Nontraumatic Acute Aortic Emergencies: Part 1, Acute Aortic Syndrome

Abstract

Acute aortic syndrome includes acute aortic dissection, intramural hematoma, and penetrating atherosclerotic ulcer. The most common clinical presentation is severely painful and potentially life-threatening abnormalities of the aorta. Differentiating among these aortic diseases is impossible by symptoms or physical evaluation. Therefore, any clinical suspicion should prompt immediate action including confirmatory noninvasive imaging. Prognosis of acute aortic syndromes is clearly related to prompt diagnosis and appropriate management. Accurate imaging interpretation can modify the natural history of acute aortic syndrome and improve prognosis.

The role of multidetector-row CT in the diagnosis, classification and management of acute aortic syndrome

“…25,[27][28][29][30] The use of electrocardiogram (ECG) gating in the evaluation of AAS is essential to reduce cardiac motion artefacts that may mimic aortic dissection, particularly in the evaluation of the aortic root and ascending aorta (Figures 1 and 2). 4,31,32 In addition, ECG gating also enables more accurate assessment of the proximal coronary arteries in patients with confirmed aortic dissection. 28,31 Although ECG-gated imaging of the thoracic aorta is not yet routinely performed in all institutions, it should be noted that this approach may potentially lead to the inappropriate transfer of patients to cardiothoracic surgical centres or even negative open surgery for patients with atypical cardiac motion artefact mimicking acute dissection flaps on non-ECG-gated MDCT (Figure 2).…”

“…ECG-gated pre-contrast image acquisition from above the aortic arch to diaphragmatic hiatus to evaluate for the presence of IMH and localized rupture into the pleura or pericardium is an important component of the imaging protocol for patients with suspected AAS and should be performed in all such patients. 4,31,33 Following the unenhanced study, a bolustracked CT angiogram should be performed using 120 ml of 370 mg l ml 21 iodinated contrast medium delivered at a rate of between 4 and 5 ml s 21 via a power injector to achieve a target opacification of the aorta of .250 HU. 34 The volume of contrast should be reduced to 80-100 ml in elderly patients with reduced cardiac outputs.…”

“…41 The entrance tear is most commonly seen at the sites of the greatest hydraulic stress, located at the right lateral wall of the ascending aorta or the proximal segment of the descending aorta. 4,38 Many patients have a re-entrance tear and several fenestrations between the TL and FL along the course of the dissected segment of the aorta. 38,42 The cardinal features of aortic dissection on MDCT are the presence of an intimomedial flap and a double-channel aorta (Figures 4 and 5).…”

“…38,42 The cardinal features of aortic dissection on MDCT are the presence of an intimomedial flap and a double-channel aorta (Figures 4 and 5). 4,25,28,32 Once the diagnosis of acute aortic dissection has been made on MDCT, the key is to classify the origin and extent of the dissection, to differentiate the TLs and FLs and to assess for branch vessel involvement and complications. 3,4,25 It is important to remember that cardiac motion and streak artefacts may mimic a dissection flap.…”

“…2,3 These different pathological entities can be difficult to distinguish clinically and may be confused with other causes of chest pain, including myocardial infarction, oesophageal perforation or pulmonary embolism. [2][3][4] Aortitis and traumatic aortic injury are not considered as part of the clinical spectrum of AAS, as they both demonstrate distinct pathophysiological and clinical features. 2,3 We provide a literature review of the role of multidetectorrow CT (MDCT) in the acute assessment of patients with suspected AAS and highlight the importance of early diagnosis and accurate classification in the management of AAS.…”