Patent Publication Number: US-2022233846-A1

Title: Implantable medical lead devices and systems having balanced clocked conductor positions

Description:
TECHNICAL FIELD 
     Embodiments relate to implantable medical lead devices and systems that include conductors having balanced clocked conductor positions. 
     BACKGROUND 
     Implantable medical systems provide medical therapy by producing electrical stimulation signals that are delivered to a target site within the body. An implantable stimulation device that produces the electrical stimulation signals is typically implanted at a location of convenience within the body of the patient that is capable of accommodating the physical size of the device. This implantation location of the implantable stimulation device may be at some distance from the target stimulation site within the body. Therefore, an implantable medical lead device is also implanted to deliver the electrical stimulation signals to the target site. 
     The implantable medical lead device may take various forms. For instance, for a relatively shorter distance from the implantable medical device to the target stimulation site, the implantable medical lead device may be an implantable medical lead. The implantable medical lead has a proximal end that couples to the implantable stimulation device and a distal end that has electrodes and that is located at the target site to deliver the electrical signals from the electrodes to the target site. For a relatively longer distance from the implantable medical device to the target stimulation site that exceeds the reach of an implantable medical device alone, multiple implantable medical lead devices may be included. A first implantable medical lead device in the form of an implantable medical lead extension may be coupled between a second implantable medical lead device in the form of the implantable medical lead and the implantable stimulation device. The implantable medical lead extension has proximal end that couples to the implantable stimulation device and a distal end that includes a distal housing that couples to the proximal end of the implantable medical lead. The implantable medical lead extension carries the electrical stimulation signals between the implantable stimulation device and the implantable medical lead. 
     In either case, the proximal end of the implantable medical lead device is inserted into a lead bore of the implantable stimulation device in order to couple electrical connectors on the proximal end to electrical contacts within the lead bore. This can present a challenge for conventional implantable medical lead devices that are created by using injection molding to form the lead body at the proximal end where the proximal contacts are located. Due to conventional conductor routing within the implantable medical lead device, the injection molding may result in a curvature of the proximal end that complicates the insertion of the proximal end into the lead bore. 
     SUMMARY 
     Embodiments address issues such as these and others by providing implantable medical lead devices that include balanced clocked conductor positions. Examples of balance clocked conductor positions include at least one pair conductors of a similar length as measured from a given longitudinal location along the lead to the respective electrical connectors coupled to the conductors where the at least one pair of conductors are in clocked positions within the body of the lead so that the angle of separation between them is greater than 135 degrees. Other examples of balanced clocked conductor positions include at least one pair of conductors of a similar length as measured from a given longitudinal location along the lead to the respective electrical connectors coupled to the conductors where the at least one pair of conductors are in clocked positions within the body of the lead so that the angle of separation between them is equal to at least a quantity equal to 180 degrees less a second quantity equal to 360 degrees divided by a total number of conductors present within the lead device body. These balanced clocked conductor positions assist in reducing the tendency of the end of the implantable medical device to become curved due to injection molding. Clocked positions in general as used herein refer to positions spaced around a looped layout such as circular, elliptical, and the like. 
     Embodiments provide an implantable medical lead device that includes a lead device body and at least four proximal electrical connectors located on a proximal end of the lead device body and separated longitudinally. The implantable medical lead device further includes at least four distal electrical connectors located on a distal end of the lead device body and at least four conductors within the lead device body. Each conductor of the at least four conductors interconnects a corresponding proximal electrical connector of the at least four electrical proximal connectors to a corresponding distal electrical connector of the at least four distal electrical connectors. Each of the at least four conductors has a length as measured from a given longitudinal position along the lead device body where the at least four conductors are present to the corresponding proximal electrical connector of each conductor. The length of a first conductor of the at least four conductors is most similar among the at least four conductors to the length of a second conductor of the at least four conductors. The first conductor and the second conductor are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least 135 degrees. 
     Embodiments provide an implantable medical system that includes an implantable medical stimulator device that includes a header having a lead bore and electrical contacts within the lead bore. The implantable medical system includes an implantable medical lead device that includes a lead device body. At least four proximal electrical connectors are located on a proximal end of the lead device body and are separated longitudinally. The proximal end being located within the lead bore such that the at least four proximal electrical connectors are in contact with corresponding electrical contacts present within the lead bore. At least four distal electrical connectors are located on a distal end of the lead device body, and at least four conductors are within the lead device body. Each conductor of the at least four conductors interconnects a corresponding proximal electrical connector of the at least four proximal electrical connectors to a corresponding distal electrical connector of the at least four distal electrical connectors. Each of the at least four conductors has a length as measured from a given longitudinal position along the lead device body where the at least four conductors are present to the corresponding proximal electrical connector of each conductor. The length of a first conductor of the at least four conductors is most similar among the at least four conductors to the length of a second conductor of the at least four conductors. The first conductor and the second conductor are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least 135 degrees. 
