Abstract:
A deflectable stylet system optimized for use in conjunction with a lead of the type having a fixation helix that is screwed into body tissue by rotation of the lead&#39;s connector pin is disclosed. The system includes an attachment that is rotatable and longitudinally slidable with respect to the handle of a deflectable stylet. A lead coupled to the attachment may be moved longitudinally with respect to a stylet to account for slight variances in the lead length. In one embodiment, the attachment couples to the lead via a pushbutton mechanism that can be locked to the lead using one hand. The attachment may be rotated to thereby rotate the lead connector. This allows for retraction and extension of a retractable fixation helix, and for further attachment or detachment of a fixation helix to adjacent tissue. In one embodiment, the attachment may be longitudinally rigidly positioned in predetermined locations with respect to the handle. According to another aspect of the system, a deflection device is coupled to the handle to facilitate deflection of the stylet. In one embodiment, this deflection device may be rotatably and/or slidably activated to accomplish the stylet deflection. The system allows a user to adjust lead length with respect to the stylet length, and to further perform stylet deflection and lead rotation all with one hand.

Description:
CROSS REFERENCE TO PRIORITY APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 10/844,746, filed May 13, 2004; which is a divisional of U.S. patent application Ser. No. 09/659,797, filed Sep. 12, 2000; both of which are herein incorporated by reference in their entirety. 
     
    
     CROSS REFERENCE TO COMMONLY-ASSIGNED PATENTS 
       [0002]    Reference is made to commonly-assigned U.S. Pat. No. 6,059,482, filed May 29, 1998, by Baumann; and to commonly-assigned U.S. Pat. No. 6,027,462 issued to Greene et al, which have related subject matter. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates generally to implantable leads and catheters and more particularly to mechanisms for deflecting implantable leads and catheters to assist in guiding them through the vascular system. 
         [0004]    Over the years, quite a number of mechanisms have been disclosed and employed to deflect catheters and implantable leads. These have taken the form of deflectable guidewires and deflectable stylets, typically operable from the proximal end of the lead or catheter, which controllably impart a curve to the distal portion of the catheter. One group of devices comprise deflectable stylets or guidewires which employ a straight, tubular outer member with a curved inner member, the inner and outer members movable relative to one another. Examples of this type of deflection mechanism are disclosed in U.S. Pat. No. 4,136,703 issued to Wittkampf and U.S. Pat. No. 5,728,148 issued to Bostrom et al. Alternatively, deflection devices employing a curved outer member and a relatively straight inner member are also known to the art, as disclosed in U.S. Pat. No. 4,676,249 issued to Arenas and U.S. Pat. No. 5,040,543 issued to Badera et al. In devices of both types, the relative position of the inner member with respect to the outer member determines the degree to which the curved member (inner or outer) is allowed to display its preset curvature. 
         [0005]    A more commonly employed approach to providing controllable deflection employs a generally straight outer member and a tension or push wire located within the outer member that, upon advancement or retraction, causes the outer member to bend. Examples of such deflection mechanisms can be found in U.S. Pat. No. 4,815,478 issued to Buchbinder et al., and U.S. Pat. No. 4,940,062 issued to Hampton et al. Particularly in the context of deflectable stylets intended for use in conjunction with implantable medical leads such as pacing and cardioversion leads, steerable stylets employing this third type of deflection mechanism are disclosed in U.S. Pat. No. 5,662,119 issued to Brennan et al., U.S. Pat. No. 5,170,787 issued to Lindegren, and U.S. Pat. No. 5,327,906 issued to Fideler et al, all of which are incorporated herein by reference in their entireties. 
         [0006]    Additional deflectable stylet designs are disclosed in the above-cited Bauman and Greene et al applications. In these designs, the handle for the stylet is provided with a rotatable knob which, like in the above-cited Fideler patent, is employed to curve and straighten the stylet. This knob is provided with a distally facing recess at its distal end. The connector assembly of the lead is located in this distally facing recess. 
