Fig. 3

Simulation of mechanical dyssynchrony in a two-compartment ventricular model. Ventricles in a two-compartment ventricular model are schematized in a. Delayed activation by ΔT ms was applied to a part of the ventricular volume corresponding to a part of the wall area (colored in blue) associated with the ventricular outflow. Gray double arrows represent an inter-compartment flow (clinically called as intraventricular flow). Time–volume relations during a cardiac cycle with an activation delay (ΔT, ms) are shown in b. Orange and blue vertical lines, yellow and blue areas, or superimposed gray areas represent contraction onsets, ventricular volume changes at every moment of earlier and delayed compartment, or inter-compartment flow, respectively. Both the activation delay by ΔT (top to bottom row) and the ratio of the delayed compartment affect ventricular mechanics. A monophasic contraction of the earlier activated compartment with relatively large volume (green arrows) is noted when the ratio of the delayed compartment is 10% or 30%. A preceding volume reduction followed by a systolic stretch (red arrow) can be detected when the ratio of the delayed compartment is 70%, at which ratio an inter-compartment reverse flow is noted in early and late systole (black triangles). This swinging flow is similar to representative Doppler velocity signal at ventricular septal defect in a patient with codominant-type single ventricle (white triangles, c)