Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority based on provisional applications Serial No. 60/423,787, filed Nov. 5, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The invention relates to a one-piece header assembly for connecting an implantable medical device to a body organ assisted by the medical device. The header assembly includes terminal blocks electrically connected to the distal end of intermediate conductor wires supported in the header. The proximal end of the intermediate conductor wires comprise a quick connect structure for connecting to feedthrough wires or pins exiting the medical device. Electrical leads are plugged into the terminal blocks to establish continuity from the medical device to a tip of the electrical leads inserted into a body tissue.  
           [0004]    2. Prior Art  
           [0005]    Implantable medical devices have feedthrough conductors in the form of pins or wires connected to the internal components of the medical device. The feedthrough wires extend through a wall of the medical device housing and are electrically insulated therefrom by a ceramic-to-metal seal or a glass-to-metal seal. Electrical continuity to a conductor lead attached to the body being assisted is established by connecting intermediate conductor wires supported by a polymeric header mounted on the medical device to the feedthrough wires and terminal blocks in the molded header. The terminal blocks then provide for plugging the conductor lead into the molded polymeric header. Examples of this type of header assembly are shown in U.S. Pat. No. 4,254,775 to Langer, U.S. Pat. No. 4,262,673 to Kinney et al., U.S. Pat. No. 4,764,132 to Stutz, Jr., U.S. Pat. No. 5,282,841 to Szyszkowski and U.S. Pat. No. 5,336,246 to Dantanarayana. However, what is needed is a quick and reliable connection between the feedthrough wires from the medical device and the intermediate conductor wires supported by the molded header. The present invention connection structures are improvements over those shown by the prior art patents.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is, therefore, directed to a header assembly for a medical device. The header assembly provides electrical connection between feedthrough wires extending from inside the medical device to a conductor lead connected to the body organ or tissue being assisted. Several different embodiments of header assemblies are described comprising structures for securing the feedthrough wires from the medical device to conductor wires in the molded header. The conductor wires are, in turn, connected to terminal blocks into which the lead wires from the body tissue are plugged into. 
       
    
    
       [0007]    These features of the present invention will be apparent upon consideration of the following detailed description thereof presented in connection with the following drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is an exploded view of a header assembly  10  mounted on an implantable medical device  18  according to the present invention.  
         [0009]    [0009]FIG. 2 is a perspective view of the header assembly  10  shown in FIG. 1.  
         [0010]    [0010]FIG. 3 is another perspective view of the header assembly shown in FIG. 1.  
         [0011]    [0011]FIG. 4 is a cross-sectional view taken along line  4 - 4  of FIG. 2.  
         [0012]    [0012]FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG. 4.  
         [0013]    [0013]FIG. 6 is a perspective view of an alternate embodiment of an intermediate conductor lead  100 .  
         [0014]    [0014]FIG. 7 is a partial cross-sectional view of the header  16  supporting a plurality of conductor leads  100 ,  106 ,  108  and  110 .  
         [0015]    [0015]FIG. 8 is a cross-sectional view taken along line  8 - 8  of FIG. 7.  
         [0016]    [0016]FIG. 9 is a partial cross-sectional view of header  16  supporting a plurality of intermediate conductor wires  120 ,  132 ,  134  and  136  accordingly to another embodiment of the invention.  
         [0017]    [0017]FIG. 10 is a cross-sectional view of conductor wire  120  and its associated conductor block  122 .  
         [0018]    [0018]FIG. 10A illustrates an alternate embodiment of a conductor wire  121  having a unitary proximal end  121 A supporting a coil spring  128  in an inner annular groove  125  thereof.  
         [0019]    [0019]FIG. 11 is a cross-sectional view taken along line  11 - 11  of FIG. 10.  
         [0020]    [0020]FIG. 11A illustrates an alternate embodiment of an leaf spring  129  supported in an inner annular groove  126  provided at the proximal end of a conductor wire.  
         [0021]    [0021]FIG. 12 is a perspective view of one embodiment of a bracket  142  for securing a polymeric header  140  to the medical device  22 .  
         [0022]    [0022]FIGS. 13 and 14 are side and front elevational views, respectively, showing the header  140  being secured to the medical device  22 .  
