Abstract:
This document discusses, among other things, contrasted components for a medical device, and methods of making and using contrasted components. An example device includes a header including an opening configured to receive a set screw and a plug, and an insulative component, such as a plug or sleeve, that is insertable in the opening over the set screw. The insulative component has a visible exterior surface that is visually contrasted from a portion of the header proximate the opening. An example method includes forming from a first material a medical device header block having an opening configured to receive a plug, adding a marker to the first material or a second material, and forming from the second material a plug insertable in the opening. The marker in the second material creates or enhances a visual difference between the first material and the second material.

Description:
TECHNICAL FIELD  
       [0001]     The present subject matter relates to components for medical devices. More particularly, it pertains to contrasted components for a medical device.  
       BACKGROUND  
       [0002]     Some medical devices include leads that extend into the body. Implantable pacers and defibrillators, for example, typically include at least one lead that extends around or into the heart. A medical device such as a pacer or defibrillator typically has a header or connector block, to which one or more leads are coupled. In one configuration, a lead is inserted into a receptacle in the header, and a set screw is inserted through a second opening in the header and engaged in the header against the lead to hold the lead in place. In some instances, a lead is secured by two or three set screws. In devices that couple to multiple leads, up to six or more set screws are engaged in a header block.  
         [0003]     In some devices, a plug is inserted over a set screw. Some plugs include a slit through which a wrench can be inserted to reach a set screw beneath the seal plug. In an example, a plug is made of silicone. The silicone plug has an elastic quality that allows it to accommodate a wrench that is inserted through the slit, and then re-seal after the wrench is removed. Improved medical device components are needed.  
       SUMMARY OF THE INVENTION  
       [0004]     An example device includes an implantable housing, a pulse generator coupled to the implantable housing, and a header coupled to the implantable housing and electrically coupled to the pulse generator. The header includes a lead receptacle configured to receive a lead connector and an opening intersecting with the lead receptacle. The example device also includes a set screw insertable in the opening in the header and configured to engage a lead connector inserted in the lead receptacle, and an insulative component insertable in the opening in the header and configured to seal against the header. The insulative component includes a marker that contrasts the insulative component from the header.  
         [0005]     Another example implantable medical device includes an implantable structure including an opening configured to receive a set screw, and a plug insertable in the opening with the set screw. The plug includes a marker that contrasts the plug from the implantable structure.  
         [0006]     Another example device includes an implantable housing, a pulse generator coupled to the implantable housing, and a header coupled to the implantable housing and electrically coupled to the pulse generator. The header includes a lead receptacle configured to receive a lead connector and an opening intersecting with the lead receptacle. The device also includes a set screw insertable in the first opening in the header and configured to engage a lead connector inserted in the lead receptacle, an insulative component insertable in the first opening in the header and configured to seal against the header, and a visual indicator of the presence of the insulative component in the first opening.  
         [0007]     An example method includes adding a marker to a first insulative material or a second insulative material, the marker changing the appearance of the material. The method also includes forming from the first insulative material an implantable medical device header block having an opening, and forming from the second insulative material a component insertable in the opening in the header block. The marker in the first material or second material contrasts the insulative component from the header block. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is an illustration of an example of an implantable device that has leads extending into a heart.  
         [0009]      FIG. 2A  is a perspective view of a medical device header and leads, screws, and plugs that are insertable into the header.  
         [0010]      FIG. 2B  is a perspective view of the medical device header of  FIG. 2A  with leads, screws, and plugs assembled into the header.  
         [0011]      FIG. 3A  is a front view of a header and a plug that is contrasted from a header.  
         [0012]      FIG. 3B  is a partial side view of a screw, a plug, and a lead connector in a header block.  
         [0013]      FIG. 4A  is a perspective view of a medical device header, leads, and screws that are insertable into the header.  
         [0014]      FIG. 4B  is a perspective view of the medical device header of  FIG. 4A  with leads and screws assembled into the header.  
         [0015]      FIG. 5  is a cross-sectional view of a screw and a plug in a header block.  
         [0016]      FIG. 6  is a cross-sectional view of a screw and an insulative sleeve in a header block.  
         [0017]      FIG. 7  is a cross-sectional view of an example screw and sleeve in a header block.  
