Patent Application
20090248106
The invention relates generally to electrophysiological stimulation. More particularly, the present invention relates to electrophysiological stimulation with a wireless system using optical-based communication and power transmission.
An electrophysiological stimulation device is a medical device that uses electrical impulses delivered by electrodes contacting muscles or nerves to regulate or stimulate their function. Applications for electrophysiological stimulation include artificial cardiac pacemakers and devices designed for neurostimulation. Many existing electrophysiological stimulation devices rely on a wired architecture where implanted leads are wired to a central device. For example, current designs for pacemakers use intravenously inserted pacing leads attached internally within the chambers of the heart and wires to link the leads to the pacemaker, which determines when electrical pulses are delivered. In another example, existing Implantable neurostimulator devices, incorporating pulse generators, provide electrical stimulation through wired leads implanted near the central nervous system, i.e. (the brain or spinal cord) or an affected peripheral nerve.
Wired electrophysiological stimulation systems face many difficulties with performance and infection to the patient. Under a wired architecture, there is limited flexibility in routing of the electric leads, especially to multiple locations. Wired intravenous cardiac devices for example, are especially problematic in those with limited body surface areas i.e. children and young adults. Thrombosis of the venous conduits and downstream embolization are recognized complications. Undue tension on vital structures can occur during somatic growth and the removal of wired devices is currently fraught with significant morbidity and mortality. Wired architecture is also limited in scalability. In addition, the large size of the implanted central device or leads can provide discomfort to the patient. When the central device is externally located and wired to the implanted leads, the probability of infection at the wire/skin interface remains high.
Wireless electrophysiological stimulation systems have been developed to overcome some of the above disadvantages of wired systems. Some wireless and leadless electrophysiological stimulation systems have been developed using RF/microwave and also ultrasonic acoustic technology. These devices use high-energy radio waves or ultrasonic waves from an external power source for wireless communication and also to recharge the battery in the implanted devices, or else to convert the incident RF/ultrasound energy directly into electrical power.
Though existing wireless electrophysiological systems overcome some of the disadvantages of wired systems, there remain many difficulties in these wireless systems. For implanted devices relying solely on internal batteries to operate, the longevity and power of the device is limited. Frequent surgical procedures would be required for higher battery usage applications. Though RF devices need not be surgically removed to recharge, they also face difficulties with electromagnetic interference. In addition, RF systems typically still require rechargeable batteries in the implanted devices to temporarily store charge in the devices. The wireless electrophysiological stimulation systems based on ultrasound technology can have safety issues related to prolonged exposure of biological tissues to ultrasound acoustic energy, and can be constrained by low transmission efficiencies, especially in internal body cavities. Adverse changes in cellular ultrastructure (thermal or cavitation damage) have been previously demonstrated.
The presence of a battery in an implantable device limits the miniaturization of the device. The large size of battery-powered (either rechargeable or non-rechargeable) devices often causes discomfort to the patient and increases the risk of nerve or tissue damage from external mechanical shocks. Furthermore, large devices face difficulties in deployment inside of the body, and raise the probability of infection.
The present invention addresses at least the difficult problems of electrophysiological stimulation and advances the art with a wireless system for providing electrical stimulation.
The present invention is directed to optical-based wireless devices, systems, and methods for electrophysiological stimulation. In a preferred embodiment, an implantable device, referred to as a trigger pod, is provided for delivering electrophysiological stimulation to a subject. The device includes a micro-power panel for receiving a wirelessly transmitted optical signal, wherein the optical signal includes infrared light, and wherein the micro-power panel converts the infrared light into electrical energy; an electronic circuit for generating electrical impulses, wherein the electronic circuit is powered by the electrical energy converted by the micro-power panel; and one or more electrodes, wherein the electrical impulses generated by the electronic circuit are delivered to the subject through the one or more electrodes, and wherein the device is implantable near a muscle, a tissue, or a nerve internal to the subject. Preferably, the device does not include a battery. In an embodiment, the device also includes a lens to focus the incident optical signal onto the micro-power panel.
