Dynamics and Molecular Mechanisms of Ventricular Fibrillation in Normal Hearts

Humans have known for thousands of years that cardiac fibrillation may lead to death. However, seminal contributions to the elucidation of the mechanisms of fibrillation both in the atria and ventricles began less than 200 years ago with the discovery of bioelectricity. Throughout the 20th century, many investigators contributed to our current, yet incomplete, understanding of the mechanisms of such complex arrhythmias at the organ and cellular levels. At the dawn of the 21st century, the advent of molecular biology approaches in the study of the structure, function, and regulation of membrane ion channels, together with our ability to visualize the dynamics of cardiac wave propagation in two and three dimensions, has opened a new window of opportunity for the discovery of the precise manner in which the molecular structure of the cardiac muscle allows the conditions for initiation and maintenance of fibrillation in both atria and ventricles. In this chapter, I focus on the mechanisms of maintenance of ventricular fibrillation (VF). Specifically, I review some potentially exciting results on the possible role played by inward rectifier channels in the mechanism of VF. As I see it, this new knowledge may be an initial step toward a detailed understanding of the molecular basis of VF and hopefully to the development of new approaches aimed to prevent VF in patients at risk.