E . 
     As described herein, the retractor  650  can be a reversibly-stabilized and reversibly-expandable retractor, the retractor  650  forming an asymmetrical treatment space  660  upon the expansion. And, the retractor  650  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  650 , the arrangement designed to facilitate ease of positioning of the system  600  in the subject and to reversibly stiffen for the expansion of the retractor  650 . The stabilization of the retractor  650  can, in some embodiments, include a means for stabilizing the retractor  650  through a stabilizer subsystem as taught herein, the stabilizer having, for example, an at least substantially-rigid beam  675  to support the expanded retractor  650 . 
     The rigid rod can be a straight component comprising a rigid material, for example stainless steel or another metal or alloy, that is slidable in and out of the inner diameter (lumen) of the flexible tube. As such, the stabilizer subsystem can have a flexible beam or rigid beam by sliding the rigid rod proximal (i.e., anally) to the flexible tube by pulling back on the rigid rod through a mechanism operably connected to the handle. The rigid rod can be pushed forward (i.e., orally) into the flexible tube to stiffen and straighten the flexible tube as in the embodiments described above. By pushing the rigid rod across the length of the flexible tube, the flexible tube, or flexible beam, becomes rigid and straight, and in effect renders the whole retractor structure at least substantially rigid and straight to stabilize the retractor system. One of skill in the art will appreciate that any mechanism of reversibly stiffening a flexible component in vivo may be used in some embodiments. For example, the flexible tube, or flexible beam, may also comprise a series of rigid tubes having a flexible, non-stretchable cable passing through the lumens of the tubes. When the cable is relaxed, the series of rigid tubes can be separated using, for example, a compressible component such as a spring between each of the series of rigid tubes to provide a flexible non-overlapping configuration. When the cable is tensioned, the compressible components compress, and the rigid tubes overlap, converting the flexible beam into a rigid beam. Such alternative mechanisms can be utilized with any of the embodiments described herein. 
     The reversibly-stabilized retractor, as described herein, is useful in positioning the working space at the site of treatment of the target tissue as it can be rendered flexible for positioning and later rendered rigid for expansion of the retractor. During introduction of a system taught herein into a tortuous body lumen, for example a colon, the retractor can be unexpanded and flexible. This flexibility allows the retractor to bend to conform to the bends in the tortuous body lumen, so that it can be advanced with ease and not cause trauma to the lumen. The rings which hold the retractor elements together can also have lumens that allow passage of a guide such as an endoscope. In such embodiments, when the retractor is in the flexible mode for introduction, for example, the rings can be free to slide over the guide as the system is advanced forward. In some embodiments, the lumens of the rings can be large enough relative to the diameter of the guide to allow for tilting and translation of the system on the guide, helping the system conform to the bends of the guide during advancement of the system orally or anally. Once the retractor is advanced to the target location in the lumen, the flexible beam of the retractor can be straightened and stiffened as described herein. Since the system can be flexible and torsionally stiff, the proximal shaft or the handle can be easily rotated as desired relative to the location of the target lesion. 
     The retractor elements can have at least one pair that is pre-shaped having peaks pointing outwards at a desired angle. In some embodiments, the angle can range from about 45 degrees to about 135 degrees, about 60 degrees to about 120 degrees from each other on one side of the rigid beam, the vertex of the angle being the central axis of the rigid beam, as can be seen in the figures provided herein. In some embodiments, the angle is about 90 degrees between retractor elements. Upon expansion, the retractor elements bulge outwards on one side disproportionally more than the other retractor elements, resulting in an asymmetrical expansion of the retractor. The at least substantially rigid beam prevents or inhibits deformation of the retractor during creation of forces on the retractor in the expansion and prevents or inhibits bending of the catheter tip. The forces include forces from expanding tissue outwards asymmetrically, as well as the initial forces applied on the retractor elements to create an asymmetrical working space. 
     In some embodiments, the target lesion can be located on the side of the most expanded retractor elements so to facilitate maximizing or increasing the distance between the lesion to be treated and the portals at which the endoscope and tools are introduced into the working space. The endoscope and tools can be maneuvered independently, for example, to access the lesion at a greater range of angles than is currently clinically obtainable using state-of-the-art systems. This increased maneuverability can improve the view of the lesion and ability to manipulate and dissect the lesion. For example, a grasper can be advanced out of the instrument channel into the working space and flexed towards the polyp, grasp the polyp and retract the tissue to expose the base of the polyp for dissection by a dissection tool through the multi-channel systems taught herein. Sometimes, it can also be desired to reduce the distance between the lesion to be treated and the portals at which the endoscope and tools are introduced into the working space. For example, it can be desired to locate the lesion on the side of the least expanded retractor elements to better align the lesion with the endoscope channel substantially parallel to the lumen wall. Such a configuration may be clinically optimal while the polyp is retracted by a grasper towards the most expanded side. In such embodiments, a dissection tool can be advanced through a channel at the base of the polyp and dissect the polyp&#39;s base where it attaches to the lumen wall, while the position of the endoscope provides a close view of the base of the polyp to help identify the desired margin for dissection. 
     Any of the systems taught herein can include a bridge member, which provides structural support to add stability to the retractor. The bridge member can include any configuration conceivable by one of skill to provide additional support, such as a scaffolding for enhancing or buttressing the stability and rigidity of the expanded contractor. For example, bridge member  644  is configured to maintain a desired orientation of the retractor elements  651 , 652 , 653 , 654  during the expansion, the bridge member  644  operably stabilizing at least two  651 , 652  of the four retractor elements  651 , 652 , 653 , 654 . As shown, the bridge member outer portion in the collapsed position of the retractor  650  extends radially outwardly and in the expanded position extends more distally (see.  FIG.  6 D ). Although only one bridge member  644  is shown, it is also contemplated that more than one bridge member could be provided to connect retractor elements  651 ,  652 . Additionally, one or more bridge members can be provided to connect retractor elements  653 ,  654  to stabilize and limit side to side movement of these elements as well. Moreover, in some embodiments, each of the systems taught herein can have an outer tube, for example outer tube  605 , that is wire-reinforced, such as mesh, braided, or the like, to provide kink resistance and torqueability to the system, as well as to further facilitate a positioning of the system in the subject. In some embodiments, the bridge member  644  can be configured to reduce drag from surrounding tissue during use. For example, as shown in  FIGS.  6 A and  6 B , the bridge member  644  can be configured to facilitate a movement of the system in a gastrointestinal tract by designing the bridge member  644  to include a forward component  644   a  that is inclined to facilitate forward movement orally, and a reverse component  644   b  that is inclined to facilitate reverse movement anally. 
     The bridge member can be connected to the retractor elements, for example, to maintain a desired orientation of the retractor elements as they expand against a gastrointestinal tissue, for example. As the retractor is expanded, the bridge member is also expanded outward. In some embodiments, the bridge member is operably connected only to the retractor elements that expand the most, for example the retractor elements  651 , 652  in  FIG.  6   , which can be the members that incur the most induced forces on the retractor due to the disproportionate pressure applied to create the asymmetrical working space in the expansion. In some embodiments, the bridge can be designed to flex to prevent the retractor elements from collapsing towards each other or bending away from each other, while also providing some spring or elasticity to the system to comply gently with the tissue. One of skill will appreciate that the bridge member can comprise any suitable material that provides the material characteristics desired. For example, the bridge can be formed from a curved nitinol wire in some embodiments. The ends of the nitinol wires can be connected to the retractor elements using any manufacturing process deemed suitable by one of skill for the in vivo uses taught herein, such process including, for example, tubing connectors, adhesives, or solder. 
       FIG.  7    illustrates a cutaway view of the distal end of the outer tube of a system  700  as taught herein, showing components of the expansion and collapse of the retractor, according to some embodiments. The figure illustrates the distal end  708  of outer tube  705 . The distal end  708  includes a slot guide  755  to control the orientation of an expanding retractor element  751 , as well as a port  754   a  for operably receiving/supporting a lower retractor element  754 . Another slot guide (not shown) can be provided to control the orientation of another retractor element. A lumen  706   c  can be provided to contain a working channel  710   c  for insertion of a tool channel as described above for insertion of working instruments or alternatively for direct insertion of working instruments without a tool channel. The lumen  706  of the outer tube  705  can also be used to guide an endoscope (not shown) through an exit port in distal end  708 . Only a portion of retractor components  751 ,  754 ,  770 , is shown to partially describe the relation between the outer tube  705  and the retractor in some embodiments. The retractor can be configured, for example, for the expansion to occur distal to the distal end  708  of the outer tube  705 . For example, the retractor can include four retractor elements as in the embodiments described above, with retractor elements  751  and  754  shown and the two other retractor elements not shown because of the cutaway view. A proximal coupler  798  is operably connected to the four retractor elements, whether at least substantially attached and/or at least slidably-engaged to the retractor elements. The retractor can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor, the arrangement designed to facilitate ease of positioning of the system  700  in a subject and to reversibly stiffen for the expansion of the retractor in the subject. The stabilization of the retractor can, in some embodiments, include stabilizing the retractor through a stabilizer subsystem as taught herein, the stabilizer having, for example, a flexible beam  770  that can be converted to an at least substantially-rigid beam  775 , by slidably engaging a rigid, or substantially rigid, component  772  as taught herein in operable connection with the flexible beam  770 , to support the expanded retractor. The flexible bean  770  can be stiffened in the manners described herein with respect to the flexible beams of the other embodiments. 
       FIG.  8    illustrates a cutaway view similar to  FIG.  7   , except in this embodiment, a floating channel system is provided. That is,  FIG.  8    shows the distal end of the outer tube of a system as taught herein, in which components of the system can be floating in the outer tube to enhance flexibility for positioning the system in a subject, according to some embodiments. The figure illustrates the distal end  808  of outer tube  805 . The distal end  808  includes a slot guide  855  to control the orientation of an expanding retractor element  851  and an opening  811  for lower retractor element  854 . A second slot guide and a second opening (not shown) are provided to receive respectively another upper and lower retractor element. A lumen  806   c  can be provided to contain a working channel  810   c  which receives a tool channel to guide a working instrument or alternatively directly receives a working instrument. The lumen  806  of the outer tube  805  is used to guide an endoscope  815 . Only a portion of the retractor components  851 ,  854  are shown to partially describe an embodiment of the relation between the outer tube  805  and the retractor. The retractor can be configured, for example, for the expansion to occur distal to the distal end  808  of the outer tube  805 . For example, the retractor can include four retractor elements in the same manner as described above, only two of which are shown (elements  851  and  854 ). A proximal coupler  898  is operably connected to the retractor elements, whether at least substantially attached and/or at least slidably-engaged to the retractor elements. The retractor can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor, the arrangement designed to facilitate ease of positioning of the system  800  in a subject and to reversibly stiffen for the expansion of the retractor in the subject. The stabilization of the retractor can, in some embodiments, include stabilizing the retractor through a stabilizer subsystem as taught herein, the stabilizer having, for example, a flexible beam  870  that can be converted to an at least substantially-rigid beam in any of the manners described herein with respect to the rigidifying of the flexible beam, e.g., slidably engaging a rigid, or substantially rigid, component  872  as taught herein in operable connection with the flexible beam  870 , to support the expanded retractor. As in the other embodiments described herein, an actuator can be utilized which is operably coupled to the rigidifying structure to advance and retract it with respect to the flexible beam  870 . 
     The retractor elements are movable between a collapsed insertion position and an expanded position to form an asymmetric working chamber as in the embodiments described above. 
     During a use of the system  800 , the working channel  810   c  can be a floating channel that is (i) at least substantially attached to the lumen of the outer tube at a first proximal location (not shown) and a first distal location  806   c  and (ii) at least substantially floating in the lumen  806  of the outer tube  805  between the first proximal location (not shown) and the first distal location  806   c . Likewise, during the use of the system  800 , the endoscope  815  can be a floating endoscope  815  that is (iii) at least slidably-attached to the lumen  806  of the outer tube  805  at a second proximal location (not shown) and a second distal location  806   a  and (iv) at least substantially floating in the lumen  806  of the outer tube  805  between the second proximal location (not shown) and second distal location ( 806   a ). And, during the use of the system  800 , the working channel  810   c  and the endoscope  815  also form separate floating components of a floating arrangement that (v) at least substantially increases the flexibility of the system  800  over a second such system having separate lumens for a tool and an endoscope, the separate lumens affixed to the lumen throughout the length of the outer tube between the proximal end and the distal end of the outer tube, the increased flexibility facilitating an ease of positioning the system  800  in the subject for the treatment of the target tissue. In some embodiments, the endoscope  815  can be at least slidably-attached to the distal end  808  of the outer tube  805  by inserting the endoscope  815  through a dedicated port (not shown) for the endoscope  815 , such that the system  800  is configured to be substantially limited to a sliding movement in and out of the distal end  808  of the outer tube  805 . And, in some embodiments, the endoscope  815  can be allowed to also float in a port  806   a  that is substantially larger than the endoscope  815 , providing a sliding motion for the endoscope as well as room for side-to-side movements as well. 
       FIGS.  9 A and  9 B  illustrate side views of working, and/or floating, channels that can be used to guide tools as taught herein, according to some embodiments. As discussed herein, the working channels can have at least a portion of which floats in the lumen of the outer tube in a manner that is the same or similar to  FIG.  8    to further enhance the flexibility of the outer tube during position of the system in a subject. In some embodiments, the terms “channel,” “floating channel”, and “tool channel” can be used interchangeably. Each tool channel can be operatively connected to a handle  980  in a manner that is the same or similar to the operable connections taught herein for the retractor actuator and/or the stabilizer actuator.  FIG.  9 A  shows the tip  910   a  of the tool channel  910  in a substantially extended position, whereas  FIG.  9 B  shows the tip  910   a  of the tool channel  910  in a substantially bent position, such that the distal tip  910   a  is deflected substantially normal to the central axis of the tool channel  910 . A system  900  consistent with other systems taught herein, for example, can include an entry port  909 , a tool channel  91  inserted through entry port  909 , a wire coupler  911 , ratchet teeth  916 , a pull wire  917  for flexing or extending the tip  910   a  of the working channel  910 , and wire actuator  919 . The ability to flex the tip  910   a  of the tool channel  910  facilitates independent positioning of a tool (not shown) in the treatment of a target tissue in a subject. In some embodiments, the wire actuator  919  can be multi-positional, having at least three positions for bending tip  910   a  of tool channel  910 . In some embodiments, the wire actuator  919  can have tooth engageable with one of a plurality of ratchet teeth  916  in handle housing  915  to provide a plurality of positions for reversibly-fixing the bent tip  910   a  in position during use of the tool (not shown) in the treatment of the target tissue in the subject. More specifically, when the wire actuator  919  is moved from its distal position of  FIG.  9 A  to a more proximal position, it pulls pull wire  917 , which is attached to the tip  910   a  of tool channel  910 , proximally to tension the tip  910   a , causing it to bend to the configuration of  FIG.  9 B . Engagement of the tooth of actuator  919  with the teeth  916  maintains the position of actuator  919  and thus maintains the bent position of the tip  910   a . Note although the tip is shown bent at substantially 90 degrees to the longitudinal axis of the tool channel  910 , bending to other angles is also contemplated. Also, in some embodiments, actuator  919  is provided to control the angle of tip  910   a  by controlling the degree of proximal retraction of the pull wire  917 , with further retraction further bending the tip  910   a  and less retraction bending the tip  910   a  to a lesser degree. More than one tool channel can be provided, and the multiple tool channels can be controlled by actuator  919 , or alternatively, a separate actuator  919  can be provided for each tool channel. Also, various mechanisms can be utilized to lock the actuator(s)  919  in position to maintain the bent position of the tip of the tool channels. 
