Transcutaneous neurostimulator for modulating cardiovascular function

A neurostimulation device includes an external neurostimulator worn by a patient using a bracing element that braces a portion of the patient's body. The external neurostimulator delivers neurostimulation to modulate a cardiovascular function of the patient. In one embodiment, the external stimulator delivers the neurostimulation transcutaneously to a stimulation target in the patient's body using surface stimulation electrodes placed on the body approximately over the stimulation target.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to co-pending, commonly assigned, U.S. patent application Ser. No. 11/548,348, entitled “PERCUTANEOUS NEUROSTIMULATOR FOR MODULATING CARDIOVASCULAR FUNCTION,” filed on even date herewith, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This document relates generally to neurostimulation and particularly to a neurostimulation system for modulating cardiovascular function using an external neurostimulator and surface and/or percutaneous electrodes.

BACKGROUND

Neurostimulation has been applied or proposed to modulate various physiologic functions and treat various diseases. One example is the modulation of cardiovascular functions by stimulating sympathetic and parasympathetic nerves that innervate the heart. Activities in the vagus nerve, including artificially applied electrical stimuli, modulate the heart rate and contractility (strength of the myocardial contractions). Electrical stimulation applied to the vagus nerve is known to decrease the heart rate and the contractility, lengthening the diastolic phase of a cardiac cycle. This ability of the vagal nerve stimulation may be utilized, for example, to control myocardial remodeling. Electrical stimulation applied at acupuncture points is also known to have therapeutic effects in cardiovascular functions.

Neurostimulation is known to provide therapeutic benefit when applied shortly after the occurrence of a cardiac disorder event such as acute MI. For example, after the acute MI, adverse ventricular remodeling starts and the heart is more susceptible to arrhythmias. Neurostimulation may be applied to control the post-MI ventricular remodeling and prevent the arrhythmias from occurring. Thus, there is a need for a neurostimulation system that can be deployed promptly following a cardiac disorder event such as acute MI. Because the post-MI neurostimulation may not be needed on a long-term and/or continuous basis, there is also a need for the neurostimulation system to be suitable for temporary and/or intermittent use.

SUMMARY

A neurostimulation device includes an external neurostimulator worn by a patient using a bracing element that braces a portion of the patient's body. The external neurostimulator delivers neurostimulation to modulate a cardiovascular function of the patient.

In one embodiment, a system for transcutaneous neurostimulation to modulate a cardiovascular function in a body includes a transcutaneous neurostimulation device configured to be worn on the body. The transcutaneous neurostimulation device includes surface stimulation electrodes configured to be placed on surface of the body, an external neurostimulator, and a bracing element. The external neurostimulator delivers neurostimulation transcutaneously to a stimulation target in the body through the surface stimulation electrodes. The bracing element braces a portion of the body to hold the external neurostimulator on a surface location of the body.

In one embodiment, a method is provided for modulating a cardiovascular function in a body by transcutaneous neurostimulation. An external neurostimulator is held on the body using a bracing element configured to brace a portion of the body. Surface stimulation electrodes are placed on the body, with at least one of the surface stimulation electrodes placed approximately over a stimulation target in the body. Neurostimulation is transcutaneously delivered to the stimulation target from the external neurostimulator through the surface stimulation electrodes. The delivery of the neurostimulation is controlled by executing a stimulation algorithm adapted to modulate the cardiovascular function.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. References to “an”, “one”, or “various” embodiments in this disclosure are not necessarily to the same embodiment, and such references contemplate more than one embodiment. The following detailed description provides examples, and the scope of the present invention is defined by the appended claims and their legal equivalents.

This document discusses a neurostimulation system including an external neurostimulator that modulate cardiovascular functions by delivering neurostimulation through transcutaneous and/or percutaneous electrodes. Implantable neurostimulation systems provide post-MI neurostimulation that has anti-remodeling and anti-arrhythmic effects. Recent data suggest maximum benefit to a patient suffering an acute MI is achieved when the neurostimulation is delivered within a week following the acute MI. The implantation of a neurostimulation system may require a substantially invasive operation that can be performed only by specially trained medical personnel. A long-term and/or continuous delivery of the neurostimulation may not be necessary or beneficial. For these and other reasons, a treatment using an implantable neurostimulation system may neither be made available when most needed nor be cost effective. To provide neurostimulation when an implantable neurostimulation system is unavailable, cost ineffective, or otherwise unsuitable, the present neurostimulation system uses an external neurostimulator coupled to transcutaneous and/or percutaneous electrodes. Such a system provides for a potentially fast therapy response to a cardiovascular disorder event such as acute MI and a potentially cost-effective means for delivering neurostimulation on a temporarily and/or intermittent basis.

