Abstract:
A device and method for removing a guide catheter from about a cardiac lead is disclosed. The device includes a blade for slitting the catheter so that the catheter may be removed from the lead. The blade includes upper and lower angled cutting surfaces which define a notch. The device includes a portion for receiving the lead and guiding the catheter to the blade.

Description:
TECHNICAL FIELD 
     The present invention relates generally to devices for removing guide catheters from leads. More specifically, the present invention relates to notched cutters for slicing and removing guide catheters from implanted leads. 
     BACKGROUND OF THE INVENTION 
     Implanted medical devices, such as pacemakers or other cardiac rhythm management devices, often require that a lead be implanted within the body of a patient to connect the device with a specific portion of the patient&#39;s body, such as the heart. Minimally invasive techniques have been developed to permit these such leads to be implanted within the patient&#39;s body. One example of such a minimally invasive technique is to utilize a guide catheter, requiring only a relatively small incision at the insertion site. 
     Once the implanted lead has been positioned with the patient&#39;s body, the guide catheter needs to be removed from the lead. Often, the guide catheters include an outer sheath made of a reinforced material, such as a polymeric substrate with a steel mesh or reinforcing structure supporting the substrate. Such reinforced materials may be difficult to cut and may cause the cutter to bind, preventing the smooth removal of the catheter from about the lead and the withdrawal of the catheter from the patient&#39;s body. 
     Improvements to the tools and techniques used to remove a guide catheter from about a lead and from the patient&#39;s body are desirable. 
     SUMMARY  
     The present invention relates to a device for removing a guide catheter from about a linear object positioned within a lumen of the guide catheter. The device includes a body with a front edge, a rear edge, an upper edge and a lower edge. A web extends between the lower edge and a distal segment defining a central opening adapted to engage the linear object. The distal segment generally extends from the front edge toward the rear edge and includes an outer surface. The guide catheter extends about the outer surface as the linear object extends through the central opening of the distal segment. A blade is mounted between the lower edge and the outer surface of the distal segment and is supported by the web. The blade including a first cutting portion and a second cutting portion. The first cutting portion extends from the lower edge and is angled from the front edge toward the rear edge as the first cutting portion extends toward the distal segment. The second cutting portion extends from the distal segment toward the lower edge and is angled from the front edge toward the rear edge as the second cutting portion extends toward the lower edge. The first and second cutting portions of the blade form a notch between the lower edge and the distal segment. The blade is positioned to engage the guide catheter as the guide catheter passes about the outer surface of the distal segment. 
     The invention further relates to an assembly for removing a guide catheter from about a cardiac pacemaker lead. The assembly includes a guide catheter with a lumen within which the pacemaker lead is positioned. The pacemaker lead includes a distal end and terminal end, with a lead body extending between. The assembly also includes a cutter for removing the guide catheter from about the lead. The cutter includes a body with a front edge and a lower edge, and a lead management segment including a side opening arcuate member defining a central opening for receiving the lead positioned adjacent the lower edge. The lead management segment is connected to the body by a web. The lead management segment is adapted so that the guide catheter body passes over an outer surface when the lead is within the central opening. The cutter also includes a blade extending between the body and the lead management segment supported by the web. The blade includes a first portion extending from the body toward the lead management segment angling rearward with respect to the front edge, and a second portion extending from the lead management segment toward the body angling rearward with respect to the front edge. The first and second portions of the blade form a notch. The cutter is positioned about the lead adjacent the terminal end with the blade positioned to engage the guide catheter. 
