US 20060015150 A1
The present invention is directed to a header assembly attachable to a medical device for the purpose of connecting its output terminals to at least one lead, the lead terminating at a target organ or portion of the body intending to be assisted. A number of leads are connectable to the header, including single and coaxial leads. The header assembly may be molded directly to the medical device or performed and then attached to the device casing, either by mechanical fastener and/or chemical adhesive.
1. A method for connecting an implantable medical device to a conductor terminating at a body organ intended to be assisted by the medical device, comprising the steps of:
a) providing the medical device having a housing containing control circuitry, at least one electrical energy storage device and at least a first and second feedthrough wires extending from the control circuitry through a wall of the housing to first and second distal ends located outside the housing;
b) connecting the first and second distal ends of the first and second feedthrough wires to respective first and second terminals, wherein the terminals includes first and second lead openings aligned in a first co-axial relationship; and
c) molding a body of polymeric material secured to the wall of the housing with the body having a bore communicating from outside the body to the first co-axial first and second lead openings of the terminals.
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1. Field of the Invention
The invention relates to a one-piece header assembly for connecting implantable medical devices to a body organ intended to be assisted by the medical device. The header assembly includes terminal blocks that connect directly to feedthrough wires extending from inside the medical device to a conductor leading to the body organ or tissue being assisted.
2. Prior Art
Header assemblies for implantable medical devices generally comprise 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, such as a lid, and are electrically insulated therefrom by a ceramic-to-metal seal, and the like. Electrical continuity is established by connecting intermediate conductor wires between the feedthrough wires and connector blocks in the header assembly. Examples of this type of header assembly are shown in the 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.
The intermediate conductor wires represent an electrical connection that could fail through improper connection, corrosion, breakage, and the like. The header assemblies of the present invention eliminate the intermediate conductors. Instead, the feedthrough wires from the medical device connect directly to terminal blocks in the header assembly. This is a more reliable construction than those of the conventional designs.
The present invention is, therefore, directed to a header assembly for a medical device. The header assembly serves as a structure supporting the electrical connection between feedthrough wires extending from inside the medical device to a conductor connected to the body organ or tissue being assisted. Several different embodiments of header assemblies are described including those that are molded directly onto the lid of the medical device and pre-molded ones that are later secure to the medical device. In either case, the present header assemblies include terminal blocks that connect directly to the feedthrough wires coming from the medical device. This eliminates the need for an intermediate conductor wire connecting between the feedthrough wires and the terminal blocks as in the prior art devices.
These features of the present invention will be apparent upon consideration of the following detailed description thereof presented in connection with the following drawings.
Referring now to the drawings, FIGS. 1 to 7 illustrate a header assembly 10 according to the present invention comprising at least one pair of terminal blocks 12 and 14 partially surrounded by a molded polymeric header 16 connected to an implantable medical device 18. The terminal blocks 12, 14 provide for connecting a co-axial conductor 20 from the medical device to a body tissue. The implantable medical device 18 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.
The implantable medical device 18 is contained in a housing 22 of a material such as of stainless steel, and is shown in an exemplary form comprising first and second main clamshell portions 24 and 26. The clamshells 24 and 26 are mated together and hermetically sealed about their periphery to provide an enclosure for the medical device including its control circuitry 28 and a power supply 30 such as a battery (
In particular, the first clamshell 24 comprises spaced apart sidewalls 36 and 38 extending to and meeting with end wall 40. The sidewalls 36, 38 and the end wall 40 meet each other at rounded corners and extend to a front wall 42. Opposite the front wall 42 is a peripheral edge 44 of sidewalls 36, 38 and end wall 40 while opposite the end wall 40 is an opening 46.
