Abstract:
This application discusses, among other things, an implantable medical device including a setscrew that enables lead tip visibility as an indicator of full lead insertion without requiring a grommet. In an example, the implantable medical device header is provided with a lead bore and a setscrew bore with the setscrew bore having a longitudinal axis that extends in a transverse direction to, and in communication with, the lead bore. In one example, the setscrew bore intersects with the lead bore at a location that is offset from the central longitudinal axis of the lead bore.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Reference is made to commonly-assigned and co-pending application U.S. Ser. No. 12/410,233, filed Mar. 24, 2009, entitled “Full Visibility Lead Retention;” and U.S. Ser. No. 12/410,124 filed Mar. 24, 2009, entitled “Lead Retention and Sealing Device,” all of which are herein incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present disclosure generally relates to implantable medical devices. More specifically and without limitation, this disclosure relates to headers and setscrews for implantable medical devices. 
     BACKGROUND 
     Many implantable medical devices such as pacemakers, defibrillators and neural stimulators deliver electrical therapy to tissue and sense various physiological parameters via medical leads. Such leads typically include an elongated flexible lead body with one or more electrodes disposed at a distal end of the lead. The electrodes are connected to a terminal pin on the lead&#39;s proximal end by conductors that are disposed within the lead body. 
     The lead is typically coupled to a header of the implantable medical device with a proximal portion of the lead being secured within the header to prevent the lead from dislodging. In general, the header has a connector block that includes a lead bore into which the lead&#39;s proximal portion is received. The connector block also includes a threaded setscrew bore that intersects with the lead bore. The setscrew bore receives a setscrew that engages the lead to secure it within the header. 
     The connector block is also coupled to a feedthrough pin, which passes through hermetic seals to connect with input and/or output nodes of the implantable medical device&#39;s electronic circuitry. Typically, the connector block is formed from a conductive material, such as metal, thereby permitting electrical connectivity between the lead and the electronic circuit. 
     To provide a reliable connection of the lead within the connector block, the setscrew is typically comprised of metal. Thus, the contact with the electrically active connector block causes the setscrew to be electrically active. Exposure of the setscrew to adjacent body tissue and body fluids might result in undesired electrical conduction to the adjacent tissue. Additionally, because the setscrew bore intersects with the terminal pin of the lead, ingress of fluid into the setscrew bore may result in the fluid contacting the terminal pin and this may compromise the device&#39;s delivery of electrical therapy. Consequently, a septum, typically referred to as a grommet, is disposed within the setscrew bore to cover the setscrew, thereby sealing the setscrew bore and isolating the electrically active setscrew from body fluids. In one example, the grommet is a silicone disk that has an elastic quality and has a slit that allows passage of a screw driver for tightening the setscrew and re-seals upon removal of the torque wrench to block entry of body fluids. Additionally, when the shank of the setscrew is disengaged from the threaded bore, the grommet retains the setscrew and prevents it from falling out. 
     While the use of a grommet has been satisfactory at preventing entry of fluids into the device and contact between the electrically active setscrew and surrounding tissue, it also substantially obstructs the visibility of the lead&#39;s terminal pin within the connector block. Lead tip visibility is an indicator of full lead insertion into the conductive block. The visibility enables verification that a proper and secure electrical and mechanical connection between the lead and the conductive block has been made. 
     BRIEF SUMMARY 
     Embodiments of the present disclosure provide, among other things, a setscrew that enables lead tip visibility as an indicator of full lead insertion without requiring a grommet. In one embodiment, a setscrew is provided having a metal core with an insulative coating disposed over the core to electrically isolate it from body fluids and surrounding tissue without requiring a grommet. In one embodiment, the setscrew incorporates a sealing capability by including a sealing member that is coupled to the setscrew. In another embodiment, the sealing member is disposed within the setscrew bore to engage the setscrew. The sealing capability seals the setscrew bore to prevent entry of body fluids into the implantable medical device. 
