Panoramic Voltage-Sensitive Optical Mapping of Contracting Hearts using Cooperative Multi-View Motion Tracking with 12 to 24 Cameras.

Voltage-sensitive fluorescence imaging is widely used to image action potential waves in the heart. However, while the electrical waves trigger mechanical contraction, imaging needs to be performed with pharmacologically contraction-inhibited hearts, limiting studies of the coupling between cardiac electrophysiology and tissue mechanics. Here, we introduce a high-resolution multi-camera optical mapping system with which we image action potential waves at high resolutions across the entire ventricular surface of the beating and strongly deforming heart. We imaged intact isolated rabbit hearts inside a soccer-ball shaped imaging chamber facilitating even illumination and panoramic imaging. Using 12 high-speed cameras, ratiometric voltage-sensitive imaging, and three-dimensional (3D) multi-view motion tracking, we reconstructed the entire 3D deforming ventricular surface and performed corresponding voltage-sensitive measurements during sinus rhythm, paced rhythm, and ventricular fibrillation. Our imaging setup defines a new state-of-the-art in the field and can be used to study the heart's electromechanical physiology during health and disease at unprecedented resolutions. For instance, we measured electrical activation times and observed mechanical strain waves following electrical activation fronts during pacing, observed electromechanical vortices during ventricular fibrillation, and measured action potential duration and contractile changes in response to pharmacological blockage of potassium ion channels.