Role of the Bloodstream Impacting Force and the Local Pressure Elevation in the Rupture of Cerebral Aneurysms

Abstract

Background and Purpose-Inertial force of the bloodstream results in the local elevation of intravascular pressure secondary to flow impact. Previous studies suggest that this "impacting force" and the local pressure elevation at the aneurysm may have a large contribution to the development of cerebral aneurysms. The goal of the present study is to evaluate how the bloodstream impacting force and the local pressure elevation at the aneurysm influences the rupture of cerebral aneurysms. Methods-A total of 29 aneurysms were created in 26 patient-specific vessel models, and computer simulations were used to calculate pressure distributions around the vessel branching points and the aneurysms. Results-Direct impact of the parent artery bloodstream resulted in local elevation in pressure at branch points, and bends in arteries (231.2Ϯ198.1 Pa; 100 Paϭ0.75 mm Hg). The bloodstream entered into the aneurysm with a decreased velocity after it impacted on the branching points or bends. Thus, the flow impact at the aneurysm occurred usually weakly. At the top or the rupture point of the aneurysm, the flow velocity was always delayed. The local pressure elevation at the aneurysm was 119.3Ϯ91.2 Pa. Conclusions-The pressure elevation at the area of flow impact and at the aneurysm constituted only 1% to 2% of the peak intravascular pressure. The results suggest that the bloodstream impacting force and the local pressure elevation at the aneurysm may have less contribution to the rupture of cerebral aneurysms than was expected previously.

Rest versus Exercise Hemodynamics for Middle Cerebral Artery Aneurysms: A Computational Study

“…Hence for structural analyses, the assumption of a spatially uniform pressure field is appropriate. In Shojima et al, 23 it is suggested that loading applied by the pulsatile inflow jet is insignificant in comparison with the loading imparted by the transmural pressure. Although this may be the case regarding purely mechanical (structural) loading, we must note that there is growing evidence that such small pressure differences (due to impingement for example) may have significant implications in terms of biologic processes, remodelling, growth, and rupture.…”

Quantitative Hemodynamic Analysis of Brain Aneurysms at Different Locations

“…8 Intra-aneurysmal hemodynamic characteristics are also believed to be an important factor for aneurysm growth and rupture. [9][10][11][12][13][14][15][16] With the help of advancements in medical imaging, realistic aneurysm geometry and vascular structure can be incorporated into simulations to perform patient-specific hemodynamic analysis. This type of image-based hemodynamic research has shown that ruptured aneurysms tend to have a more complicated flow pattern.…”

Biomechanical Factors Analysis in Aneurysm

“…This extra pressure is the force responsible for focal degeneration of the internal elastic membrane and thus the cause of initiation of aneurysms at the apex. Shojima et al (2005) reported that local rises in pressure due to flow impingement are less than 2 mmHg, which is small compared with nominal pressure levels in cerebral arteries, and concluded that dynamic pressures acting at bifurcations and on the walls of intracranial arteries may be less significant to enlargement and rupture than previously assumed. Acevedo-Bolton et al (2006) concluded that regions that continued to enlarge experienced low wall shear stress and speculated that this might be due to increased residence time of particles that degrade the aneurysm wall.…”