Abstract:
A single use, deflectable stylet  10  for use in a catheter includes a deflectable portion  12  of a flexible material. An actuator  14  is attached to the deflectable portion  12,  manipulation of the actuator  14  relative to the deflectable portion  12  causing deflection of the deflectable portion  12.  The stylet  10  further includes a stiffening element  16  with the deflectable portion  12  being associated with a distal region of the stiffening element  16,  the stiffening element  16  being sufficiently stiff in torsion to convert proximal rotation into substantially equivalent distal rotation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority from United States of America Provisional Patent Application No. 60/934,844 filed on Jun. 15, 2007, the contents of which are incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    This invention relates, generally, to catheters and, more particularly, to a single use deflectable stylet for use in a catheter, to a method of fabricating a stylet and to a catheter including the stylet. 
       BACKGROUND 
       [0003]    In heart procedures, a catheter, be it a diagnostic catheter or a therapeutic catheter, is inserted via an introducer into the vasculature of a patient. Normally, the catheter is inserted through the femoral vein of a patient and is steered to a site in a patient&#39;s heart at which a diagnostic and/or therapeutic procedure is to be carried out. At the site, it is necessary to deflect a tip of the catheter to bring electrodes of the catheter into contact with heart wall tissue to effect diagnosis or therapy. 
         [0004]    Thus, a tip of the catheter needs to be deflectable. This is achieved, in the case of the Applicant&#39;s catheter, by inserting a stylet into a lumen of an electrode sheath of the catheter. The electrode sheath is manufactured according to the Applicant&#39;s manufacturing technique and has an unimpeded lumen. This is due to the fact that electrical conductors for electrodes of the electrode sheath are generally embedded in a wall of the electrode sheath. 
         [0005]    The catheter is also manufactured with a low-cost handle. The low-cost handle is achieved by not having electrical conductors or connectors arranged in the catheter. Rather, the electrical conductors pass through the body of the catheter and are connected directly to equipment for communicating with the electrodes of the catheter. It would therefore be beneficial to have a stylet which is also a low-cost item to enable it to be used once only without significantly increasing expenses of an institution using the catheters. 
       SUMMARY 
       [0006]    According to a first aspect of the invention, there is provided a single use, deflectable stylet for use in a catheter, the stylet including 
         [0007]    a deflectable portion of a flexible material; 
         [0008]    an actuator attached to the deflectable portion, manipulation of the actuator relative to the deflectable portion causing deflection of the deflectable portion; and 
         [0009]    a stiffening element with the deflectable portion being associated with a distal region of the stiffening element, the stiffening element being sufficiently stiff in torsion to convert proximal rotation into substantially equivalent distal rotation. 
         [0010]    Preferably, the deflectable portion is of a synthetic plastics material. Further, the stiffening element may be of metal. The metal may be a low cost steel material such as a stainless steel material or it may be aluminium, tungsten, or the like. 
         [0011]    The deflectable portion may be an elongate tubular body member defining a passage. The tubular body member may define an axially extending cutaway region in a wall of the body member to facilitate deflection of a distal part of the body member. 
         [0012]    The cutaway region may subtend an angle of greater than 90° but less than 270°. Typically the cutaway region may subtend an angle of approximately 170° to 190°. 
         [0013]    In this specification, the term “subtend”, unless the context clearly indicates otherwise, is used in the sense of forming or marking the limits of the angle. 
         [0014]    In an embodiment, the cutaway region may be closed off by a cage defined by a plurality of longitudinally spaced, transversely extending slots. 
         [0015]    Instead of, or in addition to, the cutaway region, a plurality of longitudinally spaced, transversely extending slots may be defined in the distal part of the tubular body member to facilitate deflection of the distal part of the body member. 
         [0016]    In one embodiment, the stiffening element may be a tube received in the passage of the tubular body member. In another embodiment, the stiffening element may be a sleeve received over the tubular body member. 
         [0017]    In a further embodiment, the stiffening element may be a tube and the deflectable portion may constitute a tip portion mounted on a distal end of the tube. In this embodiment too, the deflectable portion may comprise an elongate tubular body member defining an axially extending cutaway region in a wall of the body member to facilitate deflection of the distal part of the body member. 
         [0018]    The actuator may be a pull wire extending through the tube and the tubular body member, a distal end of the pull wire being fast with a distal end of the tubular body member. 
