Patent Publication Number: US-9833129-B2

Title: Endoluminal crawler

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/108,344 filed May 16, 2011, which claims benefit of and priority to U.S. Provisional Application No. 61/355,638 filed Jun. 17, 2010, and the disclosures of each of the above-identified applications are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates generally to an endoscopic apparatus and, more particularly, to a self-propelled endoluminal device that moves in a tubular organ. 
     Background of Related Art 
     A typical endoscope includes a flexible tube that is inserted through the gastrointestinal tract of a patient starting from the rectum or from the esophagus. The tip of the endoscope that is introduced in the gastrointestinal tract can be outfitted with several devices, most notably a light source and a camera, so that a user of the endoscope can observe the interior of the gastrointestinal tract and maneuver the endoscope to the proper position. 
     Once the endoscope is placed at the desired location in the gastrointestinal tract, surgical tools may be inserted through a working channel defined in the endoscope. As such, the surgical tools inserted in the endoscope will also easily reach the desired location. 
     The conventional method requires a highly skilled endoscopist to steer and push the endoscope through the gastrointestinal tract. However, even the highly skilled endoscopist oftentimes faces the difficulty of having to maneuver the long flexible tube through a narrow cavity, while steering the distal end of the flexible tube inside the body cavity. This can create an inherently unstable condition, which may result in excessive extension or dilation of the tubular organ. The excessive extension or dilation of the tubular organ causes pain and discomfort in patients, and can increase the risk of puncturing of the wall of the tubular organ which can cause infection or peritonitis. 
     SUMMARY 
     In accordance with one aspect of the present disclosure, there is provided a self-propelled endoluminal device including a body and an actuation unit disposed within the body. The body includes a tubular portion defining at least one slot. The actuation unit includes an actuator providing a rotational output and a traction belt including a traction portion and an engaging portion. The traction portion at least partially protrudes out of the slot and the engaging portion operatively engages the actuator. 
     Preferably, a tapered portion extends longitudinally from the tubular portion. The tapered body portion can include a flexible material configured to adapt to the shape of a tubular organ. 
     In some embodiments, a roller rotatably supports the traction belt in the body and the traction belt is continuously looped such that the rotational output of the actuator provides continuous rotation of the traction belt within the slot. 
     In some embodiments, the actuation unit may include a worm gear defining a longitudinal axis operatively coupled to the actuator and engaging the engaging portion of the traction belt. The continuously looped traction belt can extend along the length of the worm gear. The worm gear in some embodiments may define a working channel therein, and the working channel can extend along the length of the worm gear. In some embodiments, a distal end portion of the body may define an aperture in communication with the working channel. The aperture can be configured to receive surgical tools therethrough. 
     In some embodiments, the traction belt includes a plurality of substantially transverse grooves configured to engage teeth of a gear, e.g. a worm gear. Alternatively, the traction belt may include a plurality of ribs configured to engage teeth of a gear such as a worm gear. 
     In alternate embodiments, the actuation unit may include a pinion gear operatively coupled to the actuator and engaging the engaging portion of the traction belt such that the rotational output of the actuator rotates the continuously looped traction belt. 
     In some embodiments, the body may include a viewing window radially surrounding the aperture. The viewing window can be made of transparent material. 
     The device may further include an internal power source to supply power to the actuator providing the rotational output. The device may further include a light source. The light source can be powered by the internal power source. 
     In accordance with another aspect, the present disclosure provides an endoluminal device comprising a body and a traction member disposed within the body, the body having a slot formed therein to provide an opening for the traction member to contact an inner surface of a body lumen. The traction member has a traction surface engageable with the body lumen inner surface, the traction member being movable to advance the endoluminal device along the body lumen. 
     The traction member may include a traction belt maintained in a continuous loop movable in a direction along a longitudinal axis of the device. A gear mechanism can be provided for moving the traction belt. In some embodiments, the length of the belt can exceed the length of the slot. 