     Embodiments provide an implantable medical lead device that includes a lead device body and at least five proximal electrical connectors located on a proximal end of the lead device body and separated longitudinally. At least five distal electrical connectors are located on a distal end of the lead device body, and at least five conductors are within the lead device body. Each conductor of the at least five conductors interconnects a corresponding proximal electrical connector of the at least five proximal electrical connectors to a corresponding distal electrical connector of the at least five distal electrical connectors. Each of the at least five conductors has a length as measured from a given longitudinal position along the lead device body where the at least five conductors are present to the corresponding proximal electrical connector. The length of a first conductor of the at least five conductors is most similar among the at least five conductors to the length of a second conductor of the at least five conductors. The first and second conductors are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least a quantity equal to 180 degrees less a second quantity equal to 360 degrees divided by a total number of conductors present within the lead device body. 
     Embodiments provide an implantable medical system that includes an implantable medical stimulation device that includes a header having a lead bore and electrical contacts within the lead bore. The implantable medical system includes an implantable medical lead device that includes a lead device body and at least five proximal electrical connectors located on a proximal end of the lead device body and separated longitudinally. The proximal end is located within the lead bore such that the at least five proximal electrical connectors are in contact with corresponding electrical contacts present within the lead bore. At least five distal electrical connectors are located on a distal end of the lead device body and at least five conductors are within the lead device body. Each conductor of the at least five conductors interconnects a corresponding proximal electrical connector of the at least five proximal electrical connectors to a corresponding distal electrical connector of the at least five distal electrical connectors. Each of the at least five conductors has a length as measured from a given longitudinal position along the lead device body where the at least five conductors are present to the corresponding proximal electrical connector of each conductor. The length of a first conductor of the at least five conductors is most similar among the at least five conductors to the length of a second conductor of the at least five conductors. The first conductor and the second conductor are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least a quantity equal to 180 degrees less a second quantity equal to 360 degrees divided by a total number of conductors present within the lead device body. 
     Embodiments provide a method of providing an implantable medical lead device that involve providing a lead device body and providing at least four proximal electrical connectors located on a proximal end of the lead device body and separated longitudinally. The method further involves providing at least four distal electrical contacts located on a distal end of the lead device body and inserting at least four conductors within the lead device body. Each conductor of the at least four conductors interconnects a corresponding proximal electrical connector of the at least four proximal electrical connectors to a corresponding distal electrical connector of the at least four distal electrical connectors. Each of the at least four conductors have a length as measured from a given longitudinal position along the lead device body where the at least four conductors are present to the corresponding proximal electrical connector of each conductor. The length of a first conductor of the at least four conductors is most similar among the at least four conductors to the length of a second conductor of the at least four conductors. The first conductor and the second conductor are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least 135 degrees. 
     Embodiments provide a method of providing an implantable medical lead device that involves providing a lead device body and providing at least five proximal electrical connectors located on a proximal end of the lead device body and separated longitudinally. The method further involves providing at least five distal electrical connectors located on a distal end of the lead device body and inserting at least five conductors within the lead device body. Each conductor of the at least five conductors interconnects a corresponding proximal electrical connector of the at least five proximal electrical connectors to a corresponding distal electrical connector of the at least five distal electrical connectors. Each of the at least five conductors has a length as measured from a given longitudinal position along the lead device body where the at least five conductors are present to the corresponding proximal electrical connector of each conductor. The length of a first conductor of the at least five conductors is most similar among the at least five conductors to the length of a second conductor of the at least five conductors. The first conductor and the second conductor are clocked in positions that provide an angular separation between the first conductor and the second conductor of at least a quantity equal to 180 degrees less a second quantity equal to 360 degrees divided by a total number of conductors present within the lead device body. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example of an implantable medical system including a proximal end of an implantable medical lead device. 
         FIG. 2  shows a distal end of an implantable medical lead. 
         FIG. 3  shows a distal end of an implantable medical lead extension connected to a proximal end of the implantable medical lead. 
