Abstract: A method is presented for evaluating whether an episode of sleep apnea is occurring in a patient suffering from chronic sleep apnea disorder, for delivery of appropriate therapy. The method, performed by an implantable device, includes sensing the patient's EKG signal and using electrical energy generated by the heart to power subsequent signal processing. This signal is applied as the sole input to a differential signal processing circuit for passage through both a high impedance path and a substantially lower impedance path and amplification of the difference in magnitude between the resulting two signals, to determine changes in the patient's thoracic impedance. Based on such changes, the presence or absence of patient ventilation is detected, to enable an assessment of whether an episode of sleep apnea is occurring. An actual episode of sleep apnea is deemed to have occurred if lack of ventilation exceeds a predetermined interval of time between otherwise regular respiratory cycles.

Abstract: An embodiment relates to a method for delivering a vagal stimulation therapy to a vagus nerve, including delivering a neural stimulation signal to non-selectively stimulate both afferent axons and efferent axons in the vagus nerve according to a predetermined schedule for the vagal stimulation therapy, and selecting a value for at least one parameter for the predetermined schedule for the vagal stimulation therapy to control the neural stimulation therapy to avoid physiological habituation to the vagal stimulation therapy. The parameter(s) include at least one parameter selected from the group of parameters consisting of a predetermined therapy duration parameter for a predetermined therapy period, and a predetermined intermittent neural stimulation parameter associated with on/off timing for the intermittent neural stimulation parameter.

Abstract: A method of identifying a potential cause of pulmonary edema is provided. The method includes obtaining one or more impedance vectors between predetermined combinations of the electrodes positioned proximate the heart. At least one of the impedance vectors is representative of a thoracic fluid level. The method also includes applying a stimulation pulse to the heart and sensing cardiac signals of the heart that are representative of an electrophysiological response to the stimulation pulse. The method further includes monitoring the cardiac signals and at least one of the impedance vectors with respect to time to identify the potential cause of pulmonary edema.

Abstract: A method includes controlling a cardiac pacing rate of an implantable medical device to control a heart rate of a patient and detecting inhalation and exhalation of the patient. The method further includes determining that the patient is in a resting state, and, in response to determining that the patient is in the resting state, incrementally increasing the pacing rate while exhalation of the patient is detected and incrementally decreasing the pacing rate while inhalation of the patient is detected.

Abstract: A method includes controlling a cardiac pacing rate of an implantable medical device (IMD) to control a heart rate of a patient and determining that the patient is in a resting state. The method further includes modifying the pacing rate of the IMD for N cardiac cycles in response to determining that the patient is in the resting state. N is an integer greater than 1. Modifying the pacing rate includes incrementally increasing the pacing rate for a first portion of the N cardiac cycles, and incrementally decreasing the pacing rate for a second portion of the N cardiac cycles.

Abstract: Adaptive rate pacing for improving heart rate kinetics in heart failure patients involves determining onset and sustaining of patient activity. The patient's heart rate response to the sustained activity is evaluated during a time window defined between onset of the activity and a steady-state exercise level. If the patient's heart rate response to the sustained activity is determined to be slow, a pacing therapy is delivered at a rate greater than the patient's intrinsic heart rate based on a profile of the patient's heart rate response to varying workloads. If determined not to be slow, the pacing therapy is withheld. Monitoring-only configurations provide for acquisition and organization of physiological data for heart failure patients. These data can be acquired on a per-patient basis and used to assess the HF status of the patient.

Abstract: A cardiac rhythm management device for obtaining transthoracic impedance. The device comprises a sensor for obtaining a signal indicative of an action of a heart, an impedance measurement circuit adapted to measure transthoracic impedance and a processor for utilizing the signal indicative of the action of the heart to sample the transthoracic impedance at sampling intervals commenced by fiducial markers in the signal indicative of the action of the heart, where the sampling of the impedance signal removes the component of a stroke volume of the heart from the signal and thereby provides lung ventilation information.