     In accordance with another aspect of the present disclosure, there is provided an endoscope including a housing, a flexible tube longitudinally extending from the housing, and an endoluminal device attached to the flexible tube. The endoluminal device includes a body and an actuation unit disposed within the body. The body includes a tubular portion defining at least one slot, preferably a longitudinal slot. The actuation unit includes an actuator providing a rotational output and a traction belt including a traction portion and an engaging portion. The traction portion partially protrudes out of the slot and the engaging portion operatively engages the actuator. 
     In some embodiments, a roller rotatably supports the traction belt in the body. The traction belt is preferably continuously looped such that the rotational output of the actuator provides continuous rotation of the traction belt at least partially within the at least one longitudinal slot. At least one roller can be provided to rotatably support the traction belt in the body. 
     In some embodiments, the housing defines an aperture in communication with the body to receive a surgical tool therethrough. The body can define an opening at a distal portion thereof in communication with the aperture for receiving therethrough the surgical tool. 
     In some embodiments, the actuation unit further includes a worm gear operatively coupled to the actuator and engaging the engaging portion of the traction belt. In some embodiments, the worm gear defines a working channel therein extending along a length of the worm gear. 
     In alternate embodiments, the actuation unit further includes at least one pinion gear, the at least one pinion gear being operatively engaged to the actuator and engaging the engaging portion of the traction belt such that the rotational output of the actuator rotates the continuously looped traction belt. 
     In some embodiments, the distal end portion of the body includes a viewing window, the viewing window radially surrounding the opening and further comprising a camera in the body adjacent the viewing window. 
     In some embodiments, the tapered portion of the body includes a flexible material, and is configured to adapt to the shape of a tubular member. The tapered portion can extend longitudinally from the tubular portion. 
     The endoluminal device can in some embodiments be releasably attached to the flexible tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and features of the present disclosure will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a prior art endoscope; 
         FIG. 2  is a cross-sectional view of a distal end of an insertion tube of the endoscope of  FIG. 1 ; 
         FIG. 3  is a perspective view of an endoluminal crawler in accordance with an embodiment of the present disclosure; 
         FIG. 4  is a top perspective view of an actuation unit of the endoluminal crawler of  FIG. 3 ; 
         FIG. 4A  is a cross-sectional view taken along lines  4 A- 4 A of  FIG. 3 ; 
         FIG. 4B  is a perspective view of an alternate embodiment of the endoluminal crawler; 
         FIG. 4C  is a top perspective view of an actuation unit of the endoluminal crawler of  FIG. 4B ; 
         FIG. 5  is a partial longitudinal cross-sectional view of a longitudinal slot defined in the endoluminal crawler of  FIG. 3 ; 
         FIG. 6  is perspective view of an endoluminal crawler in accordance with another embodiment of the present disclosure; 
         FIG. 7  is a perspective view of an actuation unit of the endoluminal crawler of  FIG. 6 ; 
         FIG. 8  is a perspective view of an endoluminal crawler in accordance with still another embodiment of the present disclosure; 
         FIG. 9  is a perspective view of endoluminal crawler in accordance with still another embodiment of the present disclosure; and 
         FIG. 10  is a perspective view of an endoluminal crawled mounted on an endoscope tube. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the presently disclosed endoluminal device will now be described in detail with reference to the drawings, wherein like reference numerals identify similar or identical elements. In the drawings and in the description that follows, the term “proximal,” will refer to the end of a device or system that is closer to the operator, while the term “distal” will refer to the end of the device or system that is further from the operator. 
     A prior art endoscope is illustrated in  FIG. 1  and is designated by reference numeral  10 . Endoscope  10  includes an endoscope housing  20  and a flexible insertion tube  30  extending distally from housing  20 . As best shown in  FIG. 2 , insertion tube  30  defines therein a viewing channel  32 , a light source channel  34 , a suction channel  36 , a tool channel  37 , and water/air supply channel  38 . 