In an embodiment, the micro-power panel includes one or more photodiodes and the optical signal received by the micro-power panel is a nearly collimated optical beam. In another embodiment, the micro-power panel receives a second optical signal for data transmission, wherein the second optical signal includes a modulated optical beam and directs the electronic circuit to control the intensity, the duration, the timing, or any combination thereof of the electrical impulses. Alternatively, the optical signal includes a modulated beam for both power and data transmission. In a preferred embodiment, the trigger pod is less than approximately 7 mm in width. In certain embodiments, the trigger pod includes an energy-harvesting module, wherein the energy-harvesting module uses vibrational or thermal energy to partially power the device.
The present invention is also directed to a wireless system for providing electrophysiological stimulation to a subject. The system includes an optical transmitter for transmitting optical signals and one or more implantable trigger pods, wherein each of the trigger pods includes: a micro-power panel for receiving the optical signals transmitted by the optical transmitter, wherein the micro-power panel converts the optical signal into electrical energy; an electronic circuit for generating electrical impulses, wherein the electronic circuit is powered by the electrical energy converted by the micro-power panel; and one or more electrodes, wherein the electrical impulses generated by the electronic circuit are delivered to the subject through the one or more electrodes, wherein the one or more trigger pods are implanted near a muscle (skeletal, smooth or cardiac), a tissue, or a nerve internal to the subject, and wherein the one or more trigger pods are wirelessly connected to the optical transmitter. In a preferred embodiment, the implantable trigger pods are battery-less.
In an embodiment, the optical transmitter includes a laser diode or a light-emitting diode for producing optical signals. The optical transmitter can also include one or more mirrors to direct the optical signals from the optical transmitter to the trigger pods. In an embodiment, the mirrors are rotatable. The optical transmitter can be implanted in the body of the subject or can be external to the subject. In another embodiment, the optical transmitter transmits a second optical signal, wherein the micro-power panel of one of the trigger pods receives the second optical signal, and wherein the second optical signal directs the electronic circuit of the same trigger pod to control the intensity, the duration, the timing, or any combination thereof of the electrical impulses.
In an embodiment, the system includes one or more optical fibers, wherein the optical transmitter transmits the optical signals to the trigger pods through the optical fibers. The optical fibers can be implanted in the body of the subject or can be located external to the subject. In an embodiment, the system includes a multi-furcated fused fiber bundle, wherein optical signals are delivered through the legs of the multi-furcated fused fiber bundle to the trigger pods. In an embodiment, an optical fiber has one or more controlled leakage locations, wherein the optical signals exit the optical fiber through the leakage locations and are transmitted to the trigger pods. In an embodiment, the system includes multiple optical transmitters that are communicatively connected.
Another embodiment of the present invention is directed to a method of providing electrophysiological stimulation to a subject. The method includes (1) providing an optical transmitter for transmitting optical signals; (2) implanting one or more trigger pods near a muscle (skeletal, smooth or cardiac), a tissue, or a nerve of the subject, wherein each of the trigger pods includes a micro-power panel for receiving the optical signals transmitted by the optical transmitter, wherein the micro-power panel converts the optical signal into electrical energy, an electronic circuit for generating electrical impulses, wherein the electronic circuit is powered by the electrical energy converted by the micro-power panel, and one or more electrodes, wherein the electrical impulses generated by the electronic circuit are delivered to the subject through the one or more electrodes; and (3) directing the optical transmitter to transmit said optical signals to the trigger pods, whereby the electrical impulses provide electrophysiological stimulation to the muscle, the tissue, or the nerve of the subject.
Another embodiment of the method further includes directing the optical transmitter to transmit a second optical signal to the trigger pods, wherein the micro-power panel of one of the trigger pods receives the second optical signal, and wherein the second optical signal directs the electronic circuit of the same trigger pod to control the intensity, the duration, the timing, or any combination thereof of the electrical impulses delivered by the same trigger pod.
