Abstract: Methods, systems, and devices for signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In illustrative examples, captured data including detected events is analyzed to identify likely overdetection of cardiac events. In some illustrative examples, when overdetection is identified, data may be modified to correct for overdetection, to reduce the impact of overdetection, or to ignore overdetected data. New methods for organizing the use of morphology and rate analysis in an overall architecture for rhythm classification and cardiac signal analysis are also discussed.

Abstract: Methods, systems, and devices for signal analysis in an implanted cardiac monitoring and treatment device such as an implantable cardioverter defibrillator. In some examples, captured data including detected events is analyzed to identify likely overdetection of cardiac events. In some illustrative examples, when overdetection is identified, data may be modified to correct for overdetection, to reduce the impact of overdetection, or to ignore overdetected data. Several examples emphasize the use of morphology analysis using correlation to static templates and/or inter-event correlation analysis.

Abstract: This document describes, among other things, systems and methods for characterizing a tachyarrhythmia. A method comprises obtaining a current first primary characterization of the tachyarrhythmia and a current first primary confidence level of the current first primary characterization, obtaining a current second primary characterization of the tachyarrhythmia and a current second primary confidence level of the current second primary characterization, and determining a current secondary characterization using the current first primary characterization, the current first primary confidence level, the current second primary characterization, and the current second primary confidence level.

Abstract: An implantable medical device senses a plurality of electrograms from substantially different atrial locations, detects regional depolarizations from the electrograms, and analyzes timing relationships among the regional depolarizations. The timing relationships provide a basis for effective therapy control and/or prognosis of certain cardiac disorders. In one embodiment, an atrial activation sequence is mapped to show the order of occurrences of the regional depolarizations during an atrial depolarization for classifying a detected tachyarrhythmia by its origin. In another embodiment, conduction time between two atrial locations is measured for monitoring the development of an abnormal atrial conditions and/or the effect of a therapy.

Abstract: Electrocardiologic device for assisted diagnosis, preferably for the diagnosis of Brugada syndrome or Early Repolarization syndrome. This device allows characterizing the ventricular repolarization wave of an ECG signal collected from a patient. Extracting out of the ECG signal, for each heart beat, an ST segment is constituted of a succession of samples of the ventricular repolarization wave, taken within a time window ([QON+80 ms, QON+140 ms]) of a predetermined duration spreading from a moment of window onset defined by a time offset applied to a predetermined temporal origin given by the moment (QON) of appearance of the QRS complex, whose time position is determined on the ECG signal for each heart beat. Quantizing computes an elevation index compared to a predetermined reference level (BL), and analyzing over a succession of heart beats the persistence and/or variation of this elevation index.

Abstract: Exemplary systems and methods for automatically managing implantable medical device (IMD) related alerts are described. One method receives implantable medical device-related alerts. The method automatically manages the implantable medical device alerts by parsing the alerts through a set of predefined parameters.

Abstract: An apparatus comprises an implantable cardiac signal sensing circuit and a controller circuit. The implantable cardiac signal sensing circuit provides a sensed depolarization signal from a ventricle and a sensed depolarization signal from an atrium. The controller circuit includes an onset detection circuit and a classification circuit. The onset detection circuit detects an onset episode that includes fast cardiac depolarizations and identifies a depolarization that initiates the onset episode.

Abstract: A system and method determining physiological status of a patient. A determination is made whether the patient is sleeping. The amplitude and change in voltage over time of any intramyocardial electrogram is measured for a right ventricle and a left ventricle of a heart of the patient for a predefined number of heartbeats at a specified time interval in response to determining the patient is asleep. The measurements are averaged for the right ventricle and left ventricle. The averaged measurements are transmitted to a receiver for communication to an intended recipient.

Abstract: Systems and method for assessing a likelihood of a patient having a heart to experience a cardiac arrhythmia. A sensor is configured to detect a premature ventricular contraction of the heart, the premature ventricular contraction being premature relative to a rate of ventricular contractions during a period preceding the premature ventricular contraction. A processor is configured to determine a dispersion of a predetermined number of repolarizations of the heart of the patient occurring following the premature ventricular contraction of the heart if a compensatory pause is detected in conjunction with the premature ventricular contraction, then determine the likelihood of the patient experiencing the cardiac arrhythmia based, at least in part, on the dispersion of the plurality of repolarizations of the heart of the patient.

