Abstract:
This disclosure describes various examples of multi-purpose tools and associated methods for safely gaining access to extravascular spaces. The multi-purpose tools described herein are particularly suited for safely gaining access to the sub-sternal space underneath the sternum/ribcage as well as tunneling subcutaneously above the ribcage for the purpose of positioning of a medical electrical lead. This eliminates the need for separate tools for tunneling in different extravascular spaces by providing a single tool capable of the multiple uses.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure pertains to multi-purpose tools and associated methods for safely gaining access to extravascular spaces, and more particularly to those suited to safely gain access to at least two such spaces in a patient for the purpose of positioning of a medical electrical lead therein. 
       BACKGROUND 
       [0002]    Implantable medical electrical leads, included in systems that are known in the art for delivering cardiac therapy and/or for providing cardiac monitoring, are often implanted transvenously within a heart of a patient. But extravascular implant sites may be preferred, for example, in those patients where vascular access is difficult, or because transvenous leads can become fibrosed in the heart over time, which makes lead revision and extraction procedures challenging. 
       SUMMARY 
       [0003]    This disclosure describes various examples of multi-purpose tools and associated methods for safely gaining access to extravascular spaces. The multi-purpose tools described herein are particularly suited for safely gaining access to the sub-sternal space underneath the sternum/ribcage as well as tunneling subcutaneously above the ribcage for the purpose of positioning of a medical electrical lead. 
         [0004]    In one example, this disclosure is directed to a multi-purpose tunneling tool comprising an elongate tunneling member, a handle, and an alignment horn. The elongate tunneling member includes a relatively straight proximal segment, a distal segment, and a blunt tip. The proximal segment of the elongate tunneling member defines a longitudinal axis of the tunneling member. The distal segment of the elongate tunneling member extends along a single pre-formed bend from the proximal segment to the blunt tip. The distal segment elongate tunneling member is co-planar with the proximal segment and the segments enclose an angle of between approximately 150 degrees and approximately 170 degrees. The handle includes a lock-and-release mechanism that forms a junction between the handle and the proximal segment of the tunneling member. The alignment horn extends from a first end thereof to a second end thereof, alongside and coplanar with the tunneling member. The alignment horn is relatively straight between the first and second ends thereof and substantially parallel to the tunneling member proximal segment. The first end of the alignment horn is coupled to the handle. The lock-and-release mechanism of the handle is configured to allow detachment of the handle from the tunneling member, and to allow rotation of the tunneling member 180 degrees about the longitudinal axis thereof, relative to the handle, from a first position to a second position, the tunneling member distal segment extending directly toward the alignment horn in the first position, and the tunneling member distal segment extending directly away from the alignment horn in the second position. 
         [0005]    In another example, this disclosure provides a multi-purpose tunneling tool comprising an elongate tunneling member, a handle, and an alignment horn. The elongate tunneling member includes a relatively straight proximal segment, a distal segment, and a blunt tip, the proximal segment defining a longitudinal axis of the tunneling member, the distal segment extending along a single pre-formed bend from the proximal segment to the blunt tip, the distal segment being co-planar with the proximal segment, and the segments enclosing an angle of between approximately 150 degrees and approximately 170 degrees. The hannde is joined to the proximal segment of the tunneling member. The alignment horn includes a first end, a second end, and a blunt tip terminating the second end, the horn extending from the first end to the second end alongside and coplanar with the tunneling member, and the horn being relatively straight between the first and second ends thereof and parallel to the proximal segment of the tunneling member, the first end of the alignment horn being coupled to the handle, the second end of the alignment horn extending along a single pre-formed bend, such that the blunt tip of the horn is directed away from the tunneling member, the second end being co-planar with a relatively straight remainder of the horn, and the second end and remainder enclosing an angle of between 150 degrees and 170 degrees. 