In a preferred embodiment, at least one of the trigger pods is implanted near the heart of the subject, wherein the electrical impulses delivered by the same trigger pod are for treating dyrrhythmias. In another embodiment, at least one of the trigger pods is implanted near one of the nerves of the subject, wherein the electrical impulses delivered by the same trigger pods are for mimicking or blocking neurotransmission, i.e. pain relief to the subject.
The present invention together with its objectives and advantages will be understood by reading the following description in conjunction with the drawings, in which:
The present invention is directed to wireless optical-based electrophysiological stimulation. In embodiments of the present invention, electrophysiological stimulation can be used to provide relief to people suffering from a variety of conditions, such as neurological disorders, pain relief, spasms, and dysrrhythmia. It is noted that the present invention can be applied for stimulation of any nerve, tissue, or muscle of a human or non-human subject. The following includes a brief description of applications where the present invention can be applied, though it is noted that the present invention is not limited to these applications.
Electrical stimulation of the deep regions within the brain allows for the treatment of otherwise resistant movement disorders and affective disorders. The stimulation allows for the supporting elements of the brain to release adeonsine triphosphate. Neurohumoral changes can have a positive effect on behavior and emotions.
Deep brain stimulation can be used to treat chronic pain disorders, Parkinson's disease, tremors, dystonia, spasms, depression, and epilepsy. For example, for non-Parkinsonian essential tremor electrical stimulation can be applied to the ventrointermedial nucleus of the thalamus. For dystonia and symptoms related to Parkinson's disease stimulation of the globus pallidus or the subthalamic nucleus is desired.
Stimulation of the dorsal column of the spinal cord allows for the altered perception of pain. Stimulation frequently is either epidural or subcutaneous. Frequent applications include failed back syndrome, complex regional pain syndromes and peripheral neuropathies.
Neuralgia or nerve induced pain disorders can be treated by electrical stimulation of the peripheral nerve. Particular examples of pain disorders include occipital neuralgia, trigeminal neuralgia and glossopharyngeal neuralgias.
Neuralgia or nerve induced pain disorders can be treated by electrical stimulation of the peripheral nerve. Particular examples of pain disorders include median, ulnar and radial neuralgias.
Muscles can be stimulated to produce contraction of the stimulated muscle. Usages could include improved intestinal propulsion and external control of sphincters, such as the anus or the bladder neck.
Normal cardiac muscle stimulation occurs spontaneously via depolarization of the electrically active cells within the myocardium. The remaining cells are activated simultaneously as they remain connected together on a cellular level. When either an abnormal origin or rate of stimulation occurs, artificial electrical stimulation can correct the abnormality. Diseases that can be treated include bradyarrhythmias, tachyarrhythmias, bradytachyarrhythmias, abnormal rhythms originating from either the atria and/or the ventricles.
An embodiment of the present invention is directed to pacemaker applications where electrical stimulation is applied to surface of the heart (epicardial) or within the heart (endocardial). Indirect pacing of the systemic chambers of the heart can be accomplished internally by stimulating the coronary sinus, a venous structure that runs posterior to the systemic pumping chamber. The present invention can by design directly pace selected cardiac chambers, either in an epi- or endocardial configuration or in a combination thereof. Indirect pacing could be achieved if deemed necessary.
The present invention provides a wireless optical-link based system between a main controller with an optical transmitter and remote electrode assemblies, referred to as trigger pods. The optical connection between the transmitter and trigger pods can provide signal transmission, power transport, or both, to the implanted battery-less trigger pods. The present invention can be employed to treat any of the above conditions, or any other medical condition where electrical stimulation of nerves, muscle, and/or tissue is desired.
