Dynamic cranial nerve stimulation based on brain state determination from cardiac data

Information

  • Patent Grant
  • 8768471
  • Patent Number
    8,768,471
  • Date Filed
    Sunday, March 3, 2013
    11 years ago
  • Date Issued
    Tuesday, July 1, 2014
    10 years ago
Abstract
A method of treating a medical condition in a patient using an implantable medical device, comprising providing an electrical signal generator; providing at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting the at least a first value. Also, a computer readable program storage device encoded with instructions that, when executed by a computer, performs the method. In addition, the implantable medical device used in the method.
Description
BACKGROUND OF THE INVENTION

This invention relates generally to medical device systems and, more particularly, to medical device systems for applying electrical signals to a cranial nerve for the treatment of various medical conditions exhibiting unstable brain states as determined by analysis of data from a patient's cardiac cycle.


Many advancements have been made in treating medical conditions involving or mediated by the neurological systems and structures of the human body. In addition to drugs and surgical intervention, therapies using electrical signals for modulating electrical activity of the body have been found to be effective for many medical conditions. In particular, medical devices have been effectively used to deliver therapeutic electrical signals to various portions of a patient's body (e.g., the vagus nerve) for treating a variety of medical conditions. Electrical signal therapy may be applied to a target portion of the body by an implantable medical device (IMD) that is located inside the patient's body or, alternatively, may be applied by devices located external to the body. In addition, some proposed devices include a combination of implanted and external components.


The vagus nerve (cranial nerve X) is the longest nerve in the human body. It originates in the brainstem and extends, through the jugular foramen, down below the head, to the abdomen. Branches of the vagus nerve innervate various organs of the body, including the heart, the stomach, the lungs, the kidneys, the pancreas, and the liver. In view of the vagus nerve's many functions, a medical device such as an electrical signal generator has been coupled to a patient's vagus nerve to treat a number of medical conditions. In particular, electrical signal therapy for the vagus nerve, often referred to as vagus nerve stimulation (VNS), has been approved in the United States and elsewhere to treat epilepsy and depression. In particular, application of an electrical signal to the vagus nerve is thought to modulate some areas in the brain that are prone to seizure activity.


Implantable medical devices (IMDs) have been effectively used to deliver therapeutic stimulation to various portions of the human body (e.g., the vagus nerve) for treating a variety of diseases. As used herein, “stimulation” or “stimulation signal” refers to the application of an electrical, mechanical, magnetic, electro-magnetic, photonic, audio and/or chemical signal to a neural structure in the patient's body. The signal is an exogenous signal that is distinct from the endogenous electrical, mechanical, and chemical activity (e.g., afferent and/or efferent electrical action potentials) generated by the patient's body and environment. In other words, the stimulation signal (whether electrical, mechanical, magnetic, electro-magnetic, photonic, audio or chemical in nature) applied to the nerve in the present invention is a signal applied from an artificial source, e.g., a neurostimulator.


A “therapeutic signal” refers to a stimulation signal delivered to a patient's body with the intent of treating a medical condition by providing a modulating effect to neural tissue. The effect of a stimulation signal on neuronal activity is termed “modulation”; however, for simplicity, the terms “stimulating” and “modulating”, and variants thereof, are sometimes used interchangeably herein. In general, however, the delivery of an exogenous signal itself refers to “stimulation” of the neural structure, while the effects of that signal, if any, on the electrical activity of the neural structure are properly referred to as “modulation.” The modulating effect of the stimulation signal upon the neural tissue may be excitatory or inhibitory, and may potentiate acute and/or long-term changes in neuronal activity. For example, the “modulating” effect of the stimulation signal to the neural tissue may comprise one more of the following effects: (a) initiation of an action potential (afferent and/or efferent action potentials); (b) inhibition or blocking of the conduction of action potentials, whether endogenous or exogenously induced, including hyperpolarizing and/or collision blocking, (c) affecting changes in neurotransmitter/neuromodulator release or uptake, and (d) changes in neuro-plasticity or neurogenesis of brain tissue.


In some embodiments, electrical neurostimulation may be provided by implanting an electrical device underneath the skin of a patient and delivering an electrical signal to a nerve such as a cranial nerve. In one embodiment, the electrical neurostimulation involves sensing or detecting a body parameter, with the electrical signal being delivered in response to the sensed body parameter. This type of stimulation is generally referred to as “active,” “feedback,” or “triggered” stimulation. In another embodiment, the system may operate without sensing or detecting a body parameter once the patient has been diagnosed with a medical condition that may be treated by neurostimulation. In this case, the system may apply a series of electrical pulses to the nerve (e.g., a cranial nerve such as a vagus nerve) periodically, intermittently, or continuously throughout the day, or over another predetermined time interval. This type of stimulation is generally referred to as “passive,” “non-feedback,” or “prophylactic,” stimulation. In yet another type of stimulation, both passive stimulation and feedback stimulation may be combined, in which electrical signals are delivered passively according to a predetermined duty cycle, and also in response to a sensed body parameter indicating a need for therapy. The electrical signal may be applied by a pulse generator that is implanted within the patient's body. In another alternative embodiment, the signal may be generated by an external pulse generator outside the patient's body, coupled by an RF or wireless link to an implanted electrode or an external transcutaneous neurostimulator (TNS).


Generally, neurostimulation signals that perform neuromodulation are delivered by the IMD via one (i.e., unipolar) or more (i.e., bipolar) leads. The leads generally terminate at their distal ends in one or more electrodes, and the electrodes, in turn, are electrically coupled to tissue in the patient's body. For example, a number of electrodes may be attached to various points of a nerve or other tissue inside or outside a human body for delivery of a neurostimulation signal.


Conventional vagus nerve stimulation (VNS) usually involves non-feedback stimulation characterized by a number of parameters. Specifically, conventional vagus nerve stimulation usually involves a series of electrical pulses in bursts defined by an “on-time” and an “off-time.” During the on-time, electrical pulses of a defined electrical current (e.g., 0.5-2.0 milliamps) and pulse width (e.g., 0.25-1.0 milliseconds) are delivered at a defined frequency (e.g., 20-30 Hz) for the on-time duration, usually a specific number of seconds, e.g., 7-60 seconds. The pulse bursts are separated from one another by the off-time, (e.g., 14 seconds-5 minutes) in which no electrical signal is applied to the nerve. The on-time and off-time parameters together define a duty cycle, which is the ratio of the on-time to the sum of the on-time and off-time, and which describes the percentage of time that the electrical signal is applied to the nerve. It will be appreciated that calculation of duty cycle should also include any ramp-up and/or ramp-down time.


In conventional VNS, the on-time and off-time may be programmed to define an intermittent pattern in which a repeating series of electrical pulse bursts are generated and applied to the vagus nerve 127. Each sequence of pulses during an on-time may be referred to as a “pulse burst.” The burst is followed by the off-time period in which no signals are applied to the nerve. The off-time is provided to allow the nerve to recover from the stimulation of the pulse burst, and to conserve power. If the off-time is set at zero, the electrical signal in conventional VNS may provide continuous stimulation to the vagus nerve. Alternatively, the idle time may be as long as one day or more, in which case the pulse bursts are provided only once per day or at even longer intervals. Typically, however, the ratio of “off-time” to “on-time” may range from about 0.5 to about 10.


Although neurostimulation has proven effective in the treatment of a number of medical conditions, including epilepsy, it would be desirable to further enhance and optimize a therapeutic regimen comprising neurostimulation for this purpose. For example, it may be desirable to provide an active therapeutic regimen at times when an unstable brain state occurs. (An “unstable brain state” will be defined below). It may also be desirable to declare an unstable brain state as occurring, based on data routinely collected from extracranial sources. It may further be desirable to adjust the sensitivity of declaring when an unstable brain state occurs, to make a declaration of an unstable brain state more or less likely for different patients, for the same patient at different times of day, month, or year, or under other conditions.


SUMMARY OF THE INVENTION

In one embodiment, the present invention relates to an implantable medical device (IMD) to treat a medical condition in a patient, comprising an electrical signal generator; at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; a cardiac data sensing module capable of sensing cardiac data from the patient; an unstable brain state declaration module comprising a cardiac module capable of determining at least a first cardiac parameter based upon sensed cardiac data from the patient; and a value setting module for setting at least a first value to be used by the unstable brain state declaration module; wherein the unstable brain state declaration module is capable of declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value and the value setting module is capable of adjusting said at least a first value.


In one embodiment, the present invention relates to a method of treating a medical condition in a patient using an implantable medical device, comprising providing an electrical signal generator; providing at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting said at least a first value.


In one embodiment, the present invention relates to a computer readable program storage device encoded with instructions that, when executed by a computer, performs a method of treating a medical condition in a patient using an implantable medical device, comprising providing an electrical signal generator; providing at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting said at least a first value.





BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:



FIGS. 1A-1C provide stylized diagrams of an implantable medical device implanted into a patient's body for providing an electrical signal to a portion of the patient's body, in accordance with one illustrative embodiment of the present invention;



FIG. 2 illustrates a block diagram depiction of the implantable medical device of FIG. 1, in accordance with one illustrative embodiment of the present invention;



FIG. 3 illustrates an exemplary waveform sequence of a cardiac cycle of a human being as measured by an electrocardiogram (EKG);



FIG. 4 illustrates a flowchart depiction of a method in accordance with an illustrative embodiment of the present invention; and



FIG. 5 illustrates a flowchart depiction of further steps of a method in accordance with an illustrative embodiment of the present invention.





While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.


DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments of the invention are described herein. In the interest of clarity, not all features of an actual implementation are described in this specification. In the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the design-specific goals, which will vary from one implementation to another. It will be appreciated that such a development effort, while possibly complex and time-consuming, would nevertheless be a routine undertaking for persons of ordinary skill in the art having the benefit of this disclosure.


This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “includes” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” Also, the term “couple” or “couples” is intended to mean either a direct or an indirect electrical connection. “Direct contact,” “direct attachment,” or providing a “direct coupling” indicates that a surface of a first element contacts the surface of a second element with no substantial attenuating medium there between. The presence of small quantities of substances, such as bodily fluids, that do not substantially attenuate electrical connections does not vitiate direct contact. The word “or” is used in the inclusive sense (i.e., “and/or”) unless a specific use to the contrary is explicitly stated.


The term “electrode” or “electrodes” described herein may refer to one or more stimulation electrodes (i.e., electrodes for delivering an electrical signal generated by an IMD to a tissue), sensing electrodes (i.e., electrodes for sensing a physiological indication of a patient's body), and/or electrodes that are capable of delivering a stimulation signal, as well as performing a sensing function.


“Cardiac cycle” refers to one complete PQRSTU interval of the patient's heart functioning, ending with the P wave of the next succeeding cardiac cycle. “Interbeat interval” refers to the time period between a predetermined point in a first cardiac cycle of the patient and the same predetermined point in the immediately succeeding cardiac cycle of the patient, for example an R-R interval, a P-P interval, or a T-T interval. Interbeat intervals may comprise a single interval or a time-varying statistic, such as a moving average (either simple or weighted) of several consecutive intervals. “Cardiac period” is a length of time between a first point in the cardiac cycle of the patient and a second, later point. Exemplary points include a P-wave, a Q-wave, an R-wave, an S-wave, a T-wave, and a U-wave of the cardiac cycle, which can be readily identified by electrocardiography (EKG) or other techniques of monitoring the electrical activity of the heart.


