Effect of aortic taper on patterns of blood flow and wall shear stress in rabbits: association with age.
OBJECTIVE
The distribution of atherosclerotic lesions changes with age in human and rabbit aortas. We investigated if this can be explained by changes in patterns of blood flow and wall shear stress.


METHODS
The luminal geometry of thoracic aortas from immature and mature rabbits was obtained by micro-CT of vascular corrosion casts. Blood flow was computed and average maps of wall shear stress were derived.


RESULTS
The branch anatomy of the aortic arch varied widely between animals. Wall shear was increased downstream and to a lesser extent upstream of intercostal branch ostia, and a stripe of high shear was located on the dorsal descending aortic wall. The stripe was associated with two vortices generated by aortic arch curvature; their persistence into the descending aorta depended on aortic taper and was more pronounced in mature geometries. These results were not sensitive to the modelling assumptions.


CONCLUSIONS
Blood flow characteristics in the rabbit aorta were affected by the degree of taper, which tends to increase with age in the aortic arch and strengthens secondary flows into the descending aorta. Previously-observed lesion distributions correlated better with high than low shear, and age-related changes around branch ostia were not explained by the flow patterns.
Department of Aeronautics, Imperial College London, South Kensington Campus, United Kingdom. v.peiffer09@imperial.ac.uk
Véronique
V
Peiffer
Ethan M
EM
Rowland
Stephanie G
SG
Cremers
Peter D
PD
Weinberg
Spencer J
SJ
Sherwin
D000367:Age Factors; D000375:Aging / Q000473:pathology; D000818:Animals; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D001018:Aortic Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D001783:Blood Flow Velocity; D003198:Computer Simulation; D016319:Corrosion Casting; D006439:Hemodynamics; D057446:Hydrodynamics; D008955:Models, Cardiovascular; D011817:Rabbits; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D055114:X-Ray Microtomography