Abstract: A system for analyzing cardiac electrophysiological signals includes an acquisition processor for acquiring signal data representing heart electrical activity over multiple heart cycles. An individual heart cycle comprises a signal portion between successive sequential R waves. A time interval detector uses a signal peak detector for detecting multiple successive time intervals including individual time intervals comprising a time interval between a first peak occurring in a first heart cycle and a second peak occurring in at least one of, (a) a successive sequential second heart cycle and (b) a third heart cycle successive and sequential to the second heart cycle. A data processor processes the multiple detected successive time intervals by, determining at least one interval parameter of, a mean, variance and standard deviation of the time intervals and generating an alert message in response to the interval parameter.

Abstract: A system and method for evaluating cardiovascular performance in real time and characterized by conversion of a surface potential into multi-channels are introduced. The system includes an electrocardiographic signal measuring unit, a reconstruction unit, and a parameter computation and assessment unit. The reconstruction unit reconstructs electrocardiographic signals (ECG signals) recorded by the electrocardiographic signal measuring unit, such that the ECG signals are reconstructed as ones located at different spatial positions but actually not having a channel. The method includes calculating a variation manifested spatially during an interval between a Q wave and a T wave of an ECG signal against time with a parameter computation and assessment algorithm, to evaluate its discreteness degree and thereby diagnose cardiovascular diseases (CVD) and locate lesions thereof.

Abstract: Cardiac activity is sensed over a plurality of heart beats defining a beat set. For each beat in the set, it is determined whether the beat is a non-classified beat (e.g., paced beat, a beat outside of a specified heart rate range or a PVC), or a classified beat. For each classified beat, it is determined whether the beat is a non-detect beat, a minor beat or a major beat. Counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats are maintained. The beat set is declared to be one of a non-classified set, a major set, a minor set or a non-detect set based on the relative counts of classified beats, non-classified beats, major beats, minor beats, and non-detect beats. Over a period of time, counts of beat-set types are maintained and entry into and exit from ST episodes are determined based on these beat-set counts.

Abstract: A method of analyzing myocardial instability includes obtaining a physiological parameter representative of myocardial behavior over a set of cardiac cycles and determining reversal points in the physiological parameter over the set of cardiac cycles. The method also includes identifying myocardial instability based on the reversal points in the physiological parameter. A reversal point may correspond to a value of the physiological parameter, during a current cardiac cycle, that exceeds or is less than the values of the physiological parameter during prior and subsequent cardiac cycles. Optionally, the method includes calculating differences between values of the physiological parameter for consecutive cardiac cycles and detecting the reversal points when a current difference exceeds or is less than differences for prior and subsequent cardiac cycles.

Abstract: A patient QRS duration can be received or determined, such as using one or more patient physiological sensors. A portion of the QRS duration can be determined, such as a right or left ventricular activation time. In an example, the right ventricular activation time can be determined by identifying an onset of a QRS complex and an R-wave peak in the QRS complex. In an example, when the QRS duration exceeds a threshold duration, and the RV activation time does not exceed a second threshold duration, an indication of a cardiac conduction dysfunction can be provided, such as for discriminating between left bundle branch block and right bundle branch block.

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: In a living body inspection apparatus to inspect RLS (Restless Legs Syndrome), a pulse interval is obtained from a pulse wave signal, thereby performing a frequency analysis of the obtained pulse interval using CDM. From a result of the frequency analysis, the low frequency components ranging from 0.04 to 0.15 Hz and the high frequency components ranging from 0.15 to 0.4 Hz are extracted. A value of low frequency components (LF)/high frequency components (HF) is obtained as an index to which an amendment based on age is applied. It is then determined whether LF/HF is equal to or greater than a predetermined determination value indicating RLS. For example, it is determined whether LF/HF is equal to or greater than 0.65, which suspects RLS. It is determined whether a signal is accurately calculated which indicates an activity of autonomic nerve. A state of RLS is determined using LF/HF.

Abstract: A system for heart performance characterization and abnormality detection includes an interface for receiving sampled data representing an electrical signal indicating electrical activity of a patient heart over multiple heart beat cycles. A signal processor automatically, decomposes the received sampled data to multiple different subcomponent signals in the time domain. The signal processor associates individual decomposed subcomponents with corresponding different cardiac rotors and determined characteristics of the subcomponents indicating relative significance of the rotors in a cardiac atrial condition. A reproduction device provides data indicating the subcomponent characteristics indicating relative significance of the rotors in a cardiac atrial condition.

