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
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 ...