Patent Publication Number: US-2017360282-A1

Title: Catheter including a bendable portion

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 14/224,091, filed Mar. 25, 2014, which is a continuation application of U.S. patent application Ser. No. 13/343,029, filed Jan. 4, 2012, which is a continuation application of U.S. patent application Ser. No. 12/600,838, which is a U.S. National Phase Application under 35 U.S.C. 371 of PCT International Application No. PCT/IL2008/000687, which has an international filing date of May 20, 2008. 
     Reference is made to the following related applications, the disclosures of which are hereby incorporated by reference and priority of which is hereby claimed pursuant to 35 U.S.C. 37 CFR 1.78(a) (4) and (5)( i ): PCT Application No. PCT/IL2007/000600, filed May 17, 2007; U.S. Provisional Patent Application Ser. No. 60/924,578, filed May 21, 2007, entitled BALLOON CATHETER WITH UNIQUE GUIDEWIRE ASSEMBLY; U.S. Provisional Patent Application Ser. No. 61/064,707, filed Mar. 21, 2008, entitled EXTERNAL CHANNEL FOR ELONGATED MEDICAL INSTRUMENTS; and U.S. Provisional Patent Application Ser. No. 61/064,735, filed Mar. 24, 2008, entitled BALLOON ASSEMBLY FOR ENDOSCOPY. 
     Reference is also made to applicant&#39;s copending PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; and PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, the disclosures of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to catheters generally. 
     BACKGROUND OF THE INVENTION 
     The following patent publications are believed to represent the current state of the art: U.S. Pat. Nos. 7,169,105 and 7,056,284. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide an improved catheter. The term “catheter” is used to define a medical device including a hollow tube which may be passed into a body for investigation and/or treatment. 
     There is thus provided in accordance with a preferred embodiment of the present invention a catheter including a tube having at least one lumen, at least one elongate element, the at least one elongate element having a bendable portion at a predetermined bendable portion location therealong forward of a distal end of the tube and at least one selectably inflatable balloon communicating with at least one of the at least one lumen, the at least one selectably inflatable balloon having a forward end and a rearward end, the rearward end of the balloon being located rearwardly of the predetermined bendable portion location. 
     Preferably, the forward end of the balloon is located rearwardly of the predetermined bendable portion location. Alternatively, the forward end of the balloon is located forwardly of the predetermined bendable portion location. 
     In accordance with a preferred embodiment of the present invention the catheter also includes a steering element coupled to the elongate element forwardly of the predetermined bendable portion location. Additionally, the steering element is manipulatable by an operator for steering of the catheter. Additionally or alternatively, the steering element is operative to apply a pulling force to a distal portion of the elongate element. 
     Preferably, the pulling force causes the distal portion to rotate relative to a longitudinal axis of the catheter. Additionally, the at least one elongate element is resilient and returns to its axial orientation when the pulling force is no longer applied thereto. 
     In accordance with a preferred embodiment of the present invention a diameter of the balloon when fully inflated is in the range of 35-45 mm. 
     There is also provided in accordance with another preferred embodiment of the present invention a catheter including a tube having at least one lumen and having a bendable portion at a predetermined bendable portion location therealong and at least one selectably inflatable balloon communicating with at least one of the at least one lumen, the at least one selectably inflatable balloon having a forward end and a rearward end, the rearward end of the balloon being located rearwardly of the predetermined bendable portion location. 
     Preferably, the forward end of the balloon is located rearwardly of the predetermined bendable portion location. Alternatively, the forward end of the balloon is located forwardly of the predetermined bendable portion location. 
     In accordance with a preferred embodiment of the present invention the catheter also includes a steering element coupled to the tube forwardly of the predetermined bendable portion location. Additionally, the steering element is manipulatable by an operator for steering of the catheter. Additionally or alternatively, the steering element is operative to apply a pulling force to a distal portion of the tube. 
     Preferably, the pulling force causes the distal portion to rotate relative to a longitudinal axis of the catheter. Additionally, the tube is resilient and returns to its axial orientation when the pulling force is no longer applied thereto. 
     In accordance with a preferred embodiment of the present invention a diameter of the balloon when fully inflated is in the range of 35-45 mm. 
     There is further provided in accordance with yet another preferred embodiment of the present invention a catheter including a tube having at least one lumen, at least one elongate element, at least part of which is extendable forwardly of a distal end of the tube to a fixed orientation at which a distal end of the at least one elongate element extends beyond the distal end of the tube by a fixed amount and at least one selectably inflatable balloon communicating with at least one of the at least one lumen, the at least one selectably inflatable balloon having a forward end and a rearward end, the rearward end of the balloon being located adjacent the distal end of the tube at a rearward balloon end mounting location and the forward end of the balloon being located adjacent a distal end of the at least one elongate element at a forward balloon end mounting location, wherein the balloon is configured such that when the at least one elongate element is in the fixed orientation and the balloon is in a deflated operative orientation, the distance between the rearward balloon end mounting location and the forward balloon end mounting location is greater than the distance between the rearward balloon end mounting location and the forward balloon end mounting location when the balloon is an inflated operative orientation, thereby producing bowing of the at least one elongate element upon inflation of the balloon. 
     Preferably, the distance between the rearward balloon end mounting location and the forward balloon end mounting location is greater than the distance between the rearward balloon end mounting location and the forward balloon end mounting location when the balloon is an inflated operative orientation by at least 20%. Additionally or alternatively, the bowing of the elongate element is in a predetermined direction. Alternatively or additionally, the bowing of the elongate element produces an asymmetric, inflated balloon configuration. 
     There is even further provided in accordance with still another preferred embodiment of the present invention a catheter including a tube having at least one lumen and at least one selectably inflatable asymmetrical balloon communicating with at least one of the at least one lumen, the at least one selectably inflatable asymmetrical balloon having a forward end and a rearward end, the balloon, when not inflated, having a generally tapered forward facing portion having increasing diameter from the forward end toward the rearward end and a generally tapered rearward facing portion having decreasing diameter from the forward end toward the rearward end, the extent of tapering of the forward and rearward facing portions being different. 
     Preferably, the extent of tapering of the forward portion is less than the extent of tapering of the rearward portion. 
     There is also provided in accordance with another preferred embodiment of the present invention an endoscope system including an endoscope, an external tube associated with the endoscope and extending alongside the endoscope; an endoscope tool extending through the external tube and having formed along at least part of an elongate surface thereof a hydrophilic coating and a liquid communication port associated with the external tube for providing liquid communication with the interior of the external tube. 
     There is further provided in accordance with yet another preferred embodiment of the present invention for use with an endoscope, an external tube assembly including an external tube associated with the endoscope and extending alongside the endo scope, an endoscope tool extending through the external tube and having formed along at least part of an elongate surface thereof a hydrophilic coating and a liquid communication port associated with the external tube for providing liquid communication with the interior of the external tube. 
     There is even further provided in accordance with still another preferred embodiment of the present invention an endoscope system including an endoscope, an external tube associated with the endoscope and extending alongside the endoscope and a drainage vessel associated with the external tube for receiving liquid from the interior of the external tube. 
     There is also further provided in accordance with a further preferred embodiment of the present invention for use with an endoscope, an external tube assembly including an external tube associated with the endoscope and extending alongside the endoscope and a drainage vessel associated with the external tube for receiving liquid from the interior of the external tube. 
