[Time, space and frequency in ventricular fibrillation].

Ventricular fibrillation (VF) is the main immediate cause of sudden, unexpected cardiac death. It appears in the electrocardiogram (ECG) as an aperiodic, irregular rhythm, giving the impression that electrical activation of the ventricles is highly complex and disordered. Unfortunately, despite many years of research and speculation, it has still not been possible to confirm or reject that idea, and therefore, the mechanism underlying VF continues to be a highly debated subject. During the second half of the 20th century, the predominant hypothesis to explain both VF and atrial fibrillation (AF) was based on multiple wavefronts that propagated in a random and disorganized manner.1 In 1994, Authur T. Winfree2 introduced in the Western literature a new alternative theory involving “threedimensional electrical rotors” that would become unstable when the thickness of the ventricular wall exceeded a critical value. Winfree believed that in some cases various rotors could be “anchored” in the ventricles to collectively maintain activity similar to fibrillation, even when recording electrodes revealed apparently periodic electrical activity. That hypothesis was consistent with experimental findings showing that the heart could sustain reentrant activity around a functional obstacle,3 and led to the suggestion that rotors could be the organizing centers for VF. Since then, a large number of studies have addressed the involvement of rotors and spiral waves, either stable or unstable, in VF.4-6 This has led to the development of new analytic techniques that allow quantification of Time, Space, and Frequency in Ventricular Fibrillation