Abstract: A method, apparatus, and computer program product for predicting ventricular tachyarrhythmia (VTA) are disclosed. To provide a mechanism that allows prediction of VTA events efficiently within a few hours before the onset of the actual event, a set of repolarization parameters indicative of ventricular repolarization in a subject's heart is determined in successive time segments, thereby to obtain a time series of the set of repolarization parameters. Based on the time series, at least one change indication variable indicative of changes in the ventricular repolarization of the heart is produced and the risk of potential ventricular tachyarrhythmia is predicted based on the at least one change indication variable. (FIG. 1).

Abstract: An apparatus comprises a cardiac signal sensing circuit, a physiologic sensor circuit configured to provide a physiologic sensor signal representative of mechanical cardiac activity, a therapy circuit, and a control circuit. The control circuit includes a cardiac depolarization detection circuit, a tachyarrhythmia detection circuit, and a timer circuit. A time interval between a mechanical cardiac event and a detected fiducial electrical cardiac event is monitored. The control circuit is configured to correct the monitored time interval for variation with heart rate to form a corrected electromechanical time interval, initiate anti-tachyarrhythmia therapy when the corrected electromechanical time interval satisfies a specified time interval threshold value during a detected episode of tachyarrhythmia, and withhold anti-tachyarrhythmia therapy otherwise.

Abstract: A method, system, and device for detection of an arrhythmia, and discrimination between different types of arrhythmia, for example to determine whether to administer an electric shock to the heart, the device comprising a wearable monitor with electrodes that detect the electrical activity of a beating heart, attached to an embedded monitoring system having an amplifier, a microprocessor, a data storage device, and a power supply, all disposed on a substrate having large distal end portions that attach to the electrodes and a narrow intermediate portion that attaches to the monitoring system.

Abstract: Methods for performing cardiac signal analysis in an implanted medical device, and devices configured to perform illustrative methods of cardiac signal analysis. A cardiac signal is captured by an implanted device using implanted electrodes and, during at least certain conditions, the cardiac signal undergoes heuristic filtering. In some embodiments, heuristic filtering is achieved by modifying a signal or value that is used as an indicator of received signal amplitude. In an illustrative example, the heuristic filtering includes periodically incrementing or decrementing the signal or value toward a desired quiescent point, where the heuristic filter period is significantly longer than the sampling period for the signal itself. In another illustrative example, the heuristic filter frequency can be adjusted dynamically to keep the signal average near the desired quiescent point.

Abstract: A TWA measuring apparatus includes: a T-wave feature quantity measuring section; a classifying section classifying T-wave feature quantities into groups of odd and even electrocardiogram waveforms; a reliability index calculating section calculating: first and second representative values and first and second dispersion values of the T-wave feature quantities in the odd and even group; a difference between the first and second representative values, to obtain a TWA feature quantity; and an adjustment value between the first representative value and the first dispersion value, and an adjustment value between the second representative value and the second dispersion value, to obtain a reliability index; and a reliability recognizing section recognizing: when the reliability index exceeds a threshold, that reliability of the TWA feature quantity is high; and when the reliability index does not exceed the threshold, that the reliability is low.

Abstract: In an implantable medical device such as an implantable cardiac defibrillator, and a method for classifying arrhythmia events, IEGM signals are analyzed to detect an arrhythmia event and a respiratory pattern of the patient is sensed. At least one respiratory parameter reflecting characteristics of the respiratory pattern of the patient is determined based on the sensed respiratory pattern and a respiratory measure corresponding to a change of a rate of change of the at least one respiratory parameter is calculated. The detected arrhythmia event is classified based on the respiratory measure and the IEGM signals, wherein arrhythmia events that satisfy at least a first criterion is classified as an arrhythmia event requiring therapy.

Abstract: A mobile system for analyzing ECG data includes an analog front end module coupled to a mobile consumer device. The analog front end module is configured to collect ECG data from one or more leads and is operable to convert the analog ECG data to digital ECG data. The mobile consumer device is coupled to receive the digital ECG data, and is configured to perform QRS detection using a filter whose cutoff frequency is adapted to noise level in real time. The ECG signal is amplified non-linearly and three windowed threshold signals (D, E, J) are derived. The cutoff frequency for the QRS detection is dynamically selected as a function of the threshold signals. A sample in the amplified signal is identified to be a heart beat point only when the sample value is equal to the first threshold signal and greater than the filtered threshold signal.

Abstract: Measured values of ST segment deviations obtained from a multi-lead ECG are transformed and displayed on a polar ST Circle Display, with zero ST deviation values located on a circle having a diameter that is greater than a maximum absolute ST segment deviation value obtained for any measured or derived lead. An ischemic condition and a location of the ischemia can thereby be easily determined.