     The present invention further relates to a method of removing a guide catheter from about an implantable cardiac lead. The implantable lead includes a terminal end and a distal end, and a lead body extending between. The guide catheter includes a lumen extending through a linear body with a distal end and a proximal end and a fitting mounted to the proximal end. The lead is positioned within the lumen of the guide catheter with the terminal end extending from the fitting of the guide catheter. Also provided is a cutter including a body with a front edge, a rear edge and a lower edge, a web extending from the lower edge and including a blade arranged toward the front edge. The web includes a lead management segment opposite the lower edge. The lead management segment includes an arcuate side-opening member defining a central opening for receiving the lead body. The blade includes a lower cutting edge adjacent the lead management segment extending rearwardly toward the lower edge and an upper cutting surface adjacent the lower edge extending rearwardly toward the lead management segment. The upper and lower cutting edges define a notch in the blade. The cutter is positioned about the lead body with the lead body positioned within the opening of the lead management segment and the front edge of the cutter toward the fitting of the guide catheter. The blade engages the fitting of the guide catheter. While holding the lead in position relative to the cutter, the guide catheter is drawn rearward along the lead so that the blade engages and slits the guide catheter. The slit guide catheter is removed from about the lead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the invention and together with the detailed description, serve to explain the principles of the invention. A brief description of the drawings is as follows: 
         FIG. 1  is a perspective view of a guide catheter cutter according to the present invention mounted about an implantable cardiac lead in position to remove a guide catheter from about the lead, with a luer hub at the proximal end of the lead partially cut by the cutter. 
         FIG. 2  is a perspective view of the cutter of  FIG. 1 , removed from the cardiac lead. 
         FIG. 3  is a first side view of the cutter of  FIG. 2 , with a blade for cutting the guide catheter within the cutter shown by dashed lines. 
         FIG. 4  is a second opposite side view of the cutter of  FIG. 2 . 
         FIG. 5  is a first enlarged view of the cutter of  FIG. 2 , showing the cutting edge of the blade and a forward lead engaging structure. 
         FIG. 6  is a front end view of the cutter of  FIG. 2 . 
         FIG. 7  is an enlarged front end view showing the cutting edge of the blade and the forward lead engaging structure. 
         FIG. 8  is a first cross-sectional view of the cutter of  FIG. 2 , taken along line  8 - 8 . 
         FIG. 9  is an enlarged view of the cross-sectional view of  FIG. 9 . 
         FIG. 10  is a second cross-sectional view of the cutter of  FIG. 2 , taken along line  10 - 10 . 
         FIG. 11  is an enlarged view of the blade of the cutter of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary aspects of the present invention which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     When cardiac pacemakers or other implanted electro-stimulus devices are implanted in a patient&#39;s body, a lead may be used to connect the device to an area of the patient&#39;s body where the stimulus is desired. While such implantation procedures are necessarily invasive, techniques and devices have been developed to reduce the size and extent of invasion required. When implanting leads within or adjacent to a patient&#39;s heart for connection to a pacemaker, it is known to use a guide catheter to position the distal end of the lead in the desired location. Guide catheters may include a central axial lumen within which the lead is placed. The distal end of the guide catheter is then maneuvered so that the lead is properly placed within or adjacent the patient&#39;s heart. Such a guide catheter permits precise location of the distal end while requiring only a fairly small incision. Such catheter devices and techniques are well known. 
     Once the pacemaker lead has been positioned, the guide catheter must be removed from about the lead. Often these guide catheters include a luer hub or other similar fitting at a proximal end and a linear body extending from the fitting to the distal end of the catheter. A proximal end  11  of such a guide catheter  10  with a proximal fitting  12  (shown as a luer hub) is shown in  FIG. 1 . A cardiac lead  14  includes a linear lead body  16  inserted within a central axial lumen of a linear body  22  of catheter  10  and a terminal end  18  which is configured to be connected with a pacemaker (not shown) and extends from proximal end  11  of catheter  10 . Lead body  16  defines a smaller diameter than terminal end  18 . Lead body  16  includes a distal end  20  which is positioned adjacent distal end  13  of catheter  10 . 
     Removal of catheter  10  from about lead  14  should be preferably accomplished without disturbing or displacing distal end  20  of lead  14 . However, to keep catheter  10  to the smallest possible diameter to minimize the invasiveness of the placement procedure, and to reduce bleed back pressure during placement, the central axial lumen of linear body  22  of catheter  10  is sized to closely fit about lead body  16 . Linear body  22  is not sized to be removed across terminal end  18 . Thus it is advantageous to have a guide catheter cutter  24  to slit catheter  10  lengthwise and permit removal of guide catheter  10  from about lead  14 . 