Abstract: A system for heart performance characterization and abnormality detection processes a heart electrical activity signal in determining multiple first signal characteristic values over multiple heart cycles. A first signal characteristic value substantially comprises a time interval between a peak of a P wave to a peak of a succeeding R wave representing a repolarization time interval in an individual heart cycle and the signal processor uses a peak detector and time detector for identifying the peaks and detecting a time difference between the identified peaks. A comparator compares at least one of the multiple first signal characteristic values or a value derived from the multiple first signal characteristic values with a threshold value to provide a comparison indicator. A patient monitor in response to the comparison indicator indicating a calculated signal characteristic value exceeds the threshold value, generates an alert message associated with the threshold.

Abstract: Electrocardiogram (ECG) recorded signals are processed by a computer-implemented method to substantially remove extraneous signals to produce intermediary signals, and to separate the intermediary signals using a non-orthogonal transformation method such as independent component analysis to produce independent components of signals. The separated signals are displayed to help physicians to analyze medical conditions and to identify locations of abnormal heart conditions.

Abstract: Electrocardiogram data is received in association with a subject, the electrocardiogram data comprising a series of RR intervals and a series of QT intervals. A first value which indicates an amount by which uncertainty associated with the QT intervals is reduced given the RR intervals is generated. A second value which indicates an amount by which uncertainty associated with the RR intervals is reduced given the QT intervals is generated. The subject is determined to be associated with a low risk of cardiac dysfunction responsive to the first value exceeding the second value and a result of the determination is provided.

Abstract: An implantable medical device, is designed to collect a signal representative of the electric activity of the heart and determine a cardiogenic impedance signal for at least a portion of the heart. An R-wave detector of the IMD detects the timing of an R-wave during a cardiac cycle based on the signal representative of the electric activity. A minimum detector detects the timing of a cardiogenic impedance minimum in the cardiogenic impedance signal and within a systolic time window of the cardiac cycle. A detected arrhythmia is then classified by the IMD based on the timing of the R-wave detected by the R-wave detector and the timing of the cardiogenic impedance minimum detected by the minimum detector.

Abstract: In a subcutaneous implantable cardioverter/defibrillator, cardiac arrhythmias are detected to determine necessary therapeutic action. Cardiac signal information is sensed from far field electrodes implanted in a patient. The sensed cardiac signal information is then amplified and filtered. Parameters such as rate, QRS pulse width, cardiac QRS slew rate, amplitude and stability measures of these parameters from the filtered cardiac signal information are measured, processed and integrated to determine if the cardioverter/defibrillator needs to initiate therapeutic action.

Abstract: Apparatus and method for detecting and filtering noise artifacts by analysis of a cardiac vectogram is disclosed. An active medical device collects electrical activity signals of a patient's heart over a series of cardiac cycles. At least two distinct temporal components (Vbip, Vuni) are obtained from at least two endocardial electrogram (EGM) signals that are collected concurrently on different respective channels from the same heart cavity.

Abstract: A heart monitor for processing input signals that represent periodically reoccurring events in a sequence of heart cycles. According to the invention graphical data representing a scatter plot of at least two dimensions, one dimension representing interval duration or its inverse and the other dimension representing change of duration or its inverse, respectively, are generated. The scatter plot comprises data points of which each data point represents heart interval duration or its inverse plotted against the change of duration with respect to a neighboring interval or the inverse of said change respectively.

Abstract: An intracardiac electrogram (IEGM) or other suitable electrical cardiac signal is sensed. Values representative of a pre-symptomatic physiologic response to a hypoglycemic event are derived from the cardiac signal. Then, hypoglycemia is detected based on the values representative of the pre-symptomatic physiologic response. In one example, both temporal morphological parameters and spectral parameters affected by pre-symptomatic hypoglycemia are derived from the cardiac signal. Hypoglycemia is then detected based on a combination of the temporal and spectral parameters using, e.g., a linear discriminator. By detecting hypoglycemia based on parameters affected by pre-symptomatic hypoglycemia, suitable warnings can be generated and therapies initiated before the condition becomes symptomatic.