     Other mechanisms can also be utilized to control the tool channels. Alternatively, one or more of the tool channels can have a pre-bent (pre-curved) tip which is substantially straight when in the insertion position within the confines of the multi-lumen tube (catheter) and returns to the pre-bent position when exposed from the confines of the catheter. 
     As described herein, the channels can be configured to control the trajectory and position of instruments such as forceps in the working space created by the retractor. In some embodiments, a channel can be removed from, or inserted through, the outer tube of the system, alone or inside an additional channel that may be used as a guide. The channels can be virtually any size considered by one of skill to be useful in the systems described herein. For example, a channel can have an inner diameter ranging from about 1 mm to about 5 mm, from about 2 mm to about 4 mm, from about 1 mm to about 3 mm, or any range therein. The length of the channel should, of course, complement the length of the system. For example, the channel can have a length ranging from about 40″ to about 72″, from about 48″ to about 60″, from about 42″ to about 70″, from about 44″ to about 68″, or any range therein in increments of 1″. 
     The channels can also comprise any material or configuration known to one of skill to be suitable for the uses described herein. For example, the channels can comprise a single polymer layer, multiple polymer layers, a wire reinforced layer, or a combination thereof. In some embodiments, a channel can comprise (i) an inner layer of a polymer such as, for example TEFLON or polyethylene for slippery luminal surface on the inner diameter of the channel; (ii) a metal such as, for example, a stainless steel, nitinol, or cobalt chromium as a wire reinforcement in the configuration of a braid, mesh, or helical coil layer covering the inner layer; and, (iii) an outer layer of a polymer such as, for example, PEBAX, polyurethane, polyethylene, silicone, PVC, or nylon. 
     In some embodiments, the channels can be configured such that the outer layer (iv) is the most rigid in the proximal section of the channel (i.e., the first about 12″ to about 24″ of the channel), having a hardness of about 60 Shore D to about 80 Shore D; (v) has a medium stiffness in the middle section (i.e., the next about 12″ to about 36″ of the channel), having a hardness of about 50 Shore D to about 72 Shore D; and, (vi) is the most flexible in the distal section (i.e., the next about 0.5″ to about 2″ of the channel), having a hardness of about 20 Shore D to about 50 Shore D). The distal section of the channel can be the section that flexes and can be the distal about 1″ of the channel, in some embodiments. In some embodiments, the channels can have a rigid section just proximal to the distal section to keep this flexible section straight when there is a bending moment on the tip such as when the instrument which is inserted through the channel is grasping a tissue during a gastrointestinal treatment, for example. The length of the rigid section of the channels can range, for example, from about 1 cm to about 10 cm, from about 2 cm to about 8 cm, from about 3 cm to about 7 cm, from about 4 cm to about 6 cm, about 6 cm, or any range therein in 1 cm increments. The rigid section can include a rigid tube comprising a reinforcement material such as, for example, stainless steel or NITINOL, or a polymer such as PEEK or a polyimide embedded between the outer polymer layer and the inner polymer layer. The rigid section can have any suitable length to perform its function in the system. In some embodiments, the rigid section can have a length ranging from about 0.001″ to about 0.005″. 
     The thickness of the inner layer of the channels can range from about 0.0005″ to about 0.005″, from about 0.001″ to about 0.004″, from about 0.002″ to about 0.003″, about 0.001″, or any range therein in 0.0005″ increments. The thickness of the reinforcement layer can range from about 0.001″ to about 0.006,″ from about 0.002″ to about 0.005,″ from about 0.003″ to about 0.005,″ from about 0.001″ to about 0.003,″ about 0.002″, or any range therein in increments of 0.0005″. The thickness of the outer layer can range from about 0.003″ to about 0.012″, from about 0.004″ to about 0.010,″ from about 0.005″ to about 0.009,″ from about 0.005″ to about 0.008,″ about 0.010″, or any range therein in increments of 0.001″. 
     For flexing the distal end of the channel, there can be a side lumen with a pull wire embedded between the inner layer and the outer layer. In some embodiments, the side lumen can be located between the inner layer and the reinforcement layer, or the side lumen can be a part of the inner layer. The side lumen can be made of any material considered by one of skill to be useful in the systems taught herein. For example, the material can include a flexible tube of polymer such as, for example, TEFLON or polyethylene. In some embodiments, the side lumen runs parallel to the length of the channel in the distal section of the channel and then helical proximal to the distal section of the channel. The pitch of the helix can vary, for example, from about 1.0″ to about 6.0″, from about 2.0″ to about 5.0″, from about 1.0″ to about 4.0″, from about 3.0″ to about 5.0″, about 4.0″, or any range therein in 0.1″ increments. By routing the side lumen helically, the wire tension can be distributed all around the shaft so that the shaft can be rotated in any orientation smoothly and remain at least substantially stable. In some embodiments, the pull wire can run from the wire actuator in the handle into the side lumen, out of the distal end of the side lumen, and looped around a rigid ring. The rigid ring (stainless steel, 0.002-0.005″ thick, 0.040″-0.25″ long) at the distal end and back into the side lumen and out into the handle and attached to the wire actuator. The handle can be operatively connected to the channel, the handle having a housing, and a lumen in communication with the channel. The wire actuator is operatively attached to the pull-wire inside the housing with a button on the outside of the handle allowing the wire actuator to slide back (proximal) and forth (distal) on the handle to pull and push the pull-wire. Pulling the wire makes the tip flex and become rigid, whereas pushing the wire can make the tip relax and straighten. The slide has a means for locking the wire actuator in place, for example, using complementary ratchet teeth on the housing and wire actuator mechanism. When the wire actuator button is pressed, the ratchet teeth can disengage and unlock the pull-wire. In some embodiments, the tip can flex from about 0 degrees to about 150 degrees. In another embodiment, the tip can flexed from about 45 degrees to about 100 degrees. The can be designed to be flexible in bending but stiff in torsion, allowing the channel to follow the curvatures of the anatomy and allow for a rotation of the handle from outside the body during use, transmitting torque to rotate the tip to a desired direction. 
     The tool (working) channels positioned inside the outer tube provide a multi-lumen catheter having manipulable passages for independently manipulating tools from outside the body into the working space inside created by expansion of the retractor. In some embodiments, from 1 to 3 flexible tubes run inside of the outer tube and can be detached from the outer tube, as described herein, which facilitates the flexibility of the system. In some embodiments, these flexible tubes can be attached at two points: (i) the proximal coupler of the retractor, which can be a ring-type structure having ports at the distal end of the outer tube, and (ii) at the proximal end of the shaft, such as at the handle. This can provide a floating arrangement in the outer tube that is unique, constraining the ends of the flexible tubes while allowing for a substantially free-floating movement of the flexible tubes in the outer tube to enhance the flexibility of the system. 
     In some embodiments, 2 inner tubes can be positioned adjacent to the inner surface of the outer tube to provide, effectively, 3 separate channels. The 2 inner tubes can function as 2 independent tool channels while the space between these first 2 channels and the outer tube functions as a third channel. The third channel can be substantially larger than the other 2 channels. Each of the first 2 tool channels can have, for example, an inner diameter ranging from about 2 mm to about 6 mm, about 3 mm to about 5 mm, or any range therein. In some embodiments, the diameter of the first 2 tool channels can be about 4 mm. Each of the channels can be designed to accommodate an endoscope such as a colonoscope, as well as endoscopic tools that include, for example, forceps, graspers, clip applier, dissectors, snares, electrical surgical probes, or loops. In some embodiments, the largest diameter channel can be the channel for the endoscope. 
     The channel for accommodating the endoscope can be designed to have an inner diameter, for example, ranging from about 5 mm to about 15 mm, from about 6 mm to about 12 mm, from about 11 mm to about 14 mm, from about 5 mm to about 10 mm, from about 8 mm to about 13 mm, or any range therein in 1 mm increments. The inner tubes can comprise any suitable material known to one of skill to be useful for the purposes set-forth herein, as well as composites thereof. For example, the inner tubes can comprise a fluoropolymer such as TEFLON for lubricity to ease tool or endoscope passage and movements. Other materials that may be used include, for example, polyethylene, polypropylene, PEBAX, nylon, polyurethane, silicone, and composites thereof, each of which may also be used with a lubricant coating. The tubes may also comprise a metallic wire reinforcement such as a braid, mesh or helical coil, each of which may be embedded in the tube. 
     One of skill should appreciate that the systems taught herein can be used as a surgical suite with a floating, multi-lumen-catheter retractor system having a reversibly-stabilized and reversibly-expandable retractor for a minimally invasive treatment of a subject. In these embodiments, the system can comprise a flexible outer tube for guiding a floating channel and a floating endoscope in a substantially floating arrangement within the system. Due to the construction of the floating system, the system is highly flexible, such that the flexible outer tube can be highly flexible and have a lumen, a proximal end, and a distal end; and, the floating channel can serve as a guide through which a tool is manipulated in a treatment of a target tissue in a subject. The retractor can be a reversibly-stabilized and reversibly-expandable retractor forming a treatment space upon expansion. The retractor can be configured, for example, for the expansion to occur distal to the distal end of the outer tube and to reversibly stiffen an otherwise flexible arrangement of the retractor, the flexible arrangement designed to facilitate the positioning of the system in the subject and to reversibly stiffen for the expansion of the retractor. That is, the system can include a stabilizing/rigidifying structure as in the embodiments described above, which can be slidable to rigidify the element and retractor system. 
     During a use of the system, the floating channel can be (i) at least slidably-attached to the lumen of the outer tube at a first proximal location and a first distal location and (ii) at least substantially floating in the lumen of the outer tube between the first proximal location and the first distal location. Likewise, during the use of the system, the floating endoscope can be (iii) at least slidably-attached to the lumen of the outer tube at a second proximal location and a second distal location; and, (iv) at least substantially floating in the lumen of the outer tube between the second proximal location and second distal location. And, during the use of the system, the floating arrangement can (v) at least substantially increase the flexibility of the system over a second such system having lumens for a tool and an endoscope, the lumens affixed to the lumen of the outer tube throughout the length between the proximal end and the distal end of the outer tube. The increased flexibility can facilitate an ease of positioning of the system in the subject; and, the reversibly-stiffened arrangement of the retractor can form an at least substantially rigid beam as a structural support for the expansion in the subject for the treatment of the target tissue. 
     In some embodiments, the retractor comprises at least two expandable retractor elements, each of the members having a proximal end and a distal end, the proximal end slidably engaged with the outer tube, and each of the members configured such that an increase in the amount of sliding of the proximal end toward the distal end compresses the member and expands the retractor. These embodiments can also include a distal nexus or coupler located distal to the distal end of the outer tube and at which the distal end of each of the at least two retractor elements is affixed; and, a stabilizer subsystem connecting the distal nexus to the distal end of the outer tube and having an at least substantially rigid component configured to reversibly stiffen an otherwise flexible portion of the retractor for an asymmetric expansion of the retractor. 
     In some embodiments, the retractor comprises four expandable retractor elements, each of the members having a proximal end and a distal end, the proximal end slidably engaged with the outer tube, and each of the members configured such that an increase in the amount of sliding of the proximal end toward the distal end compresses the member and expands the retractor. These embodiments can also include a proximal coupler attached to the distal end of the outer tube, the proximal coupler having four retractor ports for the slidable engagement with the four retractor elements, the four retractor ports positioned circumferentially around the proximal coupler and configured to facilitate a reversible, axial sliding of the retractor elements for the asymmetric expansion of the retractor. These embodiments can also include a distal nexus or coupler located distal to the distal end of the outer tube and at which the distal ends of each of the four retractor elements are affixed; and, a stabilizer subsystem connecting the distal nexus to the distal end of the outer tube and having (i) a flexible component that extends from the proximal coupler to the distal nexus and (ii) an at least substantially rigid component that is slidably engaged with the proximal coupler and reversibly extends from the proximal coupler to the distal nexus to reversibly-stiffen the retractor in an asymmetric expansion of the retractor. The retractor elements can be moved to the expanded position in any of the ways discussed above. Also, if desired, only two of the retractor elements expand as in the embodiments described above. 
     The flexible component and the rigid component can have central axes that are each at least substantially parallel to the central axis of the distal end of the shaft, the rigid component forming an at least substantially rigid beam as a structural support for the asymmetric expansion, the rigid beam having a luminal side and an abluminal side. 
     The systems provided herein can be used in several different methods of treatment. For example, the systems can be used in a method of treating a gastrointestinal lesion using a multidirectional and multi-angular approach to the lesion. The method can include positioning the system in a subject&#39;s gastrointestinal tract, the positioning including placing the retractor in proximity to a target lesion for a treatment; expanding the retractor to create the treatment space for use of the tool; treating the lesion with the tool; collapsing the retractor; and, withdrawing the system from the subject. The lesion can include, for example, a perforation, a tissue pathology a polyp, a tumor, a cancerous tissue, a bleed, a diverticuli, an ulcer, an abnormal vessel, or an appendix. 
     It should be appreciated that there are a number of procedures and variations, in addition to those taught above, that can be used readily by one of skill in the implementation of the systems taught herein. In some embodiments, one of skill can insert the endoscope through the endoscope channel of the system and extend the distal end of the endoscope distal to the distal end of the retractor to form an assembly. The assembly can then be inserted into a body lumen or orifice, such as the colon, and advanced orally until the distal end of the scope or the lens is in proximity to the target tissue (lesion or defect) to be treated. The system can then be advanced forward over the scope until the retractor is positioned over the distal end of the endoscope while observing the image from the endoscope. The system can be advanced until the target tissue is located between the proximal coupler and distal nexus of the retractor while observing the image from the endoscope. The handle or outer tube can be rotated to rotate the retractor so that the target tissue is at the desired position relative to the retractor members while observing the image from the endoscope. The retractor can then be straightened and stabilized by converting the flexible beam to a rigid beam. The retractor can then be expanded by moving the retraction actuator forward on the handle while observing the image from the endoscope. This action pushes the tissue outwards, creates a working space around the target tissue, and anchors and stabilizes the target tissue. Optionally, while the retractor is expanded, the system can be pulled back to shift the peak of the most expanded members distally to improve working distance between the endoscope and the peak of the asymmetric work space, wherein the peak is generally recommended to be located around the target tissue. With the instruments inserted into the working (tool) channels, insert the working channels into the proximal ports of the system and advance the instruments and channels distally until the tips of the working channels are distal to proximal coupler of the retractor while observing the image from the endoscope. At this time, the tips of the working channels can be flexed to the appropriate angulation for the tools to approach the lesion to be treated. The working channels can be rotated and moved axially as needed to the desired position for the tools. Likewise, the instruments/tools can be advanced relative to the distal end of the working channels as needed to extend the instruments as needed to reach the target tissue. Various instruments can be inserted through the working channels as desired, and both the endoscope and the instruments can be advanced and positioned independently into the working area to further manipulate and visualize the target tissue at closer proximities or angulations. This is because, in some embodiments, the endoscope can also flex within the working space. 