Abstract: Systems, devices and methods for defining, identifying and utilizing composite parameter indices from health-related parameters are disclosed. One aspect is a programmable device having machine executable instructions for performing a method to assist with managing a patient's health. In various embodiments, a first set of at least two health-related parameters is acquired. A first composite parameter is generated using the first set of at least two health-related parameters. Other aspects and embodiments are provided herein.

Abstract: A device and method for detecting and treating airflow limitations in a subject is provided. Levels of flow limited breathing may be differentiated. Obstruction versus flow limited breathing may be differentiated as well. The EMG complex characteristics may be used to detect obstruction or flow limited breathing. The power spectral density plot of the EMG may be used to detect obstruction or flow limited breathing.

Abstract: Various aspects of the present subject matter provide an implantable medical device. In various embodiments, the device comprises a pulse generator, a lead, a sensor, and a controller. The pulse generator generates a baroreflex stimulation signal as part of a baroreflex therapy. The lead is adapted to be electrically connected to the pulse generator and to be intravascularly fed into a heart. The lead includes an electrode to be positioned in or proximate to the heart to deliver the baroreflex signal to a baroreceptor region in or proximate to the heart. The sensor senses a physiological parameter regarding an efficacy of the baroreflex therapy and provides a signal indicative of the efficacy. The controller is connected to the pulse generator to control the baroreflex stimulation signal and to the sensor to receive the signal indicative of the efficacy of the baroreflex therapy. Other aspects are provided herein.

Abstract: A method is provided for trending heart failure based on heart contractility information comprises measuring cardiogenic impedance (CI) measurements along at least a first vector through a heart over a period of time. The method determines contractility estimates from the CI measurements, the contractility estimates relating to contractility of the heart. The method further obtains physiologic and/or surrogate signals representing estimates for or direct measurements of at least one of cardiac volume and pressure of the heart when the CI measurements were obtained. The method identifies correction factors based on the physiologic and/or surrogate signals and applies the correction factors to the contractility estimates to produce contractility trend values over the period of time.

Abstract: A device and method are provided to treat heart failure by stimulating to cause diaphragm contraction.

Abstract: Methods and systems to modulate timing intervals for pacing therapy are described. For each cardiac cycle, one or both of an atrioventricular (A-V) timing interval and an atrial (A-A) timing interval are modulated to oppose beat-to-beat ventricular (V-V) timing variability. Pacing therapy is delivered using the modulated timing intervals.

Abstract: The invention relates to methods and systems for determining phase-specific parameters of a physiological variable, and a related computer program and a related machine-readable storage medium, which are usable in particular to determine parameters of physiological variables that are subject to circadian variation. To this end, phase-specific parameters of a physiological variable X(t) are determined by calculating, at least for a portion of values x lying in a specifiable time period, a mean g(x|?) in each case of values X(t+?) for which X(t)=x applies for their predecessors, ? describing a time interval, and determining the phase-specific parameters by evaluating the mean g(x|?).

Abstract: A method for detecting a condition of a heart of a patient using an implantable medical device, including the steps of sensing acoustic signals indicative of heart sounds of the heart of the patient; extracting signals corresponding to a first heart sound (S1) and a second heart sound (S2) from sensed signals; calculating an energy value corresponding to a signal corresponding to the first heart sound (S1) and an energy value corresponding to the second heart sound (S2); calculating a relation between the energy value corresponding to the first heart sound and the energy value corresponding to the second heart sound for successive cardiac cycles; and using at least one relation to detect the condition or a change of the condition. A medical device for determining the posture of a patient and a computer readable medium encoded with instructions are used to perform the inventive method.

Abstract: A neural stimulation system controls the delivery of neural stimulation using a respiratory signal as a therapy feedback input. The respiratory signal is used to increase the effectiveness of the neural stimulation, such as vagal nerve stimulation, while decreasing potentially adverse side effects in respiratory functions. In one embodiment, the neural stimulation system detects apnea and, in response, adjusts the delivery of the neural stimulation pulses and/or delivers a respiratory therapy treating the detected apnea.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a plurality of sensors sensing cardiac signals, and a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals. A microprocessor detects a cardiac event in response to the sensed cardiac signals, computes a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determines whether the sensed cardiac signals are associated with noise in response to the computed variation index, and confirms the determined cardiac event in response to the sensed cardiac signals not being associated with noise.