Abstract: A method for evaluating electrocardiogram QT interval-prolonging action of a test substance, which comprises preparing a hamster anesthetized under such a condition that end of T wave is definitely observed on an electrocardiogram, and comparing electrocardiogram QT intervals of the hamster observed before and after administration of the test substance to evaluate electrocardiogram QT interval-prolonging action of the test substance.

Abstract: The present invention relates to a system or method for analyzing drug influence on ECG curvature and Long QT Syndrome. The system has an input means connected to an ECG source, where different parameters of a received ECG curvature are indicated and/or isolated for indicating possible symptoms which relate to certain diseases that influence the ECG curvature. The aim of the invention is to achieve a system and a method for diagnosing Long QT Syndrome in an objective, fast and effect way by indication of a number of symptoms derivable from an ECG curve. Further aim is to achieve an effective test of drug influence on ECG curvature. The system analyzes the QT curvature of the ECG curvature for indicating Long QT Syndrome.

Abstract: A method and apparatus for detecting a cardiac event in a medical device that includes sensing cardiac signals from a plurality of electrodes forming a first sensing vector and a second sensing vector, advancing from a first state to a second state in response to processing of an interval associated with a cardiac cycle of the sensed cardiac signals, and advancing from the second state in response to processing of a cardiac signal sensed during a predetermined sensing window.

Abstract: Template formation methods for use in implantable cardiac rhythm management devices. In an illustrative method, a signal is captured in an implanted cardiac rhythm management device, and parameters for analysis of the captured signal are then defined. Then, in the example, additional signals can be captured and used to either verify or discard the captured signal defined parameters. The template formation methods provide for creating a robust template to compare with sensed cardiac complexes. Devices and systems configured to perform template formation and verification methods are also shown.

Abstract: In an apparatus and method for detecting incipient heart failure of a patient. Impedance signals reflecting volume changes of the right ventricle and/or the right atrium of a heart of the patient are obtained. The impedance signals are processed to determine a first impedance parameter substantially reflecting a volume of the right ventricle, and a heart failure status is determined based on the first impedance parameter, wherein a decreasing first impedance parameter is determined to be an indication of a deterioration of the heart failure status.

Abstract: A PC-based ECG software program that in real time, acquires, analyzes and displays QTV and PQ interval variability (PQV) in each of the independent channels that constitute the 12-lead conventional and/or Frank X, Y, Z lead ECG. The system also analyzes and displays the QTV and PQV from QT and PQ interval signals that are derived from multiple channels and from singular value decomposition such that the effect of noise and other artifacts on the QTV and PQV results are substantially reduced compared to existing single-channel methods. Moreover, this invention also provides certain new parameters of T-wave (and QRS and P-wave) morphology, that in initial studies have improved clinical diagnostic utility and/or reproducibility and reliability compared to known existing parameters of T-wave morphology. Finally, it also provides a method for determining the beat-to-beat variability these T, QRS and P-wave morphologic parameters.

Abstract: A device and method for delivering electrical stimulation to the heart in a manner which provides a protective effect against subsequent ischemia is disclosed. The protective effect is produced by configuring a cardiac pacing device to intermittently switch from a normal operating mode to a stress augmentation mode in which the spatial pattern of depolarization is varied to thereby subject a particular region or regions of the ventricular myocardium to increased mechanical stress.

Abstract: Disclosed is an apparatus and method for ambulatory, real-time detection of Atrial Fibrillation (AF) providing an overall accuracy that refers to detection of AF, irrespective of the duration of AF and beat-to-beat classification.

Abstract: Techniques are provided for detecting atrial fibrillation (AF) based on variations in ventricular intervals detected by a pacemaker, implantable cardioverter-defibrillator (ICD) or implantable cardiac monitor (ICM). In one example, ventricular beats are detected and intervals between the ventricular beats are measured, such as RR intervals. Irregular ventricular beats are identified, including ectopic beats, bigeminal beats, and the like. The degree of variability within the ventricular intervals is then determined while excluding any intervals associated with irregular beats. AF is then detected based on the degree of variability. That is, AF is detected based on variability occurring within ventricular intervals after ectopic beats and other irregular beats have been eliminated, thus mitigating detection problems that might arise if the variability were instead calculated based on all ventricular beat intervals.

