Patent ID: 8447414

Claim:
An active implantable medical device, comprising: a) a conductive device housing for the medical device, 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 connected between the second electrical switch point and the third electrical point at the device housing providing the energy dissipating surface; and e) at least one switch that is actuatable in response to a magnetic resonance B 0 field sensor that, in the absence of a static magnetic field, electrically connects the first electrical point at the tissue-stimulating or biological-sensing circuits to the second electrical switch point and, in the presence of a static magnetic field, electrically disconnects the first electrical point from the second electrical switch point and electrically connects the first electrical switch point to the third electrical point at the device housing in the presence of a static magnetic field, f) wherein regardless the position of the switch: i) at relatively high frequencies attendant to the medical device being in the presence of an RF pulse field, the diversion circuit acts as a relatively low impedance circuit from the second electrical switch point to the third electrical point at the energy dissipating surface, and ii) at relatively low frequencies attendant to the medical device being in the presence of an MRI gradient field, the diversion circuit acts as a relatively high impedance circuit between the second electrical switch point and the third electrical point at the energy dissipating surface.