  Aortic Aneurysms are among the most critical cardiovascular diseases. The
present study is focused on Ascending Thoracic Aortic Aneurysms (ATAA). The
main causes of ATAA are commonly cardiac malformations like bicuspid aor-tic
valve or genetic mutations. Research studies dedicated to ATAA tend more and
more to invoke multifactorial eects. In the current review, we show that all
these eects converge towards a single paradigm relying upon the crucial
biome-chanical role played by smooth muscle cells (SMCs) in controlling the
distribution of mechanical stresses across the aortic wall. The chapter is
organized as follows. In section 6.2, we introduce the basics of arterial wall
biomechanics and how the stresses are distributed across its dierent layers and
among the main structural constituents: collagen, elastin, and SMCs. In section
6.3, we introduce the biome-chanical active role of SMCs and its main
regulators. We show how SMCs actively regulate the distribution of stresses
across the aortic wall and among the main structural constituents. In section
6.4, we review studies showing that SMCs tend to have a preferred homeostatic
tension. We show that mechanosensing can be understood as a reaction to
homeostasis unbalance of SMC tension. Through the use of layer-specic
multiscale modeling of the arterial wall, it is revealed that the quantication
of SMC homeostatic tension is crucial to predict numerically the initiation and
development of ATAA.
