Rupture of vasa vasorum and intramural hematoma of the aorta: a changing paradigm Ruptura dos vasa vasorum e hematoma intramural da aorta: um paradigma em mudança

Vasa vasorum (VV) are small arteries which penetrate the arterial wall both through the luminal surface (vasa vasorum internae) and the adventitia (vasa vasorum externae). Adventitial VV ramify into smaller vessels supplying the outer media layers. Venous VV are more numerous and also supply mainly the outer media. In humans, arteries containing less than 29 cellular layers or less than 0.5 mm diameter do not present VV.1,2 Thanks to microcomputerized tomography, tridimensional study of these vessels became possible,3,4 as well as microarteriography have enabled a more thorough understanding of their anatomy and distribution5 through the injection of a silicone polymer (Microfil®, Flow Tech, U.S.). VV seem to play a fundamental role in the physiopathology of the three acute aortic syndrome entities: aortic dissection, intramural hematoma (IMH), and penetrating ulcer. VV reactivity