     There is further provided in accordance with another preferred embodiment of the present invention an enhanced flexibility auxiliary endoscope assembly for use with an endoscope, the assembly including at least one flexible elongate element, a flexible sleeve having a first lumen for accommodating a distal portion of an endoscope and a second lumen for accommodating the at least one flexible elongate element and an inflatable balloon mounted onto the flexible sleeve, the inflatable balloon, when in a non-inflated state, having a forwardly facing generally tapered end and a rearwardly facing generally tapered end, the forwardly facing generally tapered end having a slope which is less steep than a corresponding slope of the rearwardly facing generally tapered end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
         FIGS. 1A and 1B  are, respectively, pictorial and exploded view simplified illustrations of a flexible endoscope system constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 2A and 2B  are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool and associated inflation tube, constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 3A and 3B  are sectional illustrations of the catheter or endoscope tool of  FIGS. 2A &amp; 2B  in respective straight and bent operative steering orientations; 
         FIGS. 4A and 4B  are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool and associated inflation tube, constructed and operative in accordance with another preferred embodiment of the present invention; 
         FIGS. 5A and 5B  are sectional illustrations of the catheter or endoscope tool of  FIGS. 4A &amp; 4B  in respective straight and bent operative steering orientations; 
         FIGS. 6A, 6B and 6C  are simplified schematic illustrations of an inflation control unit forming part of the flexible endoscope system of  FIGS. 1A and 1B  in three different operative orientations; 
         FIGS. 7A, 7B, 7C and 7D  are simplified flow charts illustrating preferred modes of operation of the inflation control unit of  FIGS. 6A-6C ; 
         FIGS. 8A and 8B  are simplified partially cut away illustrations of a balloon catheter constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 9A, 9B, 9C, 9D, 9E and 9F  are simplified, partially cut away, partially sectional, illustrations of the operation of the apparatus of  FIGS. 8A and 8B ; 
         FIGS. 10A and 10B  are simplified, partially cut away, partially sectional, illustrations of a balloon catheter/external tube assembly constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIGS. 11A, 11B, 11C, 11D, 11E &amp; 11F  are simplified, partially cut away, partially sectional, illustrations of the operation of the apparatus of  FIGS. 10A and 10B ; 
         FIG. 12  is a simplified illustration of a flexible endoscope system similar to that shown in  FIGS. 1A and 1B ; 
         FIGS. 13A and 13B  are simplified partially cut away illustrations of portions of the system of  FIG. 12 ; 
         FIGS. 14A, 14B, 14C &amp; 14D  are simplified, partially cut away, partially sectional, illustrations of the operation of an endoscope tool as shown and described hereinabove with reference to  FIGS. 2A-3B , including a balloon catheter as shown and described hereinabove with reference to  FIGS. 8A &amp; 8B , together with an endoscope, such as that shown and described hereinabove with reference to  FIGS. 9B-9F ; 
         FIGS. 15A and 15B  are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool and associated inflation tube, constructed and operative in accordance with another preferred embodiment of the present invention; 
         FIGS. 16A and 16B  are sectional illustrations of the catheter or endoscope tool of  FIGS. 15A &amp; 15B  in respective straight and bent operative steering orientations; and 
         FIGS. 17A and 17B  are simplified illustrations of a portion of an alternative embodiment of the flexible endoscope system of  FIGS. 1A and 1B . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The terms “endoscope” and “endoscopy” are used throughout in a manner somewhat broader than their customary meaning and refer to apparatus and methods which operate within body cavities, passageways and the like, such as, for example, the small intestine, the large intestine, arteries and veins. Although these terms normally refer to visual inspection, as used herein they are not limited to applications which employ visual inspection and refer as well to apparatus, systems and methods which need not necessarily involve visual inspection. 
     The team “distal” refers to the remote end of an endoscope, accessory or tool furthest from the operator. 
     The term “proximal” refers to the end portion of an endoscope, accessory or tool closest to the operator, typically outside an organ or body portion of interest. Reference is now made to  FIGS. 1A &amp; 1B , which illustrate an endoscopy system  100  constructed and operative in accordance with a preferred embodiment of the present invention. The endoscopy system  100  preferably includes a console  102 , such as a console including a EPK-1000 video processor and a SONY LMD-2140MD medical grade flat panel LCD monitor, all commercially available from Pentx Europe GmbH, 104 Julius-Vosseler St., 22527 Hamburg, Germany. The system  100  preferably includes a conventional flexible endoscope  104 , such as a VSB-3430K video enteroscope or a EC-3470LK video colonoscope which are commercially available from Pentx Europe GmbH, 104 Julius-Vosseler St., 22527 Hamburg, Germany. 
     In accordance with a preferred embodiment of the invention, an auxiliary endoscopy assembly  106  comprising a peripheral balloon  108  may be mounted onto endoscope  104  as shown, by means of a tubular sleeve  110  having a central lumen  111  which is placed over part of the distal portion of endoscope  104 , and is associated with peripheral balloon  108 . Many of the features of auxiliary endoscopy assembly  106  are described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It is appreciated that the tubular sleeve  110  may be constructed of a flexible and stretchable material, such as flexible and stretchable silicon, latex or rubber, thereby enabling it to conform with bending of endoscope  104 . It is further appreciated that tubular sleeve  110  preferably has an untensioned inner circumference slightly larger than the cross-sectional circumference of endoscope  104 , thereby allowing it to be pulled and slid over the endoscope  104 . 
     As illustrated in  FIGS. 1A &amp; 1B , peripheral balloon  108  at least partially overlays tubular sleeve  110  at a location adjacent a distal end of tubular sleeve  110 , and is fixed thereon at both edges by any suitable conventional means, such as an adhesive, in order to define a sealed volume therebetween. Preferably, inflation and deflation of peripheral balloon  108  is provided via a lumen  112 , which preferably is defined by tubular sleeve  110  and communicates with the interior of peripheral balloon  108  via at least one aperture  114 . Lumen  112  preferably communicates with an inflation control assembly  115  via a tube  116 . Inflation control assembly  115  preferably comprises a control unit  117  having associated therewith dual foot pedals  118  and an operational status indicator panel  119 . 
     Tube  116  may be attached to endoscope  104  at multiple locations along its length by any suitable conventional means such as medical adhesive tape or flexible bands  120 . 
     It is appreciated that in accordance with a preferred embodiment of the present invention peripheral balloon  108  is generally inflatable, and can be inflated to a diameter about 3-10 times larger than its diameter when not inflated. In accordance with a preferred embodiment of the present invention, useful for small intestine endoscopy, the diameter of peripheral balloon  108  when fully inflated is in the range of 35-45 mm. Preferably, inflation of the peripheral balloon  108  to a diameter less than 45 mm may be achieved using relatively low pressure, such as in the range of 30-70 millibars. 
     In another specific embodiment, useful for large intestine endoscopy, the diameter of the peripheral balloon, when fully inflated, is in the range of 4-6 centimeters. In a further embodiment, also useful for large intestine endoscopy, the diameter of the peripheral balloon, when fully inflated, is six centimeters. Preferably, inflation of the peripheral balloon  108  to a diameter less than six centimeters may be achieved using relatively low pressure, such as in the range of 30-70 millibars. 
     It is appreciated that in accordance with a preferred embodiment of the present invention, useful for in vivo inspection of a generally tubular body portion having a variable cross-sectional diameter, the expansion diameter range of peripheral balloon  108  is larger than the maximum cross-sectional diameter of the generally tubular body portion, thereby enabling engagement of expanded peripheral balloon  108  with the interior surface of the generally tubular body portion, and anchoring of the endoscope  104  thereto. Preferably, peripheral balloon  108  is a relatively soft, highly compliant balloon, operative to at least partially conform to the shape of the interior surface of the generally tubular body portion when in engagement therewith. 
     It is appreciated that peripheral balloon  108  may be formed of suitable well-known stretchable materials such as latex, flexible silicon, or highly flexible nylon. Alternatively, peripheral balloon  108  may be formed of polyurethane, which is less stretchable and conforming than latex, flexible silicon or highly flexible nylon. Preferably, the diameter of peripheral balloon  108  is sufficient to ensure tight anchoring at any part of the generally tubular body portion. Alternatively, peripheral balloon  108  may be obviated. 
