Quantitative haemodynamic study in renal artery bifurcation using CFD

Computational Fluid Dynamics facilitates in the quantitative analysis of haemodynamic processes of in vivo cardiovascular systems. The objective of the present study is to examine the effects of different branching angles of diseased renal arteries with respect to the abdominal aorta on its flow characteristics. Secondly, simulation of normal renal arteries at similar branching angles were also done as a baseline for comparison to comprehend if geometry played a role in the endothelial proliferation in renal artery stenosis. Idealistic renal artery models generated from the digital image of computerized tomography scan were used, with bifurcation angles at the junction ranging from 30° to 90° at successive intervals of 15°. Virtual stenosis of a degree below and above 80% by diameter were generated on the right and left renal artery respectively. The models were discretized using a hybrid polyhedral mesh. Parameters such as time-averaged velocity, time-averaged wall shear stress, pressure difference and fractional flow reserve were used to analyse the flow characteristics. Stenosed renal arteries with higher angulation was found to have larger flow recirculation zones, higher pressure gradient near the Ostia and was observed to experience greater amounts of shear stress at the region of stenosis. For the same degree of stenosis (above 80%), the blockage tended to increase from 18% to 25%, as the angle increased. The effect of angulation was observed to alter the flow characteristics significantly in the stenosed arteries. Critically stenosed (above 80%) renal arteries at a bifurcation angle above 45° showed signs of ischemia.