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The term acute aortic syndrome has been introduced to the literature and encompasses a number of life-threatening aortic emergencies.1 These include aortic dissection, penetrating atherosclerotic ulcer, intramural hematoma, and aortic aneurysmal leakage or ruptured abdominal aortic aneurysm (see Chapter 63, Aneurysms of the Aorta and Major Arteries).

Acute aortic syndromes are uncommon but frequently fatal. In a study of 14,000 cases,2 the incidence was 16 per 100,000 for men and 9 per 100,000 for women. The 1-year, 5-year, and 10-year mortality was 92%, 77%, and 57%, respectively, for operative patients. Twenty-two percent of cases were undiagnosed prior to death. The most common cardiovascular complication of Marfan syndrome is aortic root disease3 and type A dissection (ascending aorta). Patients with a history of cardiac surgery are an important subgroup of the dissection population.

Acute aortic syndromes occur in the setting of chronic hypertension and other factors that lead to degeneration of the media of the aortic wall. Bicuspid aortic valve, Marfan syndrome, Ehlers-Danlos syndrome, and familial history of aortic dissection all predispose to aortic syndromes. All mechanisms involve weakening of the medial layer that leads to higher intimal wall stress. Response to stress may include aortic dilation, aneurysm formation, development of a penetrating ulcer, intramural hemorrhage, aortic dissection, and rupture.

Aortic dissection occurs after a violation of the intima allows blood to enter the media and dissect between the intimal and adventitial layers. The dissecting column of blood forms a false lumen and may extend proximally, distally, or both. Blood may dissect and reenter the intima, and this may clinically suggest a spontaneous cure. Alternatively the blood may dissect through the adventitia, which nearly always proves fatal.

Aortic dissection has a bimodal age distribution. The group accounting for the first peak consists of younger patients with specific predisposing conditions. The larger group accounting for the second peak is comprised of those aged >50 years with chronic hypertension. Other atherosclerotic risk factors appear to be only minor contributors to pathogenesis of acute aortic syndromes.

Aortic dissections have been classified using two separate systems. The Stanford classification considers any involvement of the ascending aorta a type A dissection. Stanford type B dissections are restricted to only the descending aorta. DeBakey type 1 dissections simultaneously involve the ascending aorta, the arch, and the descending aorta. DeBakey type 2 dissections involve only the ascending aorta and type 3, only the descending aorta.

Krukenberg originally described intramural hematoma in the 1920s. It has been more frequently described in the surgical and radiology literature in the last 10 years. An aortic intramural hematoma results from infarction of the aortic media, usually from injury to the vasa vasorum.4 An intramural hematoma may resolve spontaneously or may progress and extend. Intramural hematoma is often a precursor to dissection.5

Penetrating atherosclerotic ulcer was originally described in 1934 and has also ...

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