The standard methodology is to reocclude the coronary artery before perfusing the heart with a vital dye (typically Evans blue) or microspheres. This stains the remote myocardium but leaves the AAR unstained. In a second step, nonviable myocardium within the AAR is identified using triphenyltetrazolium chloride (TTC) staining. This colorless dye is reduced to a deep-red precipitate by dehydrogenases in the presence of NADH (4, 7). Since lethally damaged cells do not retain these reactants, nonviable areas remain unstained and appear pale, whereas viable cells stain red. Some practical information on common protocols can be found in the methods sections of research papers or online, e.g., at http://www.southalabama.edu/ishr/help/ttc/.