Fluid mechanic analysis is used to create and implement a metric to quantify the effectiveness of plaque removal (i.e., debulking) modalities in small arteries. The quantification is based on a three-dimensional, unsteady model of blood flow in complex tubular geometries which characterizes plaque-narrowed arteries. Blood flow unsteadiness is due to the heart-imposed temporal variations which occur during the cardiac cycle. The arterial geometries used for the analysis were determined by the reconstruction Of Ultrasonic images which were captured before and after debulking. Numerical simulation was used to implement the fluid mechanic model, and separate consideration is given to Newtonian and non-Newtonian constitutive equations. The results of the analysis indicates that the removal of the plaque led to an increase in the rate of blood flow of approximately 2.5, both during the systole and diastole portions of the cardiac cycle. This increase corresponds to the application of the same time-varying, end-to-end pressure difference across the artery segments. The shear stress on the artery wall, a major determinant of the buildup of plaque, is found to be higher for a debulked artery than for a plaque-narrowed artery. This outcome is favorable in that the higher the wall shear, the lower the rate of plaque formation. (C) 2008 Elsevier Ltd. All rights reserved.