     In accordance with one embodiment of the present invention, tubular sleeve  110  and peripheral balloon  108  may be produced from different materials. For example, sleeve  110  may be formed of very thin and very flexible polyurethane while balloon  108  is formed of nylon. Alternatively, sleeve  110  and balloon  108  may be produced from generally the same material but with different mechanical properties. For example, balloon  108  may be formed of a silicon material having width of 0.5 millimeter and hardness of approximately 50 shore D, whereas sleeve  110  may be formed of a silicone material having width of 0.3 millimeter and hardness of approximately 30 shore D. A preferred structure of sleeve  110  provides high bendability of the distal portion of endoscope  104  together with tubular sleeve  110 . A preferred structure of balloon  108  provides firm anchoring of endoscope  104  to the generally tubular body portion when balloon  108  is in an inflated state. 
     In a preferred embodiment of the present invention, auxiliary assembly  106  may comprise at least one external tube  122 . External tube  122 ′ may be attached to the endoscope  104  at multiple locations along its length by any suitable conventional means such as medical adhesive tape or flexible bands  120 . External tube  122  is preferably attached to tube  116  by a band  123 . A proximal end  124  of tube  122  is typically open to enable a proximal end  125  of an inflation tube  126  coupled to a balloon  127  of an endoscope tool  128  to extend therefrom outside of a patient&#39;s body, thereby enabling insertion, removal and manipulation of tool  128  by an operator. Additionally any other suitable endoscope tool may be inserted, removed or manipulated through tube  122 . Proximal end  125  of inflation tube  126  of endoscope tool  128  is also coupled to the inflation control assembly  115 . 
     Many of the features of endoscope tool  128  are described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     In accordance with a preferred embodiment of the present invention, useful for small intestine endoscopy, the diameter of balloon  127  when fully inflated is in the range of 35-45 mm. Preferably, inflation of the peripheral balloon  127  to a diameter less than 45 mm may be achieved using relatively low pressure, such as in the range of 30-70 millibars. 
     A distal end  129  of external tube  122  preferably extends slidably and telescopically through part of the length of a coil spring  130  which movably and slidably resides within a lumen  132 , which preferably forms part of tubular sleeve  110 . Preferably distal end  129  is beveled for ease of passage into and through coil spring  130 . It is a particular feature of the present invention that spring  130  defines a generally non-collapsible and highly flexible channel for endoscope tool  128 . It is a further particular feature of the present invention that lumen  132  has a generally saddle shaped cross section, as seen particularly at reference numeral  134 , which is sufficiently wide to enable spring  130  to be slidably displaced laterally depending on the curvature of the endoscope  104 . This enhances the flexibility of the combination of endoscope  104  and the auxiliary assembly  106 . It is appreciated that although provision of spring  130  is preferred, spring  130  may be replaced by a suitable, flexible, non-collapsible tube of another type. In accordance with a preferred embodiment of the present invention, useful for small intestine endoscopy, the inner diameter of spring  130  is in the range of 3-6 mm. Preferably, balloon  127  when in a fully deflated state may assume a small enough cross section to allow its positioning at least partially within spring  130  if needed, for example during oral insertion of the flexible endoscope assembly through the stomach into the small intestine. 
     As illustrated in  FIG. 1A , a distal end  136  of spring  130  is located adjacent to a first side wall  137  of lumen  132 . Spring  130  extends generally diagonally along lumen  132  such that a proximal end  138  thereof lies adjacent a second side wall  139  of lumen  132 , opposite to first side wall  137 . 
     It is appreciated that during operation of the endoscopy system  100 , when the endoscope  104  and the auxiliary endoscopy assembly  106  are curved in various directions, the orientation of spring  130 , particularly proximal end  138  thereof, may change appropriately. 
     It is seen that spring  130  is preferably angularly misaligned with a respect to the central lumen  111 . Generally diagonal orientation of spring  130  within lumen  132  is particularly useful in reducing, minimizing or eliminating substantial resistance of spring  130  to bending of endoscope  104  inserted within central lumen  111 . 
     A forward collar element  140  preferably receives distal end  136  of coil spring  130  and removably connects it to a distal end  142  of tubular sleeve  110  and thus to a distal end  144  of endoscope  104  in press-fit frictional engagement. A stretchable band  146  preferably surrounds collar element  140  and presses it into frictional engagement with distal end  142  of tubular sleeve  110  and with distal end  144  of endoscope  104 . It is appreciated that lumens  112  and  132  do not extend to distal end  142  of tubular sleeve  110  and thus are not engaged by collar element  140 . 
     It is appreciated that the lumens  111 ,  112  and  132  may be formed integrally as part of tubular sleeve  110  in any appropriate manner, such as by extrusion, for example. Alternatively, any one or more of lumens  111 ,  112  and  132  may be formed as a separate tube and may be attached to tubular sleeve  110  in any suitable manner, such as by an adhesive. 
     In a preferred embodiment of the present invention, tubular sleeve  110  is approximately 120-200 mm in length and spring  130  is approximately 100-160 mm in length. 
     Preferably, the longitudinal distance between a distal edge of peripheral balloon  108  and the distal edge of tubular sleeve  110  does not exceed approximately 20 mm. 
     It is a particular feature of the present invention that a typical wall thickness of lumens  111 ,  112  and  132  of the tubular sleeve  110  is relatively thin, such as in the range of 0.15-0.7 mm, so as to provide enhanced flexibility of the tubular sleeve  110 . 
     Preferably, for a typical endoscope diameter range of 10-13 mm, the circumference of central lumen  111  is preferably in the range of 31-41 mm, and its inner diameter is preferably 1-3 mm larger than the outer diameter of the endoscope. 
     In accordance with a preferred embodiment of the invention, inflation tube  126  includes a guide wire  150 , which is preferably selectably bendable at one or more predetermined bending locations, here indicated in phantom lines by indentations  152 . Guide wire  150  preferably terminates adjacent a distal end of balloon  127 . Further in accordance with a preferred embodiment of the present invention, inflation tube  126  also includes a selectable steering wire  154 , which extends beyond the proximal end of inflation tube  126 , so as to be manipulatable by an operator for steering of the endoscope tool  128 . 
     A distal end of selectable steering wire  154  is fixedly coupled to the guide wire  150  at an attachment location forwardly of one or more predetermined bending locations. The attachment location may be either interior of balloon  127  or forward thereof. Pulling on the selectable steering wire  154  causes bending of the guide wire  150  and corresponding steering of the endoscope tool  128 . 
     It is appreciated that the structure of the inflation tube  126 , including guide wire  150  and selectable steering wire  154 , and the corresponding structure of the endoscope tool  128 , although illustrated and described herein as an endoscope tool structure, is equally applicable to catheters generally, which may be employed without an endoscope. 
     Reference is now made to  FIGS. 2A and 2B , which are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool  128  and associated inflation tube  126  constructed and operative in accordance with a preferred embodiment of the present invention. As seen in  FIGS. 2A &amp; 2B , the inflation tube  126  terminates at a cap  156 , which is attached at the interior of a distal end of inflation tube  126  and preferably includes at least two lumens, here designated by reference numerals  158  and  160 . The guide wire  150  preferably extends through lumen  158  and is fixed to cap  156  thereat, while the selectable steering wire  154  preferably extends through lumen  160 . 
     A collar  166  preferably fixedly attaches a distal end of selectable steering wire  154  to the guide wire  150  forwardly of at least one indentation  152 . In this embodiment, the attachment location, designated by reference numeral  168 , of the distal end of the selectable steering wire  154  to the guide wire  150  by collar  166  lies within balloon  127 . 
