Left atrial reservoir, conduit, and booster LA function in relation to the cardiac cycle (top) with the corresponding LA volume curves during these phases (bottom). The maximal volume (Vmax) at end-systole just before the opening of the mitral valve, minimal volume (Vmin) at end-diastole before mitral valve closure, and the volume before atrial contraction (VpreA) before mitral valve reopening at the time of the P wave on ECG. TASV is Vmax − Vmin and the AASV is the VpreA − Vmin, which represents the LA booster phase.