Any method step referring to the storing, recalling, manipulating, or changing of data, a parameter, or a value is to be understood as referring to making physical changes in an apparatus, such as an implantable medical device or an external apparatus in communication with an implantable medical device; such method steps do not refer to any purely mental step performed in the mind of a human being.


Cranial nerve stimulation has been proposed to treat a number of medical conditions pertaining to or mediated by one or more neural structures of the body, including epilepsy and other movement disorders, depression, anxiety disorders and other neuropsychiatric disorders, dementia, head trauma and traumatic brain injury, coma, obesity, eating disorders, sleep disorders, cardiac disorders (such as congestive heart failure and atrial fibrillation), hypertension, endocrine disorders (such as diabetes and hypoglycemia), and pain syndromes (including migraine headache and fibromyalgia), among others. See, e.g., U.S. Pat. Nos. 4,867,164; 5,299,569; 5,269,303; 5,571,150; 5,215,086; 5,188,104; 5,263,480; 6,587,719; 6,609,025; 5,335,657; 6,622,041; 5,916,239; 5,707,400; 5,231,988; and 5,330,515. Despite the numerous disorders for which cranial nerve stimulation has been proposed or suggested as a treatment option, the fact that detailed neural pathways for many (if not all) cranial nerves remain relatively unknown, makes predictions of efficacy for any given disorder difficult or impossible. Moreover, even if such pathways were known, the precise stimulation parameters that would modulate particular pathways relevant to a particular disorder generally cannot be predicted.


In one embodiment, the present invention provides a method of treating a medical condition. The medical condition can be selected from the group consisting of epilepsy, neuropsychiatric disorders (including but not limited to depression), eating disorders/obesity, traumatic brain injury/coma, addiction disorders, dementia, sleep disorders, pain, migraine, fibromyalgia, endocrine/pancreatic disorders (including but not limited to diabetes), motility disorders, hypertension, congestive heart failure/cardiac capillary growth, hearing disorders, angina, syncope, vocal cord disorders, thyroid disorders, pulmonary disorders, and reproductive endocrine disorders (including infertility). In a particular embodiment, the medical condition is epilepsy.


The implantable medical device (IMD) system of one embodiment of the present invention provides for module(s) that are capable of acquiring, storing, and processing one or more of various forms of data, such as patient cardiac data or a cardiac parameter (e.g., heart rate, rate of change of heart rate, etc.), at least one value used to declare an unstable brain state of a patient, declarations of unstable brain states, logs of timestamped cardiac data, cardiac parameters, and therapy parameters. Therapy parameters may include, but are not limited to, electrical signal parameters that define the therapeutic electrical signals delivered by the IMD, medication parameters, and/or any other therapeutic treatment parameter. Therapy parameters defining a therapeutic electrical signal may also include, but are not limited to, a current amplitude, a pulse width, an interburst period, a number of pulses per burst, an interpulse interval, a burst duration, an on-time, and an off-time. “Therapy parameters” encompasses one or multiple treatment regimens (e.g., different electrical signals), wherein the multiple treatment regimens may differ in one or more therapy parameters.


Although not so limited, a system capable of implementing embodiments of the present invention is described below. FIG. 1 depicts a stylized implantable medical system (IMD) 100 for implementing one or more embodiments of the present invention. An electrical signal generator 110 is provided, having a main body 112 comprising a case or shell with a header 116 for connecting to an insulated, electrically conductive lead assembly 122. The generator 110 is implanted in the patient's chest in a pocket or cavity 145 formed by the implanting surgeon just below the skin, similar to the implantation procedure for a pacemaker pulse generator.


A nerve electrode assembly 125, preferably comprising a plurality of electrodes having at least an electrode pair, is conductively connected to the distal end of the lead assembly 122, which preferably comprises a plurality of lead wires (one wire for each electrode). Each electrode in the electrode assembly 125 may operate independently or alternatively, may operate in conjunction with the other electrodes. In one embodiment, the electrode assembly 125 comprises at least a cathode and an anode. In another embodiment, the electrode assembly comprises one or more unipolar electrodes with the return electrode comprising a portion of the generator 110.


Lead assembly 122 is attached at its proximal end to connectors on the header 116 of generator 110. The electrode assembly 125 may be surgically coupled to the vagus nerve 127 in the patient's neck or at another location, e.g., near the patient's diaphragm or at the esophagus/stomach junction. Other (or additional) cranial nerves such as the trigeminal and/or glossopharyngeal nerves may also be used as a target for the electrical signal in particular alternative embodiments. In one embodiment, the electrode assembly 125 comprises a bipolar stimulating electrode pair 125-1, 125-2 (i.e., a cathode and an anode). Suitable electrode assemblies are available from Cyberonics, Inc., Houston, Tex., USA as the Model 302 electrode assembly. However, persons of skill in the art will appreciate that many electrode designs could be used in the present invention. In one embodiment, the two electrodes are wrapped about the vagus nerve, and the electrode assembly 125 may be secured to the vagus nerve 127 by a spiral anchoring tether 128 such as that disclosed in U.S. Pat. No. 4,979,511 issued Dec. 25, 1990 to Reese S. Terry, Jr. and assigned to the same assignee as the instant application. Lead assembly 122 may be secured, while retaining the ability to flex with movement of the chest and neck, by a suture connection 130 to nearby tissue (not shown).


In alternative embodiments, the electrode assembly 125 may comprise a cardiac data sensor element. Alternatively, a cardiac data sensor element may be contained in a separate sensing electrode assembly (not shown). One or more other sensor elements for other body parameters may also be included in the electrode assembly 125 or in a separate sensing electrode assembly (not shown). For example, motion sensors or electrodes may be used to sense respiration, and pressure sensors or neural activity may be used to sense blood pressure. Both passive and active stimulation may be combined or delivered by a single IMD according to the present invention. Either or both modes may be appropriate to treat a specific patient under observation.


The electrical pulse generator 110 may be programmed with an external device (ED) such as computer 150 using programming software known in the art. A programming wand 155 may be coupled to the computer 150 as part of the ED to facilitate radio frequency (RF) communication between the computer 150 and the pulse generator 110. The programming wand 155 and computer 150 permit non-invasive communication with the generator 110 after the latter is implanted. In systems where the computer 150 uses one or more channels in the Medical Implant Communications Service (MICS) bandwidths, the programming wand 155 may be omitted to permit more convenient communication directly between the computer 150 and the pulse generator 110.


The therapeutic electrical stimulation signal described herein may be used to treat a medical condition separately or in combination with another type of treatment. For example, electrical signals according to the present invention may be applied in combination with a chemical agent, such as various drugs, to treat various medical conditions. Further, the electrical stimulation may be performed in combination with treatment(s) relating to a biological or chemical agent. The electrical stimulation treatment may also be performed in combination with other types of treatment, such as magnetic stimulation treatment.


Turning now to FIG. 2, a block diagram depiction of the IMD 200 is provided, in accordance with one illustrative embodiment of the present invention. The IMD 200 (which may be equivalent to generator 110 from FIG. 1) may comprise a controller 210 capable of controlling various aspects of the operation of the IMD 200. The controller 210 is capable of receiving internal data or external data and causing a stimulation unit 220 to generate and deliver an electrical signal to target tissues of the patient's body for treating a medical condition. For example, the controller 210 may receive manual instructions from an operator externally, or may cause the electrical signal to be generated and delivered based on internal calculations and programming. The controller 210 is capable of affecting substantially all functions of the IMD 200.


The controller 210 may comprise various components, such as a processor 215, a memory 217, etc. The processor 215 may comprise one or more microcontrollers, microprocessors, etc., capable of performing various executions of software components. The memory 217 may comprise various memory portions where a number of types of data (e.g., internal data, external data instructions, software codes, status data, diagnostic data, etc.) may be stored. The memory 217 may comprise one or more of random access memory (RAM), dynamic random access memory (DRAM), electrically erasable programmable read-only memory (EEPROM), flash memory, etc.


The IMD 200 may also comprise a stimulation unit 220 capable of generating and delivering electrical signals to one or more electrodes via leads. A lead assembly such as lead assembly 122 (FIG. 1) may be coupled to the IMD 200. Therapy may be delivered to the leads comprising the lead assembly 122 by the stimulation unit 220 based upon instructions from the controller 210. The stimulation unit 220 may comprise various circuitry, such as electrical signal generators, impedance control circuitry to control the impedance “seen” by the leads, and other circuitry that receives instructions relating to the delivery of the electrical signal to tissue. The stimulation unit 220 is capable of delivering an electrical signal over the leads comprising the lead assembly 122. It will be appreciated by persons of skill in the art that some embodiments of the invention may comprise leadless stimulators such as injectable microstimulators.


The IMD 200 may also comprise a power supply 230. The power supply 230 may comprise a battery, voltage regulators, capacitors, etc., to provide power for the operation of the IMD 200, including delivering the therapeutic electrical signal. The power supply 230 comprises a power source that in some embodiments may be rechargeable. In other embodiments, a non-rechargeable power source may be used. The power supply 230 provides power for the operation of the IMD 200, including electronic operations and the electrical signal generation and delivery functions. The power supply 230 may comprise a lithium/thionyl chloride cell or a lithium/carbon monofluoride (LiCFx) cell. Other battery types known in the art of implantable medical devices may also be used.


The IMD 200 may also comprise a communication unit 260 capable of facilitating communications between the IMD 200 and various devices. In particular, the communication unit 260 is capable of providing transmission and reception of electronic signals to and from an external unit 270, such as computer 150 and wand 155 that may comprise an ED (FIG. 1). The communication unit 260 may include hardware, software, firmware, or any combination thereof.


In one embodiment, the IMD 200 may also comprise a sensor 295 that is capable of detecting various patient parameters. For example, the sensor 295 may comprise hardware, software, firmware, or any combination thereof that is capable of obtaining and/or analyzing data relating to one or more physiological parameters of the patient, such as at least one cardiac parameter. In one embodiment, the lead assembly 122 and electrode(s) 125 may function as the sensor 295. In another embodiment, the sensor 295 is a separate structure from the lead assembly 122 and electrode(s) 125. In one embodiment, the sensor 295 may reside external to the IMD 200 and the sensed results may be delivered to the IMD 200 via wire, telemetry, or other techniques known in the art. Based upon the data obtained by the sensor 295, an cardiac module 296 may determine the at least one cardiac parameter.


In one embodiment, the sensor 295 may be capable of detecting a feedback response from the patient. The feedback response may include a magnetic signal input, a tap input, a wireless data input to the IMD 200, etc. The feedback may be indicative of a pain and/or noxious threshold, wherein the threshold may be the limit of tolerance of discomfort for a particular patient.


In one embodiment, the sensor 295 may be capable of sensing cardiac data and the cardiac module 296 may be capable of determining at least one cardiac parameter of the patient from the sensed cardiac data. However, in another embodiment, a separate sensor 295 is not included, and sensing cardiac data of the patient may be performed via one or more of the electrodes 125(1), 125(2) and/or the shell 112 of the IMD 200.


