Band stop filter employing a capacitor and an inductor tank circuit to enhance MRI compatibility of active medical devices

A lead wire system for use with an active implantable medical device, the lead wire system comprising:

• a) an implantable lead comprising at least one lead wire having a length extending to and meeting with a proximal lead end and a distal lead end;
• b) a tank filter as a permanently passive component circuit electrically connected in series with the lead wire somewhere along the length thereof, the tank filter comprising a capacitor segment having a capacitor segment first end and a capacitor segment second end, and an inductor segment having an inductor segment first end and an inductor segment second end, wherein the capacitor segment first end is electrically connected to the inductor segment first end, and the capacitor segment second, end is electrically connected to the inductor segment second end so that the inductor and the capacitor are electrically coupled to one another in parallel;
• c) wherein the inductor segment has an inductor segment inductance and an inductor segment series resistance (RL), wherein at low frequencies of about 10 Hz to about 1 kHz an inductor segment reactance and the inductor segment series resistance permit passage of biological signals, and the capacitor segment has a capacitor segment capacitance and a capacitor segment series resistance (RC), wherein at low frequencies of about 10 Hz to about 1 kHz a capacitor segment reactance and the capacitor segment series resistance substantially act as an open circuit to the same biological signals that the inductor segment is allowing to pass;
• and
• d) wherein the inductor segment resistance, the inductor segment inductance, the capacitor segment capacitance, and the capacitor segment resistance result in the tank filter being tuned to a resonant center frequency and having a 3 db bandwidth in the Megahertz frequency range.

An active implantable medical device lead wire system, which comprises:

• a) an implantable lead comprising at least one lead wire having a length extending to and meeting with a proximal lead end and a distal lead end;
• b) a tank filter as a permanently passive component circuit comprising a capacitor segment having a capacitor segment first end and a capacitor segment second end, and an inductor segment having an inductor segment first end and an inductor segment second end, wherein the capacitor segment first end is electrically connected to the inductor segment first end, and the capacitor segment second end is electrically connected to the inductor segment second end so that, the inductor and the capacitor are electrically coupled to one another in parallel;
• c) wherein the inductor segment has an inductor segment inductance and an inductor segment series resistance (RL), wherein at low frequencies of about 10 Hz to about 1 kHz an inductor segment reactance and the inductor segment series resistance permit passage of biological signals, and the capacitor segment has a capacitor segment capacitance and a capacitor segment series resistance (RC), wherein at low frequencies of about 10 Hz to about 1 kHz a capacitor segment reactance and the capacitor segment series resistance substantially act as an open circuit to the same biological signals that the inductor segment is allowing to pass;
• d) wherein the inductor segment resistance, the inductor segment inductance, the capacitor segment capacitance, and the capacitor segment resistance result in the tank filter having a Q wherein the resultant 3 db bandwidth is on the order of megahertz;
• and
• e) wherein the tank filter is in series with the lead wire with the capacitor segment first end and the inductor segment first end being directly and electrically conductively connected to the distal end of the lead wire and the capacitor segment second end and the inductor segment second end being electrically conductively coupled to an electrode.

An active implantable medical device lead wire system, which comprises:

• a) an implantable lead comprising at least one lead wire having a length extending to and meeting with a proximal lead end and a distal lead end;
• b) a tank filter as a permanently passive component circuit comprising a capacitor segment having a capacitor segment first end and a capacitor segment second end, and an inductor segment having an inductor segment first end and an inductor segment second end, wherein the capacitor segment first end is electrically connected to the inductor segment first end, and the capacitor segment second end is electrically connected to the inductor segment second end so that the inductor and the capacitor are electrically coupled to one another in parallel;
• c) wherein the inductor segment has an inductor segment inductance and an inductor segment series resistance (RL), wherein at low frequencies of about 10 Hz to about 1 kHz an inductor segment reactance and the inductor segment series resistance permit passage of biological signals, and the capacitor segment has a capacitor segment capacitance and a capacitor segment series resistance (RC), wherein at low frequencies of about 10 Hz to about 1 kHz a capacitor segment reactance and the capacitor segment series resistance substantially act as an open circuit to the same biological signals that the inductor segment is allowing to pass;
• c) wherein the inductor segment resistance, the inductor segment inductance, the capacitor segment capacitance, and the capacitor segment resistance result in the tank filter having a Q wherein the resultant 3 db bandwidth is on the order of megahertz;
• and
• wherein the tank filter is in series with the lead wire with the capacitor segment first end and the inductor segment first, end being directly and electrically conductively connected to the proximal end of the lead wire, and the capacitor segment second end and the inductor segment second end being electrically conductively connectable to an external portion of a terminal pin of a hermetic seal.