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 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 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: Embodiments include cardiac information and activity information association systems, apparatus, and methods. An apparatus embodiment includes a cardiac sensor adapted to generate cardiac information descriptive of cardiac functioning of a patient, an activity sensor adapted to generate activity information indicating physical activity of the patient, a processing element adapted to detect a cardiac anomaly based on the cardiac information, an information association element adapted to generate associated cardiac/activity information during the cardiac anomaly, and a data storage apparatus adapted to store the associated cardiac/activity information.

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 system and method for an implantable cardiac pacing device provide for delivery of anti-tachycardia pacing of the atrium upon detection of atrial tachycardia combined with automatic re-synchronization of ventricular pacing directly following the last atrial pulse of the anti-tachycardia scheme. At the onset of delivery of the ATP train or like scheme of ATP, an appropriate ventricular pacing interval is calculated to enable asynchronous pacing of the ventricle during the ATP and synchronous delivery of the next ventricular pulse at a delay following the end of the ATP train. Upon determination of AT, an algorithm is used to calculate if a ventricular pacing interval can be found that meets maximum and minimum pacing criteria and also provides that the next ventricular pace pulse following the end of the ATP train will follow the last atrial pulse of the train by a suitable AV delay.

Abstract: There is provided a pacemaker system which includes intervention for overdriving the patient's natural heart rate in the event of a sensed incipient ventricular arrhythmia condition, and particularly torsades de pointes. The pacemaker continually acquires QT signals and analyzes them for respective properties, updating statistical information relating to the properties. In a preferred embodiment, the pacemaker analyzes QT interval, QT dispersion, time derivative of the QT interval, and/or T-wave amplitude and determines an intervention for pacing therapy based upon changes to these properties. The pacemaker also monitors premature ventricular beats and generates data representative of such occurrences, which data is used alone or in combination with QT data in determining whether intervention is indicated, for adjusting the intervention pacing rate.

Abstract: There is provided a pacemaker system which includes intervention for overdriving the patient's natural heart rate in the event of a sensed incipient ventricular arrhythmia condition, and particularly torsades de pointes. The pacemaker continually acquires QT signals and analyzes them for respective properties, updating statistical information relating to the properties. In a preferred embodiment, the pacemaker analyzes QT interval, QT dispersion, time derivative of the QT interval, and/or T-wave amplitude and determines an intervention for pacing therapy based upon changes to these properties. The pacemaker also monitors premature ventricular beats and generates data representative of such occurrences, which data is used alone or in combination with QT data in determining whether intervention is indicated, for adjusting the intervention pacing rate.

Abstract: There is provided a cardiac pacing system for dealing with dangerous atrial arrhythmias, wherein when an episode of such an arrhythmia is detected, the system operates to cool the A-V node so as to reversibly block conduction of the atrial excitations through to the ventricle, permitting uninterrupted asynchronous ventricular pacing during the episode. The system provides for an atrial lead having a Peltier element positioned toward its distal end, such that when the atrial lead distal end is affixed to the atrial heart wall, the cooling element is proximate to the A-V node. Upon detection of a dangerous atrial episode, the Peltier element is energized to cool the A-V node to point of effective block, and the pacemaker switches to asynchronous pacing.