     A distal end of the guide wire  150  preferably is fixed to a tip element  170 , preferably within a recess  172  formed therein. Balloon  127  is sealingly fixed, at a proximal end thereof, onto a distal end of inflation tube  126  and, at a distal end thereof, onto a proximal end of tip  170 . 
     Reference is now made to  FIGS. 3A &amp; 3B , which are sectional illustrations of the catheter or endoscope tool of  FIGS. 2A &amp; 2B  in respective straight and bent operative steering orientations.  FIG. 3A  shows the catheter or endoscope tool extending along a longitudinal axis  174 . It is seen that when selectable steering wire  154  is retracted relative to cap  156 , as indicated by arrow  176 , it applies a pulling force to a distal portion  178  to the guide wire  150  forward of indentation  152 , causing distal portion  178  and tip element  170  to rotate in a direction indicated by arrow  180  relative to longitudinal axis  174 . Preferably the guide wire  150  is sufficiently resilient under such bending so as to return to its axial orientation shown in  FIG. 3A  once selectable steering wire  154  is released. 
     It is appreciated that torque may be applied to tube  126  and/or guide wire  150 , thereby allowing an operator to rotate balloon  127  with tip element  170  around axis  174  during in vivo inspection of a tubular body portion, such as described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     Reference is now made to  FIGS. 4A and 4B , which are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool  128  and associated inflation tube  126  constructed and operative in accordance with another preferred embodiment of the present invention. As seen in  FIGS. 4A &amp; 4B , the inflation tube  126  terminates at a cap  186 , which is attached at the interior of a distal end of inflation tube  126  and preferably includes at least two lumens, here designated by reference numerals  188  and  190 . The guide wire  150  preferably extends through lumen  188  and is fixed to cap  186  thereat, while the selectable steering wire  154  preferably extends through lumen  190 . 
     A distal end  192  of selectable steering wire  154  is attached to a distal end  194  of guide wire  150  forwardly of at least one indentation  196 , which here is located forwardly of balloon  127  in a recess  198  formed in a tip element  200 . In this embodiment, the attachment of the distal end  192  of selectable steering wire  154  to the distal end  194  of guide wire  150  is realized by fixedly attaching distal ends  192  and  194  to the tip element  200 , within respective recesses  202  and  204 , and the attachment location, designated by reference numeral  206 , lies within tip element  200 . Balloon  127  is sealingly fixed, at a proximal end thereof, onto a distal end of inflation tube  126  and, at a distal end thereof, onto a proximal end of tip  200 . 
     Reference is now made to  FIGS. 5A &amp; 5B , which are sectional illustrations of the catheter or endoscope tool of  FIGS. 4A &amp; 4B  in respective straight and bent operative steering orientations.  FIG. 5A  shows the catheter or endoscope tool extending along a longitudinal axis  210 . As seen in  FIG. 5B , when selectable steering wire  154  is retracted relative to cap  186 , as indicated by arrow  212 , it applies a pulling force to distal end  194  of the guide wire  150  forward of indentation  196 , causing distal portion  194  and tip element  200  to rotate in a direction, indicated by arrow  214 , relative to longitudinal axis  210 . Preferably, the guide wire  150  is sufficiently resilient under such bending so as to return to its axial orientation shown in  FIG. 5A  once selectable steering wire  154  is released. 
     It is appreciated that torque may be applied to tube  126  and/or guide wire  150 , thereby allowing an operator to rotate balloon  127  with tip element  200  around axis  210  during in vivo inspection of a tubular body portion, such as described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     Reference is now made to  FIGS. 6A, 6B and 6C , which are simplified schematic illustrations of control unit  117  of inflation control assembly  115  of the flexible endoscope system of  FIGS. 1A and 1B  in three different operative orientations. 
     In a preferred embodiment of the present invention, the inflation control assembly  115  is constructed and operative to facilitate the pneumatic inflation and/or deflation of balloons  108  and  127 , which are coupled thereto by respective tubes  116  and  126 . 
     Control unit  117  of inflation control assembly  115  is preferably an electro-mechanically operative pneumatic control subassembly which includes on its front panel a power on/off switch  312 , connectors  313  and  314 , for respective tubes  116  and  126 , preferably female-type pneumatic connectors, and a buzzer mute switch  316 . 
       FIGS. 6A-6C  each also illustrate a foot pedal electrical connector  318 , an indicator panel electrical connector  320 , and a power supply electrical connector  322 , all of which are preferably female-type electrical connectors. 
     Specific reference is now made to  FIG. 6A , which is a simplified schematic illustration of the control unit  117  in an ambient inflation pressure operational state. As seen in  FIG. 6A , the control unit  117  includes, in addition to the various connectors and switches described hereinabove, an electronic controller  323 , a buzzer  324 , and two identical inflator/deflator assemblies, respectively indicated by reference numerals  326  and  328 . The electronic controller  323  is an electronic circuit which includes software that receives inputs from various components of the inflation control assembly  115  and activates various components of the inflation control assembly  115  in a manner which is described hereinbelow with reference to  FIGS. 7A-7D . 
     Inflator/deflator assemblies  326  and  328  each include a variable volume air reservoir  334  which is coupled in a closed circuit with a corresponding balloon  108  or  127  via a corresponding tube  116  or  126 . A piston  336  is movable within each air reservoir  334  to thereby vary the air volume  337  of the air reservoir  334 . Associated with each piston  336  is a flange  338  arranged such that, during the axial movement of piston  336 , flange  338  may be located adjacent a deflated balloon status sensor  340 , an ambient balloon status sensor  342  and an inflated balloon status sensor  344 . Each of sensors  340 ,  342  and  344  detects the proximity of flange  338  and provides a corresponding output to controller  323 , indicating the corresponding volume of the air volume  337  and thus the inflation/deflation status of a corresponding balloon. Sensors  340 ,  342  and  344  may be any suitable type of proximity sensors, such as optical sensors or capacitive sensors. An example of an appropriate sensor type is EE-SX672R, manufactured by Omron of Japan. 
     Piston  336  is driven linearly by a motor  346  moved inwardly or outwardly of air reservoir  334 , thereby respectively decreasing or increasing the air volume  337 . The operation of motor  346  is controlled by controller  323 . Motor  346  may be any suitable electric motor, such as a linear motor, a rotary motor or a step motor. 
     A mechanical stop  348  prevents the movement of piston  336  beyond a predefined distance, by physically engaging flange  338 . This limitation provides a limit on the pressure within air reservoir  334 , due to the limited decrease of the air volume  337  in air reservoir  334 . 
     Air reservoir  334  is pneumatically connected, via a first intermediate air tube  350 , to a valve  352  that has two states. An example of a suitable purging valve  352  is a solenoid valve G80-24V/DC 6.5 W TWO WAY NO 1.6 mm, manufactured by Baccara of Israel. When the valve  352  is a first state, it allows air flow via first intermediate air tube  350  between air reservoir  334  and the ambient atmosphere. When  352  is in a second state, air flowing via the first intermediate air tube  350  communicates via valve  352 , a balloon valve  354 , and a second intermediate air tube  356  with a corresponding balloon  108  or  127  ( FIGS. 1A &amp; 1B ). 
     Balloon valve  354  is typically a solenoid valve G80-24V/DC 6.5 W TWO WAY NO 1.6 mm, manufactured by Baccara of Israel. Balloon valve  354  may be in either one of two states; an open state and a closed state. When the balloon valve  354  is in the open state, air flowing in second intermediate air tube  356  can pass via the balloon valve  354  to a third intermediate air tube  358 . When balloon valve  354  is open, third intermediate air tube  358  couples air from second intermediate air tube  356  via balloon valve  354  to a pressure sensor  360 . 
