Abstract: Cardiac systems and methods provide for discriminating between supraventricular tachyarrhythmia and ventricular tachyarrhythmia based on a determination that the patient's supraventricular rhythm exhibits rate dependency. One approach involves determining if a patient's supraventricular rhythm exhibits rate dependent morphology. If the patient's supraventricular rhythm is determined to exhibit rate dependent morphology, an implantable device classifies a detected tachyarrhythmia episode based on one or more templates selected from a plurality of rate-indexed templates stored in the device. Determining if the supraventricular rhythm exhibits rate dependent morphology may also include determining one or more rates at which the rate dependent morphology occurs.

Abstract: A system and method for performing off-line analysis of cardiac electrogram data, comprising: retrieving an electrogram from a memory location; identifying a first-channel group of candidate beats from at least a first channel of the electrogram; and identifying a second-channel group of candidate beats from at least a second channel of an electrogram. For each first-channel beat candidate near a second-channel beat candidate, the amplitude of the first-channel beat candidate is compared with the amplitude of a previous beat and the amplitude of a next beat on the first electrogram channel, and first-channel beat candidates that are outside of a first pre-determined range from either the previous or next beat are removed. Then first-channel beat candidates that are outside of a second pre-determined range from either the previous or next beat candidate are removed.

Abstract: A system and method for performing independent, off-line evaluation of event sensing for collected electrograms, comprising: sensing an electrogram using an implantable medical device (IMD); determining locations of heart beats on at least one channel of the electrogram using a multi-pass process, resulting in a group of multi-pass beat locations; storing the electrogram and device-identified beat locations in a memory location; and retrieving the electrogram and device-identified beat locations from the memory location. The multi-pass process determines locations of heart beats on at least a first channel of the electrogram. The device-identified group of beat locations are then compared to the multi-pass group of beat locations identified using the multi-pass method. Based on the comparing step, oversensing of beats, undersensing of beats, or noise from the device can be detected.

Abstract: An indication of an actual or potential heart failure condition is computed. One example includes monitoring a first heart rate preceding a first onset of a first sinus tachyarrhythmia episode. Upon detecting the first sinus tachyarrhythmia episode, the indication is automatically provided using information about the first heart rate and how quickly the first onset occurs.

Abstract: Methods and systems for selecting tachyarrhythmia therapy based on the morphological organization level of the arrhythmia are described. Morphological organization levels of arrhythmias are associated with cardiac therapies. The morphological organization levels are related to cardiac signal morphologies of the arrhythmias. An arrhythmia episode is detected and the morphological organization level of the arrhythmia episode is determined. A cardiac therapy associated with the morphological organization level of the arrhythmia episode is delivered to treat the arrhythmia. For example, the morphological organization levels may be associated with the cardiac therapies based on one or more of retrospective database analysis, patient therapy tolerance, and physician input. The associations may be static or may be dynamically adjusted based on therapy efficacy.

Abstract: Cardiac arrhythmias are classified based on the morphology of the arrhythmia episode beats. Templates are formed using morphological features of the cardiac beats of the episode. The arrhythmia episode is classified as a monomorphic tachyarrhythmia or polymorphic tachyarrhythmia based on the one or more templates. The arrhythmia episode may be classified based on a number templates formed from the arrhythmia episode. The templates are formed by determining a measure of similarity between morphological features of a cardiac beat to a template. The similarities can be determined based on a pairing rule that determines which beat morphologies are compared. Selection of therapy for treating the arrhythmia episode may depend on the historical success of a therapy at mitigating previous arrhythmias of the same type as the arrhythmia episode.

Abstract: A system and method for automatically analyzing a cardiac signal, including the step of providing an episode database on a computer storage medium including a plurality of episode data records of one or more patients. Each episode data record includes a cardiac signal from at least one data-generating device. The method also includes the step of selecting one or more of the N beats to be one or more beat templates, for at least a first cardiac signal having N beats. Another step is determining a value K for the cardiac signal using a computer system where K beat templates can represent all the N beats in the cardiac signal.