         [0007]    In conjunction with the use of deflectable stylets to implant leads having screw-in fixation mechanisms which require rotation of the connector pin to screw the fixation mechanism into body tissue, it is also known to employ a spinner ball or clamp to rotate the connector pin, as described in the Pacesetter Locator Steerable Stylet User Manual for the Pacesetter Model 4036 Steerable Stylet. The spinner ball, as described, however, does not allow compensation for variations in lead length or allow for ready adjustment of the position of the stylet within the lead body. For example, the spinner ball mechanism must be disconnected from the handle to allow for retraction of the stylet tip within the lead to reduce the stiffness at the lead tip. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed toward providing a deflectable stylet system particularly optimized for use in conjunction with a lead of the type having a fixation helix, in which the fixation helix is screwed into body tissue by rotation of the connector pin of the lead. In particular, the invention is intended to provide a deflectable stylet system that allows for differences in length from lead to lead and also provides an easy mechanism for adjusting the position of the stylet within the lead body. 
         [0009]    The present invention accomplishes the above results by means of an attachment to the stylet handle which includes an affixation device that may be connected to the connector pin of the lead. In one embodiment, the affixation device may be a threaded device such as a screw. In another embodiment, the affixation device is a pushbutton clevis having an unlocked position for receiving the lead, and a locked position for rigidly coupling the lead to the attachment. 
         [0010]    When the attachment is coupled to the lead, the attachment may be rotated to screw the fixation helix into body tissue, configured such that the knob and the lead to which it is attached may readily be moved longitudinally relative to the remainder of the deflectable stylet handle. In a preferred embodiment, the attachment includes a knob with a recess at its distal end for engaging the connector pin of a lead and an elongated tubular extension at its proximal end, slidably inserted into a corresponding distally facing recess in a deflectable stylet handle. In a more preferred embodiment, the distally facing recess in the stylet handle is formed within the spinner or knob of a deflectable stylet handle generally as disclosed in the above cited Greene et al application. The proximally directed extension on the attachment&#39;s knob allows for it to be moved longitudinally relative to the stylet handle, in turn allowing for longitudinal movement of the lead relative to the deflectable stylet. 
         [0011]    In one preferred embodiment, the deflectable stylet assembly is also provided with a tubular pin, mounted around the proximal portion of the flexible stylet and mounted in fixed longitudinal relationship with the stylet handle. This tubular pin may engage the interior of the proximally directed tubular extension of the attachment, providing for an additional mechanism to allow longitudinal movement of the attachment knob relative to the deflectable stylet handle, while retaining appropriate alignment of the attachment knob and stylet handle to allow for rotation of the attachment knob. In some embodiments, a bushing may be provided within the attachment to facilitate the free rotation of the attachment around the tubular pin. The attachment may be slip-fit to the tubular pin in a manner that provides for controlled longitudinal repositioning of the attachment with respect to the stylet assembly. The attachment may also be adapted to rigidly couple to the tubular pin at predetermined positions on the pin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a plan view of a prior art deflectable stylet similar to that used in conjunction with the present invention. 
           [0013]      FIG. 2  is a plan view of the deflectable stylet of  FIG. 1  shown inserted into an implantable cardiac pacing lead. 
           [0014]      FIG. 3  is a cut-away view through a partially disassembled control handle of one embodiment of the deflectable stylet illustrated in  FIG. 1 . 
           [0015]      FIGS. 4 and 5  are cut-away views through the distal portion of the handle of a deflectable stylet according to the present invention, with a slip-on attachment according to the present invention and a lead with an advanceable fixation helix in place. 
           [0016]      FIG. 6  is a cut-away view of another embodiment of the handle assembly and the attachment. 
           [0017]      FIG. 7  is a perspective diagram of the embodiment of the attachment illustrated in  FIG. 6 , and further includes the pushbutton clevis mechanism. 
           [0018]      FIG. 8  is a cross-sectional view of the distal end of the attachment illustrating the pushbutton in an unlocked position. 