Cardiac data may be sensed at any point in the patient's cardiac cycle. FIG. 3 shows an exemplary instance of the cardiac cycle in a human being.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of an interbeat interval. The cardiac module 296 may further be capable of determining a first cardiac parameter consisting of an instantaneous heart rate, that is, the reciprocal of a single interbeat interval, which may be normalized to a unit time, such as one minute. For example, if the interbeat interval is determined as an R-R interval, and a single R-R interval is 800 msec, the reciprocal is 0.00125 msec-1, or 1.25 sec-1, or 75 min-1 (75 BPM).


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a moving average heart rate over a predetermined time period. The moving average heart rate may be a simple moving average, that is, the average of the reciprocal of n consecutive interbeat intervals, wherein n is an integer from 2 to about 20, such as 3 to 10.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a rate of change of the patient's heart rate, which may be determined from a series of values of either an instantaneous heart rate or a moving average heart rate.


The cardiac module 296 may be capable of determining an elevation of a patient's heart rate above the patient's baseline heart rate. For example, a baseline heart rate may be defined as a 30-beat moving average heart rate, or longer moving average such as a 5 minute average heart rate, and the elevation may be the difference between an instantaneous heart rate and the baseline rate. Cardiac module 296 may further be capable of determining a difference between a first moving average and a second moving average. The first and second moving averages may be based upon a particular number of beats, for example a 3 beat moving average and a 30 beat moving average, or upon particular time periods, for example a 10 second moving average and a 5 minute moving average. In another embodiment, cardiac module 296 may be capable of determining a first cardiac parameter consisting of a duration of an elevation of the patient's heart rate above the patient's baseline heart rate. The patient's baseline heart rate may be determined by a medical professional at an initial calibration or subsequent recalibration of the IMD 200 or may be determined by the IMD 200 itself, such as a long term moving average of the heart rate. The long term moving average can be calculated with the exclusion of cardiac data from times recognized, either at the time or retrospectively, as being associated with an unstable brain state. “Unstable brain state” will be discussed below.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a depression of the patient's heart rate below the patient's baseline heart rate.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a duration of an elevation of a first moving average heart rate over a second moving average heart rate.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of an R-R interval.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a PR segment interval.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a PQ segment interval.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a QRS interval.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of an ST segment interval.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a statistical analysis heart parameter, such as a median, a standard deviation, or another statistical analysis value known to the person of ordinary skill in the art to be extractable or calculable from a stream of cardiac data.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of the amplitude or magnitude of the P wave, Q wave, R wave, S wave, T wave, U wave, or any segment or interval between waves; a change of the amplitude or magnitude of the wave or any segment or interval between waves; or a rate of change of the amplitude or magnitude of the wave or any segment or interval between waves. The amplitude or magnitude of a segment or interval encompasses the absolute difference in amplitude or magnitude of the waves defining the endpoints of the segment or interval and the relative difference in amplitude or magnitude of the waves defining the endpoints of the segment or interval, among other parameters.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a spectral analysis heart parameter.


The cardiac module 296 may be capable of determining a first cardiac parameter consisting of a fractal analysis heart parameter.


In one embodiment, at least a first cardiac parameter is selected from the group consisting of an instantaneous heart rate, a moving average heart rate over a predetermined time period, a ratio of a first moving average heart rate over a first predetermined time period and a second moving average heart rate over a second predetermined time period, a rate of change of the patient's heart rate, an elevation of the patient's instantaneous heart rate above a baseline heart rate, a duration of an elevation of the patient's heart rate above the patient's baseline heart rate, a depression of the patient's heart rate below the patient's baseline heart rate, a duration of an elevation of a first moving average heart rate over a second moving average heart rate, an R-R interval, a PR segment interval, a PQ segment interval, a QRS interval, an ST segment interval, a QT interval, a statistical analysis heart parameter, a spectral analysis heart parameter, a fractal analysis heart parameter, an interbeat interval, the amplitude or magnitude of the P wave, Q wave, R wave, S wave, T wave, U wave, or any segment or interval between waves; a change of the amplitude or magnitude of the wave or any segment or interval between waves; or a rate of change of the amplitude or magnitude of the wave or any segment or interval between waves, and two or more thereof.


The external unit 270 may be a device that is capable of programming the IMD 200 with parameters defining the electrical signal. In one embodiment, the external unit 270 is a computer system capable of executing a data-acquisition program. The external unit 270 may be controlled by a healthcare provider, such as a physician, at a base station in, for example, a doctor's office, or via telemetry from a doctor's office to a patient's home. In alternative embodiments, the external unit 270 may be controlled by a patient in a system. In patient-controlled systems, the external unit 270 may provide less control over the operation of the IMD 200 than another external unit 270 controlled by a healthcare provider. Whether controlled by the patient or by a healthcare provider, the external unit 270 may be a computer, preferably a handheld computer or PDA, but may alternatively comprise any other device that is capable of electronic communications and programming, e.g., hand-held computer system, a PC computer system, a laptop computer system, a server, a personal digital assistant (PDA), an Apple-based computer system, etc. The external unit 270 may upload various parameters and program software into the IMD 200 for programming the operation of the IMD, and may also receive and download various status conditions and other data from the IMD 200. Communications between the external unit 270 and the communication unit 260 in the IMD 200 may occur via a wireless or other type of communication, represented generally by line 277 in FIG. 2. This may occur using, e.g., wand 155 (FIG. 1) to communicate by RF energy with a generator 110. Alternatively, the wand may be omitted in some systems, e.g., systems in which external unit 270 operates in the MICS bandwidths.


In one embodiment, the external unit 270 may comprise a local database unit 255. Optionally or alternatively, the external unit 270 may also be coupled to a database unit 250, which may be separate from external unit 270 (e.g., a centralized database wirelessly linked to a handheld external unit 270). The database unit 250 and/or the local database unit 255 are capable of storing various data. This data may comprise cardiac data acquired from a patient's body, at least one cardiac parameter derived from the cardiac data, other data acquired from a patient's body, at least one non-cardiac parameter derived from the other data, at least a first value as will be discussed below, and/or therapy parameter data. The database unit 250 and/or the local database unit 255 may comprise data for a plurality of patients, and may be organized and stored in a variety of manners, such as in date format, severity of disease format, etc. The database unit 250 and/or the local database unit 255 may be relational databases in one embodiment. A physician may perform various patient management functions using the external unit 270, which may include obtaining and/or analyzing data from the IMD 200 and/or data from the database unit 250 and/or the local database unit 255. The database unit 250 and/or the local database unit 255 may store various patient data.


One or more of the blocks illustrated in the block diagram of the IMD 200 in FIG. 2 may comprise hardware units, software units, firmware units, or any combination thereof. Additionally, one or more blocks illustrated in FIG. 2 may be combined with other blocks, which may represent circuit hardware units, software algorithms, etc. Additionally, any number of the circuitry or software units associated with the various blocks illustrated in FIG. 2 may be combined into a programmable device, such as a field programmable gate array, an ASIC device, etc.


Pulse shapes in electrical signals according to the present invention may include a variety of shapes known in the art including square waves, biphasic pulses (including active and passive charge-balanced biphasic pulses), triphasic waveforms, etc. In one embodiment, the pulses comprise a square, biphasic waveform in which the second phase is a charge-balancing phase of the opposite polarity to the first phase.


Patient activation of an IMD 100 may involve use of an external control magnet for operating a reed switch in an implanted device, for example. Certain other techniques of manual and automatic activation of implantable medical devices are disclosed in U.S. Pat. No. 5,304,206 to Baker, Jr., et al., assigned to the same assignee as the present application (“the '206 patent”). According to the '206 patent, means for manually activating or deactivating the electrical signal generator 110 may include a sensor such as piezoelectric element mounted to the inner surface of the generator case and adapted to detect light taps by the patient on the implant site. One or more taps applied in fast sequence to the skin above the location of the electrical signal generator 110 in the patient's body may be programmed into the implanted medical device 100 as a signal for activation of the electrical signal generator 110. Two taps spaced apart by a slightly longer duration of time may be programmed into the IMD 100 to indicate a desire to deactivate the electrical signal generator 110, for example. The patient may be given limited control over operation of the device to an extent determined by the program dictated or entered by the attending physician. The patient may also activate the IMD 100 using other suitable techniques or apparatus.


In one embodiment, the present invention relates to an implantable medical device (IMD) to treat a medical condition in a patient, comprising an electrical signal generator 220; at least a first electrode 125-1 operatively coupled to the electrical signal generator and to a vagus nerve 127 of the patient; a cardiac data sensing module 295 capable of sensing cardiac data from the patient; an unstable brain state declaration module 280 comprising a cardiac module 296 capable of determining at least a first cardiac parameter based upon sensed cardiac data from the patient; and a value setting module 282 for setting at least a first value to be used by the unstable brain state declaration module 280; wherein the unstable brain state declaration module 280 is capable of declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value and the value setting module 282 is capable of adjusting said at least a first value.


The electrical signal generator 220 has been described above, as has the at least a first electrode 125-1 operatively coupled to the electrical signal generator 220 and to a vagus nerve 127 of the patient and the cardiac data sensing module 295 capable of sensing cardiac data from the patient.


The IMD 200 comprises an unstable brain state declaration module 280 that, in turn, comprises a cardiac module 296 capable of determining at least a first cardiac parameter based upon sensed cardiac data from the patient. IMD 200 further comprises a value setting module 282 for setting at least a first value to be used by the unstable brain state declaration module 280. The unstable brain state declaration module 280 is capable of declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value.


An “unstable brain state” is used herein to refer to the state of the brain during an epileptic seizure, the state of the brain during an aura, the state of the brain during a post-ictal period after an epileptic seizure, or any other state of the brain associated with the increased likelihood of a seizure in the near future (within from about 1 sec to about 12 hr, such as from about 5 sec to about 1 hr, such as from about 10 sec to about 5 min). An unstable brain state may be attested by a somatic indication of an epileptic seizure, aura, or other unstable brain state, but need not be. An unstable brain state may be attested by an electroencephalographic (EEG) indication of an epileptic seizure, aura, or other unstable brain state, but need not be. An unstable brain state encompasses both a state after which an epileptic seizure is highly likely or even inevitable, as well as a state in which an otherwise highly likely or inevitable epileptic seizure can be prevented by the application of a therapeutic electrical signal to nervous tissue, such as the brain or a cranial or peripheral nerve. However, an unstable brain state may be declared with a reasonable degree of accuracy from somatic indications, and in a particular embodiment, from at least one cardiac parameter, in light of at least a first value.


The cardiac module 296 is capable of determining at least a first cardiac parameter based upon sensed cardiac data from the patient, as discussed above.


The value setting module 282 sets at least a first value to be used by the unstable brain state declaration module 280. The at least a first value, along with the at least a first cardiac parameter determined by the cardiac module 296, is used by the unstable brain state declaration module 280 to declare or not declare the occurrence of an unstable brain state. For example, the at least a first cardiac parameter may be a moving average of the patient's heart rate (by way of example only, having a baseline value of 60-75 BPM) and the at least a first value may be a heart rate threshold value (by way of example only, 120 BPM). At a predetermined sampling rate, by way of example, from about 100 times per second to about once per five seconds, the cardiac module 296 determines the moving average of the patient's heart rate and the unstable brain state declaration module 280 compares the moving average of the patient's heart rate to the heart rate threshold value. If, by way of example only, the moving average of the patient's heart rate is 125 BPM, which is greater than the heart rate threshold value of this example, the unstable brain state declaration module 280 declares that an unstable brain state has occurred. If, by way of example only, the moving average of the patient's heart rate is 80 BPM, which is less than the heart rate threshold value of this example, the unstable brain state declaration module 280 does not declare an unstable brain state to have occurred.


