Meeting Abstract
Proper contraction of cardiac muscle relies on the coordinated propagation of transmembrane voltage, and disturbances of this propagation can result in deadly cardiac arrhythmias. One such disturbance strongly associated with the onset of fibrillation is a dynamical instability at the cellular level known as alternans, a beat-to-beat alternation in action potential duration (APD). A theoretical model known as the restitution hypothesis describes and predicts alternans via a return map in APD, and decades of work have shown that this model successfully reproduces many experimental observations. Furthermore, the restitution hypothesis likewise predicts a method for suppressing the onset of alternans which has been confirmed by some computational simulations of cardiac cells and tissue; however, few experiments have addressed these predictions due to its difficult implementation. In this talk, I will discuss our development of a closed-loop control scheme to experimentally address the predictions made by the restitution hypothesis via high resolution microelectrode recordings of transmembrane voltages in zebrafish, frog, and rabbit hearts. I will present our results which conclusively show the appearance of alternans in opposition to predictions made by theoretical models and provide an improved model that describes the dynamics.