Abstract: The invention is a wireless sensor system coupled with sensors to non-invasively monitor external stimuli. By monitoring the outputs of sensors, the output data can be used to activate an alarm or logged for further diagnoses of human conditions.

Abstract: A method and system is provided for responding, from internally within a patient, to an atrial arrhythmia in a heart including measuring from within the patient at least one electrocardiogram characteristic indicative of the atrial arrhythmia, and controlling from within the patient drug therapy delivery to the patient responsive to measuring the at least one electrocardiogram characteristic. Drug therapy is initiated to the patient responsive to measuring the at least one electrocardiogram characteristic. According to one aspect of the present invention, the drug therapy is staged within the patient prior to measuring the at least one electrocardiogram characteristic. According to another example embodiment, the heart is paced from within the patient at a predefined rate responsive to measuring the at least one electrocardiogram characteristic, pacing occurring alone, or in combination with drug therapy.

Abstract: An implantable medical device monitors ST segment data collected from EGM. ST trends are established and monitored over time. The IMD is able to discern whether the data indicate supply ischemia, demand ischemia, or other physiological causes. The IMD is then able to provide appropriate information and alerts.

Abstract: An ECG monitoring system continuously monitors a patient's ECG waveform and periodically identifies the patient's QT interval. QT interval values are averaged over time and a corrected interval value QTc and a change in QTc relative to a baseline, dQTc, are periodically produced. An alarm is responsive to updated QT interval values and issues an alarm whenever a selected QT value exceeds an alarm limit. The periodically produced QT interval values are stored and a trend display may be produced showing changes in the QT interval information over different periods of time. The trend display may selectively display the trend information either graphically or in tabular form.

Abstract: A system and method for triggering an external device in response to an electrocardiogram signal. In one embodiment the method includes determining a peak in the electrocardiogram signal, determining if the electrocardiogram signal is rising or falling at the peak in the signal and triggering a device in response to the rising or falling peak. In one embodiment of the invention an external trigger signal is produced only a rising peak is detected. In one embodiment, the system includes a microprocessor, a peak detector and a trigger circuit. The trigger circuit outputs a trigger signal to an external device when signaled by the peak detector and not inhibited by a signal from the microprocessor.

Abstract: The RR series, comprising a number of samples respectively defining the time interval between two successive heartbeats, is filtered by means of a digital band-pass filter (Fk), having a given band-pass [fc; f?c] and preferably by means of a recursive elective filter (RII). A variability index (Ik), is calculated which is a function of the instantaneous amplitude [vs(n)] of the discrete signal (Sk) coming from said band-pass filter. The variability index (Ik) is preferably a function of and particularly equal to the effective value of the discrete signal (Sk) from the band-pass filter.

Abstract: A method comprising sensing at least one cardiac signal representative of cardiac activity of a subject using an implantable medical device (IMD), calculating, from the cardiac signal, a first dominant vector corresponding to a direction and magnitude of maximum signal power of an ST-T first segment of a cardiac cycle and a second dominant vector corresponding to a direction and magnitude of maximum signal power of a P-QRS second segment of a cardiac cycle, measuring a change in the first dominant vector, measuring a change in the second dominant vector, and subtracting the change in the second dominant vector from the measured change in the first dominant vector to form a difference.

Abstract: A system for analyzing an ECG signal is provided. The system comprises an interface that receives an ECG waveform associated with heart beat cycle of a patient. The system includes signal processor that determines a first isoelectric portion lying between a T-wave of a first heart beat cycle and a P-wave of a successive heart beat cycle, and a second isoelectric portion lying between a P-wave and a QRS complex of the first heart beat cycle. The signal processor determines a stability measure for each of said first and second portions and adaptively selects the first or the second portion as a baseline for the first heart beat cycle based on the stability measures. The signal processor determines a point of reference on an ST segment associated with the first heart beat cycle and evaluates a deviation of the point of reference on the ST segment from the selected baseline.

