Patent Publication Number: US-7711428-B2

Title: Hermetic lead connector assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of priority to U.S. Provisional Application No. 60/885,433, entitled “INTERNAL HERMETIC LEAD CONNECTOR FOR IMPLANTABLE DEVICE” filed on Jan. 18, 2007, the disclosure of which is incorporated herein by reference. 

   FIELD 
   The present disclosure relates to hermetic lead connector assemblies for an implantable device and particularly to method of manufacturing an active medical implantable device having a lead connector assembly disposed within the hermetic housing of the device. 
   BACKGROUND 
   Implantable active medical devices, such as cardiac rhythm management devices (pacemakers and defibrillators) and a variety of implantable muscle/nerve stimulators generally include a battery and battery-powered electronic pulse generator contained within a hermetically sealed housing or case and attached to a lead connector housing or lead connector block. The lead connector block is often affixed to the hermetically sealed housing with brackets, metal solder, and/or a medical grade adhesive. 
   The electronics within the hermetically sealed housing are conductively coupled to the lead connector block with an electrical feedthrough assembly. Electrical feedthroughs serve the purpose of providing a conductive path extending between the interior of a hermetically sealed container and a point outside the hermetically sealed housing. The conductive path through the feedthrough usually includes a conductor pin or terminal that is electrically insulated from the hermetically sealed housing. Many such feedthroughs are known in the art that provide the conductive path and seal the electrical container from its ambient environment. Such feedthroughs typically include a ferrule, and an insulative material such as a hermetic glass or ceramic seal that positions and insulates the pin within the ferrule. Sometimes it is desired that the electrical device include a capacitor within the ferrule and around the terminal, thus shunting any electromagnetic interference (EMI) at high frequencies at the entrance to the electrical device to which the feedthrough device is attached. Typically, the capacitor electrically contacts the pin lead and the ferrule. While this arrangement has proven to be highly reliable, it involves a variety of expensive manufacturing processes and parts that necessarily increase the cost of the resulting product. 
   Ongoing efforts by the industry to reduce the size of the implantable device are desired. Early implantable pacemakers back in the 1960&#39;s were about the size of a hockey puck. With advances in microelectronics and integrated circuitry, significantly more features and capabilities have been embodied in implantable active medical devices capable of sizes as small as about 10 cc. Nonetheless, efforts to further reduce the size of implantable active medical devices continue in the industry. 
   BRIEF SUMMARY 
   The present disclosure relates to hermetic lead connector assemblies for an implantable device and particularly an active medical implantable device having a lead connector assembly disposed within the hermetic housing of the device. 
   In a first embodiment, a hermetic lead connector assembly includes a hermetic lead connector having an open end, an outer surface and an inner surface defining a lead aperture and a rigid sleeve is disposed about the hermetic lead connector outer surface. The lead connector has one or more electrically conducting contact rings spaced apart by electrically insulating rings. The lead connector provides a hermetic seal between the lead connector outer surface and the lead connector inner surface. The rigid sleeve has an aperture that exposes a portion of the one or more electrically conducting contact rings. 
   In another embodiment, a hermetic lead connector assembly includes a hermetic lead connector having an open end, an outer surface and an inner surface defining a lead aperture. The lead connector has a plurality of ring subassemblies fixed in axial alignment, and each ring subassembly includes an insulating ring fixed between an electrically conducting contact ring and an electrically conducting spacer ring. The lead connector provides a hermetic seal between the lead connector outer surface and the lead connector inner surface. A rigid sleeve is disposed about the hermetic lead connector outer surface. The rigid sleeve has an aperture that exposes a portion of the one or more electrically conducting contact rings. 