In one embodiment, the memory 217 is capable of storing a timestamp associated with a declaration of an unstable brain state by the unstable brain state declaration module 280. The memory 217 may also be capable of storing a time series of the at least one cardiac parameter and/or the at least a first value. The unstable brain state declaration module 280, or another module in the IMD 200 or in an apparatus in communication with the IMD 200 (such as the computer 150), may create a log of times at which a patient experiences an unstable brain state.


In addition to the heart rate threshold value discussed above, the at least a first value may also comprise a minimum duration of an elevation of heart rate, a threshold rate of change of heart rate, or any combination of cardiac and/or non-cardiac values. The at least a first value may be a logical or Boolean value, a set of logical or Boolean values, or a combination of one or more logical or Boolean values and one or more alphanumeric values. In embodiments in which the IMD 200 collects multiple parameters, such as multiple cardiac parameters, or both at least one cardiac parameter and at least one non-cardiac parameter (discussed below), the at least a first value may also comprise either or both of weightings for each of the multiple parameters, and logical relationships between each of the multiple parameters.


The value setting module 282 is capable of adjusting the at least first value. The determination of the different value may be made by a medical professional, by the patient, or by the IMD 200 itself. For example, continuing the above example, if the patient experienced a seizure correlated with an increase in the patient's heart rate to 115 BPM (below the heart rate threshold value of 120 BPM, and hence, with no declaration of an unstable brain state), the value setting module 282 may adjust the heart rate threshold value to 115 BPM, 110 BPM, or some other value. Such adjustment would render the unstable brain state determination module more likely to declare an unstable brain state.


Alternatively in the above example, if the patient experienced a heart rate above the heart rate threshold value of 120 BPM, and hence, an unstable brain state was declared, but the patient's elevated heart rate was caused by volitional physical exertion, an intense emotional response, or another cause not associated with an unstable brain state, the value setting module 282 may adjust the heart rate threshold value to 125 BPM, 130 BPM, or some other value. Such adjustment would render the unstable brain state determination module less likely to declare an unstable brain state.


Continuing with the above example, the decision to adjust the heart rate threshold may be made by a medical professional or by the patient, such as at a time shortly after the seizure or at a later time when a log of the patient's at least one cardiac parameter is analyzed. In other words, in this embodiment, the value setting module 282 is capable of adjusting the at least a first value in response to a user request to adjust the at least a first value.


The present invention gives a user, such as a patient or a medical professional, great flexibility in deciding how to respond to uncertainty inherent in the assessment of whether or not an unstable brain state has occurred. A user may set the at least a first value such that the unstable brain state declaration module 280 declares unstable brain states with any desired level of aggressiveness or certainty. For example, a user may accept a high “false positive” rate and want the unstable brain state declaration module 280 to declare every putative unstable brain state; contrarily, a user may desire a low “false positive” rate and want the unstable brain state declaration module 280 to only declare an unstable brain state with very high certainty, or even to declare only particular kinds of unstable brain states, such as relatively severe epileptic seizures as opposed to all seizures. Thus, the present invention provides the user a great deal of flexible control over the stringency of declarations of unstable brain states.


Having the benefit of the present disclosure, the person of ordinary skill in the art would be able to set and adjust the at least a first value as a matter of routine experimentation.


In one embodiment, the adjustment may be made by a unit of the value setting module 282 on a determination of an unstable brain state from other data, such as other cardiac data (e.g., an elevation of heart rate above the patient's baseline heart rate for a predetermined or adjustable duration, or a difference between a first moving average and a second moving average, among others) or other data (e.g., an output from an accelerometer measuring acceleration of the patient's limbs, torso, or head, wherein the output is indicative of a seizure; or an output from electromyography of one or more muscles, wherein the output is indicative of a seizure; among others).


As discussed above, the value setting module 282 is capable of adjusting the at least a first value to render the unstable brain state declaration module 280 less likely to declare an unstable brain state. Rendering the unstable brain state declaration module 280 less likely to declare an unstable brain state may lead to fewer overall declarations of unstable brain states or a delay in a declaration of an unstable brain state, among other possible outcomes. This may be desirable, for example, when a healthcare provider desires to use the IMD as a seizure diary and wishes to avoid declaring an unstable brain state unless and until an epileptic seizure actually occurs, or when the device responds to the declaration of an unstable brain state by providing vagus nerve stimulation, but the patient has difficulty tolerating the therapy thus provided. Adjusting the first value to reduce the likelihood of a declaration of an unstable brain state may lead to fewer false declarations of unstable brain states. Such an adjustment may, however, risk actual occurrences of unstable brain states that are not declared, i.e., may lead to more “false negatives,” with an associated increased risk that an epileptic seizure would occur without therapy being administered or being administered late.


As stated above, rendering the unstable brain state declaration module 280 less likely to declare an unstable brain state may in some embodiments lead to a delay in a declaration of an unstable brain state. A delay in declaration may be advantageous by giving greater certainty to the patient or physician that a declaration is made when an unstable brain state is actually occurring. However, this does represent a trade-off against earlier declaration of an unstable brain state. For example, if the declaration of an unstable brain state is followed by a therapeutic electrical signal intended to intervene in the unstable brain state, a delay in declaration may lead to a shorter time window for delivering the therapeutic electrical signal or a requirement for the therapeutic electrical signal to have a higher amplitude, frequency, on-time, or other parameter than would be required if the therapy were provided sooner.


Similarly, as discussed above, the value setting module 282 is capable of adjusting the at least a first value to render the unstable brain state declaration module 280 more likely to declare an unstable brain state. Rendering the unstable brain state declaration module 280 more likely to declare an unstable brain state may lead to more overall declarations of unstable brain states or faster declaration of an unstable brain state, among other possible outcomes. Such an adjustment may be desirable where a patient experiences severe epileptic seizures, and it is important to intervene with a therapy such as vagus nerve stimulation as early as possible with the goal of avoiding or reducing the severity of the seizure, even if some occasions of “false positives” occur in which a seizure would not have occurred even absent the therapy intervention. Adjusting the first value to increase the likelihood of a declaration of the occurrence of an unstable brain state may lead to fewer unstable brain states actually leading to seizures, though one or more false declarations of unstable brain states may result, along with an increase in unnecessary therapy interventions.


As should be apparent to the person of ordinary skill in the art, rendering the unstable brain state declaration module 280 more likely to declare an unstable brain state may lead to a faster declaration of an unstable brain state. A faster declaration may be advantageous by giving a longer time window for delivering a therapeutic electrical signal or by allowing the therapeutic electrical signal to have a lower amplitude, frequency, on-time, or other parameter than if the therapy were provided later. However, this does represent a trade-off against later declaration of an unstable brain state. For example, faster declaration of an unstable brain state may reduce the certainty to the patient or physician that a declaration is made when an unstable brain state is actually occurring.


Alternatively or in addition to use of at least one cardiac parameter and at least a first value to declare an unstable brain state, in one embodiment, the unstable brain state declaration module 280 may determine at least one non-cardiac parameter and at least a second value. The at least one non-cardiac parameter and at least a second value may either be used in a calculation to confirm or deny a declaration of an unstable brain state based on the at least one cardiac parameter and the at least a first value, or may be used in combination with the at least one cardiac parameter and the at least a first value in making the declaration of an unstable brain state. Alternatively or in addition, the at least one non-cardiac parameter and at least a second value may be used to make a “shadow” or putative declaration of an unstable brain state, against which declarations of unstable brain states using the at least one cardiac parameter can be compared by a medical professional or the IMD to assist in adjusting the at least a first value. Returning to the above example, wherein the at least a first value is a heart rate threshold value, the “shadow” declaration of an unstable brain state can be the basis for a decision to raise or lower the heart rate threshold value.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module (not shown) capable of detecting an activity level of the patient.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting an output of an accelerometer. The accelerometer may be worn on the patient's person or implanted in the patient's body.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting a catamenial cycle. The parameter detection module of this embodiment may detect the presence of hormones associated with the catamenial cycle, the patient's basal temperature, the patient's or her physician's observation of events indicative of various points in her catamenial cycle, or other data indicative of the patient's catamenial cycle.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting the time of day. The parameter detection module of this embodiment may be a clock or a module capable of querying a clock for the current time.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting an indicator of the patient's sleep state. Exemplary indicators of the patient's sleep include electroencephalogram (EEG) signals associated with sleep and rapid eye movements associated with REM sleep, among others.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting an inclination of the patient's body.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting a dilation of a pupil of the patient.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting the patient's body temperature.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting the patient's blood pressure.


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting the patient's electroencephalogram (EEG).


In one embodiment, the unstable brain state declaration module 280 may further comprise a non-cardiac parameter detection module capable of detecting at least one non-cardiac parameter selected from the group consisting of an activity level of the patient, an output of an accelerometer, a catamenial cycle, the time of day, an indicator of the patient's sleep state, an inclination of the patient's body, a dilation of a pupil of the patient, the patient's body temperature, the patient's blood pressure, and the patient's electroencephalogram (EEG).


As stated above, in embodiments wherein the unstable brain state declaration module 280 uses multiple parameters, the at least a first value may relate to weightings of or logical relationships between the multiple parameters. For example, if an accelerometer (A) has been inactive and heart rate (R) begins to increase rapidly, the at least a first value may be a logical value boolHeartRateIncreaseWithoutActivity set to true, and the unstable brain state declaration module 280 may declare an unstable brain state from the logical value being true. However if an accelerometer indicates high activity level and then heart rate begins to increase rapidly, a logical value boolHeartRateIncreaseWithoutActivity may be set to false, and the unstable brain state declaration module 280 may not declare an unstable brain state from the logical value being false. More aggressive users may desire a logical value boolHeartRateIncrease=true or one of a pair of logical values (boolHeartRateIncrease=true or boolActivity=true) to be sufficient for the unstable brain state declaration module 280 to declare an unstable brain state.


In embodiments wherein the unstable brain state declaration module 280 further comprises a non-cardiac parameter detection module, the value setting module 282 may be capable of setting at least a second value, and the unstable brain state declaration module 280 is capable of declaring an unstable brain state of the patient from both said at least one non-cardiac parameter and said at least a second value. For example, the second value may be an acceleration threshold of a limb; if an accelerometer implanted in the limb reports an acceleration greater than the acceleration threshold, the unstable brain state declaration module 280 in this example may declare an unstable brain state on the assumption the limb acceleration results from uncontrolled contraction of one or more skeletal muscles in the limb.


In one embodiment, the at least one non-cardiac parameter and the at least a second value can be used by the value setting module 282 to adjust the at least a first value, the at least a second value, or both. Alternatively or in addition, in embodiments wherein the memory 217 is capable of storing a timestamp at which a patient experienced an unstable brain state declared by the unstable brain state declaration module 280, the timestamp or a log of timestamps can be used by the value setting module 282 to adjust the at least a first value, the at least a second value, or both. In other words, in one embodiment the value setting module 282 is capable of adjusting the at least a first value, the at least a second value, or both based upon at least one factor selected from the group consisting of a timestamp at which a patient experienced an unstable brain state, cardiac data associated with a timestamp at which a patient experienced an unstable brain state, an activity level of the patient, an output of an accelerometer, a catamenial cycle, the time of day, an indicator of the patient's sleep, an inclination of the patient's body, a dilation of a pupil of the patient, the patient's body temperature, the patient's blood pressure, and the patient's electroencephalogram (EEG).