         FIG. 4  shows an end of the implantable medical lead device and illustrates the example of balanced clocked conductor positions 
         FIG. 5  shows a cross-sectional view taken laterally through the implantable medical lead device that further demonstrates the example of balanced clocked conductor positions. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments provide implantable medical lead devices such as leads and lead extensions that include conductors with balanced clocked positions that reduce the tendency of the end of the lead to curve upon being injection molded. One or more pairs of conductors of similar length as measured from a point of reference to the end of the conductors of the pair are arranged to be in balanced clocked positions within the lead. Embodiments provide various examples of balanced clocked conductor positions, such as maintaining at least 135 degrees of separation of the balanced clocked conductor positions of the two conductors of the pair in one example. As another example, embodiments may maintain a separation of the balanced clocked conductor positions of the two conductors of the pair by at least a quantity equal to 180 degrees less one average clocked position separation, where the average clocked position separation may be found as a second quantity equal to 360 degrees divided by the number of conductors that are present within the lead device. 
     An example of an implantable medical device system  100  that may include embodiments of the balanced clocked conductor positions of an implantable medical lead device  104  is shown in  FIG. 1 . The implantable medical system  100  includes an implantable medical stimulation device  102 . In this example, the implantable medical stimulation device  102  includes a housing  106  that includes stimulator circuitry  107  that produces the electrical stimulation signals. The implantable medical stimulation device  102  of this example also includes a header  108  mounted atop the housing  106 , where the header  108  includes a lead bore  110  with opening  116  where the proximal end  118  (if lead device  104  is a lead extension),  118 ′ (if lead device  104  is a lead) of lead device  104  is inserted. 
     Electrical stimulation signals from the stimulator circuitry  107  travel inside the housing  107  to electrical contacts  112  in the lead bore  110  of the header  108 . An electrically conductive path  114  for the electrical stimulation signals is provided for each output channel of the stimulator circuitry  107 . The housing may be hermetically sealed to prevent fluids from entering the housing  106 , and in that case, the electrically conductive path may include a hermetic feedthrough where the path  114  transitions from inside the housing  106  to inside the header  108 . The path  114  for each channel of the stimulator circuitry  107  continues to corresponding electrical contacts  112 . 
     Once the proximal end  118 ,  118 ′ of the implantable medical lead device  104  is fully inserted into the lead bore  110 , proximal electrical contacts  120  (if lead device  104  is a lead extension),  120 ′ (if lead device  104  is a lead) in the form of rings in this example come into physical contact with the electrical connectors  112 . Electrical conductors within the body  105  of the lead device  104  and electrically connected to corresponding connectors  120 ,  120 ′ then carry the stimulation signals to the distal end of the lead device  104 . The body  105  may be constructed of biocompatible materials including various polymers such as polyurethane and the like to provide flexibility while also providing protection of the conductors from external conditions. 
     The example of  FIG. 1  shows a total of eight separate conductive paths, eight separate contacts, and eight separate connectors. It will be appreciated by one of ordinary skill in the art that the number of conductive paths, contacts, and connectors may vary from those shown in  FIG. 1  while still implementing balanced clocked conductor positions within the lead device  104 . 
       FIG. 2  shows an example of a distal end  202  of an implantable medical lead  200 , which is an example of the implantable medical lead device  104  of  FIG. 1 . The distal end includes distal electrical connectors  204  in the form of ring electrodes that are electrically coupled to the distal portion  206  of conductors within the lead  200 . The lead  200  is implanted so that the distal electrodes  204  are positioned at the target stimulation site within the body of the patient to deliver the electrical stimulations signals. While the distal portion  206  of the conductors are shown as approaching the electrodes in a stair-stepped manner, it will be appreciated by those of ordinary skill in the art that the conductors of the distal end  200  may instead be in the same balanced clocked positions as the conductors at the proximal end  118 ′ of the lead  200  as discussed in detail below in relation to  FIGS. 4-6 . Indeed, if the conductors  206  maintain the same position as the balanced clocked positions of the proximal end  118 ′ of the lead  200  and the distal electrodes are order in the same manner as the proximal connectors  120 ′, then the distal portion of the conductors  206  will also be in balanced clocked positions. 
       FIG. 3  shows an example of a distal end  301  of an implantable medical lead extension  300 , which is an example of the implantable medical lead device  104  of  FIG. 1 . The distal end  301  includes a distal housing  302  that contains distal contacts  306  within a lead bore  310 . The distal contacts  306  are electrically coupled to a distal portion  308  of conductors within the lead extension  300 . 