FIG. 1is an illustration of an embodiment of a neurostimulation system100and portions of an environment in which system100is used. System100includes a neurostimulation device104configured to be worn on a body102of a patient. Neurostimulation device104includes an external neurostimulator110that delivers neurostimulation for modulating the patient's cardiovascular functions, a bracing element112to hold external neurostimulator110onto body102at a specified surface location, and electrodes through which the neurostimulation is delivered from external neurostimulator110to body102. In one embodiment, neurostimulation device104is used as part of an emergency response to a cardiac disorder event occurring in the patient's heart101, such as an acute MI. In another embodiment, neurostimulation device104is used for temporary or intermittent delivery of neurostimulation, such as when the implantation of a neurostimulation system is not justified.

In the illustrated embodiment, neurostimulation device104is donned over the knee area for stimulating the peroneal nerve at an acupuncture point known as GB-34 on the Gall Bladder Meridian of the foot. The acupuncture point GB-34 is also referred to as Yang Ling Quan (Yang Mound Spring) and about one inch below the knee, in the depression on the outer face of the shin, and corresponding to the point where the common peroneal nerve bifurcates into the superficial and deep peroneal nerves. Electrical stimulation at the acupuncture point GB-34 is known to have cardiovascular therapeutic effects such as being anti-remodeling, anti-hypertensive, and anti-arrhythmia. Potential results of electrical stimulation applied to the GB-34 include reduced heart rate, reduced blood pressure, and reduced arrhythmia vulnerability. In various embodiments, neurostimulation device104is used to treat a patient with cardiovascular diseases such as ischemic heart disease, heart failure, and hypertension.

Other acupuncture points known to have cardiovascular effects in response to electrical stimulation include PC-2 to PC-9 (on the Pericardium Meridian, running along the arm from below the armpit fold, along the transverse crease of the wrist, to the tip of the middle finger), HT-7 (on the Heart Meridian, on the transverse crease on the palm side of the wrist), BL-14 (on the Bladder Meridian, about 1.5 inches lateral to the lower border of the spinous process of the fourth thoracic vertebra), BL-16 (on the Bladder Meridian, about 1.5 inches lateral to the lower border of the spinous process of the sixth thoracic vertebra), and GV-11 (on the Governing Vessel Meridian, below the spinous process of the fifth thoracic vertebra).

In one embodiment, the neurostimulation device104is used to stimulate one or more nerves of the autonomic nervous system, such as to module heart rate and blood pressure. Stimulation of the vagus nerve following an acute MI is known to significantly reduce ventricular dilation following coronary artery ligation, manifested as decreased systolic and diastolic volumes.

In various embodiments, bracing element112includes a sleeve, a strap, or a belt configured to brace a portion of body102, such as the knee, wrist, arm, leg, thigh, torso, neck, and head. Brace element112is adjustable in size and/or available in a plurality of sizes to accommodate patients with substantially different sizes.

In one embodiment, neurostimulation device104is a transcutaneous neurostimulation device. External neurostimulator110delivers the neurostimulation to a stimulation target in body102using surface stimulation electrodes placed on stimulation sites on the surface of body102approximately over the stimulation target. In one embodiment, such a transcutaneous neurostimulation device is made for donning by the patient or another person by following simple instructions. Examples of the surface stimulation electrodes used to deliver transcutaneous neurostimulation are discussed below with reference toFIGS. 5-6.

In another embodiment, neurostimulation device104is a percutaneous neurostimulation device. External neurostimulator110delivers the neurostimulation to a stimulation target in body102using at least one percutaneous stimulation electrode that is inserted into body102to lodge on or about a stimulation target in body102. In one embodiment, such a percutaneous neurostimulation device is made available for use by emergency response medical personnel to provide neurostimulation immediately following an acute MI. In another embodiment, the percutaneous neurostimulation device is provided for temporary use while the patient is evaluated or waiting for a more permanent therapy such as an implantable device therapy. In another embodiment, the percutaneous neurostimulation device is used when the stimulation target is difficult to reach by the transcutaneous neurostimulation, thereby expanding the range of potential stimulation targets. Examples of the percutaneous stimulation electrodes used to deliver percutaneous neurostimulation are discussed below with reference toFIGS. 7-11.

FIG. 2is a block diagram illustrating an embodiment of portions of a circuit of system100, including stimulation electrodes214and an external stimulator210. In one embodiment, stimulation electrodes214include surface stimulation electrodes. In another embodiment, stimulation electrodes214include percutaneous stimulation electrodes. In another embodiment, stimulation electrodes214include transcutaneous and percutaneous stimulation electrodes.

External neurostimulator210is a specific embodiment of external neurostimulator110and includes a stimulation output circuit216, a stimulation controller218, and a memory circuit220. Stimulation output circuit216is electrically coupled to stimulation electrodes214and delivers the neurostimulation to a stimulation target in body102through stimulation electrodes214. Stimulation controller218controls the delivery of the neurostimulation by executing a stimulation algorithm for modulating a cardiovascular function. Memory circuit220stores the stimulation algorithm including stimulation parameters.

