Local Hemodynamic Conditions Associate with Focal Changes in the Intracranial Aneurysm Wall

BACKGROUND AND PURPOSE: Aneurysm hemodynamics has been associated with wall histology and inflammation. We now investigated associations between local hemodynamics and focal wall changes visible intra-operatively. METHODS: Computational fluid dynamics models were constructed from 3D images of 65 aneurysms treated surgically. Aneurysm regions with different visual appearances were identified in intra-operative videos: 1) “atherosclerotic” (yellow), 2) “hyperplastic” (white), 3) “thin” (red), 4) rupture site, and 5) “normal” (similar to parent artery) and marked on 3D reconstructions. Regional hemodynamics was characterized by: wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), WSS gradient and divergence, gradient oscillatory number (GON), and dynamic pressure (PRE); and compared with the Mann-Whitney test. RESULTS: Hyperplastic regions had lower average WSS (p=0.005) and pressure (p=0.009) than normal regions. Flow conditions in atherosclerotic and hyperplastic regions were similar, but had higher average RRT (p=0.03), and OSI (p=0.04) than thin regions. Hyperplastic regions also had higher average GON (p=0.002) than thin regions. Thin regions had lower average RRT (p