     In some embodiments, it&#39;s desirable to provide for delivering a system taught herein with an optional cover, or sheath that covers a portion of the system, including the retractor, during delivery of the retractor to a target site, during a treatment of a target tissue at the target site, during a removal of the target tissue, and/or during a removal of the system from the subject, or a combination thereof. Recall that some embodiments of such an optional cover  355  have been illustrated herein, for example, in  FIGS.  3 A and  3 K . One of skill will appreciate that the retractor has elements that can catch, snag, or otherwise disturb or contact tissue during delivery, or removal, of the retractor to or from the target site. Also, the treatment of the target tissue may include, for example a dissection of tissue that can be performed within the cover without intermingling the target tissue with the surrounding tissues. Moreover, the dissected tissue may be a cancerous or other tissue that is desirable to contain during treatment or removal by encapsulating it within the cover. The terms “cover” and “sheath” can be used interchangeably in many embodiments, and one of skill can appreciate that such embodiments are open to improvements, as taught herein. 
       FIGS.  10 A- 10 E  illustrate a retractor sheath covering a retractor of a system as taught herein, according to some embodiments.  FIGS.  10 A- 10 C  show top, oblique, and side-views showing a flexible, clear sheath  1000  that covers a collapsed configuration of the retractor  1050  to render an at least substantially smooth and/or atraumatic surface  1005  for a delivery of the retractor  1050  to a target site (not shown) for a treatment of a target tissue (not shown). In  FIGS.  10 A- 10 C , the cover is in a closed configuration that can be sustained until the expansion of the retractor  1050  for the treatment, or it can be reversibly-obtained following the treatment.  FIGS.  10 D and  10 E  show a top-view and side-view of an expanded configuration of the retractor with the cover in an open configuration for the treatment. 
     The sheath  1000  can be designed to prevent or inhibit the retractor elements  1051 , 1052 , 1053 , 1054  and bridge members  1044   a ,  1044   b  from catching, snagging, or otherwise disturbing or contacting tissue during a delivery or removal of the retractor  1050  to or from the target site. The sheath  1000  is attached at one end to the distal hub or coupler  1099  and extends proximally past the proximal coupler or hub  1098  and is attached to the outer surface of the catheter  1055 . Alternatively, the sheath  100  can be attached at a proximal end to proximal coupler  1098 . Retainers can be used at any position around the retractor to facilitate a retention of the configuration of the working space  1060 , for example, to retain the configuration under forces of the expansion of the retractor  1050 . During the procedure the sheath  1000  can also prevent or inhibit tissue from entering the retractor  1050  until desired. The sheath  1000  can also act as a collection means for entrapping and/or pulling out a resected tissue, which can be particularly desirable in the resection of cancerous tissue in some embodiments. The sheath  1000  can be at least substantially closed around the retractor  1050  during delivery, and can be designed to open as the retractor  1050  is expanded to create the working space  1060  for the treatment. Alternatively, the expansion of the retractor elements and the sheath can be independent. 
     A flexible beam  1070  can be converted to the at least substantially rigid beam  1075  using the methods and structure of conversion as described above in conjunction with the other embodiments. For example, an actuator can be operably connected to the beam (rigidifying structure)  1075  to advance it into a lumen of the flexible beam  1070 , or alternatively advance it over the flexible beam  1070  (as shown in  FIG.  10 D ), to stiffen (make more rigid) the flexible beam  1070 . The bridge member  1044   a  can connect the expandable retractor elements  1051 ,  1052  and bridge member  1044   b  can connect elements  1053 ,  1054  to restrict lateral movement and stabilize the retractor as in the other bridge members described herein. In alternate embodiments, bridge member  1044   b  extends from bridge member  1044   a  and connects to elements  1053 ,  1054  such that all four elements  1051 ,  1052 ,  1053  and  1054  are connected by the bridge elements  1044   a ,  1044   b . Bridge member  1044   c  can connect elements  1053 ,  1054 . 
     Coverings  1051   a  and  1052   a  can be applied to the retractor elements  1051 ,  1052 , respectively, to control expansion as described in the embodiment of  FIG.  11    below. 
     In some embodiments, the sheath  1000  can be perforated longitudinally (not shown), designed such that the sheath  1000  opens upon expansion of the retractor  1050  through tearing of the perforation at the target site. In some embodiments, a tongue-and-groove mechanism, for example a ZIPLOCK mechanism, can be used to at least substantially close a slit  1007  at the top of the retractor  1050  which can also open upon the expansion of the retractor  1050  at the target site. In some embodiments, a larger perforation, or unclosed portion  1001 , can remain in the sheath  1000  to facilitate the tearing or opening of the sheath at the target site upon the expansion of the retractor  1050 . In some embodiments, the terms “slit” and “opening” can be used interchangeably. 
     In some embodiments, the sheath can be reversibly opened, such that the sheath can be re-closable. For example, a drawstring, cable, or wire, can be operably positioned in communication with the opening for the re-closing of the opening by pulling or pushing the drawstring, cable, or wire from outside the patient during the treatment. In some embodiments, the edges of the opening can form longitudinal pockets or channels for pulling or pushing the drawstring, cable, or wire as desired from outside the patient during the treatment, such as by routing the drawstring, cable, or wire through the system and, perhaps, through the handle as with the other actuation means. In some embodiments, a drawstring is used to re-close the sheath, wherein the strings can be tensioned at the handle to close the slit, or loosened to allow the retractor to expand. In some embodiments, the sheath has a stiffening strip running transversely around the mid portion of the cage to facilitate the cage wires expanding without catching on the surrounding sheath. The stiffening strip can be another layer of the sheath welded or glued onto the existing sheath. It can also be formed as a thickened area. Alternatively, a stiffer material can be inserted in the pocket running transversely. The stiffening material may be the same as that of the sheath or it may be a stiffer material. 
     One of skill will appreciate that any of the known materials and/or methods of covering the sheath may be useful for the purposes taught herein. For example, the sheath can range from about 10 mm to about 30 mm at the ends that are attached to the proximal coupler and distal nexus, each of which can be used to define the ends of the retractor  1050 . Moreover, the sheath can be heat welded, glued, or heat-shrunk to the proximal coupler and/or distal nexus, or perhaps substantially proximal or distal to these components, to fasten the sheath to the retractor. In some embodiments, the sheath may even cover the system as a sterilizing, or clean, cover, such that the sheath is an extension of a disposable and/or replaceable component that may be applied, for example, in a sterilization process. And, in some embodiments, the sheath can be larger at the mid portion where the diameter can range, for example, from about 20 mm to about 40 mm in a closed configuration. The sheath can be, for example, opaque, translucent, or clear, and the material composing the sheath can be, for example, a polyethylene, nylon, fluorinated ethylene propylene (FEP), TEFLON, polyethylene terephthalate (PET), or polycarbonate. And, in some embodiments, the sheath material can range, for example, from about 0.0010″ to about 0.0060″ thick, from about 0.0020 to about 0.0080″ thick, from about 0.0030″ to about 0.0050″ thick, from about 0.0010″ to about 0.0030″ thick, from about 0.0005″ to about 0.0100″ thick, about 0.0020″ thick, or any range therein in about 0.0005″ increments. 
     In use, when the retractor system  1050  is moved from the collapsed insertion position of  FIG.  10 B  to the expanded position of  FIG.  10 E , the expandable retractor elements are expanded away from the sheath  1000 . The sheath  1000  can remain open at a surface facing the target tissue to be treated, e.g., removed, from the patient&#39;s body. Alternatively, the sheath  1000  can remain closed and be opened by an endoscopic tool to receive the removed lesion. Note as shown in  FIG.  10 E , in the expanded position, the sheath  1000  is covering the retractor elements  1053 ,  1054  and rigid beam  1075  and is spaced from expanded elements  1051 ,  1052 . In alternate embodiments, the sheath can also cover elements  1051 ,  1052  in their expanded configuration. 
       FIGS.  11 - 30    illustrate alternative embodiments of the system, designated generally by reference numeral  1100 . System  1100  includes a multi-lumen catheter or tubular member  1110  configured to receive one or more tool channels or flexible instrument guides.  FIG.  11    shows two tool channels  1122  and  1124 , it being understood that in some embodiments, only one tool channel can be utilized and in other embodiments more than two tool channels can be utilized, with the catheter provided with a sufficient number of lumens. The tool channels  1122 ,  1124  can be packaged as a kit with the catheter  1110  as shown in  FIG.  11   . Alternatively, the tool channels  1122 ,  1124  can be packaged separately. In other embodiments, the tool channels are packaged already inside the lumens of the catheter  1110 . Each tool channel  1122 ,  1124  has a lumen (channel) to receive an endoscopic instrument (tool) therethrough. 
     The tool channels (also referred to herein as flexible tubes or flexible guides)  1122  and  1124  are inserted through the proximal end of the catheter  1110  and advanced through respective lumens  1112 ,  1114  in the catheter  1110  (see  FIG.  12   ). As shown in  FIG.  16   , which illustrates a proximal portion  1113  of catheter  1110 , the catheter  1110  can include ports  1115 ,  1117 , cooperating with the lumens  1112 ,  1114 , respectively (see e.g.  FIG.  13   ), which can include valves to maintain insufflation when the tool channels  1122 ,  1124  are inserted therethrough and translated axially therein. Tool channel (tube)  1122  preferably has a pre-bent tip  1122   a , best shown in  FIGS.  11  and  18   , to provide a curved distal end. Tool channel (tube)  1124  also preferably has a pre-bent tip  1124   a , providing a curved distal end. When the tool channels  1122 ,  1124  are inserted into the lumens  1112 ,  1114  of catheter  1110 , the tips  1122   a ,  1124   a  are preferably substantially straightened to facilitate advancement through the lumens. When the tool channels  1122 ,  1124  are advanced sufficiently distally so the distal tips  1122   a ,  1124   a  are exposed from the confines of the walls of the catheter lumens  1112 ,  1114 , the tips  1122   a ,  1124   a , return to the pre-set curved position. This can be understood with reference to  FIG.  18    which illustrates in phantom the straightened position of the tool channels  1122 ,  1124  for movement within the catheter  1110 . As in the other embodiments disclosed herein, the tool channels  1122 ,  1124  can be composed of superelastic material, although other materials to provide the curved tip which returns from a substantially straight insertion shape to a curved shape when exposed can also be used, such as stainless steel. Also, as in the other embodiments disclosed herein, shape memory properties of material such as Nitinol can be used with a memorized curved tip shape. In alternative embodiments as described above, the tool channels  1122 ,  1124  can have a mechanism such as a pull wire which is actuated to bend its distal end. The tool channels  1122 ,  1124  in the embodiments of  FIGS.  11 - 30    are unattached to the catheter  1110  so that the user can freely control their axial movement from a proximal end portion  1122   b ,  1124   b , during use. However, it is also contemplated that in alternate embodiments the tool channels can be attached to the catheter. 
     The tool channels  1122 ,  1124  can optionally include markings  1123 ,  1125 , respectively, at a region proximal to the catheter  1110  to provide a visual indicator to the user of the depth of insertion of the tool channels  1122 ,  1124  through the catheter lumens  1112 ,  1114 . The tool channels  1122 ,  1124  can have a luer fitting  1127 ,  1129 , respectively, ( FIGS.  11  and  19 A ) with a valve, at the proximal end which can close off backflow of insufflation gas from the body. This maintains insufflation when the endoscopic tool is inserted through the tool channels  1122 ,  1124  as described below. The tool channels in an alternate embodiment shown in  FIG.  19 B  have a hemostatic valve  1121 A,  1121 B connected at a proximal end of tool channels  1122 ′,  1124 ′, respectively, to maintain insufflation during tool insertion. As shown, valves  1121 A,  1121 B are proximal of luer fittings  1127 ′,  1129 ′. The tool channels  1124 ′,  1126 ′ are identical to tool channels  1124 ,  1126  in all other respects. 
     In one embodiment, the tool channels  1122 ,  1124  can be composed of a flexible soft material, such as Pebax. A superelastic nitinol backbone can in some embodiments be embedded in the wall of the Pebax material, e.g., within the curved portion. Other materials are also contemplated. 
     Catheter  1110  also preferably has a lumen  1116  (see e.g.,  FIG.  16   ) configured and dimensioned to receive an endoscope  1200 . In some embodiments, the lumen  1116  is dimensioned to receive a conventional endoscope, e.g., a conventional colonoscope, and the catheter  1110  is backloaded over the endoscope. This is described in more detail below in conjunction with the method of use. In alternate embodiments, the lumen  1116  can receive an articulating endoscope. Moreover, in alternate embodiments, the endoscope can be inserted into the catheter and inserted into the body lumen. 
     With reference to  FIGS.  11  and  16   , catheter  1110  includes a handle housing  1130  at the proximal portion  1113  which contains two actuators: actuator  1132  for controlling movement of the retractor system  1150  and actuator  1134  for controlling movement of the rigidifying (stabilizing) structure. These are discussed in more detail below. Catheter  1110  also includes tubing  1139  having a luer coupling  1137  and a control switch  1175  (see  FIGS.  31 A,  31 B ) for closing off an internal gasket  1176 . The string, e.g., suture,  1172  for closing covering  1170  is secured by the elastomeric gasket  1176  as the switch  1174  is moved from the position of  FIG.  31 A  to the position of  FIG.  31 B . More particularly, in the initial position of  FIG.  31 A , the ball valve  1174 , seated in a slot in the housing  1179 , does not apply a force to the gasket  1176 . This enables the suture  1172  to freely move within the lumen of the catheter. When it is desired to lock the suture  1172  in position, i.e., after the suture  1172  is tensioned to close the covering  1170 , the switch  1175  is slid forward, thereby camming the ball  1174  downwardly (as viewed in the orientation of  FIG.  31 B ) to collapse the lumen in the gasket  1176  against the suture  1172  to thereby secure the suture  1172 . This locks the suture  1172  against movement which thereby maintains the covering (bag) in the closed position encapsulating the target tissue as described herein. Note that the reverse movement of the switch  1175  unlocks the suture  1172  to enable free movement of the suture  1172 . Catheter  1110  also has tubing  1136  having a one-way stopcock  1138  to provide an insufflation port. This port can be used to supplement the insufflation gas provided by the endoscope  1200 . The insufflation gas flows through lumen  1116  in the area around the endoscope  1200  since the cross sectional dimension of the lumen  1116  exceeds the cross-sectional dimension of the endoscope  1200  to leave a sufficient gap. As shown, the tubings  1139 ,  1136  are positioned distal of the actuators  1132 ,  1134 , 
     Turning now to the retractor system  1150 , which forms a working space expanding system, and in certain clinical applications, a body lumen reshaping or reconfiguring system, and with initial reference to  FIG.  13   , the retractor system  1150  is positioned at the distal portion  1111  of the catheter  1110  (distal of proximal hub  1140 ) and includes flexible retractor elements  1152  and  1154 . Retractor system also includes retractor elements  1156  and  1158 . Retractor elements  1152 ,  1154  form the expandable elements which create the working chamber (space) within the body lumen and form an asymmetric cage. Retractor elements  1156 ,  1158  form the base of the retractor system, thus helping to define the retractor cage along with elements  1152 ,  1154 . In some embodiments, retractor elements  1156 ,  1158  do not undergo any change when the retractor system  1150  moves from the collapsed insertion position to the expanded position; in other embodiments, retractor elements  1156 ,  1158  undergo a slight change in position, i.e., slight expansion or bowing, when the retractor system  1150  is expanded. Retractor elements  1152 ,  1154 , are expandable to form an asymmetric working chamber to improve visibility and working space as described in detail above with respect to the other systems forming asymmetrical working spaces. 
