Abstract:
An implantable medical system for implantation within the body of a patient is provided. The system includes an implanted device having an implant casing and a long range telemetry sub-system housed therein. The system also includes an implantable lead operationally coupled to the implanted device and an antenna coupled to the implant casing to extend therefrom. The antenna is operationally coupled to the long-range telemetry sub-system to enable wireless bi-directional communication between the long range telemetry sub-system and predetermined external equipment disposed outside the body of the patient.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a Divisional Patent Application of co-pending application Ser. No. 10/994,466, filed on 23 Nov. 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to the field of medical devices implantable within a human patient and having the ability to communicate with remote equipment.  
       BACKGROUND OF THE INVENTION  
       [0003]     Known implantable devices including pacemakers and Implantable Cardiac Defibrillators (ICDs) include the capability to communicate with remote equipment while implanted in the body of a patient. Such communication occurs by means of an antenna of the remote equipment placed within inches of the implant to be able to reliably send and receive data to/from that implant. Recently, Biotronik Company has developed a long range telemetry system for pacemakers that allows data from the pacemakers to be transmitted to a remote receiver disposed several meters away from the patient. However, the Biotronik long range data communication system is unidirectional, meaning that data are transmitted in one direction, e.g., only from the implant to the remote receiver. This precludes error checking and such other useful functions as device programmability without employing a separate near field antenna.  
         [0004]     U.S. Pat. No. 6,609,023 issued to Fischell, et al., describes a two-way long range data communication system for data transmission between an implanted cardiac event detection system and remote equipment in both directions. In the Fischell, et al.&#39;s system, data transmission from the remote equipment to the implant is enabled by the implant turning ON its telemetry sub-system at regular intervals to “listen” for the data to be received. Such telemetry sub-systems, for example, the CC 1000  chipset from CHIPCOM, consume significant power during the “listening” phase of their operation. In order to save power and to extend the operational life of the implant, such intervals for “listening” for the data to be received are kept on the order of 30 seconds or longer. This precludes fast time response of the implanted devices to commands from the remote equipment.  
         [0005]     Since a telemetry antenna is an essential part of a medical implantable system, specific arrangements have been developed to improve the operational characteristics of implantable medical devices. For example, U.S. Pat. No. 5,342,408 describes a telemetry system for an implantable cardiac device in which a telemetry antenna is placed in a plastic header of an implanted cardiac device to facilitate high speed communication between external equipment, such as an external programmer, and the cardiac implant device. Another U.S. Pat. No. 5,456,698 describes a pacemaker in which a telemetry antenna is placed in a plastic outer casing (or “shroud”) of the implant. Yet another arrangement is shown in U.S. Pat. No. 6,614,406 wherein an antenna is placed in an antenna compartment made of a dielectric material extending from the header to wrap circumferentially around a curved portion of the device housing. U.S. Pat. Nos. 4,543,955 and 5,058,581 describe body implantable devices which use their respective leads as a telemetry antenna for the implantable device.  
         [0006]     None of the above arrangements is ideal, for the placement of a telemetry antenna in the header or a plastic outer casing of the implant limits the usable antenna length, while employing a lead of the implant as the antenna causes RF energy to be delivered into the heart. Although the Fischell&#39;s AMI detection implant described in U.S. Pat. No. 6,609,023 only requires a unipolar lead, the device is typically implanted with a standard bipolar pacemaker lead so that if a pacemaker is needed by the patient, no new lead needs to be implanted. Using a second conductor in the lead as the antenna is not desirable as it also has the negative effect associated with delivering RF energy into the heart.  
         [0007]     It would be therefore highly desirable to realize an implantable medical system free of these and other shortcomings of prior implantable devices.  
       SUMMARY OF THE INVENTION  
       [0008]     It is therefore an object of the present invention to provide a system including an implanted medical device (implant) and an external transceiver between which long range two-way data communication may be effected. In accordance with the present invention, factors such as antenna location, antenna configuration, and remote electromagnetic signaling to the implant to turn ON/OFF the long range telemetry sub-system are advantageously combined.  