     Pressure sensor  360  detects the air pressure in the third intermediate air tube  358 . The output of pressure sensor  360  may be used by controller  323  to govern the operation of the valve  352  and of the balloon valve  354 . An example of pressure sensor  360  is sensor number  6763 , manufactured by Hegra Electric Ltd, Northern Way, Bury St. Edmunds, Suffolk IP32 6NN, United Kingdom. 
     It is appreciated that the output of pressure sensor  360  may be employed by the controller  323  for actuation of balloon valve  354 , valve  352  and piston  336 . It is appreciated that actuation of the above described pneumatic components may be different for different levels of pressure or vacuum which are indicated by pressure sensor  360 . It is appreciated that pressure sensor  360  may comprise multiple pressure sensors, each of which may provide a digital input of a single pressure value. For instance, detection of pressure higher than 60 mbar by pressure sensor  360  may cause balloon valve  354  to be in its closed state. Detection of pressure that is below 60 mbar by the pressure sensor  360  may cause balloon valve  354  to be in its open state. Similarly, detection of a vacuum level lower than −100 mbar by pressure sensor  360  may cause the balloon valve  354  to be in its closed state. 
     A fourth intermediate air tube  362  allows air flow from air tube  358  via pressure sensor  360  to an overpressure release valve  364 . Release valve  364  has two states, an open and a closed state. In the closed state, release valve  364  allows air flow from fourth intermediate air tube  362  to a fifth intermediate air tube  366 . In the open state, release valve  364  directs the air flow from fourth intermediate air tube  362  to the ambient atmosphere. Release valve  364  is in its closed state as long as the pressure within air tube  362  is below a predefined value. Whenever the pressure in air tube  362  exceeds the predefined value, the release valve  364  is automatically shifted to its open state. 
     This ensures that the pressure in a fifth intermediate air tube  366  and any components connected thereto outside of the control unit  117  ( FIG. 1A ), does not exceed the predefined pressure value set for release valve  364 , corresponding to a safe, predefined value, such as 120 mbar. The transition of the release valve  364  from its closed to its open state may be automatic as in release valve 559B-1M-1.0 psi, manufactured by Circle Seal Controls, Inc., 2301 Wardlow Circle, Corona, Calif. 92880, USA. 
     It is appreciated that the release valve  364  may also be controlled by a backup control mechanism. 
     Each intermediate air tube  366  is connected to a corresponding one of tubes  116  and  126  ( FIG. 1A ) via a corresponding one of connectors  313  and  314 . 
     It is appreciated that inflator/deflator assemblies  326  and  328  can be operated using identical components and by implementing the same or different algorithms, such that, for example balloon  108  may operate at a maximum inflation of 60 mbar, while balloon  127  may operate at a maximum inflation of 90 mbar. 
     Reference is now made additionally to  FIGS. 7A-7D , which are simplified flow charts illustrating preferred modes of operation of the inflation control assembly  115  of  FIGS. 6A-6C . An indicated above, control of the operation of inflation control assembly  115  is provided principally by controller  323  based on various sensor inputs, described hereinabove. 
     It is appreciated that the implementation of controller  323  may involve any suitable technology, for example, the use of embedded firmware, loading software from a digital memory device and loading software from an external source. 
       FIGS. 7A and 7B  illustrate initialization functionality which is performed automatically once the power switch  312  is switched to its on state. A primary purpose of the initialization functionality is to ensure that, whatever is the initial state of the control unit  117  ( FIG. 1A ), prior to operation, balloons  108  and  127  are in their fully deflated (vacuum) operational states. 
     As seen in  FIGS. 7A and 7B , following powering on of the inflation control assembly  115  ( FIG. 1A ), indication lights on panel  119  ( FIG. 1A ) blink, foot pedals  118  are disabled and buzzer  324  ( FIGS. 6A-6C ) sounds. 
     At this stage, initialization of one of the two identical inflator/deflator assemblies  326  and  328  begins. Once initialization of one of the identical inflator/deflator assemblies is completed, initialization of the other of the identical inflator/deflator assemblies takes place. In the illustrated example, initialization of inflator/deflator assembly  326  occurs first, starting with closing of balloon valve  354  and opening of valve  352  thereof. After a predetermined period of time, typically 210 ms, piston  336  is positioned by motor  346  such that flange  338  is adjacent inflated balloon status sensor  344 . This is the state illustrated by  FIG. 6A . 
     The balloon valve  354  is then opened and valve  352  is closed. Following a predetermined time duration, typically 210 ms, piston  336  is moved by motor  346  such that flange  338  is adjacent ambient balloon status sensor  342 . This is the state illustrated by  FIG. 6B . 
     Following a further predetermined time duration, typically 4 seconds, valve  352  is opened. Following an additional predetermined time duration, typically 3 seconds, valve  352  is closed. 
     Following a still further predetermined time duration, typically 210 ms, piston  336  is moved by motor  346  such that flange  338  is adjacent deflated balloon status sensor  340 . This is the state illustrated by  FIG. 6C . 
     Following yet another predetermined time duration, typically four seconds, balloon valve  354  is closed. This completes initialization of inflator/deflator assembly  326  and is followed by initialization of inflator/deflator assembly  328 , which includes identical steps to those described above for initialization of inflator/deflector assembly  326 . 
     Following completion of initialization of inflator/deflator assemblies  326  and  328 , the indication lights on panel  119  ( FIG. 1A ) stop blinking and foot pedals  118  are enabled. At this stage, two vacuum indication lights, here designated by reference numerals  370  and  372  ( FIG. 1A ) are illuminated to indicate the presence of vacuum in balloons  108  and  127  ( FIG. 1A ). 
     At this stage, normally inflation of one of balloons  108  and  127  takes place. Usually, but not necessarily, inflation of balloon  108  takes place first. As seen in  FIG. 7C , inflation of balloon  108  is initiated by an operator pressing on one of the foot pedals  118 , here designated by reference numeral  380 , to send a signal to controller  323  ( FIGS. 6A-6C ) to initiate inflation of balloon  108 . Indication light  370  is extinguished and another one of the indication lights on panel  119 , a pressure indication light for balloon  108 , here designated by reference numeral  382  ( FIG. 1A ), begins blinking. Balloon valve  354  is opened. Following a predetermined time duration, typically 210 ms, piston  336  is positioned by motor  346  such that flange  338  is adjacent inflated balloon status sensor  344 . This is the state illustrated by  FIG. 6A . 
     At this stage, piston  336  is pressurized to a relatively high pressure, typically 200 mbar and the desired pressure at balloon  108  is typically 60 mbar. Inflation of the balloon  108  is accomplished by intermittently opening and closing balloon valve  354  and monitoring the pressure at sensor  360 , which is connected in series between piston  336  and balloon  108 . When the desired pressure at sensor  360  remains steady at 60 mbar for at least a predetermined time, typically one second, balloon valve  354  remains closed and inflation of balloon  108  is considered to be completed and indicator light  382  is illuminated continuously. Even following completion of inflation of balloon  108 , sensor  360  continues to monitor the pressure and if and when necessary, balloon valve  354  may be opened to top up the pressure at balloon  108 . 
     Inflation of balloon  127  is initiated by an operator pressing on one of the foot pedals  118 , here designated by reference numeral  384 , to send a signal to controller  323  ( FIGS. 6A-6C ) to initiate inflation of balloon  127 . Indication light  372  is extinguished and another one of the indication lights on panel  119 , a pressure indication light for balloon  108 , here designated by reference numeral  386  ( FIG. 1A ), begins blinking. Balloon valve  354  is opened. Following a predetermined time duration, typically 210 ms, piston  336  is positioned by motor  346  such that flange  338  is adjacent inflated balloon status sensor  344 . 