Abstract: A method of predicting ventricular arrhythmias includes receiving an electrical signal from a subject's heart for a plurality of heart beats, identifying characteristic intervals and heart beat durations of the electrical signal corresponding to each of the plurality of heart beats to provide a plurality of characteristic intervals with corresponding heart beat durations, representing dynamics of the plurality of characteristic intervals as a function of a plurality of preceding characteristic intervals and durations of corresponding heart beats over a chosen period time, assessing a stability of the function over the chosen period of time, and predicting ventricular arrhythmias based on detected instabilities in the dynamics of the characteristic intervals.

Abstract: A heart monitor is disclosed. The monitor computes ST segment deviations and stores the results in heart rate based histograms. Periodically, the monitor analyzes the histogram data to determine a normal range of ST deviation for a particular heart rate range. The monitor computes heart rate dependent ischemia detection thresholds based on the upper and lower boundaries of the normal range.

Abstract: The present disclosure is directed to the classification of cardiac episodes using an algorithm. In various examples, an episode classification algorithm evaluates electrogram signal data using a probabilistic ventricular oversensing algorithm. The algorithm may look at a plurality of factors weighing for and against a determination of ventricular oversensing. In some examples, the algorithm may also determine whether the cardiac episode includes atrial sensing issues.

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: Disclosed is an arrhythmia-diagnosing method and device for diagnosing arrhythmias, such as fibrillation or tachycardia. The arrhythmia-diagnosing method includes the following steps: measuring (a) the heart characteristic length, and the (b) frequency and (c) conduction velocity of the cardiac electrical wave; and (d) determining the occurrence or absence of an arrhythmia by using the three parameters measured in steps (a) to (c). With this invention, it is possible to predict and diagnose an electrical wave tornado, one of the causes of arrhythmia, by using a non-dimensional parameter, to identify patients at risk of death or brain death due to an arrhythmia and to reduce the mortality of patients suffering from arrhythmias significantly.

Abstract: An acute ischemia monitor is disclosed. The monitor, which includes an analog to digital convertor and a processor that performs beat detection, monitors the time course of a heart signal parameter, namely ST segment deviation, computed from an electrocardiogram. The device stores ST deviation statistics for multiple leads. For each lead, upper and lower ST deviation boundaries are computed. For each lead, current ST deviation values are compared with the statistical values to determine a metric indicative of the degree of abnormality of a current ST deviation value. The metric is equal to the difference between the current ST deviation value and the upper or lower boundary, normalized according to the dispersion of the ST deviation. Metrics from different leads are summed and compared to a threshold to determine whether the combined metric is indicative of a cardiac event.

Abstract: Systems and method for assessing a patient's myocardial electrical stability by pacing a patient's heart using a pacing sequence that includes at least two different types of pacing pulses. The pacing rate used is preferably only slightly above the patient's intrinsic heart rate. A degree of alternans, in a signal (e.g., IEGM or ECG) that is indicative of cardiac activity in response to the pacing sequence, is determined. The degree of alternans can be determined by comparing portions of the signal that are indicative of cardiac activity in response to the first type of pacing pulses to portions of the signal that are indicative of cardiac activity in response to the second type of pacing pulses. The patient's myocardial electrical stability is assessed based on the determined degree of alternans.

Abstract: Techniques are provided for use by implantable medical devices for controlling ventricular pacing, particularly during atrial fibrillation. In one example, during a V sense test for use in optimizing ventricular pacing, the implantable device determines relative degrees of variation within antecedent and succedent intervals detected between ventricular events sensed on left ventricular (LV) and right ventricular (RV) sensing channels. Preferred or optimal ventricular pacing delays are then determined, in part, based on a comparison of the relative degrees of variation obtained during the V sense test. In another example, during RV and LV pace tests, the device distinguishes QRS complexes arising due to interventricular conduction from QRS complexes arising due to atrioventricular conduction from the atria, so as to permit the determination of correct paced interventricular conduction delays for the patient. The paced interventricular conduction delays are also used to optimize ventricular pacing.

