Patent Publication Number: US-2021187306-A1

Title: Connector for use in overmolded header of implantable pulse generator

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Provisional Application No. 62/950,782, filed Dec. 19, 2019, which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an implantable system having an implantable lead having a connector port. More specifically, the invention relates to a connector port and components arranged within the connector port that allow for adaptability and adjustability in order to comply with various industry connector standards. 
     BACKGROUND 
     Implantable medical systems for stimulating a target area or for diagnostic purposes may include different lead configurations that require different industry standards. The systems may include an implantable lead assembly and an implantable pulse generator connected with the implantable lead assembly. The implantable lead assembly may comply with one or more of industry standards (e.g., IS-1, IS4, DF4). Further, a header of the implantable pulse generator generally includes corresponding connector ports that are configured to comply with one or more of the standards so that the implantable lead assembly may be effectively coupled with the implantable pulse generator. A proper connection between the implantable leads and the corresponding connector ports is required to allow proper functioning of the implantable system. In certain instances, a given connector port subassembly may correspond to a single standard. Components used in the connector port subassembly could allow for adaptability and adjustability to reduce the number of required connector port subassemblies. 
     SUMMARY 
     In Example 1, a connector port subassembly for a medical device includes a core subassembly; a connector bore arranged within the core subassembly including a proximal end and a distal end; one or more connector blocks configured to interference fit within the connector bore; one or more windows through the core subassembly to the one or more connector blocks; and one or more seal rings configured to interference fit within the connector bore and eliminate adulterant entry into the connector bore through the one or more windows. 
     In Example 2, the connector port subassembly of Example 1, wherein the one or more seal rings includes sidewalls, a first surface extending between the sidewalls, and a plurality of ridges arranged along the first surface and the sidewalls of the one or more seal rings configured to engage with an interior surface of the connector bore. 
     In Example 3, the connector port subassembly of Example 2, wherein a diameter of the interior surface of the connector bore is smaller than a diameter of the one or more seal rings. 
     In Example 4, the connector port subassembly of any one of Examples 2-3, wherein the one or more seal rings includes a first portion comprising a first material, and a second portion comprising a second material, and the first material is less flexible than the second material. 
     In Example 5, the connector port subassembly of Example 4, wherein the first material includes a high durometer and the second material includes a low durometer. 
     In Example 6, the connector port subassembly of Example 5, wherein the sidewalls and the first surface of the one or more seal rings comprise the first material. 
     In Example 7, the connector port subassembly of any one of Examples 1-6, wherein the connector bore includes a terminal pin cavity, and the core subassembly includes a window to the terminal pin and a projection configured to at least partially surround portions of a seal plug. 
     In Example 8, the connector port subassembly of Example 7, wherein the seal plug is captured within the connector bore producing an interference fit between the seal plug and the connector bore. 
     In Example 9, the connector port subassembly of any one of Examples 1-8, wherein the one or more seal rings includes two seal rings and the one or more connector blocks includes one connector block, and the two seal rings are arranged on either side of the connector block. 
     In Example 10, a method of manufacturing one or more connector port subassemblies includes arranging one or more connector blocks within a connector bore to interference fit within the connector bore, the connector bore being arranged within a core subassembly and having a proximal end and a distal end and one or more windows through the core subassembly configured to allow electrical interface with the one or more connector blocks; and arranging one or more seal rings within the connector bore to interference fit within the connector bore and eliminate adulterant entry into the connector bore through the one or more windows. 
     In Example 11, the method of Example 10, wherein arranging the one or more seal rings within the connector bore includes arranging a first seal ring within the connector bore, and arranging the arranging one or more connector blocks within the connector bore includes a first connector block within the connector bore, and arranging the first seal ring within the connector bore occurs prior to arranging the first connector block within the connector bore. 
     In Example 12, the method of Example 11, wherein the one or more seal rings includes two seal rings and the one or more connector blocks includes one connector block, and the two seal rings are arranged on either side of the connector block. 
     In Example 13, the method of any one of Examples 10-11, wherein arranging the one or more connector block and arranging the one or more seal rings within the connector bore includes forming a first connector port subassembly and further comprising forming a second connector port subassembly by arranging one or more connector blocks within a second connector bore to interference fit within the connector bore and arranging one or more seal rings within the second connector bore to interference fit within the second connector bore. 