         [0023]    [0023]FIG. 15 is a perspective view of another embodiment of a bracket  162  for securing a polymeric header  160  to the medical device  122 .  
         [0024]    [0024]FIGS. 16 and 17 are side and front elevational views, respectively, showing the header  160  being secured to the medical device  22 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Referring now to the drawings, FIGS.  1  to  6  illustrate a header assembly  10  according to the present invention comprising two pairs of terminal blocks  12 A,  12 B and  14 A,  14 B partially surrounded by a header  16  comprising a body of molded polymeric material mounted on a support plate  18 . The support plate  18 , in turn, is mounted on the header portion  20  of an implantable medical device  22 . The terminal block pairs  12 A,  12 B and  14 A,  14 B each provide for connecting the lead  24  for a co-axial conductor wire from the medical device to a body tissue. The implantable medical device  22  is exemplary of any one of a number of known assist devices such as cardiac defibrillators, cardiac pacemakers, drug pumps, neurostimulators, hearing assist devices, and the like.  
         [0026]    The implantable medical device  22  comprises a housing  26  of a conductive material, such as of titanium or stainless steel. Preferably, the medical device housing  26  is comprised of mating clam shells in an overlapping or butt welded construction, as shown in U.S. Pat. No. 6,613,474 to Frustaci et al., which is assigned to the assignee of the present invention and incorporated herein by reference. The housing  26  can also be of a deep drawn, prismatic and cylindrical design, as is well known to those skilled in the art.  
         [0027]    The housing  26  is shown in an exemplary form comprising first and second planar major face walls  28  and  30  joined together by a sidewall  32  and the header  20 . The sidewall  32  curves from one end of the header  20  to the other end and is generally arcuate from face wall  28  to face wall  30 . The preferred mating clam shells of housing  26  are hermetically sealed together, such as by laser or resistance welding, to provide an enclosure for the medical device including its control circuitry  34  and a power supply  36 , such as a battery (the control circuitry and power supply are shown in dashed lines in FIG. 1). The power supply  36  is connected to the control circuitry  34  by electrical leads (not shown). There may also be a capacitor for a medical device such as a defibrillator.  
         [0028]    The header  20  of housing  26  has a planar upper surface  38  providing at least four openings through which respective feedthrough wires  40 ,  42 ,  44 , and  46  pass. The feedthrough wires extend from a distal end positioned inside the housing  26  connected to the control circuitry  34  to respective proximal ends spaced above the header upper surface  38 . The feedthrough wires  40 ,  42 ,  44 , and  46  are electrically insulated from the housing  26  by respective ceramic-to-metal seals or glass-to-metal seals (not shown), as are well known by those skilled in the art.  
         [0029]    As shown in FIG. 3, the terminal block pairs  12 A,  12 B and  14 A,  14 B are aligned in a co-axial relationship and encased in the polymeric material of the molded header  16 . The molded header  16  comprises spaced apart front and back walls  48  and  50  extending to a curved upper wall  52  and a generally planar bottom wall  54 . The bottom wall  54  is supported on the upper surface  56  of support plate  18  and retained in place by encasing a peripheral undercut  58  of the support plate. In an alternate embodiment, the support plate  18  is replaced by a ring (not shown) having either an outer peripheral undercut or an inner peripheral undercut, or both.  
         [0030]    Those skilled in the art will readily understand that the exact shape of the molded header is exemplary. In fact, the molded header can have a myriad of different shapes only limited by the design specifications of the associated medical device and its intended use.  
         [0031]    Each terminal block  12 A,  12 B,  14 A,  14 B has an internal cylindrically shaped bore. The terminal block pairs  12 A,  12 B and  14 A,  14 B have their internal bores aligned along the longitudinal axis of a respective bore  60 ,  62  leading into the polymeric header  16  from the curved upper wall  52 . The structure of the bores  60 ,  62  will be described in detail with respect to the former bore. However, it is understood that a similar structure exists for bore  62 .  