A patient may experience changes in the frequency of unstable brain states over various periods of time. For example, a patient may have an increased frequency of unstable brain states during certain hours of the day, certain days of the week or month, certain seasons of the year, or over longer periods of time as the patient's disease state changes. In one embodiment, the value setting module 282 is capable of analyzing a log of times at which a patient experiences an unstable brain state to determine at least a first period when the patient has an increased frequency of unstable brain states, and adjusting the at least a first value to render the unstable brain state declaration module 280 more likely to declare an unstable brain state during said at least a first period. The first period may be less than one day. In other embodiments, the first period may be less than one week, less than one month, or less than one year.


The value setting module 282 may comprise other modules than those described above.


The IMD 200 described above, and methods described herein, are useful in providing a user, such as a patient or a medical professional, with information regarding the patient's unstable brain states. Such information may assist the patient and the medical professional in improving the patient's treatment regimen or improving the patient's quality of life. The information regarding the patient's unstable brain states may include an alert to the patient and/or his caregiver that an epileptic seizure is likely, giving the patient and/or his caregiver some time to prepare for the epileptic seizure and its aftermath.


In one embodiment, the electrical signal generator of the implantable medical device is capable of generating and delivering at least a first electrical signal through at least the first electrode to the vagus nerve if an unstable brain state has not been declared, and generating and delivering at least a second electrical signal through at least the first electrode to the vagus nerve if an unstable brain state has been declared. The first electrical signal can be a conventional VNS signal for the chronic treatment of epilepsy. The second electrical signal can be an active VNS signal for the prevention or reduction in severity of an epileptic seizure. The second electrical signal can have a greater pulse amplitude, a wider pulse width, a higher pulse frequency, a greater number of pulses per burst, a higher on time/off time ratio, or two or more thereof, relative to a conventional VNS signal. Such a second electrical signal would consume more electrical power than a conventional VNS signal and could be attenuated by adaptation thereto by neurons of the vagus nerve if the second electrical signal were continuously applied. However, if the second electrical signal were applied only when an unstable brain state is declared, the duration of application would be expected to be short enough that adaptation thereto would be unlikely, and the increased consumption of electrical power would be likely to be offset by a reduction in the number, severity, or both of the patient's seizures and an accompanying improvement in the patient's quality of life. The adjustability of the at least a first value would allow considerations of IMD battery life to be included in the actions of the value setting module 282.


In one embodiment, as shown in FIG. 4, the present invention relates to a method 400 of treating a medical condition in a patient using an implantable medical device 200, comprising providing 410 an electrical signal generator; providing 420 at least a first electrode operatively coupled to the electrical signal generator and to a vagus nerve of the patient; sensing 430 cardiac data of the patient; determining 440 at least a first cardiac parameter based upon said cardiac data; setting 450 at least a first value; declaring 460 an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting 470 the at least a first value.


In one embodiment, the method can further comprise generating and applying 462 a first electrical signal to the vagus nerve if an unstable brain state has not been declared, and generating and applying 464 a second electrical signal to the vagus nerve if an unstable brain state has been declared. FIG. 5 shows this embodiment.


In one embodiment, sensing 430 cardiac data comprises sensing at least one of a P wave, an Q wave, a QR complex, an R wave, an S wave, a QRS complex, a T wave, and a U wave, and wherein said at least a first cardiac parameter comprises at least one of an instantaneous heart rate, a moving average heart rate over a predetermined time period, a ratio of a first moving average heart rate over a first predetermined time period and a second moving average heart rate over a second predetermined time period, a rate of change of the patient's heart rate, an elevation of the patient's instantaneous heart rate above a baseline heart rate, a duration of an elevation of the patient's heart rate above the patient's baseline heart rate, a duration of an elevation of a first moving average heart rate over a second moving average heart rate, an R-R interval, a P-P interval, a PR segment interval, a PQ segment interval, a QRS interval, an ST segment interval, a QT interval, a statistical analysis heart parameter, a spectral analysis heart parameter, a fractal analysis heart parameter, and two or more thereof.


In one embodiment, adjusting 470 the at least a first value occurs in response to a user request to adjust the first value.


In one embodiment, adjusting 470 the at least a first value comprises rendering declaring an unstable brain state less likely and/or less quickly. In another embodiment, adjusting 470 the at least a first value comprises rendering declaring an unstable brain state more likely and/or more quickly.


In one embodiment, the method further comprises storing a timestamp associated with declaring an unstable brain state. In one further embodiment, adjusting the at least a first value is based upon a plurality of the timestamps. In another further embodiment, the method further comprises storing a time series of the at least a first cardiac parameter.


In one embodiment, the method further comprises determining at least a first period when the patient has an increased frequency of unstable brain states, and adjusting the at least a first value to render declaring an unstable brain state more likely during said at least a first period.


In one embodiment, the present invention relates to a computer readable program storage device encoded with instructions that, when executed by a computer, performs a method of treating a medical condition in a patient using an implantable medical device, comprising; sensing cardiac data of the patient; determining at least a first cardiac parameter based upon said cardiac data; setting at least a first value; declaring an unstable brain state of a patient from said at least a first cardiac parameter and said at least a first value; and adjusting the at least a first value.


The method executed by the computer may provide a log of unstable brain states or an alert of an unstable brain state.


In one embodiment of the computer readable program storage device, the method further comprises, if an unstable brain state is not declared, instructing an electrical signal generator to generate and deliver a first electrical signal through at least the first electrode to the vagus nerve of the patient, and if an unstable brain state is declared, instructing an electrical signal generator to generate and deliver a second electrical signal through at least the first electrode to the vagus nerve of the patient.


Using embodiments of the present invention, a therapeutic regimen comprising neurostimulation may be enhanced and optimized. Using certain embodiments, data either directly or indirectly associated with an acute incident of a medical condition may be collected, in order to inform the patient and/or his physician about the severity, progression, or remission of the medical condition.


All of the methods and apparatuses disclosed and claimed herein may be made and executed without undue experimentation in light of the present disclosure. While the methods and apparatus of this invention have been described in terms of particular embodiments, it will be apparent to those skilled in the art that variations may be applied to the methods and apparatus and in the steps, or in the sequence of steps, of the method described herein without departing from the concept, spirit, and scope of the invention, as defined by the appended claims. It should be apparent that the principles of the invention may be applied to selected cranial nerves other than, or in addition to, the vagus nerve to achieve particular results in treating patients having epilepsy, depression, or other medical conditions.


The particular embodiments disclosed above are illustrative only as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown other than as described in the claims below. It is, therefore, evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.

Claims
  • 1. A medical device comprising: a cardiac data sensing module operable to sense cardiac data;a non-cardiac data sensing module operable to sense non-cardiac data;a value setting module operable to set: a first cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; anda first non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac data sensing module;a cardiac parameter detection module operable to determine a first cardiac parameter based upon sensed data from the cardiac sensing module;a non-cardiac parameter detection module operable to determine a first non-cardiac parameter based upon sensed data from the non-cardiac sensing module;an unstable brain state declaration module operable to declare a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the first non-cardiac parameter exceeds the first non-cardiac threshold value.
  • 2. The medical device of claim 1, wherein: the value setting module is further operable to set a second cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module;the cardiac parameter detection module is further operable to determine a second cardiac parameter based upon sensed data from the cardiac sensing module; andthe unstable brain state declaration module is further operable to declare a seizure when the second cardiac parameter exceeds the second cardiac threshold value.
  • 3. The medical device of claim 1, wherein: the value setting module is further operable to set a second non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac data sensing module;the non-cardiac parameter detection module is further operable to determine a second non-cardiac parameter based upon sensed data from the non-cardiac sensing module; andthe unstable brain state declaration module is further operable to declare a seizure when the second non-cardiac parameter exceeds the second non-cardiac threshold value.
  • 4. The medical device of claim 1, further comprising: a second non-cardiac data sensing module operable to sense a second non-cardiac data;the value setting module is further operable to set a second non-cardiac threshold value based upon sensed non-cardiac data from the second non-cardiac data sensing module;the non-cardiac parameter detection module is further operable to determine a second non-cardiac parameter based upon sensed data from the second non-cardiac sensing module; andthe unstable brain state declaration module operable to declare a seizure when the second non-cardiac parameter exceeds the second non-cardiac threshold value.
  • 5. The medical device of claim 1, wherein: the value setting module is further operable to apply a weighting to the first cardiac threshold value and the first non-cardiac threshold value; andthe unstable brain state declaration module is operable to utilize the weighting in declaring a seizure.
  • 6. The medical device of claim 1, wherein the value setting module is further operable to adjust a threshold value in response to a user request to adjust the threshold value.
  • 7. The medical device of claim 1, wherein the value setting module is further operable to adjust each threshold value to render the unstable brain state declaration module less likely to declare a seizure.
  • 8. The medical device of claim 1, wherein the value setting module is further operable to adjust each threshold value to render the unstable brain state declaration module more likely to declare a seizure.
  • 9. The medical device of claim 1, wherein the first cardiac parameter is selected from the group comprising: an instantaneous heart rate;a moving average heart rate over a predetermined time period;a ratio of a first moving average heart rate over a first predetermined time period and a second moving average heart rate over a second predetermined time period;a rate of change of a heart rate;an elevation of an instantaneous heart rate above a baseline heart rate;a duration of an elevation of a heart rate above a baseline heart rate;a depression of a heart rate below a baseline heart;a duration of an elevation of a first moving average heart rate over a second moving average heart rate;an R-R interval;a PR segment interval;a PQ segment interval;a QRS interval;an ST segment interval;a statistical analysis heart parameter;a spectral analysis heart parameter;a fractal analysis heart parameter;an interbeat interval;an amplitude or a magnitude of the P wave, Q wave, R wave, S wave, T wave, U wave;a change in amplitude or a magnitude of a wave; anda rate of change inn amplitude or a magnitude of a wave.
  • 10. The medical device of claim 1, wherein the first non-cardiac parameter is selected from the group comprising: an activity level;an output of an accelerometer;a catamenial cycle;a time of day;an indicator of a sleep state;an inclination of a body;a pupil dilation;a body temperature;a blood pressure; andan electroencephalogram (EEG).
  • 11. The device of claim 1, wherein the value setting module is operable to dynamically adjust the first cardiac threshold value based upon sensed cardiac data from the cardiac sensing module or the first non-cardiac threshold value based upon sensed non-cardiac data from the non-cardiac sensing module.
  • 12. The medical device of claim 1, further comprising a memory that stores a timestamp associated with a declaration of a seizure.
  • 13. The medical device of claim 12, wherein the value setting module is further configured to adjust a threshold value based upon the timestamp at which a seizure is declared.
  • 14. The medical device of claim 12, wherein the value setting module is further configured to: perform an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; andadjust the first cardiac threshold value or the first non-cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period.
  • 15. The medical device of claim 1, wherein the medical device comprises an implantable medical device (IMD).
  • 16. A medical device comprising: a cardiac data sensing module operable to sense cardiac data;a value setting module operable to set: a first cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module; anda second cardiac threshold value based upon sensed cardiac data from the cardiac data sensing module;a cardiac parameter detection module operable to determine:a first cardiac parameter based upon sensed data from the cardiac sensing module; anda second cardiac parameter based upon sensed data from the cardiac sensing module;an unstable brain state declaration module operable to declare a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the second cardiac parameter exceeds the second cardiac threshold value.
  • 17. The medical device of claim 16, wherein: the value setting module is further operable to apply a weighting to the first cardiac threshold value and the second cardiac threshold value; andthe unstable brain state declaration module is operable to utilize the weighting in declaring a seizure.
  • 18. The medical device of claim 16, further comprising a memory that stores a timestamp associated with a declaration of a seizure.
  • 19. The medical device of claim 18, wherein the value setting module is further configured to: perform an analysis of a log of times at which a seizure was declared to determine a first period when an increased frequency of seizure declarations are likely to occur; andadjust the first cardiac threshold value or second cardiac threshold value to render the unstable brain state declaration module more likely to declare a seizure during the first period.
  • 20. The medical device of claim 16, wherein the value setting module is operable to dynamically adjust the first cardiac threshold value or the second cardiac threshold value in response to sensed cardiac data from the cardiac sensing module.
  • 21. A method of declaring an unstable brain state using a medical device, comprising: sensing cardiac data;sensing non-cardiac data;setting a first cardiac threshold value based upon the sensed cardiac data;setting a first non-cardiac threshold value based upon the sensed non-cardiac data;determining a first cardiac parameter based upon the sensed cardiac data;determining a first non-cardiac parameter based upon the sensed non-cardiac data; anddeclaring a seizure when the first cardiac parameter exceeds the first cardiac threshold value or the first non-cardiac parameter exceeds the first non-cardiac threshold value.
Parent Case Info