         [0018]      FIG. 8  is a cross-sectional view of an example of screw in a header block.  
         [0019]      FIG. 9  is a flow chart that illustrates a method of visually differentiating a component from surrounding structure. 
     
    
     DETAILED DESCRIPTION  
       [0020]     The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are also referred to herein as “examples.” The drawings and following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.  
         [0000]     Overview  
         [0021]     An insulative component, such as plug, is visually differentiated from an implantable structure, such as a medical device header, into which the component is inserted. An example medical device including a header block and contrasting plugs is shown in  FIG. 1 . In an example, the header block includes polyurethane or epoxy and the plug includes silicone and a marker to contrast the plug from the header block. In one example, the entire plug is contrasted from the header. In another example, only a visible external surface of the plug is contrasted from the header.  
         [0022]     In an example, contrasting a component such as a plug from the surrounding structure facilitates location of the component in the device during a medical procedure, such as an implant or explant. In another example, contrasting a component from surrounding structure facilitates verification that a component is present in an opening in the header block. In a device that contains multiple set screws and multiple plugs, for example, it can be helpful to visually verify that the plugs have been assembled into the device, and the contrasting components allow the location of the plugs and/or screws to be easily found.  
         [0023]      FIGS. 2A-2B  show an example configuration of a header, screws insertable in the header, and contrasting plugs insertable over the screws.  FIG. 3A  shows a front view of a header and plugs that are contrasted from a header.  FIG. 3B  is a side view that shows a plug that is visible through a header block.  FIGS. 4A-4B  show an example of a device in which a screw and an insulative sleeve are assembled into a header block, and the screw and/or the sleeve is contrasted from the header block.  FIGS. 5-8  show partial cross sections of example connectors and related structure.  FIG. 9  is a flow chart that illustrates a method of visually differentiating a component from surrounding structure in a medical device.  
         [0000]     Example Techniques for Differentiating Components  
         [0024]     In an example, insulative components such as the plugs shown in  FIGS. 2A-2B  are made from an insulative material such as silicone, and a structure such as the header shown in  FIGS. 2A-2B  is made from a material that has an appearance similar to silicone, such as polyurethane or epoxy. Polyurethane and epoxy are typically similar in appearance to silicone: Silicone, polyurethane, and epoxy tend to be translucent and mostly colorless. This similarity can make it difficult to visually identify a silicone plug assembled into a polyurethane or epoxy header. For example, in an operating environment, it can be difficult to identify the location of plugs in a device if the silicone material from which the seal plugs are made is similar in color to the header block.  
         [0025]     To visually differentiate an insulative component from the surrounding structure, an insulative material is doped, modified, or otherwise processed to modify the appearance of the material. In an example, a marker is added to the insulative component. In an example, the marker is a color agent, such as a pigment, dye, resin, or polymer. In an example, the marker is a pigment such as titanium dioxide (TiO 2 ). In an example, the color agent is an opaque pigment or dye. In another example, the color agent is a translucent or transparent pigment or dye. In an example, the color agent changes the color, opacity, and/or reflectivity of the insulative component.  
         [0026]     In another example, the plugs are made from a fluorescent material. In an example, a marker is added to silicone to make the silicone fluorescent.  
         [0027]     In another example, the plugs are made from a material that is excitable to ultra-violet (UV) light. In an example, a UV-excitable marker is added to silicone.  
         [0028]     In another example, the marked is added by oxidizing the insulative component material to change the appearance of the material. In an example, a silicone plug material is oxidized.  
         [0029]     In another example, aeration and/or oxygenation are used to change the density and color of the material.  
         [0030]     In another example, a coating is applied to at least a portion of the insulative component. In an example, a coating is applied to a portion of an outwardly-facing surface of a silicone plug.  
         [0031]     In an example, multiple pigments or other markers are used to differentiate among connectors on a header.  
         [0032]     In another example, a marker is added to a header to visually differentiate the header from clear, translucent, or colored plugs or screws.  
         [0033]     In another example, a clear or translucent plug is assembled over a colored screw or washer. In another example, a bonding agent includes a marker and is bonded to a plug or screw. In an example, the bonding agent is a bead of pigmented adhesive disposed around the perimeter of a clear, translucent, or colored plug.  