It is noted that in the embodiment of
An enlarged view of the trigger pod 110 is shown in
It is important to note that in a preferred embodiment, the trigger pod 110 is battery-less. In other words, the sole power source for the trigger pod 110 is the optical transmitter 120. The absence of an internal battery in the preferred embodiment enables miniaturization of the trigger pods, which reduces the risk of nerve or tissue damage from external mechanical shocks, lowers the chance of infection, and enables easier deployment inside of the body. In an embodiment, each of the trigger pods is less than approximately 7 mm in width. It is noted that in certain embodiments, the electronic circuit 230 includes capacitors for temporary charge storage or small internal batteries for temporary power storage.
The trigger pod 110 is an implantable device that is directly attached to tissue, muscle, or a nerve for neurostimulation. In an embodiment, the trigger pod is implanted at the desired site using a catheter-based process or a mini-surgical procedure. As noted above, the small size of the trigger pod in preferred embodiments allows for easy implantation.
In a preferred embodiment, the optical signal 350 contains optical wavelength light in the near infrared range of 810 nm to 880 nm, with a most preferred wavelength of approximately 850 nm. Near infrared light can penetrate tissue up to about 20 mm thick with acceptable levels of attenuation. The required penetration depth and appropriate wavelength is determined based on the relative position of the optical transmitter and the trigger pod. In an embodiment, the optical signal 350 is a nearly collimated optical beam, which may be modulated or un-modulated.
FIGS. 4 and 5A-B show examples of optical transmitters having optical elements such as a beamsplitter or a prism, or a beam steering assembly of micromechanical mirrors to direct the optical signal. In the embodiment shown in
The optical transmitter 430 includes one or more optical elements 490, such as a beamsplitter or a prism or a pivoted rotatable mirror, used for directing the optical signal to the trigger pods 410, 420. The optical element(s) 490 can be used to direct optical signals 460, 470 to multiple trigger pods 410, 420 simultaneously, or to alternately sweep between multiple trigger pods 410, 420. In a preferred embodiment, the optical element 490 is a pivoted rotatable mirror, with two separate rotational axes (pitch and yaw). By having a pivoted rotatable mirror, the transmission direction of the optical signals 460, 470 can be altered as needed, such as when new trigger pods are introduced or existing trigger pods are moved.
Though
An embodiment having optical fibers removes the line-of-sight constraint; since the optical fibers can be routed in various ways through or on the body, a line-of-sight configuration is not needed. In an embodiment, the optical fibers or optical fiber bundles have large glass or plastic cores and can have stripped buffers internally to improve packing efficiency. In certain embodiments, a biocompatible polymer buffer surrounds the fiber or bundle externally for protection and durability. Optical fiber diameters range from a few hundred microns to about 3-4 mm and their lengths range from a few inches to a few feet long. In an embodiment, the fiber bundles are routed intravenously or inside of a body cavity.
In embodiments of the present invention, such as the embodiments shown in
In an embodiment, the first (un-modulated) and second (modulated) optical signals can be superimposed or sent simultaneously. Alternatively, power and data transmission can be achieved by transmission of a single modulated optical beam. In this embodiment, the micro-power panel 220 of the trigger pod is capable of converting modulated optical signals into electrical power. Regardless of the nature and types of optical signals, combining power and data transmission allows an operator to have greater control over the electrophysiological stimulation treatment.
As one of ordinary skill in the art will appreciate, various changes, substitutions, and alterations could be made or otherwise implemented without departing from the principles of the present invention, e.g. any number of trigger pods, optical transmitters, and optical fibers can be used, and the components of the system can be either implanted or placed external to the subject. Accordingly, the scope of the invention should be determined by the following claims and their legal equivalents.
This application claims priority from U.S. Provisional Patent Application 61/070,705, Docket No. MDB-101/PROV, titled “Wireless-based Cardiac Pacing” and filed Mar. 24, 2008, which is incorporated herein by reference. This application also claims priority from US Provisional Patent Application Docket No. MDB-103/PROV, titled “Electrophysiological Stimulation System Using Optical Signals” and filed Mar. 5, 2009, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61070705 | Mar 2008 | US | |
| 61209525 | Mar 2009 | US |