   In a further embodiment, an implantable active medical device includes a hermetically sealed housing defining a sealed housing interior, a power source and electronics are in electrical communication and disposed within the sealed housing interior. A hermetic lead connector projects into the sealed housing interior and has an open end, an outer surface and an inner surface defining a lead aperture. The lead connector has one or more electrically conducting contact rings spaced apart by electrically insulating rings. The lead connector provides a hermetic seal between the lead connector outer surface and the lead connector inner surface. A rigid sleeve is disposed about the hermetic lead connector outer surface. The rigid sleeve has an aperture that exposes a portion of the one or more electrically conducting contact rings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
       FIG. 1  is a schematic diagram of an active medical device implanted within a human body; 
       FIG. 2  is a schematic exploded view of an implantable active medical device; 
       FIG. 3  is a schematic cross-sectional view of an lead body shown in  FIG. 2  taken along line  3 - 3 ; 
       FIG. 4A  is a schematic diagram cross-sectional view of an illustrative active medical device; 
       FIG. 4B  is a schematic diagram cross-sectional view of another illustrative active medical device; 
       FIG. 5  is a schematic cross-sectional view of an illustrative lead connector assembly; 
       FIG. 6  is an exploded perspective view of the illustrative lead connector assembly shown in  FIG. 5 ; 
       FIG. 7  is an exploded perspective cut-away view of the illustrative subassembly shown in  FIG. 6 ; 
       FIG. 8  is a perspective cut-away view of the illustrative subassembly shown in  FIG. 6 ; 
       FIG. 9  is a perspective cut-away view of the illustrative subassembly shown in  FIG. 6 ; 
       FIG. 10  is a perspective view of the illustrative subassembly shown in  FIG. 6 ; 
       FIG. 11  is a perspective view of the illustrative lead connector assembly shown in  FIG. 5 ; and 
       FIG. 12  is a perspective view of another illustrative lead connector assembly shown in  FIG. 5 . 
   

   The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. 
   DETAILED DESCRIPTION 
   In the following description, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense. 
   All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure. 
   Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. 
   The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range. 
   As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
   The term “active implantable medical device” or “implantable signal generator” are used interchangeably and includes, for example, a cardiac pacemaker, an implantable defibrillator, a congestive heart failure device, a hearing implant, a cochlear implant, a neurostimulator, a drug pump, a ventricular assist device, an insulin pump, a spinal cord stimulator, an implantable sensing system, a deep brain stimulator, an artificial heart, an incontinence device, a vagus nerve stimulator, a bone growth stimulator, a gastric pacemaker, and the like. 
   The term “hermetic seal”, “hermetically sealed” are used interchangeably and refer to an airtight seal. This term is often used to describe electronic parts that are designed and intended to secure against the entry of microorganisms, water, oxygen, and the like, and to maintain the safety and quality of their contents. 
   The present disclosure relates to a hermetic lead connector for an implantable device and particularly to an active medical implantable device having a lead connector disposed within the hermetic housing of the device. The internal hermetic lead connector allows electronics within the hermetic housing of the device to be directly coupled to the lead connector, thus a separate attached conventional feedthrough connector block is not needed. Elimination of the separate feedthrough connector block reduces the number of parts and connections needed to assemble the active medical implantable device and can reduce the overall size of the active medical device. While the present invention is not so limited, an appreciation of various aspects of the invention will be gained through a discussion of the examples provided below. 
     FIG. 1  is a schematic diagram of an active medical device  20  implanted within a human body or patient  28 . The implanted active medical device  20  is illustrated as a neurostimulator, however, the implanted active medical device  20  can be any “active implantable medical device” or “implantable signal generator” as described above and can be placed in any location within a body cavity or tissue within the body, or on the surface of a patient&#39;s skin, as desired. 
   The active medical device  20  is coupled to a lead extension  22  having a proximal end coupled to the active medical device  20 , and a lead  24  having a proximal end coupled to a distal end  32  of the lead extension  22  and a distal end of the lead  24  coupled to one or more electrodes  26 . In other embodiments, the lead  24  proximal end is coupled to the active medical device  20 , without a need for a lead extension  22 . The active medical device  20  can be implanted in any useful region of the body such as in the abdomen of a patient  28 , and the lead  24  is shown placed somewhere along the spinal cord  30 . In many embodiments, the active medical device  20  has one or two leads each having four to eight electrodes. Such a system may also include a physician programmer and a patient programmer (not shown). The active medical device  20  can be considered to be an implantable signal generator of the type available from Medtronic, Inc. and capable of generating multiple signals occurring either simultaneously or one signal shifting in time with respect to the other, and having independently varying amplitudes and signal widths. The active medical device  20  contains a power source and the electronics for sending precise, electrical signals to the patent to provide the desired treatment therapy. While the active medical device  20 , in many embodiments, provides electrical stimulation by way of signals, other forms of stimulation may be used as continuous electrical stimulation. 