         [0000]     Example Devices and Systems  
         [0034]     Referring now to  FIG. 1 , an example implantable medical device  100  includes a header  105  and contrasting insulative components  120 ,  125 . In the example shown in  FIG. 1 , insulative components  120 ,  125  are plugs. Lead assemblies  110 ,  115  are coupled to the header  105 . In the example shown in  FIG. 1 , lead assembly  110  extends into the right side of the heart and lead assembly  115  extends into the left side of the heart  101 . In an alternative example, the lead assemblies extend on or around the outside of the heart, or on or around other organs or nerve centers where stimulation or sensing is needed.  
         [0035]     Each lead assembly  110 ,  115  includes one or more leads that is coupled to the header  105  with connector, such as a screw, that is inserted through an opening in the header. Connection systems are shown in more detail in  FIGS. 2A-2B ,  4 A- 4 B,  5 , and  6 . In the example shown in  FIG. 1 , plugs  120 ,  125  are inserted into the openings in the header block over screws. In an example, the plugs  120 ,  125  create a seal against the header.  
         [0036]     The plugs  120 ,  125 , shown in  FIG. 1  are contrasted from the header through one of the techniques described above. In an example, the contrast between the plugs and the header facilitates location of the plugs by a surgeon during implant or explant of the device  100 .  
         [0037]     In an example, titanium dioxide powder, which is typically white, is used as a pigment for silicone. The titanium dioxide powder is mixed with silicone, and the silicon/titanium dioxide powder is molded into a seal plug. The molded seal plug is white. The white seal plug contrasts against a typically transparent or translucent polyurethane header. It is understood that other pigments or other marking techniques can be used.  
         [0038]     Referring now to  FIG. 2A , an example medical device  200  includes a header  205  and contrasting plugs  245 ,  246 ,  247 ,  248 ,  249 ,  250 ,  251 ,  252 . The header  205  includes a header block and internal electrical connections and electrical circuitry. Header  205  has an end surface  206 , front face  207 , a top  208 , and a back face  209 . The end surface  206  includes receptacles  220 ,  221 ,  222 ,  223 ,  224  into which respective leads  210 ,  211 ,  212 ,  213 ,  214  can be inserted. The leads  210 ,  211 ,  212 ,  213 ,  214  include lead connectors, such as pins  215 ,  216 ,  217 ,  218 ,  219 . When the leads are assembled into the header  205 , pins  215 ,  216 ,  217 ,  218 ,  219  on the leads  210 ,  211 ,  212 ,  213 ,  214  contact the electrical connections on the inside of the header. In an example, pins  215  and  216  connect to a defibrillation circuit, pins  217  and  218  connect to a sensing circuit, and pin  219  connects to a pacing circuit. In an example, two or more of the leads are combined into a lead assembly.  
         [0039]     In an example, a lead is coupled to the header with one or more connectors, such as a set screw. In the example shown in  FIG. 2A , lead  211  is insertable in opening  221  and connectable to header  205  with screw  238  that is insertable into opening  228  in the top  208  of the header. Screw  238  is engageable on threaded portions of the header. Screw  238  engages the pin  216  on the lead  211 . Plug  248  is insertable in the opening  228  over the screw  238 . In an example, the plug  248  covers the respective screw  238  and prevents body fluid from traversing the opening  228  and contacting the screws. In an example, the plug prevents electrical conduction from the screw  238  through the opening  228 .  
         [0040]     The other leads shown in  FIG. 2A  can also be coupled to the header with screws. Lead  210  is connectable to header  205  with screw  239  that are insertable into opening  229  in the top  208  of the header. Screw  239  engages the pin  215  on the lead  210 . Plug  249  is insertable in the opening  229  over the screw  239 . Lead  214  is connectable to header  205  with screws  236 ,  237  that are insertable into openings  226 ,  227  in the front face  207  of the header. Screw  236  engages the pin  219  on the lead  214  and screw  239  engages a ring portion  259  of the lead. Plugs  246 ,  247  are insertable in the openings  226 ,  227  over the screws  236 ,  237 . Leads  213 ,  212  are connectable to header  205  with respective screws  235 ,  242  that are insertable into respective openings  225 ,  232  in the respective front and back faces  207 ,  209  of the header. Plugs  245 ,  252  are insertable in the respective openings  225 ,  232  in the header to cover respective screws. Plugs  250 ,  251  are insertable in openings  230 ,  231  over screws  240 ,  241 .  