FIG. 3is a block diagram illustrating another embodiment of portions of the circuit of system100, including stimulation electrodes214, an external neurostimulator310, and an external sensor322. External neurostimulator310is a specific embodiment of external neurostimulator210and includes stimulation output circuit216, a stimulation controller318, a stimulator telemetry circuit324, a battery326, and a user interface328.

Stimulation output circuit216delivers neurostimulation through stimulation electrodes214. In one embodiment, the neurostimulation is in the form of electrical pulses. In other embodiments, the neurostimulation includes any form of energy that is capable of eliciting action potentials in a target nerve, such as magnet field, light, and ultrasound.

Stimulation controller318is a specific embodiment of stimulation controller218and controls the delivery of the neurostimulation by executing a stimulation algorithm for modulating a cardiovascular function. The stimulation algorithm includes stimulation parameters selected to modulate the cardiovascular function. Examples of the stimulation parameters for controlling the delivery of electrical neurostimulation pulses include pulse amplitude, pulse width, stimulation frequency (or inter-pulse interval), periodic dose, and duty cycle. The pulse amplitude and pulse width are selected to ensure that each pulse elicits an action potential in the target nerve. In one embodiment, the stimulation frequency is between approximately 0.1 and 200 Hz, with between approximately 1 and 30 Hz as a specific example for modulating cardiovascular functions. In one embodiment, in which the electrical neurostimulation pulses are delivered transcutaneously using surface electrodes, the stimulation frequency is between approximately 1 and 5 Hz. In one embodiment, in which the electrical neurostimulation pulses are delivered percutaneously using at least one percutaneous electrode, the stimulation frequency is between approximately 1 and 50 Hz. The periodic dose is a time interval during which a patient is treated with neurostimulation for each predetermined period. In one embodiment, the predetermined period is a day, and the periodic dose is a daily dose. The duty cycle is the duty cycle of the neurostimulation during the time interval during of the period dose. For example, if the patient is to receive a neurostimulation therapy for two hours each day, the periodic dose is 2 hours/day (or the daily dose is 2 hours). If the neurostimulation during those two hours is delivered intermittently with alternating on- and off-periods, the duty cycle is the ratio of the on-period to the sum of the on-period and the off-period. In one embodiment, the daily dose is between approximately 0.5 and 24 hours. In one embodiment, the duty cycle is between approximately 10 and 50%. The on-period is between approximately 10 and 120 seconds, and the off-period is between approximately 50 and 120 seconds.

In the illustrated embodiment, stimulation controller318includes a feedback controller330, a command receiver332, a clock334, and an alarm signal generator336. In various embodiments, stimulation controller318includes one or more of feedback controller330, command receiver332, clock334, and alarm signal generator336. Feedback controller330controls the delivery of the neurostimulation using a feedback control signal that indicates a need to start, stop, or adjust the neurostimulation. In one embodiment, the feedback control signal provides for automatic verification of neural response to the neurostimulation. In one embodiment, external sensor322senses the feedback control signal. In a specific embodiment, external sensor332is a sensor included in external neurostimulator310. In another specific embodiment, external sensor332is electrically connected to external neurostimulator310. In another specific embodiment, external sensor332is communicatively coupled to external neurostimulator310via telemetry. Examples of external sensor322include a heart rate sensor to sense a heart rate, a pressure sensor to measure a blood pressure, and a plethysmographic sensor to sense plethysmogram signal. In another embodiment, feedback controller330receives the feedback control signal from stimulator telemetry circuit324. Another device, such as an implantable device in body102or an external device, senses the feedback control signal and telemeters the feedback control signal to external neurostimulator310.

Command receiver332receives a stimulation command for starting, pausing, or stopping the delivery of the neurostimulation. In one embodiment, the stimulation command is received from another device. In another embodiment, the stimulation command is received from user interface328. Clock334keeps track of the time. In one embodiment, clock334times the delivery of a neurostimulation therapy according to a programmed schedule. For example, when the patient is to receive a periodic dose according to the programmed schedule, clock334produces a stimulation command and transmits the stimulation command to command receiver332to starting the delivery of the neurostimulation. Alarm signal generator336generates an alarm signal to remind the patient or another person that the patient is due for receiving the periodic dose of the neurostimulation. In one embodiment, alarm signal generator336generates an alarm signal indicating a problem or potential problem with external neurostimulator310, such as a low battery level. In another embodiment, alarm signal generator336an audio tone as an auditory feedback signal confirming that the neurostimulation delivered from external neurostimulator310is producing desirable result, such as indicated by the feedback control signal.

Memory circuit220stores the stimulation algorithm including the stimulation parameters. In one embodiment, memory circuit220also stores the history of delivery of the neurostimulation. In one example, the patient is given a transcutaneous neurostimulation device and instructed to apply the neurostimulation according to a treatment schedule. If the patient is due to receive the treatment, but the transcutaneous neurostimulation device is not worn or turned on, alarm signal generator336generates an alarm signal as a reminder to the patient.

