Abstract:
An elongate element, in particular a catheter, has a curved shape imparted to its end by a device comprising razor blades which are mounted on a pivotal linkage mechanism. Upon pressing actuator members against the restoring force of spring elements, the razor blades are constrained by the pivotal linkage mechanism to follow a desired curved path.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of provisional application Ser. No. 60/125,824, filed Apr. 23, 2008. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a shaping device and more particular to a device for cutting an end of an elongate member to impart it to a desired curved shape. In preferred embodiments of the present invention an end of a catheter is shaped. 
     BACKGROUND OF THE INVENTION 
     It is known to manufacture catheters with soft tips. However, in cases where there is a need to trim a catheter to fit an individual patient&#39;s anatomy, such as a PICC (peripherally inserted central catheter), this leaves a relatively hard and untrimmed tip which is traumatic for the patient during insertion of the catheter. PICC catheters are used for the intravenous administration of nutrient fluids, chemotherapeutic agents and other drugs for therapy. 
     Aspects of the present invention seek to reduce or overcome the above problem. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a device for imparting a curved shape to an end of an elongate element, the device comprising a support member and at least one cutting member mounted on the support member to move relatively thereto, the cutting member being connected to the support member by means of a pivotal linkage mechanism, the pivotal linkage mechanism constraining the cutting member to move along a path to define said curved shape as it moves, and at least one actuating member arranged to cause said movement of the cutting member. 
     According to a second aspect of the present invention, there is provided a device for cutting a desired curved shape in the end of a catheter comprising a housing, a first member having a first, cutting end and a second end, a second cutting member having a first, cutting end and a second end, a pivotal mechanism located in said housing and comprising first, second, third and fourth links, said first and second links being pivotally connected by a first pivot element, said first pivot element being fixed to said housing, said third and fourth links being pivotally connected by a second pivot element, said second pivot element being slidably mounted in said housing, said first link being pivotally connected by a third pivot element to said first end of said first cutting member, said third link being pivotally connected by a fourth pivot element to said second end of said first cutting member, said second link being pivotally connected by a fifth pivot element to said first end of said second cutting member, and said fourth link being pivotally connected by a sixth pivot element to said second end of said second cutting member, a first actuating member arranged to slide relative to said housing from a first position to a second position, said first actuating member engaging said first link to cause movement of said first cutting member to impart said desired curved shape to the catheter, a second actuating member arranged to slide relative to said housing from a first position to a second position, said second actuating member engaging said second link to cause movement of said second cutting member to impart said desired curved shape to the catheter, a first resilient member for returning said first actuating member from its second position to its first position, and a second resilient member for returning said second actuating member from its second position to its first position. 
     According to a third aspect of the present invention, there is provided a catheter having a longitudinal axis and an end which is of curved shape viewed in directions perpendicular to the longitudinal axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which: 
         FIG. 1  is a sectional view of an embodiment of a shaping device in an initial disposition and showing an inserted catheter to be trimmed; 
         FIG. 2  is similar sectional view of the device of  FIG. 1  in an operating disposition thereof; 
         FIG. 3  is a similar sectional view of the deice of  FIG. 1  in an end disposition thereof; 
         FIG. 4  is an external view of the device of  FIG. 1 , showing the housing thereof; 
         FIG. 5  is a perspective partial view of the operating mechanism of the device of  FIG. 1  in its initial disposition and with an inserted catheter; 
         FIG. 6  is a view similar to  FIG. 5  but without the catheter; 
         FIG. 7  is a view similar to  FIGS. 5 and 6  of the device of  FIG. 1  in its end position and showing the housing; and 
         FIG. 8  shows the end of a catheter cut by the device. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings,  FIG. 1  shows a sectional view of a cutting device  10  for shaping the end of a catheter  20 , typically of a plastics material. The device has a housing  30 , shown only in section in  FIG. 1 , having open ends  32 ,  33  ( FIG. 4 ) through which the catheter end  21  to be trimmed is passed. Device  10  comprises two razors  12 , 14  having respective cutting edges  16 ,  18 . The razors have blunt edges at their ends opposite to cutting edges  16 ,  18 . The razors are interconnected by a linkage mechanism  40  comprising four links  4144  connected to each other and to the razors  12 ,  14  by six pivotal connections at pivot pins  51 - 56 . 
     Links  41  and  42  are interconnected by pivot pin  51  so as to pivot relatively to each other. The ends of pivot pin  51  are fixedly attached to housing  30 . Links  43  and  44  are interconnected by pivot pin  52  so as to pivot relatively to each other. The ends of pivot pin  52  are attached to respective bearings  58  which slide in respective slots  59  arranged in the top  35  and bottom  36  of housing  30 . Thus pivot pin  52  is constrained to move in a direction parallel to the length of the catheter  20 . 
     The other ends of links  41  and  42  are respectively connected by pivot pins  53 ,  55  to razors  12 ,  14  adjacent the sharp edges thereof. The other ends of links  43  and  44  are respectively connected by pivot pins  54 ,  56  to razors  12 ,  14  adjacent the blunt edges thereof. A coil spring  61  is connected between link  41  and bearing  58 . A coil spring  63  is connected between link  42  and bearing  58 . In the initial disposition of the device shown in  FIG. 1 , the springs  61  and  63  are relatively relaxed. 