     Viewing channel  32  may include a viewing window at a distal end thereof. A camera or fiber optic bundle is inserted through viewing channel  32  to capture images of a tubular organ through the viewing window. The captured images are transmitted to an operation unit  40  which transfers the images to an external display terminal (not shown) via a universal cord  42 . In addition, a light source (not shown) is provided through light source channel  34  to aid the user in viewing the surgical site and maneuvering distal section  30   a . Air or water may be supplied to the surgical site by a nozzle provided at a distal end of water/air supply channel  38 . A button  46  on operation unit  40  may be operated to turn on or off the air or water supply. The air or water supplied by the nozzle is suctioned through an opening provided at a distal end of suction channel  36 . The suction can be performed by an operation of a suction control button  48 . The fluid suctioned through opening  36  is discharged out of the patient&#39;s body. Tool channel  37  is in communication with insertion opening  44  defined in operation unit  40  such that upon positioning distal end  30   a  of insertion tube  30  at the surgical site of interest, surgical tools, e.g., forceps  50 , may be inserted through insertion opening  44  and be directed to the surgical site through tool channel  37 . A bending section  39  of flexible insertion tube  30  at the distal portion may be remotely manipulated in multi-directions through the use of control knob  52  on operation unit  40 . 
     Referring now to  FIGS. 3 and 4 , an embodiment of the present disclosure is shown generally as an endoluminal device  100 . Endoluminal device  100  is a crawler device which includes an outer body  150  and an actuation unit  120  positioned within outer body  150 . While the size of outer body  150  may be tailored to meet the specific needs of the procedure being performed, outer body  150  in most applications is dimensioned so that outer body  150  is large enough to accommodate actuation unit  120  therein, but small enough to fit within the smallest expected dimension of the tubular organ. Endoluminal crawler  100  may be employed as an independent module, or alternatively as an attachment to a conventional endoscope e.g., at a distal end portion of the insertion tube, to facilitate navigation of the insertion tube through a tubular organ. An example of endoluminal device mounted to an endoscope is shown in  FIG. 10 . As an independent module, surgical tools are attached to endoluminal crawler  100  which guides the surgical tools to a surgical site of interest to carry out, for example, removal of polyps, irrigation, and suction. A camera or illuminator can be attached to the front (distal) portion of the crawler for visualization as advanced. Endoluminal crawler  100  navigates through the labyrinth of the gastrointestinal tract or other body lumens with less difficulty, as compared to manual insertion of the flexible insertion tube  30  of the prior art endoscope  10  through the tubular organ. 
     Outer body  150  of endoluminal crawler  100  includes a generally tubular portion  156  and a tapered distal portion  158  with respect to a longitudinal axis “X-X” to facilitate navigation through the tubular organ. As such, body  150  has a streamlined torpedo-like shape. Tapered portion  158  distally extending from tubular portion  156  may be integrally formed with tubular portion  156 . Tapered portion  158  may alternatively be attached to tubular portion  156  and may include a flexible or resilient material for navigating through the tubular organs. A tapered portion, e.g. torpedo-like shape, can also be formed at the opposing end in each of the embodiments disclosed herein to facilitate movement in the reverse direction. Tubular portion  156  of outer body  150  defines a plurality of spaced apart longitudinal slots  154  in communication with an interior of body  150 . The longitudinal slots  154  are shown longitudinally aligned but alternatively one or more of the slots can be longitudinally offset. Slots  154  are preferably uniformly spaced around the radial perimeter of outer body  150 , though non-uniform spacing is also contemplated. Each longitudinal slot  154  accommodates a traction belt  142  of actuation unit  120  which partially protrudes through longitudinal slot  154  to provide traction against an interior wall of the tubular organ. Each traction belt  142  is preferably continuously looped, as will be discussed in greater detail below. Outer body  150  may be made of or coated with a material providing reduced friction with the interior wall of the tubular organ. 
