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

Action potential waves triggering the heart's contractions can be imaged at high spatial and temporal resolutions across the heart surface using voltage-sensitive optical mapping. However, for over three decades, optical mapping has been performed with contraction-inhibited hearts. While it was recently demonstrated that action potential waves can be imaged on parts of the three-dimensional deforming ventricular surface using multi-camera optical mapping, panoramic measurements of action potential waves across the entire beating heart surface remained elusive. Here, we introduce a high-resolution multi-camera optical mapping system consisting of up to 24 high-speed, low-cost cameras with which it is possible to image action potential waves at high resolutions on the entire, strongly deforming ventricular surface of the heart. We imaged isolated hearts inside a custom-designed soccerball-shaped imaging chamber, which facilitates imaging and even illumination with excitation light from all sides in a panoramic fashion. We found that it is possible to image the entire ventricular surface using 12 cameras with 0.5-1.0 megapixels combined resolution. The 12 calibrated cameras generate 1.5 gigabytes of video data per second at imaging speeds of 500 fps, which we process using various computer vision techniques, including three-dimensional cooperative multi-view motion tracking, to generate three-dimensional dynamic reconstructions of the deforming heart surface with corresponding high-resolution voltage-sensitive optical measurements. With our setup, we measured action potential waves at unprecedented resolutions on the contracting three-dimensional surface of rabbit hearts during sinus rhythm, paced rhythm as well as 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 dynamics during health and disease.