Patent Publication Number: US-2009240109-A1

Title: Flexible endoscope with core member

Description:
CROSS-REFERENCE TO RELATED CASES 
     This application claims priority to, and the benefit of Provisional U.S. Patent Application Serial No. 61/038,872, filed Mar. 24, 2008, the entirety of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to endoscopes for use during a medical procedure. 
     BACKGROUND INFORMATION 
     Medical devices are used to access regions of the body to deliver diagnostic or therapeutic agents to those regions and to perform surgical procedures on those regions. For example, endoscopes may use body airways and canals to access the colon, esophagus, stomach, urethra, bladder, ureter, kidneys, lungs, bronchi, or uterus. Catheters may use the circulatory system as pathways to access treatment sites near the heart or may use the urinary canal to access urinary regions. 
     Medical devices are often introduced into the body through a large artery such as those found in the groin or in the neck. The devices are often passed through ever-narrower arteries until they can reach the operative site inside the body. Many such pathways may curve, loop around, and even wind back. In order to navigate the device through the pathways to the operative site, the device must be flexible to allow bending, yet have enough column strength to prevent buckling as the device is pushed. 
     SUMMARY OF THE INVENTION 
     In one type of endoscope, the image is transmitted by an imaging fiber bundle, which occupies the central, or near central, space of the endoscope shaft. In another type of endoscope, an electrical signal is transmitted from a small camera (such as a CCD or other image sensor) at or near the tip of the endoscope to a display unit, where the signal gets converted into an image for display to an operator of the endoscope. The one or more wires for transmitting the signal occupy less space in the shaft than a fiber bundle occupies in a more traditional endoscope that does not employ electronic imaging. 
     The present invention generally relates to an endoscope with an elongated shaft with a core member for imparting flexibility and column strength to the shaft. When located at or near the central axis of the endoscope, this allows the core member to add substantially to the column strength of the device while not adding significant bending stiffness due to low moment of inertia. The core member can occupy the space within the shaft that was traditionally occupied by the imaging fiber bundle, when an electronic imaging device is used at or near the end of the shaft of the endoscope and one or wires within the shaft carry signals from the imaging device. 
     In one aspect, the invention features an endoscope with a handle and an elongated shaft. The handle is at the proximal end of the endoscope and is used to control the endoscope as it is advanced through body pathways to the operative site. The shaft extends distally from the proximal handle. At least part of the shaft, or the entire shaft, comprises an inner member, a core member, and an outer member. The inner member defines at least three lumens. A first lumen is for receiving an instrument. A second lumen is for receiving one or more wires for connecting a camera at a distal portion of the shaft to a display unit. A third lumen is for receiving a core member. The core member is flexible and provides column strength to the shaft. The outer member is disposed over the inner member of the shaft. The outer member defines a lumen through which the inner member extends. 
     According to one exemplary embodiment of the present invention, an endoscope includes a proximal handle and an elongated shaft extending distally from the proximal handle. At least a portion of the shaft has an inner member defining a first lumen for receiving an instrument, a second lumen for receiving one or more wires for connecting a camera at a distal portion of the elongated shaft to a display unit, and a third lumen. A core member extending through the third lumen of the inner member is flexible and provides column strength to the at least a portion of the shaft. An outer member is disposed over the inner member and defines a lumen through which the inner member extends. 
     In one aspect, the endoscope of the present invention can be a ureteroscope, a colonoscope, a hysteroscope, a uteroscope, bronchoscope, or a cystoscope. The first lumen can be used for receiving a light-carrying device, a surgical instrument, or a fluid-carrying device. The inner member can be made from a plastic such as silicone or pebax. The outer member can also be made from a plastic material. 
     In a further aspect of the present invention, the core member of the endoscope further includes a proximal portion and a distal portion coupled to the proximal portion. The proximal portion can be made from a first material and the distal portion can be made from a second material where the first material is less flexible than the second material. The core member can be a hollow tube and can have a circular cross section or a rectangular cross section. The proximal portion has a first diameter or thickness and the distal portion has a second diameter or thickness where the first diameter or thickness is larger than the second diameter or thickness. The distal portion can also be tapered. 