Abstract: An implantable heart stimulating device for indicating congestive heart failure (CHF) has a processor and a sensor combination that senses at least two heart events during one heart cycle at different locations of the heart. The processor is supplied with signals from the sensor combination relating to the sensed events, and determines therefrom at least one heart time interval between the sensed events in the same heart cycle. The processor determines a CHF indicator value representing a degree of CHF based on a variability measure calculated from at least two heart time intervals from at least two different heart cycles. The processor determines the CHF indicator value in relation to previous CHF indicator values.

Abstract: The present invention provides an improved, Internet-based system that seamlessly collects cardiovascular data from a patient before, during, and after a procedure for EP or an ID. During an EP procedure, the system collects information describing the patient's response to PES and the ablation process, ECG waveforms and their various features, HR and other vital signs, HR variability, cardiac arrhythmias, patient demographics, and patient outcomes. Once these data are collected, the system stores them on an Internet-accessible computer system that can deploy a collection of user-selected and custom-developed algorithms. Before and after the procedure, the system also integrates with body-worn and/or programmers that interrogate implanted devices to collect similar data while the patient is either ambulatory, or in a clinic associated with the hospital. A data-collection/storage module, featuring database interface, stores physiological and procedural information measured from the patient.

Abstract: A device for detecting cardiac ischemia is disclosed. The device includes a processor that is configured to distinguish between two different heart beats types such as left bundle branch block beats and normal sinus beats. The processor applies different ischemia tests to the two different beat types, and generates alert when it detects ischemia.

Abstract: An example system and method of processing cardiac activation information are disclosed. The method includes accessing a first cardiac signal and a second cardiac signal obtained from a patient. The first cardiac signal and the second cardiac signal are processed to identify a point of change in the first cardiac signal at which a derivative of the first cardiac signal diverges with respect to a derivative of the second cardiac signal. An activation onset time is assigned in the first cardiac signal at the point of change to define a cardiac activation.

Abstract: A system for the detection of cardiac events occurring in a human patient is provided. At least two electrodes are included in the system for obtaining an electrical signal from a patient's heart. An electrical signal processor is electrically coupled to the electrodes for processing the electrical signal and a patient alarm means is further provided and electrically coupled to the electrical signal processor. The electrical signal is acquired in the form of electrogram segments, which are categorized according to heart rate, ST segment shift and type heart rhythm (normal or abnormal). Baseline electrogram segments are tracked over time.

Abstract: An implantable medical device and associated method for classifying a patient's risk for arrhythmias by sensing a cardiac electrogram (EGM) signal and selecting a first pair of T-wave signals and a second pair of T-wave signals. A first difference between the two T-wave signals of the first pair is compared to a second difference between the two T-wave signals of the second pair. A T-wave alternans phase reversal is detected in response to comparing the first difference and the second difference, and the patient's arrhythmia risk is classified in response to detecting the phase reversal.

Abstract: Physiologic demand driven pacing can be used to maintain cardiac synchrony and improve hemodynamic function in patients with heart failure.

Abstract: A two-dimensional refractory period is defined in conjunction with the detection of cardiac events. Detection parameters associated with the two-dimensional refractory period may define a period of time during which a sensed cardiac signal is blanked or may define a period of time during which a given sensing threshold applies. The two-dimensional refractory period may be employed in atrial sensing to selectively blank far-field T-waves while enabling P-wave detection. The two-dimensional refractory period may be employed in ventricular sensing to selectively blank near-field T-waves while enabling detection of the QRS complex. The detection parameters associated with the two-dimensional refractory period may be adapted based on characteristics of previously detected cardiac signals.

Abstract: While analyzing ventricular repolarization in accordance with the invention, ECG measurement with excitation of heart rate is evaluated and the coupling of an internal parameter, for example QT to heartbeat interval, for example RR, is modeled by a transfer function with three parameters. The values of the resulting five parameters describing the static and dynamic characteristics of ventricular repolarization are obtained by means of transfer function parameters and the measured values of heart rate and the internal parameter. The effect of medication is evaluated from the difference of the values of these parameters determined before and after administrating the medication.

Abstract: A method includes retrieving electrogram (EGM) data for N cardiac cycles from a memory of an implantable medical device. N is an integer greater than 1. The method further include categorizing each of the N cardiac cycles into one of a plurality of categories based on a morphology of the N cardiac cycles and performing comparisons between pairs of the N cardiac cycles. Each of the comparisons between two cardiac cycles includes detecting a mismatch between the two cardiac cycles when the two cardiac cycles are in different categories, and detecting a match between the two cardiac cycles when the two cardiac cycles are in the same category. Additionally, the method includes classifying the rhythm of the N cardiac cycles based on a number of detected matches and detected mismatches.

