Patent Publication Number: US-9839440-B2

Title: Apparatus and methods for internal surgical procedures

Description:
RELATED APPLICATION 
     The present application is a continuation application of U.S. patent application Ser. No. 13/651,972, filed Oct. 15, 2012, and titled APPARATUS AND METHODS FOR INTERNAL SURGICAL PROCEDURES, which is a continuation application of U.S. patent application Ser. No. 11/920,220, filed Apr. 25, 2008, and titled APPARATUS AND METHODS FOR INTERNAL SURGICAL PROCEDURES, which is a U.S. National Stage Application of International Application No. PCT/US2006/018322, filed May 11, 2006, and titled APPARATUS AND METHODS FOR INTERNAL SURGICAL PROCEDURES, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 60/679,760, filed May 11, 2005, and titled APPARTUS AND METHODS FOR INTERNAL SURGICAL PROCEDURES, all of which are hereby incorporated by reference in their entirety. 
    
    
     The present invention relates to internal surgical devices and methods. More particularly, the present invention relates to devices that may beneficially be used in conjunction with, e.g., mucosectomy procedures. 
     A variety of lesions such as superficial tumors, polyps, internal hemorrhoids, etc. may be difficult to remove from internal body locations because they have a relatively low profile with respect to surrounding tissue. The injection of liquids into the submucosa may be performed to facilitate surgical procedures such as, e.g., endoscopic mucosal resection (EMR), polypectomies in the gastrointestinal tract. The injected liquid may advantageously form a submucosal cushion beneath the tissue to be resected. Examples of liquids used to form the submucosal liquid cushion may include, e.g., saline solutions, sodium hyaluronate, glycerol solutions, methylcellulose solutions (such as those described in, e.g., U.S. Patent Application Publication No. 2003/0225460, titled COMPOSITIONS FOR GENERATING SUBMUCOSAL FLUID CUSHIONS, published Dec. 4, 2003), etc. 
     In the absence of a submucosal liquid cushion, it may be difficult for the practitioner to resect large sessile polyps and other lesions without injuring the underlying muscularis propria. By raising the lesion with a submucosal liquid cushion, the lesion may be isolated from the surrounding tissue and the underlying muscularis propria may be better protected from injury during resection of the lesion. 
     After the submucosal liquid cushion is formed, resection may be performed using a snare looped around the base of the submucosal liquid cushion. Examples of snare resection devices are described in, e.g., U.S. Pat. No. 5,542,948 (Weaver et al.) and U.S. Pat. No. 6,210,416 B1 (Chu et al.). Resection using the snare devices is typically augmented by electrosurgical energy to enhance cutting and, in some instances, to reduce bleeding. 
     SUMMARY OF THE INVENTION 
     The present invention provides apparatus and methods for internal surgical procedures. For example, the present invention may involve supporting internal body locations, creating submucosal separations (blebs), and/or for resecting mucosal tissue separated from underlying tissue by a bleb. 
     The apparatus, devices and methods of the present invention may find use in any suitable location within the body in which tissue is to be resected, including, e.g., the colon (to resect polyps or other tissue—with access through, e.g., the rectum), bladder (to resect bladder cancers—access through, e.g., the urethra), etc. In addition, the apparatus, devices and methods of the present invention may also be used to obtain deep muscle biopsies (to, e.g., diagnose neurologic, disorders such as Parkinson&#39;s Disease, gastric motility disorders, etc.). In another potential application, the apparatus, devices and methods of the present invention may be used in transgastric surgical procedures in which instruments are delivered through an endoscope into the stomach. The instruments may then be advanced into the peritoneal cavity through, e.g., the stomach wall where selected surgical procedures could be performed. The apparatus, devices, and methods of the present invention may also be used for purposes not explicitly identified herein. 
     Among the internal surgical apparatus of the present invention, some apparatus that may be used to assist in tissue resection are depicted in  FIGS. 55-57 . The depicted apparatus may be used to prop open a variety of internal body locations, such as, e.g., body lumens (colon, gastro-intestinal, blood vessels, urinary tract, etc.). In connection with blebs, the apparatus of  FIGS. 55-57  may be used to maintain the submucosal space in the absence of, e.g., the gas, liquid, or other material used to create the submucosal space. Various other devices may potentially be advanced into the space defined by the cage, such as, e.g., imaging devices, tissue resection devices, etc. 
     The apparatus and methods for creating blebs may preferably involve the delivery of gas submucosally to separate tissue and create a gas-filled submucosal space. The gas may preferably be delivered at a pressure greater than atmospheric pressure. Using pressurized gas to create gas-filled blebs may provide a number of advantages over blebs formed using liquids. It has been observed that blebs created with pressurized gas may be higher, i.e., the gas-filled submucosal space may potentially be higher when measure normal to the plane of the underlying tissue. It has also been observed that tissue separation within the space of a gas-filled bleb may potentially be more pronounced than within a liquid-filled bleb. 
     Another potential advantage of a gas-filled bleb is that use of an electrosurgical cutting apparatus designed for “inside-out” resection may be more effective when used in connection with a gas-filled bleb. As described herein, some resection devices of the present invention may be effective when used to perform “inside-out” resection of tissue. Unlike conventional mucosal tissue resection in which a cutting instrument is used to cut tissue from the outside of a bleb towards the submucosal space within the bleb, methods of the present invention may preferably involve piercing the tissue of a bleb with a resection device and advancing at least a portion of the resection into the submucosal space. After the resection device (or a portion thereof) is located within the submucosal space, the tissue raised within the bleb can be cut from the inside of the submucosal space outwardly. By directing a cutting action outwardly from within the bleb, cutting and/or perforation of the tissue underlying the bleb may be much less likely to occur. 
     Among the gases that may be used to form gas-filled blebs, it may be preferred that the gas used be carbon dioxide. Potential advantages of carbon dioxide may potentially include, e.g., that carbon dioxide is readily absorbed by tissue and is unlikely to cause embolisms. In addition, carbon dioxide is not flammable and is readily available. More particularly, it may be preferred that the gas used consist essentially of carbon dioxide. It should be understood that small amounts of liquid, such as water, saline, etc., may be entrained within the carbon dioxide so long as the fluid delivered to form a gas-filled bleb is predominantly in the gas phase. 
     In still other embodiments of the present invention, it may be preferred to form a resection barrier of solid materials within the submucosal space of a bleb. By providing a solid resection barrier, conventional cutting instruments such as blades, etc. may be used to remove tissue with a significantly reduced risk of perforating the underlying tissue wall. The resection barrier may be made of a variety of materials including paraffin, curable materials (e.g., cyanoacrylate adhesives), foams, gels, etc. It may be preferred to use paraffin which can be heated to its liquid state and injected into the submucosal space of the bleb, where it cools and hardens to form a resection barrier. 
     In some embodiments, the resection apparatus may preferably include a resection frame located at the distal end of an elongated body. The resection frame preferably supports a cutting instrument that is capable of resecting tissue that extends through a resection opening defined by the resection frame. In some embodiments, the apparatus may preferably include staples and a stapling anvil such that retraction of the resection frame results in both resection of selected tissue and the placement of staples into the remaining tissue to close the edges surrounding the resected tissue. 
     The cutting instrument is preferably located between the two spaced-apart rails of the resection frame. When the resection frame is in an extended position with respect to the elongated body, the cutting instrument may preferably be displaced from the distal end of the elongated body. Movement of the resection frame to its extended position may be described as movement in the distal direction with respect to the elongated body. Movement of the resection frame to a retracted position preferably moves the cutting instrument towards the distal end of the elongated body or otherwise closes the resection opening. In some embodiments, such movement of the cutting instrument may be described as moving the cutting instrument in the proximal direction with respect to the elongated body. 
     When the resection frame is in the extended position, a resection opening may preferably be defined by the two spaced apart rails and the cutting instrument when the resection frame is in the extended position, wherein the size of the resection opening decreases and wherein tissue extending through the resection opening is severed by the cutting instrument when the resection frame is moved into the retracted position from the extended position. 
     It may be preferred that the resection frame include a pair of rails spaced apart from each other. The rails may preferably be rigid members that resist twisting and bending and that also exhibit significant strength in compression along their length as opposed to wires or cables used in snare-type resection devices that exhibit significant strength only in tension and provide only minimal resistance to bending and twisting. 
     The cutting instrument and the spaced apart rails may preferably define a U-shaped resection opening, wherein the U-shaped opening is preferably closed by the distal end of the elongated body. It may, for example, be preferred that the rails be straight and generally parallel to each other. 
     In some embodiments of the invention, the elongated body may include a fluid delivery lumen extending to the distal end of the elongated body, with a needle attached to the fluid delivery lumen at the distal end of the elongated body. It may be preferred that the needle be movable between an injection position in which the needle extends from the distal end of the elongated body and a sheathed position in which the needle is located within the elongated body. 