         [0041]     In an example, the plugs  245 ,  246 ,  247 ,  248 ,  249 ,  250 ,  251 ,  252  include a marker, such as a color agent, oxidized surface or volume, fluorescent or UV-excitable agent, or a coating.  
         [0042]     Referring now to  FIG. 2B , the medical device of  FIG. 2A  is shown with leads, screws, and plugs assembled into the header. The leads  210 ,  211 ,  212 ,  213 ,  214  are inserted into openings  220 ,  221 ,  222 ,  223 ,  224  in the end of the header. The plugs  245 ,  246 ,  247 ,  248 ,  249 ,  250 ,  251 ,  252  are inserted in the respective openings  225 ,  226 ,  227 ,  228 ,  229 ,  230 ,  231  over the respective connectors  235 ,  236 ,  237 ,  238 ,  239 ,  240 ,  241 ,  242 .  
         [0043]     In an example, one or more of the plugs includes a slit through which a wrench can be inserted. Plug  245 , for example, includes a slit  260  ( FIG. 2A ). In an example, the plug  245  is formed from an elastic material, such as silicone, which can be displaced to accommodate a wrench through the slit. When the wrench is removed, the elastic material returns to its original shape, and the slit closes.  
         [0044]     In an example, an exposed outer surface of a component is contrasted from local portions of header block. In  FIG. 3A , for example, the outer surfaces  315 ,  316 ,  317  of plugs  310 ,  311 ,  312  are contrasted from the appearance of header block  305 .  FIGS. 2A and 2B  also show plugs that have an outer surface that is visually differentiated from the header.  
         [0045]     In another example, a header is translucent or transparent, and a side portion of a plug or other component is contrasted from the header material, such that the component is visually detectable through the block. In the side view shown in  FIG. 3B , for example, seal plug  320  is visible through header block  325 . In the example shown in  FIG. 3B , a screw  330  and lead  335 , and electrical terminal  340  are also visible through the header block. In an example, the visibility of the plug  320  through the header block facilitates confirmation that plugs and/or screws have been assembled into the block.  
         [0046]     Referring now to  FIGS. 4A and 4B , another example of a medical device  400  includes a header  405 , a screw  430  and sleeve  440 . The sleeve  440  and/or screw are contrasted from the header. Both the screw  430  and the sleeve  440  are insertable an opening  425  in the header  405 . The screw is shown inserted into the sleeve in  FIG. 4A . The structure of an example screw and sleeve is shown in cross-section in  FIG. 6 .  
         [0047]     Returning to  FIG. 4A , the header  405  includes a header block  406  and internal circuitry. The screw  430  includes a threaded shaft  435  and an insulative cap  437  that is coupled to the screw. The cap  437  also includes a driver interface  450  that is configured to receive a driver, such as a wrench. The sleeve  440  includes an orifice  452  through which a wrench can be inserted to turn the screw. The screw  430  is insertable into the sleeve  440 . Both the sleeve  440  and screw  430  are insertable into an opening  425  in the header block  406 . The threaded shaft  435  engages internal threads in the header. The example in  FIG. 4A  also includes a second screw  431  that includes a threaded shaft  436  and an insulative cap  438  connected to the threaded shaft. Screw  431  is insertable into sleeve  441 . Screw  431  and sleeve  441  are insertable in opening  426  in the header block  406 .  
         [0048]     Referring again to  FIG. 4A , leads  410 ,  411  are insertable in openings  420 ,  421  in the header  405 . Pins  415 ,  416  on the leads are shaped and sized to contact electrical connections in the header  405 . The threaded shafts  435 ,  436  are engagable against the pins  415 ,  416  to secure the pins and leads  410 ,  411  in the header  405 .  FIG. 4B  shows leads  410 ,  411  and screws  430 ,  431  assembled into the header  405 .  
         [0049]      FIG. 5  is a cross-sectional view of an example system that includes a plug  505  and screw  515  in a header  510 . Header  510  includes header block  520  and threaded screw terminal  525 . When the screw is turned, it descends into lead receptacle  530  and presses against lead connector  535 . The plug  505  includes a slit  540 , through which a wrench can be inserted. In an example, the plug is sized to create a press fit in the opening  545  in the header block  520 . The plug  505  is contrasted from the header block portion of the header  510 . In an example, the plug is formed from silicone that includes a marker that changes the appearance of the silicone.  
