Abstract:
An improved wire guide and method for cannulating a bodily lumen, such the biliary tree are provided for procedures such as endoscopic retrograde cholangiopancreatography (ECRP). The wire guide and cannulation method minimizes the potential for trauma to the ducts while reducing the chances of disconnecting the wire guide from newer access devices. Generally, the wire guide includes an atraumatic tassel tip which is operable between delivery and deployed configurations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 60/797,100, filed on May 3, 2006, entitled “TASSEL TIP WIRE GUIDE,” the entire contents of which are incorporated herein by reference. 
     
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to wire guides for intracorporeal procedures, and more particularly relates to wire guides for assisting in cannulation during endoscopic procedures such as endoscopic retrograde cholangiopancreatography (ERCP). 
       BACKGROUND OF THE INVENTION 
       [0003]    ERCP is a study of the ducts that drain the liver and pancreas. Generally, the liver produces bile that is concentrated by the gallbladder and delivered to the duodenum (upper small intestine) via the common bile duct. The pancreatic duct joins the bile duct at the papilla of Vater where they drain into the duodenum through the sphincter of Oddi. ERCP generally includes cannulation of the biliary tree (which includes the bile duct, pancreatic duct, and hepatic ducts of the liver) by delivering a catheter through the working channel of a duodenoscope and into the biliary tree. A contrast medium is injected through the catheter to provide for diagnosis of problems in the liver, gallbladder, biliary tree and pancreas, such as gallstones, inflammatory strictures, leaks or cancer. Exemplary ERCP catheters are described in U.S. Pat. Nos. 5,320,602 and 5,383,849. 
         [0004]    A wire guide is often used to assist in navigation of the catheter (or other endoscopic access devices such as sphinctertomes, balloons, biopsy devices, stent delivery catheters, dilators, etc.) through the sphincter of Oddi and into the biliary tree, often referred to as cannulation. Wire guides may also be used for deep cannulation of the biliary tree. Wire guides, however, carry the risk of trauma to structured segments of the bile or pancreatic ducts which can result in life-threatening infection, perforation or pancreatitis. Additionally, with the advent of new access devices permitting rapid exchange of multiple devices without the need for traditional “over the wire” or “long wire” exchanges (see, e.g., U.S. Pat. Pub. No. 2005/0059890, the disclosure of which is hereby incorporated by reference in its entirety) there exists the possibility for unintentional disconnection of the access device and wire guide. 
         [0005]    Accordingly, there exists a need for a wire guide that assists in cannulation of the biliary or pancreatic ducts and minimizes the potential for trauma to the ducts. At the same time, it would also be desirable to reduce the chances of disconnection of the wire guide from newer access devices providing rapid exchange. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention provides an improved wire guide and method for cannulating a bodily lumen such the biliary tree. The wire guide and cannulation method minimizes the potential for trauma to the ducts while reducing the chances of disconnecting the wire guide from newer access devices. 
         [0007]    According to one embodiment constructed in accordance with the teachings of the present invention, the wire guide includes the main body having a distal end, and a tassel tip formed at the distal end. The tassel tip is defined by a plurality of strands having free end portions. The tassel tip is operable between a delivery configuration and a deployed configuration. The free end portions of the plurality of strands are positioned adjacent the longitudinal axis in the delivery configuration, and are spaced radially from the longitudinal axis in the deployed configuration. The strands curve away from the longitudinal axis to define atraumatic peaks in the deployed configuration. 
         [0008]    According to more detailed aspects, each strand further includes a connecting portion and a middle portion between the connecting portion and the free end portion. The middle portion is curved in the deployed configuration to define atraumatic peaks for safe navigation of the wire guide. The free end portions are positioned distally relative to the middle portions in the delivery configuration, and the free end portions are positioned proximally relative to the middle portions in the deployed configuration. The free ends of the plurality of strands are radially spaced apart a distance greater than a diameter of the main body, and thus form an umbrella shape at the distal end. The plurality of strands preferably extend proximally along side the outside of the main body. The plurality of strands are formed of a flexible material having sufficient strength to form the umbrella shape in the deployed configuration. 
