Artery Wall Viscoelasticity: Measurement, Assessment, and Clinical Implications

Arteries, which carry blood from the heart to the peripheral tissues, are continuously stressed by pressure pulsation. Pathological changes in arterial walls could cause high-risk cardiovascular diseases, such as heart attack and stroke. Once established, vascular diseases progress by the continual remodeling of the arterial wall, which includes changes in the composition and function of the wall tissues. An arterial wall has both elastic and viscous characteristics, and pathological and degenerative changes in the wall tissue affect the viscoelastic behavior of the artery wall. The arterial viscoelasticity may provide useful information regarding the development and progression of arterial diseases. However, only the wall stiffness has been considered as a clinical diagnostic index for atherosclerosis. Only a few studies have assessed the viscoelasticity of an intact artery, and further studies are necessary to employ the wall viscoelasticity as a physical marker for diagnosing vascular diseases. Accordingly, this study focuses on arterial wall viscosity assessment and its possible clinical applications. In vitro and in vivo tissue viscoelasticity measurement techniques are reviewed, and constitutive models used to assess viscoelastic artery wall behaviors are summarized. Because wall viscoelasticity depends on the tissue composition and function, pathological changes in the arterial wall during atherosclerosis and the contribution of vascular cells to viscoelasticity are discussed. Finally, the recent progress in clinical tools for measuring arterial viscoelasticity is reviewed.