User interface328includes a presentation device338and a user input device340. Presentation device338includes a display342and an audio tone generator344. In one embodiment, display342a liquid crystal display (LCD) screen. Display342displays information including, but not limited to, power on/off status of the external neurostimulator, parameters produced using signal sensed by external sensor322(such as the heart rate and the blood pressure), the time, and the battery status. User input device340includes a power switch346and a stimulation intensity adjuster348. Power switch328allows the patient or another person to turn external neurostimulator310on and off. Stimulation intensity adjuster348allows the patient or another person to adjust the stimulation parameters to change the intensity of the neurostimulation. In one embodiment, display342indicates whether the neurostimulation elicits an expected response, and the patient can use stimulation intensity adjuster348to change the intensity of the neurostimulation if the current intensity causes discomfort. In another embodiment, feedback controller330adjusts the intensity of the neurostimulation automatically using the feedback control signal such that stimulation intensity adjuster348is unnecessary.

Battery326supplies the power for the operation of the circuit of external neurostimulator310. In one embodiment, battery326is a rechargeable battery. In one embodiment, the patient using system100is provided with a battery charger that uses standard AC power. When needed, the battery charger is equipped with one or more adaptors for use in different countries.

FIG. 4is an illustration of an embodiment of an external neurostimulator410, which is a specific embodiment of external neurostimulator110.FIG. 4shows a front view of external neurostimulator410, which includes a chassis454to house a circuit such as the circuit of external neurostimulator210or310. A user interface including a display442and user input device440are incorporated onto chassis454. Display442represents an embodiment of display342. User input device440represents an embodiment of user input device340and includes buttons, knobs, and/or other switches that are operated by the patient or another person.

FIG. 5is an illustration of an embodiment of surface stimulation electrodes coupled to external neurostimulator410.FIG. 5shows a rear view of external neurostimulator410. Surface stimulation electrodes556A-B are incorporated onto the side of chassis454that is in contact of the surface of body102when being used. External neurostimulator410is placed on a surface location of body102such that surface stimulation electrodes556A-B are positioned approximately over a stimulation target in body102. In one embodiment, surface stimulation electrodes556A-B each have a surface area between approximately 5 and 100 mm2.

In the illustrated embodiment, surface stimulation electrodes556A-B are shown as disc electrodes for illustrate purposes only. Other examples of the configuration of surface stimulation electrodes556A-B include strip electrodes, ring electrodes, and concentric electrodes.

FIG. 6is an illustration of another embodiment of surface stimulation electrodes coupled to external neurostimulator410. Surface stimulation electrodes656A-B are each connected to external neurostimulator410using a lead. In the illustrated embodiment, surface stimulation electrodes656A is connected to external neurostimulator410using a lead658A, and is incorporated onto a skin patch659A. Surface stimulation electrodes656B is connected to external neurostimulator410using a lead658B, and is incorporated onto a skin patch659B. Skin patches659A-B are attached to the surface of body102using adhesive. In another embodiment, surface stimulation electrodes656A-B are incorporated onto a single skin patch and connected to external neurostimulator410using a multi-conductor lead.

FIG. 7is an illustration of an embodiment of percutaneous stimulation electrodes coupled to external neurostimulator410. Percutaneous stimulation electrodes756A-B are each configured to pierce the skin of body102and lodge in a specified stimulation site in body102. The specific stimulation site is on or about a target nerve.

Percutaneous stimulation electrodes756A-B are each a wire electrode including a wire having a proximal end coupled to external neurostimulator410and a distal end configured to lodge in the specified stimulation site in body102. In one embodiment, the wire includes a coiled portion such that when each of electrodes756A-B exits body102, the wire is coiled as it exits the skin. The coiled portion is employed to reduce the likelihood of infection with percutaneous wires because greater mechanical stability and encapsulation are achieved with the coiled wire. In the illustrated embodiment, the wire electrode is a needle electrode, where the wire is substantially rigid. The distal end is a sharp tip suitable for penetrating tissue and includes barbs (760A or760B) to provide a stable electrode placement. In the illustrated embodiment, percutaneous stimulation electrodes756A-B are mounted on and projecting from external neurostimulator410. In another embodiment, percutaneous stimulation electrodes756A-B are each connected to external neurostimulator410using a lead.

FIG. 8is an illustration of an embodiment of percutaneous stimulation electrodes coupled to external neurostimulator410. Percutaneous stimulation electrodes856A-B are each a wire electrode including a wire having a proximal end coupled to external neurostimulator410and a distal end configured to lodge in the specified stimulation site in body102. In one embodiment, the wire includes a coiled portion such that when each of electrodes856A-B exits body102, the wire is coiled as it exits the skin. In the illustrated embodiment, the wire electrode is a flexible electrode, where the wire is substantially flexible. Percutaneous stimulation electrodes856A-B each includes a distal end that is a J-shaped hook (860A or860B). In one embodiment, percutaneous stimulation electrodes856A-B are each introduced into tissue with a hollow needle.