     The lead extension  300  is implanted so that the distal end  301  is positioned at location of convenience for receiving the proximal end  118 ′ of the implantable medical lead  200  into the lead bore  310  through an opening  304  in the housing  302 . The proximal connectors  120 ′ of the lead  200  physically engage distal electrical connectors  306  of the lead extension  300  that are located within the lead bore  310  and take the form of electrical contacts. This effectively extends the pathway from the electrical connectors  112  of the implantable stimulation device  102  from  FIG. 1  to the distal electrodes  204  of the lead  200  of  FIG. 2 . 
     In this example shown in  FIG. 3 , balanced clocked conductors may be present in the proximal end  118  of the embodiment of the implantable medical lead extension  300  to reduce the tendency of curvature in the proximal end  118  to aid in the insertion of the proximal end  118  into the lead bore  110  of the implantable medical stimulation device  202 . Alternatively or additionally, balanced clocked conductors may be present in the proximal end  118 ′ of the embodiment of the implantable medical lead  200  to reduce the tendency of curvature in the proximal end  118 ′ to aid in the insertion of the proximal end  118 ′ into the lead bore  310  of the implantable medical lead extension  300 . 
       FIG. 4  shows a perspective view of an example of a proximal end  118 ,  118 ′ of the implantable medical lead device  104 , whether the lead extension  300  or the lead  200 . The lead body  105  from  FIG. 1  is shown here in a translucent manner to reveal the details within the lead body  105 . Here, the proximal portions of conductors of the lead device  104  are linear and are shown being present in balanced clocked positions within the lead device  104 . As stated above, balanced clocked positions may be achieved in relation to any two conductors that are of most similar length to each other among the conductors of the lead device  104  as measured from a given point of reference along the lead device  104  to the corresponding proximal electrical connectors of the two conductors. 
     In this example, it can be seen that from the a reference point  502  that is present at a given longitudinal position along the lead device body  105  where all eight conductors are present, each conductor has a length  504  as measured from the given reference point  502  to the corresponding electrical connector, in this case the proximal electrical connector located on the proximal end  118 ,  118 ′ of the lead device  104 . Each conductor length  504  is referenced to the conductor numbered from “ 0 -“ 7 ”. Here it can be seen that when starting from conductor “ 7 ”, which corresponds to conductor  404  having attachment  402  to electrode  120 ,  120 ′, the conductor with the most similar length to the length of conductor “ 7 ” as measured from given point  502  is conductor “ 6 ”, which corresponds to conductor  406  having attachment  406  to electrode  121 . Therefore, to provide the balanced clocked position of conductors “ 7 ” and “ 6 ”, these conductors are separated from each other by some balanced amount. 
     It can also be seen that other conductors may similarly be paired. Conductor “ 5 ” is most similar in length as measured from the given reference point  502  to conductors “ 4 ” and “ 6 ”, but since conductor “ 6 ” is paired with conductor “ 7 ” for purposes of positioning to achieve balanced clocked positions, conductor “ 5 ” may be paired with “conductor “ 4 ” and positioned to achieve balanced clocked positions. Conductor “ 3 ” is most similar in length as measured from the given reference point  502  to conductors “ 2 ” and “ 4 ”, but since conductor “ 4 ” may be paired with conductor “ 5 ” and positioned to achieve balanced clocked positions, conductor “ 3 ” may be paired with “conductor “ 2 ” and positioned to achieve balanced clocked positions. Continuing with this scheme, conductors “ 1 ” and “ 0 ” may also be paired for positioning to achieve balanced clocked positions. 
     The example shown in  FIGS. 4 and 5  includes a total of eight separate conductors and corresponding connectors. As with  FIG. 1 , it will be appreciated by one of ordinary skill in the art that the number of conductors and corresponding connectors may vary from those shown in  FIGS. 4 and 5  while still implementing balanced clocked conductor positions within the lead device  104 . 
     As discussed above, the balanced amount of angular separation may be established in multiple ways and for varying numbers of conductors that may be present within the lead device  104 . This angular separation of the example of  FIG. 4  is further shown in the lateral cross-section of the lead device  104  in  FIG. 5  which is taken through line  5 - 5  of  FIG. 4  nearby the reference point  502  where all eight conductors are present and linear in their balanced clocked positions. Note that in the example of  FIG. 5 , the lead device  104  includes the lead body  105  providing an outer layer, an inner body  602  that contains the conductors and that is surrounded by the lead body  105 , and a lumen body  604  that is surrounded by the inner body  602  and conductors and that establishes a lumen  606 . It will be appreciated by one or ordinary skill in the art that the lead devices  104  may omit one or more of these layers and still provide the balanced clocked conductor positions. 