     As shown by comparing  FIGS.  15  and  21 A , retractor elements  1152  and  1154  move from a collapsed insertion position wherein they preferably do not extend beyond, or significantly beyond, the transverse dimension of the catheter  1110  to an expanded position wherein they bow laterally outwardly and have a transverse dimension extending beyond the transverse dimension of the catheter  1110 . Also by comparing  FIGS.  15  and  21 A , it can be seen that lower (as viewed in the orientation of these figures) elements  1156 ,  1158  in the collapsed position do not extend beyond, or significantly beyond, the transverse dimension of the catheter  1110  and when the retractor is expanded, remain substantially in the same position so they still do not extend beyond, or significantly beyond, the transverse dimension of the catheter  1110 . In some embodiments, the elements  1156 ,  1158  do not extend at all beyond the transverse dimension of the catheter  1110 . As in the embodiments described above, the retractor system  1150 , i.e., the retractor elements  1152 ,  1154 , expand to only one side of a plane passing through a longitudinal axis of the catheter  1110 , thereby creating the asymmetric working space  1151  (and asymmetric cage), with its attendant advantages described herein. 
     Retractor elements  1152 ,  1154  have a bridge member  1155  to add stability to the retractor and maintain a desired orientation of the retractor elements during the expansion. The bridge member  1155  is attached to the two retractor elements  1152 ,  1154 , preferably at an intermediate portion, to create a transverse structure for the elements  1152 ,  1154 , limiting side-to side movement. As shown, bridge member  1155  has a first arm  1155   a  connected to retractor element  1152  and a second arm  1155   b  connected to retractor element  1154 . The upper surface (as viewed in the orientation of  FIG.  15   ) can be arcuate as shown. The bridge member  1155  can be a separate component attached to the retractor elements by tubular elements  1159   a ,  1159   b , which are fitted over and attached to retractor elements  1152 ,  1154 , respectively. In this version, the tubular element  1159   a ,  1159   b  has a first opening to receive the retractor element and a second opening to receive an arm of the bridge member, although alternatively they can both be received in the same opening. Note the tubular elements  1159   a ,  1159   b  also bulk up the diameter of the retractor elements  1152 ,  1154  since in some embodiments the retractor elements  1152 ,  1154  are about 0.035 inches in diameter (although other dimensions are contemplated). Other methods of attachment of the bridge members are also contemplated. Alternately, the bridge member  1155  can be integrally formed with one or both of the retractor elements  1152 ,  1154 . The bridge member  1155  can be composed of a material similar to the elements  1152 ,  1154  or can be composed of a different material. The bridge member  1155  can also include legs  1155   d  and  1155   e  which are connected to lower elements  1158 ,  1156 , respectively, to attach the bridge member to lower elements  1158 ,  1156 , respectively, to add to the stability of the retractor system. These leg members  1155   d ,  1155   e  are preferably composed of soft elastomeric material such as polyurethane tubing to add more structure to the cage and facilitate expansion of the cage in a more predictable fashion. 
     Additional bridge members (not shown) can be provided on the retractor elements  1052 ,  1054  to increase stability. The bridge member  1055  can, in some embodiments, in the collapsed position, extend substantially axially as in  FIGS.  15  and  17 A , but change to angle inwardly (downwardly) toward the longitudinal axis of the catheter  1010  in the expanded position of the retractor elements  1052 ,  1054  such as in  FIG.  21 A . 
     An additional bridge member  1157  (or alternatively multiple bridge members) extends between the two lower (as viewed in orientation of  FIG.  15   ) retractor elements  1156 ,  1158 . These elements  1156 ,  1158  can help open up the lower section of the retractor system  1150  and help form the cage for the working space, and the bridge member(s)  1157  can help to stabilize these elements  1156 ,  1158 , e.g., limit side to side movement. The bridge member  1157  as shown has arms  1157   a ,  1157   b  connecting to elements  1156 ,  1158 , respectively. The bridge member  1057  can be a separate component attached to the retractor elements by tubular elements  1161   a ,  1161   b  which are fitted over and attached to retractor elements  1156 ,  1158 , respectively. The tubular elements  1161   a ,  1161   b  can have a first opening to receive the element  1156  or  1158  and a second opening to receive an arm of the bridge member  1157 , although alternatively they can both be received in the same opening. Other ways of attaching the bridge member(s) are also contemplated. Alternatively, the bridge member  1157  can be integrally formed with one or both of the retractor elements  1156 ,  1158 . The bridge member  1157  can be composed of a material similar to the elements  1156 ,  1158  or can be composed of a different material. 
     Additional bridge members (not shown) can be provided on the retractor elements  1156 ,  1158  to increase stability. The bridge member  1157  can, in some embodiments, in the collapsed position, be substantially parallel with a longitudinal axis of the catheter  1110  or extend substantially axially such as in  FIG.  15   , and substantially remain in this position in the expanded position of the retractor elements  1152 ,  1154  as in  FIG.  21 A  since in this embodiment, the retractor elements  1156 ,  1158  remain in substantially the same position when the retractor system  1150  is expanded 
     The catheter  1110  includes a proximal coupler (cap)  1140  through which the retractor elements extend. Handle housing  1130  includes a longitudinally extending slot  1131  ( FIG.  16   ) along which retractor actuator  1132  axially slides. The retractor elements  1152 ,  1154  are coupled to the actuator  1132  via block  1146 , shown in  FIGS.  20 A and  20 B . That is, each retractor element  1152 ,  1152  has a proximal extension that extends through the respective lumen  1112 ,  1114  in the catheter  1150  and is connected at its proximal end to the block  1146 . In this manner, when the actuator  1132  is moved along axial slot  1131  from its proximal position of  FIG.  20 A  to its distal position of  FIG.  20 B , the block  1146  is moved distally, thereby forcing the retractor elements  1152 ,  1154  laterally outwardly since the elements  1152 ,  1154  are fixedly attached to the distal coupler  1148  at their distal ends. Elements  1156 ,  1158  in this embodiment, are fixedly attached to the distal coupler  1148  at their distal ends, and fixedly attached to the proximal coupler  1140  (or other portion of the catheter  1110 ) at their proximal ends such that movement of actuator  1132  does not effect movement of these elements  1156 ,  1158 . It should be appreciated, however, that if it is desired to have the elements  1156 ,  1158  move, e.g., flex slightly outwardly when the retractor  1150  is expanded, these elements  1156 ,  1158  can be attached to the block  1146  so they would be moved when actuator  1132  is advanced, or alternatively attached to a separate actuator. In one embodiment, the elements  1152 ,  1154 ,  1156  and  1158  can be fixed within slots formed in the distal coupler  1148 . Note the proximal and distal couplers  1140 ,  1148  can have openings dimensioned to receive an endoscope when the catheter  1110  is backloaded over the endo scope as described below. Housing  1130  can include a plurality of teeth (not shown) similar to the teeth of  FIGS.  6 A- 6 D  for engagement by a tooth coupled to the actuator  1132 , thereby forming a retaining or locking mechanism to retain the retractor elements in one of several select positions. A release mechanism for the retaining or locking mechanism can be provided. 
     Additionally, it should be appreciated that alternative ways to expand the retractor elements can be utilized, including for example providing relatively movable couplers  1140 ,  1148  to expand the retractor elements  1152 ,  1154  (and optionally  1156 ,  1158 ) in the same manner as the couplers described above, e.g., couplers  198 ,  199 . The retractor elements can also alternatively be made of self-expanding material, such as shape memory material, which expand when exposed from the catheter or sheath. 
     Retractor elements  1152 ,  1154  can optionally have a small crimp forming a flattened position at a distal end adjacent where they are anchored to the distal coupler  1148 . This reduces the bending stiffness at the point so it acts like a hinge to create a more predictable direction of expansion, e.g., to deflect upwardly and slightly outwardly. This also decreases the amount of force required to initiate the bending. Such flattened portion can also be used with the retractor elements of the other embodiments disclosed herein. 
     The retractor system  1150  can be configured to reversibly stiffen an otherwise flexible arrangement of the retractor  1150 . In this regard, retractor system  1150  can include a substantially-rigid beam to support the expanded retractor  1150  which helps to create a more stabilized chamber (or cage) as described herein. With reference to  FIGS.  15  and  17 A , a flexible tube or beam  1160  is provided in the collapsed configuration, whereas in  FIG.  17 B , the retractor system has a rigid beam that is formed from the flexible beam  1160 . More specifically, in this embodiment, the flexible beam  1160  is in the form of a rod or tube  1165  having a lumen to slidably receive therein a stabilizing or rigidifying structure such as a rigid tube or rod (beam)  1162 . The rigidifying (stabilizing) structure  1162  is independently actuated by the user by movement of actuator  1134 . Actuator  1134  is slidably mounted within a longitudinally extending slot of housing  1130 . In the initial position of  FIG.  17 A , rigidifying structure  1162  is retracted within a lumen of the catheter and either not engaged, or only partially engaged, with flexible tube (or rod)  1160 . Rigidifying structure  1162  attached at its proximal end to sliding block  1164  which is operably connected to actuator  1134 . To rigidify tube  1160 , actuator  1134  is slid distally to the position of  FIG.  17 B , thereby advancing sliding block  1164  and the attached stabilizing structure  1162  distally. Such movement advances the rigidifying structure  1162  through the lumen  1165  of the flexible tube  1160  to the distal end  1160   a  to thereby stiffen the beam. The rigidifying structure  1162  can optionally be removed from the flexible beam  1060  to return the system back to the original more flexible state to aid collapsing of the retractor system  1050  by sliding the actuator  1134  in the reverse direction (proximally) within the axial slot, thereby withdrawing rigidifying structure  1162  from the advanced position within flexible tube  1160 . In one embodiment, the rigidifying structure  1162  is in the form of a structure having a proximal and distal metal tubular structure joined by a flexible braid polyimide tube. However, it should be appreciated that other structures are also contemplated. Note the structures  1160 ,  1162  can be substantially circular in cross-section, although other cross-sectional shapes are also contemplated. As in the aforedescribed embodiments, the rigid beam limits deflection of the distal end  1111  of the catheter  1110  which could otherwise occur by pressure exerted on the distal end by the body lumen wall. 
     As shown in  FIGS.  17 A and  17 B , the actuator can include a connector  1135  having a tooth or pawl  1137  to engage a tooth on the rack  1138  positioned within housing  1130  to retain the rigidifying structure  1164  in one of several selected positions. 
     In the alternate embodiment of  FIGS.  17 C and  17 D , instead of advancing a rigidifying structure within the lumen of the flexible element, the rigidifying structure is advanced over the flexible element. More specifically, flexible beam  1160 ′ is rigidified by movement of a rigidifying structure, e.g., tubular member  1162 ′, over the flexible beam  1160 ′. That is, rigidifying member  1162 ′ has a lumen configured and dimensioned to receive flexible beam  1160 ′ as it is passed thereover in the direction of the arrow of  FIG.  17 C . Note that flexible element  1152  has been removed from  FIGS.  17 C and  17 D  for clarity. Actuator  1134 , as well as alternative methods, can be utilized for such movement. 
     A covering or cover  1170  is preferably provided at a distal end of the catheter  1110 . Covering  1170  in the illustrated embodiment is mounted around the perimeter of the proximal coupler  1140  and the distal coupler  1148 . In some embodiments, the cover  1170  is pleated and sealed around the couplers (caps)  1140 ,  1148  by a heat shrink wrap. The cover  1170  is positioned around the elements  1152 ,  1154 ,  1156 ,  1158  in the collapsed insertion position, with an opening in the cover  1170  facing toward the target tissue, e.g., the lesion to be removed. That is, in the orientation of  FIG.  15   , the opening in cover  1170  faces upwardly. The cover  1170  can be configured to have an opening in the collapsed position, or, alternatively, it can provided with a slit which can be opened due to stretching when the retractor elements  1152 ,  1154  are moved to the expanded position. When the retractor elements  1152 ,  1154  are expanded, they move past the cover  1170  toward the target tissue. Alternatively, the edges of the cover  1170  can be attached to the retractor elements  1152 ,  1154  and thereby move with the retractor elements. When the target tissue is removed by the endoscopic instruments described herein, the removed tissue is placed within the cover  1170 , and the cover  1170  is closed, e.g., by a string or suture  1172  shown in  FIG.  29    to encapsulate the tissue and prevent leakage and seeding during removal from the body lumen. The suture  1172  can be embedded in a wall of the cover  1170  or in pockets or channels formed in the cover  1170 , where it is permanently fixed at a distal anchor point, and pulled proximally to tension the suture  1172  and close the cover  1170 . 
     As with the cover (sheath)  1000  of  FIG.  10   , the cover  1170  by covering the retractor elements  1152 ,  1154 ,  1156 ,  1158  can provide a smooth and atraumatic surface for the delivery of the retractor system to the target site. The cover  1170 , like cover  1000 , also helps to prevent tissue, e.g. the luminal walls, from entering through the spaces between the beam  1160  and elements  1156 ,  1158  during the surgical procedure. 
     In a preferred embodiment, the two ends of suture  1172  extend out of tubing  1139 . Their proximal ends can be covered by a length of tubing to facilitate grasping by the user. The suture  1172  extends through switch  1137  and tubing  1139 , through a dedicated lumen (channel) in the catheter, through the covering  1170 , and is looped at the distal cap  1148  where it is attached (anchored). During the procedure, the suture  1172  remains untensioned. After the tissue is placed within the cover (bag)  1170 , the two proximal ends of the looped suture  1172  are pulled proximally to tension the suture  1172  to close the cover  1170 . The switch can then be moved to frictionally engage to the suture  1172  to secure it so it locks in the tensioned position to maintain closure of the cover  1170 . 
     The use of the system of  FIG.  11    will now be described with reference to removing a lesion, such as a polyp, from a colon wall, it being understood, however, that the system  1100  can used for other procedures within the colon or the gastrointestinal tract, as well as used for other procedures in other body lumens or body spaces of a patient. 
