Acute Aneurysm is more Critical than Acute Stenoses in Blood Vessels: a Numerical Investigation Using Stress Markers

Abstract

Diseases of blood vessels are mostly associated with stenoses and aneurysm. Secondary stenoses is an associated condition in both cases. Numerical analysis of hemodynamic in diseased blood vessel was done to evaluate probability of development of secondary stenoses. Relevant viscosity models were considered at disease conditions. Patient-specific profile was considered to represent velocity at inlet of geometry. This velocity profile was transformed to Womersley form prior to application. SIMPLE method was used for correction of pressure, whereas blood rheology was considered as non-Newtonian. Elasticity of vessel was neglected as vessels become more rigid in diseased artery. Continuity and momentum equations were solved for pressure and velocity interpolation throughout entire flow field. Flow in downstream; near boundary walls induced secondary vortices in stenosed vessels, whereas its criticality increased in aneurismal vessel. Oscillatory Shear Index (OSI) and Relative Residence Time (RRT) were formulated along endothelial lining to identify dead regions. Spatial distribution of RRT along vessel wall varied with variations in viscosity model of active fluid (such as Power Law or Quemada model). Simultaneously, OSI and RRT got modulated with change in flow rate. Centerline velocity gets modulated at far downstream from diseased section in comparison to near downstream. Numerical study based on stress parameters shows that vessels with acute aneurysm were more prone to secondary stenoses than vessels with stenoses. Thus, based on numerical results, order of priority for treatment of aneurismal vessels with acute conditions should be made for those showing dual symptoms of diseases in blood vessels.