Fenestral pore size in the internal elastic lamina affects transmural flowdistribution in the artery wall

Interstitial flow through the subendothelial intima and media of an artery wall was simulated numerically to investigate the water flow distribution t hrough fenestral pores which affects the wall shear stress on smooth muscle cells right beneath the internal elastic lamina (IEL). A two-dimensional a nalysis using the Brinkman model of porous media flow was performed. It was observed that the hydraulic permeability of the intimal layer should be mu ch greater than that of the media in older to predict a reasonable magnitud e for the pressure drop across the subendothelial intima and IEL (about 23 mostly at a 70 mm Hg luminal pressure). When K-i was set equal to the value in the media, this pressure drop was unrealistically high. Furthermore, th e higher value of K-i produced a nearly uniform distribution of water flow through a simple array of fenestral pores ah having the same diameters (1.2 mum), whereas when K-i was set at the value in the media, the flow distrib ution through fenestral pores was highly nonuniform and nonphysiologic. A d eformable intima model predicted a nonuniform flow distribution at high pre ssure (180 mmHg). Damage to the IEL was simulated by introducing a large fe nestral pore (up to 17.8 mum) into the array. A dramatic increase in flow t hrough the large pore was observed implying an altered fluid mechanical env ironment on the smooth muscle cells near the large pore which has implicati ons for intimal hyperplasia and atherosclerosis. The model also predicted t hat the fluid shear stress on the bottom surface of an endothelial cell is on the order of 10 dyne/cm(2) a level which can affect cell function. (C) 2 001 Biomedical Engineering Society.