           [0019]      FIG. 9  is a cross-sectional view of the distal end of the attachment illustrating the pushbutton in a locked position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]      FIG. 1  illustrates a plan view of a prior art deflectable stylet, similar to that employed in conjunction with the present invention. The deflectable stylet  16  is provided with a control handle assembly  10  provided with a handle  12  and a deflection control which takes the form of a spinner or knob  14 , mounted rotatably and slidably with respect to the handle portion  12 . The handle  12  is provided with indentations at its proximal end, as is the spinner or knob  14  to assist the physician in maintaining a grip. Ribbing, knurling or other texturing could of course be substituted. The deflectable stylet  16  exits from a distal recess  15 , within spinner or knob  14 . The rotation of spinner or knob  14  causes deflection of the distal portion of stylet  16  to a curved configuration as illustrated at  16 A. 
         [0021]    Deflectable stylet  16  may take the form of any known deflectable stylet employing an outer tubular member and an inner tension wire which, when it applies tension to the distal tip of deflectable stylet  16 , causes the tip of the stylet to curve. Appropriate designs for the deflectable stylet  16  include those described in the Brennen et al, Lindegren and Fideler patents and Bauman and Greene et al. applications discussed above. Alternatively, deflectable stylet  16  may be replaced by a deflectable guidewire, for example, as disclosed in the above-cited Buchbinder patent, also incorporated herein by reference in its entirety. In all of these various guidewires and stylets, the basic structure of the deflectable stylet or guidewire consists of a generally straight element, and an internal tension wire coupled to the distal portion of this straight element, and arranged such that upon application of tension to the internal tension wire, the distal portion of the guidewire or stylet exhibits a curved configuration as illustrated in broken outline at  16 A. 
         [0022]      FIG. 2  is a plan view of the deflectable stylet of  FIG. 1  inserted into a screw-in cardiac pacing lead  20  of a type not requiring rotation of the connector pin relative to the lead body. Cardiac pacing lead  20  comprises an elongated insulated lead body  24  carrying an internal conductor and provided with a connector assembly  18  located at its proximal end, which typically carries a connector pin as is typical of cardiac pacing leads. For example, the distal portion of the connector assembly  18  may correspond to the IS-1 connector standard as disclosed in U.S. Pat. No. 4,922,607 issued to Doan et al., also incorporated herein by reference in its entirety. However, other connector configurations, such as disclosed in U.S. Pat. No. 4,488,561 issued to Doring or U.S. Pat. No. 4,572,605 issued to Hess et al., both also incorporated herein by reference in their entireties, may also be employed. At the distal end of pacing lead  20  is located a fixed helical electrode  22 , such as that disclosed in U.S. Pat. No. 5,473,812 issued to Morris et al. and incorporated herein by reference in its entirety, which is screwed into heart tissue in order to stimulate the heart. 
         [0023]    As illustrated, the connector assembly  18  of the lead  20  is inserted into the distal facing opening  15  within spinner or knob  14 . The spinner or knob  14  is free to rotate with respect to connector assembly  18 . Thus, rotation of the spinner knob does not rotate the connector pin of the lead or the lead body itself. However, rotation of the lead body with respect to the deflectable stylet is typically required in order to screw a helical electrode  22  located at the distal end of the lead into heart tissue. Therefore, an alternative mechanism is needed to accomplish the affixation of the helical electrode. This mechanism will be described in detail below. 
         [0024]    The above discussion relates to the use of a deflectable stylet in conjunction with an implantable lead. The stylet may further be used with any type of steerable catheter, including an ablation catheter. 