     In another aspect of the present invention, the core member also includes a transitional portion coupling the proximal portion to the distal portion. The proximal portion can have a circular cross section and the distal portion can have a rectangular cross section and the cross section of the transitional portion progressively changes from circular to rectangular. 
     In yet a further aspect of the present invention the core member has a circular cross section and the proximal portion has a first diameter and includes a deflection portion having a second diameter that is smaller than the first diameter to promote deflection of the elongated shaft along the deflection portion. The core member can also have a rectangular cross section and the proximal portion has a first thickness and includes a deflection portion having a second thickness that is smaller than the first thickness to promote deflection of the elongated shaft along the deflection portion. The distal portion can also include such a deflection portion having a cross sectional area that is smaller than the distal portion cross sectional area to promote deflection of the elongated shaft along the deflection portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and operation of various embodiments according to the present invention, reference is made to the following description taken in conjunction with the accompanying drawing figures which are not necessarily to scale and wherein like reference characters denote corresponding or related parts throughout the several views. 
         FIG. 1  is a diagram of an endoscope with a proximal handle and an elongated shaft extending distally from the proximal handle. 
         FIG. 2A  is a diagram depicting at least a portion of the elongated shaft. 
         FIG. 2B  is a diagram depicting the axial structure of a proximal portion of the elongated shaft. 
         FIG. 2C  is a diagram depicting the axial structure of a distal portion of the elongated shaft. 
         FIG. 2D  is a diagram depicting an embodiment of the elongated shaft in which the core member has a rectangular cross section. 
         FIG. 3A  is a diagram depicting a configuration of the core member with a circular cross section and including a proximal portion and a distal portion, the proximal portion having a larger diameter than the distal portion. 
         FIG. 3B  is a diagram depicting the flexibility of the proximal and distal portions of the core member. 
         FIG. 3C  is a diagram depicting 360 degrees of bendability of the core member with a circular cross section. 
         FIG. 4A  is a diagram depicting a configuration of the core member, wherein the distal portion of the core member has a diameter that tapers from a proximal end to a distal end of the distal portion. 
         FIG. 4B  is a diagram depicting the increasing flexibility of the core member toward the distal end of the distal portion, the distal portion having a tapering diameter. 
         FIG. 5A  is a diagram depicting a configuration of the core member with a rectangular cross section and including a proximal portion and a distal portion, the proximal portion having a larger thickness than the distal portion. 
         FIG. 5B  is a diagram depicting how the core member with a rectangular cross section promotes flexibility in a single plane. 
         FIG. 6  is a diagram depicting a configuration of the core member, wherein the distal portion of the core member has a thickness that tapers from a proximal end to a distal end of the distal portion. 
         FIG. 7  is a diagram depicting a configuration of the core member where the core member is a hollow tube and the core member includes a proximal portion with a first diameter and a distal portion with a second diameter, the first diameter being larger than the second diameter. 
         FIG. 8A  is a diagram depicting a configuration of the core member with a proximal portion comprised of a first material and distal portion comprised of a second material, the first material being less flexible than the second material. 
         FIG. 8B  shows an example of how the first material of the core member of  FIG. 8A  is more flexible than the second material of the core member of  FIG. 8A . 
         FIG. 9A  is a diagram depicting a configuration of the core member with a proximal portion, a distal portion, and a transitional portion coupling the proximal and distal portions. The core member has a circular cross section and the proximal portion has a first diameter and the distal portion has a second diameter that is smaller than the first diameter. The transitional portion has a diameter that reduces from the first diameter to the second diameter. 
         FIG. 9B  is a diagram depicting a configuration of the core member with a proximal portion, a distal portion, and a transitional portion coupling the proximal and distal portions. The core member has a rectangular cross section and the proximal portion has a first thickness and the distal portion has a second thickness that is smaller than the first thickness. The transitional portion has a thickness that reduces from the first thickness to the second thickness. 
         FIG. 10  is a diagram depicting a configuration of the core member, wherein the transitional portion has a cross section that progressively changes from circular to rectangular. 
