Age-related changes in the mechanical properties of arteries

A unique feature of the stiffness of large arteries is that it is one of few biological variables that more than doubles with age. Large arteries are responsible for capacitive transformation of the pulsatile ejection of the heart to a more continuous blood flow for supply of oxygen and nutrients to the body organs. Detrimental changes in mechanical properties of the large arteries decrease this capability, increasing the work load of the heart and increasing the pulsatile nature of flow to the organs with potential for end-organ damage. This chapter outlines the components of the large artery wall that give the artery mechanical strength and elasticity, describes how the stiffness of large arteries can be assessed both in vivo and ex vivo, and draws from the literature to investigate how large artery wall mechanics change with age to impact on hemodynamic parameters. Age-related functional changes include elastin fragmentation, collagen cross-linking and reduced endothelial function . Measures of large artery mechanics include vascular impedance , pulse pressure augmentation and amplification, pulse wave velocity and quantification of endothelial function. This chapter describes each of these concepts, giving the mathematical derivation and functional meaning of the parameters. The change in these parameters with age is summarized using evidence from both longitudinal and cross-sectional human population studies. With a lack of therapeutic targets currently available to halt or reverse the progression of large artery stiffness with age, current treatment methods are limited to lifestyle changes for which some evidence exists for limiting the increase in large artery stiffness.