Sub-cellular spatially concordant [Ca2+]i alternans - oscillation of calcium concentration within the myocyte such that [Ca2+] within all sub-cellular areas oscillates in-phase (i.e. all sub-cellular regions demonstrate high or low [Ca2+]).
Sub-cellular spatially discordant [Ca2+]i alternans - oscillation of calcium concentration within the myocyte such that [Ca2+] within adjacent sub-cellular areas oscillates out-of-phase (i.e. some sub-cellular regions demonstrate high [Ca2+] and adjacent sub-cellular regions demonstrate low [Ca2+]).
Cellular concordant [Ca2+]i and AP alternans - oscillation of intracellular calcium concentration and AP voltage such that these signals are in-phase (i.e. a large [Ca2+]i corresponds to a long APD and vice versa).
Cellular discordant [Ca2+]i and AP alternans - oscillation of intracellular calcium concentration and AP voltage such that these signals are out-of-phase (i.e. a large [Ca2+]i corresponds to a short APD and vice versa).
Tissue/whole heart spatially concordant APD alternans – oscillation of action potential duration such that adjacent areas of the heart are in-phase (i.e. adjacent regions demonstrate either long or short APDs).
Tissue/whole heart spatially discordant APD alternans - oscillation of action potential duration such that adjacent areas of the heart are out-of-phase (i.e. one area of the heart demonstrates long APDs while an adjacent area demonstrates short APDs).