Abstract: A system and method for automatically adjusting the operating parameters of a rate-adaptive cardiac pacemaker. In accordance with the method, maximum exertion levels attained by the patient are measured at periodic intervals and stored. The stored maximum exertion levels may then be used to update a long-term maximal exertion level, and the slope of the rate-response curve is adjusted to map the updated long-term maximal exertion level to a maximum allowable pacing rate. The stored maximum exertion levels may also be used to update a sensor target rate which is used to adjust the slope of the rate response curve.

Abstract: A method of providing cardiac stimulation therapy and a device for providing the therapy. A patient's cardiac activity as well as cyclical respiration is monitored. Cardiac stimulation is provided as indicated as therapeutic intervention for a variety of cardiac arrhythmias according to variable timing parameters. One or more of the timing parameters under which cardiac pacing stimulations are provided is varied or modulated with the cyclical variations in respiration. The one or more timing parameters are generally shortened or elongated in concert with the alternating inspiration/exhalation phases of respiration. In certain implementations, the patient's respiration is inferred from cardiac based physiologic signals. The methods and devices for providing cardiac stimulation therapy more accurately emulate natural healthy physiologic activity.

Abstract: A system and method for communicating data and signals through the Medical Implant Communication Service Band using a repeater or base station in the proximity to an implantable device within a patient is disclosed. In a preferred embodiment, the device is capable for early detection and monitoring of congestive heart failure in a patient. Impedance measurements, or other health parameters depending on the type of implantable device or sensor used, are sent using a bi-directional low-power radio operating in the MICS band to a nearby base station which may provide signal processing and analysis. The base station may have an interface to one or more communications networks to connect to a remote location. The system and method of the present invention permits a healthcare professional to monitor an ambulatory patient's condition at a remote location and to program the implanted device.

Abstract: A method and device for treating myocardial ischemia are described in which the stress experienced by a myocardial region identified as vulnerable to becoming ischemic is varied with pre-excitation pacing. In an unloading mode, pacing is applied in proximity to the vulnerable region to reduce stress and the metabolic demand of the region. In a loading mode, pacing is applied to a region remote from the vulnerable region in order to produce a conditioning effect.

Abstract: A pacing and sensing algorithm (800) which uses respiratory input to detect impending neurocardiogenic syncope is described. This algorithm (800), when used with conventional pacemakers, may be utilized to prevent recurrent syncope in patients with isolated recurrent neurocardiogenic syncope, as well in patients with established indications for pacemakers (e.g., conduction system disease, sudden cardiac death prophylaxis, cardiac resynchronization) and concurrent neurocardiogenic syncope.

Abstract: An exemplary method includes acquiring intrathoracic impedance values over one or more respiratory cycles, acquiring myocardial evoked response values and assessing cardiac condition based at least in part on the intrathoracic impedance values and the evoked response values. Other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: Methods and systems for diagnosing disorders, including, for example, disordered breathing, involve sensing one or more of a blood chemistry parameter and/or an expired gas parameter, such as expired respiratory gas concentration, blood gas concentration, and blood pH. Diagnosis of the disorder may be performed by a medical device, such as a respiratory therapy device or a cardiac therapy device, based on implantably detected blood gas/pH concentration/level or externally detected expired respiratory gas concentration. Cardiac and respiratory therapies for addressing the disorder may be adjusted based on the detected parameters.

Abstract: Methods and systems involve adjusting respiratory therapy based on cardiac cycle phase. A parameter indicative of cardiac cycle is sensed and the respiratory therapy is adjusted based on cardiac cycle phase. Modulation of respiratory therapy pressure reinforces the pumping action of the heart and results in increased cardiac output with decreased expenditure of myocardial energy output.

Abstract: A rate-adaptive pacemaker and a method for its operation in which the response factor for a minute ventilation sensor or other type of exertion level sensor is automatically set during a parameter adjustment mode that utilizes an activity level measurement to determine when the patient is at a target activity level with which is associated an appropriate target pacing rate. In a preferred embodiment, the target activity level corresponds to casual walking (e.g., 2 mph at a 4% grade) with a target pacing rate selected as appropriate for that level of activity in the individual patient.

