Aortic dissection imaging in acute aortic dissection

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Case #1

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2]

Overview

There are a wide variety of imaging studies that can be used to diagnose aortic dissection, but in general, transesophageal imaging is the imaging modality of choice in the acutely ill patient and MRI is the imaging modality of choice in the assessment of longstanding aortic disease in a patient who has chronic chest pain who is hemodynamically stable or for the evaluation of a chronic dissection.

Use of Transesophageal Echo Imaging in the Acute Setting

In the management of the acute patient with suspected aortic dissection, a transesophageal echo performed acutely in the emergency room is the preferred approach. If the patient is hemodynamically unstable, then a transesophageal echo can be performed in the operating room as the patient after the patient has been induced and is being prepared for surgery.

Use of MRI Imaging in the Absence of Acute Disease

MRI is the imaging modality of choice in the assessment of

• A patient who has chronic chest pain who is hemodynamically stable
• A chronic dissection

Use of CT Scanning

A CT scan can be used if neither a TEE nor MRI is available in a timely fashion, or if there is a contraindication to their performance. An example would be after hours in an emergency room setting. IF the results of the CT scan are non-diagnostic, they TEE or MRI should be performed to confirm the diagnosis.

Use of Aortography

Aortography is rarely used in the modern era. It can be used of the other imaging modalities are not available or are inconclusive.

Use of Coronary Angiography

Pre-operative angiography has not been associated with improved outcomes in retrospective analyses. It is reasonable to perform coronary angiography in the following scenarios:

• Age over 60 years
• Presence of CAD risk factors
• History of prior myocardial infarction

2010 ACC/ AHA Guidelines - Recommendations for Screening Tests (DO NOT EDIT)

Class I

1. An electrocardiogram should be obtained on all patients who present with symptoms that may represent acute thoracic aortic dissection.

a.Given the relative infrequency of dissection-related coronary artery occlusion, the presence of ST-segment elevation suggestive of myocardial infarction should be treated as a primary cardiac event without delay for definitive aortic imaging unless the patient is at high risk for aortic dissection (Level of Evidence: B)

2.The role of chest x-ray in the evaluation of possible thoracic aortic disease should be directed by the patient's pretest risk of disease as follows:

a. Intermediate risk: Chest x-ray should be performed on all intermediate-risk patients, as it may establish a clear alternate diagnosis that will obviate the need for definitive aortic imaging (Level of Evidence:C)

b. Low risk: Chest x-ray should be performed on all low-risk patients, as it may either establish an alternative diagnosis or demonstrate findings that are suggestive of thoracic aortic disease, indicating the need for urgent definitive aortic imaging. (Level of Evidence:C)

3.Urgent and definitive imaging of the aorta using transesophageal echocardiogram, computed tomographic imaging, or magnetic resonance imaging is recommended to identify or exclude thoracic aortic dissection in patients at high risk for the disease by initial screening (Level of Evidence: B)

Class III (No Benefit)

1. A negative chest x-ray should not delay definitive aortic imaging in patients determined to be high risk for aortic dissection by initial screening.(Level of Evidence: C)