The perivascular environment along the vertebral artery governs segment-specific structural and mechanical properties.
The vertebral arteries (VAs) are anatomically divided into four segments (V1-V4), which cumulatively transport blood flow through neck and ultimately form the posterior circulation of the brain. The vital physiological function of these conduit vessels depends on their geometry, composition and mechanical properties, all of which may vary among the defined arterial segments. Despite their significant role in blood circulation and susceptibility to injury, few studies have focused on characterizing the mechanical properties of VAs, and none have investigated the potential for segmental variation that could arise due to distinct perivascular environments. In this study, we compare the passive mechanical response of the central, juxtaposed arterial segments of porcine VAs (V2and V3) via inflation-extension mechanical testing. Obtained experimental data and histological measures of arterial wall composition were used to adjust parameters of structure-motivated constitutive models that quantify the passive mechanical properties of each arterial segment and enable prediction of wall stress distributions under physiologic loads and boundary conditions. Our findings reveal significant segmental differences in the arterial wall geometry and structure. Nevertheless, similar wall stress distributions are predicted in these neighboring arterial segments if calculations account for their specific perivascular environments. These findings allow speculation that segmental differences in wall structure and geometry are a consequence of a previously introduced principle of optimal operation of arteries, which ensures effective bearing of physiological load and a favorable mechanical environment for mechanosensitive vascular smooth muscle cells.



Among the numerous biomechanical investigations devoted to conduit blood vessels, only a few deal with vertebral arteries. While these studies provide useful information that describes the vessel mechanical response, they do not enable identification of a constitutive formulation of the mechanical properties of the vessel wall. This is an important distinction, as a constitutive material model is required to calculate the local stress environment of mechanosensitive vascular cells and fully understand the mechanical implications of both vascular injury and clinical intervention. Moreover, segmental differences in the mechanical properties of the vertebral arteries could be used to discriminate among distinct modes of injury and disease etiologies.
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States.
Boran
B
Zhou
Medical University of South Carolina, Department of Neurosurgery, Charleston, SC 29425, United States.
Mohammed
M
Alshareef
University of South Carolina School of Medicine, Department of Cell Biology and Anatomy, Columbia, SC 29205, United States.
David
D
Prim
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States.
Michael
M
Collins
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States.
Michaela
M
Kempner
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States; University of South Carolina School of Medicine, Department of Cell Biology and Anatomy, Columbia, SC 29205, United States.
Adam
A
Hartstone-Rose
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States; University of South Carolina School of Medicine, Department of Cell Biology and Anatomy, Columbia, SC 29205, United States.
John F
JF
Eberth
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States; Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Alexander
A
Rachev
University of South Carolina, College of Engineering and Computing, Biomedical Engineering Program, Columbia, SC 29208, United States; College of Engineering and Computing, Mechanical Engineering Department, University of South Carolina, Columbia, SC 29208, United States. Electronic address: shazly@mailbox.sc.edu.
Tarek
T
Shazly
D000818:Animals; D001696:Biomechanical Phenomena; D008297:Male; D008962:Models, Theoretical; D011312:Pressure; D013314:Stress, Mechanical; D034421:Sus scrofa; D014711:Vertebral Artery / Q000033:anatomy & histology* / Q000502:physiology*
Arterial mechanics; Continuum mechanics; Elasticity; Structure-motivated constitutive model; Vertebral artery