Patent Application
20180021566
High blood pressure (HBP), also known as hypertension, affects approximately one billion individuals world-wide. Hypertension is generally viewed as a bad thing if it persists for long periods of time or is extremely high over a very short (e.g., hours) period of time. The adverse effects of hypertension typically take many years to develop, but they include stroke, angina and heart attacks.
High blood pressure is traditionally treated with drugs. Unfortunately, not every patient who develops HBP responds favorably to such drugs. Many patients have severe adverse side effects. For others, the drugs are not effective for their intended purpose. Thus, there is a critical need for alternative methods and techniques for treating high blood pressure.
Alternate techniques for treating HBP include electrical stimulation. For example, several proposals have been made to treat moderately elevated blood pressure using highly invasive methods such as vagal (part of the vagus nerve) nerve stimulation, spinal cord stimulation and deep brain stimulation. It has been known in the past that one can stimulate the vagal nerves by invasively dissecting the major nerve bundle and placing a spiral or enveloping nerve-type cuff around the nerve bundle. The nerve fibers are then directly stimulated by an electrical field to achieve a reduction in epilepsy, heart-rate slowing, and potential blood pressure changes.
Currently, only nerve cuff-type electrodes or in-placement-type electrodes are used for nerve stimulation, other than in the spinal cord. These types of electrodes can potentially cause irreversible nerve damage due to swelling or direct mechanical damage of the nerve. The placement of these electrodes either around the nerve bundle or into the neural perineum also poses a significant risk. The electrode placement is usually performed through very invasive surgery which in and of itself produces a high risk to nerve damage.
U.S. Pat. No. 5,707,400, issued to Terry, entitled “Treating Refractory Hypertension By Nerve Stimulation,” proposes implantation of an electrical coil or cuff around the vagus nerve, which runs superficially through the neck, and stimulation of the vagus nerve to lower high blood pressure.
U.S. Pat. No. 6,522,926, issued to Kieval, entitled “Devices and Methods for Cardiovascular Reflex Control,” and several other patents issued to the same inventor, describe devices, systems and methods by which the blood pressure is reduced by activating baroreceptors. The baroreceptors are the biological sensors in the wall of the carotid artery that indicate to the brain an abrupt rise or fall of blood pressure by responding to the stretch of the arterial wall. In response to baroreceptor stimulation, the brain reduces the pumping of the heart with the consequential moderation of blood pressure. This phenomenon is known as the body's “baroreflex”.
U.S. Pat. No. 5,199,428, issued to Obel, entitled “Implantable Electrical Nerve Stimulator/Pacemaker with Ischemia for Decreasing Cardiac Workload,” describes a method and apparatus for (1) stimulating the right and/or left carotid sinus nerves, (2) the right stellate ganglion or (3) the epidural space of the spine with electrical pulses in response to detected myocardial ischemia to decrease cardiac workload as a method to protect the myocardium.
The methods described above are potent and are capable of, at least temporarily, reducing blood pressure in a patient. However, such methods are highly invasive and have potentially debilitating or life threatening side effects. In general, it may be said that these methods attempt to regulate blood pressure by directly changing the vital parts of the central nervous system such as brain, spinal cord, vagus nerve and carotid sinus nerves. The potential side effects of such a device,—including nerve damage and paralysis—make the use of these methods unlikely except in the most severe cases where the high risk can be justified.
Another alternative technique for treating HBP, and a host of other physiological conditions, illnesses and deficiencies is acupuncture. Acupuncture has been practiced in Eastern civilizations (principally China, but also other Asian countries) for over 2500 years. It is still practiced today throughout many parts of the world, including the United States and Europe. A good summary of the history of acupuncture, and its potential applications may be found in Cheung, et al., “The Mechanism of Acupuncture Therapy and Clinical Case Studies”, (Taylor & Francis, publisher) (2001) ISBN 0-415-27254-8, hereafter referred to as “Cheung, Mechanism of Acupuncture, 2001.” The Forward, Chapters 1-3, and 5 of Cheung, Mechanism of Acupuncture, 2001, is incorporated herein by reference.
Despite the practice in Eastern countries for over 2500 years, it was not until President Richard Nixon visited China (in 1972) that acupuncture began to be accepted in Western countries, such as the United States and Europe. One of the reporters who accompanied Nixon during his visit to China, James Reston, from the New York Times, received acupuncture in China for post-operative pain after undergoing an emergency appendectomy under standard anesthesia. Reston experienced pain relief from the acupuncture and wrote about it in The New York Times. In 1973 the American Internal Revenue Service allowed acupuncture to be deducted as a medical expense. Following Nixon's visit to China, and as immigrants began flowing from China to Western countries, the demand for acupuncture increased steadily. Today, acupuncture therapy is viewed by many as a viable alternative form of medical treatment, alongside Western therapies. Moreover, acupuncture treatment is now covered, at least in part, by most insurance carriers. Further, payment for acupuncture services consumes a not insignificant portion of healthcare expenditures in the U.S. and Europe. See, generally, Cheung, Mechanism of Acupuncture, 2001, vii.
Acupuncture is an alternative medicine that treats patients by insertion and manipulation of needles in the body at selected points. Novak, Patricia D. et al (1995). Dorland's Pocket Medical Dictionary (25th ed.). Philadelphia: (W. B. Saunders Publisher). ISBN 0-7216-5738-9. The locations where the acupuncture needles are inserted are referred to herein as “acupuncture points” or simply just “acupoints”. The location of acupoints in the human body has been developed over thousands of years of acupuncture practice, and maps showing the location of acupoints in the human body are readily available in acupuncture books or online. For example, see, “Acupuncture Points Map,” found online at: http://www.acupuncturehealing.org/acupuncture-points-map.html. Acupoints are typically identified by various letter/number combinations, e.g., L6, S37, which maps also identify what condition, illness or deficiency the particular acupoint affects when manipulation of needles inserted at the acupoint is undertaken.
References to the acupoints in the literature are not always consistent with respect to the format of the letter/number combination. Some acupoints are identified by a name only, e.g., Tongi. The same acupoint may be identified by others by the name followed with a letter/number combination placed in parenthesis, e.g., Tongi (HT5). The first letter typically refers to a body organ, or other tissue location associated with, or affected by, that acupoint. However, usually only the letter is used in referring to the acupoint, but not always. Thus, for example, the acupoint P-6 is the same as acupoint Pericardium 6, which is the same as PC-6, which is the same as PC6, which is the same as Pe 6 which is the same as Neiguan. For purposes of this patent application, unless specifically stated otherwise, all references to acupoints that use the same name, or the same first letter and the same number, and regardless of slight differences in second letters and formatting, are intended to refer to the same acupoint. Thus, for example, the acupoint Neiguan is the same acupoint as Neiguan (P6), which is the same acupoint as Neiguan (PC6), which is the same acupoint as Neiguan (PC-6), which is the same acupoint as Neiguan (Pe-6), which is the same acupoint as P6, or P 6, or PC-6, PC6 or Pe 6.