     With particular reference to  FIG. 4 , actuation unit  120  is illustrated. Actuation unit  120  includes an actuation device  130 , e.g., a motor, a drive shaft  132 , a worm gear  134 , and a traction unit  140 . Actuation device  130  is operatively coupled to drive shaft  132  defining a longitudinal axis “Y-Y.” Worm gear  134  is mounted on drive shaft  132  such that when actuation device  130  rotates drive shaft  132 , worm gear  134  is concomitantly rotated therewith about longitudinal axis “Y-Y.” Drive shaft  132  is preferably concentrically mounted with body  150  such that rotation of worm gear  134  moves traction units  140   a ,  140   b  which are arranged around the radial perimeter of the interior wall of tubular portion  156 . Traction units  140   a ,  140   b  each include traction belt  142  and a set of rollers  144 . Only one unit, i.e. unit  140   a , is labeled in  FIG. 4  for clarity. Each traction belt  142  provides a continuous loop and is supported on the interior wall of body  150  by the set of rollers  144 . In particular, each roller  144  is rotatably supported by a support pin  145 . Ends of each support pin  145  are securely attached to an internal side of a respective side wall  159 , defining longitudinal slot  154  of body  150 , as best seen in  FIG. 5 . Alternatively, the support pin can be rotatable with roller  144 , and either a separate unit or formed integrally therewith. 
     At least one roller  144  is supported on the interior wall of body  150  adjacent a proximal portion of worm gear  134  and another roller  144  is supported on the interior wall of body  150  adjacent a distal end portion  136  of worm gear  134  such that traction belts  142  extend substantially along the length of worm gear  134 . The spacing of rollers  144  and the length of traction belts  142  are chosen to provide proper tension in traction belts  142  when rotated in a continuous loop. 
     Each traction belt  142  includes treads  146  defining a plurality of substantially transverse grooves  148 . The substantially transverse grooves  146  are illustratively uniformly arranged along the length of traction belt  142  and illustrated along a central region. The substantially transverse grooves  148  are configured to operatively engage and mesh with worm gear  134 . The grooves are preferably slightly offset from 90° angles with respect to the longitudinal axis of the unit  120  but can also be at other angles. Rotation of worm gear  134  about longitudinal axis “Y-Y” rotates continuously looped traction belt  142 . The continuously looped traction belt  142 , as viewed in the position of  FIGS. 4A and 4B , has an engaging portion  143   a  that engages worm gear  134  and a traction portion  143   b  protruding out of longitudinal slot  154  defined in outer body  150  and providing traction against the interior wall of the tubular organ. Because traction belt  142  is continuously looped, engaging portion  143   a  and traction portion  143   b  move in opposite directions when worm gear  134  rotates about longitudinal axis “Y-Y”, and upon sufficient looping movement, engaging portion  143   a  becomes the tissue traction portion and traction portion  143   b  becomes the gear engaging portion. Change in the direction of travel for endoluminal crawler  100  can be achieved by simply changing the direction of rotation of worm gear  134  and the drive shaft  132 . While traction belt  142  of  FIG. 4  has treads  146  adjacent the plurality of transverse grooves  148 , treads  146  may provide a plurality of protruding teeth configured to mesh with teeth provided on worm gear  134 , as in the treads  246  of the embodiment of  FIGS. 6 and 7  discussed in greater detail below. 
     With continued reference to  FIG. 4 , actuation unit  120  employs two traction units  140   a ,  140   b . A size or diameter of worm gear  134  may be varied to accommodate a greater number of traction units  140  that operatively engage worm gear  134  around the radial perimeter of worm gear  134 . The plurality of traction units  140  may enhance propulsion of endoluminal crawler  100  through the tubular organ by providing greater points of traction against the interior wall of the tubular organ. Even though the plurality of traction units  140  may require a larger worm gear  134 , e.g., one that has a diameter larger than a width of traction belt  142 , to accommodate a plurality of traction units  140  around the radial perimeter of worm gear  134 , it can be appreciated that by actuating the plurality of traction units  140  through a use of a single worm gear  134 , the overall size of endoluminal crawler  100  may be minimized. Moreover, it is further contemplated that each traction unit  140  may partially extend along the length of worm gear  134  such that a greater number of traction units  140  are accommodated on worm gear  134 . In particular, by placing traction units  140  offset from each other around the radial perimeter and along the longitudinal axis “Y-Y” of worm gear  134 , various non-uniform traction points against the interior wall of the tubular organ can be obtained. Such arrangement may provide enhanced traction against the interior wall of the tubular organ, as the tubular organ may not provide uniform contact against traction portions  143   b  while endoluminal crawler  100  travels through the tubular organ. 
