Acute aortic syndromes

Class I – Classic dissection with separation of intima/media and dual lumens; there is a flap between true and false aneurysm and clot in false lumen.
Class II – Intramural hematoma with separation of intima/media but no intraluminal tear or flap on imaging.
Class III – Limited intimal tear without hematoma and eccentric bulge at tear site (limited dissection).
Class IV – Atherosclerotic ulcer penetrating to adventitia with surrounding hematoma that is usually subadventitial.
Class V – Iatrogenic or traumatic dissection (eg, due to a cardiac catheterization).