     Turning first to  FIGS.  12  and  13   , a distal viewing endoscope  1200 , in which the system  1100  has been advanced over the proximal end  1201  as shown in  FIG.  12   , or alternatively the system  1100  backloaded over the distal end of the endoscope  1200 , is inserted through lumen A in the colon B in a procedure to remove the target polyp C from the wall of the colon B. The endoscope  1200  in this embodiment is a distal viewing scope with a wide distal viewing area of about 150-170 degree range so the polyp C and surrounding area can be visualized. After placement of the scope  1200  adjacent the target issue, i.e., slightly proximal of the target polyp C, the system  1100  is further advanced over the endoscope  1200 . Distal coupler (cap)  1148  has an opening  1148   a , and proximal coupler (cap)  1140  has an opening communicating with the lumen  1116  ( FIG.  16   ) of the catheter  1110  to enable such backloading of the endoscope  1200  and advancement of the system  1100  thereover. The catheter  1110  is advanced over the endoscope  1200  as shown in  FIG.  14    until it reaches the target site as shown in  FIG.  15   , with the retractor system  1050  aligned with the polyp C. As can be appreciated, in this insertion position of the catheter  1110 , the retractor system  1150  is in the non-expanded (or collapsed) position, with retractor elements  1152 ,  1154 , preferably not exceeding, or only slightly exceeding, the transverse dimension of the catheter  1110 . In this position, the retractor elements, or at least retractor elements  1156 ,  1158 , are covered by the covering  1170 . As shown, in this position, the distal end  1202  of the endoscope  1200  is preferably positioned at the end of proximal coupler  1140  and does not extend into the working space  1151  to thereby leave more room for maneuvering of the endoscopic instruments within the working space. Other positions, however, are also contemplated, e.g., in some versions the endoscope can extend into the working space  1151 . Note also in this insertion position, actuators  1134  and  1132  are in their retracted position as shown in  FIG.  16   . 
     Next, to rigidify the retractor system  1150 , the actuator  1134  is moved distally from the position of  FIG.  17 A  to the position of  FIG.  17 B  (see also the arrow in  FIG.  16   ) to advance rigidifying structure  1162  from the retracted position to an advanced position within lumen  1165  of flexible tube  1160 . This stiffens/stabilizes the retractor system  1150  as discussed above. Note, as discussed above, the retractor system  1150  can alternatively be stiffened/stabilized by advancement of a rigidifying structure over the flexible element as shown in  FIGS.  17 C and  17 D . 
     The retractor system  1150  is now expanded. Actuator  1132  is advanced distally from the position of  FIG.  20 A  to the position of  FIG.  20 B  (see also  FIG.  19   ). This advances block  1146  (which is operably coupled to retractor elements  1152  and  1154  as discussed above) which forces retractor elements  1152 ,  1154  laterally outwardly to the position of  FIG.  20 B , thereby creating the asymmetric working space (chamber) as described in detail above. 
     Next, tool channels  1122 ,  1124  are inserted through the ports  1115 ,  1117  in the proximal region of the catheter  1110  (see  FIG.  19 A ) and advanced by the user through the catheter lumens  1112 ,  1114  so they extend out the distal openings of the lumens  1112 ,  1114  and into the chamber  1151  as shown in  FIG.  21 A . Note as they emerge from the lumens  1112 ,  114 , and out of the confines of the lumen walls of the catheter  1110 , their distal tips  1122   a ,  1124   a  return to their curved (bent) position, curving upwardly (as viewed in the orientation of  FIG.  21 A ) toward the polyp C. Note in  FIG.  21 A , the retractor elements are first expanded, followed by insertion of the tool channels  1122 ,  1124  out of the catheter lumens  1112 ,  1114  and into the working space  1151 . However, it is also contemplated that in an alternative embodiment, the tool channels  1122 ,  1124  can be inserted through the catheter lumens  1112 ,  1114  and into the working space  1151  prior to expansion of the retractor elements  1152 ,  1154 . This alternate method is shown in  FIG.  21 B , with the tool channel tips  1122   a ,  1122   b  exposed, but the retractor system  1150  still in the non-expanded position. Note the tool channels  1122 ,  1124  can be independently rotated and/or moved axially to adjust their position with respect to the polyp C. As can be appreciated, the terms upwardly and downwardly as used herein refer to the orientation of the system in the referenced Figures. If the position of the system changes, the orientation and terms would also change. 
     After insertion of the tool channels  1122 ,  1124 , endoscopic instrument (tool)  1210  is inserted through the luer fitting  1129  ( FIG.  19 A ) of the tool channel  1124  and advanced through the lumen (channel) of the tool channel. As shown in  FIG.  22   , a first endoscopic instrument  1210  extends from tool channel  1124  and follows the curve of the tool channel  1124 . A second endoscopic instrument (tool)  1220  is inserted through the luer fitting  1127  of tool channel  1122  and advanced through the lumen of the tool channel  1122 . As shown in  FIG.  23   , the second endoscopic instrument follows the curve of the tool channel  1122 . As noted above, the tool channels can include a valve, such as the hemostatic valves as shown in  FIG.  19 B , so insufflation is not lost during insertion and removal of the endoscopic instruments from the tool channels. The endoscopic instruments  1210 ,  1220  can be moved further axially as shown in  FIGS.  24  and  25    to extend further from the tool channels  1122 ,  1124  to contact and treat, e.g., remove, the polyp C. This movement of the endoscopic instruments shown by comparing  FIGS.  23 - 25    shows the advantage of the tool channels  1122 ,  1124 . As can be seen, once the tool channels  1122 ,  1124  are in the desired position with respect to the polyp C, they can be considered as defining a fixed curve. This means that when the endoscopic instruments  1210 ,  1220  are axially advanced, they move closer to the target polyp C, without a change in curvature and without a change in their axial position with respect to the polyp C, thus providing an extra degree of freedom. The endoscopic instrument  1210 , which in the illustrated embodiment is a grasper, applies tension on the polyp C while the electrosurgical dissector  1180  dissects/severs the polyp C from the colon wall B. Other endoscopic instruments for polyp removal can also be utilized. Additionally, in some embodiments, a single tool channel can be utilized and another endoscopic instrument, e.g., a grasper or a dissector, can be inserted through a working channel (lumen) of the endoscope. Such instrumentation inserted through an endoscope can also be utilized with the embodiments having two or more tool channels. 
     Also note that due to the angles of the tool channels  1122 ,  1124  and thus the endoscopic instruments inserted therethrough, tissue triangulation can be achieved as depicted by the dotted lines in  FIG.  30   . 
     After removal of the polyp C from the colon wall B, it is placed within the cover  1170  as shown in  FIG.  26   , ready for removal from the body. Actuator  1134  can be moved proximally to return the retractor system to the more flexible condition if desired. Actuator  1132  is moved proximally in the direction of the arrow of  FIG.  27    to return the expanded retractor elements  1152 ,  1154  to their collapsed position of  FIG.  28    for removal of the catheter  1110 . The string or suture  1172  is then tensioned to close the cover (bag)  1170  as shown in  FIG.  29   , forming a bag to encapsulate the polyp C. The switch  1175  can then be moved to the position of  FIG.  31 B  to lock the string  1172  and thereby maintain the cover  1170  in the closed position. Catheter  1110  is then removed from the colon B with the polyp C protected (encapsulated) within the cover  1170 . Note that the cover  1170  is preferably transparent so that the drawings illustrate the retractor elements, bridge members, beam, etc. However, to facilitate understanding of the cover  1170 ,  FIG.  29    shows the retractor elements, bridge elements, beam etc. in phantom insider the bag/cover  1170 . 
       FIGS.  32 - 42    illustrate alternative embodiments of the system of the present invention. The system includes floating (flexible) channels within the outer tube. In one embodiment, the floating channels are fixed at their proximal and distal ends; in another embodiment the floating channels are fixed at their proximal ends but are unattached at their distal ends. As can be appreciated from the discussion below, the floating channels reduce the overall stiffness of the catheter (outer tube) which would otherwise be stiffer if the channels were fixed along their entire length and did not float within the catheter. The floating channels also reduce kinking of the tool channels (flexible guides) inserted through the floating channels and reduce kinking of the tools inserted through the tool channels (or inserted directly through the floating channels in the embodiments where the tool channels are not utilized). 
     More specifically, in the embodiment shown in  FIGS.  32 - 34   , the system  1210  includes a flexible catheter or outer tubular member (main tube)  1212 . The proximal portion of the outer tube  1212  is designated generally by reference numeral  1214  and the distal portion is designated generally by reference numeral  1216 . A proximal end cap  1218  is positioned over distal portion  1216  of outer tubular member  1212 . 
     A handle housing  1251  similar to handle housing  1130  of  FIG.  11    described above is composed of two half shells  1251   a ,  1251   b  attached together. Shell  1251   b  has an actuator  1252  in the form of a sliding button, although other forms of actuators can be provided. Actuator  1252  is connected to cage wire push tubes, such as push tubes  1428 ,  1430  of  FIGS.  40  and  42    described below, extending through outer tube  1212 . Distal movement of the actuator  1252  along slot  1254  causes distal movement of the push tubes  1428 ,  1430  which causes the flexible elements of the cage to bow outwardly as described below. At the distal end of the handle housing  1251  are access ports  1258   a ,  1258   b  for inflow tubes (not shown) which can be part of a member (organizer) secured within the handle housing  1251  at a proximal region. At the proximal end of the handle housing  1251  is a handle end cap  1253  with an opening  1262  for entry of an endoscope into the outer tube  1212 . Ports  1248 ,  1250  extend from proximal end cap  1253  to provide entry for the tool channels (flexible guides)  1270 ,  1271 . The ports  1248 ,  1250  preferably include a valve to maintain insufflation when the tool channels  1270 ,  1271  are inserted therethrough and translated axially therein. Markings  1264  can be provided on the handle housing  1251  to indicate to the user the extent of distal travel of the actuator  1252  to control the size of the expanded cage. For example, the markings provided can be “4, 5 and 6” to indicate expansion of the cage to 4, 5 or 6 centimeters, providing the user with a general indication of the incremental expanded positions. Other markings and/or extent of expansions are also contemplated. The actuator  1252  can have a plurality of teeth or other retention structure to retain the actuator  1252  and thus the retractor elements in select extended positions. 
     Actuator  1256  on shell  1251   a  provides for rigidifying the cage by rigidifying a flexible beam. As described below, in alternate embodiments, a separate slidable beam for rigidifying the cage is not provided as alternative rigidifying structure is provided. As in the embodiment of  FIGS.  17 A and  17 B , in this embodiment of  FIG.  33   , a stiffener member in the form of a rigid beam is operatively connected to actuator  1256  so that distal movement of the actuator  1256  advances the stiffener distally either within a lumen of the flexible element or over the outer surface of the flexible element to provide a stiffer structure. Actuator  1256  can be moved proximally to unstiffen the flexible element to facilitate collapse of the retractor system. 
     With reference to the cross-sectional view of  FIG.  37 A , the outer tube (catheter)  1212  in this embodiment has a single lumen  1213 . This lumen  1213  is dimensioned to receive 1) an endoscope  1200 , such as the endoscopes described above; and 2) two flexible channels  1222 ,  1224 . The two flexible channels  1222 ,  1224  are in the form of flexible tubes and float inside the lumen  1213 . That is, the two floating channels  1222 ,  1224  have intermediate portions that can move radially (laterally) within the lumen  1213  of the outer tube  1212 . Stated another way, the floating channels  1222 ,  1224  are unconstrained within the outer tube  1212  so they can bend relative to the outer tube  1212  so their bending action does not need to follow that of the outer tube  1212 . In this manner, when the outer tube  1212  is inserted in the body lumen and needs to bend to accommodate the curvatures of the body lumen, e.g., the gastrointestinal tract, the flexibility of the outer tube  1212  is maintained since the floating channels  1222 ,  1224  can move within the lumen  1213 . As can be appreciated, if the two channels were fixed with respect to the outer tube  1212  so there was no bending or movement with respect to the outer tube  1212 , and the channels were forced to bend in conformity with the outer tube  1212 , the outer tube  1212  would be much stiffer as the channels would have to carry the bending stresses which could limit bending of the catheter and/or cause kinking of the tool channels or tools extending through the channels of the catheter. Thus, in the embodiments of the present invention which include the floating channels, these advantages of increased flexibility are achieved. It should be understood that any of the systems disclosed herein could be provided with floating channels. Likewise, any of the systems disclosed herein could be provided without floating channels.  FIG.  37 B  provides by way of example a location of the floating channels  1222 ,  1224  when they are moved within the catheter  1212  as it is bent. Clearly, floating channels  1222 ,  1224  will move to various other positions in response to catheter bending. 
     Also, by providing a single lumen in this embodiment to receive the endoscope and the tool channels, rather than separate lumens which would require additional wall structure, a smaller diameter catheter can be provided which also reduces the overall stiffness of the catheter. 
     The endoscope  1200  in the embodiment of  FIG.  37 A  also floats within the lumen  1213 . That is, the endoscope occupies only a certain region of the lumen  1213  and can move radially (laterally) within the lumen  1213  of outer tube  1212  to increase the flexibility of the system. Thus, the endoscope  1200  can move relative to the outer tube  1212  in a similar manner as the floating channels  1222 ,  1224  can move relative to the outer tube  1212 . 
     In one embodiment by way of example, the internal diameter of the lumen  1213  of the outer tube  1212  ranges between about 5 mm and about 50 mm and is preferably about 10 mm to about 20 mm. Each of the floating channels preferably has an outer diameter of about 2 mm to about 10 mm, and preferably about 5 mm. The endoscope typically has a diameter of about 2 mm to about 20 mm and is preferably about 5 mm to about 12 mm. Thus, as can be appreciated, the floating channels and endoscope occupy only a small percentage of the internal lumen  1213 , leaving sufficient room for movement. Note that other dimensions and thus ratios of the floating channels and endoscope to the internal diameter of the lumen  1213  are also contemplated for the systems disclosed herein. 
     In one embodiment, by way of example, the outer tube  1212  has a length, measured from the distal end of handle  1251  to a distal edge of end cap  1218  of about 10 cm to about 200 cm, and more preferably about 60 cm to about 90 cm. The floating channels  1222 ,  1224  have a length of about 10.1 cm to about 204 cm, and preferably about 60.5 cm to about 91 cm, thereby exceeding the length of the outer tube  1212 . Other dimensions are also contemplated. This greater length of the floating channels  1222 ,  1224  in the embodiments where they are fixed at both the proximal and distal ends enables the floating movement. 
     Turning now to details of the floating channels and their securement within outer tube  1212 , in the embodiment of  FIGS.  32 - 34   , channel  1222 , referred to herein as a first flexible channel or a first floating channel or a first flexible tube, has a proximal end  1238  and an opposing distal end  1239 . Channel  1224 , referred to herein as a second flexible channel or a second floating channel or a second flexible tube, has a proximal end  1246  and an opposing distal end  1249 . Note the terms “first” and “second” to describe various components of the systems of the present invention are used herein for ease of description. Note in the embodiments of  FIGS.  32 - 42   , two floating channels are provided. It is also contemplated that only one floating channel is provided or more than two floating channels are provided. 
     Positioned with the outer tube  1212  at a distal end is a first fixed distal tube  1226  which forms a pocket for the first floating channel  1222 . First distal tube  1226  has an opening  1227 , a proximal edge  1236  and a distal edge  1237 . In some embodiments, instead of an opening  1227  the distal end can be closed. Preferably, distal edge  1237  is substantially flush with the distal edge of distal end cap  1218 . At the proximal end of the system, positioned either within the outer tube  1212  or alternatively at a distal region of the handle housing  1251 , is a first fixed proximal tube  1228 . 
