Nonlinear Dynamics of Cardiac Arrhythmias

Alain Karma

Department of Physics, Northeastern University

Transitions from order to chaos have been widely studied by physicists in the context of fluid turbulence and other dynamical systems. Recently, physicists have teamed up with biologists and clinicians to help tame cardiac fibrillation, a form of wave turbulence that stops the heart from pumping blood and is the leading cause of sudden death among industrialized nations. Medical doctors routinely defibrillate patients on the show ER and in real life. Some high risk patients can carry implantable defibrillators. However, reducing mortality in the wider population of patients who die suddenly and unpredictably from ventricular fibrillation has remained a major challenge. At the heart of this challenge is a quest for a fundamental understanding of electrical waves that propagate contraction through the main chambers of the heart. These highly nonlinear waves behave quite differently from the linear waves that propagate sound or light. Plane waves annihilate when they and can break up into rapidly rotating spiral-shaped waves that are widely believed to cause fibrillation. Furthermore, wave propagation is governed by an electrical circuitry of bewieldering complexity at molecular, cellular, and tissue scales. In this lecture, I will review the rich scientific history that has lead to modern conceptualizations of fibrillation. I will also discuss recent insights into wave dynamics from a physics perspective that offers new prospects to tame cardiac fibrillation and goes beyond the limitations of current therapies.