     An apparatus of the present invention that includes a fluid delivery lumen and needle may further preferably include a fluid source connected to the fluid delivery lumen. The fluid source may provide a fluid as needed to form submucosal fluid cushions in accordance with the preset invention. The fluid provided by the fluid source may be a liquid as is conventionally known. Alternatively, the fluid sources of the present invention may provide a gas to form the submucosal fluid cushion in accordance with the present invention. The gas may be, e.g., carbon dioxide. 
     The use of a resection frame as discussed in connection with the present invention may be advantageous in connection with a gas delivery system for forming blebs. For example, the resection frame may be extended and placed around the tissue to be resected. When in position, the resection frame can be used to apply pressure about the perimeter of the location at which a bleb is to be formed. The pressure provided by the resection frame may serve to restrict the size of the bleb by reducing the likelihood that the gas will separate tissue under the frame. 
     Other resection devices may also be provided in connection with the present invention. Those resection devices may be adapted for use in “inside-out” resection procedures as described herein. Some exemplary embodiments of such devices are described in connection with  FIGS. 11-57  herein. 
     In one aspect, the present invention provides a tissue control device that includes a delivery sheath with a lumen that includes an opening at a distal end of the delivery sheath, wherein the delivery sheath defines a longitudinal axis extending between its distal end and a proximal end; and a cage located within the lumen of the delivery sheath, the cage having a plurality of struts extending from a proximal retainer to a distal retainer, wherein the cage is movable within the lumen such that the cage can be advanced distally out of the distal opening of the lumen. The cage has a restrained configuration when located within the lumen and an expanded configuration when advanced distally out of the lumen, wherein in the expanded configuration the struts move radially outward from the longitudinal axis. 
     In another aspect, the present invention provides a tissue control device for use in internal surgical procedures, the device including a delivery sheath having a lumen that comprises an opening at a distal end of the delivery sheath, wherein the delivery sheath defines a longitudinal axis extending between its distal end and a proximal end; and a cage located within the lumen of the delivery sheath, the cage including a plurality of struts extending in a distal direction from a proximal retainer, wherein the cage is movable within the lumen such that the cage can be advanced distally out of the distal opening of the lumen; wherein the cage has a restrained configuration when located within the lumen and an expanded configuration when advanced distally out of the lumen, wherein in the expanded configuration the struts move radially outward from the longitudinal axis. 
     In another aspect, the present invention provides methods of using the tissue control devices described in the preceding paragraphs by advancing the distal end of the delivery sheath to an internal body location before deploying the cage from the delivery sheath. The plurality of struts preferably move radially outward from the longitudinal axis as the cage is deployed. 
     In another aspect, the present invention provides an endoscopic resection apparatus including an elongated body with a proximal end and a distal end; a resection frame located proximate the distal end of the elongated body, the resection frame including two spaced apart rails, wherein the resection frame has an extended position and a retracted position; a cutting instrument located between the two spaced apart rails of the resection frame, wherein the cutting instrument is displaced from the distal end of the elongated body when the resection frame is in the extended position, and wherein movement of the resection frame to the retracted position moves the cutting instrument towards the distal end of the elongated body; and a resection opening defined by the two spaced apart rails and the cutting instrument when the resection frame is in the extended position, wherein the size of the resection opening decreases and wherein tissue extending through the resection opening is severed by the cutting instrument when the resection frame is moved into the retracted position from the extended position. 
     In another aspect, the present invention provides a method of separating mucosal tissue at a selected location by identifying a selected site in the mucosal tissue of a subject; locating a distal end of a gas delivery lumen submucosally at the selected site; delivering a gas into the mucosal tissue at the selected site through the distal end of the gas delivery lumen, wherein the gas is delivered at a gas pressure greater than the ambient atmospheric pressure, wherein the gas separates the mucosal tissue to create a gas-filled submucosal space. 
     In another aspect, the present invention provides a method of separating mucosal tissue at a selected location by delivering gas into mucosal tissue at a selected site, wherein the gas is delivered at a gas pressure greater than the ambient atmospheric pressure, and wherein the gas separates the mucosal tissue to create a gas-filled submucosal space; and forming a submucosal barrier in the submucosal space by injecting a barrier precursor into the gas-filled submucosal space, wherein the barrier precursor hardens in the submucosal space to form the submucosal barrier. 
     In another aspect, the present invention provides a method of resecting tissue at a selected location by identifying a selected site in the mucosal tissue of a subject; locating a distal end of a fluid delivery lumen submucosally at the selected site; delivering a fluid into the mucosal tissue at the selected site through the distal end of the fluid delivery lumen, wherein the fluid is delivered at a pressure greater than the ambient atmospheric pressure, and wherein a submucosal fluid cushion forms at the selected site; locating a resection device proximate the submucosal fluid cushion, wherein the resection frame is in the extended position, and wherein the submucosal fluid cushion extends through the resection opening; and moving the resection device into the retracted position, wherein the cutting instrument severs tissue raised above the submucosal fluid cushion. 
     In another aspect, the present invention provides a submucosal barrier kit including paraffin; a heating device adapted to beat the paraffin; and a delivery device adapted to deliver heated paraffin to a submucosal location. 
     In another aspect, the present invention provides a mucosal tissue separation kit including a pressurized gas source; and a sterile gas delivery device having a lumen, a tissue-piercing distal end, and a proximal end adapted to receive gas from the pressurized gas source, wherein the lumen extends from the proximal end of the gas delivery device to the distal end of the gas delivery device. Such kits may be supplemented by, e.g., a submucosal barrier precursor and a delivery device adapted to deliver the submucosal barrier precursor to a submucosal location. In other embodiments, the kit may be supplemented by, e.g., paraffin; a heating device adapted to heat the paraffin; and a delivery device adapted to deliver heated paraffin to a submucosal location. 
     In another aspect, the present invention provides a tissue resection device that includes an outer sheath with a distal end, and an outer sheath lumen opening at the distal end and an outer sheath proximal end; an inner sheath adapted to move within the outer sheath lumen, wherein the inner sheath includes a distal end and an inner sheath lumen opening at the distal end of the inner sheath; a core movable within the inner sheath lumen, wherein the core has a distal end; a first resection wire having a distal end attached to the distal end of the core and a proximal end attached to the inner sheath, wherein movement of the distal end of the core towards the distal end of the inner sheath causes a portion of the first resection wire to move radially away from the core; and electrical conductors operably connected to the resection wire, wherein electrical energy can be delivered from the proximal end of the outer sheath to the resection wire. 
     In another aspect, the present invention provides a tissue resection device that includes an elongated body with a distal end and a proximal end; a cutting head attached to the distal end of the elongated body, wherein the cutting head includes a cutting fin having a retracted position wherein the cutting fin is located within the body and an extended position wherein the cutting fin extends from the cutting head; wherein the cutting fin cuts tissue when drawing the elongated body and the cutting head in the proximal direction when the cutting fin is in the extended position. 
     In another aspect, the present invention provides a tissue resection device that includes an elongated body with a distal end and a proximal end; a hinged resection apparatus operably to the distal end of the elongated body, wherein the hinged resection apparatus includes first and second jaws, wherein at least one jaw of the first and second jaws is capable of rotating such that the first and second jaws have an open position in which tissue can be located between the first and second jaws and a closed position in which inner surfaces of the first and second jaws contact tissue located between the first and second jaws; at least one electrosurgical cutting member located on an inner surface of one or both of the first and second jaws, wherein tissue located between the first and second jaws can be cut by the cutting member; and wherein at least one of the first and second jaws includes a tissue piercing jaw, wherein the tissue piercing jaw is capable of piercing tissue when the tissue piercing jaw is advanced distally. 
     In another aspect, the present invention provides a tissue resection device that includes an elongated body having a distal end and a proximal end, wherein the distal end includes a first side and a second side located opposite from the first side; a pair of resection wires extending from the distal end of the elongated body, wherein each of the resection wires has a proximal end attached to the first side of the distal end of the elongated body, and wherein each of the resection wires has a distal end, wherein the distal ends of the resection wires are attached to each other proximate the second side of the distal end of the elongated body. 
     In another aspect, the present invention provides a tissue resection apparatus that includes a tubular body with a channel that opens at a distal end of the tubular body; a spreader sheath with a distal end and a proximal end, a longitudinal axis extending between the distal end and the proximal end of the sheath, wherein the spreader sheath is located within the channel of the tubular body and wherein the spreader sheath is axially movable distally and proximally within the channel of the tabular body; and first and second spreader arms proximate the distal end of the spreader sheath, the first spreader arm and the second spreader arm movable between a closed position in which the first spreader arm and the second spreader arm are aligned with the longitudinal axis and an open position in which the first spreader arm and the second spreader arm each form an angle of at least 15 degrees with the longitudinal axis; wherein the first spreader arm and the second spreader arm are in the closed position when the first spreader arm and the second spreader arm are located within the channel of the tabular body; and wherein the first spreader arm and the second spreader arm move into the open position as the first spreader arm and the second spreader arm are advanced distally out of the channel of the tubular body. 
