Acute aortic syndrome is an acute lesion of the aortic wall involving the aortic media. The term covers aortic dissection, intramural hematoma, and penetrating ulcer. In the last few years, imaging techniques have increased our understanding of the natural history of these disease entities and of the dynamics of the disease processes. Despite significant advances in diagnosis and surgical treatment, the mortality rate in the acute phase remains high. Early clinical suspicion and greater surgical expertise appear to be the only factors that are able reduce mortality. Once the acute phase is past, the descending aorta continues to be involved in most patients, 30 % of whom develop complications within 3-5 years. During this later phase, it is...