This application is a continuation application of U.S. patent application Ser. No. 12/258,019, filed Oct. 24, 2008 and is hereby incorporated herein by reference in its entirety.

US Referenced Citations (375)
Number Name Date Kind
4172459 Hepp Oct 1979 A
4291699 Geddes et al. Sep 1981 A
4541432 Molina-Negro et al. Sep 1985 A
4573481 Bullara Mar 1986 A
4702254 Zabara Oct 1987 A
4867164 Zabara Sep 1989 A
4920979 Bullara May 1990 A
4949721 Toriu et al. Aug 1990 A
4979511 Terry, Jr. Dec 1990 A
5025807 Zabara Jun 1991 A
5113869 Nappholz et al. May 1992 A
5137020 Wayne et al. Aug 1992 A
5154172 Terry, Jr. et al. Oct 1992 A
5179950 Stanislaw Jan 1993 A
5186170 Varrichio et al. Feb 1993 A
5188104 Wernicke et al. Feb 1993 A
5203326 Collins Apr 1993 A
5205285 Baker, Jr. Apr 1993 A
5215086 Terry, Jr. et al. Jun 1993 A
5215089 Baker, Jr. Jun 1993 A
5222494 Baker, Jr. Jun 1993 A
5231988 Wernicke et al. Aug 1993 A
5235980 Varrichio et al. Aug 1993 A
5237991 Baker, Jr. et al. Aug 1993 A
5243980 Mehra Sep 1993 A
5251634 Weinberg Oct 1993 A
5263480 Wernicke et al. Nov 1993 A
5269302 Swartz et al. Dec 1993 A
5269303 Wernicke et al. Dec 1993 A
5299569 Wernicke et al. Apr 1994 A
5304206 Baker, Jr. et al. Apr 1994 A
5311876 Olsen et al. May 1994 A
5313953 Yomtov et al. May 1994 A
5330507 Schwartz Jul 1994 A
5330515 Rutecki et al. Jul 1994 A
5334221 Bardy Aug 1994 A
5335657 Terry, Jr. et al. Aug 1994 A
5404877 Nolan et al. Apr 1995 A
5425373 Causey, III Jun 1995 A
5522862 Testerman et al. Jun 1996 A
5540730 Terry, Jr. et al. Jul 1996 A
5540734 Zabara Jul 1996 A
5571150 Wernicke et al. Nov 1996 A
5611350 John Mar 1997 A
5645570 Corbucci Jul 1997 A
5651378 Matheny et al. Jul 1997 A
5658318 Stroetmann et al. Aug 1997 A
5683422 Rise et al. Nov 1997 A
5690681 Geddes et al. Nov 1997 A
5690688 Noren et al. Nov 1997 A
5700282 Zabara Dec 1997 A
5707400 Terry, Jr. et al. Jan 1998 A
5716377 Rise et al. Feb 1998 A
5720771 Snell Feb 1998 A
5743860 Hively et al. Apr 1998 A
5792186 Rise Aug 1998 A
5800474 Benabid et al. Sep 1998 A
5833709 Rise et al. Nov 1998 A
5913876 Taylor et al. Jun 1999 A
5916239 Geddes et al. Jun 1999 A
5928272 Adkins et al. Jul 1999 A
5941906 Barreras, Sr. et al. Aug 1999 A
5942979 Luppino Aug 1999 A
5978702 Ward et al. Nov 1999 A
5987352 Klein et al. Nov 1999 A
5995868 Osorio et al. Nov 1999 A
6016449 Fischell et al. Jan 2000 A
6018682 Rise Jan 2000 A
6061593 Fischell et al. May 2000 A
6073048 Kieval et al. Jun 2000 A
6083249 Familoni Jul 2000 A
6091992 Bourgeois et al. Jul 2000 A
6104956 Naritoku et al. Aug 2000 A
6115628 Stadler et al. Sep 2000 A
6115630 Stadler et al. Sep 2000 A
6128538 Fischell et al. Oct 2000 A
6134474 Fischell et al. Oct 2000 A
6167311 Rezai Dec 2000 A
6171239 Humphrey Jan 2001 B1
6175764 Loeb et al. Jan 2001 B1
6205359 Boveja Mar 2001 B1
6208894 Schulman et al. Mar 2001 B1
6208902 Boveja Mar 2001 B1
6221908 Kilgard et al. Apr 2001 B1
6248080 Miesel et al. Jun 2001 B1
6253109 Gielen Jun 2001 B1
6269270 Boveja Jul 2001 B1
6272379 Fischell et al. Aug 2001 B1
6304775 Iasemidis et al. Oct 2001 B1
6324421 Stadler et al. Nov 2001 B1
6337997 Rise Jan 2002 B1
6339725 Naritoku et al. Jan 2002 B1
6341236 Osorio et al. Jan 2002 B1
6356784 Lozano et al. Mar 2002 B1
6356788 Boveja Mar 2002 B2
6366813 DiLorenzo Apr 2002 B1
6366814 Boveja Apr 2002 B1
6374140 Rise Apr 2002 B1
6397100 Stadler et al. May 2002 B2
6427086 Fischell et al. Jul 2002 B1
6429217 Puskas Aug 2002 B1
6449512 Boveja Sep 2002 B1
6459936 Fischell et al. Oct 2002 B2
6463328 John Oct 2002 B1
6466822 Pless Oct 2002 B1
6473639 Fischell et al. Oct 2002 B1
6473644 Terry, Jr. et al. Oct 2002 B1
6477418 Plicchi et al. Nov 2002 B2
6480743 Kirkpatrick et al. Nov 2002 B1
6484132 Hively et al. Nov 2002 B1
6501983 Natarajan et al. Dec 2002 B1
6505074 Boveja et al. Jan 2003 B2
6532388 Hill et al. Mar 2003 B1
6542774 Hill et al. Apr 2003 B2
6549804 Osorio et al. Apr 2003 B1
6556868 Naritoku et al. Apr 2003 B2
6560486 Osorio et al. May 2003 B1
6564102 Boveja May 2003 B1
6587719 Barrett et al. Jul 2003 B1
6587727 Osorio et al. Jul 2003 B2
6594524 Esteller et al. Jul 2003 B2
6599250 Webb et al. Jul 2003 B2
6609025 Barrett et al. Aug 2003 B2
6610713 Tracey Aug 2003 B2
6611715 Boveja Aug 2003 B1
6615081 Boveja Sep 2003 B1
6615085 Boveja Sep 2003 B1
6622038 Barrett et al. Sep 2003 B2
6622041 Terry, Jr. et al. Sep 2003 B2
6622047 Barrett et al. Sep 2003 B2
6628985 Sweeney et al. Sep 2003 B2
6628987 Hill et al. Sep 2003 B1
6647296 Fischell et al. Nov 2003 B2
6656125 Misczynski et al. Dec 2003 B2
6656960 Puskas Dec 2003 B2
6668191 Boveja Dec 2003 B1
6671555 Gielen et al. Dec 2003 B2
6671556 Osorio et al. Dec 2003 B2
6684105 Cohen et al. Jan 2004 B2
6721603 Zabara et al. Apr 2004 B2
6735474 Loeb et al. May 2004 B1
6738671 Christophersom et al. May 2004 B2
6760626 Boveja Jul 2004 B1
6768969 Nikitin et al. Jul 2004 B1
6788975 Whitehurst et al. Sep 2004 B1
6793670 Osorio et al. Sep 2004 B2
6819953 Yonce et al. Nov 2004 B2
6819956 DiLorenzo Nov 2004 B2
6832114 Whitehurst et al. Dec 2004 B1
6836685 Fitz Dec 2004 B1
6885888 Rezai Apr 2005 B2
6904390 Nikitin et al. Jun 2005 B2
6920357 Osorio et al. Jul 2005 B2
6934580 Osorio et al. Aug 2005 B1
6934585 Schloss Aug 2005 B1
6944501 Pless Sep 2005 B1
6957107 Rogers Oct 2005 B2
6961618 Osorio et al. Nov 2005 B2
6985771 Fischell et al. Jan 2006 B2
6990377 Gliner et al. Jan 2006 B2
7006859 Osorio et al. Feb 2006 B1
7006872 Gielen et al. Feb 2006 B2
7010351 Firlik et al. Mar 2006 B2
7024247 Gliner et al. Apr 2006 B2
7054792 Frei et al. May 2006 B2
7058453 Nelson et al. Jun 2006 B2
7076288 Skinner Jul 2006 B2
7079977 Osorio et al. Jul 2006 B2
7134996 Bardy Nov 2006 B2
7139677 Hively et al. Nov 2006 B2
7146211 Frei et al. Dec 2006 B2
7146217 Firlik et al. Dec 2006 B2
7146218 Esteller et al. Dec 2006 B2
7149572 Frei et al. Dec 2006 B2
7164941 Misczynski et al. Jan 2007 B2
7167750 Knudson et al. Jan 2007 B2
7174206 Frei et al. Feb 2007 B2
7177678 Osorio et al. Feb 2007 B1
7188053 Nikitin et al. Mar 2007 B2
7204833 Osorio et al. Apr 2007 B1
7209786 Brockway Apr 2007 B2
7209787 DiLorenzo Apr 2007 B2
7221981 Gliner May 2007 B2
7228167 Kara Jun 2007 B2
7231254 DiLorenzo Jun 2007 B2
7236830 Gliner Jun 2007 B2
7236831 Firlik et al. Jun 2007 B2
7242983 Frei et al. Jul 2007 B2
7242984 DiLorenzo Jul 2007 B2
7254439 Misczynski et al. Aug 2007 B2
7263467 Sackellares et al. Aug 2007 B2
7277758 DiLorenzo Oct 2007 B2
7280867 Frei et al. Oct 2007 B2
7282030 Frei et al. Oct 2007 B2
7289844 Misczynski et al. Oct 2007 B2
7292890 Whitehurst et al. Nov 2007 B2
7295881 Cohen et al. Nov 2007 B2
7299096 Balzer et al. Nov 2007 B2
7302298 Lowry et al. Nov 2007 B2
7305268 Gliner et al. Dec 2007 B2
7321837 Osorio et al. Jan 2008 B2
7324850 Persen et al. Jan 2008 B2
7324851 DiLorenzo Jan 2008 B1
7346391 Osorio et al. Mar 2008 B1
7353063 Simms, Jr. Apr 2008 B2
7353064 Gliner et al. Apr 2008 B2
7373199 Sackellares et al. May 2008 B2
7389144 Osorio et al. Jun 2008 B1
7401008 Frei et al. Jul 2008 B2
7403820 DiLorenzo Jul 2008 B2
7433732 Carney et al. Oct 2008 B1
7865244 Giftakis et al. Jan 2011 B2
20020072782 Osorio et al. Jun 2002 A1
20020099417 Naritoku et al. Jul 2002 A1
20020116030 Rezai Aug 2002 A1
20020151939 Rezai Oct 2002 A1
20020188214 Misczynski et al. Dec 2002 A1
20030074032 Gliner Apr 2003 A1
20030083716 Nicolelis et al. May 2003 A1
20030083726 Zeijlemaker et al. May 2003 A1
20030125786 Gliner et al. Jul 2003 A1
20030130706 Sheffield et al. Jul 2003 A1
20030144829 Geatz et al. Jul 2003 A1
20030181954 Rezai Sep 2003 A1
20030181958 Dobak Sep 2003 A1
20030208212 Cigaina Nov 2003 A1
20030210147 Humbard Nov 2003 A1
20030212440 Boveja Nov 2003 A1
20030236558 Whitehurst et al. Dec 2003 A1
20040006278 Webb et al. Jan 2004 A1
20040088024 Firlik et al. May 2004 A1
20040122484 Hatlestad et al. Jun 2004 A1
20040122485 Stahmann et al. Jun 2004 A1