Abstract: A method and apparatus for verifying a determined cardiac event in a medical device based on detected variation in hemodynamic status that includes a physiologic sensor sensing physiologic signals to generate a plurality of variation index samples corresponding to the sensed signals, and a microprocessor computing a variation index trend associated with a predetermined number of variation index samples of the plurality of variation index samples, determining whether deviations of the predetermined number of variation index samples over predetermined sampling windows are less than a deviation threshold, and determining, in response to the deviations being less than the deviation threshold, a corrected variation index trend in response to the changes in the variation index trend during the predetermined sampling windows.

Abstract: A maximum pacing rate limiter for use in adaptive rate pacing in conjunction with a cardiac rhythm management system for a heart. The maximum pacing rate limiter may function to measure an interval, termed the ERT interval, between a paced ventricular evoked response and a T-wave. The maximum pacing rate limiter may further function to maintain the ERT interval at less than a certain percentage of the total cardiac cycle. In one disclosed embodiment, a maximum pacing rate limiter calculates an ERT rate based on the detected paced ventricular evoked response and the T-wave, and the pacing rate limiter module further communicates the minimum of the ERT rate and an adaptive-rate sensor indicated rate to a pacemaker.

Abstract: A system and method of sensing relatively low magnitude signals of interest in a sensing environment with at least intervals of relatively high magnitude noise of comparable or overlapping frequency spectra as the signals of interest. The systems and methods can be implemented in an efficient, low-power manner to facilitate long term monitoring of low magnitude physiologic signals, for example in an in vivo or implantable manner. An amplifier can be arranged with a threshold detector driving a normally closed switch such that the input to or output from the amplifier can be opened when the noise exceeds a threshold. A filter, such as a moving average filter, can be included to smooth the amplified output and compensate for the amplified signal lost when the threshold is exceeded. The systems and method facilitate implantable nerve sensing in high noise environments, such as from myopotentials.

Abstract: An adaptive feed-back controlled system for regulating a physiological function of a heart in which a hemodynamic sensor continuously monitors the physiological performance of the heart. Three implanted electrodes sense and pace the right atrial, right ventricle and left ventricle. A learning neural network module receives and processes information for the electrodes (18) and sensors (22), and is controlled by a deterministic module for limiting said learning module. A pulse generator (16), is also controlled by the deterministic module, and stimulates both the heart and the vagus (20).

Abstract: Hemodynamic signals, such as photoplethysmography (PPG) signals, pressure signals, and impedance signals, are sampled once per cyclical body cycle to reduce the amount of data, processing and/or power required to analyze the hemodynamic signals.

Abstract: A medical device capable of delivering automatic rate-adjusting pacing therapies is provided having an adjustable upper rate limit responsive to an indication of myocardial irritability. The device, which may be embodied as a pacemaker, a pacemaker/cardioverter/defibrillator, or the like, responds to the detection of an arrhythmia as an indicator of myocardial irritability by adjusting an upper rate limit. The adjusted upper rate limit is applied as the maximum allowable pacing rate during delivery of any pacing therapies previously defined as “long-term” pacing therapies.

Abstract: An implantable cardiac stimulation device provides an intracardiac electrogram with reduced respiratory modulation effect. The device includes a sensing circuit that senses cardiac activity and provides an intracardiac electrogram signal extending over a plurality of cardiac cycles, a respiration monitor that monitors respiration associated with the sensed cardiac activity, and a cardiac cycle selector that selects a set of intracardiac electrogram cardiac cycles of the plurality of cardiac cycles in response to the monitored respiration. A processing circuit processes the selected set of intracardiac electrogram cardiac cycles to provide the intracardiac electrogram with reduced respiratory modulation effect.

Abstract: An approach to providing disordered breathing therapy includes providing therapy based on a prediction of disordered breathing. One or more patient conditions are detected and used to predict disordered breathing. Therapy is delivered to mitigate the predicted disordered breathing. The disordered breathing therapy may be adapted to enhance therapy efficacy and/or to reduce the impact of the therapy to the patient.

