Implantable electroacupuncture system for treating cardiovascular disease
An Implantable ElectroAcupuncture Device (IEAD) treats cardiovascular disease through application of stimulation pulses applied at at least one of acupoints EX-HN1, BL14, HT7, HT5, PC6, ST36, LI11, LU7, and LU2. The IEAD comprises an implantable, coin-sized, self-contained, leadless electroacupuncture device having at least two electrodes attached to an outside surface of its housing. The device generates stimulation pulses in accordance with a specified stimulation regimen. Power management circuitry within the device allows a primary battery, having a high internal impedance, to be used to power the device. The stimulation regimen generates stimulation pulses during a stimulation session of duration T 3 minutes applied every T 4 minutes. The duty cycle, or ratio T 3 /T 4 is very low, no greater than 0.05. The low duty cycle and careful power management allow the IEAD to perform its intended function for several years.
1. An Implantable ElectroAcupuncture System (IEAS) for treating cardiovascular disease through application of electroacupuncture (EA) stimulation pulses configured to be applied at a specified tissue location of a patient, comprising:
a leadless implantable electroacupuncture (EA) device comprising
a hermetically-sealed housing containing a primary power source, pulse generation circuitry powered by the primary power source, and a sensor that wirelessly senses operating commands generated external to the housing, wherein the pulse generation circuitry generates stimulation pulses in accordance with a specified stimulation regimen as controlled at least in part by the operating commands sensed through the sensor;
a plurality of electrodes located on an outside surface of the housing of the leadless EA device, the plurality of electrodes comprising a central electrode of a first polarity and centrally located on the outside surface of the housing of the leadless EA device and an annular electrode of a second polarity and that is spaced apart from and surrounds the central electrode on the outside surface of the housing of the leadless EA device, the plurality of electrodes electrically coupled to the pulse generation circuitry through at least one feed-through terminal passing through a wall of the housing, wherein the stimulation pulses are configured to be applied at the specified tissue location through the central electrode and the annular electrode in accordance with the specified stimulation regimen;
wherein the specified stimulation regimen defines how often a stimulation session comprising a stream of the stimulation pulses is applied to the patient, the specified stimulation regimen requiring that the stimulation session have a duration of T 3 minutes and a rate of occurrence of once every T 4 minutes, wherein the ratio of T 3 /T 4 is no greater than 0.05.
2. The IEAS of claim 1 wherein the plurality of electrodes are located on a bottom surface of the housing of the leadless EA device.
3. The IEAS of claim 1 wherein the dimensions of the leadless EA device are L×W×H, where L is the longest linear dimension, W is the shortest linear dimension measured in substantially the same plane as L, and H is the maximum height or thickness of the housing measured in a plane orthogonal with the plane where L and W are measured, and wherein L is no greater than about 25 mm, W is no less than about 15 mm and H is no greater than about 3 mm.
4. The IEAS of claim 1 wherein the primary power source of the leadless EA device comprises a battery having a nominal output voltage of no more than 3.0 volts and an internal impedance of no less than about 5 ohms.
5. The IEAS of claim 4 wherein the pulse generation circuitry includes:
a boost converter circuit that boosts the nominal output voltage of the battery to an output voltage VOUT that is at least three times the nominal output voltage;
a control circuit that selectively turns the boost converter circuit OFF and ON to limit an amount of current that may be drawn from the battery; and
an output circuit powered by VOUT and controlled by the control circuit that generates the stimulation pulses as defined by the specified stimulation regimen.
6. The IEAS of claim 5 wherein the stimulation pulses generated by the pulse generation circuit and delivered through the plurality of electrodes comprise voltage pulses having a voltage amplitude of no less than about 1 V and no greater than about 15 V.
7. The IEAS of claim 5 wherein the stimulation pulses generated by the pulse generation circuit and delivered through the plurality of electrodes comprise current pulses having a current amplitude of no less than about 1 milliampere (mA) and no greater than about 15 mA.
8. The IEAS of claim 7 wherein the battery has sufficient capacity to power the pulse generation circuitry in accordance with the specified stimulation regimen for a minimum of 2 years.
9. The IEAS of claim 1 wherein the duration of the stimulation session T 3 varies between 10 minutes and 60 minutes if the rate of occurrence of the stimulation session T 4 is set to a value between 1,200 minutes and 20,160 minutes [14 days]; and wherein T 3 varies between 10 minutes and a maximum T3 value, T 3 (max) if T 4 is set to a value between 720 minutes and 1,200 minutes, wherein the value of T 3 (max) varies as a function of T 4 as defined by the equation:
T 3(max)=0.05* T 4.
10. The IEAS of claim 1 further including an external control device adapted to selectively generate operating commands that are sensed by the sensor within the leadless EA device.
11. The IEAS of claim 10 wherein the sensor within the leadless EA device comprises a magnetic field sensor, and where the external control device comprises a magnet.
12. The IEAS of claim 1 , wherein the cardiovascular disease comprises at least one of heart failure, coronary artery disease, myocardial ischemia, and angina.
13. The IEAS of claim 1 , wherein the leadless EA device is configured to be implanted below a skin surface of the patient at or near an acupoint selected from the group of acupoints that includes: PC6, ST36, BL14, EX-HN1, HT7, HT5, LI11, LU2 and LU7.
14. The IEAS of claim 1 , wherein the specified tissue is a median nerve of the patient.
15. The IEAS of claim 1 , wherein the annular electrode is a ring electrode located around a circumferential edge of the housing.
16. The IEAS of claim 1 , wherein the housing is coin-sized and coin-shaped.
17. The IEAS of claim 1 , wherein the first polarity is an anodic polarity and the second polarity is a cathodic polarity.
18. The IEAS of claim 1 , wherein the first polarity is a cathodic polarity and the first polarity is an anodic polarity.
19. The IEAS of claim 1 , wherein the annular electrode comprises a plurality of electrode segments each having the second polarity and spaced apart from each other in a circumferential pattern around the central electrode.