An excellent reference book that identifies all of the traditional acupoints within the human body is WHO STANDARD ACUPUNCTURE POINT LOCATIONS IN THE WESTERN PACIFIC REGION, published by the World Health Organization (WHO), Western Pacific Region, 2008 (updated and reprinted 2009), ISBN 978 92 9061 248 7 (hereafter “WHO Standard Acupuncture Point Locations 2008”). The Table of Contents, Forward (page v-vi) and General Guidelines for Acupuncture Point Locations (pages 1-21), as well as pages 45, 64, 151 and 154 (which pages illustrate with particularity the location of acupoints ST36, ST37, PC5 and PC6) of the WHO Standard Acupuncture Point Locations 2008 are submitted herewith as Appendix D, and are incorporated herein by reference.
While many in the scientific and medical community are highly critical of the historical roots upon which acupuncture has developed, (e.g., claiming that the existence of meridians, qi, yin and yang, and the like have no scientific basis), see, e.g., http://en.wikipedia.org/wiki/Acupuncture, few can refute the vast amount of successful clinical and other data, accumulated over centuries of acupuncture practice, that shows needle manipulation applied at certain acupoints is quite effective.
The World Health Organization (WHO) and the United States' National Institutes of Health (NIH) have stated that acupuncture can be effective in the treatment of neurological conditions and pain. Reports from the USA's National Center for Complementary and Alternative Medicine (NCCAM), the American Medical Association (AMA) and various USA government reports have studied and commented on the efficacy of acupuncture. There is general agreement that acupuncture is safe when administered by well-trained practitioners using sterile needles, but not on its efficacy as a medical procedure.
An early critic of acupuncture, Felix Mann, who was the author of the first comprehensive English language acupuncture textbook Acupuncture: The Ancient Chinese Art of Healing, stated that “The traditional acupuncture points are no more real than the black spots a drunkard sees in front of his eyes.” Mann compared the meridians to the meridians of longitude used in geography—an imaginary human construct. Mann, Felix (2000). Reinventing acupuncture: a new concept of ancient medicine. Oxford: Butterworth-Heinemann. pp. 14; 31. ISBN 0-7506-4857-0. Mann attempted to combine his medical knowledge with that of Chinese theory. In spite of his protestations about the theory, however, he apparently believed there must be something to it, because he was fascinated by it and trained many people in the west with the parts of it he borrowed. He also wrote many books on this subject. His legacy is that there is now a college in London and a system of needling that is known as “Medical Acupuncture”. Today this college trains doctors and western medical professionals only.
For purposes of this patent application, the arguments for and against acupuncture are interesting, but not that relevant. What is important is that a body of literature exists that identifies several acupoints within the human body that, rightly or wrongly, have been identified as having an influence on, or are otherwise somehow related to, the treatment of various physiological conditions, deficiencies or illnesses, including hypertension. With respect to these acupoints, the facts speak for themselves. Either these points do or do not affect the conditions, deficiencies or illnesses with which they have been linked. The problem lies in trying to ascertain what is fact from what is fiction. This problem is made more difficult when conducting research on this topic because the insertion of needles, and the manipulation of the needles once inserted, is more of an art than a science, and results from such research become highly subjective. What is needed is a much more regimented approach for doing acupuncture research.
It should also be noted that other medical research, not associated with acupuncture research, has over the years identified nerves and other locations throughout a patient's body where the application of electrical stimulation produces a beneficial effect for the patient. Indeed, the entire field of neurostimulation deals with identifying locations in the body where electrical stimulation can be applied in order to provide a therapeutic effect for a patient. For purposes of this patent application, such known locations within the body are treated essentially the same as acupoints—they provide a “target” location where electrical stimulation may be applied to achieve a beneficial result, whether that beneficial result is to reduce pain, to treat myocardial ischemia, to treat hypertension, to mitigate some other form of cardiovascular disease or to address some other issue associated with a disease or condition of the patient.
Returning to the discussion regarding acupuncture, some have proposed applying moderate electrical stimulation at selected acupuncture points through the needles that have been inserted. See, e.g., http://en.wikipedia.org/wiki/Electroacupuncture. Such electrical stimulation is known as electroacupuncture (EA). According to Acupuncture Today, a trade journal for acupuncturists: “Electroacupuncture is quite similar to traditional acupuncture in that the same points are stimulated during treatment. As with traditional acupuncture, needles are inserted on specific points along the body. The needles are then attached to an electrical device that generates continuous electric pulses using small clips. Such electrical device is used to adjust the frequency and intensity of the impulse being delivered, depending on the condition being treated. Electroacupuncture uses two needles at a time so that the impulses can pass from one needle to the other. Several pairs of needles can be stimulated simultaneously, usually for no more than 30 minutes at a time.” “Acupuncture Today: Electroacupuncture”. 2004 Feb. 1. (Retrieved on-line 2006 Aug. 9 at http://www.acupuncturetoday.com/abc/electroacupuncture.php.)
Recent research has reported the use of electroacupuncture (EA) for the treatment of hypertension. Li et al., “Neural Mechanism of Electroacupuncture's Hypotensive Effects”, Autonomic Neuroscience: Basic and Clinical 157 (2010) 24-30. Such report indicates that Chinese and Southeast Asian medical professionals have long utilized acupuncture, and its potent and more standardized alternative, electroacupuncture (EA) to treat disease. EA is characterized in the report as being administered by a small electrical current through needles from a battery driven device.
The reason why acupuncture, including EA, has a depressor effect on some types of hypertension is discussed at length in Cheung, Mechanism of Acupuncture, 2001, chapter 5, previously incorporated herein by reference.
In U.S. Pat. No. 7,373,204, issued to Gelfand et al., entitled “Implantable Device and Method for Treatment of Hypertension”, there is disclosed a method and apparatus that treats hypertension with electrostimulation of peripheral nerves. A pacemaker-sized device is implanted in the fatty tissue of the patient, e.g., in the chest, and then long leads, with electrodes at their distal ends, are tunneled through body tissue so that the electrodes reside at a desired location. In one embodiment, the desired location where electrostimulation is applied is near the median nerve in the wrist of the patient, which corresponds to acupoints P5 and P6. Gelfand also recognizes that acupuncture, including electroacupuncture, has been used to treat hypertension. See, '204 patent (Gelfand et al,), col. 3, lines 43-60.
To use a device as described in Gelfand et al, to treat hypertension, a lead must be tunneled through the entire length of the patient's arm. Such a method is as invasive as, and suffers from most of the same problems as, the prior-described attempts at stimulation of the vital parts of the central nervous system. In addition, the complications associated with tunneling and removal of leads, which include infection, breakage, as well as the need to perform additional surgery, are not trivial.
