Discrimination of fast ventricular tachycardia from ventricular fibrillation and slow ventricular tachycardia for an implantable pacer-cardioverter-defibrillator

Implantable Pacer-Cardioverter-Defibrillators (PCD) sense ventricular electrograms from epicardial or endocardial leads with an auto-adjusting threshold and analyze a recent series of cycle lengths with algorithms to detect ventricular tachycardia (VT) and ventricular fibrillation (VF) for tiered therapies. A new algorithm to detect fast ventricular tachycardia (FVT) in a zone between VT and VF either via VT-type counting or via VF-type counting is described. Gaussian strings of cycle lengths with uniformly distributed means and standard deviations and databases of human tachyarrhythmias are analyzed. Detection algorithm sensitivity, specificity with 95% confidence intervals and the predictive value of a positive test for VF (PVP) are studied as a function of programmable defection parameters. While maintaining 100% VF sensitivity, VF specificity is increased by 20% for FVT via VF thereby safely reducing the number of painful shocks