Arcades are blood vessels that form direct connections between two arteries or arterioles. Because they are supplied with blood from two sources, arcades can function as alternative flow pathways following obstruction of arteries or arterioles, as in coronary and peripheral vascular disease and stroke. In response to changes in blood flow or metabolic conditions, vascular networks undergo structural adaptation or remodeling, which includes structural changes of the existing vessels and growth of new vessels. Following obstruction of a blood supply, arcade vessels may adjust their internal diameters chronically to convert the alternative pathways into main blood distribution vessels. The overall goal of this dissertation was to examine structural changes in the internal diameter of a single arcade artery and the arterioles of an arcade network following changes in blood flow, using experimental and theoretical approaches. Diameter changes of the mouse gracilis arcade artery were observed up to 56 days following resection of one of its two blood supplies. Overall, diameters increased to a maximum around day 21 and then declined. The diameter changes were spatially non-uniform, being largest towards the point of resection, providing transiently increased perfusion to the most affected regions. Observed diameter changes were compared with predictions of a theoretical model, in which diameter varies in response to stimuli derived from local metabolic and hemodynamic conditions. Good agreement was found when effects of a time-delayed growth stimulus in regions of reduced perfusion were included, with a delay of about 7 days. The effectiveness of arcades in maintaining perfusion both immediately following obstruction and after structural adaptation in the arteriolar arcade network between two feed artery branches of the pig triceps brachii muscle was examined. Morphometric data from vascular casting and published data were used to develop a computational model for the hemodynamics and structural adaptation of the network in response to local stimuli. The results show that the arcades provide alternative flow pathways to the region initially supplied by the obstructed branch and that structural adaptation can lead to improved flow restoration following interruption of blood flow.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/280607 |
| Date | January 2004 |
| Creators | Gruionu, Gabriel |
| Contributors | Secomb, Timothy W. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Dissertation-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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