         FIG. 11  is a diagram depicting a configuration of the core member, wherein the core member is a hypotube with a proximal portion, a distal portion, and a transitional portion, the transitional portion having a helically cut slot with a first pitch, and the distal portion having a helically cut slot with a second pitch, the first pitch being larger than the second pitch to promote more flexibility in the distal portion than in the transitional and proximal portions. 
         FIG. 12  is a diagram depicting a configuration of the core member with a circular cross section, wherein the proximal portion has a deflection portion with diameter reduced from the diameter of the proximal portion to promote 360 degrees of flexibility along the deflection portion. 
         FIG. 13A  is a diagram depicting a configuration of the core member with a rectangular cross section, wherein the proximal portion has a deflection portion with thickness reduced from the thickness of the proximal portion to promote a single plane of flexibility along the deflection portion. 
         FIG. 13B  is a diagram depicting the core member of  FIG. 13A  bending in the single plane of flexibility at the deflection portion, where the thinner side of the core member is in the plane. 
     
    
    
     DESCRIPTION 
       FIG. 1  shows an endoscope  50  with a proximal handle  52 , an opening  54  for receiving a medical instrument, a viewing eyepiece  56 , and an elongated shaft  100 . At the tip  60  of the endoscope is a camera  58 . The camera  58  can be a charge coupled device (CCD) or other type of image sensor useful for capturing images and/or full-motion video images in digital (or some other) format and then transmitting those images as electrical signals from the camera  58  back through one or more wires  258  extending within the shaft of the endoscope to a display unit  62 . The tip  60  of the endoscope also may contain one or more light emitting diodes (LEDs) for illuminating internal body pathways and surgical sites inside a patient such as a human or other mammal. Fiber optics can also be used for illumination, although it can add stiffness and potentially take up more cross-sectional area. The elongated shaft  100  extends distally from the proximal handle  52 . The terms proximal and distal require a point of reference. In this application, the point of reference is the perspective of the user. Therefore, the term proximal will always refer to an area closest to the user, whereas distal will always refer to an area away from the user. 
     The endoscope  50  can be any of a variety of types of scopes used in any of a variety of medical procedures. For example, the endoscope  50  can be a ureteroscope, a colonoscope, a hysteroscope, a uteroscope, bronchoscope, or a cystoscope. 
       FIG. 2A  shows a portion the elongated shaft  100 . The right side  252  of the elongated shaft  100  shown in  FIG. 2A  extends distally from the proximal handle  52 . The left side  260  of the elongated shaft shown in  FIG. 2A  can be located at a distal portion  61  of the medical device  50 , or it can be the distal tip  60  of the medical device  50 .  FIG. 2B  is a cross-section of the shaft at line  2 B- 2 B of  FIG. 2A .  FIG. 2C  is a cross-section of the shaft at line  2 C- 2 C of  FIG. 2A . All relative descriptions herein such as top, bottom, left, right, up, and down are with reference to the figures, and thus should not be construed in a limiting sense. 
     As shown in  FIGS. 2A ,  2 B, and  2 C, at least a portion of the shaft includes an inner member  214 , a core member  220 , and an outer member  210 . The inner member can be made of a polymer, which can include polyethylene, polyvinyl chloride (PVC), polyurethane, teflon, polypropylene, nylon, polyether block amide sold under the trade name PEBAX, silicone, co-polymers, and other polymers. The inner member defines a first lumen  212  for receiving a medical instrument. The inner member may include one or more first lumens  212  for receiving a variety of instruments such as forceps, catheters, fiber optics, and other instruments. The inner member  214  also defines a second lumen  216  for receiving one or more wires  258  for connecting the camera  58  at a distal portion of the endoscope, for example, near or at the tip of the endoscope  50 , to a viewing eyepiece  56  or display unit  62 . 
     The inner member  214  also defines a third lumen  218 . A core member  220  extends through the third lumen  218 . The core member imparts column strength to the at least a portion of the elongated shaft, allowing the shaft to resist buckling as it is pushed through body pathways. The core member can occupy the space inside the endoscope that was traditionally occupied by imaging fiber optics, which have been replaced in the endoscope with the one or more camera wires  258 . 
