fig1 illustrates the typical anatomical position of a flexible endoscope when used to cannulate the papilla of vater . a flexible endoscope 100 , in this case a duodenoscope , is passed through the patient &# 39 ; s mouth ( not shown ), the esophagus 102 , the stomach 104 , and into the first part of the duodenum 106 . the endoscopist then maneuvers a distal end 118 of the endoscope so that it is positioned adjacent to the papilla of vater 110 . fig1 also illustrates a portion of the pancreatobiliary system . the pancreatic duct 112 joins the common bile duct 108 coming from the gallbladder 114 and liver ( not shown ). secretions from the liver and pancreas are collected by this ductal system and empty into the duodenum via a small orifice in the papilla of vater 110 . one of the objectives of the medical procedure known as ercp ( endoscopic retrograde cholangiopancreatography ) is to cannulate the papilla of vater with a thin flexible cannula 116 through which x - ray contrast media is injected to enable the pancreatobiliary ductal system to be seen radiographically via a fluoroscope . fig2 shows an enlarged view of the distal end of the endoscope and the cannulation procedure . the distal end 118 of the endoscope 100 with side - viewing optics is positioned in the duodenum 106 with its tip close to the papilla of vater 110 . the operator can move an elevator 200 contained in the endoscope tip up and down relative to the endoscope by means of an elevator control wire 206 which runs up the shaft of the endoscope from the elevator to the control handle of the endoscope ( not shown ). the operator observes the position of the catheter relative to the papilla of vater as he / she manipulates the position of the endoscope itself and the cannula passing through the endoscope . the line of sight ( direction of view ) 208 of the endoscope is approximately perpendicular to the axis of the endoscope to enable it to optimally visualize the papilla of vater en face . with difficult but careful manipulation of the endoscope and the cannula , the operator is generally able to insert the tip of the ercp cannula 116 through the orifice of the papilla , and into the lumen 202 of the ductal system . fig3 illustrates a problem that is commonly encountered when a standard plastic ercp cannula 116 is inserted into the ductal orifice 204 of the papilla of vater 110 at an angle with the duct 202 . pushing the tip of the cannula against the papilla will often embed it in the tissue rather than allowing it to slide successfully into the duct . fig4 a illustrates the advantage of a first embodiment . the distal end of the cannulation device 402 is composed of a series of segments 400 which allow it to flex and align with the axis of the ductal lumen 202 . as fig4 b illustrates , once the most distal few segments enter the lumen , they guide the rest of the cannulation device 402 into the duct . the flexibility of the segmented tip prevents it from embedding itself in the wall of the tissue , and enables it to preferentially slide into the duct itself . fig5 is a cross - sectional view of the tip of the first embodiment shown in fig4 a and 4b . the shaft of the cannulation device 402 is composed of two main components . an outer component is a sheath 500 composed of either plastic tubing or wound wire ( coil wire ) that creates the outer surface of the device . inside this sheath is a control wire 502 that runs throughout the length of the sheath &# 39 ; s lumen 506 and terminates by running through the center of a series of segmental elements 400 . in the embodiment illustrated in fig5 , these segmental elements take the form of spherical beads each of which has a central lumen 508 through which the flexible control wire 502 passes . the dimension of the control wire and the dimension of the holes within the beads are such that the beads are loosely strung over the control wire . the control wire is firmly affixed to the most distal of the beads at a fixation point 504 . depending upon the materials selected for the control wire and the beads , the method of fixation may be soldering , an epoxy adhesive , thermoplastic welding , etc . while fig5 illustrates an embodiment with five beads , any number of segments could be used , depending upon the desired tip characteristics and the particular intended application for the device . fig6 a & amp ; 6b illustrate how the shape and flexibility of the segmented tip will change depending upon the position and tension placed on the control wire . since the distal - most bead is firmly affixed to the flexible control wire , and since extension of the control wire from the tip of the shaft 602 will cause the beads to separate — releasing the tension in the control wire and extending the beads will cause the beaded tip to become increasingly more flexible . the final rigidity of the beaded section will be largely determined by the inherent flexibility of the control wire 502 itself . on the other hand , if tension is put on the control wire to pull the beads against one another and against the distal end 602 of the shaft 402 , the beaded portion of the cannulation device will become increasingly more rigid and less easily deflected , as illustrated in fig6 b . by varying the amount of tension placed on the control wire , the tip of the cannulation device can vary progressively from being very floppy to becoming very rigid . this ability to immediately change the flexibility of the tip of the device over a wide range is part of the utility of the apparatus . fig7 illustrates the components of a complete cannulation device of the first embodiment . the shaft of the device 402 has sufficient length to reach the target anatomy of the patient . in the ercp application illustrated in fig1 , the shaft of the device must be at least as long as the channel of the endoscope through which it passes , plus some additional length so that it can be handled conveniently . in other applications the catheter may be inserted into the body directly without passing through another medical instrument , may be inserted through an access cannula ( e . g ., through a vascular catheter ), or other appropriate means of entry into the body . the overall length of the device must be appropriate