Effects of thoracic epidural anesthesia (TEA) on electrical wave dynamics and dispersion of repolarization in a representative animal. Top, Polar maps of activation recovery interval (ARI) at baseline are unchanged pre- and post-TEA. Bottom, ARI heterogeneity or dispersion of repolarization is greatly increased with left stellate stimulation (LSS); however TEA attenuates ARI dispersion. LAD = left anterior descending.