   In many embodiments, the lead  24  is a wire having insulation thereon and includes one or more insulated electrical conductors each coupled at their proximal end to a connector and to contacts/electrodes  26  at its distal end. Some leads are designed to be inserted into a patient percutaneously (e.g. the Model 3487A Pisces—Quad® lead available from Medtronic, Inc.), and some are designed to be surgically implanted (e.g. Model 3998 Specify® lead, also available form Medtronic, Inc.). In some embodiments, the lead  24  may contain a paddle at its distant end for housing electrodes  26 . In many embodiments, electrodes  26  may include one or more ring contacts at the distal end of lead  24 . 
     FIG. 2  is a schematic exploded view of the implantable active medical device described above and  FIG. 3  is a schematic cross-sectional view of the lead extension body  100  shown in  FIG. 2  taken along line  3 - 3 . The implantable active medical device  102  can be coupled to a lead extension  100  configured to be coupled between an implantable active medical device  102  and the lead  104 . The proximal portion of lead extension  100  includes a lead connector  107  configured to be received or plugged into housing lead connector  105  of the implantable active medical device  102  through a hermetically sealed housing  109  of the implantable active medical device  102 . The distal end of extension  100  includes a connector  110  including internal contacts  111  and is configured to receive the proximal end of lead  104  having contacts  112  thereon. The distal end of lead  104  includes distal electrodes  114  that are in electrical connection with corresponding contacts  112 . 
   In some embodiments, lead extension  100  can differ from lead  104  in that each conductor  106  in the lead body is helically wound or coiled in its own lumen  108  and not co-radially wound with the rest of the conductors as can be the case in lead  104 . 
     FIG. 4A  is a schematic diagram cross-section view of an illustrative active medical device  102 . The active medical device  102  includes a hermetically sealed housing  109  defining a sealed housing interior. A power source  21  and electronics  23  are in electrical communication and are disposed within the sealed housing  109  interior. A lead connector  105  projects into the sealed housing  109  interior and has an inner surface  167  defining a lead aperture  165 . 
     FIG. 4B  is a schematic diagram cross-section view of an illustrative active medical device  102 . The active medical device  102  includes a hermetically sealed housing  109  defining a sealed housing interior. A power source  21  and electronics  23  are in electrical communication and are disposed within the sealed housing  109  interior. A lead connector  105  projects into and through the sealed housing  109  interior and has an inner surface  167  defining an open lumen lead aperture  165 . 
   The hermetically sealed housing  109  includes a first surface  27  and an opposing second surface  25 . The lead connector  105  projects through the hermetically sealed housing  109  from the first surface  27  to the opposing second surface  25 . Thus the lead connector  105  forms an open-ended lumen through the hermetically sealed housing  109  where the lead connector  105  has a first open end  166  at the first surface  27  and a second open end  168  at the second surface  25 . 
   The lead connector  105  includes one or more electrically conducting contact rings  130  spaced apart by one or more electrically insulating rings  140 . The one or more electrically conducting contact rings  130  are in electrical communication with the electronics  23  and the lead connector  105  provides a hermetic seal between the sealed housing  109  interior and the lead aperture  165 . The electronics  23  generally control the active medical device  102 . The power source  21  can be any useful battery or power source such as an inductive coil. In some embodiments, the electronics  23  includes memory. The memory can be any magnetic, electronic, or optical media, such as random access memory (RAM), read-only memory (ROM), electronically-erasable programmable ROM, flash memory, or the like. 
   The one or more electrically conducting contact rings  130  can be formed of any useful electrically conductive material. In many embodiments, the one or more electrically conducting contact rings  130  are formed of a metallic material such as, for example, titanium, stainless steel, MP35N, niobium, tantalum, platinum, and alloys or combinations thereof In some embodiments, the one or more electrically conducting contact rings  130  are formed of a metallic material such as, for example, titanium. 
   The electrically insulating rings  140  can be formed of any useful electrically insulating material. In many embodiments, the one or more electrically insulating rings  140  are formed of a single crystal sapphire, a polycrystalline or single crystal ceramic, or glass. In some embodiments, the one or more electrically insulating rings  140  are formed of a single crystal sapphire. 
