Qualitative chaos analysis for ventricular tachycardia and fibrillation based on symbolic complexity

Ventricular fibrillation (VF) is one of the most serious malignant arrhythmias, usually resulting from immediate degeneration of ventricular tachycardia (VT). The surrogate data test (SDT) has been employed in the qualitative detection and analysis of cardiac chaos. Unfortunately, the current SDT method, based on the GP (Grassberger and Procaccia) algorithm, may not be suitable for the analysis of VF rhythm, which has been shown to be a high-dimensional signal. This paper proposes a novel qualitative analysis method based on symbolic dynamics for chaotic systems: the complexity dispersity method. Compared with the GP algorithm, our qualitative complexity method demonstrates better analytical accuracy and robustness and requires less data points (5 seconds vs 20 seconds). When used in the analysis of experimental data, our method achieved 100% accuracy in the detection of cardiac pathology for VT and VF.