         [0009]     It is another object of this invention to provide an implantable medical device with long range telemetry where the antenna is positioned in a connecting cable located between a device casing and an implantable lead of the device.  
         [0010]     An additional object of the present invention is to provide an implantable medical device with long range telemetry where an antenna may be located outside of the device casing and provided with its own feed through the casing.  
         [0011]     Still another object of this invention is to provide an implantable medical device with long range telemetry where the antenna is located in close proximity (outside, inside or within) to a window made from a non-conductive material placed in the casing of the implant.  
         [0012]     Yet another object of the present invention is to provide an implantable medical device with long range telemetry where the device includes a magnetic switch function to enable two-way long range telemetry.  
         [0013]     Yet another object of the present invention is to provide an implantable medical device with long range telemetry where the device has a near field (&lt;200KHz) electromagnetic sensor for enabling two-way long range telemetry when external equipment placed within 6 inches or closer proximity of the implanted device sends an appropriate low power electromagnetic signal to the implant.  
         [0014]     It is an additional object of the present invention to provide an implantable medical device with long range telemetry where the implant has a near field (&lt;200KHz) electromagnetic sensor for enabling two-way long range telemetry when external equipment located more than 6 inches away from the implant sends an appropriate high power electromagnetic signal.  
         [0015]     Still another object of the present invention is to provide an implantable medical device having an antenna which is arranged as the proximal section of one of the conducting wires of a modified pacemaker lead and where a connecting module within the lead connects the proximal section of the wire to the distal section of the wire for use with a pacemaker or Implantable Cardiac Defibrillator (ICD).  
         [0016]     In one embodiment of the antenna configuration, a multi-conductor connecting cable is located between a header of the implant casing and an implantable lead. In the connecting cable, one conductor is used as the antenna, while the other conductors are used for connection to the lead. The proximal end of such a connecting cable may either connect through feed-throughs directly to the electronic circuitry of the implant or attach to a standard implantable device header. The distal end of the connecting cable includes measures for connecting to an implantable lead.  
         [0017]     In certain embodiments, such lead may be a standard bipolar pacemaker lead. One conductor of the connecting cable may then connect to one electrode of the bipolar lead, while other conductor may terminate within the connecting cable&#39;s length to serve as the antenna.  
         [0018]     In an alternate embodiment, the antenna may be located outside of the casing of the implant. This may either be in the form of a loose wire, or a wire attached to a non-conducting casing extension.  
         [0019]     In another embodiment of the antenna configuration, a non-conducting window is formed in a side wall of the implant casing with the antenna placed in close proximity to the window, the antenna may then be disposed inside the implant casing, within the window material, or attached to the window outside the implant casing.  
         [0020]     Another alternate embodiment of the system of the present invention employs a modified bipolar pacemaker lead in which a wire connected to a ring electrode is normally discontinuous at a location part way down the lead. In this state, the wire has a proximal section and a distal section which are normally displaced each from the other. The proximal section of the wire is designed to function as an antenna for the implant&#39;s telemetry sub-system. A connecting module provides for connection between the proximal and distal sections of the wire to allow the bipolar pacemaker lead to function with a standard pacemaker. This concept is applicable to any wire within any lead. For example, the connectable lead wire concept may be implemented using the tip wire in a bipolar lead or using any one of the wires in an Implantable Cardiac Defibrillator (ICD) or dual chamber pacemaker lead.  
         [0021]     To reduce power consumption in a “listening” mode of operation for receiving commands from a remote device, numerous different techniques may be used in the system of the present invention. These techniques include the use of magnetic switching, near field activation, or a remote high power signal burst activation.  
         [0022]     The use of magnetic switching is perhaps the simplest of these techniques. Most implantable devices have a magnetic switch for switching ON and OFF specific functions. In this case, placement of a magnet near the implant would cause the device to turn ON the long range telemetry receiver for a preset period of time to “listen” for long range telemetry commands. After the preset period elapses, the receiver is turned OFF to save power. The receiver may remain ON continuously during the preset period or may alternatively be switched periodically (e.g. for 100 ms every 2 seconds) during the preset time period to provide even more efficient energy saving.  