The second clamshell 26 comprises spaced apart sidewalls 48 and 50 (
The benefit of having a lap joint construction for the mating clam shells 24 and 26 is that when they are hermetically sealed together, such as by laser welding, the laser beam is prevented from compromising the control circuitry 28 and power supply 30 of the medical device. With a coplanar or butted seam construction (not shown), it is possible for the laser beam to penetrate past the junction of the peripheral edges 44, 56 of the clam shells 24, 26 to compromise the internal device components or power supply housed therein. If a butt-welded construction is used, a backing ring (not shown) is desired. An example of a backing ring for a butt weld construction is shown in
A lid 62 is hermetically sealed to the opening 60 of the mated clamshells 24, 26. The lid 62 consists of spaced apart upper and lower surfaces 64 and 66 extending to and meeting with a surrounding edge 68 (
While the medical device is shown being contained inside a housing of mating clamshells 24, 26, the present invention is not intended to be so limited. Other types of housings such as prismatic, deep drawn, cylindrical are also contemplated.
As shown in
The lid 62 further comprises at least two openings 76 and 78 through which respective feedthrough wires 80 and 82 pass. The feedthrough wires extend from a distal end positioned inside the housing 22 connected to the control circuitry 28 for the medical device 18 to respective proximal ends disposed generally parallel to and spaced above the upper surface 64 of the lid 62. The feedthrough wires 80, 82 are electrically insulated from the lid 62 by respective ceramic-to-metal seals or glass-to-metal seals 84 and 86.
The proximal end of feedthrough wire 80 is connected to the first terminal block 12 supported thereon while the other feedthrough wire 82 is connected to a second terminal block 14 depending therefore. The terminal blocks 12, 14 are ring-shaped members of different diameters, sized to be in electrical contact with matching portions of the lead 88 for a co-axial conductor 90, as will be described in detail hereinafter.
As shown in
In that respect, the header assembly bore 92 has a first portion 102 of a first diameter sized to receive a distal portion 104 of the conductor lead 88, a second, intermediate portion 106 of a second, greater diameter sized to receive a proximal portion 108 of the lead 88 and a third portion 110 of a still greater diameter than the intermediate portion. The terminal blocks 12, 14 have lead openings of diameters somewhat larger than the first and second bore portions 102, 106 so that the conductor lead 88 is received therein in a tight fitting, electrically stable connection.
The front wall 94 of the molded header 16 is provided with a pair of passageways 112 and 114 aligned perpendicularly with the longitudinal axis of the bore 92. Passageway 112 extends to a threaded aperture 116 in the sidewall of terminal block 12 to provide for communication with the first bore portion 102. The passageway and aperture threadingly receive a setscrew 118 that contacts the distal portion 104 of the conductor lead 88 to prevent loss of electrical contact between the lead and the terminal block 12. Similarly, passageway 114 extends to a threaded aperture 120 in the sidewall of terminal block 14 to provide for communication with the second bore portion 106. A setscrew 122 is received therein to contact the proximal portion 108 of the conductor lead 88, thereby maintaining electrical continuity between the lead and the terminal block 14.
An annular channel surrounds the third bore portion 110 for capturing an O-ring 124 therein. This helps to prevent body fluids and the like from contacting the conductor portions 104 and 108 received in the respective terminal blocks 12 and 14. A raised seal 126 further helps prevent body fluids from contacting the co-axial conductor lead 88. Finally, the header assembly 10 is provideD with a suture bore 128 adjacent to the conductor lead bore 92. The suture bore 128 aids a physician in securing the medical device inside a body.
As known in the art, the end (not shown) of the co-axial conductor 90 opposite that of the lead 88 is 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. An example of this is in a cardiac defibrillator where the medical device may monitor the heart rate for extended periods of time. Then, when a potentially fatal irregular, rapid heartbeat known as tachyarrhythmia is detected, the defibrillator delivers an electrical shock to the heart through the lead 88 and conductor 90.
In this respect, the header assembly 150 is similar to the header assembly 10 of FIGS. 1 to 8 except there are two pairs of terminal blocks instead of one. Those skilled in the art will understand that a header assembly according to the present invention can have terminal blocks in addition to the one or two pairs shown. There can be three, four or more pairs. Additionally, it may be desired to have a header assembly where a bore only communicates with one terminal block that is not in a co-axial relationship with a second terminal block.
