Etiology of aortic dissection.

We discuss the etiology of aortic dissection (AD) from various points of view. The development of AD requires two pathological conditions: medial degeneration and mechanical wall stress. First, histopathological findings of medial degeneration are hypothesized to be due to a loss of elastic fibers and interconnecting elastic fibers. Damage to the vasa vasorum plays a key role in creating an entry site. The clinical causes of medial degeneration include hypertension, aortic aneurysms, obstructive sleep apnea, and connective tissue disorders. Second, mechanical wall stress is supposedly induced by shear stress caused by blood flow, together with hypertension and aortic root movement. Further investigation is necessary in the search for mechanisms responsible for medial degeneration prior to AD development.