Abstract W P77: Ruptured Aneurysms Tend To Have Prominent Blood Flow Changes At Aneurysm Neck

Introduction: Hemodynamics is thought to play an important role in the pathogenesis, progression, and rupture of aneurysms. Reports have suggested that aneurysm rupture, regardless of aneurysm size, may be due to the collision of incoming flow forming a prominent jet stream directed towards the aneurysm head. The objective of this study was to gain insight into the effect of aneurysm neck, body, and dome cross section geometries on local flow rates. Hypothesis: Aneurysm neck, body, and dome cross section geometries affect local flow rates within the aneurysm head. Methods: Blood flow through the aneurysm neck, body, and dome were evaluated with respect to the cross section size of each region in 33 cases of ruptured posterior communicating artery aneurysms. Computational fluid dynamic analysis was performed and quantitative hemodynamic variables were extracted from the simulation results. Results: All aneurysms generally experienced similar incoming systole volumetric flow rates regardless of the inlet cross-section geometry. Aneurysms with smaller necks experienced greater and more uniform flow reductions than medium or large sized necks. The overall reductions of flow volume through the neck for small, medium, and large necks were 97.8 ±1.4%, 90.0 ±2.7%, and 41.1±22.4%, respectively. Blood flow through the aneurysm body was not affected by body size in small and medium cross sections but still appeared to have some dependence on the aneurysm neck size. Aneurysms with large body geometries, however, further experienced flow reductions of 99.1 ±0.43%. Aneurysm dome cross section size was not found to have a significant effect on volumetric flow rate. Conclusion: Regardless of shape, we found that certain aneurysm neck, body, and dome cross section sizes may have a large influence on flow reduction and energy transmission to the aneurysm apex. By analyzing a group of ruptured aneurysm cases, we found small aneurysms necks have the most drastic flow changes, indicating that aneurysm neck shape may be important for clinical assessment of rupture risk.