Abstract 99: Computational Fluid Dynamics of CT Angiography in SAMMPRIS Reveal Blood Flow and Vessel Interactions in Middle Cerebral Artery Stenoses

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
David S Liebeskind ◽  
Fabien Scalzo ◽  
Graham W Woolf ◽  
Justin M Zubak ◽  
George A Cotsonis ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Middle Cerebral Artery ◽  
Ct Angiography ◽  
Cerebral Artery ◽  
Intraluminal Pressure ◽  
Intracranial Atherosclerosis ◽  
Fractional Flow

Background: Noninvasive fractional flow measures with CT angiography (CTA) have revolutionized cardiology, yet the complex anatomy of the cerebral circulation and boundary conditions challenge the study of intracranial atherosclerosis. We developed a framework for systematic computational fluid dynamics (CFD) of middle cerebral artery (MCA) stenosis with CTA in SAMMPRIS. Methods: A 3D geometric mesh was generated from CTA source images, followed by CFD processing in Ansys (ICEM, CFX) on a Cray supercomputer. Reference boundary conditions were applied with an ICA inlet and outlets at the ACA and distal MCA to yield quantitative maps of intraluminal pressure drops (ΔP or fractional flow), blood flow velocity (V) and turbulent kinetic energy (TKE) with wall shear stress (WSS) mapped along the arteries. CFD parameters were then compared with SAMMPRIS angiography variables. Results: Of 451 SAMMPRIS (70-99% symptomatic stenosis) subjects, CTA was acquired at enrollment in 41 MCA cases. CFD results were successfully attained in 30, limited by anatomy (e.g. across branch points) in 7/11 and poor CTA resolution in 4/11. Fractional flow (ΔP) across stenosis was mean 0.64 ± SD 0.33, with maximal stenosis velocity of mean 192 ± SD 101 cm/s and maximal WSS 0.36 ± SD 0.25 mm Hg. SAMMPRIS angiography percent stenosis was unrelated to ΔP -0.163 (p=0.399), velocity 0.126 (p=0.514) or WSS 0.078 (p=0.689). Worse collateral blood flow grades were associated with larger ΔP (p=0.137), higher velocity (p=0.059), higher WSS (p=0.112). Asymmetric WSS with high and low regions on opposing arterial walls was measured in the post-stenotic segment in 25/30 (83%). TKE maps revealed focal increases in the post-stenotic region, yet not above abnormal thresholds based on arterial diameter. Conclusions: CTA CFD of intracranial atherosclerosis provides detailed noninvasive measures of hemodynamics.

scholarly journals A Simple Transient Poiseuille-Based Approach to Mimic the Womersley Function and to Model Pulsatile Blood Flow

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 9-17
Author(s):  
Andrea Natale Impiombato ◽  
Giorgio La Civita ◽  
Francesco Orlandi ◽  
Flavia Schwarz Franceschini Zinani ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Quadratic Function ◽  
Pulsatile Blood Flow ◽  
Flow Through ◽  
Simplified Analysis ◽  
Function Models ◽  
Flow Reversals

As it is known, the Womersley function models velocity as a function of radius and time. It has been widely used to simulate the pulsatile blood flow through circular ducts. In this context, the present study is focused on the introduction of a simple function as an approximation of the Womersley function in order to evaluate its accuracy. This approximation consists of a simple quadratic function, suitable to be implemented in most commercial and non-commercial computational fluid dynamics codes, without the aid of external mathematical libraries. The Womersley function and the new function have been implemented here as boundary conditions in OpenFOAM ESI software (v.1906). The discrepancy between the obtained results proved to be within 0.7%, which fully validates the calculation approach implemented here. This approach is valid when a simplified analysis of the system is pointed out, in which flow reversals are not contemplated.

An Immersed Porous Boundary Method for Computational Fluid Dynamics of Blood Flow in Aneurysms With Flow Diverters

2012 ◽  
Author(s):  
Viorel Mihalef ◽  
Puneet Sharma ◽  
Ali Kamen ◽  
Thomas Redel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Artery ◽  
Intracranial Aneurysms ◽  
Mortality Rates ◽  
Morbidity And Mortality ◽  
High Morbidity ◽  
Flow Diverters

Intracranial aneurysms are pathological dilatations of a cerebral artery that may suffer rupture and lead to subarachnoid hemorrhage. Such a condition presents high morbidity and mortality rates for the patients concerned.

Use of Computational Fluid Dynamics for the Replication of Clinical Blood Flow and Pressure Measurements and Characterization of Hemodynamics in the Normal Ascending and Thoracic Aorta

2007 ◽  
Author(s):  
John F. LaDisa ◽  
C. Alberto Figueroa ◽  
Irene E. Vignon-Clementel ◽  
Frandics P. Chan ◽  
Jeffrey A. Feinstein ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Thoracic Aorta ◽  
Vascular Anatomy ◽  
Data Set ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd

Complications associated with abnormalities of the ascending and thoracic aorta are directly influenced by mechanical forces. To understand hemodynamic alterations associated with diseases in this region, however, we must first characterize related indices during normal conditions. Computational fluid dynamics (CFD) models of the ascending and thoracic aorta to date have only provided descriptions of the velocity field using idealized representations of the vasculature, a single patient data set, and outlet boundary conditions that do not replicate physiologic blood flow and pressure. Importantly, the complexity of aortic flow patterns, limited availability of methods for implementing appropriate boundary conditions, and ability to replicate vascular anatomy all contribute to the difficulty of the problem and, likely, the scarcity of more detailed studies.

Hemodynamic Features of Microsurgically Identified, Thin-Walled Regions of Unruptured Middle Cerebral Artery Aneurysms Characterized Using Computational Fluid Dynamics

Neurosurgery ◽  
2019 ◽  
Vol 86 (6) ◽  
pp. 851-859
Author(s):  
Jang Hun Kim ◽  
Huan Han ◽  
Young-June Moon ◽  
Sangil Suh ◽  
Taek-Hyun Kwon ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Intracranial Aneurysms ◽  
Microscopic Surgery ◽  
Unruptured Intracranial Aneurysms ◽  
Thin Walled ◽  
Cfd Analyses ◽  
Middle Cerebral Artery Aneurysms

Abstract BACKGROUND Thin-walled regions (TWRs) of aneurysm surfaces observed in microscopic surgery are thought to be vulnerable areas for growth and rupture of unruptured intracranial aneurysms (UIAs). OBJECTIVE To identify hemodynamic features of TWRs of aneurysms by using computational fluid dynamics (CFD) analyses of unruptured middle cerebral artery bifurcation (MCAB) aneurysms. METHODS Nine patients with 11 MCAB aneurysms were enrolled, and their TWRs were identified. CFD analysis was performed using 3 parameters: pressure, wall shear stress (WSS), and WSS divergence (WSSD). Each parameter was evaluated for its correspondence with TWR. RESULTS Among 11 aneurysms, 15 TWRs were identified. Corresponding matches with CFD parameters (pressure, WSS, and WSSD) were 73.33, 46.67, and 86.67%, respectively. CONCLUSION WSSD, a hemodynamic parameter that accounts for both magnitude and directionality of WSS, showed the highest correspondence. High WSSD might correspond with TWR of intracranial aneurysms, which are likely high-risk areas for rupture.

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