         [0019]    In still a further embodiment, the deflectable portion may comprise an elongate, planar element having a mounting formation at its proximal end for mounting to the distal end of the tube. In this embodiment, the actuator may be a pull wire extending through the tube and over the planar element with a distal end of the pull wire being fast with a distal end of the planar element. 
         [0020]    According to a second aspect of the invention, there is provided a single use, deflectable stylet for use in a catheter, the stylet including 
         [0021]    an elongate, tubular body member of a synthetic plastics material, the plastics material being of a type which permits deflection of at least a part of the body member but which is sufficiently stiff in torsion to convert rotation at a proximal end of the body member into substantially equivalent rotation at a distal end of the body member, the body member defining a lumen; 
         [0022]    an axially extending cutaway region defined in a wall of the body member at a distal part of the body member to facilitate deflection of the distal part of the body member, the cutaway region subtending an angle of greater than 90° but less than 270°; and 
         [0023]    an actuator received in the lumen of the body member, a distal end of the actuator being fast with a distal end of the body member and relative displacement between the body member and the actuator causing deflection of the body member about the cutaway region of the body member. 
         [0024]    The body member may be of a thermoplastic material. The thermoplastic material may be a polyetheretherketone (PEEK) material or a polyimide material. 
         [0025]    The cutaway region may be formed with the actuator in position in the lumen of the body member. The cutaway region may be an inwardly crenated region formed in the wall of the body member. The cutaway region may be closed off by a cage comprising a plurality of longitudinally spaced, transversely extending slots. 
         [0026]    The stylet may include a mounting assembly for mounting to a handle body of a catheter. The mounting assembly may include an anchoring element mountable to the handle body and a carrier displaceably arranged relative to the anchoring element, the actuator being mounted fast with one of the anchoring element and the carrier with another component being mounted fast with the other of the carrier and the anchoring element so that relative displacement of the actuator and the other component causes deflection of the deflectable portion. 
         [0027]    Depending on the embodiment, the “other component” may be the tubular body member itself or, where the tubular body member is mounted on a distal end of the stiffening member, the stiffening member. 
         [0028]    According to a third aspect of the invention, there is provided a method of fabricating a deflectable stylet the method including 
         [0029]    providing an elongate tubular body member defining a lumen; 
         [0030]    inserting an actuator into the lumen of the body member; and 
         [0031]    using the actuator as a guide formation, forming an inwardly crenated, axially extending cutaway portion in a wall of the tubular member to form a bend-enhancing region about which the body member is able to deflect. 
         [0032]    The method may include forming the cutaway portion with a subtended angle greater than 90° but less than 270°. 
         [0033]    Further, the method may include securing a distal end of the actuator fast with a distal end of the body member. 
         [0034]    The method may include providing a stiffening member for the stylet. The stiffening member may be a tube and the method may include mounting the tubular body member on a distal end of the tubular member. Instead, the stiffening member may be a tube and the method may include inserting the tube into the lumen of the body member. Still further, the stiffening member may be a tube and the method may include inserting the body member into a passage of the tube. 
         [0035]    According to a fourth aspect of the invention, there is provided a catheter which includes 
         [0036]    a catheter handle having a handle body; 
         [0037]    an electrode sheath extending from a distal end of the handle, the electrode sheath defining a lumen; and 
         [0038]    a single use, deflectable stylet, as described above, received in the lumen of the electrode sheath. 
         [0039]    The catheter may include a deflection control mechanism which is displaceably carried on the handle body, the carrier of the mounting assembly being secured to the displacement control mechanism and the anchoring formation being secured to a proximal end of the handle body. 
         [0040]    A projection control mechanism may be carried on the handle body, the electrode sheath being carried on the projection control mechanism and the projection control mechanism being operable to extend and retract the electrode sheath relative to the stylet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]      FIG. 1  shows a three dimensional view of an embodiment of a single use, deflectable stylet; 
           [0042]      FIG. 2  shows a three dimensional view of a distal part of the stylet of  FIG. 1 ; 
           [0043]      FIG. 3  shows a three dimensional view of another embodiment of a single use, deflectable stylet; 
           [0044]      FIG. 4  shows a three dimensional view of a distal part of the stylet of  FIG. 3 ; 
           [0045]      FIG. 5  shows a three dimensional view of a deflectable part of the stylet of  FIG. 3 ; 
           [0046]      FIG. 6  shows a side view of a part of a further embodiment of a single use, deflectable stylet; 
           [0047]      FIG. 7  shows a sectional end view taken along line VII-VII in  FIG. 6 ; 
           [0048]      FIG. 8  shows a three dimensional view of an embodiment of a catheter including a single use, deflectable stylet; 
           [0049]      FIG. 9  shows a sectional side view of a part of the catheter; and 
           [0050]      FIG. 10  shows a side view of a part of a still a further embodiment of a single use, deflectable stylet. 
