Shown is an example of anatomic no-reflow detected by vital staining in an experimental rabbit model of coronary occlusion and reperfusion. In Panel A, 4 short-axis slices are shown depicting the regions perfused and stained by monastral blue, which was injected during coronary occlusion. Regions which were not perfused by the dye (i.e. do not stain blue) represent the risk area. In Panel B, the slices were imaged under UV light to depict the fluorescent areas (greenish color) stained by thioflavin-S, which was injected following reperfusion and stains intact endothelium. The thioflavin-S negative regions represent no-reflow,are contained within and are smaller than the risk region. Hence, thioflavin-S negative areas depict regions of obstruction to flow despite reperfusion . Reprinted with permission from Reffelmann T, Kloner R A Heart 2002;87:163.