Filter circuit for an active implantable medical device

Abstract

A shielded three-terminal flat-through EMI/energy dissipating filter includes an active electrode plate through which a circuit current passes between a first terminal and a second terminal, a first shield plate on a first side of the active electrode plate, and a second shield plate on a second side of the active electrode plate opposite the first shield plate. The first and second shield plates are conductively coupled to a grounded third terminal. In preferred embodiments, the active electrode plate and the shield plates are at least partially disposed with a hybrid flat-through substrate that may include a flex cable section, a rigid cable section, or both.

What is claimed is: 
     
         1 . A filter circuit for an active implantable medical device, comprising:
 a) an active implantable medical device (AIMD) comprising an electrically or thermally conductive housing and a hermetic feedthrough terminal;   b) an AIMD electronic circuit disposed within the conductive housing;   c) a conductor electrically coupling through the hermetic feedthrough terminal in nonconductive relation to the conductive housing and electrically coupled to the AIMD electronic circuit, the conductor defined as comprising a first node and a second node disposed in series along the conductor, the first node disposed closer to the hermetic feedthrough terminal and the second node disposed closer to the AIMD electronic circuit, the conductor further defined as comprising a first length between the hermetic feedthrough terminal and the first node, a second length between the first node and second node, a third length between the second node and the AIMD electronic circuit;   d) a frequency selective energy diversion circuit configured to divert high-frequency MRI energy away from the conductor to the conductive housing for dissipation of high-frequency MRI energy, the diversion circuit electrically connected between the first node and the conductive housing;   e) an impeding circuit configured to raise the high-frequency impedance of the conductor, the impeding circuit electrically connected in series along the second length of the conductor disposed between the first and second nodes;   f) a broadband low pass filter for attenuating RF energy connected along the third length, wherein the broadband low pass filter comprises a capacitor, an “L” filter, a “T” filter, a “n” filter, a “LL” filter, a “5 element” filter or an “n” element filter; and   g) wherein the first length of the conductor is disposed between a first and second shield plate   
     
     
         2 . The filter circuit of  claim 1  wherein the diversion circuit comprises a capacitor, a parasitic capacitance or an L-C trap filter. 
     
     
         3 . The filter circuit of  claim 1  wherein the diversion circuit comprises a capacitor and an LC trap filter. 
     
     
         4 . The filter circuit of  claim 1  wherein the impeding circuit comprises an inductor or a bandstop filter. 
     
     
         5 . The filter circuit of  claim 1  wherein the diversion circuit, impeder circuit and broadband low pass filter are disposed within the conductive housing protected from direct contact with patient body fluid. 
     
     
         6 . An energy dissipating filter for an implantable medical device, comprising:
 a) an implantable lead defined as comprising a length between a proximal end and a distal end;   b) at least one conductor disposed along the length of the lead;   c) at least one electrode contactable to biological cells disposed at the distal end of the lead and electrically coupled to the at least one conductor;   d) an energy dissipating surface disposed along a portion of the lead;   e) a frequency selective energy diversion circuit configured to divert a high-frequency MRI energy away from the lead to the energy dissipating surface for dissipation of high-frequency MRI energy, the diversion circuit electrically connected between the at least one electrode and the energy dissipating surface;   f) an impeding circuit configured to raise the high-frequency impedance of the lead or at least one conductor, the impeding circuit electrically connected in series along the at least one conductor disposed between the diversion circuit and proximal end;   g) a broadband low pass filter for attenuating RF energy connected along the at least one conductor between the impeding circuit and the proximal end, wherein the broadband low pass filter comprises a capacitor, an “L” filter, a “T” filter, a “π” filter, a “LL” filter, a “5 element” filter or an “n” element filter; and   h) wherein at least a portion of the at least one conductor is sandwiched between a first and second shield plate.   
     
     
         7 . The filter circuit of  claim 6  wherein the diversion circuit comprises a capacitor, a parasitic capacitance or an L-C trap filter. 
     
     
         8 . The filter circuit of  claim 7  wherein the diversion circuit comprises a capacitor and an L-C trap filter. 
     
     
         9 . The filter circuit of  claim 8  wherein the impeding circuit comprises an inductor or a bandstop filter. 
     
     
         10 . A filter circuit for an active implantable medical device, comprising:
 a) an active implantable medical device (AIMD) comprising an electrically or thermally conductive housing and a hermetic feedthrough terminal;   b) an AIMD electronic circuit disposed within the conductive housing;   c) a conductor electrically coupling through the hermetic feedthrough terminal in nonconductive relation to the conductive housing and electrically coupled to the AIMD electronic circuit, wherein a portion of the conductor is disposed between a first and second shield plate, the conductor defined as comprising a first length between a first node to a second node, and a second length between the second node and a third node, wherein the first node is at or near the hermetic feedthrough terminal and the third node is at or near the AIMD electronic circuit;   d) a parasitic capacitance along the first length;   e) a frequency selective energy diversion circuit configured to divert high-frequency MRI energy away from the conductor to the conductive housing for dissipation of high-frequency MRI energy, the diversion circuit electrically connected between the second node and the conductive housing; and   f) an electromagnetic interference filter configured to attenuate RF energy connected to the conductor along the second length.   
     
     
         11 . The filter circuit of  claim 10  wherein the electromagnetic interference filter comprises a capacitor, an inductor, an “L” filter, a “π” filter, a “T” filter, a “LL” filter, a “5 element” filter, an “n” element filter, an L-C trap filter or a bandstop filter. 
     
     
         12 . The filter circuit of  claim 10  wherein the diversion circuit comprises a capacitor or an L-C trap filter. 
     
     
         13 . The filter circuit of  claim 10  wherein the parasitic capacitance is formed by the first length being disposed between the first and second shield plates. 
     
     
         14 . The filter circuit of  claim 10  including back-to-back diodes electrically coupled between the third node and the conductive housing. 
     
     
         15 . A filter circuit for an active implantable medical device, comprising:
 a) an active implantable medical device (AIMD) comprising an electrically or thermally conductive housing and a hermetic feedthrough terminal;   b) an AIMD electronic circuit disposed within the conductive housing;   c) a conductor electrically coupling through the hermetic feedthrough terminal in nonconductive relation to the conductive housing and electrically coupled to the AIMD electronic circuit, wherein a portion of the conductor is disposed between a first and second shield plate, the conductor defined as comprising a first length between a first node to a second node, and a second length between the second node and a third node, wherein the first node is at or near the hermetic feedthrough terminal and the third node is at or near the AIMD electronic circuit;   d) a parasitic capacitance along the first length wherein the parasitic capacitance is formed by the first length being disposed between the first and second shield plates;   e) at least one impeder electrically coupled in series along the conductor; and   f) at least one diverter electrically coupled between the conductor and the AIMD housing.   
     
     
         16 . The filter circuit of  claim 15  including at least one broadband low pass filter connected along the conductor. 
     
     
         17 . The filter circuit of  claim 16  wherein the broadband low pass filter comprises a capacitor, an “L” filter, a “π” filter, a “T” filter, a “LL” filter, a “5 element” filter, an “n” element filter. 
     
     
         18 . The filter circuit of  claim 15  wherein the impeder comprises an inductor or a bandstop filter. 
     
     
         19 . The filter circuit of  claim 15  wherein the diverter comprises a parasitic capacitance, a capacitor or an L-C trap filter. 
     
     
         20 . The filter circuit of  claim 15  including at least one diode connected between the conductor and the AIMD housing.