Three-dimensional reconstruction of electrical activity in the heart using optical parallax

Until recently, optical mapping of electrical activity in the heart muscle using voltage-sensitive dyes has mainly been applied to subsurface imaging. Here we present a method for the three-dimensional (3D) reconstruction of electrical activity deep inside the myocardial wall. We propose an alternative approach to diffusive optical tomography, based on ideas from binocular vision. Detection and illumination occur on opposite sides of the preparation. Staining with absorptive voltage-sensitive dyes is assumed. Data acquisition follows a paraxial scanning procedure, which modifies coaxial scanning by the introduction of a vector offset between illumination and detection axes. Pairs of 2D images are obtained corresponding to offsets of opposite signs. Those image pairs created by parallax are used as an input for the reconstruction algorithm, whose output is a 3D optical image of intramural electrical excitation. We apply this method to the slab geometry. The procedure was tested for a variety of computer-generated sources including particles, lines, bubbles, and simulated electrophysiological. patterns such as scroll waves. The limitations of the method and possible improvements are discussed.