FIG. 9is an illustration of an embodiment of percutaneous stimulation electrodes coupled to external neurostimulator410. An implantable capsule962includes percutaneous stimulation electrodes956A-B each on one of its opposite ends. To deliver the neurostimulation, capsule962is subcutaneously implanted, and a multi-conductor lead958provides percutaneous connections between each of percutaneous stimulation electrodes956A-B and external neurostimulator410. In one embodiment, capsule962has a cylindrical elongate body coupled between opposite ends. The length of capsule between the opposite ends is between approximately 5 mm and 25 mm. The cylindrical elongate body has a diameter between approximately 1 mm and 10 mm. In one embodiment, capsule962is implanted by injection through a hollow injection device having an end configured to reach the stimulation target in body102. Examples of the hollow injection device include a hollow needle and hollow catheter.

FIG. 10is an illustration of an embodiment of a percutaneous stimulation electrode1056coupled to external neurostimulator410through a skin-mounted connector1064. Connector1064includes a button mounted on a surface location of body102and is electrically connected to percutaneous stimulation electrode1056. Connector1066is to be connected to connector1064and to external neurostimulator410through a lead1058. In one embodiment, connectors1064and1066are button-connectors allowing for a snap-on connection. In another embodiment, connectors1064and1066are flat discs including magnets to hold to each other magnetically. In another embodiment, connectors1064and1066are a pair of slot and groove slide-in connectors with latch and push-button release. The use of connectors1064and1066allows external neurostimulator410to be disconnected from percutaneous stimulation electrode1056, for example, when the patient is not treated with the neurostimulation. The use of these connectors also provide mechanical strain relief. In various embodiments, percutaneous stimulation electrode1056includes any electrode suitable for implantation in body102to deliver the neurostimulation, with electrode756A/B being a specific example.

FIG. 11is an illustration of an embodiment of a percutaneous stimulation electrode coupled to external neurostimulator410through a lead1158with a magnet1168. Capsule962, which includes percutaneous stimulation electrodes956A-B, is to be electrically connected to external neurostimulator410through lead1158. Magnet1168is coupled to lead1158and is to be placed onto a surface location of body102over implanted capsule962to prevent capsule962from drifting in the tissue.

FIGS. 5-11illustrate various stimulation electrode configurations as specific examples of surface and percutaneous stimulation electrodes. A transcutaneous neurostimulation device includes at least a pair of surface stimulation electrode. A percutaneous neurostimulation device includes at least one percutaneous stimulation electrode. In one embodiment, the neurostimulation is delivered using a pair of percutaneous stimulation electrodes. In another embodiment, the neurostimulation is delivered using a percutaneous stimulation electrode placed on or about the stimulation target and a surface stimulation electrode serving as a return electrode. Some additional examples of electrode configurations are discussed below with reference toFIGS. 18-21. In various embodiments, neurostimulation is delivered transcutaneously or percutaneously using a pair of stimulation electrodes selected from any of those illustrated inFIGS. 5-11as well as any other suitable surface and percutaneous electrodes.

FIG. 12is an illustration of an embodiment of external neurostimulator410coupled to a bracing element. A neurostimulation device1214includes external neurostimulator410affixed to a bracing element1212. Bracing element1212is configured to brace a portion of body102to hold external neurostimulator410onto the surface of body102. In one embodiment, in which neurostimulation device1214is a transcutaneous neurostimulation device, bracing element1212allows surface stimulation electrodes on external neurostimulator410(such as electrodes556A-B) to be placed securely on a surface location of body102approximately over a stimulation target in body102. In another embodiment, in which neurostimulation device1214is a percutaneous neurostimulation device, bracing element1212allows external neurostimulator410to be worn on a surface location of body102over or near a stimulation target in body102on or about which at least one percutaneous stimulation electrode is lodged. In the illustrated embodiment, bracing element1212includes a belt. In one embodiment, belt1212is detachably coupled to external neurostimulator410. In one embodiment, belt1212has an adjustable length. In one embodiment, belt1212includes a wrist band, and neurostimulation device1214has a configuration similar to a wrist watch. In other embodiments, belt1212has a length suitable for bracing another portion of body102, such as the knee, arm, leg, thigh, torso, neck, or head.

FIG. 13is an illustration of another embodiment of external neurostimulator410coupled to a bracing element. An neurostimulation device1314includes external neurostimulator410affixed to a bracing element1312, which has substantially same functions as bracing element1212except for being a sleeve. The choice between using belt1212and sleeve1312may depend on factors such as location on body102and patient preference. In one embodiment, sleeve1312is detachably coupled to external neurostimulator410. In one embodiment, sleeve1312is made of an elastic material to provide an adjustable length. In one embodiment, sleeve1312includes a knee sleeve, and neurostimulation device1314is worn as a knee guard. In other embodiments, sleeve1312has a length suitable for bracing another portion of body102, such as the wrist, arm, leg, thigh, torso, neck, or head.