         [0050]      FIG. 6  shows another example system that includes a sleeve  605  and a screw  610  in a header  615 . Header includes header block  616  and connector terminal  630 . Screw  610  includes an insulative cap  620  coupled to a threaded shaft  625 . In an example, the cap  620  is overmolded onto the shaft  625 . In an example, the cap  620  is overmolded onto the shaft  625  in an insert-molding process. The threaded shaft  625  screws into the connector terminal  630 . When the threaded shaft  625  is turned, it descends into lead receptacle  635  and contacts a lead connector (not shown). In an example, the insulative cap  620  is over-molded on the threaded shaft  625  in an insert-molding process. The insulative cap  620  includes one or more ribs  640  that press against the sleeve  605 . In an example, the sleeve  605  is formed from a compressible material, such as silicone. In an example, the sleeve  605  includes a marker that contrasts the sleeve from the header block portion of the header  615 . In another example, the insulative cap  620  includes a marker that contrasts the cap  620  from the header block portion of the header  615 . In an example, the cap is formed from a colored polymer. In an example, both the sleeve and the insulative cap include a marker that contrasts the sleeve and the insulative cap from the header block  616 . In an example, the insulative cap  620  includes a marker that is different from the marker included in the sleeve  605 .  
         [0051]      FIG. 7  shows a cross-sectional view of another example screw  700 . A cap  705  is connected to a threaded shaft  710  and insertable in a sleeve  730 . The cap  705  is formed from a non-conductive material, such as a non-conductive polymer. In an example, the cap  705  is over-molded on the threaded shaft  710 . In an example, the threaded shaft includes a structure  715  that facilitates transfer of torque from the cap to the screw. In an example, the structure  715  is cross-shaped. The cap also includes a driver interface  720 . The cap is insertable in the sleeve  730 . In an example, the sleeve  730  includes a rib  735  that presses against the cap  705  to make a seal. Alternatively the sleeve is configured to make a press fit between the cap  705  and an internal surface of an opening in a header block. In an example, the sleeve  730  includes a marker that contrasts the sleeve from a header or other structure. In another example, the cap includes a marker that contrasts the cap from a header or other structure. In another example, both the sleeve and the cap include markers that contrast the sleeve and cap from a header or other structure.  
         [0052]      FIG. 8  shows another example screw  800 , in which one or more compressible ribs  840  are coupled to a cap  805 . Cap  805  is connected to a threaded shaft  810 . The cap  805  is formed from a non-conductive material, such as a non-conductive polymer. In an example, the cap  805  is over-molded on the threaded shaft  810 . In an example, the threaded shaft includes a structure  815  that facilitates transfer of torque from the cap to the screw. In an example, the structure  815  is cross-shaped. The cap also includes a driver interface  820 . Compressible ribs  840  are coupled to the cap. In an example, the compressible ribs are O-rings. Compressible ribs  840  press against an inner surface  845  of an opening  855  in a header  850  to form a seal. The cap  805  includes a marker to contrast the cap  805  from the header  850 .  
         [0053]      FIG. 9  is a flow chart that illustrates a method of differentiating a component from surrounding structure. At  905 , a marker is added to a first insulative material or a second insulative material. The marker changes the appearance of the material to which it is added. At  910 , an implantable medical device header block is formed from the first material. The implantable medical device header block includes an opening, into which a screw and seal plug can be inserted, for example. At  915 , a component, such as a seal plug or sleeve, is formed from the second insulative material. In an example forming a component from the second material includes insert molding a cap onto a threaded shaft. The marker in the first material or second material contrasts the insulative component from the header block. In an example, the first material is polyurethane or epoxy, and the second material is silicone. In an example, adding a marker includes oxidizing at least a portion of the first or second insulative material, such as oxidizing silicone, for example. In an example, adding a marker includes adding a color agent. In an example, adding a marker changes the opacity, reflectivity and/or color of the first or second material. In an example, a marker is added to both the first material and the second material.  
         [0054]     It is to be understood that the above description is intended to be illustrative, and not restrictive. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.