The Influence of Pressure and Temperature on the Behavior of the Human Aorta and Carotid Arteries

Abstract

The thermomechanical behavior of human arteries is still not well characterized despite its importance for understanding arterial physiology, and for evaluating and improving surgical procedures. The aim of this study was to provide, for the first time, experimental data illustrating how the mechanical responses of two types of human artery -the carotid artery and the aorta- are affected by changes in temperature. The mechanical properties of the arteries were derived in vitro from internal pressure-external diameter curves measured at four different temperatures (i.e., 17, 27, 37 and 42 degree C). Coefficients of expansion and stiffness were obtained by thermomechanical analysis. The condition of the arterial wall was determined histologically. The aorta and the carotid artery became slightly more compliant as the temperature increased. In both vessels, the coefficient of expansion depended critically on internal pressure. At low pressures, the coefficient of expansion was negative (i.e., the vessel contracted when heated), whereas close to a specific threshold pressure, which is different for each type of artery, the coefficient became positive. The mechanical behavior of arteries is affected by the combination of internal pressure and temperature. Consequently, the effect of this combination should be taken into account in clinical situations involving a change in temperature. Moreover, the strength of the effect depends on the type of artery under study. As a result, more detailed experimental data focusing on vessels of clinical interest are required.