         [0006]    In a further example, this disclosure provides a method for employing a tunneling tool. The method includes creating a sub-sternal tunnel in a patient by advancing an elongate tunneling member of the tool beneath a sternum of the patient, after having inserted a blunt tip of the tunneling member through an incision site of the patient, the advancing being guided by an alignment horn of the tool, the tunneling member further including a relatively straight proximal segment, and a distal segment extending along a single pre-formed bend from the proximal segment to the blunt tip, the distal segment being co-planar with the proximal segment, and the alignment horn extending from a first end thereof to a second end thereof, alongside and coplanar with the tunneling member, the horn being relatively straight between the first and second ends thereof and parallel to the proximal segment of the tunneling member. The method also includes removing the tunneling member of the tool from the sub-sternal tunnel and positioning a distal portion of a medical electrical lead within the sub-sternal tunnel, after removing the tunneling member. The method further includes creating a subcutaneous tunnel superficial to a rib cage of the patient, after creating the sub-sternal tunnel and removing the tunneling member of the tool therefrom, by inserting a blunt tip of the alignment horn of the tool through the incision site and then advancing the alignment horn subcutaneously around the rib cage to a subcutaneous pocket of the patient, the blunt tip of the alignment horn terminating the second end of the horn, and the second end of the horn extending along a single pre-formed bend, such that the blunt tip of the horn is directed away from the tunneling member, the second end being co-planar with a relatively straight remainder of the horn and positioning a proximal portion of the medical electrical lead within the subcutaneous tunnel, so that a connector terminal of the lead extends into the subcutaneous pocket. 
         [0007]    In another example, the disclosure provides a method for employing a tunneling tool to create a subcutaneous tunnel within a patient, and to position a proximal portion of a medical electrical lead within the subcutaneous tunnel, after creating a sub-sternal tunnel in the patient with the tunneling tool. The method comprises rotating an elongate tunneling member of the tool 180 degrees relative to a handle of the tool so that a blunt tip of the tunneling member is directed away from an alignment horn of the tool, the tunneling member further including a relatively straight proximal segment joined to the handle and a distal segment extending along a pre-formed bend from the proximal segment to the blunt tip, the distal segment being coplanar with the with the proximal segment, and the alignment horn extending from a first end thereof to a second end thereof, alongside and coplanar with the proximal segment of the tunneling member, the horn being relatively straight between the first and second ends thereof and parallel to the proximal segment of the tunneling member; advancing the rotated tunneling member subcutaneously around a rib cage of the patient until the blunt tip reaches a subcutaneous pocket of the patient; detaching the handle from the proximal segment of the advanced tunneling member, the handle including a lock-and-release mechanism joining the proximal segment of the tunneling member thereto; attaching a connector terminal of the proximal portion of the medical electrical lead to the proximal segment of the advanced tunneling member, after detaching the handle; and applying a pull force to the distal segment of the advanced tunneling member, after attaching the connector terminal of the lead proximal portion to the proximal segment thereof, to bring the connector terminal through the subcutaneous tunnel and into the subcutaneous pocket. 
         [0008]    This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the apparatus and methods described in detail within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and the description below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1A-B  are schematics showing an exemplary extravascular implant of an exemplary extravascular medical system that includes an implantable pulse generator and an implantable medical electrical lead coupled thereto. 
           [0010]      FIG. 2  is a schematic showing an access site for making a passageway between a patient&#39;s diaphragm and xiphoid process of sternum to create a sub-sternal tunnel in which to position the distal portion of a medical electrical lead. 
           [0011]      FIGS. 3A-3C  are schematics illustrating various views of an example multi-purpose tool for creating both a sub-sternal tunnel and a subcutaneous tunnel in a patient. 
           [0012]      FIG. 4A-C  are schematics outlining methods for using an example multi-purpose tool to implant a medical electrical lead in a patient. 
           [0013]      FIG. 5A-B  are schematics of various plan views of another example multi-purpose tool for creating both a sub-sternal tunnel and a subcutaneous tunnel in a patient. 
           [0014]      FIGS. 6A-B  are schematics of various plan views of another example multi-purpose tool. 
           [0015]      FIG. 7A-D  are schematics outlining another example method for using an example multi-purpose tool to implant a medical electrical lead. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The following detailed description is exemplary in nature and is not intended to limit, in any way, the scope, applicability, or configuration of the tools and techniques described in this disclosure. Rather, the following description provides practical examples, and those skilled in the art will recognize that some of the examples may have suitable alternatives. 