20040133119 Osorio et al. Jul 2004 A1
20040138516 Osorio et al. Jul 2004 A1
20040138517 Osorio et al. Jul 2004 A1
20040138647 Osorio et al. Jul 2004 A1
20040138711 Osorio et al. Jul 2004 A1
20040153129 Pless et al. Aug 2004 A1
20040158119 Osorio et al. Aug 2004 A1
20040158165 Yonce et al. Aug 2004 A1
20040172085 Knudson et al. Sep 2004 A1
20040172091 Rezai Sep 2004 A1
20040172094 Cohen et al. Sep 2004 A1
20040176812 Knudson et al. Sep 2004 A1
20040176831 Gliner et al. Sep 2004 A1
20040199212 Fischell et al. Oct 2004 A1
20040249302 Donoghue et al. Dec 2004 A1
20040249416 Yun et al. Dec 2004 A1
20050004621 Boveja et al. Jan 2005 A1
20050020887 Goldberg Jan 2005 A1
20050021092 Yun et al. Jan 2005 A1
20050021103 DiLorenzo Jan 2005 A1
20050021104 DiLorenzo Jan 2005 A1
20050021105 Firlik et al. Jan 2005 A1
20050021106 Firlik et al. Jan 2005 A1
20050021107 Firlik et al. Jan 2005 A1
20050021118 Genau et al. Jan 2005 A1
20050027284 Lozano et al. Feb 2005 A1
20050033378 Sheffield et al. Feb 2005 A1
20050033379 Lozano et al. Feb 2005 A1
20050038484 Knudson et al. Feb 2005 A1
20050049515 Misczynski et al. Mar 2005 A1
20050049655 Boveja et al. Mar 2005 A1
20050065562 Rezai Mar 2005 A1
20050065573 Rezai Mar 2005 A1
20050065574 Rezai Mar 2005 A1
20050065575 Dobak Mar 2005 A1
20050070971 Fowler et al. Mar 2005 A1
20050075701 Shafer Apr 2005 A1
20050075702 Shafer Apr 2005 A1
20050101873 Misczynski et al. May 2005 A1
20050119703 DiLorenzo Jun 2005 A1
20050124901 Misczynski et al. Jun 2005 A1
20050131467 Boveja et al. Jun 2005 A1
20050131485 Knudson et al. Jun 2005 A1
20050131486 Boveja et al. Jun 2005 A1
20050131493 Boveja et al. Jun 2005 A1
20050143786 Boveja et al. Jun 2005 A1
20050148893 Misczynski et al. Jul 2005 A1
20050148894 Misczynski et al. Jul 2005 A1
20050148895 Misczynski et al. Jul 2005 A1
20050153885 Yun et al. Jul 2005 A1
20050154425 Boveja et al. Jul 2005 A1
20050154426 Boveja et al. Jul 2005 A1
20050165458 Boveja et al. Jul 2005 A1
20050187590 Boveja et al. Aug 2005 A1
20050192644 Boveja et al. Sep 2005 A1
20050197590 Osorio et al. Sep 2005 A1
20050245971 Brockway et al. Nov 2005 A1
20050261542 Riehl Nov 2005 A1
20050277998 Tracey et al. Dec 2005 A1
20050283200 Rezai et al. Dec 2005 A1
20050283201 Machado et al. Dec 2005 A1
20050288600 Zhang et al. Dec 2005 A1
20050288760 Machado et al. Dec 2005 A1
20060009815 Boveja Jan 2006 A1
20060074450 Boveja Apr 2006 A1
20060079936 Boveja Apr 2006 A1
20060094971 Drew May 2006 A1
20060095081 Zhou et al. May 2006 A1
20060106430 Fowler et al. May 2006 A1
20060135877 Giftakis et al. Jun 2006 A1
20060135881 Giftakis et al. Jun 2006 A1
20060155495 Osorio et al. Jul 2006 A1
20060167497 Armstrong et al. Jul 2006 A1
20060173493 Armstrong et al. Aug 2006 A1
20060173522 Osorio Aug 2006 A1
20060190056 Fowler et al. Aug 2006 A1
20060195163 KenKnight et al. Aug 2006 A1
20060200206 Firlik et al. Sep 2006 A1
20060212091 Lozano et al. Sep 2006 A1
20060224067 Giftakis et al. Oct 2006 A1
20060224191 DiLorenzo Oct 2006 A1
20060241697 Libbus et al. Oct 2006 A1
20060241725 Libbus et al. Oct 2006 A1
20060293720 DiLorenzo Dec 2006 A1
20070027486 Armstrong et al. Feb 2007 A1
20070027497 Parnis et al. Feb 2007 A1
20070027498 Maschino et al. Feb 2007 A1
20070027500 Maschino et al. Feb 2007 A1
20070032834 Gliner et al. Feb 2007 A1
20070043392 Gliner et al. Feb 2007 A1
20070055320 Weinand et al. Mar 2007 A1
20070073150 Gopalsami et al. Mar 2007 A1
20070073355 DiLorenzo Mar 2007 A1
20070088403 Wyler et al. Apr 2007 A1
20070100278 Frei et al. May 2007 A1
20070100392 Maschino et al. May 2007 A1
20070142862 DiLorenzo Jun 2007 A1
20070142873 Esteller et al. Jun 2007 A1
20070150024 Leyde et al. Jun 2007 A1
20070150025 DiLorenzo et al. Jun 2007 A1
20070161919 DiLorenzo Jul 2007 A1
20070162086 DiLorenzo Jul 2007 A1
20070167991 DiLorenzo Jul 2007 A1
20070173901 Reeve Jul 2007 A1
20070173902 Maschino et al. Jul 2007 A1
20070179534 Firlik et al. Aug 2007 A1
20070179557 Maschino et al. Aug 2007 A1
20070179558 Gliner et al. Aug 2007 A1
20070208212 DiLorenzo Sep 2007 A1
20070213785 Osorio et al. Sep 2007 A1
20070233192 Craig Oct 2007 A1
20070239210 Libbus et al. Oct 2007 A1
20070244407 Osorio Oct 2007 A1
20070249953 Osorio et al. Oct 2007 A1
20070249954 Virag et al. Oct 2007 A1
20070255147 Drew et al. Nov 2007 A1
20070255155 Drew et al. Nov 2007 A1
20070260147 Giftakis et al. Nov 2007 A1
20070260289 Giftakis et al. Nov 2007 A1
20070265536 Giftakis et al. Nov 2007 A1
20070272260 Nikitin et al. Nov 2007 A1
20070282177 Pilz Dec 2007 A1
20080033503 Fowler et al. Feb 2008 A1
20080033508 Frei et al. Feb 2008 A1
20080046035 Fowler et al. Feb 2008 A1
20080064934 Frei et al. Mar 2008 A1
20080071323 Lowry et al. Mar 2008 A1
20080077028 Schaldach et al. Mar 2008 A1
20080103548 Fowler et al. May 2008 A1
20080114417 Leyde May 2008 A1
20080119900 DiLorenzo May 2008 A1
20080125820 Stahmann et al. May 2008 A1
20080139870 Gliner et al. Jun 2008 A1
20080146959 Sheffield et al. Jun 2008 A1
20080161712 Leyde Jul 2008 A1
20080161713 Leyde et al. Jul 2008 A1
20080161879 Firlik et al. Jul 2008 A1
20080161880 Firlik et al. Jul 2008 A1
20080161881 Firlik et al. Jul 2008 A1
20080161882 Firlik et al. Jul 2008 A1
20080183096 Snyder et al. Jul 2008 A1
20080183097 Leyde et al. Jul 2008 A1
Foreign Referenced Citations (18)
Number Date Country
1145736 Oct 2001 EP
1486232 Dec 2004 EP
2026870 Feb 1980 GB
2079610 Jan 1982 GB
0064336 Nov 2000 WO
2004036377 Apr 2004 WO
2005007120 Jan 2005 WO
2005053788 Jun 2005 WO
2005067599 Jul 2005 WO
2006050144 May 2006 WO
2006122148 Nov 2006 WO
2007066343 Jun 2007 WO
2007072425 Jun 2007 WO
2007124126 Nov 2007 WO
2007124190 Nov 2007 WO
2007124192 Nov 2007 WO
2007142523 Dec 2007 WO
2008045597 Apr 2008 WO
Non-Patent Literature Citations (55)
Entry
Bachman, D.,S. et al.; “Effects Of Vagal Volleys And Serotonin On Units Of Cingulate Cortex in Monkeys;” Brain Research , vol. 130 (1977). pp. 253-269.
Baevskii, R.M. “Analysis of Heart Rate Variability in Space Medicine;” Human Physiology, vol. 28, No. 2, (2002); pp. 202-213.
Baevsky, R.M., et al.; “Autonomic Cardiovascular and Respiratory Control During Prolonged Spaceflights Aboard the International Space Station;” J. Applied Physiological, vol. 103, (2007) pp. 156-161.
Boon, P., et al.; “Vagus Nerve Stimulation for Epilepsy, Clinical Efficacy of Programmed and Magnet Stimulation;” (2001); pp. 93-98.
Boon, Paul, et al.; “Programmed and Magnet-Induced Vagus Nerve Stimulation for Refractory Epilepsy;” Journal of Clinical Neurophysiology vol. 18 No. 5; (2001); pp. 402-407.
Borovikova, L.V., et al.; “Vagus Nerve Stimulation Attenuates the Systemic Inflammatory Response to Endotoxin;” Letters to Nature; vol. 405; (May 2000); pp. 458-462.
Brack, Kieran E., et al.; “Interaction Between Direct Sympathetic and Vagus Nerve Stimulation on Heart Rate in the Isolated Rabbit Heart;” Experimental Physiology vol. 89, No. 1; pp. 128-139.
Chakravarthy, N., et al.; “Controlling Synchronization in a Neuron-Level Population Model;” International Journal of Neural Systems, vol. 17, No. 2 (2007) pp. 123-138.
Clark, K.B., et al.; “Posttraining Electrical Stimulation of Vagal Afferents with Concomitant Vagal Efferent Inactivation Enhances Memory Storage Processes in the Rat;” Neurobiology of Learning and Memory, vol. 70, 364-373 (1998) Art. No. NL983863.
Elmpt, W.J.C., et al.; “A Model of Heart Rate Changes to Detect Seizures in Severe Epilepsy” Seizure vol. 15, (2006) pp. 366-375.
Frei, M.G., et al.; “Left Vagus Nerve Stimulation with the Neurocybernetic Prosthesis Has Complex Effects on Heart Rate and on Its Variability in Humans:” Epilepsia, vol. 42, No. 8 (2001); pp. 1007-1016.
George, M.S., et al.; “Vagus Nerve Stimulation: A New Tool for Brain Research and Therapy;” Society of Biological Psychiatry vol. 47 (2000) pp. 287-295.