for its application . likewise , the overall diameter of the shaft 402 and the diameter of the segmental elements 400 at its tip are made appropriate for the diameter of the duct or vessel that the device is intended to cannulate . the segmental elements 400 at the distal tip of the device are loosely strung over a flexible control wire 502 that runs through the lumen of the shaft to a handle 700 operated by the user . the diameter of the control wire and the materials of its construction are chosen to match the characteristics of the device with its intended application . the control wire may be composed of metal which would cause it to have more spring when in a relaxed ( non - tensioned state ), or be composed of a polymer which would cause it to be more floppy when relaxed , or composed of other material ( s ) exhibiting characteristics desirable for the particular intended medical application . the level of tension in the control wire 502 , and thereby the degree of rigidity in the tip of the device , is controlled by the operator by moving the slider 704 relative to the handle 700 . the handle has no stops or adjustments , allowing the operator to fully control the amount of tension placed on the handle , and thereby the degree of rigidity in the segmented tip . the embodiment illustrated in fig7 also contains an injection port 702 on the handle of the device , through which the operator can inject fluids ( such as x - ray contrast media ) through the lumen of the catheter 402 , which fluid then exits the distal end of the catheter 602 . fig8 illustrates that to allow fluid injected into the lumen 506 of the sheath 500 to exit from the tip 602 of the sheath , the control wire 502 must be extended to create a gap between the most proximal of the segmental elements 400 and the tip of the sheath 602 . this will allow fluid to flow 800 from the cannulation device into the duct in which it is residing . fig9 illustrates a second embodiment of an appropriate handle 700 for the cannulation device . similar to the previous embodiment , the control wire 502 is connected to the slider 704 . movement of the slider puts more or less tension in the control wire , thereby changing the flexibility of the segmented tip ( not shown ). however , in this embodiment , a stopper 900 is affixed to the control wire 502 as illustrated in fig9 a . this stopper limits the movement of the control wire . a proximal stop nut 902 limits movement of the control wire as the slider on the handle is “ closed ”, thereby limiting the maximum amount of tension placed on the segmental elements and the maximum rigidity of this section of the cannulation device . a distal stop nut 904 conversely limits the amount that the handle can be “ opened ”, thereby limiting the distance that the control wire can be extended from the tip of the cannula . in the embodiment illustrated in fig9 , the position of these maximum and minimum settings can be changed by the operator by changing the position of the threaded stop nuts on the handle . furthermore , each stop nut has a cutout 906 which allows the stopper 900 to bypass the stop nut when the stop nut is rotated into the “ free ” position , as illustrated in fig9 b . this feature allows the operator to quickly put the handle into a configuration in which the maximum and minimum limits of the control wire movement are overridden . when the stop nuts are put into the “ free ” configuration , the slider 704 can move back and forth freely without the stopper 900 encountering the stop nuts ( 902 & amp ; 904 ). fig1 illustrates a third embodiment of the handle 700 of the cannulation device of the present invention . as in the handle illustrated in fig9 , movement of the slider 704 moves the control wire and changes the rigidity of the segmented tip . however , movement of the control wire is limited by a stopper 900 affixed to the control wire . this stopper limits the movement of the control wire to the positions set by the proximal 902 and distal 904 stop nuts . the position of these stop nuts can be changed by the operator by rotating them over the threaded shaft on which they are mounted . furthermore , each of the stop nuts has a cutout 906 in it . the operator can quickly override the limits of the stop nuts by rotating the nuts to place them in a configuration whereby the stopper 900 passes through the cutouts 906 and is no longer limited by the stop nuts . the embodiment illustrated in fig1 also contains an injection port 702 through which fluids may be injected into the cannulation device . unlike the handles illustrated in fig7 & amp ; 10 which require that the operator constantly operate and monitor the tension in the control wire , a fourth embodiment of the handle which is illustrated in fig1 will apply a constant , and in this embodiment , an adjustable amount of tension in the control wire . the handle 150 is attached to the proximal end of the shaft 402 of the cannulation device . the proximal end of the control wire 502 running through the length of the shaft is rotatably fixed 154 to a stiffness adjustment nut 156 threaded 160 on the shaft 158 of the handle . as this adjustment nut 156 is screwed away from the handle 150 it pulls on the control wire 502 with an increasing amount of tension , making the segmented tip of the device more rigid . when the adjustment nut is screwed in the opposite direction it releases the tension in the control wire , reducing the rigidity of the segmented tip . a spring 152 on the handle puts pressure on the stiffness adjustment nut 156 thereby maintaining it in the position set by the operator . this embodiment of the handle allows the operator to set a constant amount of tension in the control wire , and thus a constant degree of rigidity in the segmented tip without the need to constantly hold ( or operate ) the handle . the degree of rigidity in the segmented tip can be changed by the operator as needed during the procedure . fig1 illustrates a fifth embodiment of the handle of the cannulation device . in this embodiment the control wire 502 is connected to a slider 704 on the handle 700 . a spring 152 places a constant , preset amount of force on the slider , and thereby a constant , preset amount of tension in the control