     In one embodiment, the setscrew is provided with an engagement segment on a head portion that is configured for engagement with a torque wrench. In another embodiment, a reinforcement sleeve is disposed on the setscrew head. In one example, the reinforcement sleeve is disposed on the entire head. In another example, the reinforcement sleeve is disposed on the engagement segment of the head. 
     In another embodiment, an implantable medical device header has a setscrew bore configured for engagement with a setscrew. The setscrew bore is provided with an undercut that is formed at a location proximate to the exterior opening of the setscrew bore. 
     In another embodiment, the setscrew bore has a capture mechanism that at least partially covers the exterior opening of the setscrew bore. Thus, when the setscrew is retracted from the threaded region of the bore, the capture mechanism prevents the setscrew from falling out. In some embodiments, the capture mechanism has a radial opening having a diameter that is less than the diameter of the setscrew while still allowing insertion of a torque inducing tool. 
     In another embodiment, an implantable medical device header is provided with a lead bore and a setscrew bore with the setscrew bore having a longitudinal axis that extends in a transverse direction to, and in communication with, the lead bore. In one example, the setscrew bore intersects with the lead bore at a location that is offset from the central longitudinal axis of the lead bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings are illustrative of particular embodiments of the present disclosure and therefore do not limit the scope of the disclosure. The drawings (not to scale) are intended for use in conjunction with the explanations in the following detailed description, wherein similar elements are designated by identical reference numerals. Moreover, the specific location of the various features is merely exemplary unless noted otherwise. 
         FIG. 1  is an illustration of an example implantable medical device system that has a lead extending into a heart; 
         FIG. 2A  shows a perspective view of a cut-out of the header of  FIG. 1  taken along lines  2 - 2 ; 
         FIG. 2B  shows a perspective view of an alternative embodiment of the header of  FIG. 1  taken along lines  2 - 2 ; 
         FIG. 3  is a cross-sectional view of one embodiment of setscrew  200 ; 
         FIGS. 4A-C  illustrate perspective views of the coupling between a torque wrench and a setscrew of the present disclosure; 
         FIG. 5  shows a cross sectional view of header  140  taken along lines  5 - 5  ( FIG. 1 ); 
         FIGS. 6A-B  illustrate cross sectional views of header  140  in conjunction with a prior art setscrew; 
         FIG. 7  illustrates an alternative embodiment of a setscrew of the present disclosure; 
         FIG. 8  illustrates another alternative embodiment of a setscrew of the present disclosure; 
         FIGS. 9A-B  illustrate cross-sectional views of header  140  in conjunction with setscrew  200  of  FIG. 8 ; 
         FIG. 10  illustrates a perspective view of yet another alternative embodiment of a setscrew of the present disclosure; 
         FIG. 11  illustrates a perspective view of an alternative embodiment of a coupling of lead within a header; 
         FIGS. 12A-B  illustrate alternative embodiments of a setscrew of the present disclosure; 
         FIG. 13  illustrates a perspective view of a first embodiment of a header of the present disclosure; 
         FIG. 14  illustrates a cross-sectional view of the header of  FIG. 13 , in conjunction with a setscrew of the present disclosure; 
         FIG. 15  shows a cross-sectional view of the header of  FIG. 14  in connection with a lead; 
         FIGS. 16-17  illustrate an exemplary process for making the header of  FIG. 13 ; 
         FIGS. 18A-B  illustrate perspective views of a second embodiment of a header of the present disclosure; and 
         FIG. 19  illustrates a perspective view of a third embodiment of a header of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the description provides practical illustrations for implementing exemplary embodiments of the present disclosure. 
