Congratulations to BSL postdoc Yiemeng Hoi, whose paper "Correlation between local hemodynamics and lesion distribution in a novel aortic regurgitation murine model of atherosclerosis" has been published by the Annals of Biomedical Engineering. (And kudos to Springer: two weeks from acceptance to online-first publication!)Our co-authors had previously demonstrated that the induction of aortic regurgitation accelerates the formation of atherosclerotic lesions in Ldlr-/- mice -- lesions whose distinct and consistent spatial localization suggested a strong local hemodynamic influence. Building upon this work, and with painstaking care, Yiemeng reconstructed the geometry of the mouse aorta from micro-CT of a cast vessel; derived the necessary flow rate boundary conditions from Doppler ultrasound measurements and literature values; and ensured that the process of mapping the CFD predictions for comparison with en face plaque stainings was fair and unbiased.
Our main result, summarized in the figure above, shows that the distinctive distributions of plaque can indeed be explained by the patterns of high oscillatory shear index (OSI) and/or long relative residence times (RRT). Control CFD studies using normal flow rates and straightened geometry confirm that these focal hotspots arise from the combination of the anatomical curvatures of the mouse aorta and the strong retrograde flow rates of the AR mice. On the other hand, time-averaged shear magnitude (TAWSS), the usual suspect, does not explain the plaque distributions, showing that, when it comes to "disturbed" flow, "low and oscillatory" need not always go hand in hand. (I know, I know, that's a lot of hands.)