     Also positioned with the outer tube  1212  at a distal end is a second fixed distal tube  1230  which forms a pocket for the second floating channel  1224 . Distal tube  1230  has an opening  1231 , a proximal edge  1242  and a distal edge  1243 . In some embodiments, instead of an opening  1231  the distal end can be closed. Preferably, distal edge  1243  is substantially flush with the distal edge of distal end cap  1218 . At the proximal end of the system, positioned either within the outer tube  1212  or alternatively at a distal region of the handle housing  1251 , is a second fixed proximal tube  1232  having a proximal edge  1246 . The first and second proximal tubes  1228 ,  1232  are preferably attached to an inner wall of the outer tube  1212  or handle housing  1251  by bonding or welding or other attachment methods. Similarly, the first and second distal tubes  1226 ,  1230  are preferably attached to an inner wall of the outer tube  1212  by bonding or welding or other attachment methods. Note in  FIG.  33   , the fixed proximal tubes  1228  or  1232  are shown cutaway (into a half cylinder) for clarity, it being understood that the tubes can be cylindrical in configuration like the distal fixed tubes  1226 ,  1230 . Other configurations for the fixed distal and proximal tubes are contemplated. 
     The distal end of the first flexible channel (tube)  1222  is positioned within the first fixed distal tube  1226  and secured thereto such as by bonding or welding or other attachment methods. It can terminate in any fixed position within the distal tube  1226 , and in the illustrated embodiment, terminates at the distal end of the distal tube  1226 . The proximal end  1238  of first flexible channel  1222  is positioned within the first fixed proximal tube  1228  and secured thereto such as by bonding or welding or other attachment methods. It can terminate in any fixed position within the proximal tube  1228 , and in the illustrated embodiment, terminates at the proximal end of the proximal tube  1228 . In this manner, the first flexible channel  1222  is fixed with respect to the outer tube  1212  at its proximal end and at its distal end. However, it remains unattached in an intermediate portion between the proximal and distal end, e.g., along its length between its two fixed ends, so it can float within the outer tube  1212 . Similarly, the distal end of the second flexible channel (tube)  1224  is positioned within the second fixed distal tube  1230  and secured thereto such as by bonding or welding or other attachment methods. It can terminate in any fixed position within the distal tube  1230 , and in the illustrated embodiment, terminates at the distal end of the distal tube  1230 . The proximal end of second flexible channel  1224  is positioned within the second fixed proximal tube  1232  and secured thereto such as by bonding or welding or other attachment methods. It can terminate in any fixed position within the proximal tube  1232 , and in the illustrated embodiment, terminates at the proximal end of the proximal tube  1232 . In this manner, the second flexible channel  1224  is fixed with respect to the outer tube  1212  at its proximal end and at its distal end. However it remains unattached in an intermediate portion between the proximal and distal end, e.g., along its length between its two fixed ends, so it can float within the outer tube  1212 . 
     First and second flexible guides or tool channels  1271 ,  1270  ( FIG.  33   ) are inserted through ports  1248  and  1250  in the same manner as flexible guides (tool channels)  1122 ,  1124  of  FIG.  19 A . The flexible guides  1271 ,  1270  extend through floating channels  1222 ,  1224 , respectively, to emerge out the distal ends into the chamber. Note flexible guides  1271  and  1270  can in some embodiments be composed of a Pebax tubing, an overlying PVC tubing and polyolefin shrink tubing over the PVC tubing. The other flexible guides disclosed herein can also be composed of such structure. This provides a balance between flexibility and rigidity, and also beefs up the proximal end to facilitate handling by the user. Note the flexible guides  1271 ,  1270  emerge from the proximal cap  1218  and bend at their distal tips in the same manner as flexible guides (tool channels)  1122 ,  1124 . Therefore, since the flexible guides  1271 ,  1270  are identical in function for guiding/bending working instruments inserted therethrough, for brevity they will not be discussed further since the discussion of flexible guides  1122 ,  1124  above is fully applicable to flexible guides  1271 ,  1270 . Note for clarity the flexible guides are not shown in the other Figures, it being understood that they would function in the manner of  FIGS.  21 - 25   . 
     In an alternate embodiment of  FIGS.  35 A- 35 C , the floating (flexible) channels are fixed at their proximal end but remain free (unattached) at their distal ends. More specifically,  FIGS.  35 A- 35 C  illustrate a cutaway view of the system so that only one of the floating channels, the second floating channel  1324 , is illustrated. The first floating channel is attached and configured in a similar fashion as second floating channel  1324 . Second floating channel  1324  is attached at its proximal end in the same manner as floating channel  1224 , i.e., attached within a fixed proximal tube. The first floating channel  1322  is not shown in  FIGS.  35 A- 35 C  but is shown in  FIG.  38    and is attached at its proximal end in the same manner as first floating channel  1222 , i.e., attached within a fixed proximal tube. The floating channels  1322 ,  1324  differ from the floating channels  1222 ,  1224  of  FIG.  32    in that they are unattached at their distal ends. Consequently, the floating channels  1322 ,  1324  form telescoping channels within the outer tube (or catheter)  1312 . 
     More specifically, with continued reference to  FIGS.  35 A- 35 C  and  FIG.  38   , a first fixed distal tube  1326  is attached within the outer tube  1312  adjacent proximal end cap  1318  positioned over the outer tube (catheter)  1312  of the system  1310 . First fixed distal tube  1326  forms a pocket for the first floating channel  1322 . Distal tube  1326  has a lumen extending therethrough, a proximal edge  1325  and a distal edge  1329 . Preferably, distal edge  1329  is substantially flush with the distal edge of proximal end cap  1318 . A second fixed distal tube  1330  is attached within outer tube  1312  adjacent the proximal end cap  1318  and forms a pocket for the second floating channel  1324 . Distal tube  1330  has a lumen  1331  extending therethrough, a proximal edge  1333  and a distal edge  1338 . Preferably distal edge  1338  is substantially flush with the distal edge of proximal end cap  1318 . Second floating channel  1324  has a distal end  1337  which in the position of  FIG.  35 A  is fully within the second fixed distal tube  1330 . Upon bending of the outer tube  1312  in one direction, the second floating channel  1324  moves distally to the position of  FIG.  35 B . Upon additional bending, the floating channel  1324  can extend beyond the distal edge  1338  of the second fixed distal tube  1330  (and beyond the distal edge of the proximal end cap  1318 ) as shown in  FIG.  35 C .  FIG.  38    (and  FIG.  39 B ) illustrates the effect in bending of the outer tube  1312  in the opposite direction of  FIG.  35 C . As shown, the second floating channel  1324  remains within the lumen  1331  of the second fixed distal tube  1330  while the distal end  1327  of first floating channel  1322  extends distally beyond the distal edge  1329  of first fixed distal tube  1326  (and beyond the distal edge of the proximal end cap  1318 ). 
     Stated another way, the floating channels  1322 ,  1324  are unconstrained within outer tube (catheter)  1312  and take the shortest path when the outer tube  1312  is bent. Thus, the movement readjusts their position to adjust for the length difference on bending of the outer tube  1312 . Note the floating channels  1322 ,  1324  can also slightly rotate during bending of the outer  1312  to compensate for stress applied to the floating channels during bending. Consequently, this prevents the eccentric positioned channels from being stretched on the outer portion of the curvature and buckling on the inner portion of the curvature. The floating channels can move around within lumen  1315  of outer tube  1312  and take any shape to accommodate bending to increase the flexibility of the device. 
     Note that in  FIG.  35 C  the outer tube  1312  is bent in a first direction so that second floating channel  1324  on the inside curvature of the outer tube  1312  is advanced distally beyond distal tube  1330 . In  FIG.  38   , the outer tube  1312  is bent in a second opposite direction so that the first floating channel  1322  on the inside curvature of the outer tube  1312  extends beyond the distal tube  1326 . 
     The fixed distal tubes  1326 ,  1330  which form pockets for the respective floating channels  1322 ,  1324  are dimensioned so their length exceeds the largest extent of movement in response to the greatest curvature of the outer tube  1312  as a result of bending of the outer tube  1312  during use. This ensures that the floating channels  1322 ,  1324  will not retract out of the proximal end of the respective fixed distal tubes  1326 ,  1330 , In a preferred embodiment, the length of the distal tubes  1326  and  1330  are between about 1.5 cm to about 3 cm, and preferably about 2 cm. Other dimensions are also contemplated. 
     Flexible guides identical to flexible guides  1270 ,  1271  of  FIG.  33    and/or flexible guides  1122 ,  1124  of  FIGS.  19 - 25    are inserted through the floating channels  1322  and  1324  in the same manner as described above so that endoscopic working instruments can be inserted into the chamber formed by the flexible elements for performing the procedure. Note, alternatively, endoscopic working instruments can be inserted directly through the floating channels of any of the embodiments herein without the intermediary flexible guides. Such direct insertion of instrumentation without flexible guides (tool channels) is also described above as an alternative system and method. 
     The working instruments can include graspers for example. A dissecting/cutting instrument can be inserted through the flexible guide in the floating channel, or alternatively inserted through a working channel of the endoscope. Thus, various working instruments can be inserted through the flexible channels and endoscope channel(s). 
     The flexible guides described herein, e.g., flexible guides  1270 ,  1271 , can be color coded to improve the system&#39;s usability. For example, flexible guide  1270  can be of a first color, such as red, and flexible guide  1271  can be of a second color, such as black. In this way, when the user is manipulating the flexible guides  1270 ,  1271  at their proximal ends outside the patient&#39;s body, the user will more readily see the corresponding color coordinated tip being manipulated within the expanded cage. Note the entire flexible guide can have the same color or alternatively the matching color can be only at the proximal end visible to the user and the distal end visible by the endoscope. It should also be appreciated, that instead of color coding, other indicia can be provided so the user can match the proximal end of the flexible tube with the distal end within the chamber. 
       FIGS.  39 A- 39 C  illustrate the distal portion of the system  1310  to show the retractor elements in the expanded configuration to form the asymmetric cage to create a working space for the surgical procedure. The retractor system  1370  is identical to the retractor system  1150  of the embodiment of  FIG.  21 A  and therefore when expanded from its collapsed insertion position forms a working space expanding system and in certain surgical procedures a body lumen reshaping system which reshapes the body lumen to form an asymmetric space to increase the working space for the maneuverability of the endoscopic instruments through the flexible guides of the system. That is, the retractor system creates a self-contained “surgical suite” which forms an expanded area within the body lumen for the surgeon to perform the surgical procedure within the created space. By reshaping the body lumen, the working space is maximized without overstretching the body lumen. Such working space maximization increases the distance between the target tissue and the end effectors of the endoscopic instruments, hence improving maneuverability of the instruments during the surgical procedure. Note the flexible tool channels (flexible guides) and endoscopic instruments are not shown in these drawings for clarity but would operate in the same manner as in  FIGS.  21 - 25   . The retractor system of system  1210  of  FIGS.  32  and  33    is identical to the retractor system  1370  of system  1310  and therefore the discussion of the structure and function of the retractor system  1370  is fully applicable to the retractor system of system  1210 .  FIG.  36    discussed below illustrates an example of the reshaping of the body lumen to a more oval-like configuration. 
     As noted above, retractor system  1370  is identical to retractor system  1150  and includes flexible retractor elements  1380 ,  1382  which create the working chamber (space) within the body lumen and form an asymmetric cage. Flexible retractor elements  1384 ,  1386  form the base of the retractor system  1370 . Movement of the retractor elements  1380 ,  1382 ,  1384  and  1386  is the same as retractor elements  1152 ,  1154 ,  1156  and  1158  described above and/or the same as movement of the retractor elements of  FIGS.  40 - 42    described below. The retractor system  1370 , also like retractor system  1150 , can include a bridge member  1390  spanning retractor elements  1380 , 1382  and optionally a bridge member  1392  spanning retractor elements  1384 ,  1386 , which are configured and function in the same manner as aforedescribed bridge members  1155 ,  1157  and therefore for brevity are not described herein again in detail as the description above for bridge members  1155 ,  1157  and their alternatives are fully applicable to the retractor system  1370 . 
     The retractor elements  1380 ,  1382 ,  1384 ,  1386  can be made of substantially flexible materials and are preferably formed of a wire composed of nitinol. A layer of soft compatible material, but preferably PTFE tubing  1387 , can be positioned over a portion of the wires. A polyolefin heat shrink  1389  can be positioned over the retractor portion of the elements and bridge member to retain the bridge members. Note the retractor elements angulate at the distal end, i.e., pivot from the distal cap  1374 . To bulk up the retractor elements adjacent this region, a covering material such as the PTFE tubing can be provided. 
     Flexible tube or beam  1391  in the form of a rod or tube has a lumen to receive a stabilizing or rigidifying structure such as rigid tube or rod  1393 . (Alternatively, the rigid tube or rod can be slid over beam  1391 ). Flexible beam  1391  and rigidifying structure  1393  are identical to flexible beam  1160  and rigid beam  1162  of  FIGS.  17 A,  17 B  described above. Therefore, for brevity, further details of these components are not provided herein since the structure and function of the beams  1160 ,  1162  provided in detail above are fully applicable to the beams  1391 ,  1393 . An actuator like actuator  1256  of  FIG.  33    is operably connected to the rod  1393  for sliding movement with respect to beam  1391  to increase the rigidity of the cage. Alternative structure for the rigidifying structure described above, such as sliding a rigidifying structure over a flexible beam, are also fully applicable as alternatives to the rigidifying structure of the retractor system  1370  of  FIG.  39 A  and the retractor system of the system  1210  of  FIGS.  32  and  33   . 
     A covering or cover  1378  identical to cover  1170  of  FIGS.  28  and  29    of Figure is provided. The cover  1378  covers the retractor elements  1380 ,  1382 ,  1384 ,  1386  and in the expanded position of the retractor system  1370  has an opening  1395  for access to the tissue. Further details of the cover  1395  are not provided herein since the cover  1395  is identical in structure and function to cover  1170 . Also, the various embodiments of the covers described above are fully applicable to the cover for the systems of  FIGS.  32 - 42   . 
     In alternate embodiments, the pursestring to close the cover  1378  of  FIGS.  32 - 42    or the cover of any over the aforedescribed covers is eliminated and reliance is on the cover itself. Elimination of the pursestring simplifies the device by providing fewer components and reduces the steps in the surgical procedure. In embodiments without the pursestring, when the tissue, e.g., the severed polyp, is pulled into the cage formed by the retractor elements, and the retractor elements return to their non-expanded position to collapse the cage, the cover closes down on the captured tissue, e.g., the polyp, to prevent or minimize seeding of the pathological tissue, e.g., cancerous tissue, during removal. The grasper can also maintain its grip on the severed tissue so the grasped tissue and catheter are removed together from the body lumen. The target tissue, e.g., polyp, during the procedure and during its removal from the body would typically be located inside the cage and practically isolated by the cage and its cover from the surrounding innocent tissues. 