     Referring now to  FIGS. 2 to 4 , cutter  24  includes a handle  26  with an upper edge  28 , a lower edge  30 , a front edge  32  and a rear edge  34 . In either side of handle  26  are a pair of gripping recesses  36  and  38 . Extending from lower edge  30  adjacent front edge  32  is a web  40  which in conjunction with handle  26  supports a blade  52 . Blade  52  is positioned within handle  26  and web  40  is a position as shown by the hidden lines in  FIG. 3 . Opposite handle  26  on web  40  is a distal lead management segment  44  with a forward portion  46  defining a smaller diameter and a rear portion  48  defining a larger diameter. Distal lead management segment  44  defines a central opening  58  (shown in  FIGS. 5 ,  6  and  7 ) within a side opening  47  in forward portion  46  and a side opening  49  in rear portion  48 . The side openings  47 ,  49  are configured to deform away from the lower edge of the lead body so as to enlarge the side opening allowing lead  14  to be snapped into central opening  58  from the side. 
     Extending from lower edge  30  adjacent rear edge  34  is a proximal lead management segment  42 . As shown, proximal lead management segment  42  is connected to lower edge  30  by a web  56 . Alternatively, proximal lead management segment  42  may be directly mounted to lower edge  30 . Proximal lead management segment  42  defines a central opening  60  (shown in  FIGS. 6 ,  7 , and  10 , below), axially arranged with central opening  58 . A side opening  43  allows lead  14  to be snapped into opening  60  from the side. 
     A forward extension or nose  50  extends from the front of web  40  forward of blade  52 . As shown in  FIG. 1 , luer hub  12  includes a proximal end  51 , opposite proximal end  11  of catheter body  22 , which is flared or larger in diameter than lead body  16 . This flared end  51  permits a device such as a blood back flow valve or hemostasis valve to be removably fitted to luer hub  12 . Flared end  51  also permit nose  50  to be inserted within luer hub  12  along lead body  16  so that blade  52  can engage and cut luer hub  12  and catheter body  22  from about lead  14 . Web  40  also includes a pair of wings  54  on either side of web  40  proximate the transition from first portion  46  and second portion  48 . These wings serve to force catheter  10  from about lead  14  once blade  50  has slit catheter  10  and catheter  10  has been moved proximally along lead  14 . Catheter  10  is positioned about forward portion  46  until wings  54  urge catheter  10  from about lead  14  and distal lead management segment  44 . As shown in  FIG. 1 , nose  50  is within the lumen of catheter  10  and blade  52  how just begun to slit luer hub  12 . Flared end  51  of luer hub  12  has not yet reached wings  54 . 
     Referring now also to  FIG. 5 , blade  52  includes an upper cutting edge  64  and a lower cutting  66 , defining a notch  62  therebetween. Upper cutting edge  64  extends forwardly from notch  62  into lower edge  30  of handle  26 . Lower cutting edge  66  extends forwardly from notch  62  into nose  50 . Notch  62  thus defines the rearmost cutting portion of blade  52  and is positioned between nose  50  and lower edge  30  of handle  26 . Notch  62  is preferably positioned adjacent nose  50 . The positioning of notch  62  as the rearmost cutting portion of blade  52  provides improved resistance to binding of blade  52  during cutting or slitting of catheter  10  from about lead  14 . 
     Guide catheters such as catheter  10 , while flexible to aid insertion and placement of lead  14 , may include a reinforcing material within linear body  22 . This reinforcing material may be a steel or aramid mesh or braid embedded within body  22 . This mesh, as well as the substrate material of linear body  22  must be cut by blade  52  to remove catheter  10  from lead  14 . Cutters have rearwardly extending blades are known, and these blades may include forward edges to be inserted within the central lumen of catheter  10  to begin slitting catheter  10 . However, catheter  10  and the reinforcing material within linear body  22  may resist slitting by the blade and may “climb” the rearwardly angled cutting edge, causing the blade to bind instead of smoothly and cleanly cutting linear body  22 . Known cutter designs also may bind if the cutting of linear body  22  is stopped and started at an intermediate point between the distal and proximal ends. 