Abstract: A system and method for performing off-line analysis of cardiac electrogram data, comprising: retrieving an electrogram from a memory location; identifying a first-channel group of candidate beats from at least a first channel of the electrogram; and identifying a second-channel group of candidate beats from at least a second channel of an electrogram. For each first-channel beat candidate near a second-channel beat candidate, the amplitude of the first-channel beat candidate is compared with the amplitude of a previous beat and the amplitude of a next beat on the first electrogram channel, and first-channel beat candidates that are outside of a first pre-determined range from either the previous or next beat are removed. Then first-channel beat candidates that are outside of a second pre-determined range from either the previous or next beat candidate are removed.

Abstract: A system and method for performing independent, off-line evaluation of event sensing for collected electrograms, comprising: sensing an electrogram using an implantable medical device (IMD); determining locations of heart beats on at least one channel of the electrogram using a multi-pass process, resulting in a group of multi-pass beat locations; storing the electrogram and device-identified beat locations in a memory location; and retrieving the electrogram and device-identified beat locations from the memory location. The multi-pass process determines locations of heart beats on at least a first channel of the electrogram. The device-identified group of beat locations are then compared to the multi-pass group of beat locations identified using the multi-pass method. Based on the comparing step, oversensing of beats, undersensing of beats, or noise from the device can be detected.

Abstract: Detecting or validating signals such as cardiac beats can be performed in the presence of myopotential or other noise. An amplitude peak, which can be a candidate for a detected beat, can be used in a normalized or other weighted average, along with a preceding and subsequent sample. The weighted average is compared to a noise threshold. Based on the result, the amplitude peak is either deemed an actual beat (e.g., depolarization or repolarization), or noise. The described systems, devices, and methods can improve the accuracy of detecting an actual beat in the presence of noise, during normal sinus rhythm or during an arrhythmia such as ventricular fibrillation. This, in turn, improves the accuracy with which therapy is delivered or withheld by an implantable device.

Abstract: Methods and systems for selecting tachyarrhythmia therapy based on the morphological organization level of the arrhythmia are described. Morphological organization levels of arrhythmias are associated with cardiac therapies. The morphological organization levels are related to cardiac signal morphologies of the arrhythmias. An arrhythmia episode is detected and the morphological organization level of the arrhythmia episode is determined. A cardiac therapy associated with the morphological organization level of the arrhythmia episode is delivered to treat the arrhythmia. For example, the morphological organization levels may be associated with the cardiac therapies based on one or more of retrospective database analysis, patient therapy tolerance, and physician input. The associations may be static or may be dynamically adjusted based on therapy efficacy.

Abstract: A method comprises detecting at least one episode of ventricular tachyarrhythmia in a subject using an implantable medical device (IMD), sensing at least one heart sound signal for the subject using the IMD, the heart sound signal associated with mechanical vibration of a heart of the subject; initiating, in response to and during the detected episode of tachyarrhythmia, a measurement of hemodynamic stability of the ventricular tachyarrhythmia from the heart sound signal, and deeming whether the ventricular tachyarrhythmia is stable according to the measurement of hemodynamic stability. The measurement of hemodynamic stability is determined using linear prediction.

Abstract: Cardiac treatment methods and devices provide for templates representative of past tachyarrhythmia events, each template associated with a therapy. Methods involve providing a cardiac waveform representative of a patient's cardiac activity and identifying a portion that indicates an arrhythmic event. A cardiac template corresponding to the portion is generated, and a therapy is associated with the template useful for treating a subsequent arrhythmia. The waveform portion may be identified by a physician using a patient-external device to display the cardiac waveform. The template may be generated by a physician selecting the cardiac waveform, and determining if the therapy associated with the template was satisfactory and/or effective in treating the arrhythmia. Identification may involve matching the event to templates generated using cardiac waveforms other than the patient's cardiac waveforms.