       
    
    
     DETAILED DESCRIPTION  
       [0051]    In  FIGS. 1 and 2 , reference numeral  10  generally designates an embodiment of a single use, deflectable stylet  10 . The stylet  10  includes a deflectable portion  12  of a flexible material. An actuator, in the form of a pull wire,  14  is received through the deflectable portion  12 . A distal end  14 . 1  of the pull wire  14  is fast with a distal end  12 . 1  of the deflectable portion  12 . 
         [0052]    The stylet  10  includes a stiffening element in the form of a tube  16 . In this embodiment, the deflectable portion  12 , which comprises an elongate tubular member  18 , is mounted on a distal end of the tube  16 . The tube  16  is of metal such as stainless steel. 
         [0053]    The tubular body member  18  of the deflectable portion  12  is of a thermoplastics material. For example, the tubular body member  12  can be made of a polyetheretherketone (PEEK) plastics or a polyimide plastics material. 
         [0054]    The tubular body member  18  defines a bend-enhancing region  20 . The bend-enhancing region  20  is formed by an inwardly directed, axially extending crenation  22  which is cut into a wall of the tubular body member  18  to a depth sufficient to expose the pull wire  14 . The crenation  22  subtends an angle of greater than 90° but less than 270°. Preferably the crenation  22  subtends an angle slightly less than 180° which, because the deflectable portion  12  is of a plastics material should be sufficient to permit bending in a plane passing through the longitudinal axis of the deflectable portion  12 . 
         [0055]    The stylet  10  further includes a mounting assembly  23 . The mounting assembly  23  comprises an anchoring formation  24  and a mounting member, or carrier,  26  displaceably arranged relative to the anchoring formation  24  to be displaceable in the direction of arrows  28 . 
         [0056]    A proximal end of the pull wire  14  is mounted fast with the anchoring formation  24 . A proximal end of the tube  16  is mounted fast with the carrier  26  so that relative displacement between the carrier  26  and the anchoring formation  24  results in deflection of the deflectable portion  12  in a plane passing through the longitudinal axis of the deflectable portion. More particularly, when the tube  16  is urged distally relative to the anchoring formation  24 , deflection of the deflectable portion  12  occurs about the bend-enhancing region  20 . 
         [0057]    Referring now to  FIGS. 3-5  of the drawings, a second embodiment of a stylet  10  is illustrated. With reference to the previous drawings, like reference numerals refer to like parts unless otherwise specified. In this embodiment, the deflectable portion  12  comprises an elongate strip-like member  30  shown more clearly in  FIGS. 4 and 5  of the drawings. The elongate, strip-like member  30  has a proximal boss formation  32  which attaches to the distal end of the tube  16 . The pull wire  14  passes over a surface of the strip-like element  30  and the distal end  14 . 1  of the pull wire  14  is hooked into the distal end  12 . 1  of the deflectable portion  12  as shown more clearly in  FIG. 4  of the drawings. A notch  34  is defined in an end of the strip-like element  30  to retain the distal end  14 . 1  of the pull wire  14  in position. 
         [0058]    Referring to  FIGS. 6 and 7  of the drawings, yet a further embodiment of a stylet  10  is illustrated. Once again, with reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified. In this embodiment, the stylet  10  is a two-part stylet comprising an elongate tubular body member  36  of a PEEK material or a polyimide material and the pull wire  24 , the tube  16  being omitted. The elongate tubular body member  36  fulfils the function of the tube  16 . Thus, a proximal end of the body member  36  is secured to the carrier  26  of the mounting assembly  23 . In this embodiment, the body member  36  extends the full length of the pull wire  14 , apart from that part of the pull wire within the anchoring formation  24 . 