         [0032]    In that respect, the header assembly bore  60  has a first portion  60 A of a first diameter sized to receive a distal portion  24 A of the conductor lead  24 , a second, intermediate portion  60 B of a second, greater diameter sized to receive a proximal portion  24 B of the lead and a third portion  60 C of a still greater diameter than the intermediate portion. Frustoconically shaped portions lead from one bore portion to the next larger bore portion. The terminal blocks  12 A,  12 B have lead openings of diameters somewhat larger than the first and second bore portions  60 A,  60 B so that the conductor lead  24  is received therein in a tight fitting, electrically stable connection.  
         [0033]    As shown in FIG. 4, each terminal block  12 A,  12 B,  14 A and  14 B is connected to an intermediate conductor wire that provides electrical conductivity between the block and its associated feedthrough wires from the medical device. More specifically, intermediate conductor wire  64  is a unitary member having a distal end electrically secured, such as by welding, to the outer wall of terminal block  12 A. This wire  64  has a bend along its length and leads to a proximal end  64 A residing in an inlet  65  in the bottom wall  54  of the header  16 . The intermediate conductor wire  64  has a generally circular cross-section perpendicular to its longitudinal axis except at its proximal end. There, the wire has a step  64 A about halfway through its diameter. The step  64 A provides a lap joint structure for securing the intermediate conductor wire  64  to feedthrough wire  40 , as will be described in detail presently.  
         [0034]    In a similar manner, terminal block  12 B is electrically connected to the distal end of intermediate conductor wire  66 . The proximal end of wire  66  residing in the inlet  65  has a step  66 A. The step  66 A provides a lap joint for securing the intermediate conductor wire  66  to feedthrough wire  42 .  
         [0035]    Terminal block  14 A is electrically connected to the distal end of intermediate conductor wire  68 . The proximal end of wire  68  has a step  68 A residing in inlet  65  for securing the intermediate conductor wire to feedthrough wire  44 .  
         [0036]    Terminal block  14 B is electrically connected to the distal end of intermediate conductor wire  70 . The proximal end of wire  70  has a step  70 A residing in inlet  65  for securing the intermediate conductor wire to feedthrough wire  46 .  
         [0037]    While header  16  is illustrated having two pairs of terminal blocks, this is for illustrative purposes only. Those skilled in the art will realize that the header can have one pair of terminal blocks, or more than two pairs. Also, the terminal blocks need not be provided in pairs. Instead, a header bore can be in communication with only one terminal block, or with more than two aligned blocks.  
         [0038]    Terminal blocks  12 B and  14 B are each provided with respective inner annular grooves  72  and  74 . Respective collapsible coil springs  76 ,  78  are nested in the grooves  72 ,  74  to help ensure that the terminal blocks  12 B,  14 B are electrically connected to the conductor leads  24  received in the bores  60 ,  62 .  
         [0039]    The front wall  48  of the molded header  16  is provided with an oval shaped raised land  80 . A pair of passageways  82  and  84  enter the raised land  80  to communicate with the respective terminal blocks  12 A,  14 A. The passageways  82 ,  84  are aligned perpendicularly with the longitudinal axes of the bores  60 ,  62 . Passageway  82  leads to a threaded aperture  86  (FIGS. 1, 2 and  5 ) in terminal block  12 A that receives a setscrew (not shown). The setscrew contacts the distal portion  24 A of the conductor lead  24  to prevent loss of electrical contact between the lead and the terminal blocks  12 A,  12 B. Similarly, passageway  84  extends to a threaded aperture  88  in the sidewall of terminal block  14 A that receives a setscrew (not shown) to maintain electrical continuity between the lead and the terminal blocks  14 A,  14 B.  
         [0040]    The thusly described molded header  16  is mounted on the medical device  22  with the support plate  18  contacting the upper surface  38  of the header  20 . The support plate  18  has an opening  18 A (FIGS. 1, 2 and  4 ) through which the feedthrough wires  40 ,  42 ,  44  and  46  extend. The support plate  18  and header  20  are both of a conductive metal and welding is typically used to join them together. With the molded header  16  secured to the medical device  22 , the feedthrough wire  40  is of a length to overlap the step  64 A at the proximal end of intermediate conductor wire  64  residing in inlet  65 . Welding the feedthrough wire  40  to the step  64 A of conductor wire  64  then makes electrical connection. In this manner, there are only two connections between the medical device and the terminal block. One is where the feedthrough wire  40  connects to the step  64 A and the other is where the distal end of the intermediate conductor wire  64  connects to the terminal block  12 A.  