     At this stage, piston  336  is pressurized to a relatively high pressure, typically 200 mbar and the desired pressure at balloon  127  is typically 60 mbar. Inflation of the balloon  127  is accomplished by intermittently opening and closing balloon valve  354  and monitoring the pressure at sensor  360 , which is connected in series between piston  336  and balloon  127 . When the desired pressure at sensor  360  remains steady at 60 mbar for at least a predetermined time, typically one second, balloon valve  354  remains closed and inflation of balloon  127  is considered to be completed and indicator light  386  is illuminated continuously. Even following completion of inflation of balloon  127 , sensor  360  continues to monitor the pressure and if and when necessary, balloon valve  354  may be opened to top up the pressure at balloon  127 . 
     As seen in  FIG. 7D , deflation of balloon  108  takes place by an operator pressing on foot pedal  380 , to send a signal to controller  323  ( FIGS. 6A-6C ) to initiate deflation of balloon  108 . Indication light  382  is extinguished and vacuum indication light  370  begins blinking. Balloon valve  354  is closed. Following a predetermined time duration, typically 210 ms, piston  336  is positioned by motor  346  such that flange  338  is adjacent ambient balloon status sensor  342  and balloon valve  354  is opened. This is the state illustrated by  FIG. 6B . 
     At this stage, piston  336  is at approximately ambient pressure. Piston  336  is then positioned by motor  346  such that flange  338  is adjacent deflated balloon status sensor  340 . This is the state illustrated by  FIG. 6C . 
     Deflation of the balloon  108  is accomplished by monitoring the pressure at sensor  360 . When the desired pressure at sensor  360  reaches a negative level of −100 mbar, balloon valve  354  is closed, deflation of balloon  108  is considered to be completed and indicator light  370  is illuminated continuously. Even following completion of deflation of balloon  108 , sensor  360  continues to monitor the pressure inside balloon  108 . 
     Deflation of balloon  127  takes place by an operator pressing on foot pedal  384 , to send a signal to controller  323  ( FIGS. 6A-6C ) to initiate deflation of balloon  127 . Indication light  386  is extinguished and vacuum indication light  372  begins blinking. Balloon valve  354  is closed. Following a predetermined time duration, typically 210 ms, piston  336  is positioned by motor  346  such that flange  338  is adjacent ambient balloon status sensor  342  and balloon valve  354  is opened. This is a state corresponding to the state illustrated in  FIG. 6B . 
     At this stage, piston  336  is at approximately ambient pressure. Piston  336  is then positioned by motor  346  such that flange  338  is adjacent deflated balloon status sensor  340 . 
     Deflation of the balloon  127  is accomplished by monitoring the pressure at sensor  360 . When the desired pressure at sensor  360  reaches a negative level of −100 mbar, balloon valve  354  is closed, deflation of balloon  127  is considered to be completed and indicator light  372  is illuminated continuously. Even following completion of deflation of balloon  127 , sensor  360  continues to monitor the pressure inside balloon  127 . 
     One of the indicator lights on panel  119  may be a failure indication light, here designated by reference numeral  390 . This light may be illuminated when any of the functionalities described above fails to be fully performed. 
     Reference is now made to  FIGS. 8A and 8B , which are simplified partially cut-away illustrations of a balloon catheter  399  constructed and operative in accordance with a preferred embodiment of the present invention. As seen in  FIGS. 8A &amp; 8B , the balloon catheter of the present invention preferably comprises an inflation tube  400  which terminates at a cap  402 , which is attached at the interior of a distal end of inflation tube  400  and preferably includes at least two lumens, here designated by reference numerals  404  and  406 . A guide wire  410  preferably extends through lumen  404  and is fixed to cap  402  thereat, while lumen  406  is open for balloon inflation and deflation. 
     A distal end of the guide wire  410  preferably is fixed to a tip element  412 , preferably within a recess  414  formed therein. A balloon  420  is sealingly fixed, at a proximal end thereof, onto a distal end of inflation tube  400  and, at a distal end thereof, onto a proximal end of tip  412 . 
       FIG. 8A  shows balloon  420  in a non-inflated, ambient state wherein the walls of the balloon  420  are nearly taut but not appreciably tensioned. In this orientation, the guide wire  410  extends along an axis  421  generally parallel to and spaced from longitudinal axis  422  of the inflation tube  400 , cap  402  and tip  412 .  FIG. 8B  shows balloon  420  in a fully-inflated state, typically at a pressure of approximately 20-100 millibars. It is seen that inflation of balloon  420  causes guide wire  410  to be bowed in a preferably predetermined direction with respect to axis  422 , which direction is determined at least partially by the spatial relationship between axes  421  and  422 , and to an extent which is a predetermined function of the amount of inflation, thus resulting in a somewhat asymmetric, off-axis, inflated balloon configuration as seen. 
     According to a preferred embodiment of the present invention, the length of balloon  420  in its non-inflated, ambient state ( FIG. 8A ) is approximately 40-100 millimeters, and the length of balloon  420  in its fully-inflated state ( FIG. 8B ) is approximately 30-80 millimeters. In a specific configuration balloon  420 , in its non-inflated, ambient state, has a length of 80-95 millimeters, the corresponding length of balloon  420  in its fully-inflated state is 60-75 millimeters, and the diameter of balloon  420  in its fully-inflated state is 30-45 millimeters. 
     It is appreciated that the angle between the longitudinal axis of tip element  412  and axis  422  in the fully-inflated state ( FIG. 8B ) may be typically greater than 30 degrees, and may be approximately 90 degrees or more in the specific configuration of balloon  420  described hereabove. According to a preferred embodiment of the present invention, the angle between the longitudinal axis of the tip element  412  and axis  422  in the fully-inflated state is in the range of 40-75 degrees. Alternatively, the angle between the longitudinal axis of the tip element  412  and axis  422  in the fully-inflated state is in the range of 75-110 degrees. 
     It is appreciated that torque may be applied to tube  400  and/or guide wire  410 , thereby allowing an operator to rotate balloon  420  with tip element  412  around axis  422  during in vivo inspection of a tubular body portion, such as described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It is appreciated that inflation pressure in the range of 45-100 millibars may be suitable for anchoring the inflated balloon  420  and thus the balloon catheter to an generally tubular body portion to be inspected or treated, such as the intestine, as described for example in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It is appreciated that a generally higher inflation pressure may be applied to balloon  420 , as suitable. It is appreciated that guide wire  410  is sufficiently flexible to allow its bending during inflation of balloon  420  and to allow balloon  420  to be fully inflated when appropriate inflation pressure is applied. 
     As seen in  FIGS. 8A and 8B , inflation tube  400  protrudes into the internal volume of balloon  420  to a certain extent. In a preferred embodiment of the present invention, tube  400  protrudes between 7 to 20 millimeters into the internal volume of balloon  420 . It is appreciated that protrusion of inflation tube  400  into the internal volume of balloon  420  is useful for preventing or reducing blockage of inflation lumen  406  by balloon  420  in case of twisting of balloon  420  around axis  422  while being inflated. 
     Reference is now made to  FIGS. 9A, 9B, 9C, 9D, 9E and 9F , which are simplified, partially cut away, partially sectional, illustrations of the operation of the apparatus of  FIGS. 8A &amp; 8B . 
       FIG. 9A  illustrates the application of a partial vacuum, typically about −100 millibars, to the interior of balloon  420  via inflation tube  400  and lumen  406  of cap  402 . It is appreciated that due to the nearly taut, but not appreciably tensioned, arrangement of the balloon  420 , as described hereinabove with reference to  FIG. 8A , the maximum cross-sectional diameter of the balloon catheter, as indicated at reference numeral  430 , is relatively small, such as in the range of 2-4 millimeters, and preferably less than 3 mm, and is thus suitable for passage through an instrument channel of a conventional endoscope. 
