5.0 Treatment
The challenges associated with the treatment of non-A non-B aortic
dissections are well recognised and in amongst this surgical field there
is currently no gold standard consensus on how to treat acute non-a
non-b. Due to the infrequency of presentation of non-a non-b
dissections, the literature is currently significantly reduced on this
topic, however various studies from across the world have utilised many
of these techniques with a differing spectrum of intra-operative and
post-operative results published.
Various surgical approaches exist however endovascular treatment has
been shown in a recent systematic review and meta-analysis to be the
most widely used technique (Brown et al. , 2020) (Carino et
al. , 2019). In their study, TEVAR made up a significant percentage of
surgical treatments for Non-A non-B dissections; TEVAR with
extrathoracic surgical transposition of the supra aortic branches was
adopted in 18% of surgeries and TEVAR with chimney stent graft in 36%
of cases (Carino et al. , 2019). A growing proportion of studies
also list TEVAR as the treatment of choice for acute complicated and
many chronic type B and Non-A non-B aortic dissections (Shresthaet al. , 2015; Brown et al. , 2020). Success of an
endovascular approach for this subset of dissection patients is with
some growing consensus attributed to the closure of the primary entry
tear (Erbel et al. , 2014). Application of different thoracic
endovascular aortic repair (TEVAR) zones is used to enable effective
entry tear closure. For descending entry patients that have an entry
tear distal to the left subclavian artery, TEVAR zone 3 (landing zone
that is distal to left subclavian artery) and TEVAR zone 2 (landing zone
that is between the left subclavian and left common carotid) for more
proximal entry tears just at the edge of the left subclavian artery
(Rylski et al. , 2017). Despite TEVARs more widespread use, an
endovascular approach of this type might not always be feasible due to
the lack of an adequate proximal landing zone as well as an increased
risk of retrograde type A dissection which is particularly apparent in
patients with additional aortic pathologies in zones 1 to 3 (Shresthaet al. , 2015). Application of TEVAR in patients with connective
tissue diseases is also controversially reported in the literature
(Czerny et al. , 2019b; Czerny et al. , 2019a; Kreibichet al. , 2018; Shrestha et al. , 2015). Therefore, in a
scenario in which an entry tear is located in the aortic arch, a more
extensive arch repair such as a hybrid aortic repair involving rerouting
of the supra-aortic arteries with TEVAR zone 0 (landing zone at the
ascending aorta) or even a complete arch replacement utilising the
frozen elephant technique (FET), could be necessary in order to close
the primary entry tear (Czerny et al. , 2019b).