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: Disclosed herein are various embodiments of methods, systems and devices for detecting atrial fibrillation (AF) in a patient. According to one embodiment, a patient places his or her left and right hands around left and right electrodes and a hand-held atrial fibrillation detection device acquires an electrocardiogram (ECG) from the patient over a predetermined period of time such as, by way of example, one minute. After acquiring the ECG from the patient, the device processes and analyzes the ECG and makes a determination of whether the patient has AF. The device may further be configured to provide a visual or audio indication of whether the patient has AF, or does not have AF. The device may be employed in a health care provider's office without the need for complicated or expensive diagnostic equipment, and is capable of providing an on-the-spot and low-cost diagnosis of AF.

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: Described herein are implantable systems and devices, and methods for use therewith, that can be used to perform arrhythmia discrimination. A plurality of different sensing vectors are used to obtain a plurality of different IEGMs, each of which is indicative of cardiac electrical activity at a different ventricular region. The plurality of different IEGMs can include, e.g., an IEGM indicative of cardiac electrical activity at a first region of the patient's left ventricular (LV) chamber and an IEGM indicative of cardiac electrical activity at a second region of the patient's LV chamber. Additionally, the plurality of different IEGMs can further include an IEGM indicative of cardiac electrical activity at a region of a patient's right ventricular (RV) chamber. For each of the IEGMs, there is a determination of a corresponding localized R-R interval stability metric indicative of the R-R interval stability at the corresponding ventricular region. This can include, e.g.

Abstract: Embodiments of the present invention relate to implantable systems, and methods for use therein, that can detect T-wave alternans and analyze the detected alternans to provide information regarding cardiac instabilities and predict impending arrhythmias.

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: Methods and apparatus for determining a patient specific QT-RR curve. One embodiment of a method in accordance with the technology comprises providing electrophysiological data for a specific patient. The method can further include: (a) determining QT durations and RR values for a plurality of heart beats of the specific patient from the electrophysiological data; (b) ascertaining effective RR intervals for the plurality of heart beats by weight-averaging the RR values according to the equation Effective RRi=C×Effective RRi?1+(1?C)×[RRweighted], where C is a number between 0 and 1, and where RRweighted is based on an observed RRi value and a trend predicted RR value; and (d) finding a value Cf defined by a value of C where a curve fitted to the QT durations and the ascertained effective RR intervals is within a desired standard deviation.

Abstract: Techniques are provided for use by implantable medical devices for controlling ventricular pacing, particularly during atrial fibrillation. In one example, during a V sense test for use in optimizing ventricular pacing, the implantable device determines relative degrees of variation within antecedent and succedent intervals detected between ventricular events sensed on left ventricular (LV) and right ventricular (RV) sensing channels. Preferred or optimal ventricular pacing delays are then determined, in part, based on a comparison of the relative degrees of variation obtained during the V sense test. In another example, during RV and LV pace tests, the device distinguishes QRS complexes arising due to interventricular conduction from QRS complexes arising due to atrioventricular conduction from the atria, so as to permit the determination of correct paced interventricular conduction delays for the patient. The paced interventricular conduction delays are also used to optimize ventricular pacing.

Abstract: Systems and methods are provided for quantifying and providing indicia of ST-segment resolution in an electrocardiogram (ECG) signal. A receiver acquires an electrocardiogram (ECG) signal that includes an ST-segment. A processor processes the ECG signal to determine values for the ST-segment deviation relative to an isoelectric baseline. A user is allowed to provide a baseline signal to the processor. The processor responds to the baseline signal by marking a baseline ST-segment value corresponding to a baseline time. A user interface displays a linear graphical trend of variations in the measured ST-segment values relative to the baseline ST-segment value. In certain embodiments, the processor detects user-selected trigger events such as post-intervention ST deviation relative to the baseline time and the baseline ST-segment value, and provides indicia of the trigger event. In addition, or in other embodiments, a verbal annunciation of a percent ST-segment resolution is provided.

Abstract: A method, a system and an arrangement to predict at least one system event and a corresponding computer program and a corresponding machine-readable storage medium are configured so that the event is predictable because of trends in observables over a certain period before the occurrence of the events. The method, system and arrangement can be used in particular for patient-specific monitoring of patho-physiological changes but also in geophysical or abstract units such as population or economic systems in which the deviation from a defined normal condition is predicted.