       FIG. 9B  illustrates the balloon catheter of  FIGS. 8A-9A  located in an instrument channel  440  of a conventional endoscope  442 , located within the intestines of a patient. 
       FIG. 9C  illustrates the balloon catheter of  FIGS. 8A-9B  emerging from instrument channel  440 .  FIG. 9D  illustrates the balloon catheter of  FIGS. 8A-9B  located at an anchoring location forward of the end of the endoscope  442 .  FIG. 9E  illustrates the balloon catheter of  FIGS. 8A-9C  fully inflated at the anchoring location. It is seen that the guide wire  410  is bowed and thus the balloon  420  is generally asymmetric due to the inflation, as described above. 
       FIG. 9F  illustrates deflation of the balloon  420  by application of a partial vacuum, typically about −100 millibars, to the interior of balloon  420  via inflation tube  400  and lumen  406  of cap  402  and reinsertion thereof into instrument channel  440 , for removal from the patient. 
     Reference is now made to  FIGS. 10A and 10B , which are simplified, partially cut away, partially sectional, illustrations of a balloon catheter/external tube assembly constructed and operative in accordance with a preferred embodiment of the present invention. 
     As seen in  FIGS. 10A &amp; 10B , the balloon catheter/external tube assembly of the present invention preferably comprises an inflation tube  500  which terminates at a cap  502 , which is attached at the interior of a distal end of inflation tube  500  and preferably includes at least two lumens, here designated by reference numerals  504  and  506 . A guide wire  510  preferably extends through lumen  504  and is fixed to cap  502  thereat, while lumen  506  is open for balloon inflation and deflation. 
     A distal end of the guide wire  510  preferably is fixed to a tip element  512 , preferably within a recess  514  formed therein. A balloon  520  is sealingly fixed, at a proximal end thereof, onto a distal end of inflation tube  500  and, at a distal end thereof, onto a proximal end of tip  512 . 
     The inflation tube  500 , guide wire  510  and balloon  520  are at least partially located within an external tube  522 . External tube  522 , which may be similar in all relevant respects to external tube  122 , described hereinabove, may be attached to an endoscope (not shown), such as endoscope  104  ( FIGS. 1A &amp; 1B ), at multiple locations along its length by any suitable conventional means, such as medical adhesive tape or flexible bands (not shown). 
     A proximal end  524  of external tube  522  is typically open to enable a proximal end of inflation tube  500  coupled to balloon  520  to extend therefrom outside of a patient&#39;s body, thereby enabling insertion, removal and manipulation of the balloon catheter by an operator. Additionally, any other suitable endoscope tool may be inserted, removed or manipulated through tube  522 . The proximal end of inflation tube  500  may be coupled to an inflation control assembly, such as inflation control assembly  115  ( FIGS. 1A &amp; 1B ). 
     A distal end  529  of external tube  522  preferably extends slidably and telescopically through part of the length of a coil spring  530  which movably and slidably resides within a lumen  532 , which preferably forms part of a tubular sleeve  540 , which may be similar in all relevant respects to tubular sleeve  110  ( FIGS. 1A &amp; 1B ). The inflation tube  500 , guide wire  510  and balloon  520  are at least partially located within spring  530 . Preferably distal end  529  is beveled for ease of passage into and through coil spring  530 . It is a particular feature of the present invention that spring  530  defines a generally non-collapsible and highly flexible channel for the balloon catheter. 
       FIG. 10A  shows balloon  520  in a non-inflated, ambient state interior of spring  530  wherein the walls of the balloon  520  are nearly taut but not appreciably tensioned. In this orientation, the guide wire  510  and tip  512  extend along an axis parallel to and spaced from longitudinal axis  542  of the inflation tube  500  and cap  502 .  FIG. 10B  shows balloon  520  in a fully-inflated state forward of the external tube  522  and of spring  530 , typically at a pressure of approximately 20-100 millibars. It is seen that inflation of balloon  520  causes guide wire  510  to be bowed in a predetermined direction with respect to axis  542 , and to an extent which is a predetermined function of the amount of inflation, thus resulting in a somewhat asymmetric, off-axis, inflated balloon configuration as seen. 
     According to a preferred embodiment of the present invention, the length of balloon  520  in its non-inflated, ambient state ( FIG. 10A ) is approximately 40-100 millimeters, and the length of balloon  520  in its fully-inflated state ( FIG. 10B ) is approximately 30-80 millimeters. In a specific configuration balloon  520 , in its non-inflated, ambient state, has a length of 80-95 millimeters, the corresponding length of balloon  520  in its fully-inflated state is 60-75 millimeters, and the diameter of balloon  520  in its fully-inflated state is 30-45 millimeters. 
     It is appreciated that the angle between the longitudinal axis of tip element  512  and axis  542  in the fully-inflated state ( FIG. 10B ) may be typically greater than 30 degrees, and may be approximately 90 degrees or more in the specific configuration of balloon  520  described hereinabove. According to a preferred embodiment of the present invention, the angle between the longitudinal axis of the tip element  512  and axis  542  in the fully-inflated state is in the range of 40-75 degrees. Alternatively, the angle between the longitudinal axis of the tip element  512  and axis  542  in the fully-inflated state is in the range of 75-110 degrees. 
     It is appreciated that torque may be applied to tube  500  and/or guide wire  510 , thereby allowing an operator to rotate balloon  520  with tip element  512  around axis  542  during in vivo inspection of a tubular body portion, such as described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It is appreciated that inflation pressure in the range of 45-100 millibars may be suitable for anchoring the inflated balloon  520  and thus the balloon catheter to an generally tubular body portion to be inspected or treated, such as the intestine, as described for example in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It is appreciated that a generally higher inflation pressure may be applied to balloon  520 , as suitable. It is appreciated that guide wire  510  is sufficiently flexible to allow its bending during inflation of balloon  520  and to allow balloon  520  to be fully inflated when appropriate inflation pressure is applied. 
     As seen in  FIGS. 10A and 10B , inflation tube  500  protrudes into the internal volume of balloon  520  to a certain extent. In a preferred embodiment of the present invention, tube  500  protrudes between 7 to 20 millimeters into the internal volume of balloon  520 . It is appreciated that protrusion of inflation tube  500  into the internal volume of balloon  520  is useful for preventing or reducing blockage of inflation lumen  506  by balloon  520  in case of twisting of balloon  520  around axis  542  while being inflated. 
     Reference is now made to  FIGS. 11A, 11B, 11C, 11D, 11E and 11F , which are simplified, partially cut away, partially sectional, illustrations of the operation of the apparatus of  FIGS. 10A &amp; 10B . 
       FIG. 11A  illustrates the application of a partial vacuum, typically about −100 millibars, to the interior of balloon  520  via inflation tube  500  and lumen  506  of cap  502 . It is appreciated that due to the nearly taut, but not appreciably tensioned, arrangement of the balloon  520 , as described hereinabove with reference to  FIG. 10A , the maximum cross-sectional diameter of the balloon catheter, as indicated at reference numeral  544 , is relatively small, such as in the range of 2-4 millimeters, and preferably less than 3 mm, and is thus suitable for passage through the external tube  522  when coupled to a conventional endoscope  550 . 
       FIG. 11B  illustrates the balloon catheter of  FIGS. 10A-11A  located inside spring  530  interiorly of tubular sleeve  540 , forward of external tithe  522 , located within the intestines of a patient. 
       FIG. 11C  illustrates the balloon catheter of  FIGS. 10A-11B  emerging from spring  530 .  FIG. 11D  illustrates the balloon catheter of  FIGS. 10A-11C  located at an anchoring location forward of the end of the tubular sleeve  540 .  FIG. 11E  illustrates the balloon catheter of  FIGS. 10A-11D  fully inflated at the anchoring location. It is seen that the guide wire  510  is bowed and thus the balloon  520  is generally asymmetric due to the inflation, as described above. 
