MRI COMPATIBLE IMPLANTED ELECTRONIC MEDICAL DEVICE AND LEAD

• US 20080033497A1
• Filed: 08/24/2007
• Published: 02/07/2008
• Est. Priority Date: 11/04/2005
• Status: Active Grant

• Current Assignee: Kenergy, Inc.
• Original Assignee: Kenergy, Inc.
• Inventors: Denker, Stephen, Bulkes, Cherik
• Granted Patent: US 7,917,213 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents

Abstract

An implantable biocompatible lead that is also compatible with a magnetic resonance imaging scanner for the purpose of diagnostic quality imaging is described. The implantable electrical lead comprises a plurality of coiled insulated conducting wires wound in a first direction forming a first structure of an outer layer of conductors of a first total length with a first number of turns per unit length and a plurality of coiled insulated conducting wires wound in a second direction forming a second structure of an inner layer of conductors of a second total length with a second number of turns per unit length. The first and the second structures are separated by a distance with a layer of dielectric material. The distance and dielectric material are chosen based on the field strength of the MRI scanner. The lead may further comprise a conducting layer formed by coating a material consisting of medium conducting particles in physical contact with each other and a mechanically flexible, biocompatible layer forming an external layer of lead and in contact with body tissue or body fluids.

Claims

1. An implantable electrical lead that is biocompatible upon implantation in an animal and compatible with a magnetic resonance imaging scanner for the purpose of diagnostic quality imaging, said implantable electrical lead comprising:

a first plurality of coiled insulated conducting wires wound in a first direction forming an outer layer of conductors having a first total length with a first number of turns per unit of length;

a second plurality of coiled insulated conducting wires wound in a second direction forming an inner layer of conductors having a second total length with a second number of turns per unit of length, wherein the inner layer and the outer layer are separated by a distance with a layer of dielectric material wherein the distance and dielectric material are chosen based on a Larmor frequency of the magnetic resonance imaging scanner;

an electrically conductive layer having a conductivity between 0.001 and 200 Siemens per meter and comprising a material that has particles in physical contact with each other; and

a mechanically flexible, biocompatible layer forming an external layer of the implantable electrical lead and adapted to contact with body tissue or body fluids of an animal.

2. The implantable electrical lead as recited in claim 1 wherein the electrically conductive layer and the mechanically flexible, biocompatible layer are formed as a single layer.

3. The implantable electrical lead as recited in claim 1 wherein the electrically conductive layer is formed on the outer layer of conductors.

4. The implantable electrical lead as recited in claim 1 wherein the electrically conductive layer is formed on the inner layer of conductors.

5. The implantable electrical lead as recited in claim 1 wherein the implantable electrical lead is part of an electrical stimulation system.

6. The implantable electrical lead as recited in claim 5 wherein the implantable electrical lead is part of a cardiac pacing system.

7. The implantable electrical lead as recited in claim 5 wherein the implantable electrical lead is part of a cardiac defibrillation system.

8. The implantable electrical lead as recited in claim 1 wherein the first direction in which the first plurality of coiled insulated conducting wires are wound is different than the second direction in which the second plurality of coiled insulated conducting wires are wound.

9. The implantable electrical lead as recited in claim 1 wherein the first direction in which the first plurality of coiled insulated conducting wires are wound is the same as the second direction in which the second plurality of coiled insulated conducting wires are wound.

10. An implantable stimulation lead compatible in a magnetic resonance imaging (MRI) scanner for the purpose of diagnostic quality imaging, said implantable stimulation lead comprising:

a first plurality of insulated conducting wires wound in a first direction around a central axis to form an inner layer of electrical conductors of the lead;

a second plurality of insulated conducting wires wound in a second direction around the central axis and over the first plurality of insulated conducting wires, thereby forming an outer layer of conductors of the lead, wherein at least two wires of the second plurality of insulated conducting wires each have a section of a non-insulated conductor projecting outwardly from the lead to form electrodes; and

a conducting layer formed by a coating on one of the inner layer of conductors and the outer layer of conductors, wherein the coating has a conductivity between 0.001 and 200 Siemens per meter and comprises a material having particles in physical contact with each other.

11. The implantable stimulation lead as recited in claim 10 wherein each of the first and second plurality of insulated conducting wires having a proximal end connected to a parallel resonant circuit which blocks currents induced in the implantable stimulation lead by the magnetic resonance imaging scanner.

12. The implantable stimulation lead as recited in claim 10 wherein each section of a non-insulated conductor terminates at a component formed of an MRI compatible material for anchoring the section into tissue of an animal.

13. The implantable stimulation lead as recited in claim 10 wherein the outer layer of conductors is part of a cardiac defibrillation system and the inner layer of conductors is part of a cardiac pacing system.

14. An implantable biocompatible electrical lead that also is compatible with a magnetic resonance imaging scanner for the purpose of diagnostic quality imaging, said implantable biocompatible electrical lead comprising:

a first plurality of coiled insulated electrical conductors wound in a first direction forming an inner layer of conductors; and

a second plurality of coiled insulated electrical conductors wound in a second direction forming an outer layer of conductors;

wherein a number of turns of the inner and outer layers of electrical conductors per unit of length of the implantable biocompatible electrical lead, the distance between the inner and outer layers, a dielectric material between the inner and outer layers, and a total length of the implantable biocompatible electrical lead are chosen based on strength and frequency of an electromagnetic field produced by the magnetic resonance imaging scanner.

15. The implantable biocompatible electrical lead as recited in claim 14 further comprising:

an electrically conductive layer having a conductivity between 0.001 and 200 Siemens per meter and comprising a coating that has particles in physical contact with each other; and

a mechanically flexible, biocompatible layer forming an external layer of the implantable electrical lead that is adapted to contact tissue or body fluids of an animal.

16. The implantable biocompatible electrical lead as recited in claim 15 wherein the electrically conductive layer is also the mechanically flexible, biocompatible layer.

17. The implantable biocompatible electrical lead as recited in claim 15 wherein the conductive layer is formed on the outer layer of conductors.

18. The implantable biocompatible electrical lead as recited in claim 15 wherein the conductive layer is formed on the inner layer of conductors.

19. The implantable biocompatible electrical lead as recited in claim 15 wherein the lead is part of an electrical stimulation system.

20. The implantable biocompatible electrical lead as recited in claim 19 wherein the lead is part of an organ stimulation system, wherein the organ is one of heart, brain, ear, stomach, prostate, urinary bladder, pancreas, liver, and spine.

21. The implantable biocompatible electrical lead as recited in claim 19 wherein the implantable biocompatible electrical lead is part of a cardiac defibrillation system.

22. The implantable biocompatible electrical lead as recited in claim 14 wherein the implantable biocompatible electrical lead is part of an electrical sensing system.

23. The implantable biocompatible electrical lead as recited in claim 22 wherein the implantable biocompatible electrical lead is part of an electrical stimulation system.

24. The implantable biocompatible electrical lead as recited in claim 14 wherein the first direction and the second direction are the same.

25. The implantable biocompatible electrical lead as recited in claim 14 wherein the first direction and the second direction are different.

26. The implantable biocompatible electrical lead as recited in claim 14 wherein each of the first and second plurality of coiled insulated electrical conductors has a portion without insulation that is adapted to be exposed to body tissue or body fluids upon implantation in an animal, wherein the portion has a length that is less than a quarter wavelength in the body tissue at the frequency of an electromagnetic field produced by the magnetic resonance imaging scanner.