         [0023]     The near field activation technique uses a typical near field receive circuit, as is found in most pacemakers. In this case, an electromagnetic signal sent by a device held close to the implant&#39;s location will be received by the near field receive circuit which then triggers the implant to switch the long range telemetry ON for a preset period of time, either continuously or periodically.  
         [0024]     The high power burst technique sends an electromagnetic signal burst from a device located six inches or more away from the implant. The signal has sufficient intensity when received by the near field receiver circuitry in the implant to activate the long range telemetry system, much as with the near field activation technique. Specific security codes may be included in the near field activation signal or high power burst signal to minimize or eliminate the chance of inadvertently activating the long range telemetry circuitry for other signal sources.  
         [0025]     The antenna for the near field receive circuitry can either be the same as the long range telemetry antenna or it can be a separate antenna located within the header or within the casing of the implant.  
         [0026]     These and other objects and advantages of the present invention will become apparent to a person of ordinary skill in this art upon reading of the detailed description of this invention including the associated drawings as presented herein.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]      FIG. 1  schematic diagram illustrating one system embodiment of the present invention, which includes an implanted portion and an external portion communicating each with the other;  
         [0028]      FIG. 2  is a schematic block diagram of the system embodiment of an implant portion with long range telemetry in accordance with the present invention;  
         [0029]      FIG. 3A  is a side view of one embodiment of a connecting cable antenna formed in accordance with the present invention;  
         [0030]      FIG. 3B  partially cutaway side view of the embodiment shown in  FIG. 3A  illustrating a portion of the internal structure;  
         [0031]      FIG. 4  shows the embodiment of the implanted portion of the system of the present invention shown in  FIG. 3A , with the connecting cable antenna attached to a standard bipolar lead header connection;  
         [0032]      FIG. 5  shows an alternate embodiment of the implanted portion of the system of the present invention, with a loose antenna located outside of the case of the implanted portion;  
         [0033]      FIG. 6  shows another alternate embodiment of the implanted portion of the system of the present invention, with a window in the outer side of the implant casing and an antenna located in close proximity to the window;  
         [0034]      FIG. 7A  is a cross sectional view of the implanted portion of  FIG. 6  with the antenna disposed outside of the window;  
         [0035]      FIG. 7B  is a cross sectional view of the implanted portion of  FIG. 6  with the antenna disposed inside of the window;  
         [0036]      FIG. 7C  is a cross sectional view of the implanted portion of  FIG. 6  with the antenna disposed within the window;  
         [0037]      FIG. 8  shows an embodiment of the implanted portion of the system of the present invention with a permanently attached connecting cable antenna;  
         [0038]      FIG. 9  shows an embodiment of the connecting cable with an attached subcutaneous lead;  
         [0039]      FIG. 10  shows an embodiment of the antenna configuration using a connectable lead wire;  
         [0040]      FIG. 11A  is an enlarged view of the connection module within the lead of  FIG. 10  shown in the open configuration;  
         [0041]      FIG. 11B  is an enlarged view of the connection module within the lead of  FIG. 10  shown in the closed configuration;  
         [0042]      FIG. 12A  is the cross section of the connection module of  FIG. 11A  taken along line  12 A- 12 A; and  
         [0043]      FIG. 12B  is the cross section of the connection module of  FIG. 11B  taken along line  12 B- 12 B.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0044]     Regarding  FIG. 1 , an implantable medical system with long range telemetry of the present invention includes an implanted portion  10  and an external portion  20 . The implanted portion  10  includes an implanted medical device (also referred to herein as an implant)  70  having a connecting cable  60  with a lead connector  66  that attaches to a lead  18  having electrode(s)  19 . The implant  70  includes a casing  71  and a header  72 . The implant  70  may be a diagnostic device with patient alerting capability such as described by Fischell, et al. in U.S. Pat. No. 6,609,023, or it may be a therapeutic device such as a pacemaker, Implantable Cardiac Defibrillator (ICD), an implantable drug pump, or the like.  