External neurostimulator410is illustrated inFIGS. 4-9,12, and13as a specific example and not as a restriction. In various embodiments, the external neurostimulator of the present neurostimulation system may have any configuration suitable for being incorporated into a neurostimulation device worn by the patient, such as neurostimulation device104, to deliver transcutaneous and/or percutaneous neurostimulation as discussed in this document.

FIG. 14is an illustration of an embodiment of a neurostimulation system1400. System1400includes a neurostimulation device1404, an implantable medical device1470, and an external system1474. Neurostimulation device1404is a specific embodiment of neurostimulation device104and includes an external neurostimulator1410coupled to bracing element112. In one embodiment, external neurostimulator1410includes the circuit of external neurostimulator310as discussed above. A telemetry link1411provides for communication between external neurostimulator1410and implantable medical device1470. A telemetry link1413provides for communication between implantable medical device1470and external system1474. A telemetry link1475provides for communication between external neurostimulator1410and external system1474.

In one embodiment, implantable medical device1470includes an implantable cardiac rhythm management (CRM) device. Implantable medical device1470includes, but is not limited to, one or more of a pacemaker, a cardioverter/defibrillator, a cardiac resynchronization therapy device, a cardiac remodeling control therapy device, a neurostimulation device, a drug delivery device, a biologic therapy device, and a patient monitoring device. A lead system1472includes one or more leads providing for electrical and/or other connections between heart101and implantable medical device110.

External system1474allows for programming of implantable medical device1470and/or external neurostimulator1410and receives signals acquired by implantable medical device1470and/or external neurostimulator1410. In one embodiment, external system1474includes a programmer. In another embodiment, external system1474is a patient management system including an external device in proximity of body102(in which implantable medical device1470is implanted and on which neurostimulation device1404is worn), a remote device in a relatively distant location, and a telecommunication network linking the external device and the remote device. The patient management system allows for access to implantable medical device1470and/or external neurostimulator1410from a remote location, such as for monitoring patient status, adjusting therapies, and obtaining patient's medical records stored in a remote location.

Telemetry link1413is a wireless communication link providing for data transmission between implantable medical device1470and external system1474. Telemetry link1413provides for data transmission from implantable medical device1470to external system1474. This may include, for example, transmitting real-time physiological data acquired by implantable medical device1470, extracting physiological data acquired by and stored in implantable medical device1470, extracting therapy history data stored in implantable medical device1470, and extracting data indicating an operational status of implantable medical device1470(e.g., battery status and lead impedance). Telemetry link1413also provides for data transmission from external system1474to implantable medical device1470. This may include, for example, programming implantable medical device1470to acquire physiological data, programming implantable medical device1470to perform at least one self-diagnostic test (such as for a device operational status), programming implantable medical device1470to enable an available monitoring or therapeutic function, and programming implantable medical device1470to adjust therapeutic parameters such as pacing and/or cardioversion/defibrillation parameters.

Telemetry link1475is a wireless communication link providing for data transmission between external neurostimulator1410and external system1474. Telemetry link1475provides for data transmission from external neurostimulator1410to external system1474. This may include, for example, transmitting real-time physiological data acquired by external neurostimulator1410, extracting physiological data acquired by and stored in external neurostimulator1410, extracting therapy history data stored in external neurostimulator1410, and extracting data indicating an operational status of external neurostimulator1410(e.g., battery status). Telemetry link1475also provides for data transmission from external system1474to external neurostimulator1410. This may include, for example, programming external neurostimulator1410to adjust the stimulation parameters, and transmitting a user command to external neurostimulator1410to initiate a delivery of the neurostimulation.

Telemetry link1411is a wireless communication link providing for data transmission between external neurostimulator1410and implantable medical device1470. Telemetry link1475provides for data transmission from implantable medical device1470to external neurostimulator1410. This may include, for example, transmitting a signal sensed by implantable medical device1470to external neurostimulator1410for use as the feedback control signal controlling the neurostimulation, and transmitting a neurostimulation command to external neurostimulator1410to initiate a delivery of the neurostimulation, such as when a predetermined-type cardiac event is detected by implantable medical device1470. In one embodiment, telemetry link1475also provides for data transmission from external neurostimulator1410to implantable medical device1470.

System1400allows the neurostimulation to be initiated by any one of external neurostimulator1410, implantable medical device1470, and external system1474. In one embodiment, external neurostimulator1410and/or implantable medical device1470initiate a neurostimulation therapy upon detecting a predetermined signal or condition. External system1474initiates a neurostimulation therapy upon receiving a user command.

FIG. 15is a block diagram illustrating an embodiment of portions of a circuit of system1400. The circuit includes an implantable medical device1570coupled to lead system1472, an external system1574, and external neurostimulator310coupled to stimulation electrodes214.