         [0041]    A similar electrical connection is made by welding feedthrough wire  42  to step  66 A of conductor wire  66 , feedthrough wire  44  to step  68 A of conductor wire  68  and feedthrough wire  46  to step  70 A of conductor wire  70 . In this manner, electrical continuity is established between the control circuitry  34  of the medical device  22  and the terminal blocks  12 A,  12 B,  14 A and  14 B through respective intermediate conductor wires  64 ,  66 ,  68  and  70 .  
         [0042]    Inlet  65  in the molded header  16  (FIGS.  1  to  4 ) where the feedthrough wires  40 ,  42 ,  44  and  46  and the proximal ends  64 A,  66 A,  68 A and  70 A of the intermediate conductor wires are connected together is then back filled with a polymeric material. A suitable one is a silicon-based material. This prevents body fluids from coming into contact with these electrical connections.  
         [0043]    In use, the medical device is positioned in a body, such as a human or animal, to assist a body function. A suture opening  90  is provided in the molded header  16  to aid in securing the medical device  22  inside the body. The physician then plugs a conductor lead  24  into each bore  60 ,  62  in molded header  16 . The distal end (not shown) of the co-axial conductor opposite that of the lead  24  has already been positioned in a body tissue, such as a heart muscle, for transmitting physiological information to the medical device and for administering a medical theory as needed.  
         [0044]    An example of this is in a cardiac defibrillator where the medical device may monitor the heart rate for extended periods of time. When a potentially fatal irregular, rapid heartbeat known as tachyarrhythmia is detected, the defibrillator delivers an electrical shock to the heart. The electrical shock is transmitted from the control circuitry  34  through the feedthrough wires  40 ,  42 ,  44  and  46  and intermediate conductor wires  64 ,  66 ,  68  and  70 . These conductors are electrically connected to the terminal blocks  12 A,  12 B,  14 A and  14 B into which the conductor leads  24  are plugged.  
         [0045]    FIGS.  6  to  8  show an alternate embodiment of an intermediate conductor wire  100  according to the present invention. Conductor wire  100  is useful in lieu of, or in combination with, the previously described conductor wires  64 ,  66 ,  68  and  70 . For example, terminal blocks  12 A and  12 B could be connected to an intermediate terminal wire of the structure  64  and  66  while terminal blocks  14 A and  14 B could be connected to intermediate conductor wire  100 .  
         [0046]    In any event, conductor wire  100  is preferably a unitary member having a circular cross-section perpendicular to its length extending from a distal end (not shown) electrically secured to a terminal block, for example block  12 A, to an opposite proximal end  10 A. The proximal end  100 A of the conductor wire  100  resides in the inlet  65  of the molded header  16 . The proximal end  100 A comprises a head  102  of a larger diameter than the remaining length of the wire  100 . The head  102  is a cylindrically shaped portion of a length somewhat less than the depth of inlet  65 . A bore  104  is provided in head  102  aligned along the longitudinal axis thereof.  
         [0047]    [0047]FIG. 7 shows the molded polymeric header  16  supporting four conductor wires  100 ,  106 ,  108  and  110  corresponding to the feedthrough wires  40 ,  42 ,  44  and  46 . The feedthrough wires are received inside the bore  104  of head  102  of the conductor wires with the header  16  mounted on the medical device  22 . The conductor wires and feedthrough wires are then joined together such as by welding. A silicon-based material (not shown) is used to backfill inlet  65  in molded header  16 .  
         [0048]    FIGS.  9  to  11  show another embodiment of an intermediate conductor wire  120  according to the present invention. As with conductor wire  100 , conductor wire  120  is useful in lieu of, or along with, the previously described conductor wires. Conductor wire  120  has a circular cross-section perpendicular to its length extending from a distal end (not shown) electrically secured to a terminal block, for example block  12 A, to an opposite proximal end  120 A. The end  120 A resides in the inlet  65  of the molded polymeric header  16  and is received in a bore in a connector block  122 . The conductor wire  120  and connector block  122  are preferably welded together. A coaxial bore  124  extends part way into the length of conductor block  122 . An annular groove  126  provided in the sidewall of bore  124  has an annular coil spring  128  nested therein.  
