Biomechanical analysis of coronary arteries using a complementary energy model and designed experiments

摘要

Coronary heart disease, a manifestation of Atherosclerosis, is a significant cause of morbidity and mortality. Despite the importance of the coronary arteries, little is known about their healthy properties, or potential regional differences, or how the diseased state changes these mechanical properties. For this reason, a mathematical model that describes coronary mechanical properties is desired by the biomedical and medical communities. Such a model could help clarify the role played by mechanics in cardiovascular disease.;The study of arteries has been plagued by testing and numerical difficulties. We hypothesize that the testing method and numerical difficulties are related, and propose a different approach to mechanical experimentation and modeling. The approach utilizes techniques from the field of statistics to improve the collection and analysis of experimental data. The method uses a complementary energy function having the measurable quantities of force and pressure as independent variables, and strain values as dependent variables. Data is collected with the aid of an experimental design covering a wide range of force and pressure. The regression procedure used to fit the model parameters also relies on principles of statistics. The method uses a repeated measures approach to make use of the correlation between observation errors rather than ignore them, as done by many previous researchers. Parameters fit to the constitutive model are then compared to assess differences in mechanical response for each type of specimen.;In summary, an experimental design and mechanical and statistical analysis method were developed for the comparative study of blood vessels and, potentially, vascular grafts. Results show that there are regional differences in the mechanical response of porcine coronary arteries, using a physiological range of pressures and axial stretch. Specifically, statistically significant differences exist between the mechanical response of the left anterior descending [LAD] and the right coronary artery [RCA]; but no difference exists between the LAD and left circumflex [LCX] or the LCX and RCA. A new vascular graft was also tested and shown to be similar in mechanical response to the right coronary artery at physiologic pressures. The significance of this work for vascular graft mechanics is discussed.