Chapter 42
Aortic Emergencies

Ali S. Raja¹ and Jesse M. Pines^2,3

¹ Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA

² US Acute Care Solutions, Canton, OH, USA

³ Department of Emergency Medicine, Drexel University, Philadelphia, PA, USA

Background

Thoracic aortic dissection and abdominal aortic aneurysm (AAA) are the two aortic emergencies most commonly seen in emergency department (ED) patients. Rupture of AAA is typically a concern in patients presenting with acute abdominal or flank pain, as 4–8% of older men (and slightly fewer women) have occult aneurysms. Similarly, thoracic aortic dissection is a differential diagnostic consideration for patients presenting to the ED with chest pain. Given the low frequency (but high morbidity and mortality) of aortic emergencies, ED evaluation should appropriately focus on screening modalities with high accuracy. While computed tomography angiography (CTA) has become the current criterion standard for both disease processes (replacing traditional angiography due to its greater availability), it carries with it the potential risks of contrast‐induced nephropathy, allergy, and radiation‐induced malignancy, as well as the time delay involved with its use in a busy ED. As a result, plain chest radiography and D‐dimer have been considered as risk‐stratification tools for the presence of an aortic dissection, and the use of bedside ultrasound has been advocated to screen for AAA.

Clinical question

Which findings on the history or physical examination increase or decrease the likelihood of a patient with chest pain having an acute aortic dissection? Is chest radiography or D‐dimer testing appropriate for excluding aortic dissection in patients presenting with chest pain?

A meta‐analysis by Klompas¹ in 2002 reviewed the test characteristics of physical examination and radiographic findings for aortic dissection. As few studies met criteria for inclusion, the author was only able to develop pooled data for 1553 patients and analyze one historical factor (history of hypertension), one symptom (sudden chest pain), two signs (pulse deficit and a diastolic murmur), and one radiographic finding (enlarged aorta or wide mediastinum). The results (Table 42.1) demonstrate that, while the presence of a pulse deficit increases the likelihood for aortic dissection, no element in the history or physical exam is sensitive enough to reliably rule out the disease.

A more recent meta‐analysis by Ohle² in 2018 delved further into whether there were physical examination findings that might increase or decrease the likelihood of aortic dissection. The authors included nine studies with a total of 2400 patients; the prevalence of aortic dissection in the studies varied from 22% to 76%. They concluded that the presence of either a neurological deficit (LR+ 4.4, confidence interval [CI] 3.3–5.7) or hypotension (LR+ 2.9, CI 1.8–4.6) significantly increased the likelihood of disease in patients suspected of having aortic dissection.

Table 42.1 Accuracy of clinical findings for thoracic aortic dissection

Source: Data from [1].

Symptom or sign	Positive likelihood ratio (LR+) (CI)	Negative likelihood ratio (LR−) (CI)
History of hypertension	1.6 (1.2–2.0)	0.5 (0.3–0.7)
Sudden chest pain	1.6 (1.0–2.4)	0.3 (0.2–0.4)
Pulse deficit	5.7 (1.4–23.0)	0.7 (0.6–0.9)
Diastolic murmur	1.4 (1.0–2.0)	0.9 (0.8–1.0)
Enlarged aorta or wide mediastinum	2.0 (1.4–3.1)	0.3 (0.2–0.4)

Similarly, while a chest X‐ray finding of a widened mediastinum was 90% sensitive for thoracic aortic dissection, given the significant morbidity of the disease it was not an appropriate screening exam in patients with a high pretest probability of disease. A study by von Kodolitsch et al

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