         [0025]      FIG. 3  is a cut-away view of a partially disassembled handle assembly  10 , as illustrated in the figures discussed above. The handle  12  is fabricated of two molded plastic parts, joined together essentially along a longitudinal line extending the length of the handle. One of the two handle halves  12 A is illustrated in conjunction with the knob or spinner  14 , showing cross-section and the internal slider  200 , not visible in the previous illustrations. The internal, distally facing recess  15  in knob  14  is visible in this view, and is sized to be of sufficient length that it inherently serves as a strain relief to the deflectable stylet  16 , preventing kinking or bending of the stylet at the point it exits the slider  200 . Recess  15  also assists the physician in repositioning his hand when moving between proximal and distal positions relative to the handle, in that the portion of the connector assembly distal to the connector pin is immediately adjacent the distal end of the knob. 
         [0026]    The slider  200  generally takes the form of a rod provided with external threading  202  which engages internal threading  204  within knob  14 . At the proximal end of the slider  200  is a collar  206  that engages corresponding grooves in the molded handle halves, not visible in this drawing, to prevent rotation of the slider  200  relative to the handle. Thus, rotation of the knob  14  relative to the handle causes longitudinal movement, but not rotational movement of the slider  200 . The outer tube of deflectable stylet  16  is mechanically coupled to the slider  200 , while the tension wire  208  within the stylet  16  is anchored to the handle. Thus, on distal movement of the slider  200  relative to the handle  12 A, the outer tube of the stylet is moved with respect to the tension wire  208 , causing tension wire  208  to apply tension to the tip of the stylet and deflecting it, in the manner described above in the various cited patents pertaining to deflectable stylets. Tension wire  208  is anchored to a threaded rod  210  which is adjusted longitudinally by means of a hex nut  212 , which is fixedly mounted in the handle. 
         [0027]    As illustrated, the knob  14  and the slider  200  may be longitudinally slid as a unit without rotation in a distal direction with respect to the handle. This provides an alternative mechanism for applying tension to tension wire  208  and deflecting stylet  216 . Deflection of the stylet by this mechanism is convenient in the case in which the physician wants to only very briefly and very quickly induce a curve to facilitate entry of the lead into a desired location, for example, into the coronary sinus or for navigating the lead through the vena cava and through the tricuspid valve. Such deflection may be useful for prolapsing the lead in a manner that allows for easy insertion of the lead tip through a valve, for example. 
         [0028]    In the embodiment illustrated, the slider is provided with an internal bore  214  which may receive the connector pin of an implantable lead. In this case, the bore  214  should be of larger diameter than the connector pin, so that the lead may be rotated with respect to the stylet  216 . Alternatively, the bore  214  may be omitted, with the connector pin simply lying adjacent the distal end of the slider  200 . 
         [0029]      FIG. 4  illustrates a cut-away view through the distal portion of a deflectable stylet handle in conjunction with an attachment according to the invention, to which the connector pin of a lead of the type having a fixation helix is attached. As illustrated, the deflectable stylet control handle corresponds generally to that described in the above cited Greene et al patent and as illustrated in  FIGS. 1-3 . Handle  12 A, knob or spinner  14 , deflectable stylet  16  and tension wire  208  correspond to identically numbered components as illustrated in  FIGS. 1-3  and discussed above. Slider  200 A of this embodiment corresponds generally to slider  200 . Operation of the deflectable stylet handle in and of itself is identical to that described above in conjunction with  FIGS. 1-3 . It may be noted that the embodiment of  FIG. 4  shows extending screw threads  202 A being cut away in portions. This allows ethylene oxide gas to more easily penetrate the threads during the sterilization process. 
         [0030]    Also illustrated is an attachment  304  according to the present invention mounted to the stylet handle. Attachment  304  includes a generally cylindrical knob  316  from which a generally tubular member  314  extends proximally. Tubular member  314  is mounted with a slip-fit to tubular pin  300  within the distal facing recess  15  of knob or spinner  14 . The attachment  304  may be slid longitudinally within that recess, and may also be rotated with respect to tubular pin  300 . 
         [0031]    At the distal end of the attachment  304  is a distally facing bore in which the connector pin  310  of a pacing lead  312  is inserted and is retained by screw  308 . Lead  312  may be of the type having a fixation helix, wherein the fixation helix is advanced by rotation of this connector pin  310 . Rotation of the fixation helix is discussed further below. 
