Objective-Isolated common iliac artery aneurysms (CIAA) are rare. Their prognosis and influence on aortoiliac blood flow and remodeling are unclear. We evaluated the hypotheses that morphology at and distal to the aortic bifurcation, together with the associated hemodynamic changes, influence both the natural history of CIAA and proximal aortic remodeling.
Approach and Results-Twenty-five isolated CIAAs (15 intact, 10 ruptured), in 23 patients were reconstructed and analyzed with computational fluid dynamics: all showed abnormal flow. Then we studied a series of 24 hypothetical aortoiliac geometries in silico with varying abdominal aortic deflection and aortic bifurcation angles: key findings were assessed in an independent validation cohort of 162 patients. Wall shear stress in isolated unilateral CIAAs was lower than the contralateral common iliac artery, 0.38 +/- 0.33 Pa versus 0.61 +/- 0.24 Pa, inversely associated with CIAA diameter (P
Conclusions-Decreasing wall shear stress is strongly associated with CIAA progression (larger aneurysms and rupture), whereas abnormal blood flow in the CIAA seems to promote proximal aortic remodeling, with adaptive lateral deflection of the abdominal aorta towards the aneurysmal side.
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