         [0045]     The external portion  20  includes an external transceiver  25 . A battery  21  may be embedded into the external transceiver  25  which is connected to other equipment  30 . The other equipment  30  may include a physician&#39;s programmer and other display and command devices such as PDAs or cell phones. If power is provided by the other equipment  30  to the external transceiver  25  then no battery  21  is necessary. The external transceiver  25  also includes one or more control buttons  22 , long range communications circuitry  23  provided with an antenna  24 , and an electromagnetic signal generator  26  provided with an antenna  27 . These components are managed by a CPU  28  having an acoustic transducer  29  coupled thereto.  
         [0046]     A magnet  32  may also be included as a part of the external portion  20 . The magnet  32  may be arranged as a separate part, or may alternatively be integrated into the external transceiver  25 .  
         [0047]      FIG. 2  is a schematic block diagram of the implanted medial device  70  which generally includes a battery  22 , long range telemetry sub-system  46 , and an antenna  35 . A CPU  44  having a memory block  45 , in conjunction with the clock/timing sub-system  49 , controls the function of the implanted medical device  70 . Incoming signals from electrodes  14 ,  17 , and  19  are amplified by an amplifier  36 , digitized by an analog-to-digital converter  41  and temporarily stored by a FIFO buffer  42 . The implanted medical device  70  may also contain electrical stimulation circuitry  170  and/or cardiac defibrillator circuitry  180  coupled to the CPU  44  which are operable to deliver electrical stimulation to the heart through one or more electrodes, such as the electrodes  12  and  15 .  
         [0048]     Patient alerting is provided by the alarm sub-system  48  which may use vibrational, acoustic, electrical tickle or other suitable techniques to alert the patient to a specific event identified by the CPU  44 .  
         [0049]     A magnet sensor  190  permits triggering of device commands by placing the magnet  32  of  FIG. 1  in close proximity to the implant  70 . A near field electromagnetic sensor  56  with an antenna  55  is also present in the implant  70 .  
         [0050]     Current long range telemetry chip sets such as the Chipcom CC 1000  chipset or the RF Microdevices Ash hybrid consume significant power even in the “listening” mode of operation of the implant  70 . Consequently, the electromagnetic sensor  56  and/or magnet sensor  190  are the extremely important for efficient use of supplied power and significantly longer life of the battery  22  in the device of the present invention. Efficiency is heightened by an arrangement in which the long range telemetry sub-system  46  is normally turned OFF and only turned ON responsive to placement of the magnet  32  of  FIG. 1  in close proximity to the magnet switch  190  or to detection of a specific signal by the electromagnetic sensor  56 .  
         [0051]     Once activated, the long range telemetry sub-system  46  operates to “listen” continuously or intermittently for a preset period. It listens for incoming long range data communication from the long range communications circuitry  23  of the external transceiver  25  shown in  FIG. 1 . If no signal is received, the long range telemetry sub-system  46  is turned OFF to save power. For maximum power conservation, the implanted medical device  70  may activate the electromagnetic sensor  56  only on a periodic basis. For example, the long range telemetry sub-system  46  might be turned ON to listen for ½ second every 5 seconds.  
         [0052]     It is envisioned that the electromagnetic sensor  56  would be similar to the near field telemetry sub-systems present in current pacemakers and ICDs and would operate at frequencies below 200 KHz, for example, preferably in the range of 80-100 KHz. The antenna  55  may be of a suitable type known in the art, such as a simple inductive coil antenna used in current pacemakers.  
         [0053]      FIG. 3A  is a side view of the connecting cable  60  having a distal ring  61 D, proximal ring  61 P, a cable  65  and a lead connector  66  with fastening screws  67 D and  67 P. The proximal end of the connecting cable  60  is designed to be attached to the header  72  of the implanted medical device  70  as shown in  FIG. 1 .  