wire 502 which in turn produces a constant preset degree of rigidity in the segmented tip . this preset amount of rigidity in the tip of the device can be adjusted by changing the position of the stiffness adjustment nut 156 . in this embodiment , the operator has the ability to further enhance the rigidity of the tip of the device by “ closing ” the handle by pulling the slider 704 towards the thumb ring 176 . this action increases the tension in the control wire , stiffening the tip . in a similar manner , the operator can “ open ” the handle by moving the slider 704 away from the thumb ring 176 . this action compresses the spring 152 , relaxing the tension in the control wire and making the segmented tip more flexible . although several embodiments for the handle of the cannulation device have been illustrated , one of ordinary skill in the art , in light of this teaching , can generate additional embodiments and modifications without departing from the spirit or exceeding the scope of the claimed invention . fig1 illustrates that the segmental elements 400 at the distal tip of the catheter 402 can likewise have several embodiments . as illustrated in fig1 a , in a first embodiment of the tip , the segmental elements have an approximate spherical shape . alternatively , as illustrated in fig1 b , the segmental elements may have an approximate cylindrical outermost surface with ends that allow them to flex with respect to each other . as fig1 c illustrates , the segmental elements may have other alternative shapes that facilitate smooth entry in ductal orifices and smooth passage along the wall of the duct or the vessel it is in . as fig1 d & amp ; 13e illustrate , there is a benefit to tapering the size of the individual segmental elements . the small diameter of the distal - most element facilitates its entry into small orifices , while the increasing diameter of subsequent elements guides the larger diameter catheter into the ductal system . in addition to tapering the size of the segmental elements , the cannula sheath 402 may have a tapered distal tip 178 , as illustrated in fig1 f . the present invention does not specify or limit the number of segmental elements used in the cannulation device . the device may only two ( fig1 g ) to improve the control that the operator has over the tip of the device , or may have many elements to increase the radius of tip deflection depending on the specific application for which the cannula is designed . the tips of prior art cannulas 116 also have various configurations . some are simply blunt tipped 186 tubes , as illustrated in fig1 a . others have a tapered 182 distal end to improve entry into small diameter orifices , as illustrated in fig1 b . some have a rounded 184 “ nose ”, as illustrated in fig1 c . another embodiment of the present invention , as illustrated by fig1 d , is to limit the number of segmental elements to one , and to configure the device such that when the element 400 is pulled against the sheath 500 by the control wire 502 running through its lumen , the combined profile of the element 400 and the distal tip of the cannula 180 create a surface that cannulates more easily than the open ended cannulas of prior art . the reason for this improved cannulation ability is that prior art cannulas are of necessity blunt at the very tip due to their open lumen . however , when the element of the current invention fills this open lumen with a rounded shape , it facilitates passage of the cannula tip over tissue and facilitates its entry into ductal orifices . as fig1 e illustrates , after cannulation , the control wire 502 is advanced moving the element 400 away from the distal end 180 of the catheter , allowing fluid to flow from the lumen 506 of the catheter out of the distal tip . this flow of fluid 800 allows the cannulation device to be used as a catheter following ductal cannulation . as fig1 f , fig1 g and fig1 h illustrate , the shape of the single element 400 may have many embodiments , including a proximal surface 188 that serves to position the element 400 in the center of the catheter &# 39 ; s distal end 180 . fig1 illustrates the components of one embodiment of a cannulation device with a single element at its distal tip . the element 400 is affixed to the distal end of a control wire 502 that runs through the catheter sheath 500 , through a control body 254 , and to a proximal handle 252 . as the handle 252 is moved towards and away from the control body 254 , it moves the distal element 400 away from and towards the distal end of the sheath , respectively . an injection port 702 on the control body allows the injection of fluid down the open lumen of the sheath , exiting at its distal end . a fluid seal 250 at the proximal end of the control body prevents this fluid from leaking out around the proximal end of the control wire . while the previous discussion has focused on the ability of the apparatus to enter a ductal orifice , the same is also useful in guiding passage of a cannula or guidewire through ductal systems such the fallopian tubes , the urinary tract , biliary and pancreatic ducts , blood vessels and similar lumened anatomy . as fig1 illustrates , the apparatus disclosed herein are useful for guiding the tip of commonly used guidewires and catheters into selected bifurcating tracts 192 of these ductal and vessel systems 190 . while there has been shown and described what is considered to be preferred embodiments of the invention , it will , of course , be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention . it is therefore intended that the invention be not limited to the exact forms described and illustrated , but should be constructed to cover all modifications that may fall within the scope of the appended claims .
a cannulation device is provided that includes : an elongated flexible sheath having a lumen and a distal end ; a segmented tip including one or more segmental elements disposed at the distal end ; a control member disposed in the lumen and fixed to a distal most segmental element of the one or more segmental elements ; and an actuator for selectively tensioning and relaxing the control member to decrease and increase , respectively , a flexibility of the segmented tip .