Abstract: A system comprises a cardiac signal sensing circuit and a processor circuit. To detect a QRS duration, the processor circuit determines an isoelectric amplitude value of the cardiac signal segment, identifies a time where the cardiac signal segment amplitude deviates from the first isoelectric amplitude value by a specified threshold deviation value as a Q time, determines an isoelectric value time after the determined maxima and minima times that the cardiac signal segment returns to the same or a different isoelectric amplitude value, identifies a time that follows both the determined maxima and minima times and precedes the isoelectric value time as an S time, wherein the cardiac signal segment amplitude at the identified S time satisfies a specified amplitude change criterion from an isoelectric amplitude value, and determines a time duration of the QRS complex in the cardiac signal segment using the identified Q and S times.

Abstract: A method and a system for detection of an arrhythmia and discrimination between different types of arrhythmia to determine whether to administer an electric shock to the heart, the method comprising monitoring the electrical activity of a beating heart, selecting a number of heart beat intervals that will comprise an analysis segment; determining an instantaneous heart rate for each of the heart beat intervals with the segment; calculating the mean instantaneous heart rate for the segment; determining the variability of the instantaneous heart rates compared to a mean; using a linear combination of the mean and the non-linear value for comparison with a predetermined threshold to discriminate the type of arrhythmia to automatically decide if intervention is indicated.

Abstract: An electromedical implant, having a far-field electrocardiogram capturing unit for recording a far-field electrocardiogram signal, which is connected or can be connected to at least two electrodes for recording electric signals reflecting the curve of the far-field electrocardiogram of the right and left atria, a detection unit, which is designed to detect signal features characterizing atrial cardiac actions in an electrocardiogram signal, an averaging unit, which is connected to the recording unit and the detection unit and designed to generate an averaged P-wave signal in that the averaging unit averages a plurality of signal sections of the electrocardiogram signal associated with a particular detected atrial cardiac action, and an evaluation unit, which is connected to the averaging unit and designed to determine the duration of an averaged P-wave in the particular averaged P-wave signal.

Abstract: The invention disclosed includes a method and apparatus for calculation of T-wave alternas in electrocardiographic (ECG) signals; said method comprises the following method steps: (a) collecting and storing an ECG signal; (b) detecting each heartbeat T-wave in the ECG signal using an automatic detection and segmentation algorithm; (c) classifying said heartbeat T-wave as an even or odd heartbeat T-wave; (d) initializing said method by taking the first even and the first odd heartbeat T-wave as their respective initial average; (e) processing all the heartbeat T-waves in the ECG signal to generate an even heartbeat T-wave weighted average and odd heartbeat T-wave weighted average; and (f) calculating TWA using a distance metric between the even heartbeat weighted average and the odd heartbeat weighted average, said distance metric including curve matching Continuous Dynamic Time Warping (CDTW).

Abstract: Method and apparatus for computer enabled analysis of ECG (electro cardiographic) data by exploiting computerized three-dimensional spatial presentation of the measured data using vectors. A three-dimensional presentation of the human heart may be correlated with waveforms specific for standard ECG or derived ECG signals based on the dipole approximation of the heart electrical activity. Additional tools for analyzing ECG data are also provided which may be used to determine the time of cardiac electrical events, to select specific beats for automated cardiac interval determination, and to flag ECGs that have been evaluated by automated means but may benefit by human reading.

Abstract: Devices and methods for analyzing cardiac signal data. An illustrative method includes identifying a plurality of detected events and measuring intervals between the detected events for use in rate estimation. In the illustrative embodiment, a set of intervals is used to make the rate estimation by first discarding selected intervals from the set. The remaining intervals are then used to calculate an estimated interval, for example by averaging the remaining intervals.

Abstract: Exemplary techniques and systems for interpolating left ventricular pressures are described. One technique interpolates pressures within the left ventricle from blood pressures gathered without directly sensing blood pressure in the left ventricle.