     Protrusion of traction portion  143   b  out of longitudinal slot  154  ensures proper traction against the interior wall of the tubular organ. As a way of example, each roller  144  may be rotatably secured to a respective longitudinal side wall  159  defining longitudinal slot  154 , as shown in  FIG. 5 . Under such arrangement, an adequate amount of protrusion of traction portion  143   b  out of longitudinal slot  154  is achieved by dimensioning a height “H” of traction belt  142  wrapped around roller  144  to be greater than a thickness “T” of outer body  150  (i.e., outer diameter of body  150 -inner diameter of body  150 ). 
     Referring back to  FIG. 4 , worm gear  134  or shaft  132  may define a longitudinally extending working channel  137 . Working channel  137  can be utilized for passage of a camera, surgical tools and water. Working channel  137  may further be partitioned into several different channels to perform different functions as described. Such design may have a distal end portion  152  of outer body  150  that includes, for example; a viewing window for the camera and an aperture through which the surgical tools exit. In addition, distal end portion  152  of outer body  150  may further include an illumination device to aid the user in viewing the surgical site and maneuvering the endoluminal crawler  100 . 
     In the alternate embodiment of  FIGS. 4B and 4C , endoluminal device  400  has a body  450  with a tapered portion  458  extending from tubular portion  456 . Endoluminal device differs from device  100  of  FIG. 3  in that a portion of the traction belts are covered as described below. Slots  454   a ,  454   b  provide an opening for a respective traction belt  448   a ,  448   b . Actuation unit  420  is illustrated in  FIG. 4C . Endoluminal device  400  may be employed as an independent module or as an attachment to a conventional endoscopic apparatus. 
     Actuation unit  420  includes an actuation device  430 , e.g., a motor, a drive shaft  432 , a worm gear  434 , and a traction unit  440 . Actuation device  430  is operatively coupled to drive shaft  432  defining a longitudinal axis “Y-Y.” Worm gear  434  is mounted on drive shaft  432  such that when actuation device  430  rotates drive shaft  432 , worm gear  434  is concomitantly rotated therewith about longitudinal axis “Y-Y.” Drive shaft  432  is preferably concentrically mounted with body  450  such that rotation of worm gear  434  moves traction units  440   a ,  440   b  which are arranged around the radial perimeter of the interior wall of tubular portion  456 . Traction units  440   a ,  440   b  each include traction belt  442  and a set of rollers  444 . Each traction belt  442  provides a continuous loop and is supported on the interior wall of body  450  by the set of rollers  444 . In particular, each roller  444  is rotatably supported by a support pin  445 . Ends of each support pin  445  are securely attached to an internal side of a respective side wall as in the embodiment shown in  FIG. 5 . Alternatively, the support pin can be rotatable with roller  444 , and either a separate unit or formed integrally therewith. At least one roller  444  is supported on the interior wall of body  450  adjacent a proximal portion of worm gear  434  and another roller  444  is supported on the interior wall of body  450  adjacent a distal end portion  436  of worm gear  434  such that traction belts  442  extend substantially along the length of worm gear  434 . The spacing of rollers  444  and the length of traction belts  442  are chosen to provide proper tension in the traction belt  442  when rotated in a continuous loop. By covering a portion of the substantially transverse grooves  446  of the respective belt, i.e. by surface or wall  459  of body  450 , it reduces the chances of debris getting caught in the worm gear  434  as the tissue engaging portion loops a sufficient amount to contact the gear, while still providing sufficient engagement/traction with the organ for movement therein. The treads  442  on each side of the belt protrude through one of the slots  454   a . The treads  442  of traction portion  443   b  can be on a substantially planar surface similar to the  FIG. 4A  embodiment or can be radiused as shown in  FIG. 4C , with the raised edges along the longitudinal edges. This radius reduces sharp corners/edges to provide an even more atraumatic surface. The concavity or indentation along the central portion also can accommodate the covering wall  459  of the wall of the tubular portion. (The raised longitudinal edges are exposed through the slots  454   a ,  454   b  to provide traction). 
