Switched diverter circuits for minimizing heating of an implanted lead and/or providing EMI protection in a high power electromagnetic field environment

An active implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits;
• b) an implantable lead comprising at least one leadwire having a length extending between and to a proximal end electrically connected to the medical device including the tissue-stimulating or biological-sensing circuits and an electrode configured for tissue-stimulating or biological-sensing at or near a distal end of the leadwire;
• c) an energy dissipating surface provided by the device housing;
• d) at least one diversion circuit electrically connected to the device housing;
• and
• e) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to electrically connect the leadwire to the tissue-stimulating or biological-sensing circuits for the AIMD in the absence of an MRI B0 static magnetic field and, in the presence of an MRI B static magnetic field, to electrically disconnect the leadwire from the tissue-stimulating or biological-sensing circuits and to connect the leadwire to the energy dissipating surface,
• f) wherein in the presence of an MRI B0 static magnetic field the switch electrically connects the leadwire to the diversion circuit such that:
• i) at relatively high frequencies attendant to the AIMD being subjected to an MRI RF pulse field, the diversion circuit acts as a relatively low impedance circuit between the leadwire to the energy dissipating surface, and
• ii) at relatively low frequencies attendant to the medical device being subjected to an MRI gradient field, the diversion circuit acts as a relatively high impedance circuit between the leadwire and the energy dissipating surface.

An active implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits;
• b) an implantable lead comprising at least one leadwire having a length extending between and to a proximal end electrically connected to the medical device including the tissue-stimulating or biological-sensing circuits and an electrode configured for tissue-stimulating or biological-sensing at or near a distal end of the leadwire;
• c) an energy dissipating surface provided by the device housing;
• d) at least one diversion circuit electrically connected to the energy dissipating surface;
• and
• e) at least one switch that is selectively actuatable in response to programmable telemetry to electrically connect the leadwire to the tissue-stimulating or biological-sensing circuits for the AIMD in the absence of an MRI B0 static magnetic field and, in the presence of an MRI B0 static magnetic field, to electrically connect the leadwire to the diversion circuit connected to the energy dissipating surface,
• f) wherein in the presence of an MRI B0 static magnetic field with the switch electrically connecting the leadwire to the diversion circuit and:
• i) at relatively high frequencies attendant to the AIMD being subjected to an MRI RF pulse field, the diversion circuit acts as a relatively low impedance circuit between the leadwire to the energy dissipating surface, and
• ii) at relatively low frequencies attendant to the medical device being subjected to an MRI gradient field, the diversion circuit acts as an a relatively high impedance circuit between the leadwire and the energy dissipating surface.

An active implantable medical device (AIMD), comprising:

• a) a conductive device housing containing tissue-stimulating or biological-sensing circuits;
• b) an energy dissipating surface provided by the device housing;
• c) at least one frequency variable impedance diversion circuit electrically connected to the device housing;
• and
• d) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to electrically connect a terminal for an implantable lead to the tissue-stimulating or biological-sensing circuits for the AIMD in the absence of an MRI B0 static magnetic field and, in the presence of an MRI B0 static magnetic field, to electrically disconnect the terminal from the tissue-stimulating or biological-sensing circuits and to connect the terminal for the implantable lead to the diversion circuit connected to the energy dissipating surface,
• e) wherein in the presence of a static magnetic field with the switch electrically connecting the terminal to the diversion circuit and:
• i) at relatively high frequencies attendant to the AIMD being subjected to an MRI RF pulse field, the diversion circuit acts as a relatively low impedance circuit between the terminal and the energy dissipating surface, and
• ii) at relatively low frequencies attendant to the AIMD being subjected to an MRI gradient field, the diversion circuit acts as a relatively high impedance circuit between the terminal and the energy dissipating surface.

An implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits at a first electrical switch point;
• b) a second electrical switch point that is electrically connectable to an electrode configured for tissue-stimulating or biological-sensing;
• c) an energy dissipating surface provided by the device housing as a third electrical point;
• and
• d) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to electrically connect the first electrical switch point at the tissue-stimulating or biological-sensing circuits for the AIMD to the second electrical switch point in the absence of an MRI B0 static magnetic field and, in the presence of an MRI B0 static magnetic field, to electrically disconnect the second electrical switch point from the first electrical switch point and to directly short the second electrical, switch point to the third electrical point at the device housing serving as the energy dissipating surface.

A switched diverter circuit for a medical device, the switched diverter circuit comprising:

• a) a magnetic resonance B0 field sensor;
• b) a first conductor that is connectable to an energy dissipating surface for an active implantable medical device (AIMD);
• c) at least one circuit that is electrically connected to an opposite end of the first conductor;
• and
• d) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to:
• i) in the absence of an MRI B0 static magnetic field, electrically connect from a second conductor that is connectable to a lead terminal for an implantable lead to a third conductor that is electrically connectable to tissue-stimulating or biological-sensing circuits for an AIMD, and
• ii) in the presence of an MRI B0 static magnetic field, electrically disconnects the second conductor from the third conductor and electrically connects the second conductor, which is connectable to a lead terminal, to a fourth conductor that is electrically connected to the diversion circuit opposite the first conductor that is electrically connectable to the energy dissipating surface,
• e) wherein in the presence of an MRI B0 static magnetic field with the switch electrically connecting the leadwire to the diversion circuit and:
• i) at relatively high frequencies attendant to the switched diverter circuit being subjected to an MRI RF pulse field, the diversion circuit shorts the leadwire to the energy dissipating surface, and
• ii) at relatively low frequencies attendant to the switched diverter circuit being subjected to an MRI gradient field, the diversion circuit acts as an open circuit between the leadwire and the energy dissipating surface.

A switched diverter circuit, comprising:

• a) a magnetic resonance B0 field, sensor;
• b) a first electrical point that is connectable to an energy dissipating surface provided by a housing for an active implantable medical device (AIMD);
• c) at least one frequency variable impedance diversion circuit that is electrically connected at the first electrical point to the device housing;
• and
• d) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to
• i) in the absence of an MRI B0 static magnetic field, electrically connect from a second electrical switch point that is electrically connectable to an electrode configured for tissue-stimulating or biological-sensing to a third electrical switch point that is electrically connectable to tissue-stimulating or biological-sensing circuits for an AIMD, and
• ii) in the presence of an MRI B0 static magnetic field, electrically disconnects the second electrical switch point from the third electrical switch point and connect from the second electrical switch point to a fourth electrical switch point that is electrically connected to the diversion circuit opposite the first electrical point at the device housing,
• e) wherein in the presence of an MRI B0 static magnetic field the switch electrically connects the second electrical, switch point to the fourth electrical switch point at the diversion circuit such that:
• i) at relatively high frequencies attendant to an MRI RF pulse field, the diversion circuit acts as a relatively low impedance circuit between the fourth electrical switch point to the first electrical point which is electrically connectable to the energy dissipating surface, and
• ii) at relatively low frequencies attendant to an MRI gradient field, the diversion circuit acts as a relatively high impedance circuit between the fourth electrical switch point and the first electrical point which is electrically connectable to the energy dissipating surface.

A switched diverter circuit, comprising:

• a) a first electrical switch point that is electrically connectable to an electrode configured for tissue-stimulating or biological-sensing;
• b) a second electrical switch point as an energy dissipating surface provided by a housing for an active implantable medical device (AIMD);
• and
• c) at least one switch that is actuatable in response to a magnetic resonance B0 field sensor to electrically connect the first electrical switch point to a third electrical switch point that is electrically connectable to tissue-stimulating or biological-sensing circuits for an AIMD in the absence of an MRI B0 static magnetic field and, in the presence of an MRI B0 static magnetic field, to electrically disconnect the first electrical switch point from the third electrical switch point and to directly short the first electrical switch point to the second electrical switch point connectable to an energy dissipating surface, and
• d) wherein during the short circuit condition, the first electrical switch point is disconnected from the third electrical switch point.