Implantable medical device1570is a specific embodiment of implantable medical device1470and includes a CRM circuit1580, a sensor1576, a sensor processing circuit1578, a command generator1582, and an implant telemetry circuit1584. CRM circuit1580delivers one or more CRM therapies. In one embodiment, CRM circuit1580includes one or more of a pacemaker and a cardioverter/defibrillator to delivery cardiac electrical stimulation to heart101through lead system1472. Sensor1576senses a physiologic signal. Sensor processing circuit1578produces the feedback control signal used by feedback controller330of external neurostimulator310using the sensed physiologic signal. In one embodiment, the physiological signal is a cardiac signal, and the feedback control signal is indicative of a cardiac condition to be modulated by the neurostimulation. Command generator1582produces the neurostimulation command that initiates a neurostimulation therapy, such as upon detecting a specified-type cardiac event (such as ischemia or MI) from the cardiac signal. Implant telemetry circuit1584transmits the feedback control signal and/or the neurostimulation command to the external neurostimulator310.

External system1574includes a user interface1586, a programming module1588, and an external telemetry circuit1590. User interface1586allows a user such as a physician or other caregiver to program implantable medical device1570and/or external neurostimulator310and observe signals acquired by implantable medical device1470and/or external neurostimulator310. Programming module1588converts user input received by user interface1586to programming codes to be transmitted to implantable medical device1470and/or external neurostimulator310by external telemetry circuit1590. In the illustrated embodiment, user interface1586allows the user to enter the user command for initiating a neurostimulation therapy, and programming module1588includes a command generator1592to produce the neurostimulation command upon receiving the user command for initiating the neurostimulation therapy. External telemetry circuit1590transmits the neurostimulation command to external neurostimulator310.

FIG. 16is an illustration of an embodiment of a neurostimulation system1600. System1600includes a neurostimulation device1604and a user communication device1605. Neurostimulation device1604is a specific embodiment of neurostimulation device104and includes an external neurostimulator1610coupled to bracing element112. User communication device1605includes a communicator1611and a bracing element1613. In one embodiment, external neurostimulator1610includes substantially the circuit of external neurostimulator310except user interface328, which is included in communicator1611. A telemetry link1615provides for communication between external neurostimulator1610and communicator1611. System1600provides for easy access to and observation of a user interface when the external stimulator is held onto a bodily location that is not convenient to reach and see by at least the patient wearing the external stimulator, such as the knee or the neck. User communication device1605is a portable device that is carried or worn by the patient in a way allowing for convenient access by the patent. When user communication device1605is worn by the patient, bracing element1613holds communicator1611on body102by bracing a portion of body102, such as the lower arm or wrist. In the illustrated embodiment, neurostimulation device1604is configured to be worn on the knee area, such as for stimulating the peroneal nerve at the acupuncture point GB-34, and user communication device1605is configured to be worn on a wrist, in the form of a wrist watch. In a specific embodiment, user communication device1605has the appearance of the neurostimulation device1214as illustrated inFIG. 12.

FIG. 17is a block diagram illustrating an embodiment of portions of a circuit of system1600. The circuit includes a communicator1711and external neurostimulator1710coupled to stimulation electrodes214and sensor322. Communicator1711includes user interface328and a communicator telemetry circuit1794. External neurostimulator1710includes stimulation output circuit216, stimulation controller318, memory circuit220, stimulator telemetry circuit324, and battery326. Communicator telemetry circuit1794and stimulator telemetry circuit324perform bi-directional communication between user interface328and stimulation controller318via telemetry link1615. The circuit is substantially similar to the circuit inFIG. 3except that user interface328is communicatively coupled to stimulation controller318via telemetry link1615.

FIGS. 18-21illustrate additional examples of stimulation electrodes coupled to external neurostimulator410, including its various embodiments discussed in this document. In various embodiments, neurostimulation is delivered transcutaneously and/or percutaneously using one or more pairs of stimulation electrodes such as those illustrated inFIGS. 5-11and18-21, as well as any other suitable pairs of surface and/or percutaneous electrodes.

FIG. 18is an illustration of another embodiment of surface stimulation electrodes coupled to external neurostimulator410. Surface stimulation electrode656A is connected to external neurostimulator410using lead658A and is incorporated onto skin patch659A, as discussed above with reference toFIG. 6. A surface stimulation electrode1856B is incorporated onto the side of the chassis of external neurostimulator410that is in contact of the surface of body102when being used. One example of surface stimulation electrodes1856B is surface stimulation electrode556A/B as discussed above. The electrode configuration illustrated inFIG. 18differs from the electrode configuration illustrated inFIG. 6in that one of the surface electrodes is connected to external neurostimulator410using a lead, extending the range of stimulation targets with external neurostimulator410placed on a surface location of body102. This provides for transcutaneous neurostimulation when, for example, it is difficult to place external neurostimulator410approximately over the stimulation target in body102.

