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Page 4 of 7 Harky et al. Vessel Plus 2018;2:8 I http://dx.doi.org/10.20517/2574-1209.2018.12

IS EVERYONE A CANDIDATE FOR TEVAR?
Although TEVAR seems an attractive option for managing patients with rDTAA, it cannot be used as a
[3]
standard management in every patient at the time of presentation due to many factors . Initially the gold
[19]
standard method for managing such patients was OR , however this method has been challenged by the
evolution of TEVAR and the favourable short-term outcomes [16,20,21] . One of the key factors in choosing
TEVAR over OR, is the anatomic variations and suitability for TEVAR. To assess such anatomical variation,
thorough imaging studies are required such as computerized tomography and magnetic resonance imaging
[3]
to assess such anatomical suitability . Cross-sectional imaging of the aorta is essential, alongside detailed
aortic pathology assessment using computerized tomography aortogram. Although obtaining such imaging
can be time consuming and may delay the immediate management, they are crucial to determine the
[19]
location and extent of the pathology so that appropriate interference can be implicated . It is not only
important to obtain knowledge about the pathology itself, but rather the assessment of the neck vessels,
vertebral arteries and access point vessels are of paramount to evaluate for suitable of endovascular repair,
which provides a sufficient amount of information for a rapid decision about whether to perform TEVAR or OR.

An important factor considering TEVAR for rDTAA is the quality of the landing zones. The application
for traditional TEVAR requires a proximal and distal landing zone of at least 2 cm. However, patients
who present with thoracic aortic pathology can have disease extending to the aortic arch, resulting in
an unsuitable proximal landing zone distal to the left subclavian artery. In order to optimize outcome
and reduce complications following the graft placement in zones 0, 1 or 2 of the aortic arch, planning for
revascularization of the aortic vessels is essential to prevent neurovascular compromise and risk of stroke.
Therefore, when TEVAR is extended into zone 2 further procedures such as left carotid-subclavian artery
bypass or left carotid-subclavian artery transposition is warranted. When TEVAR is extended into zone 1
of the aortic arch, the left common carotid artery requires revascularization via carotid-carotid crossover
[22]
bypass .
Traditionally, patients with calcified vessels, difficult anatomy and an inability to identify suitable access
points, as well as patients with connective tissue disorders, are offered open repair over TEVAR [7,16,23] .

OPEN OR ENDOVASCULAR REPAIR FOR rDTAA?
The choice of OR or TEVAR in patients presenting with rDTAA remains debatable at present. In many
centers internationally TEVAR is offered as the first line treatment for these patients unless contraindicated,
such as patients with connective tissue disorders, except as a temporizing solution until definitive surgery
[24]
can be performed . The choice of TEVAR also depends largely on the available expertise and the anatomic
limitations of the DTA, as discussed above.

TEVAR itself offers a minimal access procedure and thus saving major operating time and reducing
perioperative complications associated with OR. Stabilization of the patient through aggressive resuscitation
is a key step in preparing the patient for either OR or TEVAR. This includes potentially controlling of the
source of bleeding through either application of a clamp at the proximal aorta in OR or balloon inflation in
the case of TEVAR; however the later seems to be less efficient technically in providing adequate control of
[3]
the bleeding . An advantage of TEVAR is the selection of anaesthetic technique. It is possible to perform
TEVAR under either local, regional or general anaesthesia, in contrary to OR where it can be performed
only under general anaesthesia. Therefore, patients with advanced cardiopulmonary comorbidities and those
who are unfit for OR may potentially be a suitable candidate for TEVAR and thus a life saving procedure can
[25]
be performed .

Neuroprotection in patients undergoing repair of rDTAA is a key step for a favourable outcome. This
includes stabilization of spinal cord perfusion pressure through placement of a lumbar drain to avoid the