Annual number of American Journal of Physiology-Heart publications from 1993 to 2020 that used excitation-contraction uncoupling agents [CytoD, BDM (DAM), Bleb] in cardiac optical mapping studies. BDM, 2,3-butanedione monoxime; Bleb, blebbistatin; CytoD, cytochalasin D; DAM, diacetyl monoxime.