Intra-aneurysmal pressure and flow changes induced by flow diverters: relation to aneurysm size and shape

Larrabide, Ignacio, 1978-; Aguilar, María Laura; Morales, Hernán G.; Geers, Adrianus Johannes; Kulcsár, Zsolt; Rüfenacht, Daniel; Frangi Caregnato, Alejandro

doi:http://dx.doi.org/10.3174/ajnr.A3288

Intra-aneurysmal pressure and flow changes induced by flow diverters: relation to aneurysm size and shape

Citation

Larrabide I, Aguilar ML, Morales H, Geers A, Kulcsár Z, Rüfenacht D, et al. Intra-aneurysmal pressure and flow changes induced by flow diverters: relation to aneurysm size and shape. American Journal of Neuroradiology. 2013 Apr 1;34(4):816-22. DOI: 10.3174/ajnr.A3288

Abstract

Background and purpose: Effects of blood flow modification by flow diverters are observed to lead often to aneurysm thrombosis and reverse remodeling. For this process, to further understand the potential roles of intra-aneurysmal blood pressure changes and aneurysm morphologies, 23 patients were studied by numeric simulation. Materials and methods: 3D imaging of aneurysms of different sizes and shapes, all located at the supraclinoid segment of the ICA (n = 23), was prepared for CFD simulations. Hemodynamic variables were calculated for conditions before and after virtual FD implantation, reconstituting a vessel wall scaffold across the aneurysm neck. WSS, velocity, residence time, turnover time, and intra-aneurysmal pressure were assessed statistically. Results: After placement of FDs, significant reductions inside the aneurysm were observed for most hemodynamic variables (P < .01) except mean intra-aneurysmal pressures. For minimum/maximum intra-aneurysmal pressure values, small but significant changes were found; however, they were considered too small to be of relevance. Conclusions: Calculations in 23 cases did not reveal significant intra-aneurysmal mean or peak pressure changes, indicating a minor role of pressure changes in the rare event of secondary ruptures after FD use. Other hemodynamic variables (WSS and velocity) exhibited more significant changes, indicating their role in intra-aneurysmal thrombus formation. Size-dependent, significantly higher reduction in WSS (P = .069) and velocity (P = .013) was observed in small aneurysms compared with larger ones. When it came to shape, there were significantly higher reductions in WSS (P = .055) and velocity (P = .065) and a significantly higher increase in turnover time in fusiform aneurysms compared with saccular aneurysms.