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Trahanas et al. Vessel Plus 2022;6:49 https://dx.doi.org/10.20517/2574-1209.2021.125 Page 5 of 16

The morphology of the dissected aorta will change over time. As remodeling occurs, the dissection may
extend into new aortic zones or regress out of previously injured zones, and the extent of the disease burden
[3]
should be updated using the SVS/STS classification system . The important parameters to document are
total aortic diameter, true lumen and false lumen diameter, distal entry tears, and the status of the false
lumen, including whether it is patent, partially thrombosed, or completely thrombosed . Multiphase
[3]
computed tomography angiography (CTA) is the imaging modality of choice for CTBAD due to its
sensitivity for detection of false lumen flow, false lumen thrombosis, changes in aortic diameter, and prior
treatment/device complications . Delayed contrast phase imaging is important to reveal any delayed false
[3]
lumen perfusion by distal fenestrations [16,17] . Other imaging modalities such as magnetic resonance
[12]
angiography and echocardiography may also be considered in select patients .

Indications for surgical intervention
Any consideration of intervention on the aorta must balance the patient’s life expectancy versus the risk of
the procedure. For most patients, an aneurysm of the descending thoracic aorta > 5.5 cm warrants
intervention. This is based on data demonstrating that 23% of patients with rupture of a chronically
dissected aorta had an aortic dimension between 5 and 6 cm, with a median last known aortic diameter of
5.4 cm [18,19] . This size criterion may be adjusted based on the size of the patient and the size of their normal
contiguous aorta, and typically an aneurysm more than twice the size of the normal contiguous aorta should
be considered for replacement .
[9]

Indications for intervention at smaller sizes may include rapid growth of the aneurysm (> 5 mm -10 mm in
12 months) or a saccular aneurysm protruding 2 cm or more beyond the aortic wall . Connective tissue
[2]
disorder, family history of aortic catastrophe, contained aortic rupture, penetrating aortic ulcer, mycotic
[9]
aneurysm, or new acute on chronic dissection may also warrant intervention at smaller sizes . Symptomatic
aneurysms should be treated regardless of size because symptoms typically herald impending rupture .
[9]
Surgical management
CTBAD may be treated by endovascular, open surgical, or hybrid approaches. Regardless of the strategy,
common goals include limiting the extent of the aorta that is repaired to minimize associated morbidity,
maintaining end-organ perfusion, and reducing the risk of dissection-related death . The way these goals
[9]
are achieved differs between endovascular and open surgical management. The objective of open surgical
management is to replace the aneurysmal segment of the aorta. The objective of endovascular intervention
is to cover the false lumen entry tears and promote false lumen thrombosis and positive aortic
remodeling [2,20] .

Deciding which intervention strategy to choose requires careful consideration of the anatomic features of
the dissected aorta, including the site of entry tears, longitudinal extent of involvement, locations of
fenestrations and branch vessels, as well as patient co-morbidities and life expectancy .
[4,9]

Patients being considered for open surgery to repair a descending thoracic aneurysm (DTA) or
thoracoabdominal aortic aneurysm (TAAA) because of a CTBAD must have a thorough assessment by an
experienced surgeon, preferably at a center of excellence/aortic referral center with high volume experience
in performing these complex procedures. Consideration of patient age, co-morbidities, symptomatology,
life expectancy, quality of life, aneurysm morphology and extent, and operator experience are all important
considerations . Open TAAA repairs are among the most anatomically violating and physiologically
[9]
insulting surgical procedures performed in the modern era, with a 1-year morbidity and mortality of 17%-
[21]
20% . Due to the nature of the operation, the abdominal organs and spinal cord are exposed to a period of
ischemia, making them vulnerable to injury . Additionally, the unique combination of the
[21]