Subcutaneous spiral electrode for sensing electrical signals of the heart

• US 6,512,940 B1
• Filed: 10/31/2000
• Issued: 01/28/2003
• Est. Priority Date: 10/31/2000
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Strom, James, Brabec, Scott J., Brennen, Kenneth R., Schindeldecker, William
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US09/703,152
• Time in Patent Office: 819 Days
• Field of Search: 600/372, 600/373, 600/374, 600/375, 600/376, 600/377, 600/509
• US Class Current: 600/374
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence

Abstract

An implantable pacemaker is provided with subcutaneous spiral electrodes for sensing electrical signals of the heart. Subcutaneous spirals or spiral electrodes are embedded individually into three or four recessed casings placed in a compliant surround that is attached to the perimeter of the implanted medical device. The electrodes are electrically connected to the circuitry of the implanted pacemaker and detect cardiac depolarization waveforms displayable as electrocardiographic tracings on an external instrument such as a programmer. The spiral electrode constitutes the proximal end of a continuous wire that upon egress from the recessed casing is insulated using insulative material.

Claims

1. An implantable electrocardiographic data collection system for recording electrocardiographic data, the system comprising:

a hermetically sealed case;

a plurality of subcutaneous spiral electrodes forming an array, mounted in a recessed casing formed about a periphery surface of the case; and

signal processing circuitry inside the case coupled to the electrodes via a connector feedthrough assembly in contact with amplifiers in a microprocessor circuitry.

2. The system of claim 1 wherein said recessed casing is composed of a polymer.

3. The system of claim 2 wherein the case includes walls into which body fluid is allowed to flow so that the body fluid is above and around the spiral electrodes and is contained in the casing by a small circumferential well constructed into the base of said recessed casing.

4. The system according to claim 3 wherein the spiral electrodes include spiral coils consisting of materials selected from the group of platinum, platinum alloys and platinum group of metals with or without alloy components.

5. The system according to claim 3 wherein said spiral electrodes include a spiral coil forming a proximal end of a continuous wire that upon egress from said recessed casing, is insulated by tubular insulative materials.

6. The system according to claim 5 wherein said insulated tubular insulative material feeds into channels located on the inner arc on a compliant surround.

7. The system according to claim 5 wherein a distal end of said continuous wire is welded to connector feedthrough assembly in contact with amplifiers in a microprocessor secretary.

8. Apparatus for leadless acquistion of electrocardiographic data using an array of subcutaneous spiral electrodes to detect cardiac depolarization signals that are very small, and signals with low slew rates, the system comprising:

a hermetically sealed case;

a plurality of spiral subcutaneous electrodes attached to a pulse generator by a compliant surround, mounted in the periphery surface of the case; and

signal processing circuitry inside the case and electrically coupled to the plurality of electrodes to detect cardiac signals and provide electrocardiographic data.

9. The apparatus of claim 8 wherein the surface of said plurality of spiral electrodes is isolated from direct contact with body tissue and moving body fluids.

10. The apparatus of claim 9 wherein said surface of said electrodes is treated with electrode coating such as platinum black or titanium nitride to enhance signal conducting and depolarization properties.

11. The apparatus of claim 9 wherein said plurality of said electrodes include a continuous wire connection without weld or bonds on the electrode surface.

12. The plurality of electrodes of claim 9 wherein said electrodes are anchored in the case, free of any chemical bonding, in a recessed section of the case.

13. The apparatus of claim 12 wherein a portion of said electrode that is covered by said recessed section is minimal to prevent potential excursions caused by fluid creep or by trapped oxygen or hydrogen gradient.

14. The apparatus of claim 9 wherein said electrodes include a coiled electrode design in a rectangular configuration.

15. The apparatus of claim 9, wherein the case includes a recessed section having a well, and wherein said electrodes include a flat plated electrode embedded within the well of said recessed section.

16. The apparatus of claim 15 wherein said flat plated electrode is stabilized against electromagnetic potential disturbances by structuring a bottom of the well of said recessed section patterned with a cross-hatch structure with elevations and depressions formed to have a minimum contact area between the plate and the polymer used in the recessed section.

17. The apparatus of claim 16 wherein said cross-hatch structure supports said electrode and enables fluid contact with the underside of said electrode surface.

18. Apparatus of claim 9 wherein a protective cap is placed to allow fluid to ingress to the active electric element wherein said protective cap is placed over the recessed section containing said flat electrode.

19. The apparatus of claim 18 wherein said cap is structured to apply pressure on said electrode for pressing against said cross-hatch structure of the recessed section to prevent motion of said electrode.

20. The apparatus of claim 19 wherein said cap is structured to dampen external fluid motion that might otherwise reach said electrode and cause electroconnectic transience.

21. The apparatus of claim 9 wherein said electrode surface is treated with a coating to protect from contamination during handling.

22. The apparatus of claim 21 wherein said coating includes dexamethasone sodium phosphates to provide protection to enhance the wetting of the electrode surface after implant.

23. The apparatus of claim 22 wherein conductive hydro gels are applied to said electrode surface to protect from damage during handling and prevent contamination.

24. The apparatus of claim 8 wherein a spacing of said electrodes around a compliant surround provides maximum electrode spacing.

25. The apparatus of claim 24 wherein said spacing maintains a maximum average signal using two equal vectors.

26. The apparatus of claim 25 wherein said spacing of said equal vectors includes a 90°

angle vector.