Abstract:
A bandstop filter includes a capacitance in parallel with an inductance and is placed in series with the implantable lead of an active implantable medical device, wherein values of capacitance and inductance are selected such that the bandstop filter attenuates RF current flow at a selected center MRI RF pulsed frequency or across a range of frequencies. The Qi of the inductor and the Qc of the capacitor are controlled to reduce the overall Q of the bandstop filter to attenuate current flow through the implantable lead along a range of selected frequencies. In a preferred form, the bandstop filter is integrated into a Tip and/or Ring electrode for the active implantable medical device.
Abstract:
A system is provided for identifying implanted medical devices, leads and systems, as well as objects in close proximity to a patient having an implanted active medical device, using a radio frequency identification (RFID) tag having retrievable information relating to the AIMD, lead system and/or patient. An RFID tag communicator includes a circuit for limiting the total continuous transmit time of an interrogation signal, and a time-out circuit for delaying a second and any subsequent interrogation of the RFID tag.
Abstract:
An energy management system facilitates the transfer of high frequency energy coupled into an implanted abandoned lead at a selected RF frequency or frequency band, to an energy dissipating surface. This is accomplished by conductively coupling the implanted abandoned lead to the energy dissipating surface of an abandoned lead cap through an energy diversion circuit including one or more passive electronic network components whose impedance characteristics are at least partially tuned to the implanted abandoned lead's impedance characteristics.
Abstract:
An energy management system that facilitates the transfer of high frequency energy induced on an implanted lead or a leadwire includes an energy dissipating surface associated with the implanted lead or the leadwire, a diversion or diverter circuit associated with the energy dissipating surface, and at least one switch for diverting energy in the implanted lead or the leadwire through the diversion circuit to the energy dissipating surface. In alternate configurations, the switch may be disposed between the implanted lead or the leadwire and the diversion circuit, or disposed so that it electrically opens the implanted lead or the leadwire when diverting energy through the diversion circuit to the energy dissipating surface. The switch may comprise a single or multi-pole double or single throw switch. The diversion circuit may be either a high pass filter or a low pass filter.
Abstract:
A TANK filter is provided for a lead wire of an active medical device (AMD). The TANK filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the TANK filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the TANK filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the TANK filter is integrated into a TIP and/or RING electrode for an active implantable medical device.
Abstract:
An implantable radio frequency identification (RFID) tag includes a hermetically sealed biocompatible container, an RFID microelectronics chip is disposed within the container, and a biocompatible antenna extends from the RFID microelectronic chip and exteriorly of the container. In an exemplary embodiment the container comprises a housing for an active implantable medical device (AIMD). In another exemplary embodiment the RFID tag is associated with an AIMD. The AIMD may comprise a lead system. The RFID tag may be disposed within a non-hermetically sealed portion of the AIMD, such a header block, and may include information pertaining to the AIMD. Another exemplary embodiment may include a sensor conductively coupled to the RFID microelectronics chip. The sensor may be disposed exterior of or within the container. The sensor measures properties and activities of the human body and the RFID tag is capable of transmitting said measured properties in real time.
Abstract:
A system for identifying active implantable medical devices (AIMD) and lead systems implanted in a patient using a radio frequency identification (RFID) tag having retrievable information relating to the AIMD, lead system and/or patient. The RFID tag may store information about the AIMD manufacturer, model number, serial number; leadwire system placement information and manufacturer information; MRI compatibility due to the incorporation of bandstop filters; patient information, and physician and/or hospital information and other relevant information. The RFID tag may be affixed or disposed within the AIMD or leadwires of the lead system, or surgically implanted within a patient adjacent to the AIMD or leadwire system.
Abstract:
A one-piece cylindrical bandstop filter for medical lead systems incorporates parallel capacitive and inductive elements in a compact cylindrical configuration. The compact cylindrical configuration of the bandstop filter does not add significantly to the size or weight of the medical lead system. Preferably, the bandstop filters are of biocompatible materials or hermetically sealed in biocompatible containers. The parallel capacitive and inductive elements are placed in series with the medical lead system, and are selected so as to resonate at one or more selected frequencies, typically MRI pulsed frequencies.
Abstract:
A bandstop filter having optimum component values is provided for a lead of an active implantable medical device (AIMD). The bandstop filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the implantable lead of the AIMD, wherein values of capacitance and inductance are selected such that the bandstop filter is resonant at a selected frequency. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the bandstop filter to attenuate current flow through the implantable lead along a range of selected frequencies.
Abstract:
A feedthrough terminal assembly for an active implantable medical device (AIMD) includes a plurality of leadwires extending from electronic circuitry of the AIMD, and a lossy ferrite inductor through which the leadwires extend in non-conductive relation for increasing the impedance of the leadwires at selected RF frequencies and reducing magnetic flux core saturation of the lossy ferrite inductor through phase cancellation of signals carried by the leadwires. A process is also provided for filtering electromagnetic interference (EMI) in an implanted leadwire extending from an AIMD into body fluids or tissue, wherein the leadwire is subjected to occasional high-power electromagnetic fields such as those produced by medical diagnostic equipment including magnetic resonance imaging.