Collagen in arterial walls: Biomechanical aspects

Abstract

This chapter is written with an emphasis on the biomechanical role of collagen in normal and diseased arterial walls, its structural quantification and its consideration in material models including phenomena such as growth and remodeling. Collagen is the ubiquitous load-bearing and reinforcing element in arterial walls and thus forms an important structural basis. The structural arrangement of collagen leads to the characteristic anisotropic behavior of the arterial wall and its respective layers. The organization of collagen fibers, and the tension within, maintains the function, integrity and strength of arteries. This chapter starts by reviewing the structure of the arterial wall and the biomechanical properties of the individual wall layers. Subsequently, structural quantifications of the collagen fabric are discussed with focus on polarized light microscopy, small-angle X-ray scattering and computer vision analysis. A basic building block for soft collagenous tissues in which the material is reinforced by one family of collagen fibers is next presented. On this basis, a structural model for arteries with an ideal alignment of collagen fibers is reviewed, and subsequently extended to consider collagen crimping and the dispersion of collagen fiber orientations. In order to capture structural modifications such as collagen reorientation, phenomenologically based microstructural and continuum models are presented which consider stress-modulated collagen remodeling. Finally, a constitutive model in which continuous remodeling of collagen is responsible for the growth of saccular cerebral aneurysms is outlined. All of the provided models have been implemented in finite element codes, and have proven to be efficient in the computational analysis of clinically relevant problems. This chapter is by no means complete, but it might help to grasp the most important biomechanical aspects of collagen in arterial tissues, and may serve as the basis for a more intense study of this fascinating topic © 2008 Springer Science+Business Media, LLC.