Controlling Chaotic Dynamics in Frog Hearts Using Perturbative Pacing

Cardiac tissue exhibits nonlinear voltage dynamics, and at high driving frequencies, it can shift from stable 1:1 activity to irregular or chaotic rhythms. These behaviors occur from instabilities between the pacing interval and the action potential duration, leading to period doubling and higher-order bifurcations. Cardiac arrhythmias, which develop from such unstable dynamics, remain a leading cause of death worldwide, motivating the need for improved pacing strategies. We used ex vivo frog hearts and optical mapping to study how small perturbative pacing can control these dynamics through shifts in the basic cycle length (BCL). We used a pacing protocol that adjusts BCL by fixed amounts to test how small timing perturbations influence the organization of chaos. Results show that initiating perturbative pacing during chaotic activity can modify the local rhythm temporally and spatially across the tissue. We analyzed how this approach guides complex dynamics, including period-doubling, quasiperiodic, and irregular wave behavior. Theoretical modeling using the logistic map and a cardiac map supports these findings, showing how controlled perturbations can restore stable electrical activity. We aim to design an in-the-loop adaptive pacing protocol that updates in real time to suppress arrhythmias. This work advances a nonlinear approach for controlling cardiac dynamics and can lead to new pacemaker technologies for treating heart rhythm disorders.