       FIG. 1  is an illustration of an example implantable medical device system  2  including an implantable medical device (IMD) lead  135  connected to an IMD  10 . In some embodiments, IMD  10  takes the form of a cardiac pacemaker, defibrillator, neurostimulator, muscle stimulator, or gastric stimulator. As will be described in more detail below, the proximal end of lead  135  is coupled to a header  140  of IMD  10 . Lead  135  is secured in header  140  by a setscrew  200 , which will be described in more detail below. A distal end of lead  135  is coupled to an organ or any other desired tissue such as, for example, a heart  4 . IMD  10  delivers electrical stimulation to the tissue and/or detects electrical activity via electrodes  136 ,  138 . The illustration of the embodiment of  FIG. 1  showing IMD  10  coupled to a single lead  135  is merely for ease of description of the various aspects of the present disclosure and is not intended to be limiting. For example, in one or more embodiments, IMD  10  is coupled to a plurality of leads  135 . 
       FIG. 2A  is an isovolumetric sectional view of header  140  taken along lines  2 - 2  ( FIG. 1 ). Header  140  includes a connector block  150  comprised of a suitable biocompatible material that is also electrically conductive such as titanium. Connector block  150  includes a lead bore  155  into which lead  135  is received. Connector block  150  also includes a setscrew bore  165  which receives setscrew  200 . Setscrew bore  165  is oriented to be in alignment with, and intersect, lead bore  155 . In other words, the central longitudinal axis of setscrew bore  165  is oriented in a transverse direction, relative to the longitudinal axis of lead bore  155 . Therefore, when setscrew  200  is threaded into setscrew bore  165 , a distal tip  290  abuts lead  135  thereby securing it within header  140 . 
     Setscrew  200  has a tool interface  300  that has a generally cross-shaped external drive interface. An external drive interface, generally, has faces that are aligned with the thread axis and face outward. Tool interface  300  facilitates the threading of setscrew  200  into the setscrew bore  165 . 
     A sealing member  230  is coupled to setscrew  200 . The engagement of sealing member  230  between setscrew  200  and setscrew bore  165  seals the region of header  140  extending inwardly of sealing member  230  to prevent penetration of body fluids. Sealing member  230  can be any component that forms a fluid seal such as an o-ring or wiper seal. In some embodiments, the material used to form the seal is silicone. 
       FIG. 2B  illustrates an alternative embodiment of the header  140  of  FIG. 2A  incorporating sealing member  230  onto setscrew bore  165 . Thus, sealing member  230  is circumferentially disposed within setscrew bore  165 . In some embodiments, engagement of setscrew  200  compresses sealing member  230  against setscrew bore  165  or connector block  150  to form a seal. 
       FIG. 3  is a cross-sectional view of one embodiment of setscrew  200 . Setscrew  200  includes a core  205  having a head portion  220  and a threaded shank portion  210 . Shank  210  has a thread type compatible with a threaded setscrew bore  165  such, for example, as a standard 2-56 UNC-2A screw thread. In one embodiment, core  205  also includes a necked region  235 . Necked region  235  is formed between head portion  220  and shank  210  and has a narrower diameter than head  220 . In some embodiments, the sealing member  230  is coupled to necked region  235 . Core  205  includes a shoulder  280  disposed between necked region  235  and shank  210 . Shoulder  280  is dimensioned to limit the downward movement of setscrew  200  by abutting connector block  150  ( FIG. 2A ). In the illustrative embodiment of  FIG. 3 , head portion  220  and shank  210  are integrally formed to define unitary core  205 . In some embodiments, core  205  is comprised of a material having a high resiliency and strain endurance with the ability to be deformed under stress without cleaving such, for example, as a metal, organic metals or metallic polymers. In other embodiments, the material is a suitable biocompatible material and or is electrically conductive such, for example, as gold, titanium or their alloys. In other embodiments, core  205  does not significantly deform under typical loading conditions such as the forces exerted during the assembly process. 