         [0054]      FIG. 3B  illustrates the details of the internal structure of the connecting cable  60 . The proximal ring  61 P connects through a conductor  62  to a proximal contact  63  in the lead connector  66  of the connecting cable  60 . The fastening screw  67 P secures one of the conductors for a bipolar lead, such as the lead  18  of  FIG. 1 , against the proximal contact  63 . The distal ring  61 D connects to the antenna wire  64  which terminates at a predetermined distance from distal ring  61 D in a manner appropriate for the frequencies of the signals to be transmitted and received by the antenna wire  64 . In this embodiment, the antenna wire  64  acts as either or both of the antennas  35  and  55  shown in  FIG. 2 .  
         [0055]     The proximal fastening screw  67 P secures the proximal ring of an attachable bipolar lead to the proximal contact  63 . Although no connection is shown between either of the rings  61 D or  61 P of the connecting cable  60  and the distal contact  69 , it is envisioned that if a third ring is added to the distal end of the connecting cable  60 , then both poles of a bipolar lead may be connected through to the implanted medical device  70  that would then require three contacts in its header  72  (one for the antenna wire  64  and two for both poles of a connected bipolar lead).  
         [0056]      FIG. 4  shows the implanted portion  10  of the implantable system of the present invention where the connecting cable  60  couples to a standard bipolar lead header  72  attached to the casing  71  of the implant  70 . As in most such implants, the conductors  75  and  76  in the header  72  connect to the electronics inside the casing  71  via the feed-throughs  73  and  74 , respectively. The conductor  75  connects at its distal end to the contact  78 D that will be pressed against the distal ring  61 D of the connecting cable  60  when an adjustable member such as a set screw  77 D is tightened. Similarly, the conductor  76  connects at its distal end to the contact  78 P that will be pressed against the proximal ring  61  P of the connecting cable  60  when an adjustable member such as a screw  77 P is tightened.  
         [0057]      FIG. 5  illustrates an alternate embodiment of the implant  80  of the present invention wherein a loose antenna  85  located outside of a casing  81  is employed. The implant  80  includes the casing  81  and a header  82 , and is coupled directly to a bipolar lead  18  with respective distal and proximal rings  17 D and  17 P. The loose antenna  85  connects through the header  82  and a feed through  83  to circuitry inside the casing  81  of the implant  80 . A conductor  86  connects a contact  88 P to a feed through  84  which also connects to circuitry inside the casing  81  of the implant  80 . A set screw  87 P is provided as shown, which when tightened, presses the contact  88 P against the proximal ring  17 P of the lead  18 . Another set screw  87 D is provided as shown, which when tightened, presses a contact  88 D against the distal ring  17 D of the lead  18 . Although, in  FIG. 5 , the contact  88 D is not connected by a feed through to circuitry inside the casing  81  of the implant  80 , a third feed through and conductor may be added for this contact in accordance with another aspect of the present invention.  
         [0058]      FIG. 6  illustrates still another embodiment of the implant  90  of the present invention with a window  89  made of non-conducting material disposed at an outer side of the implant casing  91 . An antenna  99  is located in close proximity to the window  89 . The implant  90  with the casing  91  and a header  92  connects directly to a bipolar lead  18  with respective distal and proximal rings  17 D and  17 P. A conductor  96  connects a contact  98 P to a feed through  94  which connects to circuitry inside the casing  91  of the implant  90 . A set screw  97 P is provided, which when tightened, presses the contact  98 P against the proximal ring  17 P of the lead  18 . Likewise, a conductor  95  connects a contact  98 D to a feed through  93  which also connects to circuitry inside the casing  91  of the implant  90 . A set screw  97 D is provided, which when tightened, presses the contact  98 D against the proximal ring  17 D of the lead  18 .  
         [0059]      FIG. 7A  is a cross sectional view of an embodiment of the implant  90  shown in  FIG. 6 , taken along line  7 - 7  thereof. In this particular embodiment, the window  89 A is formed as shown in a side wall of the casing  91 . The antenna  99 A is positioned inside of that window  89 A, bearing against an inner surface thereof. The antenna  99 A connects to extend from the long range telemetry circuitry  46 .  
