Three-dimensional surface reconstruction and fluorescent visualization of cardiac activation

Optical imaging of transmembrane potentials in cardiac tissue is a rapidly growing technique in cardiac electrophysiology. Traditional studies typically use a monocular imaging setup, thus limiting investigation to a restricted region of tissue. However, studies of large-scale wavefront dynamics, especially those during fibrillation and defibrillation, would benefit from visualization of the entire epicardial surface. To solve this problem, a panoramic cardiac visualization algorithm was developed which performs the two tasks of reconstruction of the surface geometry of the heart, and representation of the panoramic fluorescence information as a texture mapping onto the geometry that was previously created. This system permits measurement of epicardial electrodynamics over a geometrically realistic representation of the actual heart being studied. To verify the accuracy of the algorithm, the procedure was applied to synthetic images of a patterned ball; further verification was provided by application of the algorithm to a model heart placed in the experimental setup. Both sets of images produced mean registration image errors on the order of 2 pixels, corresponding to roughly 3 mm on the geometry. The authors demonstrate the algorithm by visualizing epicardial wavefronts on an isolated, perfused rabbit heart.