However, the header assembly 150 differs from the header assembly 10 in that it is not secured to the housing lid 168 by anchors. Instead, header assembly 150 is mounted to the lid 168 by an adhesive material 180, and the like. As shown in
In that respect the feedthrough wires 172, 174 are received in the passageways 182, 184 to contact respective terminal blocks 152, 154 when the header assembly 150 is supported on the lid 168. A laser beam as a joining device is then directed through the side passageways 186, 188 to weld the feedthrough wires in place, electrically contacted to the terminal blocks. Other joining means are contemplated such as soldering, brazing, epoxy, and the like.
A co-axial conductor 164 is then inserted into the header assembly 150 in electrical contact with the terminal blocks, as previously discussed with respect to header assembly 10 shown in FIGS. 1 to 7. The lead of the co-axial conductor 164 is retained in place in the terminal blocks by respective set screws 190 extending through passageways 186, 188 and apertures in the side walls of the terminal blocks to contact the conduction leads.
Another distinction between the header assemblies 10 and 150 is the method of closing the housing for the medical device in the latter embodiment. In the case of header assembly 150, the feedthrough wires are connected to the terminal blocks before being connected to the medical device circuitry. This necessitates that the hermetic housing be constructed by first mounting the lid 168 on one of the clamshells 24, 26. The header assembly 150 is then secured to the lid 168 such as by adhesive, and the like. Next, the feedthrough wires are connected to the internal components of the medical device. Finally, the other clamshell is mated to the first clam shell and sealed thereto to complete the hermetic housing. A suture bore 192 is also provided.
The header is provided with a pair of spaced apart inlets 212 and 214 sized and positioned to receive the lugs 202, 206. The header assembly 200 is further provided with through bores 216 and 218 that align with the apertures 208, 210 when the header assembly is positioned on the lid 202. As the header assembly 200 is positioned on the lid 202, feedthrough wires 220 and 222 previously connected to the terminal blocks (not shown) by welding through setscrew passageways (not shown) are received in respective openings 224, 226 in the lid. As in the other header assembly embodiments, the wires 220, 222 are insulated from the lid by ceramic-to-metal seals 228, 230, and the like. Pins 232 and 234 are then inserted into the respective through bores 216, 218 and apertures 208, 210 to complete the connection. Preferably, the exposed ends of the pins are sealed by a polymeric plug, such as a silicon septum plug, and the like, to prevent them from working loose and to provide a smooth outer surface for the header assembly.
The second mold portion 254 includes posts 258 and 260 on which respective terminal blocks 262 and 264 are supported. When the molding process is complete, the posts 258 and 260 coincide with the passageways through which the welds between the feedthrough wires and the terminal blocks are made for header assemblies 150 and 200, and the apertures which receive set screws for securing the electrical connection between the lead of a co-axial conductor and the terminal blocks for all of the present invention header assemblies.
A pin 266 having the shape of the lead of a co-axial conductor is positioned in the second mold portion 254 received in the respective terminal blocks 262 and 264. Inserts 268 and 270 are supported on the second mold portion 254 abutting the shaped pin 266 from the back of the molded portion, i.e., that portion of the mold lying in the plane of the paper for
The closed book mold 250 is provided with a channel 278 which mates with the barrel of a molding machine (not shown) to inject a charge of polymeric material therein to form the header assembly. Various polymeric materials are contemplated by the scope of the present invention including high durometer polyurethane or polysulfane resins.
FIGS. 17 to 19 illustrate another embodiment of a terminal 340 comprising a cylinder 342 supporting at least one leaf spring 344. The cylinder 342 has an opening 346 aligned along a bore 348 for receiving the lead 350 of a conductor. The opposed ends 352 and 354 of the cylinder are crimped to retain the leaf spring in place, disposed parallel to the longitudinal axis of the bore 348. When the lead is moved along the bore 348 and into the terminal 340, the leaf spring 344 deflects to exert a biasing force on the lead captured therein. The ends of the leaf spring are captured in the cylinder such that the spring does not misalign as the lead moves into and out of the cylinder 342 and bore 348. This terminal eliminates the need for a setscrew, although one can be used if desired. A feedthrough wire 356 is connected to the terminal supported in a body of polymeric material 358.
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.