         [0060]      FIG. 7B  is a cross sectional view of another embodiment of the implant  90  shown in  FIG. 6 , taken along line  7 - 7  thereof. In this alternate embodiment, the window  89 B is again formed in a side wall of the casing  91 . The antenna  99 B is positioned within that window  89 B to be at least partially embedded therein. The antenna  99 B connects to extend from the long range telemetry circuitry  46 .  
         [0061]      FIG. 7C  is a cross sectional view of still another embodiment of the implant  90  shown in  FIG. 6  taken along line  7 - 7  thereof. Here, the antenna  99 C is disposed outside of the window  89 C which is, again, formed in a sidewall of the casing  91 . The antenna  99 C extends along an outer surface of the window  89 C, and connects by a feed-through  19  formed in the casing  91  to the long range telemetry circuitry  46 .  
         [0062]      FIG. 8  illustrates yet another embodiment of the implanted system  100  of the present invention wherein an integrated connecting cable  108  is employed. The implant  100  includes a casing  101  and a header  102 . An antenna  105  is provided within the integrated connecting cable  108  itself, and connects via a feed-through  103  to circuitry inside the case  101 . A proximal end of the connecting cable  108  may be formed much like that of the connecting cable  60  shown in  FIGS. 3A and 3B . A proximal end of the conductor  106  connects to the lead contact  63  at the proximal section of the integrated connecting cable  108  in much the same manner that conductor  62  does in  FIG. 3B . A distal end of the conductor  106  connects via a feed-through  104  to circuitry inside the casing  101  of the implant  100 . An advantage of this implant  100  embodiment over the embodiments employing attachable connecting cables is that the integrated connecting cable  108  affords a smaller header  102  than the connectable connecting cable  60  of  FIGS. 3A, 3B , and  4 , for instance. This allows for either a smaller overall implant or for increased space within the casing to accommodate device electronics and battery.  
         [0063]      FIG. 9  shows the connecting cable  60  of  FIGS. 3A, 3B , and  4  formed with an attached subcutaneous lead  120 , the subcutaneous lead  120  preferably includes a conductor  124  which connects a distal ring  122  with an electrode  126 .  
         [0064]      FIG. 10  shows a modified bipolar lead  160  formed in accordance with yet another embodiment of the present invention. The bipolar lead  160  preferably includes a standard proximal end with proximal ring  161 P and distal ring  161 D. The proximal ring  161 P is connected to a wire  162  whose free end terminates at a tip electrode (not shown) for the bipolar lead  160 . The distal ring  161 D is connected to a proximal conducting wire  164  whose free end terminates at a connecting module  170 . A distal connecting wire  165  extends from the connecting module  170  to terminate at a ring electrode (not shown) for the bipolar lead  160 . Known distal tip configurations of bipolar leads include those manufactured and sold by St. Jude Medical, Guidant or Medtronic.  
         [0065]     The connecting module  170  preferably serves to connect a proximal lead body  166  and a distal lead body  168 . In the configuration of  FIG. 10 , the proximal wire  164  is detached from the distal wire  165 . This allows the proximal wire  164  to function as an antenna of length “L” for an implanted device such as the device of  FIG. 4 . The proximal wire  164  has a length “L” that is preferably optimized for operation in the particular RF communication frequency range intended for the implanted device&#39;s telemetry sub-system  46 , such as shown in  FIG. 2 . The length L is preferably set between 1 and 6 inches in approximate length. An advantage of the embodiment illustrated in  FIG. 10  is that there is no need for a separate multi-wire connecting cable  60  of the type shown in  FIG. 9  to avoid delivering energy from the antenna into the heart. The embodiment of  FIG. 10  also allows reconfiguration of the lead  160  to serve as a bipolar lead adapted for a pacemaker or ICD. Although this embodiment is shown for a bipolar lead having two electrodes, a connecting module  170  may be used in accordance with alternate embodiments of the present invention to accommodate a lead having three or more electrodes.  
