Wall pressure gradient in normal left coronary artery tree.

The three-dimensional wall pressure gradient (WPG) of the normal human left coronary artery (LCA) tree is quantitatively analysed. A model LCA tree, based on averaged human data set extracted from angiographies was adopted for finite-element analysis. The LCA tree includes the left main coronary artery (LMCA), the left anterior descending (LAD), the left circumflex artery (LCxA) and their major branches. The WPG is calculated using 44,452 nodes throughout the tree extension. The governing flow equations were solved using a validated numerical code. WPG as well as wall shear stress gradient (WSSG) were calculated at all available bifurcation regions. In proximal LCA tree regions where atherosclerosis frequently occurs, low WPG appears. At distal segments, WPG increases substantially due to increased velocity resulted from increased vessel tapering. Low WPG occurs at bifurcations in regions opposite the apexes, which are anatomic sites predisposed for atherosclerotic development. Endothelial cells respond to the combined effects of locally low WPG and low WSSG and provide a mechanism promoting atherosclerosis. This computational work determines probably for the first time the topography of the WPG in the normal human LCA tree. Spatial WPG differentiation indicates that locally low values of this physical parameter probably correlate to atherosclerosis localization.