     In Example 14, the method of any one of Examples 10-12, further comprising forming a header of an implantable medical device by overmolding the connector port subassembly to a housing of an implantable medical device. 
     In Example 15, the method of Example 14, wherein forming the header includes overmolding the first connector port subassembly and the second connector port subassembly to a housing of an implantable medical device, with the first connector port subassembly being arranged above the second connector port subassembly. 
     In Example 16, a connector port subassembly for a medical device includes a core subassembly; a connector bore arranged within the core subassembly including a proximal end and a distal end; one or more connector blocks configured to interference fit within the connector bore; one or more windows through the core subassembly to the one or more connector blocks; and one or more seal rings configured to interference fit within the connector bore and eliminate adulterant entry into the connector bore through the one or more windows, the one or more seal rings having sidewalls, a first surface extending between the sidewalls, and a plurality of ridges arranged along the first surface and the sidewalls of the one or more seal rings configured to engage with an interior surface of the connector bore. 
     In Example 17, the connector port subassembly of Example 16, wherein a diameter of the interior surface of the connector bore is smaller than a diameter of the one or more seal rings. 
     In Example 18, the connector port subassembly of Example 16, wherein the one or more seal rings includes a first portion comprising a first material, and a second portion comprising a second material, and the first material is less flexible than the second material. 
     In Example 19, the connector port subassembly of Example 18, wherein the first material includes a high durometer and the second material includes a low durometer. 
     In Example 20, the connector port subassembly of Example 19, wherein the sidewalls and the first surface of the one or more seal rings comprise the first material. 
     In Example 21, the connector port subassembly of Example 16, wherein the connector bore includes a terminal pin cavity, and the core subassembly includes a window to the terminal pin and a projection configured to at least partially surround portions of a seal plug. 
     In Example 22, the connector port subassembly of Example 21, wherein the seal plug is captured within the connector bore producing an interference fit between the seal plug and the connector bore. 
     In Example 23, the connector port subassembly of Example 16, wherein the one or more seal rings includes two seal rings and the one or more connector blocks includes one connector block, and the two seal rings are arranged on either side of the connector block. 
     In Example 24, an implantable medical device includes a housing; and a header attached to the housing, the header including one or more connector port subassemblies, each of the one or more connector port subassemblies having: a connector bore arranged within the core subassembly including a proximal end and a distal end, one or more connector blocks configured to interference fit within the connector bore, one or more windows through the core subassembly to the one or more connector blocks; and one or more seal rings configured to interference fit within the connector bore and eliminate adulterant entry into the connector bore through the one or more windows. 
     In Example 25, the device of Example 24, wherein the one or more connector port subassemblies include a first connector port subassembly and a second connector port subassembly, overmolded to the housing. 
     In Example 26, the device of Example 24, wherein the one or more seal rings includes a first portion comprising a first material, and a second portion comprising a second material, and the first material is less flexible than the second material. 
     In Example 27, the device of Example 26, wherein the first material includes a high durometer and the second material includes a low durometer. 
     In Example 28, the device of Example 27, wherein the sidewalls and the first surface of the one or more seal rings comprise the first material. 
     In Example 29, the device of Example 24, wherein the one or more seal rings having sidewalls, a first surface extending between the sidewalls, and a plurality of ridges arranged along the first surface and the sidewalls of the one or more seal rings configured to engage with an interior surface of the connector bore. 
     In Example 30, a method of manufacturing one or more connector port subassemblies includes arranging one or more connector blocks within a connector bore to interference fit within the connector bore, the connector bore being arranged within a core subassembly and having a proximal end and a distal end and one or more windows through the core subassembly configured to allow electrical interface with the one or more connector blocks; and arranging one or more seal rings within the connector bore to interference fit within the within the connector bore and eliminate adulterant entry into the connector bore through the one or more windows. 
     In Example 31, the method of Example 30, wherein arranging the one or more seal rings within the connector bore includes arranging a first seal ring within the connector bore, and arranging the arranging one or more connector blocks within the connector bore includes arranging a first connector block within the connector bore, and arranging the first seal ring within the connector bore occurs prior to arranging the first connector block within the connector bore. 
