Abstract T P110: Impact Of Systolic Blood Pressure On Cerebral Hemoynamics Measure By Computational Fluid Dynamics In Patients With Intracranial Atherosclerosis

Abstract

Background: Success in clinical trials of intracranial atherosclerosis (ICAS) hinges upon the definition of high-risk patients. Noninvasive computational fluid dynamics (CFD) of stenotic lesions may enhance therapeutic decision-making, yet the wide hemodynamic variation may limit the snapshot data of CFD. We determined whether different physiologic parameters may change downstream cerebral hemodynamics in patients with ICAS. Methods: Based on degree of stenosis, patients were divided into a moderate (50-69%) and severe group (70-99%). CFD models were made using CTA source images of patients with symptomatic middle cerebral artery stenosis. Inlet boundary conditions were defined using three ranges (2.5, 50, and 97.5 percentiles) of systolic BP (109.2, 158, and 225 mmHg) and hematocrit (27.3, 40.2, and 48.8). According to systolic BP and hematocrit, 9 distinct scenarios were simulated. Ratio of pressure was calculated using the simulated pressure at pre- and post-stenotic segments. Ratio of shear strain rate (SSR) and velocity were assessed between throat and proximal normal segment. A linear mixed model was used for the statistical analysis of repeated simulations. Results: Among the 56 patients, 32 (57.1%) patients had moderate stenosis and 24 (42.9%) had severe stenosis. Patients with severe stenosis showed unfavorable hemodynamics in terms of ratio of pressure, velocity, and SSR comparing with moderate stenosis group. A linear mixed model revealed that ratio of pressure was predicted by systolic BP X stenosis group interaction (p = 0.036). These pressure drops were associated with systolic BP (p<0.001), and stenosis group (p<0.001), not with hematocrit (p = 0.337). Ratios of SSR and velocity were only associated with stenosis group. Conclusions: Downstream blood flow may be significantly altered by systolic BP along with severity of stenosis. As individual patient’s specific anatomy influences hemodynamics, physiologic conditions may superimpose further changes in post-stenotic blood flow in patients with ICAS.