     With reference now to  FIGS. 6 and 7 , an endoluminal device  200  in accordance with another embodiment of the present disclosure is illustrated. Device  200  includes an endoluminal crawler having an outer body  250  defining a longitudinal axis “Z-Z” and an actuation unit  220  accommodated within outer body  250 . Endoluminal crawler  200  may be employed as an independent module or as an attachment to a conventional endoscopic apparatus. Outer body  250  is similar to outer body  150  of endoluminal crawler  100  of  FIGS. 3  and  4 . In particular, outer body  250  includes a tubular portion  256  and a tapered portion  258  to facilitate navigation through the tubular organ. Outer body  250  can have a streamlined torpedo-like shape as shown. Tubular portion  256  defines a pair of spaced apart opposing longitudinal slots  254 , preferably about 180° degrees apart. While tapered portion  258  may be integrally formed with tubular portion  256 , tapered portion  258  may alternatively be attached to tubular portion  256 . Tapered portion  256  may include a flexible or resilient material to adjustably navigate through the tubular organ. 
     Each longitudinal slot  254  accommodates a traction belt  242  which partially protrudes through longitudinal slot  254  to provide traction against the interior wall of the tubular organ. Each traction belt  242  is continuously looped and is selectively made of material that provides enhanced traction against the interior wall of the tubular organ. In contrast, outer body  250  can be made of or coated with a material providing a minimal amount of friction against the interior wall of tubular organ. 
     With reference now to  FIG. 7 , actuation unit  220  is illustrated. Actuation unit  220  includes a pair of pinion gears  234 ,  235  and a pair of traction units  240 . Pinion gears  234 ,  235  are engaged and meshed with each other such that pinion gears  234 ,  235  rotate in opposite directions “c,” “cc.” An actuation device, e.g., motor (not shown), may be operatively coupled to one of the pair of pinion gears  234 ,  245 . Each traction unit  240  includes a traction belt  242  and a set of rollers  244 . Traction belt  242  is continuously looped and is supported on an interior wall of body  250  by the set of rollers  244 . In particular, each roller  244  is rotatably supported by a support pin  245 . Ends of each support pin  245  are securely attached to longitudinal side walls  259  defining longitudinal slot  254 . Alternatively, as with the embodiment of  FIG. 4 , the pin and roller can rotate as a unit with the pin being a separate unit or integral. 
     The set of rollers  244  in each traction unit  240  are arranged along the longitudinal axis “Z-Z,” such that traction belts  242  extend substantially along the length of the tubular portion  256  of body  250 . The spacing of rollers  244  and the length of the traction belt  242  are chosen to provide proper tension in the traction belt  242 . The elasticity of the material used to make the traction belts  242  may also be considered in determining the proper tension of the traction belt  242 . 
     Each of the continuously looped traction belts  242  includes an engaging portion  243   a  that engages a respective pinion gear  234 ,  235  and a traction portion  243   b  that protrudes out of respective longitudinal slot  254  defined in outer body  250  and provides traction against the interior wall of the tubular organ. Because traction belt  242  is continuously looped, engaging portion  243   a  and traction portion  243   b  move in opposite directions when the actuation device rotates pinion gears  234 ,  235 . Thus, upon sufficient movement, the tissue engaging portion  243   b  becomes the gear engaging portion and the gear engaging portion  243   a  becomes the tissue engaging (traction) portion. The change in direction of travel for endoluminal crawler  200  can be achieved by simply changing the direction of rotation of pinion gears  234 ,  235  to move the traction belts  242  in the reverse direction. 
     Each traction belt  242  includes treads  246  having a plurality of protruding ribs  248 . The protruding ribs  248  are preferably uniformly arranged along the length of traction belt  242 . The protruding ribs  248  are configured to operatively engage and mesh with respective pinion gears  234 ,  235 . As such, rotation of pinion gears  234 ,  235  causes rotation of continuously looped traction belts  242 . The protruding ribs  248  may be integrally formed with traction belt  242 . Alternatively, each protruding rib  248  may be formed on a link and each link may be connected to form a continuously looped traction chain. While traction belt  242  has treads  246  including the plurality of protruding ribs  248 , traction belt  242  may define a plurality of substantially transverse grooves configured to mesh with teeth provided on pinion gears  234 ,  235 , as shown and described above in the previous embodiment. 