Abstract: Determining an index for assessing cardiac function. In an embodiment, a method includes receiving ventricular pressure data during an invasive cardiac procedure, wherein the received pressure data includes a diastatic ventricular pressure value, a minimum ventricular pressure value, and a predefined fiducial marker pressure value. An index value is calculated by comparing a first pressure difference to a second pressure difference. The first pressure difference represents the difference between the received diastatic ventricular pressure value and the received minimum ventricular pressure value. The second pressure difference represents the difference between the received fiducial marker pressure value and the received minimum ventricular pressure value. The index value is provided to a health care provider to assess early diastolic cardiac function.

Abstract: A medical device performs a method to classify a cardiac rhythm. Differences between cycle lengths in a first heart chamber are determined during an established time interval. Evidence of ectopy associated with irregular coupling intervals is detected from the signal during the established time interval. A rhythm classification output corresponding to a second heart chamber at the expiration of the established time interval is provided in response to the consecutive cycle length differences and the evidence of ectopy associated with irregular coupling intervals.

Abstract: A medical device performs a method for determining a cardiac event by obtaining a signal comprising cardiac cycle length information in a patient and determining cardiac cycle lengths during an established time interval. Noise is detected during the time interval and a cardiac cycle length corresponding to a time of the detected noise is rejected. Cycle length differences are determined from the cycle lengths not rejected during the time interval. The cardiac event is determined in response to the cycle length differences.

Abstract: Techniques are provided for use in a pacemaker or implantable cardioverter/defibrillator (ICD) for distinguishing cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals sensed within a patient, such as hypoglycemia, hyperglycemia or other systemic conditions. In one example, the device detects changes in morphological features of cardiac signals indicative of possible cardiac ischemia within the patient, such as changes in ST segment elevation within an intracardiac electrogram (IEGM). The device determines whether the changes in the morphological features are the result of spatially localized changes within a portion of the heart and then distinguishes cardiac ischemia from other conditions affecting the morphology of electrical cardiac signals based on that determination. In another example, the device exploits the interval between the peak of a T-wave (Tmax) and the end of the T-wave (Tend).

Abstract: An implantable medical device acquires a first cardiac signal in a first heart chamber and a second cardiac signal in a second heart chamber. The device determines if the first signal is unreliable. In response to determining the first signal to be unreliable, the device switches from a first cardiac arrhythmia detection mode of operation to a second cardiac arrhythmia detection mode of operation, the first detection mode requiring the use of both the first cardiac signal and the second cardiac signal and the second detection mode requiring the use of the second cardiac signal and not requiring the use of the first cardiac signal.

Abstract: A system includes 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: A system for cardiac event detection over varying time scales includes implanted electrical leads forming a portion of an implanted cardiotracker and external equipment including external alarm mechanisms and a physicians programmer. The cardiac event detection system monitors the degradation of a patient's cardiovascular condition from one or more causes. A processor computes the electrical signals of a heart signal parameter's average value over a time period for a multiplicity of heart rate ranges. The electrical signals are stored and information transmitted to external equipment.

Abstract: Techniques are provided for detecting stroke within a patient using an implantable medical device in conjunction with an external confirmation system. In one example, a preliminary detection of stroke is performed by a subcutaneous monitor based on an analysis of features of an electrocardiogram (ECG) sensed within the patient. Exemplary ECG features indicative of possible stroke include the onset of prominent U-waves, the onset of notched T-waves, and changes in ST segment duration or QT duration or dynamic trends in these parameters. The monitor transmits a signal indicative of possible stroke to a bedside monitor or other external system, which generates a stroke questionnaire for use in confirming the stroke. Family members or other caregivers input answers to the questionnaire into the external system, which confirms or disconfirms the stroke. Emergency personnel can be automatically notified.

Abstract: Techniques are described for detecting ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. Ischemia is detected based on a shortening of the interval between the QRS complex and the end of a T-wave (QTmax), alone or in combination with a change in ST segment elevation. Alternatively, ischemia is detected based on a change in ST segment elevation combined with minimal change in the interval between the QRS complex and the end of the T-wave (QTend). Hypoglycemia is detected based on a change in ST segment elevation along with a lengthening of either QTmax or QTend. Hyperglycemia is detected based on a change in ST segment elevation along with minimal change in QTmax and in QTend. By exploiting QTmax and QTend in combination with ST segment elevation, changes in ST segment elevation caused by hypo/hyperglycemia can be properly distinguished from changes caused by ischemia.