Abstract: Techniques include determining a first vector of temporal changes in electrical data measured at multiple electrical sensors positioned at corresponding locations on a surface of a living body due to a natural electrical pulse. A different vector of temporal changes in electrical data measured at the same electrical sensors is determined due to each stimulated signal of multiple stimulated signals within the living body. Stimulated position data is received, which indicates a different corresponding position within the living body where each of the stimulated signals originates. The site of origin of the natural electrical pulse is determined based on the first vector and the multiple different vectors and the stimulated position data. Among other applications, these techniques allow the rapid, automatic determination of the site of origin of ventricular tachycardia arrhythmia (VT).

Abstract: Measured values of ST segment deviations obtained from a multi-lead ECG are transformed and displayed on a polar ST Circle Display, with zero ST deviation values located on a circle having a diameter that is greater than a maximum absolute ST segment deviation value obtained for any measured or derived lead. An ischemic condition and a location of the ischemia can thereby be easily determined.

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: Methods for determination of timing for electrical shocks to the heart to determine shock strength necessary to defibrillate a fibrillating heart. The timing corresponds the window of most vulnerability in the heart, which occurs during the T-wave of a heartbeat. Using a derivatized T-wave representation, the timing of most vulnerability is determined by a center of the area method, peak amplitude method, width method, or other similar methods. Devices are similarly disclosed embodying the methods of the present disclosure.

Abstract: A system for heart performance characterization uses an interface to receive waveform signal data representing electrical activity of a patient heart over at least one heart beat cycle. The signal processor uses a signal peak and amplitude detector for, identifying a first signal portion of a first heart cycle of the signal data, identifying multiple different amplitude levels within the first signal portion, determining a first area under the waveform in the first signal portion corresponding to at least one particular amplitude level and deriving a parameter in response to the determined first area. The output processor generates an alert message if at least one of, (a) the derived parameter and (b) a difference between the derived parameter and a corresponding derived parameter for a different heart cycle for the same patient, exceeds a predetermined threshold value.

Abstract: A device and method of detecting the severity of myocardial ischemia and heart attack risk is provided. The method includes obtaining an electrogram signal, determining T-wave measurements based on the electrogram signal, and determining ST segment measurements based on the electrogram signal. The method also includes identifying T-wave alternans based on the T-wave measurements and identifying ST segment changes based on the ST segment measurements. The method further includes correlating the T-wave alternans with the ST segment changes in order to detect a severity of ischemia.

Abstract: A TWA measuring apparatus includes: a grouping section which is configured to group electrocardiogram waveforms of a subject in increments of a first beat number, to generate a plurality of first groups; a storage section which is configured to store the electrocardiogram waveforms; a testing section which is configured to test a statistical intergroup difference of measurement values of the electrocardiogram waveforms of the first groups; a heartbeat condition determining section which is configured to determine that a heartbeat condition is unstable, when a significant statistical difference exists between the first groups; and a TWA measuring section which is configured to measure variation in heartbeat by using the stored electrocardiogram waveforms, when it is determined that the heartbeat condition is unstable.

Abstract: A method, apparatus, and computer program product for predicting ventricular tachyarrhythmia (VTA) are disclosed. To provide a mechanism that allows prediction of VTA events efficiently within a few hours before the onset of the actual event, a set of repolarization parameters indicative of ventricular repolarization in a subject's heart is determined in successive time segments, thereby to obtain a time series of the set of repolarization parameters. Based on the time series, at least one change indication variable indicative of changes in the ventricular repolarization of the heart is produced and the risk of potential ventricular tachyarrhythmia is predicted based on the at least one change indication variable.

Abstract: Disclosed embodiments include a method for assessing fluid responsiveness implemented in a medical apparatus, a medical system, or a digital computer with one or more processors comprising: (a) measuring an electrocardiogram signal, and (b) computing a dynamic index predictive of fluid responsiveness from said electrocardiogram by calculating the R-wave amplitude variability over one or more respiratory cycles. According to one particular embodiment, the ECG changes in R-wave amplitude are calculated from the DII lead to generate a dynamic index to guide fluid therapy.