       FIGS.  40 - 42    illustrate an alternative retractor system of the present invention. The retractor system  1415  of system  1410  is identical to the retractor system  1370   FIG.  39 A  (and system  1150  of  FIG.  17 C ) except for the rigidifying structure. In this embodiment, instead of a movable beam to stiffen an otherwise flexible element, an element of the retractor system has inherent stiffness characteristics to stiffen the overall retractor system  1415 . More specifically, retractor system  1415  has flexible retractor elements  1412 ,  1414  which expand (bow outwardly) to form the chamber (cage) to create the working space in the same manner as retractor elements  1380 ,  1382  described above. These flexible elements  1412 ,  1414  are expanded by movement of actuator  1416  in the same manner that movement of actuator  1252  ( FIG.  33   ) expands flexible retractor elements  1380 ,  1382 . That is, actuator  1416  is attached to block or carriage  1426  which contains a slot or opening for attachment of push cable  1428 . Push cable  1430  is also attached within another slot or opening of block  1426 . Thus, push cables  1428 ,  1430  are operatively connected at their proximal ends to actuator  1416 . A connection tube  1432  connects push cable  1428  to flexible element  1414  and connection tube  1434  connects push cable  1430  to flexible element  1412 . The connection tubes  1432 ,  1434  are at the distal end of the outer tube  1411  at the region of the proximal cap  1413 . More specifically, a distal end of push cable  1428  is secured within connection tube  1432  and a proximal end of flexible retractor element  1414  is secured within connection tube  1432 . A distal end of push cable  1430  is secured within connection tube  1434  and a proximal end of flexible retractor element  1412  is secured within connection tube  1434 . Slidable advancement of actuator  1416  within slot  1436  of handle housing  1438  moves push cables  1428 ,  1430 , distally which bows flexible elements  1412 ,  1414  outwardly to an expanded position due to their attachment at distal end cap  1417 . Markings  1440  can be provided to indicate retractor element expansion as in  FIG.  33   . 
     Retractor system  1410  also has flexible elements  1418 ,  1420  forming the base of the cage and identical to retractor elements  1384 ,  1386  described above. Retractor system  1415 , however, differs from retractor system  1370  (and  1150 ) in that a beam  1422  is provided which itself has sufficient rigidity to maintain the overall stiffness of the expanded cage when fairly mild forces are applied (e.g., weight of small portion of the intestinal wall, minor external intra-abdominal pressure, etc.) and limit bending of the cage with respect to the outer tube  1422  during use when fairly mild forces are applied. That is, the beam  1422  extending from the proximal cap  1413  to the distal cap  1417  maintains the rigidity of the system when fairly mild forces are applied as it is fixed at both ends and extends the length of the expanded cage. The rigidity of the beam  1422 , however, is optimized to be sufficiently flexible when fairly significant force is applied to it (e.g., bending force of the endoscope). This rigidifying of the beam can be achieved in several ways. In some embodiments, the wire element which forms the rigidifying beam itself is sufficiently rigid to achieve the stability of the expanded cage. However, to further increase the rigidity, but preserve the desired flexibility, the rigidifying beam in alternate embodiments can have an increased thickness to further optimize the bending of the cage&#39;s elements such as beam  1422 . As shown, in this embodiment, the diameter or (cross-sectional dimension if a non-circular beam is used) is greater than the diameter (or cross-sectional dimension if non-circular elements are used) of the flexible elements  1412 ,  1414 ,  1418 , and/or  1420 . In other embodiments, the rigidifying beam can be composed of a stiffer material than one or more of the other flexible elements. Such stiffer materials can include for example steel or plastic. 
     Note the flexible tool guides (tool channels) are not shown in  FIGS.  40 - 42    for clarity, but flexible guides such as flexible guides  1270 ,  1271  of  FIG.  33    can be utilized. Also, in this embodiment only a single actuator is provided for expansion of the retractor system  1415  since an actuator for rigidifying the structure is not necessary. 
     In all other respects, system  1410  is identical to system  1310 . 
       FIGS.  43 A- 47 C  illustrate alternate embodiments for stabilizing the chamber. In these embodiments, a distally positioned expandable stabilizing structure is provided which stabilizes the distal portion of the catheter. As can be appreciated, one way to enhance stabilization is to fix the distal point of the chamber so that when the flexible elements forming the chamber are pushed forward, the flexible elements bulge to the side as the fixated distal point doesn&#39;t deviate to thereby provide support for the flexible elements. In the foregoing embodiments, this distal fixation is achieved by an elongated stabilizing rod which can be fixed relative to the catheter or can be selectively rigidified to form a more rigid beam by a rigidifying member slid thereover or therein as described in detail above. In the embodiments of  FIGS.  43 A- 47 C , the stabilization is achieved by an expanding stabilizing member at the distal end which selectively expands to fit the transverse dimension of the body space, e.g., the colon. In some embodiments, the expanding stabilizing member is axially fixed adjacent to or over a distal coupling structure for the flexible elements; in other embodiments the expanding stabilizing member is movable axially to a position adjacent or over the distal coupling structure. Additionally, in some embodiments, the expanding stabilizing member is an inflatable balloon; in other embodiments, the expanding stabilizing member is a mechanical structure such as a mesh or stent-like structure. Each of these variations is discussed in detail below. 
     As can be appreciated, in order to advance the catheter through the anatomy to the target site, sufficient flexibility is necessary. On the other hand, sufficient rigidity, i.e., distal fixation of the catheter, is required to bend the flexible elements and to maintain the chamber and thus the working space for treating the target tissue. The embodiments of  FIG.  43 A- 47 C  provide an approach to achieving this by providing fewer flexible elements than in the forgoing embodiments to thereby reduce the overall rigidity of the catheter while providing an expandable stabilizing structure at the distal end that can be collapsed and flexible for insertion and selectively expanded to rigidify and stabilize the system when the catheter is at the desired surgical site. 
     Note in the embodiments of  FIGS.  43 A- 47 C , the flexible elements are identical as are other components of the flexible catheter and system. Therefore, for ease of understanding, these like components in  FIGS.  43 A- 47 C , even though they disclose different stabilizing elements, are provided with the same reference numerals throughout the drawings. However, where these embodiments differ, e.g., the expandable stabilizing member, different reference numerals are utilized for ease of understanding the differences. 
     Turning first to the embodiment of  FIGS.  43 A- 43 D , system  1500  includes a multi-lumen catheter or tubular member  1510  configured to receive one or more tool channels or flexible instrument guides.  FIG.  43 C  shows two tool channels  1122  and  1124  (identical to the aforedescribed tool channels  1122 ,  1124 ), it being understood that in some embodiments, only one tool channel can be utilized and in other embodiments more than two tool channels can be utilized, with the catheter provided with a sufficient number of lumens. The tool channels  1122 ,  1124  can be packaged as a kit with the catheter  1510  in the same manner as shown in  FIG.  11   . Alternatively, the tool channels  1122 ,  1124  can be packaged separately. In other embodiments, the tool channels are packaged already inside the lumens of the catheter  1510 . Each tool channel  1122 ,  1124  has a lumen (channel) to receive an endoscopic instrument (tool) therethrough, such as the endoscopic instruments described above. The tool channels  1122 ,  1124  can be provided as floating channels within a lumen of the catheter as described in detail above. 
     The retractor system  1550 , which forms a working space expanding system, and in certain clinical applications, a body lumen reshaping or reconfiguring system, is positioned at the distal portion  1511  of catheter  1510  in the same manner as the retractor system  1150  is positioned at the distal portion  1111  of the catheter  1110  described above. The retractor system  1550  of catheter  1510  includes two flexible retractor elements  1552  and  1554 , although in alternate embodiments, additional flexible elements could be provided. Retractor elements  1552 ,  1554  form the expandable elements which create the working chamber (space) within the body lumen and form an asymmetric cage. Retractor elements  1552 ,  1554  are expandable to form an asymmetric working chamber to improve visibility and working space as described in detail above with respect to the other systems forming asymmetrical working spaces. Note retractor system  1510  differs from retractor system  1150  in that only two retractor elements extend from the proximal coupler  1540 . 
     As in retractor elements  1152  and  1154 , retractor elements  1552  and  1554  move from a collapsed insertion position wherein they preferably do not extend beyond, or significantly beyond, the transverse dimension of the catheter  1510  to an expanded position wherein they bow laterally outwardly beyond the transverse dimension of the catheter  1510 . As in the embodiments described above, the retractor system  1550 , i.e., the retractor elements  1552 ,  1554 , expand to only one side of a plane passing through a longitudinal axis of the catheter  1510 , thereby creating the asymmetric working space  1551  (and asymmetric cage), with its attendant advantages described herein. 
     Retractor elements  1552 ,  1554  can have a bridge member  1555  to add stability to the retractor i.e., the flexible retractor elements, during bending and maintain a desired orientation of the retractor elements during the expansion i.e., to facilitate controlled space expansion/reshaping. The bridge member  1555  is attached to the two retractor elements  1552 ,  1554 , preferably at an intermediate portion, to create a transverse structure for the elements  1552 ,  1554 , limiting side-to side movement. As shown, bridge member  1555  is identical to bridge member  1155  discussed above and therefore for brevity is not discussed in detail since the description and function of bridge member  1155  is fully applicable to bridge member  1555 . Note the bridge member  1555  can be a separate component attached to the retractor elements by tubular elements (like tubular elements  1159   a ,  1159   b  discussed above) which are fitted over and attached to the retractor elements  1552 ,  1554 , respectively. Other methods of attachment of the bridge members are also contemplated. Alternately, the bridge member  1555  can be integrally formed with one or both of the retractor elements  1552 ,  1554  respectively, to add to the stability of the retractor system. The bridge member  1555  can also include in certain embodiments legs  1555   a ,  1555   b  to provide additional stability similar to the legs  1155   d ,  1155   e  described above. 
     The catheter  1510  includes a proximal coupler (cap)  1540  through which the retractor elements extend in the same manner as proximal coupler  1140 . Retractor elements  1552 ,  1554  are fixedly attached at a distal end to coupling structure, i.e., distal coupler or distal nexus  1548  similar to distal coupler  1148 . The distal coupler  1548  has openings to receive retractor elements  1552 ,  1554  for securement to the coupler  1548  in the same manner as coupler  1148  described above. The retractor elements  1552 ,  1554  can be moved to the expanded (laterally outward/bowed) position in the same manner as retractor elements  1152 ,  1152 , e.g., by a slidable actuator. Note the proximal and distal couplers  1540 ,  1548  can have openings dimensioned to receive an endoscope when the catheter  1510  is backloaded over the endoscope as described herein. As described above, a plurality of teeth (not shown) similar to the teeth of  FIGS.  6 A- 6 D  can be provided in the housing for engagement by a tooth coupled to the actuator for the flexible elements, thereby forming a retaining or locking mechanism to retain the retractor elements in one of several select positions. A release mechanism for the retaining or locking mechanism can be provided. 
     Additionally, it should be appreciated that alternative ways to expand the retractor elements can be utilized, including for example providing relatively movable couplers  1540 ,  1548  to expand the retractor elements  1552 ,  1554  in the same manner described in the alternatives above. The retractor elements can also alternatively be made of self-expanding material, such as shape memory material, which expand when exposed from the catheter. 
     A sheath or covering material  1576  can be placed over the flexible elements  1552 ,  1554  for creating an enclosed space for capture and withdrawal of tissue. This is shown in  FIG.  43 D . (The covering is not shown in  FIGS.  43 A- 43 C  for clarity). The covering  1576  can be configured and function in the same manner as covering  1170  described above so that the aforedescribed description of the function and configuration of covering  1170 , and its alternatives, are fully applicable to covering  1576 . Note the covering material  1576  can be placed over the flexible elements in the other embodiments described herein. 
     An expandable structure (member)  1570  in the form of an inflatable balloon  1572  is positioned distal of the distal coupler  1548 . The balloon  1572  is positioned at a distal end of a catheter  1574  which has a lumen communicating with the interior of the balloon  1572  for inflation. The catheter  1574  extends through a lumen  1513  in catheter  1510  which can be a separate lumen or alternatively a region of the lumen that receives the endoscope and/or a tool channel. In the insertion position of the catheter  1510 , the balloon  1572  is in a collapsed non-inflated position to present a low profile. In the insertion position, the catheter  1574  is in an extended position, with the non-inflated balloon  1572  distal of the coupler  1548  (see  FIG.  43 B ). After insertion of the catheter  1510  to the desired position with respect to the target tissue, the catheter  1574  is retracted proximally within the lumen  1513  of catheter  1510  to retract the balloon  1572  axially toward the distal coupler  1548 . When positioned adjacent the distal coupler  1548 , just distal of the distal end of coupler  1548  and either slightly spaced or abutting, the balloon  1572  is inflated so the expanded balloon  1572  fills the transverse dimension within the body space, e.g. colon C, as shown in  FIG.  43 C . The retractor elements  1552 ,  1552  are moved to the expanded position, bowing outwardly, in the manner described above, e.g., by movement of an actuator operatively connected to the retractor elements  1552 ,  1554  to form the chamber for working instruments. 
     Note that the catheter  1574  and attached balloon  1572  (as in the other balloon or mechanical expander embodiments described below) can be retracted and positioned adjacent the distal coupler  1548  either before or after expansion of the retractor elements  1552 ,  1554 . Also note that the balloon  1572  can be inflated either before or after retraction to its proximal position adjacent the distal coupler  1548 . Such sequence of steps, i.e., axial movement and/or expansion of the expandable member before or after the expansion of the retractor elements can occur in the other embodiments herein. 
     Note as shown in  FIG.  43 C , the expanded retractor elements reshape the body lumen e.g., colon, and the balloon  1572  can be positioned distal of the reshaped lumen region, engaging the wall of the lumen to provide a fixed and therefore stabilized distal point for the retractor elements to stabilize the working chamber. 
     In the alternate embodiment of  FIGS.  44 A- 44 C , instead of the balloon retracted adjacent the distal coupler  1548 , the balloon  1582  is retracted to overlie the coupler  1548 . The expandable stabilizer structure  1581  of system  1580  includes a donut shape balloon  1582  having an opening  1586  larger than the transverse dimension (outer diameter) of the distal coupler  1548  so it can fit over the distal coupler  1548 . Balloon  1582  is attached to the distal end of catheter  1584  which is slidably received in the lumen of the catheter  1510  in the same manner as catheter  1574  described above. The balloon  1582  is positioned at a distal end of a catheter  1584  which has a lumen communicating with the interior of the balloon  1582  for inflation. The catheter  1584  has a bend  1588  to accommodate opening  1586 . Note the bend  1588  is shown by way of example, it being understood that other angulations, such as a softer curve, smaller angle, etc. can be utilized The system  1580  is the same as system  1510  except for the stabilizing feature, therefore for brevity the same features are not described. The inflatable balloon  1582  is initially positioned distal of the distal coupler  1548 . The catheter  1584 , like catheter  1574 , slidably extends through a lumen in catheter  1510  which can be a separate lumen or alternatively a region of the lumen that receives the endoscope and/or a tool channel. 
