Lagrangian Coherent Structure (LCS, yellow) in the left ventricle of a healthy volunteer during mid-diastole. A transparent four-chamber image of the heart is shown for orientation. Red particle traces show blood flowing into the ventricle during diastole, and blue particles show blood already in the ventricle from the previous heartbeat. Note that the yellow LCS separates the blue and red particle traces. LV: Left Ventricle, RV: Right Ventricle, LA: Left Atrium, RA: Right Atrium.