     In another aspect, the present invention provides a tissue resection device that includes a sheath with a proximal end, a distal end, and a lumen that opens at the distal end of the sheath; and a snare located within the lumen, the snare being axially movable distally and proximally within the lumen, wherein the snare can be advanced distally out of the opening of the lumen; wherein the sheath has an angled tip proximate the distal end of the sheath, the angled tip including a section of the sheath that is oriented off-axis from a longitudinal axis defined by the sheath from its proximal end up to the section of the angled tip. 
     In another aspect, the present invention provides a tissue resection device that includes a sheath with a proximal end and a distal end; a lumen formed in the sheath, wherein the lumen includes a distal opening in a side of the sheath at a location proximal to the distal end of the sheath; and a snare located within the lumen, the snare being axially movable distally and proximally within the lumen, wherein the snare can be advanced distally out of the distal opening of the lumen. 
     In another aspect, the present invention provides a tissue resection device that includes a sheath with a proximal end, a distal end, and a lumen that includes an opening at the distal end of the sheath; a snare located within the lumen, the snare being axially movable distally and proximally within the lumen, wherein the snare can be advanced distally out of the opening of the lumen, wherein the snare includes a pair of wires terminating in a loop proximate the distal end of the sheath, and wherein the wires have rectangular cross-sectional profiles; and a plunger located proximate the proximal end of the sheath, wherein the plunger traverses the lumen in the sheath, and wherein the plunger is located between the pair of wires, the plunger including ribs cooperating with the wires, such that movement of the plunger transverse to a longitudinal axis of the sheath rotates the wires about their respective longitudinal axes, and wherein rotation of the wires causes the snare to curve off of the longitudinal axis of the sheath. 
     In another aspect, the present invention provides a method of providing a tissue resection barrier. The method includes inserting a barrier sheet into a submucosal space of a bleb and deploying the barrier sheet within the submucosal space, wherein the barrier sheet is located between submucosal tissue below the submucosal space and mucosal tissue above the submucosal space. 
     In another aspect, the present invention provides a barrier sheet deployment apparatus that includes a delivery sheath with a lumen that includes an opening at a distal end of the delivery sheath; and a barrier sheet located within the lumen of the delivery sheath, the barrier sheet having one or more coils while in the lumen. 
     These and other potential features and advantages of the present invention may be described below in connection with various exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTIONS OF THE FIGURES 
         FIG. 1  is a cross-sectional view depicting initiation of submucosal fluid cushion formation in accordance with the present invention. 
         FIG. 2  is a partial cross-sectional view depicting formation of a submucosal fluid cushion in accordance with the present invention. 
         FIG. 3  is a perspective view of the distal end of one elongated body that may be used in connection with the present invention. 
         FIG. 4  is a perspective view of the elongated body of  FIG. 3  with a resection frame in the extended position relative to the distal end of the elongated body. 
         FIG. 5  is a partial cross-sectional view of the resection apparatus in position with a submucosal fluid cushion extending through the resection opening. 
         FIG. 6  is a partial cross-sectional view of the resection apparatus of  FIG. 5  with the resection frame in the retracted position such that the tissue can be resected to remove the lesion located above the submucosal fluid cushion. 
         FIG. 7  depicts a stapling apparatus that may be used in connection with the present invention. 
         FIG. 8  is a cross-sectional view of a portion of the stapling apparatus taken along line  8 - 8  in  FIG. 7 . 
         FIG. 9  is a perspective view of one exemplary staple cartridge mat may be used in connection with the present invention. 
         FIG. 10  is a cross-sectional view of a portion of the staple cartridge of  FIG. 9 . 
         FIG. 11  is a partial cut-away side elevational view of one resection device according to the present invention. 
         FIG. 12  is a side elevation of the device of  FIG. 11  with the inner sheath and core extended. 
         FIG. 13  is a side elevation of the device of  FIGS. 11 &amp; 12 , with the core partially retracted. 
         FIG. 14  is a perspective view of a device according to  FIGS. 11-13 , wherein the device includes two resection wires. 
         FIG. 15  is an axial view taken from the distal end proximally of the device of  FIG. 14 . 
         FIG. 16  is a perspective view of the device of  FIGS. 14 &amp; 15  within a bleb. 
         FIG. 17  is a side elevational view of a portion of another resection device according to the present invention. 
         FIG. 18  is a perspective view of the resection device of  FIG. 17  with the cutting member retracted. 
         FIG. 19  is a perspective view of the resection device of  FIG. 17  with the cutting member extended (as in  FIG. 17 ). 
         FIGS. 20-23  are perspective views of one exemplary method of using the resection device of  FIG. 17 . 
         FIG. 24  is a perspective view of a portion of another exemplary resection device with jaws in the open position. 
         FIG. 25  is a side elevational view another exemplary resection device with one rotatable jaw in the open position. 
         FIGS. 26-29  are perspective views of one exemplary method of using the resection device of  FIG. 25 . 
         FIG. 30  is a perspective view of another exemplary embodiment of a resection device according to the present invention. 
         FIGS. 31-33  are side elevational views of one exemplary method of using the resection device of  FIG. 30 . 
         FIG. 34  is a cross-sectional view of one exemplary device for delivering heated paraffin into submucosal space according to the present invention. 
         FIG. 35  is a perspective view of one stick of paraffin that may be used in connection with the device of  FIG. 34 . 
         FIG. 36  is a perspective view of another resection apparatus according to the present invention. 
         FIGS. 37-40  depict various stages in the deployment of the resection apparatus of  FIG. 36 . 
         FIG. 41  depicts one method of use of the resection apparatus of  FIG. 36 . 
         FIGS. 42 &amp; 43  depict another resection device with an angled tip. 
         FIGS. 44-46  depict one method of using the resection device of  FIGS. 42 &amp; 43 . 
         FIG. 47  depicts another resection device. 
         FIGS. 48A-48C  depict another resection device in various configurations. 
         FIGS. 49A-49C  depict cross-sectional views of the wires leading to the snare in the device of  FIGS. 48A-48C . 
         FIGS. 50A-50C  depict one mechanism that may be used to manipulate the wires in the resection device of  FIGS. 48A-48C . 
         FIG. 51  is a cross-sectional view of a bleb with a barrier sheet located therein. 
         FIG. 52  is a partial cross-sectional view of an apparatus that may be used to deliver a barrier sheet. 
         FIG. 53  is a cross-sectional view of the apparatus of  FIG. 52  taken along line  53 - 53  in  FIG. 52 . 
         FIG. 54  is a cross-sectional view of an alternative barrier sheet within the lumen of a delivery sheath. 
         FIG. 55  is a partial cross-sectional view of a portion of an expandable cage delivery apparatus. 
         FIG. 56  is a cross-sectional view of the apparatus of  FIG. 55  taken along line  56 - 56  in  FIG. 55 . 
         FIG. 57  is a view of an alternative expandable cage device. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION 
     In the following detailed description of some exemplary embodiments of the invention, reference is made to the accompanying figures which form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. 
     The present invention may, in various embodiments, include three basic components, an injection apparatus capable of creating a submucosal fluid cushion, a resection apparatus capable of resecting tissue raised above the submucosal fluid cushion, and a stapling apparatus capable of stapling tissue as a part of the tissue removal process. It may be preferred that all three components, i.e., the injection apparatus, resection apparatus, and stapling apparatus be combined in the same instrument as depicted in many of the figures described below. It should, however, be understood that different components may be provided in separate instruments or that two of the components may be integrated into a single instrument. Furthermore, although the apparatus may preferably be adapted for endoscopic delivery, the apparatus of the invention may be introduced by any suitable technique, e.g., surgical, etc. 
     One exemplary apparatus according to the present invention is depicted in  FIG. 1 . The apparatus includes an elongated body  30  that has a distal end  32 . The elongated body  30  may preferably be an endoscope with a suitable number of channels formed therein to accommodate the apparatus of the present invention. 
     The apparatus is depicted as positioned proximate a selected site  14  in tissue that includes mucosa  12  and underlying muscularis propria  10 . The selected site  14  may preferably include a lesion in the form of a tumor, polyp, internal hemorrhoid, etc. that a practitioner would like to resect. 
     The depicted elongated body  30  includes a fluid delivery lumen  24  that extends through at least a portion of the elongated body  30 . It may be preferred that the fluid delivery lumen  24  terminate proximate the distal end  32  of the elongated body  30 . It may also be preferred that the fluid delivery lumen  24  extend proximally towards the proximal end (not shown) of the elongated body  30 . 
     The apparatus depicted in  FIG. 1  further includes a needle  20  that is preferably attached to the fluid delivery lumen  24  proximate the distal end  32  of the elongated body  30 . The needle  20  may preferably be movable between an injection position in which the distal end  22  of the needle  20  extends from the distal end  32  of the elongated body  30  as seen in  FIG. 1 . It may also be preferred that the needle  20  be movable to a sheathed position in which the distal end  22  of the needle  20  does not extend past the distal end  32  of the elongated body  30 , e.g., is retracted within the elongated body  30 . 