     Lower cutting edge  66  of blade  52  adjacent nose  50  is angled forward from notch  62  to aid in insertion of blade  52  within the lumen of catheter  10 . Above notch  62 , upper cutting edge  64  is angled to prevent catheter  10  from climbing blade  52  away from nose  50  and causing cutter  24  to bind. An enlarged view of blade  52  is shown in  FIG. 11 . Blade  52  includes a body  68  which is enclosed within body  26  and web  40  of cutter  24 . Lower cutting edge  66  includes a forward point  70  which is encased within nose  50 . Upper cutting edge  64  includes a forward point  72  which is encased within body  26  adjacent lower edge  30  and front edge  32 . Blade  52  may be preferably positioned within cutter  24  by having body  26 , web nose  40  and nose  50  molded about blade  52 , if cutter  24  is made of a moldable material. Other methods of construction and assembly may also be used for cutter  24 . The configuration of notch  62  also improves the ability of cutter  24  to restart cutting of linear body  22  after stopping at an intermediate point between proximal end  11  and distal end  13 . 
     Referring now to  FIGS. 6 to 9 , central opening  58  of distal lead management segment  44  is shown in greater detail. Side openings  47  and  49  permit lead body  16  to be snapped within central opening  58 . Side openings  47  and  49  are slightly smaller in diameter than lead body  16 . Distal lead management segment  44  is made of a resilient deformable material which permits entry of lead body  16  through openings  47  and  49  and then slidably and releasably holds lead body  16  within central opening  58 . Forward portion  46  defines a smaller diameter than rear portion  48 , and the diameter of forward portion  46  closely matches the diameter of lead  16 . This permits lead body  16  to slide through forward portion  46  without excessive sideways movement. Nose  50  can then ride along lead body  16  to guide lower cutting edge  66  of blade  52  into the lumen of catheter  10  to slit catheter  10 . 
     Beyond wings  54 , distal lead management segment  44  defines a slightly larger diameter within rear portion  48 . As cutter  24  is moved along lead body  16 , catheter  10  is slit by blade  52  and urged from about lead  14  by wings  54 . Rear portion  48  maintains control over the movement of lead  14  so that lead  14  can be separated from catheter  10 . It is not necessary for rear portion to be as closely matched in size to lead body  16  and the enlarged diameter of rear portion  48  may reduce friction or other resistance to movement of cutter  24  along lead  14 . 
     Referring now to  FIGS. 6 ,  7  and  10 , second arcuate lead engaging portion  42  is shown. Central opening  60  of proximal lead management segment  42  is axially aligned with central opening  58  of distal lead management segment  44 . Central opening  60  is larger in diameter than either front portion  46  or rear portion  48  of distal lead management segment  44 . Side opening  43  permits lead  14  to be snapped into opening  60 , as proximal lead management segment  42  is constructed of a resilient deformable material, similar to distal lead management segment  44 . Central opening  60  and side opening  43  may be made large enough to accommodate terminal end  18  of lead  14 . Alternatively, central openings  58  and  60  and side openings  43  and  47  may be made the same size if accommodation of terminal end  18  is not required, or if a new terminal end is developed which is similar in diameter to the linear body  22 . 
     In some implantation procedures, terminal end  18  of lead  14  may be positioned too close to luer hub  12  to permit lead body  16  to be snapped into both central opening  58  and central opening  60 . For such situations, side opening  43  and central opening  60  may accommodate the larger diameter of terminal end  18 . Cutter  24  can then be advanced along lead  14 , slitting hub  12  and linear body  22  until lead body  16  is within opening  60 , as shown in  FIG. 1 . At this position, cutter  24  can be held in position relative to lead  14  and catheter  10  moved rearward to completing the slitting and removal of catheter  10  from about lead  14 . Alternatively, terminal end  18  can remain within central opening  60  as catheter  10  is pulled rearward to be slit and removed from about lead  14 . 
     Once catheter  10  has been removed from about lead  14 , lead  14  may be removed from central openings  58  and  60  of cutter  24  through side openings  43 ,  47 , and  49 . 
     The embodiments of the inventions disclosed herein have been discussed for the purpose of familiarizing the reader with novel aspects of the present invention. Although preferred embodiments have been shown and described, many changes, modifications, and substitutions may be made by one having skill in the art without unnecessarily departing from the spirit and scope of the present invention. Having described preferred aspects and embodiments of the present invention, modifications and equivalents of the disclosed concepts may readily occur to one skilled in the art. However, it is intended that such modifications and equivalents be included within the scope of the claims which are appended hereto.