Two-pulse Spiral Wave Initiation in Live Cardiac Tissue Using a Microcontroller

In cardiac tissue, propagating action potential (AP) wavefronts trigger muscle contraction and coordinate the uniform pumping of the heart. Instabilities in the wavefront can cause the AP to break and spiral, reentering the tissue and causing uncoordinated contraction that can lead to sudden cardiac death. In investigations of breakdown dynamics and spiral wave (SW) evolution, programmed electrical stimuli (PES) are used to intentionally break the symmetry of AP fronts. We implement the two-pulse S1S2 PES, which uses a primary stimulus under normal pacing conditions to generate a uniform wavefront, producing a heterogeneously excitable space of repolarizing tissue. A second pulse in this region can generate a SW. We present optical mapping measurements of the transmembrane potential in frog and porcine tissue to characterize the induction of SW with a microcontroller. We observed effective initiation within a range of interpulse periods (∆t_s) in both porcine (380-420ms) and frog (220-320ms) hearts. In this talk I will show sample movies from SW initiation and demonstrate the economic use of an Arduino for tissue stimulation in ex-vivo models.