TY - JOUR
T1 - Physical and computational fluid dynamics models for the hemodynamics of the artiodactyl carotid rete
AU - O'Brien, Haley D.
AU - Bourke, Jason
N1 - Funding Information:
We thank the Ohio University Student Enhancement Award & Graduate Student Senate Original Work Grants (HDO & JB), the American Society of Mammalogists Grants-In-Aid program (HDO) , the Society for Integrative and Comparative Biology Grants-In-Aid program (HDO) , and fellowships from the Ohio Center for Ecology and Evolutionary Studies (HDO) and the National Science Foundation Graduate Research Fellowship (JB) , for funding this research. S.H. Williams loaned the specimen of Capra used in this study, and L.M. Witmer and H. Skinner-Rockhold conducted CT scanning at O’Bleness Memorial Hospital in Athens, Ohio. We thank Dr. Denise Kirschner and an anonymous reviewer, as well as N.J. Stevens, R.E. Klabunde, and P.M. Gignac for helpful comments on the manuscript.
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2015/12/7
Y1 - 2015/12/7
N2 - In the mammalian order Artiodactyla, the majority of arterial blood entering the intracranial cavity is supplied by a large arterial meshwork called the carotid rete. This vascular structure functionally replaces the internal carotid artery. Extensive experimentation has demonstrated that the artiodactyl carotid rete drives one of the most effective selective brain cooling mechanisms among terrestrial vertebrates. Less well understood is the impact that the unique morphology of the carotid rete may have on the hemodynamics of blood flow to the cerebrum. It has been hypothesized that, relative to the tubular internal carotid arteries of most other vertebrates, the highly convoluted morphology of the carotid rete may increase resistance to flow during extreme changes in cerebral blood pressure, essentially protecting the brain by acting as a resistor. We test this hypothesis by employing simple and complex physical models to a 3D surface rendering of the carotid rete of the domestic goat, Capra hircus. First, we modeled the potential for increased resistance across the carotid rete using an electrical circuit analog. The extensive branching of the rete equates to a parallel circuit that is bound in series by single tubular arteries, both upstream and downstream. This method calculated a near-zero increase in resistance across the rete. Because basic equations do not incorporate drag, shear-stress, and turbulence, we used computational fluid dynamics to simulate the impact of these computationally intensive factors on resistance. Ultimately, both simple and complex models demonstrated negligible changes in resistance and blood pressure across the arterial meshwork. We further tested the resistive potential of the carotid rete by simulating blood pressures known to occur in giraffes. Based on these models, we found resistance (and blood pressure mitigation as a whole) to be an unlikely function for the artiodactyl carotid rete.
AB - In the mammalian order Artiodactyla, the majority of arterial blood entering the intracranial cavity is supplied by a large arterial meshwork called the carotid rete. This vascular structure functionally replaces the internal carotid artery. Extensive experimentation has demonstrated that the artiodactyl carotid rete drives one of the most effective selective brain cooling mechanisms among terrestrial vertebrates. Less well understood is the impact that the unique morphology of the carotid rete may have on the hemodynamics of blood flow to the cerebrum. It has been hypothesized that, relative to the tubular internal carotid arteries of most other vertebrates, the highly convoluted morphology of the carotid rete may increase resistance to flow during extreme changes in cerebral blood pressure, essentially protecting the brain by acting as a resistor. We test this hypothesis by employing simple and complex physical models to a 3D surface rendering of the carotid rete of the domestic goat, Capra hircus. First, we modeled the potential for increased resistance across the carotid rete using an electrical circuit analog. The extensive branching of the rete equates to a parallel circuit that is bound in series by single tubular arteries, both upstream and downstream. This method calculated a near-zero increase in resistance across the rete. Because basic equations do not incorporate drag, shear-stress, and turbulence, we used computational fluid dynamics to simulate the impact of these computationally intensive factors on resistance. Ultimately, both simple and complex models demonstrated negligible changes in resistance and blood pressure across the arterial meshwork. We further tested the resistive potential of the carotid rete by simulating blood pressures known to occur in giraffes. Based on these models, we found resistance (and blood pressure mitigation as a whole) to be an unlikely function for the artiodactyl carotid rete.
KW - Artiodactyla
KW - Carotid rete
KW - Computational fluid dynamics
KW - Hagen-Poiseuille's equation
KW - Hemodynamics
UR - http://www.scopus.com/inward/record.url?scp=84943226504&partnerID=8YFLogxK
U2 - 10.1016/j.jtbi.2015.09.008
DO - 10.1016/j.jtbi.2015.09.008
M3 - Article
C2 - 26403501
AN - SCOPUS:84943226504
SN - 0022-5193
VL - 386
SP - 122
EP - 131
JO - Journal of Theoretical Biology
JF - Journal of Theoretical Biology
ER -