     In Example 32, the method of Example 31, wherein the one or more seal rings includes two seal rings and the one or more connector blocks includes one connector block, and the two seal rings are arranged on either side of the connector block. 
     In Example 33, the method of Example 30, wherein arranging the one or more connector block and arranging the one or more seal rings within the connector bore includes forming a first connector port subassembly and further comprising forming a second connector port subassembly by arranging one or more connector blocks within a second connector bore to interference fit within the connector bore and arranging one or more seal rings within the second connector bore to interference fit within the second connector bore. 
     In Example 34, the method of Example 30, further including forming a header of an implantable medical device by overmolding the connector port subassembly to a housing of an implantable medical device. 
     In Example 35, the method of Example 34, wherein forming the header includes overmolding the first connector port subassembly and the second connector port subassembly to the housing of an implantable medical device, with the first connector port subassembly being arranged above or beside the second connector port subassembly. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of an example implantable system for stimulating a target location on or within the heart, in accordance with various aspects of the present disclosure. 
         FIG. 2  is a cross-sectional view of an example connector port subassembly medical device, in accordance with various aspects of the present disclosure. 
         FIG. 3  is a cross-sectional view of another example connector port subassembly medical device, in accordance with various aspects of the present disclosure. 
         FIG. 4  is a close-up cross-sectional view of a portion of an example connector port subassembly medical device, in accordance with various aspects of the present disclosure. 
         FIG. 5  is a perspective view of an example seal ring, in accordance with various aspects of the present disclosure. 
         FIG. 6A  is close-up cross-sectional side view of an example connector port subassembly medical device and seal plug, in accordance with various aspects of the present disclosure. 
         FIG. 6B  is an perspective partially transparent view of the core subassembly and the seal plug, shown in  FIG. 6A , in accordance with various aspects of the present disclosure. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic illustration of an implantable system  100  for stimulating a target location  102  on or within the heart. As shown, the implantable system  100  includes an implantable medical device (IMD)  104  and an implantable lead assembly  106  connected to the IMD  104 . In various embodiments, the IMD  104  is an implantable pulse generator adapted to generate electrical signals to be delivered to the target location  102  for pacing and/or for sensing electrical activity at a location on or within the heart. The IMD  104  can include microprocessors to provide processing, evaluation, and to deliver electrical shocks and pulses of different energy levels and timing for defibrillation, cardioversion, and pacing to a heart in response to cardiac arrhythmia including fibrillation, tachycardia, heart failure, and bradycardia. In other instances, the implantable system  100  can also be suitable for use with implantable electrical stimulators, such as, but not limited to, neuro-stimulators, skeletal stimulators, central nervous system stimulators, or stimulators for the treatment of pain. 
     The IMD  104  may include one or more connector ports  110 ,  112 . In certain instances, the IMD (e.g., pulse generator  104 ) includes a header  108  with the connector port(s)  110 ,  112 . As shown, for example, the header  108  includes a first connector port  110  and a second connector port  112 . In addition, the implantable lead assembly  106  includes a first implantable lead  120  connected to the first connector port  110  and a second implantable lead  122  connected to the second connector port  112 . In some instances, the implantable lead assembly  106  may also include a third implantable lead (not shown) and the header  108  may include a corresponding third connector port (not shown and up to five connector ports may be used). The IMD  104  also includes a housing  116  that is connected to the header  108 . The housing  116  can include a source of power as well as electronic circuitry. The header  108  may be overmolded to the housing  116  and may be formed of a rigid polymer that is a non-conductive polymer such as, for example, an aromatic polyether-based thermoplastic polyurethane, polyether ether ketone, epoxy, or a polyethersulfone. 
     Each of the first and second implantable leads  120 ,  122  includes a flexible lead body, a plurality of conductor wires, a plurality of electrodes, and a terminal connector assembly. For example, as shown, the first implantable lead  120  includes a flexible lead body  130  having a proximal end  132 , a distal end portion  134 , and a plurality of conductor lumens  136  extending axially within the flexible lead body  130  from the proximal end  132  to the distal end portion  134 . The first implantable lead  120  also includes a plurality of conductor wires  138 , each conductor wire extending within one of the conductor lumens  136  in the flexible lead body  130 . The first implantable lead  120  further includes a plurality of electrodes  140  coupled to the distal end portion  134  of the flexible lead body  130 . Each of the electrodes  140  is electrically coupled to at least one of the plurality of conductor wires  138 . The first implantable lead  120  also includes a terminal connector assembly  142  (or terminal pin) coupled to the proximal end  132  of the flexible lead body  130 . The terminal connector assembly  142  is sized to be inserted into and received by the first connector port  110  of the header  108 . 
