Electrode Configuration for an Implantable Electroacupuncture Device

• US 20140214144A1
• Filed: 02/25/2013
• Published: 07/31/2014
• Est. Priority Date: 03/06/2012
• Status: Active Grant

• Current Assignee: Valencia Bioscience, Inc.
• Original Assignee: Valencia Technologies Corporation
• Inventors: Peterson, David K. L., Thenuwara, Chuladatta H.
• Granted Patent: US 9,066,845 B2
• Time in Patent Office: Days
• US Class Current: 607/116
• CPC Class Codes: A61H 2201/5005 for controlling frequency distribution, modulation or interference of a driving signal
• CPC Class Codes: A61H 2201/5035 Several programs selectable
• CPC Class Codes: A61H 2201/5038 freely programmable by the user
• CPC Class Codes: A61H 2201/5097 wireless
• CPC Class Codes: A61H 39/002 Using electric currents electrotherapy A61N1/32
• CPC Class Codes: A61N 1/04 Electrodes electrosurgical electrodes A61B18/14
• CPC Class Codes: A61N 1/0504 Subcutaneous electrodes
• CPC Class Codes: A61N 1/36117 for treating hypertension
• CPC Class Codes: A61N 1/36125 Details of circuitry or electric components
• CPC Class Codes: A61N 1/3616 Voltage density or current density
• CPC Class Codes: A61N 1/36175 Pulse width or duty cycle
• CPC Class Codes: A61N 1/37205 Microstimulators, e.g. implantable through a cannula
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: A61N 1/3758 Packaging of the components within the casing
• CPC Class Codes: A61N 1/3782 producing a voltage above the power source level

Abstract

An implantable electroacupuncture device (IEAD) treats a disease or medical condition of a patient through application of stimulation pulses applied at a specified acupoint or other target tissue location at a very low duty cycle. In a preferred implementation, the IEAD is an implantable, coin-sized, self-contained, leadless device having at least two electrodes attached to an outside surface of its housing, with at least one electrode on the top or bottom surface of the housing functioning as a cathode, and at least one electrode on the perimeter edge of the housing functioning as an anode. The electrodes may be segmented to include an array of smaller cathodic or anodic electrodes, each of which may be selectively turned ON or OFF so as to provide a convenient mechanism for adjusting the density of the stimulus current flowing through the cathodic electrode surface area.

Claims

1. An implantable electroacupuncture device (IEAD) for treating a specified medical condition of a patient through application of electroacupuncture (EA) stimulation pulses applied substantially at or near a specified acupoint, comprising:

a housing having a thickness of no greater than about 2.5 mm;

at least one cathodic electrode and at least one anodic electrode formed as an integral part of the housing;

stimulation circuitry residing inside the housing and electrically coupled to the at least one cathodic and at least one anodic electrodes, wherein the stimulation circuitry generates EA stimulation pulses that are delivered to body tissue through the at least one cathodic and at least one anodic electrodes in accordance with a prescribed stimulation regimen, wherein said stimulation regimen defines the duration and rate at which a stimulation session is applied to the patient, said stimulation regimen requiring that the stimulation session have a duration of T3 minutes and a rate of occurrence of once every T4 minutes, wherein the ratio of T3/T4 is no greater than 0.05, and wherein during each stimulation session EA stimulation pulses having one or more specified widths and amplitudes are generated at one or more specified rates; and

a coin-cell type primary battery residing inside the housing that provides the operating power for the stimulation circuitry, wherein the primary battery has an internal impedance that is greater than 5 ohms;

wherein the at least one cathodic electrode is located on a top or bottom surface of the housing and positioned no closer than 5 mm from the closest edge of the nearest at least one anodic electrode, and wherein the total surface area of the at least one cathodic electrode is no smaller than about 0.5 mm², and wherein the positioning and surface area of the at least one cathodic electrode is optimally selected to allow a desired current density to flow through the electrode surface area without causing electrode corrosion or current shunting.

2. The IEAD of claim 1, wherein the at least one cathodic electrode comprises a first cathodic electrode located on a top surface of the housing and a second cathodic electrode located on a bottom surface of the housing, and wherein the stimulation circuitry includes switching circuitry that selectively activates (i) only the first cathodic electrode, or (ii) only the second cathodic electrode, or (iii) both the first and second cathodic electrodes when the stimulation pulses are delivered to the body tissue in accordance with the prescribed stimulation regimen.

3. The IEAD of claim 2, wherein the at least one anodic electrode is formed as a ring electrode residing substantially around a perimeter edge of the housing.

4. The IEAD of claim 3, wherein the first and second cathodic electrodes each comprise multiple small cathodic electrodes distributed over the top and bottom surface areas of the housing in accordance with a prescribed pattern.

5. The IEAD of claim 4 wherein the at least one anodic electrode comprises multiple small anodic electrodes distributed around the perimeter edge of the housing.

6. The IEAD of claim 5 wherein the stimulation circuitry includes additional cathodic switching circuitry that selectively activates only a desired grouping of the first and second cathodic electrodes, wherein the location of the body tissue receiving the stimulation pulses may be selected by controlling which groups of electrodes are activated and which are not activated, wherein an activated electrode comprises an electrode that is turned ON by the switching circuitry so that an electrical current may flow through the electrode, and a non-activated electrode comprises an electrode that is turned OFF by the switching circuitry so as to prevent electrical current from flowing through the electrode.

7. The IEAD of claim 1 wherein the housing has a maximum linear dimension no greater than about 25 mm in a first plane orthogonal to a second plane wherein the thickness of the housing is measured, and wherein the at least one cathodic electrode comprises a single cathodic electrode located in the center of a bottom surface of the housing, the bottom surface comprising that surface of the housing adapted to face towards a desired target tissue location whereat EA stimulation pulses are to be applied.