     The core member  220  can include a number of different configurations depending on the requirements of the endoscope. For example, different portions of the core member can be comprised of different materials with varying degrees of flexibility. Alternatively, the core member can be comprised of the same material with different cross sections, for example, circular or rectangular, with varying diameter or thickness. A combination of both material and cross section can be used. 
     In one embodiment according to the invention, the core member  220  includes a proximal portion  221  and a distal portion  222  coupled to the proximal portion. As shown in  FIG. 3A , the core member  220  can have a circular cross section  300 . The proximal portion  221  can have a first diameter  321  and the distal portion  222  can have a second diameter  322 . The first diameter is larger than the second diameter, imparting to the core member more flexibility over the distal portion  222  than the proximal portion  221 , as shown in  FIG. 3B . The circular core member can be used to impart 360 degrees of deflection  340  of the core member  220 , as shown in  FIG. 3C . In a further embodiment, the first diameter  321  of the proximal portion  221  is between 0.5 and 1.0 millimeters, and the second diameter  322  of the distal portion  222  is between 0.1 and 0.3 millimeters. 
     In another embodiment shown in  FIG. 4A , the distal portion  222  has a proximal end  422  coupled to the proximal portion  221 , and a distal end  432 . The distal portion has a diameter that tapers  450 ,  450 ′, and  450 ″ from the proximal end, where the diameter is largest, to the distal end, where the diameter is smallest. In this way, the distal portion  221  is progressively more flexible  432 ,  432 ′, and  432 ″ toward the distal end  422  than at the proximal end  422 , as shown in  FIG. 4B . 
     In one embodiment shown in  FIG. 5A , the core member  220  has a rectangular cross section  500 . The proximal portion can have a first thickness  521  and the distal portion can have a second thickness  522 . The first thickness  521  is larger than the second thickness  522 . The rectangular core member can be used to promote deflection  540  of the core member  220  in a single plane  542 , with the shorter side of the core member  550  in the bending plane, as shown in  FIG. 5B . 
     In another embodiment shown in  FIG. 6 , the distal portion  222  has a proximal end  622  coupled to the proximal portion  221 , and a distal end  632 . The distal portion has a thickness that tapers  650 ,  650 ′, and  650 ″ from the proximal end, where the thickness is largest, to the distal end, where the thickness is smallest. In this way, the distal portion  221  is progressively more flexible toward the distal end  632  than at the proximal end  622 . 
     In one embodiment shown in  FIG. 7 , the core member  220  can be a hollow tube with a proximal portion  221  and a distal portion  222  coupled to the proximal portion. The proximal portion can have a first diameter  751  and the distal portion can have a second diameter  752 . The first diameter is larger than the second diameter, imparting to the core member more flexibility over the distal portion than the proximal portion. Instruments or other surgical devices can be disposed in the hollow core member. 
     In one embodiment shown in  FIGS. 8A and 8B , the core member  220  can include a proximal portion  221  comprised of a first material  721  and a distal portion  222  coupled to the proximal portion  221  and comprised of a second material  722 . The first material can be less flexible than the second material, imparting more flexibility to the distal portion as shown in  FIG. 8B . The first material can be stainless steel, and the second material can be a shape memory alloy such as a Nitinol™ (an alloy of nickel and titanium). Examples of other materials include tungsten alloys, and other more malleable alloys, including gold, platinum, palladium, rhodium, etc. The class of alloys known as super-elastic alloys can also be used, including titanium. Non-metal materials with varying amounts of flexibility, for example, composite materials, could also be used. 
     In any of  FIGS. 2A ,  2 B, and  2 C, the outer member  210  can be covered with a lubricious material  211  that makes it “slippery” on its outer surface. One such material  211  is known as Teflon, which is a trademark used for a waxy, opaque material called polytetrafluoroethylene. In one embodiment, the outer member  210  comprises a plastic or a polymer, which can include polyethylene, polyvinyl chloride (PVC), PEBAX, silicone, co-polymers, and other polymers. The outer member can be heat shrunk over the inner member  214  into tight engagement with the inner member. The outer member can be secured to the inner member with an adhesive applied on the outer surface of the inner member or at various affixation points on the outer surface of the inner member. The adhesive can be a thermo-plastic adhesive that softens at the temperature necessary to heat shrink the outer member. 