Yet others have described similar techniques for using electrical devices, including external EA devices, for stimulating peripheral nerves and other body locations for treatment of various maladies. See, e.g., U.S. Pat. Nos. 4,535,784; 4,566,064; 5,195,517; 5,250,068; 5,251,637; 5,891,181; 6,393,324; 6,006,134; 7,171,266; and 7,171,266. The methods and devices disclosed in these patents, however, typically utilize either large implantable stimulators having long leads that must be tunneled through tissue to reach the desired stimulation site, or use external devices that must interface with implanted electrodes via percutaneous leads or wires passing through the skin. Such devices and methods are still far too invasive, or are ineffective, and thus subject to the same limitations and concerns, as are the previously described electrical stimulation devices.
From the above, it is seen that there is room for much improvement in the electroacupuncture art for treating hypertension and other patient maladies. In particular, it is seen that a much less invasive device and technique are needed for electroacupuncture stimulation of acupoints that does not require the continual use of needles inserted through the skin, or long insulated lead wires, for the purpose of treating hypertension.
One characterization of the invention described herein is an Implantable ElectroAcupuncture Device (IEAD) that treats hypertension through the application of electroacupuncture (EA) stimulation pulses at a specified acupoint of a patient. The IEAD includes: (1) a small IEAD housing having an electrode configuration thereon that includes at least two electrodes, (2) pulse generation circuitry located within the IEAD housing that delivers EA stimulation pulses to the patient's body tissue at the specified acupoint, (3) a primary battery also located within the IEAD housing that provides the operating power for the IEAD to perform its intended function, and (4) a sensor located within the IEAD housing that is responsive to operating commands wirelessly communicated to the IEAD from a non-implanted location, these operating commands allowing limited external control of the IEAD, such as ON/OFF and EA stimulation pulse amplitude adjustment.
In one preferred embodiment, the IEAD housing used as part of the invention is coin-sized and -shaped, having a nominal diameter of 23 mm, and a thickness of only 2 to 3 mm.
One preferred embodiment provides a symmetrical electrode configuration on the housing of the IEAD. Such symmetrical electrode configuration includes at least two electrodes, at least one of which is located substantially in the center of a first surface of the IEAD housing, and is referred to as a central electrode. The other electrode is symmetrically positioned around and at least 5 mm distant from the center of the central electrode, and is referred to as an annular or ring electrode (or, in some instances, as a circumscribing electrode). This symmetry between the central electrode and the annular electrode advantageously focuses the electric field, and hence the EA stimulation current created by application of an EA stimulation pulse to the electrodes, deep into the tissue below the central electrode, where the desired EA stimulation at the specified acupoint occurs. Hence, when implanted, the first surface of the IEAD housing is faced inwardly into the patient's tissue below the acupoint, and a second surface of the IEAD housing, on the opposite side of the housing from the first surface, is faced outwardly to the patient's skin. One preferred embodiment of the IEAD housing uses one centrally located cathode electrode on the first surface of the IEAD housing, and one ring anode electrode located on a perimeter edge of a coin-sized and -shaped IEAD housing.
The pulse generation circuitry located within the IEAD housing is coupled to the at least two electrodes. This pulse generation circuitry is configured to generate EA stimulation pulses in accordance with a specified stimulation regimen. This stimulation regimen defines the duration and rate at which a stimulation session is applied to the patient. The stimulation regimen requires that the stimulation session have a duration of no more than T3 minutes and a rate of occurrence of no more than once every T4 minutes. Advantageously, the duty cycle of the stimulation sessions, i.e., the ratio of T3/T4, is very low, no greater than 0.05. A representative value for T3 is 30 minutes, and a representative value for T4 is 7 days. The individual EA stimulation pulses that occur within the stimulation session also have a duty cycle measured relative to the duration T3 of the stimulation session of no greater than 5%. A representative pulse width and frequency for the EA stimulation pulses is 0.5 milliseconds, occurring at a pulse rate of 2 Hz.
The primary battery contained within the IEAD housing and electrically coupled to the pulse generation circuitry has a nominal output voltage of 3 volts, and an internal battery impedance that is at least 5 ohms, and may be as high as 150 ohms or more. Advantageously, electronic circuitry within the IEAD housing controls the value of the instantaneous surge current that may be drawn from the battery in order to prevent any large drops in the battery output voltage. Avoiding large drops in the battery output voltage assures that the circuits within the IEAD will continue to operate as designed without failure. Being able to use a primary battery that has a relatively high internal impedance allows the battery to be thinner, and thus allows the device to be thinner and more easily implanted. The higher internal impedance also opens the door to using relatively inexpensive commercially-available disc batteries as the primary battery within the IEAD, thereby greatly enhancing the manufacturability of the IEAD and significantly lowering its cost.
Another characterization of the invention described herein may be described as a first method of treating hypertension in a patient using a leadless, coin-sized implantable electroacupuncture device (IEAD). Such IEAD is powered by a small disc battery having a specified nominal output voltage of about 3.0 volts, and having an internal impedance of at least 5 ohms.
The IEAD used to practice this first method is configured, using electronic circuitry within the IEAD, to generate EA stimulation pulses in accordance with a specified stimulation regimen. The EA stimulation pulses generated in accordance with this stimulation regimen are applied to the patient's tissue through at least two electrodes located on the housing of the IEAD. These two electrodes include at least one central electrode, located in the center of a bottom surface of the coin-sized housing, and at least one annular electrode that surrounds the central electrode. The edge of the annular electrode closest to the central electrode is separated from the center of the central electrode by at least 5 mm.
Using such an IEAD, the hypertension treatment method provided by this first method includes the steps of: (a) implanting the IEAD below the skin surface of the patient at a selected acupoint; and (b) enabling the IEAD to provide stimulation pulses in accordance with a stimulation regimen.
To elaborate regarding the first step of the method, the selected acupoint is preferably selected from the group of acupoints comprising PC5 or PC6 (in the right or left forearm), and S36 or S37 (in the left or right leg shin, just below the knee). When the IEAD is implanted, it is done so with its bottom surface (the “bottom” surface is that surface on which the central electrode is placed) facing into the patient's tissue below the patient's skin surface at the selected acupoint.
To elaborate regarding the second step of the method, the stimulation regimen provides a stimulation session at a rate of once every T4 minutes, with each stimulation session having a duration of T3 minutes. The ratio of T3/T4 is no greater than 0.05. A preferred stimulation session time T3 is 30 minutes, but T3 could be as short as 10 minutes or as long as 60 minutes. A preferred time between stimulation sessions T4 is 7 days, but it could be as short as ½ day or as long as 10 days, or longer, as needed to suit the needs of a particular patient.
Still further, the invention described herein may be characterized as a second method for treating hypertension in a patient. This second method comprises the steps of: (a) implanting a coin-sized electroacupuncture (EA) device in the patient just below the patient's skin at a specified acupoint; (b) enabling the EA device to generate EA stimulation sessions at a duty cycle that is less than 0.05, wherein each stimulation session comprises a series of EA stimulation pulses; and (c) delivering the EA stimulation pulses of each stimulation session to the specified acupoint through at least two electrodes attached to an outside surface of the EA device. The duty cycle is the ratio of T3/T4, where T3 is the duration in minutes of each stimulation session, and T4 is the time in minutes between stimulation sessions.