         [0009]    According to still further aspects, the distal end of the main body may be constructed of a plurality of wires or may be constructed of a solid or tubular wire. When the distal end of the main body is constructed of a plurality of wires, the distal portions of the plurality of wires may be used to form the plurality of strands of the tassel tip. A hub at the distal end of the main body is used to band together the plurality of wires. When the distal end of the main body is constructed as a solid wire, the distal portion preferably includes a plurality of channels receiving a portion of the plurality of strands to reduce the overall package size, or alternatively the strands may be unitarily and integrally formed from the solid wire. 
         [0010]    According to another embodiment in accordance with the teachings of the present invention, a method for performing cannulation of a bodily lumen is provided. The method generally includes the steps of coupling the above-described wire guide to an access device, whereby the plurality of strands are contained within a passageway of the access device. The wire guide is translated distally relative to the access device, the distal movement of the tassel tip causes it to take a deployed configuration wherein the middle portion of each of the strands curves to define atraumatic peaks for safe navigation of the wire guide within the bodily lumen. Preferably, the bodily lumen is the biliary tree of a mammalian patient, and the method further includes a step of placing a duodenoscope into the duodenum of the patient. Here, the advancing step includes passing the wire guide and access device as a unit through a channel of the duodenoscope and through a sphincter of Oddi leading to the biliary tree. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings: 
           [0012]      FIG. 1  depicts a perspective view of a wire guide constructed in accordance with the teaching of the present invention; 
           [0013]      FIG. 2  depicts a cross-sectional view, taken from the side, of the wire guide depicted in  FIG. 1 ; 
           [0014]      FIG. 3  depicts a cross-sectional view, taken about the line  3 - 3  of  FIG. 2 ; 
           [0015]      FIG. 4  depicts a side view, partially in cross-section, of a delivery configuration of the wire guide depicted in  FIGS. 1-3 ; 
           [0016]      FIG. 5  depicts a cross-sectional view of an alternate embodiment of the wire guide depicted in  FIGS. 14 ; 
           [0017]      FIG. 6  depicts a cross-sectional view of yet another alternate embodiment of the wire guide depicted in  FIGS. 14 ; 
           [0018]      FIG. 7  depicts a cross-sectional view, taken about the line  7 - 7  of  FIG. 6 ; 
           [0019]      FIG. 8  depicts a schematic view, partially in cross-section, of the wire guide of  FIGS. 1-4  in the process of cannulating the biliary tree; 
           [0020]      FIG. 9  depicts a cross-sectional view of still yet another alternate embodiment of the wire guide depicted in  FIGS. 1-4 ; 
           [0021]      FIG. 10  is a cross-sectional view taken about the line  10 - 10  of  FIG. 9 ; 
           [0022]      FIG. 11  is a cross-sectional view of the wire guide depicted in  FIGS. 9-10  shown in a deployed configuration; and 
           [0023]      FIG. 12  is a cross-sectional view of an alternate tip configuration for the wire guide depicted in  FIGS. 9-11 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Turning now to the figures,  FIG. 1  depicts a deployed configuration of a wire guide  20  constructed in accordance with the teachings of the present invention. The wire guide generally includes the main body  22  having a distal end  24  which includes a tassel tip  30 . The tassel tip  30  is formed by a plurality of strands  32 . Preferably the number of strands  32  is greater than or equal to 3, and the currently preferred configuration of four strands has been depicted in the figures. Each of the strands  32  is constructed of a flexible material that permits them to retroflex, i.e. curve away from a longitudinal axis of the wire guide  20  and extend proximally to form an umbrella or tassel shape as shown in  FIG. 1 . The length of tassels  32  and their flexibility are selected to provide the desired curvature having atraumatic peaks  34  to prevent damage to the bodily structures being navigated. 
         [0025]    The strands  32  may be hydrophilic and/or radiopaque. For example, the strands  32  may be formed of a metal such as platinum, stainless steel, or an alloy such as a superelastic alloy of nickel titanium, and can further include a hydrophilic coating that can be formed of a hydrophilic polymer such as polytetrafluorethylene (PTFE), Teflon(™), silicone, glycerin, modified polyurethanes or various blends. Of course, the strands  32  can be formed of suitable plastics such as polytetrafluorethylene (PTFE), polyethylene ether ketone (PEEK), polyvinylchloride (PVC), polyamide including Nylon®, polyimide, polyurethane, polyethylene (high, medium or low density), and elastomers such as Santoprene®, the plastic being selected (or combined with other materials) to provide the desired properties noted above. The construction of the strands  32  exhibits a suitable balance between flexibility and strength to form the depicted umbrella shape and define the atraumatic peaks  34 . Preferably each strand  32  has a diameter less than or equal to the radius of the main body  22 , depending on material selection. 