     Similarly, the second implantable lead  122  includes a flexible lead body  150  having a proximal end  152 , a distal end portion  154 , and a plurality of conductor lumens  156  extending axially within the flexible lead body  150  from the proximal end  152  to the distal end portion  154 . The second implantable lead  122  also includes a plurality of conductor wires  158 , each conductor wire extending within one of the conductor lumens  156  in the flexible lead body  150 . Further, the second implantable lead  122  includes a plurality of electrodes  160  coupled to the distal end portion  154  of the flexible lead body  150 . Each of the electrodes  160  is electrically coupled to at least one of the plurality of conductor wires  158 . The second implantable lead  122  also includes a terminal connector assembly  162  coupled to the proximal end  152  of the flexible lead body  150 . The terminal connector assembly  162  is sized to be inserted into and received by the second connector port  112  of the header  108 . 
     As an example of implant locations for one or more leads, the first implantable lead  120  is shown extending into a right ventricle of the heart, and the second implantable lead  122  extending through the coronary sinus and into a coronary vein disposed outside the left ventricle of the heart. The electrical signals and stimuli conveyed by the IMD  104  are carried to the electrode at the distal end of the lead by the conductors. The IMD  104  is typically implanted subcutaneously within an implantation location or pocket in the patient&#39;s chest or abdomen. 
     As shown in  FIG. 1 , the header  108  may include one or more connector port(s)  110 ,  112 . Components arranged within the connector port(s)  110 ,  112  form a subassembly that differs based on the industry standard of the lead(s)  120 ,  122  that is to be inserted into the connector port(s)  110 ,  112 . As described in further detail below, the various aspects of the present disclosure are configured to increase options in building the connector port  110 ,  112  subassemblies that are to be arranged within the header  108 . The IMD  104  may use different standards with each of the different standards requiring different numbers electrical connections and/or multiple connector port subassemblies in the same header  108 . As described in further detail below, the components and the connector port  110 ,  112  subassemblies allow for adaptability and adjustability in manufacture to lessen the number of pre-made connector port  110 ,  112  subassemblies needed to assemble headers  108  having connector port  110 ,  112  with various industry standards. 
       FIG. 2  is a cross-sectional view of an example connector port subassembly medical device, in accordance with various aspects of the present disclosure. A connector bore  202  is arranged within a core subassembly  200 , and includes a proximal end  204  and a distal end  206 . One or more connector blocks  208  are arranged within the connector bore  202 . In addition, one or more windows  210  are arranged through the core subassembly  200  to allow for electrical connection to the one of more connector blocks  208  (e.g., from circuitry arranged within a housing of an implantable medical device as described above with reference to  FIG. 1 ). One or more seal rings  212  are also arranged within the connector bore  202 . The one or more seal rings  212  are configured to interference fit within the connector bore  202  and eliminate adulterant, contaminant, or unintended materials (e.g., epoxy, overmold) from entering the connector bore  202  (e.g., lead cavity or interior lumen or portion within the one or more connector blocks  208  and seal rings  212 ) through the one or more windows  210 . 
     The core subassembly  200  may be arranged within a header  108  of an implantable medical device (as described above in detail with reference to  FIG. 1 ). The header  108  is mountable to an implantable system  100  and an electrically conductive connector block  208  located within the header  108  ( FIG. 1 ). The conductive connector block is formed from a substantially metallic material. 
     The core subassembly  200  may be overmolded to form a header, as described above with reference to  FIG. 1 . In certain instances, one or more core assemblies  200  may be overmolded to form the header. In addition and in certain instances, an adhesive or epoxy may be applied to the exterior of the one or more core assemblies  200  prior to overmolding. The one or more seal rings  212  are configured to eliminate adulterant, contaminant, or unintended materials (e.g., epoxy, overmold) contact with or entering the connector bore  202  (e.g., lead cavity) that exist due to the one or more windows  210  (e.g., electrically connect the connector blocks to components of the implantable medical device) between an exterior and an interior of the connector bore  202 . The one or more seal rings  212  block overmold material and adhesive from entering the connector bore  302  and contacting connector blocks  208 . 