In a preferred application for this second method, the electrodes attached to the outside surface of the EA device are arranged in a symmetrical pattern. This symmetrical pattern of electrodes advantageously concentrates, or focuses, the electric field emanating from the electrode(s) downward into the tissue below the selected acupoint to a location where the electroacupuncture stimulation is most effective. Another preferred application is for the electrodes to be aligned along the axis of two or more acupoints. For treating hypertension, the specified acupoint at which the stimulation pulses are applied is preferably selected from the group of acupoints that includes: PC5 and/or PC6 in the right or left forearm. For some patients, the acupoints ST36 and/or ST37 in the left or right leg shin, just below the knee may also be added to the group.
Additionally, the invention described herein may be characterized as a method of assembling an implantable electroacupuncture device (IEAD) in a round, thin, hermetically-sealed, coin-sized housing that electrically and thermally isolates a feed-through pin assembly radially passing through a wall of the coin-sized housing from the high temperatures associated with welding the housing closed to hermetically seal its contents. Such method of assembling includes the steps of:
The above and other aspects, features and advantages of the invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings. These drawings illustrate various embodiments of the principles described herein and are part of the specification. The illustrated embodiments are merely examples and do not limit the scope of the disclosure.
Appendix A, submitted with one or more of Applicant's parent applications, illustrates some examples of alternate symmetrical electrode configurations that may be used with an IEAD of the type described herein.
Appendix B, also submitted with one or more of Applicant's parent applications, illustrates a few examples of non-symmetrical electrode configurations that may be used with an IEAD made in accordance with the teachings herein.
Appendix C, also submitted with one or more of Applicant's parent applications, shows an example of the code used in the micro-controller IC (e.g., U2 in
Appendix D, also submitted with one or more of Applicant's parent applications, contains selected pages from the WHO Standard Acupuncture Point Locations 2008 reference book.
Appendices A, B, C and D are incorporated by reference herein, and comprise a part of the specification of this patent application.
Throughout the drawings and appendices, identical reference numbers designate similar, but not necessarily identical, elements.
Disclosed and claimed herein is an implantable, coin-shaped, self-contained, symmetrical, leadless electroacupuncture (EA) device having at least two electrode contacts mounted on the surface of its housing. In one preferred embodiment, the electrodes include a central cathode electrode on a bottom side of the housing, and an annular anode electrode that surrounds the cathode. In another preferred embodiment, the anode annular electrode is a ring electrode placed around the perimeter edge of the coin-shaped housing.
The EA device is leadless. This means there are no leads or electrodes at the distal end of leads (common with most implantable electrical stimulators) that have to be positioned and anchored at a desired stimulation site. Also, because there are no leads, no tunneling through body tissue or blood vessels is required in order to provide a path for the leads to return and be connected to a tissue stimulator (also common with most electrical stimulators).
The EA device is adapted to be implanted through a very small incision, e.g., less than 2-3 cm in length, directly adjacent to a selected acupuncture site (“acupoint”) known to moderate or affect a hypertension condition of a patient.
The EA device is easy to implant. Also, most embodiments are symmetrical. This means that there is no way that it can be implanted incorrectly (unless the physician puts it in up-side-down, which would be difficult to do given the markings on its case). All that need be done is to cut the incision, and slide the device in place through the incision. Once the implant pocket has been prepared, it is as easy as sliding a coin into a slot. Such implantation can usually be completed in less than 10 minutes in an outpatient setting, or in a doctor's office. Only minor, local anesthesia need be used. No major or significant complications are envisioned for the implant procedure. The EA device can also be easily and quickly explanted, if needed.
The EA device is self-contained. It includes a primary battery to provide its operating power. It includes all of the circuitry it needs, in addition to the battery, to allow it to perform its intended function for several years. Once implanted, the patient will not even know it is there, except for a slight tingling that may be felt when the device is delivering stimulus pulses during a stimulation session. Also, once implanted, the patient can just forget about it. There are no complicated user instructions that must be followed. Just turn it on. No maintenance is needed. Moreover, should the patient want to disable the EA device, i.e., turn it OFF, or change stimulus intensity, he or she can do so using, e.g., an external magnet.
The EA device can operate for several years because it is designed to be very efficient. Stimulation pulses applied by the EA device at a selected acupoint through its electrodes formed on its case are applied at a very low duty cycle in accordance with a specified stimulation regimen. The stimulation regimen applies EA stimulation during a stimulation session that lasts at least 10 minutes, typically 30 minutes, and rarely longer than 60 minutes. These stimulation sessions, however, occur at a very low duty cycle. In one preferred treatment regimen, for example, a stimulation session having a duration of 30 minutes is applied to the patient just once a week. The stimulation regimen, and the selected acupoint at which the stimulation is applied, are designed and selected to provide efficient and effective EA stimulation for the treatment of the patient's hypertension condition.
The EA device is, compared to most implantable medical devices, relatively easy to manufacture and uses few components. This not only enhances the reliability of the device, but helps keep the manufacturing costs low, which in turn allows the device to be more affordable to the patient. One key feature included in the mechanical design of the EA device is the use of a radial feed-through assembly to connect the electrical circuitry inside of its housing to one of the electrodes on the outside of the housing. The design of this radial feed-through pin assembly greatly simplifies the manufacturing process. The process places the temperature sensitive hermetic bonds used in the assembly—the bond between a pin and an insulator and the bond between the insulator and the case wall—away from the perimeter of the housing as the housing is hermetically sealed at the perimeter with a high temperature laser welding process, thus preserving the integrity of the hermetic bonds that are part of the feed-through assembly.
In operation, the EA device is safe to use. There are no horrific failure modes that could occur. Because it operates at a very low duty cycle (i.e., it is OFF much, much more than it is ON), it generates little heat. Even when ON, the amount of heat it generates is not much, less than 1 mW, and is readily dissipated. Should a component or circuit inside of the EA device fail, the device will simply stop working. If needed, the EA device can then be easily explanted.
Another key feature included in the design of the EA device is the use of a commercially-available battery as its primary power source. Small, thin, disc-shaped batteries, also known as “coin cells,” are quite common and readily available for use with most modern electronic devices. Such batteries come in many sizes, and use various configurations and materials. However, insofar as applicants are aware, such batteries have never been used in implantable medical devices previously. This is because their internal impedance is, or has always thought to have been, much too high for such batteries to be of practical use within an implantable medical device where power consumption must be carefully monitored and managed so that the device's battery will last as long as possible, and so that dips in the battery output voltage (caused by any sudden surge in instantaneous battery current) do not occur that could compromise the performance of the device. Furthermore, the energy requirements of other active implantable therapies are far greater than can be provided by such coin cells without frequent replacement.