         [0032]    Tubular pin  300  is mounted within recess  214 A, in the distal end of slider  200 A, and is retained therein frictionally, by adhesive or otherwise. Plug  306  is mounted to the proximal end of the tubular member  314 . Located within the proximally extending tubular member  314  of attachment  304  is a bushing  302 , which surrounds a tubular pin  300  that is in turn mounted around deflectable stylet  16 . Bushing  302  is adhesively or otherwise bonded to the interior of the tubular member  314 , and is free to rotate with respect to tubular pin  300 . Bushing  302  provides the friction fit between attachment  304  and tubular pin  300  to allow attachment  304  to be slid in a controlled manner along tubular pin  300 . Pin  300  thereby allows for an increase in the range of available controlled longitudinal movement of attachment  304  relative to a deflectable stylet handle. 
         [0033]    The current invention provides an efficient mechanism for adjusting the position of the stylet  16  within the body of lead in a controlled manner using only a single hand. In contrast, the prior art mechanisms discussed above for adjusting lead position with respect to the stylet require the detachment of the lead from the handle before longitudinal movement of the lead body is possible. In most cases, these prior art mechanisms require two hands to operate, and do not allow for controlled movement of the lead body with respect to the handle. 
         [0034]      FIG. 5  is a cut-away view of components that are similar to those illustrated in  FIG. 4 , with all identically numbered components correspond to those in  FIG. 4 . In this view, attachment  304  is shown advanced distally on tubular pin  300  out of the recess in knob or spinner  14 , for a distance “A” which may be, for example, about an inch. Because tubular pin  300  extends distally to the end of knob or spinner  14 , it is possible to move the attachment  304  to a point wherein only the proximal most portion of the attachment is located within the recess within spinner or knob  14 , while retaining the correct alignment of the attachment with respect to the deflectable guidewire and deflectable guidewire handle. 
         [0035]    The current invention may be used to adjust a stylet length to that of a particular lead. The stylet length may be adjusted by a length “A” as shown by extended position  320  of  FIG. 5 . For example, in some instances, lead lengths may vary by several inches. For leads that are longer, the attachment may be positioned in its most retracted position so that the tip of the stylet is positioned at the end of the lead. For leads that are shorter, the attachment  304  may be positioned at a more extended location within the recess of spinner or knob  14 . The attachment therefore allows the flexibility to manufacture longer lead or catheter bodies that may be trimmed and reworked if a defect in the connector is experienced. This reduces overall manufacturing costs, since fewer leads or catheters must be disposed of because of manufacturing defects. 
         [0036]    In addition to providing an efficient mechanism for adjusting stylet length, the current invention further provides a mechanism for rotating a helical electrode. As stated previously, the connector pin  310  of a pacing lead  312  is inserted and retained by screw  308  of attachment  304 . Therefore, rotation of attachment  304  will result in rotation of the connecting pin and any interconnected helical electrode that is positioned at the distal end of the lead. This allows the helical electrode to be attached to, or detached from, adjacent tissue. It may be noted that the current invention is suitable for use with both retractable and fixed-screw helical electrodes, and is particularly useful when retractable helical electrodes are used. 
         [0037]      FIG. 6  is a cut-away view of another embodiment of handle assembly  10  and attachment  304 , as illustrated in the figures discussed above. In this Figure, all components corresponding to those in  FIGS. 4 and 5  are labeled with the same reference numbers as used in the previous  FIGS. 4 and 5  for ease of reference. As in the embodiments discussed above, this embodiment includes a handle fabricated of two molded plastic parts, joined together essentially along a longitudinal line extending the length of the handle. One of the two handle halves shown as  12 A is illustrated in conjunction with the knob or spinner  14 , shown in cross-section, and the internal slider  200 , not visible in the previous illustrations. 