     As described in further detail below, one or more connector blocks  208  and/or one or more seal rings  212  may be arranged within the connector bore  202 . The number and structure of connector blocks  208  and/or seal rings  212  may be dependent on the industry standard desired for the core subassembly  200 . As described in further detail below, the connector blocks  208  and/or seal rings  212  may be interference fit within the connector bore  202 . The interference fit of the connector blocks  208  and/or seal rings  212  maintains the location of the connector blocks  208  and/or seal rings  212  within the connector bore  202 . In this manner, the number and configuration of connector blocks  208  and/or seal rings  212  arranged within the connector bore  202 , which may be specific one or more of the industry standards (e.g., IS-1, IS4, DF4), allows for multiple permutations of multiple subassemblies  200  (having different standards) together in one header. For example, the core subassembly  200  shown in  FIG. 2  may be the IS-1 standard. In certain instances, an additional seal ring  212  is placed to surround the connector block  208  in this standard. The connector blocks  208  and/or seal rings  212  being configured as such allows for customization a connector assembly when multiple core subassemblies  200  (which may be of different standards) are arranged within a single connector assembly. In addition, the connector blocks  208  and/or seal rings  212  may have different configurations or structures and may be assembled within the connector bore  202  to comply with a desired standard. 
       FIG. 3  is a cross-sectional view of another example connector port subassembly medical device, in accordance with various aspects of the present disclosure. The subassembly medical device includes a core subassembly  300 , which may be formed from a rigid polymer that is a non-conductive polymer, and a connector bore  302 , having a proximal end  304  and a distal end  306 , arranged within the core subassembly  300 . In addition, one or more connector blocks  308  and one or more seal rings  312  are arranged within the connector bore  302 . In certain instances, the connector blocks  308  and/or the seal rings  312  are configured to interference fit within the connector bore  302 . 
     The one or more seal rings  312  and one or more connector blocks  308  may be arranged between the proximal end  304  and distal end  306  of the connector bore  302 . In certain instances and as shown, the seal rings  312  include a plurality of seal rings  312   a ,  312   b ,  312   c  and  312   d  and the one or more connector blocks  308  includes a plurality of connector blocks  308   a ,  308   b ,  308   c . The number of connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  is dependent on the industry standard desired for the core subassembly  300 . As shown, the core subassembly  300  includes three connector blocks  308   a ,  308   b ,  308   c  separated by four seal rings  312   a ,  312   b ,  312   c  and  312   d .  FIG. 3 , for example, shows a connector port subassembly that may be used for the IS-4 and DF-4 standards. 
     In certain instances, the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  are configured to interference fit within the connector bore  302 . In certain instances, the diameter of an interior surface  314  of the connector bore  302  is smaller than the diameter of the connector blocks  308   a ,  308   b ,  308   c  and/or seal rings  312   a ,  312   b ,  312   c  and  312   d . The connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  being configured to interference fit within the connector bore  302  allows for the placement tolerance required for alignment of the connector blocks  308   a ,  308   b ,  308   c  to interface with corresponding conductors on a lead that is to be inserted within the interior bore between the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d . The core subassembly  300  may be formed of a material (e.g., a thermoplastic) that is configured to yield enough to allow for arrangement of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  within the connector bore  302 . 
     In certain instances, the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  may be pressed into a desired position within the connector bore  302  at the locations needed to interface with corresponding conductors on a lead that is to be inserted into the connector bore  302 . Each of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  may be separately arranged within the connector bore  302 . In certain instances and in the configuration shown, a first seal ring  312   d  may be arranged within the connector bore  302  prior to a first connector block  308   c . In addition, a second seal ring  312   c  may be arranged within the connector bore  302  such that two seal rings  312   c ,  312   d  are arranged on either side of the connector block  308   c.    