The EA device disclosed herein advantageously employs power-monitoring and power-managing circuits that prevent any sudden surges in battery instantaneous current, or the resulting drops in battery output voltage, from ever occurring, thereby allowing a whole family of commercially-available, very thin, high-output-impedance, relatively low capacity, small disc batteries (or “coin cells”) to be used as the EA device's primary battery without compromising the EA device's performance. As a result, instead of specifying that the EA device's battery must have a high capacity, e.g., greater than 200 mAh, with an internal impedance of, e.g., less than 5 ohms, which would either require a thicker battery and/or preclude the use of commercially-available coin-cell batteries, the EA device of the present invention can readily employ a battery having a relatively low capacity, e.g., less than 60 mAh, and a high battery impedance, e.g., greater than 5 ohms.
Moreover, the power-monitoring, power-managing, as well as the pulse generation, and control circuits used within the EA device are relatively simple in design, and may be readily fashioned from commercially-available integrated circuits (IC's) or application-specific integrated circuits (ASIC's), supplemented with discrete components, as needed. In other words, the electronic circuits employed within the EA device need not be complex nor expensive, but are simple and inexpensive, thereby making it easier to manufacture the EA device and to provide it to patients at an affordable cost.
As used herein, “annular”, “circumferential”, “circumscribing”, “surrounding” or similar terms used to describe an electrode or electrode array, or electrodes or electrode arrays, (where the phrase “electrode or electrode array,” or “electrodes or electrode arrays,” is also referred to herein as “electrode/array,” or “electrodes/arrays,” respectively) refers to an electrode/array shape or configuration that surrounds or encompasses a point or object, such as another electrode, without limiting the shape of the electrode/array or electrodes/arrays to be circular or round. In other words, an “annular” electrode/array (or a “circumferential” electrode/array, or a “circumscribing” electrode/array, or a “surrounding” electrode/array), as used herein, may be many shapes, such as oval, polygonal, starry, wavy, and the like, including round or circular.
“Nominal” or “about” when used with a mechanical dimension, e.g., a nominal diameter of 23 mm, means that there is a tolerance associated with that dimension of no more than plus or minus (+/−) 5%. Thus, a dimension that is nominally 23 mm means a dimension of 23 mm +/− (0.05×23 mm=1.15 mm).
“Nominal” when used to specify a battery voltage is the voltage by which the battery is specified and sold. It is the voltage you expect to get from the battery under typical conditions, and it is based on the battery cell's chemistry. Most fresh batteries will produce a voltage slightly more than their nominal voltage. For example, a new nominal 3 volt lithium coin-sized battery will measure more than 3.0 volts, e.g., up to 3.6 volts under the right conditions. Since temperature affects chemical reactions, a fresh warm battery will have a greater maximum voltage than a cold one. For example, as used herein, a “nominal 3 volt” battery voltage is a voltage that may be as high as 3.6 volts when the battery is brand new, but is typically between 2.7 volts and 3.4 volts, depending upon the load applied to the battery (i.e., how much current is being drawn from the battery) when the measurement is made and how long the battery has been in use.
Turning first to
As used herein, the “top” side of the IEAD 100 is the side that is positioned closest to the skin of the patient when the IEAD is implanted. The “bottom” side is the side of the IEAD that is farthest away from the skin when the IEAD is implanted. The “edge” of the IEAD is the side that connects or joins the top side to the bottom side. In
Many of the features associated with the mechanical design of the IEAD 100 shown in
It should be noted here that throughout this application, the terms IEAD 100, IEAD housing 100, bottom case 124, can 124, or IEAD case 124, or similar terms, are used interchangeably to mean the same thing. The context should dictate what is meant by these terms when used interchangeably. As the drawings illustrate, particularly
The embodiment of the IEAD 100 shown in
Not visible in
In contrast to the feed-through pin that establishes electrical contact with the anode electrode, electrical connection with the cathode electrode 110 is established simply by forming or attaching the cathode electrode 110 to the bottom 106 of the IEAD case 124. In order to prevent the entire case 124 from functioning as the cathode (which is done to better control the electric fields established between the anode and cathode electrodes), the entire IEAD housing is covered in a layer of silicone molding 125 (see
The advantage of using a central cathode electrode and a ring anode electrode is described in U.S. Provisional Patent Application No. 61/672,257, filed 6 Mar. 2012, entitled “Electrode Configuration for Implantable Electroacupuncture Device”, which application is incorporated herein by reference. One significant advantage of this electrode configuration is that it is symmetrical. That is, when implanted, the surgeon or other medical personnel performing the implant procedure, need only assure that the cathode side of the IEAD 100 is facing down, i.e., facing deeper into the tissue, and that the IEAD is over the desired acupoint, or other tissue location, that is intended to receive the electroacupuncture (EA) stimulation. The orientation of the IEAD 100 is otherwise not important.
Implantation of the IEAD is illustrated in
It should be noted that while
The feed-through pin 130 is preferably made of pure platinum 99.95%. A preferred material for the insulator material 136 is Ruby or alumina. The IEAD case 124, and the cover 122, are preferably made from titanium. The feed-through assembly, including the feed-through pin 130, ruby/alumina insulator 136 and the case 124 are hermetically sealed as a unit by gold brazing. Alternatively, active metal brazing can be used. (Active metal brazing is a form of brazing which allows metal to be joined to ceramic without metallization.)
The hermeticity of the sealed IEAD housing is tested using a helium leak test, as is common in the medical device industry. The helium leak rate should not exceed 1×10−9 STD cc/sec at 1 atm pressure. Other tests are performed to verify the case-to-pin resistance (which should be at least 15×106 Ohms at 100 volts DC), the avoidance of dielectric breakdown or flashover between the pin and the case 124 at 400 volts AC RMS at 60 Hz and thermal shock.
One important advantage provided by the feed-through assembly shown in
Turning next to
Other components included in the IEAD assembly, but not necessarily shown or identified in
Also not shown in
Further shown in
When assembled, the insulating layer 129 is positioned underneath the ring anode electrode 120 so that the anode electrode does not short to the case 124. The only electrical connection made to the anode electrode 120 is through the distal tip of the feed-through pin 130. The electrical contact with the cathode electrode 110 is made through the case 124. However, because the entire IEAD is coated with a layer of silicone molding 125, except for the anode ring electrode 120 and the circular cathode electrode 110, all stimulation current generated by the IEAD 100 must flow between the exposed surfaces of the anode and cathode.
It is noted that while the preferred configuration described herein uses a ring anode electrode 120 placed around the edges of the IEAD housing, and a circular cathode electrode 110 placed in the center of the cathode side of the IEAD case 124, such an arrangement could be reversed, i.e., the ring electrode could be the cathode, and the circular electrode could be the anode.