       FIG. 11F  illustrates deflation of the balloon  520  by application of a partial vacuum, typically about −100 millibars, to the interior of balloon  520  via inflation tube  500  and lumen  506  of cap  502  and reinsertion thereof into spring  530 , for removal from the patient or as needed during a procedure, for example for allowing better optical viewing of an organ during endoscopy. 
     Reference is now made to  FIG. 12 , which is a simplified illustration of a flexible endoscope system similar to that shown in  FIGS. 1A and 1B . The embodiment of  FIG. 12  is identical to that described hereinabove with reference to  FIGS. 1A and 1B  with the addition of a fluid communication port  610 , preferably a 3-port connector in which two of the three ports are arranged in line with the external tube  122 , for providing fluid communication with the interior of external tube  122 . The embodiment of  FIG. 12  also includes a drainage vessel  620 , associated with external tube  122  for receiving liquid, such as body fluids, from the interior of external tube  122 . 
       FIG. 13A  illustrates fluid communication port  610  arranged in line with external tube  122  and coupled to a fluid container, line or reservoir  630 , which may be, for example, a syringe, a source of gas under positive pressure, a vacuum source or a drainage vessel. 
     In accordance with a preferred embodiment of the present invention, an outer surface of inflation tube  126 , shown interiorly of external tube  122  and of port  610 , may be coated with a hydrophilic coating. A commercially available, hydrophilic coated, inflation tube  126  is a Slipskin™ coated PVC tube, available from MCTec of 9 Edisonstraat, Venlo, Netherlands. If water or a water-soluble material is injected into the external tube  122  outside of inflation tube  126 , passage of inflation tube  126  through external tube  122  is greatly facilitated by a resulting reduction in friction. 
       FIG. 13B  illustrates drainage vessel  620  coupled in-line with external tube  122  and configured as a cylinder which is coaxial with external tube  122  to allow collection of drainage liquid irrespective of the orientation of the external tube  122 . 
     Reference is now made to  FIGS. 14A, 14B, 14C &amp; 14D , which are simplified, partially cut away, partially sectional, illustrations of the operation of an endoscope tool  128  as shown and described hereinabove with reference to  FIGS. 2A-3B , including a balloon catheter  399  as shown and described hereinabove with reference to  FIGS. 8A &amp; 8B , extending through an instrument channel  440  of an endoscope  442 , such as that shown and described hereinabove with reference to  FIGS. 9B-9F , in a specific context, the junction between the colon and the small intestine at the ileo-cecal valve, designated by reference numeral  650 . 
       FIGS. 14A and 14B  together show bending of endoscope tool  128 , located in the colon, such that distal portion  178  and tip element  170  are directed through ileo-cecal valve  650 .  FIG. 14C  shows anchoring of the balloon catheter  399  in the small intestine by inflation of balloon  420 , causing bowing of guide wire  410 .  FIG. 14D  shows forward displacement of endoscope  442  along endoscope tool  128  through the ileo-cecal valve  650 . 
     Reference is now made to  FIGS. 15A and 15B , which are respective exploded and partially cut-away pictorial illustrations of a catheter or endoscope tool and associated inflation tube, constructed and operative in accordance with another preferred embodiment of the present invention. 
     As seen in  FIGS. 15A &amp; 15B , an inflation tube  726  preferably includes at least two lumens, here designated by reference numerals  728  and  730 . A selectable steering wire  732  preferably extends through lumen  728 . Lumen  730  is a balloon inflation lumen and extends through a relatively narrow distal portion  734  of the inflation tube which extends forward of distal end of lumen  728  and communicates with a balloon inflation port  736 . 
     A collar  740  preferably fixedly attaches a distal end of selectable steering wire  732  to the distal portion  734  forwardly of at least one indentation  742 . In this embodiment, the attachment location, designated by reference numeral  744 , of the distal end of the selectable steering wire  732  to the distal portion  734  of the inflation tube  726  by collar  740  lies within a balloon  750 . 
     A distal end of the distal portion  734  of the inflation tube  726  preferably is fixed to a tip element  752 , preferably within a recess  754  formed therein. Balloon  750  is sealingly fixed, at a proximal end thereof, onto a distal end of inflation tube  726  and, at a distal end thereof, onto a proximal end of tip element  752 . 
     Reference is now made to  FIGS. 16A &amp; 16B , which are sectional illustrations of the catheter or endoscope tool of  FIGS. 15A &amp; 15B  in respective straight and bent operative steering orientations.  FIG. 16A  shows the catheter or endoscope tool extending along a longitudinal axis  760 . In  FIG. 16B , it is seen that when selectable steering wire  732  is retracted relative to inflation tube  726 , as indicated by arrow  762 , it applies a pulling force to a forward part of the distal portion  734  lying forwardly of at least one indentation  742 , causing that forward part of distal portion  734  and tip element  752  to rotate in a direction indicated by arrow  770  relative to longitudinal axis  760 . Preferably the distal portion  734  is sufficiently resilient under such bending so as to return to its axial orientation shown in  FIG. 16A  once selectable steering wire  732  is released. 
     It is appreciated that torque may be applied to inflation tube  726 , thereby allowing an operator to rotate balloon  750  with tip element  752  around axis  760  during in vivo inspection of a tubular body portion, such as described in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     Reference is now made to  FIGS. 17A and 17B , which are simplified illustrations of a portion of an alternative embodiment of the flexible endoscope system of  FIGS. 1A and 1B , in respective deflated and inflated operative orientation at an anchoring location in the small intestine. As seen, a peripheral balloon  800  surrounds a tubular sleeve  802 , which may be similar in all relevant respects to tubular sleeve  110  ( FIGS. 1A &amp; 1B ). 
     Preferably, peripheral balloon  800  includes a forward facing portion  810  and a rearward facing portion  812 , separated by a central portion  814 . It is a particular feature of the present invention that both the forward facing portion  810  and the rearward facing portion  812  are tapered, both when deflated, as seen in  FIG. 17A , and when inflated, as seen in  FIG. 17B . It is a further particular feature of the present invention that the slope of the forward facing portion  810  is different than, greater than and opposite to that of rearward facing portion  812 . 
     According to a preferred embodiment of the present invention, the slope of rearward facing portion  812 , when inflated, is greater than 45 degrees and more preferably greater than 60 degrees, and the slope of the forward facing portion  810 , when inflated, is less than 60 degrees and more preferably less than 45 degrees. 
     In a specific embodiment of the present invention, the slope of the forward facing portion  810  is approximately 45 degrees and the slope of the rearward facing portion  812  is approximately 60 degrees. This is particularly helpful during an endoscopy procedure, as described for example in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     For example, a small slope of forward facing portion  810  when the balloon  800  is not fully inflated may allow more efficient and lower friction advancement of an endoscope assembly for in vivo inspection of a generally tubular body portion such as an intestine, as described for example in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     A high slope of rearward facing portion  812 , for example, may prevent or minimize slippage and undesired withdrawal of an endoscope assembly during in vivo inspection of a generally tubular body portion such as an intestine, as described for example in one or more of applicant/assignee&#39;s PCT Application No. PCT/IL2005/000152, filed Feb. 7, 2005; PCT Application No. PCT/IL2005/000849, filed Aug. 8, 2005, and PCT Application No. PCT/IL2007/000600, filed May 17, 2007, the disclosures of which are hereby incorporated by reference. 
     It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described herein above. Rather the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove as well as variations and modifications which would occur to persons skilled in the art upon reading the specifications and which are not in the prior art.