     In certain instances, the seal rings  312   a ,  312   b ,  312   c  and  312   d  include a plurality of ridges  318  arranged along an exterior surface (contact the interior surface  314  of the connector bore  302 ) and sidewalls of the connector blocks  308   a ,  308   b ,  308   c . The plurality of ridges  318  along the sidewalls (as discussed in further detail below with reference to  FIG. 4 ) contact side portions of the connector blocks  308   a ,  308   b ,  308   c . The core subassembly  300  includes one or more windows  310   a ,  310   b ,  310   c  arranged through the core subassembly  300  to the one or more connector blocks  308 . The plurality of ridges  318  may be configured to eliminate adulterant, contaminant, or unintended materials (e.g., epoxy, overmold) from contact with or entering the connector bore  302  (e.g., lead cavity within the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d ) by way of or through the one or more windows  310   a ,  310   b ,  310   c . The plurality of ridges  318  are configured to seal out material, for example, when the core subassembly  300  is overmolded to form a header of an implantable medical device. 
     In certain instances and as shown in  FIG. 1 , the header may include multiple connectors for leads. In these instances, multiple core subassemblies  300 , that include the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d , may be overmolded together. In certain instances, the core assemblies  300  within the same header may include different configurations and numbers of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  when compared to one another. In this manner, the implantable medical device may include a header formed of the same connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and  312   d  and have connector ports for leads that comply with different industry standards. The header may include a first subassembly  300  and a second subassembly  300  (or additional subassemblies  300 ). In certain instances, forming the header includes overmolding the first connector port subassembly  300  and the second connector port subassembly  300  to a housing of an implantable medical device, with the first connector port subassembly  300  being arranged above the second connector port subassembly  300  (e.g., as shown in  FIG. 1 ) or beside the second connector port subassembly  300 . 
     In certain instances, the core subassembly  300  is configured to stretch to allow for the outer diameter of the connector bore  302  to enlarge. When multiple core subassemblies  300  (e.g., two, three, four, five) are stacked together to form a header, the connector bore  302  diameter may be altered. To prevent interference between adjacent connector bore subassemblies  300 , the connector bore  302  diameter can be reduced or enlarged in targeted areas to allow for core subassembly outer diameter to stretch above the areas with connector blocks  308  without protruding outside the greater envelope of connector bore  300  outer diameter. 
     The core subassembly  300  (or core assemblies  300 ), by way of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  and connector bore  302 , reduces the number of subassemblies required in complying with different patient device configuration needs. The connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  allow for customizable arrangements when combining subassemblies  300  into different configurations. The connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  being configured to interference fit within the connector bore  302  lessens the additive tolerance stack-up values between the components such that the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  may be placed within the connector bore  300  independently to lessen error between the components as compared to if the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  were assembled together. In addition, the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  are configured to interference fit prior to overmolding. When the overmold is placed, the core subassembly  300  is resistant to leakage as opposed to containing any windows allowing for leakage into interior or bore of the core subassembly  300 . The location of each of the connector blocks  308   a ,  308   b ,  308   c  is not dependent on the neighboring seal rings  312   a ,  312   b ,  312   c  for location. The locations of the connector blocks  308   a ,  308   b ,  308   c  in the bore may be determined by the insertion depth during the assembly process. A retaining sleeve  330  may be arranged adjacent a proximal most one of the seal rings  312   c , as shown. In other instances, the retaining sleeve  330  may be arranged adjacent a proximal most one of connector blocks  308   c . In either instance, the retaining sleeve  330  is arranged proximal to each of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c . The retaining sleeve  330  may facilitate maintaining a position of the connector blocks  308   a ,  308   b ,  308   c  and seal rings  312   a ,  312   b ,  312   c  within the connector bore  302 . 
       FIG. 4  is a close-up cross-sectional view of a portion of an example connector port subassembly medical device, in accordance with various aspects of the present disclosure. As shown in  FIG. 4 , the subassembly medical device shown includes a core subassembly  400  and a connector block  408  adjacent a seal rings  412  (which may be configured to interference fit within a connector bore as described in detail above). 