       FIG. 2  depicts the apparatus of  FIG. 1  after insertion of the distal end  22  of the needle  20  into the tissue proximate the selected site  14 . It may be preferred that the needle  20  deliver a fluid into the tissue such that the mucosa  12  is separated from the underlying muscularis propria  10  by a submucosal fluid cushion  16 . The fluid used to form the submucosal fluid cushion  16  is preferably delivered through the needle  20 , which is preferably in fluid communication with a fluid source  28  through the fluid lumen  24  extending through the elongated body  30 . 
     The fluid source  28  may take a variety of forms depending on the fluids being supplied. The fluid source  28  may be pressurized such that the fluid can be dispensed through a valve (and preferably pressure regulator) without the need for a separate pump. In other instances, a pumping mechanism may be provided in combination with a reservoir that may or may not be pressurized. The pressure at which the fluid is delivered may vary, although it may be preferred that the pressure for gases be 20 psig (140 kPa) or more. Pressure control may be provided by, e.g., a regulator or other pressure control device. 
     The fluid used to form the submucosal fluid cushion  16  may be liquid, gas, or combination thereof. In some instances, it may be preferred that the fluid used to form the submucosal fluid cushion  16  be a liquid, e.g., saline solutions, sodium hyaluronate, glycerol solutions, methylcellulose solutions (such as those described in, e.g., U.S. Patent Application Publication No. 2003/0225460, titled COMPOSITIONS FOR GENERATING SUBMUCOSAL FLUID CUSHIONS, published Dec. 4, 2003), etc. 
     In other instances it may be preferred that the fluid used to from the submucosal fluid cushion  16  be a gas, e.g., a gas including gaseous carbon dioxide. In other instances, it may be preferred that the fluid consist essentially of one or more gases, e.g., consist essentially of gaseous carbon dioxide. Using a gaseous fluid to form submucosal fluid cushions may have advantages over submucosal fluid cushions formed using liquid fluids as discussed herein. 
     The gases and/or liquids used to form submucosal spaces in blebs may, in some instances, preferably be replaced with solid (i.e., non-flowable) materials to form a resection barrier as discussed herein. Examples of some potentially suitable materials for resection barriers may be paraffin, biocompatible cyanoacrylate adhesive compositions, etc. In still other embodiments, the resection barrier may be provided by gel or polymer-based structural material (e.g., foam, etc.) that, as delivered, is uncured, but that can be expanded/cured, within the submucosal space. In some embodiments, the resection barrier may preferably be biodegradable and/or bioresorbable such that it could slowly erode over time. 
     One potentially suitable expandable material may be a polylactic acid polymer (PLA, e.g., poly-DL-lactide, etc.) which may be provided as a liquid when dissolved in a solvent such as NMP (N-methyl-2-pyrrolidone), but hardens into a pliable structural material when the NMP diffuses out of the polymer mixture. Both NMP and the polymer PLA are generally considered to be inert and bioresorbable for use within the human (or animal) body. Other expandable structural materials may be known to those skilled in the art. 
     In those embodiments in which a fluid is used to create a bleb after which the fluid hardens, solidifies, cures or otherwise becomes non-flowable, the fluid may be referred to as a barrier precursor. In such methods, formation of the submucosal barrier may involve injecting a barrier precursor into the gas-filled submucosal space, wherein the barrier precursor hardens to form the submucosal barrier. Examples of some barrier precursors described herein may include, e.g., heated paraffin (heated, e.g., to a temperature of 65 degrees Centigrade or higher), cyanoacrylate compositions, uncured biocompatible foams, etc. Other barrier precursors may include, e.g., biocompatible photo-curable materials that can be cured upon the application of photo-radiation. 
     The apparatus according to the present invention may also preferably include resection devices to resect tissue raised by forming a submucosal fluid cushion.  FIGS. 3-7  depict one exemplary embodiment of such a resection device and its operation. The resection device may preferably be provided within a housing located at the distal end  32  of the elongated body  30 . As seen in  FIG. 3 , the housing may preferably include an opening  26  into which the needle  20  is retracted when in its sheathed position as discussed above with respect to  FIGS. 1 &amp; 2 . 
     The housing also preferably includes an opening  40  into which a resection frame retracts when in its retracted position. Turning to  FIG. 4 , a resection frame is depicted in an extended position in which the frame extends from the distal end  32  of the elongated body  30 . The resection frame may preferably include two spaced apart rails  42   a  and  42   b  (referred to collectively as rails  42  herein) and a cross-member  50  connecting the two rails  42  at a location spaced from the distal end  32  of the elongated body  30 . 
     Regardless of the exact construction of the resection frame, it may be preferred that the rails  42  and the cross-member  50  define a resection opening  44  located between the cross-member  50  and the distal end  32  of the elongated body  30 . It may be preferred that the rails  42  and the cross-member  50  of the resection frame define a U-shaped resection opening  44 . 
     It may further be preferred that the cross-member  50  include a cutting instrument such that movement of the resection frame to the retracted position (seen in  FIG. 3 ) moves the cutting instrument on the cross-member  50  towards the distal end  32  of the elongated body  30 . As the resection frame is moved from its extended position seen in  FIG. 4  to its retracted position as seen in  FIG. 3 , the size of the resection opening  44  decreases. 
     If selected tissue (such as tissue raised above a submucosal fluid cushion) extends through the resection opening  44  as depicted in  FIG. 5 , that tissue may be resected by the cutting instrument located on the cross-member  50  as seen in  FIG. 6  where the resection frame is nearly completely retracted within the housing at the distal end  32  of the elongated body  30 . It may be preferred that the selected tissue raised by the submucosal fluid cushion include a lesion  14  that is to be removed. 
     The cutting instrument on the cross-member  50  may take any suitable form, e.g., blade, wire, etc. The cutting action of any cutting instrument may be supplemented by, e.g., electrical energy (e.g., the cutting instrument may be an electrosurgical device). 
     It may be preferred that resection frames of the present invention be constructed with rails  42  that are rigid members. As used herein, a rigid member is a structure that resists twisting and bending and that also exhibits significant strength in compression along its length as compared to wires or cables used in snare-type resection devices (that exhibit significant strength only in tension and provide only minimal resistance to bending and twisting). It may further preferred that the tails  42  of resection frames of the present invention be straight and arranged generally parallel to each other. 
       FIGS. 7 &amp; 8  depict a portion of the resection device to further describe an additional optional feature of the present invention. The resection frame including rails  42   a  and  42   b  and cross-member  50  are seen  FIG. 7 . The depicted cross-member  50  includes a blade  52  as a cutting instrument as seen in  FIG. 8 . 
     The cross-member  50  also preferably includes anvil surfaces  54  adapted to interact with staples  60  retained proximate the distal end  32  of the elongated body. The interaction between anvil surfaces  54  and the staples  60  preferably results in stapling of the tissue captured within the resection frame such that after removal of the tissue resected by the blade  52 , the edges of the remaining tissue are held together by staples  60 . The resection and stapling actions may preferably occur substantially at the same time as the resection frame is moved from its extended position towards its retracted position (in the direction of arrows  48  in  FIG. 8 ). With the staples  60  and the stapling anvil  54  located on opposite sides of the resection opening when the resection frame is in the extended position, movement of the resection frame into the retracted position as discussed herein preferably forces the staples  60  into contact with the stapling anvil  54 . The staples  60  and the stapling anvil  54  cooperate to staple tissue extending through the resection opening when the resection frame is moved into the retracted position from the extended position. 
     Although staples  60  are shown as being deformed by anvil surfaces  54 , it will be understood that in some devices according to the present invention, the staples may be deformed by other mechanisms, e.g. the staples may be formed of shape memory materials (e.g., Nitinol, etc.) that deform in the absence of physical force. 
       FIGS. 9 &amp; 10  depict another optional feature that may be incorporated into the apparatus of the present invention in the form of a staple cartridge capable of storing multiple sets of staples for delivery to multiple resection sites. The cartridge  70  includes staples  60  located in two channels  72  and  74 . Although the cartridge  70  includes only two channels, it should be understood that cartridges according to the present invention may include more than two channels of staples. 
     The staples  60  may preferably be arranged within each of the channels  72  and  74  such that they are canted at an acute angle with respect to the longitudinal axis  73  of the channel (see  FIG. 10 ). Each channel may also preferably include a member  76  adapted to bias the staples  60  towards the open end of the channel. The member  76  may be biased in the direction of the staples by a resilient member (e.g., spring, elastomeric article, etc.), hydraulic or pneumatic pressure, ratcheting mechanism, etc.). The member  76  may be used to advance the staples  60  toward the opening in the channel as staples  60  are dispensed from the cartridge  70 . 
       FIGS. 11-16  depict another resection device that may be used in connection with the present invention. The resection device  100  may preferably be used in connection with an “inside-out” resection procedure as described herein. 
     The device  100  includes an outer sheath  102 , an inner sheath  104  and an core  106 . The inner sheath  104  and the outer sheath  102  are movable axially (i.e., along their lengths) with respect to each other with, e.g., the inner sheath  104  moving within a lumen of the outer sheath  102 . The core  106  is axially movable with respect to the inner sheath  104  within a lumen in the inner sheath  104 . 
