Analysis of complex flow and the relationship between blood pressure, wall shear stress, and intima-media thickness in the human carotid artery.
BACKGROUND
Previous clinical studies have observed relationships between increased intima-media thickness (IMT) in the carotid artery, elevated blood pressure, and low wall shear stress (WSS) calculated from the Poiseuille equation. This study used numerical methods to more accurately determine WSS in the carotid artery and to investigate possible determinants of increased IMT.


METHODS
IMT [common carotid artery (CCA) and bulb], CCA flow velocity, brachial systolic (SBP) and diastolic blood pressure (DBP), and carotid systolic pressure (cSBP) were measured in 14 healthy subjects (aged 44 +/- 16 yr). Flow patterns in the carotid bifurcation were determined by computational fluid dynamics (CFD) based on three-dimensional ultrasound geometry. Instantaneous and time-averaged wall shear stress (WSS(av)), oscillatory shear index (OSI), and wall shear stress angle gradients (WSSAG) were calculated.


RESULTS
IMT was positively related to SBP, DBP, cSBP, and WSSAG and inversely related to WSS(av) in the CCA. In the bulb, IMT was positively related to SBP and cSBP but was not significantly related to WSS(av) or WSSAG. IMT was unrelated to OSI in both the CCA and the bulb.


CONCLUSIONS
Increased carotid artery IMT in healthy subjects with no evidence of focal plaques is primarily a response to elevated pressure.
Augst
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AD
Department of Chemical Engineering, Faculty of Engineering, Imperial College London, UK.
Ariff
B
B
McG Thom
S A G
SA
Xu
X Y
XY
Hughes
A D
AD
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D001916:Brachial Artery / Q000502:physiology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D018056:Hemorheology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D012016:Reference Values; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D013997:Time Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging; D017540:Tunica Media / Q000000981:diagnostic imaging; D014463:Ultrasonography