     The seal ring  412  includes a first surface  430 , a second surface  432 , and sidewalls  434 ,  436 . The second surface  432  may be configured to contact an interior lumen of a connector bore. The sidewalls  434 ,  436 , which may be angled outwardly from the second surface  432 , may be configured to contact adjacent components arranged within the connector bore. For example and as is shown, one of the sidewalls  434 ,  436  is configured to contact the connector block  408 . In certain instances, the seal ring  412  includes a plurality of ridges  418  arranged along the second surface  432  and the sidewalls  434 ,  436 . The ridges  418  on the sidewalls  434 ,  436  are configured to contact side portions of an adjacent connector block  308 . In certain instances, the ridges  418  on the sidewalls  434 ,  436  block substances (e.g., adhesive, overmolding) from entering the connector bore. The ridges  418  on the sidewalls  434 ,  436 , for example, may be configured eliminate adulterant, contaminant, or unintended materials (e.g., epoxy, overmold) from contact with or entering the connector bore (e.g., lead cavity) through the one or more windows. The plurality of ridges  418  are configured to seal out material, for example, when the core subassembly  300  is overmolded to form a header of an implantable medical device. 
     In certain instances, the seal ring  412  may include a first portion and a second portion with the first portion including a first material and the second portion including a second material. In certain instances, the first material is less flexible than the second material. More specifically, the first material may include a high durometer and the second material includes a low durometer. In certain instances, the sidewalls  434 ,  436  and the second surface  432  may be formed of the first material and the first surface  430  may be formed of the second material. 
       FIG. 5  is a perspective view of an example seal ring  520 , in accordance with various aspects of the present disclosure. As shown, the seal ring  520  includes a plurality of ridges  528  (which can also be a singular structure) on an inner surface  514  and an outer surface  518 . In certain instances, exterior ridges  528   a  are spaced closer together than interior ridges  528   b . In addition, the exterior ridges  528   a  may include less height or depth than the interior ridges  528   b.    
     In certain instances, the exterior ridges  528   a  (or structures) may be formed of a material having a first durometer and the interior ridges  528   b  (or structures) may be formed of a material having a second durometer. The second durometer may have a greater flexibility than the first durometer. The interior ridges  528   b  may have a flexibility that allows for lead insertion while the exterior ridges  528   a  may facilitate an interference fit within a connector bore as described in detail above. 
       FIG. 6A  is close-up side view of an example connector port subassembly medical device and seal plug  636 , in accordance with various aspects of the present disclosure. A terminal pin cavity  634  portion of a core subassembly  600  is shown in  FIG. 6A . The core subassembly  600  includes a window (as described in  FIG. 6B ) to the terminal pin cavity  634  that a set screw  640  is arranged within. The core subassembly  600  also includes a projection  632  configured to at least partially surround portions of a seal plug  636 . As opposed to inserting the seal plug  636  into the core subassembly  600  and sealing the seal plug  636  within the core subassembly  600  with an adhesive, the projection  632  captures the seal plug  636  within the core subassembly  600 . The projection  632  at least partially surrounds the seal plug  636 . The seal plug  636  may allow for adjustment of the set screw  640  to hold a terminal pin of a lead in place within the core subassembly  600 . Also shown is a terminal pin connector block  642 . A seal ring  644  is also arranged about the terminal pin connector block  642 , which is configured to keepout overmold material and leave a weld window  646  for wire attachment. 
       FIG. 6B  is a perspective partially transparent view of the core subassembly  600  and the seal plug  636 , shown in  FIG. 6A , in accordance with various aspects of the present disclosure. The core subassembly  600  is shown along with a connector bore  602  and windows  610   a ,  610   b ,  610   c  through the core subassembly  600  to connector blocks  608   a ,  608   b ,  608   c . As discussed in detail above, the core subassembly  600  may also include seal rings  612   a ,  612   b ,  612   c  and  612   d  are configured to interference fit within the connector bore  602  and arranged between and separating the connector blocks  608   a ,  608   b ,  608   c  from one another. The seal rings  612   a ,  612   b ,  612   c  and  612   d  may be formed of an insulative material. As also discussed in detail above, the seal rings  612   a ,  612   b ,  612   c  and  612   d  are configured to eliminate adulterant contact with or entering the connector bore  602  through the one or more windows  610   a ,  610   b ,  610   c.    
     As shown in  FIG. 6B , the projection  632  captures the seal plug  636  within the core subassembly  600 . The projection  632  at least partially surrounds the seal plug  636 . The seal plug  636  includes a window  642  through which a tool (e.g., wrench) may be inserted to adjust the set screw  640 . The seal plug  636  is configured to protect against errant wrench blade insertions and seal out material or fluids from entering the terminal pin cavity  634 . 
     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.