         [0026]    As best seen in  FIGS. 2 and 3 , the main body  22  of the wire guide includes a plurality of wires  26  disposed over a mandrel  28 . It will be recognized that the mandrel  28  may be dispensed with, and the wires  26  may be stranded together such as by twisting or braiding. Preferably, the number of wires  26  equals the number of strands  32  of the tassel tip  30  such that the wires  26  may be used to form the strands. As such, the distal end  24  of the main body  22  includes a hub  36  which is used to band the wires  26  together. Distally from the hub  36 , the wires  26  form the strands  32  which are free to curve and extend proximally to define the atraumatic peaks  34 . Specifically, each strand  32  includes a connecting portion  32   a  connected to the main body  22 , a middle portion  32   b  curving to form the atraumatic peaks  32   b,  and a free end portion  32   c  opposite the connecting portion  32   a.    
         [0027]    As shown in  FIG. 4 , a delivery configuration of the wire guide  20  has been depicted. As discussed in the Background section, the wire guide  20  has particular application in cannulation of the biliary tree during procedures such as ECRP, and thus may be placed at the entrance of the biliary tree in conjunction with an access device. The access device has been depicted as a simple cannula or catheter  40  in  FIG. 4 . The catheter  40  includes an internal passageway  42  that is sized to receive the wire guide  20  and permit translation relative thereto. As such, the wire guide  20  may be translated beyond the open distal end  44  of the catheter  40  whereby the flexible nature of the strands  32  causes them to take their deployed configuration depicted in  FIG. 1 . From the deployed configuration, proximal translation of the wire guide  20  relative to the catheter  40  will cause the catheter&#39;s distal end  44  to impinge upon the inner curvature of the strands  32 , which will again cause them to extend distally as the wire guide  20  is withdrawn into the passageway  42  of the catheter  40 . 
         [0028]    In the delivery configuration depicted in  FIG. 4 , the strands  32  extend distally to define a compact shape that is suitable for being received within the passageway  42  of the catheter  40 . That is, the free end portions  32   c  of the strands  32  are positioned adjacent to the longitudinal axis of the wire guide  20  and main body  22  in the delivery configuration. In the deployed configuration of  FIGS. 1 and 2 , the free end portions  32   c  are spaced radially outwardly from the longitudinal axis of the wire guide  20  and main body  22 . It can also be seen in the figures that the free end portions  32   c  are positioned distally relative to the middle portions  32   b  in the delivery configuration ( FIG. 4 ), and then proximally relative to the middle portions  32   b  in the deployed configuration ( FIG. 2 ). That is, the strands  32  retroflex to define the umbrella shape. 
         [0029]    It will be recognized by those skilled in the art that the main body  22  of the wire guide may take many forms, including multiple wound wires or single wires which may be solid or tubular in form, as well as combinations thereof (see, e.g., U.S. Pat. No. 5,243,996). For example,  FIG. 5  depicts a wire guide  120  having a main body  122  formed of a single solid wire. As with the previous embodiment, the distal end  124  of the main body  122  includes a tassel tip  130  formed by a plurality of strands  132  defining atraumatic peaks  134 . The plurality of strands  132  may be attached to the distal end  124  by many fastening methods including soldering, welding, adhesives or mechanical deformation. As depicted, a hub  138  is used to band or crimp the plurality of strands  132  to the distal end  124  of the main body  122 . 
         [0030]    Similarly,  FIGS. 6 and 7  depict another embodiment of the wire guide  220  which uses a solid wire main body  222 . In this embodiment, the distal end  224  of the main body  222  includes a plurality of channels  238  sized to receive at least a portion of the plurality of strands  232 . As with the previous embodiments, the strands  232  define an atraumatic peak  234  and are connected to the distal end  222  through use of a hub  236  that is used to band the strands  232  to the main body  222 . It can be seen that the strands  232  have a generally circular cross-sectional shape, and thus the channels  238  are circular or semi-circular. Here, a hydrophilic coating  240  has been shown on both the main body  222  and each of the plurality of strands  232 . As noted above, a hydrophilic coating may optionally be used with any embodiment of the present invention. 