         [0017]      FIGS. 1A-B  are schematics showing an exemplary extravascular implant of an exemplary extravascular medical system  10  that includes an implantable pulse generator  14  and an implantable medical electrical lead  16  coupled thereto. Pulse generator  14  is shown implanted in a subcutaneous space, or pocket formed on the left mid-axillary line of a patient  12 , superficial to the patient&#39;s ribcage. Pulse generator  14 , which may be configured to provide cardiac pacing and/or defibrillation therapy, includes a hermetically sealed housing in which the appropriate electronics and a power supply are contained, and which is formed from a conductive material, such as titanium, or from a combination of conductive and non-conductive materials. Pulse generator  14  further includes a connector module  145  by which lead  16  is electrically coupled to the electronics contained therein, for example, by electrical contacts contained within connector module  145  and a corresponding hermetically sealed feedthrough assembly, such as is known in the art. The conductive material of the pulse generator housing may be employed as an electrode, for example, to provide the aforementioned therapy in conjunction with one or more pace/sense electrodes  22 ,  26  and/or a defibrillation electrode  24  of lead  16 . A proximal portion  16 - p  of lead  16  is shown extending medially from pulse generator  14  toward a sternum  13  of the patient, for example, within a subcutaneous or submuscular tunnel above the ribcage, and a distal portion of lead  16  is shown extending in a superior direction adjacent to the sternum  13 , for example within a tunnel formed in a sub-sternal space  3  (e.g., the loose connective tissue and/or sub-sternal musculature of the anterior mediastinum), wherein lead  16  bends in proximity to a xiphoid process  20  of sternum  13 , to extend from the subcutaneous tunnel to the sub-sternal tunnel. With reference to  FIG. 1B , sub-sternal space  3  may be generally viewed as being bounded laterally by pleurae  39  that enclose the patient&#39;s lungs, posteriorly by the pericardial sac  15  that encloses the patient&#39;s heart  6 , and anteriorly by the sternum  13 . In some instances, the anterior wall of the anterior mediastinum may also be formed by the transversus thoracis muscles and one or more costal cartilages. 
         [0018]      FIG. 2  is a schematic showing an access site A for making a passageway between a patient&#39;s diaphragm  19  and xiphoid process  20  of sternum  13 , for example, to create the aforementioned sub-sternal tunnel in which to position the distal portion of medical electrical lead  16 . After making a superficial incision, an operator, using tools and techniques known to those skilled in the art, may open a passageway between diaphragmatic attachments  18  and diaphragm  19 , for example, by blunt dissection, in which the operator may employ a tunneling tool, for example, the Medtronic® Model 6996T, to both create the passageway and then form a sub-sternal tunnel (e.g. along the dotted line of  FIG. 2 ). However, because the boney structure of the sternum inhibits external palpation, the operator must take extra care, during the blunt dissection and/or tunneling, not to injure sub-sternal structures or the chest cavity, which could compromise the pleura  39  of the lungs or the heart  6 . Thus, tools disclosed herein, for the purpose of passing a medical electrical lead into sub-sternal and subcutaneous regions (e.g., as shown in  FIG. 1 ), help an operator to gaining access and/or form both a sub-sternal tunnel, for example, in a more controlled fashion that mitigates the risk of injuring bodily organs, and a subcutaneous tunnel. 
         [0019]      FIG. 3A  is a plan view of a multi-purpose tool  900  for creating both a sub-sternal tunnel and a subcutaneous tunnel in a patient, according to some embodiments.  FIG. 3A  illustrates tool  900  including a handle  950 , an elongate tunneling member  920 , which has a proximal segment  921  joined to handle  950 , and an alignment horn  910 , which has a first end  911  coupled to handle  950 , and which extends, alongside and coplanar with tunneling member  920 , from first end  911  to a second end  912  of horn  910 , being relatively straight therebetween, and parallel to tunneling member proximal segment  921 .  FIG. 3A  further illustrates each of tunneling member  920  and alignment horn  910  including a blunt tip  902 ,  901 , wherein a distal segment  922  of tunneling member  920  extends along a single pre-formed bend from proximal segment  921  to blunt tip  902 , such that blunt tip  902  is directed toward alignment horn  910 , and such that tunneling member proximal segment  921  and distal segment  922  are coplanar and enclose an angle β. In one example, that angle β may be between approximately 150 degrees and approximately 170 degrees. However, the angle β may, in other examples, be greater than 170 degrees (but less than 180 degrees) and less than 150 degrees (but greater than 90 degrees). Similarly, second end  912  of alignment horn  910  is shown extending along a single pre-formed bend and being terminated by blunt tip  901 ; second end  912  of alignment horn  910  is coplanar with the relatively straight remainder of horn  910 . Thus, alignment horn  910  may, similar to tunneling member  920 , include a relatively straight first (or proximal) segment and a curved second (or distal) segment that extends along a single pre-formed bend from the straight first segment to blunt tip  901 , such that blunt tip  901  is directed away from tunneling member  920 . An angle enclosed by second end  912  and the straight remainder of alignment horn  910  may be similar to angle β of tunneling member  920 . In other instances, the angle β of alignment horn  910  may be greater than or less than the angle β of tunneling member  920 . 
