Aortic dissection: Prompt diagnosis and emergency treatment are critical

AORTIC DISSECTION VARIANTS

Aortic intramural hematoma

Aortic intramural hematoma is a form of acute aortic syndrome in which a hematoma develops in the aortic media and no intimal flap is visualized either by imaging or at surgery.^2,3,16 It is important to recognize this clinical entity in a patient presenting with acute chest or back pain, as sometimes it is mistaken for a “thrombus in a nonaneurysmal aorta.” Intramural hematoma accounts for 5% to 25% of acute aortic syndromes, depending on the study population (it is more common in Asian studies).^2,3,17 It may present with symptoms similar to classic aortic dissection and is classified as type A or type B, depending on whether the ascending aorta is involved.

Reproduced with permission from: Braverman AC, et al. Diseases of the aorta. In: Bonow RO, et al. Braunwald's Heart Disease, 9th edition. Elsevier: Philadelphia, PA; 2011.

CT shows high-attenuation crescentic or circumferential thickening of the aortic wall on noncontrast studies and low-attenuation thickening on contrast images (Figure 5).^2,3 MRI is also highly accurate in demonstrating intramural hematoma. TEE shows aortic wall thickening with an eccentric aortic lumen and displaced intimal calcification and echolucent spaces in the aortic wall (Figure 6).

Patients with an intramural hematoma may progress to having complications such as hemopericardium, classic aortic dissection, aortic rupture, or aneurysmal dilation.^2,3 However, many cases of type B aortic intramural hematoma result in complete resorption of the hematoma over time. In general, like classic aortic dissection, type A intramural hematoma is treated with emergency surgery and type B with initial medical therapy.^2,3

There are reports from Southeast Asia of successful initial medical therapy for type A intramural hematoma, with surgery used for acute complications.¹⁸ In the Western literature, improved outcomes are reported with initial surgical therapy.¹⁷ Given the unpredictable nature of type A intramural hematoma, most experts recommend surgical therapy for appropriate candidates with acute type A intramural hematoma.^2,3,19

Penetrating atherosclerotic ulcer of the aorta

Penetrating atherosclerotic ulcer of the aorta, another acute aortic syndrome, results from acute penetration of an atherosclerotic aortic lesion through the internal elastic lamina into the media.^2,3,20 It is often associated with bleeding into the media, or intramural hematoma. While the ulcer may be found incidentally on imaging studies, especially in patients with severe aortic atherosclerosis, the typical presentation is acute, severe chest or back pain. It occurs most often in the descending aorta and the abdominal aorta.

Penetrating atherosclerotic ulcer may lead to pseudoaneurysm formation, focal aortic dissection, aortic rupture, or late aortic aneurysm.²

Reproduced with permission from: Braverman AC, et al. Diseases of the aorta. In: Bonow RO, et al. Braunwald's Heart Disease, 9th edition. Elsevier: Philadelphia, PA; 2011.

Penetrating atherosclerotic ulcer has a classic appearance on CT, MRI, and TEE, with focal ulceration and a crater-like outpouching (Figure 7). Intramural hemorrhage is often present. These lesions have a high propensity for rupture, and because of the focal nature of these lesions, they are often suitable for endovascular therapy.

LONG-TERM MANAGEMENT AFTER AORTIC DISSECTION

After hospital discharge, patients with aortic dissection require lifelong management. This includes blood pressure control, lifestyle modification, serial imaging of the aorta with CT or MRI, patient education about the condition, and, when appropriate, screening of family members for aortic disease.^5,21

Reported survival rates after hospitalization for type A dissection are 52% to 94% at 1 year and 45% to 88% at 5 years.^2,22 The 10-year actuarial survival rate for those with acute dissection who survive the acute hospitalization is reported as 30% to 60%. Long-term survival rates after acute type B dissection have been reported at 56% to 92% at 1 year and 48% to 82% at 5 years.²³ Survival rates depend on many factors, including the underlying condition, the age of the patient, and comorbidities.

It is important to treat hypertension after aortic dissection, with a goal blood pressure of 120/80 mm Hg or less for most patients. Older studies found higher mortality rates with poorly controlled hypertension. Beta-blockers are the drugs of first choice. Even in the absence of hypertension, long-term beta-blocker therapy should be used to lessen the aortic stress and force of ventricular contraction.