Oral: Characterizing Cardiac Dynamics of Zebrafish

Ventricular fibrillations (VF) are deadly irregular rhythms in the heart, as they can lead to sudden cardiac death. Alternans is a period doubling bifurcation where the action potential duration alternates between long and short durations, and has proven to be a strong predictor of VF and cardiac arrest. A variety of physiological factors can influence alternans and eventually cause fibrillations. A common animal model for studying cardiac electrophysiology is zebrafish models, as they closely reproduce the human cardiac action potential and some pathologies. However, there is no current characterization of alternans in Zebra fish hearts or any fish in general.

We present results from Zebra fish hears superfused in Tyrode solution and electrically stimulated in a large range of periods and the action potentials are measured using optical mapping and a voltage sensitive dye to create a restitution curve. This indicates adaptation of the heart to different periods of stimulation and can display the transition to alternans. We show that Alternans is present when the slope of this curve is greater than one in accordance with a mathematical model prediction, which it fish happens in between 200-250ms and can have large duration differences of up to 100ms.