Frequency and Phase Domains Methods for Mechanisms of Fibrillation

Abstract

Cardiac fibrillation is a leading cause of mortality and morbidity, and despite major research efforts, its mechanisms are still poorly understood. The challenges in understanding the complex patterns of excitation during fibrillation stem mostly from its nonlinear and multifactorial dynamics, but experimental studies utilizing high-resolution optical mapping have demonstrated that in some cases, the complex fibrillation is driven by relatively well-organized reentrant patterns, whose localization was made more accurate by frequency and phase domains processing approaches. The chapter first introduces the concepts of the dominant frequency and the singularity points in the phase space and how they relate to fibrillation and its reentrant activity. It then demonstrates experimental and clinical cardiac mapping cases to illustrate insight gained by those concepts in support of the idea that rotors play a major role in driving fibrillation. Finally, the application of the frequency and phase approaches in noninvasive mapping of atrial and ventricular fibrillation in patients is demonstrated. The processing methods presented in this chapter should enhance any cardiac mapping and possibly improve the understanding of fibrillation and the guidance for its therapy.