         [0038]    The embodiment of the handle shown in  FIG. 6  is very similar to that shown in previous  FIGS. 4 and 5 , with a few exceptions. For example, tension wire  208  is anchored to wire anchor  330 , and is not longitudinally adjustable as is the tension wire shown in  FIGS. 4 and 5 . Instead, tension wire  208  is adhesively bonded or potted into anchor  330  by epoxy for superior tensile strength. 
         [0039]      FIG. 6  further illustrates another embodiment of the attachment. As in the embodiments discussed above, the attachment of this embodiment is fabricated of two molded plastic parts, joined together essentially along a longitudinal line extending the length of the handle, with the half of the attachment  304   a  being shown in  FIG. 6 . As with the attachment discussed above in reference to  FIG. 5 , this attachment includes a generally cylindrical knob  316  from which a generally tubular member  314  extends proximally. Tubular member  314  is rotatably mounted to tubular pin  300  within the distal facing recess  15  of knob or spinner  14  and is also slidable longitudinally within that recess. In this embodiment, tubular member  314  includes a ball-detent coupling mechanism (not shown in  FIG. 6 ) to be described further below. This coupling mechanism is adapted to be rigidly positioned longitudinally with respect to any of the notches  336  included within pin  334 . Thus, attachment  304   a  may be rigidly re-positioned longitudinally at predetermined intervals along at least a predetermined portion of the length of pin  334  while rotating freely in the notches. 
         [0040]    This embodiment may further include an elastomeric ring-like structure such as O-ring  360  shown positioned in recess  361 . The O-ring allows the attachment to be longitudinally re-positioned at an infinite number of positions using a friction fit with pin  334 . O-ring may be used in addition to, or instead of, the ball-detent coupling mechanism discussed below. 
         [0041]    In the embodiment of  FIG. 6 , attachment  304   a  further includes a lead attachment mechanism that uses a pushbutton clevis to fix the lead pin to attachment  304   a .  FIG. 14  illustrates a cross-section of this pushbutton  340  that resides within a recess  338   a  and couples the connector pin  310  of a pacing lead  312  to the attachment. The pushbutton clevis is discussed further below. This is an alternative coupling mechanism to screw  308  of  FIG. 5 . The embodiment of  FIG. 14  provides the advantage of requiring only a single, one-handed motion to engage and disengage the coupling mechanism as compared to the screw  308  of  FIG. 13 . 
         [0042]      FIG. 7  is a perspective diagram of first and second halves  304   a  and  304   b , respectively, of the attachment of the embodiment of  FIG. 6 , including pushbutton clevis  340 . Pushbutton  340  is adapted to slidably engage within a recess  338   b  of attachment half  304   b , and to further engage in similar recess  338   a  (shown in  FIG. 6 ) of attachment half  304   a  when the attachment halves are coupled together as shown by the dashed lines of  FIG. 7 . The pushbutton is prevented from falling out of recesses  338   b  by a locking travel limit pin  347  shown protruding perpendicularly from a proximal face of the pushbutton. When inserted within the recess, the pushbutton generally resides in either a first loose position, or a second locked position that will be discussed in more detail below. 
         [0043]    Each of the attachment halves further includes a cut-away area  342   a  and  342   b  on the distal face of cylindrical knob  316  of attachment halves  304   a  and  304   b , respectively. This cut-away area accommodates the positioning of a lead connector pin  310  of lead  312 . When the pushbutton is in the loose position, the connector pin  310  of lead  312  may be easily inserted into this cut-away area. Once the lead connector is so positioned, the pushbutton may be snapped into the locked position such that pushbutton  340  traps connector pin  310  within one end of aperture  345 . This fixes the implantable lead  312  in a rigid position with respect to the attachment. Rotation of the cylindrical knob  316  will now rotate the entire lead body, allowing for easy fixation of a helical screw that may be carried at the distal end of the lead body within adjacent tissue. This pushbutton mechanism is further discussed below. 