         [0066]      FIG. 11A  shows on an enlarged scale the connection module  170  of  FIG. 10  connecting the proximal lead body  166  and distal lead body  168 . The wire  162  passes through the connection module  170 . The connection module  170  preferably include a main body  172 , an elastomer sealing sheath  178  and a set screw  175 . The set screw may be advanced using any suitable means known in the art, such as an Allen (hex) type wrench (not shown). In  FIG. 11A , a distal end  174  of the proximal wire  164  and a proximal end  176  of the distal wire  165  are, detached from each other separated by a distance “D.”
         FIG. 11B  shows on an enlarged scale the connection module  170 ′ of  FIG. 10  upon reconfiguration of the lead  160  to a bipolar lead configuration. The reconfiguration utilizes suitable connecting measures for connecting the proximal wire  164  to the distal wire  165 . Suitable connecting measures may be used, for example, to reconfigure the lead in the following manner:     1. cutting the elastomer sealing sheath with a scalpel to produce the slit  177 ;     2. inserting an Allen (hex) or other suitable type wrench through the slit to engage set screw  175  or other adjustable member (by insert into a hexagonal opening formed in a top of the set screws, for instance);     3. advancing the set screw to depress the proximal end  176 ′ of the distal wire  165  so that it contacts the distal end  174  of the proximal wire  164 ; and,     4. resealing the elastomer sealing sheath  178  using silicone or another plastic substance that will harden after injection through the slit  177 .          
         [0072]     Suitable variations of these measures may be employed. For instance, instead of cutting and resealing the sheath  178 , a self-sealing slit may be used.  
         [0073]      FIG. 12A  is a cross sectional view of the connection module  170  of  FIG. 11A  taken along line  12 A- 12 A thereof and showing the junction of the proximal lead body  166  and the distal lead body  168 . The wire  162  passes through the connection module  170 . The connection module  170  preferably includes a main body  172 , an elastomer sealing sheath  178  and a set screw  175 . The set screw is preferably formed with a hexagonal opening  179  at its top. The distal end  174  of the proximal wire  164  and the proximal end  176  of the distal wire  165  in this configuration remain detached from each other.  
         [0074]      FIG. 12B  is a cross sectional view of the connection module  170 ′ of  FIG. 11A  taken along line  12 A- 12 A thereof upon reconfiguration of the lead  160  to its bipolar lead configuration. As described, the reconfiguration involves a connecting measure for connecting the proximal wire  164  to the distal wire  165 . The final step ( 4 ) in the illustrative reconfiguration process described results in resealing the elastomer sealing sheath  178  with preferably a plastic substance  173  which substantially fills the slit above the set screw  175 .  
         [0075]     While the set screw  175  mechanically pushes the proximal end  176  of the distal wire  165  to make or break connection with the distal end  174  of the proximal wire  164 , other alternate techniques may be employed in accordance with the present invention. For example, turning the set screw may extend a telescopic piece that connects the ends  174  and  176 . Another alternate mechanism may be of the “fastener” type often used in assembling shelving units where one half turn locks or unlocks the “fastened” connection.  
         [0076]     In accordance with yet another alternate embodiment of the present invention, an indicator may be used to show the state (connected or detached) of the lead wire connection. Such an indicator may change color, much as in the strip closures used in plastic bags, or may employ specific marks to visually indicate the state of lead wire connection.  
         [0077]     Although  FIGS. 10-12B  illustrate a specific exemplary arrangement for pushing together the proximal and distal wires  164  and  165 , numerous other suitable arrangements may be employed in accordance with the present invention. For example, a system may be used where a predefined rotational motion causes the wires to align and connect. In another example, a predefined bending motion causes the wires to align and connect.  
         [0078]     Various other modifications, adaptations, and alternate configurations are of course possible in light of the teachings of the present invention presented above. Therefore, it should be understood at this time that, within the scope of the appended Claims, the invention may be practiced otherwise than as specifically described herein.