Method for treating cardiovascular disease using implantable electroacupuncture device
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 T3 minutes applied every T4 minutes. The duty cycle, or ratio T3/T4 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. A method of treating heart failure, coronary artery disease, myocardial ischemia or angina in a patient using a leadless implantable electroacupuncture device (IEAD) that includes a central electrode of a first polarity and centrally located on an outside surface of a housing of the leadless IEAD 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 IEAD, said method comprising:
(a) implanting the leadless IEAD below a skin surface of the patient at or near an acupoint selected from a group of acupoints that includes: PC6, ST36, BL14, EX-HN1, HT7, HT5, LI11, LU2 and LU7, and
(b) enabling the leadless IEAD to apply stimulation sessions at the acupoint by way of the central electrode and the annular electrode in accordance with a stimulation regimen, wherein the stimulation sessions each comprise a plurality of stimulation pulses, wherein the stimulation regimen defines the stimulation sessions to each have a duration of T3 minutes and a rate of occurrence of once every T4 minutes, wherein a ratio of T3 to T4 is no greater than 0.05, and wherein T3 is at least 10 minutes and no greater than 60 minutes.
2. The method of claim 1 further including setting the stimulation pulses to have a duration of T1 seconds and to occur at a rate of once every T2 seconds, wherein T1 is 0.1 to 2.0 milliseconds, and T2 is 200 to 1000 milliseconds.
3. The method of claim 1 wherein the leadless IEAD further includes a magnetic field sensor for sensing a presence or absence of an external magnetic field, and wherein the enabling the leadless IEAD to provide EA stimulation pulses in accordance with the specified stimulation regimen comprises selectively placing and removing a magnetic field external to the leadless IEAD in a prescribed turn-on sequence that is recognized and acted upon by the electronic circuitry as an enabling command for initializing the specified stimulation regimen.
4. The method of claim 3 wherein the prescribed turn-on sequence comprises:
(i) sensing an absence of the external magnetic field; then
(ii) sensing a presence of the external magnetic field for 10 seconds; then
(iii) sensing a continued presence of the external magnetic field for an additional plurality of 5 second intervals, during which an amplitude of a stimulus pulse increases every 5 seconds starting at zero amplitude and ending when a comfortable stimulus amplitude has been reached; then
(iv) removing the external magnetic field to set the amplitude at the comfortable stimulus amplitude, whereupon the stimulation session begins and continues for T3 minutes, after which a time interval, TI, begins that defines the time interval between stimulus sessions, after which interval a next stimulation session begins and continues for T3 minutes, after which the time interval TI begins again, and this sequence of stimulus sessions of duration T3 seconds followed by an interval of TI continues over and over again regardless of whether an external magnetic field is present or not.
5. The method of claim 1 wherein the housing comprises a thin, coin-sized and coin-shaped housing, and wherein the annular electrode comprises a ring electrode that is placed around a circumferential edge of the coin-sized and coin-shaped housing.
6. The method of claim 1 , further comprising powering the leadless IEAD by a disc battery having a specified nominal output voltage of about 3 volts and an internal impedance of at least 5 ohms.
7. The method of claim 6 , including controlling the electronic circuitry within the leadless IEAD to limit an instantaneous current drawn from the primary battery so that an output voltage of the primary battery does not drop more than about 11% below an output voltage of the primary battery when current is being drawn from the primary battery, where the output voltage of the primary battery is equal to the specified nominal output voltage of the primary battery less a voltage drop caused by the instantaneous current flowing through the internal impedance of the primary battery.
8. The method of claim 7 wherein the electronic circuitry within the leadless IEAD includes a boost converter circuit, and wherein the controlling the electronic circuitry within the leadless IEAD to limit the instantaneous current drawn from the battery comprises modulating an operation of the boost converter circuit between an ON state and an OFF state.
9. The method of claim 6 , wherein the enabling of the leadless IEAD to apply the stimulation sessions comprises using electronic circuitry within the leadless IEAD to generate the stimulation sessions.
10. The method 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.