Management of Acute Aortic Syndromes

Perspective:

The following are 10 points to remember about acute aortic syndromes (AAS):

1. AAS consists of inter-related emergency conditions with similar clinical characteristics and includes aortic dissection, intramural hematoma (IMH), and penetrating atherosclerotic ulcer (PAU). Trauma to the aorta with intimal laceration may also be considered an AAS.

2. The common denominator of AAS is disruption of the aortic media with bleeding along the wall of the aorta resulting in separation of the layers of the aorta (dissection), or transmurally through the wall in the case of ruptured PAU or trauma. In the majority of patients (90%), an intimal disruption is present that results in tracking of the blood in a dissection plane within the media.

3. The most common aortic syndrome is aortic dissection. The classic hallmark of this entity is a tear in the aortic intima, which is commonly preceded by medial wall degeneration or cystic media necrosis. Blood flows through the tear separating the intima from media or adventitia creating a false lumen, and this can then propagate in an anterograde or retrograde fashion. Clinical presentation of this syndrome is impacted by the location of the initial tear, involvement of side branches, and complications such as tamponade, aortic valve, insufficiency, or malperfusion syndromes.

4. The most common risk factor for aortic dissection or IMH is hypertension, and 75% of patients with AAS have a history of hypertension. Other risk factors include smoking, direct blunt trauma, and the use of illicit drugs such as cocaine or amphetamines. The incidence of acute dissection ranges from 2 to 3.5 cases per 100,000 person-years.

5. The most common cause of traumatic aortic dissection or rupture is road traffic accidents or deceleration trauma. Among patients dying in road accidents, 20% have a ruptured aorta. The most common site of aortic tear is the aortic isthmus (45%), followed by the ascending aorta (23%).

6. Pain is the most common presenting symptom among patients with AAS, and its localization and associated symptoms reflect the location of the initial disruption, and change as the dissection extends along the aorta.

7. The risk of death is increased in patients with cardiac tamponade, or involvement of coronary or cerebral vessels, with resultant cardiac or cerebral ischemia. In the absence of immediate surgical repair, medical management of proximal dissection is associated with a mortality of 20% by 24 hours after presentation and 50% by 1 month. In patients undergoing surgical repair, mortality rates are 10% at 24 hours, and 20% at 30 days. The 30-day mortality of a type B dissection is 10%, but is as high as 25% in patients who develop ischemic complications.

8. AAS (dissection or IMH) involving the ascending aorta are surgical emergencies, while those confined to the descending aorta are treated medically unless complicated by organ or limb malperfusion, progressive dissection, extra-aortic blood collection (impending rupture), intractable pain, or uncontrolled hypertension. Endovascular therapy is emerging as the preferred therapy for patients with type B dissections if they fail medical therapy.

9. Initial treatment of all patients with aortic dissection is focused on reducing pulse pressure to just maintain sufficient end-organ perfusion with the use of intravenous beta-blockade as first-line therapy. Labetalol is a particularly efficacious agent, although multiple agents are often required.

10. The 10-year survival rate of patients with AAS who leave the hospital ranges from 30-60%. These patients need careful long-term follow-up with aggressive control of hypertension, beta-blockers to minimize aortic wall stress, and serial imaging to detect signs of progression, redissection, or aneurysm formation.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Pericardial Disease, Prevention, Vascular Medicine, Interventions and Vascular Medicine, Hypertension, Smoking

Keywords: Labetalol, Follow-Up Studies, Blood Pressure, Risk Factors, Pain, Tunica Intima, Deceleration, Endothelium, Cocaine, Street Drugs, Cerebral Infarction, Survival Rate, Hypertension, Lacerations, Disease Progression, Hematoma, Brain Ischemia, Angioplasty, Smoking, Ulcer, Adventitia, Tunica Media, Cardiac Tamponade


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