Abstract: A method and system for automatically determining ischemia detection parameters are provided. The method includes obtaining a baseline trace indicative of a cardiac behavior, determining an ischemia detection window based on at least one physiologic state indicator within the baseline trace, and automatically identifying a fiducial point based on the baseline segment trace. The baseline trace includes a baseline segment within the ischemia detection window; where the ischemia detection window and the fiducial point may constitute ischemia detection parameters.

Abstract: This document discusses, among other things, a system including an implantable medical device. The implantable medical device includes a control circuit and a motion sensing device. The motion sensing device is coupled to the control circuit, and the motion sensing device is configured to transmit signals to the control circuit. The control circuit is configured to identify one or more steps of a patient using the motion sensing device signal.

Abstract: Systems and Methods for stratifying relative risks of adverse cardiac events by processing a duration of electrocardiograph recordings generally recorded by a Holter type of device. The duration of electrocardiograph recordings are processed to resolve RR interval related data, QT interval related data, and are fitted to formulas to at least partially establish fitting related measures. The fitting formulas incorporate circadian related periodic factors, and can further incorporate additional processing including utilizing Lissajous analysis techniques, among others.

Abstract: An implantable medical device and associated method for automatically generating morphology templates during fast cardiac rhythms, confirming a provisional template as a confirmed template, and using the confirmed template to classify subsequent detected arrhythmias. A provisional SVT template may be created during a fast ventricular rate and activated as a confirmed SVT template upon verification that the fast rate was due to an SVT. The confirmed SVT template may be used to discriminate SVT from VT/VF.

Abstract: A method and system for setting the operating parameters of a cardiac rhythm management device in which a plurality of parameter optimization algorithms are available. A measured feature of an electrophysiological signal such as QRS width has been shown to be useful in selecting among certain parameter optimization algorithms. In one embodiment, one or more resynchronization pacing parameters are set based on one or both of the feature extracted from an electrogram signal and the value of a resynchronization pacing parameter which tends to minimize the intrinsic atrial rate.

Abstract: A morphology discrimination scheme extracts shape characteristics from cardiac signals and identifies an associated cardiac condition based on the shape characteristics. For example, internal data structures may be updated to match the shape characteristics of a known condition (e.g., a patient's normal sinus rhythm). Similarly acquired shape characteristics obtained in conjunction with a later event (e.g., QRS complexes acquired during a tachycardia episode) may be compared with the previously stored shape characteristics to characterize the later event. In some aspects the shape characteristics relate to inflection points of cardiac signals.

Abstract: Estimating a frequency of a sampled cardiac rhythm signal and classifying the rhythm. The received signal is sampled and transformed into a curvature series. A lobe in the curvature series corresponds to a characteristic point in the sampled series. Characteristic points are selected based on a time of a lobe in the curvature series and, in one embodiment, an amplitude of the signal at the time of the lobe. A frequency of the sampled series is estimated by autocorrelating a function of the series of the characteristic points. In one embodiment, the function is a time difference function. The rhythm is classified by plotting the timewise proximity of characteristic points derived from an atrial signal with characteristic points derived from a ventricular signal. Regions of the plot are associated with a particular rhythm and the grouping of the data corresponds to the classification.

Abstract: An implanted cardiac rhythm management device is disclosed that is operative to detect myocardial ischemia. This is done by evaluating electrogram features to detect an electrocardiographic change; specifically, changes in electrogram segment during the early part of an ST segment. The early part of the ST segment is chosen to avoid the T-wave.

Abstract: Implantable systems that can monitor myocardial electrical stability, and methods for use therewith, are provided. Also provided are novel pacing sequences that are used in such monitoring. Such pacing sequences are designed to reveal alternans at low to moderate heart rates.

Abstract: A method for operating a cardiac rhythm management device in which a clinical state vector is computed as a combination of a plurality of parameters related to a patient's heart failure status and compared to a previously computed clinical state vector to determine a clinical trajectory indicative of changes in the patient's heart failure status. Such detected changes in status can be used both as a clinical tool to evaluate treatment and to automatically adjust the operation of the device.