         [0044]      FIG. 7  further shows the coupling mechanism  348  that is provided to couple to notches  336  included within pin  334 . In one embodiment, this coupling mechanism is a protrusion  348  that may be included on one or both of the attachment halves  304   a  and  304   b . This protrusion may be, for example, one or more stainless steel balls embedded within a respective wall of one or both of attachment halves  304   a  and  304   b . This protrusion is adapted to fit within any of notches  336  to allow the attachment to be selectably positioned at regular intervals along pin  334 . Such a positioning mechanism allows for more controlled positioning of the lead body with respect to the stylet. 
         [0045]    In another embodiment, attachment halves  304   a  and  304   b  do not include a coupling mechanism such as protrusion  348 . Instead, the elastomeric O-ring  360  is positioned in recess  361  between attachment halves  304   a  and  304   b  to fit over tubular pin  334  as shown in  FIG. 6 . The O-ring allows the attachment to be longitudinally re-positioned at an infinite number of positions using a friction fit. Because the O-ring fits loosely within recess  361 , the attachment is able to rotate freely about O-ring  360 , and therefore also rotate freely around pin  334 . In yet another embodiment, both the O-ring  360  and protrusion  348  may be employed in conjunction with tubular pin  334  to provide both longitudinally rigid positioning at discrete intervals, and slipped-fit positioning at locations intermediate the discrete intervals. 
         [0046]      FIG. 8  is a cross-sectional view of the distal end of the attachment with halves  304   a  and  304   b  coupled together, and further illustrating the pushbutton  340  in a loose position. In this position, a connector pin  310  of lead  312  (not shown in this view) may be easily inserted into the aperture formed by cut-away areas  342   a  and  342   b . A connector pin  310  so inserted is not in intimate contact with aperture  345 , and may be easily rotated with respect to the attachment. 
         [0047]      FIG. 9  is a cross-sectional view of the distal end of the attachment halves  304   a  and  304   b  coupled together, and further illustrating the pushbutton  340  in a locked position. A connector pin  310  of lead  312  (not shown in this view) inserted into the recesses  338   a  and  338   b  will be intimate contact with recess  345  so that rotation of the attachment rotates the connector pin  310 . When using a lead having a fixed-screw helical electrode, this rotation will rotate the lead body and the helical electrode. When using a lead employing a retractable helical electrode, this rotation will extend or retract the electrode so the helix may be attached to, or detached from, respectively, adjacent tissue. 
         [0048]    The attachment of the current invention provides a mechanism for easily manipulating a lead assembly with a single hand. Only a single hand is needed to grasp handle assembly  10 , to further rotate or slide knob  14  to deflect a distal tip of a guidewire inserted within a lead, and to rotate attachment  304  to facilitate rotation of the entire lead. Furthermore, using the embodiment of  FIG. 7 , affixing the lead to attachment  304  may be accomplished with a quick snap of pushbutton  340  that may also be performed with the same hand. This easy, one-handed control system of the current invention thus frees up one hand of the physician for other tasks. 
         [0049]    Modifications to the embodiments discussed above are permissible within the scope of the invention, and the possibility of such modification should be understood in conjunction with the claims that follow. For example, in some embodiments, pin  300  might be eliminated, however, in such embodiments, the available range of longitudinal movement of the attachment  304  relative to the deflectable stylet handle would be reduced somewhat. Similarly, in some alternative embodiments, the recess within the knob or spinner  14  might be reduced or eliminated entirely, with the attachment retained in alignment with and mounted to the deflectable stylet handle only by means of tubular pin  300 . Similarly, as noted above, other mechanisms for inducing curvature of the deflectable stylet might be substituted for that employed in the handle as illustrated. For example, a knob or handle might be attached directly to the slider  200 A, and employed to directly move the slider longitudinally, eliminating the necessity for a rotatable knob. As such, the embodiment illustrated above should be considered as exemplary, rather than limiting, when interpreted in conjunction with the claims which follow.