     The device  100  also preferably includes one or more resection wires  108  provided to cut tissue. The depicted device includes two resection wires  108 , although devices of the invention may include only one resection wire or three or more resection wires. The resection wires  108  are attached to the distal end  107  of the core  106 . The proximal ends of the resection wires  108  are attached to the inner sheath  104 , preferably proximate the distal end  105  of the inner sheath  104 . Alternatively, the proximal ends of the resection wires  108  may be attached to the outer sheath  102  so long as the resection wires  108  do not significantly interfere with advancement of the outer sheath to a selected resection site. 
     The resection wires  108  may preferably cut tissue with the use of electrical energy delivered to the wires in accordance with known electrosurgical techniques. As such, it may be preferred that the device  100  include conductors that extend from the proximal end of the device (not shown) to the distal end (shown). The conductors may take the form of wires, electrical traces formed in or on the sheaths, etc. 
     As seen in  FIG. 11 , it may be preferred that the inner sheath  104 , core  106  and resection wires  108  be retracted within the outer sheath  102  during advancement of the device  100  to a selected location. Once in position, the outer sheath  102  and inner sheath  104  are preferably manipulated such that the inner sheath  104  extends out of the outer sheath  102  (see, e.g.,  FIG. 12 ). 
     When the core  106  is fully extended out of the inner sheath  104 , the resection wires  108  are preferably in close proximity to the core  106 . As, however, the distal end  105  of the core  104  and the distal end  107  of the core  106  are moved together, the resection wires  108  preferably move radially outward from the core  106  as seen in  FIGS. 12 &amp; 13  because their ends are fixedly attached to the inner sheath  104  and the core  106 . 
     In the device  100  which includes two resection wires  108 , it may be preferred that the wires  108  be offset circumferentially about the core  106 , as is perhaps best seen, in  FIGS. 14 &amp; 15 . The offset between resection wires  108  may be measured in degrees and it may be preferred that the resection wires  108  be offset by an angle α (alpha) of about 30 degrees or more, 45 degrees or more, or even 90 degrees or more. 
       FIG. 16  depicts the device  100  deployed within the submucosal space of a bleb. The device  100  is preferably capable of piercing the tissue forming the bleb such that the core  106  with resection wires  108  can be deployed within the submucosal space. Once in position, the core  106  and inner sheath  104  are preferably manipulated such that the resection wires  108  extend radially outward from the core  106  to contact and cut the separated mucosal tissue. As discussed herein, it may be preferred that electrical energy be provided to the wires  108  to assist in the cutting. 
     In some embodiments, it may be preferred that the resection wires  108  be constructed of a shape memory metal (e.g., nickel titanium alloys, etc.) such that the shape of the resection wires  108  can be further modified based on the temperature of the wires  108 . For example, if the wires  108  heat up during an electrosurgical procedure, that temperature increase can be advantageously used to provide additional height to the wires  108  or to cause the wires  108  to take on different selected shapes. 
       FIGS. 17-23  depict another resection device that may be used in connection with the present invention. The resection device  200  may also preferably be used in connection with an “inside-out” resection procedure as described herein. 
     The device  200  includes an elongated body  202  having a distal end  203 . A cutting head  210  is attached to the distal end  203  of the elongated body  202 . The cutting head  210  preferably includes a cutting member  212  that may preferably be in the form of a fin as seen in  FIG. 17 . The cutting member  212  preferably includes an edge  214  adapted to cut tissue. To assist in delivery and selective cutting of tissue, it may be preferred that the cutting member  212  be retractable such that the edge  214  can be withdrawn into the cutting head during, e.g., delivery of the device  200  to a selected location (see  FIG. 18  which depicts device  200  with cutting member  212  retracted into cutting head  210 ). In the depicted embodiment, the cutting member  212  preferably rotates about pin  211  in cutting head  210 . 
     The cutting member  212  may preferably be adapted for use as an electrosurgical cutting device in which electrical energy is provided to assist the cutting edge  214  in cutting tissue. It may be preferred that conductors be operably connected to the cutting member  212  to provide the electrical energy to the cutting member  212 . The conductors preferably extend proximally along elongated body  202  to an electrical power source. 
     The cutting head  210  may also preferably include a puncture wire  216  or other piercing structure to assist the device  200  in piercing the tissue forming a bleb. The puncture wire  216  may preferably be a relatively thick monofilament polymer or other structure. The puncture wire  216  (or other structure) may preferably be retractable within the cutting head  210  to prevent unwanted piercing of tissue as the elongated body  202  is advanced to the selected location. 
       FIGS. 20-23  depict use of the device  200  in connection with a bleb. In  FIG. 20 , the device  200  is advanced such that the puncture wire  216  pierces the tissue of the bleb. The cutting member  212  may preferably be in the retracted position within the cutting head  210  as seen in  FIG. 20 . 
       FIG. 21  depicts the device  200  after insertion into the bleb, with the cutting head  210  fully inserted into the submucosal space formed within the bleb. The puncture wire  216  is depicted as retracted back within the cutting head  210 , although the puncture wire  216  may not necessarily have to be retracted at this point in the procedure. 
       FIG. 22  depicts the device  200  in which the cutting member  212  has been extended from the cutting head  210 . The cutting member  212  is also depicted as having initiated a cut into the tissue of the bleb.  FIG. 23  depicts the cutting head  210  in the submucosal space after the elongated body  202  and attached cutting head  210  with cutting member  212  have been withdrawn in the proximal direction (i.e., moving out of the bleb through the opening formed during insertion) such that a portion of the tissue forming the bleb has been cut. After a desired amount of tissue has been cut, the cutting head  210  may be repositioned within the submucosal space for another cutting action. 
       FIGS. 24-29  depict another resection device that may be used in connection with the present invention. The resection device may also preferably be used in connection, with, an “inside-out” resection procedure as described herein. 
       FIG. 24  is a perspective view of one resection device  300 ′ that includes an elongated body  302 ′ with a cutting head at the distal end that includes jaws  310 ′ and  312 ′, both of which may preferably be hinged about an axis  311 ′. The jaw  310 ′ preferably includes a cutting member  320 ′ on the inner surface  321 ′ and the jaw  312 ′ preferably includes a cutting member  322 ′ on its inner surface  323 ′. In some devices, it may be sufficient to provide a cutting member in only one of the jaws while the other jaw may provide, e.g., a surface against which the opposing jaw acts during the cutting. Furthermore, although the jaws  310 ′ and  312 ′ include cutting members  320 ′ and  322 ′ in the form of a single blade, it should be understood that the cutting member or members used in connection with the present invention may take any desired form or shape that provides the desired tissue resection. 
     The cutting members  320 ′ and  322 ′ may preferably employ electrical energy in an electrosurgical cutting action to assist with tissue resection as is known in the art. If electrical energy is used in the cutting, conductors may preferably be provided to deliver the required electrical energy to the cutting members. The electrical conductors may preferably extend along the elongated body from a proximal end (not shown) to the distal end. 
     One feature depicted in connection with resection device  300 ′ is that both jaws  310 ′ and  312 ′ are hinged or otherwise capable of rotation with respect to the elongated body  302 . In a variation on resection device  300 ′, only one of the jaws may be hinged for rotation. One such embodiment is depicted in  FIGS. 25-29 . In that embodiment, the resection device  300  includes a jaw  310  that preferably does not rotate relative to the distal end  303  of elongated body  302 . The opposing jaw  312  does, however, preferably rotate about axis  311  such that the jaws  310  and  312  can be moved from an open position (seen in  FIG. 25 ) to a closed position (see in  FIG. 27 ) in which the jaws are brought together to cut tissue located therebetween. 
     It may be preferred mat one or both of the jaws  310  and  312  of device  300  have a shape or structure such that the jaw or jaws can pierce tissue, e.g., the tissue forming a bleb. In the depicted embodiment, jaw  310  preferably includes a tip  314  distal from the elongated body  302  that is preferably adapted to pierce tissue. In some instances, the tissue piercing may be assisted by electrosurgical energy and in other instances, the piercing may be a purely mechanical action. 
       FIG. 26  depicts device  300  in use in which the jaw  310  of device  300  is inserted into a bleb using the tissue piercing tip  314 . The jaw  312  is preferably rotated away from jaw  310  such that the jaws are in the open position. As the device  300  is advanced distally, more of the jaw  310  is inserted into the submucosal space of the bleb. 
       FIG. 27  depicts the jaws  310  and  312  of the device  300  in the closed position such that, tissue located between the inner surfaces of the jaws  310  and  312  can be cut.  FIG. 28  depicts the bleb with an incision formed therein after removal of the device  300 .  FIG. 29  depicts the device  300  repositioned relative to the bleb to, e.g., cut the other side of the bleb to assist in removal of the tissue raised within the bleb. 
       FIGS. 30-33  depict another resection device that may be used in connection with the present invention. The device  400  includes an elongated body  402  and a cap  410  attached to the distal end  403  of the elongated body  402 . The cap  410  may preferably be in the form of a scoop with two edges that include cutting members  412 . The cutting members  412  may preferably include proximal ends attached to one side of the distal end  403  of the elongated body  402 . The cutting members  412  also preferably include distal ends attached to the cap  410 , wherein the distal ends converge at the tip  414  of the cap  410 . 