         [0059]    The elongate tubular body member  36  defines a passage  38  through which the pull wire  14  passes. Once again, a distal end  14 . 1  of the pull wire  14  is fast with a distal end at  12 . 1  of the deflectable portion  12  of the body member  36 . As in the case of the embodiment illustrated in  FIGS. 1 and 2  of the drawings, the deflectable portion  12  of the body member  36  is formed by the bend-enhancing region  20  being in the form of an inwardly directed, axially extending crenation  22 . 
         [0060]    To form the crenation  22  in the case of the embodiment shown in  FIGS. 1 and 2  and in the embodiment shown in  FIGS. 6 and 7 , a tubular member of the plastics material is provided with the passage  38  formed therein. The pull wire  14  is inserted into the passage  38  and is secured to the distal end  12 . 1  of the deflectable portion  12  to be formed in the body member  18  or  36 , as the case may be. 
         [0061]    Once the pull wire  14  has been secured in position, a scalpel or other cutting implement is used to form the crenation  22 . A wall of the body member  18 ,  36  is cut away to the depth of the pull wire  14  and the pull wire  14  is used as a guide in forming the crenation  22 . 
         [0062]    In  FIG. 10 , yet a further embodiment of a stylet  10  is shown and, once again, with reference to the previous embodiments, like reference numerals refer to like parts unless otherwise specified. In this embodiment, instead of the bend enhancing region  20  of the deflectable portion  12  being defined by the crenation, the bend-enhancing region  20  is defined by a cage  37 . The cage  37  comprises a plurality of axially spaced, transverse slots  39  formed in a wall of the body member  36 . 
         [0063]    In the formation of this embodiment, the pull wire  14  is again inserted into the passage  38  and is used as a guide in the cutting of the slots  39  to the required depth. 
         [0064]    Referring to  FIG. 8  of the drawings, an embodiment of a catheter  40  is illustrated. The catheter  40  comprising a handle body  42  having a proximal end  44 . 
         [0065]    The catheter  40  includes an electrode sheath  46  extending from the handle body  42 . A distal end of the electrode sheath carries a plurality of axially spaced electrodes  48 . The distal end of the electrode sheath  46  is deflectable into the position shown in dotted lines using the stylet  10 , as will be described in greater detail below. 
         [0066]    The anchoring formation  24  of the mounting assembly  23  includes an attachment formation in the form of a pair of opposed, radially outwardly extending pins  50  ( FIG. 9 ). The pins  50  engage L-shaped slots at the proximal end  44  of the handle  42 , bayonet fashion. Similarly, the carrier  26  includes securing formations in the form of a pair of opposed, radially outwardly extending pins  52  which engage corresponding slots in a slide  54  ( FIG. 9 ) of the handle body  42  of the catheter  40 . More particularly, the slide  54  is attached to a part of a deflection control mechanism  55 . The deflection control mechanism  55  further includes a deflection control knob  56  axially displaceably arranged on the handle body  42 . The slide  54  is fast with the deflection control knob  56 . Thus, by urging the deflection control knob  56  in the direction of arrow  58 , the tube  16  or the body member  36 , as the case may be, of the stylet  10  is urged distally with respect to the pull wire  14  which is fast with the anchoring formation  24  of the mounting assembly  23 . This causes the deflectable portion  12  of the stylet  10  to bend about the bend-enhancing region  20  resulting in the deflection as shown in dotted lines in  FIG. 8  of the drawings. 
         [0067]    The handle body  42  of the catheter  40  further includes a projection control mechanism  60 . The projection control mechanism  60  comprises a projection control knob  62  arranged distally of the deflection control knob  56 . The electrode sheath  46  is fast with the deflection control mechanism  60 . The deflection control mechanism  60  is used to extend the distal end of the electrode sheath  46  relative to a distal of the stylet  10 . With such an arrangement, hard to reach places in a patient&#39;s heart can be accessed by extending the distal end of the electrode sheath  46  relative to the distal end of the stylet  10 . 
         [0068]    It is a particular advantage of the invention that a low-cost, single use, deflectable stylet  10  is provided. This renders the catheter  40 , in its entirety, disposable as it is made of low-cost materials. Generally, the stylet  10 , in order to be deflectable is made from high cost material such as nitinol. However, the Applicant has determined that, surprisingly, by making the stylet out of suitable plastics materials and metals, instead of the high cost material, adequate deflection of the distal end of the electrode sheath  46  can still be obtained and provide the necessary deflectability. 
         [0069]    It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.