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 such as fibrillation, the manifestation of chaos in the heart. Even in healthy tissue, high heart rates can drive the system to a dynamical instability known as alternans, a period doubling bifurcation in action potential duration (APD) which is strongly correlated with the onset of fibrillation and sudden cardiac death. A functional relationship between the APD and preceding diastolic interval (DI) known as the restitution hypothesis aims to predict the onset of alternans. Much theoretical effort based on the restitution hypothesis has aimed to suppress the onset of alternans through cardiac stimulation at a constant DI with very positive results; however, few experiments have addressed these predictions. In this talk, I will discuss comparative cardiac dynamics in the hearts of species including rabbit, dog, cat, pig, frog, zebrafish, snake, lizard, and alligator through the use of microelectrode recordings and high spatiotemporal resolution optical mapping of fluorescent voltage and calcium signals across the surfaces of hearts. Furthermore, I will discuss my closed-loop control system for performing constant DI stimulation and the highly unexpected results.