An active implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits connected to a first electrical switch point;
• b) a second electrical switch point that is electrically connectable to an electrode configured for tissue stimulating or biological-sensing;
• c) an energy dissipating surface provided by the device housing as a third electrical point;
• d) at least one diversion circuit electrically connecting between a fourth electrical switch point and the third electrical point at the energy dissipating surface;
• and
• e) at least one switch that is selectively actuatable in response to programmable telemetry to electrically connect the second electrical switch point to the tissue-stimulating or biological-sensing circuits for the AIMD in the absence of an MRI static magnetic field and, in anticipation of being in the presence of a static magnetic field, to electrically disconnect the second electrical switch point from the first electrical switch point and to connect the second electrical switch point to the fourth electrical switch point at the diversion circuit connected to the third electrical point at the energy dissipating surface,
• f) wherein with the switch electrically connecting the second electrical switch point to the fourth electrical switch point at the diversion circuit and at relatively high frequencies attendant to the AIMD being subjected to an MRI RF pulse field, the diversion circuit acts as a relatively low impedance circuit from the fourth electrical switch point to the third electrical point at the energy dissipating surface, and
• g) wherein with the switch electrically connecting the second electrical switch point to the fourth electrical switch point, at the diversion circuit and at relatively low frequencies attendant to the AIMD being subjected to an MRI gradient field, the diversion circuit acts as relatively high impedance circuit between the fourth electrical switch point and the third electrical point at the energy dissipating surface.

An active implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits connected to a first electrical switch point;
• b) a second electrical switch point that is electrically connectable to an electrode configured for tissue-stimulating or biological-sensing;
• c) an energy dissipating surface provided by the device housing as a third electrical point;
• d) at least one diversion circuit electrically connecting between a fourth electrical switch point and the third electrical point at the energy dissipating surface;
• and
• e) at least one switch that is selectively actuatable in response to programmable telemetry to electrically connect the second electrical switch point to the tissue-stimulating or biological-sensing circuits for the AIMD in the absence of an MRI static magnetic field and, in anticipation of being in the presence of a static magnetic field, to electrically disconnect the second electrical switch point, from the first electrical switch point and to connect the second electrical switch point to the fourth electrical switch point at the diversion circuit connected to the third electrical point at the energy dissipating surface,
• f) wherein with the switch electrically connecting the second electrical switch point to the fourth electrical switch point at the diversion circuit and at relatively high frequencies attendant to the AIMD being subjected to an MRI RF pulse field, the diversion circuit acts as a short from the fourth electrical switch point to the third electrical point at the energy dissipating surface, and
• g) wherein with the switch electrically connecting the second electrical switch point to the fourth electrical switch point at the diversion circuit and at relatively low frequencies attendant to the AIMD being subjected to an MRI gradient field, the diversion circuit acts as an open circuit between the fourth electrical switch point and the third electrical point at the energy dissipating surface.

An implantable medical device (AIMD), comprising:

• a) a conductive device housing for the AIMD, the housing containing tissue-stimulating or biological-sensing circuits at a first electrical switch point;
• b) a second electrical switch point that is electrically connectable to an electrode configured for tissue-stimulating or biological-sensing;
• c) an energy dissipating surface provided by the device housing as a third electrical point;
• and
• d) at least one switch that is selectively actuatable in response to programmable telemetry to electrically connect the first electrical switch point at the tissue-stimulating or biological-sensing circuits for the AIMD to the second electrical switch point in the absence of a static magnetic field and, in anticipation of being in the presence of a static magnetic field, to electrically disconnect the second electrical switch point from the first electrical switch point and to directly short the second electrical switch point to the third electrical point at the device housing serving as the energy dissipating surface.