A Computational Study of Renal Artery Aneurysms and Possible Arterial Occlusions Leading to Renovascular Hypertension

Linden A. Heflin, Dimitrios Papavassiliou, and Edgar O'Rear. Chemical, Biological and Materials Engineering, University of Oklahoma, 100 E. Boyd St., T-335, Norman, OK 73019

Alterations in renal artery geometry can lead to increased systemic blood pressure. This is observed clinically in cases of renal artery stenosis, where the constriction significantly alters the hemodynamics in the artery. This is thought to be primarily due to unwarranted initiation of the renin-angiotensin-aldosterone system, a renal hormonal feed back loop that responds to changes in blood pressure. The hormonal cascade that leads to vasoconstriction is initiated by baroreceptors in the kidney that sense incoming blood pressure and release renin as needed. Unusual renal artery geometry, such as a stenosis, could lead to increased pressure losses through the artery, causing the pressure at the baroreceptors to be low, and unnecessarily initiating the cascade. However, it is not known precisely what variations in renal artery geometry can induce hypertension. In addition to stenosis, renal artery aneurysms are strongly associated with renin-dependent hypertension. There is much debate over what renal artery aneurysm morphologies indicate surgical intervention, but the conversation focuses mainly on the size of, or symptoms associated with, the aneurysm. The results of multiple pulsatile flow simulations show that for some aneurysm geometries, high pressure within the aneurysm could cause the weakened artery wall to be forced into the blood stream, creating a blockage. This work seeks to investigate a new hypothesis to describe the relationship between renal artery aneurysms and renin-dependent hypertension.