     The cutting members  412  may preferably employ electrical energy in an electrosurgical cutting action to assist with tissue resection as is known in the art. If electrical energy is used in the cutting, conductors may preferably be provided to deliver the required electrical energy to the cutting members. The electrical conductors may preferably extend along the elongated body from a proximal end (not shown) to the distal end  403 . It may be preferred that the cutting members  412  located on opposite sides of the cap  410  be electrically isolated from each other such that the cutting action of each cutting member  412  (if electrosurgically enhanced) can be independently controlled. 
       FIGS. 31-33  depict the device  400  in use resecting tissue raised within a bleb. The general scoop shape of the cap  410  may preferably assist in retaining the tissue in contact with the cutting members  412  attached to the cap  410  in a manner similar to a shovel. It may be preferred that the cap  410  include a relatively sharp tip  414  to assist in initial penetration and piercing of the tissue of the bleb. 
     A discussed herein, it may be beneficial to provide a resection barrier within the submucosal space of a bleb. Resection barriers may be used in connection with conventional resection devices and/or at least some of the resection devices of the present invention. 
     In one exemplary embodiment, the resection barrier may be formed by injecting heated paraffin into the submucosal space of a bleb and allowing the paraffin to cool to a point at which it solidifies.  FIG. 34  depicts one potential apparatus for delivering the heated paraffin to the submucosal space and  FIG. 35  is a perspective view of one stick  520  of paraffin that may be used with the device of  FIG. 34 . 
     The paraffin used in connection with the present invention may preferably be sterile medical grade paraffin. Medical grade paraffin has a melting point at 65 degrees Celsius and cools/solidifies rapidly when placed in contact with tissue. In addition, it may be desirable to incorporate one or more agents into the paraffin to, e.g., decrease the melting point (such as an emulsifier), increase visibility (e.g., a colorant), etc. 
     The device  500  is in the general form of a conventional hot glue gun and may preferably include a heating chamber  502  and a plunger  504  adapted to force paraffin out of the heating chamber  502  through an orifice  506 . The heated paraffin then preferably passes through a channel  507  to a port  508 . 
     A delivery device  510  (preferably in the form of e.g., a needle) is preferably attached to the port  508 . The delivery device  510  preferably includes a lumen through which the heated paraffin travels to a distal end  512 . It may be preferred that the distal end  512  of the delivery device be adapted to pierce tissue such as, e.g., the tissue of a bleb. 
     It may be preferred that the delivery device  510  include means for providing heat to the lumen such that the temperature of the heated paraffin passing through the lumen is maintained at a level that prevents solidification of the paraffin within the lumen (thus preventing delivery of the heated paraffin to the submucosal space). In some instances, the means for heating may be provided by electrical resistance heaters, fluid chambers adapted to receive heated fluid pumped to the delivery device, RF or microwave heat elements adapted to convert RF or microwave energy to thermal energy, etc. As an alternative to beating the lumen, the delivery device may preferably include sufficient insulation around the lumen such that the heated paraffin does not solidify during normal use of the device. 
       FIGS. 36-40  depict another apparatus that may be used to remove tissue. The tissue to be removed may or may not be raised using a submucosal cushion formed using gas, liquid, or solid material as described herein. 
     The apparatus  600  includes a tubular body  610  that includes a distal end  612  and a proximal end (not shown). In use, the distal end  612  is preferably advanced to the tissue to be resected while the proximal end preferably remains outside the body of the patient where it can be manipulated. The tubular body  610  may preferably be, e.g., an endoscope. The tubular body  610  preferably includes a channel in which a spreader sheath  620  is located. The spreader sheath  620  preferably includes a lumen in which a resection device  630  is located. The lumen extends along the length (longitudinal axis) of the sheath  620  and includes an opening at the distal end of the spreader sheath  620 . The resection device  630  is axially movable distally and proximally within the lumen, in the spreader sheath  620 , such that the resection device  620  can be advanced distally out of the opening of the lumen of the spreader sheath  620 . 
     A perspective view of the spreader sheath  620  in its deployed configuration with a resection device in the form of a snare  640  advanced through its own sheath  630  is depicted in  FIG. 36 .  FIGS. 37-40  depict the apparatus  600  in successive stages of deployment. Turning to  FIG. 36 , the spreader sheath  620  includes a distal end (shown) and a proximal end (not shown). The distal end of the spreader sheath  620  preferably includes spreader arms  622  and  624  movable between a closed position in which the spreader arms are aligned with the longitudinal axis  602  (see  FIG. 37 ) and an open position (as depicted in, e.g.,  FIG. 40 ) in which the spreader arms  622  and  624  each form an angle β (beta) with the longitudinal axis  602 . It may be preferred that the angle formed by each spreader arm  622  and  624  with the longitudinal axis  602  be at least 15 degrees, in some instances at least 30 degrees, and in other instances at least 45 degrees. 
     The spreader arms  622  and  624  may be located in the closed position while within the channel of the tabular member  610  as depicted in, e.g.,  FIG. 37 . It may be preferred that axial movement of the spreader sheath  620  along the longitudinal axis  602  in the distal direction out of the tubular member  610  allows the spreader arms  622  and  624  to assume the open configuration as depicted m the series of  FIGS. 37-40 . In the open configuration, it may be preferred, for example, that the spreader aims  622  &amp;  624  have a length of about 1.5 centimeters while the spreader sheath  620  proximal of the spreader arms  622  and  624  have a size of 10 French. The spreader arms  622  &amp;  624  may preferably open to an included angle of 90 degrees or more (with each spreader arm moving to a position of 45 degrees off of the longitudinal axis defined for the device). 
     It may be preferred that the spreader aims  622  and  624  are biased in the open configuration when not constrained within the channel of the tubular member  610 . The biasing may be performed by a biasing means such as, e.g., elastic members, shape memory materials (e.g., nickel titanium alloys, polymers, etc.), mechanical springs (e.g., leaf, coil, etc.), pistons, etc. It may be preferred that the spreader arms  622  and  624  move back into the closed position when the sheath  620  is withdrawn axially back within the tabular member  610  (in the proximal direction). 
     Although both spreader arms  622  and  624  are depicted as moving equally from the closed to the open position in  FIGS. 36-40 , it should be understood that the spreader arms  622  and  624  may not move equally in all embodiments. In some embodiments, for example, only one spreader arm may move from the closed to open position, with the other arm remaining stationary. 
     Also depicted in connection with the embodiment of  FIGS. 36-40  is a resection device in the form of a snare  640  that is delivered through its own sheath  630 . The snare  640  is, in the depicted embodiment, preferably advanced distally through a lumen in the spreader sheath  620  while in its own sheath  630 . In use, the snare sheath  630  may be advanced out of the spreader sheath  620  as seen in, e.g.,  FIG. 39 , followed by advancement of the snare  640  in the distal direction out of the snare sheath  630  as seen in, e.g.,  FIGS. 36 &amp; 40 . The snare  640  may preferably include two arms  642  and  644  that are connected at the distal end  646  of the snare  640 . If desired, the snare  640  may perform tissue resection with the aid of electrosurgical energy. 
     One potential use for the apparatus of  FIGS. 36-40  is in a polypectomy in which the polyp is located, e.g., just above or beyond a haustral fold in the colon. One such situation is depicted in  FIG. 41 . Although some techniques using existing resection devices have been used to resect such tissue, some polyps nevertheless remain difficult to remove. When using the apparatus of  FIGS. 36-40 , however, the spreader arms  622  &amp;  624  may be used to push a haustral fold down and keep it in that position, clearing the view to the polyp and allowing the snare  640  to more easily encircle the polyp. The apparatus of  FIGS. 36-40  could also be used to hold haustral folds down to explore their backsides to determine whether additional polyps might be located there. 
       FIGS. 42-46  depict another resection device that may be used to remove tissue. The tissue to be removed may or may not be raised using a submucosal cushion formed using gas, liquid, or solid material as described herein. 
     As depicted in  FIG. 42 , the resection device  700  may include a sheath  710  having both a distal end  712  and a proximal end  714 . The sheath  710  preferably includes a lumen that opens at the distal end  712 . 
     The device  700  also preferably includes a snare  720  located within the lumen of the sheath  710 . The snare  720  is preferably axially movable distally and proximally within the lumen of the sheath  710 . such that the snare  720  can be advanced distally out of the opening of the lumen at the distal end  712  of the sheath  710 . 
     The sheath  710  preferably includes an angled tip proximate the distal end  712  of the sheath  710 . The angled tip includes a section  716  of the sheath  710  that is oriented off-axis from a longitudinal axis  702  defined by the sheath  710  from the proximal end  714  up to the section that includes the angled tip. The section  716  of the sheath  710  that includes the angled tip may preferably include 10% or less of the total length of the sheath  710  from the proximal end  714  to the distal end  712 . 
