Flow–area relationship in internal carotid and vertebral arteries

Abstract

Subject-specific computational and experimental models of hemodynamics in cerebral aneurysms require the specification of physiologic flow conditions. Because patient-specific flow data is not always available, researchers have used "typical" or population average flow rates and waveforms. However, in order to be able to compare the magnitude of hemodynamic variables between different aneurysms or groups of aneurysms (e.g. ruptured vs. unruptured) it is necessary to scale the flow rates to the area of the inflow artery. In this work, a relationship between flow rates and vessel areas is derived from phase-contrast magnetic resonance measurements in the internal carotid arteries and vertebral arteries of normal subjects.

Effects of Flow-Diverting Device Oversizing on Hemodynamics Alteration in Cerebral Aneurysms

“…12 Because patient-specific flow conditions were not available, typical flow waveforms measured in healthy subjects were used to specify the inflow boundary conditions. 13 Two sets of flow conditions were used for each model. The first (denoted flow 1) corresponds to a mean flow of 3 mL/s and a peak flow of 5 mL/s.…”

3D Computational Fluid Dynamics of a Treated Vertebrobasilar Giant Aneurysm: A Multistage Analysis

“…All of the inlets were defined as mass-flow inlets on which the mass-flow rate was defined so that the main flow rate in the basilar artery was 200 mL/min (Fig 2). 20,27 All of the outlets were defined as the outflow boundaries on which the diffusion flux for any variable was zero. Either for the inlets or for the outlets, the flow rates were distributed proportionally to the corresponding cross-sectional areas of the inlet or outlet boundaries.…”

Flow structures in cerebral aneurysms

“…Convergence criterion was set to 10 −8 on the residual. The vessel wall was assumed rigid and the fluid boundary conditions were chosen to be no-slip for the vessel wall, a zero pressure gradient was prescribed at the outflows (including for the secondary vessel for Case 2) and the inflow flow rate was obtained using the relation Q = k · A n (where k = 48.21 and n = 1.84) [31]. The cross-sectional areas of both cases was found to be almost identical, resulting in a Q = 4 × 10 −6 m 3 /s, hence Re ≈ 260.…”