   In some embodiments, a filtering capacitor is disposed between the electrically conducting contact rings  130  and the electronics  23 . The filtering capacitor can effectively filter out undesirable electromagnetic interference (EMI) from the active medical device  102 . 
   The implantable active medical device described herein can eliminate the need for a conventional separate feedthrough block that electrically connects a conventional lead connector block with the hermetically sealed electronics of the implantable active medical device. By placing the lead connector within the hermetically sealed active medical device housing, a direct electrical connection between the lead connector and the electronics can be made. In addition, the elimination of a feedthrough can reduce the size and volume of the implantable active medical device and can also reduce the number of parts and connections needed to assemble the implantable active medical device. 
     FIG. 5  is a schematic cross-sectional view of an illustrative lead connector assembly  101 .  FIG. 6  is an exploded perspective view of the illustrative lead connector assembly  101  shown in  FIG. 5 . The illustrated lead connector  105  is an elongate member extending between a lead aperture  165  open end  166  and a lead connector end cap  145 , and having an inner surface  167  defining a lead aperture  165 . The lead aperture  165  is configured to accept a lead or lead extension, as described above, and electrically couple one or more lead contacts with one or more connector contacts  130  that form the elongate body of the lead connector  105  assembly, that in many embodiments is generally cylindrical. 
   In many embodiments, the lead aperture  165  is a cylindrical lumen of generally circular cross-sectional area formed by an inner surface of the electrically conducting rings  130  and electrically insulating rings  140  welded or brazed together in axial alignment. The lead connector  105  defines a lead connector outer surface  170  and at least a portion of the lead connector outer surface  170  is disposed within the sealed housing  109  interior. In many embodiments, at least a majority of the lead connector outer surface  170  is disposed within the sealed housing  109  interior. In many embodiments, substantially the entire lead connector outer surface  170  is disposed within the sealed housing  109  interior. In some embodiments, the entire lead connector outer surface  170  is disposed within the sealed housing  109  interior. 
   In the illustrated embodiment, the lead connector  105  is formed of one or more electrically conducting contact rings  130  spaced apart by one or more electrically insulating rings  140 . The one or more electrically conducting contact rings  130  are in electrical communication with the electronics (described above), and the lead connector  105  body provides a hermetic seal between the sealed housing interior/lead connector outer surface  170  and the lead aperture  165 . The one or more electrically conducting contact rings  130  and one or more electrically insulating rings  140  are assembled in axial alignment to form the lead connector  105 . 
   The one or more electrically conducting contact rings  130  can include one or more additional contact elements in electrical contact with and optionally disposed within each of the one or more electrically conducting contact rings  130 . These one or more additional contact elements are configured to provide electrical communication between one or more electrically conducting contact rings  130  and a lead contact received within the lead aperture  165 . In many embodiments, these contact elements are electrically conductive and resilient to provide an interference fit between the electrically conducting contact ring  130  and lead contact received within the lead aperture  165 . 
   Examples of contact elements include, but are not limited to, spring elements. In many embodiments, the contact element includes an annular helical coil  150  (i.e., continuous coil spring  150 ) is disposed adjacent an inner surface of the electrically conducting contact ring  130 . The helical annular coil  150  can be formed of any useful electrically conductive material such as, for example, a metal like gold, silver, titanium and the like. When a lead in inserted into the lead aperture  165 , the lead and lead contact(s) can deflect the annular helical coil  150  and form an electrical contact between the lead contact and the electrically conducting contact ring  130 . The continuous coil spring  150  provides a frictional electrical and mechanical engagement with a lead contact and the adjacent electrically conducting contact ring  130 . 
   A mounting flange  160  can be fixed to the lead connector  105  adjacent the open end  166 . The mounting flange  160  can be brazed or welded to the hermetically sealed housing  109 . In many embodiments, the mounting flange  160  is brazed or welded to an exterior surface of the hermetically sealed housing  109 . In other embodiments, the mounting flange  160  is brazed or welded to an interior surface of the hermetically sealed housing  109 . A retention member  190  such as for example, a set screw, can be disposed on the lead connector  105  adjacent to the open end  166  and can assist in mechanical retention of a lead disposed within the lead aperture  165 . 
