Ciara O'Brien;
University Health Network; University of Toronto
Darragh Halpenny;
Tallaght University Hospital
William Torreggiani;
Tallaght University Hospital
Background
A spectrum of acute aortic pathology exists, both traumatic and non-traumatic. The incidence of an acute aortic syndrome (AAS) ranges from 3.5 - 6 per 100,000 person years in the general population, although with a higher quoted incidence as high as 10 per 100,000 person-years in an older population. Facilitating prompt access to imaging is critical, as well as prompt recognition and communication of findings to colleagues to ensure the best patient outcome.
Educational Goals / Teaching Points
This presentation aims to review the classification of acute aortic syndromes, outline salient imaging findings seen in the setting of AAS, and highlight the importance of an appropriate study protocol to answer the clinical question with confidence.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
CT is the modality of choice for the acute diagnosis of acute syndromes and can also help to determine end-organ involvement or malperfusion. CT is also the mainstay for follow-up of an acute presentation and/or lesion repair. Complementary imaging modalities, such as chest radiography or echocardiography may be useful as first line imaging tests, particularly in the acute setting with an unstable patient. ECG-gated CT angiography is the preferred test of choice in investigating patients with suspected AAS. However, ECG-gating may not always be feasible if patients are hemodynamically unstable with tachycardia, have arrythmia, or if administering rate control therapy, which may pose an unacceptable clinical risk. Aortic dissection and or intramural hematoma can be considered as Stanford type A or B, depending on whether or not the ascending aorta is involved. Type A dissection involves the aortic root. A noncontrast volume enhances the detection of acute aortic intramural hematoma, seen as aortic intramural hyperdense material. The angiographic phase of acquisition can depict a dissection flap, allowing accurate characterization of where the lesion originates and extends to. This is of paramount importance to help guide management of the patient. Specifically, involvement of end-organ vessels is critical when interpreting imaging, including the coronary arteries if the aortic root is involved, the origin of the great vessels if the lesion extends to involve the aortic arch, the major abdominal visceral branch vessels as well as the ilio-femoral arterial tree. Penetrating atheromatous ulcers are typically recognized as a smooth-walled outpouching from the aorta. There may or may not be associated mural hematoma in the wall or thrombus within the sac. Aortic root abscesses can occur with both native and prosthetic valves. Aortic mycotic aneurysms occur most frequently following bacterial infection. Both can lead to acute clinical deterioration and should always be considered in the appropriate setting if there is also a history of sepsis.
Conclusion
We present a series of cases of both traumatic and nontraumatic AAS. We highlight the importance of accurate study protocol in highlighting critical pathology.