     As a result of the angled tip, it may be preferred that the snare  720 , when advanced distally out of the distal end  712  of the sheath  710 , exit the sheath  710  at an angle θ (theta) that may preferably be 20 degrees or more off of the longitudinal axis  702  (as depicted in  FIG. 43 ). Although the section  716  of the sheath forming the angled lip is depicted as being generally straight along its length, it should be understood that it could be curved or constructed of multiple sections that are straight and/or curved. Regardless, it is preferred that the snare  720  exit the sheath  710  at an angle off of the longitudinal axis  702  as discussed herein. 
     Potential advantages of the angled tip may include, e.g., enhanced stiffness in the snare  720  as it exits the sheath  710  as compared to a conventional sheath in which the snare exits the sheath along the longitudinal axis of both components (i.e., the sheath and the snare). This additional, stiffness in the snare may improve the ability of the snare to encircle polyps or other tissues as depicted in the series of  FIGS. 44-46 . 
     Another embodiment of a resection device that may be used to remove tissue is depicted in  FIG. 47 . The tissue to be removed may be raised from the surrounding tissue (as in the case, e.g., of a polyp). In some instances, the tissue may or may not be raised using a submucosal cushion formed using gas, liquid, or solid material as described herein. 
     The resection device  800  may include a sheath  810  having both a distal end  812  and a proximal end  814 . The sheath  810  preferably includes a lumen  816  that opens through the side of the sheath  810  at a location proximal from the distal end  812  of the sheath  810 . The sheath  810  itself, however, preferably extends along the longitudinal axis  802  defined between its distal and proximal ends  812  and  814 . In contrast, a distal section of the lumen  816  proximate the distal side opening is oriented off-axis from the longitudinal axis defined between the proximal and distal ends  812  and  814  of the sheath  810 . It may be preferred that the side opening in the lumen be located within the distal-most 10% or less of the total length of the sheath  810  (as measured between its proximal and distal ends  812  &amp;  814 ). 
     The device  800  also preferably includes a snare  820  located within the lumen  816  of the sheath  810 . The snare  820  is preferably axially movable distally and proximally within the lumen  816  such that the snare  820  can be advanced distally out of the opening of the lumen  816  through the opening in the side of the sheath  810 . 
     Because the snare  820  exits the sheath  810  through its side, the snare  820  preferably forms an angle λ (lambda) with the longitudinal axis  802  that may preferably be 20 degrees or more off of the longitudinal axis  802 . Potential advantages of the angled snare  820  may include, e.g., enhanced stiffness in the snare  820  as it exits the sheath  810  as compared to a conventional sheath in which the snare exits the sheath along the longitudinal axis of both components (i.e., the sheath and the snare). This additional stiffness in the snare  820  may improve the ability of the snare to encircle polyps or other tissues. 
     Still another embodiment of a resection device is depicted in  FIGS. 48A-48C, 49A-49C, and 50A-50C . Turning to  FIGS. 48A-48C , the resection device  900  is in the form of a sheath  910  that includes a lumen in which a snare  920  is located. The sheath  910  includes both a distal end  912  and a proximal end  914 . The lumen in the sheath  910  preferably opens at the distal end  912  of the sheath. 
     The snare  920  is preferably axially movable distally and proximally within the lumen of the sheath  910 , such that the snare  920  can be advanced distally out of the opening of the lumen at the distal end  912  of the sheath  910 . It may be preferred that the snare  920  be movable from orientations in which the snare  920  lies substantially within a plane  904  in which the longitudinal axis defined by the distal end  912  and proximal end  914  of the sheath  910  lies as seen in  FIG. 48A . Manipulation of the as described herein can, however, cause the snare  920  to curve above or below the plane  904 . For example,  FIG. 48B  depicts the snare  920  curving away from the plane  904  in one direction while  FIG. 48C  depicts the snare  920  curving away from the plane  904  in the opposite direction. 
     Movement of the snare  920  between the positions depicted in  FIGS. 48A-48C  may be effected by manipulating the wires  922  and  924  of the snare within the lumen  916  of the sheath  910 .  FIGS. 49A-49C  depict the orientation of the wires  922  and  924  within the lumen  916  at a position between the distal end  912  and the proximal end  914  of the sheath  910 . As seen in  FIG. 49A , the wires  922  and  924  are in a neutral orientation within the lumen  916 . In  FIG. 49B , the wire  922  is rotated clockwise about its axis while wire  924  is rotated counterclockwise. The result is depicted in  FIG. 48B  in which the snare  920  curves upward from the plane  904 . In  FIG. 49C  the wires  922  and  924  are rotated in the opposite direction, i.e., wire  922  is rotated counterclockwise from the neutral position of  FIG. 49A  and wire  924  is rotated clockwise. The result is depicted in  FIG. 48C  in which the snare  920  curves downward with respect to the plane  904 . 
       FIGS. 50A-50C  depict one apparatus that may be used to rotate the wires  922  and  924  as discussed herein to control the orientation of the snare  920 . The apparatus includes a plunger  930  that may preferably be located proximate the proximal end  914  of the sheath  910 . The depicted plunger  930  traverses the lumen  916  of the sheath  910  and is located between the wires  922  and  924 . The plunger  930  may preferably include ribs  932  that cooperate with the wires  922  and  924  such that movement of the plunger  930  transverse to the longitudinal axis  902  (out of the page in  FIGS. 50A-50C ) rotates the wires  922  and  924  about their respective longitudinal axes. 
     Although  FIGS. 50A-50C  depict one mechanism for rotating the wires  922  and  924 , many other mechanisms that accomplish the same function may be used in place of that depicted in  FIGS. 50A-50C . 
       FIGS. 51-54  depict another exemplary apparatus and method of the present invention in which a barrier sheet is deployed within the submucosal space of a bleb.  FIG. 51  in particular depicts (in partial cross-sectional view) a barrier sheet  1070  located within the submucosal space  1002  that may preferably be located beneath, e.g., a polyp  1004  or other tissue to be resected. The barrier sheet  1070  may preferably include a central area  1072  and a raised lip  1071  that may preferably extend about a periphery of the central area  1072 . The lip  1071  may be integrally formed with the material of the central area  1072  or it may be attached thereto. Furthermore, the lip  1071  may extend continuously about the perimeter of the central area  1072  or it may be discontinuous. 
     The barrier sheet  1070  is provided to act as a barrier to protect the underlying submucosal tissue during resection procedures. It may be preferred that conventional cutting instruments such as blades, etc. that may be used to remove tissue cannot readily perforate or cut the barrier sheet  1070 . As a result the barrier sheet  1070  may preferably significantly reduce the risk of perforating an underlying tissue wall. Other potential functions of the barrier sheet  1070  may include, e.g., reducing diffusion of any gas, liquid, foam, etc. introduced into the tissue underlying the barrier sheet, providing a tactile response to the practitioner during resection (thus providing, e.g., an indication of the location of the bottom of the submucosal space or the edges of the space—using, e.g., the optional lip  1071 ), etc. 
     In some instances, it may be preferred that the barrier sheets of the present invention be manufactured of one or more materials that exhibit shape memory properties. For example, it may be preferred that the lip  1071  of the barrier sheet  1070  be manufactured of shape memory materials while the central area  1072  may be manufactured of materials that may or may not exhibit shape memory properties. Alternatively, the central area  1072  may be manufactured of shape memory materials while the lip  1071  is manufactured of materials that may or not exhibit shape memory properties. Barrier sheets manufactured of two or more different materials may be manufactured by a variety of techniques, e.g., coextrusion, coinjection molding, insert molding, etc. 
     Delivery of the barrier sheet  1070  info the submucosal space  1002  may be accomplished by any suitable technique. One exemplary apparatus and technique may be described in connection with  FIGS. 52-54 . Generally, it may be preferred to deliver the barrier sheet  1070  using a catheter-like device in which the barrier sheet  1070  is coiled. Delivery may, therefore be accomplished by pushing or ejecting the barrier sheet  1070  and allowing it to uncoil within the submucosal space  1002 . 
     The coiled barrier sheet  1070  may preferably be located proximate a distal end  1012  of a delivery sheath  1010  as depicted in, e.g.,  FIG. 52 . As a result, the barrier sheet  1070  is preferably located within a lumen  1020  of the delivery sheath  1010  when inserting the barrier sheet  1070  into the submucosal space  1002 . During deployment of the barrier sheet  1070 , it may be moved out of the lumen  1020  of the sheath  1010  through an opening at the distal end of the delivery sheath  1010 . Because the barrier sheet  1070  is restrained in its coiled configuration while in the lumen  1020 , ejecting the barrier sheet  1070  from the lumen  1020  results in uncoiling the barrier sheet  1070  within the submucosal space  1002 . 
     Although many different techniques may be used to move the barrier sheet  1070  out of the lumen  1020 , one exemplary method depicted in  FIG. 52  includes an ejection device  1030  that may preferably advance toward the distal end  1012 , forcing the barrier sheet  1070  out of the lumen  1020  using surface  1082  as it advances distally (i.e., in the distal direction of the sheath  1010 ). The ejection device  1080  may preferably be operably connected to an actuator  1084  that may preferably be located proximate the proximal end  1014  of the delivery sheath  1010 . 