   The lead connector assembly  101  includes a rigid sleeve  191  disposed about the hermetic lead connector  105  outer surface  170 . The rigid sleeve  191  having an aperture  194  that exposes a portion of the one or more electrically conducting contact rings  130 . The rigid sleeve  191  can be formed of any useful rigid material such as, for example, a metallic material such as titanium or stainless steel. In many embodiments, the rigid sleeve  191  can be formed of an electrically conductive rigid material. The rigid sleeve  191  can be fixed to the interior surface of the hermetically sealed housing  109  and/or fixed to the mounting flange  160 . The rigid sleeve  191  can provide axial compression and cantilever strength to the lead connector  105  and assist in maintaining the hermetic seal formed by the lead connector  105 . In some embodiments, in insulator layer  192  is disposed between the lead connector end cap  145  and the rigid sleeve  191 . The rigid sleeve  191  can aid in reducing a bending moment along the length of the lead connector. 
   In the illustrated embodiment, the rigid sleeve  191  is formed of an electrically conducting metallic material and is electrically isolated from the one or more electrically conducting contact rings  130  since the one or more electrically insulating rings  140  have a larger diameter than the one or more electrically conducting contact rings  130 . In other embodiments, the rigid sleeve  191  is electrically isolated from the one or more electrically conducting contact rings  130  by any useful insulating technique including for example, placing an insulative material between the rigid sleeve and the one or more electrically conducting contact rings  130 . 
   In some embodiments, the lead connector assembly  101  is a filtering lead connector assembly  101  and includes a capacitor  193  or filtering capacitor  193  disposed adjacent to or within the aperture and in electrical connection with the one or more electrically conducting contact rings  130  and the rigid sleeve  191 . The filtering capacitor  193  can filter out EMI and can include one or more contact apertures  195  configured to accept a portion of each of the one or more electrically conducting contact rings  130 , as illustrated. The filtering capacitor  193  active plates can be in electrical communication with a portion of each of the one or more electrically conducting contact rings  130  and the filtering capacitor  193  ground plates can be in electrical communication with the rigid sleeve  191  and/or hermetically sealed housing  109 . 
   The lead connector  105  can be formed by any useful method. In many embodiments, the lead connector  105  is formed by assembling two or more lead connector subassemblies  180 .  FIG. 7  is an exploded perspective cut-away view of the illustrative subassembly  180  shown in  FIG. 6 .  FIG. 8  is a perspective cut-away view of the illustrative subassembly  180  shown in  FIG. 6 . 
   Each lead connector subassembly  180  includes the electrically insulating ring  140  fixed between the electrically conducting contact ring  130  and an attachment ring or electrically conducting spacer ring  175 . Thus, the electrically conducting spacer ring  175  is affixed to a first side of the electrically insulating ring  140  and the electrically conducting contact ring  130  is affixed to a second opposing side of the electrically insulating ring  140 . The lead connector subassembly  180  includes the electrically insulating ring  140  brazed between the electrically conducting contact ring  130  and the electrically conducting spacer ring  175 , leaving braze  176  disposed between the electrically insulating ring  140  and the electrically conducting contact ring  130 , and between the electrically insulating ring  140  and the electrically conducting spacer ring  175 . The braze  176  assists in providing the hermetic seal between the between the sealed housing interior/lead connector outer surface  170  and the lead aperture  165 . To form each subassembly, the electrically insulating ring  140  can be metallized on opposing edges and then the metallized edges are brazed (using braze  176 ) to the electrically conducting contact ring  130 , and attachment ring or electrically conducting spacer ring  175 . 
   The electrically conducting spacer ring  175  can be formed of can be formed of any useful electrically conductive material. In many embodiments, the electrically conducting spacer ring  175  is formed of a metallic material such as, for example, titanium, stainless steel, MP35N, niobium, tantalum, platinum, and alloys or combinations thereof. In some embodiments, the one electrically conducting spacer ring  175  is formed of a metallic material such as, for example, titanium. 
   In one embodiment, each ring subassembly includes an electrically insulating ring formed of a single crystal sapphire material and fixed between an electrically conducting contact ring formed of titanium and an electrically conducting spacer ring formed of titanium. 
