Apparatus and process for reducing the susceptability of active implantable medical devices to medical procedures such as magnetic resonance imaging

A feedthrough terminal assembly for an active implantable medical device (AIMD), comprising:

• a plurality of leadwires extending from electronic circuitry of the AIMD;
• a lossy ferrite inductor through which the leadwires extend in non-conductive relation for increasing the impedence 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;
• and
• one or more additional lossy ferrite inductors through which the leadwires extend in non-conductive relation, wherein the lossy ferrite inductors are disposed adjacent to one another, and wherein the lossy ferrite inductors are each comprised of materials having different physical or electrical properties.

A feedthrough terminal assembly for an active implantable medical device (AIMD), comprising:

• a plurality of leadwires extending from electronic circuitry of the AIMD;
• a lossy ferrite inductor through which the leadwires extend in non-conductive relation for increasing the impedence 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;
• and
• a cancellation antenna extending through the lossy ferrite inductor in non-conductive relation.

A feedthrough terminal assembly for an active implantable medical device (AIMD), comprising:

• a plurality of leadwires extending from electronic circuitry of the AIMD;
• a lossy ferrite inductor through which the leadwires extend in non-conductive relation for increasing the impedence 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 feedthrough filter capacitor having a first set of electrode plates conductively coupled to at least one of the leadwires, and a second set of electrode plates conductively coupled to a housing, ferrule or ground plane of the active implantable medical device;
• and
• a second lossy ferrite inductor through which the leadwires extend in non-conductive relation, wherein the lossy ferrite inductors are disposed on opposite sides of the capacitor.

A feedthrough terminal assembly for an active implantable medical device (AIMD), comprising:

• a plurality of leadwires extending from electronic circuitry of the AIMD;
• a lossy ferrite inductor through which the leadwires extend in non-conductive relation for increasing the impedence 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;
• and
• a feedthrough filter capacitor having a first set of electrode plates conductively coupled to at least one of the leadwires, and a second set of electrode plates conductively coupled to a housing, ferrule or ground plane of the active implantable medical device, wherein the capacitor is disposed on a body fluid side of the feedthrough terminal assembly.

A process for filtering electromagnetic interference (EMI) in a plurality of leadwires extending from an active implantable medical device (AIMD) to different points within a human body, comprising the steps of:

• passing the leadwires through a common inductive element to increase the impedence of the leadwires at selected RF frequencies and reduce magnetic flux core saturation of the inductive element through phase cancellation of signals carried by the leadwires;
• passing the leadwires through one or more additional inductive elements;
• and
• disposing the inductive elements adjacent to one another;
• wherein the inductive elements are each comprised of materials having different physical or electrical properties.

A process for filtering electromagnetic interference (EMI) in a plurality of leadwires extending from an active implantable medical device (AIMD) to different points within a human body, comprising the steps of:

• passing the leadwires through a common inductive element to increase the impedence of the leadwires at selected RF frequencies and reduce magnetic flux core saturation of the inductive element through phase cancellation of signals carried by the leadwires;
• conductively coupling at least one of the leadwires to a first set of electrode plates of a feedthrough capacitor, and conductively coupling a second set of electrode plates of the feedthrough capacitor to a housing, ferrule or ground plane of the active implantable medical device;
• passing the leadwires through a second inductive element in non-conductive relation;
• and
• disposing the inductive elements on opposite sides of the capacitor.

A process for filtering electromagnetic interference (EMI) in a plurality of leadwires extending from an active implantable medical device (AIMD) to different points within a human body, comprising the steps of:

• passing the leadwires through a common inductive element to increase the impedence of the leadwires at selected RF frequencies and reduce magnetic flux core saturation of the inductive element through phase cancellation of signals carried by the leadwires;
• conductively coupling at least one of the leadwires to a first set of electrode plates of a feedthrough capacitor, and conductively coupling a second set of electrode plates of the feedthrough capacitor to a housing, ferrule or ground plane of the active implantable medical device;
• and
• associating a second feedthrough capacitor with the inductive element.