     It is also contemplated that a width of traction belt  242  is larger than that of longitudinal slot  254  and the plurality of protruding ribs  248  are dimensioned to fit within longitudinal slot  254 . As such, traction belt  242  is rotated within the interior wall of body  250  while the protruding ribs  248  protrude from traction belt  242  through longitudinal slot  254  and provide traction against the interior wall of the tubular organ, e.g. bowel or other part of the body. Such arrangement provides greater stability as traction belt  242  provides support against the interior wall of body  250 . It is further contemplated that additional rollers  244  may be provided to direct traction belt  242  away from proximal and distal edges  292 ,  294  of longitudinal slot  254  to prevent the plurality of protruding ribs  248  from interfering with proximal and distal edges  292 ,  294 . Moreover, longitudinal slot  254  is dimensioned to minimize respective gaps between traction belt  242  and proximal and distal edges  292 ,  294  of longitudinal slot  254 , to prevent pinching of the tubular organ. 
     The longitudinal slots  254 , in some embodiments, can be divided by a wall of the tubular body as in the embodiment of  FIG. 4B  to reduce debris. 
     With continued reference to  FIG. 7 , a single actuation unit  220  having two traction units  240  is illustrated. Endoluminal crawler  200 , however, may employ a plurality of actuation units  220  within body  250  to improve traction against the interior wall of tubular organ. In such a case, actuation units  220  are arranged in tandem along the length of body  250 . In order to provide uniform traction, actuation units  220  may be uniformly arranged around radial perimeter of body  250 . For example, a pair of actuation units  220  may be arranged such that traction portions  243   b  of traction unit  240  are orthogonal to each other. In any case, the number of actuation units  220  in body  250  may be chosen based on the surgical procedure being performed, as the type of surgical tool that must be carried by endoluminal crawler  200  determines how much traction force is required against the interior walls of tubular organ for propulsion of crawler  200 . 
     As in device  100  and  400 , a camera or illuminator can be attached to the (distal) portion of crawler  200  (or to the other crawler devices disclosed herein) for visualization as advanced. 
     In the alternate embodiment of  FIG. 9 , crawler  500  has an opening  552  in body  550  through which surgical instruments can be advanced; e.g. grasper G with movable jaws G 1 , G 2 . In this embodiment, the actuation unit can be similar to that of  FIG. 4 , with traction belts  542  extending through longitudinal slots  554 , and movable in a continuous loop by a worm gear (not shown) similar to gear  134  of  FIG. 4 . The worm gear drive shaft would have an opening extending longitudinally therethrough to accommodate the shaft A of grasper G. Jaws G 1 , G 2  would be advanced through the drive shaft opening in a closed position and remotely operable (e.g. opening/closing and articulation). 
     With reference to  FIG. 8 , an endoluminal device  300  in accordance with another embodiment of the present disclosure is illustrated. Endoluminal device  300  includes a crawler having an outer body  350  and an actuation unit (not shown) accommodated within outer body  350 . Any of the above described actuation units may be employed in endoluminal crawler  300  to move traction belt  342 . Moreover, endoluminal crawler  300  may be employed as an independent module or an attachment to a conventional endoscope, as described above. Outer body  350  of endoluminal crawler  300  has a generally tubular configuration with a tapered distal portion  352 . The non-tapered portion of outer body  350  defines a pair of opposing longitudinal slots  354 , preferably about 180° degrees apart although others spacings and additional slots to accommodate additional belts are contemplated. Each longitudinal slot  354  accommodates a continuously looped traction belt  342  which partially protrudes through longitudinal slot  354  to provide traction against the interior wall of the tubular organ. Traction belts  342  can be similar to belts  242  or  142  of the embodiments described above and driven in a similar fashion. Traction belts  342  can also be similar to belts  442  with body  350  and slots  354  similar to body  450  and slots  454   a ,  454   b  of  FIG. 4B . 