         [0020]    According to an exemplary embodiment, tunneling member  920  is formed from a medical grade metal rod, such as a series  300  stainless steel rod having a diameter in a range from approximately 0.1 inch (2.5 mm) to approximately 0.14 inch (3.5 mm), for example, approximately 0.122 inch (3 mm), and a length in a range from five inches (12.7 cm) to approximately eleven inches (28 cm), for example, approximately eight inches (20 cm); and handle  950  and alignment horn  910  are each formed from a relatively hard medical grade polymer, or a combination of medical grade metal and polymer, wherein horn  910  may extend over a length in a range from approximately five inches (12.7 cm) to approximately eleven inches (28 cm). In some alternate embodiments, tunneling member  920  may also be formed from a relatively hard medical grade polymer. Alignment horn  910 , having the relatively straight extent (first end  911  or proximal/first segment) coplanar with, and parallel to the relatively straight extent of proximal segment  921  of tunneling member  920 , provides an external reference for an operator who advances blunt tip  902  of tunneling member  920  within a body of a patient to form a sub-sternal tunnel with tool  900 , as is described below in conjunction with  FIG. 4A . The pre-formed bend of the distal segment  922  of tunneling member  920 , which biases blunt tip  902  toward alignment horn  910 , can cause tip  902  to ‘ride’ adjacent an underside of sternum  13  during sub-sternal tunneling; whereas, the pre-formed bend of alignment horn second end  912 , in conjunction with blunt tip  901 , make tool  900  suitable for forming, with alignment horn  910 , a subcutaneous tunnel that curves around the patient&#39;s ribcage, as described below in conjunction with  FIG. 4B . In other embodiments, alignment horn  910  may be relatively straight for the entire length form handle  950  to blunt tip  901 . 
         [0021]    With further reference to  FIG. 3A  in conjunction with  FIG. 3B , which is a cross-section view through section line B-B of  FIG. 3A , according to some embodiments, alignment horn  910  may include an open channel  917  that extends from first end  911  to blunt tip  901  (represented by a dashed line in  FIG. 3A ), an entirety of which is directed away from tunneling member  920 . Channel  917  may further extend into handle  950 , as indicated by the dashed lines in  FIG. 3A , and as designated with reference numeral  957  in  FIG. 3C .  FIG. 3B  illustrates channel  917  having a width W and a depth D, for example, each being approximately the same or slightly larger than an outer diameter of a body of lead  16 , to accommodate lead  16  being inserted therein. Alternate configurations of open channel  917  are not outside the scope of the instant application, for example, like those described for an open channel  36  of a shaft  34  used for tunneling in a co-pending and commonly assigned United States Patent Application having the pre-grant publication number 2015/0133952, the description of which are hereby incorporated by reference in its entirety. According to the illustrated embodiment, after employing horn  910  to form the aforementioned subcutaneous tunnel, the operator may advance a proximal portion of a medical electrical lead along open channel  917 , for example, proximal portion  16 - p  of lead  16 , to position the proximal portion within the subcutaneous tunnel, as described in greater detail below. 
         [0022]      FIG. 3A  further illustrates handle  950  of multi-purpose tool  900  including an optional lever  952 , which is part of an optional lock-and-release mechanism that may form a junction between handle  950  and proximal segment  921  of tunneling member  920 . According to embodiments that include the mechanism, lever  952 , when lifted, or rotated, per arrow R, allows an operator to detach handle  950  from tunneling member  920 , for example, prior to using alignment horn  910  to create the aforementioned subcutaneous tunnel. An enlarged detail view of the optional mechanism, which is enclosed within a shell of handle  950 , is shown in  FIG. 3A , wherein a block  955  is coupled to lever  952  via a dowel  956 , and defines a portion  905  of a channel that extends within handle  950 , and through which tunneling member proximal segment  921  extends. Channel portion  905 , when offset from, or misaligned with, a remainder of the channel, locks tunneling member  920  with respect to handle  950 , but, when lever  952  is rotated per arrow R, block  955  is moved to align channel portion  905  and thereby release tunneling member  920 . Lever  952  may be formed from polycarbonate, and block  955  from stainless steel, PEI Ultem™ or PEEK. Although a specific lock and release mechanism is illustrated in  FIG. 3A  for exemplary purposes, other lock and release mechanisms may be used in handle  950 , including some of those described elsewhere herein. 