Abstract: A ventricular rate based on first candidate waveforms and second candidate waveforms within sensed ventricular waveforms is compared to an atrial rate. If the ventricular rate exceeds the atrial rate, the first candidate waveforms and second candidate waveforms are compared to a ventricular polarization complex template to obtain a first morphology indicator and a second morphology indicator. If a morphology match inconsistency is present, the amount by which the ventricular rate exceeds the atrial rate is compared to a threshold. If the threshold is exceeded, high-ventricular-rate therapy to the heart is inhibited. The ventricular polarization complex template may be a QRS-complex template, in which case a match inconsistency is present if each of the first candidate waveforms and the second candidate waveforms do not match the QRS-complex template.

Abstract: A method of detecting a cardiac event in a medical device that includes determining a first characteristic in response to cardiac signals sensed along a first sensing vector over a predetermined sensing window and in response to cardiac signals sensed along a second sensing vector over the predetermined sensing window, determining a second characteristic in response to cardiac signals sensed along the first sensing vector over the predetermined sensing window and in response to cardiac signals sensed along the second sensing vector over the predetermined sensing window, and determining a third characteristic in response to cardiac signals sensed along the first sensing vector over the predetermined sensing window and in response to cardiac signals sensed along the second sensing vector over the predetermined sensing window.

Abstract: An exemplary method to reduce risk of ventricular oversensing includes sensing, in vivo, amplitude of electrical cardiac activity, comparing sensed amplitude to a low sensitivity threshold where if the comparing indicates that sensed amplitude does not meet or exceed the low sensitivity threshold then further comparing the sensed amplitude to a high sensitivity threshold and if the further comparing indicates that sensed amplitude meets or exceeds the high sensitivity threshold then determining that ventricular fibrillation may exist. Various exemplary devices, systems, methods, etc., are disclosed.

Abstract: Techniques are described for efficiently detecting and distinguishing among cardiac ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. In one example, a preliminary indication of an episode of cardiac ischemia is detected based on shifts in ST segment elevation within the IEGM. In response, the implanted device then records additional IEGM data for transmission to an external system. The external system analyzes the additional IEGM data to confirm the detection of cardiac ischemia using a more sophisticated analysis procedure exploiting additional detection parameters. In particular, the external system uses detection parameters capable of distinguishing hypoglycemia, hyperglycemia and hyperkalemia from cardiac ischemia, such as QTmax and QTend intervals. Alternatively, the more sophisticated analysis procedure may be performed by the device itself, if it is so equipped. Other examples described herein pertain instead to the detection of atrial fibrillation.

Abstract: The invention relates to a device for predicting tachyarrhythmias and/or atrial arrhythmias with recording means that record electric cardiac signals of a heart and with evaluating means that evaluate the recorded electric cardiac signals. In order to transmit the recorded cardiac signals to the evaluating means, the recording means are connected to the evaluating means. The device also comprises time means (5) that furnish circadian time signals, whereby associated circadian time signals which are assigned to the recorded electric cardiac signals and/or other electric cardiac signals, which are derived from the recorded electric cardiac signals. The inventive device also comprises memory means (6), which are coupled to the evaluating means (4) and which contain normal circadian cardiac data and/or other normal circadian cardiac data, and comprises output means (7), which are coupled to the evaluating means (4) and which transmits electric reaction signals.

Abstract: An apparatus and a method for detecting cardiac atrial fibrillation events in an EKG signal. The method comprises the steps of detecting a portion of an EKG signal comprising cardiac beats; measuring the duration of a gap in the detected portion of the EKG signal; and computing two or more inter-beat intervals. The computed interval is outputted if the gap in the portion of the EKG signal is not more than a fraction alpha of the computed interval. The method further includes the steps of computing the variance of the inter-beat intervals and classifying the portions of the EKG signal as indicative of an atrial fibrillation event. During classification, the inter-beat interval variance of the portion of the EKG signal that exceeds a pre-determined value V is indicative of an atrial fibrillation event.