   In many embodiments, a fluid seal material  177  is disposed on the exposed braze  176  joints within the lead aperture  165 . The fluid seal material  177  can be any useful fluid sealing material that prevents moisture from contacting the exposed braze  176  joint within the lead aperture  165 . The fluid seal material  177  provides braze joint corrosion protection. Useful fluid sealing material includes, for example, silicone, rubber, polymers, and the like. In many embodiments, the fluid sealing material  177  has a glass transition temperature less than the glass transition temperature of the braze  176 . In embodiments that use non-corrosive braze  176 , a fluid seal material  177  is not utilized. 
   In many embodiments, the brazing process is operated at temperatures above 1000 degrees centigrade. At these elevated temperatures, some elements that form the lead connector, described herein, are damaged, destroyed, or lose physical properties. For example, the contact element coil will lose its temper at brazing temperatures and the fluid and wiper seals will melt at brazing temperatures. Thus, the design and manufacturing method described herein allows for the lead connector elements that can withstand the brazing process only to be subjected to the brazing process and then the other temperature sensitive elements are assembled to form the lead connector. 
     FIG. 9  is a perspective cut-away view of the illustrative subassembly  180  shown in  FIG. 6 .  FIG. 10  is a perspective view of the illustrative subassembly  180  shown in  FIG. 6 . Each subassembly  180  can include additional elements such as, for example, a contact element  151 , a wiper seal  178  or other sealing rings  152 . In the illustrated embodiments, an annular helical coil  150  is disposed within a contact assembly  151  and the contact assembly is disposed within the electrically conducting contact ring  130 . One useful contact assembly is a Bal Seal contact ring assembly available from Bal Seal Engineering Co., Inc., (Foothill Ranch, Calif.) The contact assembly can be welded to the electrically conducting contact ring  130 . This method of fabrication of the individual subassembly  180  allows the body of the subassembly  180  to be brazed together at brazing temperatures and then temperature sensitive components (such as the contact assembly  151 , fluid seal material  177  and wiper seal  178 ) can be installed into the subassembly  180  following the brazing process. 
   The wiper seal or sealing rings can be formed of any useful electrically insulating material, and is often deformable. The wiper seal and sealing rings can assist in electrically isolating adjacent electrically conducting contact rings  130 . Each lead connector subassembly  180  can be welded together in axial alignment using conventional techniques. Thus, a first ring subassembly electrically conducting contact ring is welded to an adjacent second ring subassembly electrically conducting spacer ring. As illustrated, in many embodiments, each ring subassembly has substantially similar dimensions. Thus, the plurality of ring subassemblies can be stacked and fixed in any useful number of ring subassemblies providing a modular design. 
     FIG. 11  is a perspective view of the illustrative lead connector assembly  101  shown in  FIG. 5 .  FIG. 12  is a perspective view of another illustrative lead connector assembly  101  shown in  FIG. 5  including a filtering capacitor  196 . The illustrative lead connector assembly  101  includes a rigid sleeve  191  disposed about the lead connector  105  and providing axial compression to the lead connector  105 . An aperture  194  in the rigid sleeve  191  exposes at least a portion of each of the electrically conducting contact rings  130 , each of the electrically insulating rings  140 , and each of the electrically conducting spacer rings  175 , as illustrated. A filtering capacitor  196  is disposed adjacent to or within the aperture  194  and in electrical connection with the one or more electrically conducting contact rings  130  and the rigid sleeve  191 , as described above. 
   While  FIGS. 5 ,  6 ,  11  and  12  illustrate a lead connector having a single open end as shown in  FIG. 4A , it is understood that a rigid sleeve and/or filtering capacitor, as described herein, can be disposed about at least a portion of the open-ended lead connector shown in  FIG. 4B . 
   These lead connector assemblies are directly coupled to electronics within the housing hermetic seal. Since both the lead connector assembly and the electronics are within the housing hermetic seal, a conventional feedthrough connector or separate lead connector block is not needed to electrically couple the lead connector assembly to the electronics. These features allow the active medical device to be assembled with fewer parts, fewer connections and to form an overall smaller active medical device than a device where the lead connector is not formed within the hermetic seal of the active medical device housing. 
   Thus, embodiments of the HERMETIC LEAD CONNECTOR ASSEMBLY are disclosed. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.