MRI COMPATIBLE MEDICAL LEADS
Herein is disclosed a probe, including a first electrode disposed at least partially on the probe surface, a second electrode disposed at least partially on the probe surface, a first conductor electrically coupled to the first electrode, a second conductor electrically coupled to the second electrode, and a reactive element electrically coupling the first conductor and the second conductor.
1 . An MRI compatible lead, comprising:
at least one elongate conductor comprising at least one coiled segment defining an inductor;
at least one electrode in electrical communication with the at least one conductor;
and
at least one frequency dependent circuit in communication with the at least one conductor, the at least one frequency dependent circuit comprising the inductor defined by the coiled conductor segment, wherein the coiled segment inductor resides upstream of the at least one electrode, and wherein the at least one frequency dependent circuit is configured to have a high impedance at an MRI scanner operating frequency in the MHz frequency range to thereby inhibit unwanted MRI related RF-induced tissue heating by the at least one electrode.
2 . An MRI compatible lead according to claim 1 , wherein the at least one frequency dependent circuit is also configured to allow at least one of: (a) energy in the KHz range to be delivered along the conductor to the at least one electrode, then to local tissue; and (b) the at least one electrode to detect electrophysiology signals at a low frequency and transmit the detected signals along the conductor to a receiver.
3 . An MRI compatible lead according to claim 1 , wherein the conductor coiled segment resides at a distal portion of the lead.
4 . An MRI compatible lead according to claim 1 , wherein the at least one conductor comprises an insulated wire.
5 . An MRI compatible lead according to claim 1 , wherein the frequency dependent circuit comprises a shielded parallel resonant LC circuit substantially tuned to the MRI scanner operating frequency residing at a distal portion of the conductor.
6 . An MRI compatible lead according to claim 1 , wherein the at least one elongate conductor is a plurality of spaced apart insulated conductors, each comprising at least one coiled segment defining a respective inductor, and wherein the at least one electrode is a plurality of electrodes, each electrode connected to at least one of the conductors.
7 . An MRI compatible lead according to claim 3 , wherein the frequency dependent circuit has an inductor is in series with the at least one electrode.
8 . An MRI compatible lead according to claim 1 , wherein the at least one conductor comprises first and second axially extending conductors, each with at least one coiled segment defining an inductor, wherein the first and second conductors are electrically connected in parallel to a capacitor extending between the first and second conductors at a distal portion of the lead.
9 . An MRI compatible lead according to claim 1 , wherein the at least one conductor comprises first and second axially extending conductors, each with at least one coiled segment defining an inductor, wherein the first and second conductors are connected in parallel to a capacitor at a distal portion of the lead.
10 . An MRI compatible lead according to claim 1 , wherein the at least one conductor coiled segment that defines the inductor is in series with a first electrode residing at a distal portion of the lead.
11 . An MRI compatible lead according to claim 1 , wherein the at least one electrode is configured to transmit therapeutic energy to local tissue.
12 . An MRI compatible lead according to claim 1 , wherein the conductors are about 25 cm long.
13 . An MRI compatible lead according to claim 1 , wherein the frequency dependent circuit comprises about a 500 pF capacitor in parallel with the inductor at a distal portion of the lead.
14 . An MRI compatible lead, comprising:
at least one elongate conductor;
at least one electrode in electrical communication with a distal portion of the at least one conductor; and
at least one RF filter in communication with the at least one conductor, the at least one RF filter comprising a frequency dependent circuit residing at a distal portion of the lead upstream of the at least one electrode,
wherein the RF filters configured to: (a) have a high impedance at an MRI scanner operating frequency in the MHz frequency range to thereby inhibit unwanted tissue heating from the at least one electrode when in an MRI system and; (b) to allow at least one of (i) energy in the KHz range to be delivered along the at least one conductor to the at least one electrode and (ii) the at least one electrode to detect electrophysiology signals at low frequency and transmit the detected signals along the conductor.
15 . An MRI compatible lead according to claim 14 , wherein the frequency dependent circuit comprises an inductor defined by a coiled conductor segment of the at least one conductor, wherein the coiled segment inductor resides upstream of the at least one electrode.
16 . A medical lead, comprising:
at least one conductor having opposing distal and proximal end portions;
at least one electrode in communication with the distal end portion of the at least one conductor; and
an RF filter having a resonant circuit operatively connected to the at least one conductor upstream of the at least one electrode, wherein the resonant circuit is substantially tuned to an RF excitation signal frequency of an MRI scanner to thereby generate a high impedance at an operating frequency of the MRI scanner.
17 . A lead according to claim 16 , wherein the resonant circuit comprises a shielded LC circuit, and wherein the conductor comprises an inductor in parallel with a capacitor.
18 . A lead according to claim 17 , wherein the inductor comprises a coiled segment of the conductor.
19 . A lead according to claim 18 , wherein the at least one conductor is a plurality of insulated conductors, each in communication with at least one of the at least one electrode.
20 . A lead according to claim 19 , wherein the resonant circuit is configured to allow low frequency therapeutic energy to be transmitted from the electrode.