Abdominal Aortic Emergencies

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Key points

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    Acute aortic syndrome is a group of diagnoses, including aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer. These have similar risk factors, including hypertension and dyslipidemia, as well as comparable presentations.

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    Aortic aneurysm can be a precursor to dissection and rupture. Close surveillance and risk factor modification are key to prevention of aneurysm progression.

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    Aortic endoleak and aortoenteric fistula can be either primary processes or, more commonly, a

Acute aortic syndrome

Acute aortic syndrome (AAS) encompasses a constellation of conditions that have a similar presentation. These pathologic conditions include aortic dissection (AD), intramural hematoma (IMH), and penetrating atherosclerotic ulcer (PAU).

Each of these diseases is described in detail in the following sections. Common features of these conditions are discussed, including risk factors and classification systems used to categorize them.

Definition

A true aortic aneurysm is defined as dilation of all the layers (intima, media, and adventitia) of the aortic wall. False aneurysms, also known as pseudoaneurysms, occur when the intima is disrupted and blood is contained by the adventitia and periadventitial tissues. This section focuses exclusively on true aneurysms.

Abdominal aortic aneurysms (AAAs) are classified based on their location: supraceliac, juxtarenal, infrarenal, and aortoiliac. In addition, these aneurysms can be categorized

Definition

Abdominal aortic rupture occurs when there is a tear in all 3 layers of the wall of the aorta. This leads to massive internal bleeding. Most AAAs rupture into the retroperitoneal space (88%), a few rupture into the intraperitoneal cavity (12%), and rarely rupture can occur into the duodenum or inferior vena cava.17 Approximately 98% of ruptures occur infrarenally. The media layer of the aorta, where the strength of the aortic structure lies, contains elastic lamellae (which make up lamellar

Definition

Aortic aneurysm endoleak is related to the acute expansion of aneurysm secondary to vessel dilatation and subsequent increased vessel wall tension. Although the purpose of endovascular repair of an aortic aneurysm is to prevent rupture and subsequent mortality, at least 1% of patients experience aortic rupture postrepair annually.19 It has been hypothesized that this risk of subsequent rupture is related to the complexities of the prior aortic aneurysm, as well as endoleaks and endotension.19

Definition

Acute aortic occlusion occurs through 3 mechanisms: (1) saddle embolus to the distal infrarenal aorta, (2) in situ thrombosis of the abdominal aorta, or (3) thrombosis of the infrarenal AAA.24 Other types of emboli are rare causes of acute aortic occlusion, and these include emboli from infections such as echinococcus.12

Approximately 85% of these emboli are cardiac in origin (ie, secondary to ventricular wall motion abnormalities in acute coronary syndrome, atrial fibrillation, or valvular

Definition

An aortoenteric fistula is an erosion of a portion of the aorta that is adjacent to a portion of the gastrointestinal tract. This can be either a primary event related to an AAA or a secondary event postoperatively after aortic repair, which is more common. Primary aortoenteric fistula typically arises from an atherosclerotic aneurysm but can also originate from gastric ulcers, gastrointestinal foreign bodies, intestinal carcinoma, gallstones, or diverticulitis.12 The postoperative fistula

Summary

Diseases of the abdominal aorta represent a category of pathologic conditions that can have catastrophic consequences for the patient. These are high-risk diagnoses and are often difficult diagnoses to make given that they can present with nonspecific and vague symptoms. By understanding common risk factors and features of each of these abdominal aortic diseases, the emergency medicine provider will develop an appropriate level of clinical suspicion for these diagnoses. With consideration of

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    Financial Disclosures: The authors have nothing to disclose.

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