         [0023]      FIG. 3C  is an enlarged detail view inside a yoke of handle  950  that illustrates another optional mechanism of multi-purpose tool  900 , wherein the mechanism is an adjustment mechanism that allows an operator to move alignment horn  910  into a plurality of positions relative to tunneling member  920 , while maintaining the parallel orientation therebetween. For example, the operator may move horn  910  from the position shown in  FIG. 3A  to others, per arrow A of  FIG. 3A , which are closer to tunneling member  920 , so that tool  900  can accommodate various sizes of patients, as described in greater detail below.  FIG. 3C  illustrates the adjustment mechanism being formed by a shank S 9  of alignment horn  910  that is mounted in sliding engagement within a slot  951  of the handle yoke. In some embodiments, a flat, or leaf spring member (shown with dashed lines) may be mounted to a face of shank S 9 , and interface with a confronting face of slot  951  to hold alignment horn  910  in place by preventing horn  910  from freely sliding within slot  971 , while allowing the operator to forcibly slide horn  910  to various positions. Although an example adjustment mechanism is illustrated in  FIG. 3C  for exemplary purposes, other adjustment mechanisms may be used in handle  950 , including some of those described elsewhere herein. 
         [0024]      FIG. 4A-C  are schematics outlining methods for using multi-purpose tool  900  or other similar multi-purpose tool.  FIG. 4A  illustrates tunneling member  920  of tool  900  having been inserted through an incision site IS of a patient and then advanced in a superior direction, per arrow SUP, beneath the patient&#39;s sternum  13 , wherein alignment horn  910  of tool  900 , as an external reference, guides the superior and sub-sternal advancement of tunneling member blunt tip  902 . As was mentioned above, the pre-formed bend of tunneling member  920  biases blunt tip  902  toward horn  910  so that tip  902  rides adjacent to the underside of sternum  13  during the sub-sternal tunneling. Once the operator advances blunt tip  902  enough to create a sub-sternal tunnel of sufficient length, for example, being limited by the aforementioned length of tunneling member  920 , and/or being stopped by a leading edge of handle  950 , from which tunneling member  920  and horn  910  extend, an introducer sheath (not shown) may be advanced over tunneling member  920 , for example, after detaching handle  950  therefrom. (Alternately, the introducer sheath may be positioned around tunneling member  920  prior to forming the sub-sternal tunnel therewith.) Then, the operator may remove tunneling member  920  from the sub-sternal tunnel and deliver a distal portion of a medical electrical lead, for example, the distal portion of lead  16  described above in conjunction with  FIG. 1A , through a lumen of the introducer sheath to position the distal portion within the sub-sternal tunnel, for example, as shown in  FIG. 4C . According to some methods, after the distal portion of lead  16  is positioned, a proximal portion  16 - p  of lead  16  extends out from incision site IS, as illustrated in  FIG. 4B .  FIG. 4B  further illustrates multi-purpose tool  900  being positioned for inserting blunt tip  901  of alignment horn  910  through incision site IS, after detaching handle  950  from tunneling member  920 , according to some methods. The dotted-line arrow of  FIG. 4B  designates a path along which horn  910  may be advanced subcutaneously around the patient&#39;s ribcage to create the subcutaneous tunnel from incision site IS to a subcutaneous pocket P of the patient. Subcutaneous pocket P, for example, having been formed by blunt dissection through an incision  72 , lies superficial to the patient&#39;s ribcage, and is sized to hold pulse generator  14 , for example, as shown in  FIG. 4C . As was mentioned above, the pre-formed bend of horn  910  can help the operator direct blunt tip  901  around the curvature of ribcage and toward the subcutaneous pocket P. 
         [0025]    With further reference to  FIG. 4B  and according to some methods, when alignment horn  910  of tool  900  includes the open channel  917  described above in conjunction with  FIGS. 3A-B , proximal portion  16 - p  of lead  16  is advanced within channel  917  of the advanced horn  910  for positioning within the subcutaneous tunnel formed by horn  910 , so that a connector terminal  165  of lead  16  ends up in subcutaneous pocket P for coupling to pulse generator  14  via connector module  145 , as shown in  FIG. 4C . According to some embodiments, horn  910  may be detachable from handle  950  by separation from shank S 9  ( FIG. 3C ), so that, according to some alternate methods, the operator may secure lead connector terminal  165  within open channel  917 , in proximity to first end  911  of detached horn  910 , after advancing horn  910  to form the subcutaneous tunnel, and so that second end  912  of horn extends out from pocket P, and then apply a pull force to second end  912  to pull lead proximal portion  16 - p  through subcutaneous tunnel. 
