Aortic dissection is a disease of the vasa vasorum

Associate Editor's Introduction—Understanding the initiating event of an acute aortic syndrome is made difficult by the inability to observe the process play out in the early stages of development; clinically, we are left with the result of whatever occurred. A “grand unified theory” of aortic disease would ideally link acute aortic dissection (AAD) and intramural hematoma (IMH) in a continuum of the same process (and, for that matter, penetrating aortic ulcers). It is easy to accept that IMH is a variant of AAD when we are unable to identify the primary intimal tear.