Abstract: Recognizing that delivery of pacing therapy to a patient may increase the risk of inappropriate delivery of anti-tachyarrhythmia therapy, a modified atrial-based timing device and method delivers pacing and anti-tachyarrhythmia therapy to the patient such that the risk is reduced. A ventricular-atrial (VA) time interval is increased, when an intrinsic ventricular activation is sensed during an atrial-ventricular (AV) time interval, by the time remaining in the immediately preceding AV time interval following the intrinsic ventricular activation sensed therein. As a result, the patient's heart rate is not elevated, in response to ventricular activations sensed during the AV time interval, and a tachyarrhythmia rate threshold is not exceeded, thereby avoiding inappropriate delivery of anti-tachyarrhythmia therapy.

Abstract: An implantable antiarrhythmia device which detects and classifies arrhythmias of the human heart, and delivers appropriate therapy. The device employs a method of arrhythmia classification based on a set of prioritized rules, each of the rules defining a plurality of criteria based upon characteristics of sensed depolarizations of heart tissue, each rule being met when the criteria associated with the rule are met. Some rules, when met, trigger delivery of antiarrhythmia therapy. Other rules, when met, inhibit delivery of antiarrhythmia therapy. The rules may be met simultaneously, and if so, the highest priority rule governs the behavior of the device.

Abstract: A method and system for determining Acute Myocardial Infarction. The method and system work by determining whether or not at least one pre-specified component wave is present within each successive heartbeat waveform (e.g. the S wave component of the QRSTU waveform) appearing within each electrocardiographic lead. After it has been determined whether or not the pre-specified component wave is present within the heartbeat waveforms under consideration (each lead will generally have some representation of each successive heartbeat waveform present within it), a wave amplitude ratio (e.g. the ST complex amplitude divided by the S wave component amplitude at some specified instant in time) is calculated. Thus, for each successive heartbeat waveform there will generally be at least one wave amplitude ratio calculated for each electrocardiographic lead, since the same heartbeat waveform generally appears, in some form, within each electrocardiographic lead.