         [0026]    According to some alternate methods, after alignment horn  910  forms the subcutaneous tunnel, horn  910  may be withdrawn therefrom before positioning lead proximal portion  16 - p  within the tunnel, for example, via an introducer sheath, in a similar manner to that described above for positioning the distal portion of lead  16  in the sub-sternal tunnel. 
         [0027]      FIG. 5A  is a plan view of a multi-purpose tool  500 , according to some alternate embodiments.  FIG. 5A  illustrates tool  500  including a handle  550 , an elongate tunneling member  520 , which is detachably coupled to handle  550 , and an alignment horn  510 , which has a first end  511  coupled to handle  550 , and which extends, alongside and coplanar with tunneling member  520 , from first end  511  to a second end  512  of horn  510 , being relatively straight therebetween, and parallel to a relatively straight proximal segment  521  of tunneling member  520 .  FIG. 5A  further illustrates tunneling member  520  including a blunt tip  502 , wherein a distal segment  522  of tunneling member  520  extends along a single pre-formed bend from proximal segment  521  to blunt tip  502 , such that blunt tip  502  is directed toward alignment horn  510 . According to the illustrated embodiment, tunneling member proximal segment  521  and distal segment  522  are coplanar and enclose angle β. In one example, the angle β may be between approximately 150 degrees and approximately 170 degrees. However, angles greater than 170 degrees (but less than 180 degrees) and angles less than 150 degrees (but greater than 90 degrees) may also be utilized without departing from the scope of this disclosure. Similarly, second end  512  of alignment horn  520  extends along a single pre-formed bend and is terminated by a blunt tip  501 ; and second end  512  of alignment horn  510  is coplanar with the relatively straight remainder of horn  510 , wherein an angle enclosed by second end  512  and the remainder may be similar to angle β of tunneling member  520 . In other instances, the angle of alignment horn  510  may be different than the angle β of tunneling member  520 . In other embodiments, alignment horn  510  may be relatively straight for the entire length form handle  550  to blunt tip  501 . 
         [0028]    According to some exemplary embodiments, tunneling member  520  is formed from a medical grade metal rod, such as a series  300  stainless steel rod having a diameter in a range from approximately 0.1 inch (2.5 mm) to approximately 0.14 inch (3.5 mm), for example, approximately 0.122 inch (3 mm); and the coupling between tunneling member  520  and handle  550 , which allows for the detachment of handle  550  from tunneling member  520 , may be formed by a threaded interface therebetween. Handle  550  and alignment horn  510  may each formed from a relatively hard medical grade polymer. In some alternate embodiments, tunneling member  520  may also be formed from a relatively hard medical grade polymer. 
         [0029]    With reference back to  FIG. 4A , multi-purpose tool  500  may be used in a similar fashion to that described above for tool  900  in order to create a sub-sternal tunnel by inserting blunt tip  502  of tunneling member  520  through incision site IS and then advancing tunneling member  520  in the superior direction, per arrow SUP, beneath the patient&#39;s sternum  13 , being guided by the external reference of alignment horn  510 . In  FIG. 5A  handle  550  is shown extending at an angle φ with respect to tunneling member proximal segment  521 , for example, to provide some clearance for an operator&#39;s hand while handling and manipulating tool  500  to create the substernal tunnel. Also like tool  900 , according to some methods, after forming the sub-sternal tunnel with tool  500 , the operator may detach handle  550  from tunneling member  520  to position an introducer sheath within the sub-sternal tunnel, and then position the distal portion of lead  16 , through the sheath, within the sub-sternal tunnel, as described above. Then the operator can use tool  500  to create, with alignment horn  510 , a subcutaneous tunnel from incision site IS to subcutaneous pocket P, for example, along the dashed line arrow shown in  FIG. 5B . 