         [0049]    [0049]FIG. 9 shows the molded header  16  supporting four conductor wires  122 ,  130 ,  132 , and  134  corresponding to the feedthrough wires  40 ,  42 ,  44  and  46 . The feedthrough wires are received inside the bore  124  of the conductor block  122  of each of the conductor wires with the header  16  mounted on the medical device  22 . There is no need to join the conductor wires and feedthrough wires by welding. Instead, the coil spring  128  provided sufficient conductivity between the feedthrough wires and the connector block  122  welded to the end  120 A of the intermediate connector wire  120 . A silicon-based material (not shown) is used to backfill the inlet  65  in the molded header  16 .  
         [0050]    As shown in FIG. 10A, it is further within the scope of the present invention that the conductor wire  120  and connector block  122  are unitary. Conductor wire  121  has a circular cross-section perpendicular to its length extending from a distal end (not shown) electrically secured to a terminal block, for example block  12 A, to an opposite proximal head  121 A. The proximal head  121 A of conductor wire  121  resides in the inlet  65  of the molded polymeric header  16  and includes a coaxial bore  123  extending part ways into its length. An annular groove  125  provided in the sidewall of bore  123  has a coil spring  128  nested therein. In all other respects, conductor wire  121  functions in a similar manner as the previously described wire  120  and connector block  122 .  
         [0051]    It is also within the scope of the present invention that the spring need not be of a coil structure. As shown in FIG. 11A, the annular groove  126  provided in the sidewall of bore  124  supports an annular leaf spring  129  nested therein.  
         [0052]    FIGS.  12  to  14  illustrate an alternate embodiment of a structure for securing a polymeric header  140  to the medical device  22 . Polymeric header  140  is similar to the previously described header  16  except it is not molded to an undercut of a support plate. Instead, the header  20  of the medical device supports an L-shaped bracket  142 , preferably of a metal such as titanium or stainless steel, having an upstanding wall  142 A provided with an elongated slot  144 . The longitudinal axis of slot  144  is parallel to the planar upper surface  56  of the medical device header  20 . The bottom wall  54 A of header  140  is provided with an inlet  146  that matches the shape of bracket  142 . A lateral inlet  148  is provided in the sidewall  150  of header  140  and intersects with inlet  146 . When the molded header  140  is mounted on the medical device  22 , the bracket  142  is received in the inlet  146 . In this position, the lateral inlet  148  is aligned with slot  144 . As shown in FIG. 13, a wedge  152 , preferably of a metal such as that of the bracket  142 , is moved into the lateral inlet  148  and bracket slot  144  to pin or secure the header and medical device together. The wedge can also be of a polymeric material.  
         [0053]    FIGS.  15  to  17  illustrate an alternate embodiment of a structure for securing a polymeric header  160 , similar to the previously described header  140 , to the medical device  22 . The medical device header  20  supports a U-shaped bracket  162 , preferably of a metal such as titanium or stainless steel, having a pair of upstanding sidewalls  162 A and  162 B, each provided with an elongated slot  164 . The longitudinal axes of the slots  164  are parallel to the planar upper surface  56  of the medical device header  20 . The bottom wall  54 B of the molded header  160  is provided with an inlet  166  that matches the shape of bracket  162 . A lateral inlet  168  is provided in the sidewall  170  of header  160  and intersects with inlet  164 . When the header  160  is mounted on the medical device  22 , the bracket  162  is received in the inlet  166 . In this position, the lateral inlet  168  is aligned with slots  164 . As shown in FIG. 16, a metal or polymeric wedge  172  is moved into the lateral inlet  168  and bracket slots  164  to secure the header  160  and medical device  22  together.  
         [0054]    Now, it is therefore apparent that the present invention accomplishes its intended objects. While embodiments of the present invention have been described in detail, that is for the purpose of illustration, not limitation.

Technology Category: 1