     Setscrew  200  includes insulating coating  225  that is disposed over a portion of core  205 . In the illustrative embodiment, insulating coating  225  is disposed over head  220  and necked region  235 . Insulating coating  225  will prevent exposure of surrounding tissue or fluids to electrical current generated by IMD  10  ( FIG. 1 ) and will prevent exposure of the lead  135  to the electrical signals of the tissue outside the header. Insulating coating  225  is generally a non-conductive material that has dielectric properties. In one example, the material selected for insulating coating  225  is a biocompatible dielectric material such as polyaryletheretherketone (PEEK) thermoplastic, PARYLENE® polyxylylene polymers, or a suitable polymer material. Insulating coating  225  is coupled to core  205  by any conventional coating, molding or deposition processes. Insulating coating  225  is applied in a thickness to prevent electrical conduction via core  205  that may arise from contact with the electrically active connector block  150 . In an example where insulating coating  225  is primarily relied upon to provide electrical insulation from the surrounding medium, the thickness of insulating coating  225  is typically in the range of about 0.1 mm to about 0.8 mm (0.0039 inches to 0.0315 inches). However, the thickness of insulative coating  225  may also be determined by the thickness necessary to ensure the force from a wrench  302  ( FIG. 4A ) used to tighten and loosen the setscrew will not jeopardize the dielectric integrity of the insulator by tearing, cracking, penetrating, or otherwise weakening the insulative coating  225 . 
       FIGS. 4A-C  illustrate the coupling between torque wrench  302  and setscrew  200 . As shown in the exemplary embodiment of  FIG. 4A , tool interface  300  is configured such that it interfaces with mating segment  304  of torque wrench  302 . The apex of tool interface  300  may be configured to be a guiding surface such that it facilitates the positioning of torque wrench  302  over the setscrew  200 . As an example, the apex of tool interface  300  is formed as a dome-shape. As illustrated in  FIG. 4B  mating segment  304  fits over tool interface  300 , in direct contact with insulating coating  225 . Thus, torque applied by torque wrench  302  is transferred to both insulating coating  225  and tool interface  300 . Due to insulating coating  225  being trapped between torque wrench  302  and core  205 , the torque motion compresses insulating coating  225  against core  205 . Accordingly, insulating coating  225  is placed primarily under compressive stress, rather than shear stress. The underlying core  205  provides a high rigidity to insulating coating  225 , which is placed primarily in compression, thereby increasing the torque bearing capability of setscrew  200 . 
       FIG. 4C  illustrates a cross sectional view of the coupling of setscrew  200  to torque wrench  302 . Prongs  306  of mating segment  304  fit in between the tool interface  300  walls. Thus, the torque motion exerted by wrench  302  places insulating coating  225  in compression against core  205 . 
     With reference to  FIG. 5 , a cross sectional view of header  140  taken along lines  5 - 5  of  FIG. 1  is illustrated. Lead  135  and setscrew  200  are insertable into connector block  150  as described above. As the view illustrates, lead  135  is engaged within connector block  150  thereby providing the physical contact for electrical connectivity of lead  135  with the electrical circuit (not shown) of IMD  10 . The engagement of lead  135  with connector block  150  provides the electrical connectivity with the electrical circuit. The overall diameter arising from the implementation of setscrew  200  with a core  205  facilitates the visibility of the engagement between lead  135  and connector block  150 . Accordingly, the engagement of lead  135  with connector block  150  can be verified visually based on the protrusion of lead  135  from the connector block  150 . 
       FIGS. 6A-B  illustrate cross sectional views of assemblies of header  140  with a prior art setscrew  100 .  FIG. 6A  is a side cross sectional view (similar to lines  1 - 1  of  FIG. 1 ) showing lead  135  and a prior art setscrew  100 , such as that disclosed in U.S. Pat. No. 4,316,471 issued to Shipko et al., inserted into connector block  150 . Setscrew  100  includes a plastic head  120  that is coupled to a threaded metal shaft member  110 . Torque applied to head  120  is transferred to shaft member  110  to threadedly engage setscrew  100  within header  140 . The indirect transfer of torque from a screwdriver (not shown) to shaft member  110 , via head  120 , places head  120  under sheer stress. Due to the sheer stress loading, head  120  is formed with a large diameter to prevent tearing from the sheering stress. Thus, setscrew  100  has an overall diameter that is much larger in comparison to setscrew  200  ( FIG. 3 ). 
