Evaluation of techniques for recognition of ventricular arrhythmias by implanted devices.
Implantable devices that provide antitachycardia and defibrillation capability currently have limited ability to distinguish among different cardiac rhythms. We have investigated three methods of electrogram analysis: rate, irregularity, and amplitude distribution. In 35 episodes in 19 patients, we applied these three algorithms to 15 s recorded passages of ventricular electrograms during supraventricular tachycardia (N = 11), ventricular tachycardia (N = 11), and ventricular fibrillation (N = 13). Each was individually paired with a recording of sinus rhythm from the same patient. All recordings were obtained during standard electrophysiologic testing. Each algorithm was successful at distinguishing the tachyarrhythmias from sinus rhythm at one or more levels of algorithm parameterization. Rate alone discriminated supraventricular tachycardia from ventricular fibrillation but did not distinguish between supraventricular and ventricular tachycardia. Rate combined with irregularity distinguished between ventricular tachycardia and ventricular fibrillation, but did not discriminate between ventricular and supraventricular tachycardia. Although the amplitude distribution algorithm was unable to separate perfectly any of the three tachyarrhythmias, it provided the best performance in separating supraventricular and ventricular tachycardia (82 percent sensitivity and specificity). We conclude that algorithms based on rate, irregularity, and amplitude distribution analysis of ventricular electrograms may distinguish sinus rhythm from tachyarrhythmias, but may not distinguish among tachyarrhythmias.