Moreover, the location and shape of the electrodes may be configured differently than is shown in the one preferred embodiment described above in connection with
It is also noted that while one preferred embodiment has been disclosed herein that incorporates a round, or short cylindrical-shaped housing, also referred to as a coin-shaped housing, the invention does not require that the case 124 (which may also be referred to as a “container”), and its associated cover plate 122, be round. The case could just as easily be an oval-shaped, rectangular-shaped (e.g., square with smooth corners), polygonal-shaped (e.g., hexagon-, octagon-, pentagon-shaped), button-shaped (with convex top or bottom for a smoother profile) device. Any of these alternate shapes, or others, would still permit the basic principles of the invention to be used to help protect a feed-through assembly from being exposed to excessive heat during assembly, and to allow the thin device to provide the benefits described herein related to its manufacture, implantation and use. For example, as long as the device remains relatively thin, e.g., no more than about 2-3 mm, and does not have a maximum linear dimension greater than about 25 mm, then the device can be easily implanted in a pocket over the tissue area where the selected acupuoint(s) is located. As long as there is a recess in the wall around the perimeter of the case wherein the feed-through assembly may be mounted, which recess effectively moves the wall or edge of the case inwardly into the housing a safe thermal distance, as well as a safe residual weld stress distance, from the perimeter wall where a hermetically-sealed weld occurs, the principles of the invention apply.
Further, it should be noted that while the preferred configuration of the IEAD described herein utilizes a central electrode on one of its surfaces that is round, having a diameter of nominally 4 mm, such central electrode need not necessarily be round. It could be oval shaped, polygonal-shaped, or shaped otherwise, in which case its size is best defined by its maximum width, which will generally be no greater than about 7 mm.
Finally, it is noted that the electrode arrangement may be modified somewhat, and the desired attributes of the invention may still be achieved. For example, as indicated previously, one preferred electrode configuration for use with the invention utilizes a symmetrical electrode configuration, e.g., an annular electrode of a first polarity that surrounds a central electrode of a second polarity. Such a symmetrical electrode configuration makes the implantable electroacupuncture device (IEAD) relatively immune to being implanted in an improper orientation relative to the body tissue at the selected acupoint(s) that is being stimulated. However, an electrode configuration that is not symmetrical may still be used and many of the therapeutic effects of the invention may still be achieved. For example, two spaced-apart electrodes on a bottom surface of the housing, one of a first polarity, and a second of a second polarity, could still, when oriented properly with respect to a selected acupoint tissue location, provide some desired therapeutic results
In the lower left corner of
Note, as has already been described above, the phrase “electrode or electrode array,” or “electrodes or electrode arrays,” may also be referred to herein as “electrode/array” or “electrodes/arrays,” respectively. For the ease of explanation, when an electrode array is referred to herein that comprises a plurality (two or more) of individual electrodes of the same polarity, the individual electrodes of the same polarity within the electrode array may also be referred to as “individual electrodes”, “segments” of the electrode array, “electrode segments”, or just “segments”.
In the lower right corner of
In the upper right corner of
The electrode configurations I, II, III and IV shown schematically in
Additionally, the polarities of the electrode/arrays may be selected as needed. That is, while the central electrode/array 310 is typically a cathode (−), and the surrounding electrode/array 320 is typically an anode (+), these polarities may be reversed.
It should be noted that the shape of the circumferential electrode/array, whether circular, oval, or other shape, need not necessarily be the same shape as the IEAD housing, unless the circumferential electrode/array is attached to a perimeter edge of the IEAD housing. The IEAD housing may be round, or it may be oval, or it may have a polygon shape, or other shape, as needed to suit the needs of a particular manufacturer and/or patient.
Additional electrode configurations, both symmetrical electrode configurations and non-symmetrical electrode configurations, that may be used with an EA stimulation device as described herein, are described in Appendices A and B of Applicant's parent application, application Ser. No. 13/598,575, incorporated herein by reference.
Next, with reference to
As controlled by the control circuit 210, the output circuit 202 of the IEAD 100 generates a sequence of stimulation pulses that are delivered to electrodes E1 and E2, through feed-through terminals 206 and 207, respectively, in accordance with a prescribed stimulation regimen. A coupling capacitor CC is also employed in series with at least one of the feed-through terminals 206 or 207 to prevent DC (direct current) current from flowing into the patient's body tissue.
As explained more fully below in connection with the description of
In one preferred embodiment, the electrodes E1 and E2 form an integral part of the housing 124. That is, electrode E2 may comprise a circumferential anode electrode that surrounds a cathode electrode E1. The cathode electrode E1, for the embodiment described here, is electrically connected to the case 124 (thereby making the feed-through terminal 206 unnecessary).
In a second preferred embodiment, particularly well-suited for implantable electrical stimulation devices, the anode electrode E2 is electrically connected to the case 124 (thereby making the feed-through terminal 207 unnecessary). The cathode electrode E1 is electrically connected to the circumferential electrode that surrounds the anode electrode E2. That is, the stimulation pulses delivered to the target tissue location (i.e., to the selected acupoint) through the electrodes E1 and E2 are, relative to a zero volt ground (GND) reference, negative stimulation pulses, as shown in the waveform diagram near the lower right hand corner of
Thus, in the embodiment described in
The battery 115 provides all of the operating power needed by the EA device 100. The battery voltage VBAT is not the optimum voltage needed by the circuits of the EA device, including the output circuitry, in order to efficiently generate stimulation pulses of amplitude, e.g., −VA volts. The amplitude VA of the stimulation pulses is typically many times greater than the battery voltage VBAT. This means that the battery voltage must be “boosted”, or increased, in order for stimulation pulses of amplitude VA to be generated. Such “boosting” is done using the boost converter circuit 200. That is, it is the function of the Boost Converter circuit 200 to take its input voltage, VBAT, and convert it to another voltage, e.g., VOUT, which voltage VOUT is needed by the output circuit 202 in order for the IEAD 100 to perform its intended function.
The IEAD 100 shown in
A boost converter integrated circuit (IC) typically draws current from its power source in a manner that is proportional to the difference between the actual output voltage VOUT and a set point output voltage, or feedback signal. A representative boost converter circuit that operates in this manner is shown in
In the boost converter circuit example shown in
Referring to the waveform in
Disadvantageously, however, a battery with higher internal impedance (e.g., 160 Ohms), cannot source more than a milliampere or so of current without a significant drop in output voltage. This problem is depicted in the timing waveform diagram shown in
As seen in
Also, it should be noted that although the battery used in the boost converter circuit is modeled in
In a suitably small and thin implantable electroacupuncture device (IEAD) of the type disclosed herein, it is desired to use a higher impedance battery in order to assure a small and thin device, keep costs low, and/or to have low self-discharge rates. The battery internal impedance also typically increases as the battery discharges. This can limit the service life of the device even if a new battery has acceptably low internal impedance. Thus, it is seen that for the IEAD 100 disclosed herein to reliably perform its intended function over a long period of time, a circuit design is needed for the boost converter circuit that can manage the instantaneous current drawn from VIN of the battery. Such current management is needed to prevent the battery's internal impedance from causing VIN to drop to unacceptably low levels as the boost converter circuit pumps up the output voltage VOUT and when there is high instantaneous output current demand, as occurs when EA stimulation pulses are generated.