       FIG. 6B  illustrates the top cross sectional view (similar to lines  2 - 2  of  FIG. 1 ) of setscrew  100  inserted into header  140 . As illustrated, the large cross-sectional area of setscrew  100  obstructs visibility of connector block  150  and lead  135 . As a result of the obstructed visibility, setscrew  100  inhibits visual verification of the engagement, or lack of engagement, between lead  135  and connector block  150 . Therefore, visual determination of whether lead  135  is fully engaged, partially engaged, or fully disengaged from connector block  150  is prevented. 
     Consequently, contrasting the assembly of  FIG. 5  with the assembly in  FIG. 6B , setscrew  200  facilitates visibility of the engagement between lead  135  and connector block  150 . As described above, due to setscrew  200  being formed with core  205  having both head portion  220  and shank  210 , the overall diameter of setscrew  200  is small, relative to setscrew  100 , while maintaining the same or better torque bearing ability. Moreover, while the overall volume of setscrew  200  is much smaller compared to that of setscrew  100 , the engagement capability of setscrew  200  is still sufficient to prevent dislodgment of lead  135 . 
     Turning now to  FIG. 7 , an alternative embodiment of setscrew  200  having a reinforcement sleeve  500  is illustrated. As described above, insulating coating  225  is contemplated to come in contact with torque wrench  302  during implantation. Depending on the thickness and/or properties of insulating coating  225 , or the amount of force exerted, the contact may result in chaffing, abrasion or other physical damage that could potentially compromise the electrical insulation. Thus, reinforcement sleeve  500  is disposed over insulating coating  225  to prevent damage that may arise from improper contact between torque wrench  302  with insulating coating  225  or other mishandling of setscrew  200 . Reinforcement sleeve  500  is comprised of a resilient and high strain endurance material, for example, a metal. In certain embodiments, the material is also a suitable biocompatible material, for example, gold, titanium or their alloys. In one example, the material for reinforcement sleeve  500  is an electrically insulative material that provides electrical isolation of setscrew  200 . Reinforcement sleeve  500  is coupled to setscrew  200  through any suitable bonding method such, for example, as adhesion with an adhesive compound. In one embodiment, reinforcement sleeve  500  is bonded to head  220 , over insulating coating  225 . While not intended to be limiting, the exemplary embodiment shows reinforcement sleeve  500  enveloping a portion of head  220 . 
       FIG. 8  illustrates another embodiment of setscrew  200  of the present disclosure. In this embodiment, setscrew  200  has shank  210  detachedly coupled to head  220 . Head  220  includes an opening  605  that is disposed on distal end  600  into which a coupling segment  615  of shank  210  is received. In one example, opening  605  and coupling segment  615  are configured in an interlocking manner such as a lock and key arrangement such that coupling segment  615  is configured to fit into opening  605 . 
       FIGS. 9A-B  illustrate cross-sectional views of header  140  in conjunction with setscrew  200  of  FIG. 8 . In the illustration of  FIG. 9A , coupling segment  615  ( FIG. 8 ) is fully inserted within opening  605  ( FIG. 8 ). Head  220  is configured to be positioned at a stationary location within setscrew bore  165 . As such, vertical motion of head  220  is inhibited but rotational motion is allowed. In this embodiment, when torque is applied to setscrew  200 , head  220  rotates about the stationary location and the rotational movement causes vertical motion of shank  210  due to the engagement of the setscrew&#39;s threads with the connector block&#39;s threads. 
     As shown in  FIG. 9B , rotation of head  220  causes shank  210  to be advanced into setscrew bore  165  to abut lead  135 . Alternatively, head  220  can be rotated in the counter direction to retract shank  210  causing it to disengage lead  135 . 
       FIG. 10  illustrates a perspective view of yet another embodiment of setscrew  200 . In one example, shoulder  280  is tapered towards base  290  of setscrew  200 . The degree of taper of shoulder  280  is varied in the range between zero (0) to ninety (90) degrees. In another example, shoulder  280  has a rounded edge. 