     As can be seen from  FIGS. 5 to 7 , links  41 ,  42  are in the form of plate members with ends  411 ,  412  and  421 ,  422  extending above and below the rest of the operating mechanism. The sides  38 ,  39  of housing  30  have apertures therein for slidably retaining respective actuator members  71 ,  72 . Actuator member  71  comprises upper and lower projecting fingers  73 ,  74  which respectively engage the upper and lower ends  421  and  422  of link  42 . In mirror image fashion, actuator member  72  comprises upper and lower projection fingers  76 ,  77  which respectively engage the upper and lower ends  411 ,  412  of link  41 . 
     The lengths of links  4144  and the position of pivot pins  51  to  56  are selected so that the razor edges  16 ,  18  can move to sever the end of  20  leaving an end of a desired curved shape or contour. This is achieved as follows. 
     Catheter  20  is first inserted through the open ends  32 ,  33  of housing  30  until the desired cutting location along the length of the catheter lies within the housing. Actuator members  71 ,  72  are then manually urged towards each other so that straight cutting edges  16 ,  18  engage the catheter  20  at the precise location where it is desired to commence cutting. It will be appreciated that the members  71 ,  72  act in substantially mirror-symmetrical fashion. As the actuator members are pushed closer together, cutting commences and the material of the wall of the catheter is cut as the edges  16 ,  18  move from the relative disposition in  FIG. 1  to that shown in  FIG. 2 . Initially each blade edge cuts material from a single region of the catheter wall, but as cutting continues, each blade subsequently cuts the wall at two spaced locations (above and below the plane of the paper in  FIGS. 1 and 2 ). There thus results a cut which is curved in three dimensions. During the cutting movement, the cutting edges  16 ,  18  cover the path indicated by line  19  in  FIG. 3 , which corresponds to the shape of the cut edge in the plane of the drawing. 
     During the movement of the actuator members, pivot pin  52  on bearing  58  is able to slide parallel to the length of the catheter. Also, pivot pins  53 ,  54  are moved towards each other so that springs  61 ,  63  are compressed between links  41 ,  42  respectively and bearing  48 . 
     Finally, actuator members  71 ,  72  reach their closest portion,  FIG. 3 , in which cutting edges  16 ,  18  meet and the cutting operation is complete. The actuator members are then released and the springs  61 ,  63  push links  41 ,  42  so that the operating mechanism returns to the disposition shown in  FIG. 1  and the cut catheter can be removed from the housing. 
     The resulting saddleback shape of the end of the catheter  20  is shown in  FIG. 8 . 
     An advantage of the above-described device is that it enables a non-traumatic catheter tip to be quickly and easily produced. This is particularly advantageous should the need arise, perhaps unexpectedly during a surgical operation. If it is found that a catheter has been cut to the wrong length, it can quickly be cut again. 
     It will further be appreciated that the cutting procedure produces a trauma-free profile on both sides of the cut. Thus both parts of the cut catheter could be used in medical procedures. 
     Numerous modifications can be made to the above-described device. 
     For example, coil springs corresponding to coil springs  61 ,  63  can also be provided at the bottom of housing  30 . The springs could be configured to be tensioned instead of compressed by operation of the device, before returning to the initial disposition. The springs may be replaced by other suitable resilient members. Alternatively, no resilient members are provided in which case the cutting members are returned manually by the user to their initial disposition. 
     An arrangement comprising a bearing  58  and a slot  59  may be provided only at the top or bottom of the housing  30  instead of at both locations. Pivot pin  51  may be arranged to slide relative to the housing. 
     Although relatively simple actuator members  71 ,  72  in the form of push buttons are described in connection with above embodiment, these may be modified as desired. For example they may have handles and/or their own further linkage mechanism to enable a higher force to be exerted on the cutting edges, e.g. for catheters of relatively hard material. Instead of being generally cuboidal, housing  30  can be cylindrical. Alternatively, housing  30  can be omitted, in which case a framework is provided for mounting at least pivot pins  51  and  52 . The framework can include means for guiding the members  71 ,  72 . Alternatively the actuator members may have no guiding means. In a further modification, the actuator member can be omitted and the ends  411  and/or  412  are directly moved manually. The lengths and points of connection of the various links, and even the number of links, may be varied to provide a desired cut shape. For example, it may be desired to produce a shape which has a greater curvature in some regions and a lesser curvature or no curvature in other regions. The shape of the cutting edges  16 ,  18  may also be selected as desired. 
     Additional means (not shown) may be provided for retaining an inserted catheter within the housing or framework before cutting commences. 
     In another modification, a device with only a single blade is provided. First one half of the total cut is made, the catheter is then rotated around its axis by 180° and then the cut is completed by severing the remaining half of the catheter. Although such a device is not so quick and convenient s the above-described device, it requires fewer components and is thus cheaper. 
     If the catheter is of a relatively soft plastic material, a mandrel (e.g. of steel) may be placed inside the catheter to stiffen it adjacent the region to be cut. Curved razor edges can be used here to avoid contact with the internal mandrel. 
     The catheter to be cut may have a circular, elliptical or other cross-sectional shape. 
     The catheter to be cut may have two or more lumens. By rotating the catheter during the cutting process, different tip configurations can be obtained; this offers possibilities for reducing vessel trauma and thrombosis problems. 
     The device may be used to cut any elongate object, whether of hollow or solid cross-sectional shape, to any desired end profile. 
     The features of the various modifications may be combined or substituted as desired. 
     What has been described and illustrated herein is a preferred embodiment of the invention along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant in their broadest reasonable sense unless otherwise indicated.