         [0031]    Yet another embodiment of the wire guide  320  has been depicted in  FIGS. 9-11 . A solid wire main body  222  is cut, such as by laser or other material removal processes, to unitarily and integrally form the plurality of strands  332 . As best seen in  FIG. 10 , any number of strands  332  may be formed, each having a pie-shaped cross-section. As with the prior embodiments, the strands  332  are structured to form a delivery configuration ( FIG. 9 ) for positioning within the passageway  342  of a delivery catheter  340 . It will also be seen in  FIG. 12  that the distal ends  354  of each of the strands  332 , rather than each having a semi-spherical tip as shown in  FIG. 9 , may together form a semi-spherical or bullet-shaped tip in the delivery configuration. 
         [0032]    In the deployed configuration of  FIG. 11 , the free ends of strands  332  move away from the longitudinal axis and retroflex (i.e. curve and extend proximally) to define the atraumatic peaks  334  and general umbrella shape. It will be recognized that the strands  332  may include grooves  350  or notches  352  or other material deformations to improve the flexibility of the strands  332  and their operability into the deployed configuration of  FIG. 11 . Preferably, an inner edge  333  of each strand  332  is further formed to be curved, such as by a filet, to define the atraumatic peaks  334  of each of the strands  332 . 
         [0033]    The present invention includes a method for performing cannulation of a body lumen employing the wire guides as described above. With reference to  FIGS. 1 ,  4  and  8 , the method generally comprises the steps of coupling a wire guide  20  to an access device  40 . In  FIG. 4 , the wire guide  20  is coupled to the catheter  40  by positioning the wire guide  20 , or at least its distal tassel tip  30 , within the internal passageway  42  of the catheter  40 . The plurality of strands  32  extend distally and are contained within the passageway  42 . The wire guide  20  and access device  40  are advanced as a unit into the bodily lumen, such as the common bile duct depicted in  FIG. 8 , although this step may not be used depending on the particular body structures being cannulized. The wire guide  20  may then be translated distally relative to the access device  40 , whereby the distal movement of the tassel tip  30  causes it to take a deployed configuration such as depicted in  FIGS. 1 and 8 . 
         [0034]    When the bodily lumen is the bile duct  54 , pancreatic duct  60 , or another portion of the biliary tree, the method may further include the steps of placing a duodenoscope  50  into the duodenum  62  of the mammalian patient. Preferably, the duodenoscope  50  is guided until its opening  52  is in close proximity to the papilla of Vater  56  and the sphincter of Oddi  58  which lead to the common bile duct and the pancreatic duct  60 . As such, the advancing step includes passing the wire guide  20  and access device  40  as a unit through the working channel of the duodenoscope  50  and through the sphincter of Oddi  58 . The wire guide  20  may then be advanced to provide deep cannulation of the biliary tree where the tassel tip  30  in the deployed configuration of the wire guide  20  minimizes the potential for trauma to the structures of the biliary tree. Finally, the wire guide  20  may be withdrawn such that the tassel tip  30  again takes its delivery configuration within the access device  40 . 
         [0035]    As indicated in the Background section, newer access devices provide rapid exchange of multiple devices through the provision of exchange ports formed in a distal portion of the access device. For example, this exchange port (or side hole) is placed at about 6 cm from the tip of the catheter or other access device such that only about 6 cm of the wire guide needs to be placed through the internal passageway of the device. Thus, the umbrella shape of the tassel tip  30 , which impinges upon the distal end of the access device when it is withdrawn into its internal passageway, serves as an additional identifier to the physician of the wire guides&#39; location. As such, inadvertent disconnection of the wire guide and access device by withdrawing the wire guide through the exchange port is further minimized. Preferably, each of the strands  32  of the tassel tip  30  extend an axial distance much less than 6 cm so that the tassel tip  30  may be located entirely within working channel of these new access devices. 
         [0036]    Accordingly, it will be recognized by those skilled in the art that the present invention provides a wire guide and method for cannulation using the wire guide which assists in procedures such as ERCP. The wire guide and method minimize the potential for trauma to the ducts in a biliary tree, especially during deep cannulation. At the same time, the wire guide and method reduce the chances of disconnection of the wire guide from newer access devices which while still providing rapid exchange of such devices. 
         [0037]    The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.