Arterial deformation with renal artery aneurysm as a basis for secondary hypertension.

The goal of this work is to better understand the association between renal artery aneurysms and secondary hypertension through modeling the blood flow and the mechanics of diseased arteries. A large number of patients with renal artery aneurysms exhibit hypertension. Following surgical intervention, some patients experience improvement in their hypertension while others do not. This indicates that for some patients, the aneurysm is directly related to their hypertension, possibly through a hemodynamic effect on hormonal blood pressure control. In previous work, we proposed a possible mechanism for this--that high pressure inside an aneurysm may cause the arterial wall to deform and constrict the artery, creating a "pseudostenosis". Here, we use fluid structure interaction simulations to investigate the deformation of the renal artery in the presence of an aneurysm. Aneurysms on the superior surface and at the main bifurcation of the artery have been modeled, and the effect of changes in mechanical properties and geometry were investigated. For some cases, it was found that an aneurysm could cause flow distortions that led to higher than normal pressure losses without significant vessel wall deformation. For other cases, conditions were determined that induced movement of the arterial wall with constriction of the underlying artery. The maximum occlusion observed was 54% for a symmetric aneurysm at the main bifurcation with a severely weakened wall with a Young's modulus of 1 × 10(3) Pa.