The long term objective is to understand the role of hemodynamics in the pathogenesis and development of atherosclerosis. Towards this objective, experiments will be carried out to elucidate the early response of the arterial wall to its hemodynamic environment. Particular emphasis is placed on the influence of arterial elasticity on the flow field near the intimal surface. Compliant, transparent flow-through casts will be made from minimally diseased human aortic bifurcations, using compliance measurements in the original vessel as a guide. The cast will be perfused in a flow tunnel that is designed to expose the model to a pulsatile flow and luminal pressures that are physiologically realistic. Velocities near the cast wall will be measured noninvasively at selected sites by laser Doppler anemometry. The fluid mechanical data will be correlated against pathological and histological measurements, obtained by gross observation and light microscopy, at corresponding sites in the vessel from which the cast was made. The data analysis will include, but is not limited to, an examination of the relationship between wall shear stress, calculated from near-wall velocity measurements, and intimal thickness. In some cases, multiple casts, having different compliances, will be made from a single luminal mold. The compliances will be representative of real arteries at various stages in the aging process. In a limited number of these cases, a rigid cast will also be prepared from the mold. Velocity measurements at corresponding sites in each set of models will be used to assess quantitatively - and in a realistic geometry - the influence of arterial elasticity on the hemodynamic environment of the vascular wall. This is an interdisciplinary research project, in which the fluid mechanical experiments and data reduction are carried out at the Applied Physics Laboratory, and the pathological and histological studies are performed at the School of Medicine.
