An Experiment-Based Model of Vein Graft Remodeling Induced by Shear Stress

Abstract

Vein graft intimal hyperplasia induced by shear stress is considered to be one of the major causes of vein graft failure. We have developed a mathematical model of vein graft intimal hyperplasia induced by shear stress based on experimental data. Intimal thickness and the rate of intimal thickness change are expressed as functions of shear stress and time. The model coefficients are derived from animal experiments where bilateral rabbit carotid vein grafts are exposed to different shear stress levels. Morphology data of the vein grafts are obtained over multiple time points. The model describes the well-known behavior of intimal thickening, which is inversely related to shear stress. It also depicts the time-dependent behavior of vein graft intimal hyperplasia. Finally, the model is used to simulate the intimal growth around a focal stenosis, which was created by ligating the middle of a vein graft using a suture. Simulation results and experimental data agree qualitatively, and demonstrate that the intima thickens more distal to the stenosed area. These experiments establish the potential of the general experiment-based approach for predicting human vein graft remodeling. Other mechanical and biological factors can be included following a similar approach in order to obtain a more accurate vein graft remodeling model.