         [0030]      FIG. 5A  further illustrates handle  550  including a pivot joint  551  that couples first end  511  of alignment horn  510  to handle  550  so that handle  550  may be swiveled relative to alignment horn  510 , per arrow S, for example, to the orientation shown with dashed lines, after tunneling member  520  is detached therefrom.  FIG. 5B  is a schematic showing tool  500  re-oriented (e.g., flipped 180 degrees, around a longitudinal axis of horn  510 , from the orientation of  FIG. 5A , which corresponds to sub-sternal tunneling per  FIG. 4A ) for creating the above described subcutaneous tunnel, from incision site IS to subcutaneous pocket P, after detaching tunneling member  520  from handle  550 , and swiveling handle  550 , relative to alignment horn  510 . Dashed lines in  FIG. 5A  designate an optional open channel extending along horn  510  from first end  511  to blunt tip  501 , similar to that of horn  910  of tool  900 , for example, being configured to receive insertion of lead proximal portion  16 - p  therein, to position proximal portion  16 - p  within the subcutaneous tunnel. 
         [0031]      FIGS. 6A-B  are plan views of a multi-purpose tool  600 , according to yet further embodiments.  FIGS. 6A-B  illustrate tool  600  including a handle  650 , an elongate tunneling member  620 , which has a proximal segment  621  joined to handle  650 , and an alignment horn  610 , which has a first end  611  coupled to handle  650 , and which extends, alongside and coplanar with tunneling member  620 , from first end  611  to a second end  612  of horn  610 , being relatively straight therebetween, and parallel to tunneling member proximal segment  621 .  FIGS. 6A-B  further illustrate tunneling member  620  including a blunt tip  602 , wherein a distal segment  622  of tunneling member  620  extends along a single pre-formed bend from proximal segment  621  to blunt tip  602 , such that tunneling member proximal segment  621  and distal segment  622  are coplanar and enclose an angle β, for example, which may be between approximately 150 degrees and approximately 170 degrees. However, angles greater than 170 degrees (but less than 180 degrees) and angles less than 150 degrees (but greater than 90 degrees) may also be utilized without departing from the scope of this disclosure. Tunneling member  620 , for example, formed from a medical grade metal rod, may have a diameter and length similar to that of tunneling member  920  of tool  900 ; and handle  650  and alignment horn  610  may each formed from a relatively hard medical grade polymer, or a combination of medical grade metal and polymer. In some alternate embodiments, tunneling member  920  may also be formed from a relatively hard medical grade polymer. With further reference to  FIGS. 6A-B , handle  650  of tool  600  preferably includes a looped gripping portion to accommodate various operator hand sizes, with finger recesses  653  formed therein. Handle  650  may further include an adjustment mechanism like that described above, in conjunction with  FIGS. 3A and 3C , for handle  950  of tool  900 , which allows an operator to move alignment horn  610  into a plurality of positions relative to tunneling member  620 , according to different sizes of patients, while maintaining the parallel orientation therebetween. Although an example adjustment mechanism is illustrated in  FIGS. 6A and 6B  for exemplary purposes, other adjustment mechanisms may be used in handle  650 , including some of those described elsewhere herein. 
         [0032]    According to the illustrated embodiment, handle  650  further includes a lock-and-release mechanism, for example, like that described above for handle  950  of tool  900  ( FIG. 3A ), which forms a junction between handle  650  and proximal segment  621  of tunneling member  620 , and which includes lever  952 . When lever  952  of the lock-and-release mechanism is lifted or rotated, per arrow R, handle  650  can be detached from tunneling member  620 , or tunneling member  620  rotated relative to handle  650 , around a longitudinal axis  6  thereof (defined by tunneling member proximal segment  621 ), for example, from a first position ( FIG. 6A ) to a second position ( FIG. 6B ). Although a specific lock and release mechanism is illustrated in  FIGS. 6A and 6B  for exemplary purposes, other lock and release mechanisms may be used in handle  650 , including some of those described elsewhere herein. 
         [0033]      FIG. 6A  shows tunneling member  620  in the first position, at which distal segment  622  extends toward alignment horn  610 , so that tool  600  may be used by an operator to create the above-described sub-sternal tunnel. Alignment horn  610 , as an external reference, guides the operator in the superior and sub-sternal advancement of tunneling member blunt tip  602  to create the sub-sternal tunnel, and the pre-formed bend of tunneling member  620  causes blunt tip  602  to ride adjacent the underside of sternum  13  during the superior advancement thereof when tunneling, for example, as illustrated in the schematic of  FIG. 7A .  FIG. 6B  shows tunneling member  620  having been rotated 180 degrees from the first position to the second position, at which distal segment  622  extends directly away from alignment horn  910 , so that tool  600  may be used by the operator to create the above-described subcutaneous tunnel, with the pre-formed bend of tunneling member  620  oriented to guide blunt tip  602  around the curvature of the patient&#39;s ribcage and toward the subcutaneous pocket P, for example, as illustrated by the schematic of  FIG. 7B . 