Abstract: An approach to providing disordered breathing therapy includes delivering electrical stimulation therapy modifying a patient's baroreflex response. Disordered breathing therapy may be delivered in response to prediction or detection of disordered breathing events. Various conditions affecting the patient may be evaluated and the baroreflex therapy modified. The therapy may be modified to improve therapy efficacy, to reduce an impact to the patient and/or to mitigate therapy interactions.

Abstract: An exemplary method includes delivering stimulation according to one or more stimulation parameters to cause contraction of the diaphragm, monitoring chest activity related to respiration and, in response to the monitoring, adjusting one or more of the one or more stimulation parameters during contraction of the diaphragm and continuing the delivering. Various other exemplary methods, devices, systems, etc., are also disclosed.

Abstract: The present invention is related to implantable cardiac devices such as pacemakers and defibrillators that deliver cardiac resynchronization therapy (CRT), and to a method of optimizing acquisition of impedance signals between electrodes present on implanted lead systems. This system then automatically determines which electrodes or electrode combinations acquire impedance waveforms that have the best signal to noise ratio (highest fidelity) and characterize data most representative of dysynchronous electro-mechanical events. Using closed loop algorithms which provide electrograms and a variety of impedance data reflective of the patient's clinical status, the system autonomously modifies interval timing within the CRT device.

Abstract: A method and system for improving or optimizing the collection of data from and the delivery of therapy to a patient by an implantable medical device (IMD) is disclosed which uses information about the patient's respiratory cycle.

Abstract: Calibration of adaptive-rate pacing by a cardiac rhythm management system using an intrinsic chronotropic response. The cardiac rhythm management system may include an adaptive-rate pacing device. The adaptive-rate pacing device may include an adaptive-rate sensor module for measuring an activity level of the individual. A monitor module may be coupled to the adaptive-rate sensor module, the monitor module monitoring an intrinsic chronotropic response. A calculator module may be coupled to the monitor module, the calculator module calculating a calibrated parameter for the adaptive-rate pacing device based on the intrinsic chronotropic response. An adjuster module may be coupled to the calculator module, wherein the adjuster module adjusts the adaptive-rate pacing device based on the calibrated parameter. The parameters of the adaptive-rate pacing device adjusted by the adjuster module may include a sensor rate target, a maximum sensor rate, and a response factor.

Abstract: Adaptive rate pacing for improving heart rate kinetics in heart failure patients involves determining onset and sustaining of patient activity. The patient's heart rate response to the sustained activity is evaluated during a time window defined between onset of the activity and a steady-state exercise level. If the patient's heart rate response to the sustained activity is determined to be slow, a pacing therapy is delivered at a rate greater than the patient's intrinsic heart rate based on a profile of the patient's heart rate response to varying workloads. If determined not to be slow, the pacing therapy is withheld. Monitoring-only configurations provide for acquisition and organization of physiological data for heart failure patients. These data can be acquired on a per-patient basis and used to assess the HF status of the patient.

Abstract: Various aspects relate to an implantable device. Various device embodiments comprise at least one pulse generator and a controller to communicate with the pulse generator(s). The pulse generator(s) is (are) adapted to deliver a first electrical signal through at least one electrode positioned proximate to a vagus nerve and to deliver a second electrical signal through at least one electrode positioned within or proximate to the heart. The controller includes a module to provide epilepsy therapy that includes delivering the first electrical signal though the at least one electrode proximate to the vagus nerve and a module to provide a cardiac rhythm management (CRM) therapy that includes delivering the second electrical signal through at least one electrode positioned within or proximate to the heart. The CRM therapy includes at least one therapy selected from an antitachycardia therapy and a cardiac resynchronization therapy (CRT). Other aspects and embodiments are provided herein.