     In one embodiment shown in  FIG. 9A , the core member  220  includes a proximal portion  221 , a distal portion  222 , and a transitional portion  830  coupling the proximal portion to the distal portion. The core member  220  can have a circular cross section  800 , and the proximal portion can have a first diameter  821  and the distal portion can have a second diameter  822 , the first diameter being larger than the second diameter. The transitional portion  830  has a tapered diameter that reduces  840  from the first diameter  821  to second diameter  822 . In another embodiment shown in  FIG. 9B , the core member  220  can have a rectangular cross section  801 , and the proximal portion can have a first thickness  831  and the distal portion can have a second thickness  832 , the first thickness being larger than the second thickness. The transitional portion  830  can have a tapered thickness that reduces  850  from the first thickness to the second thickness. 
     In another embodiment shown in  FIG. 10 , the proximal portion  221  can have a circular cross section  900  and the distal portion  222  can have a rectangular cross section  901 . The transitional portion  830  can have a cross section that progressively changes from circular where the transitional portion is coupled to the proximal portion at  832  to rectangular where the transitional portion is coupled to the distal portion at  834 . In another embodiment, the transitional portion includes an outer surface  850 , wherein the progressive change comprises a flattening on four sides  852 ,  853 ,  854 , and  855  of the outer surface  850 , starting from the circular portion of the transitional portion and ending at the rectangular portion of the transitional portion, such that the transitional portion cross-section progressively changes from a rectangular to circular. 
     In one embodiment shown in  FIG. 11 , the core member  220  is a hollow tube and includes a proximal portion  221 , a distal portion  222 , and a transitional portion  830  coupling the proximal and distal portions. The transitional portion has a helically cut slot  1000  with a pitch  1001  defined as the distance between adjacent slots. The distal portion has a helically cut slot  1002  with a pitch  1003  defined as the distance between the adjacent slots. The pitch of the transitional portion  1001  can be greater than the pitch of the distal portion  1003 , resulting in the transitional portion being less flexible than the distal portion. 
     In one embodiment shown in  FIG. 12 , the core member  220  has a circular cross section  1100 , and the proximal portion has a first diameter  1131  and includes a deflection portion  1102  with a second diameter  1133  that is smaller than the first diameter. The deflection portion  1102  promotes deflection of the core member along the deflection portion. In another embodiment shown in  FIG. 13A , the core member  220  has a rectangular cross section  1200  and the proximal portion  221  has a first thickness  1231  and includes deflection portion  1202  with a second thickness  1233  that is smaller than the first thickness. At shown in  FIG. 13B , the deflection portion  1202  promotes deflection  1250  in a single plane  1251 , with the shorter side  1252  of the core member in the deflection plane. In some embodiments, for example in a ureteroscope, he center point  1160  of the deflection portion can be between 8 and 15 centimeters from the distal end of the elongated shaft  100 , although other dimensional ranges may be appropriate for other medical applications. In another embodiment, the distal portion has a deflection portion with a smaller diameter or thickness than the distal portion. 
     The assembling procedure for the endoscope  50  and elongated shaft  100  can include extruding the inner member  214  inside the lumen of the outer member  210 . Alternatively, the outer member  210  can be heat-shrunk over the inner member  214 . The first lumen  212 , second lumen  216 , and third lumen  218  can be built into the inner member. The core member  220  can be inserted into the third lumen and locked into place with glue or other type of adhesive. The core member can include the proximal portion  221  and distal portion  222  constructed with varying flexibility and column strength as described above to meet the design needs for the endoscope. The space between the reduced diameter or thickness portion of the core member can be filled with a soft material  224 . 
     An endoscope according to the invention has a variety of advantages over known structures. For example, an endoscope according to the invention can be less expensive to manufacture than known endoscopes. Another advantage is that use of a central core member can reduce the overall diameter of the shaft of the endoscope as compared to known endoscopes, making the inventive endoscope less invasive. 
     While certain embodiments according to the invention are shown and described, other embodiments are within the scope of this disclosure and are considered to be part hereof. The invention is not to be limited just to certain embodiments shown and/or described.