         [0034]    According to some methods, once the sub-sternal tunnel is created, the operator may detach handle  650  from tunneling member  620  to pass an introducer sheath over tunneling member  620  and into the sub-sternal tunnel, so that, when tunneling member  620  is withdrawn from the tunnel, lead distal portion can be advanced through the introducer sheath for positioning in the sub-sternal tunnel.  FIG. 7B  illustrates lead proximal portion  16 - p  extending out from incision site IS, after the lead distal portion has been positioned in the sub-sternal tunnel, and tunneling member  620  of tool  600  having been rotated to the second position, such that distal segment  622  extends directly away from alignment horn  910 .  FIG. 7B  further illustrates blunt tip  602  of tunneling member  620  directed for insertion into incision site IS to create the subcutaneous tunnel, for example, along the dashed line arrow. 
         [0035]    Once the subcutaneous tunnel from incision site IS to pocket P is formed, the operator may detach handle  650  from proximal segment  621  of tunneling member  620 , as shown in  FIG. 7C .  FIG. 7C  illustrates distal segment  622  of tunneling member  620  protruding out through incision  72 , which corresponds to subcutaneous pocket P, and a proximal end  61  of tunneling member proximal segment  621  protruding from incision site IS and being configured for attachment of lead connector terminal  165  thereto, for example, by insertion per arrow C. According to some methods, the operator may configure tunneling member proximal end  61  by securing an elastic tube  760  to proximal segment  621  of tunneling member  620  after detaching handle  650  therefrom, for example, as shown in  FIG. 7D .  FIG. 7D  is a longitudinal cross-section through the secured tube  760  that forms proximal end  61 , wherein lead connector terminal  165  is shown inserted therein for attachment to tunneling member  620 . According to the illustrated embodiment, tube  760  has an inner diameter ID that forms an interference fit around tunneling member proximal segment  621  and lead connector terminal  165 , and tube  760  may be formed from medical grade silicone rubber, for example, by an extrusion process. According to an exemplary embodiment, tube inner diameter ID is approximately 0.094 inch (2.4 mm) and a length L of tube  760  is may be as short as approximately one inch (2.5 cm) and as long as up to approximately 10 inches (25 cm). Once lead connector terminal  165  is attached to tunneling member  620 , the operator may grasp distal segment  622  of tunneling member  620  and apply a pull force thereto to withdraw an entirety of tunneling member  620  from the subcutaneous tunnel, through incision  72 , which pulls lead proximal portion  16 - p  into the tunnel so that connector terminal  165  extends into pocket P. Then, after withdrawing connector terminal  165  from tubing  760 , the operator can couple connector terminal  165  to pulse generator  14 , as described above and shown in  FIG. 4C . 
         [0036]    According to some additional embodiments, tunneling member  620  of tool  600  includes an open channel, extending along an entirety of the length, or extending just along proximal segment  621 . In these embodiments, the channel of tunneling member  620  may have a configuration similar to any of those described above for channel  917  of alignment horn  910  in tool  900  ( FIG. 3B ), for example, to accommodate the attachment of lead proximal portion  16 - p  to tunneling member  620 , as an alternative to the above-described proximal end  61 . According to some alternate methods, after the operator creates the sub-sternal tunnel with tunneling member  620  of tool  600 , which does not have an open channel, the operator may exchange tunneling member  620  for another tunneling member that has an open channel (like any embodiment of channel  917  described above) to create the subcutaneous tunnel. 
         [0037]    In the foregoing detailed description, various tool features have been described with reference to specific embodiments. However, it may be appreciated that various modifications and changes can be made without departing from the scope of the invention as set forth in the appended claims. For example, one or more features of a particular exemplary embodiment may be employed by other exemplary embodiments in the same or alternative forms. Additionally, in alternative embodiments of the methods described in  FIGS. 4, 5 and 7 , the multi-purpose implant tool may be used to form the subcutaneous tunnel first (e.g., from either incision IS to pocket  72  or from pocket  72  to incision IS) and place the proximal portion of the lead, e.g., proximal portion  16 - p  of lead  16 , within the subcutaneous tunnel and then be used to form the substernal tunnel and place the distal portion of the lead within the substernal space.