The Dynamic Topography of the Blood-Contacting Surface of Arteries

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

When segments of arteries are removed from the body, they have a distinct, corrugated appearance on the inside. It has long been assumed that this is a result of the artery deflating as the effect of blood pressure is removed. The investigators in this project hypothesize that the corrugations actually play a role in normal, physiological function and that they change significantly due to normal changes in arterial pressure and diameter. This hypothesis will be studied through a combination of experimental and modeling techniques. The researchers will answer questions about the underlying biomechanics of these corrugations as well as how they vary with normal physiological function and along the length of the arterial structure within the body. The knowledge gained will significantly impact fundamental understanding of arterial biomechanics and their physiological function. It may also inform future development of improved replacement arterial graft designs for treatment of injured or diseased arteries. The research will be conducted by a unique research team that includes medical residents as well as graduate and undergraduate students. This will support the engineers ability to connect the engineering research to the actual physiology and potential clinical impact. In addition, modules on arterial mechanics and the underlying materials performance will be developed as part of a series of lecture-demonstration activities that provide K12 students with a visual understanding of the science. Three aims have been established to test the stated hypothesis. First, the team will investigate the biomechanics of the luminal corrugations by treating the internal elastic lamina (the inner surface) as a thin, nearly-inextensible membrane in contact with a soft substrate. Second, the dynamic topography of the arteries will be investigated to understand the state of the corrugations under normal physiologic conditions. Finally, the variation in luminal structure and corrugations will be investigated for arteries as they move distal to (away from) the heart. This work will use a combination of imaging and biomechanical testing strategies in both in vivo and excised arteries from porcine specimens, and the biomechanical behavior will be related to the collagen and elastin microstructure. The experiments will be partnered with finite element models that will be used to understand the underlying mechanisms of the biomechanical behavior as well as, once validated, investigate varying loads and boundary conditions that cannot easily be studied experimentally. If the primary hypothesis is supported, the investigators plan to link their findings to the secondary hypothesis that the functional role of the corrugations is to protect the endothelial layer of the artery by allowing it to accommodate the arterial diameter changes without in-plane stretching. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.