The Role of Imaging in Aortic Dissection and Related Syndromes
This state-of-the-art paper summarizes the current role of aortic imaging in patients with aortic dissection and other acute aortic syndromes. The following are key points to this article:
1. Imaging plays a critical role in identifying and following acute aortic syndromes, and current options include computed tomography (CT), magnetic resonance imaging (MRI), and transesophageal echocardiography (TEE).
2. TEE can be performed at the bedside and is highly accurate to identify aortic dissection, although it requires sedation, and has a blind spot in the upper ascending aorta. TEE may be particularly useful to assess dynamic side-branch occlusions, aortic valve function, involvement of the coronary arteries, communication between the true and false lumens, and evaluation of flow into the true and false lumens.
3. TEE has limited utility in serial imaging due to its incomplete aortic imaging and lack of landmarks permitting direct comparison separate studies.
4. CT is the most widely used test to evaluate suspected acute aortic syndromes, as it is a rapid, widely available, and has excellent diagnostic accuracy. Complete aortic imaging permits direct comparisons of serial images to evaluate changes over time. The acquisition of an isotropic three-dimensional data set permits reconstruction in any plane, allowing short-axis imaging of any portion of the aorta.
5. Disadvantages of CT include patient exposure to ionizing radiation, which is increased when electrocardiography (ECG)-gating is used. The need for iodinated contrast is associated with a risk of contrast-induced nephropathy in some patients, such as those with existing renal insufficiency.
6. MRI also has high diagnostic accuracy to identify acute aortic syndromes. It does not require iodinated contrast, and does not expose patients to ionizing radiation. MRI is currently not used as often as CT, as it is less widely available; presents challenges or is a contraindication in patients with pacemakers, defibrillators, or other metallic implants; and is a much slower test than CT.
7. Aortic MRI includes multiple sequences that can be used to visualize the aortic wall, aortic lumen, dissection flaps, three-dimensional imaging of blood flow, and aortic regurgitation. MRI may be superior to CT for detection of small intramural hematomas.
8. As TEE, CT, and MRI all have excellent diagnostic accuracy, selection of which test to use should be determined based on the clinical scenario, availability, and local expertise. For unstable patients, transthoracic echocardiography and TEE may be the most appropriate initial tests.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Noninvasive Imaging, Vascular Medicine, Implantable Devices, SCD/Ventricular Arrhythmias, Aortic Surgery, Cardiac Surgery and Arrhythmias, Echocardiography/Ultrasound, Magnetic Resonance Imaging
Keywords: Defibrillators, Renal Insufficiency, Imaging, Three-Dimensional, Aortic Aneurysm, Thoracic, Radiation, Ionizing, Coronary Vessels, Hematoma, Magnetic Resonance Imaging, Echocardiography, Transesophageal
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