To provide this needed current management, the IEAD 100 disclosed herein employs electronic circuitry as shown in
In the circuitry shown in
The switches SP and SR, shown in
At the leading edge of a stimulus pulse, the switch SP is closed, which immediately causes a negative voltage −VOUT to appear across the load, RLOAD, causing the voltage at the anode E1 to also drop to approximately −VOUT, thereby creating the leading edge of the stimulus pulse. This voltage starts to decay back to 0 volts as controlled by an RC (resistor-capacitance) time constant that is long compared with the desired pulse width. At the trailing edge of the pulse, before the voltage at the anode E1 has decayed very much, the switch SP is open and the switch SR is closed. This action causes the voltage at the anode E1 to immediately (relatively speaking) return to 0 volts, thereby defining the trailing edge of the pulse. With the switch SR closed, the charge on the circuit side of the coupling capacitor CC is allowed to charge back to VOUT within a time period controlled by a time constant set by the values of capacitor CC and resistor R3. When the circuit side of the coupling capacitor CC has been charged back to VOUT, then switch SR is opened, and both switches SR and SP remain open until the next stimulus pulse is to be generated. Then the process repeats each time a stimulus pulse is to be applied across the load.
Thus, it is seen that in one embodiment of the electronic circuitry used within the IEAD 100, as shown in
An alternate embodiment of the electronic circuitry that may be used within the IDEA 100 is shown in
A low level digital control signal that performs this function of enabling (turning ON) or disabling (turning OFF) the boost converter circuit is depicted in
A refinement to the alternate embodiment shown in
One preferred embodiment of the circuitry used in an implantable electroacupuncture device (IEAD) 100 that employs a digital control signal as taught herein is shown in the schematic diagram shown in
The IC U2 is a micro-controller IC and is used to perform the function of the control circuit 220 described previously in connection with
The micro-controller U2 primarily performs the function of generating the digital signal that shuts down the boost converter to prevent too much instantaneous current from being drawn from the battery VBAT. The micro-controller U2 also controls the generation of the stimulus pulses at the desired pulse width and frequency. It further keeps track of the time periods associated with a stimulation session, i.e., when a stimulation session begins and when it ends.
The micro-controller U2 also controls the amplitude of the stimulus pulse. This is done by adjusting the value of a current generated by a Programmable Current Source U3. In one embodiment, U3 is realized with a voltage controlled current source IC. In such a voltage controlled current source, the programmed current is set by a programmed voltage appearing across a fixed resistor R5, i.e., the voltage appearing at the “OUT” terminal of U3. This programmed voltage, in turn, is set by the voltage applied to the “SET” terminal of U3. That is, the programmed current source U3 sets the voltage at the “OUT” terminal to be equal to the voltage applied to the “SET” terminal. The programmed current that flows through the resistor R5 is then set by Ohms Law to be the voltage at the “set” terminal divided by R5. As the voltage at the “set” terminal changes, the current flowing through resistor R5 at the “OUT” terminal changes, and this current is essentially the same as the current pulled through the closed switch M1, which is essentially the same current flowing through the load RLOAD. Hence, whatever current flows through resistor R5, as set by the voltage across resistor R5, is essentially the same current that flows through the load RLOAD. Thus, as the micro-controller U2 sets the voltage at the “set” terminal of U3, on the signal line labeled “AMPSET”, it controls what current flows through the load RLOAD. In no event can the amplitude of the voltage pulse developed across the load RLOAD exceed the voltage VOUT developed by the boost converter less the voltage drops across the switches and current source.
The switches SR and SP described previously in connection with
The circuitry shown in
It is also important that the circuitry used in the IEAD 100, e.g., the circuitry shown in
Still referring to
Use of the ECD 240 provides a way for the patient, or medical personnel, to control the IEAD 100 after it has been implanted (or before it is implanted) with some simple commands, e.g., turn the IEAD ON, turn the IEAD OFF, increase the amplitude of the stimulation pulses by one increment, decrease the amplitude of the stimulation pulses by one increment, and the like. A simple coding scheme may be used to differentiate one command from another. For example, one coding scheme is time-based. That is, a first command is communicated by holding a magnet near the IEAD 100, and hence near the magnetic sensor U4 contained within the IEAD 100, for differing lengths of time. If, for example, a magnet is held over the IEAD for at least 2 seconds, but no more than 7 seconds, a first command is communicated. If a magnet is held over the IEAD for at least 11 seconds, but no more than 18 seconds, a second command is communicated, and so forth.
Another coding scheme that could be used is a sequence-based coding scheme. That is, application of 3 magnetic pulses may be used to signal one external command, if the sequence is repeated 3 times. A sequence of 2 magnetic pulses, repeated twice, may be used to signal another external command. A sequence of one magnetic pulse, followed by a sequence of two magnetic pulses, followed by a sequence of three magnetic pulses, may be used to signal yet another external command.
Other simple coding schemes may also be used, such as the letters AA, RR, HO, BT, KS using international Morse code. That is, the Morse code symbols for the letter “A” are dot dash, where a dot is a short magnetic pulse, and a dash is a long magnetic pulse. Thus, to send the letter A to the IEAD 100 using an external magnet, the user would hold the magnet over the area where the IEAD 100 is implanted for a short period of time, e.g., one second or less, followed by holding the magnet over the IEAD for a long period of time, e.g., more than one second.
More sophisticated magnetic coding schemes may be used to communicate to the micro-controller chip U2 the operating parameters of the IEAD 100. For example, using an electromagnet controlled by a computer, the pulse width, frequency, and amplitude of the EA stimulation pulses used during each stimulation session may be pre-set. Also, the frequency of the stimulation sessions can be pre-set. Additionally, a master reset signal can be sent to the device in order to re-set these parameters to default values. These same operating parameters and commands may be re-sent at any time to the IEAD 100 during its useful lifetime should changes in the parameters be desired or needed.
The current and voltage waveforms associated with the operation of the IEAD circuitry of
Referring to
The electroacupuncture (EA) simulation pulses resulting from operation of the circuit of
Another preferred embodiment of the circuitry used in an implantable electroacupuncture device (IEAD) 100 that employs a digital control signal as taught herein is shown in the schematic diagram of
The Schottky diode D5 helps isolate the output voltage VOUT generated by the boost converter circuit U1. This is important in applications where the boost converter circuit U1 is selected and operated to provide an output voltage VOUT that is four or five times as great as the battery voltage, VBAT. For example, in the embodiment for which the circuit of
The inclusion of the fifth IC U5 in the circuit shown in
The IC U5 shown in
From the above description, it is seen that an implantable IEAD 100 is provided that uses a digital control signal to duty-cycle limit the instantaneous current drawn from the battery by a boost converter. Three different exemplary configurations (
Delta-sigma modulation is well described in the art. Basically, it is a method for encoding analog signals into digital signals or higher-resolution digital signals into lower-resolution digital signals. The conversion is done using error feedback, where the difference between the two signals is measured and used to improve the conversion. The low-resolution signal typically changes more quickly than the high-resolution signal and it can be filtered to recover the high resolution signal with little or no loss of fidelity. Delta-sigma modulation has found increasing use in modern electronic components such as converters, frequency synthesizers, switched-mode power supplies and motor controllers. See, e.g., Wikipedia, Delta-sigma modulation.
