Effect of viscoelastic property of atherosclerotic fibrous tissue on arterial diameter variation

Arterial wall motion was analysed in the atherosclerotic plaque models to study the effect of wall tissue viscoelasticity and lipid core stiffness on wall displacement waveforms. A typical slice of the patient’s IVUS data was modelled, and the anisotropic and viscoelastic behaviour of tissue was considered. Two-dimensional transient analysis was performed using a commercial structure analysis software. The maximum radial wall displacement (DRmax) and the time delay between the pressure and displacement waveforms (DT) were increased as the relative moduli of a Prony series increased. DT was larger while DRmax was smaller for the stiffer cores. DT was suggested as an index to assess plaque wall stability, because it was decreased for the plaque with more viscous nature (higher smooth muscle cell content) and harder lipid core (lower lipid content).