     Another optional feature depicted in  FIG. 52  is that the distal end  1012  of the sheath  1010  may preferably be adapted to pierce or perforate tissue, such as the tissue of a bleb, such that the opening of the lumen  1020  is located within the submucosal space where the barrier sheet  1070  can be deployed. Alternatively, the sheath  1010  may be inserted into the submucosal space through a variety of other techniques and/or apparatus. 
     It should be understood that the depicted sheath, ejection device, actuator, etc. depicted in  FIG. 52  are exemplary in nature only and that any suitable apparatus or mechanism that can deliver and deploy the barrier sheets of the present invention may be used. 
     Another variation in connection with the barrier sheets of the present invention may be depicted in  FIGS. 53 &amp; 54 . In particular,  FIG. 53  is a cross-sectional view of barrier sheet  1070  and sheath  1010  taken along line  53 - 53  in  FIG. 52 . The barrier sheet  1070  includes only one coil when located within lumen  1020 . Alternatively, the barrier sheets of the present invention may be stored within the lumen of delivery sheath in a variety of other configurations. One such alternative is depicted in the cross-sectional vie of  FIG. 54  in which barrier sheet  1170  includes two coils  1174  &amp;  1176  when located within lumen  1120  of sheath  1110 . The coils  1174  &amp;  1176  may preferably be rolled inwardly towards each other in opposing directions as depicted. A potential advantage of a two-coil configuration is that uncoiling of the barrier sheet  1170  within a submucosal space may be facilitated with two smaller coils such as are depicted in  FIG. 54 . 
     The barrier sheets of the present invention may be manufactured of a variety of different materials, although the materials may preferably possess the functional characteristics discussed herein (such as, e.g., flexibility and memory sufficient to allow for coiling and uncoiling). In some embodiments, the barrier sheets may preferably be constructed of biosorbable materials. Some exemplary materials may include, e.g., films, woven fabrics, non-woven fabrics, laminates of films and/or fabrics, etc. The materials may include, e.g., GORE-TEX fabrics, polypropylene, polyurethane, etc. It may be preferred that the materials used to construct the barrier sheets resist electro-cautery currents (e.g., possess low electrical conductivity). Examples of some suitable materials may be described in, e.g., U.S. Patent Application Publication No. US 2002/0161114 A1 (Gunatillake et al.,), U.S. Pat. No. 6,080,474 (Oakley et al.), U.S. Pat. No. 6,021,524 (Wu et al.), and U.S. Pat. No. 5,368,930 (Samples). 
     The thickness of the materials used for barrier sheets of the present invention may preferably be, e.g., 1 millimeter or less (although in some instances, the thickness may be greater, e.g., for use in laparoscopic procedures). The overall size of the barrier sheets may also be dependent on the needs of a selected procedure, e.g., in some instances, the barrier sheets may be 10 centimeters or more across and in other procedures, the barrier sheets maybe 1 centimeter or less across. 
     Still another apparatus that may be used to assist in tissue resection is depicted in  FIGS. 55 &amp; 56 . The depicted apparatus may be used to prop open a variety of internal body locations, such as, e.g., body lumens (colon, gastro-intestinal, blood vessels, urinary tract, etc.). In connection with blebs, the apparatus of  FIGS. 55 &amp; 56  may be used to maintain the submucosal space in the absence of, e.g., the gas, liquid, or other material used to create the submucosal space. 
     The depicted device includes a delivery sheath  1210  and a cage  1230 . The delivery sheath  1210  includes a lumen with an opening at a distal end of the delivery sheath  1210 . The delivery sheath  1210  defines a longitudinal axis extending between its distal end and a proximal end. The cage  1230  is operatively connected to an actuator that extends through the lumen to the proximal end of the delivery sheath  1210 . The actuator is preferably movable to advance the cage  1230  out of the lumen and retract the cage  1230  within the lumen. The cage  1230  can be advanced out of the lumen  1220  of the sheath  1210  such that the cage  1230  expands to, e.g., support tissue. 
     The cage  1230  includes struts  1232  that extend between a distal retainer  1234  and a proximal retainer  1236 . The proximal retainer  1236  may preferably be operated from a proximal end of the apparatus such that the sheath  1210  and the cage  1230  can be moved relative to each other in the proximal and distal directions. Movement such that the cage  1230  extends out of the lumen  1220  of the sheath  1210  may be accomplished using an actuator  1228  (the distal end of which is depicted in  FIG. 55 ). 
     The struts  1232  of the cage  1230  may preferably be in a restrained configuration when located within the lumen  1220  and an expanded configuration when advanced distally out of the lumen  1220  in the expanded configuration as depicted in  FIG. 55 , the struts  1232  preferably move radially outward from the longitudinal axis  1202  that extends along the length of the sheath  1210 . The struts  1232 , when deployed outside of the lumen  1220  may not fully expand if they are in an internal body location that constrains their expansion. The force applied by the struts  1232  on the surrounding tissue may, however, preferably force the tissue outward from the longitudinal axis  1202 . 
     Although the struts  1232  are depicted as expanding generally equally in all directions, it will be understood that they may preferentially expand on only one or more directions. In addition, although the struts  1232  are depicted as taking a generally bell-shape when expanded, it will be understood that they may take a variety of different shapes. 
     The expansion force used to expand the cage  1230  may preferably be supplied by the struts  1232  themselves which may preferably be constructed of materials that can be restrained within the lumen  1220  of sheath  1210  for delivery, but can then expand when released from the constraints of the lumen  1220 . It may further be preferred that the struts  1232  possess physical characteristics such as elasticity and resiliency that allow the cage  1230  to be retracted back into lumen  1220  after advancement out of the lumen  1220 . Retraction and advancement may preferably be used to control the size of the cage  1230  within, e.g., the submucosal space of a bleb or any other selected location (e.g., internal body lumens in the colon, gastro-intestinal system, blood vessels, urinary tract, etc.). 
     Examples of suitable materials for the struts  1232  of the cage  1230  may include, e.g., metals, polymers, shape memory metals, shape memory polymers, etc. The distal and proximal retainers  1234  and  1236  may be made of the same or different materials. 
     Another optional feature of the apparatus depicted in  FIGS. 55 &amp; 56  is that the cage  1230  may be designed to allow the passage of an apparatus  1240  into the volume of the expanded cage  1230 . The apparatus  1240  may be, e.g. an imaging device (e.g., colonoscope, etc.), resection device (for resecting tissue surrounding or extending into the cage  1230 ), etc. The apparatus  1240  may preferably be movable longitudinally within the delivery sheath  1210 , wherein the device  1240  can be advanced into the cage  1230  when the cage  1230  is in the expanded configuration. It may also be preferred that the apparatus  1240  be capable of retraction in the proximal direction such that the apparatus  1240  can be withdrawn back into the delivery sheath  1210 . 
     Although only one lumen is depicted in delivery sheath  1210 , it should be understood that multiple lumens could be provided to allow for independent advancement and retraction of the cage  1230  and apparatus  1240 . Further, although only one apparatus  1240  is depicted, it should be understood that more than one apparatus could be advanced into the cage  1230  at one time. 
     Still another variation of the apparatus is depicted in  FIG. 57  in which a cage  1330  is provided without a distal retainer such that as the sheath  1310  is withdrawn, the struts  1332  of the cage  1330  expand in the absence of distal retainer. Although a distal retainer such as that seen in  FIG. 55  is not included, the distal ends of the struts  1332  may still be connected to each other if so desired. Advancement of the sheath  1310  in the distal direction may preferably cause the cage  1320  to collapse such that the struts  1332  are again contained within the sheath  1310  (as described above in connection with, e.g., the embodiment of  FIGS. 55 &amp; 56 ). 
     Although not depicted, the apparatus of the present invention may use a variety of different actuating mechanisms to move the needles, resection frames, staples, jaws, cutting members, snares, etc. The actuators may be in the form of electromagnetic actuators, hydraulic actuators, pneumatic actuators, screw drives, push/pull rods extending the length of the elongated body for manual operation by a user, etc. Typically, the specific actuating mechanism(s) selected will be known to those of skill in the art of medical devices. In addition, the resection devices of the invention may preferably be mounted on elongated bodies for delivery to internal body locations, potentially through or on an endoscope. The materials used to construct the various resection devices may preferably be those materials suitable for use in medical devices, e.g., metals, polymers, composite materials, etc. 
     As used herein and in the appended claims, the singular forms “a,” “and,” and “the” include plural referents unless explicitly limited to the singular form or the context clearly dictates otherwise. 
     All references and publications cited herein are expressly incorporated herein by reference in their entirety into this disclosure. Illustrative embodiments of this invention are discussed and reference has been made to possible variations within the scope of this invention. These and other variations and modifications in the invention will be apparent to those skilled in the art without departing from the scope of the invention, and it should be understood that this invention is not limited to the illustrative embodiments set forth herein. Accordingly, the invention is to be limited only by the claims provided below and equivalents thereof.