Abstract WMP36: Wall Shear Stress Disturbances May Be Key Requirements for Cerebral Aneurysm Growth: Computational Flow Dynamic Analysis of 15 Cases in NHO CFD ABO Study

Abstract

Introduction: In 2013, we conducted a multi-institutional prospective observational study in order to identify hemodynamic environments involved in the rupture and growth of unruptured cerebral aneurysms by computational fluid dynamic (CFD) analysis (National Hospital Organization CFD ABO Study: UMIN000013584). There were 461 cases registered and observed for 3 years on the condition that 3DCTA and carotid echocardiography were performed every year. The observation period ended at the end of March this year. There were 32 cases that enlarged, and 209 cases that did not enlarge or rupture after 3 years of observation period. Here, 15 growing cases and 15 non-growing cases were hemodynamically evaluated. Methods: Pulsatile blood flow was simulated using ANSYS-CFX, based on the Navier-Stokes equations for incompressible fluid. Multivariate regression analysis was performed to find differences between growing and non-growing aneurysms in wall shear stress (WSS) magnitude-based metrics (WSS, WSSG, NWSS, NWSSG) and WSS disturbance-based metrics (OSI as a metric for unidirectional WSS disturbance, NtransWSS as a metric for multi-directional WSS disturbance)on the CFD modelling after adjustment for age, sex, hypertension, smoking history, and aneurysm size and location. Results and Conclusions: In the growing and non-growing aneurysms, the average age was 71.8 ± 12.6 and 66.3 ± 11.1 years, the maximum diameter 5.48 ± 2.64 and 5.47 ± 1.85 mm, female 10 and 6 cases, HT 10 and 10, smoking 6 and 11, respectively. Both OSI (p=0.0215) and NtransWSS (p=0.0428) were significantly higher in growing aneurysms compared to non-growing ones, whereas there were no significant differences in WSS magnitude-based metrics(figure). The data suggested that WSS disturbances may be closely associated with the growth of cerebral aneurysms.