8. The IEAD of claim 1 wherein the single cathodic electrode is segmented into a central electrode and a plurality of concentric ring electrodes surrounding the central electrode.

9. An implantable electroacupuncture (EA) device adapted to be implanted at a specified acupoint of a patient, the electroacupuncture device including:

a disc-shaped housing having a top surface, a bottom surface, and a perimeter edge connecting the top surface to the bottom surface;

at least one cathodic electrode and at least one anodic electrode formed to reside on, or comprise an integral part of, the surfaces of the housing, wherein the at least one cathodic electrode is on the top or bottom surface of the housing, and the at least one anodic electrode is on the perimeter edge surface of the housing;

stimulation circuitry residing inside the housing and electrically coupled to the at least one cathodic electrode and the at least one anodic electrode, wherein the stimulation circuitry generates stimulation pulses of electrical current that are delivered to body tissue surrounding the housing through the at least one cathodic electrode and the at least one anodic electrode in accordance with a prescribed stimulation regimen;

wherein the at least one cathodic electrode is configured from a prescribed electrode material having a surface area sufficiently large to allow a desired current density to flow through it without causing electrode corrosion, and further

wherein the at least one cathodic electrode is positioned sufficiently far from the at least one anodic electrode so as to prevent current shunting to occur between the at least one cathodic electrode and the at least one anodic electrode before the stimulation pulses of electrical current have penetrated into the body tissue a specified distance.

10. The EA device of claim 9, wherein the cathodic electrode comprises a first cathodic electrode located on the top surface of the housing and a second cathodic electrode located on the bottom surface of the housing, and wherein the stimulation circuitry residing inside of the housing includes switching circuitry that selectively activates (i) only the first cathodic electrode, or (ii) only the second cathodic electrode, or (iii) both the first and second cathodic electrodes when the stimulation pulses are delivered to the body tissue in accordance with the prescribed stimulation regimen.

11. The EA device of claim 10, wherein the first and second cathodic electrodes each comprise multiple small cathodic electrodes distributed over the top and bottom surface areas of the housing in accordance with a prescribed pattern.

12. The EA device of claim 11 wherein the at least one anodic electrode comprises multiple small anodic electrodes distributed around the perimeter edge of the housing.

13. The EA device of claim 11 wherein the stimulation circuitry includes additional cathodic switching circuitry that selectively energizes only a desired grouping of the first and second cathodic electrodes, wherein the location of the body tissue receiving the stimulation pulses may be selected by controlling which groups of electrodes are energized and which are not energized, wherein an energized electrode comprises an electrode that is turned ON by the switching circuitry so that an electrical current may flow through the electrode, and a non-energized electrode comprises an electrode that is turned OFF by the switching circuitry so as to prevent electrical current from flowing through the electrode.

14. The EA device of claim 9 wherein the at least one cathodic electrode comprises a single cathodic electrode located in the center of a bottom surface of the housing, the bottom surface comprising that surface of the housing adapted to face towards a target tissue location below the specified acupoint on the skin surface of the patient.

15. The EA device of claim 14 wherein the stimulation circuitry generates monophasic stimulation pulses having a magnitude of between 2 to 25 ma, a pulse width of between 100 to 600 msec, and a frequency of between 1 and 5 Hz.

16. The EA device of claim 15 wherein the housing has a diameter of no greater than 25 mm, a thickness no greater than 3 mm, and is adapted to be implanted at acupoint P6 at a tissue depth of between 3-6 mm.

17. The EA device of claim 16 wherein the stimulation regimen provides a stimulation session during which stimulation pulses are continuously generated, wherein the stimulation session has a duration of between 10 and 60 minutes, and further wherein, after an initialization period of no longer than two weeks, the stimulation session is applied to the patient no more than twice a week and no less than once every other week.

18. A method of operating an implantable electroacupuncture (EA) device, the EA device having a thickness of no greater than 2.5 mm, and at least two electrodes carried on or formed as an integral part of the housing;

and further wherein stimulation circuitry resides within the housing and is coupled to the at least two electrodes, and wherein the stimulation circuitry generates stimulation pulses that are applied to the at least two electrodes in accordance with a prescribed stimulation regimen, wherein the method of operating comprises;

configuring one of the at least two electrodes as a cathodic electrode, and locating the cathodic electrode so as to reside on the top or bottom surface of the coin-sized and -shaped housing;

configuring the other one of the at least two electrodes as an anodic electrode, and locating the anodic electrode so as to reside on a perimeter edge of the coin-sized and -shaped housing; and

applying monophasic stimulation to the anodic and cathodic electrodes during a stimulation session that lasts T3 minutes at a rate of once every T4 minutes, during which stimulation session monophasic stimulation pulses having a pulse width of T1 msec are applied through the cathodic and anodic electrodes at a rate of once every T2 msec;

wherein T1 has a value of between 0.1 and 0.6 msec, T2 has a value of between 200 and 1000 msec, T3 has a value of between 10 and 60 minutes, and the ratio of T3/T4 is no greater than 0.05.

19. The method of claim 18 further comprising:

configuring the size of the at least two electrodes to provide a maximum current density without causing electrode corrosion; and

spacing the distance between the cathodic and anodic electrodes to minimize the likelihood of current shunting.

20. The method of claim 19 wherein configuring the size of the at least two electrodes comprises making the surface area of the electrodes to be no less than 3.14 mm² when the electrodes are made from stainless steel, and no less than 0.5 mm2 when the electrodes are made from platinum, and wherein spacing the distance between the cathodic and anodic electrodes comprises making the minimum distance between a cathodic electrode and an anodic electrode to be at least 5 mm.