Distinction of arrhythmias with the use of approximate entropy

Specialized therapies in the implantable cardioverter defibrillator (ICD) of antitachycardia pacing, low-energy cardioversion, and defibrillation can be used to treat ventricular tachycardia (VT) and ventricular fibrillation (VF) in a directed tiered approach. As devices improve, more advanced signal processing algorithms have been suggested to further refine the direction of therapy by first attempting lower energy therapies for VT, in order to minimize patient discomfort and battery depletion. The aim of this study is to further evaluate a complexity or regularity measure called approximate entropy for its ability to distinguish between morphologic regularity in VT and VF. High approximate entropy indicates irregularity, while low values indicate regularity. This measure has previously been used for heart rate variability quantification