Figure 3.

Time-resolved myocardial wall stress. The first panel shows the ejection-phase aortic pressure and myocardial wall stress (MWS) profiles. The second panel shows the time-resolved relative myocardial geometry (ratio of wall volume to cavity volume) that correlates with wall stress via the Laplace law; the first, second, and last thirds of systole are shown in blue, dotted red, and black lines, respectively. The third panel shows the ejection-phase myocardial wall stress, and the fourth panel shows pressure–MWS relation. It can be seen that myocardial wall stress peaks in early systole and subsequently decreases, even in the context of increasing pressure. This is due to a mid-systolic shift in the pressure–stress relation (dashed arrow) which favours lower MWS for any given pressure. This shift is due to the geometric reconfiguration of the LV (decreased cavity volume relative to LV wall volume) and is impaired in the presence of reductions in LV ejection fraction, concentric geometric remodelling, and reduced early systolic ejection (reduced early-phase ejection fraction). LV, left ventricular.