With the implantable electroacupuncture device (IEAD) 100 in hand, the IEAD 100 may be used most effectively to treat hypertension by first pre-setting stimulation parameters that the device will use during a stimulation session.
Turning next to
By way of example, one set of parameters that could be used to define a stimulation regimen is
It is to be emphasized that the values shown above for the stimulation regimen are representative of only one preferred stimulation regimen that could be used. Other stimulation regimens that could be used, and the ranges of values that could be used for each of these parameters, are as defined in the claims.
It is also emphasized that the ranges of values presented in the claims for the parameters used with the invention have been selected after many months of careful research and study, and are not arbitrary. For example, the ratio of T3/T4, which sets the duty cycle, has been carefully selected to be very low, e.g., no more than 0.05. Maintaining a low duty cycle of this magnitude represents a significant change over what others have attempted in the implantable stimulator art. Not only does a very low duty cycle allow the battery life to be extended, which in turn allows the IEAD housing to be very small, which makes the IEAD ideally suited for being used without leads, thereby making it relatively easy to implant the device at the desired acupuncture site, but it also limits the frequency and duration of stimulation sessions. Limiting the frequency and duration of the stimulation sessions is a key aspect of applicants' invention because it recognizes that some treatments, such as treating hypertension, are best done slowly and methodically, over time, rather than quickly and harshly using large doses of stimulation (or other treatments) aimed at forcing a rapid change in the patient's condition. Moreover, applying treatments slowly and methodically is more in keeping with traditional acupuncture methods (which, as indicated previously, are based on over 2500 years of experience). In addition, this slow and methodical conditioning is consistent with the time scale for remodeling of the central nervous system needed to produce the sustained therapeutic effect. Thus, applicants have based their treatment regimens on the slow-and-methodical approach, as opposed to the immediate-and-forced approach adopted by many, if not most, prior art implantable electrical stimulators.
Once the stimulation regimen has been defined and the parameters associated with it have been pre-set into the memory of the micro-controller circuit 220, the IEAD 100 needs to be implanted. Implantation is a simple procedure, and is described above in connection with the description of
For treating hypertension, the specified acupoint at which the EA stimulation pulses should be applied in accordance with a selected stimulation regimen is at least one of the following acupoints: PC5 or PC6 in the right or left wrist; or ST36 or ST37 in the left or right leg, just below the knee.
After implantation, the IEAD must be turned ON, and otherwise controlled, so that the desired stimulation regimen may be carried out. In one preferred embodiment, control of the IEAD after implantation, as well as anytime after the housing of the IEAD has been hermetically sealed, is performed as shown in the state diagram of
Shelf Mode is a low power state in which the IEAD is placed prior to shipment. After implant, commands are made through magnet application. Magnet application means an external magnet, typically a small hand-held cylindrical magnet, is placed over the location where the IEAD has been implanted. With a magnet in that location, the magnetic sensor U4 senses the presence of the magnet and notifies the controller U2 of the magnet's presence.
From the “Shelf Mode” state, a magnet application for 10 seconds (M.10 s) puts the IEAD in the “Set Amplitude” state. While in the “Set Amplitude” state, the stimulation starts running by generating pulses at zero amplitude, incrementing every five seconds until the patient indicates that a comfortable level has been reached. At that time, the magnet is removed to set the amplitude.
If the magnet is removed and the amplitude is non-zero (
The Triggered Session ends and stimulation stops after the session time (TS) has elapsed and the device enters the “Sleep” state. If a magnet is applied during a Triggered Session (M), the session aborts to the “OFF” state. If the magnet remains held on for 10 seconds (M.10 s) while in the “OFF” state, the “Set Amplitude” state is entered with the stimulation level starting from zero amplitude as described.
If the magnet is removed (
While in the Sleep state, if a magnet has not been applied in the last 30 seconds (D) and a magnet is applied for a window between 20-25 seconds and then removed (M.20:25 s), a Triggered Session is started. If the magnet window is missed (i.e. magnet removed too soon or too late), the 30 second de-bounce period (D) is started. When de-bounce is active, no magnet must be detected for 30 seconds before a Triggered Session can be initiated.
The session interval timer runs while the device is in Sleep state. The session interval timer is initialized when the device is woken up from Shelf Mode and is reset after each session is completely delivered. Thus abort of a triggered session by magnet application will not reset the timer, the Triggered Session must be completely delivered.
The circuitry that sets the various states shown in
The preceding description has been presented only to illustrate and describe some embodiments of the invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. Thus, while the invention(s) herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention(s) set forth in the claims.
The present application is a divisional application of U.S. patent application Ser. No. 14/805,355, filed Jul. 21, 2015, which is a continuation application of U.S. patent application Ser. No. 14/446,500, filed Jul. 30, 2014 and issued as U.S. Pat. No. 9,358,382, which application is a divisional application of U.S. patent application Ser. No. 13/598,575, filed Aug. 29, 2012 and issued as U.S. Pat. No. 8,805,512. U.S. patent application Ser. No. 13/598,575 also claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 61/575,869, filed Aug. 30, 2011; U.S. Provisional Patent Application No. 61/606,995, filed Mar. 6, 2012; U.S. Provisional Patent Application No. 61/609,875, filed Mar. 12, 2012; U.S. Provisional Patent Application No. 61/672,257, filed Jul. 16, 2012; U.S. Provisional Patent Application No. 61/672,661, filed Jul. 17, 2012; U.S. Provisional Patent Application No. 61/674,691, filed Jul. 23, 2012; and U.S. Provisional Patent Application No. 61/676,275, filed Jul. 26, 2012. All of these applications are incorporated herein by reference in their respective entireties.
| Number | Date | Country | |
|---|---|---|---|
| 61575869 | Aug 2011 | US | |
| 61606995 | Mar 2012 | US | |
| 61609875 | Mar 2012 | US | |
| 61672257 | Jul 2012 | US | |
| 61672661 | Jul 2012 | US | |
| 61674691 | Jul 2012 | US | |
| 61676275 | Jul 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14805355 | Jul 2015 | US |
| Child | 15700013 | US | |
| Parent | 13598575 | Aug 2012 | US |
| Child | 14446500 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14446500 | Jul 2014 | US |
| Child | 14805355 | US |
