Head posture influences the geometric and hemodynamic features on the healthy human carotid bifurcation

Atherosclerosis is the third leading cause of morbidity and mortality in the Western world. Low and oscillating wall shear stress (WSS) regions have been previously reported as parameters that correlate with the development of atherosclerosis. In this study we investigated geometric and hemodynamic changes in the carotid bifurcation as a result of posture change. Data from magnetic resonance imaging (MRI) were used to construct three dimensional (3D) surface models and computational fluid dynamic (CFD) fields. Two healthy volunteers were imaged by MRI in three different head postures: a) the supine neutral (N) head position, b) the prone position with leftward head rotation (LR) up to 80° and c) the prone position with rightward head rotation (RR) up to 80o. The area exposure to unfavorable hemodynamics, based on thresholds set for oscillatory shear index (OSI), WSS and relative residence times (RRT), was used to quantify the hemodynamic impact on the wall. Significant change in the hemodynamic burden on the wall was found for the OSI. The velocity profile at the common carotid artery (CCA) upstream of the carotid bifurcation (CB) was investigated at the supine and RR prone position for six healthy volunteers. The results indicated that blood flow rate decreased at peak systole, for the prone position for both the right and left CCAs

Head posture influences the geometric and hemodynamic features on the healthy human carotid bifurcation

Atherosclerosis is the third leading cause of morbidity and mortality in the Western world. Low and oscillating wall shear stress (WSS) regions have been previously reported as parameters that correlate with the development of atherosclerosis. In this study we investigated geometric and hemodynamic changes in the carotid bifurcation as a result of posture change. Data from magnetic resonance imaging (MRI) were used to construct three dimensional (3D) surface models and computational fluid dynamic (CFD) fields. Two healthy volunteers were imaged by MRI in three different head postures: a) the supine neutral (N) head position, b) the prone position with leftward head rotation (LR) up to 80° and c) the prone position with rightward head rotation (RR) up to 80o. The area exposure to unfavorable hemodynamics, based on thresholds set for oscillatory shear index (OSI), WSS and relative residence times (RRT), was used to quantify the hemodynamic impact on the wall. Significant change in the hemodynamic burden on the wall was found for the OSI. The velocity profile at the common carotid artery (CCA) upstream of the carotid bifurcation (CB) was investigated at the supine and RR prone position for six healthy volunteers. The results indicated that blood flow rate decreased at peak systole, for the prone position for both the right and left CCAs

CFD challenge: Solutions using the commercial finite volume solver, fluent

This work is a collaborative effort between the Biomechanics and Living System Analysis Laboratory (BIOLISYS) in Cyprus and the Biomechanics Laboratory of IACM/FORTH in Greece. Both labs combine interdisciplinary skills from engineering, medicine and biology to provide solutions to clinical problems associated with cardiovascular and other diseases. For this study, numerical flow simulations were performed using: a) open source software VMTK and commercial software ICEM CFD as pre-processors, b) the finite volume based solver Fluent and c) Tecplot 360 (Amtec Inc.) for post-processing

CFD challenge: Solutions using the commercial finite volume solver, fluent

This work is a collaborative effort between the Biomechanics and Living System Analysis Laboratory (BIOLISYS) in Cyprus and the Biomechanics Laboratory of IACM/FORTH in Greece. Both labs combine interdisciplinary skills from engineering, medicine and biology to provide solutions to clinical problems associated with cardiovascular and other diseases. For this study, numerical flow simulations were performed using: a) open source software VMTK and commercial software ICEM CFD as pre-processors, b) the finite volume based solver Fluent and c) Tecplot 360 (Amtec Inc.) for post-processing

Effect of Head Posture on the Healthy Human Carotid Bifurcation Hemodynamics

Head and neck postures may cause morphology changes to the geometry of the carotid bifurcation (CB) that alter the low and oscillating wall shear stress (WSS) regions previously reported as important in the development of atherosclerosis. Here the right and left CB were imaged by MRI in two healthy subjects in the neutral head posture with the subject in the supine position and in two other head postures with the subject in the prone position: (1) rightward rotation up to 80°, and (2) leftward rotation up to 80°. Image-based computational models were constructed to investigate the effect of posture on arterial geometry and local hemodynamics. The area exposure to unfavorable hemodynamics, based on thresholds set for oscillatory shear index (OSI), WSS and relative residence time, was used to quantify the hemodynamic impact on the wall. Torsion of the head was found to: (1) cause notable changes in the bifurcation and internal carotid artery angles and, in most cases, on cross-sectional area ratios for common, internal and external carotid artery, (2) change the spatial distribution of wall regions exposed to unfavorable hemodynamics, and (3) cause a marked change in the hemodynamic burden on the wall when the OSI was considered. These findings suggest that head posture may be associated with the genesis and development of atherosclerotic disease as well as complications in stenotic and stented vessels