Abstract: Method for processing cardioelectric signals and corresponding device. The method enables processing previously sampled cardioelectric signals so as to filter the T wave, thereby improving the visualization of the P wave. The method comprises the following stages: [a] dyadic decomposition the signal into bands by calculating its wavelet transform up to a range of frequencies comprised in a first range of 15 to 150 Hz and preferably 20 to 100 Hz, [b] selection of significant bands with P wave [c] processing of the significant bands by modifying the wavelet coefficients using statistical parametric models, and preferably statistical parametric noise suppression models, [d] weighting the non-significant bands by multiplying them by a weighting function, and [e] reconstructing the signal The invention also relates to a device for carrying out this method.

Abstract: Method and apparatus for computer enabled analysis of ECG (electro cardiographic) data by exploiting computerized three-dimensional spatial presentation of the measured data using vectors. A three-dimensional presentation of the human heart may be correlated with waveforms specific for standard ECG or derived ECG signals based on the dipole approximation of the heart electrical activity. Additional tools for analyzing ECG data are also provided which may be used to determine the time of cardiac electrical events, to select specific beats for automated cardiac interval determination, and to flag ECGs that have been evaluated by automated means but may benefit by human reading.

Abstract: An implantable medical device and associated method provide atrial pacing and measure intervals between atrial pacing pulses and subsequently sensed ventricular events. A decreasing trend in the intervals indicative of a pre-junctional rhythm is detected. The atrial pacing pulse is delivered at a shortened atrial pacing pulse interval in response to detecting the decreasing trend to reduce the likelihood of a junctional rhythm.

Abstract: A system for heart performance characterization and abnormality detection includes an interface for receiving signal data representing an electrical signal indicating electrical activity of a patient heart over multiple heart beat cycles. A signal processor uses the received signal data in calculating at least one of, (a) a first signal characteristic value substantially comprising a ratio of a time interval from S wave to T wave, to a time interval from Q wave to S wave and (b) a second signal characteristic value substantially comprising a ratio of a T wave base voltage from a peak of a T wave to a zero base reference voltage, to an R wave base voltage from a peak of an R wave to a zero base reference voltage. A comparator compares at least one of the first and second characteristic values with a threshold value to provide a comparison indicator.

Abstract: Techniques are described for detecting ischemia, hypoglycemia or hyperglycemia based on intracardiac electrogram (IEGM) signals. Ischemia is detected based on a shortening of the interval between the QRS complex and the end of a T-wave (QTmax), alone or in combination with a change in ST segment elevation. Alternatively, ischemia is detected based on a change in ST segment elevation combined with minimal change in the interval between the QRS complex and the end of the T-wave (QTend). Hypoglycemia is detected based on a change in ST segment elevation along with a lengthening of either QTmax or QTend. Hyperglycemia is detected based on a change in ST segment elevation along with minimal change in QTmax and in QTend. By exploiting QTmax and QTend in combination with ST segment elevation, changes in ST segment elevation caused by hypo/hyperglycemia can be properly distinguished from changes caused by ischemia.

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: A method and system for detecting T-wave alternans for use in an implanted medical device uses wave transformation of QT intervals to obtain a reliable measure of TWA. In one embodiment, an array provides alternating sign multiplication factors which are applied respectively to n consecutive QT values. Each successive QT value is high pass filtered and moved sequentially through a queue so that each cycle each of the n QT values is multiplied by one of the factors; the products are summed and made absolute to provide an alternans match value. The alternans match is compared with a noise threshold signal, and alternans is declared when the match exceeds the threshold by a predetermined amount. The array is programmable and can be varied, providing a high degree of flexibility to optimize the test for the patient.

Abstract: A method of determining an ischemic event includes the steps of: monitoring and storing an initial electrocardiogram vector signal (x, y, z) of a known non-ischemic condition over the QRS, ST and T wave intervals; calculating and storing a J-point of the vector signal and a maximum magnitude of a signal level over the T wave interval; monitoring a subsequent electrocardiogram vector signal over the QRS, ST and T wave intervals; measuring and storing the magnitude (Mag.) of the vector difference between a subsequent vector signal and the initial vector signal; measuring and storing the angle (Ang.