     In one example, the angular separation  608  of  FIG. 5  that is between two conductors of most similar length when measured from the given reference point may range from 135 degrees to the maximum possible angular separation of 180 degrees regardless of the number of conductors. For instance, in one specific example of a medical lead  104  that has at least four conductors present, the angular separation  608  between the two conductors, e.g., conductors “ 7 ” and “ 6 ” that are of most similar length as measured from the given reference point, ranges anywhere from 135 degrees to 180 degrees. As shown in the example of  FIG. 5 , the angular separation  608  from center of conductor “ 7 ” to center of conductor “ 6 ” is a full 180 degrees. It can be seen that the same is true for the other three conductor pairings described above. 
     In another example, the balanced amount of angular separation may range from a quantity of angular separation  612  that is equal to at least a quantity equal to 180 degrees less a single average clocked position angular separation  610  up to the maximum possible angular separation of 180 degrees. The average single clocked position angular separation may be determined as a second quantity by dividing a full 360 degrees by the number of conductors present. For instance, in one specific example of a medical lead  104  that has at least five conductors present, the balanced amount of angular separation may range from a quantity of angular separation  612  that is equal to 180 degrees less a single average clocked position amount of angular separation  610  up to the maximum possible angular separation of 180 degrees. In the example shown in  FIG. 5  with eight conductors “ 0 ”-“ 7 ”, the balanced amount of angular separation may range from a quantity of angular separation  612  that is equal to [180 degrees less (360 degrees divided by 8=45 degrees)=135 degrees] up to the maximum possible angular separation of 180 degrees. Thus, for example, conductor “ 1 ” could swap places with conductor “ 2 ” or conductor “ 7 ” and the pairing of conductors “ 0 ” and “ 1 ” would remain in the range for being adequately balanced while the pairing of conductors “ 2 ” and “ 3 ” and the pairing of conductors “ 6 ” and “ 7 ” would also remain in the range for being adequately balanced. 
     While  FIGS. 4 and 5  show an order of conductors looking distally and going clockwise as “ 7 ,” “ 1 ,” “ 2 ,” “ 4 ,” “ 6 ,” “ 0 ,” “ 3 ,” “ 5 ,” many other orders of conductors are also applicable and allow for balanced clocked conductor positions. For instance, an alternative order of conductors looking distally and going clockwise could be “ 7 ,” “ 3 ,” “ 5 ,” “ 1 ,” “ 6 ,” “ 2 ,” “ 4 ,” “ 0 .” It will be appreciated that in both of these examples, “ 7 ” is paired with “ 6 ” to have balanced clocked positions while “ 5  is paired with “ 4 ,” “ 3 ” is paired with “ 2 ,” and “ 1 ” is paired with “ 0 .” 
     Furthermore, it will be appreciated that not all conductors present in the lead device  104  are required to have balanced clocked positions. For instance, in some cases multiple pairings of conductors having balanced clocked positions may provide adequate resistance to curving of the end even though one or more other conductors may not have balanced clocked positions. 
     Accordingly, lead devices  104  such as leads  200  and/or lead extensions  300  may be constructed by establishing one or more of these pairings of most similar in length conductors as measured from a given reference point where the two conductors of the pairing are given adequately balanced clocked positions. The adequately balanced clocked positions of one or more of these pairings then reduces the tendency of the end of the lead device  104  to curve and thereby improves the ability of the end of the lead device  104  to be inserted into a lead bore. 
     It will be appreciated that the implantable medical system  100  of  FIG. 1  that utilizes lead devices having conductors on balanced clock positions may take many different forms. For instance, the implantable medical system  100  may be a neuromodulation device capable of produce stimulation signals that provide a neurological therapy such as spinal cord stimulation, deep brain stimulation, peripheral nerve stimulation, and the like. The implantable medical system  100  may be a cardiac device capable of providing pacing signals, defibrillation signals and the like. For any of these examples and for others not explicitly mentioned, the lead device  104  may utilize the balanced clocked conductor positions like those disclosed herein. 
     While embodiments have been particularly shown and described, it will be understood by those skilled in the art that various other changes in the form and details may be made therein without departing from the spirit and scope of the invention.