Abstract: A method of providing cardiac stimulation therapy and a device for providing the therapy. A patient's cardiac activity as well as cyclical respiration is monitored. Cardiac stimulation is provided as indicated as therapeutic intervention for a variety of cardiac arrhythmias according to variable timing parameters. One or more of the timing parameters under which cardiac pacing stimulations are provided is varied or modulated with the cyclical variations in respiration. The one or more timing parameters are generally shortened or elongated in concert with the alternating inspiration/exhalation phases of respiration. In certain implementations, the patient's respiration is inferred from cardiac based physiologic signals. The methods and devices for providing cardiac stimulation therapy more accurately emulate natural healthy physiologic activity.

Abstract: Lead Tracking of Implantable Cardioverter-Defibrillator and Cardiac Resynchronization Therapy Devices improve upon the process of implantation of ICD-CRT devices, placing their leads, and improving the information fed back to the device and/or clinician. Tracking of the placement of the leads during implantation is accomplished along with monitoring the leads once implanted. Benefits include reducing the risk and complication rate, simplifying implantation procedure, and enabling the extraction of vital data not previously available. Leads are tracked to at least minimize the need to use fluoroscopy. Three dimensional tracking (10) is employed to facilitate obtaining of data that allows the surgeon to better visualize lead insertion and placement. Placement of the leads during a procedure requires use of an external tracking component along with means and method for tracking the implantable leads.

Abstract: An adherent device is configured to adhere to the skin of the patient with an adherent patch, for example breathable tape, coupled to at least four electrodes. The device comprises impedance circuitry coupled to the at least four electrodes and configured to measure respiration of the patient to detect sleep apnea and/or hypopnea. The impedance circuitry may be used to measure hydration of the patient. An accelerometer can be mechanically coupled to the adherent patch such that the accelerometer can be coupled to and move with the skin of the patient. Electrocardiogram circuitry to generate an electrocardiogram signal may be coupled to at least two of the at least four electrodes to detect the sleep apnea and/or hypopnea.

Abstract: Methods and devices for producing respiratory sinus arrhythmia in a subject are provided. Aspects of the invention include electrically stimulating or sensing motion of the diaphragm, and electrically stimulating the heart in a subject in a manner effective to produce respiratory sinus arrhythmia. The methods and devices find use in a variety of applications, e.g. in the treatment of subjects suffering from heart failure conditions.

Abstract: Heart rate information is used at least in part to obtain one or more parameters for inducing respiration. In various implementations, respiratory parameters, such as a target breathing rate or a target tidal volume may be delivered by an implantable device to a patient during periods of altered respiration, such as sleep apnea or exercise. A respiratory parameter may also be obtained from a physiological variable, a patient's physical activity level, or metabolic demands.

Abstract: The present invention describes a method of tracking minute ventilation from R-R intervals that are based on the acquisition of ECG signal. Sub-methods (RDF1), which are mainly based on heart rate variability, are used, wherein the respiratory frequency is determined from a pattern of rhythmic changes in heart beat data. The sub-methods (RDF1-n) are combined using an expert function, wherein each sub-method (RDF1-n) determines an estimate of the respiratory frequency.

Abstract: Methods and devices for reducing phrenic nerve stimulation of cardiac pacing systems involve delivering a pacing pulse to a ventricle of a heart. A transthoracic impedance signal is sensed, and a deviation in the signal resulting from the pacing pulse may be used to determine phrenic nerve stimulation. Methods may further involve detecting the phrenic nerve stimulation from the pacing pulse by delivering two or more pacing pulse to the ventricle of the heart, and determining a temporal relationship. A pacing vector may be selected from the two or more vectors that effects cardiac capture and reduces the phrenic nerve stimulation. A pacing voltage and/or pulse width may be selected that provides cardiac capture and reduces the phrenic nerve stimulation. In other embodiments, a pacing pulse width and a pacing voltage may be selected from a patient's strength-duration curve that effects cardiac capture and reduces the phrenic nerve stimulation.

Abstract: A system and method are described for automatically detecting diaphragmatic stimulation (DS) based on evoked response signals, electrogram data and/or thoracic impedance measurements. In addition, several optional modalities are described to circumvent this problem and alleviate symptoms related to DS while preserving LV pacing.

Abstract: A device and method is provided for biasing lung volume by electrically stimulating tissue associated with the diaphragm or phrenic nerve at a low level.