     With particular attention now to  FIG. 11 , an alternative embodiment of the coupling of lead  135  within header  140  is illustrated. Setscrew bore  165  is formed within connector block  150  in a substantially vertical direction that is transverse to, and in communication with, the longitudinal axis of lead bore  155 . Lead bore  155  is formed in a substantially horizontal direction, relative to the orientation of setscrew bore  165 . However, unlike the embodiment of  FIG. 2 , the central longitudinal axis of setscrew bore  165  is offset from the midpoint of the longitudinal axis of lead bore  155 . Thus setscrew  200  engages lead  135  at a location other than tip  290 . For example, in the embodiment of  FIG. 11 , when setscrew  200  is threadedly coupled to the setscrew bore  165 , lead  135  is engaged by shoulder  280  of setscrew  200 . In one or more embodiments, the angle of the taper of shoulder  280  is preferably selected such that the surface in contact between setscrew  200  with lead  135  is approximately tangent to lead  135 . Thus, in some examples, the taper of shoulder  280  is selected to be about thirty (30), forty-five (45) or sixty (60) degrees. It will be appreciated that embodiments where shoulder  280  engages lead  135 , the surface area in contact between setscrew  200  and lead  135  is greater than that of  FIG. 2  where lead  135  is engaged by base  290  of shank  210  of setscrew  200 . Moreover, the offset orientation described above permits setscrew  200  and lead  135  to overlap, relative to one another, while still achieving the desired lead  135  retention functionality. 
     With reference now to  FIG. 12A , alternative embodiments of setscrews  200 A-B are illustrated. In the exemplary embodiment of setscrew  200 A, head portion  220 A of core  205  is shown having a star-shaped external drive configuration. The exemplary setscrew  200 B shows head portion  220 B having a concave-shaped external drive configuration with the concave regions having varying dimensions. It should be noted that the illustrative external drive configurations are merely exemplary and are not intended to be limiting. In alternative embodiments, head portion  220 C has an internal drive interface as illustrated in the example of  FIG. 12B . Head portion  220 C has a hollowed out region, configured with several lobed cutouts, that is integrally formed within head  220 . In comparison with an external drive interface, the internal drive interface generally has faces aligned with the thread axis and that face inward in relation to the contact surface of wrench  302 . 
       FIGS. 13-15  illustrate magnified views of an exemplary embodiment of setscrew bore  165  of header  140 . As earlier noted, IMD  10  is typically shipped with setscrew  200  already having been inserted in setscrew bore  165 . The diameter of setscrew bore  165  is typically sized to be slightly larger than the external diameter of setscrew  200 . Thus, the illustrative embodiments of header  140  prevent unintentional falling out of setscrew  200  from setscrew bore  165 . 
       FIG. 13  shows setscrew bore  165  of header  140  having an undercut  700 . Undercut  700  is formed within the setscrew bore  165 . In some embodiments, undercut  700  is located proximate within the region between an exterior opening  170  and a midpoint of setscrew bore  165 . Undercut  700  extends circumferentially at least partially around setscrew bore  165 . The structure of undercut  700  resembles a furrow or a groove. Undercut  700  functions to receive a portion of setscrew  200  thereby preventing setscrew  200  from falling out of header  140 . Additionally, a venting channel  710  that extends from the proximal opening  170  is formed within setscrew bore  165 . In some embodiments, the longitudinal dimension of venting channel  710  is sized such that head  220  will be located within a portion of venting channel  710  when setscrew  200  is disengaged from setscrew bore  165 . In one embodiment, venting channel  710  is formed using molding techniques that incorporate venting channel  710  in the formation of setscrew bore  165  within connector block  150 . In another example, venting channel  710  is formed by any suitable process that extracts the molding material, such as machining, or carving out to form the desired configuration, or depressing the wall of setscrew bore  165  at the desired location during formation of header  140 . 