“Heart Rate Variability—Standards of Measurement, Physiological Interpretation, and Clinical Use” Circulation—Electrophysiology vol. 93, No. 5; http://circ.ahajournals.org/cgi/content-nw/full/93/5/1043/F3.
Henry, Thomas R.; “Therapeutic Mechanisms Of Vague Name Stimulation;”. Neurology, vol. 59 (Supp 4) (Sep. 2002), pp. S3-S14.
Hallowitz et al., “Effects Of Vagal Volleys On Units Of Intralaminar and Juxtalaminar Thalamic Nuclei in Monkeys;” Brain Research, vol. 130 (1977), pp. 271-286.
Iasemidis; L.D., et al.; “Dynamical Resetting of the Human Brain at Epilepctic Seizures: Application of Nonlinear Dynamics and Global Optimization Techniques;” IEEE Transactions on Biomedical Engineering, vol. 51, No. 3 (Mar. 2004); pp. 493-506.
Iasemidis; L.D., et al.; “Spatiotemporal Transition to Epileptic Seizures: A Nonlinear Dynamical Analysis of Scalp and Intracranial EEG Recordings;” Spatiotemporal Models in Biological and Artificial Systems; F.L. Silva et al. (Eds.) IOS Press, 1997; pp. 81-88.
Iasemidis, L.D.; “Epileptic Seizure Prediction and Control” IEEE Transactions on Biomedical Engineering, vol. 50, No. 5 (May 2003); pp. 549-558.
Kautzner, J., et al.; “Utility of Short-Term Heart Rate Variability for Prediction of Sudden Cardiac Death After Acute Myocardial Infarction” Acta Univ. Palacki. Olomuc., Fac. Med., vol. 141 (1998) pp. 69-73.
Koenig, S.A., et al.; “Vagus Nerve Stimulation Improves Severely Impaired Heart Rate Variability in a Patient with Lennox-Gastaut-Syndrome” Seizure (2007) Article in Press—YSEIZ-1305; pp. 1-4.
Koo, B., “EEG Changes With Vagus Nerve Stimulation” Journal of Clinical Neurophysiology, vol. 18 No. 5 (Sep. 2001); pp. 434-441.
Krittayaphong, M.D., et al.; “Heart Rate Variability in Patients with Coronary Artery Disease: Differences in Patients with Higher and Lower Depression Scores” Psychosomatic Medicine vol. 59 (1997) pp. 231-235.
Leutmezer, F., et al.; “Electrocardiographic Changes at the Onset of Epileptic Seizures;” Epilepsia, vol. 44, No. 3; (2003); pp. 348-354.
Lewis, M.E., et al.; “Vagus Nerve Stimulation Decreases Left Ventricular Contractility in Vivo in the Human and Pig Heart” The Journal of Physiology vol. 534, No. 2, (2001) pp. 547-552.
Li, M., et al.; “Vagal Nerve Stimulation Markedly Improves Long-Term Survival After Chronic Heart Failure in Rats;” Circulation (Jan. 2004) pp. 120-124.
Licht, C.M.M.; Association Between Major Depressive Disorder and Heart Rate Variability in the Netherlands Study of Depression and Anxiety (NESDA); Arch. Gen Psychiatry, vol. 65, No. 12 (Dec. 2008); pp. 1358-1367.
Lockard et al., “Feasibility And Safety Of Vagal Stimulation In Monkey Model;” Epilepsia, vol. 31 (Supp. 2) (1990), pp. S20-S26.
McClintock, P., “Can Noise Actually Boost Brain Power” Physics World Jul. 2002; pp. 20-21.
Mori, T., et al.; “Noise-Induced Entrainment and Stochastic Resonance in Human Brain Waves” Physical Review Letters vol. 88, No. 21 (2002); pp. 218101-1-218101-4.
Mormann, F., “Seizure prediction: the long and winding road,” Brain 130 (2007), 314-333.
Nouri, M.D.; “Epilepsy and the Autonomic Nervous System” emedicine (updated May 5, 2006); pp. 1-14; http://www.emedicine.com/neuro/topic658.htm.
O'Regan, M.E., et al.; “Abnormalities in Cardiac and Respiratory Function Observed During Seizures in Childhood” Developmental Medicine & Child Neurlogy, vol. 47 (2005) pp. 4-9.
Pathwardhan, R.V., et al., Control of Refractory status epilepticus precipitated by anticonvulasnt withdrawal using left vagal nerve stimulation: a case report, Surgical Neurology 64 (2005) 170-73.
Poddubnaya, E.P., “Complex Estimation of Adaptation Abilities of the Organism in Children Using the Indices of Responsiveness of the Cardiovascular System and Characteristics of EEG” Neurophysiology vol. 38, No. 1 (2006); pp. 63-74.
Rugg-Gunn, F.J., et al.; “Cardiac Arrhythmias in Focal Epilepsy: a Prospective Long-Term Study” www.thelancet.com vol. 364 (2004) pp. 2212-2219.
Sajadieh, A., et al.; “Increased Heart Rate and Reduced Heart-Rte Variability are Associated with Subclinical Inflammation in Middle-Aged and Elderly Subjects with No Apparent Heart Disease” European Heart Journal vol. 25, (2004); pp. 363-370.
Schernthaner, C., et al.; “Autonomic Epilepsy—The Influence of Epileptic Discharges on Heart Rate and Rhythm” The Middle European Joural of Medicine vol. 111, No. 10 (1999) pp. 392-401.
Terry et al.; “The Implantable Neurocybernetic Prosthesis System”, Pacing and Clinical Electrophysiology, vol. 14, No. 1 (Jan. 1991), pp. 86-93.
Tubbs, R.S., et al.; “Left-Sided Vagus Nerve Stimulation Decreases Intracranial Pressure Without Resultant Bradycardia in the Pig: A Potential Therapeutic Modality for Humans” Child's Nervous System Original Paper; Springer-Verlag 2004.
Umetani, M.D., et al.; “Twenty-Four Hour Time Domain Heart Rate Variability and Heart Rate: Relations to Age and Gender Over Nince Decades” JACC vol. 31, No. 3; (Mar. 1998); pp. 593-601.
Vonck, K., et al. “The Mechanism of Action Of Vagus Nerve Stimulation For Refractory Epilepsy—The Current Status”, Journal of Neurophysiology, vol. 18 No. 5 (2001), pp. 394-401.
Woodbury, et al., “Vagal Stimulation Reduces the Severity Of Maximal Electroshock Seizures in Intact Rats. Use of a Cuff Electrode for Stimulating And Recording”; Pacing and Clinical Electrophysiology, vol. 14 (Jan. 1991), pp. 94-107.
Zabara, J.; “Neuroinhibition of Xylaine Induced Emesis” Pharmacology & Toxicology, vol. 63 (1988) pp. 70-74.
Zabara, J. “Inhibition of Experimental Seizures in Canines by Repetivie Vagal Stimulation” Epilepsia vol. 33, No. 6 (1992); pp. 1005-1012.
Zabara, J., et al.; “Neural Control of Circulation I” The Physiologist, vol. 28 No. 4 (1985); 1 page.
Zabara, J., et al.; “Neuroinhibition in the Regulation of Emesis” Space Life Sciences, vol. 3 (1972) pp. 282-292.
Osorio, Ivan et al., “An Introduction To Contingent (Closed-Loop) Brain Electrical Stimulation For Seizure Blockage, To Ultra-Short-Term Clinical Trials, And To Multidimensional Statistical Analysis Of Therapeutic Efficacy,” Journal Of Clinical Neurophysiology, vol. 18, No. 6, pp. 533-544, 2001.
Osorio, Ivan et al., “Automated Seizure Abaatement In Humans Using Electrical Stimulation,” Annals Of Neurology, vol. 57, No. 2, pp. 258-268, 2005.
Sunderam, Sridhar et al., “Vagal And Sciatic Nerve Stimulation Have Complex, Time-Dependent Effects On Chemically-Induced Seizures: A Controlled Study,” Brain Research, vol. 918, pp. 60-66, 2001.
Weil, Sabine et al, “Heart Rate Increase In Otherwise Sublinical Seizures Is Different In Temporal Versus Extratemporal Seizure Onset: Support For Temporal Lobe Automatic Influence,” Epileptic Disord., vol. 7, No. 3, Sep. 2005, pp. 199-204.
Digenarro, Giancarlo et al., “Ictal Heart Rate Increase Precedes EEG Discharge In Drug-Resistant Mesial Temporal Lobe Seizures,” Clinical Neurophysiology, No. 115, 2004, pp. 1169-1177.
Zijlmans, Maeike et al., “Heart Rate Changes And ECG Abnormalities During Epileptic Seizures: Prevalence And Definition Of An Objective Clinical Sign,” Epilepsia, vol. 43, No. 8, 2002, pp. 847-854.
O'Donovan, Cormac A. et al., “Computerized Seizure Detection Based On Heart Rate Changes,” abstract of AES Proceedings, Epilepsia, vol. 36, Suppl. 4, 1995, p. 7.
Robinson, Stephen E et al., “Heart Rate Variability Changes As Predictor Of Response To Vagal Nerve Stimulation Therapy For Epilepsy,” abstract of AES Proceedings,Epilepsia, vol. 40, Suppl. 7, 1999, p. 147.
Long, Teresa J. et al., “Effectiveness Of Heart Rate Seizure Detection Compared To EEG In An Epilepsy MoitoringUnit (EMU),” abstract of AES Proceedings, Epilepsia, vol. 40, Suppl. 7, 1999, p. 174.
Related Publications (1)
Number Date Country
20130245464 A1 Sep 2013 US
Continuations (1)
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Parent 12258019 Oct 2008 US
Child 13783391 US