Numerical investigation of renal artery hemodynamics based on the physiological response to renal artery stenosis

Renal Artery Stenosis (RAS) is the narrowing of renal arteries, most often caused by atherosclerosis or fibromuscular dysplasia. Possible complications of renal artery stenosis are renovascular hypertension and renal ischemia. The goals of the current study were to investigate the physiological response to RAS and effects of the artery and stenosis geometry, quantify the performance of arterial pressure regulation mechanisms respect to stenosis severity, and predict future conditions of renal artery stenosis. Commercial software based on the finite volume method was utilized to solve governing equations. To determine the physiological response, simulations were done for two cases, with and without the involvement of arterial pressure regulation mechanisms. The numerical method was validated by experimental data, which obtained from two prototypes. Results showed that systemic blood pressure was increased as the physiological response to RAS; hence, the flow rate of the renal branch was improved and renal ischemia was relatively prevented. Furthermore, results demonstrated that the stenosis percentage and artery diameter were dominant geometric parameters on the hemodynamics and other parameters had negligible effects. It was demonstrated that 50% of stenosis was the critical point for the interaction of RAS and arterial pressure regulation mechanisms. Finally, wall shear stress was analyzed on an image-based geometry, and it was estimated and expected that acute renal artery stenosis was progressive and pathogenesis of arterial diseases.