       FIG. 14  illustrates a cross-sectional view of header  140  of  FIG. 13 , in conjunction with setscrew  200 . In the illustrative embodiment, undercut  700  receives a portion of setscrew  200  such, for example, as a region having the largest diameter of setscrew  200  or a protrusion of the insulating material. In the exemplary illustration, sealing member  230  has the largest diameter of setscrew  200  and thus is received by undercut  700 . Consequently, as setscrew  200  retracts from setscrew bore  165 , sealing member  230  is engaged within undercut  700  thereby preventing setscrew  200  from leaving the confines of setscrew bore  165 . In alternative implementations, undercut  700  is formed of several partial regions spaced around setscrew bore  165 . 
     Referring to  FIG. 15 , the insertion of lead  135  into header  140  of  FIG. 14  is illustrated. It should be noted that insertion of lead  135  into lead bore  155  will cause displacement of air within lead bore  155  and connector block  150 . With reference to  FIG. 2  by way of illustration, when setscrew  200  is inserted into setscrew bore  165 , sealing member  230  compresses against the walls of setscrew bore  165  thereby sealing the bore  165  and preventing flow of air. Consequently, the air in lead bore  155  causes a piston-like effect when lead  135  is inserted. In other words, the air will oppose insertion of lead  135  thereby encumbering the assembly during an implantation. Turning then to  FIG. 15 , as lead  135  is inserted into lead bore  155 , the air within lead bore  155  is permitted to freely flow between venting channel  710  and sealing member  230 . As an illustration, this free movement of air occurs through venting channel  710 . Additionally, the completed assembly of IMD  10  is typically sterilized subsequent to insertion of setscrew  200 . Venting channel  710  also facilitates the sterilization process of header  140  since the sterilization fluid is permitted to flow through easily. Venting channel  710  is located such that when setscrew  200  is fully unscrewed from the connector block  150 , fluids can freely pass through venting channel  710 . Yet, when setscrew  200  is fully screwed into the connector block  150 , fluids cannot freely pass by the sealing member  230  because the venting channel  710  does not pass through the zone between the location of the sealing member  230  when setscrew  200  is fully screwed into the connector block  150 . 
       FIGS. 16-17  illustrate an exemplary process for manufacturing setscrew bore  165  having undercut  700  within header  140 . It should be noted that the exemplary molding process for molding header  140  typically includes the use of a mold  840  having identical features to those of the desired header  140  that are inverse to those of header  140 . The manufacturing process used for the formation of header  140  is any suitable molding process such, for example, as injection molding. 
       FIG. 16  is a perspective view of a portion of exemplary mold  840  for the formation of header  140 . Mold  840  is provided with a setscrew bore-forming pin  800  for the formation of a setscrew bore  165 . Setscrew bore-forming pin  800  has a raised rib  810  for the formation of undercut  700 . The diameter of raised rib  810  is sized to be larger than the diameter of the setscrew bore-forming pin  800  such that the point of contact between raised rib  810  defines the desired undercut  700 . Pin  800  is also provided with an extended longitudinal portion  805  for the formation of venting channel  710 . At least one crest  815  is provided along the circumference of a proximal end  870  of pin  800 . 
     A molding process, such as injection molding, is performed to fill mold  840  with a molding material that is shaped into header  140 . The material is allowed to cure and subsequently, the formed header  140  is separated from mold  840 . In one example, the step of curing includes providing sufficient time for the molded material to settle and cool to a room temperature, or about twenty degrees Celsius. The material used in the molding process is a creep recovering material, or has certain deflection properties such that the material temporarily deforms when stress is exerted upon it but substantially returns to its original form when the stress is withdrawn. In one example, the material is a biocompatible material that has elastic “memory” such as TECOTHANE® thermoplastic polyurethanes. 
