Velocity profiles in a 2D model of the left ventricular outflow tract, pathological case study using PIV and CFD modeling

Abstract

In the current study, we present an experimental (in vitro) 2D flow model for studying blood flow in the human left ventricular outflow tract (LVOT) and the first part of the aorta using particle image velocimetry (PIV) and computational fluid dynamics (CFD). Two cardiac pathologies were investigated in this study; 1) anterior mitral leaflet (AML) billowing, and 2) asymmetric septal hypertrophy (ASH). Each of these conditions has the potential to alter the normal direction of the flow entering the aortic valve apparatus from the LVOT and therefore place an abnormal stress distribution on the aortic valve leaflets. We found good agreement between the PIV results and the CFD calculations. The largest discrepancy between the experimental data and the numerical results was found in the recirculation zone adjacent to the left coronary leaflet. The main limitations in the current study when evaluating the clinical significance of the results are the choice of a 2D geometry with stiff and stationary walls. Keeping this in mind, our results show that AML billowing and ASH bulging alone does not alter the flow field in the LVOT dramatically. However, when the two conditions combine, we see a significant flow separation and re-circulation zone forming at the left coronary leaflet, covering half of the aortic outflow tract at peak systole.