Abstract: A system and method for automatically analyzing a cardiac signal, including the step of providing an episode database on a computer storage medium including a plurality of episode data records of one or more patients. Each episode data record includes a cardiac signal from at least one data-generating device. The method also includes the step of selecting one or more of the N beats to be one or more beat templates, for at least a first cardiac signal having N beats. Another step is determining a value K for the cardiac signal using a computer system where K beat templates can represent all the N beats in the cardiac signal.

Abstract: Methods and systems for selecting tachyarrhythmia therapy based on the morphological organization level of the arrhythmia are described. Morphological organization levels of arrhythmias are associated with cardiac therapies. The morphological organization levels are related to cardiac signal morphologies of the arrhythmias. An arrhythmia episode is detected and the morphological organization level of the arrhythmia episode is determined. A cardiac therapy associated with the morphological organization level of the arrhythmia episode is delivered to treat the arrhythmia. For example, the morphological organization levels may be associated with the cardiac therapies based on one or more of retrospective database analysis, patient therapy tolerance, and physician input. The associations may be static or may be dynamically adjusted based on therapy efficacy.

Abstract: A method comprises detecting at least one episode of ventricular tachyarrhythmia in a subject using an implantable medical device (IMD), sensing at least one heart sound signal for the subject using the IMD, the heart sound signal associated with mechanical vibration of a heart of the subject; initiating, in response to and during the detected episode of tachyarrhythmia, a measurement of hemodynamic stability of the ventricular tachyarrhythmia from the heart sound signal, and deeming whether the ventricular tachyarrhythmia is stable according to the measurement of hemodynamic stability. The measurement of hemodynamic stability is determined using linear prediction.

Abstract: A system comprising an implantable medical device (IMD). The IMD includes an implantable sensor operable to produce an electrical signal representative of mechanical activity of a heart of a subject and a controller circuit coupled to the sensor. The IMD also includes a heart sound sensor interface circuit to produce a heart sound signal, a tachyarrhythmia detector, and a controller circuit. The controller circuit includes a hemodynamic stability assessment module configured to determine that at least one episode of ventricular tachyarrhythmia is detected in a subject and obtain a measurement of hemodynamic stability of the ventricular tachyarrhythmia from the heart sound signal.

Abstract: Cardiac systems and methods provide for discriminating between supraventricular tachyarrhythmia and ventricular tachyarrhythmia based on a determination that the patient's supraventricular rhythm exhibits rate dependency. One approach involves determining if a patient's supraventricular rhythm exhibits rate dependent morphology. If the patient's supraventricular rhythm is determined to exhibit rate dependent morphology, an implantable device classifies a detected tachyarrhythmia episode based on one or more templates selected from a plurality of rate-indexed templates stored in the device. Determining if the supraventricular rhythm exhibits rate dependent morphology may also include determining one or more rates at which the rate dependent morphology occurs.

Abstract: Cardiac systems and methods provide for discriminating between supraventricular tachyarrhythmia and ventricular tachyarrhythmia based on a determination that the patient's supraventricular rhythm exhibits rate dependency. One approach involves determining if a patient's supraventricular rhythm exhibits rate dependent morphology. If the patient's supraventricular rhythm is determined to exhibit rate dependent morphology, an implantable device classifies a detected tachyarrhythmia episode based on one or more templates selected from a plurality of rate-indexed templates stored in the device. Determining if the supraventricular rhythm exhibits rate dependent morphology may also include determining one or more rates at which the rate dependent morphology occurs.

Abstract: An indication of an actual or potential heart failure condition is computed. One example includes monitoring a first heart rate preceding a first onset of a first sinus tachyarrhythmia episode. Upon detecting the first sinus tachyarrhythmia episode, the indication is automatically provided using information about the first heart rate and how quickly the first onset occurs.