     In the insertion position of the catheter  1510 , the balloon  1582  is in a collapsed non-inflated position to present a low profile for insertion. In this insertion position, the catheter  1584  is in an extended position, with the non-inflated balloon  1582  distal of the coupler  1548 . After insertion of the catheter  1510  to the desired position with respect to the target tissue, the catheter  1584  is retracted proximally within the lumen of catheter  1510  to retract the balloon  1582  axially toward the distal coupler  1548  and over the coupler  1548 . When positioned over the distal coupler  1548  such that the distal coupler  1548  is seated within opening  1586  in balloon  1582 , the balloon  1582  is inflated (or further inflated if partially inflated prior to partial of full retraction) to fill the transverse dimension within the body space, e.g., colon, like the way balloon  1572  fills the space in  FIG.  43 C ). Note alternatively the balloon  1582  can be fully inflated prior to retraction over distal coupler  1548 . The retractor elements  1552 ,  1554  are moved to the expanded position, bowing outwardly, in the manner described above, e.g., by movement of an actuator operatively connected to the retractor elements  1552 ,  1554  to form the chamber for working instruments. As noted above, the retractor elements  1552 ,  1554  can be expanded before or after inflation of the balloon  1582  and before or after retraction of the balloon  1582 . 
     In the alternate embodiment of  FIGS.  45 A- 45 B , instead of the stabilizing structure, i.e., the balloon, retracted to a position adjacent to or overlying the distal coupler  1548 , balloon  1592  of stabilizer structure  1591  of system  1590  is axially fixed in a position overlying the distal coupler  1548 . The balloon  1592  is donut shaped like balloon  1582  having an internal opening dimensioned to fit over the distal coupler  1548 . Balloon  1592  is at the distal end of catheter  1594  which is axially fixed within the lumen of the catheter  1510 . The interior of the balloon  1592  communicates with the lumen in catheter  1594  for inflation of the balloon. The system of  FIGS.  45 A,  45 B  is otherwise the same as system  1580 , therefore for brevity the same features are not repeated herein. In use, the catheter  1510  is inserted with the balloon catheter  1594  fixedly positioned therein and the balloon  1592  in the non-expanded position lying over the distal coupler  1548  as shown in  FIG.  45 A . During the procedure, the balloon  1592  is inflated via the inflation lumen extending through catheter  1594  and in communication with the balloon interior to expand the balloon  1592  to the position of  FIG.  45 B  to stabilize the chamber formed by the expanded retractor elements  1552 ,  1554 . 
       FIGS.  46 A- 47 C  illustrate alternate embodiments of the stabilizing structure having a mechanical expander instead of an inflatable balloon. Turning first to  FIGS.  46 A- 46 C , in this alternate embodiment, instead of a balloon retracted adjacent the distal coupler  1548 , a mesh structure  1602  is utilized to stabilize the chamber. The expandable stabilizer structure  1601  of system  1600  includes a structure composed of a series of wires, fibers or other material formed into a mesh structure with sufficient rigidity to provide a stabilizing structure for the chamber. Mesh structure  1602  is positioned within a distal end of catheter  1604  which is slidably received in the lumen of the catheter  1510  in the same manner as catheter  1574  described above. An actuator  1606 , such as a push or pull rod is slidably received within the lumen of catheter  1604  and attached to the mesh structure  1602 , e.g., at a distal end, to expand and collapse the mesh structure. The system  1600  is the same as system  1510  except for the stabilizing feature, therefore for brevity the same features are not described. The mesh structure  1602  is initially positioned distal of the distal coupler  1548 . The catheter  1604 , like catheter  1574 , slidably extends through a lumen  1513  in catheter  1510  which can be a separate lumen or alternatively a region of the lumen that receives the endoscope and/or a tool channel. 
     In the insertion position of the catheter  1510 , the mesh  1602  is in a collapsed non-expanded position to present a low profile for insertion. In this insertion position, the catheter  1604  is in the extended or distal position of  FIG.  46 A , with the non-expanded (collapsed) mesh  1602  distal of the coupler  1548 , i.e., spaced further from the coupler  1548 . After insertion of the catheter  1510  to the desired position with respect to the target tissue, the catheter  1604  is retracted proximally within the lumen  1513  of catheter  1510  to retract the mesh structure  1602  axially toward the distal coupler  1548  to the position of  FIG.  46 B . In the illustrated embodiment, the mesh structure  1602  is retracted adjacent the distal coupler  1548 , either slightly spaced or in abutment. In alternate embodiments, the mesh structure  1602  has an opening like opening  1586  of balloon  1582  of  FIG.  44 B  dimensioned to fit over the distal coupler  1548  so the mesh structure  1602  can be retracted to overlie the distal coupler  1548 . Once retracted, the push/pull rod  1606  is pulled axially (or further pulled if partially pulled prior to retraction) to expand mesh  1602  to fill the transverse dimension within the body space, e.g., colon, like the way balloon  1572  fills the space in  FIG.  43 C . The retractor elements  1552 ,  1554  are moved to the expanded position, bowing outwardly, in the manner described above, e.g., by movement of an actuator operatively connected to the retractor elements  1552 ,  1554  to form the chamber for working instruments. As noted above, the retractor elements  1552 ,  1554  can be expanded before or after proximal movement of the mesh structure  1602  toward the distal coupler  1548  and before or after expansion of the mesh structure  1602 . 
     Note as an alternative to push/pull rod  1606 , the catheter  1604  can include a pusher and the mesh  1602  is retained in a collapsed position within the catheter  1604 . When the catheter  1604  is moved to the desired site, the pusher is advanced distally to force the mesh  1602  out of the distal end of the catheter  1604  to enable it to automatically expand to the expanded position of  FIG.  46 C  due to its spring like characteristics or its shape memory material. 
     In an alternate embodiment, catheter  1604  is axially fixed within catheter  1510  and the mesh structure  1602  is therefore axially fixed with respect to the distal coupler  1548 , positioned distally adjacent or overlying the coupler  1548 . Thus, in this embodiment, the mesh  1602  is in this fixed axial position when collapsed and inserted and remains in the fixed axial position when expanded. 
     An alternate expandable mechanical stabilizing structure is illustrated in  FIGS.  47 A- 47 C . In this embodiment, instead of a mesh structure, a stent-like structure  1612  is provided formed by a plurality of struts interconnected to form a plurality of geometric shapes. Stent structure  1612  is positioned within the distal end of catheter  1614  which is slidably received in the lumen of the catheter  1510  in the same manner as catheter  1574  described above. An actuator  1616 , such as a push or pull rod, is slidably received within the lumen of catheter  1614  and attached to the stent structure  1612 , e.g. at a distal end, to move the stent structure  1612  between the collapsed and expanded positions. The system  1610  is the same as system  1510  except for the stabilizing feature, therefore for brevity the same features are not described. The stent structure  1612  is initially positioned distal of the distal coupler  1548 . The catheter  1614 , like catheter  1574 , slidably extends through a lumen  1513  in catheter  1510  which can be a separate lumen or alternatively a region of the lumen that receives the endoscope and/or a tool channel. 
     In the insertion position of the catheter  1510 , the stent structure  1612  is in a collapsed non-expanded position to present a low profile for insertion. In this insertion position, the catheter  1614  is in the extended or distal position of  FIG.  47 A , with the non-expanded (collapsed) stent structure  1612  distal of the coupler  1548 , i.e., spaced further from the coupler  1548 . After insertion of the catheter  1510  to the desired position with respect to the target tissue, the catheter  1614  is retracted proximally within the lumen  1513  of catheter  1510  to retract the stent structure  1612  axially toward the distal coupler  1548  to the position of  FIG.  47 B . In the illustrated embodiment, the stent structure  1612  is retracted adjacent the distal coupler  1548 , either slightly spaced or in abutment. In alternate embodiments, the stent structure  1612  has an opening like opening  1586  of balloon  1583  dimensioned to fit over the distal coupler  1548  so the stent structure  1612  can be retracted to overlie the distal coupler  1548 . Once retracted, the push/pull rod  1616  is pulled axially (or further pulled if partially pulled prior to retraction) to expand stent  1612  to fill the transverse dimension within the body space, e.g., colon, as shown in  FIG.  47 C  to stabilize the chamber. The retractor elements  1552 ,  1554  are moved to the expanded position, bowing outwardly, in the manner described above, e.g., by movement of an actuator operatively connected to the retractor elements  1552 ,  1554  to form the chamber for working instruments. As noted above, the retractor elements  1552 ,  1554  can be expanded before or after proximal movement of the stent structure  1612  toward the distal coupler  1548  and before or after expansion of the stent structure  1612 . 
     Note as an alternative to pull rod  1616 , the catheter  1614  can include a pusher and the stent  1612  is retained in a collapsed position within the catheter  1614 . When the catheter  1614  is moved to the desired site, the pusher is advanced distally to force the stent  1612  out of the distal end of the catheter  1614  to enable it to automatically expand to the expanded position of  FIG.  47 C  due to its spring like characteristics or its shape memory material. 
     In an alternate embodiment, catheter  1614  is axially fixed within catheter  1510  and the stent structure  1612  is therefore axially fixed with respect to the distal coupler  1548 , positioned distally adjacent or overlying coupler  1548 . Thus, in this embodiment, the stent  1612  is in this fixed axial position when collapsed and inserted and remains in the fixed axial position when expanded. 
       FIGS.  49 A and  49 B  illustrate an alternate embodiment wherein the distal balloon forms both the stabilizing structure and the distal coupler. As shown, system  1620  has two flexible elements  1622 ,  1624  attached at their proximal ends to proximal coupler  1626  of catheter  1628 . At their distal ends, flexible elements are attached to stabilizing balloon  1630 . One of the flexible elements  1622 ,  1624  has a lumen for passage of inflation fluid to inflate the balloon  1630 . A C-shaped securement member  1632  can be provided within the balloon  1630  to provide attachment structure for the flexible elements  1622 ,  1624 . In use, the catheter  1628  is inserted with balloon  1630  in the collapsed position of  FIG.  49 A . When at the desired site, the balloon  1630  is inflated and the flexible elements  1622 ,  1624  are expanded (either subsequent or prior to balloon expansion) to the position of  FIG.  49 B , with the balloon  1630  filling the transverse dimension of the body lumen as in  FIG.  43 C  and stabilizing the chamber formed by the flexible elements  1622 ,  1624 . In all other respects, catheter  1628  is the same as catheter  1510  and allows passage of the endoscope and passage of the tool channels and working instruments into the chamber. 
     In the foregoing embodiments of  FIGS.  43 A- 47 C and  49 A- 49 B  having a stabilizing structure, two flexible elements are disclosed to form an asymmetric chamber. It is also contemplated that four flexible elements can be provided to form a symmetric chamber as shown for example in  FIG.  48   . In this embodiment, the four flexible elements  1642 ,  1644 ,  1646 ,  1648  of catheter  1640  are attached at proximal ends to proximal coupler  1654  and with distal ends to distal coupler  1566 . Transverse bridge members  1643  spanning the retractor elements can be provided for stabilization. The flexible elements  1642 ,  1644 ,  1646 ,  1648  are inserted in the collapsed position as shown. When at the desired site, they are expanded to form a substantially symmetric chamber, expanding the wall of the body lumen in opposing directions. A stabilizing element such as the illustrated balloon  1648  attached to catheter  1652  is expandable to stabilize the chamber in the same way as the balloons described above. Alternatively, a mechanical expander as described above instead of a balloon can be utilized to stabilize the chamber. 
     The expansion of the stabilizing structure can occur prior to or after expansion of the retractor elements  1642 ,  1644 ,  1646 , and  1648 . The catheter  1652  can be movable axially to adjust the axial position of the balloon  1648 , or alternatively axially fixed, in the same manner as described above. 
     Note one or more transverse bridges between the flexible elements  1522  and  1524  (or  1642 - 1648 ) can be provided in any of the foregoing embodiments to provide stabilization during bending and facilitate controlled spaced expansion/reshaping. 
     The use of the systems in  FIG.  43 A- 49 B  is shown for removing a lesion, such as a polyp, from a colon wall. However, it should be understood, however, that the systems can be used for other procedures within the colon or the gastrointestinal tract, as well as used for other procedures in other body lumens or body spaces of a patient. 
     Note movement/actuation of the components of any of the embodiments can be robotically controlled including for example expansion of the retractor elements, axial movement of the catheter, expansion of the stabilizer structure and/or inflation of the stabilizer balloon. 
     Referring to  FIG.  36   , the retractor elements of the embodiments disclosed herein forming an asymmetric cage create a working space or working chamber for performance of the surgical procedure. The chamber facilitates instrument maneuverability, for example instruments&#39; triangulation as described above. Note the asymmetric chamber causes a reconfiguration of the body lumen or working space without stretching the body lumen wall beyond a point when it can be injured, e.g., lacerated by the stretching force. Such reconfiguring can be appreciated by reference to  FIG.  36    where the body lumen has changed from a substantially circular cross-sectional configuration to a somewhat oval shape configuration where the walls are elongated as shown. As can be appreciated, this increases the distance from the tips of the working instruments to the targeted tissue, such as the polyp C on the wall of the colon B. Thus, the retractor elements change the colon shape at the desired site to a narrower width, particularly at the bottom of the chamber, and taller in height (in the orientation of  FIG.  36   ) to increase working space for the instruments thereby reconfiguring the colon lumen. 
     The retractor elements of the embodiments disclosed herein also stabilize the luminal wall motion which may be more prominent in the gastrointestinal tract. This may facilitate the surgical procedure, particularly in the gastrointestinal tract. 
     Note that the various embodiments of the cage described above are expandable to alter the working space within the body space or body lumen. As the cage is expanding, the working space around the target tissue, e.g., lesion, is increasing. More specifically, the distance between the instruments and the target tissue is increasing, hence, facilitating the instruments&#39; maneuverability and ability to perform more advanced surgical techniques inside the lumen, e.g., tissue retraction, dissection, repair. As the cage expands it may press on and deflect at least a portion of the luminal wall. As a result, the shape of the lumen can be changed depending on the size and shape of the cage, the extent of its expansion and the size and shape of the body lumen. In smaller diameter body lumens, such as the bowel, the expansion of the cage may substantially reshape the body lumen as described above. This reshaping can also occur in larger diameter body lumens. However, it should also be appreciated that in certain larger diameter body lumens, such as the stomach, and especially when insufflation is utilized for the surgical procedure, the body lumen may not necessarily be reshaped. For example, the cage may only contact one side of the body lumen wall. However, even in this case, the expanded cage applies a radial force against the body wall to alter the working space. Therefore, whether the cage is used in small or larger diameter working spaces/lumens it advantageously moves at least one side of the wall to increase the distance between the tips of the instruments and the target tissue, thereby functioning as a working space expanding system to facilitate access and maneuverability as described in detail above. As can also be appreciated, the dynamic nature of the cage with its controlled expansion enables the system to function as an organizer to adjust and optimize the distance between the tips of the instruments and the target tissue. Also note that in larger diameter body lumens a symmetric cage might also be able to be utilized, although not optimal. 
     Note the endoscopic instruments can be used for partial tissue resection, for example, submucosal or subserosal resection. The endoscopic instruments could also be utilized for full thickness tissue resection. The instruments enable removal of the lesion with healthy tissue margins, thereby providing a complete, en-block removal of the pathological lesion. 
     Without intending to be limited to any theory or mechanism of action, the above teachings were provided to illustrate a sampling of all possible embodiments rather than a listing of the only possible embodiments. As such, it should be appreciated that there are several variations contemplated within the skill in the art that will also fall into the scope of the claims.