Acute aortic dissection: Microenvironmental regulation

With the exception of certain genetic connective tissue disorders, acute aortic dissections are still often thought to occur randomly. Very few of these events fall under the genetic category such as Marfan's disease, Ehlers Danlos type IV or Loeys Dietz syndrome and the vast majority follows the rules of other catastrophic vascular events. The evidence is mounting that these catastrophes do not happen at random. This brief review looks at the evidence regarding a circadian, seasonal and weekly rhythm particularly of acute aortic dissections but also other vascular events including their association with emotional stress. The recent surge of interest in aortic diseases and particularly the establishment of the IRAD registry have lead to new insights and clarification of these events. While hormonal associations with vascular events have been known for more than thirty years, modern molecular examinations about regulatory pathways are mostly still lacking. The steering of circadian variation is accepted but poorly understood. On the basis of vascular neuroimmunological observations, speculations regarding micro environmental regulatory pathways are offered.