     Body  350  defines at a distal end portion thereof an aperture  356  and a viewing window  358  radially surrounding aperture  356 . Aperture  356  is in communication with an integral working channel that extends along the length of body  350 . The integral working channel is provided for the passage of the instruments and/or water into the tubular organ through aperture  356 . The channel in some embodiments can be formed in the drive shaft (not shown) which rotates the gears as in the embodiment of  FIG. 4C . Viewing window  358  is made of a transparent material so that a camera and light source provided within body  350  adjacent viewing window  358  may capture images of the surgical site through viewing window  358  and relay the images to an external display terminal for viewing by the user. Optionally, body  350  may provide a separate channel (e.g. built into the wall of body portion  350 ) for the camera and the light source to provide fluid tight environment for the camera and the light source. It is further contemplated that body  350  may further include a power supply to provide power to the actuation unit. 
     As noted above, endoluminal crawler  100 ,  200 ,  300 ,  400 ,  500  may be employed as an independent module as well as an attachment to a conventional endoscope. Operation of either type is substantially similar and will be described together in the interest of brevity. For brevity, only endoluminal crawler  100  will be described as the other crawlers described herein operate in a similar manner. In operation, crawler  100 , if separate, is first attached to a distal end portion of an insertion tube of a conventional endoscope. If endoluminal crawler  100  is an independent module it may attach thereto other surgical tools to guide the surgical tools to a surgical site of interest. Once the initial preparation has been performed, endoluminal crawler  100  is inserted through a tubular organ, at which time traction portions  143   b  of belts  142  are in contact with the interior walls of the tubular organ. Thereafter, a user powers on actuation device  130  of actuation unit  120  which in turn rotates worm gear  134 . Actuation can be achieved remotely or via electrical connections extending from the actuation unit  120  connected to an external power switch. Upon actuation, traction belts  142  engaging worm gear  134  rotate on a continuous loop. As such, traction portions  143   b  move in the direction of arrows “A” and “B” as shown in  FIG. 3 . Traction portions  143   b  of traction belts  142  propel endoluminal crawler  100  distally in the direction opposite of arrows “A,” “B.” Devices  200 ,  300 ,  400  and  500  would also operate by powering on their respective actuation devices to move their respective traction belts. 
     As endoluminal crawler  100  travels into the tubular organ, the insertion tube or surgical tools attached to endoluminal crawler  100  follows into the tubular organ. Once endoluminal crawler  100  is in position along the tubular organ, as determined by a user who views the images of the tubular organ on an external display terminal, the surgical tools attached to endoluminal crawler  100  or inserted through the endoscope can be placed at the proper surgical site. At this time, various procedure(s) including, e.g., removal of polyps, irrigation, suction, and/or biopsy, may be performed by the surgical tools passed through working channel  136 . Upon completion of the surgical procedure(s), endoluminal crawler may be removed by reversing the direction of rotation of actuation device  130  which in turn moves the traction portions  143   b  in the direction opposite of arrows “A,” “B,” thereby propelling crawler  100  in a proximal direction of arrows “A” and “B.” 
     Self-propelled endoluminal crawler  100  navigates through the tubular organ with ease as compared to the manual insertion of the tubular member of the endoscope. In addition, the self-propelled endoluminal crawler  100  reduces patient discomfort and trauma caused by excessive extension or dilation of the tubular member which can take place during manual insertion of the endoscope into the tubular member. 
     The traction belts of the crawler devices  100 ,  200 ,  300 ,  400  and  500  described herein can also be driven by a rotating shaft, powered by an external drive motor or device. The devices can also have a wire connection to an external power source. 
       FIG. 10  show crawler device  100 ′ mounted to flexible tube  630  of endoscope  610 . Crawler device  100 ′ is identical to device  100 , except for the mounting to the endoscope tube, and therefore identical parts to crawler  100  are labeled with “prime” designations, e.g. body  150 ′ and belt  142 ′. Endoscope  610  is identical to endoscope  10  except it includes the crawler device  100 ′. The identical parts to endoscope  10  are labeled in the “600” series and therefore for brevity are not discussed herein as the discussion of the components of endoscope  10  above are applicable to endoscope  610 . 
     It will be understood that various modifications may be made to the embodiments of the presently disclosed endoluminal crawler. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.