Abstract: A method includes storing an electrogram (EGM) template in a memory. The EGM template includes first and second alignment points at first and second peaks of the EGM template, respectively. The method further includes identifying first and second peaks of a cardiac cycle EGM acquired by a medical device and selecting one of the first and second peaks of the cardiac cycle EGM to align with one of the first and second alignment points based on an order in which the first and second peaks of the cardiac cycle EGM occur. Additionally, the method includes aligning the selected one of the first and second peaks with one of the first and second alignment points and determining an amount of similarity between the cardiac cycle EGM and the EGM template after alignment.

Abstract: A method of measuring the instantaneous period of a quasi-periodic signal includes determining an initial template, performing a cross-correlation between the initial template and a quasi-periodic signal and selecting portions of the signal that correspond to the peaks of the correlation signal. The selected portions are then averaged and another cross correlation is performed between the quasi-periodic signal and a template including the averaged selected portions. The instantaneous period is then measured from the correlation signal.

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: 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 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 heart rate dependent acute ischemia detection thresholds. If the statistical distribution associated with a heart rate range is insufficient, the threshold for that heart rate range is set as a function of the threshold for a neighboring heart rate range. Thresholds are also increased for heart rate ranges associated with statistical distributions that are sufficient but that have a relatively small number of entries.

Abstract: A method of assessing contractility of a cardiac muscle which has at least one activation parameter, the method comprising: (a) utilizing time correlated data pertaining to at least one activation parameter to produce a profile of said parameter; (b) identifying from measurement of said at least one parameter a time interval during which interference from an artificial signal occurs; (c) ameliorating effects of said interference; and (d) analyzing changes in said profile to generate an indication of contractility, as a function of time to generate a cardiac activation profile.

Abstract: A computer-implemented method for analyzing a physiological signal includes selecting a first time interval containing a pattern of interest in a recording of the physiological signal. Respective values of a characteristic of the physiological signal are computed in a plurality of time segments within the first time interval. The computed values are concatenated to form a signature of the pattern of interest. A further occurrence of the pattern of interest is identified in the physiological signal during a second time interval by matching the signal in the second time interval to the signature.

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: 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: Methods for performing cardiac signal analysis in an implanted medical device, and devices configured to perform illustrative methods of cardiac signal analysis. A cardiac signal is captured by an implanted device using implanted electrodes and, during at least certain conditions, the cardiac signal undergoes heuristic filtering. In some embodiments, heuristic filtering is achieved by modifying a signal or value that is used as an indicator of received signal amplitude. In an illustrative example, the heuristic filtering includes periodically incrementing or decrementing the signal or value toward a desired quiescent point, where the heuristic filter period is significantly longer than the sampling period for the signal itself. In another illustrative example, the heuristic filter frequency can be adjusted dynamically to keep the signal average near the desired quiescent point.

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: 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 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: 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: A method for delineation of characteristic points in an electrocardiogram signal includes the steps of: (a) processing the electrocardiogram signal to obtain at least one multiscale differential operator wavelet transform thereof; and (b) locating at least one characteristic point in at least one wave segment of the electrocardiogram signal based on the at least one multiscale differential operator wavelet transform.

Abstract: An implantable medical device in which an electrogram is recorded and analyzed in order to detect changes indicative of cardiac ischemia. Cardiac ischemia may be detected by recording an electrogram from a sensing channel of the device and comparing the recorded electrogram with a reference electrogram. If cardiac ischemia is detected, a cardiac drug such as a thrombolytic agent is delivered.

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: 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: Disclosed is a system for the detection of cardiac events that includes an implanted device called a cardiosaver, a physician's programmer and an external alarm system. The system is designed to provide early detection of cardiac events such as acute myocardial infarction or exercise induced myocardial ischemia caused by an increased heart rate or exertion. The system can also alert the patient with a less urgent alarm if a heart arrhythmia is detected. Using different algorithms, the cardiosaver can detect a change in the patient's electrogram that is indicative of a cardiac event within five minutes after it occurs and then automatically warn the patient that the event is occurring. To provide this warning, the system includes an internal alarm sub-system (internal alarm means) within the cardiosaver and/or an external alarm system (external alarm means) which are activated after the ST segment of the electrogram exceeds a preset threshold.

Abstract: Post-exercise arrhythmias are detected by an implantable medical device. In some aspects, post-exercise arrhythmia may be prognostic of a worsening cardiovascular condition. Thus, the detection of post-exercise arrhythmia may be used as an indicator for adjusting the therapy prescribed for a patient. In some aspects post-exercise arrhythmia are detected if a patient is exercising at a level that equals or exceeds a threshold exercise level. In some aspects, therapy for a patient is modified if the detected post-exercise arrhythmia exceeds a threshold arrhythmia level. In some aspects therapy for a patient is modified if ischemia is detected in conjunction with post-exercise arrhythmia.