       FIG. 17  illustrates the step of ejection of pin  800  during the separation of mold  840  from the molded header  140 . During the ejection, raised rib  810  causes an outward expulsion of the material proximate the raised rib  810 . However, crest  815  will facilitate a controlled outward expulsion of the material at exterior opening  170  during the withdrawal motion and prevent rupture. In one example, four crests  815  are provided so that the ejection of pin  800  will cause the material to be separated into quadrants during the expulsion. Subsequent to the ejection of pin  800 , the expelled material will substantially re-form back into its pre-expulsion location because of its elastic memory and deflection properties. This re-forming creates undercut  700  at the point of contact with raised rib  810  and venting channel  710  at the location of extended longitudinal portion  805 . 
     In alternative embodiments, a flattening process is additionally utilized to further re-form molded header  140  and/or to create a smooth surface finishing along exterior opening  170  of setscrew bore  165  and the surrounding edge. In one example, the flattening process includes an annealing technique or application of heat to re-shape the material around exterior opening  170 . In another example, the flattening process includes the application of a physical force to depress the material back into setscrew bore  165 . In alternative embodiments, sealing member  230  is coupled to setscrew bore  165 . Sealing member  230  may be coupled using any known bonding technique such, for example, as a silicone adhesive. 
       FIGS. 18A-B  illustrate an alternative embodiment of header  140  having one or more protruding members  760 . In the exemplary embodiment, protruding members  760  are posts molded as part of header  140  to extend adjacent to exterior opening  170 . In an example, the protruding members  760  are molded from the same material as the header  140 . As illustrated in  FIG. 18B , upon insertion of setscrew  200 , the protruding members  760  are reflowed downward toward setscrew bore  165  using any suitable reflow process such as ultrasonic welding so as to protrude over exterior opening  170  thereby preventing setscrew  200  from falling out. 
       FIG. 19  illustrates a capture mechanism  750  extending over exterior opening  170  of setscrew bore  165 . In some embodiments, capture mechanism  750  has a radial opening  755  having a diameter that is less than the diameter of setscrew  200 . Thus, when setscrew  200  is retracted from setscrew bore  165 , capture mechanism  750  prevents setscrew  200  from falling out of setscrew bore  165 . In one embodiment, capture mechanism  750  is a rigid thin plate that is formed such that it defines a trough-shaped opening  755 . The exemplary opening  755  is sized to enable insertion of torque wrench  302  for tightening or loosening setscrew  200 . In one embodiment, channel  755  on capture mechanism  750  is aligned with a vertical axis of setscrew  200  to provide a continual line of vision to lead  135 . Capture mechanism  750  is created from a bio-compatible rigid material such, for example, as TECOTHANE® thermoplastic polyurethanes or titanium. Capture mechanism  750  is bonded to header  140  for example, at region  780 , proximate to exterior opening  170 . In one example, capture mechanism  750  is bonded through the coupling of posts  760  to correspondingly sized holes  765  by a reflow process. In another embodiment, the capture mechanism  750  is a flat washer with a hole in approximately the middle that is large enough to allow the torque wrench  302  to pass but smaller than the maximum diameter of the setscrew to prevent the setscrew from falling out of the sealing bore. In one embodiment, capture mechanism  750  is formed as part of the header  140  by constructing a correspondingly shaped mold. 
     The specific shape and size of capture mechanism  750  is predicated on keeping setscrew  200  from falling out while in its disengaged position. The shape and size of radial dimension  770  of opening  755  is controlled by various factors, for example, the assembly requirements including the size and shape of the torque wrench  302 , the shape of the tool interface  300  and/or the coupling technique. By way of example which is not intended to be limiting, alternative embodiments of capture mechanism  750  have radial dimension  770  formed to define a v-shape, or a u-shape. Additionally, the variation of radial dimension  770  facilitates the reduction of the spacing between multiple setscrew bores  165 . Thus, the variation of radial dimension  770  also enables reduction in size of header  140 . 
     In the foregoing detailed description, the present disclosure has been described in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with specific implementations that facilitate the understanding of the novel principles of the disclosure. However, it is to be understood that the principles of the present disclosure can be carried out by specifically different equipment and devices and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the disclosure as set forth in the appended claims.