FIG. 19is an illustration of an embodiment of surface and percutaneous stimulation electrodes coupled to external neurostimulator410. Percutaneous stimulation electrode756A is a wire electrode including a wire having a proximal end coupled to external neurostimulator410and a distal end configured to lodge in the specified stimulation site in body102, as discussed above with reference toFIG. 7. A surface stimulation electrode1956B is incorporated onto the side of the chassis of external neurostimulator410that is in contact of the surface of body102when being used. One example of surface stimulation electrodes1956B is surface stimulation electrode556A/B as discussed above. The electrode configuration illustrated inFIG. 19differs from the electrode configuration illustrated inFIG. 7in that one of the percutaneous electrodes is replaced by a surface electrode. This reduces the degree the invasiveness of the neurostimulation therapy.

FIG. 20is an illustration of another embodiment of surface and percutaneous stimulation electrodes coupled to external neurostimulator410. Percutaneous stimulation electrodes856A is a wire electrode including a wire having a proximal end coupled to external neurostimulator410and a distal end configured to lodge in the specified stimulation site in body102, as discussed above with reference toFIG. 8. A surface stimulation electrode2056B is incorporated onto the side of the chassis of external neurostimulator410that is in contact of the surface of body102when being used. One example of surface stimulation electrodes2056B is surface stimulation electrode556A/B as discussed above. The electrode configuration illustrated inFIG. 20differs from the electrode configuration illustrated inFIG. 8in that one of the percutaneous electrodes is replaced by a surface electrode. This reduces the degree the invasiveness of the neurostimulation therapy.

FIG. 21is an illustration of another embodiment of surface and percutaneous stimulation electrodes coupled to external neurostimulator410. An implantable capsule2162includes a percutaneous stimulation electrodes2156A on one of its opposite ends. To deliver the neurostimulation, capsule2162is subcutaneously implanted, and a lead2158provides a percutaneous connection between percutaneous stimulation electrode2156A and external neurostimulator410. Implantable capsule2162is substantially similar to implantable capsule962except that only one stimulation electrode is required to be incorporated onto the capsule. A surface stimulation electrode2156B is incorporated onto the side of the chassis of external neurostimulator410that is in contact of the surface of body102when being used. One example of surface stimulation electrodes2156B is surface stimulation electrode556A/B as discussed above. The electrode configuration illustrated inFIG. 21differs from the electrode configuration illustrated inFIG. 9in that one of the stimulation electrodes is replaced by a surface electrode. This increases the distance between the pair of stimulation electrodes when needed.

FIG. 22is a flow chart illustrating a method2200for modulating a cardiovascular function using transcutaneous or percutaneous neurostimulation. In one embodiment, the method is performed by system100,1400, or1600.

An external neurostimulator is donned onto a patient at2210, upon determination that the patient is likely to benefit from a transcutaneous or percutaneous neurostimulation therapy. In one embodiment, the patient has suffered an acute MI. The external neurostimulator is held to a surface location of the patient's body using a bracing element such as a belt, a strap, or a sleeve that braces a portion of the body. In one embodiment, the transcutaneous or percutaneous neurostimulation therapy is applied when the patient is waiting to receive an implantable neurostimulator, when the use of an implantable neurostimulator is not justified, or when the use of an external neurostimulator is more beneficial to the patient when compared to the use of an implantable neurostimulator for medical, administrative, and/or economical reasons.

Surface and/or percutaneous electrodes are placed at2212. Surface electrodes are used to deliver the transcutaneous neurostimulation therapy. Percutaneous and/or surface electrodes are used to deliver the percutaneous neurostimulation therapy. Examples of the surface and/or percutaneous electrodes include those illustrated inFIGS. 5-11and18-21, while all electrodes suitable for delivering transcutaneous or percutaneous neurostimulation therapy may be used. Factors determining the choice between the transcutaneous neurostimulation therapy and the percutaneous neurostimulation therapy include, for example, whether the patient or a trained medical personnel administers the therapy delivery, location of the intended stimulation target, device availability, and duration and/or frequency of the use of the neurostimulation device.

The delivery of the neurostimulation is controlled by executing a stimulation algorithm for modulating a cardiovascular function at2214. In one embodiment, the execution of the stimulation algorithm is initiated by a neurostimulation command received from a user or another device. In one embodiment, the stimulation algorithm provides for an open-loop neurostimulation using predetermined stimulation parameters. In another embodiment, the stimulation algorithm provides for a closed-loop neurostimulation using a feedback control signal to adjust the stimulation parameters, including the starting and stopping of the delivery of the neurostimulation. In one embodiment, the feedback control signal is indicative of whether the neurostimulation elicits the intended response from the target nerve. Examples of the feedback control signal include a cardiac signal, a blood pressure signal, a plethysmographic signal, and any other signal indicative of cardiac functions and/or hemodynamic performance of the patient.

The neurostimulation is delivered through the surface and/or percutaneous electrodes at2216. In one embodiment, the neurostimulation is a stand-alone therapy. In another embodiment, the neurostimulation is supplemental to a cardiac stimulation therapy such as a cardiac remodeling control therapy and/or other therapies such as drug and biologic therapies.